Biomedical subjects

J Yao

Publications and source records attributed to J Yao.

At least 217 records · Page 12Linked to original sources

PubMed1997

Suppression of osteoblast function by titanium particles.

In order to understand the effect of particulate debris on osteoblast function, we studied the effect of different particles, including titanium and polystyrene, on bone collagen mRNA (messenger RNA) with the use of Northern blot hybridization analysis, and we studied the effect of the particles on the biosynthesis of bone collagen with analysis of 3H-proline incorporation and with the Western blot technique. The steady-state levels of mRNA for procollagens alpha1(I) and alpha1(III) were markedly suppressed in human MG-63 osteoblast-like cells exposed to phagocytosable titanium particles that were smaller than three micrometers. Both titanium and polystyrene particles smaller than three micrometers suppressed the expression of the gene that codes for collagen, and the suppression of the expression of the gene was related to the size but not to the composition of the particles. The biosynthesis of both type-I and type-III collagen also was decreased in cells that had been treated with titanium particles. Neither the viability nor the proliferation of cells was affected by particulate debris. These data indicate that phagocytosable titanium particles can significantly suppress the expression of the gene that codes for collagen in osteoblast-like cells (p < 0.05).

Blotting, Northern↗

PubMed1997

[Promotive effect of TNF-alpha and M-CSF on osteolysis induced by giant cell tumor of bone].

OBJECTIVE: To explore the effect of cell components in giant cell tumor of bone (GCT) and cytokines expressed by them on osteolysis. METHODS: Mononuclear stromal cells and multinucleated giant cells (MGCs) were isolated from 10 cases of GCT, and fibroblast-like stromal cells were obtained by long-term culture of mononuclear stromal cells. Osteolytic capability of above isolated cells were tested in an in vitro cell-bone resorption model. RESULTS: All cell components isolated from GCT had capability to resorb bone matrix directly. Exogenous tumore necrosis factor-alpha (TNF-alpha) could significantly increase the bone resorption induced by both kinds of stromal cell. There were higher level of TNF-alpha and greater expression rate of macrophage colony stimulating factor (M-CSF) in GCT than in the osteosarcoma tissues or the normal serum. CONCLUSIONS: The characteristic bone resorption behavior of GCT might be conducted by all it's three major cell components, and this bone resorption process could be promoted by both TNF-alpha and M-CSF they expressed.

Bone Neoplasms↗

PubMed1997

[Research on the relation between the biting force with complete denture and compression of the mandibular denture bearing mucosa].

This experiment was designed to study the relation between the biting force and compression mucosal recovery and recovering time of the denture bearing mucosa with ten edentulous patients by the occlusometer and the photoelectric movement transducer. The results showed that the favourable threshold of biting force for denture bearing mucosa was 1.3 kg in anterior tooth region and 2.5 kg in molar region, up to 30 minutes after removal of biting force, the mucosal thickness was still 0.20 mm in anterior tooth region and 0.11 mm in molar region. According to these characteristics of the denture bearing mucosal compression and recovery, masticatory force of the complete dentures should be limited below above mentioned threshold.

Aged↗

PubMed1997

[The cloning and sequence analysis of cDNA of the partial E genomic region of Dengue type 4 virus from a Chinese patient].

The partial envelope (E) protein gene of Dengue virus type 4 (DV4), derived from the serum of a patient with dengue fever in an epidemic during October 1993 in Guangdong Province of China, was cloned and sequenced. DV RNA was converted to cDNA by reverse transcription with random primers before the polymerase chain reaction using DV4 specific primers was performed. The amplified product of 421bp was subsequently filled in 3' recessed ends, isolated, purified and inserted into pUC18 and pUC19 plasmid vector. Their sequences were determined by dideoxy nucleotide chain termination method. A comparison between DV4 Chinese strain and several other previously reported strains shows the homology to be 93.72% for the same dengue serotype, 61.26-64.40% for the other dengue serotypes, only 40.31% for Japanese encephalitis virus, which belongs to the member of flavivirus family. A conserved sequence with 12 amino acids observed from deduced protein sequence probably represents an essential functional element among flavivirus family.

