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Biomedical subjects

L Xu

Publications and source records attributed to L Xu.

At least 721 records · Page 40Linked to original sources
PubMed1994

[Study on antibacterial protein from human urinary bladder mucosa].

Acid-soluble extract of human bladder mucosal surface was obtained by washing out the bladder of accidentally dead male human with 1% acetic acid in the presence of proteinase inhibitors. Acid urea polyacrylamide gel electrophoresis (AU-PAGE) indicated that the acid-soluble extract had more than 10 main protein bands, but the currently known antibiotic peptides, e. g., Lysozyme and defensins, were not found in this extract. The quantitation assay of lysozyme showed that lysozyme only amounted to 2.2 microgram per milligram protein. When tested for antibacterial activity by using ultrasensitive radial diffusion assay, the acid-soluble extract effectively killed E. coli ML-35P. The antibacterial activity of the acid-soluble extract was further analysed by gel overlay technique and the result showed that one main protein band, which was referred to as human bladder protein (HBP), was potently antibacterial against E. coli ML-35P. The HBP accounted for 4% of the total acid-soluble extract protein. These results suggest that the presence of antibacterial protein in the bladder mucosa may be the molecular base of the bladder antibacterial defence mechanisms.

Adult↗
PubMed1994

[Detection of antibodies against Legionella pneumophila from pleural effusion--a case report of Legionnaire's pneumonia with pleural effusion].

Using TAT and ELISA, 50 samples of pleural effusion and sera from patients infected with non-Legionella pneumophila were detected for antibodies against Legionella pneumophila serogroups 1 and 6, respectively. The average titre and upper limit value (99%, mean + 2.326S) calculated. In addition, a pleural effusion and a serum from a patient with Legionnaire's pneumonia were also detected by TAT and ELISA. The result showed that the titre of this antibody in his pleural effusion was not only over the upper limit, but also higher than that in his serum.

Adolescent↗
PubMed1994

[Characteristics of reversed optic cupping in glaucoma after reduction of intraocular pressure].

Quigley's hypothesis indicates that the dense connective tissue is the least and the pores of the lamina cribrosa are the largest at the superior and inferior poles of the lamina cribrosa, therefore they are the most vulnerable locations to be involved by the characteristic glaucomatous optic nerve damage. To get clinical evidences of the hypothesis, the reversal or contraction of glaucomatous optic cup after reduction of intraocular pressure (IOP) was examined (The change is primarily caused by intraocular hypertension--induced distortion and posterior ectasia of the lamina cribrosa which moves forward reversely, leading to dilated optic cup contraction.). The method of examination was a stereoscopic flicker comparison with a computerized image system, alternatively displaying superposed 2 serial stereo pairs rapidly and the changing part presenting jumping appearance. Under stereoscopic observations, the changes of 3-dimension optic cup end be seen and the false positive phenomena caused by photographic angle variation, vascular pulsation, etc. can be differentiated from the characteristic changes of the cup. Stereo fundus photographs were taken from 31 eyes with high intraocular pressures before and after treatment for reduction of IOPs which was either diamox administration or trabeculectomy. The results show that the reversal of optic cups after reduction of IOPs are mostly asymmetrical, especially at the superior and/or inferior poles. By multiple stepwise regression, it is known that the amount of the change is only correlated with the initial IOP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Bone mass, rates of osteoporotic fractures, and prevention of fractures: are there differences between China and Western countries?

Fractures are one of the most common causes of disability in older women. The quantity and density of bone decreases with age. Most types of fractures increase as bone density declines. But most of the knowledge about causes and prevention of fractures comes from studies performed in Western countries. Asian women appear to have similar or slightly lower bone density that may be a result of their smaller size. They appear to have a lower risk of hip fracture than Whites, which may be a result of their shorter hip axis. The risks of other types of fractures in Chinese women is less well defined and reasons for differences in the rates of osteoporotic fractures between China and Western countries remain to be explored. A study is underway in Beijing to describe the risks and potential causes of fractures among older women in urban China. Randomized trials in Western countries have demonstrated that calcium and vitamin D, estrogen, calcitonin, or bisphosphonates can reduce the rate of fractures. increased intake of calcium and vitamin D may be the most effective approach to preventing fractures in China, but this should be tested in a randomized trial.

