Effect of human defensins on the cytoplasmic Ca2+ content in platelets

The effect of the total fraction of human defensins (HNP-1, HNP-2, and HNP-3) on the cytoplasmic Ca²⁺ content ([Ca²⁺]_i) in the platelets of healthy donors was studied. At concentrations of 0.1–40 μg/ml and an incubation time of 10 min defensins have no effect on [Ca²⁺]_i in platelets labeled with Fura-2AM. However, at higher concentrations (100 μg/ml) they increased platelet [Ca²⁺]_i. In addition, defensins (40 μg/ml) inhibited the Ca²⁺ increase in platelets induced by thrombin, adenosine diphosphate, and the lipopolysaccharide ofS. typhimurium endotoxin. The most pronounced inhibitory effect was observed in a suspension of thrombin-stimulated platelets. It is shown that the effect of human defensins on the functional activity of platelets is due to the alterations in the intracellular Ca²⁺. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 600–603, December, 1994     

Polyunsaturated phosphatidylcholine micelle-induced decrease of atherogenicity of the serumin vitro

It is shown that polyunsaturated phosphatidylcholine administered in micelles stabilized by a plant-derived glycoside prevents the accumulation of cholesterol by cells incubated in atherogenic serum and, moreover, in certain cases causes a 1.4–1.5-fold drop of intracellular cholesterol as compared to control cells. The optimum antiatherogenic effect was achieved when using a micelle concentration of 100–200 μg/ml and an incubation time of at least 4 hours. The antiatherogenic effect was analogous to the effect of high density serum lipoproteins. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5 pp. 497–501, May, 1995 Presented by Yu. M. Lopukhin, Member of the Russian Academy of Medical Sciences     

On the mechanism of insulinotropic action of hepoxylins: Evidence of a direct,glucose-independent effect of hepoxylins B3 on insulin secretion

The effects of lipoxygenase metabolites of arachidonic acid, hepoxylin B₃ epimers, on insulin secretion by a culture of isolated islet cells were studied. The effect was assessed at hepoxylin B₃ concentrations of 0.2 to 5.0 μM and different glucose concentrations in the culture medium. Both hepoxylin B₃ epimers were shown to boost the stimulating effect of glucose on insulin secretion. This effect manifests itself at glucose concentrations of 5.5 and 11 mM and disappears at an above normal glucose content in the medium (20 mM). The capacity of hepoxylin B₃ to stimulate the secretion of insulin by a culture of islet cells in a glucose-free medium has also been demonstrated. This direct, not glucose-mediated, insulinotropic effect may serve as proof that the hepoxylins belong to the category of intracellular messengers. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 10, pp. 404–406, October, 1995 Presented by I. G. Akmaev, Member of the Russian Academy of Medical Sciences     

Inhibition of platelet aggregation by monoclonal antibodies against glycoprotein IIb–IIIa complex

Monoclonal antibodies CRC64 are obtained against Ca²⁺-dependent glycoprotein IIb–IIIa complex of the platelet membrane which possess the ability to inhibit completely fibrinogen-dependent platelet aggregation. CRC64 is directed against the epitope formed by the glycoprotein IIb–IIIa complex and does not interact with proteins isolated after platelets are treated with ethylenediamine tetraacetate. Complete, reproducible blockade of platelet aggregation caused by 5 μM adenosine diphosphate is noted in an MCA concentration of 3 μg/ml, while in the case of a stronger inductor, namely 1 U/ml thrombin, platelet aggregation is inhibited in a concentration of 5 μg/ml. F(ab′)₂ fragments are also able to inhibit platelet aggregation completely and are usually effective in concentrations lower than native monoclonal antibodies. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 402–405, October, 1994 Presented by V. N. Smirnov, Member of the Russian Academy of Medical Sciences     

Impact of plasmin and its complexes with α2-macroglobulin or α2-antiplasmin on the proliferative activity of human lymphocyteson the proliferative activity of human lymphocytes

