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A phospholipase A2 with anticoagulant activity. I. Isolation from Vipera berus venom and properties.

An anticoagulant protein has been isolated by DEAE cellulose chromatography and gel filtration from the venom of the Vipera berus orientale (Eastern Europe). Purification has been completed by elution on carboxymethyl cellulose with continuous gradient at constant pH. The inhibitor of coagulation was separated from the other venom enzymes, e.g. procoagulant, fibrinogenolytic, aminoesterase and amino acid oxidase activities. It was also separated from other phospholipase components which were not related to the anticoagulant property. The inhibitor appeared as a simgle polypeptidic chain protein, formed by 119 amino acid residues, with a molecular weight of 13400 and an isoelectric point of 9.2. At low saline molarity, a monomer-trimer transition of this protein was observed. Both forms had the same amino acid composition. There were six disulfide bridges without free SH groups per phospholipase molecule. Deprived of any proteolytic activity, the clotting inhibitor displayed a high phospholipase activity in the presence of calcium. Activity did no appear with EDTA buffer deprived of cation. Finely dispersed micellar suspensions were found suitable for obtaining the highest phospholipase activity. High sodium cholate concentration or methanol/chloroform/ether solvent were effective without loss of enzymatic activity. As characteristis of phospholipase A2 (EC 3.1.1.4), the degradation products identified on thin-layer chromatography induced hemolysis of human erythrocytes. The apparent Km value 1.25 - 10(-3) M was determined on phosphatidylcholine isolated from ovolecithin. This purified berus inhibitor would be of value for investigating the involvement of phospholipids in the clotting mechanism.

Amino Acids

Properties of alkaline phosphatase of the halotolerant yeast Debaryomyces hansenii.

The molecular weight of a partially purified alkaline phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.1) from the halotolerant yeast Debaryomyces hansenii was estimated to 110,000 by gel filtration. The isoelectric point determined by electrofocusing was at approximately pH 4.4. The enzyme had a broad specificity against phosphomonoesters and also attacked some acid anhydrides. Arsenate, molybdate, and orthophosphate acted as competitive inhibitors. Various metal-binding agents inhibited enzyme activity. A zinc addition almost completely reversed the EDTA inhibition. Magnesium stimulated enzyme activity and was required for maintenance of activity at high concentrations of Na+. Increasing glycerol concentration increased the value of the Michaelis constant (Km) and decreased the maximum velocity (V). Solutions equimolar in KCl and NaCl stimulated enzyme activity by increasing V, whereas the Km was almost unaffected by salt concentration. Enzyme extracted from cells cultured at low salinity was indistinguishable from that of cells grown in the presence of 2.7 M NaCl with respect to several criteria.

Alkaline Phosphatase

Physiologically induced changes in intramembranous particle frequency in the axons of an osmoconforming bivalve.

Freeze-fractured axonal membrane surfaces from the connectives of Mytilus edulis show an increment in particle frequency of 52% (fixed tissues) or 68% (unfixed tissues) after long-term adaptation to low salinity. Particle size distribution was unaffected by osmotic adaptation, but was significantly different in fixed and unfixed material. The possibility that these structural changes reflect the known increase in sodium pump frequency in this osmoconforming tissue is considered.

Adenosine Triphosphatases

The effects of red blood cell suspending media on hemagglutination and the antiglobulin test.

Evaluation of the effects of four suspending media for test cells in antibody detection and identification is reported. The media under investigation are normal saline, low ionic strength salt solution, 22% bovine albumin and polymerized albumin. Hemagglutination at 37 C was enhanced in the test systems employing polymerized albumin. With shortened incubation times, the antiglobulin test was enhanced in tests against red blood cells suspended in the low ionic strength salt solution. When incubation times were extended to 30 minutes, all suspending media were apparently equally effective.

Antibodies

Prevalence of schistosomiasis among fishermen of Lake Maryut.

