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Biomedical subjects

Y Qi

Publications and source records attributed to Y Qi.

At least 163 records · Page 9Linked to original sources
PubMed1994

Single-chain antibody variable region-targeted interleukin-2 stimulates T cell killing of human colorectal carcinoma cells.

Recombinant DNA techniques were used to clone, construct and express the bifunctional molecule FV/IL-2. The FV/IL-2 is a single-chain 37 kDa fusion protein expressed in Escherichia coli under control of the strong T7 bacteriophage promoter in the expression vector pT7-7-FV-IL-2. The fused gene fragment FV-IL-2 contains a single-chain anti-TAG72 FV gene fragment and the human recombinant cDNA fragment of the IL-2 molecule. The renatured soluble form of FV/IL-2 was purified from E. coli inclusion bodies using hydroxylapatite chromatography. The yield of this fusion protein was estimated at 2.0 mg/L. Our data showed that the FV/IL-2 molecule retained the TAG72 antigen-binding specificity and the IL-2 activity as measured in the standard T cell proliferation as well as cytotoxicity assays. Therefore, it may prove to be useful in targeting the biological effect of IL-2 to tumour cells and stimulating its immune destruction.

Amino Acid Sequence↗
PubMed1994

A homomorphic method for measuring secondary amplitude modulation.

A homomorphic processing, software implemented method for measuring secondary amplitude modulation (AM) is described. The accuracy of measurement of this method was tested on a series of synthetically produced AM and vowel signals. The homomorphic method provided highly accurate measurement of modulation frequency and modulation index.

Humans↗
PubMed1994

Hypoxia specifically and reversibly induces the synthesis of ferritin in oligodendrocytes and human oligodendrogliomas.

Neonatal (3 day old) rat oligodendrocytes grown in monolayer culture and exposed to increasingly hypoxic culture conditions showed increased Tran35S-label incorporation into a 22-kDa protein. Reoxygenation of cultures reversed the synthesis of the protein. Amino acid sequencing of a peptide derived from the purified protein revealed a 13 amino acid sequence with complete identity to a human heavy chain subunit of ferritin. This was confirmed by two-dimensional gel electrophoresis, immunoprecipitation, and western blot analysis with antiferritin antibody. In addition, hypoxia was able to induce the synthesis of ferritin in a cell line derived from human oligodendroglioma cells but not in astrocytes or neurons. Actinomycin D (1-15 micrograms/ml) treatment did not block the hypoxic induction of ferritin synthesis, whereas cycloheximide (1 microM) gave complete inhibition. Northern blot analysis showed that ferritin mRNA levels remained unchanged in both control and hypoxic oligodendrocytes and human oligodendroglioma cells, suggesting that the synthesis of ferritin was translationally rather than transcriptionally regulated by hypoxia. In neither oligodendrocytes nor the oligodendroglioma was there any cross-reaction with an antibody to alpha B-crystallin, the 22-kDa protein induced in astrocytes by various types of stress, further suggesting the specificity of hypoxic induction of ferritin in oligodendrocytes.

Amino Acid Sequence↗
PubMed1994

Suppression of thyrotropin-releasing hormone gene expression by interleukin-1-beta in the rat: implications for nonthyroidal illness.

Nonthyroidal illness is characterized by low thyroid hormone levels and inappropriately normal or decreased TSH levels. To determine whether the hypothalamus contributes to these responses, TRH gene expression in hypophysiotropic neurons of the paraventricular nucleus (PVN) was investigated using semiquantitative in situ hybridization histochemistry in an animal model of nonthyroidal illness. Following the systemic administration of bacterial lipopolysaccharide (LPS; 250 micrograms/100 g BW), plasma T4, T3 and TSH were reduced but this was not associated with an increase in the content of proTRH mRNA in the PVN as occurs when plasma T4 and T3 concentrations fall during primary hypothyroidism. Constant infusion of human interleukin-1 beta (IL-1 beta) into the cerebrospinal fluid also reduced plasma T4 concentration. This persisted for the duration of the infusion but TSH was only suppressed after 7 days of infusion when body weight had declined. By 24 h, the content of proTRH mRNA in the PVN in IL-1 beta infused animals was significantly reduced from control values. These studies indicate that the peripheral administration of endotoxin or central administration of IL-1 beta in the rat is associated with a proTRH mRNA content in the PVN that may be inappropriately normal or reduced for the level of circulating thyroid hormone. We propose that the inability of hypophysiotropic neurons to induce TRH gene expression in nonthyroidal illness, when circulating thyroid hormone levels are low, is one of several factors that contributes to the inability of the anterior pituitary to increase its secretion of TSH.

