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PubMed1993

Nuclear compartmentalization in transcriptionally activated hypothalamic neurons.

Transcription of cell-specific vasopressin and oxytocin genes as well as transcription of those housekeeping genes responsible for general metabolic activation and cellular hypertrophy is induced in supraoptic hypothalamic neurons by rises in plasma osmolarity. In this study, the nuclear volume, the ultrastructure of chromatin and the number and distribution of nuclear particles in the cell nuclei of supraoptic neurons of 3-month-old male Sprague-Dawley rats were analyzed after osmotically induced activation of transcription by periods of acute (1 day) and chronic (6 days) dehydration, and after halting the stimulation by rehydration of animals. The nuclear volume and the ultrastructure of chromatin were assessed on ultrathin sections. The number and distribution of nuclear particles were assessed on freeze-fracture replicas. The initial phase of osmotically induced enhancement of transcription was accompanied by an increase in nuclear volume and by a partial replacement of nuclear particles of large diameter (> 11 nm) by smaller nuclear particles. This latter change affected predominantly the nuclear periphery (0-1,000 nm from the nuclear membrane) and occurred simultaneously with a partial decondensation of chromatin clusters that may be related to chromatin unfolding. In chronically stimulated animals, the decondensation of chromatin and the replacement of large nuclear particles by smaller ones was enhanced in the nuclear periphery and was partially propagated to the interior of the nucleus. After suppression of cellular activation by rehydration of animals, the number of nuclear particles returned to control levels in the nuclear periphery while in the center of the nucleus the number of small particles decreased and the number of large particles increased as compared to control values. These results, together with the observation that in unstimulated cells the nuclear periphery and the nuclear interior differ in their composition of nuclear particles, evidence a structural and functional compartmentalization in the cell nucleus of supraoptic neurons.

Animals↗
PubMed1998

The distribution and intracellular compartmentation of metals in the endogeic earthworm Aporrectodea caliginosa sampled from an unpolluted and a metal-contaminated site.

The tissue distribution of Cd, Cu, Pb, Zn and Ca in the endogeic earthworm Aporrectodea caliginosa living in a non-polluted and a heavy metal polluted soil was investigated. The tissues of animals from the contaminated soil contained greater concentrations of Cd, Pb and Zn than the corresponding tissues of animals from the unpolluted soil. The greatest concentrations of Cd, Pb, Zn, and Ca were primarily accumulated within the posterior alimentary canal (PAC), a tissue fraction which contained the greatest proportion of the whole-worm burdens of the respective metals. Cu was distributed fairly evenly in the tissue fractions investigated. The pattern of accumulation for the 'heavy' metals is broadly similar to that for epigeic earthworms; in contrast, a different pattern of tissue accumulation was found for Ca. In animals from the uncontaminated site, the major elemental constituents of the chloragosomes were P, Ca, Zn and S. A significant positive correlation exists between P and Ca within the chloragosomal matrix. These intracellular vesicles are major foci for Pb and Zn accumulation within the PAC, with 'excess' metals associated with P ligands within the chloragosome matrix. The incorporation of Pb and Zn appears to involve the cationic displacement of Ca. Such compartmentation appears to prevent dissemination of large concentrations of these metals into other earthworm tissues, and may thus represent a detoxification strategy based on accumulative immobilization. No intracellular localization of Cd was identified in the study, although the Cd concentration in the metalliferous soils examined was not exceptionally high. The observations are discussed in the context of a contribution to enhanced understanding of metal ecotoxicology in earthworms by providing baseline data on a little investigated ecophysiological group of earthworms. Comparisons of metal distribution and mechanisms of metal sequestration are made with other ecophysiological groups of earthworms, and the significance of the findings to biomonitoring and toxicity-testing programmes is considered.

Journal Article↗
PubMed1986

Estimation of compartmentation of lysine inside the cells of Yarrowia lipolytica.

