By Q. Tempeck. Pratt Institute.
Keratoacanthomas are skin-colored or reddish buy discount propecia 5mg online, Diagnosis firm skin nodules that are distinct from sebaceous neo- Since not all families with the features of Muir-Torre plasms upon microscopic examination cheap propecia 5mg with amex. The skin findings syndrome have identifiable mismatch repair gene alter- in Muir-Torre syndrome can either appear before order propecia 5 mg without prescription, during buy propecia 1mg without a prescription, ations propecia 1mg without prescription, diagnosis is based mainly on the presence of the or after the development of the internal cancer. Muir-Torre syndrome is defined by the presence of certain types of sebaceous Internal findings neoplasms (sebaceous adenomas, sebaceous epithe- Internal organ cancers are common in Muir-Torre liomas, sebaceous carcinomas and keratoacanthomas syndrome. Several individuals with Muir-Torre syn- with sebaceous differentiation) and at least one internal GALE ENCYCLOPEDIA OF GENETIC DISORDERS 759 organ cancer in the same individual. Muir-Torre syn- ORGANIZATIONS drome may also be diagnosed if an individual has multi- American Cancer Society. Screening recommendations have been proposed for Kristin Baker Niendorf, MS, CGC individuals with Muir-Torre or at-risk relatives. In addi- tion to regular screening for the skin findings, screening for internal cancers may be considered. The effectiveness of screening for individuals with or at risk for Muir-Torre syndrome has yet to be proven. IMultifactorial inheritance Definition Treatment and management Many common congenital malformations and dis- While it is not possible to cure the genetic abnor- eases are caused by a combination of genetic and envi- mality that results in Muir-Torre syndrome, it is possible ronmental factors. The term multifactorial inheritance is to prevent and treat the symptoms of the syndrome. The used to describe conditions that occur due to these multi- skin tumors are removed by freezing or cutting. In contrast to dominantly or recessively nodes, small bean-sized lumps of tissue that are part of inherited diseases, multifactorial traits do not follow any the immune system, are involved, these must be removed particular pattern of inheritance in families. Radiation, high energy rays, to the affected area can Multifactorial conditions do tend to cluster in families, be beneficial. A medication, isotretinoin, may reduce the but pedigree analysis does not reveal a specific pattern risk of skin tumors. Some multifactorial conditions the standard manner, removal by surgery and possible occur because of the interplay of many genetic factors treatment with radiation or cancer-killing medication and limited environmental factors. Others occur because of limited genetic factors and significant environmental (chemotherapy). The number of genetic and environmental factors before colon cancer develops is an option with HNPCC vary, as does the amount of impact of each factor on the and may be considered for individuals with Muir-Torre presence or severity of disease. Prognosis Examples of congenital malformations following a The cancers associated wth Muir-Torre syndrome multifactorial pattern of inheritance include cleft lip and are usually diagnosed at earlier ages than typically seen. Adult onset For instance, the average age at diagnosis of colorectal diseases that follow multifactorial inheritance include cancer is 10 years earlier than in the general population. For instance, height, intelligence, and blood pressure are all may be better for a person with colon cancer due to Muir- determined in part by genetic factors, but are influenced Torre syndrome than colon cancer in the general popula- by environmental factors. Resources Continuous and discontinuous traits BOOKS Some multifactorial traits are considered continuous Flanders, Tamar et al. In because there is bell shaped distribution of those traits in Inherited Susceptibility: Clinical, predictive and ethical the population. Other traits are discontinuous because there is a Hodgson, Cambridge University Press, 1998. An exam- ple would be a malformation like a cleft lip, in which the KEY TERMS person is either affected or unaffected. In both cases, the genetic and environmental factors that are involved in the Candidate gene—A gene that encodes proteins occurrence of the condition are referred to as liability. Pyloric stenosis Genetic heterogeneity—The occurrence of the An example of a discontinuous multifactorial trait same or similar disease, caused by different genes that follows the threshold model is pyloric stenosis. Pyloric stenosis is a narrowing of the pylorus, the con- Loci—The physical location of a gene on a chro- nection between the stomach and the intestine. Symptoms of pyloric stenosis include vomiting, consti- Phenotype—The physical expression of an indi- pation, and weight loss. The condition is five Polymorphism—A change in the base pair times more common in males. The liability is higher in sequence of DNA that may or may not be associ- women, such that more or stronger genetic and environ- ated with a disease. Therefore, male first-degree relatives of a female who is affected with pyloric stenosis have a higher risk to be born with the condition than do female first-degree • Recurrence risks quoted are averages and the true risk relatives of the same person. For instance, North Carolina, South Carolina, and Texas all have a higher incidence of neural tube defects that other states in the United States. Ireland has Recurrence risks a higher incidence of neural tube defects than many other Recurrence risks for multifactorial traits are based countries.
