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Low doses of tivity of the subject super p-force 160 mg line erectile dysfunction medication injection, any prior cardiovascular and baro- epinephrine will dilate the blood vessels; larger doses receptor pathology order super p-force cheap erectile dysfunction 55 years old, and the presence of other drugs that will constrict them buy genuine super p-force online erectile dysfunction medicine reviews. Although several factors can inﬂuence the ﬂow of In a normal resting subject who is receiving no blood through the coronary vessels, the most important drugs, there is a moderate parasympathetic tone to the of these is the local production of vasodilator metabolites heart, and sympathetic activity is relatively low. The that results from stimulation-induced increased work by ventricular muscle receives little, if any, parasympathetic the heart. As the blood pressure rises in response to the coronary vascular beds do not play a major role in norepinephrine, the baroreceptor reﬂex is activated, determining the vasodilator effects of the administra- parasympathetic impulses (which are inhibitory) to the tion of epinephrine or norepinephrine. Heart rate is slowed so much that the direct effect of norepinephrine to in- Effects on the Intact Cardiovascular System crease the rate is masked and there is a net decrease in An increase in sympathetic neuronal activity causes an rate. Under the conditions described, however, the im- increase in heart rate (positive chronotropic effect, or pact of the reﬂex on the ventricles is very slight because tachycardia) and an increase in cardiac contractile force there is no parasympathetic innervation and the preex- (positive inotropic effect) such that the stroke output is isting level of sympathetic activity is already low. Cardiac output, which is a function of rate ther decrease in sympathetic activity therefore would and stroke output, is thus increased. The reﬂex nature of the bradycardia induced by An increase in sympathetic tone constricts blood parenterally administered norepinephrine can readily vessels in most vascular beds and therefore causes a net be demonstrated by administration of atropine, a choli- increase in total peripheral resistance. Atropine abolishes the com- thetic tone increases neural release of norepinephrine pensatory vagal reﬂexes. Under conditions of vagal and its interaction both with -adrenoceptors on car- blockade, the direct cardiac stimulatory effects of nor- diac cells and with -adrenoceptors on vascular smooth epinephrine are unmasked. As a consequence, the systolic and diastolic dia, an increase in stroke volume, and as a consequence, blood pressures are elevated. Epinephrine Norepinephrine A small dose of epinephrine causes a fall in mean Norepinephrine, administered to a normotensive and diastolic pressure with little or no effect on systolic adult either subcutaneously or by slow intravenous in- pressure. The baroreceptor may decrease, remain unchanged, or increase slightly, reﬂexes are discussed in detail in Chapter 9. The cardiac effects of epinephrine are due to its ac- (2) The reﬂex initiated is inhibitory, that is, opposite to tion on -adrenoceptors in the heart. Heart rate is given in beats per minute, blood pressure in millimeters of mercury, and peripheral resistance in arterial blood pressure. The endothelium can modulate Slow intravenous infusion of therapeutic doses of both vasodilation and vasoconstriction through its ability isoproterenol in humans produces a marked decrease in to locally synthesize and release vasodilators such as nitric total peripheral resistance, owing to the predominance oxide, endothelium-derived hyperpolarizing factor, and of vasodilation in skeletal muscle vascular beds. The depressor action of isoproterenol is more Stimulation of 2-adrenoceptors located on the endothe- pronounced than that of epinephrine because isopro- lial cells in certain vascular beds (such as the coronary ar- terenol causes no vasoconstriction, whereas epinephrine tery) results in the release of nitric oxide and vasodilation. Systolic blood pressure may In any blood vessel, the ﬁnal integrated response to remain unchanged or may increase. When an increase in either neuronally released norepinephrine or to circu- systolic blood pressure is seen, it is due to the marked in- lating epinephrine probably depends on the relative crease in cardiac output produced by isoproterenol. This is ate constriction of vascular smooth muscle, while pre- partly due to its ability to decrease mean blood pres- junctional and endothelial 2-adrenoceptors mediate sure, which