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At least 577 records · Page 32Linked to original sources
PubMed2004

Short-time exposure to vinclozolin in utero induces testicular maldescent associated with a spinal nucleus alteration of the genitofemoral nerve in rats.

BACKGROUND/PURPOSE: Vinclozolin (V), a known antiandrogen, has been used widely to protect fruits, vegetables, and turf from fungus damage. The aim of this study was to clarify the effect of V on both the development of the spinal cord nucleus and testicular descent in rats. METHODS: Pregnant rats were administered 200 mg/kg/d of V from day 16 to 18 of gestation. At 5 days of age, the genitofemoral nerve (GFN) of male pups was identified on the psoas muscle, and diamidinophenyl indole was applied to the proximal cut end of the GFN. Forty-eight hours later, the T11 to L4 level of the spinal cord was removed, and 30-microm frozen serial sections were made. Next, the spinal nuclei labeled in a retrograde fashion by diamidinophenyl indole (DAPI) were examined with a fluorescence microscope. Additional male pups survived until 60 days of age to evaluate the position of the testes. RESULTS: The size of the DAPI-labeled spinal nuclei were smaller in the V-treated rats than in the control rats. The average number of the DAPI-labeled spinal nuclei decreased significantly more in the V-treated rats (176+/-33) than in the controls (247+/- 21; P <.05) during the newborn period. At 60 days of age, 15 of the 26 male rats showed either unilateral or bilateral undescended testes in the V-treated rats. The incidence of cryptorchidism was also significantly higher in the V-treated rats (57.7%) than in the controls (0%; P <.05). CONCLUSIONS: The antiandrogenic effect of the prenatal administration of V inhibited the development of the GFN nucleus in the spinal cord and induced testicular maldescent in rats. These results support the hypothesis that androgens regulate the descent of the testis through GFN development.

Androgen Antagonists↗
PubMed1993

The effect of lattice spacing change on cross-bridge kinetics in rabbit psoas fibers.

The effect of compression on the elementary steps of the cross-bridge cycle was investigated with the sinusoidal analysis technique and ATP hydrolysis rate measurement. The lattice spacing of rabbit psoas muscle fibers was osmotically compressed with a macromolecule, dextran T-500 (0-16%). The effects of MgATP, MgADP, Pi on exponential processes (B), (C), (D), and isometric tension were studied at different dextran concentrations. The experiments were performed at the saturating Ca concentration (pCa 4.5-4.8), 200 mM ionic strength, pH 7.0, and 20 degrees C. Our results show that the fiber width decreased linearly with an increase in the dextran concentration, and the width measurement was perfectly correlated with the lattice spacing measurement using equatorial x-ray diffraction studies. We find that the nucleotide binding steps, the ATP-isomerization step, and the cross-bridge detachment step were minimally affected by the compression. Our results indicate that the rate constant of the reverse power stroke step (k-4) decreases with mild compression (0-6.3% dextran), presumably because of the stabilization of the attached cross-bridges in the AM*DP state. We also found that the rate constant of the power stroke step (k4) decreases with higher compression (> 6.3% dextran), presumably because of increased difficulty in performing the power stroke reaction. Our results further show that the association constant (K5) of phosphate to cross-bridges is not changed with compression. The ATP hydrolysis rate declined almost linearly with an increase in the dextran concentration. This observation indicates that the rate limiting step is also affected by the lattice spacing change so that the associated rate constant (k6) becomes progressively less with compression.

Adenosine Diphosphate↗
PubMed1983

A comparison of order and orientation of crossbridges in rigor and relaxed muscle fibres using fluorescence polarization.

Information has been obtained concerning the spatial disposition of the fluorescent reagent 5-(iodoacetamidoethylaminonaphthalene)-1-sulphonic acid bound covalently to muscle proteins in chemically skinned fibres of rabbit psoas muscle, using a novel time-gated fluorescence detection system to reject scattered incident light selectively. The results are consistent with a model of muscle crossbridge organization in which a particular crossbridge axial angle is strongly favoured in the rigor state. The structure in relaxation is less well ordered, but the favoured axial angle appears to be very close to that in rigor. This conclusion does not depend upon which of the models of crossbridge organization considered here is chosen, and is essentially unchanged if results obtained using a different fluorophore are analysed in the same way.

