Biomedical subjects

K W Chen

Publications and source records attributed to K W Chen.

At least 55 records · Page 3Linked to original sources

PubMed1995

Severe hepatocellular damage induced by chlormezanone overdose.

Chlormezanone is a widely prescribed muscle relaxant (1-3) whose pharmacology is well known (4-6), but the clinical effect of overdose still remains relatively obscure (1, 7, 8). We here report a recent case of a patient who had severe liver function impairment and other associated findings typical of chlormezanone overdose. The ingested dose (at least 12 g) is much larger than those of previous record (1, 2, 7, 8); thus, her critical presentation deserves to be reviewed.

Adult↗

PubMed1995

Gas composition in Clostridium septicum gas gangrene.

Clostridial gas gangrene (myonecrosis) is a rare but catastrophic condition that usually occurs in patients with underlying diseases. This paper reports a fatal case of spontaneous clostridial gas gangrene in a 60-year-old female diabetic patient. The composition of gas samples from the patient's damaged muscle was analyzed. The results showed 5.9% hydrogen, 3.4% carbon dioxide, 74.5% nitrogen and 16.1% oxygen. This gas composition supports the belief that such gas production occurs via glucose fermentation. This is the first time such an analysis has been performed in a clinical case of spontaneous clostridial gas gangrene.

Clostridium↗

PubMed1994

Recurrent emphysematous pyelonephritis. A case report.

Emphysematous pyelonephritis (EPN) is an uncommon but necrotizing renal infection due to gas-forming coliform bacteria that usually occurs in patients with diabetes mellitus and/or obstructive uropathy. Bilateral EPN is rarely seen and recurrent infection in different kidneys has never been reported in the literature. Here we present a female diabetic patient who experienced two episodes of EPN in different kidneys within 2.5 years, resulting in death eventually. We discuss the pathogenesis, incompatibility between clinical features and radiological findings of EPN, and the principle of management for this life-threatening infection.

Diabetic Nephropathies↗

PubMed1994

Gas in hepatic veins: a rare and critical presentation of emphysematous pyelonephritis.

Although emphysematous pyelonephritis has been recognized for more than a hundred years, the actual etiology is still unknown. Glucose fermentation has been implicated as a mechanism of gas formation. We report a case of emphysematous pyelonephritis in which real-time ultrasonography demonstrated intravascular gas bubbles originating in the involved kidney, and passing into the inferior vena cava and hepatic veins. Gas from the affected kidney was analyzed by chromatography; the result showed hydrogen 10.5%, carbon dioxide 39%, nitrogen 49.6% and oxygen 0.8%. The clinical presentation and the results of gas analysis implicate a critical condition that bacteria proliferated rapidly by mixed acid fermentation of glucose. Additionally, the finding of gas production and transportation could explain the previous hypothesis of gas transport. In this critical situation immediate drainage with medical intervention is indicated to treat this life threatening condition.

Adult↗

PubMed1994

Bilateral spontaneous pneumothoraces, pneumopericardium, pneumomediastinum, and subcutaneous emphysema: a rare presentation of paraquat intoxication.

Pneumothorax, subcutaneous emphysema, and pneumomediastinum occur frequently in critically ill patients in association with blunt or penetrating injuries or other conditions while performing Valsalva-like maneuvers. We present the case of a patient with bilateral pneumothoraces, pneumomediastinum, pneumopericardium, and subcutaneous emphysema after acute paraquat intoxication.

Acute Disease↗

PubMed1994

Bleeding peptic ulcer--risk factors for rebleeding and sequential changes in endoscopic findings.

From September 1991 to December 1992, a prospective study was conducted to determine the risk factors and residual risk of rebleeding, and the evolutionary endoscopic changes in peptic ulcers that rebled. Emergency endoscopies were performed on 452 patients with haematemesis or a melaena, or both within 24 hours of admission. If the lesions were actively bleeding, then the patients were treated with injection sclerotherapy. A multivariate analysis of clinical, laboratory, and endoscopic variables of 204 patients with ulcer bleeding showed that hypovolaemic shock, a non-bleeding visible vessel, and an adherent clot on the ulcer base were independently significant in predicting rebleeding (p < 0.05). Considering these three factors according to the estimates of their regression coefficients showed that a non-bleeding visible vessel was the strongest predictor of rebleeding. The study of the residual risk of rebleeding after admission showed that most rebleeding episodes (94.1%), including all associated with hypovolaemic shock, surgical treatment, and death, occurred within 96 hours of admission. After this time, the residual risk of rebleeding was less than 1%. Study of the changes in endoscopic findings before and after rebleeding illustrated that all ulcers with a visible vessel or adherent clot showed at follow up endoscopy were derived from ulcers with initial major stigmata. It is concluded that hypovolaemic shock, a non-bleeding visible vessel, and an adherent clot on an ulcer base are of independent significance in predicting rebleeding. Observation for 96 hours is sufficient to detect most rebleeding episodes after an initial bleed from peptic ulcer.

