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Biomedical subjects

J Donegan

Publications and source records attributed to J Donegan.

13 recordsLinked to original sources
PubMed1998

Phase II trial of paclitaxel, fluorouracil, and cisplatin in patients with advanced carcinoma of the esophagus.

PURPOSE: We have previously identified paclitaxel as an active single agent in the treatment of esophageal cancer. We performed a phase II trial of paclitaxel in combination with cisplatin and fluorouracil (5-FU), conventionally used chemotherapy for esophageal cancer. The antitumor response, toxicity, and survival of patients treated with the three-drug regimen were evaluated. PATIENTS AND METHODS: Sixty-one patients with advanced, surgically unresectable, or metastatic squamous cell or adenocarcinoma of the esophagus were treated. No prior chemotherapy was allowed. Thirty patients had adenocarcinoma and 31 patients had squamous cell carcinoma. The majority (47 patients; 77%) had metastatic disease and 14 patients (23%) had an unresectable primary or locally recurrent tumor. Patients received paclitaxel 175 mg/m2 by 3-hour infusion day 1; cisplatin 20 mg/m2 daily days 1 through 5, and 5-FU by continuous infusion at a dose of 1,000 mg/m2 daily days 1 through 5. Because of toxicity observed in the first 10 patients treated, the starting dose of 5-FU was subsequently reduced to 750 mg/m2 daily in the remaining patients. A planned attenuation of cisplatin to 15 mg/m2 daily was made after the first three cycles. Granulocyte colony-stimulating factor (G-CSF) was not routinely administered unless the patient had an episode of febrile neutropenia or prolonged grade 4 neutropenia. Treatment was recycled every 28 days. RESULTS: Sixty-one patients completed a median of five cycles, and 60 patients were assessable for response. Major responses were seen in 29 patients (48%; 95% confidence intervals, 35 to 61), which included seven complete responses (12%). Comparable response rates were seen for patients with adenocarcinoma (46%) and those with squamous carcinoma (50%), and for patients with metastatic disease (22 of 46 patients; 48%) and those with locally advanced disease (seven of 14 patients; 50%). A significantly higher complete response rate was observed in patients with squamous carcinoma (20%) compared with those with adenocarcinoma (3%; chi2 P=.04). The median duration of response was 5.7 months (range, 1 to 18.6 months). Median survival was 10.8 months (range, 1.5 to 25 months). Toxicity was severe but manageable with dose attenuation, and included 18% of patients with grade 3 neurologic toxicity. Twenty-eight patients (46%) required a dose attenuation for toxicity, and 42 of 275 treatment cycles (15%) required a dose attenuation. Twenty-nine patients (48%) required hospitalization for toxicity, which included 11 patients for neutropenic fever (18%). There were no treatment-related deaths. CONCLUSION: The combination of paclitaxel, cisplatin, and 5-FU has substantial antitumor activity in metastatic esophageal carcinoma, with a remarkable complete response rate noted in patients with squamous carcinoma. Paclitaxel is an important new agent in the treatment of esophageal carcinoma, and further evaluation of this agent in combination chemotherapy is warranted. Given the toxicity associated with the current regimen, the optimal dose and schedule of paclitaxel in combination chemotherapy remain to be established.

Adenocarcinoma↗
PubMed1997

Stable human immunodeficiency virus type 1 (HIV-1) resistance in transformed CD4+ monocytic cells treated with multitargeting HIV-1 antisense sequences incorporated into U1 snRNA.

We have approached the development of a human immunodeficiency virus type 1 (HIV-1) therapeutic product by producing immune cells stably resistant to HIV-1. Promonocytic CD4+ cells (U937) were made resistant to HIV-1 by the introduction of a DNA construct (pNDU1A,B,C) that contained three independent antisense sequences directed against two functional regions, transactivation response and tat/rev, of the HIV-1 target. Each sequence was incorporated into the transcribed region of a U1 snRNA gene to generate U1/HIV antisense RNA. Stably transfected cells expressed all three U1/HIV antisense transcripts, and these transcripts accumulated in the nucleus. These cells were subjected to two successive challenges with HIV-1 (BAL strain). The surviving cells showed normal growth characteristics and have retained their CD4+ phenotype. In situ hybridization assays showed that essentially all of the surviving cells produced U1/HIV antisense RNA. No detectable p24 antigen was observed, no syncytium formation was observed, and PCR-amplified HIV gag sequences were not detected. Rechallenge with HIV-1 (IIIB strain) similarly yielded no infection at a relatively high multiplicity of infection. As a further demonstration that the antisense RNA directed against HIV-1 was functioning in these transfected immune cells, Tat-activated expression of chloramphenicol acetyltransferase was shown to be specifically inhibited in cells expressing Tat and transactivation response region antisense sequences.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Nonradioactive, colorimetric microplate hybridization assay for detecting amplified human immunodeficiency virus DNA.

A nonradioactive, colorimetric microplate hybridization procedure was used to assay human immunodeficiency virus (HIV) DNA, amplified by the polymerase chain reaction (PCR). Under the PCR conditions used, four proviral copies per 150,000 cells were detected by amplifying a series of DNA mixtures that contained various copy numbers of HIV. Assays of PCR-amplified DNA from peripheral blood mononuclear cells of seronegative individuals yielded negative results (104 of 104), whereas samples from seropositive individuals yielded > 99% positive results (141 of 142). Similar results were obtained in a chemiluminescent assay with an acridinium ester-labeled probe and in a solution hybridization assay in which a 32P-labeled probe was used.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Variability in the proliferative potential of human gliomas.

