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Biomedical subjects

L Larsson

Publications and source records attributed to L Larsson.

At least 235 records · Page 13Linked to original sources
PubMed1989

Crystal violet binding, cell surface properties and extracellular enzyme profiles of Staphylococcus aureus producing toxic shock syndrome toxin-1.

Staphylococcus aureus isolated from clinically diagnosed cases of toxic shock syndrome (TSS) showed susceptibility to phage types belonging to both I and III groups (90.5%). Phage typing patterns showed a wide diversity among 87 toxic shock syndrome toxin-1 (TSST-1) positive strains isolated from different non TSS clinical sources. Toxin producing strains isolated from both TSS and non TSS showed a remarkable ability to bind to crystal violet (pattern C/D, 97.2%) incorporated into brain heart infusion agar media at subinhibitory concentrations and these isolates were traced to biotype var. hominis. The cellular fatty acid compositions of TSS and non-TSS strains belonging to the three biotypes S. aureus var. hominis, S. aureus var. bovis and S. aureus var. canis did not differ. TSST-1 producing strains demonstrated a high salt aggregation test value (above 1.5) indicating a low cell surface hydrophobicity. Both TSS and non TSS strains demonstrated a high lipolytic activity. TSST-1 positive strains in general, showed significantly higher lipase activity than strains isolated from septicemia (p less than 0.0001) and superficial (p less than 0.0001) infections. The proteolytic activity is higher among TSS (median value 0.075 U/ml) than to non TSS (median value 0.045 U/ml) strains. There was no correlation with the quantity of toxin production in vitro and to the properties described.

Bacterial Toxins↗
PubMed1989

Familial hypocalciuric hypercalcaemia: a study of four kindreds.

Four kindreds with hereditary hypercalcaemia have been investigated. Thirty-seven of 72 subjects examined had hypercalcaemia with an autosomal dominant pattern of inheritance. Hypercalcaemic patients had total serum calcium of 2.91 +/- 0.12 mmol l-1. Serum parathyroid hormone (PTH) was normal while daily urinary calcium excretion was subnormal (below 2.5 mmol) in 45%. Comparison with an age-matched group of patients with primary hyperparathyroidism gave a small overlap regarding serum human PTH, urinary calcium and the ratio between calcium clearance and creatinine clearance. Family screening therefore is of diagnostic importance. Twelve subjects had been subjected to parathyroid surgery before the correct diagnosis was settled, none of the cases had an adenoma. Three patients became normocalcaemic and the others had persistent hypercalcaemia. One male non-abuser had seven episodes of acute pancreatitis before surgery and none after. The findings in all four kindreds are compatible with familial hypocalciuric hypercalcaemia (FHH). This hereditary disorder of unknown aetiology, therefore, also exists in Scandinavia. It is of importance to consider FHH in the differential diagnosis of hypercalcaemia, since this disorder usually has a benign prognosis if untreated.

Calcium↗
PubMed1989

Plasma ionized calcium, phosphate and magnesium in preterm and small for gestational age infants.

Blood concentrations of ionized calcium, phosphate and magnesium were determined on days 1, 3 and 5 in 32 preterm infants, appropriate for gestational age, and 25 small for gestational age infants. The results were compared with those of a reference group of 31 fullterm newborns. Preterm infants had lower mean ionized calcium levels than the reference population. Ionized calcium levels were positively correlated with gestational age and postnatal age. The sickest infants had the lowest calcium levels. Intrauterine growth retardation did not seem to influence the calcium levels. Small for gestational age infants had lower phosphate values than the reference group and the values correlated with the degree of growth retardation the first day. Magnesium concentrations increased with time and did not differ significantly between the study groups and the reference group. Magnesium values did not correlate with calcium or phosphate values.

Calcium↗
PubMed1989

A novel type of delayed tension reduction observed in rat motor units after intense activity.

1. A delayed reduction of tetanic tension during recovery from fatigue, produced by repeated tetanic contractions, has been found in isolated amphibian muscle fibres (Westerblad & Lännergren, 1986). We have now followed the recovery in a mammalian muscle preparation to see if a similar phenomenon may appear also in mammalian muscles. 2. Single motor units of the rat tibialis anterior muscle were fatigued by 200 ms-80 Hz stimulation trains, initially delivered every 4 s and then at decreasing intervals until tension was depressed to about 30% of the original. 3. After about 10 min of recovery tetanic tension was almost normalized. Tension then decreased in most units to a minimum, which occurred after 30-100 min of recovery. At this stage tension outputs ranged from 6 to 95% of controls. 4. The EMG amplitude was also followed and like tension it was first almost normalized and then depressed. Generally the EMG depression was bigger than the tension loss; the EMG amplitudes were also somewhat reduced in the units not displaying any clear force reduction. 5. Both tetanic tension and EMG amplitude recovered gradually from the depressed state and values similar to controls were eventually reached. 6. In conclusion, we have found a novel type of delayed tension reduction in mammalian muscle during recovery after fatiguing contractions. The exact cause of this reduction is presently unclear, but an important contribution from impaired excitation-contraction coupling is highly plausible.

