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L Larsson

Publications and source records attributed to L Larsson.

At least 145 records · Page 8Linked to original sources
PubMed1995

Determination of muramic acid in organic dust by gas chromatography-mass spectrometry.

A method is described for the quantitation of muramic acid, a marker of bacterial peptidoglycan, in organic dust. House dust samples were hydrolysed in hydrochloric acid and then extracted with hexane to remove hydrophobic compounds. The aqueous phase was evaporated, heated in a silylation reagent to form trimethylsilyl derivatives, and analysed by gas chromatography--mass spectrometry. The muramic acid derivative gave two peaks upon injection into the gas chromatograph--mass spectrometer. Injection of 10 pg of the derivative gave a signal-to-noise ratio of 17 for the dominating peak when using selected ion monitoring in the electron impact mode, and a linear calibration curve was achieved upon analysis of samples containing 5-1500 ng of muramic acid. In a house dust sample, 40 ng of muramic acid was found per mg of dust; the coefficient of variation was 8.2% (n = 6, 1.2 mg of dust analysed). The described method is rapid and simple to apply, and should therefore become widely used for measuring peptidoglycan in many types of environmental samples, including organic dust.

Air Microbiology↗
PubMed1995

Determination of ergosterol in organic dust by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed for the determination of ergosterol in organic dust. Samples were hydrolyzed under alkaline conditions, and the hydrolysate was extracted, purified on a silica-gel column, and subjected to derivatization. The limit of detection of the trimethylsilyl ether derivative of ergosterol was approximately 10 pg and that of the tert.-butyldimethylsilyl ether derivative was approximately 20 pg (injected amounts). House dust contained 6-45 micrograms ergosterol/g and air from a pig barn contained 0.2-0.3 ng ergosterol/liter. The proposed method can be used as a complement or alternative to microscopy and culturing for measuring fungal biomass in air-borne organic dust.

Aspergillus↗
PubMed1995

The effect of oral magnesium substitution on pregnancy-induced leg cramps.

OBJECTIVE: Our purpose was to determine whether women with pregnancy-related leg cramps would benefit from oral magnesium supplementation. STUDY DESIGN: Seventy-three women with pregnancy-related leg cramps were interviewed about their symptoms in a prospective, double-blind, randomized trial. Initial serum magnesium levels and diurnal magnesium excretion was determined in 50% of the patients. Oral magnesium or placebo was given for 3 weeks, after which new interviews and laboratory analyses were performed. RESULTS: Serum magnesium levels in these patients were at or below the lower reference limit, as is also often the case in healthy pregnant patients. Oral magnesium substitution decreased leg cramp distress (p < 0.05 compared with the placebo group, p < 0.001 compared with initial complaints), but did not significantly increase serum magnesium levels, excess magnesium being excreted as measured by an increase in urinary magnesium levels (p < 0.002). CONCLUSION: Oral magnesium supplementation seems to be a valuable therapeutic tool in the treatment of pregnancy-related leg cramps.

Administration, Oral↗
PubMed1995

Contractile properties in single muscle fibres from chronically overused motor units in relation to motoneuron firing properties in prior polio patients.

The relation between motoneuron firing rate in vivo and maximum velocity of unloaded shortening (Vmax) and myosin isoform composition in single chemically skinned muscle fibres was investigated in chronically overused motor units. Ten patients with loss of a large proportion of the motoneuron pool due to a prior polio lesion and compensatory overuse of residual neurones were studied and compared with normal individuals. The tibialis anterior muscle (TA) was chosen and prior polio patients who used all residual TA motor units at high rates during the normal step cycle were selected. In prior polio patients, all motor units fired at approximately 40 Hz when maximum voluntary force was reached. A common firing rate of 30 Hz yielded 70-90% maximum force. In normal subjects, on the other hand, maximum TA force was reached when low threshold units fired at 25-30 Hz and high threshold units at 50 Hz. Myosin heavy chain (MHC) and light chain (MLC) isoforms were resolved by 6% and 12% sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), respectively, and quantified densitometrically. In the whole biopsy cross-sections, types I, IIA and IIB MHC proportions were 97, 3 and 0% in a typical prior polio patient and 65, 25 and 10% in an age- and sex-matched control subject. Vmax differed significantly (p < 0.001) between type I fibres from the patient (0.54 +/- 0.12 ML/s) and the control subject (0.29 +/- 0.08 ML/s). The composition and relative contents of essential and regulatory MLC isoforms differed in single type I MHC fibres from the control subject and prior polio patient. 65% of the fibres co-expressed the fast and slow isoform of the regulatory light chain (MLC2) in the patient, while this combination was only observed in one of the control type I fibres. All prior polio fibres with a Vmax higher than 0.45 ML/s, except one, co-expressed MLC2s and MLC2f and the only control fibre co-expressing the slow and fast MLC2 isoform had the highest Vmax (0.50 ML/s) among control fibres. On the other hand, a high relative content of MLC3 was not associated with a high Vmax in type I MHC fibres. It is suggested that the composition of fast and slow isoforms of MLC2 has a significant modulatory influence on Vmax within type I MHC fibres. This combination of MLCs and high Vmax in type I MHC fibres is probably induced by chronic motor unit overuse and an altered motoneuron firing pattern.

