Re: "Baldness and ischemic heart disease in a national sample of men".
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Adult↗
Biomedical subjects
K Sheikh
Publications and source records attributed to K Sheikh.
Motor nerve terminal degeneration provides a potential mechanism for rapid recovery in acute motor axonal neuropathy after Campylobacter infection.
We investigated the possible mechanisms of paralysis and recovery in a patient with the acute motor axonal neuropathy (AMAN) pattern of the Guillain-Barré syndrome. The AMAN pattern of GBS is characterized clinically by acute paralysis without sensory involvement and electrodiagnostically by low compound motor action potential amplitudes, suggesting axonal damage, without evidence of demyelination. Many AMAN patients have serologic or culture evidence of recent Campylobacter jejuni infection. Pathologically, the most severe cases are characterized by wallerian-like degeneration of motor axons affecting the ventral roots as well as peripheral nerves, but some fatal cases have only minor changes in the roots and peripheral nerves, and some paralyzed patients with the characteristic electrodiagnostic findings of AMAN recover rapidly. The mechanism of paralysis and recovery in such cases has been uncertain. A 64-year-old woman with culture-proven Campylobacter upsaliensis diarrhea developed typical features of AMAN. She improved quickly following plasmapheresis. Her serum contained IgG anti-GM1 antibodies. The lipopolysaccharide of the organism bound peanut agglutinin. This binding was blocked by cholera toxin, suggesting that the organism contained the Gal(beta1-3)GalNAc epitope of GM1 in its lipopolysaccharide. Motor-point biopsy showed denervated neuromuscular junctions and reduced fiber numbers in intramuscular nerves. In contrast, the sural nerve biopsy was normal and skin biopsy showed normal dermal and epidermal innervation. In AMAN the paralysis may reflect degeneration of motor nerve terminals and intramuscular axons. In addition, the anti-GM1 antibodies, which can bind at nodes of Ranvier, might produce failure of conduction. These processes are potentially reversible and likely to underlie the capacity for rapid recovery that characterizes some cases of AMAN.
Biopsy↗
What do we learn from disciplined practice learning?
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Coronary Artery Bypass↗
Acute motor axonal neuropathy: an antibody-mediated attack on axolemma.
The acute motor axonal neuropathy (AMAN) form of the Guillain-Barre syndrome is a paralytic disorder of abrupt onset characterized pathologically by motor nerve fiber degeneration of variable severity and by sparing of sensory fibers. There is little demyelination or lymphocytic inflammation. Most cases have antecedent infection with Campylobacter jejuni and many have antibodies directed toward GM1 ganglioside-like epitopes, but the mechanism of nerve-fiber injury has not been defined. In 7 fatal cases of AMAN, immunocytochemistry demonstrated the presence of IgG and the complement activation product C3d bound to the axolemma of motor fibers. The most frequently involved site was the nodal axolemma, but in more severe cases IgG and C3d were found within the periaxonal space of the myelinated internodes, bound to the outer surface of the motor axon. These results suggest that AMAN is a novel disorder caused by an antibody- and complement-mediated attack on the axolemma of motor fibers.
Acute Disease↗
A prospective study of suramin-induced peripheral neuropathy.
Suramin is an investigational drug that has shown therapeutic activity in hormone-refractory metastatic prostate cancer in Phase I/II trials. Dose-limiting neurotoxicity remains the most serious complication of suramin treatment. We performed a prospective study to define the incidence, severity, characteristics, and dose relationships of suramin-induced peripheral neuropathy. Twenty-two patients who received suramin in a Phase-I trial underwent baseline and serial follow-up neurological evaluations consisting of history, examination, nerve conduction studies and quantitative sensory testing (QST). Suramin was administered intravenously in escalating dosages by using a 5-day schedule (repeated monthly), with the dose, determined by a population pharmacokinetic model, to accomplish 30-min post-infusion concentrations of 300 micrograms ml-1 (cohort I), 350 micrograms m-1 (cohort II) and 400 micrograms ml-1 (cohort III). Twelve patients developed a mild, axonal, length-dependent, sensory-motor poly-neuropathy. Three other patients developed a subacutely progressive, functionally disabling, demyelinating neuropathy; sural nerve biopsy in two patients showed lymphocytic inflammation. These three patients improved after drug discontinuation and plasmapheresis. Although there was no apparent correlation between the cumulative dose and the severity of the neuropathy, no patient from cohort I, but 88% of patients from cohorts II and III, developed neuropathy. We conclude that when suramin is used at peak concentrations of > or = 350 micrograms ml-1 its administration is associated with two patterns of neuropathy, a distal axonal neuropathy and an inflammatory demyelinating neuropathy that is partially reversible. Neurological monitoring for development of neuropathy will improve the safety of suramin use in future clinical studies.
Aged↗
Real-time, three-dimensional echocardiography: feasibility and initial use.