then reﬂexively diminishes vagal activity, vasodilation. Effects on Vascular Smooth Muscle Postjunctional 1-adrenoceptors are always found in Effects on Nonvascular Smooth Muscle veins, arteries, and arterioles. Activation of these recep- tors results in the entry of extracellular calcium through In general, the responses to administered catechol- receptor-operated channels and in the release of intra- amines are similar to those seen after sympathetic nerve cellularly stored calcium; this is brought about through stimulation and depend on the type of adrenoceptor in the participation of the inositol triphosphate second- the muscle. Most of these are mediated through an and isoproterenol through their interaction with 2- interaction with -adrenoceptors. Epinephrine and tent bronchodilators, while norepinephrine has a rela- isoproterenol in therapeutic doses increase oxygen con- tively weak action in this regard (see Chapter 39). Endogenous epinephrine se- Smooth muscle of the gastrointestinal tract is gener- creted by the adrenal medulla in response to stress such ally relaxed by catecholamines, but this may depend on as exercise increases blood levels of glucose, lactic acid, the existing state of muscle tone. Catecholamines ap- glycogenolysis, gives rise to glucose, which readily en- pear to produce relaxation of the gut through an action ters the circulation; isoproterenol produces relatively on 2-adrenoceptors on ganglionic cells. Administration of both - and these receptors reduces acetylcholine release from -adrenoceptor blocking agents is necessary for com- cholinergic neurons. Contraction of tal muscle glycogenolysis, followed by epinephrine the sphincters occurs through an action on 1-adreno- and norepinephrine. Epinephrine and norepinephrine cause enzyme glucose-6-phosphatase, which catalyzes the dilation of the pupil (mydriasis) by contracting the dila- conversion of glucose-6-phosphate to glucose. The release of free fatty acids from adipose tissue Uterine muscle contains both - and -adrenocep- (lipolysis) is mediated through 3-adrenoceptors. Iso- tors, which mediate contraction and relaxation, respec- proterenol is the most potent agonist, followed by epi- tively. During the last stage of preg- nancy and during parturition, epinephrine inhibits the The catecholamines can play an important role in the uterine muscle, as does isoproterenol; norepinephrine short-term regulation of plasma potassium levels. Stimulation of hepatic -adrenoceptors will result in the The detrusor muscle (which contains 2-adrenocep- release of potassium from the liver. In contrast, stimula- tors) in the body of the urinary bladder is relaxed by tion of 2-adrenoceptors, particularly in skeletal muscle, epinephrine and isoproterenol. Dopamine is a naturally occurring catecholamine; it is Since these compounds do not easily cross the blood- the immediate biochemical precursor of the norepi- brain barrier, the mechanism of their stimulatory effects nephrine found in adrenergic neurons and the adrenal is not clear. Dopamine is a unique adrenomimetic drug in that it exerts its cardiovascular actions by (1) releasing norepi- Metabolic Effects nephrine from adrenergic neurons, (2) interacting with The catecholamines, primarily epinephrine and isopro- -and 1-adrenoceptors, and (3) interacting with spe- terenol, exert a number of important effects on meta- ciﬁc dopamine receptors. Its use promotes an beds with little effect on other blood vessels or on the increase in the outﬂow of aqueous humor. The vasodilation produced by dopamine is not nephrine administration will decrease the ﬁltration an- antagonized by the -adrenoceptor blocking agent pro- gle formed by the cornea and the iris, its use is con- pranolol but is antagonized by haloperidol and other traindicated in angle-closure glaucoma; under these dopamine receptor–blocking agents. Stimulation of the D1-receptor, The vasoconstrictor actions of epinephrine and nor- which is present on blood vessels and certain other pe- epinephrine have been used to prolong the action of lo- ripheral sites, will result in vasodilation, natriuresis, and cal anesthetics by reducing local blood ﬂow in the re- diuresis. Norepinephrine is infused intravenously to com- produces hypotension, bradycardia, and regional va- bat systemic hypotension during spinal anesthesia or sodilation (e. The kidney appears other hypotensive conditions in which peripheral resist- to be a particularly rich source for endogenous ance is low, but it is not used to combat the hypotension dopamine in the periphery. In shock, marked sympa- The infusion of moderately higher concentrations of