By B. Jesper. Clarion University.
The integration of the considerations for drug delivery and targeting into the drug design process may ultimately allow the development of drugs which are not just potent and non-toxic but offer the advantage that their chemical structure dictates the targeting of the drug to its particular site of action through enzyme-based chemical delivery systems using prodrugs cheap 2.5 mg provera free shipping. A prodrug is a pharmacacologically inactive compound which undergoes chemical or enzymatic metabolism to the active cheap provera generic. Some of the early pharmaceuticals were found to be prodrugs and this finding has led to the subsequent introduction of the metabolite itself into therapy buy provera 2.5 mg without prescription, particularly in cases where the active metabolite is less toxic or has fewer side-effects than the parent prodrug. The administration of the active metabolite may also reduce variability in clinical response between individuals due to differences in pharmacogenetics. Most chemically designed prodrugs consist of two components; the active drug chemically linked to a pharmacologically inert moiety. The prodrug must be sufficiently stable to withstand the pharmaceutical formulation while permitting chemical or enzymatic cleavage at the appropriate time or site. After administration or absorption of the prodrug, the active drug is usually released by either chemical or enzymatic, hydrolytic or reductive processes. Prodrugs are most commonly used to overcome the biological and pharmaceutical barriers which separate the site of administration of the drug from the site of action (Figure 16. Prodrug design has been used to address a wide range of pharmaceutical problems including: • unpalatability • gastric irritation • pain on injection • insolubility • instability. Prodrug design has also been used widely to address pharmacological problems such as poor drug adsorption and drug distribution. As discussed in Chapter 1, prodrugs may be used to enhance the absorption of poorly adsorbed drugs by increasing the lipophilicity of the drug molecule. The modification of a drug to a prodrug may also lead to enhanced efficacy by differential distribution of the prodrug to particular body tissues before the release of the active drug. For example, the administration of the methoxymethyl ester of hetacillin (a 6-side-chain derivative of ampicillin) leads to a more extensive distribution of ampicillin in the body tissues than occurs on administration of ampicillin itself. Conversely, the restriction of tissue distribution which decreases toxic side-effects by restricting the action of a drug to a specific target site in the body may also be achieved through the use of certain prodrug systems as described below. An alternative strategy is to utilize phenotypic differences between cell types to target prodrugs to particular sites within the body through site- specific enzyme-based delivery systems. Improved selective localization of anticancer agents to neoplastic tissue may be achieved using non-toxic prodrugs which release the active drug within the tumor as a result of enhanced enzyme activity in the cell. For example, the prodrug cyclophosphamide is initially activated by hepatic cell enzymes to generate 4- hydroxycyclophosphamide which is then specifically converted to the alkylating cytotoxic phosphoramide mustard in the target cells. As the blood supply to large solid tumors is disorganized, the internal regions are often non-vasculated and the cells, termed hypoxic, deprived of oxygen. The absence of molecular oxygen enhances the reductase activity in hypoxic tissues providing an alternative means of targeting the internal regions of solid tumors using a selective chemical prodrug-delivery system. Certain aromatic, heterocyclic nitro-containing compounds can be reduced in hypoxic environments to produce intermediates which then fragment into alkylating species. For example, the 2-nitro-imidazole compound misonidazole is selectively cytotoxic to cultured hypoxic cells. An alternative approach utilizes the bioactivation of aromatic nitrogen mustards through the reduction of a substituent group in the aryl ring. More recently it has been suggested that bioreductive technologies may have applications in the treatment of other disease states. For example, it has been suggested that the essential role of hypoxia in rheumatoid arthritis offers opportunities to specifically deliver anti-inflammatory agents to arthritic joints using bioreductive prodrugs. This will allow the future development of prodrug-based chemical delivery systems to target specific cell types through the use of the upregulated enzymes in diseased tissues to release the active drug. Furthermore, therapeutic levels of lipophilic prodrugs in the brain can only be maintained if there is an equivalent constant plasma concentration. These problems may be overcome by utilizing a drug delivery system which relies on “trapping” a prodrug in the brain by oxidizing the prodrug to a less membrane permeable derivative. Both phenylethylamine and dopamine have been used to illustrate the principles of this technology and in vivo work has been described in animal studies. The 1,4-dihydro-prodrug is prepared by reduction of a quaternized nicotinic acid derivative of phenylethylamine. On administration the prodrug is delivered directly to the brain, where it is oxidized and trapped as the quaternary ammonium salt. The metabolism and elimination of the drug from the periphery removes excess drug and metabolic products during and after onset of the required action. This overcomes the need to maintain plasma levels which may cause systemic side-effects. The approach has been used most extensively to target drugs to tumor cells by employing an enzyme, not normally present in the extracellular fluid or on cell membranes, conjugated to an antitumor antibody which localizes in the tumor via an antibody-antigen interaction on administration. Following clearance of any unbound antibody conjugate from the systemic circulation, a prodrug, which is specifically activated by the enzyme conjugate, is administered. The bound enzyme-antibody conjugate ensures that the prodrug is only converted to the cytotoxic parent compound at the tumor site