Trehalase activity and its regulation during growth of Saccharomyces cerevisiae.

Trehalase activity decreased in 95% at the onset of the transition phase of growth of S. cerevisiae. The question which we raised was whether this phenomenon was due to proteolysis or to conversion of the enzyme to a less active form (dephosphorylation). Immunological methods allowed to identify the presence of the trehalase protein during cell growth. At the same stage of growth, an increase in the non-phosphorylated enzyme was detected "in vitro". Results utilizing mutant strains also indicated that regulation occurred by interconversion of forms. The same mechanism also seems to control trehalase activity in non proliferating conditions.     

Role of tissue hypoxia as the mechanism of lactic acidosis during E. coli endotoxemia.

We compared the hemodynamic and metabolic alterations produced in rabbits by similar decreases in cardiac output created by inflating a balloon placed in the right ventricle (n = 6) with those produced by an intravenous bolus of Escherichia coli lipopolysaccharide (LPS; SEP group; n = 6). We measured O2 consumption (VO2), O2 transport (TO2), and O2 extraction ratio (ERO2) for the whole animal and also for the left hindlimb. Both groups experienced similar decreases in cardiac output, systemic TO2, and VO2 and similar increases in ERO2. For the hindlimb, TO2 was similar, but VO2 and ERO2 were lower for the SEP group 30 min after LPS administration (P less than 0.05); however, this difference disappeared during the remainder of the experiment. Arterial lactate concentration was greater (P less than 0.05) for the SEP group. There were no differences in skeletal muscle PO2, measured with a multiwire surface electrode, or in cardiac and skeletal muscle concentrations of high-energy phosphates. We hypothesize that a direct effect of LPS on cellular metabolism may have resulted in greater arterial lactate concentration for the SEP group.     

The Roberts syndrome

Summary Four siblings with the autosomal recessive Roberts syndrome are reported, and we discuss the phenotypic overlap of this syndrome with other similar radial, aplasia syndromes.     

Extraction and immunochemical assays of a tubulin-like factor in cotton seedlings

Antibodies to tubulin were prepared in rabbits by immunization with reduced-carboxymethylated calf-brain tubulin. In immunodiffusion tests the antibodies showed full cross reactivity with the immunogen as well as with native calf-brain tubulin. The same antibodies showed cross reactivity with a factor in extract of cotton (Gossypium hirsutum L.) cotyledons but there was no full immunological identity between calf-brain tubulin and this factor. A solid-phase radioimmunoassay for quantitative estimation of this plant tubulin-like factor was developed. It measured the binding of antibodies to immobilized calf-native tubulin. Competition between the unknown soluble tubulin-like factor, and immobilized tubulin was assayed at serum dilution of 1:50. Extraction conditions which preserved the antigenic properties of the tubulin-like factor from cotton cotyledons were defined. The radioimmunoassay measured quantities of the tubulin-like factor in the range of 0.1–10 g-equivalents of calf-brain tubulin. Immediately after homogenization of the tissue only 25% of the total amount of tubulin-like activity was present in soluble form, while most of it remained in the insoluble fraction. Apparent maximal solubilization was achieved spontaneously 10 h after homogenization or by treatment with guanidine hydrochloride. These results indicate that in this material, tubulin is not released immediately by homogenization but remains assembled in microtubules and-or in a bound or sequestered form.Abbreviations NRS normal rabbit serum - RCM reduced-carboxymethylated     

The value of electrocardiographic R-wave changes in exercise testing: Preexercise versus postexercise measurements

To determine the usefulness of R-wave amplitude changes during exercise testing for the diagnosis of coronary artery disease (CAD) and to understand the discrepancies that have been described in the literature regarding their value, we studied two groups of patients by means of electrocardiographic (EKG) treadmill testing and coronary arteriography. Group I was composed of 149 patients who were studied prospectively. The specificity of R-wave changes measured from preexercise to immediately postexercise (SRV(5)) was 81%, but that of R-wave changes measured from preexercise to peak exercise (URV(5)) was 46%. A group of 156 patients (Group II) evaluated retrospectively showed a high specificity for the SRV(5) (84%) and poor specificity for the URV(5) (39%). The sensitivity of the SRV(5) was 38% in Group I and 42% in Group II. Therefore, if measured during the immediate postexercise period and not at peak exercise, changes in R-wave amplitude may be of value in the diagnosis of coronary artery disease by electrocardiographic exercise testing.     

Effect of lectins on the interactions between human peripheral blood lymphocytes and monocytes

Interactions between normal human peripheral blood T lymphocytes and monocytes were investigated by measuring the in vitro cellular adherence of these cells in the presence and in the absence of mitogens. Concanavalin A (Con A), lentil lectin (Lc), and phytohemagglutinin (PHA) in mitogenic doses increased 15 to 20 times the binding of T lymphocytes to monocytes. The lectin-induced binding was similar to that produced by neuraminidase-gal-actose-oxidase treatment. A good correlation was found between the early cellular adherence induced by these lectins and by neuraminidase-galactose-oxidase and the blastogenesis of the T lymphocytes measured after 3 days of culture by [³H]thymidine uptake. However, wheat germ agglutinin (WGA), a nonmitogenic lectin, also increased the binding of T lymphocytes to monocytes. Addition of specific carbohydrates completely inhibited the cellular interactions induced by lectins. Peanut agglutinin (PNA) induced adherence of lymphocytes only after treatment of these cells with neuraminidase. Striking differences were not found between the lectin-induced adherence observed with autologous and heterologous cells. Killing of monocytes abolished entirely the lectin-induced adherence of lymphocytes, however killed T lymphocytes were still able to interact weakly with live monocytes. Dexamethasone was found to be a potent inhibitor of mitogen-induced cellular interactions.     

A trophic diversity index for presence-absence food data

Summary An index to assess trophic diversity from presence-absence food data is proposed. The index is computed according to the expression , where the 's are the frequencies of occurrence of the various prey categories. The upper and lower limits of D are derived. A test of the reliability of D was carried out by comparing D and H (Shannon's information function) values obtained from a set of twenty-three food analyses from vertebrate animals. Results show that, although a significant correlation exists between D and H, only a small fraction of H-variation is explained by D-variation. D contains two kinds of information, one referred to species richness and another relative to the degree of between-samples heterogeneity. The former is shared in common with H and this presumably explains the fairly weak correlation found between both measures.     

Liver transplantation in a patient with cholangiocarcinoma and ulcerative colitis.

A 39 year-old patient with cholangiocarcinoma and pre-existing ulcerative colitis was successfully treated by orthotopic liver transplantation. He was given low doses of prednisone and azathioprine and survived for more than 9 months, dying with tumour metastases, thrombosis of the inferior vena cava and an intra-abdominal abscess. At autopsy the homograft showed little evidence of rejection. Preoperatively the patient had septicemia. Removal of his liver was difficult. The discrepancy between donor and recipient in size of blood vessels and the presence of two hepatic arteries in the donor caused problems during the vascular anastomoses. During the operation cardiac arrest occurred. Postoperatively there were several medical and surgical problems, including intraperitoneal and gastrointestinal hemorrhage, paralysis of the right dome of the diaphragm, sinus bradycardia, massive diuresis, peroneal nerve palsy, and one major and three minor episodes of rejection, which were reversed by giving pulse doses of methylprednisolone intravenously.