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PubMed1984

The sickle cell trait in relation to the training and assignment of duties in the armed forces: III. Hyposthenuria, hematuria, sudden death, rhabdomyolysis, and acute tubular necrosis.

Although the sickle cell trait (SCT) is usually a benign and innocuous carrier state or condition rather than a disease, those with the trait are capable of developing any and all types of vascular occlusive lesions that have been observed in patients with sickle cell anemia. Obstructive vascular lesions in individuals with SCT occur infrequently, but when they do occur they are disabling and may be life-threatening. Disabilities attributed to in vivo sickling have the potential of seriously impeding the success of military missions. When selecting recruits to be trained and assigned to special operations, consideration should be given to hyposthenuria, the possibility of hematuria and to exercise-induced syndromes. Exertion to the point of exhaustion in previously healthy individuals with SCT may cause sudden death, rhabdomyolysis, and acute tubular necrosis. In vivo sickling of erythrocytes is a superimposed and late contributory and complicating factor of exertional syndromes.

Acute Kidney Injury↗
PubMed2006

Effects of short supramaximal exercise on hemorheology in sickle cell trait carriers.

This study compared the hemorheological profile at rest and in response to a short supramaximal exercise test between sickle cell trait (SCT) carriers and a control group. Eight SCT carriers and eight control subjects performed a ramp exercise test on a cycle ergometer conducted to maximal oxygen uptake (VO2max). One week later, they performed a supramaximal exercise test consisting of pedaling for 1 min at 110% VO2max. Blood viscosity (eta(b)), plasma viscosity (eta(p)), hematocrit (Hct) and red blood cell (RBC) rigidity were assessed at rest, at the end of exercise and at the 15th, 30th and 60th min of recovery. Exercise increased eta(b), eta(p) and Hct above resting values in both groups and these parameters remained higher until the 15th or 30th min of recovery as compared to resting values. RBC rigidity was unchanged from baseline values in both groups during exercise and recovery. No difference was observed between the two groups for eta(p) and Hct but eta(b) and RBC rigidity were higher in the SCT carriers at every time point compared with the control group. The higher RBC rigidity and eta(b) found in SCT carriers at rest and in response to a brief supramaximal exercise might constitute a risk factor for microcirculatory complications. Indeed, a short supramaximal exercise test may not be completely inoffensive for SCT carriers.

Adult↗
PubMed1985

Haemorheological parameters in hypertensive Nigerians with and without sickle-cell trait.

Haemorheological parameters including whole blood (WBF) and erythrocyte filterability (EF), haematocrit (H'ct), haemoglobin levels (Hb) and plasma fibrinogen concentration (PFC) were measured in 61 adult Nigerians with uncomplicated essential hypertension during the course of their routine anti-hypertensive treatment. Results from these patients were compared to those of 39 age and sex-matched normotensive controls. Sixteen (26.2%) of the hypertensive patients and 6 (15.4%) of the controls had the sickle-cell trait (HbAS); the rest were normal homozygotes (HbAA). Although there were no significant difference between WBF in the HbAA-hypertensive and control groups, the former had a significantly lower EF than the latter (p less than 0.025). Both WBF and EF were highly significantly decreased in the HbAS-hypertensives (p less than 0.001). Significant differences in H'ct and Hb levels between HbAA-hypertensives and controls were attributed to sex rather than to hypertension per se. Plasma fibrinogen concentration values were consistently and significantly elevated in all hypertensives irrespective of sex or haemoglobin genotype. In contrast to the HbAA-hypertensives, all 16 HbAS-hypertensives had a persistently raised diastolic blood pressure above 90 mm Hg, suggesting that these patients are either resistant or are less responsive to conventional anti-hypertensive therapy. A more extensive follow-up study is in progress to assess the possible relationship of these parameters and blood pressure, particularly in hypertensive individuals with sickle-cell trait (HbAS).

