Ascorbic acid formulation for survivability and diazotrophic efficacy of Azotobacter chroococcum Avi2 (MCC 3432) under hydrogen peroxide stress and its role in plant-growth promotion in rice (Oryza sativa L.).

Oxidative stress generates reactive oxygen species which causes cell damage of living organisms and are normally detoxified by antioxidants. Indirect reports signify the damages caused by reactive oxygen species and neutralized by antioxidant, but the direct evidence to confirm this hypothesis is still unclear. To validate our hypothesis, an attempt was made in a diazotrophic bacterium (Azotobacter chroococcum Avi2) as a biological system, and hydrogen peroxide (H2O2) and ascorbic acid were used as oxidative stress and antioxidant supplement, respectively. Additionally, rice plant-growth attributes by Avi2 was also assessed under H2O2 and ascorbic acid. Results indicated that higher concentration of H2O2 (2.5 mM-4.5 mM) showed the complete mortality of Avi2, whereas one ppm ascorbic acid neutralized the effect of H2O2. Turbidity, colony forming unit, DNA quantity, nifH gene abundance, indole acetic acid and ammonia productions were significantly (p < 0.5) increased by 11.93%, 17.29%, 19.80%, 74.77%, 71.89%, and 42.53%, respectively in Avi2-treated with 1.5 mM H2O2 plus ascorbic acid compared to 1.5 mM H2O2 alone. Superoxide dismutase was significantly (p < 0.5) increased by 60.85%, whereas catalase and ascorbate peroxidase activities were significantly (p < 0.05) decreased by 64.28% and 68.88% in Avi2-treated with 1.5 mM H2O2 plus ascorbic acid compared to 1.5 mM H2O2 alone. Germination percentage of three rice cultivars (FR13a, Naveen and Sahbhagi dhan) were significantly (p < 0.5) increased by 20%, 13.33%, and 4%, respectively in Avi2-treated with 0.6 mM H2O2 plus ascorbic acid compared with uninoculated control. Overall, this study indicated that ascorbic acid formulation neutralizes the H2O2-oxidative stress and enhances the survivability and plant growth-promoting efficacy of A. chroococcum Avi2 and therefore, it may be used as an effective formulation of bio-inoculants in rice under oxidative stress.

Mosquito control by larvivorous fish.

There is growing of the effects of insecticide used controlling the vectors of human diseases. Manipulating or introducing an auto-reproducing predator into the ecosystem may provide sustained biological control of pest populations. The selection of a biological agent should be based on its self-replicating capacity, preference for the target pest population in the presence of alternate natural prey, adaptability to the introduced environment, and overall interaction with indigenous organisms. In order to achieve an acceptable range of control, a sound knowledge of various attributes of interactions between the pest population and the predator to be introduced is desirable. Biological larviciding for the control of mosquito borne diseases is feasible and effective only when breeding sites are relatively few or are easily identified and treated. Larval control appears to be promising in urban areas, given that the density of humans needing protection is higher than the limited number of breeding sites. Since 1937, fish have been employed for controlling mosquito larvae. Different types of fish have been used so far in this operational technique. However, use of fish of indigenous origin is found to be more appropriate in this operation. This review presents information on different larvivorous fish species and the present status of their use in mosquito control and provides a ready reference for workers involved and interested in mosquito research.

Lipopolysaccharides of Vibrio cholerae: III. Biological functions.

This review presents the salient features of the biological functions including the (i) endotoxic activities, (ii) antigenic properties, (iii) immunological responses to and (iv) phage receptor activities of the Vibrio cholerae lipopolysaccharides (LPS). The biological functions of the capsular polysaccharide (CPS) of V. cholerae have also been discussed briefly as a relevant topic. The roles of LPS and other extracellular polysaccharides in the (i) intestinal adherence and virulence of the vibrios and (ii) the biofilm formation by the organisms have been analysed on the basis of the available data. Every effort has been made to bring out, wherever applicable, the lacunae in our knowledge. The need for the continuous serogroup surveillance and monitoring of the environmental waters and the role of LPS in the designing of newer cholera vaccines has been discussed briefly in conclusion.

