Exposure to hepatitis B virus among South African health care workers--implications for pre-immunisation screening.

Vaccination of health care workers is highly effective in preventing occupationally acquired hepatitis B virus (HBV) infection, but cost is a major factor impeding routine immunisation programmes. Pre-vaccination serological screening may be cost-beneficial if the prevalence of immunity is sufficiently high to offset its cost against the consequent reduction in vaccination needs. This critical population prevalence can be calculated given the cost of vaccination and testing.

Differentiation of primary cytomegalovirus infection from reactivation using the urea denaturation test for measuring antibody avidity.

Cytomegalovirus (CMV) is probably the most common agent of prenatal infection of the newborn, and one of 20 congenitally infected newborns shows serious symptoms. It was therefore considered important to be able to differentiate primary CMV from reactivation in pregnant females. A urea denaturation test was used to distinguish primary from secondary rubella infection in which the urea is included in the wash step of the standard IgG ELISA.

Topological mapping of antigenic sites on the Rift Valley fever virus envelope glycoproteins using monoclonal antibodies.

A panel of 17 monoclonal antibodies (MAbs) to the G1 and G2 envelope glycoproteins of Rift Valley fever (RVF) virus were used to analyze the topography and functional properties of the viral antigenic sites. Four heterogeneous antigenic regions which may be interlinked were identified on the G1 protein and four distinct domains on the G2 protein by competitive binding assays. Comparison of the biological activities and epitope specificities of the MAbs against G1 showed that the antigenic domains I, II, and IV were involved in virus neutralization and haemagglutination at different potencies.

Symptomatic rubella re-infection in early pregnancy and subsequent delivery of an infected but minimally involved infant. A case report.

A case of serologically proven symptomatic rubella re-infection in early pregnancy in a healthy multigravida who had been successfully vaccinated is reported to illustrate that the risk to the fetus is considerably less than with primary infection. The infant was infected, as evidenced by specific IgM in cord blood, but had no stigmata of congenital rubella at birth. Growth retardation was apparent at 6 months and hearing loss, not necessarily due to rubella, was detected at 8 months.

Characterization of a carbon monoxide complex of reduced dopamine beta-hydroxylase. Evidence for inequivalence of the Cu(I) centers.

Ascorbate-reduced dopamine beta-hydroxylase (DBH) is inhibited by CO in a competitive manner with respect to molecular O2. Measurement of the stoichiometry of CO binding indicates 0.50 CO bound per Cu(I), which provides the first evidence that the Cu(I) centers in the reduced enzyme are structurally inequivalent.

Comparison of an enzyme-immunoassay with a radio-immunoassay method for the detection of the hepatitis markers anti-HBs, anti-HBc and HBsAg.

A comparative study was carried out on a radio-immunoassay (RIA) and enzyme-immunoassay (EIA) method for detecting the hepatitis markers anti-HBs, anti-HBc and HBsAg. The results indicated that the RIA and EIA were comparable for the HBsAg marker but that the RIA test was more sensitive for anti-HBs and more specific for anti-HBc. The conclusion was that if the EIA test is used for these markers, the laboratory and clinician must be aware of these limitations.

Infestation of cattle by the brown ear tick, Rhipicephalus appendiculatus, does not affect serological responses to foot-and-mouth disease vaccine.

A comparison of the serological responses of tick-free and tick-infested cattle following inoculation with the Botswana SAT 2 foot-and-mouth disease vaccine indicated that infestation by the brown ear tick, Rhipicephalus appendiculatus, did not affect serological responses to the vaccine. This finding implies that infestation by this tick species is unlikely to influence immunity following routine inoculation against foot-and-mouth disease in tick endemic areas.

A comparison of the effects of controlled-release levodopa (Madopar CR) with conventional levodopa in late Parkinson's disease.

In this multicentre study a controlled-release formulation of levodopa and the decarboxylase inhibitor benserazide (Madopar CR) was evaluated in patients with Parkinson's disease exhibiting dose-related fluctuations in motor performance in response to conventional levodopa preparations. The effect of Madopar CR, with or without conventional levodopa/benserazide, on the proportion of time spent "on", "off" or "intermediate" was compared with that of previous conventional levodopa/decarboxylase inhibitor therapy. Evaluation of the two periods of optimum therapy was based on both patient diary data and investigator opinion.

