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Orah S Platt

Publications and source records attributed to Orah S Platt.

6 recordsLinked to original sources
PubMed2006

Quantitative trait loci for baseline erythroid traits.

A substantial genetic contribution underlies variation in baseline peripheral blood counts. We performed quantitative trait locus/loci (QTL) analyses to identify chromosome (Chr) regions harboring genes influencing the baseline erythroid parameters in F2 intercrosses between NZW/LacJ, SM/J, and C57BLKS/J inbred mice. We identified multiple significant QTL for red blood cell (RBC) count, hemoglobin (Hgb) and hematocrit (Hct) levels, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean cell hemoglobin concentration (CHCM). We identified four RBC count QTL: Rbcq1 (Chr 1, peak LOD score at 62 cM,), Rbcq2 (Chr 4, 60 cM), Rbcq3 (Chr 11, 34 cM), and Rbcq4 (Chr 10, 60 cM). Three MCV QTL were identified: Mcvq1 (Chr 7, 30 cM), Mvcq2 (Chr 11, 6 cM), and Mcvq3 (Chr 10, 60 cM). Single significant loci for Hgb (Hgbq1, Chr 16, 32 cM), Hct (Hctq1, Chr 3, 42 cM), and MCH (Mchq1, Chr 10, 60 cM) were identified. The data support the existence of a common RBC/MCH/MCV locus on Chr 10. Two QTL for CHCM (Chcmq1, Chr 2, 48 cM; Chcmq2, Chr 9, 44 cM) and an interaction between Chcmq2 with a locus on Chr 19 were identified. These analyses emphasize the genetic complexity underlying the regulation of erythroid peripheral blood traits in normal populations and suggest that genes not previously recognized as significantly impacting normal erythropoiesis exist.

Animals↗
PubMed2006

Prevention and management of stroke in sickle cell anemia.

As the overall health of patients with sickle cell anemia (SS) improves and diagnostic techniques become more sensitive, physicians are seeing patients with an increasingly wide range of subtle and not-so-subtle brain injury. The major breakthrough in the field of sickle-related brain injury has been the unprecedented success of transcranial Doppler ultrasonography (TCD) to identify asymptomatic patients at high risk of stroke, coupled with chronic transfusion therapy to prevent it. The evidence for TCD screening and preventive treatment is strong and compelling, but there are still important unanswered questions regarding the implications of "silent infarcts" found in the magnetic resonance images (MRIs) of asymptomatic individuals, and the growing awareness of the burden of neuropsychiatric dysfunction in otherwise apparently healthy individuals.

Anemia, Sickle Cell↗
PubMed2005

Quantitative trait loci for baseline white blood cell count, platelet count, and mean platelet volume.

A substantial genetic contribution to baseline peripheral blood counts has been established. We performed quantitative trait locus/loci (QTL) analyses to identify chromosome (Chr) regions harboring genes influencing the baseline white blood cell (WBC) count, platelet (Plt) count, and mean platelet volume (MPV) in F(2) intercrosses between NZW/LacJ, SM/J, and C57BLKS/J inbred mice. We identified six significant WBC QTL: Wbcq1 (peak LOD score at 38 cM, Chr 1), Wbcq2 (42 cM, Chr 3), Wbcq3 (0 cM, Chr 15), Wbcq4 (58 cM, Chr 1), Wbcq5 (82 cM, Chr 1), and Wbcq6 (8 cM, Chr 14). Three significant Plt QTL were identified: Pltq1 (24 cM, Chr 2), Pltq2 (36 cM, Chr 7), and Pltq3 (10 cM, Chr 12). Two significant MPV QTL were identified, Mpvq1 (62 cM, Chr 15) and Mpvq2 (44 cM, Chr 8). In total, the WBC QTL accounted for up to 31% of the total variance in baseline WBC count, while the Plt and MPV QTL accounted for up to 30% and 49% of the total variance, respectively. These analyses underscore the genetic complexity underlying these traits in normal populations and provide the basis for future studies to identify novel genes involved in the regulation of mammalian hematopoiesis.

Alleles↗
PubMed2005

Genetic influences on peripheral blood cell counts: a study in baboons.

Interperson differences in peripheral blood cell counts in healthy individuals result from genetic and environmental influences. We used multivariate genetic analyses to assess the relative impact of genes and environment on baseline blood cell counts and indices using a pedigreed colony of baboons, an animal with well-documented analogies to human blood physiology. After accounting for age, sex, and weight, we found that genetic influences explain a significant proportion of the remaining variability, ranging from a low of 13.7% for mean corpuscular hemoglobin concentration (MCHC) to a high of 72.4% for red blood cell (RBC) number. Genes influence 38.5% of the variation in baseline white blood cell (WBC) count, a characteristic that correlates with mortality in both the general human population and clinically defined subgroups such as individuals with sickle-cell disease. We examined the interaction between pairs of traits and identified those that share common genetic influences (pleiotropy). We unexpectedly observed that the same gene or group of genes influences both WBC count and mean platelet volume (MPV). We anticipate that this approach will ultimately lead to discovery of novel insights into the biology of related traits, and ultimately identify important genes that affect hematopoiesis.

Animals↗
PubMedDate not supplied

Acquisition of mutans streptococci and caries prevalence in pediatric sickle cell anemia patients receiving long-term antibiotic therapy.

PURPOSE: The purpose of this study was to: (1) evaluate the prevalence of mutans streptococci (MS) and dental caries in sickle cell anemia (SCA) patients receiving long-term prophylactic penicillin therapy; and (2) determine changes in MS colonization and dental caries upon discontinuing the antibiotic. METHODS: Sixty subjects with SCA and 60 age- and race-matched control subjects participated in this study. The SCA subjects were divided into 2 separate age groups: (1) group 1 subjects were under 6 years of age and received penicillin twice a day; and (2) group 2 subjects were 6 to 12 years old and received no daily prophylactic antibiotics, although up to age 6 they had received daily penicillin before it was discontinued. DMFS/dmfs scores for all subjects were obtained through a comprehensive dental examination including bitewing radiographs. Stimulated salivary samples to assess MS levels were obtained on all subjects. Data on medical, dental, fluoride, and dietary history were obtained on all patients through a written parental questionnaire. RESULTS: No group 1 patients had positive cultures for MS. In contrast, 70% of marched controls cultured positively for MS (P<.01). The DMFS/dmfs score for group 1 was 0.21 vs 5.1 for the control group (P<.01). Differences in surfaces affected were also noted, with no group 1 patients having interproximal lesions compared to 47% of control subjects having these lesions (P<.01). Group 2 also had significantly lower levels of MS than matched controls (47% vs 97%, P<.01), although there was no statistically significant difference in caries prevalence or surfaces involved. CONCLUSIONS: These findings demonstrate that long-term penicillin prophylaxis in SCA patients likely prevents the acquisition of MS, resulting in significantly lower caries rates in these patients. This benefit occurs only during active administration of the drug, however, and only delays the acquisition of MS.

Anemia, Sickle Cell↗