Human fibroblast stromelysin catalytic domain: expression, purification, and characterization of a C-terminally truncated form.

Stromelysin-1 is a member of a tissue metalloproteinase family whose members are all capable of degrading extracellular matrix components. A truncated form of human fibroblast prostromelysin 1 lacking the C-terminal, hemopexin-like domain has been expressed in Escherichia coli and purified to homogeneity. Treatment of this short form of prostromelysin with (aminophenyl)mercuric acetate resulted in activation and loss of the propeptide in a manner identical with the wild-type, full-length protein. Kinetic comparisons using Nle11-substance P as a substrate showed that the wild-type stromelysin and the truncated form of the enzyme had similar kcat and Km values. Likewise, both enzymes displayed similar Ki values for a hydroxamate-containing peptide inhibitor. Taken together, these results indicate that the C-terminal portion of stromelysin is not required for proper folding of the catalytic domain, maintenance of the enzyme in a latent form, activation with an organomercurial, cleavage of a peptide substrate, or interaction with an inhibitor. Moreover, the active short form of stromelysin displayed a reduction in the C-terminal heterogeneity, a characteristic degradation of the full-length stromelysin, and thereby provides a more suitable protein for future structural studies.     

The role of inhibition processes in the development of functional properties of neurons of the vibrissa projection area in the cat somatosensory cortex

The paper deals with the contribution of intracortical inhibitory processes to the organization of receptive fields in the vibrissae projection area of the somatosensory cortex. Inhibition blockade by means of microelectrophoretic application of picrotoxin and bicucullin was shown to lead to a loss of directional sensitivity of neurones. Activation of inhibition at remote glutamate application led to opposite changes: the neurones became directionally sensitive, and dependence was found between the spatial localization of activated neurones and the character of changes of detector parameters. Inhibitory processes caused by natural afferent stimulation led to similar changes of functional characteristics of neurones.     

Rapid assessment of liposomal stability in blood by an aqueous nitroxide spin label

An electron spin resonance method using an aqueous nitroxide spin label, 2,2,6,-tetramethyl-piperidine-N-oxyl-4-trimethyl-ammonium, for rapid assessment of liposome stability in blood is presented. The retention of the nitroxide in liposomes is measured by its electron spin resonance signal intensity, a procedure which does not require separation of the sample from the blood. Any nitroxide that is released from the liposomes is reduced by external ascorbic acid which is added to the sample. The method permits kinetic studies on the integrity of liposomes in the presence of destabilizing factors such as detergent, blood, or alteration in temperature.     

Prostaglandin-sepharose: Application to the purification of bovine lung 15 (S) -hydroxyprostaglandin dehydrogenase

Prostaglandins E₁, F_1α and A₂ were covalently joined to the surface of Sepharose as carboxamide linkages. The insolubilized prostaglandins were shown to function effectively in the purification of 15(S) -hydroxyprostaglandin dehydrogenase.     

Ultrasound screening for clinically occult abdominal aortic aneurysm.

In a review of the records of 74 patients who had undergone repair of an abdominal aortic aneurysm at a community hospital between 1977 and 1983 we found that the aneurysm had been undiagnosed before rupture in 35%; these patients had an operative death rate of 50%, whereas elective repair carried a death rate of 4%. The characteristic patient was an obese man over the age of 55 years with hypertension, coronary artery disease, cerebrovascular disease or peripheral vascular disease. Ultrasound examination was performed in 45 patients with these characteristics, and six aneurysms were diagnosed. Either surgery or computed tomography confirmed the diagnosis. The rate of false-negative results was estimated by review of the charts of 100 men over the age of 55 years who had undergone abdominal ultrasonography for other indications: no undetected aneurysms were discovered over 3 years of follow-up. Routine screening in this high-risk group would improve the rate of diagnosis of this potentially fatal condition before rupture and offer the patient the lower mortality rate associated with elective surgery.     

1,3,6-Trihydroxy-7-methoxy-8-(3,7-dimethyl-2,6-octadienyl)xanthone from Garcinia cowa

1,3,6-Trihydroxy-7-methoxy-8-(3,7-dimethyl-2,6-octadienylxanthone has been isolated from the stems of Garcinia cowa.     

Sequential passage of alpha2mu-globulin through the hepatic endoplasmic reticulum and Golgi apparatus during secretion.

Studies on the synthesis and secretion of the sex-dependent urinary protein, alpha2mu-globulin, have been extended by establishing its sequential passage from the rough to the smooth endoplasmic reticulum and Golgi-rich fractions of the liver of adult male rats. After injection of 14C-labeled amino acids, the maximum radioactivity of alpha2mu occurred at 20 min in the rough, 25 min in the smooth microsomes and 30 or 35 min in the Golgi-rich fractions. Radioactive alpha2mu-globulin appeared in the bloodstream and kidneys after a lag of 20--25 min. Results indicate that alpha2mu-globulin follows a secretory pathway similar to that of serum albumin.