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Biomedical subjects

S W Kennedy

Publications and source records attributed to S W Kennedy.

At least 37 records · Page 2Linked to original sources
PubMed1993

Improved method to extract and concentrate porphyrins from liver tissue for analysis by high-performance liquid chromatography.

A new method to extract and concentrate porphyrins from liver tissue for analysis by high-performance liquid chromatography is described. Porphyrins were extracted with acetonitrile-hydrochloric acid, concentrated on disposable octadecylsilyl columns, brought to dryness, and reconstituted in 1.2 M hydrochloric acid. Dried porphyrins were stable at -80 degrees C for at least three weeks, and porphyrins reconstituted in hydrochloric acid were stable for at least 20 h. Yields of uro-, heptacarboxyl-, hexacarboxyl-, pentacarboxyl- and coproporphyrin were > or = 90%. The method allows determination of porphyrin concentrations in small (10-100 mg) samples of liver tissue.

Acetonitriles↗
PubMed1993

Ethoxyresorufin-O-deethylase and porphyrin analysis in chicken embryo hepatocyte cultures with a fluorescence multiwell plate reader.

Rapid and sensitive methods for measuring ethoxyresorufin-O-deethylase (EROD) induction and total intracellular porphyrin accumulation in cultured chicken embryo hepatocytes exposed to polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are described. Cells were cultured in 48-well cell culture plates, and EROD assays were carried out directly within the wells. EROD activity and porphyrin concentrations were determined with a computer-operated fluorescence multiwell plate reader. Porphyrin and EROD assays could be carried out on the same plates or on separate plates. The assays allow one to obtain dose-response curves at rates that are approximately 100 times faster than conventional methods.

Animals↗
PubMed1992

Impact of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls on human and environmental health, with special emphasis on application of the toxic equivalency factor concept.

A scientific evaluation was made of the mechanisms of action of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls. Distinction is made between the aryl-hydrocarbon (Ah) receptor-mediated and non-Ah receptor-mediated toxic responses. Special attention is paid to the applicability of the toxic equivalency factor (TEF) concept.

Animals↗
PubMed1990

Dose-response relationships in hexachlorobenzene-induced porphyria.

The rate of development of hexachlorobenzene (HCB)-induced porphyria in female Wistar rats was determined using HCB dosage and porphyrin analysis protocols designed to determine factors which contribute to the delay commonly observed between initial exposure to HCB and the detection of porphyria. Measurements were made of HCB and porphyrin concentrations in the livers, kidneys, and spleens of female Wistar rats exposed continuously (up to 56 days) or for 1 day to HCB (at dietary concentrations of 1000 ppm and 100 ppm). The experiments showed that when a corn oil solution of HCB was added to the diet at a concentration of 1000 ppm, HCB accumulated rapidly in all organs, and the delay in appearance of elevated liver highly carboxylated porphyrins (HCPs) was at most 4 days (approximately 8-fold elevation of HCPs on day 4). One day of exposure to this diet was sufficient to cause elevated liver HCPs, thus showing that continuous exposure to HCB was not required to cause porphyria in this species. Solid HCB added directly to the diet (1000 ppm) resulted in less rapid HCB accumulation and less rapid development of porphyria. The experiments demonstrated that the appearance of a delay in HCB-induced porphyria in the Wistar rat is caused by the rate at which HCB is absorbed, and by using total hepatic porphyrins (rather than HCPs) as the indicator of the disorder. The experiments also showed that HCB-induced liver enlargement and neurotoxicity are not necessarily associated with the severity of porphyria.

Administration, Oral↗
PubMed1989

Separation of porphyrin isomers by high-performance liquid chromatography.

A high-speed reversed-phase high-performance liquid chromatographic method using an octadecylsilyl 3 cm long (3 microns particle size) column to separate the free acids of uroporphyrins I and III and coproporphyrins I and III from each other, and from the type I isomers of several other porphyrin carboxylic acids, is described. Separation of the porphyrins was achieved in less than 8 min, and injections were possible every 12 min. The detection limits of uroporphyrin, coproporphyrin, and mesoporphyrin were 75, 45, and 35 fmol (at a signal-to-noise ratio of 2), respectively. Application of the method to the determination of urinary and liver porphyrin patterns is shown.

Animals↗
PubMed1988

Immunocytochemical localization of glucocorticoid receptors in cells, cytoplasts, and nucleoplasts.

A monoclonal antibody has been used to assess the intracellular localization of the glucocorticoid receptor in rodent L-929 fibroblasts and GH3 pituitary tumor cells. Whole cells from both cell lines showed immunoreactivity in the cytoplasm and nucleus. However, when cytoplasts and nucleoplasts of these cells were examined, only L-cells showed strong antibody binding in both fractions; in contrast, GH3 cells exhibited nuclear staining and slight cytoplasmic staining. These results are discussed in terms of the current findings regarding the intracellular location of steroid hormone receptors.

Animals↗
PubMed1988

A high-speed liquid-chromatographic method for measuring urinary porphyrins.

