Critical water temperature during water immersion at various atmospheric pressures

The present work was undertaken to determine the effect of atmospheric pressure [ranging from a high altitude of 4,300 m above sea level or 0.6 atmospheres absolute (ATA) to depths of 10 m deep or 2 ATA] on the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 2 h without shivering, of the unprotected subject during water immersion. Nine healthy males wearing only shorts were subjected to immersion to the neck in water at 0.6, 1, and 2 ATA while resting for 2 h. Continuous measurements included esophageal (Tes) and skin (Tsk) temperatures, direct heat loss from the skin (Htissue), and insulation of the tissue (Itissue). The Tcw was significantly higher at 0.6 ATA than 1 and 2 ATA: however, Tcw at 1 ATA was identical to that at 2 ATA. The metabolic heat production remained unchanged among the pressures. During the 2-h immersion in Tcw, Tes was identical among all atmospheric pressures: however, Tsk was significantly higher (P less than 0.05) at 0.6 ATA and was identical between 1 and 2 ATA. The overall mean Itissue was near maximal during immersion in Tcw in each pressure, and no difference was detected among the pressures. However, Itissue at the acral extremities (arm, hand, and foot) decreased significantly at 0.6 ATA, and subsequently heat loss from these parts was increased, which elevated an extremity-to-trunk heat loss ratio to 1.4 at 0.6 ATA from 1.1 at 1 and 2 ATA.(ABSTRACT TRUNCATED AT 250 WORDS)     

A method for measuring the amount of retrogradely transported HRP in the rat masseteric motoneuron using Mesulam's HRP histochemical protocol and an image processing system. An investigation of the effect of dopamine receptor antagonists on the retrograde transport of HRP

We developed a method for a determination of the amount of retrogradely transported HRP in the rat masseteric motoneuron using a modification of Mesulam's HRP histochemical protocol and an image processing system combined with a light microscope and a television camera. To test the validity and reproducibility of the new method, a quantitative comparison of the amount of dark blue granules of HRP-product in the cell body of masseteric motor neurons was performed between the right and left trigeminal motor nuclei of 70 rats, which resulted in no significant difference. An additional study used the method was made of the effects of administration of five dopamine receptor antagonists with different biochemical and pharmacologic properties on retrograde transport of HRP in the rat masseteric motoneuron. As a result, chlorpromazine, haloperidol, SCH 23390, and sulpiride significantly enhanced retrograde transport of HRP as against domperidone which showed no significant change in the transport. A possible regulatory system for retrograde transport of HRP in the masseteric motoneuron was discussed in relation to the action of the dopamine receptor.     

Postmortem changes in uric acid and ascorbic acid in human cerebral cortex tissues excised after cardiac death

There has been no report on the determination of uric acid (UA) in human brain and heart tissues. UA and ascorbic acid (AA) in human cerebral cortex and heart tissues excised after cardiac death have been studied by reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). It has been found that the levels of AA and UA in the human cerebral cortex tissues tend to decrease and increase, respectively, after cardiac death as a function of time between death and forensic operation. In addition, it has been found that there is no special relationship between UA levels in human heart tissues and time after cardiac death, also that the UA levels in the heart are high as compared with those in human cerebral cortex tissues. We have emphasized that the HPLC-ECD method is useful in determining UA and AA in mammalian tissues by one-time chromatography to gain a better understanding of the relationship between disease and serum urate level.     

Absorbance spectral change of the cytochrome P-450S21-phenylisocyanide complex upon binding of reduced NADPH-cytochrome-P-450 reductase.

Reduction of cytochrome P-450S21 (SF) (SF, substrate-free; purified from bovine adrenocortical microsomes) with sodium dithionite (Na2S2O4) in the presence of phenylisocyanide produced a ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex with Soret absorbance maxima at 429 and 456 nm. On the other hand, when a preformed ferric cytochrome P-450S21 (SF)-NADPH-cytochrome-P-450 reductase (Fp2) complex was reduced chemically or enzymatically under the same conditions, the absorbance spectrum of the ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex changed drastically, as characterized by an increase in absorbance intensity at 429 nm and a decrease at 456 nm. Similar spectral changes were observed by addition of reduced Fp2 to the preformed ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex. Experiments to reduce a ferric cytochrome P-450S21 (SF)-phenylisocyanide complex with sodium dithionite in the presence of various amounts of Fp2 showed that; (1), the spectral change reached maxima for both absorption increase at 429 nm and decrease at 456 nm when cytochrome P-450S21 and Fp2 were previously mixed at the cytochrome P-450S21:Fp2 ratio of 1:5; (2), the spectral change was suppressed in 300 mM potassium phosphate buffer (pH 7.4). These results suggest that the absorbance spectral change is due to a conformational change around the heme moiety induced by association with reduced Fp2.     

Soybean Lipoxygenase L-4, a Component of the 94-kilodalton Storage Protein in Vegetative Tissues: Expression and Accumulation in Leaves Induced by Pod Removal and by Methyl Jasmonate

A lipoxygenase L-4 gene was isolated from a soybean genomiclibrary. The amino acid sequence of lipoxygenase L-4 is highlyhomologous with the partial amino acid sequence of the 94-kDavegetative storage protein, vsp94, found in paraveinal mesophyllcells in the leaves of depodded soybean plants. No L-4 expressionwas observed in maturing seeds. The L-4 gene is highly expressedin the vegetative tissues of young seedlings, including cotyledons,hypocotyls, roots and primary leaves. L-4 expression followedthe same pattern as lipoxygenase activity in cotyledons peaking3 to 5 days after germination, and returning to a basal levelby 9 days after germination. L-4 gene expression was low inthe roots, stems and leaves of 10-week-old plants. Exposureof 4-week-old plants to atmospheric methyl jasmonate increasedL-4 mRNA in leaves. Continuous pod removal from 7-week-old plantsover a 2 week period resulted in dramatic accumulation of L-4mRNA in leaves. Accumulation of the L-4 protein and three otherlipoxygenase fractions in the leaves of depodded plants wasdemonstrated by ion exchange chromatography. These results indicatethat lipoxygenase L-4 is a component of vsp94. (Received May 31, 1993; Accepted August 9, 1993)     

Isolation of a new cDNA clone encoding an Rh polypeptide associated with the Rh blood group system

We searched for a human chromosome that would restore the cholesterol metabolism in 3T3 cell lines (SPM-3T3) derived from homozygous sphingomyelinosis mice (spm/spm). Mouse A9 cells containing a single copy of pSV2neo-tagged chromosomes 9, 11, or 18 derived from normal human fibroblasts served as donor cells for transfer of human chromosomes. Purified A9 microcells were fused with SPM-3T3 cells, and the microcell hybrids were selected in medium containing G418 antibiotics. The microcell hybrids that contained human chromosomes 9, 11, or 18 in a majority of cells were examined. The accumulation of intracellular cholesterol in the microcell hybrids containing a chromosome 18 decreased markedly, whereas in the microcell hybrids containing either chromosomes 9 or 11 it was similar to that in SPM3T3 cells. The SPM-3T3 cells with an intact chromosome 18 were further passaged and subcloned. Clones which again accumulated intracellular cholesterol had concurrently lost the introduced chromosome 18. The abnormal accumulation was associated with a decrement in the esterification of exogenous cholesterol. These findings suggest that the gene responsible for the abnormal cholesterol metabolism in the spm/spm mice can be restored by a hu man chromosome 18. The gene was tentatively mapped on 18pter18p11.3 or 18q21.3qter that was lost during subcloning, thereby resulting in reaccumulation of the intracellular cholesterol.