Biomedical subjects

C F Yang

Publications and source records attributed to C F Yang.

At least 73 records · Page 4Linked to original sources

PubMed1996

Group-specific identification of polioviruses by PCR using primers containing mixed-base or deoxyinosine residue at positions of codon degeneracy.

We have developed a method for differentiating polioviruses from nonpolio enteroviruses using PCR. A pair of panpoliovirus PCR primers were designed to match intervals encoding amino acid sequences within VP1 that are strongly conserved among polioviruses. The initiating primer hybridizes with codons of a 7-amino-acid sequence that has been found only in polioviruses; the second primer matches codons of a domain thought to interact with the cell receptor. The panpoliovirus PCR primers contain mixed-base and deoxyinosine residues to compensate for the high degeneracy of the targeted codons. All RNAs from 48 vaccine-related and 110 wild poliovirus isolates of all three serotypes served as efficient templates for amplification of 79-bp product. None of the genomic sequences of 49 nonpolio enterovirus reference strains were amplified under equivalent reaction conditions. Sensitivities of poliovirus detection were as low as 100 fg (equivalent to approximately 25,000 genomic copies or 25 to 250 PFU) when the amplified products were visualized by ethidium bromide fluorescence. These degenerate PCR primers should aid in the detection of all polioviruses, including those wild poliovirus isolates for which genotype-specific reagents are unavailable.

Amino Acid Sequence↗

PubMed1996

Azygos blood flow in cirrhosis: measurement with MR imaging and correlation with variceal hemorrhage.

PURPOSE: To evaluate magnetic resonance (MR) measurement of azygos blood flow (ABF) in assessment of risk of variceal hemorrhage in cirrhosis. MATERIALS AND METHODS: ABF in 50 patients with cirrhosis and 20 healthy control subjects was evaluated with phase-contrast cine MR imaging at the transaxial subcarinal plane. Group 1 included nine patients with cervical-drainage varices draining into brachiocephalic vein; group 2 included 41 patients with varices draining into azygos vein and was subdivided as group 2A, 15 patients with variceal hemorrhage, and group 2B, 26 without variceal hemorrhage. RESULTS: Azygos flow rate and velocity were increased in patients compared with that in control subjects. ABF in group 2A was faster than that in group 2B (cutoff, 15 cm/sec; sensitivity, 80%; specificity, 89%). Group 1 had ABF close to that of group 2B, but variceal hemorrhage occurred in seven of nine patients in group 1 versus 15 of 41 patients in group 2 (78% vs 37%; P = .029). CONCLUSION: Patients with cirrhosis with cervical-drainage varices or ABF greater than 15 cm/sec may have higher risk for variceal hemorrhage.

Azygos Vein↗

PubMed1996

Adenosquamous carcinoma and schneiderian papilloma-like lesion in a mature cystic teratoma of the ovary: a case report.

Malignant transformation is uncommon in the mature cystic teratoma of ovary, in which adenosquamous carcinoma is even rarer. It seldom combines with papillary lesion, like schneiderian papilloma of upper airway. We report such a rare case of mature cystic teratoma undergoing malignant change, with the pictures of both adenosquamous carcinoma and schneiderian papilloma.

Carcinoma, Adenosquamous↗

PubMed1996

Computed tomography in the diagnosis of organic bowel obstruction.

BACKGROUND: This study examined the usefulness of computed tomography (CT) scan for cases of organic intestinal obstruction, with two simple criteria. METHODS: One hundred and thirteen patients with clinical suspicion of bowel obstruction were referred for CT scans. A line was drawn between the dilated proximal, and the collapsed distal bowels. A careful search was conducted on this line for obstructive lesions. The results were reported to be organic obstruction if there was an abrupt change of caliber (Criterion I) or a soft tissue mass around the dilated bowel (Criterion II). The judgement based on the CT findings. RESULTS: Eighty-eight cases proved to have bowel obstruction. With Criterion I, the sensitivity was 59.1%, and specificity, 88% with Criterion II, the sensitivity was 56.3% and specificity 100%. If either of them was considered to be a positive sign of organic obstruction, the sensitivity was 100%, the specificity 88% and the accuracy 97.3%. The nature of the obstructions were precisely predicted in 76 patients (86%). CONCLUSIONS: With these two simple criteria, CT scan can achieve high accuracy and is a recommendation in virtually every instance when intestinal obstruction is suspected.

