Incidence of ESBL producers amongst Gram-negative bacilli isolated from intra-abdominal infections across India (based on SMART study, 2007 data).

OBJECTIVES: This study was conducted in 9 centers spread over India from January 1 to December 31, 2007 to monitor in vitro susceptibility of Gram-negative bacilli to Group I carbapenem, ertapenem and other antimicrobials in intra-abdominal infections and to identify early changes in susceptibility pattern of community or hospital acquired organisms, with a focus on ESBL producers. MATERIAL AND METHODS: Gram-negative bacilli isolated from intra-abdominal samples of patients with documented intra-abdominal infections were processed for identification by conventional/ automated methods and antimicrobial susceptibility by Micro-Scan (Siemens) MIC panel against 12 antimicrobials (3rd and 4th generation cephalosporins, Groups I and II carbapenems, amikacin, levofloxacin, amoxicillin-clavulanic acid and piperacillin-tazobactam). RESULTS: A total of 588 isolates were identified, of which 351 (60%) were E. coli and 114 (19%) were Klebsiella spp. 79% of E. coli and 70% of Klebsiella spp. were ESBL producers in general. 110 of E. coli and 35 of Klebsiella isolates were from community-acquired intra-abdominal infections. 80% of E. coli and 63% of Klebsiella isolates from community-acquired infections were ESBL producers, against 79% of E. coli and 73% of Klebsiella isolates from hospital-acquired infections. Amongst the ESBL-positive isolates of E. coli, 94% were susceptible in vitro to ertapenem, 96% to imipenem and 76% to piperacillin-tazobactam. For ESBL-positive isolates of Klebsiella spp., the corresponding figures were 80%, 94% and 59% respectively. CONCLUSION: The study showed a high incidence of ESBL-producers amongst Enterobacteriaceae isolates from intra-abdominal infections in both community-acquired and hospital-acquired settings across India. Ertapenem was comparable with imipenem against ESBL-positive E. coli isolates, while imipenem was more effective than ertapenem against ESBL-positive Klebsiella isolates.

Potentiality of a new compound for in vitro differentiation between halophilic and non-halophilic vibrios.

Sensitivity of 21 halophilic vibrios and 16 clinical isolates of non-halophilic vibrios was determined against a new possible antivibrio agent, a pyrimidine analogue, 4, 6-dimethylpyrimidine -2-thiol (4,6-DMPT). It appeared to be a vibriocidal agent, having a mean MIC and MBC of 32 microg/ml for halophilic strains and 64 microg/ml for non-halophilic strains and an LD50 of 300 mg/Kg body weight of mice. Thus, 4,6-DMPT may help an in vitro distinction between halophilic and non-halophilic vibrios. Sensitivity of these strains was also studied with respect to pteridine, crystal violet and Tween 80 hydrolysis as further markers distinguishing between these 2 groups which could also be differentiated by their growth on TCBS or/and CLED media.

Crystal structure of imidazole glycerol phosphate synthase: a tunnel through a (beta/alpha)8 barrel joins two active sites.

BACKGROUND: Imidazole glycerol phosphate synthase catalyzes a two-step reaction of histidine biosynthesis at the bifurcation point with the purine de novo pathway. The enzyme is a new example of intermediate channeling by glutamine amidotransferases in which ammonia generated by hydrolysis of glutamine is channeled to a second active site where it acts as a nucleophile. In this case, ammonia reacts in a cyclase domain to produce imidazole glycerol phosphate and an intermediate of purine biosynthesis. The enzyme is also a potential target for drug and herbicide development since the histidine pathway does not occur in mammals. RESULTS: The 2.1 A crystal structure of imidazole glycerol phosphate synthase from yeast reveals extensive interaction of the glutaminase and cyclase catalytic domains. At the domain interface, the glutaminase active site points into the bottom of the (beta/alpha)(8) barrel of the cyclase domain. An ammonia tunnel through the (beta/alpha)(8) barrel connects the glutaminase docking site at the bottom to the cyclase active site at the top. A conserved "gate" of four charged residues controls access to the tunnel. CONCLUSIONS: This is the first structure in which all the components of the ubiquitous (beta/alpha)(8) barrel fold, top, bottom, and interior, take part in enzymatic function. Intimate contacts between the barrel domain and the glutaminase active site appear to be poised for crosstalk between catalytic centers in response to substrate binding at the cyclase active site. The structure provides a number of potential sites for inhibitor development in the active sites and in a conserved interdomain cavity.

Structures of cellular retinoic acid binding proteins I and II in complex with synthetic retinoids.

