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Biomedical subjects

N Yokoo

Publications and source records attributed to N Yokoo.

At least 19 recordsLinked to original sources
PubMed2001

Mixed medullary-papillary carcinoma of the thyroid with lymph node metastases: report of a case.

We report herein the case of a 77-year-old woman found to have mixed medullary-papillary carcinoma in the right thyroid with lymph node metastases 30 years after a left thyroidectomy. The preoperative values of serum calcitonin and carcinoembryonic antigen (CEA) were high, and fine-needle aspiration biopsy revealed class V, which led us to suspect papillary carcinoma. A right thyroidectomy with dissection of the right neck lymph nodes was performed. Histopathological examination of the tumor specimens revealed gradual borders between medullary carcinoma and papillary carcinoma with positive immunohistochemical staining to calcitonin, chromogranin A, CEA, and thyroglobulin. The serum levels of calcitonin and CEA decreased to normal after the operation. The point mutation of the RET proto-oncogene was found to be negative by a DNA analysis of the peripheral leukocytes. This cancer seemed not to be associated with multiple endocrine neoplasia type 2 syndrome. The presence of both medullary and papillary components in the thyroid with lymph node metastases is rare and may suggest that the tumor had arisen from a common stem cell.

Aged↗
PubMed2001

[Sedative premedication is necessary for infants in anesthetic induction under the presence of mother].

We examined the necessity of sedative premedication for elective operation of childhood when induction was performed beside the mother. One hundred and nine patients (aged from 2 to 8 years) were assigned randomly to two groups; midazolam (0.5 mg.kg-1, orally, n = 56) was administered 45 min before induction in Group M, and vehicle was administered (n = 53) in Group C. The differences between the two groups about their calmness and behavior were investigated using double blind method, and analyzed according to their ages, as infants (2 to 4 years), kindergarteners (5 to 6 years) and school children (7 to 8 years). The significantly higher incidences of agitation or alertness were observed in infants of Group C (P < 0.05) and all other patients were calm and well sedated. We conclude that sedative premedication is necessary in infants even if induction is performed beside patient's mothers.

Anesthesia, General↗
PubMed1999

Effectiveness of an inferior vena caval filter as a preventive measure against pulmonary thromboembolism after abdominal surgery.

In three patients with a previous history of pulmonary thromboembolism, inferior vena caval filters were inserted before elective laparotomies to prevent a recurrent pulmonary thromboembolism. Two patients had colon cancer and underwent colectomies, while the other had myoma uteri, which might have been the cause of deep vein thrombosis, and thus a hysterectomy was performed. In spite of their poor risks, their postoperative courses were fairly good owing to perioperative management including anticoagulant therapy, and no recurrence has been observed since the operation in every case. A pulmonary thromboembolism is a fatal complication which follows deep vein thromboses. In patients with such a previous history, the risk is much higher after a laparotomy because of long-term bed rest, hypercoagulability, and so on. The mortality rate after a recurrence of pulmonary thromboembolism is reported to reach 30% without adequate therapy, whereas it is reduced to 8% with anticoagulant therapy, and to 0.8% with additional inferior vena caval filter placement. Considering the feasibility of insertion and the low incidence of complications, preoperative inferior vena caval filter placement is thus recommended for patients having a previous history of either pulmonary thromboembolism or deep vein thrombosis.

Aged↗
PubMed1998

Cataract surgery in a patient with severe chronic iritis and corneal endothelial damage.

We report a patient with broad anterior synechias and corneal endothelial damage. The patient had chronic iritis and cataracts secondary to chronic iritis in both eyes. Because the right eye had broad anterior synechias and severe corneal endothelial damage, extracapsular cataract extraction and intraocular lens implantation were performed through the basal iris. Good postoperative visual acuity was obtained. The cornea showed little trauma from the surgery and remained clear 36 months postoperatively.

Cataract↗
PubMed1997

Pharmacological profile of a novel synthetic inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase.

