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PubMed1998

Enzyme compartmentalization during biphasic enamel matrix processing.

Processing of enamel matrix proteins is essentially biphasic. Secretory stage metalloprotease activity generates a discrete, presumably functional, spectrum of molecules which may also undergo dephosphorylation. Maturation stage serine proteases almost completely destroy the matrix. The present aim was to examine the tissue compartmentalization of these enzyme activities in relation to their possible function. A sequential extraction using synthetic enamel fluid, phosphate buffer and SDS was used to identify enzymes free in the enamel fluid, crystal bound or aggregated with the bulk matrix respectively. Results indicated that the metallo-proteases and alkaline phosphatase were free in the secretory stage enamel fluid while the serine proteases appeared to be largely bound to the maturation stage crystals. The mobility of the metallo-proteases and alkaline phosphatase would ensure efficient initial processing of secretory matrix, while the largely mineral bound serine proteases would ensure retention of protease activity despite massive destruction and protein removal.

Animals↗
PubMed1989

A compartmentalized device for the culture of animal cells.

A simply-constructed device for the batch culture of animal cells is described that takes advantage of gas-permeable polymer films and continuous dialysis of nutrient fluids. The design separates a cell-growth chamber from a nutrient-medium reservoir with a dialysis membrane, effectively compartmentalizing growth and feeding functions. Resulting culture environment is extraordinarily stable since frequent medium exchanges are not required and macromolecules biosynthesized by cells are retained within the cell-growth compartment. Culture experiments with a variety of mammalian cells (epithelioid, fibroblastic, hybridoma, primary murine) are described that demonstrate unattended culture for up to 30 days. Immunoglobulin (IgG) secreted by cultured hybridoma cells concentrated in the growth compartment more than 25-fold over levels attained at confluence in conventional flasks. Applications for the device in various areas using animal cell culture and potential advantages in scale are discussed.

Animals↗
PubMed1976

Oral fructose tolerance, gastric emptying and absorption: a compartmental model.

Gastric emptying and intestinal absorption regulate transfer of ingested fructose from stomach to plasma. Using conscious rhesus monkeys we have developed a compartmental model which describes this system. Fructose tolerance tests were performed in groups of monkeys by intragastrically administering 2 g/kg of 10.5% D-fructose solution; fructose concentration in arterial plasma, [fructose], and intragastric volume were measured at intervals afterward. One group was pretreated with atropine; stomachs imptied with a time constant, tau, of 67 min. Another group received fructose solution with trisodium citrate added; tau was 18 min. Another group received only fructose; tau was 30 min. Using these constants, a model was developed to describe the [fructose] data. In this model k1 related amount of fructose in intestine to absorption rate and Ae represented absorption efficiency. K1 = 0.03 and Ae = 89% provided a good fit for data from the atropinized group. k1 = 0.018 and Ae = 56% provided a good fit for data from the other groups. Differences were explained by considering effects of atropine on gastrointestinal secretion. The model adequately describes our [fructose] data and may be adapted for tests utilizing other substances.

Animals↗
PubMed1980

Compartmentalization of the cerebral ventricles as a sequela of neonatal meningitis.

Thirteen infants with compartmentalization of the lateral ventricles diagnosed by air encephalography, computerized tomography, or autopsy are reported. In each case, the body of one or both lateral ventricles was completely divided by a membrane posterior to the foramen of Monro. Recognition of this entity is important from both therapeutic and prognostic standpoints.

Brain Diseases↗
PubMed2000

Cutting edge: selective IL-18 requirements for induction of compartmental IFN-gamma responses during viral infection.

Optimal protective effects for defense against infection require orchestration of immune responses spanning multiple host compartments and divergent local regulation at particular sites. During murine cytomegalovirus infections known to target spleen and liver, IL-12-induced IFN-gamma from NK cells is crucial for resistance. However, the roles for IL-18 and/or IL-12 in regulating hepatic IFN-gamma responses, as compared with systemic or splenic responses, have not been defined. In this report, mice genetically deficient in either IL-18 or IL-12p35 exhibited up to 95% reductions in systemic and splenic IFN-gamma responses. Surprisingly, IFN-gamma responses were preserved in the livers of IL-18-deficient, but not IL-12p35-deficient, mice. Cytokine requirements for host survival also differed. Under conditions where mice lacking IL-12p35 exhibited 100% mortality, those lacking IL-18 survived. Taken together, our results delineate contrasting compartmental requirements for IL-18 and suggest that preservation of local, hepatic IFN-gamma production is critical for host defense during murine cytomegalovirus challenge.

