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Biomedical subjects

T Kawata

Publications and source records attributed to T Kawata.

At least 217 records · Page 12Linked to original sources
PubMed1989

Effects of food preservatives and local anesthetics on synthesis of outer membrane proteins in Vibrio parahaemolyticus.

The effects of seven food preservatives including salicylate, benzoate, dehydroacetate, sorbate and propionate, and two local anesthetics, phenethyl alcohol and procaine, on the synthesis of major outer membrane proteins in Vibrio parahaemolyticus strain 3283-61 were investigated. The synthesis of the outer membrane proteins a, b, c and e was remarkably inhibited by all the food preservatives except propionate and two additional outer membrane proteins with respective molecular weights of about 35,000 (protein b') and 32,000 (protein c') were induced. Similar effects were encountered by the local anesthetics except that the synthesis of protein e was only weakly depressed.

Anesthetics, Local↗
PubMed1989

Effects of dietary protein intake on renal function in humans.

The effects of an acute protein load on renal hemodynamic responses and plasma glucagon levels were investigated in 31 patients with biopsy proven chronic glomerulonephritis (24 cases) or chronic renal failure (6 cases). After baseline clearance measurements, the subjects ingested a high protein meal consisting of 1.2 to 1.5 g protein/kg body weight in the form of cooked beef followed by a second set of measurements. This acute protein load resulted in a rise of both creatinine and PAH clearances (from 86.5 +/- 6.0 ml/min to 98.3 +/- 7.1 ml/min and 531.1 +/- 59.1 ml/min to 688.9 +/- 72.9 ml/min, respectively). This was associated with an elevation of plasma glucagon levels from 104.6 +/- 7.9 pg/ml to 134.5 +/- 7.5 pg/ml. From these data we suggest that the augmentation of renal function following a high protein intake may be mediated by the simultaneous rise of plasma glucagon levels, and that the glucagon concentration in the portal vein rather than in the peripheral blood has a pivotal role in this setting.

Adolescent↗
PubMed1989

[Surgical treatment of postinfarction ventricular septal perforation--the difference between a cardiogenic shock group and a congestive heart failure group].

Twelve patients with postinfarction ventricular septal perforation (VSP) were divided into 2 groups based upon the preoperative status and the time interval between the operation and the occurrence of VSP after acute myocardial infarction (AMI). Group I were in cardiogenic shock unresponsive to either pharmacologic supports or IABP, and needed an emergency repair of VSP. The other group (group II) were in congestive heart failure responding to some extent to pharmacologic supports and IABP, and VSP of this group was repaired on the elective or semiemergency basis. Group I comprised of 7 patients, 5 males and 2 females, with a mean age of 65.9 +/- 12.6 years, and group II included 5 patients, 2 males and 3 females with an averaged age of 72.6 +/- 3.4 years. The mean time duration between AMI and the operation, and between the occurrence of VSP and the operation were 3.1 and 1.6 days in group I and 13.4 and 8.0 days in group II. The operative mortalities were 57% in group I and 0% in group II, a remarkable difference. The reasons why group I had a poor prognosis were analysed and were found as follows: (1) group I sustained a larger AMI of anteroseptal area together with the lateral and/or inferior infarctions more often than group II. (2) Group I had frequently multiple organ failure (MOF) even prior to operation due to cardiogenic shock. (3) Group I had severer right ventricular failure than group II, in which the right atrial pressure was markedly elevated. In group I, the right heart failure remained and was prolonged even after surgery reflected by the RAP/LAP ratio over 1 and finally resulting in MOF. To improve surgical results in group I, the operation should be undertaken on the emergency basis before MOF is completed, and patch reconstruction of the left ventricular free wall is recommended in patients with a wide AMI and a high positioned anterior septal perforation. When RV failure is dominant, not only a LV assist device but also a RV assist device may also improve the results.

Aged↗
PubMed1989

[A case of dumbbell neurogenic tumor in the posterior mediastinum].

We have recently experienced a dumbbell tumor that developed in the posterior mediastinum in a 64-year-old male. The patient suffered from dorsalgia one year and a half previously. Chest X-ray examinations revealed a well-defined boundary in the right posterior mediastinum. Myelography followed by computerized tomographic scanning (CT) revealed that the tumor developed in a paravertebral area linked with a vertebral canal through an intervertebral foramen and destructed a rib in growing in the paraspinal muscular layer. Longitudinal incision of about 10 cm was made downward from immediately above the first thoracic spinous process, and the chest was opened by posterolateral incision extending into the muscles of the back in an arc shape. The tumor was entirely excised by additional laminectomy. Since malignant schwannoma was diagnosed histologically, Linac X-ray of 50 Gray was given. The patient is now enjoying his healthy daily life with no postoperative complication 2 years after operation. Myelography followed by CT was proved to be quite useful in evaluating a relationship between the tumor and the spinal cord in the diagnosis of this disease.

