Biomedical subjects
Publications and source records attributed to S T Saad.
A 17 year old boy with sickle cell anaemia presented with acute myocardial infarction associated with severe hypoxia and reticulocytopenia. Ischaemic heart disease is rare in sickle cell anemia and in this case it is possible that the acute episode of hypoxia led to myocardial infarction.
This study was designed to compare insulin release during the intravenous glucose tolerance test (GTT) in normal blacks and whites. The study included 14 normal blacks (9 males and 5 females) and 15 normal whites (10 males and 5 females). The index of first phase insulin release (sum of 1 + 3 min insulin levels and total area under the curve for the first 10 min of the GTT) was significantly higher in blacks. The difference is discussed in terms of genetic and acquired traits.
The kidney is involved in virtually all individuals who inherit the sickle cell form of hemoglobin. Though asymptomatic and relatively common, proteinuria in patients with sickle cell anemia (SS) over 40 years old is associated with reduced creatinine clearance. The subclinical increase in urinary albumin is termed microalbuminuria and is a marker of preclinical glomerular damage. The aim of the present study was to determine the presence of microalbuminuria measured by radioimmunoassay in patients with sickle cell disease. The study included 41 patients with SS, 11 patients with hemoglobin SC disease, 4 subjects with S beta-thalassemia and 10 normal controls. All subjects were teenagers or adults. Sixteen SS patients (40%) and 1 SC (9%) and 1 S beta (25%) patient presented mean urinary albumin excretion (UAE) above normal values (30 mg/l. No correlation was observed between UAE and age, creatinine clearance, hemoglobin level or %HbF. These parameters, as well as the presence of leg ulcers, were not significantly different between SS patients with and without UAE above 30 mg/dl. The high prevalence of microalbuminuria in patients with sickle cell anemia indicates that glomerular damage is common. The connection between microalbuminuria and clinical nephropathy has been demonstrated in diabetes and may indicate a sign of early disease rather than a marker for susceptibility. Thus, microalbuminuria may be an early indicator of glomerular damage for patients with sickle cell disease.
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Intravenous glucose tolerance tests (IVGTT) were performed on 9 adults with sickle cell anemia and 15 normal controls. Blood samples were collected before and 1, 3, 5, 10, 20, 30, 40, 50, and 60 min after intravenous glucose infusion and used for glucose and C-peptide assays. The mean C-peptide concentration after glucose infusion was significantly (p less than 0.05) lower for the SCA patients as compared to the controls. No significant differences were observed in the glucose concentration of IVGTT between the two groups. These results suggest an inadequate insulin secretion by the endocrine pancreas in sickle cell anemia or an independent genetic abnormality in linkage disequilibrium with the beta s gene.
We analyzed the frequency of the C282Y and H63D mutations in the HFE gene in 227 individuals from Brazil comprising 71 Caucasians, 91 racially mixed Caucasian African-derived Amerindians (both populations from Southeast Brazil), 85 African-derived subjects (from Northeast Brazil) and 75 Parakanã Indians. Allelic frequency of the mutation C. 845G(A (C282Y) was 1.4% in the Caucasian population, 1.1% in the African-derived population, 1.1% in the racially mixed normal controls and 0% in the Parakanã Indians. In the African-derived population, the C282Y mutation was present on chromosomes bearing the haplotype 6/1h according to Beutler and West (1997). Allelic frequency of the mutation C. 187C(G (H63D) was 16.3% in the Caucasian population, 7.5% in the African-derived population, 9.8% in the racially mixed controls and 0% in the Amerindians. The presence of these mutations in the African-derived population reflects the fact that these subjects may have undergone a non-identified racial admixture in their past history. The absence of both defects in the Amerindians suggests that these mutations have emerged after the migration of Polynesians to America, or that they may not have reached the Polynesian population until after the migration to America had occurred.
Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) variants was carried out in 150 unrelated G6PD deficient blood donors from the region of Campinas, Brazil. By allele specific oligomer hybridization or digestion of exon 4 of the G6PD gene with the restriction endonuclease NlaII, we detected the 202 G-->A mutation in 146 individuals. This mutation was associated with the 376 G-->A substitution and only one haplotype was observed in these individuals. Digestion of exon 6 with the restriction enzyme MboII showed the presence of the Mediterranean variant in three individuals. Haplotype analysis showed, in all three samples, a T at nt 1311 and the C at nt 13 in intron 11, suggesting a European origin of this variant. By SSCP analysis and direct sequencing we detected the mutation nt 1003 G-->A (335 Ala-->Thr) in one blood donor. This mutation was previously described in a boy of Indian ancestry and the variant was denominated G6PD Chatam. The case described here has no Indian ancestry; thus, we presume that the mutations have arisen independently, although we do not know the haplotype of the Indian patient. The haplotype of our case was the most common observed in our population (PvuII, BspHI+, PstI+, 1311C, NlaIII-). Thus, our data indicate that G6PD A- with the 202 G-->A mutation is the most frequent G6PD deficiency in the population of southeastern Brazil. The remaining variants had a Mediterranean origin. These results are in agreement with the origin of the Brazilian population.
This paper reports on a study of the G-6-PD deficiency in Bragança Paulista, São Paulo State, Brazil. A total of 4,621 male blood donors were investigated over a 36-month period. Of these, 80 had the G-6-PD deficiency. Molecular analysis was performed on 70 unrelated G-6-PD deficients through DNA amplification followed by digestion with restriction enzymes and single strand conformation polymorphism analysis (SSCP). In 98.6%, the G-6-PD A- (202 G<--A) mutation was observed through digestion of exon 4 with Nla III. The presence of an uncommon mutation in exon 9 was also observed through SSCP. No case of the Mediterranean variant was observed. These results indicate that the A- (202G<--A) variant, almost exclusive, was introduced into the community not only by individuals of African origin, but also by European immigrants, mainly Italian, Spanish, and Portuguese. The Italian contribution in terms of the G-6-PD Mediterranean variant was smaller than its contribution to beta thalassemia, probably due to the Northern Italian origin of these immigrants.
The red cell distribution width (RDW), and another red cell discriminant function incorporating RDW (MCV2 x RDW/Hgb x 100) were determined in a group of 30 patients with iron deficiency anemia, 30 patients with beta thalassemia trait, and 30 normal subjects. Both RDW and (MCV2 x RDW/Hgb x 100) mean values were significantly higher in iron deficiency anemia than in beta thalassemia trait (p < 0.001). Taking RDW equal or above 21.0 percent among microcytic anemia patients, we identified correctly 90.0 percent of patients with iron deficiency anemia. The sensitivity and specificity of the test were 90.0 percent (IC 95 percent: 0.75-0.98) and 77.0 percent (IC 95 percent: 0.60-0.88), respectively. RDW values below 21.0 percent identified correctly 77.0 percent of beta thalassemia trait with a sensitivity and a specificity of 77.0 percent (IC 95 percent: 0.60-0.88) and 90.0 percent (IC 95 percent: 0.75-0.96), respectively. Taking values of (MCV2 x RDW/Hgb x 100) above and below 80.0 percent as indicative of iron deficiency and beta thalassemia trait, respectively, we identified correctly 97.0 percent of those patients in each group. Both sensitivity and specificity were 97.0 percent (IC 95 percent: 0.84-0.99). These results indicated that the red cell discriminant function incorporating volume dispersion (MCV2 x RDW/Hgb x 100) is a highly sensitive and specific method in the initial screening of patients with microcytic anemia and is better than RDW in differentiating iron deficiency anemia from beta thalassemia trait.
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