Animals↗
PubMed1994

Identification of thyroid hormone receptor isoforms in thyrotropin-releasing hormone neurons of the hypothalamic paraventricular nucleus.

TRH gene expression in hypophysiotropic neurons of the hypothalamic paraventricular nucleus (PVN) is under regulation by thyroid hormone circulating in the bloodstream. To determine whether thyroid hormone could exert effects directly on TRH-producing neurons in the PVN, the presence of thyroid hormone receptors (TR) in these neurons was determined by double labeling immunocytochemical techniques, using specific antiserum to each of the functional TRs, TR alpha 1, TR beta 1, and TR beta 2, followed by antiserum to prepro-TRH-(25-50) as a marker for TRH neurons. In addition, the presence of the TR variant, TR alpha 2, was sought in these cells. Immunoreactive TR alpha 1 and TR beta 2 were found in the greatest percentage of TRH neurons in the PVN (91.1 +/- 2.5% and 83.8 +/- 2.1%) and intensely stained the nucleus. Immunoreactive TR beta 1 was also found in the majority of TRH neurons, but stained PVN cells only lightly compared to the other TRs. TR alpha 2 was found to coexist in only a minority of TRH neurons in the PVN and also lightly immunostained the nucleus compared to its more intense labeling in other regions of the brain. We conclude that hypophysiotropic TRH neurons contain functional TRs, and therefore, these neurons could be directly influenced by thyroid hormone. The relative paucity of TR alpha 2 in these cells could contribute to the selectivity of this population of TRH neurons to the effects of circulating levels of thyroid hormone.

Animals↗
PubMed1994

Bilateral progressive obliterative retinal vasculitis.

In this paper, 10 cases of a special type of retinal vasculitis are reported, which was characterized by progressive obliteration of vessels in both eyes, developed from the periphery to the posterior ploy, and was complicated by vitreous hemorrhage (5 eyes) and neovascular glaucoma (5 eyes) in later stage. The visual acuity was 0.05 in 10 eyes (50%). Argon laser photocoagulation seemed to be able to retard the natural course of the disease. Fundus changes, differential diagnosis and treatment etc are discussed in detail.

Adult↗
PubMed1994

[Myoperiosteocutaneous flap repair of trachea wall defects].

The experience of repairing the defect of trachea wall by using the sternocleidomastoid myoperiosteal or pectoral myoperiosteocutaneous flaps in 7 patients was reported. The operation was successful in all patients except one who complicated with local infection. The advantages and surgical technique were discussed in this paper. The periosteal flap with blood supplied muscle pedicle has good osteogenetic potency which is suitable to meet the specificity of tracheal repair. This method is simple, safe and reliable.

Aged↗
PubMed1994

[Bilateral progressive obliterative retinal vasculitis].

10 cases were reported with a special type of retinal vasculitis which was characterized by progressive obliteration of retinal blood vessels from peripheral retinas to the posterior poles in both eyes. In the late stage of the disease, it was complicated by vitreous hemorrhage in 5 eyes, neovascular glaucoma in 5 eyes, etc. The visual acuities of 10 eyes (50%) were < or = 0.05. It seems that argon laser photocoagulation can delay its natural course. Its fundus changes, fluorescein angiographic findings, differential diagnosis and treatment were discussed.

Adult↗
PubMed1994

[Single calcium channel analysis and electron spin resonance (ESR) spectral study on the myocardial effects of ginsenoside Rb2].

Based on the patch clamp technique, the effect of ginsenoside Rb2 on the single channel activity of Ca2+ was observed through the single ventricular myocytes of Wistar rats. Electron spin resonance was used to measure the free radical contents of cultured cardiomyocytes. It is proved that Rb2 can inhibit the activities of single calcium channel and significantly antagonize the increase of free radical contents induced by xanthine-xanthine oxidase.

Animals↗
PubMed1994

[Restriction digestion of two kind of baculoviruses and the location of their p10 genes].

The length of SeNPV and LsNPV genomes DNA were calculated to be 133kb and 164kb respectively, according to digestion with 5-8 restriction endonuleases. In order to map p10 gene in Baculoviruses DNA by pure probe, two probe vectors, pAcHP106 and pAcEP102, were constructed with 3'-0. 18kb and 3'-0. 18kb + 5'-0.24kb (coding sequence and promoter) from AcNPV p10 gene. The p10 genes of both baculoviruses, SeNPV and LsNPV, are located with 0.18kb and 0.42kb probes produced by random primer labeling.

Amino Acid Sequence↗
PubMed1994

[Near-total laryngectomy in the treatment of advanced laryngeal and hypopharyngeal carcinoma].

