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Biomedical subjects

H C Wulf

Publications and source records attributed to H C Wulf.

At least 163 records · Page 9Linked to original sources
PubMed1986

Relative ultraviolet spectral intensity of direct solar radiation, sky radiation and surface reflections. Relative contribution of natural sources to the outdoor UV irradiation of man.

Relative measurements of UVA and UVB radiation from the sun and the sky, as well as the reflected intensity from various land and water surfaces, have been carried out in the Copenhagen area. The measurements were taken in January and in the period April through July and supplemented by measurements in Greenland during May. Likewise, the angular distribution of direct solar radiation and sky radiation close to the direction of the sun was measured with a 0.5 degree field of view. Absolute UV irradiances were measured with detector-filter combinations. Calculations of the relative contributions of direct solar radiation, sky radiation and reflected radiation to the irradiation of a standing person show, in particular, that if seawater with waves is the surrounding scene, its reflected radiation will account for more than 10% of the received UV dose.

Denmark↗
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

Different sister chromatid exchange rates in XX and XY cells of a pair of human chimeric twins.

To explore the influence of sex on sister chromatid exchange (SCE) level, a pair of chimeric twins was examined for differences in SCE frequency between the XX and XY cells present in each individual. By this method, the influence of possible differences in environmental exposure was eliminated. SCE levels were varied by growing the cells in media containing 0, 1.3 X 10(-7), or 6.5 X 10(-7) M melphalan. XX cells showed a higher SCE count than XY cells. This difference increased with increasing SCE level and ranged from 5.4% to 7.8% (P = 0.0003) of the SCE counts. Only about 2% of the difference could be explained by the higher amount of DNA present in the XX cells than in the XY cells. In this case XX cells seemed to be more sensitive to SCE-inducing agents than XY cells.

Cells, Cultured↗
PubMed1985

Cadmium concentrations in blood samples from an East Greenlandic population.

An analysis for cadmium was made of 101 human blood samples from the district of Angmagssalik, East Greenland, and 29 from East Greenlanders living temporarily in Copenhagen. No relationship could be found between concentrations of blood cadmium and ethnic origin (Eskimos--Danes), sex, age or amount of seal eaten. Only smoking habits were reflected, as a median of 2.2 micrograms/l was found in smokers and 1.1 in non-smokers. Since analyses of organs from seals have suggested that the WHO provisional, tolerable weekly intake is exceeded by a factor as high as 10 as a result of seal eating, it is surprising that seal eating is without any effect on the blood concentration.

Animals↗
PubMed1985

Choosing the proper filter/detector combination for the measurement of UVA and UVB radiation from various light sources.

UVA and UVB radiation is often measured with simple detectors by non-skilled personnel. In this study spectroradiometric measurements are compared to measurements with simple detectors equipped with various filters or filtercombinations. Measurements have been performed on light sources commonly used in dermatology such as UVA and UVB fluorescent tubes and medium pressure Mercury lamps, as well as on a Quartz Halogen lamp. Our results show that the application of Si photodiodes should, generally, be avoided, that UVA measurements can be performed with reasonable accuracy with detectors which are not sensitive to near infrared radiation when combined with simple filters, and that UVB measurements should be made with solar blind detector types for best all-round results.

Evaluation Studies as Topic↗
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

An unusual case of multiple malignancy in an adult.

An adult female is described who, during a clinical course of 25 years, presented malignant tumors of the rectum, breast, uterus and colon. Cytostatics were never administered. Lymphocyte subsets, a variety of lymphocyte and mononuclear cell stimulation assays with mitogens and antigens, DNA repair tests and activity of natural killer cells were normal. Serum leukocytic interleukin-1 activity was slightly elevated. Sister chromatid exchange frequency in peripheral lymphocytes was below the normal range. An explanation for the development of 4 primary malignant neoplasms was not found.

Breast Neoplasms↗
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

Selenium and its interrelation with mercury in wholeblood and hair in an East Greenlandic population.

138 Blood samples and 12 hair samples from the district of Angmagssalik, East Greenland, have been analysed for selenium and mercury. It was found that selenium like mercury, was absorbed in accordance with the amount of marine food eaten. The mean blood concentration in the group eating most marine food was 173 and 186 micrograms Hg/1 for men and women, respectively, while in the group eating the lowest quantity of marine food, the mean values were 86 and 118 micrograms Hg/1. In blood, the selenium and mercury did not correlate in individuals, but only in groups according to eating habits. On a molar basis, selenium is present in blood in excess as compared to mercury, while the opposite is the case for hair. It is concluded that only part of the selenium interacts with mercury, and that blood, but not hair, reflects present dietary intake. The righ supply of selenium in relation to mercury exposure through the traditional arctic food is probably able to alleviate the hazards from dietary mercury exposure.

Adult↗
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↗
PubMed1984

Sister chromatid exchange in patients treated with methotrexate for psoriasis.

Sister chromatid exchange (SCE), which is considered a sensitive method in evaluation of mutagenicity and may be an indicator of carcinogenicity, was determined in lymphocytes from 8 patients with severe psoriasis who underwent treatment with oral methotrexate (MTX). During the treatment period (median 118 days, range 50-298 days) a significant increase in SCE compared to the pretreatment value was found in 1 patient only. It is concluded that no long-term damage as measured by SCE occurs in lymphocytes from psoriasis patients treated with MTX.

Adult↗