One hundred forty-three patients with gliomas of astrocytic origin (61 with glioblastomas multiforme (GM) and 82 with astrocytomas) received an intravenous infusion of bromodeoxyuridine (BUdR), 150-200 mg/m2 at the time of surgery, to label tumor cells undergoing DNA synthesis. BUdR-labeled cells were identified by the indirect immunoperoxidase method using anti-BUdR monoclonal antibodies. The percentage of BUdR-labeled cells, or BUdR labeling index (LI), was calculated by microscopic examination of selected viable areas of the tissue sections. The GMs had a median LI of 7.5%, and three quarters of these tumors had LIs greater than 5%. Highly anaplastic astrocytomas (HAAs) and moderately anaplastic astrocytomas (MoAAs) had median LIs of 2.3% and less than 1%, respectively. Among the HAAs, the LI was 1% to 5% in 56% of tumors, greater than 5% in 26%, and less than 1% in 18%. More than 60% of MoAAs had LIs less than 1%, which agrees with the slow clinical progression of this type of tumor, and the remainder had LIs of 1.4% to 9.3%. These results show that histopathologically similar tumors may have different proliferative potentials. Measuring the proliferative potential of individual gliomas is therefore crucial for predicting the prognosis more accurately and for devising more tumor-specific treatment regimens for individual patients.

Astrocytoma↗
PubMed1986

CPR 1986.

Explore the source record for details and available documents.

Adult↗
PubMed1985

The ilvB locus of Escherichia coli K-12 is an operon encoding both subunits of acetohydroxyacid synthase I.

The ilvB locus of Escherichia coli K-12 encloses two open reading frames defining polypeptides of 60,000 and 11,200 molecular weight. The entire locus, about 2.3 kb, is co-transcribed as an operon. The molecular weights and amino acid compositions of the presumptive operon polypeptides agree with those of the large and small subunit polypeptides of acetohydroxyacid synthase (AHAS) I, for which ilvB is the structural locus. We reserve the designation ilvB for the promoter proximal (longer) cistron and designate the promoter distal cistron ilvN. The molecular weight and amino acid sequence of the ilvB polypeptide are strikingly similar to those of the I1vI (larger subunit of AHAS III) and I1vG (larger subunit of AHAS II) polypeptides. There is less size uniformity among the I1vN, I1vH (smaller subunit of AHAS III), and I1vM (smaller subunit of AHAS II) polypeptides. Nevertheless, there is significant amino acid sequence homology among the three small subunit polypeptides. Thus, all three AHAS isozymes of E. coli K-12 probably have a common evolutionary origin.

Acetolactate Synthase↗
PubMed1984

Characterization of a ts mutant of BALB/3T3 cells and correction of the defect by in vitro addition of extracts from wild-type cells.

ts20 is a temperature-sensitive mutant cell line derived from BALB/3T3 cells. DNA synthesis in the mutant decreased progressively after an initial increase during the first 3 h at the restrictive temperature. RNA and protein synthesis increased for 20 h and remained at a high level for 40 h. Cells were arrested in S phase as determined by flow microfluorimetry, and DNA chain elongation was retarded as measured by fiber autoradiography. Infection with polyomavirus did not bypass the defect in cell DNA synthesis, and the mutant did not support virus DNA replication at the restrictive temperature. After shift down to the permissive temperature, cell DNA synthesis was restored whereas virus DNA synthesis was not. Analysis of virus DNA synthesized at the restrictive temperature showed that the synthesis of form I and replicative intermediate DNA decreased concurrently and that the rate of completion of virus DNA molecules remained constant with increasing time at the restrictive temperature. These studies indicated that the mutation inhibited ongoing DNA synthesis at a step early in elongation of nascent chains. The defect in virus and cell DNA synthesis was expressed in vitro. [3H]dTTP incorporation was reduced, consistent with the in vivo data. The addition of a high-salt extract prepared from wild-type 3T3 cells preferentially stimulated the incorporation of [3H]dTTP into the DNA of mutant cells at the restrictive temperature. A similar extract prepared from mutant cells was less effective and was more heat labile as incubation of it at the restrictive temperature for 1 h destroyed its ability to stimulate DNA synthesis in vitro, whereas wild-type extract was not inactivated until incubated at that temperature for 3 h.

Animals↗
PubMed1980

Clinical cerebral blood flow measurement with inhaled xenon and CT.

Cerebral blood flow measurement has not yet been attempted with xenon and CT in patients. Xenon washout was studied in three patients receiving subanesthetic concentrations of xenon. Cerebral enhancement after 30%--50% inhaled xenon was demonstrated without serious side effects. Clinical cerebral blood flow measurements with xenon and CT may be feasible.

Cerebrovascular Circulation↗
PubMed1976

Training in advanced cardiac life support.

The nationally recognized training and certification program in Advanced Cardiac Life Support consists of lecture material and a new concept in training and testing for the practical skills of Advanced Cardiac Life Support. The course content follows closely the concepts of advanced life support as explained in the standards on cardiopulmonary resuscitation and emergency cardiac care.

Allied Health Personnel↗