Animals↗
PubMed2001

Compartmentalization of Peyer's patch anlagen before lymphocyte entry.

We have shown that Peyer's patch (PP) first develops as a simple and even cell aggregation during embryogenesis. To investigate when and how such a simple cell aggregation forms the complex PP architecture, we analyzed the distribution of cells expressing IL-7R alpha (PP inducer cells), VCAM-1 (mesenchymal cells), CD11c (dendritic cells), and mature lymphocytes by whole-mount immunostaining of 17.5 days post coitus to 2 days postpartum mouse gut. Our results show that compartmentalization of PP anlagen commences at day 18.5 of gestation by clustering and subsequent follicle formation of IL-7R alpha(+), VCAM-1(+), and CD11c(+) cells. This process adds the primitive architecture of PP anlage with several follicles in which IL-7R alpha(+) cells localize in the center, while VCAM-1(+) and CD11c(+) cells localize at the fringe. This follicle formation is accompanied by the establishment of PP-specific vascular network expressing mucosal addressin cellular adhesion molecule-1. Mature B and T lymphocytes entering in the PP anlage are distributed promptly to their own target zones; B cells to the follicle and T cells to nonfollicular zones. Our analysis of scid/scid mouse indicate that the initial processes including formation of PP-specific vascular network occur in the absence of lymphocytes. These observations indicate that the basic architecture of PP is formed by a set of cell lineages assembled during the initial phase of induction of PP anlagen before entry of mature lymphocytes.

Animals↗
PubMed2002

Development and compartmentalization of the porcine TCR delta repertoire at mucosal and extraintestinal sites: the pig as a model for analyzing the effects of age and microbial factors.

gammadelta T cells are an important component of the mucosal immune system. Previously, we have shown that the TCR delta repertoire in human intestine is polyclonal at birth and becomes increasingly restricted with age. In this study, we expand those studies to the pig which allows more extensive experiments including several organs. Tissues from different mucosal sites like the stomach, duodenum, ileum, Peyer's patches, jejunum, and colon, and also extraintestinal sites like the lung, spleen, thymus and mesenteric lymph nodes, were obtained from conventionally reared pigs aged 2 wk to 5.5 years. In addition, tissues were also obtained from 10-wk-old specified pathogen- and germ-free pigs. TCRDV1-DV5 transcripts were amplified by RT-PCR after which complementarity-determining region 3 spectratyping was performed. Individual bands were excised from the gels and directly sequenced. The intestinal TCR delta repertoire showed increasing restriction with age and was highly oligoclonal in the adult 2- to 5.5-year-old pigs. In old pigs, we observed a striking compartmentalization. Different TCR delta repertoires were present between the lungs and the intestinal mucosa but also within different parts of the gastrointestinal tract. However, occasionally we observed identical TCR delta transcripts in the intestine and the lungs and shared clones could be detected also along the entire gastrointestinal tract. Thus, subsets of gammadelta T cells are likely to transport immunological information between different compartments of the immune system. Furthermore, these data support the hypothesis that in each mucosal site, different Ags are responsible for selecting and maintaining the gammadelta TCR over time.

Aging↗
PubMed2003

The induction and kinetics of antigen-specific CD8 T cells are defined by the stage specificity and compartmentalization of the antigen in murine toxoplasmosis.

Toxoplasma gondii forms different life stages, fast-replicating tachyzoites and slow-growing bradyzoites, in mammalian hosts. CD8 T cells are of crucial importance in toxoplasmosis, but it is unknown which parasite stage is recognized by CD8 T cells. To analyze stage-specific CD8 T cell responses, we generated various recombinant Toxoplasma gondii expressing the heterologous Ag beta-galactosidase (beta-gal) and studied whether 1) secreted or cytoplasmic Ags and 2) tachyzoites or bradyzoites, which persist intracerebrally, induce CD8 T cells. We monitored the frequencies and kinetics of beta-gal-specific CD8 T cells in infected mice by MHC class I tetramer staining. Upon oral infection of B6C (H-2(bxd)) mice, only beta-gal-secreting tachyzoites induced beta-gal-specific CD8 T cells. However, upon secondary infection of mice that had received a primary infection with tachyzoites secreting beta-gal, beta-gal-secreting tachyzoites and bradyzoites transiently increased the frequency of intracerebral beta-gal-specific CD8 T cells. Frequencies of splenic and cerebral beta-gal-specific CD8 T cells peaked at day 23 after infection, thereafter persisting at high levels in the brain but declining in the spleen. Splenic and cerebral beta-gal-specific CD8 T cells produced IFN-gamma and were cytolytic upon specific restimulation. Thus, compartmentalization and stage specificity of an Ag determine the induction of CD8 T cells in toxoplasmosis.

