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Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 145 records · Page 8Linked to original sources
PubMed2001

Increases in plasma ACTH and cortisol after hypertonic saline infusion in patients with central diabetes insipidus.

To clarify the mechanism for the potentiation of CRH-induced ACTH response by the infusion of hypertonic saline, we investigated changes in plasma ACTH concentration after infusion of 5% hypertonic saline in five patients with untreated central diabetes insipidus (DI). Basal levels of plasma ACTH and cortisol in the DI group were not significantly different from those in normal control subjects. The infusion of hypertonic saline produced an increase in plasma arginine vasopressin (AVP) in controls, but did not elevate ACTH. However, in patients with DI, the plasma AVP concentration did not change, but circulating ACTH increased 3.6-fold (7.7 +/- 1.5 to 23.0 +/- 2.7 pmol/liter; P < 0.01), and plasma cortisol also increased significantly (298 +/- 99 to 538 +/- 124 nmol/liter; P < 0.05). Moreover, a positive correlation was observed between plasma ACTH and osmolality (r = 0.72; P < 0.005). These results indicate that ACTH secretion in DI patients is regulated by a mechanism distinct from that in healthy subjects. It seems possible that the increase in plasma osmolality promotes ACTH secretion in DI patients through AVP and/or urocortin via the hypophyseal portal system, independent of the AVP secretion from magnocellular neurons.

Adrenocorticotropic Hormone↗
PubMed2001

Localization of cellubrevin-related peptide, endobrevin, in the early endosome in pancreatic beta cells and its physiological function in exo-endocytosis of secretory granules.

Cellubrevins are integral membrane proteins expressed in a wide variety of tissues and usually localized in recycling vesicles. Here, we investigated the cellular localization of a cellubrevin-related peptide, endobrevin, in pancreatic (beta) cells and its implication in the exo-endocytosis of insulin and (gamma)-amino butyric acid (GABA). Immunocytochemistry showed that endobrevin is associated with tubulo-vesicular structures, which are colocalized with early endosomes labeled by early endosome antigen (EEA)-1 in insulinoma MIN6 cells. To determine the cellular localization of endobrevin, we appended the green fluorescent protein (GFP) to endobrevin and the fusion protein was introduced into MIN6 cells. The subcellular localization of GFP-endobrevin was visualized by confocal laser microscopy. Colocalization study based on the expressed GFP-endobrevin and endocytosed Texas-Red(Tx-R) labeled transferrin receptor and immunocytochemistry with anti-EEA1 antibody revealed that endobrevin was preferentially localized in the early endosome. Then, we examined the functional role of endobrevin in the exocytosis of insulin and GABA from pancreatic (beta) cells. Endobrevin overexpression increased the amount of GABA released from MIN6 cells; in contrast, it decreased the glucose-stimulated insulin release from rat islets, MIN6 and INS1-D cells to approximately 50% of the control levels. Both in vitro and in vivo binding studies showed that endobrevin binds to syntaxin 1. Finally, using the fluorescent probe FM4-64, it was revealed that endobrevin overexpression accelerates vesicle recycling. We conclude that (1) endobrevin is localized in the early endosome in pancreatic (beta) cells and (2) endobrevin plays a physiological role in the exo-endocytosis of insulin and GABA from pancreatic (beta) cells, probably via an interaction between endocytic vesicles and the endosome.

Animals↗
PubMed2001

Co2(CO)8-mediated endo mode cyclization of epoxy-alcohol: synthesis of 2-ethynyl-3-hydroxy-2-methyltetrahydropyran and 2-ethynyl-3-hydroxy-3-methyltetrahydropyran derivatives.

Successive treatment of 4,5-epoxy-5-methyl-7-trimethylsilyl-6-heptyne-1-ol with Co2(CO)8 at 0 degrees C and a catalytic amount of BF3 x OEt2 at -78 degrees C gave the tetrahydropyran derivatives with the cobalt-complexed moiety. Similarly 4,5-epoxy-4-methyl-7-trimethylsilyl-6-heptyne-1-ol underwent ring closure under the above conditions to provide the corresponding tetrahydropyran derivatives. The preferential endo mode cyclization over the exo one was observed in these experiments.

Alkynes↗
PubMed2001

Expanded-bed protein refolding using a solid-phase artificial chaperone.

An efficient solid-phase protein refolding method based on artificial chaperone-assisted refolding is proposed. The method employs insoluble cyclodextrin polymer beads and the expanded-bed technique. Alpha-glucosidase, whose spontaneous refolding yield from a urea-denatured state is up to 30% at a protein concentration of up to 10 microg/ml, could be refolded with a yield that was improved more than two-fold at a protein concentration more than five-fold higher when protein solution was circulated through an expanded bed under optimized conditions. Unlike the conventional liquid-phase artificial system, further steps to purify the refolded product, which are generally needed to remove detergent-cyclodextrin complex and excess cyclodextrin, were unnecessary. In addition, the polymer beads were reusable after simple washing with water, and the continuous system is suitable for easy-scale-up using commercially available devices. This new method is considered to be a powerful means of achieving large-scale protein refolding for industrial protein production.

