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Biomedical subjects

R Craven

Publications and source records attributed to R Craven.

14 recordsLinked to original sources
PubMed1994

WAY-100635 and GR127935: effects on 5-hydroxytryptamine-containing neurones.

N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2- pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY-100635) is a potent and selective 5-HT1A receptor antagonist in a slice preparation of the guinea pig dorsal raphe nucleus: the inhibitory actions on 5-HT neuronal firing of 5-hydroxytryptamine (5-HT, serotonin), 5-carboxamidotryptamine (5-CT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), but not those of baclofen, were abolished by 30 nM WAY-100635. The selective 5-HT1D receptor antagonist N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2'- methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl) [1,1-biphenyl]-4-carboxamide (GR127935, 300 nM) did not attenuate the 5-HT induced inhibition, indicating that 5-HT1D receptors do not contribute to the inhibitory action of exogenous 5-HT on 5-HT neurones.

Action Potentials↗
PubMed1992

Effects of the gonadotrophin-releasing hormone agonist 'Zoladex' upon pituitary and gonadal function in hypogonadal (hpg) male mice: a comparison with normal male and testicular feminized (tfm) mice.

Hypogonadal (hpg) mutant mice, with a congenital deficiency of hypothalamic gonadotrophin-releasing hormone (GnRH), and testicular feminized (tfm) mice, which lack a functional androgen receptor, were used to study the effects of the potent GnRH agonist 'Zoladex' (ICI 118630; D-Ser (Bu(t))6, Azgly10-GnRH) on pituitary and gonadal function. Zoladex (0.5 mg) in a sustained-release lactide-glycolide copolymer depot was administered subcutaneously under anaesthesia and was left in place for 7 days, after which time the effects of the drug upon pituitary and serum gonadotrophin concentrations, glycoprotein hormone subunit mRNAs and testicular morphology were investigated. At the pituitary level, Zoladex treatment resulted in a substantial reduction in LH content in normal males, and LH content was depressed in hpg mice even below the basal levels normally found in these mutants. Pituitary LH content in the Zoladex-treated animals was depressed in the tfm groups, but not to the same levels as those found in the normal and castrated normal mice. Zoladex treatment at the time of castration prevented the post-operative elevation in serum LH associated with castration alone. In the androgen-deficient tfm mouse, Zoladex did not depress the normally elevated serum LH levels. Serum LH in the hpg animals was, in all cases, below the limit of detection of the assay. Pituitary FSH content was depressed into the hpg range in both the normal and castrated animals, but there was no further depression in the hpg mice. The pituitary content was reduced in the tfm mice, again the effects not being as dramatic as in the normal and castrated animals. Serum FSH content, as measured by radioimmunoassay, was depressed by 50% in normal mice; there was no reduction in the hpg mice, however. With regard to pituitary gonadotrophic hormone gene expression, Zoladex administration to normal mice caused a dramatic reduction in LH beta mRNA content, to a level approximating that found in untreated hpg mice. The drug also depressed LH beta mRNA in the castrated group to the hpg range when given at the time of castration, whereas in untreated castrated mice there was a significant increase in LH beta mRNA. In the tfm mouse, which can be considered as a model for long-term failure of androgen feedback, Zoladex again induced a fall in LH beta mRNA, but not to the same extent as in the normal and normal castrated group. Zoladex had no effect on the already low levels of LH beta mRNA found in hpg mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Androgens↗
PubMed1991

Characterization of cytokines present in middle ear effusions.

Retention of inflammatory mediators and cells in the middle ear cleft during chronic otitis media with effusion (COME), results in ongoing inflammation with the potential for pathologic changes and hearing loss. Cytokines are glycoproteins produced by macrophages and other cells. Activities of cytokines include fever production, osteoclast, fibroblast, phagocyte and cytotoxic cell activation, regulation of antibody formation, and inhibition of cartilage, bone and endothelial cell growth. Using enzyme-linked immunospecific assays we measured levels of six cytokines in middle ear effusions (MEE) from children with COME. Significant levels of four cytokines: interleukin-1-beta (greater than 50 pg/ml), interleukin-2 (greater than 300 pg/ml), tumor necrosis factor-alpha (greater than 40 pg/ml), and gamma-interferon (greater than 6.25 pg/ml) were found in 51%, 54%, 63%, and 19% of MEE, respectively. In contrast, levels of a fifth cytokine, granulocyte-macrophage colony-stimulating factor, and a sixth cytokine, interleukin-4, were undetectable. Age was observed to have a significant effect on the levels of specific cytokines. Interleukin-1 (IL-1) correlated inversely (P less than .02) with age such that the younger the child, the higher the level of IL-1 in MEE. Tumor necrosis factor-alpha (TNF) correlated directly (P less than .005) with age such that the older the child, the higher the level of TNF in MEE. Children undergoing tympanostomy on multiple occasions had average MEE TNF levels (234.2 +/- 109.1 pg/mg total protein) that were nearly 14 times higher (P less than .005) than those from children undergoing their first tympanostomy (16.9 +/- 3.0 pg/mg total protein). Thus IL-1 correlated with the early stages of COME, while TNF correlated with persistence of disease. The presence of these cytokines in MEE may be responsible for the mucosal damage, bone erosion, fibrosis, and resulting hearing loss seen in some cases of COME.

