X , Y , and Z waves: extended structures in nonlinear lattices

We propose a new type of waveforms in two-dimensional (2D) and three-dimensional (3D) discrete media-multilegged extended nonlinear structures (ENSs), built as arrays of lattice solitons (tiles and stones, in the 2D and 3D cases, respectively). We study the stability of the tiles and stones analytically, and then extend them numerically to complete ENS forms for both 2D and 3D lattices, aiming to single out stable ENSs. The predicted patterns can be realized in Bose-Einstein condensates trapped in deep optical lattices, crystals built of microresonators, and 2D photonic crystals. In the latter case, the patterns provide for a technique for writing reconfigurable virtual partitions in multipurpose photonic devices.

Generalized abdominal visceral fat prediction models for black and white adults aged 17–65 y: the HERITAGE Family Study

OBJECTIVE

To determine if the relationship between abdominal visceral fat (AVF) and measures of adiposity are different between Black and White subjects and to develop valid field prediction models that accurately identify those individuals with AVF levels associated with high risk for chronic disease.

DESIGN

Cross-sectional measurements obtained from 91 Black men, 137 Black women, 227 White men, and 237 White women subjects, ages 17-65 y, who were participants in the HERITAGE Family Study, both at baseline and following 20 weeks of endurance training.

MEASUREMENTS

AVF, abdominal subcutaneous fat (ASF), abdominal total fat (ATF), and sagittal diameter (SagD) were measured by computed tomography (CT). Body density was determined by hydrostatic weighing and was used to estimate relative body fat. Arm, waist (WC), and hip circumferences and skinfold thickness measures were taken, and BMI was calculated from weight (kg) and height (m(2)). Since CT abdominal fat variables were skewed, a natural log transformation (Ln) was used to produce a normal distribution. The General Linear Model (GLM) procedure was used to test the relationship between AVF and two different groups of variables-CT and anthropometric.

RESULTS

The AVF of White men and women was significantly higher than that of Black men and women, independent of BMI, WHR, WC, and age, and was greater for men than for women. The CT model showed that the combination of SagD, Ln (ASF), age, and race accounted for 84 and 75% of the variance in AVF in men and women, respectively. The anthropometric model provided two valid generalized field AVF prediction equations. The Field-I equation, which included BMI, WHR, age and race, had an r(2) of 0.78 and 0.73 for men and women, respectively. The Field-II equation, which included BMI (women only), WC, age, and race, had an r(2) of 0.78 and 0.72 for men and women, respectively. The field model equations became less accurate as the estimated AVF increased.

CONCLUSIONS

(1) At the same age and level of adiposity, Black men and women have less AVF than White men and women. These differences are greater in men than in women. (2) The field regression equations can be generalized to the diverse group of adults studied, both in an untrained and trained state. However, their accuracy decreases with increasing levels of AVF.

Interactions among the beta2- and beta3- adrenergic receptor genes and total body fat and abdominal fat level in the HERITAGE Family Study

OBJECTIVE AND SUBJECTS

Interactions between markers in the beta2- and beta3-adrenergic receptor (ADR) genes and total body fat and computerized tomography-measured abdominal fat phenotypes were studied in the HERITAGE Family Study cohort of Black (n=205; 81 males and 124 females) and White (n=415; 198 males and 217 females) subjects before and after an endurance training program.

RESULTS

In Black subjects, beta2- and beta3-ADR gene variants showed evidence of interactions on changes in total body fat mass and abdominal fat area (P<0.005 and =0.010, respectively). Black subjects who were carriers of both beta2-ADR Arg16 and beta3-ADR Arg64 alleles had a greater decrease in total fat mass as well as abdominal total and subcutaneous, but not visceral fat areas in response to endurance training than subjects with other genotype combinations (P from 0.011 to 0.047). After correction for multiple tests, the findings remained essentially unchanged for total body fat mass and abdominal fat area, but became nonsignificant for subcutaneous fat area. The changes in abdominal fat correlated positively with the changes in fat mass (P<0.0001). The interactions between beta2 and beta3-ADR gene markers accounted for a maximum of 3% of the variances in the response of total fat mass and abdominal fat area to endurance training in Black subjects but it was not significant in White subjects.

CONCLUSION

Interactions between sequence variants in the beta2-beta3-ADR gene contributed to the changes in fat mass and abdominal adiposity in response to endurance training in Black subjects.

