PubMed Health⌕ Search

Biomedical subjects

A Tsuchida

Publications and source records attributed to A Tsuchida.

At least 73 records · Page 4Linked to original sources
PubMed1998

The establishment of a preoperative diagnosis of pancreatic carcinoma using cell specimens from pancreatic duct brushing with special attention to p53 mutations.

BACKGROUND: Previously, the authors reported that 82% of cases of pancreatic carcinoma were positive for p53 in cytologic specimens obtained by selective endoscopic pancreatic duct brushing (SEPB). However, there was an extreme discrepancy between the authors' data of p53 overexpression using cytologic specimens and other reports using surgically resected specimens. In this study, the authors demonstrate that p53 positive cells precisely reflect its gene mutations, and also establish systematic procedures for the preoperative diagnosis of patients with pancreatic carcinoma. METHODS: The authors examined 44 cases of pancreatic carcinoma, 30 cases of chronic pancreatitis, and 9 cases of papillary adenoma. In all cases, pathologic diagnosis was made by surgery or autopsy. The conventional cytology and p53 immunocytology were performed simultaneously in the cell specimens obtained by SEPB. In the cases immunostained for p53, DNA was extracted selectively from p53 immunostained cells using a light microscope. p53 mutations in exons 5 to 8 were examined by direct sequencing. RESULTS: Forty of 44 pancreatic carcinomas (91%) were diagnosed correctly by the methods of conventional cytology associated with p53 immunocytology. p53 mutations were detected in 12 of 14 cases that were positive for p53 (86%). Four of six cases that were inoperable due to massive metastasis or invasion had the mutation at codon 273 (CGT to CAT) in exon 8. CONCLUSIONS: These results suggest that p53 immunocytology reflects its gene mutations precisely, and that the point mutation at codon 273 (CGT to CAT) of p53 may play an important role in the invasive potential and metastasis of pancreatic carcinoma.

Adenocarcinoma↗
PubMed1998

Effect of protein kinase C inhibitors on cardioprotection by ischemic preconditioning depends on the number of preconditioning episodes.

OBJECTIVES: This study examined the possibility that the role of PKC in [corrected] PC, and thus the response to PFC inhibitors, may differ depending on how many ischemic episodes are employed to precondition the heart. METHODS: In the first series of experiments, myocardial infarct was induced by 30 min of coronary occlusion and 3 h of reperfusion in the rabbit. Infarct size was determined by tetrazolium staining and expressed as a percentage of area at risk (%IS/AR). Prior to the 30-min ischemia, rabbits were subjected to no PC, single PC (i.e., PC with an episode of 5 min ischemia/5 min reperfusion), and repetitive PC (2 cycles of 5 min ischemia/5 min reperfusion) with or without one of three treatments: polymyxin B (PolyB), staurosporine (Stauro), and 8-sulfophenylthephylline (SPT). In the second series of experiments, the rabbits received 5 min of coronary occlusion after repetitive PC with or without PolyB or Stauro treatment. Then, myocardial tissue in the ischemic region was sampled for assay of PKC activity. Untreated rabbits served as controls. RESULTS: Single and repetitive PC limited %IS/AR to the same extent (%IS/AR = 9.8 +/- 1.9 and 10.4 +/- 2.3, both p < 0.05, vs. the control value of 44.5 +/- 3.4), and single PC was blocked by PolyB (%IS/AR = 43.9 +/- 2.7) and Stauro (%IS/AR = 31.5 +/- 3.2). Although the protocol of PolyB injection maintained the plasma PolyB level during sustained ischemia well above its Ki for PKC, this agent and also Stauro failed to abolish the protection by repetitive PC (%IS/AR = 21.6 +/- 3.0 and 11.4 +/- 4.3, respectively). SPT, an adenosine receptor antagonist, not only blocked single PC (%IS/AR = 44.4 +/- 4.4) but also attenuated protection by repetitive PC (%IS/AR = 28.3 +/- 3.6). Infarct sizes in non-preconditioned hearts were not modified by PolyB, Stauro, or SPT. The ratio of membrane fraction PKC activity to cytosolic fraction PKC activity was elevated by repetitive PC plus 5 min ischemia, and this change in PKC was inhibited in hearts given PolyB and Stauro. CONCLUSIONS: In contrast to single PC, repetitive PC protects the heart against infarction even when PolyB and Stauro are administered to inhibit PKC during ischemic insult. This difference may be attributable to a PKC-independent mechanism, in which the adenosine receptor may be partly involved.