Humans↗
PubMed1988

DNA-binding protein(s) interacts with a conserved nonameric sequence in the upstream regions of wheat histone genes.

A nuclear protein(s), HBP-2, that binds to the upstream region of the wheat histone H4 gene was identified from a fractionated nuclear extract of wheat germ by DNase I footprinting. The DNase I-protected region contained the conserved nonameric motif, CATCCAACG. Cross-competition experiments that used the mobility shift assay showed that this nuclear protein(s) binds specifically to the upstream sequence that has been postulated to be a cis element of the wheat H3 gene. Our findings suggest that this DNA-binding protein(s) may be a trans-acting factor in the regulation of the transcription of wheat histone genes.

Base Sequence↗
PubMed1988

Resetting of tubuloglomerular feedback in acute volume expansion in rats.

Loss of sensitivity or "resetting" of tubulo-glomerular feedback has been reported after both acute and chronic volume expansion in rats. In chronic volume expansion due to dietary salt loading, resetting was found to result from the appearance of an inhibitory factor in tubular fluid. The aim of the present study was to test the possibility that resetting after acute isooncotic volume expansion may also be due to such an inhibitor. Rats were acutely volume expanded (4.5% of body weight) by infusion of a solution of fresh plasma and Ringer's solution. Tubuloglomerular feedback activity was assessed in expanded and control animals by measuring early proximal flow (EPF) rate during perfusion of the loop of Henle at varying rates with proximal tubular fluid harvested from the control (control TF) and expanded animals (AVE TF). When loops of Henle in control animals were perfused with control TF at 10, 20 or 40 nl min-1, EPF fell from (mean +/- SD) 29.8 +/- 5.6 at zero loop flow to 27.5 +/- 7.5, 21.1 +/- 4.2 and 15.5 +/- 4.5 nl min-1 gKW-1 respectively. Perfusion at the same rates with control TF in expanded animals reduced EPF from 39.5 +/- 9.6 (at zero loop flow) to 35.9 +/- 11.3, 31.6 +/- 4.3 and 22.9 +/- 6.8 nl min-1 gKW-1 respectively. When loops of Henle in control animals were perfused with AVE TF, EPF fell from 28.6 +/- 9.5 (zero loop flow) to 23.5 +/- 8.6, 19.9 +/- 8.2 and 15.6 +/- 6.5 nl min-1 gKW-1 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Increased tubuloglomerular feed-back mediated suppression of glomerular filtration during acute volume expansion in rats.

1. Volume expansion is currently believed to change the intrinsic properties of the juxtaglomerular apparatus such that the sensitivity of the tubuloglomerular feedback (TGF) mechanism is reduced, thus allowing glomerular filtration rate, and hence salt and water excretion, to rise. Recent studies conflict with this view and indeed the older literature reveals that the rise in glomerular filtration rate (GFR) under these conditions is far more modest than would be expected if TGF control were eliminated. 2. To investigate this problem, TGF control of filtration rate was examined by measuring single-nephron glomerular filtration rate (SNGFR) during loop of Henle perfusion at varying rates in rats under control conditions, after acute, moderate (4% of body weight), iso-oncotic volume expansion and in rats treated with antibodies to atrial natriuretic peptide (ANP) prior to the acute volume expansion. 3. With TGF control of filtration interrupted by filtrate collection from the proximal tubule, SNGFR in the expanded rats was massively increased compared with controls, although SNGFR measured in the distal tubule, and hence with TGF control intact, was only modestly increased, as was whole-kidney filtration rate. Loop perfusion at increasing rates up to 30 nl min-1 progressively decreased SNGFR in controls, and in the expanded rats the range over which control was exerted extended up to 60-80 nl min-1. For changes in loop flow around the spontaneous operating point, the sensitivity of the TGF mechanism, defined as delta SNGFR/delta loop flow, was similar in both groups. Treatment of rats with ANP antibodies prior to volume expansion substantially blunted the changes in renal salt and water excretion and the increase in SNGFR seen in the absence of loop perfusion. 4. These results are not consistent with a diminution of TGF function after volume expansion, rather with an enhancement. The latter is best accounted for by vasodilation of preglomerular resistance vessels on volume expansion, a result predicted by calculations from a model based on the serial arrangement of preglomerular and TGF-controlled vascular resistance elements and the established pharmacological actions of ANP.

Animals↗
PubMed1988

The control of glomerular filtration rate and renal blood flow in chronically volume-expanded rats.

