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Biomedical subjects

X Liang

Publications and source records attributed to X Liang.

At least 181 records · Page 10Linked to original sources
PubMed1998

[Detection of presymptomatic patients and heterozygotes with Wilson's disease by using haplotypes of microsatellites].

OBJECTIVE: To develop a rapid, exact and effective technique of gene diagnosis for the early diagnosis of patients with wilson's disease(WD) and detection of WD heterozygotes. METHODS: Five microsatellite (or short tandem repeat, STR) loci at D13S301, D13S316, D13S296, AFM238vc3 and AFM184xc5 were amplified by polymerase chain reaction(PCR). D13S301 was a locus within WD gene, the others were in the flank of WD gene. After detection of amplified fragment length polymorphism of the five STR loci with denaturing polyacrylamide gel electrophoresis(AFLP-PAGE), the STR haplotypes analyses were performed on 120 members in 23 WD families. RESULTS: The five STR loci had high polymorphism information content(PIC). PICs of D13S301, D13S316, D13S296, AFM084xc5 and AFM238vc3 were 0.89, 0.93, 0.91, 0.91 and 0.94 respectively. The STR haplotypes analyses confirmed that the two patients previously diagnosed doubtfully were WD patients definitely. Among 31 sibs without any clinical symptoms, 4 were diagnosed as presymptomatic patients, 8 as WD heterozygotes, 17 as normal homozygotes and 2 as doubtful presymptomatic patients. CONCLUSION: Haplotypes analysis of the five STR loci can provide high genetic information. It provides a new important technique in gene diagnosis of WD.

Adult↗
PubMed1997

Comparison of estrogen receptor DNA binding in untreated and acquired antiestrogen-resistant human breast tumors.

Preliminary studies have suggested that measuring the ability of immunoreactive 67-kDa estrogen receptor (ER) to bind DNA and form in vitro complexes with its cognate estrogen response element (ERE) might serve to identify breast tumors most likely to respond to antiestrogens like tamoxifen. Data from two different surveys of untreated primary breast tumors confirmed that only 67% (74 of 111) of ER-positive tumors express a receptor capable of forming ER-ERE complexes by gel-shift assay, with tumors of lower ER content having significantly reduced ER DNA-binding frequency (56%) relative to those of higher ER content (82%; P = 0.007). In contrast to these untreated tumors, a panel of 41 receptor-positive breast tumors excised after acquiring clinical resistance to tamoxifen during either primary (n = 26) or adjuvant therapy (n = 15) showed a significantly greater ER DNA-binding frequency, with nearly 90% capable of forming ER-ERE complexes (P < 0.02). To assess experimentally whether ER DNA-binding function is altered during the development of antiestrogen resistance, nude mouse MCF-7 tumor xenografts were analyzed before and after the acquisition of in vivo resistance to either tamoxifen or a pure steroidal antiestrogen, ICI 182,780. Tamoxifen-resistant MCF-7 tumors retained full expression of 67-kDa DNA-binding ER, and despite a markedly reduced ER content in the ICI 182,780-treated tumors, the expressed ER in these antiestrogen-resistant tumors exhibited full ability to form ER-ERE complexes. These findings indicate that breast tumors with acquired antiestrogen resistance continue to express ER of normal size and DNA-binding ability and suggest that the failure of antiestrogens to arrest tumor growth during emergence of clinical resistance results from an altered gene-regulatory mechanism(s) other than ER-ERE complex formation.

Animals↗
PubMed1997

Functional analysis of the transmembrane anchor region of bovine herpesvirus 1 glycoprotein gB.

