Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0153470 (Spleen)
 4,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Merocyanine 540 (MC540)-mediated photodynamic action is a novel approach for purging tumor cells from autologous remission bone marrow explants. The purpose of this study was to evaluate the effects of hemin (ferriprotoporphyrin IX), a potential source of pro-oxidant iron in bone marrow, on in vitro photodynamic inactivation of leukemia cells. Murine L1210 cells exhibited a progressive loss of clonogenicity when irradiated with broad-band visible light in the presence of MC540. Hemin had strikingly different effects on photokilling, depending on its contact time with cells, eliciting a sizable decrease in resistance after short-term (30-min) contact but a marked increase in resistance after long-term (24-h) contact. Similar trends were observed when cells were challenged with glucose/glucose oxidase, indicating that the responses apply to more than one type of oxidative stress. Immunoblot analyses revealed that the levels of inducible heme oxygenase (HO-1) and ferritin heavy (H) chain were substantially elevated 24 h after hemin addition. HO-1 increased relatively rapidly and maximized within 4 h after adding hemin, whereas H-ferritin increased more slowly in parallel with the development of hyperresistance, maximizing after 24-36 h. Desferrioxamine, an avid iron chelator, had no effect on HO-1 induction but inhibited both ferritin induction and the increase in cell resistance, suggesting that HO-mediated release of iron from hemin was necessary for triggering these responses. Spleen apoferritin was taken up by L1210 cells and strongly inhibited photokilling, further implicating ferritin involvement in hyperresistance. Photokilling was accompanied by free radical-mediated lipid peroxidation (thiobarbituric acid reactivity), which could be suppressed substantially by 24-h hemin preincubation. A plausible explanation for the long-term effects of hemin is that excess H-ferritin generated as a result of iron-regulatory protein deactivation sequesters toxic iron, which might otherwise catalyze damaging lipid peroxidation. Chronic oxidative release of hemin from bone marrow erythroid cells could compromise the efficacy of photopurging by making tumor cells more tolerant to photooxidative insult.
 ...
PMID:Hyperresistance of leukemia cells to photodynamic inactivation after long-term exposure to hemin. 884 Sep 77

Aniline-induced splenic toxicity is characterized by hemorrhage, capsular hyperplasia, fibrosis, and a variety of sarcomas in rats. Early biochemical events responsible for the observed effects are not known. To understand the mechanism(s) of aniline-induced splenic toxicity, single and multiple (four and seven) doses of 1 mmol/kg of aniline hydrochloride(AH) were given in rats. Apart from changes in the hematological parameters, these studies demonstrated that AH could induce lipid peroxidation and protein oxidation in the spleen, and significant increases were observed at four doses. Subsequently, a dose-response study of AH was performed. Male SD rats were given four doses each (one dose/day) of 0.25, 0.5, 1, and 2 mmol/kg of AH in water by gavage, while controls received water only. Animals were euthanized 24 hr following the last dose and tissues obtained. Spleen weight increased by 32 and 80% at 1 and 2 mmol/kg doses, respectively. Splenic lipid peroxidation showed dose-dependent increases of 24, 32, and 43% at 0.5, 1, and 2 mmol/kg, respectively. Protein oxidation in the spleen, quantitated by carbonyl content per milligram protein, showed 10, 28, and 27% increases at 0.5, 1, and 2 mmol/kg, respectively. Iron content in the spleen also showed dose-dependent increases of 72, 172, and 325% at 0.5, 1, and 2 mmol/kg, respectively. Dose-related histopathologic expansion of splenic red pulp was characterized by increasing vascular congestion (most pronounced at 2 mmol/kg), increased red pulp cellularity, erythrophagocytosis, and cellular fragmentation at 1 and 2 mmol/kg; iron deposition in red pulp also increased dramatically with dose. These studies establish that aniline induces lipid peroxidation and protein oxidation in the spleen and suggest that oxidative stress plays a role in the splenic toxicity of aniline.
 ...
PMID:Oxidative stress in the splenotoxicity of aniline. 902 70

