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PubMed1987

5-Fluorouracil treatment after irradiation impairs recovery of bone marrow functions.

In mice, persisting radiation-induced growth retardation of hematopoietic tissue suggested that at least part of the surviving stem cells are genetically injured. Additional mitotic stress some time after the radiation insult might remove injured stem cells, thus improving the overall recovery of the irradiated bone marrow. Mice were treated with 5 Gy whole-body gamma irradiation. Two weeks later half of the animals were injected i.v. with 150 mg/kg 5-fluorouracil (5-FU), the other half remained untreated (5 Gy-controls). 2 or 10 weeks later, femoral cellularity and CFU-S content, proliferation ability of transplanted bone marrow and the compartment ratio (CR; ratio of splenic IUdR incorporation at day 3 and number of CFU-S transfused) were determined. Four weeks after 5 Gy and 2 weeks after 5-FU treatment all parameters showed significant impairment of recovery. 12 weeks after 5 Gy and 10 weeks after 5-FU CFU-S and CR were still reduced compared to the 5 Gy-controls. 5-FU treatment of unirradiated mice did not produce permanent effects on the quality of stem cells or the hematopoietic microenvironment. It is concluded, therefore, that an increased proliferation stimulus does not aid in the removal of injured CFU-S and may even impair recovery of bone marrow functions by increasing the proportion of genetically injured stem cells which continue proliferation.

Animals↗
PubMed2003

A bit of give and take: the relationship between the extracellular matrix and the developing chondrocyte.

The extracellular matrix (ECM), once thought to be a static structural component of tissues, is now known to play a complex and dynamic role in a variety of cellular functions in a number of diverse tissues. A significant body of literature attests to the ability of the ECM to communicate both spatial and temporal information to adherent cells, thereby directing cell behavior via interactions between the ECM and cell-surface receptors. Moreover, volumes of experimental data show that a great deal of communication travels in the opposite direction, from the cell to the ECM, allowing for regulation of the cues transmitted by the ECM. As such, the ECM, with respect to its components and their organization, is not a fixed reflection of the state the local microenvironment in which a cell finds itself at a particular time, but rather is able to respond to and effect changes in its local microenvironment. As an example of the developmental consequences of ECM interactions, this review gives an overview of the 'give and take' relationship between the ECM and the cells of the developing skeletal elements, in particular, the chondrocyte.

Animals↗
PubMed1999

New insights into the molecular pathophysiology of polycystic kidney disease.

Polycystic kidney diseases are characterized by the progressive expansion of multiple cystic lesions, which compromise the function of normal parenchyma. Throughout the course of these diseases, renal tubular function and structure are altered, changing the tubular microenvironment and ultimately causing the formation and progressive expansion of cystic lesions. Renal tubules are predisposed to cystogenesis when a germ line mutation is inherited in either the human PKD1 or PKD2 genes in autosomal dominant polycystic kidney disease (ADPKD) or when a homozygous mutation in Tg737 is inherited in the orpk mouse model of autosomal recessive polycystic kidney disease (ARPKD). Recent information strongly suggests that the protein products of these disease genes may form a macromolecular signaling structure, the polycystin complex, which regulates fundamental aspects of renal epithelial development and cell biology. Here, we re-examine the cellular pathophysiology of renal cyst formation and enlargement in the context of our current understanding of the molecular genetics of ADPKD and ARPKD.

Animals↗
PubMed2006

A mouse model system to genetically dissect the molecular mechanisms regulating tumorigenesis.

The vast majority of human tumors are of epithelial origin and result from the accumulation of mutations that alter the function of pathways that control critical cellular processes, including proliferation, checkpoint regulation, and apoptosis. Authentically replicating these events in animal models is critical to understanding the biology of cancer and for testing the feasibility of novel therapies. We developed a mouse model that recapitulates the steps of epithelial tumor progression of multiple tissue types (kidney, breast, ovarian surface, and prostate epithelia), which takes advantage of the power of mouse genetics, and that allows for biochemical analysis, genetic selection, and screening. Moreover, this model enables functional interrogation of far more complex tumor genotypes, both of the tumor cells themselves, and of the cells in the tumor microenvironment. This is a crucial advantage, as human tumors result from multiple compound mutations, most of which are difficult to achieve through standard mutant mouse technology. We have applied this model to establish the role of apoptosis in epithelial solid tumor progression and in treatment response, which has provided novel opportunities for cancer therapies in humans.

