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Biomedical subjects

K Davis

Publications and source records attributed to K Davis.

At least 181 records · Page 10Linked to original sources
PubMed1995

Relative genotoxic activities of pesticides evaluated by a modified SOS microplate assay.

The genotoxic activities of 47 pesticides were determined using a modified SOS microplate assay in which the induction of beta-galactosidase in E. coli PQ37 was used as a quantitative measure of genotoxic activity. The results were compared with those obtained with anethole, curcumin, and capsaicin, a few examples of naturally occurring compounds present in foods. The assays were conducted with pesticides dissolved either in a suitable solvent, such as 10% DMSO in physiological saline or dispersed in sodium taurocholate micelles, to simulate conditions in the small intestine from where these substances are normally absorbed from the diet. 4-Nitroquinoline oxide (4-NQO) served as the reference standard of a direct acting mutagen. In micellar form, 4-NQO and 25 of the 47 pesticides tested showed significantly higher genotoxic activities than when they were tested in an organic solvent. In micellar form the SOS inducing potency of 4-NQO was almost twice as high as in 10% DMSO in physiological saline. In taurocholate micelles, the five most active compounds had activities in the range of 1,234-3,765 units/mumol and in the order of decreasing activities they were ranked as follows: malathion > dichlorvos > lindane > chlordane > endrin. They were significantly less active than 4-NQO (less than 40%). In micellar solution the naturally occurring compounds, anethole, curcumin, and capsaicin gave activities of 4,594, 928, and 809 units/mumol, respectively. These studies show that genotoxicity may depend upon the environment in which cells are exposed to these potential genotoxins. It appears that testing of the more hydrophobic compounds, both synthetic and naturally occurring, are needed.

DNA Damage↗
PubMed1995

Surveillance venous scans for deep venous thrombosis in multiple trauma patients.

The high reported incidence of deep venous thrombosis (DVT) in trauma patients has prompted surveillance venous duplex scanning of the lower extremities. We report our retrospective experience with 183 multiple trauma patients who were admitted to the surgical intensive care unit and underwent 261 surveillance venous scans. There were 122 men and 61 women whose average age was 38 years. All patients were treated prophylactically with either extremity pneumatic compression or subcutaneous heparin to prevent DVT. Most (87%) patients suffered blunt trauma and had either head (3%), spinal (3%), intra-abdominal (9%), or lower extremity (17%) injuries or a combination of injuries (68%). Almost two thirds of the patients had no symptoms suggestive of possible DVT. Of the 261 venous scans performed, 239 (92%) were normal, 16 (6%) were positive for proximal lower extremity DVT, and six (2%) showed thrombus limited to the calf veins. Patients with symptoms of lower extremity DVT were significantly more likely to have proximal DVT compared to those without symptoms (15% vs. 5%, p < 0.05). Patients with spinal injuries also had a higher incidence of proximal DVT (18% vs. 6%, p < 0.05). At current hospital charges, the cost to identify each proximal DVT was $6688. If surveillance duplex scans were performed on all trauma patients in the surgical intensive care unit, the national annual expense would be $300,000,000. Routine DVT surveillance is expensive and should be reserved for symptomatic patients or those with spinal injuries.

Adult↗
PubMed1995

Circulating Fc gamma receptor-specific autoantibodies in localized and systemic scleroderma.

BACKGROUND: Anti-Fc gamma receptor (anti-Fc gamma R) autoantibodies occur in patients with systemic scleroderma. Their clinical significance is unknown. OBJECTIVE: Our purpose was to determine the incidence of anti-Fc gamma R autoantibodies in patients with localized and systemic scleroderma and to examine the relation between these autoantibodies, the severity of the disease, and the presence of other autoantibodies. METHODS: Patients were placed into three clinical groups: three had diffuse systemic scleroderma, 47 had limited systemic scleroderma, and nine had localized systemic scleroderma. Antinuclear antibody titer and pattern were measured by indirect immunofluorescence with human epithelial (HEp)-2 cells and tissue sections, whereas anti-Scl-70 antibodies were measured by gel diffusion technique. Anti-Fc gamma R autoantibodies were measured in serum from patients and from 25 healthy persons by enzyme-linked immunosorbent assay with human recombinant Fc gamma RII (CD32) and Fc gamma RIII (CD16). RESULTS: Anti-Fc gamma R autoantibodies were detected in 54% of patients and in none of the healthy control subjects. Autoantibodies were present in all three clinical groups and were most frequently directed against Fc gamma RIII. Correlation between patients' clinical and laboratory data and anti-Fc gamma R autoantibodies could not be demonstrated. CONCLUSION: The presence of anti-Fc gamma R autoantibodies in the serum of patients with either systemic or localized scleroderma and the lack of these autoantibodies in healthy persons suggest that they may play a role in the pathogenesis of these diseases.

Adolescent↗
PubMed1995

Phonetic and phonological contrasts in the acquisition of voicing: voice onset time production in Hindi and English.

