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Biomedical subjects

M A Walker

Publications and source records attributed to M A Walker.

At least 91 records · Page 5Linked to original sources
PubMed1985

Osmosin and ileal ulceration: a case report.

A 78-year-old woman presented with an acute abdomen and was found to have a perforation of her terminal ileum. She did not survive the post-operative period and at necropsy was found to have numerous ulcers of the ileum. In the ulcerated areas there was a transmural chronic inflammatory infiltrate, but no evidence of granulomata. We believe that this ulceration was caused by ingestion of Osmosin tablets containing indomethacin and suggest a possible pathogenesis.

Aged↗
PubMed1984

Lymphatic endothelial and smooth-muscle cells in tissue culture.

Endothelial and smooth-muscle cells from bovine mesenteric lymphatic vessels have been collected and cultured in vitro. The endothelial cells grew as a monolayer exhibiting a "cobblestone" appearance with individual cells tending to be more flattened at confluence than their blood vascular counterparts. Approximately 30% of these cells expressed Factor VIII antigen compared with bovine mesenteric artery or human umbilical-vein endothelium in which the majority of cells were positive. The lymphatic smooth-muscle cells exhibited focal areas of multilayering and were Factor VIII negative. The availability of lymphatic endothelial and smooth-muscle cells in culture will provide a new tool for the investigation of the biological properties of the lymphatic vessels and their role in homeostasis.

Animals↗
PubMed1984

The appendix stump: should it be invaginated?

In a prospective trial of 103 patients undergoing appendicectomy, one group of patients had the appendix stump treated by ligation alone and the other group underwent ligation and invagination. The two groups of patients were similar with respect to age, sex, incision and degree of inflammation of the appendix. Perforated appendices were excluded and in neither group were drains used or antibiotics given. No significant difference between the two methods of treatment of the appendix stump was noted, either with respect to wound infection or postoperative stay in hospital.

Adolescent↗
PubMed1983

Effect of luteinizing hormone on progesterone production by the follicular granulosa in the ovarian hierarchy of the domestic fowl (Gallus domesticus).

A LH function test was used to assess the effect of a previously administered dose of ovine LH on the granulosa from the four largest preovulatory follicles, F1-F4, of laying hens. At intervals of 1, 3, and 6 hr after intravenous ovine LH (40 micrograms; a dose previously shown to cause atresia) or carrier solution (1% bovine serum albumin solution, BSA), a second dose of LH or carrier was injected. The progesterone contained in the dissected granulosa of the F1-F4 follicles 45 min after the second injection was measured by radioimmunoassay. With birds injected with BSA, the mean basal levels ranged from 17 to 59 ng progesterone per granulosa, irrespective of the follicular type. In short-term experiments, i.e., 45 min after LH, the mean progesterone contents of F1 (262 ng) and F2 (137 ng) were significantly higher than their controls, whereas those of F3 (59 ng) and F4 (21 ng) did not change. The response per cell was greater in the F1 granulosa than in that of F2-F4; other evidence is presented to support a hypothesis that the F1 granulosa contains a larger LH receptor population. The effect of LH over a longer period (6 hr) was shown by a decline in the steroidogenic response of the F1 granulosa only. The kinetics of this decline (estimated t1/2 13.7 hr) resembled that previously reported for adenylate cyclase activity in granulosa cells from postovulatory follicles (POF) (t1/2 about 14.4 hr).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

"Aging" pigments in term human placenta.

First-, second-, and third-trimester placentas were examined with fluorescent microscopy for the presence of lipofuscin pigments. Prior to 32 weeks' gestation these were not seen, but they were routinely found in the trophoblast of the term placenta. These pigments may or may not represent "aging" of the placenta.

Female↗
PubMed1980

Biosynthesis of carotenoids derived from neurosporene in Rhodopseudomonas capsulata.

We have characterized the carotenoids accumulated by a series of mutants of Rhodopseudomonas capsulata as part of a study of the synthesis, structure, and function of the photosynthetic membranes of this bacterium. The carotenoids in this study were identified by visible and mass spectroscopy, chromatography, derivatization, and chemical analyses. We have located a new genetic region, crtF, necessary for the O-methylation of the carotenoids. Mutants with a lesion in crtF accumulate demethylspheroidene as their major carotenoid during anaerobic growth and demethylspheroidenone when grown in the presence of oxygen, a heretofore undescribed phenotype. The genetic region necessary for O-methylation maps adjacent to the known cluster of genes affecting carotenoid biosynthesis. In addition, we have identified methoxyneurosporene as the carotenoid that preferentially binds to the reaction centers of strain Ga, a green mutant of R. sphaeroides which accumulates three neurosporene-like carotenoids. A metabolic grid for carotenoid biosynthesis is proposed, based upon the intermediates accumulated in these mutants.

Alleles↗
PubMed1977

Nutritive content of college meals. III. Mineral elements.

