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Renal acidification in sickle cell trait.

Nine sickle cell trait and nine control subjects underwent six-hour ammonium chloride acid loading. Maximal urine osmolality and renal hemodynamics were studied separately. Base line arterial pH, carbon dioxide pressure (Pco2), and [HCO3] were normal and comparable in the two groups. After ammonium chloride loading, urine pH decreased to 5.3 or less in all, and maximal excretion of ammonium and titratable and net acid was comparable as was urine minus blood Pco2 after bicarbonate loading. The ammonium chloride acidosis caused a small decrease in red blood cell 2,3-diphosphoglycerate levels but no alteration in oxygen pressure at 50% saturation at pH 7.4, sickling, or adverse effects. Control and sickle cell trait subjects had comparable renal hemodynamics but maximal urine osmolality was lower in sickle-cell trait subjects. Adults with sickle cell trait have diminished renal concentrating ability and normal renal acidification and hemodynamics.

Acidosis, Renal Tubular↗

[Defects in peroxidation of erythrocyte phospholipids in sickle cell trait].

The sickle cell disease pathophysiology is provided by several events including deoxyhemoglobin S polymerization and hemorrheological troubles. Classically, such disorders have been known to concern only the homozygous SS and heterozygous SC profiles. However, troubles are more and more described since early years in the sickle cell trait patients and the pathogenesis factors are unknown. Our study focussed on phospholipids which are the basic and functional constituent elements of erythrocyte plasmic membrane. Assaying the membrane lipids extracted by Folch method and lipid standards (cholesterol, phosphatidic acid, lysophosphatidyl-choline, phosphatidyl-choline, lysophosphatidyl-ethanolamine, phosphatidyl-ethanolamine, sphingomyelin) was carried out by HPLC among 91 sickle cell trait patients as compared to 78 healthy subjects. The main abnormalities observed were an empoverishement in phosphatidyl-choline contrasting with an accumulation of membrane lysophosphatidyl-choline, lysophosphatidyl-ethanolamine, phosphatidic acid and sphingomyelin in sickle cell patients. These results suggest that sickle cell trait harmlessness is not actual. The accumulation of lysophosphatidyl-choline, by its cytolytic biomembrane perturbing properties, predispose therefore the sickled red cell to the haemolysis phenomena and allow to forecast deeper disturbances among homozygous subjects. These morbid disorders attributable to lipid peroxidation would justify an antioxidant treatment during the sickle cell disease.

Erythrocytes↗

A comparison of the physical and intellectual development of black children with and without sickle-cell trait.

Sickle-cell trait, a condition present in 7% to 9% of the United States Black population, is usually considered to be a clinically benign condition. However, there is increasing evidence to indicate the contrary, that is, the clinical pathophysiology is variable, ranging from a benign condition in most cases to a relatively few cases of severe pathological involvement. Physical and intellectual growth measures were taken on 19 children with sickle-cell trait (12 boys and 7 girls) from a large study of Black same-sex twin pairs from Philadelphia, Pennsylvania, and compared to measures taken of a sample of normal Black children from 155 monozygotic and dizygotic same-sex twin pairs. Sickle-cell trait carriers were found to weigh less, have smaller upper arm circumference lesser skinfold thickness, and showed less mature skeletal age, differing significantly from normal children. Sickle-cell carriers tended to score lower on four of five intellectual measures, scoring one fifth to one third of a standard deviation lower than normal children.

Adolescent↗

Effects of physical stress on peroxide scavengers in normal and sickle cell trait erythrocytes.

Sickle cell trait subjects are potentially at risk with microvascular complications frequently associated with high altitude and extreme exertion. Studies conducted in our laboratory suggest that exposure of sickle cell trait subjects to treadmill exercise resulted in an increase not only in the susceptibility of red blood cells to oxidation but also in the density of RBC membrane. The trend of increased susceptibility of red cells to oxidation as a consequence of exercise was associated with relatively excessive production of H2O2, inefficient breakdown of H2O2 by GSH-Px- and catalase-catalyzed reactions, and inability/failure to show a transitory increase in the activity of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-generating enzymes.

Adult↗

Nocturnal autonomic nervous system activity impairment in sickle cell trait carriers.

Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal haemoglobin (Hb) and marked by the heterozygous presence of HbA and HbS. Some studies have suggested that SCT carriers might be prone to vascular alterations, cardiac ischaemia and arrhythmias leading, in some subjects, to sudden death. It is well known that a loss or a disequilibrium of autonomic activity are powerful predictors of sudden cardiac death. We hypothesized that SCT subjects might exhibit alterations in the activity of the autonomic nervous system that could constitute further risk factors for cardiac complications. Resting haemorheological parameters (eta(b), blood viscosity; eta(p), plasma viscosity; Hct, haematocrit; Tk, red blood cell rigidity), and sympathetic and parasympathetic indices of nocturnal autonomic activity (temporal and frequency analysis of heart rate variability) were thus compared between a group of nine SCT subjects and a group of nine control subjects. eta(b) was higher in the SCT group than in the control group while Hct, eta(p) and Tk were not different. Global variability (SDNN, SDNNIDX) and parasympathetic (PNN50, RMSSD, HF) indices were significantly lower in the SCT group compared with the control group, while the LF/HF ratio was highly increased, underlining a major sympathetic shift. The autonomic imbalance in SCT subjects was mainly related to lowered parasympathetic activity. Thus, our study suggests an additional global decrease and imbalance of autonomic nervous system activity to biological disorders of SCT carriers, that may constitute further risk factors for cardiac complications in this population.

