RESUMEN

OBJECTIVE: To investigate the reliability of a new radiographic measurement of axial rotation and lateral bending on anterior-posterior cervical views by using a computer and sonic digitizer. DESIGN: A blind, repeated-measure design was used. Anteroposterior cervicothoracic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and 1 week later the films were randomized for a second run. SETTING: Private, primary-care chiropractic clinic. MAIN OUTCOME MEASURES: The interclass and intraclass correlation coefficients (ICC) for intraexaminer and interexaminer reliability were calculated from measurements on radiographs for determining axial rotations (Ry) and lateral bending (Rz) of C3 to T3. RESULTS: When the new axial rotation method was applied to small rotations of a C3 plastic model, the average error was less than 1 degrees. For the calculations of axial rotation (Ry), the ICC values were in the good to excellent range. For axial rotation, the intraclass correlation coefficients were ICCs > or =0.78, and the interclass correlation coefficients were ICCs > or =0.67. For lateral flexions (Rz) of C3 to T3, all intraclass and interclass correlation coefficients were in the excellent range (ICCs > 0.87). CONCLUSIONS: Methods of calculating axial rotations in the spine have been reported for large angles (5 degrees to 30 degrees ) but not for smaller angles. A new method for determining axial rotations of the cervical segments on AP views, based on the chord across the arc displaced by the spinous-lamina junction, had reliability (ICC values) in the good to excellent range. Compared with measured rotations of a C3 model (-5 degrees to +5 degrees ), the new method had an average error of less than 1 degrees and approximately 11.5%. The reliability for the axial rotation measurements was in the good to excellent range, and the lateral bending measurements were all in the excellent range.

Asunto(s)

RESUMEN

Previous studies identified a prostaglandin E(2) (PGE(2)) receptor in the salivary glands of partially fed female lone star ticks, Amblyomma americanum (L.). In the present studies, protein secretion from dispersed salivary gland acini was shown to be specific for PGE(2), as compared with PGF(2alpha) or the thromboxane analog U-46619, in accordance with their respective binding affinities for the PGE(2) receptor. Furthermore, the selective PGE(2) EP1 receptor agonist, 17-phenyl trinor PGE(2), was as effective as PGE(2) in stimulating secretion of anticoagulant protein. Calcium ionophore A-23187 (1 to 100 microM) stimulated secretion of anticoagulant protein in a dose-dependent manner but the voltage-gated Ca(2+)-channel blocker verapamil (1 to 1000 microM) and the receptor-mediated Ca(2+)-entry antagonist, SK&F 96365 (1 and 10 microM), and 5mM ethylene glycol bis(beta-aminoethyl ether)-N,NN', N'-tetraacetic acid (EGTA) had no appreciable effect on inhibiting PGE(2)-stimulated secretion of anticoagulant protein. PGE(2) (0.1 microM) and the non-hydrolyzable analog of guanosine triphosphate (GTP), GTPgammaS (10 microM), directly activated phospholipase C (PLC) in a membrane-enriched fraction of the salivary glands after PLC was first incubated with the PGE(2) EP1 receptor antagonist AH-6809, which presumably antagonized endogenous PGE(2) (0.3 microM) in the broken-cell-membrane-enriched fraction. TMB-8, an antagonist of intracellular inositol trisphosphate (IP(3)) receptors, inhibited PGE(2)-stimulated secretion. The results support the hypothesis that PGE(2) stimulates secretion of tick salivary gland protein via a phosphoinositide signaling pathway and mobilization of intracellular Ca(2+).

