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Biomedical subjects

L Hao

Publications and source records attributed to L Hao.

At least 37 records · Page 2Linked to original sources
PubMed2000

Detection of transfusion transmitted virus in hepatic and extra hepatic tissues using in situ hybridization.

OBJECTIVE: To investigate the location, distribution and significance of transfusion transmitted virus (TTV) in the liver and extra hepatic tissues. METHODS: A 123 bp fragment of TTV DNA within ORF(2) was amplified by PCR reaction and cloned into PCR2.1 vector. DNA sequencing revealed that the inserted fragment was highly isogenous with Japan ABO11494 strain. The inserted fragment was labeled with digoxigenin. Segment of liver, spleen, kidney, stomach and intestine tissues from 22 patients dead of liver diseases were detected by in situ hybridization with this digoxigenin labeled TTV DNA probe. RESULTS: TTV DNA was detected in 8 livers, 4 kidneys, 3 spleens, 2 intestines, and 2 stomachs. The positive cells of TTV DNA in livers were higher than that in other tissues. No obvious pathological topographical relationship of tissue inflammatory reaction with positive cells was found. CONCLUSION: TTV can infect hepatic and ex-hepatic tissues and may cause persistent infection.

Adolescent↗
PubMed2000

[The frequency distribution and establishment of fruit fly strain of segregation distorter in Drosophila melanogaster in China].

Segregation Distorter (SD) is a meiotic drive system of natural occurrence. Heterozygous SD/SD+ males transmit the SD chromosome in vast excess over the normal homolog. SD chromosomes have been recovered at low frequency (1%-5%) from almost every population that has been screened for them in many places of the world. To examine whether there is SD system in natural populations of Drosophila melanogaster in China, we surveyed a few populations of D. melanogaster in Beijing and Qingdao respectively. The results suggested that SD is also found in every population examined at frequency of 1%-5%. On the basis of learning distribution of SD in China, we established a fruit fly stoch of SD from wild population of D. melanogaster in Beianhe district of Beijing. Furthermore, instead of using traditional genetic hybridization, we used molecular approach, PCR, to examine the distribution of SD chromosomes, which has been proved a very effective, quick and convenient method.

Animals↗
PubMed2000

[Long-term results of combined therapy for primary osteosarcoma in extremities].

OBJECTIVE: To evaluate the survival rates, functional outcome, and complications between the combined and non-combined treatment of primary osteosarcoma of the extremities. METHOD: From 1977 through 1992, 170 patients with high-graded, nonmetastatic osteosarcoma were treated. Their average age at diagnosis was 21 years old (ranging from 6 to 52). Tumors were observed at distal femurs in 80 patients (47%), proximal tibia in 51 (30%), proximal humors in 10 and other locations in 22. Combined therapy (en bloc resection of tumor with preoperative and postoperative neoadjuvant chemotherapy) was given 104 patients and non-combined therapy (tumor resection only) to 66. Ninety-four patients underwent limb salvage surgery. In 76 patients who received amputations or disarticulations 33 received chemotherapy. RESULTS: The 5-and 10-year-survival rates were 61% and 53% in the combined therapy group and 28% and 26% in the non-combined therapy group. Local recurrence rate was 23% in limb salvage surgery group and 5.2% in amputation group. Functional evaluation of 80 patients showed that the patients who underwent salvage surgery had higher functional scores than those who had an amputation according to MSTS scoring system (1993). The average scores reached 71% in the salvage surgery group and 53% in the amputation group. CONCLUSIONS: In this study, long-term that combined therapy raised the survival rate of the patients with osteosarcoma. The ase of en bloc resection of bone tumor and reconstructive technique, has enable limb salvage procedures possible to produce excellent functional outcomes. The patients who well have responses to preoperative chemotherapy may have a higher survival rate.

Adolescent↗
PubMed2000

[Telangiectatic osteosarcoma: report of 10 cases].

