[Tumor microenvironment -  possibilities of the research under in vitro conditions]. / Mikroprostredí nádoru -  moznosti výzkumu v podmínkách in vitro.

Tumorigenesis is always accompanied by alterations of the microenvironment in the respective tissue. The tumor microenvironment represents a heterogeneous complex, in which cell proliferation, differentiation, necrosis or apoptosis are regulated by various extracellular stimuli, and it can also lead to development of an aggressive phenotype of tumor cells. Influence of tumor microenvironment is also often connected with resistance to frequently used therapeutic procedures. Specifics of the tumor microenvironment are closely associated with the structural and functional abnormalities of tumor microvessels and altered cellular metabolism. Moreover, changes such as increase in glycolysis, elevated glucose uptake, production of lactate and CO2, and presence of hypoxic regions and regions with acidic pH are typical features of tumor tissues. At present, there is a lot of methods for in vitro simulation and investigation of some of these specific conditions, and a number of new methods are being developed. A detailed understanding of the specifics of the tumor microenvironment should increasingly improve the development of new treatment possibilities of human cancers.

Anti-tumour necrosis factor-alpha activity in Ixodes ricinus saliva.

Tumour necrosis factor-alpha (TNF-alpha) is one of the most prominent inflammatory mediators playing a central role in starting off the inflammatory reactions of the innate immune system. We identified a TNF-alpha-inhibitory activity in the saliva and salivary gland extract (SGE) from partially fed Ixodes ricinus ticks. Using mouse and human TNF-alpha specific ELISA, we showed that tick saliva or SGE markedly reduced the level of detectable cytokine. Both saliva and SGE inhibited the cytotoxic effect of TNF-alpha in a bioassay. Elimination of the TNF-alpha-inhibitory activity in SGE by trypsin digestion demonstrated that the anti-TNF-alpha factor is a protein. Fast protein liquid chromatography fractionation of SGE showed one peak of TNF-alpha-inhibitory activity corresponding to a protein with estimated molecular mass 23 kDa. The likely mechanism of the inhibitory effect is a direct binding of the cytokine. The TNF-alpha-inhibitory molecule seems to play an important role in the anti-inflammatory effect of tick saliva at the tick feeding site, providing a gateway to the host for tick-borne pathogens.

[Diagnosis of beta-thalassemia on the basis of HbA2 determination]. / Diagnostika beta-talasémie na základe stanovení HbA2.

The increased level of HbA2 is a reliable marker of heterozygous beta-thalassaemia. The levels of HbA2 measured by three different methods were compared and the ranges for the normal and for the heterozygous beta-thalassaemia were assessed. The levels of HbA2 2.76 +/- 0.47% for normal (30 blood donors) and 4.62 +/- 0.77% for beta-thalassaemia (50 patients) were obtained by the chromatographic method 2.61 +/- 0.42% HbA2 for normal (30 blood donors) and 5.82 +/- 0.89% HbA2 for beta-thalassaemia (46 patients) were assessed by electrophoresis on hydragel (Sebia) and 2.8 +/- 0.62% HbA2 for normal (30 blood donors) and 6.04 +/- 0.96% HbA2 (47 patients) were found when using cellulose acetate electrophoresis. An increased level of foetal Hb was found in nine patients with beta-thalassaemia. The diagnosis of beta-thalassaemia was confirmed by molecular genetic methods in all cases with an elevated HbA2 level, while a normal HbA2 level did not rule out heterozygous beta-thalassaemia.

[New tests for laboratory diagnosis of spherocytosis]. / Nové testy pro laboratorní diagnostiku sférocytózy.

The authors evaluated advantages of the glycerol lysis test (AGLT) and its modification the "pink" test in the laboratory diagnosis of hereditary spherocytosis (HS). Both tests were positive in all examined subjects with HS and in some patients with autoimmune haemolytic anaemia (AIHA) and were negative in controls and some other haemolytic diseases. As these tests are easy to perform and quick, they can be recommended as a supplementary or screening examination in hereditary spherocytosis. The "pink" test has, as compared with the ALGT test, the advantage that it is simpler.