Animals↗
PubMed1998

Simple synthesis of sialyllactose-carrying polystyrene and its binding with influenza virus.

Glycoconjugate polystyrenes bearing sialyllactose moieties were prepared via a simple method from a mixture of alpha2-6 and a2-3 linked sialyllactose isomers of bovine milk origin. The reducing end of sialyllactose was converted to an amino function with ammonium hydrogen carbonate and then coupled with p-vinylbenzoyl chloride. The resulting styrene derivative substituted with sialyllactose via an amide linkage was polymerized with ammonium peroxodisulfate and N,N,N',N-tetramethylethylenediamine in water at 30 degrees C. The interaction of the glycopolymer with influenza A and B viruses was investigated by three different methods. The glycopolymer inhibited the hemagglutination of influenza A virus (PR/8/34) and its activity was 10(3) times higher than that of the oligosaccharide itself. The cytopathic effect of virus-infected MDCK (Madine-Darby canine kidney) cells was inhibited by the glycopolymer. The homopolymer showed 10(2) times higher inhibitory activity than naturally-occurring fetuin. It was also found that various viruses could be trapped by the glycopolymer adsorbed on a polystyrene surface. The inhibitory and trapping activities of the glycopolymers were correlated with the sialyl linkage specificities of the virus strains.

Animals↗
PubMed1998

Time window for the contribution of the delta-opioid receptor to cardioprotection by ischemic preconditioning in the rat heart.

The present study aimed to examine (1) whether the role of the opioid receptor in ischemic preconditioning (PC) is consistent regardless of the duration of ischemic insult and (2) which opioid receptor subtype contributes to PC. In the first series of experiments, the effects of PC, a nonselective opioid receptor antagonist (naloxone), and their combination on the infarct size after various durations of ischemia were assessed. In anesthetized, open-chest rats, the coronary artery was occluded for 20, 30, or 40 minutes to induce infarction and was reperfused for 3 hours, PC was performed with two cycles of 5-minute ischemia followed by 5-minute reperfusion before the sustained ischemia. At 25 minutes before the ischemia, naloxone was injected alone or in combination with subsequent PC. Infarct size was determined by tetrazolium staining and was expressed as a percentage of the risk area size (%IS/RA). In the second series of experiments, the effects of a delta-receptor-selective antagonist, naltrindole (NTI), and a kappa-receptor selective antagonist, nor-binaltrophimine (nor-BNI), on PC before 30-minute coronary occlusion were assessed. In untreated controls, %IS/RA was 53.1 +/- 3.2 after 20 minutes, 67.9 +/- 3.9 after 30 minutes, and 87.8 +/- 2.0 after 40 minutes of ischemia, respectively. PC significantly reduced %IS/RA after 20, 30, and 40 minutes of ischemia to 3.1 +/- 0.8, 12.8 +/- 1.1, and 42.1 +/- 4.3, respectively (P < 0.05 vs. each control). Naloxone (6 mg/kg) partially attenuated the protection afforded by PC when the sustained ischemia was 30 minutes (%IS/RA = 27.4 +/- 4.5; P < 0.05 vs. PC), but this inhibitory effect of naloxone was not detected when the duration of the ischemia was 20 or 40 minutes. NTI (10 mg/kg) also attenuated infarct size limitation by PC after 30 minutes of ischemia (%IS/RA = 25.6 +/- 3.7), but nor-BNI (10 mg/kg) failed to modify infarct size limitation by PC (%IS/RA = 13.3 +/- 3.2). The present results suggest that activation of the opioid delta-receptor partly contributes to preconditioning against infarction in the rat and that there may be a time window (at around 30 minutes after the onset of ischemia) for this opioid receptor-mediated protective mechanism.

