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Biomedical subjects

M Kusunoki

Publications and source records attributed to M Kusunoki.

At least 145 records · Page 8Linked to original sources
PubMed1992

Three-dimensional structure of ferricytochrome c' from Rhodospirillum rubrum at 2.8 A resolution.

The structure of ferricytochrome c' extracted from Rhodospirillum rubrum has been determined by the X-ray crystallographic method. Crystals in hexagonal space group P6(1), with unit-cell dimensions a = b = 51.72 A and c = 155.49 A, contain one dimer molecule composed of chemically identical polypeptide chains (monomer I and monomer II) per asymmetric unit. An electron density map has been calculated at a resolution of 2.8 A by the multiple isomorphous replacement method using four-circle diffractometer data from native crystals and two heavy-atom derivatives. The quality of the map was improved by averaging the electron density about the non-crystallographic 2-fold axis relating the two monomers. The initial three-dimensional model of monomer I was built on a computer graphics system and that of monomer II was derived from monomer I using the non-crystallographic symmetry matrices. The dimer structure has been refined using a combination of simulated annealing and conventional restrained least-squares crystallographic refinement. The current model includes 244 amino acid residues (122 x 2) and 2 hemes, with a root-mean-square deviation in bond lengths from ideal values of 0.022 A. The current crystallographic R-factor is 23.3% for 4,481 independent reflections [magnitude of Fo greater than or equal to sigma (F)] between 5.0 and 2.8 A resolution. The monomer molecule is structurally organized as an array of four nearly parallel alpha-helices which construct a left-twisted bundle. One end of the bundle, in which a covalently bound protoheme IX prosthetic group is incorporated, is more divergent than the other.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Protein kinase C activity of colonic mucosa in ulcerative colitis.

Protein kinase C (PKC) activity was measured in the inflamed colonic mucosa of 24 patients with ulcerative colitis and in the normal colonic mucosa of 10 patients with other benign diseases. The particulate fraction activity in ulcerative colitis mucosa was significantly increased compared with that of normal mucosa (320 +/- 47 versus 200 +/- 30 pmol/min/mg protein; p less than 0.05). Inflamed ulcerative colitis mucosa also showed significantly increased total PKC activity in the particulate fractions compared with normal mucosa (147 +/- 26 versus 37 +/- 8 pmol/min/mg tissue; p less than 0.05). Mucosal samples from ulcerative colitis patients were divided into 12 with mild and 12 with severe inflammation by histologic examination. The particulate PKC activity of severely inflamed mucosa was significantly lower than that of mildly inflamed mucosa (p less than 0.05). These results indicate that colonic inflammation in ulcerative colitis may be associated with altered cellular PKC activity.

Adult↗
PubMed1992

Increased protein tyrosine kinase activity of the colonic mucosa in ulcerative colitis.

The protein tyrosine kinase (PTK) activity was measured in the inflamed colonic mucosa of 12 patients with ulcerative colitis and in the normal colonic mucosa of 12 control patients with colon cancer. The specific PTK activity in the particulate fraction obtained from ulcerative colitis mucosa was significantly increased compared with that of normal mucosa (5.10 +/- 0.60 pmol/min/mg versus 2.12 +/- 0.44 pmol/min/mg protein; p less than 0.05). Inflamed ulcerative colitis mucosa also showed a significantly higher total PTK activity in the particulate fraction than normal mucosa (2.60 +/- 0.42 pmol/min/g versus 0.91 +/- 0.16 pmol/min/g tissue; p less than 0.05). Mucosal samples from ulcerative colitis patients were divided into those with mild and those with severe inflammation on histologic examination (n = 6 each). The particulate PTK activity of severely inflamed mucosa was significantly higher than that of mildly inflamed mucosa (p less than 0.05). These results suggest that colonic inflammation in ulcerative colitis is associated with alterations in cellular PTK activity.

Adolescent↗
PubMed1992

Functional role of the preserved rectal cuff in ileoanal anastomosis.

