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N-carbamylglutamate protects patients with decompensated propionic aciduria from hyperammonaemia.

In patients with propionic aciduria, the accumulating metabolite propionyl-CoA causes a disturbance of the urea cycle via the inhibition of N-acetylglutamate synthesis. Lack of this allosteric activator results in an inhibition of carbamoylphosphate synthase (CPS). This finally leads to hyperammonaemia. In two patients with decompensated propionic aciduria the CPS activator carbamylglutamate was tested for its ability to antagonize the propionyl-CoA associated hyperammonaemia. Oral carbamyl glutamate administration resulted in a significant increase in ammonia detoxification and could avoid further dialysis therapy. Safe, fast and easy to administer, carbamyl glutamate improves the acute therapy of decompensated propionic aciduria by increasing ammonia detoxification and avoiding hyperammonaemia.

Glutamates↗

Propionic acid induces cytoskeletal alterations in cultured astrocytes from rat cerebral cortex.

Severe neurological symptoms, cerebral edema, and atrophy are common features of the inherited metabolic disorder propionic acidemia. However, the pathomechanisms involved in the neuropathology of this disease are not well established. In this study, we investigate the effects of propionic acid (PA), a metabolite accumulating in this disorder, on cytoskeletal reorganization, on cell viability, and on the in vitro phosphorylation of glial fibrillary acidic protein (GFAP) and vimentin in cultured astrocytes from cerebral cortex of neonatal rats. We observed that the astrocytes changed their usual polygonal morphology when exposed to 5 mM PA for 72 h, leading to the appearance of fusiform or process-bearing cells, without elicit cell death. We also noticed that after 72 h treatment with 5 mM PA cells showed retracted cytoplasm with bipolar processes containing packed GFAP filaments and disorganized actin stress fibers, as revealed by immunocytochemistry. In addition, the morphological alterations were accompanied by increased in vitro 32P incorporation into GFAP and vimentin recovered into the high-salt Triton-insoluble cytoskeletal fraction. In conclusion, our results indicate that PA lead to cytoskeletal reorganization and to increased in vitro phosphorylation of Triton-insoluble GFAP and vimentin. On the basis of our results we could suppose that Triton-insoluble GFAP and vimentin hyperphosphorylation could be implicated in the reorganization of cellular structure and these findings could be involved in the brain damage characteristic of propionic acidemia patients.

Actin Cytoskeleton↗

The relative contribution of propionate, and long-chain even-numbered fatty acids to the production of long-chain odd-numbered fatty acids in rumen bacteria.

1. The relative contribution of propionate, and long-chain even-numbered fatty acids to the production of long-chain odd-numbered fatty acids in six pure cultures of rumen bacteria were studied, using single and double isotope procedures. 2. Both propionate and even-numbered fatty acids were converted to odd-numbered fatty acids, presumably by elongation of 2-C atoms and alpha-oxidation reactions, but even-numbered fatty acids were much more effective. 3. The occurrence of alpha-oxidation was further confirmed by relatively large quantities of 14CO2 produced when [1-14C]palmitate was used in the incubation medium. 4. The incorporation of propionate into odd-numbered fatty acids was markedly reduced in the presence of palmitate, or stearate. 5. The significance of the operation of alpha-oxidation is discussed in relation to the energy conservation in rumen bacteria.

Animals↗

Uncoupling of CA3 pyramidal neurons by propionate.

The influence of cytoplasmic acidification on dye-coupling between CA3 pyramidal neurons was examined by Lucifer yellow injections in guinea pig hippocampal brain slices. Neurons were believed to be acidified by exposure to 100 mM propionate. Dye-coupling was reduced significantly to 6% (n = 35) in propionate versus 28% (n = 39) in control solution (P less than 2%). Propionate may be a useful tool for experimental manipulation of coupling in the mammalian CNS.

Animals↗

Detection of propionic acid vapor by rats with lesions of olfactory bulb areas associated with high 2-DG uptake.