We studied the compartmentation of lysine in vivo by the tracer method of Subramanian et al. (J. Bacteriol. 115 (1973) 284-290). To calculate the size of the different lysine pools and lysine fluxes inside the cell, a mathematical model was designed enabling quantitative estimation of these data from experimental measurements. This technique was applied to a lysine-accumulating strain, 15901.7, and to its low lysine pool derivatives, ply-1, ply-4 and ply-9, which were selected for their low polyphosphate pools. In the mother strain, 15901.7, it appeared that lysine was stored mainly in a non-cytoplasmic compartment. In the mutants, the efflux from this compartment was higher and accounted for the higher percentage of lysine in the cytoplasm of these strains. Simulation with calculated parameters fitted the experimental curves very well. This was good evidence for the pertinence of the model. The biological significance of these results are discussed.

Cytoplasm↗
PubMed2001

Time course equations of the amount of substance in a linear compartmental system and their computerized derivation.

In this contribution, we present the symbolic time course equations corresponding to a general model of a linear compartmental system, closed or open, with or without traps and with zero input. The steady state equations are obtained easily from the transient phase equations by setting the time --> infinity. Special attention has been given to the open systems, for which an exhaustive kinetic analysis has been developed to obtain important properties. Besides, the results have been particularized to open systems without traps and an alternative expression for the distribution function of exit times has been provided. We have implemented a versatile computer program, that is easy to use and with a user-friendly format of the input of data and the output of results. This computer program allows the user to obtain all the information necessary to derive the symbolic time course equations for closed or open systems as well as for the derivation of the distribution function of exit times.

Computer Simulation↗
PubMed1996

Phosphoinositide-derived diacylglycerol conversion to phosphatidic acid is a receptor-dependent and compartmentalized phenomenon in human neuroblastoma.

We report that upon muscarinic stimulation of SK-N-BE(2) human neuroblastoma cells, the extent of phosphoinositide-derived diacylglycerol (DG) conversion to phosphatidic acid (PA), operated by a DG kinase, is dependent on the potency of receptor stimulation and correlates with the reduction of phosphatidylinositol 4,5-bisphosphate mass. Evidence is provided that agonist-evoked Ca2+ mobilisation or protein kinase activation are not key events in triggering receptor-generated DG conversion to PA; furthermore, the phenomenon is compartmentalized, namely it occurs within a topologically restricted area that is poorly accessible to DG artificially generated by cell treatment with bacterial phosphatidylinositol-specific phospholipase C. Possible mechanisms driving regulation of the DG kinase operating in the transduction system investigated are discussed.

Carbachol↗
PubMed1997

Lactate formation from [U-13C]aspartate in cultured astrocytes: compartmentation of pyruvate metabolism.

Metabolism of [U-13C]aspartate in cultured astrocytes and the effects of inhibitors of malic enzyme and phosphoenolpyruvate carboxykinase (hydroxymalonate and 3-mercaptopicolinic acid, respectively) were studied using 13C nuclear magnetic resonance (NMR) spectroscopy. The labelling of glutamate and glutamine showed entry of aspartate into the tricarboxylic acid (TCA) cycle after conversion to oxaloacetate. Production of [U-13C]pyruvate from [U-13C]aspartate was revealed by the presence of [U-13C]lactate in incubation media. Furthermore, labelling patterns in C-2 and C-3 in intracellular aspartate showed entry of [1,2-13C]acetyl-CoA into the TCA cycle; evidence for pyruvate-recycling. No reduction in [U-13C]lactate was observed in the presence of either enzyme inhibitor. However, 3-mercaptopicolinic acid reduced incorporation of labelled acetyl-CoA into TCA cycle intermediates, indicating compartmentation of pyruvate production in astrocytes.

Animals↗
PubMed1998

High resolution immunogold analysis reveals distinct subcellular compartmentation of protein kinase C gamma and delta in rat Purkinje cells.

