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Min Xu

Publications and source records attributed to Min Xu.

140 records · Page 8Linked to original sources
PubMed2002

Helix-loop-helix proteins regulate pre-TCR and TCR signaling through modulation of Rel/NF-kappaB activities.

E2A and HEB are basic helix-loop-helix transcription factors essential for T cell development. Complete inhibition of their activities through transgenic overexpression of their inhibitors Id1 and Tal1 leads to a dramatic loss of thymocytes. Here, we suggest that bHLH proteins play important roles in establishing thresholds for pre-TCR and TCR signaling. Inhibition of their function allows double-negative cells to differentiate without a functional pre-TCR, while anti-CD3 stimulation downregulates bHLH activities. We also find that the transcription factor NF-kappaB becomes activated in transgenic thymocytes. Further activation of NF-kappaB exacerbates the loss of thymocytes, whereas inhibition of NF-kappaB leads to the rescue of double-positive thymocytes. Therefore, we propose that E2A and HEB negatively regulate pre-TCR and TCR signaling and their removal causes hyperactivation and apoptosis of thymocytes.

Animals↗
PubMed2002

Growth hormone downregulated the excessive apoptosis of ileal intestinal epithelial cells in rats during the early course of acute necrotizing pancreatitis.

INTRODUCTION: Growth hormone (GH) has beneficial effects in protecting the intestinal barrier integrity of rats with acute necrotizing pancreatitis (ANP), and the balance between apoptosis and proliferation of intestinal epithelium is one of the key factors in maintenance of the intestinal barrier homeostasis. AIM: To evaluate further the effect of GH on cell apoptosis of intestinal epithelium in rats with ANP. METHODOLOGY: Seventy-two rats were randomly divided into 3 groups: sham operation (SO) group (n = 24); ANP group (n = 24); and ANP with GH treatment group (n = 24). ANP in rats was established by injection of 5% sodium taurocholate into the biliopancreatic duct, and laparotomized animals without induction of ANP (sham operation) served as controls. The rats in the GH treatment group received human recombinant GH (0.75 U/kg body weight) subcutaneously once, immediately after operation. The segment of ileum was removed and the detached epithelial cells of ileum were harvested at 3 hours, 6 hours, 12 hours, and 24 hours after operation. Apoptosis of intestinal epithelium was studied by DNA gel electrophoresis, fluorescein isothiocyanate (FITC)-labeled annexin V and propidium iodide (PI) staining under flow cytometry, and the terminal deoxynucleotidyl transferase-mediated d-UTP-biotin nick end labeling (TUNEL) histochemical method. RESULTS: All specimens harvested at different time points from rats with ANP showed a marked DNA ladder pattern after agarose gel electrophoresis, in comparison with those in the SO group, indicating DNA fragmentation appeared at the early stage in the ANP group. However, a DNA ladder pattern was seen only at 3 hours after operation in the GH-treated rats. The apoptotic percentage assayed by flow cytometry with use of an annexin V kit at 6 hours in the ANP group was significantly higher than in the control group (80% +/- 9% versus 28% +/- 6%; p < 0.01) and was decreased markedly in the GH treatment group (27% +/- 15% versus 80% +/- 9%, p < 0.01). The apoptotic index, studied by the TUNEL method, was obviously higher in the ANP group than in the control group (3 hours: 18 +/- 4 versus 6 +/- 2; 6 hours: 20 +/- 3 versus 8 +/- 2; 12 hours: 15 +/- 2 versus 11 +/- 1; 24 hours: 14 +/- 2 versus 5 +/- 1; p < 0.01), whereas the apoptotic index in the GH treatment group decreased at 3 hours and 6 hours (10 +/- 2 versus 18 +/- 4; 10 +/- 2 versus 20 +/- 3; p < 0.01). The same results were achieved for the apoptotic index of villi tips in the three groups. CONCLUSION: Apoptosis is a principle model of intestinal epithelial cell death at the early stage of ANP, and GH may downregulate the apoptosis significantly. This action probably is involved in the mechanisms contributing to the protective effects of GH on intestinal barrier integrity in ANP.

Animals↗
PubMed2002

Improvement of AMPLICOR human immunodeficiency virus type 1 viral load test (version 1.5) by addition of a coprecipitant during the RNA isolation step.

