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Biomedical subjects

A F Fleming

Publications and source records attributed to A F Fleming.

At least 55 records · Page 3Linked to original sources
PubMed1989

Haematological status of blood-donors with sickle cell trait and alpha thalassaemia in northern Nigeria.

Northern Nigeria is an endemic area for sickle haemoglobin (HbS), and it is common practice in many hospitals to accept blood for transfusion from donors with sickle cell trait (HbAS). In 212 healthy HbAS blood donors, the proportion of HbS was found to range between 24-47%. The HbS levels less than 38% were presumably due to the interaction of sickle-cell gene with the alpha + thalassaemia gene. Low HbS levels and presumed alpha + thalassaemia were associated with significant microcytosis and relatively low Hb A2 and Hb F, but differences were minimal. Carriers of sickle cell trait, with or without alpha + thalassaemia, appear to be acceptable as blood donors. Beta thalassaemia was not detected amongst 710 blood-donors.

Adolescent↗
PubMed1988

Possible aetiological factors in leukaemias in Africa.

The hypothesis that the true incidence of c-ALL is relatively uniform throughout the world is not supported by experience in tropical Africa, where ALL is uncommon under five years of age. A high rate of spontaneous somatic mutation in pre-B cells may initiate the development of c-ALL, but its progress could be determined by (i) a leukaemogenic agent causing a second genetic event, (ii) the effects of intense antigenic barrage, either stimulating or suppressing pre-B-cell mitosis, or (iii) genetic determinants. Epidemiological patterns in populations of low, intermediate and high socio-economic status may be classified I-III with increasing incidence of diagnosed T-ALL in children over five years and c-ALL in younger children, and subclassified A and B with decreasing incidence of BL. There may be two forms of AML, one similar to that seen in industrialized countries, the other occurring at high prevalence in African children of low socio-economic status, often presenting with chloroma, and perhaps associated with immune suppression secondary to malnutrition, malaria and other intercurrent infections. Uncontrolled exposure to petroleum and other chemicals, and the use of alkylating agents in treatment of neoplasms in young patients could emerge as important causes of ANLL in Africa. There are two varieties of CLL also, one similar to that seen in the western world, the other prevalent in adults below 45 years of age, especially women: transmission of a leukaemogenic agent is postulated, to which women are more susceptible due to immunosuppression during normal pregnancy. The human population and some subhuman primates of subSaharan Africa are the largest reservoir of HTLV-1, which shows association with B-CLL over 50 years of age and ATL.

Africa↗
PubMed1988

Seroepidemiology of human immunodeficiency viruses in Africa.

The first generation of serological tests for anti-HIV-1 gave so many false positives with African sera that it was wrongly postulated that the virus was endemic in Africa. As there is no simian or other virus sufficiently closely related to HIV-1 as to suggest a recent common ancestor, the evolution of HIV-1 is obscure and there is no current evidence to support the hypothesis of an African origin. However, the similarity of HIV-2 to SIV and its geographical distribution do suggest an evolution of this virus in west Africa. The earliest anti-HIV-1 positive serum was from a subject in Kinshasa in 1959. Seroprevalence rose in pregnant women in Kinshasa from 0.25% in 1970, to 3.0% in 1980 and 5.7% in 1986. When two sexually promiscuous groups are compared, seropositivity rose sharply in female prostitutes in Nairobi from 4% in 1981, to 59% in 1984 and 64% in 1986, a curve which is approximately parallel to, but three years later than that of homosexual males in San Francisco. In central and east Africa, HIV-1 is now epidemic from Congo to Kenya and from Uganda to Zimbabwe. In west Africa, both HIV-2 and HIV-1 are epidemic: seroprevalence of HIV-2 is highest in southern Senegal, Guinea-Bissau and Côte d'Ivoire: HIV-1 has the highest frequency in Côte d'Ivoire and Ghana. HIV-2 has not been reported, and HIV-1 is pre-epidemic in Africa north of the Sahara, Nigeria, Angola, Mozambique and southern Africa, being found at significant frequency only in female prostitutes, patients with STD, or, in Morocco and South Africa only, in male homosexuals. Seroprevalence is greatest in female prostitutes and patients with STD: infection is more frequent in urban than in rural populations, except in Uganda. The peak frequency is at 30-34 yr in males and 20-24 yr in females. Other groups at risk are infants born to infected mothers, and those requiring blood transfusions, especially pre-school children, patients with sickle-cell disease and pregnant women. The doubling time for seropositivity is about one year in the sexually active age range in some populations. Even at existing seroprevalence, decimation or worse of the most productive age groups is inevitable during the next few years in certain countries.(ABSTRACT TRUNCATED AT 400 WORDS)