Animals↗
PubMed1994

Interleukin-8, interleukin-6, and soluble tumour necrosis factor receptor type I release from a human pulmonary epithelial cell line (A549) exposed to respiratory syncytial virus.

The release of interleukin-8 (IL-8), interleukin-6 (IL-6) and the soluble forms of the tumour necrosis factor receptor (sTNF-R) from human pulmonary type II-like epithelial cells (A549) after respiratory syncytial virus (RSV) infection was analysed. RSV infection alone induced a time- and RSV dose-dependent IL-8 and IL-6 release from A549 cells. Furthermore, the soluble form of the TNF-RI was also secreted in a time- and RSV dose-dependent fashion. The soluble TNF-RII was not detected in the cell supernatant of infected epithelial cells. The effect of various cytokines [IL-1 alpha/beta, TNF-alpha/beta, IL-3, IL-6, interferon-gamma (IFN-gamma), transforming growth factor-beta 2 (TGF-beta 2)] and colony-stimulating factors [granulocyte (G)-CSF; granulocyte-macrophage (GM)-CSF] on the IL-8 release from A549 cells was also studied. Our data show that the proinflammatory cytokines IL-1 alpha/beta and TNF-alpha/beta induced an IL-8 release in non-infected A549 cells, and increased the IL-8 release of RSV-infected A549 cells synergistically. In addition, IL-3, G-CSF, IFN-gamma and TGF-beta 2, albeit at high concentrations, induced a low IL-8 release from non-infected A549 cells. The enhanced IL-8 secretion rates were accompanied with elevated cytoplasmic IL-8 mRNA steady state levels, as was shown by Northern blot analysis. Cellular co-culture experiments performed with A549 cells and polymorphonuclear granulocytes or peripheral blood mononuclear cells revealed that increased IL-8 amounts were secreted in the co-culture of non-infected as well as RSV-infected cells. The present study suggests a central role for the airway epithelium during RSV infection with regard to cytokine and cytokine receptor release, resulting in a recruitment and activation of inflammatory and immune effector cells. Our data also suggest that paracrine cytokine networks and cell-cell contact are involved in the regulation of IL-8 secretion within the microenvironment of the bronchial epithelium.

Blotting, Northern↗
PubMed1993

The nephritogenic T lymphocyte response in interstitial nephritis.

The work that has gone on regarding the development of nephritogenic T cells, their interactions with somatic structures in the kidney, and the vast biology that is engaged by their appearance are all amenable to study using the modern techniques of cellular and molecular biology. The models that have been developed to date illustrate common themes. The genes that encode for the effects of nephritogenic T cells operate by using the same general parameters as would be predicted for immune responses traditionally activated within the lymphoid compartment. Their immune response genes probably encode for structural proteins, some of which have been described, like the T cell receptor, T cell differentiation markers, MHC determinants, and cell-cell adhesion molecules. Maturation of nephritogenic T cell repertoires is fine-tuned by peripheral regulatory events and the cytokine bath produced by that microenvironment. Finally, CD8+ T cells that are programmed to damage the kidney can deliver signals which provoke phenotypically distinct patterns of injury. The future of research in this area holds great promise for developing a variety of new therapeutic modalities that involve antigen-specific regulation of nephritogenic T cell responses, control of cell-specific chemoattractants, modulation of cell-cell interaction molecules, and the transcriptional attenuation of MHC class II determinants in somatic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Proliferation of non-Hodgkin-lymphoma lymphocytes in vitro is dependent upon follicular dendritic cell interactions.