BACKGROUND: This study included 16 patients without complications, eight patients with ulcerative colitis, and eight patients with familial adenomatous polyposis. All patients underwent colectomy, mucosal proctectomy, and ileoanal anastomosis in the jackknife position with complete removal of the rectoanal columnar mucosa above the dentate line (IAA) through the anus. METHODS: The patients were divided into two groups: eight patients with the rectal cuff about 7 cm from the dentate line, "the medium-cuff group," and eight patients who underwent resection of the rectal stump above the levator, leaving a cuff of 2 cm, "the minimum-cuff group." RESULTS: In the medium-cuff group the percent recovery of maximum resting pressure and maximum squeeze pressure 12 months after IAA were not significantly decreased, the rectoanal inhibitory reflex recovered in 87.5% of patients, and all patients regained continence. In the minimum-cuff group, however, the percent recovery for both pressures remained significantly reduced, the reflex never recovered, and only 25% of the patients were continent after 12 months (p less than 0.05). There was no significant difference in capacity or distensibility of the ileal pouch between the groups. CONCLUSIONS: These results indicate that the medium-cuff method was associated with a superior functional result compared with the minimum-cuff method in the early postoperative period and the cuff in the lower rectum connected with the visceral nerves should be preserved to achieve better bowel function in the patient undergoing IAA. The initial mucosectomy through the anus in the prone jackknife position is useful for this purpose.

Adenomatous Polyposis Coli↗
PubMed1992

Characteristics of anal canal motility after ileoanal anastomosis.

This study attempted to determine the mechanism of anal canal motility after ileoanal anastomosis with the use of alpha-, beta- and muscarinic receptor agents. Forty-five patients, 19 +/- 2 months after operation (mean plus or minus S.E.M.) and 48 control volunteers were studied. Anal manometry indicated no difference in maximum resting pressure and squeeze pressure between the patients and the normal controls. Greater amplitude and less frequent anal canal slow waves were a particular characteristic during the postoperative period. Phentolamine (alpha-blocker) exhibited a stimulatory effect on anal resting tone in the normal rectum, while propranolol (beta-blocker) and atropine (muscarinic blocker) had no effect. However, alpha-, beta- and muscarinic receptors all had stimulatory effects on postoperative anal tone. The muscarinic receptor had dominant effects on the reduction in anal canal slow wave frequency after ileoanal anastomosis. Our results indicated that neorectum after ileoanal anastomosis had hybrid characteristics of both rectum and ileum. Through analysis of receptor-related motor function, we may be able to improve our understanding of dyscontinence after ileoanal anastomosis.

Adenoma↗
PubMed1992

Modified anoabdominal rectal resection and colonic J-pouch anal anastomosis for lower rectal carcinoma: preliminary report.

BACKGROUND: There has recently been increasing interest in coloanal reconstruction after proctectomy for low rectal carcinoma. We describe here our pilot experience with seven patients undergoing modified anoabdominal resection of the rectum and a colonic J-pouch anal anastomosis. METHODS: The procedure varied according to the extent of internal anal sphincter (IAS) resection (type a, partial resection of the upper IAS; type b, circumferential resection of the upper IAS; type c, partial preservation of the lower IAS; and type d, total resection of the IAS). RESULTS: None of the patients had incontinence, but preservation of the lower half of the IAS (types a and b) showed functional superiority over more extensive IAS resection (types c and d). Only patients who underwent types c and d resection needed medications to reduce stool frequency. CONCLUSIONS: Our results suggest that the lower half of the IAS has a more important role than the upper half in the control of defecation. Total resection of the IAS did not sacrifice continence, but preservation of at least the lower IAS resulted in a better quality of life. Careful patient selection is needed when considering the use of these procedures for tumors in the lowest part of the rectum.

Adenocarcinoma↗
PubMed1992

Gastric volvulus complicating myotonic dystrophy.

Myotonic dystrophy is an autosomal inherited disorder of both striated and smooth muscle, and is considered to be a rare cause of gastrointestinal dilatation and abnormal peristalsis. We report on a patient with myotonic dystrophy complicated by gastric volvulus. A 57-year-old female with myotonic dystrophy suddenly developed abdominal pain, nausea and vomiting. X-ray examinations revealed gastric dilatation and pyloroantral obstruction, consistent with acute gastric volvulus. The patient underwent successful emergency gastrectomy. Gastric volvulus is often an unrecognized surgical emergency, but its clinical and radiographic features are so characteristic that accurate diagnosis is possible if the condition is kept in mind. Thus, the clinician should consider the possibility of gastric volvulus when evaluating gastrointestinal complaints in patients with myotonic dystrophy.

