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Biomedical subjects

Q Yu

Publications and source records attributed to Q Yu.

At least 271 records · Page 15Linked to original sources
PubMed1992

Molecular analysis of neurofibromatosis type 1 mutations.

We have examined a panel of 115 unrelated NF1 individuals for mutation in the 3' region of the NF1 gene, using Southern blotting and polymerase chain reaction amplification of exons followed by single-strand conformation polymorphism (SSCP) analysis. We found only 2 unequivocal mutations: a 571 bp deletion which removed exon 6 and resulted in a frameshift in exon 7, and a 2 bp deletion in exon 1. A third sequence variation detected by SSCP was predicted to cause a lysine-arginine substitution in exon 6. This is a conservative change, and since the affected individual is a new mutation whose parents are not available, we cannot be sure of its biological significance. We detected mutations in at most 3% of individuals, from an analysis which covered 17% of the coding sequence by SSCP and a larger region by Southern blotting. This relative failure to detect mutations accords with the experience of others. Even allowing for the incomplete sensitivity of the methods used, the results suggest that the majority of NF1 mutations lie elsewhere in the coding sequence or outside it.

Base Sequence↗
PubMed1992

Genomic mapping by single copy landmark detection: a predictive model with a discrete mathematical approach.

One of the goals of the Human Genome Project is to produce libraries of largely contiguous, ordered sets of molecular clones for use in sequencing and gene mapping projects. This is planned to be done for human and many model organisms. Theory and practice have shown that long-range contiguity and the degree to which the entire genome is covered by ordered clones can be affected by many biological variables. Many laboratories are currently experimenting with different experimental strategies and theoretical models to help plan strategies for accomplishing long-range molecular mapping of genomes. Here we describe a new mathematical model and formulas for helping to plan genome mapping projects, using various single-copy landmark (SCL) detection, or "anchoring", strategies. We derive formulas that allow us to examine the effects of interactions among the following variables: average insert size of the cloning vector, average size of SCL, the number of SCL, and the redundancy in coverage of the clone library. We also examine and compare three different ways in which anchoring can be implemented: (1) anchors are selected independently of the library to be ordered (random anchoring); (2) anchors are made from end probes from both ends of clones in the library to be ordered (nonrandom anchoring); and (3) anchors are made from one end or the other, randomly, from clones in the library to be ordered (nonrandom anchoring). Our results show that, for biologically realistic conditions, nonrandom anchoring is always more effective than random anchoring for contig building, and there is little to be gained from making SCL from both ends of clones vs. only one end of clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosome Mapping↗
PubMed1992

Effect of dietary fluoride on selenite toxicity in the rat.

Three factorial experiments were conducted to determine if high dietary fluoride (F) would inhibit selenite toxicity in rats. Initially, three levels of selenite (0.05, 3, and 5 mg/kg diet) were matched against three levels of F (2, 75, and 150 mg/kg diet). Fluoride failed to prevent the depressive effect of selenite on 8-wk food intake and body wt gain. Selenium (Se) concentration of plasma and kidney and enzymatic activity of whole blood glutathione peroxidase (GSH-Px) were also unaffected by F. Liver Se concentration, however, was slightly (12%) but significantly (p < 0.025) reduced when the highest F and Se levels were combined. Fluoride (150 mg/kg) appeared to reduce liver selenite toxicity (5 mg/kg). Therefore, further study focused on liver histology with treatments that eliminated the middle levels of selenite and F. Fluoride prevented the hepatic necrosis seen in selenite-toxic rats. Similar histological lesions were not observed for kidney or heart. Fluoride partially (26%) but significantly (p < 0.025) reduced thiobarbituric-reactive substances in selenite-toxic rats, but there was no F effect on intracellular distribution of liver Se, glutathione levels in liver and kidney, or on liver xanthine oxidase activity. Overall, the protective effect of F on selenite toxicity appears to be confined to liver pathology. The exact mechanism for this effect, however, remains unclear.

Animals↗
PubMed1992

A radiologic study of pulmonary metastases originating from oral and maxillofacial tumors.

