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Biomedical subjects

K Davis

Publications and source records attributed to K Davis.

At least 127 records · Page 7Linked to original sources
PubMed1998

Effects of inhaled nitric oxide in patients with acute respiratory distress syndrome: results of a randomized phase II trial. Inhaled Nitric Oxide in ARDS Study Group.

OBJECTIVES: To evaluate the safety and physiologic response of inhaled nitric oxide (NO) in patients with acute respiratory distress syndrome (ARDS). In addition, the effect of various doses of inhaled NO on clinical outcome parameters was assessed. DESIGN: Prospective, multicenter, randomized, double-blind, placebo-controlled study. SETTING: Intensive care units of 30 academic, teaching, and community hospitals in the United States. PATIENTS: Patients with ARDS, as defined by the American-European Consensus Conference, were enrolled into the study if the onset of disease was within 72 hrs of randomization. INTERVENTIONS: Patients were randomized to receive placebo (nitrogen gas) or inhaled NO at concentrations of 1.25, 5, 20, 40, or 80 ppm. MEASUREMENTS AND MAIN RESULTS: Acute increases in PaO2, decreases in mean pulmonary arterial pressure, intensity of mechanical ventilation, and oxygenation index were examined. Clinical outcomes examined were the dose effects of inhaled NO on mortality, the number of days alive and off mechanical ventilation, and the number of days alive after meeting oxygenation criteria for extubation. A total of 177 patients were enrolled over a 14-month period. An acute response to treatment gas, defined as a PaO2 increase > or =20%, was seen in 60% of the patients receiving inhaled NO with no significant differences between dose groups. Twenty-four percent of placebo patients also had an acute response to treatment gas during the first 4 hrs. The initial increase in oxygenation translated into a reduction in the FIO2 over the first day and in the intensity of mechanical ventilation over the first 4 days of treatment, as measured by the oxygenation index. There were no differences among the pooled inhaled NO groups and placebo with respect to mortality rate, the number of days alive and off mechanical ventilation, or the number of days alive after meeting oxygenation criteria for extubation. However, patients receiving 5 ppm inhaled NO showed an improvement in these parameters. In this dose group, the percentage of patients alive and off mechanical ventilation at day 28 (a post hoc analysis) was higher (62% vs. 44%) than the placebo group. There was no apparent difference in the number or type of adverse events reported among those patients receiving inhaled NO compared with placebo. Four patients had methemoglobin concentrations >5%. The mean inspired nitrogen dioxide concentration in inhaled NO patients was 1.5 ppm. CONCLUSIONS: From this placebo-controlled study, inhaled NO appears to be well tolerated in the population of ARDS patients studied. With mechanical ventilation held constant, inhaled NO is associated with a significant improvement in oxygenation compared with placebo over the first 4 hrs of treatment. An improvement in oxygenation index was observed over the first 4 days. Larger phase III studies are needed to ascertain if these acute physiologic improvements can lead to altered clinical outcome.

Acute Disease↗
PubMed1998

An emancipatory impulse: a feminist postmodern integrated turning point in nursing research.

This article critiques the current debates regarding feminism, postmodernism, and feminist/postmodernism within nursing research. The critique classified the debates into three identifiable constructs: dissatisfaction, fragmentation, and integration. The authors propose a solution from the integration debate as an emancipatory "workable" turning point for nursing research. The solution is situated within feminism and draws on the epistemological constructs of both modernism and postmodernism. Nursing research is framed within the proposed ontological links that characterize the integrated solution.

Female↗
PubMed1998

Anaesthesia circuits, humidity output, and mucociliary structure and function.

