Urocanic acid and formimino-glutamic acid excretion in megaloblastic anaemia and other conditions: the effect of specific therapy

Metabolomic analysis of significant changes in Lactobacillus casei Zhang during culturing to generation 4,000 under conditions of glucose restriction

Lactic acid bacteria are being consumed more frequently as awareness of their health benefits has increased. The industrial production of lactic acid bacteria requires a comprehensive understanding of their survival stress, especially regarding changes in metabolic substances in a glucose-limited environment. In the present study, a metabolomic approach was applied to investigate Lactobacillus casei Zhang using cultures from a common ancestor that were permitted to evolve under conditions with normal or glucose-restricted media for up to 4,000 generations. Metabolomic analyses of intracellular and extracellular differential metabolites under De Man, Rogosa and Sharpe broth (2% vol/vol glucose; Oxoid Ltd., Basingstoke, UK) and glucose-restricted (0.02% vol/vol glucose in De Man, Rogosa and Sharpe broth) conditions were performed at generations 0, 2,000, and 4,000 and revealed 23 different metabolites. Myristic acid, ergothioneine, Lys-Thr, and palmitamide contents exhibited significant reductions between 0 and 4,000 generations, whereas nicotinate, histidine, palmitic acid, l-lysine, urocanate, thymine, and other substances increased. The dynamics of the pathways involved in AA metabolism, including glycine, serine, and threonine metabolism, histidine metabolism, lysine degradation, and arginine and proline metabolism, were also a focus of the present study. There were also changes in several other metabolic pathways, including vitamin B₆, thiamine, nicotinate, and nicotinamide, according to generation time. Additionally, in the present study we screened for key metabolites involved in the glucose-restricted response and provided a theoretical basis for comprehensively revealing the regulatory mechanisms associated with L. casei Zhang glucose restriction at the metabolic level. These findings also provide novel ideas and methods for analyzing the glucose-restricted stress response at the metabolic level.

Urocanate as a potential signaling molecule for bacterial recognition of eukaryotic hosts

Host recognition is the crucial first step in infectious disease pathogenesis. Recognition allows pathogenic bacteria to identify suitable niches and deploy appropriate phenotypes for successful colonization and immune evasion. However, the mechanisms underlying host recognition remain largely unknown. Mounting evidence suggests that urocanate-an intermediate of the histidine degradation pathway-accumulates in tissues, such as skin, and acts as a molecule that promotes bacterial infection via molecular interaction with the bacterial regulatory protein HutC. In Gram-negative bacteria, HutC has long been known as a transcriptional repressor of hut genes for the utilization of histidine (and urocanate) as sources of carbon and nitrogen. Recent work on the opportunistic human pathogen Pseudomonas aeruginosa and zoonotic pathogen Brucella abortus shows that urocanate, in conjunction with HutC, plays a significant role in the global control of cellular metabolism, cell motility, and expression of virulence factors. We suggest that in addition to being a valuable source of carbon and nitrogen, urocanate may be central to the elicitation of bacterial pathogenesis.

DETECTION OF FORMIMINO-GLUTAMIC AND UROCANIC ACIDS IN URINE BY MEANS OF THIN-LAYER CHROMATOGRAPHY

A simple and rapid method has been developed for the simultaneous separation and semi-quantitative estimation of formimino-glutamic and urocanic acids in urine. The urinary excretion of these compounds in a group of normal subjects and in a number of illustrative cases has been determined. In view of current opinion that it is the total of these two metabolites of histidine which is the significant figure in clinical investigation, their simultaneous separation and measurement is an important advantage of the method.

