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Biomedical subjects

T Nurminen

Publications and source records attributed to T Nurminen.

36 records · Page 2Linked to original sources
PubMed1985

Birth defects and exposure to video display terminals during pregnancy. A Finnish case-referent study.

In a test of the widely publicized allegation that exposure to video display terminals causes birth defects, interview forms of mothers of 1 475 children reported consecutively to the Finnish Register of Congenital Malformations to have defects of the central nervous system, orofacial clefts, skeletal defects, or cardiovascular malformations and the forms of the same number of their paired referents were studied. The scrutiny revealed 490 mothers with occupational titles indicating potential exposure to video display terminals. Of the 490, 235 were case mothers and 255 were referents. Then, unaware of the case-referent status, three members of the research team perused the mothers' interview descriptions of workday activities for information indicating exposure to video display terminals. Work with such terminals during the first trimester of pregnancy was ascertained for 111 mothers. Of these, 51 were case mothers and 60 were referents. The comparison of the mothers exposed to video display terminals during the first trimester with those not exposed at all showed a crude odds-ratio point estimate of 0.9 with 95% confidence limits of 0.6 and 1.2. Adjustment for potential confounders by multivariate logistic regression methods did not materially affect the risk estimates. The results did not indicate a teratogenic risk for operators of video display terminals.

Adult↗
PubMed1983

Screening for occupational exposures and congenital malformations.

Since 1976 the Finnish matched-pair Register of Congenital Malformations has been linked to a special project which screens for associations between selected congenital malformations and chemical and physical exposures during early pregnancy. Case mothers and their referents are personally interviewed. Exposure data are quantitated blindly by a team of industrial hygienists and occupational health experts. An analysis of data from 1,047 pairs is now underway. The pairs consist of 289 defects of the central nervous system, 421 orofacial clefts, 200 selected structural malformations of the skeleton, and 137 selected cardiovascular defects. Exposure to organic solvents was associated with defects of the central nervous system in the initial two-year material. However this association was no longer detectable during the following three-year period. More pairs must be gathered before a reasonable judgment regarding the teratogenic potential of solvents becomes possible.

Abnormalities, Drug-Induced↗
PubMed1976

Distribution of membranes, especially of plasma-membrane fragments, during zonal centrifugations of homogenates from glucose-repressed Saccharomyces Cerevisiae.

1. The distributions of several enzymes and other marker components were examined after zonal centrifugations of whole homogenates from glucose-repressed Saccharomyces cerevisiae on sucrose and iso-osmotic Ficoll, and the composition and morphology of the fractions were investigated. 2. After high-speed zonal centrifugation most of the protein, acid and alkaline phosphatases, alkaline pyrophosphatase, adenosine monophosphatase, beta-fructofuranosidase, alpha-mannosidase, NADPH-cytochrome c oxidoreductase and an appreciable amount of phospholipid and sterol were non-sedimentable, i.e. were at densities below 1.09 (g/cm3). Most of the RNA was at p=1.06-1.08 in Ficoll and at p=1.09-1.11 in sucrose. 3. The bulk of the Mg2+-dependent adenosine triphosphatase (Mg-ATPase) was coincident with the main peak of phospholipid and sterol, at median density 1.10, which was also rich in smooth-membrane vesicles. In Ficoll, a minor peak of phospholipid and sterol at p-1.12-1.15 contained a smaller part of the oligomycin-insensitive Mg-ATPase and heavy membrane fragments. In sucrose, several minor peaks of Mg-ATPase were in the mitochondrial density range, and a peak of oligomycin-insensitive Mg-ATPase coincident with a minor peak of phospholipid and sterol at around p-1.25 contained heavy membrane fragments of high carbohydrate content, especially mannose. 4. Further purification of the oligomycin-insensitive Mg-ATPase containing membrane preparations was performed on Urografin gradients. 5. It is argued that the oligomycin-insensitive Mg-ATPase containing membranes are fragments of the plasma membrane, but have different densities because they contain different amounts of glycoprotein particles.

