Effect of colloid gold on physiologic-biochemical processes in Escherichia coli 1257

The influence of colloid gold on the growth processes, ATP-ase activity and extrusion of protons in Escherichia coli 1257 was studied. The particles of colloid gold exert nonmonotonous influence on these processes with different direction is such a way that small concentration of this metal (5 x 10(-7)-5 x 10(-6) mg/ml) exert stimulative effect, while higher concentrations of colloid gold result in the suppression of biological activity of the bacterial cells. The discovered peculiarities of colloid gold influence of E. coli strain may be determined by specificity of contact interaction of metal particles with the surface of bacterial cells.     

Improved use of organic phosphate by Skeletonema costatum through regulation of Zn2 + concentrations

The maximum growth rate (1.4-2 x 10(5) cells ml(-1) d(-1)), cell final yields (2.6-5.2 x 10(5) cells ml(-1)) and extracellular alkaline phosphatase activity (2.4-10.6 microg phosphate released ml(-1) h(-1)) of the red tide alga, Skeletonema costatum, increased when Zn2+ was increased from 0 to 24 pM, but decreased with 66 pM Zn2+ in growth medium with glycerophosphate as the sole phosphorus source. Extracellular carbonic anhydrase activity and the affinity for HCO3- and CO2 uptake increased when Zn2+ was increased from 0 to 12 pM, but then decreased at higher concentrations. The results suggested that utilization of organic phosphate required more Zn2+ than the uptake of inorganic carbon did, while utilization of dissolved inorganic carbon by Skeletonema costatum was very sensitive to Zn2+ concentration variations.     

Direct electrochemistry of horseradish peroxidase immobilized on a colloid/cysteamine-modified gold electrode

Direct electron transfer of immobilized horseradish peroxidase on gold colloid and its application as a biosensor were investigated by using electrochemical methods. The Au colloids were associated with a cysteamine monolayer on the gold electrode surface. A pair of redox peaks attributed to the direct redox reaction of horseradish peroxidase (HRP) were observed at the HRP/Au colloid/cysteamine-modified electrode in 0.1 M phosphate buffer (pH 7.0). The surface coverage of HRP immobilized on Au colloid was about 7.6 x 10(-10) mol/cm(2). The sensor displayed an excellent electrocatalytic response to the reduction of H(2)O(2) without the aid of an electron mediator. The calibration range of H(2)O(2) was 1. 4 microM to 9.2 mM with good linear relation from 1.4 microM to 2.8 mM. A detection limit of 0.58 microM was estimated at a signal-to-noise ratio of 3. The sensor showed good reproducibility for the determination of H(2)O(2). The variation coefficients were 3. 1 and 3.9% (n = 10) at 46 microM and 2.8 mM H(2)O(2), respectively. The response showed a Michaelis-Menten behavior at higher H(2)O(2) concentrations. The K(app)(M) value for the H(2)O(2) sensor was found to be 2.3 mM.     

Inhibition of carbonic anhydrase in the gills of two euryhaline crabs,Callinectes sapidus and Carcinus maenas,by heavy metals

Two subcellular fractions of gill tissue, cytoplasm and basolateral membranes, from two species of euryhaline decapod crustaceans, Callinectes sapidus and Carcinus maenas, acclimated to low salinity, were isolated via differential centrifugation. Carbonic anhydrase activity from both fractions was titrated against a variety of heavy metals in vitro. The metals Ag(+), Cd(2+), Cu(2+) and Zn(+) showed inhibitory action against the enzyme. Ki values for these metals against cytoplasmic CA from C. sapidus were in the range of 0.05-0.5 microM (for Ag(+), Cd(2+) and Cu(2+)) and 2-6 microM for Zn(+), some of the highest sensitivities reported for CA from an aquatic organism. The Ki values for these same metals were approximately 2-3 orders of magnitude higher for cytoplasmic CA from C. maenas, indicating that there are significant differences in heavy metal sensitivity in branchial CA from the two species, and that C. maenas possesses a metal-resistant CA isoform. It required concentrations of metals in the millimolar range, however, to inhibit CA activity from the membrane fraction of the gill of both species. There were no effects on either mortality or on hemolymph osmotic and ionic concentrations in C. maenas that were exposed to 10 microM Cd or Zn(+) at 32 per thousand salinity and subsequently transferred to 10 per thousand. The presence of a metal-resistant CA isoform in the gills of C. maenas suggests that this species would not be restricted from its normal estuarine environment by heavy metal pollution.     

