The stimulatory effect of beta-endorphin on the plasma prolactin levels was diminished in the rats treated with 6-hydroxydopamine

Intraventicular injection of beta-endorphin (beta LPH_61^?91) in urethane anesthetized male rats led to a dose dependent increase of plasma prolactin levels. Intravenous injection of apomorphine completely abolished the stimulatory effect of beta-endorphin. Animals treated with 6-hydroxydopamine (6-OHDA) and 6-OHDA plus desmethylimipramine showed inhibition of beta-endorphin induced prolactin release. These results suggest that beta-endorphin presynaptically inhibits the activity of dopaminergic neurones, leading to the stimulation of plasma prolactin levels.     

Synthesis and in vitro anti Mycobacterium tuberculosis activity of a series of phthalimide derivatives

New phthalimide derivatives were easily prepared through condensation of phthalic anhydride and selected amines with variable yields (70–90%). All compounds (3a–l) were evaluated against Mycobacterium tuberculosis H₃₇Rv using Alamar Blue susceptibility. The compounds 3c, 3i, and 3l have the minimum inhibitory concentrations (MICs) of 3.9, 7.8, and 5.0 μg/mL, respectively, and could be considered new lead compounds in the treatment of tuberculosis and multi-drug resistant tuberculosis.     

Structural characterization and dynamics of globotetraosylceramide in vascular endothelial cells under TNF-α stimulation

In several vascular inflammatory reactions (i.e. immunity and thrombosis) inflammatory mediators lead to the activation of vascular endothelial cells (EC). To date, a number of functional molecules induced on the surface of activated-EC have been identified. We report here that Globotetraosylceramide (Gb4), a glycosphingolipid expressed in EC, is a novel inducible molecule on EC activated by TNF-α. The cell surface expression of Gb4 is increased in a time-dependent manner under TNF-α stimulation, which shows distinct expression kinetics of major proteins induced by TNF-α on EC. MALDI-TOF-MS analysis revealed that the enhanced Gb4 predominantly contains C24:0 fatty acid in the ceramide moiety. Isolated caveolae/lipid raft-enriched detergent insoluble membrane domains in activated-EC predominantly contain this molecular species of Gb4. Gb4 containing C16:0 fatty acid in the ceramide moiety, which is known to constitute the major species of Gb4 in plasma, is also found as a major molecular species in EC. These observations indicate that Gb4, especially with very long fatty acid, is enhanced in EC during its inflammatory reaction, and suggest the potential utility of Gb4 as a biomarker for monitoring inflammation status of EC involving its related diseases.     

Mutagenicity,sister chromatid exchange inducibility andin vitro cell transforming ability of particulates from Athens air

Airborne particulates were collected over a period of twelve months by the use of Hi-Vol samplers in the basin of Athens, Greece. N-Hexane extracts were tested in a battery ofin vitro tests for their ability to induce mutation in bacteria as well as mutation, sister chromatid exchange and morphological transformation in cultured mammalian cells. Positive results were found for mutagenicity withSalmonella strain TA98 in the Ames assay, for sister chromatid exchange induction in CHO cells and for transformation in BALB/c 3T3 cells in culture. They also showed weak non-doserelated induction of ouabain resistance in BALB/c 3T3 cells. The contribution of oxidizing and nitrating agents found in the Athens atmosphere, together with sunlight UV irradiation in the formation of direct acting mutagens and potential carcinogens from ambient polycyclic aromatic hydrocarbons, is suggested.Abbreviations FCS fetal calf serum - FPG fluorescent-plus-Giemsa technique - oua^R ouabain resistant - PAH polycyclic aromatic hydrocarbon - SCE sister chromatid exchange - TSP total suspended particulate     

Interleukin-6 triggers the association of its receptor with a possible signal transducer, gp130

Interleukin-6 mediates pleiotropic functions in various types of cells through its specific receptor (IL-6-R), the cDNA of which has already been cloned. We report here that an 80 kd single polypeptide chain (IL-6-R) is involved in IL-6 binding and that IL-6 triggers the association of this receptor with a non-ligand-binding membrane glycoprotein, gp130. The association takes place at 37 degrees C within 5 min and is stable for at least 40 min in the presence of IL-6, but does not occur at 0 degree C. Human IL-6-R can associate with a murine gp130 homolog and is functional in murine cells. Mutant IL-6-R lacking the intracytoplasmic portion is functional, suggesting that the two polypeptide chains interact to involve their extracellular portion. In fact, a soluble IL-6-R lacking the transmembrane and intracytoplasmic domains can associate with gp130 in the presence of IL-6 and mediate its function. These findings indicate that the complex of IL-6 and IL-6-R can interact with a non-ligand-binding membrane glycoprotein, gp130, extracellularly and can provide the IL-6 signal.     

