Showing papers by "Rivers State University of Science and Technology published in 1989"

Occurrence of drug-resistant bacteria in communal well water around Port Harcourt, Nigeria.

Abstract: A total of 108 raw water samples was collected from 36 wells at nine shanty settlements around Port Harcourt, Nigeria, over a period of 7 months. Samples were analysed for their bacteriological quality. Selected bacterial strains isolated from the samples were tested for their susceptibility to ten commonly used antibiotics. The organisms isolated include Pseudomonas spp., Klebsiella spp., Staphylococcus spp., Proteus spp., Enterococcus faecalis, Aeromonas spp., Escherichia coli, Chromobacterium spp., Flavobacterium spp., and Serratia spp. Out of 300 strains tested, 23 (6.9%) were susceptible to all the antibiotics, 277 (92.3%) were resistant to at least one antibiotic and 232 (77.3%) were resistant to two or more antibiotics. The epidemiological significance of these results is discussed.

The susceptibility of pepper fruits (Capsicum species) to oviposition by the pepper fruitfly, Atherigona orientalis (Schiner) in Port Harcourt, Nigeria

Abstract: Atherigona orientalis (Schin.) is a dipterous pest of pepper fruit in Nigeria. Field and laboratory observations showed that available local varieties of pepper were infested by the developmental stages during the rainy season in Port Harcourt. The fruits were contaminated with pupae and larval frass. The population of the various stages are primarily related to the availability of susceptible pepper fruits, itself determined by rainfall. Of four local varieties, Nsukka Yellow (Capsicum annum) was most preferred and Bird's eye chilli (C. frutescens) the least preferred by A. orientalis.

The biology of Sylepta derogata Fabricius (Pyralidae), a lepidopterous pest of okra in eastern Nigeria.

Abstract: The biology of Sylepta derogata Fabricius was studied in the laboratory. The number of larval instars varied from 5 to 6 when fed singly. The larva possesses three pairs of thoracic legs and four abdominal prolegs. Among morphological differences between the instars, the most striking between the 1st and 2nd instars was the presence on the 2nd of two brown spots on the dorsal aspect of the prothoracic segments. Other instars were differentiated by the size and shape of the shields. The pupa is obtect and conical in shape with ten abdominal segmants, distinctly separated except the 9th and 10th segments. The genital pore occurs ventrally below the 8th abdominal segment in the female and in the male on the 9th segment. The abdomen of the male is more slender than that of the female. The life cycle was completed in 33.9 ± 0.5 days.

Alteration of glucose-6-phosphatase activity and regenerative, and total DNA concentrations in regenerating and normal rat liver of aqueous extracts of two Nigerian plants.

Abstract: The effect(s) of an intraperitoneal (i.p.) administration of aqueous extracts of two Nigerian medicinal plants, Garcina cola and Vermonia amygdalina on the level of glucose-6-phosphatase activity, total protein content and regenerative and total DNA concentrations, was determined in liver homogenates of partially-hepatectomized and normal albino rat liver. The established control curves for the DNA and microsome syntheses rates after partial hepatectomy showed two waves of synthetic activity; the first occurring at 24 hrs., and the second at 32 hrs as judged by total regenerative DNA concentration and glucose-6-phosphatase activity. Garcina cola significantly inhibited the first wave of microsome and DNA syntheses by 31% and 24% respectively in a dose-related manner. However, the degree of inhibition of glucose-6-phosphatase activity by Garcina cola was substantially reduced in normal rat liver when administered simultaneously with carbon tetrachloride. Dilute and concentrated extracts of Vermonia amygdalina, on the other hand, elevated the levels of glucose-6-phosphatase activity in normal rat liver by 44% and 54%, respectively over the controls. Total DNA concentration was similarly increased, though to a lesser degree. The implication of these results are discussed in relation to the structural similarity of the furocoumarins contained in these plants to AFB1, and their likely modes of action.

Planning for coastal zone management programme in Nigeria

Abstract: The coastal zone in Nigeria has some problems and if both the Federal and the State Governments continue their movements away from viewing the coastal zone as an important and ecologically unique and fragile environment, the problem will retard the resources of the area. Developing countries like Nigeria lag behind the developed world in the provision of legislations to protect their citizens, coastal environment, and companies and firms. Presently, the development of Nigeria strictly comes from the coastal zone, therefore Government at all levels must be brought to see the coastal zones as a district and important region, and to provide a CZMP network capable of successfully resolving the issues particular to it.

