[Functional assays for detection of cancer stem cells]. / Funkcní testy pro detekci nádorových kmenových bunek.

Cancer stem cells (CSCs) are considered to be a population of tumor cells, which are responsible for tumor initiation and progression. They are also involved in metastasizing and may be a possible cause of multidrug resistance and tumor recurrence. CSCs possess the ability to self  renew and show a tumorigenic potential. Functional assays, which enable the detection of these properties, represent the main tool for identification of CSCs. This article summarizes both in vitro and in vivo methods used to identify the CSCs with emphasis on recently employed techniques of CSCs detection. In vivo tumorigenicity assay, sphere formation assay and colony  forming unit assay belong to the most commonly used functional assays. Further, label  retention assay and aldehyde dehydrogenase activity assay are described in this article.

Detection of cancer stem cell markers in sarcomas.

The identification of cancer stem cell markers represents one of the very relevant research topics because cancer stem cells play important roles in tumour initiation and progression, as well as during metastasis formation and in relapse of the disease. This article summarises recent knowledge on well-known and putative cancer stem cell markers in various types of bone and soft-tissue sarcomas. Special attention is paid to the detection of CD133, ABC transporters, nestin and aldehyde dehydrogenase that have been intensively studied both in tumour tissues and in sarcoma cell lines during the past few years. Finally, an overview is given of the possible CSC phenotypes provided by functional assays of tumourigenicity.

Reversed-phase high-performance liquid chromatography of ionogenic compounds: comparison of retention models.

Two kinds of retention models describing a behaviour of ionogenic substances in reversed-phase chromatographic systems were compared. Model A utilises a concept of limiting retention factors and is especially suitable for the prediction of retention of compounds co-existing in several forms in mobile phase. An effect of the concentration of organic modifier (e.g., methanol) on the magnitudes of the limiting retention factors and equilibrium constants (dissociation constants of the separated substances) can be expressed with the aid of various, more or less sophisticated, relationships. A stoichiometric displacement model (model B) in its original form simply relates the analyte retention to the content of organic modifier in the mobile phase. In this work, it was modified to also express an effect of the mobile phase pH introducing side equilibria (acid-base) into the model. Both models predict a sigmoidal dependence of the analyte retention factor on the mobile phase pH in accordance with experimental data, and allow, among others, to estimate dissociation constants from those data. Experimental dependencies between the analyte retention and the concentration of methanol in the mobile phase comply well with model A, whereas the stoichiometric displacement model could be used only in a limited range of the methanol concentrations.

Smoking during pregnancy and the perinatal cadmium burden.

The association between maternal smoking and both morphometric birth parameters and the perinatal cadmium burden were studied. The cadmium concentrations were measured by atomic absorption spectrometry in 100 samples of maternal whole blood (MB) and in 93 samples of umbilical cord blood (CB). In the group of nonsmokers, significantly higher birth weight and decreased relative placental weight were noted as compared to the group of smokers who smoked more than 6 cigarettes a day (p less than 0.05). In both maternal and cord blood samples, the measured Cd levels were found to be significantly higher in smokers than in the nonsmoking subjects (for MB and CB p less than 0.01 and p less than 0.01 respectively). The average number of cigarettes smoked daily by the women had little effect on the levels of the metal. The Cd-MB strongly correlated with the Cd-CB (p less than 0.001). The cadmium values determined in MB and CB did not significantly affect any of the studied fetoplacental parameters. The reported findings give support for placental permeability to cadmium in humans and confirm that smoking during pregnancy leads to elevated Cd concentrations in both the mother and the fetus.

PIP: 100 healthy parturients and 100 neonates born to them between 37-42 weeks of pregnancy in the Institute of Obstetrics and Gynecology in Lublin, Poland, participated in an investigation designed to demonstrate whether smoking during pregnancy alters the perinatal cadmium burden and, if so, what influence this may have on morphometric fetoplacental parameters. 37 women did not smoke during pregnancy; the remaining 63 were current smokers. The median value of the number of cigarettes smoked daily was 6. The smoking group was divided into 2 subgroups: smokers who smoked 6 or less cigarettes per day and those who smoked more than 6 cigarettes per day. None of the differences calculated for mean age, parity, and the duration of pregnancy between the subgroups of women studied was statistically significant. The mean birth weight of the neonates born to nonsmoking mothers was significantly higher than that of the group smoking less than 6 cigarettes per day. The mean placental weight in the nonsmokers was higher than in both subgroups of smokers, but these differences were insignificant. When relative placental weight was evaluated, the difference between the group smoking more than 6 cigarettes per day and the nonsmokers appeared to be statistically significant. A slight insignificant decrease in Roher's ponderal index was observed in the newborns of smoking mothers as compared to the infants of nonsmokers. Detectable cord (Cd) concentrations were found in 27.0% of the blood samples obtained from nonsmoking mothers and in 32.4% of umbilical cord blood (CB) samples obtained from their neonates while in the smoking group detectable maternal blood (MB) and CB cadmium levels were measured in 61.9% and 57.1% of samples respectively. These differences were statistically significant. The average number of cigarettes smoked per day by the women had little effect on the measured metal levels. There was a markedly significant correlation between MB and CB cadmium levels. In 19.4% of cases, Cd-CB exceeded the corresponding MB value. The direction of the transplacental gradient for cadmium as estimated by the sign test was statistically insignificant. None of the fetoplacental parameters studied was significant associated with cadmium levels in MB and CB. The study results confirm that the physical development of newborns with fetal tobacco syndrome is retarded in comparison to the neonates of nonsmoking mothers.