It is shown that plasmin in doses of 0.1, 1, or 10 μg/ml did not influence significantly phytohemagglutinin-induced proliferation of mononuclear lymphocytes in a 3-day culture with these cells. Their proliferative response to pokeweed mitogen was stimulated by plasmin in the dose of 10 μg/ml only. Biogenic complexes of plasmin with α₂-macroglobulin or α₂-antiplasmin induced a moderate reduction of spontaneous proliferation after 3 days of culture, and so did plasmin after 5 days; α₂-macroglobulin induced a dose-dependent comitogenic effect with phytohemagglutinin and pokeweed mitogen, while α₂-antiplasmin induced a dose-independent comitogenic effect with pokeweed mitogen. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 304–305, September, 1994 Presented by V. A. Trufakin, Member of the Russian Academy of Medical Sciences     

Formation of colonies of clonogenic stromal precursors in bone marrow and splenic cell cultures in the presence of streptococcal antigens in the culture medium

The presence of streptococcal M protein and A polysaccharide in culture medium is shown to have an inhibitory effect on the growth of clonogenic stromal precursors in cultures of healthy murine bone marrow and of healthy guinea pig bone marrow and spleen. The efficacy of colony formation dropped 1.5- to 2-fold in the presence of antigens in a concentration of 25 μg/ml in the medium. The inhibitory effect was absent if antigens were added to adhesive cell cultures. The addition of antigens to cultures originating from animals immunized with streptococcus resulted in inhibition of the efficacy of colony formation in complete cultures and in cultures of adhesive cells. The presence of streptococcal antigens in guinea pig stromal fibroblast cultures of different strains did not affect their growth or colony formation. These data indicate that the effects of streptococcal antigens appear to be aimed at the stromal cells not directly, but rather via another cellular category in the bone marrow and splenic cell cultures, probably lymphocytes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 11, pp. 489–492, November, 1994     

Circulating serum interferon andits effect on the activity of human natural killer cells

The interferon content in the plasma of 6 healthy donors and 10 patients with multiple sclerosis and the effect of an 1-h treatment of mononuclear cells with autologous plasma on their natural killer activity are studiedin vitro using³H-uridine-labeled (3 μCi/ml) human erythromyeloleukosis cells K-562. The serum interferon content in healthy donors is 2.3±0.82 IU/ml, whereas that in patients is higher: 5.2±0.8 IU/ml. Autologous plasma does not affect the activity of natural killer cellsin vitro, whereas it increases the cytotoxicity of mononuclear cells obtained from patients with multiple sclerosis by 35–64%. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 619–622, December, 1994 Presented by S. V. Prozorovskii, Member of the Russian Academy of Medical Sciences     

Mechanism of action of the new cardiotonic suphan on calcium exchange in cardiomyocytes

Effects of suphan, a new cardiotonic agent containing succinyl tryptophan, on the entry of Ca²⁺ into rat cardiomyocytes, its intracellular compartmentalization, and its exit from these cells were evaluatedin vitro. It was found that the recorded sulfan-induced rise of intracellular calcium was due to Ca²⁺ entering the cell via L-type calcium channels, and that a reversible reduction of its concentration in the sarcoplasm occurred through its accumulation in the sarcoplasmic reticulum and was blocked by the specific Ca²⁺-ATPase inhibitor thapsigargin (10 μM). Suphan did not alter the activity of Na⁺/Ca²⁺ exchange in a concentration range of 5–150 μg/ml. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 7, pp. 57–59, July, 1996     

The anti-amoebic activity of some medicinal plants used by AIDS patients in southern Thailand

The anti-amoebic activities of chloroform, methanol and water extracts from 12 Thai medicinal plants (39 extracts) commonly used by AIDS patients in southern Thailand were screened, at a concentration of 1,000 μg/ml, against Entamoeba histolytica strain HTH-56:MUTM and strain HM1:IMSS growing in vitro. The extracts were incubated with 2×10⁵ E. histolytica trophozoites/ml of medium at 37°C under anaerobic conditions for 24 h. The cultures were examined with an inverted microscope and scored (1–4) according to the appearance and numbers of the trophozoites. The extracts that caused inhibition were selected and retested using the same conditions but with concentrations that ranged from 31.25 to 1,000 μg/ml using E. histolytica strain HM1:IMSS, and the IC₅₀ values for each extract were calculated. The chloroform extracts from Alpinia galanga (IC₅₀ 55.2 μg/ml), Barleria lupulina (IC₅₀ 78.5 μg/ml), Boesenbergia pandurata (IC₅₀ 45.8 μg/ml), Piper betle (IC₅₀ 91.1 μg/ml) and Piper chaba (IC₅₀ 71.4 μg/ml) and the methanol extract from B. pandurata (IC₅₀ 57.6 μg/ml) were all classified as “active”, i.e. with an IC₅₀ of less than 100 μg/ml, whereas those from Murraya paniculata (IC₅₀ 116.5 μg/ml) and Zingiber zerumbet (IC₅₀ 196.9 μg/ml) were classified as being “moderately active”. The IC₅₀ of a standard drug, metronidazole, was 1.1 μg/ml.     

