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Biomedical subjects

Z Li

Publications and source records attributed to Z Li.

At least 1,405 records · Page 78Linked to original sources
PubMed1995

Mouse chick chimera: a new model to study the in ovo developmental potentialities of mammalian somites.

Chimeras were prepared by transplanting somites from 9-day post-coïtum mouse embryos or somitic dermomyotomes from 10-day post-coïtum mouse embryos into 2-day-old chick embryos at different axial levels. Mouse somitic cells then differentiated in ovo in dermis, cartilage and skeletal muscle as they normally do in the course of development and were able to migrate into chick host limb. To trace the behavior of somitic myogenic stem cells more closely, somites arising from mice bearing a transgene of the desmin gene linked to a reporter gene coding for Escherichia coli beta-galactosidase (lacZ) were grafted in ovo. Interestingly, the transgene was rapidly expressed in myotomal muscles derived from implants. In the limb muscle mass, positive cells were found several days after implantation. Activation of desmin nls lacZ also occurred in in vitro cultures of somite-derived cells. Our experimental method facilitates investigation of the mechanisms of mammalian development, allowing the normal fate of implanted mouse cells to be studied and providing suitable conditions for identification of descendants of genetically modified cells.

Animals↗
PubMed1995

A transient association of gamma-tubulin at the midbody is required for the completion of cytokinesis during the mammalian cell division.

gamma-Tubulin, a relatively new member of the tubulin gene family, is localized primarily at the centrosome throughout the mammalian cell cycle and may play a key role in nucleation of cellular microtubule assembly. A transient association of gamma-tubulin at the cytoplasmic bridge of telophase mammalian cells, the midbody, is recently documented. Using immunogold electron microscopy and serial section reconstruction analysis, we show here that the transiently associated midbody gamma-tubulin is localized at the minus ends of microtubules in the midbody structure. Using antisense RNA methods we also demonstrate that a selective depletion of transiently associated midbody gamma-tubulin causes an abortive cytokinesis due to a failure in the morphogenesis of the midbody structure.

Animals↗
PubMed1995

Selective induction of cell death in cancer cells by gallic acid.

Gallic acid (3,4,5-trihydroxybenzoic acid) is a naturally occurring plant phenol obtained by the hydrolysis of tannins and is know to show some pharmacological activities. In screening anti-cancer agents in traditional Chinese medicines, gallic acid was found to show cytotoxicity against all cancer cells that we examined in this study (IC50s: 4.8-13.2 micrograms/ml). Gallic acid was found to show cytotoxicity against primary cultured rat hepatocytes and macrophages, and lesser cytotoxicity against fibroblasts and endothelial cells. Cell death in dRLh-84 cells occurred within 6h after gallic acid treatment at a concentration of more than 20 micrograms/ml. A study of structurally related compounds suggested that the cytotoxicity shown by gallic acid was not a common feature in phenolic compounds, but was a fairly specific characteristic of gallic acid. That is, three adjacent phenolic hydroxyl groups of gallic acid were responsible for the cytotoxicity, and the carboxyl group was not responsible, but seemed to be implicated in distinguishing between normal cells and cancer cells.

Animals↗
PubMed1995

[The diagnosis and treatment of the epithelial salivary gland tumors in children and adolescents].

Sixty-six cases with epithelial salivary gland tumors in children and adolescents, who were less than 16 years old, were analized. Those cases accounted for 3.6% of all epithelial salivary gland tumors in our school. Twenty-five cases (37.9%) were benign tumors, among which pleomorphic adenoma was the most common. Forty-one cases (62.1%) were malignant tumors, in which mucoepidermoid carcinoma was the most common one. Three quarters of cases were in the group over 10 years old. Six cases were in the group less than 5 years old. Among them 5 cases were malignant tumors. The younger the children is, the more possible the malignant tumor is. Two cases with malignant tumors had the history of receiving radiotherapy because of the hemangiomas at the same locations. It indicates that the occurrence of the malignant tumors was related to radiotherapy before. The diagnosis, differential diagnosis and treatment of the tumors were discussed. The initial radical resection of the malignant tumors was emphasized.

Adolescent↗
PubMed1995

[Effect of processing on specific toxicity of radix Achyranthis bidentatae].

To activate Epstein-barr virus in Raji cells in vitro the lowest activation concentrations of ether extracts from Radix Achyranthis Bidentatae unprepared (I), stir-baked with wine (II) and stir-baked with salt (III) required were 0.8.20 and 0.16 micrograms/ml respectively. 5 microliters (equal to 250 mg herb weight)/ear of these extracts had inflammatory effect on mouse ear skin in 4 hours. Ethanol extract of I at concentration 0.04-125 mg/ml did not increase the chromosomal aberration rates in CHL cells. The decoctions of I, II, and III given orally at 15 g/kg x 3d showed no effect on micronucleus rates in mouse bone marrow. Ethanol extracts of I, II, and III at 10 g/kg x 10d did not show any evident antifertility action.