The purpose of this article is to review new approaches to three-dimensional acquisition and presentation of echocardiographic data. New three-dimensional phased-array devices hold great promise for the development and application of new descriptors for left ventricular performance, myocardial perfusion, and other important indices of cardiac function.
Echocardiography↗
Modulation of neonatal rat myeloid kinetics resulting in peripheral neutrophilia by single pulse administration of Rh granulocyte-macrophage colony-stimulating factor and Rh granulocyte colony-stimulating factor.
Rh granulocyte-macrophage (GM) colony-stimulating factor (CSF) and rh granulocyte (G) CSF have been demonstrated to induce proliferation and maturation of myeloid stem cells and release of mature polymorphonucleocytes (PMNs) from human and animal adult bone marrows. Unfortunately, reduced bone marrow progenitor cells, neutrophil storage pool (NSP) depletion and peripheral neutropenia are characteristic of human and animal newborn bone marrows. We investigated the effect of administering intraperitoneal rhGM-CSF and rhG-CSF to Sprague-Dawley newborn rats (less than 36 h). Newborn rats treated with intraperitoneal CSF (3.0 micrograms/kg) demonstrated significant leukocytosis at 6 and 24 h: rhGM-CSF vs. control, WBC (10(3)/mm3), at 6 h, 8.0 +/- 0.5 vs 4.3 +/- 0.9 (p less than or equal to 0.003), and at 24 h, 7.7 +/- 1.7 vs. 3.8 +/- 0.2 (p less than or equal to 0.008); rhG-CSF vs. control WBC (10(3)/mm3) at 6 h, 6.6 +/- 1.2 vs 4.3 +/- 0.1 (p less than or equal to 0.03), and at 24 h, 8.1 +/- 0.2 vs. 3.75 +/- 0.2 (p less than or equal to 0.003). The absolute neutrophil count was also significantly elevated at 6 h following intraperitoneal CSF (3.0 micrograms/kg): RhGM-CSF vs. control 1,827 +/- 25 vs. 379 +/- 10 (p less than or equal to 0.001); rhG-CSF vs. control, 1,698 +/- 40 vs. 371 +/- 10.1 (p less than or equal to 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Mortality of workers at acetylene production plants.
To reduce the risk of explosion oxyacetylene cylinders are filled with a spongy mass, acetone is added to saturate the mass, and acetylene is pumped into the cylinder. The first cylinders manufactured before 1936 used a kapok filling topped off with about 16 oz of crocidolite asbestos, with a metal gauze thimble inserted to reduce risk of flash back. Cylinders must be examined annually. The use of crocidolite ceased in 1972 and other fillings have been adopted since 1970; kapok cylinders now constitute less than 5% of the total stock. To assess possible hazards, a mortality study of workers first employed between 1935 and 1975 and followed up to December 1984 was undertaken. Simulation tests showed low concentrations of asbestos in the air even in the earliest period. The population studied consisted of 370 workers at the Bilston plant in the West Midlands, 611 at the 14 other plants in England and Wales, and 120 in Scotland. No deaths occurred from mesothelial tumours but there was an excess of deaths from cancer, particularly lung cancer, cancer of the stomach, and cancer of the pancreas, the latter accounting for eight deaths. Risks appeared to be concentrated at the Bilston plant. The importance of these findings is discussed.
Acetylene↗
Chemically modified collagen: a natural biomaterial for tissue replacement.
Glutaraldehyde crosslinking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation. Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable crosslinks. Tissues crosslinked with glutaraldehyde retain many of the viscoelastic properties of the native collagen fibrillar network which render them suitable for bioprostheses. Implants of collagenous materials crosslinked with glutaraldehyde are subject long-term to calcification, biodegradation, and low-grade immune reactions. We have attempted to overcome these problems by enhancing crosslinking through bridging of activated carboxyl groups with diamines and using glutaraldehyde to crosslink the epsilon-NH2 groups in collagen and the unreacted amines introduced by aliphatic diamines. This crosslinking reduces tissue degradation and nearly eliminates humoral antibody induction. Covalent binding of diphosphonates, specifically 3-amino-1-hydroxypropane-1, 1-diphosphonic acid (3-APD), and chondroitin sulfate to collagen or to the crosslink-enhanced collagen network reduces its potential for calcification. Platelet aggregation is also reduced by glutaraldehyde crosslinking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen. The cytotoxicity of residual glutaraldehyde--leaching through the interstices of the collagen fibrils or the tissue matrix--and of reactive aldehydes associated with the bound polymeric glutaraldehyde can be minimized by neutralization and thorough rinsing after crosslinking and storage in a nontoxic bacteriostatic solution.
Adenosine Diphosphate↗
Occupational injury, chronic low back pain and return to work.
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Adolescent↗
Choice of control population in studies of adverse reproductive effects of occupational exposures and its effect on risk estimates.
