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PubMed1990

Compartmentalization of mammalian proteins produced in Escherichia coli.

We have examined the patterns of compartmentalization of several mammalian proteins in Escherichia coli which do not have signal peptides or functional signal peptide equivalents. These proteins include (i) human proapolipoprotein A-I (proapoA-I), a 249-residue protein which contains a hexapeptide NH2-terminal prosegment plus a mature domain of 243 residues comprised of tandemly arrayed, docosapeptide repeats with predicted amphipathic alpha-helical structure; (ii) the mature apoA-I molecule without its prosegment; (iii) mouse interleukin-1 beta (IL-1 beta), a 17-kDa protein which is composed of 12 beta strands that form a tetrahedral structure; and (iv) the 31-kDa precursor of IL-1 beta, proIL-1 beta. Efficient expression of these proteins in E. coli was achieved using a plasmid that contains the nalidixic acid-inducible recA promoter and ribosome binding site from the gene 10 leader of bacteriophage T7. In induced cultures the mammalian proteins represented up to 20% of the total bacterial protein mass. Surprisingly, cell fractionation using cold (osmotic) shock indicated that proapoA-I, apoA-I, and IL-1 beta, but not its 31-kDa precursor, were segregated into the periplasmic space with high efficiency: the ratio of periplasmic space/spheroplast distribution ranged from 0.6 to 1.1 in cells harvested 60-180 min after nalidixic acid induction. Not only was this compartmentalization efficient but it was also selective: analysis of the osmotic shock fractions revealed that the periplasmic space preparations were not contaminated with cytoplasmic proteins (e.g. phosphoglycerate dehydrogenase). Sequential Edman degradation showed that these proteins had not undergone any NH2-terminal proteolytic processing. The mammalian proteins did not affect the export of a prototypic bacterial preprotein, beta-lactamase. Together the data suggest that osmotic shock fractionation of E. coli may facilitate the purification of functional foreign proteins produced in this prokaryote. They also raise the possibility that structural elements in these proteins other than conventional signal peptides may effect periplasmic targeting in E. coli.

Amino Acid Sequence↗
PubMed1990

Lower extremity compartmental syndrome following snake-bite envenomation--one case report.

Acute compartmental syndrome develops when the intracompartmental pressure rises rapidly, even if only for a short duration. Loss of function and/or viability of the intracompartmental muscles may occur within a short period. Consequently early recognition and management are essential. We report a case where a young child with severe snake bite envenomation who and acute compartmental syndrome who had complete functional recovery following emergent fasciotomy and delayed primary closure.

Compartment Syndromes↗
PubMed1987

Ontogeny, compartmentation, and turnover of spectrin isoforms in rat central neurons.

A variant of a principal structural protein of erythrocytes, spectrin, is a major neuronal protein. Here we have examined the subcellular and regional distributions, subunit composition, ontogeny, and metabolism of spectrin in rat CNS. While all subcellular fractions, except the mitochondrial, expressed the previously characterized brain form of spectrin (fodrin, or alpha gamma-spectrin), limited brain regions contained, in cytoplasm, a second isoform immunologically related to erythrocyte alpha beta-spectrin. Both alpha gamma- and alpha beta-spectrin are primarily neuronal, as evidenced by immunocytochemistry. The spectrins are distributed between 2 distinct subneuronal compartments: a membrane-associated domain containing alpha gamma-spectrin in relatively constant amounts across brain regions, and a cytoplasmic domain containing both the alpha gamma and alpha beta isoforms in widely varying amounts across brain regions. Although forebrain has considerable alpha beta-spectrin, the diencephalon, mesencephalon, and brain stem are devoid of this isoform. Further evidence for spectrin compartmentation comes from its ontogeny. Membrane-associated alpha gamma-spectrin is present at birth at its adult levels, but cytoplasmic alpha beta-spectrin is expressed only following the second postnatal week. Similarly, the 4-fold difference in cytoplasmic alpha gamma-spectrin content across brain regions develops during the third postnatal week. In this compartment, both spectrin forms may be metabolized in vivo, at least in part, by calcium-activated proteolysis. The presence in mammalian neurons of 2 spectrin isoforms and their compartmentation into distinct domains suggests multiple functions for neuronal spectrin, one of which may be in the stabilization or maturation of forebrain neurons.

