Evaluation of structural and secretory glycoconjugates in normal human jejunum by means of lectin histochemistry

Summary The labelling pattern of eight lectins was studied in jejunal samples from ten normal subjects, in order to define the normal distribution of structural and secretory glycoconjugates in the small bowel.The following lectins were studied by means of a peroxidase technique on formalin-fixed samples: Arachis hypogaea, Ricinus communis, Canavalia ensiformis, Lens culinaris, Phaseolus vulgaris, Triticum vulgaris, Ulex europaeus, Dolichos biflorus. Phaseolus vulgaris reacted with goblet cell mucus throughout the villus-crypt axis.Conversely Ulex europaeus, Dolichos biflorus and Triticum vulgaris lectin labelling of globet cells appeared to be confined to the upper part of the villi. This finding suggests that during cell migration from crypt to villus tip, the continuing maturation of goblet cells is associated with the differentiation of secretory carbohydrates, which probably parallels the cell maturation cycle. Lectin histochemistry appears to be a reliable tool for the study of structural and secretory glycoconjugates in the jejunal mucosa, and might be of value in the study of diseases in which the cell-maturation cycle in the small bowel is altered.     

Inflammatory process caused by intraperitoneal injection of polyester in the rat: chemotactic activity in lavage fluid from the cavity

Minced polyester threads introduced into peritoneal cavity of guinea pigs or rats cause a granulomatous inflammation with evidence of macrophage stimulation. Chemotactic agents play an important role in the inflammatory reaction; they may be exogenous and/or endogenous. These are released locally by the cells involved in inflammation. In this paper the chemotactic effects of the peritoneal fluids from rats bearing the polyester inflammatory process, have been studied on PMN cells "in vitro". The peritoneal cavity fluids were obtained by washing the cavity of untreated rats or rats intraperitoneally injected with polyester, 1, 3, 7, 14 days after the intraperitoneal injection. The chemotactic response was assayed by employing modified chemotaxis Boyden chambers (Blind Well Neuro Probe) and polymorphonuclear leukocytes from normal or treated rats. Quantification of the migration was calculated by chemotactic index (A/B) (B = random migration, A = chemotaxis). The results demonstrated that the peritoneal fluids taken 3 and 7 days after the intraperitoneal polyester injection, elicit an evident chemotaxis response greater than that showed by peritoneal fluids from control rats. It is suggested that chemotactic factors can be produced and released by mononuclear cells involved in the inflammatory process.     

Positive interaction between leukotriene C4 and histamine and other mediators on vascular tissues

The interaction of leukotriene C4 (LTC4) with the contractile activity of histamine (H), serotonin (5HT) and norepinephrine (NE) has been investigated in isolated vascular preparations. Threshold concentration of LTC4 (5 X 10(-9) M) significantly potentiated the vasoconstricting effect of these compounds on guinea-pig pulmonary artery (GPPA). This phenomenon was long-lasting for H since it was still present 40 min after LTC4 had been washed. FPL-55712 (10(-5) M) counteracted the increased H response on GPPA induced by LTC4. Potentiation of H activity due to LTC4 was also observed on guinea-pig thoracic aorta (GPTA) indicating that LTC4-induced hyperreactivity is not a phenomenon restricted to the pulmonary vascular bed. In the experiments carried out in presence of indomethacin (3 X 10(-6) M), LTC4 still potentiated H-induced vasoconstriction on GPPA, however the time course of the phenomenon was significantly shorter than that observed in absence of the cyclooxygenase inhibitor. The contractile activity of H and NE on guinea-pig portal vein (GPPV) was not potentiated by LTC4. These results demonstrate that LTC4 induces hyperreactivity of the arterial vascular tissue to vasoactive compounds and suggest that cysteinyl-leukotrienes may have pathological significance in the hemodynamic changes occurring during anaphylactic reactions. Preliminary experiments carried out on human intralobar pulmonary artery strongly support this hypothesis.     

