By H. Mitch. Zion Bible Institute.
The dopamine precursor levodopa order tadalis sx on line amex, which crosses the blood-brain barrier and elevates striatal dopam- inergic tone by increasing dopamine production in remaining nigral neurons buy tadalis sx 20 mg line, constitutes the most effective available symptomatic treatment (Cotzias et al order tadalis sx discount. Certain events occurring a decade later would provide greater insight into this mystery. The patient first presented in 1976 as a 23-yr-old male with 3 mo of progressive rigidity, tremor, bradykinesia, and masked facies. After dying from a subsequent drug overdose in 1978, autopsy of the brain revealed degeneration of the substantia nigra and at least one example of an eosino- philic, intracytoplasmic inclusion that resembled a classic Lewy body. Synthesis was initially based on a previ- ously published procedure (Ziering et al. His deterioration started several days after these procedural modifications were adopted. This interpretation was supported and extended by Langston and colleagues in 1983 (Langston et al. Over the course of the previous year, recreational abusers of meperidine analogs began presenting to California physicians with chronic parkinsonism. Of particular importance was the demonstration in 1986 that structures resem- bling Lewy bodies appeared within the substantia nigra of aged primates exposed to the toxin (Forno et al. Parker chose to assay platelets because they were procur- able from living patients, thus bypassing the pitfalls of working with autopsy tissue. Highly enriched mitochondrial fractions were prepared by centrifuging already concentrated mitochondria through a Percoll density gradient. Compared to that of control subjects, complex I activity was decreased by 55%, a statistically significant difference. This work was submitted in May 1989 to the Annals of Neurology after undergoing rejec- tion by Science, The New England Journal of Medicine, and Lancet. In 1990, Schapira and co-workers reported they were unable to detect complex I dysfunction in any part of the brain other than substantia nigra, where a 42% decrease was found relative to controls (Schapira et al. Similar results were again reported from this same laboratory 2 and 5 yr later (Mann et al. The assay of mitochondria suspended in the resultant homoge- nate is possible, and perhaps mandatory if only very limited amounts of tissue are available. Assay sensitivities are greatly increased by then preparing enriched mitochondrial fractions. To accomplish this, a relatively slow centrifugation step is performed to pellet out nuclei. Fast centrifugation of this supernatant then yields a mitochondrial pellet, which is resuspended in a buffer following its separation from the lipid-containing supernatant. This resuspension constitutes the crude mitochondrial fraction, the purity of which depends on the nature of the starting tissue. Crude mitochondrial fractions from lipid- rich tissues, including the brain, are generally less pure than those produced from other tissues, such as muscle. Because a large proportion of protein in crude mitochondrial fractions is mitochondrial, determination of protein concentration in the solution provides an appropriate reference for the amount of mitochondria in the assay. Citrate synthase activity is occasionally used as an additional surro- gate of mitochondrial concentration. The value of this step is dubious, because citrate synthase is a soluble enzyme that may preferentially leak from fragile mitochondria during preparation of the crude fraction. Assay sensitivity is further improved by subsequent gradient centrifuga- tion of the crude mitochondrial fraction, which allows for density separation of mitochondria from other similarly sized organelles. Enzyme activities are best referenced to total protein in these pure mitochondrial fractions. Finally, the specific environment within the reaction cuvet, such as the presence or absence of bovine serum albumin, influences activity determinations. In December, assays were performed with crude mitochondrial fractions, and a significant 16% complex I defect was detected (Krige et al. Even using crude mitochondrial fractions probably underestimates the magnitude of the defect in platelets, as pure 240 Swerdlow Fig. This is consistent with the hypothesis that complex I activity might decline with disease progression, as parkinsonism was less severe in the subjects of Haas et al. Interestingly, 3 yr later this group was unable to corroborate this result using lymphocyte crude mitochondrial preparations (Martin et al. Because such defects are potentially subtle and/or their clear demonstration is