Comparison of vascular hemodynamics in experimental models of microvascular anastomoses

Blood flow was measured in the canine saphenous artery using electromagnetic flowmetry. Significant increase in blood flow was noted after occlusion of the distal femoral artery. However, after raising a saphenous island flap there was no significant change in the blood flow before and after distal femoral artery occlusion. The flap peripheral resistance and blood flow were compared after end-to-end and end-to-side anastomosis and no statistical difference was noted.     

Status of reduced glutathione in primary cultures of rat hepatocytes and the effect on conjugation of benzo[a]pyrene-7,8-dihydrodiol-9,10-oxide

The intracellular level of reduced glutathione (GSH) and GSH conjugation have been investigated in primary cell cultures of hepatocytes isolated from control rats, phenobarbitone (PB) and 3-methylcholanthrene (MC) treated rats. The data demonstrate that in all cell cultures the GSH concentrations show a triphasic pattern: (i) within 1 h of culture an initial marked decrease to 50% of the levels found in fresh hepatocytes; (ii) recovery of GSH concentrations to above the levels observed in fresh cells. This occurs after 6 h in culture with control cells and after 10-24 h with cells from either PB or MC treated rats and was most prominent in cells from PB-treated rats. (iii) A slow decline to between 30 and 40 nmol GSH/mg protein from 24 to 96 h in culture. Synthesis of GSH was slower in cultured cells from PB treated rats and this was confirmed by the resynthesis rates when diethylmaleate (DEM) was used to deplete GSH. The formation of GSH conjugates with racemic 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) was measured in control cells in suspension and after 3 and 24 h in culture. Despite the decrease in GSH concentrations observed between 1 and 4 h after culture, the conjugation rates were not decreased.     

Early Intermediate State of Transforming Deoxyribonucleic Acid During Uptake by Bacillus subtilis

Examination of the effects of ethylenediaminetetraacetic acid (EDTA) on uptake of transforming deoxyribonucleic acid (DNA) by Bacillus subtilis allowed definition of a new intermediate state of transforming DNA during uptake. Markers in this state, termed "EDTA-resistant," are bound to the cell, are sensitive to inactivation by deoxyribonuclease, but may become deoxyribonuclease-resistant despite the addition of excess EDTA. Markers become EDTA-resistant quadratically with time after the addition of DNA to a competent culture, but linearly after exposure of competent cells to a brief pulse of DNA. An attractive model consistent with these findings is that EDTA blocks only the initiation of entry of a molecule of DNA.     

Effects of high altitude exposure on components of blood and urine in mountaineers

Physiological correlations with impaired or umimpaired performance at high altitude were sought among 24 blood and urine parameters measured in 50 mountaineers and 21 observers before (preclimb) and after (postclimb) expeditions on Mt. McKinley. Values and per cent changes were compared for five degrees of impairment at high altitude. Average preclimb values were all near established normal levels and no correlations with subsequent involvement at high altitude were found. Postclimb samples contained more Hb, PCV, urea, LDH, and HBD and less bilirubin (P < 0.05). But no association was found between degrees of altitude impairment and preclimb/postclimb changes in any of the 24 blood and urine parameters. Additional results from samples collected at 4300 m showed "weaker" mountaineers excreted 1/4 as much Na in urine and had 50% more serum FFA concentration than stronger mountaineers.

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Zusammenfassung Bei 50 Bergsteigern und 21 Beobachtern wurden vor und nach einer Expedition zum Mt. McKinley (Alaska) für 24 Parameter im Blut und Harn die Beziehungen zur Abschwächung der Leistung in grosser Höhe untersucht. Zum Vergleich wurden 5 Grade von unbeeinflusster bis schwerer Schädigung in der Höhe verwendet. Die mittleren Werte vor dem Aufstieg lagen alle im Bereich der Normbreite. Beziehungen zu nachfolgenden Komplikationen in der Höhe bestanden nicht. Nach dem Aufstieg waren Hgb, Hämatokrit, Harnstoff, LDH, Hydroxybutyric Dehydrogenase erhöht und Bilirubin erniedrigt (P < 0, 05). Es liess sich jedoch für keinen Parameter eine Beziehung zwischen dem Ausmass der Höhenschädigung und den Veränderungen vor und nach dem Aufstieg nachweisen. Zusätzliche Ergebnisse von Proben, die in 4300 m Höhe gesammelt wurden, ergaben, dass schwache Bergsteiger ein Viertel soviel Na im Harn ausschieden und 50% mehr freie Fettsäuren im Blut aufwiesen als starke Bergsteiger.

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Resume On a mesuré 24 paramètre du sang et de l'urine de 50 alpinistes et 21 observateurs avant et après l'ascension du Mont McKinley (Canada). On a établi ensuite la corrélation physiologique existant entre ces paramètres et une diminution éventuelle des performances. Les valeurs absolues et le taux de modification ont été comparés à 5 degrés de diminution des capacités physiques à haute altitude. Les valeurs moyennes des analyses faites avant l'ascension ont toutes été voisines du niveau normal et on n'a pas constaté de corrélation avec les performances individuelles subséquentes. Les échantillons recueillis après l'ascension contenaient davantage de Hb, PCV, urée, LDH, et HBD, mais moins de bilirubine (P < 0, 05). On n'a cependant trouvé aucune relation entre le degré de diminution des performances et les modifications d'aucun des 24 paramètres retenus du sang ou de l'urine avant et après l'ascension. Des échantillons prélevés à 4300 m d'altitude ont montré que les alpinistes peu aguerris ne sécrétaient que le 1/4 du Na par l'urine, mais avaient 50% d'acides gras libres de plus dans le sang que les montagnards les plus résistants.

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Work supported by Themis Contract No DADA 17-68-C-8018     

Structural investigations on the lignin–carbohydrate complexes of Lolium perenne

1. Lignin-carbohydrate complexes isolated from leaf blade, leaf sheath and stem tissue of ryegrass by extraction with dimethyl sulphoxide were examined by fractionation procedures. Although the complexes are heterogeneous, heterogeneity is shown only in the ratio of the individual monosaccharide residues and not in the ratio of lignin to carbohydrate. 2. The molecular weight of the complexes is high (>/=150000), but chemical modification by alkaline hydrolysis, borohydride reduction or lead tetra-acetate oxidation does not drastically decrease it. Low-molecular-weight fragments released by alkaline treatment were shown to contain acetic acid, ferulic acid and p-coumaric acid. 3. On the basis of the chemical stability of the complexes, it is postulated that at least three types of bonding may be present between lignin and carbohydrate, namely one cleaved on borohydride reduction, another cleaved by alkali and a linkage resistant to alkali. 4. The carbohydrate portion of the complexes is composed of beta-(1-->4)-linked d-glucose residues (cellulose) and beta-(1-->4)-linked chains of xylose residues. Side chains involving arabinose and galactose residues are linked to C-3 of some of the xylose residues. 5. How the components of the complexes are held together is not certain, but it is suggested that the phenolic acids may act as cross-linking agents.