AIDS Serodiagnosis↗
PubMed1986

Antibodies to HTLV-I in Nigerian blood-donors, their relatives and patients with leukaemias, lymphomas and other diseases.

Antibodies to HTLV-I have been detected in sera from 15 (2.0%) of 736 adult blood-donors in Nigeria, in 4 (20.0%) of 20 patients with chronic lymphatic leukaemia, 3 (10.0%) of 30 with non-Hodgkin's lymphoma, one of 12 with Burkitt's lymphoma and one of 7 with acute lymphoblastic leukaemia. The frequency of positivity was higher (3.6%) in the blood-donors from the guinea and wooded savanna of northern Nigeria than in those from the rain-forest and mangrove swamps of southern Nigeria (1.8% in Lagos and 0.7% in Calabar). Two of the 3 seropositive patients with lymphoma had clinical presentation and courses similar to those of Japanese and Caribbean patients with adult T-cell leukaemia/lymphoma.

Antibodies, Viral↗
PubMed1986

Seroepidemiology of human immunodeficiency virus in Africa.

Serum samples from 6015 African subjects without symptoms of the acquired immune deficiency syndrome (AIDS) or contact with the disease were examined for antibodies to the human immunodeficiency virus by a combination of an enzyme linked immunosorbent assay and radioimmunoprecipitation (2567 samples) or by immunofluorescence (3448 samples). Serum samples had been collected between 1976 and 1984 in Senegal (n = 789), Liberia (935), Ivory Coast (1195), Burkina Faso (299), Nigeria (536), Gabon (1649), Zaire (15), Uganda (164), and Kenya (433). Only four samples contained antibodies. Three of these were from attenders at the Lambarene clinic in Gabon and one from a villager in Senegal. By contrast, two out of six AIDS suspects from Guinea-Bissau, all 13 patients with AIDS from Kinshasa (Zaire), and two out of three of their contacts were seropositive, all these specimens having been collected in 1985. These data show that fewer than one in a 1000 subjects were seropositive for AIDS at the time of sampling before 1985 and do not support the hypothesis of the disease originating in Africa.

Africa↗
PubMed1986

A bibliography of the leukaemias in Africa, 1904-1985.

A bibliography of leukaemias in Africa is presented from 1904 to 1985. The literature is listed chronologically and is classified geographically (north, south, east and west Africa) and by leukaemia type. The epidemiology of leukaemias in Africa is discussed briefly, especially as to the rarity of acute lymphoblastic leukaemia under the age of four years, the frequency of chloroma, the young age of presentation of chronic granulocytic leukaemia, the frequency of chronic lymphatic leukaemia in adults, especially women, under 45 years in tropical Africa, and the frequency of infection by the human T-cell leukaemia-lymphoma (or lymphotropic) virus type I and of adult T-cell leukaemia-lymphoma.

Adolescent↗
PubMed1986

The prevention of anaemia in pregnancy in primigravidae in the guinea savanna of Nigeria.

