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Biomedical subjects

B Rasmussen

Publications and source records attributed to B Rasmussen.

At least 73 records · Page 4Linked to original sources
PubMed1984

Hepatic drug metabolism and physical fitness.

Physical fitness, as expressed by maximal oxygen uptake (Vo2max), was measured in 14 subjects before and during physical education consisting of 4 to 8 hr of daily physical training. Mean pulse rate during training was 115 bpm. After 3 mo of physical training, Vo2max increased a mean 6% (range -5% to +23%). Corresponding mean increases in hepatic drug metabolism, as expressed by the metabolism of the model drugs antipyrine and aminopyrine, were 12% (range -12% to +59%) and 13% (range -21% to +47%). Changes in the two groups were still present 6 mo after physical education. There was only a moderately close but nonetheless significant correlation (r = 0.7) between the extent of change in Vo2max and the corresponding relative change in antipyrine metabolism during the 3-mo period of this investigation. The correlation between oxygen uptake and aminopyrine metabolism (r = 0.6) was slightly less and was not significant. Improved physical fitness associated with enhanced drug metabolism may lead to changes in drug efficacy and drug toxicity that may be clinically important in the case of drugs with low therapeutic indices.

Adult↗
PubMed1983

Time course of phenobarbital and cimetidine mediated changes in hepatic drug metabolism.

Four healthy subjects were investigated weekly for 14 weeks by the antipyrine one sample saliva test, the 48-h urinary excretion of major antipyrine metabolites and the 2-h aminopyrine breath test before, during and after stimulation and inhibition of drug metabolism with phenobarbital and cimetidine, respectively. The phenobarbital-induced enhancement of antipyrine clearance (1.33-2.03 times) and of the aminopyrine breath test (0.94-1.19 times) occurred one week after beginning drug administration and persisted for 10 days after its cessation. The cimetidine-related inhibition of antipyrine clearance (0.62-0.85 times) and of the aminopyrine breath test (0.52-0.93 times) was observed 24 h after beginning cimetidine administration and subsided within two days after the last dose. During enhancement and inhibition the clearance of antipyrine to 3-hydroxymethyl-, 4-hydroxy- and norantipyrine varied as the total antipyrine clearance. The intraindividual variation in antipyrine clearance was 6-8%, and the corresponding variation in urinary excretion of antipyrine metabolites was 10-20%. It is concluded that the influence of phenobarbital and cimetidine on hepatic microsomal enzyme activity can be monitored simply by measurement of the blood concentration of the drug. Whether this simple relationship applies to other microsomally mediated drug interactions requires further evaluation.

Adult↗
PubMed1979

An improved nitroblue tetrazolium test using phorbol myristate acetate-coated coverslips.

The endotoxin--nitroblue tetrazolium (NBT) slide test was modified by precoating coverslips with phorbol myristate acetate instead of endotoxin. The percentage of control polymorphonuclear leukocytes reducing NBT was significantly (P less than .05) greater on phorbol myristate acetate-coated coverslips (99 +/- 0.21%) than on endotoxin-coated coverslips (96+/- 1.8%). Polymorphonuclear leukocytes from patients with chronic granulomatous disease did not reduce NBT on phorbol myristate acetate- or endotoxin-treated coverslips. NBT reduction by polymorphonuclear leukocytes from proven heterozygotic carriers of sex-linked chronic granulomatous disease was intermediate between NBT reductions by those from controls and patients. A statistically significant abnormality of NBT reduction was found in polymorphonuclear leukocytes from one carrier of chronic granulomatous disease with phorbol myristate acetate-treated, but not endotoxin-treated coverslips. The phorbol myristate acetate-NBT coverslip technic is a rapid, simple, reliable way to detect deficiencies in polymorphonuclear leukocytes from patients and carriers of chronic granulomatous disease.

Chemical Phenomena↗
PubMed1979

Ventilatory and occlusion pressure response to CO2 and hypoxia with resistive loads.

Steady-state responses to hyperoxic hypercapnia and eucapnic hypoxia were measured both as minute ventilation (VE) and as inspiratory mouth occlusion pressure (P0.1) with and without 25 cm H2O/I/s added resistance (R). Reduction in slope of the ventilatory response to CO2 with R was highly significant in all 3 subjects whereas the response to hypoxia was barely significantly reduced in 1 subject and not significantly decreased in two. Although P0.1 was higher with than without R under all conditions, the slope of the P0.1 response to CO2 with R was not increased in two subjects and only slightly increased in the third. The slope of the P0.1 response to hypoxia was significantly greater in all subjects with R. Expiratory reserve volume was increased with R but the change was the same with hypoxia and hypercapnia. We conclude that ventilation is better maintained with resistive loading during hypoxia than during hypercapnia and that this results from a greater force output of inspiratory muscles as reflected by a higher P0.1. This suggests a greater neural output to these muscles.

