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Biomedical subjects

J Willey

Publications and source records attributed to J Willey.

At least 19 recordsLinked to original sources
PubMed2005

Elucidating determinants of the plateau in oxygen consumption at VO2max.

BACKGROUND: A plateau in oxygen consumption (VO2) is the primary means of confirming that maximal oxygen uptake (VO2max) is attained during incremental exercise to fatigue. However, it is still unresolved what causes expression of a plateau in VO2 at the end of incremental exercise. OBJECTIVES: To elucidate incidence and identify determinants of the VO2 plateau in subjects of varying fitness. METHODS: Thirty subjects (mean (SD) age and VO2max 26.9 (9.8) years and 3.4 (0.8) litre/min respectively) were separated into three groups: endurance trained (ET; n = 9), recreationally active (Rec; n = 11), and strength/sprint trained (STR; n = 10). During three separate visits, subjects completed incremental treadmill exercise during which breath by breath gas exchange data were obtained. Body composition was measured using a three site skinfolds model. Force production of the knee extensors and flexors was assessed using isokinetic dynamometry. RESULTS: VO2max was significantly higher (p < 0.05) in the ET group vs STR and Rec. The change in VO2 (DeltaVO2) at VO2max was not different (p > 0.05) in the ET group (33.0 (27.3) ml/min) compared with the Rec group (30.3 (24.1) ml/min) and the STR group (44.4 (23.8) ml/min). No correlations (p > 0.05) were evident between DeltaVO2 at VO2max and VO2max (r = 0.05), fat-free mass (r = 0.12), and muscular strength (r = -0.12). CONCLUSIONS: The incidence of a plateau in VO2 at VO2max (from correlation data) is not due to factors related to training status or physical fitness of subjects, but is altered by analysis and interpretation of gas exchange data.

Adolescent↗
PubMed2001

Phase I study of vinorelbine and paclitaxel by 3-hour simultaneous infusion with and without granulocyte colony-stimulating factor support in metastatic breast carcinoma.

BACKGROUND: The purpose of the study was to determine the maximum tolerated dose (MTD) of vinorelbine and paclitaxel given concomitantly in patients with advanced breast carcinoma, the toxicity of this combination, and whether the addition of granulocyte colony-stimulating factor (G-CSF) would allow administration of higher doses of the combination. METHODS: Between January 1994 and January 1995, 38 patients were entered on this study. All patients received vinorelbine and paclitaxel administered simultaneously over 3 hours and repeated every 21 days as frontline therapy for metastatic breast carcinoma. Twenty-five patients (Group 1) did not receive prophylactic G-CSF, and 13 patients (Group 2) received prophylactic G-CSF. Toxic effects were documented prospectively using the National Cancer Institute grading system. RESULTS: One hundred eighty-seven (Group 1) and 111 (Group 2) cycles were administered. For Group 1, Grade 3-4 granulocytopenia was encountered in 72% of the cycles and neutropenic fever in 30% of the cycles. For Group 2, Grade 3-4 granulocytopenia and neutropenic fever were encountered in 23% and 4% of the cycles, respectively. Grade 3-4 fatigue and myalgia, respectively, were encountered in 11% and 3% of the cycles in Group 1, whereas they were reported in 12% and 1% of the cycles in Group 2. The MTD of this combination without prophylactic G-CSF was 25 mg/m2 of vinorelbine and 150 mg/m2 of paclitaxel, the dose-limiting toxicity (DLT) being neutropenic fever and myalgia. The MTD of this combination with G-CSF was 36 mg/m2 of vinorelbine and 150 mg/m2 of paclitaxel, the DLT being myalgia and fatigue. CONCLUSIONS: The authors conclude that vinorelbine and paclitaxel can be safely administered concomitantly and are well tolerated. Phase II studies are recommended to test the efficacy of this schedule.

Adult↗
PubMed2001

Visuospatial attention: the role of target contrast and task difficulty when assessing the effects of cues.