Effect of amiridine and tacrine on the functional degeneration of the isolated neuron

Amiridine and tacrine are found to have a concentration-dependent effect on the spontaneous activity of an isolated neuron from crawfish. Amiridine in a concentration of 1 μM reliably prolongs the lifetime of the neuron, whereas lower concentrations are inactive and a high concentration (10 μM) reduces spontaneous activity. Tacrine is unable to prolong the lifetime of the neuron. It is suggested that, unlike tacrine, the therapeutic effect of amiridine stems from its ability to prolong neuronal functioning. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 52–54, January, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Rapid decrease of free vancomycin in dense staphylococcal cultures

Bacterial numbers in broth cultures were determined by bioluminescence assay of intracellular bacterial ATP. Broth MICs for strains of Staphylococcus epidermidis (ATCC 14990 and 35984) and Staphylococcus aureus (ATCC 25923, 29213 and 6538) were determined for cultures with different inocula (10⁵–10⁸ bacteria/ml) after 24 h of incubation in supplemented Mueller–Hinton broth containing vancomycin. All of the tested strains except one were susceptible to methicillin, and all of the strains were susceptible to vancomycin. Free vancomycin concentrations in the broth cultures of all strains were determined with an agar well bioassay after 24 h of incubation. Free vancomycin concentrations and bacterial numbers of ATCC 35984 and ATCC 29213 were also determined after 0.5, 2, 4, and 8 h. In a low inoculum (10⁵ bacteria/ml), the broth MICs were 1–4 μg/ml. In a high inoculum (∼10⁸ bacteria/ml), the broth MICs increased two- to fourfold to 4–8 μg/ml. In dense inocula (∼10⁹–10¹⁰ bacteria/ml), the concentrations of free vancomycin in the broth were reduced, in most cases below the detection limit of the bioassay (≤0.5 μg/ml). This reduction of free vancomycin was fast, occurring in initially dense inocula in less than 30 min. No emergence of resistance was seen. These results show a rapid reduction of free vancomycin in the broth and a simultaneous increase in broth MICs in high inocula, without development of resistance. This indicates that the dosing regimen of vancomycin is of particular importance in staphylococcal infections with dense inocula, e.g. infective endocarditis.     

“Medium molecules” as nonspecific regulators of phagocytic activity

Three identical oligopeptide-containing fractions of so-called “medium molecules”, isolated by sequential ultrafiltration and gel chromatography from the blood of 8 intact dogs and 15 dogs with an extensive thermal burn, were examined for their impact on phagocytic cells (neutrophil granulocytes and macrophages) in relation to the molecular-weight distribution of the molecules. The relatively high-polymer fractions of medium molecules, unlike oligomeric fractions, stimulated the phagocytic activity of these cells. Because of their increased polymerism, the fractions of medium molecules from dogs with thermal trauma stimulated phagocytosis to a greater extent than did those from intact animals. Translatedfrom Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, pp. 159–162, February, 1995 Presented by V. A. Trufakin, Member of the Russian Academy of Medical Sciences     

The Effect of Anti-Tuftsin Antibody on the Phagocytosis of Bacteria by Human Neutrophils

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide which stimulates most known functions of the polymorphonuclear and mononuclear phagocytic cell lines. Although tuftsin is a well characterized bioactive peptide, the exact physiological role tuftsin plays remains unclear. Specific mouse anti-tuftsin antiserum generated in our laboratory, is now available for phagocytosis inhibition studies. Monolayers of human neutrophils were prepared on glass coverslips from a few drops of finger prick blood obtained from a single healthy donor. The monolayers were treated with and without mouse anti-tuftsin antiserum at dilutions of 1:1000 or 1:2000. Exogenous tuftsin (1 μg/ml) was also added with and without antibody. Treated and untreated neutrophils were subsequently incubated with unopsonized Staphylococcus aureus The proportion of cells accomplishing phagocytosis (phagocytic index) and the number of bacteria engulfed per cell (avidity index) were recorded. The results showed that exogenous tuftsin increased phagocytosis while the addition of mouse anti-tuftsin antiserum at a 1:1000 dilution inhibited phagocytosis both with and without exogenous tuftsin. This effect was diminished by the antiserum at the 1:2000 dilution. This study reaffirms that tuftsin plays an important physiological role in phagocytosis.     