Familial aggregation of exercise heart rate and blood pressure in response to 20 weeks of endurance training: the HERITAGE family study

Changes of heart rate (HR) and blood pressure (BP) relative to baseline levels in response to an extended period of endurance training are indices of cardiovascular adaptability. Familial influences were investigated for HR and BP at work rates of 50 W and 60 % of the maximal oxygen uptake (VO2max) in response to 20 weeks of endurance training. A total of 481 participants from 99 sedentary White nuclear families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Each of these training response phenotypes was adjusted for the effects of age, BMI, cigarette smoking, baseline VO2max, and its baseline values in fathers, mothers, sons and daughters, respectively. We found that maximal heritabilities reached 34 % and 29 % for HR training responses at 50 W and 60 % of VO2 max, respectively. The heritability was 22 % for systolic BP (SBP) training response at 50 W, but negligible at 60 % of VO2max. No significant heritabilities were found for diastolic BP (DBP) training responses at either 50 W or 60 % of VO2max. Familial influences for exercise HR and BP training responses were also assessed in a total of 257 participants from 113 Black family units in HERITAGE. However, there was no significant familial resemblance, which may be attributable to the small sample size. In conclusion, HR and SBP training responses during submaximal exercise in Whites were influenced by a modest, but significant, familial component. These observations are therefore in contrast to substantial familial effects (heritability estimates of about 50 %) previously reported for these variables measured at baseline.

The effect of sex, age and race on estimating percentage body fat from body mass index: The Heritage Family Study

OBJECTIVE

To study the effects of sex, age and race on the relation between body mass index (BMI) and measured percent body fat (%fat).

DESIGN

Cross-sectional validation study of sedentary individuals.

SUBJECTS

The Heritage Family Study cohort of 665 black and white men and women who ranged in age from 17 to 65 y.

MEASUREMENTS

Body density determined from hydrostatic weighing. Percentage body fat determined with gender and race-specific, two-compartment models. BMI determined from height and weight, and sex and race in dummy coded form.

RESULTS

Polynomial regression showed that the relationship between %fat and BMI was quadratic for both men and women. A natural log transformation of BMI adjusted for the non-linearity. Test for homogeneity of log transformed BMI and gender showed that the male-female slopes were within random variance, but the intercepts differed. For the same BMI, the %fat of females was 10.4% higher than that of males. General linear models analysis of the women's data showed that age, race and race-by-BMI interaction were independently related to %fat. The same analysis applied to the men's data showed that %fat was not just a function of BMI, but also age and age-by-BMI interaction. Multiple regression analyses provided models that defined the bias.

CONCLUSIONS

These data and results published in the literature show that BMI and %fat relationship are not independent of age and gender. These data showed a race effect for women, but not men. The failure to adjust for these sources of bias resulted in substantial differences in the proportion of subjects defined as obese by measured %fat.

The hormone-sensitive lipase gene and body composition: the HERITAGE Family Study

OBJECTIVE

To investigate whether the C-60G polymorphism and other markers in the hormone-sensitive lipase (LIPE) gene are associated with baseline body composition and free-fatty acid (FFA) concentrations measured at rest and during low-intensity exercise in white and black subjects participating in the HERITAGE Family Study.

SUBJECTS

Adult sedentary white (245 men and 258 women) and black (91 men and 185 women) subjects.

MEASUREMENTS

body mass index (BMI); fat mass (FAT); percentage body fat (%FAT); fat-free mass (FATFR); sum of eight skinfolds (SF8); subcutaneous (ASF), visceral (AVF) and total (ATF) abdominal fat areas assessed by CT scan; plasma FFA concentrations measured at rest (FFAR), at a power output of 50 W (FFA50) and at a relative power output of 60% of VO(2max) (FFA60%); and fasting insulin (INS).

STATISTICAL ANALYSIS

Association between the C-60G polymorphism of the LIPE gene and each phenotype was tested separately in men and women using ANCOVA with the effects of age and race as covariates and with further adjustment for FAT for ASF, AVF, ATF, FFAR, FFA50 and FFA60%. Secondly, owing to significant gene-by-race interaction, associations were investigated separately in each of the two race groups. Linkage was tested with the C-60G polymorphism, a dinucleotide repeat polymorphism in the intron 7 of the LIPE gene and two microsatellites markers (D19S178 and D19S903) flanking the LIPE gene.

