Participation of cytochrome P450 in mutagenic activation of the carcinogen 3'-hydroxymethyl-N,N-dimethyl-4-aminoazobenzene and its N-demethylated compounds by rat liver

Mutagenicity of the hepatocarcinogen 3'-hydroxymethyl-N, N-dimethyl-4-aminoazobenzene (3'-CH2OH-DAB) and its N-demethylated compounds was examined. Rat-liver 9000 X g supernatant (S9) fraction was used together with Salmonella typhimurium TA98 or TA100 as a tester strain. The expression of mutagenicity of 3'-CH2OH-DAB, 3'-hydroxymethyl-N-methyl-4-aminoazobenzene (3'-CH2OH-MAB) and 3'-hydroxymethyl-4-aminoazobenzene (3'-CH2OH-AB) required the presence of both microsomes and cytosol as sources of enzymes as well as NADPH as a cofactor. 3'-CH2OH-AB showed positive mutagenicity on both strains in the presence of liver S9 from untreated rats whereas 3'-CH2OH-DAB and 3'-CH2OH-MAB were negative. The treatment of rats with polychlorinated biphenyls (PCB) or 3-methylcholanthrene (3-MC) resulted in a marked increase in the ability of S9 to activate these three compounds, whereas phenobarbital (PB) induction was not effective, except for the activation of 3'-CH2OH-AB. The mutagenic activities of the three compounds in strain TA98 were considerably decreased by adding cytochrome c to the S9 mixture, but the activation reactions were insensitive to 1-(1-naphthyl)-2-thiourea (NTU) and methimazole, high-affinity flavin-containing monooxygenase (FMO) substrates. Metyrapone and 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF-525A, potent inhibitors of cytochrome P450, had no inhibitory effect on the activation of these compounds by S9 from PCB-treated rat livers. In contrast, 7,8-benzoflavone (BF), a specific inhibitor of cytochrome P448, decreased the activities of 3'-CH2OH-DAB and 3'-CH2OH-MAB by 88 and 78%, respectively, but the inhibition was negligible for 3'-CH2OH-AB.

Mutagenic activation of selected aminoazo compounds by rat liver: evidence for a cytochrome P-448 dependent reaction

Mutagenicity of 3'-methyl-N,N-dimethyl-4-aminoazobenzene (3'-Me-DAB) and its N-demethylated products was examined using rat liver 9,000 g supernatant fraction (S-9) together with Salmonella typhimurium TA98 or TA100 as a tester strain. The expression of mutagenicity of 3'-Me-DAB required the presence of both microsomes and cytosol as sources of enzymes as well as NADPH as a cofactor. 3'-Me-DAB and its N-demethylated products showed no mutagenicity towards either strain when preincubated with S-9 from untreated rat livers. The involvement of a cytochrome P-450 species in the mutagenic activation was demonstrated with hepatic S-9 by using specific enzyme inducers and inhibitors. The treatment of rats with polychlorinated biphenyls or 3-methylcholanthrene resulted in a marked increase in the ability of S-9 to activate these compounds, whereas phenobarbital induction was not effective. All the mutagenic activities were considerably decreased by adding cytochrome c to the S-9 mixture, but the activation was insensitive to 1-(1-naphthyl)-2-thiourea and methimazole, high-affinity flavin-containing monooxygenase substrates. Carbon monoxide, metyrapone, and 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride, potent cytochrome P-450 inhibitors, had no inhibitory effect on the mutagenic activation. In contrast, 7,8-benzoflavone, a specific inhibitor of cytochrome P-448, considerably inhibited the reaction. These results suggest that cytochrome P-448 and a cytosol component are involved in the mutagenic activation of 3'-Me-DAB and its N-demethylated products.