thereby reducing systemic toxicity. For example, using cytosine deaminase to generate 5- fluorouracil from the 5-fluorocytosine prodrug at tumor sites increases the delivery to the tumor by 17 fold compared to that achieved on administration of 5-fluorouracil alone. The localized β-lactamase enzyme, which is not normally found in any other tissues, ensures selective release of taxol at the tumor site. The prodrug A is delivered directly to the brain, where it is oxidized and trapped as the prodrug B. The quaternary ammonium salt is slowly cleaved by chemical/enzymatic action with sustained release of the biologically active phenylethylamine C and the facile elimination of the carrier molecule D. Suicide genes encode for nonmammalian enzymes which can be used to convert a prodrug into a cytotoxic agent. Cells which are genetically modified to express such genes essentially commit metabolic suicide on administration of the appropriate prodrug. Typical suicide genes include herpes simplex thymidine kinase and Escherichia coli cytosine deaminase. Although any gene delivery vector may be employed to deliver the gene (see Section 14. These chemical approaches to advanced drug targeting are embryonic and their future development will be dependent on the “fruits” of the genomic and proteomic revolutions. Even though it may ultimately be possible to develop site-specific chemical drug delivery systems for a wide range of therapeutic applications, there will still be a need to address the challenges of chronopharmacology in order to achieve better therapeutic control. Such control requires means of sensing and responding to changes in biological stimuli. This can be achieved by having either a separate biosensor which electronically controls drug release from a drug delivery device or a combination system in which the stimulus has a direct effect on the release of drug from the system. Such a system quantifies electronic signals arising from the interaction between a biosensor and an analyte of interest. Catalytic biosensors use enzymes, microorganisms, or whole cells to catalyze a reaction with the target analyte, while affinity biosensors utilize antibodies, receptors, or nucleic acids to bind with the target analyte. The integration of biosensors with drug delivery systems allows the controlled release of a drug substance in response to the levels of biological modulator.
The source of the bleeding generally is right sided (60%) cheap provera 2.5mg line, even though diverticula generally are present on the left cheap provera 10mg free shipping, and the source typically is a single diverticulum order provera 10mg with visa. The majority of patients (70–82%) stop bleeding, but 12% to 30% continue to bleed and require interven- tion. The cause of the hemorrhage appears to be erosion into the vasa recta that courses along the diverticula. Patients with diverticular hemorrhage frequently present with self- limited, minor episodes of bleeding. Patients often describe intermit- tent passage of bright red or maroon blood per rectum. Physical exami- nation usually is unremarkable, and evidence of abdominal tenderness is absent. Treatment for persistent or recurrent bleeding from a known diverticular source traditionally is to remove the affected segment of colon. Although bleeding generally is considered to be from a single vessel, endoscopic electrocoagulation has been consid- ered to carry a high risk of perforation of the adjacent diverticulum. Most of these lesions remain asymptomatic and typically occur in the elderly population, with the average age being 70. There- fore, the best diagnostic tool remains visceral angiography, which reveals a tortuous knot of blood vessels, sometimes with early ﬁlling of a large vein. Corbett rebleeding from these lesions is high, with patients often experiencing three to ﬁve bleeding episodes before a diagnosis is made. Angiodys- plasias can be managed successfully by colonoscopy and treated by endoscopic electrocoagulation. Neoplasms: In recent series, the incidence of massive colonic bleeding from ulcerated carcinomas or polyps ranged from 6% to 32%. Polyps may be amenable to endoscopic removal, but most carcinomas require resection. Inﬂammatory Bowel Disease: Although ulcerative colitis and Crohn’s disease both are characterized by bleeding and diarrhea, massive bleeding is quite uncommmon, representing only about 3% to 5% of those presenting with massive hematochezia. Ischemic Colitis: Ischemic colitis is the most common form of intestinal ischemia. It is thought to affect “watershed” areas of the colon where two blood supplies may incompletely overlap: the splenic ﬂexure sup- plied by the left branch of the middle colic artery and the ascending left colon. The severity of injury appears to be related to multiple factors includ- ing duration of ischemia, vessel caliber, acuity of ischemia onset, col- lateral circulation, and virulence of intestinal bacteria. The onset may be insidi- ous, not recognized, or attributed to the medical comorbidities. Onset of acute colonic ischemis is heralded by the sudden onset of crampy abdominal pain. This may be associated with bloody diarrhea, fever, abdominal distention, anorexia, nausea, or vomiting. Physical exam may reveal abdominal distention and tenderness over the involved segment. With transient intestinal ischemia, superﬁcial sloughing of the mucosa, submucosal hemorrhage, and edema generally resolve within 1 to 2 weeks without permanent sequelae. The bleeding scan is performed and within 15 minutes suggests an area of active hemor- rhage in the right colon. Arteriography conﬁrms the location of the bleeding site in the ascending colon, originating from a single vessel. The following day, after receiving a gentle bowel prep, a colonoscopy is performed. The procedure demonstrates numerous diverticuli in the descending and sigmoid colon. Patients who have evidence of massive blood loss should be resuscitated immediately. A careful history and a physical exam may provide clues to the etiology of the hemorrhage. If the patient is stabilized in the emergency room and hematemesis or bloody nasogastric aspirate has been documented, upper endoscopy is the standard of care for diagnosis and for segregating patients into low- and high-risk groups. Endoscopic