锌和铜在生长抑素对链佐霉素引起的胰岛B细胞损伤的保护中的作用

我们以前的工作指出,生长抑素可以预防链佐霉素对大鼠胰岛B细胞的损伤。本工作测定给药前后大鼠血清和组织中Zn、Cu含量,以进一步观察链佐霉素破坏大鼠胰岛B细胞后生长抑素预防效应的可能机制。结果为:链佐霉素(STZ)(35mg/kg,ip)注射后24h的大鼠,血清Zn浓度下降,Cu浓度升高,Zn/Cu比值倒置;用生长抑素作预防性注射后,血清Zn浓度与正常对照水平相同,Cu浓度虽稍有升高,但Zn/Cu比值正常。保护组的血清Zn与损伤组比较,差异极为显著。两组的Zn/Cu比值同样也具有显著差异。在给药后72h,血清Zn/Cu比值在各组之间仍呈上述关系,但差异减小。在大鼠胰腺,注射链佐霉素后胰腺组织Zn浓度未见改变,但生长抑素作预防性注射可使组织锌含量增加。上述结果提示,在生长抑素对胰岛B细胞的保护机制中可能有Zn和Cu的参与。预防性注射生长抑素所引起的高Zn状态可能有利于机体细胞含Zn酶类的活性,增强已损伤细胞的修复。     

C-banding patterns in the AustralianBulbine (Liliaceae): The annual group,B. semibarbata s. lato

Chromosome C-band patterns have been studied in 34 populations of the Australian annualBulbine group, which comprises 4x (2n = 26, 28), 8x (2n = 52, 54) and 12x (2n = 78) populations. The 2n = 26B. semibarbata populations have a simple, low heterochromatin pattern with very minor polytypic variation. The 2n = 28 populations, corresponding morphologically to a group given separate status asB. alata, are similar in pattern but exhibit pronounced enhancement of telomeric and, more particularly, centromeric dot bands. NOR heterochromatin and satellites are difficult to identify inB. alata but appear to occur in different positions from the 26-chromosome karyotype. Eastern Australian 8 x patterns are consistent with a proposed hybrid ancestry,B. semibarbata ×B. alata. Annual and perennial C-band profiles in the AustralianBulbine are discussed briefly in relation to the additive and transformation models of heterochromatin evolution and to the possible adaptive significance of variation in heterochromatin content.Cytoevolution in the AustralianBulbine 2; for part 1 see Pl. Syst. Evol.157, 201–217.     

Monoamine Oxidase-Inhibiting Properties of SR 95191, a New Pyridazine Derivative, in the Rat: Evidence for Selective and Reversible Inhibition of Monoamine Oxidase Type A In Vivo but Not In Vitro

In rodents, SR 95191 [3-(2-morpholinoethylamino)-4-cyano-6-phenylpyridazine] has been shown to be active in animal models of depression. The profile of activity of SR 95191 suggests that the compound is a selective and short-acting type A monoamine oxidase (MAO) inhibitor (MAOI) in vivo. In the present study, the interaction of SR 95191 with MAO-A and MAO-B activity was further examined in vivo and in vitro. In brain, liver, and duodenum of pretreated rats, SR 95191 selectively inhibited MAO-A (ED50 = 3-5 mg/kg, p.o.), whereas MAO-B was only weakly inhibited for doses as high as 300 mg/kg, p.o. In vivo, SR 95191 (1-100 mg/kg, p.o.) antagonized, in a dose-dependent fashion, the irreversible inhibition of brain and liver MAO-A induced by phenelzine. Finally, dopamine and 5-hydroxytryptamine depleted from their striatal stores by tetrabenazine were able to displace SR 95191 from the active site of MAO-A. However, ex vivo, kinetic studies showed that the inhibitory effect of SR 95191 (1-10 mg/kg) towards MAO-A was noncompetitive and was unchanged after dilution or dialysis. In vitro, the inhibition of brain MAO-A, but not MAO-B, by SR 95191 was time dependent, with a 19-fold decrease in the IC50 values being observed over a 30-min incubation period (140 to 7.5 microM). At this time, the SR 95191-induced inhibition of MAO-A was not removed by repeated washings. When the reaction was started by adding the homogenate without prior preincubation with SR 95191, the inhibition of brain MAO-A was fully competitive (Ki = 68 microM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition by Cyclic AMP of Phorbol Ester-Potentiated Norepinephrine Release from Guinea Pig Brain Cortical Synaptosomes