In herpesviruses, homologues of glycoprotein B (gB) are essential membrane proteins which are involved in fusion. However, there is no clear evidence regarding the location of the fusogenic domain on gB. By using bovine herpesvirus 1 (BHV-1) as a model, we studied the relationship between the structure and the fusogenic activity of gB. This was achieved by expressing genes of different gB derivatives containing specific truncations at the end of segments 2 or 3 of the transmembrane region in Madin-Darby bovine kidney cells under the control of the bovine heat-shock protein hsp70A gene promoter. All expressed gB products were structurally similar to authentic gB. One truncated form of gB, gBt, which contains residues 1-763, was efficiently secreted. However, gBtM (residues 1-807), which includes the first two segments at the carboxyl terminus, showed unstable retention on the cell surface, whereas gBtMA (residues 1 829), which contains all three membrane-spanning segments, was mostly intracellularly retained with some unstable surface anchorage. Another truncated gB, gBtDAF, which has gB residues 1-763 (gBt) and a human decay-accelerating factor (DAF) carboxyl tail, was also expressed. The DAF fragment provided a signal for the addition of a glycosyl phosphatidylinositol-based membrane anchor, which could target the gBt chimeric protein on the cell membrane. Immunofluorescence staining and pulse-chase kinetic studies support the theory that gBtM, gBtMA, and gBtDAF are retained on nuclear and cellular membranes via different segments of the transmembrane region or the DAF fragment, respectively. For the cells expressing gBt or gBtM, no cell fusion was observed, whereas cells expressing gBtMA clearly showed fusion. However, in gBtDAF cells, the overexpression and cellular accumulation of recombinant gB products did not cause fusion either, which supports our contention that the fusion phenomenon in gBtMA cells is caused by the fusogenic activity of the expressed gBtMA. With the help of sequence analysis, our results indicate that segment 2 of the transmembrane anchor region might be a fusogenic domain, whereas the real anchor is segment 3.

Amino Acid Sequence↗
PubMed1997

Expression, purification, and crystallization of the catalytic domain of protein tyrosine phosphatase SHP-1.

The catalytic domain of SHP-1, a SH2-domain containing protein tyrosine phosphatase, has been crystallized by the vapor diffusion method using polyethylene glycol as the precipitant. The crystals belong to the monoclinic space group P21 with unit cell dimensions a = 42.12 A, b = 87.94 A, c = 43.22 A, alpha = 90.0 degrees, beta = 120.12 degrees, and gamma = 90.0 degrees. There is one catalytic domain of SHP-1 per asymmetric unit. X-ray was diffracted to at least 2.5 A and the crystals are appropriate for high-resolution structure determination.

Binding Sites↗
PubMed1997

Study of immunogenicity and virulence of bovine herpesvirus 1 mutants deficient in the UL49 homolog, UL49.5 homolog and dUTPase genes in cattle.

We previously reported that the bovine herpesvirus 1 (BHV 1) gene homologous to herpes simplex virus gene UL49 is dispensable; nevertheless, a mutant with the UL49 homolog (UL49 h) gene deletion exhibited significantly impaired growth in cell culture. To further evaluate the role of the UL49 h in virus infectivity in the natural host of BHV 1, the pathogenesis of the UL49 h negative mutant was studied in cattle. An additional mutant with a combined defect in UL49 h, UL49.5 h and dUTPase genes was also studied in parallel. We found that both mutants were avirulent in cattle inasmuch as intranasal (i.n.) administration of either mutants induced no apparent clinical disease, nor did animals receiving the mutants shed virus. Following i.n. inoculation with the mutants animals developed low levels of serum neutralizing (SN) antibodies, and were partially protected against wild-type BHV 1 challenge. Intramuscular immunizations with either mutant induced good SN titers, and moreover, they induced nearly complete protection against respiratory challenge with wild-type virus. The results from this study establish that BHV 1 UL49 h is an important virulence factor, and also suggest that deletion of the nonessential viral genes UL49 h, UL49.5 h and dUTPase may be useful in developing recombinant BHV 1 vaccines or BHV 1-based vaccine vectors.

Administration, Intranasal↗
PubMed1997

Spatial-temporal patterns of gene expression in mouse skeletal muscle after injection of lacZ plasmid DNA.

Gene therapy for muscular diseases requires the efficient transfection of a large proportion of myofiber cells within a given muscle. In the present experiments, patterns of beta-galactosidase expression were examined in mouse rectus femoris muscles at various time-points after a single injection of lacZ encoded plasmid DNA. beta-Galactosidase expression was detected 3 h after injection and rose to peak levels at 3-14 days, and then stabilized at lower levels. beta-Galactosidase staining was detected in an average of about 6% (up to 15%) of the total 4000 myofiber cells, and in about 70% of those myofibers located in the discrete area containing the greatest proportion of transfected cells. Soon after injection of DNA encoding cytoplasmic or nuclear-targeted beta-galactosidase, expression was noted predominantly in the myotendinous junction areas, after which beta-galactosidase activity progressed toward the central parts of the myofibers. This preferential transgene expression at the myotendinous junction may result from some unique, local property of the myofiber cells and/or from a restricted diffusion or binding of the injected plasmid DNA at tendinous surfaces. A better understanding of the reasons for this pattern of reporter gene expression in muscle may suggest procedures for increasing the number of myofiber cells transfected by direct DNA injections.

