An inferior mesenteric-caval shunt via the internal iliac vein with portosystemic encephalopathy.

We report here a case of an unusual extrahepatic portosystemic venous shunt in a 37-year-old woman without liver cirrhosis or portal hypertension, who developed portal systemic encephalopathy. Angiography demonstrated an inferior mesenteric-caval shunt characterized by the presence of direct communication of the inferior mesenteric vein with the left internal iliac vein. After the treatment with percutaneous transcatheter embolization of the shunt via a femoral vein approach using coils, she had no episode of portal systemic encephalopathy.

Biosynthesis of pyridoxine: origin of the nitrogen atom of pyridoxine in microorganisms.

The amide nitrogen atom of glutamine was incorporated into pyridoxine in four eukaryotes, Emericella nidulans, Mucor racemosus, Neurospora crassa and Saccharomyces cerevisiae, and two prokaryotes, Staphylococcus aureus and Bacillus subtilis, but not in the following prokaryotes, Pseudomonas putida, Enterobacter aerogenes and Escherichia coli. On the other hand, the nitrogen atom of glutamate was incorporated into pyridoxine in P. putida, E. aerogenes and E. coli, but not in S. aureus and B. subtilis. These results suggest that there are at least two different biosynthetic routes for pyridoxine and the difference does not depend on prokaryotes and eukaryotes.

Biosynthesis of thiamin under anaerobic conditions in Saccharomyces cerevisiae.

We studied the biosynthetic route of thiamin in Saccharomyces cerevisiae to see whether the route differed under aerobic and anaerobic conditions. Histidine and pyridoxine are the precursors of the pyrimidine moiety of thiamin under aerobic conditions. Formate is incorporated into the pyrimidine via histidine. The incorporation of [13C]formate and [5'-(2)H2]pyridoxine into the pyrimidine was examined under anaerobic conditions. The labels from [13C]formate and [5'-(2)H2]pyridoxine were not incorporated into the pyrimidine under anaerobic conditions, indicating that the biosynthetic pathway of the pyrimidine differed from that under aerobic conditions. On the other hand, [15N]glycine was incorporated into the thiazole under both anaerobic and aerobic conditions. The biosynthetic pathway of the thiazole was therefore unaltered by the O2 concentration.

[Cystic vein: as a perfusion vein of hepatic portion-angiographical study].

In order to determine the hepatic portions by cystic vein, we carried out abdominal angiography in 153 patients. The cystic vein was recognized in eleven patients, but only in nine cystic venous flow could be measured. In this group of patients, in which the cystic venous flow was detected, hepatic angiography was performed through the right hepatic artery (RHA) in six patients, the anterior branch of RHA in one patient, and the cystic artery in two patients. Simultaneously, angiographical CT was performed in five patients. As the results, it is presumed that the cystic venous flow perfused segment 4 portal branch (P4) + segment 5 (S5) in four patients, P4 in two patients, segment 6 portal branch (P6), S5 + right portal vein (RPV) + right hepatic vein (RHV), and S5 + RHV in one patient, respectively, and we concluded that in 70% of cases cystic venous flow perfused either P4 or S5.

Pyrimidine moiety of thiamin is biosynthesized from pyridoxine and histidine in Saccharomyces cerevisiae.

The isotopes of [6-13C]- and [5'-2H2]pyridoxine were incorporated efficiently into the pyrimidine moiety of thiamin in S. cerevisiae. The mass fragmentation pattern showed that the C-6 and H-5' atoms of pyridoxine were incorporated into the C-6, and H-5' atoms of the pyrimidine, respectively. These findings, along with out previous results, show that the C-2', C-2, N-1, C-6, C-5, and C-5' unit of the pyrimidine are derived from the C-2', C-2, N-1, C-6, C-5 and C-5' unit of pyridoxine, and that pyrimidine is biosynthesized from pyridoxine and histidine.

Origin of the nitrogen atom of pyridoxine in Saccharomyces cerevisiae.

The origin of the nitrogen atom of pyridoxine was studied in Saccharomyces cerevisiae. The 15N atom of 15NH4Cl added to the growth medium as the nitrogen source was incorporated efficiently into the nitrogen atom of pyridoxine. The competitive effects of 14N-amino acids on the incorporation of 15NH4Cl were examined. Incorporation of 15N into pyridoxine was inhibited by glutamine. The label of L-[amide-15N]glutamine was incorporated effectively into pyridoxine in S. cerevisiae. On the other hand, the label from L-[amide-15N]glutamine was not incorporated into pyridoxine in Escherichia coli. These findings suggest that the biosynthetic pathway of pyridoxine in S. cerevisiae differs from that in E. coli.

