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Biomedical subjects

R L Jensen

Publications and source records attributed to R L Jensen.

At least 19 recordsLinked to original sources
PubMed1992

Local induction of tumor necrosis factor as a molecular mechanism of mucosal damage by gonococci.

Tumor necrosis factor (TNF) is an endogenously produced cytokine that plays a critical role in mediating septic shock and multi-organ failure, but previous studies of the role TNF in disease have not examined its role in mucosal disease processes. In an experimental model of acute gonococcal salpingitis, gonococcal infection of human fallopian tube mucosa resulted in increased mucosal production of TNF. Recombinant human TNF-alpha damaged fallopian tube mucosa in a dose-response manner and produced epithelial damage with the same ultrastructural features as those observed in gonococcal infection. Blocking production of TNF during gonococcal infection diminished the extent of damage to fallopian tube mucosa. In addition to mediating systemic disease, such as septic shock, TNF is also produced locally, and can play a critical role in mediating mucosal disease processes, such as acute gonococcal salpingitis.

Dexamethasone↗
PubMed1992

Evaluation of accuracy and reproducibility of peak flowmeters at 1,400 m.

Peak flow meters provide physicians and patients with objective measures about changes in pulmonary obstruction. We evaluated eight models of peak flowmeters and measured their accuracy and reproducibility with methods recently recommended by the National Asthma Education Program (NAEP). Waveforms from the American Thoracic Society's spirometer testing set were used to drive a computer-controlled syringe. Testing was done at Salt Lake City at an altitude 1,400 m. It appears that the original Wright peak flowmeter has been used as the "de facto" standard. We found that the original Wright peak flowmeter overestimated flows in its midrange; and, as a consequence, most of the other peak flowmeters also overestimated peak flows. The overestimation of peak flows may have been understated because of the 1,400-m altitude testing site. To the credit of the instrument manufacturers, we were pleasantly surprised with the quality, accuracy, and reproducibility of presently available peak flowmeters; however, as a result of our testing, we suspect that with little effort, manufacturers of peak flowmeters could improve the accuracy of their devices. Standardized testing methods and equipment should make the task of peak flowmeter design, manufacture, and testing even easier. We trust that manufacturers of peak flowmeters will respond appropriately and improve their instruments.

Adult↗
PubMed1991

A new approach to rowing ergometry: establishing exercise intensity relative to maximum force output.

The present experiment evaluated a new approach to establish exercise intensity during hydraulic rowing ergometry. In contrast to the traditional approach where exercise intensity is augmented by systematically increasing workload, the new procedure increments the intensity of exercise while maintaining a constant percentage of maximum force output. Ten college females exercised on a hydraulic rower that allowed for control of rowing speed and resistance. The new method to establish work intensity was to row at a cadence of 30 c.min-1 at a force output equal to 50% of maximum rowing force at each setting determined dynamically prior to testing. Two protocols were used for the maximum tests on the hydraulic rower. Row 1 was a 17-min, six-stage, incremental continuous row test performed at increasingly difficult settings from easy (setting 1; 603 N) to difficult (setting 6; 893 N). Row 2 was identical to row 1 until 15 min when resistance was reduced to setting 2 (658 N) for "allout" effort during the last 2 min. During this time, cadence declined from 30 c.min-1 to 19.4 c.min-1 at dial setting 6 and increased to 35.4 c.min-1 at dial setting 2. Both rowing protocols were compared to maximal physiological responses during treadmill running (TM). Compared to TM, both rowing protocols elicited significantly lower maximum oxygen uptake (VO2max; P less than 0.05; row 1 = delta 29.0% and row 2 = delta 12.9%) and maximum heart rate (HRmax; P less than 0.05; row 1 = delta 12.9% and row 2 = delta 6.7%). Maximum ventilation (VEmax) during row 1 was also lower by 30.4% than TM (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Energy Metabolism↗
PubMed1991

Open lung biopsy does not correlate with pulmonary function after the adult respiratory distress syndrome.

Abnormalities of pulmonary function occur following the adult respiratory distress syndrome (ARDS). To determine if open lung biopsy (OLB) during ARDS predicts late pulmonary function abnormalities, we examined nine survivors of ARDS who had OLB during ARDS. Open lung biopsy was performed within two weeks of the diagnosis of ARDS, and the following were scored by a pulmonary pathologist as to extent and severity: hyaline membranes (HM), interstitial fibrosis (IF), air space organization (AO), interstitial cellularity (IC), and type 2 cell proliferation (T2C). Pulmonary function tests performed at least one year after ARDS were also used for analysis. Percent predicted Dco, TLC, DL/VA, and FVC were regressed against extent, severity, and combined scores. No significant correlation was found despite impressive histologic abnormalities. These data suggest that the severity and extent of HM, IF, AO, T2C, or IC do not correlate with lung function following ARDS.