Turkey muscle acylphosphatase: purification and comparative studies

Turkey muscle acylphosphatase is strongly bound to anti-(horse muscle acylphosphatase ) antibodies covalently linked to an agarose resin. This permits use of an affinity chromatography step in the purification, which increased the final yield and allowed us to isolate three different molecular forms of the enzyme. Form 1 is a mixed disulfide between the polypeptide chain and glutathione; form 3 is an S-S dimer of the polypeptide chain present in form 1, while form 2, present in a very low amount, consists of a polypeptide chain quite similar in aminoacid composition to that found in form 1. The three molecular forms show very similar kinetic parameters. The comparison of these molecular forms with those isolated from horse muscle showed similar kinetic properties but different structural features.     

Differences between observed and predicted energy costs at rest and during exercise in three subsistence-level populations

Estimates of daily energy expenditure are important for many areas of research in human ecology and adaptability. The most common technique for estimating human energy expenditure under field conditions, the factorial method, generally relies on activity-specific energy costs derived from published sources, based largely on North American and European subjects. There is concern that such data may not be appropriate for non-Western populations because of differences in metabolic costs. The present study addresses this concern by comparing measured vs. predicted energy costs at rest and during sub-maximal exercise in 83 subjects (52 males, 31 females) from three subsistence-level populations (Siberian herders and high-land and coastal Ecuadorian farmers). Energy costs at rest (i.e., lying, sitting and standing) and while performing a standard stepping exercise did not significantly differ among the three groups. However, resting energy costs were significantly elevated over predicted levels (+16% in men, +11% in women), whereas exercising costs were comparable to predicted values (?6% in men, +3% in women). Elevations in resting energy needs appear to reflect responses to thermal stress. These results indicate that temperature adjustments of resting energy costs are critical for accurately predicting daily energy needs among traditionally living populations. o 1996 Wiley-Liss, Inc.     

A chlorinated phenylpyrrole antibiotic fromActinoplanes

Two chlorophenyl-containing antibiotics have been isolated from a strain ofActinoplanes (ATCC 33002). Antibiotic A 15104 Y is a chlorinated phenylpyrrole compound whose structure has been confirmed by chemical synthesis. Antibiotic A 15104 Z is a chlorophenol derivative for which a structural formula is proposed on the basis of its physicochemical properties. A 15104 Y shows antimicrobial activity against Gram-positive, Gram-negative, and acid-fast bacteria, yeasts, fungi, and protozoa, while A 15104 Z possesses a low activity against Gram-positive bacteria andTrichophyton. A 15104 Y has a weak activity in curing experimentally infected mice, at a dose that is one-fifth the LD₅₀ for the same species. This is the first example of a chloropyrrole derivative isolated from an actinomycete.     

Purification of horse muscle acylphosphatase antibodies by affinity chromatography

Horse muscle acylphosphatase antibodies were obtained by immunizing rabbits with the highly purified antigen cross-linked with glutaraldehyde. Specific antibodies were purified from the immunoglobulin fraction by affinity chromatography using a matrix coupled with the pure antigen as immunoadsorbent. The purified antibodies were partially characterized by immunodiffusion and immunoprecipitin techniques. These antibodies could be used to study aspects of the muscle acylphosphatase structure, localization and other biological properties.     

The epoxide hydrolase catalyzed hydrolysis of trans-3-bromo-1,2-epoxycyclohexane. A direct proof for a general base catalyzed mechanism of the enzymatic hydration

The hydrolysis of (±)-$\text{trans}$-3-bromo-1,2-epoxycyclohexane in the presence of rabbit liver microsomes was investigated, and found to yield, beside $\text{c}$-3-bromocyclohexane-$\text{r}$-1,$\text{t}$-2-diol, 2,3-epoxycyclohexanol. It was demonstrated that the latter compound was the only product of the enzymatic reaction, whereas the diol resulted from a non enzymatic hydration in the reaction medium. These data provide the first direct proof for a general base catalysis in the enzymatic epoxide hydration, previously hypothesized on the basis of several lines of indirect evidence, and disprove alternative mechanisms involving protonation of the oxirane oxygen.