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Biomedical subjects

A Yamaguchi

Publications and source records attributed to A Yamaguchi.

At least 397 records · Page 22Linked to original sources
PubMed1993

Metal-tetracycline/H+ antiporter of Escherichia coli encoded by transposon Tn10. The structural resemblance and functional difference in the role of the duplicated sequence motif between hydrophobic segments 2 and 3 and segments 8 and 9.

The properties of site-directed mutants as to the putative hydrophilic loop region between hydrophobic segments 2 and 3 in the transposon Tn10-encoded metal-tetracycline/H+ antiporter (TET) were reported in our previous paper (Yamaguchi, A., Someya, Y., and Sawai, T. (1992) J. Biol. Chem. 267, 19155-19162). The loop between hydrophobic segments 8 and 9 contains a conserved sequence motif, GXXXXKXGEK, which is a derivative of the sequence motif, GXXXXRXGRR, in loop2-3. Site-directed mutagenesis studies on loop8-9 revealed that the two loops exhibit significant structural resemblance, that is, 1) when the Gly residue at the eighth position in each loop was replaced by various amino acid residues, the residual activity of the resultant mutants corresponded well to the beta-turn propensity of the substituent, 2) the Cys mutant as to the fourth position in each loop was most profoundly inactivated by N-ethylmaleimide among 10 Cys mutants as to each loop, and 3) the reactivity of a Cys residue introduced at the third position in loop8-9 with N-ethylmaleimide was lower than that in the case of the other Cys mutants, probably due to the residue being partially cryptic as to the attack of the reagent, similar to in the case of the corresponding residue in loop2-3, the latter being entirely cryptic. The Gly at the first position in loop8-9 is less important than the corresponding Gly in loop2-3, however, since the TET protein suffered a loss of activity when a bulky side chain was introduced at the first position in loop8-9 as well as in loop2-3, the structural roles of the 2 glycines are likely to be similar. These findings suggested that loop2-3 and loop8-9 may occupy similar positions in the three-dimensional structure of the TET protein. On the other hand, the two loops showed a significant functional difference; the negative charge of Asp66 and the positive charge of Arg70 in loop2-3 were essential for the transport function, but, in contrast, there was no functionally essential residue in loop8-9, indicating that loop2-3 may form an "active" leaflet in the TET protein, while loop8-9 may be a "silent" counterpart.

Amino Acid Sequence↗
PubMed1993

Hepatic resection using a water jet dissector.

A newly-designed water jet dissector was used for hepatic resections in humans. To evaluate its usefulness, the water jet dissector was compared to an ultrasonic surgical aspirator in terms of average blood loss and time of operation. In hepatectomies on patients associated with liver cirrhosis, the average blood loss during hepatic resection using the water jet dissector was significantly smaller (P < 0.05) than that with the ultrasonic surgical aspirator. However, in hepatectomies on patients without cirrhosis, the average blood loss during hepatic resection did not significantly differ between the two groups. Neither did the time of operation significantly differ between the two procedures in hepatectomies on patients with and without liver cirrhosis. No serious complications attributable to the use of the water jet dissector were encountered. The water jet dissector is thus considered to be a useful new device for use in the transection of the liver during hepatic resections.

Adenoma, Bile Duct↗
PubMed1993

Successful repair of combined ventricular septal rupture and free wall rupture.

The successful surgical repair of combined ventricular septal perforation and free wall rupture (double rupture) after inferior myocardial infarction is reported. Extensive inferior wall infarctectomy was performed, and both defects were closed with a prosthetic patch, using a modification of the technique developed by Daggett. The patient was alive and well 1 year after operation.

Heart Rupture, Post-Infarction↗
PubMed1993

Thoracoscopic stapled bullectomy supported by suturing.

In 1985, a thoracoscopic technique for closing bullae with hemostatic clips was developed. However, the method was limited, and therefore clinical application was small. A linear endoscopic stapler (Endo-GIA) was developed in 1990. The advent of the Endo-GIA nearly made thoracoscopic treatment of spontaneous pneumothorax practicable, and ended the use of clipping. In addition, a new operative technique was developed, the 3-cm minithoracotomy bullectomy for the treatment of spontaneous pneumothorax. This technique has now become obsolete. The current method is that of a thoracoscopic stapled bullectomy using the Endo-GIA, supported by suturing. The recurrence rate was 2.7% (1/37) using this method. The one recurrence occurred in a case where no bullae were observed during the operation. Our findings suggest that thoracoscopic stapled bullectomy supported by suturing is a practicable treatment of spontaneous pneumothorax. An economical use of the endoscopic stapler and complementary suturing may be less expensive than using a laser. Pleurodesis should be performed in the patients in whom no distinct bullae are discovered thoracoscopically.

Humans↗
PubMed1993

Enhanced negative slope of cortical potentials before sequential as compared with simultaneous extensions of two fingers.