Animals↗
PubMed1989

Effects of age on calcium transport activity of sarcoplasmic reticulum in fast- and slow-twitch rat muscle fibres.

1. The calcium transport activity of the sarcoplasmic reticulum (SR) was measured in chemically skinned single fast- and slow-twitch muscle fibres from young (3 months) and old (23-24 months) rats. Contractile properties, the myosin heavy chain (MHC) composition and enzyme histochemical features were studied in relation to the SR characteristics. 2. In fast-twitch single motor units, the contraction time of the isometric twitch increased (P less than 0.001) from 13 +/- 1 ms in young animals to 18 +/- 2 ms in old ones. In the slow-twitch soleus, the contraction (P less than 0.001) and half-relaxation (P less than 0.05) times increased from 30 +/- 5 and 45 +/- 10 ms, respectively, in the young animals to 43 +/- 3 and 55 +/- 4 ms in the old ones. The proportion of slow-twitch (type I) fibres increased (P less than 0.05) with age in the soleus from 92 +/- 6 to 98 +/- 2% and the proportion of fast-twitch fibres (type IIA) decreased (P less than 0.01) from 6 +/- 5 to 0 +/- 0%. 3. The Ca2+ accumulation capacity (an index of SR volume), the rate of Ca2+ uptake and the fractional rate of SR filling (an estimate of the specific activity of the Ca2+ pump) were decreased by 18 (P less than 0.05), 32 (P less than 0.01) and 32% (P less than 0.001), respectively, in the old fast-twitch muscle fibres. In the slow-twitch muscle fibres, on the other hand, no significant age-related changes were observed in the Ca2+ transport activity of the SR. Thus, ageing exerts a differential influence on SR volume and function in fast- and slow-twitch fibres. 4. It is concluded that an age-related impairment of intrinsic SR function and a decrease in SR volume are probable factors underlying the decreased speed of contraction of fast-twitch muscle fibres in old age. In the slow-twitch soleus, on the other hand, one or more other mechanisms are responsible for the age-related decrease in the speed of contraction. The loss of fast-twitch muscle fibres in old soleus is one mechanism, but not the dominant one.

Age Factors↗
PubMed1989

Two-dimensional gas chromatography with electron capture detection for the sensitive determination of specific mycobacterial lipid constituents.

A method was developed for determining two characteristic mycobacterial lipid constituents, tuberculostearic acid (as its pentafluorobenzyl ester) and 2-eicosanol (as its pentafluorobenzoyl ester), by using gas chromatography with electron capture detection. A microprocessor-controlled column-switching system (two-dimensional gas chromatography) facilitated sample preparation and increased specificity. The usefulness of the technique was illustrated by its ability to reveal picogram amounts of tuberculostearate in a suspension of Mycobacterium leprae isolated from a naturally infected armadillo. Two-dimensional gas chromatography with electron capture detection may in some instances provide a convenient alternative to gas chromatography-mass spectrometry for use in demonstrating the presence of mycobacteria in a complex environment.

Animals↗
PubMed1989

Establishment of 2-docosanol as a cellular marker compound in the identification of Mycobacterium xenopi.

Sixteen strains of Mycobacterium xenopi were studied by gas chromatography and thin-layer chromatography. Data on the cellular fatty acids, fatty alcohols, mycolic acids, and glycolipids indicated that this bacterium possesses a specific lipid composition. 2-Docosanol, detected in all studied strains, was found to constitute a useful chemical marker in the identification of M. xenopi.

Biomarkers↗
PubMed1989

Immunocytochemical localization of intracellular acidic compartments: rat proximal nephron.

There is evidence that components of the endosomal-lysosomal system of most cells have an acidic interior. The weak base, N-(3-[(2,4-dinitrophenyl)amino]propyl)-N-(3-aminopropyl)methylamine dihydrochloride (DAMP) has been shown to accumulate in acidic compartments in cultured cells and in isolated perfused proximal tubules. We infused DAMP intravascularly in vivo and used colloidal gold immunocytochemistry to identify acidic compartments in cells of the rat glomerulus and proximal tubule. Sprague-Dawley rats were infused intra-arterially with DAMP. The kidneys were fixed by intravascular perfusion with 1% glutaraldehyde and embedded in Lowicryl K4M. Sections were exposed to a mouse anti-dinitrophenol (DNP) monoclonal antibody that cross-reacts with DAMP, followed by gold-conjugated goat anti-mouse immunoglobulin G. Transmission electron microscopy revealed positive labeling of the lysosome-like structures of the various cells of the glomerulus and lysosomes, endosomes, and numerous endocytic vesicles of all segments of the proximal tubule. We conclude that 1) DAMP can be used in vivo to identify acidic compartments in the kidney and 2) lysosomes, endosomes, and many endocytic vesicles of the rat proximal tubule as well as lysosome-like structures in cells of the glomerulus have an acidic interior.

