PubMed Health⌕ Search

Biomedical subjects

Y L Chang

Publications and source records attributed to Y L Chang.

At least 109 records · Page 6Linked to original sources
PubMed1996

Acute pancreatitis masquerading as testicular torsion.

A 40-year-old man presented with fat necrosis of scrotum as the complication of acute pancreatitis. Excessive fluid accumulation in the pancreas and the extrapancreatic spaces, including around the spermatic cord, was seen on computed tomography. Surgical specimen showed typical fat necrosis of tunica vaginalis and the spermatic cord. After the surgery, pain of the testicle subsided completely, without recurrence. From the clinical presentation alone, it had been difficult to differentiate this patient's condition from torsion of the spermatic cord.

Acute Disease↗
PubMed1996

Nucleolar organizer regions as a prognostic factor in surgically treated lung cancer patients.

The prognostic value of the number of nucleolar organizer regions (NORs) (DNA loops in the nucleus) in tumor cells from various kinds of malignancies has been widely studied in recent years. During the period 1989 to 1992, a total of 73 primary lung tumors was examined for the number of NORs by silver staining AgNOR proteins on the stump smear of resected specimens in this hospital. The relations of the mean number of AgNOR per cell with other factors such as sex, age, habit of smoking, performance status, tumor location, tumor size, pathological stage, histological type, degree of differentiation, and whether histologically vascular or lymphatic invasion were analysed. It was found that the mean number of AgNOR was significantly different between positives and negatives of histologically vascular or lymphatic invasion (6.4 +/- 0.4 vs 5.5 +/- 0.2) (p < 0.05). Both single and multiple-variate analysis of patient survival revealed that the mean number of AgNOR was a significant prognostic factor, as were pathological stage, histological type, and performance status of the patient. Patients with a higher mean number of AgNOR (> 7) had a significantly worse prognosis compared with those with less AgNOR (< or = 7) (median survival 28 versus 43 months) (p < 0.05). It was concluded that the mean number of AgNOR of tumor cells is a significant prognostic factor in surgically treated lung cancer patients.

Adult↗
PubMed1996

(+/-)-Govadine and (+/-)-THP, two tetrahydroprotoberberine alkaloids, as selective alpha 1-adrenoceptor antagonists in vascular smooth muscle cells.

(+/-)-Govadine and (+/-)-THP ((+/-)-2,3,10,11-tetrahydroxytetrahydroprotoberberine HBr) have been shown to inhibit noradrenaline-induced contraction of rat thoracic aortae. The pharmacological activity of the compounds was determined in thoracic aortae and cardiac tissue isolated from the rat and in trachea isolated from the guinea-pig to determine the selectivity of the compounds towards different types of receptor. (+/-)-Govadine and (+/-)-THP were found to be alpha 1-adrenoceptor blocking agents in rat thoracic aorta as revealed by their competitive antagonism of vasoconstriction induced by noradrenaline (pA2 = 6.57 +/- 0.07 and 5.93 +/- 0.06, respectively) or phenylephrine (pA2 = 6.74 +/- 0.08 and 6.06 +/- 0.10, respectively). Removal of endothelium did not affect the antagonistic potencies of (+/-)-govadine (pA2 = 6.83 +/- 0.09) and (+/-)-THP (pA2 = 6.25 +/- 0.06) on phenylephrine-induced vasoconstriction. They were more potent than yohimbine (pA2 = 6.05 +/- 0.05), but less so than phentolamine (pA2 = 7.54 +/- 0.11) and prazosin (pA2 = 9.27 +/- 0.12). (+/-)-Govadine and (+/-)-THP, furthermore, inhibited [3H]inositol monophosphate formation caused by noradrenaline (3 microM) in rat thoracic aorta. (+/-)-Govadine and (+/-)-THP were also alpha 2-adrenoceptor blocking agents with pA2 values 5.50 +/- 0.13 and 5.41 +/- 0.11, respectively. A high concentration of (+/-)-govadine (30 microM) or (+/-)-THP (30 microM) did not, however, affect the contraction induced by the thromboxane receptor agonist U46619, prostaglandin F2 alpha (PGF2 alpha), 5-hydroxytryptamine (5-HT), angiotensin II, endothelin or high K+ in rat aorta denuded of endothelium. Neither the cyclic AMP nor cyclic GMP content of rat thoracic aorta was, furthermore, changed by (+/-)-govadine or (+/-)-THP. Contraction of guinea-pig trachea caused by carbachol, histamine, leukotriene C4 or neurokinin A was not affected by (+/-)-govadine or (+/-)-THP. (+/-)-Govadine or (+/-)-THP also did not block beta 1- or beta 2-adrenoceptor-mediated responses induced by isoprenaline in rat right atria and guinea-pig trachea. It is concluded that (+/-)-govadine and (+/-)-THP are selective alpha 1-adrenoceptor antagonists in vascular smooth muscle.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1996

Ketorolac versus meperidine for pain relief after orthopaedic surgery.