RESULTS

There were no race differences in the allele frequencies of the C-60G polymorphism of the LIPE gene. No association or gene-by-race interaction was observed in men. However, in women, strong gene-by-race interactions were observed for BMI (P=0.0005), FAT (P=0.0007), %FAT (P=0.0003), SF8 (P=0.0001), ASF (P=0.03) and ATF (P=0.01). When the analysis was performed separately in each race, white women carriers of the -60G allele exhibited lower %FAT (P=0.005) and SF8 (P=0.01) than non-carriers, while in black women, the -60G allele was associated with higher BMI (P=0.004), FAT (P=0.009), %FAT (P=0.01) and SF8 (P=0.0009). These associations were no longer significant after adjusting for INS. Evidence of linkage was observed in whites with ATF, FFAR, FFA50 and FFA60%.

CONCLUSION

These results suggest that the C-60G polymorphism in the LIPE gene plays a role in determining body composition and that its effect is sex-, race- and insulin-dependent.

Variability in the response of HDL cholesterol to exercise training in the HERITAGE Family Study

In the HERITAGE Family Study, 675 sedentary, healthy, white and black men and women, aged 17 to 65 years, performed 20 weeks of supervised cycle ergometer exercise at the same relative intensity and weekly volume. As a group, subjects had normal mean baseline lipid levels for North Americans with the exception of below average high density lipoprotein cholesterol (HDL-C) levels. A significant mean increase in plasma HDL-C of 3.6 % was observed; however, there was marked variability in responsiveness to training, ranging from a mean 9.3 % decrease in Quartile 1 of HDL-C response to a mean 18 % increase in Quartile 4 (P < 0.0001 by ANOVA). Parallel changes in HDL(2)-C and HDL(3)-C, apolipoprotein A-I levels, and lipoprotein lipase activity were noted across quartiles. The change in HDL-C across quartiles was inversely related to baseline HDL-C (p < 0.0001) and to changes with training in plasma triglycerides (p = 0.0007). No significant differences in HDL-C response were observed across quartiles by sex, race, age, or increase in VO(2)max with training; however, weak positive associations were observed with age-adjusted education level and with reduction in abdominal fat and increase in VO(2)max at the ventilatory threshold following training. Multivariate regression analysis including baseline variables and training responses only accounted for 15.5 % of the variability in the HDL-C response to training. Thus, marked variability was found in the HDL-C response to the same endurance exercise training stimulus with only a modest amount of the response predictable by identified nongenetic factors.

Race differences in the response of postheparin plasma lipoprotein lipase and hepatic lipase activities to endurance exercise training in men: results from the HERITAGE Family Study

Endurance exercise training is known to produce favorable changes in the metabolic profile including reduced plasma triglyceride (TG) and increased high-density lipoprotein (HDL) cholesterol concentrations. These metabolic improvements are likely to contribute to the reduced coronary heart disease (CHD) risk often observed in physically active individuals. However, the physiological mechanisms responsible for such improvements in TG and HDL cholesterol concentrations with endurance exercise are not fully understood. The effect of a 20-week endurance exercise training program on plasma lipoproteins as well as on post-heparin plasma lipoprotein lipase (PH-LPL) and hepatic lipase (PH-HL) activities were therefore examined in a sample of 200 White and 69 Black men who were part of the HERITAGE Family Study. As expected, there were decreases in adiposity and in abdominal fat accumulation following training in both White and Black men. We also found that exercise training was associated with decreases in plasma cholesterol, TG and apolipoprotein B levels, as well as with an increase in HDL cholesterol concentrations in White men. In contrast, Black men showed an increase only in HDL(2) cholesterol over the 20-week period. Higher PH-LPL and lower PH-HL activities were noted in both ethnic groups at follow-up. Whereas in White men improvement of the lipoprotein-lipid profile was related to increased PH-LPL activity, no association between PH-LPL (or PH-HL) and lipoprotein-lipid variables was observed in Black men. Results of the present study suggest that in Whites, the increase in PH-LPL activity in response to endurance exercise training is associated with a better lipoprotein-lipid profile, therefore reducing CHD risk. However, the generally better metabolic profile of Black individuals may minimize further improvement of lipoprotein-lipid concentrations by exercise training.