Asian People↗
PubMed1994

[Cloning and screening on tumor-related genes inactivated in rat hepatoma cells].

The paper describes an experiment screening tumor-related genes which specifically expressed in rat normal liver cells but inactivated in hepatoma cells with subtractive hybridization technique. During the test, subtracting normal liver cDNA with hepatoma mRNA produces probe-A whereas subtracting hepatoma cDNA by normal liver mRNA gives probe-B. The paper shows six cDNA fragments (TR 1-6) which hybridize probe-A preferentially obtained through dot-blot screening of 2500 colonies with the two probes. Among TR 1-6, special expressions of TR 2 and TR 4 in normal liver cells are further analyzed.

Animals↗
PubMed1994

[The prognostic value of thyroid stimulating antibodies after antithyroid drug treatment of Graves' disease].

Thyroid stimulating antibodies (TsAb) and thyrotropin releasing hormone (TRH) test were used as the indices for predicting relapse and remission in 58 patients. The variation of TsAb activities was observed before and after antithyroid drug (ATD) treatment. The findings showed that TsAb activities of untreated patients were significantly higher than those of patients treated by ATD, and TsAb activities were weak or negative after ATD treatment. When TsAb was positive or TRH test was abnormal at the time of cessation of ATD therapy, nearly 93% patients relapsed. Further analyses of relapsed patients indicated that there was no correlation between the two indicators, and the TsAb positive rate (84%) was significantly higher than the rate of abnormal TRH test (45%). The average ATD treatment duration in relapsed patients was shorter than that in remission patients. It is concluded that TsAb is more useful than TRH test when they are used for predicting the prognosis of Graves' disease. The duration of ATD treatment could affect relapse or remission. The immunosuppression effect of ATD was also identified.

Adult↗
PubMed1994

Expression of human glucocerebrosidase in murine macrophages: identification of efficient retroviral vectors.

Gaucher's disease is an autosomal recessive disorder characterized by a functional deficiency in beta-glucocerebrosidase enzymatic activity and the resultant accumulation of the glycolipid glucocerebroside in macrophages. Due to the nature of the affected cells, Gaucher's disease is an excellent candidate for gene therapy of hematopoietic stem cells and autologous bone marrow transplantation of transduced cells using retroviral vectors containing the glucocerebrosidase (GC) gene. In order to identify a retroviral vector capable of high levels of expression of the GC gene in macrophages, we have used the murine myeloid leukemia cell line, M1, a cell line that can be differentiated with interleukin-6 (IL-6) from blasts to macrophages. Two vectors use the Moloney murine leukemia virus (MoMLV) enhancer/promoter (LG vector) or the myeloproliferative sarcoma virus (MPSV) enhancer/MoMLV promoter (MG vector), both located in the viral long-terminal repeat (LTR); the third vector uses the phosphoglycerate kinase (PGK) promoter located internally in the vector (PG vector). The amphotropic PA317 and GP+am12 packaging cell lines were used as virus producer cells, and the GP+am12 cell line demonstrated higher titers, higher levels of GC protein expression, and specific GC enzymatic activity as well as higher transduction efficiencies for all three vectors. The LG retroviral vector was the most efficient in transducing the M1 cells. On average, higher levels of RNA and protein expression were seen in the M1 clones transduced with the LG vector, and these levels increased after differentiation. Thus, the LG retroviral vector in which the expression of the GC gene is driven by the MoMLV LTR enhancer/promoter is the best vector of the three studied for future studies for gene therapy of Gaucher's disease and other hematopoietic disorders that involve macrophages.

