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Biomedical subjects

L Larsson

Publications and source records attributed to L Larsson.

At least 289 records · Page 16Linked to original sources
PubMed1986

Heating cells in acid methanol for 30 min without freeze-drying provides adequate yields of fatty acids and alcohols for gas chromatographic characterization of mycobacteria.

We studied the release of mycobacterial fatty acids (as methyl esters) and secondary alcohols after heating both wet and freeze-dried cells in methanolic hydrogen chloride for different time periods. A 30-min heating of the mycobacteria without prior freeze-drying was found adequate in a routine gas chromatographic procedure for strain and species characterization.

Alcohols↗
PubMed1986

Proximal tubular reabsorption and Na-K-ATPase activity in remnant kidney of young rats.

In rats unilaterally nephrectomized (NX) in infancy, the compensatory growth of the remnant kidney is due first to hypertrophy and hyperplasia, but after 2 wk only to hyperplasia. We studied proximal tubular adaptation (reabsorption, Na-K-ATPase activity, length, and basolateral membrane area) 2 and 8 wk after NX. The rats were NX at 5 days of age. The size of remnant kidney obtained from uninephrectomized rats was 125% at 2 wk and 179% at 8 wk relative to the appropriate time-related controls. Single-nephron glomerular filtration rate in the uninephrectomized group was doubled relative to controls, whereas fractional reabsorption by the proximal tubule was unchanged. Na-K-ATPase activity per millimeter of proximal convoluted tubule (PCT) was significantly increased in the uninephrectomized group relative to controls at 2 but not 8 wk. The area of the basolateral cell membrane per millimeter PCT was unchanged at both 2 and 8 wk, which suggests that the density of enzyme units inserted in the membrane was increased at 2 but not at 8 wk. PCT length was increased at 8 but not at 2 wk. There was a close correlation between total PCT Na-K-ATPase activity and filtered sodium (r = 0.999) and between total PCT Na-K-ATPase activity and PCT sodium reabsorption (r = 0.998). We conclude that the proximal tubule can adapt to an increased filtered load by increasing the density of transporting units or by increasing the tubular length. The latter stage may be attained only in young growing animals.

Absorption↗
PubMed1985

Effects of long-term physical training and detraining on enzyme histochemical and functional skeletal muscle characteristic in man.

The adaptability of human skeletal muscle to increased (training) and decreased (detraining) usage was studied in 11 athletes over a 42-month-long observation period. Biopsies were taken from the deltoid and the quadriceps muscle, together with measurements of maximum torque output during voluntary knee extensions at high relative to slow speeds of movement. A 16% and 14% decrease in the proportion of type I fibers was seen in the proximal arm and leg muscles, respectively, in the detraining subjects. This conformed with the changes in muscle function. On the other hand, in the training subjects, who increased their activity level through systematic daily physical training over an almost 4-year-long period, there were no significant changes seen in fiber type proportions of either arm or leg muscles. This was presumably due to the smaller net change in physical activity level caused by training as compared to detraining in the subjects of this study. Thus, the results show that fiber type proportions in intact human skeletal muscle are not exclusively determined by heredity, but may also be influenced by environmental factors, such as physical activity level.

Acclimatization↗
PubMed1985

Gas chromatographic fatty acid profiles for characterisation of mycobacteria: an interlaboratory methodological evaluation.

Three species of mycobacteria were cultured and processed for cellular fatty acid analysis by capillary gas chromatography in three laboratories to study interlaboratory variations of the resulting chromatographic profiles. Largely consistent and characteristic fatty acid profiles were obtained, although there were minor quantitative variations in the patterns due to methodological differences (cultivation, hydrolysis, derivatization, gas chromatographic conditions etc.). The following points were important for achieving informative and reproducible results. A chemically defined growth medium (e.g., Proskauer-Beck) provides more consistent profiles than the lipid-rich Löwenstein-Jensen medium. Harvesting directly into the digesting solution (NaOH or HCl in methanol) followed by heating or autoclaving is a simple and reliable way of releasing fatty acids. Care should be taken to ensure reproducible detection of long-chain alcohols either by using acid methanolysis or including a base-wash step in the procedure following alkaline hydrolysis. The temperature of the gas chromatographic injector should be at least 325 degrees C. A capillary column of a minimum length of 10 m coated with a methyl silicone is adequate. Our results indicate the possibility of recommending a practical and reproducible gas chromatographic procedure for mycobacterial characterisation.

Chromatography, Gas↗
PubMed1985

Posterior vitreous detachment. A combined clinical and physiochemical study.