Amino Acid Sequence↗

PubMed1997

Acute and chronic response to vanadium following two methods of streptozotocin-diabetes induction.

Controversial reports on the efficacy and possible toxicity of vanadium obtained from various studies may be attributed to differences in the method of diabetes induction and (or) to differences in animal strains. The objective of this study was to evaluate the contribution of these two factors to the effects of vanadium in the treatment of experimental diabetes. Two methods of streptozotocin induction of diabetes in rats have been used for studying the antidiabetic effects of vanadium. One involves a single intravenous injection of 60 mg/kg streptozotocin, and the other uses two subcutaneous injections of 40 mg/kg streptozotocin, to either Wistar or Sprague-Dawley rats. In a 7-week chronic study, Sprague-Dawley rats appeared to develop a more severe diabetes (indicated by higher plasma cholesterol and higher fasting plasma glucose levels) following the single intravenous injection of streptozotocin than rats made diabetic by two subcutaneous injections of streptozotocin. Irrespective of the method of diabetes induction, the responses of all the diabetic animals to chronic vanadyl sulphate treatment were similar. In an acute study, Wistar diabetic rats were more responsive than Sprague-Dawley diabetic rats to vanadyl sulphate and to lower doses (0.6 and 0.8 mmol/kg) of a new organic vanadium compound, bis(maltolato)oxovanadium(i.v.).

Animals↗

PubMed1997

Sp family members preferentially interact with the promoter proximal repeat within the HTLV-I enhancer.

Human T cell lymphotropic virus type I (HTLV-I) encodes the transactivator protein, Tax, which facilitates viral transcription from three 21 bp repeated elements within the U3 region of the long terminal repeat (LTR). Examination of the basal factors interacting with the 21 bp repeat elements through electrophoretic mobility shift (EMS) analyses has demonstrated the formation of DNA-protein complexes common to each of the 21 bp repeats (C1-C3) as well as three DNA-protein complexes specific to the promoter proximal (pp) repeat (U1 (U1A/U1B) and U2; 1-4). These studies have indicated that the individual repeats are not identical with respect to the cellular factors with which they interact. EMS analyses utilizing a series of mutated pp repeat elements demonstrate that the nucleotide sequence requirements for U1 (U1A/U1B) and U2 formation are separable from those required for C1-C3 formation. Competition EMS analyses utilizing Sp1 and CREB binding site oligonucleotides demonstrate that Sp family members are critical components of U1 (U1A/U1B) and U2 and that ATF/CREB family members are critical components of C1-C3. EMS supershift analyses have demonstrated that Sp1 is involved in U1A formation while Sp3 is involved in U1B and U2 formation. EMS analyses performed with nuclear extracts from Tax-expressing Jurkat cells and HTLV-I-transformed peripheral blood mononuclear cells demonstrate that Tax prevents the formation of U1 (U1A/U1B) and U2 DNA-protein complexes. Therefore, Tax appears to inhibit the interaction of Sp family members with the pp repeat. Based on these observations, it is possible that the interaction of Sp and ATF/CREB family members with the pp repeat during basal and Tax-mediated transcription may play a critical role in viral gene expression during the initial stages of virus infection or during activation of a latent infection.

Base Sequence↗

PubMed1997

[Embryotoxic factors and recurrent spontaneous abortions].

About 30% of recurrent spontaneous abortions remain unexplained by traditional or biological anomalies. The purpose of this work was to investigate embryotoxic factors produced by trophoblast stimulated lymphocytes from women with unexplained recurrent spontaneous abortion. The samples from 36 women with recurrent abortion before and during the next pregnancy and from 7 women with normal pregnancies and no history of spontaneous abortion have been tested. The lymphocytes were stimulated with trophoblastic extracts. The supernatants of the stimulated lymphocytes were tested in a 4-cell mouse embryo culture. The secretion of embryotoxic factor was determined if the number of life blastocysts was less than 50% of control values after 4 days. The lymphocytes from 59% women with 3 or more recurrent abortion produced the embryotoxic factor, this factor may be useful in predicting pregnancy outcome in women with a history of unexplained recurrent miscarriage. The embryotoxic factor might be a new cause of recurrent abortion and a predictive factor.

