Infected mediastinitis secondary to perforation of superior vena cava by a central venous catheter.

We describe the first case of infected mediastinitis associated with central venous catheter insertion. The rare occurrence of this complication may be explained by the fact that it results from central venous catheter-related bloodstream infection and catheter perforation of superior vena cava. The symptoms of this complication (chest pain, dyspnoea) are not specific. Diagnosis should be confirmed by chest x-ray and computerized tomography which show hydromediastinum and pleural effusion. Removal and subsequent culture of the catheter tip will confirm infection. Appropriate antibiotic therapy, guided by sensitivities of the cultured organisms, should be commenced. Any pleural effusion should be drained by thoracocentesis, and the pleural fluid cultured. In case of fever, bacteraemia or shock, a thoracotomy to drain mediastinal and pleural effusions may be considered.

Reflections on hexavalent chromium: health hazards of an industrial heavyweight.

Chromium has been used commercially in the United States for more than 100 years in metal alloys and other compounds, as a pigment, and in the tanning and metal plating industries, and many studies have looked at its effects in terms of occupational health. But, although scientists know that Cr(VI) is a human carcinogen and that it can cause other deleterious health effects including kidney and liver damage, certain questions remain about the metal's effects, such as which routes of exposures are dangerous for humans.

The next target of bioterrorism: your food.

One of the many forms that biological warfare may take is the targeting of major food crops. In a poor country where millions of citizens depend on staple crops such as rice, an act of bioterrorism that destroys the crop would create a famine, resulting not only in malnutrition and starvation but also in reduced immune resistance to a range of common illnesses. To reduce the potential of deliberate introductions of crop pathogens as acts of terrorism, researchers must be able to "fingerprint" pathogens at the molecular level and discriminate between naturally occurring and deliberately introduced outbreaks. Several domestic and international surveillance, tracking, and reporting efforts are under way.

A stable reagent system for screening and identifying red blood cell irregular antibodies: application to commercial antibodies.

OBJECTIVE: Development of a new solid-phase system for screening and identifying irregular red cell antibodies. MATERIALS AND METHODS: Red blood cell membranes were prepared by a semi-automated procedure in which the hemolysate solution was passed through a hollow-fiber system. The membranes were fixed to the solid phase (microtiter plates) by centrifugation and incubated with 8% fat-free milk. Antibodies added to the microtiter plate were detected by anti-human antibodies adsorbed onto yellow latex particles. RESULTS: The system had good sensitivity (titer <1); 97% of anti-D samples were detected. The detection system was stable for 6 months at 4 degrees C. CONCLUSION: This stable-antigen solid-phase system readily detects and identifies red cell antibodies that are important in transfusion.

Immunodominant E2 (gp53) sequences of highly virulent bovine viral diarrhea group II viruses indicate a close resemblance to a subgroup of border disease viruses.

The genes for the E2 envelope protein, which elicits virus-neutralizing antibodies, from members of the newly described group II of bovine viral diarrhea viruses (BVDVs) were cloned and sequenced. These BVDVs included a thrombocytopenic strain from the United States, a fetal bovine serum contaminant, a strain from Western Canada, and two highly virulent strains, causing high mortality rates, from Quebec. The nucleotide and amino acid sequences of these E2s had only a 60-65% homology with group I BVDV E2s but >90% homology with the E2 of a subgroup of sheep border disease viruses. The E2 gene of the NADL strain was expressed and monospecific antibodies were raised in calves and rabbits. The virus-neutralizing titers of these antisera were 15- to 80-fold lower for the heterologous group of BVDVs as compared to those for the homologous BVDVs.

Comparison of the p125 coding region of bovine viral diarrhea viruses.

The p125 (p54/p80) coding region of two cytopathic (CP) strains (Oregon and Singer) and two noncytopathic (NCP) strains (NY-1 and Draper) of bovine viral diarrhea virus (BVDV) were amplified by the polymerase chain reaction, cloned and sequenced. The sequence data confirmed that the two CP strains do not possess any insertion or deletion in their p125 gene as observed in many other CP strains. In the p80, which showed a high amino acid sequence homology among all strains, no amino acid substitution should could be found which distinguished these CP strains from the NCP strains NY-1 and SD-1. Many amino acid substitutions were found in p54 but their individual importance in the CP phenotype is not clear since critical domains of p54 have not yet been experimentally defined. The p54 protein is much less conserved than p80, and sequence homology, as well as dendrogram analysis, permitted us to distinguish two genotypic groups of BVDV (Ia and Ib). The mean homology between strains of these two groups was 77.3/80.4% for the nucleic acid/amino acid sequences while it was 88.0/88.8% and 91.6/93.3% within groups Ia and Ib, respectively. Furthermore, we found that the p125 sequence of our NY-1 strain showed only 92% sequence homology with the partial p80 gene reported for NY-1 but 99.8% homology with another partial sequence of the p125 gene of NY-1 reported elsewhere. These observations underscored the difficulty of maintaining a specific BVDV strain, especially the NCP biotype, in cell cultures.

