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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 109 records · Page 6Linked to original sources
PubMed1997

Modulation of [3H]dopamine release by neuropeptide Y in rat striatal slices.

Neuropeptide Y, a 36-amino-acid peptide, has a wide and specific distribution in the central nervous system. In this study we examined the regulatory mechanisms of neuropeptide Y on dopamine release in the rat central nervous system. The effects of neuropeptide Y on the electrically stimulated [3H]dopamine release were investigated in superfused striatal slices of Sprague-Dawley rats, spontaneously hypertensive rats and Wistar-Kyoto rats. Neuropeptide Y (1 x 10(-8) - 1 x 10(-7) mol/1) reduced the stimulation (1 Hz)-induced [3H]dopamine release by a comparable amount in Sprague-Dawley rats. The blockade of dopamine D2 receptors by the dopamine D2 receptor antagonist, sulpiride, diminished the inhibitory effects of neuropeptide Y on the stimulation-evoked [3H]dopamine release. Pretreatment of slices with pertussis toxin (a potent inhibitor of G1-proteins) attenuated the suppression of the stimulation-evoked [3H]dopamine release by neuropeptide Y. Unlabelled dopamine itself reduced the stimulation-evoked [3H]dopamine release, and the inhibitory effect was also attenuated in the pertussis toxin-pretreated slices. In spontaneously hypertensive rats, the inhibitory effect of neuropeptide Y on the stimulation-evoked [3H]dopamine release was more pronounced than that in Wistar-Kyoto rats. The results of the present study showed that neuropeptide Y inhibited the stimulation-evoked dopamine release partially mediated by dopamine D2 receptors and the pertussis toxin-sensitive G1-proteins in rat striatum. Furthermore, the greater effect of neuropeptide Y on dopamine release in spontaneously hypertensive rats suggests a possible involvement of the peptide in regulating the central dopaminergic nerve activity in hypertension.

Animals↗
PubMed1997

Nisoldipine blocks the increase of intracellular free calcium-ion concentration associated with elevated sodium-lithium countertransport activity in erythrocytes in patients with NIDDM.

To understand the mechanism by which elevated sodium-lithium countertransport activity (SLC) associates with increased intracellular free calcium-ion concentration ([Ca2+]i), we investigated the relationship between SLC and the effects of the extracellular Ca2+ concentration ([Ca2+]o) and a Ca2(+)-channel blocker, nisoldipine, on [Ca2+]i in erythrocytes from 48 patients with non-insulin-dependent (Type 2) diabetes mellitus (NIDDM). There was a significant correlation between SLC and [Ca2+]i. Nisoldipine in the incubation medium significantly decreased [Ca2+]i, and there was a significant positive correlation between SLC and the degree of [Ca2+]i decrease. When the [Ca2+]o was elevated, [Ca2+]i was significantly increased, but nisoldipine almost completely suppressed this increase of [Ca2+]i. There was a significant positive correlation between SLC and the degree of the suppression. These data suggest that elevated SLC correlates with increased [Ca2+]i, and that the increased [Ca2i]i might be due to the increased Ca2+ influx through a dihydropyridine-sensitive Ca2+ pathway.

Adult↗
PubMed1997

Ag(I)-N bond-containing compound showing wide spectra in effective antimicrobial activities: polymeric silver(I) imidazolate.

A neutral, Ag(I)-N bonding compound, polymeric silver(I)-imidazolate [Ag(imd)]n (1) consisting of Ag+: imd = 1:1 (Himd = imidazole, C3H4N2), showed wide spectra in effective antimicrobial activities against bacteria, yeast and mold. Of particular note are the activities against a wide range of mold. This polymeric solid does not crystallize and is sparingly soluble in all solvents. The monomeric, cationic, water-soluble Ag(I)-N bonding complex, [Ag(Himd)2](NO3) (2), has also shown wide spectra of effective antimicrobial activities. These activities observed here were significantly different from those of the recently prepared oligomeric Ag(I)-S bonding complexes; the latter have shown narrow spectra. It is proposed that the Ag(I)-N bonding is one of the key factors showing the wide spectra of antimicrobial activities and the potential targets for inhibition of bacteria and yeast by these Ag(I) complexes are proteins, but not nucleic acids. The physico-chemical properties of (1), in comparison with those of (2), with various measurements (FT-IR, Laser Raman scattering spectroscopy, ESCA and solid 13C CP-MAS NMR spectroscopies) are described.

