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Biomedical subjects

T Joh

Publications and source records attributed to T Joh.

At least 109 records · Page 6Linked to original sources
PubMed1994

Role of myosin light-chain kinase and protein kinase C in pepsinogen secretion from guinea pig gastric chief cells in monolayer culture.

We evaluated the role of myosin light-chain kinase (MLCK) and protein kinase C (PKC) in pepsinogen secretion from guinea pig gastric chief cells using a monolayer culture system of chief cells and an enzyme immunoassay system for guinea pig pepsinogen. An MLCK inhibitor, 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), significantly inhibited both the basal pepsinogen secretion and the secretion by carbamylcholine chloride (carbachol) or ionomycin without affecting intracellular free Ca2+ concentration ([Ca2+]i), but not by 12-O-tetradecanoylphorbol-13- acetate (TPA) or forskolin. A PKC inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), significantly reduced the pepsinogen secretion by carbachol or TPA, but not by forskolin or ionomycin, and did not affect the basal secretion and the [Ca2+]i elevated by carbachol or ionomycin. We concluded that: (1) MLCK plays an important role in basal and drug-stimulated pepsinogen secretion, (2) MLCK is involved in the Ca(2+)-dependent intracellular pathway but not in the cyclic adenosine monophosphate (cAMP) dependent pathway, (3) PKC is irrelevant to activation of MLCK, and (4) increases in cAMP and [Ca2+]i are independent of activation of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

A survey of genes expressed in undifferentiated mouse embryonal carcinoma F9 cells: characterization of low-abundance mRNAs.

As a first step to catalogue mRNAs present in mouse embryonal carcinoma F9 cells, 879 clones corresponding to low-abundance mRNAs were selected from among 2,896 randomly picked up clones of undifferentiated F9 cDNA libraries, using DNA probes complementary to poly(A)+RNAs prepared from undifferentiated F9 cells and to ones prepared from mouse fibroblast L cells. Five-hundred and eighty-two of the 879 clones were partially sequenced, and the subsequent homology search revealed that 201 corresponded to 180 known genes or known DNA sequences, which include not only housekeeping genes but also various tissue-specific genes. Interestingly, at least 24 of the 180 genes are development-related genes in mammals. Among these 24, those for midkine (growth and/or differentiation factor) and interferon-beta are reportedly up-regulated, and those for ECA39 (target for c-Myc regulation), REX-1 (zinc finger protein), and OCT-3 (POU-domain transcription factor) are down-regulated during the development of mouse embryonal carcinoma cells. Thirty-seven of the 582 clones matched the 36 previously reported unidentified ESTs (expressed sequence tags) and the remaining 344 corresponded to 329 novel ESTs. Therefore, partial sequencing of F9 cDNA clones corresponding to low-abundance mRNAs in F9 cells not only provides valuable information concerning development-related genes in mammals, but also many novel ESTs useful for studying mammalian genomes.

Animals↗
PubMed1994

Gastric epithelial damage induced by local ischemia-reperfusion with or without exogenous acid.

We evaluated the damage to the gastric epithelium produced by local ischemia-reperfusion (IR) with or without luminal perfusion with 0.1 N HCl. Local gastric ischemia was induced by clamping the left gastric artery. Use of radioactive microsphere technique revealed a significant reduction in blood flow induced only in the corpus (67% reduction). Because no measurable gross lesion was observed in this model, the blood-to-lumen clearance of 51Cr-labeled EDTA (51Cr-EDTA) served as an index of epithelial damage. In the absence of exogenous acid, the histological damage was minimum and could not be quantified. However, a significant increase in 51Cr-EDTA clearance was observed shortly after reperfusion in a manner that depended on the duration of ischemia. This increase in clearance reached a maximum approximately 10 min after reperfusion and returned rapidly toward control levels within 40-50 min after reperfusion. In the presence of exogenous acid, EDTA clearance increased significantly during ischemia, increased further during reperfusion, and did not recover for at least 60 min after reperfusion. The acid infused after reperfusion (no acid before reperfusion) did not significantly aggravate the mucosal damage that followed reperfusion. However, the acid infused before reperfusion (no acid after reperfusion) showed an effect on EDTA clearance similar to that induced by continuous acid perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗
PubMed1994

Schwannoma of the duodenum causing melena.

