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Biomedical subjects

L Larsson

Publications and source records attributed to L Larsson.

At least 181 records · Page 10Linked to original sources
PubMed1993

Detection of 2-eicosanol by gas chromatography-mass spectrometry in sputa from patients with pulmonary mycobacterial infections.

A total of 96 sputum specimens from patients with suspected or known mycobacterial and nonmycobacterial pulmonary infections were analyzed by gas chromatography-mass spectrometry for the presence of 2-eicosanol. This secondary alcohol was detected in all of the 25 sputum specimens culture positive for Mycobacterium tuberculosis, in 7 of the 9 sputum specimens culture positive for M. avium complex, and in all 3 of the studied sputum specimens associated with M. malmoense. The alcohol was not detected in any of the 45 culture-negative sputum specimens or in 14 sputum specimens culture positive for Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae, and Streptococcus pneumoniae. The ratio of tuberculostearic acid to 2-eicosanol was much lower in sputum samples culture positive for mycobacteria than in the corresponding in vitro-grown cultures. The present findings indicate that 2-eicosanol may be useful as a chemical marker for rapid diagnosis of pulmonary infections caused by the M. avium complex, M. malmoense, and M. tuberculosis.

Biomarkers↗
PubMed1993

Differences in utilization of asthma drugs between two neighbouring Swedish provinces: relation to symptom reporting.

Utilization of anti-asthma drugs is rapidly increasing and varies markedly between counties in Sweden. In 1989, the sales in the county of Gävleborg were less than 60% of those in neighbouring Jämtland. In order to study the possible reasons for--and effects of--this difference, an epidemiological survey was started in 1989, the first part of which is reported here. A questionnaire was sent to all 16 yr olds, and to a random sample of 30-39 and 60-69 yr olds, in the two counties. A total of 12,500 questionnaires were distributed. Overall response rate was 90%. A total of 7.2% in Jämtland and 5.8% in Gävleborg (p < 0.01) reported that they had had asthma at some time. A similar significant difference between the counties was also present in response to questions on attacks of shortness of breath, wheezing and self-reported diagnosis of asthma, as well as on use of anti-asthma drugs. There were no statistically significant differences between the counties in positive answers to questions concerning history and symptoms of chronic bronchitis; approximately 5% in the oldest age group. The findings support earlier results indicating a high asthma prevalence in northern Sweden. Contrary to reports from other countries, the prevalence was higher in the colder and less urbanised of the two provinces. We conclude that the differences in drug sales between the counties reflect a difference in prevalence of asthmatic symptoms.

Adolescent↗
PubMed1992

Determination of alkaline phosphatase isoenzymes in serum by high-performance liquid chromatography with post-column reaction detection.

A weak anion-exchange high-performance liquid chromatographic procedure with post-column reaction detection for simultaneous determination of alkaline phosphatase (EC 3.1.3.1, ALP) isoenzymes is described. We identified six peaks with ALP isoenzyme activity in normal serum. The peaks were, in order of elution, one intestinal/bone, two bone and three liver ALP isoenzymes. This new assay with automatic injection, on-line post-column reaction detection and powerful integration data system could be of significant value in the routine clinical biochemistry laboratory. The advantages include improved sensitivity and selectivity over previous methods for the determination of ALP isoenzymes.

Alkaline Phosphatase↗
PubMed1992

Evidence for Randall's plaques to be the origin of primary renal stones.

Lithofibrin, a non-protein organic component of renal calculi was found in renal papillas with the aid of stereo microscopy under UV illumination. Scanning electron microscopy revealed fibers of which one had a clump containing calcium on the top. The findings support the theory of Randall, that the origin of primary renal calculi is to be found in the kidney, not in the urine.

Humans↗
PubMed1992

The effects of a single evening dose of alkaline citrate on urine composition and calcium stone formation.

The effects on urine composition and pH of a single evening dose of alkaline potassium sodium citrate were studied in healthy subjects and recurrent calcium oxalate stone formers. This treatment resulted in a prompt and significantly increased urinary pH with a duration until 10 a.m. the next day and a reduced risk of calcium oxalate crystallization between 10 p.m. and 10 a.m. In a retrospective study alkaline citrate was given in a single evening dose of 3.75 or 5 gm. to 55 patients with calcium oxalate stone disease and a total dose of 5.0 or 7.5 gm. was administered 2 or 3 times daily in 17 patients. The mean plus or minus standard deviation for duration of treatment was 3.5 +/- 1.7 years. Significantly reduced stone formation was recorded only in those on the evening dose regimen, which was associated with significant improvement of urine composition. Patients who continued to form new stones or who had growth of residual stones despite treatment also had improved urine composition but the calcium excretion and the calcium/citrate quotient remained elevated. In 4 patients with new stone formation calcium phosphate was the major component and calcium excretion was high but the concomitant increased citrate excretion resulted in a calcium/citrate quotient that was only slightly elevated. In patients forming calcium oxalate stones the only abnormality was a high calcium/citrate quotient. Because of favorable biochemical and clinical effects as well as good patient compliance with a single evening dose of alkaline citrate, this regimen appears to be an attractive alternative for long-term prevention of recurrent calcium stone formation.

