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Biomedical subjects

R Spear

Publications and source records attributed to R Spear.

13 recordsLinked to original sources
PubMed1999

Regulated expression of green fluorescent protein under the control of Aureobasidium pullulans xylanase gene xynA.

A mutant form of the jellyfish cDNA encoding green fluorescent protein (GFP) was fused to the promoter of the Aureobasidium pullulans xylanase gene xynA and the expression vector pxynEGFP was introduced into A. pullulans. In a manner consistent with regulation of the native xynA gene, gfp activity was induced by xylose and repressed by glucose. The marker may be useful for monitoring populations of A. pullulans in situ and for identifying transcriptional control elements of xynA.

Animals↗
PubMed1999

Management of pediatric liver injuries: a 13-year experience at a pediatric trauma center.

PURPOSE: This study of traumatic liver injuries (LI) in children reviews the authors' management and identifies the indications for surgical intervention. METHODS: A total of 11,761 admissions over 13 years to a regional pediatric trauma center were surveyed. RESULTS: LI were identified in 328 children. Mechanisms included 39% pedestrians struck by a vehicle, 34% motor vehicle occupants, 13% falls or discrete blows to the abdomen, 5% bicycle injuries, 5% child abuse, and 4% penetrating injuries. Eighty-seven of patients with LI were treated nonoperatively with a mortality rate of 17%. Six percent of deaths were attributed to the LI and massive hemorrhage, all of which presented with cardiopulmonary resuscitation (CPR) in progress, with the remainder of deaths attributed to massive head, neck, or chest injuries (HNCI, 90%) and sepsis (4%). Surgery was performed in 13% of all LI and included major hepatic vascular injury (MHVI) repairs (34%), hepatorrhaphies (34%), lobectomies (27%), and biliary repairs (4%). Excluding the nonoperative group deaths, the need for blood transfusion of more than 25 mL/kg in the first 2 hours as an indicator of surgical necessity or a MHVI had, respectively, a sensitivity of 34% and 67%, specificity of 98% and 97%, positive predictive value of 79% and 53%, negative predictive value of 89% and 98%, and prediction accuracy of 88% and 95%. In the surgical management group, the mortality rate was 23% with 40% of deaths attributed to MHVI, 30% a combination of MHVI and HNCI, 20% massive HNCI, and 10% sepsis. CONCLUSIONS: The majority of pediatric LI are not associated with hemodynamic instability and can be successfully managed nonoperatively (72%). Hemodynamic instability, as defined by the need for blood transfusion in excess of 25 mL/kg within the first 2 hours, was a strong indicator of a MHVI, which was often a lethal injury (70%).

Adolescent↗
PubMed1999

Estimating maximum concentrations for open path monitoring along a fixed beam path.

Researchers have applied open path optical sensing techniques to a variety of workplace and environmental monitoring problems. Usually these data are reported in terms of a path-average (or path-integrated) concentration. When assessing potential human exposures along a beam path, this path-average value is not always informative, since concentrations along the path can vary substantially from the beam average. The focus of this research is to arrive at a method for estimating the upper-bound in contaminant concentrations over a fixed open beam path. The approach taken here uses a statistical model to estimate an upper-bound concentration based on a combination of the path-average and a measure of the spatial variability computed from point samples along the beam path. Results of computer simulations and experimental testing in a controlled ventilation chamber indicate that the model produced conservative estimates for the maximum concentration along the beam path. This approach may have many applications for open path monitoring in workplaces or wherever maximum concentrations are a concern.

Humans↗
PubMed1996

Development of an oligonucleotide probe for Aureobasidium pullulans based on the small-subunit rRNA gene.

Aureobasidium pullulans, a cosmopolitan yeast-like fungus, colonizes leaf surfaces and has potential as a biocontrol agent of pathogens. To assess the feasibility of rRNA as a target for A. pullulans-specific oligonucleotide probes, we compared the nucleotide sequences of the small-subunit rRNA (18S) genes of 12 geographically diverse A. pullulans strains. Extreme sequence conservation was observed. The consensus A. pullulans sequence was compared with other fungal sequences to identify potential probes. A 21-mer probe which hybridized to the 12 A. pullulans strains but not to 98 other fungi, including 82 isolates from the phylloplane, was identified. A 17-mer highly specific for Cladosporium herbarum was also identified. These probes have potential in monitoring and quantifying fungi in leaf surface and other microbial communities.

Base Sequence↗
PubMed1992

Appendiceal US scans: histologic correlation.

High-resolution in vitro ultrasonography (US) of 20 surgical appendiceal specimens was performed to compare appearances of appendiceal tissue at US with corresponding histologic features. With an articulated-arm system and micropositioner, precise spatial correlation was achieved. As elsewhere in the gastrointestinal tract, five distinct echo layers were observed. Normal and inflamed specimens demonstrated these layers, but the architecture became disorganized and indistinct in cases of appendicitis. Three measurements were made for each specimen: (a) overall cross-sectional diameter, including the lumen, (b) thickness of the submucosal echo layer, and (c) the combined thickness of both walls, excluding the lumen. For the inflamed specimens, a substantial increase in the thickness of the summed wall measurements was found. Wall US appearance alone may be misleading in differentiation of normal and abnormal appendices.

Adolescent↗
PubMed1991

A transportable, remote sensing, infrared air-monitoring system.

A transportable, remote sensing instrument has been built that is capable of performing real-time quantitative analysis of gas and vapor contaminants of workplace air. The emphasis in this system is on simplicity and sensitivity for use over pathlengths of up to 40 m. A method was developed to overcome the effect of nonanalyte species present in the background spectrum on the quantitation of analytes in the sample spectrum. In addition, results demonstrated that instrument response was proportional to the beam pathlength under homogeneous concentration conditions. The application of software capable of qualitative analysis was also demonstrated.

