Biomedical subjects

L Larsson

Publications and source records attributed to L Larsson.

At least 19 recordsLinked to original sources

PubMed2000

New and simple procedure for the determination of muramic acid in chemically complex environments by gas chromatography-ion trap tandem mass spectrometry.

A gas chromatographic-ion trap tandem mass spectrometric method was developed for the quantification of muramic acid, a marker of bacterial peptidoglycan, in environmental and clinical specimens. Samples (bacteria, house dust and urine) were heated in methanolic hydrochloric acid overnight and extracted with hexane for removal of hydrophobic compounds. The aqueous phase was evaporated and heated in acetic anhydride and pyridine after which the product, the acetate derivative, was washed with dilute hydrochloric acid and water. The described method is both rapid and simple to apply, and produces a stable derivative. It should become widely used for measuring peptidoglycan in chemically complex environments.

Acetic Anhydrides↗

PubMed2000

Serum isoforms of bone alkaline phosphatase increase during physical exercise in women.

Physical activity is an important factor for maintaining and probably increasing bone mass in humans. However, the mechanism by which this takes place is not completely understood. The purpose of this study was to examine the influence of physical exercise on serum alkaline phosphatase (ALP) and in particular, the bone isoforms of ALP. Six ALP isoforms were quantified by high-performance liquid chromatography: three bone (B/I, B1, and B2), and three liver ALP isoforms. In addition, serum calcium, parathyroid hormone (PTH), and other markers of bone formation and degradation, as measured by osteocalcin and cross-linked carboxyterminal telopeptide of type I collagen (ICTP), were analyzed. The study groups comprised 15 women, 8 postmenopausal (range 51-62 years) and 7 near age of peak bone mass (range 21-27 years). When the postmenopausal women exercised on an ergometer cycle until exhaustion we found significant increases in serum of bone ALP isoforms B1 and B2, and phosphate, even considering the hemoconcentration that occurred during the exercise. When the young women jogged in a moderate tempo for 40-40 minutes the levels of serum B2 and PTH increased. All changes turned towards baseline within 20 minutes after exercise. In conclusion, exercise increased serum ALP bone isoforms B1 and B2, and their responses were differentiated. As B1 and B2 are known to represent specific bone compartments, cortical and trabecular bone, the present findings may indicate different effects on bone of weight- and nonweight-bearing exercise.

Adult↗

PubMed2000

Microwaving for double indirect immunofluorescence with primary antibodies from the same species and for staining of mouse tissues with mouse monoclonal antibodies.

Many methods have been devised for double immunocytochemical staining. We now describe that moderate microwaving does not elute antibodies, but prevents their reactions with subsequently applied reagents. Thus, microwaving performed in between the first and second staining cycles permits double indirect immunofluorescence staining with antibodies raised in the same species. Moreover, microwaving also inhibits reactions with endogenous immunoglobulins present in extracellular compartments. This substantially reduces background in indirect immunostaining of mouse tissues with mouse monoclonal antibodies.

Animals↗

PubMed2000

Candida tropicalis vertebral osteomyelitis complicating epidural catheterisation with disease paralleled by elevated D-arabinitol/L-arabinitol ratios.

Deep-seated Candida infections are challenging to diagnose by noninvasive means, and new modalities are needed to improve the yield of such investigations. Reported here is a case of Candida tropicalis vertebral osteomyelitis complicating epidural catheterisation in a diabetic patient with complicated abdominal sepsis. The diagnosis was supported by detection of increased D-arabinitol/L-arabinitol ratios in urine samples, and failure of medical management was indicated by elevated D-arabinitol/L-arabinitol ratios, which later decreased to baseline with successful surgical debridement and prolonged antifungal therapy.

Aged↗

PubMed2000

Actomyosin interactions in a novel single muscle fiber in vitro motility assay.

