PubMed Health⌕ Search

Biomedical subjects

R J Hayes

Publications and source records attributed to R J Hayes.

At least 109 records · Page 6Linked to original sources
PubMed1986

Social and environmental factors associated with the risk of child mortality in a peri-urban community in The Gambia.

A group of 479 children born in a peri-urban West African community during a two-year period was studied in an attempt to identify social and environmental factors associated with the risk of dying in early childhood. Comparison of the characteristics of the 17 children that had died with those of the 462 survivors suggested an increased risk among the children of self-employed women, and among children living in compounds in which animals were kept. Of 500 mothers who were studied (including some whose children were born elsewhere), 145 had experienced at least one child death. When these 145 women were compared with the remaining 355, several factors related to living conditions, maternal education and health knowledge were found to be associated with the risk of child mortality.

Adult↗
PubMed1986

The impact of physico-chemical stress on the toxigenicity of Vibrio cholerae.

The expression of toxigenicity by Vibrio cholerae, before and after exposure to various conditions of salinity, pH and cation composition and concentration, has been measured. Exposure to these conditions did not select for hyper- or hypo-toxigenic strains. This suggests that toxigenic V. cholerae O1 are unlikely to lose their toxigenicity when exposed to environmental stress and that V. cholerae toxin production is not a response to the stresses included in this study. These results are consistent with an aquatic reservoir for toxigenic V. cholerae O1.

Cholera Toxin↗
PubMed1986

Seasonal variations in the nutritional status of urban Gambian children.

1. Children aged 6-35 months in an urban community in The Gambia, West Africa, were weighed and their lengths measured at four surveys over an 18-month period, twice towards the end of the rains, and twice during the dry season. 2. Relative to international standards, height-for-age deteriorated steadily with age, while weight-for-age fell sharply in the second-half of infancy but showed no further deterioration from 12 to 35 months of age. 3. Height-for-age showed little seasonal variation, but weight-for-age and weight-for-height were lower at the end of the rains than during the dry season. Weight and height velocities were much lower during the rains than in the dry season, with more than 20% of the children losing weight during the rains. Possible reasons for these seasonal variations are discussed. Compensatory weight gain in the dry season exceeded the velocity expected from the standards in children aged 12 months or more, but height velocity fell below the standards all year. 4. The results are compared with previous findings from Keneba, a rural Gambian village. Weight velocity during the dry season was similar in the two communities, but the village children experienced a sharper decline in weight gain during the rains. 5. These results suggest that seasonal ecological factors may seriously influence the nutritional status of children living in an urban environment with adequate availability of food.

Body Height↗
PubMed1986

Haemoglobin gene frequencies in the Jamaican population: a study in 100,000 newborns.

The gene frequencies of abnormal haemoglobins have been determined in a group of 100,000 Jamaican newborns screened over a period of 8 1/2 years. The population is predominantly of West African origin and the survey represents approximately one quarter of all island deliveries within the period of the study. The common beta globin chain abnormalities beta s and beta c occurred with gene frequencies of 0.055 and 0.019 respectively; beta thalassaemia was relatively rare. In contrast, alpha thalassaemia was quite common, occurring with a gene frequency of 0.183. In addition to these common abnormalities, the frequencies of 256 rare abnormal haemoglobins are described. This survey thus represents a complete and accurate documentation of the alpha and beta globin variants that occur in the Jamaican population.

Gene Frequency↗
PubMed1986

Prepubertal growth and skeletal maturation in children with sickle cell disease.

In a longitudinal study of 298 children with homozygous sickle cell (SS) disease and 157 children with hemoglobin SC disease, between birth and 9 years of age, observations of weight and height were made. These were compared with similar data derived from an age- and sex-matched group of 231 children with a normal hemoglobin (AA) genotype. Growth in children with SC disease was not significantly different from that in normal children, but children with SS disease had statistically significant, and progressive, deficits in both weight and height before 2 years of age. The average deficit approached 1 SD below the normal mean for age by 9 years. Observations of skeletal maturity, based on radiologic assessment of bone age at the wrist, were made on a proportion of these children at 5 and 8 years of age. Children with SS disease were significantly retarded at 8 years but not 5 years, which is consistent with increasing deficit in height. These observations confirm the early impact of SS disease on physical development and provide standards from which clinical expectations of growth may be derived. The relevance of these findings and their relationship to the characteristic delay in pubertal development is discussed together with a review of possible etiologic factors. The benign nature of SC disease is endorsed by the absence of an effect on growth in the prepubertal child.