Organ distribution of fibrinogen-bound methotrexate in mice with Gardner lymphosarcoma.

The distribution of fibrinogen-bound 3H methotrexate was investigated in Gardner lymphosarcoma bearing mice. 3H labeled methotrexate (3H MTX) was covalently bound by means of aminopropyl carbodiimide to bovine and mouse fibrinogen (FBG). The preparations as well as the free 3H MTX were applied i.v. in a single dose to three groups of C3H mice on day 6 after the inoculation of Gardner lymphosarcoma. 3H MTX level was determined in the blood, spleen, tumor and liver. Sufficient amounts of MTX were released by proteolysis of FBG-MTX derivatives to induce chemotherapeutical effects. Protracted accumulation of MTX applied in the form of FBG-MTX derivatives was found in the spleen and in the liver, in contradistinction to free drug application, suggesting the proteolytic degradation as a directing step responsible for the prolonged persistence of FBG-MTX derivatives in the organs. In the tumor the highest amount of MTX was released from mouse FBG supporting the view of ready uptake of homologous FBG by tumors.

The effect of folate binding protein on the colony-forming activity of GM-CFC cells in vitro.

A modified method for the preparation of specific folate binding protein was described. The GM-CFC stimulating activity of this SFBP preparation was investigated on tissue cultures of human bone marrow cells. It has been found that in the presence of HPCM the cell proliferation was markedly increased by the SFBP. In the absence of HPCM, however, the cell proliferation has been influenced either positively or negatively presumably in dependence on the expression of folate receptors on the GM-CFC bone marrow cells.

Distribution and pharmacokinetics of methotrexate in localized chemotherapy of solid Gardner's lymphosarcoma.

Pharmacokinetics and organe distribution of Methotrexate (MTX) in Gardner lymphosarcoma bearing C3H mice was investigated following two ways of drug administration: 1. intraperitoneal injection, 2. intratumoral implantation of 2-hydroxyethylmethacrylate gel with sorbed Methotrexate (localized chemotherapy). The highest level of MTX in blood appeared 2 hours after intrperitoneal injection but 7 hr after localized intratumorous application. Following intraperitoneal application the drug level in tumor reached its maximum two hours after injection; after 7 hr the drug could not be detected any longer. The localized chemotherapy led to six times higher concentration of the drug in the tumors as compared with the intraperitoneal application. This high level persisted for 17 hr and decreased moderately for 48 hr. MTX was accumulated in liver after both modes of administration with a half life 6.1 hr after intraperitoneal injection and 12.4 hr after the localized chemotherpay, respectively.

Purification of thymidylate synthetase from enzyme-poor sources by affinity chromatography.

The adsorption of thymidylate synthetase from Escherichia coli B to aminoalkyl-Sepharose with the increasing length of carbon chain (2--6 carbon atoms) was investigated. A correlation was found between the chain length and adsorption effectiveness, increasing from the two- to the six-carbon chain. A hydrophobic chromatography of the enzyme on aminobutyl-Sepharose gave about 20-fold purification. A new affinity chromatography carrier was synthesized containing tetrahydromethotrexate linked to aminoethyl-Sepharose via its carboxylic groups. The carrier adsorbed the enzyme from the crude preparation only in the presence of deoxyuridine 5'-monophosphate (dUMP) in a concentration of 2 X 10(-5) M. The specifically adsorbed thymidylate synthetase was eluted with sacharose-containing buffers in which dUMP was omitted. The purification procedure was applied to a crude thymidylate synthetase preparation from resting E. coli, calf thymus, Sarcoma 180, and Gardner lymphosarcoma. The purified enzyme from all mentioned sources showed one protein band on disc electrophoresis corresponding to enzymatic activity. The formation of a reversible noncovalent complex enzyme-tetrahydromethotrexate-dUMP on the affinity column is supposed.