A novel in vitro motility assay has been developed to study the actomyosin interaction, in which the molecular motor protein myosin has been extracted and immobilized directly from 2-4 mm single rat skeletal muscle fiber segments. This method study was carried out to investigate: (1) the amount of myofibrillar proteins extracted from the fiber segment; (2) the effects of temperature on the speed at which actin is propelled by fast and slow myosin; and (3) the effects of myosin isoform expression on motility speed. Approximately 80% of the myosin and myosin-associated proteins were extracted from the fiber segments. while no significant extraction was shown of the thin filament proteins. Fluorescently labeled actin filaments moved with constant speed in a bi-directional motion over the high-density myosin region in the experimental chamber, and motility speed was highly dependent on the myosin heavy chain (MyHC) isoform extracted. At 25 degrees C, significant (P < 0.001) differences in motility speed were obtained between type I (1.31 +/- 0.23 microm/s, n = 11) and IIxb (5.81 +/- 0.35 microm/s, n = 6), or llb (6.07 +/- 0.33 microm/s, n = 8) MyHC isoforms. The motility speed and maximum velocity of unloaded shortening (V0) in single fibers were well correlated, indicating that filament speed is a good molecular analogue to contractile speed at the fiber level. The effects of temperature on filament motility speed were analyzed from 10 to 35 degrees C. The Q10 values, calculated in the 10-25 degrees C temperature range, differed between slow (4.20) and fast (2.38) myosin. In conclusion, this in vitro motility assay offers a unique possibility to compare the regulatory and modulatory influence of myosin isoforms and thin filament proteins on shortening velocity, at the cellular and molecular level in the same muscle fiber.

Actins↗

PubMed2000

Characterization and variability of endotoxin and 3-hydroxy fatty acids in an office building during a particle intervention study.

Air and dust samples were collected on two floors of an office building during a double-blind particle intervention study to examine spatial and temporal variability of airborne endotoxin over a period of weeks, and to characterize endotoxin activity and lipopolysaccharide (LPS) content in carpet and chair dust. Air samples were collected on multiple days within and across weeks. Dust samples were collected from carpets and chairs one day per week for three weeks. Endotoxin was measured using a Limulus assay. Dust samples were analyzed for LPS by determination of 3-hydroxy fatty acids (3-OHFAs) using gas chromatography-mass spectrometry. The geometric mean (geometric standard deviation) for 96 indoor air samples was 0.24 (1.6) EU/m3. Significant within-floor spatial variation of airborne endotoxin was found (P < 0.0001, n = 80). Temporal variability of airborne endotoxin was not significant across weeks. Mean (+/- SD) endotoxin levels in carpet dust (59 +/- 9.3 EU/mg dust, n = 12) and in chair dust (38 +/- 7.7 EU/mg dust, n = 10) were significantly different (P < 0.001). Carbon chain length-dependent differences in 3-OHFA levels by dust source and floor were found. Enhanced air filtration did not significantly affect airborne endotoxin (P = 0.62); however, total dust mass and total endotoxin in carpet dust samples increased significantly after enhanced surface cleaning (P < 0.01). These findings suggest that spatial variability, dust source, and surface cleaning may influence building occupant exposures to endotoxin.

Air Pollution, Indoor↗

PubMed2000

Determination of microbial colonisation in water-damaged buildings using chemical marker analysis by gas chromatography-mass spectrometry.

Gas chromatography-mass spectrometry was used to determine the microbial contents of building materials subjected to water damage in a laboratory experiment and of materials collected from houses affected by water during the flood in Klodzko in south-western Poland, July 1997. The samples were examined for 3-hydroxy fatty acids, markers of bacterial endotoxin, and ergosterol, marker of fungal biomass. The amounts of both 3-hydroxy fatty acids and ergosterol were higher in materials that had been exposed to water than in unexposed ones. All markers were stable in the building materials for at least 6 weeks at room temperature and could thus be used to reveal microbial contamination even when cultivation results for bacteria and fungi were negative. Direct measurement of 3-hydroxy fatty acids and ergosterol in human environments could be a useful method, e.g. in monitoring indoor air as regards presence of potentially harmful microorganisms and microbial constituents.

Air Pollution, Indoor↗

PubMed2000

Preliminary report on the results of the second phase of a round- robin endotoxin assay study using cotton dust.