Abortion, Habitual↗

PubMed1997

[Experimental treatment of rhubarb on mesangio-proliferative glomerulonephritis in rats].

Accumulation of extracellular matrix is a prominent feature of progressive glomerulonephritis (GN). Previously, we have shown that Emodin, an important component of Rhubarb, inhibits the fibronectin (FN) production of cultured mesangial cells. We now provide evidence of the same effect of Rhubarb in immune complex GN induced in rats by injection of anti-thymocyte serum (ATS). Rhubarb ameliorated mesangial matrix expansion on day 7 after ATS administration. Decreased FN level and IL-1 activity were found in the supernatant of cultured glomeruli from Rhubarb-treated animal at the 7th day. Glomerular tissue FN fluorescence staining was also much weaker than that of the untreated rats. These studies demonstrated that Rhubarb-treated anti-Thy-1 animal model should develop significantly less matrix expansion. Rhubarb also inhibited synthesis and secretion of fibronectin, an important component of mesangial extracellular matrix. Decreased IL-1 activity might be involved in the therapeutic effect of Rhubarb on mesangioproliferative glomerulonephritis.

Animals↗

PubMed1996

Loss of lysosomal integrity caused by the decrease of proton translocation in methylene blue-mediated photosensitization.

Loss of lysosomal integrity is a critical event for killing tumor cells in the photodynamic therapy of cancers. To elucidate the mechanism of photodamage induced lysosomal disintegration, we investigated the role of losing lysosomal proton translocation in latency loss of photosensitized lysosomes. Isolated rat liver lysosomes were light exposed in the presence of Methylene blue. Through monitoring lysosomal delta pH with Acridine orange and measuring its membrane potential with 3,3'-dipropylthiadicarbocyanine iodide, loss of Mg-ATP dependent proton translocation and decrease in electrogenicity of the proton pump were observed after lysosomes were photosensitized. When normal lysosomes were incubated for 60 min in K+ contained medium, percentage free activity of lysosomal enzyme beta-galactosidase increased, i.e. lysosomal latency decreased. In the presence of Mg-ATP, the latency loss of incubated lysosomes reduced. Addition of n-ethylmaleimide, a potent inhibitor of lysosomal H(+)-ATPase, abolished the effect of Mg-ATP on lysosomal latency. It suggests a role of proton translocation in protecting lysosomal integrity. Under the same conditions, Methylene blue photosensitized lysosomes increasingly lost latency of beta-hexosaminidase and beta-galactosidase with light exposure, presumably due to the photodamage induced loss of proton pumping. In contrast, the photosensitization did not decrease lysosomal latency in the absence of Mg-ATP, implying that lysosomal integrity might not be impaired via other photodamage effects under the conditions of this study. These results indicate that lysosomal integrity can be photodestructed via the loss of proton translocation.

Animals↗

PubMed1996

Chondrocyte matrix metalloproteinase-8. Human articular chondrocytes express neutrophil collagenase.

This study confirms that normal human articular chondrocytes express neutrophil collagenase or matrix metalloproteinase-8 (MMP-8), a gene product previously thought to be expressed exclusively by neutrophil leukocytes. Both MMP-8 protein and mRNA were present in articular cartilages collected from normal human donors. Cartilage extracts were assayed by immunoblotting and by analysis of enzymatic activity on gelatin-substrate gels. Latent MMP-8 extracted from cartilage has a molecular mass of 55 kDa; active MMP-8 was identified at 46 and 42 kDa. In the absence of a reducing agent, MMP-8 migrated in a high molecular mass complex above 200 kDa. Northern blotting results demonstrated the expression of MMP-8 in chondrocytes, which could be up-regulated by stimulation with interleukin-1 beta. In addition, reverse transcription-polymerase chain reaction using nested primers and in situ hybridization revealed the presence of MMP-8 mRNA in chondrocytes. The presence of both MMP-8 protein and message in cartilage supports the concept that neutrophil collagenase could be the enzyme described as "aggrecanase".

