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Biomedical subjects

A J Hall

Publications and source records attributed to A J Hall.

At least 73 records · Page 4Linked to original sources
PubMed1999

Prevalence of epilepsy in rural Bolivia: a door-to-door survey.

OBJECTIVE: To carry out a door-to-door survey in rural areas of the Cordillera Province, Santa Cruz Department, Bolivia, to determine the prevalence of neurologic diseases (epilepsy, stroke, parkinsonism, and peripheral neuropathy) in a sample of approximately 10,000 inhabitants. METHODS: A team of nondoctor health workers administered a standard screening instrument for neurologic diseases-a slightly modified version of the World Health Organization protocol. All subjects found positive during the screening underwent a neurologic examination. RESULTS: On screening, the authors found 1,130 positive subjects, of whom 1,027 were then investigated by neurologists. On the basis of the definition proposed by the International League Against Epilepsy, we detected 124 epileptic patients (prevalence, 12.3/1,000), 112 of whom had active epilepsy (prevalence, 11.1/1,000) on the prevalence day (November 1, 1994). Peak age-specific prevalence occurred in the 15 to 24-year age group (20.4/1,000). Sex-specific prevalence was higher in women (13.1/1,000) than men (11.4/1,000). Eighty-nine patients (71.8%) underwent a standard EEG recording. Considering both EEG and clinical data, partial seizures were the most common type (53.2%) based on the classification of the International League Against Epilepsy. The mean age at onset was 20.7 years for partial seizures and 13.6 years for generalized seizures. Only 10.5% of patients had received specific treatment for more than 2 months of their life. CONCLUSION: This report on epilepsy prevalence in Bolivia confirms that epilepsy is a major health problem in rural areas of developing countries.

Adolescent↗
PubMed1999

Preparation for a pneumococcal vaccine trial in The Gambia: individual or community randomisation?

In preparation for a large phase-3 trial of pneumococcal polysaccharide/conjugate vaccine among infants in The Gambia, the relative merits of community and individual randomisation were considered. The impact of vaccination might be enhanced in a community randomised trial if there was a substantial 'herd' effect. This might occur if those vaccinated comprise a substantial proportion of potential transmitters of infection. However, there are few data on the sources of pneumococcal infections in The Gambia and with the high degree of mobility of people in The Gambia, it seems unlikely that any herd effect would be strong. In the absence of a herd effect, a community-randomised trial would have lower power for the mortality end-points compared to an individually randomised trial of the same size. In addition, a community-randomised trial might not provide sufficient control against potential confounders and blinding might be difficult to sustain if the vaccine has a strong effect. An individually randomised trial seems a better strategy under the conditions prevailing in The Gambia.

Bacterial Vaccines↗
PubMed1999

Hepatitis B vaccination in infancy in The Gambia: protection against carriage at 9 years of age.

To estimate the efficacy in The Gambia (West Africa) of infant hepatitis B vaccination against infection and carriage with the virus at the age of 9 years. The HBV status of 9-year old children vaccinated in infancy was compared to that of unvaccinated children of the same age. Eight percent of the vaccinated children had been infected by HBV compared to 50% of the unvaccinated control group; HBV carrier status was 0.6 and 10% respectively, resulting in a vaccine efficacy of 83% against infection and of 95% against chronic carriage. The results show that infant vaccination provides a high level of protection at the age of nine years against both HBV infection and chronic carrier status and no booster dose of vaccine is required in the first decade. These findings support the WHO recommendation for the introduction of HBV vaccination into the Expanded Programme on Immunization in Africa.

Carrier State↗
PubMed1999

Lipopolysaccharide induction of tissue factor in THP-1 cells involves Jun protein phosphorylation and nuclear factor kappaB nuclear translocation.

Tissue Factor (TF) gene expression is transiently induced in human monocytic THP-1 cells by lipopolysaccharide (LPS). We characterized the transcription factor complexes binding to the TF gene promoter LPS response element (LRE) (-220 to -172), which contains binding sites for nuclear factor kappaB (NFkappaB) and activator protein 1 (AP1) transcription factors, and examined the nature of the activation of these factors during a 24-h time course of LPS stimulation. We found proteolysis of the cytoplasmic inhibitory protein IkappaBalpha and nuclear translocation of the NFkappaB/Rel family proteins p65 and c-Rel, corresponding to the transient binding of a p65/c-Rel heterodimer to the kappaB-like site of the LRE. AP1 binding to the LRE was found to be constitutive, with the majority of the AP1 complexes being JunD/Fra-2 heterodimers. A change in the activation state of the AP1 complexes was, however, found to be transient, as determined by JunD phosphorylation of AP1 bound to the proximal binding site. This directly correlates to the transient activation of Jun N-terminal kinase (SAPK/JNK). These data indicate that LPS induction of TF gene expression in monocytic THP-1 cells is regulated by both the transient phosphorylation of Jun-family proteins and the nuclear translocation and transient binding of NFkappaB/Rel proteins.