Anti-Bacterial Agents↗
PubMed1997

The role of sodium-potassium adenosine triphosphatase in the regulation of membrane fluidity of erythrocytes in spontaneously hypertensive rats: an electron paramagnetic resonance investigation.

To determine a possible role of sodium-potassium adenosine triphosphatase (Na+, K+-ATPase) in the regulation of membrane functions in hypertension, we investigated the effects of ouabain on the membrane fluidity of erythrocytes in spontaneously hypertensive rats (SHR) by means of an electron paramagnetic resonance (EPR) and spin labeling method. Erythrocytes obtained from SHR were examined compared with age matched Wistar-Kyoto (WKY) rats, and the EPR spectra for 5-nitroxide stearate incorporated into the erythrocyte membranes were studied. The value of order parameter (S) of the EPR spectra was significantly higher in the erythrocytes of SHR than in the erythrocytes of WKY rats (S value: SHR, 0.721+/-0.009, n = 10; WKY, 0.652+/-0.008, n = 10; P < .05). The finding shows that the membrane fluidity of erythrocytes was lower in SHR than in WKY rats. Ouabain loading to erythrocytes significantly decreased the membrane fluidity (S value was increased) in both SHR and WKY rats. The ouabain induced change was significantly greater in SHR than in WKY rats. These results demonstrate that the membrane fluidity of erythrocytes might be highly dependent on the Na+, K+-ATPase activity in SHR, which would suggest an abnormality in Na+ related cellular functions in hypertension.

Animals↗
PubMed1997

Superparamagnetic iron oxide enhanced magnetic resonance imaging of rat liver with hepatocellular carcinoma and benign hyperplastic nodule.

RATIONALE AND OBJECTIVES: The authors assess the potential of a new superparamagnetic iron oxide (SPIO) in grading hepatocellular carcinoma (HCC) histologically and in differentiating HCC from benign hyperplastic nodule (HPN). METHODS: Nine Wistar rats (with poorly to moderately differentiated HCC, well-differentiated HCC, and HPN) received drinking water containing N-nitrosomorpholine, and were examined by magnetic resonance imaging (4.7 tesla). Spin-echo images (repetition time/echo time, 600/24.5 mseconds) were obtained before and 15 minutes after intravenous administration of 10 mumol Fe/kg of SH U 555A. RESULTS: Poorly to moderately differentiated and well-differentiated HCC showed no significant change in signal-to-noise ratio (SNR) 15 minutes after contrast, whereas HPN showed a significant decrease in SNR. The contrast-to-noise ratio (CNR) between each kind of tumor and adjacent liver parenchyma showed a significant increase at 15 minutes after contrast. CONCLUSIONS: The SPIO discussed in this article may help to differentiate HCC from HPN, but it remains difficult to grade hepatocellular carcinoma histologically.

Animals↗
PubMed1997

One-stage reconstruction of established facial paralysis using a rectus abdominis muscle transfer.

A free vascularized rectus abdominis muscle graft with a long motor nerve was used for reconstruction of unilateral established facial paralysis in one stage. Regarding the procedure, the pedicle vessels were anastomosed to the recipient vessels in the ipsilateral face, and the motor nerve of the muscle was sutured to the contralateral facial nerve. The advantages of using the rectus abdominis muscle are as follows: (1) the muscle is very thin, not bulky, (2) the muscle can be split easily to reduce the volume, (3) the intercostal nerve is long enough (more than 20 cm) to reach the contralateral facial nerve for suturing, (4) the pedicle vessels are large and long, (5) it is possible to carry out simultaneous operations with two teams, and (6) the donor-site morbidity is minimal. The disadvantages of this method are that complicated surgical dissection is required to obtain a motor nerve and that a postoperative abdominal hernia may occur.

Adolescent↗
PubMed1997

Relationship between cellular ATP content and cellular functions of primary cultured rat hepatocytes in hypoxia.