Pharmacological properties of NK-104 ((+)-monocalcium bis¿(3R,5S,6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)-3-quinolyl++ +]-3,5-dihydroxy-6- heptenoate¿, CAS 147526-32-7), a novel synthetic inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, were investigated. The kinetic study, using rat liver microsomal HMG-CoA reductase, revealed that NK-104 is a competitive inhibitor of HMG-CoA reductase with a Ki of 1.7 nmol/l. To examine the inhibitory effect on sterol synthesis in vivo, de novo synthesis of sterols from [14C]acetate 3 h after oral administration of NK-104 was measured in rats. NK-104 showed marked inhibition in liver (ED50 0.13 mg/kg) and in ileum (ED50 0.20 mg/kg), but much weaker in the other tissues. The inhibitory effect of NK-104 on liver sterol synthesis lasted over 6 h, while that of pravastatin and simvastatin disappeared 6 h after administration of the drugs twice the ED50s. Due to induction of HMG-CoA reductase, initial suppression of hepatic sterol synthesis by pravastatin and simvastatin was compensated, and the cumulative change in hepatic sterol synthesis during 12 h after drug administration was remarkably negative only with long-acting NK-104. Hypolipidemic effects of NK-104 (0.03, 0.1, 0.3 and 1 mg/kg p.o. for 2 weeks) were examined in beagle dogs. NK-104 reduced plasma total cholesterol dose-dependently (13.1, 18.5 and 20.2% at doses of 0.1, 0.3 and 1 mg/kg, respectively), and also plasma triglycerides by 0.1 mg/kg or more. Pravastatin (1 and 3 mg/kg) and simvastatin (3 mg/kg) lowered plasma total cholesterol (14.0, 15.4 and 17.4%, respectively), but did not significantly affect plasma triglyceride levels. These results indicate that NK-104 is a potent, liver-selective, long-acting HMG-CoA reductase inhibitor with a high cholesterol- and triglyceride-lowering potency.

Animals↗
PubMed1992

Antitumor activity of Toxoplasma lysate antigen against methylcholanthrene-induced tumor-bearing rats.

Growth of the tumor autoinduced by 20-methylcholanthrene (MC) in rats was inhibited after administration of Toxoplasma lysate antigen (TLA). The antitumor activity of TLA was most obvious in the early stage of tumoral growth. When TLA was administered to rats before the appearance of tumour, tumor formation was delayed slightly. Histopathological studies revealed dense growths of spindle tumor cells in untreated control rat, while enlarged central necrosis with the infiltration of lymphocytes and neutrophils was apparent in TLA-treated rats. According to the immunohistological examination of tumor tissue with anti-Thy-1 antibody, the rats treated with TLA showed large Thy-1 positive granular cells, whereas the untreated rats indicated only a few small Thy-1 positive cells. These observations indicate that TLA is a useful modifier of biological responses to MC-induced tumors.

Animals↗
PubMed1988

Changes in concentrations of respiratory components and cytochrome oxidase activity in mitochondria obtained from carbon tetrachloride-induced cirrhotic rat liver.

1. Changes in the concentrations of respiratory components, phosphorylative activity, the cytochrome oxidase activity of mitochondria and the hepatic adenylate energy charge level (in situ) were studied in cirrhotic rat liver induced by carbon tetrachloride (CCl4). 2. In the cirrhotic liver mitochondria, concentrations of cytochrome a(+a3), cytochrome b, coenzyme Q9 and coenzyme Q10 increased significantly to 2.44 +/- 0.02 x 10(-10) (mean +/- SE), 1.37 +/- 0.05 x 10(-10), 25.57 +/- 0.47 x 10(-10) and 5.39 +/- 0.26 x 10(-10) mol/mg of mitochondrial protein, respectively, compared with 1.83 +/- 0.03 x 10(-10), 1.22 +/- 0.02 x 10(-10), 16.24 +/- 0.39 x 10(-10) and 1.81 +/- 0.07 x 10(-10) in normal rats [P less than 0.001 for cytochrome a(+a3), coenzyme Q9 and coenzyme Q10, and P less than 0.01 for cytochrome b]. 3. Concentrations of flavoprotein and pyridine nucleotides decreased significantly to 13.33 +/- 0.14 x 10(-10) and 45.68 +/- 1.59 x 10(-10) mol/mg of mitochondrial protein, respectively, compared with 14.79 +/- 0.33 x 10(-10) and 86.26 +/- 1.83 x 10(-10) in normal rats (P less than 0.001). There was no significant difference in the concentration of cytochrome c(+c1). 4. Cytochrome oxidase activity per unit of cytochrome a(+a3) increased significantly to 67.43 +/- 1.71 atoms O s-1 mol-1, compared with 55.77 +/- 1.16 in normal rats (P less than 0.001). By contrast, phosphorylative activity per unit of cytochrome a(+a3) decreased significantly in the cirrhotic liver to 10.40 +/- 0.36 s-1 compared with 13.43 +/- 0.49 in normal rats (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1988

