Biomedical subjects

J M Yang

Publications and source records attributed to J M Yang.

At least 127 records · Page 7Linked to original sources

PubMed1996

Calorimetric characterization of the formation of acrylic type bone cements.

The formation of acrylic bone cements upon heating was investigated by differential scanning calorimetry (DSC). The effects of the contents of initiators, accelerator, biocompatibilizer, and crosslinking agents on the rate and the heat of polymerization during DSC heating were studied. The rate and the heat of polymerization (delta H) were characterized by the peak temperature and the area of the DSC exotherm, respectively. It was found that both the rate and heat of polymerization decreased with increasing heating rate. The delta H was increased considerably with increasing benzoyl peroxide (BPO) initiator concentration from 1 to 10% (w/v), whereas the rate of polymerization was reduced significantly. An increase in azobisisobutyronitrile (AIBN) initiator concentration also induced an increase in delta H, but the rate of reaction was not affected considerably. The addition of accelerator promoted the rate of reaction but resulted in a drop in delta H. The rate of polymerization for the system containing BPO initiator was increased quite significantly with the addition of hydroxyethyl methacrylate (HEMA) biocompatibilizer, while the delta H was slightly increased. For the system using AIBN as the initiator, the rate of polymerization was decreased slightly and the delta H dropped significantly with the addition of HEMA. The effect of ethylene glycol dimethacrylate (EGDMA) crosslinking agent was also examined. Polymerization became more rapid with the addition of EGDMA in the bone cement using BPO initiator, while it remained approximately constant for the system using AIBN as the initiator. No systematic change in delta H was observed with the addition of EGDMA in both systems. This study demonstrated that DSC is a potential tool to measure the amount of heat released and also the rate of polymerization for bone cements.

Acrylates↗

PubMed1996

P-glycoprotein-mediated multidrug resistance: experimental and clinical strategies for its reversal.

The study of the cellular, biochemical, and molecular biology and pharmacology of MDR has provided one of the most active and exciting areas within cancer research and one that holds great promise for translation into clinical benefit. While convincing evidence for the functional role of P-gp in mediating clinical drug resistance in humans remains elusive, studies of the clinical expression of P-gp and trials of chemosensitizers with cancer chemotherapy suggest "resistance modification" strategies may be effective in some tumors with intrinsic or acquired drug resistance. However, even if P-gp-associated MDR proves to be a relevant and reversible cause of clinical drug resistance, numerous problems remain to be solved before effective clinical chemosensitization may be achieved. Such factors as absorption, distribution, and metabolism; the effect of chemosensitizers on chemotherapeutic drug clearance; toxicity to normal tissues expressing P-gp; and the most efficacious modulator regimens all remain to be defined in vivo. Clearly, the identification of more specific, potent, and less clinically toxic chemosensitizers for clinical use remains critical to the possible success of this approach. Nonetheless, the finding that a number of pharmacological agents can antagonize a well-characterized form of experimental drug resistance provides promise for potential clinical applications. Further study of chemosensitizers in humans and the rational design of novel chemosensitizers with improved activity should define the importance of MDR in clinically resistant cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Amplification of 19q13.1-q13.2 sequences in ovarian cancer. G-band, FISH, and molecular studies.

In this study of ovarian carcinoma, we extended previous findings by performing FISH using chromosome 19 paint and microFISH probes and patient samples with and without abnormalities of chromosome 19 identified by G-banding. Karyotype interpretations of der(19) were confirmed, while additional 19 translocations were also detected by FISH with 19WCP in some cases. Similar FISH studies of ovarian carcinoma cell lines found chromosome 19 abnormalities even after extensive in vitro culture. MicroFISH probes were generated by chromosome microdissection from two cases with hsr(19) and mapped to 19q13.2 and 19q13.1-.2, respectively. FISH with these microFISH probes alone or in combination with a 19WCP probe to four patient samples and seven cell lines showed that 65% of chromosome 19 structural abnormalities contained 19q13.1-q13.2 sequences, sometimes as large hsrs. Ovarian cancer cell lines showed amplification and overexpression of the AKT2 putative oncogene, but not the ERCC-2 DNA repair gene in this chromosomal region. In addition to AKT2, amplification and overexpression of other yet-unidentified genes in the 19q13.1-q13.2 region may contribute to ovarian carcinoma pathogenesis or progression.