Acids↗
PubMed1989

An electrophysiological method for monitoring blood flow in skeletal muscle. An experimental study in the rat.

An experimental animal model was used to study the effects of occlusion of skeletal muscle blood flow on spontaneous denervation activity (fibrillation potentials). The aim was to investigate whether recording of fibrillation potentials could provide a valuable electrophysiological technique for monitoring muscle tissue circulation during free flap surgery. In both the fast-twitch anterior tibial muscle and the slow-twitch soleus, the number of fibrillation potentials decreased rapidly (within 30 sec) after occlusion of the blood flow and after 5 min only few fibrillation potentials were present. In the fast-twitch muscle, the fibrillation potentials disappeared within 10 min in most animals, but sporadic potentials were seen for up to 18 min in one animal after the blood vessels were clamped. In the slow-twitch muscle, sporadic single fibrillation potentials were seen for a longer time than in the anterior tibial muscle and fibrillation potentials were often observed for more than 20 min after clamping of the blood vessels. However, the initial decrease in the number of fibrillation potentials was rapid in both muscles. This means, if the same is true in human muscle, that the method is sufficiently rapid to permit restoration of the circulation so that the muscle flap can be saved if the blood flow is occluded after a muscle transfer operation. Thus, recording of fibrillation potentials may provide a powerful and simple technique for monitoring free flap circulation.

Animals↗
PubMed1989

Effect of hematocrit and added heparin on ionized calcium in capillary blood samples from neonates.

Sampling of capillary blood for determination of ionized calcium (Ca2+) in neonates requires that extra heparin be added to prevent clotting in the sampling tube and (or) in the Ca2+ analyzer. Because the additive dissolves in the plasma compartment, different hematocrit (erythrocyte volume fraction, EVF) values may cause different results for Ca2+. To study the effect of EVF and heparin additive, we repeatedly removed plasma, thereby increasing the EVF. These samples with different EVF's were aspirated into commercial capillary tubes containing heparin and, according to our routine procedure, an additional 10 microL (approximately 0.9 int. unit) of sodium heparin. We found a negative bias of 0.05-0.09 mmol/L in Ca2+, depending on the EVF. Adding saline instead of heparin gave the same effect, indicating that this bias was entirely due to dilution. We suggest compensating for this by adding 0.09 mmol/L to the actual value for ionized calcium when EVF exceeds 70%. The increase in Ca2+ in neonates on days 1 to 5 postpartum is physiological and not an effect of change in EVF.

Calcium↗
PubMed1988

Angiogenic properties of Kaposi's sarcoma-derived cells after long-term culture in vitro.

Cells derived from lung biopsies and pleural effusions from AIDS patients with Kaposi's sarcoma (KS) of the lungs were established in long-term culture with the aid of conditioned medium from HTLV-II-transformed T cells (HTLV-II CM). These AIDS-KS cells were similar to the so-called spindle cells in KS lesions and had some of their features. They produced factors that supported their own growth (autocrine) and the growth of other cells (paracrine), including umbilical vein endothelium and fibroblasts. That the AIDS-KS cells also expressed potent angiogenic activity was demonstrated by the chorioallantoic membrane assay and by subcutaneous inoculation of AIDS-KS cells into nude mice, which resulted in the development of angiogenic lesions composed of mouse cells and showing histological features similar to those of human KS lesions. These data suggest that AIDS-associated KS and possibly other types of KS may be initiated by signals that induce the growth of particular cells (spindle cells of lymphatic or vascular origin) and the expression of autocrine and paracrine activities.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Determination of environmental levels of peptidoglycan and lipopolysaccharide using gas chromatography with negative-ion chemical-ionization mass spectrometry utilizing bacterial amino acids and hydroxy fatty acids as biomarkers.

D-Alanine and diaminopimelic acid originating from bacterial peptidoglycans and hydroxy fatty acids from lipopolysaccharides (endotoxins) were analysed by gas chromatography using a chiral column (Chirasil-Val as stationary phase) and selected-ion monitoring detection with negative-ion chemical-ionization mass spectrometry. The amino acids were analysed as N-heptafluorobutyryl isobutyl esters after rapid hydrolysis of peptidoglycan followed by isolation of the amino acids with disposable ion-exchange columns. Racemization of amino acid enantiomers was controlled by using deuterium chloride in the hydrolysis. The hydroxy acids were analysed as O-pentafluorobenzoyl methyl esters. Most of the bacteria present in airborne dust from a poultry confinement building were found to be Gram-positive according to the analytical chemical method whereas the Limulus amoebocyte lysate test suggested the presence of appreciable amounts of lipopolysaccharides of Gram-negative bacteria. Further studies are required to compare the utility of these two methods for determining endotoxins in complex environments.

