RESUMO
OBJECTIVE: To describe h- and g-indices benchmarks in pediatric subspecialties and general academic pediatrics. Academic productivity is measured increasingly through bibliometrics that derive a statistical enumeration of academic output and impact. The h- and g-indices incorporate the number of publications and citations. Benchmarks for pediatrics have not been reported. STUDY DESIGN: Thirty programs were selected randomly from pediatric residency programs accredited by the Accreditation Council for Graduate Medical Education. The h- and g-indices of department chairs were calculated. For general academic pediatrics, pediatric gastroenterology, and pediatric nephrology, a random sample of 30 programs with fellowships were selected. Within each program, an MD faculty member from each academic rank was selected randomly. Google Scholar via Harzing's Publish or Perish was used to calculate the h-index, g-index, and total manuscripts. Only peer-reviewed and English language publications were included. For Chairs, calculations from Google Scholar were compared with Scopus. RESULTS: For all specialties, the mean h- and g-indices significantly increased with academic rank (all P < .05) with the greatest h-indices among Chairs. The h- and g-indices were not statistically different between specialty groups of the same rank; however, mean rank h-indices had large SDs. The h-index calculation using different bibliographic databases only differed by ±1. CONCLUSION: Mean h-indices increased with academic rank and were not significantly different across the pediatric specialties. Benchmarks for h- and g-indices in pediatrics are provided and may be one measure of academic productivity and impact.
Assuntos
Bibliometria , Eficiência , Internato e Residência/estatística & dados numéricos , Pediatria/educação , Benchmarking , Educação de Pós-Graduação em Medicina , Humanos , Publicações , Editoração/estatística & dados numéricosRESUMO
OBJECTIVE: To investigate the role of hematological indices, socioeconomic status, and morbidity in prepubertal growth in homozygous sickle cell (SS) disease from birth to 9 years at the sickle cell clinic of the University Hospital of the West Indies, Kingston, Jamaica. RESULTS: Height increment between 3 and 9 years correlated positively with total haemoglobin at age 7 years in boys but not girls. Attained height and weight at 7 years correlated positively with haemoglobin and fetal haemoglobin in boys but not girls. Only the correlation between haemoglobin and weight showed a significant gender difference. Partial correlation analysis suggested that the effect of haemoglobin was accounted for by the effect of fetal haemoglobin and further analysis indicated that height correlated with F reticulocyte count (a measure of fetal haemoglobin production) in both sexes but not with the ratio of F cells to F reticulocytes (a measure of F cell enrichment). Growth was not significantly related to mean red cell volume, proportional reticulocyte count, alpha thalassaemia, socioeconomic status, or morbidity. CONCLUSION: A high concentration of fetal haemoglobin in boys with SS disease is associated with greater linear growth. It is postulated that in boys, low concentrations of fetal haemoglobin increase haemolysis and hence metabolic requirements for erythropoiesis, putting them at greater risk of poor growth. Differences in the relationship to haemotoloy and growth between boys and girls with SS disease dictate that future analyses of growth take gender into account (AU).x
Assuntos
Humanos , Recém-Nascido , Feminino , Masculino , Anemia Falciforme/sangue , Anemia Falciforme/fisiopatologia , Crescimento/fisiologia , Hemoglobinas/análise , Estatura/fisiologia , Peso Corporal/fisiologia , Estudos de Coortes , Hemoglobina Fetal/análise , Homozigoto , Fatores Sexuais , Classe SocialRESUMO
Five factors have been shown to influence the 20-fold variation of fetal hemoglobin (Hb F) levels in sickle cell anemia (SS): age, sex, the O-globin gene number, á-globin haplotypes, and an X-linked locus that regulates the production of Hb F-containing erythrocytes (F cells), i.e., the F-cell production (FCP) locus. To determine the relative importance of these factors, we studied 257 Jamaican SS subjects from a cohort group identified by newborn screening and from a sib pair study. Linear regression analyses showed that each variable, when analyzed alone, had a significant association with Hb F levels (P < 0.05). Multiple regression analysis, including all variables, showed that the FCP locus is the strongest predictor, accounting for 40 percent of Hb F variation. á-Globin haplotypes, O-globin genes, and age accounted for less than 10 percent of the variation. The association between the á-globin haplotypes and Hb F levels becomes apparent if the influence of the FCP locus is removed by analyzing only individuals with the same FCP phenotype. Thus, the FCP locus is the most important factor identified to date in determining Hb F levels. The variation within each FCP phenotype is modulated by factors associated with the three common á-globin haplotypes and other as yet unidentified factor(s).(AU)
Assuntos
Humanos , Recém-Nascido , Lactente , Pré-Escolar , Criança , Adolescente , Adulto , Hemoglobina Fetal/genética , Anemia Falciforme/genética , Variação Genética , Anemia Falciforme/sangue , Estudos de CoortesRESUMO
