Unemployment and mortality in Denmark, 1970-80.

Relative mortality in the period 1970-80 was studied among Danish men and women who were unemployed and employed on the day of the 1970 census. The study population consisted of the total labour force in the age range 20-64 on 9 November 1970--that is, about 2 million employed and 22,000 unemployed people. Relative mortality was analysed by a multiplicative hazard regression model (as a natural extension of the standardised mortality ratio) and a multiplicative regression model with extra-Poisson variation. A significantly increased death rate (40-50%) was found among the unemployed after adjusting for occupation, housing category, geographical region, and marital state. Analysis of five main causes of death showed increased mortality from all causes, but especially from suicide or accidents. In areas where the local unemployment rate was comparatively high the relative mortality among the unemployed was lower. The increased mortality among the unemployed was interpreted as a consequence of health related selection as well as increased susceptibility associated with the psychosocial stress of unemployment.     

Transforming growth factor β1 increases the phosphoenolpyruvate carboxykinase mRNA level in cultured rat hepatocytes

Transforming growth factor β1 (TGFβ1) elevated the phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance in primary cultures of rat hepatocytes. Although this increase was not as large as the rise in PEPCK gene expression induced by the cAMP-elevating agents glucagon or isoproterenol, the effect of TGFβ1 was several-fold and concentration-dependent, with ED₅₀ at about 2.5 pM, which is in the same concentration range as the previously found growth-inhibitory effect of TGFβ. The data show that the level of mRNA for PEPCK, an enzyme typically expressed in the liver, can be regulated in the same direction by TGFβ1 and cAMP.     

Inferring a single variable from an assemblage with multiple controls: getting into deep water with cladoceran lake-depth transfer functions

Transfer functions have proved very useful for quantitative reconstruction of past environments. Inferring values of a single parameter based on changes in a community with multiple controls may result in unreliable inferences. To assess this unreliability cladoceran surface sediment assemblages from 53 lakes in Greenland, which have substantial variations in lake depth and fish abundance, both of which shape cladoceran communities, were analysed in this study. Redundancy analysis (RDA) revealed that maximum lake depth and either fish abundance or fish presence/absence exerted substantial and significant control on the cladoceran assemblage. Partial RDA showed that maximum lake depth and fish abundance uniquely explained 7.9 and 5.1%, respectively, with 5.3% variance being shared. A transfer function to infer lake depth from cladoceran sub-fossils was constructed and performed moderately well [coefficient of determination (r ²) = 0.65; root mean square error of prediction (RMSEP) = 0.32 log maximum depth] on the full dataset. When outliers, defined by a bootstrapped prediction error greater than 25% of the total depth gradient, were excluded, the model performed well (r ² = 0.74, RMSEP = 0.25 log maximum depth). The improved transfer function was then applied to sedimentary assemblage from a sediment core from Lake Bores?, in North-eastern Greenland, covering 9,000 years. A large increase in lake depth was inferred around 6250 bp. Whilst the climate was wetter at that time, the inferred changes in depth likely reflect the alteration of the food web, which resulted from the arrival of fish in the lake. This highlights the risks of using single-variable inference models for hindcasting change in lake physical and/or food web structure when there are other important co-variables.     

A cladistic approach to relationships in pentastomida.

The positioning of the Pentastomida among the Metazoa has provoked many debates up to the present. On the other hand, the internal relationships among the pentastomid subgroups have received much less attention in the past. We provide the first phylogenetic analyses under Hennigian principles. Thirty-two morphological characters were selected from the primary literature, analyzed manually, and then with the program Hennig86. Four most parsimonious trees were obtained; these were analyzed by successive weighting and reduced to 1 consensus cladogram 380 steps long, with a consistency index of 0.98 and a retention index of 0.99. Characters were also analyzed as unordered, producing results that were congruent with the previous analyses. The internal groups were ordered according to the following system: (Heymnonsicambria + Haffnericambria + Backlericambria (Cephalobaenida (Railietiellida nov. (Reighardiida nov. (Porocephalida (Linguatuloidea (Linguatulidae + Subtriquetridae) + Porocephaloidea (Sebekidae + Porocephalidae))))))). This phylogenetic system is largely congruent with the first modern taxonomic arrangement proposed for the Pentastomida.     

The proliferative response of rat liver parenchymal cells after partial hepatectomy A methodological study comparing flow cytometry of nuclear DNA content and in vivo and in vitro uptake of thymidine

Abstract. DNA synthesis in rat hepatocytes, from livers regenerating after 70% hepatectomy, was assessed by flow cytometric determination of nuclear DNA content and by incorporation of [³H]thymidine. Parenchymal liver cells were isolated by collagenase perfusion and low-speed centrifugation. Nuclei from the isolated cells were prepared for flow cytometry by a treatment with detergent, pepsin and RNase, and stained with ethidium bromide. Parallel samples of cells were incubated with [³H]thymidine and analysed for rate of incorporation of radioactivity into DNA and for labelling index determination.
The flow cytometric measure of the replicative response, i.e. the presence of cells with S-phase DNA content within the diploid and tetraploid cell populations, was compared with the incorporation of [³H]thymidine. For each of fourteen animals, including two control rats and twelve partially hepatectomized animals killed either before (at 13 hr after hepatectomy), at the onset (16 and 18 hr) or at the peak (24 hr) of regenerating activity, a fairly good correlation was found between the different methods. Satisfactory resolution of the flow cytometric detection of S-phase cells was indicated by a sorting experiment using an Ortho (system 50-H) cell sorter which demonstrated that after [³H]thymidine injection in vivo 88% of the diploid and 84% of the tetraploid S-phase nuclei were labelled, while labelling in the G¹-fractions was only 2 and 7%, respectively.     

Evidence against a requirement for phospholipid methylation in adenylate cyclase activation by hormones. Methyltransferase inhibitors do not impair cyclic AMP accumulation induced by glucagon or beta-adrenergic agents in rat hepatocytes

Several observations made in the fungus Podospora anserina suggest that translational ambiguity may increase, and possibly must increase, at specific stages of the life cycle. Such changes in the properties of the translational apparatus seem to occur as well in the yeast S. cerevisiae and in the alga C. reinhardii. A slight increase of the misreading level would allow readthrough or frameshifting necessary to synthesise regulatory proteins in low amount at key points of cellular differentiation.