Age Determination by Skeleton↗
PubMed1986

Admissions to a rural hospital in the West Nile District of Uganda over a 27 year period.

An analysis is presented of data on all 30 129 inpatient admissions to a mission hospital in the West Nile District of Uganda in the 27 year period from July 1951 to August 1978. For most of this period the hospital was staffed by the same two doctors. For each patient admitted, a record was made of their age (adult or child), sex, place of residence, duration of stay in hospital, diagnosis and vital status at discharge. The annual number of admissions increased steadily from around 300 in 1952 to over 1600 in 1966 and subsequently declined to about 900 in 1977. Sixty-five per cent of admissions were medical, 12% surgical, 11% obstetric and 9% gynaecological. Thirty per cent of admissions were children (aged 0-9 years). Forty-five per cent of admissions were from those resident in the same county as the hospital and another 20% were from an immediately adjacent county. Infective and parasitic conditions (including respiratory diseases) accounted for over 60% of admissions among children and over 38% of admissions among adults (excluding obstetric patients). The six most common causes of admission were: uncomplicated delivery (2308 admissions), pneumonia (2020), hookworm (1999), malaria (1806), schistosomiasis (1742) and diarrhoea (1041). In total 1960 deaths were recorded (6.5% of all admissions). High case fatality rates were observed for tetanus (61%), immaturity (54%), meningitis (38%), kwashiorkor (21%), other malnutrition (19%) and anaemia (19%). A striking increase in the number of admissions for measles was observed in the period 1976 to 1978. Admission rates for schistosomiasis (S. mansoni) appeared to be highest from counties adjacent to the Nile and 104 deaths were recorded among the 1742 patients with this as the primary diagnosis. Admissions for diabetes, as a percentage of all admissions increased from 0.2% in 1951-54 to 1.5% at the end of the study period. Marked seasonal variations in admission patterns were found for diarrhoea, measles, meningitis and respiratory infections, the last two, but not diarrhoea, being most common in the wettest months. Admissions for malaria showed no strong seasonal associations. Despite the limitations of hospital-based data, it is argued that the data analysed provide a reasonable indication of the important causes of severe morbidity and mortality in the district. Furthermore, some of the changes in admission patterns over time are likely to represent true changes in disease rates rather than artefacts of diagnosis or referral. The analyses presented indicate the value of simple record systems, carefully maintained.

Adolescent↗
PubMed1985

A serosurvey for leptospirosis in Trinidad among urban and rural dwellers and persons occupationally at risk.

A survey for leptospiral antibodies was made of 1,375 persons in northern Trinidad between mid-1977 and mid-1978. The subjects were employees in seven occupational categories thought to entail a high risk of exposure to leptospires, and members of the general population of three rural and two urban communities. They were questioned inter alia about their leisure and occupational activities, household water supply and effluent, and contact with animals. Leptospiral infection was found to be widespread in the general population but not primarily associated with employment. Among the occupational groups the highest prevalence of antibodies was found in sugar-cane workers (45% infected), while among the communities prevalence was highest in the rural village of Cacandee (37%) and lowest in Woodbrook (Port-of-Spain) (5%). Keeping cattle, hunting and walking barefoot in the countryside were significantly associated with leptospiral serology. Over-all, serogroups Icterohaemorrhagiae and Autumnalis each accounted for about 25% of the seropositives in the general population. Among the occupational groups Autumnalis was the most commonly found (36%). It accounted for 42% of the seropositive sugar-cane workers and 57% of the seropositive rice farmers.

Adult↗
PubMed1985

The haematology of steady state homozygous sickle cell disease: frequency distributions, variation with age and sex, longitudinal observations.

