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By W. Lisk. Central Christian College of the Bible. 2018.

Myofibrils appear to be attached transversely at periodic adhesion sites discount 50 mg penegra with amex prostate cancer and diet. The protein titin spans the distance between Z-lines and the middles of the thick filaments 100mg penegra mastercard androgen hormone 2 ep1. The primary structural unit of tendon is the collagen molecule. Type I collagen consists of three polypeptide chains coiled together in a right-handed triple helix held together by hydrogen and covalent bonds. Fibers are further grouped into bundles called fascicles, which group together *German for “light. Elastic and reticular fibers are also found in tendon along with ground substance (a composition of glycosaminoglycans and tissue fluid). In an unstressed state, collagen fibers take on a sinusoidal appearance, referred to as a crimp pattern. These variations have functional consequences that led to the development of a variety of naming schemes to identify fibers with specific structural and functional properties (e. The T-system may be twice as extensive in one fiber compared to another. The first recorded scientific medical studies were undertaken by the Greeks around the 6th century B. Since then, advances in mathematics, chemistry, physics, and genetics have played a major role in identifying and characterizing muscle-tendon structure. Microscopy has been used extensively to study muscle. Lenses were first used to magnify objects around 1600 A. Microscopy has developed into a highly technical field utilizing a variety of illuminating approaches. Light microscopy was the first technique employed to study muscles and other biological tissues. Leeuwenhoek (1632–1723) was one of the first great biological microscopists. He manufactured hundreds of microscopes which he used to observe many biological tissues. Unfortunately, much of his expertise in tissue preparation and illumination was lost throughout the 18th and 19th centuries. Much of the work in light microscopy conducted then centered around correcting for artifacts and aberrations through matching glass, refractive media, and improving lens manufacturing. A variety of stains have been used to provide the contrast necessary to identify different organelles and gross struc- tures. Dark-ground, phase contrast, interference, and polarization microscopy identify regions of different refractive indices, but they accomplish this based on fundamentally different approaches. While most living, non-stained biological tissue is transparent when investigated with normal light microscopy, different regions of a cell have different refractive indices. In dark-ground microscopy, light is passed through the specimen at rather oblique angles so that the direct light beam passes to the side of the objective. Regions of high refractive index appear bright against a black background as they reflect the light to the eyepiece or viewing port. Phase contrast microscopy makes use of the relative phase differences in light passing through different regions of the tissue having different refractive indices. These phase differences are converted to changes in light intensity in the image plane. One beam passes through the specimen and the other beam passes around it. Light passing through high refractive index tissue is slowed down, phase shifted, relative to light passing around the tissue.

On the basis of this patient’s clinical presentation generic penegra 100mg with visa prostate cancer nutrition, the tissue transglutaminase antibody test is the one most likely to be helpful with the diagnosis buy cheap penegra 50mg online prostate cancer journal. A 44-year-old woman with a history of GSE is evaluated for refractory disease. Her disease was initially well controlled with a gluten-free diet. Over the past few months, she has had persistent diarrhea and malabsorption that has not responded to her usual diet. Findings on phys- ical examination are consistent with chronic malnutrition. An abdominal CT scan shows no masses or anatomic abnormalities that would account for her symptoms. An endoscopy is obtained, and small bowel biopsy shows villous atrophy and a layer of collagen underneath the enterocytes. Which of the following is the most likely explanation for this patient’s symptoms? Tropical sprue Key Concept/Objective: To know that collagenous sprue is a possible complication of gluten-sen- sitive enteropathy 18 BOARD REVIEW Collagenous sprue is a rare, devastating disease in which there is a layer of collagen under- neath the enterocytes of the small bowel. The origin of collagenous colitis is unknown, but it develops in approximately half the patients who have refractory celiac disease. The symptoms are severe and include obvious malabsorption. The diagnosis is made on the basis of the classic histologic picture of villous atrophy and subepithelial collagen deposi- tion. Therapy for collagenous sprue is uncertain; some patients respond to steroids. Poor adherence to gluten-exclusion diet is common; however, it would not explain the histo- logic changes seen in this patient. Small bowel lymphoma can be a complication of GSE; however, there is no evidence of this disorder on the imaging studies and biopsy. Tropical sprue is a malabsorptive disorder that appears in certain areas of the world. The diagnosis is based on the history of travel to endemic areas and a biopsy showing villous atrophy and inflammatory cells. A 60-year-old man is being evaluated in your clinic for diarrhea. He has undergone extensive evaluation over the past 2 months. A stool culture for bacterial organisms was negative, as were stool studies for the pres- ence of ova and parasites. Review of systems is positive for weight loss and occasional fever over the past 3 months. On physical examination, the patient’s temperature is 100. Skin hyperpigmentation and cervical lym- phadenopathy are noted. A small bowel biopsy shows villous atrophy and macrophages with sickleform particles. Which of the following therapies is indicated for this patient? Cholestyramine Key Concept/Objective: To be able to recognize Whipple disease The patient has clinical and laboratory findings consistent with the diagnosis of Whipple disease. This is a rare multisystem disease caused by infection with Tropheryma whippelii. Classically, the disease begins in a middle-aged man with a nondeforming arthritis that usually starts years before the onset of the intestinal symptoms. Arthralgias, diarrhea, abdominal pain, and weight loss are the cardinal manifestations of Whipple disease. Other complaints include fever, abdominal distention, lymphadenopathy, hyperpigmentation of the skin, and steatorrhea. The diagnosis rests on identifying the classic PAS-positive macrophages, which contain sickleform particles. The histologic lesion shows distended villi filled with the foamy, PAS-positive macrophages.