Base Sequence↗
PubMed1999

Organochlorine contaminants in Caspian and harbour seal blubber.

Organochlorine contaminants (pesticides and individual polychlorinated biphenyl congeners, PCBs) were measured in Caspian (Phoca caspica) seal blubber and compared with concentrations in Harbour (Phoca vitulina) seal blubber. Concentrations of total dichlorodiphenyltrichloroethane (DDT) and its metabolites were significantly higher in Caspian seal than Harbour seal samples, whereas PCB congeners were significantly higher in Harbour than Caspian seals. Our finding suggests that Caspian seals are exposed to high levels of DDT pesticides. In contrast, PCBs are circulating in this population at much lower levels than in marine mammals from the North Sea.

Journal Article↗
PubMed1999

Prevalence of antibodies against hepatitis A and E viruses among rural populations of the Chaco region, south-eastern Bolivia.

We conducted a cross-sectional study to determine the seroprevalence of antibodies against hepatitis A and hepatitis E viruses (HAV and HEV) in the population of two rural areas, Camiri and Villa Montes, of the Chaco region, south-eastern Bolivia. HAV antibodies were detected in 461 (94.1%) of 490 serum samples tested, not differing significantly between sexes and study areas. The HAV seropositivity rate (64.7%) was high even in the youngest age group (1-5 years). The prevalence of HEV was 7.3%, with no significant differences between sexes. The prevalence of HEV antibodies in the population of the Camiri area (10.4%) was significantly higher than in the Villa Montes area (4.4%), possibly due to the better quality of drinking water in the Villa Montes area. In the population </= 30 years of age, the HEV seropositivity rate (4.4%) was significantly lower than in the >/= 31 year-old group. This is consistent with findings in other countries. This is the first report of the prevalence of HEV infection in Bolivia.

Adolescent↗
PubMed1999

What level of hepatitis B antibody is protective?

This study assessed the level of vaccine-induced hepatitis B surface antibody that is protective against hepatitis B infection and carriage in The Gambia. Sera from 700 of a cohort of 1041 children vaccinated against hepatitis B in infancy were serially tested for markers of hepatitis B until age 7 years. No absolute level of protection against infection was found, but all children who attained a peak antibody response to vaccination of >=10 IU/L were protected against carriage of hepatitis B surface antigen. Two-thirds of 45 infected children experienced brief infection (determined by loss of core antibody). This transient infection was likely related to surface antibody level. The data support the use of the peak antibody response as the best indicator of protection against carriage and suggest that most infections after vaccination are short-lived.

Antibody Affinity↗
PubMed1999

Diagnosis of pneumococcal pneumonia in epidemiological studies: evaluation in Kenyan adults of a serotype-specific urine latex agglutination assay.

A serotype-specific tube latex agglutination assay for 10 pneumococcal serotypes was evaluated with use of urine samples from 72 Kenyan adults with pneumonia whose blood or lung aspirate cultures were positive for Streptococcus pneumoniae, 203 patients with pneumonia whose cultures were negative for S. pneumoniae, and 101 afebrile controls. Detection thresholds for purified capsular polysaccharide in normal urine ranged from 0.33 to 10 ng/mL. The sensitivity of the assay for the 10 pneumococcal serotypes was 0.57 (95% confidence interval, 0.44-0.70) and was unaffected by human immunodeficiency virus seropositivity, prior antibiotic use, and bacteremic or nonbacteremic status but varied significantly by serotype. Of the pneumococci obtained by culture, 81% were of serotypes (1, 4, 5, 6, 7, 9, 12, 14, 19, and 22) that were included in the antigen assay. Strong simultaneous agglutinations against two different serotypes were found in urine samples from two patients. The specificity of the assay was 0.98 (lower 95% confidence limit, 0.95). Subjective reading of agglutination results introduced variation in specificity that may be inapparent if not formally measured. The assay extended the diagnostic yield in pneumococcal pneumonia by a factor of 2.2 (from 54 diagnoses established by blood culture to 119 established by both methods) and may therefore prove useful in reducing the sample size of epidemiological studies of pneumococcal pneumonia in adults.

Adolescent↗
PubMed1999

Mansonella ozzardi infection in Bolivia: prevalence and clinical associations in the Chaco region.

