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Biomedical subjects

M Hubmann

Publications and source records attributed to M Hubmann.

At least 19 recordsLinked to original sources
PubMed2002

Cardiovascular function of workers exposed to carbon disulphide.

OBJECTIVES: The aim of the study was to verify that exposure to carbon disulphide (CS(2)) up to 10 ppm results in a negative inotropic effect on cardiovascular function. METHODS: In a cross-sectional study a total of 325 workers exposed to CS(2) in the rayon-producing industry and 179 controls from the same plants were examined. The exposure assessment was based on personal air sampling and biological monitoring (2-thiothiazolidine-4-carboxylic acid (TTCA) in urine) for all persons. The examination consisted of a standardised questionnaire, physical examination, assessment of body fat mass, ergometric test with the determination of work capacity at heart rates of 100, 130, 150 and 170 beats/min, and electrocardiography. RESULTS: The mean external exposure was 6.04 ppm CS(2) (range: 0.03-91.08); the mean internal exposure was 1.14 mg TTCA/g creatinine (range: 0.02-11.50). The workers exposed to CS(2) showed better physical fitness. The diameters of the left heart chamber of the exposed persons were not significantly different when compared with occupationally non-exposed workers, but there was a tendency of increasing diameters for the exposed employees. In the multiple linear regression the diameters showed physiologically plausible correlations with the body mass index, body fat mass, alcohol consumption, and physical fitness, but not, however, with the exposure, neither with the exposure group in all persons nor with the internal or external exposure within the exposed workers. CONCLUSIONS: In this study, differences in the heart chamber diameters between exposed persons and controls could not be confirmed. Differences in physical fitness and constitution can explain differences in heart chamber diameters.

Adult↗
PubMed2001

Lack of association between childhood stroke after varicella and human leukocyte antigen (HLA)-B51.

Human leukocyte antigen (HLA)-B51 has been suggested as an immunogenetic marker for a genetic predisposition to vascular occlusion in response to an immunological stimulus. Varicella has been reported to be a possible risk factor for stroke. We performed DNA-based HLA typing in 11 young patients (mean age: 5.2 years) with unexplained ischaemic stroke. In eight of them varicella had occurred before their stroke. HLA-B51 was negative in all 11 patients and we did not find any significant accumulation of other HLA-subgroups. Our study does not support an association between susceptibility to stroke after varicella and HLA-B51.

Chickenpox↗
PubMed2001

[Practical usage of a quality management system according to ISO 9001 : 2000 focusing on the double contrast (barium) enema].

PURPOSE: We describe the implementation of quality improvement measures in a quality management system. METHODS: With questionnaires for radiologists and patients, we investigated the relations between patient preparation and diagnostic quality serving the main purpose, to improve diagnostic quality with the help of more detailed patient information (e.g., changing preparation sheets and handling out "peri-med" information sheets to the patients). Furthermore, a comparative data ascertainment at other institutes was integrated. RESULTS: For the group of outpatients, increasing process quality (patient information) and outcome (diagnostic quality) could be achieved. Taking aspects of quality costs into consideration, a decrease in costs due to failures was achieved. CONCLUSION: More detailed patient information has positive effects on diagnostic quality of the double contrast (barium) enema.

Attitude of Health Personnel↗
PubMed1997

Comparison between three transmucosal routes of administration of midazolam in children.

Midazolam was applied transmucosally in 47 children randomly assigned to three different groups. Group N received 0.2 mg.kg-1 nasally, group R 0.5 mg.kg-1 rectally, and group S 0.2 mg.kg-1 sublingually. All groups were treated 60 min prior to a planned i.v. puncture with EMLA. Reliable and valid psychological parameters (such as emotional situation, shivering, awareness, respiratory rate and facial colour) were scored after premedication and before and after i.v. puncture, 20 min after premedication and until induction. A blood sample was drawn 10, 30 and 60 min after premedication and the levels of midazolam, alpha-hydroxy-midazolam, ACTH, glucose and cortisol were measured. In all three groups the plasma levels of midazolam 10 min after premedication were higher than 70 ng.ml-1 (accepted as a sedative level). 30 min after premedication the midazolam level in the sublingual group was statistically significantly higher than in the nasal group and the psychological parameters in all three groups were significantly changed (10 min after premedication). The psychological parameters were not significantly different between the three groups over the whole study. Sublingual premedication has some advantages (most readily accepted, highest plasma levels and lowest deviations) and could be the first choice in premedication of children. All three transmucosal applications are safe and well accepted, although nasal application was rejected by two of the children.

