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Biomedical subjects

R Kummer

Publications and source records attributed to R Kummer.

8 recordsLinked to original sources
PubMed1999

Thermodiffusion for continuous quantification of hepatic microcirculation--validation and potential in liver transplantation.

Hepatic microcirculation is a main determinant of reperfusion injury and graft quality in liver transplantation. Methods available for the quantification of hepatic microcirculation are indirect, are invasive, or preclude postoperative application. The aim of this study was the validation of thermodiffusion in a new modification allowing long-term use in the clinical setting. In six pigs Doppler flowmeters were positioned around the hepatic artery and portal vein for the measurement of total liver blood flow. Liver perfusion was quantified by thermodiffusion and compared to H(2) clearance as an established technique under baseline conditions, during different degrees of portal venous obstruction and during occlusion of the hepatic artery. Thermodiffusion measurements were recorded for five days postoperatively followed by histological evaluation of the hepatic puncture site. Perfusion data obtained by thermodiffusion were significantly correlated to H(2) clearance (r = 0.94, P < 0. 001) and to liver blood flow (r = 0.9, P < 0.05). The agreement between thermodiffusion and H(2) clearance was excellent (mean difference -2.1 ml/100 g/min; limits of agreement -12.5 and 8.3 ml/100 g/min). Occlusion of the portal vein or hepatic artery was immediately detected by thermodiffusion, indicating a decrease of perfusion by 64 +/- 7% or 27 +/- 5% of baseline, respectively. Perfusion values at baseline and during vascular occlusion were reproducible during the entire observation period. Histological changes of the liver tissue adjacent to the thermodiffusion probes were minute and did not influence long-term measurements. In vivo validation proved that enhanced thermodiffusion is a minimally invasive technique for the continuous, real-time quantification of hepatic microcirculation. Changes in liver perfusion can be safely detected over several days postoperatively. The implication for liver transplantation has led to the clinical application of thermodiffusion.

Animals↗
PubMed1997

[Heart rate, blood lactate concentration and subjective stress perception in submaximal running: new nomograms for assessment of endurance capacity].

Considering the protective effect of physical activity against coronary heart disease, the estimation of endurance capacity is not only recommended for sportsmen but is also useful for exercise counselling of unfit persons. Endurance capacity can be estimated with test protocols leading to complete exhaustion, or by submaximal test procedures. Submaximal tests have the advantage of putting less stress on subjects than maximal test protocols; on the other hand, they are less accurate. As a complement to traditional submaximal test protocols based on heart rate analysis, a new submaximal protocol is proposed based on measurements of capillary blood lactate concentration during exercise. Incremental tests of 319 men with wide variation of endurance capacity were used to calculate nomograms of the typical pattern of exercise-induced increase in capillary blood lactate concentration, heart rate, and rating of perceived exertion in relation to endurance capacity. The running velocity eliciting a capillary blood concentration of 4 mmol/l lactate was selected as the parameter for endurance capacity. With the help of these nomograms, the 4 mmol/l-velocity could be estimated with submaximal values of lactate, heart rate or rating of perceived exertion. The appropriateness of the nomograms was checked against the data of 100 independent maximal treadmill tests. Estimation of 4 mmol/l-velocity with submaximal lactate values showed good precision (with a small standard deviation of +/-0.17 m/s); in contrast, the estimation of endurance capacity with submaximal values for heart rate and rating of perceived exertion showed substantially larger standard deviations (approximately +/-0.56 m/s). We conclude that, for estimation of endurance capacity from submaximal running values, the nomogram for blood lactate concentrations can be recommended.

Adolescent↗
PubMed1993

Selenium status of infants is influenced by supplementation of formula or maternal diets.

Plasma selenium of infants fed proprietary formula was significantly less than that in infants fed human milk. Addition of selenite to the formula (0.253 mumol Se/L) increased plasma selenium and activities of glutathione peroxidase (GPx) and total peroxidase (Px). However, erythrocyte selenium decreased significantly during the 12-wk study in infants receiving human milk or formula with or without supplemental selenite. Infants fed human milk from women receiving 0 or 200 micrograms supplemental selenium as selenomethionine or selenium-enriched yeast had plasma selenium that paralleled changes in their selenium intake. Plasma GPx and Px activities were unrelated to human milk selenium intake. Milk from women given either selenium supplement prevented the decline in infant erythrocyte selenium. Results of these studies suggest that the method of feeding modifies the infant's apparent selenium status and that the molecular form of selenium provided and/or its interaction with other milk constituents are determinants of infant selenium status.

