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Biomedical subjects

M Vornanen

Publications and source records attributed to M Vornanen.

At least 37 records · Page 2Linked to original sources
PubMed1999

Na+/Ca2+ exchange current in ventricular myocytes of fish heart: contribution to sarcolemmal Ca2+ influx

Influx of extracellular Ca2+ plays a major role in the activation of contraction in fish cardiac cells. The relative contributions of Na+/Ca2+ exchange and L-type Ca2+ channels to Ca2+ influx are, however, unknown. Using a physiological action potential as the command pulse in voltage-clamped heart cells, we examined sarcolemmal Ca2+ influx through Na+/Ca2+ exchange and L-type Ca2+ channels in crucian carp (Carassius carassius L.) ventricular myocytes. When other cation conductances were blocked, a Ni2+-sensitive current with the characteristic voltage- and time-dependent properties of the Na+/Ca2+ exchange current could be distinguished. At the maximum overshoot voltage of the ventricular action potential (+40 mV; [Na+]i=10 mmol l-1), the density of the Na+/Ca2+ exchange current was 2.99+/-0.27 pA pF-1 for warm-acclimated fish (23 degrees C) and 2.38+/-0.42 pA pF-1 for cold-acclimated fish (4 degrees C) (means +/- s.e.m., N=5-6; not significantly different, P=0.26). The relative contributions of the Na+/Ca2+ exchanger and L-type Ca2+ channels to Ca2+ influx were estimated using two partly different methods. Integration of the Ni2+-sensitive Na+/Ca2+ exchange current and the verapamil- and Cd2+-sensitive L-type Ca2+ current suggests that, during the action potential, approximately one-third of the activating Ca2+ comes through Na+/Ca2+ exchange and approximately two-thirds through L-type Ca2+ channels. An alternative method of analysis, using the inward tail current as a measure of the total sarcolemmal Ca2+ flux from which the Ni2+-sensitive Na+/Ca2+ exchange current was subtracted to obtain the Ca2+ influx through the channels, suggests that L-type Ca2+ channels and Na+/Ca2+ exchange are almost equally important in the activation of contraction. Furthermore, the time course of cell shortening is not adequately explained by sarcolemmal Ca2+ influx through the channels alone, but is well approximated by the sum of Ca2+ influx through the channels and the exchanger. The present results indicate that reverse Na+/Ca2+ exchange in crucian carp ventricular myocytes has sufficient capacity to trigger contraction and suggest that the exchange current makes a significant contribution to contractile Ca2+ during the physiological action potential. The relative significance of channels and exchanger molecules in sarcolemmal Ca2+ entry into crucian carp ventricular myocytes was unaffected by thermal acclimation when determined at 22 degrees C.

Journal Article↗
PubMed1999

Contractile properties of atrial and ventricular myocardium of the heart of rainbow trout oncorhynchus mykiss: effects of thermal acclimation