Mutagenesis in Salmonella after metabolic activation of carcinogenic azo dyes and their isomers by liver S9 from rats, mice and hamsters

The mutagenicities of 3'-methyl-N,N-dimethyl-4-aminoazobenzene (3'-Me-DAB) and 3'-CH2OH-DAB, potent hepatocarcinogens, activated by rat-liver S9 were compared with those of their isomers (2'- or 4'-substituted DAB) and with those obtained with liver S9 from mice, hamsters and man. All 6 aminoazo dyes showed positive mutagenicity on both strains TA98 and TA100 in the presence of liver S9 from rats pretreated with polychlorinated biphenyls (PCB) whereas 3'-Me-DAB and 3'-CH2OH-DAB were negative in the presence of S9 from other organs of rats and human liver. 3'-Me-DAB and 3'-CH2OH-DAB also showed negative or only a weak mutagenicity in the presence of liver S9 from non-treated animals. Treatment of the muta-carcinogens by liver S9 from PCB-treated mice or hamsters exerted mutagenicity on TA98, but less than that seen with rat-liver S9. The activity of 3'-Me-DAB in the presence of female rat-liver S9 was lower than that obtained with the male. Thus a specificity in the aminoazo dye carcinogenesis in regard to species, sex and organ was also observed in the mutagenic effects of 3'-Me-DAB on Salmonella.

Mutagenicity of N-nitrosobis(2-hydroxypropyl)amine and its related compounds in the presence of rat lung and liver S9

The mutagenic activities of N-nitrosobis(2-hydroxypropyl)amine (BHP) and its related compounds were studied in Salmonella typhimurium TA100 and TA98 strains by Ames's liquid incubation assay in the presence or absence of lung and liver S9 of rats treated with polychlorinated biphenyl (PCB). BHP and its related compounds, N-nitroso-(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), N-nitrosobis(2-oxopropyl)amine (BOP), N-nitrosobis(2-acetoxypropyl)amine (BAP), and N-nitroso-2,6-dimethylmorpholine (NDMM) showed negative mutagenicity in the absence of lung and liver S9 in TA100 and TA98 strains while those compounds showed positive in the presence of liver S9 in TA100 strain. HPOP and BOP showed positive mutagenic activity in the presence of lung S9 in TA100 strain. HPOP showed the strongest mutagenic activity in the presence of lung and liver S9.

Ischemic change of organic acids in kidney

Organic acids in rabbit renal tissue biopsy were analyzed by capillary column gas chromatography--mas s spectrometry. The change of these organic acids under ischemic conditions was determined over 60 min after clamping the renal artery and vein. The results showed that lactic acid, glycolic acid, 2-hydroxybutyric acid, 3-hydroxypropionic acid, 2-methyl-glyceric acid, glyceric acid and malic acid increased at 4 and 6 min after clamping, but then decreased at 15 min. Glycerol increased 2 min after clamping and then decreased. However, 3-deoxyaldonic acids of 3-deoxytetronic acid, 3-deoxy-2-C-hydroxymethyltetronic acid and 3-deoxypentonic acid decreased in the renal tissue biopsy from 2 min after clamping.

Discovery, isolation and structure of novel cephamycins of Streptomyces chartreusis

By the use of HPLC technique after treatment with beta-lactamases, two novel cephamycins, SF-1623 and SF-1623B, were discovered and isolated from the fermentation broth of Streptomyces chartreusis SF-1623. The structures of SF-1623 and SF-1623B were determined to contain 3-sulfothiomethyl and 3-hydroxymethyl groups respectively, by chemical and enzymatic transformation reactions. Studies on the fermentation condition and process for the large scale preparation of antibiotic SF-1623 are also described.

Amine metabolite profile of normal and uremic urine using gas chromatography--mass spectrometry

A method for the simultaneous analysis of phenolic amines and aliphatic amines in human urine is described. The amine metabolites in urine were extracted using Dowex 50W-X8 cationic resin, derivatized and analyzed by a gas chromatographic--mass spectrometric--computer system. The amine metabolites profile of 5 ml of urine was obtained with good gas chromatographic separation. The gas chromatographic method described here separates urinary phenolic amines, di- and polyamines and methylguanidine in a single chromatographic separation. The urinary levels of methylguanidine, putrescine, cadaverine, spermidine, p-tyramine, dopamine, and 3-methoxytyramine were quantitated by using a mass spectrometric technique. In uremic patients, only the urinary excretion of methylguanidine was increased in comparison with normal subjects, although the urinary excretion of other amines was decreased in uremic patients.

