Reduction of postischemic edema with hyperbaric oxygen

In recent years, reports have shown positive effects of hyperbaric oxygen (HBO) treatment in posttraumatic circulatory insufficiency of the extremities. A tourniquet model for temporary ischemia was used to examine such treatment in rats. The circulation of the rat hindlimb was interrupted for 3 hours, while the contralateral uninjured leg served as control. There was a significant (p less than 0.001) postischemic edema in the tourniquet leg up to 48 hours after restoration of circulation. One group of animals received treatment with hyperbaric oxygen at 2.5 atmospheres absolute (ATA) for 45 minutes after release of the tourniquet. This significantly reduced (p less than 0.001) the postischemic edema, and the reduction persisted for 40 hours after the last treatment. It is concluded that hyperbaric oxygen reduces postischemic edema. Hyperbaric oxygen may therefore be useful as an adjuvant in the treatment of acute ischemic conditions when surgical repair alone fails or is not sufficient to reverse the ischemic process.     

Simplified purification and testing of colloidal gold probes

A novel efficient method for purifying and testing colloidal gold probes has been developed. The method consists of concentrating colloidal gold particles conjugated to IgG or protein A in dialysis bags over silica gel and purifying them by gel chromatography on small columns of Sephacryl S-400. Fractions collected are tested by paper immunocytochemical models. Comparisons to gold probes purified by conventional ultracentrifugation documents that ultrastructural staining intensities and total yield of gold probes is the same, but that the chromatographically purified gold probes are less prone to aggregation or clumping. The method has been extensively used for preparing conjugates of 5, 10 or 15 nm gold particles with antirabbit immunoglobulins but has also been exploited for preparing streptavidin-gold conjugates, protein A-gold conjugates and antirabbit immunoglobulin-silver conjugates.     

Identification of the in vivo and in vitro phosphorylation sites of rat liver fructose 1,6-bisphosphatase

Rat liver fructose 1,6-bisphosphatase appears to be unique in that it extends 24-26 residues beyond the COOH-terminal amino acid of other mammalian fructose 1,6-bisphosphatases and this extension contains phosphorylation sites. Using as a frame of reference the 335-residue sequence of pig kidney fructose 1,6-bisphosphatase (Marcus, F., Edelstein, I., Reardon, I., and Heinrikson, R. L. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 7161-7165), the rat liver enzyme would extend to residue 361. Limited proteolysis in the COOH-terminal region of the molecule with chymotrypsin, trypsin, or both sequentially, led us to establish that the phosphorylation sites are located at Ser residues 341 and 356. The in vitro phosphorylation of purified rat liver fructose 1,6-bisphosphatase by the catalytic subunit of cyclic AMP-dependent protein kinase results in modification at both residues, although the major site of phosphorylation (61%) is at Ser-341. In contrast, rat liver fructose 1,6-bisphosphatase purified from animals that had been injected with [32P] phosphate contains most of the label (81%) at Ser-356.     

Activation and growth requirements for cytotoxic and noncytotoxic T lymphocytes

The number and nature of the "signals" required for lymphocyte activation have been so repetitively and academically discussed over the last 15 years that both the readers and the authors appear exhausted by such exercises. Yet, what may be considered to be the essential question, the basis for self-nonself discrimination, remains to be clarified. Since it has been established that clonal expansion and maturation to effector functions are brought about by polyclonally ("immunologically nonspecific") active factors, it is obvious that the crucial "step" in this context is the initial interaction of antigen with specific receptors of immunocompetent lymphocytes. This initial discriminatory event appears to proceed differently on the various cell subsets. We first deal with the mechanism of induction and growth of cytotoxic-T-lymphocyte precursors, and then discuss the inductive requirements leading to proliferation of T helper cells.     

