Human hypoxanthine-guanine phosphoribosyltransferase

A mutant form of human hypoxanthine-guanine phosphoribosyltransferase (HPRTToronto) was isolated from erythrocytes of a male patient with gout due to a partial deficiency of enzyme activity. The tryptic peptides of HPRTToronto were mapped by reverse-phase high pressure liquid chromatography in an attempt to define the precise abnormality in its primary structure. Sequence analysis of the single aberrant peptide in HPRTToronto revealed an arginine to glycine amino acid substitution at position 50. A single nucleotide change in the codon for arginine 50 (CGA leads to GGA) could explain this substitution.     

Effect of prostaglandins on lipid transfer between high- and low-density lipoproteins in human plasma

Prostaglandin (PG) E1 was shown to stimulate the transfer of phosphatidylcholine and cholesterol esters from human high density lipoproteins to low density lipoproteins. The enhancement of the interlipoprotein lipid transfer by PGE1 was observed both at low prostaglandin concentrations under conditions of spontaneous exchange as well as in the presence of the lipoprotein-depleted plasma and the partly purified lipid transfer plasma protein. At the same time PGE2 showed no significant influence on the interlipoprotein lipid transfer. It is supposed that the effect of PGE1 is due to the PGE1-induced reorganization of the high density lipoprotein surface and that the PG-lipoprotein interaction is a factor which regulates cholesterol homeostasis.     

Morphological characteristics of the motor neurons of the spinal cord in physical loading up to the limit

The experiments have been performed on 98 white rats adapted and nonadapted to the effect of physical loadings. The loadings up to the limit are reached by swimming of the rats up to fatigue. The swimming lasts for 10-15, 20-35, 40-65, 70-90 h. Under the conditions mentioned, morphological changes of the neurons are of mosaic pattern. Light optic and electron microscopic methods demonstrate swelling of neurons, endocellular and pericellular edema, vacuolization, appearance of gigantic degeneratively altered mitochondria, presence of vesicles in mitochondria, hollow mitochondria, dilated cysterns of the endoplasmic reticulum, degenerated synapses and glial reaction. These changes are considered as adaptive and compensatory reactions in the process of physiological strain of the organism, directed towards increasing stability against the effect of the extermal factor. In the animals nonadapted to any physical loadings, morphological changes in neurons of the ventral horns of the spinal cord are more deeply and widely spread in character.     

The functional anatomy of the lower limb of the howler monkey (Alouatta caraya)

The howler monkey possesses unique anatomical adaptations associated with its arboreal habit. The behavioral elements are described by locomotor pattern, substrate, timing and rhythm of movement. The most significant motor adaptations are correlated clearly and directly with musculoskeletal features of the lower limb. The orientation of the joints within the limb, the shape of the joint surfaces, their bony environments, and the important planes of muscular control are the foundations for the observable locomotor behaviors.     

Altered patterns of protein phosphorylation in articular chondrocytes treated with interleukin-1 or synovial cytokines

Cultures of lapine articular chondrocytes were exposed to purified, human, recombinant interleukin-1 alpha or partially purified preparations of lapine, synovial, cytokines in the presence of [32P]orthophosphate. After 30 min incubation, phosphoproteins were extracted from the cells, separated by two-dimensional gel electrophoresis and visualized autoradiographically. Analysis of the autoradiograms revealed that interleukin-1 and the synovial factors produced marked changes in the pattern of protein phosphorylation. The synovial cytokines induced many of the same changes as interleukin-1, as well as a number of unique changes. This finding is consistent with the notion that, in addition to interleukin-1, synoviocytes secrete other cytokines which modulate the metabolism of chondrocytes. These data support the idea that signal transduction in chondrocytes responding to interleukin-1 involves the activation of one or more protein kinases.