Adult↗

Hyperoxia during recovery from consecutive anaerobic exercises in the sickle cell trait.

The sickle cell trait (HbAS) does not affect anaerobic exercise performance. However, lower blood lactate concentrations ([La-]) are consistently found during repeated anaerobic exercise in HbAS, and could be related to type of recovery. To study this, on three different occasions 17 HbAS and 17 matched control athletes (HbAA) underwent a series of three maximal cycle exercise tests of approximately 2-min duration, separated by 10-min recovery periods of rest, breathing either room air (P) or 100% oxygen (H), or of light pedaling (A). In all tests, work performed, heart rate, blood hematocrit, and [La-] were measured. Despite similar evolution of performance in each series of three anaerobic exercises, significantly lower [La-] were consistently found in HbAS in P and A, compared to HbAA (P < 0.0001). However, in H, similar [La-] was found in HbAS and HbAA. Higher mean heart rates were consistently measured in HbAS at exhaustion, and during the first 4 min of recovery, these differences being unrelated to type of recovery. We conclude that type of recovery does not influence subsequent performance in HbAS or HbAA. We speculate that improved regional oxygen availability in exercising muscle is associated with marked modification of lactate kinetics in highly trained HbAS, but not in similarly fit HbAA athletes.

Adult↗

Effect of different modalities of exercise and recovery on exercise performance in subjects with sickle cell trait.

The sickle cell trait (HbAS) does not seem to affect exercise performance. It remains unclear, however, whether the capability to sustain repeated brief maximal effort and recovery by HbAS subjects, is also preserved. To study this, nine HbAS and nine matched controls underwent on two different occasions, a series of four, approximately 2-min duration, maximal cycle exercise tests separated by 20-min recovery periods of either absolute rest (P) or light pedaling (A) as well as an incremental test to exhaustion. In all tests, work performed, heart rate, blood hematocrit, lactate, and serum creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (GOT) were measured. Performances were similar in HbAS and HbAA subjects in both the predominantly anaerobic and aerobic exercise series. There were no observable differences in work, power, or heart rate in the two groups both during peak exercise or recovery periods. A significant hemoconcentration was observed during P, with hematocrit increasing in HbAS from 46.4 +/- 0.7% to 48.3 +/- 0.4% at the end of the last recovery period. Similar changes were seen in HbAA. Significantly greater fluid losses were found during A (1.3 +/- 0.2 l in A and 0.6 +/- 0.1 l in P for HbAS; P < 0.001), but fluid losses were similar in each type of recovery in the two groups. Despite similar performance, significantly lower blood lactate concentrations were consistently found in HbAS in each of the three exercise series (P < 0.001). Lower lactate levels in HbAS were observed only at exercise loads above the lactate threshold during the incremental test (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Hemoglobin synthesis studies of a family with alpha-thalassemia trait and sickle cell trait.

The ratio of total globin alpha to beta chain synthesis was determined in reticulocytes isolated from the blood of the members of a black family, some of whom had sickle cell trait with low blood HbS concentrations (25-30%). The results support the hypothesis that sickle cell trait individuals with low HbS concentrations also carry a gene for alpha-thalassemia.

Anemia, Sickle Cell↗

Clinical profile of sickle cell trait.

OBJECTIVES: Although sickle cell trait is considered a harmless condition in ordinary circumstances, a large number of pathological conditions have been attributed to it often without a scientific basis. Many patients visit this centre with various complaints and on testing are found to be sickle cell trait. Hence it was thought necessary to analyse these cases to find out the nature of their ailments. METHODS: Two hundred cases of sickle cell trait diagnosed by sickling test and hemoglobin electrophoresis on CAM, and 150 age and sex matched control cases with normal hemoglobin phenotype from a survey were studied. Hemoglobin estimation was done in all by cyanmethemoglobin method. Besides history and clinical examination other relevant investigations were done as necessary to arrive at the diagnosis. Seven cases of sickle cell trait were asymptomatic while the rest were suffering from different conditions. 51% of sickle cell trait and 86% of control cases had mild to severe anaemia which improved with iron therapy in trait cases. Hepatomegaly (11% vs 4.6%), epistaxis (5% vs 0.66%) and cholelithiasis (3% vs 0%) was seen in significantly more number in sickle cell traits than the control cases. Splenomegaly and midsystolic murmurs were present in higher percent of cases but was not statistically significant. There was one case of epilepsy with multiple small infarcts in the brain and another with focal fits with epileptogenic focus in the left cerebral hemisphere where no other cause could be found except sickle cell trait. CONCLUSION: The ailments of sickle cell trait cases are like persons with normal hemoglobin. Anaemia is not more frequent and can improve with iron therapy. However, hepatomegaly, epistaxis, cholelythiasis are seen more frequently and minor cerebral infarcts probably can occur in sickle cell trait. These require more elaborate studies to decide their pathogensis.

