Biomedical subjects

J M Yang

Publications and source records attributed to J M Yang.

At least 163 records · Page 9Linked to original sources

PubMed1994

A mutation in the V1 end domain of keratin 1 in non-epidermolytic palmar-plantar keratoderma.

Mutations in keratin 9 have been found in families with an epidermolytic form of palmar-plantar keratoderma (PPK). In another form of PPK (Unna-Thost type), epidermolysis is not observed histologically. We studied a pedigree with this non-epidermolytic form of PPK. By gene linkage analysis, the type I keratin locus could be excluded but complete linkage with the type II keratin region was found. Sequence analysis identified a single base change in the amino-terminal V1 variable subdomain of keratin 1, which caused a lysine to isoleucine substitution. This non-conservative mutation completely cosegregated with the disease and was not observed in 50 unrelated unaffected individuals. An examination of keratin amino-terminal sequences revealed a previously unreported 22-residue window in the V1 subdomain that is conserved among most type II keratins. The altered lysine is an invariant residue in this conserved sequence. Previously described keratin mutations affect the central regions important for filament assembly and stability, and cause diseases characterized by cellular degeneration or disruption. This is the first disease mutation in a keratin chain variable end region. The observation that it is not associated with epidermolysis supports the concept that the amino-terminal domain of keratins may be involved in supramolecular interactions of keratin filaments rather than stability. Therefore, hyperkeratosis associated with this mutation may be due to perturbations in the interactions of the keratin end domain with other cellular components.

Adult↗

PubMed1994

p53 protein overexpression and allele loss of p53 gene in gastric adenocarcinoma.

Gene alterations of p53 tumor suppressor gene such as point mutations, deletions or insertions occur in various human cancers. p53 protein overexpression was studied immunohistochemically in 80 gastric adenocarcinomas using an anti-human p53 antibody (Pab 1801) and the avidin-biotin-peroxidase technique. We have also analyzed allele loss of the human p53 gene in 54 cases of gastric adenocarcinoma using polymerase chain reaction and restriction fragment length polymorphism. p53 immunostaining was also demonstrated in 48 of 80 carcinomas (60%). Normal mucosa was always negative. No relation could be found between p53 immunostaining and the degree of differentiation. 21 of the 54 patients(39%) were informative for the p53 exon 4. In ten of these informative cases(47.6%), tumor DNAs showed allele loss when compared with nonmetastatic lymph node DNAs. Seven of the ten(70%) showed p53 immunoreactivity. These findings suggest that mutations of the p53 gene may play a role in the development of gastric adenocarcinoma and that allele loss of p53 frequently occurs in p53 immunoreactive gastric adenocarcinoma.

Adenocarcinoma↗

PubMed1994

Preferential sites in keratin 10 that are mutated in epidermolytic hyperkeratosis.

Epidermolytic hyperkeratosis (EH) is a rare autosomal dominant skin disease. Recent studies in our laboratory established genetic linkage to the type II keratin gene locus on chromosome 12q in one family with EH and identified a single amino acid mutation in keratin 1 that is responsible for the disease. Other point mutations in the keratin 1 or keratin 10 genes have now been reported in other patients with EH. We have examined a series of probands with EH in order to develop a catalog of mutations in keratin 10. Using direct sequencing of PCR-amplified genomic DNA, we have identified mutations in six families, in which five mutations occur in the beginning of the 1A rod domain of keratin 10-namely, two ARg10 to His, one Arg10 to Cys, and Asn8 to His, and a Tyr14 to Asp. This region contains highly conserved residues among all keratins. An additional mutation (Leu103 to Gln) was found in the conserved region late in the 2B rod domain in keratin 10. We developed several allele-specific assays to assess the frequency of these mutations in the general population. No evidence was found for the presence of such changes in unaffected individuals. In vitro functional assays performed with peptides corresponding to the 1A mutations in these families show severely diminished capacity to disaggregate preformed keratin intermediate filaments, in comparison with a wild-type control peptide. Results from this work support the hypothesis that the beginning of the 1A rod domain segment in keratin 10 contains preferential sites for disease-causing mutation in EH. This should be of considerable use when developing prenatal diagnostic tests and biologically based therapies for this disease.

Adult↗

PubMed1994

Functional role of phosphorylation of the multidrug transporter (P-glycoprotein) by protein kinase C in multidrug-resistant MCF-7 cells.

