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Biomedical subjects

E Frei

Publications and source records attributed to E Frei.

At least 145 records · Page 8Linked to original sources
PubMed1991

Effect of dietary calorie and fat restriction on mammary tumor growth and hepatic as well as tumor glutathione in rats.

Effect of dietary calorie restriction and fat reduction on growth of established mammary carcinoma in rats and on glutathione levels in liver and tumor tissue was investigated. Reduced (GSH) and oxidized (GSSG) glutathione were determined enzymatically. Female Sprague-Dawley rats were injected with 25 mg/kg methylnitrosourea (MNU) on day 50 of life for tumor induction, and subsequently fed a diet containing 50 kcal/day with 45% (energy %) fat. When tumors reached approximately 1 cm3, the diet was changed for 10 +/- 2 weeks. Four dietary groups were formed: two high calorie groups (50 kcal/day) with 45% or 25% fat and two calorie restricted groups (35 kcal/day) with 45% or 25% fat, respectively. Tumor growth was significantly inhibited by the 30% calorie restriction, and the inhibition was most effective in the calorie restricted group with low fat level. However, reduction of fat, alone, had no significant inhibitory effect. GSSG levels in both liver and tumor showed no differences among the groups. Hepatic GSH levels tended to be lower in the calorie-restricted groups, and showed no difference between isocaloric groups with different fat levels. In contrast, GSH in tumor tissue tended to be lower in the low fat groups, independently of calorie levels.

Animals↗
PubMed1991

Modulation of alkylating agents by etanidazole and Fluosol-DA/carbogen in the FSaIIC fibrosarcoma and EMT6 mammary carcinoma.

Tumor cell survival assay in the FSaIIC murine fibrosarcoma demonstrated that when the modulator Fluosol-DA (0.3 ml; 12 ml/kg i.v.) was administered just prior to an alkylating agent plus carbogen breathing for 6 h or the modulator etanidazole (1 g/kg i.p.) was administered just prior to an alkylating agent, the combination treatment produced significantly more tumor cell killing across the dosage range of each alkylating agent tested compared with the alkylating agent alone. Each alkylating agent produced a dose-dependent log-linear tumor cell survival curve. There was an increase in tumor cell killing of 5-10-fold when either Fluosol-DA/carbogen or etanidazole was added to treatment with the alkylating agent. For cis-diamminedichloroplatinum(II) (CDDP) and N,N',N''-triethylenethiophosphoramide, the modulators used in combination increased tumor cell killing by only 2-3-fold over that obtained with a single modulator, but for the other alkylating agents, tumor cell killing was increased by 10-50-fold when the combination of modulators was used. Bone marrow granulocyte-macrophage colony-forming unit survival assays showed that the combination of modulators with the alkylating agents resulted in only small increases in bone marrow toxicity of the alkylating agents except for N,N',N''-triethylenethiophosphoramide and L-phenylalanine mustard (L-PAM), for which the toxicity to the bone marrow granulocyte-macrophage colony-forming unit was increased by 5-10-fold compared with the alkylating agents alone. The Hoechst 33342 dye diffusion defined tumor cell subpopulation assay, also in the FSaIIC tumor, demonstrated that the combination of modulators increased the toxicity of CDDP, cyclophosphamide, L-PAM, and 1,3-bis(2-chloroethyl)-1-nitrosourea by 9-55-fold compared with the alkylating agent alone in both the bright (euxoic-enriched) and dim (hypoxic-enriched) cells. For each alkylating agent except 1,3-bis(2-chloroethyl)-1-nitrosourea, the increase in tumor cell killing was greater in the dim cells than in the bright cells. Finally, tumor growth delay studies in both the FSaIIC tumor and the EMT-6 murine mammary adenocarcinoma confirmed that the combination of modulators significantly increased the tumor growth delay caused by CDDP, carboplatin, cyclophosphamide, N,N'N"-triethylenethiophosphoramide, L-PAM, and 1,3-bis(2-chloroethyl)-1-nitrosourea. The greatest increases (4-5-fold) were observed for carboplatin and L-PAM in the FSaIIC tumor and CDDP and cyclophosphamide in the EMT-6 tumor. These results suggest that Fluosol-DA/carbogen together with etanidazole may be an effective modulator combination of alkylating agents in the clinic.

