By K. Kamak. State University of New York College at Cortland.

Beta (b−)-Decay 15 222Rn → 218Po + a 86 84 The a-particles from a given radionuclide all have discrete energies cor- responding to the decay of the initial nuclide to a particular energy level of the product (including proven 5 mg eldepryl treatment e coli, of course quality eldepryl 5mg treatment goals for anxiety, its ground state). The energy of the a- particles is, as a rule, equal to the energy difference between the two levels and ranges from 1 to 10MeV. The high-energy a-particles normally origi- nate from the short-lived radionuclides and vice versa. The a-particles can be stopped by a piece of paper, a few centimeters of air, and gloves. In the b -decay process, a neutron is converted to a proton, thus raising the atomic number Z of the product by 1. Thus: n → p + b− + The difference in energy between the parent and daughter nuclides is called the transition or decay energy, denoted by E. The b−-particles carry max Emax or part of it, exhibiting a spectrum of energy as shown in Figure 2. This obser- max vation indicates that b−-particles often carry only a part of the transition − energy, and energy is not apparently conserved in b -decay. To satisfy the law of energy conservation, a particle called the antineutrino, , with no charge and a negligible mass has been postulated, which carries the remain- der of E in each b−-decay. In other words, b−-decay is followed by isomeric transition if energetically permitted. The decay process of a radionuclide is normally represented by what is called the decay scheme. The b -decay is shown by a left-to-right arrow from the parent nuclide to the daughter nuclide, whereas the iso- meric transition is displayed by a vertical arrow between the two states. Although it is often said that 131I emits 364-keV 131 g-rays, it should be understood that the 364-keV g-ray belongs to Xe as Fig. Eighty-one percent of the total 131I radionuclides decay by 364-keV g-ray emission. Approximately 87% of the total 99Mo ultimately decays to 99mTc, and the remaining 13% decays to 99Tc. This is true for all b−-, b+-, or electron capture decays that are followed by g-ray emission. Some examples of b−-decay follow: 99 99m − 42Mo → 43Tc + b + 131I → 131Xe + b− + 53 54 67Cu → 67Zn + b− + 29 30 90 90 − 38Sr → 39Y + b + It should be noted that in b−-decay, the atomic number of the daughter nuclide is increased by 1 and the mass number remains the same. Positron emission takes place only when the energy dif- ference (transition energy) between the parent and daughter nuclides is 18 2. In b -decay, essentially a proton is converted to a neutron plus a positron, thus, decreasing the atomic number Z of the daugh- ter nuclide by 1. Some examples of b+-decay follow: 18F → 18O + b+ + 9 8 68 68 + 31Ga → 30Zn + b + 13 13 + 7N → 6C + b + 15 15 + 8O → 7N + b + + The energetic b -particle loses energy while passing through matter. When it loses almost all of its energy, it combines with an atomic electron of the medium and is annihilated, giving rise to two photons of 511keV emitted in opposite directions. The positrons are annihilated in medium to give rise to two 511-keV g-rays emitted in opposite directions. Thus, p + e− → n + In this process, the atomic number of the daughter nuclide is lowered by 1. Radioactive Decay the transition of an electron from the next upper shell, in which case the difference in energy between the two shells appears as a characteristic x-ray of the daughter nuclide. Also, as described earlier, instead of charac- teristic x-ray emission, the Auger process can occur, whereby an Auger electron is emitted. If the energy difference between the proton-rich parent nuclide and the + daughter nuclide is 1. If the total conversion coefficient (aT) of 195-keV g-rays of a radionu- clide is 0.