This study tested the functional significance of recent 2-deoxyglucose (2-DG) results demonstrating a discrete focus of activity in the olfactory bulb of rats exposed to the vapor of propionic acid. Rats with lesions that destroyed this area of the olfactory bulb performed as well as did sham operated and lesioned controls in detection of amyl acetate, butanol, geraniol, propionic acid, and on a test for propionic acid threshold. Our results demonstrate that an area of the olfactory bulb containing a major focus of metabolic activity induced by exposure to an odor can be removed without producing a deficit in the detection of that odor.

Animals↗

Cholesterogenesis from propionate: facts and speculations.

Cholesterogenesis from [1-14C]acetate and [2-14C]propionate by the liver and adipose tissue has been studied in vitro. In all species tested including the rat, mouse, chicken, cow and pig, labelled propionate was recovered in cholesterol following the same trend as acetate, but at lower incorporation rates. Chicken liver was the most active in incorporating both substrates into cholesterol. In the cow and pig, the rates of cholesterol synthesis were higher in the adipose tissue than in the liver. Three alternative mechanisms are proposed to explain the recovery of propionate in cholesterol.

Acetates↗

The effects of propionate and butyrate on acetate metabolism in rat hepatocytes.

1. Two mM propionate or butyrate inhibited the mitochondrial uptake of acetate by rat hepatocytes. 2. With propionate the inhibition was so strong that the net formation of acetate in the cytoplasm, usually masked by the mitochondrial uptake, appeared directly as a net output of acetate into the medium; showing that this net formation of acetate, reported by [Crabtree B., Gordon M.-J. and Christie S. L. (1990) Biochem. J. 270, 219-225] is not an artefact arising from a misinterpretation of isotopic data. 3. The results also suggest that propionate and butyrate inhibit peroxisomal metabolism.

Acetates↗

Determination of propionate in bread using capillary zone electrophoresis.

A method for the determination of propionate in bread is described. The propionate was extracted from the bread with a repeated extraction procedure and measured using capillary zone electrophoresis in the indirect UV mode applying a background electrolyte of 0.005 M Tris adjusted at pH 4.6 by adding benzoic acid. Using laboratory-baked bread containing known amounts of sodium propionate, recoveries of ca. 95% could be established, validating the method.

Bread↗

Antimutagenicity of propionic acid bacteria.

The antimutagenic effect of dialysed cell extracts of 4 strains of propionic acid bacteria was examined against the mutagenicity of sodium azide in the TA1535 tester strain of Salmonella typhimurium using the Ames test. It was noted that dialysates of 2 strains of Propionibacterium shermanii, P. pentosaceum and P. acnes, significantly reduced sodium azide-induced revertants. The dialysate of propionic acid cocci did not show an antimutagenic effect. The inhibitory activity was enhanced if the mutagen and extract were coincubated for 20 min prior to performing the mutagenicity assay. Antimutagenicity of dialysates from P. shermanii VKM-103 against MNNG and 9-aminoacridine was shown in S. typhimurium strains TA1535 and TA97. The antimutagenic activity was found in the protein fraction of the cell extract of P. shermanii. The proteins of the dialysate of P. shermanii were separated using a Toyopearl gel column into 3 main peaks according to their molecular weights. The antimutagenic activity towards sodium azide was found in the second and the third peaks. We suggest that dialysates of the cells of propionic acid bacteria contain several kinds of antimutagenic substances with different molecular weights.

Aminacrine↗

Inhibition of aromatase activity and of endocrine-responsive tumor growth by 10-propargylestr-4-ene-3, 17-dione and its 17-propionate derivative.

Two androstenedione derivatives, 10-propargylestr-4-ene-3,17-dione and its 17-propionated form, were administered to normal cycling rats, and both compounds led to an inhibition of ovarian aromatase. Under in vitro conditions, only the former compound exhibited high potency as an inhibitor of rat ovarian and human placental microsomal aromatase. At 1 mg/kg/day both compounds were effective in promoting regression of 9,10-dimethyl-1,2-benzanthracene-induced mammary tumors in rats without terminating their estrous cycle. PED also inhibited growth of a human ovarian carcinoma in athymic mice. The results with the 17-propionated compound testify to the necessity of in vivo assays in screening antitumor agents. In summary, PED and its propionated derivative inhibited ovarian aromatase in vivo and inhibited the growth of hormone-responsive tumors.

