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Biomedical subjects

C Chan

Publications and source records attributed to C Chan.

At least 271 records · Page 15Linked to original sources
PubMed1976

Subcellular localization of gamma-glutamyl carboxypeptidase and of folates.

The subcellular distributions of glutamyl carboxypeptidase, folate specific activities, and radioactive metabolites of injected [3H] folic acid were studied in rat liver. The specific activity of glutamyl carboxypeptidase in the lysosomal fraction was near or greater than four times that in the other subcellular fractions. The specific activity of folates was highest in the soluble fraction (102 ng folate/mg protein) and lowest in the microsomal fraction (22 ng folate/mg protein). Nuclear, mitochondrial, and lysosomal folates were 95% folate polyglutamates, and microsomal and soluble folates were 85--90% folate polyglutamates. Injected [3H] folic acid was initially concentrated in the microsomal fraction, as measured by 3h cpm per ng folate. Initially, injected [3H] folic acid was found converted to folate penta- and hexaglutamates in all fractions to a similar extent except in the microsomes where the percentage conversion was much less, as measured by the percentage of total 3H cpm determined to be [3H] folate penta- and hexaglutamates. At 24 h, the conversion of [3H] folates to penta- and hexaglutamates in each fraction was less than that found for the endogenous folates. Injected [3H] folic acid after 2h was found to consist of 94% reduced folates in the soluble fraction, 56% in the mitochondrial, 55% in the nuclear, 20% in the lysosomal, and 15% in the microsomal fraction.

Acid Phosphatase↗
PubMed1976

Rescue of a rat tropic rat hepatoma virus pseudotype Kirsten sarcoma virus by co-cultivation of hepatoma tissue culture cells with K-NRK cells.

A rat tropic rat hepatoma virus pseudotype Kirsten sarcoma virus has been rescued from a co-culture of rat hepatoma tissue culture cells, HTC-HI, with Kirsten murine sarcoma transformed non-producer rat kidney cells (K-NRK). The virus complex, RHHV-KiMSV, released from the co-culture exhibited cell transformation ability on normal rat kidney (NRK) cells and showed a restricted host range limited to rat embryo fibroblasts and other normal rat cell lines. Evidence derived from indirect immunofluorescence assays demonstrated the association of rat helper virus specific gs-I and gs-3 antigens with RHHV-KiMSV transformed cells. RHHVKiMSV is currently being cultured at a titre as high as 10(4) f.f.u./ml in tissue culture, and thus offering opportunity for biochemical studies of rat viruses.

Animals↗
PubMedDate not supplied

Surgical management of extrahepatic portal hypertension and variceal bleeding.

Variceal bleeding remains an important complication in extrahepatic portal vein thrombosis (EPVT). As for portal hypertension due to other etiologies, an elective treatment to decrease the risk of subsequent rebleeding is warranted. The results of the Sugiura-Futagawa procedure (SP) in 38 patients with variceal bleeding secondary to EPVT are reported: 20 women and 18 men, with a mean age of 28 +/- 2 years (SEM). Thirty-seven patients were classified as Child-Pugh class A, and one patient as class B. In terms of diagnosis, 45% of patients had idiopathic EPVT, and 18% had associated hypercoagulability disorders; 52% of patients had associated splenic vein thrombosis. The SP was completed in two surgical stages in 18 patients and in one surgical stage in 14; 6 patients had only the abdominal stage. One patient had mild postoperative encephalopathy, and three patients rebled at long-term follow-up study. There were two operative deaths. Actuarial survival was 70% at 64 months. It is concluded that the SP is an excellent alternative for patients with variceal bleeding secondary to EPVT.

Adult↗
PubMedDate not supplied

Comparison of ceftibuten vs. amoxicillin/clavulanic acid as antibiotic prophylaxis in cholecystectomy and/or biliary tract surgery.

