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Biomedical subjects

Y Rustum

Publications and source records attributed to Y Rustum.

15 recordsLinked to original sources
PubMed1992

Reactivation of insulin-like growth factor II during hepatocarcinogenesis in transgenic mice suggests a role in malignant growth.

We have studied the expression of insulin-like growth factor II (IGF-II) during hepatocarcinogenesis in four independent transgenic mouse lines. In all four lines liver-directed transgene expression induces a stepwise and relatively synchronized tumorigenesis. IGF-II reexpression occurs in all four lines irrespective of the mechanism of tumor induction. Reexpression is chronologically associated with late progression steps toward hepatocellular carcinoma and correlated with the respective tumor progression rate in each line. IGF-II activation is focal and topographically associated with high replicative activity. IGF-II mRNAs in hepatocellular carcinomas show similarities to the expression pattern in fetal liver, and a M(r) 15,000 IGF-II polypeptide accumulates intracellularly in distinct cytoplasmic preferentially perinuclear compartments. These data indicate that IGF-II reexpression is a marker for progression to hepatocellular carcinoma and may contribute to hepatocarcinogenesis via an autocrine mechanism.

Animals↗
PubMed1992

Effect of tetrahydrouridine on metabolism and transport of 1-beta-D-arabinofuranosylcytosine in human cells.

Deamination of cytosine arabinoside (ara-C) by cytidine deaminase is the main mode of inactivation of this drug which can be responsible for ara-C resistance. The present study was undertaken to determine the effect of tetrahydrouridine (THU; a potent inhibitor of cytidine deaminase) on ara-C transport and metabolism in human cells. A rapid transport of ara-C into freshly isolated hepatocytes and an increased intracellular accumulation of the unchanged drug were observed in the presence of 50 micrograms/ml THU. THU inhibited the intracellular deamination of ara-C by 80% and slowed elimination of the compound extracellularly. The intracellular ara-C concentrations achieved after incubation with 1 micrograms/ml ara-C plus 50 micrograms/ml THU are similar to those attained with ara-C (10 micrograms/ml) alone. Treatment of leukemic K562 cells with the combination of THU (50 micrograms/ml) and ara-C (1 micrograms/ml) led to an augmentation of intracellular ara-C triphosphate formation up to twofold.

Cells, Cultured↗
PubMed1992

Cisplatinum in combination with 5-fluorouracil and citrovorum factor in the treatment of advanced colorectal carcinoma.

A phase II trial of citrovorum factor, 500 mg/m2/week, plus 5-fluorouracil, 400 mg/m2/week on day 1, and cisplatin, 20 mg/m2/week on day 2, was carried out in a group of 40 patients with metastatic colorectal carcinoma. A partial response with a mean duration of 8.4+ months was achieved in 24% of patients, a minimal response with a mean duration of 5.4 months was obtained in 6% of patients, and a stabilization of 6.2 months was achieved in 41%. Ten patients (29%) progressed. A 38% partial response rate was seen in patients with advanced rectal carcinoma, whereas no response was obtained in patients with colon cancer. Interestingly, 5 partial responses were seen in 12 patients pretreated with 5-fluorouracil. The overall survival was 9.8+ months. The mean survival of patients who achieved a partial response was 12.0+ months, whereas patients who progressed survived a mean of 6.6+ months. Patients with colon cancer had a mean survival of 8.1+ months, and those with rectal cancer survived a mean of 11.1+ months. This difference was not statistically significant. The treatment was generally very well tolerated, with patients showing mostly grade 1-2 gastrointestinal and/or hematological toxicity.

Adult↗
PubMed1991

A phase I study of cisplatinum plus 5-fluorouracil in modulation with citrovorum factor in metastatic colorectal carcinoma.

