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Biomedical subjects

R S Kronenberg

Publications and source records attributed to R S Kronenberg.

At least 37 records · Page 2Linked to original sources
PubMed1980

Increased hypoxic ventilatory drive due to administration of aminophylline in normal men.

We evaluated the effects of intravenous administration and five days of oral administration of aminophylline on hypoxic and hypercapnic ventilatory drives in seven normal men. Serum levels of theophylline were 13.2 micrograms/ml +/- 1.0 micrograms/ml (mean +/- SD) after intravenous administration of aminophylline and 8.8 micrograms/ml +/- 1.7 micrograms/ml after oral administration of aminophylline. Aminophylline had no effect on the slope of the line for carbon dioxide response or on hypoxic ventilatory drive, measured at resting alveolar carbon dioxide tension (PACO2). Hypoxic ventilatory drive was significantly increased (P < 0.025) after intravenous administration of aminophylline when the PACO2 was raised to the control level before aminophylline. Intravenously administered aminophylline shifted the intercept of the line for carbon dioxide response from 40.7 +/- 2.3 to 32.9 +/- 4.6 mm Hg (P < 0.005) and lowered the resting PACO2 from 38.3 +/- 1.8 to 33.7 +/- 2.1 mm Hg (P < 0.005). Similar but smaller changes were seen after oral administration of aminophylline. There was a significant correlation between end-tidal carbon dioxide tension and the serum level of theophylline (P < 0.001), indicating that aminophylline stimulates ventilation in a dose-dependent fashion. This increase in ventilation is due in part to an increase in hypoxic ventilatory drive.

Administration, Oral↗
PubMed1978

Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity.

To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude.

Adaptation, Physiological↗
PubMed1977

Complement and leukocyte-mediated pulmonary dysfunction in hemodialysis.

During hemodialysis, cardiopulmonary decompensation may appear in uremic patients, possibly caused by plugging of pulmonary vessels by leukocytes. In 34 patients we noted leukopenia (20% of initial levels) during hemodialysis that in 15 was associated with impaired pulmonary function. When we infused autologous plasma, incubated with dialyzer cellophane, into rabbits and sheep, sudden leukopenia and hypoxia occurred, with doubling of pulmonary-artery pressures and quintupling of pulmonary-lymph effluent. Histologic examination showed severe pulmonary-vessel-leukostasis and interstitial edema. The syndrome was prevented by preinactivation of complement but was reproduced by infusions of plasma in which complement was activated by zymosan. Thus, acute pulmonary dysfunction from complement-mediated leukostasis may play a major part in the acute cardiopulmonary complications of cellophane-membrane hemodialysis.

Adolescent↗
PubMed1977

Acute respiratory failure and obesity with normal ventilatory response to carbon dioxide and absent hypoxic ventilatory drive.

We measured hypoxic and hypercapnic ventilatory drive in a 64 year old woman with acute respiratory failure, congestive heart failure and obesity when she was in remission. She had a ventilatory response to carbon dioxide (CO2) comparable to that in six obese women without hypoventilation but no ventilatory response to hypoxia or to vital capacity breaths of 15 per cent CO2 in N2. Following weight loss, her ventilatory response to CO2 increased but hypoxic ventilatory response to CO2 increased but hypoxic ventilatory drive remained absent. These findings indicate that attenuation of hypoxic ventilatory drive caused by loss of peripheral chemoreceptor function can be a predisposing factor in the development of acute respiratory failure associated with obesity.

Body Weight↗
PubMed1977

Hypoxic ventilatory response in subjects with normal and high oxygen affinity hemoglobins.