Formation of a tyrosyl radical intermediate in Proteus mirabilis catalase by directed mutagenesis and consequences for nucleotide reactivity

Proteus mirabilis catalase (PMC) belongs to the family of NADPH binding catalases. The function of NADPH in these enzymes is still a matter of debate. This study presents the effects of two independent phenylalanine mutations (F194 and F215), located between NADPH and heme in the PMC structure. The phenylalanines were replaced with tyrosines which we predicted could carry radicals in a NADPH-heme electron transfer. The X-ray crystal structures of the two mutants indicated that neither the binding site of NADPH nor the immediate environment of the residues was affected by the mutations. Measurements using H2O2 as a substrate confirmed that the variants were as active as the native enzyme. With equivalent amounts of peroxoacetic acid, wild-type PMC, F215Y PMC, and beef liver catalase (BLC) formed a stable compound I, while the F194Y PMC variant produced a compound I which was rapidly transformed into compound II and a tyrosyl radical. EPR studies showed that this radical, generated by the oxidation of Y194, was not related to the previously observed radical in BLC, located on Y369. In the presence of excess NADPH, compound I was reduced to a resting enzyme (k(obs) = 1.7 min(-1)) in a two-electron process. This was independent of the enzyme's origin and did not require any thus far identified tyrosyl radicals. Conversely, the presence of a tyrosyl radical in F194Y PMC greatly enhanced the oxidation of reduced beta-nicotinamide mononucleotide under a steady-state H2O2 flow with observable compound II. This process could involve a one-electron reduction of compound I via Y194.

Genome-wide linkage scan to detect loci influencing levels of dehydroepiandrosterones in the HERITAGE Family Study

A genome-wide linkage scan was performed to identify genomic regions that influence levels of dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and DHEA fatty acid esters (DHEA-FA) at baseline and in response to 20 weeks of endurance exercise training in sedentary white and black participants in the HERITAGE Family Study. The baseline levels were log-transformed and adjusted for the effects of age and sex prior to genetic analysis. The training responses were adjusted for the effects of age, sex, and the baseline values. A total of 509 autosomal component polymorphic markers were used for the genome scan with an average spacing of 6.0 Mb. Multipoint variance components linkage analyses were performed in nuclear families containing 360 white and 106 black sibling pairs. We found 5 genomic regions with significant linkages for baseline DHEA-FA in whites, with log odd (LOD) scores over 3.6 (P < 2 x 10(-5)). They include (1) D1S468 (LOD 4.56, 2.533 Mb, 1p36.22); (2) D2S177 (LOD 5.65, 52.663 Mb, 2p16.3); (3) D4S2397 (LOD 3.98, 32.246 Mb, 4p15.2); (4) the paraoxonase loci (LOD 3.93 approximately 3.99, 101.544 approximately 102.933 Mb, 7q21.3), and D7S821 (LOD 3.88, 104.497 Mb, 7q22.1); and (5) D12S372 (LOD 4.66, 2.129 Mb, 12q13.33). In addition, we obtained evidence of suggestive linkages (2.2 < LOD < 3.6; 2 x 10(-5) < P < 7 x 10(-4)) on chromosomes 3p, 6q, and 8q for baseline DHEAS; on chromosomes 2q, 3p, 9q, 10p, 16q, and 17p for baseline DHEA-FA in whites; and on chromosomes 9q and 11p for baseline DHEA in blacks. This is the first genome-wide linkage scan searching for genomic regions influencing human DHEA levels. Several potential candidate genes are located in these genomic regions, which warrant further studies in HERITAGE and other cohorts.

Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study

The purpose of this study was to evaluate the effect of exercise training intensity relative to the ventilatory threshold (VT) on changes in work (watts) and VO2 at the ventilatory threshold and at maximal exercise in previously sedentary participants in the HERITAGE Family Study. We hypothesized that those who exercised below their VT would improve less in VO2 at the ventilatory threshold (VO2vt) and VO2max than those who trained at an intensity greater than their VT. Supervised cycle ergometer training was performed at the 4 participating clinical centers, 3 times a week for 20 weeks. Exercise training progressed from the HR corresponding to 55% VO2max for 30 minutes to the HR associated with 75% VO2max for 50 minutes for the final 6 weeks. VT was determined at baseline and after exercise training using standardized methods. 432 sedentary white and black men (n = 224) and women (n = 208), aged 17 to 65 years, were retrospectively divided into groups based on whether exercise training was initiated below, at, or above VT.

