By C. Esiel. Southern Nazarene University. 2018.
Chorionic villus sampling (CVS)—A procedure Prenatal testing—Testing for a disease such as a used for prenatal diagnosis at 10-12 weeks gesta- genetic condition in an unborn baby cheap ponstel 500 mg on line muscle relaxant metaxalone side effects. These cells are then tested for tion of body structures and controlling the basic chromosome abnormalities or other genetic dis- functions of the human body order 500mg ponstel overnight delivery muscle relaxant football commercial. White matter—A substance found in the brain and Chromosome—A microscopic thread-like structure nervous system that protects nerves and allows found within each cell of the body and consists of a messages to be sent to and from the brain to the var- complex of proteins and DNA. Carrier testing for the three the other ASPA gene change is common in those of other common ASPA gene mutations identifies approximately ethnic backgrounds. Testing for other types of changes in 97–99% of Ashkenazi Jewish carriers and 40–55% of the ASPA gene is only done on a research basis. Carrier testing of individuals without a family history Carrier testing of Canavan disease is only recommended for people of DNA testing is the only means of identifying carri- Ashkenazi Jewish background since they have a higher risk ers of Canavan disease. As of 1998, both the American College of be first performed on the affected family member. If a Obstetricians and Gynecologists and the American College change in the ASPA gene is detected, then carrier testing of Medical Genetics recommend that DNA testing for can be performed in relatives such as siblings, with an Canavan disease be offered to all Ashkenazi Jewish cou- accuracy of greater than 99%. If the affected relative does ples who are planning children or who are currently preg- not possess a detectable ASPA gene change, then carrier nant. If only one member of the couple is of Ashkenazi testing will be inaccurate and should not be performed. If Jewish background than testing of the Jewish partner DNA testing of the affected relative cannot be performed, should be performed first. If the Jewish partner is a carrier, carrier testing of family members can still be performed than testing of the non-Jewish partner is recommended. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 187 Prenatal Testing Resources Prenatal testing through chorionic villus sampling BOOKS (CVS) and amniocentesis is available to parents who are Scriver, C. PERIODICALS Some parents are known to be carriers for Canavan dis- ACOG committee opinion. Matalon, Reuben, Kimberlee Michals-Matalon, and Rajinder Seizures and irritability can often be controlled through Kaul. Feeding tubes are either inserted ORGANIZATIONS through the nose (nasogastric tube) or through a perma- Canavan Foundation. Fairwood Professional Build- benefit from special education programs and physical ing, New Fairwood, CT 06812. Most people with Canavan disease live into their teens Matalon, Reuben and Kimberlee Michals-Matalon. It is, therefore, impossible to predict the lifespan of a particular individual with Canavan disease. Lisa Maria Andres, MS, CGC 188 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Canavan-VanBogaert-Bertrand disease see mutation in the DNA are called carcinogens. For example, certain hor- Canavan disease mones have been shown to have an effect on the growth or control of a particular cell line. Hormones are sub- stances made by one organ and passed through the blood- stream to affect the function of other cells in another organ. ICancer While there is scientific evidence that both environ- Definition mental and genetic factors play a role in most cancers, Cancer is not just one disease, but a large group of only 5-10% of all cancers are classified as hereditary. This results in a greater risk these cells to spread to distant sites (metastasis). However, if someone has a cancer-related gene, it does not mean they will automatically get cancer. Rather, this person is thought to be “predisposed” to a type of cancer, Description or more likely to get this cancer when compared to the Cancer, by definition, is a disease of the genes. Various cancers are known to have a Genes are formed from deoxyribonucleic acid (DNA) hereditary component in some cases. They carry the hereditary breast cancer, colon cancer, ovarian cancer, skin can- instructions for the cell to make the proteins required for cer and prostate cancer. Proteins are special chemical com- Aside from genes, certain physiological traits that pounds that mostly contain carbon, hydrogen, oxygen, are inherited can contribute to cancers as well. They are required by our bodies to carry out ple, fair skin makes a person more likely to develop skin all the processes that allow us to breathe, think, move, cancer, but only if they also have prolonged exposure to etc. Many the most common types include: genes produce proteins that are involved in controlling the processes of cell growth and division.
