Modeling Cell Reactions to Ionizing Radiation: From a Lesion to a Cancer.

This article focuses on the analytic modeling of responses of cells in the body to ionizing radiation. The related mechanisms are consecutively taken into account and discussed. A model of the dose- and time-dependent adaptive response is considered for 2 exposure categories: acute and protracted. In case of the latter exposure, we demonstrate that the response plateaus are expected under the modelling assumptions made. The expected total number of cancer cells as a function of time turns out to be perfectly described by the Gompertz function. The transition from a collection of cancer cells into a tumor is discussed at length. Special emphasis is put on the fact that characterizing the growth of a tumor (ie, the increasing mass and volume), the use of differential equations cannot properly capture the key dynamics-formation of the tumor must exhibit properties of the phase transition, including self-organization and even self-organized criticality. As an example, a manageable percolation-type phase transition approach is used to address this problem. Nevertheless, general theory of tumor emergence is difficult to work out mathematically because experimental observations are limited to the relatively large tumors. Hence, determination of the conditions around the critical point is uncertain.

THE UNKNOWN SHADOWS OF TREHALASE.

Each year brings new facts concerning multiple roles of sugar pathways in plant metabolism. One of them--the trehalose pathway--has been shown to play a role in stress signalling. The last enzyme of this pathway--trehalase--has been proven to be strongly expressed in guard cells. Modifications of its abundance cause changes in stomatal closure and response to abscisic acid. Our phenotypical studies of different mutants of Arabidopsis thaliana and Musa have enabled us to propose a new function of trehalase. It might play a role in the feedback of sucrose as a closing signal for stomata in reaction to an efficient photosynthesis. To characterize the phenotype we measured: the dynamic cumulative water loss, the dynamic leaf surface temperature, and the stomatal conductance. Based on the obtained results we have determined the time points for a proteomics study. The exact role of trehalase and related proteins in the proposed mechanism will be defined with multiple analysis including mass spectrophotometry and enzymatic activities. The samples will be collected from a wide type of plants including model organism (Arabidopsis--wild type, trehalase mutant plants) and crops (banana). The final results will shed light on the complete role of trehalase and the feedback pathway.

Uridine--an indicator of post-exercise uric acid concentration and blood pressure.

Studies have shown that uridine concentration in plasma may be an indicator of uric acid production in patients with gout. It has been also postulated that uridine takes part in blood pressure regulation. Since physical exercise is an effective tool in treatment and prevention of cardio-vascular diseases that are often accompanied by hyperuricemia and hypertension, it seemed advisable to attempt to evaluate the relationship between oxypurine concentrations (Hyp, Xan and UA) and that of Urd and BP after physical exercise in healthy subjects. Sixty healthy men (17.2+/-1.71 years, BMI 23.2+/-2.31 kg m(-2), VO(2max) 54.7+/-6.48 ml kg(-1) min(-1)) took part in the study. The subjects performed a single maximal physical exercise on a bicycle ergometer. Blood for analyses was sampled three times: immediately before exercise, immediately after exercise, and in the 30th min of rest. Concentrations of uridine and hypoxanthine, xanthine and uric acid were determined in whole blood using high-performance liquid chromatography. We have shown in this study that the maximal exercise-induced increase of uridine concentration correlates with the post-exercise increase of uric acid concentration and systolic blood pressure. The results of our study show a relationship between uridine concentration in blood and uric acid concentration and blood pressure. We have been the first to demonstrate that a maximal exercise-induced increase in uridine concentration is correlated with the post-exercise and recovery-continued increase of uric acid concentration in healthy subjects. Thus, it appears that uridine may be an indicator of post-exercise hyperuricemia and blood pressure.

Blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training.