technically difficult, use of appro- priate methodology is absolutely essential. Negative studies using insuffi- ciently enriched mitochondrial fractions require cautious interpretation. The most scrutinized group of environmental toxins belong to the isoquinolone family, which in 1986 were shown to weakly inhibit complex I (Hirata et al. Other candidate environmental toxins include the `-carboline compounds, which also may occur in the food chain (Melchior and Collins, 246 Swerdlow 1982). Several `-carboline derivatives are weak inhibitors of complex I, although related `-carbolinium compounds provide more potent inhibi- tion (Hoppel et al. Experimental data inconsistent with this idea come from the study of Mytelineou and colleagues, who observed that fibroblast complex I dysfunction perpetuates even within a controlled environment (Mytelineou et al. Disease progression due to exogenous toxins suggests a need for serial re-exposure in all patients, an improbable scenario. Isoquinolone and `-carboline derivatives, for example, are physiologic byproducts of human metabolism (Melchior and Collins, 1982). Somewhat relevant to this issue are data from cybrid studies, which are described in a subsequent section of this chapter. Although it is highly polymorphic, its entire normal sequence is known (Anderson et al. Platelet mitochondria each contain only one copy, whereas brain mitochondria may carry more than five (Nass, 1969; Shmookler-Reis and Goldstein, 1983; Shuster et al. Cells containing hundreds of mitochondria therefore can possess thousands of copies of this genome. Wide ranges are possible, and deviant sequences may not necessarily confer phenotypic consequences if their percent composition is below a particular threshold. Replicative segregation may even account for mitochondrial genetic differences between identical twins. Most affected individuals in either case present sporadically or pseudosporadically (without a family history suggestive of autosomal dominant or recessive inheritance). The magnitude of the complex I defect in pure mitochondrial fractions derived from platelets is perhaps upward of 50% (Parker et al. Furthermore, it is often unclear whether or not detected mutations or polymorphic Cambridge sequence deviations are phenotypically relevant. Even under optimal circumstances, heteroplasmic species whose abundance is under 30% lie in a sequencing blind spot. This will likely remain the case until sequencing technologies advance to allow for the routine screening of low-abundance heteroplasmic mutations. Several groups explored methods for the experimental inducement of this condition (Wiseman and Attardi, 1978; Desjardins et al. Because the function of the pyrimidine pathway enzyme dihydroorotate dehydrogenase is normally coupled to complex I, uridine supplementation is also essential if ongoing nucleotide synthesis is to occur (Gregoire et al.
Gross and microscopic hair follicular analyses were primarily performed on white populations order tadalis sx 20 mg on-line. A basic understanding of the differences in the physical order discount tadalis sx, morphologic and histologic hair properties of the different ethnic groups is important in the assessment discount tadalis sx 20 mg on line, diagnosis, and management of patients with hair loss. In addition, a working knowledge of the microscopic anatomy of the normal hair follicle in both vertical and horizontal sections is vital in the understanding of hair follicle disease, leading to accurate interpretation of scalp hair biopsies. Microscopic cross-sectional views of an Asian hair shaft reveal a round or oval shape, dark pigmentation, and a wide diameter. The curvature of the black hair shaft is programmed from the follicular bulb (Fig. Hispanic hair has a structure comparable with white hair, in the authors experience. There are approximately 5 million hair follicles on the body and around 100,000 to 150,000 scalp hairs present on a normal scalp. The scalp possesses the greatest density of follicles rang- ing from 118 350 hair follicles/cm2 (6). Caucasians possess the highest density followed by blacks; Asians have the lowest density (7). Terminal hairs miniaturized to vel- lus hair proportions are described as vellus-like hairs such as seen in alopecia areata or andro- genetic alopecia. Terminal hairs are rooted in subcutaneous tissue or the deep dermis, while vellus hairs are rooted in the upper dermis. True vellus hairs have thin, external root sheaths and short stelae in the upper dermis. Vellus-like miniaturized hairs have thicker external root sheaths and long stelae extending into lower dermis or subcutaneous fat (6). Follicular stelae in the lower dermis