Blotting, Northern↗

PubMed1996

Dopamine turnover in schizophrenia before and after haloperidol withdrawal. CSF, plasma, and urine studies.

The dopamine hypotheses of schizophrenia and antipsychotic drug action suggest that the dopamine metabolite homovanillic acid (HVA) should change with drug withdrawal and change in clinical state. We designed a study of cerebrospinal fluid (CSF), plasma, and urinary HVA on and off haloperidol to examine the effects of drug withdrawal. CSF and plasma HVA samples were obtained in 72 healthy schizophrenic (DSM-III-R) males (age: 36 +/- 7.4 years), before and after haloperidol withdrawal, which was after 6 weeks on placebo or sooner if they met specific criteria for relapse. We collected three 24-hour urine samples in 34 of these patients. In addition, CSF HVA was obtained in 24 well-screened age-matched male normal controls. HVA was measured with high-pressure liquid chromatography (HPLC). CSF HVA decreased significantly after drug withdrawal, particularly in those who met relapse criteria; drug-free CSF HVA levels were not significantly different from those of normals. Plasma HVA increased significantly after haloperidol withdrawal in relapsing patients, but not in clinically stable patients. Urinary HVA excretion decreased after withdrawal with decreased HVA clearance. We conclude that haloperidol withdrawal had a strong effect on dopamine turnover, whereas the patient's clinical state had only a weak central effect, without affecting total body production of HVA. Conceivably, dopamine involvement in schizophrenia reflects the failure of the homeostatic mechanisms that allow for integration of different functional brain components as needed.

Adult↗

PubMed1996

Dietary polyunsaturated fatty acid prevents malformations in offspring of diabetic rats.

OBJECTIVE: The purpose of the current study was to determine whether a dietary source of arachidonic acid could serve as a pharmacologic prophylaxis to obviate the teratogenic effects of hyperglycemia. STUDY DESIGN: Eighty-day-old Sprague-Dawley rats were mated, and after conception were randomly allocated to five groups: two groups were nondiabetic normal controls and three groups had diabetes experimentally induced with streptozocin. Of the two control groups, one was fed a normal diet (group 1) and the other group (group 2) received a normal diet and 1.0 ml of safflower oil, a polyunsaturated fatty acid known to increase serum arachidonic acid levels. In the three diabetic groups (groups 3, 4, and 5) glucose levels were allowed to remain > 350 mg/dl by withholding daily insulin therapy. Group 3 received a normal diet without supplementation; group 4 received a normal diet plus normal saline solution sham feedings, whereas group 5 received a normal diet supplemented with 1.0 ml of safflower oil. The oral agents (normal saline solution and polyunsaturated fatty acid) were administered with a tuberculin syringe. RESULTS: Diabetic rats not receiving insulin therapy and receiving normal diets produced offspring with malformation rates of 20% compared with control rates of 4.8%. Supplemental normal saline solution or safflower oil given orally to controls did not alter the growth or malformation rates. These rates were similarly unaffected in the diabetic rats receiving oral supplementation of normal saline solution. However, with safflower oil supplementation to diabetic rats the incidence of neural tube defects was decreased from 20.0% to 7.6% (p < 0.0001). An inverse relationship was observed between the malformation rate and the serum arachidonic acid level: 17.83 (SD 5.84 micrograms/ml) in the nondiabetic controls, with a malformation rate of 4.8%, versus 14.18 (SD 2.58 micrograms/ml) in the diabetic rats, with a malformation rate of 20.0% (p < 0.05). With safflower oil supplementation serum levels of arachidonic increased from 14.18 +/- 2.58 micrograms/ml to 19.99 +/- 7.99 micrograms/ml (p < 0.05); this was associated with a concomitant decline in the malformation rate. CONCLUSION: These data demonstrate that diabetic embryopathy is associated with a deficiency state in essential fatty acid, corroborating our previous in vitro findings. Furthermore, the use of a dietary polyunsaturated fatty acid that specifically increases arachidonic levels significantly reduced the incidence of diabetic embryopathy. These findings may serve as a basis for developing strategies of pharmacologic prophylaxis against diabetes-induced congenital malformations.

