Contribution of glucose tolerance and plasma insulin levels to the relationships between body fat distribution and plasma lipoprotein levels in women.

Numerous interrelated metabolic and morphological variables such as plasma insulin levels, glucose tolerance and abdominal obesity are associated with changes in plasma lipoprotein levels. The present study was undertaken to differentiate, using a multivariate approach, the respective contributions of plasma glucose and insulin levels, obesity and regional adipose tissue distribution to the variance in plasma lipoproteins. The study group was composed of 69 healthy premenopausal women (age 35.4 +/- 5.0 years (mean +/- s.d.); percent body fat 40.7 +/- 10.1). Indices of carbohydrate metabolism showed significant univariate correlations with triglyceride (TG) and/or cholesterol (CHOL) content of plasma VLDL, LDL and HDL (P less than 0.05). Multivariate analyses indicated that the explained variance in plasma VLDL-TG (R2 x 100 = 44 percent, P less than 0.05) and LDL-apoprotein (apo) B levels (R2 x 100 = 33.1 percent, P less than 0.08) was entirely accounted for by indices of carbohydrate metabolism and body fat distribution, whereas total body fatness added no significant contribution to these models. Multivariate analyses also revealed that the best possible regression model to predict the variation in plasma HDL2-CHOL levels only included computed tomography-derived deep abdominal adipose tissue area (P less than 0.0001). All other variables were unable to further improve the explained variance in plasma HDL2-CHOL levels. In partial correlation analyses, indices of carbohydrate metabolism and the waist-to-hip circumference ratio (WHR) remained significantly correlated with plasma VLDL-TG and LDL-apo B levels after adjustment of VLDL-TG and LDL-apo B for either insulin and glucose levels, or for the WHR (P less than 0.08). After correcting for deep abdominal fat accumulation, no significant correlation was observed between indices of carbohydrate metabolism and plasma HDL2-CHOL levels whereas deep abdominal fat showed significant correlations with HDL2-CHOL levels (P less than 0.05) after correction for indices of carbohydrate metabolism. These results suggest that both disturbances in glucose-insulin homeostasis and abdominal obesity are significantly associated with changes in plasma VLDL-TG and LDL-apo B levels and that these associations are partly independent from each other. These results also indicate that mechanisms other than disturbances in glucose homeostasis and hyperinsulinemia are responsible for the association between the level of deep abdominal fat and plasma HDL2-CHOL levels.     

Medium term outcome for infant repair in tetralogy of Fallot: indicators for timing of surgery

Objective: To assess the impact of early corrective surgery on the short and medium term outcome in tetralogy of Fallot (TOF). Materials and methods: All patients under 12 months of age undergoing correction of isolated TOF between February 1997 and July 2003 were reviewed retrospectively. Outcome data for mortality, post-operative care management, major morbidity and clinical follow-up were analysed. Results: Fifty-two operations were performed. The mean age at surgery was 5 months (range 1–12) of whom 16 (30.8%) were less than 3 months old, including 2 neonates, 22 (42.3%) were 3–6 months old and 14 (26.9%) were 7–12 months old. There was 1 (1.9%) early death caused by a cerebro-vascular accident and 1 (1.9%) late death secondary to acute infective endocarditis. There were no differences in post-operative morbidities attributable to age. Patients under 3 months old required greater duration of post-operative ventilation, ITU stay and in-hospital stay. At a mean follow-up of 4.0 years (range 1.5–8.0), 33 (63.5%) patients had well-tolerated pulmonary regurgitation (PR) and 3 (5.8%) patients required re-operation for right ventricular outflow tract obstruction (RVOTO). All patients had right bundle-branch-block but with QRS < 150 ms. Conclusion: Early definitive repair of TOF can be performed safely on patients under 6 months old. Age at surgery does not appear to affect the medium term haemodynamic outcome. However, early surgery does escalate the need for ICU care. This data suggests repair in asymptomatic patients be delayed until 3–6 months of age.     

