Biomedical subjects

T Joh

Publications and source records attributed to T Joh.

At least 127 records · Page 7Linked to original sources

PubMed1991

Role of bile acids in splanchnic hemodynamic response to chronic portal hypertension.

Previous studies from our laboratory suggest that humoral factors, namely glucagon, can account for approximately 30% of the splanchnic vasodilation in rats with prehepatic portal hypertension. A reduced vascular sensitivity to norepinephrine, vasopressin, and angiotensin II may contribute to the splanchnic vasodilation. However, neither glucagon nor an altered vasoconstrictor sensitivity can fully account for the splanchnic vasodilation observed in portal hypertensive subjects. Therefore, the present study was designed to examine the role of bile acids in the splanchnic hyperemia of portal hypertension since (1) serum bile acids are elevated in portal hypertensive subjects and (2) bile acids are potent intestinal vasodilators. Prehepatic portal hypertension was induced in Sprague-Dawley rats by surgical constriction of the portal vein. Ten to 14 days after the induction of portal hypertension, the enterohepatic circulation of control and portal hypertensive rats was surgically interrupted. The animals were placed in Bollman restraint cages and allowed to recover. Eighteen to 24 hr later, the rats were anesthetized with sodium pentobarbital and regional blood flow measured with radiolabeled microspheres. Normal and portal hypertensive animals without bile fistula served as controls. Plasma bile acid levels measured by radioimmunoassay were approximately 3.8 times higher in portal hypertensive animals than in control. Bile duct cannulation effectively depleted both normal and portal hypertensive animals of their circulating bile acid pool and significantly reduced portal venous inflow in portal hypertensive but not in control rats. A role for bile acids as partial mediators of the splanchnic hyperemia of portal hypertension is suggested since bile acid depletion did not completely abolish the gastrointestinal hyperemia.

Animals↗

PubMed1991

Intestinal vascular sensitivity to vasopressin in portal hypertensive rats.

The intestinal vascular responsiveness to arginine vasopressin was evaluated in rats with chronic portal hypertension. Male Sprague-Dawley rats were made portal hypertensive by stenosis of the portal vein. Ten to twelve days after the induction of chronic portal hypertension, the responsiveness of the small intestinal circulation to cumulative doses of vasopressin was evaluated using an isolated pump-perfused small intestinal preparation. The ED50 for maximal vasoconstriction was increased twofold in portal hypertensive rats compared with control rats. To determine if the impaired responsiveness to arginine vasopressin was related to the hyperglucagonemia of chronic portal hypertension, plasma glucagon levels were elevated in normal rats to levels previously measured in portal hypertensive rats (i.e. approximately 450 pg/mL), and the dose response studies were repeated. Glucagon significantly attenuated the responsiveness of the intestinal vasculature to vasopressin. Equipotent doses of nitroprusside also attenuated intestinal vascular responsiveness to vasopressin. The results indicate that there is a reduced vascular sensitivity to vasopressin in the intestine of portal hypertensive animals and suggest that elevations in circulating vasodilators in portal hypertensive conditions may partially explain this altered vascular responsiveness.

Animals↗

PubMed1991

Intestinal microvascular responsiveness to norepinephrine in chronic portal hypertension.

Effects of chronic prehepatic portal hypertension on intestinal microvascular sensitivity to norepinephrine (NE) were studied. Normal and portal hypertensive rats were anesthetized, and the intestine was prepared for in vivo microscopic observation. The preparation was transferred to a video microscope and a first-, second-, or third-order submucosal arteriole (i.e., 1A, 2A, or 3A, respectively) selected for study. Microvascular diameter and arteriolar erythrocyte velocity were measured on-line, and arteriolar blood flow was subsequently calculated as the product of velocity and vessel cross-sectional area. Once steady-state conditions were reached, the preparation was exposed to incremental doses of NE and microvessel responses were recorded. Cumulative log dose-response curves relating the change in arteriolar blood flow and vessel diameter to NE concentration were constructed for each group of arterioles and the ED50 for maximal response obtained from each dose-response relationship. NE ED50 for 1A blood flow was significantly higher in portal hypertensive rats (2.57 +/- 0.25 microM) compared with control rats (1.48 +/- 0.19 microM). Analysis of the diameter responses of 1A, 2A, and 3A indicated that the loss of vascular NE sensitivity in chronic portal hypertension was localized to the terminal submucosal arterioles (2A and 3A). No differences in the diameter response of 1A were observed between normal and portal hypertensive rats. Separate experiments were conducted to test if glucagon, a known mediator of the hyperdynamic intestinal circulation in portal hypertension, could acutely alter NE responsiveness in normal animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

