Weight loss goals among African-American women with type 2 diabetes in a behavioral weight control program

African‐American women with type 2 diabetes experience limited weight loss in behavioral weight control programs. Some research suggests that overly ambitious weight loss expectations may negatively affect weight losses achieved but it is unknown whether they affect weight loss among African‐American women. The current study examined personal weight loss goals and expected satisfaction with a reasonable weight loss among African‐American women with type 2 diabetes starting a behavioral obesity treatment. We also explored associations among these factors and weight loss treatment outcomes. Self‐identified African‐American women (N = 84) in a 24‐session group program were assessed at baseline and 6‐month follow‐up. At baseline, women indicated weight loss goals of 14.1 ± 6.6 kg (14% of initial weight). They also reported relatively high expected satisfaction with a reasonable weight loss (7–10%). On average, participants lost 3.0 ± 3.9 kg (3% of initial weight) and attended 73 ± 21% of group sessions. Neither weight loss goals nor expected satisfaction with a reasonable weight loss was correlated with either actual weight loss outcome or attendance. Having higher personal weight loss goals was associated with lower expectations of satisfaction with a reasonable weight loss. This suggests that African‐American women with type 2 diabetes enter treatment hoping to lose far more weight than they are likely to achieve. It is important to understand the psychosocial sequelae of failing to reach these goals on subsequent weight maintenance and future weight loss attempts within this population.     

Mechanistic studies of new oximes reactivators of human butyryl cholinesterase inhibited by cyclosarin and sarin

Butyryl cholinesterase (BChE) has been seen as a key enzyme in the search for new strategies in the treatment of poisoning by organophosphates (OPs), since human BChE (HssBChE), complexed with the appropriate oxime, can be a suitable scavenger and deactivator for OPs in the blood stream. However, the efficacy of HssBChE is limited by its strict stoichiometric scavenging, slow reactivation, and propensity for aging. The improvement of the reactivation rate by new and more efficient oximes could contribute to mitigate this problem and increase the HssBChE efficiency as scavenger. Several oximes have been synthesized and tested with this goal, some with promising results, but the mechanistic aspects of the reactivation reaction are not fully understood yet. In order to better investigate this mechanism, docking and mixed quantum and molecular mechanics combined with principal components analysis were performed here to evaluate the capacity of reactivation and determine the preferred route for the reactivation reaction of two new oximes on HssBChE inhibited by the neurotoxic agents cyclosarin and sarin. Plots of potential energies were calculated and all the transition states of the reactional mechanism were determined. Our results showed a good correlation with experimental data and pointed to the most efficient oxime with both OPs. The protocol used could be a suitable tool for a preliminary evaluation of the HssBChE reactivation rates by new oximes.     

Brassinin oxidase, a fungal detoxifying enzyme to overcome a plant defense -- purification, characterization and inhibition

Blackleg fungi [Leptosphaeria maculans (asexual stage Phoma lingam) and Leptosphaeria biglobosa] are devastating plant pathogens with well-established stratagems to invade crucifers, including the production of enzymes that detoxify plant defenses such as phytoalexins. The significant roles of brassinin, both as a potent crucifer phytoalexin and a biosynthetic precursor of several other plant defenses, make it critical to plant fitness. Brassinin oxidase, a detoxifying enzyme produced by L. maculans both in vitro and in planta, catalyzes the detoxification of brassinin by the unusual oxidative transformation of a dithiocarbamate to an aldehyde. Purified brassinin oxidase has an apparent molecular mass of 57 kDa, is approximately 20% glycosylated, and accepts a wide range of cofactors, including quinones and flavins. Purified brassinin oxidase was used to screen a library of brassinin analogues and crucifer phytoalexins for potential inhibitory activity. Unexpectedly, it was determined that the crucifer phytoalexins camalexin and cyclobrassinin are competitive inhibitors of brassinin oxidase. This discovery suggests that camalexin could protect crucifers from attacks by L. maculans because camalexin is not metabolized by this pathogen and is a strong mycelial growth inhibitor.     

Central chemoreflex sensitivity and sympathetic neural outflow in elite breath-hold divers.

