Hannah Kanety

The acute effect of various glycemic index dietary carbohydrates on endothelial function in nondiabetic overweight and obese subjects.

OBJECTIVES This study sought to explore the effect of glycemic-index dietary carbohydrates on endothelium-dependent flow-mediated dilation (FMD) in overweight and obese nondiabetic volunteers. BACKGROUND Post-prandial hyperglycemia has been recognized as a cardiovascular risk factor in both the diabetic and the general population. Endothelial dysfunction has been shown to occur in diabetic and hyperglycemic patients. METHODS We prospectively assessed brachial artery FMD in 56 healthy overweight and obese nondiabetic volunteers (38 [67.9%] men, mean age 48 +/- 6 years) on 4 separate mornings, 1 to 2 weeks apart. After overnight fasting, the percent FMD (%FMD) improvement and endothelium-independent nitroglycerin-mediated dilation (%NTG) were assessed, after which subjects received 1 of 4 group meals at each visit (placebo [water] or a carbohydrate meal of glucose, cornflakes, or high-fiber cereal). Meals were distributed in a rotating randomized fashion, such that each subject received all 4 meals once throughout the study period. RESULTS Fasting and 2-h post-prandial serum glucose levels were similar in all 3 meals, whereas at 30 to 90 min, serum glucose levels were significantly higher after glucose and cornflakes (high glycemic) compared with fiber (low glycemic). Baseline %FMD, not significantly different in the 3 carbohydrate-based meals, was reduced 2 h post-prandially in all groups, showing statistical significance in only high-glycemic index meals: glucose (15 +/- 9% vs. 10 +/- 8%, p < 0.01), cornflakes (13 +/- 7% vs. 9 +/- 7%, p < 0.01). No correlation was observed between the %FMD reduction rate and glucose levels throughout the study period. CONCLUSIONS High- compared with low-glycemic carbohydrate consumption significantly suppresses FMD in nondiabetic overweight and obese volunteers, suggesting a mechanism whereby high-glycemic meals may enhance cardiovascular risk.

Adiponectin and Leptin Concentrations in Dichorionic Twins with Discordant and Concordant Growth

CONTEXT Discordant twin gestation, in which one fetus is growth restricted, is a unique model that can elucidate the mechanism(s) by which the intrauterine environment affects fetal growth. OBJECTIVE The objective of the study was to determine the cord blood adiponectin and leptin concentrations and evaluate their association with birth weight in dichorionic twins, with and without growth discordance. DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME MEASURE: In this cross-sectional study, arterial cord blood adiponectin and leptin concentrations were determined in two groups of newborns: 1) discordant twins, in which one of the twins is growth restricted (small for gestation age and abnormal umbilical arteries Doppler) and the other is appropriate for gestation age (AGA) (n = 14 pairs); and 2) concordant twins, in which both twins are AGA (n = 15 pairs). RESULTS Results were: 1) within the discordant twins group, the median adiponectin concentration was significantly lower in the growth-restricted newborns than in their cotwins (P = 0.004); 2) within the concordant twin group, there was no significant difference in the median cord blood adiponectin concentration between the two AGA twins; 3) the median leptin concentration did not differ between the twins pairs in both study groups; 4) a positive correlation between cord blood adiponectin concentrations and both birth weight (r = 0.7, P < 0.001) and gestational age (r = 0.6, P < 0.02) was found only in the small-for-gestational-age newborns; 5) linear regression model revealed that birth weight is independently associated with circulating adiponectin concentration. CONCLUSIONS Low circulating adiponectin concentrations, previously reported in adults, children, and infants who were born small for gestational age, characterize fetuses with growth restriction and are independently associated with birth weight.

Intramolecular donor-acceptor systems: Part 8. Solvent and substituent effects on the fluorescence emission of 6-N-methyl-N-phenylamino-2-naphthalenesulfon-N,N-dimethylamides

Abstract The dual fluorescence (emissions from S 1,np and S 1,ct states) of N -phenylaminonaph-thalenesulfonate (ANS) systems is briefly reviewed. The 6- N -methyl- N -phenylamino-2-naphthalenesulfon- N , N -dimethylamides also exhibit dual fluorescence, as shown by plots of emission energy and Φ F against the solvent polarity parameter, E T (30). The solvent polarities, for which appearance of S 1,ct emission marks the occurrence of an intramolecular electron transfer (i.e.t.) process, are appreciably lower than those of the corresponding sulfonates. The fluorescence of the dimethylamides exhibits a high sensitivity to substituent change, the apparent Hammett ϱ value being ca. −13 for unsubstituted dimethylamide and −33 for N -methyl-substituted dimethylamide. The N , N -dimethylamides are particularly suitable for the investigation of the rates and mechanisms of intramolecular electron-transfer processes by picosecond and nanosecond pulse techniques.

Adiponectin levels in adolescent girls with polycystic ovary syndrome (PCOS)

Objective  To determine serum adiponectin concentrations in adolescent girls with and without polycystic ovary syndrome (PCOS) and to assess possible correlations of adiponectin levels with insulin and androgen levels.

Kinetic studies on intramolecular electron transfer in solution

Abstract Lifetimes of the non-planar S 1 (S 1,np ) state of 6-N-4-methylphenylamino-2-naphthalenesultonic acid N,N-dimethylamide (TNSDMA), produced by picosecond pulse excitation, are the same as the risetimes of the charge-transfer S 1 (S 1,ct ) state, which itself decays at lower rates, in a series of linear alkanol solvents. Factors which influence the electron-transfer rates are noted.

