First cases of a pestilence more malignant.
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Biomedical subjects
Publications and source records attributed to R G Hendrickse.
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Similarities between the geographical and climatic prevalences of kwashiorkor and of exposure to dietary aflatoxins, and between the biochemical, metabolic and immunological derangements in kwashiorkor and those in animals exposed to aflatoxins, prompted investigation of the associations between kwashiorkor and aflatoxins. Studies in Africa in the 1980s indicated a role for these toxins in the pathogenesis of the disease. Paediatric cases of kwashiorkor are less prone to severe Plasmodium falciparum malaria than normal children. In mice infected with P. berghei, aflatoxin exposure inhibits parasite growth and ameliorates morbidity. Aflatoxins occur in < or = 40% of samples of breast milk from tropical Africa, usually as low concentrations of the relatively non-toxic derivatives of aflatoxin B1 (AFB1) but sometimes as high concentrations of the very toxic AFB1. This could explain kwashiorkor in breast-fed babies. Aflatoxin exposure occurs in > or = 30% of pregnancies in tropical Africa and the toxins are often in cord blood, sometimes at extremely high concentrations. Aflatoxins are now incriminated in neonatal jaundice and there is circumstantial evidence that they cause perinatal death and reduced birthweight. Aflatoxin-induced immunosuppresion may explain the aggressive behaviour of HIV infection in Africa. There are similarities between observations on HIV cases in Africa and those on heroin addicts in Europe, where 'street' heroin is frequently contaminated with aflatoxin. Aflatoxins were found in 20% of random urine samples from heroin addicts in the U.K. and the Netherlands. Aflatoxins have also been incriminated in episodes of food poisoning which have been associated with serious morbidity and mortality, particularly among young children.
Breast milk from 113 mothers in two 'Under-Five Clinics' in the Southern Province of Sierra Leone, namely, Njala and Bo, were examined for their mycotoxin content. Only 10 were mycotoxin-free. Eighty-eight per cent of samples contained various aflatoxins and 35% contained ochratoxin A (OTA). Few samples (15%) had a single mycotoxin. Thirty-six (32%) had two mycotoxins and 50 (40%) had three or more. The occurrence of OTA in combination with various aflatoxins was recorded. It is concluded that infants in Sierra Leone are exposed to OTA and aflatoxins at levels which in some cases far exceed those permissible in animal feed in developed countries.
Analysis of 64 cord blood samples from pregnant women in Sierra Leone revealed the presence of ochratoxin A (OTA) and aflatoxins in 25% and 58% of samples, respectively. Of the eight maternal blood samples collected during delivery, one contained OTA and aflatoxins were detected in six. There was no relationship between mycotoxins in maternal and cord blood. The effect these toxins might have had on the birthweight of infants is discussed.
Two prospective studies were undertaken to determine a possible relationship between perinatal aflatoxin exposure and neonatal jaundice. First, cord blood samples from 37 neonates who subsequently developed jaundice and from 40 non-jaundiced (control) babies were analysed for six major aflatoxins and aflatoxicol. Peripheral blood samples of both groups were also analysed postnatally for aflatoxins. In a second study, serum aflatoxin levels of 64 jaundiced neonates admitted from outside the hospital were compared with levels in 60 non-jaundiced control babies. Aflatoxins were detected in 14 (37.8%) cord blood samples of jaundiced neonates and in nine (22.5%) of the controls. The mean cord aflatoxin concentration was highest in jaundiced neonates with septicaemia, but the difference was not statistically significant. The frequency of detection of aflatoxins in peripheral blood was not significantly different in jaundiced and non-jaundiced babies. Aflatoxins were detected in the blood of over 50% of neonates with jaundice of 'unknown' aetiology. There was no correlation between severity of hyperbilirubinaemia and serum aflatoxin levels. Further studies are needed to determine the extent of pre- and postnatal exposure to aflatoxin in Nigerian infants and the effects of such exposure on fetal and neonatal health.