Cohort studies of adverse reproductive effects of occupational exposures that compare the outcome of exposed pregnancies with non-exposed pregnancies among the same group of mothers (internal controls) and among a different group of mothers (external controls) have been reviewed. Confounding of the hypothesised associations by parental characteristics, the outcome of previous pregnancies, and other exposures is not adequately assessed in these studies. The risk of an adverse outcome appears to be consistently higher among the external control group of pregnancies than among the internal controls. If the differences between the two control groups are real, comparisons based on external controls underestimate the relative or attributable risk. Alternative explanation for this phenomenon are discussed. A likely explanation is a misclassification of exposure or a high prevalence of risk factors other than the exposure of interest among the external controls. Non-exposed pregnancies among exposed mothers may be used for comparison in preference to pregnancies among non-exposed mothers.
Abortion, Spontaneous↗
Predicting risk among non-respondents in prospective studies.
Potential non-response bias was investigated in a follow-up study of 2,011 chronically disabled patients. 82.5% and 73.3% of the study subjects responded to self-administered mail questionnaires respectively at 6-month and 1-year follow-up. Information on employment status, the outcome of interest, of approximately 90% of the non-respondents was obtained from indirect sources. Employment rate was lower among the non-respondents than the respondents. Non-response was associated with age, social class, previous employment record, and the type of disability; but none of these characteristics were associated with the outcome. Out of the five known independent risk factors for unemployment, only one (incompletion of rehabilitation course) was associated with non-response. The employment rate among the respondents was also assessed according to the delay in response, that is the number of reminders sent to achieve response. The outcome among the late respondents was similar to that among the non-respondents. These data suggest that risk estimates may be biased even when the response rate is greater than 80%, the prevalence of risk factors among non-respondents may not indicate the presence or the degree of non-response bias, but reliable estimates can be obtained from extrapolations of the rates among the respondents according to the delay in response.
Age Factors↗
Langerhans cells in verruciform xanthomas: an immunoperoxidase study of 10 oral cases.
Ten oral verruciform xanthomas were studied using an immunoperoxidase stain for S-100 protein. All cases exhibited positively stained dendritic cells among the mononuclear inflammatory cell infiltrate at the base of the lesions and to a lesser extent among the "foam cells". The foam cells were, however, negative for S-100 staining. We suggest that, based on these findings, verruciform xanthomas belong to a new category of "non-X histiocytoses" in which the presence of Langerhans cells suggests an immunologic pathogenesis.
Foam Cells↗
Union-based surveillance of occupational hazards.
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Environmental Exposure↗
Disability scales: assessment of reliability.
Modified or newly developed disability scales have to be assessed for their validity in terms of an appropriate standard and for reproducibility--inter- and intraobserver variability and intrasubject variability. For ordinal scales with more than two points or categories, correlation or regression coefficients are appropriate estimates of validity. An assessment of the sensitivity and specificity of such a scale is not feasible. Indices of proportion agreement or correlation analysis are frequently used to assess the reproducibility of disability scales. These procedures do not, however, correct for chance-expected agreement between two or more sets of observations. In a study of a 31-point ADL (activities of daily living) index used to measure the level of disability in patients with chronic diseases, scores independently rated by two observers were strongly correlated (r = 0.962), yet the two sets of observations were significantly different. An estimate of kappa statistic, that corrects for chance agreement, showed that there was in fact a poor (36.3%) overall agreement between the observers. It is concluded that the correlation coefficient often overestimates the degree of true agreement, may conceal significant disagreements, and may give misleading information about reproducibility. The kappa statistic should always be used in the assessments of reproducibility of disability scales. Agreement between more than two sets of observations can also be assessed by estimating kappa.
Activities of Daily Living↗
Return to work following limb injuries.
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Adolescent↗
Employment rehabilitation: outcome and prediction.
Several factors have been shown to influence return to work after chronic disability, but little is known about their independent effect. There is also some disagreement about what constitutes successful resettlement in work. To establish the predictors of an early return to stable employment, 1,565 rehabilitees discharged from two employment rehabilitation centers in England were followed for at least 1 year. Nineteen entry characteristics and six outcome measures were analyzed by the canonical correlation method. Results in the two groups of rehabilitees were fairly similar. Three variables contributed most to the outcome measure: getting a job, delay in starting work, and employment status at the time of follow-up. Factors associated with a successful outcome were motivation, a low level of physical disability, short duration of unemployment before rehabilitation, completion of rehabilitation course, and a low level of general unemployment in the home area of the rehabilitee.
Adolescent↗
Adverse health effects of ethylene oxide and occupational exposure limits.
The proposed revision of the US standard for occupational exposure to ethylene oxide has recently been topical and controversial. Most of the recent experimental and epidemiological evidence of health effects, which provoked lowering the permissible exposure limit, appears to be unreliable and insufficient for risk assessment.
Animals↗