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Biomedical subjects

L Brenner

Publications and source records attributed to L Brenner.

At least 19 recordsLinked to original sources
PubMed1992

CCK-receptor antagonists attenuate suppression of sham feeding by intestinal nutrients.

To test the possibility that endogenous cholecystokinin (CCK) participates in suppression of sham feeding by intraintestinal nutrient infusions, we examined the effect of CCK-receptor antagonists on the suppression of sham feeding by intraintestinally infused oleic acid, maltose or L-phenylalanine (L-Phe). In addition, we monitored amylase activity in the intestinal lumen during some sham feeding experiments and measured plasma CCK in parallel experiments using intestinally infused animals that were not feeding. Suppression of sham feeding by oleic acid or maltose was attenuated by CCK-receptor antagonists, while suppression of sham feeding by L-Phe was not. Oleate infusion increased plasma CCK concentration and luminal amylase activity. Oleate-induced increase in luminal amylase activity was attenuated by a CCK-receptor antagonist. Intraintestinal maltose or L-Phe did not increase plasma CCK concentration or luminal amylase activity, suggesting that they did not release endocrine CCK. These results suggest 1) that endogenous CCK mediates suppression of sham feeding by oleate and maltose but not by L-Phe and 2) that CCK participating in suppression of feeding by intestinal stimuli might not be of endocrine origin.

Amylases↗
PubMed1992

Low-dose near-celiac arterial cholecystokinin suppresses food intake in rats.

Exogenous cholecystokinin (CCK) suppresses food intake by acting on vagal sensory neurons. However, CCK doses used in behavioral experiments are generally much larger than those necessary to produce electrophysiological changes in vagal afferents. We made automated measurements of liquid food intake before, during, and after infusion of low doses of CCK octapeptide (CCK-8) through a chronic aortic catheter with its tip seated just above the celiac juncture. In parallel experiments, we made similar infusions while collecting blood from the hepatic portal and jugular veins for CCK assay. Injection of 10, 30, 50, and 70 pmol of CCK-8 suppressed feeding in a dose-dependent manner beginning 1 min postinfusion. The lowest dose to produce statistically significant suppression of preinfusion intake was 30 pmol. Infusion of the same CCK-8 doses into the jugular vein did not suppress feeding. Near-celiac injection of 30 pmol of CCK-8 produced systemic plasma CCK concentrations averaging 6.5 +/- 1 pM compared with less than 1 pM after saline injection. These findings show that exogenous CCK, by acting on tissues perfused by the celiac artery, can suppress feeding at doses that 1) are similar to those producing effects on the firing of vagal neurons and 2) do not increase plasma CCK concentrations above postprandial levels.

Animals↗
PubMed1987

The effect of cyclohexene, a preservative in dichloromethane on the liquid-liquid extraction and analysis of chlorinated drinking water.

Liquid-liquid extraction with dichloromethane is the Environmental Protection Agency's (EPA) method of choice for the analysis of acid or base neutral organic chemicals in water. Free radical chlorination and oxidation products of cyclohexene (the solvent preservative) in dichloromethane have been observed in extracts of chlorinated drinking water (after 10(5) fold concentration) by gas chromatography and gas chromatography-mass spectrometry. The chlorinated cyclohexene derivatives limit the quantitative and qualitative analysis of compounds eluting at Kovát's index less than 700-1000 and the use of these extracts for organoleptic and mutagenic studies. The effect of residual free chlorine in water on the cyclohexene present in the solvent was studied. Over ten cyclohexene derivatives were produced in every case when any residual free chlorine was present in the water. When chlorine is reduced to chloramine, the cyclohexene derivatives were greatly reduced in number and amount.

Chloramines↗
PubMed1985

A measurement of human hair oxidation by Fourier transform infrared spectroscopy.

Human scalp hair samples were oxidized to determine the sulfonic acid absorption peak. This peak was monitored at 1044 cm-1 by Fourier transform infrared spectroscopy (FTIR) in hair samples from 135 whites and found to provide a degree of discrimination in treated and untreated hairs. The effects of moisture, laboratory storage, natural hair color, and variation over time were also studied.

Adolescent↗
PubMed1975

Folic acid deficiency in the United States: folate assays in a prenatal clinic.

Tissue deficiency of folic acid, as measured by a red cell folate level below 150 ng. per milliliter, was present in 16 per cent of 110 sequential pregnant women at the time of their first prenatal visit to a municipal clinic. A further 14 per cent of subjects had red cell folate levels in the range "suggestive but not conclusive for tissue folate depletion" (150 to 199 ng. per milliliter). All of the subjects were from low-income families in New York City and most were black or of Puerto Rican origin. Serum folate levels showed good general correlation with red cell folate but were of less value as a diagnostic test, since they were below the lower limit of normal in 64 per cent of subjects, including many subjects who did not yet have low tissue folate. In contrast to their value in other folate deficiency states, neutrophil lobe counts showed no correlation with serum or red cell folate levels in pregnancy and thus appeared of little diagnostic value in pregnancy. It is suggested that surveys of folate deficiency in other pregnant population groups in the United States be carried out. These results support the recommendations of the Committee on Maternal Nutrition and the Committee on Dietary Allowances of the Food and Nutrition Board, National Research Council (U.S.A.) that folic acid supplements (200 to 400 mug per day) should be taken throughout pregnancy.

Black or African American↗
PubMed1969

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