The gastrointestinal adnexae 93 tine in such a case is left as a narrow pedicle discount ponstel 500mg with visa spasms of the colon, which allows volvulus of the whole small intestine to occur (volvulus neonatorum) buy generic ponstel 500 mg online spasms under left breastbone. The gastrointestinal adnexae: liver, gall-bladder and its ducts, pancreas and spleen The liver (Fig. It is related by its domed upper surface to the diaphragm, which separates it from pleura, lungs, pericardium and heart. Its postero-inferior (or visceral) surface abuts against the abdominal oesophagus, the stomach, duodenum; hepatic ﬂexure of colon and the right kidney and suprarenal, as well as carrying the gall-bladder. The liver is divided into a larger right and small left lobe, separated superiorly by the falciform ligament and postero-inferiorly by an H-shaped arrangement of fossae (Fig. Two subsidiary lobes are marked out on the visceral aspect of the liver between the limbs of this H— the quadrate lobe in front and the caudate lobe behind. The ligamentum teres is the obliterated remains of the left umbilical vein which, in utero, brings blood from the placenta back into the fetus. The liga- mentus venosum is the ﬁbrous remnant of the fetal ductus venosus which shunts oxygenated blood from this left umbilical vein to the inferior vena cava, short-circuiting the liver. It is easy enough to realize, then, that the grooves for the ligamentum teres, ligamentum venosum and inferior vena cava, representing as they do the pathway of a fetal venous trunk, are con- tinuous in the adult. Lying in the porta hepatis (which is 2in (5cm) long) are: 1the common hepatic duct—anteriorly; 2the hepatic artery—in the middle; 3the portal vein—posteriorly. As well as these, autonomic nerve ﬁbres (sympathetic from the coeliac 94 The abdomen and pelvis Coronary ligament Left triangular ligament Left lobe Falciform ligament Round ligament (ligamentum teres) Gall-bladder Right lobe (a) Gall-bladder Porta hepatis Quadrate lobe Right lobe Hepatic artery Hepatic portal vein Fissure for ligamentum teres Common Left lobe hepatic Caudate lobe duct Fissure for ligamentum venosum Left hepatic vein (b) Inferior vena cava Groove + GB lig. The gastrointestinal adnexae 95 axis and parasympathetic from the vagus), lymphatic vessels and lymph nodes are found there. Peritoneal attachments The liver is enclosed in peritoneum except for a small posterior bare area, demarcated by the peritoneum from the diaphragm reﬂected on to it as the upper and lower layers of the coronary ligament. The falciform ligament ascends to the liver from the umbilicus, somewhat to the right of the midline, and bears the ligamentum teres in its free border. The ligamentum teres passes into its ﬁssure in the inferior surface of the liver while the falciform ligament passes over the dome of the liver and then divaricates. Its right limb joins the upper layer of the coronary liga- ment and its left limb stretches out as the long narrow left triangular ligament which, when traced posteriorly and to the right, joins the lesser omentum in the upper end of the ﬁssure for the ligamentum venosum. The lesser omentum arises from the ﬁssures of the porta hepatis and the ligamentum venosum and passes as a sheet to be attached along the lesser curvature of the stomach. Structure The liver is made up of lobules, each with a solitary central vein which is a tributary of the hepatic vein which, in turn, drains into the inferior vena cava. In spaces between the lobules, termed portal canals, lie branches of the hepatic artery (bringing systemic blood) and the portal vein, both of which drain into the central vein by means of sinusoids traversing the lobule. Branches of the hepatic duct also lie in the portal canals and receive ﬁne bile capillaries from the liver lobules. Segmental anatomy The gross anatomical division of the liver into a right and left lobe, demar- cated by a line passing from the attachment of the falciform ligament on the anterior surface to the ﬁssures for the ligamentum teres and ligamentum venosum on its posterior surface, is simply a gross anatomical descriptive term with no morphological signiﬁcance. Studies of the distribution of the hepatic blood vessels and ducts have indicated that the true morphological and physiological division of the liver is into right and left lobes demar- cated by a plane which passes through the fossa of the gall-bladder and the fossa of the inferior vena cava. Although these two lobes are not differenti- ated by any visible line on the dome of the liver, each has its own arterial and portal venous blood supply and separate biliary drainage. This mor- phological division lies to the right of the gross anatomical plane and in this the quadrate lobe comes to be part of the left morphological lobe of the liver while the caudate lobe divides partly to the left and partly to the right lobe (Fig. Note that the quadrate lobe is morphologically a part of the left lobe while the caudate lobe belongs to both right and left lobes. The right and left morphological lobes of the liver can be further subdi- vided into a number of segments, four for each lobe (Fig. The student need not learn the details of these, but of course to the hepatic surgeon, car- rying out a partial resection of the liver, knowledge of these segments, with their individual blood supply and biliary drainage, is of great importance. At the hilum of the liver, the hepatic artery, portal vein and bile duct each divide into right and left branches and there is little or no anastomosis between the divisions on the two sides (Fig.
