[Application of intermittent flap opening in L-shaped surgical incision of calcaneal fracture].

OBJECTIVE: To explore clinical effect of intermittent flap opening technique in L-shaped incision of calcaneal fracture. METHODS: From January 2017 to January 2019, 48 patients with Sanders typeⅡ to Ⅳ calcaneal fractures were treated by open reduction and internal fixation. According to different flap opening techniques, the patients were divided into control group and observation group, 24 patients in each group. In observation group, there were 17 males and 7 females, aged from 20 to 60 years old with an average of(45.12±9.56) years old;7 patients were typeⅡ, 10 patients were type Ⅲ and 7 patients were type Ⅳ according to Sanders classification;3 patients were C0, 16 patients were C1 and 5 patients were C2 according to Tscherne-Gotzen soft-tissue assessment;treated with intermittent flap technique. In control group, there were 19 males and 5 females aged from 20 to 60 years old with an average of (47.32±10.67) years old;7 patients were typeⅡ, 11 patients were type Ⅲ and 6 patients were type Ⅳ according to Sanders classification;2 patients were C0, 18 patients were C1 and 4 patients were C2 according to Tschemc-Gotzen soft-tissue assessment;treated with static flap opening technique. Operation time, flap retraction time, changes of Böhler angle and Gissane angle before and after operation at 3 days, and occurrence of incision complications were observed and compared between two groups. RESULTS: All patients were followed up from 3 to 6 months with an average of(4.52±1.01) months. There were no significant differences in operation time, changes of Böhler angle and Gissane angle before and after operation at 3 days between the two groups(P>0.05);there was statistical difference in flap retraction time between two groups(P<0.05). Occurrence of incision complications in observation group was significantly lower than that in control group (P<0.05). CONCLUSION: Intermittent flap opening technique is superior to static opening technique in reducing incision complications of lateral "L" approach of calcaneus. Single Kirschner wire opening does not affect the exposure, reduction and fixation of fracture during operation.

[Selective U-shaped osteotomy of lateral tibial condyle for the treatment of collapse and comminuted fracture of lateral tibial plateau].

OBJECTIVE: To explore methods and clinical effects of selective U-shaped osteotomy of lateral tibial condyle in treating collapse and comminuted fracture of lateral tibial plateau. METHODS: From January 2014 to October 2019, 15 patients with collapse and comminuted fracture of lateral tibial plateau were treated by selective U-shaped osteotomy of lateral tibial condyle, including 9 males and 6 females. The age of patients ranged from 25 to 70 years old, with an average age of (38.5±7.7) years old. According to ABC classification of condyle fracture of tibial plateau lateral, there were 2 cases of type A, 6 cases of type B, 4 cases of type BC and 3 cases of type C. Five patients were combined with medial plateau fracture, 8 patients were combined with left knee fracture and 7 patients of right knee fracture. The time of treatment after injury ranged from 1 day to 14 days with an average of (3.4±1.2) days. CT of all patients showed that lateral tibial plateau collapsed more than 2 mm, more than 2 pieces of bones were crushed and broken, and lateral tibial condyle cortex was intact. At follow-up of 12 months after operation, Rasmussen's anatomical grading system was used to evaluate fracture reduction. Rasmussen's functional grading system were used to evaluate knee joint function. RESULTS: Selective U-shaped osteotomy was successfully complated in 15 patients at one time, and operation time ranged from 55 to 110 min, with an average time of (85.6±20.0) min. The lateral plateau operation ranged from 20 to 60 min with an average time of(30.5±10.5) min. All patients were followed up for 12 to 24 months with an average of (14.6±2.5) months. Fracture healing time was 12 to 24 weeks, with an average of (13.6±3.6) weeks. At follow-up 12 months after operation, by Rasmussen's grading system, anatomical score of knee joint ranged from 14 to 18 points, with an average score of (17.5±0.3) points, of which 13 cases were excellent and 2 cases were good. The functional score ranged from 13 points to 30 points, with an average score of (26.8±2.5) points. Among them, 12 cases were excellent, 1 case was good, 2 cases were fair. Two patients suffered 2 mm and 4 mm loss of lateral tibial plateau, 1 case of knee joint 5 ° valgus, 1 case of stiff joints (10 ° to 100 °). No common peroneal nerve injury, important vascular injury, postoperative infection, internal fixation failure and other serious complications was found. CONCLUSION: The use of selective lateral tibial condyle "U"- shaped osteotomy approach is an effective and reliable method to treat the collapse and comminuted fracture of the lateral tibial plateau. It has the advantages of simple surgical incision, direct fracture exposure, accurate repositioning and fixation, short operation time and few complications.