The steady state haematological characteristics observed in 1071 patients with homozygous sickle cell (SS) disease aged 5-66 years are presented. Cross sectional studies indicated that HbA2 levels were consistently higher in males but no age related change was apparent. Fetal haemoglobin levels were consistently higher in females and fell significantly in males between the 5-9 and 10-14 year age groups. Total haemoglobin was significantly higher in females before age 15 and higher in males after 20 years, a dramatic age related rise occurring in males between the 10-14 and 25-29 year age groups, and a fall in patients aged 40 years and over. The mean cell volume was consistently greater in females after 15 years and a marked age related rise occurred in both sexes between the 5-9 and 25-29 year age groups. Counts of irreversibly sickled cells were consistently higher in males. Reticulocytes fell significantly with age, while platelets and total bilirubin fell significantly after the age of 15 years. Longitudinal studies confirmed the increase in total haemoglobin levels in males over the ages 10-14 years, and a significant fall in males after the age of 30 years. Such studies also confirmed the fall in HbF in males aged 5-14 years, the increase in MCV in both sexes aged 5-29 years, and the fall in platelet counts in both sexes over the age of 20 years. These observations provide 'normal' values for patients seen elsewhere and also contribute to an understanding of factors determining the haemoglobin indices in SS disease.

Adolescent↗
PubMed1985

Eosinophilia and resistance to Schistosoma haematobium in man.

We have measured the levels of infection with Schistosoma haematobium in children resident in an endemic area of The Gambia before and 3 months after successful chemotherapy and following reinfection. An exposure index was calculated from data collected on water contact, cercarial densities and infected snail densities at water contact sites. Peripheral blood eosinophil levels were recorded and the ability of serum (heat inactivated) from the children to allow killing of schistosomula of S. haematobium was examined. Of 50 children with a post-treatment egg count of less than 1 ovum/10 ml urine, 26 were classified as reinfected, acquiring greater than 1 ovum/10 ml urine over the transmission season. Twenty-four were classified as not reinfected, acquiring less than 1 ovum/10 ml of urine over the same period. These two groups did not differ with respect to their estimated age, weight or pretreatment egg counts. Children who were reinfected had significantly higher levels of exposure and significantly lower peripheral blood eosinophil counts than children who were not reinfected. At all levels of exposure children with high eosinophil counts were less likely to be reinfected than those with lower counts. But antibody-dependent, complement-independent killing of schistosomula of S. haematobium by eosinophils was barely detectable and did not differ between reinfected and non reinfected groups. These observations suggest that subjects with elevated counts are less susceptible to reinfection but the mechanisms involved are not apparent.

Adolescent↗
PubMed1984

Genetic heterogeneity of histamine H2-receptors in the mouse vas deferens.

The ability of histamine to inhibit the overall contractile ('twitch') response of the isolated vas deferens of the mouse to electrical field stimulation (64 V pulse, 1 ms pulse width, frequency 0.2 Hz) was studied in nine inbred mouse strains. The strains were also characterized in terms of the potency of the histamine H2-receptor antagonist cimetidine in its inhibition of histamine-mediated effects. An apparently bimodal inter-strain variation (8-10 fold) in both characteristics was encountered, with three strains (SWR, A2G and C57BL/10ScSn) relatively sensitive (S) to both agonist and antagonist actions, and six (C3H, A, C57/BL6, DBA/2, Balb/C and 129/Sv) relatively insensitive (IS). These strain differences were independent of extracellular calcium concentration in the range 1.25-5 mM, and also independent of the frequency of tissue stimulation over the range 0.2-6.4 Hz. Representative S (SWR and A2G) and IS (DBA/2 and C3H) mouse vasa were also characterized in terms of their sensitivity to the agonist actions of dimaprit and the antagonist actions of tiotidine. In the S strain tissues, dimaprit produced 50% inhibition of the twitch response at 4.6-1.8 microM (mean +/- s.d.) and was able to elicit complete inhibition of the twitch response at concentrations greater than 100 microM, whereas 48.7 +/- 11.9 microM dimaprit was required to produce 50% inhibition of the twitch response in tissues from IS mice. In addition, the agonist actions of dimaprit were incomplete in the latter tissues, the drug eliciting no more than 75% inhibition of the twitch response at concentrations in the range 300-1000 microM. Tiotidine produced competitive antagonism of the actions of both histamine and dimaprit, the strain differences being of the same magnitude as those observed for cimetidine. 4 Mating of a representative S (SWR) and IS (129/Sv) strain produced F, mice with intermediate histamine and cimetidine sensitivities relative to the parental strains. A backcross of male F1 to female IS mice produced progeny displaying a range of histamine and cimetidine sensitivities representative of those seen in tissues from F1 and IS parental animals, however, the data were not bimodal. Thus, the backcross data provided no evidence to support single gene inheritance of histamine sensitivity and might suggest that more than one gene is responsible for these differences between S and IS mice.