Alkylating Agents↗
PubMed1991

Lonidamine as a modulator of alkylating agent activity in vitro and in vivo.

We are searching for relatively nontoxic compounds that can positively modulate the efficacy of antitumor alkylating agents. Lonidamine inhibits cellular energy metabolism and could potentially increase damage by alkylating agents if cellular defenses are energy requiring. Exposure of cells to lonidamine (500 microM) for 2 h under hypoxic conditions followed by 1-h exposures to lonidamine plus alkylating agents under normally oxygenated conditions in vitro significantly increased the cell kill achieved by cis-diamminedichloroplatinum(II) (CDDP) approximately 5-fold and by D-tetraplatin approximately 10-fold at 90% inhibitory concentration in MCF-7/CDDP (CDDP-resistant) cells. Carboplatin cytotoxicity, however, was little changed. In the MCF-7 parent cell line, treatment with lonidamine increased CDDP cytotoxicity by approximately 10-fold, D-tetraplatin by approximately 10-fold, and carboplatin by approximately 8-fold at the 90% inhibitory concentration. For L-phenylalanine mustard (melphalan), N,N',N"-triethylenethiophosphoramide (thiotepa), and N,N'-bis(2-chloroethyl)-N-nitrosourea, little resistance was evident in the MCF-7/CDDP lines compared with the parent line. Treatment with lonidamine increased the cytotoxicity of each drug by 1.5- to 3-fold in both cell lines. When exposure to lonidamine was extended to 24 h before and 12 h after drug exposure in MCF-7 normally oxygenated cultures, CDDP (250 microM) cytotoxicity was increased by approximately 100-fold, but melphalan cytotoxicity was increased only 2- to 3-fold over the concentration range tested. In the FSaIIC murine fibrosarcoma tumor system, five i.p. injections of 50 mg/kg of lonidamine over 36 h increased the tumor cell kill by CDDP and carboplatin approximately 2- to 3-fold over the dose range tested when the platinum complexes were given i.p. immediately after the third lonidamine injection. When cyclophosphamide and thiotepa were given in the same schedule, 10-fold increases in tumor cell killing were evident on tumor excision assay over the dosage ranges. The increase in bone marrow toxicity caused by lonidamine in addition to the alkylating agents was less than for tumor cells. Finally, in the EMT6 murine mammary carcinoma, use of lonidamine at 500 mg/kg twice daily along with CDDP, carboplatin, thiotepa, and cyclophosphamide significantly increased tumor growth delays by approximately 1.6- to 3.0-fold. The results suggest that lonidamine can positively modulate antitumor alkylating agent cytotoxicity and may be a clinically useful adjunctive therapy with these drugs.

Animals↗
PubMed1991

Characteristics of five human tumor cell lines and sublines resistant to cis-diamminedichloroplatinum(II).

In order to study the mechanisms responsible for resistance to CDDP, 5 human tumor cell lines were made resistant to CDDP by repeated in vitro exposures. After cloning it was found that the cell lines developed were between 3.3-fold and 17-fold more resistant to CDDP than the parental cell lines at the IC90. These lines were also resistant to carboplatin and tetraplatin; however, resistance to tetraplatin was lower than to the other platinum complexes. Sensitivity was also assessed to Adria, MTX, 5-FU, chlorambucil, 4-HC, 4-HIF, BCNU, Thiotepa, HN2, Mito C and L-PAM, and no consistent cross-resistance was observed. As compared with the parental lines, non-protein sulfhydryl content was elevated in 3 resistant lines, and protein sulfhydryl was elevated in all 5 lines, as was glutathione-S-transferase activity. Measurements of platinum in whole cells and nuclei after exposure of the cultures to 25 microM CDDP for either 1 or 6 hr showed that nuclear levels reflected those in whole cells and that, per mg protein, platinum levels were lower in resistant cells at both time points. Formation of DNA cross-links, determined by alkaline elution, was lower in resistant cell lines than in parental cell lines, but did not correlate with the absolute cell kill observed. These results indicate that cellular resistance to CDDP often involves decreases in drug accumulation and increases in protein sulfhydryl content. Possible strategies for overcoming these mechanisms are discussed.

