Chromium is an essential nutrient involved in normal carbohydrate and lipid metabolism. The chromium requirement is postulated to increase with increased glucose intolerance and diabetes. The objective of this study was to test the hypothesis that the elevated intake of supplemental chromium is involved in the control of type 2 diabetes. Individuals being treated for type 2 diabetes (180 men and women) were divided randomly into three groups and supplemented with: 1) placebo, 2) 1.92 micromol (100 microg) Cr as chromium picolinate two times per day, or 3) 9.6 micromol (500 microg) Cr two times per day. Subjects continued to take their normal medications and were instructed not to change their normal eating and living habits. HbA1c values improved significantly after 2 months in the group receiving 19.2 pmol (1,000 microg) Cr per day and was lower in both chromium groups after 4 months (placebo, 8.5 +/- 0.2%; 3.85 micromol Cr, 7.5 +/- 0.2%; 19.2 micromol Cr, 6.6 +/- 0.1%). Fasting glucose was lower in the 19.2-micromol group after 2 and 4 months (4-month values: placebo, 8.8 +/- 0.3 mmol/l; 19.2 micromol Cr, 7.1 +/- 0.2 mmol/l). Two-hour glucose values were also significantly lower for the subjects consuming 19.2 micromol supplemental Cr after both 2 and 4 months (4-month values: placebo, 12.3 +/- 0.4 mmo/l; 19.2 micromol Cr, 10.5 +/- 0.2 mmol/l). Fasting and 2-h insulin values decreased significantly in both groups receiving supplemental chromium after 2 and 4 months. Plasma total cholesterol also decreased after 4 months in the subjects receiving 19.2 micromol/day Cr. These data demonstrate that supplemental chromium had significant beneficial effects on HbA1c, glucose, insulin, and cholesterol variables in subjects with type 2 diabetes. The beneficial effects of chromium in individuals with diabetes were observed at levels higher than the upper limit of the Estimated Safe and Adequate Daily Dietary Intake.

To evaluate the possible effects on insulin function, 49 herb, spice, and medicinal plant extracts were tested in the insulin-dependent utilization of glucose using a rat epididymal adipocyte assay. Cinnamon was the most bioactive product followed by witch hazel, green and black teas, allspice, bay leaves, nutmeg, cloves, mushrooms, and brewer's yeast. The glucose oxidation enhancing bioactivity was lost from cinnamon, tea, witch hazel, cloves, bay leaf and allspice by poly(vinylpyrrolidone) (PVP) treatment, indicating that the active phytochemicals are likely to be phenolic in nature. The activity of sage, mushrooms, and brewers's yeast was not removed by PVP. Some products such as Korean ginseng, flaxseed meal, and basil have been reported to be effective antidiabetic agents; however, they were only marginally active in our assay. Our technique measures direct stimulation of cellular glucose metabolism, so it may be that the active phytochemicals in these plants improve glucose metabolism via other mechanisms or that this in vitro screening is not a reliable predictor of hypoglycemic effects in vivo for some products. In summary, the positive effects of specific plant extracts on insulin activity suggest a possible role of these plants in improving glucose and insulin metabolism.

