By Y. Stejnar. Wilkes University.
CP that has a postnatal cause is during pregnancy and a risk for CP are difficult to prove penegra 50mg on line. Furthermore generic penegra 100mg visa, any substance that increases the mother and child (mother Rh negative, baby Rh positive) risk for premature delivery and low birth weight, such as can result in severe anemia in the baby (erythroblastosis alcohol, tobacco, or cocaine, among others, might indi- fetalis). Rh disease in the The fetus receives all nutrients and oxygen from newborn is now rare in developed countries due to routine blood that circulates through the placenta. Therefore, screening of maternal blood type and treatment of preg- anything that interferes with normal placental function nancies at risk. The routine, effective treatment of jaundice might adversely affect development of the fetus, includ- due to other causes has also made it an infrequent cause of ing the brain, or might increase the risk for premature CP in developed countries. Structural abnormalities of the placenta, prema- recurrence of Rh disease if treatment is not provided. A seizure disorder Certain conditions in the mother during pregnancy early in life may cause CP, or may be the product of a might pose a risk to fetal development leading to CP. Women with autoimmune anti-thyroid or anti-phospho- Unexplained (idiopathic) seizures are hereditary in only a lipid (APA) antibodies are at slightly increased risk for small percentage of cases. A potentially important clue uncov- healthy at or near term, intracerebral hemorrhage and ered recently points toward high levels of cytokines in the brain embolism, like fetal stroke, are sometimes genetic. Physical trauma to an infant or child resulting in Cytokines are proteins associated with inflammation, brain injury, such as from abuse, accidents, or near such as from infection or autoimmune disorders, and they drowning/suffocation, might cause CP. More research tion of a toxic substance such as lead, mercury, poisons, is needed to determine the exact relationship, if any, or certain chemicals could cause neurological damage. A Accidental overdose of certain medications might also woman has some risk of developing the same complica- cause similar damage to the central nervous system. Prematurity and multiple birth pregnancy Serious physical trauma to the mother during preg- Advances in the medical care of premature infants in nancy could result in direct trauma to the fetus as well, or the last 20 years have dramatically increased the rate of 214 GALE ENCYCLOPEDIA OF GENETIC DISORDERS survival of these fragile newborns. However, as gesta- tional age at delivery and birth weight of a baby decrease, KEY TERMS the risk for CP dramatically increases. In the case of cerebral a preterm infant (32–37 weeks) is increased about five- palsy, lack of oxygen to the brain. Survivors of Ataxia—A deficiency of muscular coordination, extremely preterm births (less than 28 weeks) face as especially when voluntary movements are much as a fifty-fold increase in risk. Two factors are involved in the risk for CP associ- Cerebral palsy—Movement disability resulting ated with prematurity. The tendency toward Cytokine—A protein associated with inflammation premature delivery tends to run in families, but the that, at high levels, may be toxic to nerve cells in genetic mechanisms are far from clear. An increase in multiple birth pregnancies in recent Diplegia—Paralysis affecting like parts on both years, especially in the United States, is blamed on the sides of the body, such as both arms or both legs. As the number of fetuses Dorsal rhizotomy—A surgical procedure that cuts in a pregnancy increases, the risks for abnormal develop- nerve roots to reduce spasticity in affected mus- ment and premature delivery also increase.
However purchase penegra 50mg with visa, because cells are noisy purchase penegra 50mg without prescription, our estimate would have a large variance from trial to trial, even though the actual direction of movement did not change. In fact, if the tuning curves were exactly cosine functions, the estimate would be optimal in the sense that its variance would be as small as possible. Where this condition has been approximately met, experiments have generally demonstrated that a population code could success- fully be used to estimate the input variable from noisy neuronal discharge. In general, a population code could also be used to map an input variable x into any other variable y. Basis functions are a set of functions such that when they are linearly combined, they can approximate almost any linear or nonlinear function. For example, Pouget and Sejnowski27 suggested that neurons in the parietal cortex might serve as basis functions with which the brain could compute the position of a visual target with respect to the head. Cells in this region of the brain typically have a discharge r that is modulated by both the position of the eye xe in the orbit and the position of the target on the retina xr. These cells have a preferred position on the retina where discharge is at a maximum, and this discharge is modulated approximately linearly with the position of the eye. Using a weighted sum of these functions, one could estimate position of the target with respect to the head: yˆ x, )x (11. However, Pouget and Sejnowski27 point out that because the tuning functions are the bases by Copyright © 2005 CRC Press LLC which the map is constructed, the same bases can be used to form any other representation — for example, a shoulder-centered representation of the target. This idea is important because it demonstrates that population coding, a method that can be used to form neural computations of identity maps, is equally suited to the more general problem of computing nonlinear maps. Another point is that whereas in the population code described for decoding of movement direction the weights were vectors that were static and pointed in the PD of a cell, here, if the bases are to be used for learning arbitrary maps, then the weight vectors will change and will have no speciﬁc relationship with the tuning function. Let us now return to our problem of how the brain might compute an internal model. One can think of an internal model as a map that transforms sensory input regarding the desired state of the arm x (i. Each neuron that participates in this computation has a tuning curve gi that describes the average discharge of that cell as a function of hand position and velocity. Consider the following experiment: participants are initially trained with force ﬁeld f1 for movement along arm state x1. The error that they experience in a movement changes the preferred force vector w. Assuming Hebbian learning rules, the weight change will be maximum for those neurons that happened to be most active at about state x1. The subject is then asked to make a movement with the arm along state x2, an arm position (or velocity) for which the subject has not been trained. If performance is different from naïve, then the function gi for which the weights adapted for movements along x1 must have been broad enough not only to be active for x1, but also for x2. Therefore, if the internal model is represented via a population code, then generalization is described by the shape of the tuning curves of the elements of computation.