Two samples, each consisting of two breakfasts, two lunches, and two dinners as offered to college students, were collected for seven consecutive days from each fifty colleges. The composited meals for each college were analyzed for five major mineral elements--calcium, phosphorus, magnesium, sodium, and potassium--and five trace mineral elements--iron, chromium, copper, manganese, and zinc. On a per-person-per-day basis, the meals met or exceeded the recommended dietary allowances for nineteen-to-twenty-two-year-old men and women for calcium and phosphorus. Meals from most of the colleges were below the allowance for magnesium, over nine-tenths were short in zinc, and about three-fifths were below the allowance for iron for females but in only one college for males. Average ratios for mineral element to mineral element are reported.

Adolescent↗
PubMed1976

Nutritive content of college meals. II. Lipids.

Two samples, each consisting of two breakfasts, two lunches, and two dinners as offered to college students, were collected for seven consecutive days from each of fifty colleges. Two samples of the composited meals from each college were analyzed for fat and fatty acids. The fat content of the meals averaged 125.58 gm., with a range of 96.96 to 163.74 gm. This provided an average of 42.33 per cent of total calories, (range, 36.68 to 47.67 per cent). No college served meals with as little as 35 per cent of calories derived from fat. The meals contained an average of 46.3 gm. saturated fatty acids; 48.98 gm. mono-unsaturated fatty acids, of which 48.19 gm. were oleic acid; and 18.25 gm. polyunsaturated fatty acids, of which 17.22 gm. were linoleic acid. Four fatty acids--palmitic (C-16); stearic (C-18); oleic (C-18:1); and linoleic (C-18:2)--contributed approximately 92 per cent of the total fatty acids. The average ratio of polyunsaturated fatty acids to saturated fatty acids was 0.39 (range, 0.22 to 0.69). Six colleges served meals with a P:S ratio of 0.30 or below; five colleges had a P:S ratio of 0.50 or above.

Diet↗
PubMed1975

Nutritive content of college meals. Proximate composition and vitamins.

Two samples, each consisting of menus of two breakfasts, lunches, and dinners, as offered to college students, were collected for seven consecutive days from each of fifty colleges. The composited meals were analyzed to determine proximate composition and content of vitamin A, vitamin D, thiamin, riboflavin, niacin, folacin, vitamin B6, and vitamin B12. On a per-person-per-day basis, the meals met or exceeded the Recommended Dietary Allowances for nineteen-to-twenty-two-year-old men and women for protein, vitamin A, riboflavin, and niacin. About a third of the meals were below the allowances for vitamin D, three-fifths were short in thiamin, and three-fourths were short in folacin and vitamin B6. A number of colleges offered meals that were short on calories.

Adolescent↗
PubMedDate not supplied

Preliminary observations on dissolution and bioavailability of triamterene-hydrochlorothiazide combination products.

The dissolution profiles of two brands of triamterene-hydrochlorothiazide (TRM-HCT) combination tablets and two brands of TRM-HCT combination capsules were studied using the USP paddle method at 100 rev min-1 in acid medium (0.1N). The tablets represent two products marketed in Germany, whereas the capsules represent the approved innovator's product and an unapproved generic product. The tablets dissolved almost 100 per cent in 15 min whereas the capsules dissolved less than 25 per cent in 60 min. A pilot bioavailability study was carried out in four normal healthy male volunteers. Urine samples were collected over a 48 h period and analysed for TRM, its major metabolite TRM-sulfate, and HCT using HPLC methods. The dissolution characteristics of TRM can be associated with the total drug excretion (absorption) of the product. On the other hand, the excretion (absorption) of HCT was independent of dissolution characteristics of the products. However, in TRM-HCT combination product, there appears to be a 50 per cent reduction in HCT excretion (absorption) when compared to the reported excretion (absorption) from a marketed single-entity product.

Biological Availability↗
PubMedDate not supplied

Thiazides XI: partitioning of chlorothiazide in red blood cells after oral administration.

Uptake of chlorothiazide by red blood cells after oral drug administration was investigated. Chlorothiazide was administered to normal healthy volunteers as a solution or a tablet. Frequent blood samples were collected and analysed by a specific HPLC method. The results indicate that there is a significant uptake of chlorothiazide by red blood cells, resulting in a higher blood AUC compared to plasma AUC.

Administration, Oral↗
PubMedDate not supplied

HLA-G1 protein expression is not essential for fetal survival.

HLA-G is a nonclassical, class I HLA gene that is primarily expressed by fetal cells at the maternal-fetal interface and is thought to play a key role in the induction of tolerance in pregnancy. This paper reports the identification of a single base pair deletion at position 1597 (1597delC) in exon 3 (encoding the alpha2-domain) of HLA-G on 20 of 272 (7.4 per cent) African American chromosomes, three of 102 (2.9 per cent) Hispanic chromosomes, and none of 134 Caucasian chromosomes. This relatively common frameshift mutation results in amino acid substitutions in all of the residues in the second half of exon 3 including the conserved cysteine at codon 164. An adult individual was identified who was homozygous for this 'null' allele, and a first trimester placenta that was homozygous for 1597delC had no detectable HLA-G1 protein. These data indicate that expression of HLA-G1 protein is not essential for fetal survival.

Adult↗