屋顶长生花的离体培养和植株再生

1植物名称屋顶长生花(Sempervivum tectorum). 2材料类别叶片. 3培养条件基本培养基为MS培养基.(1)诱导愈伤组织培养基:MS 2,4-D 2.0 mg·L-1(单位下同) 6-BA 2.0;(2)诱导分化培养基:MS 6-BA 2.0 NAA0.2 GA3 0.4;(3)继代增殖培养基:MS 6-BA0.3～4;(4)生根培养基:1/2MS NAA 0.2 IAA 1.0 0.3%活性炭.以上培养基均加入0.8%琼脂、4.5%蔗糖,pH 5.8.培养温度为(21±1)℃,光照度2500lx,光照时间14 h·d-1.     

Glucocorticoids increase beta-adrenoceptors on human intact lymphocytes in vitro

A modification of beta-adrenoceptor binding has been observed in different human and animal tissues after glucocorticoid administration. In this study we observed that hydrocortisone increased human intact lymphocyte beta-adrenoceptors labelled with 3H-dyhydroalprenolol in vitro, in physiological and pharmacological concentrations. In saturation experiments hydrocortisone (10(-6)M) significantly raised beta-adrenoceptor Bmax and KD. Intact living lymphocytes seem to be a useful model for further investigation in man of the regulation of beta-adrenoceptors by glucocorticoids in physiological conditions.     

The in vitro micronucleus test on isolated human lymphocytes

The in vitro micronucleus test was performed on isolated human lymphocytes using the cytokinesis-block technique with and without a rat liver metabolizing system. Positive control substances were used to evaluate this test: a direct agent (vincristine) requiring no metabolic activation, and three promutagens (cyclophosphamide, benzo[a]pyrene and dimethylbenz[a]anthracene). All of them, when compared with controls, caused a significant increase in micronucleus frequency, with a clear dose response. Five compounds were then tested in this in vitro micronucleus test: safrole, azathioprine, procarbazine, diethylstilbestrol and o-toluidine. The chemicals were examined with and without exogenous metabolic activation. Of these five compound, o-toluidine was found to be a marked direct genotoxic agent and azathioprine gave positive results with or without metabolic activation (a better response was noted without the addition of S9 mix). Diethylstilbestrol gave conflicting results and was considered inconclusive. Two chemicals, safrole and procarbazine, were found to be non-genotoxic in this test system, whatever the protocol used.     

Effects of high-frequency electromagnetic fields on human lymphocytes in vitro

Human peripheral lymphocytes were incubated in the presence of high-frequency electromagnetic fields of 380, 900 and 1800 MHz. The measured endpoints were cell cycle progression and the frequencies of sister-chromatid exchanges. No differences between treated and control cultures could be found.     

Cytotoxicity of tin on human peripheral lymphocytes in vitro.

The comparative effects of inorganic and organic tin compounds on chromosomes were assessed in human peripheral blood lymphocytes of healthy donors 20-40 years of age. The endpoints observed were chromosomal abnormalities, sister-chromatid exchanges (SCEs) and cell cycle kinetics. The maximum concentrations which reduced the replicative index by about 50%, of stannic chloride and trimethyltin chloride were 40 micrograms and 2 micrograms per culture respectively. The tested doses were 20 micrograms and 10 micrograms of stannic chloride and 1 microgram and 0.5 microgram of trimethyltin chloride. Both doses of stannic chloride induced a much higher frequency of chromosomal abnormalities (P less than 0.05-P less than 0.001) and a greater reduction of cell cycle kinetics than the corresponding relative doses of trimethyltin chloride. The frequencies of SCEs/cell induced by the latter were, however, slightly higher than those induced by the former.     

Interaction of human lymphocytes and viruses in vitro.

Interaction between phytohaemagglutinin (PHA) stimulated human lymphocytes and two DNA viruses (adenovirus type 5 and herpes simplex virus type 1) considered to be closely connected with lymphoid tissues has been studied. The fate of the same viruses was investigated also in non-stimulated separated lymphocytes for comparative purposes. To elicit this interaction infectivity titrations, immunofluorescent technique and electron microscopy were used. The production of viral antigens was investigated by complement fixation. It has been shown that in PHA-stimulated lymphocytes from peripheral blood of healthy donors adenovirus type 5 is capable to replicate in its infectious form. Prolongation of the interval between stimulation and infection of cells significantly influenced the dynamics of replication. Non-stimulated lymphocytes produced antigens but no infectious particles.     

Cytogenetic effects of cyclophosphamide on human lymphocytes in vivo and in vitro

A comparative study of cytogenetic effects in human lymphocytes caused in vivo by cyclophosphamide (CP) after intravenous injection and in vitro by exposure of plasma of the same patients was carried out. It was found that the frequency of induced chromosome aberrations (CA) and sister-chromatid exchanges (SCE) increased linearly for SCE and exponentially for CA within the 'dose' of alkylating activity of CP metabolites. Parameters of 'cytogenetic effect-dose' in vivo and in vitro coincided. The intensity of cytogenetic effects varied between individuals.     

