Adverse effects of copper, manganese and mercury, alone and in mixtures on the aorta and heart of Spraque-Dawley rats.

Cardiovascular diseases (CVD) are a common global cause of death and are therefore a major health concern. Inhaled or ingested environmental heavy metals contribute to the development of CVD. The aim of this study was to address the limited information available on the effect of relevant dosages of metals in mixtures. Three metals with reported effects on the cardiovascular system (CVS) were identified, and these metals were copper (Cu), manganese (Mn) and mercury (Hg). In Sprague-Dawley rats, the adverse effects of copper (Cu), manganese (Mn) and mercury (Hg), alone and as part of mixtures, on the blood parameters, the aorta and heart were investigated. Forty-eight male Sprague-Dawley rats were randomly divided into eight groups (n = 6): control, Cu, Mn, Hg, Cu + Mn, Cu + Hg, Mn + Hg and Cu, Mn + Hg. The seven experimental groups received the metal mixtures at 100 times the World Health Organisation (WHO) safety limit for drinking water (2 mg/L for Cu, 0.4 mg/L for Mn and 0.06 mg/L for Hg) via oral gavage for 28 days. After 28 days, compared with the control, red blood cell levels were increased for Cu + Hg. All other measured blood parameters were unchanged. Morphological changes in the tunica media were connective tissue deposition and an abundance of collagen type I in the metal exposed aortic tissues. In the cardiac tissue of metal-exposed rats, changes in the cardiomyocyte and myofibrillar arrangement, with an increase in collagen type I and III was observed. Ultrastructurally, the aortic collagen and elastin band arrangement and the cardiac mitochondrial and myofibrillar arrangement and structures were altered in the experimental groups. These changes indicated that exposure to these metals in rats caused minor changes in the blood parameters, however, the changes in tissue and cellular structure indicated an increased risk for the development of CVD.

Human cytomegalovirus infection in infants with prolonged neonatal jaundice.

BACKGROUND: Although human cytomegalovirus (HCMV) infection in infants has been associated with liver disease, the role of HCMV in infants presenting with prolonged neonatal jaundice is unclear as this clinical picture can be caused by a broad spectrum of underlying conditions. OBJECTIVES: This study aimed to determine a possible role for HCMV infection in infants with prolonged cholestatic neonatal jaundice that could facilitate the appropriate use of diagnostic assays and specific treatment in this condition. STUDY DESIGN: HCMV immunohistochemical staining was performed on liver biopsy specimens received for histopathological examination from 85 infants (mean age 3 months) with a clinical history of prolonged neonatal jaundice. HCMV serology was also performed. RESULTS: One infant with a histological diagnosis of HCMV hepatitis was also positive by immunohistochemical staining, while all other tissue specimens were negative for HCMV. HCMV IgG was positive in 92.3% and HCMV IgM in 39.7% of the infants (n=78). CONCLUSIONS: The serological results confirm the ubiquitous nature of HCMV with many primary infections occurring within the first year of life. Despite this, HCMV hepatitis was uncommon in this cohort.

Analysis of trace amounts of carbon dioxide, oxygen and carbon monoxide in nitrogen using dual capillary columns and a pulsed discharge helium ionisation detector.

Gas mixtures of trace amounts of carbon dioxide (CO(2)), dioxygen (O(2)), and carbon monoxide (CO) in dinitrogen (N(2)) were separated and quantified using parallel dual capillary columns and pulsed discharge helium ionisation detection (PDHID). The detection limits (9 x 10(-9) mol mol(-1) for CO(2), 7 x 10(-9) mol mol(-1) for O(2) and 37 x 10(-9) mol mol(-1) for CO) were lower than those reported previously for similar methods. Uncertainties were calculated and results were validated by comparison of the CO and CO(2) results with those obtained using conventional methods. The method was also used to analyse nitrogen, carbon dioxide and carbon monoxide in oxygen.

Plasmid analysis of Neisseria gonorrhoeae isolates and dissemination of tetM genes in southern Africa 1993-1995.