A survey was carried out to investigate the presence of Bilharziasis among the fishermen of the lake Maryut. Schistosoma mansoni is more prevalent, than S. haematobium among fishermen of lake Maryut. Biomphalaria alexandrina, snails were prevalent around the lake specially in places of low salinity, where fresh water discharges exist. Bulinus truncatus snails were not found during the time of the present survey and more frequent surveys are needed. There is an inverse relation between the number of snails and the salinity of the water. Since the salinity of the water is decreasing by time as a result of the increased discharge of agricultural and domestic waste into the lake, Bilharziasis infection may increase among the fishermen. This situation needs more attention from public health authorities in the area.

Adolescent

Use of low ionic strength saline for crossmatching and antibody screening.

A totally revised crossmatching and antibody screening procedure has been designed using low ionic strength saline as the suspending medium for red cells in the saline and enzyme phases as well as the antiglobulin test. The replacement of Pasteur pipettes with precision samplers for all serum and red cell dispensing has resulted in improvement in the reproducibility and standardisation of technique. The major advantages are improved sensitivity, shortened incubation time, and simplicity of technical performance.

Blood Grouping and Crossmatching

A comparison of a low ionic strength saline medium with routine methods for antibody detection.

Antibody detection studies were undertaken in order to compare a low ionic strength (LIS) medium with a conventional albumin-fortified isotonic medium. Tests were performed in parallel with both media at room temperature and at 37 C. A 30mM NaCl solution was used as the LIS medium and in this study this enhanced antibody reactions without causing nonspecific reactions. The LIS medium detected all of more than 50 Rh and more than 75 non-Rh antibodies after 15 minutes of incubation. Often 30 to 60 minutes of incubation were required to detect these antibodies by the routine method. Several antibodies that were detected with the LIS medium after 15 minutes of incubation were either undetected or had given a nonspecific pattern of activity after 60 minutes incubation in the routine medium. When an antibody was present, the LIS medium invariably gave stronger, more clear-cut results. It is concluded that the LIS medium is generally more sensitive than a conventional medium in detecting antibodies since such a medium will detect clinically significant antibodies after only 15 minutes incubation as well as detect antibodies missed by a conventional medium. An antibody detection system utilizing this medium has obvious applicability to a hospital transfusion service.

Coombs Test

Electrogenic Na+ transport in a crustacean coxal receptor.

1. The response of the coxal receptors of the crab Scylla serrata to step stretches consisted of a partial action potential, Va, followed by a steady-state depolarization, Vs. The input resistance of the fibre was reduced during Vs. 2. In the absence of stimulation, the dendrites of the receptors depolarized when external Na+ was substituted with choline or Li+, and when the external K+ concentration was increased or decreased. The dendrites also depolarized when ouabain was added to the saline. 3. The amplitude of both Va and Vs was dependent on external Na+. In cells which were depolarized by ouabain, the amplitude of Vs increased when the K+ concentration of the saline was reduced. 4. Vs was followed by a small, but long-lasting, after-potential which was depolarizing when the membrane potential was between -70 and -60 mV. In cells depolarized by ouabain or by low K+ saline, the after-potential became hyperpolarizing. 5. When trains of brief stretches (each 5 ms in duration) were used as stimuli, the cells responded with trains of Va responses. During this tetanic stimulation the cells hyperpolarized; cessation of the stimulus train was followed by a long-lasting hyperpolarization (PTH). 6. PTH was abolished in Li+ saline, in low K+ saline, and in the presence of ouabain. In control or in low K+ saline, PTH was not accompanied by a decrease in the input resistance of the fibres. 7. It is concluded that an electrogenic Na+ pump (or equivalent process) contributes a substantial fraction of the membrane potential of the unstimulated coxal receptors. Pump activity could be increased by Na+-loading the distal part of the cells with trains of Va responses. By contrast, during the steady-state response to stretch, the pump was not activated.

Animals

Teleost chloride cell. II. Autoradiographic localization of gill Na,K-ATPase in killifish Fundulus heteroclitus adapted to low and high salinity environments.

