Apoprotein formation and heme reconstitution of cytochrome P-450cam

Apoprotein suitable for heme reconstitution has been prepared by an acid/butanone extraction of cytochrome P-450cam at pH 2.5. Absorption spectra of apo-P-450cam indicate less than 2% residual holoenzyme. Four tryptophan residues per molecule were estimated from the aromatic absorbance region of denatured apoprotein. Heme-reconstituted holoprotein was purified in 30% yield to a specific activity equivalent to the native enzyme. Absorption and EPR spectra of 57Fe- and 54Fe-heme-enriched P-450cam reveal complete restoration of the native active site.

Characteristics of the beta 1-and beta 2-adrenergic-sensitive adenylate cyclases in glial cell primary cultures and their comparison with beta 2-adrenergic-sensitive adenylate cyclase of meningeal cells

The agonist specificity pattern of the beta-adrenergic adenylate cyclase in glial primary cultures was not typical of either beta 1- or beta 2-adrenergic receptors. The dose-response curves for adrenaline did not correspond to simple mass action kinetics and their computer analysis suggests the presence of both beta 1- and beta 2-adrenergic-sensitive adenylate cyclase (58 plus or minus 17% and 42 plus or minus 17% respectively). Similar properties of beta 1- and beta 2-adrenergic-sensitive adenylate cyclases were found by computer analysis of the dose-response curves for isoprenaline in the presence of a constant concentration of practolol (a selective beta 1 antagonist) (55 plus or minus 10% and 45 plus or minus 10% of beta 1- and beta 2-sensitive adenylate cyclase respectively). The curves for displacement of [3H]dihydroalprenolol by practolol confirm these results. For purpose of comparison, the beta-adrenergic receptors of meningeal cells in cultures were subjected to similar analysis. The results clearly showed that these cells exclusively contained beta 2-adrenergic receptors.

Neuronal, glial and meningeal localizations of neurotransmitter-sensitive adenylate cyclases in cerebral cortex of mice

The neurotransmitter-sensitive adenylate cyclases, respectively present in the dissociated cells of new-born mouse cerebral cortex (containing both neuronal and glial cells) and in a homogeneous population of glial cells, were compared. The dissociated cells from the cerebral cortex of new-born mice were found to contain Ca2+-, dopamine-, serotonin- and purinergic-sensitive adenylate cyclases. The dopaminergic receptor involved was extensively characterized and was similar to that described in adult animals. Beta-adrenergic-sensitive adenylate cyclase was present but was poorly active. After 3 weeks in culture, the neurons disappeared and a homogeneous population of glial cells was obtained (96% of the cells synthetized glial fibrillary acidic protein). These glial cells contained a highly potent beta-adrenergic-sensitive adenylate cyclase, and adenosine- adn Ca2+-sensitive enzymes. Ca2+ stimulation of the adenylate cyclase was due to the presence of calmodulin. We suggested that the dopaminergic- and serotoninergic-sensitive adenylate cyclases which disappeared during culture are probably localized in neuronal cells. The presence of Ca2+-, adenosine- and beta-adrenergic-sensitive adenylate cyclases in glial cells does not exclude their presence in neuronal cells. For comparison, the same experiments were conducted on meningeal layers of new-born mice and on meningeal cells in culture. They both contained beta-adrenergic- and purinergic-sensitive adenylate cyclases.

Alpha 1 and alpha 2 Adrenergic receptors in mouse brain astrocytes from primary cultures

Mouse brain astrocytes from primary cultures were found to contain both alpha 1 and alpha 2 adrenergic receptors. 3H WB 4101 labeled one category of binding site (KD = 1.5 +/- 0.39 nM, Bmax = 64 +/- 7.9 fmoles/mg protein) with typical alpha 1 adrenergic specificity (WB 4101 greater than prazosin greater than yohimbine). The density of alpha 1 adrenergic receptors was 2-3 times higher in mouse cerebral cortex than in glial cells. Like rat brain [U'Pritchard et al, 1979; Rouot et al, 1980], mouse glial cells were found to contain two categories of 3H clonidine binding sites: high affinity sites, which were identical to the high but not to the low affinity sites found in rat brain, since 1) they displayed the same affinity for 3H clonidine (KD = 1.2 +/- 0.13 nM, n = 4) and the same typical alpha 2 adrenergic specificity (yohimbine greater than WB 4101 greater than prazosin); 2) the dissociation rate constant for clonidine binding was equal to 0.06 min-1, a value close to that found previously for the high affinity 3H clonidine binding sites in rat brain (0.05 min-1); and 3) divalent cations augmented and guanyl nucleotides reduced 3H clonidine binding as in rat brain. Na+ decreased 3H clonidine binding in a complex manner. The number of high affinity sites in glial cells (52 +/- 9.4 fmoles/mg protein, n = 4) was half the number found in mouse cerebral cortex (98 fmoles/mg protein). Low affinity 3H clonidine binding sites (KD = 81 +/- 18 nM, Bmax = 96 +/- 5.8 fmoles/mg protein, n = 3) were not fully characterized. In conclusion, glial cells contained the same alpha adrenergic receptors as those described in brain, but their physiological function is not yet known.