Atrial and ventricular myocardium perform different tasks in the pumping work of the vertebrate heart, which are reflected in their contractile properties. Although atrial contraction is assumed to have an important role in the function of fish heart, the contractile properties of atrial and ventricular myocardium have not been directly compared in any fish species. The objective of this study was to clarify any contractile differences in the heart of teleost fish and, in particular, to elucidate the contribution of myofibrillar ATPase and intracellular Ca(2+) stores to the characteristics of atrial and ventricular contraction. Experiments were conducted on thermally acclimated rainbow trout Oncorhynchus mykiss to determine whether the effects of temperature adaptation are the same in atrial and ventricular tissue. It was shown that the rate of isometric contraction is much faster in atrial than in ventricular tissue of the fish heart and that acclimation to cold increases the rate of contraction in both cardiac compartments. The rapid contraction kinetics of the atrial tissue were associated with higher myofibrillar ATPase activity and faster Ca(2+) uptake rate of the sarcoplasmic reticulum (SR) compared with ventricular tissue. Similarly, the faster kinetics of contraction following cold acclimation could be attributed to enhancement of the myofibrillar and/or SR function. The atrio-ventricular and temperature-induced differences were also expressed in the recovery of force from inactivation, i.e. in the mechanical restitution. The refractory period and the rate constant of force restitution were shorter in atrial than in ventricular muscle tissue. Similar differences also existed between the tissues of cold-acclimated (CA, 4 degrees C) and warm-acclimated (WA, 17 degrees C) fish. The fast recovery of force from inactivation in the heart of the CA trout was, at least in part, due to more active SR. Furthermore, it was shown that the force of atrial contraction in the CA trout is sensitive to ryanodine (10 (&mgr;)mol l(-)(1)), a Ca(2+)-release channel blocker of SR, at physiological body temperature (4 degrees C) and at a physiological pacing rate (0.6 Hz). This finding indicates that the Ca(2+) stores of SR contribute to activation of cardiac contraction in the fish heart, and that the SR of fish heart is able to retain its Ca(2+) load at low body temperatures, i.e. the Ca(2+ )release channels of SR are not leaky in the cold. The present data show that in the atrial tissue of CA trout, the SR directly contributes to the cytosolic Ca(2+) and that in the atrium and ventricle of CA trout, the SR significantly accelerates the recovery of contractility from inactivation. The fast recovery from inactivation allows relatively high heart rates and therefore adequate cardiac outputs at low environmental temperatures for the cold-active rainbow trout.

Journal Article↗
PubMed1998

Muscle capillary supply in hind limb and diaphragm of the common shrew (Sorex araneus).

Shrew species of the subfamily Soricinae have unusually high metabolic rates when compared to Crocidurinae shrews and other similar-sized mammals. The aim of this study was to clarify whether the high basal metabolic rate of Soricinae shrews is reflected in a high capillary density in their muscles. To this end, the capillary supply of four limb muscles and diaphragm of the common shrew (Sorex araneus) was quantified from cross-sectioned muscles. The capillary densities of the limb muscles were 2575 +/- 329, 3111 +/- 299, 2812 +/- 197 and 2752 +/- 173 capillaries mm-2 fibre area in gastrocnemius lateralis, g. medialis, plantaris and soleus, respectively. Capillary density of the shrew diaphragm (6691 +/- 1057) was double that of the limb muscles. This value is among the highest ever measured in mammals. In general, the capillary supply in the hind limb of the common shrew is about 3-4 times higher than commonly found in the leg muscles of the laboratory rat or other bigger mammals, but similar to those in Crocidurinae shrews and some small rodents. Thus the high resting metabolism of the common shrew is not associated with an extraordinarily high capillary density. The apparent disparity between basal metabolic rate and muscle capillary supply in S. araneus is probably due to the small aerobic scope of shrews in the subfamily Soricinae.

Analysis of Variance↗
PubMed1998

Association of CagA-positive and CagA-negative Helicobacter pylori strains with patients' symptoms and gastritis in primary care patients with functional upper abdominal complaints.

