Towards a standardized approach to DNA fingerprinting of Mycobacterium bovis. International Union Against Tuberculosis and Lung Disease, Tuberculosis in Animals Subsection

The Tuberculosis in Animals Subsection of the International Union Against Tuberculosis and Lung Disease (IUATLD) recently identified a need to standardize the deoxyribonucleic acid (DNA) strain typing of Mycobacterium bovis. The standard method for strain typing of M. tuberculosis isolates cannot be directly extrapolated to M. bovis due to the low copy number of IS6110 identified in the majority of M. bovis strains, particularly from cattle. To improve the resolution of M. bovis strains, alternative methods and additional DNA probes have been investigated. In combination with studies of published literature, laboratories performing M. bovis DNA fingerprinting were surveyed. Results of these surveys allowed us to reach consensus and to make recommendations for DNA typing of M. bovis isolates, which hopefully will lead towards a standardized approach to the DNA fingerprinting of this organism. This approach, in conjunction with conventional epidemiological traceback approaches, should facilitate more accurate and effective investigations into the epidemiology, maintenance and transmission of M. bovis within and between man and domesticated, feral and wild animals, both at a local and a global level.     

Lacrimal canaliculitis due to Arachnia (Actinomyces) propionica

The clinical and microbiological findings in a chronic case of lacrimal canaliculitis due to Arachnia propionica are described. Bacterial culture and identification should be performed in the investigation of the disease in order to establish the role of A. propionica and other specific actinomycetes at the acute as well as at the chronic stage.     

Rapid postmortem changes in the cellular localisation of amino acid transmitters in the retina as assessed by immunocytochemistry

We have assessed by means of immunocytochemistry, the cellular distributions of the amino acid transmitters GABA, glycine and glutamate, and the free-radical scavenger taurine, in the retinae of adult rabbits at various times after death. Within 10 min of death, horizontal cells began to display immunoreactivity for GABA, whilst displaced amacrine cells began to display immunoreactivity for glycine. By 40 min postmortem, GABA was present in glial cells. Glutamate, which is not normally detectable in retinal glia, was detected in such glia by 20 min postmortem. By contrast immunocytochemically detectable glycine did not accumulate in glia. There was a gradual diminution of immunoreactivity for taurine in glial cells and photoreceptors. By 2 h postmortem, most immunoreactivity had disappeared from the retina. We conclude that amino acid transmitters show rapid changes in their distributions immediately after death, which may be related to changes in the patterns of transmitter release and uptake, and changes in degradation mechanisms. The rapid changes in cellular localisation of amino acid immunoreactivity illustrated in this study, indicate that the fixation of nervous tissues must be performed rapidly. Moreover, the massive loss of immunoreactivity by 2 h postmortem suggests that any assays for content of these transmitters at this, and subsequent time-points, will bear little resemblance to the values obtained at the time of death.     

Haematological aspects of antenatal diagnosis for thalassaemia in Britain

The results are described of 200 antenatal diagnostic tests for haemoglobinopathies performed on samples of fetal blood obtained during the second trimester of pregnancy. Haemoglobin A synthesis in the fetus was measured by incorporation of tritiated leucine in vitro and separation of the globin chains on CM23 columns. The range of HbA synthesis detected was 3.5-8.0% in normal fetuses, 2.0-5.0% in fetuses with thalassaemia trait, and less than 1.6% in fetuses with thalassaemia major. There were eight cases in which other haemoglobinopathies were diagnosed. 29% of the pregnancies were terminated because thalassaemia major was diagnosed, and 9.5% of the remaining healthy fetuses were lost for obstetric reasons. Follow up has been possible for 96% of the 124 surviving babies and three misdiagnoses have come to light; one false positive (0.5%) and two false negatives (1%). These figures represent a first effort at antenatal diagnosis for haemoglobinopathies and it is likely that they will improve with the passage of time.     

Effect of a specific platelet-activating factor antagonist on cardiovascular and peripheral cellular responses to colonic ischemia and reperfusion in anesthetized ponies

The role of platelet-activating factor in mediating the cardiovascular and peripheral cellular responses to large-colon ischemia and reperfusion, was explored in anesthetized ponies. A specific platelet-activating factor (PAF) antagonist (WEB 2086) was administered to a group of 6 ponies, and another 6 ponies (controls) were given an equivalent volume of saline solution, prior to 1 hour of large-colon torsion. After correction of the torsion, ponies were monitored during the reperfusion period. Significant (P < 0.05) hypotension and metabolic acidosis developed in all ponies after correction of colonic torsion, cardiac index increased initially, but then decreased significantly (P < 0.05) over the study period. Mean times between correction of torsion and onset of cardiac failure and death were not different between groups. Significant (P < 0.05) thrombocytopenia developed during the reperfusion period in control ponies, but not in WEB-treated ponies. Blood leukocyte concentration in control ponies was more variable and significantly (P < 0.05) decreased immediately upon reperfusion, compared with that in WEB-treated ponies. We conclude that although the cardiovascular responses to colonic ischemia and reperfusion are not prevented by use of a specific PAF-antagonist, specific peripheral cellular responses are mediated by PAF.