Animals↗
PubMed1994

[In vitro and in vivo targeting therapy of immunoliposomes against human gastric cancer].

Nine kinds of antineoplastic agents and 2 boron-10 compounds were encapsulated respectively into the immunoliposomes targeted with monoclonal antibody, MGb2, against human gastric cancer. The immunoliposomes were characterized in vitro and in vivo with different nude mouse xenograft models and different routes of administration. The immunore activity was well preserved. The diameter was 100nm for reverse-phase evaporation vesicles and 35nm for small unilamellar vesicles. 1,000-10,000 molecules of antitumor agent were entrapped and 30-80 molecules of MGb2 incorporated per one liposome. They showed selective cytotoxicity to human gastric cancer cell SGC-7901 but very low toxicity to human normal embryonic lung cell SL7. Biodistribution studies indicated that both were better than non-specific liposomes and free drugs. Boronated immunoliposomes could carry boron-10 specifically to SGC-7901 and showed targeted boron neutron capture therapy effects after thermal neutron irradiation. The results confirmed the specific antitumor effects of immunoliposomes in vitro and in vivo and demonstrated the potentiality of the immunoliposomes in the targeting therapy of human gastric cancer.

Animals↗
PubMed1994

[Psychological aspects of infertile couples in China].

From March 1991 to February 1992, a psychological interview survey was performed among 652 women and 425 of their husbands who came to the Female Infertility Clinic in PUMC Hospital to seek consultation and treatment for their infertility. The results showed that more than 80 percent of the couples had been tolerating various psychological stresses caused by infertility. Disapproval was the most common feeling. The couples' emotion was influenced by each other. Emotional scores of husbands and wives were significantly positive correlated (P < 0.001). However, men are more capable to cope with this problem than women. Men's attitude to infertility is more positive and optimistic than women. There is no significant difference between women and men in their attitude to the treatment and forecasting of prognosis. Cultural background is a major factor associated with psychological stresses of infertile couples. Infertility has more severe impact on people living in rural areas as well as ones with lower level education. Infertility also affected couple's sexual and marital relationships. The relationship between women and their parents in-laws became worse among 8.6 percent of infertile women. About one-third of female participants thought the examination and the treatment for infertility also developed some emotional stresses and psychological burdens. Infertility may create various psychological stresses and influence the effect of treatment. Therefore, the management of infertility should not only include physical treatment but also understanding, sympathy and support, all above should not be neglected.

Adult↗
PubMed1994

Correction of the enzyme deficiency in hematopoietic cells of Gaucher patients using a clinically acceptable retroviral supernatant transduction protocol.

Gaucher disease is a lysosomal storage disorder caused by a deficiency of the enzyme glucocerebrosidase (GC), and is an excellent candidate for gene replacement therapy. To develop a clinically acceptable protocol for this purpose, we created two amplified (A) high-titer retroviral vector-producer cell lines to efficiently transduce hematopoietic stem and progenitor cells. GP+envAm12/A-LGSN (A-LGSN), contained the GC cDNA driven by the retroviral long terminal repeat (LTR) and the neomycin phosphotransferase gene expressed from the simian virus 40 early promoter. GP+envAm12/A-LG4 (A-LG4) contained only the GC gene driven by the LTR. Both A-LGSN and A-LG4 contained multiple proviral copies and gave approximately 10-fold higher titers on 3T3 cells compared to their unamplified counterparts. These vectors were packaged in GP+envAm12 cells because vectors produced in this cell line transduced hematopoietic cells more efficiently than other packaging cells tested. Bone marrow mononuclear cells and purified CD34+ cells were infected with virus supernatants four times in the presence of interleukin-3 (IL-3), IL-6, and stem cell factor (SCF) over 96 hours in culture. Cells were then plated in semisolid cultures and colony-forming unit-granulocyte/macrophage (CFU-GM) colonies were scored for vector presence by polymerase chain reaction (PCR). Transduction efficiency of CFU-GM colonies derived from CD34+ cells was improved considerably using the amplified vectors in the GP+envAm12 packaging line. For A-LGSN, A-LG4, and unamplified LGSN, transduction efficiencies were 41, 42, and 25%, respectively. Therefore, multiple proviral copies resulting in higher titer improves retroviral transduction of human hematopoietic progenitor cells. Hematopoietic cells from Gaucher patients were transduced and placed into long-term bone marrow culture (LTBMC). Viral supernatant from the amplified producer lines transduced long-term culture initiating cells (LTCIC) efficiently (30 to 50%) using this clinically acceptable protocol. Both sustained mRNA expression and GC enzyme production are achieved in the long-term culture of LTCIC and lead to correction of the GC deficiency in their progeny cells.