Blood Vessels↗

PubMed1994

Active, bleeding marginal ulcer of Billroth II gastric resection: a clinical experience of 18 patients.

OBJECTIVES: From July 1988 to April 1993, 18 patients with active, marginal ulcer bleeding were investigated for their clinical presentation, endoscopic findings, and successful rate of therapeutic endoscopy. METHODS: Through endoscopic survey, data on the ulcer number, ulcer location, and prevalence rate of each major stigmata of recent hemorrhage were obtained. Therapeutic methods used include heater probe thermocoagulation and local injection with diluted epinephrine (0.01%) or 95% alcohol through the endoscope. RESULTS: All patients were male with a mean age of 65.3 years. Tarry stool passage (15/18; 83.3%) was the most common clinical presentation. Fifteen patients (15/18; 83.3%) had single marginal ulcer. Ulcerations were located in the jejunal site (12/18; 66.6%) and gastro-jejunal anastomosis (5/18; 27.7%). There were two patients with spurting artery, six with nonbleeding visible vessel, two with blood clot adhesion, four with oozing, three with visible vessel-associated oozing and three, with blood clot adhesion accompanying oozing. The rate of therapeutic endoscopy to successfully stop bleeding or prevent rebleeding was 94.4% (17/18). Sixteen cases (16/17) received one session of endoscopic therapy, and one patient (1/17) accepted two sessions. One patient with multiple underlying diseases died of persistent bleeding after three sessions of therapy. No complication was found to be related to the endoscopic procedure. CONCLUSIONS: Marginal ulcer bleeding exhibits the same endoscopic findings as peptic ulcer hemorrhage. Most marginal ulcers are single and located at the saddle area of the jejunal site. Endoscopy can be useful in diagnosing marginal ulcer, and it is safe and effective in managing active marginal ulcer bleeding.

Aged↗

PubMed1994

Endoscopic removal of a large intragastric foreign body with an overtube: a case report.

After amphetamine ingestion, a 39-year-old male attempted suicide by swallowing glass trifles, cigarette lighter and razor blades. All foreign bodies ingested were evacuated spontaneously and smoothly within one week, except for the 10-cm long lighter, which was removed by endoscopy via supplementary overtube with moderate difficulty. The subsequent clinical course was uncomplicated. More than 80% of the ingested foreign bodies which reach the stomach can be eliminated uneventfully through the gastrointestinal tract. The remainder may cause complications such as obstruction, perforation and hemorrhage. Usually the locations of obstruction are over the three anatomic narrowings of the esophagus, the pyloric ring and ileocecal valve. Perforation occurs with ingestion of long, sharp, metallic pointed objects or animal bones, and is more frequent among those who had previous abdominal surgery or intestinal diseases. Endoscopic removal as soon as possible is suggested for high risk groups, with use of the overtube method to prevent complications.

Adult↗

PubMed1993

Effect of gliclazide on plasma lipids and pancreatic beta cell function in non-insulin-dependent diabetes mellitus.

Eighteen patients with non-insulin-dependent diabetes mellitus (NIDDM), who were newly diagnosed or had their oral hypoglycemic agents discontinued for more than 3 months, were studied to evaluate the effect of gliclazide on glycemic control, plasma lipids and beta cell function. The mean fasting plasma glucose (249 +/- 11 vs 170 +/- 10 mg/dl, p < 0.001), postprandial plasma glucose (353 +/- 16 vs 237 +/- 16 mg/dl, p < 0.001) and HbA1C (9.6 +/- 0.4 vs 6.5 +/- 0.3% p < 0.001) decreased significantly after 3-months of gliclazide treatment. The beta cell function showed a significant increase in fasting serum C-peptide (1.8 +/- 0.2 vs 2.1 +/- 0.3 ng/ml, p < 0.05) and an insignificant increment in serum C-peptide after glucagon stimulation (2.2 +/- 0.3 vs 2.2 +/- 0.4 ng/ml, p < 0.1). In 8 cases with an initial serum cholesterol above 200 mg/dl, the serum cholesterol decreased significantly (236 +/- 8 vs 200 +/- 12 mg/dl, p < 0.05). However, LDL-cholesterol (164 +/- 8 vs 145 +/- 13 mg, p > 0.05) and HDL-cholesterol (66 +/- 5 vs 54 +/- 9 mg, p > 0.05) showed insignificant decrease after gliclazide therapy. In 4 patients with hypertriglyceridemia, the serum triglyceride decreased (441 +/- 161 vs 239 +/- 73 mg/dl, p > 0.1), but this was not statistically significant. These findings suggest that hyperglycemia, fasting serum C-peptide levels and hypercholesteremia are significantly improved after a 3-month period of gliclazide therapy in NIDDM patients.

