Biomedical subjects

Victor R Gordeuk

Publications and source records attributed to Victor R Gordeuk.

At least 19 recordsLinked to original sources

PubMed2026

Design, rationale, and baseline patient characteristics for the Sickle Cell Disease and CardiovAscular Risk-Red cell Exchange (SCD-CARRE) trial.

BACKGROUND: Despite wide utilization of automated red blood cell exchange (RBCX) transfusion in adult patients with sickle cell disease (SCD), no consensus or quality efficacy data exist on its use. The Sickle Cell Disease and CardiovAscular Risk- Red cell Exchange (SCD-CARRE) trial tests the hypothesis that an automated chronic RBCX transfusion strategy reduces acute health care encounters and death while improving quality of life and end-organ function (cardiac, pulmonary and renal) in participants with SCD that are at high risk of death. METHODS: Adult patients with SCD with elevated tricuspid regurgitant jet velocity (TRV) and/or chronic kidney disease were considered to be at high risk of death and were randomly assigned to RBCX plus standard of care vs standard of care alone. Participants assigned to RBCX received 12 months of exchange transfusions to maintain target pretransfusion hemoglobin S% < 30%, post-transfusion hemoglobin S% < 20%, and post-transfusion hemoglobin concentration ≥10 g/dL. All study participants were managed according to NHLBI/ASH/ATS Expert Panel guidelines. The primary endpoint was the number of SCD acute health care encounters or death over 13 months. Secondary endpoints included measures of cardiovascular and renal function, exercise capacity, patient reported outcomes (all collected at baseline, and months 4, 8, and 12), and transfusion-related adverse events (collected monthly). RESULTS: Between 2020 and 2025, the SCD-CARRE trial randomized 173 participants at 23 sites across 3 countries. Enrolled participants had mean (SD) age of 45.8 (11.8) years and 54% were female. At baseline, participants had average TRV of 2.8 (0.5) m/s such that 45.9% had a TRV between 2.5 to 2.9 m/sec and 28.1% had a TRV ≥ 3.0 m/sec. The median (Q1, Q3) eGFR in this cohort was 60 (36, 110) mL/min/1.73 m2. The median (Q1, Q3) 6-minute walk test distance was 375 meters (309, 439), the median daily steps were 3,728 (2,187, 5,821), and participants experienced a median (Q1, Q3) of 2 (1, 5) pain episodes in the year prior to randomization. The trial results are pending. CONCLUSIONS: The SCD-CARRE trial successfully enrolled a cohort of n = 173 adults with SCD. This study highlights a rationale to evaluate the effect of automated chronic RBCX transfusion strategy plus standard of care as compared to standard of care alone in SCD patients at high risk of death with a focus on patient centered outcomes, preservation of cardiovascular function, end-organ complications and death. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT04084080, https://clinicaltrials.gov/study/NCT04084080.

Adult↗

PubMed2024

Whole-genome sequencing in 333,100 individuals reveals rare non-coding single variant and aggregate associations with height.

The role of rare non-coding variation in complex human phenotypes is still largely unknown. To elucidate the impact of rare variants in regulatory elements, we performed a whole-genome sequencing association analysis for height using 333,100 individuals from three datasets: UK Biobank (N = 200,003), TOPMed (N = 87,652) and All of Us (N = 45,445). We performed rare ( < 0.1% minor-allele-frequency) single-variant and aggregate testing of non-coding variants in regulatory regions based on proximal-regulatory, intergenic-regulatory and deep-intronic annotation. We observed 29 independent variants associated with height at P < after conditioning on previously reported variants, with effect sizes ranging from -7cm to +4.7 cm. We also identified and replicated non-coding aggregate-based associations proximal to HMGA1 containing variants associated with a 5 cm taller height and of highly-conserved variants in MIR497HG on chromosome 17. We have developed an approach for identifying non-coding rare variants in regulatory regions with large effects from whole-genome sequencing data associated with complex traits.

Humans↗

PubMed2006

Phosphorylation of HIV-1 Tat by CDK2 in HIV-1 transcription.

