A specific inhibitor of lactate dehydrogenase overcame the resistance toward gemcitabine in hypoxic mesothelioma cells,and modulated the expression of the human equilibrative transporter-1

ABSTRACT

Malignant pleural mesothelioma (MPM) is a very hypoxic malignancy, and hypoxia has been associated with resistance towards gemcitabine. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis. Therefore we investigated the combination of a new LDH-A inhibitor (NHI-1) with gemcitabine in MPM cell lines. Under hypoxia (O₂ tension of 1%) the cell growth inhibitory effects of gemcitabine, were reduced, as demonstrated by a 5- to 10-fold increase in IC₅₀s. However, the simultaneous addition of NHI-1 was synergistic (combination index < 1). Flow cytometry demonstrated that hypoxia caused a G1 arrest, whereas the combination of NHI-1 significantly increased gemcitabine-induced cell death. Finally, the mRNA expression levels of the human equilibrative transporter-1 (hENT1) were significantly down-regulated under hypoxia, but treatment with NHI-1 was associated with a recovery of hENT1 expression. In conclusion, our data show that hypoxia increased MPM resistance to gemcitabine. However, cell death induction and modulation of the key transporter in gemcitabine uptake may contribute to the synergistic interaction of gemcitabine with the LDH-A inhibitor NHI-1 and support further studies for the rational development of this combination.     

Mutations in the E1a gene of type 5 adenovirus result in oncogenic transformation of Fischer rat embryo cells

Transformation of a specific clone of Fischer rat embryo (CREF) cells with wild-type 5 adenovirus (Ad5) or the E1a plus E1b transforming gene regions of Ad5 results in epithelioid transformants that grow efficiently in agar but that do not induce tumors when inoculated into nude mice or syngeneic Fischer rats. In contrast, CREF cells transformed by a host-range Ad5 mutant, H5hrl, which contains a single base-pair deletion of nucleotide 1055 in E1a resulting in a 28-kd protein (calculated) in place of the wild-type 51-kd acidic protein, display a cold-sensitive transformation phenotype and an incomplete fibroblastic morphology but surprisingly do induce tumors in nude mice and syngeneic rats. Tumors develop in both types of animals following injection of CREF cells transformed by other cold-sensitive Ad5 E1a mutants (H5dl101 and H5in106), which contain alterations in their 13S mRNA and consequently truncated 289AA proteins. CREF cells transformed with only the E1a gene (0-4.5 m.u.) from H5hrl or H5dl101 also produce tumors in these animals. To directly determine the role of the 13S E1a encoded 289AA protein and the 12S E1a encoded 243AA protein in initiating an oncogenic phenotype in adenovirus-transformed CREF cells, we generated transformed cell lines following infection with the Ad2 mutant pm975, which synthesizes the 289AA E1a protein but not the 243AA protein, and the Ad5 mutant H5dl520 and the Ad2 mutant H2dl1500, which do not produce the 289AA E1a protein but synthesize the normal 243AA E1a protein. All three types of mutant adenovirus-transformed CREF cells induced tumors in nude mice and syngeneic rats. Tumor formation by these mutant adenovirus-transformed CREF cells was not associated with changes in the arrangement of integrated adenovirus DNA or in the expression of adenovirus early genes. These results indicate, therefore, that oncogenic transformation of CREF cells can occur in the presence of a wild-type 13S E1a protein or a wild-type 12S E1a protein when either protein is present alone, but does not occur when both wild-type E1a proteins are present.     

转基因植物的生态风险

转基因植物已在很多国家大规模商业化种植,并且取得了显著的经济效益。同时有关转基因植物潜在的生态风险已引起广泛的关注。本文从转基因植物人侵危害、对非靶标有益生物直接和间接的影响、害虫对抗虫转基因植物产生抗性、抗病毒转基因植物带来的潜在风险等方面论述了转基因植物可能潜在的生态安全性问题。     

宁夏枸杞的大、小孢子发生和雌、雄配子体发育

在幼小花药横切面上,每个角隅处可见一层拱形孢原细胞,其经过平周分裂形成初生造孢细胞、次生造孢细胞,发育为小孢子母细胞。减数分裂过程中胞质分裂为同时型。四分体为四面体型。成熟花粉粒含二细胞,具三孔沟型萌发孔。花药绒毡层由二部分组成:药壁区的绒毡层由初生壁细胞所产生,药隔区的由药隔细胞直接转化成,为双重起源,呈二型性,属分泌型。雌蕊由二个心皮构成二室子房,中轴胎座。倒生胚珠具单珠被、薄珠心,珠被绒毡层。胚囊发育为蓼型。在胚囊细胞分化后,组成胚囊的四种细胞继续发育,表现出各自的形态学变化。     

G_2期后期染色质结构及染色体高级结构形成的研究

用适量BrdU处理中华大蟾蜍外周血淋巴细胞,能以较高频率得到形态多样的染色质(体)结构。本文以两栖类和人类细胞为材料,采用Feulgen染色、Ag-NOR染色、DAPI荧光染色及放射自显影等方法,证实了其染色质性质,初步讨论了其产生原因,并将其命名为:“G,期后期染色质”。在此基础上,进一步从形态学角度初步分析了从G_2期后期到M期染色质转变为染色体的动态过程,提出不同染色体形成其高级结构是非同步的,有可能存在染色体包裹顺序的设想。     

Structural studies on hairy region of pectic polysaccharide from campion Silene vulgaris (Oberna behen)

Using enzymic digestion with pectinase, controlled Smith degradation and NMR-spectroscopy, some structural features of the hairy region of pectic polysaccharide termed silenan SV from the aerial part of campion Silene vulgaris (Moench) Garke (Oberna behen (L.) Ikonn) were elucidated.