Journal Article↗
PubMed2001

Voltammetric studies of antimony ions in soda-lime-silica glass melts up to 1873 K.

The half wave potential of reduction of Sb5+ in 16Na2O x 10CaO x 74SiO2 glass melts was examined by differential pulse voltammetry up to 1873 K. The half wave potential shifted to the positive direction with an increase in temperature. The results indicate that the equilibrium of Sb5+/Sb3+ shifted to negative direction with an increase in temperature. The half wave potential shifted to positive direction (48 mV at 1473 K) when the atmosphere over the melts changed from pure oxygen gas to air, in agreement with the theoretical prediction. The reversibility of Pt:O2 reference electrode is confirmed.

Journal Article↗
PubMed2001

[Anesthetic experience of emergency coronary artery bypass graft operation in a patient with cardioamyloidosis].

A 76-year-old woman with acute myocardial infarction underwent an emergency coronary artery bypass graft operation. She developed cardiac failure and sick sinus syndrome before the surgery because she was with cardioamyloidosis. Therefore, intra-aortic balloon pumping and the pacemaker were used to maintain the hemodynamics prior to the operation. Anesthesia was induced with midazolam 5 mg, morphine 30 mg and pancuronium 5 mg, and maintained with 0.3-0.5% isoflurane in 50% nitrous oxide and 50% oxygen. Morphine 10 mg was also injected during the surgery, and the total dose of morphine 40 mg was administered. The pacemaker at 80 bpm was inserted and mexiletine 0.5 mg.kg-1.h-1 was given to prevent ventricular arrhythmias at weaning from cardio-pulmonary bypass. The surgical operation was successfully performed and the postoperative course was uneventful. A combination of light inhalation anesthesia with narcotics may be a choice for anesthetic management of patients with cardioamyloidosis as this method has less influence on hemodynamics.

Aged↗
PubMed2001

Ideomotor apraxia in patients with Alzheimer disease: why do they use their body parts as objects?

OBJECTIVE: Difficulty in pantomiming the use of tools is observed in patients with Alzheimer disease. Patients with Alzheimer disease tend to use their body parts as objects when they try to pantomime the use of tools. The body-parts-as-objects phenomenon was thought to consist of appropriate gross movement of patients' arms despite inappropriate patterns of handling tools with their hands. However, the mechanism has not been investigated fully. METHODS: The authors examined 11 healthy individuals and 24 patients with Alzheimer disease for ability to recognize tools, to pantomime the use of tools, to use actual tools, and to select an appropriate photograph of a handling pattern of the tool. RESULTS: In comparison with the patients with Alzheimer disease, the healthy individuals had higher scores for all tasks. The authors classified the patients into group A (patients with higher pantomime scores), group B (patients with middle level scores), and group C (patients with lower scores). Frequency of use of body parts as objects for patients in group B was higher than that of patients in group A and in group C. The mean Mini-Mental State Examination score for patients in group A was higher than that of patients in group B and in group C. In comparison with patients in group A, patients in group B showed lower scores on the hand-posture discrimination task without a tool, even after controlling the Mini-Mental State Examination score. CONCLUSIONS: The authors conclude that body-parts-as-objects responses in patients with Alzheimer disease occur because general cognition is lowered or because retrieval ability of the appropriate holding posture for tools is impaired.

Aged↗
PubMed2001

Early stage of urolithiasis formation in experimental hyperparathyroidism.

PURPOSE: We have previously noted marked acceleration in the proliferative activity of parathyroid cells in rats with spontaneous hypercholesterolemia and secondary hyperparathyroidism. Using this proliferative potential we investigated whether transplantation of these enlarged parathyroids into normal rats would induce hyperparathyroidism and renal stones. MATERIALS AND METHODS: We used 26-week-old male rats with spontaneous hypercholesterolemia as donors, and 5-week-old normal male Sprague-Dawley rats and rats with spontaneous hypercholesterolemia as recipients. Enlarged parathyroid glands were transplanted into group 1--Sprague-Dawley rats with no treatment, group 2--Sprague-Dawley rats that received FK-506 as an immuno-suppressor, group 3--rats with spontaneous hypercholesterolemia rats that underwent parathyroidectomy plus FK-506 administration and group 4--Sprague-Dawley rats that underwent parathyroidectomy plus FK-506 administration. Parathyroidectomy was performed in recipients before transplantation to ensure a low calcium condition. RESULTS: Grafts were rejected within 11 and 15 weeks in groups 1 and 2, respectively. In group 3, 78% of the grafts were successful even after 19 weeks. In group 4 graft survival was 30% at 15 weeks with complete rejection at 19 weeks. In group 3 gradually elevated serum parathyroid hormone was observed as well as stone plaques containing calcium oxalate and calcium phosphate in renal tubules located mainly in the corticomedullary junction. An increased number of plaques was associated with higher parathyroid hormone. CONCLUSIONS: Our study shows that transplanted parathyroid glands function with an immunosuppressive agent and the maintenance of hypocalcemic conditions, and they secrete sufficient parathyroid hormone to demonstrate hyperparathyroidism. Plaque in these kidneys indicates an early stage of urolithiasis caused by hyperparathyroidism.