Repeated hypoxemia in obstructive sleep apnea patients increases sympathetic activity, thereby promoting arterial hypertension. Elite breath-holding divers are exposed to similar apneic episodes and hypoxemia. We hypothesized that trained divers would have increased resting sympathetic activity and blood pressure, as well as an excessive sympathetic nervous system response to hypercapnia. We recruited 11 experienced divers and 9 control subjects. During the diving season preceding the study, divers participated in 7.3 +/- 1.2 diving fish-catching competitions and 76.4 +/- 14.6 apnea training sessions with the last apnea 3-5 days before testing. We monitored beat-by-beat blood pressure, heart rate, femoral artery blood flow, respiration, end-tidal CO(2), and muscle sympathetic nerve activity (MSNA). After a baseline period, subjects began to rebreathe a hyperoxic gas mixture to raise end-tidal CO(2) to 60 Torr. Baseline MSNA frequency was 31 +/- 11 bursts/min in divers and 33 +/- 13 bursts/min in control subjects. Total MSNA activity was 1.8 +/- 1.5 AU/min in divers and 1.8 +/- 1.3 AU/min in control subjects. Arterial oxygen saturation did not change during rebreathing, whereas end-tidal CO(2) increased continuously. The slope of the hypercapnic ventilatory and MSNA response was similar in both groups. We conclude that repeated bouts of hypoxemia in elite, healthy breath-holding divers do not lead to sustained sympathetic activation or arterial hypertension. Repeated episodes of hypoxemia may not be sufficient to drive an increase in resting sympathetic activity in the absence of additional comorbidities.     

Aminoethyl-substituted indole-3-acetic acids for the preparation of tagged and carrier-linked auxin

Indole-3-acetic acid is an indispensable hormone (auxin) in plants and an important metabolite in humans, animals, and microorganisms. Here we introduce its 5- and 6-(2-aminoethyl)-derivatives for use in the design of novel research tools, such as immobilized and carrier-linked forms of indole-3-acetic acid and its conjugates with biochemical tags or biocompatible molecular probes. The aliphatic nitrogens of 5- and 6-(2-aminoethyl)indole were acetylated and the products were converted to the corresponding 3-(N,N-dimethylamino)methyl derivatives (gramines). These were reacted with cyanide. Saponification of the resulting acetonitriles was accompanied by N-deprotection to yield 5- and 6-(2-aminoethyl)indole-3-acetic acids. The latter were chemically stable and could be linked, via their amino groups, and without prior protection of their carboxyl moieties, to bovine serum albumin and to biotin, including appropriate spacer modules. One of the protein conjugates was used to elicit the formation of monoclonal antibodies, which were evaluated using the biotin conjugates in an enzyme-linked immunosorbent assay employing streptavidin-coupled alkaline phosphatase, and thus shown to recognize predominantly the indole-3-acetic acid moiety.     

Nuclear exclusion of the androgen receptor by melatonin

Androgen receptors (AR) play a crucial role in androgen-mediated processes and prostate cancer progression. The pineal hormone melatonin attenuates the androgen-dependent growth of benign and cancer prostate epithelial cells in vitro and may reverse clinical resistance to androgen ablation therapy in patients progressing on gonadotropin releasing hormone (GnRH) analogue. Where along the AR cascade does melatonin act remains to be determined. The effects of melatonin on AR localization, level and activity were assessed using androgen-insensitive prostate carcinoma PC3 cells stably transfected with a wild-type AR-expressing vector (PC3-AR).AR was localized to the PC3-AR cell nucleus in the absence of dihydrotestosterone (DHT). Melatonin caused a robust exclusion of the AR from the cell nucleus to the cytoplasm. The nuclear export inhibitor, leptomycin B prevented this process. The exclusion was selective since melatonin had no such effect on the nuclear localization of estrogen receptors alpha (ERalpha) in these cells.Melatonin also caused nuclear exclusion of the AR in the presence of DHT. In addition, it attenuated androgen induced reporter gene activity in PC3 cells co-transfected with the human AR and AR reporter plasmids. Elevated androgen concentrations counteracted melatonin's effects. Melatonin did not decrease AR level or androgen binding in the cells.The nuclear localization of the AR is a hallmark of its cellular activity. These data point to AR nuclear exclusion as a possible mechanism to attenuate androgen responses in target tissues.     

