Finding and using rural aging data: an international perspective.

This article reports on a workshop in which participants identified sources of data on rural aging. Such sources are typically part of larger data collection efforts or special aging studies with large rural components. Finding and using data on rural aging are not only two different processes but they also face somewhat different obstacles and the solutions are likewise different. The workshop addressed both of these issues. Participants shared many innovative and creative means for collecting, finding and adapting more general data sources, and analyzing and using these data, to further our understanding of rural aging phenomena.

Acquisition of species-specific O-linked carbohydrate chains from oviducal mucins in Rana arvalis. A case study.

The extracellular matrix surrounding amphibian eggs is composed of mucin-type glycoproteins, highly O-glycosylated and plays an important role in the fertilization process. Oligosaccharide-alditols were released from the oviducal mucins of the anuran Rana arvalis by alkali-borohydride treatment in reduced conditions. Neutral and acidic oligosaccharides were fractionated by ion-exchange chromatographies and purified by HPLC. Each compound was identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) spectrometry, NMR spectroscopy, electrospray ionization-tandem mass spectroscopy (ESI-MS/MS) and permethylation analyses. This paper reports on the structures of 19 oligosaccharide-alditols, 12 of which have novel structures. These structures range in size from disaccharide to octasaccharide. Some of them are acidic, containing either a glucuronic acid or, more frequently, a sulfate group, located either at the 6 position of GlcNAc or the 3 or 4 positions of Gal. This latter sulfation is novel and has only been characterized in the species R. arvalis. This structural analysis led to the establishment of several novel carbohydrate structures, demonstrating the structural diversity and species-specificity of amphibian glycoconjugates.

Structural analysis of 13 neutral oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Rana temporaria.

Amphibian eggs are always surrounded by an extracellular matrix, named the jelly coat. This is mainly composed of a highly O-glycosylated, mucin-type glycoprotein. This work has consisted of isolating O-linked neutral oligosaccharides from oviducal mucin of Rana temporaria, with a view to determining their primary structure. Hence, these carbohydrate chains have been released by alkaline borohydride treatment leading to stable glycans. The oligosaccharide-alditols have been purified by ion-exchange chromatography and separated by HPLC. The primary structure of 13 of these carbohydrate chains have been obtained by 1D/2D 1H-NMR spectroscopy and methylation analyses, in combination with MALDI-TOF mass spectroscopy. The results confirm what has been observed for six other amphibians about the species-specificity of the carbohydrate moieties and their likely involvement in the species-specific gamete recognition.

Structural analysis of 20 oligosaccharide-alditols released from the jelly coat of Rana palustris eggs by reductive beta-elimination characterization of the polymerized sequence [Gal(beta1, 3)GalNAc(alpha1-4)]n.

The eggs of amphibians are surrounded by three to eight layers of jelly coats. This extracellular matrix is mainly composed of hydrated mucin-type glycoproteins. These highly glycosylated molecules are synthesized by oviduct and play an important role in the fertilization process. Recent structural analyses have shown the strict species-specificity of the O-linked oligosaccharides which constitute 60-70% of these oviducal mucins. Consequently, these carbohydrate chains represent new phenotypic markers, and from a biological point of view, can influence parasite tropism or can be involved in species-specific interaction of gametes. The primary structure of 20 oligosaccharide-alditols, released by alkali/borohydride treatment from the mucin of Rana palustris egg jelly coats, was established by 1H and 13C-NMR analysis. Thirteen of these components possess new structures and the polymerization of the sequence Gal(beta1-3)GalNAc(alpha1-4) characterizes the species-specificity of R. palustris.

Preimmunization epidemiology of hepatitis B virus infection in South African children.

The prevalence of hepatitis B surface antigen (HBsAg) was determined in a community-based, cross-sectional, age-stratified sample of children from 0 to 6 years of age (n = 2,299) from the Eastern Cape Province of South Africa. The purpose of the study was to investigate the epidemiology and the age of acquisition of hepatitis B virus (HBV) infection in children, thus providing a preimmunization baseline measure of this infection in the population targeted for HBV immunization in South Africa. Overall, 10.4% (95% CI, 9.2-11.7) of the children tested were HBsAg-positive. There was a high rate of positivity in the 0-6- and 7-12-month age groups at 8.1% (95% CI, 5.5-11.7) and 8.9% (95% CI, 6.1-12.7), respectively, suggesting a higher rate of early acquisition of this infection than previously reported in South Africa. The proportion of HBsAg-positive children increased significantly with increasing age (chi2trend = 5.9, df = 1, P = 0.02), reaching 15.7% in the 61-72-month age group. This is the highest rate of HBV infection reported in community-based children from South Africa, indicating a significant burden of this infection. The difference in HBsAg prevalence between urban and rural children was not statistically significant (chi2 = 0.32, df = 1, P = 0.57). There was also no difference in positivity between males (10.5%; 95% CI, 8.7-12.5) and females (9.8%; 95% CI, 8.1-11.7), (chi2 = 0.006, df = 1, P = 0.94). This study provides the most recent preimmunization, community-based baseline investigation of the epidemiology of HBV infection in children targeted for universal immunization in South Africa.

