Biomedical subjects

G Sundström

Publications and source records attributed to G Sundström.

At least 55 records · Page 3Linked to original sources

PubMed1980

Quantitative electron microscopic studies on rat ileal Paneth cells under various physiological and experimental conditions.

The Paneth cells of the rat ileum were studied with quantitative electron microscopical methods. Estimations were made of the average volume of the cells and the nucleus, and the mean diameter and volume density of the secretory granules. Six groups of rats, each comprising 6-7 animals, were investigated: the rats in the first group were fasted controls, those in the second group non-fasted controls. In the third group the rats were given pilocarpine and in the fourth atropine. In the fifth group the rats were chemically sympathectomized, and the rats in the sixth group were subjected to partial removal of the small intestine. The secretory granules remained unchanged in all groups, except for the atropinized rats which contained significantly increased amounts, presumably indicating a low secretory rate. Moreover, the secretory granules were smaller in the rats treated with pilocarpine and in those operated on; this probably reflects a high secretory rate.

Animals↗

PubMed1979

Chlorinated phenoxyacetic acid derivatives and tetrachlorodibenzo-p-dioxin in foliage after application of 2,4,5-trichlorophenoxyacetic acid esters.

Six reforestation areas were sprayed with 2,4,5-T esters. Leaf samples from the areas were analyzed for the esters, tetrachlorodioxin, and dehalogenated phenoxyacetic acid esters. Tetrachlorodioxin was found in one leaf sample only, but the level found, relative to the amount of 2,4,5-T ester found, was lower than in the formulation material used in the study. The concentration of the dichlorophenoxyacetic acid esters present in several leaf samples was greater, relative to the 2,4,5-T ester, which indicated a photochemical breakdown of the 2,4,5-T in the environment.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1979

Metabolism of chlorodiphenyl ethers and Irgasan DP 300.

1. In the rat chlorodiphenyl ethers are metabolized via two routes. The predominant reaction is aromatic hydroxylation; scission of the ether bond is a minor metabolic process. 2. In all cases, primary hydroxylation takes place ortho and meta to the ether bond. Ortho-hydroxylation leads to the formation of 'predioxins' in cases where the parent compounds contain a chlorine atom in one of the ortho positions in the second ring. 3. 5-Chloro-2-(2,4--dichlorophenoxy)phenol (Irgasan DP 300), a compound that meets the structural requirements of a predioxin, did not yield chlorodibenzo-p-dioxins or hydroxylated derivatives thereof. 4. Irgasan DP 300 is excreted unchanged in faeces and urine (partly conjugated) but is also hydroxylated to five different monohydroxy metabolites which were found in urine; three of these were also present in faeces. As a result of scission of the ether bond 2,4-dichlorophenol occurred in urine and faeces, and 4-chlorocatechol in urine. 5. Neither in the case of Irgasan DP 300, nor in that of chlorodiphenyl ethers with an ortho chlorine atom, could metabolic cyclization to chlorodibenzofurans or their hydroxylated derivatives be detected.

Adipose Tissue↗

PubMed1978

Esophageal manometry in pregnant and nonpregnant women.

Esophageal and gastric tone was recorded in six pregnant and six nonpregnant women by means of a new technique for intraluminal pressure recordings. The recordings were performed in supine and standing positions, at rest, and during swallowing of saliva or water. It was found that the pregnant women had lower intraesophageal pressures but higher intragastric pressures compared to the nonpregnant women. In one of the pregnant women a negative pressure situation was recorded between the stomach and lower esophagus. This patient also complained of severe heartburn when she was lying down. Gastroesophageal reflux seems to be aggravated in pregnant women since esophageal peristalsis in these patients has lower wave speed and lower amplitude compared to nonpregnant women.

Adult↗

PubMed1977

Lateral-hole catheters compared with shielded-hole catheter systems in oesophageal manometry.

Water-filled catheters with lateral holes in the distal ends are frequently used in oesophageal manometry. However, the outward position of the recording holes makes mucosal interference a possible risk. A pilot study of oesophageal manometry was performed in five healthy volunteers comparing a conventional lateral-hole catheter with the orifices directed to the centre of the catheter bundle, protected from the mucosa. The centre-hole catheter curves showed a lower resting pressure in the upper oesophageal sphincter (UOS) showed a lower resting pressure in the upper oesophageal sphincter (UOS) and a more rapid decline of the UOS peristaltic wave. The motility curves of the oesophageal body were identical with both catheters.

