PubMed Health⌕ Search

Biomedical subjects

J G Mohler

Publications and source records attributed to J G Mohler.

At least 19 recordsLinked to original sources
PubMed1995

Excess PTH in CRF induces pulmonary calcification, pulmonary hypertension and right ventricular hypertrophy.

Calcification of the lungs occurs in chronic renal failure (CRF) and may adversely affect both pulmonary and right ventricular function. The present study examined the role of excess parathyroid hormone (PTH) in the genesis of pulmonary calcifications in dogs with experimental CRF and evaluated calcium content of lungs, diffusing lung capacity (DCO), mean pulmonary artery pressure (MPAP), right ventricular pressure (RVP), and right ventricular hypertrophy (RVH) in six normal, six with CRF, and six thyroparathyroidectomized (CRF-PTX) dogs. CRF-PTX animals were maintained normocalcemic and euthyroid. The degree and duration of CRF were not different between the two groups with CRF. The mean value of the serum PTH in CRF dogs was 166 +/- 42 microliters Eq/ml, but was undetectable in CRF-PTX animals. Thallium scan provided evidence consistent with RVH in CRF dogs but not in CRF-PTX animals. Calcium content of lungs was markedly elevated in CRF dogs (7656 +/- 1657 mg/kg dry wt) but modestly increased in CRF-PTX (1057 +/- 117 mg/kg dry wt) as compared to normal (673 +/- 34 mg/kg dry wt). RVP and MPAP were significantly (P < 0.01) higher and DCO significantly lower in CRF dogs than in normal or CRF-PTX animals. These parameters were not different in the latter two group of dogs. In three additional dogs with CRF of one year duration which were followed for an additional year after parathyroidectomy, these abnormalities were corrected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Morning reduction of cerebral vasomotor reactivity.

We measured cerebral vasomotor reactivity during normoventilation, hyperventilation (hypocapnia), and breathing of 6% CO2 (hypercapnia) in 20 normal subjects during the hours of 6 to 8 AM, 1 to 3 PM, and 7 to 9 PM. Cerebral vasomotor reactivity was calculated, using transcranial Doppler, as percent change in the mean blood flow velocity of the middle cerebral artery per mm Hg change in end-tidal CO2 during hypocapnia and hypercapnia. Vasomotor reactivity during hypercapnia was lower in the morning (1.72 +/- 0.66 %/mm Hg) than in the afternoon (2.34 +/- 0.74 %/mm Hg, p < 0.01) and evening (2.31 +/- 0.56 %/mm Hg, p < 0.001). Vasomotor reactivity during hypocapnia did not vary significantly during the three periods (2.34 +/- 0.59 %/mm Hg in the morning, 2.43 +/- 0.51 %/mm Hg in the afternoon, and 2.26 +/- 0.52 %/mm Hg in the evening). This reduced morning response to hypercapnia suggests diminished vasodilator reserve during this period, and may be related to the increased stroke risk during the morning hours.

Adult↗
PubMed1993

Arterial oxygen content and age are determinants of middle cerebral artery blood flow velocity.

BACKGROUND AND PURPOSE: Transcranial Doppler blood flow velocities are inversely related to age and hematocrit, but the relative importance of age, oxygenation, and hemorheological factors has not previously been examined. We evaluated the relative contributions of these factors to middle cerebral artery blood flow velocity in adults with chronic renal failure, a population subject to significant fluctuations in hematologic profile. METHODS: Twenty-six subjects were studied, with arterial shunt blood sampled at the time of transcranial Doppler before dialysis. Twenty subjects from the original cohort were studied twice to examine the effects of intraindividual changes in blood oxygenation and rheology on Doppler velocities. RESULTS: Age (r = -.61, P < .001), high-shear viscosity (r = -.46, P < .02), and arterial oxygen content (r = -.44, P < .05) were all inversely related to middle cerebral artery blood flow velocity. Age was the strongest velocity predictor, accounting for 37% of variance by simple regression analysis. Intraindividual change in arterial oxygen content explained most (54%) of the middle cerebral artery blood flow velocity variation between studies (r = -.74, P < .001). Multiple regression analysis showed that inclusion of additional variables could not account for more velocity variation than change in arterial oxygen content alone. CONCLUSIONS: In this population, age and arterial oxygen content were the most important determinants of interindividual middle cerebral artery blood flow velocity variance and intraindividual middle cerebral artery blood flow velocity variation, respectively.