Chromosome Aberrations↗

PubMed1996

Sodium nonivamide acetate: a non-pungently antinociceptive capsaicin derivative with unusual anti-inflammatory properties.

1. Bradykinin-induced vascular pain in conscious rats, hyperalgesia in the rat hind paw, rat hind paw edema induced by compound 48/80 and carrageenin and dye exudation induced by intraperitoneal injection of 0.7% acetic acid in mice were all inhibited by sodium nonivamide acetate (SNA). 2. Collagen and arachidonic acid-induced rabbit platelet aggregations were inhibited by SNA and capsaicin. In human platelet microsomes, prostaglandin E2 formation in arachidonic acid metabolite was not inhibited by SNA but was inhibited by capsaicin and indomethacin; thromboxane B2 formation and its synthetase activity were inhibited by SNA and capsaicin. 3. In the extracellular recording, SNA could not decrease the action potential amplitude of the vagus nerve. 4. The motor activity of mice induced by caffeine (1.0 mg/kg) was inhibited by SNA and capsaicin.

Animals↗

PubMed1996

Proliferation tissue polypeptide antigen distinguishes malignant mucinous cystadenocarcinomas from benign cystic tumors and pseudocysts.

BACKGROUND: Cystic lesions of the pancreas include inflammatory pseudocysts, serous cystadenomas, and mucinous cystic tumors, some of which are malignant. Previous studies have shown that malignant mucinous tumors differ from benign pancreatic cysts in proliferative activity, secretion of tumor markers, and expression of growth factor receptors. Analysis of aspirated cyst fluid for tumor markers, viscosity, and cytologic examination has been proposed as an aid to preoperative differential diagnosis. Tissue polypeptide antigen (TPA) is a soluble proliferation antigen produced by rapidly dividing tissues, including conventional ductal pancreatic carcinoma. TPA levels in pancreatic cyst fluids have not been reported. METHODS: Tissue polypeptide antigen levels were determined in 46 pancreatic cyst fluids using a commercial immunoassay technique. RESULTS: Mucinous cystadenocarcinomas exhibited significantly higher levels of cyst fluid TPA than benign cystic lesions, including pseudocysts, serous cystadenomas, and benign mucinous cystadenomas (mean 910,672 U/mL, median 300,900 U/mL, range 16,600 to 4,210,000 U/mL for malignant mucinous cystadenocarcinomas; versus mean 16,082 U/mL, median 2,455 U/mL, range 0 to 155,000 U/mL for benign cystic lesions considered as a group; P < 0.0002). In 75% of the malignant cysts, the TPA values were in excess of 100,000 U/mL. Pseudocysts exhibited the lowest TPA levels (mean 2,108 U/mL, median 604 U/mL, range 0 to 20,240 U/mL) and were significantly lower than the values observed in cystic tumors (P < 0.0005). Serous and benign mucinous tumors had intermediate levels of TPA. CONCLUSIONS: Elevated levels of the proliferation antigen TPA in malignant pancreatic cysts correlate with earlier observations of increased proliferative activity and overexpression of growth factor receptors in these tumors. The TPA measurement may be a useful addition to previously reported cyst fluid markers to aid in preoperative differential diagnosis. Markedly elevated or very low values indicate a malignant or benign cyst, respectively.

Antigens, Neoplasm↗

PubMed1996

Interactions between inositol trisphosphate and Ca2+ dependent Ca2+ release mechanisms on the endoplasmic reticulum of permeabilised bovine aortic endothelial cells.