Animals↗
PubMed2003

Strategic compartmentalization of Toll-like receptor 4 in the mouse gut.

Pattern recognition receptors (PRRs), which include the Toll-like receptors (TLRs), are involved in the innate immune response to infection. TLR4 is a model for the TLR family and is the main LPS receptor. We wanted to determine the expression of TLR4 and compare it with that of TLR2 and CD14 along the gastrointestinal mucosa of normal and colitic BALB/c mice. Colitis was induced with 2.5% dextran sodium sulfate (DSS). Mucosa from seven segments of the digestive tract (stomach, small intestine in three parts, and colon in three parts) was isolated by two different methods. Mucosal TLR4, CD14, TLR2, MyD88, and IL-1beta mRNA were semiquantified by Northern blotting. TLR4 protein was determined by Western blotting. TLR4/MD-2 complex and CD14 were evaluated by immunohistochemistry. PRR genes were constitutively expressed and were especially stronger in colon. TLR4 and CD14 mRNA were increased in the distal colon, but TLR2 mRNA was expressed more strongly in the proximal colon, and MyD88 had a uniform expression throughout the gut. Accordingly, TLR4 and CD14 protein levels were higher in the distal colon. TLR4/MD-2 and CD14 were localized at crypt bottom epithelial cells. TLR4/MD2, but not CD14, was found in mucosal mononuclear cells. Finally, DSS-induced inflammation was localized in the distal colon. All genes studied were up-regulated during DSS-induced inflammation, but the normal colon-stressed gut distribution was preserved. Our findings demonstrate that TLR4, CD14, and TLR2 are expressed in a compartmentalized manner in the mouse gut and provide novel information about the in vivo localization of PRRs.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Compartmental imbalance and aberrant immune function of blood CD123+ (plasmacytoid) and CD11c+ (myeloid) dendritic cells in atopic dermatitis.

Atopic dermatitis (AD) is a pruritic, chronically relapsing skin disease in which Th2 cells play a crucial role in cutaneous and extracutaneous immune reactions. In humans, CD11c+CD123- myeloid dendritic cells (mDC) and CD11c-CD123+ plasmacytoid DC (pDC) orchestrate the decision-making process in innate and acquired immunity. Since the number and function of these blood dendritic cell (DC) subsets reportedly reflect the host immune status, we studied the involvement of the DC subsets in the pathogenesis of AD. Patients with AD had an increased DC number and a low mDC:pDC ratio with pDC outnumbering mDC in the peripheral blood compared with normal subjects and psoriasis patients (a Th1 disease model group). The mDC:pDC ratio was correlated with the total serum IgE level, the ratio of IFN-gamma-producing blood cells:IL-4-producing blood cells, and the disease severity. In vitro allogeneic stimulation of naive CD4+ cells with atopic DC showed that the ability of pDC for Th1 induction was superior or comparable to that of mDC. In skin lesions, pDC infiltration was in close association with blood vessels expressing peripheral neural addressins. Therefore, compartmental imbalance and aberrant immune function of the blood DC subsets may deviate the Th1/Th2 differentiation and thus induce protracted allergic responses in AD.

Adolescent↗
PubMed2005

Interpretation of absorption rate data for inhaled fluticasone propionate obtained in compartmental pharmacokinetic modeling.

OBJECTIVE: Reports characterizing the pharmacokinetics of inhaled fluticasone propionate (FP) using compartmental approaches have suggested that the absorption of FP into the systemic circulation is rapid with a half-life of approximately 10 min. We believe that this is a classical case of misassignment of the pharmacokinetic parameter estimates, a problem often encountered while modeling pharmacokinetic data. The objective of this study was to illustrate and analyze this problem using actual blood level data of FP obtained in 14 healthy subjects. MATERIALS AND METHODS: Serum concentration-time data of FP were obtained from a double-blind, randomized study involving single and multiple twice-daily inhalations of 500 microg via a dry powder device, Diskus. The profiles were fitted using one- and two-compartment pharmacokinetic models with first order absorption. Various permutations of the resulting exponential rate constants were analyzed to determine the combination that was most consistent with the underlying physical process. RESULTS: The two-compartment body model with first order absorption gave excellent fits for the observed FP concentrations after both single and multiple dosing. Even though peak levels were reached relatively early (30 - 90 min) after inhalation, the combination that most appropriately described the underlying process was alpha > Ka > beta, i.e. slow absorption, rapid distribution and slower elimination kinetics. The absorption, distribution and elimination half-lives resulted to be 3.8 h, 9.9 min and 13.6 h, respectively, consistent with the high lipophilicity and sustained dissolution characteristics observed in vitro. CONCLUSIONS: Analysis of FP pharmacokinetics after inhalation represents a classical case of potential misassignment of the exponential rate constants, which if ignored, could lead to erroneous interpretations regarding the underlying process. The study also elucidates the pitfall of using t(max) to calculate absorption rate.