Metabolic activation of 2-amino-9H-pyrido[2,3-b]indole by rat-liver microsomes

Microsomal activation was required for the expression of the mutagenicity of 2-amino-9H-pyrido[2,3-b]indole (A alpha C) toward Salmonella typhimurium TA98. Pretreatment of rats with PCB, 3-methylcholanthrene or phenobarbital increased the mutagenic activating ability of hepatic microsomes by 16-, 10- and 2-fold, respectively, as compared with the untreated. The mutagenic activation of A alpha C by microsomes from PCB-treated rats was inhibited by ellipticine and alpha-naphthoflavone, whereas SKF 525-A and metyrapone showed a slight or no inhibitory effect, indicating that the P-448 form of cytochrome P-450 is involved in the mutagenic activation of A alpha C. Metabolic activation of A alpha C was studied by a high-performance liquid chromatography and Salmonella/microsome assay system, and the mutagenic metabolites formed were determined to be the N-hydroxy and nitroso derivatives, from the results of reaction with oxidizing or reducing agents. These results strongly indicate that N-hydroxylation of A alpha C by the P-448 type of cytochrome P-450 is essential for the mutagenic activation.

Gonyautoxin associated with RNA-containing fraction in the toxic scallop digestive gland

A nontoxic high molecular substance associated with some paralytic shellfish poisons was separated by Sephadex G-50 gel filtration from the toxic digestive glands of the scallop Patinopecten yessoensis fed the causative plankton Protogonyaulax tamarensis. Unlike the corresponding fraction from the nontoxic digestive glands, the substance released gonyautoxins II and III on digestion with RNase T2, suggesting that it is associated with an RNA of P. tamarensis. It is possible that the toxification of scallop is partly due to the toxins already accumulated in Protogonyaulax cells, and partly due to incorporation of this precursor, which releases the toxins as a result of enzymic processes in the shellfish.

Gas chromatographic-mass spectrometric analysis of organic acids in renal tissue biopsy: identification of 4-hydroxybutyric acid and 4-hydroxy-2-butenoic acid

The organic acids in renal tissue biopsy (0.5-1 mg) obtained from chronic glomerulonephritis patients were analyzed capillary column gas chromatography--mass spectrometry. Some twenty compounds were identified in the renal tissue. The organic acid profile of renal tissue showed a marked difference from those of urine and serum. In particular, 4-hydroxybutyric acid and 4-hydroxy-2-butenoic acid, which are usually undetectable in urine and serum, were detected for the first time in renal tissue in considerably large amounts.

Preparation and antigenic properties of estriol 16-glucuronide- and estradiol 17-glucuronide-[C-6]-bovine serum albumin conjugates

The preparation and antigenic properties of estriol 16-glucuronide-bovine serum albumin (BSA) and estradiol 17-glucuronide-BSA conjugates in which the hapten molecule is linked to the carrier protein through an (O-carboxymethyl)oxime bridge at the C-6 position on the steroid nucleus, have been described. Antibodies raised against the two immunogens in the rabbit possessed excellent specificity to estriol 16-glucuronide and estradiol 17-glucuronide, respectively, exhibiting no significant cross-reactions with estrogen glucuronides having a substituent in ring A and no cross-reactivities with free estrogens, their sulfates and related steroids.

Identification of 2-hydroxy-2-methyllevulinic acid in urine and serum of diabetic patients with ketoacidosis

A new organic acid, 2-hydroxy-2-methyllevulinic acid, was identified in the urine of four diabetic patients with ketoacidosis using gas chromatography-mass spectrometry. The compound was also detected in two serum samples of the four patients. The compound became undetectable in the urine of the patients after insulin therapy and was not detected in urine and serum of healthy subjects or diabetic patients without ketosis. 2-Hydroxy-2-methyllevulinic acid was also detectable in the urine of a child with elevated blood lactate and pyruvate, and ketosis. This finding suggests that the occurrence of 2-hydroxy-2-methyllevulinic acid is not specific to "diabetic" ketosis but is correlated to ketosis itself.