Method of assay of red cell folate activity and the value of the assay as a test for folate deficiency

A simplified microbiological assay for determining the folate content of red cells is described. As in previously reported methods Lactobacillus casei is used as test organism but two modifications are introduced. First, haemolysis is carried out in water containing 1 g.% of ascorbic acid; secondly, haemolysates are not incubated before the assay. Using this assay, recovery of pteroylglutamic acid added in two different concentrations to five different whole blood samples was 97.0 +/- 1.9 S.E. % and 106.1 +/- 4.7 S.E. % respectively. The coefficient of variation of the assay was between 11.2 and 15.0%. Haemolysates were best stored deep frozen, showing no significant loss of L. casei activity for three to five months at -20 degrees C. On the other hand, non-haemolysed blood samples were best stored at 4 degrees C. when there was no loss of activity for seven to 10 days. Experiments confirmed that plasma is necessary for the maximum release of red cell L. casei activity, and showed that only small amounts of plasma are necessary; folate- and B(12)-deficient plasma released slightly lower L. casei activities from red cells than did normal plasma. The red cell folate levels of 40 healthy normal subjects ranged from 160 to 640 mmug. per ml. of packed red cells. One hundred and twenty patients with subnormal serum folate levels due to idiopathic steatorrhoea, nutritional folate deficiency and Crohn's disease, partial gastrectomy, myelosclerosis, and polycythaemia vera were studied. Red cell folate levels were subnormal (range from 7 to 143 mmug. per ml.) in 40 patients with megaloblastic anaemia, the lowest levels occurring in the most anaemic patients. Subnormal red cell folate levels also occurred in 23 (29%) of the 80 non-anaemic patients. There was a good correlation between red cell folate level and severity of folate deficiency assessed by polymorph nuclear lobe counts, and, in the non-anaemic patients bone marrow morphology. It is concluded that, in the absence of B(12) deficiency, the red cell folate level is a precise guide to the severity of folate deficiency. Patients with serum folate levels less than 3.0 mmug. per ml. almost always had megaloblastic anaemia or obvious morphological changes of folate deficiency. In patients with borderline serum folate levels (3.0-5.9 mmug. per ml.) haematological changes varied widely. The degree of change correlated with the red cell folate level in these patients. The formiminoglutamic acid (Figlu) test was positive (range 20-660 mg. excreted in eight hours) in all 30 patients with megaloblastic anaemia due to folate deficiency tested and also in 17 (31%) of 54 non-anaemic patients who were folate deficient. The amount of Figlu excreted paralleled the red cell folate level in both the anaemic and non-anaemic, folate-deficient patients tested. Figlu excretion, like the red cell folate level, appeared to be a satisfactory index of tissue folate stores. In 46 patients with pernicious anaemia, the red cell folate levels ranged from 26 to 396 mmug. per ml., 29 (63%) of them having subnormal levels. The ratio of mean red cell to mean serum folate level, 13.0:1, was lower than that of normal subjects. As in folate deficiency the patients with the lowest haemoglobin concentrations had the lowest red cell folate levels. Figlu was positively excreted in 10 (59%) of 17 patients with pernicious anaemia tested, being particularly increased in those with low red cell folate levels. Reticulocytes of patients with pernicious anaemia on treatment and with haemolytic anaemia were shown to have higher folate levels than their corresponding mature cells. It is concluded that reticulocytes in general have relatively high folate levels.

Relative importance of formiminoglutamic and urocanic acid excretion after a histidine load

A thin-layer chromatographic method for the simultaneous assessment of formimino-glutamic (Figlu) and urocanic acid excretion after loading with 15 g. histidine has been applied to 15 control subjects and to 49 selected patients. Upper limits of normal excretion were determined for urocanic acid and Figlu alone (15 mg. and 30 mg/8 hr. respectively), and for the combined metabolites (40 mg./8 hr.). Of the 49 patients studied, 27 excreted total metabolites above 40 mg./8 hr.; of these 19 would have been revealed by their abnormal excretion of Figlu and 22 by their abnormal excretion of urocanic acid. Of 74 tests in the 64 subjects, urocanic acid was present in all but 27% of the tests, and in 29.8% of the tests urocanic acid was in excess of the amount of Figlu excreted. In six normal and six abnormal tests urocanic acid was the sole metabolite present. These results re-emphasize the value of estimating both histidine metabolites in tests for folate deficiency in man, and underline the greater relative importance of urocanic acid.

Human cadaveric renal transplantation. Report of twenty cases

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