Short peptide receptor mimics for atherosclerosis risk assessment of LDL

Short peptides sequences were selected that showed binding selectivity towards healthy or oxidised (unhealthy) low density lipoprotein (LDL), respectively. These were investigated for application in atherosclerosis risk monitoring. Comparison was also made with the LDL receptor ligand repeat peptide (LR5). The peptides were immobilised on a gold surface plasmon resonance surface and LDL binding detected as a shift in the resonance. 3.7x10(7) (+/-5.6x10(6)) LDL/mm(2)/microg/ml solution LDL were bound on GlySerAspGlu-OH and 6.8x10(7) (+/-9.2x10(6)) LDL/mm(2)/microg/ml on GlyCystineSerAspGlu, compared with approximately 10(8) LDL/mm(2)/microg/ml on LR5. In this first group, binding of LDL decreased with oxidation level and a good correlation was found between LDL binding and residual amino groups on the apoprotein of the LDL following oxidation, or the change in relative electrophoretic mobility (REM) of LDL. The decrease in binding was 1.1x10(7) LDL particles/mm(2) per% oxidation for GlySerAspGlu-OH, 1.8x10(7) LDL particles/mm(2) per% oxidation for GlyCystineSerAspGlu and 2.4x10(7) LDL particles/mm(2) per% oxidation for LR5. A second group of three peptides were also selected showing increased binding with LDL oxidation: GlyCystineCysCys (1.5x10(7) LDL/mm(2) per microg/ml), GlyLysLysCys-SH (10(7) LDL/mm(2) per microg/ml) and GlyLysLys-OH (5.6x10(7) LDL/mm(2) per microg/ml). The latter gave a linear increase in LDL binding with oxidation level (1.2x10(7) LDL particles/mm(2) per% oxidation). LDL concentration is around 2-3 mg/ml in plasma compared with the low detection levels with this method (1-10 microg/ml), allowing a strategy to be developed requiring the minimum sample volume and diluting with physiological buffer prior to assay. By using a comparative reading between LDL adsorption on surfaces from the first and second group of peptides (e.g. GlyCystineSerAspGlu and GlyLysLys-OH, respectively), LDL oxidation could be determined without knowledge of LDL concentration. Higher binding was seen on GlyCystineSerAspGlu than GlyLysLys-OH below 30% LDL oxidation, whereas above 30% oxidation the binding on the latter surface was greater. Simple correlation of this form could provide good tests for atherosclerosis risk.     

Probiotic effects of beta-glucuronidase on the peach-potato aphid Myzus persicae (Aphididae)