BACKGROUND: Transcription of HIV-1 genes is activated by HIV-1 Tat protein, which induces phosphorylation of RNA polymerase II (RNAPII) C-terminal domain (CTD) by CDK9/cyclin T1. Earlier we showed that CDK2/cyclin E phosphorylates HIV-1 Tat in vitro. We also showed that CDK2 induces HIV-1 transcription in vitro and that inhibition of CDK2 expression by RNA interference inhibits HIV-1 transcription and viral replication in cultured cells. In the present study, we analyzed whether Tat is phosphorylated in cultured cells by CDK2 and whether Tat phosphorylation has a regulatory effect on HIV-1 transcription. RESULTS: We analyzed HIV-1 Tat phosphorylation by CDK2 in vitro and identified Ser16 and Ser46 residues of Tat as potential phosphorylation sites. Tat was phosphorylated in HeLa cells infected with Tat-expressing adenovirus and metabolically labeled with 32P. CDK2-specific siRNA reduced the amount and the activity of cellular CDK2 and significantly decreased phosphorylation of Tat. Tat co-migrated with CDK2 on glycerol gradient and co-immunoprecipitated with CDK2 from the cellular extracts. Tat was phosphorylated on serine residues in vivo, and mutations of Ser16 and Ser46 residues of Tat reduced Tat phosphorylation in vivo. Mutation of Ser16 and Ser46 residues of Tat reduced HIV-1 transcription in transiently transfected cells. The mutations of Tat also inhibited HIV-1 viral replication and Tat phosphorylation in the context of the integrated HIV-1 provirus. Analysis of physiological importance of the S16QP(K/R)19 and S46YGR49 sequences of Tat showed that Ser16 and Ser46 and R49 residues are highly conserved whereas mutation of the (K/R)19 residue correlated with non-progression of HIV-1 disease. CONCLUSION: Our results indicate for the first time that Tat is phosphorylated in vivo; Tat phosphorylation is likely to be mediated by CDK2; and phosphorylation of Tat is important for HIV-1 transcription.

Cyclin-Dependent Kinase 2↗

PubMed2006

The association of serum ferritin and transferrin receptor concentrations with mortality in women with human immunodeficiency virus infection.

BACKGROUND AND OBJECTIVES: Whether degree of iron stores influences progression of human immunodeficiency virus (HIV) disease is controversial. We studied the relationship of indirect measures of iron stores with mortality in highly active antiretroviral therapy (HAART)-naive participants from the Women's Interagency HIV Study. DESIGN AND METHODS: One hundred and fifty-eight HIV-infected women who died before July 1996 were individually matched by CD4+ cell count (within +/- 50 cells/mL) and HIV RNA level (within +/- 0.50 log10 copies/mL) to 154 controls. Serum ferritin and transferrin receptor concentrations were measured in 151 pairs of women. Results. Using multivariable conditional logistic regression models that were adjusted for self-reported antiretroviral therapy use, age, smoking status, ethnicity, hemoglobin concentration, C-reactive protein and aspartate amino transferase, a log10 increase in baseline serum ferritin concentration was associated with a 1.67-fold increase in the odds of death (95% CI: 0.98, 2.86) and a one-unit decrease in transferrin receptor to log10 ferritin ratio was associated with a 1.12-fold (95% CI: 1.01, 1.23) increase in the odds of death. INTERPRETATIONS AND CONCLUSIONS: In this study, higher indirect measures of iron status were associated with reduced survival among HAART-naive HIV-infected women. Additional prospective studies with data on direct measures of iron status along with randomized trials are needed to elucidate the current equipoise over whether iron supplementation is beneficial by preventing anemia or harmful by increasing iron stores in HIV-infected women.

CD4 Lymphocyte Count↗

PubMed2006

A critical role for the host mediator macrophage migration inhibitory factor in the pathogenesis of malarial anemia.

