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Biomedical subjects

Gregory Peterson

Publications and source records attributed to Gregory Peterson.

4 recordsLinked to original sources

Preference and resource utilization in elderly patients: InnoLet versus vial/syringe.

InnoLet is a disposable insulin injection device with a large easy-to-read dial, large push button for injection, and audible clicks for each unit injected. This clinical trial assessed patient preference, satisfaction, and utilization of healthcare resources (estimated nursing care) for InnoLet and vial/syringe. Patients with diabetes mellitus (N=79, mean age 68.2+/-8.6 years, duration of diabetes 16.5+/-10.9 years) having visual and/or motor disabilities and having difficulty (or required caregiver assistance) for previous injections by vial/syringe were randomized to use of either InnoLet or vial/syringe for 6 weeks, then switched to the alternate regimen for 6 weeks. At the end of the study, utilization of healthcare resources was assessed in terms of the caregiver time required to assist in preparation, storage, and disposal of each device. For vial/syringe, 60% of patients required assistance in drawing up the appropriate dosage in the syringe, and 36% of patients required assistance when injecting insulin. A major portion of the patients (53%) could independently conduct injections (without nursing/caregiver assistance) during use of InnoLet, versus 20% for vial/syringe. As a result, mean daily nursing costs associated with the injection regimen were US$ 114 for the InnoLet device, and US$ 196 for vial/syringe (P<0.001). A majority of patients (82%) indicated a preference for the InnoLet device (P<0.001).

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Tn5 transposase active site mutations suggest position of donor backbone DNA in synaptic complex.

Tn5 transposase (Tnp), a 53.3-kDa protein, enables the movement of transposon Tn5 by a conservative mechanism. Within the context of a protein and DNA synaptic complex, a single Tnp molecule catalyzes four sequential DNA breaking and joining reactions at the end of a single transposon. The three amino acids of the DDE motif (Asp-97, Asp-188, and Glu-326), which are conserved among transposases and retroviral integrases, have been shown previously to be absolutely required for all catalytic steps. To probe the effect of active site geometry on the ability to form synaptic complexes and perform catalysis, single mutations at each position of the DDE motif were constructed. The aspartates were changed to glutamates, and the glutamate was changed to an aspartate. These mutants were studied by performing in vitro binding assays using short oligonucleotide substrates simulating the natural substrates for the synaptic complex formation and subsequent transposition steps. The results indicate that the aspartate to glutamate mutations restrict synaptic complex formation with substrates resembling the natural transposon prior to transferred strand nicking. This suggests a structural model in which the donor backbone DNA, prior to nicking, occupies the same space that is invaded by the longer side chains present in the aspartate to glutamate mutants. Additionally, catalytic assays support the previous proposal that the active site coordinates two divalent metal ions.

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