Multidrug resistance (MDR) is the phenomenon in which cells become resistant to several classes of structurally and functionally diverse drugs after exposure to a single cytotoxic agent. One form of MDR is associated with the overexpression of a large plasma membrane phosphoglycoprotein, P-glycoprotein, which acts as an energy-requiring drug transport pump. Protein kinase C may participate in MDR through posttranslational modification of P-glycoprotein. The purpose of this study is to critically evaluate P-glycoprotein as a substrate for protein kinase C and to determine whether phosphorylation leads to changes in drug transport. Protein kinase C from rat brain phosphorylated immunoprecipitated P-glycoprotein in a manner dependent on the activation of the exogenous kinase. Phorbol 12-myristate 13-acetate (PMA) increased the phosphorylation of P-glycoprotein 6-fold and selectively decreased the accumulation of vinblastine in resistant MCF-7/AdrR cells. PMA selectively decreased the cellular association of vinblastine with MDR cells after brief periods of incubation, but only after critical concentrations of drug were achieved. The actions of PMA did not require new synthesis of P-glycoprotein. PMA had similar effects in MCF-7/BC-19, a cell line transfected with a cDNA for P-glycoprotein. Staurosporine inhibited the effects of PMA on the phosphorylation of P-glycoprotein and on the accumulation of vinblastine. These data demonstrated that immunoprecipitated P-glycoprotein can be a substrate for protein kinase C, and that phosphorylation of the transporter is associated with significant changes in drug transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1994

Transvaginal color flow imaging in the follow-up of invasive gestational trophoblastic disease: a case report.

A case of invasive gestational trophoblastic disease after partial hydatidiform mole was presented in this study in which the diagnosis was made along with the treatment being monitored by means of transvaginal color Doppler ultrasound. In this case, the appearance or disappearance of vascular changes induced by invasive mole corresponded with serum beta human chorionic gonadotropin (beta-hCG) titer. Vascular changes displayed on color Doppler scanning may thus complement the application of hCG in postmolar pregnancy surveillance.

Adult↗

PubMed1993

Concurrence between the molecular overlap regions in keratin intermediate filaments and the locations of keratin mutations in genodermatoses.

By analysis of the existing available data, we have found that the locations of disease-causing mutations in epidermal keratin genes are distributed in a non-random manner. Most occur in exons 1 and 7 which encode the highly conserved 1A and 2B rod domain sequence regions of the keratin chains. Recent structural studies have suggested these sequences define an important overlap between neighboring molecules in keratin intermediate filaments. In order to better map the extent of these overlap sequences and concurrently to identify those sequences likely to be sensitive to mutations, we have used a series of synthetic peptides in an established filament disassembly assay. Thus residue positions 7-16 of the 1A and positions 107-117 of the 2B rod domain segments describe the extent of the molecular overlap window wherein mutations in keratin (and perhaps other) intermediate filaments are most likely to alter filament stability and lead to abnormalities.

Amino Acid Sequence↗

PubMed1993

Terfenadine (Seldane): a new drug for restoring sensitivity to multidrug resistant cancer cells.

In our efforts to identify clinically effective drugs for reversing multidrug resistance (MDR) mediated by P-glycoprotein, we tested terfenadine for anti-MDR activity because it appeared to sensitize a patient to doxorubicin and because it met structural requirements defined for this activity. Terfenadine sensitized MCF-7/ADR human breast cancer cells and L1210/VMDRC.06 murine leukemia cells to doxorubicin. At concentrations < or = 10 microM, terfenadine decreased the IC50 to doxorubicin by up to 25-fold against MCF-7/ADR cells and completely restored sensitivity to L1210/VMDRC.06 cells. The drug had no effect on the sensitive, parental cell lines and enhanced activity of other drugs affected by the MDR phenotype. Terfenadine was as potent as trans-flupenthixol, one of the most active modulators of MDR. The mechanism of action of terfenadine appeared to be due to inhibition of the function of P-glycoprotein since it augmented the accumulation of doxorubicin and inhibited the efflux of rhodamine 123 from MDR lines but had no effect on drug accumulation or efflux in sensitive cells. Terfenadine displaced azidopine from P-glycoprotein, but at concentrations higher than expected based on its overall potency. Since terfenadine is clinically available, has numerous structural derivatives available for study, and has a relatively low toxicity profile, this drug and drugs of its class should be evaluated for future clinical trials.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

Clonal chromosome abnormalities in human breast carcinomas. I. Twenty-eight cases with primary disease.