In an on-going endotoxin assay study, a two-part interlaboratory endotoxin assay study has been completed. The purpose of the study was to compare the variation in assay results between different laboratories, and, if the variation was high, to see if a common protocol would reduce the variation. In both parts of the study, membrane filters laden with the same approximate amount and type of cotton dust were sent for analysis to laboratories that "routinely" perform endotoxin analyses. First, each of these laboratories performed the analysis using the methodology common to its laboratory. In the second part of the study, membrane filters with cotton dust were again sent to the same laboratories where the analyses were performed as before but with a common extraction protocol. The preliminary results from the first phase of the study have been collected and showed that intra-laboratory variations were small, but large and significant interlaboratory variation was observed. The results were reported elsewhere. The preliminary results from the second part of the study consisting of the data currently collected are presented here. Again, intra-laboratory variations were small, but, also again, large and significant inter-laboratory variation was observed. However, in this part of the study, the range between the highest and lowest average results was narrower than in the first part of the study. Influence of the assay kit type was examined. The variation within assay kit type was small but significant differences in results were observed between assay kit types. The findings suggest that endotoxin concentration in samples can be ranked within laboratories, but not necessarily between laboratories. However, some of the variation between laboratories has been reduced by a common extraction protocol which suggests the possibility of further standardization that may lead to better comparability between laboratories.

Air Pollution, Indoor↗

PubMed2000

Investigation of the concentration of bacteria and their cell envelope components in indoor air in two elementary schools.

Bacterial cell envelope components are widely distributed in airborne dust, where they act as inflammatory agents causing respiratory symptoms. Measurements of these agents and other environmental factors are assessed in two elementary schools in a southeastern city in the United States. Muramic acid (MA) was used as a marker for bacterial peptidoglycan (PG), and 3-hydroxy fatty acids (3-OH FAs) were used as markers for Gram-negative bacterial lipopolysaccharide (LPS). Culturable bacteria were collected using an Andersen sampler with three different culture media. In addition, temperature (T), relative humidity (RH), and CO2 were continuously monitored. Concentrations of airborne MA and 3-OH FAs were correlated with total suspended particulate (TSP) levels. Outdoor MA (mean = 0.78-1.15 ng/m3) and 3-OH FA levels (mean = 2.19-2.18 ng/m3) were similar at the two schools. Indoor concentrations of airborne MA and 3-OH FAs differed significantly between schools (MA: 1.44 vs. 2.84 ng/m3; 3-OH FAs: 2.96 vs. 4.57 ng/m3). Although indoor MA levels were low, they were significantly related to teachers' perception of the severity of indoor air quality (IAQ) problems in their classrooms. Concentrations of CO2 correlated significantly with all bacteria measurements. Because CO2 levels were related to the number of occupants and the ventilation rates, these findings are consistent with the hypothesis that the children and teachers are sources of bacterial contamination. Many culturable bacteria present in indoor air are opportunistic organisms that can be infectious for compromised individuals, while both culturable and nonculturable bacterial remnants act as environmental toxins for both healthy and compromised individuals. Measuring the "total bacteria load" would be most accurate in assessing the biotoxicity of indoor air. Chemical analysis of MA and 3-OH FAs, when coupled with the conventional culture method, provides complementary information for assessing biocontamination of indoor air.

Air Microbiology↗

PubMed2000

Acute quadriplegia and loss of muscle myosin in patients treated with nondepolarizing neuromuscular blocking agents and corticosteroids: mechanisms at the cellular and molecular levels.