In this double-blind, randomized, multicenter study, 244 patients with at least moderate pain after major orthopaedic surgery received intramuscular Ketorolac (60 mg followed by 30 mg) or intramuscular meperidine (100 mg or placebo) every 2 to 6 hours as needed for as many as 5 days. Analgesic response was evaluated for 6 hours after initial study drug administration and thereafter each night at bedtime. Both active treatment groups had similar 3-hour summed pain intensity difference and 3-hour total pain relief scores after the first dose that were superior to placebo. The 6-hour summed pain intensity difference and total pain relief scores were significantly higher with Ketorolac than with meperidine or placebo. The mean daily categorical pain intensity scores were comparable with Ketorolac and meperidine, and both were significantly superior to placebo. Patient ratings of overall medication efficacy were significantly better with Ketorolac than with meperidine. In both patient and observer evaluations, Ketorolac was significantly better tolerated than meperidine, and the number of patients reporting adverse events was lower with Ketorolac than with meperidine. Following major orthopaedic surgery, Ketorolac provided effective analgesia that was superior to placebo and at least comparable with meperidine. Ketorolac was better tolerated than meperidine.

Adolescent↗
PubMed1995

The weediness of wild plants: molecular analysis of genes influencing dispersal and persistence of johnsongrass, Sorghum halepense (L.) Pers.

Many major weeds rely upon vegetative dispersal by rhizomes and seed dispersal by "shattering" of the mature inflorescence. We report molecular analysis of these traits in a cross between cultivated and wild species of Sorghum that are the probable progenitors of the major weed "johnsongrass." By restriction fragment length polymorphism mapping, variation in the number of rhizomes producing above-ground shoots was associated with three quantitative trait loci (QTLs). Variation in regrowth (ratooning) after overwintering was associated with QTLs accounting for additional rhizomatous growth and with QTLs influencing tillering. Vegetative buds that become rhizomes are similar to those that become tillers--one QTL appears to influence the number of such vegetative buds available, and additional independent genes determine whether individual buds differentiate into tillers or rhizomes. DNA markers described herein facilitate cloning of genes associated with weediness, comparative study of rhizomatousness in other Poaceae, and assessment of gene flow between cultivated and weedy sorghums--a risk that constrains improvement of sorghum through biotechnology. Cloning of "weediness" genes may create opportunities for plant growth regulation, in suppressing propagation of weeds and enhancing productivity of major forage, turf, and "ratoon" crops.

Journal Article↗
PubMed1995

New p-quinonoid aporphine alkaloids and antiplatelet aggregation constituents of Hernandia sonora.

Three minor new p-quinonoid aporphine alkaloids, sonodione (1), demethylsonodione (2), and norsonodione (3), have been additionally isolated from the stem bark of Hernandia sonora. The structures of these compounds were elucidated by spectral analysis. Among the isolates obtained till now, five compounds, ovigerine (4), hernangerine (5), N-methylhernangerine (6), (+)-malekulatine (7), and isovanillin (8) showed moderate antiplatelet aggregation activity in vitro.

Animals↗
PubMed1995

Functional reconstruction of trans regulation of the Ultrabithorax promoter by the products of two antagonistic genes, trithorax and Polycomb.

Maintenance of the "on-off" state of Drosophila homeotic genes in Antennapedia and bithorax complexes requires activities of the trithorax and Polycomb groups of genes. To identify cis-acting sequences for functional reconstruction of regulation by both trithorax and Polycomb, we examined the expression patterns of several Ubx-lacZ transgenes that carry upstream fragments corresponding to a region of approximately 50 kb. A 14.5-kb fragment from the postbithorax/bithoraxoid region of Ultrabithorax exhibited proper regulation by both trithorax and Polycomb in the embryonic central nervous system. Using a Drosophila haploid cell line for transient expression, we found that trithorax or Polycomb can function independently through this upstream fragment to activate or repress the Ultrabithorax promoter, respectively. Studies of deletion mutants of trithorax and Polycomb demonstrated that trithorax-dependent activation requires the central zinc-binding domain, while Polycomb-dependent repression requires the intact chromodomain. In addition, trithorax-dependent activity can be abrogated by increasing the amount of Polycomb, suggesting a competitive interaction between the products of trithorax and Polycomb. Deletion analysis of this fragment demonstrated that a 440-bp fragment contains response elements for both trithorax and Polycomb. Furthermore, we showed that the integrity of the proximal promoter region is essential for trithorax-dependent activation, implicating a long-range interaction for promoter activation.