A rare case of infective aneurysm involving all three sinuses of Valsalva complicated by left single coronary artery.

Infective aneurysm showing dilatation of all three coronary sinuses of Valsalva due to infective endocarditis is extremely rare. We present the first report of such a case complicated by left single coronary artery. The patient was a 55-year-old man with a past history of untreated diabetes mellitus, cerebral infarction, aortic regurgitation and high-grade fever. He was admitted with a complaint of easy fatigability. In a treadmill exercise test, asymptomatic ischemic depression of the ST segment was observed. Two-dimensional echocardiography revealed marked dilatation of all three sinuses of Valsalva, and a mural thrombus within the dilated right sinus of Valsalva. On magnetic resonance imaging, an abnormal signal in the markedly dilated right sinus of Valsalva was revealed. Coronary arteriography showed left single coronary artery (L1 type by Sharbaugh's classification). The histopathological features of the affected aorta were thought to represent the healing stage of infective endocarditis. With regard to the myocardial ischemia in this patient, it was thought to have arisen mainly through aortic regurgitation and coronary atherosclerosis due to single coronary artery, and partly influenced by untreated diabetes mellitus.

Aneurysm, Infected↗

PubMed1991

A case of clinically diagnosed pure septal infarction.

Interventricular septal involvement in myocardial infarction is usually associated with infarction of the left ventricular anterior free wall, as the obstruction is at the major portion of the left anterior descending coronary artery. Acute myocardial infarction with obstruction only of the first septal branch is rare. We describe here a case of pure septal infarction. The case was diagnosed by emergency coronary arteriogram (CAG). Although the patient had a large first septal branch, his global left ventricular function was preserved. Abnormal findings were localized in only septal region as determined by left ventriculography (LVG), two-dimensional echocardiography (2DE), and 99mtechnetium pyrophosphate (99m Tc-PYP) and 201thallium (201Tl) myocardial scintigraphy.

Adult↗

PubMed1991

[Effects and complications of continuous hepatic arterial infusion chemotherapy using implantable reservoir for liver metastases from colorectal cancer].

Continuous arterial infusion chemotherapy using implantable reservoir was performed for unresectable liver metastases from colorectal cancer and the therapeutic effects, side effects and complications were evaluated. Eleven patients were treated with four kinds of arterial infusion courses that mainly consisted of 5-FU. The arterial infusion courses were discontinued in 2 patients because of nausea and vomiting, and in one patient because of diarrhea. The catheters were dislocated in 2 patients and another 2 developed fistulous between the hepatic artery and bile duct. Three patients developed duodenal ulcer. Serum CEA was reduced in 4 patients (36%). After all, response rate was 9% (1/11). The one-year survival rates of all cases and cases treated with more than 4 courses were 36.3% and 80.0%, respectively.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1990

Regulatory regions of the mitochondrial and cytosolic isoenzyme genes participating in the malate-aspartate shuttle.