Adult↗
PubMed1995

Isolation of Mycobacterium malmoense from the environment in Zaire.

Two strains of mycobacteria isolated from water and soil in Zaire were identified as Mycobacterium malmoense by biochemical tests and lipid analysis. Apart from the previously reported fatty acids characteristic of this species, both strains, as well as 5 clinical isolates of M. malmoense, contained 2,4-dimethyl-docosanoic acid. One of the environmental strains, with a glycolipid pattern II, additionally contained 2-methyltetradecanoic acid. The results confirm that M. malmoense may be subdivided in 2 sub-groups according to its lipid patterns. They also show that M. malmoense can be isolated from the environment which may be the source of the infection.

Democratic Republic of the Congo↗
PubMed1995

Motor units: remodeling in aged animals.

The effects of aging on motor units of different types and the spatial arrangement of motor units are discussed. This article is, however, not a comprehensive survey of the literature, but rather a summary of our own results with the addition of relevant reports. The glycogen depletion technique was used to identify the muscle fibers in a motor unit (motor unit fibers). The motor unit fibers were subsequently characterized according to immunocytochemical, enzyme-histochemical and morphometrical properties, and the spatial arrangement was determined with the aid of a computer-assisted model. An age-related motor unit transformation was observed in both fast- and slow-twitch rat skeletal muscles as was a rearrangement of motor unit fibers. The spatial redistribution of motor unit fibers, higher innervation ratios, and larger motor unit territories in old age indicate an age-related denervation-reinnervation process due to loss of alpha-motoneurones.

Adaptation, Physiological↗
PubMed1995

Validation and application of a new simple strategy for measurements of urinary leukotriene E4 in humans.

To monitor endogenous production of cysteinyl-containing leukotrienes, the end-metabolite leukotriene E4 (LTE4) was analysed in urine. Results obtained with a sensitive enzyme immunoassay (EIA), performed on crude urine samples correlated well with data obtained from a previously reported radioimmunoassay. Enzyme immunoassay analysis of unextracted urine was justified by an excellent agreement between analyses in crude samples and measurements achieved after purification on solid phase extraction followed by separation on reversed-phase high performance liquid chromatography. Moreover, LTE4 was stable in urine samples stored at -20 degrees C, for months without the addition of preservatives. The stability of LTE4 in urine was not improved by addition of the antioxidant 4-hydroxy-TEMPO and pH adjustment to 9. As assessed by EIA analysis in crude urine samples, baseline values for urinary leukotriene E4 were not significantly different between atopic asthmatic subjects and non-asthmatic individuals, and there was no diurnal variation in urinary excretion of LTE4 in healthy subjects. However, we confirmed earlier data on significantly higher basal levels of urinary LTE4 in aspirin-intolerant asthmatics. In addition, a post-challenge increase in urinary LTE4 levels was detected in association with allergen-induced airway obstruction in atopic asthmatics. The per cent increase in urinary LTE4 was similar, irrespective of whether the samples were purified or not prior to EIA. Thus, combined with random validation by high performance liquid chromatography, the strategy of direct EIA of serially diluted urine samples was found to be a good index of in vivo production of leukotrienes. This was further reinforced by the demonstration that pretreatment with the leukotriene biosynthesis inhibitor Bay x 1005 inhibited the post allergen-challenge increase in urinary LTE4, as shown both with unpurified and purified samples.

Allergens↗
PubMed1995

Differences in utilization of asthma drugs between two neighbouring Swedish provinces: relation to treatment in individuals with airway disease.