Absorption↗
PubMed1977

Effect of rifampicin derivatives on the ion compartmentation of biological membranes.

Based on the experimental results that 3-formyl rifamycin SV acts as an uncoupler in vitro on rat liver mitochondria, the effect of some rifampicin derivatives on the K+ and H+ compartmentation of biological membranes was examined to obtain a chemiosmotic hypothesis for oxidative phosphorylation. The K+ release from mitochondria was remarkably stimulated by 3-formyl rifamycin SV in accordance with uncoupling of the oxidative phosphorylation. 3-Formyl rifamycin SV also stimulated the K+ release from red blood cells, though its action was not as effective as in mitochondria. It can be suggested that 3-formyl rifamycin SV interacts with biological membranes, causing a change in permeability to ions, especially of K+ and H+ through the mitochondrial membrane, resulting in uncoupling of the oxidative phosphorylation.

Animals↗
PubMedDate not supplied

[A compartmental approach in modeling a neuronal network. Role of inhibitory and excitatory processes].

The conception and main principles of the compartmental approach to the modeling of neuronal networks are presented. Excitatory and inhibitory ties are described, and reducible and nonreducible neuronal networks are considered. The periodical solution in models of neuronal networks is the model of normal rhythmic (e.g., respiratory) activity. The role of external (chemoreceptor drives) is discussed. The biological interpretation of the results of modeling is given. The observed biological phenomena are considered.

Models, Biological↗
PubMed2000

Stoichiometry and compartmentation in G protein-coupled receptor signaling: implications for therapeutic interventions involving G(s).

There is great therapeutic interest in manipulating (either enhancing or suppressing) G protein-coupled receptor (GPCR) signal transduction. However, most current strategies are limited to pharmacological activation or blockade of receptors. Human gene therapy, including both overexpression and antisense approaches, may allow manipulation of GPCR signaling at steps distal to receptors. To fully understand the impact of such therapy, the transduction of signals between the multiple components of GPCR signaling and their interaction with other cellular molecules must be understood in the context of both normal physiology and disease. Defining the stoichiometric relationship among multiple components of GPCR signaling is a first step. We summarize data showing the substantial excess of G(alphas) relative to both beta-adrenergic receptors and adenylyl cyclase. A predominant idea regarding signaling via GPCRs has for over 20 years emphasized the concept of random movement and collision ("collision coupling") of proteins within the lipid bilayer of the plasma membrane. This notion does not readily account for the rapidity and fidelity of signal transduction by the multiple components involved in GPCR-G protein-effector systems, especially considering the low abundance of these proteins in cells. Recently, many components involved in signal transduction by GPCRs have been shown to exist primarily in microdomains of the plasma membrane, in particular, caveolae. These and other structures may serve to compartmentalize signals, thereby optimizing signal transduction between an agonist and specific effectors. The formation, organization, and maintenance of such structures may prove to be altered in disease states associated with disregulated signaling. In addition, we speculate that identification of genetic polymorphisms of and therapy targeted to components that are critical for determining efficacy (e.g., effectors such as adenylyl cyclase) will provide important future therapeutic strategies.

Adenylyl Cyclases↗
PubMed2000

Functional compartmentalization of opioid desensitization in primary sensory neurons.