Fates of donor and recipient mitochondrial DNA during generation of interspecies SCNT-derived human ES-like cells.

To investigate nuclear donor and cytoplast recipient mitochondria fate and their effects on generation of interspecies somatic cell nuclear transfer (iSCNT)-derived human embryonic stem (ES)-like cells, iSCNT embryos were reconstructed between enucleated goat oocytes and human neural stem cells (hNSCs). A total of 10.74% cleaved embryos (13/121) developed to blastocyst stage. One typical primary ES-like (tpES-like) colony and two nontypical primary ES-like (non-tpES-like) colonies designated as non-tpES-like cell-1 and non-tpES-like cell-2, respectively, were obtained from the inner cell masses of iSCNT blastocysts. The tpES-like cells expressed ESC markers. Both human and goat mtDNA could be detected in the embryos at 2-8-, 16-32-cell, and blastocyst stages, and in tpES-like colony and two non-tpES-like colonies. Human mtDNA copies per cell from embryos at two- to eight-cell stage to the three colonies maintain almost its original level, whereas 2.88 x 10(5) goat mtDNA copies per oocyte decreased to 10.8 copies per tpES-like cell, 493 copies per non-tpES-like cell-1, and 77.6 copies per non-tpES-like cell-2, resulting in 43.75% (8.4/19.2), 1.24% (6.2/499), and 14.63% (13.3/90.9) mtDNA content in tpES-like cell, non-tpES-like cell-1, and non-tpES-like cell-2 was that of nuclear donor, respectively. Human-specific Tfam and Polg mRNA could be detected in cells of the three colonies. However, tpES-like colony failed to be passaged. The mRNA level of CoxIV encoded by nuclear donor in tpES-like cell was higher than that in non-tpES-like cell, but significantly lower than that of human ESC, suggesting proper nuclear-cytoplasmic communication would not be established in tpES-like cells. Thus, the data suggest that (1) goat oocytes could reprogram human neural stem cells (hNSCs) into embryonic state and further support the inner cell mass (ICM) of iSCNT blastocyst to form tpES-like colony; (2) nuclear donor mtDNA could be replicated and maintain its original level during the reduction of recipient mitochondrial DNA copies, (3) nuclear-cytoplasmic communication and recipient mtDNA copies might affect the derivation of iSCNT-derived ES-like cells.

Isolation and characterization of human anti-VEGF165 monoclonal antibody with anti-tumor efficacy from transgenic mice expressing human immunoglobulin loci.

The purpose of this study was to prepare a fully human anti-VEGF (vascular endothelial growth factor) monoclonal antibody with anti-tumor activity from five-feature mice which express human immunoglobin loci. Four hybridomas secreting mAb stably were isolated successfully. Some characters such as isotypes, cross-reactivity, inhibition on the binding of hVEGF to VEGFR-2, dissociation constants and the idiotypic characteristic were determined. Proliferation of T24 and Ls-174-T cell line and nude mice bearing human colorectal cancer were used to evaluate therapeutic effects and safety of this mAb. Pharmacokinetics data shows the half life of this mAb was about 5 days after a single intravenous injection. These results suggest the fully human anti-VEGF mAb maybe safe and efficient for cancer treatment.

Different intervals of ovum pick-up affect the competence of oocytes to support the preimplantation development of cloned bovine embryos.

