Prospective cohort study of predictors of incident low back pain in nurses.

OBJECTIVE: To assess the impact of handling patients and indicators of individual susceptibility on risk of low back pain in nurses. DESIGN: Prospective cohort study with follow up by repeated self administered every three months over two years. SETTING: NHS university hospital trust. SUBJECTS: 961 female nurses who had been free from low back pain for at least one month at the time of completing a baseline questionnaire. MAIN OUTCOME MEASURES: Incidence of new low back pain during follow up and of pain leading to absence from work. RESULTS: Of 838 women who provided data suitable for analysis, 322 (38%) developed low back pain during follow up (mean 18.6 months), including 93 (11%) whose pain led to absence from work. The strongest predictor of new low back pain was earlier history of the symptom, and risk was particularly high if previous pain had lasted for over a month in total and had occurred within the 12 months before entry to the study (incidence during follow up 66%). Frequent low mood at baseline was strongly associated with subsequent absence from work for back pain (odds ratio 3.4; 95% confidence interval 1.4 to 8.2). After adjustment for earlier history of back pain and other potential confounders, risk was higher in nurses who reported frequent manual transfer of patients between bed and chair, manual repositioning of patients on the bed, and lifting patients in or out of the bath with a hoist. CONCLUSIONS: Of the indicators of individual susceptibility that were examined, only history of back trouble was sufficiently predictive to justify selective exclusion of some applicants for nursing posts. The main route to prevention of back disorders among nurses is likely to lie in improved ergonomics.     

The social-psychological precursors to cancer

This article attempts to review the research literature relating the possible psychosocial precursors to cancer. It explores the evidence linking personality predispositions and adverse life events to cancer, providing an indication of where future research should be pursued.     

Synthesis and bioassay of isoprenoid 3-alkylthio-1,1,1-trifluoro-2-propanones: Potent,selective inhibitors of juvenile hormone esterase

Four 3-alkylthio-1,1,1-trifluoro-2-propanones with juvenile hormone-like side chains were prepared from citronellol and homogeraniol. These substrates were designed as possible transition-state analogs for the juvenile hormone (JH)-specific esterases present in insects. These four isoprenoid trifluoromethyl ketones were assayed in vitro with JH esterase and general esterases from larvae of the cabbage looper, Trichoplusia ni (Lepidoptera, Noctuidae), and with eel acetylcholinesterase and bovine chymotrypsin. JH esterase inhibition I₅₀ values were in the nanomolar range for all four compounds, while the other esterases had I₅₀'S which were 10³ to 10⁵ higher. The high selectivity of these inhibitors is believed to be due to their similarity in size and functionality to natural JH III. Treatment of T. ni larvae in vivo with solutions of the most active analog, 3-[(E)-4,8-dimethyl-3,7-nonadienylthio]-1,1,1-trifluoro-2-propanone (DNTFP) causes a dose-dependent delay in pupation and a concurrent selective inhibition of JH esterase. These data support the hypothesis that the reduction in in vivo JH titer in larval T. ni is due, in part, to hydrolysis of the hormone by selective esterases. DNTFP appears to be competing with JH for the active site of JH esterase.     

Characteristics of a human epidermal squamous carcinoma cell line at different extracellular calcium concentratrions

A continuous line derived from a human skin squamous cell carcinoma has been grown in media of high, normal and low Ca²⁺ concentrations. The growth rate was unaffected by the Ca²⁺ levels even though morphological changes were observed. Desmosomes were absent at low Ca²⁺ and areas of cell piling were observed at high Ca²⁺. Cell protein staining patterns on polyacrylamide gels were identical for cells grown at the three Ca²⁺ levels. The variations were minor for the glycoproteins reacted with ¹²⁵I-conA. Lactoper-oxidase iodination revealed changes in cell surface proteins, most markedly in the emergence of new proteins at high Ca²⁺.     

Hormonal and compartmental correlates during adrenarche in the chimpanzee

Ten male and eleven female Chimpanzees from three to nine years of age were studied to establish possible correlations between behavioral changes and hormonal changes peculiar to adrenarche and the pre-puberty period. Most of the thirteen behaviors studied varied with age, body weight and hormones. For the males, the correlations were significant statistically for age, weight and plasma concentration of testosterone and of FSH. The correlations for the females were more often not significant statistically. In ten out of the thirteen behaviors for the female, however, the correlations with the sulfate of plasma dehydroepiandrosterone were in the same direction as those observed for the males with testosterone.     

Similar effects of platelet-derived growth factor and epidermal growth factor on the phosphorylation of tyrosine in cellular proteins

Platelet-derived growth factor (PDGF) stimulates the phosphorylation of proteins at tyrosine when added to quiescent 3T3 cells, as evidenced by the increase in the amount of phosphotyrosine, relative to phosphoserine and phosphothreonine, in cellular proteins. The increase was detected within 1 min of adding PDGF and was maximal by 5 min. This effect showed the same dependence on PDGF concentration as did association of 125I-PDGF with the cells. In different 3T3 cell lines the magnitude of the increase was approximately proportional to the number of PDGF receptors per cell. A number of proteins phosphorylated at tyrosine in response to PDGF have been detected by two-dimensional gel electrophoresis. They include a pair of related 45 kilodalton phosphoproteins, a pair of related 43 kilodalton phosphoproteins and a 42 kilodalton phosphoprotein. Similar changes were noted when quiescent 3T3 cells were incubated with epidermal growth factor. Possibly, these phosphoproteins are primary substrates of the tyrosine protein kinases activated by the receptors for PDGF and epidermal growth factor, and are involved in physiological effects common to the two growth factors.     

Genetics of Ia-like alloantigens in chickens and linkage with B major histocompatibility complex

Two sets of backcross matings were performed to test for linkage between genes coding for the Ia-like antigens ("Ia") and the B erythrocyte antigens (Ea-B) of the chicken. Evidence is presented which indicates that the "Ia" antigens are determined by a single codominant locus and that the Ea-B and "Ia" loci are on the same chromosome. Failure to detect a single recombinant between the Ea-B and "Ia" loci out of 208 progeny suggests close linkage of the two genes with a map distance of up to about 2 centimorgans. The "Ia" genes are thus included in the B major histocompatibility complex of the chicken.     

Somatic Expression and Autosomal Inheritance of Phosphoglycerate Kinase B in Kangaroos

The PGK-B isozyme, currently known as PGK-2 in the mouse nomenclature, is the predominant PGK isozyme in mammalian sperm. In many species it is detectable only in sperm, in spermatogenic testes and in epididymides containing sperm. In this paper, we provide evidence that some kangaroo species express low PGK-B activity in somatic tissues, in addition to high activity in testes. Three kangaroo species, M. rufogriseus, M. robustus and M. giganteus, exhibit polymorphism of PGK-B. Breeding data support the hypothesis of autosomal co-dominant inheritance, as is the case in mice. Population data for the three polymorphisms are discussed. PGK-B is not detectable in somatic tissues or spermatogenic testis extracts of monotreme mammals, birds or lizards; it is probably restricted to therian mammals.