Biomedical subjects

X Zhao

Publications and source records attributed to X Zhao.

At least 523 records · Page 29Linked to original sources

PubMed1996

Evaluation of a simplified method for site-specific determination of mutans streptococci levels.

To determine the oral mutants streptococcal "load" of an individual, saliva samples reflecting the number of colonized tooth surfaces, are often applied. Sometimes a plaque sample from a specific site would be an advantage, for example in connection with local antimicrobial treatments. The aim of the present paper was to evaluate a chairside method for determination of mutans streptococci interproximally. One hundred subjects participated. Four approximal tooth surfaces of each individual were sampled using toothpicks. The toothpicks were then let to contaminate a pad on a specially designed plastic strip and, for comparison, a MSB-agar plate. The strips were incubated in the standard "Strip mutans" broth. The yield of colony forming units on the strip surface corresponded significantly with that on agar plates. Being a simple chair-side method for the evaluation of the site-specific load of mutans streptococci, it is suggested that the method will be used in various investigations to clarify its potential in different clinical situations.

Adult↗

PubMed1996

[Ribozyme targeted the point-mutation of activated oncogene inhibits its expression in vivo].

We demonstrated previously that the hammerhead ribozyme designed by us against the activated oncogene T24-ras cleaved the target mRNA specifically and efficiently in vitro. To study its properties in vivo, we cloned the DNA fragment encoding the ribozyme into the eukaryotic expression vector pSMG and transfected it into the T24-ras gene transformed NIH3T3 cell lines. The intracellular cleavage of T24-ras mRNA was evaluated on either the cytological level or the molecular level. The malignant cells expressing ribozyme were partially reversed in morphology as evidenced by slower growth speed, partial recovery of contact-inhibition, reduced frequency of colony forming in soft agar and close-to-normal behaviour in agglutination teat. The primer extension experiment verified that the ribozyme had efficiently cleaved the transcripts of T24-ras gene at the target site in vivo.

3T3 Cells↗

PubMed1996

Amplification, cloning, and sequence comparison of the growth hormone gene for carp (Cyprinus carpio) by the polymerase chain reaction.

Total RNA was isolated from carp pituitary gland. The first strand cDNA was synthesized using oligo(dT) 12-18 as a primer, the total RNA as a template, and AMV reverse transcriptase. Next the polymerase chain reaction (PCR) was performed using the first strand cDNA as a template, the synthetic 29 oligonucleotides as primer and Taq DNA polymerase (94 degrees C, 60 s; 55 degrees C, 30 s; 72 degrees C, 50 s; 35 cycles). After PCR amplification, the products were cloned into an E. coli expression vector (PBluescript II KS+/-). The result of the sequence analysis and the restriction map shows that an open reading frame of the carp growth hormone gene contains 630 base pairs which code for a polypeptide of 210 amino acids including 22 amino acids of the signal peptide and 188 amino acids of the nature growth hormone. Nucleotide sequence and amino acid sequence of our carp growth hormone gene are the same as Koren's carp GH cDNA in the coded region. Compared with Chao's carp GH cDNA, the homology of nucleotide sequence and amino acid sequence for our carp growth hormone gene is 95.6% and 96.7%, respectively, in the coded region.

Amino Acid Sequence↗

PubMed1996

Immunohistochemical detection and significance of hepatitis C virus antigen.

OBJECTIVE: To study the expression and clinical significance of hepatitis C virus (HCV) antigens in liver tissues of patients with liver disease. PATIENTS AND METHODS: Hepatitis C virus antigen in paraffin-embedded liver tissues was detected by immunohistochemical method using polyclonal anti-HCV and monoclonal anti-HCV NS3. RESULTS: Among the 252 liver tissues, 25 (9.92%) were positive for HCAg (detected with polyclonal anti-HCV), and 19 (7.74%) were positive for HCV-NS3 (detected with monoclonal anti-HCV-NS3). All of the 19 HCV NS3 positive tissues were also positive for HCAg. Their distribution in liver tissue was similar, locating in the cytoplasm of liver cells. In most tissues, the positive cells scattered in liver lobulus, without obvious approach to the necrosis and infiltration aggregation; while a few samples showed positive cells clustered or diffused, with some necrosis or/and inflammatory infiltration. Of the 252 sera samples, 71 had HCV antibody or/and HCV RNA, showing a good correlation between HCV antigen in liver tissues and HCV marker in sera, but the detection rate of HCV antigen in liver tissues was much lower than that of HCV markers in sera. Two cases had HCV antigen in their liver with no HCV markers in their sera. CONCLUSION: Stored paraffin-embedded liver tissue can be used in the study of the immunopathology of HCV: no definite relationship between the expression of HCV antigens and liver damage has been found. Further study of the pathogenesis of HCV is needed.