Animals↗
PubMed1967

Variations of the contractile apparatus in smooth and striated muscles. X-ray diffraction studies at rest and in contraction.

Structural information is presented for three muscle systems-mammalian smooth muscle at rest and partially active, living toad striated muscle at rest and contracting, and glycerinated rabbit psoas muscle under various conditions of pH and ionic environment. In the smooth muscle no evidence of organized myosin filaments has been found. In the striated muscle the myosin-to-actin distance can vary widely, according to sarcomere length and to muscle treatment, both at rest and during contraction. In the discussion it is suggested that muscle should be considered as a colloidal system and that there need not necessarily be any chemical bonding (cross-linking) involved in the contractile process.

Action Potentials↗
PubMed1991

Abscess of the iliopsoas muscle diagnosed by magnetic resonance imaging and ultrasonography.

We have reported a case of abscess of the iliopsoas muscle, in which a limp and hip pain pointed toward pathology of the hip. The diagnosis in such cases may be difficult unless there is close attention to the clinical history and a good physical examination is obtained. One ultrasonographic examination of the hip in such a patient, subtle differences between the iliopsoas muscles should alert the radiologist to examine the psoas muscle. Ultrasonography is instrumental in demonstrating the solid or cystic nature of the iliopsoas mass, while MRI depicts the extent and proximity of adjacent organs. Once an iliopsoas abscess is diagnosed, treatment includes parenteral antibiotics and drainage.

Abscess↗
PubMed1988

The inhibition of rabbit skeletal muscle contraction by hydrogen ions and phosphate.

1. The effects of phosphate and protons on the mechanics and energetics of muscle contraction have been investigated using glycerinated rabbit psoas muscle. 2. Fibres were fully activated by addition of Ca2+ (pCa 4-5) at 10 degrees C. The velocities of contraction were measured in isotonic load clamps, and the velocities of unloaded fibres were measured by applying a series of step changes in fibre length. Fibre ATPase activity was monitored using an enzyme system to couple ADP production to reduced nicotinamide-adenine dinucleotide (NADH) and measuring the depletion of NADH by optical density. 3. At pH 7.0 and 3 mM-phosphate, isometric tension (P0) was 13.2 +/- 0.9 N/cm (mean +/- S.E.M., n = 10 observations), the maximum contraction velocity (Vmax) was 1.63 +/- 0.05 lengths/s (n = 5) and the ATPase activity was 1.27 +/- 0.12 s-1 myosin head-1 (n = 35). Increasing phosphate from 3 to 20 mM at pH 7.0 does not affect Vmax, causes a small decrease in the ATPase activity (15-20%) and decreases P0 by approximately 20%. Changing pH from 7 to 6 at 3 mM-phosphate decreases P0 by 45% and both Vmax and ATPase activity by 25-30%. The effects of changing both pH and phosphate were approximately additive for all parameters measured. The inhibition of these parameters by low pH and high concentration of phosphate was reversible. 4. The force-velocity relation was fitted by the Hill equation using a non-linear least-squares method. The value of the parameter which describes the curvature, a/P0, was 0.20. The curvature of the force-velocity relation was not changed by addition of phosphate or by changes in pH. 5. These data provide information on both the kinetics of the actomyosin interaction and on the process of muscle fatigue. The data are consistent with models of cross-bridge kinetics in which phosphate is released within the powerstroke in a step involving a rapid equilibrium between states. The inhibition by protons is more complex, and may involve less specific effects on protein structure. 6. During moderate fatigue of living skeletal muscle, MgATP concentration is known to remain approximately constant at 4 mM, phosphate to increase from 3 to 20 mM, and protons from 0.1 to 1 microM. The data suggest that much of the inhibition of P0 observed during moderate fatigue can be explained by the increased levels of phosphate and protons, and that much of the inhibition of fibre Vmax and ATPase activity can be explained by the increase in protons.

Adenosine Triphosphatases↗
PubMed1977

Appendicitis presenting as a swollen thigh.