Animals↗
PubMed1984

Blood rheology and proliferative retinopathy in sickle cell-haemoglobin C disease.

Haematological and rheological (plasma and serum viscosity, whole blood viscosity, and erythrocyte filterability) factors were studied in 31 age-sex matched pairs of patients with sickle cell haemoglobin C disease with and without proliferative sickle retinopathy (PSR). Patients with PSR had significantly higher mean cell haemoglobin and lower Hb F levels on average than the matched controls, but the viscosity and erythrocyte filtration indices did not differ between the 2 groups. There was, therefore, no evidence of rheological differences between patients with and without PSR at the time of the study, although transient rheological abnormalities at the time of development of PSR could not be excluded. Prospective longitudinal studies of rheology before, during, and after the development of PSR would be necessary to detect such changes.

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↗
PubMed1983

Effect of alpha thalassaemia on the rheology of homozygous sickle cell disease.

A study of rheological determinants (plasma viscosity, whole-blood viscosity, and erythrocyte deformability) was made in 24 matched pairs of patients with homozygous sickle cell disease, with and without homozygous alpha-thalassaemia 2. Patients with coexisting alpha-thalassaemia showed a significant increase in erythrocyte deformability measured as filtration of washed erythrocytes through 5 micron diameter pores and also as viscosity of whole blood at high shear rate (230s-1) and standard haematocrit (0.45). This rheological advantage may explain the beneficial effect of alpha-thalassaemia 2 on haematological parameters and clinical events in homozygous sickle cell disease.

Adolescent↗
PubMed1983

Body shape in young children with homozygous sickle cell disease.

Body shape, defined by detailed anthropometric measurement, was compared in 64 children with homozygous sickle cell (SS) disease, and in 123 children with a normal hemoglobin (AA) genotype, aged 4 to 6 years. Children with homozygous sickle cell disease showed an average reduction in weight, height, sitting height, limb length, interacromial and intercristal diameters, and skinfold thickness. They showed increased anteroposterior chest diameters with an increased anteroposterior-lateral chest diameter ratio. This report establishes that the effect of homozygous sickle cell disease on growth patterns in childhood is apparent before the age of 6 years. The relationship to changes in body shape, seen during adolescence and in affected adults, and their possible determinants, are discussed.

Anemia, Sickle Cell↗
PubMed1982

The interaction of alpha-thalassemia and homozygous sickle-cell disease.

Patients with homozygous sickle-cell disease may be homozygous for alpha-thalassemia 2 (alpha-/alpha-), may be heterozygous for alpha-thalassemia 2 (alpha-/alpha alpha), or may have a normal alpha-globin-gene complement (alpha alpha/alpha alpha). We compared the clinical and hematologic features of 44 patients who had sickle-cell disease and homozygous alpha-thalassemia 2 with those of controls with the two hematologic conditions. The patients with homozygous alpha-thalassemia 2 had significantly higher red-cell counts and levels of hemoglobin and hemoglobin A2, as well as significantly lower hemoglobin F, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, reticulocyte counts, irreversibly-sickled cell counts, and serum total bilirubin levels, than those with a normal alpha-globin-gene complement. Heterozygotes (alpha-/alpha alpha) had intermediate values. In the group with homozygous alpha-thalassemia 2, fewer patients had episodes of acute chest syndrome and chronic leg ulceration and more patients had splenomegaly, as compared with patients in other two subgroups. These data confirm previous suggestions that alpha-thalassemia inhibits in vivo sickling in homozygous sickle-cell disease and may be an important genetic determinant of its hematologic severity.

Adolescent↗
PubMed1982

Pneumococcal and other infections in children with sickle-cell hemoglobin C (SC) disease.

The pattern of infection was compared in 139 children with sickle cell-hemoglobin C (SC) disease and in 250 control children with a normal hemoglobin (AA) genotype ascertained at birth and followed prospectively for periods of zero to six years. Both infection incidence rates and survival curve analysis indicated highly significant increases in serious infection among children with SC disease. Respiratory infection and gastroenteritis were the most common infections, but only respiratory infections were significantly more frequent in SC disease. Pneumococcal bacteremia was confined to the SC group. No hematologic differences were apparent between SC patients with and without a history of serious infection, but infection was significantly more common in patients manifesting early splenomegaly.

Bacterial Infections↗