Estimation of the benefit of bone- ence with skin-penetrating bone-anchored implants in the tem- anchored hearing aids buy generic eldepryl 5mg line treatment 3 cm ovarian cyst. Its cen- difficulties that may be encountered in implanting various inner tral axons pass through the lamina cribrosa to form the cochlear ear dysplasias generic eldepryl 5 mg amex 88 treatment essence, the risks that might be encountered, and results nerve, which passes through the internal auditory meatus that might be expected. The main determinant of pitch in the of our knowledge, therefore, this chapter must of necessity be normal inner ear, therefore, is the point along the cochlear par- somewhat rudimentary. Nevertheless, generalisations can be tition where maximum depolarisation of the hair cells occurs. The risks associated with comorbidity in addition, some frequency information is conveyed by alteration certain deafness syndromes are touched upon. Children born deaf or deafened in the first years of hearing loss is usually the result of hair cell loss in the organ of life, however, have had no access to sound and have usually Corti and the causes are many. In the normal inner ear, the acquired very little in the way of spoken language; they may organ of Corti acts a transducer that converts the travelling have faced a life of social, educational, and professional isola- wave in the inner ear fluids to electrical activity in the cochlear tion and often economic hardship. The cochlear implant has nerve; this then progresses through the brainstem centres of the changed things in a quite spectacular manner and has trans- auditory pathways to the higher centres, the primary auditory formed the lives of many thousand deaf people since its intro- cortex and the association areas. A multichannel electrode array is inserted into the reduced penetrance and variable expression (1). The specific genes worldwide has a series of 22 electrodes mounted on a silastic within these loci have not as yet been identified or cloned. The stimulation strategy takes advantage of the tono- addition, there is emerging evidence that postnatal exposure to topic arrangement of the cochlea. The most distal electrodes paramyxoviruses, particularly measles, in sporadic or genetically deliver low-frequency information and those in the basal turn predisposed individuals is part of the process leading to clinical deliver high frequencies. Most cases present with a conductive hearing loss stimulate the spiral ganglion cells or possibly surviving distal that may be managed by stapes surgery, but, in severe retrofen- dendrites and performance with the implant is related to the estral disease, there may be a profound cochlear loss, and this ganglion cell population. There may be partial obliteration of the signal from the external transmitter and a stimulator contain- scala tympani by otosclerotic bone necessitating a drill-out, but ing a microchip that directs electrical stimuli to the appropriate usually the extent of new bone formation is confined to the first electrode at a rate that may be as high as 90,000 times per few millimetres of the basal turn and the problem is easily second. More The internal component is inserted during an operation of an issue is the spread of current from the array through that usually takes about one to two hours. The middle ear is the otospongiotic bone of the otic capsule to the facial nerve entered through a transmastoid facial recess approach and a causing twitching of the face. This is most likely to be caused by small cochleostomy is drilled in the promontory just in front of electrodes close to the first genu of the nerve. It is managed by the round window to allow access to the scala tympani of the removing the rogue electrodes from the map but, as time goes basal turn. The electrode is threaded in and the receiver stimu- by, it is not uncommon for more and more electrodes to have to lator is located in a shallow bony well in the skull just above be deactivated, as demineralisation of the otic capsule proceeds, and behind the pinna. The external component comprises a so that eventually the device may become unusable (7). The microphone, a signal processor, and a transmitter that sends the other problem that can occur is result of osteolysis and cavita- processed signal through the skin to the internal component tion in the petrous bone; the electrode may become displaced encoded on to a radiofrequency carrier wave. These cases are usually associated with chronic middle ear disease, autoimmune inner ear disease, and severe hair cell loss but usually with good preservation of the surgery. As expected, both types are char- these recipients acquire good open set speech recognition and acterised by maternal inheritance.

Medication is generally prescribed to induce regular menstruation order 5 mg eldepryl fast delivery treatment 12mm kidney stone, thereby reducing the cancer risk discount 5mg eldepryl with amex symptoms 4 dpo. For polycystic kidney disease An inherited disor- acne and excess hair growth, the diuretic medication der that is characterized by the development of spironolactone (brand name: Aldactazide) can help. Surgical The cysts eventually reduce kidney function, leading procedures involving the removal or destruction of a to kidney failure. Treatment involves managing pain and affected women contain a number of small cysts. Polycythemia can lead to heart failure, stroke, and polycystic kidney disease, adult See polycys- other medical problems when severe. Other features of the disease can leukemia or myelofibrosis, in which the marrow is be cysts in other organs, such as the liver and replaced by scar tissue. Polydipsia occurs in untreated or sive An early-onset disorder that is characterized poorly controlled diabetes mellitus. For example, eye color is polyneuritis, acute idiopathic See Guillain- polygenically controlled because many genes are Barre syndrome. The flat areas of increased skin pigment are called polyhydramnios Too much amniotic fluid. See also sleep polymyositis An autoimmune inflammatory dis- apnea; sleep apnea, central; sleep apnea, ease of muscle that begins when white blood cells obstructive; sleep disorders. Blood testing in a person with polymyositis shows Pompe disease An inherited deficiency of the significantly elevated creatinine phosphokinase lev- enzyme alpha-glucosidase which helps the body els. The diagnosis is further suggested by elec- break down glycogen, a complex carbohydrate that tromyogram testing and confirmed with muscle is converted to glucose for energy. Treatment of polymyositis requires high enzyme, glycogen builds up in the heart and other doses of cortisone-related medications, such as muscles, causing extensive damage. There are sev- prednisone, and immune suppression with medica- eral different forms of Pompe disease which vary in tions, such as methotrexate and cyclophosphamide. Due to popliteal pterygium syndrome An inherited an abnormal aggregation of capillaries, a port-wine condition that is characterized by a web (ptery- stain is a type of hemangioma. See also popliteal pterygium syndrome are cleft palate (with Sturge-Weber syndrome. The opposite of posterior is in an autosomal dominant manner and is due to anterior. See also Appendix B, “Anatomic mutation of the interferon regulatory factor 6 gene. Most porphyrias affect the skin or the nerv- with the chest against the film plate and the X-ray ous system. See patient may suffer rapid heartbeat, mania, muscle also Appendix B, “Anatomic Orientation Terms. Acute attacks are often pre- postherpetic neuralgia See neuralgia, pos- cipitated by the use of certain drugs, such as therpetic. One type of porphyria, acute intermittent occurs together with balanitis, inflammation of the porphyria, may have affected members of the House glans, as balanoposthitis. See also balanitis; bal- of Hanover in England, including “Mad” King anoposthitis. Normally, the veins from the stomach, intestine, spleen, and pancreas postmenopausal After menopause, the period merge into the portal vein, which then branches into of time after a woman has experienced 12 consecu- smaller vessels and travels through the liver. It can cause gastrointestinal bleeding, back of the nose and throat that leads to or gives the ascites, and symptoms related to decreasing func- sensation of mucus dripping down from the back of tion of the liver.