Adenocarcinoma↗
PubMed1991

Fluosol-DA/carbogen with lonidamine or pentoxifylline as modulators of alkylating agents in the FSaIIC fibrosarcoma.

In an effort to increase the efficacy of several antineoplastic alkylating agents (CDDP, L-PAM, CTX, or BCNU), we examined the effect of the modulator Fluosol-DA/carbogen in combination with a second modulator, either lonidamine or pentoxifylline, on the survival of FSaIIC tumor cells and of bone marrow CFU-GM from tumor-bearing C3H mice. Fluosol-DA/carbogen increased the tumor-cell killing activity of each alkylating agent by about 10 times. In contrast, lonidamine alone did not significantly increase the cytocidal activity of any of the alkylating agents tested. However, in combination with Fluosol-DA/carbogen, the use of lonidamine produced about a 100-fold increase in the tumor cell kill achieved with CDDP as compared with CDDP alone. No increase in tumor cell kill over that produced with the single modulator Fluosol-DA/carbogen was seen following the addition of lonidamine to the combination treatment with L-PAM, CTX, or BCNU. Unfortunately, although neither lonidamine nor Fluosol-DA/carbogen alone significantly increased alkylator toxicity to bone marrow CFU-GM, the combination of modulators increased the toxicity of each alkylating agent to bone marrow by about 10 times. Pentoxifylline caused an increase in alkylator activity against the FSaIIC fibrosarcoma only when used with BCNU; this effect was further augmented by the addition of Fluosol-DA/carbogen. The combination of modulators pentoxifylline plus Fluosol-DA/carbogen was more effective than Fluosol-DA/carbogen alone only when the former was used with BCNU, whereas only minimal increases in tumor-cell killing activity were obtained with this modulator combination and CDDP, L-PAM, or CTX. Pentoxifylline increased the bone marrow CFU-GM toxicity of L-PAM by about 10 times. The bone marrow CFU-GM toxicity was further increased by Fluosol-DA/carbogen, as was the toxicity of each of the other alkylating agents. Lonidamine plus Fluosol-DA/carbogen may be useful in increasing the therapeutic efficacy of CDDP, and the combination of pentoxifylline plus Fluosol-DA/carbogen might improve the antitumor activity of BCNU.

Alkylating Agents↗
PubMed1991

Combination of etanidazole with cyclophosphamide and platinum complexes.

In an effort to improve the therapeutic efficacy and selectivity of cyclophosphamide (CTX), cis-diamminedichloroplatinum(II) (CDDP), and carboplatin (Carbo), these antitumor alkylating agents were combined with the 2-nitroimidazole drug etanidazole (ETA). As revealed by tumor-cell survival assay in the FSaIIC murine fibrosarcoma, the addition of ETA (1 g/kg, i.p.) just prior to the i.p. injection of various doses of the alkylating agents resulted in increases in the tumor-cell kill produced by each drug (CTX, 10-fold; CDDP, 20-fold; and Carbo, 5- to 15-fold), whereas toxicity to bone marrow granulocyte-macrophage colony-forming units (CFU-GM) increased only about 0- to 3-fold. When CTX was combined with either CDDP or Carbo, striking increases in tumor-cell killing were observed (20- to 100-fold across the CDDP dose range and 5- to 20-fold across the dose range of Carbo), which were supra-additive for CDDP and additive for Carbo as revealed by isobologram analysis. The addition of ETA to these alkylating-agent combinations produced a further approx. 20-fold increase in tumor-cell kill for both CTX/CDDP and CTX/Carbo. This effect was greatest at the lowest dose of the platinum drug tested and was supra-additive in the case of CDDP and additive for Carbo. Following treatment with ETA/CTX/CDDP, bone marrow CFU-GM toxicity increased only about 5-fold over that of CTX/CDDP alone, but the injection of ETA/CTX/Carbo resulted in a 10- to 20-fold increase in bone marrow toxicity as compared with that obtained using CTX/Carbo alone. Tumor growth-delay studies revealed significant increases in the antitumor effect of the alkylating agents when these were given in combination with ETA. Both the ETA/CTX/CDDP and the ETA/CTX/Carbo combinations produced tumor growth delays of 23 days, which represented approx. 1.6-fold increases over those obtained using the alkylating-agent combinations alone. These results suggest that ETA could significantly improve the therapeutic efficacy of these alkylating agents, whether they are given individually or in combination.