indicate terminal, catagen, or telogen hairs or miniaturized vellus-like hairs (Figs. Specialized mesenchymal cells organize in a small con- densate directly beneath the basement membrane, stimulating the overlying epithelial stem cells to invaginate and penetrate into the dermis forming an epidermal peg (9,10). The epider- mal peg continues to grow downward enclosing the dermal condensate forming the dermal papilla. Cells of the follicular matrix terminally differentiate into inner root sheath and the hair shaft that exits from the surface of the skin. Fine lanugo hair develops in an advancing wave from the frontal to occipital scalp and it is shed by 36 weeks. A second coat of lanugo hair appears and it is shed in a synchronized wave pattern at 3 to 4 months of life. One vellus hair follicle is rooted in papillary dermis below a dilated infundibulum. One vellus-like hair follicle is rooted in upper dermis, but is attached to an underlying streamer (stela) extending down to reticular dermis, implying miniaturization of a terminal hair follicle. The third follicle shows a terminal hair in telogen at the level of insertion of the arrector pili muscle, the so-called bulge area where stem cells are found (elastin stain, 100x). The maximum number of scalp hair follicles during the human life span is present at birth. Thus hair follicle density is greatest in neonates and less- ens progressively during childhood and adolescence, due to expansion of cranium and scalp. The central vellus hair shaft has a diameter equal to the thickness of its investing inner root sheath. The diameter of the central hair shaft is slightly larger that the thickness of its inner root sheath. This suggests that it is a vellus-like hair, presumably a miniaturized terminal hair (hematoxylin and eosin stain, 400x). The variation in hair length is proportional to duration of the anagen depending on the body site. Studies on hair growth parameters indicated that scalp hair on blacks grows slower than on whites and Asians (14). At the end of anagen, the follicle enters the intermediate or catagen phase, which is marked by programmed cell death or apoptosis and lasts approximately 2 weeks. In catagen, the hair shaft and inner root sheath retreat upward while the outer root sheath undergoes cell death, and the hyaline membrane thickens and folds as it compacts upward. The lower follicle disappears leaving an angiobrotic strand or streamer (stela) indicating the former position of the anagen root. The ensuing telogen phase lasts an average of three months before a new anagen hair develops. In telogen, the resting club root is situated at the bulge level, where the arrector pili muscle inserts into the hair follicle (15). The telogen hair is shed during washing and grooming referred to as exogen phase. It is unclear whether this event requires molecular signaling or mechanical stimulus to dislodge the telogen club hair (16). Since there are approxi- mately 5% to 10% of scalp hairs in the resting phase, as many as 100 hairs per day may be lost. Local anes- thesia with lidocaine and epinephrine is suggested subject to patient hypersensitivity. The biopsy is angled in the direction of emerging hair fol- licles and should extend deep into subcutaneous tissue. Both halves are mounted in the block with cut surface downward, or one half is kept for additional studies such as immunouoresence techniques (Fig. The other 4-mm punch biopsy is bisected horizontally exactly parallel to the epidermis, 0. Sectioning progresses down toward the subcutaneous tis- sue in one half and up toward the epidermis in the other. Horizontal sections of scalp biopsies provide an accurate method for counting, typing, and sizing hair follicles (17). Horizontal versus Vertical Sections In the past, vertical sections of scalp biopsies have provided the traditional view of hair follicles. Most anatomical and histopathological features of hair follicles have been described using the vertical histologic sectioning technique. The concept of horizontal sectioning was introduced by Headington in 1984 and an increasing number of dermatopathologists are now interpreting horizontal sections (8). Horizontal sections generally demonstrate 20 to 30 follicles compared to the traditional four to six hair follicles seen in vertical sections (Figs. The horizontal sectioning technique readily allows quantication and assessment of the follicle density, follicle diameter, and the proportion of follicles in various stages of the hair cycle, i. This technique also demonstrates normal ethnic variation in follicle size and density (7). Both halves of the specimens are mounted on a block with cut surfaces facing downward.
