Adult body size and survivorship in a field population of Aedes triseriatus

Aedes triseriatus pupae, host-seeking, and ovipositing females were collected at a southern Wisconsin site endemic for La Crosse encephalitis virus. The host-seeking and ovipositing females were age-graded by the Detinova and Polovodova techniques, respectively. Wing lengths were determined for all mosquitoes. Wing lengths of the mosquitoes collected as pupae were predicted from pupal weight by a simple regression equation. There was significant seasonal variation in body size of adult females, but no strong evidence that increased size was advantageous to survival. It is concluded therefore that the potential length of infective life is not affected by the size of the adult female.     

Increasing evidence of the rise of cancer in workers exposed to vinylchloride.

The results of a cancer mortality study among workers employed in the production of vinylchloride and polyvinylchloride between 1939 and 1977 suggest a significant increase in deaths from malignancies of the lymphatic and haemopoietic tissues. Mortality for tumours of the digestive organs, respiratory system, bone and connective tissues, brain, and skin are also greater than in the general population. There were no registered cases of liver angiosarcoma in the study cohort during the follow up period. The risk of cancer was highest among the workers exposed to concentrations of VC of 300 mg/m3 and more who had worked at the plant for 15 to 19 years. The relatively high number of leukaemias and lymphomas in the study group and the absence of liver angiosarcomas probably reflects specific carcinogenic action of different doses of vinylchloride.     

Optimal Selection of Sib Pairs from Random Samples for Linkage Analysis of a QTL Using the EDAC Test

Percentages of extremely concordant and extremely discordant sib pairs are calculated that maximize the power to detect a quantitative trait locus (QTL) under a variety of circumstances using the EDAC test. We assume a large fixed number of randomly sampled sib pairs, such as one would hope to find in the large twin registries, and limited resources to genotype a certain number of selected sib pairs. Our aim is to investigate whether optimal selection can be achieved when prior knowledge concerning the QTL gene action, QTL allele frequency, QTL effect size, and background (residual) sib correlation is limited or absent. To this end we calculate the best selection percentages for a large number of models, which differ in QTL gene action allele frequency, background correlation, and QTL effect size. By averaging these percentages over gene action, over allele frequency, over gene action, and over allele frequencies, we arrive at general recommendations concerning selection percentages. The soundness of these recommendations is subsequently in a number of test cases.     

The use of perfluorinated emulsion for prolongation of the endurance period in lethal hypoxia

The apnea model with venovenous perfusion and blood oxygenation in a membrane oxygenator was used to study the gas transport characteristics of perfluorinated emulsion with the aim to prolong the endurance period in lethal hypoxia. The use of PFOS emulsion (40 ml/kg) as a hemodilution agent at relatively low rate of assisted perfusion (35 ml/kg×min) produced no improvement of oxygen supply during the critical period in comparison with conventional plasma substitutes. However, perfusion with oxygenated perfluorinated emulsion prolonged survival as compared with polyglucin perfusion, mainly due to the maintenance of the vitally important organs (heart and brain) and due to the improvement of microcirculation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 10, pp. 477–480, October, 1997     

Electron microscopy of developing calvaria reveals images that suggest that osteoclasts engulf and destroy osteocytes during bone resorption

Summary It is generally accepted that osteoclasts are responsible for the breakdown and removal of bone matrix constituents. However, very little is known about the fate of osteocytes during bone resorption. In the present study we have examined sites of bone destruction in calvaria of young rats aged 4–9 days in the hope of obtaining information on the fate of osteocytes. Decalcified glutaraldehyde-formaldehyde-fixed specimens were prepared for ultrathin section electron microscopy. When sequentially arranged, the images obtained suggest that osteoclasts engulf and destroy osteocytes during bone degradation. We propose that the following sequence of events takes place when a lacuna is opened up by an osteoclast: (1) When the osteoclast comes in contact with an osteocyte, the villi of the ruffled border become flat and broad. (2) Long osteoclastic extensions surround the osteocyte. (3) The osteocyte is subsequently internalized with apparent degradation.