By X. Angar. Indiana University - Purdue University, Columbus. 2019.
Pharmaceutical companies followed Carlsson’s lead to find serotonin-enhancing drugs and in the 1970s serotonin reup- take inhibitor antidepressants were born buy nizagara 25mg otc tobacco causes erectile dysfunction. Prescribing antidepressants has risen nearly 400% since 1988 in the United States; more than 1 in 10 Americans over age 12 now takes an antidepressant order 25 mg nizagara visa erectile dysfunction 37 years old. Attention-deficit/hyperactivity disorder positive feelings about others cheap 50 mg nizagara free shipping erectile dysfunction treatment edmonton, and ability to meet 5. Autism spectrum disorders the world as the authoritative guide to the diag- nosis of mental disorders. Mental physical wellness, which will aid in positive energy levels and disorders are usually associated with significant clarity of mind. Exercise: distress or disability in social, occupational, or O Releases endorphins. Suicide was the yourself to accomplish your daily goals and reaping the 10th leading cause of death in the United States benefits of those accomplishments. According to the World Health Organi- Think Critically zation, more than 450 million people worldwide 1. Promote Your Health Mental Health Tips Just as in physical health, there are actions you can take to 3. Helping someone can put your problems into perspective increase your mental health: and make you feel valued. Chapter Fifteen Mental Disorders L 341 Risk Factors Table 15–2 early Warning signs A variety of risk factors can impact mental and symptoms health; being aware of potential risk factors can of Mental Disorders aid in maintaining good mental health. Genes may influence the development of some Withdrawing from friends and family mental disorders; therefore having a parent or Dramatic changes in eating or sleeping habits sibling with a mental disorder may increase the risk of developing a mental disorder. Environ- Deterioration in personal hygiene mental factors such as damage from exposure Confused thinking to alcohol, illegal drugs, infection, toxins, brain injury, oxygen deprivation, and poor nutrition Prolonged sadness may negatively affect the development of the fetus and may contribute to the onset of mental Decreased ability to concentrate disorders. Children that experience stress from A drop in school or work performance poverty, abuse, and neglect may be vulnerable to developing mental health disorders. Expe- Decrease in motivation riencing brain damage as a result of a serious Irritability brain injury may increase the risk of developing mental disorders. Traumatic life events such as Moodiness the death of a parent, war, or a tragic accident Increased anxiety or agitation can have a traumatic effect on emotional well- being. Chronic or disabling illness can cause Unusual ideas or beliefs isolation and loss of necessary support from Mistrustfulness or suspiciousness family and friends. Alcohol and drug abuse may cause or exacerbate preexisting mental health disorders. It is believed that mental disorders are associated with abnormalities in several genes. Symptoms of Mental Disorders This is the reason why the person inherits the vul- Mental disorders rarely come on suddenly. Most nerability to develop a mental disorder but does often family, friends, teachers, or coworkers- not inherit the mental disorder itself. Brain defects, even the individual him- or herself-recognize injury to certain areas of the brain, or trauma to that something is wrong with the person’s think- the brain at the time of birth may lead to mental ing, feelings, or behavior. Disruption of fetal brain development early warning signs of mental disorders can aid from alcohol or drug use or certain infection may in intervening to possibly delay or prevent the be a factor in the development of mental disorders. If several of the signs or symp- An imbalance of neurotransmitters, chemical sig- toms in Table 15–2 are occurring, a mental nals that help brain cells communicate, may be disorder may be developing. People who have gone through Causes of Mental Disorders emotional, physical, or sexual abuse, neglect, Determining the cause of a mental disorder bullying, or domestic violence may not be able is very challenging. Certain envi- typically arise from an interaction between ronmental stressors such as poverty, living in biological, psychological, and environmental a difficult and unsafe environment, a dysfunc- factors. A physical examination and psychiatric medications include antidepressants, laboratory testing rule out an underlying medical mood stabilizers, anti-anxiety medications, stim- condition as the etiological agent of the signs and ulants, and antipsychotics. Laboratory testing may include blood contact with reality that usually includes delu- tests, imaging tests, urinalysis, hormone testing, sions (false beliefs about what is taking place or and electroencephalogram to measure and record who one is) and hallucinations (seeing or hearing the electrical activity of the brain. The inter- recommended when patients can’t care for them- view will cover a wide range of topics. Additional assessment may include nia or excessive sleep; change in appetite; personality, reasoning, aptitude, and intelligence difficulty concentrating, thinking, or making quotient testing. Psychotherapy helps physical examination, laboratory testing, and patients understand the