Animals↗
PubMed1998

Synthesis of artificial glycoconjugate polymers starting from enzymatically synthesized oligosaccharides and their interactions with lectins.

Styrene derivatives substituted with N-linked beta-anomeric oligosaccharides were synthesized via a simple two-step procedure starting from three enzymatically prepared oligosaccharides: N-acetyllactosamine (Galbeta1-4GlcNAc), N-acetylisolactosamine (Galbeta1-6GlcNAc), and 4'-galactosyllactose (Galbeta1-4Galbeta1-4Glc). Their homo- and copolymerization with acrylamide using 2,2'-azobisisobutyronitrile as an initiator in dimethyl sulfoxide at 60 degreesC gave the corresponding glycopolymers. Binding between glycopolymers and lectins was investigated by means of hemagglutination inhibition experiments. The inhibition of RCA120 lectin-induced hemagglutination by N-acetyllactosamine-carrying homopolymer was about 10(3) times stronger than that of the oligosaccharide itself. The enhanced binding capacity with lectins can be explained in terms of a multivalent or cluster effect along the polymeric chain. In some combinations between lectins and polymers, the copolymers inhibited hemagglutination more strongly than the homopolymers did. N-Acetyllactosamine-carrying glycopolymer showed about 3 x 10(3) times weaker inhibition of DSA lectin-induced hemagglutination than the different type of N-acetyllactosamine-carrying glycopolymer which has an O-linked beta-anomeric phenyl aglycon of each repeating unit along a polyacrylamide backbone.

Biopolymers↗
PubMed1998

Infarct-size limitation by preconditioning is enhanced by dipyridamole administered before but not after preconditioning: evidence for the role of interstitial adenosine level during preconditioning as a primary determinant of cardioprotection.

Although the importance of adenosine (Ado)-receptor activation in preconditioning (PC) has been established, it is unclear whether cardioprotection afforded by PC is determined by the Ado level during PC ischemia or by that during sustained ischemia. Accordingly, we tested whether the PC effect is modified by augmenting the increase in the interstitial Ado level during PC or by that during sustained ischemia. In the first series of experiments, the effect of 0.25 mg/kg dipyridamole (DIP) on the interstitial Ado level was assessed by in vivo microdialysis in the rabbit heart. Dialysate Ado during 2-min ischemia was 70% higher in the heart pretreated with 0.25 mg/kg of DIP than in the untreated controls, indicating that DIP was capable of enhancing an ischemia-induced increase of interstitial Ado. In the second series of experiments, myocardial infarction was induced in the rabbit by 30-min coronary artery occlusion and 3-h reperfusion. Infarct size was determined by tetrazolium staining and expressed as percentage of area at risk (%IS/AR). Rabbits were subjected to one of nine treatments before the 30-min ischemia: no treatment, DIP (0.25 mg/kg, i.v.), PC with 2-min ischemia, DIP before 2-min PC, DIP after 2-min PC, PC with 3-min ischemia, DIP before 3-min PC, DIP after 3-min PC, or 8-sulfophenyltheophylline (SPT) after 3-min PC. DIP alone did not modify %IS/AR (38.8 +/- 5.8% vs. 41.2 +/- 4.7%), but administration of DIP before 2-min PC significantly enhanced the infarct size-limiting effect (14.6 +/- 2.1% with DIP vs. 32.1 +/- 4.7% without DIP). Although the 3-min PC per se could achieve significant infarct limitation, the effect of DIP on 3-min PC was not significant (14.7 +/- 1.9% with DIP vs. 20.5 +/- 1.8% without DIP). On the other hand, the effect of DIP administered after PC was very slight (only 7% reduction of %IS/AR) and statistically insignificant, regardless of the duration of PC ischemia. However, infarct limitation by 3-min PC was inhibited by SPT given after the PC (%IS/AR = 34.5 +/- 3.2), as reported previously. These results suggest that the interstitial Ado level during PC ischemia, not the level during sustained ischemia, is a primary determinant of the extent of cardioprotection by PC and that the threshold for Ado-receptor activation required during sustained ischemia is much lower than that for triggering PC.