A case of acute appendicitis presenting as an abscess in the thigh with associated gas is described. The tracking of the pus down the psoas muscle is stressed, and its association with the psoas sign is noted.

Abscess↗
PubMed1986

The ultrastructural location of C-protein, X-protein and H-protein in rabbit muscle.

Purified antibodies to the thick filament accessory proteins, C-protein, X-protein and H-protein, have been used to label fibres of three rabbit muscles, psoas (containing mainly fast white fibres), soleus (containing mainly slow red fibres) and plantaris (a muscle of mixed fibre type) and their location has been examined by electron microscopy. These accessory proteins are present on one or more of a set of eleven transverse stripes about 43 nm apart that have been observed previously in each half A-band. Each protein has a limited set of characteristic distributions. H-protein is present on stripe 3 (counting from the M-line) in the majority of psoas fibres but is absent in soleus and plantaris muscle. C-protein can occur on stripes 4-11 (the commonest pattern seen in psoas); on stripes 5-11 (in psoas and plantaris); on stripes 3 together with stripes 5-11 (in plantaris); or on none (in red fibres of all three muscles). X-protein can occur on stripes 3-11 in the red fibres of all three muscles; on stripe 4 only (in psoas and plantaris); on stripes 3 and 4 (in psoas and plantaris) or on none. Stripes labelled with anti-X are wider than those labelled with anti-C and consist of a doublet with an internal spacing of 16 nm. The patterns for the three accessory proteins, while overlapping, are in no case identical; this suggests the proteins do not simply substitute for one another. The precise axial positions of the anti-C labelled stripes differ from those of the anti-X stripes; the anti-X stripes lie about 8-9 nm further from the M-line than the corresponding anti-C stripes. This implies that the inner member of an X-protein doublet lies in a very similar position to a C-protein stripe. The anti-H labelled stripe seen in most psoas fibres lies 14 nm nearer the M-line than stripe 3 of the anti-X labelled array in psoas red fibres and is staggered from a continuation of the C-protein array by about 4 nm. The labelling patterns were constant within a fibre and suggest a very precise assembly mechanism. The number of classes of fibre, as defined by the accessory proteins present and their arrangement, exceeds the number of fibre types presently recognized.

Animals↗
PubMed2005

Relief of internal snapping hip syndrome in a marathon runner after chiropractic treatment.

OBJECTIVE: To discuss the assessment, diagnosis and chiropractic management of a patient with sacroiliac joint dysfunction (SIJ) complicated by psoas major snapping hip syndrome (coxa saltans interna). CLINICAL FEATURES: A 32-year-old male marathon runner experienced low-back and left hip pain without radiation accompanied by a "popping" in the anterior hip. He ran approximately 100 to 150 km/wk for the prior 3 years. He had stopped running for the previous 3 weeks because of worsening and consistent pain. INTERVENTION AND OUTCOME: Treatment consisted of side posture SIJ "diversified" manipulation and myofascial release to the psoas muscle twice weekly for 2 weeks. The patient was also taught proprioceptive neuromuscular facilitation exercises of the psoas and iliotibial band muscles. He was instructed to substitute swimming instead of running on a daily basis. Reassessment at 3 weeks found the patient without pain in his hip or back and no clicking or popping in his left hip. CONCLUSION: Clinicians should consider that runners who present with coexisting SIJ dysfunction and internal snapping hip syndrome may benefit from the combined management of both conditions.

Adult↗
PubMed1990

The influence of the rate of rigor state development on its tension in single muscle fibre.

The rigor tension and stiffness of glycerinated fibres from rabbit psoas muscle were found to vary markedly in dependence on the rate of substitution of the solutions in the experimental chamber. The maximum value of rigor tension, which is close to that activated by Ca2+ with pCa4, was obtained at the slow development of rigor in the absence of Ca2+ ions. The observed dependence is assumed to be due to the different degrees of removal of the 'slack' in fibres, which may be contributed by compliant ends of the preparation. A new method allowing to obtain rather reproducible values of rigor tension is proposed.

Adenosine Triphosphate↗
PubMed1988

Effect of diabetes on guanine nucleotide exchange factor activity in skeletal muscle and heart.

