Quantitative trait loci for maximal exercise capacity phenotypes and their responses to training in the HERITAGE Family Study

The purpose of this study was to identify regions of the human genome linked to maximal oxygen uptake (V̇o2 max) and maximal power output (MPO), and their response to a standardized 20-wk endurance-training program in sedentary black and white subjects. A total of 509 polymorphic markers covering the 22 autosomes were used in the genome-wide linkage scan. Baseline phenotypes were adjusted for age, sex, and body mass, whereas the training responses were adjusted for age, sex, and the baseline values. Regression-based single- and multipoint linkage analyses were used. In the sedentary state, a total of 351 and 102 sibling pairs were available for whites and blacks, respectively, and 329 and 90 sibling pairs, respectively, for the training response phenotypes. Baseline V̇o2 maxshowed promising linkage ( P < 0.0023) with 11p15.1 (whites), and suggestive evidence of linkage (0.01 > P > 0.0023) was found on 1p31, 7q32, and 7q36 (blacks). Baseline MPO exhibited promising linkage on 10q23 and suggestive evidence of linkage on 13q33 and 18q11-q12 (whites). V̇o2 maxtraining response yielded promising linkages with markers on 1p31 (blacks) and suggestive on 4q27, 7q34, and 13q12 (whites) and on 16q22 and 20q13.1 (blacks). Training-induced changes in MPO showed promising linkages on 5q23 (whites) and suggestive on 1q21, 4p15.1, and 4p13 (whites) and on 1q22 and 13q11 (blacks). In conclusion, the strongest evidence of linkage was found on chromosomal regions 11p15 and 10q23 for V̇o2 maxand MPO in the sedentary state and on chromosomes 1p31 and 5q23 for their responsiveness to training. These chromosomal regions harbor several candidate genes that deserve further investigation.

Genome-wide linkage scan reveals multiple susceptibility loci influencing lipid and lipoprotein levels in the Quebec Family Study

A genome-wide linkage study was performed to identify chromosomal regions harboring genes influencing lipid and lipoprotein levels. Linkage analyses were conducted for four quantitative lipoprotein/lipid traits, i.e., total cholesterol, triglyceride, HDL-cholesterol (HDL-C), and LDL-C concentrations, in 930 subjects enrolled in the Québec Family Study. A maximum of 534 pairs of siblings from 292 nuclear families were available. Linkage was tested using both allele-sharing and variance-component linkage methods. The strongest evidence of linkage was found on chromosome 12q14.1 at marker D12S334 for HDL-C, with a logarithm of the odds (LOD) score of 4.06. Chromosomal regions harboring quantitative trait loci (QTLs) for LDL-C included 1q43 (LOD = 2.50), 11q23.2 (LOD = 3.22), 15q26.1 (LOD = 3.11), and 19q13.32 (LOD = 3.59). In the case of triglycerides, three markers located on 2p14, 11p13, and 11q24.1 provided suggestive evidence of linkage (LOD > 1.75). Tests for total cholesterol levels yielded significant evidence of linkage at 15q26.1 and 18q22.3 with the allele-sharing linkage method, but the results were nonsignificant with the variance-component method. In conclusion, this genome scan provides evidence for several QTLs influencing lipid and lipoprotein levels. Promising candidate genes were located in the vicinity of the genomic regions showing evidence of linkage.

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.

The agouti-related protein and body fatness in humans

OBJECTIVE

The objective of this study was to examine the impact of a single nucleotide polymorphism (SNP) (-38C>T) in the promoter of the human agouti-related protein (hAgRP) gene on promoter affinity for transcription factors (TFs) and its possible association with body composition phenotypes.

DESIGN

Electrophoretic mobility shift assays for the functional studies and association analyses for the population studies.

SUBJECTS AND METHODS

Nuclear extracts were isolated from the mouse hypothalamus cell line GT1-7 and subjected to binding assays using oligonucleotide probes corresponding to the -38C>T region and an antibody for the E12/E47 TFs. Individuals (n = 259) from the HERITAGE Family Study were genotyped for the -38C>T SNP and used in the association studies.

RESULTS

Electrophoretic mobility shift and supershift assays confirmed binding of the E12/E47 TF to the -38C>T site in a genotype-dependent manner. The T allele was found exclusively in the black subjects while the genotype with the higher binding affinity, CC, was significantly associated with high BMI, fat mass, and percent body fat in the black subjects of the HERITAGE Family Study.

CONCLUSIONS

The E12/E47 TF could play a role in the regulation of hAgRP expression while the population studies suggest that the TT genotype of the -38C>T SNP could play a protective role against the development of obesity in the black population of the HERITAGE Family Study.

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.

