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Biomedical subjects

S G Taylor

Publications and source records attributed to S G Taylor.

At least 91 records · Page 5Linked to original sources
PubMed1988

Pilot study of adriamycin and amsacrine (m-AMSA) in patients with advanced breast cancer.

Twelve patients with recurrent and metastatic breast cancer were treated with a combination of adriamycin and amsacrine (m-AMSA) to evaluate its efficacy and toxicity. Adriamycin was given at 40 mg/m2 i.v. and m-AMSA at 50 mg/m2 i.v. every 3 weeks. No response was observed. One patient received an escalated m-AMSA dose at 70 mg/m2 and the same dose of adriamycin. She died of treatment-related leukopenia and infection. We conclude that the combination of adriamycin and amsacrine at the dose and schedule used in our trial has little antitumor effect in the treatment of advanced breast cancer.

Adult↗
PubMed1988

ECOG phase II trials of MGBG, chlorozotocin, COM multidrug therapy in advanced measurable colorectal cancer.

The Eastern Cooperative Oncology Group (ECOG) entered 326 patients with advanced measurable colorectal cancer into four phase II drug or drug combination trials. Previously treated and chemotherapy-naive patients were eligible. Chlorozotocin was administered to 83 patients (51 previously treated), methyl-glyoxal-bis-guanylhydrozone (MGBG) to 90 patients (58 previously treated), and two regimens of the three-drug combination of cyclophosphamide, vincristine, and methotrexate (COM) to 153 patients (120 previously treated). The multidrug regimen had been developed specifically for previously treated patients. In this trial, chemotherapy-naive patients were no more likely to respond than were members of the previously-treated group. Even among previously untreated patients, response rates did not exceed 10% in any of these phase II programs. They are not recommended for further trials in patients with colorectal cancers.

Adenocarcinoma↗
PubMed1988

The mode of action of pinacidil and its analogs P1060 and P1368: results of studies in rat blood vessels.

In rat portal vein and aorta, pinacidil (0.3-100 microM) inhibited spontaneous mechanical activity (portal vein) and responses to norepinephrine (0.001-100 microM) and to KCl (5-80 mM). Pinacidil and its analogs P1060 and P1368 inhibited established contractions to 20 mM KCl but had little effect on responses to 80 mM KCl. The order of spasmolytic potency was P1060 greater than pinacdil greater than P1368. Intracellular electrical recording showed that in a portal vein, pinacidil (0.3-10 microM) abolished spontaneous electrical activity and hyperpolarised the cells to the region of the calculated EK. Pinacidil (3-10 microM) produced a similar hyperpolarisation in rat aorta, and in both tissues the hyperpolarisation was maintained in the continuing presence of pinacidil. Using 86Rb as a K+ marker, pinacidil increased 86Rb exchange in both the rat portal vein and aorta. The analog P1060 also increased 86Rb efflux in the rat portal vein; P1368 had no significant effect. It is concluded that the inhibitory effects of pinacidil in rat blood vessels are associated with the opening of 86Rb-permeable K+ channels. This mechanism produces a low-resistance pathway in the membrane and this inhibits the ability of pressor agents to produce smooth muscle contraction.

Animals↗
PubMed1988

Endothelium-dependent effects of acetylcholine in rat aorta: a comparison with sodium nitroprusside and cromakalim.

1. The mechanisms involved in the mechano-inhibitory effects of acetylcholine (ACh) have been compared with those of sodium nitroprusside (SNP) and cromakalim on the rat isolated thoracic aorta. 2. Relaxations produced by ACh were endothelium-dependent, whereas those produced by SNP or cromakalim were endothelium-independent. 3. ACh, cromakalim and SNP relaxed established contractions produced by noradrenaline (NA) and KCl (20 mM) and these relaxations were well-maintained. 4. SNP was a relatively effective inhibitor of contractions produced by KCl (80 mM). ACh was relatively ineffective and cromakalim was without effect against such contractions. 5. Membrane potential and cyclic GMP concentrations were higher in tissues with an intact endothelium whereas rubbed tissues had a higher 86Rb efflux rate coefficient. 6. ACh and cromakalim produced a transient and long-lasting hyperpolarization, respectively. These changes were accompanied by increases in the 86Rb efflux rate coefficient with a time course comparable to that of the electrical changes. 7. Tissue cyclic GMP concentrations were significantly increased in the presence of ACh or SNP, whereas cromakalim had no effect. 8. Transmission electron microscopy showed the presence of endothelial cells on intact tissues. On rubbed preparations, such cells were absent and some damage to the underlying smooth muscle cells was detected. 9. It is concluded that at least two inhibitory substances are released from the endothelial cells by ACh. One of these increases tissue cyclic GMP concentrations and produces an electrically-silent relaxation. The other produces a transient hyperpolarization associated with the opening of 86Rb-permeable K-channels. This event may serve to initiate relaxation processes and to close any open voltage-dependent Ca-channels.

Acetylcholine↗
PubMed1988

Evaluation of the potassium channel activator cromakalim (BRL 34915) as a bronchodilator in the guinea-pig: comparison with nifedipine.

