Biomedical subjects

Y Qi

Publications and source records attributed to Y Qi.

At least 109 records · Page 6Linked to original sources

PubMed1998

Differentiation of a catecholaminergic CNS cell line modifies tyrosine hydroxylase transcriptional regulation.

Recently, a tyrosine hydroxylase (TH)-expressing CNS-derived cell line, CAD, was obtained that is capable of undergoing reversible morphological differentiation. The isolation of the CAD line allowed us to ask whether different DNA regulatory elements direct TH transcription when cells are growing and undifferentiated versus postmitotic and differentiated. To this end, we compared expression of a transiently transfected bacterial chloramphenicol acetyltransferase reporter gene under the transcriptional control of TH 5' flanking DNA in CAD cells grown in the presence and absence of serum. Mutational analysis indicates that CAD cells differently regulate TH transcription depending on their state of differentiation. In both states, the cyclic AMP response element and AP1 site each activate transcription. However, in undifferentiated cells, the dyad/E-box element represses expression by approximately 2.7-fold, whereas it modestly activates transcription in differentiated cells. The role of the dyad/ E-box as a repressor correlates well with the two- to threefold lower amount of endogenous TH protein present in the undifferentiated CAD cells. This study demonstrates the differential use of TH DNA regulatory elements in proliferating, undifferentiated and nonproliferating, differentiated immortalized neuronal cells.

Animals↗

PubMed1998

Role of Pho-P in transcriptional regulation of genes involved in cell wall anionic polymer biosynthesis in Bacillus subtilis.

tagA, tagD, and tuaA operons are responsible for the synthesis of cell wall anionic polymer, teichoic acid, and teichuronic acid, respectively, in Bacillus subtilis. Under phosphate starvation conditions, teichuronic acid is synthesized while teichoic acid synthesis is inhibited. Expression of these genes is controlled by PhoP-PhoR, a two-component system. It has been proposed that Pho-P plays a key role in the activation of tuaA and the repression of tagA and tagD. In this study, we demonstrated the role of Pho-P in the switch process from teichoic acid synthesis to teichuronic acid synthesis, by using an in vitro transcription system. The results indicate that PhoP approximately P is sufficient to repress the transcription of the tagA and tagD promoters and also to activate the transcription of the tuaA promoter.

Bacillus subtilis↗

PubMed1998

Mitochondrial gene defect in patients with chronic progressive external ophthalmoplegia.

OBJECTIVE: To detect the gene defect of mitochondrial DNA (mtDNA) from skeletal muscles in 2 patients with chronic progressive external ophthalmoplegia (CPEO). METHODS: After extraction of mtDNA, Southern hybridization was performed after restrictive digestion by Pvu II, EcoRI, Hind III, and Sacl. Then, we carried out polymerase chain reaction (PCR) and the enzyme digestion of the PCR products. Finally, mtDNA sequencing was done by automatic DNA sequence analyzer. RESULTS: In case 1, a 5 kb deletion was found by Southern blot analysis and PCR. And dosage analysis showed a heteroplasmic change with 44% mtDNAs deleted. In case 2, PCR plus restriction endonuclease Pvu II digestion demonstrated a mutation which was confirmed by DNA sequencing to be a single base substitution (T-->C) inducing a novel Pvu II site around 10,909 on mtDNA sequence. The laser image analyzer measurement revealed the mutation was almost homologous (99.4% mutant). CONCLUSIONS: In case 1, a 5 kb deletion found in mtDNA is called "common deletion" according to the literature. In case 2, a novel Pvu II site was found. It seems to be a de novo point mutation affecting ND4 in published CPEO research and is first reported in Chinese population. This point mutation does not induce an amino acid(Phe) change according to the published human mitochondrial genetic code as well as the mtDNA sequence. Whether it affects the translation efficiency or transportation of signals between mitochondrial and nuclear genome needs further studies.

Adult↗

PubMed1998

[The extended indications of near-total laryngectomy].

