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PubMed1986

Effect of starvation and protein-feeding on blood amino acid compartmentation of domestic fowl hatchlings.

The amino acid concentrations in plasma and blood cells of 5-day old domestic fowl hatchlings that received either standard feeding, protein-feeding or were starved have been determined. The effects of 5-day starvation or protein feeding did not alter significantly the combined amino acid concentration of blood plasma, but decreased blood cell levels. The patterns of individual amino acid changes observed in starvation or protein-feeding were similar in both groups when compared with those of controls. However, starvation-induced effects were actually more marked than those observed in protein-fed animals. The patterns of change with starvation of individual amino acids in the hatchling blood compartments were very different from those observed in mammals subjected to short or medium-term starvation. The mechanisms controlling circulating amino acid concentrations act in both situations studied to maintain the plasma amino acid concentrations despite marked changes in the availability of 2-amino nitrogen energy to the animal; changes in blood amino acid compartmentation buffering plasma amino acid availability.

Amino Acids↗
PubMed1986

Conductivity-mediated regulation in a compartmental enzyme system. Superactivation and conductance bistability.

This paper deals with the 'conductivity effect' which results from the action of an electric current in a compartmental system involving a chemical reaction producing ionic species. This effect, due to the difference between internal and external conductivities, leads to the accumulation of ionic species inside the reactive compartment. Different results are obtained depending on the considered kinetics: amplification of reaction rate increase, and chemical and conductance bistabilities.

Biological Transport↗
PubMed1981

Evidence for compartmentalization of glutamate in rat brain synaptosomes using the glutamate sensitivity of phosphate-activated glutaminase as a functional test.

The glutamate content of rat brain synaptosomes was measured by high performance liquid chromatography to be 39 micromol/g protein. If uncompartmentalized this glutamate (4 mM) would inhibit phosphate-activated glutaminase considerably. Since the action of any endogenous effector on the enzyme is assumed to be negligible following disruption of the synaptosomes, due to dilution with the incubation medium, the inhibition by glumate and activation by phosphate were compared in intact and disrupted synaptosomes. The inhibition by endogenous glutamate in intact synaptosomes was found to correspond to less than that of 0.5 mM of added glutamate to disrupted synaptosomes, indicating that the major fraction of synaptosomal glutamate is compartmentalized.

Animals↗
PubMed1995

Glutamate and glutamine metabolism in cultured GABAergic neurons studied by 13C NMR spectroscopy may indicate compartmentation and mitochondrial heterogeneity.

Primary cultures of mouse cerebral cortical neurons were incubated for 3 h with 250 microM [U-13C]glutamate or 250 microM [U-13C]glutamine and 6 mM glucose. 13C NMR spectra of cell extracts exhibited distinct multiplets for glutamate, aspartate and GABA. Incorporation of label into aspartate can only occur through the tricarboxylic acid (TCA) cycle, but as demonstrated by formation of the 3,4-13C2-isotopomer of GABA and the 1,2,3-13C3-isotopomer of glutamate, these amino acids were also to some extent derived from this pathway. Formation of the 1,2-13C2-(1J1,2 = 50 Hz) and 3,4-13C2-isotopomer (1J3,4 = 50.9 Hz) in aspartate occurs exclusively when oxaloacetate (containing 12C) is derived from the second turn of the TCA cycle. From [U-13C]glutamine, the 12C containing isotopomers in aspartate accounted for 27% of the total label and from [U-13C]glutamate, it was less than 10%. When [U-13C]glutamine was the precursor, 36% of the labeled glutamate and 52% of the labeled GABA contained 12C incorporated during the first turn of the TCA cycle. These numbers decreased to 15 and 30%, respectively when [U-13C]glutamate was used. Since glutamine must be converted to glutamate before it can enter the TCA cycle as 2-oxoglutarate, appearance of 12C incorporation in aspartate should be identical when [U-13C]glutamate and [U-13C]glutamine was used as substrates. This was, however, not observed which may be indicative of (1) compartmentation of mitochondrial glutamate metabolism or (2) differences in the amount of intramitochondrial glutamate derived from external glutamate or glutamine.