A rare case of duodenal schwannoma is reported. A 69-year-old man was admitted for evaluation of melena. Endoscopy and hypotonic duodenography showed a submucosal tumor in the third part of the duodenum. Biopsy findings were suggestive of leiomyosarcoma, therefore pancreatoduodenectomy was performed. Hematoxylin-eosin staining of the resected specimen showed interlacing bundles of spindle-shaped cells with palisading nuclei. Immunohistochemical staining showed positivity for S-100 protein and neuron-specific enolase, but desmin was negative, thus a diagnosis of schwannoma was made. Schwannoma is often difficult to distinguish from leiomyogenic tumors by standard staining, but immunohistochemical staining proved useful in this case.

Aged↗
PubMed1994

[Evaluation of the mechanism of endothelin-induced rat gastric mucosal lesion formation].

There are several reports on the gastric mucotoxic effect of endothelin (ET). The mechanism of this effect, however, remains largely unknown. To evaluate this, we assessed the gastric injury and changes in gastric mucosal blood flow induced by ET using ONO-1078, a sulfide peptide leukotriene (LT) antagonist, CV-3988, a platelet-activating factor (PAF) antagonist, and diltiazem, a Ca2+ channel blocker. In fasted and anesthetized rats, 2 nmol/kg of ET was infused for 30 min into splenic artery to deliver the drug as much as selectively to the stomach. Ninety minutes after beginning the drug infusion rats were killed and gastric mucosal damage in the removed stomachs was assessed. Gastric mucosal blood flow (GMBF) was measured for 90 min with a 30 min-interval by the laser Doppler flowmetry method. ET induced severe gastric mucosal damage, which was characterized by congestion of mucosal capillary and accompanied by significant reduction of GMBF, as compared with control. However, these mucotoxic effect of ET was significantly inhibited by 20 mg/kg of ONO-1078 given i. g. 60 min before ET infusion and i. v. administration of 10 mg/kg of CV-3988 and 1 mg/kg of diltiazem 30 min prior to ET. From these results, we conclude that PAF, LT and Ca2+ may play important pathogenetic roles as chemical mediators in the mechanism of the formation of ET-induced gastric mucosal lesions.

Animals↗
PubMed1993

Endogenous vasoconstrictor tone in intestine of normal and portal hypertensive rats.

The purpose of the present study was to determine the effects of endogenous norepinephrine, vasopressin (AVP), and angiotensin II (ANG II) on normal intestinal microvascular dimensions and to determine whether endogenous vasoconstrictor tone was altered in chronic portal hypertension. The intestine of normal and portal hypertensive rats was prepared for in vivo microscopic observation, and an arteriole (1A, 2A, or 3A) was selected for study. Arteriolar diameter and erythrocyte velocity were continuously monitored and used in the calculation of arteriolar blood flow. Once steady-state conditions were established, specific antagonists to alpha-adrenergic, AVP, or ANG II receptors were applied locally to remove the influences of each of these systems. In normal animals, blockade of alpha-adrenergic receptors produced a 1.3, 1.5, and 14.7% increase in the diameter of 1A, 2A, and 3A, respectively. AVP blockade in normal animals produced an 8.7, 1.6, and 1.5% increase in the diameter of 1A, 2A, and 3A, respectively; ANG II blockade only produced an increase in 3A diameter (5.8%). alpha-Adrenergic blockade produced a smaller increase in portal hypertensive 3A diameter (2.3%) compared with normal rats. AVP and ANG II blockade produced a significantly larger dilation of 3A (AVP, 4.8%) and 1A (ANG II, 3.8%), respectively, compared with control. Plasma AVP and ANG II levels were higher in portal hypertensive (AVP, 9.1 pg/ml; ANG II, 8.6 pg/ml) than in normal rats (AVP, 5.5 pg/ml; ANG II, 6.6 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1993

Acute myocardial infarction due to coronary embolization from left atrial myxoma.