Gas chromatographic-mass spectrometric analysis of amine metabolites in urine

An analytical method for the separation and identification of amine metabolites in human urine has been developed using a gas chromatograph-mass spectrometer-computer system. The sample preparation consists of organic solvent extraction, adsorption on a cation-exchange resin, evaporation, and acylation. N-3-Hydroxypropyl-1, 4-diaminobutane was identified for the first time in urine. Methylguanidine, guanidine, putrescine, cadaverine, p-tyramine, 3-methoxytyramine, spermidine, and spermine were detected in normal urine with good gas chromatographic separation.

Gas chromatographic-mass spectrometric profile of organic acids in urine and serum of diabetic ketotic patients

The organic acids in the urine and serum of diabetic patients with ketoacidosis and disturbance of consciousness were studied using acidification, extraction, evaporation, methoxime formation and trimethylsilylation, gas chromatographic separation and mass spectrometric identification procedures. The organic acid profile of 1 ml of serum ultrafiltrate was obtained with good separation using a gas chromatograph equipped with a glass capillary column and a splitless injector. 5-Hydroxyhexanoic acid and 3-hydroxyvaleric acid were identified for the first time in the urine of diabetic patients with ketoacidosis. Urinary excretion and serum concentrations of 2,3-dideoxypentonic acid were increased in diabetic patients.

Echocardiographic and morphological features of the pulmonic valve in patients with primary pulmonary hypertension and those with secondary pulmonary hypertension resulting from left-to-right shunt

In 11 patients with primary pulmonary hypertension (PPH) and 16 with secondary pulmonary hypertension due to left-to-right shunt (SPH), echocardiographic and morphological features of the pulmonic valve were studied. Mean ages of these patients were 27 and 31 years, respectively. The echo intensity of the pulmonic leaflet was graded as either "strong" or "not strong" by comparison with the adjacent tissue. In the PPH group, the valve echo was "not strong", while it was "strong" in the majority of the cases of SPH. In autopsy, there were no morphological changes in the pulmonic valves in the former, while these valves were definitely hypertrophic in the latter. The average thicknesses of the valve edges in the two groups of patients were 0.5 and 1.6 mm, respectively. The results suggest that the different echo intensities reflect the morphological differences of the pulmonic valve; and this provides a diagnostic value for differentiating the two conditions.

A gas chromatographic-mass spectrometric analysis for phenols in uremic serum

(1) The concentrations of unconjugated and conjugated phenol, p-cresol, benzyl alcohol, catechol, hydroquinone, homocatechol, and 2-methoxyresorcinol in uremic serum were determined using a mass fragmentographic method. Concentrations of all phenols in uremic serum were higher than in normal serum. Conjugated phenols existed mainly as sulfate esters. (2) The concentration of unconjugated phenol in uremic serum correlated with those of serum creatinine and urea, but not with the hematocrit value. Patients with the highest concentration of unconjugated phenol suffered from cerebral disorders, coma or lethargy, and hemorrhagic tendencies. Unconjugated phenol was detected in normal serum at a concentration of 0.86 +/- 0.63 mumol/l (mean +/- S.D., n = 10). (3) The concentration of unconjugated p-cresol in uremic serum did not correlate with those of serum creatinine, urea and the hematocrit value. (4) The concentrations of unconjugated and conjugated hydroquinone in uremic serum correlated with those of serum creatinine and urea. (5) 2-Methoxyresorcinol was first detected mainly as sulfate ester in uremic serum at a concentration of 19 +/- 9.0 mumol/l (mean +/- S.D,. n = 17). (6) The daily excretion of eight unconjugated phenols into normal urine was determined.