Interaction between lectins and neoglycoproteins containing new sialylated glycosynthons.

Neoglycoconjugates are useful tools to study carbohydrate/protein interactions. In order to discover new lectins, to define their fine specificity or to study their intracellular trafficking, there is a need for neoglycoconjugates containing complex oligosaccharides. We recently set up a simple way to transform native oligosaccharides into glycosynthons. The present paper describes i) the synthesis of such glycosynthons starting with sialylated oligosides, ii) the preparation of sialylated neoglycoproteins and iii) their binding to sialic acid-specific lectins assessed by surface plasmon resonance experiments.

Does hepatitis GB virus-C infection cause hepatocellular carcinoma in black Africans?

The newly cloned and characterized hepatitis GB virus-C (HGBV-C), which is the same virus as the independently discovered hepatitis G virus, has a global distribution, is transmitted parenterally, and causes chronic viremia. The pathological consequences of infection with HGBV-C are uncertain, and its hepatocarcinogenic potential is unknown. We used a case-control format to compare the prevalence of HGBV-C infection in 167 southern African blacks with hepatocellular carcinoma (HCC) and 167 race-, age-, and sex-matched hospital-based control subjects, and to test for possible interactive effects between this virus and hepatitis B and C viruses in the development of the tumor. The presence of HGBV-C ribonucleic acid was detected in serum samples by reverse transcription, amplification of the resulting complementary deoxyribonucleic acid by the polymerase chain reaction (PCR), and Southern hybridization using a probe from the NS3/helicase region of the genome. Serum samples were also tested for the presence of hepatitis B virus surface antigen, antibodies to hepatitis C virus, and hepatitis C virus ribonucleic acid. Individuals infected with HGBV-C did not have an increased relative risk of developing HCC (relative risk 0.9; 95% confidence limits 0.5, 1.7). Moreover, co-infection with HGBV-C did not further increase the risk of tumor development in patients who were chronically infected with hepatitis B and/or C viruses. HGBV-C is unrelated to hepatocellular carcinoma development in black Africans.

The relative roles of hepatitis B and C viruses in the etiology of hepatocellular carcinoma in southern African blacks.

BACKGROUND & AIMS: Epidemiological studies have shown the relative roles of hepatitis B and C viruses in hepatocarcinogenesis to vary considerably among populations. The aim of this study was to define the independent and interactive roles of the two viruses in the genesis of hepatocellular carcinoma in southern African blacks. METHODS: Blood samples were taken from 231 black patients with hepatocellular carcinoma and matched controls treated at four Johannesburg hospitals. These were tested for hepatitis B surface antigen, antibodies to hepatitis C virus, and hepatitis C virus RNA. RESULTS: Relative to individuals without serological evidence of hepatitis B or C infection, those positive for hepatitis B surface antigen alone had a statistically significant 23.3-fold increased risk for hepatocellular carcinoma, whereas those positive for hepatitis C serology alone had a statistically significant risk of 6.6. A synergistic effect on risk was evident when both hepatitis B and C markers were present (relative risk, 82.5). Hepatitis B virus alone is estimated to cause 43% of hepatocellular carcinoma in southern African blacks, hepatitis C alone 5%, and coinfection with the two viruses 20%. CONCLUSIONS: Hepatitis B virus plays a predominant role in hepatocellular carcinogenesis in southern African blacks, with hepatitis C virus responsible for a smaller proportion of cases. Coinfection with the two viruses carries a synergistic risk of hepatocellular carcinoma formation.

Hepatocarcinogenic potential of genotype 5 of hepatitis C virus.