Cortical potentials preceding voluntary sequential extension of the right middle finger followed by the index finger were compared with those preceding voluntary simultaneous extension of the two fingers in 7 right-handed subjects who were trained to make the total duration of the EMG discharges approximately the same between the two movements. The negative slope with the sequential movement started earlier and was larger, especially at the vertex and also at the bilateral precentral areas, as compared with the simultaneous movement. There was no difference in the Bereitschaftspotential amplitude between the two movements. It was postulated that a greater and earlier activation of the supplementary motor areas as well as the primary hand sensorimotor areas is associated, both bilaterally, with the execution of the unilateral sequential movement.

Adult↗
PubMed1993

Monoclonal antibodies that recognize antigens in human osteosarcoma cells and normal fetal osteoblasts.

Four monoclonal antibodies (HOB-1-4) that react against human osteosarcoma cells (Saos-2) and human fetal osteoblasts in situ were developed by immunizing mice with Saos-2 cells. HOB-1 (IgG1, k) and HOB-2 (IgM, k) stain cytoplasmic antigens in Saos-2 cells, human authentic osteoblasts and occasional cells in liver, spleen and, in the instance of HOB-1, kidney and adrenal gland. On Western blotting of Saos-2 cell lysates, HOB-1 recognizes a single protein species of M(r) 59,000, while HOB-2 reacts with a different species of M(r) 57,000. HOB-3 (IgG1, k) stains a cell membrane associated antigen in Saos-2 cells and osteoblasts in situ. The reaction pattern of this antibody is virtually identical to that seen in alkaline phosphatase (ALP)-positive cells in all organs examined immunohistochemically, except for intestinal epithelium. Both immunoblotting and immunoprecipitation analyses confirm that the antigen detected by HOB-3 is ALP. HOB-4 (IgG1, k) reacts weakly against Saos-2 cells cultured under standard conditions, but strongly following the exposure of the cells to the secretory inhibitor monensin. On frozen section screening, this antibody reacts preferentially with the collagenous extracellular matrix not only of the periosteum but of other tissues and organs as well. The precise identity of the HOB-4 antigen remains to be established. We suggest that these four monoclonal reagents will be useful adjuncts in characterizing the osteoblastic phenotype.

Alkaline Phosphatase↗
PubMed1993

p53 immunoreaction in endoscopic biopsy specimens of colorectal cancer, and its prognostic significance.

The expression of p53 protein was immunohistochemically studied in formalin-fixed paraffin-embedded biopsy specimens of 203 colorectal carcinomas by use of a monoclonal antibody specific for the p53 protein. PAb1801. p53 protein expression with its reactivity localised in nuclei was found in 121 (59.6%) of the cancers. There was no correlation of p53 immunoreactivity with histological classification, wall invasion, lymphatic invasion, venous invasion, lymph node metastases, or peritoneal metastases. p53-positive cancers were more frequently associated with liver metastasis than p53-negative ones. Patients with p53-positive tumours had significantly poorer prognoses than those with p53-negative tumours. The 5 year survival rate was 58.1% for patients with p53-positive tumours, and 76.3% for those with p53-negative tumours. In Dukes' stage C tumours, an especially good correlation was found between p53 immunoreactivity and prognosis. In addition, patients with p53-positive tumours had higher recurrence rates. The results indicate that p53 immunoreactivity may be a useful prognostic marker of colorectal cancers.

Antibodies, Monoclonal↗
PubMed1993

Inverse association of nm23-H1 expression by colorectal cancer with liver metastasis.

The expression of nm23-H1 mRNA and protein was studied in colorectal cancers by Northern blotting and immunohistochemistry. All 21 colorectal cancers studied by Northern blotting had increased levels of nm23-H1 mRNA relative to the adjacent normal colonic mucosa. Increased nm23-H1 protein expression was also observed in all 36 colorectal cancer cases including those studied by Northern blotting. There was no significant correlation between nm23-H1 expression and tumour histology, serosal invasion, lymphatic invasion, venous invasion, or lymph node metastasis. However, the expression of both mRNA and protein was significantly lower in tumours associated with liver metastasis than in those without such metastasis. These observations indicate that the nm23 gene may play a role in the suppression of liver metastasis of colorectal cancer.

Antibodies, Monoclonal↗
PubMed1993

Complementation of an Enterococcus hirae (Streptococcus faecalis) mutant in the alpha subunit of the H(+)-ATPase by cloned genes from the same and different species.