Microscale Transport and Sorting by Kinesin Molecular Motors

As biomolecular detection systems shrink in size, there is an increasing demand for systems that transport and position materials at micron- and nanoscale dimensions. Our goal is to combine cellular transport machinery-kinesin molecular motors and microtubules-with integrated optoelectronics into a hybrid biological/engineered microdevice that will bind, transport, and detect specific proteins, DNA/RNA molecules, viruses, or cells. For microscale transport, 1.5 microm deep channels were created with SU-8 photoresist on glass, kinesin motors adsorbed to the bottom of the channels, and the channel walls used to bend and redirect microtubules moving over the immobilized motors. Novel channel geometries were investigated as a means to redirect and sort microtubules moving in these channels. We show that DC and AC electric fields are sufficient to transport microtubules in solution, establishing an approach for redirecting microtubules moving in channels. Finally, we inverted the geometry to demonstrate that kinesins can transport gold nanowires along surface immobilized microtubules, providing a model for nanoscale directed assembly.     

The response to exercise with constant energy intake in identical twins

Seven pairs of young adult male identical twins completed a negative energy balance protocol during which they exercised on cycle ergometers twice a day, 9 out of 10 days, over a period of 93 days while being kept on a constant daily energy and nutrient intake. The total energy deficit caused by exercise above the estimated energy cost of body weight maintenance reached 244 +/- 9.8 MJ (Mean +/- SEM). Baseline energy intake was estimated over a period of 17 days preceding the negative energy balance protocol. Mean body weight loss was 5.0 kg (SEM = 0.6) (p < 0.001) and it was entirely accounted for by the loss of fat mass (p < 0.001). Fat-free mass was unchanged. Body energy losses reached 191 MJ (SEM = 24) (p < 0.001) which represented about 78% of the estimated energy deficit. Subcutaneous fat loss was slightly more pronounced on the trunk than on the limbs as estimated from skinfolds, circumferences, and computed tomograply (CT). The reduction in CT-assessed abdominal visceral fat was quite striking, from 81 cm2 (SEM = 5) to 52 cm2 (SEM = 6) (p < 0.001). At the same submaximal power output level, subjects oxidized more lipids than carbohydrates after the program as indicated by the changes in the respiratory exchange ratio (p < or = 0.05). Intrapair resemblance was observed for the changes in body weight (p < 0.05), fat mass (P < 0.01), percent fat (p < 0.01), body energy content (p < 0.01), sum of 10 skinfolds (p < 0.01), abdominal visceral fat (p < 0.01), fasting plasma triglycerides (p < 0.05) and cholesterol (p < 0.05), maximal oxygen uptake (p < 0.05), and respiratory exchange ratio during submaximal work (p < 0.01). We conclude that even though there were large individual differences in response to the negative energy balance and exercise protocol, subjects with the same genotype were more alike in responses than subjects with different genotypes particularly for body fat, body energy, and abdominal visceral fat changes. High lipid oxidizers and low lipid oxidizers during submaximal exercise were also seen despite the fact that all subjects had experienced the same exercise and nutritional conditions for about three months.     

Changes in plasma lipoprotein and apolipoprotein composition in relation to oral versus percutaneous administration of estrogen alone or in cyclic association with utrogestan in menopausal women.