OBJECTIVE: Long-term treatment with nondepolarizing neuromuscular blocking agents and corticosteroids in the intensive care unit is not benign, and an increasing number of patients with acute quadriplegic myopathy have been reported with increased use of these drugs. The purpose of this study was to investigate the mechanisms underlying acute quadriplegic myopathy. DESIGN: Percutaneous muscle biopsy samples were obtained, and electrophysiologic examinations were performed during the acute phase and during recovery in patients with acute quadriplegic myopathy. Regulation of muscle contraction and myofibrillar protein synthesis was studied using cell physiologic techniques, ultrasensitive electrophoresis, in situ hybridization, and histopathologic techniques. SETTING: All patients were seen in the intensive care unit of different university hospitals. PATIENTS: All patients were critically ill with sepsis. They had been given massive doses of corticosteroids in combination with variable doses of neuromuscular blocking agents. All patients developed paralysis of spinal nerve-innervated muscles. On the other hand, cranial nerve-innervated muscle and sensory and cognitive functions were well maintained after discontinuation of treatment with neuromuscular blocking agents. INTERVENTION: Muscle biopsy samples were obtained and electrophysiologic examinations were performed in all patients. MEASUREMENTS AND MAIN RESULTS: The major observations in patients with acute quadriplegic myopathy were, as follows: a) a general decrease in myofibrillar protein content; b) specific but highly variable partial or complete loss of myosin and myosin-associated proteins; c) very low thick-filament/thin-filament protein ratios; d) absence of myosin messenger RNA; and e) a dramatically impaired muscle cell force-generating capacity in the acute phase of acute quadriplegic myopathy. During clinical improvement, normal expression of myosin messenger RNAs, reexpression of thick-filament proteins, and increased specific tension were observed. CONCLUSIONS: Acute quadriplegic myopathy is associated with a specific decrease in thick-filament proteins related to an altered transcription rate. Although the decreased content of thick-filament proteins is important for prolonged muscle weakness, it is not the primary cause of muscle paralysis in the acute stage, during which impaired muscle membrane excitability probably plays a more significant role. Several factors contribute to this condition, but the action of corticosteroids seems to be the predominant one, along with potentiation by neuromuscular blocking agents, immobilization, and probably also concurrent sepsis.

Acute Disease↗

PubMed2000

A population-based study on motor performance and white matter lesions in older women.

OBJECTIVE: To investigate the relationship between motor performance and white matter lesions (WMLs) on computed tomography (CT) of the brain in older women. DESIGN: Cross-sectional study. SETTING: Population-based study in Göteborg, Sweden. PARTICIPANTS: A total of 248 women aged 70, 74, and 78 years. MEASUREMENTS: Motor performance was measured by a Postural-Locomotion-Manual (PLM) test using an optoelectronic technique. WMLs on CT scans were rated as no, mild, moderate, or severe. RESULTS: White matter lesions were associated with impaired mobility of the lower extremities, that is, prolonged locomotion phase in the PLM test. This association was also present after controlling for age, hypertension, coronary heart disease, stroke, diabetes mellitus, chronic bronchitis, intermittent claudication, and smoking. CONCLUSIONS: Cerebral white matter lesions may contribute to motor impairments in older adults.

Activities of Daily Living↗

PubMed2000

Urine D-arabinitol/L-arabinitol ratio in diagnosis of invasive candidiasis in newborn infants.

Infants treated in neonatal intensive care units suffer an increased risk for invasive candidiasis, but the diagnosis is sometimes difficult. D-arabinitol is a metabolite of most pathogenic Candida species. An elevated urine D-arabinitol/L-arabinitol (DA/LA) ratio is a sensitive sign of invasive candidiasis in children with cancer, but the method has not been previously evaluated for newborn infants. We therefore enrolled 117 infants in a neonatal intensive care unit, and 411 urine samples were obtained on filter paper. The DA/LA ratio was measured by gas chromatography-mass spectrometry. For 81 infants with no suspicion of superficial or invasive candidiasis, the urine DA/LA ratio was 2.7 +/- 0.7 (mean +/- standard deviation [SD]). The upper cutoff level was set at 4.8 (mean plus 3 SD). Of 22 infants with mucocutaneous candidiasis and not given systemic antifungal treatment, two had elevated DA/LA ratios, which normalized after removal of intravascular catheters. Eight other infants were given empiric antifungal treatment but had negative cultures; five of these had repeatedly elevated DA/LA ratios. Six infants with culture-positive invasive candidiasis all had one or more samples with elevated ratios. For seven infants, three with suspected and four with confirmed invasive candidiasis (for which follow-up samples were available), ratios normalized during antifungal treatment. In conclusion, urine DA/LA ratio determination is a rapid test and can be used for newborns. It is possibly more sensitive than fungal blood cultures in the diagnosis of invasive candidiasis and can also be used for monitoring the effect of antifungal treatment.

Candidiasis↗

PubMed2000

Effects of thyroid hormone receptor gene disruption on myosin isoform expression in mouse skeletal muscles.