Eco-friendly control of mosquito larvae by Brachytron pratense nymph.

The study reported here revealed the biocontrol efficacy of aquatic nymphs of the dragonfly Brachytron pratense against larvae of the mosquito Anopheles subpictus. It was found that during a 24-hour study period, a nymph of B. pratense would consume (mean value of three observations) 66 fourth-instar An. subpictus larvae released in a water bowl containing 3 liters of pond water. The consumption rate was significantly higher (p < .05) during the lights-on phase of the experiment than during the lights-off phase (t = 2.15). Under field conditions, a significant decrease (p < .05) in larval density in dipper samples was observed 15 days after the introduction of dragonfly nymphs (10 individuals) in concrete tanks. The biocontrol potential of the nymphs under field conditions was also indicated by a significant increase (p < .05) in the density of mosquito larvae 15 days after the removal of nymphs. In the control tanks (where no nymphs were introduced), mean larval-mosquito density did not differ significantly throughout the study period (p > .05).

Lymphatic filariasis in the coastal areas of Digha, West Bengal, India.

The state of West Bengal, India, has a long coastline with the Bay of Bengal. No information exists regarding filarial epidemiology and its vector in these coastal areas. The present study was designed to assess the epidemiology of lymphatic filariasis and the role of available mosquitoes as its vector in eight coastal villages around Digha, West Bengal. Night blood samples of 4016 individuals were collected and each of them was examined clinically for any manifestations of the disease. Overall, microfilaria rate, mean microfilarial density and disease rate were 9.06%, 8.63% and 7.72%, respectively. The causative parasite was identified as Wuchereria bancrofti and Culex quinquefasciatus was incriminated as the vector responsible. Vector infection and infectivity rates were assessed to be 12.5% and 0.73%, respectively. The human blood index of human-house-frequenting vector population was 70%. Vector density, vector infection, infectivity rates and human blood index were higher in the rainy season in the study area. Overall, the filarial situation was bad and, as a measure, single-dose diethylcarbamazine citrate (6 mg/kg body weight) treatment was given to all the microfilariaemic patients. Night blood samples of the treated individuals were tested for microfilariae on days 10 and 365, which revealed interesting results.

Lipopolysaccharides of Vibrio cholerae II. Genetics of biosynthesis.

An account of our up to date knowledge of the genetics of biosynthesis of Vibrio cholerae lipopolysaccharide (LPS) is presented in this review. While not much information is available in the literature on the genetics of biosynthesis of lipid A of V. cholerae, the available information on the characteristics and proposed functions of the corepolysaccharide (core-PS) biosynthetic genes is discussed. The genetic organizations encoding the O-antigen polysaccharides (O-PS) of V. cholerae of serogroups O1 and O139, the disease causing ones, have been described along with the putative functions of the different constituent genes. The O-PS biosynthetic genes of some non-O1, non-O139 serogroups, particularly the serogroups O37 and O22, and their putative functions have also been discussed briefly. In view of the importance of the serogroup O139, the origination of the O139 strain and the possible donor of the corresponding O-PS gene cluster have been analyzed with a view to having knowledge of (i) the mode of evolution of different serogroups and (ii) the possible emergence of pathogenic strain(s) belonging to non-O1, non-O139 serogroups. The unsolved problems in this area of research and their probable impact on the production of an effective cholera vaccine have been outlined in conclusion.

Lipopolysaccharides of Vibrio cholerae. I. Physical and chemical characterization.