Adult↗

PubMed1992

Studies of a tumor-associated antigen, COX-1, recognized by a monoclonal antibody.

Monoclonal antibodies against an ovarian tumor cell line, OC-3-VGH, were generated using modified hybridoma technology. Among the seven that were selected for their high specificity and affinity to ovarian cancer cells and low cross-reactivity to most normal human tissues, RP 215 was shown to react specifically with a tumor-associated antigen, COX-1, from certain ovarian/cervical cancer cell lines. By Western blot assay, COX-1 was shown to have a subunit molecular mass of about 60 kDa and exist as an aggregate in the native state. COX-1 could also be detected in the shed medium of certain cultured tumor cells. A solid-phase sandwich enzyme-immunoassay procedure was designed for quantitative determinations of COX-1 in the shed medium or in patients' sera using RP 215 for both well-coating and the signal detection. Highly purified COX-1 was obtained from the shed medium of cultured OC-3-VGH tumor cells mainly by hydroxyapatite and immunoaffinity chromatography with RP 215 as the affinity ligand. At neutral pH, purified COX-1 also exists as an aggregate and is relatively stable at temperatures below 50 degrees C. Its immunoactivity was found to decrease with time in the presence of trypsin. However, the immunoactivity of COX-1 was not affected upon incubation with carbohydrate-digestive enzymes or concanavalin A and only partially inactivated in the presence of NaIO4 or iodoacetamide. Treatments of COX-1 with dithiothreitol and guanidine thiocyanate resulted in a complete loss of activity. Furthermore, rabbit antisera raised against purified COX-1 exhibited similar immunospecificity to that of RP 215. The results of this study suggest that COX-1 is a glycoprotein consisting of a 60 kDa subunit, which is recognized by RP 215 through its peptide determinant. Preliminary retrospective clinical studies were performed to assess the utility of a COX-1 enzyme immunoassay kit for detection and monitoring of patients with ovarian and cervical cancers.

Antibodies, Monoclonal↗

PubMed1992

Acute bacterial nephritis: a clinicoradiologic correlation based on computed tomography.

PURPOSE: Acute bacterial nephritis (ABN) represents localized, nonliquefied renal infection, and the subsequent alteration of tissue densities can be readily detected by computed tomography (CT). In recent literature, a variety of renal parenchymal alterations observed on CT were reported. However, previous reports on the clinical course of ABN were inconsistent and lacked correlation with radiologic findings. In this investigation, we attempt to correlate the severity of clinical manifestations with CT findings in ABN and draw some conclusions regarding the natural history, pathophysiology, and clinical management of this disease. PATIENTS AND METHODS: From July 1988 to June 1991, 30 cases of ABN were evaluated at our institute. On the basis of postcontrast-enhanced CT findings, 28 cases were grouped into (1) Group I (7 cases), wedge-shaped lesions (focal or diffuse); (2) Group II (12 cases), focal mass-like lesions; and (3) Group III (9 cases), diffuse (multifocal) mass-like lesions. The clinical features and outcomes of the three groups were compared. The positive detecting rates and clinical usefulness of ultrasonographic (US) and urographic examinations were also studied in each group. RESULTS: An excellent correlation can be demonstrated between the clinical parameters (including underlying diseases, maximum temperature and leukocyte count, duration of fever, flank pain, leukocytosis, and pyuria; the incidence of septic shock, diabetic ketoacidosis, and acute renal failure; and outcome) and the pattern of renal parenchymal abnormalities detected on CT. The clinical features in Group I patients displayed many similarities with those in uncomplicated acute pyelonephritis (APN) reported previously, and responded to antibiotic therapy promptly. Most patients in Group II were successfully treated with antibiotics but had a protracted clinical course with a slower clinical improvement than Group I. Only one case with a Group II lesion was noted to progress to renal abscess formation and extrarenal involvement. In comparison, 33% of the patients in Group III died despite antibiotic therapy. Our data also show that US examination is sensitive in detecting Group II ABN lesions (62% positive rate), and revealed marked renal enlargement in most Group III lesions (89%). It is therefore a useful initial imaging modality in providing information vital to clinical decision making. CONCLUSION: Our experiences suggest that renal bacterial infection may show the continuum of severity from uncomplicated APN to ABN, demonstrated on postcontrast CT scan as wedge-shaped lesions to mass-like lesions, and possibly, finally to frank abscess formation. We classify ABN into three subgroups according to CT findings, and good correlation with clinical severity is demonstrated. These findings deliver valuable concepts regarding the pathophysiology and clinical management of this disease.

