Search PubMed⌕ Search

Biomedical subjects

M Imamura

Publications and source records attributed to M Imamura.

At least 649 records · Page 36Linked to original sources
PubMed1988

Substructure and higher structure of chicken smooth muscle alpha-actinin molecule.

Substructure of chicken gizzard smooth muscle alpha-actinin molecule was deduced by domainal mapping of the proteolytic fragments with alpha-chymotrypsin. There were three chymotryptic cleavage sites (Sites I, II, and III, from the amino terminus). Cleavage at Site I generated two fragments, i.e. an NH2-terminal 36-kDa fragment and a COOH-terminal 70-kDa fragment. The 70-kDa fragment generated either a 55-kDa fragment by cleavage at Site II or a 65-kDa fragment by cleavage at Site III. Purified NH2-terminal 36-kDa fragment bound to F-actin, whereas the 55-kDa fragment formed a dimeric molecule. Circular dichroism and electron microscopic experiments demonstrated that the alpha-helical content of the 55-kDa fragment was 14% higher than that of native gizzard alpha-actinin, coinciding with the apparently rod-shaped configuration of this fragment. A 110-kDa product was generated from two 55-kDa fragments in a cross-linking study with the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Two cross-linkable sites in the 55-kDa, A- and B-site, were shown to be involved in this reaction. Further, it was demonstrated by using N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide labeling and immunoblotting analyses that the A-site on one 55-kDa fragment was cross-linked to the B-site on the other. These results suggest that smooth muscle alpha-actinin formed an antiparallel dimeric molecule in which the 55-kDa fragments connected the two actin-binding domains composed of the 36-kDa fragments.

Actinin↗
PubMed1988

Pancreatic function and rehabilitation after pancreaticoduodenectomy.

Postoperative pancreatic function and rehabilitation were monitored in 149 patients who had had reconstruction of the digestive tract by Child's method, out of a total 151 patients who had undergone pancreaticoduodenectomy. The occurrence of peptic ulcer following Child's method may be prevented by the resection of a wider area of the stomach. Because the source of gut hormone secretion is removed by the pancreaticoduodenectomy, the secretion of this hormone is subsequently reduced and thus metabolic abnormalities also occur. If careful attention however, is paid to the maintenance of residual pancreatic function most patients who undergo pancreaticoduodenectomy can be expected to lead reasonably normal lives.

Duodenum↗
PubMed1988

Non-specific suppressor cells in murine bone marrow chimeras: their possible role in GVHD-associated immunodeficiency.

Suppressor cells against several mitogen-induced responses were detected in the spleen of murine bone marrow chimeras, regardless of intravenous (i.v.) or intrasplenic (i.s.) bone marrow transplantation (BMT). According to the time-course of the suppressor activity against Con A, PHA, and PWM, they were readily detected at 11-21 days after BMT and thereafter, either gradually decreased or remained at a plateau level. In contrast, the suppressor activity against the LPS-stimulated response increased at 39-52 days as compared to 24-34 days after BMT. Characterization studies of suppressor cells early (11-21 days) after BMT revealed that those in the i.v. and i.s. chimeras were composed of host-derived plastic dish adherent and/or anti-Thy 1.2 antibody-insensitive spleen cells in general. On the contrary, those in the i.v. and i.s. chimeras that possessed severer GVHD were mainly composed of host-derived plastic dish non-adherent spleen cells. Since the suppressor activity was higher in chimeras with severe graft-versus-host disease (GVHD) than in conventional chimeras, suppressor cells against the mitogen-induced responses may be related to the immunodeficiency associated with GVHD. Particularly, plastic dish non-adherent suppressor cells may closely relate to GVHD-associated immunodeficiency as compared with plastic dish adherent suppressor cells.

Animals↗
PubMed1988

Suppressor activity in the supernatant of T cell clones derived from chimeric mouse spleen cells.

The supernatant from cultures of T cell clones derived from (BALB/c----C3H/He) chimeras suppresses BALB/c anti-C3H/He or BALB/c anti-C57BL/6 MLRs. When we studied the alloantigen specificity of the suppressor activity in culture supernatant, we observed three types of the suppressor activity (i.e., the suppressor activity against BALB/c anti-C3H/He MLR, against BALB/c anti-C57BL/6 MLR, and against both MLRs) on day 3 after stimulation of the T cell clones with 20% crude IL2 and feeder cells. Since the alloantigen specificity fluctuated somewhat with time, we considered that a time-course study was needed to determine it correctly. We thought it unlikely that any IFN-gamma or PGE2 in the culture supernatant of the T cell clones would have mediated the suppression. Our results suggest that alloantigen specific and non-specific suppressor T cells exist in bone marrow chimeras. The former appears to play an important role in inducing and maintaining transplantation tolerance, while the latter seems to have a rather harmful effect upon chimeras.

Animals↗
PubMed1988

Transthoracic resection of esophageal cancer in patients with pulmonary dysfunction. Usefulness of high frequency ventilation during thoracotomy.