RESULTS

1) Training intensity (relative to VT) accounting for about 26% of the improvement in VO2vt (R2 = 0.26, p < 0.0001). 2) The absolute intensity of training in watts (W) accounted for approximately 56% of the training effect at VT (R2 = 0.56, p < 0.0001) with post-training watts at VT (VT(watts)) being not significantly different than W during training (p > 0.70). 3) Training intensity (relative to VT) had no effect on DeltaVO2max. These data clearly show that as a result of aerobic training both the VO2 and W associated with VT respond and become similar to the absolute intensity of sustained (3 x /week for 50 min) aerobic exercise training. Higher intensities of exercise, relative to VT, result in larger gains in VO2vt but not in VO2max.

Relationship of changes in maximal and submaximal aerobic fitness to changes in cardiovascular disease and non-insulin-dependent diabetes mellitus risk factors with endurance training: the HERITAGE Family Study

The purpose of this study was to determine the relationship between changes in maximal oxygen uptake (VO2 max) and submaximal markers of aerobic fitness and changes in risk factors for cardiovascular disease (CVD) and non-insulin-dependent diabetes mellitus (NIDDM) consequent to a 20-week endurance training program. The 502 participants in this study were healthy and previously sedentary men (n = 250) and women (n = 252) of varying age (17 to 65 years) and race (blacks n = 142; whites n = 360) who had completed the HERITAGE Family Study testing and training protocol. Following baseline measurements, participants trained on cycle ergometers 3 days/week for a total of 60 exercise sessions starting at the heart rate (HR) associated with 55% of VO2 max for 30 minutes/session. This was progressively increased to the HR associated with 75% of VO2 max for 50 minutes/session, which was maintained during the last 6 weeks. VO2 max, heart rate at 50 W, power output at 60% of VO2 max, lipids and lipoproteins, resting blood pressure, body composition including abdominal fat (computed tomography [CT] scan), and blood glucose and insulin at rest and at peak following an intravenous glucose tolerance test (IVGTT) were determined both before and after training. Following training, there were significant increases in VO2 max (16%) and the power output at 60% of VO2 max and a significant decrease in HR at 50 W. These changes in markers of aerobic fitness were significantly correlated only to the changes in the body composition variables and the lipids and lipoproteins. Further, there was considerable individual variation in response for all variables studied. Finally, when risk factor data were analyzed by quartile of change in VO2 max, there were few significant relationships. It is concluded that there is a significant relationship between changes in markers of aerobic fitness and changes in several risk factors for CVD and NIDDM. However, the magnitude of these relationships is small.

Population differences in the pattern of familial aggregation for sex hormone-binding globulin and its response to exercise training: the HERITAGE Family Study

Familial influences were investigated for baseline sex hormone-binding globulin (SHBG) and its response (post-training minus baseline) to a 20-week endurance exercise training program. One hundred, eighty-four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex-by-generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h(2) = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h(2) = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size.

Familial resemblance in ventilatory threshold: the HERITAGE Family Study

PURPOSE

This study investigates the familial resemblance of VO2 at the ventilatory threshold (VO2vt) from 199 nuclear families (100 White and 99 Black) participating in the HERITAGE Family Study.

METHODS

VO2vt (mL x min(-1)) was determined in the sedentary state and again after 20 wk of aerobic cycle ergometer exercise training in 339 individuals (131 parents and 228 of their offspring), aged between 17 and 65 yr. VO2vt was adjusted for weight, age, fat mass, and fat-free mass by using regression methods.

RESULTS

There was evidence for significant familial resemblance in the sedentary state for VO2vt (maximal heritability = 58% in White and 54% in Black families) and VO2vt/VO2max (maximal heritability = 38% in White and 39% in Black families). Spouse, sibling, and parent-offspring relationships for VO2vt were significant at baseline, suggesting that both genetic and shared environmental factors may contribute to the familial resemblance in the sedentary state. There was a moderate familial component in the response of VO2vt to aerobic exercise training in Whites (22%) and a larger component in Blacks (51%). In Blacks, the familial effect for VO2vt/VO2max appeared to be accounted for by fat and fat-free mass.

