Muscarinic acetylcholine receptors in Torpedo electric organ: effect of guanine nucleotides

The effect of guanine nucleotides on the binding properties of presynaptic muscarinic receptors has been studied in a membrane preparation from the electric organ of Torpedo marmorata by measuring the competitive displacement of the radiolabelled antagonist, [3H]quinuclidinyl benzilate, by nonradioactive muscarinic ligands. The binding of the antagonists, atropine, scopolamine and pirenzepine was to a single class of sites [slope factors (pseudo Hill coefficients) close to 1] and was unaffected by 0.1 mM GTP. The binding of the N-methylated antagonists, N-methylatropine and N-methyl-scopolamine was more complex (slope factors less than 1) but also insensitive (N-methylatropine) to 0.1 mM GTP. Agonist binding was complex and could be resolved into two binding sites with relatively high and low affinities. The proportion of high-affinity sites varied with the nature of the agonist (15-80%). Agonist binding was depressed by 0.1 mM GTP, and the order of sensitivity was oxotremorine-M greater than carbamoylcholine greater than muscarine greater than acetylcholine greater than arecoline greater than oxotremorine. The binding of pilocarpine, a partial agonist, was unaffected by GTP. With carbamoylcholine as a test ligand the GTP effect on agonist binding was half-maximal at 12 microM. GDP and guanylylimidodiphosphate produced comparable inhibition of carbamoylcholine binding, but GMP and cyclic GMP were ineffective, as were various adenine nucleotides. Analysis of agonist binding in terms of a two-site model indicates that the predominant effect of guanine nucleotides is to reduce the number of sites of higher affinity.     

Dosimetry of rhenium-186-labeled monoclonal antibodies: methods, prediction from technetium-99m-labeled antibodies and results of phase I trials

Rhenium-186 is a beta-emitting radionuclide that has been studied for applications in radioimmunotherapy. Its 137 keV gamma photon is ideal for imaging the biodistribution of the immunoconjugates and for obtaining gamma camera data for estimation of dosimetry. Methods used for determining radiation absorbed dose are described. We have estimated absorbed dose to normal organs and tumors following administration of two different 186Re-labeled immunoconjugates, intact NR-LU-10 antibody and the F(ab')2 fragment of NR-CO-02. Tumor dose estimates in 46 patients varied over a wide range, 0.4-18.6 rads/mCi, but were similar in both studies. Accuracy of activity estimates in superficial tumors was confirmed by biopsy. Prediction of 186Re dosimetry from a prior 99mTc imaging study using a tracer dose of antibody was attempted in the NR-CO-02 (Fab')2 study. Although 99mTc was an accurate predictor of tumor localization and the mean predicted and observed radiation absorbed doses to normal organs compared favorably, 186Re dosimetry could not be reliably predicted in individual patients. The methods described nevertheless provide adequate estimates of 186Re dosimetry to tumor and normal organs.     

Direct vs indirect blood pressure at rest and during isometric exercise in normal subjects

Systolic and diastolic blood pressures were measured by intraarterial means and by auscultation. Comparisons were made with simultaneously determined intraarterial catheter and auscultation measurements. Five healthy males were measured at rest and during handgrip and deadlift isometric exercises, utilizing small and large muscle mass. The data suggest that indirect systolic blood pressure is highly correlated with the direct method at rest, during handgrip and deadlift (0.8, 0.9 and 0.91 respectively) isometric exercises. Indirect diastolic blood pressure correlates well with intraarterial at rest (0.7) and during the isometric handgrip bout which utilized small muscle mass (0.8). As for the deadlift manoeuvre, the correlation coefficients between the indirect and direct methods were low. These results suggest that when utilizing large muscle mass during isometric deadlift exercise, the indirect method is not valid for assessment of diastolic blood pressure.     

A G-protein-coupled 130 kDa phospholipase C isozyme, PLC-beta 4, from the particulate fraction of bovine cerebellum

A 130 kDa PLC isozyme was purified from the particulate fraction of bovine cerebellum. This PLC was recognized by a polyclonal antiserum generated against the purified 97 kDa PLC-beta 4. Reconstitution of the purified 130 kDa PLC with the membranes of C6 Bu-1 cells in the presence of GTP gamma S or AlF4- resulted in PLC activation as well as the association of PLC with the membranes. Both the association and activation were revoked when the membrane was washed with 2 M KCl. The 97 kDa PLC-beta 4 did not associate with membranes. These data suggest that the 130 kDa PLC is the intact form of PLC-beta 4 the activity of which is likely to be regulated by a G-protein on the membrane.     

