Transfer RNA: change of conformation upon aminoacylation determined by Raman spectroscopy.
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Amino Acyl-tRNA Synthetases↗
Biomedical subjects
M C Chen
Publications and source records attributed to M C Chen.
Poly(inosinic acid)-poly(cytidylic acid) inhibition of DNA synthesis in synchronized HeLa cells.
Inhibition by double-stranded polyribonucleotides of DNA synthesis in synchronized HeLa cultures is dose- and time-dependent. Inhibition by poly(I.C) primarily affected late G(1) and early S phases of the cell cycle. Single-stranded polynucleotides, native calf-thymus DNA, and yeast RNA had no effect. Radioautography showed that after 2-hr exposure the synthetic polyribonucleotides were predominantly inside the nucleus. The results extend the spectrum of action of double-stranded RNA.
Autoradiography↗
Hepatic metastases: rat models for imaging research.
Improved rat liver tumor models with solitary or multiple metastatic tumors were developed for radiological imaging research. Unlike previous studies which employed trocar inoculation of tumor fragments, an enzymatically disaggregated cell suspension of mammary cancer was injected by fine needle either directly into the liver to produce solitary cancer nodules, or indirectly via the spleen or mesenteric vein to produce multiple liver metastases. Tumor size was proportional to the time elapsed after implantation. The operative mortality of direct liver, splenic parenchymal, and mesenteric inoculations were 8%, 4%, and 27%, respectively. MR tissue characteristics, image contrast, and pharmaceutical enhancement of these tumors closely resembles human hepatic metastases. The availability of reproducible, inexpensive animal models of metastatic cancer allows efficient evaluation of new liver imaging techniques.
Adenocarcinoma↗
Preferred T-cell receptor V beta usage in the xenogeneic human antiporcine cytolytic response.
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Animals↗
Biliary manometry versus clinical trial: value as predictors of success after treatment of biliary tract strictures.
PURPOSE: To evaluate the biliary manometric-perfusion test (BMPT) and clinical trial as predictors of long-term success after percutaneous and surgical treatment of biliary tract strictures. PATIENTS AND METHODS: After percutaneous intervention or surgical repair of extrahepatic bile duct strictures, 43 patients underwent long-term biliary intubation (mean, 13 months) with 61 internal-external stents. Before removal of the stents, all 43 patients underwent a BMPT (n = 65) and 24 underwent a 2-3-week clinical trial (n = 27) with stents positioned above the treated region. Patients were followed up 1-46 months (mean, 16 months) after stent removal, with clinical outcome determined by means of physical examination, biochemical evaluation, chart review, and telephone interview. RESULTS: With logistic regression analysis, the BMPT and clinical trial were shown to have equal predictive value in determining treatment success or failure. Eighty-four percent of the clinical outcomes were correctly predicted with BMPT, versus 88% for the clinical trial. Kaplan-Meier survival curve analysis demonstrated the probability of remaining stricture free at 1 year after passing a BMPT and after passing a clinical trial to be 90% and 86% (P = .55), respectively. CONCLUSION: BMPT and clinical trial have similar capabilities in the prediction of long-term patency after treatment of benign biliary tract strictures, but the BMPT is less costly and time consuming for the patient.
Anastomosis, Roux-en-Y↗
Anomalous systemic arterialization to normal basal segments of the left lower lobe: helical CT and CTA findings.
PURPOSE: The purpose of this work was to evaluate the helical CT and CT angiography (CTA) findings of anomalous systemic artery (ASA) to the basal segments of the left lower lobe (LLL). METHOD: Three patients (two had hemoptysis, one was asymptomatic) with blotchy nodular density in the LLL revealed on chest radiographs underwent helical CT and CTA. Bronchoscopy was performed in two of these patients. Angiography and surgery were performed in one patient. RESULTS: All three patients demonstrated characteristic helical CT and CTA findings including 1) a sigmoid-shaped ASA originating from the lower descending thoracic aorta, with a distal bulbous configuration and four arterial branches supplying the basal segments of the LLL; 2) absence of an interlobar pulmonary artery or presence of a small artery lateral to the truncus basalis; 3) engorged vascular markings in the basal segments of the LLL; and 4) normal tracheobronchial tree and lung parenchyma. CONCLUSION: The findings in the present three cases suggest that the use of invasive studies such as angiography or bronchoscopy may be obviated in the diagnosis of ASA to the LLL because diagnosis can be provided through a clear set of criteria on helical CT and CTA.
Adult↗
Mesenteric vein thrombosis. Four cases and review of the literature.
Mesenteric vein thrombosis, an uncommon but important clinical entity, can cause ischemia or infarction of the small intestine. Mesenteric vein thrombosis was first described nearly a century ago, but diagnosis remains difficult because it can affect young individuals without any known predisposing disorder and because patients often present with nonspecific abdominal symptoms. We report 4 cases of small intestinal ischemia secondary to superior mesenteric vein thrombosis. Three were due to hypercoagulable states (protein-S deficiency, factor-VII abnormalities) and one was idiopathic. In recent years, the development of modern imaging techniques (particularly ultrasonography, duplex scanning, and computed tomography) have enabled early recognition of this disease. Anticoagulation is therapeutic acutely unless there are signs of peritonitis which necessitate surgical resection of the infarcted bowel.
