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Biomedical subjects

T Griffin

Publications and source records attributed to T Griffin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Preliminary studies of a novel oral fluoropyrimidine carbamate: capecitabine.

PURPOSE: To evaluate the toxicology and pharmacology of an orally active fluoropyrimidine given as a continuous daily dose divided into two portions for 6 weeks, and to determine the maximal-tolerated daily dose (MTD) and the suggested phase II daily dose. PATIENTS AND METHODS: Solid-tumor patients with a Karnofsky performance status greater than 70 who had normal organ function and resolution of the effects of prior therapy, and who gave informed written consent, were enrolled. Oral capecitabine, as a divided morning and evening dose, was administered to cohorts of a minimum of 3 patients starting at 110 mg/m2 and escalating by means of a modified Fibonacci scheme to 1,657 mg/m2/d. Pharmacologic samples were obtained on days 1 and 15. Toxicity evaluations were performed approximately every 3 days for the first 43 days. Antitumor effect was evaluated at day 42 of therapy. RESULTS: Thirty-three patients entered the study. Few side effects occurred at or below 1,331 mg/m2/d. The MTD was 1,657 mg/m2/d with limiting toxicities of palmar-plantar erythrodysesthesia, nausea, vomiting, vertigo, abdominal pain, diarrhea, and thrombocytopenia. All toxicities were reversible. A mixed response was seen in one breast cancer patient. Pharmacologic studies showed rapid and extensive metabolism of the parent drug into cytotoxic metabolites with a maximum plasma concentration (Cmax) 1 hour after ingestion. Linear increases in the area under the concentration-time curve (AUC) and Cmax were seen with linear increases in administered dose. CONCLUSION: The suggested phase II dose on a continuous 42-day dosing schedule is 1,331 mg/m2/d. Linear pharmacologic parameters of the parent compound and metabolites are demonstrated.

Administration, Oral↗
PubMed1998

Phase I and pharmacologic study of intermittent twice-daily oral therapy with capecitabine in patients with advanced and/or metastatic cancer.

PURPOSE: Capecitabine is an orally administered fluoropyrimidine carbamate selectively activated to fluorouracil (5-FU) in tumors. It passes through the intestinal mucosal membrane intact and is subsequently activated by a cascade of three enzymes that results in the preferential release of 5-FU at the tumor site. PATIENTS AND METHODS: In this phase I study, capecitabine was administered twice daily as outpatient therapy, each cycle administered for 2 weeks followed by 1 week of rest. Thirty-four patients with solid tumors, all of whom except three patients were pretreated, were treated at dose levels from 502 to 3,514 mg/m2 daily. RESULTS: The median treatment duration was four cycles (85 days; range, 14 to 833+ days). Two patients continue on treatment at 686 and 833+ days. Capecitabine 3,000 mg/m2 daily was not tolerable, with dose-limiting toxicities of diarrhea with hypotension, abdominal pain, and leukopenia. Palmar-plantar erythrodysesthesia (PPE) became evident at higher dose levels after prolonged treatment. Evidence of objective tumor response was reported in four patients at 2,510 mg/m2 daily and greater (one complete response [CR] and three partial responses [PRs]) with subjective minor tumor responses in a further seven patients. Pharmacokinetic studies showed rapid gastrointestinal absorption of capecitabine, followed by extensive conversion into 5'-deoxy-5-fluorouridine (5'-DFUR), with only low systemic 5-FU levels. CONCLUSION: Capecitabine is a tolerable oral outpatient therapy that shows promising clinical activity in a variety of cancers. The recommended phase II dose is 2,510 mg/m2 daily administered by this intermittent schedule.

Administration, Oral↗
PubMed1998

A Phase I study of capecitabine in combination with oral leucovorin in patients with intractable solid tumors.