The Belgrade laboratory (b/b) rat is a mutant animal suffering of a severe anemia, resulting from a severe intracellular iron deficiency. This deficiency is determined by an impaired intracellular transport of iron due to a block located between the endocytic vesicles and the cytosolic iron transport to mitochondria. This results in a complex series of disturbances affecting hemopoietic stem and progenitor cells, as well as growth factor production. The gene affected by the "b" mutation is unknown. This review summarizes the current knowledge on b/b rat hemopoiesis, with the focus on pluripotent hemopoietic progenitors, such as Spleen Colony Forming Units scored at day 8 after transplantation (CFU-Sd8) and more primitive stem cells (pre-CFU-S) responsible for Marrow Repopulating Ability. A special effort was made to describe the effects of b/b mutation on hemopoietic stem cells distinguishing between the alterations connected to the primary defect (intracellular iron deficiency), and those secondary to severe anemia (severe chronic hypoxia). The intracellular iron deficiency is responsible for a reversible cytostatic effect on CFU-Sd8, while the overcoming of this proliferative block reveals that the size of bone marrow CFU-Sd8 population is limited by the level of oxygenation. The size of pre-CFU-S population is also limited by the level of oxygenation, implying that, in contrast to the normal situation, in b/b rats pre-CFU-S are actively proliferating and therefore sensitive to hypoxia. This review also explains how to get more reliable data on the effects of intracellular iron deficiency and hypoxia on the proliferation of hemopoietic stem and progenitor cells and points to the potential importance of b/b rat phenomenon for fundamental research in cell biology and in the search of new ways to restrain the proliferation of malignant cells.
 ...
PMID:Hemopoietic stem cell proliferation in Belgrade rats: to complete the parable. 949 90

Splenomegaly was observed both in male and female Sprague-Dawley rats after 1 week of exposure to CdCl2 (0.6 mg Cd/kg/day). Spleen weight reached about double that in controls by 8 weeks of Cd exposure. Histopathological examination of the enlarged spleen revealed that iron- and lipid-laden histiocytes were clustered in the periarterial lymphatic sheath, and the red pulp appeared to be expanded. It is noteworthy that electron microscopy revealed marked poikilocytosis and Heinz body formation in red blood cells (RBCs) in both the sinus and cord. Histiocytes were swollen by a granular substance in the cytoplasm and also many secondary lysosomes. These morphological findings indicate that degradation of damaged RBCs induced by exposure to Cd might be promoted in the spleen and possibly cause splenomegaly. This RBC damage-hemolysis-splenomegaly sequence is also considered to be associated with the etiology of Cd-induced anemia. In addition to the abnormal RBC degradation, nuclei of lymphocytes in the Cd-exposed spleen exhibited high electron density, consistent with a preapoptotic state suggesting the immunosuppressive effect of Cd.
 ...
PMID:Pathological study of splenomegaly associated with cadmium-induced anemia in rats. 955 25

We investigated the effect of dietary magnesium (Mg) deficiency on the nutritive utilization and tissue distribution of iron (Fe). Wistar rats were fed an Mg-deficient diet (56 mg/kg) for 70 days. Absorbed Fe, Fe balance, number of the erythrocytes [red blood cells (RBC)] and leukocytes white blood cells (WBC)], hemoglobin (Hb), and Fe content were determined in samples of plasma, whole blood, skeletal muscle, heart, kidney, liver, spleen, femoral bone, and sternum obtained on experimental days 21, 35, and 70. The Mg-deficient diet significantly increased Fe absorption and Fe balance from week 5 until the end of the experimental period. This effect was accompanied by a significant decrease in the concentration of RBC and Hb from day 35, which caused the decrease in whole blood Fe seen on day 70. However, WBC were significantly increased from day 21 until the end of the experimental period. Mg deficiency significantly increased plasma and liver Fe at all three time points investigated. Spleen, heart, and kidney Fe were significantly increased only at the end of the study. However, on day 70, Fe concentration in the sternum had decreased significantly. No changes were found in skeletal muscle or femur Fe content. Mg deficiency led to increased intestinal absorption of Fe and decreased RBC counts, possibly as a result of increased fragility of the erythrocytes. Intestinal interactions between Fe and Mg, together with activation of erythropoiesis as a result of hemolysis, favored intestinal absorption of Fe. This situation gave rise to an increase in plasma Fe levels, which in turn favored Fe uptake and storage by different organs, especially the liver and spleen. However, despite the increased Fe content seen in the tissues of rats fed the Mg-deficient diet, these animals were unable to compensate for the hemolysis caused by this nutritional deficiency.
 ...
PMID:Influence of magnesium deficiency on the bioavailability and tissue distribution of iron in the rat. 1071 95