OBJECTIVE: To assess the extent to which drugs were used by individuals found to have asthma in a population survey. To assess the relative influence of the proportion of patients treated and doses reported on the sales of drugs. To study if observed differences in sales of asthma drugs between the county of Jämtland (with high sales) and Gävleborg (with lower sales) correlated to a difference in the control of the disease. DESIGN: A cross-sectional population study with a postal questionnaire followed by an interview and examination of symptomatic individuals. Asthma was diagnosed in subjects reporting a typical history of asthma or repeated episodes of dyspnoea and wheezing, or dry cough combined with reversibility in FEV1, PEF-variability or PC20 < or = 4 mg ml-1. SETTING: The county of Jämtland, and Gästrikland, a southern part of the county of Gävleborg in central Sweden. SUBJECTS: All 16 year olds, and 13% (randomly selected) of 30-39 and of 60-69 year olds (totalling 12732 individuals). Subjects reporting airway symptoms in the questionnaire (n = 2100) and 450 asymptomatic controls were further investigated. MAIN OUTCOME MEASURES: Drug use and symptoms reported by individuals found to have asthma or chronic obstructive pulmonary disease (COPD). RESULTS: Inhaled beta 2 agonists and inhaled steroids were used more often by individuals with asthma and COPD in Jämtland. However, regular use was more common in Gävleborg. Most of the asthmatics did not use any medication in spite of the fact that symptoms were commonly reported. The drug combinations most often used were inhaled beta 2 agonists alone or in combination with inhaled steroids. There were only minor differences in the prevalence of symptoms reported by individuals with asthma treated in different ways. CONCLUSION: Differences in the way anti-asthma drugs were used contributed to the observed difference in the sales of drugs. However, this difference was mainly caused by differences in the prevalence of asthma. The goals of asthma management plans were fulfilled only in a minority of patients despite the sales of asthma drugs being high.

Adolescent↗
PubMed1995

Thyroid hormone regulation of myosin heavy chain isoform composition in young and old rats, with special reference to IIX myosin.

The effects of 4 weeks of thyroid hormone (3,5,3'-triiodothyronine, T3) treatment on the myosin heavy chain (MHC) composition were compared in the slow-twitch soleus and the fast-twitch extensor digitorum longus (EDL) muscles from young (3-6 months) and old (20-24 months) male albino rats. Four MHC isoforms were separated on silver-stained 6% sodium dodecyl sulphate polyacrylamide gel electrophoresis. According to immunoblotting experiments with specific MHC monoclonal antibodies, the four MHCs corresponded to types I, IIB, IIX and IIA. In the soleus, the type I MHC content was higher in the old than in the young animals, and the type IIA content lower. Type IIX myosin was observed in some young control soleus, but not in old ones. After T3 treatment, the content of type I MHC decreased substantially in both young and old animals and that of type IIA increased. After T3 treatment, type IIX myosin was observed in both young and old animals, with a slightly higher IIX myosin content in old age, but the age-related difference in the contents of types I and IIA was diminished. In EDL, the type IIX MHC content was significantly higher in the old animals, at the expense of a lower content of type IIB MHC. MHC composition was not affected significantly by T3 treatment in EDL, either in young or old animals. In conclusion, an age-related motor unit transformation is observed in both the slow-twitch soleus and the fast-twitch EDL and the capacity for MHC isoform switching in response to T3 treatment is not impaired in old age.

Aging↗
PubMed1995

Effects of age on sarcoplasmic reticulum properties and histochemical composition of fast- and slow-twitch rat muscles.

Calcium release activity of sarcoplasmic reticulum and enzyme-histochemical properties were investigated in extensor digitorum longus (e.d.l.) and soleus muscles in young (4 months and old (24 months) male rats. With age, the caffeine threshold concentration for calcium release from the sarcoplasmic reticulum of soleus skinned muscle fibres showed only minor modifications. On the other hand, in e.d.l. skinned muscle fibres, the caffeine threshold concentration decreased significantly (P < 0.05). The histochemical fibre type composition changed with age both in soleus and in e.d.l. muscles, showing a common transformation toward a more oxidative histochemical profile. In fact, in aged soleus, a significant (P < 0.05) increase was observed of type 1 fibres to represent almost the totality of the muscle fibres (more than 98%), while types 2C and 2A were reduced in proportion. In aged e.d.l. the percentage of type 1 (P < 0.05), 2A and 2X (a recently identified fourth component of the fast-twitch muscle types) fibres increased, with a reduction of type 2B (P < 0.01) fibres. The present results suggest that the changes in contractile properties of aged muscles may be related to the changes not only in fibre composition but also in the mechanism of calcium release from sarcoplasmic reticulum.