The pathogenesis of malarial anemia is multifactorial, and the mechanisms responsible for its high mortality are poorly understood. Studies indicate that host mediators produced during malaria infection may suppress erythroid progenitor development (Miller, K.L., J.C. Schooley, K.L. Smith, B. Kullgren, L.J. Mahlmann, and P.H. Silverman. 1989. Exp. Hematol. 17:379-385; Yap, G.S., and M.M. Stevenson. 1991. Ann. NY Acad. Sci. 628:279-281). We describe an intrinsic role for macrophage migration inhibitory factor (MIF) in the development of the anemic complications and bone marrow suppression that are associated with malaria infection. At concentrations found in the circulation of malaria-infected patients, MIF suppressed erythropoietin-dependent erythroid colony formation. MIF synergized with tumor necrosis factor and gamma interferon, which are known antagonists of hematopoiesis, even when these cytokines were present in subinhibitory concentrations. MIF inhibited erythroid differentiation and hemoglobin production, and it antagonized the pattern of mitogen-activated protein kinase phosphorylation that normally occurs during erythroid progenitor differentiation. Infection of MIF knockout mice with Plasmodium chabaudi resulted in less severe anemia, improved erythroid progenitor development, and increased survival compared with wild-type controls. We also found that human mononuclear cells carrying highly expressed MIF alleles produced more MIF when stimulated with the malarial product hemozoin compared with cells carrying low expression MIF alleles. These data suggest that polymorphisms at the MIF locus may influence the levels of MIF produced in the innate response to malaria infection and the likelihood of anemic complications.

Alleles↗

PubMed2006

Association of serum transferrin receptor concentration with markers of inflammation in Zimbabwean children.

BACKGROUND: Clinical studies have shown that degree of erythropoiesis, the hypoxic response, and iron status each independently influences transferrin receptor concentration, but there is conflicting information regarding the effect of inflammation on transferrin receptor expression. SUBJECTS AND METHODS: Levels of hemoglobin, reticulocytes, serum ferritin, transferrin receptors and inflammatory markers (C-reactive protein, interleukin-6 and neutrophils) were determined in 208 Zimbabwean children 10 ng/mL that adjusted for erythropoiesis with log(10) reticulocyte count, the hypoxic response with hemoglobin concentration and iron status with log(10) ferritin concentration, positive correlations were found between log(10) transferrin receptor concentration and log(10) C-reactive protein concentration (P=0.012), log(10) interleukin-6 concentration (P=0.011) and log(10) neutrophil count (P=0.013). These models predict that, with a baseline transferrin receptor concentration in the upper normal range of 8.0 mg/L and holding hemoglobin concentration and reticulocyte count constant, an increase from 1 to 10 mg/L in C-reactive protein is associated with a rise of 1.6 mg/L in transferrin receptor (95% C.I. 0.3-3.0 mg/L), an increase from 0.5-to-5.0 pg/mL in interleukin-6 with a rise of 1.9 mg/L (0.4-3.7 mg/L), and an increase from 2000 to 20,000/microL in neutrophil count with a rise of 3.6 mg/L (0.7-7.5 mg/L). CONCLUSION: Our results suggest that inflammation leads to an increase in circulating transferrin receptor concentration that is independent of the degree of erythropoiesis, the hypoxic response and iron status.

Biomarkers↗

PubMed2006

Circumstances of death in adult sickle cell disease patients.

The purpose of the study was to analyze clinical and/or autopsy findings at the time of death among adults with sickle cell disease (SCD) at Howard University in Washington, DC over a 25-year period. A single physician recorded circumstances of death among 141 adult SCD patients he treated and knew well from 1976 to 2001. These findings were determined by autopsy report and/or clinical assessment. In a subset of 31 patients, autopsy records were reviewed for reports of iron deposition in liver and heart and of organ pathology. One hundred and fourteen (80.9%) of the patients had SS phenotype and 66 (46.8%) were female. The mean +/- SD age at death was 36 +/- 11 years. Leading circumstances of death included pulmonary hypertension (PHT) (26.2%), sudden death (23.4%), renal failure (22.6%), infection (18.4%), thromboembolism (14.9%), cardiac diagnoses (12.0%), cirrhosis (11.3%), pneumonia or acute chest syndrome (9.9%), bleeding (7.8%), and iron overload (7.0%). When circumstances of deaths that occurred after 1991 (n = 69) were compared to those that occurred in 1991 or earlier (n = 72), PHT (36.2% vs. 16.6%; P < 0.01) was significantly more common in 1992 or later. Significant associations were found between PHT and thromboembolism and between cirrhosis and iron overload. In this proportional mortality study of adults with SCD, PHT was the leading finding at the time of death. Thromboembolism was associated with PHT, and iron overload was associated with cirrhosis.