Adult↗
PubMed1976

Hypoventilation in ponies after carotid body denervation.

Seven ponies were subjected to carotid body denervation (CD) and two ponies were sham operated (S). Measurement of arterial blood gases and arterial blood and cerebrospinal fluid (CSF) acid-base balance were made prior to and 1,2,4,9, and 17 wks after surgery in unanesthetized animals. Resting ventilation and ventilatory responsiveness to hypoxia and NaCN infusion were assessed prior to and 2,9, and 17 wks after surgery. Alveolar hypoventilation in the CD ponies was marked 1-2 wk after surgery when VE and VA were reduced 40% and 10%, respectively, from control and PaCO2 was 12-15 mmHg above control. However, the effect was not nearly as great 4, 9, and 17 wk after surgery when the PaCO2 stabilized at approximately 6 mmHg above control PaCO2. Arterial blood pH was normal in the hypercapnic CD ponies, but CSF pH remained acid relative to normal throughout the 17-wk period. Changes in ventilatory responsiveness to hypoxia and NaCN tended to parallel changes in resting ventilation. These findings suggest: 1) the carotid bodies are essential in ponies to maintain normal ventilation: 2) in CD ponies peripheral chemosensitivity is partially regained at some unestablished locus; and 3) pH compensating mechanisms in chronically hypercapnic ponies function relatively better in blood than in CSF.

Acid-Base Equilibrium↗
PubMed1976

Ventilatory control in peripheral chemoreceptor-denervated ponies during chronic hypoxemia.

The present study was designed to provide further insight into the role of the carotid and aortic chemoreceptors in ventilatory (VE) acclimatization during sojourn at altitude. Measurements were made: 1) on 10 ponies near sea level (SL, 740 Torr) under normal conditions, 2) on 6 of these at SL following chemoreceptor denervation (CD), and 3) subsequently on all 10 during 4 days of hypobaric hypoxia (PaO2 = 40-47 Torr). CD resulteo in hypoventilation at SL (deltaPaCO2 = d8 Torr, P less than 0.05), and it prevented hyperventilation normally observed with injection of NaCN and acute exposure to hypoxia (less than 1 h). In contrast, hyperventilation was evident in normal ponies during acute hypoxia (deltaPaCO2 = -6.7 Torr). Ventilation increased in both groups between the 2nd and 8th h of hypoxia (deltaPaCO2 from 1 h = -4 Torr, P less than 0.05). This change, a common characteristic of acclimatization, persisted throughout 4 days of hypoxia in the normal ponies. However, in the CD ponies this change was evident consistently only through the 12th h and after the 44 h hyperventilation was no longer evident. We conclude that the peripheral chemoreceptors are essential in ponies for normal VE acclimatization to this degree of hypoxemia. Two additional findings in CD ponies suggest the presence of a CNS inhibitory influence on the VE control center during chronic hypoxemia. First, acute hyperoxygenation on the 4th day of hypoxemia induced hyperventilation (deltaPaCO2 = -5 Torr, P less than 0.05). Second, again on the 4th day and during hyperoxygenation, VE responsiveness to CO2 and doxapram HCl was greater than at sea level.

Acclimatization↗
PubMed1976

Permselectivity of of the glomerular capillary wall. Studies of experimental glomerulonephritis in the rat using neutral dextran.

Polydisperse [3h] dextran was infused into eight Munich-Wistar rats in the early autologous phase of nephrotoxic serum nephritis (NSN), thereby permitting direct measurements of pressures and flows in surface glomeruli and fractional clearances for dextrans [(U/P) dextran/(U/P) inulin] ranging in radius from 18 to 42 A. Despite glomerular injury, evidenced morphologically and by a marked reduction in the glomerular capillary ultrafiltration coefficient, the glomerular filtration rate remained normal because of a compensating increase in the mean net ultrafiltration pressure. In NSN rats, as in normal controls, inulin was found to permeate the glomerular capillary wall without measurable restriction, and dextrans were shown to be neither secreted nor reabsorbed. For dextran radii of 18, 22, 26, 30, 34, 38, and 42 A, (U/P) dextran/(U/P) inulin in NSN and control rats, respectively, averaged 0.90 vs. 0.99, 0.81 vs. 0.97, 0.63 vs. 0.83, 0.38 vs 0.55, 0.20 vs. 0.30, 0.08 vs. 0.11, and 0.02 vs. 0.03. Using a theory based on macromolecular transport through pores, the results indicate that in NSN rats, effective pore radius is the same as in controls, approximately 50 A. In NSN, however, the ratio of total pore surface area to pore length, a measure of the number of pores, is reduced to approximately 1/3 that of control, probably due to a reduction in capillary surface area. These results suggest that proteinuria in glomerular disease is not due simply to increases in effective pore radius or number of pores, as previously believed. Using a second theoretical approach, based on the Kedem-Katchalsky flux equations, dextran permeability across glomerular capillaries was found to be slightly lower, and reflection coefficient slightly higher in NSN than in control rats.