Errors brought to the Andrea Lopeman buy propecia 5mg fast delivery, Programmer/Analyst attention of the publisher and verified to the satisfaction of the publisher will be corrected in future editions quality propecia 1 mg. Barbara Yarrow 5 mg propecia mastercard, Manager cheap 1 mg propecia free shipping, Imaging and Multimedia This book is printed on recycled paper that meets Environmental Content Protection Agency standards propecia 1mg low cost. Robyn Young, Project Manager, Imaging and The paper used in this publication meets the minimum requirements of Multimedia Content American National Standard for Information Sciences-Permanence Randy Bassett, Imaging Supervisor Paper for Printed Library Materials, ANSI Z39. Robert Duncan, Senior Imaging Specialist This publication is a creative work fully protected by all applicable Pamela A. Reed, Coordinator, Imaging and Multimedia copyright laws, as well as by misappropriation, trade secret, unfair com- petition, and other applicable laws. The authors and editors of this work Content have added value to the underlying factual material herein through one or more of the following: unique and original selection, coordination, Maria Franklin, Permissions Manager expression, arrangement, and classification of the information. Ryan Thomason, Permissions Associate Gale Group and design is a trademark used herein under license. Lori Hines, Permissions Assistant All rights to this publication will be vigorously defended. Kenn Zorn, Product Manager Copyright © 2002 Michelle DiMercurio, Senior Art Director Gale Group 27500 Drake Road Mary Beth Trimper, Manager, Composition and Farmington Hills, MI 48331-3535 Electronic Prepress All rights reserved including the right of reproduction in whole or in Evi Seoud, Assistant Manager, Composition Purchasing part in any form. Montgomery, Manager, Data Capture Printed in the United States of America Gwendolyn S. Tucker, Project Administrator Beverly Jendrowski, Data Capture Specialist Indexing provided by: Synapse. Illustrations created by: Library of Congress Cataloging-in-Publication Data Argosy, West Newton, Massachusetts The Gale encyclopedia of genetic disorders / Stacey L. The rod cells are located prima- disease rily outside of the macula and they allow for peripheral (side) and night vision. Most of the photoreceptor cells inside of the macula, however, are the cone cells, which are responsible for perceiving color and for viewing objects directly in front of the eye (central vision). If the IMacular degeneration— macula is diseased, as in AMD, color vision and central age-related vision are altered. Definition Macular degeneration age-related (AMD) is one of Dry AMD the most common causes of vision loss among adults Approximately 90% of individuals with AMD have over age 55 living in developed countries. This condition is sometimes referred to as the breakdown of the macula, a small spot located in the nonexudative, atrophic, or drusenoid macular degenera- back of the eye. In this form of AMD, some of the layers of retinal directly in front of them (called central vision), as well as cells (called retinal pigment epithelium, or RPE cells) fine visual details. When the RPE cells are no longer able to provide this “clean-up” function, fatty Description deposits called drusen begin to accumulate, enlarge and increase in number underneath the macula. The drusen In order to understand how the macula normally formation can disrupt the cones and rods in the macula, functions and how it is affected by AMD, it is important causing them to degenerate or die (atrophy). The eye is made leads to central and color vision problems for people with up of many different types of cells and tissues that all dry AMD. However, some people with drusen deposits work together to send images from the environment to have minimal or no vision loss, and although they may the brain, similar to the way a camera records images. Dry AMD is some- lands on the retina, which is a very thin tissue that lines times called “nonexudative”, because even though fatty the inside of the eye. The retina is actually made up of 10 drusen deposits form in the eye, people do not have leak- different layers of specialized cells, which allow the age of blood or other fluid (often called exudate) in the retina to function similarly to film in a camera, by record- eye. In addition, approximately 10% of people area located at the back of the eye, in the central part of with dry AMD eventually develop wet AMD. The retina contains many specialized cells called photoreceptors that sense light coming into the eye Wet AMD and convert it into electrical messages that are then sent to the brain through the optic nerve. This form of AMD is also called subretinal neovascular- GALE ENCYCLOPEDIA OF GENETIC DISORDERS 691 ization, choroidal neovascularization, exudative form or KEY TERMS disciform degeneration. Wet AMD is caused by leakage of fluid and the formation of abnormal blood vessels Central vision—The ability to see objects located (called “neovascularization”) in a thin tissue layer of the directly in front of the eye. The choroid is located underneath sary for reading and other activities that require the retina and the macula, and it normally supplies them people to focus on objects directly in front of with nutrients and oxygen.
