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R Kozlowski

Publications and source records attributed to R Kozlowski.

15 recordsLinked to original sources
PubMed2001

In utero haemopoietic sensitivity to alpha, beta or X-irradiation in CBA/H mice.

PURPOSE: To assess in utero sensitivity to x-rays, alpha-emissions from plutonium-239 and beta-emissions from tritium in terms of induction of chromosomal aberrations in bone marrow cells. MATERIALS AND METHODS: CBA/H mice were exposed to a single dose of X-rays (0.5Gy) on either day 7 or day 14 of pregnancy or given (239)Pu (100 kBq kg(-1)) by intraperitoneal injection on either day 6 or day 13. Tritium was administered to mice throughout pregnancy as either tritiated water, ad libitum in drinking water (total intake averaged 130 MBq), or as homogenized tritiated cress, administered by gastric intubation (total 60 MBq). Irradiated and unexposed control mice and their offspring were sacrificed at 2-8 weeks after birth. Direct metaphase preparations from femoral bone marrow cells from mothers and offspring were used for G-band analysis. RESULTS: The incidence of stable aberrations was significantly and similarly increased in neonatal and maternal marrow samples after exposure to X-rays, (239)Pu or (3)H. The estimated average bone absorbed doses from (239)Pu in pregnant females were similar to the X-ray dose of 0.5 Gy, suggesting a low RBE for alpha-irradiation in adults. The similar levels of damage observed in neonates after X-irradiation and 239Pu exposure are indicative of greater in utero sensitivity to alpha-irradiation since the overall estimated in utero alpha-particle doses to haemopoietic tissue were much lower. In utero doses from (3)H and corresponding maternal doses were around 0.5Gy, showing no evidence of greater in utero sensitivity, no significant difference between the effects of the two forms of tritium, and were consistent with an RBE value of 1-2. CONCLUSIONS: Comparison of stable aberration yields in haemopoietic cells suggests a greater sensitivity to alpha-particles from (239)Pu than X-rays or beta-particles from (3)H for irradiation in utero but a low RBE value in adults.

Age Factors↗
PubMed2001

Chronic ischemia alters prostate structure and reactivity in rabbits.

PURPOSE: Autopsy studies performed in men older than 80 years old have demonstrated that 90% have histological evidence of benign prostatic hyperplasia. Despite this fact pressure flow studies in men of this age who are referred for the evaluation of lower urinary tract symptoms have shown that only 40% have evidence of bladder outlet obstruction. To our knowledge the specific features of benign prostatic hyperplasia responsible for bladder outlet obstruction are not known. To investigate the possible etiological factors responsible for bladder outlet obstruction we determined whether chronic ischemia alters the structural and functional properties of the prostate. MATERIALS AND METHODS: Male New Zealand White rabbits weighing 3.5 to 4 kg. were divided into a chronic prostate ischemia (12), hypercholesterolemia (8) and age matched control (8) group. The chronic prostate ischemia group underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet, the hypercholesterolemia group received a 0.5% cholesterol diet only and controls received a regular diet. After 12 weeks using anesthesia iliac artery and prostatic blood flow was measured by an ultrasonic and laser Doppler flowmeter, respectively. The animals were then sacrificed and the prostate was processed for histological evaluation, immunohistochemical staining for vascular endothelial growth factor expression and organ bath studies. RESULTS: Iliac artery and prostatic blood flow was significantly decreased in the chronic prostate ischemia compared with the hypercholesterolemia and control groups. Histological findings included thickening and fibrosis of the prostatic stroma and cystic atrophy of the epithelium in the chronic prostate ischemia group as well as minor thickening of the stroma in the hypercholesterolemia group. These structural changes correlated with decreased vascular endothelial growth factor expression. Organ bath studies showed that chronic ischemia and to a lesser extent hypercholesterolemia impaired electrical field stimulation induced neurogenic relaxation of the prostatic tissue. Neurogenic relaxation of the prostatic tissue was improved by combined treatment with indomethacin and L-arginine in the hypercholesterolemia but not in the chronic prostate ischemia group. Nitric oxide donor sodium nitroprusside produced comparable relaxation in all 3 groups. CONCLUSIONS: Chronic ischemia causes marked changes in prostatic structure and contractility. Ischemia induced glandular atrophy was consistently associated with decreased vascular endothelial growth factor expression. Decreased relaxation of the ischemic tissue to electrical field stimulation appears to involve the nitric oxide pathway. The nitric oxide precursor L-arginine reversed hypercholesterolemia induced impairment of prostatic tissue relaxation. Our study suggests that chronic ischemia results in thickening and fibrosis of the prostate, changing its mechanical properties. Chronic ischemia also impairs neurogenic relaxation in the prostate. We discuss the possible relationship of these changes to clinical bladder outlet obstruction.