Changes in energy metabolism of allografts after liver transplantation.

To evaluate the function of energy metabolism in allografts after liver transplantation, changes in hepatic energy charge levels, oxidative and phosphorylative activities of mitochondria and arterial blood ketone body ratio (acetoacetate/3-hydroxybutyrate; KBR) were studied in piglets. Hepatic energy charge levels decreased to 0.831 +/- 0.010 at 3 days and 0.836 +/- 0.009 at 3 weeks after operation compared to the preoperative value of 0.868 +/- 0.006 (p less than 0.01), and returned to 0.856 +/- 0.007 at 6 weeks. Mitochondrial oxidative and phosphorylative activities were moderately enhanced to 19.14 +/- 2.07 (10(-10) mol ATP/mg of mitochondrial protein/s) at 3 days and 20.89 +/- 1.72 at 3 weeks compared to the preoperative value of 16.74 +/- 2.36, and returned to 16.65 +/- 1.54 at 6 weeks. There was no significant difference in the concentrations of mitochondrial respiratory components, except in cytochrome c + c1. KBR decreased immediately at the beginning of the anhepatic phase and rapidly recovered to the preoperative level within 60 min after revascularization of allografts. There was no change in KBR during the postoperative course except in cases with clinical deterioration. From these results, it is suggested that the mitochondrial capacity for ATP synthesis was enhanced to compensate for the decreased energy charge level and that a decreased KBR is a sign of a critically deranged metabolic function in allografts.

Adenosine Triphosphate↗
PubMed1988

Effects of partial ischemia and reflow on mitochondrial metabolism in rat liver.

To clarify the effects of partial ischemia and reflow on the mitochondrial metabolism of the rat liver, the afferent vessels supplying the left lateral and left half of medial lobes were occluded and then reperfused after given time periods of ischemia (30, 60, 90 and 120 min, groups A, B, C and D, respectively). Samplings were taken at 0, 10 and 60 min after reperfusion. The energy charge levels of ischemic lobes decreased rapidly from 0.85 +/- 0.01 in the sham group to 0.38 +/- 0.11, 0.35 +/- 0.07 and 0.34 +/- 0.06 in groups B, C and D, respectively. The phosphorylative activities of mitochondria isolated from ischemic lobes decreased gradually along with the time of ischemia. The reversal of mitochondrial function and energy charge levels following reperfusion was noted in groups A and B. In nonischemic lobes, the phosphorylation rate (nmol ATP/mg/min) increased from 90 +/- 6 in sham group to 125 +/- 12 and 130 +/- 9; 131 +/- 5 and 130 +/- 6; 123 +/- 6 and 122 +/- 17, and 138 +/- 6 and 138 +/- 13 at 10 and 60 min after reflow in groups A, B, C and D, respectively (p less than 0.05). The energy charge level of nonischemic lobes decreased from 0.85 +/- 0.01 of sham group to 0.80 +/- 0.03 in group D (p less than 0.05). From these results, it is concluded that the transitional zone for the reversal of mitochondria function and energy metabolism following prolonged liver ischemia appears at around 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1987

Short-term changes in blood ketone body ratio in the phase immediately after liver transplantation.

Arterial blood ketone body ratio was measured after orthotopic liver transplantation in piglets. Ketone body ratio immediately decreased at the beginning of the anhepatic phase and was rapidly restored to the normal levels within 30 min after the revascularization of the allograft. Serum lactate and pyruvate levels increased in anhepatic phase and gradually decreased after revascularization. Changes in the lactate and pyruvate levels were always preceded by changes in ketone body ratio. In the case of transplantation after 12-hr-preservation of the allograft, ketone body ratio failed to maintain normal levels after transplantation, resulting in a high mortality. It is suggested that the elevation of decreased ketone body ratio is prerequisite for the normalization of the deranged metabolic state after liver transplantation, and that ketone body ratio provides an accurate means to assess the initial metabolic function of the allograft.