treatment of those with major stigmata of ulcer hemorrhage is recommended. Surgical consultation should be obtained and the likelihood for surgical intervention will depend on the etiology of the bleed. The ﬁrst step in management of patients who present with rectal bleeding, stable or unstable, is a rigid sigmoidoscopy to exclude rectal lesions as a cause. If the patient is stable but has evidence of ongoing bleeding and the sigmoidoscopy is unrevealing, angiography and radionuclide scanning can be consid- ered, with radionuclide scanning being the preferred ﬁrst test. The major- ity of patients with bleeding diverticula (70–82%) stop bleeding, but 12% to 30% continue to bleed and require intervention. Urgent colonoscopy for the diagnosis and treatment of severe diverticular hemorrhage. To recognize surgical conditions that require further evaluation and eventual operation. Cases Case 1 A 78-year-old man with a history of myocardial infarction and coro- nary artery bypass surgery is brought to the hospital by ambulance because of severe abdominal pain that suddenly began 6 hours ago. The patient is confused and disoriented, but he indicates that the pain is excruciating. The patient’s wife reports that he had an urgent desire to defecate when the pain began, but no further stool or ﬂatus has been noted. She provides a list of current medications that includes digoxin, pindolol (a beta-blocker), a baby aspirin, and a nitrate patch. Wise On examination, he appears gravely ill with cool ashen skin, an irregular pulse of 120, blood pressure of 85/50, and respirations at 28. Case 2 An 18-year-old male college student is awakened with an aching pain in the periumbilical area, anorexia, and nausea. He skips morning classes and chews a few antacid tablets, but, later in the day, the pain becomes worse, more constant, and moves to the right lower quadrant. Unable to eat, he vomits once and notes that the pain is worse when he tries to walk. At the hospital inﬁrmary, he is found to have lower right quadrant tenderness, involuntary guarding, an oral temperature of 100. Case 3 A 59-year-old man is referred to the hospital emergency department by his physician because of lower abdominal pain, fever, and difﬁculty walking. The patient has noted intermittent cramps and changing bowel habits over the past 2 months. Recently, he has become constipated, but he also has had occasional episodes of diarrhea.
In patients with risk factors for diabetes cheap provera, obtain fasting blood glucose test results at baseline and periodically discount provera generic. If changes in patients medical condition (including development of leukopenia) require that drug be stopped immediately safe 5mg provera, monitor patient closely for recurrence of psychosis. Reexposure of patient to drug may increase severity and risk of adverse reactions. Advise him to report flulike symptoms, fever, sore throat, lethargy, malaise, or other signs of infection. Adjust dosage, if necessary, no more frequently than every 2 days; to allow for lowest possible doses, the interval should be several weeks to assess symptom response. Doses of 10 mg may be given every 2 hours; doses of 20 mg may be given every 4 hours. Oral route has an onset of 1 - 3 days with a peak of 6 – 8 hours and a duration of 12 hours. Nursing Considerations: Not recommended for treatment for children with Batten Disease. Slight yellowing of injection or concentrate is common and does not affect potency. It may not appear until months or years later and may disappear spontaneously or persist for life, despite ending drug. Available forms are: capsules: 150 mg, 300 mg, 600 mg; tablets 250 mg, 300 mg (300 mg equals 8. Use with caution, and monitor Lithium (antipsychotic) and electrolyte levels (especially sodium). Advise patient who ingests large amounts of caffeine to tell their Physician before stopping caffeine. Monitor Lithium (antipsychotic) level 8 to 12 hours after first dose, the morning before second dose is given, two or three times weekly for the first month, then weekly to monthly during maintenance therapy. Under normal conditions, patient fluid intake should be 2½ to 3 liters daily and he should follow a balanced diet and adequate salt intake. Maximum, 200 mg daily for children ages 8 - 11 and 300 mg daily for children ages 11 - 17. For adults, initially, 50 mg daily at bedtime, increase by 50 mg every 4 - 7 days. Nursing Considerations: Benzodiazepines, Theophylline (used for acute bronchospasm), Warfarin/Coumadin (to thin the blood) – may reduce clearance of these drugs. Once improvement occurs, advise patient not to stop drug until directed by Physician. It may not appear until months or years later, and may disappear spontaneously or persist for life, despite discontinuing drug. It may not be related to length of drug use or 211 type of neuroleptic; more than 60% of affected patients are men. Slight yellowing of injection or concentrate is common and does not affect potency. It may not appear until months or years later and may disappear spontaneously or persist for life, despite ending drug. It may not be related to length of drug use or type of neuroleptic; more than 60% of affected patients are men. This medication acts to balance two nerve impulses and by doing so, helps restore more normal thinking and mood, has fewer side effects. Of children age 5 and older and adolescents, with a guideline of children 216 weighing 20 kg or 44 lbs. Nursing Considerations: Children with Batten Disease can have fairly severe withdrawal symptoms if stopped abruptly, very agitated, increased movement, and uncontrollable. It may not appear until months or years later and may appear spontaneously or persist for life, despite stopping drug. Suspension appears uniform, thick, and milky; particles are visible, but no dry particles remain. Drug should be used immediately, but may be refrigerated up to 6 hours of 218 reconstitution. Drug can be stored at temperature less than 77 degrees F (25C) for no more than 7 days before administration. Peel apart the foil to expose the tablet; do not attempt to push it through the foil. Further dosage adjustments, if indicated, should occur at intervals of not less than two days. Nursing Considerations: Antihypertensives may increase effects of antihypertensives. It