Near-total laryngectomy was first introduced by RB Pearson in 1980. In this report, 14 cases (T3, T4 laryngeal cancer 10 cases, pyriform fossa 3, cervical esophagus 1) treated with near-total laryngectomy. The speech function was obtained in 12/14 (85.7%) within 2 to 5 weeks, all cases had good swallowing. 2-year survival rate is 78.6%. The authors believed that such surgical technic is most indicated in the cases when regular partial laryngectomy can not be performed and in elderly cases who would have the risk with partial laryngectomy.

Aged↗
PubMed1993

High-affinity chimeric anti-(colorectal carcinoma) antibody correlated to enhanced tumor targeting in biodistribution and imaging.

The genetically engineered chimeric cB72.3m4 and cB72.3m12 antibodies recognize the same tumor-associated TAG72 antigen. The high-affinity cB72.3m4 antibody had an approximately 18-fold higher affinity constant for the TAG72 antigen than the low-affinity cB72.3m12 antibody. The relationship between antibody affinity and tumor targeting was studied by using these two antibodies. In biodistribution and imaging studies in athymic mice bearing LS174T human colon cancer xenografts, the radiolabelled high-affinity cB72.3m4 antibody was rapidly cleared from the blood, whereas the low-affinity cB72.3m12 antibody had slower blood clearance. The data showed that the high-affinity cB72.3m4 antibody appeared to localize more in tumors (based on tumor:normal-tissue ratios) than did the low-affinity cB72.3m12 antibody, and enhanced the target-to-nontarget image contrast. This study provides evidence that the high-affinity chimeric antibody cB72.3m4 may be useful in both immunodetection and immunotherapy of cancer.

Animals↗
PubMed1993

The tyrosine residue at position 97 in the VH CDR3 region of a mouse/human chimeric anti-colorectal carcinoma antibody contributes hydrogen bonding to the TAG72 antigen.

One amino acid, tyrosine at position 96 and 97 in the VH CDR3 region of a mouse/human chimeric anti-TAG72 antibody cB72.3m4 was substituted by the phenylalanine residue and by a number of amino acids from different amino acid groups by the site-directed mutagenesis technique. The expression vector mpSV2neo-EP1-Vm11-16C1 containing mutant VH region fragments (Vm11-16) as well as the immunoglobulin enhances (E), promoter (P1) and the human genomic C1 region fragments, were transfected into a heavy-chain-loss mutant cell line B72.3Mut(K), respectively. Mutant chimeric cB72.3m11-16 antibodies were purified from the transfectant supernates and compared based upon their binding affinity for the TAG72 antigen relative to that of the original cB72.3m4 antibody. The data showed that a single amino acid substitution of tyrosine by phenylalanine and a number of amino acids including serine, asparagine, histidine and arginine at position 97 in the VH CDR3 region all resulted in approximate 18-fold lower binding affinity, whereas the substitution of tyrosine by phenylalanine at position 96 in the VH CDR3 region did not affect the binding affinity of the cB72.3m4 antibody. This suggests that the tyrosine residue at position 97 in the VH CDR3 region is in a contact position in the B72.3/TAG72 antibody/antigen interaction, and that the terminal hydroxyl group of the position 97 tyrosine side-chain contributes hydrogen bonding to the TAG72 antigen, whereas the position 96 tyrosine side-chain does not.

Animals↗
PubMed1993

Recombinant bifunctional molecule FV/IFN-gamma possesses the anti-tumor FV as well as the gamma interferon activities.

Recombinant DNA techniques were used to clone, construct and express the bifunctional molecule FV/IFN-gamma. The FV/IFN-gamma is a single-chain 42KD fusion protein expressed in E. coli under control of the strong T7 bacteriophage promoter in the expression vector pT7-7-FV-IFN-gamma. The fused gene fragment FV-IFN-gamma containing a single-chain anti-TAG72 FV gene fragment as well as the human recombinant cDNA fragment of IFN-gamma molecule. The renatured soluble form of FV/IFN-gamma was purified from E. coli inclusion bodies using HTPT chromatography. The yield of this fusion protein was estimated at 10mg/L. Our data showed that the FV/IFN-gamma molecule retained the TAG72 antigen-binding specificity and the IFN-gamma activity as measured in ELISA, Western blotting and up-regulation of CEA expression by IFN-gamma. Therefore, it may prove to be useful in targeting the biological effect of IFN-gamma to tumor cells and stimulating its immune destruction.

Antigens, Neoplasm↗
PubMed1993

Effects of hypoxia on oligodendrocyte signal transduction.

