Age-related changes in contractile properties and expression of myosin isoforms in single skeletal muscle cells.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
L Larsson
Publications and source records attributed to L Larsson.
Thyroid hormone effects on contractility and myosin composition of soleus muscle and single fibres from young and old rats.
1. Young (3-6 months) and old (20-24 months) male Wistar rat soleus muscles were examined for myosin isoform composition, fibre type, contractility and sarcoplasmic reticulum (SR) Ca2+ release properties either in control rats or in rats treated with thyroid hormone (3,5,3'-triiodothyronine, T3) for 4 weeks. 2. T3 treatment had a strong impact on myosin heavy chain (MyHC) and light chain (MyLC) isoform composition in both young and old rats. That is, all single fibres co-expressed type I and IIA (type I/IIA fibres) or type I, IIA and IIX MyHCs (type I/IIAX fibres) after treatment. Slow and fast MyLC isoforms, i.e. MyLC1s, MyLC1f, MyLC2s, MyLC2f and MyLC3, co-existed in each of the type I/IIA and I/IIAX fibres in variable proportions. 3. In old rats the maximum velocity of unloaded shortening (V0) was related to MyHC isoform composition: V0 for type I fibres was less than that for type I/IIA fibres which was less than that for type I/IIAX fibres. In young rats, on the other hand, V0 did not differ between pure type I fibres from controls and those co-expressing type I and type II MyHC isoforms from T3-treated rats. 4. Contraction and half-relaxation times of the isometric twitch were significantly longer in old than in young controls. This was paralleled by an age-related decrease in the caffeine threshold of the SR. Four weeks of T3 treatment eliminated the age-related differences in both speed of twitch contraction and caffeine thresholds. V0, on the other hand, was slower in old than in young animals, both control and T3-treated, when cells with a similar MyHC composition were compared. 5. In conclusion, thyroid hormone can substantially reverse at least some of the changes that occur in ageing muscle. Further, the age-related decline in V0 in soleus fibres from control and hyperthyroid rats suggests that: (1) the identification of beta/slow myosin isoforms is incomplete; or (2) the molecular characteristics of MyHC differ between young and old age; or (3) MyHC is not the only determinant of V0.
Aging↗
[Drug induced tetraparesis and loss of myosin. Mild types are probably overlooked].
Explore the source record for details and available documents.
Acute Disease↗
Fatigue of chronically overused motor units in prior polio patients.
This study was undertaken to investigate the mechanisms underlying fatigue of chronically overused motor units (MUs). The force of the tibialis anterior muscle (TA) and the firing properties of single MUs were studied during prolonged maximum voluntary effort in 10 prior polio patients selected such that daily living required all residual TA power. Almost all TA fibers were hypertrophic type I. Activities of intermyofibrillar succinate dehydrogenase (SDH) and calcium-stimulated myofibrillar adenosine triphosphatase (ATPase) were measured in single TA fibers from a representative patient. Neither insufficient motoneuron activation nor peripheral blocking of the electrical impulse played a major role in the loss of force during prolonged contraction or for slow recovery after contraction. The ratio of SDH to calcium-stimulated ATPase, representing the relation between energy resynthesis and energy utilization, was significantly (P < 0.001) lower in prior polio patients (0.230 +/- 0.096) compared to control (0.515 +/- 0.097) type I fibers.
Aged↗
Complement anaphylatoxin C3a and C5a formation in premature children with respiratory distress.
UNLABELLED: Premature children (n = 25) with respiratory distress (RD) were studied regarding complement activation and formation of the anaphylatoxins C3a and C5a. Blood samples were drawn on admission to the paediatric intensive care unit. In 18 of the patients RD was accompanied by other perinatal complications like pneumothorax or intracerebral haemorrhages. Seven of the premature children had RD without such complications. Preterm children with RD and with peri- and postnatal complications such as pneumothorax or intracerebral haemorrhage had increased concentrations in plasma of the anaphylatoxins C3a and C5a compared with preterm children with RD without these complications. There was a positive correlation between the plasma C3a and C5a concentrations in the preterm children. CONCLUSION: The present study indicates that isolated RD will appear without signs of complement activation and that complications like pneumothorax or intracerebral haemorrhages are associated with release of the anaphylatoxins C3a and C5a.