High resolution immunogold cytochemistry was used to investigate the subcellular distribution of protein kinase C gamma and delta in Purkinje cells of the rat cerebellum. Postembedding incubation with an antibody raised to a peptide sequence near the C-terminus of protein kinase C gamma resulted in strong labelling along the dendrosomatic plasma membrane. A quantitative analysis indicated that this labelling reflected the existence of two pools of protein kinase C gamma; one membrane associated pool and one cytoplasmic pool located within 50 nm of the plasma membrane. The labelling along the plasma membrane showed a pronounced and abrupt increase when moving from the cell body into the axon initial segment. Gold particles signalling protein kinase C gamma were also enriched in putative Purkinje axon terminals in the dentate nucleus. The only organelle showing a consistent immunolabelling for protein kinase C gamma was the Golgi apparatus where the gold particles were restricted to the trans face. Protein kinase C gamma immunoreactivity also occurred in the Purkinje cell spines, with an enrichment in or near the postsynaptic density. Antibodies to protein kinase C delta produced a very different labelling pattern in the Purkinje cells. Most of the gold particles were associated with rough endoplasmic reticulum, particularly with those cisternae that were located close to the nucleus or in the nuclear indentations. No significant protein kinase C delta immunolabelling was detected at the plasma membrane or in Purkinje cell spines. The present data point to a highly specific compartmentation of the two major protein kinase C isozymes in Purkinje cells and suggest that these isozymes act on different substrates and hence have different regulatory functions within these neurons.

Animals↗
PubMed1998

Differential compartmentalization of brain ascorbate and glutathione between neurons and glia.

Compartmentalization of brain ascorbate and glutathione between neurons and glia has been a source of controversy. To address this question, we determined the ascorbate and glutathione contents of brain tissue with defined, but varying, densities of neurons and glia. In developing rat cortex and hippocampus, glutathione content rose during gliogenesis, while ascorbate fell. By contrast, ascorbate, but not glutathione, increased markedly during granule cell proliferation and maturation in the developing cerebellum. Similarly, in tissue from adult cerebral cortex of species with distinct neuron densities, ascorbate content increased linearly with increasing neuron density in the order: human<rabbit<guinea-pig<rat<mouse, whereas glutathione was relatively constant. These data suggest that ascorbate predominates in neurons, whereas glutathione is slightly predominant in glia. Quantitative analysis of ascorbate and glutathione contents in these studies combined with appropriate intra- and extracellular volume fraction data permitted calculation of concentrations of ascorbate in neurons (10 mM) and glia (0.9 mM), and glutathione in neurons (2.5 mM) and glia (3.8 mM). The relative accuracy of these values was confirmed by their use in a model that reliably predicted changes in ascorbate and glutathione levels in rat cortex during the first three postnatal weeks and into adulthood. These findings not only provide new information about the intracellular composition of neurons and glia, but also have implications for understanding the roles of ascorbate and glutathione in normal brain function, as well as neuron and glia involvement in disease states linked to oxidative stress.

Aging↗
PubMed1999

Compartmental expression of trkB receptor protein in the developing striatum.

To investigate the role of neurotrophins in the initial formation of striatal patch versus matrix, the spatial and temporal expression of trkB receptors was examined using immunohistochemistry. Polyclonal antibodies, against the C-terminus or the tyrosine kinase domain, revealed trkB-immunoreactive cells and fibers localized to patches beginning on embryonic day 19 in the rat, which co-localized with patchy dopamine fibers, substance P-immunoreactive neurons and glutamate receptors. Patchy striatal trkB expression was maintained after lesioning the nigrostriatal dopamine system. The patchy trkB distribution persisted through postnatal day 14, then became more homogeneous at the same time that nigrostriatal afferents become homogeneous. Later in development, trkB immunoreactivity was most intense in a subpopulation of large striatal cells that were similar in size and frequency to those immunoreactive for choline acetyltransferase. The spatiotemporal expression of trkB receptor in phenotypically distinct striatal patches, as well as evidence that neurotrophins regulate expression of neuronal phenotypic markers during development, may indicate a convergence of neurotrophins and afferent innervation on to future patch cells that may regulate the establishment of striatal compartmentalization.

Aging↗
PubMed1999

Changes in the regional and compartmental distribution of FosB- and JunB-like immunoreactivity induced in the dopamine-denervated rat striatum by acute or chronic L-dopa treatment.

