Hydroxy acid metabolites of branched-chain amino acids in amniotic fluid

A method is described in which ammonia chemical ionization gas chromatography-mass spectrometry was utilized in the selected ion monitoring mode to provide an accurate, selective approach to the quantification in amniotic fluid of a number of hydroxylated organic acids derived from the metabolism of the branched-chain amino acids. 2-Hydroxy-n-caproic acid was employed as an internal standard and the hydroxy acids were isolated from amniotic fluid by liquid partition chromatography and the trimethylsilyl derivatives were quantified. Normal values have been obtained for 2-hydroxyisovaleric acid, the sum of 2-hydroxyisocaproic acid and 2-hydroxy-3-methylvaleric acid, 2-methyl-3-hydroxybutyric acid, 3-hydroxyisovaleric acid and 2-ethyl-3-hydroxypropionic acid. The method also provides data on the concentration of methylmalonic acid. The concentration of 2-hydroxyisovaleric acid was not useful in the prenatal diagnosis of a fetus with maple syrup urine disease. Elevated concentrations of 2-methyl-3-hydroxybutyric acid as well as methylmalonic acid were found in the amniotic fluid of two fetuses with methylmalonic acidemia.     

Quantitative analysis for organic acids in biological samples: batch isolation followed by gas chromatographic-mass spectrometric analysis

This new method for qualitative and quantitative determination of organic acids, aldehydes, and ketones in biological samples is effective for use with urine, plasma, and amniotic fluid, and it requires no deproteinization. Isolation by batch-wise liquid partition chromatography on silicic acid follows formation of the O-(2,3,4,5,6-pentafluorobenzyl)oximes of oxoacids, aldehydes, and ketones. The total organic acid content of the sample provides a rapid screening test for metabolic abnormality. A wide-bore, bonded-phase capillary column was used for quantitative gas chromatographic-mass spectrometric analysis, followed by automated identification and quantification. Analytical recoveries were quantitative for a wide variety of metabolites. Gas-chromatographic retention indices, discriminating ions, and control ranges in amniotic fluid, plasma, and urine of adult subjects were determined for 61 biologically important compounds.     

A rapid assay of 4-hydroxy-3-methoxyphenylglycol in urine.

A rapid and simple gas Chromatographic method is described for the quantitative determination of urinary 4-hydroxy-3-methoxyphenylglycol, employing electron capture detection of the pentafluoropropionyl derivative run on OV 210 and dispensing with an organic solvent extraction step.     

不同孕期羊水间充质干细胞体外培养方法的比较

背景：以往对羊水间充质干细胞的培养多采集孕中期羊水,对妊娠其他阶段羊水进行间充质干细胞培养的研究还很少,特别是系统地对不同孕期羊水和不同培养基进行间充质干细胞培养的效果还未见报道。目的：比较不同孕期羊水中间充质干细胞体外培养的效果。方法：采用两种不同细胞培养基分别对60份妊娠时间为15~42周的羊水进行间充质干细胞的分离培养,观察间充质干细胞培养过程中生长状况及间充质干细胞培养成功率;细胞化学染色法检测间充质干细胞的化学性质;MTT法检测传代后间充质干细胞的生长曲线。结果与结论：采用含体积分数为10%胎牛血清的PRMI-1640培养基和AmnioMAXⅡ complete羊水专用细胞培养基对孕期为37~42周羊水的间充质干细胞培养成功率分别为8%和44%,孕期为21~36周羊水的间充质干细胞成功率分别为20%和60%。而孕期为15~20周的羊水用两种培养基培养成功率为100%。细胞化学染色结果显示：POX、SB（-）,ACP、PAS、AENE（＋）,而NAP有1%为（＋）,不同孕期染色结果无差异。MTT法测定羊水间充质干细胞的生长曲线呈＂S＂形。孕期在15~36周的羊水间充质干细胞可以传15代以上仍然旺盛,而孕期为37~42周的羊水间充质干细胞传10代即表现为生长缓慢。结果表明采用AmnioMAXⅡ complete羊水专用细胞培养基可以明显提高晚期羊水间充质干细胞培养的成功率。羊水的最佳采集时间为15~20周。背景：以往对羊水间充质干细胞的培养多采集孕中期羊水,对妊娠其他阶段羊水进行间充质干细胞培养的研究还很少,特别是系统地对不同孕期羊水和不同培养基进行间充质干细胞培养的效果还未见报道。目的：比较不同孕期羊水中间充质干细胞体外培养的效果。方法：采用两种不同细胞培养基分别对60份妊娠时间为15~42周的羊水进行间充质干细胞的分离培养,观察间充质干细胞培养过程中生长状况及间充质干细胞培养成功率;细胞化学染色法检测间充质干细胞的化学性质;MTT法检测传代后间充质干细胞的生长曲线。结果与结论：采用含体积分数为10%胎牛血清的PRMI-1640培养基和AmnioMAXⅡcomplete羊水专用细胞培养基对孕期为37~42周羊水的间充质干细胞培养成功率分别为8%和44%,孕期为21~36周羊水的间充质干细胞成功率分别为20%和60%。而孕期为15~20周的羊水用两种培养基培养成功率为100%。细胞化学染色结果显示：POX、SB（-）,ACP、PAS、AENE（＋）,而NAP有1%为（＋）,不同孕期染色结果无差异。MTT法测定羊水间充质干细胞的生长曲线呈＂S＂形。孕期在15~36周的羊水间充质干细胞可以传15代以上仍然旺盛,而孕期为37~42周的羊水间充质干细胞传10代即表现为生长缓慢。结果表明采用AmnioMAXⅡcomplete羊水专用细胞培养基可以明显提高晚期羊水间充质干细胞培养的成功率。羊水的最佳采集时间为15~20周。     