In this paper we describe data from cultured bovine aortic endothelial (BAE) cells demonstrating a Ca2+ induced Ca2+ release (CICR) process which appears to have pharmacological properties different from CICR mechanisms in other cell types. CICR was measured in saponin permeabilised cells in which the internal stores had been preloaded with 45Ca2+. Step increases in the free Ca2+ concentration of the bathing solution, from 10 nM up to 10 microM were found to increase 45Ca2+ loss. This process was completely inhibited by ruthenium red. Caffeine induced a small release of 45Ca2+ and the response to a subsequent stimulation with a Ca2+ step was reduced. In intact cells, ryanodine activated small oscillations in intracellular Ca2+ in the presence, but not the absence, of external Ca2+. However, in permeabilised cells, ryanodine had no effect on either basal efflux or the increased efflux of 45Ca2+ seen following a step increase in free Ca2+. These data suggest the operation of a ruthenium red sensitive but ryanodine insensitive CICR mechanism on the endoplasmic reticulum (ER) which may also be modulated by caffeine. An IP3 dependent 45Ca2+ release was also observed. In the presence of ruthenium red, the IP3 induced 45Ca2+ release was reduced suggesting that CICR may operate to amplify the magnitude of the IP3 response. The Ca2+ dependence of the IP3 induced release was also measured. Co-operativity between IP3 and Ca2+ could not be detected between 100-300 nM Ca2+. The results suggest that the regulation of IP3 induced Ca2+ release may be different in BAE cells, and point to the operation of a 'novel' CICR process and to complex interactions between Ca2+ release systems in BAE cells.

Animals↗

PubMed1996

Identification of metabolites of azaperone in horse urine.

Two metabolites of the tranquilizer azaperone were extracted from alkalinized horse urine after treatment with beta-glucuronidase/sulfatase from limpets (Patella vulgata). The metabolites were identified by a combination of independent chemical synthesis and GC/MS and 1H NMR analysis. The metabolites were identified as 1-(fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)-1-piperazinyl]-1-butanol, designated as 5'-hydroxy-azaperol, and 1-(fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)-1-piperazinyl]-1-butanone, designated as 5'-hydroxyazaperone. A TLC screening test was developed for detecting both metabolites in basic extracts of horse urine treated with beta-glucuronidase/sulfatase. The screening test was used to detect azaperone metabolites in extracts of horse urine collected for 24 h after intravenous administration of azaperone. The administration of azaperone to horses was confirmed by GC/MS identification of 5'-hydroxyazaperone and 5'-hydroxyazaperol from basic extracts of horse urine treated with beta-glucuronidase/sulfatase. The extracted metabolites were treated with bis(trimethylsilyl)acetamide to produce trimethylsilyl (TMS) ether derivatives, and mass spectra and retention times were compared to those of the synthesized metabolites treated in the same manner.

Animals↗

PubMed1996

Expression of the zinc finger gene EVI-1 in ovarian and other cancers.

The EVI-1 gene was originally detected as an ectopic viral insertion site and encodes a nuclear zinc finger DNA-binding protein. Previous studies showed restricted EVI-1 RNA or protein expression during ontogeny; in a kidney and an endometrial carcinoma cell line; and in normal murine oocytes and kidney cells. EVI-1 expression was also detected in a subset of acute myeloid leukaemias (AMLs) and myelodysplasia. Because EVI-1 is expressed in the urogenital tract during development, we examined ovarian cancers and normal ovaries for EVI-1 RNA expression using reverse transcription polymerase chain reaction (RT-PCR) and RNAase protection. Chromosome abnormalities were examined using karyotypes and whole chromosome 3 and 3q26 fluorescence in situ hybridisation (FISH). RNA from six primary ovarian tumours, five normal ovaries and 47 tumour cell lines (25 ovarian, seven melanoma, three prostate, seven breast and one each of bladder, endometrial, lung, epidermoid and histiocytic lymphoma) was studied. Five of six primary ovarian tumours, three of five normal ovaries and 22 of 25 ovarian cell lines expressed EVI-1 RNA. A variety of other non-haematological cancers also expressed EVI-1 RNA. Immunostaining of ovarian cancer cell lines revealed nuclear EVI-1 protein. In contrast, normal ovary stained primarily within oocytes and faintly in stroma. Primary ovarian tumours showed nuclear and intense, diffuse cytoplasmic staining. Quantitation of EVI-1 RNA, performed using RNAase protection, showed ovarian carcinoma cells expressed 0 to 40 times the EVI-1 RNA in normal ovary, and 0-6 times the levels in leukaemia cell lines. Southern analyses of ovarian carcinoma cell lines showed no amplification or rearrangements involving EVI-1. In some acute leukaemias, activation of EVI-1 transcription is associated with translocations involving 3q26, the site of the EVI-1 gene. Ovarian carcinoma karyotypes showed one line with quadruplication 3(q24q27), but no other clonal structural rearrangements involving 3q26. However, whole chromsome 3 and 3q26 FISH performed on lines with high EVI-1 expression showed translocations involving chromosome 3q26. EVI-1 is overexpressed in ovarian cancer compared with normal ovaries, suggesting a role for EVI-1 in solid tumour carcinogenesis or progression. Mechanisms underlying EVI-1 overexpression remain unclear, but may include rearrangements involving chromosome 3q26.

