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Biomedical subjects

M Kusunoki

Publications and source records attributed to M Kusunoki.

At least 181 records · Page 10Linked to original sources
PubMed1990

Mn K-edge XANES spectroscopy of a photosynthetic O2-evolving complex. High-quality pre-edge features and distinct fine structures in the S1- and S2-states.

High-resolution XANES (X-ray Absorption Near Edge Structure) spectroscopy for Mn in the S1 and S2 states of the spinach photosynthetic O2-evolving complex revealed distinct features in K-edge spectra, when a high signal-to-noise (S/N) ratio of ca. 80 with a low and constant background-to-signal (B/S) ratio of 0.15 to 0.18 was attained. Six features resolved in each S-state spectrum involve a pre-edge feature due to 1s----3d transitions, a main-edge feature possibly due to 1s----4s transitions and four fine structures superimposed on the principal absorption bands due to 1s----4p* transitions. The high-quality pre-edge features were analyzed according to a parametric ligand-field theory in comparison with those of some typical authentic Mn complexes. It was deduced that i) all of the four Mn ions in the S1-state are octahedrally coordinated and two of them constitute a di-mu-oxo bridged Mn(III, III) dimeric subunit; ii) the bridged Mn(III) ions are further bridged by a deprotonated water dimer, (HOHOH)-, and coordinated by imidazole-N and carboxylate-O- on the opposite side of the Mn atom from the di-mu-oxo bridge; iii) the other two Mn ions exist in the form of Mn(III) monomeric subunits; and iv) upon the S1----S2 transition, only the bridged Mn(III,III) is oxidized to Mn(III,IV). The distinct change in the principal absorption band shape upon the S1----S2 transition is briefly discussed to obtain the XANES evidence for a tetrameric Mn-cluster.

Cell Membrane↗
PubMed1990

A side reaction in solid phase synthesis. Insertion of glycine residues into peptide chains via Nim----N alpha transfer.

In solid-phase peptide synthesis using N alpha-Boc-Nim-tosyl-histidine (Boc-His(Tos)), byproducts having extra Gly residues in the peptide chain were observed at a high rate. When a Boc-amino acid such as Asn was incorporated after assembly of Boc-His(Tos), the Nim-tosyl group was partially or fully cleaved by an activating agent, 1-hydroxybenzotriazole. In the successive coupling reactions, Boc-Gly was incorporated into the free Nim ring as well as the alpha-amino function, and the Nim-Gly was then transferred to the alpha-amino group of Gly of the peptide chain after removal of these Boc groups to give extra Gly residues at the position of Gly. This was observed in only the coupling reaction with Boc-Gly and could be circumvented using a more stable Nim protecting group for His, such as a dinitrophenyl group.

Amino Acid Sequence↗
PubMed1990

Perioperative effect of methylprednisolone given during lung surgery on plasma concentrations of C3a and C5a.

Methylprednisolone or saline (placebo) solution was infused intravenously in 28 patients undergoing elective lobectomy for lung cancer. The state of the complement system during and after surgery and the effects of methylprednisolone on biologically active products of complement were studied by measurements of plasma C3a and C5a anaphylatoxins and leukocyte counts in peripheral blood perioperatively. In the placebo group plasma concentrations of C3a were significantly increased on postoperative days 1 and 2, whereas C5a had risen significantly 6 hours after surgery and on days 1 and 2. Methylprednisolone infusion during surgery eliminated the postoperative elevation of C3a and C5a. The postoperative leukocyte count in peripheral blood was higher in the methylprednisolone group than in the controls. The observations indicated that methylprednisolone may reduce the influx of leukocytes from peripheral blood into the airways by attenuating production of biologically active complements.

Complement Activation↗
PubMed1990

[Neurons in monkey parietal association cortex sensitive to depth movement].