One group (145 isolates) of Neisseria gonorrhoeae was collected from municipal clinics in Bloemfontein in 1994 and a second group (65 isolates) in 1995. Penicillin and tetracycline MICs were determined and plasmid analysis performed to monitor antimicrobial susceptibilities in conjunction with the occurrence of plasmids in these isolates. The prevalence of penicillin resistance caused by beta-lactamase plasmids remained constant at 9% during the study period. Three high-level tetracycline-resistant strains (MICs 16 mg/L), the first to be detected in South Africa, were isolated in 1994. Although there was a reduction in the percentage of isolates harbouring 24.5 MDa conjugative plasmids (from 79% in 1994 to 46% in 1995), this was partially counteracted by an increase in TetM-encoding conjugative plasmids (25.2 MDa) from 2% to 18.5%. The tetM genes of 13 isolates shown to exhibit high-level tetracycline resistance were characterized as the American type. The American-type tetracycline resistance plasmid was demonstrated in 11 isolates. Digestion with Bg/l showed that two isolates harboured tetM-encoding plasmids that differed from the American- and Dutch-type plasmids described previously: one isolate contained a plasmid that produced two fragments of different sizes from those of the American-type plasmid and the second isolate possessed an American/Dutch hybrid plasmid. Auxotyping/serotyping and random amplified polymorphic DNA analysis revealed a predominant tetracycline-resistant family (NR/IA-6, genomic group I) in Bloemfontein. As there is a high incidence of chlamydial infections in southern Africa requiring tetracycline therapy, selective pressures exist in the environment for the maintenance and rapid spread of high-level tetracycline-resistant N. gonorrhoeae. It is possible that tetM genes may have emanated from Botswana and/or Namibia to Bloemfontein. The establishment of high-level tetracycline-resistant N. gonorrhoeae in Bloemfontein was seen to be complex as a related group of strains was identified, plasmid dissemination was evident and two new TetM-encoding plasmids were demonstrated. The appearance of these TetM-encoding plasmids indicates either that the American- and Dutch-type plasmids are continuing to evolve or that tetM genes are being introduced into different families of 24.5 MDa conjugative plasmids.

Immunity to rabies after administration of prophylactic human diploid-cell vaccine.

The immune status to rabies of 14 volunteers was determined using the commercially available Trousse Platelia Rage (Diagnostics Pasteur) enzyme immunoassay test system. Twelve subjects were evaluated before and between 6 months and 60 months after prophylactic intramuscular (deltoid) administration of rabies human diploid-cell vaccine, while the effect of booster doses on a further 2 volunteers was evaluated over an 11-year period. Optical density values were converted to international units to allow correlation with World Health Organisation seroneutralisation references. Values of greater than or equal to 0.5 IU are considered protective. The results showed that most individuals were still immune 2 years after vaccination; there was a tendency for serum antibody levels to decrease over a 5-year post-vaccination period. Antibody levels rose sharply after booster immunisation, after which they decreased at a much slower rate. In general, results revealed that after the first booster, additional booster vaccinations at 5-yearly intervals would provide adequate prophylactic immunity. There was, however, much individual variation, which emphasises the need to evaluate each individual at regular and shorter intervals to determine the need for booster vaccine doses. The test method employed is economical and well suited to such evaluations.

Frail aged persons residing in South African homes for the aged who require hospitalisation. Part I. Urban areas.

The numbers and characteristics of white residents identified by medical and nursing staff as requiring more staff time and/or expertise and/or medical equipment than is available in homes for the aged were assessed. Only 27 out of 2,447 (1.1%) extremely infirm aged persons resident in 93 homes for the aged would, in the opinion of institutional staff, benefit by admission to a long-term care hospital catering for chronically ill. The conditions affecting these residents are described and recommendations relating to their management made.

Frail aged persons residing in South African homes for the aged who require hospitalisation. Part II. Rural areas.

The numbers and characteristics of white residents identified by medical and nursing staff to require more staff time and/or expertise and/or medical equipment than was available in rural homes for the aged in the Orange Free State were assessed. In the opinion of institution staff, 12.6% of extremely infirm aged persons would benefit by admission to a hospital catering for the chronically ill. The conditions affecting these residents are described and recommendations relating to their management are made.