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Biomedical subjects

W L Chen

Publications and source records attributed to W L Chen.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Electron microscopic cytochemistry studies on membrane-bound organelles of Trichomonas hominis].

This paper presents the results of an electron microscopy cytochemistry study on the membrane-bound organelles of Trichomonas hominis. Acid phosphatase (ACP) and cytidine monophosphatase (CMPase) were located in the primary lysosomes, digestive vacuoles, as well as in the parabasal body stacks, being usually in its mature surface sacs. Thiamine pyrophosphatase (TPPase) and nicotinamide adenine dinucleotide phosphatase (NADPase) were found in the saccules, being on the mature surface and in the intermediate saccules of parabasal body stacks, respectively. The reactive products of peroxidase (POase) were seen only in the digestive vacuoles. Cytochrome oxidase (COase) and catalase (Cat) reactions were both negative. It is suggested that T. hominis lacks mitochondrion and microbody but possesses hydrogenosome. The parabasal body, endoplasmic reticulum and hydrogenosome were stained well with the U-Pb-Cu impregnation technique.

Animals↗
PubMed1990

Identification of rat liver glutathione S-transferase Yb subunits by partial N-terminal sequencing after electroblotting of proteins onto a polyvinylidene difluoride membrane from an analytical isoelectric focusing gel.

Rat liver glutathione S-transferases were partially purified using S-hexyl glutathione affinity chromatography, followed by native isoelectric focusing employing a pH 7-11 or pH 3-10 gradient. Proteins were excised and eluted from the gel for determination of subunit composition using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In separate experiments, isoelectric focusing gels were equilibrated with a sodium dodecyl sulfate-containing buffer at high pH, and proteins on the gel were electroblotted onto a polyvinylidene difluoride membrane, utilizing graphite plates as electrodes. The membrane-bound proteins were visualized by Coomassie Brilliant Blue staining. The protein bands were then excised from the membrane and inserted into a gas phase sequenator for direct sequencing. N-Terminal sequences thus determined were compared with published cDNA sequences. The isoelectric points (pIs) and positions on the isoelectric focusing gel of Yb1Yb1, Yb1Yb2 and Yb2Yb2 subunits were determined. We have also located on the pH 3-10 focusing gel an N-terminal blocked glutathione S-transferase which has a molecular weight similar to Yb subunits.

Amino Acid Sequence↗
PubMed1990

The differential diagnosis of benign and malignant bony lesions in bone scanning. Using the ratio of radiouptake at different times.

For the evaluation of bony metastases in cancer patients, bone scanning has become an important tool, but some limitations exist. One of these is the differential diagnosis of benign and malignant bony lesions, in which bone scanning shows one or more lesions in the spine. To help solve this, bone scintigraphy was performed 4 and 24 hours after intravenous injection of Tc-99m MDP; the ratio of radiouptake in the lesion and normal spine was measured as 24-hr/4-hr (T/F) ratio. Fifty-four patients with an average age of 56 years were studied and divided into two groups. Group A included 34 patients (17 women and 17 men) with bony metastases. Group B included 20 patients (8 women and 12 men) with radiographically proven benign bony lesions and no evidence of cancer. An LFOV Elscint Apex 400 digital gamma camera and an Informatek Simis 5 nuclear minicomputer were used. The results showed that the T/F ratio of Group A was 1.3 +/- 0.15 (mean +/- SD) and that of Group B was 1.0 +/- 0.12 (mean +/- SD). The P value was less than 0.001. We conclude that the ratio of radiouptake of lesions and normal spine at 24 and 4 hours may be a reliable method of differentiating benign bony lesions from malignant lesions.

Bone Diseases↗
PubMed1990

Flow cytometric DNA-ploidy as a prognostic indicator in oral squamous cell carcinoma.

In an attempt to evaluate the significance of DNA-ploidy as an objective prognostic indicator of oral squamous cell carcinoma, a retrospective analysis of 70 paraffin-embedded specimens using flow cytometry was performed. Forty-one patients (58.6%) had aneuploid tumors and 29 patients (41.4%) had diploid DNA distribution patterns. There was a significant difference in 5-year disease-free survival rates between patients with aneuploid and diploid tumors. The difference in cervical metastatic rates between aneuploid and diploid group approximated statistical significance. No obvious correlation was observed between DNA indices and histologic grade, clinical stage or tumor size. It is concluded that patients with aneuploidy primary tumors have a significantly poorer prognosis and higher risk for regional metastases than those with diploid tumors.

Aneuploidy↗
PubMed1989

Expression of Yb1 glutathione S-transferase using a baculovirus expression system.

