Inactivation of factor Va by plasmin

The inactivation of Factor Va by plasmin was studied in the presence and absence of phospholipid vesicles and calcium ions. The cleavage patterns of bovine Factor Va and its isolated subunits were analyzed using polyacrylamide gel electrophoresis, and the progress of inactivation was monitored by clotting assays and measurements of prothrombin activation using 5-dimethylaminonaphthalene-1-sulfonylarginine-N-(3-ethyl-1,5-penta nediyl)amide. In addition, the ability of prothrombin and Factor Xa to protect Factor Va from inactivation by human plasmin was examined. The data presented indicate that the cofactor Factor Va is inactivated rapidly upon its interaction with human plasmin. The rate of inactivation is significantly enhanced in the presence of phospholipid vesicles, suggesting that the inactivation process is a membrane-bound phenomenon. The isolated D component (heavy chain of factor Va) was found to be slowly degraded by human plasmin, giving rise to cleavage products different from those obtained with activated protein C and Factor Xa. However, the 48- and 30-kDa fragments obtained from human plasmin degradation of component E (light chain of Factor Va) appear to be similar to those obtained following the proteolysis of the same subunit by activated protein C and Factor Xa.     

Synthesis of acetone glycerol acyl esters by immobilized lipase ofMucor miehei

Summary The applications of immobilized lipase ofMucor miehei for the synthesis of acetone glycerol acyl ester from acetone glycerol and fatty acid, which is the first step for monoglyceride production was investigated. With a high oleic acid to acetone glycerol ratio (O/A, mol/mol), a high catalytic activity was observed under low water content in the reaction mixture. By the combination of high O/A ratio (>3) and removal of water which was produced during the reaction, the conversion degree was increased to almost 100%. With the O/A ratio of 3, the approximate half-life of the immobilized lipase and productivity of ester was estimated to be 20 days and 869 g product/g immobilized enzyme per 2 half-lives, respectively.     

Appearance of alpha-smooth muscle actin in human eye lens cells of anterior capsular cataract and in cultured bovine lens-forming cells

Using light and electron-microscopic immunolocalization techniques, and gel electrophoresis combined with immunoblotting, we have examined the expression of cytoskeletal proteins in normal human fetal, child and adult lenses, in human anterior capsular cataract and in bovine lens cells in vivo and in vitro. In this report, we focus our observations on the pattern of actin-isoform expression during normal and pathological situations in vivo and culture conditions. We have noted that cells of developing and mature human lenses as well as bovine lens cells in situ contain only beta- and gamma-actins. In contrast, alpha-smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle differentiation, was demonstrated in bovine lens cells at different times of culture. Moreover, the multilayered cells observed in the subcapsular zone of human anterior capsular cataract were characterized by the presence of alpha-sm actin. Thus, extensive changes in actin-isoform expression take place in lens cells growing in culture and may also occur during cataractogenesis. The biological meaning of the appearance of a marker of myoid differentiation in the ectodermally derived lens-forming cells is discussed.     

Oxidation of n-tetradecane by Candida parapsilosis KSh 21 adsorbed on different glass rings

Summary Living cells of Candida parapsilosis KSh 21 were immobilized by adsorption on different types of glass rings. The presence of n-tetradecane enhanced the cell adsorption especially on normal glass rings. The high adhesion of cellulose-coated glass rings and of sintered glass rings induced a quick adsorption of the cells. The quantity of 1-tetradecanol produced in the cultures of immobilized cells especially on SGR was higher than that of the free cells. Low numbers of free cells released in the immobilized cultures were observed. Better contact between the immobilized cells and oil droplets was noticed.     

Lipopolysaccharides of two strains of the phototrophic bacterium Rhodopseudomonas capsulata

The lipopolysaccharides of Rhodopseudomonas capsulata strains St. Louis (ATCC 23782) and Sp 11 both contain L-acofriose, rhamnose, glucose and glucosamine as the main sugar constituents. 2-Keto-3-deoxyoctonate and neuraminic acid were tentatively identified. The fatty acid spectrum found with both strains comprises 3-OH-C10 and C12:1 (ester-linked) and 3-oxo-C14 (amide-linked). Isolated lipid A from strain Sp 11 contains glucosamine, glucosamine-phosphate and the total of the fatty acids of the lipopolysaccharide. Methylation analysis of the degraded polysaccharide of this lipopolysaccharide shows L-acofriose in both terminal and 1 leads to 2 chain-linked positions in a 1:4 molar ratio. Rhamnose is exclusively chain-linked (1 leads to 2), glucose is both terminally and chain-linked (1 leads to 6) in a 1:1 molar ratio. The serological activity of the lipopolysaccharide of both the R. capsulata strains is low in antisera against living or heat-killed cells when tested by passive hemagglutination, Ouchterlony immunoprecipitation or gel-immunoelectrophoresis. No crossreaction was observed among the lipopolysaccharides of R. capsulata strains St. Louis, Sp 11 and 37b4 in immunoprecipitation. Lipopolysaccharide of strain Sp 11 was found to lack lethal toxicity in galactosamine-sensitized mice.     