Skeletal muscle is known to be a target for the active metabolite of thyroid hormone, i.e., 3,5,3'-triiodothyronine (T(3)). T(3) acts by repressing or activating genes coding for different myosin heavy chain (MHC) isoforms via T(3) receptors (TRs). The diverse function of T(3) is presumed to be mediated by TR-alpha(1) and TR-beta, but the function of specific TRs in regulating MHC isoform expression has remained undefined. In this study, TR-deficient mice were used to expand our knowledge of the mechanisms by which T(3) regulates the expression of specific MHC isoforms via distinct TRs. In fast-twitch extensor digitorum longus (EDL) muscle, TR-alpha(1)-, TR-beta-, or TR-alpha(1)beta-deficient mice showed a small but statistically significant decrease (P < 0.05) of type IIB MHC content and an increased number of type I fibers. In the slow-twitch soleus, the beta/slow MHC (type I) isoform was significantly (P < 0. 001) upregulated in the TR-deficient mice, but this effect was highly dependent on the type of receptor deleted. The lack of TR-beta had no significant effect on the expression of MHC isoforms. An increase (P < 0.05) of type I MHC was observed in the TR-alpha(1)-deficient muscle. A dramatic overexpression (P < 0.001) of the slow type I MHC and a corresponding downregulation of the fast type IIA MHC (P < 0.001) was observed in TR-alpha(1)beta-deficient mice. The muscle- and fiber-specific differences in MHC isoform expression in the TR-alpha(1)beta-deficient mice resembled the MHC isoform transitions reported in hypothyroid animals, i.e., a mild MHC transition in the EDL, a dramatic but not complete upregulation of the beta/slow MHC isoform in the soleus, and a variable response to TR deficiency in different soleus muscle fibers. Thus the consequences on muscle are similar in the absence of thyroid hormone or absence of thyroid hormone receptors, indicating that TR-alpha(1) and TR-beta together mediate the known actions of T(3). However, it remains unknown how thyroid hormone exerts muscle- and muscle fiber-specific effects in its action. Finally, although developmental MHC transitions were not studied specifically in this study, the absence of embryonic and fetal MHC isoforms in the TR-deficient mice indicates that ultimately the transition to the adult MHC isoforms is not solely mediated by TRs.

Adenosine Triphosphatases↗

PubMed2000

Placebo-controlled study of inhaled budesonide on indices of airway inflammation in bronchoalveolar lavage fluid and bronchial biopsies in cross-country skiers.

BACKGROUND: Asthma-like symptoms, methacholine hyperresponsiveness, use of inhaled steroids, airway inflammation, and increased tenascin expression in the reticular basement membrane have been reported in competitive cross-country skiers. OBJECTIVE: To investigate the effect of inhaled budesonide, 400 mug twice daily, on indices of airway inflammation in 'ski asthma', defined as asthma-like symptoms within the previous year and bronchial hyperresponsiveness to methacholine. METHODS: A randomised double-blind placebo-controlled parallel-group bronchial biopsy and bronchoalveolar lavage (BAL) study of 25 (19 male) competitive cross-country skiers (mean age 18 (16-20) years for a mean (range) treatment period of 22 (10-32) weeks over the competitive season. RESULTS: No changes were seen regarding cellular inflammation in the bronchial mucosa or tenascin expression. In the BAL fluid, both groups had a significant decrease in activated T-suppressor (CD8) lymphocytes and an increase in macrophages, with no differences across the groups. Within the budesonide group, there was a decrease in IL2 receptor-activated T-helper lymphocytes and an improvement in FEV(1). Asthma-like symptoms were unchanged in 17 (68%) skiers. Methacholine provocation test was negative in 15 subjects, and remained positive in 5 subjects in each group. The improvement in bronchial responsiveness occurred in both groups and was not accompanied by a decrease in cellular inflammation. CONCLUSIONS: We were unable to show any clear beneficial effect of budesonide in 'ski asthma'. As changes in training intensity probably accounted for the spontaneous improvement in bronchial responsiveness, more attention should be directed at reducing environmental stress to the airways than at attempting pharmacological modulation of induced inflammatory changes.

Administration, Inhalation↗

PubMed2000

Increased cell death and delayed development in the cerebellum of mice lacking the rev-erbA(alpha) orphan receptor.