Analysis of Variance↗
Effects of removal of weight-bearing function on contractility and myosin isoform composition in single human skeletal muscle cells.
The purpose of this study was to investigate the effects of a 6-week period without weight bearing, achieved by bed rest, on the contractile behaviour, myosin isoform expression and myofibrillar protein content of single human muscle fibres. Percutaneous biopsied specimens of the quadriceps muscle were taken from three healthy male volunteers before and at the end of the experimental period. Maximum force normalised to cross-sectional area (specific tension), maximum velocity of unloaded shortening (V0), and myosin heavy chain (MyHC) and light chain (MyLC) isoform composition were measured in single membrane-permeabilised muscle cells obtained from these specimens. At the end of the experimental period, specific tension was reduced (P < 0.001) by 40% and there was a parallel decline in myofibrillar protein content per muscle cell volume. V0 did not change significantly in response to bed rest when data from all muscle cells were pooled. In two of the subjects, however, V0 decreased (P < 0.01-0.001) in muscle cells expressing the beta/slow (type I) MyHC isoform, but there was no change in fibres expressing type IIA or a combination of type IIA and IIB MyHCs. The slowing in type I MyHC fibres was associated with a change in the isoform composition of the regulatory MyLC.
Adult↗
Survey of consumption fish from Swedish waters for chlorinated pesticides and polychlorinated biphenyls.
In this survey eighty-seven samples of consumption fish comprising mainly of salmon, pike, eel, herring, whitefish, sea-trout, perch, pike-perch, mackerel, cod, flounder, plaice and sole collected between 1992-1993 have been analysed for the levels of chlorinated pesticides and polychlorinated biphenyls (PCBs). Considering the diversity in the sizes and assortment, locations, and time of catch, the samples are deemed to represent the normal fish variety available to the local people at various seasons of the year. Virtually all the samples contained CB-153 levels below the new established maximum limit of 0.1 mg/kg fresh weight. Results are compared with those obtained between 1985 and 1993. Neither the total PCB (on fat weight basis) nor CB 153 as a marker showed any clear trend for most of the fish species analysed, particularly for the short period 1991-1993. The pesticides, on the other hand, showed a rather good downward trend up till 1991; some of them seem to have virtually attained a steady state after 1991.
Animals↗
Age-related abnormalities in regulation of the ryanodine receptor in rat fast-twitch muscle.
The tibialis anterior (TA) muscles of 6-month-old and 24-month-old male Wistar rats, after being characterized, at the fast motor unit level, for twitch properties, were dissected and processed by a procedure [Margreth A., Damiani E., Tobaldin G. Biochem Biophys Res Commun 1993; 197: 1303-1311] aimed at obtaining a representative total membrane fraction comprising 70-80% of the total muscle content of sarcoplasmic reticulum (SR) and transverse tubule (TT) membranes (about 20 mg protein/g). Skeletal muscle membranes were analyzed for protein composition, and the content and functional properties of specific components of the free and junctional subcompartments of the SR and of junctional TT. Our results, while confirming a twitch prolongation in TA of old rats, do not demonstrate any associated age-related change concerning: (a) the overall number and functional properties of Ca2+ pumps, as characterized by kinetic parameters, Ca(2+)-dependency, and the protein isoform specificity of SR Ca(2+)-ATPase; (b) the number of functional junctional SR Ca(2+)-release channels, on the basis of Bmax values for high-affinity binding of [3H]-ryanodine to skeletal muscle membranes at optimal Ca2+; (c) the overall muscle dihydropyridine receptor/ryanodine receptor (RyR) ratio. We conclude from these findings, and the additional negative evidence for changes in membrane density of specific components of junctional SR, including 60 kDa Ca(2+)-calmodulin protein kinase, that this membrane domain, like the Ca(2+)-pump domain of the SR, are in no way basically altered at early stages of the aging process, as investigated here. Because of that, we allege particular significance to the occurrence of age-related, specific abnormalities in regulation of RyR in rat TA. The main supportive evidence is as follows: (a) an increased sensitivity to Ca2+ of the RyR of old muscle, and, more importantly; (b) an increased sensitivity to caffeine of [3H]ryanodine binding to the RyR at optimal Ca2+ and also optimal for the activity of the Ca(2+)-release channel. The results reported here also demonstrate that there are two classes of caffeine sites in rat TA muscle, as defined by differences in EC50 values at resting (pCa 7) and at high Ca2+ (pCa 4-5), that sites involved in stimulation of [3H]-ryanodine binding to the RyR are distinguished by a higher affinity (caffeine below mM), and that only these sites undergo age-related changes. Thus, although the underlying age-related abnormality of the RyR remains to be elucidated, it appears to satisfy the requirement for being regarded as a specific change, which in itself might argue for its being fundamentally related to the twitch prolongation of the muscle.