The objective of this study was to determine the effect of different frequencies of transvaginal ovum pick-up (OPU) on the quantity of recovered cumulus oocyte complexes (COCs) and subsequently the competence of matured oocytes to support the preimplantation development of cloned bovine embryos. The COCs were aspirated from the ovaries of 6 Chinese Holstein cows by transvaginal follicle aspiration twice a week (every 3 or 4 days) (Group I), every 5 days (Group II), once a week (every 7 days) (Group III), every 10 days (Group IV), and once every 2 weeks (every 14 days) (Group V). The developmental stages of the follicles were confirmed by the diameter of the dominant follicle (DF) and harvested COCs, and the dynamics of the follicular wave were clarified. In addition, extrusions of the first polar body (PB I) from the oocytes were observed at different time intervals after the initiation of in vitro maturation (IVM) to identify the appropriate culture time window for somatic cell nuclear transfer. Matured oocytes were used to produce cloned bovine embryos that were subsequently cultured in the goat oviduct. After 7 days, the embryos were flushed out, and the developmental rates of the blastocysts were compared among the five groups. The results showed that the aspirations of all follicles >or=3 mm in diameter (D1) induced and synchronized the dynamics of the follicular wave, and the subordinate follicles became atretic after 4 days (D5). Another follicular wave started between D7 and D10, and atresia in the subordinate follicles in the second follicular wave began on D14. The timing of meiotic progression (from the initiation of IVM to the extrusion of PB I) in the oocytes obtained by OPU was later than that of the oocytes obtained from the abattoir. Between 20 and 24 hr after the initiation of IVM, 20% of the oocytes extruded their PB I. Further, 80% (520/650) of the harvested COCs were arrested at metaphase II (MII) by 22 hr of the initiation of IVM and were used as cytoplast donors. The rates of development of the reconstituted embryos to the blastocyst stage were 23.1% (Group I), 15.0% (Group II), 10.9% (Group III), 4.9% (Group IV), and 29.0% (Group V). The results indicate that the developmental potential of follicles from the same living donors were different when different intervals of OPU were adopted and early atretic follicles from the second follicular wave had higher competence to support the early development of cloned bovine embryos.

[Knockout serum replacement improves establishment efficiency of C57BL/6J mouse embryonic stem cell line].

AIM: To eliminate the influence of serum on self-renewal of embryonic stem cells (ESCs), knockout serum replacement (KSR), a defined formulation, was used to replace serum for the establishment of C57BL/6J mouse ESC line. METHODS: C57BL/6J mouse blastocysts collected at 3.5 days post coitum (d.p.c.) were cultured in the medium supplemented with KSR. In control experiment, KSR was substituted by fetal bovine serum (FBS). When ESC line was established, the morphology of ESCs, the expression of alkaline phosphatase and oct-4, and the karyotype and differentiating ability of ESCs were analyzed. RESULTS: 13 blastocysts were cultured in the medium supplemented with KSR and one ESC line (MES-1) was established with a normal and stable XX karyotype after cultured for more than 20 passages, and then the high expression of alkaline phosphatase and oct-4 was detected. When cultured in suspension, MES-1 formed embryoid bodies. When inoculated subcutaneously into nude mice, MES-1 formed teratoma. After injected into ICR mouse blastocysts collected at 3.5 d.p.c., MES-1 incorporated into the inner cell mass of the host blastocyst and contributed to the development of a chimera. In control experiment, no ESC lines were cultured for more than 3 passages. CONCLUSION: KSR can be efficiently used to isolate and culture C57BL/6J mouse ESCs, which can eliminate traditional prescreening of FBS suitable for isolation and culture of ESCs.

Secondary SCNT doubles the pre-implantation development rate of reconstructed interspecies embryos by using cytoplasts of Sannen dairy goat ova.