Follicular dendritic cells (FDC) are located within the B-cell follicles of non-malignant lymphatic tissues and within non-Hodgkin-lymphomas (NHL) derived from the germinal centre or the mantlezone. The interactions between FDC and non-neoplastic B-cells have been extensively investigated but so far no data on functional studies with FDC isolated from lymphoma tissue are available. Using an enzyme cocktail to digest lymph nodes from patients with NHL followed by density centrifugation, single cell suspensions enriched in FDC and B-lymphocytes were obtained. In these preparations FDC formed small cellular clusters with an average of five neoplastic lymphocytes for every FDC. Immunocytochemistry with Ki67 revealed that after 24 h of culture 23.7% of the cells within the clusters were in late G1 to M phase. In contrast, only 10.2% of the lymphoma cells scattered outside the clusters were in these activated stages. As visualized by autoradiography, after 72 h of incubation the rate of proliferation was 16.8 times higher for the lymphoma cells involved in cluster formation as compared to those lymphocytes not associated with FDC. The data indicate that in vitro FDC from NHL lymph nodes form a microenvironment favourable for the activation and proliferation of lymphoma cells. The search for cytokines secreted by FDC in lymphoma tissue is under way.

Aged↗
PubMed1995

Interleukin-11 stimulates multilineage progenitors, but not stem cells, in murine and human long-term marrow cultures.

Interleukin-11 (IL-11) is a bone marrow microenvironment-derived growth factor with pleiotropic effects on a variety of hematopoietic cells. To more accurately assess the effects of IL-11 on stem and progenitor compartments within the hematopoietic microenvironment (HM), we added recombinant human (rh) IL-11 to human and murine long-term bone marrow cultures (LTMC) and analyzed primitive (high proliferative potential-colony forming cells [HPP-CFC], long-term culture-initiating cells [LTC-IC], and long-term reconstituting stem cells) and progenitor (day 12 colony forming unit-spleen [CFU-S12], colony forming unit-megakaryocyte [CFU-Mk] and colony forming unit-granulocyte/macrophage [CFU-GM]) compartments throughout the duration of the cultures. rhIL-11 (100 ng/mL) added twice weekly resulted in significantly increased nonadherent (NA) cellularity, CFU-GM, and CFU-Mk production in human LTMC. Addition of rhIL-11 to murine LTMC was associated with a 5- to 40-fold increase in CFU-GM and a four- to 20-fold increase in day 12 CFU-S in NA cells. However, IL-11 had no significant effect on total HPP-CFC concentration and decreased the size of the more primitive stem/progenitor compartment as evidenced by both decreased LTC-IC frequency in human LTMC and decreased frequency of long-term reconstituting stem cells in murine LTMC. These data suggest that IL-11 may increase commitment of stem cells into a multipotential progenitor compartment.

Animals↗
PubMed1995

The immune response and the eye. TCR alpha-chain related molecules regulate the systemic immunity to antigen presented in the eye.

Injection of antigen into the anterior chamber (AC) of the eye results in the induction of immune deviation in which antibody production is activated and delayed-type hypersensitivity (DTH) is inhibited. This system is termed anterior chamber associated immune deviation (ACAID) and the model is used to examine certain aspects of the immunologic privilege of the eye. Recent studies have established that following antigen presentation in the eye, an 'ACAID-inducing' signal is produced that directly enters the blood. This signal then homes to the spleen where T cells that down-regulate DTH are activated. For many antigens this 'ACAID signal' is a soluble protein released within 2 days of AC injection. Although the presence of this molecule (or molecules) has been described using several antigens, the exact nature of the soluble mediator has escaped characterization. We have further explored the nature of this signal using HSV-1-induced immune deviation. Our results show the soluble 'signal' was released by T cells that encounter antigen in the ocular microenvironment. This mediator was antigen specific, contained TCR alpha-chain (but not the TCR beta-chain) determinants and had an apparent molecular weight of 46 kDa. These results show that the release of soluble TCR alpha-chain from sites of T cell interaction within the microenvironment of the eye can regulate systemic immune responses. These results have implications for the control of immune response that might be damaging to organs such as the eye.

Animals↗
PubMed2001

Hypoxia regulates osteoblast gene expression.