This study set out to investigate the prevalence of naphthols and aflatoxins in the sera of babies with neonatal jaundice and their mothers in order to determine whether they contribute to the occurrence of unexplained neonatal jaundice in Ibadan. Blood was obtained from 327 jaundiced neonates and 80 of their mothers, and 60 non-jaundiced controls and seven of their mothers admitted to hospital between April 1989 and April 1991. Blood group, bilirubin concentration, erythrocyte G6PD status, aflatoxin and naphthol concentrations in blood were measured. Altogether, 30.9% of the jaundiced neonates were G6PD-deficient, compared with 13.3% of controls (chi 2 = 6.88; p = 0.009). Aflatoxins were detected in 27.4% of jaundiced neonates, 17% of their mothers, 16.6% of controls and 14.4% of control mothers. Naphthols were detected in 7.2% of jaundiced babies, 6.3% of their mothers, 6.25% of control babies and 14.4% of their mothers. Analysis of the data revealed that either G6PD deficiency or the presence of any serum aflatoxin is a risk factor for neonatal jaundice; odds ratio were 2.97 (95%) confidence intervals (CI): 1.31-6.74) and 2.68 (CI: 1.18-6.10), respectively. This study demonstrates that G6PD deficiency and/or the presence of serum aflatoxins are risk factors for neonatal jaundice in Nigeria. Aflatoxins are an additional risk factor not previously reported.
This investigation sought to determine whether splenic lymphocytes obtained from Balb/C mice exposed to aflatoxin B1 (AFB1) showed any ultrastructural changes which could account for the immunodysfunction attributable to aflatoxins. Lymphocytes obtained from Balb/C mice administered aflatoxin B1 in olive oil daily for three weeks were studied using both transmission and scanning electron microscopy. The lymphocytes demonstrated ultrastructural changes primarily in the mitochondria where marked internal dissociation of the cristae was revealed by transmission electron microscopy. All other cellular organelles were unaffected. No significant alterations in external structure were observed under scanning electron microscopy. The findings of this study indicate that AFB1 administration does not affect the surface topography of lymphocytes, but AFB1, by causing extensive mitochondrial damage, may affect the way in which these cells function. This could be a possible explanation for the immunodysfunction associated with AFB1.
Widespread use of napthol-containing compounds and frequent contamination of foods by aflatoxins occurs in Nigeria. Napthols cause haemolysis and aflatoxins are hepatotoxic. A study was carried out to determine the extent of fetal exposure to these compounds and their influence on birthweight. Cord blood samples were collected at delivery from 625 babies and their sera were analysed for aflatoxins and naphthols. Mothers' histories and babies' weights were recorded. Naphthols were detected in 6.9% and aflatoxins in 14.6% of serum samples. No correlation was found between the presence of either compound and birthweight. Reported exposure to naphthalene-containing compounds was not related to detection of serum naphthol. Results show considerable fetal exposure to these potentially toxic compounds in Ibadan, Nigeria.
Nigeria is a very high risk area for primary hepatocellular carcinoma and this is the first study to utilize measurements of both hepatitis B virus status and aflatoxin levels in the same patients to determine the role of these factors in the causation of liver cancer in this environment. We have shown that there is a higher prevalence of hepatitis B surface antigen (P < 0.005) and higher 'pathologic' serum levels of aflatoxins (P < 0.05) in patients with primary hepatocellular carcinoma than in matched controls. It is considered that the results of this study may strengthen the hypothesis that hepatitis B virus may be an important aetiological factor in the development of primary hepatocellular carcinoma. Further work is in progress to correlate the level of aflatoxin serum albumin adducts with liver damage in order to assess the value of the albumin adduct as a marker of risk of liver cancer development.
The purpose of this study was to screen for the presence of hepatitis B surface antigen and aflatoxins in the sera of 100 non-hospitalized individuals from the rural population of Igbo-Ora and 89 non-hospitalized individuals from the urban population of Ibadan, Nigeria. Hitherto, such a study as this has not been undertaken in this environment. The proportions of hepatitis B surface antigen carriage and serum 'pathologic' levels of aflatoxins were high (47-49%, 8.2-9.0% respectively) but varied very little between the two different populations sampled. These findings indicate that determined efforts should be instituted to reduce or eliminate hepatitis B virus infection and aflatoxin contamination of high risk foodstuffs from this environment.
The effects of a short-term in vivo administration of two liver tumour promoters (phenobarbital and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane on rat liver endoplasmic reticulum Ca(2+)-ATPase were investigated. The specific activity values of this membrane-bound enzyme significantly decreased (P less than 0.01) by 51% for phenobarbital-treated rats and by 48% for 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane-treated rats compared with control animals. The depression of liver endoplasmic reticulum Ca(2+)-ATPase appears to be a manifestation of the toxicological effect of tumour promoters.