Adult↗

PubMed1996

Experience with transjugular intrahepatic portosystemic shunts for gastroesophageal variceal bleeding.

BACKGROUND: Variceal bleeding is a major life-threatening complication of cirrhosis of the liver. Transjugular intrahepatic portosystemic shunts (TIPS) have been accepted as an effective method for portal decompression. Experiences here with the use of TIPS for control of gastroesophageal variceal bleeding is presented. METHODS: Sixteen TIPS procedures were performed for 15 patients who suffered from intractable gastroesophageal variceal bleeding. Nine cases (60%) were hepatitis-related cirrhosis of liver, four (27%) were alcoholic liver cirrhosis and two were cryptogenic in origin. Liver function tests revealed four patients were Child-Pugh's classification A, five were B and six, C. Twelve cases had received failed endoscopic management of varices; and one patient had recurrent variceal bleeding after devascularization. TIPS procedure was performed electively in nine cases and, as an emergency in six cases. RESULTS: Fifteen of the 16 TIPS procedures attempted were successfully performed. The technically successful rate was 94% (15/16), but two cases with successful TIPS procedure expired at the end of the procedure from hypovolemic shock and acute respiratory distress, respectively; thus the completely successful rate was 81% (13/16), The initial bleeding control rate was 83% (5/6) for the six patients with active bleeding. Portal venous pressure was significantly decreased from 30.8 +/- 5.8 mmHg before TIPS to 21.7 +/- 6.0 mmHg after the procedure (P < 0.01) and the porto-systemic pressure gradient also significantly decreased from 23.0 +/- 3.6 mmHg to 11.9 +/- 2.7 mmHg after TIPS (P < 0.01). Recurrent variceal bleeding was noted in four patients (33%) and that was managed by percutaneous transluminal angioplasty (PTA) of shunt, placement of additional stent, second TIPS procedure and a devascularization operation. Hepatic encephalopathy was noted in three patients (25%) after TIPS. CONCLUSIONS: TIPS is an effective method to control variceal bleeding caused by portal hypertension, especially when endoscopic or surgical management has failed or is contraindicated.

Adult↗

PubMed1996

Langerhans' cell histiocytosis (histiocytosis-X) in a women with typical ultrastructure of Birbeck's granule: a case report.

A 28-year-old woman was admitted to our hospital with the chief complaint of progressive gingival swelling with easy bleeding and loosening of teeth for about two years. The liver and spleen were not enlarged and there were no lymphadenopathy. The hemogram was normal. The skull X-ray showed floating teeth. CT scan of face showed destructive bony lesions over maxilla and left mandible with adjacent soft tissue swelling. Pathologic examination of the gingiva revealed that the oral mucosal tissue was heavily infiltrated with histiocyte-like Langerhans' cells. The Langerhans' cells showed positive immunostain for S-100 protein. Under electron microscope, ultrastructure of the Langerhans' cells revealed typical intracytoplasmic tennnis racquet-shaped structure with a central zipper-like striation (Birbeck's granules). Langerhans' cell histiocytosis was diagnosed. She received rdiotherapy with a total dose of 1,000 cGy in fractions and oral chemotherapeutic drugs. Painful gingival swelling subsided gradually. She was followed at our OPD for the past 10 months and there was no evidence of local recurrence. Langerhans' cell histiocytosis is a rare disease. The relevant literature about its distinct pathologic features, clinical course and treatment is reviewed.

Adult↗

PubMed1995

Specific binding of the biradical analog of neocarzinostatin chromophore to bulged DNA: implications for thiol-independent cleavage.