thetic activity is already present, and perfusion of or- dopamine increases the rate and contractile force of the gans, such as the kidneys, may be jeopardized by norepi- heart and augments the cardiac output. In contrast to to inadequate cardiac output (cardiogenic shock), isoproterenol, which has a marked effect on both the which may be due to myocardial infarction or conges- rate and the contractile force of the heart, dopamine has tive heart failure. The septic shock, since renal circulation is frequently com- advantage of this greater inotropic than chronotropic promised in this condition. An advantage of using effect of dopamine is that it produces a smaller increase dopamine in the treatment of shock is that its in- in oxygen demand by the heart than does isoproterenol. Adverse Effects At still higher concentrations, dopamine causes -adrenoceptor-mediated vasoconstriction in most vas- Because they increase the force of the heartbeat, all cular beds and stimulates the heart. Palpitations produced by epinephrine and dopamine reaching the tissue is high enough, vasocon- isoproterenol are accompanied by tachycardia, whereas striction of the renal and mesenteric beds also occurs. Large doses of isoproterenol can produce such actions on bronchial smooth muscle, blood vessels, and excessive cardiac stimulation, combined with a decrease the heart. Epinephrine is also useful for the treatment in diastolic blood pressure, that coronary insufﬁciency of allergic reactions that are due to liberation of hista- may result. It also may cause arrhythmias and ventricu- mine in the body, because it produces certain physio- lar ﬁbrillation. It is also employed in ophthalmology as a mydri- A number of adrenomimetic amines are not cate- atic agent. Some of these are directly acting amines to patients with closed-angle glaucoma before iridec- that must interact with adrenoceptors to produce a re- tomy, since further increases in intraocular pressure sponse in effector tissues.
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What information (signs order cheapest super p-force erectile dysfunction normal age, symptoms purchase 160mg super p-force with amex erectile dysfunction doctors in south jersey, laboratory values) indi- Deferred cates the presence and severity of rheumatoid arthritis? What clinical and laboratory parameters are necessary to evaluate See Table 96-1 the patient’s drug therapy? What information should be provided to the patient to enhance í Chest X-Ray adherence cheap super p-force 160mg otc erectile dysfunction doctor in los angeles, ensure successful therapy, and minimize adverse No fluid, masses, or infection; no cardiomegaly effects? Guidelines for the management of rheumatoid Donald Abernathy is a 73-year-old man who presents to the arthritis: 2002, Update. Etanercept therapy complaining of increasing pain in his lower back, hips, and right in rheumatoid arthritis. Therapeutic effect of mg tablets, two tablets four times daily, and has been taking more the combination of etanercept and methotrexate compared with each than prescribed over the last few weeks. He has infliximab and methotrexate therapy for early rheumatoid arthritis: a been adherent to all other drug therapies. A multicentre, double blind, on excess weight and developed many medical problems that are randomized, placebo controlled trial of anakinra (Kineret), a recombi- frustrating him. Sulfa—hives • Design an appropriate pharmacotherapeutic regimen for treat- Egg products ing osteoarthritis, taking into account a patient’s other medical problems and drug therapy. What feasible pharmacotherapeutic alternatives are available stool in rectal vault for treatment of this patient’s osteoarthritis? What drug, dosage form, schedule, and duration of therapy are rotation >45°; both hips tender to palpation; right knee (+) crepi- best for treating this patient’s osteoarthritis? What clinical and laboratory parameters are necessary to evaluate ally except for slightly diminished Achilles reflexes bilaterally; no the therapy for achievement of the desired therapeutic outcome focal deficits; gait impaired secondary to hip and knee pain. What information should be provided to the patient to enhance adherence, ensure successful therapy, and minimize adverse effects? If not, • Recognize major risk factors for developing gout in a given pa- what is an appropriate next step of treatment? Which form of glu- • Develop a pharmacotherapeutic plan for a patient with acute cosamine is best to suggest to patients? The patient tells you that one time his friend received an injection into his knee that really helped his arthritis. When