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Biomedical subjects

J F Williams

Publications and source records attributed to J F Williams.

At least 217 records · Page 12Linked to original sources
PubMed1981

Hyperplastic gastropathy in the rat due to Taenia taeniaeformis infection: parabiotic transfer and hypergastrinemia.

Development of the cestode parasite Taenia taeniaeformis in the liver of rats results in gross hyperplastic changes in the stomach and small intestine. In this study we investigated the mechanism by which these lesions are induced. Acutely infected rats were joined surgically to syngeneic noninfected partners in parabiosis. When hyperplastic gastropathy developed in those rats with heavy hepatic infections with cestodes, it also occurred in the uninfected partners of the parabiotic pairs. Gastric changes were usually more severe in the uninfected partner. Duodenal mastocytosis developed in both partners, even when parasite burdens were light in the infected rats. intact chronically infected rats with hyperplastic gastropathy developed markedly elevated serum levels of the hormone, gastrin (approximately 30-fold greater than normal). When rats were antrectomized 24-48 h after infection, gastric hyperplasia still developed, but hypergastrinemia was prevented or was of only moderate degree. There was no correlation between serum gastrin levels and the degree of gastrointestinal change in the intact rats, but hypergastrinemia never developed in infected animals which did not show hyperplasia in the stomach or intestine. When infected rats were bled serially over the first 100 days of infection, hypergastrinemia developed abruptly between 50 and 60 days after infection. These results suggest that the alterations in serum gastrin levels were secondary to the development of hyperplastic changes in the gastrointestinal tract of infected rats. The primary stimuli for both the hyperplasia and the hypergastrinemia remain unknown.

Animals↗
PubMed1981

Longevity and productivity of Taenia taeniaeformis in cats.

The longevity and productivity of Taenia taeniaeformis were studied in experimentally infected cats. Nineteen of 20 cats became infected after they were given 8 to 12 strobilocerci. In 8 cats, mean prepatent period was 47.1 days +/- 5.9 SEM (34 to 80 days). Patent periods in the infected cats were 7 to 34 months. In 11 cats in which the infections were allowed to terminate naturally (spontaneous recovery), mean patient period was 17.4 months +/- 2.3. Two of these cats were then given a 2nd dose of strobilocerci and both became reinfected. The mean daily proglottid output in 6 cats followed throughout the patent period was 4.3 +/- 0.5. Destrobilization occurred spontaneously and sporadically throughout the infection, but did not always increase at the time of natural termination. Usually, proglottid productivity began to decrease after the 1st year of infection. Shed proglottids contained 0 to 12,180 eggs, with a mean of 1,606 +/- 402, but more than 60% of the segments contained 500 or less. Taenia taeniaeformis appeared to be as persistent as other taeniids, such as T ovis and T hydatigena in the dog, but it was far less prolific as an egg producer.

Animals↗
PubMed1980

Use of [2-14C]glucose and [5-14C]glucose for evaluating the mechanism and quantitative significance of the 'liver-cell' pentose cycle.

1. Expressions are derived for the steady-state measurement of the quantitative contribution of the liver-type pentose phosphate cycle to glucose metabolism by tissues. One method requires the metabolism of [5-14C]glucose followed by the isolation and degradation of glucose 6-phosphate. The second procedure involves the metabolism of [2-14C]glucose and the isolation and degradation of a triose phosphate derivative, usually lactate or glycerol. 2. Measurements of 14C in C-2 and C-5 of glucose 6-phosphate are required and the values of the C-2/C-5 ratios can be used to calculate the quantitative contribution of the L-type pentose cycle in all tissues. 3. The measurement of 14C in C-1, C-2 and C-3 of triose phosphate derivatives can be used to calculate the quantitative contribution of the L-type pentose cycle relative to glycolysis. 4. The effect of transaldolase and transketolase exchange reactions, reactions of gluconeogenesis and non-oxidative formation of pentose 5-phosphate, isotopic equilibration of triose phosphate pools and isotopic equilibration of fructose 6-phosphate and glucose 6-phosphate, which could interfere with a clear interpretation of the data using [2-14C]- and [5-14C]glucose are discussed.

Carbon Radioisotopes↗
PubMed1980

Quantitative measurement of the L-type pentose phosphate cycle with [2-14C]glucose and [5-14C]glucose in isolated hepatocytes.