Animals↗
PubMed1995

Soluble interleukin-2 receptor as a clinical parameter for nasopharyngeal carcinoma.

We evaluated whether the serum soluble interleukin-2 receptor (sIL-2R) may be a parameter to monitor the efficacy of treatment for nasopharyngeal carcinoma (NPC). There were 177 NPC patients and 24 healthy controls. The level of sIL-2R was measured with a sandwich ELISA kit. Higher levels of sIL-2R than for controls were found in NPC patients before treatment and in patients with distant metastasis (p < 0.001). There was, however, no difference in sIL-2R levels between controls and NPC patients after radiotherapy in relapse-free or in primary relapse. The sIL-2R levels in sequential testing revealed good correlation with clinical response. The sIL-2R levels were found to be elevated when distant metastasis was detected. Two patients had elevated sIL-2R level up to 5 months before clinical detection of metastasis. These results indicate that serial measurements of sIL-2R levels are worthwhile for NPC patients in their clinical course. The sIL-2R level proved to be an adjunct clinical parameter to monitor the efficacy of treatment of NPC.

Adult↗
PubMed1994

The primary structure of rat ribosomal protein L15.

The amino acid sequence of the rat 60S ribosomal subunit protein L15 was deduced from the sequence of nucleotides in two recombinant cDNAs. Ribosomal protein L15 has 203 amino acids, the NH2-terminal methionine is removed after translation of the mRNA, and has a molecular weight of 24,000. Hybridization of the cDNA to digests of nuclear DNA suggests that there are 13 to 15 copies of the L15 gene. The mRNA for the protein is about 850 nucleotides in length. Rat L15 is related to ribosomal proteins from other eukaryotes. Rat L15 has the hexapeptide, TYKFFE, that also occurs in the amyloidogenic glycoprotein A4 which is associated with Alzheimer's disease and Down's Syndrome.

Amino Acid Sequence↗
PubMed1994

Intracellular calcium and myosin light chain phosphorylation during U46619-activated vascular contraction.

We investigated the relationship between [Ca2+]i, myosin light chain (LC20) phosphorylation and isometric force in guinea pig aortic strips during contractions activated by a thromboxane A2 analogue, (15S)-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5Z, 13E-dienoic acid (U46619). Isometric force and [Ca2+]i were measured simultaneously using preloaded aequorin as the intracellular calcium indicator. LC20 phosphorylation levels were determined by two dimensional polyacrylamide gel electrophoresis in parallel preparations. Contractions induced by U46619 were accompanied by increases in [Ca2+]i and LC20 phosphorylation. The chelation of extracellular calcium with 2.5 mM EGTA significantly inhibited U46619-induced increases in [Ca2+]i, isometric force and LC20 phosphorylation. Steady-state force assumed a similar dependence on LC20 phosphorylation for contractions stimulated by potassium depolarization, alpha 1-adrenergic agonist phenylephrine and U46619 either in the presence or absence of extracellular calcium. On the contrary, the [Ca2+]i/force relation revealed that both U46619 and phenylephrine stimulated greater isometric force at lower [Ca2+]i than did KCl depolarization. The addition of a protein kinase C inhibitor, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), decreases force without significantly affecting either [Ca2+]i or LC20 phosphorylation levels. These results suggest that in guinea pig aortic smooth muscle U46619 increases the calcium sensitivity of the contractile apparatus but does not change the LC20 phosphorylation/force relation in comparison to K+ depolarization. Protein kinase C is activated during U46619-stimulated contraction and might be involved in mechanisms other than LC20 phosphorylation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Epstein-Barr virus harboring in the parotid gland without tumor association.