Animals↗
PubMed1995

Compartmental organization of calretinin in the rat striatum.

The present study examined the compartmental distribution of a calcium-binding protein, calretinin, in the rat striatum. Calretinin-immunoreactive cells were homogeneously scattered throughout the striatum, but calretinin-immunoreactive fibers were clustered as patches in the medial, central and ventral caudoputamen and in the lateral nucleus accumbens. These patches corresponded to striosomes, identified by immunostaining for calbindin-D28 K in adjacent sections. In the medial nucleus accumbens, calretinin-immunoreactive fibers showed diffuse distribution with occasional islands of calretinin-poor zones. These islands contained tightly packed, Nissl-stained cells, which have been previously shown to correspond to mu-opiate receptor-rich patches. Calretinin-positive fibers fill striosomes/patches in the caudoputamen and in the lateral nucleus accumbens and avoid them in the medial nucleus accumbens.

Animals↗
PubMed1992

Metabolic compartmentation of glutamate and glutamine: morphological evidence obtained by quantitative immunocytochemistry in rat cerebellum.

An electron microscopic, double-labelling immunocytochemical procedure was used to assess the level of fixed glutamate and glutamine in different cell profiles in ultrathin sections of rat cerebellar cortex. The procedure was based on sequential immunolabelling with two rabbit antisera, using gold particles of different sizes as markers and formaldehyde vapour as a means to avoid interference between the two incubations. Model sections containing a series of known concentrations of the respective amino acids (aldehyde--fixed to rat brain protein) were incubated together with the tissue material. These revealed a close to linear relationship between gold particle density and antigen concentration throughout the range of biological relevance. The ratio between the density of the two categories of gold particles was calculated for the individual profile types. This ratio showed a 20-fold variation, with the highest glutamate/glutamine ratios obtained for putative excitatory terminals (terminals of parallel fibres in the outer part of the molecular layer, followed by mossy and climbing fibre boutons) and the lowest for glial cells (Bergmann glia, astrocytes in the granule cell layer, and oligodendrocytes). Granule cell bodies and dendrites, and cell bodies and processes of putative GABAergic cells (Purkinje, basket and Golgi cells) displayed intermediate ratios. The ratios corresponded to millimolar ratios (mM fixed glutamate/mM fixed glutamine) ranging from 4.5 to 0.2, tentatively assessed by adjusting for differences in labelling efficiency of the two antigens. Our results show that the compartmentation of glutamate and glutamine, an issue previously addressed mainly in the test tube, can be studied in morphologically intact preparations at a resolution that matches the complexity of CNS tissue. The data indicate that glutamate is effectively converted to glutamine in all categories of glial cells, and that glutamate synthesis prevails in each of the three types of excitatory terminals in the cerebellar cortex. Terminals of putative GABAergic cells form a distinct low glutamate/low glutamine compartment.

Animals↗
PubMed1993

Compartmental loss of NADPH diaphorase in the neuropil of the human striatum in Huntington's disease.