The present study examined the effects of diabetes and insulin treatment of diabetic rats on the activity of the protein synthesis initiation factor, the guanine nucleotide exchange factor. In extracts from gastrocnemius and psoas muscles from two-day diabetic rats, guanine nucleotide exchange factor activity was reduced to 80% and 67% of control values, respectively. Insulin treatment (2 h) restored guanine nucleotide exchange factor activity to control values in both muscles. In contrast, guanine nucleotide exchange factor activity was unchanged in extracts from either soleus muscle or heart from diabetic rats compared to controls. Also, insulin treatment did not increase guanine nucleotide exchange factor activity in extracts from soleus and heart. The results suggest that the diabetes-induced impairment in peptide-chain initiation in fast-twitch skeletal muscle (i.e. gastrocnemius and psoas) is related to an inhibition of guanine nucleotide exchange factor activity and that slow-twitch muscle is spared from the effect on initiation due to the preservation of guanine nucleotide exchange factor activity.

Animals↗
PubMed1997

Combination of fatal digoxin poisoning with endocardial fibroelastosis.

This is the first report in the forensic literature of a combination of fatal digoxin poisoning with endocardial fibroelastosis (EFE). Typical morphological features of EFE as the cause of clinically diagnosed cardiomyopathy were present in the autopsy of a 3-year-old girl, including cardiac hypertrophy and marked thickening of the left-sided endocardium, consisting of numerous elastic and collagenic fibres. After exclusion of cardiac and cerebral causes of death, accidental digoxin intoxication was proved. Postmortem toxicological analyses by fluorescence polarization immunoassay (FPIA) disclosed digoxin levels of 71 micrograms/kg (femoral vein blood), 77 micrograms/kg (cardiac blood), 255 and 221 micrograms/kg (cardiac muscle of the right and left chamber), 163 micrograms/kg (psoas muscle), 91 micrograms/kg (lung), 222 micrograms/kg (liver) and 520 micrograms/kg (kidney). The results are compared with the antemortem digoxin concentration of 39 ng/ml serum. The case is discussed from its unusual morphological and toxicological aspects, with special consideration of possible medical malpractice.

Cardiotonic Agents↗
PubMed2001

Geometric parameters of the in vivo tissues at the lumbosacral joint of young Asian adults.

STUDY DESIGN: Magnetic resonance images (MRIs) were used to determine the geometry of the tissues studied. OBJECTIVE: To investigate the geometric parameters of tissues around the lumbosacral joint. SUMMARY OF BACKGROUND DATA: Cross-sectional area (CSA), moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1), which are important in the study of spinal mechanics and models for the investigation of low back pain. It was insufficient information to describe the relative dimension of spinal tissues except muscles around the lumbar spine. METHODS: MRIs from eight asymptomatic young Taiwanese male adults were collected to present CSA, moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1). Four pairs of trunk muscles, erector spinae, rectus abdominis, abdominal oblique externus, and psoas muscles, ligamentum flavum, and facet joints at the bilateral sides were studied. RESULTS: Spinal tissues at the level of lumbosacral joint were determined. The CSAs of the spinal elements at the L5-S1 normalized by the CSA of trunk ranged from 5.42% (the erector spinae) to 0.14% (the ligamentum flavum). The moment arm of the spinal elements relative to the trunk width and depth ranged from 40.91% (rectus abdominis at the y direction) to 0.38% (ligamentum flavum at the x direction). The profile of geometric elements of lumbosacral joint in the Asian male subjects was similar to the data collected from the white population. The data also showed that right-left symmetry in the aforementioned dimension. CONCLUSION: Normalized data of the CSA, moment arm, and line of action of the spinal tissues at the L5-S1 joint were reported in vivo through the MRI techniques. The profile of geometric elements of lumbosacral joint in the Asian male subjects did not differ from the white population. In addition to muscles, the geometry of facet joint and ligament was determined, which would be important to the calculation of force distribution on the lumbosacral joint.

Adult↗
PubMed1985

Fatty acid abnormalities in cystic fibrosis.