Effect of lard and corn oil intake on serum lipids in young men

An experimental diet with lard (30 g/day for 7 days) and corn oil (30 g/day for 7 days) on high carbohydrate (basal diet) was given to four healthy Japanese young men and the effect of diets containing different fat on serum lipids was examined. Serum total cholesterol was increased significantly from a basal diet of 106 +/- 23 to 141 +/- 26 mg/dl on lard diet, and then decreased significantly (p less than 0.05) to 111 +/- 22 mg/dl on corn oil diet. Serum triglycerides increased significantly (p less than 0.01) from 66 +/- 38 to 173 +/- 32 mg/dl on basal diet. Serum HDL-cholesterol was decreased significantly (p less than 0.01) from 41.9 +/- 1.6 to 31.2 +/- 3.8 mg/dl on lard diet and increased significantly (p less than 0.05) to 41.9 +/- 4.6 mg/dl on corn oil diet. Serum HDL-cholesterol fraction was decreased significantly (p less than 0.01) from 41.6 +/- 4.9 to 28.1 +/- 3.2% on basal diets, but increased significantly (p less than 0.05) to 44.3 +/- 3.1% on lard diet, and then decreased to 36.3 +/- 2.5% on corn oil diet. Serum HDL phospholipid fraction decreased significantly (p less than 0.05) from 62.5 +/- 6.7 to 50.7 +/- 1.8% on basal diet and increased significantly (p less than 0.05) to 60.4 +/- 1.0% on lard and corn oil diet. Serum phospholipids did not change by experimental diets. It is concluded that lard and corn oil have different and specific roles in lipid metabolism.     

In vivo biotinylation of fusion proteins expressed in Escherichia coli with a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit.

Biotinylation of fusion proteins in E. coli was studied using a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit. As the biotinylation sequence, we examined two sequences: one was of amino acid residues [84-123] of 1.3S, a partial sequence containing a region from a conserved tetrapeptide (Ala-Met-Bct-Met) around the biotinyl lysine (Bct) to the carboxyl terminal; the other was of an almost entire sequence [18-123]. We constructed recombinant plasmids for fusion proteins of beta-galactosidase, of chloramphenicol acetyltransferase, and of alkaline phosphatase. We found the biotinylation in the [18-123] sequence fused to alkaline phosphatase.     

Determination of insulin-like growth factor-I in normal subjects and in patients with growth hormone disorders by radioimmunoassay using biosynthetic homologous peptide

A highly sensitive and specific RIA for IGF-I has been developed using recombinant DNA-derived IGF-I of very high purity and specific antiserum to it. This assay system could detect IGF-I at as low concentrations as 20-30 ng/ml. The intra-assay and interassay coefficients of variation at various concentrations of IGF-I were 4.9 to 6.5% and 5.4 to 8.0%, respectively. The recovery rate of pure IGF-I added to plasma was 77.0 +/- 3.7%. The antiserum did not cross-react with porcine insulin, biosynthetic human insulin, hGH, hEGF, the synthetic C-domain of IGF-I or that of IGF-II, but reacted equally with an analog, Thr59-IGF-I. Plasma IGF-I was extracted by the acid-ethanol method before assay to separate IGF-I from its binding protein. When plasma IGF-I was assayed without extraction, the inhibition curves of serial dilution of plasma samples from several individuals were not parallel to the standard curve of IGF-I. The plasma concentration of IGF-I was 147 +/- 49 ng/ml (mean +/- SD) in 156 normal adults aged from 20-59 years. As reported by others, the IGF-I levels were low in cord plasma (41.8 +/- 23.5 ng/ml) and plasma of patients with GH deficiency (64.6 +/- 42.0 ng/ml), while its levels were high in normal children of pubertal ages (12-13 yr, 365 +/- 126 ng/ml) and in patients with active acromegaly (562 +/- 115 ng/ml). This RIA system is a simple and useful method for determining plasma IGF-I in normal and diseased states.     

Scanning electron-microscopic studies on the three-dimensional structure of sarcoplasmic reticulum in the mammalian red,white and intermediate muscle fibers

Summary The three-dimensional structure of the sarcoplasmic reticulum (SR) in the red, white and intermediate striated muscle fibers of the extensor digitorum longus muscle of the rat was examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure.In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of the A-I junction. Numerous slender sarcotubules, originating from the A-band side terminal cisternae, extend obliquely or longitudinally and form oval or irregular shaped networks of various sizes in front of the A-band, then become continuous with the tiny mesh (fenestrated collar) in front of the H-band. The A-and H-band SR appears as a single sheet of anastomotic tubules. Numerous sarcotubules, originating from the I-band side terminal cisternae, extend in threedimensional directions and form a multilayered network over the I-band and Z-line regions. At the I-band level, paired transversely oriented mitochondria partly embrace the myofibril. The I-band SR network is poorly developed in the narrow space between the paired mitochondria, but is well developed in places devoid of these mitochondria.The three-dimensional structure of the SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a much smaller total volume of SR than the mitochondria-poor white fiber. Moreover, the volume of SR of the intermediate fiber is intermediate between the two.