This study was carried out in order to examine the effects of acute or chronic L-DOPA treatment on striatally expressed FosB- and JunB-like proteins in a rat model of Parkinson's disease. Rats with a unilateral, near-total 6-hydroxydopamine lesion of the ascending mesostriatal projection received either an acute challenge or a one-week treatment with 10 mg/kg/day methyl L-DOPA (combined with 15 mg/mg benserazide), and were killed at either 3 h or two days post-injection. Both acute and chronic L-DOPA treatment caused a pronounced, persistent increase in the number of FosB-like immunoreactive cells in the dopamine-denervated striata (five- and seven-fold increase, respectively, above the levels found in lesioned but non-drug-treated controls), but the two treatment groups differed markedly with respect to both the average amount of staining per cell, which was two-fold larger in the chronic L-DOPA cases, and the anatomical distribution of the labeled cells. After an acute injection of L-DOPA, FosB-positive cells were distributed rather uniformly across all striatal subregions, whereas chronic L-DOPA treatment induced discrete clusters of strongly FosB-like immunoreactive cells within medial and central striatal subregions, as well as in a large, yet sharply defined portion of the lateral caudate-putamen. Strongly labeled cell clusters that appeared in the medial and central caudate-putamen were preferentially located within calbindin-poor, mu-opioid receptor-rich striosomes, whereas the lateral area displaying FosB activation encompassed both striosomal and matrix domains. In both the medial and the lateral striatum a near-total overlap was found between strongly FosB-like immunoreactive cell groups and areas showing pronounced dynorphin expression. NADPH-diaphorase-positive striatal interneurons did not express FosB-like immunoreactivity after a 6-hydroxydopamine lesion alone, a negligible proportion of them did after an acute L-DOPA challenge, but about 8% of these interneurons were FosB positive following chronic L-DOPA treatment. Like FosB, JunB was induced in the DA-denervated striatum by both acute and chronic L-DOPA treatment, and exhibited similar distribution patterns. However, JunB did not exhibit prolonged expression kinetics, and was somewhat down-regulated in the chronically compared with the acutely L-DOPA-treated rats. The present results show that L-DOPA administration produces a long-lasting increase in the levels of FosB-, but not JunB-like immunoreactivity in the dopamine-denervated striatum. More importantly, these data show that striatal induction of FosB- and JunB-like proteins by chronic L-DOPA treatment exhibits both regional and compartmental specificity.

Animals↗
PubMed2000

The connections of the dopaminergic system with the striatum in rats and primates: an analysis with respect to the functional and compartmental organization of the striatum.

This Commentary compares the connections of the dopaminergic system with the striatum in rats and primates with respect to two levels of striatal organization: a tripartite functional (motor, associative and limbic) subdivision and a compartmental (patch/striosome-matrix) subdivision. The topography of other basal ganglia projections to the dopaminergic system with respect to their tripartite functional subdivision is also reviewed. This examination indicates that, in rats and primates, the following observations can be made. (1) The limbic striatum reciprocates its dopaminergic input and in addition innervates most of the dopaminergic neurons projecting to the associative and motor striatum, whereas the motor and associative striatum reciprocate only part of their dopaminergic input. Therefore, the connections of the three striatal subregions with the dopaminergic system are asymmetrical, but the direction of asymmetry differs between the limbic versus the motor and associative striatum. (2) The limbic striatum provides the main striatal input to dopamine cell bodies and proximal dendrites, with some contribution from a subset of neurons in the associative and motor striatum (patch neurons in rats; an unspecified group of neurons in primates), while striatal input to the ventrally extending dopamine dendrites arises mainly from a subset of neurons in the associative and motor striatum (matrix neurons in rats; an unspecified group of neurons in primates). (3) Projections from functionally corresponding subdivisions of the striatum, pallidum and subthalamic nucleus to the dopaminergic system overlap, but the specific targets (dopamine cells, dopamine dendrites, GABA cells) of these projections differ. Major differences include the following. (1) In rats, neurons projecting to the motor and associative striatum reside in distinct regions, while in primates they are arranged in interdigitating clusters. (2) In rats, the terminal fields of projections arising from the motor and associative striatum are largely segregated, while in primates they are not. (3) In rats, patch- and matrix-projecting dopamine cells are organized in spatially, morphologically, histochemically and hodologically distinct ventral and dorsal tiers, while in primates there is no (bi)division of the dopaminergic system that results in two areas which have all the characteristics of the two tiers in rats. Based on the anatomical data and known dopamine cell physiology, we forward an hypothesis regarding the influence of the basal ganglia on dopamine cell activity which captures at least part of the complex interplay taking place within the substantia nigra between projections arising from the different basal ganglia nuclei. Finally, we incorporate the striatal connections with the dopaminergic system into an open-interconnected scheme of basal ganglia-thalamocortical circuitry.

