Evaluation of the cytoprotective effects of bovine lactoferrin against intestinal toxins using cellular model systems

This study investigated the effects of bovine lactoferrin (BLf) on the growth of different groups of bacteria in vitro. BLf showed a significant inhibitory effect on the growth of selected pathogens but not probiotics. BLf, in combination with probiotics, has the potential to influence the composition of the gut microflora via inhibition of intestinal pathogens with no significant effect on probiotic bacteria.     

AngⅡ和PKC对心肌细胞AngⅡ 1型受体的转录调节

利用体外培养的心肌细胞,观察血管紧张素Ⅱ（ＡｎｇⅡ）和蛋白激酶Ｃ（ＰＫＣ）在诱导ＡｎｇⅡ１型受体（ＡＴ１）基因表达及蛋白质代谢中的作用．研究结果表明：ＡｎｇⅡ可诱导ＡＴ１ｍＲＮＡ水平一过性下调,呈时间及剂量依赖性,１０ｎｍｏｌ／ＬＡｎｇⅡ刺激细胞６ｈ,引起ＡＴ１ｍＲＮＡ水平降低幅度最大,降至对照的５１．６％±９．５％,然后逐渐回升,２４ｈ恢复至对照水平．３０μｍｏｌ／ＬＨ－７（ＰＫＣ抑制剂）能阻断ＡｎｇⅡ诱导的ＡＴ１ｍＲＮＡ水平的下调．０．３μｍｏｌ／Ｌ的ＰＭＡ（ＰＫＣ激活剂）单独应用可诱导ＡＴ１ｍＲＮＡ水平下调达对照的４３％±８％,加入ＡＴ１拮抗剂ＤＭＰ８１１及Ｄｕｐ７５３均可阻断ＡｎｇⅡ诱导的ＡＴ１ｍＲＮＡ水平的下调．１０ｎｍｏｌ／Ｌ的ＡｎｇⅡ刺激心肌细胞９６ｈ可使蛋白含量降低至对照的７３．４％±５．６％,而加药持续刺激１４４ｈ可使蛋白含量较对照增加３３．８％±６．３％,Ｈ－７不能阻断ＡｎｇⅡ诱导的蛋白含量降低,但可有效地抑制蛋白含量的增加．以上结果提示：ＡｎｇⅡ对心肌细胞ＡＴ１基因的转录和细胞的蛋白代谢有调节作用,而ＰＫＣ则参与了ＡｎｇⅡ的这种调节作用     

Activation of Na+ /H+ exchange on rat preadipocyte plasma membrane and its role in cell proliferation and differentiation

An in vitro cultured rat perirenal preadipocyte (PA) was established as a model system to investigate the role of the intracellular pH (pHi) and of the Na~ /H~ exchanger during PA proliferation and differentiation, pH sensitive probe, 2' ,7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein(BCECF), was employed to measure the pHi of PA and to determine the Na~ /H~ exchange activity. The results showed that there was Na~ /H~ exchange activity in the plasma membrane of PA, FCS stimulated DNA synthesis measured by ~3H-TdR incorporation, and the activation of Na~ /H~ exchanger resulted in phi increase (nearly 0.2 pH unit) within 2 min. Ethyl-isopropyl-amiloride (EIPA), a specific Na~ /H~ exchange inhibitor, inhibited Na~ /H~ exchange activity and DNA synthesis. In the absence of serum insulin did not stimulate DNA synthesis but did induce PA differentiation characterized by the appearance of adiposome in the cell and the enhancement of glycerol-3-phosphate dehydrogenase (G_3PDHase) activity. Meantime, insu     

对大鲵自然种群在河北省(含京津)分布的质疑

在多年对野生动物种群调查的基础上, 通过检索河北省（含京津） 境内９２ 个市县, 自明清时代至今的近２００ 卷册地方志和走访有关学者, 分析并确定在河北省境内并无大鲵自然种群的分布。在部分地区偶见大鲵成体, 乃为幼鲵自繁殖地被偶然携带至该地而异地育肥的结果。     

牛背梁自然保护区种子植物多样性研究

对牛背梁自然保护区的种子植物多样性进行了研究。据统计,种子植物950种,隶属105科433属,其中,裸子植物4科8属9种,被子植物101科425属941种;木本植物372种,草本植物578种;珍稀濒危保护植物17种,资源植物丰富,分为药用,观赏,食用等10大类型,生态系统多样,按大的类型可划分为森林,灌丛,草甸,裸岩和农田,其中森林面积15055hm^2,占总面积的91.7%。是生态系统的主体。在此基础上,本文还提出了保护植物多样性应采取的对策。     

Inhibition of In Vivo HIV Infection in Humanized Mice by Gene Therapy of Human Hematopoietic Stem Cells with a Lentiviral Vector Encoding a Broadly Neutralizing Anti-HIV Antibody