Origin of the N-1, C-2 and C-2' atoms of the pyrimidine moiety of thiamin in Saccharomyces cerevisiae.

The precursor of the pyrimidine moiety of thiamin in S. cerevisiae was studied. The tracers [15N]- and [2'-13C]-pyridoxine were chemically synthesized, and incorporated efficiently into the pyrimidine. The mass fragmentation pattern showed that the nitrogen atom of pyridoxine was incorporated into the N-1 of the pyrimidine. In addition, the C-2' atom of pyridoxine was incorporated into the C-2' atom of the pyrimidine. These results and the structural resemblance between the pyrimidine and pyridoxine revealed that the C-2, C-2' and N-1 unit of the pyrimidine are derived from the C-2, C-2' and N-1 unit of pyridoxine.

Pyridoxine is a precursor of the pyrimidine moiety of thiamin in Saccharomyces cerevisiae.

We studied the origin of the N-1 atom of the pyrimidine moiety of thiamin in a eucaryote, Saccharomyces cerevisiae. The competitive effects of 14N-compounds on the incorporation of 15N-NH4Cl into the pyrimidine moiety were examined. Amino acids, the bases of nucleic acids and glucosamine did not decrease 15N incorporation, but pyridoxine did. We conclude that the N-atom of pyridoxine is the origin of the N-1 atom of the pyrimidine of thiamin synthesized by S. cerevisiae. We also suggest that the N-atom of pyridoxine is derived from glutamine.

Incorporation of histidine into the pyrimidine moiety of thiamin in Saccharomyces cerevisiae.

To investigate the incorporation of histidine into the pyrimidine moiety of thiamin in eukaryotes, Saccharomyces cerevisiae was grown in a synthetic medium in the presence of 15N- or 14C-labeled histidine. Two 15N-atoms of DL-[1,3-15N2]histidine were incorporated into the N-3 and amino-N atom at C-4 of pyrimidine. Furthermore, incorporation of the 15N-amino group of aspartate, the origin of the N-1 of histidine, into the N-3 of pyrimidine shows that N-3 and the amino-N atom at C-4 of pyrimidine are derived from N-1 and N-3 of histidine, respectively. In contrast, the 15N atom of DL-[amino-15N]histidine was not incorporated into the molecule, whereas L-[2-14C]histidine was incorporated directly into the pyrimidine. We conclude that N-1, C-2, and N-3 of histidine are the origins of the N-3, C-4, and amino-N at C-4 of the pyrimidine in thiamin synthesized by S. cerevisiae.

Participation of histidine in biosynthesis of the pyrimidine moiety of thiamin in Saccharomyces cerevisiae.

The amide nitrogen atom of glutamine is incorporated into the pyrimidine moiety of thiamin in Escherichia coli and Saccharomyces cerevisiae. However, addition of casamino acids to the medium increases incorporation of the amide nitrogen atom of glutamine in E. coli, but decreases it in S. cerevisiae. This suggests that some amino acids other than glutamine in casamino acids are more direct precursors of the pyrimidine moiety in S. cerevisiae. To determine the direct precursor, we investigated the competitive effect of 14N-amino acids on the incorporation of 15NH4Cl into the pyrimidine moiety and found that histidine decreased the incorporation of 15N. Thus, histidine was concluded to be the direct precursor of the nitrogen atom of the pyrimidine moiety of thiamin in S. cerevisiae.

The origin of the sulfur atom of thiamin.

The incorporation of the sulfur atom of 35S-labeled amino acids into thiamin in Escherichia coli and Saccharomyces cerevisiae was studied. The specific radioactivity of the S atoms was incorporated at similar levels into thiamin and cysteine residues in cell proteins. However, the specific radioactivity of the S atoms from [35S]methionine was not incorporated into thiamin but into methionine residues in cell proteins. Thus, the origin of the S atom of thiamin was established as being the S atom of cysteine. No activity from [U-14C]cysteine was recovered in thiamin, proving that the carbon skeleton of this amino acid was not utilized in synthesizing the thiazole moiety of thiamin.