Studies on the interaction between mitogens and human lymphocytes in vitro

The initial events in interaction between mitogens and lymphocytes were studied with kidney bean phytohemagglutinin (PHA-W), concanavalin A (Con A), kidney bean leucoagglutinin (LA) and antilymphocyte globulin (ALG). The lectins were characterized by disc electrophoresis and immunoelectrophoresis. LA was found to be homogeneous while PHA-W was separated in three bands and showed two antigenic components. When lymphocytes were incubated with mitogen for a short time (1 h) and in experiments according to the described technique for transfer of mitotic stimulation between lymphocytes it was found that the binding of PHA-W to the cell differed from that of LA and ConA. In binding experiments with labelled mitogens PHA-W was found to have twice as many binding sites per cell as LA and ConA, although similar affinity constants were found. The relationship between mitogens and lymphocyte receptors was studied in lymphocytes incubated with two mitogens simultaneously for a short period. Both inhibitory and synergistic effects were found. The results indicate that (a) mitogens with different receptor specificities give a synergistic response; (b) mitogens reacting with the same or closely related receptors are inhibitory to each other. The interpretation of the binding of PHA-W to lymphocytes and of the inhibitory and synergistic effects of mitogens are discussed.     

In vitro cytogenetic studies of cypermethrin on human lymphocytes

Assessment of cytotoxicity and response to external factors like pesticides were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) or MTT assay, which measures mitochondrial metabolism in the entire cell culture and provides information about the percentage of cell survival. Utilizing the MTT assay, the cytotoxicity of cypermethrin was determined on lymphocyte cultures from human peripheral blood samples, the short-term lymphocyte cultures were incubated with various aliquots of the cypermethrin and the LC50 was found to be 33.6 microM. Lymphocytes treated with low-doses (1/10 of LC50) of cypermethrin showed an increase in the frequency of chromosomal aberrations and found to be significant. Karyotype analysis revealed more satellite associations and chromosomal breaks in cypermethrin treated samples. Low-doses of the pesticide also induced single-strand breaks in the DNA as assessed by comet assay. The pesticide caused increase in the comet tail length with increase in pesticide concentration, implicating genotoxicity in somatic cells. It is concluded that In vitro assays could give important information of the mechanism of toxicity at low dosages and impact on genetic material of human origin.     

Effect of human leukocyte interferon on human lymphocytes in vitro: cytogenetic studies

Mitogen-stimulated lymphocytes from 8 healthy donors were exposed to interferon, and cytogenetic studies were preformed. The response of lymphocytes to the mitogens phytohemagglutinin (PHA), concanavalin A (con A) and pokeweed mitogen (PWM) was inhibited by interferon, whereas an increased number of structural chromosomal aberrations was not detected. Further investigations of the cytogenetic effects of interferon are needed.     

Chromosome-damaging effects of heraclenin in human lymphocytes in vitro

Heraclenin, a furocoumarin with an epoxide group in its side chain, was analyzed to see if it induced structural chromosome aberrations and sister-chromatid exchanges (SCEs) in human lymphocytes in vitro. The results were compared directly with those of imperatorin, which differs from heraclenin only in lacking an epoxide group. An equally strong clastogenic effect was found for both heraclenin and imperatorin: the number of metaphases with breaks was increased in both cases by approximately a factor of 6. Heraclenin produced a considerable dose-dependent increase in the SCE rate, i.e., by about 60 induced SCEs/metaphase, whereas imperatorin induced only about 4 SCEs/metaphase. The results are discussed with respect to the occurrence of structural aberrations, which are primarily due to the basic furocoumarin structure itself, whereas the large increase in the SCE rate produced by heraclenin is most probably significantly influenced by its epoxide group.     

Genotoxic effects of potassium bromate on human peripheral lymphocytes in vitro

The aim of this study was to investigate the genotoxic effects of potassium bromate, which is used as a bleaching agent in flour, on human peripheral blood lymphocytes in vitro by sister chromatid exchange (SCE), chromosomal aberrations (CA) and micronucleus (MN) tests, and also to determine whether it has any genotoxic potential for humans. Cells were treated with 400, 450, 500, 550 microg/ml concentrations of potassium bromate for 24 and 48 h. The SCE frequencies showed an increase after both treatment periods, however, the differences between the treated cells and the control groups were found to be statistically significant only for the 48-h treatment. In addition, potassium bromate statistically significantly induced CA after the 24-h and 48-h treatment periods. Strikingly, potassium bromate induced CA as much as the positive control, mitomycin-C (MMC). Furthermore, potassium bromate decreased both the cell proliferation index (PI) and the mitotic index (MI). Although micronucleus formation was induced by potassium bromate during the 24-h treatment period in a dose-dependent manner, only the doses 500 and 550 microg/ml yielded statistically significant results. In contrast, MN formation was significantly induced at all doses during the 48-h treatment period. These in vitro results provide important evidence about genotoxicity of potassium bromate on a human cell culture system.