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Biomedical subjects

R Perry

Publications and source records attributed to R Perry.

At least 55 records · Page 3Linked to original sources
PubMed1987

Nonfimbrial, mannose-resistant adhesins from uropathogenic Escherichia coli O83:K1:H4 and O14:K?:H11.

Nonfimbrial, mannose-resistant hemagglutinins (nonfimbrial adhesions [NFA] NFA-1 and NFA-2) were extracted from two agar-grown urinary isolates of Escherichia coli strains 827 (O83:K1:H4) and 54 (O14:K?:H11). The proteins were purified to homogeneity by ammonium sulfate precipitation and column chromatography. Nonfimbrial adhesins are soluble proteins, which tend to form aggregates of molecular weight above 10(6). NFA-1 and NFA-2 consist of subunits of 21,000 and 19,000 molecular weight, respectively. Both hemagglutinins caused hemagglutination of human erythrocytes and bound to human kidney cell monolayers. The binding of bacteria and hemagglutinins was assessed by using suitable antisera as detectors in an enzyme-linked immunosorbent assay. NFA-1 and NFA-2 inhibited the adherence of their respective strains to human kidney cells in a linear dose response. NFA-2 also inhibited heterologous strain adherence, but NFA-1 did not. Hemabsorption of bacterial suspension with erythrocytes at 4 degrees C, followed by differential centrifugation, enabled us to obtain a bacterial suspension lacking nonfimbrial adhesins in the supernatant and an adhesin-enriched bacterial suspension that was eluted from erythrocytes at 40 degrees C. Bacteria eluted from erythrocytes exhibited a higher adherence capacity than unfractionated cells. Bacteria of the fraction lacking adhesins did not adhere to human kidney cells. Electron microscope examinations showed the presence of an extracellular capsule-like layer in adhering E. coli 827, but not in nonadhering bacteria. E. coli 54 did not express the adhesin as a capsule. We conclude that E. coli 827 and 54 produce extracellular adhesins consisting of soluble proteins which are differently expressed and antigenically distinct. The adhesins seem to share a common receptor and mediate the adherence of two uropathogenic E. coli strains to epithelial cells.

Adhesins, Escherichia coli↗
PubMed1986

Plasma growth hormone response to insulin-induced hypoglycemia in infantile autism: a pilot study.

Plasma growth hormone responses to insulin-induced hypoglycemia were examined in eight preschool-age autistic children. Six of these children were examined on two separate occasions: during the period of baseline evaluation and after 4 weeks of daily haloperidol administration. On at least one occasion, half of this small sample exhibited persistent elevation of growth hormone levels, with a failure to return to baseline values over the course of a 135-minute period postinsulin infusion. These data are consistent with the occurrence of hypothalamic dysfunction in subgroups of autistic children. Short-term administration of haloperidol did not diminish the ability of the pituitary to secrete growth hormone in response to insulin-induced hypoglycemia.

Autistic Disorder↗
PubMed1986

Effect of salinity gradients and heterotrophic microbial activity on biodegradation of nitrilotriacetic acid in laboratory simulations of the estuarine environment.

The biodegradation of nitrilotriacetic acid (NTA), a synthetic replacement detergent builder, in the estuarine environment was examined by using a laboratory estuarine simulation. Two interdependent microcosms were used; each of five vessels was equilibrated with a saline gradient between 1.30 and 17.17%, with the final vessel subsequently being increased to a maximum salinity of 31.6%. Each microcosm was seeded simultaneously with heterotrophic bacteria from both fresh and saline sources. Viable counts demonstrated the ability of each microcosm to sustain a mixed heterotrophic bacterial community throughout the range of salinities for 183 days after a stabilization period. Isolation studies demonstrated that both systems contained four bacterial species, representatives of the genera Vibrio and Flavobacterium and members of the coryneform group and the family Enterobacteriaceae. Total bacterial numbers and species diversity decreased with increased salinity. NTA was administered at low and high concentrations, one concentration to each microcosm, initially with the least amount of saline. Removal of both concentrations of NTA occurred and was attributed to biodegradation after a period of bacterial acclimatization. Subsequent dosing of NTA to vessels of higher salinity demonstrated that biodegradation was incomplete at observed mean salinities of greater than 9.18% at low influent NTA concentrations and greater than 5.08% at high influent NTA concentrations. Therefore, acclimatization was dose dependent. It was concluded that NTA acclimatization at the higher salinities ceased because of salinity stress-induced failure of NTA catabolism and not the disappearance of a particular bacterial species.

Acetates↗
PubMed1985

Quantitative assays of pharmacologic aerosols used in studying asthma.

To more nearly accurately quantitate the dose of pharmacologic agents delivered to human and animal airways via aerosols, we have developed a monodisperse aerosol containing either methacholine or histamine that permits a light scattering device (tyndallometry) to measure accurately the quantity of inspired and expired particles. These aerosols (described in previous studies) are simultaneously tagged with a radioactive label (technetium 99m) to permit the use of external gamma camera imaging. Present work focuses on the development of assay techniques to measure the quantity of methacholine delivered in these aerosols. The lack of specific radioimmune or radioenzyme assays coupled with the cross-reaction of organic contaminants with conventional chemical reagents for measuring methacholine required the development of separative techniques to isolate the methacholine from the organic aerosol contaminants. With aqueous extraction and column separation we have been able to completely isolate the methacholine from these contaminants. This allows the application of standard spectrophotometric assays for methacholine to quantitate the methacholine in the resulting solution. These separative techniques will permit the use of these aerosols in quantitative studies of airway reactivity.

Aerosols↗
PubMed1979

Nursing and 2001.

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Forecasting↗