Animals↗
PubMed1976

Permselectivity of the glomerular capillary wall. Studies of experimental glomerulonephritis in the rat using dextran sulfate.

To determine whether the increased filtration of serum proteins after glomerular injury is the consequence of altered electrostatic properties of the glomerular capillary wall, we measured fractional clearances of the anionic polymer, dextran sulfate, in nine Munich-Wistar rats in the early autologous phase of nephrotoxic serum nephritis (NSN). In agreement with previous studied from this laboratory, whole kidney and single nephron glomerular filtration rates were normal in NSN rats despite histological evidence of glomerular injury, and despite a marked reduction in the glomerular capillary ultrafiltration coefficient to approximately one-third of normal. In the companion study (9), it was shown that in NSN rats the mean fractional clearances of neutral dextrans over the range of effective molecular radii from 18 to 42 A were reduced, compared to normla. In contrast, in the present study the mean fractional clearances for dextran sulfate over the same range of molecular radii were significantly greater than those found previously for normal Munich-Wistar rats. The fractional clearance of dextran sulfate molecules of the same molecular radius as serum albumin (approximately 36 A) was increased markedly, from 0.015 +/- 0.005 (SEM) in nonnephritic controls to 0.24 +/- 0.03 in NSN (P less than 0.001). The sialoprotein content of glomeruli, estimated by the colloidal iron reaction, was reduced in NSN rats as compared to normal controls. It is concluded that the abnormal filtration of anionic serum proteins, such as albumin, seen in glomerulopathies is, at least in part, the consequence of loss of fixed negative charges from the glomerular capillary wall.

Animals↗
PubMed1975

Pulmonary ventilation, blood gases, and blood pH after training of the arms or the legs.

In two groups of young healthy subjects who performed arm training (N = 5) and leg training (N = 5), respectively, the respiratory adaptation to submaximal exercise with trained and nontrained muscle groups was compared by measurement of the ventilatory equivalent (Ve/Vo2, pH, and blood gases (Pco2, Po2, and So2) in arterial blood and in venous blood from exercising extremities. After training Ve/Vo2 was significantly reduced during exercise with trained muscles, but unchanged during exercise with nontrained muscles. The reduction in Ve/Vo2 was closely related to a less pronounced increase in heart rate and in arterial lactate content, but showed no quantitative correlation to changes in arterial adaptations in trained muscles are mainly responsible for the reduction in Ve/Vo2. After training during exercise with trained as well as nontrained muscles a shift to the right of the blood oxygen dissociation curve occurred as extremities was lower while corresponding Po2 was higher.

Adult↗
PubMed1975

Computerized method for analyzing maximum and partial expiratory flow-volume curves.

Computerized instrumentation and software have been developed to obtain maximum expiratory flow-volume (MEFV) and partial expiratory flow-volume (PEFV) curves. The computerized system calculates and prints out the flow at 25% and 40% of control vital capacity (VC), the expiratory volume, peak expiratory flow rate and expiratory volume at one second (FEV1) divided by VC, the latter expressed as a percent. The flow-volume curves can be displayed on an oscilloscope or plotter and stored on magnetic tape. A pilot study was completed to demonstrate the reliability and validity of the data obtained.

Computers↗
PubMed1975

Social interaction, social competence, and friendship in children.

The relationship between social skills, social interaction, and popularity was examined. The subjects were 198 children in third and fourth grades in middle- and low-income schools. The relationships between number of friends, socioeconomic status, and grade level were studied in a 2 times 2 times 2 factorial design with 2 sets of dependent measures: (1) social skills were assessed by an experimenter testing each child individually on a set of tasks which included measures of the ability to label emotions in facial expressions, knowledge of how to make friends, giving help, and role-taking ability; and (2) social interaction in the classroom was assessed using a naturalistic observational system. Popular and unpopular children differed in their knowledge of how to make friends and on the referential-communication task. In the classroom, popular children distributed and received more positive reinforcement than unpopular children and spent less time daydreaming. Both grade and social class factors were significant. However, different patterns of results contributed to the main effect of friends and the grade-level main effect. The importance of assessing social skills which are first validated by reference to a criterion such as sociometric position was noted.

Age Factors↗