Adenosine↗
PubMed1998

Suppression of reperfusion arrhythmias by preconditioning is inhibited by an ATP-sensitive potassium channel blocker, 5-hydroxydecanoate, but not by protein kinase C blockers in the rat.

It has been suggested that preconditioning (PC) against infarction in the rat heart is mediated by opening of ATP-sensitive potassium (KATP) channels, which may be induced by receptor-triggered activation of protein kinase C (PKC). However, the mechanism of suppression of reperfusion arrhythmias by PC remains unclear. This study first examined whether suppression of reperfusion arrhythmias by PC requires the activation of KATP channels, PKC, and opioid receptors. In anesthetized rats, reperfusion arrhythmias were induced by occluding the left main coronary artery for 5 min and subsequent reperfusion. In untreated control rats, the incidence of reperfusion ventricular tachycardia (VT) was 100%, and 80% of the VT deteriorated to ventricular fibrillation (VF). PC with 2-min ischemia/5-min reperfusion reduced the incidences of VT and VF to 30% and 0, respectively. Although a KATP channel blocker, 5-hydroxydecanoate (5-HD), alone caused no significant effect on the incidence of reperfusion VT, this agent blocked the suppression of reperfusion VT by PC (VT incidence, 91%). The incidence of reperfusion VF in the 5-HD-treated rats tended to be lower than that in the untreated controls and was not different between preconditioned and nonpreconditioned groups (30 vs. 27%). PKC inhibitors staurosporine and calphostin C modified neither reperfusion arrhythmias nor the antiarrhythmic effect of PC on reperfusion VT and VF. Naloxone (6 mg/kg, i.v.) did not alter the incidence or duration of VT in the nonpreconditioned heart. However, suppression of reperfusion VT by PC was prevented by naloxone (VT incidence, 70%). The incidence of reperfusion VF was similarly low in the naloxone-treated rats in both nonpreconditioned and preconditioned groups (20% vs. 0). In the second series of experiments, the effect of 5-HD on repetitive PC was assessed. Repetitive PC was performed with three cycles of 2-min ischemia/5-min reperfusion, which totally abolished reperfusion VT and VF. This antiarrhythmic effect of repetitive PC was not inhibited by 5-HD. These results suggest that KATP channels and opioid receptors may be partly involved in suppression of reperfusion arrhythmias, although their roles may be compensated for by other antiarrhythmic mechanisms in repetitive PC. In contrast with PC against infarction, PKC is unlikely to play a major role in PC against reperfusion arrhythmias in the rat.

Adenosine Triphosphate↗
PubMed1998

[Aortic stop flow and hypoxic perfusion chemotherapy for unresectable gallbladder cancer].

We performed the aortic stop flow and hypoxic perfusion chemotherapy for unresectable gallbladder cancer under general anesthesia and made the perfusion only in the abdominal cavity by clamping the abdominal aorta and inferior vena cava near the site of diaphragma. Although temporary hypertension occurred just after clamping the aorta, no severe problem could be seen during operation. After surgery the patient had no abnormalities such as liver or kidney dysfunction, and tumor markers gradually came to decrease. Furthermore, the effectiveness of this therapy is greatly anticipated for the unresectable abdominal cancer, evaluating the selection of anti-cancer drugs and their administration dosage etc.

Anesthesia, General↗
PubMed1998

[Telomerase activity in pancreatic juice for the preoperative diagnosis of pancreatic cancer].

Although many diagnostic challenges have been tried in pancreatic cancer, its prognosis still remains poor. One of the reason that it is difficult to diagnose using present diagnostic procedure in early stage of pancreatic cancer. Therefore, we tried new procedure using telomerase activity from pancreatic juice. In this study, telomerase was assayed by use of pancreatic duct cells obtained preoperatively from 32 cases with pancreatic duct abnormalities. Telomerase activity was undetectable in all 17 subjects with benign pancreatic diseases, whereas 13 (87%) of 15 subjects with pancreatic cancer had detectable telomerase activity. Interestingly, we also detected telomerase activity in the case of carcinoma in situ. If future studies confirm, the detection of telomerase activity of pancreatic duct cells may become an useful tool for diagnosis of pancreatic cancer, perhaps at early stages.