The malate-aspartate shuttle, consisting of mitochondrial and cytosolic aspartate aminotransferase and mitochondrial and cytosolic malate dehydrogenase, is a major pathway for the transport of reducing equivalents from cytosol to mitochondria in mammals. To elucidate molecular mechanisms regulating metabolic coordination between the mitochondria and the cytosol, we analyzed the 5'-flanking regulatory regions of the complete set of mouse isoenzyme genes playing a pivotal role in the shuttle. Deletion analysis and an in vivo transfection assay, using NIH3T3 cells, revealed that all the promoter regions are located within the 300-base pair regions upstream from the initiation codon. Subsequently, DNase I footprinting analyses using NIH3T3 cell nuclear extracts led to identification of several protein binding sites within these promoter regions. A synthetic oligomer containing the consensus binding site sequence for CTF/NFI, a transcription factor for RNA polymerase II, competed for the binding of proteins to the promoter regions of cytosolic aspartate aminotransferase and mitochondrial and cytosolic malate dehydrogenase genes, but not for that of the mitochondrial aspartate amino-transferase gene. On the other hand, a synthetic oligomer containing the consensus binding site sequence for Sp1, which activates transcription from promoters containing properly positioned GC boxes, competed for protein(s) binding to the promoter region of the mitochondrial aspartate aminotransferase gene.

Animals↗

PubMed1990

Effect of epidermal growth factor in combination with sucralfate or omeprazole on the healing of chronic gastric ulcers in the rat.

Epidermal growth factor (EGF) has been shown to enhance healing of experimental gastric ulcers when given subcutaneously or orally in the drinking water. This effect of EGF occurs without reducing gastric acid secretion. On the other hand, EGF reportedly is excreted rapidly from gastric lumen when administered by intragastric bolus. This suggests that further stimulation of ulcer healing may be expected if EGF is given with an acid-suppressive agent or with an agent allowing EGF to remain in rat gastric lumen at high concentrations. In the present study, EGF administered by gastric intubation at a dose of 10 micrograms/kg, which is three times smaller than reported in previous studies, was evaluated for its effect on acetic acid-induced rat gastric ulcers in combination with sucralfate or omeprazole. Sucralfate is well known selectively to bind proteins covering the ulcer base, and omeprazole is a potent acid-suppressive agent. Prior to the study of combined EGF and sucralfate, oral sucralfate was confirmed to allow endogenous gastric EGF and mouse EGF given exogenously to remain at high concentrations in gastric contents and tissues. EGF and sucralfate (2 g/kg/day) given alone failed to stimulate ulcer healing in submandibularectomized rats (SMR rat) whose endogenous gastric EGF was depleted. However, the combination of both drugs administered at the same doses significantly accelerated ulcer healing in the SMR rat. Omeprazole (200 mg/kg/day) significantly enhanced ulcer healing regardless of removal of the submandibular glands. The combination of EGF and omeprazole further stimulated ulcer healing in the SMR rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗

PubMed1990

[Continuous hepatic arterial infusion chemotherapy using implantable reservoir in liver metastases from colorectal cancer].

Continuous hepatic arterial infusion chemotherapy using implantable reservoir was performed for liver metastases from colorectal cancer, and the therapeutic effects, side effects, and complications were evaluated. 9 patients with unresectable liver metastases were as follows, 1. Group A; 3 patients, MMC 2 mg.one shot + 5-FU 250 mg/day.continuous infusion x 14 days, and then 5-FU tablets 150 mg/day.p.o. x 14 days, 2. Group B; 4 patients, MMC 2 mg.one shot + 5-FU 500 mg/day.continuous infusion x 7 days, and then 5-FU tablets 150 mg/day.p.o. x 14 days, 3. Group C; 2 patients, 5-FU 500 mg/day.continuous infusion x 14 days, and then free from agents for 14 days. In 2 of 3 group A patients, the catheters became dislocated and one died of perforation of duodenum. In group A and group B, no severe side effects were noted. But both of group C patients showed nausea, vomiting and diarrhea. In 8 of 9 patients (89%), serum CEA level fell below the preoperative level. In 4 of 7 patients who underwent CT scan, the size of the tumor regressed. Total infused dose of 5-FU was 8.17 +/- 7.56 g in group A, 16.9 +/- 2.88 g in group B, and 21.0 +/- 9.90 g in group C on average. In 2 patients of group B, therapy was repeated seven times.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1990

Molecular structures and evolution of mouse isozyme genes functioning in the malate-aspartate shuttle.