It generally affects the elderly scribed as jerky resistance that has been likened to the and is estimated to afﬂict more than 1% of individuals movement of a cogwheel (cogwheel rigidity) buy 500mg ponstel free shipping spasms around heart, is also an over the age of 65 order ponstel 250mg with amex spasms hiccups. Bradykinesia, an ial forms of parkinsonism with an autosomal dominant extreme slowness of movement, is the most disabling pattern of inheritance. These genes encode kinesia results in a typical stooped posture when the for -synuclein, a protein found in abundance in vesi- person is standing or walking and a characteristic cles and synaptic regions, and for parkin and ubiquitin shufﬂing gait marked by the absence of normal arm- carboxy-terminal hydroxylase, both of which are in- swinging movements. Inability to swallow leads to drooling, while bradyki- speciﬁc entities, such as viral inﬂammation (e. Orthostatic hypotension may also be ob- trauma, stroke, and poisoning by manganese, carbon served and may complicate therapy. Cognitive dysfunc- monoxide, pesticide, or 1-methyl-4-phenyl,-1,2,3,6-tetra- tion and dementia are also seen in a small percentage of hydropyridine (MPTP). Relatively smooth In postmortem examination of tissue, the substantia functioning of motor control is maintained until neu- nigra is readily identiﬁable because of the dark pigmen- ronal loss is such that it causes an 80% reduction of tation in the neurons that is the result of the accumula- dopamine in the striatum. At this time, clinical symptoms tion of neuromelanin, a substance whose neurochemical appear and then worsen with increasing neuronal loss. Lewy bodies are com- is, iatrogenic parkinsonism, which often is a complica- posed of many cytoskeleton and other proteins, includ- tion of antipsychotic therapy, especially following the ing -synuclein, ubiquitin, and synaptophysin. It is not use of the butyrophenone and phenothiazine drug clear whether the formation of these inclusions con- classes (see Chapter 34). Unlike idiopathic parkinson- tributes to neuronal degeneration or they are merely a ism, striatal content of dopamine is not reduced by ad- byproduct of degenerating neurons. In contrast, they produce a functional decrease in dopamine activity by blocking Basal Ganglia Anatomy the action of dopamine on postsynaptic dopamine re- ceptors. They are composed of several brain re- gions, including the neostriatum and the substantia ni- Clinical Findings gra (Fig. The are tremor, rigidity, and bradykinesia, although the time dopamine neurons originate in the substantia nigra pars of onset and the relative severity of each symptom may compacta and project to the neostriatum, where they differ in individual patients. Tremors are often unilat- synapse on the input glutamatergic terminals and on eral in onset, present at rest, and cease during voluntary striatal projection neurons that use the neurotransmit- movement. Several brain regions and numerous neurotransmitters are involved with the function and regulation of neuronal activity within the basal ganglia. The direct pathway (2) the striatum to SNpr) becomes less active, whereas the indirect pathway (3) striatum to globus pallidus to STN to SNpr) increases in activity. The consequence is an enhanced activation of SNpr outﬂow neurons (4), which exert an overall reduction of the thalamic–cortical pathway (5). DA, dopamine; Glu, glutamate, excitatory transmitter; GABA, - amino butyric acid, inhibitory transmitter; ACh, acetylcholine, excitatory intrastriatal transmitter. GP, globus pallidus; SNpc, substantia nigra pars compacta; SNpr, substantia nigra, pars reticulate; STN, subthalamic nucleus. Dopamine is a catecholamine (see Chapter 10 and The inability of the neurons to eliminate the oxidative Fig. Dopamine actions on D3 4 1 receptors ex- source of oxidative stress may be dopamine metabolism ert an excitatory effect, whereas the actions of (Fig. The stantia nigra created by the loss of dopamine actions loss of striatal dopamine produces an imbalance in in- within the striatum could lead to excitotoxicity that is formation processing in the neostriatum that modiﬁes mediated by glutamate. Also impor- tant in neural transmission are the striatal interneurons Therapy of Parkinsonism that are found within the conﬁnes of the striatum, that use the excitatory neurotransmitter acetylcholine, and Since there is no cure for parkinsonism, the aim of phar- that modulate the activity of striatal output neurons. This is obtained through the use of drugs that either in- crease dopaminergic actions or diminish neuronal out- Possible Mechanisms ﬂow from the striatum. These drugs include levodopa, of Neurodegeneration which increases brain dopamine levels; dopamine ago- The mechanisms responsible for the degeneration of nists, which