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Biomedical subjects

A Papageorgiou

Publications and source records attributed to A Papageorgiou.

101 records · Page 6Linked to original sources
PubMedDate not supplied

Comparison of current alkylating agents with a homo-aza-steroidal ester for antineoplastic activity.

The modified steroidal alkylating agent, 17 beta-hydroxy-3-aza-A-homo-4 alpha-androsten-4-one-p-bis(2-chloroethyl)aminophenoxyacetate++ + has been tested against L1210 and P388 leukemias, and Lewis lung cancer, on DNA synthesis of EAT, L1210, P388, and BHK cell cultures, and on the induction of sister chromatid exchange. Comparable studies in vivo and in vitro were also done with p-bis(2-chloroethyl)aminophenoxyacetic acid, cyclophosphamide, melphalan, and chlorambucil.

Alkylating Agents↗
PubMedDate not supplied

Albumin possesses intrinsic enolase activity towards dihydrotestosterone which can differentiate benign from malignant breast tumors.

Serum albumin was found to possess enolase activity towards the dihydrotestesterone (DHT) molecule, converting it from its 3-keto to 3-enol form. This activity was accompanied by albumin during all stages of purification, as well as following various treatments, a fact indicating that the enzymatic activity was an intrinsic property of albumin molecule and did not represent an impurity of the preparation. Enolase activity was decreased in parallel with the quantity of intact albumin molecules when proteolytic enzymes were used for their degradation. The activity was strongly inhibited by Ni (II) and Cu (II) ions, which bind to 3-histidine of the albumin molecule, as well as by oleic acid and cholesterol. It was also inhibited, in a reversible manner by surface-active agents. Enolase activity was found in all mammalian species studied, the specific activity however was very low in the serum of dogs. The administration of DHT to mice did not influence the albumin or enolase levels in their serum. The optimum pH of enolase was at 9.2, with a carbonate buffer solution. In addition to the serum enolase activity was found to be a feature of intracellular albumin. The two albumins exhibited the same specific activity and the same Km for DHT. The study of cytosolic albumin, obtained from human mammary gland tissue, revealed that benign and malignant tumors of this gland differed substantially with respect to their percentage of albumin. Significant differences were also observed in enolase activity, a consequence of the existence of a fraction of albumin in the malignant tissue in a polymeric form. This form exhibited a decreased enzymatic activity, compared to its monomeric form, exclusively encountered in benign breast specimens. The last observation, along with the quantitative differences of albumin in the two tissues, offers a possibility of reliable differentiation between benign and malignant breast tumors.

Animals↗
PubMedDate not supplied

Synergistic antineoplastic and cytogenetic effects by the combined action of two homo-aza-steroidal esters of nitrogen mustards on P388 and L1210 leukaemias in vivo and in vitro.

In order to increase the damaging effects on specific DNA sequences and decrease the subsequent toxicity, the use of homo-aza-steroidal esters of nitrogen mustards is already known. Two specific homo-aza-steroidal esters were mixed at different proportions and the resultant final mixtures were tested in vivo and in vitro. The effects of these on P388 and L1210 leukaemias, on SCE rates and on human lymphocyte proliferation kinetics were studied. The results demonstrate that the combined substances enhanced SCE induction (p < 0.05) and antitumour activity (p < 0.02) in a synergistic manner. A correlation was observed (p < 0.001) between the magnitude of the SCE response and the depression of the cell proliferation index.

Animals↗
PubMedDate not supplied

Cytostatic effect of homo-aza-steroidal esters in vivo and in vitro. Structure-activity relationships.

The p-[N,N-bis (2-chloroethyl)amino]phenylacetate esters of 3 beta-hydroxy-N-methyl-17 alpha-aza-D-homo-5 alpha-androstan-17-one and 3 beta-hydroxy-17 alpha-aza-D-homo-5 alpha-androstane have been prepared and their antitumor activity evaluated against L1210 leukemia, P388 leukemia, Ehrlich ascites tumor (EAT) and Lewis Lung Carcinoma (LLC). The results are compared with those of the p-[N,N-bis (2-chloroethyl)amino]phenylacetate of 3 beta-hydroxy-17 alpha-aza-D-homo- 5 alpha-androstan-17-one. The above compounds were also tested in vitro against L1210, P 388, EAT and BHX cell cultures. All compounds were found to be active and their structure-activity relationship is discussed.