Sixty-three postmenopausal women were assigned to four treatment groups and received either Premarin or percutaneous 17 beta-estradiol (Oestrogel) alone or in combination with micronized progesterone (Utrogentan). The oral administration of estrogen alone to hysterectomized women resulted in: 1) a significant increase in triglyceride levels in plasma and all major lipoprotein fractions, 2) a significant increase in very low density lipoprotein cholesterol, 3) a significant decrease in low density lipoprotein (LDL) cholesterol but not LDL apo B concentration, 4) a significant increase in all the lipid components of high density lipoprotein (HDL) as well as apo AI, 5) and a significant increase in HDL2 cholesterol. In contrast, percutaneous administration of estrogen to hysterectomized women only increased HDL2 cholesterol and the triglyceride and cholesterol content of the whole HDL fraction. These results suggest that the route of estrogen administration is important in determining effects on lipoprotein metabolism. The same two estrogens were given to women with natural menopause, along with utrogestan, a micronized progesterone. The simultaneous administration of Utrogestan reversed the HDL cholesterol elevating effect of percutaneous estrogen alone, but it had no effect on other plasma lipoproteins. On the other hand, utrogestan in combination with oral estrogen had several potential beneficial effects on plasma lipoproteins. This combination did not negate the effects of oral estrogen alone on HDL, rather it further increased the concentrations of HDL cholesterol and apo AI. It also did not negate the LDL cholesterol lowering effect of oral estrogen alone. Furthermore, utrogestan lowered the magnitude of hypertriglyceridemia induced by oral estrogen alone. These results suggest that Utrogestan has lower potency of androgenic action and has desirable effects when given in cyclic combination with estrogen.     

Correlates of plasma very-low-density lipoprotein concentration and composition in premenopausal women

Potential correlates of plasma very-low-density lipoprotein (VLDL) concentration and composition were studied in a sample of 75 premenopausal women. Fasting plasma free fatty acid (FFA) levels, as well as plasma glucose and insulin levels in the fasting state and during an oral glucose tolerance test, displayed significant positive correlations with plasma triglyceride (TG) and VLDL-TG levels (P less than .005). Plasma post-heparin lipoprotein lipase (LPL) activity, measured in a subsample of 31 women from the original sample, was negatively correlated with plasma TG, VLDL-cholesterol (CHOL), VLDL-TG, and VLDL-apolipoprotein (apo) B concentrations (.005 greater than P less than .05). Multivariate analyses showed that, after LPL was considered, the insulin area was the only other metabolic variable studied that was significantly correlated with VLDL-apo B concentration, whereas fasting FFA levels were significantly correlated with plasma TG and VLDL-TG levels. ANOVA revealed that plasma VLDL-CHOL, VLDL-TG, and VLDL-apo B levels were not associated with the glucose area, but were significantly associated with the insulin area (P less than .005). When the effect of insulin area was controlled for, the plasma FFA levels did not contribute significantly to the variance in VLDL-CHOL and VLDL-apo B, but showed an independent effect on VLDL-TG levels (P less than .05). Finally, stepwise multiple regression analyses indicated that once the variance explained by plasma LPL activity and by the insulin area was considered, no other metabolic variable could account for the variation in VLDL-CHOL and VLDL-apo B levels, whereas fasting FFA levels explained a further 5% of the VLDL-TG variance and one third of the variance observed in the VLDL-TG/apo B ratio.(ABSTRACT TRUNCATED AT 250 WORDS)     

A genetic method for dating ancient genomes provides a direct estimate of human generation interval in the last 45,000 years