Asunto(s)

RESUMEN

OBJECTIVE: To investigate the reliability of a radiographic measurement procedure that uses a computer and sonic digitizer to determine projected spinal displacements from an ideal normal position. DESIGN: A blind, repeated-measure design was used. Anteroposterior lumbopelvic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and the films were randomized for a second run. SETTING: Private, primary-care chiropractic clinic. MAIN OUTCOME MEASURES: The angle of the sacral base in comparison to a true horizontal line (horizontal base angle), lumbodorsal angle, lumbosacral angle, and the thoracic translational displacement from true vertical determined as the perpendicular distance from the center of T12 to a vertical axis line drawn from the center of the S1 spinous process cephalad and parallel to the lateral edge of the x-ray film. RESULTS: Intraexaminer reliability for the (a) horizontal base angle was .72 to .94, with confidence intervals included in the range of .52 to .97; (b) lumbodorsal angle was .90 to .96, with confidence intervals in the range of .82 to .98; (c) lumbosacral angle was .84 to .96, with confidence intervals in the range of .72 to .98, and (d) thoracic translational displacement from vertical was .95 to.97, with confidence intervals included in the range of .91 to .99. Interexaminer reliability for the three examiners ranged from .71 to .97. CONCLUSIONS: Measures similar to those described in this study are commonly used to measure and categorize spinal displacements from true vertical alignment (ie, scoliosis measurements). Most patient assessment methods used in chiropractic have poor or unknown reliability. The one possible exception to this rule is spinal displacement analysis performed on radiographs. In chiropractic, intraclass correlation coefficients values greater than .70 are considered accurate enough for use in clinical and research applications. The measures tested here would fit within these guidelines of reliability. Establishing reliability is an important first step in evaluating these measures so that future studies of validity may be undertaken.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

There are few complications associated with intravenous regional anaesthesia but convulsions with loss of consciousness induced by local anaesthetic toxicity may result in pulmonary aspiration. In many hospitals, patients are fasted prior to the procedure although such a delay would be of little value if gastric emptying was inhibited following painful injury. Utilizing the kinetics of paracetamol absorption, we investigated the rate of gastric emptying in patients sustaining a Colles' fracture within the previous 4 h. Post-manipulation control values were obtained at their first out-patient attendance. There was no statistically significant difference in the rate of gastric emptying. Since gastric emptying is not delayed by a recent Colles' fracture, the simple precaution of fasting patients prior to intravenous regional anaesthesia should reduce the risk of pulmonary aspiration.

Asunto(s)

RESUMEN

Most current textbooks of cell biology and histology use the steric blocking model to describe the protein mechanism by which vertebrate striated muscle contraction is regulated. Evidence accumulated in the past decade, however, reveals the regulation of muscle contraction to be far more complex than this model predicts.

Asunto(s)

RESUMEN

Using the peroxidase-antiperoxidase staining technique with monoclonal and polyclonal antibodies against actin, we found that, in beta,beta'-iminodipropionitrile (IDPN)-treated axons, actin immunoreactivity was codistributed with segregated microtubules and membranous organelles in the central region and excluded from the peripheral axoplasm occupied by neurofilaments. Actin immunoreactivity was also present in the subaxolemmal region. Fast axonal transport is localized in the central region of the IDPN axon (Papasozomenos et al., 1982a). As both microtubules and actin are present in the central region of IDPN axons, a possible role of actin in fast axonal transport warrants further investigation.

Asunto(s)

Asunto(s)

RESUMEN

DNAase I, an endonuclease which interacts with G-actin, also affects tropomyosin polymerization. With chicken pectoralis or bovine cardiac ventricle tropomyosin, DNAase I both prevents tropomyosin from polymerizing and disrupts already formed tropomysin filaments. DNAase I and filament tropomyosin can also form a precipitable complex. In the electron microscope, the complex is observed as irregularly margined stellate-shaped structures with a maximum size of 9 micron. Isolated DNAase I-tropomyosin stellate complex consists of a 2:1 molar ratio of DNAase I and tropomyosin, suggesting that each tropomyosin subunit can bind DNAase I.

Asunto(s)

RESUMEN

Tropomyosin polymerization is inhibited by DNAse I, an endonuclease which also interacts with G-actin. A 1:4 molar ratio of DNAse I to adult chicken pectoralis muscle tropomyosin almost completely prevents the increased viscosity of tropomyosin under polymerizing ionic conditions. While G-actin binding to DNAse I inhibits the DNAse I hydrolysis of DNA, tropomyosin does not affect this enzymatic activity. G-actin-DNAse I interaction is also not altered by tropomyosin.

