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H Chun

Publications and source records attributed to H Chun.

34 records · Page 2Linked to original sources
PubMed1994

Producing exposed coat-free embryos.

Production of embryos that are free of tough outer coats facilitates studies that are not possible with embryos surrounded by impenetrable envelopes. This report describes a new procedure for preventing formation of fertilisation membranes in the sea urchin (Lytechinus pictus) model. This procedure involves treating unfertilised eggs with the enzyme alpha-amylase, which cleaves alpha-1,4 glucosidic bonds in the vitelline layer. A major advantage of this method is that it is very well defined and completely controllable with alpha-amylase inhibitor. The results suggest that intact alpha-1,4 glucosidic bonds are essential for vitelline layer integrity required for formation of the fertilisation membrane. Eggs treated with alpha-amylase possessed the same surface lectin receptors as untreated eggs and, as shown by light and transmission electron microscopy, produced healthy, cleaving embryos that were free of fertilisation envelopes.

Animals↗
PubMed1994

Atrioventricular node reentry: current concepts and new perspectives.

With the advent of RF catheter modification of AV node conduction for the treatment of AV node reentrant tachycardia, considerable advances have been made with better understanding of the AV junctional anatomy, electrophysiology, and mechanism responsible for AV node reentrant tachycardia. Future studies should be designed to uncover the basic cellular electrophysiological mechanisms responsible for fast and slow AV node conduction, to define the exact tissue components of the reentrant circuit in order to make ablative procedures safer, and to study the long-term effects of RF catheter ablation on AV conduction. Special caution should be directed toward pediatric patients with more stringent indications for catheter ablation of the AV junctional area in these patients.

Animals↗
PubMed1994

Comparison of updated Vitek Yeast Biochemical Card and API 20C yeast identification systems.

The updated Vitek Yeast Biochemical Card (YBC) was compared with the API 20C by using 409 germ tube-negative yeasts and Geotrichum spp. that were either clinical or proficiency sample isolates. The API 20C was the reference standard. The 409 isolates represented nine genera and 21 species. Morphology agars were inoculated and interpreted for each isolate. The API 20C identified 406 isolates (99.3%), while the Vitek YBC identified 367 (89.7%). Both systems identified the majority of yeasts after 24 h of incubation--73.4% were identified by the API 20C and 77.4% were identified by the Vitek YBC. The Vitek 24-h reading had some incorrect identifications. These included 14 isolates of Candida tropicalis that were identified as Candida parapsilosis (91 to 97% reliability) and 3 isolates of Candida krusei that were called Blastoschizomyces capitatus (Geotrichum capitatum), Candida rugosa, and Candida zeylanoides. In total, the Vitek YBC misidentified 30 isolates, while the API 20C misidentified 3 isolates. In addition, results for 14 isolates with the Vitek YBC were listed under the category "no identification." Morphology agars were required for identification with 89 isolates (21.9%) when the API 20C was used and with 50 isolates (12.6%) when the Vitek YBC was used. Apart from the price of the Vitek instrument, the API 20C costs $1.28 more per test than the Vitek YBC. Overall, the updated Vitek YBC compares favorably with the API 20C in the identification of common yeasts such as Torulopsis glabrata, C. parapsilosis, and Cryptococcus neoformans. However, problems were encountered with the Vitek system in the identification of C. tropicalis, C. krusei, Trichosporon spp., and some Cryptococcus spp. The routine use of morphology agars with either method is recommended.

Agar↗
PubMed1994

Phase I-II trial of high dose Ara-C, carboplatinum, etoposide and steroids in patients with refractory or relapsed lymphomas.

Thirty-three patients, including 20 with non-Hodgkin's lymphomas (NHL) and 13 patients with Hodgkin's disease, were treated with a combination of high dose Ara-C 3 gm/m2 over 3 h, carboplatinum 300 mg/m2 over 15 min, etoposide 300-750 mg/m2 continuous infusion over 24 h and solumedrol 1250 mg. Probantheline was given prophylactically. The etoposide dose was escalated from 300 mg/m2 to 600 mg/m2 to 750 mg/m2. The median age was 44 years (range 28-63). Median Karnofsky performance status was 80 (range 60-100). Patients treated included: primary refractory six, first relapse 14, > first relapse seven, and resistant relapse six. Responses were seen in 11 patients (33%; 95% CI 17-49). Of note, no responses were seen in ten patients receiving < 750 mg/m2 etoposide vs. 11/23 patients receiving 750 mg/m2 etoposide (p = 0.013). Responses were seen in patients who were refractory to previous chemotherapy and occurred in all sites. Toxicity was tolerable with most patients not requiring hospitalization following chemotherapy. Two patients died on study: one of Guillain-Barre syndrome and the other of a sudden death. Severe mucositis was not observed. High dose etoposide based salvage chemotherapy offers a greater probability of response than lower dose etoposide. This regimen is well tolerated and can be administered with relatively brief hospitalization.