Adult↗
PubMed2005

Hemorheology, sickle cell trait, and alpha-thalassemia in athletes: effects of exercise.

PURPOSE: This study investigated hemorheological parameters in response to exercise in sickle cell trait (SCT) athletes with or without alpha-thalassemia METHODS: Six athletes with SCT (HbAS), 7 athletes with SCT and alpha-thalassemia (HbASAT), and 10 control athletes (HbAA) performed a progressive and maximal exercise test on cycloergometer. Blood viscosity (etab), plasma viscosity (etap), etab at corrected hematocrit (etab45), hematocrit (Hct), and red blood cell (RBC) rigidity were assessed at rest, at maximal exercise and 24 h after exercise RESULTS: etab and etap were not different between the three groups at any time. Exercise induced changes in etab in HbAA and HbASAT groups but not in HbAS group. etab45 was higher in HbAS group compared with the other groups (P < 0.05), at rest and 24 h after exercise and increased only in HbAA group in response to exercise. HbAS group had lower Hct than HbAA group at any time. Hct and etap increased after exercise and declined under baseline values 24 h after exercise in all groups. RBC rigidity was higher in HbAS group compared with HbAA and HbASAT groups at any time, and was lower and higher at maximal exercise and 24 h after exercise, respectively, in all groups compared with resting values CONCLUSIONS: These results demonstrate that HbAS group is prone to higher RBC rigidity, which might lead to hemorheological alterations that are thought to participate to microcirculation disorders. However, these alterations are limited by the coexistence of alpha-thalassemia. Moreover, hemorheological parameters were not further impaired in SCT athletes with or without alpha-thalassemia in response to exercise. Training status might be protective from physiological stresses usually leading to sickling process in SCT carriers.

Adult↗
PubMedDate not supplied

Pathophysiology of a sickle cell trait mouse model: human alpha(beta)(S) transgenes with one mouse beta-globin allele.

As a potential model for sickle cell trait (AS), we examined mice containing one normal mouse beta-globin allele in combination with a human hemoglobin S (h(alpha)beta(S)) transgene (m(beta)/hS). The mice segregated into two subpopulations containing low and high proportions of hemoglobin S (m(beta)/hS1 and m(beta)/hS2, respectively) that was associated with one or two human h(alpha)beta(S) transgenes. We noted striking kidney pathology (cortical cysts, hyperplastic tubules, and glomerulonephritis), increasing with age and with greater severity in m(beta)/hS1. mBeta/hS2 animals were largely tolerant to 5% O(2) for 1 h, whereas 80% of m(beta)/hS1 mice died, exhibiting acute sequestration of erythrocytes in spleen, liver, and heart. These pathologies appear to result from a decreased oxygen affinity of the hybrid (human alpha/mouse beta) hemoglobins with a mild beta-thalassemia phenotype. Thus, these mouse models of sickle trait seem to manifest their renal pathology and sensitivity to hypoxia by mechanisms related to low tissue oxygen delivery and are different from the human syndrome. Analyses of parameters such as P(50), red cell indices, and genetic background are necessary in establishing potential relevance of any mouse model of the sickle cell syndromes.

Alleles↗
PubMed2006

Prevalence of -alpha(3.7) and alpha alpha alpha(anti3.7) alleles in sickle cell trait and beta-thalassemia patients in Mexico.