The rev-erbA(alpha) gene, belonging to the steroid receptor superfamily of transcription factors, is highly conserved during evolution but little is known so far about its functions in development or in adult physiology. Here, we describe genetically altered mice lacking the rev-erbA(alpha) gene. These animals do not show any obvious phenotype in either fat tissue or skeletal muscle, despite the known regulation of rev-erbA(alpha) expression during adipocyte and myotube differentiation in vitro. However, during the second week of life, the cerebellum of rev-erbA(alpha) mutants presents several unexpected abnormalities, such as alterations in the development of Purkinje cells, delay in the proliferation and migration of granule cells from the external granule cell layer and increased apoptosis of neurons in the internal granule cell layer. Interestingly, the expression pattern of rev-erbA(alpha) suggests that the abnormalities observed in the external granule cell layer could be secondary to Purkinje cell alterations. Taken together, our data underline the importance of rev-erbA(alpha)expression for the appropriate balance of transcriptional activators and repressors during postnatal cerebellar development.

Animals↗

PubMed2000

Bone mineral density in diagnosis of osteoporosis: reference population, definition of peak bone mass, and measured site determine prevalence.

A population-based study was performed in order to compare different definitions of peak bone mass, and to apply the corresponding T-scores for different skeletal sites to a cohort of 70-yr-old women for studying the prevalence of osteoporosis. Bone mineral density (BMD) of the hip, lumbar spine, and forearm was measured by dual X-ray absorptiometry (Hologic 4500) in 296 women ages 16-31 yr and 210 women age 70 yr. Peak bone mass occurred in women in their early 20s at the proximal femur and at 28 and 31 yr at the spine and forearm, respectively. BMD cutoff levels were compared to machine-specific cutoff values for the different sites. When applied to our cohort of 70-yr-old women, the prevalence of osteoporosis at the total hip was 9-25%, depending on which peak bone mass the T-score of -2.5 was based. The prevalence in the spine was 28-33% and in the forearm 45-67%. Osteoporosis in at least one of the three measured sites was documented in 49-72% of the population sample. Our results show that the use of T-score to define osteoporosis results in a highly different prevalence rate in a given population depending on the reference population and the skeletal sites chosen for measurement.

Absorptiometry, Photon↗

PubMed2000

Aging-related changes in skeletal muscle. Mechanisms and interventions.

The aging-related motor handicap and the growing population of elderly citizens have enormous socioeconomic effects on the modern healthcare system. The mechanisms underlying impaired motor performance in old age are complex and involve the central and peripheral nervous systems and the muscle tissue itself. It is widely accepted that the aging-related loss of muscle mass, strength and quality has a significant detrimental impact on motor performance in old age and on the ability to recover from falls, resulting in an increased risk of fractures and dependency. Therefore, the prevention of falls and gait instability is a very important safety issue, and different intervention strategies have been used to improve motor performance among the aging population. There is general consensus that physical exercise is a powerful intervention to obtain long term benefits on muscle function, reduce the frequency of falls, and to maintain independence and a high quality of life in older persons. The results from studies using different types of hormone supplementation therapies have shown interesting and encouraging effects on skeletal muscle mass and function. However, the potential risks with both growth hormone and androgen treatment are not known and long term clinical trials are needed to address safety concerns and the effects on skeletal muscle. Recent advancements in cellular/molecular, physiological and molecular biological techniques will significantly facilitate our understanding of aging-related impairments of muscle function and contribute to the evaluation of different intervention strategies.

Actomyosin↗

PubMed1999

Rapid method for relative gene expression determination in human tissues using automated capillary gel electrophoresis and multicolor detection.

The aim of this study was to evaluate a direct and automated post-polymerase chain reaction (PCR) detection system to simultaneously determine the relative gene expression levels of nine cancer-related human genes. Total RNA was prepared from flash-frozen biopsies derived from human colorectal tumors or normal mucosa and reverse-transcribed to cDNA which was PCR-amplified using primer pairs corresponding to the studied genes. In each reaction, the forward primer was labeled with a fluorescent dye. The PCR products were pooled and an internal size standard with a uniquely colored fluorescent dye was added. The samples were then subjected to automated capillary gel electrophoresis. Fragment analysis software was used to calculate the relative gene expression using beta-actin as the reference gene. We found that automated capillary gel electrophoresis with multicolor detection is a rapid, accurate and highly reproducible method for separation and quantification of PCR-amplified cDNA.

Autoanalysis↗