The effect of heme-linked ionizable groups on cyanide binding to methemoglobin

The pH dependence of the kinetics of the binding of cyanide ion to methemoglobins A and S and to guinea pig and pigeon methemoglobins appears to be not directly correlated with the net charges on the proteins. The kinetics can, however, be adequately explained in terms of three sets of heme-linked ionizable groups with pK1 ranging between 4.9 and 5.3, pK2 between 6.2 and 7.9, and pK3 between 8.0 and 8.5 at 20 degrees C. pK1 is assigned to carboxylic acid groups, pK2 to histidines and terminal amino groups, and pK3 to the acid-alkaline methemoglobin transition. Kinetic second order rate constants have also been determined for the binding of cyanide ion by the four sets of methemoglobin species present in solution. The pKi values and the rate constants of methemoglobin S are strikingly different from those of methemoglobin A. This result is explained in terms of different electrostatic contributions to the free energy of heme linkage arising from differences in the environments of ionizable groups at the surfaces of the two molecules.     

Occurrence of latent virus infection in visually-rated cowpea (Vigna unguiculata L. Walp) seedlings

Abstract

The presence of latent infections was studied in five cowpeas varieties. Seeds of the varieties were planted and the seedlings inoculated with antigens from Cucumber mosaic virus (CMV) genus Cucumovirus, Bean common mosaic virus (BCMV) genus Potyvirus (Blackeye cowpea mosaic virus strain), Southern bean mosaic virus (SBMV) genus Sobemovirus and Cowpea mottle virus (CPMoV) genus Carmovirus seven days after planting. Seedlings expressing symptoms were rouged at two weeks after inoculation, while asymptomatic ones were subjected to serological indexing to detect the presence/absence of latent infection. Protein A-sandwich enzyme-linked immunosorbent assay (PAS ELISA) was employed for the serological detection of CMV, SBMV and CPMoV, while antigen-coated plate (ACP) ELISA was used to detect BCMV in the asymptomatic plants. Cowpea seedlings without virus symptoms but with positive serological reactions were considered as being latently infected. All of the inoculated TVu 1272 and SuVita-2 plants showed symptoms consistent with CMV and CPMoV infections, respectively. The rate of CMV latent infection was high in TVu 1179 (14.5%), low in SuVita-2 (1.3%) but not recorded in TVu 1272.     

Response of cowpea bruchid,Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae) to cheese wood,Alstonia boonei De Wild stem bark oil extracted with different solvents

Cheese wood, Alstonia boonei De Wild stem bark was extracted with five different solvents namely: methanol, ethanol, acetone, petroleum ether and n-hexane. The extracts were tested for insecticidal activity on cowpea bruchid, Callosobruchus maculatus (Fab.). Adult mortality and adult emergence of the insects were investigated. Oviposition deterrences using dual-choice and multiple-choice tests were also investigated as well as percentage damage and weight loss at temperature of 28?±?2?°C and 75?±?5% relative humidity. Results showed that at the rate of 2% extract per 20?g of cowpea seeds, methanol, petroleum ether and n-hexane extracts caused 100% mortality of adult cowpea bruchid after four?days of post treatment. When the bruchid had choice of oviposition substrate, they laid significantly (p?<?0.05) fewer eggs on cowpea seeds treated with extracts compared to untreated seeds. There was no adult emergence in seeds treated with methanol, ethanol, petroleum ether and n-hexane extracts and 100% reduction in F₁ progeny was recorded compared with untreated that had 81.86% adults emergence and 0% reduction in F₁ progeny. The results obtained from this study revealed that methanol, ethanol, acetone, petroleum ether and n-hexane extracts of A. boonei stem bark were effective in controlling C. maculatus and could serve as an alternative to synthetic insecticides for the protection of stored cowpeas against bruchids.     