CONCLUSION

These results show a strong familial contribution to VO2vt in the sedentary state and to the response of VO2vt to aerobic exercise training.

TGF-beta(1) gene-race interactions for resting and exercise blood pressure in the HERITAGE Family Study

We examined the possible association between a transforming growth factor (TGF)-beta(1) gene polymorphism in codon 10 and blood pressure (BP) at rest, in acute response to exercise in the pretrained (sedentary) and trained states, as well as in its training response (Delta) to 20 wk of endurance exercise. Subjects were 257 black and 480 white, healthy sedentary normotensive subjects from the HERITAGE Family Study. The polymorphism was detected by polymerase chain reaction and digestion with the Msp A1 I endonuclease yielding a wild (leucine-10) and a mutant (proline-10) allele. Resting and exercise [50 W plus 60, 80, and 100% maximal oxygen consumption (VO(2)(max))] BP were determined before and after training. Significant (P < 0.05) race-genotype interactions were found for systolic (S) BP in both the sedentary and trained states. Among whites but not in blacks, the TGF-beta(1) genotypes were significantly (P < 0.05) associated with sedentary-state SBP at rest, at 50 W, and at 60 and 100% VO(2)(max)as well as with trained-state SBP at rest and at 80 and 100% VO(2)(max). The leucine-10 homozygotes had significantly (P < 0.05) lower SBP than proline-10 homozygotes. DeltaBP was not significantly associated with genotype. These results support the hypothesis of an association between the TGF-beta(1) marker in codon 10 and SBP at rest and in response to acute exercise in whites but not in blacks.

Evidence of LPL gene-exercise interaction for body fat and LPL activity: the HERITAGE Family Study

Evidence of a gene-exercise interaction for traits related to body composition is limited. Here, the association between the lipoprotein lipase (LPL) S447X polymorphism and changes in body mass index, fat mass, percent body fat, abdominal visceral fat measured by computed tomography, and post-heparin plasma LPL activity in response to 20 wk of endurance training was investigated in 741 adult white and black subjects. Changes were compared between carriers and noncarriers of the X447 allele after adjustment for the effects of age and pretraining values. No evidence of association was observed in men. However, white women carrying the X447 allele exhibited greater reductions of body mass index (P = 0.01), fat mass (P = 0.01), and percent body fat (P = 0.03); in black women, the carriers exhibited a greater reduction of abdominal visceral fat (P = 0.05) and a greater increase in post-heparin LPL activity (P = 0.02). These results suggest that the LPL S447X polymorphism influences the training-induced changes in body fat and post-heparin LPL activity in women but not in men.

Characterization of a novel complex from halophilic archaebacteria, which displays chaperone-like activities in vitro

We isolated a protein, P45, from the extreme halophilic archaeon Haloarcula marismortui, which displays molecular chaperone activities in vitro. P45 is a weak ATPase that assembles into a large ring-shaped oligomeric complex comprising about 10 subunits. The protein shows no significant homology to any known protein. P45 forms complexes with halophilic malate dehydrogenase during its salt-dependent denaturation/renaturation and decreases the rate of deactivation of the enzyme in an ATP-dependent manner. Compared with other halophilic proteins, the P45 complex appears to be much less dependent on salt for its various activities or stability. In vivo experiments showed that P45 accumulates when cells are exposed to a low salt environment. We suggest, therefore, that P45 could protect halophilic proteins against denaturation under conditions of cellular hyposaline stress.

Familial resemblance for free androgens and androgen glucuronides in sedentary black and white individuals: the HERITAGE Family Study. Health, Risk Factors, Exercise Training and Genetics

