The impact of pedigree structure on heritability estimates for pulse pressure in three studies

OBJECTIVES: Pulse pressure (PP) is a measure of large artery stiffness and has been shown to be an important predictor of cardiovascular morbidity and mortality. The aims of the present study were to investigate the heritability of PP in three studies, the Diabetes Heart Study (DHS), the Insulin Resistance Atherosclerosis Family Study (IRAS FS), and the NHLBI Family Heart Study (FHS), to estimate the residual heritability after inclusion of a common set of covariates, and to investigate the impact of pedigree structure on estimating heritability. METHODS AND RESULTS: DHS is primarily a sibling pair nuclear family study design, while both IRAS FS and FHS have large pedigrees. Heritability estimates of log-transformed PP were obtained using variance component models. After adjusting for age, gender, ethnicity/center, height, diabetes status, and mean arterial pressure (MAP), heritability estimates of PP were 0.40 +/- 0.08 , 0.22 +/- 0.05, and 0.19 +/- 0.03 in DHS, IRAS FS, and FHS, respectively. The heritability estimate from DHS was significantly different from both IRAS FS and FHS (both p values <0.05). A random re-sampling technique (modified bootstrap) was used to explore the heritability in the IRAS FS and FHS data when these pedigrees were trimmed to mimic the DHS pedigree structure. The re-sampling method (mimicking a sibling pair nuclear family design in all studies) yielded PP heritability estimates of 0.37, 0.34, and 0.27 in DHS, IRAS FS, and FHS, respectively. There was no significant difference among the heritability estimates from the three studies based on the re-sampling method. CONCLUSION: We have shown that PP has a moderately heritable component in three different studies. These data illustrate the influence of pedigree structure can have on estimating heritability. Thoughtful comparisons of heritability estimates must consider study design factors such as pedigree structure.     

Segregation analysis of serum uric acid in the NHLBI Family Heart Study

Segregation analysis was performed on the serum uric acid measurements from 523 randomly ascertained Caucasian families from the NHLBI Family Heart Study. Gender-specific standardized residuals were used as the phenotypic variable in both familial correlation and segregation analysis. Uric acid residuals were adjusted for age, age2, age3, body mass index (kg/m2), creatinine level, aspirin use (yes/no), total drinks (per week), HOMA insulin resistance index [(glucose * insulin)/22.5], diuretic use (yes/no), and triglyceride level. Sibling correlations (r=0.193) and parent-offspring correlations (r=0.217) were significantly different from zero, but these two familial correlations were not significantly different from one another. After adjustment for covariates, the heritability estimate for serum uric acid was 0.399. Segregation analysis rejected the "no major gene" model but was unable to discriminate between an "environmental" and a "Mendelian major gene" model. These results support the hypothesis that uric acid is a multifactorial trait possibly influenced by more than one major gene, modifying genes, and environmental factors.     

Region-specific DNA damage by AT-specific DNA-reactive drugs is predicted by drug binding specificity

Bizelesin and adozelesin are DNA-reactive antitumor drugs that alkylate adenines at the 3' ends of their preferred binding sites [5'T(A/T)(4)A3'and 5'(A/T)(3)(-4)A3', respectively]. We used these drugs to examine the determinants for region-specific damage of human genomic DNA. The distribution of bizelesin binding motifs in several regions analyzed "in silico" correlated well with the experimentally determined lesions in these regions assessed by quantitative polymerase chain reaction (QPCR) stop assay. In contrast to the typically low motif density, clusters of potential bizelesin binding sites were found in the matrix-associated regions (MAR domains) of the c-myc and apolipoprotein B (apoB) genes. Accordingly, lesions induced by bizelesin in these domains (2.13 and 7.06 lesions kbp(-1) microM(-1), respectively) markedly exceeded lesions in bulk DNA (0.87 lesions kbp(-1) microM(-1)) or in regions with typically low motif density (e.g., 0.75 and 0.87 lesions kbp(-1) microM(-1) in a beta-globin gene and c-myc origin of replication regions, respectively). Consistent with the more frequent, less localized adozelesin motif, actual lesions induced by adozelesin exceeded by severalfold lesions by bizelesin in four selected regions (within the c-myc and HPRT loci). Whereas adozelesin is likely to affect similar regions as bizelesin, adozelesin's more promiscuous binding probably compromises its relative specificity for such targets. In contrast, findings for bizelesin provide for the first time a proof of principle that a small molecular weight drug can preferentially damage specific regions in cellular DNA. Targeting of critical repetitive sequences, such as AT-rich MAR domains, which allow for clustering of drug binding motif, can be the paradigm for region specificity of small molecular weight agents.     

