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Biomedical subjects

R L Stephens

Publications and source records attributed to R L Stephens.

At least 91 records · Page 5Linked to original sources
PubMed1986

Folate induced-hypermotility response after bilateral injection into the nucleus accumbens of the rat. Possible mediation through dopaminergic mechanisms.

Folic acid (FA) and certain of its reduced congeners produce excitatory effects when applied to neuronal tissue. Recent evidence has suggested that folates have other biological properties in common with the excitatory amino acids. The purpose of this study was to determine the activity of folate compounds in a system sensitive to excitatory amino acids. Bilateral injection of folic acid into the nucleus accumbens resulted in a marked increase in locomotor activity at doses of 2.5 and 5 micrograms. Larger doses resulted in behavioral responses, such as body tremor and labored breathing, which interfered with the locomotor response. Similarly, 5-formyltetrahydrofolic acid (FTHF) produced a marked hypermotility response after bilateral injection into the nucleus accumbens (2.5-25 micrograms), while dihydrofolic acid, tetrahydrofolic acid, and 5-methyltetrahydrofolic acid were ineffective. Pretreatment with reserpine (10 mg/kg, i.p.) markedly reduced the hypermotility response elicited by folic acid and FTHF as did pretreatment with haloperidol in both peripheral (0.8 mg/kg) and direct (5 micrograms) injection into the nucleus accumbens. In addition, injection of muscimol (30 ng), which depresses hypermotility induced by dopamine and amphetamine, produced a significant decrease in the hypermotility response produced by folic acid. In contrast, pretreatment with phentolamine (5 mg/kg, i.p.) or propranolol (4 mg/kg, i.p.) did not decrease folic acid or FTHF-induced responses. These results suggest that folic acid and FTHF produce an increase in locomotor activity by facilitating dopaminergic neurotransmission in the nucleus accumbens, possibly by inducing the release of dopamine from the nerve terminals. Thus, these folates have effects similar to those of the excitatory amino acids when injected into the nucleus accumbens.

Animals↗
PubMed1986

Chemotherapy in adult cancer. When is it most useful?

Much has been accomplished in the cure of cancer with chemotherapy, but much remains to be done. The primary care physician's responsibility is to know which cancers are curable and in which a significant portion of patients may benefit from chemotherapy. Patients with a malignancy in a relatively resistant organ site represent the greatest challenge to the "art" of medicine. Even if more than half of patients with a given malignancy are cured by chemotherapy, the remainder deserve the right to participate in research protocols, an undertaking that might further improve these otherwise substantial gains. As research studies show improved cure rates with antineoplastic agents, the need to reduce both short- and long-term side effects will remain a challenge.

Adult↗
PubMed1986

Effect of alternating combination chemotherapy on survival of ambulatory patients with metastatic large-cell and adenocarcinoma of the lung. A Southwest Oncology Group Study.

Using a randomized prospective trial design, chemotherapy with 5-fluorouracil, vincristine, and mitomycin C (FOMi) was compared with cyclophosphamide, doxorubicin, and cisplatin (CAP) and with FOMi alternating with CAP (FOMi/CAP) in 452 eligible patients with metastatic large-cell undifferentiated and adenocarcinoma of the lung. Objective responses were obtained in 26%, 17%, and 22% of patients treated with FOMi, CAP, and FOMi/CAP, respectively. The median survival was similar for FOMi, CAP, and FOMi/CAP therapies (20, 24, and 23 weeks, respectively), but the overall survival (log rank test), 1-year survival, and remission duration were longer for FOMi/CAP-treated patients. Survival was significantly longer for fully ambulatory FOMi/CAP-treated patients compared with either FOMi (P = .01) or CAP (P = .04). Younger patients treated with full doses of therapy responded more often than older patients receiving reduced drug doses (26% and 11%, respectively; P = .003). A prognostic factor regression analysis of all eligible patients indicates that sex, performance status, stage, and treatment assigned were important independent variables determining survival (P less than .05). Toxicity was comparable in each treatment group.

Adenocarcinoma↗
PubMed1986

Activation of excitatory amino acid receptors may mediate the folate-induced stimulation of locomotor activity after bilateral injection into the rat nucleus accumbens.