Animals↗
PubMed1991

A phase I trial of continuous-infusion cyclophosphamide in refractory cancer patients.

Cyclophosphamide demonstrates enhanced tumoricidal activity with decreased bone marrow toxicity when given on a divided-dose schedule in certain animal models. A total of 22 patients presenting with refractory metastatic cancer were treated in a phase I trial of continuous infusion of cyclophosphamide over 96 h. Granulocytopenia of less than 500/microliters that lasted for greater than 14 days or thrombocytopenia of less than 25,000/microliters that lasted for greater than 14 days was the target dose-limiting toxicity in the absence of nonhematologic grade 4 toxicity. The maximal tolerated dose was 7 g/m2. Three patients died. Of 21 evaluable patients, 9 responded, including 8/9 who had experienced disease progression during prior oxazaphosphorine-containing combination chemotherapy. Clinically meaningful responses were observed in patients who had demonstrated clinical resistance to an oxazaphosphorine drug given at lower doses.

Adolescent↗
PubMed1991

Escalating doses of carboplatin with high-dose ifosfamide using autologous bone marrow as support: a phase I study.

In this phase I study, 16 adult cancer patients were treated with concurrent 4-day continuous infusions of ifosfamide at 12 g/m2 and escalating doses of carboplatin (400-1600 mg/m2) to determine the major non-haematological dose-limiting toxicity of the combination. Mesna was given by continuous infusion over 5 days for uroprotection (total dose per course = 15 g/m2). Autologous bone marrow support, which was mandated for subsequent dose levels once granulocytes remained below 500/microliters for more than 14 days in at least 2 patients entered at a given dose level, was used at dose levels above 400 mg/m2 carboplatin. Renal toxicity became dose-limiting at the maximum tolerated dose level of 1600 mg/m2 carboplatin. Temporary creatinine elevations above 2 mg/dl (median peak 2.6 mg/dl) were observed in 3 and irreversible renal toxicity occurred in 1 (peak creatinine 6.9 mg/dl, chronic creatinine 5-6 mg/dl) of the 5 patients entered at this dose level. Severe confusion and lethargy associated with rising creatinine developed in 2 patients. Two complete and four partial responses were documented in 14 heavily pretreated evaluable patients. The complete responses continue at 14+ and 20+ months in a patient with germ cell carcinoma and Ewing's sarcoma, respectively. Carboplatin appears to contribute to the renal toxicity of ifosfamide. Nevertheless, the combination of carboplatin and ifosfamide at 80% and 75% of the single-agent maximal tolerated doses respectively produced acceptable non-haematological toxicity. Further studies in the treatment of sarcoma, germ cell, ovarian and lung carcinomas with this combination are warranted.

Adult↗
PubMed1991

Chemoresistance in rat ovarian tumours.

In a cisplatin resistant subline (O-342/DPP) of an intraperitoneally growing transplantable rat ovarian tumour (O-342), intracellular glutathione (GSH) was approximately doubled (mean [S.E.] 1.5 [0.26] vs. 0.8 [0.2] nmol/10(6) cells). GSH reductase activity was higher (30.64 [4.07] vs. 20 [0.92] nmol/min per mg protein), although no difference was found for GSH-S-transferase. 24 h after exposure to cisplatin, formation of DNA interstrand cross-links was at a maximum in both lines and significantly higher in O-342 (162 [23] vs. 88 [22] rad eq). Combination treatment of O-342/DDP with buthionine sulphoximine plus cisplatin resulted in a marginal increase in survival compared with cisplatin treatment; treatment of this line with 3-aminobenzamide plus cisplatin was also superior to cisplatin alone. In the sensitive line both combinations were likewise superior to cisplatin alone. In vitro, at equimolar concentration, a new platinum complex (CTDP) was at least as active as cisplatin in both lines, which suggests a superior therapeutic index because its LD50 in mice is threefold higher than that of cisplatin. A ruthenium complex (ICR) had a higher activity in the resistant line. A titanium complex (budotitane) was not active.