Blotting, Southern↗

PubMed1996

Isolation of presumptive Streptobacillus moniliformis from abscesses associated with the female genital tract.

We report three cases in which Streptobacillus moniliformis was isolated from abscesses. Abscess material in each case contained small, pleomorphic, gram-negative to gram-variable bacilli. Anaerobic blood agar cultures yielded pinpoint colonies adjacent to small gray-white colonies. The pinpoint colonies did not gram stain, and the gray-white colonies varied from gram-variable coccobacilli to long, curly, gram-variable rods. The pinpoint colonies microscopically resembled L-forms on Dienes-stained agar preparation. Subculture to serum-supplemented thioglycolate broth demonstrated "puff ball" colonies. Fatty acid profiles obtained with use of gas chromatography coupled with mass spectrometry showed major peaks for C16:0, C18:2, C18:1, and C18:0 fatty acids, a profile characteristic of S. moniliformis. Results of biochemical testing of each isolate were equivocal. S. moniliformis, bacterial L-forms, and common isolates from genital tract abscesses are discussed.

Abscess↗

PubMed1996

A novel H1 mutation in the keratin 1 chain in epidermolytic hyperkeratosis.

We report a novel mutation in a case of epidermolytic hyperkeratosis that results in a proline for arginine substitution in the penultimate residue position of the H1 subdomain of the keratin 1 chain, which is near the beginning of the rod domain. This causes a severe clinical disease classified as PS-2. Therefore, the H1 subdomain is probably equally important for the maintenance of keratin intermediate filament integrity as the rod domain. Since earlier concepts had implied that mutations in the H1 subdomain produce milder disease, this case suggests that attempts to correlate mutations with disease presentation remain problematic.

Amino Acid Sequence↗

PubMed1996

Size of 22q deletions in four previously reported patients with conotruncal anomaly face syndrome.

Conotruncal anomaly face syndrome (CTAFS) was distinguished from velo-cardio-facial syndrome (VCFS) in a bind study, yet shared the finding of 22q11.2 deletions. This work has been extended to show that the 22q11.2 deletions in CTAFS greatly overlap those found in VCFS and many DiGeorge patients. The reason for dissimilar phenotypes with apparently similar 22q11.2 deletions is not yet known.

Abnormalities, Multiple↗

PubMed1996

Regional mapping of the human platelet-activating factor receptor gene (PTAFR) to 1p35-->p34.3 by fluorescence in situ hybridization.

The human platelet-activating factor cell-surface receptor (PTAFR) is a G protein-coupled receptor thought to contribute to many atopic and inflammatory diseases and, perhaps, to the growth of some neoplasms. Exploring the possibility that the PTAFR might be involved in the genetic predisposition to any disease requires knowledge of its chromosomal localization. In this paper we have used a 20-kb human genomic fragment containing the coding sequence of the cloned PTAFR to determine the regional chromosomal localization of the gene. Using fluorescence in situ hybridization, the localization of the human PTAFR gene was mapped to 1p35-->p34.3.

Chromosome Mapping↗

PubMed1996

Effects of phenylephrine on intracellular Na+ and H+ activities in guinea-pig cardiac ventricular papillary muscles.

