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Biomedical subjects

C F Yang

Publications and source records attributed to C F Yang.

At least 19 recordsLinked to original sources
PubMed1992

Transcatheter arterial chemoembolization for hepatocellular carcinoma.

The factors relating to the duration of survival were analyzed for 329 cases of hepatocellular carcinoma (HCC) treated by transcatheter arterial chemoembolization (TACE) between January 1, 1983, and December 31, 1990. The cumulative survival value obtained was slightly higher but not statistically significantly higher in these 329 cases as compared with the 129 cases reported in 1989. This improvement was probably attributable to careful selection of the patients on the basis of the clinical Child's status and to improvement of the superselective angiotechnique used in the present study. The overall cumulative 1-, 2-, and 3-year survival values in this series were 50%, 25%, and 15%, respectively. The median duration of survival was 12.7 months (Kaplan-Meier method). The 1-, 2-, and 3-year survival values determined for 190 patients in Child's group A, for 95 patients in Child's group B, and for 44 patients in Child's group C were 60%, 30%, and 20%; 35%, 20%, and 10%; and 35%, 20%, and 10%, respectively. Analyses were also carried out according to the tumor's type and size, the integrity of the tumor capsule, and the patency of the portal vein. Our results disclosed that a better outcome in terms of the median survival period and the survival value was favored by the following factors: a single lesion measuring less than 5 cm in diameter, an intact capsule, a patent portal vein, and a good clinical status. It is also essential that all patients who have undergone TACE be periodically evaluated by ultrasonography, CT, and angiography to determine whether repeated chemoembolization is necessary.

Adult↗
PubMed1992

Genotype-specific in vitro amplification of sequences of the wild type 3 polioviruses from Mexico and Guatemala.

The extensive nucleotide sequence heterogeneity among independent genotypes of wild polioviruses permits the systematic design of genotype-specific molecular reagents. We have prepared two sets of polymerase chain reaction (PCR) primer pairs specific for the genotype of wild poliovirus type 3 recently endemic to Mexico and Guatemala. Nucleotide sequences of a representative wild type 3 virus isolated in Mexico in 1989 differed from the corresponding Sabin 3 (Leon 12 a1b) sequences at 167 of 900 positions within the VP1 region. From the sequence data, wild virus-specific primer pairs were designed to complement regions of high mismatch (greater than 33%) with Sabin 3 templates. Primer binding sites were spaced along the genome so that the predicted amplification products (142 bp and 163 bp) could be easily resolved electrophoretically from the products generated with our Sabin strain-specific primers (Sabin 1: 97 bp; Sabin 2: 71 bp; Sabin 3: 53 bp). RNAs of all wild type 3 poliovirus isolates from Mexico and Guatemala obtained over a 13-year period (1977-1990) served as efficient templates for amplification of the 142-bp and 163-bp products. Genomic templates derived from vaccine-related polioviruses and most heterologous wild polioviruses were inactive under equivalent reaction conditions. Amplifications generating a 114-bp product with a broadly reacting primer pair, matching highly conserved sequences in the 5'-noncoding region, provided a positive control for the presence in samples of poliovirus (or enterovirus) RNAs. Selective amplification of wild Mexico-Guatemala type 3 poliovirus sequences was obtained with either primer set in reactions containing large stoichiometric excesses (up to 10(6)-fold) of vaccine-related RNAs. We have used wild genotype-specific PCR primer sets to facilitate identification of wild polioviruses present in both clinical and environmental samples.

Amino Acid Sequence↗
PubMed1992

Prenatal diagnosis of intrauterine infection with parvovirus B19 by the polymerase chain reaction technique.

