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Biomedical subjects

B Husum

Publications and source records attributed to B Husum.

At least 37 records · Page 2Linked to original sources
PubMed1986

Very low sister-chromatid exchange rate in Seventh-Day Adventists.

42 Seventh-Day Adventists (SDAs) and 42 controls matched for sex, age and occupation had their sister-chromatid exchange (SCE) examined in peripheral blood lymphocytes. This was done to examine if the SCE frequency was lower in this group of people, who are known to have a decreased cancer risk compared to the general population. The average SCE/cell in 30 cells from each person was 5.54 +/- 0.07 (mean +/- standard error of the mean) for the SDAs and 8.00 +/- 0.15 for the controls, the difference being statistically significant (p less than 0.00001). No difference in SCE frequency was found between SDAs eating only an ovo-lacto-vegetarian diet and those eating some fish or meat. The mitotic index (MI) was significantly higher and the replication index (RI) was significantly lower in SDAs than in controls. No correlation was found between gamma (a statistical transformation of SCEs/cell) and MI or RI within the groups of SDAs or controls. In the pooled data there was a negative correlation of gamma and MI and a positive correlation of gamma and RI. Of the interpersonal variation in gamma 8% and 14% could be explained by MI and RI. The finding of a lower SCE frequency in a group of SDAs who have a low risk of cancer might indirectly indicate a relation between SCE and cancer and encourages further studies of SCE and diet.

Adolescent↗
PubMed1986

Dissociation of renal and respiratory effects of acetazolamide in the critically ill.

The effects of acetazolamide on renal and erythrocyte carbonic anhydrase were studied in 12 critically ill patients. In the first part of the investigation (n = 6) we examined the renal effects of increasing doses of acetazolamide. The maximal renal excretion of water and bicarbonate was achieved with acetazolamide 2.5-5 mg kg-1 i.v. In the second part (n = 6), the associated respiratory effects of the effective renal dose of acetazolamide 5 mg kg-1 were evaluated. We found a statistically significant 4% decrease in pulmonary carbon dioxide excretion in the 10-min sampling period immediately following the administration of acetazolamide, but thereafter carbon dioxide elimination proceeded at a normal rate. The observed carbon dioxide retention is clinically unimportant, and we recommend acetazolamide as an effective means of eliminating surplus water and bicarbonate in the critically ill.

Acetazolamide↗
PubMed1986

Perivascular axillary block VII: the effect of a supplementary dose of 20 ml mepivacaine 1% with adrenaline to patients with incomplete sensory blockade.

Perivascular axillary blockade was performed on 233 patients with the aid of a catheter technique. All patients received a primary injection of 50 ml of mepivacaine 1% with adrenaline. Sensory blockade was evaluated 20, 30 and 40 min after injection, and a complete sensory blockade was found in 90 (39%), 131 (57%) and 146 (63%), respectively. The blockade effect of a supplementary perivascular injection of 20 ml of the same agent was investigated on the remaining 87 blockades, which could be divided into three categories: blockades which at 20 min showed lack of analgesia in several cutaneous segments of the hand (34 patients); blockades which at 30 min showed a total lack of sensory blockade within a limited area (29 patients); and blockades which at 40 min showed signs of blockade of all cutaneous segments, but one or several segments were not blocked with an intensity compatible with surgery (24 patients). Blockades of categories 1 and 2 were at 20 and 30 min, respectively, randomly allocated to control or to perivascular supplementation groups, while blockades of category 3 all had supplementation at 40 min. Sensory blockade was reevaluated 10 and 20 min after group allocation, and it was found that perivascular supplementation had no significant effect on the sensory blockade in category 1 and 2, while 68% of the blockades in category 3 improved to a complete blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

PEEP reverses nitroglycerin-induced hypoxemia following coronary artery bypass surgery.

Intravenous nitroglycerin is increasingly used during and after cardiac surgery to control blood pressure and improve subendocardial and peripheral circulation. A dramatic decrease in arterial oxygenation has, however, been reported in a number of poorly controlled clinical trials. In the present investigation 16 patients were studied 2-4 h after coronary artery bypass procedures. All were treated with a continuous infusion of nitroglycerin (1 microgram X kg-1 X min-1). Utilizing an on-off-on drug design, it was clearly established that nitroglycerin depresses arterial oxygenation by increasing the pulmonary venous admixture. Three possible underlying mechanisms are discussed, but at the present time no firm conclusion can be drawn as to the nature of the changes. Eight patients were ventilated with 1 kPa (10 cmH2O) positive end-expiratory pressure (PEEP) during the nitroglycerin infusion. PEEP-ventilation reversed nitroglycerin-induced changes in arterial oxygenation and pulmonary shunting without adversely affecting hemodynamic stability.