Air Pollutants, Occupational↗
PubMed1989

The effect of autocorrelation on the estimation of workers' daily exposures.

Daily 8-hr time-weighted average (TWA) measurements may not be independent since production rates, maintenance schedules, work practices, and ventilation can result in trends where consecutive values are correlated (autocorrelation). A sampling program which involves collection of measurements on consecutive days, therefore, can result in biased estimates of the mean and variance of the exposure distribution if a high degree of autocorrelation exists. Three simulated data sets were examined to assess the effects of autocorrelation on the estimation of exposure distributions. Results indicated that about 30% of estimated mean values from a highly-autocorrelated series were outside the 95% confidence interval observed for an uncorrelated series. Three data sets obtained from actual workplaces were found to have relatively little autocorrelation. This suggests that for workplaces such as those analyzed here, a random sampling program may not be necessary, and sequential sampling may produce accurate estimates of the parameters of the exposure distribution.

Air Pollutants, Occupational↗
PubMed1987

A note on the assessment of exposure using one-sided tolerance limits.

Conceptual problems with OSHA's use of an absolute standard have led to alternative methods of assessing exposures to toxic materials in the workplace. One of these methods employs a one-sided tolerance limit. This statistical approach is explored from three points of view--identifiability, sampling strategies and statistical power. In general, assessing risk in the work environment with tolerance limits is found to give inadequate answers in several important respects.

Humans↗
PubMed1982

Detection of experimental right ventricular necrosis using vectorcardiograms obtained during artificial pacing.

This study was carried out to evaluate the possible usefulness of the VCG obtained during right ventricular pacing in the diagnosis of right ventricular necrosis. Myocardial necrosis was produced by injecting 40% formalin into the ventricular walls of 18 open-chest mongrel dogs. The injections were made in the inferior wall of the left ventricle in nine dogs (Group A) and in the inferior wall of the right ventricle in the remaining nine dogs (Group B). Analysis of vectorcardiographic QRS loops obtained during artificial pacing of the right ventricular apex was made before and 60 minutes after the injections. In Group B, but not in Group A, the injections resulted in superior displacement of initial QRS forces as indicated by measurements of time, distance, amplitude and angle. The pacing VCG, performed in serial fashion, is a specific and sensitive means of detecting right ventricular inferior wall necrosis in the experimental animal. Application of these findings to the diagnosis of myocardial infarction in humans requires further investigation.

Animals↗
PubMed1981

Vectorcardiographic manifestations of experimental right ventricular necrosis.

This study was carried out to evaluate the possible usefulness of the VCG in the diagnosis of right ventricular necrosis. Myocardial necrosis was produced by injecting 40% formalin into the ventricular walls of 21 open-chest mongrel dogs. The injections were made in the inferior wall of the left ventricle in eight dogs (Group A) and in the inferior wall of the right ventricle in 13 dogs (Group B). Analysis of vectorcardiographic QRS loops obtained before and two hours after the injections revealed that both left and right ventricular necrosis resulted in a decrease in: maximum inferior amplitude, inferior amplitude at 10 and 20 msec. and maximum frontal plane angle. In Group A, six dogs had counterclockwise initial forces in the frontal plane before the injections and these became clockwise following the injections. In Group B, nine dogs had counterclockwise initial forces in the frontal plane before the injections and these remained counterclockwise following the injections. The only consistent QRS change in scalar ECGs that occurred after the injections was the development of small Q waves in the six dogs in Group A that manifested clockwise initial forces in the frontal plane. The VCG performed in serial fashion may be more sensitive than the 12 lead ECG for detecting right ventricular inferior wall necrosis in the experimental animal. Application of these findings to the diagnosis of myocardial infarction in humans requires further investigation.

Animals↗
PubMed1975

Effects of coronary artery ligation and release and perfusion with glucose on cardiac energy metabolism in dogs.

Adenosine triphosphate (ATP), glycogen, and inorganic phosphorus (Pi) were assayed in myocardial tissues obtained from beating dog hearts subjected to the following procedures: Group 1. Ligation of anterior descending coronary artery(AD) for 60 min. Group 2. Perfusion of the AD with 20 mM glucose in Ringer's solution containing 1 mU regular insluin/ml, for 60 min. Group 3. Ligation of the AD for 60 min, followed by release of the ligature with re-establishment of blood flow for 30 min. Group 4. Perfusion of the AD with 20 mM glucose in Ringer's solution containing 1 mU/ml regular insulin for 60 min, followed by re-establishment of blood flow for 30 min. Samples from normal myocardium (N zone) and from the area supplied by the AD (I zone) were simultaneously obtained and the level of metabolites compared. In all four groups, ATP was significantly lower in I than N zone. However, ATP values were lower in N zone in group 1 as compared with the other groups (p less than 0.05) and higher in I zone in group 3 versus groups 1 and 2 (p less than 0.05). Glycogen was lower in I than N zones to a similar degree in all the groups. However, it was higher in the I zone in group 3 than in group 1 (p less than 0.05). Pi was significantly higher in I zone versus N zone only in group 1 (p less than 0.05). These data suggest that, the the beating dog heart, ATP and glycogen preservation in a myocardial segment rendered ischemic for 1 hour is best achieved by re-establishing circulation. Glucose infusion into the ischemic segment did not contribute significantly to the ATP stores in that segment but may have exerted a protective effect on the nonischemic zones, possibly by providing a high glucose level in the circulating blood. This protection was equally well achieved by release of the ligature with or without prior glucose infusion. The increase in Pi in the ischemic zone in the dogs with coronary ligation only is probably related to accumulation of the ion under ischemic and hypoxic conditions.

Adenosine Triphosphate↗