beta-glucuronidase (GUS) is a reporter protein commonly expressed in transgenic plants allowing the visualization of the transformed individuals. In our recent work, we showed that consumption of transformed potato plants expressing this GUS enzyme improves performance of the phloem feeding aphid Myzus persicae. Those results led us to the conclusion that the expression of GUS in potato plants might be responsible for the probiotic effect measured in feeding aphids. In the present paper, artificial diets were used to provide active GUS (10 and 500 microg ml(-1)), inactivated heated GUS (500 microg ml(-1)), glucuronic acid (10, 100 and 500 microg ml(-1)), and bovine serum albumin (500 microg ml(-1)) to M. persicae. Our results reveal that these chemicals provided as food intake might influence the biological parameters of this aphid. Experiments showed a probiotic effect of 500 microg ml(-1) GUS diet, resulting in reduced larval mortality, and increased adult reproduction period and fecundity, which led to an increased population growth potential (r(m)=0.17+/-0.01 versus r(m)=0.12+/-0.03 for aphids fed on control diet). A lower amount of added GUS led to fewer variations, biological parameters being only slightly altered (r(m)=0.14+/-0.03). Statistically similar alterations of the biological parameters were obtained when comparing aphids fed on the diet added with inactivated GUS or the non-structural bovine serum albumin protein (r(m)=0.15+/-0.02 and 0.14+/-0.03, respectively). Feeding assays conducted with glucuronic acid supplemented diets enhanced longevity and nymph production of the adult aphids and reduced larval mortality, resulting in r(m)=0.15+/-0.02 for the highest dose (500 microg ml(-1)). Although 100 microg ml(-1) glucuronate diet did not induce any effect on M. persicae (r(m)=0.12+/-0.03), aphids fed on 10 microg ml(-1) glucuronate diet exhibited unexpected reduced demographic parameters (r(m)=0.10+/-0.03). Immuno-histological analysis showed GUS labeling along the whole digestive epithelium of adults and in various tissues including embryos and bacteriocytes. These results suggest that GUS crosses through the digestive tract. Western blots performed with protein extracts of transformed potato plants expressing the gus gene showed a unique band of molecular weight 76 kDa. On the contrary, in extracts from aphids fed on transgenic potato plants or bred on GUS 500 microg ml(-1) artificial diet, several proteins of lower molecular weight were hybridized, revealing proteolysis of ingested GUS. It is concluded that GUS protein, and more precisely GUS activity, is responsible for the probiotic effects on aphid feeding. The possible pathways of induction of such physiological alterations by GUS are discussed.     

Involvement of nitric oxide in endothelium-dependent arterial relaxation by leptin

Leptin is a polypeptide, mainly produced in white adipose tissue, and increases sympathetic nerve activity. A few studies investigated leptin's effect on peripheral vessels. We examined the vasorelaxant effects of human leptin on rat arteries. Arterial rings were precontracted with 1 x 10(-6) mol/l of phenylephrine, and leptin was superfused. Leptin relaxed phenylephrine-precontracted arterial rings in a dose-dependent manner. ED50 was calculated to 8.4 microg/ml. Removal of endothelium abolished the effects of leptin. Indomethacin (1 x 10(-5) mol/l) did not affect the vasorelaxation by leptin, whereas 1 x 10(-4) mol/l of N(omega)-nitro-L-arginine methyl ester (L-NAME) completely suppressed it. The inhibition was antagonized by 1 x 10(-4) mol/l of L-arginine. Leptin normally relaxed arterial rings during superfusion of K channel blockers, including 3 x 10(-5) mol/l of glibenclamide, 1 x 10(-6) of mol/l apamin, and 5 x 10(-7) mol/l of charybdotoxin. Low Cl(-) solution (8. 3 mmol/l) inhibited leptin-induced relaxation, but endothelium-independent vasodilatation by nitroprusside was not impaired at low Cl(-) solution. These results suggest that arterial relaxation by leptin is mediated by nitric oxide released from endothelium, and Cl(-) plays an important role in leptin-induced nitric oxide release.     

Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b

Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.     

银离子抗性细菌质粒的分离与鉴定

通过对不同化工厂废水处理池的活性污泥进行富集、不同浓度银离子驯化后,分离得到30株银离子抗性细菌,最大硝酸银耐受量可达80 mg·ml^-1.对这些细菌进行质粒抽提与鉴定,质粒检出率为76.67％.40 mmol·L^-1的苯甲酸钠对HAg4细菌质粒的消除率可达98.75％;而350 μg· ml^-1的吖啶橙对HAg4细菌质粒的消除率只有77.78％.细菌质粒与银离子抗性密切相关.     

Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b

Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.     