An open study of interferon in HIV-antibody-positive men.

Alpha-2a-recombinant interferon (Roferon A) was given subcutaneously in a dose of 3 mega units twice weekly for 15-18 months to 14 HIV-antibody-positive, p24-antigen-negative men with minimal HIV-related disease. Interferon was well-tolerated and safe. Although there was either improvement or lack of deterioration initially in 22 out of 26 HIV disease markers, including lymphadenopathy, thrombocytopenic purpura and nail fungal infection, there were 11 instances of HIV disease indicators appearing during the study.

Comparison of an antibody-capture IgM enzyme-linked immunosorbent assay with IgM-indirect immunofluorescence for the diagnosis of acute Sindbis and West Nile infections.

The development and evaluation of an antibody-capture ELISA for the detection of IgM antibodies to Sindbis (SIN) and West Nile (WN) viruses are described. Comparison of the ELISA results with those obtained by indirect immunofluorescence (IIF) antibody tests using both fluorescein and biotinylated anti-human IgM conjugates, showed that the former technique was both more sensitive and specific than the IIF methods. There were no false positives by the ELISA whereas with the IgM-IIF assays a high percentage of false positives were obtained.

Treatment of periscaphoid osteoarthritis by Silastic scaphoid implant.

Periscaphoid osteoarthritis may arise de novo or as a sequel of an established non-union of a scaphoid fracture. The treatment of resultant pain and disability often presents a difficult problem since internal fixation and/or bone grafting of the pseudoarthrosis may fail to relieve the symptoms due to degenerative change. Many methods of alleviating these symptoms have been suggested in the past.

Susceptibility of dogs to West Nile virus: a survey and pathogenicity trial.

A serological survey of dogs from the highveld region of South Africa showed that 37 per cent (138 of 377) had neutralizing antibodies to West Nile (WN) virus and only 2.7 per cent (10 of 377) had antibodies to Sindbis virus. WN virus was isolated from one of the WN-antibody negative sera.

The nighttime problems of Parkinson's disease.

In a national survey conducted among 220 patients with Parkinson's disease (PD), 215 reported experiencing disabilities at night or on waking. The most common problems were inability to turn over or get out of bed and a frequent need to pass urine during the night. For the majority of patients, sleep was disrupted.

Observations on antibody levels associated with active and passive immunity to African horse sickness.

Tests for neutralising (NT) antibodies to the nine serotypes of African horse sickness (AHS) virus on the sera of three groups of horses confirmed that an increasing number of immunisations with vaccine containing attenuated strains of serotypes 1 to 6 of the virus, leads to broader response to the various serotypes and to higher individual titres. Nevertheless some horses failed to respond to one or more serotypes despite receiving numerous immunisations and it was clear that vaccine containing only serotypes 1 to 6 could not be relied upon to induce adequate cross-immunity to serotypes 7 to 9 of the virus. Highest antibody titres and broadest cross-reactivity were recorded in a fourth group of horses which had apparently suffered natural infection recently.

Active site of dopamine beta-hydroxylase. Comparison of enzyme derivatives containing four and eight copper atoms per tetramer using potentiometry and EPR spectroscopy.

Potentiometric titrations, continuous wave EPR, and microwave power saturation measurements have been used to examine 8-Cu and 4-Cu forms of native dopamine beta-hydroxylase and its azide derivative. The formation curve for the binding of Cu2+ to the apoenzyme is best fit by assuming two independent binding sites per subunit, with pK' values of 8.90 and 7.

African horse sickness in Zimbabwe: 1972 to 1981.

During the nine years from October 1972 to September 1981 African horse sickness (AHS) virus was isolated from 23 suspected cases of the disease in Zimbabwe and complement fixation antibody titres indicative of recent infection were detected in a further 49 horses. The 23 isolations belonged to seven of the nine known serotypes of AHS virus. In response to a questionnaire in 1980 the owners of 20% (1,654/8,000) of the horses in Zimbabwe indicated that they had recorded 207 cases of clinically diagnosed AHS with 107 deaths from 1975 to 1980.