Adult↗
Paroxysmal atrial tachycardia with second-degree atrioventricular block.
Paroxysmal atrial tachycardia with atrioventricular block usually indicates potentially dangerous overdigitalization, and serious heart disease is almost universally present. In this report, we describe a patient with a structurally normal heart who manifested spontaneously intra-atrial reentrant tachycardia with Wenckebach atrioventricular block in the absence of medications. In this patient, the longest atrial paced cycle length that induced atrioventricular nodal block was 390 ms, and the atrial cycle length during tachycardia ranged from 360 to 400 ms. The electrophysiologic study in our patient demonstrated that second-degree atrioventricular block during atrial tachycardia may occur in patients without structural heart diseases or taking any medication.
Electrocardiography↗
Regulation of histamine release from oxyntic mucosa.
The regulation of histamine release from oxyntic mucosa is complex because of two potential sources of histamine: mast cells and enterochromaffin-like (ECL) cells. A gastrin-responsive histamine pool was identified in the rat oxyntic mucosa two decades ago, but these ECL cells from the rat have not yet been isolated or characterized in vitro. In vivo studies in canine and human mucosa have been more difficult because of the high content of histamine in mast cells. Using enzyme-dispersed canine oxyntic mucosal cells, we have studied regulation of histamine release from a mast cell-depleted fraction prepared by sequential elutriation and density gradient. Histamine-like immunoreactivity was demonstrated, using peroxidase-anti-peroxidase immunohistochemistry. After short-term culture, histamine was released in response to gastrin, cholecystokinin, carbachol, and forskolin. Somatostatin potently and effectively inhibited the response to gastrin. The cultures used for these studies also contained somatostatin cells, and, furthermore, the response to gastrin was enhanced by incubation with monoclonal antibodies to somatostatin. The latter findings suggested that somatostatin was acting in these cultures by a paracrine route. This pattern contrasts with that obtained in previous studies of canine oxyntic mucosal mast cells.
Animals↗
Serum cholesterol level and hepatoma.
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Adult↗
The pathways regulating acid secretion: the view from the isolated cell.
Although many aspects of the regulation of acid secretion at the cellular level among different species remains controversial, certain concepts have emerged that span the differences between species, model systems and investigators. The paracrine, endocrine, neural and autocrine pathways mediate acid secretion by acting both directly on the parietal cell and indirectly via modulation of mucosal paracrine cell function. Studies with cells isolated from the acid secreting canine oxyntic mucosa indicate that gastrin and cholinergic receptors are present on parietal cells, somatostatin cells, and the histamine-enterochromaffin-like cell (ECL). Subtypes of these receptors are clearly important; the gastrin receptor on the ECL cell and parietal cell are "B" type CCK/gastrin receptors, whereas the receptor on the somatostatin cell is an A type CCK receptor. From the vantage point of studies in the canine oxyntic mucosa, the challenge is no longer to determine whether parietal, histamine or somatostatin cells have gastrin or muscarinic receptors but to establish the physiologic relevance of the specific actions (secretory, trophic or differentiative) of these receptor subtypes. Furthermore, the mechanisms integrating these paracrine, exocrine and neural elements require elucidation.
Animals↗
Breast-feeding counseling by a 24-hour telephone hot-line.
A 24-hour telephone hot-line functioning as a counseling service and case registry was included in a multi-faceted breast-feeding promotion program. The mothers could speak directly to especially trained staff members in a municipal hospital. All the questions were answered according to an "Answering Book" which included the anticipated question and the optimum answer. A total of 201 calls, which included 340 problems, were recorded from January 1, 1993 to October 31, 1993. Almost all the calls were made by the mothers (99%), and more than half (57.7%) of the mothers were primiparous. Most of the calls (79.6%) were made between 8 AM to 4 PM. The questions were frequently raised when the baby was aged 8 to 14 days (23.4%). The most frequently asked questions were: (1) insufficient milk? (14.1%), (2) frequent and loose stools? (13.2%), (3) weaning? (10.3%), (4) drugs? (6.8%), (5) additional formula or water? (6.2%), and (6) maternal contraindication? (6.2%). Although the impact of this telephone consultation could not be properly evaluated, the incidence of breast-feeding during hospital stay increased from 50% to 73.4%, and breast-feeding for more than 1 month increased from 22.7% to 42.2% before and after the whole promotion program. It is recommended that health care professionals provide more help when the mother leaves the hospital. A nation-wide toll-free telephone operated by the Department of Health to increase the chance of successful breast-feeding is also recommended.
Breast Feeding↗
Ultrasonic dissection in resection of hepatocellular carcinoma.