Vascular disruption secondary to fracture creates a hypoxic gradient of injury wherein the oxygen tension at the center of the wound is very low. In vivo this hypoxic microenvironment stimulates the expression of a variety of cytokines from inflammatory cells, fibroblasts, endothelial cells, and osteoblasts. In order to begin to dissect this complex system, we have examined the effects of hypoxia on isolated osteoblast gene expression in vitro. Understanding gene expression in this system may facilitate the development of targeted therapeutic modalities designed to accelerate fracture repair and reduce complications. Using an established model of in vitro hypoxia, we have analyzed the expression of genes involved in bone matrix production and turnover. Subconfluent neonatal rat calvarial osteoblasts were exposed to hypoxia (pO(2) = 35-40 mm Hg) and total cellular RNA was collected at 0, 3, 6, 24, and 48 h. Northern analysis was used to analyze the expression patterns of (1) transforming growth factors (TGFs)-beta1, -beta2, and -beta3 and their type I receptor; (2) collagens I and III; and (3) tissue inhibitor of metalloproteinase-1. We have demonstrated a marked elevation of TGF-beta1 gene expression within 3 h of hypoxia. Although neither TGF-beta2 nor TGF-beta3 expression was affected by hypoxia, the TGF-beta type I receptor was substantially upregulated within 6 h. In addition, extracellular matrix scaffolding molecules (collagens I and III) were markedly, but differentially, upregulated. Finally, we have demonstrated that the expression of an inhibitor of extracellular matrix turnover, the tissue inhibitor of metalloproteinase-1, was strikingly decreased in response to hypoxia. These results imply that hypoxia can affect osseous healing by altering the expression of cytokines, bone-specific extracellular matrix molecules, and their regulators.

Activin Receptors, Type I↗
PubMed2006

MR imaging of therapy-induced changes of bone marrow.

MR imaging of bone marrow infiltration by hematologic malignancies provides non-invasive assays of bone marrow cellularity and vascularity to supplement the information provided by bone marrow biopsies. This article will review the MR imaging findings of bone marrow infiltration by hematologic malignancies with special focus on treatment effects. MR imaging findings of the bone marrow after radiation therapy and chemotherapy will be described. In addition, changes in bone marrow microcirculation and metabolism after anti-angiogenesis treatment will be reviewed. Finally, new specific imaging techniques for the depiction of regulatory events that control blood vessel growth and cell proliferation will be discussed. Future developments are directed to yield comprehensive information about bone marrow structure, function and microenvironment.

Anti-Inflammatory Agents↗
PubMed2006

Signaling through ERBB receptors: multiple layers of diversity and control.

The four known ERBB receptors in humans are involved in a broad range of cellular responses, and their deregulation is a significant aspect in a large number of disease states. However, their mechanism of action and modes of control are still poorly understood. This is largely due to the fact that the control of ERBB activity is a multilayered process with significant differences between the various ERBB members. In contrast to other receptor tyrosine kinases, the kinase domain of EGFR (ERBB1) does not require phosphorylation for activation. Consequently, the overall activation state of the receptor is controlled by constant balancing of activity favoring and activity suppressing actions within the receptor molecule. Influences of the membrane microenvironment and context dependent interactions with varying sets of signaling partners are superimposed on this system of intramolecular checks and balances. We will discuss current models of the control of ERBB signaling with an emphasis on the multilayered nature of activation control and aspects that give rise to diversity between ERBB receptors.

Endocytosis↗
PubMed2005

Hypoxia and angiogenesis in rheumatoid arthritis.

PURPOSE OF REVIEW: Angiogenesis is a prominent feature of rheumatoid synovitis. Although new blood vessels deliver oxygen to the augmented inflammatory cell mass, the neovascular network is dysfunctional and fails to restore tissue oxygen homeostasis, so that the rheumatoid joint remains a markedly hypoxic environment. The purpose of this review is to discuss the role of hypoxia and angiogenesis in the pathogenesis of rheumatoid arthritis. RECENT FINDINGS: Vascular pathologic change, in the form of angiogenesis, is important in the perpetuation of rheumatoid arthritis and, in the form of endothelial dysfunction, contributes to associated cardiovascular comorbidity. Recent data suggest that tumor necrosis factor-alpha blockade may modify the vascular pathologic changes in rheumatoid arthritis. Angiogenesis is a prominent feature of rheumatoid synovitis. Emerging evidence based on ultrasonographic vascular imaging and angiogenic biomarkers implicates angiogenesis in the active phase of erosive disease. Many factors contribute to the profoundly hypoxic environment that can arise within the joint affected by rheumatoid arthritis. At a cellular level, hypoxia is detected by a mechanism that regulates cytoplasmic concentrations of hypoxia-inducible factor-1alpha. After translocation to the nucleus, hypoxia-inducible factor-1alpha binds its partner hypoxia-inducible factor-1beta to form a heterodimeric, functional transcription factor, hypoxia-inducible factor-1, which activates a gene program associated with angiogenesis, glycolysis, and adaptation to pH. SUMMARY: Despite the luxuriant vasculature associated with rheumatoid arthritis synovitis, the joint affected by rheumatoid arthritis is hypoxic. Repetitive cycles of hypoxia and reoxygenation together with oxidants produced by phagocytic cells promote chronic oxidative stress within the microenvironment of the affected joint, leading to the generation of reactive oxygen species with the potential to contribute to tissue damage.