The specific binding and inhibitory action of (3H)ouabain were employed to localize transport Na,K-ATPase in the euryhaline teleost gill, a NaCl-transporting osmoregulatory tissue in which both enzyme activity and transepithelial transport vary with environmental salinity. In killifish fully adapted to 10%, 100%, or 200% seawater, the gills were internally perfused and externally irrigated in situ. After suitable internal or external exposure to (3H)ouabain, individual gill arches were excised for Na,K-ATPase assay, measurement of radiolabel binding, or quantitative high-resolution autoradiography. Internal exposure to 50 muM ouabain resulted in essentially complete enzyme inhibition, and binding paralleled the increases in enzyme activity at higher salinities; in contrast, external exposure gave minimal and erratic results consistent with leakage of external ouabain into interstitial fluid. (3H)Ouabain autoradiographs demonstrated that, irrespective of exposure or salinity, most of the gill binding was associated with chloride cell. These cells increased in size and number with salinity and, at the subcellular level, the distribution pattern for bound ouabain was always identical to that for the amplified basal-lateral (tubular system) membrane. The combined physiologicmorphologic results constitute final direct proof that chloride cells are the primary site of gill Na,K-ATPase. More important, they provide convincing evidence for unexpected increases in basal-lateral enzyme at higher salinities and thus raise a fundamental objection to the long-postulated role of the Na pump in secretory NaCl transport.

Adenosine Triphosphatases

A search for causes of polymorphism in Clithon oualaniensis (Lesson) (Gastropoda; Prosobranchia).

Western Clithon from India and Ceylon differs from eastern Clithon from the Malay Peninsula and Hong Kong as regards shell pattern and coloration (Grüneberg 1976, 1978). The western form lives in regions with high surface salinity whereas the eastern form lives in regions with low surface salinity. This situation may either reflect a causal relation, or it may be the result of a coincidence. The evidence presented in this paper speaks against a causal relation and suggests that other factors with a similar geographical distribution may be at work.

Animals

Building biofilms for saline hydrogenotrophic denitrification from contrasting origins: Convergent acclimation, divergent performance.

Hydrogenotrophic denitrification is promising for deep nitrogen removal from saline, low-C/N wastewaters, but rapid establishment of stable biofilms at high salinity remains challenging. Here, two saline-adapted inocula from two representative, functionally contrasting habitats-a functionally-diversified inoculum from mangrove sediment and a functionally-focused inoculum from seabed sediment-were acclimated in parallel H2-based membrane biofilm reactors at constant 3.5% salinity. The Diverse-derived biofilm required 80 d to reach steady state and achieved only partial denitrification with 61.1% nitrate removal and considerable nitrite accumulation. In contrast, the Focus-derived biofilm rapidly established complete denitrification within ∼40 d, which was maintained for >50 d, with effluent NOx- below 1 mg-N·L-1 and 98.7% nitrate removal. Microbiome analyses showed that identical operation promoted convergence in community structure and enriched similar community-level functional potentials. However, genome-resolved analysis revealed distinct source-dependent functional organization among dominant microbial populations. Complete denitrifiers co-encoding denitrifying, hydrogenotrophic, and autotrophic functions were preferentially enriched in the Focus-derived biofilm, whereas these functions remained partitioned among different dominant populations in the Diverse-derived biofilm, coinciding with less complete denitrification. These findings indicate that saline hydrogenotrophic denitrification performance depends not only on which functions are enriched at the community level, but also on how key functions become organized among microbial populations, providing a previously overlooked criterion for inoculum selection in saline biological nitrogen control.

Complete denitrification

A comparison of six procedures for compatibility testing.

Six procedures for compatibility testing were compared, using red blood cells sensitized in normal saline, albumin or low-ionic strength saline (LISS) combined with either broad spectrum or anti-IgG antiglobulin testing (AGT). Despite shortened incubation times, tests employing LISS were as sensitive as those with albumin and broad spectrum AGT and more sensitive than the other four combinations. No false positive results were found. LISS technique with broad spectrum AGT appears to be suitable and superior for routine antibody detection and compatibility tests.

Blood Grouping and Crossmatching

Osmotic fragility of leukaemic and normal lymphocytes.

The osmotic fragility of cord blood lymphocytes (CBLs), normal adult lymphocytes (NALs) and leukaemic cells was studied using hypotonic saline. Leukaemic cells were more resistant to hypotonic treatment than cord blood or adult lymphocytes. At low hypotonic saline concentrations (less than 0.2% NaCl), almost all of the NALs and CBLs were lysed after thirty minutes at 4 degrees C, whilst a large proportion of chronic lymphatic leukaemia cells remained intact. This phenomenon could conceivably be used to separate tumour cells from normal lymphoid cells.

