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Biomedical subjects

B Serjeant

Publications and source records attributed to B Serjeant.

14 recordsLinked to original sources
PubMed2004

Newborn screening for sickle cell disease in Brazil: the Campinas experience.

Newborn screening for sickle cell disease commenced in 1992 in Sao Paulo State and by the end of 2000, the programme covered 78 institutions in 36 municipalities with the screening of 281,884 babies. Initially based on liquid cord blood samples, these are being replaced by dried filter paper capillary samples to ease handling and avoid diagnostic confusion from maternal contamination. The prevalence of sickle cell trait (2.0%) and HbC trait (0.6%) increased significantly between 1996 and 2000, apparently because of improved detection rather than the later introduction of institutions serving populations with higher trait frequencies. There were 29 babies with homozygous sickle cell SS disease and 26 with sickle cell-haemoglobin C (SC) disease, the latter significantly exceeding expectation and possibly attributable to a nonrandom selection of partners. Sickle cell-beta thalassaemia syndromes were proportionately more common than in Jamaica, and it is possible that this results from interaction with other Brazilian populations carrying higher beta thalassaemia gene frequencies. The frequency of abnormal haemoglobins in this population is lower than in Jamaica, but clinically significant sickle cell disease occurred once in every 5527 births, comparable with the frequencies of other significant inborn errors of metabolism.

Brazil↗
PubMed2001

Red cell antibodies in patients with homozygous sickle cell disease: a comparison of patients in Jamaica and the United Kingdom.

The transfusion history and frequency of red cell antibodies in patients with homozygous sickle cell (SS) disease have been compared in 190 subjects from the Jamaican cohort study and 37 patients attending a sickle cell clinic in Manchester, England. The proportion of patients transfused did not differ between the groups although the number of units transfused and the frequency of red cell antibodies were significantly greater in the Manchester group. Immune antibodies occurred in three Jamaicans (2.6% of those transfused) and 16 UK subjects (76% of those transfused). Multiple antibodies occurred in 10 (63%) UK subjects but in no Jamaicans. Indications for transfusion also differed between the groups, Jamaican patients typically receiving 1-2 units for acute anaemia or acute chest syndrome, whereas UK patients frequently had multiple transfusions in preoperative exchange or prophylaxis programmes. The greater red cell alloimmunization among UK patients probably reflects both the greater use of transfusion and the disparity between donor and recipient populations in the UK.

Adolescent↗
PubMed1996

Determinants of haemoglobin level in steady-state homozygous sickle cell disease.

High total haemoglobin levels in homozygous sickle cell (SS) disease are a risk factor for painful crises, avascular necrosis of the femoral head, proliferative sickle retinopathy, and the acute chest syndrome. Since lowering the haemoglobin level may ameliorate these features, understanding the determinants of total haemoglobin may be of practical importance. A range of possible determinants including red cell characteristics, reticulocytes, serum iron, transferrin saturation, serum ferritin, alpha thalassaemia status, red cell mass and plasma volume, oxygen affinity, red cell survival, transferrin receptor and erythropoietin levels have been measured in 62 patients selected to provide a range of total haemoglobin and fetal haemoglobin levels. There were weak negative associations of haemoglobin with mean cell volume and mean cell haemoglobin concentration, strong negative associations with proportional reticulocyte counts, oxygen affinity, plasma volume, serum transferrin receptors, and erythropoietin levels and strong positive associations with red cell mass. Weighted analysis suggested that the statistically independent determinants of haemoglobin level were alpha thalassaemia, sex, red cell mass/body weight, plasma volume/body weight, fetal haemoglobin, and red cell count. The apparent contributions of red cell survival, P50, reticulocyte count, serum transferrin receptor and erythropoietin levels were explained by the effects of these other variables. The independent determinants as a group explained 91% of the variation in haemoglobin level.

Adult↗
PubMed1995

Improved survival in homozygous sickle cell disease: lessons from a cohort study.

OBJECTIVE: To examine whether simple interventions in a sickle cell clinic improve survival in sickle cell disease. DESIGN: Survival curve analysis and hazard ratios in a cohort study followed from birth. SETTING: MRC Laboratories (Jamaica) at the University of the West Indies, and Victoria Jubilee Hospital, Kingston, Jamaica. SUBJECTS: 315 patients with homozygous sickle cell disease detected during the screening of 100,000 consecutive non-operative deliveries between June 1973 and December 1981 at the main government maternity hospital, Kingston, Jamaica. INTERVENTIONS: Prophylactic penicillin to prevent pneumococcal septicaemia, parental education in early diagnosis of acute splenic sequestration, close monitoring in sickle cell clinic. MAIN OUTCOME MEASURES: Survival. RESULTS: Survival appeared to improve, the log rank test for trend comparing the first, second, and last third of the study reaching borderline significance (P = 0.05). Combined deaths from acute splenic sequestration and pneumococcal septicaemia-meningitis declined significantly (test for trend, P = 0.02). CONCLUSION: Early diagnosis and simple prophylactic measures significantly reduce deaths associated with homozygous sickle cell disease.

Adolescent↗
PubMed1993

The clinical significance of serum transferrin receptor levels in sickle cell disease.

Serum transferrin receptor (TfR) levels were measured in 182 children with homozygous sickle cell (SS) disease, 47 with sickle cell-haemoglobin C (SC) disease and 41 normal (AA) controls on their eighth birthday. Highly significant elevations occurred in SS compared to SC disease and in SC disease compared to AA controls. Females had higher levels than males in controls but lower levels than males in SS and SC disease. In SS disease, serum TfR levels tended to rise with age from 2 to 8 years, the change within individuals correlating with a change in reticulocyte count (r = 0.38, P = 0.017) and fall in fetal haemoglobin levels (r = -0.51, P = 0.004). Serum TfR levels did not change with infection or painful crisis but were markedly elevated in hypersplenism and fell following splenectomy in these subjects. In the aplastic crisis, serum TfR levels tended to rise following clinical presentation and then fall, reflecting the reticulocyte counts. These observations are consistent with serum TfR levels being a useful indicator of the degree of erythropoietic expansion in sickle cell disease.

