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Biomedical subjects

C A Jones

Publications and source records attributed to C A Jones.

At least 217 records · Page 12Linked to original sources
PubMed1983

Influence of age on the temperature response of chickens to Escherichia coli and Salmonella typhimurium endotoxins.

An experiment was conducted to investigate the influence of age on the temperature responses of chickens given bacterial endotoxins. Broiler cockerels 1 to 8 weeks of age received a single intravenous injection of either distilled water (controls), Escherichia coli 0127:B8, or Salmonella typhimurium endotoxins. Rectal temperatures were recorded before and after injection, the birds were placed in an environmental chamber preheated to 33 C, and thereafter rectal temperatures were taken every 30 min for 180 min. In one-week-old chicks, a significant temperature loss was found 30 min after E. coli treatment, and this was followed 60 min later by a significant increase in rectal temperature. The E. coli and S. typhimurium treatments caused a .4 and .5 C increase, respectively, in 2-week-old chicks. Birds aged 3 to 8 weeks developed fevers with maximum changes in rectal temperatures ranging from .3 to 1.6 C. Seven- and eight-week-old chicks developed the highest and most persistent fevers. The febrile response of 5 to 8 week-old chicks was of longer duration than that of younger chicks. It was concluded that the febrile response following endotoxin administration is affected by age.

Age Factors↗
PubMed1983

A classification and review the causes of discharging sockets.

This paper presents a classification of the causes of socket discharge with a review of new patients attending the Prosthetic Clinic. The aim of classifying socket discharge is to allow more accurate diagnosis of its cause and thus more effective treatment of this distressing symptom.

Conjunctivitis↗
PubMed1982

Peripherally administered cations do not modify febrile responses induced in chickens by Escherichia coli.

Two experiments were conducted to investigate the effects on intramuscular injections of Escherichia coli strains B and W on rectal temperature in broiler chicks and to investigate the effects of various cations on the temperature response. In Experiment 1, 4 birds were randomly assigned to each of three treatments. Control birds received a dextrose (50 mg/100 ml) solution and treated birds received a suspension of either E. coli B or E. coli W lyophilized cells (100 mg/kg) in a volume of 2 ml/kg. Rectal temperatures were recorded before injection and thereafter every 4 hr for a period of 24 hr. In Experiment 2, 10 birds were assigned randomly to each of two treatments. Birds received intramuscularly 2 ml/kg body weight injections of either dextrose (50 mg/100 ml) solution or a suspension of E. coli B lyophilized cells (100 mg/kg) in a volume of 2 ml/kg. At 16 hr after injection, rectal temperatures were recorded and birds were divided into the following treatments with 5 birds per group. Birds previously receiving dextrose (50 mg/100 ml) were given intramuscular injections (2 ml/kg body weight) of demineralized distilled water or a 2 ml/kg injection of .5 M solution of either Na+, K+, Ca+2, or Mg+2 made from their chloride salts. Birds previously receiving E. coli B were given intramuscular injections (2 ml/kg body weight) of demineralized distilled water or an injection of a .5 M solution of either Na+, K+, Ca+2, or Mg+2. Five birds served as uninjected controls. Rectal temperatures were taken every 30 min for 90 min thereafter. In Experiment 1, intramuscular injections of E. coli B and E. coli W resulted in an initial fall in rectal temperatures of chickens followed by a rise after 4 hr that peaked at 16 hr postinjection and at 24 hr remained significantly above preinjection values. The injection of the cations Na+, K+, Ca+2, or Mg+2 in Experiment 2 did not significantly affect the febrile response produced by E. coli B.

Animals↗
PubMed1981

The relationship between the carcinogenicity and mutagenicity of nitrosamines in a hepatocyte-mediated mutagenicity assay.

A quantitative relationship was established for 26 nitrosamines between their carcinogenic effectiveness in experimental animals and their mutagenic activity in a mammalian cell-mediated assay. Mutagenesis was measured in Chinese hamster V79 cells co-cultivated with primary rat hepatocytes, which are capable of activating nitrosamines. Resistance to ouabain and to 6-thioguanine served as the genetic markers.

Animals↗
PubMed1981

Rectal temperature and blood chemical responses of young chickens given E. coli endotoxin.

Two experiments were conducted to investigate the effect of intravenous injections of bacterial endotoxin in broiler chicks. In both experiments 5-weeks-old chicks were given a single intravenous injection of either distilled water (control) or 1 mg/kg Escherichia coli endotoxin (serotype 0.127:B8) in a volume of 1 mg/kg. In Experiment 1 rectal body temperatures were taken every hour for 24 hr postinjection. In Experiment 2, rectal temperatures and blood samples were taken at 3, 6, 9, 12, 15, and 24 hr following the administration of endotoxin. Hematocrits and plasma glucose, protein, sodium, potassium, magnesium, calcium, and inorganic phosphorus were measured at each time interval. Birds receiving endotoxin showed a significant increase in rectal temperature from 2 hr until 17 hr postinjection. The febrile response was biphasic with temperatures peaking at 3 to 5 hr and again at 9 to 12 hr. No significant changes in hematocrits occurred following endotoxin injection. Plasma protein, potassium, and calcium decreased significantly, while glucose increased significantly after endotoxin administration. No significant changes in plasma magnesium, sodium, or inorganic phosphorus were observed in endotoxin-treated chicks.

Animals↗
PubMed1980

The non-covalent binding of benzo[a]pyrene and its hydroxylated metabolites to intracellular proteins and lipid bilayers.