Familial correlation analyses were used to evaluate the familial aggregation of plasma androgens and androgen glucuronides (testosterone (TESTO), dihydrotestosterone (DHT), androstane-3 alpha,17 beta-diol glucuronide (3 alpha-DIOL-G), and androsterone glucuronide (ADT-G)) in 505 members of 99 white families and 296 members of 111 black families participating in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study. Each of these four measures was determined by RIA after separation of conjugated and unconjugated steroid using C18 column chromatography. All participants were sedentary prior to being including in this study. Significant spouse correlations, as well as parent-offspring and sibling correlations, were found for TESTO, DHT, 3 alpha-DIOL-G, and ADT-G in the white sample, suggesting that common familial environments and genes contribute to the familial resemblance. In the black sample, significant sibling and parent-offspring correlations were found for all four phenotypes, while the spouse correlation was marginally significant for 3 alpha-DIOL-G and not significant for TESTO, DHT, and ADT-G. The non-significance of spouse correlations in the black individuals may be due to the small number of spouse pairs. The maximal heritability estimates of TESTO, DHT, 3 alpha-DIOL-G, and ADT-G were 69%, 87%, 74%, and 56% for white individuals and 70%, 73%, 62%, and 48% for black individuals respectively. Sex differences in heritability estimates were found in the white individuals, but they were less dramatic in the black individuals. In conclusion, plasma levels of androgens and androgen glucuronides are highly heritable in both white individuals and black individuals. There are notable sex differences in the white individuals.

Race differences in the pattern of familial aggregation for dehydroepiandrosterone sulfate and its responsiveness to training in the HERITAGE Family Study

Using a familial correlation model to assess familial influences, baseline dehydroepiandrosterone sulfate (DHEAS) and its change (post-training minus baseline) in response to a 20-week endurance exercise training program were analyzed in 85 black families who participated in the HERITAGE Family Study (HERITAGE). Baseline levels were adjusted for a polynomial in age, and the training response was adjusted for a polynomial in age, as well as the baseline values, within 4 sex-by-generation groups before genetic analysis. We found that the maximal heritability for baseline DHEAS reached 66% (with no sex and generation differences) in black families, which is slightly (but not significantly) higher than the estimate (58%) reported previously in 99 white families in HERITAGE. Whereas weak, but significant, familial effects (26%) for the training response were previously reported for whites in HERITAGE, they were undetectable in the present study. Furthermore, we found heterogeneity in the pattern of familial aggregation (primarily due to different spouse and parent-offspring correlations) for both the baseline and its training response between blacks and whites. In conclusion, baseline DHEAS levels in blacks were also determined by substantial familial factors (just as for whites), independent of the effects of age and sex. Genetic and nongenetic familial components influencing baseline DHEAS levels in both races may be different.

Solution structure of the squash trypsin inhibitor MCoTI-II. A new family for cyclic knottins

The "knottin" fold is a stable cysteine-rich scaffold, in which one disulfide crosses the macrocycle made by two other disulfides and the connecting backbone segments. This scaffold is found in several protein families with no evolutionary relationships. In the past few years, several homologous peptides from the Rubiaceae and Violaceae families were shown to define a new structural family based on macrocyclic knottin fold. We recently isolated from Momordica cochinchinensis seeds the first known macrocyclic squash trypsin inhibitors. These compounds are the first members of a new family of cyclic knottins. In this paper, we present NMR structural studies of one of them, MCoTI-II, and of a beta-Asp rearranged form, MCoTI-IIb. Both compounds display similar and well-defined conformations. These cyclic squash inhibitors share a similar conformation with noncyclic squash inhibitors such as CPTI-II, and it is postulated that the main effect of the cyclization is a reduced sensitivity to exo-proteases. On the contrary, clear differences were detected with the three-dimensional structures of other known cyclic knottins, i.e., kalata B1 or circulin A. The two-disulfide cystine-stabilized beta-sheet motif [Heitz et al. (1999) Biochemistry 38, 10615-10625] is conserved in the two families, whereas in the C-to-N linker, one disulfide bridge and one loop are differently located. The molecular surface of MCoTI-II is almost entirely charged in contrast to circulin A that displays a well-marked amphiphilic character. These differences might explain why the isolated macrocyclic squash inhibitors from M. cochinchinensis display no significant antibacterial activity, whereas circulins and kalata B1 do.