We describe a rapid quantitative and qualitative "high-performance" liquid-chromatographic (HPLC) method for measuring porphyrins in urine. Direct injection of acidified, filtered urine onto a 3-micron (particle size) 3-cm-long reversed-phase column fully resolves uroporphyrin, hepta-, hexa-, and pentacarboxylic acid porphyrins, and coproporphyrin. Instrument response is linearly related to concentration over the range 25 to 300 nmol/L. The method provides data essential for the differential diagnosis of porphyric states, including porphyria variegata and porphyria cutanea tarda. This relatively inexpensive method requires a run time of only 8 min per sample, making it particularly suitable for routine use in the clinical chemistry laboratory.

Chromatography, High Pressure Liquid↗
PubMed1986

Tissue porphyrin pattern determination by high-speed high-performance liquid chromatography.

A rapid and sensitive method for the determination of porphyrin carboxylic acids in liver, kidney, and spleen by high-speed high-performance liquid chromatography is described. Porphyrins were extracted with recoveries greater than or equal to 98%, concentrated on disposable octadecylsilyl cartridges, and analyzed with a liquid chromatograph equipped with a 3 microns X 3 cm octadecylsilyl column and a fluorescence detector. Separation of di-, tetra-, penta-, hexa-, hepta-, and octacarboxylic acids was achieved within 5 min. The detection limits for uro, copro, and protoporphyrin were 20, 10, and 20 fmol, respectively.

Animals↗
PubMed1986

The delay in polyhalogenated aromatic hydrocarbon-induced porphyria: the effect of diet preparation.

Porphyria development in female Wistar rats has been followed by dosing the animals with hexachlorobenzene (HCB) either dissolved in corn oil or as a solid mixed with the diet. It was found that the corn oil preparation resulted in much faster uptake of HCB into the liver, and much faster accumulation of liver porphyrins. Diet preparation is thus shown to be a major factor in determining whether the development of porphyria is associated with the delay phenomenon. Evidence is also presented suggesting that the neurological symptoms of porphyria are not caused by high porphyrin levels.

Administration, Oral↗
PubMed1986

The delay in polyhalogenated aromatic hydrocarbon-induced porphyria: mechanistic reality or methodological artefact?

Hepatic porphyria was induced in female Wistar rats exposed to dietary hexachlorobenzene (HCB) for 56 days. The well-documented several-week delay before liver total porphyrins became elevated was observed using conventional methods. However, a newly developed high-performance liquid chromatography (HPLC) technique revealed a much earlier response. Highly carboxylated porphyrins were found to increase soon after exposure to the toxicant. The long delay observed by total porphyrin analysis is shown to be due to the relatively small contribution of highly carboxylated porphyrins to the total porphyrin pool. It is concluded that the concept of a latent period is largely a methodological artefact which has confused the search for a fundamental understanding of chemically induced porphyria.

Administration, Oral↗
PubMed1979

Fine structural studies of the rat vas deferens.

A fine structural study of the normal rat vas deferens was undertaken utilizing perfusion fixation. Morphological features not previously appreciated were revealed using this technique of fixation, and included the following. The rat vas deferens exhibited a gross morphological and microscopic differentiation along its length: A proximal segment was characterized by a thin muscular wall, an epithelium of low height (comparable to that of the cauda epididymidis) and a distended lumen typically filled with an accumulation of sperm; a distal segment exhibited a thick muscular wall, a convoluted mucosa, and a pseudostratified columnar epithelium with long stereocilia extending into the lumen. The transition from the morphology typical of the proximal segment to that of the distal segment was gradual and progressive, marked by an increase in the mass of the muscular wall and in the height and ultrastructural complexity of the epithelium. Clear or "foamy" cells, characteristic of the cauda epididymidis, were observed in the initial centimeter of the vas deferens. Also, a cell type designated as "mitochondrion-rich" was observed in the distal vas segment. The structure of the small mitochondria in such cells, however, did not conform to the description of mitochondria in similar cells found in the human (Hoffer, '76). Intraepithelial macrophages containing residual accumulations which often resembled spermatozoan remnants in advanced stages of dissolution were present in all segments of the rat vas deferens, confirming in this species a spermiophagic role for such cells.

Animals↗
PubMed1979

The active immunization of the cyclic ewe against an estrone protein conjugate.

Four mature, cyclic ewes were given injections (I.M.) of a conjugate of 1,3,5 (10)-estratrien-3-ol-6,17-dione, 6 carboxyoxime bovine serum albumin (immunized ewes) on day 3 after estrus, and at days 10, 20, 40, 58, 91 and 134 after this initial treatment. Six control ewes treated with carrier emulsion alone continued to cycle normally. Three of the immunized ewes failed to exhibit estrus, an associated preovulatory surge of LH and ovulation. One ewe showed 1 abnormally short estrous period and then became anestrus. Injection of an estrone-protein-conjugate at days 3 and 13 after estrus did not appear to interfere with the rate of structural luteolysis of the corpus luteum present, but plasma concentrations of progesterone reached abnormally high luteal phase levels and in 2 ewes failed, subsequently to decline to normal follicular phase levels. Estrone binding capacity rose as early as day 9 after first treatment, and concentrations of LH rose as early as day 14. Subsequently, plasma levels of LH, estrone and progesterone and antisera titer rose; the only significant cross reaction of the antisera was with estradiol 17beta (11.32 +/- 2.80%).

Journal Article↗