We compared the effects of humidity delivered by the circle system at low fresh gas flows (FGF) with a conventional two-limb and coaxial circuit on the structure and function of the tracheobronchial epithelium in dogs. Animals were anaesthetized and mechanically ventilated using an anaesthesia ventilator to maintain normocarbia. Group I (control) animals received a FGF equal to the required minute ventilation mimicking an open circuit technique. Group II and III animals had FGF set at 20% of the required minute ventilation. Group II used a two-limb circuit and Group III used a coaxial circuit. Relative humidity and temperature of inspired gases were measured at baseline and hourly afterwards. In the first experiment, biopsies of the tracheobronchial tree were obtained bronchoscopically at baseline and then hourly for six hours. Microscopic examination of these samples allowed calculation of mean ciliary length. In the second experiment, tracheal mucus flow velocity (TMFV) was measured at baseline and hourly afterward, using a cinebroncho-fibrescopic method. Delivered absolute humidity was greatest with low FGF and the coaxial circuit, followed by low FGF and a conventional circuit, and high FGF (15 +/- 1.4 vs 9 +/- 0.8 vs 5 +/- 0.4 mg H2O, P < 0.01) after two hours. Mean cilia length (micron) and TMFV (mm/min) fell during the first hour in all three groups. At hour two TMFV returned to baseline in Group III and was significantly greater than Groups I and II (0.8 +/- 0.4 vs 8.6 +/- 1.1 vs 15.4 +/- 2.1, P < 0.001). Mean ciliary length demonstrated a similar pattern with reductions from baseline in all three groups for the first two hours. Groups II and III had an increase in cilia length beginning at hour three and were both significantly greater than Group I at hours 3 through 6 (1.3 +/- 0.5 vs 3.2 +/- 1.1 vs 4.2 +/- 0.8, P < 0.001). Alterations in tracheobronchial structure and function result from exposure to dry gases and are amplified by the duration of exposure. Our findings suggest a minimum of 12 to 15 mg H2O/l is necessary to prevent these alterations. In this study, the combination of low FGF and a coaxial anaesthesia circuit reached this minimum threshold more quickly than a conventional two-limb circuit.

Anesthesia, Closed-Circuit↗
PubMed1998

An in-house coordinator program to increase organ donation in public teaching hospitals.

The organ donor referral rates at Ben Taub General Hospital, a level 1 county trauma facility in Houston, Tex, were in the high 90s from 1993 through 1996. However, organs were procured from only 25% of those potential donors who were medically suitable. LifeGift Organ Donation Center identified two issues concerning the hospital's organ donor referrals: early medical management problems and a low consent rate. The hospital and LifeGift developed an in-house coordinator program along with specific protocols that have markedly increased the quantity of organ donors. In fiscal year 1994, 15 organ donors were recovered; in fiscal year 1995, following the implementation of the program, 25 organ donors were recovered. In fiscal year 1996, 39 organ donors were recovered. The in-house coordinators' consent rate was 72% of medically suitable potential donors. Early referrals for evaluation contributed to these successes.

Clinical Protocols↗
PubMed1998

An in-house coordinator program to increase organ donation in public trauma hospitals.

A 4-year retrospective study was conducted regarding the donor potential, consent rates, and organ recovery at a large 500-bed public trauma hospital. An independent organ procurement organization hired two in-house coordinators, one white and one black, to work exclusively in the hospital. The duties of the in-house coordinators included the following: working with nurses, physicians, and residents to identify donors; closely managing and coordinating the consent process; and assisting organ procurement coordinators in donor management. Following the program's implementation and the use of race-specific requesters, a 64% increase in consent rate resulted along with an overall increase of 94% in the number of organ donors. The consent rate of blacks increase 115%, whereas the number of black organ donors increased 154%. The Hispanic consent rate increased 48% with a corresponding increase of 83% in the number of Hispanic organ donors. In addition, the white consent rate increased from 55% (the 3-year average from 1993 to 1995) to 75% in 1996, resulting in a 36% increase following the implementation of the program. The investment of dedicated race-sensitive personnel in large urban county trauma facilities can result in a significant increase in donor conversion rates.

Hospitals, Public↗
PubMed1998

Listening to parents. A national survey of parents with young children.

OBJECTIVE: To document the child-rearing needs and pediatric health care experiences of parents with children from birth to 3 years old. DESIGN: A nationally representatives sample of 2017 parents with children younger than 3 years using a 25-minute structured telephone questionnaire. Interviews were completed by 68% of the screened eligible respondents. The margin of sampling error for results at the 95% confidence level was +/- 3 percentage points. RESULTS: Seventy-six percent of children younger than 3 years were reported by parents to be in excellent health; 88% had a regular source of pediatric health care. Seventy-one percent of parents who received special pediatric services rated their child's physician as excellent in providing good health care. Seventy-nine percent of parents reported they could use more information in at least 1 of 6 areas of child rearing, and 53% wanted information in at least 3 areas. Forty-two percent had talked with their child's physician about "nonmedical" concerns; 39% of parents read to or looked at a picture book with their child on a daily basis; 51% of parents set daily routines for meals, naps, and bedtime. Breast-feeding and reading to the child on a daily basis were much more likely if a physician encouraged parents to do so. CONCLUSIONS: Most parents view the pediatric health care system as meeting the physical health needs of their young children. Parents want more information and support on child-rearing concerns, yet pediatric clinicians often fail to discuss nonmedical questions with them. The interventions of pediatric clinicians can positively affect parental behavior. Pediatric practices should consider creative ways to reconstitute and augment their current services and systems of care.