Animals↗
PubMed1997

An OspA-based DNA vaccine protects mice against infection with Borrelia burgdorferi.

Immunization with recombinant OspA protein of Borrelia burgdorferi protects against experimental Lyme disease. In the present study, mice were injected intramuscularly with plasmid DNA (VR2210) encoding strain B31 OspA. In this vector, the ospA-coding sequence was under transcriptional control of the cytomegalovirus immediate early promoter. For negative and positive controls, mice were immunized with either the plasmid vector without an osp-coding sequence or recombinant OspA protein, respectively. Mice immunized with VR2210 DNA produced OspA-specific antibodies that bound to B. burgdorferi in a whole cell ELISA and inhibited the growth of a homologous strain of B. burgdorferi. Immunization with VR2210 protected mice against challenge with 2 infectious strains of B. burgdorferi, Sh-2-82 and N40. These results indicate that vaccination with plasmid DNA expressing OspA is an efficacious method for providing a protective response against B. burgdorferi infection.

Amino Acid Sequence↗
PubMed1997

The Agrobacterium tumefaciens virulence gene chvE is part of a putative ABC-type sugar transport operon.

The Agrobacterium tumefaciens virulence determinant ChvE is a periplasmic binding protein which participates in chemotaxis and virulence gene induction in response to monosaccharides which occur in the plant wound environment. The region downstream of the A. tumefaciens chvE gene was cloned and sequenced for nucleotide and expression analysis. Three open reading frames transcribed in the same direction as chvE were revealed. The first two, together with chvE, encode putative proteins of a periplasmic binding protein-dependent sugar uptake system, or ABC-type (ATP binding cassette) transporter. The third open reading frame encodes a protein of unknown function. The deduced transporter gene products are related on the amino acid level to bacterial sugar transporters and probably function in glucose and galactose uptake. We have named these genes gguA, -B, and -C, for glucose galactose uptake. Mutations in gguA, gguB, or gguC do not affect virulence of A. tumefaciens on Kalanchoe diagremontiana; growth on 1 mM galactose, glucose, xylose, ribose, arabinose, fucose, or sucrose; or chemotaxis toward glucose, galactose, xylose, or arabinose.

ATP-Binding Cassette Transporters↗
PubMed1997

Histomorphometric assessment of bone mass, structure, and remodeling: a comparison between healthy black and white premenopausal women.

While noninvasive studies of bone mass and turnover in blacks and whites abound, histologic evaluations are very rare. We have performed a comparative bone histomorphometric study of iliac biopsies from 55 healthy, premenopausal women including 21 blacks (mean age 33.4 + 1.2 years) and 34 whites (mean age 32.5 + 0.8 years) of comparable age, weight, body composition, education, and lifestyle. Biochemical indices of mineral metabolism: parathyroid hormone, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, serum ionized calcium, serum phosphorus, and urinary calcium/creatinine were measured in the fasting state. Blacks had lower 25-hydroxyvitamin D (315 +/- 3.36 vs. 63.21 +/- 3.79 nmol/l, p = 0.0001). Histomorphometric indices of bone volume, structure, and connectivity were not different between groups. The following indices of bone remodeling were also similar in both groups: eroded perimeter, osteoid width, mineralizing perimeter, tissue-based bone formation rate, osteoid maturation time, active formation period, and activation frequency. However, osteoid perimeter (black [B] = 15.85 +/- 1.30 vs. white [W] = 9.49 +/- 0.70%, p = 0.0002), osteoid area (B = 2.55 +/- 0.32 vs. W = 1.39 +/- 0.12%, p = 0.003), single-labeled perimeter (B = 5.46 +/- 0.54 vs. W = 4.04 +/- 0.33%, p = 0.03), mineralization lag time (B = 38.18 +/- 4.04 vs. W = 21.83 +/- 1.60 days, p < 0.009), and total formation period (B = 148.15 +/- 19.70 vs. W = 84.04 +/- 7.62 days, p = 0.0056) were higher in blacks than in whites. The quiescent perimeter (B = 76.91 +/- 1.40 vs. W = 84.25 +/- 0.91%, p = 0.0001), mineral apposition rate (B = 0.70 +/- 0.02 vs. W = 0.75 +/- 0.02 micron/day, p = 0.066), mineralizing osteoid perimeter (B = 0.49 +/- 0.04 vs. W = 0.75 +/- 0.04%, p = 0.0001) and adjusted apposition rate (B = 0.35 +/- 0.04 vs. W = 0.58 +/- 0.04 micron3/micron2/day, p = 0.0001) were all lower in blacks than in whites. These results indicate that there are no differences in bone volume, microstructure, or turnover between black and white premenopausal women. However, there are significant differences in the mechanism of bone formation between the two groups, with a lower rate of mineralized matrix apposition within each remodeling unit and a longer total formation period in blacks than in whites. The differences appear to the result of more frequent and/or longer inactive periods in the life span of the bone formation units in blacks. These differences may allow a greater overall deposition of bone mineral in black women and therefore help explain a higher bone mass and perhaps better bone quality in black than white women.