Urinary excretion of 4-hydroxy-3-methoxyphenylglycol and 4-hydroxy-3-methoxyphenylethanol in man and rat

A sensitive, reproducible, and specific gas Chromatographic method for the assay of urinary excretion of free and conjugated 4-hydroxy-3-methoxyphenylglycol (HMPG) and 4-hydroxy-3-methoxyphenylethanol (HMPE) is described. These metabolites are derivatized by reacting them with pentafluoropropionic anhydride. Quantification of these derivatives emerging from the Chromatographic column was by electron capture detection (GC/ECD) and by mass fragmentography. Mean and standard error of metabolites excreted from 9 men and 5 male rats are given. Results are expressed as excretion per day or against creatinine. Since the HMPE and HMPG were also found in the urine of rats fed on an artificial casein diet it is suggested that they are produced endogenously.     

足月妊娠羊水超声组织定征及临床应用价值研究

目的：对足月孕妇羊水进行超声回声强度（EI）定量分析，为临床及时诊断胎儿宫内窘迫提供客观的羊水性状指标。方法：对27例足月妊娠孕妇羊水池进行EI定量测定。根据手术分娩后羊水性状分为正常羊水组（16例）及羊水粪染组（11例），比较两组间EI灰阶（GS）、分贝（dB）差异。结果：羊水粪染组灰阶及分贝最大值明显高于正常羊水组。结论：超声组织定征可用于临床前羊水性状的监测。     

Stable isotope dilution analysis of orotic acid and uracil in amniotic fluid

Rapid, sensitive and accurate stable isotope dilution assays were developed for the measurement of orotic acid and uracil in amniotic fluid. The method utilizes [15N2]orotic acid and [15N2]uracil as internal standards, isolation by liquid partition chromatography and quantitation by chemical ionization selected ion monitoring gas chromatography-mass spectrometry. Orotic acid at a concentration of 0.26 +/- 0.05 mumol/l and uracil at a concentration of 0.55 +/- 0.13 mumol/l were detectable in normal amniotic fluid. As affected fetuses with argininosuccinate synthetase or ornithine carbamoyl transferase deficiency showed no significant elevation of orotic acid and/or uracil in their surrounding amniotic fluids, this method unfortunately seemed not to be useful for prenatal diagnosis of these inherited disorders. Nevertheless, it provides significant advantage over available methods for the quantitation of orotic acid and uracil in which the analysis of these compounds must be very accurate, highly specific and sensitive (e.g. detection of heterozygosity for ornithine carbamoyl transferase deficiency).     

Adsorption of organic acids from amniotic fluid and urine onto silica gel before analysis by gas chromatography and combined gas chromatography/mass spectrometry.

We describe a method for adsorbing organic acids from amniotic fluid and urine specimens onto a column of silica gel before analysis by gas chromatography and by combined gas chromatography/mass spectrometry. Analytical recoveries of individual organic acids by our adsorption method compare favorably with those obtained by a more laborious manual extraction with ethyl acetate. Results for specimens of amniotic fluid and urine show that our method gives better recoveries of most of the organic acids. Furthermore, because citric acid is also extracted in our method without extracting significant amounts of sulfate or phosphate, the method is a suitable alternative to methods involving the use of DEAE-Sephadex for concentrating these acids.     

The secretion of ibuprofen metabolites interferes with the capillary chromatography of urinary homovanillic acid and 4-hydroxy-3-methoxymandelic acid in neuroblastoma diagnosis.