Intestinal helminthiases and schistosomiasis among school children in an urban center and some rural communities in southwest Nigeria

Intestinal helminths and schistosomiasis among school children were investigated in an urban and some rural communities of Ogun State, southwest Nigeria. Fecal samples of 1,059 subjects (524 males, 535 females) aged 3-18 years were examined using direct smear and brine concentration methods between June 2005 and November 2006. The pooled prevalence of infection was 66.2%. Ascaris lumbricoides showed the highest prevalence (53.4%) (P < 0.001) followed by hookworms (17.8%), Trichuris trichiura (10.4%), Taenia sp. (9.6%), Schistosoma mansoni (2.3%), Strongyloides stercoralis (0.7%), Schistosoma haematobium (0.6%), and Enterobius vermicularis (0.3%). The prevalences of A. lumbricoides, hookworms, Taenia sp., S. mansoni, and S. stercoralis in the urban centre were similar (P > 0.05) to those in the rural communities. The fertile and infertile egg ratios of A. lumbricoides in the urban centre and the rural communities were 13: 1 and 3.7: 1, respectively. Each helminth had similar prevalences among both genders (P > 0.05). The prevalence of A. lumbricoides increased significantly with age (P < 0.001). The commonest double infections were Ascaris and hookworms, while the commonest triple infections were Ascaris, hookworms, and Trichuris. The study demonstrates the need for urgent intervention programmes against intestinal helminthiases and schistosomiasis in the study area.     

Fungi isolated from skins and pens of healthy animals in Nigeria

The mycoflora of 220 skin scrapings, hair, nail samples and pens’ materials of apparently healthy animals including cows, sheep, goats, rabbits, pigs and dogs were determined. Twenty eight species of fungi belonging to ten genera were recovered. Chrysosporium spp. were the most common and C. keratinophilum was recovered from all animals. Dermatophytes which are known causal agents of dermatophytosis were also isolated indifferent frequencies (Microsporum gypseum, M. canis, Trichophytonmentagrophytes, T. rubrum). This revised version was published online in June 2006 with corrections to the Cover Date.     

Extracellular amylase production by cassava-fermenting bacteria

Summary Fermentation of cassava tubers was accompanied by a gradual decrease in pH, increased amylase activity in the steep liquor, and increased microbial load and lactic acid concentration. Amylase-producing bacterial strains associated with cassava fermentation were isolated and identified asBacillus subtilis, Bacillus licheniformis andBacillus cereus. The pH optima for the partially purified enzymes of these organisms were 7.0, 5.5 and 7.5, whilst their temperature optima were 30, 37 and 80°C. There was no significant difference in amylase activities when starch, dextrin, amylopectin, glucose and maltose were used as growth substrates.     

Reproductive bionomics of the soft tick, Ornithodoros turicata (Acari: Argasidae)

The effects of different temperatures and relative humidities (RHs) were tested on various reproductive parameters of Ornithodoros turicata, an argasid tick that inhabits gopher tortoise burrows in Florida, USA. The pre-oviposition, oviposition and incubation periods of the ticks decreased as temperature increased. These periods were also affected by the RH. The number of eggs oviposited was affected significantly by the combined effect of temperature and RH. Fewer eggs were laid by ticks in the 24°C regimes and the 27°C/95%RH regime compared to those in the other temperature/RH groups. There was an inverse relationship between the number of eggs oviposited and the percentage of hatched larvae that was correlated with the temperature and RH. Ticks reared at 27°C/90%RH and 30°C/90%RH laid more eggs than those reared in the other combinations of temperature and humidity but fewer larvae hatched from these eggs. The reproductive fitness index (RFI) values were highest in females held in the 24°C groups and the 30°C/95%RH group, although significantly more larvae hatched at the lower temperatures. The optimum reproductive conditions for O. turicata under laboratory conditions appear to be 24°C and 90–95%RH. While mating occurred at all temperatures, none of the females laid eggs at 22°C. The ticks may move preferentially to low temperatures when not feeding to remain above the critical equilibrium humidity and/or below the critical metabolic level necessary for prolonged survival. However, most female ticks oviposited after 45 days when moved to 27°C/95%RH. Ornithodoros turicata females may have a limited capability to delay oviposition until an optimal microenvironment for egg deposition can be located in the burrow.     

