Publications by authors named "Bornstein J"

A review of the theoretical basis on which amino acid intravenous solutions are formulated leads to the conclusion that the first class protein model is not ideal for the very small premature infant. Comparison of the serum and urine amino acid levels in a controlled trial between intravenous feeding with "Vamin" and intragastric milk feeding, and further comparison of these values with the cord blood values of premature infants supports the conclusion that the first class protein model is not ideal. The balance studies also support the view that the urinary output of amino acids, as well as the serum levels, should be taken into account in determining the ideal amino acid input.

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When ejected microelectrophoretically near spinal interneurones of cats anaesthetised with pentobarbitone and under conditions where postsynaptic excitability was maintained artificially at a constant level, (-), but not (+), -baclofen selectively reduced monosynaptic excitation by impulses in low threshold muscle (Ia and Ib) and cutaneous (Aalpha) afferents. Polysynaptic excitation of interneurones and Renshaw cells by impulses in higher threshold afferents was less affected, and baclofen had little or no effect on the cholinergic monosynaptic excitation of Renshaw cells. Glycinergic and gabergic inhibitions of spinal neurones were relatively insensitive to baclofen.

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A series of synthetic peptides corresponding to the amino-terminal sequence of human growth hormone (hGH) has been studied for insulin-potentiating effects using three different bioassay systems: (1) intravenous insulin tolerance tests, (2) insulin binding to specific receptors of hepatic plasma membranes and isolated hepatocytes, and (3) modulation of insulin-dependent glycogen synthase and glycogen phosphorylase in muscle and adipose tissue. The results establish that the minimum active sequence is the hexapeptide (hGH 8-13) containing H2N-Arg-Leu-Phe-Asp-Asn-Ala-COOH and strongly indicate that the insulin-potentiating action of the active peptides is to increase the binding of insulin to specific receptors and thus modulate the action of glycogen synthase and phosphorylase, producing hypoglycemia as the result of increased glycogen storage in liver, muscle, and adipose tissue.

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The effects have been investigated of anesthetic and convulsant barbiturates on the spontaneous and potassium-stimulated efflux of [3H]D-aspartate from rat cortex minislices. In concentrations (100 microM) which have previously been shown to alter calcium ATPase activity in synaptosomes, anaesthetic barbiturates depressed and convulsant barbiturates stimulated the spontaneous efflux of [3H]D-aspartate in a dose-dependent manner. The effects on the efflux of [3H]D-aspartate evoked by 44.

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D- and L-5-aminohex-2-enedioic acid (AHED) and the DL-2-bromo derivative, which are conformationally restricted analogues of the excitatory amino acid antagonist D-alpha-aminoadipic acid (D alpha AA), were tested microelectrophoretically on cat spinal neurones. D-AHED reduced the excitatory action of N-methyl-D-aspartate (NMDA) to a greater extent than that of L-glutamate and the potency of this action was a half to a third that of D alpha AA. The DL-2-bromo derivative excited neurons, an effect greater than that of L-glutamate and not blocked by either D alpha AA or L-glutamic acid diethyl ester.

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The hypoglycemic activity of the synthetic peptide fragment of human growth hormone, hGH 1--15, is insulin dependent, although it does not alter the circulating levels of plasma insulin in normal and diabetic rats. In severe diabetes induced by streptozotocin, the peptide had no effect on the basal levels of blood glucose, but enhanced insulin sensitivity during intravenous insulin tolerance tests in 16-h-fasted rats. Radioreceptor binding studies show increased binding of insulin by hepatic plasma membranes prepared from rats pretreated with hGH 1--15.

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HLA antigens were determined in 169 Australian patients with insulin dependent diabetes mellitus (IDDM). HLA-B8 (47.9% v.

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The effects of morphine on synaptic transmission through the inferior mesenteric ganglion (IMG) were studied using intracellular recording techniques. Morphine produced a reversible, dose-dependent reduction in the quantal content of the synaptic potentials with little or no effect on quantal size or the properties of the ganglion cells. This effect of morphine was antagonized by naloxone suggesting the presence of specific preganglionic opiate receptors.

