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Biomedical subjects

C W Yu

Publications and source records attributed to C W Yu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Metal-induced metallothionein gene expression can be inactivated by protein kinase C inhibitor.

The effects of protein kinase C (PKC) inhibitors on the metallothionein (MT) gene expression induced by metals were investigated. When PKC inhibitor (H7 or chelerythrine) was administered to Cd resistant, MT gene-amplified Chinese hamster ovary (CdR) cells, the induction of MT mRNA by Cd or Zn was blocked. Treating the CdR cells with a PKA-specific inhibitor, HA1004, did not cause an inhibition of metal-induced MT gene transcription. The inhibitory effect was effectuated by adding inhibitors within 40 min of exposing the cells to Cd. Apparently, AP1 was not involved in this down-regulatory effect of PKC inhibitor on MT gene expression since the inducibility of MT promoter was blocked by H7 even in the absence of the AP1-binding sequence. For Cd-treated cells, Cd accumulation in the cell was similar with or without H7 treatment. However, H7 markedly reduced cellular Zn accumulation when the cells were treated with Zn. Cycloheximide treatment increased the level of MT mRNA. This elevation can also be blocked by treating the cell with PKC inhibitor. Results in this study suggest that PKC participates in the process of metal-induced MT gene expression.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Propofol attenuates ischemia-reperfusion injury in the isolated rat heart.

UNLABELLED: The purpose of this study was to examine the direct effects of propofol on ischemia-reperfusion injury using an isolated Langendorff rat heart preparation. Hearts were perfused with Krebs-Henseleit (K-H) solution (control); intralipid; or 10, 30, and 100 microM propofol. Hearts were rendered globally ischemic for 25 min, then reperfusion was begun with K-H solution for 30 min. Treatment with 100 microM propofol delayed the onset of contracture during ischemia compared with control or intralipid treatments (6.4 +/- 2.1 vs 4.4 +/- 1.4 or 4.1 +/- 0.7 min, respectively; P < 0.05). During reperfusion, 100 microM propofol increased coronary flow and reduced lactate dehydrogenase release compared with control or intralipid treatments. After 30 min of reperfusion, left ventricular developed pressure (LVDP) returned to 55 and 76 mm Hg in the 30 and 100 microM propofol-treated groups, respectively, whereas LVDP was 39 mm Hg in the control group. The hearts treated with 100 microM propofol showed significantly lower left ventricular end-diastolic pressure compared with the control or intralipid groups 30 min after reperfusion (29 +/- 13 vs 48 +/- 5 or 48 +/- 11 mm Hg, respectively; P < 0.05). In histological evaluation, control and intralipid hearts had increased injury severity scores compared with hearts treated with 100 microM propofol (1.8 +/- 0.9 and 1.7 +/- 0.8 vs 1.0 +/- 0.7, respectively; P < 0.05). In conclusion, we suggest that propofol administered before and during global myocardial ischemia has cardioprotective effects on ischemia-reperfusion injury. IMPLICATIONS: It is important to protect the heart from injury by ischemia and reperfusion. The current study demonstrates that in the isolated rat heart, propofol attenuates mechanical, biochemical, and histological changes causes by ischemia and reperfusion.

Anesthetics, Intravenous↗
PubMed1995

Octopus S-crystallins with endogenous glutathione S-transferase (GST) activity: sequence comparison and evolutionary relationships with authentic GST enzymes.

S-Crystallin is a major protein present in the lenses of cephalopods (octopus and squid). To facilitate the cloning of this crystallin gene, cDNA was constructed from the poly(A)+ mRNA of octopus lenses, and amplified by PCR for nucleotide sequencing. Sequencing of 10 of 15 positive clones coding for this crystallin revealed three distinct S-crystallin isoforms with 61-64% identity in nucleotide sequences and 42-58% similarity in amino acid sequences when compared with homologous crystallins in squid lenses. These charge-isomeric crystallins also show between 26 and 33% amino acid sequence identity to four major classes of glutathione S-transferase (GST), a major detoxification enzyme present in most mammalian tissues. For further analysis, expression of one of the S-crystallin cDNAs was carried out in the bacterial expression system pQE-30, and the S-crystallin protein produced in Escherichia coli was purified to homogeneity to determine the enzymic properties. We found that the expressed octopus S-crystallin possessed much lower GST activity than the authentic GSTs from other tissues. Sequence comparison and construction of phylogenetic trees for S-crystallins from squid and octopus lenses and various classes of GSTs revealed that S-crystallins represent a multigene family which is structurally related to Alpha-class GSTs and probably derived from the ancestral GST by gene duplication and subsequent multiple mutational substitutions.