The non-covalent interactions of benzo[a]pyrene (BP) and several of its hydroxylated metabolites with ligandin, aminoazodye-binding protein A (Z-protein, fatty acid binding protein) and lecithin bilayers have been studied by equilibrium dialysis, an adsorption technique and fluorescence spectroscopy. Binding affinities expressed as v/c (where v = moles of BP or BP metabolite bound per mole of protein or lipid and c = unbound concentration), were measured at concentrations sufficiently low that there was no self-association of the unbound compounds as judged by their fluorescence characteristics. 3-Hydroxybenzo[a]pyrene (BP-3-phenol), 4,5-dihydro-4,5-dihydroxybenzo[a]pyrene (BP-4,5-dihydrodiol) and 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene (BP-7,8-dihydrodiol) bind more strongly (v/c = 10(5)-5 x 10(5) l x mol-1) to all three binders than does BP itself (v/c = 10(4)-7 x 10(4) l x mol-1). 9,10-Dihydro-9,10-dihydroxybenzo[a]pyrene (BP-9,10-dihydrodiol) binds to ligandin with an affinity similar to those of the other BP metabolites studied here, but binds much less strongly to both protein A and lecithin (v/c = 10(4) and 3 x 10(4) x mol-1, respectively). The low affinity of BP-9,10-dihydrodiol for lecithin would account for earlier findings that on incubation of BP with isolated rat hepatocytes, this metabolite egressed from the cells to the extracellular medium much more readily than either BP-4,5-dihydrodiol or BP-7,8-dihydrodiol. Calculations based on these results suggest that within hepatocytes BP and its metabolites, including BP-9,10-dihydrodiol, will be found almost exclusively associated (> 98%) with lipid membranes.

Adsorption↗
PubMed1980

The use of liver cell cultures in mutagenesis studies.

A sensitive cell-mediated assay has been developed for testing the mutagensis of liver carcinogens. Mutagenesis was detected in Chinese hamster V79 cells that were cocultivated with hepatocytes isolated after collagenase/hyaluronidase digestion of rat liver slices. Mutations were characterized by resistance to ouabain and 6-thioguanine. Seven of the nitrosamines, which are potent liver carcinogens, exhibited a mutagenic response. Mutagensis with the carcinogens could be detected at micromolar doses. The polyaromatic hydrocarbon benzo(a)pyrene, which is not a liver carcinogen, but can cause fibrosarcomas, was not mutagenic in this assay, but was mutagenic in a fibroblast-mediated assay. The liver carcinogen, aflatoxin B1, which usually does not induce fibrosarcomas, exhibited an inverse situation; it was mutagenic for V79 cells in the presence of liver cells but not in the presence of fibroblasts. We suggest that the use of various cell types, including hepatocytes prepared by the slicing method for carcinogen metabolism, and mutable V79 cells offers a sensitive assay for determining the mutagenic potential of chemical carcinogens, and may also allow a study of their organ specificity.

Aflatoxin B1↗
PubMed1980

A sensitive hepatocyte-mediated assay for the metabolism of nitrosamines to mutagens for mammalian cells.

A sensitive cell-mediated assay has been developed for testing mutagenesis in Chinese hamster V79 cells by carcinogenic nitrosamines. Mutations were characterized by resistance to ouabain and 6-thioguanine. Since V79 cells do not metabolize nitrosamines, mutagenesis in the V79 cells was tested in the presence of primary hepatocytes capable of metabolizing nitrosamines. The hepatocytes were isolated after collagenase and hyaluronidase digestion of liver slices. All seven liver carcinogens of the nine tested nitrosamines exhibited a mutagenic response in this cell-mediated assay. The potent liver carcinogens nitrosodimethylamine, nitrosodiethylamine, nitrosoethylmethylamine, and nitrosodipropylamine could be detected with doses as low as 1 muM. The noncarcinogenic nitrosodiphenylamine was not mutagenic. Nitrosomethoxymethylamine was the only nitrosamine that exhibited mutagenic activity in the absence of hepatocytes, and this activity was diminished in the presence of hepatocytes. It is suggested that the use of hepatocytes prepared by the slicing method for carcinogen metabolism and mutable V79 cells offers a highly sensitive assay for determining the mutagenic potential of carcinogenic nitrosamines and probably of other classes of hazardous chemicals occurring in the environment.

Animals↗
PubMed1979

The early effects of chemical carcinogens on adult rat hepatocytes in primary culture: I. Quantitative changes in intracellular enzyme activities following a single dose of carcinogen.

The effects of exposure of adult rat hepatocytes to chemical carcinogens have been studied using a short-term maintenance culture system. Scanning microdensitometry was used to quantitate the observed changes in enzyme activity. The dose-response curves showed a biphasic response for all 4 enzymes studied (glucose-6-phosphate dehydrogenase, succinate dehydrogenase, NADPH oxidase and gamma-glutamyl transpeptidase) there being decreased enzyme activities at the higher dose levels used, possibly indicating cytotoxicity. The enhancement of enzyme activity at low dose levels was due to generalised increases occurring in every cell, rather than to selection of a cell species particularly high in enzyme activity. A culture period of 24 h was necessary for the complete adaptation of the cells to the culture environment as evidenced by the response of intracellular glucose-6-phosphate dehydrogenase activity to carcinogen treatment. These findings are discussed in relation to previously reported in vivo studies.

Animals↗
PubMed1978

A comparison of drug-metabolizing capability in isolated viable rat hepatocytes and renal tubule fragments.

1. The metabolism of a number of xenobiotics has been investigated in isolated viable rat hepatocytes and kidney tubule fragments in suspension. 2. The level of Phase I metabolism was very low in the kidney cells although such cells possess appreciable Phase II metabolic capacity. 3. These findings are discussed in relation to the physiological role of cytochrome P-450 and the conjugating enzymes, and the value of intact cells systems in assessing inter-organ differences in xenobiotic metabolism.

Animals↗