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Biomedical subjects

Y T Yu

Publications and source records attributed to Y T Yu.

At least 55 records · Page 3Linked to original sources
PubMed1993

Clinical trials for removal of bilirubin by high-capacity nonionic adsorbent.

To remove bilirubin from patients with hyperbilirubinemia, nonionic macroporous adsorbent NK-110 was tailor-made from styrene and divinyl benzene at Nankai University. Five patients were perfused through shunts filled with 500 ml of the above adsorbent. After 2 h of hemoperfusion, total bilirubin decreased within the range of 22-51%. During the treatment, no noticeable changes in electrolytes, urea nitrogen, serum glutamicpyruvic transaminase (SGPT), TTT, and amino acid concentrations were observed. Platelet depletion was satisfactory. Hemoglobin, white cell count, globulin, and albumin showed no remarkable changes. The nonionic adsorbent shows a high efficacy for bilirubin removal and has a great potential for future clinical applications.

Adsorption↗
PubMed1993

hMEF2C gene encodes skeletal muscle- and brain-specific transcription factors.

The myocyte enhancer-binding factor 2 (MEF2) site is an essential element of many muscle-specific enhancers and promoters that binds nuclear proteins from muscle and brain. Recently, we have cloned a family of MEF2 transcription factors produced by two genes that, at the mRNA level, are broadly expressed and produce tissue-specific isoforms by posttranscriptional processes (Y.-T. Yu, R. E. Breitbart, L. B. Smoot, Y. Lee, V. Mahdavi, and B. Nadal-Ginard, Genes Dev. 6:1783-1798, 1992). Here, we report the isolation and functional characterization of cDNA clones encoding four MEF2 factors derived from a separate gene that we have named hMEF2C. In contrast to those of the previously reported genes, the transcripts of the hMEF2C gene are restricted to skeletal muscle and brain. One of the alternate exons is exclusively present in brain transcripts. The products of this gene have DNA-binding and trans-activating activities indistinguishable from those of the previously reported MEF2 factors. The hMEF2C gene is induced late during myogenic differentiation, and its expression is limited to a subset of cortical neurons. The potential targets for this transcription factor in a subset of neurons are not known at this time. The strict tissue-specific pattern of expression of hMEF2C in comparison with the more ubiquitous expression of other MEF2 genes suggests a different mode of regulation and a potentially important role of hMEF2C factors in myogenesis and neurogenesis.

Alternative Splicing↗
PubMed1992

Interaction of U6 snRNA with a sequence required for function of the nematode SL RNA in trans-splicing.

Nematode trans-spliced leader (SL) RNAs are composed of two domains, an exon [the 22-nucleotide spliced leader] and a small nuclear RNA (snRNA)-like sequence. Participation in vitro of the spliced leader RNA in trans-splicing reactions is independent of the exon sequence or size and instead depends on features contained in the snRNA-like domain of the molecule. Chemical modification interference analysis has revealed that two short sequence elements in the snRNA-like domain are necessary for SL RNA activity. These elements are sufficient for such activity because when added to a 72-nucleotide fragment of a nematode U1 snRNA, this hybrid RNA could participate in trans-splicing reactions in vitro. One of the critical sequence elements may function by base-pairing with U6 snRNA, an essential U snRNA for both cis- and trans-splicing.

Animals↗
PubMed1992

Sequence requirements for maturation of the 5' terminus of human 18 S rRNA in vitro.

Creation of the mature 5' terminus of human 18 S rRNA in vitro occurs via a two-step processing reaction. In the first step, an endonucleolytic activity found in HeLa cell nucleolar extract cleaves an rRNA precursor spanning the external transcribed spacer-18 S boundary at a position 3 bases upstream from the mature 18 S terminus leaving 2',3'-cyclic phosphate, 5' hydroxyl termini. In the second step, a nucleolytic activity(s) found in HeLa cell cytoplasmic extract removes the 3 extra bases and creates the authentic 5'-phosphorylated terminus of 18 S rRNA. Here we have examined the sequence requirements for the trimming reaction. The trimming activity(s), in addition to requiring a 5' hydroxyl terminus, prefers the naturally occurring adenosine as the 5'-terminal base. By a combination of deletion, site-directed mutagenesis, and chemical modification interference approaches we have also identified a region of 18 S rRNA spanning bases +6 to +25 (with respect to the mature 5' end) which comprises a critical recognition sequence for the trimming activity(s).