Animals↗
PubMed1999

Overactivity and structural changes in the chronically ischemic bladder.

PURPOSE: Our aim was to study the effect of chronic ischemia on bladder contraction and detrusor smooth muscle reactivity. The relationship between structural damage and functional changes in the chronically ischemic bladder was also investigated. MATERIAL AND METHODS: Male New Zealand White rabbits were divided into arterial injury (AI), hypercholesterolemia (Hch) and control groups. The AI group (n = 18) underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet. The Hch group (n = 8) received a 0.5% cholesterol diet alone. The control group (n = 8) received a regular diet. After 16 weeks, iliac artery and bladder wall blood flows were recorded. Cystometrograms and arteriography were obtained and bladder tissues were processed for isometric tension measurement in the organ bath and for histological evaluation. RESULTS: At 16 weeks, blood flow through the iliac arteries was significantly reduced in the AI group compared with the Hch and control groups. In the AI group, 8 animals developed severe bladder ischemia (SBI) defined as greater than 60% decrease in bladder blood flow, 7 animals developed moderate bladder ischemia (MBI) defined as 40 to 60% decrease in bladder blood flow, and 3 animals failed to develop significant bladder ischemia (<40% decrease in bladder blood flow). In the control animals, bladder blood flow increased prior to contraction, decreased during contraction and rebounded to baseline levels after contraction. In animals with MBI and SBI, the increase in bladder blood flow prior to contraction and the rebound of blood flow after contraction, both seen in control animals, were diminished. Detrusor overactivity (significant increase in the frequency of spontaneous bladder contractions) was observed in the MBI group and impaired bladder contraction in the SBI group. In the organ bath, bladder strips from the MBI group demonstrated increased contractile response to carbachol and electrical field stimulation (EFS) while bladder strips from the SBI group showed impaired contractility. Hch alone produced only short-lived ischemia during bladder contraction and caused significantly lesser functional changes compared with those seen in MBI. Histological examination showed atherosclerotic occlusion in the iliac arteries and bladder microcirculation and marked disruption of urothelium in the MBI and SBI groups. Severe fibrosis was seen in bladder tissue from the SBI group, moderate fibrosis in tissue from the MBI group and mild fibrosis in tissue from the Hch group. CONCLUSIONS: Our studies show that chronic MBI is associated with detrusor overactivity and increased smooth muscle contractility to carbachol and EFS while chronic SBI is associated with impaired detrusor contraction. The mechanism of chronic ischemia-induced bladder dysfunction is not known and may involve multiple physiologic and structural changes in the bladder nerves, receptors and contractile components. Our studies suggest that ischemia-induced structural damage in the urothelium and possible chronic exposure of the underlying tissue and nerves to the urine may also play a role in MBI-induced detrusor overactivity. SBI-induced impairment of bladder contraction may involve, in part, extensive fibrosis and loss of bladder smooth muscle. Histopathophysiologic changes in bladder tissue from our MBI model are similar to those seen in patients with detrusor instability, suggesting that chronic ischemia may play a role in the development of idiopathic detrusor instability.

Animals↗
PubMed1998

The importance of ion channels for macrophage and microglial activation in vitro.

Microglia, the resident macrophages of the central nervous system (CNS), are activated rapidly in response to neuronal injury. In the search for factors which regulate inflammation resulting from pathology in the CNS, it is logical to focus on changes in the local environment which occur following neuronal death. These include transient alterations in transmembrane ion gradients. Electrophysiological studies have provided information on the range of ion channels expressed by macrophages and microglia in vitro. The purpose of this study was to focus on the biology of macrophages and the role ion channels play in determining their activity. We show that potassium channels are unlikely to be involved in the generation of nitric oxide by activated macrophages and microglial cell lines in vitro. Chloride channels are more likely to contribute to this response. Our results question the functional importance of the observed differences between the potassium channel expression in vitro of macrophages and microglia.

Animals↗
PubMed1994

Evidence for internal autocrine regulation of growth in acute myeloblastic leukemia cells.