Adult↗
PubMed1992

Evaluation of polymerase chain reaction, tuberculostearic acid analysis, and direct microscopy for the detection of Mycobacterium tuberculosis in sputum.

Tuberculosis remains a major global cause of morbidity and mortality. There is an urgent need for improved bacteriologic diagnosis of Mycobacterium tuberculosis infection. Three methods for rapid identification of M. tuberculosis in sputum samples (direct microscopy, gas chromatography-mass spectrometry [GC-MS], and polymerase chain reaction [PCR]), were compared with culture on Lowenstein-Jensen medium. Growth of M. tuberculosis was observed in 38 of 145 sputum samples. Detection of acid-fast bacilli by direct microscopy gave a sensitivity of 66% and a specificity of 100%. Detection of tuberculostearic acid by GC-MS gave a sensitivity of 55% and a specificity of 87%. Amplification by PCR of a fragment of the insertion sequence IS6110 gave a sensitivity of 95% and a specificity of 93% compared with culture and a corrected specificity of 99% compared with both culture and clinical data. This study indicates that PCR can be adapted for clinical use and is the method of choice for rapid diagnosis of pulmonary tuberculosis.

Base Sequence↗
PubMed1992

Secondary fatty alcohols of Mycobacterium xenopi.

Secondary alcohols of Mycobacterium xenopi were studied by gas chromatography and gas chromatography-mass spectrometry. Mycobacterial cells were hydrolysed and the liberated alcohols separated by extraction and analysed both underivatized and as trimethylsilyl, methyl ether- and pentafluorobenzoyl derivatives. Seven straight-chain secondary alcohols containing from 18 to 24 carbon atoms and two branched-chain secondary alcohols with 21 and 23 carbon atoms were present in all of the studied strains.

Chromatography, Gas↗
PubMed1992

Is the motor unit uniform?

Single motor units in the fast-twitch tibialis anterior muscle were functionally isolated by stimulation of microdissected ventral root filaments. The muscle fibres of 35 fast-twitch single motor units (motor unit fibres), 18 units from 3 to 6-month-old and 17 units from 20 to 24-month-old male rats, were identified by glycogen depletion. Measurements were made of staining intensities for intermyofibrillar succinate dehydrogenase, using microphotometric techniques, and of cross-sectional areas of the motor unit fibres. The average coefficients of variation for succinate dehydrogenase activity of the muscle fibres within each unit, between the different units and for repeated measurements of the same fibre in 10 consecutive cross-sections stained on different glasses were 26, 72 and 14%, respectively. The average coefficients of variation for cross-sectional fibre areas within each unit, between the different units and for repeated measurements were 21, 53 and 7%, respectively. Further, the succinate dehydrogenase activity of muscle fibres within the motor unit differed significantly depending on the position of the fibre along the superficial-deep axis of the muscle. The average succinate dehydrogenase activity in the 35 motor units was 21% lower (P less than 0.001) in the superficial as compared with the deep motor unit fibres. In order to eliminate the influence of altered motoneurone properties related to a transformation process or an age-related motoneurone dysfunction as indicated by a non-homogeneous myosin heavy chain composition in motor unit fibres, cross-sectional fibre areas and enzyme activities were also compared in motor units with a uniform myosin heavy chain composition in young animals. However, the same regional differences were observed in these 16 units as when all the 35 units were pooled together. Thus, in conformity with previous reports, the variability in enzyme activities within single motor unit fibres is small but too large for a motor unit homogeneity to be accepted. In addition, the present results demonstrate that the systematic differences in succinate dehydrogenase activities of motor unit fibres along the superficial-deep axis of the tibialis anterior muscle represent a biological rather than a methodological phenomenon.

Adenosine Triphosphate↗
PubMed1992

A technique for studies of the contractile apparatus in single human muscle fibre segments obtained by percutaneous biopsy.

Human muscle samples were obtained with the percutaneous biopsy technique. The samples were membrane-hyperpermeabilized (skinned) using a chemical or freeze-drying technique. Short single fibre segments were dissected from the sample, transferred to an experimental chamber, connected to a force transducer and manipulator, and exposed to temperature-controlled solutions. The force generating-capacity, the sensitivity of the contractile apparatus to calcium and the caffeine threshold for calcium release from the sarcoplasmic reticulum could be studied in the short muscle fibre segments obtained from man with the percutaneous muscle biopsy technique. The average length of the fibre segments between the connectors was 0.44 +/- 0.21 mm. Thus, detailed studies of the contractile machinery can be made on human skinned muscle fibres with only minimal discomfort to the patient or subject during biopsy, which should be useful in studies of neuromuscular disease, muscle plasticity or in applied physiology.

