PCR-based identification of Bacillus thuringiensis isolated from soil samples in Nigeria.

Six isolates of Bacillus thuringiensis isolated from soil samples confirmed to be toxic to mosquito larvae were differentiated using a PCR-Based technique. Three of these isolates initially identified using a serological technique were further differentiated with the PCR amplification of the delta-endotoxin target sequences. Using the total DNA of isolates as template, at least four isolates yielded amplicons one or all the crystal protein genes, cryI a, b, c, or II with sizes ranging from 238-1070 bp. None of these isolates yielded an amplicon for any of Cry IV A, B and D tested. Of the four isolates identified by PCR technique one isolate remained unidentified by serology.

Isolation and characterization of the exo-enterotoxin of Vibrio cholerae strain 110 Cal.

Vibrio Cholerae "strain 110 Cal" from Calabar, Nigeria were grown in syncase broth. Exo-enterotoxin secreted into the medium was then isolated purified and characterized. The toxin had enterotoxic activity using the infant mouseassay of World Health Organization. The toxin also had a molecular weight of about 89,000 daltons by gel filtration through sephadex G-150 and 100,000 daltons by polyacrylamide gel electrophoresis (PAGE). The toxin exhibited two subunits with molecular weights of about 63,000 and 31,000 daltons on SDS-PAGE. The toxin was resolved through sephadex G-150 into three peaks having molecular weights of about 89,000, 44,000 and 14,000 daltons respectively. The three peaks had enterotoxic activity. Each peak contained a single protein band on PAGE and SDS-PAGE showed that peak I consisted of two subunits with molecular weights of 56,000 and 31,000 daltons and peak II and III were monomers.

Cloning and characterization of the tetracycline resistance determinant from enteropathogenic Escherichia coli p1479.

As part of an epidemiological study, R plasmids coding for tetracycline resistance were isolated from enteropathogenic Escherichia coli. A 1.4kb Pst 1 fragment of one of them p1479 (size 5.7kb) has been cloned into plasmid pGL101. This recombinant plasmid containing the tetracycline gene was then transformed into E. coli DHI where the tetracycline resistant gene was fully expressed. Attempts to develop this clone to a diagnostic probe is now in progress.

Effect of oral contraceptive agents (OCA) on the distribution; mobilisation and utilisation of vitamin A and E in rats fed specified Nigerian diet

In this study; the effects of oral contraceptive agents (OCA) on vitamin A and E metabolism in rats were examined. Two combined type (OCA) ovral and nordette and their pure components (ethinylestradiol plus norgestrel and ethinylestradiol plus levonorgestrel) were administered at different doses separately to young female albino rats fed a Nigerian diet for a period of 60 days. Plasma vitamin A and plasma retinol binding protein (PRBP) levels were found to be higher in OCA treated rats compared to control rats. Also OCA markedly raised the liver vitamin A depletion rate and the rate of utilisation of the vitamin. Decrease in liver or cellular retinol binding protein (CRBP) was also observed; suggesting that rats given OCA had a higher vitamin A requirement level. OCA decreased the plasma concentration of vitamin E for the first 30 days of administration. However an increase in concentration of plasma vitamin E was observed in the last 30 days of administration of the pills

Study of plasmid screening amongst pathogenic bacteria isolated in Nigeria.

Clinical isolates of Neisseria gonorrhoeae, Campylobacter jejuni, Escherichia coli, Shigella dysenteriae, Shigella boydii, Yersinia spp. and Salmonella spp. were screened for the presence of plasmids. Approximately 80% of these strains harboured plasmids ranging in molecular weight from 1.0 to 45 x 10(6) daltons.

Antimicrobial resistance patterns and plasmids of enteropathogenic Escherichia coli isolated in Nigeria.

In an epidemiological study of enteropathogenic Escherichia coli, 102 strains were isolated from patients seen at the University Teaching Hospital in Lagos. The most common serotype encountered was 055 followed by 026. Antimicrobial susceptibility testing and plasmid profiling of the strains were done. All the strains were sensitive to colistin, nalidixic acid, nitrofurantoin, cefotaxime, amikacin, and augmentin. Of the 102 strains, 47 (46%) were resistant to one or more of the following antimicrobial agents: Co-trimoxazole, tetracycline, ampicillin, streptomycin, sulphonamide and a combination of ampicillin with sulbactam. All the strains that were resistant to any antimicrobial agents were also resistant to tetracycline. Seventy-two strains (70.6%) harbored plasmid whose molecular weights ranged from 0.8 to 120 x 10(6) daltons. The majority of the plasmid were smaller than 6 x 10(6); 90% of strains carrying plasmid ranging in size from 2 to 6 x 10(6) daltons and 50 to 70 x 10(6) daltons were resistant to one or more antimicrobial agents. Transformation and conjugation experiment showed that about 57% of the resistant strains carried R plasmid. Plasmid-determined resistance to tetracycline, ampicillin, streptomycin and sulphonamide was found.