Animals↗
PubMed1995

A multiplicative random effects model for meta-analysis with application to estimation of admixture component.

A multiplicative random effects model is constructed for combining results from different studies. An EM algorithm is developed for the maximum likelihood estimator under the Empirical Bayes framework. The method is applied to estimation of the admixture component in admixed populations. The admixture estimates can be useful in genetic epidemiology and DNA fingerprinting.

Black or African American↗
PubMed1995

Antitumor effect of keto-diepoxides isolated from the fungus Nattrassia mangiferae.

A novel keto-diepoxide Sch 49209 and its derivative Sch 50672, produced by the fungus Nattrassia mangiferae, inhibited tumor cell invasion through an artificial basement membrane. These compounds, at nontoxic concentrations, inhibited invasion of HT-1080 cells in a dose-dependent manner. The IC50 values for Sch 49209 and Sch 50672 were 0.75 and 8 microM, respectively, when cells were incubated with drugs for 5 h. Sch 49209 inhibited both tumor cell invasion and cell motility to the same extent under conditions that did not cause any apparent cytotoxicity. Sch 4209 and Sch 50672, however, inhibited the growth of ras-transformed cells in a semisolid medium in a 5-day culture with IC50 values of 0.6 and 2.4 microM, respectively. They also inhibited the anchorage-dependent growth of pT24 cells in vitro with IC50 values of 0.5 and 0.9 microM for Sch 40209 and Sch 50672, respectively. Using the murine lung epidermoid carcinoma M27 cells implanted SC in mice as a model, we found both Sch 49209 and Sch 50672 inhibited the growth of this tumor at doses ranging from 2 to 10 mg/kg. These compounds also decreased the formation of spontaneous lung metastasis in this model. Sch 50672 inhibited the growth of human tumor xenografts, SW620 and A431, in athymic mode mice. Our data suggest that keto-diepoxides inhibit tumor growth and metastasis and that this activity may be due, in part, to anti-invasive activity.

Animals↗
PubMed1995

Astigmatism analysis after radial keratotomy.

Radial keratotomy without T-cutting was performed on 245 eyes of 124 patients with 6-8 months of post-operative follow-up. The results showed that post-operatively astigmatism was increased in 74 eyes (30.2%) with the increased range from +0.50 to +3.50DC, decreased in 27 eyes (11.0%) and not changed in 144 eyes (58.8%). The main causes of astigmatic change included microperforations, irregular incisions, incisions across the central optical zone and various depths of incisions, etc.

Adolescent↗
PubMed1995

[An analysis of severe complications of radial keratotomy].

Seven cases with severe complications threatening vision, including intraocular infection, corneal leucoma, secondary glaucoma, cataract and delayed rupture of corneal incisions following radial keratotomy (RK) were presented. The causes of the complications are related to corneal perforation and decreased tensile strength of the eye. Correct selection of indications, perfection of technique and instruments, avoidance of corneal perforation and prevention of infection are the measures to prevent severe complications following RK.

Adult↗
PubMed1995

Rabies viral antigen in human tongues and salivary glands.

Lingual and major salivary tissue samples from three cases of rabies were stained with the immunoperoxidase (ABC) technique. All tissue blocks had been embedded in paraffin 4-10 years before. The first antibody used was monoclonal antirabies nucleocapsin (N) mouse antibody (HAM). Four out of five pieces of tongue from two cases showed a large amount of granular staining indicating rabies antigen (RVAg) inside serous glandular cells, terminal nerves, muscle cells and covering epithelial cells including taste cells. In the tissue probes from the third case only minimal granular staining was found, probably due to complete absence of the serous gland. In contrast to the tongue, only a little weakly reacting material was found in 4 out of 9 probes of salivary gland, either in acini or in nerve fibres. The amount of RVAg is evidently much greater in the human tongue than in major salivary glands, whereas major salivary glands from infected dogs, foxes and skunks reportedly contain much RVAg. As the human tongue's serous gland appears to be a preferred location for RVAg, it may be a source of oral infection.

Adolescent↗
PubMed1995

Desmin transgene expression in mouse somites requires the presence of the neural tube.

Transgenic mice were used to study the effect of the neural tube on somite myogenesis. These mice express a transgene in which the 1 kb DNA 5' regulatory sequence of the desmin gene is linked to a reporter gene which codes for E. coli beta-galactosidase. In order to determine whether the developmental fate of cells, specifically the prospective myogenic population, in newly developed somites was pre-determined, newly formed somites were isolated from the caudal region of day 9.5 transgenic embryos and transplanted into 8.5 day non-transgenic host embryos. Even though the implanted somites were not oriented in the host embryos, all the specimens examined developed normally at the graft site forming a dermatome, myotome and sclerotome in the correct anatomical positions. The myotome even expressed the desmin transgene. In addition, we isolated the 3 most caudal somites, that is, the most recently developed somites, from day 9.5 transgenic embryos and maintained them on gelatin-coated coverslips in culture for up to 4 days. While these somite explants did not develop myoblasts, it was possible to induce myogenesis by introducing pieces of neural tube into the explant cultures. These results suggest that the developmental fate of cells within the newly formed somite is not predetermined, but is dependent on the microenvironment surrounding the developing somite.

