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[Kinetic study of the lumbar vertebrae and the lumbosacral passage in German shepherd dogs. 1. Functional anatomy and kinetic foundation].

In the dog congenital or acquired stenosis of the lumbosacral region is commonly encountered. In humans the lumbosacral junction is the most often affected part of the vertebral column. Lumbosacral instability, one possible etiology for stenosis of the vertebral canal plays an important role in man. This study summarizes the functional anatomy and some important geometric and kinematic considerations necessary for the understanding of the motion (flexion-extension) between two adjacent vertebra.

Animals↗

Kinetics and mechanism of degradation of some 2-sulfanilamidopyrimidine derivatives. Part III. The use of Hammett equation for kinetic investigation of 2-sulfanilamidopyrimidine derivatives autoxidation.

General first-order rate constants for autoxidation of sulfadiazine, sulfamerazine, sulfadimidine, sulfaperine and sulfamethoxydiazine in the air oxygen atmosphere, in solutions of pH 4-7, at 403, 411 and 418 K were determined from the absorbance measurements in 0-1 mole/dm3 HCl at 243 or 333 nm, using the so-called "subtraction technique". The thermodynamic parameters of this reaction were determined (deltaHa, deltaH not equal to, deltaS not equal to, deltaG not equal to and logA). The effect of the substituents in positions 4, 5 and 6 of the pyrimidine ring on the rate of autoxidation was interpreted in terms of the Hammett equation.

Drug Stability↗

Kinetics and mechanism of degradation of some 2-sulfanilamidopyrimidine derivatives: part IV. Mechanism and kinetics of specific acid-catalyzed hydrolysis of sulfadimidine.

The following products of acid hydrolysis of sulfadimidine (SDMP) were isolated and identified: sulfanilic acid (Sac), sulfanilamide (SA), 2-amino-4, 6-dimethylprimidine (ADMP) and 2-hydroxy-4, 6-dimethylpyrimidine (HDMP). The apparent first-order rate constants (k1, k2 and k3) were determined for the reaction: (formula: see text). The catalytic rate constants kH+ = ki/[H+] and the thermodynamic parameters delta Ha, delta H not equal to, deltaS not equal to, deltaG not equal to and log A were also determined for that reaction.

Chemical Phenomena↗

Cytofluorometric analysis of the kinetics of lymphocyte transformation after phytohemagglutinin stimulation: comparison with the kinetics of thymidine incorporation.

The technique of flow cytofluorometry has been employed to assess the response of unfractionated and highly purified human lymphocyte subpopulations to phytohemagglutinin (PHA) and pokeweed mitogen. Normal values for cytofluorometric responses were established and compared to the uptake of tritiated thymidine in simultaneous experiments. Cytofluorometric analysis offered the advantages of increased sensitivity and direct measurement of DNA content per cell, and provided percentages and absolute numbers of responding cells. B-cell responses to pokeweed mitogen were absent, but brisk T-cell responses were noted. Between 4% and 8% of highly purified human B cells were found to respond to PHA by increasing their DNA content; modest but significant uptake of tritiated thymidine by B cells following PHA stimulation was also observed.

B-Lymphocytes↗