We have previously established that 21-day-old postnatal rat oligodendrocytes, maintained in monolayer culture and subjected to 6 h of hypoxia, show reversible inhibition of synthesis of alpha-hydroxy fatty acid and myelin basic protein but a dramatic induction of a 22-kDa protein, suggesting that this is a good model to study the mechanism of CNS demyelination caused by hypoxic injury. We now report that hypoxia also dramatically inhibits the basal protein kinase C-mediated phosphorylation of myelin basic protein and myelin 2',3'-cyclic nucleotide phosphohydrolase by 80%, but that the inhibition of phosphorylation can be reversed by addition of a protein kinase C activator, phorbol 12-myristate 13-acetate. The mechanism of action appears to involve the uncoupling of signal transduction at a site before phospholipase C, because hypoxia did not affect protein kinase C activity or its translocation to the membrane fraction. The most potent activator of phospholipase C (as measured by inositol phosphate release) was carbachol (muscarinic M1 receptor agonist), followed by L-phenylephrine (alpha 1-adrenergic receptor agonist) in normal oligodendrocytes. Excitatory amino acids and histamine were ineffective. Hypoxia for 6 h completely inhibited both muscarinic and alpha 1-adrenergic receptor-mediated inositol monophosphate release but did not affect phospholipase D-coupled phosphatidylethanol production in response to carbachol. We therefore conclude from this and earlier work that early, reversible changes in oligodendrocyte metabolism result not simply from ATP depletion, but may specifically target GTP binding protein-mediated processes.

Animals↗
PubMed1993

Bacillus subtilis transcription regulator, Spo0A, decreases alkaline phosphatase levels induced by phosphate starvation.

Alkaline phosphatase (APase) is induced as a culture enters stationary phase because of limiting phosphate. The results presented here show that expression of APase is regulated both negatively and positively. PhoP, a homolog of a family of bacterial transcription factors, and PhoR, a homolog of bacterial histidine protein kinases, are required for induction of APases when phosphate becomes limiting. The induction period lasts 2 to 3 h, after which the rate of APase accumulation is decreased. Mutant strains defective in the Spo0A transcription factor failed to decrease APase production. The consequent hyperinduction of APase in a spo0A strain was dependent on phoP and phoR. spo0B and spo0F strains also overexpressed APase, suggesting that phosphorylated Spo0A is required for repression of APase. An abrB mutant allele in the presence of the mutant spo0A allele in these strains did not significantly change the APase hyperinduction phenotype, demonstrating that Spo0A repression of abrB expression is not the mechanism by which Spo0A-P regulates APase expression. Our previous report that spo0A mutants do not express APases is in conflict with the present data. We show here that the previously used mutants and a number of commonly used spo0 strains, all of which have an APase deficiency phenotype, contain a previously unrecognized mutation in phoR.

Alkaline Phosphatase↗
PubMed1993

Immunocytochemical delineation of thyroid hormone receptor beta 2-like immunoreactivity in the rat central nervous system.

The thyroid hormone receptors (TR) are nuclear proteins that include TR alpha and TR beta subtypes, each encoded by a separate gene. Both TR alpha and TR beta give rise to several isoforms of which three, TR alpha 1, TR beta 1, and TR beta 2 bind T3 and mediate the action of thyroid hormone. Although TR beta 2 was initially thought to be confined to the anterior pituitary, we recently observed small quantities of TR beta 2 messenger RNA (mRNA) by polymerase chain reaction analysis of discrete hypothalamic regions. To further examine the distribution of TR beta 2 in the brain, we performed immunocytochemical studies using a highly specific antiserum to TR beta 2, raised against a unique amino acid sequence (TR beta 2[131-145]) that is not present in the other known TRs. This antiserum immunoprecipitated TR beta 2 but not TR alpha 1 or TR beta 1. Immunoreactive TR beta 2 was widely distributed throughout the brain and primarily localized to the cell nucleus. Particularly intense immunostaining was present in the cerebral cortex, cerebellum, and hypothalamus, including regions where TR beta 2 mRNA had not previously been identified. In addition, immunoprecipitation of nuclear extracts with anti-TR beta 2 reduced total T3 binding capacity by approximately 20%, suggesting that immunoreactive TR beta 2 comprises a substantial portion of the total content of nuclear thyroid hormone binding proteins. These studies demonstrate that immunoreactive TR beta 2 is more widely represented in the central nervous system than previously suspected and may play an important role in mediating the action of T3 in many different regions of the brain. The finding of TR beta 2-like material could be due to a disproportionately high ratio of the TR beta 2 translation product and its mRNA in certain regions of the brain, or could indicate the existence of a novel TR beta 2-related protein that is important for T3 binding.

Amino Acid Sequence↗