We isolated an Enterococcus hirae (formerly Streptococcus faecalis) mutant, designated MS117, in which 'G' at position 301 of the alpha-subunit gene of the F1F0 type of H(+)-ATPase was deleted. MS117 had low H(+)-ATPase activity, was deficient in the regulatory system of cytoplasmic pH, and was unable to grow at pH 6.0. When the alpha-subunit gene of E. hirae H(+)-ATPase was ligated with the shuttle vector pHY300PLK at the downstream region of the tet gene of the vector, it was expressed without its own promoter in MS117, and the mutation of MS117 was complemented; the mutant harbouring the plasmid had the ability to maintain a neutral cytoplasm and grew at pH 6.0. We next transformed MS117 with pHY300PLK containing the alpha-subunit gene of Bacillus megaterium F1F0-ATPase constructed in the same way. The transformant grew at pH 6.0, and the ATP hydrolysis activity was recovered. These results suggested that an active hybrid H(+)-ATPase containing the B. megaterium alpha subunit was produced, and that the hybrid enzyme regulated the enterococcal cytoplasmic pH, although the function of the B. megaterium enzyme did not include pH regulation. Thus, our present results support the previous proposal that the enterococcal cytoplasmic pH is regulated by the F1F0 type of H(+)-ATPase.

Bacillus megaterium↗
PubMed1993

Clinical diversity in biliary pancreatitis--classification of two types.

One hundred and seven patients with biliary pancreatitis undergoing operation from 1976 to 1989 were reviewed. To clarify the reason for failure to respond to conventional supportive therapy, 73 patients (68%) who underwent emergency surgery were retrospectively divided into two groups according to the severity of the pancreatitis evaluated at laparotomy and compared. Sixty-two had minimal or mild pancreatitis (Group I), among whom 44 (71%) had life-threatening acute biliary tract disease. All underwent biliary surgery and 4 (6%) subsequently died, 2 due to acute obstructive suppurative cholangitis. Eleven had hemorrhagic necrotizing pancreatitis (Group II), among whom 7 had complications of acute pancreatitis such as pancreatic ascites or abscess. These underwent pancreatic and/or biliary surgery and 3 (27%) died of multi-organ failure. There appears to be two types of biliary pancreatitis refractory to conventional supportive therapy, which differ in the extent of surgery required and in mortality: (1) minimal or mild pancreatitis with persistent life-threatening acute biliary tract disease (biliary type), and (2) more severe pancreatitis (pancreas type) early in the course of the disease.

Acute Disease↗
PubMed1993

[Mechanical dilation of the internal thoracic artery graft by using balloon catheter].

We evaluated the free flow of the internal thoracic artery grafts (ITA) which were dilated with a balloon catheter. Further, we examined the postoperative angiographic findings and histology of the ITAs by scanning electron microscopy. In 25 patients with internal thoracic artery grafting, the artery was dilated with a balloon catheter (Fogarty IMAG kit) that was withdrawn at tensions of less than 30 gm. The mean free flow rate of the left ITAs (LITAs) increased from 64.2 ml/min to 101.9 ml/min by injection of papaverine to ITAs (p < 0.05). The mean free flow rate of the balloon dilated LITAs were 160.8 ml/min which was significantly higher when compared with that of control and papaverine (p < 0.01, p < 0.01). The mean free flow rate of the balloon dilated right ITAs (RITAs) showed 183.2 ml/min, it was significantly higher (p < 0.01, p < 0.05) compared with that of control (78.4 ml/min) and papaverine (129.2 ml/min). Irregularity was documented in 16% of the ITAs in spite of the great patency rate (100%) from the postoperative angiogram. Using scanning electron microscopy, endothelial cell borders were well demarcated in the proximal portion of the dilated ITA. However, the distal portion of the endothelium displayed gradual destruction. Although mechanical dilation of the ITA graft by balloon calibration is very effective in increasing the free flow rate of ITA, we should be prepared for the intimal damage of the ITA graft.

Adult↗
PubMed1993

Correlation of p53 expression and proliferative activity in gastric cancer.

We analyzed immunohistochemically the association between p53 tissue status and prognostic parameters of 357 gastric cancer patients, using endoscopically obtained biopsy materials, embedded in paraffin. Using PAb1801, an anti-p53 monoclonal antibody p53 immunoreactivity was detected in the nuclei of cancer cells in 113 cases (32%). The nuclear p53 immunoreaction was closely associated with positive lymph node metastasis, serosal invasion, and liver metastasis. For the estimation of proliferative activity, proliferating cell nuclear antigen (PCNA) labeling rates (LRs) of biopsy specimens were immunohistochemically measured. A significant positive correlation was found between PCNA LRs and p53 tissue status. In addition, a positive nuclear p53 immunoreaction was found to be significantly associated with shorter overall survival. Especially, in the group of patients with stages III and IV, the prognosis of patients with p53-positive tumours was significantly poorer than that of patients with p53-negative tumours. These results indicate that immunohistochemical staining for nuclear p53 in biopsied materials may be useful in deciding the therapeutic schedule of patients with gastric cancer, preoperatively.

Antibodies, Monoclonal↗