The aim of this study was to evaluate response of blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training. Nine untrained trotters (aged 16-20 months) were exposed to a 4-month training program based on exercises at low-to-moderate intensity. The conditioning consisted of breaking the horses and running them on distances varying from 4 to 40 km a week. The workloads were increased on a 3-week basis. Exercise intensity was monitored by measuring heart rate and blood lactate. Blood samples were collected at rest, before (RES0) and after (RESt) the conditioning period; moreover, on the latter occasion (on day 112 of training), the blood was also taken immediately after the routine exercise (EXE0) and 60 min thereafter (EXE60). The whole blood samples were analysed for the concentration of reduced, oxidized and total glutathione (GSH, GSSG and TGSH, respectively), while the activities of glutathione peroxidase (GPX) and glutathione-disulfide reductase (GR) were determined in haemolysates. Additionally, the erythrocytic concentrations of oxidized nicotinamide adenine dinucleotide (NAD(+)) and its phosphate (NADP(+)) were measured. All investigated parameters except NAD(+) and reduced/oxidized glutathione ratio (GSH/GSSG) changed during the training period. Following the effortm GPX, NADP(+) and GSH/GSSG were significantly lower (p < 0.05, p < 0.01, p < 0.001, respectively) while GSSG was markedly higher than at rest (RESt). The drop in NADP(+), low GSH/GSSG and high GSSG concentration were sustained at EXE60. Glutathione-disulfide reductase activity was higher after the workout but only at EXE60 the increase in activity was significant. Despite the activities of the GSH-GSSG cycle, enzymes were considerably higher after the training period, the elevated concentration of GSSG and significantly lower GSH/GSSG ratio in the post-exercise measurements suggest that production of reactive oxygen species possibly exceeds the capacity of antioxidative defenses of immature trotters. A more balanced diet with additional antioxidant supplementation and a revision of the basic training protocol used herein are advised.

[Environmental radiation exposure of a thyroid cancer patient resulting from adjuvant iodine radiotherapy]. / Narazenie radiacyjne otoczenia chorego na raka tarczycy w wyniku uzupelniajacego leczenia jodem promieniotwórczym.

The aim of the study was to evaluate radiation risk in the environment of patients treated with 131I as an ablative therapy following radical surgery for the differentiated thyroid cancer. The activities of radioiodine used in this form of therapy approximate 2.8 GBq (76 mCi) and the in cases of the cancer metastases to other organs may be as high as 7.4 GBq (200 mCi). Dose equivalent rates were estimated in nine seated patients at the level of the thyroid close to the gland surface, and 0.5 and 1 m away from it. The measurements were performed at one, 24, 48, 72, 96, 120, 144, and 168 hours after the injection of 131I. The dose equivalent rates at various distances from the thyroid surface at different times were approximated with the exponential function by the least square method. Then, the dose equivalents were calculated from the moment of 131I application to the moment of the total removal of the isotope from the organism. From this relation, time intervals after which the annual threshold doses of 1, 5, and 50 mSv would be exceeded were computed as the function of the applied 131I activity. The results of the present study indicate that attendants of the patients treated with 131I will not be exposed to the doses of ionising radiation exceeding the acceptable annual thresholds provided with the limited time intervals. In addition, the present results may be useful in elaborating procedures of dealing with and handling the patients during their stay at hospital, at home, and at work.

New cytokine dressings. I. Kinetics of the in vitro rhG-CSF, rhGM-CSF, and rhEGF release from the dressings.

Wound repair-stimulatory activities of various cytokines and growth factors depend on successful delivery of these factors to the injured sites. Here were present the design and preparation of the new collagen- and polyurethane-based dressings containing the recombinant human cytokines-rhG-CSF, rhGM-CSF or rhEGF. To test the efficacy of the retrieval of the incorporated cytokines, their controlled release from the dressings was carried out over three consecutive days using polyurethane sponge as a collector of the extracts. The maximum quantities of the released rhG-CSF, rhGM-CSF and rhEGF reached approximately 25, 50, and 10%, respectively, of the total cytokine contents of the dressings, as assessed by the specific ELISA tests. These data indicate that collagen- and polyurethane dressings containing rhGM-CSF and rhG/CSF may serve as effective tools for the topical delivery of cytokines to wounded tissues.

New cytokine dressings. II. Stimulation of oxidative burst in leucocytes in vitro and reduction of viable bacteria within an infected wound.

Recently, we have developed the new dressings containing rhG-CSF or rhGM-CSF. In the present study we investigated either in vitro or in vivo biological activity of the dressings. Human whole blood samples were incubated with extracts from the collagen- or polyurethane-based dressings containing rhG-CSF or/and rhGM-CSF and phagocytic and oxidative metabolic activities were quantitated using Phagotest or Bursttest kits. The results indicate that both the number of phagocyting cells and the intensity of phagocytosis per cell, as well as the level of the oxidative burst in particular, were stimulated by one or both of the cytokines extracted. Next, the experimental skin wounds in mice were infected with 107 CFU of Pseudomonas aeruginosa strain ATCC 27853 and treated locally with the rhG-CSF-containing dressing. The analysis of the biopsies taken from the wounds indicated that in mice treated with the cytokine-containing dressing on the third day the log of CFU per biopsy was 5.0 vs. 6.2 in the control (P<0.001), and on the 8th day was lower than 4 vs. 5.4 in control (P<0.0001). Our findings clearly suggest that the newly designed dressings containing the incorporated CSFs can be used as effective topical cytokine-delivery system in the treatment of bacterial infections in wounds.