OBJECTIVE: To evaluate near-total laryngectomy in treatment of laryngeal cancers. METHODS: Fifty-seven near-total laryngectomies were reviewed, among them 40 were T3 or T4 laryngeal cancers due to tumor invasion to the base of tongue or subglottic region. RESULTS: In these patients, there were 11 cases of T3 pyriform sinus cancers, 5 cervical esophageal cancers, 1 case with adenoid cystic carcinoma involving the base of the tongue and oropharynx. Speech function had been preserved in 93% of cases with normal swallowing. Three year survival rates were 67.5% in laryngeal cancer and 50% in hypopharyngeal cancer. Local recurrence rate was only 3.5%. CONCLUSION: The authors believed that near-total laryngectomy is safe and beneficial to the patients with the above types of cancers. The quality of life may improve if speech function is preserved.

Aged↗

PubMed1998

[Corneal topography analysis after excimer laser photorefractive keratectomy].

OBJECTIVE: To study the pattern of ablation, evaluate centration and stability following excimer laser photorefractive keratectomy (PRK) for myopia. METHOD: Corneal topography of 312 patients (366 eyes) with a month, 3 months and 6 months of follow-up after PRK was examined. RESULTS: The mean decentration from the pupillary center to ablating center was 0.266 mm. In both eyes, the mean decentration was located supernasally. At one month postoperative examination, uniform ablation was 49.5%, semicircular, keyhole, kidney and dumbbell shaped ablations were 42.9% and central island one was 6.0%. Central island pattern affected the best corrected visual acuity greatly. High myopia began regression at 1-3 months after PRK. CONCLUSION: Corneal topography is essential for evaluating surface changes after PRK. Long-time stability issues are answered with continued topographic follow-up.

Corneal Topography↗

PubMed1998

Study on kinetics of ergosterol fermentation.

The kinetic relationships among the consumption of sucrose, production of ergosterol, formation of ethanol, and growth of yeast cells were studied. A two-stage kinetic model was established. The relative deviations between experimental data and simulated results were no more than 20%.

Ergosterol↗

PubMed1997

Genetic engineering of a recombinant fusion possessing anti-tumor F(ab')2 and tumor necrosis factor.

The construction, synthesis and expression of a genetically engineered bifunctional antibody/cytokine fusion protein is described. In order to target alpha-tumor necrosis factor (TNF) to tumor cells, recombinant antibody techniques were used to construct an RM4/TNF fusion protein containing the chimeric anti-tumor F(ab')2 (RM4) as well as the TNF moiety. The recombinant cDNA of human TNF was linked to the 3' end of the chimeric heavy-chain gene fragment (M4) containing the VH, the CH1 and the hinge region to form the fused heavy-chain gene fragment M4-TNF. Transfection of the M4-TNF gene fragment into a VKCK cell line producing the chimeric light-chain of the same antibody allowed the transfectant secreting the bifunctional fusion protein RM4/TNF. The RM4/TNF was purified by affinity chromatography. Our data showed that RM4/TNF retained the TAG72 antigen-binding reactivity as well as TNF activity as measured by ELISA, Western blotting, flow cytometry analysis, immunohistochemistry and cytotoxicity assays using the human colon cancer cell line LS174T. Therefore, the bifunctional fusion protein RM4/TNF may prove useful in targeting the biological effects of TNF to tumor cells, and in this way stimulate the immune destruction of tumor cells.

Adenocarcinoma↗

PubMed1997

Characterization of a CNS cell line, CAD, in which morphological differentiation is initiated by serum deprivation.

A CNS catecholaminergic cell line, Cath.a, was established by targeted oncogenesis in transgenic mice. Cath.a cells express neuronal properties but lack neuronal morphology. Here, we describe a variant of Cath.a, called CAD (Cath.a-differentiated), in which reversible morphological differentiation can be initiated by removal of serum or exogenously added protein from the medium. In serum- or protein-free media, CAD cells stop proliferating and extend long processes. Differentiated CAD cells can be maintained without serum or protein for at least 6 weeks. CAD cells are distinct from Cath.a cells; most significant, the original immortalizing oncogene, SV40 T antigen, was spontaneously lost. By immunostaining or immunoblotting, we show that CAD cells express neuron-specific proteins, such as class III beta-tubulin, GAP-43, SNAP-25, and synaptotagmin, but not GFAP. Ultrastructurally, processes from differentiated CAD cells have abundant parallel microtubules and intermediate filaments, and bear varicosities that contain both large dense-core vesicles/granules (120-160 nm) and smaller clear vesicles (60-80 nm). Additionally, CAD cells express enzymatically active tyrosine hydroxylase and accumulate L-DOPA. CAD cells exhibit biochemical and morphological characteristics of primary neurons and provide an unique tool for studying neuronal differentiation.