BACKGROUND: CagA-positive Helicobacter pylori strains have been reported to be associated with peptic ulcer or malignancy more often than cagA-negative strains. Less is known about the relation of H. pylori serology (CagA-negative or CagA-positive) to histologic changes in the stomach of patients with functional upper abdominal complaints. The association of H. pylori status with patient symptoms or with different subgroups of non-organic dyspepsia is also obscure. In the present study patients' symptoms and their relation to H. pylori serology (H. pylori-negative, H. pylori-positive but CagA-negative, and H. pylori-positive and CagA-positive) were evaluated in general practice patients who had functional upper abdominal complaints. The association of H. pylori serology with different symptom-based subgroups of functional upper abdominal complaints was also assessed. The severity and activity of inflammation and the presence of atrophy and intestinal metaplasia in the antrum and body were evaluated and compared with H. pylori status. METHODS: Four hundred consecutive unselected dyspeptic patients in primary care were investigated by means of gastroscopy, upper abdominal ultrasound, laboratory screening including H. pylori and CagA serology, and other examinations if needed. Of these patients 193 with functional upper abdominal complaints were enrolled in this study. RESULTS: Of the study patients 87 (45%) were H. pylori-negative, 70 (36%) were H. pylori- and CagA-positive, and 36 (19%) were H. pylori-positive but CagA-negative. There were no differences in the occurrence of any dyspeptic symptoms between H. pylori-related subgroups. Nor was there an association between H. pylori status and symptom-based subgroups in our study patients. Inflammation of the stomach was related to H. pylori infection, but CagA-seropositive patients did not have moderate or severe inflammation more often than CagA-seronegative ones. CagA-seropositive patients with functional upper abdominal complaints did not have atrophic changes or intestinal metaplasia in the stomach more often than those who were CagA-negative. CONCLUSIONS: H. pylori or more specific CagA serology is not associated with any specific symptom profile of dyspepsia or with any symptom-based subgroups in patients with functional upper abdominal complaints in primary care. The study patients with CagA seropositivity did not have more severe histologic changes in the stomach than the patients who were H. pylori-seropositive but CagA-seronegative.

Abdominal Pain↗
PubMed1998

Ca2+-ATPase activity and Ca2+ uptake by sarcoplasmic reticulum in fish heart: effects of thermal acclimation.

This study was designed to compare the activities of sarcoplasmic (SR) Ca2+-ATPase and Ca2+ uptake in fish and mammalian hearts and to determine whether thermal acclimation has any effect on the function of the cardiac SR in fish. To this end, we measured thapsigargin-sensitive Ca2+-ATPase activity and thapsigargin-inhibitable Ca2+ uptake velocity in crude cardiac homogenates of newborn and adult rats and of two teleost fish (crucian carp and rainbow trout) acclimated to low (4 degrees C) and high (17 degrees C and 24 degrees C for trout and carp, respectively) ambient temperatures. The TG-sensitive Ca2+-ATPase activity was highest in adult rat, and the corresponding activities of cold-acclimated trout, warm-acclimated trout, warm-acclimated carp, cold-acclimated carp and newborn rat were 76, 58, 43, 28 and 23 %, respectively, of that of the adult rat at 25 degrees C. SR Ca2+ uptake velocity, measured using Fura-2 at room temperature (approximately 22 degrees C), was highest in cold-acclimated trout, and the values for adult rat, warm-acclimated trout, newborn rat, warm-acclimated carp and cold-acclimated carp were 93, 56, 24, 21 and 14 % of the uptake velocity of cold-acclimated trout, respectively. When corrected to the body temperature of the animal, the relative rates of SR Ca2+ uptake were 100, 26, 19, 18, 11 and 2 % for adult rat, newborn rat, cold-acclimated trout, warm-acclimated trout, warm-acclimated carp and cold-acclimated carp, respectively. These findings show that SR Ca2+ uptake is slower in fish than in mammalian hearts and that marked species-specific differences exist among teleost fish in this respect. Furthermore, acclimation to cold increases the Ca2+ uptake rate of trout cardiac SR (complete thermal compensation) but decreases the SR Ca2+ uptake rate of crucian carp heart. This difference in acclimation response probably reflects the different activity patterns of the two species in their natural habitat during the cold season.

Adaptation, Physiological↗
PubMed1998

L-type Ca2+ current in fish cardiac myocytes: effects of thermal acclimation and beta-adrenergic stimulation.