The enediyne anticancer antibiotic neocarzinostatin chromophore generates a single, site-specific break at a bulge in DNA in a thiol-independent reaction, involving intramolecular drug activation under general base catalysis [Kappen, L. S., & Goldberg, I. H. (1993) Biochemistry 32, 13138-13145]. As part of an effort to elucidate the three-dimensional structure of the active complex formed between the labile drug and bulged DNA, we have studied the binding of stable drug products generated in the course of the cleavage reaction with oligodeoxynucleotides containing the bulged structure. By use of fluorescence quenching, we have found that one drug product, which is also formed in the absence of bulged DNA and most closely resembles the biradical intermediate in the cleavage reaction, specifically binds bulged DNA with a Kd in the low micromolar range and competitively inhibits the cleavage reaction. Other drug products, including one formed only in the presence of bulged DNA, fail to bind to the bulged DNA. Implications of these results for the proposed mechanism of bulge-specific cleavage and for the role of the DNA bulge in generating a unique drug product are discussed.

Base Sequence↗

PubMed1995

Identification of vaccine-related polioviruses by hybridization with specific RNA probes.

We developed RNA probes for the identification of poliovirus isolates by blot hybridization. Two sets of vaccine strain-specific probes were prepared. They complemented variable genomic domains within (i) the 5'-untranslated region and (ii) the amino-terminal codons of VP1. An enterovirus group probe (EV/5UT) matching highly conserved 5'-untranslated region sequences was used to estimate the quantities of poliovirus (or enterovirus) RNA in the samples. Poliovirus sequences amplified from Sabin strain virion RNA templates by PCR were inserted into the pUC18 plasmid vector. The antisense PCR primer for each probe set contained sequences encoding a T7 promoter. Hybrids were detected by a sensitive nonisotopic method. RNA probes were labeled by incorporation of digoxigenin-uridylate into the transcripts. The binding of probe to immobilized poliovirus RNAs was visualized by hydrolysis of the chemiluminescent substrate 4-methoxy-4-(3-phosphate-phenyl)-spiro-(1,2-dioxetane-3,2'-adamant ane) catalyzed by alkaline phosphatase conjugated to anti-digoxigenin (Fab) fragments. The specificities of the probes were evaluated with a panel of poliovirus isolates that had previously been characterized by sequence analysis. The RNAs of vaccine-related isolates hybridized with the appropriate probe sets. Wild polioviruses representing a broad spectrum of contemporary genotypes were recognized by the inabilities of their genomes to form stable hybrids with the Sabin strain-specific probes.

Base Sequence↗

PubMed1995

Carcinosarcoma of the salivary gland on CT.

Three cases of carcinosarcoma of the salivary gland, two in the submandibular gland, and one in the parotid, were investigated with CT and exhibited a variety of findings. The density of the tumors was lower than that of normal submandibular tissue. A calcification was found in one case. One case showed extensive lymphadenopathy. The parotid lesion had low central density with an enhancing margin.

Aged↗

PubMed1995

Mesoblastic nephroma: a case report.

Mesoblastic nephroma is a rare tumor of kidney characterized by interlacing bundles of spindle mesenchymal cells. The tumor usually occurs in the newborn, and scarcely in the old child. In this article, the authors report a case of an unusual age, a 12-year-old boy, with mesoblastic nephroma which was found by routine physical examination.

Child↗

PubMed1994

Transcatheter arterial embolization with or without cisplatin treatment of hepatocellular carcinoma. A randomized controlled study.