Although curative resection of esophageal cancer has become a safe procedure, in patients with pulmonary dysfunction, postoperative complications remain a serious problem. Of 122 patients who had transthoracic resection of esophageal cancer, 27 had pulmonary dysfunction; in six, the forced vital capacity was less than 70% (minimum of 42.8%, mean +/- SD of 56.6 +/- 8.9%); in 18, forced expiratory volume for one second (FEV1%) was less than 70% (minimum of 34.6%, mean +/- SD of 60 +/- 10%); and in three, both forced vital capacity and forced expiratory volume was less than 70%. Two patients had undergone hemipneumonectomy before receiving resection of the esophagus. During the intrathoracic operative procedure, high frequency ventilation was used, providing good surgical exposure and contributing to a decrease of postoperative pulmonary complications. There were no deaths during the month after surgery. The survival curve of these patients was not significantly different from that of other patients who had had esophagectomy for cancer of the esophagus. These patients survived for an average of 24 months. The patient who survived the longest has been alive for more than 11 years.

Aged↗
PubMed1988

Bone metabolism following gastric surgery: microdensitometry and single-photon absorptiometry.

The impairment of bone metabolism was investigated in patients who underwent gastrectomy or vagotomy with drainage two or more years ago. Serum biochemical analysis, microdensitometry of the 2nd metacarpal bone, and measurements of bone mineral content of the radius (measured 1/3 distally) using single-photon absorptiometry were performed at follow-up examination. Although serum levels of calcium, phosphorus and alkaline phosphatase were within normal range, alkaline phosphatase levels were slightly higher for the Billroth II group than for Billroth I. Twenty-eight of 50 gastrectomy cases (56%), and four of 10 vagotomy cases (40%) showed pathologically thin bone: microdensitometric (MD) scores were greater than 3. The Billroth II group showed a far higher frequency of greater MD scores than Billroth I. The MD scores showed significant positive relationship with the age at follow-up, but did not correlate well with the length of the postoperative period. Radial bone mineral content (BMC) was lower in patients with Billroth II anastomosis, or with total or proximal gastrectomy, than in those undergoing Billroth I. These results suggest that metabolic bone disorders following gastric surgery can be detected by MD score and BMC of appendicular bones. However, there was not sufficient resolution with these parameters to detect any bone changes in patients treated with active vitamin D3.

Adult↗
PubMed1988

[Pathophysiology following biliary reconstruction procedures, with special reference to gastric acid secretion, peptic ulcer, metabolism of carbohydrate and fat, and gastrointestinal hormone release].

Pathophysiological effects following biliary tract reconstruction for benign biliary diseases were investigated from the standpoint of gastric acid secretion, metabolism of nutrients and gastrointestinal hormone release. Patients undergoing Roux-Y hepaticojejunostomy showed a significant increase in maximum acid output at follow-up, although only one case of peptic ulcer was observed. In addition, the frequency of cases showing gastric acid hypersecretion was higher than for jejunal interposition hepaticoduodenostomy. Two kinds of test meals (carbohydrate-rich or fat-rich) were given, on different days, to each patient before and about four weeks after surgery. Plasma concentrations of gastrointestinal hormones and glucose or triglyceride were determined. Fasting concentrations of gut hormones (gastrin, GIP, insulin and GLI) were similar to those before surgery, and increased after the ingestion of the test meals. Gastrin and total GLI levels tended to be higher in the Roux-Y than in the interposition group, and vice versa for both insulin and GIP. The changes in plasma glucose and triglyceride, following the Roux-Y procedure, suggest disturbances in carbohydrate tolerance, fat digestion, and in the anabolic phase of absorbed fat. Patients undergoing the Roux-Y procedure should be carefully followed up, since gastric acid hypersecretion induced by a postprandial augmented release of gastrin was observed.

Adult↗
PubMed1988

Effects of the pathway of bile flow on the digestion of fat and the release of gastrointestinal hormones.

The effects of an altered pathway of bile flow upon fat metabolism and gastrointestinal hormone release were investigated in patients undergoing biliary reconstruction procedures or external biliary drainage. After ingestion of a fat-enriched meal, patients with jejunal interposition hepaticoduodenostomy showed the same patterns as controls, with similar levels of plasma triglyceride and gastrointestinal hormones. On the other hand, patients with Roux-Y hepaticojejunostomy or external biliary drainage revealed the impairment of fat metabolism, although the response patterns were different. As for the changes in gastrointestinal hormones in the two groups, both gastric inhibitory polypeptide (GIP) and insulin levels were reduced, whereas glucagon-like immunoreactivity (GLI) levels rose, especially in the external biliary drainage group. It is considered that the disturbance of fat metabolism, in cases of internal or external biliary diversion, is closely related to change in GIP, insulin, and GLI release, in addition to the impairment of mixed micelle formation by bile and of hydrolysis by pancreatic enzymes.

Adolescent↗