Hypothyroidism in rats decreases mitochondrial inner membrane cation permeability

We investigated the cation permeability of liver mitochondria isolated from hypothyroid or euthyroid rats by measuring the rate of swelling of respiring mitochondria in acetate salts as a function of membrane potential. Mitochondria from hypothyroid rats have a decreased permeability of roughly 3-fold in the presence of monovalent cations K and tetramethylammonium at any (measured) membrane potential. Since the monovalent cation leak and the proton leak are known to respond similarly to membrane potential our results support the theory that the difference in non-phosphorylating respiration rate between mitochondria from hypothyroid and euthyroid rats is due to a difference in proton leak.     

Thyroid-hormone control of state-3 respiration in isolated rat liver mitochondria.

Oxidative phosphorylation can be treated as two groups of reactions; those that generate protonmotive force (dicarboxylate carrier, succinate dehydrogenase and the respiratory chain) and those that consume protonmotive force (adenine nucleotide and phosphate carriers. ATP synthase and proton leak). Mitochondria from hypothyroid rats have lower rates of respiration in the presence of ADP (state 3) than euthyroid controls. We show that the kinetics of the protonmotive-force generators are unchanged in mitochondria from hypothyroid animals, but the kinetics of the protonmotive-force consumers are altered, supporting proposals that the important effects of thyroid hormone on state 3 are on the ATP synthase or the adenine nucleotide translocator.     

Surface areas,lengths and volumes of Picea abies (L.) Karst. needles: determination,biological variability and effect of environmental factors

Summary A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm²) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm³) by needle volume = 0.208 x projected needle area ^1.353 (r = 0.969).     

Randomised trial of prophylactic daily aspirin in British male doctors

A six year randomised trial was conducted among 5139 apparently healthy male doctors to see whether 500 mg aspirin daily would reduce the incidence of and mortality from stroke, myocardial infarction, or other vascular conditions. Though total mortality was 10% lower in the treated than control group, this difference was not statistically significant and chiefly involved diseases other than stroke or myocardial infarction. Likewise, there was no significant difference in the incidence of non-fatal myocardial infarction or stroke—indeed, disabling strokes were somewhat commoner among those allocated aspirin. The lower confidence limit for the effect of aspirin on non-fatal stroke or myocardial infarction, however, was a substantial 25% reduction. Migraine and certain types of musculoskeletal pain were reported significantly less often in the treated than control group, but as the control group was not given a placebo the relevance of these findings was difficult to assess. There was no apparent reduction in the incidence of cataract in the treated group.The lack of any apparent reduction in disabling stroke or vascular death contrasts with the established value of antiplatelet treatment after occlusive vascular disease.     

The incorporation of 3H-fucose and 3H-mannose into the photopigment of the crayfish Procambarus clarkii

Summary Isolated crayfish retinas were incubated for 8 h in the light in a medium containing either ³H-fucose or ³H-mannose. Following this incubation, the rhabdom membranes were isolated, the pigment reduced with boranedimethylamine, and extracted with SDS detergent. The membrane-protein extract was separated by SDS-polyacrylamide gel electrophoresis. The photopigment band on the gels was identified by its fluorescence upon exposure to long wavelength ultraviolet light. Determination of the distribution of radioactivity in the gels indicated that both fucose and mannose labeled the photopigment and other glycoproteins. Hydrolysis of the sugars from the labeled photopigment bands, followed by thin layer chromatography, further confirmed that both sugars were incorporated into newly synthesized photopigment without modification. These results provide the first reported data on the partial composition of the carbohydrate moiety of an invertebrate photopigment. These findings on the crayfish photopigment are compared with data from vertebrate rhodopsin and photopigment of other invertebrates.Supported by a grant from the National Science Foundation (BNS 80-04587) and by BRSG Grant 507 RR07031 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, NIH     

THE SEPARATION OF DIFFERENT CELL CLASSES FROM LYMPHOID ORGANS : III. The Purification of Erythroid Cells by pH-Induced Density Changes

1. Mammalian erythrocytes swell as the pH of the isotonic suspending medium is lowered, as a direct consequence of the specialized permeability properties of the erythrocyte membrane. Lymphocytes and granulocytes from a variety of sources did not exhibit this property. 2. The behaviour of mouse bone marrow erythroid cells at various stages of differentiation was studied by using a change in buoyant density with pH as an index of swelling. The ability to swell with a pH drop was acquired while the cell was still nucleated. All non-nucleated cells showed swelling. Most small erythroblasts shared this property, whereas most large erythroblasts did not. 3. The density shift with pH was used to provide a purification scheme specific for erythroid cells. The bone marrow cells were first centrifuged to equilibrium in an isotonic albumin density gradient at neutral pH. Regions of the gradient containing the erythroid cells were collected, and the cells were recovered and redistributed in an albumin gradient at acid pH. The erythroid cells showed a specific density shift which removed them from contaminants. Preparations containing 90–97% erythroblasts were obtained by this technique. 4. Differentiation within the erythroid series was accompanied by a general increase in cell buoyant density at neutral pH. This density increase may have been a discontinuous process, since erythroid cells appeared to form a number of density peaks. 5. The pH shift technique, in association with established density distribution and sedimentation velocity procedures, provides a range of cell separation techniques for biological or biochemical studies of erythroid cell differentiation in the complex cell mixtures in bone marrow or spleen.