A phase I study of 5-fluorouracil 600 mg/m2/week and folinic acid 500 mg/m2/week on day 1 and cisplatin administered weekly on day 2 was carried out on 30 patients with metastatic colorectal carcinoma of which 20 patients were pretreated with 5-fluorouracil. The first group of patients received cisplatin at the dose of 5 mg/m2/week. Cisplatin was then escalated to 10, 15, 20, 25, 30, and 35 mg/m2/week for subsequent groups of patients. Gastrointestinal side-effects were the dose-limiting toxicity. A therapy related death was seen at the dose of 35 mg/m2/week of cisplatin. The maximally tolerated dose of cisplatin in combination with 5-fluorouracil and citrovorum factor is 20 mg/m2/week. The optimally tolerated dose of 5-fluorouracil is 400 mg/m2/week in modulation with citrovorum factor 500 mg/m2/week. The recommended doses for a phase II study are cisplatin 20 mg/m2/week, 5-fluorouracil 400 mg/m2/week, and citrovorum factor 500 mg/m2/week.

Adult↗
PubMed1990

Isolation and characterization of renin-expressing cell lines from transgenic mice containing a renin-promoter viral oncogene fusion construct.

We constructed transgenic mice containing a renin-promoter SV40 T antigen fusion transgene with the intention of inducing neoplasia in renin-expressing cells and isolating renin-expressing cell lines in vitro. We examined six kidney tumors from mice representing three different transgenic lines and found they expressed their endogenous renin gene. Initially, five nonclonal kidney tumor-derived cell lines were established which expressed their endogenous renin gene in addition to the transgene. They retained active renin intracellularly and constitutively secreted an inactive form of renin (prorenin). One of these cell lines was cloned to homogeneity. This line maintained high level expression of renin mRNA throughout 3 months of continuous culture. Although the cells contained an equal proportion of active and inactive renin, the species constitutively secreted into the media was predominantly (95%) prorenin. However, active renin secretion was stimulated 2.3- and 4.6-fold by treatment with 8-bromo-cAMP after 4 and 15 h, respectively. In addition, the presence of multiple secretory granules was confirmed by ultrastructural analysis. These cells, which express renin mRNA and can regulate secretion of active renin, should provide an excellent tool for studying renin gene regulation and secretion. Furthermore, these mice should provide a useful source for the establishment of renin-expressing cell lines from a variety of renin-expressing tissues.

Animals↗
PubMed1990

Formulation, stability, and antitumor activity of 1-beta-D-arabinofuranosylcytosine conjugate of thioether phospholipid.

1-beta-D-Arabinofuranosylcytosine 5'-diphosphate-rac-1-S-octadecyl-2-O- palmitoyl-1-thioglycerol (ara-CDP-DL-PTBA) is an effective stable 1-beta-D-arabinofuranosylcytosine (ara-C) conjugate of thioether phospholipid against a variety of transplantable tumors in mice. The conjugate was formulated in a micellar solution by sonication, in which the conjugate exists as micellar discs (size, 0.01 to 0.04 micron). Analyses on thin-layer and high-pressure liquid chromatography showed that the conjugate was chemically stable upon storage at 3-4 degrees C for more than a 6-mo period. However, stored at room temperature for 3 mo it began to degrade (3 to 11%) to 1-beta-D-arabinofuranosylcytosine 5'-monophosphate and phosphatidic acid. At 3-4 degrees C, the micellar structure remained generally unchanged for 6 mo (size, less than 0.1 micron). Samples stored for 4 mo at room temperature formed some larger vesicles (size, 0.1 to 0.4 micron). Antitumor activity against i.p. implanted L1210 leukemia in mice remained relatively constant with samples stored for 6 mo at 3-4 degrees C or 3 mo at room temperature. 1-beta-D-Arabinofuranosylcytosine 5'-triphosphate (ara-CTP) levels were elevated (greater than 500 pmol/10(7) cells) in L1210 leukemia cells within 1 h following i.p. administration of 400 mg/kg of ara-CDP-DL-PTBA to mice. More importantly, retention of cellular ara-CTP was prolonged (greater than 24 h) in these tumor cells as compared with ara-C treatments. Administration of ara-CDP-DL-PTBA to mice with colon 26 carcinoma (s.c.) resulted in both significant antitumor activity with an increased life span greater than 100% and decreased tumor size. The conjugate also demonstrated a dose-dependent therapeutic effect in mice with M5076 sarcoma (s.c.) as demonstrated by decreases in tumor size and liver metastases. Overall, ara-CDP-DL-PTBA, a stable lipid conjugate of ara-C in a micellar solution, appears to offer substantial therapeutic benefit to mice with leukemia and solid tumors warranting its further development and clinical investigation.