Adult↗

PubMed2006

Liver diseases in the hemochromatosis and iron overload screening study.

BACKGROUND AND AIMS: The Hemochromatosis and Iron Overload Screening (HEIRS) Study screened 101,168 primary care participants for iron overload with serum transferrin saturation (TS), ferritin, and C282Y and H63D mutations of the HFE gene. METHODS: All C282Y homozygotes and participants with an increased TS (>45% women, >50% men) and serum ferritin level (> 200 microg/L women, >300 microg/L men) were recalled for a clinical history and physical examination, and blood tests including alanine transaminase (ALT) and aspartate transaminase levels. Hepatitis B surface antigen and anti-hepatitis C virus were measured if the ALT level was increased (>31 IU/L in women, >40 IU/L in men). RESULTS: In the group of participants selected to return for clinical examination because of increased TS and ferritin levels, ALT increases and anti-hepatitis C virus were found in 95 of 284 (33%) African Americans, 50 of 466 (11%) Asian and Pacific Islanders, 21 of 120 (18%) Hispanics, and 40 of 477 (8.4%) Caucasians. ALT increases and hepatitis B surface antigen were detected in 24 of 466 (5%) Asian and Pacific Islanders, 10 of 284 (3.5%) African Americans, 3 of 120 (2.5%) Hispanics, and 2 of 477 (.42%) Caucasians. Of 86 liver biopsy specimens obtained for clinical purposes, 53 were reviewed by a single study pathologist. Liver fibrosis (stage 3 or 4) was present in 2 of 11 (18.2%) C282Y homozygotes that underwent central review and 2 of 302 (.66%) C282Y homozygotes attending the clinical examination. CONCLUSIONS: Screening for iron overload with ferritin and TS detects persons with viral hepatitis and other types of liver disease. A minimum of .66% C282Y homozygotes have liver fibrosis.

Adult↗

PubMed2006

Mixture models of serum iron measures in population screening for hemochromatosis and iron overload.

Homozygosity for the C282Y mutation of the hemochromatosis gene on chromosome 6p (HFE) is a common genetic trait that increases susceptibility to iron overload. The authors describe and apply methodology developed for the analysis of phenotypic and genotypic data from 46,136 non-Hispanic Caucasians, a subset of the multi-ethnic cohort enrolled in the Hemochromatosis and Iron Overload Screening (HEIRS) Study. For analysis of the distribution of transferrin saturation (TS), mixtures of normal distributions were considered and the expectation-maximization (EM) algorithm was applied for parameter estimation. Maximized log-likelihoods were compared, and significance was assessed by resampling. Sensitivity, specificity, and predictive values from the modeled subpopulations were compared with the actual observed genotypes for C282Y and H63D mutations in the HFE gene. A strong association between HFE genotype and TS subpopulations was found in these data collected from different geographic regions, confirming the external validity of the statistical approach when applied to population-based data. It was concluded that mixture modeling of phenotypic data may provide a clinical guide for screening with gender-specific thresholds to identify potential samples for genetic testing.

Adult↗

PubMed2006

Vascular complications in Chuvash polycythemia.

Chuvash polycythemia is characterized by a homozygous 598C> T germline mutation in the von Hippel-Lindau gene ( VHL), upregulation of hypoxia-inducible factor-1alpha during normoxia, and resulting augmentation of erythropoietin and several other hypoxia-controlled genes. Although endemic to the Chuvash population of Russia, this mutation occurs worldwide and usually originates from a single ancient event. Matched-cohort and case-control analyses have shown that VHL 598C> T homozygosity is associated with lower peripheral blood pressures, varicose veins, vertebral hemangiomas, lower white blood cell and platelet counts, and elevated serum concentrations of vascular endothelial growth factor and plasminogen activator inhibitor-1. These studies have also shown associations with arterial and venous thrombosis, major bleeding episodes, cerebral vascular events, and premature mortality. Spinocerebellar hemangioblastomas, renal carcinomas, and pheochromocytomas typical of classical VHL tumor predisposition syndrome have not been found, and no increased risk of cancer has been demonstrated. Retrospective analyses among patients with Chuvash polycythemia have not shown benefit for therapy with phlebotomy or aspirin, but these and other modes of therapy should be studied prospectively. Further investigation of the vascular complications of Chuvash polycythemia may increase our fundamental knowledge of thrombophilia, bleeding diatheses, and protection from cancer.