Animals↗
PubMed1998

Selective compartmental dominance: an explanation for a noninfectious, multifactorial etiology for acquired immune deficiency syndrome (AIDS), and a rationale for ozone therapy and other immune modulating therapies.

The most widely accepted etiological explanation for acquired immune deficiency syndrome (AIDS) currently invokes an infectious model involving the human immunodeficiency virus (HIV). Because this infectious model has failed to meet any conventional criteria for establishing microbial causation, this theory still relies on the high, though not perfect, statistical correlation linking presence of HIV antibodies with patients diagnosed with, and at risk for the syndrome. Many scientists and clinicians now doubt the HIV theory, though, and propose instead a multifactorial causation similar to that seen in cancer and heart disease. In order to discard the HIV model, however, it is necessary to explain the high statistical correlation mentioned above. Recent studies involving cellular mediated immunity and cytokine modulation may explain this statistical relationship without the need to invoke infectious causation, by suggesting certain functional characteristics and feedback loops in the immune system which the author calls selective compartmental dominance (SCD). SCD provides a model in which chronic dominance of the humoral immune compartment secondary to chronic high-dose antigenic challenge results in chronic suppression of the cellular immune compartment. This model predicts that even HIV-negative members of the risk groups are susceptible to AIDS, assigns no special causal role for HIV in AIDS, and suggests a rational course of nontoxic therapy that can potentially reverse cases in the earlier stages.

Acquired Immunodeficiency Syndrome↗
PubMed1999

A compartmental absorption and transit model for estimating oral drug absorption.

This report describes a compartmental absorption and transit model to estimate the fraction of dose absorbed and the rate of drug absorption for passively transported drugs in immediate release products. The model considers simultaneous small intestinal transit flow and drug absorption. Both analytical and numerical methods were utilized to solve the model equations. It was found that the fraction of dose absorbed can be estimated by F(a) = 1-(1+0.54 P(eff))(-7), where P(eff) is the human effective permeability in cm/h. A good correlation was found between the fraction of dose absorbed and the effective permeability for ten drugs covering a wide range of absorption characteristics. The model was able to explain the oral plasma concentration profiles of atenolol.

Adsorption↗
PubMed1996

Eph receptors and ligands comprise two major specificity subclasses and are reciprocally compartmentalized during embryogenesis.

We report that the many Eph-related receptor tyrosine kinases, and their numerous membrane-bound ligands, can each be grouped into only two major specificity subclasses. Receptors in a given subclass bind most members of a corresponding ligand subclass. The physiological relevance of these groupings is suggested by viewing the collective distributions of all members of a subclass. These composite distributions, in contrast with less informative patterns seen with individual members of the family, reveal that the developing embryo is subdivided into domains defined by reciprocal and apparently mutually exclusive expression of a receptor subclass and its corresponding ligands. Receptors seem to encounter their ligands only at the interface between these domains. This reciprocal compartmentalization implicates the Eph family in the formation of spatial boundaries that may help to organize the developing body plan.

Animals↗
PubMed2002

Compartmentalized Eph receptor and ephrin expression in the thymus.