A calcium dependent endoribonuclease from Trypanosoma congolense cytoplasm.

A major endoribonuclease whose activity depends on the presence of calcium ions was isolated from the cytoplasm of Trypanosoma congolense. Like the Ca2+-dependent endoribonuclease of T. brucei cytoplasm, this enzyme degraded poly(A) preferentially but also degraded to a lesser extent poly(U), tRNA and rRNA to give 5'-phosphoribosyl oligonucleotides. Neither enzyme hydrolyzes poly(G) or DNA. Both ribonucleases are inhibited by polyanions and heavy metal ions, and are heat-labile; N-ethylmaleimide has no effect on either activity. However, unlike the Ca2+-RNase of T. brucei cytoplasm, this endoribonuclease is also stimulated by Mg2+, acts maximally at around pH 8.9, and is virtually inactivate towards poly(C). It is inhibited by iodoacetamide but unaffected by spermine. Its molecular weight is about 42 000 as determined by gel filtration.

Studies on the mechanism of adenosine transport in Trypanosoma vivax.

Adenosine uptake in the presence of some metabolic inhibitors and nucleosides has been studied. The uptake of adenosine was inhibited by oubain, phlorizin, iodoacetate and coformycin. Guanosine, on the other hand stimulated adenosine uptake to a considerable extent. Neither thymidine nor inosine caused significant change in adenosine uptake. Results of the time course assay and uptake studies at various concentrations of adenosine suggest that possibly more than one mode of uptake operates in the transport of adenosine in T. Vivax.

Studies on the catalytic properties of the calcium-dependent endoribonuclease of Trypanosoma brucei cytoplasm.

A calcium-dependent endoribonuclease isolated from Trypanosoma brucei cytoplasm has been further characterized. The products of exhaustive endonuclease digestion of poly(A), which the enzyme cleaved preferentially, were small oligonucleotides terminated by a 5'-phosphoryl group. Its apparent Km value was 0.8 mM using poly (A), and 3.3 mM using transfer RNA. The base specificity of the endoribonuclease was further verified by using synthetic heteropolyribonucleotides as substrates. The enzymatic reaction was inhibited by polyamines, polyanions, iodoacetic acid and the heavy metals, but only very slightly by N-ethylmaleimide and iodoacetamide. A possible implication of the enzyme in the turnover of messenger RNA is discussed.

A novel extracellular proteinase from Bacillus pumilus.

Bacillus pumilus NCTC AII6/73 produces a novel extracellular alkaline proteinase whose optimum is pH 9.5. The purified product from ion-exchange chromatography (DEAE-cellulose) was resolved into two bands by polyacrylamide-sodium dodecyl sulphate (SDS) gel electrophoresis. These had approximate molecular weights of 15.6 x 10(3) daltons, respectively, and a high content of glycine and proline, comprising roughly 50% of the total amino residues.

Biochemical frontiers of fibrosis: concepts and perspectives.

The inhibition of Fibrotic lesion are classified into two: specific and nonspecific inhibition. The specific inhibition is based on the chemistry and metabolism of collagen, whereas the nonspecific inhibition is viewed from the point of the fibro-proliferative inflammation preceding fibroblasts activation. A brief account is given on existing as well as perspective methods to present a frame work for a concept on pharmacology of fibrosis.

Antibacterial activity of extracts from some African chewing sticks.

The antibacterial activity of aqueous, isobutanol, and benzene extracts of five popular African chewing sticks was studied by the agar ditch plate method. The isobutanol extract produced the greatest antimicrobial activity, and the benzene extract the least. Streptococci were the most sensitive to the extracts, while Escherichia coli was the most resistant. It would appear that the active principles of the various chewing-stick extracts are not the same and that the extract from a given chewing stick is chemically heterogeneous. It is suggested that the regular use of the African chewing stick, acting as an antiseptic, may control the formation and activity of dental plaque and therefore reduce the incidence of gingivitis and possibly dental caries.

Biochemical studies of acetylcholine esterase inhibitor present in Eugenia caryophyllus.

Water, saline and ethanol extracts of Eugenia caryophyllus inhibited brain acetylcholinesterase (AchE) activity. Inhibitory action of the saline extract was greater than that of other extracts. The most active fraction of the saline extract obtained by chromatography through Sephadex G25 and DEAE cellulose columns and elution with tris and phosphate buffers (pH. 7.1) exhibited reactions characteristic of phenols, amino compounds and uronic acid. It is, therefore, suggested that the active inhibitor is a complex glycoside containing phenol and uronic acid part structure.

Effect of aqueous extract of Eugenia caryophyllus on brain acetylcholine esterase in rats.

The effect of aqueous extract of Eugenia caryophyllus on brain acetylcholine esterase (AChE) activity in rats was studied. Results indicate that the aqueous extract reduced the hydrolysis of acetylcholine (ACh) by AChE. This reducing effect was not due to the acidic nature of the extract and suggests that Eugenia caryophyllus contains some water soluble substance(s) with anti-choline esterase activity.