Bone Marrow Cells↗
PubMed1993

Reserpine impairs spatial working memory performance in monkeys: reversal by the alpha 2-adrenergic agonist clonidine.

Repeated daily treatment with the catecholamine-depleting agent, reserpine, dramatically reduced performance on the delayed response task, a test of spatial working memory that depends upon the integrity of the prefrontal cortex. Delayed response performance fell from an average of 27.2/30 trials correct before reserpine treatment to an average of 20.4/30 trials correct after repeated reserpine administration. Injection of the alpha 2-adrenergic agonist, clonidine (0.0001-0.05 mg/kg), to chronic reserpine-treated monkeys significantly restored performance on the delayed response task; performance after an optimal dose averaged 27.8/30 trials correct. Clonidine's beneficial effects on delayed response performance were longlasting; monkeys remained improved for more than 24 h after a single clonidine injection. The finding that clonidine is efficacious in reserpinized animals supports the hypothesis that alpha 2-adrenergic agonists improve cognitive function through actions at postsynaptic, alpha 2-adrenergic receptors on non-adrenergic cells. In contrast to the delayed response task, reserpine had little effect on performance of a visual discrimination task, a reference memory task which does not depend on the prefrontal cortex. These results emphasize the importance of postsynaptic, alpha 2-adrenergic mechanisms in the regulation of working memory.

Adrenergic alpha-Agonists↗
PubMed1993

Elevated glucose and angiotensin II increase 12-lipoxygenase activity and expression in porcine aortic smooth muscle cells.

The lipoxygenase (LO) pathway of arachidonate metabolism has been suggested to play a key role in atherosclerosis and in mediating several actions of angiotensin II (AII). However, the relationship between LO activation and factors linked to accelerated diabetic vascular disease such as hyperglycemia and AII is not known. We have investigated the effect of high glucose (HG; 25 mM) and AII on LO activity as well as LO protein and mRNA expression in porcine aortic vascular smooth muscle cells (PVSMCs). We observed that cells cultured in HG had significantly higher levels of the cell-associated LO products 12- and 15-hydroxyeicosatetraenoic acids (HETEs). AII added to cells grown in HG specifically further increased only cell-associated 12-HETE levels. Using immunoblot analysis and reverse transcriptase PCRs, we demonstrated the presence in PVSMCs of porcine leukocyte-type 12-LO protein and mRNA, respectively. Furthermore, the levels of both were markedly upregulated by AII as well as by HG. These studies suggest that enhanced 12-LO activity and expression are mechanisms for accelerated vascular disease produced by HG and AII in diabetes mellitus.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1993

Conserved cysteine residues of Oct-2 POU domain confer sensitivity to oxidation but are dispensable for sequence-specific DNA binding.