Biosynthesis of thiamin. Different biosynthetic routes of the thiazole moiety of thiamin in aerobic organisms and anaerobic organisms.

The nitrogen atom of glycine was incorporated into the thiazole moiety of thiamin in the aerobic microorganisms Bacillus subtilis, Pseudomonas putida, Saccharomyces cerevisiae, Mucor racemosus, Neurospora crassa, and Emericella nidulans. It was not incorporated in the case of the facultative anaerobic microorganisms Escherichia coli and Enterobacter aerogenes, which, however, did incorporate the nitrogen atom of tyrosine. These results show that aerobic microorganisms and facultative anaerobic microorganisms have different biosynthetic pathways for the thiazole moiety of thiamin.

Biosynthesis of thiamin. Precursor of C-5, C-6, and hydroxymethyl carbon atoms of the pyrimidine moiety in a eucaryote.

We studied the incorporation of radioactive glucose into the pyrimidine moiety of thiamin in the eucaryote Candida utilis. Three carbons of glucose were incorporated into the pyrimidine, and the C-2 of glucose into the C-6 of the pyrimidine. We concluded that the C-5, -6, and hydroxymethyl carbon atoms of the pyrimidine in this eucaryote originate from the C-2, -3 and -4 of glucose via ribose.

Biosynthesis of thiamin. The precursor of the five-carbon unit of the thiazole moiety.

The precursor of the thiazole moiety of thiamin in Candida utilis was identified. Radioactive C-2, 3, 4, 5 and 6 of glucose was incorporated into C-4', 4, 5, 5' and 5" of the thiazole. This experiment shows that the precursor of the five carbon unit of thiazole is a 5-carbon compound such as ribose or ribulose derived from glucose.

Precursor of carbon atom five and hydroxymethyl carbon atom of the pyrimidine moiety of thiamin in Escherichia coli.

The pyrimidine moiety of thiamin can be synthesized in bacteria from 5-aminoimidazole ribotide (AIR), an intermediate in purine biosynthesis. To transform the imidazole ring of AIR to the pyrimidine, the bond between C-4 and C-5 of the imidazole ring should be ruptured and a two-carbon unit should be inserted. We investigated a precursor of the two-carbon unit which should be inserted to form the pyrimidine. To examine the possibility of the two-carbon compound as a precursor which is formed from a three-carbon intermediate in the glycolytic pathway and its three-carbon derivative by decarboxylation in cells, we studied the incorporation of [2-14C]glycerol, [2-14C]pyruvate, [U-14C]alanine and [3-14C]serine into the pyrimidine by Escherichia coli. Glycerol, pyruvate and alanine were not incorporated into the pyrimidine. Radioactive carbon of [3-14C]serine was incorporated into C-2 of the pyrimidine via one-carbon units pool. Then, we investigated the possibility of a ribose moiety of AIR being a precursor of the two-carbon unit. As ribose has low permeability into E. coli cells, the ribose moiety of AIR was labeled with [14C]glucose which was added to the growth medium. The results show that two radioactive carbons of [U-14C]glucose were incorporated into the pyrimidine and radioactive carbon of [6-14C]glucose was incorporated into hydroxymethyl carbon attached to C-5 of the pyrimidine. The dilution rates of the specific radioactivity of the pyrimidine from [U-14C]glucose and [6-14C]glucose well coincide with those of the ribose moiety of the nucleotide (AMP). Radioactive carbon of [1-14C]glucose was not incorporated into the pyrimidine and nucleotide. It is concluded that the two-carbon fragment derived from C-4' and C-5' of the ribose moiety of AIR can be incorporated into the pyrimidine moiety of thiamin as the precursor of C-5 and hydroxymethyl carbon.

Different biosynthetic pathways of the pyrimidine moiety of thiamin in procaryotes and eucaryotes.

[14C]Formate is incorporated into the C-2 of the pyrimidine moiety of thiamin by Escherichia coli and Salmonella typhimurium. In Saccharomyces cerevisiae, it is incorporated into C-4. Radioactive carbons of [1-14C]glycine and [2-14C]glycine are incorporated by S. typhimurium into the C-4 and C-6 of the pyrimidine, respectively, but not by S. cerevisiae. These facts suggest that procaryotes and eucaryotes have different biosynthetic pathways for pyrimidine. In this study, the procaryotes tested incorporated [14C]formate into the C-2 and the eucaryotes incorporated it into the C-4 of the pyrimidine.