Human parvovirus B19 is a recently recognized cause of fetal hydrops and death. Efforts to characterize the natural history of fetal infection with this virus have been hampered by the lack of sensitive and specific tests for diagnosis in utero. Using the highly sensitive polymerase chain reaction (PCR) assay, we determined the fetal infection status in 56 pregnancies by testing amniotic fluid, fetal serum, and maternal serum for B19 DNA and antibodies. Factors associated with a high risk of B19 infection were fetal disease, exposure to persons with erythema infectiosum, or signs or symptoms of acute B19 infection. Fifteen women (27%) were B19 IgM-positive, a status suggesting recent infection; the positivity of all of the corresponding fetal specimens for B19 DNA in the PCR was indicative of fetal infection. In four of these cases, serial ultrasonographic examinations documented spontaneous resolution of fetal hydrops. Twenty-four women (43%) were IgG-positive and IgM-negative; this pattern suggested prior infection. The PCR gave positive results, consistent with recent maternal infection, in four of these cases. Seventeen women (30%) were IgG-negative and IgM-negative, a pattern suggesting no prior infection; the PCR results in four cases were indicative of a possible early maternal infection or a possible atypical immune response. The PCR is a sensitive and rapid method for the diagnosis of intrauterine infection with human parvovirus B19 and promises to facilitate studies of the natural history and treatment of this infection.

Adolescent↗
PubMed1992

[Computed tomography for evaluation of hepatocellular carcinoma after treatment with transarterial chemoembolization].

Totally 135 series of computed tomography (CT) and angiographic examination were performed in 53 patients with proved hepatoma treated by TAE. CT examination was performed four to six weeks after TAE, and a comparative angiographic examination was performed within three weeks after CT examination. The pictures of CT scanning were read to determine 1). the grading of lipiodol retention inside the tumor, 2). the presence/absence of filling defect in the tumor margins coated by lipiodol, 3). the presence/absence of residual tumor tissue within or surrounding the main tumor, and 4). the presence/absence of developed satellite nodules. In comparison with angiographic findings, CT demonstrated 96.3% specificity and 58.2% sensitivity in the grading of lipiodol filling, and 96.3% specificity and 65.7% sensitivity in the tumor margins of lipiodol coating. However, it was difficult for CT to detect small nodules, especially those less than 1 cm in diameter. We find no statistically significant association between newly developed satellite nodules and grading of lipiodol retention inside the tumor or tumor margins of lipiodol coating. Therefore, when CT pictures reveal filling defect over the margins of the tumor coated by lipiodol or less-than-50% lipiodol filling inside the tumor, repeated angiography and further treatment with TAE are suggested.

Adult↗
PubMed1992

[Differentiation between primary hepatocellular carcinoma and hemangioma on MRI].

Most of the primary hepatocellular carcinoma and hemangioma in TIWI are having low signals. Hemangioma is relatively lower in signal intensity than primary hepatocellular carcinoma, but they are really no so easy compare by bare eye. On the contrary, in T2WI, hemangioma is more brighter than primary hepatocellular carcinoma. So, by compare the variety shows from T1WI to T2WI, we can differentiated between primary hepatocellular carcinoma and hemangioma. By measuring the signal intensity in non-tumor area, there are no marked different in T1WI and T2WI, but hemangioma, as compare with primary hepatocellular carcinoma in signal intensity, is lower in T1WI and much higher in T2WI. Such results are all having statistic significant with p value less than 0.05. In measuring the different in signal intensity or ratio between tumor and non-tumor areas, there were mark different in T2WI and whereas there were no different in T1WI. By using two-point method, the T2-relaxation is measured in twenty eight cases of primary hepatocellular carcinoma and thirteen cases (twenty four lesions) of hemangioma. We found that there were nearly equal in nontumor areas, but there were mark different in T2-relaxation. In comparison with intravenous injection of Gd-DTPA in 10 cases of primary hepatocellular carcinoma and six cases of hemangioma, the latter were having similar dynamic CT appearance. Enhancement of signal intensity was found starting from peripheral part to central area. The primary hepatocellular carcinoma were having none of the above phenomenon. The liver MRI study is still expensive and time consuming.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1992

[MRI of adrenal tumors].