Aging↗
PubMed1987

Blood amino acid compartmentation in mice bearing Lewis lung carcinoma.

Blood amino acid compartmentation between plasma and red blood cells was studied in mice bearing the Lewis lung carcinoma. The animals showed a change in compartmentation with an increase in the concentration of most amino acids in the plasmatic fraction with the exception of glycine, glutamine, aspartate, asparagine, and taurine. This work focuses on the importance of studying the distribution of amino acids in both fractions when performing studies concerning amino acid metabolism in tumor-bearing animals.

Amino Acids↗
PubMed1985

Compartmental analysis: theoretical aspects and application.

The basic equations governing the kinetics of metabolic compartmental systems are presented. The most difficult problem in compartmental analysis is the so-called inverse problem which is the estimation of model parameters from experimental data. Two examples are considered how to tackle this problem. The first example concerns the distribution of isotopic carbon atoms in the citric acid cycle. Starting from a matrix formulation of the problem the major steps are outlined towards an analytical solution for this rather complex system. An application of the theoretical approach to the citric acid cycle of rabbit reticulocytes is given. The second problem deals with the kinetic characterization of biochemical reactions proceeding at the same time in different physiological spaces with different rates. Such a situation is, for example, the infection of red blood cells by malaria parasites. Both the host cell and the parasite possess the complete glycolytic pathway. A theoretical approach is proposed to estimate the flux rates through this pathway separately for each of the two spaces when only the total rates and metabolite concentrations are available as experimental data.

Animals↗
PubMed1982

The compartmental syndrome: a serious complication of acute rhabdomyolysis.

The compartmental syndrome is not a rare complication of non-traumatic rhabdomyolysis. Early recognition and prompt surgical decompression of the affected area are essential. We feel that a lack of familiarity with the syndrome among nephrologists may contribute to delay in diagnosis and treatment and reduce the chances for functional neuromuscular recovery. Our experience with three cases following overdosage of alcohol (case 1), barbiturates (case 2) and a mixture of alcohol and sedatives (case 3) is reported. The pathogenesis, symptomatology and treatment of the compartmental syndrome in this setting are discussed.

Adult↗
PubMed1982

Compartmentalization of phosphatidylethanolamine in microsomal membranes from rat liver.

Microsomal membranes from rat liver were treated with the cross-linking reagent 1,5-difluoro-2,4-dinitrobenzene (DFDNB). Experimental work showed that at a probe concentration of 0.75 mM all free phosphatidylethanolamine (PE) and phosphatidylserine (PS) were found as dinitrophenyl derivatives: 29% of PE was in monomeric form, 9% dimeric, 2% interacted with PS, and 63% cross-linked to protein. PS showed a greater percent in monomeric and dimeric form and only 31% was cross-linked to protein. The cross-linking pattern of PE was clearly different from that pattern which is present in the inner mitochondrial and erythrocyte membranes. In vivo labeling of PE with [(3)H]glycerol and [(3)H]ethanolamine followed by phospholipase A(2) treatment of isolated microsomes established a heterogeneous labeling pattern during the first 2 hours. During this period, the specific activity of the phospholipase A(2)-sensitive compartment was considerably higher. The differential distribution of radioactivity after in vivo labeling in the part of the PE which reacted with increasing concentrations of DFDNB also indicated compartmentalization. After in vivo labeling with the precursors, the time course of the specific radioactivity demonstrated an initial high labeling, almost exclusively in the monomeric form, followed by a later appearance of the label in the protein-bound PE. The experiments indicate that the biosynthesis of PE takes place in a compartment that is more accessible to surface probes and that the labeled molecules are transferred in a time-dependent process to a second compartment where the lipid is not available for phospholipase A(2) action but is available for cross-linking to protein.-Valtersson, C., and G. Dallner. Compartmentalization of phosphatidylethanolamine in microsomal membranes from rat liver.

Animals↗
PubMed1981

Compartmental pressure measurements: an experimental investigation using the slit catheter.

