[Malignant tumors of the appendix and small intestine in a 10-year study of case material of our hospital].
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Adult↗
Biomedical subjects
D Gaál
Publications and source records attributed to D Gaál.
A multifactorial system controlling myeloid cell differentiation and division.
It has been demonstrated that mature granulocytes contain two stimulatory and three inhibitory factors of cell proliferation. Consequently, beyond the negative feedback inhibitor (chalone), myeloid cells are controlled presumably by other negative (inhibitory) and positive (stimulatory) mechanisms, in addition.
Animals↗
Modulative effect of endogenous granuloid inhibitors on cell proliferation.
The particle-free crude extract of differentiated granulocytes (GCE) and the GI-1, GI-2, GI-3 proliferation inhibitory fractions (M.W. larger than or equal to 70,000 approximately 11,500 and less than or equal to 4000) were studied for the effects they exert on cultured cells. As shown by the curve, in bone marrow suspension cultures, in the dose range of 0.01-10.0 microng/ml, GCE maximally inhibits 3H-TdR incorporation into the DNA for 5.5 hours. In agar-gel cultures, 1.0-5.0 microng/ml of GCE reduces both the number (by 50.6-54.8%) and the size of the colonies formed. The manifestation of the inhibitory effect of GI-1, GI-2 and GI-3 fractions requires 2.5-3.5 hours. The inhibitors designated GI-2 and GI-2 are target-cell specific but they do not reduce 3H-TdR incorporation either in thymocyte suspension or HeLa monolayer cultures. On the other hand GI-1 inhibis the proliferation in HeLa cultures, as well. These endogenous inhibitors exert their optimum effect, even in a partially purified state at 2-4 orders or magnitude lower concentrations than does 1,2/5,6-dianhydrogalactitol (DAD), a cell-aspecific inhibitor used for comparison in the same system.
Alkylating Agents↗
Carrier design: new generation of polycationic branched polypeptides containing OH groups with prolonged blood survival and diminished in vitro cytotoxicity.
For the construction of macromolecule-drug conjugates, it is important to provide rational basis to the selection of proper carrier. With respect to the importance of the side-chain structure and charge of the branched polypeptides in biological properties, we have prepared a new class of branched polypeptides with single or multiple hydroxyl groups and studied their solution conformation, in vitro cytotoxicity, biodistribution, and immunoreactivity. For comparative studies, polypeptides were designed to contain serine at various positions of the side chains, varying also the number. Ser was attached to the end of oligo(DL-Ala) side chains grafted to polylysine resulting polypeptides with the general formula poly[Lys(Ser(i)-DL-Ala(m))], (SAK). Ser was also coupled directly to the polylysine backbone poly[Lys(Ser(i))] (S(i)K) and then elongated by polymerization of N-carboxy-DL-Ala anhydride resulting poly[Lys(DL-Ala(m)-Ser(i))] (ASK). An additional polymer was also prepared, but instead of the oligo(DL-Ala) branches, oligo(DL-Ser) side chains were introduced (poly[Lys(DL-Ser(m))], SK). The presence of hydroxyl groups resulted in compounds with improved of water solubility. CD spectra of polypeptides showed significant differences correlating with the position and numbers of Ser residues in the side chains. Under physiological conditions, polycationic polypeptides assumed ordered secondary structure (S(i)K and LSK) or partially unordered conformation (SK, SAK, and ASK). Data of selected polymers demonstrate that these polycationic compounds are essentially nontoxic in vitro on normal rat liver or mouse spleen cells and have no cytostatic effect on mouse colorectal carcinoma C26 cells. The blood clearance and biodistribution of these derivatives were greatly dependent on the position and number of Ser residues in the branches and possess a rather extended blood survival in mice. Polypeptides were taken up predominantly by the liver and kidney (S(i)K, LSK, and ASK) or kidney and lung (SK and SAK). The best survival in the blood was found with SAK, representing the first polycationic branched polypeptide, which show extended blood clearance. The relative position of Ser residue had also a marked influence on the immunogenicity of polypeptides. The characteristics of the antibody response to polypeptide containing Ser at the end of the branches (SAK) or adjacent to the polylysine backbone (ASK) was also dependent on the genetic background of the mouse strains. We also found that these compounds have no effect on to the SRBC-specific humoral immune response, indicating the lack of nonspecific immunostimulatory potential. In conclusion, these studies suggest that synthetic branched polypeptides with Ser can be considered as candidates for constructing suitable conjugates for drug/epitope delivery. It is not only due to the presence of hydroxyl group to be used for oxime chemistry but also to their beneficial biological features.