Control of EpsE, the phosphoglycosyltransferase initiating exopolysaccharide synthesis in Streptococcus thermophilus, by EpsD tyrosine kinase

We studied the roles of Streptococcus thermophilus phosphogalactosyltransferase (EpsE) (the priming enzyme), tyrosine kinase (EpsD), phosphatase (EpsB), and a membrane-associated protein with no known biochemical function (EpsC) in exopolysaccharide (EPS) synthesis. These proteins are well-conserved among bacteria and are usually encoded by clustered genes. Exopolysaccharide synthesis took place in the wild-type strain and a mutant lacking EpsB but not in mutants lacking EpsC, EpsD, or EpsE. The three mutants unable to synthesize EPS lacked the EpsE phosphogalactosyltransferase activity, while the two EPS-synthesizing strains possessed this activity, showing that EpsC and EpsD are required for EpsE function. An EpsD phosphorylated form was found in all strains except the epsC mutant, indicating that EpsC is necessary for EpsD phosphorylation. Moreover, the phosphorylated form of EpsD, a supposedly cytoplasmic protein, was found to be associated with the plasma membrane, possibly due to interaction with EpsC. Finally, the EpsD and EpsE elution profiles in a gel filtration chromatography assay were similar, suggesting that these two proteins colocalize in the membrane. Mutation of Tyr200, predicted to be a phosphorylation site and present in a conserved motif in bacterial phosphoglycosyltransferases, led to EpsE inactivation. In contrast, mutation of Tyr162 or Tyr199 had no effect. Taken together, these data show that EpsD controls EpsE activity. Possible mechanisms for this control are discussed.     

Incorporating diffuse photosynthetically active radiation in a single-leaf model of canopy photosynthesis for a 56-year-old Douglas-fir forest

A simple top-down model of canopy photosynthesis (P) was developed and tested in this study. The model (referred to as the Q_e-MM model) is P = αQ _e P _max/(αQ _e + P _max), α and P _max are quantum-use efficiency and potential P, respectively. Q _e is given by Q _{d 0} + kQ _{b 0}, where Q _{d 0} and Q _{b 0} are the diffuse and direct photosynthetically active radiation (PAR) incident on the canopy, respectively. Q _e can be considered to be the effective incident PAR contributing to P and k is a measure of the contribution of Q _{b 0} to Q _e. When k = 1, the Q_e-MM model becomes the regular Michaelis-Menten type model of P (referred to as the MM model). A major objective of this study was to determine how well the Q_e-MM model could estimate P of a 56-year-old coastal Douglas-fir stand. To this end, we parameterized the Q_e-MM model using five and half years of eddy-covariance measurements of CO₂ flux above the Douglas-fir stand. The Q_e-MM model, with the incorporation of a function of air temperature, accounted for 74% of the variance in over 34,000 half-hourly P measurements. P estimated using the Q_e-MM model had no systematic errors with respect to Q _{d 0}. Although the Q_e-MM model has only one more parameter than the MM model, it accounted for 30% more variance in P than the latter when total incident PAR exceeded 900 μmol m⁻² s⁻¹. On average, k was found to be 0.22. We show that this small value of k reflects the significant effect of the scattering of the solar beam and the fraction of light-limited sunlit leaves. We also show that the success of the Q_e-MM model was due to the fact that a large fraction of the sunlit leaves were light-limited as a result of their orientation to the solar beam.     

Exercise attenuates {alpha}-adrenergic-receptor responsiveness in skeletal muscle vasculature

Attenuation of sympathetic vasoconstriction(sympatholysis) in working muscles during dynamic exercise iscontroversial. A potential mechanism is a reduction in-adrenergic-receptor responsiveness. The purpose of this study wasto examine ₁- and ₂-adrenergic-receptor-mediated vasoconstriction inresting and exercising skeletal muscle using intra-arterial infusionsof selective agonists. Thirteen mongrel dogs were instrumentedchronically with flow probes on the external iliac arteries of bothhindlimbs and a catheter in one femoral artery. The selective₁-adrenergic agonist (phenylephrine) or the selective₂-adrenergic agonist (clonidine) was infused as a bolusinto the femoral artery catheter at rest and during mild and heavyexercise. Intra-arterial infusions of phenylephrine elicited reductionsin vascular conductance of 76 ± 4, 71 ± 5, and 31 ± 2% at rest, 3 miles/h, and 6 miles/h and 10% grade, respectively.Intra-arterial clonidine reduced vascular conductance by 81 ± 5, 49 ± 4, and 14 ± 2%, respectively. The response tointra-arterial infusion of clonidine was unaffected by surgicalsympathetic denervation. Agonist infusion did not affect eithersystemic blood pressure, heart rate, or blood flow in the contralateraliliac artery. ₁-Adrenergic-receptor responsiveness wasattenuated during heavy exercise. In contrast,₂-adrenergic-receptor responsiveness was attenuated evenat a mild exercise intensity. These results suggest that the mechanismof exercise sympatholysis may involve reductions in postsynaptic-adrenergic-receptor responsiveness.