1. Investigations of the mechanism of the non-oxidative segment of the pentose phosphate cycle in isolatd hepatocytes by prediction-labelling studies following the metabolism of [2-14C]-, [5-14C]- and [4,5,6-14C]glucose are reported. The 14C distribution patterns in glucose 6-phosphate show that the reactions of the L-type pentose pathway in hepatocytes. 2. Estimates of the quantitative contribution of the L-type pentose cycle are the exclusive form of the pentose cycle to glucose metabolism have been made. The contribution of the L-type pentose cycle to the metabolism of glucose lies between 22 and 30% in isolated hepatocytes. 3. The distribution of 14C in the carbon atoms of glucose 6-phosphate following the metabolism of [4,5,6-14C]- and [2-14C]glucose indicate that gluconeogenesis from triose phosphate and non-oxidative formation of pentose 5-phosphate do not contribute significantly to randomization of 14C in isolated hepatocytes. The transaldolase exchange reaction between fructose 6-phosphate and glyceraldehyde 3-phosphate is very active in these cells.

Animals↗
PubMed1980

Endotoxin depression of hepatic mixed function oxidase system in C3H/HeJ and C3H/HeN mice.

The effect of endotoxin to depress the hepatic drug-metabolizing enzyme activity has been studied in the C3H/HeJ and C3H/HeN strains of mice. The C3H/HeJ mouse strain is generally considered to be unresponsive to the biological effects of endotoxin. However, injection of these mice with 0.5 mg/kg body weight of E.coli endotoxin (Westphal extracted) produced a decrease in the rate of N-demethylation of ethylmorphine and in the levels of cytochrome P-450 and cytochrome b5 comparable to that observed in the endotoxin-sensitive C3H/HeJ mouse strain. Although the mechanism of endotoxin action to decrease hepatic microsomal drug-metabolizing activity is presently unknown, the results suggest that: 1) the C3H/HeJ mouse stain is responsive to this endotoxin effect, and 2)that cellular constituents other than B-cells or macrophages are probably involved in eliciting the response, since these cells of the C3H/HeJ mouse are unresponsive to endotoxin.

Animals↗
PubMed1980

Receptor-binding activity of highly purified bovine luteinizing hormone and thyrotropin, and their subunits.

Highly purified preparations of bovine TSH (bTSH) and LH (bLH) and their subunits have been obtained by affinity chromatography using immobilized antibodies directed against counterpart subunits. The purified preparations were assessed for biological activity in radioligand-receptor assays for TSH and LH. After affinity purification against bLH beta, a TSH preparation whose initial potency in the LH assay had been 0.15% that of LH, failed to compete with [125I]LH in amounts up to 100 microgram. Thus, it appears that bTSH does not bind to LH receptors in the rat testis and that interaction of less purified TSH with gonadotropin receptors is attributable to LH contamination. In contrast, LH, whose initial potency in the TSH receptor assay was 0.6% that of TSH, retained a potency of 0.004% of TSH (equivalent to 3.6 mU/mg) after immunoadsorption by anti-bTSH beta. The retention of TSH receptor-binding activity by affinity-purified LH indicates that the LH molecule (like hCG) has a low intrinsic thyroid-stimulating activity. Affinity-purified LH subunits have little or no demonstrable affinity for the LH receptor in vitro. Affinity-purified TSH subunits and affinity-purified LH, however, exhibit very weak receptor-binding activity in the TSH radioligand receptor assay. An evaluation of the capacity of the immunoadsorbents to remove TSH from artificial mixtures suggests that the residual binding does not result entirely from contamination, and therefore, that alpha-subunits as well as LH have some intrinsic TSH-binding activity.

Animals↗
PubMed1980

Caprine toxoplasmosis: abortion, clinical signs, and distribution of Toxoplasma in tissues of goats fed Toxoplasma gondii oocysts.

Thirteen goats (9 does and 4 bucks) were each inoculated orally with 10,000 infective Toxoplasma gondii oocysts. Three does and one buck were used as noninoculated controls. In 2 to 4 days after inoculation (DAI), inoculated goats became dull, pyrectic (40 to 41 C), and anorectic. Three goats died (10, 10, and 14 DAI) and two goats were killed (7 and 32 DAI) because they were moribund; also, 3 does aborted, 2 had weak kids, and 2 had dead fetuses. Toxoplasma was isolated from the placenta of three goats, and the fetal tissues of four goats. The control goats remained asymptomatic. The distribution of T gondii in blood and other tissues was studied by inoculation of mice with caprine tissues. Parasitemia was detected in 7 of 7 goats--beginning 4 DAI in 1 goat, 5 DAI in 5 goats, and 8 DAI in 1 goat. The parasitemia lasted 3 to 10 days. Toxoplasma was isolated from the milk of 2 goats at 12 and 14 DAI. Toxoplasma was isolated from 15 or more tissues of 5 goats killed 7 to 35 DAI and from 10 tissues of 2 goats killed 69 and 95 DAI.

Abortion, Veterinary↗