Age Factors↗
PubMed1991

The haematology of homozygous sickle cell disease after the age of 40 years.

Haematological indices have been studied in 181 patients with homozygous sickle cell (SS) disease aged 40-73 years. Cross-sectional analyses in 5-year age bands indicated age-related decreases in HbF (males only), total haemoglobin and platelet counts. Longitudinal studies within individuals confirmed the downward age-related trend in haemoglobin and platelets and also revealed a falling reticulocyte count, most significant when expressed as absolute values. Total nucleated cells also fell although the decline was significant only in females. These observations are consistent with a progressive bone marrow failure which is not explained by the commonly occurring renal impairment in older SS patients since the changes persisted in analyses confined to patients with normal creatinine levels. The mechanism of this bone marrow failure is currently unknown.

Adult↗
PubMed1991

The red cell distribution width in sickle cell disease--is it of clinical value?

The red cell distribution width (RDW) has been studied during the clinical steady state in 1121 patients with homozygous sickle cell (SS) disease, 344 with sickle cell-haemoglobin C (SC) disease, 68 with sickle cell-beta+ thalassaemia, 49 with sickle cell beta 0 thalassaemia and in 130 control subjects with a normal (AA) genotype. The mean RDW was moderately increased in S beta + thalassaemia and SC disease and markedly increased in S beta 0 thalassaemia and SS disease. In SS, SC and S beta 0 thalassaemia genotypes, lower RDW values occurred in females and with alpha thalassaemia. The RDW correlated negatively with total haemoglobin, mean cell haemoglobin concentration, mean cell volume, and fetal haemoglobin (HbF) and positively with reticulocyte count in SS disease. A low RDW was associated with higher weight and less frequent dactylitis, painful crisis, acute chest syndrome, acute splenic sequestration, and hospital admissions. A low RDW in SS disease is consistent with a high total haemoglobin, high HbF, low reticulocyte count, alpha thalassaemia, and a more mild clinical course.

Adolescent↗
PubMed1983

A trial of folate supplementation in children with homozygous sickle cell disease.

A double blind controlled trial of supplementation with folic acid has been performed in 117 children with homozygous sickle cell (SS) disease aged 6 months to 4 years over a 1 year period. No megaloblastic change was observed in either group. At the end of the study period the folate supplemented group showed no significant differences in haemoglobin, growth characteristics, or in the proportion of children affected by major or minor infections, acute splenic sequestration, dactylitis or episodes of bone or abdominal pain. However, the folate supplemented group showed a significantly lower mean cell volume and the placebo group contained a significant excess of children experiencing multiple episodes of dactylitis. The results are compatible with mild folate deficiency in some patients in the placebo group but the absence of striking effects on haematology or growth suggest that the policy of regular folate supplementation in children with SS disease should be critically reviewed.

Anemia, Sickle Cell↗
PubMed1980

Haematological indices in normal negro children: a Jamaican cohort from birth to five years.

Haematological indices, including total haemoglobin, mean cell haemoglobin concentration, red cell count, mean cell volume, mean cell haemoglobin, reticulocytes, and serum iron values, in a cohort of 243 randomly selected Negro children with normal haemoglobin genotype, followed from birth to 5 years, are reported. Total haemoglobin fell rapidly from high levels at birth to a plateau at 2-6 months; a secondary fall occurred after 6 months and a gradual increase after 18 months. The red cell count also fell rapidly, but increased after 2 months to a plateau and then slowly declined from age 1-5. Mean cell volume and mean cell haemoglobin fell continuously from birth to the lowest values at 15 months and then progressively increased to the age of 5 years. Serum iron levels were low at one year of age (mean 9.7 mumol/l) increasing slowly by age 4 and sharply by age 5. Mean cell haemoglobin concentration fell gradually to 1-1 1/2 years and then increased progressively to age 5. Values for Hb, MCHC, MCV, and MCH were consistently and often significantly lower in males before the age of 2 years, compatible with greater depletion of iron stores. Serum iron values were generally lower in males but there was no sex difference at one year when highly significant differences in Hb, MCHC, MCV, and MCH occurred. The cause of sex differences in early haematological development is currently unclear.

Anemia, Sickle Cell↗
PubMed1979

Determinants of haemoglobin level in sickle cell-haemoglobin C disease.

The determinants of steady state haemoglobin levels in sickle cell-haemoglobin C (SC) disease were investigated by measuring routine haematological and biochemical indices, red cell survival, oxygen affinity, pitted erythrocytes, and red cell and plasma volumes in 31 adult patients (15 male; 16 female). Red cell survival was shortened in all subjects, and was positively correlated with haemoglobin level. However, many haemoglobin values were within the normal range, especially in male subjects. Palpable splenomegaly, which occured in 53% of patients, did not appear to affect haemoglobin level, red cell survival, plasma volume, or red cell volume, but was associated with lower platelet counts and decreased pitted red cells. Sex related differences were found in total haemoglobin, packed cell volume, conductivity cell volume, red cell count, and in the blood volume measurements. Red cell, plasma and total blood volumes in patients varied with weight and cube of height in manner observed in normal subjects, although red cell volumes were lower and plasma volumes were greater than in normal subjects of given height and weight. Anaemia in SC disease is related to the haemolytic rate but the major determinant appears to be an inappropriate increase in plasma volume.

Adolescent↗