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Biomedical subjects

J Sakata

Publications and source records attributed to J Sakata.

At least 19 recordsLinked to original sources
PubMed1999

Cell density of adrenomedullin-immunoreactive cells in the gastric endocrine cells decreases in antral atrophic gastritis.

AIMS: Adrenomedullin (AM) is a novel hypotensive and vasorelaxing peptide recently isolated from human phaeochromocytoma tissue, and is widely distributed in various organs. In this study we examined the localization of AM-immunoreactive (IR) cells in the gastric mucosa and AM-IR cell density in antral atrophic gastritis. METHODS AND RESULTS: Gastric mucosal tissues were taken from the gastric body and antral mucosa of 52 patients (27 men, 25 women; mean age 56.0 (range 20-86) years). Immunohistochemical analysis revealed that AM-IR cells were present in the pyloric glands, but not in the fundic glands, and that AM-IR cells were stained positively for chromogranin A and gastrin. The percentage of AM-IR cells vs chromogranin A- and gastrin-IR cells was 42 and 56%, respectively. The number of AM-IR cells decreased with the progression of severity of atrophic changes in the pyloric gland, and also of mononuclear cell infiltration. There was no correlation between the number of AM-IR cells and the degree of neutrophilic infiltration. Similar findings were also obtained for gastrin-IR cells. CONCLUSION: AM-IR cells are present in the endocrine cells including gastrin-IR cells in the pyloric glands. These results suggest that AM may contribute to gastrin secretion in the pyloric glands.

Adrenomedullin↗
PubMed1998

[Surgical stabilization of multiple rib fractures successfully achieved with the use of long metalic plates].

Surgical stabilization of multiple rib fractures in 5 male patients was successfully achieved with the use of orthopedic A-O metalic plates, which are called reconstruction plates. In each patient, we prevented deformity of the rib cage and flail chest which frequently occurs after multiple rib fractures. Three of these patients received emergency operations because of severe hemopneumothorax and flail chest due to crushing injuries to the chest. They were treated by the standard thoracotomy, hemostasis of intrapleural bleeding, and stabilization of fractured ribs with reconstruction plates, in addition two of the patients underwent a single lobectomy to control the pulmonary hemorrhage. Another two patients were treated with mechanical ventilation and closed-tube thoracotomy following the chest trauma because their thoracic bleeding from drainage tubes was tolerable. But flail chest and respiratory insufficiency did not improve, in spite of positive controlled ventilation as a mode of internal pneumatic stabilization. Then surgical stabilization of the fractured ribs with these plates was carried out ten to twelve days after the accidents in each case. All patients tolerated the surgical procedures well and were successfully removed from the respirator, demonstrating complete stability of the chest wall. The long metal reconstruction plates with many perforations were very useful for the external fixation of segmentary fractured ribs as an external brace. This was because they were long enough to cover the whole length of the fractured ribs and moderately soft enough to be appropriately bent or twisted by hand at the time of operation. Moreover a number of holes in it allowed the suture to pass through the plate and rib, avoiding displacement of the prosthesis. This is the first report which describes the usefulness of orthopedic reconstruction plates for the stabilization of multiple rib fractures.

Adult↗
PubMed1998

Adrenomedullin in the gastrointestinal tract. Distribution and gene expression in rat and augmented gastric adrenomedullin after fasting.

The aim of this study was to investigate the regional distribution, molecular forms, and gene expression of adrenomedullin in the rat gastrointestinal tract and to examine physiological changes in gastric adrenomedullin after 24-h fasting. The tissue concentration was measured by radioimmunoassay. The molecular forms were analyzed by high performance liquid chromatography. mRNA levels were quantified by Northern blotting and cells positive for adrenomedullin immunoreactivity were localized by immunohistochemistry. A high concentration of adrenomedullin was found in stomach, cecum, and colon (450-520 fmol/g wet tissue). Adrenomedullin immunoreactivity was also detected in duodenum, jejunum, and ileum (200-250 fmol/g wet tissue). Transcripts of the adrenomedullin gene were widely expressed throughout the gastrointestinal tract. The major form of adrenomedullin immunoreactivity in stomach and colon corresponded precisely with authentic adrenomedullin peptide. Adrenomedullin immunoreactive cells were present in the gastrointestinal endocrine system. The concentration and mRNA level of gastric adrenomedullin after fasting were significantly increased compared with findings in controls. Adrenomedullin is ubiquitous in the gastrointestinal tract, and may be produced by endocrine cells. The results suggest that adrenomedullin, through its potent vasodilating activity, may play some role, in the stomach including the regulation of the mucosal blood flow.