A full-length cDNA clone was isolated for rat liver Yb1 glutathione S-transferase (EC 2.5.1.18). The coding sequence of Yb1 cDNA was inserted into a baculovirus vector for infection of Spodoptera frugiperda (SF9) cells. The enzymatically active recombinant Yb1 glutathione S-transferase protein has a native molecular weight of 42,000 daltons (by molecular sieve chromatography), a subunit molecular weight of 26,500 daltons (by SDS-polyacrylamide gel electrophoresis), a pI of 8.4 and an extinction coefficient E1%280 of 5.6 +/- 0.4.

Animals↗
PubMed1989

Clinical usefulness of dual-label Schilling test for pancreatic exocrine function.

The usefulness of the pancreatic dual-label Schilling test as an indirect test of pancreatic exocrine function was evaluated. This dual-label Schilling test was based on the difference of absorption for [58Co]cobalamin bound to hog R protein and [57Co]cobalamin bound to intrinsic factor. In this study, the test was performed in 7 normal subjects, 5 patients with pancreatectomy, 12 patients with chronic pancreatitis, 10 patients with suspicion of chronic pancreatitis, and 13 patients without chronic pancreatitis. The normal lower limit (mean -2 SD) of excretion ratio for [58Co]/[57Co] in 24-h urine was 0.68. Of the 26 patients on whom endoscopic retrograde pancreatography was performed, none of the 9 patients with normal pancreatogram, 4 of the 9 patients with mild to moderate pancreatitic changes in pancreatogram, and 7 of the 8 patients with advanced pancreatitic changes in pancreatogram showed a positive value lower than the ratio of 0.68 in this test. In 28 patients examined with the direct test of pancreatic secretory capacity, 2 of the 13 patients with normal function, 6 of the 9 patients with mild dysfunction, and 5 of the 6 patients with definite dysfunction were positive in this test. The results of the pancreatic dual-label Schilling test significantly correlated with those of a direct test of pancreatic secretory capacity and the findings of pancreatitic changes in pancreatogram (p less than 0.01, chi 2 test). The ratio for [58Co]/[57Co] correlated (r = 0.73) with the maximal bicarbonate concentration in duodenal juice of the direct test of pancreatic secretory capacity. The impairment of bicarbonate output by the pancreas may adversely affect the transfer of cobalamin from R protein to intrinsic factor. It suggested that the pancreatic dual-label Schilling test is useful for detecting not only patients with severe pancreatic insufficiency but also the relatively early stage of chronic pancreatitis with bicarbonate secretory dysfunction of the pancreas.

4-Aminobenzoic Acid↗
PubMed1989

[An electron microscopic study on the ultrastructure and enzyme cytochemistry of Pseudomonas putrefaciens].

In this paper, PTA staining, ultrathin sectioning and electron microscopic enzyme cytochemistry techniques were used to study the ultrastructure, as well as reactivity and localization of catalase and peroxidase in Ps. putrefaciens. Its ultrastructure is similar to that of other gram-negative bacilli. Catalase is distributed in the cytoplasm, while peroxidase localized at cytoplasmic membrane and mesosomes.

Catalase↗
PubMed1988

Immunologic and clinical studies on murine experimental autoimmune gastritis induced by neonatal thymectomy.

Experimental autoimmune gastritis (AIG), defined by the appearance of auto antibodies to parietal cells, was induced by neonatal thymectomy in BALB/c nu/+mice 3 days after birth. Vitamin B12 absorption and intrinsic factor in the stomach extract decreased compared with those in AIG-negative control groups. No decrease of the serum A/G ratio in AIG-bearing mice was observed. Although development of anemia, as evaluated by a decrease in hematocrit value, was poor until 12 mo of age and the gastric mucosa was hypertrophic, the AIG resembled human pernicious anemia rather than Ménétrier's disease. Adoptive transfer of spleen cells, but not sera, of AIG-bearing nu/+ into BALB/c nu/nu mice caused AIG in all animals 1 mo later, indicating the involvement of lymphocytes in the induction mechanism of AIG. Cytofluorometric and immunohistochemical analysis of lymphocytes in the gastric mucosa revealed T-cell infiltration at an early stage (1.5-3 mo) followed by B cell infiltration (6 mo). When the fraction enriched with parietal cells, which were intensively stained with sera of AIG-bearing mice and fluorescent antibody to mouse immunoglobulin G, was injected into the foot pads of AIG-bearing nude mice, typical delayed-type hypersensitivity reaction was observed in all animals. This was not seen in the mice injected with the cell fraction enriched with chief cells, although a few of them were stained by the immunofluorescent technique. Thus, the delayed-type hypersensitivity reaction seems to be directly involved in the mechanism of tissue damage.