The present study examines adult and child word-initial voice onset time productions in English and Hindi (10 adults and 20 children in each language) to determine the age of acquisition of the phonemic voice contrast. Cross-linguistic differences in patterns of acquisition were found, but these need not be traced to the different phonological systems per se. An examination of the data indicates that the best predictor of age of voice contrast acquisition across languages is one which rests on the actual acoustic differences between members of phonologically contrastive pairs. In general it was found that the larger the post-release voice onset time differences between pair members in the adult model, the earlier the contrast is reliably produced by child language learners.

Acoustic Stimulation↗
PubMed1995

White cell reduction in platelet concentrates and packed red cells by filtration: a multicenter clinical trial. The Trap Study Group.

BACKGROUND: Most previous studies on white cell (WBC) reduction by filtration have been small-scale studies conducted under tightly controlled laboratory conditions. Their results would be the ideal, rather than what might be expected during routine operation. STUDY DESIGN AND METHODS: To obtain information on routine filtration of blood components, data have been collected from a large-scale, ongoing, multicenter clinical trial designed to determine the effectiveness of WBC reduction in or ultraviolet B radiation of platelet concentrates before transfusion in preventing platelet alloimmunization and platelet transfusion refractoriness. The WBC content of blood components both before and after filtration was determined by automated cell counters and a manual propidium iodide-staining method, respectively. Platelet and red cell losses during filtration were measured. RESULTS: The average platelet losses after filtration were 24 +/- 15 percent and 20 +/- 9 percent for apheresis platelets and pooled platelets, respectively. The frequencies at which filtered platelet concentrates contained high levels of residual WBCs (> 5 x 10(6)) were 7 percent and 5 percent for apheresis platelets and pooled platelets, respectively. Further analysis of the platelet filtration data showed that greater numbers of total initial WBCs in the pooled platelets were associated with increased percentages of filtration failure (> 5 x 10(6) residual WBCs). For packed red cells, the average losses during filtration were 23 +/- 4 percent and 15 +/- 3 percent for CPDA-1 units and Adsol units, respectively. The frequencies at which filtered red cells contained > 5 x 10(6) residual WBCs were 2.7 percent for one type of filter and 0.3 percent for another type of filter. CONCLUSION: There were significant losses of platelets during filtration, which could add to the costs of WBC reduction and lead to possible increases in donor exposures. Filtration failures still occurred, despite careful observation of the standard filtration procedures. The number of total WBCs in pooled platelets before filtration has been identified as an important factor in determining the success of WBC reduction.

Blood Platelets↗
PubMed1995

Relationship between virulence and immunity as revealed in recent studies of the F1 capsule of Yersinia pestis.

Yersinia pestis, the causative agent of plague, possesses multiple virulence determinants encoded on its three plasmids and on its chromosome. We evaluated the role of the protein capsule F1 in virulence an immunity against plague. Strains lacking F1, either those that are naturally occurring or those with genetically defined nonpolar mutations in the structural gene, retained their virulence for mice and nonhuman primates. However, both active immunization with F1, from either a recombinant vector or Y. pestis, and passive immunization with F1 monoclonal antibody protected mice from experimental infection with wild-type F1-positive organisms. These results suggest that protective immunogens like F1 need not be essential for virulence. The rare isolation of virulent F1-negative organisms from F1-immunized animals infected with F1-positive strains supports this conclusion and also suggests that, in addition to F1, an optimal vaccine against plague should include essential virulence factors as immunogens.

Animals↗
PubMed1995

Quality assurance for contracting of education: a delegated system involving consortia of British National Health Service trusts.

With the creation of the market for education, some regional health authorities (RHAs) in England are inclined to formally involve National Health Service (NHS) trusts in decisions with regard to the nature and location of education contracts. This paper describes a delegated system developed for the South East Thames Regional Health Authority and now being introduced within the Eastern Sector of the South Thames Regional Health Authority. Key features of the system include delegated contract review and a quality levels analysis in which the interests of the RHA and trusts (in both individual and consortium configurations) are accommodated.

Contract Services↗
PubMed1995

Lung compliance following cardiac arrest.

OBJECTIVE: To determine lung compliance in patients who had out-of-hospital cardiac arrests. METHODS: A prospective, observational study of patients suffering nontraumatic cardiopulmonary arrest and requiring CPR at one university hospital ED. Following termination of resuscitation efforts, lung compliance was measured. Measurements were made while inflating the lung from 250 mL to 2,000 mL (in 250-mL increments) using a calibrated supersyringe. Airway flow and pressure were measured at the endotracheal tube with a pneumotachograph and a pressure transducer. Flow and pressure signals were recorded by a respiratory monitor and used to construct pressure-volume curves for calculation of lung compliance. RESULTS: The 25 cardiac arrest patients (17 men, eight women) had a mean (+/- SD) age of 65 +/- 7 years. Mean lung compliance was 0.051 +/- 0.011 L/cm H2O. Lung compliance was smaller at low lung volumes, suggesting the presence of alveolar collapse. Compliance values from 500 mL to 1,500 mL were similar. Compliance also diminished with increasing duration of CPR. CONCLUSIONS: One previous publication suggested that lung compliance following resuscitation is 0.022 L/cm H2O. The results of this study, using the accepted standard measurements of static lung compliance, suggest that true compliance is twice this value. This finding has important ramifications for future research on ventilation during resuscitation and current ventilation standards.