Amino Acid Sequence↗
PubMed1995

Cloning and characterization of the 5'-flanking region of metallothionein-I gene from Chinese hamster ovary cells.

The 5'-flanking region of the Chinese hamster ovary metallothionein-I gene (MT-I) was isolated and sequenced. This region contains several cis-regulatory sequences, including metal-responsive element (MRE), AP1-binding site, Sp1-binding site and glucocorticoid-responsive element (GRE). These elements are located within 250 bases upstream of the transcription initiation site, as determined by primer extension. This region was fused with a reporter gene that could be activated by the challenge of cadmium only when the MREs were present. Thus, the isolated DNA is the promoter region of the CHO MT-I gene.

Animals↗
PubMed1993

Facile cloning and sequence analysis of goose delta-crystallin gene based on polymerase chain reaction.

To facilitate the cloning of delta-crystallin gene, the product of which is a major lens protein present in the avian and reptilian lenses, polymerase chain reaction (PCR) was employed to amplify cDNAs constructed from the poly(A)+RNA of goose lenses. The PCR product was then subcloned into pUC19 vector and transformed in E. coli strain JM109. Plasmids purified from the positive clones were prepared for nucleotide sequencing by dideoxynucleotide chain-termination method. Sequencing several clones containing 1.4 kb DNA inserts encoding delta-crystallin constructed a complete and unambiguous full-length reading frame of 1401 base pairs covering a deduced protein sequence of 465 amino acids excluding the universal translation-initiating methionine. The goose delta-crystallin shows 88, 94, 88 and 69% sequence identity to pigeon delta, duck delta 2, chicken delta 1 crystallins and human argininosuccinate lyase respectively. It is also shown that, similar to duck delta 2 and in contrast to pigeon delta crystallin, goose delta-crystallin appears to possess high argininosuccinate lyase activity despite the fact that a highly homologous structure is shared among these homologous proteins. Structural analysis and comparison of these closely related delta-crystallin homologues with or without enzymatic activity should be of value in unraveling the intriguing evolutionary process leading to the development and evolution of active enzymatic crystallins in the lenses of certain avian species.

Amino Acid Sequence↗
PubMed1993

N-hexane neuropathy in offset printers.

In an offset printing factory with 56 workers, 20 (36%) developed symptomatic peripheral neuropathy due to exposure to n-hexane. Another 26 workers (46%) were found to have subclinical neuropathy. The initial change in the nerve conduction study was reduced amplitude of the sensory action potentials, followed by reduced amplitude of the motor action potentials, reduction in motor conduction velocities and increase in distal latencies. These changes indicate primary axonal degeneration with secondary demyelination. Sural nerve biopsy in a severe case showed giant axonal swellings due to accumulation of 10nm neurofilaments, myelin sheath attenuation and widening of nodal gaps. The development of neuropathy bore no direct relationship to the duration of exposure, hence factors such as individual susceptibility may be important. Optic neuropathy and CNS involvement were uncommon and autonomic neuropathy was not encountered.

Adolescent↗
PubMed1991

Molecular cloning of Chinese hamster metallothionein II gene and its 5' flanking region.

A genomic DNA clone containing Chinese hamster metallothionein II (MTII) gene and its 5' flanking region was isolated from Cd resistant Chinese hamster ovary (CHO) cells. DNA sequence analysis showed that there are three exons and two introns in the structure of the MTII gene. Further characterization of the 5' flanking region reveals the possible transcription initiation site, metal responsive element and basal-level enhancer sequence. Putatively, this is the promoter region of CHO MTII gene.