Animals↗
PubMed1990

Assessment of human genitourinary tumors and chemosensitivity testing in 3-dimensional collagen gel culture.

A recently described collagen gel culture technique has been modified to evaluate the growth characteristics and chemosensitivity patterns of genitourinary neoplasms. Fresh human surgical explants incorporated radiolabeled DNA precursors [H3)thymidine or deoxyuridine) in 97% of 38 patient specimens (18/19 bladder, 3/3 prostate, 2/2 testis, 13/14 renal), after being maintained for three to 13 weeks/passage, with several specimens reaching their sixth passage (20 months). Control cellular DNA incorporation ranged from five to 90% (#cells labeled/#cells evaluated), with median labeling for bladder 30%, prostate 80%, testis 90%, and renal 80%. Original histopathologic classification was maintained in all cases. Tumor volume and glucose consumption were other measurable parameters. Seventy-three surgical specimen cultures were treated with chemotherapeutic agents after a minimum of four weeks in culture. Single agent exposures were 24 hours at 1X and 10X reported peak plasma concentrations. Combination agents were sequenced as in current clinical protocol for bladder tumors and fourteen day continuous fluorodeoxyuridine (FdURD) exposure for renal tumors. Sensitivity was found in 1/2 prostate and 1/10 renal tumors to Adriamycin, 8/15 bladder and 1/2 testis tumors to cisplatin, 11/28 renal tumors to FdURD and 6/16 bladder tumors to MVAC combination chemotherapy. This culture system offers the advantages of in vivo-like solid tumor growth, a high culture success rate, longevity in culture, maintenance of the primary histopathology and reproducible chemosensitivity response.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

A phase I-II study on the toxicity and therapeutic efficacy of 5-fluorouracil in combination with leucovorin and cisplatinum in patients with advanced colorectal carcinoma.

5-Fluorouracil (5-FU) has been the treatment of choice for colorectal carcinoma with an overall response rate of about 20%. Recent studies have shown that folate (LV) can increase 5-FU therapeutic efficacy, achieving about a 40% response rate without a clear impact on survival. Cisplatinum (CDDP) is usually inactive in colorectal carcinoma, but the association with 5-FU results in a synergistic antineoplastic effect. A phase I-II study was done to assess the maximally tolerated dose (MTD) of CDDP in association with 5-FU + LV. The MTD for CDDP was 20 mg/m2/wk in association with 5-FU 400-500 mg/m2/wk and LV 500 mg/m2/wk. WHO criteria were used for evaluation of both toxicity and response. In the phase I part we found that the main side-effect in 27 evaluable patients (pts) was gastrointestinal toxicity, mainly in the form of nausea/vomiting (92%) and diarrhea (70%) which caused one therapy-related death. Renal (26%) and marrow (59%) toxicity were acceptable. In the phase II part of the study 1 out of 19 evaluable pts (5%) had a complete response of 309 days, 3 pts achieved a partial response (16%) with a median duration od 410 days, 2 pts had a minimal response (10%) with a median duration of 261 days, and 8 pts experienced no change (42%) with a mean duration of 196 + days. In our opinion the 21% response rate obtained in this series is not satisfactory. Nevertheless the very high number of minimal response + no change patients together with the interesting impact on survival in responders may suggest further phase II-III studies.

Adult↗
PubMed1979

Treatment of acute nonlymphocytic leukemia: use of anthracycline-cytosine arabinoside induction therapy and comparison of two maintenance regimens.