We encountered a 67-year-old woman with a left atrial myxoma which was discovered during echocardiographic examination and emergency coronary arteriography just after an onset of acute inferior myocardial infarction. Coronary arteriography disclosed an abrupt and total occlusion of the right coronary artery and an abnormally large and tortuous atrial circumflex branch feeding a left atrial mass. These findings were the most useful for diagnosis. Aorto-coronary bypass surgery and excision of the myxoma were performed simultaneously by emergency operation. The postoperative course was uneventful. Myocardial infarction in this patient is believed to have been caused by coronary embolization from the left atrial myxoma.

Adolescent↗
PubMed1993

A case of pheochromocytoma complicated with acute renal failure and cardiomyopathy.

We encountered a case of pheochromocytoma which was characterized by the sudden onset of acute renal failure and pulmonary edema. Acute renal failure was rapidly improved after surgical removal of the tumor. This patient was also found to have a hypertrophied, dilated and hypokinetic left ventricle as assessed by echocardiography. Two years after tumor resection, cardiac size and function were normalized. This shows that a catecholamine-induced cardiomyopathy is reversible.

Acute Kidney Injury↗
PubMed1993

[The establishment of a monolayer culture system of guinea pig chief cells and an enzyme immunoassay system for guinea pig pepsinogen].

For the purpose of studying pepsinogen secretion from gastric chief cells, we established a monolayer culture system of guinea pig chief cells and an enzyme immunoassay (EIA) system specific for guinea pig pepsinogen. Dispersed chief cells were obtained from gastric mucosa of a guinea pig using collagenase, GEDTA, and Percoll solution, suspended in DMEM/F-12 (1/1 containing 10% FCS) media, and cultured for 70hr. Then the monolayer culture system was established. Pepsinogen was purified from gastric mucosa of a guinea pig using DEAE-Sephacel and Sephacryl S-200 columns. Antibody to pepsinogen was raised by immunizing rabbit with the purified pepsinogen. A two-site EIA system was then established using beta-galactosidase-labeled Fab' antibody. The EIA system showed sensitivity to measure above 1.5ng of guinea pig pepsinogen, and the monolayer culture system responded well to secretagogues. These systems are useful for studying pepsinogen secretion.

Animals↗
PubMed1992

A tissue-specific MAR/SAR DNA-binding protein with unusual binding site recognition.

A human cDNA was cloned that encodes a DNA-binding protein (SATB1) that is expressed predominantly in thymus and binds selectively to the nuclear matrix/scaffold-associating DNAs (MARs/SARs). Missing nucleoside experiments showed that SATB1 selectively binds in a special AT-rich sequence context where one strand consists of mixed A's, T's, and C's, excluding G's (ATC sequences). When this feature is destroyed by mutation, SATB1 binding is greatly reduced even if the direct contact sequence remains intact. Conjunctional SATB1-binding sequences become stably unpaired in supercoiled DNA. Specific mutations that diminish the unwinding potential greatly reduce SATB1 binding. However, SATB1 does not bind single-stranded DNA. Chemical interference assays show that SATB1 binds along the minor groove with very little contact with the bases. This suggests that SATB1 recognizes the ATC sequence indirectly through the altered sugar-phosphate backbone structure present in the double-stranded DNA.

Amino Acid Sequence↗
PubMed1992

Biological significance of unwinding capability of nuclear matrix-associating DNAs.