behaviors, emotions, comprehensive psychiatric evaluation. Treat- and ideas that contribute to their mental disor- ment may include antidepressant medications, der. The knowledge and insights gained during psychotherapy, electroconvulsive therapy, and psychotherapy help patients manage the signs other brain stimulation therapies. Behavior Observed: Mannerisms, expression, eye contact Attitude Observed: Pleasant, cooperative, agitated, hostile, open, secretive, evasive, suspicious, apathetic, easily distracted, focused, defensive Level of consciousness Observed: Is the patient conscious? Speech and language Observed: Are speech and language normal in tone, volume, and quantity? Thought process Observed/inquired: Are the patient’s responses to general questioning logical, relevant, and organized? Are there thoughts or images you have a really difficult time getting out of your head? Does it ever seem like people are stealing your thoughts or perhaps inserting thoughts into your head? Suicidality and homicidality Inquired: Do you ever feel that life isn’t worth living? Do you think about hurting others or getting even with people who have wronged you? If you found a stamped, addressed envelope on the street, what would you do with it? Attention span Observed/inquired: I will recite a series of numbers to you, and then I will ask you to repeat them to me, first forward and then backward. Starting with 100, subtract 7 from 100, and then keep subtracting 7 from that number as far as you can go. I am going to ask you to remember three words and I will ask you to repeat them to me in 5 minutes. Intellectual functioning Observed/inquired: Name the current president and vice president. It is a myth that depres- estimated prevalence of paranoid personality sion is part of the aging process. Many senior citizens • Schizoid personality disorder-They are think that depression is a character flaw. They themselves for their depression and are too ashamed to get are often distant, detached, or indifferent to help. People with this dis- Personality Disorders order usually have cognitive or perceptual distortions as well as eccentricities in their A deeply ingrained, inflexible pattern of relat- everyday behavior. The estimated preva- ing, perceiving, and thinking that is serious lence of schizotypal personality is 5% of enough to cause distress or impaired function- adults in the United States. Personality • Obsessive–compulsive personality dis- disorders occur in approximately 9% of adults order-They have a preoccupation with in the United States.
If a photomultiplier-type sorbs some of the energy in the x-ray beam phototimer is used purchase nizagara with visa erectile dysfunction vacuum pump reviews, the phosphor in the and stores a portion of this energy as va fuorescent screen used to convert x rays lence electrons stored in high energy traps to light should be matched to the phosphor to create a latent image nizagara 100mg mastercard purchase erectile dysfunction pump. The photomul image is scanned by a laser beam buy nizagara 25 mg without a prescription erectile dysfunction caused by sleep apnea, the tiplier tube selected should be sensitive to trapped electrons return to the valence the light output of the phosphor. This light tion chamber-type phototimers can be is viewed by a photomultiplier tube, and made to work satisfactorily. The signal is fed to a diography (photostimulable suggests that computer where it is processed and stored, luminescence is going to be induced by ab and may be displayed in any of the normal sorption of light photons). This technology is sometimes The material used in one commercially called "filmless," or "electronic," or "com available photostimulable phosphor is eu puted" radiography. Luminescent The reason for using an activator is to materials can absorb energy, store a frac make traps at the activator site in the crys tion of it, and convert the energy into light, talline structure. These traps that are determined by the time it takes for are localized energy levels at the activator light to be emitted after an exciting event or vacancy site that do not normally exist takes place. This oc electron is captured in the trap, it behaves curs when an electron is excited from one very much like an electron trapped energy level, and then returns to that en (bound) in an atom. We remember that to ergy level without anything additional hap remove an electron bound to an atom, we pening to it. This delay produce a positive ion (which is the atom requires some additional interaction of the without an electron) and an electron that electron; normally this is described as a is free to move away from the atom. The trapping of the electron in some localized same is true for an electron that is trapped energy state. If we want from fuorescent material that emits its to free the electron from the trap, we must light immediately after stimulation. This is supply it with sufficient energy to free itself just fne, because flm is there to capture from the trapping mechanism. However, if we would like the ply the energy, the electron is free to move screen to retain the x-ray image, we would through the crystalline structure, and it use a phosphorescent material. In radiol leaves behind an empty trap (that looks like ogy, there are two such applications. A photostimulable phosphor is a which the phosphor is encouraged to emit material that has activator and vacancy its light by heating. A thermoluscent