Homozygous alpha thalassemia has the beneficial effect in sickle cell anaemia of reducing the hemolytic severity while changing several other hematological parameters. We examined in detail some of these hematological alterations. We find that the broad distribution in erythrocyte density and the large proportion of dense cells associated with sickle cell anaemia are both reduced with co-existing alpha-thalassemia. Measurements of glycosylated hemoglobin levels as a function of cell density indicate that the accelerated increase in cell density, beyond normal cell ageing, in sickle cell anaemia is also reduced with alpha thalassemia. The patients with homozygous alpha-thalassemia and sickle cell disease have slightly lower levels of hemoglobin F than non-thalassemic patients. Examination of hemoglobin F production revealed that the proportion of hemoglobin F containing reticulocytes remained unchanged, as did the proportion of hemoglobin F in cells containing hemoglobin F (F cells). Preferential survival of F cells occurs in sickle cell anaemia, with or without alpha-thalassemia, and the slight difference in hemoglobin F levels appear to reflect differences in numbers of circulating F cells. Thus in sickle cell disease with co-existing alpha-thalassemia, the change in the erythrocyte density profile, possibly due to inhibition of polymerisation-related increases in cell density, explains the hematological improvement.(Summary)
Assuntos
Humanos , Anemia Falciforme/complicações , Anemia Falciforme/genética , Eritrócitos/metabolismo , Talassemia/sangue , Anemia Falciforme/complicações , Anemia Falciforme/genética , Envelhecimento Eritrocítico , Contagem de Eritrócitos , Eritrócitos , Hemoglobina Fetal/genética , Hematócrito , Talassemia/complicações , Talassemia/genéticaRESUMO
Levels of fetal hemoglobin (HbF) bearing reticulocytes (F reticulocytes) range from 2 percent to 50 percent in patients with sickle cell (SS) anemia. To learn whether any portion of such variation in F cell production is regulated by loci genetically separable from the á- globin gene cluster, percentages of F reticulocytes were compared in 59 sib pairs composed solely of SS members, including 40 pairs from Jamaica and 19 from the United States. We reasoned that differences in F reticulocyte levels might arise (1) from any of several kinds of artifact, (2) via half-sib status, or (3) because one or more genes regulating F cell production segregate separately from ás. We minimized the role of artifact by assay of fresh samples from 84 SS individuals, including both members of 38 sib pairs. In 78 of the 84 subjects, serial values for percent F reticulocytes fell within 99.9 percent confidence limits or were alike by t test (Po .05). This left 32 sib pairs for which F reticulocyte levels in each member were reproducible. When sib-sib comparisons were limited to these 32 pairs, percentages of F reticulocytes were grossly dissimilar within 12 Jamaican and 3 American sibships. Within them, the probability that sibs were alike was always ó .005 and usually ó 10 to the 4th power. We next minimized the contribution of half-sibs among Jamaicans by a combination of paternity testing and sib-sib comparison of á-globin region DNA restriction fragment length polymorphisms, especially among discordant pairs. We thereafter concluded that at least seven to eight Jamaican pairs were composed of reproducibly discordant full sibs. There is thus little doubt that there are genes regulating between-patient differences in F cell production that are separate from the á-globin gene cluster. Still unanswered is (1) whether or not these genes are actually linked to á to the s power, (2) why F reticulocyte levels in Americans tend to be lower than in Jamaicans, and (3) whether or not differences in F cell production among SS patients are regulated by several major loci or by only one (AU)
Assuntos
Humanos , Criança , Adolescente , Adulto , Anemia Falciforme/genética , Hemoglobina Fetal/análise , Regulação da Expressão Gênica , Alelos , Anemia Falciforme/sangue , Estudo Comparativo , Família , Reticulócitos/análiseRESUMO
In order to investigate the origin(s) of the mutation(s) leading to the beta S-globin gene in North American populations of African ancestory, we analysed DNA polymorphisms in the beta-globin gene cluster in a large number of both beta A- and beta S-globin gene-bearing chromosomes in U.S. and Jamaican Blacks. We found 16 different haplotypes of polymorphic sites associated with 170 beta S-globin gene-bearing chromosomes. The three most common beta S haplotypes, which account for 151/170 of the beta S-globin gene-bearing chromosomes, are only rarely seen in the chromosomes bearing the beta A-globin gene in these populations (6/47). Two observations suggest multiple origins or interallelic gene conversion, or both, of the beta S mutation. First, the mutation is present in all three beta-globin gene frameworks. Second, the beta S haplotypes can be divided into four groups, each of which cannot be derived from any other by less than two crossing-over events. In summary, our observation of the beta S mutation on 16 different halotypes in African populations can be best explained by (i) a number of simple recombination events 5' to the beta-globin gene and (ii) up to four independent mutations and/or interallelic gene conversions. (AU)