Adult↗
PubMed1997

Immunocytochemical detection of p53 protein as an adjunct in cytologic diagnosis from pancreatic duct brushings in mucin-producing tumors of the pancreas.

BACKGROUND: In cases of mucin-producing tumor (MPT) of the pancreas, a new clinical entity of pancreatic tumor, it has been reported to be difficult to distinguish adenoma from carcinoma preoperatively. This observation caused the authors to develop a new method of p53 immunocytochemistry using cytologic samples obtained by endoscopic retrograde pancreatic duct brushing (ERPDB). METHODS: Fifteen cases of MPT (9 with carcinoma and 6 with adenoma) were examined. In all cases, histologic diagnosis was determined by surgery or autopsy. A wire with a small brush was pushed into the dilatated pancreatic duct detected by endoscopic retrograde pancreatography (ERP). Specimens obtained by brushing were prepared on slides and subsequently fixed with ethanol. Papanicolaou staining and p53 immunocytochemistry were performed simultaneously. The ability of conventional cytology to distinguish adenoma from carcinoma was compared with that of p53 immunocytochemistry. RESULTS: Five of 9 cases (56%) with carcinoma of MPT were correctly diagnosed by Papanicolaou staining. Two of four cases, classified as benign by Papanicolaou staining, expressed p53 protein. Overall, 7 of 9 cases (78%) with carcinoma MPT were correctly diagnosed by Papanicolaou staining associated with p53 immunocytochemistry. In the cases with adenoma MPT, all cases were classified as benign by Papanicolaou staining and no case positive for p53 protein was encountered. CONCLUSIONS: These results suggest that p53 immunocytochemistry as an adjunct in cytologic diagnosis using ERPDB may contribute to differentiating adenoma from carcinoma MPT of the pancreas preoperatively.

Adenocarcinoma, Mucinous↗
PubMed1997

TP53 mutations in stage I gallbladder carcinoma with special attention to growth patterns.

32 stage I cases of gallbladder carcinoma (GC) were examined to evaluate TP53 mutations with special attention to growth patterns. Their growth patterns were classified into two types: polypoid (P-type) and flat (F-type). 16 cases of GC were classified as P-type and 16 as F-type. p53 immunohistochemistry was performed using a mouse monoclonal anti-p53 antibody. Mutations in exons 5-8 were examined by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) and direct sequencing. The incidence of p53 immunoreactivity was greater in the cases of F-type (11/16, 69%) than those in P-type (14/16, 25%) (P < 0.05). PCR-SSCP or direct sequencing revealed that TP53 mutations were detected in all cases positive for p53 protein. These results suggest that TP53 mutations may contribute to the carcinogenesis of the F-type GC, and than this pathway in the F-type may differ from that in the P-type GC.

Adenocarcinoma↗
PubMed1996

Immunocytochemical detection of p53 protein from pancreatic duct brushings in patients with pancreatic carcinoma.

BACKGROUND: It is often difficult to distinguish pancreatic carcinoma preoperatively from chronic pancreatitis. Therefore, we have developed a new method of detecting p53 immunoreactivity in cytologic material obtained by endoscopic retrograde pancreatic duct brushing (ERPDB). METHODS: Twenty-eight patients with prominent strictures of the main pancreatic duct demonstrated by pancreatography including 20 ductal cell carcinoma and 8 chronic pancreatitis were studied. The ability to distinguish between these two groups preoperatively by conventional cytologic examination was compared with p53 immunocytochemistry using ERPDB: RESULTS: The sensitivity, specificity, and overall accuracy of conventional cytologic examination in distinguishing ductal cell carcinoma from chronic pancreatitis were 60%, 100%, and 71% respectively. In comparison, the sensitivity, specificity, and overall accuracy of p53 immunocytochemistry in distinguishing were 90%, 100%, and 93%, respectively. The sensitivity of p53 staining of specimens from patients with carcinoma of the body or tail of the pancreas (90%) was the same for those with tumors of the head of the pancreas (90%). CONCLUSIONS: These results suggest that p53 immunocytochemistry using ERPDB in conjunction with conventional cytologic examination can help differentiate ductal cell carcinoma from chronic pancreatitis preoperatively.