Blast cells from 70% of patients with acute myeloid leukemia (AML) show some evidence of in vitro autonomous growth, which appears to be related to the autocrine secretion of growth factors, particularly granulocyte-macrophage colony-stimulating factor (GM-CSF). In the majority of cases, the growth factors appear to be involved in classical extracellular autocrine or paracrine loops with neutralizing antibodies to the relevant cytokine inhibiting growth. In a minority, however, antibodies do not inhibit growth despite evidence of secretion of the cytokine. There is evidence for intracellular autocrine loops in murine leukemic cell lines. In this study, we wished to investigate for the presence of such intracellular loops involving GM-CSF in AML blast cells. Blast cells from 11 patients with AML were cultured in the presence of either neutralizing GM-CSF antibody or an antisense oligonucleotide directed against GM-CSF. We also studied the effect of the oligonucleotide on the autonomous growth of cells whose production of GM-CSF had been apparently abolished by either interleukin-1 receptor antagonist (IL-1Ra) or following blast cell purification using the CD34 antigen. The autonomous growth of the blast cells from nine of the 11 patients was inhibited by the antisense oligonucleotide (but not by the control sense oligonucleotide). However, only six of the nine were inhibited by the anti-GM-CSF antibody. Similarly, in one patient whose CD34 purified blast cells continued to show a high degree of autonomous growth but did not produce detectable GM-CSF, growth was inhibited by the antisense oligonucleotide but not by antibody, while in another patient whose cells were inhibited by IL-1Ra with, again, loss of detectable GM-CSF, growth could be further inhibited by the addition of the oligonucleotide but not the antibody. These studies provide evidence that intracellular autocrine loops involving GM-CSF are involved in the autonomous growth of some AML blast cells.

Antibodies↗
PubMed1993

The use of ATP bioluminescence as a measure of cell proliferation and cytotoxicity.

Adenosine triphosphate (ATP) bioluminescence was used to determine whether there was a linear relationship between cultured cell number and measured luminescence using the luciferin-luciferase reaction. In all the cells tested including peripheral blood mononuclear cells (MNC), MOLT-4, HL-60, TF-1, NFS-60 and L-929 cell lines there was a significant correlation as determined by Spearman's rank correlation coefficient (p > 0.00001). These observations were then used to determine whether ATP bioluminescence could be used as a suitable substitute for tritiated thymidine uptake as a measure of cell proliferation. The cell lines MOLT-4, HL-60, TF-1 and NFS-60 showed a strong correlation between thymidine uptake and ATP bioluminescence (p > 0.00001 for all cell types). Additionally the ATP method could detect the cytokine dependent proliferation on TF-1 and NFS-60 cells by granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) respectively. The tumour necrosis factor alpha (TNF)-induced cytotoxic effect on L-929 cells could also be accurately detected using this method. It would therefore appear to be possible to use ATP bioluminescence in the detection of cytokine activity in a number of different bioassays.

Adenosine Triphosphate↗
PubMed1992

Role of autocrine and paracrine production of granulocyte-macrophage colony-stimulating factor and interleukin-1 beta in the autonomous growth of acute myeloblastic leukaemia cells--studies using purified CD34-positive cells.

The blast cells from some patients with acute myeloblastic leukemia (AML) proliferate autonomously in vitro. We have previously identified four groups of AML blasts based upon their growth characteristics in vitro, in particular the degree of autonomous growth. We have now measured the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-1 beta (IL-1 beta) by AML cells with different growth characteristics, using two sensitive enzyme-linked immunosorbent assays. Our results show a correlation between the capacity of AML blasts to produce GM-CSF and IL-1 beta and the ability to grow autonomously in vitro. Blasts from cells with no autonomous growth (n = 5) secreted low or undetectable amounts of GM-CSF and IL-1 beta. Blasts with totally autonomous growth (n = 10) secreted the highest levels of GM-CSF (mean 2469 pg/10(3) cells) and IL-1 beta (mean 3156 pg/10(6) cells). Whereas blasts with partially autonomous growth (n = 9) secreted intermediate levels of GM-CSF (mean 270 pg/10(6) cells) and IL-1 beta (mean 931 pg/10(6) cells). In order to determine whether GM-CSF production was autocrine or the consequence of paracrine secretion by differentiated leukemic cells, we studied the degree of autonomous growth and production of GM-CSF by CD34-positive blasts from eight patients whose unfractionated cells produced GM-CSF. We found that CD34-positive blasts from six of these cases grew autonomously to a degree comparable to that of the unfractionated cells, and that CD34-positive blasts produced GM-CSF either autonomously or in response to recombinant IL-1 beta. Our data suggests that in the majority of cases, CD34-positive blasts are capable of autonomous growth and autocrine GM-CSF production, however this is variably regulated by the paracrine production of IL-1 beta by CD34-negative cells.