Adult↗
PubMed1995

Out-of-hospital ventilation: bag--valve device vs transport ventilator.

OBJECTIVE: To examine the patterns of out-of-hospital airway management and to compare the efficacy of bag-valve ventilation with that of the use of a transport ventilator for intubated patients. METHODS: A prospective, nonrandomized, convenience sample of 160 patients requiring airway management in the out-of-hospital urban setting was analyzed. A survey inquiring about airway and ventilatory management was completed by emergency medical services (EMS) personnel, and arterial blood gas (ABG) samples were obtained within 5 minutes of patient arrival in the ED. The ABG parameters were compared for patients grouped by different airway techniques and presence or absence of cardiac arrest (systolic blood pressure < 50 mm Hg) upon ED presentation. RESULTS: Over a one-year period, 160 surveys were returned. The majority (62%) of the patients were men; the population mean age was 61 +/- 19 years. Presenting ABGs were obtained for 76 patients; 17% (13/76) had systemic perfusion and 83% (63/76) were in cardiac arrest. There was no difference in ABG parameters between the intubated cardiac arrest patients ventilated with a transport ventilator (pH 7.17 +/- 0.17, PaCO2 37 +/- 20 torr, and PaO2 257 +/- 142 torr) and those ventilated with a bag-valve device (pH 7.20 +/- 0.16, PaCO2 42 +/- 21 torr, and PaO2 217 +/- 138 torr). The patients ventilated via an esophageal obturator airway (EOA) device had impaired gas exchange, compared with the groups who had endotracheal (ET) intubation (pH 7.09 +/- 0.13, PaCO2 76 +/- 30 torr, and PaO2 75 +/- 35 torr). The intubated patients not in cardiac arrest had similar ABG parameters whether ventilated manually with a bag-valve device or with a transport ventilator. Endotracheal intubation was successfully accomplished in 93% (123/132) of attempted cases. CONCLUSIONS: In this sample, ET intubation was the most frequently used airway by EMS providers. When ET intubation was accomplished, adequate ventilation could be achieved using either bag-valve ventilation or a transport ventilator. Ventilation via the EOA proved inadequate.

Adult↗
PubMed1995

Choice matters: enrollees' views of their health plans.

Enrollees' views of their health plans and physicians are important measures of the performance of the health care system. The Commonwealth Fund's 1994 survey of 3,000 adults in fee-for-service and managed care organizations documents enrollees' experiences with choosing a plan and satisfaction with that plan. Fee-for-service enrollees were more satisfied with their plan's access to and quality of care; managed care enrollees were more satisfied with their plan's cost, paperwork, and coverage of preventive care. The survey also found a high rate of involuntary plan changing, limited choice of physicians, and low levels of satisfaction among low-income managed care enrollees.

Adolescent↗
PubMed1995

Preserving and strengthening Medicare.

Any restructuring or reform of Medicare should first and foremost preserve the integrity of the program. Contrary to current rhetoric, Medicare offers mainstream medical care for the most difficult-to-insure Americans, and over the past ten years its record of holding down costs has been better than that of the private insurance sector. For the very long term, when demographic changes place even greater pressures on Medicare, all dimensions of the program need to be considered in the search for a long-range solution, including asking beneficiaries and/or taxpayers to contribute more to the program. Expansion of managed care choices should certainly be part of any restructuring, but careful attention to improving the basic fee-for-service Medicare program--which will continue to serve a majority of beneficiaries for many years to come--also is needed.

Cost Control↗
PubMed1995

Prescribing for older patients: how to avoid toxic drug reactions.

As a group, persons age 65 and older are the largest consumers of pharmaceuticals, accounting for 30% of prescription drugs and 40% of over-the-counter medications. Many elderly patients take multiple medications for a variety of concurrent medical conditions. The use of two or more drugs, combined with widely varying degrees of disease-related and physiologic impairment of function, can lead to unintended adverse reactions and even death. The physician can help to minimize adverse drug reactions and improve outcomes by being aware of the principles of clinical pharmacology, the characteristics of specific drugs, and the special physical, psychological, and social needs of older patients.

Aged↗
PubMed1995

Health insurance: the size and shape of the problem.

Assessment of experiences with health care will continue to be important given the rapid changes in the health care system and retreat from broad national attention on health reform. This paper reports on the findings of the 1993 Kaiser/Commonwealth Survey of Americans and their health insurance. The survey findings highlight the chronic problem of uninsurance as well as concerns among those with insurance, including the worry that benefits will be reduced or become unaffordable. Limited choice of health plans and providers and having to join a managed care plan are further concerns. These findings suggest that many Americans' needs remain unaddressed, but they will have to be considered as the health care system is restructured.

Consumer Behavior↗