A prerequisite for rapid renal elimination is a hepatic conjugation re- action (p buy generic propecia 1 mg on line. At high dosage buy generic propecia 1mg on line, the conjugation may be- Lüllmann propecia 1 mg amex, Color Atlas of Pharmacology © 2000 Thieme All rights reserved cheap propecia 5mg without prescription. Antipyretic Analgesics 201 High dose t1/2 =13-30h 50% Salicylic acid Low dose t1/2~3h t1/2 =1-2h 90% Acetyl- t1/2 =15min salicylic 99% acid 95% 99% Diclofenac Ibuprofen Azapropazone t1/2 ~2h t1/2 =9-12h Piroxicam Naproxen t1/2~50h 99% 99% t1/2~14h Plasma protein binding A order propecia 5 mg without a prescription. Nonsteroidal antiinflammatory drugs (NSAIDs) Arachidonic acid Leukotrienes NSAID-induced nephrotoxicity Renal blood Prostaglandins Airway resistance flow NSAID-induced Mucus production NSAID-induced gastropathy Acid secretion asthma Mucosal blood flow B. NSAIDs: group-specific adverse effects Lüllmann, Color Atlas of Pharmacology © 2000 Thieme All rights reserved. In the resting at its physiological level, excess heat state, the metabolic activity of vital or- must be dissipated—the patients have a gans contributes 60% (liver 25%, brain hot skin and are sweating. The absolute contribution controller (B1) can be inactivated by to heat production from these organs neuroleptics (p. This can be exploited in the treat- body temperature is programmed in the ment of severe febrile states (hyperpy- hypothalamic thermoregulatory center. Cutaneous blood flow can perature (freezing to death in drunken- range from ~ 0 to 30% of cardiac output, ness). The body Heat dissipation can also be responds by restricting heat loss (cuta- achieved by increased production of neous vasoconstriction! The sympathetic system can either re- duce heat loss via vasoconstriction or promote it by enhancing sweat produc- tion. If insufficient heat is dissipated through this route, overheating occurs (hyperthermia). Thyroid hyperfunction poses a particular challenge to the thermoregu- Lüllmann, Color Atlas of Pharmacology © 2000 Thieme All rights reserved. Antipyretic Analgesics 203 Thermoregulatory Sympathetic system center "-Adreno- Acetylcholine (set point) ceptors receptors Hyper- thyroidism 37º Cutaneous Sweat Increased blood flow production heat production Respiration Heat production Parasym- patholytics (Atropine) Heat Heat Inhibition production loss of sweat production Metabolic activity Hyperthermia 37º Body temperature A. Thermoregulation Neuroleptics Ethanol Pyrogen Antipyretics Barbiturates Preferential Heat e. Disturbances of thermoregulation Lüllmann, Color Atlas of Pharmacology © 2000 Thieme All rights reserved. In sensory nerves, such an effect zures (countermeasure: injection of a is desired when painful procedures benzodiazepine, p. Nerve im- ¼ blockade of cardiac impulse conduc- pulse conduction occurs in the form of tion, as evidenced by impaired AV an action potential, a sudden reversal in conduction or cardiac arrest (coun- resting transmembrane potential last- termeasure: injection of epineph- ing less than 1 ms. Depression of excitatory pro- tial is triggered by an appropriate stim- cesses in the heart, while undesired ulus and involves a rapid influx of Na+ during local anesthesia, can be put to into the interior of the nerve axon (A). Local upon being opened (activated), permits anesthetics are applied via different rapid movement of Na+ down a chemi- routes, including infiltration of the tis- cal gradient ([Na+]ext ~ 150 mM, [Na+]int sue (infiltration anesthesia) or injec- ~ 7 mM). Local anesthetics are capable tion next to the nerve branch carrying of inhibiting this rapid inward flux of fibers from the region to be anesthe- Na+; initiation and propagation of exci- tized (conduction anesthesia of the tation are therefore blocked (A). In each case, the local an- vors incorporation into membrane esthetic drug is required to diffuse to interphases, boundary regions between the nerves concerned from a depot polar and apolar domains. Im- dence suggests that Na+-channel block- pulse conduction in sensory nerves is ade results from binding of local anes- inhibited at a concentration lower than thetics to the channel protein. This differ- certain that the site of action is reached ence may be due to the higher impulse from the cytosol, implying that the drug frequency and longer action potential must first penetrate the cell membrane duration in nociceptive, as opposed to (p. Local anesthetic activity is also Alternatively, it may be related to shown by uncharged substances, sug- the thickness of sensory and motor gesting a binding site in apolar regions nerves, as well as to the distance of the channel protein or the surround- between nodes of Ranvier. Since local anesthetics block Na+ polarization can still occur after block- influx not only in sensory nerves but al- ade of three or four nodal rings, the area so in other excitable tissues, they are exposed to a drug concentration suffi- applied locally and measures are taken cient to cause blockade must be larger (p. Too rapid entry into the This relationship explains why sen- sory stimuli that are conducted via Lüllmann, Color Atlas of Pharmacology © 2000 Thieme All rights reserved. Local Anesthetics 205 Local anesthetic Propagated Na+ impulse Activated Na+-entry + Na -channel Peripheral nerve Na+ CNS Blocked Na+-channel Conduction Restlessness, block convulsions, Na+ respiratory Blocked paralysis Na+-channel Heart polar Cationic Uncharged Impulse amphiphilic local Local conduction + local anesthetic application cardiac arrest apolar anesthetic A. Inhibition of impulse conduction in different types of nerve fibers Lüllmann, Color Atlas of Pharmacology © 2000 Thieme All rights reserved.