Biomedical subjects

Z Ye

Publications and source records attributed to Z Ye.

At least 73 records · Page 4Linked to original sources

PubMed1999

[The effects of levothyroxine replacement therapy on bone and mineral metabolism in patients with hypothyroidism].

OBJECTIVE: To investigate the effects of short-term thyroid hormone replacement therapy on bone and mineral metabolism in patients with hypothyroidism. METHODS: Enzyme linked immunosorbent assay (ELISA) was used to measure urinary deoxypyridinoline (DPD) and radioimmunoassay (RIA) to measure serum calcitonin (CT), parathyroid hormone (PTH-M), bone GLA protein (BGP), free T(3) (FT(3)), free T(4) (FT(4)) and thyroid-stimulating hormone (TSH) in 29 patients with hypothyroidism before and after treatment with levothyroxine for (11.5 +/- 2.5) months. Dual energy X-ray absorptiometry was used to measure bone mineral density (BMD) of their spine (L(2 - 4)) and femur neck, trochanter and Ward's triangle. The results were compared with those in 37 healthy controls. RESULTS: In hypothyroidism patients before treatment, serum BGP level was significantly lower (P < 0.05) than but urinary DPD was similar with those of control. BMD was significantly lower in postmenopausal patients (P < 0.01 - 0.001) than that in control group, but there was no change in premenopausal patients. After replacement therapy serum BGP and urinary DPD elevated significantly (P < 0.05), whereas BMD decreased slightly both in the premenopausal and postmenopausal patients when compared with that before treatment, with no statistical significance (P > 0.05). BMD decreased by 0.7% and 1.7% - 5.1% in premenopausal and postmenopausal patients respectively, but there was no significant difference between these two groups (P > 0.05). FT(3) was positively correlated with BGP. FT(4) and FT(3) were positively correlated with DPD. BMD of femur neck and trochanter sites was negatively correlated with FT(4). CONCLUSION: Short-term physiological dose levothyroxine replacement therapy causes increase of bone turnover and leads to bone mass loss to various extent on hypothyroidism patients.

Adult↗

PubMed1999

[Cervical lymph node metastasis and blood metastasis of thyroid cancer].

OBJECTIVE: To evaluate the relevant factors for lymph cervical node metastases and blood metastases of thyroid cancer and to raise the level of diagnosis and treatment. METHODS: 225 cases of thyroid cancer were treated from Jan. 1984 to Dec. 1992. Their clinical characteristics, treatment, and pathologic features were described. RESULTS: The metastasis of thyroid cancer was related to its pathologic and invasive features. Papillary and squamous cell carcinomas were characterized by local lymph metastasis. Their metastasis rate was 44.7%, and 3/3 respectively. Follicular carcinoma showed good differentiation but vessel metastasis with a metastatic rate of 18.2%. The metastasis rate was high and the prognosis poor, in undifferentiated cancer. CONCLUSIONS: Better treatment results may be achieved if proper management of thyroid cancer is based on its pathologic type and extent of local infiltration.

Adenocarcinoma, Follicular↗

PubMed1999

[Synergistic interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines in vitro].

OBJECTIVE: To study in vitro the anticancer interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines. METHOD: Using human breast cancer cell MCF-7 and its adriamycin-resistant cell line MCF-7/Adr, and human nasopharyngeal cancer cell KB and its vincristine-resistant cell line KBv200 in an in vitro system, anticancer interaction between Ys-96 and adriamycin or vincristine was evaluated with a method reported by Berenbaum. RESULT: The SFIC values (sum of fractional inhibitory concentration) of the combinations with 3 different ratios between Ys-96 and adriamycin or vincristine were markedly less than 1.0, and the shapes of all the isobologram curves were concave. CONCLUSION: The synergistic interaction between Ys-96 and adriamycin or vincristine against the above human cancer cell lines was positively observed in vitro.

Antineoplastic Agents, Phytogenic↗

PubMed1999

[Analysis of mathematical model parameters for continuous rotary annular chromatography].

The curves of analysis solution of mathematical model for continuous rotary annular chromatography (CAC) coincide with experimental results well, but some points are derived from theoretical values due to the errors from experimental method. The width and the angles of maximum mass concentration solution at outlet (retention number), except for the other experimental conditions, depend on phase equilibrium coefficient and transfer functions. Because the precision of model parameters is strongly affected by the correction of experimental method, the sensitivities of phase equilibrium coefficients and transfer functions have been studied, in which the phase equilibrium coefficient is the key parameters to improve the separation effect of CAC process.