OBJECTIVE: To raise the level of early diagnosis of telangiectatic osteosarcoma (TOS). METHODS: Ten patients with TOS were treated from July 1991 to December 1998. The patients included men 6 and 4 women, aged from 4 to 44 years (average 23.7 years). The lesions were located at the proximal femur (1 patient), distal femur metaphysis (2), femur shaft (1), proximal tibia metaphysis (2), distal tibia (1) and humerus shaft (3). Preoperative pathologic examination showed two cases of TOS by open biopsy(negative by needle biopsy); the rest were found negative (2 patients), metastasis (1), and sarcoma (5) by needle biopsy. Eight patients received preoperative chemotherapy. Operations including limb-salvage (3) and amputation (7) were performed in all patients. All patients accepted postoperative chemotherapy. RESULTS: 10 Follow-up for a mean of 28 months (range 6 - 72 months) showed no local recurrences: disease-free in 4 patients and pulmonary metastasis in, 6, of whom 5 died and 1 is still alive with lung metastasis. CONCLUSION: TOS is often misdiagnosed and needs early diagnosis and correct treatment under the cooperation of clinicians, radiologists and pathologists.

Adolescent↗
PubMed2000

[Relationship between folate, vitamin B12, total plasma homocysteine and mutation of reductase].

OBJECTIVE: To study relationship between serum and red blood cell (RBC) folate, serum vitamin B(12) (VB(12)), total plasma homocysteine (tHcy), thermolabile genotypes, and activity of methylene-tetrahydrofolate reductase (MTHFR). METHODS: Thirty-four non-pregnant and healthy mothers who gave birth to babies with neural tube defects (NTDs) and 42 mothers to normal babies previously were chosen. Plasma tHcy, RBC and serum folate, serum VB(12), activity of MTHFR and thermolabile genotypes were determined for all of them. RESULTS: There was no significant difference in plasma tHcy, RBC and serun folate between case and control groups. Serum VB(12) was significantly lower in mothers of babies with NTDs than in those with normal ones. Plasma tHcy correlated with RBC folate inversely (P < 0.05). Mean plasma tHcy for thermolabile homozygous mutation of MTHFR was significantly higher than that for either heterozygous mutation or wild homozygous mutation (P < 0.001). There was no significant difference in serum folate between groups with varied MTHFR genotypes. Plasma tHcy was slightly greater in those with lower serum folate than in those with higher one, and correlated inversely with activity of MTHFR. CONCLUSIONS: Increase in plasma tHcy correlates with homozygous mutation of thermolabile MTHFR and decrease in activity of MTHFR. Higher level of folate in the body can interfere the relationship between plasma tHcy and activity of MTHFR.

Adult↗
PubMed2000

[Experimental study of Ti-75(AlMoZrTi alloy) dental implants in dog mandible].

OBJECTIVE: The purpose of this study was to investigate the biocompatibility of Ti-75(AlMoZrTi Alloy) dental implants. METHODS: Four 6.5 to 16 kg dogs were used,after mandibular cuspids and premolar extraction, 16 implants were placed and left for six or twelve months. All of the dental implants were made of Ti-75 (AlMoZrTi Alloy) and they were manufactured in two types-nonsubmerged and submerged threaded implants. RESULTS: The survival rate of the implants was 100% (submerged implants) and 91.7% (nonsubmerged implants). Histologically,all survival implants showed some degree of intimate bone to implant contact, but one of the nonsubmerged implants showed periimplantitis. No implants were observed to be mobile. The periotest values of the dental implants were near the periotest values of the nature teeth. CONCLUSION: This study demonstrated Ti-75 is a biocompatible material and periotest is worthy of detection of osseointegration.

English Abstract↗
PubMed1999

HRad17 colocalizes with NHP2L1 in the nucleolus and redistributes after UV irradiation.

The rad17 gene of Schizosaccharomyces pombe plays an important role as a checkpoint protein following DNA damage and during DNA replication. The human homologue of S. pombe rad17, Hrad17, was recently identified, but its function has not yet been established. Using the yeast two-hybrid system, we determined that HRad17 can interact with a nucleolar protein, NHP2L1. This interaction was also demonstrated biochemically, in human cells. Immunofluorescence studies revealed that HRad17 and NHP2L1 colocalize to the nucleolus, and immunogold labeling further resolved the location of NHP2L1 to the dense fibrillar component of the nucleolus. Interestingly, the localization of HRad17 in the nucleolus was altered in response to UV irradiation. These results provide some insight into the DNA damage and replication checkpoint mechanisms of HRad17.

Amino Acid Sequence↗
PubMed1999

Human PIR1 of the protein-tyrosine phosphatase superfamily has RNA 5'-triphosphatase and diphosphatase activities.