Nonethe- nature of their etiology is not fully understood less discount eldepryl 5mg visa medicine 0031, despite issues with diagnostic criteria cheap eldepryl 5 mg amex treatment quietus tinnitus, a review (Popovsky and Camisa, 2000). The complexity of of studies in the area leads to the conclusion that the etiopathogenesis of these conditions is illustrat- patients with some forms of lichen planus are at risk ed by aphthous stomatitis, which is the most com- for developing oral cancer. If the estimated frequency of lichen planus Some of the infections seen in immunocompromised is 1%, then among that age group there are 510,000 patients were, hitherto, very unlikely to be seen by cases of lichen planus. Herpes viruses are char- the issue of lichen planus as a premalignant lesion acterized by their ability to establish latent infec- needs to be better defined and studied. It seems like- tions that can be reactivated, especially in the ly that not all forms of lichen planus are at equiva- immunocompromised patient (Oakley et al, 1997). For many of these condi- ulcers are most frequently found on keratinized tions, current treatment is palliative and/or anti- mucosa (Regezzi and Sciubba, 1989). New immunosuppressed patients can develop lesions at molecular biological techniques, the definition of any intraoral site, with nonkeratinized sites repre- the human genome, and the association between senting half of all sites involved (Woo and Lee, specific genes with effector proteins should lead to a 1997; and Oakley et al, 1997). Oropharyngeal candidiasis is perhaps the most frequently encountered fungal Other Infections infection and constitutes a major cause of morbid- ity and mortality in immunocompromised patients The mouth is home to a great variety of organ- (Lynch, 1994; and Phelan et al, 1997). Fortunately, the majority of these are not of patients the organism isolated is Candida albicans any serious health consequence. Nevertheless, (Odds et al, 1989), but in recent years other knowledge about infectious agents and their natural Candida species such as Candida glabrata are histories is essential for the practicing dentist. Unfortunately, infections and be aware of the role of the "carrier" the widespread long-term use of fluconazole in (an apparently healthy individual who shows no recent years has lead to the development of resist- sign of an infectious disease but is able to transmit ance of oral isolates to azole drugs and, in some the disease to others). Federal and mouth are related to Treponema pallidum, state regulations have been formulated which can Mycobacterium tuberculosis and Neisseria gonor- lead to monetary fines and other sanctions if these rhae. These include tions have a low incidence, but in some regions of the widespread use of agents that suppress the the United States certain fungal infections are epi- immune system, as well as immunosuppressive demic (i. Saliva modulates oral microbial ecosystems, aids More than 300 medications can cause oral dry- in the preparation of the food bolus, lubricates oral ness, and certain classes of medications are more tissues, and supports other critical oral functions. The initial phases of dental caries development are These include sedatives, antipsychotics, antide- reversed in part by saliva, which buffers acids and is pressants, antihistamines and certain anti-hyper- supersaturated with calcium and phosphorus. Medi-cations with anticholinergic salivary mucins are a heterogeneous population of activity can potentially decrease salivation glycoproteins that bathe and protect oral soft tissues (Atkinson and Fox, 1992). Any patient with salivary gland dysfunction The most pronounced salivary dysfunction occurs will benefit from an aggressive oral hygiene pro- in three groups of patients: gram that includes the use of topical fluorides (Ripa, 1989). The use of pilocarpine and the oxygen searchers primarily use one of three sets of crite- radical scavenger amifostine during radiation ria to select patients for studies (Fox, 1997). This treatment may decrease damage to glands (Valdez lack of uniformity in patient selection represents et al, 1993; and Jha et al, 2000). The availability in the last decade of systemic x Patients who have received therapeutic radiation agents that can stimulate salivary output to the head and neck. At doses above 40 Gy, the damage is rapid however, they have significant side effects that and irreversible, and the mechanisms for this unfor- limit their utility and patient acceptance. Eval- out malocclusions, joint anatomy, and skeletal mal- uation should encompass examination of orofacial formations as significant etiological factors. However, the consid- Le Resche, 1992); however, its clinical utility and eration of psychosocial factors has the potential for validity as a research tool have not been established. Surgical approaches may be necessary in a known why some patients progress and others do not.