Two hundred Hausa primigravidae at Zaria were divided into five groups in a randomized double-blind trial of antenatal oral antimalarial prophylaxis, and haematinic supplements. Group 1 received no active treatment. Groups 2 to 5 were given chloroquine 600 mg base once, followed by proguanil 100 mg per day. In addition, group 3 received iron 60 mg daily, group 4 folic acid 1 mg daily, and group 5 iron plus folic acid. Forty-five percent were anaemic (haemoglobin (Hb) less than 11.0 g dl-1) at first attendance before 24 weeks of gestation, and malaria parasitaemia (predominantly Plasmodium falciparum) was seen in 27%, of whom 60% were anaemic. The mean Hb fell during pregnancy in group 1, and seven patients in this group had to be removed from the trial and treated for severe anaemia (packed cell volume (PCV) less than 0.26). Only five patients in the other groups developed severe anaemia (P = 0.006), two of whom had malaria following failure to take treatment. Patients in group 1 had the lowest mean Hb at 28 and 36 weeks of gestation, and patients receiving antimalarials and iron (groups 3 and 5) had the highest Hb at 28 weeks, but differences were not significant, possibly due to removal from the trial of patients with severe anaemia. Anaemia (Hb less than 12.0 g dl-1) at six weeks after delivery was observed in 61% of those not receiving active treatment (group 1), in 39% of those protected against malaria but not receiving iron supplements (groups 2 and 4) and in only 18% of patients receiving both antimalarials and iron (groups 3 and 5). Folic acid had no significant effect on mean Hb. Proguanil was confirmed to be a highly effective causal prophylaxis. Prevention of malaria, without folic acid supplements, reduced the frequency of megaloblastic erythropoiesis from 56% to 25%. Folic acid supplements abolished megaloblastosis, except in three patients who were apparently not taking the treatment prescribed. Red cell folate (RCF) concentrations were higher in subjects with malaria, probably due to intracellular synthesis by plasmodia. Infants of mothers not receiving antimalarials appeared to have an erythroid hyperplasia. Maternal folate supplements raised infants' serum folate and RCF. Fourteen per cent had low birth weight (less than 2500 g), and the perinatal death rate was 11%; the greatest number were in group 1, but not significantly. A regime is proposed for the prevention of malaria, iron deficiency, folate deficiency and anaemia in pregnancy in the guinea savanna of Nigeria.

Adolescent↗
PubMed1985

A comparison of chloroquine and pyrimethamine as malaria chemoprophylactics in young Nigerian children.

The efficacy of chloroquine and pyrimethamine as malaria chemoprophylactics was investigated in young Nigerian children. Chloroquine resistance had not been documented in the study area; pyrimethamine resistance was probably present but uncommon. Children who received weekly chemoprophylaxis with pyrimethamine had a lower prevalence of malaria parasitaemia and malaria antibodies than children who received weekly chemoprophylaxis with chloroquine. Pyrimethamine given monthly gave a comparable degree of protection to chloroquine given weekly. Chloroquine frequently induced vomiting in young children and this may have impaired its efficacy as a prophylactic. We conclude that, in an area where neither chloroquine nor pyrimethamine resistance is prevalent, pyrimethamine is a better chemoprophylactic for young children than chloroquine.

Antibodies↗
PubMed1985

Malaria and haemoglobin genotype in young northern Nigerian children.

Plasmodium falciparum and P. malariae were found less frequently in blood obtained from Nigerian children under the age of two years who had the haemoglobin genotype AS than in blood films obtained from those who had the genotype AA. However, differences between the two groups were statistically significant only for P. falciparum asexual forms. The prevalence of malaria antibodies, as measured by an ELISA, did not differ significantly between the two groups.

Enzyme-Linked Immunosorbent Assay↗
PubMed1985

The ABO and Rhesus groups in the north of Nigeria.

ABO and Rhesus blood group data were analysed from 43187 blood donors belonging to 34 ethnic groups, predominantly from northern Nigeria. This is the largest series to be reported on from the whole of West Africa. Group O was found in 46.6% of all those examined, but the numbers varied from 33.13% to 64.35% in different ethnic groups. Group A was found in 23.05% and Group B in 25.95%, but again there was much variation in the distribution of the blood groups in different ethnic groups. There was an overall frequency of 3.64% of Rhesus negatives, ranging from 1.4% to 8.72% in different ethnic groups. The results provide basic but useful information concerning many ethnic groups whose blood groups have not previously been reported.

ABO Blood-Group System↗