Sixty-one postmortem eyes were examined with clinical methods (slit lamp) and later sectioned for measurement of the liquid and gel vitreous. The amount of liquid vitreous was found to be progressively greater with increasing posterior vitreous detachment (PVD), and it was concluded that slit-lamp examination is a reliable method of evaluating the rheological state of the vitreous in the living eye. The total content of sodium hyaluronate (NaHA) in the vitreous was measured. Eyes proven to have no PVD had a higher concentration of NaHA than eyes with total PVD. Also, females had a lower concentration than males. There was no significant difference in NaHA concentration between the gel and liquid vitreous. The role played by different structural elements for the stability of the vitreous gel is discussed.

Aged↗
PubMed1985

Influence of culture medium and incubation time on the fatty acid compositions of some rapid-growing mycobacteria as analysed by packed and capillary column gas chromatography.

Cellular fatty acids of four rapid-growing mycobacterial species (Mycobacterium chelonei, M. fortuitum, M. phlei, and M. smegmatis) were analysed by packed and capillary column gas chromatography after one, three, four, six, eight, and twelve days of incubation on Löwenstein-Jensen and Sauton agar media. Variations in incubation time did not affect the chromatograms except in the case of twelve-day incubated M. smegmatis. Mycobacteria cultivated on Sauton agar medium contained more tuberculostearic and less oleic acid compared with Löwenstein-Jensen. For informative and reproducible analytical results, we recommend using a chemically defined culture medium and splitless injection on a capillary column capable of separating not only the methyl esters of the cellular fatty acids but also the diagnostically important secondary alcohols containing 18 and 20 carbon atoms.

Chromatography, Gas↗
PubMed1985

Contractile properties, fatiguability and glycolytic metabolism in fast- and slow-twitch rat skeletal muscles of various temperatures.

The influence of muscle temperature (28 and 36 degrees C) on fatiguability and glycolytic metabolism was studied during 5 min of intermittent stimulation of motor nerves of the tibialis anterior, extensor digitorum longus (fast-twitch) and soleus (slow-twitch) muscles in the rat at 100 Hz (200 ms per s). The decline in isometric tension was not affected by muscle temperature either in fast- or in slow-twitch muscles. In fast-twitch muscles the utilization of glycogen during stimulation was the same at 28 and 36 degrees C, while in the soleus muscle it was lower at 28 degrees C. The concentration of glucose-6-phosphate immediately after stimulation was higher in the muscles at 28 degrees C than in those at 36 degrees C, whereas no difference in lactate concentration was found between the two temperature groups. These observations indicate that compared with the rate at 36 degrees C, the rate of glycogenolysis at 28 degrees C is unchanged in fast-twitch, but decreased in slow-twitch muscle. This might imply increased economy of ATP turnover during contraction in the soleus muscle at 28 degrees C.

Animals↗
PubMed1985

Ontogeny of triamcinolone-acetonide binding sites in outer cortical tissue from rat kidneys.

The ontogeny of glucocorticoid binding sites and the glucocorticoid hormone (GC) feedback control of available glucocorticoid binding sites was studied using the cytosolic fraction of outer cortical tissue obtained from kidneys in 20- and 40-day-old intact and adrenalectomized rats. Morphometric analysis showed that this tissue contained 85.7% (20 days) and 88.7% (40 days) of proximal tubular cells. Glucocorticoid binding sites were determined by [3H]triamcinolone-acetonide (TA) binding and isoelectric focusing analysis. In intact rats, TA binding sites (fmol/mg DNA) were significantly higher at 20 (3,624) than at 40 (1,640) days. Adrenalectomy significantly increased TA binding sites (fmol/mg DNA) at 40 (to 8,445) but not at 20 days. TA binding sites related to DNA were significantly higher in 20- than in 40-day-old intact rats and significantly higher in 40- than in 20-day-old adrenalectomized rats. Serum corticosterone (nM) was not significantly different in 20- (230) and 40- (189) day-old rats. After in vivo administration of a synthetic GC, TA binding sites were replenished to the cytosol after 20-24 h. Prolonged GC treatment (1-60 micrograms X 100 g body wt-1 X day-1) depressed the replenishment of TA binding sites significantly more in 40- than in 20-day-old adrenalectomized rats. Kd was determined in both intact and adrenalectomized 20- and 40-day-old rats and ranged between 1.30 and 4.33 nM. The steroidal specificity for the TA binding sites was the same in 20- and 40-day-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1985

Effects of pneumococcal vaccination on tonsillo-pharyngitis and upper respiratory tract flora.