Within a two and half years period, we collected a total of twenty three cases of adrenal tumors diagnosed by MRI. They included: one cystic case, twelve cases (13 lesions) of adenoma, two cases (3 lesions) of hyperplasia, four cases of pheochromocytoma, three cases of metastases, and one case of adenocarcinoma. Except for the case of adrenal cyst which was followed for one and a half years, all the other twenty two cases were proved by operation and pathology. The benign adenoma and hyperplasia were small in size, and had relative isointensities to the liver in the T1WI and the T2WI. On the contrary, the malignant tumors and pheochromocytoma, all had inhomogeneous signal intensities, showed relatively lower in signal intensities in T1WI and higher in T2WI as compared with the liver. In T2WI, the tumor to liver signal intensity ratio of adenoma and hyperplasia were less than 1.80, whereas the malignant tumors and pheochromocytoma were larger than 1.80. In comparing fifteen cases with Gd-DTPA intravenous injection, all of the benign adenoma did not show an increase in signal intensity, but the malignant tumors and pheochromocytoma showed increase in signal intensity. We concluded that we could primarily differentiate the nature of adrenal tumors by their change in signal intensities between T1WI and T2WI, by measuring the tumor to liver signal intensity ratio or by Gd-DTPA IV injection. Today, although adrenal gland MRI examination is more time consuming and expensive, it is more valuable for highly clinically suspected adrenal lesions with equivocal results after CT or sonogram study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1992

[Acute abdomen with intraperitoneal bowel perforation-demonstration by CT scan].

Ninety-eight cases of surgically proved bowel perforation in VGH-Kaohsiung within one year were reviewed. Among them, 25 patients received abdominal CT scans before operation. Free gas or fluid could be demonstrated with CT scan in 80% of cases though sometimes the fluid was too scanty to be well recognized. Local abscess formation with or without tumor mass lesion (n = 3), local fluid accumulation (n = 1) and negative CT findings (n = 1) constituted the remaining 20% of cases. The recognition of perforation sites depended on direct evidences of perforation such as ulceration, abscess formation and tumor mass lesion (32%), or indirect evidences including hematoma formation, dependent extraluminal gas accumulation and phlegmonous reaction (12%). An inexplicable localized extraluminal fluid accumulation might also suggest a possibility of hollow organ perforation and lead to the recognition of perforation site in the absence of free gas (4%). Absence of extraluminal fluid or gas can not completely rule out the possibility of hollow organ perforation (4%). Massive free air, especially with an air-fluid level, suggested a possibility of upper abdominal perforation. The perforation hole located at the anterior wall of stomach produced more free gas than that located at posterior wall. Air-fluid levels could never be identified in the cases of lower gastrointestinal perforations. Local bowel wall thickening and the distribution of free gas contributed little to the recognition of perforation site. Extravasation of oral contrast media sometimes led to the diagnosis of gastrointestinal perforation but was not necessary to be noted around the perforation hole and did little contribution to the perforation site recognition.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen, Acute↗
PubMed1991

Detection and identification of vaccine-related polioviruses by the polymerase chain reaction.

We have used the polymerase chain reaction (PCR) to obtain sensitive detection and identification of poliovirus RNA genomes. Primer pairs were designed to permit identification of each Sabin poliovaccine strain by the electrophoretic mobilities of the amplified DNA products (Sabin 1: 97 bp; Sabin 2: 71 bp; Sabin 3: 44 bp). The compositions of samples containing mixtures of vaccine strains could be readily determined by PCR. When the amplified products were visualized by ethidium bromide fluorescence, as few as 250 genomic copies in the original sample could be detected. When PCR was used in combination with strain-specific 32P-labeled oligonucleotide probes, the limit of detection was less than or equal to 2.5 poliovirus genomes, exceeding the sensitivity of poliovirus isolation in cell culture by at least 100-fold. PCR amplifications may be performed on virion RNAs extracted directly from clinical specimens, potentially eliminating the requirement for virus isolation in routine identifications while yielding reliable results within 8 h.

Base Sequence↗
PubMed1991

[MRI of white matter pathways].

