Io Kibwage

Separation of erythromycin and related substances by high-performance liquid chromatography on poly(styrene-divinylbenzene) packing materials.

A comparative evaluation of three brands of poly(styrene-divinylbenzene) copolymers, Hamilton PRP-1 (10 micron), Rogel (8 micron) and TSK-Gel (10 micron), as column packing materials for high-performance liquid chromatographic separation of erythromycins is presented. Erythromycins A, B and C, anhydroerythromycin A, erythromycin A enol ether, N-demethylerythromycin A, anhydro N-demethylerythromycin A and N-demethylerythromycin A enol ether were chromatographed. The effects of column temperature, concentration of organic modifier in the mobile phase, concentration of phosphate buffer, the addition of quaternary ammonium salts and pH are described. The best separations were obtained on TSK-Gel with the mobile phase acetonitrile-methanol-0.2 M tetramethylammonium hydroxide pH 8.0-0.2 M phosphate buffer pH 8.0-water (30:15:25:5:25). PRP-1 and Rogel gave equally good separations but with higher retention volumes.

Optimization of the separation of erythromycin and related substances by high-performance liquid chromatography☆

An improved high-performance liquid chromatographic method for analysis of erythromycin is described. The separation can be performed under mild conditions of pH (6.5) and temperature (35 degrees C) on C8 and C18 silica-based reversed-phase materials of different origins. The mobile phase, with a flow-rate of 1.5 ml/min, contained various amounts of acetonitrile (25-40%, v/v), 5% (v/v) 0.2 M ammonium phosphate buffer pH 6.5, 20% (v/v) 0.2 M tetramethylammonium phosphate and water. UV detection at 215 nm allows quantitation of erythromycins A, B and C, N-demethylerythromycin A, erythromycin A enol ether and anhydroerythromycin A. The column history plays a major role, older columns often giving better separations.

Antibacterial activities of erythromycins A, B, C, and D and some of their derivatives.

The MICs of erythromycins A, B, C, and D and some of their derivatives were determined against 21 gram-positive and 15 gram-negative microorganisms. Antibacterial activity was confined to gram-positive and very few gram-negative bacteria. Erythromycin B was somewhat less active than erythromycin A, and erythromycin C and D showed about half that activity or even less. Most other derivatives had negligible activity. Determination of potency by diffusion and turbidimetric assays were in line with MICs. The examination of the results of these assays, however, revealed that there are differences between the data of different laboratories, depending on the microorganisms and conditions used.

Isolation of erythromycins and related substances from fermentation residues of streptomyces erythreus by high-performance liquid chromatography on silica gel

Abstract Preparative high-performance liquid chromatography on silica gel allows the isolation of erythromycins and related substances from mother-liquor concentrates. Three mobile phases were used consecutively: A, ethyl acetate—methanol—25% ammonia (100:8:1, v/v); B, diethyl ether—methanol—25% ammonia (100:7:1, v/v) and C, dichloromethane—methanol—25% ammonia (100:5:0.5, v/v). The separation and purification was confirmed by thin-layer chromatography. Thirteen pure substances were isolated among which are erythromycins A, B, C and D, 8,9-anhydroerythromycin A-6,9-hemiketal, erythromycins A and C-6,9;6,12-spiroketals and N-demethylerythromycin A-6,9;9,12-spiroketal.

Use of mobile learning technology among final year medical students in Kenya

Introduction Mobile phone penetration has increased exponentially over the last decade as has its application in nearly all spheres of life including health and medical education. This study aimed at assessing the use of mobile learning technology and its challenges among final year undergraduate students in the College of Health sciences, University of Nairobi. Methods This was a cross-sectional descriptive study conducted among final year undergraduate students at the University of Nairobi, College of Health Sciences. Self-administered, anonymous questionnaires were issued to all final year students in their lecture rooms after obtaining informed consent. Data on demographics, mobile device ownership and mobile learning technology use and its challenges was collected. Data entry and analysis was done using SPSS®. Chi-square and t-test were used for bivariate analysis. Results We had 292 respondents; 62% were medical students, 16% were nursing students, 13% were pharmacy students and 9% were dental surgery students. The majority were female (59%) and the average age was 24 years. Eighty eight percent (88%) of the respondents owned a smart device and nearly all of them used it for learning. 64% of the respondents used medical mobile applications. The main challenges were lack of a smart device, lack of technical know-how in accessing or using apps, sub-optimal internet access, cost of acquiring apps and limited device memory. Conclusion Mobile learning is increasingly popular among medical students and should be leveraged in promoting access and quality of medical education.