The POU family of proteins, including the Oct-2 transcription factor, is characterized by a highly conserved bipartite DNA binding domain containing a 'POU homeodomain', distantly related to homeodomains of other DNA binding proteins, and a 'POU specific' domain unique to this class of factors. Prompted by the finding that in vitro DNA binding by Oct-2 is reversibly inhibited by oxidation of the protein, we investigated the role of the cysteine residues in the POU domain. All POU homeodomains identified contain a cysteine in the helix 3 region presumed to contact DNA directly; many (including Oct-2) also contain a less-well conserved cysteine residue(s) in the POU specific domain. Replacement of these cysteines with serine residues rendered the DNA binding domain resistant to oxidation but did not appreciably change the binding to a canonical octamer sequence, suggesting that the conserved cysteine residues are not required for sequence-specific DNA contacts, but may be important for another function.

Amino Acid Sequence↗
PubMed1993

Parapapillary chorioretinal atrophy in normal-pressure glaucoma.

Parapapillary chorioretinal atrophy has been shown to be associated with glaucomatous optic nerve damage. We sought to determine whether eyes with normal-pressure glaucoma have an unusually large parapapillary atrophy as compared to eyes with primary open-angle glaucoma. Color stereoscopic optic disk photographs of 34 patients with normal-pressure glaucoma and 283 patients with primary open-angle glaucoma were morphometrically analyzed. Both groups were matched for neuroretinal rim area and visual field loss. Severely myopic eyes were excluded. The parapapillary atrophy was differentiated into a peripheral Zone Alpha with irregular pigmentation and a central Zone Beta with visible sclera. Zones Alpha and Beta did not differ significantly between the two groups in either frequency or size. Eyes with normal-pressure glaucoma do not have an abnormally large parapapillary atrophy as compared to eyes with primary open-angle glaucoma, which is diagnostically and pathogenetically important.

Adult↗
PubMed1993

Replacement of germ-line epsilon promoter by gene targeting alters control of immunoglobulin heavy chain class switching.

Recent work has shown that the ability of cytokines to direct immunoglobulin heavy chain class-switch recombination to particular heavy chain constant (C) region (CH) genes correlates with the induction of specific germ-line CH transcripts. To test the role of germ-line transcripts in class switching, we have used homologous recombination to mutate the immunoglobulin heavy chain locus of the 18.81A20 murine pre-B-cell line. In the parent cell line, the combination of interleukin-4 (IL-4) and lipopolysaccharide (LPS) induces germ-line epsilon locus transcription prior to class switching to epsilon. The heavy chain locus of the mutated cell line contains the immunoglobulin heavy chain enhancer and variable region gene promoter in place of the LPS/IL-4-responsive germ-line epsilon promoter. The mutant cell line constitutively transcribes the epsilon locus in the absence of IL-4. Strikingly, the mutant cell line also switches to epsilon in the absence of IL-4. This result demonstrates that, at least in the 18.81A20 cell line, germ-line epsilon transcription plays a direct role in class switching to the epsilon locus. In addition, the ability to change the pattern of class switching by altering transcriptional activity indicates that transcription of germ-line CH is mechanistically important in regulation of class switching.

Abelson murine leukemia virus↗
PubMed1993

Structure and polymorphisms of the human annexin III (ANX3) gene.

A 75-kb region encompassing the human annexin III (ANX3) gene on chromosome 4q21 was characterized from directly amplified genomic DNA and from six genomic clones in phage lambda (lambda ANX3-1 to lambda ANX3-6). The gene was mapped with restriction enzymes BamHI, EcoRI, HindIII, SacI, and XbaI, and primers were developed for nine sequence-tagged sites throughout the gene. The transcribed region spans 58 kb and contains 12 introns ranging from 0.3 to 19.1 kb and 13 exons ranging from 53 to 374 bases. Northern blots showed a single mRNA species of approximately 1.7 kb in all tissues examined. Three intragenic polymorphisms were identified: a tandem repeat of the sequence TAAA with at least six alleles, a two-allele SalI polymorphism detectable by polymerase chain reaction, and a two-allele BglII polymorphism.

Amino Acid Sequence↗