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PubMed2004

Alkaliflexus imshenetskii gen. nov. sp. nov., a new alkaliphilic gliding carbohydrate-fermenting bacterium with propionate formation from a soda lake.

Anaerobic saccharolytic bacteria thriving at high pH values were studied in a cellulose-degrading enrichment culture originating from the alkaline lake, Verkhneye Beloye (Central Asia). In situ hybridization of the enrichment culture with 16S rRNA-targeted probes revealed that abundant, long, thin, rod-shaped cells were related to Cytophaga. Bacteria of this type were isolated with cellobiose and five isolates were characterized. Isolates were thin, flexible, gliding rods. They formed a spherical cyst-like structure at one cell end during the late growth phase. The pH range for growth was 7.5-10.2, with an optimum around pH 8.5. Cultures produced a pinkish pigment tentatively identified as a carotenoid. Isolates did not degrade cellulose, indicating that they utilized soluble products formed by so far uncultured hydrolytic cellulose degraders. Besides cellobiose, the isolates utilized other carbohydrates, including xylose, maltose, xylan, starch, and pectin. The main organic fermentation products were propionate, acetate, and succinate. Oxygen, which was not used as electron acceptor, impaired growth. A representative isolate, strain Z-7010, with Marinilabilia salmonicolor as the closest relative, is described as a new genus and species, Alkaliflexus imshenetskii. This is the first cultivated alkaliphilic anaerobic member of the Cytophaga/ Flavobacterium/ Bacteroides phylum.

Acetic Acid↗
PubMed1996

Purification and characterization of fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB.

Fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB was purified 130-fold under anoxic conditions. The native enzyme had an apparent molecular mass of 114 kDa and was composed of two subunits of 60 kDa. The enzyme exhibited maximum activity at pH 8.5 and approximately 54 degrees C. The Km values for fumarate and L-malate were 0.25 mM and 2.38 mM, respectively. Fumarase was inactivated by oxygen, but the activity could be restored by addition of Fe2+ and β-mercaptoethanol under anoxic conditions. EPR spectroscopy of the purified enzyme revealed the presence of a [3Fe-4S] cluster. Under reducing conditions, only a trace amount of a [4Fe-4S] cluster was detected. Addition of fumarate resulted in a significant increase of this [4Fe-4S] signal. The N-terminal amino acid sequence showed similarity to the sequences of fumarase A and B of Escherichia coli (56%) and fumarase A of Salmonella typhimurium (63%).

Amino Acid Sequence↗
PubMed2003

The impact of screening for propionic and methylmalonic acidaemia.

UNLABELLED: The outcome of the severe variants of propionic and methylmalonic acidaemia is not good. Patients with these disorders have increased concentrations of propionylcarnitine and using tandem mass spectrometry to detect this compound, it is possible to screen in the newborn period. Various criteria have been used to identify the patients but only a small number of patients have been diagnosed so far and some have been missed. Furthermore many will have already presented before the result of the screening test is available. CONCLUSION: It is not yet clear whether the outcome is better for those identified in screening programmes.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Qualitative and quantitative analysis of the effect of splicing mutations in propionic acidemia underlying non-severe phenotypes.

In this work we analyze splicing mutations identified in propionic acidemia patients to clarify their functional effects and their involvement in the disease phenotype. Two mutations in the PCCA gene detected in homozygous patients and involving consensus splice sequences (IVS21+3del4 and IVS22-2A>G) were shown to produce some normal splicing in patients' cells, at very low levels, which were quantitated by real-time PCR methods, and which presumably are sufficient to moderate the phenotype. We have also analysed the effect of mutations c.653A>G and IVS10-11del6 in the PCCB gene present in heterozygous patients with mild phenotype. The c.653A>G mutation is located in the last codon of exon 6 and interferes with the correct spliceosomal assembly activating a cryptic splice site within exon 6, which leads to an in-frame six-nucleotide deletion (delV217-K218). Minigene analysis and sequence-specific hybridization probes using real-time PCR methods showed that no normally spliced transcript is detectable in the patients' fibroblasts. The IVS10-11del6 mutation shortens the polypyrimidine tract of the 3'-splice site of exon 11, resulting in exon skipping. Some normal transcript is detectable by allele-specific hybridization probes. These analyses suggest that, in some cases, the regulation of gene splicing can potentially play an important role in human disease influencing phenotypic parameters.

Amino Acid Metabolism, Inborn Errors↗
PubMed1997

Three novel splice mutations in the PCCA gene causing identical exon skipping in propionic acidemia patients.

Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme involved in the catabolism of branched chain amino acids, odd chain fatty acids, and other metabolites. PCC consists of non-identical subunits, alpha and beta, encoded by the PCCA and PCCB genes, respectively. Inherited deficiency of PCC due to mutations in either the PCCA or the PCCB gene results in propionic acidemia (PA), a clinically heterogeneous disorder with a severe, often lethal, neonatal form, and a mild, later onset form. To characterize PCCA gene mutations responsible for PCC deficiency, we analyzed RT-PCR products obtained from cultured fibroblasts from Spanish PCC-alpha deficient patients. In three patients, smaller than normal PCR products were observed, and sequence analysis revealed the deletion of a 54-bp exon in the cDNA. Sequencing of genomic DNA from these three patients led to the identification of three novel mutations in the PCCA gene, two short deletions and one small insertion, adjacent to short direct repeats, and all of them affecting the consensus splice sites of the skipped exon. These mutations, 1771IVS-2del9, 1824IVS+3del4, and 1824IVS+3insCT, are the cause of the aberrant splicing of the PCCA pre-mRNA and result in an in-frame deletion of 54 nucleotides in the cDNA, probably leading to an unstable protein structure which is responsible for the lack of activity leading to PCC deficiency in these patients.

Amino Acid Metabolism, Inborn Errors↗
PubMed2006

Acidic extracellular pH shifts colorectal cancer cell death from apoptosis to necrosis upon exposure to propionate and acetate, major end-products of the human probiotic propionibacteria.

The human probiotic Propionibacterium freudenreichii kills colorectal adenocarcinoma cells through apoptosis in vitro via its metabolites, the short chain fatty acids (SCFA), acetate and propionate. However, the precise mechanisms, the kinetics of cellular events and the impact of environmental factors such as pH remained to be specified. For the first time, this study demonstrates a major impact of a shift in extracellular pH on the mode of propionibacterial SCFA-induced cell death of HT-29 cells, in the pH range 5.5 to 7.5 prevailing within the colon. Propionibacterial SCFA triggered apoptosis in the pH range 6.0 to 7.5, a lethal process lasting more than 96 h. Indeed at pH 7.5, SCFA induced cell cycle arrest in the G2/M phase, followed by a sequence of cellular events characteristic of apoptosis. By contrast, at pH 5.5, the same SCFA triggered a more rapid and drastic lethal process in less than 24 h. This was characterised by sudden mitochondrial depolarisation, inner membrane permeabilisation, drastic depletion in ATP levels and ROS accumulation, suggesting death by necrosis. Thus, in digestive cancer prophylaxis, the observed pH-mediated switch between apoptosis and necrosis has to be taken into account in strategies involving SCFA production by propionibacteria to kill colon cancer cells.

Acetic Acid↗
PubMed2005

Methylmalonic and propionic acidaemias: management and outcome.

Organic acidurias comprise many various disorders. Methylmalonic aciduria (MMA) and propionic aciduria (PA) are the most frequent diseases and the two organic acidurias for which we have better knowledge of the long-term outcome. Comparing the outcome of patients born before and after 1990, it appears that better neonatal and long-term management have improved the survival rate. Less than 20% of the patients died in either the neonatal period or before the age of 10 years. However, most surviving patients showed poor nutritional status with growth retardation and about 40% present some kind of visceral or neurological impairment. The developmental outcome may have improved in MMA patients, with IQ higher than 75 in about 40% patients aged more than 4 years. Conversely, poor intellectual development is the rule in PA patterns, with 60% having an IQ less than 75 and requiring special education. Successful liver and/or renal transplantations, in a few patients, have resulted in better quality of life but have not necessarily prevented neurological and various visceral complications. These results emphasize the need for permanent metabolic follow-up whatever the therapeutic strategy.

Child, Preschool↗
PubMedDate not supplied

Nutrition therapy of organic acidaemias with amino acid-based formulas: emphasis on methylmalonic and propionic acidaemia.

Failure to thrive has been described in patients with organic acidaemias due to a variety of causes, both organic and inorganic. Failure to thrive in patients with methylmalonic acidaemia (MMA) and propionic acidaemia (PA) may be related to inadequate protein and energy intake rather than pathology of disease. Inadequate protein intake can also result in decreased resting energy expenditure, clinical signs and symptoms of amino acid deficiency, increased risk of infection, and developmental delay. Amino acid-based formulas (also referred to as 'medical foods') provide a key source of nitrogen, energy, vitamins and minerals which, when prescribed appropriately, can promote anabolism and growth. Although protein requirements in patients with organic acidaemias have not been elucidated, providing an adequate balance of protein, energy and other nutrients will help promote growth.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

Methylmalonic and propionic acidurias: management without or with a few supplements of specific amino acid mixture.

