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Biomedical subjects

C A Russell

Publications and source records attributed to C A Russell.

At least 55 records · Page 3Linked to original sources
PubMed1991

The role of adjuvant chemotherapy following cystectomy for invasive bladder cancer: a prospective comparative trial.

We assigned 91 patients with deeply invasive, pathological stage P3, P4 or N+ and Mo transitional cell carcinoma of the bladder (with or without squamous or glandular differentiation) to adjuvant chemotherapy or to observation after radical cystectomy and pelvic lymph node dissection. For most patients chemotherapy was planned as 4 courses at 28-day intervals of 100 mg./M.2 cisplatin, 60 mg./M.2 doxorubicin and 600 mg./M.2 cyclophosphamide. A significant delay was shown in the time to progression (p = 0.0010) with 70% of the patients assigned to chemotherapy free of disease at 3 years compared to 46% in the observation group. Median survival time for patients in the chemotherapy group was 4.3 years compared to 2.4 years in the observation group (p = 0.0062). In addition to treatment groups, important prognostic factors included age, gender and lymph node status. The number of involved lymph nodes was the single most important variable. We recommend adjuvant chemotherapy for patients with invasive transitional cell carcinoma after definitive surgical resection.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Treatment of unresectable meningiomas with the antiprogesterone agent mifepristone.

The possibility that meningioma growth may be related to female sex hormone levels is suggested by several lines of evidence. Meningiomas are twice as common in women as in men, have been observed to wax and wane with pregnancy, and are positively associated with breast cancer. A physiological explanation for these phenomena is provided by the finding of steroid hormone receptors in meningiomas. However, unlike breast cancer, meningiomas are much more commonly positive for progesterone receptors than for estrogen receptors. The authors initiated a study on long-term oral therapy of unresectable meningiomas with the antiprogesterone mifepristone (RU486). Fourteen patients received mifepristone in daily doses of 200 mg for periods ranging from 2 to 31+ months (greater than or equal to 6 months in 12 patients). Five patients have shown signs of objective response (reduced tumor measurement on computerized tomography scan or magnetic resonance image, or improved visual field examination). Three have also experienced subjective improvement (improved extraocular muscle function or relief from headache). The side effects of long-term mifepristone therapy have been mild. Fatigue was noted in 11 of the 14 patients. Other side effects included hot flashes in five patients, gynecomastia in three, partial alopecia in two, and cessation of menses in two. Long-term therapy with mifepristone is a new therapeutic option that may have efficacy in cases of unresectable benign meningioma.

Adult↗
PubMed1990

Biochemical and growth inhibition studies of methotrexate and aminopterin analogues containing a tetrazole ring in place of the gamma-carboxyl group.

The biological activities of novel analogues of methotrexate (MTX) and aminopterin (AMT) in which the gamma-carboxyl was replaced by a 1H-tetrazol-5-yl ring, an isosteric group with acidic properties similar to a carboxyl group, were investigated. The tetrazolyl analogues of MTX and AMT were more potent inhibitors of the growth of CCRF-CEM and K562 human leukemia cell lines during continuous (120 h) and 24-h pulse exposure than were the respective parent drugs; only when the exposure time was reduced to 6 h were the parent drugs more potent. These inhibitory effects on growth correlated with the onset of and recovery from inhibition of de novo thymidylate biosynthesis. Growth inhibition by the analogues was protectable by leucovorin. MTX-resistant CCRF-CEM sublines with decreased transport or increased dihydrofolate reductase (DHFR) levels were cross-resistant to the analogues. The analogues were as potent as their parent drugs in inhibiting DHFR activity in vitro and at displacing [3H]MTX from intracellular DHFR. Each analogue was more effective than its parent drug at inhibiting uptake of [3H]MTX into CCRF-CEM cells. The tetrazole analogue of AMT was a linear competitive inhibitor (Kis = 50 microM) of CCRF-CEM folylpolyglutamate synthetase, while the tetrazole analogue of MTX, unlike all other inhibitors, was linear noncompetitive (Kis = 51 microM, Kii = 321 microM). The data suggest that, compared with MTX or AMT, the tetrazole substituent, in place of the gamma-carboxyl group, allows more efficient transport into cells via the reduced folate/MTX carrier and the resulting greater uptake of the analogues leads to inhibition of DNA synthesis and cell death at lower extracellular concentrations during long exposures. The mechanism of cell death could involve inhibition at folypolyglutamate synthetase, but DHFR is the primary target. The low potency of the analogues during short exposure is presumably related to the inability to form the poly-gamma-glutamyl metabolites required for intracellular retention.

Aminopterin↗
PubMed1990

Activation of mammalian folylpolyglutamate synthetase by sodium bicarbonate.

NaHCO3 activated the folylpolyglutamate synthetase (FPGS) from rat liver and the human leukemia cell lines K562 and CCRF-CEM by 1.7- to 2.0-fold. Optimal activation was achieved by 10 mM NaHCO3 in all cases; NaCl, sodium formate, sodium acetate, NaN3, and Na2SO3 at 10 mM did not cause activation. Activation could be masked if assay solutions which had extensively absorbed atmospheric CO2 were used. Activation of the human CCRF-CEM FPGS was examined in detail. Km and Vmax values for pteroyl substrates (aminopterin or methotrexate) and L-glutamate increased proportionally in the presence of NaHCO3; there was thus no apparent change in the catalytic efficiency (Vmax/Km) of the FPGS reaction with these substrates. However, NaHCO3 increased the efficiency of the reaction with respect to ATP by decreasing its apparent Km while increasing the Vmax of the reaction. NaHCO3 also activated FPGS activity when folic acid, dihydrofolic acid and tetrahydrofolic acid were substrates. The relative distribution of products synthesized from methotrexate or tetrahydrofolate by FPGS was not altered by addition of NaHCO3. The potency of 5,8-dideazapteroylornithine, an FPGS-specific inhibitor, was not changed by the presence of NaHCO3 (IC50 = 0.4 microM). These results suggest that FPGS activity with folates and classical antifolates may be activated at physiological concentrations of NaHCO3. In addition, inadvertent contamination of assay solutions with bicarbonate from atmospheric CO2 may cause artifacts in the determination of activity levels and kinetic constants of FPGS.