Effects of phenylephrine (PE) on the contractility, intracellular Na+ activity (aNai), intracellular H+ activity (pHi), and membrane potential in guinea-pig cardiac ventricular papillary muscles were studied. In beating fibers, PE significantly increased the twitch offsion, pHi and the action potential duration but decreased aNai. These effects could be inhibited by phentolamine, but not by propranolol. In quiescent fibers, PE also increased the resting tension and pHi, and decreased aNai. Pretreatment with phentolamine completely abolished the effect of PE. Methylisobutyl amiloride (MIA), a potent inhibitor of Na(+)-H+ exchanger, significantly decreased membrane potential, aNai, and pHi without changing the resting tension. PE in the presence of MIA increased the resting tension and further decreased aNai without significant changes in membrane potential and pHi. Ouabain significantly decreased membrane potential and pHi, and increased the resting tension and aNai. In the ouabain-treated fiber, PE further increased the resting tension without decreasing aNai or increasing pHi. From these results, it appears that PE activates the Na(+)-K+ pump and Na(+)-H+ exchange through alpha-adrenoceptors. Activation of the Na(+)-K+ pump contributes, at least in part, to the enhanced Na(+)-H+ exchange. The increase in contractile force associated with a decrease in aNai is suggested to result from the intracellular alkalization and increased sensitivity of contractile protein to Ca2+.

Animals↗

PubMed1996

Simultaneous effects of carbachol on intracellular Na+ activity, action potential, and twitch tension in guinea-pig cardiac ventricular papillary muscles.

Effects of carbachol (CCh) on the twitch tension, intracellular Na+ activity (aNai), and action potential were simultaneously measured in guinea-pig cardiac ventricular papillary muscles. In fibers driven at 60 beats/min, 100 microM CCh significantly increased the twitch tension and aNai, and decreased the action potential duration at 30 and 90% repolarization (APD30 and APD90) without changing the maximum rate of the rise of the upstroke (Vmax). Staurosporine (1 microM) alone gradually decreased the twitch tension and aNai without changing the action potential. In the presence of staurosporine, the administration of CCh restored aNai and caused the same changes in twitch tension and APD shortening with no effect on Vmax. Pretreatment with 1 microM atropine completely eliminated the effects of 100 microM CCh. Cesium (20 mM) depolarized the cell membrane and significantly increased the twitch tension and APD90 with decreases in the Vmax and aNai. CCh (100 microM) in the presence of 20 mM Cs+ biphasically decreased and increased the twitch tension and significantly decreased the Vmax and aNai with an increase in the APD90. The results suggest that the muscarinic receptor-mediated increase of aNai is protein kinase C-independent. The aNai increase is associated with the positive inotropic effect and the abbreviation of the action potential duration. In addition to the increase in aNai, the increase of the myofibrillar calcium sensitivity involved is responsible for the positive inotropic effect which is still evident after the sodium influx is inhibited by Cs+.

Action Potentials↗

PubMed1996

Central and peripheral hemodynamics in severe preeclampsia.

BACKGROUND: Doppler velocimetry, a new tool for measuring blood flow, vascular resistance, and central hemodynamics can be applied to monitor those patients at risk and provide therapeutic concepts for preeclampsia. This study was designed to use a Doppler velocimetry study to correlate the relationship between central hemodynamics, uteroplacental circulation, and the perinatal outcome in severe preeclampsia. METHODS: Thirty-one patients with severe preeclampsia, not superimposed with any medical disorder and not on antihypertensive treatment prior to admission, were enrolled in this study. On admission, laboratory determination of the maternal blood chemistry and hematogram, together with a Doppler ultrasound study of the maternal hemodynamics, and umbilical and uterine arteries, were performed. Antihypertensive agents including hydralazine, atenolol, and labetolol were given according to the state of the maternal central hemodynamics. Data were collected on the general status of the patients, the results of the Doppler ultrasound study, and the perinatal outcome. RESULTS: Patients were divided into three groups based on the systemic vascular resistance. The left ventricular function and cardiac index declined with increase in vascular resistance. The high-resistance group had a significantly high incidence of infants small for gestational age. Poor fetal growth in the high-resistance group could be attributed to the summation of underperfusion due to decreased uteroplacental blood flow and was frequently associated with maternal hemoconcentration. CONCLUSIONS: Although global vasospasm has been considered to be the basic pathophysiology of preeclampsia, the central hemodynamics varies between, and even in the same, patients. Regional vasospasm in the uteroplacental circulation occurs earlier than in the systemic circulation as a whole. A high cardiac-output in low systemic-vascular-resistance might compensate in those pregnancies with high uterine artery resistance to maintain adequate uteroplacental perfusion.