The aim of this study was to investigate whether ova of Sannen goat could support the pre-implantation development of interspecies embryos constructed through somatic cell nucleus transfer (SCNT) embryos and whether secondary SCNT (SSCNT) could improve the pre-implantation development of those embryos. The primary SCNT (PSCNT) embryos were produced by using Sannen goat ovum cytoplasts as recipients and fibroblast cells, derived from human, rabbit and Boer goat skins, as nucleus donors. The blastomeres of 8 to 16 cells stage of PSCNT embryos were subsequently used as nucleus donor cells and Sannen goat ovum cytoplasts as recipients to evaluate the effect of SSCNT on the pre-implantation development rate of these reconstructed interspecies embryos. Our results indicate that the pre-implantation development rates of SSCNT embryos reconstructed using these three different blastomeres are almost twice of that of corresponding PSCNT embryos (human, 15.8% vs. 7.8%; rabbit, 27.9% vs. 12.5%; Boer goat 55.3% vs. 24.5%; P < 0.05 in all three cases). The time durations that embryos need for the serial events of remodeling and reprogramming to take place vary, depending on the animal species of nucleus donors. These data suggest that remodeling and reprogramming of donor nucleus may be enhanced by prolonged exposure of donor nucleus to maternal cytoplast. We conclude that Sannen goat cytoplast can support the pre-implantation development of embryos constructed with nuclei from various donors, including fibroblasts of human, rabbit and Boer goat; and the somatic nucleus derived from different species requires more time to achieve its reprogramming necessary for pre-implantation development.

Factors derived from mouse embryonic stem cells promote self-renewal of goat embryonic stem-like cells.

Goat embryonic stem (ES)-like cells could be isolated from primary materials-inner cell masses (ICMs) and remain undifferentiated for eight passages in a new culture system containing mouse ES cell conditioned medium (ESCCM) and on a feeder layer of mouse embryo fibroblasts (MEFs). However, when cultured in medium without mouse ESCCM, goat ES-like cells could not survive for more than three passages. In addition, no ES-like cells could be obtained when ICMs were cultured on goat embryo fibroblasts or the primary materials-whole goat blastocysts were cultured on MEFs. Goat ES-like cells isolated from ICMs had a normal karyotype and highly expressed alkaline phosphatase. Multiple differentiation potency of the ES-like cells was confirmed by differentiation into neural cells and fibroblast-like cells in vitro. These results suggest that mouse ES cells might secrete factors playing important roles in promoting goat ES-like cells' self-renewal, moreover, the feeder layers and primary materials could also influence the successful isolation of goat ES-like cells.

[Effect on development in NT embryos after transplantation of nuclei derived from transfected goat fetal fibroblasts suffering different treatments into enucleate eggs].

In order to improve the development rate of preimplantation nuclear transfer embryos (NT embryos) after transplanting nuclei derived from transgenic goat fetal cells, the donor fetal fibroblasts starved for 5 days in DMEM containing 0.5% FCS were divided into three groups and treated with different methods respectively before using as donor cell. Group 1 was frozen at -80 degrees C or in liquid nitrogen for several days or months. Group 2 was at first treated as the same as group 1, then cultured for 2-5 days in DMEM containing 10% FCS and starved for another 5 days subsequently. Group 3 was cultured for 2-5 days in DMEM containing 10% FCS and starved for another 5 days subsequently. The rate of G0/G1 phase cells from group 2 was 95.68% and significantly different from group 1's 88.66%. The rate of survival cells from group 2 was 99.9% and significantly different from group 1's 80.00% (P < 0.05).The morula- blastocyst stage NT embryos development rate of group 2 was 66.09% and significantly different from group 1's 22.00% and group 3's 50.51% (P < 0.05). All NT embryos of above three groups were transferred into synchronous oestrus recipients and the pregnant status of recipients was checked by B-mode ultrasound diagnosis after 35 days. The recipient pregnancy rate of group 2 was 45.83%, much higher than that of group 1(20.00%) and group 3 (29.58%). The result of this experiment showed that donor cells treated with freezing and two times starvation could significantly improve the rate of G0/G1 phase cells, the rate of survival cells, the NT embryos development rate and the recipient pregnancy rate.

[Establish a transgenic mice model harboring structural genes of hepatitis C virus].