Animals↗
PubMed1991

The role of peroxidases in the activation of chemical carcinogens.

Peroxidases exhibit a wide substrate specificity with respect to various carcinogenic xenobiotics. Peroxidase-mediated activations of several carcinogenic polycyclic aromatic hydrocarbons, aromatic amines, phenols, azo dyes and N-nitrosamines are reviewed, considering their possible involvement in the initiation of chemical carcinogenesis. Activation pathways of these carcinogens examined in vitro, in subcellular fractions, cell cultures and in vivo are evaluated.

Animals↗
PubMed1991

[Laparoscopic cholecystectomy--results of the first 100 cases].

100 patients underwent laparoscopic cholecystectomy for symptomatic gallbladder stones. In seven cases the laparoscopic procedure had to be converted into an open cholecystectomy due to bleeding, choledochus injury and acute cholecystitis. There were no complications postoperatively. We feel that the indication of this method is advantageous. Independent of the size, the number and the chemical composition, this method is used for symptomatic gallbladder stones. All together the main advantages are higher comfort for the patient, better cosmetic results, shortening of hospital stay and sooner return to full activity.

Adult↗
PubMed1991

Subcellular fractions of rat organs contain nitroreductases which reduce N-nitrodimethylamine to N-nitrosodimethylamine.

The nasal carcinogen N-nitrodimethylamine was reduced to its N-nitroso analogue N-nitrosodimethylamine in vivo. Liver-soluble fraction and brain mitochondria contained enzymes capable of reducing this compound. The activity was only partly inhibited by oxygen; NADPH and NADH served as cosubstrates. N-Nitromethylamine is also carcinogenic and was reduced by liver cytoplasm to a protein binding species (methyldiazohydroxide?).

Animals↗
PubMed1991

Modulation of alkylating agents by lonidamine in vivo.

We are searching for relatively nontoxic compounds that can positively modulate the efficacy of antitumor alkylating agents. Lonidamine inhibits cellular energy metabolism and could potentially increase damage by alkylating agents if cellular defenses are energy-requiring. In the FSaIIC murine fibrosarcoma tumor system, 5 intraperitoneal (IP) injections of 50 mg/kg of lonidamine over 36 hours increased the tumor cell kill by cisplatin, carboplatin, D-tetraplatin, melphalan and BCNU approximately two- to threefold over the dosage ranges of each drug tested when the antitumor agents were given IP immediately after the third lonidamine injection. When cyclophosphamide and thiotepa were given in the same schedule, 10-fold increases in tumor cell killing were evident on tumor excision assay over the dosage ranges for each drug. The increase in bone marrow toxicity caused by lonidamine in addition to the alkylating agents, cisplatin, carboplatin, and BCNU was less than for tumor cells. Dose modifying effects were observed in the killing of bone marrow colony forming units-granulocyte-macrophage progenitors (CFU-GM) by cyclophosphamide, thiotepa and melphalan but at standard doses of cyclophosphamide and thiotepa there was no increase in the killing of bone marrow CFU-GM with the addition of lonidamine to treatment with these drugs. The results suggest that lonidamine can positively modulate tumor cell killing by some antitumor alkylating agents and may be a clinically useful adjunctive therapy with these drugs.

Alkylating Agents↗
PubMed1991

Curing leukemia.

Explore the source record for details and available documents.

Acute Disease↗
PubMed1990

[Laparoscopic cholecystectomy--results in the initial 100 cases].

100 patients underwent laparoscopic cholecystectomy for symptomatic gallbladder stones. In seven cases the laparoscopic procedure had to be converted into an open cholecystectomy due to bleeding, injury to the choledochus and acute cholecystitis. There were no postoperative complications. We feel that the indication for this method is broad. Independent of the size, the number and the chemical composition of calculi, this method is used for symptomatic gallbladder stones. All together the main advantages are higher comfort for the patient, better cosmetic results, shortening of hospital stay and sooner return to full activity.

Adult↗