A retrospective clinical and radiologic study was carried out on 103 consecutive cases of oral and maxillofacial malignant conditions in which pulmonary metastasis occurred. The most frequent primary site was the palate. The neoplasm most commonly involved was the adenoid cystic carcinoma. Pulmonary metastases were classified into five types: solitary, multiple nodular, multiple "massy," diffuse, and miliary.

Adolescent↗
PubMed1992

Cloning and sequencing of the matrix protein (M) gene of turkey rhinotracheitis virus reveal a gene order different from that of respiratory syncytial virus.

Several biochemical properties and the sequence of the fusion glycoprotein (F) have indicated that turkey rhinotracheitis virus (TRTV) is a pneumovirus, subfamily Pneumovirinae of the Paramyxoviridae family. As TRTV was known to generate polycistronic mRNAs, cDNA was generated from TRTV strain UK/3BV/85-infected Vero cell mRNAs using an oligonucleotide primer corresponding to a region of the F gene. Sequencing of four cDNAs revealed that the gene adjacent to the beginning (3' end) of the F gene was that for the matrix (M) protein, i.e., that TRTV had the partial gene order 3'-M-F-5'. This was unexpected as human respiratory syncytial (RS) virus, the type species of the genus Pneumovirus, has the partial gene order 3'-M-SH-G-F-5', where SH and G are the small hydrophobic protein and attachment glycoprotein, respectively. Instead TRTV resembled the Morbillivirus and Paramyxovirus genera of the Paramyxoviridae (subfamily Paramyxovirinae) which have the partial gene order 3'-M-F-5'. Two further oligonucleotides, one corresponding to a sequence near the end of the M gene and the other (oligo B) to a sequence near the beginning of the F gene, with their 5' ends spaced 300 nucleotides apart on the basis of the cDNA sequence, were used in a polymerase chain reaction (PCR) using genomic RNA as template. Only a PCR product of 0.3 kb was obtained. The same sized product was also obtained using these oligonucleotides and genomic RNA from three other TRTV strains (SA/91/78, UK/8544/85, and SA/2381/88) which had been grown in chicken tracheal organ cultures. In addition PCR was performed using genomic RNA from TRTV-3BV and SA/2381/88 with oligo B and another oligonucleotide near the 5' end of the gene upstream from M, spaced 1141 nucleotides apart on the basis of the sequence data. Only a 1.14-kb PCR product was obtained. Larger products would have been expected if another gene had been situated between M and F. The absence of such larger products, plus the demonstration that infected cells contained M-F dicistronic mRNAs, supported the conclusion that in the TRTV genome the M gene is adjacent to the F gene in the order 3'-M-F-5'. The 5' termini of the M and F mRNAs were confirmed by mRNA mapping. The TRTV M gene encoded a protein of 254 amino acids, very similar to that of RS virus (256 residues; 37% amino acid identity) but very different from that of the morbilliviruses and paramyxoviruses (approximately 350 residues).(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Sequence and in vitro expression of the M2 gene of turkey rhinotracheitis pneumovirus.

Negative-stranded virion RNA and oligonucleotide primers complementary to fusion (F) protein gene sequences were used to generate cDNA clones, revealing that the gene 5'-proximal to the F protein corresponded to the M2 (22K) gene, as in respiratory syncytial (RS) virus. The transcription start signal, GGGACAAGU, was identical to that of the F and matrix (M) proteins of turkey rhinotracheitis virus (TRTV). There were two sequences with the potential to function as transcription termination/poly(A) signals, located at nucleotides 751 to 762 and 777 to 787; 15 clones derived from mRNA indicated that the first of these sequences formed the major signal. Part of the next downstream (5') gene was sequenced; unlike mammalian pneumoviruses the TRTV M2 gene did not overlap the beginning of the 5'-proximal gene. Northern blotting indicated that infected Vero cells contained less M2 mRNA than F mRNA and that about half of the M2 mRNA was present as a F-M2 dicistronic mRNA. The M2 gene contained two overlapping open reading frames (ORFs 1 and 2), as with RS virus. ORF 1 comprised 558 nucleotides with the coding potential for a 186 amino acid polypeptide, M(r) 20959, eight or nine residues shorter than for human RS virus strains. The overall amino acid identity was 40%, the N-terminal one-third of the proteins sharing 62% of residues, the remainder 29%. A hydropathy plot of the TRTV M2 protein had close similarity to that of the M2 or RS virus. The protein was predicted to have a basic character with no N-terminal signal sequence or other major highly hydrophobic sequences. In vitro translation of a transcript comprising both ORFs 1 and 2 produced a single product of apparent M(r) 23000, corresponding to the M2 product of ORF 1. Site-directed mutagenesis confirmed that this product was derived from ORF 1 and that frameshifting was not involved. The second ORF was expressed only from a transcript which lacked the AUG codons of ORF 1 and, although occupying a similar position to that in the RS virus M2 gene, had virtually no amino acid identity in its 73 residue length and was approximately 25% shorter than the corresponding RS virus ORF 2. The hydropathy plot of the potential products of the second ORFs of TRTV and RS virus showed little resemblance. Taken together these results suggest that ORF 2 is unlikely to be expressed in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