The purpose of this study is to clarify the relationship between Epstein-Barr virus (EBV) and tumors of the major salivary gland. EBV DNA was detected by polymerase chain reaction (PCR) in parotid secretions in 56% of patients (n = 32) regardless of the presence of tumors in the parotid gland and in tumor tissues in 19% of surgical specimens (n = 21). By Southern blot-hybridization analysis, we found type A EBV in three patients and type B EBV in one patient. In situ hybridization for EBV genome was positive in surgical specimens of salivary glands in 33% of patients (n = 21). Our results suggest that this virus may not play a role in the pathogenesis of most tumors of the major salivary gland. However, two patients with lymphoepithelial carcinoma were found to have a close relationship to EBV as shown by high titers of antibodies in the sera against EBV related antigens by standard immunofluorescent technique and by the presence of many copies of EBV genome in tumor cells using in situ hybridization.

Adult↗
PubMed1993

The conformation of the sarcin/ricin loop from 28S ribosomal RNA.

The sarcin/ricin loop is a highly conserved sequence found in the RNA of all large ribosomal subunits. The cytotoxins alpha-sarcin and ricin both inactivate ribosomes by cleaving a single bond in that loop. Once it has been attacked, ribosomes no longer interact with elongation factors properly, and translation stops. We have determined the conformation of the sarcin/ricin loop by multinuclear NMR spectroscopy using E73, a 29-nucleotide RNA that has the sarcin/ricin loop sequence and that is sensitive to both toxins in vitro. The sarcin/ricin loop has a compact structure that contains several purine.purine base pairs, a GAGA tetraloop, and a bulged guanosine adjacent to a reverse Hoogsteen A.U pair. It is stabilized by an unusual set of cross-strand base-stacking interactions and imino proton to phosphate oxygen hydrogen bonds. In addition to having interesting structural features, this model explains many of the biochemical observations made about the loop's structure and its reactivity with cytotoxins, and it sheds light on the loop's interactions with elongation factors.

Animals↗
PubMed1993

Daphnoretin, a new protein kinase C activator isolated from Wikstroemia indica C.A. Mey.

Daphnoretin, a biologically active principle isolated from Wikstroemia indica C.A. Mey., caused platelet aggregation in washed rabbit platelets, platelet-rich plasma and whole blood. The aggregation of and ATP release from platelets induced by daphnoretin were similar to phorbol ester- and diacylglycerol-induced aggregation and release. The EC50 values of daphnoretin-, phorbol 12,13-dibutyrate (PDBu)- and 1-oleoyl-2-acetylglycerol (OAG)-induced platelet aggregation in washed rabbit platelets were 17.2 +/- 2.8 microM, 20.6 +/- 2.1 nM and 38.6 +/- 1.7 microM respectively. Platelet aggregation induced by daphnoretin and PDBu was not inhibited by indomethacin, BN52021 or sodium nitroprusside. ADP-scavenging systems, apyrase and phosphocreatine/creatine kinase, showed weak inhibition of the aggregation, and EGTA, triflavin, verapamil and prostaglandin E1 markedly inhibited the aggregation. Staurosporine, a potent protein kinase C inhibitor, suppressed daphnoretin-, PDBu- and OAG-induced aggregation and ATP release in a concentration-dependent manner. The IC50 values of staurosporine on daphnoretin (50 microM)-, PDBu (100 nM)- and OAG (50 microM)-induced aggregation were 37.7 +/- 8.3, 52.2 +/- 6.3 and 42.8 +/- 8.9 nM respectively. Daphnoretin did not cause significant thromboxane B2 formation in rabbit platelets. Neither daphnoretin nor PDBu caused [3H]inositol monophosphate formation or an increase in intracellular Ca2+ concentration in myo-[3H]inositol-labelled and Fura-2-loaded platelets. Platelet cytosolic protein kinase C was activated by daphnoretin and PDBu in a concentration-dependent manner with an EC50 of 12.4 +/- 1.2 microM and 18.7 +/- 1.4 nM respectively. Membrane-associated protein kinase C activity was increased by either daphnoretin or PDBu. [3H]PDBu binding to washed rabbit platelets was inhibited by daphnoretin in a concentration-dependent manner with an IC50 value of 45.2 +/- 5.2 microM. These results indicate that daphnoretin is a protein kinase C activator in rabbit platelets.

Animals↗
PubMed1993

CIS-19, a novel platelet activating factor receptor antagonist: in vitro and in vivo studies.