Due to the inherent immune evasion properties of the HIV envelope, broadly neutralizing HIV-specific antibodies capable of suppressing HIV infection are rarely produced by infected individuals. We examined the feasibility of utilizing genetic engineering to circumvent the restricted capacity of individuals to endogenously produce broadly neutralizing HIV-specific antibodies. We constructed a single lentiviral vector that encoded the heavy and light chains of 2G12, a broadly neutralizing anti-HIV human antibody, and that efficiently transduced and directed primary human B cells to secrete 2G12. To evaluate the capacity of this approach to provide protection from in vivo HIV infection, we used the humanized NOD/SCID/γ_c^null mouse model, which becomes populated with human B cells, T cells, and macrophages after transplantation with human hematopoietic stem cells (hu-HSC) and develops in vivo infection after inoculation with HIV. The plasma of the irradiated NOD/SCID/γ_c^null mice transplanted with hu-HSC transduced with the 2G12-encoding lentivirus contained 2G12 antibody, likely secreted by progeny human lymphoid and/or myeloid cells. After intraperitoneal inoculation with high-titer HIV-1_JR-CSF, mice engrafted with 2G12-transduced hu-HSC displayed marked inhibition of in vivo HIV infection as manifested by a profound 70-fold reduction in plasma HIV RNA levels and an almost 200-fold reduction in HIV-infected human cell numbers in mouse spleens, compared to control hu-HSC-transplanted NOD/SCID/γ_c^null mice inoculated with equivalent high-titer HIV-1_JR-CSF. These results support the potential efficacy of this new gene therapy approach of using lentiviral vectors encoding a mixture of broadly neutralizing HIV antibodies for the treatment of HIV infection, particularly infection with multiple-drug-resistant isolates.While broadly neutralizing human immunodeficiency virus (HIV)-specific antibodies have the capacity to prevent or suppress HIV infection, they are rarely produced by infected individuals, thereby markedly compromising the ability of the humoral response to control HIV infection (reviewed in reference 28). The high degree of sequence variability in the gp120 structure limits the number of highly conserved epitopes available for targeting by neutralizing antibodies (40). In addition, HIV utilizes several mechanisms to shield the limited number of conserved neutralizing epitopes from the potentially potent antiviral effects of HIV envelope-specific antibodies (14). First, the envelope protein is heavily glycosylated, and the linkage of the most immunoreactive envelope peptide structures to poorly immunogenic glycans shields them from antibody binding (37). Second, exposure of neutralizing epitopes not protected from antibody binding by glycosylation is greatly reduced by trimerization of the gp120-gp41 structure (5). Third, susceptibility of other neutralizing epitopes to antibodies is greatly reduced by limiting their accessibility to antibody binding to the brief transient phase of conformational changes that occur only during binding of the envelope protein to its cellular receptors, CD4 and CCR5 or CXCR4 (41). These intrinsic structural features of gp120 greatly reduce the capacity of natural HIV infection or vaccination to generate broadly neutralizing antibodies able to prevent or control infection. Despite these constraints, rare human antibodies with broad anti-HIV neutralizing activity, i.e., 2G12, b12, 2F5, and 4E10, have been isolated (2).The capacity of passive immunization with neutralizing antibodies to prevent infection was suggested by challenge studies demonstrating that transferred neutralizing antibodies protected monkeys from infection by simian immunodeficiency virus (SIV) and simian-human immunodeficiency virus (SHIV) (15). These studies were extended to humans, including several studies that examined the effect of passive immunotherapy using 2G12, 2F5, and 4E10 on inhibition of HIV replication in infected individuals (20). Passive immunotherapy with a triple combination of 2G12, 2F5, and 4E10 delayed viral rebound after the cessation of highly active antiretroviral therapy (HAART), and activity of 2G12 was critical for inhibitory activity by this antibody combination (18). The key role of 2G12 in suppressing HIV replication was supported by the development of viral rebound in parallel with the emergence of HIV isolates resistant to neutralization by 2G12 (19).While HIV infection may be controlled by the lifelong treatment of HIV-infected individuals with periodic infusions of neutralizing-antibody cocktails every few weeks, this is not a practical or cost-effective therapeutic approach. Eliciting these antibodies by vaccination has not been successful. Therefore, we investigated whether we could circumvent the mechanisms that limit the endogenous production of broadly neutralizing HIV-specific antibodies using a molecular genetic approach to generate B cells that secrete these protective antibodies. In a proof-of-concept study, we examined the capacity of a single lentiviral vector to express the heavy and light chains of the 2G12 antibody, a well-studied anti-HIV human antibody that has broad neutralizing activity both against T cell line-adapted and primary HIV isolates (31). The 2G12 antibody was generated by applying murine/human xenohybridoma technology to establish human hybridoma cell lines from B cells isolated from HIV-infected individuals (16), and it targets the high-mannose and/or hybrid glycans of residues 295, 332, and 392 and peripheral glycans from residues 386 and 448 on gp120. In the current study we demonstrated that a lentiviral vector encoding the heavy and light chains of the 2G12 antibody reprogrammed B cells in vitro to secrete 2G12 with functional neutralizing activity. Furthermore, we demonstrated that the 2G12 lentiviral vector genetically modified human hematopoietic stem cells (hu-HSC), enabling them to differentiate in vivo into progeny cells that secreted 2G12 antibody that inhibited the development of in vivo HIV infection in humanized mice.     