The effect of a 14-valent pneumococcal vaccine on upper respiratory tract infections and carriage of beta-haemolytic streptococci was studied in a double-blind prospective study of 405 children 0.5-5 years of age. In the children under 2 years of age at vaccination, the cases of acute tonsillitis were more frequent among the vaccinees than among the controls (p less than 0.01). In contrast, among the children over 2 years of age at vaccination, fewer episodes of acute tonsillitis were reported among the vaccinees than among the controls (p less than 0.01). In the older age group, the total rate of upper respiratory tract infections was also significantly reduced. Similarly, an increase in asymptomatic carriage of group A streptococci was registered in children vaccinated at 2-5 years of age (p less than 0.01). Inversely, the carriership of group C streptococci diminished among the vaccinated children (p less than 0.05). Some possible mechanisms underlying these unexpected findings, including non-specific mitogenic features and cross-protection due to antigenic similarities, were explored.

Age Factors↗
PubMed1985

Carbonic anhydrase in the metanephrogenic zone of the human fetal kidney.

The distribution of carbonic anhydrase in the metanephrogenic zone of the human fetal kidney was studied by the histochemical method of Hansson. In stage I nephrons (= renal vesicles) no or very little enzyme activity was found. Adjacent cortical collecting tubules, however, showed enzyme activity at the luminal cell surface. In stage II nephrons (= S-shaped tubules) the tubular cells displayed cytoplasmic carbonic anhydrase activity, while the glomeruli were inactive. Thus, the development of the nephron from stage I to stage II was accompanied by an increase in tubular cell carbonic anhydrase activity with partially another distribution than in the adult kidney. This may indicate an additional function of this enzyme in the developing nephron other than in the process of urinary acidification, e.g. to promote normal growth and differentiation of the tubular cells.

Carbonic Anhydrases↗
PubMed1985

Factors influencing the time long-term indwelling Foley catheters can be kept in situ.

To study the factors that influence the frequency of unscheduled catheter changes, patients with long-term indwelling Foley catheters were followed up for 48 weeks. A marked interindividual difference in the need for unscheduled changes was noted. The amount and composition of the encrustations precipitated on the catheters and urine osmolality influenced the frequency of unscheduled catheter changes. There was no correlation between the time a catheter had been in situ and the amount of encrustations on catheters changed on schedule after various times in situ. This indicates that time does not govern the amount of encrustations accumulated.

Adult↗
PubMed1985

Measurement of ionized calcium with five types of instruments. An external quality assessment.

An external quality assessment for ionized calcium determinations was carried out in 24 laboratories in Northern Europe. Both protein-free and protein-containing test materials were included in the study. The average within-laboratory variation (CV) for all test materials was 3.1, 1.7, 1.2, 1.8 and 1.3% for the AVL 980 (AVL, Graz, Austria), the Microlyte (Kone, Espoo, Finland), the Nova 2 (Nova Biomedical, Newton, Ma USA), the Orion SS-20 (Orion, Cambridge, Mass., USA), and the ICA1 (Radiometer, Copenhagen, Denmark) respectively. The corresponding interlaboratory CV was 3.1, 2.9, 3.1 and 2.4%. The variation between types of instruments was even larger and caused differences of up to 33%. The results indicate a need for well-defined protein-containing control material.

Calcium↗
PubMed1985

Design, findings and five-year follow-up of preventive medical lipid intervention clinic in Malmö.

In a separate lipid intervention clinic integrated within the framework of a multiphasic preventive medical population program in Malmö, 401 of 2431 screening attenders in a male birth-year cohort born in 1927 and 1928 had elevated values of triglyceride and/or cholesterol. Hypertriglyceridemia was more than three times as frequent as hypercholesterolemia. Of these attenders 20% had normal values at the second control, 5% did not attend the second test and 92 (31.2%) of the remaining were referred to other clinics because of other high risk factors. Thus, 209 (8.6% of the screening attenders) males born in 1927 and 1928 attended the lipid clinic for isolated hyperlipidemia. Disregarding a 5-year drop-out frequency of 13 sections, a significant reduction in the lipids was obtained during the follow-up period in those remaining in treatment. This study demonstrates the feasibility in taking care of hyperlipidemic individuals after a screening detection program. Detection and treatment of hyperlipidemia should of course also be initiated in the individual case in ordinary medical practice.

Cholesterol↗
PubMed1985

UVA photosensitivity in photosensitive bullous disease of chronic renal failure.

3 chronic renal failure patients with bullous skin disease are reported. Only 1 was on maintenance hemodialysis, but all were on frusemide. Porphyrin studies failed to show classical porphyric disease. The 3 patients tested showed low minimal etyrhema doses (MED) to ultraviolet A (UVA) but normal threshold to ultraviolet B (UVB).

Adult↗