Adrenomedullin↗
PubMed1998

Developmental effects on intersexual and intrasexual variation in growth and reproduction in a lizard with temperature-dependent sex determination.

The mechanisms that control growth and reproduction have received considerable attention by molecular and cellular endocrinologists, yet there has been relatively little effort to link these two aspects of physiology. On the other hand, evolutionary biologists have long commented on the relationship between growth and reproduction in many species, yet have generally neglected the mechanisms underlying such complex traits. An approach that integrates the multiple proximate levels promises to provide significant insight into the evolution of neuroendocrine control mechanisms. In this chapter, we take this approach in reviewing environmental influences on growth and reproduction in the leopard gecko, Eublepharis macularius. In this species, incubation temperature during embryonic development not only determines gonadal sex, but also underlies within-sex differences in growth, adult morphology, aggressiveness, reproductive physiology and behaviour, and brain organization. Thus, the leopard gecko is an excellent model to elucidate the developmental interactions among the environment and the endocrine and nervous systems that control growth and reproduction.

Animals↗
PubMed1998

Comparison of clinical outcome between histidine-triptophan-ketoglutalate solution and cold blood cardioplegic solution in mitral valve replacement.

BACKGROUND: This study was conducted to compare the effect of histidine-triptophan-ketoglutalate solution (HTK) with that of cold blood cardioplegic solution (CBC) in mitral valve surgery. METHOD: Forty-six patients who underwent mitral valve replacement between January 1994 and December 1996 were enrolled in this study. Twenty patients received HTK (HTK group), while 27 patients had CBC (CBC group) as myocardial protection. HTK was given as a single high dose, whereas CBC was used in the usual multidose format. RESULT: The doses of inotropic agent at the end of extracorporeal circulation did not differ between the HTK group and the CBC group. Creatine kinase values (units) on day 1 and day 2 were 1140+/-412, 921+/-436 for the HTK group and 904+/-335, 816+/-420 for the CBC group, respectively (p = NS). Spontaneous defibrillation occurred in 26% of the CBC group and 90% of the HTK group (p < 0.05). Pacing was temporarily used in 20% of the HTK group and 44% of the CBC group after extracorporeal circulation (p < 0.05). CONCLUSIONS: These results suggest that HTK provided more adequate myocardial protection in mitral valve surgery.

Blood↗
PubMed1998

Distribution and expression of adrenomedullin in human gastrointestinal tissue.

Adrenomedullin (AM) is a biologically active peptide recently isolated from phaeochromocytoma. We report here the distribution and characterization of immunoreactive AM and gene expression of AM in human gastrointestinal tissue. Using a sensitive radioimmunoassay system for the peptide, immunoreactive human AM was detected in the stomach, duodenum, jejunum, ileum and colon. The AM concentration of these tissues was about 0.4-0.8 pmol/g wet tissue. Reverse phase and gel filtration high-performance liquid chromatographies showed that most of the immunoreactive AM in stomach and jejunum was identical to authentic human AM. By northern blot analysis, human AM mRNA was found to be expressed ubiquitously in the human gastrointestinal tissues. Furthermore, an immunohistochemical study revealed that immunoreactive AM cells were present in the gastrointestinal glands. These results suggest that AM may play some role as a gastrointestinal hormone.

Adrenomedullin↗
PubMed1998

Decrease in circulating and urine adrenomedullin concentrations in stroke-prone spontaneously hypertensive rats.