BACKGROUND: This randomized controlled study was objectively designed to evaluate the utility cisplatin (50 mg) in transcatheter arterial embolization (TAE) for treatment of hepatocellular carcinoma (HCC). METHODS: From May 1991 to July 1993, 46 patients were included in the study. All had a pathologic verification of HCC. Clinically, all of the patients were considered inoperable. However, these patients satisfied eligibility criteria for TAE. The patients were divided into two groups by random sampling. In group I, 22 patients received TAE with the regimen of cisplatin (50 mg) mixed with Lipiodol 5-15 ml followed by gelfoam pieces. In group II, 24 patients, as a controlled group, used the regimen of Lipiodol and gelfoam (Spongostan Film, Ferrosan, Denmark) pieces only, without adding any anticancer drug. The two groups were evaluated by a series of imaging studies and various clinical examinations before and after TAE. Subsequently, TAE was performed every 2 or 3 months for all patients until there was no visible tumor, or the patient could not sustain further TAE, or the patient died. RESULTS: In group I, TAE was administered 61 times (average 28 times for each patient), and in group II, 73 times (average 3 times for each patient). The 1-year and 2-year survival rates of group I were 52.5% and 26.2%, and group II were 72.5% and 39.5%. Statistically, there was no significant difference in survival curves and survival rates between these two groups. Tumor response rate of group I was 68% (15/22) and group II was 67% (16/24). There was no significant difference in tumor response between these two groups. The liver and renal function studies after TAE also showed no significant difference between these two groups. CONCLUSIONS: Based on this controlled study, the authors conclude that the addition of cisplatin does not enhance the therapeutic effect of TAE for treatment of HCC.

Adult↗

PubMed1994

Molecular dynamics simulation of a leucine zipper motif predicted for the integrase of human immunodeficiency virus type 1.

We have used the molecular dynamics (MD) simulation package AMBER4 to search the conformation of a peptide predicted as a leucine zipper motif for the human immunodeficiency virus type 1 integrase protein (HIV IN-LZM). The peptide is composed of 22 amino acid residues and its location is from Val 151 to Leu 172. The searching procedure also includes two known alpha-helices that served as positive controls--namely, a 22-residue GCN4-p1 (LZM) and a 20-residue poly (L-alanine) (PLA). A 21-residue peptide extracted from a cytochrome C crystal (CCC-t) with determined conformation as a beta-turn is also included as a negative control. At the beginning of the search, two starting conformations--namely, the standard right-handed alpha-helix and the fully stretched conformations--are generated for each peptide. Structures generated as standard alpha-helix are equilibrated at room temperature for 90 ps while structures generated as a fully stretched one are equilibrated at 600 K for 120 ps. The CCC-t and PLA helices are nearly destroyed from the beginning of equilibration. However, for both the HIV IN-LZM and the GCN4-p1 LZM structures, there is substantial helicity being retained throughout the entire course of equilibration. Although helix propagation profiles calculated indicate that both peptides possess about the same propensity to form an alpha-helix, the HIV IN-LZM helix appears to be more stable than the GCN4-p1 one as judged by a variety of analyses on both structures generated during the equilibration course. The fact that predicted HIV IN-LZM can exist as an alpha-helix is also supported by the results of high temperature equilibration run on the fully stretched structures generated. In this run, the RMS deviations between the backbone atoms of the structures with the lowest potential energy (PE) identified within every 2 ps and the structure with the lowest PE searched in the same course of simulation are calculated. For both the HIV IN-LZM and the GCN4-p1 LZM, these rms values decrease with the decrease of PE, which indicates that both structures are closer in conformations as their PEs are moved deeper into the PE well.

Amino Acid Sequence↗

PubMed1994

The clinicopathological correlation of epithelial subtyping in thymoma: a study of 112 consecutive cases.