Cueing paradigms have become popular in assessing the processes of attention. In two experiments we manipulated (i) the contrast of the target, and (ii) the similarity between the targets discriminated. We used a cue that would isolate the exogenous component of attention. Both a reduction in target contrast and an increase in target similarity raised overall reaction times by a similar amount; however, the target contrast manipulation produced a much greater cueing effect compared with the target similarity manipulation. The results suggest that manipulation of target contrast changes the attention cueing effect at a stage of attracting attention to a location of the target (the 'move' stage), rather than at a later processing stage.

Adolescent↗
PubMed2001

Use of an immunoassay as a means to detect polychlorinated biphenyls in animal fat.

In this paper we describe the validation and utilization of the Hybrinzme DELFIA immunoassay for detecting polychlorinated biphenyls (PCBs) in animal fat. The immunoassay incorporates a rapid sample processing protocol that has been optimized to detect concentrations of PCBs in animal fat at or above 200 ng/g. The limit of detection of the assay was less than 50 ng/g. When the action level for the DELFIA assay was set at 100 ng/g to detect samples having 200 ng/g or more PCBs, the false negative rate was estimated at 0.2%. The false positive rate depends on the concentration of PCBs in the sample population and was estimated at 4% and 7% for samples having 10 ng/g and 20 ng/g PCBs, respectively. By utilizing the DELFIA assay system to select for positive samples and GC/MS analysis for confirmation analysis, an accurate and cost-effective programme has been established for the high throughput detection of PCBs in animal products.

Adipose Tissue↗
PubMed2001

Phase I-II vinorelbine (Navelbine) by continuous infusion in patients with metastatic breast cancer: cumulative toxicities limit dose escalation.

Vinorelbine (Navelbine) has significant activity against breast carcinoma and is less neurotoxic than vinblastine. Because vinblastine has improved activity when administered by continuous infusion, we conducted a Phase I-II study to determine the maximum tolerated dose (MTD) of vinorelbine when given by continuous infusion and the response rates to it in heavily pretreated metastatic breast cancer patients. Between April 1994 and August 1997, 87 patients were entered in the study. All were female and had proven metastatic breast cancer. Ninety-five percent of them had received prior doxorubicin treatment, and 74% had received prior paclitaxel treatment. In Phase I of the study, all patients received 8 mg of vinorelbine by intravenous (i.v.) bolus followed by a continuous infusion of vinorelbine over 96 hr. When the MTD was determined, patients were entered in the Phase II arm to assess treatment responses and cumulative toxic reactions. In the Phase I arm (43 patients, 182 cycles), we determined the MTD of vinorelbine to be 8 mg by i.v. bolus followed by a continuous infusion of 11 mg/m2/day over 4 days. The dose-limiting toxic reaction was grade 3-4 granulocytopenia in 35% of the cycles and neutropenic fever in 15% of the cycles. Forty-four patients (193 cycles) were treated at the MTD. Seven (16%) of them had a response (2 complete responses, 5 partial responses). The median durations of response and survival were 4.3 and 8.6 months, respectively. However, cumulative toxic reactions (neutropenic fever and stomatitis) in 22 patients (50%) required dose reductions. A continuous infusion of vinorelbine can be safely administered but with a narrow therapeutic index because of cumulative toxic reactions. We recommend a modified MTD of vinorelbine: 8 mg by i.v. bolus followed by a continuous infusion of 10 mg/m2/day over 4 days. However, this treatment schedule offers no apparent advantage over the commonly used weekly vinorelbine schedule.

Adult↗
PubMed2001

Hantavirus nucleocapsid protein oligomerization.