Differences in growth and water relations among Phaseolus vulgaris cultivars in response to induced drought stress

Relatively little ecophysiological research has been conducted to determine the responses to drought of Phaseolus vulgaris. Four bean cultivars (cvs.) from Brazil, A320, Carioca, Ouro Negro and Xodó were submitted to an imposed water deficit in order to evaluate the importance of some adaptive mechanisms of drought resistance through the analysis of growth parameters, water status, gas exchange and indicators of tolerance mechanisms at the cellular level. During the drought treatment, relative growth rates were more reduced for A320 and Xodó than Carioca and Ouro Negro. A320 closed its stomata very rapidly and complete stomatal closure was obtained at Psi(w)=-0.6 MPa, in contrast to the other cvs. where stomata were fully closed only at Psi(w)=-0.9 MPa. Net assimilation rates were closely related to stomatal conductances. Mechanisms at the cellular level appeared to be mostly important for higher tolerance. Carioca and Ouro Negro, when compared to A320 and Xodó, were characterized by having better drought tolerance mechanisms and higher tissue water retention capacity leading to a better growth under water deficits. The leaf dehydration rates of those cvs. were slow whereas those of the drought sensitive cvs. were rapid. The results were confirmed by the electrolyte leakage test and leaf osmotic potential measurements, which indicated higher membrane resistance and osmotic adjustment in the two tolerant cvs. Carioca and Ouro Negro. It appears from this study that despite being cultivated in the same geographical region, the four cvs. of P. vulgaris displayed somewhat different drought adaptive capacities for prolonged drought during the vegetative phase.     

pH dependence of bone resorption: mouse calvarial osteoclasts are activated by acidosis

We examined the effects of HCO(3)(-) and CO(2) acidosis on osteoclast-mediated Ca(2+) release from 3-day cultures of neonatal mouse calvaria. Ca(2+) release was minimal above pH 7.2 in control cultures but was stimulated strongly by the addition of small amounts of H(+) to culture medium (HCO(3)(-) acidosis). For example, addition of 4 meq/l H(+) reduced pH from 7.12 to 7.03 and increased Ca(2+) release 3.8-fold. The largest stimulatory effects (8- to 11-fold), observed with 15-16 meq/l added H(+), were comparable to the maximal Ca(2+) release elicited by 1,25-dihydroxyvitamin D(3) [1, 25(OH)(2)D(3); 10 nM], parathyroid hormone (10 nM), or prostaglandin E(2) (1 microM); the action of these osteolytic agents was attenuated strongly when ambient pH was increased from approximately 7.1 to approximately 7.3. CO(2) acidosis was a less effective stimulator of Ca(2+) release than HCO(3)(-) acidosis over a similar pH range. Ca(2+) release stimulated by HCO(3)(-) acidosis was almost completely blocked by salmon calcitonin (20 ng/ml), implying osteoclast involvement. In whole mount preparations of control half-calvaria, approximately 400 inactive osteoclast-like multinucleate cells were present; in calvaria exposed to HCO(3)(-) acidosis and to the other osteolytic agents studied, extensive osteoclastic resorption, with perforation of bones, was visible. HCO(3)(-) acidosis, however, reduced numbers of osteoclast-like cells by approximately 50%, whereas 1,25(OH)(2)D(3) treatment caused increases of approximately 75%. The results suggest that HCO(3)(-) acidosis stimulates resorption by activating mature osteoclasts already present in calvarial bones, rather than by inducing formation of new osteoclasts, and provide further support for the critical role of acid-base balance in controlling osteoclast function.     