Aspirin↗

PubMed2006

Endothelin-1, vascular endothelial growth factor and systolic pulmonary artery pressure in patients with Chuvash polycythemia.

BACKGROUND AND OBJECTIVES: Endothelin-1 has been associated with development of hypoxia-related pulmonary hypertension and vascular endothelial growth factor (VEGF) with protection from this complication. In Chuvash polycythemia, homozygous germline von Hippel-Lindau (VHL) 598C->T leads to up-regulation during normoxia of hypoxia inducible factor-1a and several hypoxia-controlled genes including erythropoietin and VEGF. We postulated that endothelin-1 and pulmonary artery pressure may be elevated in Chuvash polycythemia. DESIGN AND METHODS: Systolic pulmonary artery blood pressure was estimated by Doppler echocardiography and plasma concentrations of endothelin-1, VEGF and erythropoietin were determined in 14 patients with Chuvash polycythemia and 14 controls. Results. Plasma endothelin-1 (p=0.010), VEGF (p=0.022) and erythropoietin (p<0.0005) concentrations and Doppler-estimated systolic pulmonary artery pressures (p<0.0005) were higher in the patients while systolic systemic blood pressures were lower (p=0.001). Five (36%) patients and no controls had mild pulmonary hypertension defined as systolic pulmonary artery pressure (c) 35 mmHg. Among the patients with Chuvash polycythemia, the trends of association of estimated pulmonary artery pressure with plasma concentrations of endothelin-1 (R = +0.236), VEGF (R = -0.389) and erythropoietin (R = +0.220) were not statistically significant. INTERPRETATIONS AND CONCLUSIONS: Estimated systolic pulmonary artery pressure and plasma concentrations of endothelin-1 and VEGF are increased in patients with Chuvash polycythemia patients. The lack of significant associations of estimated systolic pulmonary artery pressure with plasma endothelin-1 and VEGF levels could conceivably be due to the small sample size. Further studies are indicated, especially in view of the reported efficacy of endothelin-1 receptor blockers in treating hypoxia-associated pulmonary hypertension.

Altitude↗

PubMed2005

The celestial fire of conscience.

Explore the source record for details and available documents.

Conscience↗

PubMed2005

Nuclear targeting of protein phosphatase-1 by HIV-1 Tat protein.

Transcription of human immunodeficiency virus (HIV)-1 genes is activated by HIV-1 Tat protein, which induces phosphorylation of the C-terminal domain of RNA polymerase-II by CDK9/cyclin T1. We previously showed that Tat-induced HIV-1 transcription is regulated by protein phosphatase-1 (PP1). In the present study we demonstrate that Tat interacts with PP1 and that disruption of this interaction prevents induction of HIV-1 transcription. We show that PP1 interacts with Tat in part through the binding of Val36 and Phe38 of Tat to PP1 and that Tat is involved in the nuclear and subnuclear targeting of PP1. The PP1 binding mutant Tat-V36A/F38A displayed a decreased affinity for PP1 and was a poor activator of HIV-1 transcription. Surprisingly, Tat-Q35R mutant that had a higher affinity for PP1 was also a poor activator of HIV-1 transcription, because strong PP1 binding competed out binding of Tat to CDK9/cyclin T1. Our results suggest that Tat might function as a nuclear regulator of PP1 and that interaction of Tat with PP1 is critical for activation of HIV-1 transcription by Tat.

Amino Acid Motifs↗

PubMed2005

Hemochromatosis and iron-overload screening in a racially diverse population.