1. Chronic volume expansion by dietary salt loading practically abolishes tubuloglomerular feed-back (TGF) by means of a humoral inhibitor in tubular fluid. Elimination of the vasoconstrictor influence of feed-back does not, however, increase glomerular filtration rate (GFR) and renal blood flow (RBF), implying that chronic salt loading induces additional preglomerular vasoconstriction. This being so, the feed-back response which, although absent in free-flowing nephrons, can still be elicited by loop of Henle perfusion with Ringer solution, should be essentially normal, except that nephron GFR at any loop perfusion rate should be lower than in controls. Persistence of RBF, GFR and nephron GFR autoregulation would imply that autoregulation is achieved by a preglomerular resistance control system independent of feed-back. 2. These hypotheses were tested by clearance and micropuncture experiments in rats chronically fed a diet containing 40 g NaCl (kg food)-1. 3. RBF and GFR autoregulation indeed persisted, the former down to 90 mmHg compared with 105 mmHg in controls. In controls, nephron GFR measured distally was autoregulated down to 90 mmHg whereas that measured proximally was autoregulated only above 105 mmHg. In high-salt rats nephron GFR from both sites was autoregulated to 90 mmHg. 4. Loop of Henle perfusion with homologous tubular fluid in high-salt rats confirmed attenuation of feed-back. Loop perfusion with Ringer solution yielded a response comparable to that in controls (maximal reduction of nephron GFR to 57%, compared with 56% in controls). Absolute nephron GFR at any loop perfusion rate was lower in high-salt rats than in controls. 5. These observations confirm the initial hypotheses. Considering feed-back and autoregulation as independent, preglomerular resistance control mechanisms, together with elementary haemodynamic considerations, allows formulation of a renal haemodynamics model whose quantitative predictions regarding characteristics of RBF, GFR and feed-back control are remarkably consistent with the literature.

Animals↗
PubMed1988

Excellent patency and growth potential of internal mammary artery grafts in pediatric coronary artery bypass surgery. New evidence for a "live" conduit.

Coronary artery bypass grafting in pediatric patients provides a unique opportunity to evaluate the characteristics of graft material. Twelve pediatric patients with severe coronary artery involvement secondary to Kawasaki disease underwent coronary artery bypass grafting with internal mammary artery and autologous saphenous vein grafts. Eleven patients were boys and one was a girl; their ages ranged from 5 to 13 years (mean age +/- SD, 8.7 +/- 3.0 years). These 12 patients had 17 internal mammary artery and 11 autologous saphenous vein grafts with a mean value of 2.3 +/- 0.7 grafts per patient. Five patients underwent bilateral internal mammary artery grafting with or without concomitant autologous saphenous vein grafting. There was no mortality, and all patients are leading almost normal lives, although strenuous exercise is still prohibited for some. Biplanar cineangiography was performed before and 1 month after (early postoperative period) coronary artery bypass grafting in all patients and was repeated more than 1 year after (late postoperative period) bypass in eight patients. Changes in graft diameter and graft length were assessed by computer-assisted graphic analysis of 10 internal mammary artery grafts and of seven saphenous vein grafts between the early and late postoperative periods. Patency rates of saphenous vein grafts and of internal mammary artery grafts were 91% and 100%, respectively, at the early postoperative period (p = NS), and 50% and 100%, respectively, at the late postoperative period (p less than 0.05). In addition to the excellent patency of internal mammary artery grafts in the late postoperative period, an in situ internal mammary artery graft was found to have grown 125% in length with 112% body growth (112% body surface area) (r = 0.88, p less than 0.001) and to have enlarged 149% in diameter when the native coronary stenosis was tight. In contrast, the lengths of saphenous vein grafts either failed to change or were slightly decreased at the late postoperative period (p = NS). Growth potential of the internal mammary artery graft provides a new demonstration of the viability and adaptability of this graft. We conclude that the internal mammary artery graft is a "live" conduit with potential for growth and adaptation. This growth potential may be the most important reason for its excellent long-term patency, which suggests that in situ internal mammary artery grafts are the graft of choice for pediatric coronary artery bypass grafting.

Adolescent↗
PubMed1987

Nuclear protein(s) binding to the conserved DNA hexameric sequence postulated to regulate transcription of wheat histone genes.

Nuclear protein(s) that specifically bind(s) to the upstream hexamer motif, ACGTCA, of wheat histone H3 and H4 genes has (have) been identified. Sequences homologous to this hexamer are found to be conserved in the upstream region of not only wheat histone genes but also other plant and animal histone genes. This suggests a possible role(s) for the hexamer and the nuclear protein(s) in the transcriptional regulation of the wheat histone genes. This hexamer is homologous to the upstream core sequence, TGACGTCA, which is highly conserved in some animal genes whose expression is regulated by cAMP.