Biotechnology↗

PubMed1998

Insulin-degrading enzyme regulates extracellular levels of amyloid beta-protein by degradation.

Excessive cerebral accumulation of the 42-residue amyloid beta-protein (Abeta) is an early and invariant step in the pathogenesis of Alzheimer's disease. Many studies have examined the cellular production of Abeta from its membrane-bound precursor, including the role of the presenilin proteins therein, but almost nothing is known about how Abeta is degraded and cleared following its secretion. We previously screened neuronal and nonneuronal cell lines for the production of proteases capable of degrading naturally secreted Abeta under biologically relevant conditions and concentrations. The major such protease identified was a metalloprotease released particularly by a microglial cell line, BV-2. We have now purified and characterized the protease and find that it is indistinguishable from insulin-degrading enzyme (IDE), a thiol metalloendopeptidase that degrades small peptides such as insulin, glucagon, and atrial natriuretic peptide. Degradation of both endogenous and synthetic Abeta at picomolar to nanomolar concentrations was completely inhibited by the competitive IDE substrate, insulin, and by two other IDE inhibitors. Immunodepletion of conditioned medium with an IDE antibody removed its Abeta-degrading activity. IDE was present in BV-2 cytosol, as expected, but was also released into the medium by intact, healthy cells. To confirm the extracellular occurrence of IDE in vivo, we identified intact IDE in human cerebrospinal fluid of both normal and Alzheimer subjects. In addition to its ability to degrade Abeta, IDE activity was unexpectedly found be associated with a time-dependent oligomerization of synthetic Abeta at physiological levels in the conditioned media of cultured cells; this process, which may be initiated by IDE-generated proteolytic fragments of Abeta, was prevented by three different IDE inhibitors. We conclude that a principal protease capable of down-regulating the levels of secreted Abeta extracellularly is IDE.

Alzheimer Disease↗

PubMed1998

Structural requirements of human tissue factor pathway inhibitor (TFPI) and heparin for TFPI-heparin interaction.

Heparin affinity chromatography of synthetic peptide fragments mimicking tissue factor pathway inhibitor (TFPI) indicated that the minimal heparin binding sequence consists of 12 amino acid residues located at the C-terminal tail. Within this minimal sequence, Arg-257 and Arg-259 appeared to contribute most significantly to interaction with heparin. Affinity chromatography of TFPI using immobilized heparin derivatives regiospecifically desulfated at O-6 of the glucosamine residue, N-2 of the glucosamine residue, and/or O-2 of the iduronic acid residue indicated that all the sulfate groups in heparin appeared to be required for TFPI-heparin interaction. Among them, however, the 6-O-sulfate groups appeared to make the largest contribution to the interaction, while the 2-O-sulfate groups contributed the least. In vitro experiments on the inhibition of factor Xa by TFPI enhanced with native and chemically modified heparins afforded similar results.

Amino Acid Sequence↗

PubMed1998

Animal experimental study on surgical repair of hypospadias by free peritoneal graft.

Surgical repair of hypospadias was successfully performed by using free peritoneal graft in the model of rabbit hypospadias. The results showed that free peritoneal graft used as a substitute for urathra had a high survival rate, and the canal was formed well. Our study demonstrated that peritoneum could be used for the surgical repair of hypospadias and other urethral disorders such as urethral stricture.

Animals↗

PubMed1998

Testicular sperm extraction for nonobstructive azoospermia: results of a multibiopsy approach with optimized tissue dispersion.

OBJECTIVES: Testicular sperm extraction (TESE) is an effective procedure to retrieve sperm from some men with nonobstructive azoospermia (NOA). To optimize treatment effectiveness, we have reviewed our experience with TESE for NOA to better understand technical factors needed for sperm retrieval and lead to an optimized approach to TESE. METHODS: Eighty-one men with confirmed NOA underwent attempted TESE using an open technique under optical magnification. Each testis sample was dispersed and examined in the operating room. Sequential biopsy attempts were made until sperm were visualized or until further biopsies were thought to jeopardize testicular blood flow. In 20 patients, standard biopsy and initial mechanical dispersion of the seminiferous tubules were compared with the passage of tissue through a 24-gauge angiocatheter after initial dispersion to quantitate spermatozoal yield. RESULTS: Overall, 47 (58%) of 81 patients who underwent TESE had direct intraoperative visualization of spermatozoa. The average number of biopsy attempts for all patients was 8.9 and for patients with sperm isolated 6.4 (P = 0.002). Passage of the testicular tissue suspension through a 24-gauge angiocatheter increased sperm retrieval in matched tissue specimens from 83,000 to 390,000 or 470% over that achieved with standard dispersion alone (P = 0.005). An initial, substantive tissue biopsy revealed sperm in only 23 (28%) of 81 patients. Using this approach with sequential biopsies under optical magnification, no patient had evidence of testis injury or devascularization. CONCLUSIONS: Because multiple TESE procedures can cause transient and permanent alterations in testicular function, it is imperative to perform TESE as safely and as efficiently as possible. We suggest that open TESE with optical magnification provides a safe method of retrieving sperm. A single biopsy for extraction is inadequate to detect spermatozoa for men with NOA. Use of the needle dispersion technique with passage of testicular tissue through an angiocatheter enhances detection of sperm and could potentially reduce the need for subsequent biopsies. An algorithm to minimize biopsies and allow sperm retrieval is presented.