The clinicopathological features of 112 thymomas collected from the surgical pathological files of Taipei Veterans General Hospital from 1961 to 1991 were investigated to determinate the clinical efficacy of epithelial subtyping. All thymomas were categorized based on the Müller-Hermelink system into three subtypes: cortical thymoma, mixed thymoma, and medullary thymoma. The former was further subclassified into organoid thymoma, conventional cortical thymoma, and well differentiated thymic carcinoma (WDTC) according to the systems of Pescarmona and Kirchner. The association of each subtype with sex, age at diagnosis, clinical stage, presence of myasthenia gravis, and length of survival was studied. As classified by the Müller-Hermelink system, the cortical thymomas as a whole tended to occur in younger patients and were more frequently associated with myasthenia gravis than the medullary thymomas. The cortical thymomas also showed a propensity to be invasive in nature, whereas the medullary thymomas generally behaved as benign tumors. Further subclassification of cortical thymomas into organoid thymoma, conventional thymoma, and WDTC did not provide more information about clinical behavior. By Kaplan-Meier's actuarial survival analyses none of the epithelial subtypes displayed a statistically significant influence on prognosis. It is concluded that staging remains the most important factor affecting the patient's outcome. Because of the existence of many intermediate forms and the deficiency of clinical relevance, the subclassification of cortical thymomas should be interpreted as a morphological continuum rather than as distinct histological variants.

Adolescent↗

PubMed1994

Mouse neurovirulence determinants of poliovirus type 1 strain LS-a map to the coding regions of capsid protein VP1 and proteinase 2Apro.

Poliovirus type 1 strain LS-a [PV1(LS-a)] is a OV variant adapted to mice by multiple passages through mouse and monkey tissues. To investigate the molecular basis underlying mouse neurovirulence of PV1(LS-a), a cDNA of the viral genome containing nucleotides 112 to 7441 was cloned, and the nucleotide sequence was determined. Compared with that of the mouse avirulent progenitor PV1(Mahoney), 54 nucleotide changes were found in the genome of the PV1(LS-a) virus, resulting in 20 amino acid substitutions in the virus polyprotein. Whereas the nucleotide changes were scattered throughout the genome, the amino acid substitutions were largely clustered in the capsid proteins and, to a certain extent, in the virus proteinase 2Apro. By in vitro mutagenesis, PV1(LS-a)-specific capsid mutations were introduced into a cDNA clone of PV1(Mahoney). We show that neither the individual amino acid mutations nor combinations of mutations in the region encoding VP1 conferred to PV1(Mahoney) the mouse-adapted phenotype of PV1(LS-a). Chimeric cDNA studies demonstrated that a recombinant type 1 virus containing the PV1(LS-a) sequence from nucleotide 2470 to nucleotide 3625 displayed a neurovirulent phenotype in mice. Further dissection of this region revealed that mouse neurovirulence of PV1(LS-a) was determined by multiple mutations in regions encoding both viral proteinase 2Apro and capsid protein VP1. The mouse neurovirulent viruses, PV1(LS-a), W1-M/LS-Pf [nucleotides 496 to 3625 from PV1(LS-a)], and W1-M/LS-NP [nucleotides 2470 to 3625 from PV1(LS-a)], showed increased sensitivity to heat treatment at 45 degrees C for 1 h. Surprisingly, the thermolabile phenotype was also displayed by a recombinant of PV1(Mahoney) carrying a PV1(LS-a) DNA fragment encoding the N-terminal portion of 2Apro. This suggests that base substitutions in the region encoding 2Apro affected capsid stability, thereby contributing to the neurovirulence of the virus in mice.

Animals↗

PubMed1994

Use of quantitative CT to predict postoperative lung function in patients with lung cancer.

PURPOSE: To evaluate the effectiveness of quantitative computed tomography (CT) for predicting postoperative lung function in patients with lung cancer. MATERIALS AND METHODS: Preoperative spirometry and conventional CT of the chest were performed in 38 patients. A postprocessing CT program was applied to quantitate the volume of whole-lung parenchyma with attenuations of -500 to -910 HU; this was defined as total functional lung volume (TFLV). The regional functional lung volume (RFLV) of the lobes or lung to be resected was quantitated separately. CT-predicted postoperative forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were derived by multiplying the preoperative spirometry values by (1 - RFLV/TFLV). RESULTS: CT-predicted values correlated well with postoperatively measured results (FEV1: r = .93, P < .001; FVC: r = .86, P < .001) in patients who underwent pneumonectomy or lobectomy, regardless of the patient's preoperative ventilation status. CONCLUSION: This method is effective in the prediction of postoperative FEV1 and FVC in patients undergoing pulmonary resection.