Familial aggregation of seven-year changes in blood pressure in Canada

OBJECTIVE

To determine the familial resemblance for baseline and seven-year changes in blood pressure in the Canadian population.

METHODS

The study participants were 857 people from 348 families in the 1988 Campbell's Survey, which was a seven-year follow-up of the Canada Fitness Survey. Systolic and diastolic blood pressures were measured at baseline and at follow-up, and were adjusted for age and body mass index by using regression analysis. Familial correlation models were fit to the data by using path analysis, and maximal heritabilities were calculated from the most parsimonious models.

RESULTS

There was significant familial resemblance for baseline blood pressure and changes in blood pressure. In general, all classes of familial correlations (spousal, parent-offspring and sibling) were significant and were of comparable magnitude. The maximal heritabilities, which are influenced to an unknown degree by genes and shared environmental factors, were 50% and 70% for diastolic and systolic blood pressures, respectively, and 66% and 41% for seven-year changes in diastolic and systolic blood pressures, respectively.

CONCLUSIONS

There is significant familial aggregation for blood pressure and for natural changes in blood pressure in the Canadian population. Genes may be important in explaining the familial resemblance for blood pressure; however, the presence of significant spousal correlations suggests that shared lifestyle and family environments are also important factors in the familial aggregation.

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.

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.

Negative pressure effects on mechanically opposing pharyngeal muscles in awake and sleeping goats

Our aim was to investigate the effects of the negative pressure reflex on mechanically opposing pharyngeal muscles during wakefulness, slow-wave sleep (SWS), and rapid eye movement (REM) sleep. In four goats with isolated upper airways, we measured tracheal airflow and electrical activity of the thyropharyngeus (TP; constricting), the stylopharyngeus (SP; dilating), and the diaphragm (Dia). In the wakefulness state in response to negative pressure tests, TP decreased (65%), SP increased (198%), and tidal volume (VT) (66%) and rate of rise of Dia (Dia(slope), 69%) decreased (P < 0.02). Similarly, during SWS, the negative pressure response of TP (31%), VT (61%), and Dia(slope) (60%) decreased, whereas SP (113%) increased, relative to SWS control (P < 0.02). In REM sleep, the negative pressure response by TP and SP were small, whereas both VT (38%) and Dia(slope) (24%) were greatly decreased (P < 0.02) compared with REM control. Inspiratory duration remained unchanged in response to negative pressure tests in all states. These data provide evidence that mechanically opposing inspiratory and expiratory pharyngeal muscles are reciprocally controlled and their response to negative pressure are state dependent.

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.

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.

Individual autonomy and state involvement in health care

This article examines the ethical basis for government involvement in health care. It first provides the case for individual autonomy, focusing on the justifications--particularly ethical ones--for allowing individuals to make their own choices in health care, and to control more of their own resources in doing so. Next, it provides the opposite case--for abridging individual autonomy, and in particular, for redistributing resources from those who are well off to those who are not. The overriding reason for favouring the latter case, which trumps the notion of individual autonomy, is to ensure that individuals who are at a disadvantage have an equal probability of attaining good health.

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.

Genomic scan for exercise blood pressure in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study

Agenome-wide linkage scan was performed for genes affecting submaximal exercise systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the sedentary state and their responses to a standardized endurance training program. A total of 344 polymorphic markers were used, and 344 pairs of siblings from 99 white nuclear families and 102 sibling pairs from 105 black family units were available for the study. All subjects were healthy but sedentary at baseline. SBP and DBP were measured during exercise tests at 2 different intensities: 50 W (SBP50 and DBP50) and 80% of maximal oxygen consumption (SBP80 and DBP80). Baseline blood pressure phenotypes were adjusted for age, gender, and body mass index, and the training responses (after training minus baseline [Delta]) were adjusted for age, gender, baseline body mass index, and baseline blood pressure. Two analytical strategies were used: a multipoint variance-components linkage analysis using all the family data and a single-point linkage analysis using pairs of siblings. In whites, promising linkages (lod score >1.75) were detected for baseline SBP80 on 10q23-q24 and for DeltaSBP50 on 8q21. In addition, several chromosomal regions with suggestive evidence of linkage (lod score 1.0 to 1.75) were observed for SBP50 (22q11.2-q13), DBP50 (6q23-q27), SBP80 (2p24, 2q21, 14q11.1-q12, and 16q21), DBP80 (6q13-q21), DeltaSBP50 (7p12-p13), and DeltaDBP50 (5q31-q32). In blacks, DBP50, DBP80, and DeltaDBP80 showed promising quantitative trait loci on 18p11.2, 11q13-q21, and 10q21-q23, respectively. Suggestive linkages were evident for DBP50 on 2p22-p25, 11p15.5, and 18q21.1; for SBP80 on 6q21-q21, 6q31-q36, 12q12-q13, 15q12-q13, and 17q11-q12; and for DBP80 on 8q24, 10q21-q24, and 12p13. All the detected chromosomal regions include several potential candidate genes and therefore warrant further studies in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) cohort and other studies.