Androstanes↗
PubMedDate not supplied

Increased protective activity against acid precipitation of poly(U) in the serum of tumor-bearing mice.

Transplantation of leukemia L1210 cells into DBA/2 mice and of Ehrlich ascites tumor cells into BALB/C mice resulted in a significant increase of protective activity against acid precipitation of poly (U) in the serum. The increase was observed as early as one day after the tumor transplantation and seems to be connected with cancer growth, since inoculation of L1210 cells into BALB/C mice did not affect the protective activity, evidently as a result of their well established inability to cause cancer in this strain. Furthermore, no increase of activity was observed when bacteria were inoculated into mice, or when the latter were partially hepatectomized. The results suggest that the protective activity against acid precipitation of poly (U) could prove to be a tumor marker for the early detection of cancer growth.

Animals↗
PubMedDate not supplied

Potential antitumor agent: steroidal bilactam ester of p-N, N-bis (2-chloroethyl) aminophenylacetic acid.

7 alpha-, 17 alpha-Diaza-7, 17-dioxo-B, D-dihomo-5-androsten 3 beta-p-N, N-bis (2- chloroethyl)aminophenylacetate, a modified steroidal alkylating agent, is active in the treatment of P388 and L1210 leukemias in vivo. The compound was also tested in vitro against L1210 and P388 leukemias, on DNA, RNA and protein synthesis and showed high inhibition effect. Also increases the frequency of Sister Chromatid Exchanges and reduces the replication index of human lymphocytes.

Animals↗
PubMedDate not supplied

Antineoplastic and cytogenetic effects of complexes of Pd (II) with 4N-substituted derivatives of 2-acetyl-pyridine-thiosemicarbazone.

The effect of novel Pd(II) complexes with derivatives of 2-acetyl-pyridinethisemicarbazone, N4-ethyl (HAc4Et) and 3-hexamethyleneiminylthiosemicarbazone (HAchexim), on Sister Chromatid Exchange (SCE) rates and human lymphocyte proliferation kinetics was studied. Also, the effect of Pd(II) complexes on DNA synthesis of P388 and L1210 cell cultures and against Leukemia P388 was investigated. Among these compounds, the compound Bis(3-hexamethyleneiminyl-2-acetylpyridine-thisemicarbazonato++ +) palladium (II) was found to be distinctly effective against Leukemia P388, in inhibiting incorporation of 3H-thymidine into DNA and in inducing SCEs and cell division delays.

Animals↗
PubMedDate not supplied

Antitumor and cytogenetic effects of esteric (ASE) and amidic (ASA) steroidal derivative of p-bis (2-chloroethyl) amino phenylacetic acid (CAPA). A comparative study.

The homo-aza-steroidal ester of p-bis (2-chloroethyl) amino phenylacetic acid (ASE) (I) the homo-aza-steroidal amide of p-bis (2-chloroethyl) amino phenylacetic acid (ASA) (II), and the parent compound p-bis (2-chloroethyl) amino phenylacetic acid (III) were tested in an effort to evaluate their ability to inhibit a transplanted leukemia (P388) in vivo, and the DNA synthesis of P388 cell cultures in vitro. The compounds' effects on Sister Chromatid Exchange (SCE) rate and on human cell proliferation kinetics in vitro were also studied. The above mentioned compounds were identified as displaying cytogenetic, cytostatic and antineoplastic effects, the ester compound being the more potent. The main conclusion from this study is that the existence of the esteric bond is necessary for the expression of the antitumor activity. The synthetic route for the preparation of the amidic derivative (II), as new product, is also reported.

Animals↗