The distribution of NADPH diaphorase staining in the human basal ganglia was compared in five cases who were neurologically normal with five cases who died with Huntington's disease. The normal cases showed an intense staining for NADPH diaphorase throughout all regions of the neuropil in the striatum (caudate nucleus, putamen and nucleus accumbens); the staining in the neuropil was largely homogeneous although a heterogeneous distribution was evident at rostral levels of the head of the caudate nucleus and in the nucleus accumbens where patches of reduced staining aligned with acetylcholinesterase-poor regions. The globus pallidus showed a moderately intense homogeneous pattern of staining for NADPH diaphorase. In comparison with control cases, sections of the striatum from the five cases with Huntington's disease showed a dramatic decrease in the intensity of NADPH diaphorase staining in the neuropil, especially in the caudate nucleus and putamen. In cases of early Huntington's disease where no discernible loss of neurons was seen [grade 0 using the grading criteria of Vonsatell et al. (1985) J. Neuropath. exp. Neurol. 44, 559-577], there was a marked heterogeneous pattern of staining in the caudate nucleus and putamen showing a patchy loss of NADPH diaphorase in the neuropil. This resulted in clearly delineated islands of greatly reduced staining surrounded by a matrix of moderately reduced staining; the patches of greatly reduced staining corresponded with acetylcholinesterase-poor striosomes. In cases of more advanced neuropathology (grades 1 and 2) the loss of NADPH diaphorase staining in the neuropil was even more marked, affecting both acetylcholinesterase-poor and acetylcholinesterase-rich regions of the caudate nucleus and putamen and resulting in an almost homogeneous loss of staining in these striatal regions. Despite this marked loss of staining in the neuropil, the numbers of NADPH diaphorase-stained neuronal somata in the striatum in Huntington's cases appeared comparable to those in the control cases. In the globus pallidus of one of the advanced Huntington's disease cases there appeared to be a minimal loss of NADPH diaphorase staining; however, staining in the other regions of the brain which were examined was similar to that in the control cases. These findings demonstrate a progressive compartmental loss of NADPH diaphorase in the neuropil of the human striatum in Huntington's disease which correlates with the extent of neurodegeneration; early in the disease the loss of neuropil staining is first evident in the striosome compartment, then followed by an additional loss in the matrix compartment in more advanced cases of the disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1993

Signal transmission in lobster olfactory receptor cells: functional significance of electrotonic structure analysed by a compartmental model.

The electrotonic structure of lobster olfactory receptor cells was evaluated using general purpose simulation software in a compartmental model derived from electron-microscopic reconstruction. The model with non-uniform membrane resistance (Rm) was used to (i) simulate current spread and (ii) determine if the electronic structure of the cell improves signal recognition in the soma. The odor-evoked conductance change in dendrites was calculated according to the Michaelis-Menten equation with the assumption that the outer dendritic segments function as independent stimulus detectors. The inflection point of the concentration-response function measured in the soma was shifted to lower concentrations relative to that measured in the ciliary (outer dendritic) arbor. The shift, which was greater for inputs with lower efficacy (represented in the model by smaller Hill coefficients) and for the dynamic phase of the response than for the steady-state phase, effectively increased the selectivity of the somatic response. Randomized input distributed uniformly to progressively more restricted areas of the ciliary arbor showed that stimulation of larger areas (presumably the entire ciliary arbor) decreased the statistical variability of the somatic response.

Animals↗
PubMed1993

Ontogeny of the proenkephalin system in the rat corpus striatum: its relationship to dopaminergic innervation and transient compartmental expression.

