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J Geiser

Publications and source records attributed to J Geiser.

9 recordsLinked to original sources
PubMed1991

Lung diffusing capacity and red blood cell volume.

The aim of this study was to test whether a large surface to volume ratio of the red blood cells is advantageous for O2 transfer in lungs. Suspensions of washed large (human) and small (sheep) red blood cells were used to perfuse in random order isolated cat lungs (n = 7). The lungs were kept at 27 degrees C, ventilated with 1.0 l/min and perfused with 110 ml/min. Hemoglobin concentration was 70 g/l. Assuming an inhomogeneous lung with an alveolar dead space compartment, pulmonary diffusing capacity for O2 (DLO2) was 0.53 +/- 0.10 ml.min-1.mmHg-1 (mean +/- SD) when perfusing with sheep red cells and 0.52 +/- 0.13 with human red cells. On the basis of a lung model with a low VA/Q and a high VA/Q compartment the values were 0.86 and 0.93. Thus, DLO2 was not larger with smaller red blood cells, i.e. with higher red cell surface area per blood volume. Possible explanations for this unexpected result are discussed.

Animals↗
PubMed1989

Gas transfer in isolated lungs perfused with red cell suspension or hemoglobin solution.

Rapid mixing experiments have shown that the reaction between oxygen and hemoglobin is faster in hemoglobin solutions than in red cell suspensions. In this study we tested whether this observation can also be made in the lung. Excised rabbit lungs were perfused either with washed human red cell suspensions or with hemoglobin solutions, each with 50 g hemoglobin/L, and steady-state diffusing capacities (DLO2) for oxygen elimination measured. Mean settings were a temperature of 29.5 degrees C of the inflowing and outflowing perfusate of the lung, a total ventilation of 1.7 L.min-1, and a perfusion rate of 116 ml.min-1. Under those conditions resulted a DLO2 with hemoglobin solution of 0.68 +/- 0.18 ml.min-1.mm Hg-1, and a significantly lower value of 0.50 +/- 0.06 ml.min-1.mm Hg-1 with red cell suspension (P less than 0.01). An extraerythrocytic diffusing resistance, formed by a plasma layer and/or arising from a dynamic diffusion boundary layer, which is also known as unstirred layer, could explain the lower value with red cell suspensions.

Animals↗
PubMed1989

Resistance of mammalian red blood cells of different size to hypertonic milieu.

1. The resistance of different mammalian red blood cells (RBCs) to hyperosmotic environments was studied. RBCs of six mammalian species were exposed to 10 increasingly hyperosmotic NaCl solutions for 24 hr at 5 degrees C. 2. The osmolality at which the amount of liberated haemoglobin reached a preset level (e.g. 3-4% of the total haemoglobin) showed a linear correlation with negative slope with RBC volume. This indicates that small RBCs are more resistant to hyperosmotic milieu than large ones. 3. A similar relation can be found from literature data when maximal urinary tonicities are plotted as a function of RBC volume, i.e. animals with the ability to produce highly concentrated urine have small RBCs. 4. RBC volume and maximal urinary tonicity in mammals are therefore tightly linked. Future research will have to show whether this correlation is fortuitous or not and whether, as can be speculated, RBC size is directly or indirectly regulated by the kidney.

Adult↗
PubMed1986

Effects of altering dead space volume on respiration and air sac gases in geese.

Dead space volume (VD) was altered in spontaneously breathing, anesthetized geese from values far above (about 115 ml) to those far below (about 3 ml) the normal VD (approximately 40 ml). Respiratory gases were measured in cranial (CrS) and caudal air sacs (CdS) and in blood. The major findings were as follows: Ventilation increased linearly with VD, by increases in tidal volume (VT) at constant breathing rate (fresp); effective parabronchial ventilation, (VT-VD) X fresp, remained constant and so did arterial blood gases. No changes occurred in CrS gas composition. CdS PCO2 declined with decreasing VD, and the respiratory exchange ratio increased, reaching values above unity at the lowest VD. The gas composition in CrS, and particularly its relation to end-expired gas composition, is in agreement with current models of the gas flow pattern in the avian lung. The PCO2 values in CdS are higher than expected by simple models, e.g. by dead space re-inhalation. Neopulmonic gas exchange and incomplete gas mixing are suggested to contribute significantly to the gas composition of CdS.