Identification of a new group of bovine viral diarrhea virus strains associated with severe outbreaks and high mortalities.

New BVDV strains associated with very high mortalities, which killed about 25% of the veal calves in Quebec in 1993, have been isolated. In this study, characterization of the last two-thirds of the 5' untranslated region (5'UTR) of their genome and virus neutralization experiments with polyvalent antisera raised in different animals both demonstrated that these strains formed a distinct group. Despite a difference of about 25% in the 5'UTR sequence with that of the classical strains, these 5'UTRs maintained the same secondary structure albeit with a higher stability. Serological crossreactivity between the classical and new BVDV strains was relatively low and suggest that new strains should also be included to obtain efficient BVDV vaccines. Based upon the distinct characteristics of these new BVDV strains, we propose to divide BVDV into two groups. Group I comprises the classical BVDV isolates including commonly used laboratory and vaccine strains, and group II comprises the newly described BVDV strains and those associated with thrombocytopenia and hemorrhaging.

Ethical, legal, and social issues of the Human Genome Project: what to do with what we know.

Since fiscal year 1991, the U.S. Human Genome Project has spent $170.6 million in federal funds to help isolate genes associated with Huntington's disease, amyotrophic lateral sclerosis, neurofibromatosis types 1 and 2, myotonic dystrophy, and fragile X syndrome and to localize genes that predispose people to breast cancer, colon cancer, hypertension, diabetes, and Alzheimer's disease. Now comes the hard part. Biology's 21st century megaproject starts to look relatively manageable compared to another challenge facing the enterprise: sorting out ethical, legal, and social issues associated with using this information. "The Human Genome Project," wrote Senior Editor Barbara Jasny in the October 1 Science editorial, stretches "the limits of the technology and the limits of our ability to ethically and rationally apply genetic information to our lives."

A comparison of fibronectinolytic activities from several oral bacteria.

Fibronectinolytic activity from two Gram-positive microorganisms (Streptococcus mutans and Bacterionema matruchotii), and from three Gram-negative oral bacteria (Bacteroides intermedius, Bacteroides gingivalis and Haemophilus actinomycetemcomitans) were compared. 125I-labelled human plasma fibronectin (FN) was incubated either either with bacterial extracts or with concentrated culture medium samples and the patterns of FN-degradation products were determined by SDS-PAGE. Results to date have shown that Streptococcus mutans, Bacterionema matruchotii and Haemophilus actinomycetemcomitans were unable to degrade FN. On the other hand the Gram-negative Bacteroides intermedius and Bacteroides gingivalis were shown to contain Fn-degrading activity. The highest activity was found in the bacterial extracts of Bacteroides gingivalis. Inhibition assays demonstrated that fibronectinolytic activity of Bacteroides gingivalis occurred predominantly by cysteine proteinase(s) while that of Bacteroides intermedius by a common action of serine and cysteine proteinases.

Fibronectin-degrading activity in human crevicular fluid, gingival explants culture medium and bacterial plaques.

125I-fibronectin was incubated with extracts having presumably a proteolytic activity. Plaque from children without gingivitis, plaque from adults with chronic periodontitis, human gingival fluid and pooled culture media of human gingival explants were studied. Proteolysis was usually faster with plaque from patients with adult periodontitis than with plaque from children without gingivitis and the inhibition tests showed that several enzymes were implicated in the process. For the culture medium of gingival explants, the electrophoretic profile of the digestion products of fibronectin was different and showed a decreased activity. Nevertheless the gingival fluid gave a very similar degradation to bacterial plaque. The sulcular content was able to assume enzymatic activity capable of destroying fibronectin. These sulcular activities could be important for bacterial colonisation of sulcular surfaces and perhaps also for fibronectin destruction of periodontal tissues.