Adult↗
PubMed1997

[The relationship between prognosis, metastasis and microvessel quantity in invasive breast carcinoma].

OBJECTIVE: To determine the prognostic value and relationship of microvessel quantity (MVQ) with PCNA, c-erbB-2, nm23-H1 and Cathepsin D in invasive breast carcinoma. METHODS: Immunohistochemical techniques (LSAB) were used to detect the expression of PCNA, c-erbB-2, nm23-H1, Cathepsin D and MVQ in 76 cases of invasive breast carcinoma. RESULTS: The mean of MVQ was 57.82 +/- 22.22 in 76 cases of invasive breast carcinoma. The expression of Cathepsin D (cancer cells), c-erbB-2 and node positive were not related to MVQ. MVQ was positively correlated to expression of Cathepsin D (stroma cells), PCNA and distant metastasis (10 years), but negatively correlated to 5 year survival. CONCLUSION: MVQ was significantly correlated to distant metastasis and survival period in invasive breast carcinoma. MVQ may be an independant prognostic indicator.

Adult↗
PubMed1997

[Study on the relationship between PS2 protein expression and prognosis in invasive breast carcinoma].

OBJECTIVE: To study the relationship between the expression of PS2 protein and prognosis in the invasive breast cancer (IBC). METHOD: Using LSAB immunohistochemical method, PS2 protein expression in 86 cases of IBC was detected. RESULTS: The positive rate of PS2 protein was 66.27% (57/86) in 86 cases of IBC. Under the following 3 conditions, PS2 protein expression levels in the more-than-5-year-survival group (A) were higher than those in the less-than-5-year-survival group (B). (1) In 86 cases of IBC, the expression level was 80.55% (29/36) for Group A, Significantly different from the 56.00% (28/50) of Group B (P < 0.025). (2) In 62 cases of premenopausal patients, the corresponding data were 86.20% (25/29) and 54.54% (18/33) respectively, P < 0.005; whereas in 24 cases of postmenopausal patients, 4/7 and 58.82% (10/17) respectively, P > 0.5. (3) In 62 cases of axillary node positive patients, the expression levels for Groups A and B were 82.35% (14/17) and 55.55% (25/45) respectively, P < 0.05; while in 24 cases of axillary node negative patients, 78.94% (15/19) and (3/5) respectively, P > 0.5. CONCLUSIONS: These results suggest that the expression of PS2 protein was positively correlated with 5-year-survival in IBC, and could be considered as a prognostic predictor for breast cancer, PS2 protein expression was a useful indicator for endocrine therapy in premenopausal patients. In axillary node positive patients, the expression of PS2 protein was associated with a better prognosis.

Adult↗
PubMed1997

[An experimental study on tissue renin-angiotensin-aldosterone system].

Aldosterone biosynthesis in kidney has been proved by means of kidney perfusion in vitro, high performance liquid chromatography, radioimmunoassay and TR-PCR, indicating that aldosterone biosynthesis is possible in tissues other than adrenal. Bilateral nephrectomy was carried out in male Wistar rats and the plasma renin activity would disappear after 30 hours. However, RT-PCR showed that the vasculature in the nephrectomized rats was still able to express renin mRNA. It means that the vasculature is different from the heart which depends on taking up renin from the circulation, while the vasculature takes renin produced locally in its own tissue to initiate the renin-angiotensin-aldosterone system. Perindopril, an angiotensin converting enzyme inhibitor (ACEI), inhibits not only the production of angiotensin II, but also the synthesis of aldosterone in the vasculature. ACEI reversion of vascular remodeling is probably related with its inhibition of aldosterone synthesis in the vasculature.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[The influence of porcelain thickness and non-uniformity on porcelain cracks in implant-supported metal-porcelain fixed bridge].