Acute Disease↗

PubMed1992

Enzyme immunoassay for prostate-specific antigen and its diagnostic application in prostate cancer.

The purpose of this study was to develop a reliable screening test for prostate cancer. Monoclonal antibodies specific to the prostate-specific antigen (PSA) were generated with an improved hybridoma technique. The hybrid cells were initially cultured in a semisolid medium containing methylcellulose and later transferred to a liquid medium for further subculture. Thirty-six out of a total 1,250 recovered colonies were shown to exhibit a high affinity to PSA by radioimmunobinding assay. Eight hybrid cell lines which secreted either IgG1 or IgG2a antibodies of a high affinity and specificity were established for evaluation. The association constants between PSA and these monoclonal antibodies were shown to range from 1 x 10(9) to 5 x 10(9) M-1. From the results of a matrix cross-matching procedure, pairs of monoclonal antibodies were identified and the corresponding epitopes assigned, and most of them could also be paired with rabbit anti-PSA in a typical sandwich enzyme immunoassay. The designated EIA procedure was performed over 90 minutes at room temperature in a two-stage incubation protocol with a sensitivity of 0.4 ng/mL. The EIA kit was shown to have little cross-reactivity with thyroid stimulating hormone, alpha-fetoprotein, carcinoembryonic antigen and prostate acid phosphatase. Preliminary evaluations with clinically defined patients' sera revealed that proper selections of antibody pairs in sandwich immunoassays are crucial to the adequate performance of the EIA kits.

Antibodies, Monoclonal↗

PubMed1992

Binding and growth-stimulation of cervical cancer cell lines by prolactin.

Two cervical cancer cell lines CC7-T and Si-Ha were employed to observe the relationship between cervical cancer and prolactin. By immunocytochemical and indirect immunofluorescent assays using two prolactin monoclonal antibodies PRL-149 and PRL-151, both cell lines with added prolactin (10 ng/mL) were noted to be positive for PRL-151, but negative for PRL-149. The control cell lines from ovarian cancer and the myeloma lines were both stained negative. By using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, it was noted that CC7-T and Si-Ha grew better in the presence of various added concentrations of prolactin, ranging from 0.1 to 1,000 ng/mL, suggesting that prolactin may enhance the growth of cervical cancer. The degree of stimulation appears to depend on cell differentiation. However, prolactin levels in the cultured supernatant were undetectable by the enzyme immunoassay (EIA) method. We postulate that prolactin can bind and stimulate the growth of some cervical cancer cell lines, probably through the prolactin receptor rather than by autocrine regulation.

Animals↗

PubMed1991

Mixed acid fermentation of glucose as a mechanism of emphysematous urinary tract infection.

Emphysematous pyelonephritis is a severe necrotizing infection that usually occurs in patients with diabetes mellitus or obstructive uropathy. Although glucose fermentation has been considered as the main cause of gas production the actual mechanism remains controversial. Compositions of gas samples from 2 patients with emphysematous pyelonephritis recently encountered were analyzed, and showed 15% hydrogen, 4.8% carbon dioxide, 60% nitrogen, 6.7% oxygen and some unknown gases in case 1, and 3.4% hydrogen, 22% carbon dioxide, 66% nitrogen and 9.8% oxygen in case 2. These results tend to implicate mixed acid fermentation of glucose as the pathway by which emphysematous urinary tract infections develop.

Aged↗

PubMed1991

The effects of measurement errors in the plasma radioactivity curve on parameter estimation in positron emission tomography.