A randomized, comparative, prospective clinical trial was carried out at a tertiary care center to compare the efficacy of two antibiotic regimens in the prophylaxis of postoperative infection in patients undergoing biliary tract surgery. One hundred patients undergoing cholecystectomy or biliary tract exploration were randomly allocated to one of the following antibiotic regimens: the standard regimen of three doses of amoxicillin/clavulanic acid (1000/200 mg) given by intravenous infusion, or a single dose of ceftibuten (400 mg) given orally. Patients were monitored during their stay in the hospital and over a 2 week period as outpatients. Fifty adult patients were included in each group. Mean age was 49 years, and sex distribution was 82 women and 18 men. The groups were comparable in terms of demographic characteristics and comorbidity. There were no cases of postoperative infection in the ceftibuten group, but five cases of infection occurred in the amoxicillin/clavulanic acid group (P < 0.05). No adverse effects were observed with either antibiotic. The treatment cost per patient was significantly lower for ceftibuten. The results indicate that ceftibuten is well tolerated and more effective than amoxicillin/clavulanic acid for prophylaxis following gallbladder and biliary tract surgery. In addition, ceftibuten has the advantage of being more cost-effective and easier to administer than amoxicillin/clavulanic acid so it could be considered as an alternative for antibiotic prophylaxis in these types of surgical procedures.

Administration, Oral↗
PubMedDate not supplied

Thy-1-mediated T-cell activation requires co-expression of CD3/Ti complex.

In addition to monoclonal antibodies against the CD3 (T3)-T-cell antigen receptor (CD3/Ti) complex, several other monoclonals directed towards distinct cell surface structures on human (CD2 (T11) and Tp44) and murine (Thy-1, TAP, and Ly-6) T lymphocytes are capable of activating T cells. It has been proposed that such structures may function as alternative pathways of stimulation. To examine directly whether any relationship exists between Thy-1-dependent activation phenomena and T-cell activation mediated through the CD3/Ti complex, we have transfected several CD3/Ti- variants of the human T-cell line Jurkat with the murine Thy-1.2 gene. Our data indicate that in CD3/Ti-, Thy-1.2+ transfectants, monoclonal antibodies against Thy-1.2 can induce a rise in cytoplasmic free calcium ([Ca2+]i), but fail to stimulate interleukin-2 (IL-2) production. The only defect in these variant cell lines responsible for the inability to produce IL-2 in response to Thy-1 stimulation was in the expression of the CD3/Ti complex, because replacement of defective Ti alpha- or beta-chain genes reconstributed both surface expression of CD3/Ti and responsiveness to Thy-1 in the IL-2 production assay.

Antigen-Antibody Complex↗
PubMedDate not supplied

Polaroid photorefractive screening of infants.

We modified a Polaroid SE camera for use as a photoretinoscope. A total of 187 infants between 2 and 18 months of age were photographed using this device. About half of these infants (97) participated in a double blind study in which the results of photorefraction were compared with those of standard cycloplegic retinoscopy. Eighty-three infants were photographed without cycloplegia. Thirty-four infants were photographed while cyclopleged. Photographs were evaluated for significant refractive errors and other ocular abnormalities. The effectiveness of the camera system to screen for significant refractive errors without the use of cycloplegia was assessed. Infants were identified to be at risk by photorefraction if, in any photograph, a hyperopic bright crescent calculated to be greater than or equal to +1.25 D was present in the pupil. Clinically significant refractive errors were defined by the results of cycloplegic retinoscopy: "at-risk" infants had either 3.5 D or more hyperopia in either eye, or astigmatism in either eye greater than or equal to 2.5 D, or anisometropia greater than or equal to 1.5 D. With these clinical criteria and the above photographic screening criterion, the camera's sensitivity and specificity were 83% and 69%, respectively. The present system compares favorably with earlier, more sophisticated units in alerting practitioners to potentially significant refractive errors in infants. Additionally, as a screening tool, this device offers the benefits of being inexpensive and easy to use, and of providing immediate feedback.