[An epidemiological survey and treatment of blindness in Kaipin County of Guangdong Province].

An epidemiological survey of blindness was carried out in Kaipin County of Guangdong Province during October 1989 to May 1990, by stratified random cluster sampling. The sample population was 11,588, and the rate of blindness was 0.216%. The prevalence of blindness in persons aged 60 years and over was 48 times those of all other age groups combined. Since cataract accounted for 64% of the total blind cases, hence it was the key objective for surgical restoration of vision. Among 109 patients who were operated on for cataract, 83 cases were re-examined a half year later, and 78 cases (94%) had vision over 0.05.

Adolescent↗
PubMed1992

The N-terminal and C-terminal domains of a receptor tyrosine phosphatase are associated by non-covalent linkage.

We have cloned the rat homolog of the human leukocyte common antigen-related gene (LAR), which encodes a transmembrane receptor phosphotyrosine phosphatase, and raised antibodies against its protein product. We present evidence here for a processing event resulting in a two-chain structure of the mature receptor on the cell surface. The LAR protein is synthesized as a 190-kDa precursor which is subsequently cleaved into 145-kDa and 85-kDa fragments. The 145-kDa fragment, representing the amino terminus of the protein, is exclusively extracellular and is modified by N-linked glycosylation. The 85-kDa component, derived from the C-terminus of the protein, contains the transmembrane region and intracellular phosphotyrosine phosphatase domains. The two products, associated in a non-covalent manner, comprise the functional LAR cell-surface receptor.

Amino Acid Sequence↗
PubMed1992

[The role of peripheral C afferent fiber in electroacupuncture analgesia].

Experiments were carried out in rats anaesthetized with urethane (1 g/kg). Late discharges of spinal dorsal horn neurons were recorded as noxious responses to strong stimulation of right tibial nerve (a train of 3 pulses, 25V, 1ms). Left St.36 and Sp.6 were stimulated electrically (100Hz, 3V or 6V, 1ms). Left sciatic nerve was exposed and soaked for 15 min in 1.5% capsaicin or vehicle 24 hours before experiment. Left femoral nerve was sectioned. Spinal cord was transected at T4 level in spinal rat. Intact rats: 1) EA group (N = 12). Sciatic nerve was not treated. Late discharges of neuron were reduced to 44.6 +/- 18.3% of control (P less than 0.02) by EA(3v). 2) Capsaicin group (N = 15). Late discharges were reduced to 89.8 +/- 6.0% of control (P greater than 0.05) by EA(3V). 3) Vehicle group (N = 10). Late discharges were reduced to 51.2 +/- 15.6% of control (P less than 0.05) by EA(3V). 4) There was a statistical difference (P less than 0.05) between capsaicin and vehicle group. Spinal rats: 1) EA group. Late discharges of neuron were reduced to 67.6 +/- 10.3% of control (P less than 0.02) in 11 neurons by EA(3V), 72.7 +/- 8.8% (P less than 0.01) in 9 neurons by EA(6V). 2) Capsaicin group. Late discharges were 110 +/- 21.0% of control (P greater than 0.05) in 13 neurons after termination of EA (3V), 90.7 +/- 12.9% (P greater than 0.05) in 10 neurons after EA (6V). 3) Vehicle group. Late discharges were reduced to 67.7 +/- 8.1% of control (P less than 0.02) in 12 neurons by EA (3V), 68.1 +/- 5.0% (P less than 0.01) in 10 neurons by EA (6V). 4) There was a statistical difference (P less than 0.05) between capsaicin and vehicle group for 3V, no statistical difference (P greater than 0.05) for 6V. C fiber of peripheral nerve is main component involved in effect of EA analgesia in intact rats. Both A and C fiber of peripheral nerve involved in effect of EA analgesia in spinal rats.