It has still not been shown unequivocally whether a decrement of arterial oxygen content or tension governs the ventilatory response to hypoxia. In an attempt to discriminate between the two possibilities, we have measured the ventilatory response to isocapnic progressive hypoxia in two healthy children with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in their age- and sex-matched normal siblings. Hypoxic ventilatory response was identical in all subjects, there being no difference in minute ventilation at PAo2 = 40 mm Hg or in k (decrement of PO2 required to increase ventilation by a factor of 2.718). In contrast, at PAo2 = 40 mm Hg, hemoglobin oxygen saturation decreased markedly in controls but only slightly in high affinity subjects. Furthermore the increase in heart rate at PAo2 = 40 mm Hg was significantly less in high affinity subjects, suggesting a concomitant difference in oxygen delivery. Thus, with identical decrements in PAo2 but widely divergent changes in arterial oxygen content and oxygen delivery, controls and high affinity subjects showed virtually identical ventilatory response to hypoxia. We conclude that decrements of oxygen tension are the major stimulus for hypoxic ventilatory response.

Adolescent↗
PubMed1976

Frequency dependence of regional lung clearance of 133Xe in normal men.

We measured the one-half time of 133Xe washout from the whole lung and from 9 horizontal lung regions in 6 normal men during normal breathing and at 50 breaths/min. The diaphragm was located with a contour map prior to the selection of the 9 horizontal regions. Artifacts caused by the tissue solubility of 133Xe were reduced by expressing regional clearance relative to whole lung clearance. During normal breathing there was a progressive increase in the relative clearance of 133Xe from the lung apex to the base when each region was compared to the lung as a whole. At 50 breaths/min, relative clearance increased from the lung apex only for about 18.5 to 20 cm. At that point, the relative clearance rate of the horizontal regions began to fall and at the lung base was slower than that of the whole lung. These results are consistent with the concept that dependent lung regions have longer time constants than regions at the top of the lung.

Adult↗
PubMed1976

Study of the surface secretion of the bronchiole using radioautography.

The purpose of the present study was to obtain further information regarding the chemical nature and cell of origin of the surface secretion of the bronchiole using radioautography after the injection of labeled leucine, glucosamine, galactose. Rat lungs were perfused with mammalian Ringer's solution with added albumin. A 10-min pulse of L-leucine labeled with hydrogen-3 was administered, followed by perfusion with nonradioactive solution for 15 min to 4 hours. Similar studies were performed with [3H] glucosamine and [3H] galactose. Heavy labeling of the Clara cells of bronchioles was obtained after injection of [3H] L-leucine. Labeling of alveolar wall cells was also obtained. Labeling of the surface of the bronchiole was much heavier than the labeling of the surface of the alveoli. No specific labeling of bronchiolar cells was obtained with [3H] glucosamine and [3H] galactose. The results provide added evidence for the protein nature of the surface layer of the bronchiole and for the Clara cell as its cell of origin.

Animals↗
PubMed1975

Normal chemoreceptor function in obesity before and after ileal bypass surgery to force weight reduction.

Ventilatory responses to progressive isocapnic hypoxia and rebreathing of carbon dioxide in oxygen were determined in four obese women before and approximately 1 year after ileal bypass surgery to force weight reduction. None of the patients was hypoventilating and all had normal pulmonary function tests. The ventilatory responses to hypoxia were normal before surgery and were not effected by weight reduction. The ventilatory responses to hypercapnia did not change in slope but a shift of the carbon dioxide response line toward a lower arterial carbon dioxide tension occurred in two subjects after weight reduction. We conclude that obesity per se does not necessarily cause loss of hypoxic ventilatory drive.

Adult↗
PubMed1974

Dual camera studies of pulmonary function with computer processing of data.

Xenon 133 and 2 scintillation cameras arranged to view both anterior and posterior lung fields are being used routinely for evaluation of pulmonary function. Scintiphotograms are obtained from both cameras throughout the course of both perfusion and ventilation portions of the study. In addition, data from both cameras are digitized and stored on line in a dedicated computer for further analysis. Computer processing of data permits quantitative information to be obtained on perfusion, ventilation and clearance of the radioactive gas from selected regions of the anterior and posterior lung fields. Ventilation-perfusion ratios and washout times are likewise calculated by computer.

Computers↗