Screening and molecular identification of potential probiotic lactic acid bacteria in effluents generated during ogi production

Screening and molecular identification of probiotic lactic acid bacteria (LAB) in effluents generated during the production of ogi, a fermented cereal (maize, millet, and sorghum) were done. LAB were isolated from effluents generated during the first and second fermentation stages in ogi production. Bacterial strains isolated were identified microscopically and phenotypically using standard methods. Probiotic potential properties of the isolated LAB were investigated in terms of their resistance to pH 1.5 and 0.3% bile salt concentration for 4 h. The potential LAB isolates ability to inhibit the growth of pathogenic organisms (Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium) was evaluated in vitro. The pH and LAB count in the effluents ranged from 3.31 to 4.49 and 3.67 to 4.72 log cfu/ml, respectively. A total of 88 LAB isolates were obtained from the effluents and only 10 LAB isolates remained viable at pH 1.5 and 0.3% bile salt. The zones of inhibition of the LAB isolates with probiotic potential ranged from 7.00 to 24.70 mm against test organsisms. Probiotic potential LAB isolates were molecularly identified as Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus reuteri, Enterococcus faecium, Pediococcus acidilactici, Pediococcus pentosaceus, Enterococcus faecalis, and Lactobacillus brevis. Survival and proliferation of LAB isolates at low pH, 0.3% bile salt condition, and their inhibition against some test pathogens showed that these LAB isolates could be a potential probiotics for research and commercial purposes.     

Mycotoxins of fungal strains from stored herbal plants and mycotoxin contents of Nigerian crude herbal drugs

The ability of fungi isolated from stored herbal drug plants to produce mycotoxins in semisynthetic media was studied. The results obtained show that aflatoxins and ochratoxin A, were produced by Aspergillus flavus, A. parasiticus and A. ochraceus isolates. The time-production courses of aflatoxins B₁, B₂, ₁ and ochratoxin A in crude herbal drug preparations show that more of these toxins were produced with increase in time of storage of the drugs. The results indicate that the potential exists for the toxigenic strains to elaborate mycotoxins in a large quantity in herbal drug substrates than in semisynthetic media.This revised version was published online in October 2005 with corrections to the Cover Date.     

Systematic Review and Meta-Analysis of Tacrolimus versus Ciclosporin as Primary Immunosuppression After Liver Transplant

MethodsSearches of PubMed, the Cochrane Library and EMBASE identified RCTs of tacrolimus and ciclosporin as the immunosuppressant in adult primary liver transplant recipients, published between January 2000 and August 6, 2014. A random effects meta-analysis was conducted to evaluate the relative risk of death, graft loss, acute rejection (AR), new-onset diabetes after transplantation (NODAT) and hypertension with tacrolimus relative to ciclosporin at 12 months.ResultsThe literature search identified 11 RCTs comparing ciclosporin with tacrolimus. Relative to ciclosporin, tacrolimus was associated with significantly improved outcomes in terms of patient mortality (risk ratio [RR] with ciclosporin of 1.26; 95% confidence interval [95%CI] 1.01–1.58). Tacrolimus was superior to ciclosporin in terms of hypertension (RR with ciclosporin 1.26; 95%CI 1.07–1.47), but inferior in terms of NODAT (RR with ciclosporin 0.60; 95%CI 0.47–0.77). There were no significant differences between ciclosporin and tacrolimus in terms of graft loss or AR.ConclusionsMeta-analysis of RCTs published since 2000 showed tacrolimus to be superior to ciclosporin in terms of patient mortality and hypertension, while ciclosporin was superior in terms of NODAT. No significant differences were identified in terms of graft loss or AR. These findings provide further evidence supporting the use of tacrolimus as the cornerstone of immunosuppressive therapy in liver transplant recipients.