The involvement of Ca2+/phospholipid-dependent protein kinase (protein kinase C, PKC) and cyclic AMP-dependent protein kinase in the K+-evoked release of norepinephrine (NE) was studied using guinea pig brain cortical synaptosomes preloaded with [3H]NE. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a potent activator of PKC, enhanced the K+-evoked release of [3H]NE, in a concentration-dependent manner, but with no effect on the spontaneous outflow and uptake of [3H]NE in the synaptosomes. The apparent affinity of the evoked release for added calcium but not the maximally evoked release was increased by TPA (10(-7) M). Inhibitors of PKC, polymyxin B, and a more potent inhibitor, staurosporine, counteracted the TPA-induced potentiation of the evoked release. Both forskolin and dibutyryl cyclic AMP (DBcAMP) enhanced the evoked release, but reduced the TPA-potentiated NE release. A novel inhibitor of cyclic AMP-dependent protein kinase, KT5720, blocked both the forskolin-induced increase in the evoked release and its inhibition of TPA-induced potentiation in the evoked release, thereby suggesting that forskolin or DBcAMP counteracts the Ca2+-dependent release of NE by activating cyclic AMP-dependent protein kinase. These results suggest that the activation of PKC potentiates the evoked release of NE and that the activation of cyclic AMP-dependent protein kinase acts negatively on the PKC-activated exocytotic neurotransmitter release process in brain synaptosomes of the guinea pig.     

The profile distribution of total and extractable boron in cacao-growing soils in southwestern Nigeria

The profile distribution of total and extractable B was determined in 16 Nigerian cacao-growing soil profiles formed from different parent materials. Total B for all soils ranged from 8 to 54μgg⁻¹ with a mean of 24μgg⁻¹. The soils formed from sandstones in the rainforest zone contained higher amounts of total B than soils derived from basement complex. Boron extractable in hot water, in 0.1% CaCl₂, and in 1N NH₄OAc varied from 0.13 to 1.38, 0.44 to 1.20 0.03 to 0.56μgg⁻¹ respectively. The corresponding means were 0.66, 0.75 and 0.27μgg⁻¹ B. Soils on metamorphic rocks gave the highest values. All extractable B values were related to organic matter while only CaCl₂-extractable B correlated with total B. Generally total and extractable B values were higher in the top soils than in the subsoils.     

用体外免疫法建立人—人抗流行性乙型脑炎病毒杂交瘤细胞株

利用单克隆抗体(McAb)进行病毒病的治疗是人们所关心的一个重大课题。 流行性乙型脑炎(乙脑)是一种严重威胁人民健康的急性传染病,病死率高,后遗症严重。国内外目前尚无特效疗法。陈伯权等用乙脑病毒皮下或腹腔感染3周龄小白鼠24、48小时及5天后,分别用乙脑病毒51-8McAb进行治疗,平均治愈率分别为78％、73％及22％。     

Nucleotide and deduced amino acid sequence of bovine adrenal medulla chromogranin B (secretogranin I)