should intra- • Identify patients in whom maintenance therapy for gout and articular injections be considered, and what are some of their hyperuricemia is warranted. Patients whose arthritis is poorly or inadequately controlled often turn to alternative, homeopathic, or herbal remedies for relief. Identify one site that you think pro- Nathan Vance is a 66-year-old man with a history of dyslipidemia vides misleading or potentially dangerous information to patients. He relates no trauma or injury systematic approach to assessing and treating pain in order to to the ankle and has not exerted himself more than usual in the achieve total (or near-total) pain relief, avoid wasting resources, and recent past. Glucosamine, chondroitin sulfate, Simvastatin and atorvastatin (both caused severe muscle aches, and and the two in combination for painful knee osteoarthritis. He relates feeling “hot and flushed” occasionally after taking his niacin, but this has not been a major problem for him. Should chronic treatment to decrease the patient’s serum uric Clear to auscultation bilaterally, symmetric movement with inspira- acid level be initiated at this time? Considering the patient’s information, what drug, dosage form, schedule, and duration of therapy are best in this case? Joint is exquisitely painful with Patient Education patient relating the pain as currently a 10/10 (on a 1–10 scale with 6. What information should be provided to the patient to enhance “1” being no pain and “10” being the worse pain the patient has ever adherence, ensure successful therapy, and to avoid adverse effects? After consultation with you, í Labs the patient’s physician decides against maintenance therapy to Na 138 mEq/L Hgb 15. Primary presentation of acute gouty arthritis may be most appropriate, because it has been shown to signifi- cantly decrease serum uric acid levels? List antihyperuricemic agents that are available in the United States and their relative advantages and disadvantages. Fenofibrate enhances clinical endpoint for discontinuing the drug, as these side effects tend urate reduction in men treated with allopurinol for hyperuricaemia to occur prior to the more severe adverse effects of colchicine- and gout. Other ocular history includes severe myopia since child- After completing this case study, students should be able to: hood, history of dry eyes, and history of contact lens wear. Depression as a consequence of chronic open-angle glaucoma and worsening of vision after completion of his PhD program • Select and recommend agents from different pharmacologic class- S/P ultrasonic renal lithotripsy secondary to nephrolithiasis associ- es when indicated and provide the rationale for drug selection. Drank four cans of beer per day for 3 years during postgrad- • Explain and discuss possible adverse drug reactions with pa- uate study. Comparison of the retina in a patient with a healthy optic nerve (left) and in a patient with glaucoma and a large cup with a disc hemorrhage, typical of chronic open-angle glaucoma (right). No cataracts eyes; conjunctiva without injection; normal tear break-up, did not stain with fluorescein; cornea clear and smooth; anterior 4. Depression associated with chronic open-angle glaucoma without neovascularization or abnormality; no mass/nodules; í Plan filtering bleb is visible at 11 o’clock meridian. What information (signs, symptoms) indicates the presence or tone, and sensation are intact bilaterally. Are phosphodiesterase-5 inhibitors such as sildenafil safe for Sensation was intact and symmetric to pinprick, proprioception, and patients with high intraocular pressure? What clinical and laboratory parameters are necessary to evaluate • Classify a patient’s allergic rhinitis based on the signs and the therapy for achievement of the desired therapeutic outcome symptoms of the disease. What information should the patient receive about the disease of rhinitis with respect to efficacy and safety. What is the mechanism of action of these antimetabolites in tra- beculectomy pressure-lowering surgery? Perform a literature search and explain the rationale for using í Chief Complaint nimodipine and pentoxifylline in advanced open-angle glau- “My nose is stopped up and I can’t sleep at night. Compare the advantages and disadvantages of using this always tired, and now my eyes are itchy and watery all the time. Compliance and persistency in glaucoma follow-up symptoms have occurred off and on since she was a child, worsen- treatment. Response of filtered eyes to but she does have an occasional nonproductive cough that gets digital ocular pressure. A randomized double-masked