Adult↗
PubMed1991

The effect of postural change on the coefficient of diffusion in sarcoidosis patients.

Granulomatous angiitis is common in sarcoidosis. To test the hypothesis that patients with sarcoidosis have an impaired ability to recruit or to distend the pulmonary vascular bed, the postural change in the coefficient of diffusion (ratio of DCO to alveolar volume) for carbon monoxide was measured in 20 patients with sarcoidosis and in 10 normal subjects. The normal control group increased the coefficient of diffusion (KCO) by 12.8% (p, 0.05), when values at sitting position were compared to values at supine position. The sarcoidosis group did not significantly increase the coefficient with change in position. The absence of an increase in the coefficient of diffusion (KCO) in sarcoidosis with change in position may indicate vascular involvement.

Adult↗
PubMed1991

Effects of water immersion on cardiac output of lean and fat male subjects at rest and during exercise.

To investigate the combined effect of water immersion (WI) and lean body mass on cardiac output (Q), 12 healthy young men, 6 lean (fat less than 9%) and 6 fat (fat greater than 18%), were studied at rest and during steady state exercise approximating 30-40% Vo2 max under three experimental conditions. There were on land at 24 degrees C (LND), and immersed in water at 33-34 degrees C to hip level (HIP), and to the xiphoid (XIP). Metabolic measures were determined during 30-s periods from the average breath measurements. Mixed venous PCO2 (PVCO2) was estimated using rebreathing equilibration technique. Cardiac output was calculated by the indirect Fick's principle. In the lean individuals the average Q rose from a resting value of 5.43 +/- 0.43 (LND) to an exercise value of 7.25 +/- 0.40 L/min (XIP), and from resting value of 5.62 +/- 0.40 to an exercise 6.47 +/- 0.5 L/min in the fat individuals. During exercise, the associated increase in Q with increasing WI was significantly (p less than 0.05) higher compared with the land experiments. Inspection of the mean profile corresponding to this increase indicated that an increase in the level of immersion results in a significant (p less than 0.05) increase in the average Q for the lean group. For the fat group, the average Q was significantly (p less than 0.05) larger only at XIP level. At rest, heart rate dropped from 67 +/- 3.36 (LND) to 60 +/- 4.13 (XIP), and from 79 +/- 3.73 to 73 +/- 4.10 BPM for the lean and fat group, respectively. MANOVA analysis showed a significant (p less than 0.05) interaction between WI and group membership, indicating that the effect of WI is significantly different between the two groups. These data indicate that the change in central blood volume with WI depends, in part, on the lean mass of the body.

Adult↗
PubMed1989

Chronic diaphragmatic hernia. A difficult diagnosis.

Chest pain is commonly caused by disorders of the heart, lungs, and chest wall. Pinpointing the exact cause is often a diagnostic challenge. In this article, the authors describe the evaluation and treatment of a patient with sharp chest pain of unusual origin.

Chest Pain↗
PubMed1989

Effect of long-distance running on bone mass in women.