Vibrio cholerae is the causative organism of the disease cholera. The lipopolysaccharide (LPS) of V. cholerae plays an important role in eliciting the antibacterial immune response of the host and in classifying the vibrios into some 200 or more serogroups. This review presents an account of our up-to-date knowledge of the physical and chemical characteristics of the three constituents, lipid-A, core-polysaccharide (core-PS) and O-antigen polysaccharide (O-PS), of the LPS of V. cholerae of different serogroups including the disease-causing ones, O1 and O139. The structure and occurrence of the capsular polysaccharide (CPS) on V. cholerae O139 have been discussed as a relevant topic. Similarity and dissimilarity between the structures of LPS of different serogroups, and particularly between O22 and O139, have been analysed with a view to learning their role in the causation of the epidemic form of the disease by avoiding the host defence mechanism and in the evolution of the newer pathogenic strains in future. An idea of the emerging trends of research involving the use of immunogens prepared from synthetic oligosaccharides that mimic terminal epitopes of the O-PS of V. cholerae O1 in the development of a conjugate anti cholera vaccine is also discussed.

Interaction of furazolidone with DNA.

DN forms a complex with furazolidone producing thereby a quenching and a bathochromic shift of the drug absorption pattern. The binding isotherm was a non-linear one indicating involvement of more than one binding process in the formation of the furazolidone - DNA complex. The furazolidone - DNA complex inhibited digestion of DNA by DNAase and stabilized DNA against thermal strand separation by a significant degree.

Liposomes as membrane model for study of lipid peroxidation.

This article describes the properties, production and characterization of liposomes with special reference to their use as membrane model for the study of lipid peroxidation. It presents briefly the methods that can be used for the assay of liposomal lipid peroxidation and brings out the special advantages these liposomes provide in elucidating the mechanism of lipid peroxidation by different physical and chemical agents. Studies involving liposomal lipid peroxidation by different agents and the consequent changes in the structure and function of liposomal membrane have been reviewed briefly.

Prospective study of the prevalence and symptomatology of cytomegalovirus infection in renal transplant recipients.

To determine the incidence and symptomatology of cytomegalovirus (CMV) infection in renal transplant recipients, we followed 40 patients prospectively for 5 to 24 months after operation. As judged by the serological change and virus isolation from blood and/or urine, the infection rate for the entire group was 82% (33 of 40 patients). Two types of infection were recognized: primary infection that occurred in 3 patients, and reactivation infection that occurred in 30 patients. Twenty-one patients were asymptomatic and 12 were mildly symptomatic. Four had mild hepatic dysfunction; two had the CMV mononucleosis syndrome associated with mild to moderate deterioration of renal function. Two patients had hyperglycemia. One patient who reached a CMV antibody titer of 1:32,768 was totally asymptomatic other than fever of short duration. CMV-induced pneumonitis or retinitis was not noted, and there was no mortality from CMV infection in our patients. Factors which may be associated with the absence of severe manifestations of active CMV infection in these patients are discussed.

Failure of B-cold lymphocytotoxins to enhance cadaveric renal allograft survival.

In a three-year period between January 1980 and December 1982, 242 consecutive cadaver transplant recipients in one center were tested before transplantation by cytotoxicity against a random panel of T and B lymphocytes at 5 degrees C and 37 degrees C incubation. They were also tested for HLA-A, B, and DR antigens. Kidney transplants were carried out with the primary objective of achieving a two-DR match. Kidney transplants were carried out only in the absence of T-warm positive cross-matches. All patients were followed for a minimum period of one year after transplant. There have been no exclusions, and all causes of failure, including death, have been counted as graft losses. Patients were stratified according to HLA-A, B, and DR matches and were also divided into high-antibody and low-antibody groups. The recipients with no antibodies had the best one-year graft survival (66%). Recipients with B-cold antibodies did not have enhanced one-year graft survival (51%). Recipients with B-warm antibodies did indifferently (56%). The worst results were seen in recipients who had pretransplant T-warm antibodies (42%) though the number of patients in this group was small.

Effect of UV-A on the linolenic acid micelles.