A patch-clamp analysis of L-type Ca2+ current in ventricular myocytes of cold- and warm-acclimated rainbow trout (Oncorhynchus mykiss) and crucian carp (Carassius carassius) hearts was performed. Trout were acclimated at 4 and 17 degrees C and carp at 4 and 24 degrees C for a minimum of 4 weeks. Ventricular myocytes were isolated by enzymatic dissociation using collagenase and trypsin. Marked species-specific differences were noted in Ca2+ current density and its ss-adrenergic regulation. The density of basal Ca2+ current in crucian carp (6.9-7.4 pA pF-1) was almost double that of trout (4.2-4.5 pA pF-1) ventricular myocytes. Maximal beta-adrenergic stimulation increased Ca2+ current by approximately 2.3-fold in trout but by only 1.4-fold in crucian carp, so that Ca2+ current densities in the presence of 10 micromol l-1 isoprenaline were almost equal in trout (8.6-10.5 pA pF-1) and carp (9.6-10.4 pA pF-1) cardiac cells. Direct activation of adenylate cyclase by forskolin (10 micromol l-1) was also associated with similar interspecies differences in the stimulation of Ca2+ current. Thermal acclimation did not change either the density or the kinetics of L-type Ca2+ current in crucian carp ventricular myocytes. In trout cardiac cells, thermal acclimation had no effects on the density of Ca2+ current, but the rate of current inactivation was accelerated after acclimation to cold temperature. As a consequence of faster current decay, the contribution of sarcolemmal Ca2+ current to total cellular [Ca2+] was smaller in cold-acclimated than in warm-acclimated trout. The responses of Ca2+ current to maximal beta-adrenergic stimulation by isoprenaline or to direct activation of adenylate cyclase by forskolin were not changed by thermal acclimation in either species. It is concluded (1) that the density of sarcolemmal Ca2+ current is not increased after acclimation to cold, (2) that sarcolemmal Ca2+ influx through L-type Ca2+ channels can make a significant contribution to contractile [Ca2+] in both teleost species studied and (3) that ss-adrenergic stimulation of Ca2+ current is more important in modulating cardiac contractility in trout than in carp.

Acclimatization↗
PubMed1997

Restitution of contractility in single ventricular myocytes of guinea pig heart.

OBJECTIVE: Our aim was to assess the extent to which changes in intracellular Ca2+ stores contribute to mechanical restitution in heart muscle. METHODS: Single, isolated guinea pig ventricular cells were voltage clamped at -45 mV and stimulated continuously at 0.5 or 2 Hz with 200 ms depolarizing pulses (35 degrees C). The recoveries of the peak of contraction force (Fp) and the calcium current (ICa) between beats were measured in contractions interpolated at various intervals (td) after a conditioning twitch. Recovery of SR Ca2+ load was inferred from the peak magnitude (Cp) of similarly interpolated contractures, induced by rapid application of 5 mM caffeine. RESULTS: For a conditioning stimulus rate of 0.5 Hz, both Fp and ICa were very small for small td and recovered along similar time courses with a t1/2 of about 50 ms. Cp was maximal at as early a time after a previous contraction as could be measured, at which time Fp was 56% of maximal. Cp declined throughout the stimulus interval to about 50% of its maximal value. Similar results were obtained for a conditioning stimulus rate of 2 Hz, at which rate both Fp and Cp were increased by a factor of 2. CONCLUSIONS: The time course of mechanical restitution is coincident with the recovery of ICa from inactivation. Caffeine-releasable intracellular calcium stores are fully recovered soon after a contraction and well before mechanical restitution is complete.

Animals↗
PubMed1997

Kikuchi's disease: report of three cases and an overview.

We describe, to our knowledge, the first native Finnish patients with Kikuchi's histiocytic necrotizing lymphadenitis. The diagnosis was based in all cases on histopathological findings in open biopsy. The disease was first detected in Japan in 1972, but in Scandinavia, until this decade, there had been no cases reported. Our patients were young, otherwise healthy women who had cervical lymphadenopathy, fever, and fatigue as their main symptoms. In two of them, the disease was mild and subsided spontaneously within 2-6 months. One patient with more fulminant lymphadenopathy was treated with antimicrobial and antiinflammatory drugs. She became symptomless in 3 months. The cause of Kikuchi's disease is unknown. A viral or postviral hyperimmune reaction has been proposed as its etiology. Malignant lymphoma and systemic lupus erythematosus are differential diagnoses. Histopathological findings are pathognomonic and pathologists must be aware of its typical characteristics.