Base Sequence↗
PubMed1992

Human myocyte-specific enhancer factor 2 comprises a group of tissue-restricted MADS box transcription factors.

The MEF2 site is an essential element of muscle enhancers and promoters that is bound by a nuclear activity found, so far, only in muscle and required for tissue-specific transcription. We have cloned a group of transcription factors from human muscle that are responsible for this activity: They are present in muscle-specific DNA-binding complexes, have a target sequence specificity identical to that of the endogenous activity, and are MEF2 site-dependent transcriptional activators. These MEF2 proteins comprise several alternatively spliced isoforms from one gene and a related factor encoded by a second gene. All share a conserved amino-terminal DNA-binding domain that includes the MADS homology. MEF2 transcripts are ubiquitous but accumulate preferentially in skeletal muscle, heart, and brain. Specific alternatively spliced isoforms are restricted to these tissues, correlating exactly with the presence of endogenous MEF2 activity. Furthermore, MEF2 protein is detected only in skeletal and cardiac muscle nuclei and not in myoblast and nonmuscle cells. Thus, post-transcriptional regulation is important in the generation of tissue-specific MEF2 activity. Cardiac and smooth, as well as skeletal, muscles contain functionally saturating levels of MEF2 trans-activating factors that are absent in nonmuscle cells. Moreover, MEF2 is induced in nonmuscle cells by MyoD; however, MEF2 alone is insufficient to produce the full muscle phenotype. Implications for the molecular mechanisms of myogenesis are considered.

Amino Acid Sequence↗
PubMed1992

[Treatment of chronic gastritis with traditional Chinese medicine--yingwei tablet].

A prospective controlled study on the treatment of 60 cases chronic gastritis with TCM Yingwei tablet as well as Sucrafati and Doperidone tablets from Oct. 1990 to Sep. 1991 were done. 30 patients in each group. The cases in treated group took Yingwei tablet while that in control group took Sucrafati and Doperidone tablets. Before and after treatment, the patients were examined by gastroscope, pathology and Helicobacter pylori. The results showed that total effective rate, the gastroscopically effective rate, the pathological cure rate, the cure rate of gastric mucosa atrophy and the effective rate of bacteriocidal effect against Helicobacter pylori in treated group and control group was 96.7% and 73.3%; 80% and 70%; 36.7% and 20%; 38% and 9%; 60% and 23.0%, respectively, all of the above-mentioned differences between the two groups was significant (P < 0.05-0.01). Therefore Yingwei tablet is an effective drug for various kind of chronic gastritis.

Adult↗
PubMed1992

Absence of genomes of DNA tumor viruses and expression of oncogenes and growth factors in two esophageal carcinoma cell lines of Chinese origin.

To study the oncogenesis of human esophageal carcinoma, the presence of DNA sequences homologous to several DNA tumor viruses and the expression of oncogenes and growth factor genes were examined in two esophageal carcinoma cell lines of Chinese origin, CE48T/VGH and CE81T/VGH. Southern blot analyses failed to detect sequences homologous to hepatitis B virus (HBV), Epstein-Barr virus (EBV), herpes simplex virus type 2 (HSV-2), cytomegalovirus (CMV) or human papilloma virus (HPV) genomes. Northern blot analyses revealed that c-myc, c-src, c-H-ras, c-abl, c-sis, and p53 genes were expressed. In addition, transcripts of transforming growth factor alpha (TGF alpha), TGF beta, and platelet derived growth factor A (PDGF A) genes were detected. These studies suggest that DNA tumor viruses may not be involved in the carcinogenesis of esophageal carcinoma. However, cooperation among different oncogenes and the production of growth factors may play an important role in that carcinogenesis.

Carcinoma↗
PubMed1990

A site in the T4 bacteriophage major head protein gene that can promote the inhibition of all translation in Escherichia coli.

The cryptic DNA element, e14, synthesizes a protein, Lit, which can inhibit gene expression late in T4 bacteriophage development. This inhibition is due to the interaction between the Lit protein and a short region, the gol region, within gene 23, the major head protein gene of phage T4. We have constructed plasmids in which the gol region is transcribed from the lac promoter and fused translationally and transcriptionally to lacZ and cat (chloramphenicol acetyltransferase). These fusion plasmids were used to demonstrate that, in the presence of Lit protein, the gol region inhibits the expression of genes downstream in the same transcription unit. This local inhibition does not require the gene 23 polypeptide from the gol region. In addition, inducing the transcription and translation of the gol region in the presence of Lit protein causes an immediate global inhibition of all translation in Escherichia coli. This global inhibition does require the gene 23 polypeptide. No more than 75 base-pairs of DNA from the gol region are required for both the local and global inhibitions. The gol region sequence contains a short dyad symmetry. However, it is the sequence of bases in the region of dyad symmetry and not the ability to form a hairpin in the RNA that is required for gol region activity.

