Perceived control in relation to socioeconomic and behavioral resources for health.

Perceived control is a personality characteristic that contributes to well-being, but few studies have attempted to integrate the functions of perceived control with those of other determinants of health. This research tested two hypotheses about the functions of perceived control: (a) individual differences in perceived control would account for socioeconomic differences in self-rated health status; (b) performance of health-related behaviors would account for the health benefits of perceived control. Using data from adult, nonproxy respondents in the National Population Health Survey of Canada (1995; n = 11, 110), confirmatory factor analysis supported a measurement model of self-rated health status composed of two correlated factors: physical health (i.e., chronic conditions. restricted activities, self-rated general health, physical functional capacity) and mental health (i.e., distress, depression). Structural equation modeling supported the first hypothesis, but not the second, regarding perceived control as a determinant of self-rated physical and mental health. Health-related behaviors partially mediated age differences in self-rated health, but different behaviors functioned in this way for men than for women. The findings suggest that psychological process, that of perceiving control over life events, underlies social inequality in health. Health-related behaviors appear not to serve as the primary mechanism through which perceived control influences health.

Primary diffuse leptomeningeal gliomatosis predominantly affecting the spinal cord: case report and review of the literature.

Primary leptomeningeal gliomatosis is a rare, fatal neoplastic syndrome. A 71 year old man is reported on, who after a 2 month history of back stiffness, epigastric pain, and weight loss developed visual blurring. Cranial CT and MRI studies showed no leptomeningeal enhancement. Examination of CSF 10 weeks premortem showed an increase in protein and decrease in glucose but no malignant cells. He became increasingly confused and repeated CSF examination showed inflammation and a few suspicious cells but no definitive evidence of neoplasia. He died 7 months after onset of his initial symptoms. At postmortem meningeal whitening was seen at the base of the brain and over the spinal cord. Histology disclosed diffuse leptomeningeal gliomatosis (GFAP positive, cytokeratin negative) over the brain, optic nerves, and spinal cord without parenchymal involvement. No tumour was found in internal organs. The diagnosis of primary leptomeningeal gliomatosis was not evident after cranial CT and MRI and CSF examination premortem. Suspected cases need MRI scanning of the entire neuraxis and meningeal biopsy.

Mutagenesis at the ouabain-resistance locus of 3.7.2C L5178Y cells by chromosomal mutagens.

Chemical mutagens including methyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, iodomethane, and epichlorohydrin have been classified as "chromosomal mutagens" in the L5178Y/thymidine kinase (TK) gene mutation assay by Clive and coworkers [Mutat Res 59:61-108, 1979; and "The Predictive Value of Short-Term Screening Tests in Carcinogenicity Evaluation." Amsterdam: Elsevier/North Holland, pp 103-123, 1980] who observed mutagen-dependent increases in small TK-deficient mutant colonies with detectable damage to the chromosome (11) that carries the TK locus. In this study, we tested these four chemicals for the induction of gene mutations at the ouabain-resistance (ouares) locus of 3.7.2C L5178Y cells to determine if presumptive chromosomal mutagens would go undetected at a gene locus that is unresponsive to chromosomal damage. A final concentration of 375 micrograms/ml ouabain in soft-agar medium selected against the ouabain-sensitive phenotype without loss of the mutagen-induced ouabain-resistant phenotype. Verification of the mutant phenotype was completed for six individual soft-agar ouares colonies derived from mutagen-treated cultures via growth for 10-11 days in nonselective medium followed by retesting for colony formation in selective soft-agar medium. Dose-related reproducible increases in the frequency of ouabain-resistant mutants were observed for 3.7.2C L5178Y cells that had been exposed for 3 hr to 24-46 micrograms/ml epichlorohydrin, 1.9-3.6 micrograms/ml iodomethane, 0.006-0.011 micrograms/ml N-methyl-N'-nitro-N-nitrosoguanidine and and 2.0-5.4 micrograms/ml methyl methanesulfonate. Also, treatments with EMS, which induced sufficient numbers of ouares colonies to permit analysis of colony size distribution, showed the existence of a bimodal size distribution similar to those reported for TK-deficient mutants. This discovery suggests that mutant colony size in this cell line may be independent of specific gene locus effects. We conclude that (1) chemicals that induce a high proportion of chromosomal mutants, as detected at the TK locus in earlier studies, also induce single gene mutations at the ouabain-resistance locus and (2) a bimodal distribution of mutant colony sizes in soft-agar medium after short expression periods may be a distinctive characteristic of the 3.7.2C L5178Y cell line and is not confined to the TK locus.