Retinoids play important roles in diverse cellular processes including growth, cell differentiation and vision. Many natural and synthetic retinoids are used as drugs in dermatology and oncology. A large amount of data has been accumulated on the cellular activity of different synthetic retinoids. They are stabilized and transported inside the cell cytoplasm by binding and transport proteins, such as cellular retinol-binding proteins and cellular retinoic acid binding proteins (CRABPs). The structures of human CRABP II in complex with two different synthetic retinoids, Ro13-6307 and Ro12--7310 (at 2.1 and 2.0 A resolution, respectively) and of bovine CRABP I in complex with a retinobenzoic acid, Am80 (at 2.8 A resolution) are described. The binding affinities of human CRABP I and II for the retinoids studied here have been determined. All these compounds have comparable binding affinities (nanomolar range) for both CRABPs. Apart from the particular interactions of the carboxylate group of the retinoids with specific protein groups, each structure reveals characteristic interactions. Studying the atomic details of the interaction of retinoids with retinoid-binding proteins facilitates the understanding of the kinetics of retinoid trafficking inside the cytoplasm.

The structures of alpha 2u-globulin and its complex with a hyaline droplet inducer.

Alpha 2u-globulin (A2U) is the major urinary protein excreted by adult male rats. The structure of a monoclinic crystal form of A2U was reported in 1992 [Böcskei et al. (1992). Nature (London), 360, 186-188]. The structures of an orthorhombic crystal form of A2U at 2. 5 A resolution (refined to an R factor of 0.248; Rfree = 0.264) and of a complex between A2U and d-limonene 1,2-epoxide (DLO) at 2.9 A resolution (R factor = 0.248; Rfree = 0.260) are presented here. DLO is one of a diverse group of chemicals which cause a male rat-specific renal carcinogenesis called hyaline-droplet nephropathy. The rate-determining step in the development of this disorder is the binding of the toxin to A2U. Comparison of the cavities in A2U and in the corresponding mouse urinary protein (MUP) reveal that the former is tailor-made for small oval hydrophobic ligands such as DLO. The cavity in MUP is more shallow and elongated and cannot easily accommodate such ligands.

Structure of D-allose binding protein from Escherichia coli bound to D-allose at 1.8 A resolution.

ABC transport systems for import or export of nutrients and other substances across the cell membrane are widely distributed in nature. In most bacterial systems, a periplasmic component is the primary determinant of specificity of the transport complex as a whole. We report here the crystal structure of the periplasmic binding protein for the allose system (ALBP) from Escherichia coli, solved at 1.8 A resolution using the molecular replacement method. As in the other members of the family (especially the ribose binding protein, RBP, with which it shares 35 % sequence homology), this structure consists of two similar domains joined by a three-stranded hinge region. The protein is believed to exist in a dynamic equilibrium of closed and open conformations in solution which is an important part of its function. In the closed ligand-bound form observed here, D-allose is buried at the domain interface. Only the beta-anomer of allopyranose is seen in the crystal structure, although the alpha-anomer can potentially bind with a similar affinity. Details of the ligand-binding cleft reveal the features that determine substrate specificity. Extensive hydrogen bonding as well as hydrophobic interactions are found to be important. Altogether ten residues from both the domains form 14 hydrogen bonds with the sugar. In addition, three aromatic rings, one from each domain with faces parallel to the plane of the sugar ring and a third perpendicular, make up a hydrophobic stacking surface for the ring hydrogen atoms. Our results indicate that the aromatic rings forming the sugar binding cleft can sterically block the binding of any hexose epimer except D-allose, 6-deoxy-allose or 3-deoxy-glucose; the latter two are expected to bind with reduced affinity, due to the loss of some hydrogen bonds. The pyranose form of the pentose, D-ribose, can also fit into the ALBP binding cleft, although with lower binding affinity. Thus, ALBP can function as a low affinity transporter for D-ribose. The significance of these results is discussed in the context of the function of allose and ribose transport systems.

Antibiotic sensitivity patterns of actinomycetes isolated from patients of actinomycetoma.

The effectiveness of eight antibiotics against 30 human isolates of actinomycetoma agents belonging to 7 different species were tested by agar dilution and disc diffusion methods to evaluate the susceptibility patterns and to study drug resistance among the organisms. It was found that many of the isolates had developed partial or complete resistance to conventionally used antibiotics like cotrimoxazole, streptomycin and ampicillin, but almost all were sensitive to amikacin and ciprofloxacin. The two methods were equally effective for detecting sensitivity patterns of the Nocardia isolates.

