ABSTRACT
Four groups of C3H mice were studied to determine effects of substances released into blood from burned tissue on platelet counts and megakaryocyte numbers and sizes. Burns were full thickness scald injuries over 20% of body. Groups were: 1) Single, non-burned (controls); 2) Single, burned; 3) Parabiosed non-burned; 4) Parabiosed, one burned in each pair. Platelet counts and megakaryocyte counts and sizing were done at sacrifice. On 2nd postburn day platelet counts of group 4 were significantly lower (P less than 0.0005) than in group 1, but higher than in group 2. On day 5 platelet counts of group 4, returned to normal, then rose above normal. Two to five days postburn, megakaryocyte diameters were significantly larger in groups 2 and 4. Fifty megakaryocytes from each mouse of treatment groups were measured. A blood-borne substance(s) derived from burned tissue appears responsible for waning and waxing of megakaryocyte activity.
Subject(s)
Burns/physiopathology , Hematopoiesis , Megakaryocytes/physiology , Animals , Bone Marrow Cells , Burns/blood , Male , Mice , Parabiosis , Platelet CountABSTRACT
Living organisms exhibit a phototactic response which can be altered by certain environmental toxic chemical species. The analysis of photobehavior can help in elucidating environmental factors that influence photomotility reactions of the organisms. A method has been developed that measures the phototactic response of Artemia nauplii under the influence of mercuric ion (Hg2+) in synthetic seawater. The phototactic response of Artemia nauplii was manifested by movement of the organisms from a darkened half to lighted half of an experimental vessel containing synthetic seawater. The density as a function of time of Artemia nauplii is determined by removing aliquots from both light and dark sides and then plating on agar for counting under the dissecting microscope. Measurements consistently show a significant movement of nauplii to the lighted side within 45 min of the start of the experiments. The present investigation demonstrated that at concentrations as low as 0.010 mg HgCl2/liter there is an enhancement of phototactic effect on Artemia nauplii by mercuric ion as compared with control. The phototactic response of Artema nauplii is altered by mercuric ion in a dose-related manner, but the mechanism of this effect is presently unknown.
Subject(s)
Artemia/physiology , Mercuric Chloride/pharmacology , Animals , Dose-Response Relationship, Drug , Light , Movement , Time FactorsABSTRACT
The carcinogenicity of vinyl chloride and polyvinyl chloride (VC/PVC) is reviewed with specific attention to the gaps in knowledge for risk estimation and epidemiological presentation of the available data. Although experimental studies have demonstrated the carcinogenicity and mutagenicity of VC/PVC in general, the epidemiologic studies available for review do not include an assessment of carcinogenic risk among humans exposed to these chemicals. This conclusion is based on the observation that the majority of cohort studies reviewed lacked sufficient statistical power because of small sample sizes. Further, in epidemiological studies, individuals were not followed over an adequate period of time during which cancer could become clinically manifest.