UV-A produced a dose-dependent linear increase of peroxidation in linolenic acid micelles as detected by the assay of (i) conjugated dienes, (ii) hydroperoxides, (iii) malondialdehyde (MDA), and (iv) the fluorescent adduct formed by the reaction of MDA with the amino acid, glycine. While sodium formate, dimethyl sulfoxide, superoxide dismutase, and ethylenediamine-tetraacetic acid produced no significant inhibition, some generally used singlet oxygen quenchers, beta-carotene, dimethylfuran, L-histidine, and sodium azide, caused significant inhibition of the UV-A-induced peroxidation of the linolenic acid micelles. alpha-Tocopherol and butylated hydroxytoluene produced more than 90% inhibition of the UV-A-induced peroxidation. ESR spectrometry revealed the formation of 2,2,6,6-tetramethylpiperidine oxide in the UV-A-irradiated aqueous solution of 2,2,6,6-tetramethylpiperidine. The involvement of singlet oxygen (1O2) in the UV-A-induced peroxidation of linolenic acid micelles is discussed.

Peroxidation of the dried thin film of lipid by high-energy alpha particles from a cyclotron.

High-energy alpha particles produced a dose-dependent linear increase in different lipid peroxidation products (e.g., malondialdehyde (MDA), conjugated dienes, and hydroperoxides) in the dried thin film state. An inverse dose-rate effect was observed when the dose rate was varied by changing either the alpha-particle fluence rate or the alpha-particle energy. The antioxidants alpha-tocopherol and butylated hydroxytoluene (BHT) suppressed the alpha-particle-induced lipid peroxidation in the dried thin film state, and in this respect alpha-tocopherol was found superior to BHT. It was found that alpha-tocopherol was equally efficient in inhibiting lipid peroxidations by alpha particles and ultraviolet light.

The induction of lipid peroxidation in liposomal membrane by ultrasound and the role of hydroxyl radicals.

Ultrasonic radiation produced a dose-dependent linear increase in lipid peroxidation in the liposomal membrane as reflected in the measurements of conjugated dienes, lipid hydroperoxides, and malondialdehydes (MDA). Production of MDA was confirmed by spectrophotometric and spectrofluorometric methods including the detection of excitation (360 nm) and emission (435 nm) maxima characteristic of the MDA-glycine adduct formed after addition of glycine in the system. Ultrasound of frequencies 20 kHz (used for laboratory purposes) and 3.5 MHz (used for clinical purposes) produced MDA in an identical manner. Ultrasound-induced lipid peroxidation was enhanced synergistically by 2.5 X 10(2) microM ascorbic acid but inhibited significantly by 10(4) microM ascorbic acid. Ultrasound-induced production of MDA could not be inhibited to any significant degree by superoxide dismutase, histidine, dimethylfuran, or beta-carotene but was very significantly inhibited by cholesterol (93%), butylated hydroxytoluene (88%), alpha-tocopherol (85%), sodium benzoate (80%), dimethyl sulfoxide (80%), sodium formate (64%), and EDTA (64%). The scavenger studies indicated the functional role of OH radicals in the initiation of ultrasound-induced lipid peroxidation.

Abnormal serum lipid patterns in primary renal allograft recipients.

The blood lipids profile was determined in 59 patients with successful primary renal allografts, who were followed for an average period of 31.8 months (range, 6 to 80 months). Elevated levels of cholesterol (greater than 250 mg/100 ml) were found in 51% of the patients, elevated levels of triglycerides were found in 56%, and elevated levels of phospholipids in all but one of the patients who were studied (45 of 46). Correlation analysis revealed significant relationships among the systolic blood pressure with total cholesterol (r equals 0.36, P less than 0.01), triglycerides (r equals 0.56, p is less than 0.001), and phospholipids (r equals 0.40, P is less than 0.001). No significant correlations were found between the lipid levels and daily prednisone dosage or with the duration of the period following transplantation. The most significant finding in our study was an elevation of serum phospholipid level--a pattern unreported previously in transplant recipients but which has been reported to be associated with hepatic derangement in nontransplant population. Of 32 patients who had elevated levels of serum phospholipids, the liver function tests were abnormal in 22 patients (69%).

Ascorbic acid metabolism in diabetes mellitus.

