An epidemiological assessment of blood pressure determinants in an adolescent population of Nigerians

An epidemiological assessment of blood pressure determinants in a random sample of 254 Nigerian adolescents aged 6-17 years in Benin City, Nigeria, was conducted. None of the adolescents reported cigarette smoking. Only 2.6% of the males and 0% of the females were alcohol users. Socio-economic status of the children according to parental education revealed that approximately 23% of the mothers and 9.8% of the fathers received less than a secondary (high school) education. At the other end of the education spectrum, a college education was received by 64.1% and 30.8% of the fathers and mothers, respectively. Two percent of the females and 1.3% of the males either had systolic blood pressures of greater than or equal to 140 mmHg or diastolic blood pressures of greater than or equal to 90 mmHg. No significant blood pressure differences existed between the two sexes. Among the males, it was demonstrated that age, body mass index, and heart rate were significant independent predictors of systolic blood pressure, explaining 49% of the variance. Forty-seven per cent of systolic blood pressure variance was explained by age and heart rate, for females. It was interesting to note that age was the only independent predictor of diastolic blood pressure for both males and females after control for heart rate and body mass index.     

Acquisition and maintenance of intravenous cocaine self-administration in Lewis and Fischer inbred rat strains

Lewis and Fischer inbred rat strains differ in behavioral and biochemical responses to psychoactive drugs: Lewis rats show greater behavioral responses to psychoactive drugs than Fischer rats and they fail to show biochemical adaptations in the mesolimbic dopamine system after chronic drug exposure, in contrast to Fischer and outbred rats. This suggests that Fischer and Lewis rats may differ in the initial, reinforcing effects of psychoactive drugs, but not in responses seen after the exposure that occurs with maintenance of drug-reinforced behavior. Thus, the present study tested whether these strains differ in acquisition or maintenance of intravenous cocaine self-administration. Acquisition of cocaine self-administration was examined in separate groups that were allowed 15 days to acquire the operant at one of three cocaine doses (0.25, 0.5, or 1.0 mg/kg/infusion). Compared to Fischer rats, Lewis rats acquired cocaine self-administration after fewer training trials and at lower doses. After maintenance, both strains showed characteristic extinction responding with saline substitution and dose-related responding to cocaine, although Fischer rats tended to show higher response rates. Finally, cocaine plasma levels, obtained after an intravenous cocaine infusion (1.0 mg/kg), showed no strain differences suggesting that the strain difference in acquisition was not due to cocaine pharmacokinetics. These strain differences in acquisition of cocaine self-administration may be related to reported strain differences in the mesolimbic dopamine system. Further, because acquisition of drug self-administration is an animal model of vulnerability to drug addiction, these inbred strains may be useful to study factors underlying such vulnerability.     

Relationship between measles HI titers and an MS susceptibility gene

Summary Recently published studies of formal linkage analyses strongly suggest that a multiple sclerosis susceptibility (MSS) gene is linked to the HLA region of the sixth chromosome. The objective of this analysis was to investigate whether or not the gene has any demonstrable relationship to the immune status with regard to measles within members of multiple-case MS families. Family members were HLA-typed, and levels of antibodies to measles were determined using the hemagglutination inhibition assay. Since a specific, HLA-defined haplotype within each family is presumably a marker for the MSS gene, family members were characterized as either carrying [(+) controls] or not carrying [(–) controls] the MSS gene by the presence of this specific haplotype. Twenty families were entered into the analyses. Results revealed that the mean titer to measles was not different between (+) and (–) controls, and that MS cases had significantly higher titers than both control groups combined.

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Zusammenfassung Vor kurzem veröffentlichte Studien über die formale Verbindungs-Analyse lassen sehr stark vermuten, daß ein Anfälligkeitsgen für Multiple Sklerose (MSS) mit der HLA-Region des sechsten Chromosoms verbunden ist. Es war das Ziel der Analyse, zu untersuchen, ob das Auftreten dieses Gens irgendeine nachweisbare Verbindung mit dem Immunestatus in bezug auf Masern unter den Mitgliedern von Familien mit mehrfachen Fällen von MS hat. Die Familienmitglieder waren HLA-Typen, und die Anzahl der Antikörper für Masern wurde durch die Hämagglutination-Inhibition-Probe bestimmt. Da ein spezifischer, HLA-bestimmter Haplotype innerhalb jeder Familie als Kennzeichen für das MSS-Gen angenommen wird, wurden die Familienmitglieder als Träger [(+)-Kontrolle] oder Nichtträger [(–)-Kontrolle] des MSS-Gens durch das Auftreten dieses spezifischen Haplotypen bestimmt. Zwanzig Familien nahmen an der Analyse teil. Die Resultate zeigten, daß der Durchschnittstiter für Masern zwischen den (+)- und (–)-Kontrollen nicht unterschiedlich war, und daß die MS-Fälle wesentlich höhere Titer hatten als beide Kontrollgruppen zusammen.