People operating consistent anti-inflammatory cheap 100mg penegra, anti-fungal buy cheap penegra 100 mg online, anti-stress, and heavy equipment or working in situations that require a sedative effects. In one well-known study, extracts of high level of alertness should keep this in mind when ashwaganda root were shown to significantly increase using ashwaganda. Side effects Experimenters have had mixed results in demon- strating anti-tumor and anti-cancer properties of ashwa- No undesirable side effects have been reported with ganda. GALE ENCYCLOPEDIA OF ALTERNATIVE MEDICINE 2 135 OTHER KEY TERMS “Withania somnifera aphrodisiaca. Decoction—A liquid extract of a herb, made by simmering or boiling the herb in water, then straining out the plant parts. Poultice—A soft moist mass of cloth, usually con- Asthma taining herbs, applied warm or hot to relieve pain or speed healing in a part of the body. Definition Psoriasis—A skin disease characterized by dry, Asthma is a chronic inflammatory disease of the air- scaling, whitish patches. This inflammation periodically causes Scabies—A contagious skin disease caused by a the airways to narrow, producing wheezing and breath- mite and characterized by small, raised, red, very lessness sometimes to the point where the patient gasps itchy pinprick bumps on the skin. This obstruction of the air flow either stops spon- Tincture—An alcohol-based extract of a herb pre- taneously or responds to a wide range of treatments. Description Vegan—Food products made without any animal Between 16 and 17 million Americans have asthma products such as meat, milk, or eggs. Blacks, Hispanics, American Indians, and Alaskan na- tives had higher rates of asthma-control problems than whites or Asians in the United States. Interactions The changes that take place in the lungs of asthmat- ics make their airways (the bronchi and the smaller bron- There are few, studies of how ashwaganda interacts chioles) hyper-reactive to many different types of stimuli with traditional Western medicines. In an asthma attack, the many years in combination with other Ayurvedic herbs muscle tissue in the walls of the bronchi go into spasm, without incident. Ayurvedic practitioners believe that and the cells that line the airways swell and secrete when ashwaganda is combined with other herbs in reju- mucus into the air spaces. Both these actions cause the venation formulas, it enhances the effects of these other bronchi to narrow, a change that is called bronchocon- herbs. Resources Cells in the bronchial walls, called mast cells, release BOOKS certain substances that cause the bronchial muscle to con- Chevallier, Andrew. The American Pharmaceutical Association leukotrienes, also bring white blood cells into the area. New York: William Many patients with asthma are prone to react to substances Morrow and Company, 1999. Many people with asthma do not realize that aller- ORGANIZATIONS gens are triggering their attacks. While the symp- 136 GALE ENCYCLOPEDIA OF ALTERNATIVE MEDICINE 2 toms may be similar, certain important aspects of asthma are different in children and adults. When asthma begins INHALED ALLERGENS in childhood, it often does so in a child who is likely, for MOST OFTEN TRIGGERING ASTHMA ATTACKS genetic reasons, to become sensitized to common aller- gens in the environment. In 2004, scientists in Helsinki, Finland, Animal dander identified two new genes that cause atopic asthma.
