The beta 1----2-D-xylose and alpha 1----3-L-fucose substituted N-linked oligosaccharides from Erythrina cristagalli lectin. Isolation, characterisation and comparison with other legume lectins

The carbohydrate moieties of Erythrina cristagalli lectin were released as oligosaccharides by hydrazinolysis, followed by N-acetylation and reduction with NaB3H4. Fractionation of the tritium-labelled oligosaccharide mixture by Bio-Gel P-4 column chromatography and high-voltage borate electrophoresis revealed that it is composed of five neutral oligosaccharides. Structural studies by sequential exoglycosidase digestion in combination with methylation analysis and two-dimensional 1H-NMR showed that the major component was the fucose-containing heptasaccharide Man alpha 3(Man alpha 6)(Xyl beta 2)Man beta 4GlcNAc beta 4(Fuc alpha 3)GlcNAcol. This is the first report of such a structure in plant lectins. Small amounts of the corresponding afucosyl hexasaccharide were also identified, as well as three other minor components. The structure of the heptasaccharide shows the twin characteristics of a newly established family of N-linked glycans, found to date only in plants. The characteristics are substitution of the common pentasaccharide core [Man alpha 3(Man alpha 6)Man beta 4GlcNAc beta 4GlcNAc] by a D-xylose residue linked beta 1----2 to the beta-mannosyl residue and an L-fucose residue linked alpha 1----3 to the reducing terminal N-acetylglucosamine residue. The oligosaccharide heterogeneity pattern for Erythrina cristagalli lectin was also found for the lectins from four other Erythrina species and the lectins of two other legumes, Sophora japonica and Lonchocarpus capassa.     

Characterization of quisqualate recognition sites in rat brain tissue usingDl-[3H]α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and a filtration assay

The binding of [³H]AMPA (Dl--amino-3-hydroxy-5-methylisoxazole-4-propionic acid), a ligand for the putative quisqualate excitatory amino acid receptor subtype, was evaluated using centrifugation and filtration receptor binding techniques in rat brain crude synaptosomal membrane preparations. Maximal specific binding of [³H]AMPA occurred in Triton X-100 treated membranes in the presence of the chaotropic agent potassium thiocyanate (KSCN). The effects of KSCN on binding were reversible and optimal at 100 mM. Supernatant obtained from detergent-treated membranes inhibited specific [³H]AMPA and [³H]kainic acid binding, suggesting the presence of an inhibitory agent which was tentatively identified as glutamate. Using centrifugation, saturation analysis revealed two distinct binding sites in both the absence and presence of KSCN. The chaotrope was most effective in increasing binding at the low affinity binding site, enhancing the affinity (K _d) without a concommitant change in the total number of binding sites. Using filtration, a single binding site was detected in Triton-treated membranes. Like the data obtained by centrifugation, KSCN enhanced the affinity of the receptor (K _d value=10 nM) without altering the number of binding sites (B _max=1.2 pmol/mg protein). The rank order of potency of various glutamate analogs in the [³H]AMPA binding assay was quisqualate > AMPA > l-glutamate > kainate > d-glutamate, consistent with the labeling of a quisqualate-type excitatory amino acid receptor subtype.l-glutamic acid diethylester, and 2-amino-7-phosphonoheptanoic acid (AP₇) were inactive. The present technique provides a rapid, reliable assay for the evaluation of quisqualate-type excitatory amino acid agonists and/or antagonists that may be used to discover more potent and selective agents.     

Migration of gall stones.

The factors influencing the migration of gall stones are ill understood. Altogether 331 patients undergoing cholecystectomy were studied prospectively. The diameters of the cystic and common bile ducts and of stones in the gall bladder and bile ducts were measured. Increasing pressure was applied to the freshly excised gall bladder in an attempt to evacuate stones through the cystic duct. Stones passed in 33 (60.0%) of patients with choledocholithiasis, 45 (67.2%) of patients with pancreatitis, and 7 (3.2%) of patients without either pancreatitis or choledocholithiasis. Stones migrated in 6 (3.0%) who had a normal cystic duct diameter (less than or equal to 4 mm) and in 46 (32.5%) with a duct over 4 mm diameter. Common bile duct stones were often larger than the diameter of the cystic duct and when reintroduced into the gall bladder would not migrate. The passage of debris (less than or equal to 1 mm) through the cystic duct bore no relation to the presence or absence of choledocholithiasis or a dilated cystic duct. Small stones (1-4 mm diameter) must migrate to initiate and facilitate further migration; some must increase in size in the common bile duct. Increased biliary pressure consequently dilates the duct system retrogradely, allowing larger stones to follow. Patients at risk of stone migration and thereby pancreatitis and jaundice have large ducts that can be detected by ultrasound assessment.     