We recorded neurons sensitive to depth movement from the inferior parietal lobule (area 7a) of alert behaving monkeys, and studied their response to changing sizes of retinal images and to changing binocular disparity. The size of the stimulus was changed by changing both the height and width of a slit in the same way, and the disparity change was produced by varying distances between a pair of polarized stimuli on a screen. Of 227 purely visual neurons recorded from 11 hemispheres of 7 monkeys, 32 neurons responded to the change of either the size or disparity, or both. Some of the neurons sensitive to size change could be activated by changing length on only one axis, but the optimal stimulus for most of them was a uniform change of size in all directions. The neurons sensitive to disparity change responded weakly to monocular stimuli, but showed clear selectivity in the direction of change of disparity when binocular stimuli were applied. We also found a group of depth movement sensitive neurons that responded maximally to the simultaneous change of size and disparity. This type of neurons may signal real depth movement by integrating the signals of size change and disparity change.

Animals↗
PubMed1990

Usefulness of valproate sodium for treatment of incontinence after ileoanal anastomosis.

We report on the excitatory effect of gamma-aminobutyric acid, which increased after the oral administration of valproate sodium, on anal canal resting pressure in human beings, gamma-aminobutyric acid receptors. We used this drug in order to improve continence after ileoanal anastomosis. Seventeen patients (eight with ulcerative colitis and nine with adenomatosis coli) were tested after receiving ileoanal anastomosis. The placebo showed no effect, but valproate sodium could ameliorate frequent defecation and soiling and the resulting perianal skin complications. Increasing anal resting pressure was also observed during valproate sodium administration without the amplitude, frequency of peristaltic wave, or voluntary squeeze pressure being affected. These results suggest that the subchronic administration of valproate sodium may be useful in the treatment of minor incontinence after ileoanal anastomosis.

Adult↗
PubMed1990

Conversion of malfunctioning J pouch to Kock's pouch. Case report.

A patient with ulcerative colitis previously treated with restorative proctocolectomy and ileal J-pouch anal anastomosis had recurrent pelvic abscess and poor functional results for 3 years postoperatively. To improve the quality of life, the J pouch was converted to a Kock's pouch. The successful result implies that Kock's continent ileostomy is a good replacement for failed pelvic pouch.

Abscess↗
PubMed1989

Different innervation mechanisms between the lesser and greater curvature of guinea pig antrum.

Transmural stimulation (TS) produced a frequency-dependent contraction of the longitudinal muscles from the lesser curvature of the guinea pig antrum, which was abolished by atropine. On the other hand, a response to TS of the strips from the greater curvature was biphasic: a rapid contraction followed by a relaxation, which was abolished by tetrodotoxin. By pretreatment with atropine, rapid contraction of the biphasic response evoked by TS in the greater curvature was abolished and relaxation was augmented. Relaxation to TS of the greater curvature was not affected by prazocine, yohimbine, phentolamine, propranolol, theophylline, apamin, alpha-chymotrypsin, and vasoactive intestinal polypeptide receptor antagonist. Different innervation mechanisms were suggested to be present in the longitudinal muscles between the lesser curvature (innervated with excitatory cholinergic neurons) and the greater curvature (innervated with excitatory cholinergic neurons and nonadrenergic inhibitory neurons) of the guinea pig antrum.

Animals↗
PubMed1989

Effect of dopamine on parathyroid hormone release during surgery.

There is much evidence that dopamine (DA) may play an important role in modulating parathyroid gland function. DA stimulates parathyroid hormone (PTH) secretion in cattle, which increases ionized calcium, but is without such effect on humans under normal physiological conditions. Ionized calcium plays a major role in muscle contraction including myocardial contractility. Therefore, we studied the PTH response to infusion of DA (4 micrograms/kg/min) under pathophysiological states during two different types of surgery; gastrectomy with halothane anesthetics and open heart surgery with high-dose fentanyl anesthetics. There was no change in PTH concentration, as measured by radioimmunoassay, in patients undergoing gastrectomy, although infusion of DA in these patients was effective in lowering the prolactin levels. However, plasma PTH concentration significantly increased where DA was applied (4 micrograms/kg/min) in patients undergoing open heart surgery. These results suggest that DA may stimulate PTH secretion by an indirect mechanism in humans under pathophysiological states, although details of the mechanism are unknown, and that there is the possibility that DA would indirectly regulate the levels of electrolytes such as ionized calcium and phosphate in patients undergoing open heart surgery mediated by elevation of PTH.