Anterior cruciate ligament reconstruction at age 16 crossover study comparing latanoprost 0. J Ocul Phar- with moderate persistent asthma, and sister age 14, with allergic macol Ther 2003;19:37–44. She drinks 5 or 6 Perennial rhinitis with seasonal exacerbations: Discontinue butter- drinks once or twice a week when she goes out. Last August (about 8 months ago) Angele started attending the State University where she is a nursing major. Angele claims she is not sexually active but is considering having intercourse with her boyfriend of 7 months. What feasible pharmacotherapeutic alternatives are available is continually rubbing her nose and eyes. What clinical and laboratory parameters are necessary to evaluate the therapy for achievement of the desired therapeutic outcome No lymphadenopathy or thyromegaly and to detect or prevent adverse effects?
Agitation and confusion buy 160mg super p-force disease that causes erectile dysfunction, including visual Ergot derivatives (cabergoline order 160 mg super p-force fast delivery erectile dysfunction relationship, pergolide discount 160mg super p-force with mastercard erectile dysfunction treatment options in india, lisuride, hallucinations, may occur but it may be difficult to decide bromocriptine). Mental changes nists are now not preferred because of their high rate of are particularly likely in the elderly, especially when there is unwanted effects. If acute confusion occurs, other can cause fibrosis of internal organs after chronic exposure, Parkinson’s drugs that cause confusion – antimuscarinics, leading to serious complications (below). Alternatively, the anticholin- class; the former has the advantage of being very long acting esterase rivastigmine, or atypical neuroleptics such as que- (a t½ of more than 80 h), allowing a once-daily (or even tiapine or clozapine, may be of benefit. Additionally, cardiac valve Levodopa antagonises the effects of antipsychotics fibrosis may result in valvular incompetency, e. Consequently, patients who previously received er- got derivatives are now treated with non-ergot derivatives. In These mimic the effects of dopamine, the endogenous ag- those patients who require ergotamine dopamine agonists onist, which stimulates both of the main types of dopa- (because non-ergotamine equivalents may be less effective), mine receptor, D1 and D2 (coupled respectively to screening for potential complications is required, e. The D2recep- measuring plasma creatinine and performing echocardio- tor is the principal target in Parkinson’s disease, although grams 6-monthly. The main advantage of dopamine agonists Bromocriptine is a D2-receptor agonist and a weak relative to levodopa is that they do not result in significant a-adrenoceptor antagonist. It is commonly used to sup- motor fluctuations or dyskinesias, which may relate to their press the production of prolactin in patients with pro- longer t½, and to the fact that they are not dependent upon lactinomas (pituitary tumours) but now only rarely for pre-synaptic conversion. Whether they also protect dopa- Parkinson’s disease because nausea, vomiting and postural minergic neurones by sparing the levodopa dose, and hypotension are more prominent than with more modern therefore reducing levodopa-induced oxidative damage, dopamine agonists. These drugs are currently preferred as 31 first-line therapy in newly diagnosed patients under the Notethatdopaminecauseshypotension,whereasfurthermetabolismof levodopa to adrenaline/epinephrine and noradrenaline/norepinephrine age of 70 years old. Furthermore, psycho- infusion is also the preferred administration method for sis32 or confusion (unwanted effects of all dopamine dyskinetic patients. Overdose causes respiratory depression, started at low dose and increased over weeks or months, while naloxone antagonises its action. Autoimmune- daily administration but formulations that allow once- mediated haemolytic anaemia is a rare complication in pa- daily administration are available. The dopamine agonist tients taking concurrent levodopa, and their blood counts rotigotine can be used daily as a transdermal patch, and should be monitored. The enzymes exist in two principal forms, including punding, hypersexuality, gambling, eating A and B, defined by specific substrates, some of which can- binges and compulsive shopping. The iours may be more likely in Parkinson’s disease patients, in- therapeutic importance of recognising these two forms dependent of a treatment effect, due to a dysregulated arises because they are to some extent present in different dopamine-prefrontal reward system. Its cially tyramine, which may then act