Localized pleural plaques and lung cancer.

In a mass chest radiography survey conducted in 1971 for 7,986 residents of three Finnish communities, 604 subjects (7.6%) with pleural plaques but not other asbestos-related radiographic signs were identified. The same number of referents, each individually matched to each plaque carrier on sex, birth year, and community, was selected from among persons in the same source population with no pleural plaques. The two groups were followed for investigation of incidence of lung cancer during 1972-1989. Twenty-eight of those with plaques and 25 referents contracted lung cancer (crude conditional RR = 1.1; CL95 = 0.7, 1.9). The application of the proportional hazards model, with adjustment for sex, age, and residence, resulted in a hazard ratio of 1.1 (CL = 0.6, 1.8). The risk ratio estimate may be biased; hence, the result is inconclusive in regard to the predictive assessment of lung cancer risk among carriers of pleural plaques.     

Office employment, work with video display terminals, and course of pregnancy. Reference mothers' experience from a Finnish case-referent study of birth defects

In an examination of the possible harmful effects of work in an office environment and the use of a video display terminal (VDT) on the course of pregnancy, the experience of 1,475 reference mothers from a Finnish case-referent study of birth defects was analyzed. The study was based on the national Register of Congenital Malformations, whose data were supplemented with special interviews on mothers' work conditions. The group which worked in an office environment consisted of 239 women, of whom 60 had worked with video display terminals; 805 mothers had not worked in an office. Only mothers who had worked during most of their pregnancy and who had a singleton birth were included; hence 431 women were excluded from the analysis. The information on threatened abortion, length of gestation, birthweight, placental weight, and maternal blood pressure was analyzed. Office work involved no elevated risk of threatened abortion when compared with nonoffice work, and among the VDT users the proportion with symptoms related to an impending early termination of pregnancy was similar to that of other office workers. No unfavorable effects on the length of gestation were observed between the compared groups, and there were no differences in the birthweight of the babies when adjustment was made for gestational age or the other aspects under consideration. Thus the results did not suggest that office employment or work with video display terminals would be harmful for pregnancy.     

Intracerebroventricular immunization with TRH-antiserum lowers blood pressure in spontaneously hypertensive rats.

Centrally administered thyrotropin-releasing hormone exerts a well documented hypertensive effect. In this study, the possible physiological role of thyrotropin-releasing hormone in the central cardiovascular regulation was evaluated in spontaneously hypertensive rats receiving long-term (8-14 days) intracerebroventricular infusion of a heterologous antiserum to thyrotropin-releasing hormone. The effect of this passive immunization on the blood pressure was monitored from conscious animals by the tail-cuff method. Thyrotropin-releasing hormone antiserum significantly decreased the systolic arterial pressure in adult rats with established hypertension. No alterations in serum thyroid hormone status were observed indicating that the antihypertensive effect of immunological blockade of thyrotropin-releasing hormone was not due to changes in the serum thyroid hormone levels. These results provide evidence for a role of endogenous brain thyrotropin-releasing hormone in the maintenance of hypertension in spontaneously hypertensive rats.     

Antigenic properties of Chlamydia trachomatis lipopolysaccharide.

The antigenic properties of the lipopolysaccharide (LPS) of Chlamydia trachomatis L2 were investigated. By means of passive hemolysis, passive hemolysis inhibition, and absorption experiments, it was shown that antiserum raised against chlamydial elementary bodies contained at least two different antibody specificities which reacted with different antigenic determinants of chlamydial LPS. One of these antibodies cross-reacted with enterobacterial Re LPS, recognizing a structure which is shared by both LPSs, whereas the reactivity of the second antibody was restricted to chlamydial LPS. The former antibody could be absorbed with Salmonella minnesota Re LPS, whereas the latter was not affected by this absorption. Therefore, chlamydial LPS possesses two distinct antigenic determinants, one of which is C. trachomatis specific, the other of which is responsible for the cross-reactivity with enterobacterial Re-type LPS. Both antigenic determinants were destroyed during mild acid-catalyzed hydrolysis. It was further shown that free chlamydial lipid A exhibits antigenicity that cross-reacts with free enterobacterial lipid A. This antigenicity, however, as in enterobacterial LPS, is present in a cryptic form, i.e., it is unmasked only after acid hydrolysis of LPS.     