Acute Disease↗
PubMed1992

Treatment of scaphoid fractures with carpal instability.

Since 1981, I treated 81 scaphoid fractures: 14 wrists (group A) with acute unstable fracture, 37 (B) with ununited fracture accompanied by dorsiflexed intercalated segment instability (DISI), and 30 (C) with ununited fracture without DISI. The methods and results were evaluated retrospectively. Bone union occurred in 100% of group A wrists, 92% of group B, and 90% of group C. By a modification of Cooney's clinical scoring chart, mean scores were 91 in group A, 84 in group B, and 87 in group C. In 43% of group A, a scapholunate gap remained after surgery. Of 21 wrists in group B treated by bone graft and screw fixation, union was not achieved in one; in another 13, the R-L angle was corrected to within 10 degrees of the unaffected side. In group C, DISI did not develop if bone union occurred. There was correlation between shortness of the scaphoid and DISI remaining. The clinical scores of wrists with and without DISI were not different, except for patients who did hard manual labor, in half of whom the score was poor when DISI remained. Cineradiography of ununited fractures was done before and after surgery. For three wrists in group B, plain X-ray films showed that DISI improved, but cineradiography showed that DISI was present; even without static DISI, there may be dynamic DISI. Treatment of acute unstable fractures of the scaphoid by reduction and internal fixation generally gave satisfactory results. Perhaps when ligament injury may have caused instability, ligament repair or reconstruction is needed. For ununited fractures with DISI, correction of the DISI was needed as well as bone union. If union occurred with the scaphoid shorter than normal, DISI was present, so restoration of the length of the scaphoid during surgery is mandatory.

Adolescent↗
PubMed1992

Occult cancer in localized giant pseudopolyposis.

Localized giant pseudopolyposis is a rare complication in patients with ulcerative colitis which progresses to a huge intramural polypoid mass. Our case described here is a 30-yr-old female with chronic ulcerative colitis who developed localized giant pseudopolyposis with unexpected infiltrating adenocarcinoma. This case is one of an unusual form of cancer presentation in ulcerative colitis, and it indicates that we should be aware of the possibility of occult adenocarcinoma inside a large pseudopolyposis with no superficial dysplasia.

Adenocarcinoma↗
PubMed1991

Protein kinase C activity as marker for colorectal cancer.

Protein kinase C (PKC) activity was measured in normal-appearing colonic mucosa from patients undergoing colonic resection. Comparisons were made between cases with and without colorectal cancers. PKC activity in cytosolic and particulate fractions was significantly reduced in patients with colorectal cancer: 40 +/- 9 and 114 +/- 29 (pmol/min/mg) respectively, compared with patients without cancer; 129 +/- 11 and 250 +/- 38 (pmol/min/mg) (p less than 0.05). Normal-appearing colonic mucosa in patients with cancer showed significantly decreased total PKC activities in the cytosolic and particulate fractions compared with those in patients without cancer (10 +/- 1 and 20 +/- 3 vs. 30 +/- 2 and 33 +/- 6) (pmol/min/g tissue) (p less than 0.05). The cellular distribution (% particulate fraction) of PKC activity in normal-appearing mucosa in patients with cancer (64%) was higher than in patients without cancer (49%) (p less than 0.05). OUr data suggest that PKC activity may be used as a biological marker of risk of developing colorectal cancer or risk of bearing an asymptomatic tumor.

Biomarkers, Tumor↗
PubMed1991

Structural and functional modifications of the manganese cluster in Ca(2+)-depleted S1 and S2 states: electron paramagnetic resonance and X-ray absorption spectroscopy studies.

The effect of extraction of weakly bound Ca2+ by low-pH treatment on the O2-evolving apparatus was studied by use of low-temperature electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy. In low-pH-treated PSII membranes, an S2 EPR multiline signal with modified line shape was induced by illumination at 0 degrees C, but its signal amplitude decreased upon lowering the excitation temperature with concomitant oxidation of cytochrome (cyt) b-559 in place of Mn. The half-inhibition temperature for formation of the modified multiline signal was found at -33 degrees C, which was much higher than that for formation of the normal S2 state in untreated control membranes. Signal IIf was normally induced down to -30 degrees C, but its dependence on excitation temperature was different from that for modified S2. This was interpreted as indicating that the low-temperature blockage of modified S2 formation is due to the incapability of electron abstraction from the Mn cluster. The Mn K-edge of X-ray absorption near-edge structure (XANES) spectrum shifted to lower energy by 0.8 eV after low-pH treatment, but the shift was reversed by addition of Ca2+. Upon illumination at 0 degrees C of treated membranes, the K-edge energy was up-shifted by 0.8 eV, but was not upon illumination at 210 K. These results were interpreted as indicating that extraction of weakly bound Ca2+ by low-pH treatment gives rise to structural and functional modulations of the Mn cluster.