BACKGROUND: Iron overload and hemochromatosis are common, treatable conditions. HFE genotypes, levels of serum ferritin, transferrin saturation values, and self-reported medical history were studied in a multiethnic primary care population. METHODS: Participants were recruited from primary care practices and blood-drawing laboratories. Blood samples were tested for transferrin saturation, serum ferritin, and C282Y and H63D mutations of the HFE gene. Before genetic screening, participants were asked whether they had a history of medical conditions related to iron overload. RESULTS: Of the 99,711 participants, 299 were homozygous for the C282Y mutation. The estimated prevalence of C282Y homozygotes was higher in non-Hispanic whites (0.44 percent) than in Native Americans (0.11 percent), Hispanics (0.027 percent), blacks (0.014 percent), Pacific Islanders (0.012 percent), or Asians (0.000039 percent). Among participants who were homozygous for the C282Y mutation but in whom iron overload had not been diagnosed (227 participants), serum ferritin levels were greater than 300 mug per liter in 78 of 89 men (88 percent) and greater than 200 microg per liter in 79 of 138 women (57 percent). Pacific Islanders and Asians had the highest geometric mean levels of serum ferritin and mean transferrin saturation despite having the lowest prevalence of C282Y homozygotes. There were 364 participants in whom iron overload had not been diagnosed (29 C282Y homozygotes) who had a serum ferritin level greater than 1000 microg per liter. Among men, C282Y homozygotes and compound heterozygotes were more likely to report a history of liver disease than were participants without HFE mutations. CONCLUSIONS: The C282Y mutation is most common in whites, and most C282Y homozygotes have elevations in serum ferritin levels and transferrin saturation. The C282Y mutation does not account for high mean serum ferritin levels and transferrin saturation values in nonwhites.

Arthritis↗

PubMed2005

An iron regulatory-like protein expressed in Plasmodium falciparum displays aconitase activity.

Plasmodium falciparum iron regulatory-like protein (PfIRPa) has homology to both mammalian iron regulatory proteins and aconitases and is capable of binding RNA iron response elements. We examined the subcellular localization of PfIRPa and its enzymatic properties at low oxygen tension. Differential digitonin permeabilization of isolated trophozoites with subsequent Western blot analysis suggests that the localization of PfIRPa is predominantly in the membranous compartments of the parasite, such as the mitochondrion. Immunofluorescence analysis showed that PfIRPa colocalizes with heat shock protein 60 (Hsp60), a mitochondrial marker, and is also present in the parasitic cytosol/food vacuole. Under conditions favoring the formation of an iron-sulfur cluster, recombinant PfIRPa (rPfIRPa) had aconitase activity as detected by a colorimetric NADPH-MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. As assessed by the hydration of cis-aconitate spectrophotometrically at 240 nm, rPfIRPa had high affinity for cis-aconitate (Km=3.5 microM) but a low turnover number (Kcat= 3.3 s(-1)). The overall catalytic efficiency (Kcat/Km) of rPfIRPa was similar in magnitude to human cytosolic IRP1/aconitase and human mitochondrial aconitase. PfIRPa immunoprecipitated from parasite lysates also had aconitase activity, as assessed by an MTT-based assay. Our results provide evidence that PfIRPa localizes in the mitochondrion and in the cytosol/food vacuole and is able to demonstrate aconitase activity. Further understanding of the role of PfIRPa/aconitase in the regulation of P. falciparum homeostasis may contribute towards the development of novel antimalarial strategies against plasmodial species.

Aconitate Hydratase↗

PubMed2005

Initial screening transferrin saturation values, serum ferritin concentrations, and HFE genotypes in whites and blacks in the Hemochromatosis and Iron Overload Screening Study.

We compared initial screening data of 44,082 white and 27,124 black Hemochromatosis and Iron Overload Screening (HEIRS) Study participants. Each underwent serum transferrin saturation (TfSat) and ferritin (SF) measurements without regard to fasting, and HFE C282Y and H63D genotyping. Elevated measurements were defined as: TfSat more than 50% (men), more than 45% (women); and SF more than 300 ng/ml (men), more than 200 ng/ml (women). Mean TfSat and percentages of participants with elevated TfSat were significantly greater in whites than in blacks. Mean SF and percentages of participants with elevated SF were significantly greater in blacks than in whites. TfSat and SF varied by gender and age in whites and blacks. Prevalences of genotypes that included either C282Y or H63D were significantly greater in whites than in blacks. The prevalence of elevated TfSat and SF plus genotypes C282Y/C282Y, C282Y/H63D, or H63D/H63D was 0.006 in whites and 0.0003 in blacks. Among whites with HFE C282Y homozygosity, 76.8% of men and 46.9% of women had elevated TfSat and SF values. Three black participants had HFE C282Y homozygosity; one had elevated TfSat and SF values. Possible explanations for differences in TfSat and SF in whites and blacks and pertinence to the detection of hemochromatosis, iron overload, and other disorders with similar phenotypes are discussed.