Asunto(s)

RESUMEN

Seven monoclonal antibodies specific for mammalian beta-tubulin demonstrate the microtubule cytoskeleton of Toxoplasma gondii and Leishmania donovani by indirect immunofluorescence microscopy. Immunoblots of T. gondii and L. donovani proteins separated by SDS polyacrylamide gel electrophoresis confirm the specificity of the monoclonal antibodies for tubulin. Differential staining of flagellar and subpellicular microtubule populations was not seen in L. donovani with these antibodies. All seven antibodies also detected the subpellicular microtubules of T. gondii, but the polar ring and conoid of this organism was not visualized by any of them. This technique provides a rapid and specific way to assess microtubular organization in whole organisms.

Asunto(s)

RESUMEN

A progestogen (norethisterone) and a dopamine antagonist (sulpiride) were given alone and in combination to volunteers to examine their effects on excretion of ovarian steroids. Compared with non-treatment cycles (n = 15), contraception with a progestogen alone (n = 10) was associated with increased excretion of oestrone and partial suppression of excretion of pregnanediol, suggesting partial luteinization of unruptured follicles. By contrast, the combination of norethisterone and sulpiride (n = 9) suppressed both ovarian steroids to basal values, the suppression being even greater than with sulpiride alone (n = 5). These results suggest that a combination of a progestogen with a dopamine antagonist might have a role in contraception.

Asunto(s)

RESUMEN

We have examined the distribution of microtubule-associated protein 2 (MAP2) in the lumbar segment of spinal cord, ventral and dorsal roots, and dorsal root ganglia of control and beta,beta'-iminodipropionitrile-treated rats. The peroxidase-antiperoxidase technique was used for light and electron microscopic immunohistochemical studies with two monoclonal antibodies directed against different epitopes of Chinese hamster brain MAP2, designated AP9 and AP13. MAP2 immunoreactivity was present in axons of spinal motor neurons, but was not detected in axons of white matter tracts of spinal cord and in the majority of axons of the dorsal root. A gradient of staining intensity among dendrites, cell bodies, and axons of spinal motor neurons was present, with dendrites staining most intensely and axons the least. While dendrites and cell bodies of all neurons in the spinal cord were intensely positive, neurons of the dorsal root ganglia were variably stained. The axons of labeled dorsal root ganglion cells were intensely labeled up to their bifurcation; beyond this point, while only occasional central processes in dorsal roots were weakly stained, the majority of peripheral processes in spinal nerves were positive. beta,beta'-Iminodipropionitrile produced segregation of microtubules and membranous organelles from neurofilaments in the peripheral nervous system portion and accumulation of neurofilaments in the central nervous system portion of spinal motor axons. While both anti-MAP2 hybridoma antibodies co-localized with microtubules in the central nervous system portion, only one co-localized with microtubules in the peripheral nervous system portion of spinal motor axons, while the other antibody co-localized with neurofilaments and did not stain the central region of the axon which contained microtubules. These findings suggest that (a) MAP2 is present in axons of spinal motor neurons, albeit in a lower concentration or in a different form than is present in dendrites, and (b) the MAP2 in axons interacts with both microtubules and neurofilaments.

Asunto(s)

Asunto(s)

RESUMEN

The electrophoretic pattern of the large microtubule-associated protein, MAP2, changes during rat brain development. Immunoblots of NaDodSO4 extracts obtained from the cerebral cortex, cerebellum, and thalamus at 10-15 days after birth reveal only a single electrophoretic species when probed with any of three MAP2 monoclonal antibodies. By contrast, adult MAP2 contains two immunoreactive species, MAP2a and MAP2b. The single band of MAP2 from immature brain electrophoretically comigrates with adult MAP2b. Between postnatal days 17 and 18, immature MAP2 simultaneously resolves into two species in both the cerebellum and cerebral cortex. Immunoblots of NaDodSO4 extracts from spinal cord demonstrate the adult complement of MAP2 by day 10, indicating that MAP2 does not change coordinately throughout the entire central nervous system. In vitro cAMP-dependent phosphorylation of immature MAP2 causes a band split reminiscent of that seen during brain development in vivo. The possibility that the developmentally regulated changes observed in MAP2 during brain maturation are due to timed phosphorylation events is discussed.