Animals↗

PubMed1997

HNK-1 epitope in the lens-ciliary zonular region in normal and pseudoexfoliative eyes. Immunohistochemistry and ultrastructure.

OBJECTIVE: To determine the specific binding sites for the HNK-1 adhesion molecule epitope in the lens-ciliary zonular region in normal and pseudoexfoliative (PSX) eyes. METHODS: Normal and PSX eyes and adjacent tissues from individuals aged 10 months to 89 years were investigated for the HNK-1 epitope by immunohistochemistry and immunogold electron microscopy. RESULTS: Concentration of HNK-1 epitope was high in the anterior central lens capsule into old age, but it tapered earlier and progressively in the inner capsule and elsewhere. On zonular fibers, label was strongest at their lens and ciliary attachments and intense on related elastic microfibrils in adjacent ciliary stroma. Label was also strong on PSX fibers and above normal on PSX central capsule. In contrast, HNK-1 was absent on PSX aggregates in conjunctiva and skin and on normal elastic microfibrils in these tissues. CONCLUSIONS: The prominent HNK-1 epitope in lens capsule and zonule has age- and site-specific variations that favor adhesive roles in each. The high density of epitope on ocular PSX material suggests an aberrant increase in expression that may contribute to adhesiveness of these aggregates, HNK-1 negativity on extraocular elastic microfibrils and PSX aggregates indicates a unique difference in composition of intraocular and extraocular elastic tissue, of potential significance for ocular function in aging and lens-dislocating diseases.

Adolescent↗

PubMed1997

Exfoliation syndrome in a 17-year-old girl.

A 17-year-old girl with unilateral congenital glaucoma who had undergone trabeculectomy and peripheral iridectomy in infancy developed apparent exfoliation syndrome (XFS) in the eye that underwent the surgical procedures. A conjunctival biopsy was performed and the specimen was fixed in 2.5% glutaraldehyde, embedded in epoxy resin (Epon-Araldite, Electron Microscopy Sciences, Fort Washington, Pa), and processed for routine electron microscopy and immunostaining for elastin. Results of ultrastructural study showed scattered fibrillar aggregates compatible with those of XFS in an older adult, differing chiefly in sparsity of granular interfibrillar matrix. The XFS fibers were closely associated with elastic fibers and microfibrils. Elastosis of the actinic-aging type was somewhat greater than expected for age. To our knowledge, this is the youngest patient described with characteristic ocular findings of XFS to date, supporting others who have suggested an association between iris surgery in youth and early onset XFS. Electron microscopy was essential in ruling out the possibility of a clinically similar entity caused by ultrastructurally different material.

Adolescent↗

PubMed1997

Mutational analysis of mitochondrial DNA of children with Rett syndrome.

The present study was undertaken to identify whether mitochondrial DNA (mtDNA) mutations were involved in the pathogenesis of Rett syndrome (RS). Mitochondrial DNA from 15 children with RS and 14 of their mothers was analyzed. No large deletions in mtDNA were found using Southern blot with a full-length mtDNA as a probe. Polymerase chain reaction amplification and single strand conformation polymorphism analysis showed mutations in region 2650-3000 encoding 16S rRNA of mtDNA in 13 cases of RS and 11 of their mothers. DNA sequence analysis and mismatch polymerase chain reaction results revealed a point mutation (C --> T) at position 2835 in 7 cases of RS and 6 of their mothers. The same mutation was not found in a total of 30 normal controls. These data indicate that mtDNA may play an important role in the pathogenesis of RS.

Case-Control Studies↗

PubMed1997

Nucleotide sequence of a 5423 base pairs fragment of the LsNPV genome and comparison with the AcNPV genome.