Adult↗
PubMed1997

Sarcolemmal Ca influx through L-type Ca channels in ventricular myocytes of a teleost fish.

The whole cell patch clamp method was used to measure Ca current through L-type Ca channels in enzymatically isolated ventricular myocytes of crucian carp (Carassius carassius L.) heart. Fish were acclimated to 22 degrees C for more than 4 wk, and properties of Ca current were measured at room temperature (21 +/- 1 degrees C). Depolarizing voltage steps from -50 mV evoked rapidly activating Ca currents, which exhibited a bell-shaped voltage dependence with peak amplitude at 0 mV. The currents were suppressed by nifedipine (5 microM), verapamil (2.5 microM), and Cd2+ (175 microM). The current amplitude was increased by 67.5 +/- 17.2% (n = 5) in the presence of 1 microM isoproterenol. Steady-state inactivation and activation curves showed half-maximal inactivation at -31.3 +/- 0.95 mV, with a slope factor of 5.88 +/- 0.51, and half-maximal activation at -10.6 +/- 1.65 mV, with a slope factor of 7.84 +/- 0.54 (n = 9). The overlap of inactivation and activation curves suggests the presence of a small window current, which is maximally 4% of the peak current at -27 mV. The density of L-type Ca current was 6.95 +/- 0.79 pA/pF at 0 mV (n = 35). A total increment in cellular Ca contributed by L-type Ca current during a 500-ms voltage clamp pulse was calculated from the integral of Ca current and cell volume. The charge transfer through L-type Ca current was 0.325 +/- 0.023 pC/pF, and the mean cell volume was 1,377 +/- 44 microns3. The increment in total cellular Ca by Ca influx through L-type Ca channels was calculated to be 39.3 +/- 2.8 microM. These findings imply that Ca influx through L-type Ca channels can contribute significantly to the activation of contraction in the ventricular myocytes of fish heart.

Animals↗
PubMed1997

Histopathological and bacteriological findings in prurigo nodularis.

Prurigo nodularis is a chronic disease with unknown aetiology. Biopsy specimens of 43 patients with prurigo nodularis were taken for histopathological and mycobacteriological analyses. By conventional histopathology, 25 (58%) samples, and by immunostaining for S100 protein, 31 (72%) samples had changes relevant to prurigo nodularis. Twelve (28%) of the samples were positive for acid fast bacilli in tissue staining by Ziehl-Neelsen technique, including 4 of the 6 samples also positive for mycobacteria in cultivation. The results verified the usefulness of S100 staining in detection of neural hyperplasia in dermal nerves, a feature regarded as diagnostic for prurigo nodularis. They also indicated that atypical mycobacteria may be a contributing factor in prurigo nodularis.

Adult↗
PubMed1997

Changing trends in the incidence of non-Hodgkin's lymphoma in Europe. Biomed Study Group.

Non-Hodgkin's lymphoma (NHL) is not a uniform disease entity, and in order to investigate the reported changes in incidence we have set up a study in seven population-based cancer registries in Europe. The study is designed to look at changes in the incidence of total NHL and disease subgroups using standard definitions and methodology. The registries are based in Leeds, Dijon, Kuopio, Odense, Florence, Eindhoven, and Ragussa. The classification system we have used is based on the REAL classification and has utility for epidemiological studies. We have used it to convert data sets which have utilized both local cases and the ICD-O classification. In order to improve data reproducibility, CLL/LL, myeloma/MGUS, lymphoblastic disease, and Hodgkin's disease have been excluded because of the difficulty in defining incident cases accurately. The preliminary results of this study show that there is still an upward trend in incidence rate and that in Yorkshire this is 3% per annum in total NHL. The subgroups which are increasing are extranodal and nodal peripheral T-cell lymphoma. Similar increases in incidence have been reported for the other registries. We conclude that there is a continued upward trend in incidence of NHL, the causes of which are uncertain.