Calcium↗
PubMed1991

Altered protein tyrosine kinase levels in human colon carcinoma.

To further understand the molecular mechanisms and the biological indicators of colonic tumorigenesis, the authors examined tyrosine kinase activity in the cytosol and in the particulate fraction of the homogenates of specimens from 20 human colonic carcinomas and compared them with the adjacent normal mucosal tissues. Total protein tyrosine kinase activity could be precisely detected using miniphosphocellulose column purification and a synthetic peptide, Glu-asparagine (Asp)-alanine (Ala)-Glu-tyrosine (Tyr)-Ala-Ala-arginine (Arg)-Arg-Arg-glycine (Gly) (E11-G1), as an artificial substrate. Tyrosine kinase activity of colonic carcinoma and normal mucosa was reduced in the cytosol fraction whereas activity in the particulate fraction was elevated with respect to protein concentration. The average specific activity ratios were 1.95 +/- 0.27 (normal cytosolic/carcinoma cytosolic) and 0.57 +/- 0.01 (normal particulate/carcinoma particulate) for tyrosine kinase activity. Cellular distribution (% cytosol) of tyrosine kinase activity in normal mucosa and in carcinoma varied from 21.0% to 91.2% and from 7.0% to 61.4%, respectively. In nearly all cases the percentage of cytosolic tyrosine kinase activity in carcinoma tissues was lower than in normal tissues. There was no difference due to histologic type or the presence of adenomatous components. A significant decrease of cytosolic tyrosine kinases was correlated with Dukes' Stage A. With advancing Dukes' stage, the average specific activity ratios (normal cytosol/carcinoma cytosol) were decreased. This study indicates that colonic carcinogenesis might be associated with alterations in cellular levels of tyrosine kinase activity and that the average specific activity ratio (normal cytosol/carcinoma cytosol) had a possible correlation with colonic tumor growth.

Colonic Neoplasms↗
PubMed1991

Function after anoabdominal rectal resection and colonic J pouch--anal anastomosis.

Twenty-eight patients undergoing anoabdominal resection of the rectum with construction of a colonic J reservoir and eight patients without a reservoir were studied 2 years after surgery. Frequency of defaecation and daytime soiling were inversely correlated with the maximum tolerable volume of the colonic J pouch. The distensibility and threshold volume of those with a pouch were significantly greater than in those without a pouch 6 months or more after stoma closure. Anal resting pressure, squeeze pressure, anal canal length and a positive inhibitory reflex were similar in both groups. Anal resting pressure, squeeze pressure and pouch distensibility correlated with frequency of defaecation in the stable phase. Pouch construction may improve the patient's quality of life in the adaptation phase.

Adult↗
PubMed1991

Heterogeneity of response to exercise of rat muscle pyruvate dehydrogenase complex.

Muscle glucose uptake is greatly stimulated by moderate exercise, but full oxidation of the glucose to CO2 depends on the activity of the pyruvate dehydrogenase (PDH) complex. Our aim was to determine how PDH complex in different muscle groups responds to varying periods of moderate exercise. Rats were run on a motor-driven treadmill for 5-30 min and muscle PDH complex activity was determined in heart, diaphragm and red quadriceps muscles after isolation of mitochondria in the presence of inhibitors of PDH complex interconversion. In heart and diaphragm muscle, exercise caused an increase in PDH complex activity after 5 min, but this was followed by a significant decrease in activity as exercise progressed. In red quadriceps muscle, PDH complex activity was reduced after 5 min of exercise and was decreased further as exercise continued. We conclude that increased duration of exercise can lead to reduced PDH complex activity in rat muscles. We propose that this is a consequence of elevated fatty acid oxidation, the products of which stimulate PDH kinase. This implies that increased glycolysis to lactate and increased fatty acid oxidation can simultaneously provide energy for contracting muscle.

Animals↗