Asunto(s)

RESUMEN

The distribution and subcellular localization of tubulin and MAP2 in brain tissue were analyzed by immunocytochemistry with monoclonal hybridoma antibodies prepared against Chinese hamster brain tubulin and MAP2. We examined three anti-tubulin hybridoma antibodies (Tu3B, Tu9B, Tu12) specific for beta-tubulin, and two anti-MAP2 hybridoma antibodies (AP9,AP13). The specificity of each of the monoclonal antibodies was characterized by staining nitrocellulose electrophoretic blots of SDS-polyacrylamide gels of whole brain or hippocampal extracts. Each hybridoma antibody bound only its respective antigen in these preparations. Polyclonal antisera against tubulin were also examined. Sections reacted with antisera against tubulin or monoclonal antibodies against beta-tubulin revealed a wide variety of stained cellular compartments. The reaction product was found to decorate dendritic and axonal microtubles in neurons; glial cells were also stained. MAP2 immunoreactivity was found only in neurons. In the case of one of the monoclonal antibodies (AP9), staining was preferentially associated with dendritic processes. However, light but significant staining of axonal processes was seen with AP13. Within dendrites, MAP2 was found associated with dendritic microtubules and postsynaptic densities (psd), both in shaft and spine synapses. In addition, strong immunoreactivity for MAP2 was found within the cytoplasm of dendritic spines. There was little or no immunoreactivity for tubulin in the spine cytoplasm, although the psd was stained. The localization of MAP2 in dendritic spines and in the psd suggests that this protein may have a biological role independent of its association with microtubules. The observations on differential staining of the hybridoma antibodies against MAP2 suggest that there may be distinct subtypes or states of MAP2 within neurons.

Asunto(s)

RESUMEN

Monoclonal antibodies to adult quail breast muscle myosin (QBM) have been prepared and characterized using a solid phase enzyme linked immunosorbent assay and immunoblot procedures. One antibody (QBM-1) is directed against an epitope in the rod portion of the myosin heavy chain while another (QBM-2) binds exclusively to a conserved portion of the two alkali light chains of fast muscle myosin. Both of these antibodies cross-react with myosin from myotubes cultured in vitro but do not recognize non-muscle myosin. The application of these antibodies to the study of myogenesis is discussed.

Asunto(s)

RESUMEN

To determine whether dendritic spines contain actin, we evaluated the immunocytochemical localization of actin in the hippocampal formation and cerebral cortex of the rat. Monoclonal hybridoma antibodies were prepared against adult quail breast muscle actin. The culture supernatant of two cell lines (QAB1 and QAB2) was examined. Both antibodies bound only actin in crude brain homogenates, and neither exhibited species specificity. Electron microscopic analyses of sections reacted with QAB1 revealed staining of postsynaptic densities and dendritic microtubules but little staining of the cytoplasmic compartment of spines. However, sections reacted with QAB2 exhibited staining at the cytoplasmic compartment of spines as well as the sites stained by QAB1. We also evaluated the immunocytochemical distribution of beta-tubulin and high molecular weight microtubule-associated protein (MAP2) utilizing monoclonal antibodies. MAP2 was found in the dendritic spine as well as in the parent dendrite. However, beta-tubulin was found only in the postsynaptic density and in the microtubules of the parent dendrite. The combined results indicate that actin is present in the spine along with MAP2 and that there is a difference in the actin (or the state of actin) in the spine in comparison with other neuronal compartments.

Asunto(s)