Adult↗

PubMed1998

Antiviral phenylpropanoid glycosides from the medicinal plant Markhamia lutea.

Three new phenylpropanoid glycosides, named luteoside A (3), luteoside B (4), and luteoside C (5), were isolated together with the known compounds verbascoside (1) and isoverbascoside (2) from the roots of the medicinal plant Markhamia lutea. The structures of the new compounds were determined to be 1-O-(3, 4-dihydroxyphenyl)ethyl beta-D-apiofuranosyl(1-->2)-alpha-l-rhamnopyranosyl(1-->3)-4-O- caffeo yl-6-acetyl-beta-d-glucopyranoside, 1-O-(3,4-dihydroxyphenyl)ethyl beta-d-apiofuranosyl(1-->2)-alpha-l-rhamnopyranosyl(1-->3)-6-O- caffeo yl-beta-d-glucopyranoside, and 1-O-(3,4-dihydroxyphenyl)ethyl beta-D-apiofuranosyl(1-->2)-alpha-l-rhamnopyranosyl(1-->3)-6-O- ferulo yl-beta-d-glucopyranoside, respectively, on the basis of chemical and spectroscopic data. All five phenylpropanoid glycosides exhibited potent in vitro activity against respiratory syncytial virus.

Antiviral Agents↗

PubMed1998

New iridoids from the medicinal plant Barleria prionitis with potent activity against respiratory syncytial virus.

Two new iridoid glycosides (1 and 2), together with the known compounds barlerin (3) and verbascoside (4), were isolated from Barleria prionitis. The new iridoid glycosides were determined to be 6-O-trans-p-coumaroyl-8-O-acetylshanzhiside methyl ester (1) and its cis isomer (2) by using spectroscopic, especially 2D NMR, data. A 3:1 mixture of 1 and 2 was shown to have potent in vitro activity against respiratory syncytial virus (EC50 2.46 microgram/mL, IC50 42.2 microgram/mL).

Antiviral Agents↗

PubMed1998

AZFb deletions predict the absence of spermatozoa with testicular sperm extraction: preliminary report of a prognostic genetic test.

Genetic abnormalities, including partial deletions of the Y-chromosome, are commonly detectable in men with non-obstructive azoospermia (NOA). NOA can be treated using testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI). Recent studies have shown that the presence of deletions involving the AZFc region do not appear to affect the chance of retrieving spermatozoa or have a significant impact on fertilization or pregnancy rates with ICSI. We investigated the effect of Y-chromosome partial deletions on the chance of sperm retrieval with TESE. Eighty attempts at sperm retrieval were performed using TESE on men who were previously evaluated for Y-chromosome partial deletions. Y-chromosome analysis was performed using a polymerase chain reaction (PCR)-based technique with 35 sequence-tagged-sites. Of the 80 men, nine (11%) had partial Y-chromosome deletions detected. Two azoospermic men with AZFc deletions had successful sperm retrieval, ICSI and a subsequent clinical pregnancy. Seven men had deletions involving the AZFb region (three men had isolated AZFb deletions, one had AZFa, AZFb and AZFc deleted, and three had AZFb and AZFc deleted). None of the seven men had spermatozoa extracted by TESE, a result that is significantly different from the overall 64% (47/73) sperm retrieval rate achieved at our centre (P = 0.001). Two men with AZFb deletions had cells consistent with round spermatids identified and injected into oocytes without effecting any normal fertilizations. Although preliminary, these results suggest that the presence of an AZFb deletion is a significantly adverse prognostic finding for TESE. Men with AZFb deletions should be apprised of these results before attempting TESE-ICSI. Alternatives such as donor insemination or adoption should be considered or therapy delayed until improved results with round spermatid injections are likely.