do traps from which electrons may be re simeter is a small chip of activated lithium moved by absorbing energy from light fuoride that is exposed to radiation. Without looking further into the chip is then heated, and emits light in pro physics of trapping mechanisms, we will portion to the amount of radiation it re describe how a photostimulable phosphor ceived (the term "thermoluminescence" in plate is used in clinical radiography. We have no de The plate is now exposed to x rays, using sire to get into the physics of such things standard radiographic equipment. The toelectric effect and create a high-energetic rest of the excited electrons are trapped photoelectron. The photoelectron in turn, through a cascade process, generates a large and form the latent image. The thermal agitation of elec the electron-hole-pairs recombine at euro trons out of the traps will degrade the la pium centers during the x-ray exposure and tent image. The other half of the image should be retrieved as soon as pos electrons and holes are trapped separately, sible to prevent degradation due to thermal holes at divalent europium sites, electrons at agitation. The local concentration of The image is retrieved by putting the trapped holes and electrons is proportional imaging plate in a reader. The reader is to the local x-ray exposure and represents the made so that the plate is scanned by a small latent image of the x-rayed object. The electrons may migrate to trapped holes and recombine The trapped electrons exposed to this with them to generate europium lumines small dot of laser light will absorb the laser cence. This addition of energy will ulating light, the phosphor screen is actually free the electrons from their traps, and prepared with a very high, uniform and sta they will become free to return to the lower ble concentration of trapped electrons at hal ogen vacancies. Obviously, by stimulation energy state associated with the crystalline with (red) light, the latent image is destroyed. Note that the crystalline state of the lattice structure has a lower energy level Photostimulable Phosphor Imaging than the electron trap. When the electrons Let us now look at the process of pho return to this lower energy level they will tostimulable phosphor (or computed ra emit a light photon. This That the two lights (the laser light and means that the amount of photostimulable stimulated emission) have different wave luminescence created by an exposure in lengths is critical for image retrieval. After creases, or decreases, in direct proportion all, we have an intense red laser light and to the amount of x-ray exposure the phos a somewhat feeble greenish light in the phor receives. The actual exposure range same vicinity, and we would like to detect over which this linear response is seen cov the greenish light as the image signal. One ers a range of about 5 microroentgens (5 way to do this is to use a flter that will x 10-3 mR) to about 50 milliroentgens (5 absorb the red light but be transparent to X 101 mR), yielding an exposure range of the greenish light. Figure 9-14 is a rough use an optical fber, we can conduct the graphic representation of this concept. No signal light to a photomultiplier tube at a tice that as the exposure increases from 5 remote position so that the photomultiplier X 10-3 mR to 50 mR (horizontal axis of tube and the laser light do not interact. The entire plate can be to take a glance ahead to Figure 11-5 and read, a scan at a time, by moving the image notice that flm has a more narrow dynamic plate perpendicular to the scan line of the range, and a non-linear response to ex laser beam. This concept of dy tube, we have a continuous point-by-point namic range (we will often call this "ex scan of the image. The output is an elec posure latitude") will be re-examined in trical analog signal corresponding to ab much more detail in Chapter 11. This signal What is the advantage of a system with must be amplifed, converted to a digital a large, linear dynamic range? That is, the exposure that : i w ( causes the flm to be developed as very a 0 I 100 black is about 100 times greater than the 3 2 1 ° 1 2 � 10- 10- 10- 10 10 10 exposure that causes such a faint gray that c. The A major problem in radiology departments newer fast phosphors exhibit a higher con results from the need for repeat exami version effciency. A rays in the diagnostic range is a function wide latitude system will decrease the need of the matching of the K-absorption edge for repeat exposures. The spectral emis: necessary to process photostimulable phos siOn of some phosphors requires that an phor �mages in two steps. System noise becomes important alyzed to compute the exposure level and when the fastest flm-screen systems are exposure range of the stored image. This pre-reading activated banum fuorohalide, which is thus allows examinations made with a wide coated on an imaging plate. The latent image is con underexposed and overexposed as well as verted to a light image using laser stimu correctly exposed examinations will be lated luminescence. Digital tube conve ts the: light image intoan analog processing of these images can produce a. This analog signal is am vanety of other image changes which we plifed, converted to a digital sig�al, and will consider in another chapter. Also, the lower expo method for the evaluatwn of the conversion ef sures required (less mAs) allow the shorter fciency of fluoroscopic screens.