The importance of oxygen in maintaining the functional integrity of hepatocytes has been well established in a variety of experimental models, such as in vivo, perfused liver and isolated hepatocytes. However, one of the shortcomings of these systems is their short life span. Therefore, we have examined the effects of long-term hypoxia on cellular adenine nucleotide content and cellular functions, such as albumin production, urea production and DNA synthesis, in adult rat hepatocytes in primary culture. Hepatocytes were cultured at a density of 11 x 10(4) and 5 x 10(4) cells/0.18 mL per cm2 for the study of albumin and urea production and DNA synthesis, respectively, at various oxygen tensions (20, 12, 8 and 5%) for 24 h. Cellular ATP content in cultured hepatocytes in hypoxia gradually declined, corresponding to the decrease in oxygen tension, and the cellular ATP level at 5% oxygen was approximately 20% of that at 20% oxygen. Albumin production also decreased in parallel with the decrease in cellular ATP content in cultured hepatocytes in hypoxia. However, even when cellular ATP content gradually declined corresponding with the decrease in oxygen tension in cultured hepatocytes in hypoxia, such as at 8 or 5% oxygen, urea production remained at a high level; in contrast, DNA synthesis was completely suppressed. These results suggest that the cellular ATP content decreases in cultured hepatocytes during long-term hypoxia in relation to oxygen tension and that the relationship between decreased ATP levels and liver function in cultured hepatocytes during hypoxia differs for albumin production, urea production and DNA synthesis.

Adenine Nucleotides↗
PubMed1997

Passive immunization against dental plaque formation in humans: effect of a mouth rinse containing egg yolk antibodies (IgY) specific to Streptococcus mutans.

Passive immunization involving the delivery of antibodies specific to pathogens of infectious diseases to the host has been an attractive approach to establish protective immunity against a variety of microbial pathogens, including Streptococcus mutans, which is the principal etiologic agent of dental caries in humans. The overall purpose of the present study was to determine the effectiveness of a mouth rinse containing antibodies to S. mutans in preventing the establishment of this bacterium in dental plaque of humans. The antibodies were derived from egg yolks obtained from hens immunized with whole cells of S. mutans grown in sucrose-containing medium. The immunoglobulin derived from the yolks (IgY) of immunized hens was characterized in vitro and in vivo in human volunteers. Cross-reactivity tests showed that immune IgY reacted with every serotype, except serotype b, which had lost its GTase activity, when the bacteria were cultured in sucrose-containing medium. Immune IgY inhibited S. mutans adherence to saliva-coated hydroxyapatite discs by 59.2%, while control IgY caused an inhibition of only 8.2%. In the short-term (4-hour) test using a mouth rinse containing 10% sucrose, immune IgY decreased the ratio of the percentage of S. mutans per total streptococci in saliva. In the long-term (7-day) test using a mouth rinse without sucrose, the ratio in saliva was not significantly reduced in the volunteers using the immune IgY due to the large standard deviation. However, comparing the ratios of the percentage of S. mutans per total streptococci in plaque of individual subjects, there was a tendency for a reduction of the ratios in the volunteers receiving the mouth rinse containing immune IgY. These results support the effectiveness of IgY with specificity to S. mutans grown in the presence of sucrose as an efficient method to control the colonization of mutans streptococci in the oral cavity of humans.

Antibodies, Bacterial↗
PubMed1997

Extensive interbreeding occurred among multiple matriarchal ancestors during the domestication of dogs: evidence from inter- and intraspecies polymorphisms in the D-loop region of mitochondrial DNA between dogs and wolves.

To test the hypothesis that the domestic dogs are derived from several different ancestral gray wolf populations, we compared the sequence of the displacement (D)-loop region of the mitochondrial DNA (mtDNA) from 24 breeds of domestic dog (34 individual dogs) and 3 subspecies of gray wolf (Canis lupus lupus, C.l. pallipes and C.l. chanco; 19 individuals). The intraspecific sequence variations within domestic dogs (0.00-3.19%) and within wolves (0.00-2.88%) were comparable to the interspecific variations between domestic dogs and wolves (0.30-3.35%). A repetitive sequence with repeat units (TACACGTA/GCG) that causes the size variation in the D-loop region was also found in both dogs and wolves. However, no nucleotide substitutions or repetitive arrays were specific for domestic dogs or for wolves. These results showed that there is a close genetic relationship between dogs and wolves. Two major clades appeared in the phylogenetic trees constructed by neighbor-joining and by the maximum parsimony method; one clade containing Chinese wolf (C.l. chanco) showed extensive variations while the other showed only slight variation. This showed that there were two major genetic components both in domestic dogs and in wolves. However, neither clades nor haplotypes specific for any dog breed were observed, whereas subspecies-specific clades were found in Asiatic wolves. These results suggested that the extant breeds of domestic dogs have maintained a large degree of mtDNA polymorphisms introduced from their ancestral wolf populations, and that extensive interbreedings had occurred among multiple matriarchal origins.