Adult↗

PubMed1998

Controlled comparison of percutaneous and microsurgical sperm retrieval in men with obstructive azoospermia.

A controlled comparison of the efficacy and reliability of sperm retrieval by testicular fine needle aspiration (TFNA), percutaneous testicular needle biopsy (PercBiopsy) and microsurgical epididymal sperm aspiration (MESA) was performed in nine patients with obstructive azoospermia. During a planned MESA procedure, sperm retrieval was attempted on the same testis with TFNA and PercBiopsy. Spermatozoa were obtained from all patients using MESA and PercBiopsy. Spermatozoa were retrieved using TFNA from 6/9 (67%) men. The mean number of epididymal spermatozoa retrieved with MESA (15 x 106) was significantly higher (P = 0.003) than that retrieved percutaneously from the testis. The mean number of spermatozoa obtained by PercBiopsy was 0.116 x 10(6) while TFNA recovered 0.014 x 106 spermatozoa (P = 0.025). MESA is the optimal choice to retrieve the greatest number of spermatozoa with highest motility for assisted reproduction and subsequent cryopreservation. However, percutaneous testicular retrieval does not require microsurgical expertise and is less invasive. Our results suggest that the optimal percutaneous procedure for sperm retrieval from the testis involves percutaneous testicular needle biopsy with an automatic biopsy gun.

Adult↗

PubMed1998

Analysis of the distribution of cutaneous perforators in cutaneous flaps.

An anatomic and statistical analysis was performed on the distribution of cutaneous perforators that perfuse the scapular, radial forearm, and lateral arm cutaneous flaps. Perforators were categorized as direct, terminal, and intransitive, depending upon perforator origin and termination site relative to the source artery. Statistical cluster analysis of perforator distributions was performed to determine the regions in which cutaneous perforators are consistently found. The scapular and radial forearm flaps could be divided into up to three well-perfused segments. The analysis predicted the possibility of dividing the lateral arm flap into as many as seven segments while maintaining perfusion. Clinical applications of this method for preoperative flap design and elevation as well as final results are shown.

Arm↗

PubMed1998

[Changes of bone and mineral metabolism in patients with hyperthyroidism before and after treatment].

OBJECTIVE: To investigate the changes of bone and mineral metabolism in patients with hyperthyroidism before and after treatment. METHODS: Enzyme linked immunosorbent assay was used to measure bone-specific alkaline phosphatase (BAP) and deoxypyridinoline (DPD); radioimmunoassay to to measure serum calcitonin (CT), parathyroid hormone (PTH-M), bone GLA protein (BGP) and other markers related to bone metabolism; dual energy X-ray absorptiometry to measure bone mineral density (BMD) of spine(L2-4) and femur(Neck, Troch, Ward's) in 45 patients with hyperthyroidism before and after treatment and 58 healthy volunteers. RESULTS: The urinary DPD level was elevated by 527% in patients with hyperthyroidism before treatment. Compared to controls the serum ALP, BAP, BGP elevated by 62%, 146%, 87% (P < 0.001), BMD decreased to various extent, and women L2-4, Ward's were marked (P < 0.05). The results after treatment and before treatment showed that urinary DPD decreased by 79%; serum ALP, BAP, BGP decreased by 19.5%, 24.7%, 27.5% respectively (P < 0.001, 0.05, 0.05, > 0.05). All sites BMD increased, and women Troch sites were marked (P < 0.05). The correlation analysis showed that the urinary DPD was positively correlated with serum BGP(r = 0.349 P < 0.05). FT4 was positively correlated with BAP, ALP and DPD respectively) (r = 0.353, P < 0.05, r = 0.294 P = 0.05, r = 0.426 P < 0.01). CONCLUSION: Hyperthyroidism bone disease is caused by excessive serum thyroid hormone that speeds up bone turnover and marked bone absorption compared to bone formation.

Adult↗

PubMed1998

[Verification of a new processing technology for pilot production of Aconitum coreanum (Lévl.) Raipaics].

The stability and feasibility of a new technology for processing Aconitum coreanum have been tested for pilot production by determining the components, toxicity(LD50) and traditional identification standard. The result shows that the contents of guanfu A and total alkaloid between the small trial and pilot production are slightly different and LD50 are nearly similar. Hypaconitine was not found in all kinds of processed products. The new technology has thus been proved stable and feasible.

Alkaloids↗

PubMed1998

[Reversal effect of Ys-96, a bisbenzylisoquinoline, on adriamycin or vincristine resistance in human cancer cells in vitro].