Aging↗
Prevalence of asthma in young cross-country skiers in central Scandinavia: differences between Norway and Sweden.
An increased prevalence of asthma in cross-country skiers has been reported previously. This study was conducted in order to evaluate the prevalence of asthma among young, elite cross-country skiers in Trøndelag, Norway and Jämtland, Sweden. These two regions in central Scandinavia have different climates during the winter season, with a coastal type in Trøndelag while Jämtland is characterized by a colder, drier, inland type of climate. The study population consisted of 171 skiers (118 from Norway, 53 from Sweden). The investigation included an asthma questionnaire, spirometry and methacholine provocation testing. The prevalence of self-reported asthma-related symptoms was 46% in Norway and 51% in Sweden. The prevalence of bronchial hyper-responsiveness (BHR) was significantly different between the two regions. In Norway, 14% of the skiers were hyper-responsive to methacholine compared to 43% in Sweden (P < 0.001). Moreover, the estimated prevalence of clinically diagnosed asthma was 12% in Norway and 42% in Sweden (P < 0.001). The self-reported frequency of respiratory allergy was higher in Sweden (32%) than in Norway (11%). However, on an individual basis, self-reported allergy did not predict occurrence of asthma or BHR. In conclusion, there is a high prevalence of BHR and asthma among young, elite cross-country skiers in central Scandinavia, especially in Sweden. Cross-country skiing may be a risk factor for the development of asthma. Longitudinal studies of cross-country skiers, and studies to acquire further knowledge of the mechanisms involved in the development of asthma are indicated.
Adolescent↗
Obstructive symptoms in athletes: is it asthma and what to do about it?
Explore the source record for details and available documents.
Anti-Inflammatory Agents↗
Local anaesthesia and propofol-fentanyl sedation for carotid artery surgery.
BACKGROUND: In patients undergoing carotid artery surgery with local anaesthesia (LA), a sedative/analgesic pharmacological supplement is appropriate in most cases in order to provide comfort. This adjunct should not preclude continuous clinical neurological monitoring. The aim was to investigate if a combination of fentanyl and propofol to supplement LA would provide comfort for the patient, allow continuous clinical neurological monitoring and absence of difficulties for the anaesthetist, and good conditions for surgery, including insertion of a shunt if this should become necessary. METHODS: During a 1-year period low doses of propofol and fentanyl were used to supplement LA in 36 cases of carotid artery surgery in 34 consecutive patients. A shunt was only used if neurological dysfunction occurred. Data on haemodynamics, pulmonary gas exchange, clinical neurological monitoring, and subjective opinions from patients, surgeons and anaesthetists were obtained. Morbidity within 30 days was documented. RESULTS: Conversion to general anaesthesia was undertaken in one patient, previously operated on the same artery, who became unconscious due to a stroke during manipulation of the artery before arteriotomy. No other adverse outcome was found within 30 days. In the remaining 35 cases the procedures were carried out under LA. Stump pressures below 50 mmHg were found in 17/35 cases. Intraoperative neurological dysfunction was detected in 10/35 cases (stump pressures between 23 and 60 mmHg). Shunting was easily performed, and rapidly relieved the neurologic symptoms in all these patients. Intraoperative respiratory and haemodynamic control was satisfactory. Ease of performance, including clinical neurological monitoring, was acknowledged by both anaesthetists and surgeons, and all 33 patients (35 operations) who were accessible for a postoperative interview stated that they would prefer the same regimen in the case of further surgery. CONCLUSION: The number of cases in this open, uncontrolled study does not permit an evaluation of this anaesthetic and sedative technique in terms of neurological and cardiac outcome. Thus, we simply want to inform about our positive experiences regarding patient acceptance and ease of performance in all relevant respects when fentanyl and propofol are used to supplement LA for carotid artery surgery.