CT scan shows some relatively large white matter pathways such as corpus callosum or internal capsule, while MRI provides more sophisticated display of cerebral white matter pathways, based partly on difference in the water content, which improves contrast resolution of structures that cannot be appreciated on CT scanning. The white matter shows slightly high signal intensity in T1WI as compared with the peripheral gray matter. In contrast, it is relatively low signal intensity in long TR sequence. The signal intensity is correlated with myelination, density of myelin fibers and possibly iron deposition. In this study, we collected data on 30 patient, aged from 3 to 60 years average 38 years of normal MRI study of the brain. We routinely obtained T1 Weighted image (T1WI, TR/TE 500-600/20 msec), dual echoes image of proton density image (PDI, TR/TE 2000-3000/20 msec), T2 weighted image (T2WI, TR/TE 2000-3000/80-120 msec), in axial and coronal sections. In some cases sagittal section was also imaged. We identified the white matter pathways based on the data from the axial and coronal sections of 2 autopsy specimens. We also consulted several textbooks and literature reviews of gross and MRI anatomy. The following white matter pathways could be clearly observed on MRI: 1. Projection fibers: corona radiata and internal capsule; 2. Commissural fibers: corpus callosum and anterior commissure; 3. Associated fibers: superior occipito-frontal fasciculus, superior longitudinal fasciculus, ucinate fasciculus, cingulum bundle, optic radiation fornix and mammillothalamic tract.

Adolescent↗
PubMed1990

Transcriptional induction of purple membrane and gas vesicle synthesis in the archaebacterium Halobacterium halobium is blocked by a DNA gyrase inhibitor.

We have investigated the expression of the bacteriorhodopsin gene (bop) and the gas vesicle protein gene (gvpA) in the extremely halophilic archaebacterium Halobacterium halobium, using primer-directed reverse transcription of RNA to quantify message levels. The level of gvpA gene transcript was found to increase about 5-fold from early to mid-logarithmic growth phase, while the level of bop gene transcript increased about 20-fold from mid-logarithmic to stationary phase. Transcriptional induction of both the gvpA and bop genes was significantly reduced by aeration and almost completely blocked by the DNA gyrase inhibitor novobiocin.

Archaeal Proteins↗
PubMed1990

[Magnetic resonance imaging of ovarian cystic teratoma].

Two patients with ovarian cystic teratoma were imaged using real-time ultrasound and 1.0-T magnetic resonance imaging (MRI) devices. The ultrasound appearance of cystic teratoma varies with the internal contents. If bone or teeth is present, highly echogenic foci with posterior shadow will be identified. The cysts may contain solid areas, septa and fluid-fluid levels. The dermoid cyst filled with fat showing characteristic echogenic appearance might confused with the pelvic fact tissue. MRI is well suited to the evaluation of pelvic disorders. The T1 and T2 relaxation times in different tissues might present with different signal intensities by changing the pulse sequences. Fat, with its relatively short T1 and long T2 times, appears bright on the T1-weighted images (short TE and TR) and T2-weighted images (long TE and TR). However, old hemorrhage has the MRI characteristics of short T1 and long T2 times as fat. The inversion recovery sequence with short inversion time (STIR) will suppress signal from fat tissue and this is of particular value in differentiating dermoid from hemorrhagic cyst. MRI is quite efficient in cases where ultrasound study is equivocal or difficult in the technique.

Adult↗
PubMed1989

Analysis of insertion mutants reveals two new genes in the pNRC100 gas vesicle gene cluster of Halobacterium halobium.

The archaebacterium, Halobacterium halobium, achieves buoyancy through synthesis of intracellular gas-filled vesicles. The plasmid-encoded gene (gvpA) specifying the major structural gas vesicle protein has previously been cloned and sequenced allowing the analysis of high-frequency mutations to the vesicle negative phenotype. Among eighteen gas vesicle mutants analyzed, four were observed to contain insertion elements 0.2 to 2 kb upstream of the structural gene. To explain the phenotype of these mutants, the upstream area was analyzed by DNA sequencing and transcriptional mapping. This analysis showed the presence of two open reading frames, gvpD and gvpE, which are of opposite transcriptional orientation to gvpA (gene order gvpA-D-E). gvpD begins 201 nucleotides from the gvpA structural gene and is 1608 nucleotides long while gvpE begins two nucleotides from the 3'-end of gvpD and is 573 nucleotides long. Primer extension analysis showed the occurrence of divergent promoters in the gvpA-gvpD intergenic region with the transcription start sites separated by 109 nucleotides. The sites of three insertion sequences in gas vesicle mutants mapped within gvpE while the fourth insertion site mapped near the N-terminal coding region of gvpD. Homology between the gvpDE gene region and a chromosomal site in a H. halobium NRC-1 derivative and in several other Halobacterium strains was identified by Southern hybridization.