The study of human evolution has been revolutionized by inferences from ancient DNA analyses. Key to these studies is the reliable estimation of the age of ancient specimens. High-resolution age estimates can often be obtained using radiocarbon dating, and, while precise and powerful, this method has some biases, making it of interest to directly use genetic data to infer a date for samples that have been sequenced. Here, we report a genetic method that uses the recombination clock. The idea is that an ancient genome has evolved less than the genomes of present-day individuals and thus has experienced fewer recombination events since the common ancestor. To implement this idea, we take advantage of the insight that all non-Africans have a common heritage of Neanderthal gene flow into their ancestors. Thus, we can estimate the date since Neanderthal admixture for present-day and ancient samples simultaneously and use the difference as a direct estimate of the ancient specimen’s age. We apply our method to date five Upper Paleolithic Eurasian genomes with radiocarbon dates between 12,000 and 45,000 y ago and show an excellent correlation of the genetic and ¹⁴C dates. By considering the slope of the correlation between the genetic dates, which are in units of generations, and the ¹⁴C dates, which are in units of years, we infer that the mean generation interval in humans over this period has been 26–30 y. Extensions of this methodology that use older shared events may be applicable for dating beyond the radiocarbon frontier.Ancient DNA analyses have transformed research into human evolutionary history, making it possible to directly observe genetic variation patterns that existed in the past, instead of having to infer them retrospectively (1). To interpret findings from an ancient specimen, it is important to have an accurate estimate of its age. The current gold standard is radiocarbon dating, which is applicable for estimating dates for samples up to 50,000 y old (2). This method is based on the principle that, when a living organism dies, the existing ¹⁴C starts decaying to ¹⁴N with a half-life of ∼5,730 y (3). By measuring the ratio of ¹⁴C to ¹²C in the sample and assuming that the starting ratio of carbon isotopes is the same everywhere in the biosphere, the age of the sample is inferred. A complication is that carbon isotope ratios vary among carbon reservoirs (e.g., marine, freshwater, atmosphere) and over time. Thus, ¹⁴C dates must be converted to calendar years using calibration curves based on other sources, including annual tree rings (dendrochronology) or uranium-series dating of coral (2). Such calibrations, however, may not fully capture the variation in atmospheric carbon. In addition, contamination of a sample by modern carbon, introduced during burial or by handling afterwards, can make a sample seem younger than it actually is (2). The problem is particularly acute for samples that antedate 30,000 y ago because they retain very little original ¹⁴C.Here, we describe a genetic approach for dating ancient samples, applicable in cases where DNA sequence data are available, as is becoming increasingly common (1). This method relies on the insight that an ancient genome has experienced fewer generations of evolution compared with the genomes of its living (i.e., extant) relatives. Because recombination occurs at an approximately constant rate per generation, the accumulated number of recombination events provides a molecular clock for the time elapsed or, in the case of an ancient sample, the number of missing generations since it ceased to evolve. This idea is referred to as “branch shortening” and estimates of missing evolution can be translated into absolute time in years by using an estimate of the mean age of reproduction (generation interval) or an independent calibration point such as human–ape divergence time.Branch shortening has been used in studies of population history, for inferring mutation rates, and for establishing time scales for phylogenic trees in humans and other species (4, 5). It was first applied for dating ancient samples on a genome-wide scale by Meyer et al. (6), who used the mutation clock (instead of the recombination clock as proposed here) to estimate the age of the Denisova finger bone, which is probably older than 50,000 y, and has not been successfully radiocarbon dated (6). Specifically, the authors compared the divergence between the Denisova and extant humans and calibrated the branch shortening relative to human–chimpanzee (HC) divergence time. The use of ape divergence time for calibration, however, relies on estimates of mutation rate that are uncertain (7). In particular, recent pedigree studies have yielded a yearly mutation rate that is approximately twofold lower than the one obtained from phylogenetic methods (7). In addition, comparison with HC divergence relies on branch-shortening estimates that are small relative to the total divergence of millions of years, so that even very low error rates in allele detection can bias estimates. These issues lead to substantial uncertainty in estimated age of the ancient samples, making this approach impractical for dating specimens that are tens of thousands of years old, a time period that encompasses the vast majority of ancient human samples sequenced to date.Given the challenges associated with the use of the mutation clock, here we explore the possibility of using a molecular clock based on the accumulation of crossover events (the recombination clock), which is measured with high precision in humans (8). In addition, instead of using a distant outgroup, such as chimpanzees, we rely on a more recent shared event that has affected both extant and ancient modern humans and is therefore a more reliable fixed point on which to base the dating. Previous studies have documented that most non-Africans derive 1–4% ancestry from Neanderthals from an admixture event that occurred ∼37,000–86,000 y before present (yBP) (9, 10), with some analyses proposing a second event (around the same time) into the ancestors of East Asians (11, 12). Because the vast majority of ancient samples sequenced to date were discovered in Eurasia (with estimated ages of ∼2,000–45,000 yBP), postdate the Neanderthal admixture, and show evidence of Neanderthal ancestry, we used the Neanderthal gene flow as the shared event.The idea of our method is to estimate the date of Neanderthal gene flow separately for the extant and ancient genomes. Because the ancient sample is closer in time to the shared Neanderthal admixture event, we expect that the inferred dates of Neanderthal admixture will be more recent in ancient genomes (by an amount that is directly determined by the sample’s age) compared with the dates in the extant genomes. The difference in the dates thus provides an estimate of the amount of missing evolution: that is, the age of the ancient sample. An illustration of the idea is shown in SI Appendix, Fig. S1. An assumption in our approach is that the Neanderthal admixture into the ancestors of modern humans occurred approximately at the same time and that the same interbreeding events contributed to the ancestry of all of the non-African samples being compared. Deviations from this model could lead to incorrect age estimates. Our method is not applicable for dating genomes that do not have substantial Neanderthal ancestry, such as sub-Saharan African genomes.To date the Neanderthal admixture event, we used the insight that gene flow between genetically distinct populations, such as Neanderthals and modern humans, introduces blocks of archaic ancestry into the modern human background that break down at an approximately constant rate per generation as crossovers occur (13–15). Thus, by jointly modeling the decay of Neanderthal ancestry and recombination rates across the genome, we can estimate the date of Neanderthal gene flow, measured in units of generations. Similar ideas have been used to estimate the time of admixture events between contemporary human populations (14–16), as well as between Eurasians and Neanderthals (9, 17). An important feature of our method is that it is expected to give more precise results for samples that are older because these samples are closer in time to the Neanderthal introgression event, thus it is easier to accurately estimate the time of the admixture event for them. Thus, unlike ¹⁴C dating, the genetic approach becomes more reliable with age and, in that regard, complements ¹⁴C dating.     