The effects of three error sources in plasma curve measurements on parameter estimation in kinetic analysis of positron emission tomography (PET) fluorodeoxyglucose (FDG) data are investigated by computer simulation. The three error sources are: (1) measurement noise in the radioactivity concentrations of plasma samples; (2) linear interpolation between adjacent plasma sampling points of the plasma time activity curve; and (3) incorrect weights used for the least-squares regression. All three error sources are found to increase the variability of the parameter estimates, with the first one a primary error source in normal PET FDG studies. The performance of five estimation methods which account for the error sources are evaluated. When the noise variances of the plasma and the tissue measurements are not known, an iterative weighting procedure is shown to give accurate and reliable estimates.

Computer Simulation↗

PubMed1989

Applications of monoclonal antibodies to human follicle-stimulating hormone in enzyme immunoassays.

Monoclonal antibodies against human follicle-stimulating hormone (hFSH) were generated by using an improved hybridoma technique with a semisolid medium in methylcellulose for initial cloning. The generated monoclonal antibodies were characterized with respect to their subunit and epitope specificity as well as cross-reactivity to other glycoprotein hormones. Monoclonal antibodies of high affinity and high specificity to hFSH were finally selected for applications in sandwich enzyme immunoassay. The monoclonal antibody specific to the alpha-subunit of FSH was coated on microtiter wells and served as the first antibody. The other high-affinity monoclonal antibody specific to beta-subunit of FSH was labeled with horseradish peroxidase and served as the second antibody. This immunoassay can be performed within 70 min at room temperature and has a minimum sensitivity of 2 mIU/ml for serum sample.

Animals↗

PubMed1989

Generation of monoclonal antibodies to prostatic acid phosphatase isoenzyme 2 and application in solid-phase enzyme immunoassay.

Monoclonal antibodies specific to prostatic acid phosphatase (PAP) isoenzyme 2 were generated by using an improved hybridoma technique. After three subcutaneous immunizations and three intravenous boosters, cell fusion experiments were performed. The hybrid cells were first cultured in a semisolid medium containing methylcellulose and later transferred to a liquid medium for further subculture. Out of a total of 600 colonies recovered after two cell fusion experiments, 13 were shown to exhibit affinity to PAP isoenzyme 2 by radioimmunoassay. Nine hybrid cell lines which showed high affinity and specificity were established for further evaluation. Their immunoglobulin subclass was determined to be immunoglobulin G. The association constants between PAP isoenzyme 2 and each monoclonal antibody were determined by titration curve in radioimmunoassay (RIA). Three of them (PAP 1, PAP 03, and PAP 019) were shown to be over 1 X 10(9) M-1. From the results of a matrix cross-matching procedure, a pair of antibodies (PAP 03 and PAP 1) reacting with discrete antigenic determinants were identified for preparing a solid phase sandwich enzyme immunoassay (EIA) kit. The designed EIA procedure could be performed within 40 min in a one-stage incubation protocol. The assay time was shorter than that of other commercial RIA or EIA kits, and the sensitivity was 0.4 ng/ml which was comparable to that of RIA kits. The EIA kit was shown not to cross-react with human thyroid stimulating hormone, alpha-fetoprotein, carcinoembryonic antigen, and acid phosphatases derived from tissues other than prostate. Therefore, this design was a simple and rapid method with high sensitivity and specificity for determining PAP isoenzyme 2 in human serum.

Acid Phosphatase↗

PubMed1988

Generation and epitope analysis of thyroid stimulating hormone-specific monoclonal antibodies for enzyme immunoassays.

By using an improved hybridoma technique with a semisolid medium of methylcellulose for initial cloning, numerous high affinity monoclonal antibodies against human thyroid stimulating hormone (TSH) were generated. These antibodies were characterized with respect to their subunit and epitope specificity. Epitope analysis of antibodies specific to the beta-subunit of TSH was performed by a sandwich pairing procedure. Based on the results of this analysis, it was concluded that there are four distinct TSH-specific epitopes on the beta-subunit of TSH; these are designated a, b, c, and ab. The five antibodies binding to epitopes a, b, and c are not mutually exclusive. However, the antibody binding to epitope ab prevents further binding of other antibodies to epitope a or b, but not to epitope c. This epitope analysis enabled us to combine three high affinity monoclonal antibodies, each of which reacts with epitopes a, b, and c, respectively, in a typical sandwich enzyme immunoassay. One was immobilized on polystyrene beads and the other two were conjugated with horseradish peroxidase and served as the second antibodies. This enzyme immunoassay can be performed within 90 min and with a minimum sensitivity of 0.2-0.3 microIU/ml.

Antibodies, Monoclonal↗