To elucidate the mechanism(s) of splenic toxicity of aniline, studies were conducted with nitrosobenzene (NB), an N-oxidized metabolite of aniline. Male Sprague-Dawley rats were given 0.025, 0.05, 0.1, or 0.2 mmol/kg/d of NB in 0.5 ml of 0.25% agar by gavage for 4 d; control rats received the vehicle only. Animals were euthanized at 24 h following the last dose. NB treatment resulted in decreased erythrocyte counts, whereas methemoglobin content increased at 0.1- and 0.2-mmol/kg doses. Spleen weight to body weight ratios were greater by 55 and 81% at O.1- and 0.2-mmol/kg NB doses, respectively. Total iron content in the spleens of NB-treated rats showed dose-dependent significant increases, and the nonheme iron followed a similar pattern. Splenic lipid peroxidation showed a dose-dependent response and was greater by 19, 56, 74, and 85% at the 4 doses, respectively. Malondialdehyde (MDA)-protein adducts, as quantitated by a competitive enzyme-linked immunosorbent assay (ELISA), were markedly greater in all the NB-treated groups, with the highest increase of 248% at 0.2 mmol/kg. Furthermore, NB exposure also resulted in greater protein oxidation (carbonyl content) in the spleens at 0.1- and 0.2-mmol/kg doses. These results suggest that NB is a splenotoxin and therefore can contribute to the splenic toxicity of aniline. Results of this study further support our earlier findings that oxidative stress is a potential mechanism in the splenotoxicity of aniline.
 ...
PMID:Contribution of nitrosobenzene to splenic toxicity of aniline. 1091 91

The Brown Norway (BN) rat is reported to be resistant to the induction of experimental autoimmune encephalomyelitis (EAE) and a number of mechanisms have been suggested to explain this resistance. In work reported here we provide evidence that such resistance in the BN rat can be accounted for, at least in part, by their ability to produce higher levels of nitric oxide (NO) than susceptible strains of rats. Spleen cells from the BN rat make significantly more NO following in vitro stimulation than do cells from the Lewis or PVG rat and following in vivo immunization using complete Freund's adjuvant (CFA) the BN rat makes substantially more NO than either susceptible strain. If carbonyl iron is used as adjuvant in vivo there is no increase in NO levels in the BN rat and they are rendered highly susceptible to EAE. Immunizing with CFA simultaneously with neuroantigen and carbonyl iron drives up NO levels and the resistance is restored. EAE produced using carbonyl iron is characterized by extensive macrophage/microglia presence in the central nervous system lesions of the BN rat yet the cytokine profile in the lymph nodes does not differ from that in the EAE Lewis rats.
 ...
PMID:Nitric oxide contributes to resistance of the Brown Norway rat to experimental autoimmune encephalomyelitis. 1563 8