Animals↗
PubMed2001

[Acute disseminated encephalomyelitis in a 3-month-old infant].

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease showing multifocal central nervous system lesions due to an autoimmune disorder. We reported a 3-month-old girl with ADEM. One week after having a cold, she presented with somnolence, poor feeding and vomiting. When she was admitted three days after the onset, she could neither fix or follow objects with her eyes nor respond to sound. Her muscle tone was decreased. Cerebrospinal fluid examination revealed pleocytosis, elevated protein concentration and positive myelin basic protein. No oligoclonal band was detected. Diffuse monomorphic slow wave activity was noted on the electroencephalogram. Only wave I was present bilaterally on the auditory brainstem response. T2 weighted images of magnetic resonance imaging revealed multiple areas of high signal in the right posterior limb of the internal capsule, white matter of the cerebellum and brainstem. She was diagnosed as having ADEM, and underwent high dose gamma-globulin therapy. Corticosteroids were not given because of her high blood pressure. The clinical symptoms improved continuously before and after the administration. Two years after the onset, she showed normal growth and development without reoccurrence. The age at onset of childhood ADEM is usually 3 or 4 years. ADEM before one year of age is very rare. The demyelinating lesions of this case corresponded to the regions which normally become myelinated by 3 months. Although ADEM is usually treated with corticosteroids, high dose gamma 1-globulin therapy can be considered if patients are very young or have a high risk for corticosteroid, or respond poorly to corticosteroids.

Drug Administration Schedule↗
PubMed2001

[Anesthetic management of two patients with essential thrombocythemia].

We report different methods of anesthetic management in two patients with essential thrombocythemia. Case 1 is a 69-year-old male scheduled for cholecystectomy. His blood platelet counts were maintained between 10 to 40 x 10(4).microliters-1 after myelosuppression therapy. His preoperative blood tests were within normal limits. Since he had no signs of hemorrhage or thrombus preoperatively, an epidural catheter was inserted for intraoperative analgesia and postoperative pain relief. Anesthesia was induced with propofol and fentanyl, and maintained with N2O-O2-sevoflurane. Mepivacaine 1% was injected through the epidural catheter for intraoperative analgesia and buprenorphine was injected through the catheter for postoperative pain relief. His perioperative course was uneventful. Case 2 is an 88-year-old female scheduled for emergency enterectomy. She had had recurrent bouts of thrombosis. Her blood platelet counts were 89.1 x 10(4).microliters-1. Since her preoperative management of thrombocythemia had been poor, epidural anesthesia was not performed. Anesthesia was induced with propofol, and maintained with N2O-O2-sevoflurane. Her perioperative course was uneventful. We conclude that spinal or epidural anesthesia is not contraindicated when preoperative platelet counts and aggregation test are within normal limits in a patient with essential thrombocythemia.

Aged↗
PubMed2001

[Prophylactic effect of pirarubicin (THP) on postoperative recurrence of superficial bladder cancer in terms of intravesical retention time].

In order to determine the modality of prophylactic intravesical instillation of pirarubicin (THP = tetrahydropyranyladriamycin) following transurethral resection (TUR) of superficial bladder cancer, a prospective randomized study was performed. A total of 79 patients were randomized into "2-hour instillation" (A), "5-min instillation" (B) and "control" (C) groups. Prophylactic efficacy and side effects were analyzed in each group. In groups A and B, 20 mg of THP was first dissolved in 10 ml of distilled water, adjusted to 40 ml with saline and was administered intravesically once a week for 10 weeks, starting from 1 week after TUR. The recurrence-free rate was calculated in 65 evaluable patients. The one-year recurrence-free rate was 70.2% in group A, 62.8% in group B and 52.1% in group C. The one-year recurrence-free rate was significantly higher in group A than in group C. Adverse effects were observed in 21.4% of the patients in group A and 40.7% in group B. There was no significant difference in the occurrence rate of side effects between these two groups. Taking the prophylactic efficacy and side effects into consideration, "2-hour instillation" seemed to be better than "5-min instillation".

Administration, Intravesical↗
PubMed2001

[Anesthetic management of a patient with congenital antithrombin III Deficiency using temporal inferior vena cava filter].

We described the perioperative management of a patient with congenital antithrombin III deficiency using temporal inferior vena cava filter. A 30-year-old man with congenital antithrombin III deficiency was scheduled for artificial head replacement of the hip joint under general anesthesia. He was diagnosed as having congenital antithrombin III deficiency when he had had an episode of venous thrombosis after artificial head replacement of the right hip joint. He had been taking warfarin as an anticoagulant, and it was discontinued three days before surgery. To prevent perioperative thrombus formation, the plasma AT III activity was maintained above 80% before, during and after surgery using AT III concentrates. We also placed the temporal inferior vena cava filter. There was no serious thrombosis or embolism perioperatively. The use of the filter during the perioperative period helped to avoid development of serious thrombosis and embolism.

Adult↗