Adrenomedullin (AM) is a peptide with potent vasodilatory and hypotensive properties. Plasma AM levels in rats with experimentally induced hypertension, such as Dahl salt-sensitive rats and two-kidney, one-clip hypertensive rats, are higher than those in normotensive rats. We previously noted, however, that plasma AM levels in spontaneously hypertensive rats (SHR) are similar to those in Wistar-Kyoto rats. To define the role of AM in rats with severe hypertension, we investigated changes in circulating and tissue AM levels in stroke-prone spontaneously hypertensive rats (SHRSP/Izm). The immunoreactive rat AM levels in plasma, urine, and tissue measured with a sensitive radioimmunoassay, and the AM mRNA levels in various tissues in 15-wk-old SHRSP/Izm were compared with those in age-matched Wistar-Kyoto rats (WKY/Izm). The plasma and urinary AM levels in SHRSP/Izm were significantly lower than those in WKY/Izm [plasma AM, 2.14+/-0.06 (SE) vs. 3.24+/-0.16 fmol/ml, p< 0.001; urinary AM, 16.36+/-3.21 vs. 36.12+/-6.09 fmol/ml, p< 0.01]. A negative correlation was found between the plasma AM level and the systolic blood pressure in both SHRSP/Izm and WKY/Izm. Reverse-phase high-performance liquid chromatography showed that the molecular components of plasma immunoreactive AM in SHRSP/Izm were similar to those in WKY/Izm. Furthermore, tissue AM levels in various organs in SHRSP/Izm were not lower than those in WKY/Izm. In conclusion, low levels of circulating AM may contribute to the maintenance of high blood pressure in 15-wk-old SHRSP/Izm. These low plasma AM levels may be caused by accelerated metabolism of circulating AM in SHRSP/Izm.

Adrenomedullin↗
PubMed1997

The method for keeping low perfusion flow weaning from centrifugal pumps: an evaluation of hemolysis in the circulator units.

Currently, the clinical application of extracorporeal and assisted circulation using centrifugal pumps is becoming popular. However, a problem in the use of centrifugal pumps is the difficulty in controlling the flow rate when it is a low range. Although we have been controlling the flow rate with a control unit that simply squeezes the blood outlet tube from the outside, hemolysis resulting from turbulent flow in the tube was discovered. Therefore, this control procedure was evaluated experimentally. Two groups were tested as follows: in Group A (n = 10), the tube was squeezed from the outside using the control unit, and in Group B (n = 10), no control unit was used. Blood in each circuit was circulated at 1,500 rpm, and the flow rate was controlled to 250 ml/min using the control unit for Group A. Time-course changes of lactate dehydrogenase (LDH) and free hemoglobin in the blood were measured during 8 h of circulation. There were no significant differences between the 2 groups in the mean values of LDH and free hemoglobin. Therefore, the present low flow rate control provided by the control unit makes it appear to be a simple and useful apparatus for controlling blood circulation using centrifugal pumps.

Analysis of Variance↗
PubMed1997

Experimental studies on three types of heparin-coated cardiopulmonary bypass circuits.

In cardiovascular operations, we have usually used heparin-coated cardiopulmonary bypass circuits with low systemic heparinization. Three types of heparin-coated cardiopulmonary bypass circuits are available in Japan: 2 of the 3 have covalent heparin bonding, and the other has ionic heparin bonding. We studied these circuits in ex vivo experiments to explore which were the best in terms of biocompatibility. In this study we compared the Carmeda system (Medtronic) and the Capiox system (Terumo) with covalent heparin bonding, and the Duraflo-II (Baxter) with ionic heparin bonding, evaluating them in ex vivo experiments. They were primed with fresh human blood, and we studied and compared the platelet counts, fibrinogen, D-dimmer, beta-thioguanine (TG), thrombin-antithrombin complex (TAT), and C3a and C4a of each of them. Additional research will be presented in the future.

Anticoagulants↗
PubMed1997

Our distal aortic perfusion system in descending thoracic and thoracoabdominal aortic aneurysm repairs.

We have used heparin-bonded partial cardiopulmonary bypass to support distal aortic circulation during aortic cross-clamping. However, there were no cardiotomy reservoirs with fully reliable thromboresistance. To resolve this problem, a short-acting anticoagulant (nafamostat mesilate) was added into a cardiotomy reservoir. The present study was designed to evaluate the efficacy of our distal perfusion system. From May 1995 through the end of May 1996, 27 patients underwent descending thoracic and thoracoabdominal aortic aneurysm repairs with this adjunct, 4 being excluded from the experiment. Twenty patients who had undergone conventional partial cardiopulmonary bypass were defined as the control group. There were no significant differences between the 2 groups in the morbidity, mortality, gas transfer, or transfusion requirements despite the fact that more complicated surgical procedures (shown by a two-fold increase in the prevalence of reoperation) were required in the group that had received the current distal perfusion adjunct the heparin-bonded group. In conclusion, our perfusion system is very effective for descending thoracic and thoracoabdominal aortic aneurysm repairs.