Cardiovascular effects of training for a marathon run in unfit middle aged men.

The effects of a 30 week exercise programme on serum lipid values, blood pressure, and cardiac function were assessed in a group of sedentary men aged 35-50 training for their first marathon. Mean serum cholesterol concentration (n = 33) fell by 12% from 6.54 (SE 0.18) to 5.76 (0.15) mmol/l (mean fall 0.78 mmol/l; 95% confidence interval 0.52 to 1.04 mmol/l), serum triglyceride concentration (n = 33) by 22% from 1.56 (0.17) to 1.21 (0.09) mmol/l (mean fall 0.34 mmol/l; 95% confidence interval 0.12 to 0.56 mmol/l), and mean blood pressure (n = 27) by 10% from 102 (2) to 92 (2) mm Hg (mean fall 10 mm Hg; 95% confidence interval 7 to 13 mm Hg). These changes were not explained by changes in body composition. Peak exercise left ventricular end diastolic volume (n = 16) increased with training; as a result of this and an increased exercise left ventricular ejection fraction peak exercise cardiac output increased from 19.9 (1.2) to 23.1 (3.0) l/min (mean rise 3.2 l/min; 95% confidence interval 1.5 to 5.0 l/min). Maximum oxygen consumption increased from 33.9 (1.6) to 39.0 (1.3) ml/kg/min (mean rise 5.0 ml/kg/min; 95% confidence interval 1.8 to 8.2 ml/kg/min). This study showed favourable effects on coronary risk factors and cardiac function and supports the place of regular exercise in coronary prevention programmes.     

New ways to look at the architecture of plant cell walls : localization of polygalacturonate blocks in plant tissues

We report the use of Ni²⁺ and Co²⁺ on free-hand sections of soybean (Glycine max L.) and Bidens sp to localize polygalacturonates. In soybean only the hourglass cells of the seedcoat stain intensely. In the pod the epidermis of the outer pod wall and a few layers of subepidermal cells stain lightly, while that part of the funiculus adjacent to the seedcoat palisade epidermal cells stains heavily and the neck of the funiculus close to the pod also stains. In Bidens stem sections, the walls of the collenchyma stain most intensely.     

Survival after total-body irradiation. I. Effects of partial small bowel shielding

The small intestine of the rat was shielded during total-body irradiation (TBI) to evaluate the effects of radiation dose and length of intestine shielded on survival. Sprague-Dawley rats were anesthetized in groups of 10. Using aseptic surgical procedures 80, 40, 20, or 10 cm, or none of the proximal or distal small intestine were temporarily exteriorized and shielded during irradiation with photons from an 18 MeV linear accelerator. Less than 17% of the dose was delivered to the shielded intestines. In unshielded animals deaths occurred from Days 4 to 6 with 13, 15, or 17 Gy and from Days 8 to 30 with 9, 11, and 12 Gy. However, in all animals exposed to 15 Gy with all or part of the small intestine shielded, survival was increased to between 5 and 9 days. Shielding of the distal small intestine was more effective in prolonging survival than shielding of the proximal small intestine. The previously identified target of radiation damage in the small intestine is the crypt stem cell. In this study, the analysis of histological specimens of shielded and irradiated small intestine suggested that humoral factors also influence intestinal histology and survival after irradiation. These humoral factors are thought to originate from the irradiated body tissues, the shielded proximal intestine, and the shielded distal intestine. Further studies are required to identify these factors and to determine their mode of action and their therapeutic potential after radiation damage to the small intestine.     

Behavioral endocrinology of male rats with periodic sexual contacts with exclusive or varied females

Sexual contact keys a profound series of acute and chronic changes in males that, presumably, are orchestrated by acute pulsatile release of hormones. An experimental paradigm is reported in which male rats were paired periodically with either the same or different estrous females to receive identical amounts of copulatory experiences. Results confirmed the hypothesis that exposure to an unfamiliar female would induce a different endocrine response which would be reflected in various androgen-sensitive systems. The "successively polygynous" males showed more sexual behavior than "monogamous" males, and their respective females solicited the males differently, as well. Circulating levels of testosterone were higher immediately after sexual contact with an unfamiliar than with a familiar female partner. There were no differences in testosterone titers among the groups when the animals were killed at either 2 or 7 weeks after the final copulatory experiences. Yet, necropsies at 2 weeks postcopulation revealed that primary and secondary sex structures from polygynous males clearly were larger. Differences between the two experimental groups were reduced after 7 weeks of sexual rest, yet, polygnous males continued to show a different structural profile than the other groups. Conclusions were that males may experience greater activation of androgen-sensitive behavior and physiology following qualitatively different sexual contacts.