Hantaviruses are enveloped, negative-strand RNA viruses which can be lethal to humans, causing either a hemorrhagic fever with renal syndrome or a hantaviral pulmonary syndrome. The viral genomes consist of three RNA segments: the L segment encodes the viral polymerase, the M segment encodes the viral surface glycoproteins G1 and G2, and the S segment encodes the nucleocapsid (N) protein. The N protein is a 420- to 430-residue, 50-kDa protein which appears to direct hantavirus assembly, although mechanisms of N protein oligomerization, RNA encapsidation, budding, and release are poorly understood. We have undertaken a biochemical and genetic analysis of N protein oligomerization. Bacterially expressed N proteins were found by gradient fractionation to associate not only as large multimers or aggregates but also as dimers or trimers. Chemical cross-linking of hantavirus particles yielded N protein cross-link products with molecular masses of 140 to 150 kDa, consistent with the size of an N trimer. We also employed a genetic, yeast two-hybrid method for monitoring N protein interactions. Analyses showed that the C-terminal half of the N protein plus the N-terminal 40 residues permitted association with a full-length N protein fusion. These N-terminal 40 residues of seven different hantavirus strains were predicted to form trimeric coiled coils. Our results suggest that coiled-coil motifs contribute to N protein trimerization and that nucleocapsid protein trimers are hantavirus particle assembly intermediates.

Amino Acid Motifs↗
PubMed2000

Phase I study of vinorelbine by 96-hour infusion in advanced metastatic breast cancer.

The purpose of this study was to evaluate the maximum tolerated dose and the toxicity profile of vinorelbine administered by continuous infusion for 96 hours to patients who had received prior chemotherapy for metastatic breast cancer. Forty-three patients with metastatic breast cancer were treated with vinorelbine 8 mg intravenously for 10 minutes (day 1) followed by continuous infusion of vinorelbine for 96 hours. Treatments were repeated every 3 weeks. Eighty-eight percent of the patients had had two or more prior chemotherapeutic regimens: 91% had prior doxorubicin therapy and 77% had prior paclitaxel therapy. All 43 patients were evaluable for toxicity. The median age was 49 years. All patients had a performance status less than or equal to 2 and a life expectancy more than 12 weeks. Eight dose levels were evaluated, and a total of 182 cycles were given. National Cancer Institute grade III or IV granulocytopenia was observed in 64 (35%) cycles, neutropenic fever in 27 (15%) cycles, fatigue (National Cancer Institute grade III or IV) in 18 (10%) cycles, and hand-foot syndrome in 8 (4%) cycles. In 17 (9%) cycles, patients were hospitalized. The maximum tolerated dose of this regimen was determined to be vinorelbine 8 mg intravenously for 10 minutes (day 1) followed by continuous vinorelbine infusion 11 mg/m2 for 96 hours. The dose-limiting toxicity was neutropenic fever and stomatitis.

Adult↗
PubMed1999

Phase II study of vinorelbine administered by 96-hour infusion in patients with advanced breast carcinoma.

BACKGROUND: Vinorelbine given by weekly bolus injection is active and less toxic than bolus vinblastine in the treatment of patients with metastatic breast carcinoma. Vinblastine given by 5-day continuous infusion showed a steep dose-response curve. Pharmacokinetic studies of vinorelbine showed that it is possible to achieve a comparable antitumor effect with a smaller amount of the drug if it is given by continuous infusion. The purpose of this study was to determine the efficacy of vinorelbine given by 96-hour continuous infusion to patients with refractory metastatic breast carcinoma patients. METHODS: Between May 1996 and August 1997, 47 patients with metastatic breast carcinoma were registered into the study. All patients previously had received doxorubicin and 70% had undergone prior paclitaxel treatment. Approximately 56% of the patients had >/=2 metastatic sites. All patients received vinorelbine according to the following dose schedule: 8 mg bolus followed by 11 mg/m(2) by continuous infusion over 24 hours every 4 days every 3 weeks. RESULTS: Forty-four patients were evaluable for response. A total of 193 cycles were administered. The overall response rate was 16% (2 patients achieved a complete response and 5 patients achieved a partial response). The median duration of response was 4.3 months and the median overall survival was 8.6 months. Patients with visceral metastases and/or multiple sites of involvement had shorter durations of response than patients with only soft tissue disease or single-site metastasis (3.1 months vs. 4. 9 months) and shorter overall survival (8.1 months vs. 12 months). Dose reductions were necessary due to cumulative stomatitis and/or fatigue in 12 cycles and neutropenia and/or infection in 13 cycles. CONCLUSIONS: Due to toxicity, a revised maximum tolerated dose for continuous infusion vinorelbine is proposed by the authors: 8 mg intravenously over 10 minutes followed by 10 mg/m(2) by continuous infusion over 24 hours every 4 days. The current dose schedule did not offer an advantage either in response rates or survival over the weekly vinorelbine bolus injection in doxorubicin-resistant and paclitaxel-resistant patients.