Capecitabine (Xeloda) is a novel rationally designed fluoropyrimidine carbamate. It passes through the intestinal mucosal membrane intact and is subsequently activated by a cascade of three enzymes resulting in preferential release of 5-fluorouracil (5-FU) at the tumor site. Preclinical studies indicated an enhancement of the therapeutic index when capecitabine was combined with leucovorin. This Phase I trial was designed to determine the safety profile, maximal tolerated dose, and pharmacokinetic profile of the combination of capecitabine plus a fixed dose of p.o. leucovorin (60 mg/day) during administration to patients with refractory advanced cancers. The intention was to administer both drugs continuously, but the starting dose of capecitabine was also the maximum tolerated dose (1004 mg/m2/day) in six patients treated with this regimen. A cycle of treatment was then redefined as leucovorin and capecitabine given p.o., twice daily for 2 consecutive weeks followed by a 1-week rest period. Capecitabine doses from 1004 mg/m2/day to 2510 mg/m2/day were evaluated with the intermittent schedule over approximately 80 courses in an additional 25 patients. The dose-limiting toxicities that defined the maximum tolerated dose at 2000 mg/m2/day were diarrhea, nausea, vomiting, and palmar plantar erythrodysesthesia. The recommended Phase II dose using this schedule was 1650 mg/m2/day of capecitabine plus leucovorin 60 mg/day. Plasma concentrations of capecitabine, intermediate metabolites, and 5-FU were measured in 26 patients on days 1 and 14 of therapy. The pharmacokinetics of capecitabine were characterized by rapid GI absorption, with Cmax at 1 h, followed by conversion to active drug. The coadministration of leucovorin had no effect on the pharmacokinetics of capecitabine. Two patients with colorectal cancer, both previously treated with 5-FU, had partial responses. Phase II studies have confirmed the promising antitumor activity of this drug, and capecitabine is currently in Phase III evaluation.

Administration, Oral↗
PubMed1997

Automated planning target volume generation: an evaluation pitting a computer-based tool against human experts.

PURPOSE: Software tools are seeing increased use in three-dimensional treatment planning. However, the development of these tools frequently omits careful evaluation before placing them in clinical use. This study demonstrates the application of a rigorous evaluation methodology using blinded peer review to an automated software tool that produces ICRU-50 planning target volumes (PTVs). METHODS AND MATERIALS: Seven physicians from three different institutions involved in three-dimensional treatment planning participated in the evaluation. Four physicians drew partial PTVs on nine test cases, consisting of four nasopharynx and five lung primaries. Using the same information provided to the human experts, the computer tool generated PTVs for comparison. The remaining three physicians, designated evaluators, individually reviewed the PTVs for acceptability. To exclude bias, the evaluators were blinded to the source (human or computer) of the PTVs they reviewed. Their scorings of the PTVs were statistically examined to determine if the computer tool performed as well as the human experts. RESULTS: The computer tool was as successful as the human experts in generating PTVs. Failures were primarily attributable to insufficient margins around the clinical target volume and to encroachment upon critical structures. In a qualitative analysis, the human and computer experts displayed similar types and distributions of errors. CONCLUSIONS: Rigorous evaluation of computer-based radiotherapy tools requires comparison to current practice and can reveal areas for improvement before the tool enters clinical practice.

Expert Systems↗
PubMed1997

Biospecific affinity chromatographic purification of octopine dehydrogenase from molluscs.

The development of a biospecific affinity chromatographic method for the purification of octopine dehydrogenase from molluscs is described. The method utilizes immobilized NAD+ derivatives in conjunction with soluble specific substrates to promote binding. Using this method, octopine dehydrogenase has been purified to electrophoretic homogeneity in a single chromatographic step from three different marine invertebrate sources [the queen scallop, Chlamys opercularis (adductor muscle), the great scallop, Pecten maximus (adductor muscle), and the squid Loligo vulgaris (mantle muscle)]. However, the system is not applicable to the purification of octopine dehydrogenase from some other marine invertebrate sources investigated (the mussel Mytilus edulis and the topshell Monodonta lineata).

Adenosine Monophosphate↗
PubMed1997

An overview of the population in Europe and North America.

This article is based on information from Trends in Europe, the statistical yearbook of the Economic Commission for Europe. It highlights some of the key population and health statistics for member countries, using the most recent data available--generally for 1995--collected from a wide range of national and international sources.

Adolescent↗
PubMed1996

Further studies on the bioaffinity chromatography of NAD(+)-dependent dehydrogenases using the locking-on effect.