A new catheter employing a different technique to monitor compartmental pressure has been developed. The accuracy of the catheter was compared to a wick catheter and to the needle manometer technique for monitoring compartmental pressure. The slit catheter is the most accurate of the three techniques for continuous pressure monitoring for periods of up to 24 hours in the experimental canine model. The slit catheter is as accurate as the wick catheter for pressure measurements from 0 through 10 mm Hg. The needle technique has proven to be the least accurate of the three.

Animals↗
PubMed1981

Biochemical compartmentation of fish tissues. Cholesterol in the brain and spinal cord.

The differential distribution of cholesterol in different regions of the brain in 9 nutritionally important fishes were compartmentalized biochemically. The cholesterol content which was higher in the spinal cord than in the 4 brain regions, varied individually and groupwise; the medulla oblongata and cerebrum contained the highest and lowest amounts, respectively. The piscivorous fishes contain more cholesterol than cat fishes and major carps. A direct relationship was observed between the course of evolution and the cholesterol content in different regions of the brain and spinal cord of the nine kinds of fish studied. The differential distribution of cholesterol content in various regions of the brain and spinal cord are discussed in relation to phylogeny, diet and activity of the fish. Phylogeny seems to influence the biochemical compartmentation of the fish brain in relation to its cholesterol content.

Animals↗
PubMed1980

Pharmacokinetics in nonlinear and partially compartmentalized systems.

The pharmacokinetics of complex systems both linear and nonlinear, compartmentalized, distributed, and partially compartmentalized are reviewed. The two problems considered are: 1) the prediction of concentration or pharmacological effects, and 2) the determination of the input (absorption, dosage schedule) from a given set of measured or desired concentrations. These problems are solved using the super-position integral in linear time-invariant systems by i) integration and ii) deconvolution respectively. Time-varying systems are dealt with by using tracer methods. Nonlinear systems are defined as systems with concentration-dependent parameters. The examples of Michaelis-Menten kinetics, tissue binding, and threshold effects are considered. Approaches to solutions of these problems are generally model-dependent and achieved through i) system identification (parameter estimation), ii) linearization for limiting cases, and iii) tracer techniques. Tracer techniques effectively linearize a nonlinear system so that some variable-dependent parameters can be measured. It is suggested that some of the more general techniques used in the study of metabolic systems may be useful in pharmacokinetics.

Drug Administration Schedule↗
PubMed1995

p53 gene mutations, p53 protein accumulation and compartmentalization in colorectal adenocarcinoma.

p53 accumulation may occur in the nucleus and/or cytoplasm of neoplastic cells. Cytoplasmic accumulation has been reported to be an unfavorable, but not established, prognostic indicator in colorectal cancer. Different types of p53 intracellular compartmentalization could depend either on p53 gene mutations or on the interaction with p53 protein ligands. The purposes of our study were (1) to assess whether the different patterns of p53 accumulation are selectively associated with p53 mutations and (2) to evaluate the clinical significance of p53 mutations in colorectal carcinomas. We evaluated p53 gene mutations in colorectal carcinomas. We evaluated p53 gene mutations in exons 5 through 8, by polymerase chain reaction and single-strand conformation polymorphism analysis; p53 accumulation and intracellular compartmentalization were detected immunocytochemically with the antibodies PAb1801 and CM1. p53 mutations were found in 74 of 126 carcinomas (59%). Nuclear p53PAb1801 accumulation was associated with p53 gene mutations (P < 0.001) whereas cytoplasmic p53 CM1 accumulation was more likely to occur with the wild-type p53 gene (P = 0.048). Overall, 112 carcinomas (89%) displayed p53 gene mutations and/or p53 accumulations of any type. p53 mutations were not correlated with important clinicopathological parameters and were not related to patient survival. Our data suggest that mechanisms other than mutations may also play a role in inhibiting p53 tumor-suppressing functions in colorectal carcinomas. Cytoplasmic p53CM1 accumulation frequently does not depend on p53 mutations.

Adenocarcinoma↗
PubMed1994

Functional consequences of compartmentalization of synaptic input.