OBJECTIVES: To establish an animal model of HCV transgenic mice to elucidate the pathogenesis of hepatitis C virus infection and function of the viral structural proteins. METHODS: Structural gene of HCV were amplified and recombined into eukaryotic expression vectors, pcDNA4HisMax and pMT/BiP/V5-His A, after their expressive activity was confirmed to detect the structural protein in the transfected COS7 and S2 cells by Western blot. The fertilized expression element, which contained CMV or pMT promoter, structural gene of HCV and polyadenylation signal sequence, was microinjected into 1736 C57BL/6 mouse fertilized ova. The ova were then replanted into the oviducts of 69 pseudopregnant recipient mice. RESULTS: Twenty-five recipient mice were impregnated and later produced 105 newborns; 49 of them died from unknown causes and 57 survived. After the specific HCV structural genes were identified by PCR and Southern blot hybridization, 26 founders were obtained; among them 10 were stable expression mice and 16 were the inducible ones. The rate of founders developed from implanted embryos was only 1.50%. Through hybridization with normal mice, 58 hybrid mice have been obtained at present. CONCLUSION: Two kinds of different transgenic mice of HCV were developed; one is of stable expression, and the other is inducible. This transgenic mice model may create an opportunity for studying the function of the structural gene of HCV and elucidate its pathogenicity.

Efficient differentiation of embryonic stem cells into neurons in glial cell-conditioned medium under attaching conditions.

Embryonic stem (ES) cells can differentiate into neurons in vitro, which provides hope for the treatment of some neurodegenerative diseases through cell transplantation. However, it remains a challenge to efficiently induce ES cells to differentiate into neurons. Here, we show that murine ES cells can efficiently differentiate into neurons when cultured in glial cell-conditioned medium (GCM) under attaching conditions without the formation of embryoid bodies. In comparison with murine embryonic fibroblast-conditioned medium, we found that GCM has a positive effect on limiting the generation of non-neuronal cells, such as astrocytes. In addition, compared with suspension conditions, attaching conditions delay the differentiation process of ES cells.

Transfer of an expression YAC into goat fetal fibroblasts by cell fusion for mammary gland bioreactor.

Yeast artificial chromosomes (YACs) as transgenes in transgenic animals are likely to ensure optimal expression levels. Microinjection of YACs is the exclusive technique used to produce YACs transgenic livestock so far. However, low efficiency and high cost are its critical restrictive factors. In this study, we presented a novel procedure to produce YACs transgenic livestock as mammary gland bioreactor. A targeting vector, containing the gene of interest-a human serum albumin minigene (intron 1, 2), yeast selectable marker (G418R), and mammalian cell resistance marker (neo(r)), replaced the alpha-lactalbumin gene in a 210kb human alpha-lactalbumin YAC by homogeneous recombination in yeasts. The chimeric YAC was introduced into goat fetal fibroblasts using polyethylene glycol-mediated spheroplast fusion. PCR and Southern analysis showed that intact YAC was integrated in the genome of resistant cells. Perhaps, it may offer a cell-based route by nuclear transfer to produce YACs transgenic livestock.

[Preparation and preliminary application of monoclonal antibody against recombinant human erythropoietin].

AIM: To prepare monoclonal antibody (mAb) against erythropoietin(EPO), characterize its biological properties and use it to purify the rhEPO from transgenic goat milk. METHODS: A crude rhEPO product was used as the antigen to immunize BALB/c mice for preparing mAbs against rhEPO. The mAbs were characterized by Western blot and indirect ELISA. Purified mAb 2E6 was coupled with pre-activated Sepharose 4B to prepare the immunoaffinity chromatography column for purifying the rhEPO from transgenic goat milk. RESULTS: Two hybridoma cell lines(1E7 and 2E6)were obtained. mAbs 1E7 and 2E6 were shown to be IgG1 and IgG2b respectively, and their light chains were both kappa. Western blot analysis confirmed that the two mAbs could bind to rhEPO. The immunoaffinity chromatography column could adsorb 70% of rhEPO in purifying the rhEPO from transgenic goat milk. CONCLUSION: Two hybridoma cell lines secreting anti-rhEPO mAbs were successfully established. The mAb-immunoaffinity chromatography column could be used to purify the rhEPO from transgenic goat milk.