This experiment studied the influence of porcelain thickness and non-uniformity on porcelain crack in implant-supported metal-porcelain fixed bridge. The result indicated that porcelain crack began to appear when the body porcelain powder was 3-5 mm in thickness; more cracks took place when the powder thickness increased by 1 mm to 2 mm on the axial surface in the axial direction; cracks became serious when the thickness suddenly changed to zero; and connectors were liable to cracks. Therefore, in designing and fabrication, one should avoid and sudden change in the shapes of the connector and the porcelain on it, any sudden change in the thickness of porcelain and a thickness of porcelain powder not less than 3.5 mm. Other-wise, it is neccessary to use internal crown between metal base and abutment to meet the demands.

Dental Porcelain↗
PubMed1997

[Experimental study on fitness of retainers of one-piece casting frameworks of distal-extension implant denture].

An experiment on fitness of retainers of one-piece casting frameworks was performed between two non-noble metals and among three of abutment positions fixture implant with a coordinate measuring machine for three-dimensional analysis. The results showed that there was no statistically significant differences in retainer fitness between the two metals, and among the three fixture abutment positions. However, all retainer displayed shrinkage in three dimensions, and the retainer shrinkage on the cervical surface were more than on the occlusal surface. The fitness of retainers of one-piece casting frameworks would be improved if used in multi-unit implant fixed denture.

Chromium Alloys↗
PubMed1997

[Study on red cell enzymes and isoenzymes in patients with leukemia and myelodysplastic syndromes].

OBJECTIVE: To define the prevalence of acquired red cell enzymopathy in leukemia and MDS patients and explore its clinical significance. METHODS: Red cell enzymes (G6PD, 6PGD, PK, ENOL, ADA, PNP,ALD) activities and PK,ADA isoenzymes were assayed by the methods recommended by ICSH and PAGE electrophoresis. RESULTS: The prevalence rate of G6PD deficiency was 43.1%, and of PK deficiency was 27.8%, in leukemia and MDS patients. The prevalence rates of PK, G6PD and PNP deficiency in MDS patients were 50%, 48% and 39.1%, respectively, while of ADA, ENOL and ALD over production in MDS patients were 69. 6%, 40% and 30. 4%, respectively. PK activity was increased in CML, while the PK isoenzyme pattern was normal. Administration of antitumor antibiotics to AL decreased G6PD and 6PGD activities (P < 0.05). ADA2 was expressed in MNC of AML (M4 and M5) and in RBC of CMML, but not expressed in ALL (P < 0.001). CONCLUSION: Determination of enzymes may be used as prognostic parameters in CML,a predictor of antitumor drug resistance in acute leukemia, and a differential parameter between MDS-RA and aplastic anemia and between CML and CMML.

Adolescent↗
PubMed1997

[The determination of enantiomeric purity for 1,1'-binaphthyl-2,2'-diol by high performance liquid chromatography].

In the past few years, much attention has been focused on the studies of the chirality recognition properties of chiral crown ether hosts containing the binaphthyl unit. The application of chiral 1,1'-binaphthyl-2,2'-diol (1) in asymmetric synthesis has been proved fruitful. Consequently, the preparation of optically active binaphthol and the determination of its enantiomeric purity is of current interest. In this paper, an efficient HPLC method for determination of enantiomeric purity of 1,1'-binaphthyl-2,2'-diol (1) through formation of a couple of diastereomers, (R)-1,1'-binaphthyl-2,2'-diyl-N-(S)-(alpha-methylbenzyl) phosphoramidate (R,S)-2 and (S)-1,1'-binaphthyl-2,2'-diyl-N-(S)-(alpha-methylbenzyl)phosphoramidate (S,S)-2, is described by using Micropak Si-5 column, petroleum and ethanol (7:3, V/V) as eluate and UV detector (lambda = 300nm). The method is convenient, rapid and accurate. The accuracy was between 98.6%-101.6%, and the average deviation was 1.01%.

Chromatography, High Pressure Liquid↗