The effects of CIS-19 (cis-2-(3,4-dimethoxyphenyl)-6-isopropoxy-7-methoxyl-1-(N-methylforma mido)-1,2, 3,4-tetrahydronaphthalene) was determined in vitro in rabbit platelets and in vivo in rats and guinea-pigs. CIS-19 inhibited in a selective and concentration-dependent manner the aggregation and ATP release reaction of rabbit platelets induced by PAF (4 nM). The IC50 values of CIS-19 on PAF-induced aggregation of washed platelets and platelet-rich plasma were 11.3 +/- 2.7 and 16.8 +/- 3.0 microM respectively. BN52021 also inhibited PAF-induced aggregation of washed platelets with an IC50 value of 11.7 +/- 2.8 microM. CIS-19 inhibited [3H]PAF (4 nM) binding to washed rabbit platelets with an IC50 value of 1.5 +/- 0.2 microM. The concentration-response curve of PAF-induced aggregation of washed platelets was shifted rightwards by CIS-19 with pA2 and pA10 values of 7.1 (6.8-7.3 for 95% confidence limit) and 6.1 (5.8-6.2) respectively. The thromboxane B2 formation of washed platelets caused by AA, collagen or thrombin was not affected by CIS-19 of concentrations below 400 microM. CIS-19 (25 microM) completely blocked PAF-induced, but not collagen- or thrombin-induced [3H]inositol monophosphate formation of washed platelets. When CIS-19 (2.5 and 5 mg/kg) was injected i.v. into the femoral vein, it did not affect the blood pressure of rats, but antagonized PAF (2.5 micrograms/kg, i.v.)-induced hypotensive shock either preventively or curatively. CIS-19 (2.5 and 5 mg/kg) also blocked PAF (50 ng/kg)-induced, but not AA (50 micrograms/kg)-induced, bronchoconstriction in guinea-pigs. It is concluded that CIS-19 is an effective PAF receptor antagonist not only in vitro, but also in vivo.

Adenosine Triphosphate↗
PubMed1993

Possible non-sexual transmission of genital human papillomavirus infections in young women.

Human papillomaviruses were detected by an in vitro enzymatic DNA amplification method in cells obtained from vulvar swabs of 9 of 61 (14.8%) young women without prior experience of sexual intercourse and in 7 of 57 (12.3%) young women with prior experience. The prevalence of human papillomavirus DNA in these two groups of women was not significantly different (x2 = 0.16, p > 0.5; 95% confidence interval -0.165 to 0.215). These results suggest that genital human papillomavirus is not sexually transmitted in all cases and that it may be acquired by modes other than sexual contact.

Adult↗
PubMed1993

Clinical experience and model analysis on beta-2-microglobulin kinetics in high-flux hemodialysis.

Beta-2-microglobulin (beta 2M) is associated with amyloidosis. The study of beta 2M kinetics can provide information on the elimination of this uremic toxin. A beta 2M kinetic model modified from Gotch, considering the volume changes between intracellular, interstitial, and intravascular compartments and the generation stimulation and inhibition during hemodialysis is proposed. The clinical experiments on 8 stable hemodialysis patients treated with polysulfone (F80) and polymethyl methacrylate (PMMA, BK2.1p) 3 times a week were conducted. There was an 18% decrease of beta 2M clearance in the period from 30 to 180 min with a time-averaged beta 2M clearance of 48 ml/min using polysulfone dialyzers (F80). In PMMA dialyzers, there was a 64% decrease of beta 2M clearance from 30 to 180 min with a time-averaged clearance of 56.3 ml/min. During hemodialysis, the generation rate was 0.379 mg/min in polysulfone and 0.828 mg/min in PMMA dialyzers. There was a stimulation generation of 0.309 mg/min in polysulfone and 0.749 mg/min in PMMA during hemodialysis. In conclusion, we provide a beta 2M kinetic model including volume changes, polymerization, generation stimulation, and inhibition that is similar to the human physiological condition. This model can be used for further clinical study.

Blood Flow Velocity↗
PubMed1993

Unintentional carbon monoxide deaths in California from charcoal grills and hibachis.

This study was carried out to determine the annual incidence rate of and factors associated with unintentional deaths due to carbon monoxide (CO) poisoning from charcoal grills/hibachis in California during 1979-1988. A search through the California Master Mortality File was conducted to identify all cases with ICD-9 codes related to unintentional CO deaths. Individual coroners' investigation reports were obtained from 42 counties and evaluated by three evaluators. After excluding miscoded and misclassified cases, 444 deaths were judged to be authentic cases of unintentional CO poisoning. Among them, 59 deaths found to be due to the improper use of charcoal grills/hibachis. An increasing but not statistically significant trend was observed over the 10-year period. The highest rates occurred among males, asians, blacks, and middle-aged (20-39) people. Fifty-four percent of the deaths occurred in motor vehicles and 46% in residential structures.

Accidents↗