Antigens, CD↗
PubMed1990

Interleukin-1 is one factor which regulates autocrine production of GM-CSF by the blast cells of acute myeloblastic leukaemia.

The role of interleukin-1 (IL-1) as a regulator of the autonomous growth of the blast cells of acute myeloid leukaemia (AML) has been studied on samples isolated from 15 patients. In nine out of 10 patients with evidence of partial autonomous blast cell growth. IL-1 further stimulated cell growth in both suspension culture and in a clongenic assay. IL-1 also stimulated cell growth in two out of three cases with no evidence of autonomous growth whereas no additional stimulation was observed in two cases with totally autonomous growth. In blast cells stimulated by IL-1, synthesis of granulocyte-macrophage colony stimulating factor (GM-CSF) was increased and the proliferative response to IL-1 was inhibited by an antibody to GM-CSF. In all samples with evidence of autonomous growth, blast cell conditioned medium (BCCM) contained IL-1 activity (range 0.7-74.2 units ml) and a polyclonal antibody to IL-1 markedly inhibited autonomous growth in four samples. BCCM from three of these four samples contained GM-CSF, the synthesis of which was suppressed when BCCM was prepared in the presence of anti-IL-1. Our data suggests that endogenous IL-1 is an important factor in the regulation of the production of GM-CSF and hence of autonomous growth of AML blasts, but that other mechanisms regulating GM-CSF production may exist.

Cell Division↗
PubMed1990

Endogenous interleukin-1 can regulate the autonomous growth of the blast cells of acute myeloblastic leukemia by inducing autocrine secretion of GM-CSF.

We have studied peripheral blood blast cells from a patient with acute myeloblastic leukemia (AML) whose cells proliferated autonomously at high cell density, but only in the presence of adherent cells. At low cell density in suspension culture and in a clonogenic assay, blast cell growth was stimulated by recombinant granulocyte macrophage colony stimulating factor (GM-CSF) and recombinant interleukin-1 (IL-1) independently. The response to rIL-1 was inhibited (less than 90%) by anti-GM-CSF, suggesting that the proliferative response to IL-1 was mediated by GM-CSF. This was supported by experiments which demonstrated that blast cell conditioned medium prepared in the presence of IL-1 contained GM-CSF activity which stimulated the growth of normal granulocyte-macrophage precursors (CFU-GM) and of homologous GM-CSF responsive AML blasts. As IL-1 but no GM-CSF activity was detected in BCCM prepared without exogenous IL-1 and a neutralizing antibody to IL-1 inhibited the autonomous growth of blasts in suspension culture, we conclude that the endogenous secretion of IL-1 by leukemic cells stimulated autocrine GM-CSF secretion, inducing autonomous growth of the blast cell population.

Cell Division↗
PubMed1989

Heterogeneous mechanisms of autocrine growth of AML blasts.

The ability of blast cells to grow autonomously and to produce autostimulatory growth factors has been investigated in 25 consecutive patients with AML. An autostimulatory index (ASI) was calculated (no. of colonies without CSF divided by no. of colonies with CSF) and patients classified into four groups: Group 1 (n = 3): non-growers; Group 2 (n = 4): CSF-dependent (ASI less than 0.1); Group 3 (n = 11): partially autonomous (ASI 0.1-0.8); and Group 4 (n = 7): fully autonomous/CSF-unresponsive (ASI greater than 0.8). In Group 3 patients colony formation and DNA synthesis were significantly (P less than 0.01) augmented by CSFs but at high cell concentrations became CSF-independent. Blast cell-conditioned medium (BCCM) from these patients exhibited potent autostimulatory activity, increasing DNA synthesis by less than or equal to 5-fold, and also stimulated CSF-dependent homologous blasts by less than or equal to 20-fold. In 5/5 this activity was neutralized by anti-GM-CSF, which also inhibited autonomous proliferation of their blast cells. Group 4 blasts also secreted GM-CSF but their BCCM possessed no autostimulatory activity, and anti GM-CSF failed to inhibit their autonomous growth. No membrane-associated CSF activity was found, however purified cytosolic fractions stimulated proliferation of CSF-dependent homologous blasts, consistent with production and secretion of CSF which is present in active form in the cytosol but does not autostimulate via membrane receptors. These results suggest that autocrine mechanisms are important in regulating blast cell proliferation, but that the mechanisms are heterogeneous.

Bone Marrow↗
PubMed1989

The role of cell contact and autostimulatory soluble factors in the proliferation of blast cells in acute myeloblastic leukemia.