Release of beta-hexosaminidase after administration of different agents affecting the reticuloendothelial system. An experimental study in rats

Plasma levels of a lysosomal enzyme, beta-hexosaminidase (beta-N-acetylglucosaminidase, EC 3.2.1.30) were studied in Wistar rats after administration of 99mTc -sulfur colloid, 198Au colloid, gelatine (Haemaccel), alcohol, methylpalmitate and zymosan. The activity of beta-hexosaminidase was increased 10, 30 and 60 min after the zymosan injection. After 24 and 48 h, enzyme levels had returned to those at outset. The transient release of beta-hexosaminidase probably occurred only during the phagocytosis of zymosan which was evaluated by histological examination of lung, liver and spleen. After the injection of all other agents tested, no significant aberration of beta-hexosaminidase levels was seen. Activity distribution of the radio-labeled colloids revealed differences in organ uptake which were attributed to a difference in colloid particle size. Although the colloids tested have been used extensively for determination of reticuloendothelial function and histological studies suggest phagocytosis of the particles, their administration did not affect plasma beta-hexosaminidase levels. Since lysosomal enzymes are cleared from the blood predominantly by liver macrophages, the primary location of particle phagocytosis may explain the present findings.     

Quantitative analysis of the elemental composition and the mass of bacterial polyphosphate bodies using STEM EDX

The quantitative analysis of laboratory grown organisms (Plectonema boryanum and Staphylococcus aureus) revealed that a typical in vivo polyphosphate body (PPB) contains O (4.3 x 10(-8) microg), C (1.2 x 10(-8) microg), P (6.7 x 10(-9) microg), Mg (1.3 x 10(-9) microg), Ca (6.7 x 10(-10) microg), K (6.7 x 10(-10) microg), Fe (6.0 x 10(-10) microg), S (5.4 x 10(-10) microg) and Al (5.9 x 10(-10) microg). Quantitative X-ray analysis of samples from nature showed PPB contain O (1.63 x 10(-8) microg), C (4.75 x 10(-9) microg), P (2.50 x 10(-9) microg), Mg (5.0 x 10(-10) microg), Ca (2.50 x 10(-10) microg), K (2.50 x 10(-10) microg), Fe (2.25 x 10(-10) microg) and S (2.0 x 10(-10) microg). The mass of an average polyphosphate body was 6.7 x 10(-8) microg for P. boryanum, 2.5 x 10(-8) microg for S. aureus and for microbes from the natural environment 6.3 x 10(-8) microg. The results indicate that the PPB may have other unknown functions in addition to essential element storage, acting as a detoxification method by sequestering heavy metals and providing a homeostasis system in the cell.     

Production of ultrafine gold and silver particles by means of a gas evaporation and solvent trap technique

Gold (Au) and Silver (Ag) colloids were produced in ethanol by a gas evaporation technique combined with a solvent trap method. Both the clusters in the solution and those collected before entering the solution were examined by transmission electron microscopy. The size of colloids in ethanol was 30 ∼ 100Åfor Au and 50 ∼ 200Åfor Ag. In contrast, the clusters collected before the solution trap had a dimension of 10 to 60Å, which is smaller than those trapped in ethanol. This size increase was brought about by coalescent growth in the solution, which took place when the solution temperature was raised from dry ice/acetone temperature to room temperature.     

The influence of polyunsaturated fatty acids on probiotic growth and adhesion

The establishment of the intestinal microflora, and probiotic bacteria, may control the inflammatory conditions in the gut. As polyunsaturated fatty acids (PUFA) possess antimicrobial activities, they may deter the action of probiotics. We assessed whether free linoleic, gamma-linolenic, arachidonic, alpha-linolenic and docosahexaenoic acids at physiological concentrations in the growth media would influence the growth and adhesion of Lactobacillus GG (probiotic), Lactobacillus casei Shirota (probiotic) and Lactobacillus bulgaricus (dairy strain). Higher concentrations of PUFA (10-40 microg PUFA ml(-1)) inhibited growth and mucus adhesion of all tested bacterial strains, whilst growth and mucus adhesion of L. casei Shirota was promoted by low concentrations of gamma-linolenic acid and arachidonic acid (at 5 microg ml(-1)), respectively. PUFA also altered bacterial adhesion sites on Caco-2 cells. Caco-2 cells grown in the presence of arachidonic acid were less adhered to by all three bacterial strains. Yet, L. casei Shirota adhered better on Caco-2 cells grown in the presence of alpha-linolenic acid. As the adhesion to mucosal surfaces is pivotal in health promoting effects by probiotics, our results indicate that the action of probiotics in the gut may be modulated by dietary PUFA.     