Expression of foreign H-2-like antigens by a chemically-induced murine tumour (MCG4)

Alien H-2k-like antigens were found to be expressed by a methylcholanthrene induced tumour of BALB/c (H-2d) origin. H-2 specificities of the k haplotype were detected on this tumour by a variety of serological techniques, including 51Cr-release cytotoxicity, microradioassay and absorption. The antisera employed were conventional polyspecific alloantisera, typing sera with restricted specificty and monoclonal hybridoma-derived anti-H-2k antibodies. The tumour has a low expression of the private specificty 31, which characterizes Kd molecules, and does not seem to express the private specificities of Dd, Kk and Dk molecules. It appears to express predominantly alien H-2-like antigens which are very similar to but not identical with normal H-2k molecules.

The diagnostic and therapeutic role of angiography in lingual arterial bleeding

Selective external carotid angiography proved effective in the diagnosis of lingual arterial bleeding in seven patients. The cause of the hemorrhage was carcinoma of the tongue in six patients and stab wounds in one. Therapeutic Gelfoam embolization controlled hemorrhaging in four patients.

A syngeneic anti tumor serum recognizing a complex H-2 alloantigen

A methylcholanthrene induced tumor of BALBc (H-2d) origin had a high rate of spontaneous regression when transplanted into syngeneic animals. The tumor induced in BALB/c mice iso-antibodies with high anti-tumor cytotoxic activity. A specificity analysis of such BALB/c anti MCG4 sera revealed that the antibodies were directed against a tumor antigen which is very similar to H-2- alloantigens (e.g. H-2.5) expressed on normal cells of certain foreign mouse strains. The sera also reacted with nine out of ten B10.W congenic strains bearing H-2wi haplotypes derived from wild mice. Whether the tumor antigen is identical with foreign H-2 antigens or only cross-reactive cannot be decided at present.

Absence of four H-2d antigenic specificites in an H-2d sarcoma

MCG4 is a BALB/c sarcoma induced as a solid tumour with 0.2 mgs of methylcholantrene. The primary tumour was serially transplanted subcutaneously in syngeneic mice. The ascites form obtained was sued to study the expression of H-2 antigeneic specificities in a postlabelling radioassay. MCG4 did not express H-2D.4 (private specificity of H-2d haplotypes) as well as H-2.3, H-2.8 and H-2.13 (public specificities). In addition it expressed H-2.5 (a public specificity not present in H-2d cells). These results were confirmed by quantitative absorption analysis using MCG4 and positive-negative normal lymphoid cells for a particular specificity. Results are discussed with regard to the control of expression of H-2 antigens by regulatory genes.

Edema in Spawning Salmon

Salmon develop edema during their spawning migration from the sea to fresh water. As measured by the wick technique, fluid pressure in both subcutaneous and peritoneal compartments rises from negative values at sea to positive values in rivers. Concomitantly, blood colloid osmotic pressure falls during the spawning migration. Some of the degenerative changes leading to the death of postspawning salmon probably result from the total-body edema herein described.

Molecular Buoyancy and Osmotic Equilibrium

Measurements of osmotic equilibrium of colloidal solutions, ranging from 170,000 to 20,000 in molecular weight, show that the negative buoyancy of the solute molecules is additive to the osmotic pressure. Seen together with earlier measurements of positive buoyancy of oil suspensions, these data confirm that the osmotic interaction between solute and solvent at equilibrium is purely a force-coupling at the free surface.

Effect of gravity on osmotic equilibria

Experiments with colloidal suspensions of oil and iron oxide at equilibrium show that the buoyancy of the suspended particles is additive to the osmotic pressure and that the relation remains with the free surface and not with the membrane. The experiments contribute to the general concept that osmotic pressure is caused by the dispersal pressure of solute molecules and that the osmotic interaction with the water at equilibrium is due solely to a coupling at the free surface.