To examine molecular mechanisms of transcription of mammalian isozyme genes functioning in the malate-aspartate shuttle and to observe structural and evolutionary relationships, we investigated gene organizations of cAspAT and mAspAT, and cMDH and mMDH, and isolated and characterized cDNAs and genomic DNAs for these isozymes in mice. The deduced amino acid sequences of mouse cAspAT and mAspAT showed about 47%, and those of mouse cMDH and mMDH, about 23% overall homology. Surprisingly, the homology between the mouse cMDH and thermophilic bacterial MDH, as well as the homology between the mouse mMDH and E. coli MDH, markedly exceeds the intraspecies sequence homology between mMDH and cMDH from mice. The first duplication of a common ancestral MDH gene should thus have occurred long before the emergence of the eukaryotic cells, and subsequently, the mammalian mMDH and E. coli MDH genes have evolved from one of the duplicates. The mammalian cMDH and Thermus flavus MDH genes have no doubt evolved from one of the other duplicates. Moreover, structural organizations of the two-pairs of isozyme genes indicated that introns antedate the divergence of these mitochondrial and cytosolic isozyme genes. The 5' ends of all four isozyme genes lacked the TATA and CAAT boxes characteristic of eukaryotic promoters but did contain G + C-rich sequences and multiple transcription-initiation sites. We found several highly conserved regions in the 5' flanking sequences between mAspAT and cAspAT, between mMDH and mAspAT, and between cMDH and cAspAT genes.

Animals↗

PubMed1990

[Evaluation of SOD activity in gastric mucosa of hemorrhagic shock rats].

UNLABELLED: Superoxide dismutase (SOD) exogenously administered has been documented to protect gastric mucosa against ischemia-reinfusion injury by scavenging oxygen radicals. However, the changes in levels of endogenous SOD in ischemic gastric mucosa are not known. To evaluate this, the present study was designed. METHODS: Fasted and anesthetized SD rats were given 0.1 N HCl i.g. and received the following procedures. Study 1: (1) Ischemia group--25 min after acid instillation, blood pressure was reduced to 20-30 mmHg for 20 min. (2) Ischemia-Reinfusion group--5 min after acid administration, rats received the same hypotension as above followed by reinfusion of shed blood for 20 min. (3) Control group-Rats were killed 45 min later without hypotension and reinfusion. Study 2: Three groups of rats treated with the same procedures as in Study 1 were given allopurinol (50 mg/kg/day) i.g. once daily for 2 days prior to the experiment. All rats were killed by exsanguination from the carotid artery to avoid as much as possible contamination of gastric mucosal samples with red blood cells rich in SOD. The supernatants of the corpus and antral mucosa homogenized were prepared for measuring their SOD activity using the nitrite method modified by Oyanagui. RESULTS: SOD activity in the gastric mucosa significantly increased in both the Ischemia (Ische.) and Ischemia-Reinfusion (I-R) groups compared to the control (Ische. vs. I-R vs. Cont'l: corpus-123.4 +/- 4.8 vs. 127.4 +/- 3.6 vs. 96.9 +/- 4.4 NU/Mg protein; antrum-71.6 +/- 2.8 vs. 81.4 +/- 6.8 vs. 62.1 +/- 3.1 NU/mg protein). No increase in SOD activity was observed in rats pretreated with allopurinol. CONCLUSION: SOD activity increases with oxyradicals generation in the rat stomach subjected to either hemorrhagic ischemia alone or hemorrhagic ischemia plus reinfusion. This also suggests that oxyradicals are generated even in the ischemic period.

Animals↗

PubMed1989

An enzyme immunoassay of slow moving protease (SMP) in human gastric mucosa.

