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Biomedical subjects

M Pepper

Publications and source records attributed to M Pepper.

At least 73 records · Page 4Linked to original sources
PubMed1993

Genistein, a dietary-derived inhibitor of in vitro angiogenesis.

Consumption of a plant-based diet can prevent the development and progression of chronic diseases that are associated with extensive neovascularization; however, little is known about the mechanisms. To determine whether prevention might be associated with dietary-derived angiogenesis inhibitors, we have fractionated urine of healthy human subjects consuming a plant-based diet and examined the fractions for their abilities to inhibit the proliferation of vascular endothelial cells. Using gas chromatography-mass spectrometry, we showed that one of the most potent fractions contained several isoflavonoids, which we subsequently synthesized. Of all synthetic compounds, the isoflavonoid genistein was the most potent and inhibited endothelial cell proliferation and in vitro angiogenesis at concentrations giving half-maximal inhibition of 5 and 150 microM, respectively. As we have previously demonstrated, genistein concentrations in urine of subjects consuming a plant-based diet are in the micromolar range, while those of subjects consuming a traditional Western diet are lower by a factor of > 30. The high excretion of genistein in urine of vegetarians and our present results suggest that genistein may contribute to the preventive effect of a plant-based diet on chronic diseases, including solid tumors, by inhibiting neovascularization. Thus, genistein may represent a member of a new class of dietary-derived anti-angiogenic compounds.

Adrenal Cortex↗
PubMed1991

In vivo modulation of connexin 43 gene expression and junctional coupling of pancreatic B-cells.

We have explored the expression of gap junctional proteins and corresponding mRNAs by insulin-producing B-cells of native rat pancreas and of a transplantable rat insulinoma. By immunostaining cryostat sections (indirect immunofluorescence) and crude membrane preparations (Western blots) with antibodies against connexins 26, 32, and 43 and by hybridizing total islet and insulinoma RNA (Northern blot) with cRNAs for the latter two proteins, we have found that normal and tumoral B-cells express connexin 43 but do not show detectable levels of either connexin 32 or 26. By evaluating the conductance (dual patch-clamp whole-cell recording) and permeability of junctional channels (microinjection of Lucifer yellow), we have found that control B-cells show low levels of electrical and dye coupling in only a portion of the pairs studied. By studying B-cells of glibenclamide-treated rats, we have found that sustained stimulation of insulin release in vivo is associated with a two-fold increase in the level of connexin 43 gene transcripts and in the incidence of both ionic and dye coupling. These observations indicate that (1) connexin 43 is a major component of communicating channels between insulin-producing cells; (2) some but not all B-cells are electrically coupled by low conductance junctional channels; and (3) connexin 43 gene transcripts and incidence of junctional coupling are modulated in parallel during sustained stimulation of B-cell functioning in vivo.

Animals↗
PubMed1991

Physiological responses at the fatigue threshold.

The purpose of this investigation was to determine the oxygen consumption, heart rate and plasma lactate responses at the fatigue threshold (FT) and estimate the length of time the FT could be maintained. Ten adult males (mean age +/- SD = 21.1 +/- 1.3 yrs) volunteered to perform a maximal treadmill test and FT test. During the maximal test, VO2 heart rate and plasma lactate measurements were taken. The results of the investigation indicated that the FT (14.0 +/- 1.2 km.hr-1, 197 +/- 8 bpm; 47.5 +/- 5.7 ml/kg.min-1, 5.4 +/- 1.3 mM) was very close to a maximal effort (VO2max = 14.4 +/- 1.2 km.hr-1, 203 +/- 10 bpm; 49.5 +/- 6.1 ml/kg.min-1, 7.4 +/- 2.1 mM) and could be maintained for only 0.16 to 0.28 hrs. These findings do not support the validity of the FT as a measure of the maximal running velocity that can be continued for an extended period of time without exhaustion.

Adult↗