Animals↗
PubMed1990

A human leukemia cell culture system for testing new antifols: differential sensitivity of lymphoid and nonlymphoid cell lines to unconjugated and methotrexate-conjugated polymers of basic amino acids.

A human cell culture system is described for biological testing of potent new folate-targeted antileukemic drugs that are poorly transported. Basic amino acid (lysine and ornithine) polymers were employed as carriers for increasing the uptake of folate analogs by human leukemia cell lines. In growth inhibition assays, the lymphocytic CCRF-CEM line displayed sensitivities to covalent methotrexate (MTX) conjugates of poly-L-lysine (Mr = 15,000, 50,000, or 100,000) or poly-L-ornithine (Mr = 35,000) which were identical to the sensitivities of these cells to the unconjugated polymers during continuous (120 hr) and pulse (24 hr) exposures; both polymers and conjugates were 50-fold less toxic than unconjugated MTX. The growth inhibitory effects of the polymers or MTX-conjugates were not reversed by simultaneous inclusion of leucovorin, while those of MTX were reversed. In contrast, the nonlymphocytic K562 line showed toxicity by the MTX-conjugates at nontoxic levels of the polymers during continuous, but not pulse, exposures. During continuous exposure the conjugates were only 10-fold less toxic than unconjugated MTX. Toxicities of the MTX-conjugates for the K562 line under continuous exposure conditions were reversed by the simultaneous presence of leucovorin or the lysosomotropic agent leupeptin and thus appeared to be a true antifolate effect which required uptake and lysosomal degradation. This human cell line is thus a suitable system in which to study the effects of antifolates which can be coupled to basic polymers.

Blood Physiological Phenomena↗
PubMed1989

Dose ranging phase I study of the serotonin antagonist GR38032F for prevention of cisplatin-induced nausea and vomiting.

GR38032F is a specific 5-HT3 (serotonin) receptor antagonist with antiemetic activity in animal and early human studies. We performed a dose-ranging phase I study of GR38032F in 43 evaluable patients receiving cisplatin 60 120 mg/m2 for the first time (38 of these patients were chemotherapy-naive). Intravenous GR38032F was administered over a dose range from 0.01 to 0.48 mg/kg given three times at four-hour intervals beginning one half hour before cisplatin, and patients were observed for 24 hours. An additional five patients were treated with 0.18 mg/kg given three times at six-hour intervals. Excellent antiemetic efficacy was noted, with 44% of patients experiencing no vomiting and 26% no nausea. Major protection from vomiting (less than or equal to 2 episodes) and from nausea (less than or equal to 2 hours) was experienced by 81% and 44%, respectively. Mild to moderate headache (40%), lightheadedness (21%), and elevated transaminase (19%) were the most common adverse events reported. One patient experienced an apparent hypersensitivity reaction that responded to conventional medications. No extrapyramidal reactions or akathisia were seen. GR38032F was effective through most of the dose range. However, efficacy decreased at the 0.01 mg/kg level and number and intensity of adverse events increased at the 0.48 mg/kg level. Analysis of those patients receiving high-dose cisplatin (100 to 120 mg/m2) revealed a positive association of GR38032F dose and antiemetic activity (Fisher's exact test, two-sided; P less than .05). The 5-HT3 receptor antagonists may provide antiemetic efficacy similar to high-dose metoclopramide without antidopaminergic toxicity. The maximum recommended dose on this schedule of GR38032F is 0.36 mg/kg.

Adult↗
PubMed1988

Preferences for treatment control among adults with cancer.

The preferences of adults with cancer about alternative roles they might play in treatment decision making was examined. The hypothesis was that people with cancer have ideal points along the psychological dimension of keeping, sharing, or giving away control over decision making. A theoretical sample of 60 ambulatory oncology patients was tested using two card-sort procedures with a total of eight vignettes describing various patterns of control over treatment decision making. Results indicated that preference orders of 59/60 patients were consistent with the existence of an underlying psychological dimension, "preferences for control over treatment decision making"; that most patients preferred the pattern of shared control; and that patients preferred to give control to the physician rather than a family member.

Adult↗
PubMed1986

Role of dietitians in enteral feeding.

Awareness of the nutritional requirements of inpatients has been sadly neglected for many years. Students in British medical schools are taught little about clinical nutrition and the role of the dietitian. Dietitians, on the other hand, spend four years learning the science of nutrition and dietetics. In most hospitals in Britain dietitians are responsible for giving advice on a wide range of therapeutic diets, and only a minority specialize in one particular aspect of nutrition and dietetics. Recent changes and developments in nutritional support have offered an exciting and interesting challenge to dietitians, who with their well established background in nutrition, can play an important part in the nutritional care team.

Allied Health Personnel↗
PubMed1970

Human factory.

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Hospitals, Teaching↗