Analysis of Variance↗
PubMed1997

Changes in cardiac adrenomedullin concentration in renovascular hypertensive rats.

We assessed changes in tissue and plasma adrenomedullin levels in two-kidney, one-clip renovascular hypertensive rats. Four weeks after clipping, adrenomedullin concentrations were significantly higher in the cardiac ventricles and lower in the left atrium than the respective values in sham-operated rats. The left ventricular adrenomedullin concentration significantly correlated with systolic blood pressure and the degree of cardiac hypertrophy. No difference was noted in the adrenomedullin concentrations of the adrenal gland, aorta, lung, kidneys, or plasma between the two groups. These findings indicate possible involvement of cardiac adrenomedullin in this model of hypertension.

Adrenomedullin↗
PubMed1996

Mitral valve operation after percutaneous transvenous mitral commissurotomy (PTMC): an evaluation of PTMC indications based on intraoperative findings.

Six patients underwent open heart surgery for mitral valve disease after percutaneous transvenous mitral commissurotomy (PTMC) because of recurrent mitral stenosis (MS) in 4, moderate mitral regurgitation (MR) in 1, and acute severe MR in 1. These 6 patients were the only such observed cases out of a total of 86 patients who presented with PTMC in our hospital between October 1989 and May 1995. The duration of the subjective symptoms related to heart failure was 24.1 +/- 11.6 years, ranging from 3 to 30 years. Four of the six patients had had a previous surgical commissurotomy [closed mitral commissurotomy (CMC) in 2 and open mitral commissurotomy (OMC) in 2] from 24 to 30 years earlier (mean 28 years). The intraoperative findings of the 4 with residual MS included severe thickening, calcification on anterior and posterior leaflets, and bilateral commissures. Five patients were noted to have shortening and adhesion in the mitral subvalvular apparatus. Two patients with moderate to severe tears on the anterior leaflets and another two patients with tears on the posterior leaflet were also noticed; however, these leaflets were not severely thickened. It was possible to split and repair the fused commissure in one patient, but the other five required MVR due to severe subvalvular lesions. Therefore, if a patient has bilateral commissural calcification or has less thickend leaflets with severe subvalvular thickening and fusion with a small MVA measuring less than 0.8 cm2 and a MS score of more than 8, the OMC procedure is considered to provide good long-term clinical results. The decision to perform either PTMC or OMC should only be made based on meticulous echo Doppler findings and a hemodynamic evaluation of the mitral valve.

Adult↗
PubMed1996

Extramedullary plasmacytoma of the jejunum.

A case of extramedullary plasmacytoma (EMP) of the jejunum, an uncommon neoplasia, is reported. A 56-year-old Japanese woman who experienced intermittent upper abdominal pain and weight loss had a large movable mass in the upper abdomen. The mass was hypervascular in an angiographic study and positive for gallium-67 citrate scintigraphy. Immunoelectrophoresis showed the presence of an M-component of immunoglobulin (Ig) A-lambda in the serum. It was identified as an EMP immunohistochemically positive for IgA-lambda. This M-component disappeared after resection and chemotherapy. The clinical features of this rare neoplastic disorder are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Adrenomedullin: changes in circulating and cardiac tissue concentration in Dahl salt-sensitive rats on a high-salt diet.

Adrenomedullin (AM), a novel hypotensive peptide, is suggested to be involved in defense mechanisms against hypertension, however, the detail mechanisms have not been clarified. To elucidate whether AM synthesis would be altered in a salt dependent hypertension, we have investigated the AM concentration and AM messenger RNA (mRNA) level in tissues of Dahl salt-sensitive rats on either low- or high-salt intake. The AM concentration in cardiac ventricle of the high-salt group was significantly higher than that of the low-salt group. The plasma AM concentration was also significantly higher in the high-salt group than in the low-salt group. Furthermore, the plasma AM concentration correlated well with the weight of left ventricle. RNA blot analysis revealed that the AM mRNA level in cardiac ventricle of the high-salt group was higher than that of the low-salt group. These results suggest that AM participates in the pathophysiology of salt dependent hypertension and plays a role in cardiac hypertrophy.