Tumorigenicity of 3'-hydroxymethyl, 3'-formyl, and 3'-carboxy derivatives of 4-(dimethylamino)azobenzene in rat liver

Male Sprague-Dawley rats were fed a cube diet containing 2.51 mmol/kg of 3'-methyl-4-(dimethylamino)azobenzene (3'-Me-DAB), 3'-CH2OH-DAB, 3'-CHO-DAB, or 3'-COOH-DAB (at a level equivalent to 0.06% 3'-Me-DAB in the diet) for a period of 1 to 3 months. Almost all the livers of rats given 3'-CH2OH-DAB for a period of 2 to 3 months or 3'-Me-DAB for 3 months showed marked cirrhosis macroscopically. The common histological findings were cholangiofibrosis with or without markedly atypical bile ducts. Moreover, one hepatocellular carcinoma was found in the liver of a rat given 3'-Me-DAB and one in the liver of a rat given 3'-CH2OH-DAB for 3 months. On the other hand, 3'CHO-DAB and 3'-COOH-DAB did not induce these changes (including neoplastic nodules) at all. Consequently, 3'-CH2OH-DAB, like 3'-Me-DAB, was found to be a hepatocarcinogen.

Syntheses of deuterated 3'-hydroxymethyl-4-(dimethylamino)-azobenzene and related compound

3'-Hydroxymethyl-4-(dimethylamino) azobenzene (I), a new potent hepatocarcinogen, and 3,3'-bis(hydroxymethyl) azobenzene (II) were labeled with multiple-deuterium for the purpose of investigating their metabolisms by the ion cluster technique. I-d4 was obtained in a 22% yield from benzoic-d5 acid (99 atom % D) by nitration, catalytic hydrogenation, reduction, and coupling of the diazonium salt with N,N-dimethylaniline and its deuterium content was 99 atom%. On the other hand, II-d8 was obtained in a 7% yield from 3-nitrobenzoic-d4 acid by reduction and was 91 atom% D.

Identification of some abnormal metabolites in psoriatic nail using gas chromatography--mass spectrometry

A gas chromatographic--mass spectrometric analysis was used to separate and identify abnormal compounds in the nail of psoriatic patients. The nail was extracted with heated ethanol, and the extract was analyzed with and without trimethylsilylation. Tetradecanoic acid octadecyl ester, hexadecanoic acid octadecyl ester and octadecanoic acid octadecyl ester were first identified in the psoriatic nail, but were not detected in normal nail.

Profiling of uremic ultrafiltrate using high resolution gas chromatography-mass spectrometry - identification of 6 polyphenols

An analytical method for separation and identification of compounds in uremic ultrafiltrate has been developed using a glass capillary column gas chromatography-mass spectrometry-computer system. The ultrafiltrate samples of blood were obtained during hemodialysis treatment of chronic uremic patients and non-uremic patients using the extracorporeal ultrafiltration method. Sample preparation consisted of acidification, extraction, evaporation, and trimethylsilylation. Many compounds were newly identified in the uremic ultrafiltrate by electron impact ionization, chemical ionization, and high resolution mass spectrometry. Six toxic polyphenols, namely, catechol, resorcinol, hydroquinone, 2-methoxyresorcinol, 3-methoxycatechol, and methoxyhydroquinone were first detected in the uremic ultrafiltrate.

Acute and chronic cardiocirculatory effects of oral prazosin in chronic refractory heart failure

The acute hemodynamic effects of oral prazosin were investigated in 7 patients with chronic refractory heart failure. A single dose of 1 to 3 mg prazosin produced a significant increase in cardiac index (+17.6%, p less than 0.01) associated with substantial decreases in pulmonary arterial diastolic pressure (-31.6%, p less than 0.02), systemic vascular resistance (-29.7%, p less than 0.01), and double product (-24.1%, p less than 0.02). Plasma renin activity was significantly elevated (+42.4%, p less than 0.02). These effects were found maximum at 2 hours and persisted for 8 hours. The chronic hemodynamic effects in 5 patients with chronic refractory heart failure were evaluated by administration of 1 to 2 mg prazosin 3 times daily for 8 weeks, and ventricular function was assessed by echocardiography and carotid pulse recording. All the patients showed improvement in the clinical symptoms of heart failure. Peripheral venous pressure decreased slightly (-12.5%). ET/PEP increased (+24.5%) without any significant changes in EF and mVcf. Plasma renin activity also slightly increased (+17.8%). Thus, prazosin possesses sustained nitroprusside-like actions, and is effective in the management of chronic congestive heart failure refractory to conventional therapy. While, further investigation is necessary to define the effect of prazosin on plasma renin activity.