Biomechanical Phenomena↗
PubMed1992

Application of gas chromatography-mass spectrometry for rapid detection of Mycobacterium xenopi in drinking water.

Gas chromatography-mass spectrometry (GC-MS) was used to detect 2-docosanol, a secondary alcohol characteristic of Mycobacterium xenopi, in 7 of 10 analyzed drinking water samples culture positive for that species. GC-MS was also used to detect tuberculostearic acid. Both of these chemical markers were analyzed as halogenated derivatives in the negative-ion-chemical-ionization mode. The numbers of CFU of M. xenopi were lowest in the three GC-MS-negative samples. The described GC-MS method is useful for the rapid detection of M. xenopi in drinking water.

Czechoslovakia↗
PubMed1992

Lipid A in Helicobacter pylori.

Free lipid A of Helicobacter pylori was characterized with regard to chemical composition, reactivity with anti-lipid A antibodies, and activity in a Limulus lysate assay. The predominant fatty acids of H. pylori lipid A were 3-OH-18:0, 18:0, 3-OH-16:0, 16:0, and 14:0. Hexosamine was present in amounts similar to those in Campylobacter jejuni or Salmonella typhimurium lipid A. The lipopolysaccharide of H. pylori contained 2-keto-3-deoxyoctonic acid, a common constituent of enterobacterial and C. jejuni lipopolysaccharides. In the enzyme-linked immunosorbent assay, the doses of lipid A required to inhibit anti-lipid A by 50% (EI50 values) by absorption of the immune (rabbit) serum were 7.9, 1.2, and 1.4 micrograms of O-deacylated lipid A's from H. pylori, C. jejuni, and S. typhimurium per ml, respectively. The lower reactivity of H. pylori lipid A compared with those of the other two lipid A preparations (as shown by the higher EI50 value) was underscored by the use of a murine monoclonal anti-lipid A antibody in the inhibition assay. An EI50 value was not obtained at the concentrations tested for H. pylori lipid A; the corresponding figures for C. jejuni and S. typhimurium lipid A's were 13 and 14 micrograms/ml, respectively. No inhibition was obtained with H. pylori lipopolysaccharide, which showed a low-molecular-weight profile on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The activity of H. pylori lipid A in the Limulus assay was approximately 71 and 650 times lower than those of C. jejuni and S. typhimurium lipid A's, respectively. These findings suggest that lipid A is an integral part of the outer cell wall of H. pylori. The lower reactivity of H. pylori lipid A with anti-lipid A antibodies and in the Limulus assay compared with that of C. jejuni or S. typhimurium lipid A may be explained by a different composition of the fatty acids, especially the 3-hydroxy fatty acids, and a possible deviating phosphorylation pattern.

Animals↗
PubMed1992

Characterization and distribution of Pasteurella species recovered from infected humans.

During a 3-year period, all Pasteurella strains recovered at the Clinical Microbiological Laboratory, Lund, Sweden, were studied biochemically with respect to their relationship to the recently described taxa of this genus. Of 159 strains recovered from 146 infected humans, 95 were identified as Pasteurella multocida subsp. multocida, 21 as Pasteurella multocida subsp. septica, 28 as Pasteurella canis, 10 as Pasteurella stomatis, and 5 as Pasteurella dagmatis. The homology within and between the Pasteurella species regarding cellular fatty acids and enzymatic activities was also studied. Strains of the different Pasteurella species were indistinguishable from each other regarding fatty acid composition; all strains contained major amounts of C14:0, C16:1, C16:0, and 3-OH-C14:0 acids and minor amounts of C18:2, C18:1, and C18:0 acids. Neither did the enzymatic activities distinguish between strains belonging to different species. In addition, of 56 strains examined, toxin production was demonstrated only in 1 strain each of P. multocida subsp. multocida and P. canis. Except for one severe case of necrotizing cellulitis involving P. dagmatis, P. multocida subsp. multocida or P. multocida subsp. septica was recovered in the more serious cases of infection. Except for P. canis, which in all cases was associated with dog bites, most Pasteurella strains were recovered in cases of infection associated with cat bites or scratches. Pasteurella strains occurred in four infected patients without evident connections with animals.

Animals↗
PubMed1992

Neurogenic effects on the palatopharyngeal muscle in patients with obstructive sleep apnoea: a muscle biopsy study.