may not appear until months or years later and may disappear spontaneously or persist for life, despite ending drug. Reduces sympathetic outflow from the vasomotor center to the heart and blood vessels, resulting in a decrease in peripheral vascular resistance and a reduction in heart rate. Do not confuse Tenex (antihypertensive) with Xanax (antianxiety), Entex (Children’s Advil Cold), or Ten-K (potassium supplement). Rebound high blood pressure may occur but is less common than that which occurs with similar drugs. Maximum dose is 40 mg up to a child weighing 50 lbs, and 75 mg for a child weighing up to 75 lbs. Available forms: capsules (extended release) 200 mg, 300 mg; injection 25 mg/ml; oral concentrate 30 mg/ml. The oral route has an onset of 30 – 60 minutes with a duration of 4 – 6 hours; the oral (extended) also has an onset of 30 – 60 minutes with a duration with a duration of 10 – 12 hours; the rectal route has an onset greater than 1 hour with a duration of 3 - 4 hours. Nursing Considerations: If given with the following may see adverse effects: -Antacids – may inhibit the absorption of Thorazine (antipsychotic). John’s Wort (herb) may cause photosensitivity reactions – advise patient to avoid excessive sunlight exposure. It may not appear until months or years later and may disappear spontaneously or persist for life, despite stopping drug. In patients with risk factors for diabetes, obtain fasting blood glucose test results at baseline and periodically. It may not appear until months or years later and may disappear spontaneously or persist for life, despite stopping drug. Although the precise mechanism of action is unknown, most of these agents depress spinal polysynaptic reflexes. Uses: Musculoskeletal and Neurological Disorders associated with muscle spasms, hyper- reflexia, and hypotonia, including Parkinson’s, tetanus headaches, acute muscle spasms caused by trauma and inflammation (low back syndrome, strains, arthritis, and bursitis). They also may be useful in the management of Cerebral Palsy and Multiple Sclerosis.
This may be a factor in some settings order provera with american express, qualitative study of patients’ views on anxiety and depression though most studies find a low level of inappropriate prescribing found marked preferences regarding their perceived health and a high level of unmet need buy discount provera 5 mg. Certain patient groups may dence of ‘overtreatment’ (including inappropriate counselling purchase provera 5mg on line, be particularly reticent about starting or continuing psychotropic prescription of psychotropic medication, or specialist referral) in drug treatment. For example, in a United States study of beliefs 11% of individuals without a formal psychiatric diagnosis, but about psychotherapy and psychotropic drug treatment for an also found substantial rates of ‘under-treatment’ for individuals anxiety disorder which found few differences between diagnos- with the diagnoses of major depressive episode (49%) or gener- tic groups, coexisting depression was associated with more alised anxiety disorder (64%) [I] (Olsson et al. Another inves- of good response to, or poor tolerability of, previous tigation of perceived barriers to care suggested that difficulties in treatments [S] the continuing treatment of panic disorder were primarily admin- istrative, such as being uncertain where to seek help, worrying Baldwin et al. Pharmacological treatments in tine and venlafaxine have been associated with discontinuation symptoms after abrupt withdrawal [I(M)] (Baldwin et al. Antipsychotic drugs are often prescribed to patients with anxiety disorders, but the strongest evidence for benefit is restricted to acute treatment and prevention of relapse with quetiapine in gen- 12. The azapirone drug buspirone is efficacious in the acute erance and dependence can occur (especially in predisposed treatment of generalised anxiety disorder [I (M)] (Chessick et al. In generalised anxiety ● Remember that benzodiazepines can be effective in disorder, it is efficacious in relieving depressive symptoms of many patients with anxiety disorders [A], but recog- mild to moderate intensity [I (M)] (Stein et al. In generalised anxiety dis- problems (including anxiety, depression, and ‘stress’) indicates order and panic disorder, a typical treatment course consists of that the short-term (but not long-term) efficacy of counselling was approximately 16–20 h, up to half of which can be conducted by greater than that of standard general practitioner care, with or the patient in supervised ‘homework’ sessions, over a period of without antidepressant treatment [I (M)] (Bower et al. In social anxiety disorder a selling is less beneficial than longer-term treatment with other standard course should consist of up to 14 sessions of 90 min psychological interventions [I (M)] (Cape et al. In post-traumatic stress - have not been subject to extensive controlled investigations disorder, a standard course of psychological treatment might (Leichsenring, 2005; Lewis et al. The efficacy of psychological and pharmacological approaches is broadly similar in the acute treatment of anxiety Recommendations: general aspects of psychological disorders. In some studies, relapse rates are lower after an initial treatment response to cognitive therapy with exposure than after response to drug treatment. In most anxiety dis- and potential risks of specific psychological interven- orders (generalised anxiety disorder, social anxiety disorder, tions with patients before starting treatment [S] post-traumatic stress disorder, obsessive-compulsive disorder) it ● Ensure that psychological treatments are only deliv- is uncertain whether combining psychological and pharmaco- ered by suitably trained and supervised staff, able to logical treatments is associated with greater long-term benefit demonstrate that their clinical practice adheres to evi- than that which is seen with either treatment approach when dence-based treatment protocols [A] given alone. However, previous concerns that prescription of ● Remind patients that response to psychological treatment psychotropic drugs might reduce the efficacy of psychological is not immediate and that a prolonged course is usually treatment are probably unfounded: in some anxiety disorders