Synthèse Facile de Pyrazines Disubstituées en 2 et 31)

Corynebacterium equi IFO 3730 was found to oxidize a wide variety of sec-alcohols, including alkanols, substituted alkanols, alkenols and cyclic alcohols, in moderate to high yields. Among them, the sec-alcohols which have longer carbon chains were oxidized more smoothly than those with smaller numbers of carbon. Although both enantiomers of unsymmetrically disubstituted carbinols were oxidized, the S form of 2-dodecanol was converted to the corresponding ketone a little faster than the other enantiomer.     

Effect of forskolin on collagen production in clonal osteoblastic MC3T3-E1 cells

The effect of forskolin on collagen production in osteoblasts was investigated by using clonal osteoblastic MC3T3-E1 cells cultured in a-minimum essential medium containing 0.1% bovine serum albumin. Forskolin increased the adenylate cyclase activity in membranes pelleted from homogenates of the cell line in a dose-dependent manner. The drug caused a 13-fold stimulation at 10(-4) M, indicating that the compound directly acts on adenylate cyclase, leading to an increase in the intracellular cAMP content of the cells. Collagen accumulation in the cultures was elevated by one-day treatment with 5 X 10(-5) M forskolin to about twice that in the controls. The stimulation was mainly due to an elevation in collagen synthesis but not to an inhibition of intracellular collagen degradation because forskolin dose-dependently increased collagen synthesis; it also significantly increased the amount of low-molecular-weight hydroxyproline found in the cultures. Cells treated with forskolin produced mainly type I collagen, as found in bone matrix in situ, with only small amounts of other types of collagen. Furthermore, forskolin time-dependently inhibited DNA synthesis in the cells, indicating that the increase in type I collagen synthesis by forskolin was not due to stimulated cell proliferation. These results suggest that cAMP is closely linked to the differentiation of osteoblasts in vitro.     

Postnatal development of the ovarian bursa of the golden hamster (Mesocricetus auratus): its complete closure and morphogenesis of lymphatic stomata

The golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. 1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. 2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. 3) Between 9 and 12 days of age U-shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. 4) Widening of the internal angle of the U-shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. 5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. 6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21-24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. 7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth-surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however. The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the damage.     

The different effects of recombinant human tumor necrosis factor on rat fibrosarcoma sublines

Summary The antitumor effect of recombinant human tumor necrosis factor (rH-TNF) on two clones of rat fibrosarcoma with different metastatic potential to lymph nodes was examined. The colony formation of clone A, which has high metastatic potential, was completely inhibited by continuous exposure to rH-TNF at 50 U/ml. In contrast, colony formation of clone G, which has low metastatic potential, was not inhibited by high concentrations of rH-TNF (10,000 U/ml). The inhibitory effect of rH-TNF on colony formation by clone A was also observed with a 1-h exposure to rH-TNF. This effect was time and concentration dependent, as determined by the colony assay, ³H-thymidine uptake assay, and ⁵¹Cr-release assay. ³H-thymidine and ³H-uridine uptake per cell of clone A exposed to rH-TNF was not decreased. This suggests that the mechanisms of the antitumor effect of rH-TNF were not due to inhibition of DNA and RNA synthesis of tumor cells. In vivo growth and lymph node metastases of clone A inoculated i.p. to Donryu strain rats were completely suppressed by 14 consecutive i.p. injections of 10⁵ or 10⁶ U/kg per day of rH-TNF. On the other hand the growth of clone G was not influenced by rH-TNF administration.     

Determination of age- and exercise-dependent changes in myoglobin contents in murine skeletal and cardiac muscles

A new method was developed to determine myoglobin (Mb) contents in as least as 5 mg of murine skeletal muscles. The method was a modification of Reynafarje's spectroscopic technique and was based on the Soret absorptions at 416 and 422 nm of the muscle extract. Mb contents in the skeletal and cardiac muscles increased with age and were widely different from muscle to muscle. The contents in most of the 13 muscles examined at the 30th week of age were less than 1.5 mg/g wet muscle, but the cardiac, soleus and gracilis muscles showed exceptionally high values of 2.2-6.0 mg/g. The relative content of one muscle to the other was the same independent of differences in age, strain and sex. There was a positive correlation between the muscle Mb contents and citrate synthase activity (r = 0.930). Young male mice (5 wk-old) were endurance-trained by a gradual load-increment program on treadmill for 10 weeks (5 days/week), but the training had no effects on the Mb contents. No substantial alteration of the contents was also observed in the limbs immobilized by plaster-fixation for 4 weeks.     