1. The potential of the potassium channel activator, cromakalim (BRL 34915), as a bronchodilator has been evaluated in guinea-pig models in comparison with nifedipine. Some effects of the compounds on guinea-pig tracheal spirals have been studied in an attempt to elucidate their different efficacies in vivo. 2. When given by the intraduodenal route to anaesthetized guinea-pigs, cromakalim (3 and 10 mg kg-1) inhibited 5-hydroxytryptamine (5-HT)-induced bronchospasm for at least 60 min. When given by the i.v. route, the dose of cromakalim producing 50% inhibition of the 5-HT response was 84 micrograms kg-1. Nifedipine failed to show any protective effect up to 100 micrograms kg-1, i.v. and was lethal at higher dose levels. 3. Cromakalim protected conscious guinea-pigs from asphyxic collapse in response to histamine aerosol. The maximal effect occurred 60 min following oral dosing, with 2.5 mg kg-1 providing complete protection for almost half of the animals. Nifedipine had only a weak protective effect even at a high dose level of 50 mg kg-1, p.o. 4. Cromakalim prolonged the time before convulsive cough in response to an antigen challenge in actively sensitized guinea-pigs. Its minimum protective dose was 1 mg kg-1, p.o. Nifedipine (50 mg kg-1, p.o.) was ineffective. 5. Cromakalim inhibited both spontaneous and prostaglandin E2-induced tone in guinea-pig isolated tracheal spirals with IC50 values, relative to the maximum inhibition achieved by isoprenaline (10(-3)M), of 1.1 x 10(-6)M and 8.9 x 10(-7)M, respectively. Its maximal effect was 89% of that produced by isoprenaline. Removal of the epithelium did not influence its activity. Studies using the two enantiomers showed that the activity of cromakalim resided almost entirely in the (-)-enantiomer. 6. Nifedipine (2 x 10-SM) achieved only 49% of the relaxant effect of 10 -3M isoprenaline in isolated tracheal spirals. Addition of cromakalim (10- 5 M) at the end of the nifedipine concentrationresponse experiment caused further relaxation to 94% of the effect of isoprenaline. 7. It is concluded that cromakalim has greater potential than nifedipine as a bronchodilator. It appears that opening of potassium channels, with consequent hyperpolarization and stabilization of the membrane potential, prevents calcium entering the cytosol through routes that are unaffected by calcium entry blockers.

Animals↗
PubMed1988

Continuous infusion of etoposide, bolus administration of cisplatin, and simultaneous radiation therapy in previously treated patients with small cell bronchogenic carcinoma.

Thirty-one patients with previously treated small cell bronchogenic carcinoma were treated with split-course radiation therapy and concurrent cisplatin and etoposide. Twenty-four patients (78%) had clinical partial or complete responses. Median survival from the time of salvage was 6.3 months. Fifty-eight percent of the patients failed on therapy initially in sites outside the radiation port. Hematologic toxicity was moderate. Concurrent cisplatin, etoposide, and split-course radiation therapy is feasible and active in the treatment of small cell bronchogenic carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Concomitant therapy with infusion of cisplatin and 5-fluorouracil plus radiation in stage III non-small cell lung cancer.

Based on our experience with head and neck cancer, we have developed an every-other-week, split-course schedule for giving combined cisplatin and 5-fluorouracil infusion and radiation to patients with regionally advanced non-small cell lung cancer for a limited number of cycles prior to planned resection. Sixty-four patients having stage III disease without distant metastases were treated with 4 cycles of combined chemotherapy and radiation to 40 Gy and were offered surgical resection. Thirty-nine patients (61%) underwent surgery. Nine had no residual cancer. No correlation was noted between clinical and histologic responses in the surgery group, but histologic response correlated with subsequent outcome. Survival was 58% at 1 year, 33% at 2 years, and 22% at 3 years. Although encouraging, the overall dismal prognosis of this disease has led us to pursue further improvements in protocol design prior to phase III testing of this concept. To this end, etoposide has been added to the above regimen, extending the cycles from every other week to every third week.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Phase II trial of therapy with etoposide, 5-fluorouracil by continuous infusion, cisplatin, and simultaneous split-course radiation in stage III non-small cell bronchogenic carcinoma.

Survival of patients who have clinical stage IIIM0 non-small cell bronchogenic carcinoma remains relatively short despite treatment with either surgery or radiation. Results from a phase II study of simultaneous continuous infusion of 5-fluorouracil, cisplatin, and split-course radiation with or without surgery indicate that median survival duration in patients treated with this combined modality approach may be better than the median survival for patients treated with radiation alone. Etoposide has been added to this regimen, and 32 stage IIIM0 non-small cell lung cancer patients have been treated with the 3-drug regimen resulting in a 73% clinical partial remission rate. No residual tumor was found in 6 of 12 patients who had pulmonary resection after 4 courses of chemotherapy and radiation. The sites of failure in 8 patients with recurrent disease are as follows: local only, 3; distant only, 4; and local and distant, 1. The major toxicities have been leukopenia, nausea, and vomiting. The median leukocyte nadir was 2,400/mm3. A leukocyte count less than 1,000/mm3 was observed in 2 patients (7%), 1 of whom died of progressive pneumonia. All patients experienced nausea, vomiting, and anorexia. Severe esophagitis, dermatitis, and pneumonitis were not observed. Survival analysis has not been done because median follow-up time (326 days) is relatively short.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Concomitant therapy with infusion of cisplatin and 5-fluorouracil plus radiation in head and neck cancer.