Acid Phosphatase↗
PubMed1975

Neutral lipids in the cells and cell envelope fractions of aerobic baker's yeast and anaerobic brewer's yeast.

The neutral lipids from whole cells and cell envelopes of aerobic Saccharomyces cerevisiae and anaerobic Sacch. carlsbergensis and the cell walls isolated from the cell envelopes were analysed. The effect of anaerobiosis was particularly clear on the neutral lipid composition of the plasma membrane. Compared to the anaerobic membrane, the aerobic membrane contained more C16:1, C18:1 and other unsaturated fatty acids, more total sterol, more than ten times as much ergosterol and less than one tenth as much squalene, reflecting differences between the aerobic and anaerobic whole cellmthe main sterol in the aerobic membrane ergosterol, was mainly in the free form, whereas zymosterol, 24(28)-dehydroergosterol, epi- or fecosterol and lanosterol were predominantly esterified. In contrast, the anerobic membrane contained small amounts of biosynthetic sterol precursors of ergosterol (mainly esterified), and was clearly richer in saturated fatty acids having a greater variation in chain length and in 18:2 acid. Both plasma membranes contained a considerable amount of triacyglycerols, while the amount of lower acylglycerols was clearly higher in the anaerobic plasma membrane. The lipid composition of both cell walls were relatively similar, consisting mainly of triacylglycerols and lower acylglycerols.

Aerobiosis↗
PubMed1974

The cell-envelope glycolipids of baker's yeast.

Sphingolipids were found to dominate in the glycolipids from the cell envelope of baker's yeast. A relatively large quantity of ceramides was detected. Among the several complex phosphosphingolipids described, ceramide-(P-inositol)(2)-mannose was the main component. About 55% of long-chain bases in sphingolipids consisted of C(18)-phytosphingosine (4D-hydroxysphinganine). Other bases, found in decreasing concentrations, were C(20)-phytosphingosine, C(20)-dehydrophytosphingosine, C(18)-dihydrosphingosine (sphinganine) and C(19)-dihydrosphingosine. The presence of sterol glycosides, sulpholipids, cerebrosides and acylglucoses was demonstrated.

Cell Membrane↗
PubMed1971

Occurrence of long-chain fatty acids and glycolipids in the cell envelope fractions of baker's yeast.

1. The total yield of fatty acids from the whole envelopes was markedly higher than that obtained from the ordinary cell walls. In both samples the major fatty acids were C(16) and C(18) acids. 2. The whole envelopes contained C(18) acids and long-chain (C(19)-C(26)) fatty acids, in a higher proportion than did the ordinary cell walls. Fifteen fatty acids with more than 18 carbon atoms were identified, among which 2-hydroxy-C(26:0) and C(26:0) acids predominated. 3. A complex sphingolipid containing inositol, phosphorus and mannose was isolated from the whole cell envelopes. The main fatty acids of this lipid were 2-hydroxy-C(26:0) and C(26:0) acids. It was concluded that this sphingolipid is present both in the ordinary cell wall and in the plasma membrane of baker's yeast. 4. The neutral lipids amounted to over 50% and the glycerophosphatides to about 30% of the total fatty acid content of the whole envelope. The major fatty acids in these lipids were C(16:1), C(18:1) and C(16:0) acids. The proportion of fatty acids with more than 18 carbon atoms was lowest in the neutral lipids, whereas the neutral glycolipids contained the highest percentage of these fatty acids. Acidic glycolipids amounted to 14% of the total fatty acid content of the whole envelope. The presence of a cerebroside sulphate in this lipid fraction was demonstrated, whereas the high content of 2-hydroxy-C(26:0) acid found is caused by the complex inositol- and mannose-containing sphingolipid.

Cell Fractionation↗
PubMed1970

The enzymic composition of the isolated cell wall and plasma membrane of baker's yeast.