A 5423 bp fragment of LsNPV genome was sequenced, in which PDV-E66 gene and another four ORFs were found. The PDV-E66 gene of LsNPV was compared with the PDV-E66 gene of AcNPV, and a 51.9% nucleotide sequence homology and 38.8% amino acid sequence homology were found between the two genes. Two conserved late transcriptional motifs TAAG were found in LsNPV PDV-E66 gene, similar to those in AcNPV PDV-E66. The LsNPV PDV-E66 ORF is 204 base pairs shorter than the AcNPV PDV-E66 ORF at the 5' end. This is agreement with the fact that the N-terminus of the AcNPV PDV-E66 mature protein is 69 amino acids interior to the N-terminus predicted by the AcNPV PDV-E66 ORF. The 5' regulatory region of ORF1 contains early (CGTGC) and late (TAAG) transcriptional initiation motifs and ORF1 is predicted to encode a protein with 114 amino acid residues. The 5' regulatory region of ORF2 which can encode a protein with 115 amino acid residues contains only an early transcriptional initiation motif. Compared with all the genes from AcNPV and other baculoviruses, ORF1 and ORF2 have no homologous genes. It is suggested that ORF1 and ORF2 may be two novel baculovirus genes. ORF3 (PDV-E66 gene), ORF5 and an incomplete ORF, ORF6-part, have homologous regions in the AcNPV genome. ORF3, ORF5, ORF6-part are linked together in LsNPV genome, but their homologous regions are separated by about 58 kb fragment in the AcNPV genome. This fact indicates that the organization of the above genes in LsNPV is different from that of AcNPV. ORF4 is included in ORF6-part and can encode a 48 amino acid residues polypeptide, but ORF4 and ORF6-part are located on different DNA strands.

Amino Acid Sequence↗

PubMed1997

Risk factors for bladder cancer: a case-control study in northeast China.

A case-control study of risk factors for bladder cancer was carried out in Heilongjing Province, China. Between May 1989 and May 1990, 217 histologically confirmed cases of bladder cancer and 254 controls with non-neoplastic and non-urine system disease were recruited. Individuals were interviewed in the wards of six major hospitals. Controls were matched by sex, age and area of residence. Information was collected concerning economic status, occupation, histories of smoking and consumption of alcohol, use of tea, the taking of analgesics, dietary histories and previous diseases. Odds ratios (ORs) were calculated from stratified analysis and conditional logistic regression models. Increased risk was observed with increasing times per year and number of years of saccharine use. Compared with non-users, the use of saccharine for more than 19 times per year, and for more than 15 years, the adjusted ORs were 3.9 (95% CI = 1.8-8.67) and 5.1 (95% CI = 2.3-11.6), respectively. Statistically significant associations were also found for diseases related to the urinary system (OR = 2.8; 95% CI = 1.1-7.6). Increased consumption of fruit and vegetable may reduce the risk of bladder cancer. Cigarette smoking had no effect on the risk of bladder cancer in both genders. There was no association between the consumption of alcohol or tea, or types of water supply, with bladder cancer risk.

Adult↗

PubMed1997

Temporal and spectral estimations of harmonics-to-noise ratio in human voice signals.

The quantity, harmonic-to-noise ratio (HNR), has been used to estimate the level of noise in human voice signals. HNR estimation can be accomplished in two ways: (1) on a time-domain basis, in which HNR is computed directly from the acoustic waveform; and (2) on a frequency-domain basis, in which HNR is computed from a transformed representation of the waveform. An algorithm for computing HNR in the frequency domain was modified and tested in the work described here. The modifications were designed to reduce the influence of spectral leakage in the computation of harmonic energy, and to remove the necessity of spectral baseline shifting prescribed in one existing algorithm [G. de Krom, J. Speech Hear. Res. 36, 254-266 (1993)]. Frequency-domain estimations of HNR based on this existing algorithm and our modified algorithm were compared to time-domain estimations on synthetic signals and human pathological voice samples. Results indicated a highly significant, linear correlation between frequency- and time-domain estimations of HNR for our modified approach.

Female↗

PubMed1997

The pst operon of Bacillus subtilis has a phosphate-regulated promoter and is involved in phosphate transport but not in regulation of the pho regulon.