Previous studies have capitalized on ordered kinetic mechanisms in the design of biospecific affinity chromatographic methods for highly efficient purifications and mechanistic studies of enzymes. The most direct tactic has been the use of immobilised analogues of the following, usually enzyme-specific substrates, e.g., lactate/pyruvate in the case of lactate dehydrogenase for which NAD+ is the leading substrate. Such immobilised specific substrates are, however, often difficult or impossible to synthesise. The locking-on strategy reverses the tactic by using the more accessible immobilised leading substrate, immobilised NAD+, as adsorbent with soluble analogues of the enzyme-specific ligands (e.g., lactate in the case of lactate dehydrogenase) providing a substantial reinforcement of biospecific adsorption sufficient to effect adsorptive selection of an enzyme from a group of enzymes such as the NAD(+)-specific enzymes. The value of this approach is demonstrated using model studies with lactate dehydrogenase (LDH, EC 1.1.1.27), alcohol dehydrogenase (ADH, EC 1.1.1.1), glutamate dehydrogenase (GDH, EC 1.4.1.3) and malate dehydrogenase (MDH, EC 1.1.1.37). Purification of bovine liver GDH in high yield from crude extracts is described using the tactic.

Affinity Labels↗
PubMed1996

Pityriasis rubra pilaris with acantholysis.

Two patients developed a papulosquamous eruption in a widespread distribution which progressed with islands of sparing of uninvolved skin characteristic clinically of adult-onset pityriasis rubra pilaris (PRP). Biopsies from both patients showed multiple areas of nonfollicular and follicular suprabasilar and intra-epidermal acantholysis with minimal dyskeratosis. They also showed the usual histologic features of PRP with a thickened orthokeratosis and parakeratosis, a retained and sometimes thickened granular cell layer, and psoriasiform epidermal hyperplasia with a perivascular lymphohistiocytic infiltrate in the superficial dermis. Two previous patients with PRP have been reported with nonfollicular, focal acantholytic dyskeratosis and both were interpreted as most likely representing an incidental finding. We believe the acantholysis in these two cases is related to the disease process, and in our second patient, was helpful in establishing the diagnosis.

Acantholysis↗
PubMed1996

Improved survival for children with B-cell acute lymphoblastic leukemia and stage IV small noncleaved-cell lymphoma: a pediatric oncology group study.

PURPOSE: In an effort to improve outcome for children with advanced B-cell malignancies, a treatment plan based on a published regimen that consists of four courses of fractionated cyclophosphamide (cyclo) given with doxorubicin (doxo) and vincristine (VCR) was intensified by alternating with sequential high-dose methotrexate (MTX) and cytarabine (Ara-C), given in conjunction with intrathecal (IT) MTX and Ara-C. PATIENTS AND METHODS: From October 1986 to October 1992, 133 eligible patients were enrolled: 74 with B-cell (surface immunoglobulin-positive [Slg+] acute lymphoblastic leukemia (B-ALL) and 59 with stage IV small noncleaved-cell lymphoma (SNCCL). The median age was 8 years; there were 103 males and 30 females. Abdominal tumor masses were prominent in 63 cases (33 B-ALL and 30 stage IV SNCCL). RESULTS: Complete remission (CR) was achieved in 66 B-ALL and 57 stage IV patients (93% overall). At 4 years, the estimated event-free survival (EFS) rate is 65% +/- 8% for patients with B-ALL and 79% +/- 9% for those with stage IV SNCCL. Among patients with CNS involvement, 23 of 36 remain in CR (4-year EFS rate, 64% +/- 13%). Relapses occurred early; only 3 patients relapsed after completion of therapy. Thirteen relapses occurred in the marrow, three in the CNS, and six in other sites. Of 11 CNS-positive patients who relapsed, only two recurred primarily in the CNS. CONCLUSION: The results of this study indicate that with intensified chemotherapy an increasing potential for cure exists for patients with B-ALL and stage IV SNCCL.

Adolescent↗
PubMed1996

Phase I trial of 9-cis retinoic acid in adults with solid tumors.