Amino Acids↗
PubMed1988

S-100 protein and neuron-specific enolase in amniotic fluid as markers of abdominal wall and neural tube defects in the fetus.

The aim of this study was to determine whether there is increased leakage of neuron-specific enolase (NSE) and S-100 protein into amniotic fluid in pregnancies with neural tube defects, since both these proteins are produced by neural tissue, and to compare the value of these substances for detecting such defects with that of the more conventional techniques of alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) gel electrophoresis. Amniotic samples from 25 mid-pregnancies (15-17 weeks' gestation) with neural tube defects (14 with open spina bifida and 11 with anencephaly) and from seven mid-pregnancies with abdominal wall defects were compared with a control material consisting of 80 amniotic fluid samples from 80 consecutive mid-pregnancy amniocenteses, with normal karyotypes and AFP concentrations. All of the above cases of abnormalities were primarily detected through increased AFP levels in the amniotic fluid. Amniotic fluid samples from 13 pregnancies with fetuses with autosomal chromosomal abnormalities and seven amniotic fluid samples contaminated with blood were also included in the investigation. It is concluded from the results that the conventional AFP assay combined with AChE gel electrophoresis is the best method for screening amniotic fluid for neural tube defects and defects of the abdominal wall. Neither NSE nor S-100 assay alone proved to be superior for the detection of these cases in mid-trimester amniotic fluid. The S-100 assay, however, could give additional information in cases where AChE gel electrophoresis is not decisive; for example, in samples contaminated with blood.

Abdominal Muscles↗
PubMed1988

Kidney function in adults born with unilateral renal agenesis or nephrectomized in childhood.

We have evaluated the long-term prognosis in an unselected group of adult patients either uni-nephrectomized in childhood because of hydronephrosis or born with unilateral renal agenesis. Thirty-six patients aged 7-47 years were followed for 7-40 years. In 23 control subjects aged 20-47 years the glomerular filtration rate (GFR) and the p-aminohippuric acid clearance (CPAH) did not change significantly with age. In patients with a single kidney the size of that kidney was larger and GFR and CPAH were higher than single kidney values in control subjects. However, in patients with a single kidney since childhood the GFR and the CPAH declined slowly but significantly during the follow-up period. Significant microalbuminuria occurred in 47% of the patients with a single kidney and was more frequent with a longer follow-up period. No patient had renal insufficiency or a marked increase in arterial blood pressure. We conclude that in patients with a single kidney since childhood the long-term prognosis is good, but the late decrease in GFR and increase in albumin excretion may indicate a moderate risk for premature renal damage.

Adaptation, Physiological↗
PubMed1988

Proglumide treatment in bile-induced acute experimental pancreatitis.

Rats with acute experimental pancreatitis were treated with the cholecystokinin (CCK)-receptor antagonist proglumide. S-amylase was not affected by proglumide during the initial 4 h but was reduced after 72 h as compared to pre-pancreatitis values. The amylase levels in peritoneal fluid were lower in proglumide treated animals at 1, 2, 4 and 72 h after the induction of the pancreatitis, and amylase in pancreatic tissue was increased by proglumide after six but not 72 h. In spite of these biochemical changes, suggesting beneficial therapeutic effects by proglumide, survival rate was not improved when using a dose of 100 mg/kg every 8 h for 48 h and significantly reduced at a dose of 500 mg/kg every 8 h for 48 h. The results do not support proglumide as the sole treatment in acute pancreatitis.

Acute Disease↗
PubMed1988

Effects of the interval between removal and freezing of muscle biopsies on muscle fibre size.

Measurements of cross-sectional fibre areas are often performed in routine histopathologic diagnosis in cases of suspected neuromuscular disease. The methodologic error in fibre area measurements in duplicate muscle biopsies is reported, however, to be high and an animal model was therefore designed in order to study the mechanisms underlying this. The cross-sectional fibre area in the right soleus muscle, cut into 5 pieces and frozen after different lengths of time, was compared with that in the left soleus, which was frozen at the in situ length. It was found that this area was 23 +/- 6% larger (P less than 0.001) than in the control muscle, when the muscle sample was frozen immediately after being taken, as a result of contraction of the specimen. However, when the interval between removal of the sample and freezing was 2 min or longer, the fibre size was similar to the control muscle, but the muscle samples were still contracted and the decrease in muscle fibre size at longer intervals were accordingly due to a decrease in muscle fibre volume. It is concluded that the interval between removal and freezing of the biopsy is of vital importance for the fibre size.

Animals↗