Adult↗
PubMed1993

Propantheline prevention of mucositis from etoposide.

Mucosal toxicity is dose limiting for etoposide. This may be related to the direct effects of etoposide on the mucosa. Twelve patients receiving etoposide 1800 mg/m2 as part of a myeloablative pre-transplant regimen were randomized to receive propantheline 30 mg or placebo orally every 6 h for six doses. Mucositis was less frequent (2 of 6 vs 5 of 6) and less severe (p = 0.05) in the propantheline arm. There were no differences in tumor response or survival between the two groups. Propantheline is an anticholinergic that causes xerostomia by decreasing salivation. Propantheline may reduce the salivary excretion of etoposide and could reduce its toxic effects on the mucosa. Propantheline is effective in reducing the incidence and severity of mucositis in patients receiving high-dose etoposide.

Adult↗
PubMed1992

Homoharringtonine is safe and effective for patients with acute myelogenous leukemia.

Homoharringtonine (HHT) is a cephalotaxine alkaloid with reported efficacy in acute myelogenous leukemia (AML). In a phase II trial, we evaluated HHT 5 mg/m2 by continuous infusion daily for 9 days in patients with relapsed or refractory acute leukemia and blastic phase of chronic myelogenous leukemia (BLCML). Sixty-six patients were entered. There were 40 males and 26 females with a median age of 41 years (range 15-81). Of 43 patients with relapsed AML, seven achieved a complete remission (16%, 95% confidence interval 5%-27%). Although 11 patients with AML primarily resistant to an anthracycline/cytarabine combination did not respond, two of three patients primarily resistant to low-dose cytarabine achieved complete remission. No patients with acute lymphoblastic leukemia, biphenotypic leukemia, or BLCML responded. Hypotension during the administration of HHT was the most difficult toxicity encountered, requiring multiple interruptions of therapy in several patients and the administration of intravenous saline. Fluid retention and weight gain occurred in 29% of patients. Transient asymptomatic hyperglycemia was observed in 63% of patients. Other toxicity was mild and included nausea and vomiting, diarrhea, mucositis, hepatic dysfunction, and cardiac arrhythmias. As expected, severe myelosuppression occurred in all patients. HHT is well tolerated, but with unique problems associated with administration. It has demonstrable efficacy in pre-treated patients with AML, but its role in the treatment of this disease remains to be defined.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Homoharringtonine in combination with cytarabine for patients with acute myelogenous leukemia.

Homoharringtonine (HHT) is one of several cephalotaxine alkaloids that has shown clinical efficacy in patients with acute myelogenous leukemia (AML). In a phase I trial we evaluated cytarabine 100 mg/m2 by continuous infusion daily for 7 days in combination with four dose levels of HHT ranging from 1.5-5 mg/m2 by continuous infusion daily for 7 days to see if an effective regimen could be developed. Twenty-two patients with relapsed and/or primary refractory AML were treated. Seventeen males and five females were treated, with a median age of 40 years (range 19-63). There were five remissions in 14 patients with relapsed AML and none of eight responders in patients with primary refractory AML. None of the three patients treated at 1.5 mg/m2 dose level of HHT responded. Of three patients treated at the 3 mg/m2 dose level, there was one complete remission. At both 4 mg/m2 and 5 mg/m2, two of eight patients achieved complete remission. Four of the five remissions occurred in patients with acute promyelocytic leukemia. Drug induced pancytopenia was universal, and hypotension and fluid retention were more common at the higher dose levels. Other toxicity was mild and included nausea, vomiting, diarrhea, and mucositis. No significant hepatic, renal, or cardiac toxicity was seen. We conclude that the dose of HHT 4 mg/m2 for 7 days by continuous infusion in combination with cytarabine is safe for patients with AML; and this combination is appropriate for a phase II evaluation.