RNA-Binding Protein PTB and MicroRNA-221 Coregulate AdipoR1 Translation and Adiponectin Signaling

Adiponectin receptor 1 (AdipoR1) mediates adiponectin’s pleiotropic effects in muscle and liver and plays an important role in the regulation of insulin resistance and diabetes. Here, we demonstrate a pivotal role for microRNA-221 (miR-221) and the RNA-binding protein polypyrimidine tract–binding protein (PTB) in posttranscriptional regulation of AdipoR1 during muscle differentiation and in obesity. RNA-immunoprecipitation and luciferase reporter assays illustrated that both PTB and miR-221 bind AdipoR1-3′UTR and cooperatively inhibit AdipoR1 translation. Depletion of PTB or miR-221 increased, while overexpression of these factors decreased, AdipoR1 protein synthesis in both muscle and liver cells. During myogenesis, downregulation of PTB and miR-221 robustly induced AdipoR1 translation, providing a mechanism for enhanced AdipoR1 protein expression and activation in differentiated muscle cells. In addition, since both PTB and miR-221 are upregulated in liver and muscle of genetic and dietary mouse models of obesity, this novel translational mechanism may be at least partly responsible for the reduction in AdipoR1 protein levels in obesity. These findings highlight the importance of translational control in regulating AdipoR1 protein expression and adiponectin signaling. Given that adiponectin is reduced in obesity, induction of AdipoR1 could potentially enhance adiponectin beneficial effects and ameliorate insulin resistance and diabetes.

Chemerin is present in human cord blood and is positively correlated with birthweight

OBJECTIVE Chemerin, a novel adipokine, has been implicated in adipogenesis, inflammation, and metabolism. The aims of this study were to determine the presence of chemerin in cord blood and its association with birthweight. STUDY DESIGN This cross-sectional study included the following: (1) twins with (n = 24) or without (n = 28) birthweight discordancy; and (2) singletons subclassified into small-for-gestational-age (SGA; n = 18); appropriate for gestational age (AGA; n = 33); and large-for-gestational-age (LGA; n = 8). Cord blood chemerin was determined. Parametric and nonparametric statistics were used for analysis. RESULTS The results of the study included the following: (1) within the discordant twins group, the median chemerin concentration was significantly lower in the SGA group than in their cotwins; (2) within singletons, the median chemerin concentration was significantly higher in the LGA than the AGA newborns; and (3) the regression model revealed that chemerin was independently associated with birthweight. CONCLUSION Cord blood chemerin is present in cord blood and its concentrations are positively correlated with birthweight. These novel findings support a role of adipokines in fetal growth.

Picosecond spectroscopic measurement of very fast intersystem crossing for 9,10-dioxa-anti-bimanes

Abstract Picosecond spectroscopy, following the buildup of T1 → Tn absorption (maximum at 420 nm), shows that the T1 state of 1,5-diazabicyclo[3,3,0]octa-3,7-diene-2,6-diones(9,10-dioxa-anti-bimanes) is formed within about 10 ps. The nature of the T1 state was confirmed by decay rates of T1 → Tn absorption in acetonitrile (n = 0.375 cP, knr = 4.5 × 105 s−1), 1,2-ethanediol (n = 26 cP, knr = 1.5 × 104 s−1 and glycerol (n = 1400 cP, knr = 1.3 × 103 s−1). The very fast intersystem crossing is ascribed to the proximity of a 3nπ* state to the ππ* (S1 state produced by light absorption (El-Sayed rule).

Expression and regulation of sFRP family members in human granulosa cells

Follicular development and ovulation are major processes in the reproductive system. Understanding their complexity is important to female fertility treatments and the control of reproductive processes. Wnt signaling pathway components were shown to be involved in reproduction in animal models. The secreted frizzled-related protein-4 (sFRP4), a potential modulator of Wnt4 signaling pathway, was shown to be induced by LH in rodents and expressed in the corpus lutea, but the pattern of its expression in human ovaries remains unknown. We evaluated the expression pattern of sFRP4 and other sFRP family members in human mural and cumulus granulosa cells (GCs), as well as their regulation by LH/hCG. GCs were obtained from follicles aspirated during in vitro maturation and IVF procedures. GCs were also plated and grown in culture. We showed that the human sFRP4 expression decreases as follicles grows to the preovulatory stage and its expression was higher in cumulus GCs than in mural GCs. Interestingly, LH/hCG stimulation of GCs in vivo and in culture resulted in decreased expression of sFRP4. Of the other sFRP family members, sFRP5 expression was found in mural and cumulus GC in vivo and was shown to be induced by LH/hCG in vitro and in vivo. In summary, sFRP4 is expressed in human GCs and its expression declines during late antral follicular growth. sFRP4 expression is also inhibited by LH/hCG, unlike its rodent homolog. In human GC, sFRP5 may substitute the role of sFRP4 in mouse GC.

Kinetics and mechanism of intramolecular electron transfer in solution

The picosecond pulse generated S1,np state of 6-N-4-methylphenylamino-2-naphthalenesulphonic acid NN-dimethylamide (TNSDMA) decays by intramolecular electron transfer (i.e.t) faster than the appearance of the product, an equilibrium mixture of the charge-transfer, S1,ct, and S1,np states (temperature-independent ratio of 4–5), which decays at ca. 0.1 of the rate for the S1,np state. In propan-1-ol, rates of “fast” i.e.t. processes vary with solvent cluster motion (1/τ1, lowest dielectric relaxation rate) over a wide range of temperatures with log k linear in ⅔ log (1/η). Up to ca. –15 °C, “slow” i.e.t. processes probably vary in the same way, but at higher temperatures they are controlled by local group motion (1/τ2, second lowest dielectric relaxation rate). A molecular model for the S1,ct-state–methanol complex is presented.