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Biomedical subjects

B F Smith

Publications and source records attributed to B F Smith.

66 records · Page 4Linked to original sources
PubMedDate not supplied

Role of gallbladder mucin in pathophysiology of gallstones.

A critical step in the formation of cholesterol gallstones in nucleation (i.e., the formation of cholesterol monohydrate crystals from supersaturated bile). The rate of nucleation of cholesterol depends upon a critical balance between pronucleating and antinucleating factors in bile. Mucin, a high molecular weight glycoprotein secreted by the gallbladder and biliary duct epithelium, is a pronucleating agent in experimental and human gallstone disease. Gallbladder mucin shares with other epithelial mucins the ability to bind lipids and bile pigment. The hydrophobic binding sites in the polypeptide core of mucin may provide a favorable environment for nucleation of cholesterol monohydrate from supersaturated bile. In nearly all animal models of cholelithiasis, mucin hypersecretion is prominent. The stimulus for gallbladder mucin hypersecretion appears to be a component of lithogenic bile. Prostaglandins regulate mucin release in gallbladder epithelium in vitro and probably in vivo. In the cholesterol-fed prairie dog, blockage of mucin release with aspirin inhibits gallstone formation. These findings suggest that inhibition of mucin release may prevent cholesterol stone formation during high-risk periods or after dissolution therapy with bile salts.

Animals↗
PubMedDate not supplied

Utilization of umbilical cords to assess in utero exposure to persistent pesticides and polychlorinated biphenyls.

In support of a study to relate developmental and cognitive effects with prenatal exposure to selected environmental toxicants, we developed and applied an analytical method to determine the concentration of two persistent pesticides, hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (DDE), and 32 specific polychlorinated biphenyl (PCB) congeners in 316 umbilical cords taken in 1986-1987 from women of the Faroe Islands. The analytical method consisted of homogenization of the cords, partitioning, microsilica gel column chromatography for clean-up, and dual-column capillary gas chromatography (DB-5 and DB-1701) with electron capture detection. Several quality control parameters were followed to monitor the performance of the method. Important criteria used before reporting unknown data were the recovery of in vitro-spiked analytes from a bovine umbilical cord (BUC) and the percentage lipid obtained for a Certified Reference Material (CRM)-350 of mackerel oil (MO). Recoveries of analytes that had been spiked at two concentration ranges (0.26-0.95 ng/g whole weight; 0.35-2.42 ng/g whole weight) into bovine cords ranged from 38.5% to 158% and from 50.4% to 145%, respectively, with a median recovery of 77.7%. Measurement of the percentage lipid for CRM-350 ranged from 73.8% to 107% with a median lipid value of 96.0%. The most prevalent analytes detected (%) in unknown umbilical cords were HCB (100), DDE (100), Ballschmiter/Zell PCBs 153 (100), 138 (98), 180 (98), 170 (93), 118 (88), 187 (86), and 146 (83), with corresponding median concentrations (ng/g whole weight) of 0.17, 1.19, 0.38, 0.30, 0.17, 0.11, 0.12, 0.09, and 0.07, respectively. Total PCB--sum of all measurable PCB congeners--had a median concentration of 1.37 ng/g whole weight. The analytes, which were very low in lipid content were also quantified on a lipid-adjusted basis, which provided an analytical challenge in these umbilical cord samples. The gravimetrically measured lipids in the human specimens ranged from 0.01% to 1.43% (median of 0.18%). In the pooled BUCs, our lipid measurements varied from 0.05% to 0.33% with a median value of 0.13%. The utility of using the umbilical cord as a matrix to assess in utero exposure to persistent environmental pollutants, compared with the use of umbilical cord blood or mother's blood, is worthy of debate.

Adult↗
PubMedDate not supplied

Cerebrospinal fluid pleocytosis following hemorrhagic cerebral infarction.

A polymorphonuclear pleocytosis of the cerebrospinal fluid is an occasional occurrence following hemorrhagic cerebral infarction. Because the peak of this neutrophilic reaction occurs 3 to 4 days after the event it is usually missed and not widely appreciated. We have described an example of this response in an attempt to alert physicians to an important differential diagnostic consideration when faced with a neutrophilic CSF pleocytosis.

Cerebral Hemorrhage↗
PubMedDate not supplied

Stargardt's disease: the evolution of a diagnosis.

In Stargardt's disease, a gradual loss of vision may precede both the appearance of paracentral or peripheral retinal flecks as well as funduscopically obvious macular changes. This latency delayed a diagnosis of Stargardt's disease in a young girl who underwent neurologic testing for what eventually turned out to be a retinal problem. At one stage in evolution, when retinal flecks and only subtle changes in the maculae were present, a diagnosis of a pure form of fundus flavimaculatus was considered likely. When severe granularity and atrophy of the maculae later developed in the presence of the retinal flecks, a more appropriate diagnosis of Stargardt's disease was made. As the degenerative and atrophic changes in the maculae became more pronounced in early adulthood, the flavimacular retinal flecks had all but disappeared.

Child↗
PubMedDate not supplied

Factors associated with virulence of Mycoplasma synoviae.

Virulence mechanisms of six isolates of Mycoplasma synoviae (MS), previously classified as pathogenic (K1968), moderately pathogenic (WVU 1853, K1858, 92D8034, and F10-2AS), and mildly pathogenic (FMT) in chickens, were examined. The most virulent isolate, K1968, had been found to invade systematically and produce lesions following eye-drop inoculation. In the present study, all isolates were evaluated for presence of a possible cytadhesin and for functional attachment to host cells as indicated by hemagglutination and hemadsorption. Three representative isolates, K1968, 92D8034, and FMT, were evaluated for attachment and colonization in cultured chick tracheal rings and tendon cell monolayers by direct transmission electron microscopic examination and by quantitative polymerase chain reaction assay. Ciliostasis was compared in tracheal organ culture. Previously found differences in pathogenicity of these isolates for chickens could not be explained as differences in attachment and were only partially explained by differences in colonization. Pathogenicity of the most virulent isolate of MS was suspected to be multifactorial, involving attachment and colonization of the upper respiratory tract plus additional unidentified factors associated with systemic invasion and lesion production.

Animals↗