Anthropometry↗
PubMed1993

Selenium status of lactating women is affected by the form of selenium consumed.

The impact of providing selenomethionine (2.7 mumol Se) or selenium-enriched yeast (2.9 mumol Se) on the selenium status of lactating and nonlactating women with customary intakes of approximately 1.3 mumol Se/d was studied. Plasma selenium declined in unsupplemented lactating women but not in nonlactating women. Selenomethionine increased plasma selenium in both lactating and nonlactating women whereas selenium-enriched yeast increased plasma selenium only in nonlactating women. Erythrocyte selenium concentration was not significantly modified by lactation. Plasma glutathione peroxidase (GPx) activity decreased with duration of lactation in unsupplemented women and selenomethionine or selenium-enriched yeast supplementation prevented the decline. Milk selenium declined markedly for 20 wk after parturition in unsupplemented women. Selenomethionine significantly increased milk selenium concentrations whereas selenium-enriched yeast prevented a decline. These results clearly show that the source of selenium provided to lactating women can significantly influence selected indexes of selenium status, including milk selenium concentration.

Adolescent↗
PubMed1986

Field studies on health effects from the application of two organophosphorus insecticide formulations by hand-held ULV to cotton.

Two field studies to assess the health implications for farmers applying two different formulations containing organophosphorus (OP) pesticides to cotton by hand-held ULV are described. The first study, carried out in the Ivory Coast, involved the application of an endrin/DDT/methylparathion (MEP) formulation in an aromatic hydrocarbon solvent. The second study took place in Indonesia with a 20% monocrotophos formulation in a mixture of a glycol and a glycol ether. Both studies were carried out under actual field conditions. The purpose of the studies was to get a good assessment of the health hazards of the particular formulation, used under the specific circumstances and agronomic requirements of the area of application and taking into account all local, climatic and cultural conditions that could be of possible influence. The results showed that in both studies skin exposures took place during application and especially during handling, filling and cleaning, and that inhalation of spray mist was negligible. Absorption was confirmed by the presence in urine of metabolites of endrin and methylparathion in the Ivory Coast study, and of dimethyl phosphate in the Indonesia study. No clinical signs or symptoms of intoxication were discovered in either study, nor were inhibitions of cholinesterase (ChE) activity of health significance established under the conditions of the studies. In addition, various practical aspects such as choice of apparatus, of formulation, the application procedures etc. are discussed.

Agriculture↗
PubMed1980

Association between mammographic parenchymal pattern classification and incidence of breast cancer.

Wolfe has suggested that the mammographic parenchymal patterns can be used to identify a group with high incidence of breast cancer. To evaluate this claim, mammograms of women with breast cancer that was detected at the University of Michigan Breast Cancer Detection Demonstration Project have been classified and compared with a randomly selected control group from the same project. The basic mammographic classifications as defined by Wolfe were used with further refinements made in the DY and QDY groups. The mammographic classifications have been grouped according to the degree of density and age. For all ages combined, our dense classifications (DY1, DY2, DYC-, QDY2) show a higher incident rate, 22/1000,than the lucent classification (N1, P1, and QDY1),9/1000,(P less than .01), although not to the degree suggested by Wolfe. This difference is statistically significant (P less than .01); the higher risk is markedly increased for women under 50 years of age (P less than .005). After age 50 the higher risk associated with the dense breast seems to disappear (P less than .13). However, this might be a consequence of women who were in a dense classification at an earlier age who subsequently changed to a lucent classification later in life. Because the percentage of lucent breasts increases with age there is a higher absolute number of cancers (55%) in this group of women past 50; these women cannot be neglected in screening. Our results suggest the following guidelines for clinical evaluation: (1) Careful mammographic and clinical follow-up for any woman with a dense breast at any age. (2) Careful mammographic and clinical follow-up past 50 regardless of breast classification. (3) Women with lucent breasts under age 50 represent a low risk category and may not require as frequent a follow-up as the other mammographic types.

Adult↗