Molecular detection and quantification of pertussis and correlation with clinical outcomes in children

Pertussis is an under-recognized serious infection. Conventional cultures are insensitive and of limited utility after antibiotic exposure. We corroborated the utility of real-time polymerase chain reaction (PCR) as a diagnostic tool in pertussis and investigated its role as a prognostic tool by evaluating its benefit in the quantification of pertussis bacterial load. All pertussis-positive PCR tests (n = 104) submitted over 5 years were collected for retrospective study. PCR cycle threshold was compared to quantitative culture in 43. Compared to PCR, the sensitivity of culture was 41%. Our PCR assay reliably quantified bacterial load and was quantitatively reproducible. Higher bacterial load correlated with longer duration of hospitalization (P = 0.0003), and multivariate logistic regression models demonstrated this association to be independent. The study confirmed PCR as a superior diagnostic tool in pertussis. PCR quantification of bacterial load at initial diagnosis predicts later clinical disease severity, suggesting a potential benefit of PCR as a prognostic tool in pertussis.     

Drotaverine hydrochloride versus hyoscine-N-butylbromide in augmentation of labor

Objectives: To study and compare the efficacy and side effects of drotaverine hydrochloride and hyoscine-N-butylbromide in the augmentation of labor. Methods: A prospective randomized trial of 150 women in active labor included 50 women given drotaverine (group 1), 50 women given hyoscine-N-butylbromide (group 2), and 50 women given no medication (group 3). Duration of labor, rate of cervical dilation, mode of delivery, side effects, and neonatal outcome were compared among the groups. Results: The mean duration of the active phase of labor was 4.48 ± 2.26 h, 3.9 ± 2.42 h, and 3.6 ± 2.07 h in groups 1, 2, and 3, respectively. The mean rate of cervical dilation was 2.6 cm/h, 2.4 cm/h, and 2.5 cm/h, respectively. The differences were not statistically significant. There was no difference in the duration of the second and third stages of labor. No adverse maternal or fetal outcomes were noted. Conclusion: Drotaverine hydrochloride and hyoscine-N-butylbromide do not have a role in augmentation of labor.