In a series of 137 patients with methylmalonic acidaemia (MMA) and propionic acidaemia (PA) diagnosed since the early 1970s, we report in more detail 81 patients (51 MMA and 30 PA) diagnosed between 1988 and 2005. In this series, 14% of patients died at initial access revealing the disease before or despite treatment, 18% died later, and the remainder (68%) are still alive. All patients were treated with the same protocol of enteral feeds with a low-protein diet adjusted to individual tolerance, carnitine, antibiotics, and only occasional use of an amino acid (AA) mixture. There was intensive follow-up and monitoring using measurements of urinary urea. Thirty-nine patients with severe forms, followed for more than 3 years, are analysed in particular detail. Of the 17 PA patients, 6 had moderate disability (all neonatal-onset forms), whereas 11 were normal or slightly delayed in their mental development. Four presented with cardiomyopathy, of whom 2 died. Of the 22 MMA patients, 13 presented in the neonatal period, of whom 3 died later, 2 are in renal failure and only 5 are still alive and have a normal or slightly delayed mental development. In the 9 patients with late-onset forms, there were no deaths and all patients but one have normal mental development. Among the 39 patients, only 40% were given an AA supplement at 3 years, and 50% between 6 and 11 years. The actual intake of natural protein was 0.92, 0.78 and 0.77 g/kg per day at 3, 6 and 11 years, respectively, in patients without AA supplementation, whereas it was 0.75, 0.74 and 0.54 g/kg per day in the group who received small quantities of AA (0.4-0.6 g/kg per day). In both groups, feeding disorders were frequent: 55% at 3 years, 35% at 6 years and 12% at 11 years. Many patients were given a food supplement by tube overnight or were even exclusively tube fed: 60% at 3 years, 48% at 6 years and still 27% at 11 years. Growth velocity was near the normal values. Plasma valine and isoleucine were low to very low, as were leucine and phenylalanine but to a lesser extent. Albumin, vitamins, trace elements and markers of bone metabolism were within the normal values. IGF1, 24-hour urine calcium and body mass density were low. Body composition showed a normal to low lean mass and a normal to high fat mass.

Amino Acid Metabolism, Inborn Errors↗
PubMed1975

Propionate metabolism in fetal livers of 15 to 19 weeks' gestation.

Extracts of hepatic tissue obtained from saline-induced abortuses were analyzed for methylmalonyl CoA carbonylmutase (MM) and propionyl CoA carboxylase (PC) activity. MM activity was similar to control values, which suggests that abortion material may be used to confirm the prenatal diagnosis of methylmalonic acidemia. Confirmation of a presumptive propionic acidemia diagnosis is more tenuous due to the instability of PC and the possibility that saline may induce PC activity.

Abortion, Induced↗
PubMed1983

Retrograde transport of goldfish optic nerve proteins labeled by N-succinimidyl [3H]propionate.

Following injection of the acylating reagent N-succinimidyl [3H]propionate into the optic nerve of goldfish, labeled protein appeared in the ipsilateral retina and contralateral tectum in a time-dependent manner. Autoradiography indicated the presence of the labeled material in the neuroplasm of the retinal ganglion cells and their projections. While most of the recoverable injected radioactivity was confined to the injection site even after 1 week, labeled proteins arriving in the retina by retrograde flow or in the tectum by anterograde flow had distinctly different patterns, a result suggesting specific transport processes rather than diffusion. In contrast to reported studies with the labeling agent in other species, a prominent 68,000 molecular weight component was not seen. The results are discussed in relation to the role of retrograde transport in regeneration.

Animals↗
PubMed1989

Odor-induced metabolic activity in the olfactory bulb of rats trained to detect propionic acid vapor.

The pattern of glucose metabolism in the glomerular layer of the main olfactory bulb was studied in rats trained to sample brief odor stimuli. After injection with [14C]2-deoxyglucose (2-DG). 5 rats were tested for discrimination of propionic acid from air. Over the 45 min test period rats sampled the stimulus for 0.5-0.8s during each trial and their total exposure to the stimulus was 53-147 s. A discrete focus of increased glucose metabolism was found in the central dorsomedial sector of the glomerular layer in each animal. The position of this focus and the overall pattern of glomerular layer activity was essentially identical to that obtained in 4 control rats which were exposed passively to alternating 5 min periods of the odor and clean air for 45 min. The size of the primary focus was only slightly smaller in the trained rats, despite the large difference in total exposure time. The absence of olfactory adaptation during the behavioral tests and the similar pattern of 2-DG uptake in controls and trained animals indicate that adaptation does not play a significant role in the patterns of glucose metabolism induced in the glomeruli of the olfactory bulb by extended exposure to an odor.

Animals↗
PubMed1989

Effect of potassium propionate on free and bound acetylcholine in frog muscle.