Prostaglandin production by dispersed granulosa and theca interna cells from porcine preovulatory follicles

Prepubertal gilts were treated with 750 IU pregnant mares' serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Dispersed granulosa (GC) and theca interna (TIC) cells were prepared by microdissection and enzymatic digestion from follicles obtained 36, 72 and 108 h after PMSG treatment and incubated for up to 6 h in a chemically defined medium in the presence or absence of arachidonic acid, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and indomethacin. Production of prostaglandin E2 (PGE) and prostaglandin F2 alpha (PGF) was measured by radioimmunoassay. Both GC and TIC had the capacity to produce prostaglandins, with production by each cell type increasing markedly with follicular maturation. PGE was the major prostaglandin produced by both cellular compartments. Only PGE production by GC was consistently enhanced by addition of arachidonic acid to the incubation medium. Neither cell type was responsive to FSH and LH in vitro. Indomethacin inhibited the production of PGE and PGF by both cell types. These results provide convincing evidence for an intrafollicular source of prostaglandins and indicate that both cellular compartments contribute significantly to the increased production of prostaglandins associated with follicular rupture.     

Photosynthesis and nitrogen utilization in exponentially growing nitrogen-limited cultures of Lemna gibba

The photosynthetic performance and nitrogen utilization of Lemna gibba L. G3 adapted to limited nitrogen supply was studied. The plants were adapted to two levels of nitrogen limitation where the nitrogen addition rates were calculated to sustain relative growth rates (RGR) of 0.15 day^?1 and 0.25 day^?1, respectively. The photosynthetic performance of these cultures was compared to nitrogen-sufficient cultures with an average RGR of 0.32 day^?1. Plants transferred from nitrogen-sufficient conditions attained RGR values corresponding to the nitrogen addition rates after 6 to 10 days. Light-saturated net photosynthesis declined during adaptation according to the drop in growth rate, and a concomitant decrease in the respiration rate was recorded. The efficiency of net photosynthesis on a dry weight basis increased with increased nitrogen supply, whereas it was the same in all cultures when expressed on a chlorophyll basis. The light compensation point was unaffected by the nitrogen regime. Limited nitrogen supply resulted in an increased proportion of dry matter in the roots, which led to decreased leaf area ratios. The net assimilation rates also decreased, but not to the same extent as the leaf area ratios. Growth-limiting amounts of nitrogen were added to the cultures once daily, and the net influx of N was higher than the requirement for N, also in adapted cultures with a steady growth rate. This resulted in transient, periodic fluctuations in the NO₃^?, NH₄⁺ and amino acid pools. Also the rates of NO₃^? reduction and NH₄⁺ assimilation fluctuated as did the amino acid assimilation which paralleled NH₄⁺ assimilation. The role of flux rates over the plasmalemma and tonoplast for control of nitrogen assimilation rates are discussed.     

immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma

The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA.     

Genetic polymorphism of the sixth component (C6) of rat complement

The complement protein C6 has been shown to be genetically polymorphic in the rat. Isoelectric focusing of plasma samples from 19 inbred strains demonstrated two electrophoretically distinguishable migration patterns, each consisting of three bands. Breeding studies with the use of the BN and DA strains showed that the C6 patterns were inherited in a manner consistent with the co-dominant autosomal expression of two alleles (C6 A and C6 B). The distribution of the C6 alleles in a backcross mating was compared with eight independently segregating marker genes: RT1.A, RT2, Gdc -1, Igk-1, Hbb, Svp-1, Fh-1, and Es-6. There was no detectable linkage between C6 and any of these eight loci.     

Olive Pink and the Encounter with the Academy

Olive Pink studied anthropology at the University of Sydney under Professor A.P. Elkin. Although she did fieldwork among the Northern Aranda and Wailbri of Central Australia, she became disenchanted with anthropology and lived a reclusive life in Alice Springs. In this paper I present a brief outline of her life, particularly during the 1930's I point to the problems she encountered and suggested that she needs to be relocated within her discipline.     

Synthesis of mannose oligosaccharides via reversal of the α-mannosidase reaction

Summary Three naturally occurring isomers of the disaccharideO--d-mannosyl-d-mannoside were synthesized by reversing the hydrolytic activity of jack bean -mannosidase at 75°C in a very high concentration of mannose. Higher oligosaccharides were also obtained at the later stages of the reaction. The maximum total yield of disaccharides was 37% (w/w) based on the total amount of saccharides.