Female↗
PubMed1990

Adjustment of DLCO for varying COHb, and alveolar PO2 using a theoretical adjustment equation.

The diffusing capacity of the lung for carbon monoxide (DL) is affected by changes in alveolar partial pressure of oxygen (PAO2), hemoglobin concentration (Hb), and carboxyhemoglobin concentration (COHb). A number of investigators have derived empiric adjustment equations to account for changes in these variables. We evaluated an adjustment of DL for changes in COHb and PAO2 using a single equation derived from Roughton and Forster's original definitions (J. Appl. Physiol., 1957). Unadjusted DL values declined significantly with rising COHb (-0.938%/percent COHb increase, P less than 0.0001) and rising PAO2 (-0.343%/mm Hg PAO2 increase, P less than 0.0001). Adjusted measured DL using the derived equation showed no significant change with changing COHb and PAO2 levels and provides an acceptable method for adjustment of DL for the effects of varying COHb and PAO2 levels from the standard conditions of COHb% = 0, and PAO2 = 110 mm Hg. Since a similar equation has previously been used to adjust for changes in DL due to anemia, we propose to use a single equation which is theoretically derived and empirically verified to adjust DL measurements for changes in COHb, PAO2 and hemoglobin.

Carbon Monoxide↗
PubMed1990

Perioperative warfarin therapy in combined abdominal lipectomy and intraabdominal gynecological surgical procedures.

The combination of multiple surgical procedures is attractive and convenient to the patient. Increased awareness of wound healing difficulties and pulmonary complications, however, suggest caution with this approach, particularly when combining abdominal lipectomy with intraabdominal procedures. This study confirms the high risk of pulmonary emboli in patients with combined abdominal lipectomy and intraabdominal gynecological procedures. The use of perioperative warfarin may reduce the incidence of pulmonary embolism in patients who have combined abdominal lipectomy and gynecological surgical procedures, and it is not associated with increased bleeding or other postoperative complications.

Adult↗
PubMed1990

Small-sample reproducibility estimates: an example using rebreathing measurements.

We developed a statistical technique to estimate the reproducibility of a parameter from a population in which only two repeated measurements can be made in a single individual. The following data were analyzed: acetylene cardiac output (Qc), lung tissue volume (Vti), and carbon monoxide diffusing capacity (DLCO) measured by rebreathing techniques in a population of 86 healthy subjects (51 men and 35 women). Each subject was measured twice with a computerized rebreathing system using a test gas of 10% He-0.3% C18O-0.7% C2H2-25% O2-balance N2 while sitting at rest. The estimated coefficients of variation for repeated measurements were 6.8, 10.3, and 5.7% for Qc, Vti, and DLCO, respectively. Chebyshev's inequality was used to estimate the imprecision for a single measurement of these parameters and for averages of two or more repeated values. A single measurement of Qc would be within 14.2% of a "true" mean 90% of the time, whereas an average of three consecutive measurements would be within 8.2% of the true mean 90% of the time. Single measurements of Vti and DLCO were found to be within 21.7 and 12.0%, respectively, of the true mean 90% of the time. When three consecutive measurements are averaged, Vti is within 12.6% and DLCO is within 6.9% of the true mean 90% of the time. We conclude that 1) rebreathing Qc is as reproducible as other measurements of cardiac output, 2) rebreathing measurements of DLCO are as reproducible as those made by the single-breath technique, and 3) an average of two to three measurements of Vti should be made to obtain values with a reasonable degree of precision.

Acetylene↗
PubMed1990

Assessing precision and accuracy in blood gas proficiency testing.

Blood gas proficiency testing has focused on assessing the accuracy of measurement of each analyte (pH, PCO2) independently of each other. Recently, the American Thoracic Society-California Thoracic Society Blood Gas Proficiency Testing Survey distributed the same lot of ampules of proficiency testing material (a buffered fluorocarbon-containing emulsion) on three occasions within a 1-yr period, allowing us to assess the precision (reproducibility) of measurement of each analyte. Comparing 580 instruments of 13 models, we found that the precision of measurement of each analyte was positively correlated with the precision of measurement of each other analyte, and the correlation of precision between models was much stronger than precision between the individual instruments. We also found correlation of precision of each analyte with two targets for accuracy: (1) the all-instrument mean and (2) the model-specific means. Correlations were higher with the model-specific means. These findings suggest: (1) that features unique to design of each model are important in the precision of measurement of these ampules, and (2) that it would be informative to include measurements of precision with linked and cumulative ratings of analyte accuracy in proficiency testing rating systems.

Blood Gas Analysis↗
PubMed1990

Laboratory findings associated with abomasal ulcers/tympany in range calves.