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Aflatoxins have been incriminated, mainly on circumstantial evidence, in hepatocellular carcinoma, acute hepatic failure and Reye's syndrome, but other possible effects of continuous or intermittent dietary exposure to aflatoxins, which occurs widely in the tropics, have received little study. Over the past 10 years evidence has steadily accumulated that incriminates aflatoxins in the aetiology of kwashiorkor, a widespread and serious disorder of children in the tropics, previously believed to be caused by protein deficiency. Investigation of human breast milk, undertaken initially to elucidate the pathogenesis of kwashiorkor in breastfed infants, has revealed widespread and serious exposure to aflatoxins from this source. Extension of these studies to pregnant women, in turn, revealed widespread and serious prenatal aflatoxin exposure. In laboratory and farm animals, such exposure has serious implications for immune and hepatic functions, and is detrimental to growth and development. Recent analysis of heroin samples show that heroin addicts may also be exposed to these toxins. These findings show that human exposure to aflatoxins may begin prenatally, persist during breastfeeding, and continue into adult life. It is postulated that aflatoxins (i) play a role in the aetiology of kwashiorkor, (ii) increase neonatal susceptibility to infection and jaundice, (iii) increase childhood susceptibility to infections and malignant disease, (iv) compromise immune responses to prophylactic immunisations and (v) may play a role in the pathogenesis of diseases in heroin addicts. There are indications also that acute, fatal aflatoxin poisoning which masquerades as 'hepatitis' may occur more frequently than is currently appreciated.
A group of five children with kwashiorkor, seven with marasmic kwashiorkor and one underweight child were given an aflatoxin-free diet consisting of maize meal and milk powder. Blood specimens were collected on admission; on day 4 and 10, 24 hour urine and stool samples were collected for the first ten days. Serum, urine and stool samples were analysed for aflatoxins using high performance liquid chromatography with fluorescent detection, after various extraction and clean-up procedures. The children with kwashiorkor and marasmic kwashiorkor excreted aflatoxins in stools for up to 9 and 6 days after admission respectively. No aflatoxins were detected in the stools or urine of the underweight child. In kwashiorkor, urinary excretion ceased after 2 days, while in marasmic kwashiorkor urinary excretion persisted for 4 days. In stools, B1 was the type of aflatoxin detected most frequently in kwashiorkor and least frequently in marasmic kwashiorkor. Aflatoxin M2 was frequently detected in the stools of both groups of children. Estimates of the total amount of aflatoxin excreted by kwashiorkor and marasmic kwashiorkor indicate that these children were harbouring up to 4 micrograms/kg body weight at the time of admission. These findings establish that aflatoxins accumulate in body fluids and tissues in kwashiorkor and marasmic kwashiorkor which is only slowly eliminated.
Haematological and iron parameters, measured in 907 children aged from 6 months to 5 years in rural Gambia at the start of the rainy season, differed from those in American reference populations as follows: mean haemoglobin levels were much lower at ages 1 and 2 years and mean levels of mean corpuscular volume (MCV) were lower at all ages (at age 1 year mean haemoglobin was 11.2 g/dl and mean MCV 68.2 fl); in a sample of 249 children randomly selected from the whole study population, mean serum iron levels were similar but mean transferrin saturation and mean serum ferritin levels were lower, especially at ages 1-3 years (at age 1 year mean serum iron was 11.1 mumol/l, mean transferrin saturation 16.9%, and geometric mean serum ferritin 8.8 ng/ml. A total of 213 children (23%) whose haemoglobin and mean corpuscular volume were both less than the 3rd percentile of the reference population received oral iron or placebo from their mothers during the rainy season when malaria transmission is maximal. Mean levels of haemoglobin, mean corpuscular volume, serum iron, transferrin saturation and serum ferritin rose in the iron-treated group and fell in the placebo group at all ages, except under 1 year for serum ferritin, to produce significant differences between the groups by the end of the study. Total iron-binding capacity showed no significant changes during the study. We concluded that oral iron given by the mother during the rainy season can be used to treat iron-deficiency anaemia in Gambian children who would otherwise become more anaemic.