Adult↗

PubMed1996

A case of combined gastrojejunal and gastrocolic fistula secondary to gastric cancer.

A rare case of gastric cancer associated with gastrojejunal and gastrocolic fistula is presented. A 56-year-old man who had been diagnosed with advanced gastric cancer(Borrmann's type III) 5 months previously was admitted due to watery diarrhea and frequent vomiting for 2 weeks. Fluoroscopic examination was visualized two abnormal passage of contrast medium from the stomach, one to the colon, and the other to the jejunum. Gastrofiberscopy revealed that the tumor on the great curvature of the body appeared to penetrate into the colon, while the other one on the antrum directly invaded into the jejunum. The patient was treated conservatively with total parenteral nutrition and pain control.

Colonic Diseases↗

PubMed1996

The distribution of HgCl2 in rat body and its effects on fetus.

Both female and male Wistar rats were dividend into 3 groups according to their body weights. The two test groups were given 75 micrograms/ml and 7.5 micrograms/ml HgCl, respectively, via drinking water, while the control group was given distilled water. Animals were mated after the male rats were treated for 12 weeks and female rats for 2 weeks. Blood samples from rats were taken on the 18th day of the pregnancy and the results showed that the HgCl2 was absorbed and stored in the blood in the form of inorganic mercury. The greatest amount of HgCl2 was found in the kidney. The placenta and the tests also had high mercury deposits. Fetuses showed low levels of HgCl2, thus, the placenta appears to serve as a barrier against HgCl2. No pathological changes were observed in the placenta, ovary, liver, and kidney in the female rats, but the epithelial cells of the rental proximal convoluted tubules were cloudy and swelling. The renal corpuscle showed no changes in the male rats. Pathological examination showed that a portion of the seminiferous epithelia were falling off, and the number of sperm released by the male was reduced. Examination by electron microscopy revealed that particulate fat was increased in sperm cells, which suggests that spermatozoa had been degenerated and were possibly one of the causes for the decreased rates of pregnancy in the exposed groups. No malformation of organs and bones in the rat fetuses were observed.

Animals↗

PubMed1996

Effects of severe preeclampsia with different doppler velocimetries on extra- and intrauterine environments.

We evaluated the perinatal outcome of fetuses and maternal condition of 47 patients with severe preeclampsia. Antepartum fetal surveillance (within 2 days of delivery or fetal death) included the nonstress test, Doppler velocimetry of the umbilical and uterine arteries, amniotic fluid assessment, maternal blood chemistry and hemogram. Pregnancies with abnormal Doppler velocimetry in the umbilical and uterine arteries had poor perinatal outcomes as judged by the incidence of abnormal antepartum fetal surveillance, acute fetal distress mandating immediate delivery, small for gestational age infants, perinatal morbidity and mortality and prematurity. These fetuses were at a high risk of acute and chronic hypoxia. Maternal blood chemistries and hemograms revealed a high incidence of hepatocellular dysfunction, renal insufficiency, hemoconcentration and thrombocytopenia. In cases of severe preeclampsia, those with abnormal Doppler velocimetry of both umbilical and uterine arteries, had poor extra- and intrauterine environments. Therefore, aggressive rather than expectant management was more suitable. For those with normal umbilical artery resistance and either normal or abnormal uterine artery resistance, careful management with close monitoring of both maternal and fetal status was possible in patients who were far from term.

Adult↗