systemically as sympa- main use is in patients with advanced disease under thomimetics (causing the so-called hypertensive ‘cheese reaction’37). Alternatively, patients can re- advantage over selegiline in not producing amfetamine me- ceive apomorphine by continuous subcutaneous infusion tabolites, which are believed to be part of the reason for 32 35Domperidone is preferred as it does not cross the blood–brain barrier, This unwanted effect can be predicted from the fact that dopamine antagonists are used as antipsychotics. Determination of therapeutic and adverse effects is a function of selectivity of the inhibitor and the tissue location of the enzyme. Furthermore, two trials39 1 in 13 000 cases, thereby necessitating fortnightly screen- of rasagiline have suggested that patients who take this ing blood tests. Their use originated when hyoscine was given to one of the principal enzymes responsible for the metabo- parkinsonian patients in an attempt to reduce sialorrhoea lism of dopamine, and so prolongs the action of levodopa. These include benzhexol quent levodopa doses are used (typically at 3–4-hourly in- (trihexyphenidyl), orphenadrine, benzatropine, procycli- tervals), by providing a more predictable and stable dine, biperiden. Entacapone tremor, rigidity, sialorrhoea, muscular stiffness and leg is preferred to long-acting preparations of levodopa, whose cramps, but do not generally help with bradykinesia. The adverse are also effective intramuscularly or intravenously in acute effects of entacapone include increased dyskinesias (by drug-induced dystonias. It is an antiviral 365 Section | 4 | Nervous system drug which, given for influenza to a parkinsonian patient, was noticed to be beneficial. It appears to act by increasing synthesis and re- lease of dopamine, and by diminishing neuronal reup- Essential tremor is often, and with justice, called benign, take. Alcohol, is much less effective than levodopa, whose action it through a central action, helps about 50% of patients but enhances slightly, but it has the advantage of reducing is plainly unsuitable for long-term use and a non-selective levodopa-induced dyskinesias. It is more likely to cause tremor, but may cause weakness of the affected part (see confusion in the elderly and so is preferred for younger below). Drug-induced dystonic reactions are seen: • As an acute reaction, often of the torsion type, and Drug-induced parkinsonism occur following administration of dopamine receptor- The classical antipsychotic drugs (see p. Here, there is a genetic failure to elim- parkinsonism and Parkinson’s disease is that the former inate copper absorbed from food so that it accumulates in shows a normal dopamine-transporter binding using a the liver, brain, cornea and kidneys. When drug-induced parkinsonism is trouble- son’s disease, especially with young onset, Huntington’s some, an antimuscarinic drug, e. Movement pansion in the number of available disease-modifying im- of the legs can provide temporary relief; some claim that munomodulatory therapies, all of which are normally it occurs in 5–10% of the general population. Furthermore, in previously healthy pa- for bladder overactivity (injected intravesically), achalasia tients who present with a ‘clinically isolated syndrome’, (injectedendoscopically),analfissure,spasmodicdysphonia, i. Thus the drug may suppress the onset of metalloproteinases that prevent docking of acetylcholine of multiple sclerosis (taken as the point at which more than vesicles at the pre-synaptic membrane, and hence effectively one neurological episode has occurred). Thus inhibition of antigen presentation, T-cell proliferation, dif- the effect of Botox is limited typically to no more than ferentiation and migration into the brain. It is not indicated for patients with purely or antispasticity drugs that typically will have central ner- progressive forms of disease, although it may still be effec- vous system effects such as sedation). The finding of raised antibody levels may unwanted effects (notably opportunistic infections) and prompt change in therapy. Typically administered every 4 weeks, it which it is effective, and its level of efficacy, matches that decreases relapse rate by up to 70%. In certain patients with frequent relapses it at the sphingosine-1-phosphate receptor, causing receptor has beenabletocompletelysuppresstheir futureoccurrence. Thisreceptor isnormallyrequired toallow Thisoccursattheriskofprovokingneworgan-basedautoim- lymphocyte egress from lymph nodes, and so the drug sup- mune diseases, especially thyroid disease (in 40%), immune presses trafficking of autoreactive T cells