[Local application of G-CSF, GM-CSF and EGF in treatment of wounds]. / Miejscowe stosowanie cytokin G-CSF, GM-CSF oraz EGF w leczeniu ran.

G-CSF, GM-CSF and EGF play an important role in wound healing as components of the cytokine network which regulates cooperation of cells in the repair processes. The first two cytokines have been registered as hematopoietic drugs under the names Neupogen (Roche) and Leucomax (Sandoz). Both G-CSF and GM-CSF stimulate phagocytosis in maturated leucocytes and enhance proliferation of endothelial cells. G-CSF, GM-CSF and EGF which is known as mitogenic agent were applied as topical drugs for wound care; the application resulted in acceleration of wound healing. Preliminary suggestions as to the topical dosage of the cytokines in the treatment of wounds are put forward.

Expression of beta 1 integrin mRNAs in human leukemic blasts.

Adhesion receptors from the very late activation (VLA) (beta 1) integrin subfamily play a role in the cooperation of hematopoietic progenitors with bone marrow stroma, and the disregulated expression of these molecules, as evaluated by immunophenotyping, has been implicated in the acquisition of the malignant phenotype by hematopoietic cells. In the present study, Northern hybridization was used to determine the pattern of expression of transcripts for VLA subunits in: (i) leukemic blasts obtained from the peripheral blood of ten patients with acute myelogenous leukemia (AML) of different FAB subclasses; (ii) the human leukemic cell lines KG-1, HL-60, K-562, HEL and U-937; and (iii) normal hematopoietic cells. Most of the AML blasts and the cultured leukemic cells expressed mRNAs for the beta 1 and alpha 5 subunits (the only exception among the cell lines was KG-1 cells) and these transcripts were also found in normal bone marrow progenitors, peripheral blood mononuclear cells (PBMNC), and peripheral blood monocytes. While the alpha 4 transcript was detected in all cultured cells but K-562, and in normal circulating monocytes, it occurred in blasts from only two AML patients and was weakly expressed in mature PBMNC. No specific pattern of expression of beta 1, alpha 5, and alpha 4 transcripts could be related to cell differentiation or maturation in the AML blasts and leukemic cell lines tested. None of the primary AML blasts or cultured cells showed mRNA messages for alpha 2, alpha 3 or alpha 6 chains of the beta 1 integrins. The results suggest that, in some cases of AML, the malignant phenotype of leukemic blasts may be associated with down-regulated transcription of the alpha 4 integrin subunit.

Use of the Matrigel-based assay to measure the invasiveness of leukemic cells.

The reconstituted basement membrane (Matrigel)-based assay was used to quantify the invasive potential of hematopoietic cells including cultured human leukemic cells (KG-1, K-562, HEL, HL-60, and U-937), normal bone marrow (BM) cells, and normal polymorphonuclear leukocytes (PMNL). We found that (i) in contrast to 6- to 72-hour incubation periods typically used in assays with solid tumor cells, most of the invasive cell populations tested here required only 2 to 4 hours to cross the Matrigel layer; (ii) unlike that of PMNL, whose invasiveness was stimulated by the addition of FMLP, the invasive rate of cultured leukemic cells was not affected by this chemoattractant; (iii) the rate of invasion was inversely proportional to the Matrigel concentration per filter but varied with the Matrigel batch used; (iv) the most consistent results were obtained when 2.5 to 4 x 10(5) cells were added to the top portion of the blind well; and (v) of all leukemic cells tested, the least differentiated myeloblastic KG-1 cells exhibited the highest invasive potential, which was comparable to that of normal PMNL. We conclude that the Matrigel-based assay can be used as a model system in studies of mechanisms regulating movement of hematopoietic cells across basement membrane barriers.