Amino Acid Sequence↗
PubMed1990

Advances of adsorbents for hemoperfusion in China.

Activated charcoal with various coating materials were screened and tested as adsorbents in hemoperfusion. Among them silicon rubber polyurethane, crosslinked agrose, polyvinyl acetate, polyhydroxy ethyl methacrylate showed good blood compatible properties. Various types of resins and carbonized resins with different functional groups, and structures were tested for the adsorption of small molecules i.e. creatinine, barbiturates, middle molecules i.e. VitB12, inulin, cytochrome C and large molecules i.e. unconjugated bilirubin. High adsorption capacities were obtained and uncoated carbonized resins showed satisfactory blood compatible properties. NK-107 a macroporous, non-coated resin is now being manufactured and successfully used clinically on patients for acute detoxification of hypnotic drugs. Polysaccharide dialdehyde and polystyrene derivatives etc. were used for the removal of urea, ammonia, potassium and phosphorus. DNA immune adsorbents were prepared for systemic lupus erythematosus therapy.

Adsorption↗
PubMed1989

Interaction of nuclear proteins with a positive cis-acting element of rat embryonic myosin heavy-chain promoter: identification of a new transcriptional factor.

A DNA fragment of the rat embryonic myosin heavy-chain promoter (MHCemb) has been found to specifically bind a nuclear factor (NFe) present in extracts prepared from mouse C2 myoblasts, myotubes, and HeLa cells. The nucleotide sequence of the binding site (BSe) has been identified as 5'-GTGTCAGTCA-3' and was located between -93 and -84. Transient expression studies on MHCemb promoter deletion constructs in C2 myoblasts and C2 myotubes suggested that NFe is a transcriptional factor. Deletion of the NFe-binding site resulted in four- to sixfold and twofold reduction of promoter activity in C2 myotubes and C2 myoblasts, respectively. Furthermore, point mutations at the BSe not only abolished the NFe-binding activity of the MHCemb promoter but also resulted in reduction of the promoter activity to levels similar to those of the deletion constructs in C2 myotubes, myoblasts, and Hela cells (four- to sixfold). Although BSe and the binding site of the recently identified transcriptional factors AP-1 and ATF share significant homology, the results from competition binding assays indicated that NFe is different from both AP-1 and ATF.

Animals↗
PubMed1989

Reactivity and stability improvement of immobilized glucose oxidase.

Glucose oxidase (GOD) was immobilized on agrose(a) by diazotization using p(beta-sulfate-ethylfonyl)aniline(SESA) as cross-linking agent, (b) by a new improved glutaraldehyde method and (c) by polyacrylamide entrapment. Results showed that GOD immobilized by the improved glutaraldehyde method had an activity of 10% and 100% higher than that by diazotization and entrapment method respectively. Catalase co-immobilized with GOD on agrose greatly enhanced the stability of GOD. Proteins such as hemoglobin(Hb), bovine serum albumin(BSA) and reducing agent i.e. VitC added during immobilization had the same effect but to a lesser extent.

Drug Stability↗
PubMed1988

A new DNA immune adsorbent for hemoperfusion in SLE therapy: a clinical trial.

This investigation studied the preparation and clinical trial of DNA immunoadsorbent for hemoperfusion in systemic lupus erythematosus (SLE) therapy. DNA was complexed with blue tetrazolium (BT), then mixed with collodion, and finally adsorbed on macroporous spherical polymeric adsorbent. The percentage of DNA thus immobilized was 98-98.5%, and no release was detected during hemoperfusion. A patient with severe SLE was treated with the above adsorbent in hemoperfusion. The patient was in coma, with high anti-DNA antibody and abnormal immune complex levels, which fell sharply from 56.34% to 0.8% after 2.5 h of whole-blood hemo perfusion. There were no major clinical complications, and 2 weeks later, her proteinuria level became normal and immune complex levels were sustained. She was then discharged from the hospital and has been in good health for more than 1 year.