A human cDNA was isolated encoding a protein with significant sequence similarity (41% identity) to the BVP RNA 5'-phosphatase from the Autographa californica nuclear polyhedrosis virus. This protein is a member of the protein-tyrosine phosphatase (PTP) superfamily and is identical to PIR1, shown by Yuan et al. (Yuan, Y., Da-Ming, L., and Sun, H. (1998) J. Biol. Chem. 272, 20347-20353) to be a nuclear protein that can associate with RNA or ribonucleoprotein complexes. We demonstrate that PIR1 removes two phosphates from the 5'-triphosphate end of RNA, but not from mononucleotide triphosphates. The specific activity of PIR1 with RNA is several orders of magnitude greater than that with the best protein substrates examined, suggesting that RNA is its physiological substrate. A 120-amino acid segment C-terminal to the PTP domain is not required for RNA phosphatase activity. We propose that PIR1 and its closest homologs, which include the metazoan mRNA capping enzymes, constitute a subgroup of the PTP family that use RNA as a substrate.

Acid Anhydride Hydrolases↗
PubMed1999

HRad17, a human homologue of the Schizosaccharomyces pombe checkpoint gene rad17, is overexpressed in colon carcinoma.

Using the palindromic PCR-cDNA display method, we have cloned a novel gene overexpressed by human colon carcinoma relative to normal colon. Among normal tissues examined, only testis expresses it at a high level. Sequence analysis revealed its extensive homology with checkpoint genes rad17 of Schizosaccharomyces pombe and RAD24 of Saccharomyces cerevisiae. This novel gene designated as hRad17 is localized to chromosome 5q12,13.1, a region known to be deleted in a variety of human cancers. Promoter region and one pseudogene of hRad17 have been identified. Whereas the increased expression of hRad17 by human colon carcinomas may be related to the known resistance of these cells to DNA-damaging agents during therapy, the deletion of hRad17 in a variety of cancers may predispose them to increased rate of mutation and heightened sensitivity to DNA-damaging agents, including radiation and anticancer drugs.

Animals↗
PubMed1999

[Implication of mutation of hepatitis C virus 1b interferon sensitivity determining region(NS5A aa 2209-2248) response to interferon alpha therapy in patients with chronic hepatitis C].

Hepatitis C virus (HCV) isolates from 12 patients with chronic hepatitis C underwent the sequence analysis. Among the 12 patients, 9 obtained a complete response (CR), 2 partial response (PR) and 1 non--response (NR) after the treatment with IFN-alpha. The results showed that only single amino acid (aa) substitution in iIFN sensitivity determining region (ISDR) (aa 2213 and aa 2218) in 6 cases with CR was observed, while 3 cases of CR and all PR and NR cases had no aa mutation of ISDR. It is suggested that the ISDR in HCV NS5A was yet not identified by our patients.

Adult↗
PubMed1999

A bacterial haloalkane dehalogenase gene as a negative selectable marker in Arabidopsis.

The dhlA gene of Xanthobacter autotrophicus GJ10 encodes a dehalogenase which hydrolyzes dihalo- alkanes, such as 1, 2-dichloroethane (DCE), to a halogenated alcohol and an inorganic halide (Janssen et al. 1994, Annu. Rev. Microbiol. 48, 163-191). In Xanthobacter, these alcohols are further catabolized by alcohol and aldehyde dehydrogenase activities, and by the product of the dhlB gene to a second halide and a hydroxyacid. The intermediate halogenated alcohols and, in particular, the aldehydes are more toxic than the haloalkane substrates or the pathway products. We show here that plants, including Arabidopsis, tobacco, oil seed rape and rice, do not express detectable haloalkane dehalogenase activities, and that wild-type Arabidopsis grows in the presence of DCE. In contrast, DCE applied as a volatile can be used to select on plates or in soil transgenic Arabidopsis which express dhlA. The dhlA marker therefore provides haloalkane dehalogenase reporter activity and substrate dependent negative selection in transgenic plants.

Arabidopsis↗
PubMed1999

[Curettage plus cement reconstruction for treating giant cell tumor of limbs].