Muscle biopsies from the palatopharyngeal muscle of eight patients with obstructive sleep apnoea were performed during uvulopalatopharyngoplasty. Control biopsies were performed during tonsillectomy in seven control patients with no history of symptoms suggesting obstructive sleep apnoea. The diagnosis was based on the patient's history and a whole night recording of arterial oxygen saturation and respiration movements. The mean number of oxygen desaturations > or = 4% per sleeping hour was 39 (range 7-80) in patients with obstructive sleep apnoea. In the control patients the occurrence of muscle fibre type and size relation between type I and type II fibres were comparable to what is found in the quadriceps femoris muscle, but the mean size of the fibres was < 25% of what is found in limb muscles. All biopsies from patients with obstructive sleep apnoea showed abnormalities. Atrophy with a fascicular distribution, increased number of angulated atrophic fibres, a twin or multiple peak distribution of the fibre size spectra, and an abnormal distribution of fibre types in many muscle fascicles corresponding to "type grouping" all points to a neurogenic alteration. This neurogenic lesion may be a primary phenomenon or secondary to the trauma of repetitive and prolonged stretching of the pharyngeal structures during apnoeas. A disturbance of the function of the dilating muscles of the upper airway may be important in causing the abnormal airway collapse seen in obstructive sleep apnoea.

Adult↗
PubMed1992

Clinical significance of phosphate in calcium oxalate renal stones.

We analysed calcium, magnesium, oxalate, citrate, urate and creatinine in urine and calculated risk factors in patients who had formed stones composed of calcium oxalate, and calcium phosphate, alone or as a mixture. Patients producing pure calcium oxalate stones (less than 0.1% phosphate) had a higher oxalate, and lower calcium excretion than stone-free subjects and patients forming other stone types. In contrast, patients producing calcium oxalate stones containing phosphate, even in trace amounts (greater than 0.1%) had no increase in oxalate excretion, but a higher calcium excretion than stone-free subjects. We could not correlate any computed variable (e.g. AP(CaOx) index) to stone composition. We conclude that pure CaOx stones may be the result of a high oxalate excretion, and that other calcium containing stones may have another and probably more complex aetiology, including primary precipitation of calcium phosphates.

Calcium Oxalate↗
PubMed1992

Identification of murine thymocyte populations capable of extensive proliferation in serially passaged thymic organ cultures.

Using the approach of titrating precursor cells into mouse thymus organ cultures and serial passage, we have sought to compare the proliferative capacities of cells derived from adult and embryonic thymus and related haemopoietic tissues. We find that cells derived from the liver and thymus of day 14 embryos are capable of extensive proliferation in such cultures (surviving for at least 12 weeks) whereas cells derived from adult sources (blood and thymus) display a much more restricted lifespan and potential for division. Analysis of sequentially passaged thymic lobes shows that cells lacking CD4 and CD8 (CD4- and CD8-) and a subset of single CD8 positives are selectively expanded in these cultures. A preliminary study of the CD4-CD8- populations in these lobes suggest that these include cells expressing surface CD3 (in association with either TCR alpha beta or TCR gamma delta) and a subset of CD4-CD8-CD3-. These findings suggest that sequential passage of thymocytes in organ culture may be a useful alternative strategy for characterising cells with high proliferative potential, resident in the thymus and also for probing their lineage relationships.

Animals↗
PubMed1992

Quality assurance in urine analysis.

An Australian quality control (QC) system was tested on its ability to detect analytical errors in calcium, creatinine, oxalate, phosphate and uric acid determinations in urine. This QC system revealed that our methods for calcium and urate worked well. The oxalate values were systematically higher than the assigned values and the random error was too high. Phosphate and creatinine had a marked positive deviation in the higher range of concentration but agreed better in the medium and lower ranges. The findings emphasize the need for external QC systems in urine analysis. We also discuss specific problems with urine QC compared with conventional QC for serum, the theoretical basis of creatinine-corrected urinary analytes and criteria for rejection and warning limits. We conclude that QC of urine analysis is as important as that of serum and that such programs should be used in concordance with serum QC programs.

Australia↗
PubMed1991

Pulmonary disease caused by Mycobacterium malmoense. Comments on the possible origin of infection and methods for laboratory diagnosis.

Mycobacterium malmoense was isolated from sputum and gastric lavage from a 68-year-old man with gastric adenocarcinoma. The patient meets the criteria for diagnosis of pulmonary mycobacteriosis. The cultural, physiological and biochemical properties of the isolates were compared with other slowly growing mycobacterial species. Fatty and mycolic acid analyses revealed the presence of 2-methyleicosanoic and 2,4,6-trimethyltetracosanoic acids and alpha-, alpha'-and ketomycolates, all regarded as typical for M. malmoense. The possible origin of M. malmoense infections and methods for laboratory diagnosis are discussed. This is the first case of documented infection due to this organism in Belgium.

Adenocarcinoma↗