Hepacivirus↗

PubMed1996

A study of time window for oxidative stress associated with myocardial ischemia and reperfusion.

OBJECTIVE: To investigate the time window for oxidative stress occurred in myocardial tissue and associated with reperfusion. METHODS: Thirty nine conscious rabbits were subjected to 0.5 hours (h) of myocardial ischemia and reperfusion for 0 h, 6 h, 24 h and 72 h, respectively, and nine rabbits served as controls. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and myeloperoxidase (MPO), and contents of GSH and malondyaldehyde (MDA) were measured in myocardial tissues taken from ischemic non-necrotic area (INNA), ischemic necrotic area (INA) and non-ischemic area (NIA), respectively. RESULTS: The antioxidant status of INNA was weakened at 6th h, 24th h, and 48th h of reperfusion. Activities of Mn-SOD and Cu-Zu-SOD returned to normal value at 72nd h of reperfusion, but GSH-px activity and GSH content remained in lower value. MDA content had a marked increase at 6th h, 24th h, 48th/h and 72nd h of reperfusion. MPO activity had a progressive increase after reperfusion, with its peak value at 48th h, and PMN accumulation occurred mostly in necrotic zone and its outer board zone. A mild oxidative stress also occurred in non-ischemic tissue, but without obvious neutrophils infiltration. CONCLUSIONS: The time window for oxidative stress associated with myocardial ischemia and reperfusion lasts for at least 72 h, and PMN infiltration is one of the most important factors of delayed myocardial reperfusion injury.

Animals↗

PubMed1996

[In situ observation of the relationship between apoptosis and proliferation in large bowel carcinoma and its precancerous lesion].

OBJECTIVE: To investigate action of apoptosis in tumorigenesis by observation of the relationship between apoptosis and proliferation. METHOD: Using terminal deoxynucleotidyl transferase-mediated dUTP niok end labelling (TUNEL) technique, PCNA immunohistochemical staining, and HE staining, we observed the density and distribution of apoptotic cells, proliferating cells and mitotic cells in situ in 15 normal mucosa, 32 villous adenoma and 33 papilloid adenocarcinoma of large bowel. RESULTS: The zone of apoptotic cells located in superficies and zone of proliferating cells in base in normal mucosa. These characteristics of distribution were lost in villous adenomas and papilloid adenocarcinomas of large bowel. The density of apoptotic cells in villous adenomas was significantly higher than that in normal mucosa and carcinomas. The density of apoptotic cells lowered and the density of proliferating cells rose in villous adenomas. Comparison of villous adenoma with papilloid adenocarcinoma, showed that apoptotic cells decreased and proliferating cells increased significantly. CONCLUSIONS: Through selectivity, the cells have highly proliferative ability prodominanted, resulting in malignant transformation. This phenomenon was named as a selective proliferation of cells.

Adenocarcinoma, Papillary↗

PubMed1996

[A pathologic study of delayed myocardial reperfusion injury].

This study was designed to investigate whether a new irreversible injury to the myocardium can occur 6 hours after reperfusion following ischemia. Conscious rabbits were subjected to myocardial ischemia for 30 minutes, followed by reperfusion. Horseradish peroxidase (HPR) tracing with TTC staining and histological quantification were used to study the histopathological changes in myocardial tissues. Necrotic myocardium at 6 hours after reperfusion gave positive HRP results and viable myocardium at 24 hours after reperfusion gave positive TTC results. Some myocardial tissue between the above two regions were found to be HRP negative as well as TTC negative, indicating that myocardial tissue death occurred between 6 to 24 hours after reperfusion. The myocardial infarct size at 24, 48, and 72 hours after reperfusion were 7.0%, 5.1% and 3.2% larger than that 6, 24 and 48 hours respectively. Therefore, new irreversible myocardial injury in the rabbit can still occur after 6 hours of reperfusion following myocardial ischemia for 30 minutes and cumulative myocardial injury from 6 to 72 hours after reperfusion can result in a marked extension of the size of myocardial infarct.

Animals↗

PubMed1996

[Expression and significance of bcl-2 oncogene protein in follicular lymphoma and lymphoid follicular hyperplasia].

In order to distinguish follicular lymphoma (FL) from follicular hyperplasia (FH), immunohistochemical staining method was used to detect the expression of bcl-2 oncogene protein in 22 cases of FL and 14 cases of FH. The results showed that bcl-2 was positive in 19 and negative in 3 of the 22 FLs, but negative in 12 and weakly positive in 2 of the FHs. These findings suggest that bcl-2 can play an important role in the differential diagnosis of FL and FH.