Retinoids have been shown to be potent inhibitors of epithelial carcinogenesis. Recent evidence has demonstrated that retinoid actions are mediated through nuclear receptors, which are proteins encoded by the retinoic acid receptor and retinoid X receptor gene families. These receptors are activated by binding to specific retinoids; of the known naturally occurring retinoids, 9-cis retinoic acid is unique in its ability to bind to both receptor families. Because of its unique receptor-binding characteristics, 9-cis retinoic acid may have biological activity not possible with other retinoids. For this reason, we conducted a Phase I trial of 9-cis retinoic acid in adult patients with solid tumors. Twenty-two patients were treated twice daily with p.o. 9-cis retinoic acid at doses ranging from 20 mg/m2/day to 150 mg/m2/day. The patients had non-small cell lung cancer (n = 8), breast cancer (n = 5), colorectal cancer (n = 3), head and neck cancer (n = 2), nonmelanoma skin cancer (n = 2), or ovarian cancer (n = 2). The dose-limiting (WHO grade III) toxic effects, which occurred at the 150-mg/m2/day dose level, were headaches and diarrhea. Less severe (grades I and II) toxic effects included cheilitis, dry skin, conjunctivitis, fatigue, hypertriglyceridemia, alkaline phosphatase elevation, myalgia/arthralgia, and hypercalcemia. Of the 15 patients evaluable for tumor response, no objective responses were observed. Pharmacokinetic analysis revealed a reduction in peak 9-cis retinoic acid plasma levels with chronic administration. Based on this study, the recommended Phase II dose of 9-cis retinoic acid in adult patients with solid tumors is 100 mg/m2/day administered in a divided dose twice daily.

Adult↗
PubMed1995

Perception of facial attractiveness by patients, peers, and professionals.

Self-perception of facial attractiveness of 19 women (15 with Class II malocclusion and four with Class I malocculsion) was compared to the perceptions of the patient's peers, five orthodontists, and five oral surgeons. Each respondent ranked a set of four standardized facial photographs of each patient from most (1) to least (19) attractive. A surgical treatment plan was recommended for all of the Class II patients. However, only nine accepted surgery; six elected to undergo camouflaging orthodontics only. There was a statistically significant difference in the distribution of ranks given to the Class I, Class II camouflage-only, and Class II surgery groups by the panels. Overall, the Class I patients were judged most attractive. The Class II patients who elected to undergo orthodontics only were given mid-ranks, and the patients who elected surgery were ranked least attractive, although the distributions for overjet, point A-nasion-point B, and motivations for treatment were similar in the two groups. The distribution of self-ranks given by the patients were not significantly different among the three groups, although than the Class II patients perceived themselves as less attractive than the Class I patients.

Adult↗
PubMed1994

Impact of a multileaf collimator on treatment morbidity in localized carcinoma of the prostate.

PURPOSE: To evaluate the effectiveness of variable multileaf collimation, three-dimensional treatment planning, and computer-controlled conformal radiation therapy of prostate cancer. METHODS AND MATERIALS: Two hundred and forty-five patients with locally advanced prostate cancer have completed treatment over a 9-year time span using a multileaf collimator and conformal treatment techniques on the University of Washington cyclotron. All patients had three-dimensional treatment planning with computed tomography scans in the treatment position, and had treatment fields individually shaped to the target volume with a continuously variable multileaf collimator. Treatment was delivered under computer control with network transfer of the multileaf collimator settings from the treatment planning computer to the cyclotron control system. RESULTS: The multileaf collimator combined with three-dimensional treatment planning results in elegant dose distributions. These neuron dose distributions resulted in a reduced local/regional tumor failure rate with no increase in complications when compared to control treatment with photons in a randomized trial. Neutron treatment delivered at other institutions without conformal beam shaping resulted in the same improvement in local-regional tumor control rates, but was associated with a significantly higher normal tissue complication rate than seen with conformal neutron beam delivery techniques (grade 3 and 4 cumulative late normal tissue toxicity rates of 39% vs. 10%, p = 0.0007). CONCLUSIONS: Conformal treatment of prostate cancer using a multileaf collimated neutron beam results in increased local/regional tumor control rates with low normal tissue toxicities. This experience is directly applicable to the conformal treatment of prostate cancer with photons.

Humans↗
PubMed1994

Potentiation of ricin A immunotoxin by monoclonal antibody targeted monensin containing small unilamellar vesicles.

The carboxylic ionophore monensin could be successfully entrapped in small unilamellar vesicles made by the extruder method. Monensin liposomes of size range 100-150 nm were more potent in potentiating ricin A immunotoxin activity in vitro as compared to monensin liposomes of diameter 500 nm or more. These liposomes were further successfully linked to tumor specific monoclonal antibodies with full retention of immunoreactivity. Monoclonal antibody targeted monensin liposomes were 100 times more potent than monensin liposomes in potentiating the activity of ricin A immunotoxins against various tumor cell lines in vitro.

