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Biomedical subjects

M Zeng

Publications and source records attributed to M Zeng.

65 records · Page 4Linked to original sources
PubMed1997

[Correlation between hepatic fat, lipid peroxidation and hepatic fibrosis in rats chronically fed with ethanol and/or high fat diet].

UNLABELLED: To explore the correlation between hepatic fat and fibrosis and the possible causative mechanism. 40 Wistar rats were randomized into 4 groups i.e. low fat diet (group I), high fat diet (group II), low fat diet plus ethanol (group III), high fat diet plus ethanol (group IV). Rats were sacrificed at 3 and 6 months after experiment. Triglyceride (TG), malonaldehyde (MDA) and hydroproline (Hyp) content in the liver were measured with biochemical analysis. The degree of steatosis and fibrosis and the amount of alpha-smooth muscle actin (alpha-SMA) positive cells in the liver were determined by HE, van Giesson and immunohistochemical ABC stain, respectively. RESULTS: Steatosis was observed in most of the group II, III, IV animals including those sacrificed at 3 months after experiment, but increased amount of alpha-SMA positive cells and hepatic fibrosis was only shown in group III and IV. As compared with group I, hepatic TG content was increased significantly in the group II, III, IV animals, and hepatic MDA and Hyp content were increased significantly in the group III, IV animals. Moreover, changes of these biochemical and histological indexes in group IV were the most outstanding. There was no significant correlation between hepatic TG content and amount of alpha-SMA positive cells in group II, III, IV and no correlation between hepatic TG and Hyp content in group II, IV, and there was significant correlation between hepatic MDA content and Hyp content and the number of alpha-SMA positive cells in group III, IV. CONCLUSIONS: There is no direct relationship between steatosis and initiation of lipocyte activation and resulting fibrogenesis, but hepatic fat per se may promote the initiation and development of hepatic fibrosis induced by the injurious factors of increasing lipid peroxidation.

Animals↗
PubMed1996

Ionizing radiation greatly improves gene transfer efficiency in mammalian cells.

The vast majority of clinical protocols involving gene therapy today rely on viral vectors for gene transduction. The primary reason that plasmid vectors have not been widely used for gene therapy trials is their relatively low rate of stable gene transfer. We show here that ionizing radiation can improve plasmid transfection efficiency in both normal and neoplastic human and mouse cells. As high as 1,400-fold improvement in transfection efficiency can be seen in primary human fibroblasts treated with 9 Gy. Radiation improves transfection efficiency in a dose-dependent manner of only linearized plasmid DNA in transformed or immortalized cells, but of both linearized and supercoiled plasmid in normal human fibroblasts. The gene transfer dose-response curves are linear for neoplastic cell lines and exponential for primary cell lines. This suggests that radiation can improve gene integration by at least two mechanisms, one that may require free DNA ends and one that does not. The 2-hr delay described here, from the time of irradiation to the beginning of enhanced gene integration, suggests an inducible process that becomes active after the bulk of the radiation damage has been repaired. Our data further suggest that radiation may be useful to target human gene therapy using plasmid vectors.

Animals↗
PubMed1996

Cloning strategies using a third irrelevant enzyme site (TIES) to overcome certain cloning problems.

We describe a cloning strategy, third irrelevant enzyme site (TIES), based on three-component assembly ligation reactions to overcome seven types of problematical cloning reactions. Implementation of the TIES strategy has made it possible to obtain the desired recombinant where the corresponding approach using conventional recombinant DNA methodologies and two-component ligations failed to give the desired product.

Binding Sites↗
PubMed1996

[Expression of myelin basic protein gene in the developing human brain].

The expression of myelin basic protein (MBP) gene in the developing human brain was studied by using Northern dot blot and in situ hybridization with 32P- and biotin-labeled rat MBP cDNA and Diglabeled human MBP cRNA probes so as to explore the relation of temporal and spatial expression of human MBP gene to myelinogenesis and myelination. The results of dot blot analysis showed that the expression of MBP mRNA was near 2.0 A590/microgram of RNA in the fetal brain at 16 weeks of conceptional age, and it increased progressively with development to have 9-fold increment (18 A590/microgram of RNA) in the adult brain. The insitu hybridization was performed with the sections of fetal spinal cord and medulla oblongata at 8-25 weeks of conceptional age, and of pons, midbrain, thalamus, cerebellum and cerebrum at 20, 22 and 25 weeks. The results indicated that the expression of MBP mRNA was found as early as 8-9 weeks and localized within the perinuclear cytoplasm of the scattered cells in the ventral horn of spinal cord and near the basis of the fourth ventricle of medulla oblongata. Whether the above-mentioned labeled cells are neurons or precursors of glial cell remains to be identified because they are larger in size and have more abundant cytoplasm than oligodendrocytes. The labeling of MBP mRNA abruptly increased and spread with the processes of oligodendrocytes to form a network in spinal cord and medulla at 20 weeks; meanwhile, labeling was obvious in pons and scattering in the other brain regions examined.

Adult↗
PubMed1995

Isolation and characterization of Marek's disease virus (MDV) cDNAs mapping to the BamHI-I2, BamHI-Q2, and BamHI-L fragments of the MDV genome from lymphoblastoid cells transformed and persistently infected with MDV.