Animals↗

PubMed1996

"Sero-switch" adenovirus-mediated in vivo gene transfer: circumvention of anti-adenovirus humoral immune defenses against repeat adenovirus vector administration by changing the adenovirus serotype.

Recombinant, replication-deficient adenovirus (Ad) vectors have been successfully used to transfer and express the normal human cystic fibrosis transmembrane conductance regulator (CFTR) cDNA in vivo in the respiratory epithelium of experimental animals and humans with cystic fibrosis (CF). Since Ad-directed gene expression wanes over time, repeat administration is necessary to achieve an effective treatment for CF. A major hurdle to such a strategy is the possibility that anti-Ad humoral immunity may prevent gene expression in individuals with pre-existing anti-Ad immunity or following repeat administration. One strategy to circumvent such a problem would be alternating the use of Ad vectors belonging to different subgroups. Neutralizing antibodies developed with the administration of one Ad serotype do not cross-react with an Ad belonging to a second serotype in a manner that blocks infection and gene expression. To test this hypothesis, an immunizing dose of wild-type Ad5 (subgroup C), Ad4 (subgroup E), or Ad30 (subgroup D) was administered intratracheally to experimental animals, followed by an intratracheal administration of a replication-deficient subgroup C-derived vector coding for marker genes (chloramphenicol acetyl transferase or beta-galactosidase) or for the normal human CFTR cDNA. As expected, studies with vectors coding for marker genes or for CFTR cDNA demonstrated that airway administration of a vector does not yield efficient gene transfer, if there has been prior recent airway administration of the same Ad subgroup. In contrast, effective expression from the second administration can be achieved with an adenovirus vector belonging to a subgroup different from the first adenovirus administered. These data support the paradigm of alternating Ad vectors derived from different subgroups as strategy to circumvent anti-Ad humoral immunity, thus permitting the use of Ad vectors as a means to treat the respiratory manifestations of CF.

Adenoviruses, Human↗

PubMed1996

Sequence variations in the bovine growth hormone gene characterized by single-strand conformation polymorphism (SSCP) analysis and their association with milk production traits in Holsteins.

Sequence variations in the bovine growth hormone (GH) gene were investigated by single strand conformation polymorphism (SSCP) analysis of seven amplified fragments covering almost the entire gene (2.7 kb). SSCPs were detected in four of these fragments and a total of six polymorphisms were found in a sample of 128 Holstein bulls. Two polymorphisms, a T-->C transition in the third intron (designated GH4.1) and an A-->C transversion in the fifth exon (designated GH6.2), were shown to be associated with milk production traits. GH4.1c/GH4.1c bulls had higher milk yield than GH4.1c/GH4.1t (P < or = 0.005) and GH4.1t/GH4.1t (P < or = 0.0022) bulls. GH4.1c/GH4.1c bulls had higher kg fat (P < or = 0.0076) and protein (P < or = 0.0018) than GH4.1c/GH4.1t bulls. Similar effects on milk production traits with the GH6.2 polymorphism were observed with the GH6.2a allele being the favorable allele. The average effects of the gene substitution for GH4.1 and GH6.2 are similar, with +/-300 kg for milk yield, +/-8 kg for fat content and +/-7 kg for protein content per lactation. The positive association of GH4.1c and GH6.2a with milk production traits may be useful for improving milk performance in dairy cattle.

Animals↗

PubMed1996

A MspI polymorphism in the bovine ornithine decarboxylase gene and its possible association with selection for milk production in Holstein bulls.