From the perspectives of training and public perception generic penegra 100mg with mastercard, the potential advantages of simulation are improved surgical skill penegra 100 mg without prescription, minimization of surgical errors, and alterna- tives to learning on patients. They are typically animation-based or rely on photorealistic images to recreate the visual experiences of surgery. This involves substantially © 2005 by CRC Press LLC increased computational requirements and general assumptions about tissue charac- teristics. A popular technique for accomplishing this type of deformation is the use of mass-and-spring lattices to model surfaces of structures. Mathematical calculations can then be used to determine the degree of deformation associated with a particular force. While providing more physically realistic tissue behavior, the computational require- ments become substantially higher. The use of haptics in neurosurgical simulators lends an additional degree of realism and training potential. In each case, the visual feedback of an interactive experience is mechanically linked to a haptic device to provide an additional degree of realism and more accurately replicate the surgical experience simulated. Many of these concepts and approaches will become clinical therapeutics at some level and many will eventually be rejected after they are tested. Great laboratory ideas often flounder in the setting of clinical applicability when unanticipated consequences arise. The formats of clinical trials most likely to be implemented with the advent of new therapeutics were outlined in Chapter 15. One team member should be knowledgeable about the disease state to be treated and whether sufficient clinical interests or controversy exists to make a trial worthwhile. A team should also have a statistician or epidemiologist familiar with trial design who can help set up a suitable trial intended to answer the questions posed by the clinician. Such a trial may often involve multiple cooperating sites that are willing to rigidly follow a specific protocol. A neurosurgeon should remain at the heart of any team, both to provide the clinical rationale and experience in clinical testing schemes and identify questions most suitable for study. For devices there also needs to be a sponsor, such as an interested “enthusiastic” investigator, or more commonly, a corporate entity with commercial interests at heart. The sponsor is the liaison to the FDA for eventual approval and market release of the device (see Chapter 1). This group forms the minimum team needed to begin a clinical trial solution to a new product or device. However, one of the key com- ponents of such a team is the interested clinician, who can pose the critical problem, © 2005 by CRC Press LLC which the clinical study or device will resolve, and who is sufficiently enthusiastic to maintain the trial format through the large number of regulatory and funding hurdles. The clinician needs to convince the community of other clinicians that resolution of the problem requires a formal clinical trial, establishing equipoise and uncertainty about the relative worth of differing treatment options.
The chiropractic group fared slightly better (pain and disability) if the current episode was of less than 1 week penegra 50 mg generic, while physiotherapy was better if the episode had lasted longer than a month generic 100 mg penegra with mastercard. There were no significant overall differences 86 87 between the two treatment groups at 6 months or 1 year. Unfortunately, the authors did not evaluate data from the patients with neck pain independently from those with back pain, so specific conclusions cannot be drawn relative to cost or effectiveness for individual complaints. Other studies that have looked at the degree of satisfaction in patients seeking manipulative therapy or chiropractic care have reached a similar conclusion, demonstrating much higher patient satisfaction scores compared to other forms of treatment, including conventional medical 88 care. This may be due to the time spent by chiropractors with a patient, the simple laying on of hands, the personal attention offered patients by most chiropractors or the frequency of visits, which tend to be higher than for other treatments. The study by Pope and Complementary therapies in neurology 52 colleagues demonstrated increased satisfaction the longer the care continued, which 88 suggested that personal contact with the practitioner may be the overriding factor. COMPLICATIONS OF MANIPULATION Spinal manipulation, like all forms of treatment, can have side-effects. Nearly half of all patients who undergo spinal manipulation experience side-effects such as local 89,90 discomfort, headache, or tiredness. Up to the present, no serious complication has been reported in any of the controlled clinical trials or in any prospectively evaluated case series. The perceived risk of cerebrovascular injury following cervical manipulation has been a particular source of concern. The risk of vertebral artery dissection has been estimated 91 by various authors using different methodology to range from 1 in 400000 to between 3 and 6 per 10 million manipulations. These figures have been primarily based on 92,93 retrospectively collected single case reports and case series, and practitioner 91,94 surveys. There has been one retrospective cohort study that examined the incidence of 89 cerebrovascular accidents after manipulation. It covered the period 1978–88, and the experience of 99% of the practicing chiropractors in Denmark. Over 10 years, five arterial dissection cases and one fatality were identified, representing approximately one serious complication for every 1 million cervical manipulations. The only case-control 95 study published to date on this topic is that by Rothwell and associates. They concluded that no temporal relationship existed between spinal manipulation and stroke for patients over the age of 45 years. Under the age of 45 years there was a five-fold increased likelihood that a patient would have visited a chiropractor in the past week or received three or more treatments within the past month before the vertebral artery occlusion or dissection, when compared to controls. A positive association was noted between cervical manipulation and vertebrobasilar artery stroke in 1. Assuming that patients are likely to receive 8–14 chiropractic 6 treatments during the course of care, this number approaches the one in 500000 to 1 million manipulations noted from the various surveys. It is important to note that in only nine cases out of 582 with vertebrobasilar arterial strokes in the province of Ontario could any temporal association be found between chiropractic treatment and stroke. Furthermore, the results of this study yielded the statistical anomaly that the odds ratio for stroke was actually significantly less than in controls for patients who received manipulation 8–30 days before the stroke.