Intra-axonal recordings of stomatogastric nerve axon 1 (SNAX1) indicate that there are synaptic inputs onto the SNAX1 terminals in the stomatogastric ganglion (STG) of the crab Cancer borealis (Nusbaum et al., 1992b). To determine whether this synaptic input only influenced SNAX1 activity within the STG, we identified the SNAX1 soma in the commissural ganglion (CoG). We found that this neuron has a neuropilar arborization in the CoG and also receives synaptic inputs in this ganglion. Based on its soma location, we have renamed this neuron modulatory commissural neuron 1 (MCN1). While intracellular stimulation of MCN1soma and MCN1SNAX has the same excitatory effects on the STG motor patterns, MCN1 receives distinct synaptic inputs in the STG and CoG. Moreover, the synaptic input that MCN1 receives within the STG compartmentalizes its activity. Specifically, the lateral gastric (LG) neuron synaptically inhibits MCN1SNAX-initiated activity within the STG (Nusbaum et al., 1992b), and while LG did not inhibit MCN1soma-initiated activity in the CoG, it did inhibit these MCN1 impulses when they arrived in the STG. As a result, during MCN1soma-elicited gastric mill rhythms, MCN1soma is continually active in the CoG but its effects are rhythmically inhibited in the STG by LG neuron impulse bursts. One functional consequence of this local control of MCN1 within the STG is that the LG neuron thereby controls the timing of the impulse bursts in other gastric mill neurons. Thus, local synaptic input can functionally compartmentalize the activity of a neuron with arbors in distinct regions of the nervous system.

Animals↗
PubMed1996

Chylomicron metabolism in rats: lipolysis, recirculation of triglyceride-derived fatty acids in plasma FFA, and fate of core lipids as analyzed by compartmental modelling.

Chylomicrons labeled in vivo with [14C]oleic acid (primarily in triglycerides (TG), providing a tracer for lipolysis) and [3H]retinol (primarily in ester form, providing a tracer for the corelipids) were injected into rats. Disappearance of the two labels from plasma and appearance of label in plasma free fatty acids (FFA) were analyzed by compartmental modelling. Both core and TG label distributed into an apparent volume 10-15% larger than the blood volume. Part of this probably represents margination to endothelial-binding-lipolysis sites. An open two-compartmental model for plasma FFA was derived from experiments where unesterified oleic acid complexed to albumin was injected. Applying this model revealed that most of the oleic acid from chylomicron triglycerides mixes with the FFA. The disappearance of chylomicron core label required a model in which the label transfers into a second compartment before it leaves the blood. The rate constant for the transformation was high and predicted that, on average, chylomicron spent less than 2 min in the first compartment. The rate out from the second compartment predicted that about 60% of the core label left blood while, on average, chylomicron retained more than half of its triglyceride molecules, i.e., after rather limited lipolysis. The mechanism by which the core label leaves blood is not clear. Modelling showed that under the assumption that the process is shared by chylomicron triglycerides, about half of them go out by this pathway. Comparing fed and fasted rats, the main differences were in the turnover of FFA and in the extent to which chylomicron TG label reappeared in the FFA. This study indicates that a large fraction of the triglycerides in chylomicrons leave plasma together with the core lipids and that most of the fatty acids from chylomicron triglycerides mix into the same metabolic compartments as do plasma free fatty acids.

Animals↗
PubMed1996

Computing marginal expectations for large compartmentalized models with application to AIDS evolution in a prison system.

The customary models for the AIDS epidemic are compartmentalized according to criteria such as risk factors, sexual habits, gender, race, age, and HIV status and stage. Hitherto, with very few exceptions, investigators have resorted to deterministic approximations or to simulation for the computational investigation of such models, which do not yield to purely analytic methods. The present paper describes a numerical technique, not dependent on Monte Carlo simulations, for such compartmentalized Markov population processes. Analytic error bounds and computational evidence suggest that this technique is quite accurate. The study is motivated and illustrated by a model for a prison system, with ten interrelated prisons, twenty compartments, and thousands of individuals. This model is of increasing interest in itself because the HIV/AIDS epidemic is particularly virulent among prison populations, where the environment offers special opportunities to investigate various prevention and educational programmes quantitatively. Our computational techniques are shown to be effective for the analysis of such a prison system, even though the resulting Markov process is an order of magnitude more complicated than other stochastic epidemic models currently being investigated. The modelling approach and numerical device appear to be applicable to a wide variety of population processes involving migration between population patches.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Dependence on intracellular pH and Mg2+ of metabolic compartmentation of phosphoinositides in human erythrocytes.