Genomic scan for genes affecting body composition before and after training in Caucasians from HERITAGE

An autosomal genomewide search for genes related to body composition and its changes after a 20-wk endurance-exercise training program has been completed in the HERITAGE Family Study. Phenotypes included body mass index (BMI), sum of eight skinfold thicknesses, fat mass (FM), fat-free mass, percent body fat (%Fat), and plasma leptin levels. A maximum of 364 sib-pairs from 99 Caucasian families was studied with the use of 344 markers with single-point and multipoint linkage analyses. Evidence of significant linkage was observed for changes in fat-free mass with the S100A and the insulin-like growth factor I genes (P = 0.0001). Suggestive evidence (2.0 < or = Lod < 3.0; 0.0001 < P < or = 0.001) was also observed for the changes in FM and %Fat at 1q31 and 18q21-q23, in %Fat with the uncoupling protein 2 and 3 genes, and in BMI at 5q14-q21. At baseline, suggestive evidence was observed for BMI at 8q23-q24, 10p15, and 14q11; for FM at 14q11; and for plasma leptin levels with the low-density lipoprotein receptor gene. This is the first genomic scan on genes involved in exercise-training-induced changes in body composition that could provide information on the determinants of weight loss.

Angiogenin gene-race interaction for resting and exercise BP phenotypes: the HERITAGE Family Study

We examined the association between an angiogenin gene polymorphism and blood pressure (BP) at rest and in response to acute exercise before and after a 20-wk endurance-training program. Subjects were 737 normotensive and borderline hypertensive subjects (257 black and 480 white). The polymorphism was detected by PCR and digestion with AvaII, yielding an allele of 253 bp or a rare allele of 194 + 59 bp. Resting and exercise [50 W; 60, 80, and 100% of maximal O2 consumption (VO2 max)] systolic (SBP) and diastolic BP were determined before and after training. Among blacks, adjusted SBP in the sedentary state was significantly lower in carriers of the rare allele at rest and exercise intensities of 60, 80, and 100% of VO2 max. In the trained state, carriers of the rare allele had a significantly (P < 0.05) lower SBP than did noncarriers at rest and at 80 and 100% of VO2 max. The genotypic effect observed among blacks was not evident among whites. Furthermore, change in BP (after--before) was not significantly associated with the genotype. In conclusion, the angiogenin gene AvaII polymorphism is associated with a lower SBP at rest and in response to acute high-intensity exercise in blacks but not in whites.

Endosonographic features predictive of lymph node metastasis

Endosonographic features that are thought to characterize lymph node metastasis were evaluated in 100 patients with esophageal carcinoma. Subjects underwent preoperative endoscopic ultrasonography to assess depth of tumor invasion (T stage) and lymph node metastasis (N stage). Endosonographically imaged lymph nodes were evaluated according to the following parameters: size, shape, border demarcation, and central echo pattern. Sensitivity and specificity of endosonography in detecting lymph node metastasis were 89.1% and 91.7%, respectively, when stringent criteria were used. When lymph nodes were imaged endosonographically, regardless of the specific features, the likelihood of N1 disease, was 86%, whereas when no lymph nodes were imaged, the chance of N0 disease was 79%. Endosonographic features predictive of malignancy in increasing order of importance were echo-poor (hypoechoic) structure, sharply demarcated borders, rounded contour, and size greater than 10 mm. Collectively, the EUS features produced an additive effect with respect to accuracy in the prediction of malignant lymph node involvement; malignancy could be predicted with 100% accuracy when all four features were present. These results demonstrate that a careful and systematic approach to the endosonographic assessment of lymph node metastasis can improve staging accuracy.

A genome-wide scan for abdominal fat assessed by computed tomography in the Québec Family Study