Adult↗

PubMed1976

Lung function studies in asymptomatic individuals with moderately (Pi SZ) and severely (Pi Z) reduced levels of alpha1-antitrypsin.

Extensive physiological evaluation of lung function were conducted in two groups of asymptomatic individuals with deficiencies of alpha1-antitrypsin: seven subjects with phenotype Pi SZ and six subjects with phenotype Pi Z. Four symptomatic individuals of Pi Z type were also investigated. The asymptomatic individuals of both SZ and Z phenotypes revealed reduction of elastic recoil, hypoventilation and hypoperfusion of the lung bases with increased closing and nitogen wash-out volumes. No signs of bronchial obstruction were observed. The asymptomatic Pi SZ subjects revealed as many signs of subclinical disease as did the asymptomatic Pi Z subjects. These data suggest that Pi SZ subjects are at increased risk of emphysema similar to Pi Z subjects.

Adult↗

PubMed1976

Environmental chemistry of substitutes for polychlorinated biphenyls. I. Composition and properties of an alkylchlorobiphenyl product.

The composition of a technical alkylchlorobiphenyl mixture, proposed as a substitute for polychlorinated biphenyls, has been investigated by spectral and chromatographic methods. Gas-liquid chromatography-mass spectrometry revealed the presence of a large number of biphenyls substituted with 2-3 chlorine atoms and 0-4 isopropyl groups. The mixture was dechlorinated as a first step toward structure elucidation of the individual components. The behavior of the alkylchlorobiphenyls during analytical cleanup steps such as thin layer chromatography and chromic acid oxidation was also investigated.

Alkylation↗

PubMed1975

Influence of body position on pulmonary diffusing capacity in yound and old men.

Steady-state diffusing capacity (DLCOSS2), studied in healthy nonsmokers, was significantly higher in five old men when seated than when supine, but was unchanged in five young men. However, "corrected" for the increased ventilation, it decreased in the young--but not in the old--when erect compared with when supine. The change of DLCOSS2 in the young during the first 20 min when seated was related to a change of the fractional dead space ventilation (VD/VT)mThe old showed less venous admixture when seated than when supine, whereas VD/VT and regional ventilation-perfusion index of the lung bases was the same in both positions. The decrease in venous admixture was probably due to the closing capacity (CC) being less than the functional residual capacity (FRC) when seated. The elimination of closed off regions when seated made more pulmonary capillaries available for diffusion.

Adult↗

PubMed1975

Influence of ventilation, exercise, and body position on techniques for determining steady state diffusing capacity.

Three different methods of measuring steady state diffusing capacity were analysed regarding the effect of using either the physiological dead space for CO2 (DLCOss1), the measured anatomical dead space (DLCOss2), or an assumed anatomical dead space of the lungs (DLCOss3) for the determination of alveolar CO. The material consisted of 28 healthy men and 91 patients with various pulmonary diseases. DLCOss1 and DLCOss2 were compared in the total material (Section 1) using determinations both at rest and during exercise. As was expected DLCOss1 was almost always higher than DLCOss2. The difference between the two methods followed the curve that could be predicted from the mathematically obtained relation between DL, VD/VT, and fractional CO uptake, published by West in a diagram 1962. In determinations with a large sum of the latter two variables, DLCOss1 was highly dependent on the validity of the PaCO2 used. The validity of an end-tidal sample under different ventilatory patterns is investigated in Section 2 and the relation between DLCOss and alveolar ventilation in Section 3. Relative hypoventilation gave low values for DLCOss regardless of method. There was a rapid increase in DLCOss with increasing alveolar ventilation in the normal ventilation range. During hyperventilation DLCOss1, like FuCO, decreased with increasing ventilation. The composition of the end-tidal sample was frequently distorted under forced breathing with large VT so that erroneously high VDa and DLCOss2 were computed. Consequently, DLCOss2 appeared positively correlated to VE and VT over the whole ventilation range. On the other hand, the uncertainty of the size of the anatomical dead space--assumed in DLCOss3--at high flow rates in the bronchial tree reduces the usefulness of this method during pronounced hyperventilation.

Adult↗

PubMed1974