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Biomedical subjects

M Maiwald

Publications and source records attributed to M Maiwald.

8 recordsLinked to original sources
PubMed1991

[Time series analysis of patient self-assessed psychophysiologic variables].

A data set of physiological (blood pressure, body weight, pulse rate) as well as psychological (adjective list by Sokolow et al.) variables collected by a patient in 1985 is analysed. Initially, by identifying time series models, subsequently, by estimating parameters and, eventually, by cross correlating all variables pair wise. With regard to different time intervals (the whole year, 2-months-intervals) several ARIMA-models apply for a description of the psychophysiological variables. Results obtained by time series analyses are confirmed by spectral analyses. For distinct time sections (i.e. Sep.--Oct., Nov.--Dec.) cross correlations reveal a seven day periodicity which corresponds to a psychophysiological pattern. Time series analyses of single case data are considered as a valuable research strategy which in some cases allows the detection of the underlying processes.

Affect↗
PubMed1990

Possible role of acetaldehyde in ethanol-related rectal cocarcinogenesis in the rat.

Prospective epidemiologic studies have reported an increased risk of rectal cancer following chronic ethanol ingestion. The effect of ethanol on chemically induced colorectal carcinogenesis is controversial depending on the experimental conditions. In the present study the effect of chronic ethanol administration on acetoxymethylmethylnitrosamine-induced rectal cancer and the possible role of acetaldehyde in this process were investigated. Chronic ethanol administration resulted in an earlier occurrence of rectal tumors in this animal model. Because the concomitant administration of cyanamide, a potent acetaldehyde dehydrogenase inhibitor, showed a positive trend toward increased incidences of tumors, acetaldehyde could be involved in the ethanol-associated carcinogenesis. To measure colonic acetaldehyde, 12 chronically ethanol-fed and control rats received an acute dose of ethanol (2.5 g/kg body wt). The mucosal concentration of acetaldehyde was significantly higher in the rectum compared with the cecum (198 +/- 23 vs. 120 +/- 23 nmoles.g colon-1, p less than 0.05), but was not affected by chronic ethanol feeding. Furthermore, 6 germ-free rats had significantly lower acetaldehyde concentrations in the rectum (84 +/- 11 vs. 234 +/- 33 nmoles.g colon-1, p less than 0.01) and in the cecum (59 +/- 13 vs. 121 +/- 33 nmoles.g colon-1, p less than 0.05) compared with 6 conventional animals, and this was paralleled by the number of fecal bacteria in the 2 intestinal segments. In addition, to determine the effect of chronic ethanol feeding on colorectal cell turnover, 30 animals were pair-fed liquid diets. Using the metaphase-arrest technique, alcohol feeding induced rectal (19.1 +/- 2.0 vs. 9.1 +/- 1.8 cells.crypt-1.h-1, p less than 0.01), but not cecal (18.9 +/- 1.3 vs. 22.2 +/- 3.3 cells.crypt-1.h-1, p greater than 0.05) hyperregeneration. This was accompanied by an increase in the crypt proliferative compartment and increased mucosal ornithine decarboxylase activity (63 +/- 18 vs. 22 +/- 6 pmoles.hr-1.mg protein-1, p less than 0.05). The data show that chronic ethanol ingestion accelerates chemically induced rectal carcinogenesis and raise the possibility that acetaldehyde probably generated through bacterial ethanol oxidation may be involved in this process. The secondary hyperregeneration of the mucosa, observed after alcohol feeding, could by itself favour carcinogenesis.

Acetaldehyde↗
PubMed1990

Prediction of clinical outcome of radiation accident victims.

On the basis of the analysis of more than 350 individuals that were exposed to ionizing radiation in the course of more than 25 radiation accidents reported world wide since 1945, a biomathematical computer model was developed that simulates the pattern of granulocyte changes seen. It allows one to calculate the number of stem cells remaining intact to initiate recovery. It is shown that the major question to be asked is whether a spontaneous stem cell recovery can be expected or not. This question can be readily answered within 3-5 days after radiation exposure on the basis of the constellation of hematopoietic findings and devised stem cell pool size calculations.

Accidents↗
PubMed1988

[Principles of a medical-psychological long-term single case study].

Using time plots of serial measurements of physiologic as well as psychologic parameters (blood pressure, body weight, pulse rate and an adjective list by Sokolow) possible evaluation strategies applicable to extended data sets are demonstrated. The data set used in this study has been compiled over a seven year period by daily sampling of the aforementioned parameters by a male patient. Preliminary findings indicate, that covariation between parameters differs, when data of distant time sections are considered.

Adult↗
PubMed1987

[The enzymatic degradation of formaldehyde by isolates of Pseudomonas aeruginosa].

The capacity of 12 Ps. aeruginosa-strains to enzymatically degrade Formaldehyde was tested. These strains, derived from environmental and patient samples, were previously passaged 25 times in increasing formaldehyde-concentrations, in a micromodification of the bacteriostasis test. The formaldehyde-degradation was detected photometrically with the sulfite-pararosaniline-method. Furthermore, in 4 of the 12 strains the activity of a formaldehyde dehydrogenase assumed to be the degrading agent was determined. The tested strains exhibited a markedly differing resistance to formaldehyde, some environmental isolates growing even at concentrations in the range of commonly used disinfectant solutions. The exponential growth phase of the inoculum and the reduction of formaldehyde-content coincided. The strains with the highest formaldehyde-resistance showed a formaldehyde-dehydrogenase activity higher by approximately a factor 100 compared with the rather sensitive ATCC-strain. This dehydrogenase activity, in addition to possible extra- and intracellular penetration barriers, could be a causal factor for an increased formaldehyde-resistance.

Aldehyde Oxidoreductases↗
PubMed1987

[Verbal interaction and heart rate in the course of the therapeutic process in a neurotic patient. A psychobiologic pilot project].

Whereas measurements of physiologic variables are widely used in investigations of psychosomatic illnesses, this proceeding is not an established strategy when dealing with the therapeutic process of neuroses which lack coarse bodily symptoms. Therefore, we investigate the heart rate response pattern and the verbal dialog during therapeutic sessions of a patient with an impulsive neurosis. Recordings are made before and after the obsessive symptoms improve. Changes are found in the heart rate response as well as in the verbal interaction between patient and therapist. While symptoms persist the patient's behavior alternates between patient and therapist. While symptoms persist the patient's behavior alternates between gross defense and a panic like disturbance. Concurrently the heart rate response shows an inconspicuous pattern interrupted by sudden heart rate increases. After the obsessive symptoms had ceased the patient has been better controlled in his behavior but is more tense. Compared to the previous state this is accompanied by more frequent and longer lasting periods of reduced heart rate variability and only moderate increases.

Adult↗