Coronary Artery Bypass↗
PubMed1986

Sister chromatid exchanges in lymphocytes of dentists and chairside assistants: no indication of a mutagenic effect of exposure to waste nitrous oxide.

Cytogenetic methods are used increasingly for monitoring occupational exposure to potential mutagenic agents. By one such method, the sister chromatid exchange (SCE) test, previous studies of hospital operating room personnel did not indicate any mutagenic effect from exposure to waste anesthetic gases. Dentists and their assistants are exposed to much higher levels of nitrous oxide than hospital personnel, and in studies of dentists it is possible to eliminate bias from concomitant exposure to halogenated anesthetics by including unexposed persons engaged in the same professional activities as the exposed persons. SCE was examined in lymphocytes of venous blood from 38 female dentists and 74 chairside assistants, all working in the Child Dental Service, and 30 male dentists, of whom 23 worked in private practice. From studies of the model y = bo + b1 X age + b2 X cig./day + b3 X hours of exposure to nitrous oxide/week, by multiple linear regression, there was no indication of any influence of exposure to nitrous oxide on SCE. It was concluded that, from the SCE test, there is no indication of a mutagenic effect from exposure to waste nitrous oxide, and that possible health hazards from such exposure would be induced by other effects of nitrous oxide.

Adolescent↗
PubMed1986

Brain oedema and blood-brain barrier permeability in pulsatile and nonpulsatile cardiopulmonary bypass.

In pigs subjected to pulsatile or nonpulsatile cardiopulmonary bypass (CPB) at normothermia for 3 hours, evaluation was made of water content in brain tissue (specific gravity measurements), blood-brain permeability to serum proteins (immunocytochemical demonstration of extravasated proteins, using peroxidase-antiperoxidase technique) and histopathology (paraffin sections). The specific gravity in parietal cortex was higher after pulsatile than after nonpulsatile CPB or in control pigs, the change corresponding to a 6.3% water increase. The tissue water content was unchanged in the internal capsule, basal ganglia and nucleus accumbens after CPB. The vascular permeability to serum proteins was unchanged after nonpulsatile CPB, but after pulsatile CPB minute foci of extravasated serum proteins appeared. All the animals showed dark neurons in cortical and subcortical regions, but these could have been artefacts in immersion-fixed tissue. There were no other signs of ischaemic tissue damage. The study indicated that cortical oedema may follow pulsatile CPB, the cause being altered permeability of the blood-brain barrier to serum proteins.

Animals↗
PubMed1985

Oxygen uptake and carbon dioxide elimination after acetazolamide in the critically ill.

Acetazolamide, which reversibly inhibits carbonic anhydrase, is a useful diuretic in alkalotic and over-hydrated patients. In two earlier investigations we have consistently found increases in the arterial and venous oxygen saturation and tension when patients were treated with acetazolamide 15 mg . kg-1. A plausible explanation of this phenomenon is that acetazolamide diminishes oxygen consumption. In the present study we measured oxygen uptake in 10 critically ill patients. We found a minor and statistically insignificant decrease in oxygen consumption. Nevertheless SVO2 increased from 0.77 to 0.83 and PVO2 from 5.9 kPa to 6.8 kPa. It is still not possible from this investigation to determine the origin of the improvement in blood oxygenation. The inhibition of carbonic anhydrase caused a CO2 retention of 5.8% of the total CO2 production. An increase in body stores of CO2 of this magnitude is without clinical significance.

Acetazolamide↗
PubMed1985

Sister chromatid exchanges in cigarette smokers: effects of halothane, isoflurane or subarachnoid blockade.

In a previous study of the potential mutagenic action of isoflurane using the sister chromatid exchange (SCE) test in lymphocytes of surgical patients, it appeared that SCE increased in a group of 11 cigarette smokers, there being no effect in patients who were non-smokers. In the present study, 63 cigarette smokers were examined by the SCE test before and after minor orthopaedic operations undertaken under halothane or isoflurane anaesthesia, or subarachnoid analgesia. No significant changes of SCE were observed, and the risk of having missed a "true" increase of more than 0.6 SCE per cell was less than 1%. It was concluded that, in cigarette smokers, SCE in lymphocytes were unchanged after both general anaesthesia and subarachnoid analgesia, and that there was no indication from the SCE test of a mutagenic action of halothane, or isofurane, in nitrous oxide.