An ultrasonic dissector has been used in the resection of liver tumors and was found to be safe and efficient in noncirrhotic patients. Thirty-one (cirrhosis, 61%) liver resections for hepatoma treated with ultrasonic dissector were compared to 39 (cirrhosis, 74%) resections treated with finger fracture. We found that patients treated with an ultrasonic dissector versus those treated by finger fracture, had less blood loss (especially in cirrhotic liver), 836 +/- 593 cc vs 1348 +/- 1226 cc, more operative time, 337.6 +/- 100.5 min vs 197 +/- 92.8 min, more days of hospital stay 19.1 +/- 12.8 days vs 11.5 +/- 5.6 days and more days of removal of drains, 14.9 +/- 11.7 days vs 10.2 +/- 6.4 days. The morbidity, mortality, amount of blood transfusion and amount of drainage were quite similar between two groups.
Adult↗
Surgical treatment of cholangiocarcinoma.
BACKGROUND/AIMS: To report the results of surgical treatment of intrahepatic cholangiocarcinoma with different procedures and to find the factors that may affect the long-term survival. MATERIALS AND METHODS: From 1987 to 1994, 57 patients with intrahepatic cholangiocarcinoma underwent laparotomy. Among them, resection was performed in 27 patients, operative drainage in 14 patients and biopsy only in 14 patients. The liver resections included 9 right lobectomies, 14 left lobectomies and 4 hilar resections. All specimens were stained with carcinoembryonic antigen (CEA) and HLA-DR monoclonal antibodies. RESULTS: There were 7 postoperative mortalities, one in the resection group (1/27), two in the drainage group (2/14) and 4 in the biopsy group (4/14). Patients undergoing resection survived significantly longer (median, 8 months) (mean, 19 +/- 4 months) than patients undergoing drainage (median, 4 months) (mean, 6 +/- 2 months) and biopsy (median, 2 months) (mean, 3 +/- 1 months) (p < 0.01). After resection, univariate analysis showed that positive hiliar lymphnode was a poor prognostic sign and mucobilia was a good prognostic sign. Age, sex, size of tumors cell differentiation, clear margin, and positive HLA-DR and CEA had no effect on prognosis. CONCLUSION: The results support the surgical resection of intrahepatic cholangiocarcinoma. Tumor free margin should be aggressively achieved but may not be necessary. Mucobilia is a good prognostic sign and positive hilar lymphnode is a grave sign.
Adult↗
Adenocarcinoma in the middle third of the stomach--an evaluation for the prognostic significance of clinicopathological features.
BACKGROUND/AIMS: The prognosis of patients with gastric adenocarcinoma varies with the location of the tumor. Adenocarcinoma in the middle third of the stomach has been claimed to have a better outcome than those in other locations. However, there is still very limited information specifically regarding the prognostic factors which influence the survival time of patients with adenocarcinoma in the middle third of the stomach. This retrospective study was designed with the aim to evaluate and uncover the possible significant clinicopathological parameters for adenocarcinoma in the middle third of the stomach. METHODOLOGY: Between 1986 and 1992, 363 patients underwent gastric resection for primary gastric adenocarcinoma at this hospital. Fifty-two (14.3%) of these patients were included in this study and they all met the following criteria: 1) tumor primarily located in the middle third of the stomach without distant metastases or peritoneal seeding, 2) undergoing curative resection and 3) undergoing R2 nodal dissection, at least. The clinicopathological findings were obtained by detailed review of the medical records and the histologic slides. All surviving patients were also contacted and their current conditions were recorded. RESULTS: The overall 5-year survival rate (Kaplan-Meier method) was 42.5%. In univariate survival analysis by Kaplan-Meier method and long-rank test, serosal invasion (p < 0.01), lymph node metastasis (p < 0.01) and lymphatic involvement (p < 0.01) had an individual prognostic significance. When a multivariate analysis using Cox proportional hazards regression was performed, serosal invasion (P < 0.01) and lymphatic involvement (p < 0.05) appeared as the only two independent prognostic factors regarding long-term survival. When these 52 patients were categorized into patients with early gastric cancer (n = 10) and patients with advanced gastric cancer (n = 42), there was a significant difference (p < 0.01) between the survival rates (90.0% vs. 29.1%). When these tumors were further categorized into early gastric cancer (n = 10), early simulating advanced gastric cancer (n = 14) and Borrmann type advanced gastric cancer (n = 28), there were significant differences (P < 0.01 and P < 0.01, respectively) in 5-year overall survival rates between early gastric cancer (90.0%) and Borrmann type advanced gastric cancer (18.9%), also between early simulating advanced gastric cancer (52.5%) and Borrmann type advanced gastric cancer (18.9%). UICC stage also had significant influence (P < 0.01) on the survival rates. CONCLUSIONS: Serosal invasion and lymphatic involvement are the significant, independent prognostic factors in predicting the survival rate of patients with adenocarcinoma in the middle third of the stomach. Since more advanced stage tumors usually carry a poorer prognosis, early detection is of extreme importance for improving the survival rate.
Adenocarcinoma↗