Recombinant tumor necrosis factor alpha inhibits growth of methylcholanthrene-induced sarcoma and enhances natural killer activity of tumor-infiltrating lymphocytes in aging rats.

The effect of recombinant human tumor necrosis factor alpha (rHuTNF-alpha) on the growth of immunogenic, methylcholanthrene-induced sarcoma (MC-Sa) and natural killer (NK) cell activity of tumor-infiltrating lymphocytes (TIL) in adult and aging rats was investigated. In both groups of animals the growth of transplantable MC-Sa was markedly and similarly inhibited by multiple intratumoral (i.t.) injections of rHuTNF-alpha. This effect was accompanied by stimulation of NK activity of tumor-infiltrating lymphocytes in adult as well as in aging rats. Studies in vitro demonstrated additionally that rHuTNF-alpha was a potent stimulator of NK but not of ADCC (antibody-dependent cellular cytotoxicity) activity of spleen lymphocytes from healthy animals. Our results indicate that the antitumor effect of TNF-alpha is comparable in adult and in aging rats bearing immunogenic MC-Sa. The inhibition of MC-Sa growth may be attributed not only to the TNF-alpha-induced necrosis of the neoplastic tissue but also to the in vivo stimulatory effect of this cytokine upon the NK-type function of lymphocytes infiltrating the tumor mass.

Activity of natural killer (NK) cells in the course of experimental trichinellosis in mice.

B6C3F1 mice were infected with 200 or 500 larvae of Trichinella spiralis per mouse and pulmonary NK cell-mediated clearance of semisyngeneic tumour cells was determined in vivo on days 10, 20, 30, and 60 after the infection. Cytotoxic activity of NK cells in the lungs was substantially elevated on days 20 and 30 after challenge with both "doses" of the parasite. At the same time large granular lymphocytes (LGLs) as well as cells expressing surface asialo-GM1 molecules were isolated in elevated numbers from spleens of the infected as opposed to the normal mice. Expression of other markers of differentiation, such as THy 1, CD4, and CD8 was also enhanced on splenocytes isolated from the infected mice on day 30 but not 20 after administration of the larvae. The present results indicate that NK cell-mediated activity in vivo is stimulated above the baseline level during migration and early muscle phases of the infection with T. spiralis in mice. The possible impact of this effect upon the course of trichinellosis as well as upon the growth of tumours in the infected host is discussed.

[Activity of natural killer cells (NK) in patients with atopic diseases of the respiratory system]. / Aktywnosc komórek NK u chorych z chorobami atopowymi ukladu oddechowego.

NK cells are one of the crucial elements of natural cellular immunity mechanisms in situations when specific mechanisms are not altered. The aim of this study was to study activity of such cells in atopic respiratory diseases. The study was carried out in 52 atopic patients; 37 had atopic respiratory diseases, 15 atopic dermatitis. Control consisted of 28 healthy subjects without a history of atopy. Effector lymphocytes were recovered after centrifugation on the Ficoll/Uropolin gradient from venous blood. The activity of NK cells was determined using the cytotoxic test studying the level of emitted 51Cr from a standard K562 cell line. The authors have shown that the activity of NK cells is increased but this does not correlate with the level of IgE. This was seen mostly in patients with atopic respiratory diseases. In subjects with atopic dermatitis the activity of NK cells was similar to the seen in control subjects.

Suppression of the activity of natural killer-like cells by peritoneal macrophages obtained from Lewis lung tumor-bearing, Propionibacterium granulosum KP-45-treated, or normal, untreated mice.

Peritoneal adherent cells (PAC) obtained from Propionibacterium granulosum KP-45-treated or Lewis lung carcinoma-bearing BDF1 mice suppressed in vitro the NK-like cytotoxic activity of murine splenocytes against YAC-1 tumor target cells. Maximum inhibition occurred when suppressor and effector cells were preincubated together for 18 h, but the effect was demonstrable also when the two groups of cells were mixed only at the onset of the 4-h cytotoxic assay (i.e. without previous contact). Inhibitory cells appeared to be mostly macrophages, as judged by adherence to plastic and morphologic features, and as little as 5 to 20% of PAC, relative to the total number of co-incubated cells, were required for the clear demonstration of the effect. In addition to activated also normal, resident PAC obtained from untreated animals inhibited the NK cell-mediated cytotoxicity, but the effect was significantly pronounced only when 20% of suppressor cells were incubated overnight with effector splenocytes. The results favor the hypothesis that both functionally activated as well as resting macrophages operate as important regulators of the activity of NK cells in vivo.