Arthritis, Rheumatoid↗
PubMed1984

Segregation and characterization of lymphohematopoietic stromal elements.

In the mouse, long-term maintenance of multipotent hematopoietic stem cells in vitro currently requires the establishment of an appropriate adherent layer. When established employing culture medium supplemented with 20% horse serum and 10(-6) M hydrocortisone, the initial adherent layer contains primitive stem cells that are the major contributor of multipotent stem cells (CFUs) assayed subsequently in the supernatant regardless of the addition of fresh bone marrow cells. In contrast, when the adherent layer is established employing 25% fetal calf serum without hydrocortisone, few if any stem cells survive in the adherent layer. Such cultures are dependent upon a recharge with fresh bone marrow as a source of CFUs. A comparison of the latter stem cell-depleted system with the former intact system permits an evaluation of the relative contributions of the adherent layer and stem cells to the long-term maintenance of hematopoiesis in vitro. Studies of the effects of irradiation of the donor animal for the adherent layer and using the intact system demonstrated a reduction in the supernatant CFUs production that was dose- and time-related and evident at doses of 100 and 500 rads. If the adherent layer itself was irradiated immediately before refeeding, a reduction in supernatant CFUs was evident at a dose of 5 rads. These effects, both in vivo and in vitro, cannot be explained solely on the basis of cell killing. Rather, we propose that such doses inactivate, render impotent, or reduce the self-renewal capacity of stem cells that occupy a limited number of "niches" in the adherent layer. Although they are not killed, these impotent stem cells occupy stem cell niches but do not provide an effective contribution of CFUs to the supernatant cells. The adherent layer consists primarily of fibroblasts with significant numbers of macrophages and endothelial cells. The cellular composition of the adherent layer differs between the intact and stem cell-depleted systems in that the latter has a relatively larger proportion of endothelial cells. The composition of the adherent layer influences the type of differentiated cells in the supernatant. The stem cell-depleted adherent layer cultures had a greater proportion of granulocytes among the supernatant cells than macrophages that eventually predominate in the intact system. We have cloned stromal cells from the intact cultures and obtained several stromal cell lines by spontaneous transformation. One of these stromal cell lines (MC1) transfers at least a partial hematopoietic "microenvironment" (granulocytes, macrophages, erythroid cells) to ectopic sites on transplantation to syngeneic recipients.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

IL-1beta induces stabilization of IL-8 mRNA in malignant breast cancer cells via the 3' untranslated region: Involvement of divergent RNA-binding factors HuR, KSRP and TIAR.

IL-8 plays an integral role in promoting the malignant phenotype in breast cancer, and its production is directly influenced by inflammatory cytokines in the tumor microenvironment. Here, we show that activation of IL-1beta receptors on malignant HS578t and MDA-MB-231 breast cancer cells strongly induces IL-8 expression and that RNA stabilization is persistently activated at least 12-24 hr after stimulation. SB 203580 and rapamycin reversed the RNA stabilization effect of IL-1beta in a dose-dependent manner, suggesting involvement of the p38/MAP kinase and mTOR pathways. A luciferase reporter assay indicated that the stabilization effect was dependent on cis elements in the 3'-untranslated region (UTR) of the IL-8 transcript. By UV cross-linking, we identified multiple cellular factors that interact with the IL-8 3'UTR, ranging 34-76 kDa. Immunoprecipitation analysis indicated that HuR, KSRP and TIAR bound to one or more loci in the 3'UTR. While the cross-linking patterns were similar, quantitative immunoprecipitation of native IL-8 RNA from IL-1beta-stimulated cytoplasmic extract revealed a 20-fold greater association of transcript with the stabilizing factor HuR vs. the destabilizing factor KSRP. In conclusion, IL-1beta is a potent cytokine stimulus for IL-8 RNA stabilization in breast cancer cells, possibly by enhanced binding of cytoplasmic HuR to the 3'UTR.