The etiology of abomasal ulcers/tympany was investigated in 48 animals from 36 ranches in Wyoming and Nebraska. Results indicate that subclinical trace mineral deficiencies of copper and/or selenium exist in the range cattle in west central Nebraska and Wyoming. Etiological agents most frequently incriminated by bacteriologic cultures and/or histopathic examination were Clostridium perfringens and Campylobacter species. Histopathologic evaluation of abomasums revealed 31 of 38 cases contained abundant gram-positive bacteria associated with the damaged abomasal mucosa. Campylobacter-like organisms were demonstrated in 9 of 38 cases using the modified Dieterle stain. Clostridium perfringens was isolated in 14 of 38 cases, and Campylobacter jejuni was recovered from 5 of 38 cases.

Abomasum↗
PubMed1990

Performance evaluation of contemporary spirometers.

A comprehensive evaluation of 62 spirometers from 37 different sources was performed using a two-part protocol: calibrated syringe, and dynamic waveform testing. All testing was done with ambient air. Calibrated syringe testing examined the ability of the spirometers to accurately measure the output of a 3 L calibrating syringe under varying conditions. The accuracy, FVC volume linearity, and stability of each spirometer was determined from these data. All but five of 42 spirometers accurately measured a 3 L calibrating syringe to within +/- 3 percent. Dynamic waveform testing consisted of introducing 24 standard waveforms into the spirometer from a computer-controlled air pump. The values of FVC, FEV1, and FEF25-75% were compared to the actual values for each waveform to determine a performance rating. Only 35 (56.5 percent) of the spirometers performed acceptably when measuring the 24 standard waveforms. Nine (14.5 percent) were marginal and 18 (29.0 percent) were unacceptable. Fifty-nine (95 percent) of the 62 spirometers were computerized. Software errors were found in 25 percent of the computerized systems evaluated. Although using a 3 L syringe for quality control purposes is essential, simple testing of spirometers with a 3 L calibrating syringe for validation purposes was inadequate to assess spirometer performance when compared to dynamic waveform testing. Dynamic waveform testing is essential to accurately measure and validate acceptability of spirometer system performance.

Calibration↗
PubMed1990

Normal spirometric values in healthy Hispanic Americans.

FVC, FEV1, FEV1/FVC, and FEF25-75% were measured in 259 (116 men and 143 women) healthy nonsmoking Hispanic American volunteers from Utah and California. Linear regression equations were created for women greater than or equal to age 20 years and men greater than or equal to age 25 years using height, age, and weight as independent variables and the spirometric indices as dependent variables. Weight was a significant predictor only for female FEV1. The raw data from this study were compared with data from our previous studies in North American Indians and Salt Lake City whites with Middle European ethnic backgrounds. No differences were found for any of the age and height coefficients. The only differences found were in the comparisons of the equation intercepts (bias) for male FVC and FEV1 between data for the Salt Lake City white subjects and both Hispanic American and North American Indian men. These small biases could be explained by technical or sampling biases or they may represent small ethnic differences. Although the differences from our Salt Lake City study are small, we recommend that ethnic-specific equations be used where they are available.

Adolescent↗
PubMed1989

Impairment after adult respiratory distress syndrome. An evaluation based on American Thoracic Society recommendations.

To test the hypothesis that impairment after the adult respiratory distress syndrome (ARDS) is uncommon, we evaluated 41 ARDS survivors using ATS standards for determination of impairment. A total of 101 trials of pulmonary function tests were obtained between 1 and 388 wk after the onset of ARDS. It was possible to evaluate impairment at 1 yr or more after ARDS in 27 subjects. Eighteen of the 27 were impaired. The percentage of ARDS survivors who were impaired on the basis of FVC, FEV1, FEV1/FVC, and DLCOsb was 50.0, 61.1, 33.3, and 82.4%, respectively. Impairment was mild in 13 (72.2%), moderate in four (22.2%), and severe in one (5.6%). Smoking status had no predictive value in determining impairment. Physiologic indices of ARDS severity (maximal pulmonary artery pressure, lowest static thoracic compliance, and maximal level of PEEP) were found to be significantly different when those impaired 1 yr or more after ARDS were compared with those not impaired. Symptoms were found to have no association with impairment. We conclude that, using ATS criteria, impairment 1 yr or more after ARDS onset is common. Patient characteristics and symptoms after ARDS have no association with impairment 1 yr or more after ARDS onset, whereas physiologic indices of severity during ARDS do.

Adult↗
PubMed1989

Comparison of blood gas analyzer biases in measuring tonometered blood and a fluorocarbon-containing, proficiency-testing material.