Animals↗
PubMed1995

[Langerhans cells and human aural cholesteatoma].

Enzyme histochemical, immunohistochemical and ultramicroscopic analysis of 20 human aural cholesteatoma matrices revealed the presence of Langerhans cells, T lymphocytes, B lymphocytes and HLA-DR positive cells. There was no significant difference of the numerical density on the area of Langerhans cells between the cholesteatoma matrices and the normal ear canal skin. The numerical density on the area of T4 and the ratio of T4/T8 of cholesteatoma were higher than those of the normal ear canal skin. Through cell-to-cell interaction, Langerhans cells probably play a key role in skin-related disorders, including cholesteatoma.

Adolescent↗
PubMed1995

[The reverse-flow lateral sural cutaneous artery island flap: anatomical study].

The circulatory pattern of a skin flap was studied by microsurgical dissection, dye injection and angiography in 50 lower legs of fresh cadavers. The conclusions are as following: (1) The lateral sural cutaneors artery descends constantly and superficially accompanied by concomitant nerves. The upper post-lateral area of the lower leg in the best donor site of the flap. (2) The lateral sural cutaneous artery and the peroneal perforating artery form a anastomotic arcus around the lateral malleolus in 88.6% of the lower legs. The mean diameter of the anastomotic arcus is 0.63 +/- 0.19 mm. (3) The peroneal perforating vessel is 3.5 +/- 1.4 cm in length. Based on it the pedicle of the flap can be prolonged 6-8 cm on the main vessel of the lateral sural cutaneous artery. (4) Creation of the flap has no influence to the blood supply and function of the lower leg. (5) By anterograde transfer, the lateral sural island flap could be used to repair the defects around the knee and upper tibia. However, retrograde transfer of the flap has a higher clinical values in repiring the defects on the lower one third of lower leg and medial malleolus.

Adult↗
PubMed1995

[Rapid detection of Mycoplasma pneumoniae in clinical samples by the polymerase chain reaction technique].

The polymerase chain reaction (PCR) technique was used to detect Mycoplasma pneumoniae in clinical samples (bronchoalveolar lavage fluids and throat swabs). A specific DNA sequence for M. pneumoniae was selected from a genomic library. The amplification target region was partial DNA sequence of the 500- bp fragment. The oligonucleotide sequence of two primers (MP5-1 and MP5-2) were complementary with the oligonucleotide sequence in two ends of the amplification target region. PCR with purified DNA fragment as templates yielded an expected 144-bp fragment from M. pneumoniae but not from any of the other Mycoplasma spp. assayed. With this method, the 144-bp product specific for M. pneumoniae could be obtained from a minimum of 10 pg of M. pneumoniae DNA. Subsequently this PCR technique was used for the detection of M. pneumoniae in bronchoalveolar lavage fluids or in throat swab samples. Thirty of 140 samples from the patients with non-bacterial pneumonia gave positive results in the test. Twenty-one indirect hemoagglutination test-negative clinical samples from the same patients of 140 cases gave positive results in the same PCR test. When the amplified products were hybridized with a complementary probe (MP5-4 oligonucleotide probe), thirty PCR-positive samples all gave positive hybridization signals. It suggests that PCR method can be used for the direct detection of M. pneumoniae in clinical samples.

Base Sequence↗
PubMed1995

Interaction between intercalation type anticancer drugs and DNA studied by ultraviolet resonance Raman spectroscopy.

The interaction of typical intercalation type anticancer drugs, adriamycin (ADM) and aclacinomycin (ACM), with calf thymus DNA was studied first with ultraviolet resonance Raman spectroscopy (UVRRS). The results demonstrate that the important information such as intercalation sites of drugs, the electronic interaction and the hydrogen bonds between drugs and DNA can be obtained by UVRRS. The method can also show the influence of drugs on DNA conformation and hydrogen bonds between bases of DNA.

Aclarubicin↗
PubMed1995

[Antitussive, expectorant and anti-asthmatic effects of Cynanchum glaucescens (Decne.) Hand. -Mazz].

The water, ethanol and ether extracts from Cynanchum glaucescems administrated orally showed significant antitussive effect in ammonia-induced cough model in mice. The water and ethanol extracts had obvious expectorant effect. The filtered solution of water decoction injected intraperitoneally could effectively prevent guinea pigs from asthma induced by acetulcholine and histamine mixture, and also inhibit the ear inflammation in mice caused by croton oil. All these effects showed close dose-effect relationship.

Animals↗