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Biomedical subjects

M Andersen

Publications and source records attributed to M Andersen.

At least 145 records · Page 8Linked to original sources
PubMed1980

Mutagenic action of isocyanates used in the production of polyurethanes.

Isocyanates used in the production of polyurethanes were investigated for mutagenic action in Salmonella typhimurium. These investigations showed that the most commonly used isocyanates, toluene diisocyanate (TDI) and 4,4'-methylene-diphenylisocyanate (MDI), are mutagenic. This effect can be ascribed to the amine analogues formed during the hydrolysis of isocyanates: TDI is mutagenic in TA 1538 and TA 98 after metabolic activation. This finding agrees with the results obtained with the amine analogue 2,4-toluenediamine. MDI, like the amine analogue 4,4'-methylenedianiline, is mutagenic in TA 100 after metabolic activation by rat liver enzymes (S-9 mix). A prepolymerized polyisocyanate of the MDI type is also mutagenic in assays using TA 100 and S-9 mix. It is concluded that isocyanates are potentially mutagenic and carcinogenic to man. In view of their widespread use in the work environment and in light of the high production figures for polyurethanes in industrialized countries, isocyanates must be considered to represent a serious health hazard.

Cyanates↗
PubMed1980

Clinical and laboratory findings in patients subjected to laparotomy for suspected acute appendicitis.

In a retrospective study, clinical and laboratory findings in 454 patients subjected to laparotomy for suspected acute appendicitis were evaluated. A normal appendix was found in 25% of the total series and was twice as common in female as in male patients. Perforated appendicitis was present in 8% of the series, most commonly in the youngest (less than 5 years) and the oldest (greater than 40 years) age groups. The incidence of severe appendicitis increased with the duration of the preoperative abdominal symptoms. Of the patients with a 'laboratory profile' including fever and leukocytosis, 44% had gangrenous or perferated appendicitis. Of those who additionally had elevated ESR (greater than 20 mm), 62% showed a gangernous or perforated appendicitis. The overall incidence of wound infection was 13.9%. Wound infection was closely related to the state of the appendix. The results thus indicated that patient's age, duration of abdominal symptoms and the 'laboratory profile' are important parameters for assessment of clinically suspected acute appendicitis.

Acute Disease↗
PubMed1980

Obstetric practice amongst Queensland general practitioners: a survey of needs and attitudes.

A survey of Queensland general practitioners was carried out to assess their needs and attitudes regarding obstetric practice. Less than half of the respondents now practise obstetrics, and many general practitioners felt a lack of support from specialist obstetricians, paediatricians, and anaesthetists. Many of the respondents expressed needs for further obstetric training, especially in labour ward management and neonatal care; however, few were able to attend extended courses.

Adult↗
PubMed1979

Thyroid replacement therapy in Down's syndrome with hypothyroidism.

Three elderly subjects with Down's syndrome and biochemical evidence of hypothyroidism were investigated before and after four months of thyroid replacement treatment. The patients' appearance was demonstrated by photographs and the biochemical thyroid values and the intellectual performance were assessed. The appearance before treatment varied from a florid myxoedematous appearance to a state without features indicating myxoedema. Thyroid replacement therapy was given in usual dose and the biochemical response was similar to that seen in normal subjects. The intellectual performance improved little or not at all. The characteristic discomfort usually associated with hypothyroidism was very pronounced in one case and disappeared totally during treatment. It is concluded that the diagnosis of hypothyroidism in elderly subjects with Down's syndrome can be very difficult when based on appearance and history alone and biochemical thyroid tests are often necessary. The patients should be treated with replacement therapy just as other patients suffering from hypothyroidism.

Down Syndrome↗
PubMed1979

Can postoperative pulmonary conditions be improved by treatment with the Bartlett-Edwards incentive spirometer after upper abdominal surgery?

During the immediate postoperative course after upper abdominal surgery, pulmonary complications often occur, caused, inter alia, by reduced regional ventilation and by atelectases as a result of: (1) narrowing of the small peripheral bronchi, and (2) impaired respiratory function. Based on these pathophysiological mechanisms, an instrument (Bartlett-Edwards Incentive Spirometer) has been devised, which aims at giving the patient an opportunity of sustained maximal inspiration under standardized and controlled conditions. The use of this instrument has been followed by reports of a considerable reduction in postoperative pulmonary complications. In a controlled clinical investigation of the pre- and postoperative condition of the lungs, we were unable to show any beneficial effect of the instrument. In general, we have a low frequency of severe postoperative pulmonary complications, as compared with the results reported in the literature. We ascribe this to our very effective pre- and postoperative respiratory therapy.

Abdomen↗
PubMed1978

Mutagenicity of fume particles from metal arc welding on stainless steel in the Salmonella/microsome test.

Mutagenic activity of fume particles produced by metal arc welding on stainless steel (ss) is demonstrated by using the Salmonella/microsome mutagenicity test described by Ames et al., with strain TA100 (base-pair substitution) and TA98 (frame-shift reversion). Results of a representative but limited selection of processes and materials show that mutagenic activity is a function of process and process parameters. Welding on stainless steel produces particles that are mutagenic, whereas welding on mild steel (ms) produces particles that are not. Manual metal arc (MMA) welding on stainless steel produces particles of higher mutagenic activity than does metal inert gas (MIG) welding, and fume particles produced by MIG welding under short-arc transfer. Further studies of welding fumes (both particles and gases) must be performed to determine process parameters of significance for the mutagenic activity.

Gases↗
PubMed1977

Van der Waals interactions between cell surfaces.

Van der Waals energies of interaction between model cell surfaces are calculated for various distances of separation, layer thicknesses and compositions of cell surfaces and intercellular media. In these calculations the cell peripheries are considered to consist of two layers: (1) A phospholipid-cholesterol-protein plasma membrane and (2) a surface coat, which consists of protein, sugar and water. The required Van der Waals parameters of sugars, phospholipids and cholesterol are derived from refractive indices of their solutions in the visible and ultraviolet regions. Polarizabilities and Van der Waals parameters of these substances are determined and shown to be almost independent of concentration of solutions. Resulting isotropic polarizabilities differ by less than five percent from values obtained by the addition of bond polarizabilities. The magnitude of Van der Walls interactions between cell surfaces has been found to vary with composition according to the following sequence: water less than phospholipid less than cholesterol, protein less than sugar. A decrease in the concentration of a given substance in the cell surface at the expense of a corresponding increase in the concentration of a substance preceding it in this sequence lowers the magnitude of attractive interactions, whereas a similar change in the extracellular medium would have an opposite effect. A consideration of experimentally found variations in composition of cell surfaces results in calculated values of Hamaker's coefficients between 8 X 10(-15) ergs and 6 X 10(-14) ergs at 50 A distance of separation, which corresponds to free energies per unit area of 210-1600 kT/mu2.

Carbohydrates↗