Definition Cardiomyopathy is a disease of the myocardium resulting in thickening of the myocardial fibers or fibrosis purchase tadalis sx 20 mg on-line. Hypertrophic cardiomyopathy is characterized by thickening of the muscular walls of the ventricles best purchase tadalis sx, typically involving the ven- tricular septum buy discount tadalis sx online. Dilated cardiomyopathy may also cause hypertrophy of the ventricu- lar walls, however due to severe dilation of the ventricular chambers, they appear thin and stretched. Torchen Incidence Cardiomyopathy is a chronic and variably progressive disease of the heart muscle that can present in various forms and in severe cases can lead to heart failure and sudden death. However, it has to be noted that many asymptomatic and undiagnosed cases are unaccounted for in this survey. Infants less than a year old are ten times more likely to develop cardiomyopathy compared to children aged 2 18 years. Pathology Hypertrophic cardiomyopathy is characterized by abnormal growth and arrange- ment of muscle fibers, termed muscle disarray. The process starts in the ventricles and in severe cases can involve the wall of the atria. Cardiomyopathy could also be secondary to a more generalized metabolic, mitochondrial, or multi- system disorder. In hypertrophic cardiomyopathy most commonly the left ventricle is the more affected chamber with the septum showing the most growth. The thickening can sometimes be symmetric or concentric involving the entire left ventricular wall or localized to the apex in rare cases. After starting as a patchy lesion, the process can gradually spread to involve the entire right ventricle and then to the left ventricle. Hypertrophic cardiomyopathy causes abnormal relaxation of the heart during diastole and secondary obstruction to venous return. In the terminal stages of this disease, the heart resembles those seen in a dilated cardiomyopathy. In restrictive cardiomyopathy there is normal systolic function but abnormal relaxation. Clinical Manifestations Cardiomyopathy is not gender, race, geography or age specific. About 50 60% of children with hypertrophic cardiomyopathy and 20 30% with dilated cardiomyo- pathy have a family history. Symptoms of hypertrophic cardiomyopathy could first manifest with the spurt of growth during puberty. Other presenting features may include a murmur, arrhythmias, chest pain and syncope. There also may be an association with a malformation syndrome with dysmorphic features specific to the syndrome, such as short stature and webbed neck seen in Noonan s syndrome. Diagnostic Testing Any suspicion of cardiomyopathy should prompt a consult to the pediatric cardiologist. Echocardiogram is the most widely used and most informative noninvasive test for diagnosing cardiomyopathy (Fig. With echocardio- gram, the practitioner cannot only specify the type of cardiomyopathy but also determine the degree of dysfunction of the heart muscle. Measurements of the pressures in the ventricles and the great vessels like the pulmonary artery may also be performed. In addition a chest X-ray, electrocardiogram and a 24 72 h Holter monitor are necessary for evaluation. In some cases there may be need for more invasive tests like radionuclide ventriculogram or cardiac catheterization. This helps in evaluating for possible infections of the heart and certain metabolic diseases. Certain biochemical, genetic and enzyme deficiency tests are needed before starting the most appropriate medical therapy. It is especially important to get a metabolic screening in children with cardiomyopathy under 4 years of age. This may require additional blood, urine and tissue testing in consultation with special- ists such as geneticists or neurologists. Improving the contractility by using dopamine and dobutamine in critically ill patients and digoxin orally as maintenance therapy. Control of symptoms related to obstruction with calcium channel blockers or beta blockers like verapamil and propranolol. Prevention of arrhythmias and sudden death with antiarrhythmics like amio- darone or disopyramide. Patients with associated metabolic disorders may need careful dietary monitoring of fats, avoidance of fasting and possible daily carnitine orally. Dual chamber pacing has been shown to decrease outflow obstruction in hypertro- phic cardiomyopathy. An automatic internal cardioverter defibrillator is recom- mended in cases of severe life threatening arrhythmias, syncope, or history of resuscitation from a cardiac arrest. Myectomy is the surgical removal of part of the thickened septal muscle that blocks the blood flow in hypertrophic cardiomyopathy. Even though it may control symptoms of heart failure secondary to obstruction, studies have not shown that this procedure prevents sudden death from arrhythmias or stops progression of the disease. Heart transplantation is the last resort when patients reach the end stage of the disease. About 20% of symptomatic infants with cardiomyopathy require a cardiac transplant within the first year of life. In addition, children greater than 50 kg are eligible for support by a device called Left Ventricular Assist System for about 3 12 months. Those with a family history of cardiomyopathy and no symptoms may continue screening every 5 years thereafter. If a specific genetic diagnosis is made all siblings should be genetically tested to assess their risk. Torchen Prognosis The overall prognosis depends on the type of cardiomyopathy and the age at first diagnosis. Up to 40% of children with a diagnosis of cardiomyopathy fail medical treatment within first year of diagnosis. Mortality and heart transplant rates are much higher in children with cardiomyopathy as compared to adults. For those children who acquire cardiomyopathy secondary to a viral infection 33% recover, 33% stabi- lize and 33% experience progression of their disease. Current 5-year survival for children diagnosed with hypertrophic cardiomyopathy is 85 95%, while it is 40 50% with dilated cardiomyopathy. Sudden cardiac deaths accounts for 50% of deaths in hypertrophic cardiomyopathy and 28% in restrictive cardiomyopathy. Case Scenarios Case 1 History: A 6-month-old girl is suspected of having reactive airway disease. For the past 2 months she has had several visits to the primary care physician for manage- ment of shortness of breath and wheezing. Inhaled bronchodilators were prescribed in the past with no significant improvement.