The earliest detection of the proenkephalin gene was on embryonic day 16 in neuronal cell bodies in the ventrolateral portion of the caudal neostriatum. This expression was identified by both immunocytochemistry for synenkephalin, the nonopioid N-terminus of proenkephalin (1-70), and preproenkephalin in situ hybridization with a complementary DNA probe. Two developmental gradients of preproenkephalin expression and synenkephalin immunoreactivity were observed: (i) a ventrolateral to dorsomedial and caudal to rostral gradient in the rostral caudate-putamen; and (ii) a ventromedial to dorsolateral and rostral to caudal gradient in the caudal caudate-putamen. Ventrolateral to dorsomedial and caudal to rostral developmental gradients of synenkephalin fiber immunoreactivity were also identified in the globus pallidus. Methionine enkephalin immunoreactivity was not consistently detectable until postnatal day 10 and 15 in the rostral and caudal globus pallidus, respectively. A transient patchy distribution of increased preproenkephalin expression from embryonic day 20 through postnatal day 5 occurred. These patches and a subcallosal streak were found to overlap partially with areas of increased tyrosine hydroxylase immunoreactivity by adjacent section analyses. The earliest detection of tyrosine hydroxylase immunoreactivity was found to coincide with that of proenkephalin on embryonic day 16, but in differing regions of the corpus striatum. Tyrosine hydroxylase immunoreactivity in the rostral caudate-putamen preceded, while in the caudal caudate-putamen it followed first expression of the proenkephalin gene. Early proenkephalin expression, by both synenkephalin immunocytochemistry and preproenkephalin in situ hybridization, was also detected in the central nucleus of the amygdala on embryonic day 16 immediately ventral to the area of expression in the caudate-putamen. Preproenkephalin expression in the olfactory tubercle and nucleus accumbens first appeared on embryonic day 20 and expression proceeded in a lateral to dorsomedial gradient continuous with the ventral part of the rostral caudal-putamen. Relatively late detection of methionine enkephalin immunoreactivity in comparison to synenkephalin possibly indicates a developmental delay in the complete enzymatic processing of the proenkephalin precursor. Differing gradients in the ontogeny of preproenkephalin expression in the rostral vs the caudal caudate-putamen suggest possible anatomical and developmental differences of these two regions. Also, transient compartmentalization of preproenkephalin expression and differences in dopaminergic innervation as detected by tyrosine hydroxylase immunoreactivity were further support for the existence of two subsets of proenkephalinergic neurons in the caudate-putamen. Contemporaneous development of preproenkephalin expression and synenkephalin immunoreactivity in the central nucleus of the amygdala with the ventral part of the caudal caudate-putamen also suggested developmental homology.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1995

The human neostriatum shows compartmentalization of neuropeptide gene expression in dorsal and ventral regions: an in situ hybridization histochemical analysis.

Expression of neuropeptide messenger RNAs in striatal neurons was studied in post mortem human brain tissue by the use of in situ hybridization histochemistry. Clusters of cells expressing high levels of prodynorphin messenger RNA, and less strikingly, preprotachykinin messenger RNA, were prominent in the caudate nucleus and were present but less pronounced in the putamen. Proenkephalin and prosomatostatin messenger RNA-containing cells were more homogeneously distributed throughout the striatum, though the latter were much sparser. The four neuropeptide messenger RNA patterns in the nucleus accumbens were rather homogeneous compared with the dorsal striatum. Of these, prodynorphin messenger RNA showed a higher level of expression per cell in the nucleus accumbens relative to the dorsal striatum. The relationship of neuropeptide-containing cell clusters to the striosomal organization was characterized by looking at the register of these markers with patterns of low acetylcholinesterase activity and dense mu opiate receptor binding. In the caudate and putamen, clusters of cells expressing high levels of dynorphin and preprotachykinin messenger RNAs were clearly in register with the striosomes. The accumbens was defined by high prodynorphin messenger RNA levels, both low and high levels of acetylcholinesterase staining, and very low to absent mu opiate receptor binding. The distribution of high-expressing prodynorphin messenger RNA-containing cells--to the patch compartment and throughout the entire ventral striatum/nucleus accumbens region--defines the limbic domain of the neostriatum and suggests particular relevance to human striatal organization and function, because the distribution of this opioid neuropeptide is considerably more compartmentalized in human than in non-human species.

Acetylcholinesterase↗
PubMed1989

Superiority of perfusion over bolus administration in cancer chemotherapy: proposition of a compartmental model.

Recent studies indicate that, for cancer chemotherapy, prolongation of drug injection time yields lower toxicity and better efficacy. We propose a compartmental pharmacological model to explain these observations. The model has been simulated on an analog computer. The curves obtained give a credible explanation for the clinical data. The superiority of perfusion over bolus injection may be attributed to plasma peak suppression.

Antineoplastic Agents↗
PubMed1992

Compartmental syndrome in Duchenne muscular dystrophy: early evaluation of an epiphenomenon leading to wasting, weakness and contracture.