Gas chromatographic-mass spectrometric identification of isosaccharino-1,4-lactone in human serum and urine

We have identified alpha-isosaccharino-1,4-lactone and beta-isosaccharino-1,4-lactone in the ethyl acetate extract of an ultrafiltrate of blood and of normal human urine, using high-resolution gas chromatography-mass spectrometry. The ultrafiltrate of blood was obtained from three patients on hemodialysis, one with psoriasis vulgaris, one with uremia, and one with amyotrophic lateral sclerosis. The concentration of beta-isosaccharino-1,4-lactone in the ultrafiltrate was two- to threefold that of alpha-isosaccharino-1,4-lactone. Mass fragmentography showed that isosaccharino-1,4-lactone is normally present in human serum in a concentration of 1.7 (SD 1.5) mg/L. In physiological fluid, isosaccharino-1,4-lactone apparently is present in its hydrated form, isosaccharinate.

Gas chromatographic-mass spectrometric identification of isosaccharino-1,4-lactone in human serum and urine

We have identified alpha-isosaccharino-1,4-lactone and beta-isosaccharino-1,4-lactone in the ethyl acetate extract of an ultrafiltrate of blood and of normal human urine, using high-resolution gas chromatography-mass spectrometry. The ultrafiltrate of blood was obtained from three patients on hemodialysis, one with psoriasis vulgaris, one with uremia, and one with amyotrophic lateral sclerosis. The concentration of beta-isosaccharino-1,4-lactone in the ultrafiltrate was two- to threefold that of alpha-isosaccharino-1,4-lactone. Mass fragmentography showed that isosaccharino-1,4-lactone is normally present in human serum in a concentration of 1.7 (SD 1.5) mg/L. In physiological fluid, isosaccharino-1,4-lactone apparently is present in its hydrated form, isosaccharinate.

Studies on a new aminoglycoside antibiotic, dactimicin. I. Producing organism and fermentation

The producing organism of a new antibiotic, dactimicin, is described. The presence of finger-shaped sporangia bearing motile spores, the absence of aerial mycelium and its cell wall of type II, ascribe this organism to the genus Dactylosporangium. The cultural and physiological features distinguish this organism from all the described Dactylosporangium species. Therefore, it is considered to be a new species for which the name Dactylosporangium matsuzakiense sp. nov. is proposed. Fermentation of dactimicin is also described.

Tryptophan and indolic tryptophan metabolites in chronic renal failure

Tryptophan and indolic tryptophan metabolites were measured in the serum of normal subjects and chronic renal failure patients. The tryptophan free/total ratio was 0.07 in the normal serum, but the other tryptophan metabolite values were below detectable levels. The free/total ratio was 0.66 in patients with chronic renal failure, and both increase of free tryptophan and decrease of total tryptophan were observed. At the same time, 5-hydroxyindoleacetic acid, indole acetic acid, 5-hydroxytryptophol, and N-acetyltryptophan also increased in the serum of chronic renal failure patients, existing not only in free form but in protein-bound form. In the serum samples, following hemodialysis the indolic tryptophan metabolites showed a tendency to decrease, and the tryptophan free/total ratio of 0.42 a approached the normal value. When indolic tryptophan metabolites were added to normal serum in vitro, the free tryptophan level rose, and competition for binding to albumin between tryptophan and indolic tryptophan metabolites was observed. These findings suggested that the cause of the decrease in protein-bound tryptophan in uremic serum may be an accumulation of indolic tryptophan metabolites which complete for binding to albumin in uremia.