Adjuvants, Immunologic↗
Growth inhibitory effect of the somatostatin structural derivative (TT-232) on leukemia models.
TT-232 is a structural derivative of the natural signal inhibitory peptide somatostatin, with selective antiproliferative and anti-inflammatory properties. TT-232 activates SSTR receptors (primarily the SSTR-1), which leads to irreversible cell cycle arrest, followed by secondary induction of apoptosis. TT-232 has passed phase I clinical trials without toxicity and significant side-effects. We examined the antiproliferative effect in vitro and the antitumor effect in vivo of TT-232 on leukemia cell lines. During in vivo experiments, we evaluated the therapeutic efficacy of TT-232 in various long-term administration routes; traditional injection versus infusion treatment via an inserted Alzet minipump on P-388 mice and HL-60 human leukemia models. Treatment with TT-232 started after development of the disease. In vitro, TT-232 inhibited the proliferation of P-388 mice lymphoid cells and HL-60 human promyelocytic leukemia cells in the range of 46%-97% with 24-hour treatment and 82%-100% with 48-hour treatment. Cells were treated with 30 microg/ml and 60 microg/ml dose of TT-232. With the same in vivo models, the best results were achieved when TT-232 was applied by infusion treatments. The infusion treatment with TT-232 produced 50%-80% inhibition of growth and resulted in 20%-40% long-term and leukemia-free survivors. TT-232 showed dose-, time- and administration mode-dependent antileukemia activity in vitro and in vivo, both on rodent and human models. Our results suggest that TT-232 is a promising new antileukemia agent.
Animals↗
A comparison of the tumor growth inhibitory effect of intermittent and continuous administration of the somatostatin structural derivative TT-232 in various human tumor models.
The tumor growth inhibitory efficacy of the somatostatin structural derivative TT-232 was studied using different routes of administration and treatment schedules in various human tumor models. TT-232, containing a five-residue ring structure, has a strong antitumor activity both in vitro and in vivo. The antineoplastic activity of TT-232 has been found to be associated with the induction of programmed cell death in tumor cells, resulting in highly-selective elimination of the neoplastic tissue. The study compared the antitumor efficacy of TT-232 in various long-term administration routes; the intermittent (injection) versus continuous (infusion) treatment via subcutaneously-inserted Alzet osmotic minipumps in different human tumor models: T-47/D human breast carcinoma and A-431 human epidermoid carcinoma. Treatment with TT-232 started after disease development. The antitumor activity of TT-232 was evaluated on the basis of the tumor growth inhibition. In the case of T-47/D human breast carcinoma, the intermittent treatment resulted in 23%-26% and the infusion treatment resulted in 48%-53% tumor growth inhibition. The tumor growth inhibitory effect of TT-232 on A-431 human epidermoid carcinoma tumor resulted in 35%-43% (intermittent treatment) and 70%-74% (continuous treatment) decreases in tumor volume. This antitumor efficacy of TT-232 was observed in the two human tumors investigated. In this study, the route of infusion was shown to increase drug efficacy relative to conventional delivery methods. The results suggest that TT-232 is an effective and promising antitumor agent.
Animals↗
Evaluation of the antitumor efficacy of the somatostatin structural derivative TT-232 on different tumor models.
The antitumor effects of the somatostatin structural derivative TT-232 in different rodent and xenograft tumor models are summarized in this report. TT-232 had previously been shown to inhibit the proliferation of a large number of cancer cell lines in vitro and reduce the size of different tumors in animal models in vivo. The effects of TT-232 by different routes of administration and treatment schedules were studied in various types of rodent and human xenograft tumor models. In the rodent tumor models S-180 sarcoma and P-388 lymphoid leukemia tumor the infusion treatment resulted in 76%-100% tumor growth inhibition and in 20%-60% of the mice being long-term and tumor-free survivors. In the aggressive C-26 colon carcinoma and MXT breast carcinoma, the TT-232 treatments resulted in 71%-75% tumor growth inhibition and an approximately 50% increased survival time. The tumor growth inhibitory effect of TT-232 on human tumor xenografts proved to be significant, resulting in 30%-80% decrease in tumor volume and in 20%-40% tumor-free animals. This antitumor efficacy of TT-232 was seen in almost all the tumors investigated. In our study, the route of infusion was shown to increase drug efficacy relative to conventional delivery methods. Our results suggested that TT-232 is an effective and promising antitumor agent.
Animals↗