Elevation of intracompartmental calf pressure in Duchenne Muscular Dystrophy can cause compartmental syndrome which accelerates mechanical muscle damage. Relief of increased pressure by fasciotomy inhibits this process. Intermittent pressure monitoring may prove of value in the routine orthopaedic management of patients with this disease. A historically controlled study to determine long term clinical benefit is in progress.

Child↗
PubMed1986

1H-NMR relaxation times and water compartmentalization in experimental tumor models.

The present studies were conducted with RIF-1, M5076 and Panc02 subcutaneous tumor models to assess the relationship between tissue-free water compartmentalization and observed tissue T1 and T2 changes at 10 MHz. Observed T1 was shown to correlate directly with total extracellular water and interstitial water volumes. T1 and T2 were also inversely related to intracellular water volumes. T1 and T2 decreases after dexamethasone treatment were, however, most closely correlated with changes in tumor extracellular water and not changes in cell or total water volumes. Studies to assess Gd-DTPA-dimeg dose dependent T1 and T2 modification in model serum protein solutions indicated that although the Gd concentration that reduced T2 by 50% was about 2.5 fold greater than that required to reduce T1 equally, the of the concentration dependent T1 and T2 modifications were similar. In studies with tumor models, the injected dose of Gd-DTPA-dimeg that reduced T1 by 50% was inversely correlated with tumor extracellular water volumes. The slopes for dose dependent T1 modification in all tumors were similar and similar to that observed for model protein solutions. Gd-DTPA-dimeg had a different effect on observed T2 values for the 3 tumor models. Exponential slopes were about twice that observed for T2 modification of serum protein solutions, and Gd-DTPA-dimeg doses that reduced observed tumor T2 ranged from 9 to 50 times that necessary to similarly reduce T1. The results from these studies indicate that the observed T1, for these tumors, was dominated by relaxation of water protons in interstitial water but that the observed T2 was most strongly influenced by proton relaxation in water compartments that were unavailable to the Gd labeled probe.

Animals↗
PubMed1988

Calcium compartmentation in isolated renal tubules in suspension.

Substantial increases of total cell Ca2+ have been observed in suspensions of isolated rabbit proximal tubules subjected to hypoxic injury or treated with exogenous ATP followed by apparent recovery with reoxygenation of the hypoxic tubules or continued incubation of ATP-treated tubules. Ca2+ compartmentation studies using digitonin and metabolic inhibitors were done to clarify the basis for these changes. Digitonin, 40-90 micrograms/mg tubule protein, rapidly permeabilized the tubule cells and did not impair mitochondrial Ca2+ sequestration. Most of the increases of tubule cell Ca2+ produced by hypoxia and ATP were accounted for by pools which could be rapidly removed by exposure of tubules to EGTA and the uncoupler carbonyl cyanide m-chlorophenyl hydrazone without concomitant use of digitonin, suggesting that the changes of Ca2+ predominantly reflect sequestration by mitochondria in severely damaged cells or mitochondria already released to the medium from them. The time course of uptake followed by spontaneous release of mitochondrial Ca2+ from tubule cells deliberately permeabilized with digitonin, then incubated for prolonged periods, indicated that the decreases of tubule cell Ca2+ during reoxygenation of hypoxic suspensions and prolonged incubation of ATP-treated tubules were likely to be attributable to loss of Ca2+ from free mitochondria and those in damaged cells rather than to extrusion by intact cells.

Adenosine Triphosphate↗
PubMed1993

Compartmentalization of acetylcholinesterase mRNA and enzyme at the vertebrate neuromuscular junction.