Androstenedione↗

Screening of the food additive propionic acid for genotoxic properties.

Genotoxic properties of the food additive propionic acid were analysed using the Escherichia coli DNA repair assay, the SOS chromotest, the Salmonella/microsome mutagenicity test, the sister chromatid exchange test in vitro and the micronucleus test in vivo. All tests except the DNA repair assay with E. coli yielded negative results. These data support other evidence that propionic acid is not mutagenic and that genotoxic events are unlikely to be the cause of forestomach lesions in rats fed propionic acid in the diet (Griem, Bundesgesundheitsblatt 1985, 28, 322).

Animals↗

Early changes in the forestomach of rats, mice and hamsters exposed to dietary propionic and butyric acid.

Groups of five male and five female rats, mice and hamsters were fed diet containing 4% propionic or butyric acid for 7 days. Evidence of damage and cellular proliferation in the epithelium of the forestomach and limiting ridge was detected in all three species. Changes were particularly marked in animals fed butyric acid diet and rats appeared to be the most sensitive species. It is postulated that tumours of the forestomach reported in rats after long-term feeding of propionic acid diet may be a consequence of continued damage and repair, and that butyric acid, which occurs naturally in foods at concentrations up to 5%, would be at least as potent as propionic acid if similarly tested.

Administration, Oral↗

Plasma insulin and glucagon responses to acute challenges of acetate, propionate, n-butyrate and glucose in growing gilts (Sus scrofa).

A supraphysiological dose (2.5 mmol kg-1 body weight) of acetate, propionate, n-butyrate or glucose was intravenously injected to measure plasma insulin and glucagon responses in growing gilts. Plasma insulin concentrations remained constant after injection of the volatile fatty acids. Plasma glucagon concentrations increased (P < 0.05) after n-butyrate injection following an initial temporary decrease (P < 0.05), and showed a similar tendency after acetate or propionate injection. These results suggest that a supraphysiological dose of acetate, propionate or n-butyrate may stimulate a plasma glucagon response in growing piglets.

Acetates↗

14C-propionate incorporation assay by rapid filtration in multiwell plates.

BACKGROUND: Methylmalonic aciduria (MMA) is divided into two groups according to cobalamin dependency, and this classification is important for treatment. Unfortunately, there has been no rapid and reliable method for the evaluation of cobalamin dependency. METHODS: [14C]-propionate incorporation into intact cells in the presence of either media alone or media containing various amounts of cobalamin was measured using a 96-well filtration plate and vacuum manifold. Incorporation of radioactivity was measured by direct microplate scintillation. RESULTS: Using peripheral white blood cells from normal individuals, we obtained a linear relationship between the rate of 14C-propionate incorporation and the number of cells over a broad range (10,000 to 100,000 cells/well). 14C-propionate incorporation in cells from eight patients was 1% to 13% of parallel controls. CONCLUSIONS: In this report, we describe a rapid, sensitive and reliable method for evaluating the cobalamin dependency of methylmalonic aciduria.

Age of Onset↗

Development of a Corynebacterium glutamicum DNA microarray and validation by genome-wide expression profiling during growth with propionate as carbon source.