1H nuclear magnetic resonance (NMR) spectra at 270 MHz of gene 5 protein from bacteriophage fd and its complexes with tetra- and octadeoxynucleotides show that approximately 12 of the 37 aromatic protons of the protein undergo upfield shifts upon nucleotide binding. In the complex with d(pT)8, the upfield shifts of the aromatic protons average approximately 0.3 ppm, while in the d(pA)8 complex the same resonances (assigned to tyrosyl protons) shift upfield approximately 0.8 ppm. These are interpreted as ring current shifts induced by stacking of the phenyl rings of three of the five tyrosyl residues with the bases of the nucleotides. 19FNMR of m-fluorotyrosyl gene 5 protein shows five separate resonances: two downfield from m-fluorotyrosine corresponding to "buried" tyrosyls and three near m-fluorotyrosine corresponding to "surface" tyrosyls. The latter (assigned to Tyr-26, -41, and -56, shown by chemical modification to be exposed to solvent) move upfield on nucleotide binding. The downfield 19F resonances are unaffected. Thus the aromatic protons shifted upfield on nucleotide binding appear to be those of Tyr-26, -41, and -56. In contrast to tetra-, octanucleotide binding to gene 5 protein induces large changes in the 1H resonances of the -CH3 groups of the Val, Leu, and Ile side chains. These may reflect conformational changes induced by protein-protein interactions between two monomers bound to the octanucleotide. 1H resonances of the epsilon-CH2 groups of the lysyl residues in the protein and the complexes with nucleotides are narrow with long T2 values, suggesting considerable rotational motion. Thus epilson-NH3+-phosphate interactions, if they occur, are on the surface of the complex and allow the epsilon-CH2 groups to retain considerable rotational freedom. 31P NMR of the bound nucleotides shows large decreases in T1 for the 3'-5' diesters, but little chemical shift suggesting no unusual distortion of the nucleotide backbone on binding to gene 5 protein. A three-dimensional model of a gene 5 protein-octanucleotide complex has been built based on predictions of the secondary structure from the amino acid sequence (87 AA) and tertiary folding dictated by known chemical and NMR features of the complex.

In a recent Letter [1], Johnson, Herring, and Van de Walle (JHV) have concluded that interstitial H in Si has two energy levels in the gap, the acceptor level being lower than the donor level, implying that H is a negative-U impurity.The (0/+) levelassociated with H at the bond-centered (BC) site (Hiic and Hiic)is placed near E, -0.2 eV by deep-level transient spectroscopy (DLTS) [2] measurements, a value close to that recently obtained from RF-p, SR experiments [3] and has now been established. The ( -/0) energy level of Hassociated with HT and H&z according to JHVhas been deduced to be exactly midgap on the basis of the measurement of capacitance transients which JHV observe after shining light on hydrogenated, phosphorous-doped samples. The following is assumed. (a) Under illumination, at room temperature, in a depleted region, the neutral [P,H] pair captures two holes, forming H+ and P . (b) After flooding the depleted region with electrons, H+ captures two electrons and forms H . (c) A spontaneous conversion of H to H+ then occurs by emission of two electrons. To be more specific, it is assumed that "if the system makes a transition from H to H, it will coast downhill to the global minimum at BC. '* (d) The position of the acceptor level is obtained via JHV*s Eq. (4) from measurements of the electron capture time 7. , from capacitance transients.We would like to point to the following inconsistencies.(1) Despite repeated attempts by two of us (C. H. S. and R. A. A. ), the capacitance transients reported by JHV have not been seen. These transients are the key to their claim that H+ is mobile and swept out of the depletion region after illumination, and that H is produced by electron capture after debonding.Our experiments [4] included measurements on Pand As-doped Si, with Pd and Pt Schottky metallizations.(2) The assumption that under illumination all or most (P,H] pairs break up into a mobile H (and a P+) is not supported by experiment.As has been reported in an earlier study [5], the donor reactivation reaction is 30 -80% reversible.This reversibility has also been observed for all the samples tested when trying to reproduce the reported transients.We previously suggested [6,7] that [P,H] pairs may convert to a charged [P,H) defect or that H debonds from P and is trapped at a nearby (unidentified) site that becomes positively charged. Thus, the electron emission and capture processes reported by JHV do not necessarily involve monatomic interstitial hydrogen.(3) The assumption that only three states of H are present, H (at the T site), H (at the BC site), and H+ (at the BC site), is incorrect. With the exception of one study [8], there is agreement among theorists [9] that H is metastable in Si. p, SR experiments show that two paramagnetic centers coexist. One corresponds to a neutral muonium atom on the average at the T site (Mur).The other is stable, has trigonal symmetry, and is at the BC site (Munc). Both centers survive in doped samples, and recent experiments [3] show that in n-type Si the Mu...