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Biomedical subjects

A Manz

Publications and source records attributed to A Manz.

At least 55 records · Page 3Linked to original sources
PubMed1993

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Epidemiologic Methods↗
PubMed1993

An integrated silicon thermophile as biosensor for the thermal monitoring of glucose, urea and penicillin.

A new kind of calorimetric biosensor for the measurement of the heat (molar enthalpy change) of enzymatic reactions is presented. The device operates according to the Seebeck effect, the same principle on which thermocouples are based. The thermopile used in this work consists of an array of p-type silicon/aluminium strips integrated on a thin silicon membrane (5 microns). Its sensitivity is about 1 V output voltage per watt of heating power, corresponding to a temperature resolution in the order of 10(-5) K and a heating power resolution of some tenths of a mu W in the flow system used. Furthermore, this performance is obtained without any control of external temperature because of the high common-mode thermal noise rejection ratio of the thermopile. The universal technique of calorimetry combined with the specificity of biochemical reactions makes this biosensor very versatile, with a broad range of possible applications. Glucose oxidase together with catalase for the determination of glucose, urease and penicillinase for the monitoring of urea and penicillin G, respectively, were immobilized directly onto the back side of the thermopile. The sensor was operated in conjunction with flow injection analysis which, in addition to its traditional advantages, allows preconditioning of the samples. Thus, artefacts due to mixing effects were suppressed and interference caused by differences in ionic strength between sample and carrier was strongly decreased. Detection limits between 1 and 2 mM were reported in the flow injection conditions described.

Biosensing Techniques↗
PubMed1992

Cancer of the stomach and the colon-rectum among workers in a coke gas plant.

Four thousand nine hundred and eight male workers of the Hamburg gas plant, employed for 10 or more years during the period from January 1, 1900 to December 31, 1989, have been traced for cancer mortality. Based on their jobs, they were grouped into three subcohorts: gas furnace workers, workers in other parts of the plant, and white-collar workers. Despite the general "healthy worker effect," gas furnace workers showed a significant incidence of cancer of all sites (standardized mortality ratio [SMR] = 186), particularly cancers of the lung (SMR = 288), stomach (SMR = 177), and the colon-rectum (SMR = 184). In comparison to the death rates of white-collar workers, the manual workers in other parts of the plant also showed an excess of cancer mortality for cancer of these sites. The reason for this excess in cancer mortality seems to be due to the working conditions. The results contribute to the current evidence that exposure to coal carbonization fumes causes not only lung cancer, but also cancers of the stomach and colon-rectum.

Adult↗
PubMed1992

Flow injection analysis and in-line biosensors for bioprocess control: a comparison.

Miniaturization will unify the different approaches chosen for the application of biosensors in bioprocess control. The most versatile system, which in our opinion is flow injection analysis will be the method of choice for the introduction of biosensors in bioprocess control. A lot of experience will be gained for the future development of miniaturized total chemical analysis systems.

Biosensing Techniques↗
PubMed1991

Cancer mortality among workers in chemical plant contaminated with dioxin.

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD) can arise as a contaminant in the production of herbicides. It causes chloracne in those exposed to it but its human carcinogenicity has been a matter of dispute. We report here a mortality follow-up of 1583 workers (1184 men, 399 women) employed in a chemical plant in Germany that produced herbicides, including processes contaminated with TCDD. Production of TCDD was reduced from 1954 after an outbreak of chloracne. Vital status up to 1989 was determined for 97.1% of workers hired between 1952 and 1984, and 367 deaths (313 men, 54 women) were recorded. A malignant neoplasm was the underlying cause of death in 93 men and 20 women. Standardised mortality ratios (SMR) were calculated with, as references, national mortality statistics for West Germany and deaths in a cohort of male gas workers; for total cancer mortality they were 1.24 (95% confidence interval 1.00-1.52) and 1.39 (1.10-1.75), respectively, among men. Cancer mortality was increased among men with 20 or more years of employment (SMR = 1.87 [Germany] and 1.82 [gas workers]) and among men who began employment before 1955 (SMR = 1.61 and 1.87). The group with suspected highest exposure to TCDD had SMRs of 1.42 and 1.78. Only 7% of cohort women worked in the high exposure locations in the plant, compared with 39.6% of men, and no increased risk of cancer mortality was observed among women; but breast cancer mortality was raised (SRM = 2.15). These results, together with a US occupational study and a German investigation of accidental exposure, support the hypothesis that TCDD is a human carcinogen.

Cause of Death↗
PubMed1991

[The usefulness of death certificates in epidemiological studies].

An analysis of a total of 189 deaths recorded between 1953 and 1990 from two companies in Hamburg was performed to examine the question whether and if so to what extent differences existed between the causes of death (primary disease) stated in the death certificates on the one hand, and the diagnoses based on subsequent medical (clinical and pathologico-anatomical) reports, on the other. Postmortems were conducted in 94 cases; the diagnoses resulting therefrom had also been taken into consideration in 58 of the pertaining death certificates. Considerable differences were seen for the remaining 36 postmortems where only clinical diagnoses were recorded in the death certificates. In 10 cases (= 27.8%) the statements made in the death certificates did not agree with the PM diagnoses. The overall rate of deviations was 12.7% the figures for the individual fatal diseases varied, the greatest difference occurring with diseases of the heart and with chronic bronchitis and the least difference with acute apoplexy, accidents, suicides and malignant tumours. It is noted that death certificates and hence also the official statistics derived therefrom are but an inaccurate reflection of the actual distribution of causes of death in case of unicausal evaluations. The quota of diagnoses based on PM and actually taken into consideration, is an important factor in this regard. However, the data supplied by the death certificates are reasonably useful for epidemiological studies to estimate the risks involved in certain diseases.

Autopsy↗
PubMed1978

Asymmetry of the chloride transport system in human erythrocyte ghosts.

The concentration dependence of the unidirectional chloride flux and the inhibition of the unidirectional chloride flux by sulfate were studied in human red cell ghosts. The concentration dependence of the unidirectional chloride flux and its inhibition by sulfate were asymmetric. The unidirectional chloride flux can be saturated from the inner and from the outer membrane surface. For the inner membrane surface, lower chloride half-saturation constants were obtained than for the outer membrane surface. The inhibition of the unidirectional chloride flux by sulfate is competitive. In contrast to the chloride half-saturation constants, the inhibition constants of sulfate for the inner membrane surface were higher than the inhibition constants of sulfate for the outher membrane surface. Either there are fixed anion binding sites at the inner and at the outer membrane surface which control the access of anions to a pore, or there is a mobile carrier which is in contact with both membrane surfaces. The asymmetry of the concentration response and of the inhibition of the unidirectional chloride flux suggest that the anion binding sites at the inner and at the outer membrane surface differ with respect to their affinities for chloride and for sulfate. Alternatively, the asymmetry of the chloride transport system could indicate an asymmetric distribution of a mobile anion carrier across the erythrocyte membrane.

Anions↗
PubMed1976

[Urinary tract carcinomas in gas industry employees (author's transl)].

Arising from a retrospective investigation of the causes of death in active and pensioned employees from the author's sphere of observation, the increased occurence of urinary tract carcinoma in furnace battery and pipe system workers in the gas industry is pointed out. Statistical studies suggest a causal connection between exposure to tar in these jobs and the urinary tract carcinomas. The necessity for industrial medical precautions is commented on.

Chemical Industry↗