Studies of acceptor site specificities for three members of UDP-GalNAc:N-acetylgalactosaminyltransferases by using a synthetic peptide mimicking the tandem repeat of MUC5AC

The acceptor specificity of three major isoforms of UDP-GalNAc:polypeptide N-acetylgalactosaminyltranferases (murine recombinant proteins GaNTase-T1, -T2 and -T3) was investigated using the synthetic peptide (GTTPSPVPTTSTTSAP) containing clusters of threonine residues mimicking the mucin tandem repeat unit of MUC5AC. The O-glycosylated products obtained after in vitro reactions were fractionated by capillary electrophoresis and the purified glycopeptides were characterized by MALDI mass spectrometry (number of O-GalNAc residues) and by Edman degradation (site location). A maximum of three GalNAc residues was transferred into the MUC5AC motif peptide and the preferential order of incorporation for each GaNTase isoform was determined. Our results suggest that clusters of threonine appear to be essential for site recognition of peptide backbone by the ubiquitous GaNTases and also support the notion that the different GaNTase isoforms with varying substrate specificities are involved in a hierarchical order of O-glycosylation processing of the mucin-type O-glycoproteins.

Effects of endurance exercise training on plasma HDL cholesterol levels depend on levels of triglycerides: evidence from men of the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study

High density lipoprotein (HDL) cholesterol concentrations have been shown to increase with regular endurance exercise and, therefore, can contribute to a lower risk of coronary heart disease in physically active individuals compared with sedentary subjects. Although low HDL cholesterol levels are frequently observed in combination with hypertriglyceridemia, some individuals may be characterized by isolated hypoalphalipoproteinemia, ie, low HDL cholesterol levels in the absence of elevated triglyceride (TG) concentrations. The present study compared the responses of numerous lipoprotein-lipid variables to a 20-week endurance exercise training program in men categorized on the basis of baseline TG and HDL cholesterol concentrations: (1) low TG and high HDL cholesterol (normolipidemia), (2) low TG and low HDL cholesterol (isolated low HDL cholesterol), (3) high TG and high HDL cholesterol (isolated high TGs), and (4) high TGs and low HDL cholesterol (high TG/low HDL cholesterol). A series of physical and metabolic variables was measured before and after the training program in a sample of 200 men enrolled in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study. At baseline, men with high TG/low HDL cholesterol had more visceral adipose tissue than did men with isolated low HDL cholesterol and men with normolipidemia. The 0.4% (not significant) exercise-induced increase in HDL cholesterol levels in men with isolated low HDL cholesterol suggests that they did not benefit from the "HDL-raising" effect of exercise. In contrast, men with high TG/low HDL cholesterol showed a significant increase in HDL cholesterol levels (4.9%, P<0.005). Whereas both subgroups of men with elevated TG levels showed reductions in plasma TGs ( approximately -15.0%, P<0.005), only those with high TG/low HDL cholesterol showed significantly reduced apolipoprotein B levels at the end of the study (-6.0%, P<0.005). Multiple regression analyses revealed that the exercise-induced change in abdominal subcutaneous adipose tissue (10.6%, P<0.01) was the only significant correlate of the increase in plasma HDL cholesterol with training in men with high TG/low HDL cholesterol. Results of the present study suggest that regular endurance exercise training may be particularly helpful in men with low HDL cholesterol, elevated TGs, and abdominal obesity.

Familial resemblance for glucose and insulin metabolism indices derived from an intravenous glucose tolerance test in Blacks and Whites of the HERITAGE Family Study

Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia, is a complex disease primarily caused by impairment in insulin sensitivity (SI) and insulin secretion. While a strong genetic component for T2DM is well established, there are few reports on racial differences in the magnitude of the genetic effects of T2DM and indices of glucose and insulin metabolism. We report here on the familial resemblance for traits related to glucose metabolism at pre-exercise training levels in 492 members from 99 sedentary White families and 259 members from 108 Black families participating in the multicenter HERITAGE Family Study. All these traits were obtained from the frequently sampled intravenous glucose tolerance test (IVGTT). They include glucose disappearance index (Kg), an overall index for glucose tolerance, acute insulin response to glucose (AIR(Glucose)) which is an index for insulin secretion, and those derived from the minimal model including SI and the disposition index (DI). DI, derived as the product of SI and AIR(Glucose), is a measure of the activity of the B-cells adjusted for insulin resistance. After adjustment for age, sex, and body mass index, the maximal heritability estimates in Blacks (Whites) are 48+/-14% (25+/-8%) for Kg, 44+/-14% (46+/-8%) for AIR(Glucose), 38+/-12% (44+/-8%) for SI and 32+/-14% (24+/-8%) for DI. Interestingly, Blacks have higher heritability for overall glucose tolerance than Whites but there is no race difference in heritability estimates for insulin sensitivity or insulin secretion.