OBJECTIVE: To evaluate curettage plus cement reconstruction in the treatment of giant cell tumor (GCT) of limbs. METHODS: 125 patients with GCT of limbs were treated with curettage plus cement reconstruction. They were 62 men and 63 women aged from 12 to 71 years, 101 patients had primary GCT and 24 had recurrence of GCT. The recurrence at the knee was noted in 100 patients (80%). RESULTS: 125 patients were followed-up for 96 months (range 13 - 194 months). The recurrence rate was 12.7% in the primary group and 10.3% in the recurrent group. Two patients were infected. Joint functions were excellent. CONCLUSIONS: Curettage plus cement reconstruction is safe and effective in treating local GCT of limbs. The key the method is aggressive curettage of the lesion via a bone window. Cement is adjuvant therapy only.

Adolescent↗
PubMed1998

Human thymocyte dipeptidyl peptidase IV (CD26) activity is altered with stage of ontogeny.

The nonintegrin receptor CD26, also known as dipeptidyl peptidase IV (DPP IV) is a transmembrane 110- to 120-kDa serine aminopeptidase glycoprotein with multiple functions, including cellular trafficking through extracellular matrix, and costimulatory potential during T cell activation, and is an influence upon T cell differentiation during their maturation in the thymus. In order to further define the expression and functional activity of this membrane exopeptidase in human thymus, we utilized a nondisruptive, cytofluorogenic assay which allowed simultaneous measurement of intracellular DPP IV activity using a fluorochrome-conjugated peptide substrate with surface staining of plasma membrane-associated T lymphocyte lineage antigens CD4 and CD8, as well as CD26. Human thymi were examined using the three-color assay, and significant differences in time-dependent DPP IV activity were found among the thymocyte subsets defined by their CD4/CD8 phenotype. In this regard, CD4(-)/CD8(-) thymocytes displayed the lowest DPP IV activity and had higher activity than the smaller-sized CD26(+) cells. Thymocytes containing greater percentages of apoptotic cells expressed lower DPP IV activity than viable cells. Thus, DPP IV appears to be upregulated as thymocytes mature and is reduced among thymocyte populations enriched for cells undergoing programmed cell death, suggesting that CD26-associated enzymatic activity is ontogenically controlled during T cell maturation and may be involved in thymic deletion of emerging clones.

Apoptosis↗
PubMed1998

Peripheral human T lymphocyte maintenance of immune functional capacity and phenotypic characteristics following in vivo cocaine exposure.

The effects of cocaine exposure upon the host's immune response is equivocal since a variety of studies have generated conflicting conclusions, often as the result of differences between in vitro and/or animal models and the actual conditions experienced in humans who are acutely abusing this drug. To further address this issue, we have studied a group of patients who were positive for cocaine or cocaine metabolites and we evaluated a variety of functional parameters of T-lymphocytes and other peripheral lymphoid cell populations, as well as immunophenotypic characteristics of these cells. When compared to normal controls and patients who were negative for cocaine, we found that the cocaine-positive patients had T-cell functional assays which were essentially normal, with the exception of a slight depression in PHA stimulation. Likewise, the immunophenotype of the peripheral blood lymphocytic populations showed normal percentages and numbers of their T cell subsets (CD4, CD8), NK cells, and B cells. Multicolor flow cytometry analysis revealed no difference in T cell subpopulations positive for the "memory" marker, CD62L. No correlation could be established between levels of cocaine or cocaine metabolites and any phenotypic, demographic, or functional parameter. In summary, these results demonstrate that individuals acutely exposed to cocaine do not show markedly altered T cell function or fluctuations in phenotypically identified cell populations. These studies imply that acute cocaine exposure does not predispose individuals to grossly apparent immunosuppression. However, the possibility that subtle, transient, or more specific changes in the immune system may be incurred by use of cocaine, particularly with chronic exposure, remains to be determined.

Adult↗
PubMed1997

The noncatalytic C-terminal segment of the T cell protein tyrosine phosphatase regulates activity via an intramolecular mechanism.