Adolescent↗
PubMed1985

Monitoring of sister chromatid exchanges in lymphocytes of nurse-anesthetists.

Cytogenetic methods are used increasingly for monitoring exposure to potential mutagens/carcinogens in the environment. By one such method, the sister chromatid exchange (SCE) test, comparison of different groups of hospital personnel has not indicated any mutagenic effect of occupational exposure to waste anesthetic gases. Since no information is available on repeated examinations of operating room personnel during a longer period of occupational exposure, the authors examined SCE in lymphocytes in a total number of 191 venous blood samples drawn from 14 previously unexposed nurses before and during up to 32 months of training as nurse-anesthetists. The initial SCE/cell ranged from 8.03 to 13.13 SCE/cell. Individual linear regressions were performed for the transformed variable, y = (sum SCE)1/2 + (sum SCE + 1)1/2, on time; and for the first 6-month period, the weighted mean of individual slopes was b0 = -0.119 +/- 0.088, not significantly different from zero. Calculated for the whole observation period, b0 = 0.030 +/- 0.014, P = 0.034 (two-tailed t test). Converted into SCE/cell, SCE would decrease 0.10 SCE/cell for each 6-month period of exposure (95% confidence limits 0.07-0.13 SCE/cell). The reason for this apparent decrease remains unknown. The results of the present study were in accord with previous studies of operating room personnel and of patients anesthetized with inhaled anesthetics. It was concluded that there is no indication, from the SCE test, of a mutagenic action due to exposure in vivo to currently used inhalation anesthetics.

Adult↗
PubMed1985

Pulsatile flow during cardiopulmonary bypass. Evaluation of a new pulsatile pump.

Pulsatile cardiopulmonary bypass (CPB) has been suggested to be superior to nonpulsatile CPB. This report concerns a newly developed pulsatile pump for clinical use. It is designed as a positive displacement pump, with blood allowed to collect in a valved cavity from which it is ejected by the reciprocating action of a piston. Using a uniform procedure of anaesthesia and surgery, 14 pigs were subjected to CPB at 37 degrees C for 3 hours. The pulsatile pump was used in seven pigs and a conventional roller pump in the other seven. The wave-form of the pulse during pulsatile CPB was similar to that recorded in the pigs before bypass. The values for rate of pressure change with respect to time (dp/dt) obtained in the aorta were close to the pre-CPB values. No difference was found between the two groups with respect to platelet count or haemolysis. The investigated pulsatile device appeared to be reliable and easy to handle, and the pulsation it produced closely resembled the physiologic pulse-wave form.

Animals↗
PubMed1985

Nonpulsatile cardiopulmonary bypass disrupts the flow-metabolism couple in the brain.

The effect of cardiopulmonary bypass on the relationship between brain glucose consumption and regional blood flow is unknown. We measured this relationship in pigs subjected to 3 hours of pulsatile or nonpulsatile cardiopulmonary bypass at normothermia and compared the results to the relationship established in a control group of pigs. A total of 10 regions were sampled in both hemispheres of the porcine brain. In control pigs, cerebral blood flow averaged 46 ml/100 gm and the glucose consumption, 21 mumol/100 gm/min. The ratio between blood flow and glucose consumption was close to 2 ml/mumol in all regions. In pulsatile cardiopulmonary bypass both the whole-brain average and the regional values declined, so that the ratio remained the same, about 2 ml/mumol. In nonpulsatile cardiopulmonary bypass regional blood flow remained normal; the average was 49 ml/100 gm/min, whereas the average glucose consumption declined to 16 mumol/100 gm. In regions with high blood flow rates, the ratio between blood flow and glucose consumption increased to about 3 ml/mumol, indicating perfusion in excess of metabolic demand. We conclude that nonpulsatile cardiopulmonary bypass at normothermia affects the metabolic flow regulation in the brain by interfering with the myogenic contractility of cerebral arterioles.

Blood Flow Velocity↗
PubMed1985

ATP-content in muscular interstitial fluid during pulsatile and non-pulsatile cardiopulmonary bypass in pigs.