sys- needed to maintain an initial treatment response [S] tematic reviews suggest that psychotropic drug administration ● Plan sequential steps in patient management rather can enhance the short-term efficacy of cognitive-behavioural than combining treatments from the start, as it is uncer- interventions. As with pharmacological approaches, it should be tain whether combining is associated with greater long- emphasised that response to psychological treatment is not term benefit [D] immediate; that transient worsening of symptoms can sometimes 12 Journal of Psychopharmacology 14. The role of self-help and Other complementary approaches include regular exercise and interventions drawing on meditation techniques. A system- complementary approaches in anxiety atic review indicates that exercise training reduces anxiety symp- disorders toms in sedentary patients with long-term medical conditions [I Patient preference and the often sub-optimal effects of ‘standard’ (M)] (Herring et al. Meditation and yoga practices are often advocated, as part of There have been relatively few randomised controlled trials the overall management of patients with anxiety disorders. Early of the efficacy and acceptability of self-help approaches under- systematic reviews found only minimal evidence for the effec- taken as individuals, and few studies have been conducted in tiveness of meditation therapy [I (M)] (Krisanaprakornit et al. However another systematic review indicated six randomised controlled trials found evidence for the efficacy that relaxation training (which often includes components of of self-help in primary care patients with mixed anxiety disor- meditation) is effective in reducing anxiety symptoms in non- ders, greater efficacy being seen with more detailed instruction in clinical and clinical groups [I (M)] (Manzoni et al. The the findings of two recent systematic reviews suggest that medi- findings of a systematic review of 21 studies in patients with tative therapies are effective in reducing anxiety symptoms depression or anxiety disorders suggest that guided self-help has (though their effect in anxiety disorders is uncertain) [I (M)] similar effectiveness to face-to-face psychotherapy [I (M)] (Chen et al. Costs of illness and cost- tiveness of a number of ‘phytomedicines’, including Passiflora effectiveness of treatment species extracts, Kava (Piper methysticum), and combinations of l-lysine and l-arginine (Lakhan and Vieira, 2010; Sarris Anxiety disorders are associated with a substantial economic bur- et al. There is no current den: both in health care systems (mainly direct costs of assessment, convincing evidence for the effectiveness of homoeopathic investigation, treatment and care), and in the wider society (includ- preparations in the treatment of patients with anxiety disor- ing premature mortality, unemployment, reduced productivity ders [I (M)] (Davidson et al. Using estimates to calculate the size patients with generalised anxiety disorder but have been with- of the population in the European Union that would be affected drawn in many countries due to potential hepatotoxic effects (69. Treatment costs account for a degree of functional impairment associated with generalised small proportion of the overall costs of health care, and it has been anxiety disorder is similar to that with major depression [I] argued that the increased costs of strategies to increase the recogni- (Wittchen et al. Patients with ‘co-morbid’ depression and tion and evidence-based treatment in patients that would otherwise generalised anxiety disorder have a more severe and prolonged remain undetected and untreated would be small, compared to the course of illness and greater functional impairment (Tyrer et al. However recognised as having a mental health problem, though not neces- there have been relatively few randomised controlled trials or sys- sarily as having generalised anxiety disorder [I] (Weiller et al. Acute treatment Investigations of the costs of illness and cost-effectiveness of The findings of systematic reviews [I (M)] (Baldwin et al. The cost- nificant differences in overall efficacy between active com- effectiveness of treatments for obsessive-compulsive disorder pounds. An early analysis of randomised controlled trials of has been investigated only rarely, with limited evidence for the acute treatment found an overall mean effect size of 0. It is uncertain whether antide- pressant drugs, pregabalin and benzodiazepines differ in their relative efficacy in reducing the severity of psychological or 16. The anxiety disorder findings of fixed-dose randomised placebo-controlled trials provide some evidence of a dose-response relationship for pre- 16. However it is often not recog- antidepressant, a post hoc pooled analysis of randomised pla- nised, possibly because only a minority of patients present cebo-controlled trials with pregabalin indicate that it is effica- with anxiety symptoms (most present with physical symp- cious in reducing depressive symptom severity in patients with toms), and doctors tend to overlook anxiety unless it is a pre- mild to moderate intensity of depressive symptoms [I (M)] senting complaint [I] (Munk-Jorgensen et al. Comparative efficacy of psychological, Recommendations: managing patients with general- pharmacological, and combination ised anxiety disorder treatments Detection and diagnosis Pharmacological or psychological treatments, when delivered sin- ● Become familiar with the symptoms and signs of gen- gly, have broadly similar efficacy in acute treatment [I (M)] eralised anxiety disorder [S] (Bandelow et al. Further management after non- ing treatment, as pharmacological and psychological response to initial treatment approaches have broadly similar efficacy in acute treat- Many patients do not respond to first-line pharmacological or ment [S] psychological interventions. In acute treatment, the combination of psychotherapy with antidepressants is superior to psychotherapy or an antidepressant, when either is given alone (Furukawa et al. Further management after non- some anticonvulsants (gabapentin, sodium val- proate) [A] response to initial treatment ○ psychological: cognitive-behaviour therapy [A] Many patients do not respond to first-line pharmacological or ● Avoid prescribing