Adenocarcinoma↗
PubMed1996

Cholecystokinin receptor antagonist, loxiglumide, inhibits invasiveness of human pancreatic cancer cell lines.

Recently, cholecystokinin has been reported to be important in regulating the growth of pancreatic cancer. We investigated the effect of loxiglumide (LXG), a cholecystokinin receptor antagonist, on the invasiveness of two human pancreatic cancer cell lines. Cells were treated with LXG for 24 h, and examined in the invasion assay. The expression and activity of MMP-9 in supernatants from cancer cells were analyzed by Western blotting and zymogram. Interestingly, the invasiveness of cancer cells and expression of MMP-9 were decreased by LXG in a dose-dependent manner. LXG may be a useful therapeutic agent against pancreatic cancer.

Blotting, Western↗
PubMed1996

K-ras and p53 mutations in stage I gallbladder carcinoma with an anomalous junction of the pancreaticobiliary duct.

BACKGROUND: An anomalous junction of the pancreaticobiliary duct (AJPBD) was thought to be an important risk factor for gallbladder carcinoma in Japan. In this report, we compared K-ras and p53 mutations in Stage I gallbladder carcinomas (GC) of patients with AJPBD with those in patients without AJPBD: METHODS: We examined 6 GC of patients with AJPBD and 20 GC of patients without AJPBD: Immunohistochemistry was performed for p53 protein. K-ras and p53 mutations were examined using genomic DNA extracted from the cancer regions. The methods of polymerase chain reaction (PCR) single strand conformation polymorphism analysis were performed for mutations in exons 5-8 of p53. The methods of PCR restriction fragment length polymorphism were performed for mutation in codon 12 of K-ras. RESULTS: p53 positivity was 67% in GC of patients with AJPBD and 65% in GC of patients without AJPBD: p53 mutations were found in exons 7 and 8 in GC of patients with AJPBD and in exons 5, 6, and 7 in GC of patients without AJPBD: The incidence of K-ras mutation in GC of patients with AJPBD (50%) was greater than that in patients without AJPBD (6%) (P < 0.05). CONCLUSIONS: These results suggest that K-ras mutation may be important in the early stage of carcinogenesis of the gallbladder mucosa with AJPBD, and that p53 mutations may also contribute to the early stage of carcinogenesis of the gallbladder mucosa, regardless of AJPBD:

Adenocarcinoma↗
PubMed1996

NOS-positive preganglionic neurons innervate a subpopulation of postganglionic neurons in superior cervical ganglion in rats.

To determine the postganglionic targets of NOS-containing preganglionic neurons, we studied the association of NADPH-diaphorase positive preganglionic fibers and retrogradely labeled postganglionic neurons in the superior cervical ganglion (SCG) in rats. Wheat germ agglutinin-horseradish peroxidase solution was applied to the anterior chamber of the eye, middle cerebral artery, subcutaneous layer of the facial skin, or submucosal layer of the inside of the lip. Two days after tracer application, the rats were perfused with fixative solution. Serial sections of the SCG were stained histochemically for NADPH-diaphorase followed by diaminobenzidine reaction. More than 80% of the labeled postganglionic neurons innervating the structures in the subcutaneous or submucosal layer showed close association with NADPH-diaphorase positive preganglionic nerve terminals; approximately one-third of these labeled neurons were encircled by dense baskets of pericellular terminals. On the other hand, most of the postganglionic neurons innervating the iris (69%) or the cerebral artery (90%) did not show a distinct association with NADPH-diaphorase positive terminals. These results suggest that one of the principal roles of the NOS-containing preganglionic neurons may be in controlling the postganglionic neurons which innervate the structures in the subcutaneous or submucosal layer.

Animals↗