Calcium↗
PubMed1989

Prediction of arterial oxygen partial pressure from intrapulmonary venous admixture.

A short program was developed to predict the PaO2 at a given FIO2 by using arterial and mixed venous blood gas data obtained at an FIO2 of 1.0. Our program resolves Adair's equation and the shunt equation inversely, on the assumption that intrapulmonary venous admixture and the arteriovenous oxygen content difference remain constant during the study. The study was conducted on 19 patients with respiratory failure who were intubated and mechanically ventilated. According to linear regression analysis, regression coefficients of 0.91 and 0.97 were obtained between the measured PaO2 values and those estimated by the arterial/alveolar oxygen tension ratio (PaO2/PaO2) and our program, respectively (n = 23). The PaO2 values were predicted more accurately by our program than those calculated by PaO2/PaO2. Because our program is simple enough to be carried out with a pocket computer, it may be helpful in a bedside decision of lowering FIO2, especially in patients who require a high FIO2 level to maintain sufficient arterial oxygenation.

Blood Gas Analysis↗
PubMed1989

A SPECT study in internal carotid artery occlusion: discrepancies between flow image and neurologic deficits.

A SPECT (single photon emission computed tomography) study in internal carotid artery (ICA) occlusion was performed in 6 patients. The validity of iodoamphetamine (IMP) SPECT study in the evaluation of cerebral blood flow (CBF) or neurologic function is still controversial. In this study, the authors showed several cases in whom SPECT images of brain were not compatible with their neurologic deficits. In 2 typical cases, a large low-density area was observed in the non-dominant hemisphere in computed tomography (CT) scan, but no apparent motor-sensory deficits in left limbs were present. In these patients, SPECT study also revealed flow reduction in the affected side of the brain. So there was a possibility that an IMP brain image could not always reflect CBF, which maintains neurologic function of the brain.

Aged↗
PubMed1989

J-pouch: change of a method over years.

Since 1978, J. Utsunomiya has performed total colectomy, mucosal proctectomy and ileoanal anastomosis (IAA) in 105 patients and analysed their results in 97 patients consisting of 61 of familial polyposis (FP) and 36 of ulcerative colitis (UC) those who have been observed for two months to 10 years after operation. The operative procedures were classified in the three modalities. I. the "end to end-long cuff", II. "J-pouch-long cuff" and III. "J-pouch-short cuff" procedure. The success rate has been improved to 93.0% in the procedure III. compare with 74.1% in the II and 61.5% in the I. This improvement was achieved by preservation of reservoir continence, reduction of pelvic sepsis and less damaging of the internal sphincter during operation. Through a series of evolutional modification, the surgical technique has been established to the present method which is constructed with the four principal components: direct anastomosis of J-ileal pouch to the anus, short rectal cuff mucosectomy, anoabdominal approach at prone jack-knife position and routine use of defunctioning ileostomy. With this technique, both FP and UC patients enjoyed excellent or good function in 90% of the cases. Sex of the patient did not influence the functional result, but older patients showed poorer results compared with the younger patients. This procedure can provide a function comparable with ileorectal anastomosis with a technical difficulty similar to that of the abdominal pouch. All patients with FP or UC who require colectomy are candidates for IAA unless they are 60 years or older. For UC a three stage surgical procedure of IAA proceeded by open rectal excluding colectomy could improve the result.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Choledochal cysts. Oligoganglionosis in the narrow portion of the choledochus.

To investigate whether cystic dilation may be due to a reduction of postcholinergic cell bodies that leads to autonomic dysfunction, ganglion cell bodies were counted in five patients with choledochal cysts and five patients with normal choledochus. In the normal choledochus, the ganglion cell counts in the proximal and distal portions were 374.7 +/- 82.7/cm2 and 349.2 +/- 51.2/cm2, respectively. In cases of choledochal cysts, the ganglion cell counts in the dilated portion and narrow portions were 298.6 +/- 86.9/cm2 and 81.0 +/- 34.8/cm2, respectively. The cell ratio (narrow to dilated) was 0.271. Significant reductions of cell numbers were observed in all the choledochal cysts having various types of pancreatobiliary junctions. These findings indicate that the reduction in the number of ganglion cells in the narrow portion of the choledochal cysts supports the concept of oligoganglionosis in distal choledochus.