propranolol, buspirone and bupro- psychological interventions. The findings of a meta-analytic review of 33 randomised controlled ● Continue drug treatment for at least six months in treatment studies indicate that exposure-based therapies (particu- patients who have responded to treatment [A] larly those involving in vivo exposure) are more effective than ● Use an approach that is known to be efficacious in pre- other psychological interventions: effectiveness being seen venting relapse [S] regardless of the nature of the specific phobia, and being some- ● Monitor effectiveness and acceptability regularly over what greater with multiple rather than single sessions [I (M)] the course of treatment [S] (Wolitzky-Taylor et al. It is When initial treatments fail unclear whether concomitant use of benzodiazepines enhances or reduces the efficacy of behavioural approaches. Management of social anxiety Specific fears of objects, animals, people or situations are wide- disorder (also known as social spread in children, adolescents and adults, but only a minority of affected individuals reach the full diagnostic criteria for specific phobia) phobia. Many affected individuals have multiple through the use of screening questionnaires in psychologically fears, whose presence is associated with an earlier onset, greater distressed primary care patients [I] (Donker et al. Longer term treatment mere ‘shyness’ but can be distinguished from shyness by the higher levels of personal distress, more severe symptoms and The findings of acute treatment studies indicate that the propor- greater impairment [I] (Burstein et al. A post hoc analysis of the tions) can be substantially impaired [I] (Aderka et al. There are strong, domised placebo-controlled relapse-prevention studies in and possibly two-way, associations between social anxiety dis- patients who have responded to previous acute treatment reveal a order and dependence on alcohol and cannabis [I] (Buckner significant advantage for staying on active medication (clonaze- et al. The potential efficacy of tricyclic antidepressants is findings of small randomised placebo-controlled studies suggest unknown. A double-blind randomised con- trolled studies of acute treatment and most reveal no significant trolled dosage escalation trial found no advantage for increas- differences in overall efficacy or tolerability between active com- ing to a higher daily dosage (120 mg) of duloxetine, when pounds. The 12-month prevalence of post-traumatic ment [A] stress disorder is estimated to be 1. Suicidal ● Advise the patient that treatment periods of up to 12 thoughts are common but the increased risk of completed suicide weeks may be needed to assess efficacy [A] is probably due to the presence of comorbid depression [I (M)] Longer-term treatment (Krysinska and Lester, 2010). Post-traumatic stress disorder is associated with increased use of health services, but is often not ● Use an approach that is known to be efficacious in pre- recognised in primary or secondary care [I] (Liebschutz et al. Diagnosis can be established through eliciting the history ● Continue drug treatment for at least six months in of exposure to trauma (actual or threatened death, serious injury, patients who have responded to treatment [A] or threats to the physical integrity of the self or others); with a ● Consider cognitive therapy with exposure as this may response of intense fear, helplessness or horror; and the presence reduce relapse rates better than drug treatment [A] of ‘re-experiencing symptoms’ (such as intrusive recollections, ● Consider cognitive therapy after response to drug treat- flashbacks or dreams); avoidance symptoms (such as efforts to ment, in patients with a high risk of relapse [D] avoid activities or thoughts associated with the trauma); and ● Monitor effectiveness and acceptability regularly over hyper-arousal symptoms (including disturbed sleep, hypervigi- the course of treatment [S] lance and an exaggerated startle response).
This is hydrolyzed and forms glycerol cost of provera, which is phosphorylated and Chemistry/Apply principles of basic laboratory forms glycerol-3-phosphate buy cheap provera line. This is oxidized by procedures/Enzymes/1 glycerophosphate oxidase buy generic provera 2.5 mg on-line, yielding hydrogen 78. Glutamate dehydrogenase and drugs that function as cholinesterase inhibitors Chemistry/Correlate clinical and laboratory and the serum assay is used to presumptively data/Enzymes/2 identify cases of insecticide poisoning. Levels of pseudocholinesterase are decreased in patients with liver disease as a result of depressed synthesis. In cirrhosis and hepatoma, there is a 50%–70% reduction in serum level and a 30%–50% reduction in hepatitis. Elastase-1 is a pancreatic digestive enzyme that breaks down connective tissue protein. C 5‘-Nucleotidase is increased primarily in obstructive liver disease and liver cancer. Glutamate dehydrogenase is increased in necrotic liver diseases along with transaminases, but because of its distribution it is elevated to a greater extent in toxic hepatitis and therefore is useful as a marker for halothane (anesthesia) toxicity. Aldolase is found in all tissues and is increased in many conditions including myocardial infarction, viral hepatitis, and myelocytic leukemia. Persons with the deﬁciency are prone to a hemolytic episode upon exposure to certain oxidative drugs and fava beans and as a result of infections. Which of the following hormones is often Answers to Questions 1–4 decreased by approximately 25% in the serum of pregnant women who have a fetus with Down 1. Estradiol (E2) for the gestational age in a pregnancy associated Chemistry/Correlate laboratory data with physiological with Down syndrome. Select the hormone which when elevated is potassium, and other electrolytes by hemodilution. It associated with galactorrhea, pituitary adenoma, is suspected when urine osmolality is higher than and amenorrhea. D Serum prolactin may be increased from hypothalamic Chemistry/Correlate clinical and laboratory dysfunction or pituitary adenoma. A Multiple-endocrine neoplasia syndrome is inherited least two endocrine organs as an autosomal dominant disease involving excess B. Insulinoma is always present when the pituitary production of hormones from