A DNA microarray was developed to analyse global gene expression of the amino acid-producing bacterium Corynebacterium glutamicum. PCR products representing 93.4% of the predicted C. glutamicum genes were prepared and spotted in quadruplicate onto 3-aminopropyltrimethoxysilane-coated glass slides. The applicability of the C. glutamicum DNA microarray was demonstrated by co-hybridisation with fluorescently labelled cDNA probes. Analysis of the technical variance revealed that C. glutamicum genes detected with different intensities resulting in ratios greater than 1.52 or smaller than -1.52 can be regarded as differentially expressed with a confidence level of greater than 95%. In a validation example, we measured changes of the mRNA levels during growth of C. glutamicum with acetate and propionate as carbon sources. Acetate-grown C. glutamicum cultures were used as reference. At the 95% confidence interval, 117 genes revealed increased transcript levels in the presence of propionate, while 43 genes showed a decreased expression compared with the acetate-grown culture. Global expression profiling confirmed the induction of the prpD2B2C2 gene cluster already known to be essential for propionate degradation via the 2-methylcitrate cycle. Besides many genes of unknown function, the paralogous prpD1B1C1 gene cluster as well as fasI-B (encoding fatty-acid synthase IB), dtsR1 and dtsR2 (components of acyl-CoA carboxylases), gluABCD (glutamate transport system), putP (proline transport system), and pyc (pyruvate carboxylase) showed significantly increased expression levels. Differential expression of these genes was confirmed by real-time reverse transcription (RT) PCR assays.

Carbon↗

The role of the heme propionates in heme biochemistry.

There are numerous studies, relying on both experimental and theoretical observations, illustrating the active role of the heme propionates in regulating electron delivery to the iron center as well as biochemical properties of the heme. Evidences for this come from a wide variety of heme containing systems: cytochromes, heme peroxidases, globins, etc. Here, we shortly summarize these studies and revisit previous theoretical calculations (V. Guallar, M.H. Baik, S.J. Lippard, R.A. Friesner, Proc. Natl. Acad. Sci. USA 100 (2003) 6998-7002) where the propionate groups induced the delocalization of the spin density in the cytochrome P450cam putative active species, Compound I. We introduce novel data, obtained by means of mixed quantum mechanics and molecular mechanics methods, indicating a larger electron delocalization into the protein. We also present novel results based on the recent migration of spin density observed by Barrows et al. (T.P. Barrows, T.L. Poulos, Biochemistry 44 (2005) 14062-68) on an ascorbate peroxidase mutant. All this data strongly supports the importance of the propionate groups in tuning the heme electronic properties.

Ascorbate Peroxidases↗

Propionic acid induces convulsions and protein carbonylation in rats.

Propionic acid (PA) accumulates in patients with propionic acidemia, an inherited metabolic disorder caused by the deficiency of propionyl-CoA carboxylase activity that is clinically characterized by neurological dysfunction, including seizures. However, it is not known whether PA causes seizures in experimental animals. In the current study, we investigated whether intrastriatal injection of PA (0.6-6 micromol) causes seizures and alters protein carbonyl content in the striatum of adult rats. The injection of PA caused the appearance of seizures and increased protein carbonyl content in injected and noninjected striata. PA-induced seizures and increased protein carbonylation in the striatum were prevented by the injection of MK-801 (3 nmol/0.5 microL). Our results suggest that PA causes seizures and oxidative damage by NMDA receptor-mediated mechanisms. The involvement of NMDA receptors in the pathogenesis of propionic acidemia is suggested.

Animals↗

Candidatus "Anammoxoglobus propionicus" a new propionate oxidizing species of anaerobic ammonium oxidizing bacteria.

The bacteria that mediate the anaerobic oxidation of ammonium (anammox) are detected worldwide in natural and man-made ecosystems, and contribute up to 50% to the loss of inorganic nitrogen in the oceans. Two different anammox species rarely live in a single habitat, suggesting that each species has a defined but yet unknown niche. Here we describe a new anaerobic ammonium oxidizing bacterium with a defined niche: the co-oxidation of propionate and ammonium. The new anammox species was enriched in a laboratory scale bioreactor in the presence of ammonium and propionate. Interestingly, this particular anammox species could out-compete other anammox bacteria and heterotrophic denitrifiers for the oxidation of propionate in the presence of ammonium, nitrite and nitrate. We provisionally named the new species Candidatus "Anammoxoglobus propionicus".

Bacteria, Anaerobic↗