A two-site enzyme immunoassay for slow moving protease (SMP) of human gastric mucosa has been developed. The detection limit of SMP was 50 pg/tube and the optimal assay range was 0.5 to 50 ng/tube. This assay system made it possible to measure a trace amount of gastric mucosal SMP in endoscopic biopsy-specimens. Mean gastric mucosal SMP contents of the antrum, the angles, and the distal and proximal corpuses were 4.5, 3.7, 2.6, and 2.5 micrograms/mg protein, respectively. The antral mucosa contained a larger amount of SMP than the gastric mucosa of other area. The present enzyme immunoassay system is sufficiently sensitive for the clinical study of SMP in gastrointestinal tract.

Electrophoresis, Polyacrylamide Gel↗

PubMed1989

Import and processing of precursor to mitochondrial aspartate aminotransferase. Structure-function relationships of the presequence.

The precursor protein of pig mitochondrial aspartate aminotransferase (pre-mAspAT) contains a 29-residue presequence (Joh, T., Nomiyama, H., Maeda, S., Shimada, K., and Morino, Y. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 1-5). Pre-mAspAT produced in an in vitro transcription and translation system was avidly imported into pig and rat liver mitochondria to be processed to the mature form of the enzyme. The pre-mAspAT was also processed to the mature form upon incubation with mitochondrial extracts. We synthesized precursor proteins with alterations within the presequence and compared quantitatively the effects of these mutations on the rates of both import and processing. Single and multiple substitutions of four basic residues with neutral amino acids at positions 5, 8, 18, and 28 showed that each residue contributes differentially to import and processing. Substitutions of His5 and Arg8 with glycines abolished the import activity but did not appreciably affect the rate of processing. Substitution of Arg28 with leucine at the position adjacent to the cleavage site seriously impaired the processing without appreciably affecting the rate of import. Analysis of deletions revealed that the amino-terminal region from position 2 to 8 was essential for both the import and processing. Thus the positive charges in the amino-terminal region are critical for import while the amino-terminal peptide segment and the cleavage site region appear to be requisite for recognition by a processing protease.

Amino Acid Sequence↗

PubMed1989

cDNA cloning and expression of pig cytosolic aspartate aminotransferase in Escherichia coli: amino-terminal heterogeneity of expressed products and lack of its correlation with enzyme function.

A full-length cDNA encoding the pig cytosolic aspartate aminotransferase (EC 2.6.1.1) (cAspAT) was constructed from two overlapping cDNA clones. One clone (Lm pcAAT-8) isolated from a lambda gt10 pig heart cDNA library contained a 3' untranslated sequence, a poly(A) segment, and a part of the coding region for amino acid positions 127-412. Another clone (Lm pcAAT-107) isolated from a lambda gt10 primer extension library contained the coding region for amino acid positions 1-148 and a 5' untranslated sequence. Rejoining of the cDNA inserts of the two clones and recloning into pUC18 gave rise to a cDNA covering an entire coding sequence for pig cAspAT mRNA. Insertion into pKK223-3 yielded an expression plasmid, ppcAAT200. Escherichia coli JM105 cells transfected with ppcAAT200 overproduced pig cAspAT to an extent of about 3% of the total cellular soluble proteins. The expressed product was indistinguishable from the alpha subform of cAspAT isolated from pig heart in terms of specific activity, absorption spectra, molecular size, crystalline form, and immunological reactivity with anti pig cAspAT antibody. Compared with the amino-terminal sequence (Ala-Pro-Pro-) reported for pig heart cAspAT, the recombinant pig cAspAT showed heterogeneity in the amino-terminal sequence: Ala 1 (26%), Pro2 (54%), and Pro3 (19%). Construction of a mutant cAspAT with deletion of residues 1-3 and its comparison with the wild-type enzyme revealed that loss of the three amino-terminal residues does not affect the catalytic activity and structural integrity of the enzyme.

Amino Acid Sequence↗

PubMed1989

A sensitive enzyme immunoassay system of rat epidermal growth factor in biological fluids and tissue extracts.