[Expression of goat beta-casein gene targeting vector in mammary gland cell].

The study of mammary gland bioreactor is in the ascendant. In order to generate transgenic goats of well-controlled expression of exogenic genes, we constructed a human lactoferrin (hLF) gene targeting vector containing promoter, exon 1, intron1 and some of exon 2 (about 6.1 kb fragment) and exon 6 approximately 9 (about 3.3 kb fragment) of the goat beta-casein gene as well as hLF minigene, neo gene inserted into them and tk gene ligated to the 3' end of the construct. The 9.4 kb goat genomic sequences as homologous arms were initially amplified by PCR with local goat tissue DNA. The expression vector was named pBC-tk-neo-hlf. Then the recombinant plasmid pBC-tk-neo-hlf containing hLF minigene was transfected into mice mammary tumor cell line C127 by liposome, cell clones were selected with G418. After proliferating, the transfected cells were induced with insulin, luteotropic hormone and hydrocortisone. The result of Western-blotting analysis showed that the transfected cells can secrete hLF protein, and the recombinant protein expressed in cultured cell supernatant has the similar molecular weight as the native protein. The expression level detected by ELISA was 0.21 microg/mL. This result indicated that the targeting vector could efficiently direct the expression of hLF in mammary cells,and it confirmed the validity of the constructed vector. At the same time, C127 cell line proved to be useful for evaluating the regulation of a foreign gene expression in mammary gland specific expression vector.

[Preparation methods of nanocavity biomaterials with recognition specificity via template imprinting of proteins].

Nanocavity biomaterials with recognition specificity imprinted by using proteins as templates may successful serve as substitutes for antibodies, enzymes, and other native biological structures as well as cell bracket materials. It has numerous applications in biotechnology, medicine and so on. In this paper, the principle of template imprinting is introduced briefly, the specialty of template imprinting of proteins is analyzed, and the methods of template imprinting of proteins including protein entrapment, microbead surface imprinting, flat surface imprinting as well as the epitope are reviewed in details.

[Comparison of vitrification cryopreservation among different stages of mouse embryos].

The cryopreservation of different embryo stages collected from ICR, C57BL/6 and F1 of DBA*C57BL/6 was carried out by using vitrification method. The morphology, in vitro development and birth rates of these embryos were compared after frozen-thawed. The results showed that more than 75% of the morphology from 2-cell embryos to morula stages from different strains was normal, the normal morphology rates of 8-cell embryos being the highest, while those of blastulas being the lowest. The in vitro development rates became higher as the embryos developed. The morphology of in vivo and in vitro fertilized frozen 2-cell embryos showed no difference, but the development rate of in vivo fertilized frozen 2-cell embryos was significantly higher than that of in vitro ones. Embryos that underwent 3 times frozen-thawing remained normal morphology. The pregnant rate and birth rate of frozen 2-cell embryos after embryo transfer were 64% and 40% respectively, but lower than those of fresh 2-cell embryo transfer.

Generation and characterization of transgenic mice expressing tamoxifen-inducible cre-fusion protein specifically in mouse liver.

AIM: To establish transgenic mice expressing tamoxifen-inducible Cre-ERt recombinase specifically in the liver and to provide an efficient animal model for studying gene function in the liver and creating various mouse models mimicking human diseases. METHODS: Alb-Cre-ERt transgenic mice were produced by microinjecting the construct with Cre-ERt fusion gene of DNA fragments into fertilized eggs derived from inbred C57BL/6 strain. Transgenic mice were identified by using PCR and Southern blotting. Expression of Cre-ERt fusion gene was analyzed in the liver, kidney, brain and lung from F1 generation transgenic mice at 8 weeks of age by reverse transcription (RT)-PCR. RESULTS: Four hundred and fourteen fertilized eggs of C57 BL/6 mice were microinjected with recombinant Alb-Cre-ERt DNA fragments, and 312 survival eggs injected were transferred to the oviducts of 12 pseudopregnant recipient mice, 6 of 12 recipient mice became pregnant and gave birth to 44 offsprings. Of the 44 offsprings, two males and one female carried the hybrid Cre-ERt fusion gene. Three mice were determined as founders, and were back crossed to set up F1 generations with other inbred C57BL/6 mice. Transmission of Cre-ERt fusion gene in F1 offspring followed Mendelian rules. The expression of Cre-ERt mRNA was detected only in the liver of F1 offspring from two of three founder mice. CONCLUSION: Transgenic mice expressing tamoxifen-inducible Cre-ERt recombinase under control of the liver-specific promoter are preliminary established.