Stimulatory effect of Propionibacterium granulosum KP-45, glucan and pyran copolymer on the activity of natural killer (NK) cells in murine lungs.

Propionibacterium granulosum KP-45, glucan and pyran copolymer stimulated the elimination of 75Selenomethionine-labelled 3LL tumor cells from murine lungs, as measured 4 hr after intravenous injection of these cells into 16- to 25-week-old B6DF1 mice. This effect was most pronounced 4 to 6 days following intravenous administration of the above biological response modifiers and disappeared 6 to 8 days later. Intraperitoneal injection of all three agents produced only insignificant stimulation results. Spontaneous clearance of 3LL cells from lungs of 8-week-old B6DF1 mice was significantly more effective than in animals over 16 weeks old. Cyclophosphamide suppressed the elimination of tumor cells from lungs in both young and older mice and neutralized the stimulatory effect of P. granulosum KP-45 and glucan. The results suggest that the effector cells responsible for the clearance of radiolabelled 3LL cells from lungs of B6DF1 mice are at least similar to natural killer (NK) lymphocytes.

Effects of microwave exposure in utero on embryonal, fetal and postnatal development of mice.

Pregnant Swiss mice were repetitively exposed during various periods of gestation to 2,450 MHz continuous wave microwave radiation. Irradiations were conducted daily in an anechoic chamber at a power density of 10 (subthermal) or 40 mW/cm2 (thermal) for 2 h/day, 7 sessions/week. Thermal exposures to microwaves resulted in significant inhibition of the embryonal and fetal development in utero, accompanied by an increased incidence of intrafetal bleedings, resorptions and deaths of fetuses. Moreover, nonspecific resistance to viral and bacterial infections was markedly depressed in pups of dams irradiated for the whole period of gestation with thermal doses of microwaves. No such effects were found following exposure of pregnant mice to 10 mW/cm2 power density of radiation. The results suggest that the observed effects of microwave exposure in the course of pregnancy are thermal in nature.

[Development of murine embryos and fetuses after irradiation with 2450 MHz microwaves]. / Rozwój zarodków i plodów myszy poddanych dzialaniu promieniowania mikrofalowego 2450 MHz.

Microwave radiation has been reported to produce adverse effects in a variety of biological systems. We attempted to estimate the influence of repeated expositions to 2450 MHz microwaves at power densities of 10 or 40 mW/cm2 on murine (Swiss) embryos and fetuses development. Mated females were divided into groups and irradiated in various periods of pregnancy. Control animals were placed in the anechoic chamber for similar periods of time. In the 4th day of gestation part of animals were killed, number, phase of development and morphology of embryos after their washing out from uterus were noted. Among embryos obtained from dames irradiated at 40 mW/cm2 (whole body MW hyperthermia) the lower percent of blastulas was counted while more embryos were in the phase of 2-8 blastomers . This suggests retardation of development in the early period of gestation in mice exposed to thermal MW fields. The other part of animals from experimental and control groups were killed on the 19th day of gestation. The fetuses and placentas were removed, weighed, the morphology of fetuses was evaluated. In mice exposed to microwaves at 40 mW/cm2 during the second half of pregnancy increased number of resorptions, stillbirths and internal hemorrhages was noted. The living fetuses had lowered body mass compared to the offsprings of sham-irradiated mice.

[Survival and physical development of progeny of Swiss mice after 2450 Mhz microwave irradiation during pregnancy]. / Przezywalnosc i rozwój fizyczny potomstwa myszy poddanych w czasie ciazy dzialaniu mikrofal 2450 MHz.

The influence of prenatal repetitive 2450 MHz microwave irradiation of Swiss mice on postnatal survival and development was investigated. The animals were divided after mating into experimental and control groups and irradiated at power densities of 10 or 40 mW/cm2 at various periods of gestation. The pregnant females were allowed to deliver at term and feed their offsprings. Size of the litters and body mass of springs were checked on the 4th, 12th day of life. In progeny delivered by females irradiated at 40 mW/cm2 during the second half of pregnancy lowered increments of body mass before the 12th day of life was noted. We observed as well the lower size of litters delivered by females irradiated in the same conditions during the first half of pregnancy.