     

Hormonal factors and risk of ovarian germ cell cancer in young women

No previous controlled studies of ovarian germ cell tumours have been reported; however the tumour is similar to germ cell testicular cancer in terms of histology, age-specific incidence rates (i.e. highest rates in young adulthood), and secular trends of increasing incidence. The investigation was designed to determine if maternal hormonal factors which have been found to increase the risk of testis cancer in male offspring are also risk factors for the ovarian tumour. The analysis is based on 73 cases diagnosed before age 35 and 138 age-race matched controls. The cases were identified by tumour registries in Los Angeles (1972-84) and Seattle (1974-84) and controls were selected from friends and/or neighbourhood residents. Interviews were conducted on the telephone with mothers of cases and controls. The primary finding was that mother's use of exogenous hormones (including the hormonal pregnancy test, DES or other supportive hormones, and inadvertant use of oral contraceptives after conception) increased risk (Odds ratio, OR = 3.60, 95% CL = 1.2-13.1). Other maternal factors associated with elevated risk were high pre-pregnancy body mass (OR = 2.7, 95% CL = 1.0-7.6), more rapid achievement of regular menstruation after menarche (OR = 1.8, 95% CL = 0.9-3.8), and age at index pregnancy under 20 (OR = 2.8, 95% CL = 1.0-10.7). In conclusion, these results support findings from testis cancer studies regarding a hormonal aetiology for germ cell tumours, and a mechanism by which oestrogen may affect the germ cells is proposed.     

Computer simulation of the effectiveness of male-linked translocations for the control of Anopheles albimanus Wiedemann.

A deterministic simulation model was used to establish the potential value of releasing male-linked translocation heterozygotes as a control measure for Anopheles albimanus Wiedemann. Theoretical population reductions exceeding 90% were obtained within 90 and 120 days after releases at initial ratios of 5 translocation males (TM): 1 normal male (NM) and 1 TM: 1 NM, respectively. Additional simulations emphasized the importance of the need for a method that would eliminate females from the release material. Releases containing 15% females were less effective than those with none. When a malaria subroutine was included in the model, the calculations showed that all the theoretical releases greatly reduced the number of malaria-infective females and therefore would have a profound effect on transmission of the disease. The number of malaria-infective females present was eliminated completely when only translocation males were released; however, a small number were present when the releases contained 15% females. Male-linked translocation males required longer periods of time to bring about population control than males that were completely sterile.     

Schistosomiasis in Omo National Park of southwest Ethiopia.

Schistosomiasis mansoni infection was found in more than 50 tourists who had visited Omo National Park, Ethiopia, and bathed and swum in the Mui River. A survey revealed Schistosoma mansoni infection in 41% of Park residents and in 33% of the neighboring Suri people. Eggs were found in stools and adult worms at autopsy of wild Papio anubis and Cercopithecus aethiops. Trematode larvae were found in 27% of Biomphalaria pfeifferi snails found in the Mui River. The source of the disease and the implications of its spread with the future development of the Omo Valley are discussed.     

Association of clozapine-induced weight gain with a polymorphism in the leptin promoter region in patients with chronic schizophrenia in a Chinese population

Weight gain is a problem commonly encountered with antipsychotic treatment and has become more apparent with increasing use of the newer atypical antipsychotics. The adipocyte-derived hormone, leptin, has been associated with body weight and energy homeostasis, and abnormal regulation of leptin could play a role in weight gain induced by antipsychotics. We investigated whether a leptin gene promoter variant affected weight gain after long-term treatment with clozapine in chronic schizophrenia. Leptin G2548A polymorphism was genotyped in 102 Chinese Han inpatients with chronic schizophrenia treated with clozapine. Weight gains, expressed as change in body mass index (BMI), were monitored after long-term clozapine treatment. We found a significant relationship between the 3 leptin G/A genotypes and mean BMI gain (F(2,99) = 3.35, P = 0.039, r(2) = 0.09). Moreover, genotype had a strong effect on BMI gain in male (P = 0.004, r(2) = 0.16), but not in female patients (P > 0.05). Thus, variation in the leptin gene may be a risk factor for weight gain in male patients with schizophrenia on long-term clozapine treatment.     

Ancient DNA reveals late survival of mammoth and horse in interior Alaska

Causes of late Quaternary extinctions of large mammals (“megafauna”) continue to be debated, especially for continental losses, because spatial and temporal patterns of extinction are poorly known. Accurate latest appearance dates (LADs) for such taxa are critical for interpreting the process of extinction. The extinction of woolly mammoth and horse in northwestern North America is currently placed at 15,000–13,000 calendar years before present (yr BP), based on LADs from dating surveys of macrofossils (bones and teeth). Advantages of using macrofossils to estimate when a species became extinct are offset, however, by the improbability of finding and dating the remains of the last-surviving members of populations that were restricted in numbers or confined to refugia. Here we report an alternative approach to detect ‘ghost ranges’ of dwindling populations, based on recovery of ancient DNA from perennially frozen and securely dated sediments (sedaDNA). In such contexts, sedaDNA can reveal the molecular presence of species that appear absent in the macrofossil record. We show that woolly mammoth and horse persisted in interior Alaska until at least 10,500 yr BP, several thousands of years later than indicated from macrofossil surveys. These results contradict claims that Holocene survival of mammoths in Beringia was restricted to ecologically isolated high-latitude islands. More importantly, our finding that mammoth and horse overlapped with humans for several millennia in the region where people initially entered the Americas challenges theories that megafaunal extinction occurred within centuries of human arrival or were due to an extraterrestrial impact in the late Pleistocene.