Neuroblastoma is the most common extracranial solid tumor in children. Abnormal secretion of catecholamines in tissues and body fluids allows for the differential diagnosis of neuroblastoma from other neoplasms and its distinction from non-neoplastic inflammatory diseases. This is achieved by assaying homovanillic acid and 4-hydroxy-3-methoxymandelic acid, the catabolites of catecholamine metabolism. In the course of an evaluation of children with suspected neuroblastoma, homovanillic acid and 4-hydroxy-3-methoxymandelic acid were analyzed in urine samples by capillary gas chromatography with flame ionization detection after extraction and derivatization of these compounds as trimethylsilyl derivatives. In three urine samples a significant increase in biogenic amines was observed, but these results were not confirmed by thin-layer chromatography. Patient history revealed that these children had been treated with ibuprofen, an analgesic and anti-inflammatory drug. To verify how ibuprofen or its metabolites may have interfered with capillary gas chromatography with flame ionization detection, we analyzed the same samples by capillary gas chromatography-mass spectrometry. In urine samples from patients on the drug, the presence of a peak identified as the trimethylsilyl ester of hydroxyibuprofen, which had the same retention time as 4-hydroxy-3-methoxymandelic acid, was found to interfere with the capillary gas chromatography with flame ionization detection analysis of the metabolite. This interference must be taken into account during the laboratory diagnosis of neuroblastoma.     

Isotope dilution analysis of methylcitric acid in amniotic fluid for the prenatal diagnosis of propionic and methylmalonic acidemia

A stable isotope dilution assay for methylcitric acid in amniotic fluid was developed to provide rapid prenatal diagnosis of the inherited disorders propionic acidemia and methylmalonic acidemia. The method utilizes two ²H₃-labeled diastereoisomers of methylcitric acid as internal standards, isolation by liquid partition chromatography and quantitation of the trimethyl esters by chemical ionization selected ion monitoring gas chromatography-mass spectrometry. Methylcitric acid at a concentration of 0.38 ± 0.10 μmol/1 was detected in normal amniotic fluid. Highly elevated levels of 7.87 and 9.16 μmol were found in the fluids surrounding fetuses affected with propionic acidemia and levels of 1.79, 2.72 and 12.27 μmol were found for fetuses with methylmalonic acidemia. Methylcitric acid was not elevated in the amniotic fluid of a fetus heterozygous for propionic acidemia. In the five pregnancies at risk for propionic acidemia, and three pregnancies at risk for methylmalonic acidemia, the levels of methylcitric acid in amniotic fluid gave the diagnosis in all cases. Measurement of methylcitric acid in amniotic fluid therefore provides a rapid and reliable method for the prenatal diagnosis of these genetic disorders.     

Quantification of 3-methylglutaconic acid in urine, plasma, and amniotic fluid by isotope-dilution gas chromatography/mass spectrometry

A method is described for quantification of the trace metabolite, 3-methylglutaconic acid, by isotope-dilution gas chromatography/mass spectrometry using synthetic 3-[2,4,6-¹³C₃] methylglutaconic acid. Results are shown for quantification of 3-methylglutaconic acid in plasma, urine, cerebrospinal fluid and amniotic fluid for both normal controls and patients with different forms of 3-methylglutaconic aciduria. A simple method for the synthesis and purification of 3-[2,4,6-¹³C₃]methylglutaconic acid is also described.     

The thromboplastic activity of lung surfactant in amniotic fluid and its application to prenatal assessment of fetal lung maturity

Based on the fact that both tissue thromboplastin and lung surfactant show lamellar structures under the electron microscope and belong chemically to lipoprotein, the thromboplastic activity of lung surfactant in amniotic fluid was studied by measuring plasma recalcification time. The results obtained were as follows (1) The surfactant fractions isolated from amniotic fluid and rabbit or pig lung showed the thromboplastic activity with dose response. (2) The thromboplastic activity of amniotic fluid increased with advancing gestational age. (3) It was found that the thromboplastic activity determined by plasma recalcification time was parallel with the surfactant concentration of amniotic fluid. (4) The shortening rate of plasma recalcification time in amniotic fluid could estimate well the risk of RDS, and the critical value for RDS was assumed to be about 33%.     

Cholesterol in amniotic fluid, determined by gas chromatography.

Cholesterol was extracted from amniotic fluid, saponified, converted to its trimethylsilyl derivative, and gas chromatographed, with cholesteryl acetate as the internal standard. The method is sufficiently accurate and precise for use with the range of concentrations of cholesterol found in amniotic fluid (5 to 48 mg/litre). Total cholesterol was measured in amniotic fluids collected at different stages of gestation. No significant trend or change was observed nor was cholesterol in the amniotic fluid and the mother's serum correlated at any stage of gestation. Thus we conclude that cholesterol is not a useful indicator of fetal age or maturity. Cholesterol concentrations in amniotic fluid from complicated pregnancies were within the range found for normal pregnancies.     