Matrix attachment regions (MARs) are thought to separate chromatin into topologically constrained loop domains. A MAR located 5' of the human beta-interferon gene becomes stably base-unpaired under superhelical strain, as do the MARs flanking the immunoglobulin heavy chain gene enhancer; in both cases a nucleation site exists for DNA unwinding. Concatemerized oligonucleotides containing the unwinding nucleation site exhibited a strong affinity for the nuclear scaffold and augmented SV40 promoter activity in stable transformants. Mutated concatemerized oligonucleotides resisted unwinding, showed weak affinity for the nuclear scaffold, and did not enhance promoter activity. These results suggest that the DNA feature capable of relieving superhelical strain is important for MAR functions.

Base Sequence↗
PubMed1992

Protection of gastric mucosa against ethanol-induced injury by intragastric bolus administration of epidermal growth factor combined with hydroxypropylcellulose.

Orally administered epidermal growth factor (EGF) has been shown to protect the gastric mucosa against injury induced by noxious agents. However, EGF administered by intragastric bolus appears to have less effect on the gastric mucosa because of its rapid excretion from the gastric lumen. In this study, mouse EGF given to rats by gastric intubation was confirmed to remain in the stomach at significantly high concentrations when given in combination with hydroxypropylcellulose (HPC), an agent that retards drug release. The residual mouse EGF levels in the gastric luminal content and tissue 3 h after administration of 50 micrograms/kg of EGF dissolved in 1 ml of 2% HPC were 30 and 60 times higher, respectively, than those obtained after EGF alone. Pretreatment with intragastric bolus administration of EGF and HPC at the same dose for 3 h attenuated significantly the development of gastric lesions induced by absolute ethanol compared to that with HPC alone, EGF alone, or saline (mean values of ulcer index: EGF + HPC, 14.3; HPC, 52.8; EGF, 50.7; and saline, 63.2 mm). There were no significant differences between the ulcer index in the HPC, EGF, and saline groups. The present study indicates that exogenous EGF given as an intragastric bolus protects the gastric mucosa against injury when combined with HPC, which can bind to EGF and prevent its rapid excretion from the gastric lumen.

Animals↗
PubMed1992

Role of EDRF in splanchnic blood flow of normal and chronic portal hypertensive rats.

The role of endogenous endothelium-derived relaxing factor (EDRF) in splanchnic blood flow was assessed in normal and portal vein-stenosed rats (PSRs). Specific and maximal inhibition of EDRF was achieved by intravenous administration of NG-nitro-L-arginine (L-NOARG) as a 1.75 mumol/kg bolus, followed by constant infusion of 1.75 mumol/kg for 20 min. Pretreatment with L-arginine (175 mumol/kg iv) completely blocked both hypertension and the reduction in blood flow induced by L-NOARG. Pretreatment with D-arginine (175 mumol/kg iv) and prazosin (500 micrograms/kg iv) did not attenuate the pressor effect of L-NOARG. These results indicate that L-NOARG selectively blocks EDRF. The blood flow to the stomach, duodenum, jejunum, ileum, cecum, and colon in control rats was 81.1 +/- 8.7, 199.1 +/- 21.9, 153.3 +/- 20.0, 68.6 +/- 10.6, 79.4 +/- 11.8, and 59.3 +/- 7.8 ml.min-1.100 g-1, respectively, and in PSRs was 141.4 +/- 10.8, 244.0 +/- 10.4, 208.3 +/- 9.8, 126.8 +/- 13.0, 166.9 +/- 16.5, and 94.8 +/- 4.7 ml.min-1.100 g-1, respectively. Blood flow was measured using the radioactive microsphere method. L-NOARG significantly reduced blood flow to the stomach, duodenum, jejunum, ileum, cecum, and colon in control rats by 47, 44, 48, 55, 40, and 41%, respectively, and in PSRs by 30, 27, 36, 33, 28, and 23%, respectively. The magnitude of blood flow reduction in PSRs was lower than in normal rats. These results indicate that EDRF plays an important role in control of the splanchnic circulation, but its effect on the hyperdynamic circulation observed in PSRs is insignificant.