Animals↗
PubMed1997

[A case of crush syndrome resulting from continuous compression of the upper arm by automatically cycled blood pressure cuff].

We report a case of crush syndrome (rhabdomyolysis) resulting from the prolonged compression of the inadvertently inflated blood pressure cuff around her upper arm. A 61-yr-old woman had undergone total gastrectomy, splenectomy and cholecystectomy for gastric cancer. At the end of the surgery lasting for 5 hrs 40 mins, we found the right upper arm extremely swollen with cyanotic petechiae beyond the inflated cuff. Failure of deflation of the automatically cycled blood pressure cuff was strongly suspected as a cause. She complained numbness and ardor on her hand with motor nerve disturbance and plasma CPK level was elevated. Diuretics were given and fluids were infused vigorously to prevent the renal failure, and continuous cervical epidural block was instituted to increase the blood flow to the injured arm. Prostaglandin E1 and ulinastatin (a protease inhibitor) were also effective for recovery from the crush syndrome. One month later she was discharged home accompanied with a slight numbness on the arm. Attention should be paid to deflation of the automatically cycled blood pressure cuff during anesthesia.

Alprostadil↗
PubMed1997

[Preliminary evaluation of the apparent diffusion coefficient of the kidney with a spiral IVIM sequence].

We examined the usefulness of the spiral intravoxel incoherent motion (IVIM) sequence in measuring the apparent diffusion coefficient (ADC) of the kidneys. Five volunteers and five patients with chronic renal failure underwent diffusion-sensitive magnetic resonance imaging of the kidneys with the spiral IVIM sequence. The ADC values in patients with chronic renal failure were significantly lower than those in the renal cortex of volunteers. The mean value of ADC in patients with chronic renal failure was lower than that in volunteers, although there was no statistically significant difference. In volunteers, the ADC of the renal cortex was significantly higher than that of the renal medulla. The phantom study indicated that the accuracy of ADC depended on the signal to noise ratio. A spiral IVIM sequence with a high enough signal to noise ratio may be useful in evaluating renal function especially that of the cortex.

Adult↗
PubMed1997

Hepatocellular carcinoma patients showing long-term complete responses to chemoembolization.

The objective was to evaluate hepatocellular carcinoma (HCC) patients showing a long-term complete response (CR) to chemoembolization. We defined the criteria of CR as normalized tumor marker, no enhanced tumor in diagnostic images, and no tumor cells found at autopsy. Five HCC patients showing long-term CR to chemoembolization were evaluated. The CR period ranged from 3.5 to 7 years (mean, 5.7 years). The survival period ranged from 3.5 to 9 years (mean, 6.7 years). Four cases (80%) were stage IV according to the TNM classification due to a portal tumor thrombus. The liver function was rated as Child's A in four cases (80%). Long-term CR to chemoembolization can be achieved even in some advanced HCC cases with a tumor thrombus. We speculate that the good antitumor effect is brought about by the stagnation of both the arterial and portal blood flows to the HCC. Good liver function is also considered to be an important factor for long-term CR and a long survival period. If the liver function is good, advanced HCC with a portal tumor thrombus should be treated aggressively with chemoembolization.

Aged↗
PubMed1997

[Trial of a detachable Y-shaped tube with two valves for serial examinations of CT arterial portography and CT hepatic arteriography].

In five patients with hepatocellular carcinoma, CT arterial portography (CTAP) and CT hepatic arteriography (CTHA) were performed serially by using a newly developed detachable Y-shaped tube with two valves that could be attached to a conventional angiographic sheath. Two catheters could be inserted into the conventional angiographic sheath without blood backflow by using the Y-shaped tube. One catheter could be easily and safety placed on the common or proper hepatic artery, and the other on the superior mesenteric artery. This detachable Y-shaped tube with two valves could make it easy to perform serial CTAP and CTHA examinations.

Angiography↗
PubMed1997

[Ruptured thymic cysts with mediastinal hemorrhage and hemothorax--a case report and reviews of the literature].