The effect of the addition of a coprecipitant during the RNA isolation step on the analytical performance of the COBAS AMPLICOR human immunodeficiency virus type 1 (HIV-1) Monitor (version 1.5; Roche) viral load test was tested. Thirty-six specimens including patient samples, positive control samples, and negative control samples were processed in the presence and absence of the Pellet Paint coprecipitant. Specimens processed without the coprecipitant had lower RNA yields, as evidenced by a lower signal for the quantitation standard (QS). In addition, the results for all samples processed with the coprecipitant were acceptable on the basis of the optical density (OD) reading for the QS, whereas the result for one specimen processed without the coprecipitant was unacceptable on the basis of the OD reading for the QS, which required the assay to be repeated. Furthermore, the use of the coprecipitant improved the overall precision of the assay.

Chemical Precipitation↗
PubMed2002

The abnormal expression of retinoic acid receptor-beta, p 53 and Ki67 protein in normal, premalignant and malignant esophageal tissues.

AIM: Esophageal cancer remains a significant health problem worldwide. It is important to investigate alterations in expression of retinoic acid receptor-beta, p 53 and Ki67 proteins in esophageal carcinogenesis. METHODS: To find biomarkers for early identification of esophageal cancer, we analyzed the retinoic acid receptor-beta, p 53 protein and the proliferation marker Ki67 in surgical specimens of normal, mildly, and severely dysplastic and malignant esophageal tissues by in situ hybridization of RNA and immunohistochemistry. RESULTS: RAR-beta was expressed in 94.3%(33/35) of normal mucosae, 67.8%(19/28) of the mild, 58.1% (18/31) of the severe lesions and 53.2%(116/218) of tumor samples. RAR-beta mRNA was expressed in 62.7%(42/67), 55.1%(43/78) and 29.2%(7/24) of well, moderated and poorly differentiated SSCs. The p 53 and Ki67 proteins were 5.9%(2/34) of the normal mucosa. P53 and Ki67 stained positively in 10.7%(3/28) and 21.4% (6/28) of mild dysplasia, and 51.6%(16/31) and 58.1% (18/31) of severely dysplasia respectively. Samples from esophageal cancer showed no higher levers of p 53 and Ki67 expression than seen in severely dysplastic lesions. There was significant difference of RAR-beta p 53 and Ki67 expression between normal mucosa and dysplastic tissue or esophageal cancer. CONCLUSION: Loss of RAR-beta expression and accumulation of p 53 and Ki67 proteins may serve as biomarkers for early identification of esophageal cancer in the high-risk populations.

Biomarkers, Tumor↗
PubMed2002

[Identification of nonmuscle mysin heavy chain 9 gene mutation in a May-Hegglin anomaly family].

OBJECTIVE: To describe the clinical phenotype and identify the nonmuscle myosin heavy chain 9 (MYH9) gene mutation in the first May-Hegglin anomaly family in China. METHODS: The exons 25, 31 approximately 32 38 and 40 in the MYH9 gene of the proband and her affected father were amplified with polymerase chain reaction, and the PCR products were sequenced. After the specific point mutation in exon 38 was identified in these two cases, the corresponding region of the MYH9 gene was amplified and nuclear acid sequence analysis was conducted among 30 healthy persons, one patient with idiopathic thrombocytopenic purpura and one patient with thrombotic thrombocytopenic purpura. The CpoI restriction endonuclease map from the PCR products of exon 38 of MYH9 gene was analysed among the proband, her father and other family members, 30 normal controls, 1 ITP patient, and one TTP patient. RESULTS: The proband and her affected father manifested a typical triad of thrombocytopenia, giant platelets, and inclusion bodies in leukocytes. The patient showed mild hemorrhagic tendency since infancy, while the platelet aggregation function was normal. A 5521G --> A mutation (GAG --> AAG) in the exon 38 of the MYH9 gene existed in the proband and her affected father, resulting in a characteristic change in CpoI restriction endonuclease map. CONCLUSION: The cases of May-Heggelin anomaly in China show typical triad of thrombocytopenia, giant platelets, and inclusion bodies in leukocytes too. Mutation of MYH9 gene exists in cases of May-Hegglin anomaly in China. The point mutation is located in exon 38 (G5521A) in this family.