Cardiac geometry and mass changes associated with pacing-induced cardiomyopathy in the dog

Olfactomedin is the major glycoprotein of the extracellular mucous matrix of frog olfactory neuroepithelium. It is responsible for the primary architecture of this extracellular matrix by forming via intermolecular disulfide bonds polymers, which are covered with evenly spaced carbohydrate groups. To study glycosylation of olfactomedin, we raised antibodies against the mature protein and antibodies against a region adjacent to an N-linked glycosylation site near its amino terminus. The latter antibodies cannot bind when this site is glycosylated and reveal precursors of olfactomedin in the perinuclear regions of Bowman's glands. In contrast, antiserum against the mature protein stains acinar regions of glands and the ciliary surface. Enzymatic deglycosylation of olfactomedin shows stepwise removal of carbohydrate and reveals a 51-kDa deglycosylated form. Our results indicate that, prior to secretion, most, if not all, of the six potential N-linked glycosylation sites of olfactomedin are glycosylated with carbohydrate moieties of about 8-10 sugar residues.     

A comparison of intra- and interpersonal interlimb coordination: coordination breakdowns and coupling strength

Intra- and interpersonal interlimb coordination of pendulums swung from the wrist was investigated. For both kinds of coordination, the steady state and breakdown of bimanual rhythmic coordination as indexed by the time series of the relative phase angle phi were studied under the manipulation of coordination mode, frequency of oscillation, and the difference in the eigenfrequencies (preferred tempos) of the individual oscillating limbs. The properties observed for both intra- and interpersonal coordination were those predicted by a dynamical model of rhythmic coordination that considers the coordinated limbs coupled to be nonlinear oscillators. Using a regression method, the coupling strengths of the coupled system were recovered. As predicted by the dynamical model, the strength of the dynamic was generally greater for the in-phase than the anti-phase mode and decreased with increasing frequency. Further, the strength of the interpersonal interlimb coupling was weaker than that of intrapersonal interlimb coupling.     

A comparison of active and simulated chiropractic manipulation as adjunctive treatment for childhood asthma

BACKGROUND: Chiropractic spinal manipulation has been reported to be of benefit in nonmusculoskeletal conditions, including asthma. METHODS: We conducted a randomized, controlled trial of chiropractic spinal manipulation for children with mild or moderate asthma. After a three-week base-line evaluation period, 91 children who had continuing symptoms of asthma despite usual medical therapy were randomly assigned to receive either active or simulated chiropractic manipulation for four months. None had previously received chiropractic care. Each subject was treated by 1 of 11 participating chiropractors, selected by the family according to location. The primary outcome measure was the change from base line in the peak expiratory flow, measured in the morning, before the use of a bronchodilator, at two and four months. Except for the treating chiropractor and one investigator (who was not involved in assessing outcomes), all participants remained fully blinded to treatment assignment throughout the study. RESULTS: Eighty children (38 in the active-treatment group and 42 in the simulated-treatment group) had outcome data that could be evaluated. There were small increases (7 to 12 liters per minute) in peak expiratory flow in the morning and the evening in both treatment groups, with no significant differences between the groups in the degree of change from base line (morning peak expiratory flow, P=0.49 at two months and P=0.82 at four months). Symptoms of asthma and use of 3-agonists decreased and the quality of life increased in both groups, with no significant differences between the groups. There were no significant changes in spirometric measurements or airway responsiveness. CONCLUSIONS: In children with mild or moderate asthma, the addition of chiropractic spinal manipulation to usual medical care provided no benefit.     

Aryl sulfonamides as selective PDE4 inhibitors

A series of novel selective phosphodiesterase 4 (PDE4) inhibitors has been developed which displays activity both in vitro and in vivo. These compounds possess good selectivity for the catalytic site of PDE4 over the high affinity Rolipram binding site. In vivo studies demonstrate a reduced propensity to display the emetic side effects which are commonly observed with PDE4 inhibitors.