Acetylcholinesterase (AChE) is concentrated at the vertebrate neuromuscular synapse. To determine whether increased transcript levels could underlie this selective accumulation, we employed a quantitative reverse transcription polymerase chain reaction-based assay to determine mRNA copy number in samples as small as single neuromuscular junctions (NMJs) and a microassay to measure AChE enzyme activity at single synapses. Our results show that AChE mRNA is an intermediate transcript at NMJs, whereas in noninnervated regions of muscle fibers, AChE transcripts are either undetectable or rare. In contrast, alpha-actin transcript levels in the same samples are similar in junctional and extrajunctional regions. However, compared with AChE enzyme activity and alpha-actin mRNA levels, the levels of AChE transcripts at NMJs are highly variable. These results indicate that AChE mRNA and protein expression are compartmentalized at the vertebrate NMJ and provide a direct approach toward dissecting the molecular events leading from synaptic activation to plastic changes in gene expression at single vertebrate synapses.

Acetylcholinesterase↗
PubMed1993

Influence of fatty acid backdiffusion on compartmental analysis of external detection curves obtained with 123-iodohexadecenoic acid in isolated rat heart.

In isolated rat hearts, we investigated a possible backdiffusion of fatty acids and tried to determine whether it impaired our compartmental analysis of myocardial time-radioactivity curves obtained with an iodinated fatty acid, 16-iodo-9-hexadecenoic acid (IHA). Backdiffusion was not observed directly in the coronary effluents but was estimated by analysis of the external detection curves. Furthermore, when backdiffusion was not taken into account in the mathematical analysis, we obtained similar data on IHA intramyocardial metabolism.

Albumins↗
PubMed1993

Compartmental analysis of the pharmacokinetics of radioiodinated monoclonal antibody B72.3 in colon cancer patients.

Sixteen patients with colorectal cancer were administered 37-74 MBq (1 mg) of radioiodinated B72.3 monoclonal antibody. Pharmacokinetic analysis was carried out on plasma and urine samples. Elimination from the plasma was biexponential with a mean T1/2 alpha of 3.7 h and T1/2 beta of 62.4 h. The plasma clearance was fit to a two-compartmental model. This was combined with a previously reported model for radioiodine to construct a composite model. There was a good correlation (r = 0.952) between the model-predicted and observed excretion of radioiodine suggesting that the composite model is compatible with the pharmacokinetics of the radiolabelled antibody.

Adult↗
PubMed2005

Divergent folding pathways of two homologous proteins, BPTI and tick anticoagulant peptide: compartmentalization of folding intermediates and identification of kinetic traps.

Bovine pancreatic trypsin inhibitor (BPTI) and tick anticoagulant peptide (TAP) are two structurally homologous proteins, which have been shown to exhibit distinct mechanisms of oxidative folding. We demonstrate here differences of their folding properties using the technique of disulfide scrambling. Two extensively unfolded homologous isomers (beads-form) of BPTI (Cys5-Cys14, Cys30-Cys38, Cys51-Cys55) and TAP (Cys5-Cys15, Cys33-Cys39, Cys55-Cys59) were allowed to refold in parallel via disulfide shuffling of 13 potential isomers to form the native structure. Folding intermediates were trapped by acid quenching and analyzed by HPLC. The results reveal the following diversities: (a) there are two predominant folding intermediates of BPTI and seven well-populated folding intermediates of TAP. One of the two predominant BPTI intermediates (Cys5-Cys14, Cys30-Cys51, Cys38-Cys55) contains a native disulfide Cys30-Cys51 and constitutes about 34% of the total BPTI folding intermediates. In contrast, the TAP counterpart (Cys5-Cys15, Cys33-Cys55, Cys39-Cys59) represents only 5% of the total TAP intermediates; (b) three isomers of TAP sharing a stable non-native disulfide bond Cys15-Cys33 are shown to act as kinetic traps of TAP folding. Their counterparts are conspicuously absent in the BPTI folding; and (c) most significantly, folding intermediates of BPTI are found to be energetically compartmentalized, whereas most folding intermediates of TAP are inter-convertible and exist in dynamic equilibrium. Our studies further demonstrate optimal concentrations of denaturant required for destabilization of kinetic traps and acceleration of TAP folding.

Animals↗