several endocrine is involved glands. It is inherited as an autosomal recessive disorder of at least two glands, including the pituitary, adrenal D. The parathyroid elevated at least 10-fold gland is the organ most commonly involved, and in those patients an elevated Cai is an early sign. The Chemistry/Correlate clinical and laboratory data/ pancreas is the next most frequently involved organ, Endocrine/2 but the hormone most commonly oversecreted 6. E2 is used to Chemistry/Apply knowledge of fundamental biological evaluate both ovarian function and menstrual cycle characteristics/Estrogen/1 dysfunction. Both are usually increased when there is pituitary serum peak 1–2 days prior to ovulation and urine adenoma peak 20–44 hours before ovulation. When pituitary adenoma is the cause of decreased estrogen production, an increase of which 8. A Prolactinoma can result in anovulation because hormone is most frequently responsible? Which set of results is most likely in an adult male with primary testicular failure? Chemistry/Correlate clinical and laboratory data/ Endocrine/2 284 Chapter 5 | Clinical Chemistry 10. When should progesterone be measured when Answers to Questions 11–14 evaluating an adult female for anovulation? During the ﬁrst 7 days of the menstrual cycle estrogen, and prolactin to evaluate female infertility C. At the end of the menstrual cycle corpus luteum and levels are very low during the early follicular phase of the cycle. A female with severe excessive pubic and facial hair indication that ovulation occurred. Low progesterone growth (hirsutism) should be tested for which of at midcycle indicates that ovulation did not occur. Testosterone and dehydroepiandrosterone sulfate levels of ovarian-derived testosterone. It will also occur Chemistry/Correlate laboratory and clinical data/ as a consequence of Cushing’s syndrome and mild Fertility testing/2 congenital adrenal hyperplasia. Which set of results is most likely in a female with 17 α-hydroxyprogesterone can help identify those hypogonadotropic ovarian failure? Decreased prolactin and estrogen useful in identifying those rare cases where the cause D. B Hypogonadotropic ovarian failure is the result of Fertility testing/2 pituitary dysfunction. Te onset of menopause is usually associated with levels of prolactin as in prolactinoma, since prolactin what hormone changes? Deﬁciency is documented by registering a subnormal response to two stimulating agents. Some patients will require a glucose suppression establish a diagnosis of acromegaly because various test to establish a diagnosis metabolic and nutritional factors can cause an C. The distal collecting tubule of the nephron Chemistry/Correlate clinical and laboratory data/ reabsorbs less bicarbonate as well as phosphate, Endocrine/2 resulting in acidosis. The biological activity of the hormone resides Chemistry/Apply principles of special procedures/ in the N-terminal portion of the polypeptide, but Hormone assays/1 the hormone is rapidly degraded and produces N-terminal, middle, and C-terminal fragments. Which of the following is most often elevated in Answers to Questions 19–21 hypercalcemia associated with malignancy? Which of the following statements regarding Calcitonin is a hormone produced in the medulla of adrenal cortical dysfunction is true? Patients with Cushing’s syndrome usually have calcitonin levels do not greatly inﬂuence the serum hyperkalemia calcium. Cushing’s syndrome is associated with glucose diagnose medullary thyroid cancer, which produces intolerance very high serum levels. Addison’s disease is caused by elevated levels of and abnormal levels have pronounced eﬀects on cortisol carbohydrate and lipid metabolism. Cortisol is a 21-carbon steroid with a dihydroxyacetone group at Chemistry/Correlate clinical and laboratory data/ C17 and hydroxyl group at C11 that account for its Adrenal/2 glucocorticoid potency. Plasma and urinary cortisol measurements are used to diagnose most types of adrenocortical dysfunction.
Presented alone buy generic provera line, an epitope is not sufficient to stimulate an immu- nological response purchase provera cheap. Instead responsiveness is stimulated by epitopes con- Kayser discount provera 2.5 mg, Medical Microbiology © 2005 Thieme All rights reserved. This is why the epitope component of an antigen is terminologically distinguished from its macromolecular carrier; together they form an immunogen. These cells can only recognize protein 2 antigens that have been processed by host cells and presented on their sur- face. The T-cell receptors recognize antigen fragments with a length of 8–12 sequential amino acids which are either synthesized by the cell itself or pro- duced subsequent to phagocytosis and presented by the cellular transplan- tation antigen molecules on the cell surface. The T cells can then complete their main task—recognition of infected host cells—so that infection is halted. Our understanding of the immune defense system began with studies of infectious diseases, including the antibody responses to diphtheria, dermal reactions to tuberculin, and serodiagnosis of syphilis. Characteriztion of pathological antigens proved to be enormously difficult, and instead erythro- cyte antigens, artificially synthesized chemical compounds, and other more readily available proteins were used in experimental models for more than 60 years. Major breakthroughs in bacteriology, virology, parasitology, biochem- istry, molecular biology, and experimental embryology in the past 30–40 years have now made a new phase of intensive and productive research pos- sible within the field of immune defenses against infection. The aim of this chapter on immunology, in a compact guide to medical microbiology, is to present the immune system essentially as a system of defense against in- fections and to identify its strengths and weaknesses to further our under- standing of pathogenesis and prevention of disease. The Immunological Apparatus & The immune system is comprised of various continuously circulating cells (T and B lymphocytes, and antigen-presenting cells present in various tis- sues). T and B cells develop from a common stem cell type, then mature in the thymus (Tcells) or the bone marrow (B cells), which are called primary (or central) lymphoid organs. The