Effect of yogic exercises on thyroid function in subjects resident at sea level upon exposure to high altitude.

Using radioactive iodine, the effect of 1 month's yogic exercises has been investigated on the thyroid function of subjects resident at sea level (SL) specially after their exposure to high altitude (HA). The results have been compared with a group of SL subjects who underwent physical training (PT) exercises for the same duration. Ten healthy male volunteers in the age range of 20-30 years were used as test subjects in this study with each serving as his own control. The subjects were randomly divided into two groups of 5 each. One group practised hatha yogic exercises, while the other group performed the regular PT exercises. The thyroidal accumulation and release of radioactive iodine have been measured in each of the subjects of both groups before and after 1 month of their respective exercises at SL. One month of yogic exercises at SL has been observed to cause a significant reduction in the trans-thyroidal availability of radioiodine. The thyroid radioactivity in this group of subjects was always below normal levels with the exception of two peaks of radioactive iodine uptake, when the levels of radioactivity in the thyroid were similar to the control values of pre-yogic exercises. The release of radiolabel at 24-48 h was significantly increased after yogic exercises. In contrast, the subjects performing PT exercises for the same duration at SL showed significant thyroid uptake of radioactive iodine at 24 h. Subsequently their 131I uptake continued to rise slowly until 72 h without any demonstrable thyroidal release of radiolabel. This indicated that increased thyroid activity was induced by conventional PT exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered maternal thyroid function: fetal and neonatal heart cholesterol and phospholipids.

The influence of maternal thyroid function on the fetal and neonatal myocardial cholesterol and phospholipid content was studied in rats. Fetuses born to hyperthyroid mothers had decreased total cholesterol and increased esterified cholesterol while offsprings born to hypothyroid mothers had increased total, free and esterified cholesterol during late gestation and/or at term. Phospholipid fractions phosphatidyl choline and phosphatidyl ethanolamine in offsprings born to hyperthyroid mothers were not significantly changed. Offsprings born to hypothyroid mothers had decreased total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine at fetal and neonatal stages. 3H-acetate incorporation in phosphatidyl choline and phosphatidyl ethanolamine was also decreased. Maternal thyroid seems to have important role in the regulation of cholesterol and phospholipid metabolism in fetal and neonatal hearts.

Thyroidal handling of radioiodine in sea level residents exposed to hypobaric hypoxia.

In the present investigation thyroidal accumulation of radioiodine and its release were assessed by direct testing of thyroid function using radioactive iodine, in vivo, in sea level residents intermittently exposed to hypobaric hypoxia. Thyroidal accumulation of radioiodine and its turnover were examined daily for 14 days. Twelve healthy human male volunteers were divided into three groups, with an equal number of individuals in each group. A decompression chamber was used to expose each group of subjects to hypoxic conditions at a simulated altitude of 3810 m for 8 h/day for 14 days. An oral dose of 25 mu Ci iodine-131 was administered to each individual of the first group immediately before the initiation of intermittent hypoxia. The second group of subjects received a tracer dose at the beginning of the 4th day of the 14 days, intermittent exposure to hypoxia, while the third group received the tracer dose 1 week after the completion of the exposure. Control studies were carried out on the subjects before they were subjected to the experimental conditions. Thyroidal accumulation of 131I in experimental subjects during the hypoxic state and in the post-hypoxic state was higher than in the control studies. The pattern of accumulation during exposure to hypoxia and in the post-hypoxic state showed multiple peaks of radioactive iodine uptake (PRAIU), a unique feature. The multiple PRAIU by the thyroid in experimental subjects were sharp and of short duration, reflecting an increased rate of 13I release from the thyroid. Control subjects had a single PRAIU by the thyroid 24 h after the administration of tracer.

Altered maternal thyroid function: fetal and neonatal myocardial metabolism.

The influence of the maternal thyroid status on the fetal and neonatal myocardial protein, carbohydrate and lipid metabolism was studied in rats. The neonates born of hypothyroid mothers could not survive beyond 8 days after birth. The offsprings born of hypothyroid mothers showed growth retardation, decreased level of heart mitochondrial protein, reduced myocardial free fatty acid (FFA) oxidation at birth and afterwards, low glucose oxidation by the heart at later fetal stages, and afterwards, despite low heart glycogen reserve, glucose oxidation was high. The offsprings born of hyperthyroid mothers showed stimulation in overall growth, increased myocardial FFA oxidation and increased 14C-glucose incorporation into glycogen as well as increased myocardial glucose oxidation during fetal stages. Results indicate that maternal thyroid hormones play an important role in the metabolic control of fetuses and neonates.