Aged↗
Maximum shortening velocity and myosin isoforms in single muscle fibers from young and old rats.
Maximum velocity of unloaded shortening (Vo) and myosin heavy (MHC) and light chain (MLC) isoform compositions were determined in 185 single fibers from the extensor digitorum longus (EDL) and soleus muscles in 3- to 6- and 20- to 24-mo-old rats. In the soleus, fibers expressing the type I MHC isoform dominated in young and old animals. In the EDL, most fibers in the young animals expressed type IIb MHC or a combination of types IIx and IIb (type IIxb), whereas in the old animals type IIxb MHC fibers predominated. Vo was significantly (P < 0.01) lower (0.59 +/- 0.28 ml/s, n = 55) in soleus fibers from old than from young animals (1.12 +/- 0.46 ml/s, n = 48), despite the fact that all fibers expressed the type I MHC and slow MLC isoforms. In the EDL, Vo values in single fibers did not differ between young (2.18 +/- 0.58 ml/s, n = 43) and old animals (2.10 +/- 0.53 ml/s, n = 39). The mechanism underlying age-related slowing in soleus fibers is not known, but it has been suggested that there could be more than one beta/slow MHC isoform and that there is an age-related transition within these isoforms.
Aging↗
Rapid detection of thymidylate synthase gene expression levels by semi-quantitative competitive reverse transcriptase polymerase chain reaction followed by quantitative digital image analysis.
We describe a simplified and reliable polymerase chain reaction (PCR) method to quantify thymidylate synthase (TS) gene expression levels from clinical human tumor biopsy samples as small as 100 mg using the beta-actin housekeeping gene as a reference standard. The semiquantitative RT-PCR is carried out by the coamplification of the target template and an external competitor using primer pairs common to both templates in the same reaction vessel. Quantitative digital image analysis is performed directly after electrophoresis, thus mRNA quantification is done quickly and without the use of radioactive substances. The observed relative TS gene expression levels varied between 3- and 40-fold, but most of the values were grouped within a 10-fold range. There is an observed 89% correlation between TS mRNA expression and protein levels. These findings suggest that preliminary experiments used to determine the linear range of RT-PCR amplification in non-competitive semiquantitative PCR experiments, and the use of radioactive substances to quantify PCR products may be unnecessary.
Base Sequence↗
Exposure to bacteria in swine-house dust and acute inflammatory reactions in humans.
Inhalation of swine-house dust may cause an acute airway inflammatory condition (organic dust toxic syndrome). Thirty-eight healthy subjects were exposed to swine dust while weighing swine for 3 h. We studied the correlation between acute health effects and the inhaled bacterial exposure markers peptidoglycan (the main constituent of the cell walls of gram-positive bacteria, but also present in lesser amounts in gram-negative bacteria) and lipopolysaccharides (LPS; present only in gram-negative bacteria). LPS activity in airborne dust was measured with the Limulus amebocyte lysate assay (LPS(LAL)), and the total LPS was estimated from 3-hydroxy fatty acids, which were measured with gas chromatography-mass spectrometry (GC-MS) (LPS(GC-MS)). Peptidoglycan was estimated from muramic acid measured with GC-MS. The median (25th to 75th percentile) concentration of inhalable dust was 21 (16 to 25) mg/m3. LPS(LAL) was 1.2 (0.9 to 1.4) microg/m3; LPS(GC-MS) was 3.9 (2.5 to 4.9) microg/m3; and the peptidoglycan concentration in airborne dust was 6.5 (2.7 to 13) microg/m3. All exposure markers correlated significantly with an increase in serum interleukin-6. LPS(LAL) showed the highest correlation (r2 = 0.29) and total inhaled dust the lowest (r2 = 0.09). LPS(LAL) also correlated with symptoms and with an increase in bronchial responsiveness and decrease in vital capacity (VC). Peptidoglycan, but not LPS(LAL), correlated with an increase in the blood granulocyte concentration and in body temperature. The results suggest that several microbial agents in inhaled swine-house dust may contribute to acute systemic health effects.
Administration, Inhalation↗
Suicidal feelings in a population sample of nondemented 85-year-olds.