We have combined cisplatin, 5-fluorouracil infusion, and radiation in an every-other-week schedule in a phase I-II study of 44 patients with head and neck cancer to assess toxicity and response. Ten patients were treated palliatively with 2 to 6 cycles of therapy, and 34 were treated curatively with a planned 7 cycles. Of 34 patients treated curatively, all were initially controlled. Three died during treatment (1 myocardial infarction, 1 bowel perforation, and 1 renal failure after amino-glycoside antibiotics). Four patients have had regional recurrences, 7 failed at distant sites (follow-up 2 to 5 yr). Thirty-three percent of 20 patients with complete clinical disappearance of all evidence of their cancer have had a recurrence, as have 38% of 14 (P greater than .1) with some residual abnormalities (partial responders) following treatment. All failures were in the 25 patients with T4 and/or N3 disease. None of the 9 patients with lesser stage IV or stage III disease who were followed for 24 months or more had recurrences. Eighteen patients (53%) survive with a projected 3-year survival of 63% (95% confidence interval 47% to 77%). Nine (27%) have died of disease, 1 (3%) died of a second primary in the head and neck, 3 (9%) of intercurrent disease at 15 to 45 months, and 3 (9%) during treatment. Of the 10 patients treated palliatively, 1 died during treatment with hepatic failure, 6 had complete responses, and 2 had partial responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Treatment of advanced head and neck cancer with concomitant radiation and chemotherapy.

Forty-four patients with predominantly inoperable or recurrent head and neck cancers were treated with combined chemotherapy (CT) and radiation therapy (RT) in a Phase I/II study. CT and RT were combined in a concomitant fashion to take advantage of radiosensitizing properties of the chemotherapeutic agents. Each treatment cycle consisted of cisplatin 60 mg/M2 on day 1, 5-FU infusion at a dose of 800 mg/M2 per day continuously for 5 days and RT at 200 cGy per day, days 1 through 5. The treatment cycle was repeated every 2 weeks for 7 cycles in patients treated curatively and for 2 to 6 cycles in patients treated palliatively due to prior radiation therapy or the presence of metastatic disease. Regional control was achieved in 98% of the patients. Regional control has persisted in 87% of the patients treated curatively with a minimum follow-up of 24 months. Distant failure occurred in 23% of this group. Actuarial survival of 2 years for the curative group is 66%. Concomitant combination of radiation with radiation potentiating chemotherapeutic agents shows promise of increase in local control.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Simultaneous cisplatin fluorouracil infusion and radiation followed by surgical resection in regionally localized stage III, non-small cell lung cancer.

Sixty-four patients with stage III (M omicron) non-small cell lung cancer were treated with cisplatin fluorouracil infusion chemotherapy and simultaneous radiation therapy for 5 days every other week. A total of 4 cycles (40 Gy) was followed by attempted surgical resection. Clinical response to the preoperative treatment included 5 (8%) complete and 32 (48%) partial responses. Thirty-nine (61%) underwent the planned operation, and in 9 (23%) of these patients the resected specimens were histologically negative. Clinical assessment failed to predict histological response. With 17 months median follow-up (range, 2.4-29 months), estimated 1-year survival was 61% and median survival was 16 months for all patients.

Adult↗
PubMed1987

Evidence that the mechanism of the inhibitory action of pinacidil in rat and guinea-pig smooth muscle differs from that of glyceryl trinitrate.

The effects of pinacidil have been compared with those of glyceryl trinitrate (GTN) using the aorta and portal vein of the rat and the trachealis and taenia caeci of the guinea-pig. In aorta, both pinacidil and GTN inhibited responses to noradrenaline and showed some selective inhibition of contractions to 20 mM K+. Responses to 80 mM K+ were little affected. In trachealis, both pinacidil and GTN inhibited spontaneous tone and selectively relaxed spasms to 20 mM K+. Responses to 80 mM K+ were unaffected. In portal vein, pinacidil completely inhibited spontaneous electrical and mechanical activity. GTN reduced the amplitude of tension waves and extracellularly-recorded discharges, but increased the frequency of spontaneous electrical and mechanical activity. In portal vein, pinacidil inhibited contractions to noradrenaline and selectively inhibited responses to 20 mM K+. GTN had little inhibitory effect on responses to either noradrenaline or K+. In portal veins loaded with 86Rb as a K+-marker, pinacidil significantly increased the 86Rb efflux rate coefficient whilst GTN had no effect on 86Rb exchange. In taenia caeci, both pinacidil and GTN inhibited the spontaneous tone of the preparation. These inhibitory effects were not antagonized by apamin. It is concluded that pinacidil and GTN do not share a common relaxant mechanism. Evidence has been obtained that pinacidil exerts its inhibitory effects by the opening of apamin-insensitive, 86Rb-permeable K+ channels.

Animals↗