Biomedical subjects
Publications and source records attributed to J Fox.
Mosaicism with a normal cell line (N) and an unbalanced autosomal structural rearrangement (UASR) is rare. This report describes a case of a newborn female with a karyotype of 46,XX,der(4)t(4;15)(q35;q22)/46,XX. Molecular cytogenetic analysis confirmed the origin of the derivative chromosome 4. Here we discuss this case as well as other cases of mosaic karyotypes involving N/UASR.
Occupational exposure to bacterial or fungal antigens has been associated with hypersensivity pneumonitis (HP), an immunologically-mediated pulmonary disease. Between August 1995 and April 1996, 34 employees working in machining and assembly areas of an engine manufacturing plant were clinically diagnosed with HP. Of these, 20 employees met an epidemiologic case definition. In a case-control study, no exposure variables, including duration and intensity of metal working fluid (MWF) exposure, were statistically associated with an increased risk of disease. Neither cases nor controls demonstrated precipitin reactivity against unused samples of the seven MWF and two biocides used in the plant. HP cases had a significantly higher prevalence of positive precipitin reactions to used oil soluble and synthetic MWFs. Reactivity to used but not unused MWF suggests a biocontaminant, probably bacteria or fungi, is the causative antigen in the development of HP in this setting.
The increased recognition of both old and new enteric pathogens and their potential impact requires an improved understanding of pathogenesis and effective interventions. While the overwhelming mortality (> 3 million children per year) due to diarrheal diseases is well-recognized, the potential long-term impacts of enteric infections and early childhood diarrhea morbidity are just beginning to be appreciated. Furthermore, several enteric infections are now being recognized as causes of growth shortfalls with or without diarrhea; i.e., malnutrition may be one of the greatest yet of the "emerging infectious diseases." The increased appreciation of this extended impact calls for further quantification and improved understanding of the deranged physiology. In particular, persistent diarrheal illnesses exhibit common themes of blunted villi, disruption of intestinal barrier function and varying degrees of sub-mucosal inflammation for which lactulose/mannitol permeability and fecal lactoferrin provide respective quantification. Finally, such improved understanding will allow targeted interventions among those most vulnerable, which will enable further documentation of cost effectiveness and the potential for improved human development which is critical to reducing the widening disparity and population overgrowth which increasingly threaten our global security.
Two juvenile sibling male Muntjak deer (Muntiacus muntjak) with histories of depression, ataxia, circling and visual deficits were studied. Cerebrospinal fluid analyses revealed vacuolated macrophages that contained long parallel needle-like intracytoplasmic inclusions. Light microscopically, nerve cell bodies throughout the brain, ganglion cells within the retina and neurons in the myenteric plexuses were variably swollen and had pale granular to finely vacuolated eosinophilic cytoplasm. Neuronal cytoplasm stained specifically with sudan black and Luxolfast blue stains. Within the brain there were occasional axonal spheroids, foci of astrogliosis and scattered microglial cells with abundant pale foamy cytoplasm. Electron microscopy of the brain and retina revealed numerous neurons and ganglion cells, respectively, with multiple membrane-bound structures that contained compact electron-dense membranous whorls and fewer parallel membranous stacks. Thin layer chromatography of total lipid extracts of the cerebral cortex of both cases revealed massive accumulation of G(M2) ganglioside. Crude kidney extracts of the two affected deer were able to hydrolyze 4-methylumbelliferyl beta-GlcNAc, but not 4-methylumbelliferyl beta-GlcNAc-6-sulfate, indicating the defect of beta-hexosaminidase A. Cellogel electrophoresis of the kidney extracts also revealed the deficiency of beta-hexosaminidase A in the two deer. It is concluded that these two deer had the biochemical lesion identical to that of human type B G(M2) gangliosidosis (classical Tay-Sachs disease).