Light and electronmicroscope study of one of the systems of centrifugal fibers found in the lamina of muscoid flies

Summary By combining the Golgi and the electronmicroscope techniques it has been possible to identify accurately the system of centrifugal fibers which arborizes in the lamina of muscoid flies forming the so-called nervous bags. Each of them originates from a single fiber entering the lamina at the site in which the second order and the long visual fibers leave it. This single fiber represents the peripheral portion of a T-shaped trunk stemming from a small neuronal body located in the external region of the medulla. The central branch terminates within the first synaptic field of this visual center.After entering the lamina the centrifugal fiber ramifies profusely and its branches can be seen climbing and synapsing on the surface of the photoreceptor axon endings. The synaptic loci show characteristic synaptic ribbons located within the nervous bag fibers. This fact suggests that direction of conduction is from the medulla to the lamina. This study has also revealed that the intramedullar terminals of the centrifugal fibers establish intimate contacts with one of the two second order fiber endings.This work was supported by Grant No. 618–67 (Mod No. 67–0618) of the Office of Aerospace Research, United States Air Force and by NIH grant NSO 866901.     

The fine structure of the visual system of lycosa (Araneae: Lycosidae)

Summary The optic lobes of spiders contain a well differentiated synaptic region — the lame medullaire — in which the photoreceptor axon terminals synapse with the axons of the second order neurons.Each photoreceptor terminal has a very irregular outline and contains a great number of vesicles. It sends out collateral branches which end either in contact with other photoreceptor terminals or in contact with second order fibers. The second order fibers lie deeply recessed within folds of the photoreceptor terminal membrane. Frequently branches of the second order fibers can be seen as independent elements within the photoreceptor terminals. The synaptic loci are characterized by the presence of synaptic ribbons surrounded by cumuli of vesicles. These synaptic loci are always located at the intermembrane cleft between adjacent second order fibers.Synaptic structures have been found also within the second order fibers which in such cases appear as pre-synaptic elements in regard to the photoreceptor terminals.Research sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force, under AFOSR Grant Nr. 618-64.     

Human arterial smooth muscle cells in culture: Inverse relationship between proliferation and expression of contractile proteins

Summary Human arterial smooth muscle cells (hASMC) from explants of the inner media of uterine arteries were studied in secondary culture. We had previously found that these cells depend on exogenous platelet-derived growth factor (PDGF) for proliferation in vitro. Deprivation of the serum mitogen(s) by culture in plasma-derived serum or bovine serum albumin (BSA) caused a true growth arrest that was reversible upon reexposure to the mitogen(s). When added to serum-containing medium, heparin caused a reversible growth arrest which could be competed for by increasing concentrations of serum. In the current study we used a set of smooth muscle-specific actin and myosin, antibodies to study the expression of contractile proteins in stress fibers under indirect immunofluorescence on hASMC in culture. Even in sparse culture, grwoth-arrested hASMC expressed stress fibers containing these actin and myosin epitopes. This was true irrespective of whether growth arrest was achieved by culture in media containing only BSA or a combination of heparin and whole blood serum. hASMC proliferating in whole blood serum in sparse culture did not express such strees fibers, as judged by immunofluorescent staining. This was true also for cells that were restimulated to proliferate in serum after a growth arrest. Utilizing a monoclonal antibody against a nuclear antigen expressed in proliferating human cells, we were able to demonstrate an inverse relationship between the expression of this antigen and the SMC-specific contractile proteins, respectively. Under these culture conditions, the reversible transition between defifferentiated and differentiated hASMC was almost complete and terminated about 1 wk after the change in culture condition. We conclude that hASMC in vitro respond, to exogenous PDGF by proliferation and dedifferetiation as a single population of cells. We also conclude that this modulation is reversible, because the cells become uniformly quiescent and differentiated when the mitogenic stimulus is blocked or removed. This study was supported by grants from the Swedish Medical Research Council (Project no. 4531 and 6816), the Swedish Association against Heart and Chest Diseases, the King Gustaf V and Queen Victoria Foundation, the National Institutes of Health, Bethesda, MD (grant HL 29873) and the Swedish National Board for Laboratory Animals.     

Fungal population in the atmosphere of Ismailia City

Fungal spore populations in the outdoor and indoor atmosphere of Ismailia have been studied during the period from March 1992 to May 1993. A total of 23 350 cfu and 73 species were recorded,Cladosporium cladosporioides, Aureobasidium pullulans andAspergillus flavus were the most abundant. The indoor and outdoor mycoflora showed marked quantitative and qualitative differences. In view of count, recorded species could be categorized into three groups as follows: (a) species showing higher counts in out- than indoor, (b) species showing the opposite trend i.e. lower counts in out-door than indoor, (c) species showing approximately equal counts in out- and indoor. Regarding seasonal periodicity, March and either September or October showed the highest count for both normal fungal flora (NFF) and opportunistic fungal flora (OFF). While January and July showed the lowest count of them both, May but not July was the lowest as for outdoor NFF.     

Factors affecting growth and urease production by Trichophyton spp.

Among Trichophyton spp. examined for urease production, T. rubrum was negative, whereas T. mentagrophytes appeared to be the most active species. Urease was not detected in cell-free culture fluids of the tested fungi. The endocellular urease of the test fungi was essentially constitutive. Moreover, addition of urea to the growth medium of these organisms markedly inhibited their mycelial biomass and ureolytic yield. Environmental factors showed variable effects on the test fungi and there was no correlation between mycelial growth and urease activity of these fungi.