Genes from Bacillus subtilis predicted to encode a phosphate-specific transport (Pst) system were shown by mutation to affect high-affinity Pi uptake but not arsenate resistance or phosphate (Pho) regulation. The transcription start of the promoter upstream of the pstS gene was defined by primer extension. The promoter contains structural features analogous to the Escherichia coli pst promoter but not sequence similarity. Expression from this promoter was induced >5,000-fold upon phosphate starvation and regulated by the PhoP-PhoR two-component regulatory system. These data indicate that the pst operon is involved in phosphate transport and is a member of the Pho regulon but is not involved in Pi regulation.

ATP-Binding Cassette Transporters↗

PubMed1997

No evidence for uniparental disomy as a common cause of Sotos syndrome.

A number of rare diseases (including Sotos syndrome) of unknown aetiology, which occur mainly sporadically and with features of growth disorder and developmental delay, may be caused by imprinted genes and therefore be associated with UPD. Using 112 dinucleotide repeat DNA polymorphisms, we have examined parental inheritance of all autosome pairs, except chromosome 15, in 29 patients with Sotos syndrome. All informative cases showed biparental inheritance and no cases of UPD were found. We conclude that Sotos syndrome is either not caused by an imprinted gene or that UPD is rare or of a segmental form in its aetiology.

Chromosome Aberrations↗

PubMed1997

Cardiovascular response to stress: baroreflex resetting and hemodynamics.

Borderline hypertensive rats (BHR) were used to test the hypothesis that baroreflex resetting prevents a fall in blood pressure (BP) when cardiac output (CO) is reduced during air-jet stress. Eight-week-old BHR were instrumented with flow probes around the ascending aorta for measuring CO, femoral and jugular catheters were inserted for measurement of arterial pressure and infusion of drugs, and sinoaortic baroreceptors were either denervated (SAD) or left intact. Alternating bolus injections of phenylephrine and sodium nitroprusside were given at baseline and during air-jet stress to assess the baroreflex. Air-jet stress immediately shifted the midpoint of the baroreflex curve for heart rate (HR) to a higher BP levels. When metoprolol was administered during air-jet stress, HR was reduced and CO reverted to prestress levels, but the stress-induced pressor response was not changed. In SAD BHR, air-jet stress caused an elevation of BP that was not different from intact rats. Administration of metoprolol to SAD rats during air-jet stress resulted in a further elevation rather than a reduction in BP. We conclude that the sinoaortic cardiac baroreflex is reset during air-jet stress and that it integrates reflex changes in BP during stress. The arterial baroreflex is not, however, necessary for the initiation or maintenance of the pressor response during stress, nor does it prevent a fall in BP when CO is compromised during stress.

Animals↗

PubMed1997

[Effects of cytokines on multidrug-resistance in K562/A02 cells].

OBJECTIVE: To explore the effects of cytokines on human leukemic cell line K562/S and its multidrug-resistant counterpart K562/A02. METHODS: The toxicities of cytokines and the IC50 (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method; intracellular drug concentration was measured by fluorometry; p-glycoprotein (p-gp) expression was detected by APAAP and mdr-1 mRNA was assayed by RT-PCR. RESULTS: The IC50 of DNR for K562/A02 and K562/S cells were 45.08 microg/ml and 0.607 microg/ml, respectively. Pretreating K562/A02 cells with rhu IFN (500 U/ml) or rhu IL-2 (250 U/ml) for 24 hours partially restored the sensitivity of K562/A02 cells to DNR (IC50 were 16.39 and 11.96 microg/ml, respectively) but had not effect on K562/S cells, and it elevated the intracellular DNR accumulation in K562/A02 from 2151 ng/mg x protein to 2570 and 2503ng/mg x protein, respectively. p-gp and mdr-1 mRNA were not down regulated. By contrast, rhu G-CSF and rhu GM-CSF had no effect on either K562/A02 or K562/S. CONCLUSION: rhu IFN or rhu IL-2 could partially restore the sensitivity of K562/A02 to DNR and elevate the intracellular DNR accumulation via a mechanism independent of p-gp or mdr-1 mRNA down-regulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