The cellular correlates of desensitization or tolerance are poorly understood. To address this, we studied acute and long-term mu-opioid desensitization, with respect to Ca(2+) currents, in cultured rat dorsal root ganglion (DRG) neurons. Exposure of DRG neurons to the mu-agonist [D-Ala(2),N-MePhe(4), Gly-ol(5)]-enkephalin (DAMGO; 3 microM) reduced whole-cell currents approximately 35%, but with continued agonist application, 52% of the response was lost over 10 to 12 min. In contrast, exposure of DRG neurons to DAMGO for 24 h resulted in a nearly complete loss of Ca(2+) channel regulation after washing and re-exposure to DAMGO. Responses to the gamma-aminobutyric acid(B) agonist baclofen were not affected in these neurons. Acute desensitization preferentially affected the voltage-sensitive component of mu-opioid and gamma-aminobutyric acid(B) responses. Facilitation of both the DAMGO- and baclofen-inhibited current by a strong depolarizing prepulse was significantly attenuated in acutely desensitized neurons. Because G(betagamma)-subunits mediate neurotransmitter-induced changes in channel voltage-dependent properties, these data suggest an altered interaction of the G(betagamma)-subunit with the Ca(2+) channel. Block of N-type Ca(2+) channels with omega-conotoxin GVIA revealed a component of the opioid response that did not desensitize over 10 min. We conclude that acute and long-term mu-opioid desensitization in DRG neurons occurs by different mechanisms. Acute desensitization is heterologous and functionally compartmentalized: the pathway targeting non-N-type channels is relatively resistant to the early effects of continuous agonist exposure; the pathway targeting N-type channels in a largely voltage-insensitive manner is partially desensitized; and the pathway targeting N-type channels in a largely voltage-sensitive manner is completely desensitized.

Analgesics, Opioid↗
PubMed1998

[Compartmental distribution of hepatitis C virus quasispecies in mononuclear cells and liver].

OBJECTIVE: To explore the role of the infection of monouclear cells by hepatitis C virus(HCV) in the chronicity of HCV infection. METHODS: Direct sequencing of the amplified hypervariable region (HVR) gene of HCV was used to distinguish main HCV quasispecies infecting non-hepatocytes from those infecting hepatocytes and circulating virions. The main HCV quasispecies in peripheral blood mononuclear cells(PBMC), liver-associated mononuclear cells (LAMC), serum and liver samples from 6 patients with chronic hepatitis C and from 6 patients with HCV-related cirrhosis were analysed and compared. RESULTS: The main HCV qusispecies in the livers were different from those in PBMC in 3 transplanted cirrhotic patients and 5 patients with chronic hepatitis C. Different substitutions existed between PBMC and LAMC in 3 of 6 patients analysed. Mutations were observed within the first 50 amino acids of E2 gene, which induced amino acid change in 6 of 9 patients analysed. CONCLUSION: In chronically infected patients, the detection of HCV RNA in mononuclear cells is not due to the adsorption of circulating virions but a significant infection. The compartmental distribution of HCV quasispecies in hepatocytes and mononuclear cells could be involved in the chronicity of HCV infection.

Amino Acid Sequence↗
PubMed2000

General compartmental models of the cardiovascular system.

A systematic discussion on linear as well as non-linear compartmental models of the cardiovascular system and its various feedback mechanism is given. Most of the results are independent of explicit functional expressions. The topological structure of the model is essential for the response to a local change in peripheral resistance. Inclusion of Parallel paths versus serial paths gives qualitatively different response. Global asymptotic stability follows from the general theory.

Baroreflex↗
PubMed2000

Subcellular compartmentalization of a potassium channel (Kv1.4): preferential distribution in dendrites and dendritic spines of neurons in the dorsal cochlear nucleus.

Voltage-dependent ion channels have specific patterns of distribution along the neuronal plasma membrane of dendrites, cell bodies and axons, which need to be unravelled in order to understand their contribution to neuronal excitability and firing patterns. We have investigated the subcellular compartmentalization of Kv1.4, a transient, fast-inactivating potassium channel, in fusiform cells and related interneurons of the rat dorsal cochlear nucleus. A polyclonal antibody which binds to a region near the N-terminus domain of a Kv1.4 channel was raised in rabbits. Using a high-resolution combination of immunocytochemical methods, Kv1.4 was localized mainly in the apical dendritic trunks and cell bodies of fusiform cells, as well as in dendrites and cell bodies of interneurons of the dorsal cochlear nucleus, likely cartwheel cells. Quantitative immunogold immunocytochemistry revealed a pronounced distal to proximal gradient in the dendrosomatic distribution of Kv1. 4. In plasma membrane localizations, Kv1.4 was preferentially present in dendritic spines, either in the spine neck or in perisynaptic locations, always away from the postsynaptic density. These findings indicate that Kv1.4 is largely distributed in dendritic compartments of fusiform and cartwheel cells of the dorsal cochlear nucleus. Its preferential localization in dendritic spines, where granule cell axons make powerful excitatory synapses, suggests a role for this voltage-dependent ion channel in the regulation of dendritic excitability and excitatory inputs.

Amino Acid Sequence↗