Effect of chlorophos (dipterex,trichlorphon) on high-threshold potassium and calcium channels of the neuronal membrane

The effect of chlorophos (dipterex, trichlorphon) on high-threshold potassium and calcium currents is studied on isolated snail neurons using the patch-clamp technique. Chlorophos (10–1000 μmol/liter) is found to reversibly lower the peak amplitude of a high-threshold potassium current by 30% on average and exerts two independent effects on a high-threshold calcium current: reversible lowering of the peak amplitude by 35% on average and, in 30% of cases, reversible inhibition of its activation, inactivation, and deactivation. this effect is abolished by adding diltiazem (a calcium channel antagonist) in a concentration of 100 μmol/liter to the medium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 59–62, January, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Stimulation of proliferative activity of human natural killers (CD16+CD56+ cells) by recombinant interleukin-3in vitro

The proliferative activity of human natural killers (CD16⁺CD56⁺ cells) in the presence of 100 and 1000 IU/ml human recombinant interleukin-3 is investigatedin vitro. It is shown that recombinant interleukin-3 reliably enhances natural killer proliferation, causing a 9–15.2-fold increase of³H-thymidine uptake by CD16⁺CD56⁺ cells both in complete culture medium and in conditioned medium. The effect of the factor is 3.9–6.4 and 3.6–8.9-fold more potent than that of recombinant interleukin-2 and granulocyte-macrophage colony-stimulating factor, respectively, in the same doses. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp. 409–412, April, 1995 Presented by S. V. Prozorovskii, Member of the Russian Academy of Medical Sciences     

The use of a nonopiate leu-enkephalin analog and of hydra peptide morphogen for the correction of proliferation disturbances in tracheal epithelium and of LPO processes in lungs of newborn rats exposed to prenatal hypoxia

Newborn rats were born of females exposed to high-altitude hypoxia. Pregnant females were injected i.p. either nonopiate leu-enkephalin analog or hydra peptide morphogen 10 μg/kg 30 min prior to being placed in a pressure chamber. Prenatal hypoxia causes the inhibition of the proliferative processes in tracheal epithelium and activation of lipid peroxidation (LPO) in lungs of newborn rats. The administration of nonopiate leu-enkephalin analog prevents the development of posthypoxic alterations in newborn rats. The administration of hydra peptide morphogen inhibits the proliferation of tracheal epithelium and lowers the activity of the antioxidant defense of the lungs in newborn rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 5, pp. 535–537, May, 1994 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Impact of 13(S)-HPODE,a lipoxygenase product of linoleic acid,on calcium transport and Na,K-ATPase activity in the myocardial sarcolemma

In thisin vitro study using a purified sarcolemmic fraction of guinea pig myocardium, the 13(S)-hydroperoxide of linoleic acid (13-HPODE) increased in a dose-dependent manner the permeability of myocardial sarcolemma to Ca ions in concentrations above 10 μmol/liter, stimulated Na/Ca exchange there in concentrations from 0.1 to 10 μmol/liter, and exerted a digitalis-like action on sarcolemmic Na,K-ATPase in concentrations between 0.1 and 100 μmol/liter (IC₅₀=20 μmol/liter). The results indicate that the linoleic acid hydroperoxide may be an effective modulator of sarcolemmic Ca²⁺ transport and of membrane-bound enzymes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 255–257, September, 1995 Presented by D. F. Chebotarev, Member of the Russian Academy of Medical Sciences     

Comparative studies of the anti-leishmanial activity of three <Emphasis Type="Italic">Crotalus durissus</Emphasis> ssp. venoms