Effects of intracellular pH and Mg2+ on turnover and extent of metabolic compartmentation of phosphomonoester groups of phosphoinositides and phosphatidate were investigated in human erythrocytes by short-term and equilibrium labeling with [32P]Pi under steady-state conditions. At pH 6.7, the specific radio-activities of phosphoinositides reached apparent equilibrium values, in the range of 70% of that ATP-gamma-P after long-term labelling. At pH 7.2, these values were in the range of 40-50% of that ATP-gamma-P. This demonstrates a decreased accessibility of phosphoinositides to enzymatic phosphorylation and dephosphorylation at the transition from acidic to normal incubation conditions. These changes were more pronounced at pH 7.8. High intracellular [Mg2+] initially activated the turnover of phosphoinositides at pH 7.2. The activation changed into an inhibition and an increase of metabolic compartmentation after three hours preincubation of erythrocytes at high [Mg2+]. The long-term Mg2+ effects are reversible to a great extent by a subsequent re-reduction of [Mg2+]. In conclusion, deprotonation of phosphoinositides by low [H+] or high intracellular [Mg2+] at normal pH induces a decreased accessibility for their specific lipid kinases and phosphatases. This effect may be the result of lateral phase separation of acidic phospholipids as a consequence of divalent cation complexation under both experimental conditions, high pH and high [Mg2+] at normal pH.

Erythrocytes↗
PubMedDate not supplied

Intravillous eicosanoid compartmentalization and regulation of placental blood flow.

OBJECTIVE: To determine the roles of the eicosanoids thromboxane and prostacyclin, and their compartmentalization, in the regulation of placental blood flow. METHODS: First, the sites of production of thromboxane and prostacyclin were determined within the placental villus using immunohistochemical staining for thromboxane and prostacyclin synthetase. Second, the production of both eicosanoids was studied in cultured trophoblasts and compared with that in the villous core by measuring the metabolites thromboxane B2 and 6-keto-prostaglandin F 1 alpha. Finally, eicosanoid production was assessed in intact villi after stimulation by an acute change in oxygen content, 5% to 95%. RESULTS: Immunohistochemical staining showed that thromboxane production was primarily within the trophoblasts, whereas prostacyclin production was localized to the endothelial cells within the villi. In culture, we found preferential production of prostacyclin by the villous core cells and increased production of thromboxane by trophoblasts. Perifusion of intact villi demonstrated increased production of thromboxane by trophoblasts in response to an increase in oxygen content. Prostacyclin levels were too low to be detected. CONCLUSIONS: Placental blood flow appears to be regulated by compartmentalized eicosanoids, with thromboxane affecting primarily the maternal side of the placental circulation and prostacyclin affecting primarily the fetal side.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Compartmentalized transcription and the establishment of cell type during sporulation in Bacillus subtilis.

An early step in sporulation of the bacterium Bacillus subtilis, is the formation of two compartments in the developing sporangium: the mother cell and the forespore. These compartments differ in their programs of gene expression and developmental fate. The establishment of cell type within this simple developmental program, is accomplished by the compartmentalization of sigma subunits of RNA polymerase. The localization of these sigma factors results in compartment-specific gene expression. Recent experiments have elucidated some of the early steps in the establishment of cell type. After septum formation, the activity of the sigma factor, sigma F, is confined to the forespore compartment. This, in turn, results in the localized expression of another developmental sigma factor, sigma G. The forespore localization of these two sigma factors, establishes the forespore line of gene expression. sigma F and sigma G also regulate mother cell events. sigma F activity in the forespore regulates the proteolytic processing of sigma E within the mother cell compartment. The localization sigma E activity leads to mother cell expression of another sigma factor, pro-sigma K. The proteolytic processing of pro-sigma K to mature sigma K is controlled by the forespore sigma factor, sigma G. Mature sigma K then directs the transcription of mother cell specific genes. Therefore, the initial localization of sigma F activity to the forespore compartment, orchestrates the establishment of cell type in both forespore and mother cell compartments.

Bacillus subtilis↗