Calibration↗
PubMedDate not supplied

Carcinoid tumor of the hepatic duct presenting as a Klatskin tumor in an adolescent and review of world literature.

This is a case presentation of a 14-year-old boy with the radiological diagnosis of cholangiocarcinoma occluding the hepatic duct bifurcation. His only symptom at presentation was jaundice and further workup confirmed a mass at the porta hepatis. Surgical treatment resulted in a resection of the hepatic bifurcation tumor with a final pathological diagnosis of a carcinoid tumor of the hepatic duct bifurcation. To our knowledge, this is only the second case presented of a resected carcinoid tumor in adolescence. In this communiqué we present the above case and review of the world literature of biliary neuroendocrine tumors.

Adolescent↗
PubMedDate not supplied

Management of choledocholithiasis found during laparoscopic cholecystectomy: a strategy based on the use of postoperative endoscopic retrograde cholangiography and sphincterotomy.

BACKGROUND: Several strategies have been proposed for the diagnosis and management of common bile duct stones in candidates for laparoscopic cholecystectomy. METHODS: Clinical characteristics, treatment, and outcome of five patients in whom CBDS were demonstrated by intraoperative cholangiography during a laparoscopic cholecystectomy were analyzed. All patients were treated by endoscopic sphincterotomy. Post-treatment outcome was emphasized. RESULTS: Mean age of the patients was 55 years. Four were female and one male. Preoperative liver function tests were within normal range in all patients. Duct stones of a mean size of 0.8 cm were found in the lower third of the biliary tree. Four were retrieved by endoscopic sphincteroplasty using a Dormia basket and in one patient after an unsuccessful endoscopic attempt, an open choledochoduodenostomy was performed. There were no post-treatment complications. At a mean follow-up of 2 years no evidence of recurrent common bile duct obstruction has been found in any patient. CONCLUSIONS: This small series supports the use of postoperative endoscopic retrograde cholangiography and sphincteroplasty in patients with unsuspected common bile duct stones found during laparoscopic cholecystectomy. Retrieval of the stones immediately after surgery at the operative room is recommended.

Adult↗
PubMedDate not supplied

[Undifferentiated (embryonal) sarcoma of the liver. Report of a case].

A 15-year-old woman who was studied because an abdominal mass at the Instituto Nacional de la Nutricion Salvador Zubiran (INNSZ) is reported. The history revealed only malaise and mild abdominal pain. At physical exploration, an abdominal mass in the upper right quadrant was found. Liver function tests were normal. Abdominal ultrasound and computerized tomography revealed a large cystic mass of the right hepatic lobe. She underwent exploratory laparotomy. Intraoperative frozen sections of the biopsies demonstrated undifferentiated sarcoma of the liver, and an extended right trisegmentectomy was performed. Postoperative outcome was uneventful. Adjuvant treatment with doxorubicin and dacarbazine was given, and at six months of follow-up, the patient is alive without any evidence of recurrence. Clinical and histopathologic features of this rare malignant tumor are discussed, as well as the therapeutic choices.

Adolescent↗
PubMedDate not supplied

[Duodenal cancer].

UNLABELLED: To analyze the general characteristics and outcome of a cohort of 6 patients with malignant duodenal tumors who underwent surgical radical resection. DESIGN: Longitudinal retrolective study. SETTING: A third level medical center. RESULTS: Mean age was 48 years. M/F ratio was 2:1. The most frequent symptom was duodenal obstruction. Mean time between the beginning of the symptoms and the correct diagnosis was 15 months. Five of six patients demonstrated abnormalities on gastrointestinal X rays. All patients underwent Whipple resection, this was curative in 2, palliative in 2 more and not evaluated in two cases due to operative mortality. Five tumors were adenocarcinomas and one a carcinoid tumor. The long-term mortality occurred in 2 patients. CONCLUSIONS: The diagnosis of primary duodenal carcinoma needs a deep clinical suspicion, some patients when treated by radical resection may experience long-term survival.

Adenocarcinoma↗