Evidence is emerging that hepatitis C virus genotypes have different carcinogenic potentials. The hepatocarcinogenicity of genotype 5, the predominant subtype in hepatitis C virus isolates in South Africa, is not known. We have compared the prevalence of genotype 5 of hepatitis C virus in 44 southern African blacks with hepatitis C virus-related hepatocellular carcinoma with that in a comparable group of patients with hepatitis C virus-induced chronic liver disease (cirrhosis or chronic hepatitis) in the absence of cancer. Hepatitis C virus serotypes 1 to 6 were identified by measuring type-specific antibodies to NS4-derived peptide antigens. Serotype 5 was present in 48% (21/44) of the patients with hepatocellular carcinoma and 37% (15/41) of those with liver disease in the absence of hepatocellular carcinoma, an insignificant difference. Although the numbers of the other genotypes were small, the differences in the prevalence rates of these serotypes between the two groups of patients were also not significant. We conclude that genotype 5 of the hepatitis C virus is neither more nor less carcinogenic than other genotypes found in isolates in South Africa.

Hepatocellular carcinoma in urban born blacks: frequency and relation to hepatitis B virus infection.

Chronic hepatitis B virus infection is far less common in urban born than in rural born southern African blacks, who also have a high incidence of hepatocellular carcinoma. A case-control study was carried out to determine the relative frequency of hepatocellular carcinoma and its relation to hepatitis B virus infection in urban born blacks. Three hundred and ninety two black patients with hepatocellular carcinoma and matched controls seen at two city hospitals were classified by questioning as urban born or rural born. The ratio of rural born to urban born blacks among the controls was 1.1:1.0 (207/185), whereas in the patients with cancer the ratio was 4.8:1.0 (324/68) (p less than 0.0001). Analysis of the prevalence of hepatitis B markers in 62 urban born and matched rural born blacks with hepatocellular carcinoma showed no differences in the frequency of current or past hepatitis B virus infection. It is concluded that urban born blacks are less likely than rural born blacks to develop hepatocellular carcinoma, but when they do the tumour is equally likely to be related to infection with hepatitis B virus. The findings lend further support to an important role for chronic hepatitis B virus infection in the aetiology of hepatocellular carcinoma.

Limitations of enzyme immunoassay tests for detection of HTLV-III/LAV antibodies.

A commercial enzyme immunoassay (EIA) kit was compared with an immunofluorescence test for the detection of antibodies directed against human T-cell lymphotropic virus type III (HTLV-III). The EIA kit is recommended for the screening of blood and plasma products only and is not suitable for diagnostic purposes because of the problem of nonspecific reactions. It is also recommended that the EIA kit not be used for screening immunoglobulin preparations for anti-HTLV-III antibodies because of the problem of false-positive reactions.

Diagnosis of viral hepatitis. Experience in a South African laboratory.

Analysis of results in 14 250 specimens assayed for the diagnosis of viral hepatitis at one laboratory shows that hepatitis A and B are endemic in South Africa and that an important part of the diagnostic workload of virology laboratories now consists of determining their markers. The results fall into previously described patterns, but some anomalies were detected which indicated that unintentional parenteral transfer may occur even when testing for hepatitis B markers has been done. Furthermore, simultaneous hepatitis A and B infections or superinfection of carriers were found to be not as uncommon as one would expect. A progression flow-chart was drawn up to show how the markers change in retested patients, and this may serve as a guide for clinicians dealing with viral hepatitis in South Africa.

Tick-bite fever in South Africa. The occurrence of severe cases on the Witwatersrand.

Tick-bite fever, the variety of tick typhus occurring in southern Africa, is caused by Rickettsia conori var. pijperi and is transmitted by hard or ixodid ticks. It is usually a mild disease, especially in children and young adults, but in middle-aged and elderly patients (and sometimes in young adults) it may assume a severe form. This is characterized by high fever, severe headache, delirium, stupor and occasionally coma, and a profuse maculopapular rash which becomes haemorrhagic and is associated with petechiae in the skin and later, but rarely, by the development of gangrene of the fingers and toes. During these severe attacks the central nervous system may be involved and marked disorders of liver and kidney function sometimes lead to kidney failure and the need for treatment and dialysis in an intensive care unit. Three illustrative cases are described in which diagnosis was delayed. One patient died; 2 patients responded to administration of tetracycline. The danger of allowing tick-infested dogs onto one's bed is stressed. Infections transmitted by dog ticks tend to be more severe than those acquired via ticks from the bushveld, possibly because they so often occur in middle-aged and elderly patients. Serological tests have recently indicated that there are antigenic differences between 'suburban' and 'bushveld' strains; these clearly require further study.

A serological investigation of Mycoplasma pneumoniae infection on the Witwatersrand.

Sera from patients with respiratory disease were examined for antibody to Mycoplasma pneumoniae by complement fixation test. During the study period of about 6 years, a 3-year cycle of infection was observed, which coincided with some epidemics in the UK and USA, suggesting the possibility of an approximately simultaneous world-wide spread. The epidemics lasted about 18 months each, during which the incidence of infection was over 10 times that of the interepidemic periods.