The role of cellular interactions in stimulating leukemic cell proliferation was studied in AML. When peripheral blood blasts were cultured in suspension in flat-bottomed vessels at low cell numbers (15.6-500 x 10(3)/ml), the rate of DNA synthesis [( 3H]thymidine incorporation) was proportional to cell density. When cells were cultured under otherwise identical conditions in round-bottomed vessels, to induce cell crowding, the rate of DNA synthesis was independent of cell numbers and was significantly augmented (p less than or equal to 0.01). Physical separation of cells in round-bottomed (crowded) cultures by latex beads reduced DNA synthesis to the same rate as that in flat-bottomed (non-crowded) cultures. In contrast, addition of mitomycin-treated autologous blasts had little effect in crowded cultures but increased DNA synthesis in non-crowded cultures. DNA synthesis was also enhanced: by reducing culture volume to concentrate any diffusible factors produced by the cells or by blast cell conditioned medium from autologous blasts grown under crowded conditions. Cells cultured in suspension for 72 hr under crowded/non-crowded conditions both formed blast cell colonies in methyl cellulose; however, the number of colonies derived from crowded cultures was greater. These results indicate that cell proximity promotes proliferation of blasts and blast cell progenitors; both close cell contact and autostimulatory soluble factors are important in regulating growth of AML blasts.

Cell Adhesion↗
PubMed1988

Transferrin receptor expression of AML blasts is related to their proliferative potential.

Expression of the transferrin receptor (TfR) was studied on peripheral blood blast cells from 11 patients with acute myeloid leukaemia (AML). Using a monoclonal anti-TfR antibody (OKT9) and a polyclonal antibody against surface membrane-bound transferrin, a proportion of blasts from all the patients was found to express receptors for transferrin. Further analysis of OKT9 expression using a fluorescent activated cell sorter (FACS) showed that the TfR was heterogeneously distributed in the blast cell population. In five out of six samples studied, stimulation of DNA synthesis following short-term culture induced a several-fold increase in TfR display as analysed by flow cytometry using OKT9 or FITC-conjugated transferrin. Blasts from seven patients stained with OKT9 were separated on the FACS into positive and negative or weakly positive fractions. Culture of the TfR negative population in a blast cell colony assay produced no colonies in either of two patients. In a further five patients the colony forming cells were predominantly associated with the TfR strongly positive fraction (52 +/- 25 colonies/10(4) cells) rather than the TfR weakly positive fraction (12 +/- 11 colonies/10(4) cells). Analysis of colony size showed that clones derived from the weakly positive fraction were smaller than clones from the TfR strongly positive fraction. These results suggest that TfR display by AML blasts is related to their proliferative capacity and is expressed by the leukaemic stem cell fraction.

Antibodies, Monoclonal↗
PubMed1986

o-Isothiocyanate dihydropyridine (oNCS-DHP), a long-acting, reversible inhibitor of the Ca++ channel.

The binding characteristics and pharmacological properties of o-isothiocyanate dihydropyridine [oNCS-DHP; 2,6-dimethyl-3,5-dicarbomethoxy-4-(2-isothiocyanatophenyl)-1, 4-dihydropyridine] were investigated in guinea pig heart and ileum. [3H]oNCS-DHP bound to a single population of high-affinity sites (Bmax = 107 fmol/mg of protein and Kd = 0.99 nM) in cardiac membranes, with a specificity characteristic of dihydropyridine receptors. After incubation of membranes with the tracer (0.5 nM), addition of excess nifedipine (1 microM) caused a dissociation of [3H]oNCS-DHP from its binding site. The reversibility of [3H]oNCS-DHP binding was confirmed by the lack of affinity labeling of cardiac membranes as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis. oNCS-DHP inhibited the inward Ca++ current of isolated guinea pig cardiac myocytes as determined in voltage-clamp experiments. In isolated perfused guinea pig hearts, oNCS-DHP caused a concentration-dependent increase in coronary artery flow and a decrease in left ventricular pressure. The effects of the highest concentration (0.3 microM) were still near maximal after a 1-h washout. Suppression of K+ depolarization-induced contractures of isolated ileal longitudinal muscle strips by oNCS-DHP remained maximal even after 5 h of washout. In all of the three biological test systems investigated, the Ca++ channel activator Bay K 8644 caused a complete and rapid reversal of the inhibitory effects of oNCS-DHP. Thus, it can be concluded that oNCS-DHP does not bind irreversibly to Ca++ channel dihydropyridine receptors in guinea pig heart and ileum. However, the o-isothiocyanatophenyl substituent on the dihydropyridine molecule confers upon the compound a very long duration of Ca++ channel blocking activity.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