In this study, we compared the anti-leishmanial activity of three crotalic venoms (Crotalus durissus terrificus–Cdt, Crotalus durissus cascavella–Cdca, and Crotalus durissus collilineatus–Cdcol). Different concentrations of each venom incubated with Leishmania (Leishmania) amazonensis promastigotes were used. Cdt venom exhibited a higher anti-leishmanial activity (Inhibitory concentration-IC50-value of 4.70 ± 1.72 μg/ml) in comparison with that of Cdca venom (IC50 value of 9.41 ± 1.21 μg/ml), while Cdcol venom increased parasite numbers in 50% at a concentration of 44.30 ± 2.18 μg/ml. In addition, this venom showed a low anti-leishmanial activity in higher concentrations (IC50 value of 281.00 ± 9.50 μg/ml). The main fractions of Cdca venom were isolated and assayed under similar conditions used for assessing crude venom. The most active fractions were gyroxin and crotamine that had IC50 values of 3.80 ± 0.52 μg/ml and 19.95 ± 4.21 μg/ml, respectively. Convulxin also inhibited parasite growth rate, although this effect was not dose-dependent. Crotoxin was the least effective fraction with an IC50 value of 99.80 ± 2.21 μg/ml. None of the protein fractions presented cytotoxic effects against J774 cells in culture. In vivo assays using BALB/c mice revealed that crotoxin and crotamine were the main toxic fractions. In conclusion, C. durissus cascavella venom has three main fractions with anti-leishmanial activity. These results open new possibilities to find proteins that might be used as possible agents against cutaneous leishmaniasis.     

Prophylactic and corrective action of the polyethylene oxide polyox WSR-301 in rats with experimental lipoidosis

Two once-weekly intravenous injections of the polyethylene oxide Polyox WSR-301 (yielding a blood concentration of the order of 5×10⁻⁶ g/ml) led to a 38% decrease in the area occupied by sudanophilic lesions in the aortic arch of rats fed an atherogenic diet for two weeks. Perfusion under constant pressure of the formalin-fixed vascular system in the posterior part of the body with physiological saline and then with polyethylene oxide (10⁻⁵ g/ml) was without effect in normal rats and in those with mild lipoidosis, but reduced hydrodynamic vascular resistance by 9–14.5% in rats with pronounced lipoidosis. Intravenous injection of polyethylene oxide into anesthetized rats with pronounced lipoidosis in doses that were subthreshold for normal rats (blood concentrations of the polymer were of the order of 10⁻⁷ g/ml) caused a 20% decrease in the total peripheral resistance to blood flow, with a 17–20% rise of the blood flow rate in the carotid artery. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 587–589, June, 1995 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Antileishmanial potential of a marine sponge, <Emphasis Type="Italic">Haliclona exigua</Emphasis> (Kirkpatrick) against experimental visceral leishmaniasis

In this study, we are reporting antileishmanial activity of a marine sponge Haliclona exigua, belonging to phylum Porifera. The crude methanol extract and its three fractions were tested both in vitro and in vivo. The crude extract exerted almost complete inhibition of promastigotes at 50 μg/ml and 76.4 ± 6.5% inhibition of intracellular amastigotes at 100 μg/ml concentration with IC₅₀ values of 18.6 μg/ml and 47.2 μg/ml, respectively. When administered to Leishmania donovani infected hamsters at a dose of 500 mg/kg × 5, p.o., it resulted in 72.2 ± 10.4% inhibition of intracellular amastigotes. At a lower dose (250 mg/kg), it exhibited 43.9 ± 5.1% inhibition. Among the fractions, highest antileishmanial activity both in vitro (>90%) and in vivo (60.9 ± 18.3%) was observed in n-butanol (soluble) fraction with IC₅₀ values of 8.2 μg/ml and 31.2 μg/ml against promastigotes and intracellular amastigotes, respectively. Hexane fraction also showed comparatively good activity against both the stages of parasites in vitro but was moderately active in leishmania-infected hamsters. Chloroform fraction resulted in 45 ± 10.2% inhibition in vivo at a dose of 500 mg/kg × 5, p.o., whereas it was inactive in vitro. n-Butanol (insoluble) fraction was inactive both in vitro and in vivo. Araguspongin C, an alkaloid isolated from n-butanol (soluble) fraction exhibited moderate inhibition of promastigotes and intracellular amastigotes at 100 μg/ml but showed weak antileishmanial action in vivo. Our findings indicate that this marine sponge has the potential to provide new lead toward development of an effective antileishmanial agent and, hence, calls for more exhaustive studies for exploiting the vast world of marine resources to combat the scourge of several parasitic diseases.