Adolescent↗

Lung volumes and diffusion capacity in sickle cell trait.

Patients with sickle cell anemia have a restrictive ventilatory pattern, with reduction in diffusion capacity of the lung (DLco) and lung volumes. Diffusion capacity and lung volumes are reported as either normal or reduced in subjects with sickle cell trait. Thirteen subjects with sickle cell trait, age range 25 to 79 years, were compared with 13 normal subjects matched for age, sex, height, and smoking patterns. There was no significant difference in mean values of DLco or lung volume for the two groups. Neither was there a consistent difference for age-matched individuals. Normal lung function in sickle cell trait as opposed to sickle cell disease is probably related to the fact that the former have fewer, if any, pulmonary infectious and infarctive episodes.

Adult↗

Sickle cell trait and aviation.

Sickle cell trait is a benign genetic abnormality which has been wrongly projected as a health hazard in aviation. Conflicting reports on the relationship between this trait and flying exist in the literature. Limitations placed on sickle trait individuals unfairly stigmatize large numbers of people, both socially and economically. The imprecise identification of the sickle hemoglobinopathies and unrecognized interactions of other abnormal hemoglobins with hemoglobin S have perpetuated the controversy. There is a tendency to use isolated anecdotal incidents as evidence of increased morbidity in sickle cell trait; however, it has not been documented that hypoxic conditions cause in vivo sickling in pure trait carriers. An analysis of the definitions of the hemoglobinopathies, the molecular basis of hemoglobin S, the interactions of abnormal hemoglobins, and the sickling phenomenon shows both that there is no evidence that the sickle trait is a health hazard and that most of the literature contrary to this finding is invalid.

Aerospace Medicine↗

On the protective mechanism of the sickle cell trait (HbAS).

The sickle cell trait has been reported to offer some protection against anaemia in pregnancy. Some attribute this to the break up of the cells which release iron for the synthesis of haemoglobin. The hypothesis presented here is that the 'partial' protective mechanism of the sickle cell trait is due to increased erythropoietic activity.

Anemia↗

[Cardiac surgery using cardiopulmonary bypass in a patient with sickle-cell trait].

The sickle-cell gene is most concentrated in West Central Africa, the northeast corner of Saudi Arabia and East Central India. Sickle cell trait is the heterozygous condition for Hb S gene. Thirty to fifty per cent of their hemoglobin is Hb S and the remainder is Hb A. The sickle-cell crisis is induced by hypoxia, hypercarbia, acidosis, low flow condition, and hypothermia, which leads to vasoocclusion. A 39-year-old black man from Burkina Faso located in West Africa with left ventricular rupture was admitted for operation using cardiopulmonary bypass (CPB). He had been diagnosed as sickle-cell trait. The Hb S concentration was 36.2 per cent before operation with hemoglobin electrophoresis. During CPB, the minimum blood temperature was 31 degrees C and an aortic cross-clamp was not done. Total CPB time was 1 hour 31 minutes. Use of vasodilator and hyperventilation was effective. No neurological sequelae were observed.

Adult↗

Fetal outcome and childhood mortality in offspring of mothers with sickle cell trait and disease.

The sickle cell hemoglobinopathy is a major public health problem which causes high morbidity and mortality in India. Although the hematological and clinical profile of the patients is extensively studies. The reproductive outcome of mothers afflicted with sickle cell trait and disease is still unknown in India. In a retrospective study, we have examined the reproductive profile of 190 mothers afflicted with sickle cell, attending Medical Out-Patient Department at V.S.S. Medical College Hospital, Burla in Western Orissa, India during the year 1991-1992. Seventy-three mothers who were found normal after medical examination and were free from hemoglobinopathic disorders, anemia, jaundice, iron deficiency, etc. constituted the control group and 66 mothers with sickle cell trait and 51 with sickle cell disease formed the study group. The reproductive history was recorded for number of conceptions, fate of offspring, live birth, surviving children and childhood mortality. Hematological investigations and hemoglobin electrophoresis were done as per the standard procedure. There was no difference in mean number of livebirths per mother between controls and sickle cell trait mothers. But between the controls and sickle cell homozygotes (p < 0.01), and sickle cell trait and disease (p < 0.01) mothers, this mean number was significant. For abortions/miscarriages, the difference between controls and sickle cell homozygotes (p < 0.001), and sickle cell trait and disease (p < 0.01) mothers was highly significant. The number of stillbirths per mother in homozygous sickle cell mothers was higher (p < 0.01) as compared to controls. There were significantly higher childhood deaths in sickle cell trait (p < 0.05) and disease (p < 0.05) mothers than in the controls. It seems that the sickle cell heterozygote and hemoglobin E heterozygote mothers are genetically better fit than the sickle cell homozygotes. Further, the sickle cell disease is clinically severer than the hemoglobin E disease in India probably due to molecular diversity.

Adolescent↗