Aging↗
PubMed1995

Chemical characterization of the ester-linked 3-hydroxy fatty acyl-containing lipids in Mycobacterium tuberculosis.

In a previous study (S. Alugupalli, F. Portaels, and L. Larsson, J. Bacteriol. 176:2962-2969, 1994), we reported the occurrence of 21 3-hydroxy fatty acids (3-OH-FAs) in the methanolysis products of different mycobacterial species. The present study was undertaken in order to chemically characterize the ester-linked complex native forms of these acids in Mycobacterium tuberculosis. Three 3-OH-FA-containing lipids were purified by chromatography and analyzed by one- and two-dimensional nuclear magnetic resonance spectroscopy, by fast atom bombardment-mass spectrometry, and by various conventional chemical analysis techniques. 3-OH-2,4,6-trimethyl-FAs were found in 2,3-diacyl trehalose and 2,3,6,6'-tetra-acyl-2'-sulfate trehalose (sulfatide I), two specific glycolipids of the tubercle bacillus, explaining the specific occurrence of these fatty acids in the methanolysis products of virulent strains of M. tuberculosis. Straight-chain 3-OH-FAs were localized in phosphatidyl ethanolamine but not in the other phospholipids, suggesting a possible role of this class of phospholipids in the metabolism of fatty acids in actinomycetes.

Chromatography↗
PubMed1995

Cervical lymphadenitis caused by a fastidious mycobacterium closely related to Mycobacterium genavense in an apparently immunocompetent woman: diagnosis by culture-free microbiological methods.

Fastidious mycobacteria usually infect immunocompromised hosts (human immunodeficiency virus-infected or otherwise immunosuppressed patients). We here describe severe lymphadenitis, caused by a fastidious mycobacterium closely related to Mycobacterium genavense, in an apparently immunocompetent woman, whose brother had died from an unidentified mycobacterial infection in 1969. A variety of techniques, including inoculation of nude mice, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology, were used to characterize this mycobacterium. All attempts to culture the etiological agent on many different media failed. The organism multiplied only in congenitally athymic nude mice. Although phenotypically similar to M. genavense, the mycobacterium differs from M. genavense by three nucleotides of the 16S rRNA gene sequence. Various antimycobacterial drugs were administered, including gamma interferon, but multiple relapses occurred. Finally, therapy with a combined regimen of clarithromycin, clofazimine, rifabutin, and ethambutol was curative. To our knowledge, this is the first report of lymphadenitis in an apparently immunocompetent patient, caused by a noncultivable Mycobacterium sp. closely related to M. genavense. This study emphasizes the importance of employing a variety of diagnostic approaches such as the inoculation of laboratory animals, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology to characterize novel microorganisms that cannot be cultured in vitro.

Adenosine Triphosphate↗
PubMed1995

Incidence of asthma in Swedish teenagers: relation to sex and smoking habits.

BACKGROUND: The prevalence of asthma and the use of asthma drugs is increasing worldwide. Studies of the incidence of asthma are few but are of interest in finding factors associated with onset of the disease. A study was performed to estimate the incidence of asthma and its relation to sex and to tobacco smoking between the ages of 16 and 19 years, and to compare the incidence of asthma with the proportion of individuals receiving a prescription of an asthma drug for the first time during one year. METHODS: A questionnaire was sent in 1990 to all 3627 individuals born in 1974 living in the county of Jämtland and Gästrikland, the southern part of the county of Gävleborg in central Sweden. Individuals reporting airways disease or obstructive symptoms were investigated with a further interview and lung function tests. The cross sectional questionnaire study was repeated in 1993. The incidence of asthma was calculated in the 2308 individuals who answered the questionnaire in both surveys and who were found not to have asthma in 1990. RESULTS: The yearly incidence of asthma defined from self reported disease, physician diagnosed asthma, drug use, or asthma associated symptoms was between 0.8% and 1.3%, depending on the criteria used. All criteria used resulted in a higher incidence in female subjects. Female sex was a risk factor for asthma when standardised for smoking, and smoking was also a risk factor for asthma when standardised for sex to all but two of the criteria used. In all the criteria the increased risk of asthma combined with smoking was greater in female subjects. CONCLUSION: The yearly incidence of asthma was about 1% between the ages of 16 and 19 years. Smoking and female sex were found to be risk factors for asthma. The incidence of asthma was close to the incidence of new drug use for asthma.