The aim of this study was to determine the frequency of alpha-globin gene mutations in three groups of Mexican unrelated individuals. The first two groups were normal and sickle cell trait individuals from the Costa Chica region, a place with a 12.8% frequency of HbS carriers, and the third group comprised of Mexican mestizo patients with beta-thalassemia. We searched for -alpha(3.7) and -alpha(4.2) alpha(+)-thalassemia deletion alleles, as well as the alpha alpha alpha(anti3.7) triplication through long-gap PCR. The alleles -alpha(3.7) and alpha alpha alpha(anti3.7) were found in the heterozygote state only; 19% of the normal subjects had the -alpha(3.7) allele, and 2% showed the alpha alpha alpha(anti3.7) allele. In individuals with the sickle cell trait, 17% had the -alpha(3.7) deletion, and the alpha alpha alpha(anti3.7) triplication was observed in 3% of these individuals. We revealed that 16% of the subjects with beta-thalassemia showed the -alpha(3.7) deletion and 28% the alpha alpha alpha(anti3.7) triplication. The -alpha(4.2) deletion was not detected in any individual. The frequency of the -alpha(3.7) allele was roughly the same in the three groups studied; this can be explained by the fact that the three groups have common genes from Africa and the Mediterranean, where a high prevalence of alpha(+)-thalassemia has been observed. To our knowledge, the frequency of alpha alpha alpha(anti3.7) triplication observed in the Mexican beta-thalassemia patients is the highest reported. As the -alpha(3.7) and alpha alpha alpha(anti3.7) alleles are very common in our selected populations, we believe that there is a need to investigate systematically the alpha-globin gene mutations in all hemoglobinopathies in the Mexican population.

Alleles↗
PubMed1984

Recurrent hematuria in 4 white patients with sickle cell trait.

Extensive investigations failed to disclose the etiology of recurrent gross hematuria in 4 white patients of Algerian descent. Hemoglobin electrophoresis revealed sickle cell trait in all cases. The hematuria ceased after bed rest and hydration in 3 patients, and following partial nephrectomy after visualization of the bleeding site at operative nephroscopy in 1. We recommend that hemoglobin electrophoresis be considered when evaluating every patient, black or white, presenting with unexplained hematuria.

Adult↗
PubMed1995

Acute exertional rhabdomyolysis and its relationship to sickle cell trait.

Exertional rhabdomyolysis, a syndrome characterized by skeletal muscle degeneration and muscle enzyme leakage, has been shown to occur in normal, healthy individuals following strenuous exercise. In severe cases, this syndrome can result in renal failure and sudden death. Although anyone who performs strenuous exercise may be at risk for developing exertional rhabdomyolysis, some individuals may be more susceptible than others. A number of case reports of exertional rhabdomyolysis involve persons with sickle-cell trait, leading to the theory that these individuals might be at greater risk for developing the syndrome than those without this trait. This article discusses the etiology of exertional rhabdomyolysis, the associated risk factors for persons with sickle-cell trait, and the recommended preventive measures. Additionally, several case studies of exertional rhabdomyolysis are reviewed.

Journal Article↗
PubMedDate not supplied

Sickle cell trait, malaria and anaemia in Zambian pregnant women.

IN a sample of 424 Zambian pregnant women a series of tests were made: sickle cell test, haemoglobin and packed cell volume estimations and screening of a thick blood smear for malaria and a thin blood smear for the presence of signs of anaemia. More anaemia was found in the primigravidae than in the multigravidae. The Hb-level was found to be lower with primigravidity and independently of this gravidity effect, also with malaria. Taking into account the higher malaria frequency in primigravidae, this group must be considered as a high risk group for the development of anaemia. The presence of the sickle cell trait was shown to have no effect on anaemia and malaria. In addition to the tests during pregnancy, the placentae and umbilical cords of 155 women were screened for malaria, as were the mothers just before delivery. More malaria parasites were detected in the placenta of the primiparous as compared with the multiparous women. Peripheral parasitaemia was strikingly less prevalent than infestation of the placenta.

Adolescent↗
PubMed1981

The proportion of Hb A2 is higher in sickle cell trait than in normal homozygotes.

The proportion of Hb A2 was 3.53 +/- 0.94 per cent in the blood of 69 persons with sickle cell trait (A/S) and 2.88 +/- 0.69 per cent in a like number with a normal (A/A) genotype using a radial immunodiffusion assay. This differs significantly at the 0.1% level by the paired comparison technique. It is proposed that this effect is due to the impaired association of beta S with alphaA chains allowing more of the latter to combine with delta-chains. A similar phenomenon may account for the increased proportion of Hb A2 observed in beta-thalassemia. The proportion of Hb F did not differ in the two genotypes.