Sleep-wake rhythm in an irregular shift system

Sleep in shift work has been studied extensively in regular shift systems but to a lesser degree in irregular shifts. Our main aim was to examine the sleep-wake rhythm in shift combinations ending with the night or the morning shift in two irregular shift systems. Three weeks' sleep/work shift diary data, collected from 126 randomly selected train drivers and 104 traffic controllers, were used in statistical analyses including a linear mixed model and a generalized linear model for repeated measurements. The results showed that the sleep-wake rhythm was significantly affected by the shift combinations. The main sleep period before the first night shift shortened by about 2 h when the morning shift immediately preceded the night shift as compared with the combination containing at least 36 h of free time before the night shift (reference combination). The main sleep period before the night shift was most curtailed between two night shifts, on average by 2.9 and 3.5 h among the drivers and the controllers, respectively, as compared with the reference combination. Afternoon napping increased when the morning or the day shift immediately preceded the night shift, the odds being 4.35-4.84 in comparison with the reference combination. The main sleep period before the morning shift became 0.5 h shorter when the evening shift preceded the morning shift in comparison with the sleep period after a free day. The risk for dozing off during the shift was associated only with the shift length, increasing by 17 and 35% for each working hour in the morning and the night shift, respectively. The results demonstrate advantageous and disadvantageous shift combinations in relation to sleep and make it possible to improve the ergonomy of irregular shift systems.     

Expression of human pim family genes is selectively up-regulated by cytokines promoting T helper type 1, but not T helper type 2, cell differentiation

Cytokines are the most important inducers of T helper (Th) cell differentiation. Interleukin-12 (IL-12) and interferon-alpha (IFN-alpha) are responsible for human Th1-cell differentiation, while IL-4 is the critical cytokine promoting Th2-cell development. These two subsets of cells co-ordinate immunological responses to pathogens as well as autoimmune or allergic reactions. The pim family of proto-oncogenes encodes serine/threonine-specific kinases involved in cytokine-mediated signalling pathways in haematopoietic cells. Here we demonstrate that expression of pim-1 and pim-2 mRNAs is selectively up- or down-regulated in human cord-blood-derived CD4+ cells freshly induced to polarize towards Th1 or Th2 cells, respectively, whereas their expression is inhibited in both cell types by the immunosuppressive transforming growth factor beta (TGF-beta). Moreover, the Th1-specific cytokines IL-12 and IFN-alpha, but not the Th2-specific cytokine IL-4, transiently up-regulate pim-1 and pim-2 mRNA expression in human peripheral blood T cells and natural killer cells. In addition, the Pim-1 protein levels are strongly up-regulated by Th1-specific cytokines in all of these cell types. Taken together, our results suggest that pim genes and their protein products are involved in the early differentiation process of T helper cells.     

Arterial hypertension associated with the use of a tourniquet with either general or regional anaesthesia

A hypertensive patient with left cardiac enlargement developed marked hypertension under general anaesthesia, during which time a tourniquet was applied around his thigh. When the tourniquet was released, severe hypotension ensued which responded to therapy. The patient, however, died 16 h later of a myocardial infarction. Because of this incident, the anaesthetic and haemodynamic data of 699 patients who underwent limb surgery with a pneumatic tourniquet inflated for at least an hour were retrospectively examined using multivariate analysis. A 30% increase in systolic and/or diastolic arterial blood pressure occurred in 27% of the total patient material and in 67% of those who had had a general anaesthetic. There was a higher frequency of the occurrence of "tourniquet hypertension" with older age, longer operations and the operation site being the lower rather than the upper limb. Tourniquet hypertension rarely occurred in patients with spinal anaesthesia (2.7%) and brachial plexus blockade (2.5%), while those with intravenous regional anesthesia had a higher incidence (19%) of hypertension.     

Malaria prophylaxis and self-therapy in airline crews

The risk of malaria infection in airline crews is estimated to be 0.5 per 1,000 persons per night in areas with high levels of malaria transmission. Routine chemoprophylaxis for years is not recommended because of possible side effects. Airline crews should therefore use appropriate measures to prevent mosquito bites. In addition, they may need to carry "standby" medication with them to be used for presumptive treatment of a febrile illness if medical attention is not readily available.