Adult↗
PubMed1992

Humoral antimelanoma immunity: induction by mouse antiidiotypic mAb, MK2-23 and association with survival of patients with advanced melanoma.

This study has shown that a mouse antiidiotypic mAb bearing a mirror image of HMW-MAA can break tolerance to a well-defined self HMW-MAA and can induce humoral anti HMW-MAA immunity in patients with melanoma. Furthermore, the induction of an immune response to a well-defined melanoma-associated antigen has been shown to be associated with a favorable clinical response. If this association reflects a cause-effect relationship between the two parameters, the anti HMW-MAA immunity induced by mouse antiidiotypic mAb MK2-23 may effect immune destruction of melanoma cells and may interfere with the metastatic potential of those cells because of the suggested role of HMW-MAA in this phenomenon.

Animals↗
PubMed1990

Phase II trial of fludarabine phosphate (F-Ara-AMP) in patients with advanced head and neck cancer.

Thirteen patients with advanced head and neck cancer were entered into a phase II study of fludarabine phosphate. Fludarabine phosphate was given by continuous infusion for 5 days, at a starting dose of 20 mg/m2 per day for patients previously treated with one regimen and 25 mg/m2 per day for previously untreated patients; therapy was repeated every 3-4 weeks. Of the 13 patients, 3 had undergone one prior regimen and 10 patients were previously untreated by chemotherapy. No responses were observed. Myelosuppression was the most common toxicity observed. Four patients developed mild nausea, vomiting and seven developed bleeding stomatitis that resolved in one week. In addition, four patients developed headaches which resolved spontaneously. No renal, hepatic, or neurotoxicity was observed. Our study demonstrates that in previously treated and untreated patients, fludarabine phosphate given on this schedule has little activity in patients with advanced head and neck cancer.

Aged↗
PubMed1985

Phase I evaluation and pharmacokinetic study of weekly iv thymidine and 5-FU in patients with advanced colorectal carcinoma.

A phase I study of weekly iv thymidine (TdR) and 5-FU was carried out in patients with advanced colorectal carcinoma using two dosage schedules. Schedule 1 employed a 3-hour infusion of TdR (6-8 g/m2/hour) followed immediately by a bolus of 5-FU (100-200 mg/m2). Schedule 2 used a slightly larger dose of TdR (18 g/m2/hour for 1.5 hours), with 5-FU given 30 minutes after the TdR infusion was started. Myelosuppression was observed erratically at the higher doses of 5-FU. Diarrhea and severe fatigue were seen frequently with Schedule 1. CNS side effects were the dose-limiting effects for both schedules. For long-term use the maximally tolerated 5-FU doses were 100 mg/m2/week for Schedule 1 and 175 mg/m2/week for Schedule 2. In pharmacokinetic studies in five patients, both schedules produced prolonged plasma beta-half-lives of 5-FU (96-189 minutes). Extensive formation of floxuridine was seen with both schedules. It appears likely that CNS toxic effects are characteristic of TdR-containing 5-FU regimens and would limit the therapeutic potential of this approach.

Adult↗
PubMed1984

Hepatic artery pump infusion: toxicity and results in patients with metastatic colorectal carcinoma.

5-Fluorodeoxyuridine (FUDR) was infused continuously into the hepatic artery for 14 days a month at an initial dose of 0.3 mg/kg per day in 45 patients with liver metastases from colorectal carcinoma. In 41 adequately treated patients, partial responses (greater than 50% tumor regression) were observed in 12 (52%) of 23 previously untreated patients, and three (17%) of 18 previously treated patients. Severe gastrointestinal toxicity was endoscopically documented in 19 (46%) patients; 12 (29%) had discrete ulcers, and seven had diffuse gastritis or duodenitis. Significant hepatic-enzyme abnormality was seen in 29 patients (71%) and an elevated serum bilirubin in nine (22%). A significant factor influencing survival was the extent of tumor involvement in the liver; patients with less than 20% involvement have not yet reached a median survival at 13 months versus six months for patients with greater than 60% involvement (p less than 0.001). Studies comparing regional to systemic chemotherapy and stratifying patients according to the extent of hepatic tumor burden are needed to assess the true impact of hepatic infusion on response and survival.

Adenocarcinoma↗