Biomedical subjects
R K Adair
Publications and source records attributed to R K Adair.
Criticism of Lednev's mechanism for the influence of weak magnetic fields on biological systems.
V. V. Lednev has proposed a mechanism that he suggests would allow very weak magnetic fields, at the cyclotron resonance frequency for Ca2+ ions in the earth's field, to induce biological effects. I show that for four independent reasons no such mechanism can operate.
Marital status and psychiatric disorders among blacks and whites.
This paper examines the association between marital status and psychiatric disorder for Blacks and explores the extent to which these patterns differ from those for Whites. Widowed and separated/divorced Black males and females have higher rates of disorder than the married; never-married Blacks do not have an elevated risk of psychiatric illness. The association between marital status and disorder for White males is similar and stronger than that observed for Blacks. For White women, the separated/divorced have a higher risk of disorder than the married, and unmarried White females have higher rates of the substance abuse disorders, but lower rates of the anxiety disorder than the married. Across all marital status groups, Black males and White males have higher rates of disorder (except for depression), than females. A complex pattern emerges when gender differences in the relative rates of disorder for unmarried Blacks compared to married Blacks are considered. Separated/divorced Black men, widowed Black women, and never-married Black men are worse off than their respective peers. Except for the separated/divorced, opposite patterns are evident for Whites. Directions for further research are outlined.
The protective efficacy of polyvalent pneumococcal polysaccharide vaccine.
BACKGROUND: Although the protective efficacy of pneumococcal polysaccharide vaccine has been demonstrated in randomized trials in young African gold miners, there has been controversy about its efficacy in older Americans at risk for serious pneumococcal infections. To assess the vaccine's protective efficacy against invasive pneumococcal infections, we conducted a hospital-based case-control study of the efficacy of pneumococcal vaccine in adults with a condition recognized to be an indication for receiving the vaccine. METHODS: From 1984 to 1990, adults in whom Streptococcus pneumoniae was isolated from any normally sterile site were identified by prospective surveillance in the microbiology laboratories of 11 large hospitals; those with an indication for pneumococcal vaccine were enrolled as case patients. For each case patient, one control was matched according to age, underlying illness, and site of hospitalization. We contacted all providers of medical care to ascertain each subject's history of immunization with pneumococcal vaccine. Isolates of S. pneumoniae were serotyped by an investigator unaware of the subject's vaccination history. RESULTS: Thirteen percent of the 1,054 case patients and 20 percent of the 1,054 matched controls had received pneumococcal vaccine (P less than 0.001). When vaccine was given in either its 14-valent or its 23-valent form, its aggregate protective efficacy (calculated as a percentage: 1 minus the odds ratio of having been vaccinated times 100) against infections caused by the serotypes represented in the vaccine was 56 percent (95 percent confidence interval, 42 percent to 67 percent; P less than 0.00001) for all 983 patients infected with a serotype represented in the vaccine, 61 percent for a subgroup of 808 immunocompetent patients (95 percent confidence interval, 47 percent to 72 percent; P less than 0.00001), and 21 percent for a subgroup of 175 immunocompromised patients (95 percent confidence interval, -55 percent to 60 percent; P = 0.48). The vaccine was not efficacious against infections caused by serotypes not represented in the vaccine (protective efficacy, -73 percent; 95 percent confidence interval, -263 percent to 18 percent; P = 0.15). CONCLUSIONS: Polyvalent pneumococcal vaccine is efficacious in preventing invasive pneumococcal infections in immunocompetent patients with indications for its administration. This vaccine should be used more widely.
Biological effects on the cellular level of electric field pulses.
Analysis of electric and magnetic fields in the human body generated upon exposure to external pulsed electric fields are used to consider possible biological effects at the cellular level. For peak external field strengths as high as 100 kV m-1, the effects of the consequent internal electric fields on sensitive cell elements, such as the membranes, organelles, and the macromolecules that carry genetic information, are shown to be small compared with the normal thermal agitation of the elements. Hence, based on the description of the cell and the analysis presented here, such pulses cannot be expected to produce any biological effects at the cellular level.