Adult↗
PubMed1999

Paclitaxel by 24-hour infusion with doxorubicin by 48-hour infusion as initial therapy for metastatic breast cancer: phase I results.

PURPOSE: We and others have demonstrated the antineoplastic efficacy of paclitaxel as a single agent in metastatic breast cancer. We performed this phase I trial to evaluate the combination of paclitaxel with doxorubicin. PATIENTS AND METHODS: Eligible patients had measurable or evaluable metastatic breast cancer for which this was the initial cytotoxic treatment. They may have received adjuvant chemotherapy with other drugs. The study had four parts. In part 1, the patients received paclitaxel by 24-hour infusion followed by doxorubicin by 48-hour infusion. The paclitaxel dose was to be escalated from a starting dose of 125 mg/m2, and the doxorubicin dose was to remain constant at 60 mg/m2 with treatment repeated every three weeks. The results of part 1 prompted part 2 which was a study of the reverse sequence. Part 3 was a formal study of pharmacology and has been reported (J Clin Oncol 14: 2713-21, 1996). In part 4, patients received doxorubicin 50 mg/m2 by bolus followed by paclitaxel 150 mg/m2 by 24-hour infusion for courses 1 and 2. In all subsequent courses doxorubicin was administered by 48-hour infusion. All patients in all four parts of the study had baseline cardiac scans. All patients received standard premedication for paclitaxel. RESULTS: Forty-eight patients were treated in all four parts of the study. In part 1 (10 patients), the maximum tolerated dose (MTD) was paclitaxel 125 mg/m2/24 hours followed by doxorubicin 48 mg/m2/48 hours as defined by dose-limiting mucositis and neutropenic fever which occurred at the starting dose. For part 2 (21 patients), the MTD was doxorubicin 60 mg/m2/48 hours followed by paclitaxel 160 mg/m2/24 hours. In part 4 (seven patients), the MTD was doxorubicin 50 mg/m2/bolus followed by paclitaxel 135 mg/m2/24 hours. In parts 2 and 4, the dose-limiting toxic effect was neutropenia. Of the entire cohort of 48 patients, seven (15%) had a complete response (one persists at five years without intervening therapy), 26 (54%) had a partial response for an objective response rate of 69% (95% confidence interval (95% CI): 54%-81%). The median follow-up of all living patients is 38+ months (range 20+ to 62+); the median response duration is seven months (range 2-33.7+); the median overall survival is 20.5 months (range 5-54+). The median time to progression is 9.6 months (range 1-33.7+ months). Two patients developed congestive heart failure, one at 24 months after her final dose of doxorubicin which amounted to a cumulative lifetime total doxorubicin dose of 870 mg/m2, one after a total of 660 mg/m2. In both, cardiac symptoms were controlled with medications. CONCLUSIONS: The combination of paclitaxel/24 hours with doxorubicin/48 hours is an effective antineoplastic treatment for metastatic breast cancer. However, the incidence of complete response, the median overall survival, and time to progression were not greater than for standard doxorubicin-based combinations. Additionally, a sequence-dependent interaction between paclitaxel and doxorubicin, given in the schedule described here, was defined. Other strategies and schedules should be evaluated to maximize the antineoplastic efficacy of these two potent agents.