The expression of fucose isoforms of amniotic and plasma alpha-1-acid glycoprotein derived from 2nd and 3rd trimester normal pregnancies

Objectives

To analyse modifications in AGP fucosylation in relation to different stages of human pregnancy.

Design and methods

The relative amounts of three fucosyl-glycotopes on AGP were analysed by lectin-ELISA using fucose-specific biotinylated lectins in 169 plasma and 178 amniotic fluid samples from normal pregnancies with gestational ages of 14 to 42 weeks.

Results

The plasma AGPs of all the pregnant women and amniotic AGPs from the 2nd trimester lacked fucoses. In contrast, in the 3rd trimester the amniotic AGPs were highly decorated by the innermost α1,6-fucose as well as α1,2- and α1,3-fucoses of the outer arms, reaching the highest expression around the perinatal period. At delivery the relative amounts of the α1,3- and α1,2-AGP isoforms, but not the α1,6 isoform, significantly decreased.

Conclusions

The highly fucosylated amniotic AGP isoforms could be implicated in regulatory processes to ensure homeostasis during pregnancy and to protect the fetus. They have the potential of becoming laboratory markers in obstetrics to monitor pregnancy.     

The value of various investigations of amniotic fluid in the estimation of fetal maturity (author's transl)]

The amniotic fluid lecithin-spingomyelin (L/S) ratio, creatinine and uric acid concentrations, percentage of organe-stained fat cells and the foam test by Clements and coworkers have been compared in 82 samples of amniotic fluid from 66 patients. The specimens were obtained by transabdominal amniocentesis or amniotomy between the 24th and the 42nd week of pregnancy. The determination of the L/S ratio and the foam test seem to be reliable methods of estimating pulmonary surfactant and, hence, of predicting the respiratory distress syndrome (RDS) in the newborn infant. There was no RDS with an L/S ratio greater than 1.6 to 1.8. Positive foam tests also seem to be a valuable indicator of pulmonary maturity, no cases of RDS being found. However, false negative foam tests are not rare. The amniotic fluid concentration of creatinine correlated well with gestational age and birth weight. The determination of uric acid in the amniotic fluid is an unreliable test of fetal maturity on account of the large scatter. The percentage of orange-stained cells did not rise above 10% before the 39th week of pregnancy in most cases.     

Acid esterase activity in cultured skin fibroblasts and amniotic fluid cells using 4-methylumbelliferyl palmitate.

The properties and levels of acid esterase in cultured skin fibroblasts and amniotic fluid cells were investigated using 4-methylumbelliferyl palmitate as substrate. Determinations of acid esterase activity could be made using as little as 1 microgram cell protein. Cardiolipin increased the activity 2--3 fold at the pH optimum 4.0. The apparent KM for both cell types studied was 196 micrometer without and 96 micrometer with cardiolipin. Acid esterase activity was inhibited by cyanide and thiomersal, but not by iodoacetate and N-ethylmaleimide. However activation by cardiolipin was prevented by iodoacetate, N-ethylmaleimide and also sodium chloride. Skin fibroblasts and primary amniotic fluid cells had similar levels with or without cardiolipin. A cyclic activity was found with subculture but no consistent pattern with passage. The acid esterase deficiency in Wolman's and cholesterol ester storage diseases was demonstrated with this substrate.     

Microdetermination of methylmalonic acid and other short chain dicarboxylic acids by gas chromatography: use in prenatal diagnosis of methylmalonic acidemia and in studies of isovaleric acidemia.

We have developed a sensitive gas-chromatographic method for the determination of methylmalonic acid and other short chain dircarboxylic acids in biological samples. The method is based on the isolation of the short chain dicarboxylic acid fraction by Dowex 3 X 4 column chromatography followed by gas-chromatography analysis of these acids as methyl esters. 2-n-Pentyl-malonic acid is used as an internal standard. With this method, methylmalonic, succinic and methylsuccinic acids were consistently detected and accurately measured in urine and serum from normal subjects; the identity of these acids being verified by mass spectroscopy. The method's sensitivity permitted its used in the prenatal diagnosis of methylmalonic acidemia by measuring methylmalonic acid in urine and amniotic fluid from three pregnant heterozygous women at risk. One affected (vitamin B-12 responsive type) and two unaffected fetuses were correctly diagnosed prenatally as judged by postnatal investigations. The amount of methylmalonic acid in urine and amniotic fluid was distinctly increased (2 to 14 times normal) in the former and consistently normal in the latter two cases during the third trimester of pregnancy. Effect of prenatal therapy with large doses of vitamin B-12 was closely followed in the first case using analyses of multiple maternal urine specimens. Urinary methylsuccinic acid excretion was studied in two cases with isovaleric acidemia. It was normal in a sample from a patient in remission but was increased seven fold over control during an episode of ketoacidosis.     