To identify chromosomal regions harboring genes influencing the propensity to store fat in the abdominal area, a genome-wide scan for abdominal fat was performed in the Quebec Family Study. Cross-sectional areas of the amount of abdominal total fat (ATF) and abdominal visceral fat (AVF) were assessed from a computed tomography scan taken at L4-L5 in 521 adult subjects. Abdominal subcutaneous fat (ASF) was obtained by computing the difference between ATF and AVF. The abdominal fat phenotypes were adjusted for age and sex effects as well as for total amount of body fat (kilogram of fat mass) measured by underwater weighing, and the adjusted phenotypes were used in linkage analyses. A total of 293 microsatellite markers spanning the 22 autosomal chromosomes were typed. The average intermarker distance was 11.9 cM. A maximum of 271 sib-pairs were available for single-point (SIBPAL) and 156 families for multipoint variance components (SEGPATH) linkage analyses. The strongest evidence of linkage was found on chromosome 12q24.3 between marker D12S2078 and ASF (logarithm of odds [LOD] = 2.88). Another marker (D12S1045) located within 2 cM of D12S2078 also provided evidence of sib-pair linkage with ASF (P = 0.019), ATF (P = 0.015), and AVF (P = 0.0007). Other regions with highly suggestive evidence (P < 0.0023 or LOD > or =1.75) of multipoint linkage and evidence (P < 0.05) of single-point linkage, all for ASF, included chromosomes 1p11.2, 4q32.1, 9q22.1, 12q22-q23, and 17q21.1. Three of these loci (1p11.2, 9q22.1, and 17q21.1) are close to genes involved in the regulation of sex steroid levels, whereas two others (4q32.1 and 17q21.1) are in the proximity of genes involved in the regulation of food intake. This first genome-wide scan for abdominal fat assessed by computed tomography indicates that there may be several loci determining the propensity to store fat in the abdominal depot and that some of these loci may influence the development of diabetes in obese subjects.

Lymphoscintigraphy using (99m)Tc filtered sulfur colloid in chylothorax: a case report

OBJECTIVE

A 66-y-old man was diagnosed with esophageal carcinoma and underwent a right thoracotomy and esophagectomy. Postoperatively, a recurring right pleural effusion developed. Because an attempt at lymphangiography failed, lymphoscintigraphy was suggested. Because of the inability to obtain radiolabeled albumin, dextran, or nanocolloid, we used filtered sulfur colloid. (0.1 um). The study confirmed the diagnosis of chylothorax.

Familial resemblance for coronary heart disease risk: the HERITAGE Family Study

The objective of this study was to quantify familial resemblance for coronary heart disease risk in 260 Black and 427 White participants in the HERITAGE Family Study. Coronary heart disease risk was estimated using a coronary heart disease risk index (CHDRI) computed from the revised Framingham Heart Study algorithm, based on age, LDL-cholesterol, HDL-cholesterol, blood pressure, diabetes, and smoking status. Using a familial correlation model to test hypotheses regarding familial aggregation, significant familial resemblance was detected in both Blacks and Whites. There were significant sibling correlations in both Blacks and Whites, while spouse correlations were significant only in the White sample. The maximal heritabilities, which have to be interpreted cautiously in light of negligible parent-offspring correlations, were 34% and 53% in Whites and Blacks, respectively. Thus, the maximal heritability, which includes both genetic and non-genetic sources of variation, is higher in Blacks than Whites, and explains a significant proportion of the total phenotypic variance. The results indicate that risk of coronary heart disease runs along family lines, and common environmental effects are important in explaining the observed familial resemblance.

Routine chest radiographs in pediatric intensive care units

OBJECTIVES

To determine whether interventions were performed based on portable routine morning chest x-rays (CXRs) in pediatric intensive care unit (PICU) patients and to identify patient subgroups for whom the routine CXR is most useful.

DESIGN

Prospective multiinstitutional study. Setting. PICUs of 15 tertiary care hospitals. Patients. PICU patients who received a routine morning CXR were included in the study.

OUTCOME MEASURES

Recorded data included: weight, diagnosis, presence of active cardiopulmonary problems, length of stay, and number and type of devices. The number and types of interventions based on the interpretation of the CXR were recorded.

RESULTS

Five hundred twelve routine CXRs were evaluated. The majority of the routine chest radiographs were obtained on patients who were admitted for cardiovascular disease (195/512; 38%) or respiratory failure (186/512; 36%), and 465/512 of the routine CXRs (91%) were performed on patients with one or more devices. Two hundred thirty-one of the 512 routine CXRs (45%) resulted in 1 or more interventions. One hundred fifty-five of the 284 routine CXRs (55%) obtained in children </=10 kg resulted in one or more interventions, compared with 61/152 (40%) and 15/76 (20%) of routine CXRs obtained in children 10 to 40 kg and >/=40 kg, respectively. The frequency of interventions increased from 19% in children with no devices to >50% in children with 2 or more devices. One or more interventions were performed in 27% of routine CXRs when no active cardiopulmonary problems were present, compared with 51% of routine CXRs when active cardiopulmonary problems were present. Diagnosis and length of intensive care unit stay at the time the routine CXR was obtained did not affect the percentage of CXRs that resulted in interventions.

CONCLUSIONS

Routine CXRs are more likely to result in interventions in the smaller, critically ill child with one or more devices and if active cardiopulmonary problems are present.