Thin-layer chromatographic study of the metabolites of erythromycins in the wistar rat

The metabolites of erythromycin A, anhydroerythromycin A, N-demethylerythromycin A and erythromycin B in the Wistar rat were studied by thin-layer chromatography. In some experiments germ-free rats, rats with a cannulated bile duct and a gastrectomized rat were used. The erythromycins examined were shown to undergo two principal changes, N-demethylation and acid-catalysed degradation. It was demonstrated that the stomach and the liver are not the sole sites of acid degradation and demethylation of erythromycins, respectively. Erythromycin A gives three principal metabolites, anhydroerythromycin A, anhydro-N-demethylerythromycin A and N-demethylerythromycin A, and erythromycin A enol ether and N-demethylerythromycin A enol ether are present to a minor extent. 5-O-Desosaminylerythronolide A was also identified, suggesting the presence of an erythromycin glycosidase.

Essential oil of cymbopogon winterianus jowitt from Tanzania: Composition and antimicrobial activity

Abstract The hydro-distilled essential oil (1.6%) of fresh aerial parts of wild Cymbopogon winterianus Jowitt was analyzed by GC-MS. Fifty compounds representing 96.5% of the oil were identified. The main components of the oil were linalool (27.4%), citronellol (10.9%), geraniol (8.5%), α-calacorene, cis-calamenene (4.3%), β-elemene (3.9%) and longifolene (3.5%). The oil exhibited low antimicrobial activity.

Tissue distribution and excretion of radioactively labelled compounds in the Wistar rat after administration of [N-methyl-14C]-erythromycin A

SummaryTissue distribution and excretion of radioactively labelled compounds was studied in the Wistar rat after i.v. administration of [N-methyl-14C]-erythromycin A. Whole-body autoradiography and liquid scintillation counting was used to investigate the tissue localization of radioactivity in pregnant and non-pregnant rats. Tissue levels were maximal within 20 min, except for lachrymal glands, thymus and brain. Large amounts of radioactively labelled compounds, partly originating from active secretion, were present in the small intestine and caecum. Marked concentration of radioactively labelled compounds was also observed in the liver, spleen, lachrymal and salivary glands, lymph nodes, mammary glands, skin, bone marrow, and, to a lesser extent, in the lung, kidney and skeletal muscle. During six hours of experimental follow-up, plasma levels remained lower than corresponding tissue levels. At 1 h the radioactivity in fetuses was about three times lower than that in maternal blood.Within 48 h, more than 90% of the administered radioactivity was excreted. The amounts of radioactivity recovered in urine, faeces and expired air were about 19%, 48% and 24% respectively. After 48 h, 8% of the administered radioactivity was found in the carcass.

Building capacity in implementation science research training at the University of Nairobi

BackgroundHealth care systems in sub-Saharan Africa, and globally, grapple with the problem of closing the gap between evidence-based health interventions and actual practice in health service settings. It is essential for health care systems, especially in low-resource settings, to increase capacity to implement evidence-based practices, by training professionals in implementation science. With support from the Medical Education Partnership Initiative, the University of Nairobi has developed a training program to build local capacity for implementation science.MethodsThis paper describes how the University of Nairobi leveraged resources from the Medical Education Partnership to develop an institutional program that provides training and mentoring in implementation science, builds relationships between researchers and implementers, and identifies local research priorities for implementation science.ResultsThe curriculum content includes core material in implementation science theory, methods, and experiences. The program adopts a team mentoring and supervision approach, in which fellows are matched with mentors at the University of Nairobi and partnering institutions: University of Washington, Seattle, and University of Maryland, Baltimore. A survey of program participants showed a high degree satisfaction with most aspects of the program, including the content, duration, and attachment sites. A key strength of the fellowship program is the partnership approach, which leverages innovative use of information technology to offer diverse perspectives, and a team model for mentorship and supervision.ConclusionsAs health care systems and training institutions seek new approaches to increase capacity in implementation science, the University of Nairobi Implementation Science Fellowship program can be a model for health educators and administrators who wish to develop their program and curricula.

Evaluation of tetracycline raw materials and finished products found on the Kenyan market

Contents of tetracycline, its degradation products (epitetracycline, epianhydrotetracycline, anhydrotetracycline) and a fermentation impurity (2-acetyl-2-decarboxamidotetracycline) were determined in four raw materials, 12 batches of six ointment products, four eye ointment products and nine batches of five capsule products, all sampled from the Kenyan market. The analytical method was liquid chromatography on a column packed with a poly(styrenedivinyl-benzene) material (8-microns PLRP-S 100 A). All raw materials and finished products had tetracycline contents and impurity levels within the prescribed compendial limits.