Adult↗
PubMed1999

Phase II trial of liposome-encapsulated doxorubicin, cyclophosphamide, and fluorouracil as first-line therapy in patients with metastatic breast cancer.

PURPOSE: To determine the efficacy and safety profile, including the risk for cardiac toxicity, of liposome-encapsulated doxorubicin (TLC D-99), fluorouracil (5-FU), and cyclophosphamide as first-line chemotherapy in patients with metastatic breast cancer (MBC). PATIENTS AND METHODS: Forty-one women were registered in this phase II study. All patients had measurable disease and no previous chemotherapy for MBC. Treatment consisted of TLC D-99 60 mg/m2 and cyclophosphamide 500 mg/m2 on day 1 and 5-FU 500 mg/m2 on days 1 and 8 every 3 weeks. Serial cardiac monitoring, including endomyocardial biopsies, was performed. RESULTS: The overall response rate was 73% (95% confidence interval, 57% to 86%). The median duration of response was 11.2 months, the median time to treatment failure was 8.1 months, and the median overall survival duration was 19.4 months. The median number of cycles per patient was 10. The median cumulative dose of TLC D-99 was 528 mg/m2. Ten patients required hospitalization for febrile neutropenia. Nausea/vomiting, stomatitis, and fatigue higher than grade 2 occurred in 12%, 15%, and 41% of patients, respectively. Twenty-one patients reached a cumulative doxorubicin dose greater than 500 mg/m2. Three patients (7%) were withdrawn from the study due to protocol-defined cardiac toxicity, two because of a decrease in left ventricular ejection fraction to < or = 40%, and one because her endomyocardial biopsy result was grade 1.5. One patient had congestive heart failure that was probably nonanthracycline related. CONCLUSION: This chemotherapy regimen, including TLC D-99, was highly active against MBC and associated with low cardiac toxicity despite high cumulative doses of doxorubicin.

Adult↗
PubMed1998

Hand-foot syndrome following prolonged infusion of high doses of vinorelbine.

BACKGROUND: The authors reviewed the incidence of toxic skin reactions in patients with metastatic breast carcinoma (MBC) treated with vinorelbine as a continuous infusion. METHODS: A Phase I/II protocol was designed in which vinorelbine was given as an 8-mg intravenous bolus followed by a 96-hour CI of 7-14 mg/m2/day. Sixty patients were enrolled in the study: all had MBC and had received prior chemotherapy, and they had no known dermatologic disorder. RESULTS: Hand-foot syndrome (HFS) developed in 4 of the 60 patients. Patient 1 started with vinorelbine at 12 mg/m2/day. She developed typical HFS. In the second course, her dose was decreased to 11 mg/m2/day, but again she experienced HFS. In the third course, dexamethasone was added to the regimen, and no HFS was observed in the remaining six courses. Patient 2 started with a dose of 9 mg/m2/ day. She received four courses without complications; but when the vinorelbine dose was escalated to 10 mg/m2/day, HFS developed. Patient 3 started with a vinorelbine dose of 14 mg/m2/day. She developed mucositis during the first two courses and HFS during the third. Patient 4 received vinorelbine at a dose of 13 mg/m2/day and developed significant HFS. All patients had complete dermatologic recovery. No toxic skin reactions were observed in 14 patients receiving vinorelbine doses of <10 mg/m2/day, whereas 4 of 46 treated at 10-14 mg/m2/day developed HFS, suggesting a relationship of dose to HFS occurrence. CONCLUSIONS: Longer infusions of vinorelbine are occasionally associated with HFS. The pathophysiology is not completely clear, but a relationship of HFS occurrence to dose is suggested. Steroids were effective as prophylaxis in one patient.

