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Biomedical subjects

E Tu

Publications and source records attributed to E Tu.

5 recordsLinked to original sources
PubMed1997

Electric field directed nucleic acid hybridization on microchips.

Selection and adjustment of proper physical parameters enables rapid DNA transport, site selective concentration, and accelerated hybridization reactions to be carried out on active microelectronic arrays. These physical parameters include DC current, voltage, solution conductivity and buffer species. Generally, at any given current and voltage level, the transport or mobility of DNA is inversely proportional to electrolyte or buffer conductivity. However, only a subset of buffer species produce both rapid transport, site specific concentration and accelerated hybridization. These buffers include zwitterionic and low conductivity species such as: d- and l-histidine; 1- and 3-methylhistidines; carnosine; imidazole; pyridine; and collidine. In contrast, buffers such as glycine, beta-alanine and gamma-amino-butyric acid (GABA) produce rapid transport and site selective concentration but do not facilitate hybridization. Our results suggest that the ability of these buffers (histidine, etc.) to facilitate hybridization appears linked to their ability to provide electric field concentration of DNA; to buffer acidic conditions present at the anode; and in this process acquire a net positive charge which then shields or diminishes repulsion between the DNA strands, thus promoting hybridization.

Buffers↗
PubMed1997

Rapid determination of single base mismatch mutations in DNA hybrids by direct electric field control.

We have demonstrated that controlled electric fields can be used to regulate transport, concentration, hybridization, and denaturation of single- and double-stranded oligonucleotides. Discrimination among oligonucleotide hybrids with widely varying binding strengths may be attained by simple adjustment of the electric field strength. When this approach is used, electric field denaturation control allows single base pair mismatch discrimination to be carried out rapidly (<15 sec) and with high resolution. Electric field denaturation takes place at temperatures well below the melting point of the hybrids, and it may constitute a novel mechanism of DNA denaturation.

Bacterial Proteins↗
PubMed1996

Probabilities and lifetime durations of short-stay hospital and nursing home use in the United States, 1985.

OBJECTIVES: The authors present a four-state increment-decrement life table model from which estimates of the risk and duration of nursing home and short-term hospital stays in the United States are derived. METHODS: Survival analysis was used to generate various transition probabilities while controlling for population heterogeneity. In addition, a newly developed algorithm was applied to construct the multistate life table specifically for health-care use. RESULTS: The results reveal that in 1985, a US civilian is expected to spend 72.35 years in the community, 59.5 days in short-stay hospitals, and 2.28 years in nursing homes throughout his or her lifetime. CONCLUSIONS: The single-year risk of nursing home and short-stay hospital use is shown to be an increasing function of age, especially for the older adults.

Adolescent↗
PubMed1994

Canine, human, and rat plasma insulin responses to galanin administration: species response differences.

Previous studies demonstrated that porcine galanin is a potent inhibitor of insulin secretion in many species but fails to alter human insulin secretion. To resolve whether this discrepancy was due to the use of a heterologous peptide or to a true species response difference, we studied the effect of a synthetic replicate of human galanin on glucose-stimulated insulin secretion in rats, dogs, and humans. On administration into rats, human and rat galanin significantly inhibited glucose-induced insulin responses to a similar degree. Similarly, porcine and human galanin significantly elevated canine plasma glucose and inhibited canine plasma insulin responses. In contrast, plasma glucose and insulin responses to glucose administration in humans were unaltered by the addition of human galanin at or above the maximum effective dose employed in dogs. Possible effects of galanin administration were seen on human glucagon and pancreatic polypeptide responses to glucose at the highest dose of human galanin infused. We conclude that galanin probably does not play a major role in modulating human beta-cell function.

Adult↗