Amino Acid Sequence↗
PubMed1989

Transcatheter arterial chemoembolization for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) was treated with transcatheter arterial chemoembolization (TACE) in a sample of 129 patients. The cumulative survival rate was 49% at 1 year and 22% at 2 years. The median survival time was 11.9 months. The survival rates at 1 year of 84 patients in Child's group A and 27 in Child's group B were 56% and 40%; out of 52 HCC patients with portal vein patent and 77 with portal vein invasion 75% and 40% survived, and the 1-year survival rates for 33 HCC patients with capsule intact, 14 with capsule broken and 82 with no capsule were 85%, 65% and 40% respectively. From the above results there were statistically significant differences in survival time in those with good clinical performance status by Child's classification, those showing patency of the portal vein and those where the capsule was present. Therefore, we would like to recommend, TACE of HCC in well-selected patients presenting with good clinical status, patency of the portal vein and without broken capsule, in order to achieve better clinical results.

Adult↗
PubMed1989

Reversible dedifferentiation and redifferentiation of a melanized cell line from a goldfish tumor.

We reported previously the isolation of a melanized cell line that can undergo reversible dedifferentiation and redifferentiation. A heavily pigmented cell line, designated as P15, originally isolated by fish serum-induced melanization of some GEM 81 cells, cloned and serially passaged in fish serum medium, became noticeably less pigmented after several months in fetal calf serum medium and completely unpigmented after another year in the same medium. Addition of fish serum to the medium of this dedifferentiated cell line, designated P15D, induced pigmentation within a week. This re-induced pigmented cell line, designated as P15DI, became unpigmented when cultured in fetal calf serum medium for one month. We report here that the dedifferentiation of P15 occurs in two stages. One week after withdrawal of fish serum, the specific activity of tyrosinase of the culture dropped by approximately 70% and remained at this reduced level for at least one month. After one year, the specific activity of tyrosinase had dropped to a barely detectable level and the culture became completely unpigmented (P15D). Electron microscopic studies showed that the P15D cells have no melanosomes, probably no large vesicles for melanosome formation, but some dopa-positive trans-Golgi network (TGN). Addition of fish serum to the growth medium of P15 cultures led to a steady increase in the specific activity of tyrosinase, detectable after one day. There was also an increase in the amount of dopa-positive TGN within one day. Melanosomes first appeared after three days and became numerous after one week. Upon removal of fish serum, these re-induced cells (P15D1) underwent a rapid decrease in the specific activity of tyrosinase, reaching, after eight days, the basal level seen in P15D cells. We also report that a protein designated as p75 (Mr approximately 75,000), previously shown to be associated with melanosomes in two melanized cell types of goldfish origin, is present in all melanized cell lines, including P15 and P15DI but absent in unmelanized cell lines, including P15D.

Animals↗
PubMed1988

Inhibitory effect of l-ascorbic acid on the growth of astrocytes in cell culture.

The effect of l-ascorbic acid on the growth of astrocytic cells in culture was investigated. l-Ascorbic acid produced a concentration-dependent reduction of the growth of astrocytes, both in normal and tumor cells. The effect of l-ascorbic acid was similar to that of the relative acidification of the medium, except in treated concentrations greater than 10(-6) M. The effects produced by both l- and d-forms of ascorbic acid were the same. The inhibitory effect of l-ascorbic acid at greater concentrations was partially prevented by oxidized glutathione and increased by the large concentration of reduced glutathione. This result suggests that l-ascorbic acid possesses the ability to inhibit the growth of astrocytic cells in culture through the acidification of the medium at small concentrations and/or the antioxidative properties of this compound at larger concentrations.

Animals↗