antigen-specific activation of B and/or T cells in- volves their staggered interaction with other cells in a contact-dependent manner and by soluble factors. They secrete antibodies into the blood (soluble antibodies) or onto mucosal surfaces once they have fully matured into plasma cells. Antibodies recognize Kayser, Medical Microbiology © 2005 Thieme All rights reserved. Chemically, B-cell receptors are globulins (“immunoglobulins”) and comprise an astounding variety of specific types. Despite the division of immunoglobulins into classes and subclasses, they all share essentially the same structure. Naive Tcells circulate through the blood, spleen, and other lymphoid tissues, but cannot leave these com- partments to migrate through peripheral nonlymphoid tissues and organs unless they are activated. Self antigens (autoantigens), presented in the thy- mus and lympoid tissues by mobile lymphohematopoietic cells, induce T-cell destruction (so-called negative selection). Antigens that are expressed only in the periphery, that is outside of the thymus and secondary lymphoid or- gans, are ignored by T cells; potentially autoreactive T cells are thus directed against such self antigens. New antigens are first localized within few lym- phoid tissues before they can spread systemically. These must be present in lymphoid tissues for three to five days in order to elicit an immune response. An immune response can be induced against a previously ignored self antigen that does not normally enter lymphoid tissues if its entry is induced by cir- cumstance, for instance, because of cell destruction resulting from chronic peripheral infection. It is important to remember that induction of a small number of T cells will not suffice to provide immune protection against a pathogen. This can be better understood by examining how the individual com- ponents of the immune response function. The human immunological system can be conceived as a widely dis- tributed organ comprising approximately 1012 individual cells, mainly lym- phocytes, with a total weight of approximately 1kg. Leukocytes arise from pluripotent stem cells in the bone marrow, then differentiate further as two distinct lineages. The myeloid lineage constitutes granulocytes and mono- cytes, which perform important basic defense functions as phagocytes (“scavenger cells”). The lymphoid lineage gives rise to the effector cells of the specific immune response, T and B lymphocytes. These cells are con- stantly being renewed (about 106 new lymphocytes are produced in every minute) and destroyed in large numbers (see Fig. T and B lym- phocytes, while morphologically similar, undergo distinct maturation pro- Kayser, Medical Microbiology © 2005 Thieme All rights reserved. The antigen-independent phase of lymphocyte differentiation takes place in the so-called primary lymphoid organs: T lymphocytes mature in the thymus and B lymphocytes in the bursa fabricI (in birds). Although mammals have no bursa, the term B lymphocytes (or B cells) has been retained to distinguish these cells, with their clearly distinct 2 functions and maturation in the bone marrow, from T lymphocytes, which mature in the thymus (Table 2. In addition to their divergent differentia- Maturation of B and T cells Primary (central) lymphoid organs Secondary (peripheral) lymphoid organs Antigen-independent Antigen-dependent Progenitor Precursor B Immature Mature Activated Blast Plasma cell B (pro-B) cell (pre-B) cell B cell IgM B cell B cell IgD B cell µ µ B cells µ λ5/V B λ or κ IgM IgM pre 1,2 IgD IgM Bone marrow αβ αβ Effector T Stem cell ρTα Mature T cells β β (Te) cells T cells αβ Activation in secondary Immature T cells ± selection lymphoid organs (via contact and/ Thymic cortex Thymic medulla or interleukins) Fig. Stem cells that remain in the bone marrow develop into mature B cells via several anti- gen-independent stages; including the k5Vpre-B cell stage, and pre-B cells with a special k5 precursor chain. Antigen contact within secondary lymphoid or- gans can then activate these cells, finally causing them to differentiate into anti- body-secreting plasma cells. From here, these single positive T cells can emigrate to peripheral secondary lymphoid organs, where they may become activated by a combination of antigen contacts, secondary signals, and cytokines. They manifest contrasting response patterns to cyto- kines, and display a marked preference to occupy different compartments of lymphoid organs. The antigen-dependent differentiation processes which leads to T and B cell specialization, takes place within the secondary lym- phoid organs where lymphocytes come into contact with antigens. As a general rule the secondary lymphoid organs contain only mature T and B cells, and comprise encapsulated organs such as the lymph nodes and spleen, or non-encapsulated structures which contain lymphocytes and are associated with the skin, mucosa, gut, or bronchus (i. Together, the primary and secondary lymphoid organs ac- count for approximately 1–2% of body weight. The B-Cell System & B lymphocytes produce antibodies in two forms; a membrane-bound form and a secreted form. Following antigen stimulation, B lymphocytes differentiate into plasma cells, which secrete antibodies exhibiting the same antigen specifi- city as the B-cell receptor. This system is characterized as humoral immu- nity, due to this release of receptors into the “humoral” system which constitutes vascular contents and mucous environments. Usage subject to terms and conditions of license 50 2 Basic Principles of Immunology system also contains non-specific defense mechanisms, including the com- plement system (see “Immune response and effector mechanisms,” p. These immunoglobulins comprise a number of classes and subclasses, as well as numerous different specificities, but share a common structure 2 (Fig. The five corresponding im- munoglobulin classes are designated as IgM, IgD, IgG, IgA, or IgE, depending on which type of heavy chain they use (Fig. A special characteristic of the immunoglobulin classes IgA and IgM is that these comprise a basic monomeric structure that can be doubled or quintupled (i. The upper half of the figure shows the intact monomer consisting of two L and two H chains.
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