Europe↗
PubMed1996

Contribution of sarcolemmal calcium current to total cellular calcium in postnatally developing rat heart.

OBJECTIVE: The aim was to determine the contribution of sarcolemmal Ca influx through L-type Ca current to total cellular Ca in newborn and postnatally developing rat heart. METHODS: Whole cell voltage clamp was used to study L-type Ca current in freshly isolated ventricular cells of 1, 6, 10, 15, 30-day-old and adult (120-150 days) rats. Amplitude, current density, inactivation rate and time integral of Ca current were determined at the experimental temperature of 36 degrees C. Width, length, surface area, volume and surface-to-volume ratio of the isolated cells were also determined. Using the time integral of Ca current and volume of the myocytes the increment in total cellular Ca was calculated for the six developmental stages. RESULTS: The amplitude of Ca current increased strongly during the postnatal maturation from 277 +/- 25 pA at day 1 to 1961 +/- 98 pA in the adult rat (P < 0.001). This increase was due to an almost proportional increase in cell size; accordingly the density of Ca current remained fairly constant, being 16.9 +/- 1.8, 17.0 +/- 1.8, 22.8 +/- 1.4, 21.2 +/- 1.5, 16.2 +/- 2.0 and 15.9 +/- 0.7 pA/pF for 1, 6, 10, 15, 30-day-old and adult rats, respectively. Charge transfer by Cd-sensitive Ca current during 200 ms voltage pulse from -45 mV to 0 mV increased from 7.18 +/- 1.00 pC at day one to 24.80 +/- 1.80 pC in the adult rat heart (P < 0.001). When normalized to the capacitive surface area of the myocytes the charge transfer by L-type Ca current was more than double in newborns (0.429 +/- 0.074 pC/pF) as compared to the adults (0.188 +/- 0.016 pC/pF) (P < 0.01). The difference is explained by slower inactivation rate of Ca current in newborn than adult rats. Time constant of the fast component was 5.92 +/- 0.62 ms and 4.5 +/- 0.4 ms (P < 0.05) for 1-day-old and adult rat, respectively. Time constant of the slow component decreased from 27.7 +/- 2.0 to 21.7 +/- 3.0, although the difference was not statistically significant (P = 0.26). The increment in total cellular Ca due to Ca influx through Ca channels was 54 +/- 9 mumol l-1 in 1-day-old rat and decreased steadily during postnatal maturation to 8 +/- 1 mumol l-1 in the adult rat (P < 0.001). The change is partly due to faster inactivation of Ca current in adults but mainly as a consequence of decreasing surface-to-volume ratio of growing myocytes. Sarcolemmal surface area increases almost 9 times from 1.001 x 10(3) microns2 at day 1 to 8.675 x 10(3) microns2 for the adult rat, whereas increase in cell volume is about 28-fold from 0.991 x 10(3) to 27.74 x 10(3) microns3: accordingly surface-to-volume ratio decreases from 1.05 +/- 0.02 at day 1 to 0.36 +/- 0.01 in the adult rat (P < 0.01). CONCLUSIONS: Contribution of sarcolemmal Ca influx through L-type Ca channels is over 6 times higher in newborn than mature rats. Therefore, the strong dependence of neonatal rat heart on extracellular Ca for contractile activation is, at least partially, explained by greater contribution of L-type Ca current to intracellular Ca.

Animals↗
PubMed1996

Computer analysis and plotting of physiologic signals in cardiac muscle research.

A program (Caphys) for IMB-compatible microcomputers is described which facilitates off-line analysis of muscle physiologic signals. Caphys was written as an analysis tool for data acquired through AxoTape program (Axon Instruments). Parameters for time course and amplitude of isometric contractions and intracellularly recorded action potentials are calculated by the program. The features of Caphys include low-pass filtering and derivation of the measured signals. The programs allows also screen display and printer output of the analyzed physiological tracings. Caphys is a suitable extension for the commercially available acquisition software, making the analysis and plotting of primary physiologic data faster and more efficient.