On the integral equation method for radiative transfer past a rotating plate in unsteady flow

Abstract: The transient effect on the flow of a thermally-radiating and electrically-conducting compressible gas in a rotating medium bounded by a vertical flat plate, is studied when the radiative flux satisfies the exact integral expression. The transience is provoked by a time-dependent perturbation on a constant plate temperature. The solution is constructed for the flow near and away from the plate by the Laplace transform method. The results are compared with the recent work of Bestman and Adjepong (1988).

Porosity and permeametry at sub-atmospheric pressures

Abstract: The Carman-Kozeny equation is applicable in the viscous flow regime but, as the powder becomes finer, this equation fails. The controlling factor is the ratio of the hydraulic diameter to the mean free path of gas molecules (rH/λ) and, as this approaches unity, “slip flow” occurs. This effect increases with (a) increasing fineness, i.e. rH reduced, (b) decreasing porosity, i.e. rH reduced, and (c) decreasing pressure, i.e. λ increased. In order to account for the enhanced flow arising as a result of this failure, a second term is introduced into the equation and this includes an unknown “constant” (δK0/K), the coefficient of slip. It was considered probable that this so-called constant was a function of (rH/λ), and an attempt was made to investigate this relationship.

New media for the isolation ofDermatophilus congolensis

Abstract: Two inhibition media comprising combinations of colistin methanesulphonate, nalidixic acid, nystatin and malachite green were developed for the isolation of Dermatophilus congolensis. Dermatophilosis is seasonally prevalent in Nigeria in the rainy months of April to November. The slow growth of D. congolensis the causal organism allows faster proliferating organisms to mask their presence on culture media thereby making it very difficult to isolate. Ahu-Samra and Walton (1977) successfully developed a standard inhibition medium by incorporating 1,000 iu/ml of polymyxin B sulphate into brain heart infusion agar. Earlier fruitful attempts, though not as good, were reported by Abu-Samra, Imbabi and Mahgoub (1970) and Cruz (1974). The possibility of developing superior inhibition media was the main purpose of the experiments described here. The agents were added into agar in the following two combinations: 1. Nalidixic acid--10/~g/ml, malachite green---0-25#g/ml and nysta t in~ 200 i#/ml. 2. Colistin methanesulphonate--100i#/ml, nalidixic acid---10#g/ml and nystatin--200 i# /ml. Brain heart infusion (BHI) broth cultures of D. congolensis which had been incubated for 48 hours were machine agitated, to give a uniform suspension, and 10-fold serial dilutions from 10 -1 to 10 -1°, prepared in normal saline. The diluted broth cultures were subcultured onto BHI agar plates and the number of colonies present after 24, 48 and 72 hour incubation counted. One gram of soil sample was suspended in 10 ml of sterile water from which 10-fold dilutions were prepared. One ml from each of the D. congolensis broth dilutions after thorough agitaton was mixed with 9 ml of 10 -s soil dilution. A drop from each mixture of D. congolensis and soil suspension (10 -5 soil dilution + D. congolensis broth dilutions) was cultured in quintuplets on plates containing each of the two inhibition media under test. The plate count of D. congolensis was 3,500,000 colony forming units (cfu)/ml of broth culture diluted 10-L Plate cultures of D. congolensis in soil suspensions showed the following patterns of inhibitions and isolations in the two media used: In medium No. 1 there were numerous colonies of D. congolensis on plates inoculated with broth cultures at dilutions of 10 -~ and 10 -2 with no contaminants present. In medium No. 2 there was one cfu of soil organisms on one plate after 24 hours and two cfu of soil organisms on another plate after 48 hours. There were many cfu of D. congolensis on plates inoculated with 10 t and 10 -2 broth dilutions but only one cfu was apparent after 48 hours on plates inoculated with 10 -4 dilution of broth culture. The above observations indicated that the two media were capable of totally or sufficiently suppressing the growth of soil contaminants while allowing D. congolensis to grow in isolated colonies, from which it could be subcultured in pure forms onto fresh plates.