Folic acid (FA) and 5-formyltetrahydrofolic acid (FTHF) have been shown previously to produce a marked stimulation of locomotor activity after bilateral injection into the rat nucleus accumbens. This study was designed to determine whether the hypermotility response produced by the folates is mediated through the activation of excitatory amino acid receptors in the nucleus accumbens. Although FA stimulated locomotor activity, pteroic acid, a congener of FA that lacks the glutamate moiety, was ineffective, suggesting that the glutamate portion of the molecule is essential for the hypermotility response. The N-methyl-D-aspartic acid (NMDA) receptor antagonists, D-alpha-aminoadipic acid, DL-alpha-epsilon-diaminopimelic acid and MgCl2, at doses that attenuated NMDA-induced hypermotility, were ineffective in decreasing the folate-induced hypermotility response. This behavioral observation is consistent with the biochemical observation that the folates, at a 1 mM concentration, were unable to stimulate the release of [3H]acetylcholine from striatal slices, a model system that is sensitive to the activation of NMDA receptors. In contrast to the ineffectiveness of the NMDA antagonists in inhibiting the response to the folates, the antagonist, glutamic acid diethylester, which inhibited the response to quisqualic acid, but not NMDA, also inhibited the response to both FA and FTHF. Two recently characterized dipeptides, gamma-D-glutamylaminomethylsulfonic acid and gamma-D-glutamyltaurine, antagonized the stimulation of locomotor activity produced by quisqualic acid, FA and FTHF. However, these dipeptides also inhibited the response to NMDA, suggesting that these compounds are not able to distinguish between quisqualate and NMDA receptors in the nucleus accumbens.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Aminoadipic Acid↗
PubMed1986

Adjuvant therapy of breast cancer: Southwest Oncology Group studies.

The Southwest Oncology Group has conducted a series of randomized studies of adjuvant therapy in patients with primary breast cancer and positive axillary nodes. The first study, during which combined chemotherapy with cyclophosphamide, methotrexate, 5-fluorouracil, vincristine, and prednisone (CMFVP) administered for 1 year was compared with single agent therapy with melphalan (L-PAM) for 2 years, was activated in 1975 and closed in 1978. Of the 366 patients who were eligible, 191 received L-PAM and 175 were given CMFVP. The 2 groups were comparable with regard to known prognostic factors. At a median follow-up of 8 years, CMFVP continues to be superior to L-PAM in disease-free (P = .005) and overall survival (P = .01). Thirty-five percent of patients on CMFVP have died compared with 46% on L-PAM. The greatest survival benefit is apparent in premenopausal women and women with 4 or more positive axillary nodes. Acute toxicity was more frequent with CMFVP than with L-PAM, but it was acceptable and reversible with both regimens. Long-term toxicity was limited to myeloproliferative disease in 2 patients on L-PAM and 1 on CMFVP. The second-generation series of studies, activated in 1979, were designed according to nodal status, estrogen receptor (ER) status, and menopausal status. We randomized ER-negative, node-negative patients to 6 months of combination chemotherapy or to no treatment. Because of slow accrual, the study was closed and patients are now being entered onto a similar intergroup study with the Eastern Cooperative Oncology Group. We randomized ER-negative, node-positive patients to either 1 or 2 years of CMFVP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Aggressive adriamycin-containing regimen (PM-FAC) in estrogen receptor-negative disseminated breast cancer. Results of a Southwest Oncology Group trial.

Sixty-four patients with disseminated breast cancer were treated with an aggressive chemotherapy program of prednisone, methotrexate, 5-fluorouracil, Adriamycin (doxorubicin) and cyclophosphamide (PM-FAC). A response rate of 76% was seen in 44 estrogen receptor (ER) negative patients, with 26% achieving complete responses. Forty-two percent of 20 ER positive and unknown patients demonstrated a response, but in none was a complete response achieved. Median response duration was 9 months for complete responders and 5 months for partial responders. The median survival for both groups of patients was 13 months. However, survival among the responding patients was inferior for the ER negative group (median, 14 versus 20 months; P = 0.05). These findings suggest selective sensitivity of ER negative breast cancer to Adriamycin-containing chemotherapy. Despite aggressive chemotherapy, no durable remissions were achieved. Relapse occurred at sites of known prior involvement, and in the central nervous system de novo, especially in the ER negative patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Phase II trial of cyclophosphamide, doxorubicin, and cisplatin (CAP) versus amsacrine in patients with transitional cell carcinoma of the urinary bladder: a Southwest Oncology Group study.

The combination of cyclophosphamide, doxorubicin, and cisplatin (CAP) was reported to be effective in patients with metastatic transitional cell cancer of the urinary bladder. This study was designed to test the effectiveness of the phase II agent amsacrine (m-AMSA) versus CAP in patients previously untreated with systemic chemotherapy, with crossover if no response occurred or at the time of progression. In 23 patients who were randomized to receive CAP, three achieved complete response, seven achieved partial response, six had stable disease, and seven had disease progression. The responses in the 22 patients who received m-AMSA were: one with complete response, three with partial response, six with stable disease, and 12 with progressive disease. The overall response rate to initial CAP therapy was 43% compared to 19% for initial m-AMSA therapy. The median duration of response to CAP was 28 weeks and to m-AMSA was 21 weeks. There were no statistically significant differences in the durations of response or survival times between the groups. The main side effects of CAP were: nausea and/or vomiting, leukopenia, anemia, thrombocytopenia, and renal toxicity. Leukopenia and anemia were the major toxic effects of m-AMSA. Our study supports the justification for testing phase II agent(s) in previously untreated patients with bladder cancer with systemic chemotherapy, provided adequate crossover to a known active single or combination of agents is built into the design of such a trial.