Adult↗
PubMed1997

Carbamoylation of brain glutamate receptors by a disulfiram metabolite.

S-Methyl-N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO), a metabolite of the drug disulfiram, is a selective carbamoylating agent for sulfhydryl groups. Treatment of glutamate receptors isolated from mouse brain with DETC-MeSO blocks glutamate binding. In vivo, carbamoylated glutathione, administered directly to mice or formed by reaction of DETC-MeSO with glutathione in the blood, also blocks brain glutamate receptors. Carbamoyl groups appear to be delivered to brain glutamate receptors or to liver aldehyde dehydrogenase in vivo by a novel glutathione-mediated mechanism. Seizures caused by the glutamate analogs N-methyl-D-aspartate and methionine sulfoximine, or by hyperbaric oxygen, are prevented by DETC-MeSO, indicating that carbamoylation of glutamate receptors gives an antagonist effect. These observations offer an explanation for some of the previously reported neurological effects of disulfiram, such as its ability to prevent O2-induced seizures. Furthermore, some of the physiology of the disulfiram-ethanol reaction, that could not be accounted for based on the known inhibition of aldehyde dehydrogenase alone, may be explained by disulfiram's effect on glutamate receptors.

Animals↗
PubMed1997

The effects of different stressors on extracellular 5-hydroxytryptamine and 5-hydroxyindoleacetic acid.

The effects of application of five different stressors on extracellular 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the striatum and hippocampus were compared using in vivo microdialysis. Forced swimming for 30 min elevated extracellular 5-hydroxytryptamine to 90% above basal levels and reduced 5-hydroxyindoleacetic acid to 45% of basal levels in the striatum during the swim session. In contrast, hippocampal 5-hydroxytryptamine was not altered significantly by forced swimming but 5-hydroxyindoleacetic acid levels were reduced to 60% of basal levels. Tail pinch for 5 min elevated 5-hydroxytryptamine to 55% above basal levels in striatum and to 35% above basal levels in hippocampus. Tail pinch had no effect on 5-hydroxyindoleacetic acid in either brain region. In contrast to forced swimming and the tail pinch, the other three stressors, immobilization stress for 100 min, exposure to a cold environment (4 degrees C) for 2 h, and forced motor activity on a rotarod for 30 min, failed to alter extracellular 5-hydroxytryptamine in either the striatum or the hippocampus. All five stressors increased plasma corticosterone levels: tail pinch, 246%; cold stress, 432%; immobilization, 870%; forced motor activity, 1030%; and forced swimming, 1530%. These results suggest that individual stressors produce different effects on extracellular 5-hydroxytryptamine in different brain regions. In addition, there does not appear to be a relationship between the effects of stressors on the 5-hydroxytryptamine system and the magnitude of their ability to activate the hypothalamic-pituitary-adrenal axis.

Animals↗
PubMed1997

The nucleotide sequence of Saccharomyces cerevisiae chromosome XVI.

The nucleotide sequence of the 948,061 base pairs of chromosome XVI has been determined, completing the sequence of the yeast genome. Chromosome XVI was the last yeast chromosome identified, and some of the genes mapped early to it, such as GAL4, PEP4 and RAD1 (ref. 2) have played important roles in the development of yeast biology. The architecture of this final chromosome seems to be typical of the large yeast chromosomes, and shows large duplications with other yeast chromosomes. Chromosome XVI contains 487 potential protein-encoding genes, 17 tRNA genes and two small nuclear RNA genes; 27% of the genes have significant similarities to human gene products, and 48% are new and of unknown biological function. Systematic efforts to explore gene function have begun.

Base Sequence↗
PubMed1997

Abc1: a new ABC transporter from the fission yeast Schizosaccharomyces pombe.

We have isolated the abc1 gene from the fission yeast Schizosaccharomyces pombe. Sequence analysis suggests that the Abc1 protein is a member of the ABC superfamily of transporters and is composed of two structurally homologous halves, each consisting of a hydrophobic region of six transmembrane domains and a hydrophilic region containing one ATP-binding site. The abc1 gene appears to be expressed under all growth conditions but gene disruption experiments indicate that it is not essential for growth. The sequence of the abc1 gene has been deposited in the EMBL data library under the Accession Number Y09354.