Gambusia is a Fenitrothion purchase nizagara with paypal how to cure erectile dysfunction at young age, Carbamates (propoxure and surface feeder cheap nizagara 100 mg mastercard cheap erectile dysfunction pills uk, hence it is suitable for feeding on bandiocarb) and synthetic pyrethroids generic 25mg nizagara with visa erectile dysfunction what doctor to see, etc. The synthetic pyrethroids to provide protection during toxins formulation may be used in water or for the entire transmission season. Flights are short and jerky be the insecticide of choice for residual spray where it as they are too weak to fly against wind (Fig. Out of about 39 species of sandflies found 1997 due to environmental concerns and partly due in India, those of medical importance are Phlebotomus to resistance. Diseases Transm itted The various types of formulations used for sprays The sandflies are responsible for the transmission of kala- are described later under the section Insecticides. Genetic Control Males sterilized by gamma irradiation and Control chemosterilants are released. They mate with females • Breeding is prevented by filling cracks and cervices but the later produce unfertilized eggs which do not on the walls and removing any stone or rock piles. This is a potentially useful method that • The adults are killed by indoor residual spray has yet to be tried on a large scale. They are They belong to family glossinae and are limited to applied to the exposed parts of the body. They are brown in color and have the • Preventing entry into houses: Mosquito-proof wire same size as a house fly. Both male and female bite man gauze (6 mesh) is used for this purpose on doors, and suck blood. Two species transmit trypanosomiasis: • Sleeping in mosquito nets: (6 mesh) and using veils, 1. Flies Though less important than mosquitoes as vectors of disease, the flies have a large variety of species. The proboscis of sandflies is like a blade and not like a stylet as in case of 114 mosquitoes. Insecticides used are organophosphorus compounds, They shun sunlight and come out at night. Pupa (Chrysalis): It is barrel shaped and about six They are of the size of a mosquito. An adult fly sucks, regurgitates, mixes, sucks again and vomits out the liquid food. Infection is carried by parts are adapted not to pierce the skin but to suck mechanical transmission (along legs, wings, body) and liquids and small particles. They are also called filth flies by deposition of vomit and feces on food and drink. Other important species found in India are The housefly can potentially transmit a large number of M. Maggots may invade human tissues and It is completed in 4 stages-egg, larva, pupa and adult, produce gastrointestinal, genitourinary or cutaneous myiasis, and takes 10 to 14 days. Eggs: They are laid five to six times in life, in batches of 100 to 200 on excreta and other soft, moist and Fly Control M easures warm filthy matter, especially horse litter. Glistening white in color and about one millimeter in size, the Elimination of breeding places: eggs, look like tiny grains of polished rice when seen • Sanitary disposal of wastes such as refuse (especially with the help of a hand lens. Actively • Food sanitation such as keeping all foods in wire gauze or glass cupboards and containers with well fitting lids. Prevention of entry: Making the houses flyproof, especially the kitchen and latrines, by putting wire gauze screens in doors and windows. Trapping: Using a Balfour fly trap made of wire gauze in which the flies enter through a slit to sit on the bait but cannot come out. Examples are: • Adhesive fly paper: 500 g castor oil and 800 g resin Tunga penetrans or sandflea: It is found in the are heated together and the mixture is spread on tropical parts of America and Africa. Flea indices6 are helpful in indicating the potential for • Tangle-foot paper: Glue 1 part in 3 parts of water epidemic spread of plague in and around areas where this is spread on a paper which is placed in an arched disease is endemic. The general flea index refers to the average number of • Strings and branches of trees: They may be dipped fleas of all species present per rodent. The specific flea in sugar or jaggery solution containing a toxicant index similarly pertains to particular species of fleas. They are laid in batches of 8 to 12 in the debris in the Liquid baits consist of 0. Houseflies have become resistant to residual Larva: It is a white, active, legless maggot with scanty spray with almost all insecticides-chlorinated hair on the segments of the body. It lives in dust and hydrocarbons as well as organophosphorus and feeds on the debris and feces of the adults. It may be mentioned that larvicidal Adults: After emerging, they get onto the hosts as spraying at breeding sites of housefly is not wingless insects. The reason is that this leads to suckers and the beak is provided with a siphon tube development of insecticide resistance. The foot has five joints, the Health education of individuals, families and the last of which has a hook as an adaptation for jumping. Fleas They belong to the order Siphonaptera and have laterally flattened body but no wings. These are listed below: Pulex irritants or human flea: It is cosmopolitan in habitat. The body louse lays about 6 eggs • Rats, mice and other hosts should be killed and other a day and sticks them onto clothes, especially in the antirodent measures adopted. Nymph or larva: The eggs hatch in about a week • For plague control the floor, walls (up to one meter into nymphs or larvae which resemble the adults. Adults: Gray in color and 2 to 3 mm long, they carbaryl are used in resistant cases. They can live for a • Burrows and rat-runs should be insufflated with 10 week without feeding. It bears a blood sucking malathion 5 percent may be dusted where fleas have proboscis and two antennae. It is found in pubic and perineal also as a collateral benefit because of the killing of hair. Diseases Transmitted • Contact with hosts, especially field rodents, should be avoided to prevent sylvatic plague. These are blood sucking insects with a dorsoventrally The crab louse is not known to transmit any disease. Both sexes live on the • The head and body lice also transmit Borrelia host itself. Other organophosphorus comb, hair brush and clothes of an infested person insecticides and carbamates are effective.