Patients with acute nonlymphocytic leukemia were given remission induction therapy consisting of cytosine arabinoside and an anthracycline. Those patients who experienced complete remission received two courses of consolidation therapy and were randomized to receive maintenance therapy consisting of either daily chemotherapy with reinforcements every 3 mo or reinforcement therapy only every 6 wk. The overall complete remission rate was 66%, with 80% complete remission for previously untreated patients less than 60 yr of age who did not have a prior history of malignancy. Remission durations were the same for patients treated with both maintenance regimens. The major determinant for successful remission induction therapy was patient age, with older patients frequently succumbing to intercurrent infection. Documented leukemic cell resistance to the therapy employed was only rarely encountered. Once remission was achieved, age was no longer a determinant of patient survival, since duration of remission was independent of age. Remission durations were directly related to leukemic cell retention of cytosine arabinoside triphosphate. Hence therapy for acute nonlymphocytic leukemia can be divided into two separate areas: remission induction and remission maintenance.

Adolescent↗
PubMed1978

Friend leukemia cells: relationship between differentiation, clonogenicity and malignancy.

Friend leukemia cells were cultured in vitro in the presence or absence of agents which induce erythroid differentiation. The cultures were harvested and the degree of differentiation determined. Clonogenicity of the cells in vitro and malignancy in vivo were determined as well. There was an inverse exponential relationship between the degree of differentiation and the clonogenicity of the culture. Differentiation was also associated with a modest decline in malignancy. Of interest was the observation that bromodeoxyuridine inhibited the biochemical manifestations of erythroid differentiation, but did not prevent the decline in clonogenicity which accompanied differentiation.

Animals↗
PubMed1977

Biochemical characteristics, metabolism, and antitumor activity of several acetylated hexosamines.

We have synthesized several potential inhibitors and/or modifiers of the carbohydrate portion of plasma membrane glycoconjugates. These include fluorinated and actylated analogs of D-glucosamine, D-galactosamine, and D-mannosamine. These compounds have been tested to determine their effects on both[14C] glucosamine and [3H] leucine incorporation into glycoconjugate and on cell growth and viability using P-288 murine lymphoma cells maintained in tissue culture. The most cytotoxic agent tested was 2-acetamido-2-deoxy-1,3,4,6-tetra-O-acetyl-beta-D-glucopyranose or simply beta-pentaacetylglucosamine which prevented cell growth at 10(-4)-10(-3) M. beta-Pentaacetylglucosamine cytotoxicity was correlated with its high lipid solubility, having an octanol/water partition coefficient of 0.424 as compared with 0.278 for the alpha-anomer and 0.017 for N-acetylglucosamine. In vitro metabolism studies with [4C]- and/or [3H]-labeled pentaacetylglucosamine have indicated intracellular de-O-acetylation leading to the biosynthesis of UDP-N-acetylglucosamine, followed by the incorporation of this sugar into cellular glycoprotein. Concomitant with the formation of increased amounts of this nucleotide sugar, intracellular UTP and CTP pools fell to one third normal within 3 h after the administration of 1 mM pentaacetylglucosamine. At present it is unclear whether the cytotoxicity of beta-pentaacetylglucosamine or other similar agents is due to alterations in nucleotide and nucleotide-sugar pools causing a decrease in energy charge and polynucleotide biosynthesis or is due to a direct effect on membrane glycoconjugate biosynthesis.

Cell Division↗
PubMed1977

Drug uptake and ribonucleotide profiles of blast-enriched and blast-depleted human bone marrow cell populations.

A density cut method was used to prepare two subpopulations of bone marrow cells which were enriched (BE) and depleted (BD) respectively of blast cells. Marrow aspirates were obtained from 32 patients, 26 of whom had acute leukaemia. The uptake of a variety of chemotherapeutic agents by these two subpopulations and the acid-soluble ribonucleotide profiles of the populations were compared and significant differences were found in drug uptake by BE and BD subpopulations. For some drugs such as cytosine arabinoside, uptake was greatest by the BE cells, while for 5-azacytidine the BD subpopulation took up the greatest amount of the drug. The preparation of the BE subpopulation also permitted the recognition of several patients with acute leukaemia whose blast cells possess nondetectable levels of ATP, UTP, and GTP components in their acid-soluble fractions. The studies presented demonstrate the necessity of using purified cell populations when characterizing the drug uptake patterns and the soluble ribonucleotide profiles of the leukaemic cells. A simple method for enriching bone marrow aspirates for leukaemic cells is also presented.

Antimetabolites↗