Air Sacs↗
PubMed1979

Pulmonary O2 diffusing capacity estimates from assumed log-normal VA/Q distributions.

Steady-state pulmonary gas exchange has been measured in hypoxia in 33 mongrel dogs with the aim of comparing DLO2 estimates obtained with three procedures differing by the models assumed for functional inhomogeneity. In the first procedure the lung was assumed to be homogeneous and the corresponding DLO2 estimate was 15 mumol . min-1. Torr-1 . kg-1. In the second procedure, which is the one commonly used in respiratory physiology, alveolar dead space was considered as the unique form of functional inhomogeneity and the corresponding DLO2 estimate was 31 mumol . min-1. Torr-1 . kg-1. In the third procedure, which has been specially worked out for this study, functional inhomogeneity was represented by a log-normal distribution of the VA/Q ratios and the corresponding DLO2 estimate was 50 mumol . min-1 . Torr-1 . kg-1. The relation between the DLO2 estimates by the second and by the third procedures was found to depend upon the blood pH. This could be explained on the basis of the effects of acidosis on the blood capacitances for O2 and for CO2. Analysis suggests that in hypoxia where normally the O2 capacitance is about half the CO2 one, the third procedure yields DLO2 estimates about twice as large as those obtained by the second one.

Animals↗
PubMed1978

[Unrecognized hyperthyroidism in hospital patients. Analysis of clinical symptoms compared to aged euthyroid goiter patients].

During a 14-month period hyperthyroidism has been diagnosed in 39 of 2916 inpatients of a general medical service. Graves' disease was present in only 8 cases. 21 patients had solitary autonomous nodules or multiple autonomous nodules (toxic multinodular goiter). In 10 patients the type of hyperthyroidism could not be established. The referring practitioner suspected hyperthyroidism in all 8 patients with Graves' disease, but in only 5 of the 31 remaining cases. The relative rarity of Graves' disease in inpatients reflects the fact that this form of hyperthyroidism is easily recognized by the practitioner and treated on an out-patient basis. Graves' disease patients and those with autonomous solitary or multiple nodules were of comparable age and had an identical serum free-thyroxin. Thus, neither higher age nor lower thyroxin is responsible for the atypical clinical presentation of autonomous nodules. A comparison with age- and sex-matched carriers of euthyroid goiters identified weight loss, resting pulse rate over 90 and auricular fibrillation as reliable clinical features. A thyroid function test is therefore indicated in every patient with a goiter and one of the three above clinical findings.

Adenoma↗
PubMed1978

[Importance of thyroid diseases in internal medical hospital].

Retrospective analysis of 2627 and prospective analysis of 289 inpatients (mean age: 57 years) of the Department of Internal Medicine, University of Berne, disclosed euthyroid goiter in 33.9%. 65% of the patients had urinary iodine excretion below 100 microgram per gram creatinine. Thus, iodination of salt (raised to 10 mg potassium iodide per kg in 1962) is still inadequate. 1.4% of the inpatients had hyperthyroidism. Hypothyroidism was diagnosed in 0.5% of the inpatients, which is about three times less than in comparable prospective English studies. The finding raises the possibility that cases of hypothyroidism have been frequently missed. Antibodies against thyroglobulin and/or microsomal antigen were present in 8.5% of 105 goiter patients and 4.0% of 124 patients without goiter. This is a definitely lower incidence than has been reported in comparable English populations and confirms reports from other Alpine endemic goiter areas. Among the 2916 patients of the entire study only 3 cases (0.1%) of clear-cut chronic lymphocytic (Hashimoto) thyroiditis were found.

Autoantibodies↗