Acupuncture Analgesia↗
PubMed1991

Molecular transfer of a species-specific behavior from Drosophila simulans to Drosophila melanogaster.

Drosophila males modulate the interpulse intervals produced during their courtship songs. These song cycles, which are altered by mutations in the clock gene period, exhibit a species-specific variation that facilitates mating. We have used chimeric period gene constructs from Drosophila melanogaster and Drosophila simulans in germline transformation experiments to map the genetic control of their song rhythm difference to a small segment of the amino acid encoding information within this gene.

Amino Acid Sequence↗
PubMed1991

Deduced amino acid sequence of the fusion glycoprotein of turkey rhinotracheitis virus has greater identity with that of human respiratory syncytial virus, a pneumovirus, than that of paramyxoviruses and morbilliviruses.

The sequence of the fusion (F) glycoprotein of turkey rhinotracheitis virus (TRTV) has been deduced from cDNA clones derived from oligo(dT)-selected infected cell RNA. The protein consists of 538 amino acids, the F2 and F1 subunits containing 102 (including the F2-F1 connecting peptide RRRR) and 436 residues, respectively. Each subunit has one potential N-linked glycosylation site. The protein has 38 to 39% amino acid identity with the F protein of respiratory syncytial virus (Pneumovirus genus) but only about half that with members of the other two genera (Paramyxovirus and Morbillivirus) in the Paramyxoviridae family. This is the first sequence evidence to support the view that TRTV is a pneumovirus, the first avian member of the genus to be described.

Amino Acid Sequence↗
PubMed1991

Titrating luteinizing hormone surge requirements for ovulatory changes in primate follicles. II. Progesterone receptor expression in luteinizing granulosa cells.

The events in granulosa cells that are initiated by the midcycle LH surge during luteinization of the primate follicle are poorly defined. This study was designed 1) to determine whether an ovulatory dose of hCG can induce progesterone receptors (PR) in macaque granulosa cells, and if so, 2) to begin titrating gonadotropin requirements for PR expression and progesterone production by luteinizing granulosa cells. Rhesus monkeys were treated with human FSH and LH for up to 9 days to stimulate the growth of multiple follicles. The next day, animals (n = 4-5/group) received: 1) no ovulatory stimulus; 2) 1000 IU hCG, im; 3) one injection of 100 micrograms GnRH, sc (GnRH-1); 4) three injections of GnRH (GnRH-3) at 3-h intervals (0800, 1100, and 1400 h); or 5) two injections of 50 micrograms GnRH agonist (GnRHa), sc, 8 h apart (0800 and 1700 h). Granulosa cells obtained by follicle aspiration 27 h after the hCG or initial GnRH/GnRHa injection or on days 8 or 10 from animals receiving no ovulatory stimulus were processed for indirect immunocytochemistry using a monoclonal antibody to human PR (JZB39). Specific staining for PR, determined by comparing cells incubated with PR antibody vs. a nonspecific antibody, was undetectable in granulosa cells from monkeys without an ovulatory stimulus. In contrast, the majority (64 +/- 5%) of cells from hCG-treated animals stained intensely for PR. In the GnRH/GnRHa groups, granulosa cells from only one animal (i.e. one GnRH-3 monkey) showed positive staining for PR. During 24-h culture in Ham's F-10 medium containing 10% monkey serum, basal progesterone production by cells from the hCG-treated group (2163 nmol/L.8 x 10(4) cells) was higher than that by cells from the no ovulatory stimulus/GnRH-1/GnRH-3/GnRHa groups (60, 111, 194, and 332 nmol/L, respectively). However, granulosa cells from the hCG-treated group were less responsive to hCG in vitro in terms of enhanced progesterone production (2 times control levels) than cells from the other four groups (up to 30 times control levels). This study provides direct evidence that an ovulatory dose of hCG induces PR expression in granulosa cells of luteinizing follicles during stimulated cycles in rhesus monkeys. However, repeated injections of GnRH/GnRHa that produced surge levels (greater than 100 ng/mL) of endogenous LH for up to 14 h failed to induce PR expression or progesterone production by granulosa cells. Thus, an extended LH surge more typical of that in the normal menstrual cycle (48-50 h) may be necessary for PR expression and luteinization of granulosa cells in primate follicles.