Radiation exposure during infancy has been linked to which one of the following carcinoma? Which among the following is not a neoplastic virus: (a) Cytomegalovirus (Bihar 2006) (c) Clonorchiasis (b) Hepatitis B virus (d) Schistosomiasis (c) Human papilloma virus 82 cheap generic nizagara uk erectile dysfunction medication nz. Physical examination reveals a large mass involving (a) Prevents formation of pyrimidine dimers the right side of his liver buy nizagara now erectile dysfunction treatment testosterone replacement, and a biopsy specimen (b) Stimulates formation of pyrimidine dimers from this mass confrms the diagnosis of liver cancer (c) Prevents formation of purine dimers (hepatocellular carcinoma) purchase nizagara amex erectile dysfunction emedicine. Which of the following (d) All of the above substances is most closely associated with the pathogenesis of this tumor? The most radiosensitive cells are: (a) Afaxotin B1 (a) Neutrophils (b) Lymphocytes (b) Direct-acting alkylating agents (c) Erythrocytes (d) Megakaryocytes (c) Vinyl chloride 82. One of the following leukemia almost never develops smoker Akki demonstrates glands containing cells with after radiation? With (b) Chronic myeloid leukemia which of the following infectious agents has this type (c) Acute lumphoblastic leukemia of lesion been most strongly associated? Which of the following bio markers he develops generalized lymphadenopathy with would be most useful for follow-up of patient? Which of the following tumors have an increased (d) Chondroblastoma elevation of placental alkaline phosphatase in the serum as well as a positive immunohistochemical staining for 86. An undifferentiated malignant tumor on (d) Pelvic immunohistochemical stain shows cytoplasmic (e) Vertebrae positivity of most of the tumor cells for cytokeratin. A 65 years old male diagnosed by biopsy a case of lung carcinoma, with paraneoplastic syndrome and 115. Which one of the following is a frequent cause of serum (c) Calcitonin alpha- fetoprotein level greater than 10 times the normal (d) Calcitonin related peptide upper limit? Workup reveals that no bone (c) Submucosa metastases are present, but laboratory examination (d) Appendix reveals that the man’s serum calcium levels are 11. Marker for ovarian carcinoma in serum is: woman Nusheen is noted to have a ruddy complexion. Which of the following is a marker for carcinoma of (a) Breast (b) Colon lung and breast? Secondaries of all the following cause osteolytic lesions and alternating diarrhea and constipation. Physical examination demonstrates hyperpigmentation of except: skin, even in areas protected from the sun. Tumor (a) Prostate (b) Kidney involvement of which endocrine organ is most strongly (c) Bronchus (d) Thyroid suggested by this patient’s presentation? Which of the following mutation is seen in malignant abdominal and back pain, malaise, nausea, 8 kg weight melanoma? Which of the following is a special stain for emergency room with a pathologic fracture of the shaft rhabdomyosarcoma? X-ray studies demonstrate multiple (a) Cytokeratin (b) Synaptophysin lytic and blastic bone lesions. Biopsy of one of these (c) Desmin (d) Myeloperoxidase lesions shows adenocarcinoma. The most common cause of malignant adrenal mass is (a) Breast (b) Colon (a) Adrenocortical carcinoma (c) Kidney (d) Lung (b) Malignant Phaeochromocytoma (c) Lymphoma Most Recent Questions (d) Metastasis from another solid tissue tumor 123. Tumor that follows rule of 10 is: brain in (a) Pheochromocytoma (a) Breast (b) Lung (b) Oncocytoma (c) Kidney (d) Intestines (c) Lymphoma (d) Renal cell carcinoma 123. The latter are sharply demarcated lesions that may be impossible to distinguish from follicular adenomas on gross examination. This distinction requires extensive histologic sampling of the tumor-capsule-thyroid interface, to exclude capsular and/or vascular invasion. Extensive invasion of adjacent thyroid parenchyma makes the diagnosis of carcinoma