Conditional gene activation in cultured hepatocytes using a ligand-dependent chimeric Cre recombinase.

By combining liver-specific promoter and a chimeric Cre recombinase, conditional gene activation could be finely achieved in hepatocytes at selected time points. To this end, the expression vector of Cre-ERt under the control of the mouse albumin gene promoter/enhancer, alb-Cre-ERt, was constructed, and transfected into engineering BRL (Rat hepatocytes) and BRK (Rat kidney) reporter cells which carries a chromosomally integrated 'floxed' beta geo gene, which is inserted between the promoter and the human alkaline phosphatase( hAP) reporter gene, thereby preventing hAP reporter gene transcription, respectively. After treatment with 1 micromol/L 4-hydroxytamoxifen(4-OHT), a proportion of hAP staining positive cells were detected by hAP staining. It was further confirmed that 'floxed' beta geo cassette was removed by Cre excision by using PCR analysis of cellular DNA. No background recombinase activity could be detected in the absence of 4-OHT. Moreover, no hAP-positive cells could be detected in BHK cells untreated or treated with 4-OHT. These data suggested that alb-Cre-ERt expression vector was constructed successfully, and 4-OHT could induce Cre-mediated recombination only in hepatocytes expressing Cre-ERt, thereby activating a stably integrated hAP reporter gene. This provides a further foundation for producing transgenic mice expressing such an 4-OHT inducible Cre recombinase specifically in mouse liver.

[Study on the cloning goat by cross-breed somatic cell nuclear transfer].

UNLABELLED: Shaneng goat is a famous milking species. Boer goat is world famous goat breed for creophagism. In this study, we evaluated the development potential of adult Boer goat's somatic nuclei after nuclear tansfer (NT) into enucleated MII oocytes of the Shaneng goat. Somatic donor cells were obtained from two different sources: 1) adult granulosa cells (GCs) and 2) adult skin fibroblasts (FCs). The reconstructed embryos that developed to morula or blastocyst stage in vivo were transferred to 38 synchronized recipient. CONTROL: Somatic donor fibroblast cells were obtained from a fetal at 35 day. In the same way the reconstructed embryos were directly transferred to synchronized recipient of Shaneng goats. (1) Experimental group: NT embryos derived from GC and FC developed into morulas and blastocysts at a frequency of 46.8% and 31.4% respectively. Fifty-two NT morula and blastocyst stage embryos were transferred in to 38 recipients, Three of which were confirmed to be pregnant (7.9%). All pregnancies were not maintained to term. (2) CONTROL group: 136 NT embryos were transferred in to 14 recipients, Six of which were confirmed to be pregnant (42.9%). Four of those were maintained to term. Four recipients delivered four male kids (2.9% of embryos transferred). One male kid died at birth, the dead lamb shows as "large offspring syndrome". the others appeared health and normal. DNA analysis confirmed that those kids were genetically identical to their donor. These results demonstrated that Shaneng goat somatic cells could direct normal development and Shaneng goat oocyte cytoplasm supported development of preimplantation embryos produced by NT of somatic cell nuclei from Boer goat.

[Nano-structured scaffold materials used in tissue engineering].

Micro- and nano-structured surfaces of scaffold materials have important effects on cells' adhesion and proliferation. Nano-structured surfaces can improve cells' adhesion and biocompatibility of materials. The effects of nano-biomaterials on the development of tissue engineering and the methods of preparation of nano-biomaterials such as molecular self-assemble and template technology are discussed.