Animals↗
PubMed1986

Effect of hepatic artery embolization on the adenylate energy charge level and the redox state of the cirrhotic liver.

Hepatic energy charge ((ATP + 1/2ADP)/(ATP + ADP + AMP)) and arterial blood ketone body ratio (acetoacetate/3-hydroxybutyrate) were measured after hepatic artery embolization in carbon-tetrachloride-induced cirrhotic rats. In normal livers, energy charge slightly decreased at 3 h and returned to normal levels at 6 h. By contrast, in cirrhotic livers, energy charge was drastically decreased at 3 h after embolization and was not completely recovered at 6 h. Blood ketone body ratio, reflecting hepatic mitochondrial redox (NAD+/NADH) state, also decreased at 3 h after embolization in both groups, and its recovery was not observed in cirrhotic group at 6 h.

Adenine Nucleotides↗
PubMed1986

Changes in oxidative phosphorylation, adenylate energy charge, and respiratory components in chloramphenicol-treated regenerating rat liver.

To clarify the functional adaptability of mitochondria in the regenerating liver, the concentrations of respiratory components, hepatic energy charge levels, cytochrome oxidase activity, and phosphorylative activity were studied in mitochondria obtained from regenerating liver of rats treated with chloramphenicol (CAP). In the hepatectomized groups with CAP treatment, a dose-dependent decrease occurred in the concentrations of cytochrome a(+ a3), cytochrome b, cytochrome c + c1, flavoprotein, and pyridine nucleotide. Cytochrome oxidase activity and phosphorylative activity per milligram of mitochondrial protein also decreased dose dependently in CAP-treated hepatectomized groups, with a significant increase in these values per unit of cytochrome a(+ a3). Hepatic energy charge levels significantly decreased in the hepatectomized groups. However, no significant differences were seen among the hepatectomized groups. However, no significant differences were seen among the hepatectomized groups with or without CAP treatment. Our results suggest that hepatic energy charge is maintained at the same relative level by a compensatory enhancement in phosphorylative capacity associated with cytochrome oxidase activity per unit of cytochrome a(+ a3), in spite of a remarkable decrease in the concentrations of respiratory components.

Adaptation, Physiological↗
PubMed1985

Changes in coenzyme Q level in mitochondria of cirrhotic rat liver.

In the cirrhotic rat liver induced by carbon tetrachloride and phenobarbitone, the concentrations of mitochondrial Coenzyme Q were measured in comparison with other respiratory components. The concentration of cytochrome a(+a3) and Coenzyme Q significantly increased in the cirrhotic liver, without any changes in the ratio of Coenzyme Q to cytochrome a(+a3). It is suggested that such increase of Coenzyme Q plays an important role as one of the adaptive responses to compensate for the prolonged metabolic overload on the mitochondrial respiratory assembly. Also, from the findings that the concentrations of cytochrome a(+a3) in the mitochondria of cirrhotic liver increase concomitant with the severity of cirrhosis, it is suggested that the rise of Coenzyme Q levels may be one of the indicators for the decreased functional reserve capacity in liver cirrhosis.

Animals↗
PubMed1985

Promoting effect of the new chymotrypsin inhibitor FK-448 on the intestinal absorption of insulin in rats and dogs.

FK-448 is a potent and specific inhibitor of chymotrypsin, which enhances the intestinal absorption of insulin in rats and dogs resulting in a decrease in blood glucose levels in these animals. In dogs, the immunoreactive insulin (IRI) level of plasma rose proportionally to the decrease in blood glucose level. From in-vitro data, insulin was inactivated by pancreatic enzymes or the supernatants of intestine or liver homogenates. FK-448 suppressed the digestion of insulin by pancreatic enzymes and its enhancement of the intestinal absorption of insulin was found to be related to its inhibition of digestive enzymes, especially chymotrypsin.

Animals↗