Inheritance of the Waist‐to‐Hip Ratio in the National Heart,Lung, and Blood Institute Family Heart Study

Objective: Considering that waist‐to‐hip ratio (WHR) is a simple anthropometric measure of obesity and is a better predictor of coronary heart disease than body mass index (BMI), the genetic underpinnings of WHR are of interest. The inheritance pattern of WHR, before and after adjustment for BMI (WHR‐BMI), was investigated in 2713 individuals from 1038 nuclear families in the National Heart, Lung, and Blood Institute Family Heart Study (NHLBI‐FHS). Research Methods and Procedures: Waist and hip measurements were taken twice, and the means of the measurements were used to calculate the WHR. Adjustments for age were carried out separately by sex, using stepwise multiple regression procedures for WHR and WHR‐BMI phenotypes. Segregation analysis was applied using the unified model as implemented in the computer program POINTER. Results: For age‐adjusted WHR, the segregation results suggested an additive major gene that accounts for 35% of the phenotypic variance, and approximately 30% of the sample are homozygous for the “high” genotype. The results for age‐ and BMI‐adjusted WHR were also compatible with a major gene; however, the multifactorial model provided the most parsimonious fit to the data. Discussion: Although the genetic mechanisms for several obesity traits have been studied, tests of Mendelian segregation on this simple anthropometric measure (WHR) have not been reported previously. This study provides evidence for the presence of a major gene for age‐adjusted WHR, suggesting that it is an appropriate trait for further genetic analysis, especially because it has strong predictive value and probably relates biologically to cardiovascular risk.     

Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry,Transparency, and Mechanical Stiffness of the Mouse Lens

The basis for mammalian lens fiber cell organization, transparency, and biomechanical properties has contributions from two specialized cytoskeletal systems: the spectrin-actin membrane skeleton and beaded filament cytoskeleton. The spectrin-actin membrane skeleton predominantly consists of α₂β₂-spectrin strands interconnecting short, tropomyosin-coated actin filaments, which are stabilized by pointed-end capping by tropomodulin 1 (Tmod1) and structurally disrupted in the absence of Tmod1. The beaded filament cytoskeleton consists of the intermediate filament proteins CP49 and filensin, which require CP49 for assembly and contribute to lens transparency and biomechanics. To assess the simultaneous physiological contributions of these cytoskeletal networks and uncover potential functional synergy between them, we subjected lenses from mice lacking Tmod1, CP49, or both to a battery of structural and physiological assays to analyze fiber cell disorder, light scattering, and compressive biomechanical properties. Findings show that deletion of Tmod1 and/or CP49 increases lens fiber cell disorder and light scattering while impairing compressive load-bearing, with the double mutant exhibiting a distinct phenotype compared to either single mutant. Moreover, Tmod1 is in a protein complex with CP49 and filensin, indicating that the spectrin-actin network and beaded filament cytoskeleton are biochemically linked. These experiments reveal that the spectrin-actin membrane skeleton and beaded filament cytoskeleton establish a novel functional synergy critical for regulating lens fiber cell geometry, transparency, and mechanical stiffness.     

18F]-N-Methylspiroperidol: the radioligand of choice for PETT studies of the dopamine receptor in human brain

N-Methylspiroperidol, the amide N-methyl analogue of the neuroleptic spiroperidol, was radiolabeled with fluorine-18, and its distribution in the baboon brain was studied using positron emission transaxial tomography. Stereospecific binding was demonstrated in the striatum (but not in the cerebellum) by pretreatment with (-)- or (+)-butaclamol. The kinetic distribution was similar to that of [18F]spiroperidol, but the absolute striatal uptake (in percent of administered dose) was at least two-fold higher. Analysis of baboon blood at 10 min after injection indicated that less than half of the radioactivity in the plasma was due to unchanged radioligand. Analysis of the metabolic stability of [18F]-N-methylspiroperidol in rat brain for 4 hr indicated that, like [18F]spiroperidol, it is very stable to metabolic transformation in the rat central nervous system. Striatal uptake and retention in the rat was five-fold higher for [18F]-N-methylspiroperidol than for [18F]spiroperidol. These results suggest that [18F]-N-methylspiroperidol is an ideal choice for studies of the dopamine receptor in humans.     