Interconversion of O-methylated norepinephrine metabolites in humans

Levo-norepinephrine labeled with tritium was used to study urinary norepinephrine metabolites as an index of whole body norepinephrine turnover. Six healthy volunteers were given intravenous infusions of [ring-2,5,6-3H] levo-norepinephrine, followed by collection of urine for 24 hours. Specific activities were determined by high-performance liquid chromatography for each of the three O-methylated metabolites of norepinephrine in the urine samples, and were then used to calculate the fraction of 4-hydroxy-3-methoxymandelic acid (VMA) formed from 4-hydroxy-3-methoxyphenylglycol (MHPG) and from normetanephrine. These values were used, in conjunction with total excretion of each of these metabolites, to calculate the fraction of MHPG and normetanephrine converted to VMA. The fraction of VMA formed from MHPG was 0.821 +/- 0.020, and that from normetanephrine was 0.179 +/- 0.020. Whereas fractional conversion of normetanephrine to VMA was 0.634 +/- 0.030, that of MHPG to VMA was only 0.507 +/- 0.025. Similar results were obtained when the experiment was repeated in three of the subjects using [8-14C] levo-norepinephrine, suggesting that isotope, specific activity, and position of the label were not determinants of the values obtained. The present results confirm the extent of conversion of MHPG to VMA described by others, and suggest that a higher percentage of normetanephrine than previously reported is converted to VMA.     

Correlation between fetal gastric size and amniotic fluid volume

PURPOSE: Since abnormal conditions of the fetal digestive tract may alter both amniotic fluid volume and fetal gastric volume, we sought to determine whether amniotic fluid volume is correlated with fetal gastric volume in normal pregnancy. METHODS: A total of 280 fetal gastric size measurements were made prospectively from routine sonographic examinations of women with normal singleton pregnancies between 16 and 42 weeks of gestation. The fetal stomach was defined as the largest area including the pyloric site on transverse or oblique real-time sonographic scans. Gastric volume was calculated according to the formula for a prolate ellipsoid. The amniotic fluid index (AFI) was used for the evaluation of amniotic fluid volume. RESULTS: Both fetal gastric volume and AFI were significantly correlated with gestational age (R2= 0.422 and R2= 0.128, respectively). Only a weak correlation was found between gastric volume and AFI (R2= 0.036, p <0.001). On multivariate linear regression analysis adjusting for gestational age and fetal biometric measurements, gastric volume was not an independent and significant predictor of AFI. CONCLUSIONS: Although sonographically determined fetal gastric volume measurements appear to be useful in the assessment of fetal digestive tract anomalies, fetal gastric volume has no clinically significant effect on the amniotic fluid volume in normal pregnancy.     

Catalytic ferrous iron in amniotic fluid as a predictive marker of human maternal-fetal disorders

Amniotic fluid contains numerous biomolecules derived from fetus and mother, thus providing precious information on pregnancy. Here, we evaluated oxidative stress of human amniotic fluid and measured the concentration of catalytic Fe(II). Amniotic fluid samples were collected with consent from a total of 89 subjects in Nagoya University Hospital, under necessary medical interventions: normal pregnancy at term, normal pregnancy at the 2nd trimester, preterm delivery with maternal disorders but without fetal disorders, congenital diaphragmatic hernia, fetal growth restriction, pregnancy-induced hypertension, gestational diabetes mellitus, Down syndrome and trisomy 18. Catalytic Fe(II) and oxidative stress markers (8-hydroxy-2''-deoxyguanosine, 8-OHdG; dityrosine) were determined with RhoNox-1 and specific antibodies, respectively, using plate assays. Levels of 8-OHdG and dityrosine were higher in the 3rd trimester compared with the 2nd trimester in normal subjects, and the abnormal groups generally showed lower levels than the controls, thus suggesting that they represent fetal metabolic activities. In contrast, catalytic Fe(II) was higher in the 2nd trimester than the 3rd trimester in the normal subjects, and overall the abnormal groups showed higher levels than the controls, suggesting that high catalytic Fe(II) at late gestation reflects fetal pathologic alterations. Notably, products of H₂O₂ and catalytic Fe(II) remained almost constant in amniotic fluid.