Spectral characterization of manganese peroxidase, an extracellular heme enzyme from the lignin-degrading basidiomycete, Phanerochaete chrysosporium.

Manganese peroxidase (MnP) is a component of the lignin degradation system of the basidiomycetous fungus, Phanerochaete chrysosporium. This novel MnII-dependent extracellular enzyme (Mr = 46,000) contains a single protoporphyrin IX prosthetic group and oxidizes phenolic lignin model compounds as well as a variety of other substrates. To elucidate the heme environment of this enzyme, we have studied its electron paramagnetic resonance and resonance Raman spectroscopic properties.

Antigenic analysis of West Nile virus strains using monoclonal antibodies.

Seventeen monoclonal antibodies (MAbs) were prepared against the flavivirus West Nile strain H442. While the majority of these were specific for the major envelope protein, MAbs directed against the NS1 and ns4a nonstructural proteins were also identified. The MAbs were tested by indirect immunofluorescence against 16 southern African West Nile (WN) isolates, representative strains from the two main WN antigenic groups and several viruses from other flavivirus complexes.

Antigenic relationship of West Nile strains by titre ratios calculated from cross-neutralization test results.

The antigenic relationship of ten South African West Nile isolates, the South African prototype virus H442, the Egyptian strain EG101 and the Indian strain G2266 were compared using titre ratios. The titre ratios or 'R' values were calculated from heterologous and homologous neutralization titres and expressed as a percentage. Substantial antigenic differences were demonstrated between the South African prototype strain and the majority of the recently obtained South African isolates, seven of which were fairly closely related and possibly form a distinct antigenic sub-set.

Preparation and use of monoclonal antibodies for identifying Crimean-Congo hemorrhagic fever virus.

Seven monoclonal antibodies were prepared against a South African strain of Crimean-Congo hemorrhagic fever (CCHF) virus and were found to be directed against viral nucleocapsid protein. Five of the monoclonal antibodies reacted to high titer in indirect immunofluorescence (IF) tests and enzyme-linked immunosorbent assays (ELISA) with 22 strains of CCHF virus and failed to cross-react with the closest antigenic relative of CCHF, Hazara virus, or with 4 other nairoviruses which need to be distinguished from CCHF virus in Africa. These antibodies, used in the IF technique, readily detected antigens induced by all strains of CCHF virus included in the study in cell culture monolayers and mouse brain tissue, which represent the systems commonly used for isolation of CCHF virus.

Viscosity of food gums determined in vitro related to their hypoglycemic actions.

Experiments were carried out in vitro and in normal human subjects to evaluate alternative food-grade viscous polysaccharides as agents for reducing postprandial hyperglycemia and to assess the relationship between the in vitro and in vivo performance of the polysaccharides. A 1:1 mixture of xanthan and locust bean gum (X/LBG) had the greatest viscosity at equivalent concentrations and shear rates and was more effective than guar gum, xanthan, or locust-bean gum at inhibiting glucose movement in vitro. It was not, however, more efficient in lowering postprandial blood glucose and plasma insulin in human subjects when incorporated in a drink containing 50 g glucose.

Dengue fever imported from India. A report of 3 cases.

After visiting Saudi Arabia and India a woman became ill within 1 week of her return to Durban. Dengue type 1 virus was isolated from acute-phase serum, and antibody seroconversion was demonstrated. This is the first case of dengue fever in the RSA since the 1926-1927 epidemic.

The status of dengue fever virus in South Africa--serological studies and diagnosis of a case of dengue fever.

To assess the possibility of a dengue epidemic occurring in South Africa 3 groups of survey sera and 2 groups of patients' sera, from a dengue high risk area of South Africa, were tested for antibodies to several flaviviruses. 3.8% (75/1951) of the survey sera and 9.

Sindbis and West Nile virus infections in the Witwatersrand-Pretoria region.

From mid-December 1983 until mid-April 1984, there was an epidemic of Sindbis (SIN) virus infection in the Witwatersrand-Pretoria region in which hundreds of human cases were diagnosed clinically. Twenty-eight of these diagnoses were confirmed in the laboratory by seroconversion as being infections with SIN virus, and 5 cases of infection with West Nile (WN) virus were also found. Attempts to isolate virus from 66 patients, mainly from serum specimens, were unsuccessful.