A polymerase chain reaction (PCR)-based method for detection of a MspI-restriction fragment length polymorphism (RFLP) in the bovine ornithine decarboxylase gene was developed, and the allele frequencies of the polymorphism in two groups of Holstein bulls representing progeny-tested bulls during the 1950s-1960s and 1980s, respectively, were estimated. The frequencies of the MspI(-) allele ere 0.229 and 0.077 and that of MspI(+) were 0.771 and 0.923 in the progeny-tested bulls of the 1950s-1960s and 1980s, respectively. The difference in allele frequencies between the two groups was statistically significant (P < 0.005). Genetic drift could be responsible for the changes in allele frequencies; however, it could also be possible that selection for milk production was associated with the changes of the allele frequencies in the two bull populations.

Alleles↗

PubMed1996

Comparison of ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis for molecular typing of Listeria monocytogenes.

Fifty-one clinical isolates of Listeria monocytogenes (15 isolates from two outbreaks and 36 epidemiologically unrelated isolates) were typed by conventional serotyping, ribotyping (RT), pulsed-field gel electrophoresis (PFGE), and arbitrarily primed PCR (AP-PCR). Serotyping was unable to distinguish between related and unrelated strains of L. monocytogenes. Each of the three molecular methods showed excellent typeability and reproducibility. Restriction with EcoRI and PvuII gave 16 and 23 RT patterns, respectively. Restriction with ApaI or SmaI generated 22 and 26 PFGE profiles, respectively. ApaI profiles were easier to interpret, with 10 to 15 bands each, while SmaI profiles had 15 to 20 bands each. AP-PCR with two different primers yielded 29 and 31 randomly amplified polymorphic DNA patterns, respectively. Strains from the same outbreak shared concordant patterns by each of the three methods. Of the three techniques evaluated, RT was the least discriminating and could not distinguish between strains from the two outbreaks. The abilities of AP-PCR and PFGE to differentiate between strains were comparable. However, AP-PCR was more rapid and easier to perform. We conclude that the DNA profiles generated by either AP-PCR or PFGE can be used to differentiate outbreak strains from epidemiologically unrelated strains and to clearly identify unrelated strains as being distinct from one another. We recommend that at least two independent primers be used for AP-PCR typing in order to improve its discriminatory power.

Bacterial Typing Techniques↗

PubMed1996

Mesangial cell-matrix interactions in glomerular inflammation.

Specific interactions between cells and components of the surrounding extracellular matrix (ECM) or underlying basement membrane have been shown to modulate cell behaviour, in culluro and in vivo. There is evidence that extensive 'cross-talk' occurs between glomerular mesangial cells (MCs), ECM molecules, and soluble mediator substances affecting the proliferative and synthetic-secretory phenotype of MCs. This is likely to be relevant for the behaviour of MCs during embryonic development, disease processes of glomeruli, and tissue repair. The potential biologic and clinical relevance of cell-matrix interactions in the glomerulus are discussed in this brief review of selected aspects of recent investigations concerning the mesangial matrix and its interactions with MCs.

Animals↗

PubMed1996

Autocrine motility factor receptor as a possible urine marker for transitional cell carcinoma of the bladder.

PURPOSE: To determine whether autocrine motility factor receptor (AMFR) is detectable in the urine of patients with transitional cell carcinoma (TCC) of the bladder. MATERIALS AND METHODS: We assayed the urine of 89 patients with bladder pathology and 28 normal controls for AMFR. A monoclonal antibody to AMFR was used. RESULTS: All patients with muscle-invasive TCC tested positive for AMFR. Autocrine motility factor receptor was detectable for 80% of superficial tumors, with a correlation between AMFR and tumor grade. Seventy-five percent of control urines tested negative. CONCLUSIONS: Autocrine motility factor receptor is detectable in the urine of patients with TCC. Long-term follow-up and refinements in the assay should define the marker's utility for detection and prognosis.

Adult↗