ATP-Binding Cassette Transporters↗
PubMed1997

Deep brain stimulation and thalamotomy for tremor compared.

Deep brain stimulation (DBS) and thalamotomy are both capable of abolishing tremor. However, no technique is perfect and if thalamotomy proves inadequate so that tremor recurs, presumably because of suboptimal lesion location, the only option is to repeat the thalamotomy. With DBS all that has been necessary to date is to change the parameters of stimulation. Similarly with complications such as the "cerebellar" ones and paraesthesiae. If these occur after thalamotomy one can only wait and hope that they will subside and they do not always do so. With DBS, changing the parameters in the authors' patients has so far been successful in eliminating them. DBS, like thalamotomy is very effective for controlling tremor in Parkinson's disease (PD) and essential tremor (ET) and for improving dexterity in ET, but both techniques are less useful for the control of dopa dyskinesia, Parkinsonian rigidity, or impaired dexterity in PD, though DBS may be better than thalamotomy for the latter condition. On the other hand, both DBS and thalamotomy are very effective in improving dexterity in PD and ET may depend upon the fact that in PD bradykinesia is a major component, whereas in ET only the tremor is. The advantages of DBS over thalamotomy have to be weighed against the peculiar risks of DBS and of course, its cost.

Adult↗
PubMed1997

Use of the rapid/shallow breathing index as an indicator of patient work of breathing during pressure support ventilation.

BACKGROUND: Measuring patient work of breathing (WOBpt) has been suggested to provide safe, aggressive weaning from mechanical ventilation. We compared WOBpt and pressure-time-product (PTP) to routine weaning parameters [breath rate (f), tidal volume (VT), frequency/tidal volume ratio (f/VT)] at different levels of pressure support ventilation (PSV). METHODS: Fifteen patients in the surgical intensive care unit requiring prolonged weaning (more than 3 days) were entered in the study. A balloon-tipped esophageal catheter was placed and position confirmed by inspection of pressure and flow waveforms. Each patient was randomly assigned to breathe with 5, 10, 15, and 20 cm H2O of PSV. After 30 minutes, 40 breaths were recorded and analyzed. Measurement of WOBpt PTP, f, VT, and f/VT were made using the Bicore CP-100 monitor. Mean values for each parameter were calculated. PTP and WOBpt were plotted against f/VT to determine correlation coefficient. RESULTS: PTP, WOBpt and f/VT decreased in a stepwise fashion as PSV was increased. The f/VT correlated most closely with WOBpt (r = 0.983) and PTP (r = 0.972). Monitoring f alone also correlated with WOBpt (r = 0.894) and PTP (r = 0.881). All patients were weaned from the ventilator (mean duration, 22 +/- 5.9 days). Nine patients required tracheostomy before final liberation from the ventilator (mean duration, 22 +/- 5.9 days). Nine patients required tracheostomy before final liberation from the ventilator. CONCLUSIONS: Direct measurement of WOBpt is invasive, expensive, and' may be confusing to clinicians. Monitoring f/VT may be useful when changing PSV during weaning.

Acute Disease↗
PubMed1997

The effect of early versus late fasciotomy in the management of extremity trauma.

BACKGROUND: Recent reports have demonstrated an increase in the number of complications associated with delayed timing of fasciotomy for trauma. This study examines the effectiveness of early (less than 12 hours) versus late (more than 12 hours) fasciotomy in the injured extremity. METHODS: This is a retrospective review of 88 patients undergoing fasciotomy for extremity trauma admitted to the University of Cincinnati from January 1990 through December 1995. Records were reviewed for demographics, compartment pressures, time and type of fasciotomy, complications, limb salvage, and mortality. Statistical analysis was determined with chi-squared, multivariant regression analysis, and Student's t test with significance at p less than 0.05. RESULTS: Sixty-one (69%) patients had fasciotomy performed before 12 hours and twenty-seven (31%) after 12 hours. Although the rates of infection differed significantly between the two groups (7.3% for early versus 28% for late), the rates of limb salvage and neurologic sequelae were similar. Age, mechanism, shock, associated injuries, and time to fasciotomy were not predictive of complications. CONCLUSIONS: Fasciotomy for trauma is most efficacious when performed early. However, when performed late, it results in similar rates of limb salvage as compared with early fasciotomy but at the increased risk of infection. These results support aggressive use of fasciotomy in extremity trauma regardless of time of diagnosis.

Adult↗