Adult↗
PubMed1997

Prospective assessment of cardiac toxicity during a randomized phase II trial of doxorubicin and paclitaxel in metastatic breast cancer.

Since both doxorubicin and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) have substantial antitumor activity in advanced breast cancer, the combination of these two agents was a logical extension of the clinical development of paclitaxel. Early attempts used long infusions of both drugs, limiting the dose of both agents because of limiting gastrointestinal and myelosuppressive toxicity. Bolus doxorubicin combined with 3-hour infusion paclitaxel was reported to have dramatic antitumor activity, but clinically relevant cardiac toxicity in up to 20% of patients in two recent reports. In our current study the same schedules and doses of administration were used, limiting the total doxorubicin dose of 360 mg/m2. In-depth monitoring of cardiac function with noninvasive tests and endomyocardial biopsy were performed. Preliminary results suggest that, at these doses and schedule, the two-drug combination is safe, without unexpected toxicity. Limiting doxorubicin dose to 360 mg/m2 limits cardiac toxicity to levels expected from single-agent doxorubicin at similar cumulative doses.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Sequence-dependent alteration of doxorubicin pharmacokinetics by paclitaxel in a phase I study of paclitaxel and doxorubicin in patients with metastatic breast cancer.

PURPOSE: To determine whether a schedule-dependent interaction occurs when paclitaxel and doxorubicin are administered sequentially. PATIENTS AND METHODS: Ten patients with metastatic breast cancer received paclitaxel 125 mg/m2 over 24 hours either immediately before or after doxorubicin 48 mg/m2 over 48 hours as the initial chemotherapy treatment. Two such courses were given, and the sequence of administration was reversed after course 1. In cohort 1, paclitaxel preceded doxorubicin for course 1. In cohort 2, doxorubicin preceded paclitaxel for course 1. Doxorubicin levels were measured serially during the infusion and for 24 hours following it. Patients were assessed clinically for the occurrence of stomatitis and infection and granulocyte counts were measured twice weekly. RESULTS: Eight patients had complete pharmacokinetic sampling for both courses. The mean end-of-infusion plasma doxorubicin concentrations (Cmax) were 70% higher in the paclitaxel-doxorubicin sequence compared with the reverse sequence (45 +/- 8 ng/mL v 26 +/- 5 ng/ mL). The mean doxorubicin clearance was 32% lower in the paclitaxel-doxorubicin sequence (34.3 +/- 10.3 L/h v 51.6 +/- 16.1 L/h, P < .01). Clinically, hematologic and mucosal toxic effects were worse in the paclitaxel-doxorubicin sequence. The median absolute granulocyte count was 0.2/microL in the paclitaxel-doxorubicin sequence and 1.3/microL in the doxorubicin-paclitaxel sequence. Seven of 10 patients who received the paclitaxel-doxorubicin sequence had grade 2 (n = 4) or 3 (n = 3) stomatitis, while only one of 10 patients who received the doxorubicin-paclitaxel sequence had grade 2 stomatitis and none had grade 3. CONCLUSION: When paclitaxel by 24-hour infusion precedes doxorubicin by 48-hour infusion, doxorubicin clearance is reduced by nearly one third, which results in grade 2 and 3 stomatitis. To prevent this effect when paclitaxel (by 24-hour infusion) and doxorubicin are administered sequentially, doxorubicin should be given first. The mechanisms for this effect are under investigation.

Adult↗
PubMed1993

Multiple extracellular signals govern the production of a morphogenetic protein involved in aerial mycelium formation by Streptomyces coelicolor.

The formation of an aerial mycelium by the filamentous bacterium Streptomyces coelicolor is determined in part by a small morphogenetic protein called SapB. A collection of representative bald (bld) mutants, which are blocked in aerial mycelium formation, are all defective in the production of this protein and regain the capacity to undergo morphological differentiation when SapB is supplied exogenously. We now report that most of the bld mutants are rescued for SapB production and aerial mycelium formation when grown near certain other bld mutants. Extracellular complementation experiments of this kind indicate that morphological differentiation is governed by a hierarchical cascade of at least four kinds of intercellular signals. At least one such signal is present in conditioned medium. It is resistant to boiling and protease treatment, and it remains effective even when diluted up to eightfold in fresh medium.