Altered maternal thyroid function: fetal and neonatal development of rat.

Influence of maternal thyroid status on fetal and neonatal development of rats has been studied. Maternal hypothyroidism resulted impaired reproduction and intrauterine growth retardation of offsprings as revealed by their reduced body weight, heart weight, body length and tail length. Offsprings born to hypothyroid mothers showed very high rate of mortality and none of them survived beyond eight days. Maternal hyperthyroidism did not cause any abnormality on reproduction. Hyperthyroid mothers showed increased rate in body weight gain during pregnancy which was associated with increased weight of body and heart of fetuses born to hyperthyroid mothers. Plasma thyroxine was not measurable in fetus from hypothyroid mothers till 21st day of gestation. The results of the present study showed that maternal thyroid status plays an important role in fetal and neonatal growth and development.

Effect of ionizing radiation on tissue cyclic AMP and GMP in experimental rats.

Adult male Sprague Dawley rats were exposed to whole-body gamma radiation of 4 Gy and 10 Gy and cyclic AMP and GMP of several tissues were studied 4 hours, 24 hours and 72 hours after irradiation. Animals exposed to 4 Gy exhibited initial increase and subsequent decrease of plasma cyclic AMP, while opposite effects were noted in plasma cyclic GMP. Both groups of irradiated rats showed significant decrease of spleen cyclic AMP with variable responses in cyclic GMP. Initial increase with subsequent decrease of liver cyclic AMP was observed in irradiated animals with unaltered cyclic GMP values. It was interesting to note variable responses of myocardial cyclic AMP in both groups of experimental rats with a significant increase in heart cyclic GMP in rats exposed to 10 Gy only. In contrast, myocardial cyclic GMP was significantly decreased in rats exposed to 4 Gy groups.

Effect of alloxan diabetes and phenformin on insulin binding with liver plasma membrane receptors.

Effect of phenformin on [125I]insulin binding with the liver plasma membrane of normal and alloxan diabetic rats was studied in vitro. Diabetic rats showed a decreased binding of [125I]insulin with liver plasma membrane indicating thereby a decreased binding affinity of insulin with its receptors. Phenformin caused an increased binding of [125I]insulin with liver plasma membrane in normal as well as in diabetic rats. Results of this study indicate that the control of diabetes by phenformin is possibly affected by increasing the binding of insulin with plasma membrane receptors which in turn promotes insulin dependent metabolic reactions at the cellular level.

Hypolipidemic effect of garlic and thyroid function.

Male Sprague-Dawley rats were maintained on cholesterol and garlic oil for 12 weeks. Cholesterol induced hyperlipidemia was controlled by garlic feeding. Garlic treatment did not alter the concentrations of circulating thyroid hormones and thyroidal uptake of radioiodine. The results indicate that the hypolipidemic effect of garlic is probably not mediated through the thyroid.

Effect of sexual cycle on red cell membrane permeability as revealed by influx of Rubidium-86 and adenosinetriphosphatase in female rats.

Red cell membrane permeability, as revealed by influx of Rubidium-86 and ATPase activity, was studied in different phases of sexual cycle in female rats and no significant changes have been found.

Effect of whole body gamma radiation on reduced glutathione contents of rat tissues.

Reduced glutathione (GSH) contents of blood, heart, liver and spleen were studied after one, four and seven days of irradiation in rats. Blood GSH in rats exposed to 4 Gy remained unaltered throughout, while animals exposed to 8 Gy showed significant decrease of blood GSH on the 8th day after exposure. Diminution of liver and heart GSH contents was observed initially in both groups of irradiated rats, while the reverse was noted in spleen GSH contents of experimental animals.

Effect of whole-body gamma radiation on some metals of rat plasma.

Adult male rats were exposed to 4 and 10 Gy of whole-body gamma radiation, and several metals of plasma were studied on 1st, 3rd and 6th day after exposure. Lethal radiation increased plasma calcium initially with subsequent diminution, while plasma magnesium decreased initially in both groups, becoming normal on the 6th day post exposure. Plasma iron in 4-Gy exposed rats diminished on 3rd day, while the same in 10-Gy exposed animals increased initially and then decreased. Both groups of animals exhibited significant diminution of plasma copper and ceruloplasmin from the 3rd day post irradiation. Plasma monoamine oxidase (MAO) was enhanced from 1st day post exposure in 10-Gy exposed rats, which persisted still 6th day. Liver monoamine oxidase was significantly diminished from 1st day after exposure in lethally exposed rats, while spleen monoamine oxidase, after initial increase was normalised on 6th day post irradiation.