Aged↗

PubMed1994

The study of health effects of vinyl chloride air pollution on population.

A series of indicators, including serum lysozyme activity, G-banding chromosome aberration (G-banding CA) analysis, sister chromatid exchanges (SCEs), chromosome aberration (CA), T-lymphocyte transformation rate (TcTR), gamma-GT, GPT and AKP, were employed in the present survey among occupationally vinyl chloride (VC) exposed workers and inhabitants living in VC polluted area in a polyvinyl chloride (PVC) factory. The results showed that the serum lysozyme (S-LZM) activities in Group 3 (adult inhabitants exposed to 0.20 mg/m3 VC for at least 8 years), Group 2 (workers exposed to 4.1 mg/m3 for at least 7 years occupationally), Group 1 (workers exposed to 25.7 mg/m3 for at least 2 years) were significantly higher than control. G-banding CA analysis showed that the total chromosome breakage rates in both Groups 1 and 2 were higher, but no difference existed between Group 3 and control. Only Group 1 was observed having higher SCEs, CA level and lower TcTR than control. AKP levels in Groups 1 and 2 were higher than control, but no gamm-GT and GPT differences were found among groups. The study also suggests that G-banding CA analysis is more sensitive than CA and SCEs.

Adolescent↗

PubMed1993

A spectrophotometric assay for alpha-ketoaldehydes using horse liver alcohol dehydrogenase.

alpha-Ketoaldehydes have been extensively employed as reagents for the chemical modification of arginine residues in proteins, and to probe for putative anion recognition sites. A major disadvantage in their use is instability, as alpha-ketoaldehydes are prone to hydration, oxidation, and polymerization. These reagents are typically supplied as the aldehyde hydrates which are relatively stable, but must be purified and standardized prior to analytical use. The known chemical, spectroscopic, and enzymatic methods for quantitating alpha-ketoaldehydes are not practical for routine analysis due principally to their high detection limits and sensitivity to interfering substances. Surprisingly, alpha-ketoaldehydes have not been reported as substrates for the alcohol dehydrogenases. We have discovered that phenylglyoxal and several related alpha-ketoaldehydes are good substrates for horse liver alcohol dehydrogenase (HLADH). The second order rate constants (kcat/Km) are within a factor of 10 of that for the reduction of acetaldehyde, a known good substrate for HLADH. The enzymatic reduction reaction is stoichiometric with the oxidation of NADH, resulting in a rapid, convenient, and sensitive method for the spectrophotometric quantitation of alpha-ketoaldehydes, with a submicromolar detection limit for phenylglyoxal. The sole product of phenylglyoxal reduction has been identified as alpha-hydroxyacetophenone. The ketone functional group is not reduced, and the enzymatic reaction is essentially irreversible as alpha-hydroxyacetophenone is not oxidized to phenylglyoxal by HLADH in the presence of NAD+.

Acetaldehyde↗

PubMed1993

Distribution of wild type 1 poliovirus genotypes in China.

Poliomyelitis remains an important public health problem in China. Most cases and outbreaks are associated with wild type 1 polioviruses. To obtain an overview of type 1 poliovirus transmission in China, partial genomic sequences were compared for 24 case isolates from 12 provinces. Because polioviruses evolve rapidly during infection of humans, the genetic relationships among isolates provide a measure of the extent of epidemiologic linkage among cases. The observed genetic relationships were complex: six different genotypes, apparently derived from five separate endemic origins, were found. One genotype was recombinant, having noncapsid sequences derived from the Sabin type 1 vaccine strain and capsid sequences derived from a genotype indigenous to several northern and eastern provinces. Some isolates from geographically separate provinces were closely related; other isolates were related to wild polioviruses found in neighboring countries. The combination of epidemiologic and virologic analyses may facilitate the development of more effective strategies for poliomyelitis eradication.

Base Sequence↗