The formation of improved tetraploid population of red crucian carp × common carp hybrids by androgenesis

Bisexual fertile diploid androgenetic individuals (A0) (2n=100) were formed by androgenesis. In this way, the diploid spermatozoa from male allotetraploid hybrids (AT) (4n=200) of red crucian carp (Carassius auratus red var.) (♀) × common carp (Cyprinus carpio L.) (♂) were used to fertilize the UV-treated hap- loid eggs of goldfish (Carassius auratus), and living androgenetic diploid fish were developed. The A0 became sexually mature at the age of 2 years, and they fertilized with each other to form their offspring (A1). In this study, we observed the chromosomal number, gonadal structure and appearance of A1 fish. The results are as follows: (1) In A1, there were 85% tetraploids (A1-4n), 10% triploids (A1-3n) and 5% diploids (A1-2n), suggesting that diploid A0 could produce diploid gametes. It was concluded that the formation of diploid gametes generated from diploid A0 was probably related to the mechanism of pre-meiotic endoreduplication. (2) Among A1, only A1-4n possessed normal ovaries and testes. The mature males of A1-4n produced white semen. Under the electron microscope, the head of diploid sperm generated by A1-4n was bigger than that of haploid sperm generated by red crucian carp. In the testes of the A1-4n, there were many mature normal spermatozoa with a head bearing plasma mem- brane and a tail having the typical structure of "9 2" microtubules. Between the head and the tail, there were some mitochondria. The ovaries of A1-4n developed well and mainly contained II, III and IV-stage oocytes. The IV-stage oocytes were surrounded by inner and outer follicular cells. The micropyle was observed on the oolemma of follicular cells. There were abundant yolks and plenty of endoplasmic reticulum in the cytoplasm of IV-stage oocytes. Because A1-2n and A1-3n were distant crossing diploid hybrids and triploid hybrids respectively, they possessed abnormal gonads, and no mature semen and eggs were observed. (3) Compared with allotetraploids, the A1-4n fish not only had advantages such as fast growth rate and strong resistibility but also showed some new good performances such as high ratio of body width to body length, smaller heads and shorter tails. These results indicated that an- drogenesis could produce bisexual fertile tetraploids and improve the shape of allotetraploid hybrids as well, which will be of great significance in both the cell genetics research and fish breeding.     

Involvement of nitric oxide in cerebroside-induced defense responses and taxol production in <Emphasis Type="Italic">Taxus yunnanensis</Emphasis> suspension cells

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells induced by a fungal-derived cerebroside and the signal role of NO in the elicitation of plant defense responses and taxol production. (2S,2′R,3R,3′E,4E,8E)-1-O-β-d-glucopyranosyl-2-N-(2′-hydroxy-3′-octadecenoyl)-3-hydroxy-9-methyl-4,8-sphingadienine at 10 μg/ml induced a rapid and dose-dependent NO production in the Taxus cell culture, reaching a maximum within 5 h of the treatment. The NO donor sodium nitroprusside (SNP) potentiated cerebroside-induced H₂O₂ production and cell death. Inhibition of nitric oxide synthase activity by phenylene-1,3-bis(ethane-2-isothiourea) dihydrobromide or scavenging NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide partially blocked the cerebroside-induced H₂O₂ production and cell death. Moreover, NO enhanced cerebroside-induced activation of phenylalanine ammonium-lyase and accumulation of taxol in cell cultures. These results are suggestive of a role for NO as a new signal component for activating the cerebroside-induced defense responses and secondary metabolism activities of plant cells. Taxol is a trademark of Bristol-Myers Squibb, Madison, NJ.     

Pharmacokinetic properties of crocin (crocetin digentiobiose ester) following oral administration in rats

This study investigated the pharmacokinetic properties of crocin following oral administration in rats. After a single oral dose, crocin was undetected while crocetin, a metabolite of crocin, was found in plasma at low concentrations. Simultaneously, crocin was largely present in feces and intestinal contents within 24h. After repeated oral doses for 6 days, crocin remained undetected in plasma and plasma crocetin concentrations were comparable to the corresponding data obtained after the single oral dose. Furthermore, the absorption characteristics of crocin were evaluated in situ using an intestinal recirculation perfusion method. During recirculation, crocin was undetected and low concentrations of crocetin were detected in plasma. The concentrations of crocin in the perfusate were reduced through different intestinal segments, and the quantities of drug lost were greater throughout the colon. These results indicate that (1) orally administered crocin is not absorbed either after a single dose or repeated doses, (2) crocin is excreted largely through the intestinal tract following oral administration, (3) plasma crocetin concentrations do not tend to accumulate with repeated oral doses of crocin, and (4) the intestinal tract serves as an important site for crocin hydrolysis.