obvious in some cases’. Follicular Carcinoma: brushing up key points • It is the 2nd most common form of thyroid cancer • Seen in women of older age (40-50 yrs. Uncommonly, cells have abundant, eosinophilic cytoplasm called as Hurthle cellsQ • Differentiation from follicular adenoma is based on the presence of capsular invasion preferably and not on vascular invasionQ. Fibromatosis Superfcial Fibromatosis Deep Fibromatosis *Palmar fbromatosis (Dupuytren contracture) *Also called desmoids tumors *Plantar fbromatosis *Greater tendency to recur *Penile fbromatosis (Peyronie’s disease) *Grow in a locally aggressive manner *Arise isolated or as component of Gardner syndrome 3. However, they behave quite differently Normal cell Cancer cell Show replicative senescence i. It Cancer cells in culture produce telomerase may caused by inability to synthesize telomerase Normal cells show the phenomenon of contact inhibition i. Even after the surface of dish is covered, they proliferate until the surface of culture dish is covered by the cells continue to divide single layer of cells just touching each other Nutrients and growth factors must be supplied to them in their Do not require growth factors tissue culture medium Normal karyotype is present Mostly show abnormal karyotype 4. Ans (d) Muscle tumor cells forming giant cells (Ref: Robbins 8th/262-5, 9/e p270) Neoplastic cells may be similar to normal cells found in the tissue of origin, which defnes the malignancy as “well differentiated” or “low grade. Features of Anaplastic tumors • Loss of cell polarity and normal tissue architectureQ • Signifcant variation in shape and size of cells (cellular pleomorphism)Q • Deep staining of nuclei (hyperchromatismQ) and nuclear pleomorphism • Larger nuclei than those found in normal cells of the same tissue (high nucleus-to-cytoplasm ratioQ) • Numerous often abnormal mitosesQ • Giant multinucleated tumor cellsQ The appearance of giant multinucleated cells in a muscle tumor would therefore suggest anaplasia. Therefore a hepatic tumor that synthesizes bile is described as being well-differentiated not anaplastic. Therefore an epithelial tumor that produces keratin pearls would be described as well-differentiated not anaplastic. Features that characterize familial cancers includeQ 162 Neoplasia • Early age at onsetQ • Tumors arising in two or more close relatives of the index caseQ • Sometimes multiple or bilateral tumorsQ Familial cancers are not associated with specifc marker phenotypesQ. Mnemonic: Staging includes Size (extent of disease) and Spread (distribution) of the tumor. Very malignant-appearing tumors may not metastasize and benign-appearing tumors may produce metastases. Several histologic features, such as numbers of mitoses, confuent tumor necrosis, and spindle cell morphology, have been associated with an aggressive behavior and increased risk of metastasis, but these are not entirely reliable. Tumors with “benign” histologic features may metastasize, while bizarrely pleomorphic tumors may remain confned to the adrenal gland. In fact, cellular and nuclear pleomorphism, including the presence of giant cells, and mitotic fgures are often seen in benign pheochromocytomas, while cellular monotony is paradoxically associated with an aggressive behavior. Therefore, the defnitive diagnosis of malignancy in pheochromocytomas is based exclusively on the presence of metastases. Ans (a) Hamartoma (Ref: Robbins 8/e p262, 9/e p13) An overgrowth of a skin structure at a localized region is likely to be indigenous as well as benign; this is more likely to be a hamartoma. This results in stoppage of activation of Rb and cell cycle is arrested in G1/S phase. It can be as short as 2 hours in rapidly dividing cells like embryonic tissues or as long as 12 hours in some adult tissues. This enzyme is absent from most somatic cells, and hence they suffer progressive loss of telomeres.
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