Isolation of two pure polysaccharides from the hemicellulose of slash pine (Pinus elliottii)

Two pure, acidic polysaccharides have been isolated from the hemicellulose of slash pine in yields of 1–2% and 4–5%. Their properties are compared, and the structure of one of them has been investigated by methylation analysis. The results indicate that the glycan is a β-D-(1→4)-linked xylan chain with many branch points. 4-O-Methyl-D-glucopyranosyluronic acid, L-arabinofuranose, and D-xylopyranose residues occur as non-reducing end groups. The uronic acid occurs as single-unit attachments to the main chain. Some of the D-xylose residues in the polysaccharide are doubly branched. The total hemicellulose components of the wood probably represent a complex mixture of chemical types, from which the two pure fractions described above may be separated fortuitously by careful, fractional precipitation.     

Branched-chain glycosyl α-amino acids : Part II. Synthesis of 2-D- and 2-L-(3-deoxy-1,2:5,6-di-O-isopropylidene-α-D-glucofuranos-3-yl)glycine. Analogs of the sugar moiety of the polyoxins

Stereospecific hydroxylation of 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-trans-and 3-C-cis-(methoxycarbonylmethylene)-α-D-ribo-hexofuranose (2 and 3, respectively), with potassium permanganate in pyridine afforded 3-C-[S- and R-hydroxy-(methoxycarbonyl)methyl]-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, (6 and 7, respectively), in a combined yield, after chromatography, of 43%. Selective formation of monomethanesulfonates (9a and 10a) and p-toluenesulfonates (9b and 10b), followed by treatment with sodium azide and reduction of the azide, afforded the methyl 2-D-(and 2-L-)(3-deoxy-1,2:5,6-di-O-isopropylidene-α-D-glucofuranos-3-yl)-glycinates (12a and 13a, respectively). Basic hydrolysis of the latter compounds yielded 2-D- and 2-L-(3-deoxy-1,2:5,6-di-O-isopropylidene-α-D-glucofuranos-3-yl)glycine (12b and 13b, respectively). The structures of the glycosyl amino acids were correlated with that of L-alanine by circular dichroism.     

Effect of Externally Applied Pressure on Femoral Vein Blood Flow

The effect of incremental increases in external pressure, applied to the leg, on blood volume flow in the femoral vein was studied in dogs. Clinical investigation of external pressure increases was also carried out on nine patients undergoing surgery for varicose veins. An external pressure between 5 and 15 mm. Hg caused a sustained increase in mean femoral vein flow both in a control and in the compressed limb. Above 15 mm. Hg external pressure flow decreased in the compressed limb but was maintained at an increased level in the control limb.If external compression is to be used to prevent and treat deep vein thrombosis its application must be carefully controlled.     

Freeze-drying characteristics ofSaccharomyces cerevisiae andSaccharomyces carlsbergensis

The dispersal of yeast clumps to the unicellular state by certain sugars, does not increase the percentage survival after freeze-drying. Neither are those changes in cell-wall composition which occur upon ageing of the cell, and which are detectable by means of snail-gut enzymes, related to this cellular property. However, pre-treatment, with -mercaptoethanol, of a strain ofSaccharomyces carisbergensis increased the survival rate. This may be due to the reduction of certain sites in the cell wall. The oxygen consumption of yeast cultures before and after freeze-drying, agree with the hypothesis that low viabilities can arise from localized cellular damage which prevents cell reproduction by budding.     

Anatomy of the arteries of the head in the domestic fowl

The anatomy of the cephalic arterial system in the fowl was studied in 24 specimens by means of latex-injected preparations and by dissection. Branches of the external carotid artery supply the extracranial regions. The vertebral arteries unite with the occipitals and have no major communications with the encephalic system. Blood can reach the brain directly from the internal carotid artery and indirectly by way of the extensive cerebral-extracranial anastomoses; especially prominent are those to the palatine and sphenomaxillary arteries from the maxillary and facial branches of the external carotid artery. A large external ophthalmic artery supplies the temporal rete and eye musculature, and an internal ophthalmic artery links the rete and the cerebral vessels. The circle of Willis is incomplete both anteriorly and posteriorly; the anterior cerebral arteries do not unite and the basilar artery is generally asymmetrical in origin. The basilar artery tapers caudally and is continued as the ventral spinal artery.