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Biomedical subjects

M E Hawkins

Publications and source records attributed to M E Hawkins.

7 recordsLinked to original sources
PubMed1992

Clinical pharmacology of 2',3'-dideoxyinosine in human immunodeficiency virus-infected children.

The pharmacokinetics of intravenous and oral 2',3'-dideoxyinosine (ddI) and the relationships between pharmacokinetic parameters and measures of response were studied in 48 human immunodeficiency virus-infected children. Disappearance of ddI from plasma after the intravenous dose was rapid and biexponential, with half-lives of 12 min and 1.0 h and a total clearance of 510 +/- 180 ml/min/m2. After oral administration, ddI absorption was limited and variable (mean bioavailability, 19% +/- 17%). A plasma ddI concentration-response relationship was observed for both decline in viral p24 antigen levels and improvement in intelligence quotient score. A limited sampling model was developed that accurately predicts the area under the ddI plasma concentration-time curve from one to three plasma samples. Although this pharmacokinetic study was done in children, the results also have relevance to adults and suggest that individualization of dose and schedule through therapeutic drug monitoring may be necessary to achieve optimal response.

Absorption↗
PubMed1986

Nitrogen fixation in molybdenum-deficient continuous culture by a strain of Azotobacter vinelandii carrying a deletion of the structural genes for nitrogenase (nifHDK).

Steady-state chemostat cultures of Azotobacter vinelandii strain CA11, carrying a deletion of genes encoding the structural polypeptides of nitrogenase nifHDK, were established in a simple defined medium chemically purified to minimize contamination by Mo. The medium contained no utilizable N source. Growth was dependent on N2 (1.1 X 10(8) viable cells X ml-1 at D = 0.176 h-1), and was inhibited by Mo (20 nM). DNA hybridization showed the deletion to be stable during prolonged (55 days) growth in the chemostat (132 doublings). Since batch cultures, using unsupplemented 'spent' chemostat medium, showed good growth (1.9 X 10(8) cells X ml-1), no requirement for subnanomolar concentrations of Mo was found. The biomass yield, as the dilution rate (D) was varied, showed that the N content of the culture, protein and dry wt. increased as D was decreased, indicating that neither N2 nor O2 were limiting growth. The limiting nutrient was not identified. Substantial amounts of H2 were evolved by the chemostat cultures, probably as the result of inhibition of O2-dependent hydrogenase activity by nitrilotriacetic acid present in the medium. Over a range of D values approx. 50% of the electron flux through the alternative system was allocated to H+ reduction. C2H2 was a poor substrate, being reduced at 0.14-0.1 times the rate of N2 fixation, calculated from the N content of the cells. SO4(2-)-limited steady-state continuous cultures of strain UW136 (wild-type for nifHDK) had a 2-fold greater biomass in the presence of MoO4(2-) (1 microM). The significance of this finding for 'Mo-limited' continuous cultures [Eady & Robson (1984) Biochem. J. 224, 853-862] is discussed.

Azotobacter↗
PubMedDate not supplied

Quality videotapes with the help of a computer.

The last few years have seen a tremendous growth in videocassette usage, not only for entertainment, but also as a viable teaching method. Most homes in American now have at least one VCR. At Ozarka Vo Tech in Melbourne, AR, educators recognize the educational value of videotapes and have combined efforts to produce several quality computer-generated videotapes. With funding from projects, P189-01 A Competency-Based, Computer-Assisted, And Computer-Managed Model LPN Program, and the PI 2B061 Comprehensive Learning Lab, educators have been able to produce teacher-made videotapes to augment the different educational programs at our school. This article describes the method used, equipment needed, and general hints for improving the quality of teacher-made videotapes.

Humans↗