Adolescent↗
PubMed2002

Sentinel lymph nodes lymphoscintigraphy and biopsy in breast cancer.

OBJECTIVES: To determine the clinical value of sentinel lymph node (SLN) detection by lympho- scintigraphy and gamma ray detecting probe (GDP) and to assess the value of hematoxylin and eosin (H&E) staining combined with immunohistochemistry (IHC) analys is for detecting micrometastasis in lymph nodes (LNs). METHODS: Forty-two patients with breast cancer were included in this study. (99)Tc(m)-dextran was injected peritumourally. Lymphoscintigraphy images were obtained in anterior and lateral views. SLNs were removed with the aid of GDP during surgery. A standard axillary lymph nodes (ALNs) dissection was performed. All lymph nodes were first analyzed by HE staining. When all of the SLNs in a patient were negative, the ALNs were subjected to additional HE staining combined with IHC analysis. RESULTS: SLNs were successfully detected and removed in 39 (92.9%) of the 42 patients. The sensitivity, specificity and accuracy of SLN biopsy were 92.9% (13 in 14), 100% (25 in 25) and 97.4% (38 in 39) respectively. Additional HE staining combined with IHC analysis of the ALNs detected micrometastasis in 3 SLNs (2 cases), but there were no positives in the non-sentinal lymph nodes (NSLNs). CONCLUSIONS: This study suggests that lymphoscintigraphy and GDP may be used to detect SLN. Additional HE staining combined with IHC analysis of the ALNs may help predict micrometastasis. Biopsy of SLN may be an accurate method for staging breast cancer.

Adult↗
PubMed2002

[Study on the relationship of balanced translocation t(1;12) with spermatogenesis].

OBJECTIVES: To investigate the relationship between chromosome balanced translocation t(1;12) (q24;q24) and spermatogenesis in infertile twin brothers. METHODS: For twin brothers, karotype were determined. The levels of testosterone, FSH and LH were detected. YRRM1, DAZ and DYS240 were analyzed. In younger brother a biopsy was taken from testis. RESULTS: Chromosome analysis for both twin brothers revealed a karotype of 46, XY, t(1;12) (q24;q24). Sperm count was less than 1.0 x 10(6)/ml. There was no deletion for YRRM1, DAZ and DYS240 gene on Y chromosome. Photomicrograph of seminiferous tubules showed the arrest of spermatogenesis. CONCLUSIONS: Chromosome balanced translocation t(1;12) (q24;q24) may be the cause of the spermatogenesis arrest in infertile twin brothers. Gene in the point of translocation may be related to spermatogenesis.

Adult↗
PubMed2002

[Significance of serological test of blood group in nonmyeloablative allogeneic peripheral blood stem cell transplantation of patients with acute leukemia].

The purpose of this study is to explore the clinical significance of RBC blood group serological test in nonmyeloablative allogeneic peripheral blood stem cell transplantation (NAPBSCT) of ABO group incompatibility in 4 patients with acute leukemia. ABO and MN blood group of donors and recipients were determined by hemagglutination test and Rh blood group by Diana Gel phenotype Rh card. The changes of blood group in recipients were observed and implant of donor cells was monitored by short tandem repeat-PCR method. The results showed that in 2 cases of 4 recipients the marrow cells appeared mixed chimera of donor and recipient cells, and blood group changed to donor type in 1 of the 2 cases on 100 days after transplantation. In another 2 cases, the marrow cells appeared mixed chimera without blood group chimera on 154 days after transplantation, and rejection of the transplant occurred in 1 of the 2 cases. The determination of hemagglutinin titer showed that the implant rate of donor cells was lower in the recipients with higher hemagglutinin titer and blood group chimera did not appear, conversely, the implant rate was higher in the recipients with lower titer and blood group chimera appeared early. It is concluded that examination of RBC blood group in NAPB SCT can indirectly reflect effectiveness of transplantation, contribute to decide the intensity of conditioning protocol and immunosuppressive therapy after transplantation, estimate prognosis and guide blood transfusion during transplantation.

Adult↗
PubMedDate not supplied

Expression of a novel RAD23B mRNA splice variant in the human testis.