A cross-sectional survey carried out in the Chaco region of Bolivia showed that 26% (77 of 296) and 0.7% (2 of 298) of the rural population of the Camiri and Villa Montes areas, respectively, harbored Mansonella ozzardi microfilariae (mf). No significant differences were observed between sexes. The lowest prevalence (9%) was in the 0-14-year-old age group, with no children <11 months of age infected. The prevalence increased sharply in the 25-34-year-old age group (32%), and continued increasing in the older age classes. Microfilaremia, ranging from 1 to 305 mf/20 microl of blood, was lowest in 0-14-year-old children (geometric mean concentration = 1.1 mf/20 microl), and increased with age (>100 mf/20 microl in people >44 years old). An expected increasing sensitivity with the blood volume examined was observed. No significant association between clinical symptoms (fever, skin rash, pruritus, headache, lymphedema, elephantiasis, and articular pain) and microfilaremia was observed.

Adolescent↗
PubMed1999

Hepatitis B virus DNA in relation to duration of hepatitis B surface antigen carriage.

This study determined the prevalence and concentration of hepatitis B virus (HBV) DNA in chronic carriers of hepatitis B surface antigen (HBsAg) in The Gambia, West Africa. Ninety-nine young child carriers aged three to four years, 115 older child carriers aged five to 14 years, 71 adult carriers and 105 infected children who were not carriers were included. Detection of HBV DNA was performed by dot blot hybridisation using a radioactive phosphorus (32P) method and by non-radioactive enhanced chemiluminescence (ECL). Chromoscan-3 equipment was used to quantify DNA, and ECL and the 32P method were compared. Sensitivity and specificity of ECL were 95.8% and 100% respectively, with a detection limit of 0.3 pg/microL (0.3 x 10(5) genomic copies) compared to 0.15 pg/microL (0.15 x 10(5) genomic copies) for the 32P-labelled probe. The prevalence of HBV DNA was 74% (74/99) in young carriers, 30% (35/115) in older child carriers and 12.6% (9/71) in adult carriers. The geometric mean (GM) values for HBV DNA were significantly different between age groups (P = 0.031) and HBV DNA, which declined significantly with age (r = 0.16, P < 0.001 for log32P values), ranged from 1.48 pg/microL in young carriers to 0.29 pg/microL in adults over 24 years. The GM value of HBV DNA was related to duration of carriage. Higher values were found in young carriers known to be HBsAg-positive for less than three years compared with adult carriers of at least 20 years' duration. The GM (95% confidence limit [CL]) values were 1.48 pg/microL (1.42, 1.53) and 0.29 pg/microL (0.25, 0.33) respectively. The level of HBV DNA in hepatitis B envelope antigen (HBeAg)-positive carriers was higher than in HBeAg-negative carriers, the GM (95% CL) being 1.23 pg/microL (1.19, 1.27) and 0.34 pg/microL (0.25, 0.42) respectively.

Adolescent↗
PubMed1999

Hepatitis B infection in Bangladeshi mothers and infants.

In order to estimate the relative importance of perinatal transmission of hepatitis B in rural Bangladesh a cross-sectional study was carried out. Paired-serum samples of infants aged 2-8 months old, a group of new born, and their mothers were tested for hepatitis B markers using a commercial ELISA test kit. In total, 107 (32.4%) positive for HBcAg, 18 (5.4%) for HBsAg, and 4 (1.2%) for HbeAg. Of the infants, 35 (10.5%) positive for HBcAg, 1 (0.3%) for HBsAg, and none for HBeAg. Of the 18 HBsAg positive mothers, 4 (22%) were HBeAg positive. All 14 children of mothers who were HBeAg negative were negative for HBsAg. Only one out of four (25%) of children of HBeAg positive mothers were HBsAg carriers (8 months old), and in three children transmission did not occur (two 8 months, one 6 months old). This survey indicates that hepatitis B is prevalent in rural Bangladesh and that the perinatal transmission mode may be relatively low.

Bangladesh↗
PubMed1998

Domestic pets as risk factors for alveolar hydatid disease in Austria.

To identify the risk of pet ownership (i.e., cats and dogs) for alveolar echinococcosis caused by Echinococcus multilocularis, the habits and activities of 21 patients (histologic confirmation or positive serology with corresponding evidence on an ultrasonogram, radiograph, or computed tomography scan) in Austria during the period 1967-1997 were compared with the habits and activities of 84 controls matched by sex, age, and residence. Cat ownership (odds ratio (OR) = 6.47, 95% confidence interval (CI) 1.54-27.29) and hunting (OR = 7.83, 95% CI 1.16-52.77) were independent risk factors associated with alveolar hydatid disease. The study is not in agreement with the hypothesis that eating mushrooms or certain wild berries which grow near the ground are the main risk factors for acquiring this disease. No other behavior patterns or activities studied were identified as risk factors.

Adolescent↗