Administration, Intranasal↗
PubMed1996

Carbon disulphide. IV. Cardiovascular function in workers in the viscose industry.

OBJECTIVE: The aim of the study was to examine whether an increase can be detected in the prevalence of coronary heart disease or a higher prevalence of unusual cardiological findings in workers with occupational exposure to carbon disulphide (CS2) at the level of the threshold limit value of 10 ppm currently valid in occupational medicine. METHODS: In a cross-sectional study we investigated 247 men occupationally exposed to CS2 and a comparable control group (n = 222). The current exposure to CS2 was measured using personal air monitoring and biological monitoring of all test persons. A cumulative exposure index (median of CS2 exposure in the past multiplied by the duration of employment) was calculated. In addition to collecting comprehensive anamnestic data on all persons, we carried out a physical examination, an ultrasound examination of the large arteries, a resting and exercise ECG and an echocardiographic examination. RESULTS: No increase could be found in the prevalence of coronary heart disease or of arteriosclerotic findings in the exposed subjects. There was no difference in the distribution of the performance of the two groups in the ergometric tests. The echocardiogram showed a median increase in the diameter of the left atrium and left ventricle of 1-2 mm in the exposed subjects. These differences could also be confirmed statistically after multiple linear regression analysis. The left ventricular, telesystolic diameter was positively associated (P < 0.05) with internal exposure (CS2 metabolite in urine), and fractional shortening revealed a plausible negative trend (P = 0.0755). Current external exposure (CS2 in air) and cumulative exposure did not influence any of the parameters investigated. CONCLUSION: The findings may indicate a negatively inotropic effect of CS2 so far unknown in man. However, no clinical relevance for this effect was apparent.

Carbon Disulfide↗
PubMed1995

Carbon disulphide. III. Risk factors for coronary heart diseases in workers in the viscose industry.

To evaluate risk factors for coronary heart disease and factors which can influence the course of acute myocardial infarction in workers exposed to CS2 we performed a cross-sectional study of 247 workers in the viscose industry. The control group of 222 men from the same plant was comparable for age, social status and physical work. The CS2 exposure determined by personal air sampling ranged from < 0.2 ppm to 65.7 ppm (median: 4.0 ppm) and the duration of exposure ranged from 4 to 220 (median: 66) months. Using a multiple linear regression model we found neither higher blood pressure at rest or after exercise, nor hyperlipoproteinaemia in a higher degree, nor lower high-density lipoprotein (HDL) or lower apolipoprotein A-I levels, nor higher blood glucose values, nor indicators of direct cardiotoxic effects or signs of disturbances in blood coagulation in the exposed group in comparison to controls. Regarding the influence of chronic exposure on the investigated parameters, we found an inverse correlation of the cumulative exposure (mean CS2 exposure in the department multiplied by the duration of work in this department) with the HDL concentration. The HDL levels correlated with the duration but not with the intensity of exposure. In the same way the apolipoprotein A-I levels showed a negative association with the duration of exposure in the exposed group as well as in the control group. The HDL concentrations showed the same trend for the controls. It therefore seems that this finding is more likely due to confounding factors than to the CS2 exposure. As all subjects (exposed and controls) have done shift work, in some cases for a long time, this kind of work could be responsible for the negative relationship between the duration of employment as a shift worker and the apolipoprotein A-I and HDL levels. At the current air-borne levels no significant differences were found between the exposed persons and the controls in the distribution frequency for blood pressure values, lipoproteins, blood glucose, blood coagulation and indicators of direct cardiotoxic effects.

