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D Gilbert

Publications and source records attributed to D Gilbert.

At least 73 records · Page 4Linked to original sources
PubMed1976

Application of an in-vitro perifusion technique to studies of luteinizing hormone release by rat anterior hemi-pituitaries: Self-potentiation by luteinizing hormone releasing hormone.

A technique is described for the continuous perifusion of rat adenophypophyses. Exposure of the perifused glands to repeated equal 5 min stimuli with hypothalamic extract resulted in a series of equal peaks of corticotrophin secretion, the response was proportional to log dose over the range 0 - 25-2 - 0 rat hypothalamic equivalents/ml. Repeated equal stimuli with hypothalamic extract, or with luteinizing hormone releasing hormone (LH-RH) at concentrations of 2 or 10 ng/ml, resulted in a progressively increasing series of peaks of LH secretion, i.e. a self-potentiating or priming effect. The effect took between 30 min and 1 h to develop. A delayed increase in the responsiveness of the glands was also seen with continuous incubation of anterior pituitaries with LH-RH. The relevance of these observations to the physiological control of LH secretion is discussed.

Adrenocorticotropic Hormone↗
PubMed1976

Effect of sodium intake on gentamicin nephrotoxicity in the rat.

Gentamicin nephrotoxicity was examined in rats on normal, high, and low sodium diets. Low sodium diet markedly potentiated nephrotoxic effects of the drug as evidenced by animal mortality, renal failure, pathological changes, and increased renal cortical concentration of the drug. High sodium intake reduced the cortical concentration of gentamicin but renal function and ultrastructure were similar to normally fed rats given in the same dose.

Animals↗
PubMed1975

Pseudosymmetry in the structure of luteinizing hormone-releasing hormone. Studies on a series of novel analogs.

Pseudosymmetry in the LH-RH structure is described. Eleven analogs of LH-RH (SMALLER THAN Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) have been synthesized by the fragment condensation method and the repetitive excess mixed anhydride method. Multiple substitutions have been made in the LH-RH sequence, which retain the pseudosymmetry of the LH-RH molecule, while presenting fewer problems of synthesis than the corresponding residues in the natural decapeptide. Thus Trp3, Ser4, Tyr5, Gly6, Leu7, and Arg8 residues were replaced by amino acids having similar properties to the residues that they replace. In all but one of the peptides the Gly10-NH2 residue was replaced by ethylamide, while in the remaining peptide, 1-methyl-5-aminomethyltetrazole (AMT-Me) was substituted at position 10. The compounds were assayed in vitro and in vivo. The following analogs had in vivo and in vitro activities in the range 1-28 percent relative to LH-RH: I, smaller than Glu-His-Phe-Ala-Tyr-Gly-Leu-Arg-Pro-NHEt; II, smaller than Glu-His-Phe-Gly-Tyr-Gly-Leu-Arg-Pro-NHEt; VII, smaller than Glu-His-Phe-Ala-Tyr-Gly-Phe-Arg-Pro-NHEt; IX, smaller than Glu-His-Phe-Ala-Tyr-D-Ala-Leu-Arg-Pro-NHEt; XI, smaller than Glu-His-Phe-Gly-Tyr-Gly-Leu-Arg-Pro-AMT-Me.

Amino Acid Sequence↗
PubMed1975

Forecasting the antimalarial activities of arylamidinoureas from their measured physicochemical properties.

1 The octanol : water partition coefficient (PC), protein binding coefficients to albumin (Ba) and haemoglobin (Bh), proton magnetic resonance (PMR) chemical shifts and pKa of 8 arylamidinoureas have been measured. 2 There were statistically significant correlations for 7 of the 8 compounds between the predicted lipophilicity parameter eta and log PC, Ba and Bh, and also between Hammett's electronic parameter sigma and the PMR and pKa observations. 3 3-Chloro,4-nitrophenylamidinourea showed a larger deviation from these correlations than any other compound. Geometric calculations based on the covalent radii and bond angles of the molecule suggested that the neighbouring chloro and nitro substituents were interacting sterically. 4 Molecular orbital calculations and the observed ultra-violet spectrum provided further evidence for such an interaction, and suggested that the nitro group is twisted out of the plane of the benzene ring in this molecule. 5 Such steric interactions can introduce an additional source of error when attempts are made to correlate the biological and predicted physicochemical properties of compounds. 6 Generalized parameters such as eta and sigma cannot be used with confidence to predict the properties of compounds in which such steric interactions occur.

Amidines↗