Animals↗
PubMed1990

Surface hydrophobicity of gastric mucosa in peptic ulcer disease. Relationship to gastritis and Campylobacter pylori infection.

The hydrophobicity of biopsy specimens of gastric mucosa in 228 dyspeptic subjects undergoing diagnostic endoscopy was assessed by measuring the plateau-advancing contact angle of saline drops using a goniometer. Subjects with duodenal ulcers (n = 49) and gastric ulcers (n = 17) had significantly lower mean contact angles than controls (n = 124) without ulcer (57 degrees in duodenal ulcer, 59 degrees in gastric ulcer vs. 66 degrees in controls; p less than 0.0001). There was no change in contact angle after healing with H2-receptor antagonists by comparison with pretreatment (59 degrees vs. 56 degrees for duodenal ulcer, n = 15; 57 degrees vs. 59 degrees for gastric ulcer, n = 5). Controls with gastritis had lower contact angles than those without (61 degrees, n = 50, vs. 70 degrees, n = 63; p less than 0.0001). The presence of Campylobacter pylori was associated with a significant decrease in contact angle in controls (59 degrees, n = 39, vs. 70 degrees, n = 75; p less than 0.0001).

Biopsy↗
PubMed1983

Specific terminal DNA replication sequence of X chromosomes in different tissues of a live-born triploid infant.

Using the thymidine pulse method, DNA replication kinetics were studied on cells derived from cartilage, gonad, lymphocytes, and skin of a live-born triploid (69,XXY) infant with typical clinical findings. Replication studies showed that 3% of the lymphocytes had one early and one late replicating X, and 97% of the lymphocytes, and cartilage, gonad, and skin cells had two early replicating X's. Asynchronous DNA replication between the two early replicating X's was observed in all tissues (range 25-40%). The predominant terminal replication sequence of X chromosomes from chondrocytes, gonad, and skin fibroblast differed from that of the lymphocytes. Thus, a tissue-specific DNA replication pattern of the early-replicating X chromosome may be present. In every tissue, the last band to complete DNA replication was Xq21. Polymorphisms of metaphase chromosomes of parents and the patient were studied by Q-banding. The possible origin of the extra haploid set of chromosomes is discussed.

DNA Replication↗
PubMed1982

DNA replication sequence in a dicentric (functionally monocentric) X chromosome formed by the joining of two X chromosomes at region p22.

In this study we used densitometry to evaluate DNA replication kinetics in a rearranged chromosome formed by the joining of two X chromosomes at region p22. No 45X mosaicism is present in peripheral blood or fibroblast cultures. The patient has primary amenorrhea, short stature, and gonadal dysgenesis. The sequence of replication in the majority of cells is p11, q11, q13, q22-24, q12, p22, q26, q28, q27, q25, and p21, q21. Thus p11 is the earliest region to replicate, and q21 is the last. In 66% of 127 cells analyzed, the replication pattern is asymmetric, and bands q12, q26, and q28 are most likely to be out of phase on the two sides of the breakpoint. We find that band p22 has a delay of replication compared to an abnormal X derived from two X chromosomes joined at the q23 region previously reported by us. Structural rearrangement may therefore delay replication in the region of the break.

Adult↗
PubMed1981

Mosaic trisomy 19 syndrome.

A stillborn male infant with mosaic trisomy 19 (46,XY/47,XY,+19) is reported. The prenatal ultrasound revealed polyhydramnios, edema of the fetal head and abdominal ascites. The clinical features of the proband include hydrops, epicanthal fold, hypertelorism, flat nasal bridge, short nose, small mouth, low-set and malformed ears, narrow meati, short neck with excessive skin, short chest, protuberant abdomen, mild relative shortening of the proximal portion of the extremities, spoon-shaped nails, Simian lines and club feet. These features are compared to two earlier reports of trisomy 19q syndrome.

Abnormalities, Multiple↗
PubMed1981

Terminal deletion of the long arm of chromosome 4. Report of a case of 46, XY, del(4)(q31) and review of 4q- syndrome.