Cytogenetic analysis was performed on a selected series of short-term cultures of primary breast carcinomas from 28 patients. All patients had histopathologically confirmed malignancies, with the majority (25/28 cases) demonstrating infiltrating ductal carcinoma. All 28 cases evidenced clonal chromosome abnormalities, with 10/28 displaying only numeric aberrations, whereas 18/28 displayed clonal structural alterations. In near-diploid tumors the most common numeric changes were -17 and -19. However, trisomy 7 was the only numeric change in two near-diploid tumors. Structural chromosome alterations were primarily isochromosomes, apparent terminal deletions, and unbalanced non-reciprocal translocations. Chromosomes I (10/18-56%) and 6 (8/18-44%) were most frequently altered in this series. Breakpoints of clonal structural abnormalities were shown to cluster to several chromosome segments, including 1p22-q11, 3p11, 6p11-13, 7p11-q11, 8p11-q11, and 19q13. Analysis of the gain or loss of specific chromosome segments revealed that the most consistent tendency was over-representation of 1q, 3q, and 6p.

Adenocarcinoma, Mucinous↗

PubMed1993

Clonal chromosome abnormalities in human breast carcinomas. II. Thirty-four cases with metastatic disease.

Cytogenetic analysis was performed on a selected series of short-term cultures from 34 patients with documented metastatic breast carcinoma. The majority of tumor cells were hyperdiploid, with clonal structural alterations observed in 94% of patients (32/34). The most common numeric changes were -2, -15, and -18. Chromosome 20 was the most frequently over-represented (in near-3n tumors only). Clonal structural chromosome alterations included isochromosomes, terminal deletions, and, most frequently, unbalanced non-reciprocal translocations. Chromosomes most often involved in structural rearrangements included 1, 7, 11, and 6 (accounting for 24.7%, 10.3%, 9.1%, and 7.0% of breakpoints, respectively). When the breakpoints of clonal structural abnormalities were analyzed, they were shown to cluster to several chromosome segments, including 1p11-q21, 7pter, 11p12-q12, and 6q11-21. An analysis of the net gain or loss of specific chromosome segments was also performed, with the most consistent tendency observed being the over-representation of 1q, 6p, 7, and 11. The most frequent losses included 1p, 6q, 7, and 11q.

Adult↗

PubMed1993

Cytogenetics and clinical correlations in breast cancer.

We describe an ongoing study examining the relevance of cytogenetic changes in primary and metastatic breast cancer. Tumors samples from breast cancer patients are karyotype using G-banding techniques, and all chromosomal findings, including the presence of structural and numeric clonal abnormalities, are documented in a dynamic patient data base. Information on essential clinical characteristics is collected, and patients are followed longitudinally for disease recurrence, progression, and survival. Statistical analyses will examine potential correlations between specific abnormalities and clinical features of the disease, and survival differences between patients will be examined as a function of karyotypic differences. We anticipate that this research will provide insights on the natural history of breast cancer and help direct the search for the underlying molecular mechanisms of tumor genesis and progression.

Adult↗

PubMed1993

Spinal adenosine modulates capsaicin-induced depressor reflex: involvement of adenosine A2 receptor.

1. The depressor responses to i.a. and i.v. injection of capsaicin (CAP) were blocked following intrathecal (i.t.) perfusion of [D-Pro2, D-Trp7,9] substance P, a specific substance P antagonist. This confirmed that the CAP-elicited depressor reflex is mediated by substance P-containing afferent fibres. 2. The regulatory roles of spinal adenosine in the CAP-evoked substance P release and the possible involvement of adenosine A2 receptors were analyzed by analyzing the changes in cardiovascular responses to i.a. and i.v. injection of CAP after various pretreatments with adenosine agonists and antagonists, administered subcutaneously or intrathecally.

Adenosine↗

PubMed1993

Effects of histamine on intracellular Na+ activity and twitch tension in guinea pig papillary muscles.

Effects of histamine on the twitch tension, intracellular Na+ activity (aiNa), and action potential were simultaneously and continuously measured in the isolated cardiac papillary muscle of guinea pigs. In the driven fiber at 60 beats/ min, histamine induced a concentration-dependent positive inotropic effect, and apparently increased the amplitude of the action potential and shortened the duration at 3 microM, and significantly decreased aiNa by 6.7% from the control value of 4.5 +/- 0.1 mM (n = 6, p < 0.05) at 0.3 microM. Cimetidine at 10 microM did not produce any significant effect but partially antagonized the action of histamine. The respective concentrations of 1 and 3 microM histamine significantly decreased aiNa by 5.4 and 14.3% from the control 5.6 +/- 0.1 mM (n = 6, p < 0.05) in the presence of 10 microM cimetidine. Chlorpheniramine at 10 microM significantly reduced the twitch tension and aiNa, and prolonged the action potential duration. Histamine at 1 microM increased the twitch tension and decreased aiNa from 4.5 +/- 0.1 to 4.1 +/- 0.1 mM (n = 5, p < 0.05) in the presence of 10 microM chlorpheniramine. The combined application of 10 microM cimetidine and 10 microM chlorpheniramine reduced the twitch tension and abolished most effects of histamine. In high potassium solution (16.2 mM), 1 microM histamine significantly decreased aiNa by 12.9% from the control of 3.1 +/- 0.2 mM (n = 5, p < 0.05). The treatment of 0.5 or 1 microM ouabain increased the tension development and aiNa, and abolished the decrease in aiNa produced by the effect of histamine. The results suggest that histamine can directly stimulate Na-K pump in sarcolemma through means of the activation of both H1- and H2-receptors.