Animals↗
PubMed1992

[Effect of proton pump inhibitor, in combination with epidermal growth factor, on the healing of chronic gastric ulcer in submandibular gland removed rats].

The effect of a proton pump inhibitor, omeprazole (OPZ), in combination with mouse epidermal growth factor (EGF), on the healing of chronic gastric ulcers induced by acetic acid in submandibular glands removed rats (SMR rat) was investigated. Four separate groups of SMR rats were orally administered 1 ml of distilled water (control), 100 mg/kg of OPZ alone (OPZ), 5 micrograms/kg of mouse EGF alone (EGF), or combination with (EGF + OPZ) twice daily. Two weeks later, ulcer areas of four groups were measured and expressed as the ulcer index (UI). The UI of the OPZ and EGF + OPZ group was significantly reduced as compared with that of the control. Furthermore, the UI of the EGF + OPZ group was significantly smaller than that of the EGF group. The present study indicates that the proton pump inhibitor promotes healing of chronic gastric ulcers in SMR rats and the effect of the proton pump inhibitor is enhanced by administration of mouse EGF.

Acetates↗
PubMed1992

[A 62-year-old survivor with Ebstein's anomaly without right ventricular failure].

A 62-year-old woman was admitted our hospital because of concussion of the brain. The level of consciousness improved within several days. Cardiac examination was performed because the patient had experienced feelings of fainting since one year previously, and heart murmur also was heard. The electrocardiogram showed WPW configuration. At the same time that she complained of feelings of fainting, the electrocardiogram showed supraventricular tachycardia. The echocardiogram showed displacement of the septal tricuspid leaflet and mild tricuspid valve, regurgitation. Cardiac catheterization was performed and, using the intracardiac electrocardiogram, we confirmed atrialized right ventricle. We diagnosed this patient as having Ebstein's anomaly with WPW syndrome. The clinical manifestations of this anomaly are quite variable, depending upon the spectrum of pathology and the presence of associated malformations. It is well documented that a considerable proportion of these patients are able to survive into adult life. However, the patient who survives into the sixth decade without a sign of heart failure is extremely rare. We speculate that this patient had not developed right ventricular failure until her 60's because she had a milder form of Ebstein's anomaly and did not have any other congenital heart disease.

Age Factors↗
PubMed1992

Regulation of epidermal growth factor receptor gene expression in murine embryonal carcinoma cells.

The protooncogene c-erbB1 [epidermal growth factor receptor (EGF-R)] is expressed in a wide variety of cell types and in most adult tissues. The precise roles of the EGF-R in vivo are largely unknown, especially their role in growth and development of embryonic tissues. We reported earlier that EGF-Rs are not expressed on the cell surface of undifferentiated embryonal carcinoma (EC) cells, but intracellular receptor protein is detectable (A. Weller, J. Meek, and E. D. Adamson, Development, 100: 351-363, 1987). We document here that in embryonal carcinoma cells, low levels of both receptor mRNA and protein are observed, but after 4 days of retinoic acid-induced differentiation, large increases are seen. Most notable is the 35-70-fold rise in the levels of EGF-R transcripts during the differentiation of P19 embryonal carcinoma cells to neural and glial cells, and this is paralleled by a 10-fold rise in protein. Measurements of the degradation rates of EGF-R mRNA and receptor protein show that both are rather stable and may partially explain the steady-state increases during differentiation. Run-on transcription assays of the EGF-R gene show very low rates of transcriptional activity at all stages: about 2-fold changes in transcription rate can be detected. It is concluded that transcriptional mechanisms may also partially account for increased levels of gene products. We hypothesize that the appearance of EGF-Rs at the cell surface leads to the slow induction of further receptor levels by EGF/transforming growth factor alpha stimulation, and this contributes to the driving force of differentiation and to the stability of the differentiated state.

Animals↗