Animals↗
PubMed1996

Mycobacteria in prurigo nodularis: the cause or a consequence?

BACKGROUND: Prurigo nodularis (PN) is a chronic skin disorder; its cause remains unknown. OBJECTIVE: We evaluated mycobacteria as a possible cause of PN. METHODS: Forty-three patients with PN were examined. Skin biopsy specimens were obtained for microbiologic and histopathologic studies. The patients were tested for intracutaneous reactivity to 12 mycobacterial antigens with the Mantoux technique. RESULTS: Six specimens (14%) grew mycobacteria in culture: M. avium-intracellulare (3), M. malmoense (1), and Mycobacterium sp. (2). Histopathologically, 12 samples (28%) were positive for acid-fast bacilli, and granulomatous changes were present in one sample. Patients whose cultures were positive for mycobacteria had significantly larger skin reactions to mycobacterial antigens. Two patients underwent 2 years of antituberculous chemotherapy; one had an excellent response and the other a partial response. CONCLUSION: Detection of mycobacteria by culture or staining, combined with elevated skin reactivity to mycobacteria in a high proportion of patients with PN, suggests a mycobacterial cause.

Adult↗
PubMed1996

Slowly growing mycobacteria and chronic skin disorders.

We evaluated the role of mycobacteria in chronic skin manifestations. The etiologies of chronic skin disorders in 90 patients were analyzed by culture, histopathologic examination, and skin testing for mycobacteria. There were 20 clinical diagnoses; prurigo nodularis was the most common diagnosis (43 patients). Cultures were incubated at 32 degrees C and 36 degrees C for 6 months. Fourteen cultures (16%) yielded the following mycobacteria: Mycobacterium tuberculosis (5), Mycobacterium avium/Mycobacterium intracellulare complex (3), Mycobacterium malmoense (2), and other mycobacteria (4). Acid-fast bacilli were detected in 24 (28%) of the 86 histopathologic specimens examined, including nine of the 14 culture-positive specimens. Granulomatous infection was present in three specimens (3%); cultures of two of these specimens yielded M. tuberculosis, and culture of one was negative. Skin reactivity to 12 mycobacterial antigens was tested. The patients for whom staining and/or culture was positive for mycobacteria had significantly larger skin reactions to M. malmoense antigen (P < .001) than did the patients with bacteriologically negative skin disorders. There was no correlation between the species isolated and the skin reactivity to the species-specific antigen.

Adolescent↗
PubMed1995

Fiber types and myosin heavy chain composition in muscles of common shrew (Sorex araneus).

Red-toothed shrews of subfamily Soricinae are small mammals with very high mass-specific metabolic rate. Owing to their high aerobic power they are interesting objects for studies concerning the limits and constraints of skeletal muscle adaptation. In order to clarify the correlation between metabolic rate and muscle properties, we have analyzed fiber types, fiber size, and myosin heavy chain composition of the common shrew (Sorex araneus) and compared them to those of rat (Rattus norvegicus). Three distinct differences between shrew and rat muscles were noted. 1) The fibers of shrew muscles are exceptionally small in comparison to rat myofibers. 2) Electrophoretic and histochemical analysis showed that shrew muscles are composed of only fast fibers (fiber types IIB and IID), the slow type I fibers being totally absent. 3) The shrew muscles are much more homogenous than rat muscles in regard to myosin heavy chain and fiber type composition. The shrew diaphragm consists exclusively myosin heavy chain type IId (MHCIId), while masseter and soleus are composed 95% and 87% of MHCIId, respectively. Other four studied muscles contain MHCIIb and MHCIId approximately in equal proportions. The present findings show that shrew muscles are composed of small, highly aerobic, fast type II fibers, which may be sufficiently fatigue-resistant to function both as postural muscles and to power fast and high frequency movements of limbs and diaphragm.

Animals↗