Adult↗

PubMed2005

Effect of ferroportin Q248H polymorphism on iron status in African children.

BACKGROUND: Iron deficiency is common in African children, but genetic variations affecting susceptibility have not been identified. The Q248H mutation in ferroportin, a cellular iron exporter regulated by iron status and inflammation, may be associated with high iron stores in African adults. OBJECTIVE: The study examined the prevalence of iron deficiency in African children in an area where malaria transmission is low to absent and investigated whether ferroportin Q248H provides protection from iron deficiency. DESIGN: Complete blood counts, serum markers of iron status and inflammation, and ferroportin Q247H were measured in 208 preschool children in Harare, Zimbabwe. Iron deficiency was defined by serum ferritin and C-reactive protein (CRP) concentrations (definition 1) or by ferritin and the ratio of transferrin receptor to log10 ferritin (definition 2). RESULTS: Q248H was present in 40 children (38 heterozygotes, 2 homozygotes), elevated CRP was present in 26 (12.5%), and iron deficiency was present in 50 (24.0%) (definition 1) or 55 (26.4%) (definition 2). The interaction between ferroportin Q248H and CRP was significant for ferritin concentrations (P = 0.027) in a 2-factor analysis of variance model. With elevated CRP, the estimated geometric mean (SE range) ferritin concentration was 74 (52-106) microg/L for Q248H heterozygotes but 24 (20-30) microg/L for wild-type subjects (P = 0.016). With normal CRP, the ferritin concentration was 16 (14-19) microg/L whether or not the mutation was present. After adjustment for age and weight-for-height z score, the odds ratio (OR) for iron deficiency in Q248H heterozygotes was not significant according to definition 1 (OR: 0.53; 95% CI: 0.18, 1.40; P = 0.222) or definition 2 (OR: 0.39; 95% CI: 0.14, 1.07; P = 0.068). CONCLUSIONS: Any effect of Q248H in protecting against iron deficiency may be observable in children exposed to repeated inflammatory conditions. Further studies of iron status and ferroportin Q248H in African children are needed.

Analysis of Variance↗

PubMed2005

The impact of body mass index on pulse pressure in obesity.

OBJECTIVE: Pulse pressure, a marker of arterial vascular properties, has been linked to cardiovascular diseases and complications. This study examined the impact of excess body mass and cardiovascular disease risk factors on pulse pressure (PP). DESIGN: Cross-sectional and prospective study. METHODS: Baseline data consist of 219 obese African Americans, with mean +/- SD age of 46.8 +/- 10.9 years enrolled in a diet and exercise program of weight reduction. A non-invasive monitoring device was used to acquire 24 hourly ambulatory blood pressures. Pulse pressure was calculated as the difference between the average 24-h systolic and diastolic blood pressure and studied as a continuous variable and according to quartiles. The cross-sectional association of pulse pressure with body mass index (BMI) was examined using multivariate linear regression and proportional odds models that controlled for cardiovascular disease risk factors. In addition, we examined prospectively, in 36 participants, the effect of weight loss on pulse pressure, using the Wilcoxon signed ranked test. RESULTS: At baseline, a 5 kg/m2 increase in BMI was independently associated with a 35% risk [relative risk (RR) = 1.35, confidence interval (CI) = 1.10-1.65, P < 0.01] in the general study population and 19% (RR = 1.19, CI = 1.07-1.56, P = 0.04) in obese normotensives for increasing PP by one quartile after adjustment for other significant variables. After 3 months of diet and exercise intervention, BMI decreased by an average of 10.6% (P < 0.01) and resulted in an 8.8% (P < 0.01) reduction in PP. CONCLUSIONS: In the context of obesity, increasing BMI is independently associated with decreasing arterial compliance, as reflected in PP. This association highlights the potential value to cardiovascular health of any reduction in body weight in obese individuals.

Adult↗