Action Potentials↗

PubMed1993

[Pharmacokinetics of moracizine and moracizine sulfoxide in healthy volunteers].

The pharmacokinetics of moracizine (Mor) and moracizine sulfoxide (Mor-SO) determined by reversed phase HPLC was reported. The data in 6 volunteers after a single oral dose (600 mg) showed an one-compartment open model. The peak concentration in plasma (2.1 +/- 0.4 micrograms.ml-1) of Mor reached within 1-2 h. The Mor-SO concentration in plasma was much lower (0.19 +/- 0.06 micrograms.ml-1) than that of Mor, but its elimination T1/2 (2.3 +/- 1.0 h) was similar to that of Mor (1.5 +/- 1.0 h). The recoveries of Mor, Mor-SO, moracizine sulfone (Mor-SO2) in urine within 48 h were 0.07%, 0.25%, and 0.06% of the total dose, respectively. The Mor and Mor-SO concentration ranges in plasma for 9 arrhythmic patients after 2-wk therapeutic trial were 0.09 +/- 0.07 to 0.9 +/- 0.5 microgram.ml-1 and 0.040 +/- 0.023 to 0.15 +/- 0.06 micrograms.ml-1, respectively. These results suggested that cumulative doses would not result in accumulation of the drug and the anti-arrhythmic effect of Mor-SO might not be realized.

Adult↗

PubMed1993

[Identification of latent HBV infection in primary hepatic carcinoma and liver cirrhosis with polymerase chain reaction].

In order to explore latent. HBV infection in primary hepatic carcinoma (PHC) and liver cirrhosis (LC), serum HBV X and S gene were tested with polymerase chain reaction in 40 cases of PHC and LC with both negative HBsAg and HBeAg. The positive rates for X and S gene were much the same. The S gene-positive cases were, however, slightly more than the X gene-positive ones. In the cases of PHC and LC with all the five serum immunologic markers negative HBV DNA was found in 56.3% (9/16) and 45.5% (5/11) of the cases respectively. Of those patients with positive anti-HBs or anti-HBe, HBV DNA was found in 4/8 and 1/4 of the cases respectively. It was shown that in the cases of PHC and LC with all the five markers-negative, about half of them seems to be still related with HBV infection. Some of the PHC and LC cases with positive anti-HBs or anti-HBe may also have low level of viral replication. Detection of HBV DNA with multiple genes is of help to identify more PHC and LC patients with latent HBV infection.

Carcinoma, Hepatocellular↗

PubMed1993

Epinephrine stimulates Na-K pump by mediation of alpha-and beta-adrenoceptors in canine cardiac Purkinje fibers.

The effects of epinephrine on the twitch tension, intracellular Na+ activity (aiNa), and action potential were simultaneously investigated in an electrically driven canine Purkinje fiber. Epinephrine (0.3 microM) increased the twitch tension, duration of action potential (APD), and plateau height with a fall in aiNa. The twitch force increased during exposure and decreased during recovery. Propranolol (3 microM) or lidocaine (10 microM) decreased the twitch tension, APD, and aiNa when added to the bathing solution alone. They partially inhibited the effects of epinephrine (0.3 microM) on the development of the twitch tension and action potential and on the decrease of aiNa. Phentolamine (2 microM) reduced the twitch tension and plateau height of the action potential but failed to eliminate the action of epinephrine on the fibers. The combined action of phentolamine and epinephrine abbreviated the APD. The effect of epinephrine on the decrease of aiNa was entirely suppressed when the fiber was pretreated with propranolol (1 microM) and phentolamine (1 microM) or in a potassium-depleted solution. The results indicate that epinephrine exerts effects on the canine Purkinje fiber by the mediation of alpha-and beta-adrenoceptors. Adrenoceptor stimulation of both types is involved in the positive inotropic effect and the activation of the sarcolemmal Na-K pump.

Animals↗

PubMed1993

Doppler velocimetry study of maternal hemodynamics and fetal vascular pattern in a case of chronic hypertension with superimposed severe preeclampsia and impending fetal death.