The potential benefit of pulsatile flow during cardiopulmonary bypass (CPB) has been discussed extensively, but the debate is still unsettled. Release of intracellular ATP is a useful indicator of cellular damage; we have measured the ATP content in perfusates from muscles in pigs undergoing pulsatile or non-pulsatile CPB for 100 min at 37 degrees C. In 5 pigs the Polystan Pulsatile Pump was used and in 5 pigs a conventional roller pump. 11 pigs served as controls; 6 received heparin like the animals subjected to CPB, whereas the remaining 5 animals were not heparinized. ATP was measured by the firefly luminescence technique. At the start of the CPB or control period the ATP content was very low in all 4 groups. In the non-heparinized controls ATP continued to decrease, whereas in the other 3 groups ATP increased linearly during the 100 min of CPB or control period. It is concluded that, by this method, there was no significant difference between pulsatile and non-pulsatile CPB regarding damage to vascular endothelial or smooth muscle cells. However, heparinization per se caused a marked leakage of blood cells into the extravascular space even after the initial leakage from the cannulation had disappeared. This leakage was enhanced by non-pulsatile but not by pulsatile CPB.

Adenosine Triphosphate↗
PubMed1984

Guidelines for the statistical evaluation of SCE.

When planning studies by the sister chromatid exchange (SCE) test, it is necessary to calculate the size of the test groups, taking into consideration the variance of the test result and the statistical distribution of SCE frequencies. This paper deals with these problems. Recommendations are given for the preparation of slides under standardized conditions, for the subsequent counting of SCEs/cell in a random sample of 30 cells from each slide, and for the condensation of the information contained in the sample of 30 counts into a single statistic, that may be treated as a normally distributed variable. The adequacy of this transformation is shown for the data from 170 different subjects. Of these, 165 (58 nonsmokers and 107 cigarette smokers) had mean values of SCE/cell ranging from 6.5 to 13.5, while the remaining 5 subjects were on intermittent treatment with cytostatics every fourth wk, and exhibited a mean value of SCE/cell in the range 15-23. The variance associated with the recommended statistic has been decomposed into 4 variance components: variance within slides, variance between slides prepared from the same blood sample, variance within subjects, and variance between subjects. Based on a total of 680 SCE analyses in 218 persons, estimates of these variance components are given and used to calculate the necessary number of samples for the detection of a prescribed difference in SCEs/cell for selected values of Type I and Type II errors.

Analysis of Variance↗
PubMed1984

Distribution of SCEs in lymphocytes in persons with normal, slightly increased, and heavily increased SCEs.

The distribution of SCEs in lymphocytes was examined for 165 healthy persons (58 non-smokers and 107 smokers with cigarette consumption ranging from 1 to greater than 20 per day), and for 1 patient treated with melphalan, a cytostatic drug. The data from the healthy persons did not follow a Poisson distribution. A mixed Poisson that allowed different lambda values for the 30 cells scored from each person and postulated a gamma distribution for the lambda s within the 30 cells fitted all the data examined including those from the melphalan-treated patient. In the latter case the 7 samples taken at various times after the treatment could all be represented satisfactorily with a common parameter, c, in the gamma distribution for the lambda s, even though the mean SCEs/cell varied from 9.8 to 36.8. Because the c parameter determines the spread of lambda values within the 30 cells, this suggested that the effect of the cytostatic drug was to increase all the lambda s by a constant amount. The sum of the SCEs taken over all 30 cells in a sample is a convenient summary statistic, and the transformation y = square root s + square root s + 1 behaves as a normal variate with a constant variance within a group.

Adolescent↗
PubMed1984

Sister chromatid exchanges in lymphocytes of humans anaesthetized with isoflurane.

The potential mutagenicity of isoflurane was investigated by the sister chromatid exchange (SCE) test using peripheral blood lymphocytes from patients before and after anaesthesia. Thirty patients, aged 18-59 yr (median 29.5 yr), were anaesthetized for minor orthopaedic operations with isoflurane and nitrous oxide in oxygen for 37-90 min (median 64 min). Venous blood samples were drawn before the induction of anaesthesia, immediately after completion of anaesthesia and on the following day. SCE was examined in 30 cells from each specimen. In the 30 patients, the SCE values observed immediately after completion of anaesthesia and the day after were not different statistically from the SCE values observed before the induction of anaesthesia. Separate statistical evaluation of SCE observed among the 19 non-smoking patients also revealed unchanged SCE values. In 11 cigarette-smoking patients (average 10 cigarettes per day), SCE was increased the day after operation when compared with SCE before the induction of anaesthesia (P less than 0.02). This might reflect differences in SCE formation attributable to the patients' smoking habits, but further studies of SCE in cigarette smokers are required to elucidate this. It was concluded that there was no indication, from the SCE test, of a mutagenic effect of short-term exposure to anaesthetic concentrations of isoflurane and nitrous oxide in oxygen.

Adolescent↗