Animals↗
PubMed1991

HLA antigens and Vogt-Koyanagi-Harada's disease.

Thirty patients with Vogt-Koyanagi-Harada's disease were typed for HLA-A and HLA-B antigenic determinants by a microlymphocytotoxicity technique. HLA-B22 antigen showed an increased frequency of 43.3% in the patient group (relative risk = 8.69; exact P < 0.0001; corrected P < 0.0025) compared with normal control group (frequency = 7.69%). This association suggests that immunogenetic factor may play an important role in the pathogenesis of Vogt-Koyanagi-Harada's disease.

China↗
PubMed1991

Intravenous recombinant tissue-type plasminogen activator in acute myocardial infarction.

The efficacy and safety of intravenously administered recombinant tissue-type plasminogen activator (rt-PA, Boehringer Ingelheim Corp.) was investigated in 10 patients with acute myocardial infarction (AMI). rt-PA was given as a 10 mg bolus dose followed by infusions of 50 mg, 20 mg and 20 mg in three successive hours. All patients underwent baseline coronary angiography before thrombolytic therapy. Ninety minutes after the initiation of rt-PA infusion, recanalization of infarct-related coronary arteries as confirmed by angiography was achieved in 7 patients. The largest reduction in circulating fibrinogen was observed 4 to 6 h after the start of rt-PA infusion--14.3%. Moderate hemorrhage at the sites of arterial puncture occurred in 2 cases, probably as a result of heparin anticoagulation. No other side effects occurred. So rt-PA is an effective and safe thrombolytic agent.

Aged↗
PubMed1991

Secondary prevention of myocardial reinfarction with low dose aspirin.

A clinical trial of secondary prevention of reinfarction with low dose aspirin is reported. 50 mg aspirin per day was administered in 216 case. 211 cases did not take aspirin or any other antiplatelet agents as a control group. The follow-up periods in the two groups were 19.4 +/- 12.6 mon and 20.7 +/- 13.0 mon, respectively. There were 175 males in the aspirin group and 137 males in the control group. The incidence of reinfarction was reduced by 65% and platelet aggregation was inhibited obviously in the aspirin group as compared to the control group in men, whereas no significant trends were observed in women.

Aged↗
PubMed1991

Evaluation of a lens opacities classification system II (LOCS II) in the survey population-based sample.

In the field work of population-based research, 3 groups of eyes were graded by 2 observers in LOCS II. The reproducibility of LOCS II was evaluated by agreements (85%-100%) and k values (0.661-1) obtained in our study. The satisfying results show that LOCS II is not only easy to be learned and to be applied consistently by different observers, but also good reproducibility in the field work. The longitudinal cataract study is going to be performed in our plan.

Cataract↗
PubMed1991

[CA125 and radioimmunoimaging in monitoring of epithelial ovarian carcinoma].

Serum CA125 was measured by monoclonal antibody-OC125 in 50 primary and 29 suspected recurrent ovarian cancer patients. Among the later, RII examination by using 131I labelled polyclonal antibody-OCOV3 was carried out in 16 cases at the same time. For the suspected recurrent cases, the results, as checked by surgico-pathological findings, revealed a corroborative rate of 79.3% for CA125 assay and 87.5% for RII technique. The positive predictive value of both CA125 assay and RII were 100%, while the negative predictive value was only 25% for CA125 assay and 50% for RII technique. However, for each individual case if the results of the two tests were combined, the negative predictive value was also 100%. Preoperative CA125 level had no significant relationship with the prognosis in primary cases. But the two year survival rate for recurrent cases with a preoperative CA125 less than or equal to 35,000 U/L was much higher than those with CA125 greater than 35,000 U/L.

Antibodies, Monoclonal↗