OBJECTIVE: The authors studied the 1-month frequency of suicidal feelings among very old people. METHOD: A population sample (N = 345) of nondemented 85-year-olds in Gothenburg, Sweden, were examined by a psychiatrist. Suicidal feelings were rated by the system of Paykel et al. Mental disorders were diagnosed according to DSM-III-R. RESULTS: Of the mentally healthy subjects (N = 225), 4.0% had thought during the last month that life was not worth living, 4.0% had had death wishes, and 0.9% had thought of taking their own lives. None had seriously considered suicide. The figures were higher among subjects with mental disorders (N = 120); 29.2% had thought that life was not worth living, 27.5% had had death wishes, 9.2% had thought about taking their lives, and 1.7% had seriously considered suicide. Among the subjects with mental disorders, including depression, suicidal feelings were associated with greater use of anxiolytics but not of antidepressants. Women who felt that life was not worth living had a higher 3-year mortality rate than did women without these feelings (43.2% versus 14.2%). This finding was independent of concomitant physical and mental disorders. CONCLUSIONS: Mild suicidal feelings are common in elderly subjects with metal disorders but infrequent in the mentally healthy. The substantially higher mortality rate in women who felt that life was not worth living, compared to women who did not, suggests these feelings must be taken seriously. Because of the high suicide rate in the elderly, there is a need for better diagnosis and treatment of mental disorders in this age group.
Aged↗
Comparisons of studies on diabetic complications hampered by differences in GHb measurements.
OBJECTIVE: To compare glycated hemoglobin (GHb) values of the relationship between glycemic control and complications of diabetes from laboratories involved in long-term studies (Steno, Oslo, Stockholm, Diabetes Control and Complications Trial, and Linköping.) RESEARCH DESIGN AND METHODS: Blood samples were collected from 25 subjects selected to represent the clinically relevant measurement range. Fresh whole-blood samples were distributed and analyzed within 4 days of sample collection. Pretreatment of samples and analyses of GHb were performed according to the routine method of each study's central or reference laboratory. Results from each laboratory were compared with the group mean, i.e., the mean of all results for each sample. RESULTS: Regression analyses with the group mean values as independent variables and results from each laboratory as dependent variables showed that Oslo's result had a slope significantly different from the group mean. Laboratories used by the DCCT, Oslo, and Steno studies gave, on average, 0.4, 0.4, and 0.7% higher HbA1c readings than the group mean, respectively, while HbA1c results from Linköping and Stockholm were, on average, 0.6 and 1.0% lower, respectively. CONCLUSIONS: There were large differences in GHb values among laboratories participating in studies of diabetic complications. The present data offer a guide to the comparison of results from the studies and underscores the need for standardization of GHb measurements.
Diabetes Complications↗
Lithofibrin. A new remarkably stable substance found in renal stones.
Besides inorganic constituents, renal stones contain organic matter known as stone matrix. We have examined such matrix obtained from stones that had been crushed by extracorporeal shock-wave lithotripsy, in order to determine its chemical properties. Morphologically, the matrix was composed of fibers of different colors, most of them exhibiting autofluorescence. Proteins or any other well-known biochemical material were not present. It was remarkably stable against chemical degradation, and could not be dissolved in hot concentrated acids or bases or any common organic solvent. Elementary analysis revealed carbon (60.8%), oxygen (26.9%), nitrogen (7.6%), hydrogen (5.3%) and sulfur (0.77%) to be present. Furthermore, X-ray emission spectroscopy revealed the presence of titanium and chromium. Solid-phase 13C NMR spectroscopy revealed the presence of aromatic and aliphatic carbon as well as carbon bound to O and/or N. The material was paramagnetic. All findings indicated the matrix to be composed of a new class of organic compound, probably a polyaromatic heterocyclic organic material. We welcome suggestions on further methods that can ultimately elucidate the nature of lithofibrins.
Humans↗
Human-microcomputer relations in an integrated laboratory service: the users' perspective.
The Motala Clinical Chemical Laboratory includes both central (hospital) and peripheral primary health care units. A laboratory computer system has been developed that is shared by all units. In order to illuminate the crucial human-computer interaction, the authors did a questionnaire study of the attitudes and experiences of the whole laboratory staff. The null hypothesis of the study-that computerizing is a threat to the users-was rejected. The quality of the laboratory work and reports was also felt to be improved.
Adult↗