Human T cell protein tyrosine phosphatase (TCPTP) is a nontransmembrane enzyme, the first of the protein tyrosine phosphatase family to be cloned. Alternative mRNA splicing results in variation in the sequence at the extreme C terminus of TCPTP and generates a 45-kDa form (TC45) that is targeted to the nucleus and a 48-kDa variant (TC48) associated with membranes of the endoplasmic reticulum. In this report, we assessed the role of the C-terminal, noncatalytic segment of TCPTP in regulating activity, concentrating primarily on the TC45 variant. We have demonstrated that limited tryptic proteolysis of TC45 releases first a 42-kDa fragment, then a 33-kDa catalytic domain. Using reduced carboxyamidomethylated and maleylated lysozyme as substrate (RCML), the catalytic domain displays 20-100-fold more activity than the full-length enzyme. Analysis of the time course of limited trypsinolysis revealed that proteolytic activation occurred following cleavage of a protease-sensitive region (residues 353-387) located at the C terminus of TC45. The activity of truncation mutants illustrated that removal of 20 C-terminal residues was sufficient to activate the enzyme fully. The 33-kDa catalytic domain, but not the full-length enzyme, was inhibited in a concentration-dependent manner by addition of the noncatalytic C-terminal segment of TC45. A monoclonal antibody to TCPTP, CF4, which recognizes an epitope located between residues 350 and 363, was capable of fully activating TC45. These data indicate that the noncatalytic segment of TC45 contains an autoregulatory site that modulates activity via a reversible intramolecular interaction with the catalytic domain. These studies suggest that the C-terminal noncatalytic segment of TC45, and possibly TC48, may not only direct the enzyme to different subcellular locations but may also modulate activity in response to the binding of regulatory proteins and/or posttranslational modification.

Amino Acid Sequence↗
PubMed1997

Dipeptidyl peptidase IV (CD26) activity in human alloreactive T cell subsets varies with the stage of differentiation and activation status.

Dipeptidyl peptidase IV (DPP IV), also known as CD26, is a transmembrane serine aminopeptidase which has an ontogenically related expression on T cells and participates on several immunological functions. CD26 appears to play an important role in alloimmunity during host T cell activation subsequent to alloantigen encounter and is a way by which effector T cells traverse graft endothelial barriers. In order to help to elucidate the role of the CD26 molecule in alloimmune responses, DPP IV activity and CD26 antigenic expression were assessed during the initial phases of completely MHC-disparate human mixed lymphocyte reactions (MLRs) and in several long-term alloreactive T cell clones. Our methods involved the use of a rhodamine-110-conjugated dipeptide substrate specific for DPP IV in two-colour cytofluorographic analysis that allowed stimultaneous lineage marker evaluation. Polyclonal populations of alloreactive CD4 and CD8 T cells contained DPP IV activity at 1 and 10 min of incubation that was variably elevated from resting T cells with the enzyme activity confined to CD26+ cells. T cell clones derived from MLRs were established with IL-2 supplementation and alloantigen restimulation and had reduced CD62L expression with functional specificity to the stimulating MHC. While CD26 expression remained stable, DPP IV activity was variable in the alloreactive T cell clones, with enzyme function in the latter appearing to coincide with the timing of alloantigen restimulation. These studies demonstrate that DPP IV activity varies among phenotypically distinct alloreactive T cell subsets and appears to be altered with the activation status of the effector cells. These findings raise the potential of a role for CD26/DPP IV in the generation of specific alloimmunity. With this methodology, it may be possible to reveal whether specific alterations in the activity of this molecule in T cell populations promote graft acceptance and to determine the molecular requirements for these changes.

CD4-Positive T-Lymphocytes↗
PubMed1997

Western blotting of NC1 type IV collagen fragments in human plasma.

Collagen IV matrix of glomerular basement membrane may be involved in the development of various renal diseases, e.g. diabetic nephropathy. An immunoblotting method for the detection of the carboxy-terminal non-collagenous (NC1) domain of type IV collagen in plasma was developed. The high sensitivity down to the picogram range enabled characterization of NC1(IV) fragments in human blood for the first time. Both Western blotting and gel filtration chromatography coupled with an enzyme-linked immunoassay surprisingly revealed that the NC1(IV)-related components are bound to the fibrin clot forming during blood coagulation. About 40% of the NC1(IV) fragments in plasma had an apparent molecular mass higher than 340,000. Abnormal NC1(IV) immunoblot patterns were observed in about 50% of patients with insulin-dependent (n = 20) and non-insulin-dependent (n = 20) diabetes mellitus compared with less than 7% in healthy control subjects (n = 30). There were no obvious associations between abnormal immunoblots and stage of nephropathy or glycaemic control in diabetic subjects.

Adult↗