Anemia, Pernicious↗
PubMed1987

The absorption of free vitamin B12 and R protein-bound vitamin B12 in the diagnosis of pancreatic exocrine insufficiency in rats.

Vitamin B12 (B12) absorption was studied in rats following biliopancreatic duct ligation. The absorption of free B12, as well as of hog R protein-bound B12, was markedly impaired after both intragastric and intraduodenal administration in these rats. The intraduodenal administration of a mixture of pancreatic extract and sodium bicarbonate (NaHCO3) improved the absorption of both free and R protein-bound B12. However, pancreatic extract without NaHCO3 was ineffective in this respect. Intraduodenal administration of NaHCO3 without pancreatic extract worsened the R protein-bound B12 absorption. This finding would indicate that the degradation of R protein by proteolytic enzymes, in the intestine of rats with pancreatic juice exclusion, is inhibited by NaHCO3.

Animals↗
PubMed1987

Demonstration of persistent left superior vena cava by first pass radionuclide angiography.

A case of the left superior vena cava draining to the coronary sinus without associated intracardiac shunt was initially demonstrated by first pass radionuclide angiography. The patient had atypical chest pain for 8 years, and had sick sinus syndrome with a long cardiac pause. Cardiac catheterization confirmed this diagnosis, and a transvenous pacemaker was successfully implanted through the left superior vena cava.

Aged↗
PubMed1987

Demonstration of intracardiac tumor and its associated hemodynamic derangement by radionuclide angiography.

A case of malignant lymphoma primarily involving the heart is reported for the first time in which the tumor per se and its accompanying hemodynamic abnormalities were demonstrated by radionuclide angiography (RNA). The patient had severe and progressive failure of the right side of the heart of obscure origin. The tumor was pathologically proven to have involvement of the pericardium, right atrium, and right ventricle, causing significant tricuspid and pulmonic obstruction.

Heart Failure↗
PubMed1987

In vivo localisation of human urinary bladder carcinoma xenograft in nude mice using radiolabelled monoclonal antibody.

Monoclonal antibody 1G3.10 (mouse IgG3) against the human urinary bladder carcinoma TSGH-8301 was isolated from hybridoma ascites and labelled with radioiodine. The antibody reacts with a cell surface antigen preferentially expressed in human bladder carcinoma. Binding studies in vitro demonstrated that its specificity for antigen was retained after iodination. The clearance of the radiolabelled monoclonal antibody was not modified by the presence of the tumour. In vivo localisation of the radiolabelled antibody and control normal IgG to tumour xenograft was determined by counting the tissue radioactivity and by external gamma ray scintigraphy with computer analysis of the region of interest at various times after the intravenous injection of radiolabelled antibodies. Maximum tumour-to-blood radioactivity (4.5) was obtained 4 days after antibody injection. There was no tumour localisation of radiolabelled normal IgG. Specificity of the localisation was also confirmed by using a non-reactive colon carcinoma xenograft. Distinct tumour images were obtained without the use of subtraction techniques. These studies of human bladder tumour localisation using this monoclonal antibody show its obvious potential for clinical use.

Animals↗
PubMed1985

Evaluation of a new assay kit for intrinsic factor blocking antibody (type I) as an aid in the diagnosis of pernicious anemia.

Sera from 39 patients with pernicious anemia and 251 patients with various other diseases and 42 healthy normal subjects were tested for intrinsic factor blocking antibody by a Corning commercial kit. Twenty-five (64%) out of 39 pernicious anemia patients showed a positive reaction to the intrinsic factor blocking antibody. The positive incidence of intrinsic factor blocking antibody by this method agreed well with the results obtained in this laboratory over the past 10 years using the charcoal method. No sera from normal subjects tested were positive for the intrinsic factor blocking antibody. All 226 sera with vitamin B12 levels less than 3,500 pg/ml which came from patients without pernicious anemia, were negative for the intrinsic factor blocking antibody. In 15 sera with B12 levels greater than 3,500 pg/ml from patients who received recent B12 medications, 11 sera showed false positive results. On the other hand, no false positive results were obtained by this method in 10 sera with endogenous serum B12 levels greater than 3,500 pg/ml collected from patients with chronic myelogenous leukemia. It is reasonable to presume that this assay is clinically useful for detection of intrinsic factor blocking antibody in the diagnosis of pernicious anemia, if false positive results due to B12 medication are excluded.

Adolescent↗