The effect of some pesticides on the rhythmic activity of adductor muscle of fresh-water mussel larvae

The effect of some pesticides on the rhythmic and tonic activity of adductor muscle of fresh-water mussel (Anodonta cygnea) larvae was investigated in short-term experiments. In the examined concentration range, Dimecron-50 does not influence the rhythmic activity of adductor muscles, while high concentrations of Gramoxone (is greater than 1 ml/l), Thimet-10 G (is greater than 5 x 10(-1) g/l) and Hungaria L-7 (is greater than 10(-1) g/l) cause a slight increase in it. These substances also induce a prolonged tonic contraction of a small proportion (10%) of larvae. Hungaria L-7 makes an exception, causing considerable contracture (30%). The concentrations inhibiting the TA activation by 50% are: 6x 10(-1) ml/l Dimecron-50; 2.5 x 10(-1) ml/l Gramoxone; 10(-1) g/l Hungaria L-7 and 8x 10(-2) g/l Thimet-10 G, while the 50% inhibition of the nonspecific ACh activation is resulted by 2 x 10(-1) ml/l D-50. It is concluded that contamination of environmental waters with Dimecron-50, Thimet-10 G or Hungaria L-7 may be injurious also for Pelecypoda larvae, that may contribute to the unbalancing of the water ecosystem.     

Occurrence of chromium resistant thermotolerant coliforms in tannery effluent

Twenty six thermotolerant strains resistant to high levels of chromium (50-250 microg/ml) were isolated from treated tannery effluent. They were also found resistant to multiple heavy metals and antibiotics. Majority of them were resistant to copper and bacitracin. Nine strains representing different resistance patterns were selected for plasmid profile and conjugation studies. Agarose gel electrophoresis results revealed that 6 strains harboured a single plasmid, whereas 3 strains exhibited 2 plasmid bands. Among antimicrobials, co-trimazole and bacitracin and among metals, Cu2+, Cd2+, Zn2+ and Ni2+ resistance were transferred most frequently at variable rates. However, chromium resistance was transferred in 6 strains with a frequency ranging 19-49x10(-2). Resistance to Co2+ and Hg2+ did not transfer under environmental conditions. Among the nine strains, three were found predominantly uropathogenic Escherichia coli (UPEC) serotype 04, whereas two strains were untypable. In addition, 4 transconjugants also showed a positive result after serotyping.     

Circular dichroism, kinetic and mass spectrometric studies of copper(I) and mercury(II) binding to metallothionein

The metalloprotein metallothionein (MT) is remarkable in its metal binding properties: for the mammalian protein, well-characterized species exist for metal to sulfur ratios of M7S20, M12S20, and M18S20, where M = Cd(II), Zn(II), Hg(II), Ag(I), Au(I), and Cu(I). Optical spectra in general, and circular dichroism (CD) and luminescence spectra in particular, provide rich detail of a complicated metal binding chemistry when metals are added directly to the metal-free or zinc-containing protein. CD spectral data unambiguously identify key metal to protein stoichiometric ratios that result in well-defined structures. Electrospray ionization-mass spectrometry data are reported for reactions in which Hg(II) binds to apo-MT 2A as previously described from CD data. Emission spectra in the 450-750 nm region have been reported for metallothioneins containing Ag(I), Au(I), and Cu(I). The luminescence of Cu-MT can also be detected directly from mammalian and yeast cells. We report both steady-state and new dynamic data for titrations of Zn-MT with Cu(I). Analysis of kinetic data for the addition of the first two Cu(I) atoms to Zn-MT indicates a first-order mechanism over a concentration range of 5-50 microM. Three-dimensional modeling was carried out using the results of the CD and EXAFS studies, model calculations for Zn7-MT, Hg7-MT, and Cu12-MT are described.     