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Dihydrokainate, an inhibitor of high affinity L-glutamate as an excitant of cat spinal neurones in vivo. This action of dihydrokainate was selective in that the effects of excitants taken up actively in vitro by CNS tissue (L-aspartate, D- and L-glutamate and L-homocysteate) were enhanced whereas those of other substances not taken up (acetylcholine, D-homocysteate, kainate and N-methyl-D-aspartate) were not. Since kainate and dihydrokainate have similar potencies as inhibitors of L-glutamate uptake, interference with the inactivation of synaptically released L-glutamate may contribute to the neurotoxic effects of kainate.

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The hypothesis that perceived pain intensity can influence placebo analgesia was tested. One hundred and seven subjects rated their pain from from 0 to 10 on a visual analog scale after a standard wisdom tooth extraction. The expected course of such postoperative pain in the absence of therapy or placebo is a steady increase; this was confirmed by blind administration of the placebo.

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1. The effects of hypertonic solutions on spontaneous transmitter release at synapses in the hypogastric ganglia of guinea-pigs were studied using intracellular recording techniques. 2.

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Three peptides corresponding to the C-terminal region of human growth hormone have been synthesized by the solid-phase method: HGH-(177--191), HGH-(178--191) and HGH-(179--191). The diabetogenic activities of these synthetic peptides are reported. The data indicate that extension of HGH-(179--191) at its NH2-terminus is required for in vivo activity.

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The effect of polypeptides containing the human growth hormone sequence 177--191 on the glucose metabolism of isolated islets of Langerhans has been investigated. It has been found that such peptides accelerate the incorporation of hydrogen at carbon atom 5 into water while accelerating the flux (1-14C oxidation) through the pentose phosphate shunt and inhibiting the oxidation of [6-14C]glucose. The latter inhibition was found not to be due to inhibition of the pyruvate dehydrogenase complex, and it was further found that the previously demonstrated potentiation of glucose-induced insulin release by the peptides was independent of energy provision because none of the glyceraldehyde, pyruvate, or leucine could substitute for glucose.

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The effect of delta-aminolevulinic acid (ALA) on neuromuscular transmission were studied. High concentrations (0.6 to 18 mM) of ALA caused significant reductions in the amplitudes of curarized end-plate potentials (epps).

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Acute effects of two part sequences of human growth hormone on the in vivo activity levels of hepatic glycogen synthase and glycogen phosphorylase were examined. The peptide corresponding to residues 6 to 13 of the hormone (hGH 6--13) decreased the percentage of phosphorylase in the active form without affecting synthase activity. This action was indirect and dependent upon insulin.

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1. A study was made of some properties of the spontaneous synaptic potentials recorded in cells of the hypogastric ganglia of guinea-pigs. 2.

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The synthetic peptides corresponding to amino acids 172-191, 176-191, 177-191, 178-191, 179-191, and 180-191 of human growth hormone (hGH) have been studied for their in vivo effects in normal rats. Four of the peptides (hGH 172-191, 176-191, 177-191, and 178-191) produced a short-lived rise in blood glucose and a more sustained rise in plasma insulin, whereas the other two (hGH 179-191 and 180-191) were inert in the systems tested. A single dose (5 nmol/kg body wt) of the peptides containing the amino acids sequence 178-191 of the hGH molecule significantly reduced insulin sensitivity of the animals in intravenous insulin tolerance tests.

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Synthetic fragments representing the C-terminal end of the growth hormone molecule have been tested for their direct in vitro effects on insulin release by isolated rat islets of Langerhans. hGH 177-191 caused a dose-related potentiation of glucose-induced insulin release, whereas the peptide by itself caused no stimulation of insulin release from the islets. The rate curves constructed for insulin secretion as a function of extracellular glucose concentration showed that the Km for glucose is not altered in the presence of the peptide, but that the Vmax of secretion is increased.

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