In contrast to normal subjects diabetic patients and very low plasma ascorbic acid and significantly high (p less than 0.001) dehydroascorbic acid irrespective of age, sex, duration of the disease, type of treatment, and glycemic control. However, there was no significant difference between the mean leukocyte ascorbate concentrations of the two populations. The in vitro rates of dehydroascorbate reduction in the hemolysate and the erythrocyte reduced glutathione levels and the glucose-6-phosphate dehydrogenase activities, which regulate the dehydroascorbate reduction, were similar in normal and diabetic subjects. The turnover of ascorbic acid was higher in the diabetics than that in the normal volunteers. Experiments with diabetic rats indicated that the increased turnover of ascorbic acid was probably due to increased oxidation of ascorbate to dehydroascorbate in tissue mitochondria. Ascorbic acid supplementation at a dose of 500 mg per day for a brief period of 15 days resulted in an increase in the plasma ascorbate level temporarily, but it did not lower the blood glucose level of the diabetic patients.

Antithymocyte globulin in renal transplant recipients. Report of a prospective randomized controlled trial.

Horse antihuman thymocyte globulin (HAHTG) combined with prednisone and azathioprine (lmuran) was used as immunosuppressive therapy in a randomized controlled sutdy in 50 renal allograft recipients. Side effects of HAHTG administration given intravenously were mostly mild. In the treated group, four patients out of 26 died of infectious complications, whereas in the control group, three patients out of 24 died of infectious complications (chi2 = .01,P greater than .05). The graft survival at 18 months was ten of 24 in the control group and ten of 26 in the treated group (chi2 = 1.26, P greater than .05). Cumulative graft survival was 58.3% in the control group and 38.1% in the treated group at 18 months. However, if we consider the people who died with a functioning graft not as graft failure but as if they left the study, then the cumulative graft survival is 64.5% in the control group and 65.9% in the treated group. Thus, the mortality from infective causes and graft survival were not significantly different between the two groups. Hence, we draw the conclusion that use of HAHTG did not exert a beneficial effect on the ultimate outcome.

Early severe renal allograft rejection.

An early, severe form of renal allograft rejection, occuring after an initial day or more of good function and within the first week after transplantation, is an increasingly recognized phenomenon. This type of rejection occurred in 17 of 187 (9%) postmortem-donor renal transplants. It could only be reversed in four grafts, and two of these failed because of recurrent rejection within four months. No clinical observations were helpful in determining which cases were likely to respond to antirejection therapy. Of the 17 patients, four died. Because of the poor graft survival and the high mortality, attempts to treat early severe rejection may not be warranted.

Pulmonary infections. The Minnesota randomized prospective trial of cyclosporine vs azathioprine-antilymphocyte globulin for immunosuppression in renal allograft recipients.

Nineteen of 224 renal allograft recipients who were prospectively randomized to receive either cyclosporine (n = 117) or azathioprine sodium-antilymphocyte globulin (n = 107) for immunosuppression suffered from one period of pneumonia (14 azathioprine and five cyclosporine recipients); two recipients of azathioprine had two episodes. Four patients in the azathioprine group and one in the cyclosporine group died, for mortalities of 3.7% and 0.85%, respectively. The percentage of pneumonia-free patients at one year was 96.3% in the cyclosporine group while it was 90.8% in the azathioprine group. Nondiabetics, women, and recipients of grafts from living related donors were at a statistically lower risk of developing pneumonia when treated with cyclosporine. Viral (cytomegalovirus), fungal (Candida, Aspergillus), and multibacterial causes of pneumonia each occurred with a similar incidence.

Sickle cell trait: possible contributory cause of renal allograft failure.

A black male with known sickle cell trait (hemoglobin AS) received two cadaveric renal transplants in succession. After excellent initial graft function he had what appeared clinically to be an acute rejection episode which could not be reversed by immunosuppressive therapy on either occasion. The histopathology of the removed allografts did not reveal a picture of acute rejection, but instead revealed extensive intravascular sickling of the erythrocytes. This is important especially for the transplant centers in the United States which may have a significant number of the black population among the renal allograft recipients.