Binding, Competitive↗
PubMed1987

A new orthodontic force system of magnetic brackets.

Tooth movement in orthodontic treatment is achieved by a combination of mechanical and physiologic forces acting on the teeth and their supporting structures to effect the biologic changes that cause teeth to move through bone. Traditional orthodontic appliances using wires, springs, and elastic forces inevitably cause some degree of discomfort and pain. In the present study, a new magnetized edgewise bracket was designed. The magnet works to move teeth mesiodistally and is not merely a mechanical force. It is well adapted to the biophysical system of tooth and bone interrelationships. Therefore, it works effectively, gives less discomfort, and produces less stress for the patient. The new magnetic appliance provides a force system that approaches the ideal orthodontic requirements.

Adolescent↗
PubMed1987

Electron microscopic demonstration and isolation of ribosomes in mesosomes from Staphylococcus aureus.

Mesosomes of Staphylococcus aureus 209P were observed to be extruded as tubules upon protoplast formation by electron microscopy and isolated under hypertonic conditions to maintain their structural integrity by differential centrifugation followed by sucrose density gradient centrifugation. Isolated mesosomes were composed of long, branched tubules of irregular sizes and they were shortened during purification. Thin sections of isolated mesosomes showed that the mesosomal tubule was surrounded by a triple-layered membrane and contained ribosome-like particles in diameter of about 15 to 20 nm. These particles were isolated from purified mesosomal preparation by disrupting the mesosomal tubule with deoxycholate and Triton X-100 under hypotonic conditions followed by a linear sucrose density gradient centrifugation. Negatively stained preparations of the isolated particles revealed the same appearance as those of the ribosomes isolated from the cytoplasm. The mesosomal particles sedimented at 70S in sucrose gradients in the presence of 10 mM Mg2+, but they were dissociated into two subparticles, 50S and 30S subunits, upon lowering the Mg2+ concentration to 1 mM. These findings indicate that the mesosomal tubule is packed with ribosomes.

Centrifugation, Density Gradient↗
PubMed1987

Characterization of mesosomes of Micrococcus luteus: isolation and properties of mesosomal ribosomes, and localization of penicillin-binding proteins in mesosomal membranes.

Mesosomes were isolated and purified from Micrococcus luteus under hypertonic conditions throughout preparation processes. The purified mesosomal preparation was composed of closed tubules and vesicles. Electron-dense ribosome-like particles were observed within the isolated mesosomal vesicles by electron microscopy. The ribosome-like particles were isolated from the purified mesosomes by a procedure involving solubilization of the membranes with detergents followed by centrifugation on a linear density gradient of sucrose. The isolated particles have a sedimentation coefficient of 70S in the presence of 10 mM Mg2+, when Mg2+ concentration was lowered to 0.1 mM, the particles were dissociated into two sub-particles of 30S and 50S. The 70S particles had the same appearance as cytoplasmic 70S ribosome particles upon observations of negatively stained preparations. These findings indicate that mesosomal tubules contain ribosomes. The isolated mesosomal ribosomes had the ability for protein synthesis when polyuridylic acid-directed polyphenylalanine synthesis was assayed. The sensitivity of mesosomal ribosomes to inhibitors, chloramphenicol and streptomycin, for protein synthesis was significantly lower than that of both cytoplasmic and cytoplasmic membrane-bound ribosomes. In addition, three penicillin-binding proteins were detected in the mesosomal membranes. One of these was localized predominantly in the mesosomal membranes and the other two were distributed almost equally in both mesosomal and cytoplasmic membranes.

Bacterial Proteins↗
PubMed1987

Purification and immunochemical properties of a wall protein antigen from Clostridium difficile ATCC 11011.

A wall-surface protein antigen, designated 32K antigen, was extracted from whole cells of Clostridium difficile strain ATCC 11011 with phosphate buffered saline and purified by ion-exchange chromatography, gel filtration, and chromatofocusing. The 32K antigen preparation was determined to be highly homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition of the antigen was characteristic in the predominance of the acidic amino acids, the very low contents of methionine and histidine, and the lack of cysteine. A monomeric molecular weight of the 32K antigen was estimated to be 32,000 by SDS-PAGE and 30,200 by sedimentation equilibrium. The antigen exhibited two isoelectric forms (IP, 4.12 and 3.96). Neither carbohydrate nor phosphorus was detectable in the antigen. The antigen was relatively resistant to trypsin but sensitive to pepsin. Immunoblot analysis of the wall proteins isolated from other strains of C. difficile probed with monospecific antiserum against the antigen from ATCC 11011 showed that the antigenicity of 32K wall protein was common among some of the strains containing 32K wall proteins.

Amino Acids↗