Airborne infection with Mycobacterium leprae in mice.

Although the portal of entry and mode of spread of M. leprae in human leprosy are still uncertain, it is widely held that direct person-to-person skin contact is important. This assumption has ignored the fact that patients with highly bacilliferous leprosy have nasal as well as dermal infection and that, since M. leprae is shed predominantly from the nose, leprosy might be an airborne infection. The present study was designed to investigate this possibility with mice exposed to airborne infection with M. leprae. The conditions are described in which thymectomised-irradiated CBA strain mice exposed to M. leprae aerosols sustained an immediate lung retention of 1 X 10(5) bacteria. Fourteen to 24 months later, 33% (10 of 30) of the mice had countable numbers of acid-fast bacilli (greater than 2 X 10(4)) with the characteristics of M. leprae in one or more homogenates prepared from ears, foot pads, nose or lungs. Evidence is presented from the distribution of M. leprae that the infection had arisen from systemic spresd of bacilli initially entering the lungs rather than from multiplication of organisms locally retained there, or in the nose, at the time of airborne infection. The relevance of these results to the possible route of infection of leprosy in man is discussed.     

Ruthenium nitrosyl complexes: Toxicity toEscherichia coli and yeasts and uptake by marine bacteria

The toxicity and possible accumulation of ruthenium nitrosyl complexes by marine bacteria and test organisms have been studied, A range of these complexes show no toxic effects towardsEscherichia coli K12 at concentrations of mM and below. Yeasts are more sensitive, showing effects on growth at 10 M. The ruthenium nitrosyl complexes tested are unable to permeate the cytoplasmic membrane ofE. coli. This may account for their lack of toxicity. However, these compounds did not have significant inhibitory effects on Mg²⁺-ATPase activity in cell-extracts, I₅₀ values lying in the range 2 to 125 mol(mg protein)^–1. Marine bacteria are capable of taking up ruthenium complexes from simulated effluent, but this cannot be demonstrated in the presence of sediment which competes effectively for binding of complexes. There is minimal likelihood of concentration of ruthenium compounds from effluents by marine bacteria.     

Increased body:brain weight ratio in developing rats after low exposure to organic lead

Tetramethyl lead in an oily vehicle was administered to rats at weekly intervals during gestation and early postnatal life, raising the total lead concentration in the brain to about 1 microgram/g. Birth weight was unaffected, but postnatal body growth was stimulated more than brain growth, resulting in a higher body:brain weight ratio. Histological measures of brain myelination, dendritic growth, granule cell production, and retinal receptor development showed no deficit. We conclude that the body:brain weight ratio is the most sensitive of the parameters measured for detecting the effect on development of exposure to a low concentration of tetramethyl lead. The latter is neurotoxic at higher concentrations, and the stimulating effect on body growth of a low concentration is an example of "hormesis," a phenomenon which has been noted with other toxins.     

Association between Fruit and Vegetable Intakes and Mental Health in the Australian Diabetes Obesity and Lifestyle Cohort

Increasing prevalence of mental health disorders within the Australian population is a serious public health issue. Adequate intake of fruits and vegetables (FV), dietary fibre (DF) and resistant starch (RS) is associated with better mental and physical health. Few longitudinal studies exist exploring the temporal relationship. Using a validated food frequency questionnaire, we examined baseline FV intakes of 5845 Australian adults from the AusDiab study and estimated food group-derived DF and RS using data from the literature. Perceived mental health was assessed at baseline and 5 year follow up using SF-36 mental component summary scores (MCS). We conducted baseline cross-sectional analysis and prospective analysis of baseline dietary intake with perceived mental health at 5 years. Higher baseline FV and FV-derived DF and RS intakes were associated with better 5 year MCS (p < 0.001). A higher FV intake (754 g/d vs. 251 g/d, Q4 vs. Q1) at baseline had 41% lower odds (OR = 0.59: 95% CI 0.46–0.75) of MCS below population average (<47) at 5 year follow up. Findings were similar for FV-derived DF and RS. An inverse association was observed with discretionary food-derived DF and RS. This demonstrates the association between higher intakes of FV and FV-derived DF and RS with better 5 year mental health outcomes. Further RCTs are necessary to understand mechanisms that underlie this association including elucidation of causal effects.     

What is the Level of Evidence Substantiating Commercial Payers’ Coverage Policies for Total Joint Arthroplasty?

BackgroundThe prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.MethodsThe references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.Results282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.ConclusionMost of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.     

Demand for health care information prompts media-institution alliances

The growing demand for health care information has prompted at least one health care system to form a partnership with its local television station and a health care news provider. Allina Health System, Minneapolis, KSTP-TV and 20-year-old Medatar team up to create a local version of Health Matters for Allina's market area. Medstar serves clients in more than 130 American cities.     

Antigen presenting cell function in HIV-1 infected patients

Antigen presenting cell (APC) function is central to the activation of anti-viral cytotoxic T-cells and antibody production. In previous studies we have evaluated APC function in HIV-1 infected patients as the capacity to present peptide to a well defined panel of CD4 T-cell clones. We found that APC from HIV-1 infected patients were defective in the capacity to present peptide to CD4 T-cell clones. The APC defect uncovered by this method was present early in infection and worsened with increasing viral load, suggesting that it was an important determinant of progression and anti-viral efficacy. The CD4 T-cell clones were, however, found to vary in their susceptibility to the APC defect. CD4 T-cell clones that failed to respond to peptide presented by HIV + APC were 1000-fold more readily inhibited by anti-CD4 antibody than T-cell clones which consistently responded to APC from patients infected with HIV-1 (HIV + APC). An intermediate group of T-cell clones were also identified that only responded to peptide and HIV + APC from asymptomatic patients. These results suggested that the underlying mechanism for the APC defect was binding of T-cell CD4 by APC-associated gp120. In this paper we discuss the evidence to support this hypothesis.