Ion Effects on the H+-Translocating Adenosine Triphosphatase and Pyrophosphatase Associated with the Tonoplast of Chora corallina

H⁺-translocating ATPase and pyrophosphatase (PPase) associatedwith the tonoplast of Chara corallina were isolated with theaid of a perfusion technique, and the effects of ions on theiractivities were studied. All the alkali metal cations testedstimulated the ATPase and ATPdependent H⁺ pumping activitiesonly by 10 to 40%. Anions, on the other hand, strongly affectedthe activities. Potassium salts of Cl^- and Br^- stimulated them,while F^- and NO₃^- inhibited them. By contrast, the H⁺-translocatingPPase was insensitive to anions but sensitive to cations. Theorder of cation stimulation was Rb⁺=K⁺>Cs⁺>Na⁺=Li⁺>choline⁺.NO₃^- (50 mil), thought to be a specific inhibitor of the tonoplast-typeH⁺-ATPase, inhibited the ATPdependent H⁺ pumping almost completelybut the ATPase activity by only about 50%. Na⁺ inhibited thePP₁-dependent H⁺ pumping (I_5O=5OmM) in the presence of 50 mMKCl but not the ATP-dependent one. The PPase was more sensitiveto F^- (I₅₀=400µM) than the ATPase. Both the H⁺-ATPaseand the H⁺-PPase required Mg²⁺ for their activities, althoughan excess was inhibitory to both. The different sensitivitiesof the PP₁-dependent and the ATP-dependent H⁺- pumping enzymesto ions correspond to the tonoplast enzymes of higher plantsand may be used as "markers" to distinguish between these enzymesin characean cells (Received October 2, 1987; Accepted May 18, 1988)     

Induction of interdigitating reticulum cell-like differentiation in human monocytic leukemia cells by conditioned medium from IL-2-stimulated helper T-cells

Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features. Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became intensely positive for HLA-DR antigen, cytoplasmic S-100β protein, and CD1 antigen. Functionally, the conditioned medium significantly down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned medium significantly down-regulated the expression of CD14 antigen. Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is necessary for the differentiation and maturation of IDC.     

Rhizome induction and plantlet regeneration of Cymbidium goeringii from flower bud cultures in vitro

Apical flower buds of Cymbidium goeringli Reichenbach fil. (ca 2 mm long) exeised from infloreseences (ca 5 cm long) were explanted on modified Murashige & Skoog medium (=MS medium) supplemented with N⁶-benzyladenine (BA) and -naphthaleneacetic acid (NAA). Within 107 days of culture, swelling growth, chlorophyll synthesis, and subsequent rhizome differentiation were observed. MS medium containing 0.1 mg l^-1 BA and 10 mg l^-1 NAA was found to be optimal for initiating rhizome development and subsequent plantlet regeneration.Explants cultured on MS medium supplemented with 1 mg l^-1 NAA alone formed a mass of rhizome branches. Multiple shoots of rhizome branches were induced from apical segments when rhizomes were transferred to MS medium containing 0.1 mg l^-1 BA and 10 mg l^-1 NAA.Abbreviations NAA -naphthaleneacetic acid - BA N⁶-benzyladenine     

Isolation and Identification of α-(γ-Aminobutyryl)-Hypusine

A new dipeptide, alpha-(gamma-aminobutyryl)-hypusine, was identified in bovine brain. This compound was isolated from trichloroacetic acid-soluble fraction of bovine brain with five steps of ion-exchange chromatography. Its structure was postulated by routine chemical analyses and determined by synthesis. The amount of the compound isolated from 1.2 kg of bovine brain was 870 nmol.     

An oxygen-evolving complex with a simple subunit structure - ‘a water-plastoquinone oxidoreductase” - from the thermophilic cyanobacterium Synechococcus sp.

An oxygen-evolving complex has been highly purified from the thermophilic cyanobacterium Synechococcus sp. The complex, which reproducibly showed 5 major polypeptide bands of 47, 40, 35, 30 and 9 kDa on SDS-polyacrylamide gel electrophoresis and contained 3.2 Mn per Q_A, had an oxygen-evolving activity of 300–400 μmol/mg chl per h in the presence of 5 mM MnCl₂; or CaCl₂. The complex most likely represents a minimum functional unit of the photosynthetic oxygen evolution.