Aging↗
PubMed1990

Monoclonal and polyclonal antibodies reactive with the 1-32 amino terminal sequence of the alpha subunit of human 32K inhibin.

A monoclonal antibody was made after immunization of mice with the 1-32 amino terminal peptide of the alpha subunit of 32K human ovarian inhibin. The IgG2a mouse antibody reacted 6 times better with bovine 1-32 peptide than it did with 32K bovine inhibin. By contrast sheep polyclonal antibodies made by a similar method had a 29 fold bias in reactivity towards the immunizing peptide. Relative to homologous 1-32 peptide standards, the monoclonal antibody measured apparently higher amounts of immunoreactive material(s) in human (13.5 fold) and bovine (27 fold) follicular fluids than did the polyclonal anti 1-32 peptide antibodies. Immunochemical studies revealed that the epitope recognized by the monoclonal antibody was different from the major epitope recognized by the polyclonal antibodies. The monoclonal antibody reacted much better with human inhibin 1-32 sequences than with bovine (73 fold) or porcine (23 fold). Although the 32K form of human inhibin has not yet been purified, it can be inferred that the monoclonal antibody would be able to detect as little as 2 ng/ml of 32K human inhibin in competitive radioimmunoassays. The antibody must also react with some of the multiple molecular forms of inhibin found in human follicular fluids, and it was shown to function well in the quantitative immunoaffinity extraction of inhibin-like immunoreactivity from follicular fluid. It seems likely that this monoclonal antibody will prove a useful tool for research on human inhibin.

Amino Acid Sequence↗
PubMed1985

Regulation of Pseudomonas aeruginosa chemotaxis by the nitrogen source.

The regulation of amino acid chemotaxis by nitrogen was investigated in the gram-negative bacterium Pseudomonas aeruginosa. The quantitative capillary tube technique was used to measure chemotactic responses of bacteria to spatial gradients of amino acids and other attractants. Chemotaxis toward serine, arginine, and alpha-aminoisobutyrate was sharply dependent on the form in which nitrogen was presented to the bacteria. Bacteria grown on mineral salts-succinate with potassium nitrate gave responses to amino acids that were 2 to 3 times those of cells grown on ammonium sulfate and 10 to 20 times those of cells grown in mineral salts-succinate with Casamino Acids as the nitrogen source. A combination of ammonium sulfate and glutamate was as effective as Casamino Acids in depressing serine taxis. The threshold concentration for alpha-aminoisobutyrate taxis was consistently lower in nitrate-grown bacteria than in ammonia-grown bacteria. Responsiveness to sodium succinate, however, was not subject to regulation by nitrogen, and glucose chemotaxis was inhibited, rather than enhanced, in nitrate-grown bacteria. These results indicate that chemotaxis of P. aeruginosa toward amino acids is subject to regulation by nitrogen and that this regulation probably is expressed at the level of the chemoreceptors or transducers.

Amino Acids↗
PubMed1981

Trace minerals, amino acids, and plasma proteins in adult men fed wheat diets.

In summary, the ingestion by adult men of an all-plant diet supplying 46 gm. protein per day, primarily as bread made from white wheat four, over a period of 74 days, resulted in positive balances for copper, iron, molybdenum, selenium, and zinc. Iron balances were significantly decreased by the isonitrogenous substitution of pinto beans or peanut butter for 20 percent of the nitrogen supplied by white bread. When pinto beans or white rice substituted for 20 percent of the nitrogen of white bread, the retention of molybdenum was lower and the retention of selenium was greater. Although the men were nitrogen balance and total plasma protein concentrations were normal, the ingestion of diets providing 46 gm. protein, from all-plant sources resulted in significantly lower plasma albumin, with corresponding elevations in alpha, beta and gamma globulins. However, the substitution of pinto beans for a portion of the white bread improved plasma albumin and alpha-globulin levels. Routine clinical data obtained on patients who previously consumed strictly vegetarian diets should include determinations of plasma albumin. The ability of the subjects to maintain nitrogen balance on protein intakes of 46 gm. per day from all-plant sources appeared to be correlated with decreases in the urinary excretion and plasma concentration of alpha-aminobutyric acid, a metabolite of methionine and threonine, suggesting conservation of methionine or re-utilization of this metabolite. The possible mechanism of this adaptation to minimal protein intake, or dietary protein from all-plant sources, is discussed.

Adult↗
PubMed1976

Urinary tract infections in patients with severe renal disease. Treatment with ampicillin and trimethoprim-sulfamethoxazole.

Twelve patients with severe renal failure and intercurrent urinary tract infections were treated with either ampicillin trihydrate, 500 mg four times a day, or trimethoprim-sulfamethoxazole, two tablets (80 mg trimethoprim, 400 mg sulfamethoxazole) twice a day. All patients achieved bacteriologic cure, including six with proved upper tract infection. Serum levels of all drugs were increased to values above those seen in normal subjects without adverse effects. Urine concentrations of trimethoprim, 28.6 mug/ml, and ampicillin, 88.6 mug/ml, were well above the minimum inhibitory concentrations of urinary pathogens. Urine sulfamethoxazole concentrations were less than 10 mug/ml in four of the six patients treated; however, this did not hamper bacteriologic success. It is concluded that both drugs can be used to treat urinary tract infections in patients with renal functional impairment.

Adult↗