into the blood. Laquini- (that can cause life-threatening bleeding and renal failure, mod shifts the immunophenotype of T-helper lymphocytes respectively). A small appears to benefit relapses of optic neuritis more than do excess of bone marrow suppression and opportunistic infec- 40 oral steroids but usually requires hospital admission. Multiple other types of polyneuropathy exist, a Constipation is treated with laxatives, while impotence fraction of which will have their specific treatments, e. Oral baclofen or tiza- or doxycycline); diphtheria (antitoxin, penicillin); acute in- nidine, or locally injected botulinum toxin can reduce spas- termittent porphyria (heme arginate and high-carbohydrate ticity, but over-treatment may lead to flaccid weakness. Finally, the role of general supportive The cause of the progressive destruction of upper and lower measures, such as ramps, wheelchairs, stairlifts, prevention motor neurones is unknown. Human tetanus sory, motor or both types of nerve fibre are affected, or di- immunoglobulin 150 units/kg is given intramuscularly vided, depending upon whether it is the myelin sheath that at multiple sites to neutralise unbound toxin.
The main features of trisomy 18 include growth deficiency buy super p-force on line amex erectile dysfunction drugs covered by insurance, characteristic facial appearance trusted 160mg super p-force impotence quiz, clenched hands with overlapping digits buy super p-force 160mg low price erectile dysfunction injection test, rocker bottom feet, cardiac defects, renal abnormalities, exomphalos, myelomeningocele, Figure 5. Ninety percent of moderate developmental delay without congenital malformations or obvious dysmorphic features affected infants die before the age of 6 months but 5% survive beyond the first year of life. About 75% of cases are due to nondisjunction, and are associated with a similar overall risk for recurrent trisomy as in trisomy 18 and 21 cases. The frequency of 13;14 translocations in the general population is around 1 in 1000 and the risk of a trisomic conception for a carrier parent appears to be around 1%. Survivors have very severe mental and physical disability, usually with associated epilepsy, blindness and deafness. Chromosomal mosaicism After fertilisation of a normal egg nondisjunction may occur during a mitotic division in the developing embryo giving rise to daughter cells that are trisomic and nulisomic for the chromosome involved in the disjunction error. The nulisomic cell would not be viable, but further cell division of the trisomic cell, along with those of the normal cells, leads to chromosomal mosaicism in the fetus. Alternatively a chromosome may be lost from a cell in an embryo that was trisomic for that chromosome at conception. Further division of this cell would lead to a population of cells with a normal karyotype, again resulting in mosaicism. In Down syndrome mosaicism, for example, one cell line has a normal constitution of 46 chromosomes and the other has a constitution of 47 21. The severity of mosaic disorders is usually less than non-mosaic cases, but can vary from virtually normal to a phenotype indistinguishable from full trisomy. In subjects with mosaic chromosomal abnormalities the abnormal cell line may not be present in peripheral lymphocytes. In these cases, examination of cultured fibroblasts from a skin biopsy specimen is needed to confirm the diagnosis. Most cases of mosaicism for chromosome 20 detected at amniocentesis, for example, are not associated with fetal abnormality. The trisomic cell line is often confined to extra fetal tissues, with neonatal blood and fibroblast cultures revealing normal karyotypes in infants subsequently delivered at term. In some cases, however, a trisomic cell line is detected in the infant after birth and this may be associated with physical abnormalities or developmental delay. Mosaicism for a marker (small unidentified) chromosome carries a much smaller risk of causing mental retardation if Figure 5. Chromosomal mosaicism detected in chorionic villus samples often reflects an abnormality confined to placental tissue that does not affect the fetus. Further analysis with amniocentesis or fetal blood sampling may be indicated together with detailed ultrasound scanning. This may lead to resulting in Down syndrome spontaneous miscarriage (chromosomes 14, 15, and 22) or liveborn infants with trisomy (chromosomes 13 and 21). Unbalanced Robertsonian translocations may arise spontaneously or be inherited from a parent carrying a balanced translocation. When an apparently balanced recriprocal translocation is detected at amniocentesis