Adult↗
PubMed1991

Extracellular complementation of a developmental mutation implicates a small sporulation protein in aerial mycelium formation by S. coelicolor.

The filamentous bacterium S. coelicolor differentiates by forming aerial hyphae, which protrude into the air and metamorphose into chains of spores. Aerial hyphae formation is associated with the production of a small, abundant protein, SapB, which is present in a zone around colonies of differentiating bacteria. Production of SapB is impaired in bld mutants, which are blocked in aerial hyphae formation, but not in whi mutants in which spore formation is prevented. We report that aerial hyphae formation by a newly identified bld mutant is restored by juxtaposition of the mutant near colonies of SapB-producing bacteria or by the application of the purified protein near mutant colonies. These observations implicate SapB in aerial mycelium formation and suggest that SapB is a morphogenetic protein that enables hyphae on the surface of colonies to grow into the air.

Bacterial Proteins↗
PubMed1991

Detection of direct mutagenicity of cigarette smoke condensate in mammalian cells.

Mutagenicity of cigarette smoke condensate (CSC) and the acidic, basic and neutral fractions of CSC was examined in the AL hybrid cell, a Chinese hamster ovary cell containing one human chromosome 11. Since the human chromosome 11 is not necessary for survival of the AL cells, mutations involving large deletions and chromosomal loss by non-dysjunction are non-lethal events that are detectable by loss of human cell surface antigens (a1, a2 and a3) encoded by genes on chromosome 11p (a1 and a3) and 11q (a2) through an antibody-complement lysis assay. Exposure of AL cells to CSC without exogenous metabolic activation caused a dose-dependent cytotoxicity and mutagenicity. Mutagenicity also increased with time of incubation up to 3 h with a maximum of 300 a1- mutants/10(5) survivors (250% above background; P less than 0.0005) after incubation with 100 micrograms/ml CSC. Cytotoxicity and mutagenicity of CSC were inversely proportional to cell density. Fifty percent lethal doses for the acidic, basic and neutral fractions of CSC after 3 h of incubation were 30, 100 and 240 micrograms/ml respectively, and the acidic fraction at a concentration of 25 micrograms/ml induced 350 a1- mutants/10(5) survivors (230% above background; P less than 0.0005); the basic and neutral fractions were less mutagenic. These results indicate that CSC and fractions of CSC can directly produce a spectrum of mutations, through both deletional and non-dysjunctional mechanisms of a kind known to lead to inactivation of tumor suppressor genes.

Animals↗
PubMed1991

Rapid electrochemiluminescence assays of polymerase chain reaction products.

We demonstrate the first use of an electrochemiluminescent (ECL) label, [4-(N-succimidyloxycarbonylpropyl)-4'-methyl-2,2'- bipyridine]ruthenium(II) dihexafluorophosphate (Origen label; IGEN Inc.), in DNA probe assays. This label allows rapid (less than 25 min) quantification and detection of polymerase chain reaction (PCR)-amplified products from oncogenes, viruses, and cloned genes. For the PCR, we used labeled oligonucleotide primers complementary to human papiloma virus and the Ha-ras oncogene. These samples were followed by ECL analysis or hybridization with specific, Origen-labeled oligonucleotide probes. These studies demonstrate the speed, specificity, and effectiveness of the new ECL labels, compared with 32P, for nucleic acid probe applications. We describe formats involving conventional methodologies and a new format that requires no wash step, allowing simple and rapid sample analysis. These rapid assays also reduce PCR contamination, by requiring less sample handling. Improvements in ECL detectability are currently under investigation for use in DNA probe assays without amplification.

2,2'-Dipyridyl↗