Silenan was subjected to enzymic digestion with pectinase to furnish the polysaccharide fraction (SVP). The contained residues of -galacturonic acid (43%), arabinose, galactose and rhamnose as main constituents. The backbone of the hairy region of silenan was found to consist of -1,4-galactopyranosyl uronic acid and 2-O-glycosylated rhamnopyranose residues. The side chains contained linear regions of residues of -1,5-linked arabinofuranose and β-1,3-, β-1,4-linked galactopyranose. Silenan SV and its fragment SVP were subjected to Smith degradation to give fractions SVS and SVPS. These contain the residues of terminal and 2-substituted -arabinofuranose as well as residues of terminal, 3-, and 2,3-substituted β-galactopyranose. In addition, NMR-spectral data confirmed that the residues of -rhamnopyranose 2-O-glycosylated with the residues of -1,4-galactopyranosyl uronic acid of the backbone occurred in the core of SVPS and, therefore, in the backbone of silenan SV.

On the basis of data obtained, the hairy regions of silenan were suggested to contain mainly the linear chains of β-1,3-, β-1,4-galactopyranan and -1,5-arabinofuranan. The chains of -1,5-linked arabinofuranose, β-1,3- and β-1,4-linked galactopyranose were shown to be involved in the side chains of the hairy region having branching points at 2,3-substituted β-galactopyranose residues.     

Reversal of fluoride induced cell injury through elimination of fluoride and consumption of diet rich in essential nutrients and antioxidants

The objective of the present communication is to address the issues concerning reversal of fluoride induced cell injury and disease (i.e. fluorosis) through the elimination of fluoride and consumption of a diet containing essential nutrients and antioxidants. Humans afflicted with fluorosis, as a result of consuming fluoride contaminated water or food, have been investigated. Hospital based diagnostic procedure for early detection of fluorosis, through retrieval of history, clinical complaints, testing of blood, urine and drinking water for fluoride using ion selective electrode technology, along with X-ray of the forearm have been carried out. Confirmed cases of fluorosis were introduced to an intervention protocol consisting of (1) provision of safe drinking water with fluoride levels less than 1 mg/L and (2) counselling on nutritional supplementation with focus on adequate intake of calcium, vitamins C, E and antioxidants. The patients were monitored at frequent intervals up to one year and the results are reported. With a standardized early diagnosis, elimination of fluoride intake and supplementation of a diet rich in essential nutrients and antioxidants, we have shown that the fluorosis can be reversed.     

In-vitro evaluation of the antimicrobial activity of Bauhinia variegata,locally known as koiralo

Bauhinia variegata, commonly known as Koiralo is considered as medicinal plant in Nepal and India. The alcoholic extract of this plant was found to have antimicrobial activity against Bacillus subtilis (ATCC 6635) Pseudomonas aeruginosa (ATCC 27853), Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus (ATCC 29213) and Vibrio cholerae. The largest zone of inhibition (18 mm) was found to be exhibited against B. subtilis. For this organism the minimum bactericidal concentration (MBC) of the crude extract was 0.39 mg/ml. The extract was found to be more effective against gram-positive than gram-negative bacteria. The antimicrobial activity of the extract was found to be decreased during purification.     

Gradients of life-history variation: an intercontinental comparison of fishes

Multivariate analysis identified atwo-dimensional continuum of life-historyvariation among 301 fish species from Europe,North America, South America and the Atlanticand Pacific coasts of North America. The firstaxis was associated with larger body size,higher fecundity, delayed maturation, fewerreproductive events, and shorter breedingseason on one end and small size, lowfecundity, early maturity, multiplereproductive events per year, and prolongedbreeding season on the other. The second axiscontrasted fishes having larger eggs and moreparental care against fishes with the oppositesuite of traits.Phylogenetic affiliations of species wereapparent in the general patterns of ordinationof species within orders, indicatingevolutionary divergences in life-historypatterns. In fact, partitioning the variance oflife-history traits showed that taxonomic orderand latitude were the most important factorsand geographic region and habitat the least.Despite phylogenetic constraints, basiclife-history patterns showed consistencybetween distantly geographical regions,latitudinal ranges and basic adult habitats,indicating convergences in life-historypatterns. Although the basic life-historypatterns seemed repeatable among distantlyrelated taxa, geographical and latitudinalaffiliations were apparent. Species from SouthAmerica are skewed toward the opportunisticendpoint, whereas North American marine speciesare skewed toward the periodic endpoint of thetrilateral continuum model. Most of the fishspecies from South American data set came fromfluctuating environments, so an opportunisticstrategy of early maturation and continuousspawning permits efficient recolonization ofhabitats over small spatial scales. Incontrast, most species in the North Americanand European data sets came from seasonalhabitats that are nonetheless more hydrologicalstable, so a periodic strategy of delayingmaturation to attain large clutches enhancesadult survivorship during suboptimalenvironmental conditions and recruitment whenearly life stages encounter suitableenvironmental conditions. Similarly,latitudinal affiliations were also observed:opportunistic strategists more common intropical latitudes and periodic strategistsmore common in temperate and Arctic latitudes.