1. A novel 1745-dalton pyroglutamyl peptide (BAM-1745)6 was recently isolated and characterized from bovine adrenal medulla chromaffin granules. Its amino acid sequence was found to be 93% identical to residues 580-593 of human chromogranin B (secretogranin I). 2. Based on this sequence a degenerate oligonucleotide probe was synthesized and used to identify a 2.4-kb bovine adrenal medulla chromogranin B cDNA. 3. The deduced polypeptide is 647 amino acids long and begins with a putative signal sequence of 20 residues as in the human, rat, and mouse proteins. Also conserved in the bovine protein is a tyrosine residue which may be sulfated, two N-terminal cysteines, and many paired basic amino acids which may serve as sites of posttranslational processing. The peptide BAM-1745 is flanked by paired basic amino acids and therefore is most likely a product of posttranslational processing. Bovine chromogranin B is 67, 58, and 58% identical to the human, rat, and mouse chromogranin B proteins, respectively. 4. The carboxyl terminus of bovine chromogranin B, including BAM-1745, was found to be the most conserved region of the polypeptide and may identify it as an important functional domain.     

Enzyme-linked immunosorbent assays for the measurement of blood group A and B glycosyltransferase activities

ELISA assays have been developed for (1–3)N-acetylgalactosaminyltransferase (blood group A transferase) and (1–3)galactosyltransferase (blood group B transferase) activities. In these assays, microtitre plates coated with the bovine serum albumin conjugate of a synthetic Fuc1–2Gal-R acceptor substrate are incubated with the appropriate nucleotide donor (UDP-GalNAc or UDP-Gal) and human serum as the enzyme source. The resulting trisaccharide products Fuc1–2(GalNAc1–3)Gal-R-BSA or Fuc1–2(Gal1–3)Gal-R-BSA are detected and quantified with monoclonal antibodies selected not to cross-react with the substrate structure. With less than a microliter of human serum, product formation is proportional to enzyme concentration and to time of incubation of up to 90 min.     

Clerodane diterpenoids from the roots of Portulaca pilosa

Three trans-clerodane diterpenoids, pilosanol A, B and C, the last compound being a glucoside, have been isolated from the roots of Portulaca pilosa. They show a marked contrast in skeletal type with the constituents of aerial part. Evolutionary changes in the biosynthetic abilities of Portulaca species is discussed.     

Requirements for plant regeneration from protoplasts of the shrubby ornamental honeysuckle,Lonicera nitida cv. Maigrun

Leaf protoplasts of axenic shoot cultures of Lonicera nitida cv Maigrun underwent sustained division to give multicellular colonies (microcalli) on a modified, ammonium-free MS (Murashige & Skoog) medium containing 0.5 mg l^-1 NAA (1-naphthaleneacetic acid), 1.0 mg l^-1 BAP (6-benzylaminopurine) and 150 mg l^-1 casein enzymatic hydrolysate. Callus was produced upon transfer of cell colonies to MS medium with 2.0 mg l^-1 NAA and 0.2 mg l^-1 BAP. About 110 days from isolation protoplast-derived shoots were regenerated on a half-strength MS medium with 0.01 mg l^-1 NAA, 5.0 mg l^-1 BAP, 0.5 mg l^-1 zeatin and a complex mixture of group B vitamins. The replacement of such mixture by 250 mg l^-1 casein enzymatic hydrolysate promoted rhizogenesis in calli, with shoot buds being subsequently regenerated from the protoplast-derived roots. Micropropagation of protoplast-derived shoots (of either origin) was difficult, due to a strong apical dominance, but could be accomplished by transferring single-node explants to half-strength MS medium with 1.5 mg l^-1 BAP. Such shoots were, in turn, successfully rooted and transferred to the glasshouse where they completed acclimatization.Abbreviations BAP 6-benzylaminopurine - CPW Power et al. (1989) medium - 2,4-D 2,4-dichlorophenoxyacetic acid - FDA fluorescein diacetate - F.P.E. final plating efficiency - f.wt. fresh weight - IAA 4-indole-3yl-acetic acid - IBA 4-indole-3yl-butyric acid - I.P.E. initial plating efficiency - MES 2-N-morpholinoethane sulfonic acid - M.P.E. intermediate plating efficiency - MS Murashige & Skoog (1962) medium - NAA 1-naphthaleneacetic acid - PVP-10 polyvinylpirrolidone - Av MW 10,000, TIBA 2,3,5-tri-iodobenzoic acid - Z zeatin