Adolescent↗
PubMed1988

Gallbladder dynamics and plasma cholecystokinin responses after meals, oral water, or sham feeding in healthy subjects.

To investigate the mechanisms controlling human gallbladder contraction, especially to determine the role of neural factors, the gallbladder response to various stimuli was evaluated in eight normal subjects using realtime ultrasonography. In addition, plasma cholecystokinin (CCK) levels were measured using a region-specific antibody (OAL 656). Intramuscular injections of CCK-8 and of cerulein induced mean maximal ejection fractions (EF max) of 50% +/- 6% and 58% +/- 4%, respectively. The mean EF max after ingestion of a fatty meal was 44% +/- 3%, while the EF max after a fat-restricted meal was significantly lower (17% +/- 4%). Oral water and sham feeding also significantly induced gallbladder contractions (EF max; 25% +/- 4% and 12% +/- 4% respectively) that were eliminated by premedication with atropine. The plasma CCK rose significantly after exogenous administration of CCK-8 and after ingestion of a fatty meal. The peak CCK concentration released after fatty meals was almost identical to that after exogenous CCK-8 loading. In contrast, plasma CCK levels showed no change after the fat-restricted meal, oral water and sham feeding. These findings suggest that not only CCK but also the cholinergic pathway may play important roles in the control mechanism of human gallbladder contraction.

Adult↗
PubMed1988

Effects of cholecystokinin octapeptide on contractile motility of guinea pig common bile duct.

Cholecystokinin octapeptide (CCK-8)-induced contraction and [3H]acetylcholine ([3H]-ACh) release from the longitudinal muscle strip of the guinea pig common bile duct were studied by a standard organ bath method and superfusion system. CCK-8 (10(-7) M) caused a biphasic contraction, a rapid phasic contraction followed by a fading tonic contraction. Hexamethonium, propranolol, and phentolamine had no effects on CCK-8-evoked contraction. Atropine or tetrodotoxin significantly reduced CCK-8-evoked initial phasic contraction and produced a rightward shift of the dose-response curve for CCK-8 (10(-10)-3 x 10(-7) M). CCK-8 provoked a significant [3H]ACh release in a dose-dependent manner, which was almost completely abolished by tetrodotoxin or Ca2+-free medium. These results suggest that CCK-8 receptors are present not only on the smooth muscle cells but also on the intramural cholinergic nerve cell bodies of the guinea pig common bile duct.

Animals↗
PubMed1988

Hypoxic contractile response in isolated human pulmonary artery: role of calcium ion.

The mechanism for hypoxic pulmonary vasoconstriction (HPVC) was investigated in human pulmonary arterial strips. Hypoxia in the presence of histamine (10(-6) M) caused marked pulmonary arterial contraction, which was reversed by O2. The hypoxic contraction in the presence of histamine was inhibited by diphenhydramine, but not by cimetidine. The hypoxic histamine-mediated contraction was attenuated but still present in the absence of extracellular Ca2+, or by the inhibitors of voltage-dependent Ca2+ influx. However, it was inhibited significantly by a further depletion of intracellular Ca2+, or by HA 1004, an intracellular calcium antagonist. A low concentration (10(-7) M) of a calcium ionophore, A23187, enhanced the hypoxic contraction in the presence of histamine, whereas procaine completely inhibited it. W-7, a calmodulin inhibitor, significantly decreased the hypoxic histamine-mediated contraction, but 12-O-tetradecanoylphorbol-13-acetate (TPA), a C-kinase promotor, had no effect. The hypoxic contractile response was also observed in the presence of both A23187 and KCl instead of histamine, but the hypoxia-induced contraction with KCl alone was much smaller than that. These results indicate that hypoxia in the presence of certain other vasoactive agents has a potent contractile effect on the human pulmonary artery and that the response is dependent on Ca2+. Enhancement of both Ca2+ influx and Ca2+ release from intracellular storage sites by hypoxia, which interacts with calmodulin, were suggested to be involved in the mechanism of HPVC.

Aged↗