Frog sartorius muscles were homogenized under various conditions which allowed, by means of mass spectrometry, the measurement of total ACh, and different ACh compartments in the tissue: 'bound', 'free-1' and 'free-2' ACh. Bound ACh presumably corresponded to the vesicular compartment, and the free-1 and free-2 fractions to the cytoplasmic compartments of ACh. Stimulation of ACh release by La3+ ions for 60 min caused a decrease of both bound and free-2 ACh, but at 20 min bound ACh was reduced much more than free-2 ACh. Stimulation of ACh release by isotonic potassium propionate (KPr) solution for only 5 min caused a decrease of bound ACh, in contrast to free-1 and free-2 ACh which were not significantly changed. When muscles after 5 min stimulation in KPr were allowed to recover in normal Ringer, free-1 ACh did not change, but free-2 and bound ACh increased; after 180 min in Ringer bound ACh had recovered to control values. When ACh synthesis was prevented by hemicholinium-3 during recovery of the muscles in Ringer, bound ACh increased at the expense of free-2 ACh. In deuterium labeling experiments, in which the Ringer contained choline-d9, much more ACh-d9 was formed in stimulated than in unstimulated muscles. It appeared that almost all newly formed ACh was ACh-d9, since no significant synthesis of unlabeled ACh (ACh-d0) took place. Yet again, the amount of bound ACh-d0 significantly increased, apparently at the expense of preformed free-2 ACh-d0.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1980

Immunological studies of propionyl CoA carboxylase in livers and fibroblasts of patients with propionic acidemia.

Antiserum prepared against homogeneous pig heart propionyl CoA carboxylase cross-reacted with human propionyl CoA carboxylase, and was used to demonstrate the presence of immunological cross-reacting material in extracts from the livers of three patients and from fibroblasts of four patients with propionic acidemia representing three major propionyl CoA carboxylase-deficient genetic complementation groups, pcc A, pcc C and bio. Since the quantity of cross-reacting material in the propionyl CoA carboxylase-deficient livers and enzyme-deficient fibroblast cell lines was comparable to that in normal tissues while showing less than five percent of the normal enzyme activity, these patients must synthesize normal or near-normal quantities of an enzymatically inactive propionyl CoA carboxylase protein. In addition, no appreciable change in the amount of cross-reacting material was found in the biotin-responsive bio fibroblasts after incubation with supplemental biotin despite a sixteen-fold increase in enzyme activity suggesting that the defect in the bio mutant involves the activation rather than the synthesis of a pre-existing normal apoenzyme.

Animals↗
PubMed1982

Increased excretion of lactate, glutarate, 3-hydroxyisovalerate and 3-methylglutaconate during clinical episodes of propionic acidemia.

Metabolic changes dependent upon clinical conditions were studied in an eight-month-old girl with propionyl CoA carboxylase deficiency. Only methylcitric acid and 2-methyl-3-oxovaleric acid were detected in the urine of the patient under clinically favorable conditions. During episodes of clinical decompensation, she excreted increased amounts of all the metabolites associated with this disorder. Four acetyl CoA precursors increased during clinical episodes: glutaric acid, a catabolic intermediate of lysine; 3-hydroxyisovaleric acid and 3-methylglutaconic acid, catabolic intermediates of leucine; and lactic acid. This suggests that under clinically favorable conditions the patient has an altered propionate metabolism which proceeds via normal acetyl CoA metabolism with sufficient capacity for acetyl CoA plus propionyl CoA metabolism. When the production of propionyl CoA exceeds the metabolic capacity, however, the catabolism of potent ketogenic amino acids is effectively suppressed in order to reduce acetyl CoA production.

Amino Acid Metabolism, Inborn Errors↗
PubMed1984

Propionylcarnitine excretion in propionic and methylmalonic acidurias: a cause of carnitine deficiency.

Two patients with propionic acidemia (PA) and two patients with methylmalonic aciduria (MMA) had low plasma free carnitine and increased short-chain acylcarnitines. Urinary excretion of free carnitine was decreased, while the excretion of short-chain acylcarnitines, mostly propionylcarnitine , was increased. Carnitine supplementation markedly increased the short-chain acylcarnitine fractions of both plasma and urine. Total carnitine content was decreased in skeletal muscle biopsies obtained from two of the patients. It is suggested that in these organic acidurias mitochondrial propionylcarnitine , formed from free carnitine and excess propionylCoA exchanges with free cytosolic carnitine: propionylcarnitine is then lost in the urine, causing secondary carnitine deficiency in the tissues.

Carnitine↗
PubMed1987

Urinary excretion of 2-methyl-2,3-butanediol and 2,3-pentanediol in patients with disorders of propionate and methylmalonate metabolism.

Urine samples from patients with propionic acidemia and from a patient with methylmalonic acidemia contained unknown non-acidic metabolites by gas chromatography/mass spectrometry after ethyl acetate extraction. It could be demonstrated by mass spectrometric studies and by synthesis of reference compounds that the major metabolite was 2-methyl-2,3-butanediol, while smaller amounts of 2,3-pentanediol were also present. These diols were present in abnormal amounts in these patients during attacks of metabolic decompensation.

Acidosis↗