A case is presented of chronic hypertension with superimposed severe preeclampsia; absence of end-diastolic velocity in the umbilical artery had been noted at gestational age of 20 weeks. Because the fetus was previable, the mother was treated with pharmacotherapy according to the maternal hemodynamics; uteroplacental circulation and fetal vascular blood flow were monitored by Doppler velocimetry. Deterioration of the fetal condition occurred during crossover of maternal hemodynamics from a low-resistance to a high-resistance state. Serial Doppler velocimetry studies done within 40 minutes of fetal death are described. There were two types of absent end-diastolic velocity in the umbilical artery, and the pathophysiology and clinical management may be quite a different in these two situations.

Adult↗

PubMed1992

Control of glycoprotein synthesis. Characterization of (1-->4)-N-acetyl-beta-D-glucosaminyltransferases acting on the alpha-D-(1-->3)- and alpha-D-(1-->6)-linked arms of N-linked oligosaccharides.

Hen oviduct membranes contain at least three N-acetyl-beta-D-glucosaminyltransferases (GlcNAc-T) that attach a beta GlcNAc residue in (1-4)-linkage to a D-Man p residue of the N-linked oligosaccharide core, i.e., (1-->4)-beta-D-GlcNAc-T III which adds a "bisecting" GlcNAc group to form the beta-D-GlcpNAc-(1-->4)-beta-D-Man p-(1-->4)-D-GlcNAc moiety; (1-->2)-beta-D-GlcNAc-T IV which adds a GlcNAc group to the (1-->3)-alpha-D-Man arm to form the beta-D-GlcpNAc-(1-->4)-[beta-D- GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->3)-beta-D-Man p-(1-->4)-D-GlcpNAc component; and (1-->4)-beta-D-GlcNAc-T VI which adds a GlcNAc group to the alpha-D-Man p residue of beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R to form beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc-(1-->4)]-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R. We now report a novel (1-->4)-beta-D-GlcNAc-T activity (GlcNAc-T VI') in hen oviduct membranes that transfers GlcNAc to beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->6)- beta-D-Man p-R. The structure of the enzyme product was confirmed by 1H NMR spectroscopy, FAB-mass spectrometry and methylation analysis. Previous work with GlcNAc-T IV was carried out with biantennary substrates; we now show that hen oviduct membrane GlcNAc-T IV can also transfer GlcNAc to monoantennary beta-D-GlcpNAc-(1-->2)-alpha-D-Manp-(1-->3)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p- (1-->3)-beta-D-Man p-R. The findings that GlcNAc-T VI' and IV have similar kinetic characteristics and that hen oviduct membranes can convert methyl beta-D-GlcpNAc-(1-->2)-alpha-D-Man p to methyl beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p suggest that these two activities may be due to the same enzyme. The R-group of the beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p (or Glcp)-R substrate has an important influence on GlcNAc-T VI' enzyme activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

Effects of hemin and porphyrin compounds on intersubunit disulfide formation of heme-regulated eIF-2 alpha kinase and the regulation of protein synthesis in reticulocyte lysates.

To study the mechanism by which heme regulates the heme-regulated eIF-2 alpha kinase (HRI), the effects of various protoporphyrin IX (PP) compounds on the kinase activities and intersubunit disulfide formation of HRI and on protein synthesis in reticulocyte lysates were examined. Hemin and cobalt protoporphyrin (CoPP) are more effective than ZnPP, NiPP, SnPP, and metal-free PP in promoting intersubunit disulfide bond formation in HRI, in inhibiting the autokinase and eIF-2 alpha kinase activities of HRI, in inhibiting phosphorylation of eIF-2 alpha in rabbit reticulocytes, in maintaining protein synthesis, and in reversing the inhibition of protein synthesis in heme deficiency. There is an apparent correlation of in vitro intersubunit disulfide formation of HRI and the regulation of HRI kinase activities and protein synthesis by these porphyrin compounds. HRI in the reticulocyte lysate can be cross-linked by 1,6-bismaleimidohexane (bis-NEM). The formation of bis-NEM cross-linked dimers in lysates is prevented completely by N-ethylmaleimide (NEM) which alkylates free sulfhydryl groups and is diminished by hemin and CoPP. These results support the view that HRI in hemin-supplemented lysates is in equilibrium between the noncovalently linked dimer and the disulfide-linked dimer. The molecular size of HRI in control, hemin-supplemented, or NEM-treated hemin-supplemented lysates is identical to that of purified HRI; activation of HRI and changes in its thiol status do not significantly affect its molecular size.

Animals↗