directly stimulate dopamine receptors; dopamine neurons are not known, but hypotheses in- monoamine oxidase (MAO) inhibitors, which prevent clude effects such as oxidative stress and excitotoxicity. Dopamine itself does not cross the Levodopa and Carbidopa blood-brain barrier and therefore has no CNS effects. Levodopa (L-DOPA), the most reliable and effective However, levodopa, as an amino acid, is transported drug used in the treatment of parkinsonism, can be con- into the brain by amino acid transport systems, where it SYNTHESIS COOH CH2 CH NH2 HO Tyrosine Tyrosine Hydroxylase COOH HO CH2 CH NH2 HO DOPA Aromatic Amino Acid Decarboxylase HO CH2 CH2 NH2 HO DA METABOLISM 2 H2O Catechol-O-methyl Monoamine H2O2 2 Oxidase Fe Transferase • OH OH Fe 3 CH3O CH2 CH2 NH2 HO CH2COOH HO HO MTA DOPAC Monoamine Catechol-O-methyl Oxidase Transferase CH3O CH2COOH HO HVA FIGURE 31. The metabolism of dopamine produces hydrogen peroxide, which can be converted to water by glutathione peroxidase (GPX) or can in the presence of iron produce reactive hydroxyl radicals.
From a practical perspective there have been many placebo-controlled trials of memory-enhancing agents in older subjects 250mg ponstel mastercard spasms left upper quadrant. This shortterm improvement is perhaps related to learning effect ponstel 500mg without a prescription spasms poster, but some of the outcome measures are not sensitive to learning effects and the learning effect would be expected to carry over into succeeding test sessions. Thus, the short-term improvements may be related to placebo or expectancy effects. Although this may also be related to placebo effect, there are other explanations as well, including subject selection and Hawthorne effects related to attention and cognitive stimulation associated with participating in the study. Complementary therapies in neurology 268 CONCLUSIONS There are factors related to a clinical interaction that may produce improvement in patient outcomes without directly affecting the underlying pathophysiology of a disease. Methodological artifacts such as regression to the mean and natural history have contributed to confusion about these factors. However, there are clearly effects on outcomes that are dependent on expectations of patients, whether these expectations are related to culture, previous interactions with the clinical setting, or conditioning. The biological basis of these effects are starting to be understood, especially in the realm of analgesic responses, but also in the realms of psychoneuroimmunology and neuroendocrinology. It will be helpful to understand the placebo effect from a biological basis in order to try to maximize health. Additionally, improving clinical trial design and interpretation will require a better understanding and characterization of non-specific healing responses comprising the placebo effect. The role of expectancies in the placebo effect and their use in the delivery of health care: a systematic review. Am J Public Health 2002; 92:1564–6 Placebo effect: clinical perspectives and potential mechanisms 269 14. Depressed affect, hopelessness, and the risk of ischemic heart disease in a cohort of U. Optimists vs pessimists: survival rate among medical patients over a 30-year period. Optimism-pessimism assessed in the 1960s and self-reported health status 30 years later. Explanatory mechanisms for placebo effects: cultural influences and the meaning response. Three perspectives on the placebo response: expectancy, conditioning, and meaning. The power of nonspecific effects in healing: implications for psychosocial and biological treatments. A videotaped CIBIC for dementia patients: validity and reliability in a simulated clinical trial. Placebo effect and placebo concept: a critical methodological and conceptual analysis of reports on the magnitude of the placebo effect. An investigation of drug expectancy as a function of capsule color and size and preparation form. Placebo effect in the acute treatment of migraine: subcutaneous placebos are better than oral placebo. Comparison of internal mammary artery ligation and sham operation for angina pectoris. Psychosom Med 1969; 31:227–46 Placebo effect: clinical perspectives and potential mechanisms 271 66. A longitudinal study of the development of anticipatory nausea and vomiting in cancer chemotherapy patients: the role of absorption and autonomic perception. Influence of adherence to treatment and response of cholesterol on mortality in the coronary drug project. Oral antibiotic prophylaxis in patients with cancer: a double-blind randomized placebocontrolled trizl. A study of the variations in the response regarding duodenal ulcer when treated with placebo by different investigators. Can physicians warn patients of potential side effects without fear of causing those side effects?