This study was designed to test whether the interinstrument differences (biases) in analyses of the PO2 and PCO2 of the commercial fluorocarbon-containing emulsion (FCE) proficiency-testing material abc were similar in magnitude and direction to analyses of the PO2 and PCO2 at four similar partial pressures in tonometered blood. There were large differences among the 13 individual instrumental mean values for both blood and FCE at the four levels: for PO2 (average range, 10.3 mm Hg for blood and 17.0 mm Hg for FCE) and PCO2 (average range, 9.4 mm Hg for blood and 6.2 mm Hg for FCE). Although the instrumental biases for blood and FCE were approximately the same, the biases were slightly higher for FCE in measuring PO2 and slightly higher for blood in measuring PCO2. Accuracy and precision in blood measurement and precision in FCE measurement were significantly correlated among instruments for PO2 and PCO2. The biases of the nine instrument models evaluated significantly correlated with those of the same models participating in national surveys. We suggest that differences in technique, maintenance, and instrumental design rather than inherent differences in PO2 and PCO2 electrodes probably account for the demonstrable differences between instruments. The fluorocarbon-containing emulsion used is of value in proficiency testing for PO2 and PCO2.

Blood Gas Analysis↗
PubMed1989

Heritability estimates of pulmonary function.

To test the hypothesis that there is genetic control of pulmonary function parameters independent of that influencing height, we evaluated 74 pairs of asymptomatic, nonsmoking twins. FVC, FEV1, FEF25-75%, TLCsb, RVsb, Dsb, and D/VA were measured. Pulmonary function indices were adjusted for height using simple linear regression. Mean intrapair differences (unadjusted and adjusted for height) were compared using t tests of independent samples. Within pair, Holzinger's, and Falconer's heritability estimates were calculated using height-adjusted residual values. When total variances of a function parameter were statistically different between monozygotes and dizygotes, the among component heritability estimate was calculated and used as the best indicator of heritability. Following adjustment for height, no measure of pulmonary function which satisfied the requirements of the analysis was found to be significantly heritable.

Adult↗
PubMed1988

Evaluation of lung diffusing capacity by physiological and morphometric techniques.

Determinations of pulmonary diffusing capacity for CO (DLCO) by physiological and morphometric techniques have resulted in substantially different values for both DLCO and its major components. To evaluate the differences in these methods of measurement of DLCO, measurements were made under controlled conditions on isolated perfused dog lungs. Multiple gas-rebreathing techniques were used to measure DLCO, the membrane component of the diffusing capacity for CO (DmCO), and pulmonary capillary blood volume (Vc) in both anesthetized dogs and after isolation and perfusion of their lungs. The isolated perfused lungs were than perfusion fixed for morphometric analysis of the components of DLCO. The values obtained morphometrically for Vc were similar to those measured by physiological techniques. Perfusion fixation did not substantially alter the morphometric estimate of DmCO when compared with previous values obtained on inflation fixed lungs. However, the morphometric estimate of DmCO was over 10 times higher than that estimated physiologically. Analysis of the potential errors in the techniques suggests that the correct value for DmCO is substantially higher than that commonly estimated by use of physiological techniques and that the explanation for the difference is due to a number of factors that can influence the binding of CO to hemoglobin under in vivo conditions. The net effect of these factors can be represented by an unknown in each component of the Roughton-Forster relationship so that 1/DL = 1/(U1.Dm) + 1/(U2.theta Vc), where theta is the binding rate for CO to hemoglobin. Because the magnitudes of the unknown terms (U1 and U2) in the Roughton-Forster relationship are likely to be large, this relationship cannot be reliably used to determine Dm and Vc.

Animals↗
PubMed1988

Maximum respiratory pressures in morbidly obese subjects.

Maximum inspiratory and expiratory pressures were measured at residual volume, total lung capacity, and functional residual capacity in 45 morbidly obese patients who on average weighed 183% of their predicted weights. The pressures were compared to determinations made in 25 subjects of similar age whose mean weight was 99% of predicted. For both men and women, pressures generated by control subjects tended to be higher than those produced by obese patients but the differences were not statistically significant. The mean vital capacity and total lung capacity were also similar in the 2 subject groups. The results indicate that despite working constantly against a less compliant chest wall, obese patients do not increase their capacity to generate maximal respiratory pressures.

Adult↗
PubMed1988

Longitudinal pulmonary function changes in pigeon breeders.

We studied 15 subjects (14 men and one woman; seven symptomatic and eight asymptomatic) at three- to four-year intervals from 1967 through 1985 (18 years) to determine if continued pigeon antigen exposure in these groups was associated with a decline in pulmonary function greater than expected in healthy individuals. We collected immunologic studies at the initial visit, performed sequential pulmonary function studies and obtained chest radiographs. After compensating for the normal changes expected with increasing age, we found the declines in FVC, FEV1, and Dsb in the symptomatic group were nearly four times greater than expected. There was no significant difference in the decline of pulmonary function between asymptomatic subjects and the normal predicted declines with increasing age. We conclude that, if an individual has episodes of acute hypersensitivity pneumonitis, long-term exposure to pigeon antigens will result in an accelerated decline in pulmonary function.

Adult↗