Intra-articular CD1c-expressing myeloid dendritic cells from rheumatoid arthritis patients express a unique set of T cell-attracting chemokines and spontaneously induce Th1, Th17 and Th2 cell activity

Introduction

Myeloid dendritic cells (mDCs) are potent T cell-activating antigen-presenting cells that have been suggested to play a crucial role in the regulation of immune responses in many disease states, including rheumatoid arthritis (RA). Despite this, studies that have reported on the capacity of naturally occurring circulating mDCs to regulate T cell activation in RA are still lacking. This study aimed to evaluate the phenotypic and functional properties of naturally occurring CD1c (BDCA-1)⁺ mDCs from synovial fluid (SF) compared to those from peripheral blood (PB) of RA patients.

Methods

CD1c⁺ mDC numbers and expression of costimulatory molecules were assessed by fluorescence-activated cell sorting (FACS) analysis in SF and PB from RA patients. Ex vivo secretion of 45 inflammatory mediators by mDCs from SF and PB of RA patients was determined by multiplex immunoassay. The capacity of mDCs from SF to activate autologous CD4⁺ T cells was measured.

Results

CD1c⁺ mDC numbers were significantly increased in SF versus PB of RA patients (mean 4.7% vs. 0.6%). mDCs from SF showed increased expression of antigen-presenting (human leukocyte antigen (HLA) class II, CD1c) and costimulatory molecules (CD80, CD86 and CD40). Numerous cytokines were equally abundantly produced by mDCs from both PB and SF (including IL-12, IL-23, IL-13, IL-21). SF mDCs secreted higher levels of interferon γ-inducible protein-10 (IP-10), monokine induced by interferon γ (MIG) and, thymus and activation-regulated chemokine (TARC), but lower macrophage-derived chemokine (MDC) levels compared to mDCs from PB. mDCs from SF displayed a strongly increased capacity to induce proliferation of CD4⁺ T cells associated with a strongly augmented IFNγ, IL-17, and IL-4 production.

Conclusions

This study suggests that increased numbers of CD1c⁺ mDCs in SF are involved in the inflammatory cascade intra-articularly by the secretion of specific T cell-attracting chemokines and the activation of self-reactive T cells.     

Effects of melatonin on acetylsalicylic acid induced gastroduodenal and jejunal mucosal injury

We evaluated the effects of melatonin on acetylsalicylic acid (ASA) induced gastroduodenal and jejunal mucosal injury. We used 40 postpubertal rats divided randomly into five groups of eight animals. The control group consisted of untreated animals. The Mel group was injected intraperitoneally (i.p.) with 5 mg/kg melatonin. The ASA group was injected i.p. with 200 mg/kg ASA. The ASA + Mel group was injected i.p. with 5 mg/kg melatonin 45 min after administering 200 mg/kg ASA i.p. The Mel + ASA group was injected i.p. with 5 mg/kg melatonin 45 min before administering 200 mg/kg ASA i.p. We found no statistically significant differences in mean histopathological scores in the ASA + Mel group compared to the ASA group. ASA caused shortened villi and loss of the apical villus in the duodenum. The histopathological score was increased and villus height was decreased in the ASA group compared to untreated controls. Treatment with melatonin attenuated the histological damage. In the ASA group, occasional areas showed erosion of villi in the jejunum; however, differences in mean histopathological score in ASA group compared to the other groups were not statistically significant. Malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD) activities were measured in stomach, duodenal and jejunum tissue. We found increased MDA activity in both stomach and duodenal tissues in the ASA group compared to the control group (p < 0.05). We found no statistically significant changes in MDA levels in jejunal tissue in the ASA group compared to the control group. We found no change in SOD activity in either stomach or duodenal tissues in the ASA group compared to the control group. We observed decreased SOD activity in jejunal tissue in the ASA group compared to the control group (p < 0.05). We detected no change in GSH activity in stomach, duodenal or jejunal tissues in the ASA group compared to the control group. The stomach damage was less in melatonin treated groups, but the lesions were not completely eliminated. The jejunum in the ASA group retained a nearly normal appearance. We found that melatonin exhibited some healing effects on ASA induced duodenal mucosal injury.