Adrenomedullin↗
PubMed1996

[Maze operation for chronic atrial fibrillation with valvular heart diseases].

Between July 1994 and August 1995, 14 patients underwent combined modified maze procedure and valvular surgery including 5 patients having reoperation. Associated procedures were performed with mitral valve operation (n = 13), tricuspid annuloplasty or valve replacement (n = 9) and aortic valve replacement (n = 4). Duration of atrial fibrillation (AF) varied from 1 to 18 years (mean 8.0 +/- 5.8 year), the f-wave voltage ranged from 0.05 to 0.5 mV (0.21 +/- 0.13 mV), left atrial dimension (LAD) ranged from 35.6 to 66.3 mm (49.0 +/- 9.3). One patient died 2 months after undergoing combined maze procedure and MVR + TAP due to pulmonary infection and sepsis, but the other 13 patients survived. Nine patients (69%) regained atrial rhythm, two patients (15%) had junctional rhythm and another two (15%) remained in AF at follow-up periods between 1 to 11.5 months (6.3 +/- 3.1). The nine patients who recovered to normal sinus rhythm had preoperative f-wave for a significant higher voltage than the patients with AF and JR (0.27 +/- 0.12 vs 0.13 +/- 0.05 mV, p < 0.05) and a smaller left atrial dimension (44.5 +/- 0.7 vs 54.8 +/- 6.9 mm, p < 0.05). These data suggest that the maze operation is effective and should be considered for patients with chronic AF indicated for surgical valvular diseases.

Adult↗
PubMed1996

Distribution and characterization of rat immunoreactive proadrenomedullin N-terminal 20 peptide (PAMP) and the augmented cardiac PAMP in spontaneously hypertensive rat.

Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide processed from an adrenomedullin precursor. In this study, high concentrations of immunoreactive PAMP (ir-PAMP) were detected in rat cardiac atrium and adrenal gland by the radioimmunoassay (RIA) for rat PAMP. The mean plasma concentration of rat ir-PAMP was 3.8 +/- 0.3 fmol/ml. Analysis in atrium, adrenal gland and plasma with high performance liquid chromatographies showed that most ir-PAMP emerged as one major peak at the position exactly identical to that of the authentic rat PAMP. We further investigated the tissue and plasma concentrations of rat ir-PAMP in spontaneously hypertensive rat (SHR) to elucidate the role of PAMP in hypertension. The ir-PAMP concentration in heart tissue of SHR was found to be increased compared with that of the control rat. Especially, the atrial concentration of ir-PAMP of SHR (5.66 +/- 0.78 fmol/mg wet tissue) was significantly higher than that of the control (3.29 +/- 0.22 fmol/mg wet tissue). Cardiac PAMP might have a role for the protection from systemic hypertension.

Adrenal Glands↗
PubMed1995

Augmented adrenomedullin concentrations in right ventricle and plasma of experimental pulmonary hypertension.

Adrenomedullin is a strong vasorelaxing peptide discovered in pheochromocytoma tissue. Monocrotaline, a pyrrolizidine alkaloid derived from Crotalaria spectabilis, is known to cause pulmonary hypertension. To test the hypothesis that adrenomedullin plays a role similar to that of atrial natriuretic peptide or brain natriuretic peptide in modulating right ventricular responses to pulmonary hypertension, we have compared concentrations of immunoreactive rat adrenomedullin and adrenomedullin messenger RNA levels in tissues of monocrotaline treated rats with those of control rats. We also measured the effect of pulmonary hypertension on plasma level of the peptide. The concentrations of adrenomedullin immunoreactivity in right ventricle and plasma were significantly higher in monocrotaline treated rats than in control rats. The messenger RNA level of adrenomedullin in right ventricle was also higher in monocrotaline treated rats than in control rats. These results suggest that adrenomedullin participates in the mechanism to counteract the high blood pressure in pulmonary circulation.

Adrenomedullin↗