Aged↗
PubMed1985

Phase II trial of mitoxantrone in multiple myeloma: a Southwest Oncology Group Study.

Thirty-five fully evaluable patients with advanced multiple myeloma, refractory to standard chemotherapeutic agents, were entered into a phase II trial with mitoxantrone at a starting dose of 12 mg/m2 iv every 3 weeks. There was one (3%) partial response (lasting 2 1/2 months) in a patient who had received treatment with five different agents, including doxorubicin (total dose, 150 mg/m2). Four additional patients (11%) showed objective evidence of clinical improvement, lasting 4-7 months. Mitoxantrone was well-tolerated with no drug-induced deaths and only moderate to severe leukopenia as the dose-limiting toxicity in the majority of patients. Although mitoxantrone had a low level of activity in this heavily pretreated patient population, consideration should be given to future trials incorporating mitoxantrone into a new drug combination.

Anthraquinones↗
PubMed1984

Response of chronic myelogenous leukemia patients to COAP-splenectomy. A Southwest Oncology Group study.

Eighty-seven patients from 18 institutions with a confirmed diagnosis of chronic myelogenous leukemia were registered on a Southwest Oncology Group protocol for multiagent induction and single-agent maintenance chemotherapy, with randomization to an immunotherapy arm. Elective surgical splenectomy was performed for 42 patients at the completion of 3 months of induction therapy. Final analysis of the study revealed statistically significant survival advantages were correlated with age, splenectomy, the absence of hepatic leukemic infiltrate at the time of splenectomy, and race.

Adolescent↗
PubMed1984

Dose-response and dose-survival advantage for high versus low-dose cisplatin combined with vinblastine and bleomycin in disseminated testicular cancer. A Southwest Oncology Group study.

One-hundred fourteen patients with advanced testicular cancer were randomized to treatment consisting of either high-dose (120 mg/m2, monthly) or low-dose (15 mg/m2, daily X 5 monthly) cisplatin, both combined with vinblastine and bleomycin. There were 60 (53%) complete remissions and 42 partial remissions for an overall response rate of 90%. An additional 11 patients, 4 with carcinoma and 7 with mature teratoma, following surgical cytoreduction, were rendered free of disease. There was a significantly higher complete response rate for high dose induction chemotherapy, 63%, when compared with low dose, 43% (P = 0.03). A survival advantage was also observed for patients receiving high-dose therapy (P = 0.009). For the subgroup of patients with maximal disease and embryonal +/- teratoma +/- seminoma histology there was a clear advantage in favor of high-dose over low-dose therapy both in complete response rate and survival (P = 0.03). There have been only four relapses, all occurring within 1 year of study entry. While there has been a higher frequency of leukopenia, renal, neuromuscular, and mucosal toxicity with high-dose therapy, thus far no irreversible toxicity leading to functional impairment has been seen. The authors have demonstrated a clear-cut relationship for dose of therapy, not only with response and survival, but with the increased potential for cure as well.

Adolescent↗
PubMed1984

Adriamycin and cyclophosphamide versus hydroxyurea in advanced prostatic cancer. A randomized Southwest Oncology Group study.

Over a 24-month period, the Southwest Oncology Group (SWOG) conducted a randomized prospective chemotherapeutic trial in 158 patients with advanced prostatic cancer. Patients were initially randomized to receive either a combination of Adriamycin and cyclophosphamide (AC) or a single agent, hydroxyurea (H), and then crossed over to the other treatment on failure. Of the 137 evaluable patients, 43 (31%) had classically measurable metastatic disease in the lymph nodes, skin, chest, or liver. Focusing their efforts on this subset of patients with measurable disease, the authors of this report found the combination AC to have a superior response rate to the single agent, hydroxyurea. Objective response to AC was seen in 6 of 19 (32%) and in only one of 24 (4%) patients randomized to hydroxyurea (P = 0.06, Fisher's exact test). However, in the larger group of 137 evaluable patients, a survival advantage was not seen for those individuals treated with AC. Failure to demonstrate a survival advantage for an objectively superior drug combination would suggest the need for more active phase II agents in this disease.

Aged↗
PubMed1984

Chlorozotocin: results in colorectal carcinoma treated with high and low doses. A Southwest Oncology Group study.

Clorozotocin was evaluated in patients with advanced colorectal cancer at 225 mg/m2 every six weeks in 14 patients with no prior treatment, at 200 mg/m2 in 43 patients with normal tolerance of prior chemotherapy, and at 100 mg/m2 in 38 patients with extensive or poorly tolerated prior therapy. Median survival for the respective groups was 192, 107 and 79 days; these differences are best explained as a function of performance status. Partial response was reported for one patient, 15 had disease stabilization and two had improvement short of partial remission. Myelotoxicity was acceptable at all doses, with thrombocytopenia being dose limiting at 225 mg/m2. Four patients developed azotemia during or after chlorozotocin treatment. Chlorozotocin has minimal activity against colorectal carcinomas and no dose-response relationship is evident.

Adenocarcinoma↗