Antibodies, Monoclonal↗
PubMed1993

Potentiation of antitumor immunotoxins by liposomal monensin.

BACKGROUND: The cytotoxicity of specific ricin A-chain immunotoxins is greatly enhanced in vitro by the carboxylic ionophore monensin. However, the highly lipophilic nature of monensin, which is reflected in its poor solubility and short half-life, has restricted its use in in vivo animal studies. PURPOSE: The purpose of this study was to assess the ability of monensin incorporated in unilamellar vesicles (liposomes) to potentiate antitumor immunotoxins in vitro and in vivo. METHODS: Monensin was incorporated into liposomes and used in combination with specific immunotoxins against human tumor cell lines in vitro and in vivo. Inhibition of [3H]leucine incorporation was used to evaluate the cytotoxic action of immunotoxin with or without monensin in vitro on the following human tumor cell lines: H-MESO-1 malignant mesothelioma, LS174T colorectal carcinoma, and U373, U87, and MG-1 glioblastomas. For the in vivo studies of immunotoxins and liposomal monensin, BALB/c nu/nu mice were inoculated intraperitoneally with H-MESO-1 cells. RESULTS: Liposomal monensin potentiated the cytotoxic action of cell-specific anti-human transferrin receptor immunotoxin on H-MESO-1 target cells at a molar concentration of monensin that was 160-fold lower than the concentration of monensin in buffer that produced the same effect (0.3 nM versus 0.05 microM). Moreover, immunotoxin plus 0.1 microM liposomal monensin was fivefold more toxic for H-MESO-1 cells and 1000-fold and 2200-fold more toxic for human glioblastoma U373 and U87 cells, respectively, than immunotoxin plus 0.1 microM free monensin in buffer. Liposomal monensin produced similar effects when it was combined with different specific immunotoxins and other target cell lines (i.e., LS174T, U87, and CEM). Immunotoxin specificity was preserved with liposomal monensin, as shown by the absence of effect with non-cell-binding immunotoxins or on antigen-negative cell lines. In mice, liposomal monensin in combination with specific immunotoxin substantially prolonged survival, and three (21%) of 14 mice bearing H-MESO-1 xenografts treated with the liposomes showed no evidence of tumor at day 160 after treatment. Treatment with control immunotoxin plus liposomal monensin was ineffective. CONCLUSION: These findings suggest that encapsulation of monensin into liposomes increased the capacity of monensin to enhance the potency of cell-specific immunotoxin in vitro and in vivo.

Adjuvants, Immunologic↗
PubMed1993

Comparing different types of performance feedback and computer-based instruction in teaching medical students how to diagnose acute abdominal pain.

PURPOSE: To examine the relative efficacies of three types of performance feedback used with computer-based instruction (CBI) in making diagnoses. METHOD: In 1990, 75 final-year medical students at The University of Queensland were pretested for domain knowledge and diagnostic skill in the area of acute abdominal pain. The students were also asked to indicate their confidence in each of their diagnoses. Following these pretests, the students were randomly divided into five groups of 15 students each. One group received traditional CBI, using a "question-and-explanation" format, to learn domain knowledge. The other four groups received one of two types of CBI to learn diagnostic accuracy, and these four groups received one of three types of performance feedback (which differed considerably in the amounts of information imparted). Then the students took posttests. One-way analysis of variance, Student's t-test, and the Tukey test were used to compare the performances of the different groups of students. RESULTS: Although the students in the traditional CBI group significantly improved their performance on multiple-choice questions (by 58%) compared with the other groups of students (6-10% improvement), these students did not improve their diagnostic performance. In contrast, the CBI groups that used simulated-patient cases and structured-performance feedback did improve their diagnostic accuracy (by as much as 16%, compared with a 1% decline for the traditional CBI group). Contrary to expectation, the different types of feedback were equally effective. Except for the students in the traditional CBI group, the students' confidence increased from pretest to posttest regardless of their performances. CONCLUSION: CBI that uses simulated-patient cases and structured-performance feedback seems to be efficient and effective compared with traditional CBI methods. However, care should be taken to ensure that students do not become overconfident of their abilities.

Abdominal Pain↗