A role for glucose and insulin preprandial profiles to differentiate meals and snacks

A physiological distinction between eating occasions may help account for contradictory findings on the role of eating frequency in energy homeostasis. We assessed this issue using a midafternoon eating occasion known in France as the goûter that often consists of snack foods. Among the 24 male subjects, 8 habitually consumed four meals per day, i.e., were usual goûter eaters (GE) and 16 habitually took 3 meals per day, i.e., usual non-goûter non-snack eaters (NGNSE). All subjects were time blinded from lunchtime and had to request subsequent meals. Blood was continuously withdrawn and collected with a change of tube every 10 min until dinner request. During the session, 8 of the non-goûter eaters (NGE) were offered a snack 210 min after lunch and were designated as non-goûter snack eaters (NGSE) if they ate. Results showed that the goûter was preceded by high hunger scores and a linear decline in plasma glucose (−9.0±3.0%, P<.05) and insulin concentrations (−22.9±6.0%, P<.05). These profiles were not observed before the snack. The dinner of GE was requested later and was smaller compared to NGNSE, whereas the snack altered neither time of request nor energy intake (EI) at dinner. Among blood variables, leptin at the onset of eating was the only factor that was predictive of both intermeal interval and EI. The glucose and insulin profiles indicate that snacks should not be considered as meals in studies on the role of eating frequency in energy homeostasis.     

Cartilage engineering from ovine umbilical cord blood mesenchymal progenitor cells

We aimed to determine whether three-dimensional (3D) cartilage could be engineered from umbilical cord blood (CB) cells and compare it with both engineered fetal cartilage and native tissue. Ovine mesenchymal progenitor cells were isolated from CB samples (n=4) harvested at 80-120 days of gestation by low-density fractionation, expanded, and seeded onto polyglycolic acid scaffolds. Constructs (n=28) were maintained in a rotating bioreactor with serum-free medium supplemented with transforming growth factor-beta1 for 4-12 weeks. Similar constructs seeded with fetal chondrocytes (n=13) were cultured in parallel for 8 weeks. All specimens were analyzed and compared with native fetal cartilage samples (n=10). Statistical analysis was by analysis of variance and Student's t-test (p<.01). At 12 weeks, CB constructs exhibited chondrogenic differentiation by both standard and matrix-specific staining. In the CB constructs, there was a significant time-dependent increase in extracellular matrix levels of glycosaminoglycans (GAGs) and type-II collagen (C-II) but not of elastin (EL). Fetal chondrocyte and CB constructs had similar GAG and C-II contents, but CB constructs had less EL. Compared with both hyaline and elastic native fetal cartilage, C-II and EL levels were, respectively, similar and lower in the CB constructs, which had correspondingly lower and similar GAG levels than native hyaline and elastic fetal cartilage. We conclude that CB mesenchymal progenitor cells can be successfully used for the engineering of 3D cartilaginous tissue in vitro, displaying select histological and functional properties of both native and engineered fetal cartilage. Cartilage engineered from CB may prove useful for the treatment of select congenital anomalies.     

Interaction of adenosine and its phosphorylated derivatives with putative purinergic receptors in the gill vascular bed of rainbow trout

1. The haemodynamic responses of trout gill to pulses of adenosine and related nucleotides were recorded in isolated trout head preparations. 2. Pulses of adenosine and related nucleotides induced a vasoconstriction of arterial gill vessels. Theophylline antagonized the resonse to adenosine but had not influence on its metabolism. 3. Dipyridamole and two adenosine deaminase inhibitors [deoxycoformycin and erythro-9(2-hydroxy-3-nonyl) adenine] had no effect on either the haemodynamic response of adenosine or its deamination and its uptake by gill tissues. 4. The adenosine response was neither mediated by cholinergic nor adrenergic receptors. 5. These results suggest the existence of extracellular "purinergic receptors" in the gills of trout.     

Genotypic characteristics of two serotypes of Bartonella henselae

The study of 16S rRNA gene sequences of all isolates of Bartonella henselae obtained in our laboratory and others from human patients or cats has revealed two genotypes according to the sequence of the 16S rRNA gene. Two isolates of these genotypes have previously been related to two different serotypes, and lack of cross-protection of the two serotypes has been demonstrated in cats. We investigated the grouping of eight strains of B. henselae on the basis of 16S ribosomal DNA, 35-kDa protein, Pap 31 protein, and internal transcribed spacer (ITS) gene sequencing; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles; and monoclonal antibody reactivity studies. Houston-1, 90-615, and SA2 strains showed the same patterns in SDS-PAGE, but they differed from the patterns of B. henselae isolates URBHLLY8, URBHLIE9, Cat6, Fizz, and CAL-1. Nine monoclonal antibodies derived from BALB/c mice immunized with B. henselae Houston-1 strain reacted only with strains Houston-1, 90-615, and SA2, and not with any other Bartonella strains. The two serogroups corresponded with two genotypes based on differences in the sequences of the genes encoding 16S rRNA, 35-kDa protein, and Pap 31 protein. Sequences of ITS genes were highly divergent among strains, as each had a unique sequence and the subdivision was not supported by DNA-DNA relatedness study. Study of 22 additional strains of B. henselae isolated from French bacteremic cats demonstrated that they all belong to one or the other of the proposed serotype or genotype.     