The effect of long-distance running on bone mass was assessed in 10 premenopausal and 9 estrogen-deprived postmenopausal women and compared to that in closely matched sedentary control women. Vertebral trabecular bone density (VBD) was determined by computed tomography and radial cortical bone density (CBD) by single-photon absorptiometry. Physical fitness was assessed by determining maximal oxygen consumption (VO2max) on a treadmill run to exhaustion. VBD was 183 +/- 7 mg/cm3 and VO2max was 48 +/- 1 ml/kg per minute in young women runners and 163 +/- 8 mg/cm3 and 32 +/- 2 ml/kg per minute in sedentary young women. A positive correlation was noted between VBD and VO2max in these groups (r = 0.509, p less than 0.03). Despite a significantly higher VO2max in postmenopausal women runners compared with sedentary controls (37 +/- 2 versus 24 +/- 2 ml/kg per minute), VBD was identical (112 +/- 5 versus 111 +/- 5 mg/cm3) and no correlation was seen between VBD and VO2max (r = 0.187, p = 0.457). Radial cortical bone density was not different between the runners or sedentary groups in young women (0.738 +/- 0.01 versus 0.732 +/- 0.1 g/cm2) or postmenopausal women (0.617 +/- 0.3 versus 0.665 +/- 0.4 g/cm2). These results suggest that although physical fitness enhances vertebral bone density in premenopausal women, it does not appear to prevent age- and/or sex steroid deficiency-induced bone loss in postmenopausal women.

Adult↗
PubMed1987

Nonautocatalytic methemoglobin formation by sodium nitrite under aerobic and anaerobic conditions.

Aerobic exposure of human hemoglobin in 1:1 molar ratio to sodium nitrite induced an immediate and progressive formation of methemoglobin. Neither lag nor autocatalytic phases were observed, contrary to what was seen when diluted hemoglobin in buffered solutions was used. Hemolyzed whole blood, washed red cells with their plasma replaced by saline, and whole blood were exposed to identical sodium nitrite concentrations. In the presence of oxygen, the speed of methemoglobin formation was three to four times faster in the hemolyzed and plasma-free samples than in whole blood. The maximum rate was reached within the first minute of the reaction. Restoring plasma to washed red cells reduced the rate to that of whole blood; restoring plasma to hemolyzed red cells had no effect on rate. We advance the hypothesis that sodium nitrite or its derivatives form a complex with some element of the blood plasma which slows the passage of nitrite through the red cell membrane without hindering the oxidative capacity of the nitrite. With no free oxygen present, whole blood, washed red cells in saline, and hemolyzed blood all showed a similar rate of methemoglobin formation when exposed to a 1:1 molar ratio of sodium nitrite. The presence of nitrosylhemoglobin formed in the anaerobic reaction seems to be a for the lack of changes seen in the reaction.

Carbon Dioxide↗
PubMed1987

Failure of the serum CO2 determined by automation to estimate the plasma bicarbonate.

In the daily care of pulmonary disease patients, we have often encountered large differences in the bicarbonate value calculated from blood gas determination pCO2 and pH, and the serum CO2 obtained from the Dupont Automatic Clinical Analyzer (ACA). Realizing that many clinicians utilize the automated measurement of serum CO2 ([CO2]s) in place of blood gas determinations, we felt it necessary to analyze paired sets of ACA [CO2]s and blood gas bicarbonate values ([HCO3-]p) for variations which might lead to clinically significant differences in interpretation. A study of 1,841 patient samples, matched by date and within +/- 2 hours of sampling, and supported by a thorough chart review of 100 randomly selected patients, indicates that a statistically significant difference, which is unrelated to apparent changes in the patient clinical status, does exist. Evaluation of pK changes due to temperature failed to correct these differences in serum CO2 and plasma bicarbonate. Based on the limited information available in the literature, as well as the strict quality control measures utilized in the measuring of [CO2]s using the ACA method and the measurement of bicarbonate by blood gas determination, we have concluded that the differences in the [CO2]s and [HCO3-]p can only be related to erroneous assumptions about the method of measuring [CO2]s by the ACA or other automated methods as well as manual techniques of back titration.

Acid-Base Equilibrium↗
PubMed1986

Proficiency testing materials for pH and blood gases. The California Thoracic Society experience.