Adult↗
PubMed1993

Low polarization pacing lead for detecting the ventricular-evoked response.

The cardiac response to a pacing pulse is potentially useful for rate adaptive pacemakers and threshold tracking systems. However, until now capture recognition of the ventricular-evoked response by the use of a single electrode for stimulation as well as detection was limited by the electrode polarization. Electronic measures against the stimulus polarization artifact have not been successful due to the variability of the after potential or the requirement of additional battery power. Following the idea of Lewin, Myers and Parsonnet, who introduced the idea of a non-polarizable porous electrode for physiological stimulation, titanium nitride (TiN) and iridium (Ir) coatings with fractal surface structure have been developed with high electro-chemical active surface areas and Helmholtz double-layer capacities of up to 50,000 microF/cm2, thus reducing the polarization artifact significantly. Two types of endocardial leads (10 with a fractal TiN coating and 5 with a fractal Ir coating) were implanted in the apex of the right ventricle and the polarization artifact, as well as the evoked response, was measured. Both types of pacing leads show a 90% reduction in the polarization artifact in comparison to conventional leads. If an autoshort of approximately 20 to 50 ms is applied after the pacing pulse, the polarization artifact of these leads is negligible, thus enabling reliable detection of at least the repolarization phase of the ventricular-evoked response, which is fully sufficient for capture recognition. Additionally, due to their low polarization losses, TiN- or Ir-coated electrodes with fractal surface structure have a unique stimulation and detection performance.

Aged↗
PubMed1990

Sputter-deposited TiN electrode coatings for superior sensing and pacing performance.

The sensing and pacing performance of pacemaker electrodes is characterized by the electrochemical properties of the electrode/tissue interface affecting tissue reactions and the kinetics of the ionic exchange. The usually smooth metallic electrode surface results in a high pass filter characteristic. To better match the electrode's filter characteristic to the spectral content of the depolarization signal, various combinations of electrode shape, material and surface structure have been researched. The electrode with sputter-deposited TiN coating presented in this report has been designed to meet the demand for low acute as well as chronic thresholds and superior sensing performance not only with respect to spontaneous activity but also regarding the detection of the evoked response. The clinical results obtained with this electrode prove the excellent pacing and sensing properties resulting from minimized polarization losses and optimized filtering of the signal to be detected, respectively. The acute and chronic clinical advantages over previous concepts are attributed mainly to the biocompatibility of the material used and the microcrystalline surface structure achieved by the coating process. The design concept of the new electrode is presented together with the clinical results obtained. While the advancements in microelectronics and battery technology have certainly formed the basis for the development of pulse generators featuring an ever increasing versatility of functions at the same or even smaller pacemaker dimensions, from a point of view of pacing system performance the development of improved electrode concepts as the one presented must be regarded as equally indispensable.

Biocompatible Materials↗
PubMed1982

A survey of contrast media used in coronary angiography.

In recent years, various contrast media have been developed for use in coronary angiography. These contrast media may be divided into ionic contrast media of high osmolality, those of low osmolality, and nonionic contrast materials. We conducted our own clinical studies with 40 patients. In random succession a standard contrast medium (ionic, of high osmolality) and a new-generation contrast medium (either nonionic or ionic with low osmolality) were injected into the right and left coronary arteries. After each injection we measured the systolic and diastolic blood pressure using a liquid-filled coronary catheter. In addition, the change in the length of the cardiac cycle was registered in terms of the R-R interval (in ms) and at the same time, leads I, II, and III of the ECG were recorded. We studied the influence of the various contrast media on the activity of ATPase in in vitro experiments, using Lasser and Lang's [30]. When ionic contrast media of low osmolality and nonionic contrast media were utilized the heart rate showed no change. Disturbances of rhythm such as ventricular tachycardia or fibrillation were not observed. All of the contrast media used produced the same ECG changes. These changes can be ascribed to the inhibition of ATPase. The arterial blood pressure was lowered significantly only by ionic contrast media of high osmolality only.

Adenosine Triphosphatases↗
PubMed1979

[High levels of CK and its isoenzymes produced by a thymus carcinoma (author's transl)].