Health risks due to exposure to high-linear energy transfer (LET) charged particles remain unclear. The major goal of this study was to confirm and further characterize the acute effects of high-LET radiation ((56)Fe(26)) on erythrocyte, thrombocyte and leukocyte populations in three body compartments after total-body exposure. Adult female C57BL/6 mice were irradiated with total doses of 0, 0.5, 2 and 3 Gy and killed humanely 4 days later. Body and organ masses were determined and blood, spleen and bone marrow leukocytes were evaluated using a hematology analyzer and flow cytometry. Spleen and thymus (but not body, liver and lung) masses were significantly decreased in a dose-dependent manner. In general, red blood cell (RBC) counts and most other RBC parameters were depressed with increasing dose (P < 0.05); the major exception was an increase in cell size at 0.5 Gy. Platelet numbers and volume, total white blood cell counts, and all three major types of leukocytes also decreased (P < 0.05). Lymphocyte populations in blood and spleen exhibited variable degrees of susceptibility to (56)Fe-particle radiation (B > T > NK and T cytotoxic > T helper cells). In the bone marrow, leukocytes with granulocytic, lymphocytic ("dim" and "bright"), and monocytic characteristics exhibited proportional variations at the higher radiation doses in the expression of CD34 and/or Ly-6A/E. The data are discussed in relation to our previous investigations with iron ions, other forms of radiation, and space flight in this same animal model.
 ...
PMID:Acute effects of iron-particle radiation on immunity. Part I: Population distributions. 1639 64

This study was designed to track systemically administered mononuclear cells (MNCs) in the ischemic mouse brain using 7 T magnetic resonance imaging (MRI). Splenectomized wild-type mice were subjected to brain ischemia by 30 or 60 min filamentous occlusion of the middle cerebral artery (MCAo) and reperfusion. Spleen-derived MNCs were labeled with very small superparamagnetic iron-oxide particles (VSOP) and transfused into recipient mice 30 min, 8 h, or 24 h after MCAo via the tail vein. High-resolution MRI sequences were designed to monitor the dynamics of brain ischemia and to observe the migration and engraftment of transfused cells into the ischemic brain. T2*-weighted (gradient-echo) hypointense signal changes became apparent at 24-48 h after transfusion, were typically associated with the ischemic lesion border, and could be followed up to 5 weeks after the insult. Such presumed MNC-associated signal changes in MRI were confirmed by histochemical detection of iron (Prussian blue staining) and detection of constitutively expressed green fluorescent protein (GFP) in a subset of animals transfused with MNCs derived from GFP transgenic mice. Taken together, our results demonstrate that brain engraftment of systemically administered mononuclear cells can be visualized non-invasively over time and space using high-resolution MRI.
 ...
PMID:Tracking of systemically administered mononuclear cells in the ischemic brain by high-field magnetic resonance imaging. 1697 81

Kidney disease is a frequent consequence of heavy metal exposure and renal anemia occurs secondarily to the progression of kidney deterioration into chronic disease. In contrast, little is known about effects on kidney of chronic exposure to low levels of depleted uranium (DU). Study was performed with rats exposed to DU at 40 mg/l by chronic ingestion during 9 months. In the present work, a approximately 20% reduction in red blood cell (RBC) count was observed after DU exposure. Hence, three hypotheses were tested to determinate origin of RBC loss: (1) reduced erythropoiesis, (2) increased RBC degradation, and/or (3) kidney dysfunction. Erythropoiesis was not reduced after exposure to DU as revealed by erythroid progenitors, blood Flt3 ligand and erythropoietin (EPO) blood and kidney levels. Concerning messenger RNA (mRNA) and protein levels of spleen iron recycling markers from RBC degradation (DMT1 [divalent metal transporter 1], iron regulated protein 1, HO1, HO2 [heme oxygenase 1 and 2], cluster of differentiation 36), increase in HO2 and DMT1 mRNA level was induced after chronic exposure to DU. Kidneys of DU-contaminated rats had more frequently high grade tubulo-interstitial and glomerular lesions, accumulated iron more frequently and presented more apoptotic cells. In addition, chronic exposure to DU induced increased gene expression of ceruloplasmin (x12), of DMT1 (x2.5), and decreased mRNA levels of erythropoietin receptor (x0.2). Increased mRNA level of DMT1 was associated to decreased protein level (x0.25). To conclude, a chronic ingestion of DU leads mainly to kidney deterioration that is probably responsible for RBC count decrease in rats. Spleen erythropoiesis and molecules involved in erythrocyte degradation were also modified by chronic DU exposure.
 ...
PMID:Renal anemia induced by chronic ingestion of depleted uranium in rats. 1837 46


<< Previous 1 2 3 4 5 6 7 8 Next >>