Using Q banding technique we recently identified a terminal deletion of the distal segment of the long arm of chromosome 4 in a male infant with multiple long arm of chromosome 4 in a male infant with multiple congenital anomalies. The breakpoint is at 4q31. The infant had hypertelorism, epicanthal folds, depressed nasal bridge, short nasal septum with upturned nose, bilateral open cleft lip and palate, retro- and micrognathia, low set, malformed ear, short neck, distally placed nipples, a sacral dimple, hypospadias, dysplastic nails, overriding toes, simian creases, patterns on interdigital and hypothenar areas, hypoplasia of gallbladder, and cardiac defects consisting of tricuspid atresia, left sided vena cava and anomalous aortic arch. This case is compared to the eight previously reported 4q- cases.

Abnormalities, Multiple↗
PubMed1980

Densitometric and visual measurements of human chromosome 21.

The finding of heteromorphisms in certain regions of human chromosomes is useful in chromosome identification, especially in the study of the origin of nondisjunction. Quantitation of heteromorphisms in the smaller human chromosomes is theoretically valuable but remains technically difficult. In this paper we evaluate two methods for quantitation of human chromosome 21--visual densitometric measurement of Q-banded 34-mm negatives. Thirteen parameters are defined for chromosome 21. We find three of them to show less variability between different measurements of the same cell and from cell to cell in the same individual: (1) the centromere index, defined as the ratio of length of the satellite, stalk, and short arm to the length of the satellite, stalk and short and long arms; (2) the ratio of length of the satellite to the length of the total heteromorphic region of the short arm; and (3) the ratio of the short arm intensity to the intensity of band q21. Another parameter, the ratio of satellite intensity to the intensity of band q21, is reproducible by visual measurement but not by densitometry. Based on these studies we conclude that densitometry is not necessarily better than visual quantitation of the heteromorphic region of chromosome 21.

Chromosome Banding↗
PubMed1980

Kinetics of DNA replication in a dicentric X chromosome formed by long arm to long arm fusion.

Utilizing the 5-bromo-deoxyuridine (BrdU) incorporation technique, we have recently studied the DNA replication kinetics in a dicentric X chromosome, formed by long arm-to-long arm fusion at band q23, for a 16-year-old black female with primary amenorrhea. The patient has a karyotype 45,X/46,X,dic(X)(q23). In the buccal smear the presence of X chromatin was found in 33% of the cells examined. The Barr bodies are large and 21% of them are bipartite. DNA replication studies were performed on the patient's lymphocytes by the thymidine pulse (T-pulse) method and confirmed comparatively by the BrdU pulse (B-pulse) method. The results indicate that the dicentric X chromosome is always late-replicating. The replication pattern is symmetric on both sides of the breakpoint and the replication sequence is, in order, p11, p22, q1(1-3), q22, q23, p21, and q21. This finding is comparable to those of other investigators and supports the theory that there exist two inactivation centers in the dicentric X chromosome, located on or near the q21 band.

Amenorrhea↗
PubMed1978

Break points in human chromosomes.

Break points of structural rearrangements of human chromosomes can be identified by banding techniques. The present study attempts to analyze the randomness and the distribution of the reported spontaneous break points in the human genome. Reports of break points in structural rearrangements of human chromosomes from the published sources up to October 1976 were analyzed. Based on the assumption that each unit length of band has an equal chance of being broken, chi2 tests show that positions of breakage are highly non-random; that is, breaks are more frequent in the negative band areas and in the centromeric and terminal regions. In double-break rearrangements the same band types tend to rejoin. The distribution of breaks is not proportional to the chromosome length. The longer chromosomes (i.e., 1--12, X) have a lower number of breaks per unit length, while the shorter chromosomes (i.e., 13--22, Y) have a greater number of breaks per unit length with the exception of chromosomes 4, 9, 10, 16, 17, 19, 20 and X. Out of the whole genome, chromosomes 9, 13, 18, 21, 22 and Y have the most breaks per unit length and chromosomes 16, 6, 2, 3 and 19 have the fewest. 18p11, 21q22 and Yp11 are the three bands with most frequent breaks. There are 53 bands where no breaks have been reported.

Chromosome Aberrations↗