Rat epidermal growth factor was purified from rat submandibular glands to obtain specific antiserum for the establishment of an immunoassay system. Purified rat epidermal growth factor showed a single peak on reverse phase HPLC and a single band on sodium dodecyl sulphate polyacrylamide gel electrophoresis at mol wt 5100 in the presence of 2-mercaptoethanol and at mol wt 41,000 in the absence of 2-mercaptoethanol. Antibody against rat epidermal growth factor showed cross-reactivities with mouse and human epidermal growth factors on soft agar-double immunodiffusion test. The established sandwich enzyme immunoassay for rat epidermal growth factor had a high sensitivity (500 fg/tube), which made it possible to measure minute amounts of endogenous rat epidermal growth factor without pretreatment. Physiological concentrations of rat epidermal growth factor in rat biological fluids and tissues were determined. Species differences in physiological distributions of epidermal growth factor are discussed.

Animals↗

PubMed1989

Role of PAF in ischemia-reperfusion injury in the rat stomach.

Ischemia-reperfusion induced extensive gastric mucosal injury and an increase in chemiluminescence activity of neutrophils obtained from the portal vein in hemorrhagic shock rats. CV-3988, a selective antagonist of platelet activating factor (PAF), significantly reduced the gross and histologic gastric damage, and the increase in chemiluminescence activity of neutrophils. These results suggest that PAF generated on hypoxia might stimulate oxygen radical production by neutrophils, resulting in the occurrence of gastric injury in hemorrhagic shock rats.

Animals↗

PubMed1988

Structural organization of the mouse cytosolic malate dehydrogenase gene: comparison with that of the mouse mitochondrial malate dehydrogenase gene.

We cloned and characterized a mouse cytosolic malate dehydrogenase (cMDHase) (EC 1.1.1.37) gene, which is about 14 x 10(3) base-pairs long and is interrupted by eight introns. The 5' and 3' flanking regions and the exact sizes and boundaries of the exon blocks, including the transcription-initiation sites, were determined. The 5' end of the gene lacks the TATA and CAAT boxes characteristic of eukaryotic promoters, but contains G + C-rich sequences, one putative binding site for a cellular transcription factor, Sp1, and at least two major transcription-initiation sites. The sequences around the transcription-initiation sites are compatible with the formation of a number of potentially stable stem-loop structures. We compared structural organization of the mouse cMDHase gene with that of the previously characterized mouse mitochondrial MDHase (mMDHase) gene, and found that the conservation of intron positions spreads across much of the two genes. This result suggests that a common ancestral gene for the cytosolic MDHase and the mitochondrial MDHase was broken up by introns, before the divergence. We also compared the nucleotide sequence of the promoter region of the mouse cytosolic MDHase gene with that of the other three mouse genes coding for isoenzymes participating in the malate-aspartate shuttle, i.e. mitochondrial MDHase, cytosolic and mitochondrial aspartate aminotransferases (cAspATase and mAspATase). We found that highly conserved regions are present in the promoter region of the cAspATase gene.

Amino Acid Sequence↗

PubMed1988

Structural organization of the mouse mitochondrial malate dehydrogenase gene.

Structural organization of the mouse mitochondrial malate dehydrogenase (EC 1.1.1.37) gene was determined by analyzing a genomic DNA fragment isolated from a cosmid library. The gene is 12,000 base-pairs long and contains nine exons interrupted by eight introns of various sizes. The 5' and 3'-flanking regions, and the exact sizes and boundaries of the exon blocks including the transcription-initiation sites were determined. In the 5'-flanking region, there is neither a TATA box nor a CAAT box. Instead of these sequences, there are six copies of the GGGCGG or CCGCCC sequence, which is a potential binding site for the transcription factor, Sp1. The 5'-flanking region up to about 600 nucleotides is G + C-rich (65%) and contains sequences compatible with the formation of a number of potentially stable stem-loop structures. S1 nuclease mapping and primer extension analysis demonstrated that transcription of the mitochondrial malate dehydrogenase gene initiates at multiple sites. Comparison of the nucleotide sequence of the promoter region of the mitochondrial malate dehydrogenase gene with that of the mitochondrial aspartate aminotransferase gene, revealed that there are several highly conserved regions between these two mitochondrial enzyme genes participating in the malate-aspartate shuttle.

Amino Acid Sequence↗