A gene coding a novel human RAD23B protein named RAD23-like protein B, presumably involved in spermatogenesis, was identified and characterized using a complementary DNA (cDNA) microarray. In the human testis, its expression was 2.33 times higher than it was in the embryo testis, with a particularly high expression in ejaculated human spermatozoa. The full length of this gene is 1548 bp, and the putative protein is 338 amino acids long. This protein is homologous to RAD23B, which is one of two human homologs of Saccharomyces cerevisiae RAD23, and is involved in both nucleotide excision repair (NER) and ubiquitin (Ub)-dependent proteolysis. However, RAD23-like protein B lacks the Ub-like (UbL) domain that functions as a proteasome localization signal. Multiple-tissue expression profile of the messenger RNA (mRNA) that encodes the RAD23-like protein B also showed that it is highly expressed in the human testis and in ejaculated spermatozoa. Our present study indicates that this novel alternative splicing form of RAD23B is correlated with human spermatogenesis.

Amino Acid Sequence↗
PubMedDate not supplied

Novel development-related alternative splices in human testis identified by cDNA microarrays.

Alternative splicing of premessenger RNA is an important regulatory mechanism that increases the diversity of proteins transcribed from a single gene. This is particularly important in the testis because germ cell expansion and differentiation require many cellular changes and regulatory steps. To investigate novel development-related alternative splicings in the human testis, complementary DNA microarray studies were conducted with the use of probes from human fetal testes, adult testes, and human spermatozoa. Of a total of 386 Unigene clusters found to be related to the development of the testis, 67 clusters showed a total of 74 novel alternative spliceoforms. Developmental stage-dependent expression was also performed for a novel Unigene, NYD-SP20 (Hs.351068), which had 4 possible novel spliceoforms and another Unigene, CRISP2 (cysteine-rich secretory protein 2, Hs.2042), which had 3 possible novel spliceoforms. These results indicate that alternative splicing plays an important role in the complicated processes of testis development and spermatogenesis.

Adult↗
PubMedDate not supplied

gamma-Secretase: characterization and implication for Alzheimer disease therapy.

gamma-Secretase is a membrane-bound protease that cleaves within the transmembrane region of amyloid precursor protein to generate the C-termini of the Abeta peptides which are believed to play a central role in the neuropathology of Alzheimer's disease. An in vitro gamma-secretase assay using a recombinant substrate C100Flag has been developed to facilitate the characterization and identification of this enigmatic protease. Biochemical studies establish that gamma-secretase activity is catalyzed by a PS1-containing macromolecular complex. Moreover, the fact that the photoreactive active gamma-secretase inhibitor directed to the active site labels PS1 suggests that PS1 contains the active site of the protease. Presenilin/gamma-secretase as a potential target for AD therapy and its role in regulated intramembrane proteolysis are discussed.

Alzheimer Disease↗
PubMedDate not supplied

Cloning and characterization of a novel transcript variant of IQGAP2 in human testis.

Using cDNA microarray hybridization from a human testicular cDNA library, one gene exhibiting 6.4-fold difference at expression level between adult and embryo human testes was cloned and named tsIQGAP2 (testis specific IQ motif containing GTPase-activating protein 2). The full cDNA length of tsIQGAP2 is 3388 bp and contains a 3215 bp open reading frame, encoding a 122.85 kDa protein of 1071 amino acids. Sequence analysis showed that tsIQGAP2 harbors all the domains (one WW domain, three IQ motifs, and one RasGAP homology domain) in HsIQGAP2 (IQ motif containing GTPase-activating protein 2) except for the N-terminal calponin homology domain. Blasting human genome database localized tsIQGAP2 to human chromosome 5q13-14 and further investigation showed that it is a novel transcript variant of HsIQGAP2. The tissue distribution of tsIQGAP2 showed that it is a testis specific gene. The above results suggest the potential role of tsIQGAP2 during spermatogenesis and the mechanism by which tsIQGAP2 regulating spermatogenesis also has been proposed.

Alternative Splicing↗
PubMedDate not supplied

Mediastinal lymphangiohemangioma communicating with the left innominate vein.

The CT manifestation of lymphangiohemangioma in a 17-year-old boy is reported. A mass composed of the central malformed, dilated venous channels and peripheral unenhanced soft tissue was revealed in the anterior mediastinum. The venous feeding enhancement of the mass is very characteristic. The diagnosis of lymphangiohemangioma was made by pathologic study of the surgical specimen.

Adolescent↗