A study was made of the enzyme content of the isolated cell walls and of a plasma-membrane preparation obtained by centrifugation after enzymic digestion of the cell walls of baker's yeast. The isolated cell walls showed no hexokinase, alkaline phosphatase, esterase or NADH oxidase activity. It was concluded that these enzymes exist only in the interior of the cell. Further, only a negligible activity of deamidase was detectable in the cell walls. Noticeable amounts of saccharase, phosphatases hydrolysing p-nitrophenyl phosphate, ATP, ADP, thiamin pyrophosphate and PP(i), with optimum activity at pH3-4, and an activity of Mg(2+)-dependent adenosine triphosphatase at neutral pH, were found in the isolated cell walls. During enzymic digestion, the other activities appearing in the cell walls were mostly released into the medium, but the bulk of the Mg(2+)-dependent adenosine triphosphatase remained in the plasma-membrane preparation. Accordingly, it may be assumed that the enzymes released into the medium during digestion are located in the cell wall outside the plasma membrane, whereas the Mg(2+)-dependent adenosine triphosphatase is an enzyme of the plasma membrane. This enzyme differs from the phosphatases with pH optima in the range pH3-4 with regard to location, pH optimum, substrate specificity and different requirement of activators.

Adenine Nucleotides↗
PubMed1970

The lipolytic activities of the isolated cell envelope fracttions of Baker's yeast.

1. The existence of phospholipase and lipase activities in the isolated cell envelopes of baker's yeast was demonstrated. 2. The content of phospholipase was found to be markedly higher than that of lipase. 3. After partial enzymic digestion of the isolated cell envelopes, the bulk of the lipolytic activities was recovered in the sedimentable preparations, which consisted of the fragments of the plasma membrane. 4. During repeated washings, the lipase was completely released from the cell envelopes, as were also the bulk of the lipid components and most of the Mg(2+)-dependent adenosine triphosphatase, an enzyme connected with the plasma membrane. The phospholipase was more firmly bound to the preparation but not so firmly as the external saccharase. 5. These results indicate that the lipolytic enzymes found in the cell envelopes are mostly located in the plasma membrane.

Adenosine Triphosphatases↗
PubMedDate not supplied

Low-back pain in nurses and some loading factors of work.

Questionnaires were sent to qualified nurses (QNs) and nursing aides (NAs) to study the prevalence of low-back pain (LBP) and sciatica in relation to age, work-load, free time activities, menstruation, pregnancies and number of children. LBP and sciatica severe enough to make them unfit for daily tasks were significantly more common in NAs. Back injury and disability pension due to sciatic symptoms were also more common in NAs. Occupationally, NAs had twice the amount of lifting, bending, and rotation, while QNs reported more sitting and standing at work. Under the age of 30, the heaviness of the work was related to LBP in both NAs and QNs. It was concluded that prevention should be directed to improvements in the occupational work load, particularly for younger nurses.

Adult↗
PubMedDate not supplied

Radiographic versus direct measurements of the spinal canal at lumbar vertebrae L3-L5 and their relations to age and body stature.

The role of the narrow lumbar spinal canal in back and sciatic pain is well established. The accuracy of measurements obtained from lumbar radiographs was therefore analyzed in lumbar spine specimens taken from 132 male cadavers. After removal of soft tissues, the same distances were measured on the bones of 80 specimens. Comparisons were made after correction for magnification, the radiographic measurements of interpedicular distances being, on average, 2 mm greater at L3 than the osteologic ones and 4 mm greater at L5. Interarticular distances, midsagittal diameters, and pedicular lengths were, on average, 1 mm greater and foraminal anteroposterior measurements 1 mm less than the osteologic ones. Body stature correlated with interpedicular and interarticular distances, pedicular length, and foraminal anteroposterior measurements. In older age groups, the midsagittal diameter tended to be reduced. A number of correlations were found between the five measurements, e.g. between the anteroposterior diameter of the intervertebral foramen and the pedicular length. Measurements in the transverse plane were independent of those in the anteroposterior plane. These results confirm and amplify preliminary observations and indicate the potential value of simple measurements on lumbar spine films as an alternative to more sophisticated and expensive radiologic investigations.

Adult↗