Adult↗
PubMed1988

Simian virus 40 (SV40) T antigen binds specifically to double-stranded DNA but not to single-stranded DNA or DNA/RNA hybrids containing the SV40 regulatory sequences.

Simian virus 40 T antigen has been shown previously to bind specifically with high affinity to sites within the regulatory region of double-stranded simian virus 40 DNA. Using competition filter binding and the DNA-binding immunoassay, we show that T antigen did not bind specifically to either early or late single-stranded DNA containing these binding sites. Moreover, T antigen did not bind these sequences present in single-stranded RNA, RNA/RNA duplexes, or RNA/DNA hybrids. T antigen did, however, bind as efficiently to single-stranded DNA-cellulose as to double-stranded DNA-cellulose. This binding was nonspecific because it was independent of the presence of T-antigen-binding sites. The implications of these observations are discussed.

Antigens, Polyomavirus Transforming↗
PubMed1987

In vitro in vivo studies on removal of middle molecules by macroporous resins.

Various types of macroporous resin beads were screened for the adsorption of middle molecules in vitro. In order to obtain high adsorption capacity, the pore size of the resin should be large enough to allow diffusion of the middle molecules. The adsorption capacity of X-5 resin for Vitamin B12, inulin and cytochrome C was 35.3 mg/g, 1.2 mg/g and 42.9 mg/g respectively in vitro tests. Hemoperfusion with acute renal failure rat model showed good clearance (0.35 +/- 0.25) with X-5 resin for middle molecules.

Acute Kidney Injury↗
PubMed1986

Structure and function of the S1 nuclease-sensitive site in the adenovirus late promoter.

We analyzed an S1 nuclease-sensitive site present in supercoiled, but not linear, recombinant plasmids containing the adenovirus late promoter. S1 nicking was detected on both strands, primarily in the TATA box. Analysis of deletion mutants showed that sequences upstream of -47 and downstream of -12 are not required for S1 cutting. However, a number of different base substitution mutations in stretches of G residues upstream and/or downstream of the TATA box were sufficient to eliminate S1 cutting. When the transcriptional activities of these mutant promoters were assayed in vivo, six of seven mutants lacking the ability to form the S1-sensitive structure showed no reduction in transcriptional potential. In fact, several showed increased promoter activities. These data show that the S1 nuclease cutting site in the adenovirus late promoter has precise nucleotide sequence requirements for its formation. However, the ability of recombinant plasmids to adapt this conformation in vitro is not necessary for such plasmids to serve as templates for transcription in vivo.

Adenoviridae↗
PubMed1986

Removal of unconjugated bilirubin by macroreticular resin in hemoperfusion.

Macroporous polystyrene and polyvinylpyridine beads with quaternary ammonium and tertiary groups were tailor-made for the adsorption of unconjugated bilirubin. In vitro studies in order to obtain high adsorption capacity, the synthesized macroporous resin should have an average pore size of about 160 A and with surface area as large as possible. As the crosslinking of the resin increased from 4%-40% the amount of bilirubin adsorbed increased from 0.17 mg/g to 2.0 mg/g. Resins containing strong basic groups have higher adsorption capacities than their corresponding weak base groups. Adsorption mechanism studies showed that both chemical and physical adsorption took place. Adsorption of bilirubin in plasma was some what lower than in buffer solution.

Adsorption↗
PubMed1984

Generation and functional analyses for base-substitution mutants of the adenovirus 2 major late promoter.

The function of guanosine residues surrounding the TATA box of the adenovirus 2 major late promoter (MLP) in promoting efficient transcription initiation and in selecting a specific transcription start site in vitro has been examined. Multiple and single base substitutions (G----A) were generated in this region (from -63 to +25 relative to the cap site, +1) of the MLP. The promoter activities of the wild type and 21 mutants were assayed in an in vitro transcription system using whole cell extract (WCE) prepared from HeLa cells. The results suggest that the strings of G residues immediately adjacent to the TATA box are not required for full promoter activity in vitro. These G residues also appear not to be involved in the selection of a specific transcription start site by RNA polymerase II in vitro, since the identical cap site was used by wild-type and mutated MLP's. However, two G residues (-55 and -57) were identified as part of an upstream promoter element: a G----A transition at either -55 or -57 resulted in a 2.6 fold reduction in promoter activity. However, neither single nor double G----A transitions at -62 and -63 had an effect on promoter activity.

Adenoviruses, Human↗