3' Untranslated Regions↗
PubMed1998

Orchiectomy increases bone marrow interleukin-6 levels in mice.

Interleukin-6 (IL-6) appears to be an important factor in disease states associated with bone resorption. There is both in vitro and in vivo evidence supporting the fact that androgens down-regulate interleukin-6 production. These observations, in combination with the fact that osteoblasts and bone marrow stromal cells produce IL-6, led us to hypothesize that orchiectomy-induced androgen loss will result in increased IL-6 expression in the bone microenvironment. To prove our hypothesis we assessed the effect of orchiectomy on IL-6 protein and mRNA expression in bone marrow and spleen. We found that orchiectomy was associated with increased serum IL-6 levels at 3 and 28 days postsurgery. Phorbol ester-stimulated IL-6 levels were also higher in supernatants from bone marrow and spleen cell cultures from orchiectomized mice compared with unoperated or sham-operated mice. Additionally, we found that steady state IL-6 mRNA levels were increased in bone marrow but not spleen cells. Finally, we found that orchiectomized mice had splenomegaly and increased bone marrow cellularity. Histopathology of the spleen revealed lymphoid hyperplasia accompanied by a marked mononuclear cell infiltration of the red pulp. We conclude that orchiectomy induces IL-6 expression in the bone marrow. These findings suggest that endocrine and cytokine interactions contribute to bone pathophysiology.

Animals↗
PubMed2005

Bcl-x(L)-mediated changes in metabolic pathways of breast cancer cells: from survival in the blood stream to organ-specific metastasis.

Bcl-x(L) protein plays a role in breast cancer dormancy, promoting survival of cells in metastatic foci by counteracting the proapoptotic signals in the microenvironment. The aim of this study was to identify phenotypes mediated by Bcl-x(L) in breast cancer cells that enhance in vivo survival of clinical metastases. 435/Bcl-x(L) or 435/Neo human breast cancer cells were injected into the inguinal mammary gland of nude mice, and tumors, metastases in lymph node, lung, and bone, and bloodstream surviving cells were examined. Proteomic analysis identified 17 proteins that were overexpressed (more than twofold) or underexpressed (less than twofold) in metastases. A protein interaction program allowed us to functionally associate peroxiredoxin 3, peroxiredoxin 2, carbonyl reductase 3, and enolase 1, suggesting a role for cellular responses to oxidative stress in metastasis organ selection. The prediction included proteins involved in redox systems, kinase pathways, and the ATP synthase complex. Furthermore, the interaction of redox proteins with enolase 1 suggests a connection between glycolysis and antioxidant pathways, enabling achievement of a high metastatic activity. In conclusion, Bcl-x(L) mediates a phenotype in which redox pathways and glycolysis are coupled to protect breast cancer metastatic cells during transit from the primary tumor to the metastatic state.

Animals↗
PubMed1979

Studies on the resistance to tolerance induction against human IgG in DDD mice. II. Tolerogen-resistant T-cell population in the spleen.

Further studies were carried out to investigate cellular sites of the resistance to the induction of immunological tolerance to HGG in DDD mice, assuming the presence of a subset of tolerogen-resistant splenic T cells. Spleen-seeking T cells were shown to be relatively resistant in comparison with lymph node-seeking T cells. The existence of a tolerogen-resistant T-cell subpopulation was indicated from the experiments demonstrating that tolerance was easily attained after adult thymectomy and that lymph node T cells became much more resistant to tolerance induction after adult splenectomy. The latter experimental result might also exclude the possibility of differences in microenvironment (probably in A cells) between spleen and lymph node. An attempt was made to investigate a possible involvement of A cells in the induction of tolerance. A cells were deprived in vivo by irradiation of the host 3 days prior to spleen cell transfer and in vitro by passing a spleen cell suspension through a Sephadox G-10 column. The deprivation of A cells resulted in priming of the host by the tolerogen rather than easier tolerance induction. No suppressive activity was observed in lymph node cells from tolerized mice. These results suggest that there exists a set of T cells, generated relatively recently in the thymus, preferentially migrating into spleen and there becoming resistant to tolerance induction.

Animals↗