Adult↗

PubMed1996

[The effects of small dosage inactivated BCG vaccine on cellular immune function of pulmonary chronic obstructive disease patients with deficiency of lung-qi].

UNLABELLED: To investigate the effects of the small dosage inactivated BCG vaccine on the cellular immune function of the patients suffered from pulmonary chronic obstructive disease with deficiency of the Lung-Qi, the authors observed the patients' immune function before and after BCG treatment for half a year. RESULTS: The peripheral blood T lymphocytes subsefs (CD3, CD4, CD8, CD4/CD8) and the conversion ratio of lymphocyte of the patients both were significantly lower than those of the healthy people (P < 0.01). But after the treatment of the small dosage inactivated BCG vaccine for half a year, these parameters of the patients were improved (P < 0.01 or P < 0.05). It indicated that the small dosage inactivated BCG vaccine could improve the damaged cellular immune function.

Aged↗

PubMed1996

[Electron microscopic observation of hepato-cellular carcinoma in 15 cases--an ultrastructural comparison with human embryonic liver].

An ultrastructural comparison between 15 cases of hepatocellular carcinoma (HCC) and 5 cases of human embryonic liver (HEL) was performed. There were similarities. Both of them are polygonal in cell shape with a central nucleus and are abundant in RER and mitochondria; both have laminating form of RER and formation of bile capillary and perisinusoid space. These are important evidences for diagnosis of a tumor originating from hepatic cells. On the other hand, obvious differences were present between HCC and HEL. Cancer cells possess certain characteristics; they are pleomorphic and heterogeneitic; the differentiation of their ultrastructural components is not synchronic, and they are invasive in growth. These enable us to suspect the malignancy of a tumor. In addition, single death cancer cells with pyknotic nucleus were seen in HCC; some of them were phagocytozed by adjacent cells. We conside these are apoptosis even no formation of apoptoic bodies was found. In the majority of HCC cases, lymphocyte-mediated cancer cell lyses by both T-lymphocytes and large granular lymphocytes (nature killer cell) were found.

Adult↗

PubMed1996

[In situ hybridization to detect the mRNA for insulin-like growth factor-I and II in the prostate].

In order to well understand the expression of mRNA for insulin-like growth factor I and II in normal and hyperplastic prostate, in situ hybridization were used to detect them in a total of 35 cases of prostate. Both the normal and the hyperplastic prostate expressed the mRNA for IGF-I/II. The mRNA for IGF-I was mainly expressed by the epithelial cells and the IGF-II was mainly expressed by the stromal cells. The hyperplastic tissues expressed higher levels of the mRNA for IGF-I and IGF-II. The results suggested that the IGF might play an important role in the regulation of prostate growth and the pathogenesis of benign prostatic hyperplasia.

Adolescent↗

PubMed1996

[Estradiol receptors expression in nasal polyps and its significance].

Nasal polyps are generally considered as a result of extreme nasal mucosal edema induced by long-term recurrent inflammation of the respiratory mucosa. The estradiol (E2) has been demonstrated to play a facilitating role in nasal inflammation. To evaluate the effect of estradiol on the pathogenesis of nasal polyps, the expression of E2 receptors in paraffin section from patients with nasal polyps (84 cases), chronic hypertrophic rhinitis (6 cases) and healthy control subjects were investigated by means of immunohistochemistry for E2 receptors and toluidine blue staining for mast cells. It was shown that there was high expression of E2 receptors in 61 out of 84 cases (male 40, female 44) of nasal polyps and the expression distributed equally among both sexes. Low expression of E2 receptors presents in 2 out of 6 cases of chronic rhinitis and 1 out of 4 healthy subjects. Noteworthily, the E2 receptor expressing cells are similar with the mast cells in shape and distribution. The authors speculate that they may be identical cells. E2 receptor expression in nasal polyps suggests that estradiol plays certain role in the development of nasal polyps.

Adult↗

PubMed1996

[A study of tracheal defect repair in rabbits with collagen-hydroxylapatite].

An artificial material composed of collagen-Hydroxylapatite (C-HA) was used to repair the tracheal defect of rabbits. There was no reaction, no absorption and no particle detachment after the C-HA was implanted. We also found that the tracheal mucosa could grow over the surface of C-HA. The result suggested that the C-HA can be used as a material for repairing the tracheal defect of the tracheostenosis.

Animals↗

PubMed1996

[Studies on sapogenins of Aesculus wilsonii Rehd].

Three sapogenins were isolated from the hydrolysate of the saponin mixture extracted from the seeds of Aesculus wilsonii. They were identified as 21-angeloyl-protoaescigenin., aescigenin and protoaescigenin by physicochemical propertise and spectroscopic analysis.