Anemia, Sickle Cell↗
PubMed2005

Sickle cell trait and the risk of Plasmodium falciparum malaria and other childhood diseases.

BACKGROUND: The gene for sickle hemoglobin (HbS) is a prime example of natural selection. It is generally believed that its current prevalence in many tropical populations reflects selection for the carrier form (sickle cell trait [HbAS]) through a survival advantage against death from malaria. Nevertheless, >50 years after this hypothesis was first proposed, the epidemiological description of the relationships between HbAS, malaria, and other common causes of child mortality remains incomplete. METHODS: We studied the incidence of falciparum malaria and other childhood diseases in 2 cohorts of children living on the coast of Kenya. RESULTS: The protective effect of HbAS was remarkably specific for falciparum malaria, having no significant impact on any other disease. HbAS had no effect on the prevalence of symptomless parasitemia but was 50% protective against mild clinical malaria, 75% protective against admission to the hospital for malaria, and almost 90% protective against severe or complicated malaria. The effect of HbAS on episodes of clinical malaria was mirrored in its effect on parasite densities during such episodes. CONCLUSIONS: The present data are useful in that they confirm the mechanisms by which HbAS confers protection against malaria and shed light on the relationships between HbAS, malaria, and other childhood diseases.

Child, Preschool↗
PubMed1981

Effect of a 'sickling pulse' on calcium and potassium transport in sickle cell trait red cells.

1. To trace the early development of the extensive functional membrane abnormalities found in sickle cell anaemia red cells which result from polymerization of haemoglobin S, we followed the effects on Ca and K transport of an in vitro sickling pulse in sickle cell trait (SA) red cells, whose membranes are initially normal.2. Sickling induced a progressively larger uptake of Ca in fed, starved and ATP-depleted SA cells, always substantially higher than that in normal (AA) red cells under comparable conditions. The fraction of ionized Ca within the SA cells, estimated from the equilibrium distribution of (45)Ca induced by the ionophore A23187 was about 0.4 of the total Ca content and similar in SA and AA cells.3. With ATP-depleted SA cells, Ca uptake (representing Ca permeability) was maximal during sickling and was only partially reduced towards normal after desickling. Net Ca uptake during sickling of fed or starved SA cells reverted to net Ca loss upon reoxygenation, irrespective of the Ca gradient, indicating full restoration of the low Ca permeability of the control conditions.4. Following desickling of both fed and starved SA cells, the rates of uphill extrusion of Ca gained during sickling were much smaller than those expected with normal Ca pumps operating at similar internal Ca concentrations.5. After 2 hr sickling ATP levels in starved SA cells were reduced by 50% regardless of the presence or absence of Ca in the medium; therefore sickling-induced Ca uptake was associated with no measurable consumption of ATP due to Ca-pump activity.6. With ATP-depleted SA cells, a Ca uptake of 2-3 mumole/l. cells elicited a maximal response of the K permeability system resulting in full equilibration of the K pools in the cell suspensions. Sickling of fed and starved SA cells produced a small increase in K permeability which was entirely independent of the presence or absence of Ca.7. Sickled forms persisted after reoxygenation only with ATP-depleted SA cells and were more frequent after sickling in the presence of Ca (about 20%) than in a Ca-free medium (about 4%).8. These findings show that initial sickling produces an increased Ca permeability whose extent and reversibility depends on the metabolic state of the cells, and a partial Ca-pump failure, which appears to be irreversible. We confirm a small sickling-related, reversible increase in K permeability but a Ca-dependent increase in K permeability does not occur unless the cells are fully depleted of ATP. The implications for sequential development of related abnormalities in SS cells are discussed.

Adenosine Triphosphate↗