The actions of 5-hydroxytryptamine3 (5-HT3) receptor agonists and antagonists have been determined on the recombinant murine 5-HT3 R-A and an apparent splice variant of this subunit, termed 5-HT3 R-AS. When expressed in Xenopus laevis oocytes, both forms of the subunit functioned as a homo-oligomeric complex and exhibited inward current responses to bath applied 5-HT. Analysis of the 5-HT concentration-response curve obtained with either homo-oligomer gave Hill coefficients greater than two, suggesting positive co-operativity within the receptor complex. The rank order of potency of a range of 5-HT3 receptor agonists [m-chlorophenylbiguanide > 5-HT > 2-methyl-5-HT (2-Me-5-HT) > or = phenylbiguanide] was identical for both subunits. Indeed, with the exception of 2-Me-5-HT, for the agonists tested there was little difference across the subunits in either their potency, or the maximal current response that they elicited relative to 5-HT. Although 2-Me-5-HT exhibited a similar potency for both subunits, the maximal response evoked by this agonist at the 5-HT3 R-AS subunit was much reduced when compared to the 5-HT3 R-A subunit. The 5-HT-induced current mediated by either form of the subunit was inhibited by the 5-HT3 receptor selective antagonists BRL 46470, granisetron and ondansetron and the non-selective antagonists (+)-tubocurarine, metoclopramide and cocaine in a reversible and concentration-dependent manner. These antagonists did not discriminate between the subunits and their potencies were similar to those reported previously for 5-HT3 receptors native to murine neuronal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Two-dimensional echocardiographic and color flow Doppler detection of an unusual pulmonary venous anomaly: anomalous right pulmonary venous return to the right atrium by way of three separate orifices.

In this report, we describe the echocardiographic findings of a patient with anomalous right pulmonary venous return to the right atrium by way of three separate pulmonary vein orifices. The color flow Doppler examination was essential for identification of the pulmonary veins and their connection to the right atrium.

Cardiac Catheterization↗

PubMedDate not supplied

Synthesis, characterization, and relaxivity of two linear Gd(DTPA)-polymer conjugates.

Two linear polyamide conjugates of Gd(DTPA)2- were synthesized and characterized by high-resolution nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC). DTPA was copolymerized with two different diamines, 1,6-hexanediamine and trans-1,4-cyclohexanediamine, yielding the polymers DTPA-HMD and DTPA-CHD, with low polydispersity. Their molecular flexibility in solution was studied using 13C spin-lattice relaxation time measurements, indicating that the cyclohexanediamine linking moiety of the DTPA-HMD polymer is more rigid than that of DTPA-CHD. The influence of the flexibility of the linking functionalities on the relaxivity of the Gd3+-DTPA-polymer conjugates was studied by water nuclear magnetic relaxation dispersion (NMRD). The relaxivity of the Gd(DTPA-CHD) polymer was only slightly higher than that of the Gd(DTPA-HMD) polymer, and only two times higher than the usual values for small Gd-DTPA-like chelates. The low relaxivities obtained for both polymers, much lower than expected from the polymer apparent molecular weights, result from their substantial residual flexibility, and also from a too long, nonoptimal, value of the inner-sphere water exchange rate. These polymeric compounds are also cleared very quickly from the blood of rats, indicating that they are of limited value as blood pool contrast agents for MRA.

Animals↗

PubMedDate not supplied

Southwestern Athabaskan genetic diseases.

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Canada↗

PubMedDate not supplied

Relationship of cytomorphology to spirometric findings in cigarette smokers.

The objective of the study was to determine the relationship between sputum cytomorphology and pulmonary function. A cross-sectional correlation analysis of results from pulmonary function testing and eight cytomorphologic indices of inflammation and metaplasia was conducted in 143 smokers registered in a residential smoking-cessation program. Stepwise multiple regression analysis revealed that after adjusting for age and smoking history, lower levels of pulmonary function were related significantly to higher levels of macrophage pigmentation, neutrophils and metaplasia. Higher levels of macrophages were associated with higher levels of pulmonary function. The overall regression coefficient, 0.35, was highly significant (F[5,136] = 14.84, P = .0001). Categorical analyses revealed that smokers with high counts of neutrophils, macrophage pigmentation, columnar cells, spirals and metaplasia were two to three times more likely to have abnormal pulmonary function than were those with low counts. From these results we conclude that elevations in certain cytologic indices are associated with abnormal lung function. These findings may reflect the pathophysiology of obstructive lung disease. Longitudinal studies are required to determine whether cytomorphologic parameters can identify individuals at risk for functional deterioration at a stage amenable to intervention.

Adult↗

PubMedDate not supplied

For the benefit of all.

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Adult↗