We report a rare case with rupture of thymic cyst including mediastinal hemorrhage and hemothorax. A 68-year-old man was referred to our hospital for the treatment of right hemothorax. A chest roentgenogram following thoracentesis demonstrated a widened mediastinum. Chest computed tomograms revealed a large anterior mediastinal mass extending to the right pleural cavity and bilateral pleural effusion. Digital subtraction angiography showed a normal aorta and great vessels. A median stenotomy revealed a large encysted hematoma along the thymic cyst extending from the right anterior mediastinum into the right pleural cavity and ending with rupture. Pathological examination demonstrated that the largest thymic cyst was continued to the hematoma resulting from partial destruction of its epithelial lining. To our knowledge, only five cases including our's with ruptured thymic tumors were reported, and this is the first report of ruptured thymic cyst resulting in mediastinal hemorrhage and hemothorax.

Aged↗
PubMed1996

Elevated erythrocyte sodium-lithium countertransport activity correlates with increased intracellular sodium and free calcium-ion concentration in type 2 diabetes.

To explore the mechanism by which elevated sodium-lithium countertransport activity (SLC) associates with both predisposition to hypertension and diabetic nephropathy, we investigated the interrelationships among SLC, intracellular sodium concentration ([Na]i), intracellular free calcium-ion concentration ([Ca2+]i), diabetic nephropathy, hypertension, family history of hypertension, and other factors in 48 patients with Type 2 diabetes and 24 healthy controls. There was a significant correlation between SLC and [Na]i (r = 0.36, p < 0.05), [Na]i and [Ca2+]i (r = 0.47, p < 0.01), SLC and [Ca2+]i (r = 0.46, p < 0.01), and between HbA1c and [Ca2+]i (r = 0.38, p < 0.01). Both [Na]i and [Ca2+]i were significantly higher in the patients with elevated SLC than in those with normal SLC (p < 0.01 and p < 0.05, respectively). In stepwise multivariate regresssion analysis, [Na]i, HbA1c, and SLC appeared as independent determinants of [Ca2+]i. These data suggest a significant correlation of elevated SLC with increased [Na]i and [Ca2+]i. This may be a possible mechanism underlying the close association of elevated SLC with both predisposition to hypertension and diabetic nephropathy.

Adult↗
PubMed1996

Ciliated foregut cyst in cirrhotic liver.

We encountered a patient with a ciliated hepatic foregut cyst with accompanying liver cirrhosis, which was hard to distinguish from well-differentiated hepatocellular carcinoma. A lesion 2 cm in diameter was found in the subcapsular region of the medial segment of the liver. It was slightly hypoechoic on ultrasonography, of high attenuation on nonenhanced computed tomography (CT), of high intensity on T1-weighted spin echo images of magnetic resonance imaging (MRI), and of isointensity on T2-weighted spin echo images. It was not enhanced in the arterial phase images of MRI, and was shown as a complete perfusion defect on CT arterial portography. The cyst was enucleated and found to be filled with bloody mucinous fluid.

Carcinoma, Hepatocellular↗
PubMed1996

Glutamatergic regulation of [3H]acetylcholine release in striatal slices of normotensive and spontaneously hypertensive rats.

It has been proposed that central cholinergic neurons may actively participate in blood pressure control and other cardiovascular regulations. The present study was performed to investigate the role of the glutamate receptors in the regulation of acetylcholine release in rat central nervous system in vitro. In the Mg2+-free condition, L-glutamate, an endogenous ligand for glutamate receptors, elicited [3H]acetylcholine release from striatal slices of Sprague-Dawley rats in a dose-related fashion. Glycine, an allosteric agonist for the N-methyl-D-aspartate type of glutamate receptor, significantly potentiated the increase in [3H]acetylcholine release evoked by L-glutamate. A non-competitive N-methyl-D-aspartate receptor antagonist, MK-801, blocked the L-glutamate-induced increase in [3H]acetylcholine release, although MK-801 had no effects on its own. In spontaneously hypertensive rats, the facilitatory effect of L-glutamate on [3H]acetylcholine release was significantly smaller than that in Wistar-Kyoto rats. Moreover, L-glutamate in combination with glycine increased the release of [3H]acetylcholine to a lesser extent in SHR than in WKY rats. These results show that L-glutamate increased acetylcholine release from rat striatum, which was highly dependent on the N-methyl-D-aspartate type of glutamate receptor. Furthermore, the lesser facilitation of acetylcholine release by L-glutamate in spontaneously hypertensive rats suggests that the excitatory amino acid may be, at least in part, involved in the regulation of central cholinergic nerve activity in hypertension.

Acetylcholine↗