Carcinogenicity of 3'-hydroxymethyl-N,N-dimethyl-4-aminoazobenzene in rat liver

Male Sprague-Dawley rats were fed a cube diet containing 2.51 mmol/kg 3'-hydroxymethyl-N,N-dimethyl-4-aminoazobenzene (3'-CH2OH-DAB) for a period of 1 or 3 months. (This is the molar equivalent of 0.06% 3'-Me-DAB in the diet). The oral administration of 3'-CH2OH-DAB for 3 months resulted in a high incidence of liver tumors at 6 months and the 1 month feeding also caused the development of liver tumors. Histologically, the tumors were cholangiocellular carcinomas and hepatocellular carcinomas. The development of tumors in other sites was not seen. Consequently, 3'-CH2OH-DAB, a recently identified metabolite of 3'-Me-DAB, is a potent hepatocarcinogen.

Hemodiafiltration with sodium concentration-controlled dialysate

When hemofiltration and hemodialysis are compared, the former is more effective in removing larger substances, whereas the latter is superior in removing small substances. We consider hemodiafiltration, in which the advantages of the two treatment methods can be adopted, as the most effective and practical method. In the studies of hemodiafiltration, we demonstrated that disequilibrium syndrome associated with the treatment can be prevented by employing a high sodium concentration in the dialysate. The dialysate was successfully used for treating intracellular overhydration. However, it could not be used without causing adverse effects such as thirst in patients whose intracellular overhydration had already been treated and resulted in increase in their body weight. However, these patients were treated successfully by decreasing the high sodium concentration gradually or in a stepwise manner.

Pattern of aliphatic dicarboxylic acids in uremic serum including a new organic acid, 2,4-dimethyladipic acid

(1) 2,4-Dimethyladipic acid was first identified in normal human urine using gas chromatography-mass spectrometry. Urinary excretion of 2,4-dimethyladipic acid in 7 healthy adults ranged from 4.9 mumol to 14 mumol per 24 h. (2) Succinic acid, adipic acid, 3-methyladipic acid, 2,4-dimethyladipic acid, pimelic acid and azelaic acid were identified in the ultrafiltrate of the blood obtained from a chronic uremic patient using a hemodialyzer. (3) Levels of succinic acid, adipic acid, 3-methyladipic acid, 2,4-dimethyladipic acid, pimelic acid and azelaic acid in uremic serum were determined using a mass fragmentographic technique. Concentration of succinic acid in uremic serum was comparable to that in normal serum, whereas concentrations of adipic acid, 3-methyladipic acid, 2,4-dimethyladipic acid, pimelic acid and azelaic acid were highly elevated in uremic serum.

Problems with activated charcoal and alumina as sorbents for medical use

Although activated charcoal and alumina have been used extensively as sorbents in uremic patients, the following problems remain to be solved: 1) elution of SO4--from activated charcoal which does not adsorb it; 2) production of methylguanidine from creatinine on the surface of activated charcoal; 3) production of lipoperoxide from fatty acids by chemical reaction of activated charcoal; 4) adsorption of Ca++ and Mg++ when alumina adsorbs inorganic phosphate. These problems are studied in vitro and clinically.

A gas chromatographic-mass spectrometric assay for nine hydroxyphenolic acids in uremic serum

A mass fragmentographic method for the determination of m-hydroxybenzoic acid, p-hydroxybenzoic acid, o-hydroxyphenylacetic acid, m-hydroxyphenylacetic acid, p-hydroxyphenylacetic acid, vanillic acid, p-hydroxymandelic acid, homovanillic acid and vanilmandelic acid in uremic serum is described. The hydroxyphenolic acids were extracted from one ml of serum ultrafiltrate. After trimethylsilylation, the extract was analyzed by a gas chromatograph-mass spectrometer. Concentrations of nine hydroxyphenolic acids are higher in uremic serum. In particular, p-hydroxybenzoic acid and p-hydroxyphenylacetic acid are markedly increased in uremic serum. The influence of hemodialysis on the hydroxyphenolic acids was studied by quantitating the acids before and after hemodialysis.