Adolescent↗
PubMed1995

Serum osteocalcin and bone and liver alkaline phosphatase isoforms in healthy children and adolescents.

We report reference values for osteocalcin and bone and liver alkaline phosphatase (ALP) isoforms in serum from 114 healthy children and adolescents, age 7-16 y. The bone and liver ALP isoforms were measured by high performance liquid chromatography (HPLC). Six ALP isoforms were separated and quantified in all samples: one bone/intestinal (B/I), two bone (B1 and B2), and three liver ALP isoforms (L1, L2, and L3). It is especially important to make distinctions between ages and gender during puberty in the interpretation of biochemical markers of bone. We observed that girls reached adult levels for osteocalcin, total ALP, and bone ALP isoforms, B/I, B1, and B2, earlier than boys. Girls in the oldest age group (15-16 y) and in the pubertal stage groups IV-V, reached higher levels than boys for the calculated ratio B1/B2 due to a more rapid decline of B2 compared with B1. This observation might indicate that B2, to a higher extent than the B1 isoform, represent a more mature expression of osteoblast differentiation during matrix mineralization in growing bone. Serial measurements of these new bone ALP isoforms could provide new insights into bone and mineral metabolism.

Adolescent↗
PubMed1995

Biochemical markers of renal disease in primary Sjögren's syndrome.

Primary Sjögren's syndrome (SS) is characterized by an inflammatory process in the salivary and lacrimal glands, but the kidneys may also be involved. Renal tubular functions were studied in 27 patients with SS, all females, age 37-78. Both SS-patients with and without known distal renal tubular acidosis (dRTA) were included, dRTA was found in 18/27 (67%), impaired urine concentrating ability in 13/27 (48%). Hypocitraturia was identified in 20/27 (74%) and reduced tubular reabsorption of phosphate (TRP%) in 18/27 (67%). Tubular proteinuria (alpha 1-mikroglobulin) was present in 11/24 (46%), and tubular enzymuria (NAG) in 7/24 (29%). Hypocitraturia and/or dRTA were found in all patients with any kind of abnormal renal tubular function test. All except one of the patients with dRTA not treated with sodium bicarbonate had hypocitraturia. We conclude that distal tubular dysfunction was common in our SS-patients, but a concommitant proximal dysfunction was also seen. Determination of urinary citrate represents a valuable test for detection of renal disease in SS.

Acetylglucosaminidase↗
PubMed1994

Effects of thyroid hormone on fast- and slow-twitch skeletal muscles in young and old rats.

1. The effects of 4 weeks of thyroid hormone treatment on contractile, enzyme-histochemical and morphometric properties and on the myosin isoform composition were compared in the slow-twitch soleus and the fast-twitch extensor digitorum longus (EDL) muscle in young (3-6 months) and old (20-24 months) male rats. 2. In the soleus of untreated controls, contraction and half-relaxation times of the isometric twitch increased by 19-32% with age. The change in contractile properties was paralleled by an age-related increase in the proportions of type I fibres and type I myosin heavy chain (MHC) and slow myosin light chain (MLC) isoforms. 3. In the EDL of controls, contraction and half-relaxation times were significantly prolonged (21-38%) in the post-tetanus twitch in the old animals. No significant age-related changes were observed in enzyme-histochemical fibre-type proportions, although the number of fibres expressing both type IIA and IIB MHCs and of fibres expressing slow MLC isoforms was increased in the old animals. 4. Serum 3,5,3',5'-tetraiodothyronine (T4) levels were lower (34%) in the old animals, but the primary byproduct of T4, 3,5,3'-triiodothyronine (T3), did not differ between young and old animals. 5. The effects of 4 weeks of thyroid hormone treatment were highly muscle specific, and were more pronounced in soleus than in EDL, irrespective of animal age. In the soleus, this treatment shortened the contraction and half-relaxation times by 35-57% and decreased the number of type I fibres by 66-77% in both young and old animals. In EDL, thyroid hormone treatment significantly shortened the contraction time by 24%, but the change was restricted to the old animals. 6. In conclusion, the ability of skeletal muscle to respond to thyroid hormone treatment was not impaired in old age and the age-related changes in speed of contraction and enzyme-histochemical properties and myosin isoform compositions were diminished after thyroid hormone treatment in both the soleus and EDL.

Aging↗