The maturation of T cells is an intricate process involving the interaction of developing thymocytes with discrete microenvironments within the thymus. Numerous studies have indicated that distinct thymic compartments provide signals required for each stage of thymocyte maturation. In this study we performed a comprehensive analysis of the expression patterns of Eph-A receptors and ephrins-A in the thymus using in situ hybridization and reverse transcription-polymerase chain reaction, and show that expression of these molecules is highly compartmentalized. Based on these expression patterns and the known mechanisms of action of Eph receptor/ephrin interactions in other organs, these data suggest that differential Eph receptor expression on discrete subsets of thymic stromal cells may be important in establishing compartment boundaries and preventing intermingling of stromal cell subtypes. Further, together with chemotactic signals such as those provided by chemokines, regulated Eph receptor/ephrin expression on thymocytes may play a role in thymocyte migration.

Cell Differentiation↗
PubMed1997

Applications of abduction: hypothesis testing of neuroendocrinological qualitative compartmental models.

It is difficult to assess hypothetical models in poorly measured domains such as neuroendocrinology. Without a large library of observations to constrain inference, the execution of such incomplete models implies making assumptions. Mutually exclusive assumptions must be kept in separate worlds. We define a general abductive multiple-worlds engine that assesses such models by (i) generating the worlds and (ii) tests if these worlds contain known behaviour. World generation is constrained via the use of relevant envisionment. We describe QCM, a modeling language for compartmental models that can be processed by this inference engine. This tool has been used to find faults in theories published in international refereed journals; i.e. QCM can detect faults which are invisible to other methods. The generality and computational limits of this approach are discussed. In short, this approach is applicable to any representation that can be compiled into an and-or graph, provided the graphs are not too big or too intricate (fanout < 7).

Computer Simulation↗
PubMed1998

Compartmentalization of pro-inflammatory cytokines in tuberculous pleurisy.

Increased levels of interleukin-6 (IL-6) and IL-8 are found in various immunologically mediated inflammatory disorders. Concentrations of IL-6, IL-8 and the soluble form of the IL-6 receptor (sIL-6R) were determined in serum and effusion fluid of 25 patients with tuberculous pleurisy utilizing enzyme linked immunosorbent assays (EIA). Serum IL-6 levels were only slightly increased in patients with tuberculous pleurisy in comparison to controls (11.1 +/- 2.1 vs 7.3 +/- 1.0 pg ml-1). IL-8 could not be detected in the serum of tuberculosis patients, but it was detected in the serum of healthy controls (8.0 +/- 1.5 pg ml-1). In comparison to serum, IL-6 and IL-8 were found in high concentrations in pleural effusions (IL-6: 932 +/- 70 vs 11.1 +/- 2.1 pg ml-1, P < 0.0001; IL-8: 450 +/- 85 vs 0 +/- 0 pg ml-1). In contrast, sIL-6R concentrations were much higher in serum compared to pleural effusion levels [30,477 +/- 1905 vs 9881 +/- 1177 pg ml-1, P < 0.0001 (mean +/- SEM)]. The authors conclude that elevated levels of IL-6 and IL-8 in pleural effusions are compartmentalized at the site of active disease. The low levels of sIL-6R in the presence of high levels of IL-6 in pleural effusions, and the high levels of sIL-6R in the presence of low levels of IL-6 in serum suggest that the expression or shedding of sIL-6R may be downregulated in the presence of excessive amounts of IL-6.

Adult↗
PubMed2001

Gender related differences in the effect of aging on blood amino acid compartmentation*

This work has been focused on the study of the variations in blood amino acid compartmentation (plasma and blood cells) with aging, both in men and women. Aging is a situation which, under the influence of gender, involves a decline in body weight functions and variations in energy metabolism with a deterioration of muscular metabolism leading to changes in amino acid handling. We determined the blood levels of individual amino acids in whole blood, plasma compartment and blood cell compartment of 51 men and 51 women. Subjects were classified in three age groups-AG1 (18 to 35 y), AG2 (35-50 y) and AG3 (more than 50 y). Aging was accompanied by significant changes in blood levels of amino acids showing gender-linked differences which were distinct for both blood compartments (plasma and blood cells). In men, aging was accompanied by a drop in blood levels of several amino acids, due mainly to the plasma compartment, whereas in women aging brought about a rise in blood levels of various amino acids mainly in blood cell compartment. This paper contributes to enhancing the physiological importance of the blood cell pool in the handling of amino acids.

Journal Article↗