OBJECTIVE: Our aim was to determine the risk of cytologic abnormality on a screening Papanicolaou test for women >/=50 years old with and without a uterine cervix. STUDY DESIGN: The effect of hysterectomy on abnormal screening Papanicolaou test rates was determined in a cross-sectional analysis of 21,152 women aged >/=50 years who had screening Papanicolaou tests between January and August 1995. We then conducted a nested 1:1 case-control study of 172 case patients and 172 age-matched randomly selected control patients from the cohort. To control for potential confounders, conditional logistic regression was used to assess the effect of hysterectomy status on the risk of an abnormal Papanicolaou test. RESULTS: Compared with age-matched women with a uterine cervix, those who had a hysterectomy had a 10-fold lower risk of a screening Papanicolaou test abnormality (odds ratio 0.09, 95% confidence interval 0.02-0.24). The risk was further reduced among women taking estrogens (odds ratio 0.02, 95% confidence interval 0.004-0.14) compared with women not using estrogens (odds ratio 0.14, 95% confidence interval 0.04-0.56). CONCLUSIONS: The reduced risk of Papanicolaou test abnormalities among women aged >/=50 years who have had a hysterectomy should be considered when individual patients are being counseled, screening guidelines are being formulated, and health care resources are being allocated.
The Ca2+ receptor is the primary mechanism regulating the secretion of parathyroid hormone (PTH). Ligands that activate this receptor (calcimimetics) represent a novel means of lowering plasma levels of PTH. Two mechanistically distinct classes of calcimimetics that inhibit PTH secretion have been identified: type I calcimimetics are full agonists of the Ca2+ receptor and include Ca2+ and other polyvalent inorganic and organic cations; whereas type II calcimimetics, typified by phenylalkylamine compounds, behave like positive allosteric activators and increase, in a stereoselective manner, the sensitivity of the Ca2+ receptor to activation by extracellular Ca2+. The phenylalkylamine calcimimetics are orally active and decrease the plasma levels of PTH and Ca2+ in patients with primary hyperparathyroidism (HPT), a disease that so far has resisted pharmacological intervention. Such compounds are similarly safe and effective in reducing PTH levels and preventing parathyroid cell hyperplasia in rats with HPT secondary to chronic renal insufficiency and they lower plasma levels of PTH in dialysis patients with secondary HPT. Calcimimetic compounds may provide a novel therapy for treating both primary and secondary HPT.
We have developed CADMIUM, a novel approach for the design of systems to assist in the interpretation of medical images. CADMIUM uses symbolic reasoning to relate information obtained from image processing to the decisions radiologists take. The approach is based on a symbolic decision procedure which has already been used successfully in a variety of nonimaging clinical decision systems. In CADMIUM this decision procedure is extended with models of three generic image interpretation tasks: detection, measurement and classification of image features. The extended procedure is used to construct the lines of reasoning needed in each task and to control the acquisition of information by image processing. CADMIUM has been evaluated as an aid to the differential diagnosis of microcalcifications on mammographic images. Radiographers who had been trained to interpret images performed better when using the advice provided by the system.
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Structural chromosomal rearrangements occur commonly in the general population. Individuals that carry a balanced translocation are at risk of having unbalanced offspring; therefore, the frequency of translocations in couples with recurrent spontaneous abortions is higher than that in the general population. The constitutional t(11;22) translocation is the most common recurrent non-Robertsonian translocation in humans and may serve as a model to determine the mechanism that causes recurrent meiotic translocations. We previously localized the t(11;22) translocation breakpoint to a region on 22q11 within a low-copy repeat, termed "LCR22." To define the breakpoint on 11q23 and to ascertain whether this region shares homology with LCR22 sequences, we performed haplotype analysis on patients with der(22) syndrome. We found that the breakpoint on 11q23 occurred between two genetic markers, D11S1340 and APOC3-tetra, both being present within a single bacterial-artificial-chromosome clone. To determine whether the breakpoint occurred within the same region among a larger set of carriers, we performed FISH mapping studies. The breakpoints were all within the same clone, suggesting that this region may harbor sequences that are prone to breakage. We narrowed the breakpoint interval, in both derivative chromosomes from two unrelated carriers, to a 190-bp, AT-rich repeat, which indicates that this repeat may mediate recombination events on chromosome 11. Interestingly, the LCR22s harbor AT-rich repeats, suggesting that this sequence motif may mediate recombination events in nonhomologous chromosomes during meiosis.