The California Thoracic Society Blood Gas Proficiency Testing Program distributed ampules from three separate lots of quality control products every three months as unknowns to participating clinical (survey) laboratories and ten selected reference laboratories. For eight quarters, aqueous buffers were distributed. For each lot, PCO2 and pH measurements varied within narrow ranges between laboratories. Concurrently, the PO2 measurements varied widely between reference laboratories as well as survey laboratories, but varied minimally when repeatedly assessed on each reference laboratory machine. Change to a fluorocarbon-containing emulsion as a testing medium resulted in a significant reduction in within model and overall variability for PO2. We attribute this reduction in variability to the higher O2 content and decreased temperature sensitivity for PO2 of the fluorocarbon-containing emulsion. Because we have no evidence that the magnitude of the interinstrument differences in PO2 found with these materials would be found with fresh human blood we recommend that regulatory agencies use the results of proficiency testing for PO2 cautiously.

Blood↗
PubMed1985

Effects of exposure of blood hemoglobin to nitric oxide.

The effect of oxygen exposure on nitrosylhemoglobin of whole human blood or its buffered solution has been determined. The amount of methemoglobin formed was determined by an anaerobic modification of the Evelyn-Malloy method; 59% of the total hemoglobin of whole blood was oxidized to methemoglobin in the first 15 min of the oxygen exposure and 78% of the total hemoglobin was oxidized after 120 min of oxygen exposure. Similar results were obtained when nitrosylhemoglobin buffered solutions were exposed to the oxygen of the air. A comparison of the present in vitro results with these obtained by injecting nitric oxide into the rat peritoneal cavity and its implications are discussed.

Blood↗
PubMed1983

In vitro methemoglobin formation in human blood exposed to NO2.

The in vitro formation of methemoglobin in human blood was determined for various NO2 concentrations and exposure times. Blood was exposed either to measured amounts of NO2 in air or to a continuous flow of known concentrations of NO2 in air. CO2 was added to the gas phase to maintain pH and PCO2 in a normal range. Exposure to 45 ppm NO2 oxidized 95% of the total hemoglobin (THb) in 5 hr. Six ppm NO2 oxidized 17% of THb in 3 hr. Differences between in vitro and in vivo NO2 results are discussed.

Dose-Response Relationship, Drug↗
PubMed1979

Estimating a distribution's central moments: a specific tidal ventilation application.

A method is presented for extracting central moments of a distribution from data generated by the distribution over a known kernel. It is applied to the problem of the specific tidal ventilation in the lung in the multiple-breath N2-washout setting, and we found that in estimating the mean and variance, the method accurately recovers from test data those values characteristic of a test distribution. Some preliminary results on normal subjects are shown.

Humans↗
PubMed1979

Pulmonary emboli followed total hip arthroplasty: incidence study.

We compared twenty-five total hip-arthroplasty patients with twenty-five patients who underwent other operations on the lower extremity, with regard to evidence of pulmonary embolism as determined preoperatively and postoperatively from lung perfusion scans, ventilation scans, and pulmonary angiography. Blood gases and serum enzymes also were studied. The over-all incidence of pulmonary embolism was 6 per cent, despite the absence of clinical evidence of that complication. Abnormalities in scans and blood studies were common preoperatively, so that the diagnosis often depended on the detection of additional abnormalities postoperatively.

Female↗
PubMed1977

Adaptation to short-term respiratory effects of ozone in men exposed repeatedly.

To investigate whether adaptation which modifies some acute effects of ozone (O3) exposure can develop in humans, six male volunteers with respiratory hyperreactivity were exposed in a controlled environment chamber to 0.5 ppm O3 2h/day for 4 successive days under conditions stimulating ambient pollution exposures. One subject showed little measurable response, while five showed function decrement on exposure days 1-3 which was largely reversed by day 4. Symptom responses generally paralleled the physiological responses. These results suggest that at least some humans adapt to O3 exposure at concentrations occurring in severe community air pollution episodes, to the extent that obvious acute respiratory effects are prevented. Other adverse effects of O3 may not be prevented by this adaptation.

Adaptation, Physiological↗