Azapyrimidine nucleosides: metabolism and inhibitory mechanisms.

Triazine nucleosides represent highly active compounds affecting different cellular processes. While 6-azauridine displays a rather selective inhibitory effect, biological action of 5-azacytidine reflects the polyvalent inhibitory mechanism of the drug (interaction with pyrimidine synthesis de novo, incorporation into RNA and DNA, depressed maturation of ribosomal RNA, inhibition of RNA and DNA methylation, etc.) and the analog displays pronounced cytostatic and immunosuppressive activity. 5-Aza-2'-deoxycytidine action is directed against DNA synthesis similar to that of 5-azacytosine arabinoside. N4-Substituted derivatives of 5-azacytidine affect gastric secretion and together with 5-azacytosine and 5-azacytidine represent a new type of drugs with antiulcer activity. 6-Amino-5-azacytosine nucleosides interfere with the metabolism of purines rather than pyrimidines as evidenced by the character of their inhibitory mechanism and measurement of conformation. 6-Azauridine (as 2',3',5'-triacetate) and 5-azacytidine were used with certain success in human chemotherapy, the first one as a drug affecting recalcitrant psoriasis, the second one for the treatment of different forms of leukemia. The inhibitory mechanisms of individual azapyrimidine nucleosides are discussed in relation to their known biological effects.

Inhibitory effect of 5-bromo-6-azauracil on growth and cell division of Saccharomyces cerevisiae.

The most marked effect of 5-bromo-6-azauracil (BrAzU) on yeast cells is to cause cell lysis. The inhibition of the lytic process is delayed and this delay coincides in time with the capacity of preformed pyrimidines to reverse the effect of BrAzU.

An all-metal block for replica plating of microbial colonies.

The surface of a metal block made of an aluminium alloy is covered with narrow perpendicular grooves, which thus form an array of quadrangular pyramids touching base to base. The surface is further provided with a marker which assures the positioning of the master plate and the replica plate. Replicas prepared using this block are of higher quality than those using the velveteen-covered cylinder. A single master plate will provide ten or more replicas of good quality, the master plate being preserved for further work. Last but not least, the all-metal block can be easily cleaned and heat-sterilized.

Some cytostatic and pharmacological properties of 2,3-dihydro-1,3-6H-oxazine-2,6-dione ("3-oxauracil").

Cytostatic effects and some pharmacological properties of a new metabolic inhibitor "3-oxauracil" were studied. The cancerostatic effect was examined on 7 experimental tumors in mice and on two types of tumors in rats. After the i. p. application of 20 mg/kg, there was both a statistically significant decrease of tumor weight and increase of animals' survival time in NK lymphoma of mice. Significant changes in one of both parameters followed occured in all experimental tumors after the i. p. application but only in the Krebs ascitic carcinoma after the oral application of "3-oxauracil". The acute toxicity of the substance in water was 322 mg/kg i. p. and 850 mg/kg p. o. The ethanol solutions were more toxic. The distribution of the 3H- and 14C-labeled substance was followed up in blood, urine, liver, brain and kidney. After the p. o. application, the radioactivity peak was reached after 2 hr in blood and high radioactivity levels were found in kidney followed by brain and liver. 96 hr after the drug was applicated perorally, only 60% of radioactivity was found in urine.

Effect of "3-oxauracil" (2,3-dihydro-1,3-6H-oxazine-dione) in L1210 leukemia.

2.3-Dihydro-1,3-6H-oxazine-dione ("3-oxauracil") was tested against L1210 leukemia. The compound exhibited significant growth-inhibiting effect against this tumor both in vitro and also in vivo following daily intraperitoneal application.