A 63 years old female is described suffering from thymus carcinoma with increased levels of CK and CK-MB enzymes. The separation of the total CK enzymes into the isoenzymes CK-MM, CK-BB, and CK-MB showed a marked difference between the photometric and the immunological method. This discrepancy can be explained by postulating a molecule specific for thymus carcinoma, probably a new CK isoenzyme. The relevance of using the photometric method in cardiologic routine diagnostic is pointed out.

Antibodies↗
PubMed1978

Enzyme changes after coronary angiography.

The enzymatic response to contrast media after coronary angiography was observed in 24 patients. The enzymes studied were glutamic oxaloacetic transaminase (SGOT), glutamic pyruvic transaminase (SGPT), lactic dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (alpha-HBDH), gamma-glutamyl transferase (gamma-GT), creatine phosphokinase (CPK), and the myocardial-specific isoenzyme of CPK (CK-MB). Angiography produced no significant elevations in SGOT, SGPT, alpha-HBDH, LDH, or CK-MB activities; gamma-GT increased up to the twelfth hour. High levels of CPK and CK-MB observed in one patient were found to be products of a thymus carcinoma. In vitro examinations also showed that concentrations of contrast media used in coronary angiography do not inhibit gamma-GT, LDH, and CPK activities.

Adult↗
PubMed1977

[Systolic periods in dependence of age].

In 278 healthy probands in the age of 23 to 80 years were measured the systolic periods and examined in dependence of age. There are found the following results: 1. from the youngest to the oldest group there is a small, statistically not significant increase of the middle systolic period. 2. the presphygmic phase (PEP) and the frequence-corrected interval (PEPI) show a small increase of the middle values in the first four age steps. Only after the age of 60 years is a clear increase of PEP and PEPI. 3. the expulsion time (LVET) and the expulsion index (LVETI) show in an increasing tendency of the mean values no significant difference of the mean value in the age groups. 4. the quotient LVET/PEP follows the course of PEP and PEPI. There is supposed, that the clear statistically significant increase of the mean value of the presphygmic phase and the presphygmic index after the age of 60 years cannot not be reduced to a "physiologic age insufficiency of the heart", but its cause is founded in asymptomatic courses of the coronary heart disease or other defined heart diseases.

Adult↗
PubMed1977

[The resonance frequency of the radial artery in healthy untrained and endurance-trained older men].

There are examined 2 groups of two at a time men over 55 years old, different only in their training state, regarding the reaction of the resonance frequence. It would be established, that the resonance frequence of the A. radials in non-trained is more than the double as in trained probands. The middle resonance frequence increases continuous with the age in both groups. A high resonance frequence in thong-minded trained was not observed, only one time a normal, 63 times a reduced arterial resonance frequence. Under the condition, that the arterial resonance frequence can be regarded as an arterial index, the differences between the resonance frequence of both groups mean, that the biological age of the arteries in trained is on an average younger as in non-trained.

Aging↗
PubMedDate not supplied

[Titanium nitride cardiac pacemaker electrodes].

The sensing and pacing performance of pacemaker electrodes is characterized by the electrochemical properties of the electrodes/tissue layer; the usually smooth metallic electrode surface results in a high pass filter characteristic. Consequently, the detected intracardiac signals, which control the implantable systems, are not optimally matched to the spectral contents of the depolarisation signal. To avoid interference caused by noise (EMI, muscle potentials, etc.) a shift of the frequency of the band pass towards the lower frequency spectrum is required. As previously reported, the electrochemical properties of sintered and surface-treated electrodes prove the predicted improvement of sensing performance if titanium-nitride coated electrodes are used. Our results demonstrate their superiority above all the other electrodes presently known. The advantages can be referred to the micro-crystalline surface structure achieved by sputter-deposited electrode coatings and the kinetics of the ionic exchange. Furthermore, the acute thresholds achieved with the TiN-systems were significantly better than those of the smooth metallic surface. These results were also confirmed for chronic implants and are attributable to the known biocompatibility of titanium and its alloys.

Electrocardiography↗