Fatty acids were measured by gas chromatography in lipid extracts of plasma and tissues obtained from three categories of 46 patients with cystic fibrosis. Low levels of the major essential fatty acid linoleate were found in plasma total lipids of patients who had malabsorption but not in those without evidence of steatorrhea. Circulating arachidonic acid was only slightly decreased, and the unusual triene reflecting pathologically altered fatty acid metabolism (20:3 omega 9) was generally not detected, nor was the triene/tetraene ratio abnormal except for in two patients. There was no correlation between plasma linoleate and age, clinical severity score, or vitamin E status. Decreased linoleate did correlate with two indices of malabsorption, namely plasma carotene (r = 0.64) and fecal fat excretion (r = 0.76). Our data therefore indicate that the abnormality in linoleate is associated with (secondary to) malabsorption of dietary fat despite pancreatic enzyme replacement therapy and consumption of a regular diet. The frequency of this alteration was determined to be quite high in 40 patients with steatorrhea, 85% of whom showed values below the lower limit of normal for plasma linoleate. It was of interest to find markedly decreased levels of linoleate in adipose tissue, cardiac muscle, and lung and lesser reductions in liver and psoas muscle taken at autopsies. Tissue arachidonic acid percentage was normal, however, and 20:3 omega 9 was rarely present. Thus, the physiological significance of this common abnormality in CF patients with malabsorption remains to be determined.

Adipose Tissue↗
PubMed1995

Sliding distance per ATP molecule hydrolyzed by myosin heads during isotonic shortening of skinned muscle fibers.

We measured isotonic sliding distance of single skinned fibers from rabbit psoas muscle when known and limited amounts of ATP were made available to the contractile apparatus. The fibers were immersed in paraffin oil at 20 degrees C, and laser pulse photolysis of caged ATP within the fiber initiated the contraction. The amount of ATP released was measured by photolyzing 3H-ATP within fibers, separating the reaction products by high-pressure liquid chromatography, and then counting the effluent peaks by liquid scintillation. The fiber stiffness was monitored to estimate the proportion of thick and thin filament sites interacting during filament sliding. The interaction distance, Di, defined as the sliding distance while a myosin head interacts with actin in the thin filament per ATP molecule hydrolyzed, was estimated from the shortening distance, the number of ATP molecules hydrolyzed by the myosin heads, and the stiffness. Di increased from 11 to 60 nm as the isotonic tension was reduced from 80% to 6% of the isometric tension. Velocity and Di increased with the concentration of ATP available. As isotonic load was increased, the interaction distance decreased linearly with decrease of the shortening velocity and extrapolated to 8 nm at zero velocity. Extrapolation of the relationship between Di and velocity to saturating ATP concentration suggests that Di reaches 100-190 nm at high shortening velocity. The interaction distance corresponds to the sliding distance while cross-bridges are producing positive (working) force plus the distance while they are dragging (producing negative forces). The results indicate that the working and drag distances increase as the velocity increases. Because Di is larger than the size of either the myosin head or the actin monomer, the results suggest that for each ATPase cycle, a myosin head interacts mechanically with several actin monomers either while working or while producing drag.

Adenosine Diphosphate↗
PubMed1965

Contractility and ultrastructure in glycerol--extracted muscle fibers. II. Ultrastructure in resting and shortened fibers.

Glycerol-extracted rabbit psoas muscle fibers were examined by electron microscopy both before and after ATP-induced isotonic shortening. Ultrastructural changes were correlated with the initial sarcomere length and the degree of shortening. The ultrastructural appearance of the resting fiber at rest length was identical with that described by H. E. Huxley and Hanson. At sarcomere lengths greater than 3.7 to 3.8 micro, the A and I filaments were detached and separated by a gap. The presence of "gap" filaments was confirmed, and evidence is presented which indicates that these filaments form connections between the ends of the A and I filaments. Shortening from initial sarcomere lengths at which the filaments overlapped took place through sliding of the filaments. If shortening was initiated from sarcomere lengths at which there was a gap, a narrowing of the I band was brought about by a curling of the I filaments at the boundary between the A and I bands. No evidence could be found that the I filaments moved into the A band.

Animals↗