Two large French pedigrees with non syndromic sensorineural deafness and the mitochondrial DNA T7511C mutation: evidence for a modulatory factor

Hearing impairment is the most frequent sensory defect in children, with a genetic basis in about 50% of cases. Several point mutations and deletions in mitochondrial DNA (mtDNA) have been identified in non-syndromic sensorineural hearing loss (NSSNHL). Beside the frequent A1555G mutation, a number of mutations in tRNAs have been reported recently, but their incidence remains unknown. We identified the T7511C mutation in the tRNASer(UCN) gene in two French families with isolated deafness. Maternal transmission was obvious in both. The 15 patients with hearing impairment exhibited a variable disease phenotype in terms of onset, severity, and progression. T7511C was present in all the patients screened. Homoplasmic and heteroplasmic levels were observed and did not correlate with the severity of the disease. T7511C was also present in 12 hearing offspring of the oldest deaf mothers, confirming the existence of modulatory factors. Our data suggest that this mtDNA mutation should be screened for in all cases of familial NSSNHL compatible with maternal transmission.     

Functional interactions between the VRP1–LAS17 and RHO3–RHO4 genes involved in actin cytoskeleton organization in Saccharomyces cerevisiae

The RGD1 gene from Saccharomyces cerevisiae, which encodes a GTPase-activating protein for the Rho3 and Rho4 small G proteins, exhibits synthetic lethality with the VRP1 and LAS17 genes. Their products are proline-rich proteins that interact with both actin and myosins to ensure polarized growth. By testing functional links, we found that the VRP1 and LAS17 genes are potent suppressors of the rho3Delta mutation. In particular, they restore the polarization of actin patches in rho3Delta cells. Moreover, the vrp1Delta and las17Delta mutations were found to display a similar pattern of genetic interactions with specific actin-linked genes. These mutations also increase the sensitivity to activated forms of both Rho3p and Rho4p. These data support our working model, in which the VRP1 and LAS17 genes define a cellular complex that works in concert with the RHO3-RHO4 signaling pathway in yeast polarized growth. In addition, other observations lead us to propose that Rvs167p may act as a linking protein between the two cellular elements.     

Immune status and uptake of antiretroviral interventions to prevent mother-to-child transmission of HIV-1 in Africa

The aim of this study performed in Abidjan, C?te d'Ivoire, was to describe the distribution of CD4+ T-cell lymphocytes (CD4) in HIV-1-infected (HIV+) pregnant women diagnosed during prenatal voluntary counseling and testing and to assess whether HIV-related immunodeficiency influenced the acceptance of an antiretroviral (ARV) package (zidovudine beginning at 36 weeks of amenorrhea plus intrapartum nevirapine) to prevent mother-to-child transmission. Between April and June 2002, a CD4 count was systematically performed in all HIV+ women (n=221) in 5 antenatal clinics carrying out voluntary counseling and testing. No difference in CD4 count was found in HIV+ women who did not return for their test result (n=50) and those who were informed of their positive serostatus (n=171) (median CD4 count: 389/mm3 vs. 420/mm3; P=0.19). We also found a lack of difference in CD4 count in those who accepted ARV (n=72) and those who did not but knew their HIV status (n=99) (median CD4 count: 405/mm3 vs. 425/mm3; P=0.47). The overall uptake of the intervention (31.9%) appeared to be independent of the maternal immune status.     

Ovarian senescence in the rhesus monkey (Macaca mulatta)

BACKGROUND: A decline in fertility is evident in human females past their middle thirties. This 'reproductive senescence', marked by a sharp decline in pregnancy rates, may be attributed to reductions in numbers of available oocytes and their quality. Because Old World primates exhibit ovarian morphology and physiological control and timing of menstrual cycles closely resembling those of humans, the current study investigated the rhesus macaque as a potential model for human reproductive senescence. METHODS: Ovaries collected from females aged 1-25 years and divided into five age groups were analysed histologically. RESULTS: General ovarian morphology demonstrated significant changes as the females approached menopause. The proportions of primordial and primary follicles all demonstrated significant differences across age groups (primordial: 77.1, 79.9, 69.7, 62.9, 55.1%; primary: 21.5, 18.8, 28.5, 35.2, 43.1% for age groups 1 to 5 respectively; P<0.0001 for both). Samples from females approaching or undergoing the menopausal transition (aged 20-25 years) demonstrated evidence of ovarian senescence, having scattered and atretic follicles, low numbers of primordial follicles and reduced stromal tissue. CONCLUSION: This study supports the value of the rhesus monkey as a model for reproductive ageing because its ovary undergoes follicular reservoir depletion similar to that seen in humans.     

Different sympathovagal modulation of heart rate during social and nonsocial stress episodes in wild-type rats

The acute consequences of a social aversive stimulus (defeat) on the autonomic control upon the electrical activity of the heart were measured and compared to those observed in three nonsocial stress paradigms, namely restraint, shock-probe test, and swimming. Electrocardiograms were recorded from rats via radiotelemetry, and the autonomic neural control of the heart was evaluated via measures of heart rate and heart rate variability, such as the average R-R interval (RR), the standard deviation of RR (SD), the coefficient of variance (SD/RR), and the root-mean-square of successive R-R interval differences (r-MSSD). Although all stressors induced significant reductions of average R-R interval, the effect of defeat was significantly larger (p < 0.05). The social stimulus also determined a significant decrease in the variability indexes (p < 0.01 for all), whereas in the other stress conditions they were either unchanged or increased (SD/RR during restraint, p < 0.05; SD and SD/RR during swimming, p < 0.05 and p < 0.01). Cardiac arrhythmias (mostly ventricular premature beats, VPBs) were far more frequent during defeat than during the other challenging situations (p < 0.01), with an average of 33.5 +/- 6.5 VPBs per 15-min test recording. These data suggest that during defeat autonomic control was shifted toward a sympathetic dominance, whereas in rats exposed to nonsocial stressors, although significant heart rate accelerations were also found, sympathovagal balance was substantially maintained. These differences in autonomic stress responsivity explain the different susceptibility to ventricular arrhythmias and indicate that a social challenge can be far more detrimental for cardiac electrical stability than other nonsocial aversive stimuli.