it is important to test the parents to see whether one of them carries the same translocation. If the translocation disrupts an autosomal dominant or X linked gene, it may result in a specific disease phenotype. Parent with balanced Abnormalities resulting from an unbalanced reciprocal 7;11 translocation translocation depend on the particular chromosomal fragments Parents that are present in monosomic or trisomic form. Sometimes spontaneous abortion is inevitable; at other times a child with 711 711 multiple abnormalities may be born alive. For other rearrangements, the likely effect can only be assessed from reports of similar cases in the Gametes literature. Prediction is never precise, since reciprocal translocations in unrelated individuals are unlikely to be identical at the molecular level and other factors may influence expression of the chromosomal imbalance. The risk of an unbalanced karyotype occurring in offspring depends on the individual translocation and can also be difficult to determine. Offspring The risk of a liveborn affected child is less for families ascertained through a history of recurrent pregnancy loss Normal Balanced Trisomy 7q Monosomy 7q where there have been no liveborn affected infants. The best known of these are cri du chat syndrome caused by a terminal deletion of the short arm of chromosome 5 (5p-) and Wolf–Hirschhorn syndrome caused by a terminal deletion of the short arm of chromosome 4 (4p-). Microdeletions Several genetic syndromes have now been identified by molecular cytogenetic techniques as being due to chromosomal deletions too small to be seen by conventional analysis. The term contiguous gene syndrome is applied when several genes are affected, and in these disorders the features present may be determined by the extent of the deletion. The chromosomal location of a microdeletion may be initially identified by the presence of a larger visible cytogenetic deletion in a proportion of cases, as in Prader–Willi and Angelman syndrome, or by finding a chromosomal translocation in an affected individual, as occured in William syndrome. A microdeletion on chromosome 22q11 has been found in most cases of DiGeorge syndrome and velocardiofacial syndrome, and is also associated with certain types of isolated congenital heart disease. With an incidence of 8 per 1000 live births, congenital heart disease is one of the most common birth defects. The aetiology is usually unknown and it is therefore important to identify cases caused by 22q11 deletion. Isolated cardiac defects due to microdeletions of chromosome 22q11 often include outflow tract abnormalities. Hospital, Manchester) 22 Common chromosomal disorders DiGeorge syndrome involves thymic aplasia, parathyroid Box 5. Velocardiofacial syndrome was described as Syndrome Chromosomal deletion a separate clinical entity, but does share many features in DiGeorge 22q11 common with DiGeorge syndrome. The features include mild Velocardiofacial 22q11 Prader–Willi 15q11-13 mental retardation, short stature, cleft palate or speech defect Angelman 15q11-13 from palatal dysfunction, prominent nose and congenital William 7q11 cardiac defects including ventricular septal defect, right sided Miller–Dieker (lissencephaly) 17p13 aortic arch and tetralogy of Fallot. Sex chromosome abnormalites are often detected coincidentally at amniocentesis or during investigation for infertility. When more than one additional sex chromosome is present learning disability or physical abnormality is more likely. Turner syndrome Turner syndrome is caused by the loss of one X chromosome (usually paternal) in fetal cells, producing a female conceptus with 45 chromosomes. Mary’s Hospital, Manchester) ultrasonography, which shows cystic hygroma, chylothorax, asictes and hydrops. The most consistent features of the syndrome are short stature and infertility from streak gonads, but neck webbing, broad chest, cubitus valgus, coarctation of the aorta, renal anomalies and visual problems may also occur. Intelligence is usually within the normal range, but a few girls have educational or behavioural problems. Associations with autoimmune thyroiditis, hypertension, obesity and non-insulin dependent diabetes have been reported. Other X chromosomal abnormalities including deletions or rearrangements can also result in Turner syndrome. Triple X syndrome The triple X syndrome occurs with an incidence of 1 in 1200 liveborn female infants and is often a coincidental finding. Educational problems are encountered more often in this group than in the other types of sex chromosome abnormalities.
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