Adult

Effect of ionic and non-ionic contrast media on morphology of human erythrocytes.

The effects of solutions of the ionic contrast media diatrizoate, iocarmate and metrizoate and the non-ionic metrizamide on red cell morphology were compared by interference contrast optics in vitro. All the media produced changes, in solutions both isotonic and hypertonic to blood. The changes increased with increasing volume ratio (contrast medium/blood). At low volume ratio the cells were transformed into crenated cells (echinocytes) in ionic solutions both hypertonic and isotonic to blood. At high volume ratio the hypertonic ionic media caused the red cells to become shrunken (desiccocytes), corresponding to the shrinkage caused by hypertonic saline. The low osmotic non-ionic metrizamide never produced desiccocytes but echinocytes also in high volume ratio. In solutions isotonic with blood metrizoate and metrizamide transformed more cells into echinocytes than the diatrizoate and iocarmate solutions.

Contrast Media

The effect of calcium and magnesium on the spontaneous release of transmitter at insect motor nerve terminals.

1. The effect of the extracellular calcium and magnesium concentrations and calcium ionophore, X-537A, on the frequency of miniature excitatory post-synaptic potentials (MEPSPs) was studied in cockroach leg muscle fibres. 2. The frequency of MEPSPs increased as the calcium concentration was increased from 0.1 to 10 mM. In the presence of 10 mM magnesium, however, raising the calcium concentration from 0.1 to 1 mM slightly depressed the frequency. In saline containing elevated potassium (20.8 mM), increasing the calcium concentration produced a much higher frequency than that in the normal potassium saline (10.8 mM) in the absence of magnesium. Raising the extracellular potassium concentration was without effect unless the bathing solution contained calcium. 3. The frequency of the miniature potentials was reduced as the magnesium concentration was raised from 0 to 10 mM, depending on the presence of calcium ions. On the contrary, a slightly increased frequency was observed in the low calcium saline as the magnesium concentration was raised from 1 to 10 mM. The reciprocal relationship between calcium and magnesium and the time course of the effect suggest that both ions act at the same surface sites in the presynaptic membrane. 4. X-537A elicited a transient increase in frequency followed by a fall of the frequency to a very low rate. Further application of the ionophore was without effect. The effect of X-537A on the spontaneous release of transmitter at the insect neuromuscular junction was comparable with that on the spontaneous acetylcholine release in vertebrate neuromuscular junctions.

Animals

Role of dialysis in the treatment of severe hypercalcemia: report of two cases successfully treated with hemodialysis and review of the literature.

The role of dialysis in the treatment of patients with severe hypercalcemia is uncertain. The fourteen previously reported cases of hypercalcemia treated with either peritoneal or hemodialysis have been reviewed. Two additional patients treated with hemodialysis are described in this report. Because the use of large volumes of intravenous fluids was contraindicated, each of the patients received a low calcium bath (0-1 mEq calcium per liter) hemodialysis for three and a half hours. After dialysis, the serum calcium fell to normal in both and remained normal thereafter with treatment of the underlying disease (multiple myeloma in one and vitamin D intoxication in the other). Hemodialysis can clear up to 682 mg of calcium per hour as compared to 124 mg per hour for peritoneal dialysis and 82 mg per hour with forced saline diuresis. Low calcium bath hemodialysis is indicated when the presence of renal and/or cardiac failure prevents the administration of large volumes of intravenous fluids to hypercalcemic patients.

Aged

The intra-nucleolar localization of amplified rDNA in Xenopus laevis oocytes.

A fluorescent Feulgen-stain was adapted in order to demonstrate DNA-containing structures inside the amplified nucleoli of Xenopus laevis. At all stages of oogenesis this method reveals granules or complex structures of DNA in each nucleolus. The micronucleoli which do not stain with this method and which do not reveal an internal structure in low molarity saline, unlike real nucleoli are considered as nucleolus-like bodies. The DNA-containing structures in the nucleoli can be composed of one or several granules, or they can be arranged in a linear, reticulated or circular form, independant of any correlation with the stage of oogenesis.

Animals