Drugs, Chinese Herbal↗

PubMed1995

Roles of a membrane-localized beta subunit in the formation and targeting of functional L-type Ca2+ channels.

We report several unexpected findings that provide novel insights into the properties and interactions of the alpha 1 and beta subunits of dihydropyridine-sensitive L-type channels. First, the beta 2a subunit was expressed as multiple species of 68-72 kDa; the 70-72-kDa species arose from post-translational modification. Second, cell fractionation and immunocytochemical studies indicated that the hydrophilic beta 2a subunit, when expressed alone, was membrane-localized. Third, the beta 2a subunit increased the membrane localization of the alpha 1 subunit and the number of cells expressing L-type Ca2+ currents, without affecting the total amount of the expressed alpha 1C subunit. Expression of maximal currents in alpha 1C/beta 2a cotransfected cells paralleled the time course of expression of the beta subunit. Taken together, these results suggest that the beta subunit plays multiple roles in the formation, stabilization, targeting, and modulation of L-type channels.

Amino Acid Sequence↗

PubMed1995

Colocalization of the homophilic binding site and the neuritogenic activity of the cell adhesion molecule L1 to its second Ig-like domain.

The cell adhesion molecule L1 has been implicated in mediating cell-cell adhesion and in promoting neurite outgrowth. The extracellular region of L1 contains six immunoglobulin (Ig)-like domains in the amino-terminal region, followed by five fibronectin type III-like repeats. L1 is capable of undergoing homophilic binding as well as heterophilic interactions. To map the homophilic binding domain in L1, three glutathione S-transferase (GST) fusion proteins (GST-Ig1-2-3, GST-Ig4-5-6, and GST-Fn) were prepared and coupled to Covaspheres and their homophilic binding activity was determined using the Covasphere-to-substratum binding assay. Only GST-Ig1-2-3 was capable of homophilic binding. Next, His-tagged recombinant Ig-domain proteins (His-Ig1-2, His-Ig1, and His-Ig2) were expressed and subjected to similar assays. Only His-Ig1-2 and His-Ig2 were capable of homophilic interactions. Binding of His-Ig2-conjugated Covaspheres to substrate-coated His-Ig2 was inhibited by anti-Ig1-2-3 Fab and soluble His-Ig2. These results indicate that the L1 homophilic binding site resides within Ig2. To examine effects of these L1 recombinant proteins on neurite outgrowth, neural retinal cells were cultured on different substrate-coated fusion proteins. Both GST-Ig1-2-3 and His-Ig2 were potent inducers of neurite extension. These results thus indicate that the L1 Ig-like domain 2 alone is sufficient to mediate L1-L1 interaction and promote neurite outgrowth from retinal cells.

Amino Acid Sequence↗

PubMed1995

Brief potassium depolarization decreases levels of neurofilament proteins in CNS culture.

Little is known about the effects of brief potassium depolarization that occurs concurrently with transient ischemia, epilepsy and head trauma. To investigate the effect of short-term depolarization on light (NF-L), middle (NF-M), and heavy (NF-H) neurofilament proteins and determine the role played by calcium in that effect, mixed septo-hippocampal cultures were exposed to 60 mM K+ for 6 min, in the presence of 0 to 11.8 mM Ca2+. Twenty-four hours later, neurofilament immunoreactivity in Western blots of depolarized cultures was decreased to 60% or less of control levels. Decreases were Ca2+-dependent, not due to cell loss, and affected both phosphorylated and nonphosphorylated proteins. The phosphorylation state of NF-M and NF-H influenced the degree of loss observed. Changes in the pattern of immunolabelling of neuritic processes were also associated with depolarization. Thus, brief potassium depolarization may contribute to cytoskeletal disruption following brain injury.

Animals↗

PubMed1995

Time course of neurofilament protein loss following depolarization-induced injury in CNS culture.

In septo-hippocampal cell cultures, brief potassium depolarization produces calcium-dependent decreases in neurofilament proteins and loss of fine neuritic processes within 24 h. It is not known whether neurons later exhibit delayed degeneration and die, live with enduring neurofilament loss, or restore neurofilament protein levels. Therefore, we exposed septohippocampal cultures to 6 min potassium depolarization (60 mM) with 2.8-11.8 mM extracellular Ca2+ and evaluated immunoreactivity for low, medium and heavy neurofilament proteins, neuronal number, and neuronal morphology for 10 days. Neuronal number remained unchanged; neurofilament protein levels recovered to between 31% and 99% of control levels, and fine neuritic processes reappeared.

Animals↗