OBJECTIVE: Reversal effect of Ys-96, a bisbenzylisoquinoline, on the resistance of human cancer cells to adriamycin or vincristine was studied in vitro. METHOD: In an in vitro culture system of human cancer cells MCF-7 and its adriamycin-resistant line MCF-7/Ad or KB and its vincristine-resistant line KBv200, the sensitivity(IC50) of the resistant cell lines to adriamycin or vincristine was evaluated with a MTT assay. RESULT: IC50 value of adriamycin or vincristine in combination with Ys-96 at a concentration of 1.00 mumol/L against MCF-7/Ad or KBv200 was found to be close to that of adriamycin alone or vincristine alone against the sensitive cell line MCF-7 or KB. CONCLUSION: The drug resistance of MCF-7/Ad or KBv200 could be essentially reversed by Ys-96 at a concentration of 1.00 mumol/L.

Benzylisoquinolines↗

PubMed1997

Defective HIV-1 provirus encoding a multitarget-ribozyme inhibits accumulation of spliced and unspliced HIV-1 mRNAs, reduces infectivity of viral progeny, and protects the cells from pathogenesis.

A HeLa T4 cell line containing a defective human immunodeficiency virus type 1 (HIV-1) DNA (HD4) was isolated. After transactivation with Tat, the HD4 DNA was transcribed into a single 3.7-kb mRNA that encodes a chimeric CD4/Env protein and a multitarget-ribozyme directed against multiple sites within the gp120 coding region of HIV-1 RNA (Chen et al., 1992). Early steps in HIV infection such as entry, reverse transcription, and proviral DNA formation were not affected in HD4 cells, and HD4 was efficiently transactivated after either HIV-1 or HIV-2 infections. HIV-2, which lacks all of the HIV-1-specific ribozyme target sites, replicated to high levels in HD4 cells whereas HIV-1 replication was selectively inhibited. Despite a reduced accumulation of all HIV-1 transcripts, transactivation of HD4 was efficient. Surprisingly, the most abundant, multiply spliced mRNAs were reduced even though they lack all of the ribozyme target sites. These results strongly suggest that the ribozyme co-localizes with unspliced HIV-1 pre-mRNA and/or genomic HIV-1 RNA in the nucleus. Cleavage of these precursor RNAs explains the reduction of all spliced and unspliced HIV-1 RNAs. Cleavage of genomic RNA probably contributed to the three-fold reduction in the infectivity of viral progeny. Thus, the HD4 ribozyme RNA functioned as a ribozyme in the nucleus and as a mRNA for a chimeric CD4/Env protein in the cytoplasm. Its unusual large size for a ribozyme (3.7 kb) indicates that, in the future, other antiviral proteins, like negative transdominant mutant HIV-1 proteins, may also be encoded to increase its antiviral potential in a gene therapy approach.

CD4 Antigens↗

PubMed1997

Degradation of amyloid beta-protein by a metalloprotease secreted by microglia and other neural and non-neural cells.

Amyloid beta-protein (Abeta) is the major component of neuritic (amyloid) plaques in Alzheimer's disease, and its deposition is an early and constant event in the complex pathogenetic cascade of the disease. Although many studies have focused on the biosynthetic processing of the beta-amyloid precursor protein and on the production and polymerization of Abeta, understanding the degradation and clearance of Abeta has received very little attention. By incubating the conditioned medium of metabolically labeled Abeta-secreting cells with media of various cultured cell lines, we observed a time-dependent decrease in the amount of Abeta in the mixed media. The factor principally responsible for this decrease was a secreted metalloprotease released by both neural and non-neural cells. Among the cells examined, the microglial cell line, BV-2, produced the most Abeta-degrading activity. The protease was completely blocked by the metalloprotease inhibitor, 1,10-phenanthroline, and partially inhibited by EDTA, whereas inhibitors of other protease classes produced little or no inhibition. Substrate analysis suggests that the enzyme was a non-matrix metalloprotease. The protease cleaved both Abeta1-40 and Abeta1-42 peptides secreted by beta-amyloid precursor protein-transfected cells but failed to degrade low molecular weight oligomers of Abeta that form in the culture medium. Lipopolysaccharide, a stimulator of macrophages/microglia, activated BV-2 cells to increase their Abeta-degrading metalloprotease activity. We conclude that secreted Abeta1-40 and Abeta1-42 peptides are constitutively degraded by a metalloprotease released by microglia and other neural cells, providing a potential mechanism for the clearance of Abeta in brain tissue.

Amyloid beta-Peptides↗