We have isolated and sequenced two cDNAs of sizes 2674 and 677 bp from a cDNA library derived from MKT-1, a lymphoblastoid cell line transformed and latently infected with Marek's disease virus (MDV) using probes corresponding to the right-hand end of the BamHI-I2 fragment of the MDV genome. The larger cDNA clone represents an abundant transcript, which extends from the right-hand end of BamHI-I2 to the adjacent BamHI-Q2 and BamHI-L fragments of the MDV genome and contains the Meq (MDV Eco-Q) open reading frame. The smaller cDNA clone represents a spliced transcript containing the putative DNA binding domain of Meq as well as sequences in the BamHI-L region. We prepared a polyclonal antibody against part of the protein sequence of Meq and detected a 44-kDa protein in MKT-1 cells and in cells lytically infected with MDV. In addition, riboprobes corresponding to sequences specific to each cDNA as well as shared sequences between cDNAs detected a number of transcripts in cells either lytically or latently infected with MDV. Our results indicate that the Meq transcriptional unit extends to the BamHI-L fragment and that the transcripts mapping to the right-hand end of the BamHI-I2 and adjacent BamHI-Q2 and BamHI-L fragments are not preferentially expressed during latency.

Amino Acid Sequence↗
PubMed1995

[Analyses of the prevalences for neural tube defects and cleft lip and palate in China from 1988 to 1991].

This paper reports the monitoring results of two main categories of birth defects-neural tube defects (NTD) and cleft of lip and palate (CLP) in China during the period of continuous monitoring (1988-1991). The method of hospital-based monitoring was adopted for data collection. From Jan. 1988 to Dec. 1991, a total of 2,750,588 births were monitored, and 28,168 cases of congenital malformations were identified. The prevalence of total birth defects was 102.4 per 10,000. 6885 cases of NTD were identified during this period, the prevalence of NTD being 25.0 per 10,000. The prevalence of NTD varied geographically; it declined gradually from the north to the south of China with the highest rate of NTD in the Taihang Mountain Regions. A total of 4548 cases of CLP were identified, and the provincial prevalence of CLP varied from 11.2 to 25.7 per 10000 with a mean of 16.5 per 10000. The prevalence of NTDs varied seasonally with the peak in winter (January). The sex ratio of NTD was 0.59, the prevalences in female births (32.1 per 10,000) being higher than that in male births (17.4 per 10,000) (P < 0.01). The sex ratio of CLP was 1.33. A significant difference was noted between the sex ratio of cleft palate (0.80) and that of the total cleft lip (1.46) (P < 0.01). The prevalence of NTD in rural areas (44.3 per 10,000) was 3 times as high as that in urban areas (14.4 per 10,000), but no difference in occurrence of CLP was observed between the urban and rural areas (P > 0.05).

China↗
PubMed1995

[Ultrastructural study of human yolk sac].

Twenty cases of human yolk sac of different gestation weeks observed by electron microscopy. The wall of yolk sac consisted of endoderm, mesenchyme and mesothelium. Nuclei of the endodermal cell were large and nucleoli were remarkable. The surface of endodermal cell presented a number of microvilli. There were Golgi complex, rough endoplasmic reticulum, glycogen and mitochondria in the cytoplasm of the endodermal cell. The fibroblast-like cell, macrophage-like cell. erythroblast in various mature degree, collagen filament and capillaries were found in the mesenchyme. The mesothelial cell had long, slender microvilli, which were mostly branched. Pinocytotic vesicles in the apical cytoplasm beneath the mesothelial cell membrane were frequent. The differently sized endodermal tubules with well-defined lumen and microvilli were recognized by electron microscopy. Masses of endodermal cells frequently invaginated in the mesenchymal layer, and they often reached the mesothelial layer. These structures of yolk sac were the foundation of finishing synthesis, secretion, translation and hematopoiesis during early organogenesis.

Female↗
PubMed1993

[Comparison of irradiated porcine skin with exposure or occlusive method in the care of second degree burn wounds].

This article compared irradiated porcine skin with exposure and occlusive method in the care of second degree burn wounds. In 30 patients in whom irradiated porcine skin (IPS) was used, no wound infection occurred. The rate of wound infection, in patients on whom herb medicine and exposure method were used, was 19% (7/37), and that of occlusive dressing plus drug group was 22% (2/9). The rate of wound infection of IPS was significantly lower than the other two groups (P < 0.05). The time of wound healing in IPS group was 13.5 + 5.03 days; it was significantly shorter than the other two groups.

Adolescent↗
PubMed1990

[Relation of serum growth hormone and estradiol levels and osteoporosis in postmenopausal women].

Serum GH, E2, FSH, LH levels, bone mass, serum alkaline phosphatase (AKP), calcium levels and urinary calcium/creatine ratio in 42 postmenopausal women were compared with those in 30 women of fertile age. In thirteen out of the postmenopausal women we also observed these parameters before and after treatment with diethylstilbestrol (DES). The postmenopausal women had significantly reduced serum GH (P less than 0.01) and E2 levels (P less than 0.001) and increased serum FSH(P less than 0.001), LH levels (P less than 0.001), and had lower bone mass (P less than 0.01). They also had increased serum AKP levels (P less than 0.05) and urinary calcium/creatine ratio(P less than 0.01). There were positive correlations between serum E2 and GH levels, between postmenopausal bone loss and serum E2, GH decline. The postmenopausal bone loss began early as menopause commenced. After treatment with DES in 13 postmenopausal women, we observed that GH significantly increased (P less than 0.01) and FSH, LH decreased (P less than 0.001), AKP decreased by 27.58% and urinary calcium/creatine ratio decreased by 43.94% (compared with that before treatment). Our results indicate that bone turnover increased after menopause and resorption exceeded formation. There is bone loss in early postmenopause. The postmenopausal bone loss is related to serum GH, E2 levels. Estrogen replacement therapy is necessary in postmenopausal women and it should be given as early as possible. After treatment with DES, increased serum GH levels, decreased AKP values (27.58%) and urinary calcium/creatine ratio (43.94%) suggest that estrogen may play a definite role in bone metabolism through increased GH.

Aged↗