Concentrations of cadmium,zinc, copper,iron, and metallothionein in liver and kidney of nonhuman primates

To evaluate the species specificity of Cd accumulation and the relationship of Cd with other essential metals and metallothionein (MT), the concentrations of Cd, Zn, Cu, and Fe in the liver and kidney and the MT concentrations in the soluble fractions of the liver and kidney were determined in Cd-uncontaminated nonhuman primates (11 species, 26 individuals) kept in a zoo and two wild-caught Japanese macaques. The compositions of metal-binding proteins in the soluble fractions were also investigated by high-performance liquid chromatography (HPLC). The hepatic Cd concentration was 0.03–14.0 μg/g and the renal Cd concentration was 0.35–99.0 μg/g, both varying greatly and being higher in nonhuman primates, which were more closely related to man. The hepatic Zn concentration was 24.0–176 μg/g and the renal Zn concentration was 13.5–138 μg/g, showing 7- to 10-fold differences, and a correlation (r=0.558, p<0.01) was found between renal Zn and renal Cd concentrations. It was proved that in the liver, MT is more closely correlated with Zn (r=0.795, p<0.001) than with Cd (r=0.492, p<0.01) and that in the kidney MT is correlated with both Cd (r=0.784, p<0.001) and Zn (r=0.742, p<0.001). HPLC analysis of metals bound to MT-like protein in chimpanzees, de Brazza’s monkeys, and Bolivian squirrel monkeys showed that more than 90% of Cd in both the liver and kidney, approx 40% of Zn in liver and 28–69% of Zn in kidney were bound to MT-like protein. The higher percentage Zn was bound to high-molecular protein.     

Increased synthesis of thromboxane A(2) and expression of procoagulant activity by monocytes in response to arachidonic acid in diabetes mellitus.

Thromboxane A(2) (TXA(2)) synthesis and expression of procoagulant activity (PCA) were investigated in mononuclear cells and monocytes prepared from a control and a Type 2 diabetic group. Monocytes from the diabetic group produced 2.10+/-0.81 ng of TXB(2)/5 x 10(5) monocytes compared to 1.26+/-0.43 ng/5 x 10(5) monocytes by the control group (P<0.01, n=11) when incubated in autologous plasma containing arachidonic acid (200 microg/ml). When monocytes were incubated in buffer containing arachidonic acid (20 microg/ml), cells from the diabetic group produced 1.65+/-0.68 ng of TXB(2)/5 x 10(5) monocytes compared to 1.07+/-0.31 ng/5 x 10(5) monocytes by the control group (P<0.02, n=12). Expression of PCA was examined in mononuclear cell preparations. Basal and maximally stimulated PCA with lipopolysaccharide (4.2 microg/ml) were not different between control and diabetic groups. However, arachidonic acid induced a four-fold (P<0.001) increase in PCA in the diabetic group. This activity was characterized as tissue factor. Increased synthesis of TXA(2) and expression of PCA may potentiate thrombosis and increase fibrin deposition, events that play primary roles in the development of vascular disease.     

Kakadumycins,novel antibiotics from Streptomyces sp NRRL 30566, an endophyte of Grevillea pteridifolia

An endophytic streptomycete (NRRL 30566) is described and partially characterized from a fern-leaved grevillea (Grevillea pteridifolia) tree growing in the Northern Territory of Australia. This endophytic streptomycete produces, in culture, novel antibiotics - the kakadumycins. Methods are outlined for the production and chemical characterization of kakadumycin A and related compounds. This antibiotic is structurally related to a quinoxaline antibiotic, echinomycin. Each contains, by virtue of their amino acid compositions, alanine, serine and an unknown amino acid. Other biological, spectral and chromatographic differences between these two compounds occur and are given. Kakadumycin A has wide spectrum antibiotic activity, especially against Gram-positive bacteria, and it generally displays better bioactivity than echinomycin. For instance, against Bacillus anthracis strains, kakadumycin A has minimum inhibitory concentrations of 0.2-0.3 microg x ml(-1) in contrast to echinomycin at 1.0-1.2 microg x ml(-1). Both echinomycin and kakadumycin A have impressive activity against the malarial parasite Plasmodium falciparum with LD(50)s in the range of 7-10 ng x ml(-1). In macromolecular synthesis assays both kakadumycin A and echinomycin have similar effects on the inhibition of RNA synthesis. It appears that the endophytic Streptomyces sp. offer some promise for the discovery of novel antibiotics with pharmacological potential.