Biomedical subjects

T Kihara

Publications and source records attributed to T Kihara.

At least 73 records · Page 4Linked to original sources

PubMed1998

[Frameless registration for chest SPECT and X-ray CT image by volume matching].

Image registration of functional (SPECT) and morphological (X-ray CT/MRI) images has been studied in order to improve the accuracy and the quality of the image diagnosis. This paper describes a new registration method for chest SPECT and X-ray CT images. Presented method is a frameless and automatic registration method which calculates a transformation matrix between two coordinate systems of image data by an optimization method. This registration method uses similar physical characteristics of X-ray CT and transmission CT image. The three-dimensional overlap of the body region is used for image matching. Precision evaluation and visual image evaluation were conducted. The result of the precision evaluation with a phantom and clinical data suggested the clinically acceptable robustness in registration procedure. Visual evaluation of registered images confirmed the usefulness of this method in clinical applications.

Algorithms↗

PubMed1997

BDNF prevents NO mediated glutamate cytotoxicity in cultured cortical neurons.

The effects of brain-derived neurotrophic factor (BDNF) on glutamate-induced cytotoxicity were examined using primary cultures of rat cortical neurons. BDNF induced TrkB tyrosine phosphorylation in rat cultured cortical neurons. The cell viability was significantly reduced when cultures were briefly exposed to glutamate and incubated with normal medium for 24 h. Glutamate cytotoxicity was prevented by MK-801, which is a non-competitive blocker of N-methyl-D-aspartate and N(omega)-nitro-L-arginine, which is a blocker of nitric oxide synthetase. Delayed neurotoxicity was also induced by ionomycin, a calcium ionophore, and nitric oxide (NO) donors such as S-nitrosocysteine (SNOC) and 3-morpholinosydnonimine (SIN-1). Incubating cultures with BDNF for 10 min to 24 h protected cortical neurons against glutamate neurotoxicity. The protective effects of BDNF against glutamate cytotoxicity were dependent on both its concentrations and incubation time. BDNF also prevented the ionomycin-, SNOC-, and SIN-1 induced cytotoxicity. These results indicate that BDNF protects cultured cortical neurons from NMDA receptor-mediated glutamate neurotoxicity by reducing cytotoxic action of NO.

Animals↗

PubMed1997

Identification and activation of profollipsin, a latent precursor form of porcine follipsin.

A latent protease has been identified in column fractions obtained during the purification of the porcine ovarian serine protease follipsin. The latent enzyme was readily activated by trypsin treatment. The trypsin-activated enzyme was purified using a benzamidine-Sepharose 6B column and was shown to be composed of two distinct, covalently associated polypeptides with Mr of 45000 and 32000. This polypeptide chain composition, together with its substrate specificity, inhibition profile using various protease inhibitors, cross-reactivity with anti-follipsin antibody, and ability to activate single-chain precursor tissue plasminogen activator, indicated its identity as porcine follipsin. The activation of the enzyme with trypsin was found to occur by the hydrolysis of an internal peptide bond resulting in a two-chain structure. Thus, we conclude that the latent enzyme is the inactive precursor form (profollipsin) of follipsin. The present study also shows that the follicular fluid of porcine ovary contains a profollipsin-activating enzyme activity.

Animals↗

PubMed1997

Nicotinic receptor stimulation protects neurons against beta-amyloid toxicity.

beta-Amyloid (A beta), a major constituent of senile plaques in Alzheimer's disease (AD), is thought to contribute to the neurodegeneration. We examined the effects of nicotinic receptor agonists on A beta cytotoxicity in cultured rat cortical neurons. The number of viable neurons decreased significantly when cultures were exposed to synthetic A beta peptides (25-35). Concomitant administration of nicotine with A beta markedly reduced the number of dead cells. This nicotine-induced neuroprotection was dependent on the concentration. When hexamethonium or mecamylamine, nicotinic antagonist, was added, neuroprotective effect of nicotine was blocked, which indicates that effect of nicotine was mediated by nicotinic receptors. In addition, a selective alpha7-receptor antagonist, alpha-bungarotoxin (alpha-BTX), blocked the neuroprotective effect of nicotine. Furthermore, incubation with 3-(2,4)-dimethoxybenzylidene anabaseine (DMXB), a selective alpha7-receptor agonist, protected against A beta-induced neuronal death. These results suggest that alpha7-receptor activation plays an important role in neuroprotection against A beta cytotoxicity. This study suggests that nicotinic receptor stimulation, especially alpha7-receptor activation, may be able to protect neurons from degeneration induced by A beta and may have effects that counter the progress of AD.

Amyloid beta-Peptides↗

PubMed1997

A prospective randomized study of glutamine-enriched parenteral compared with enteral feeding in postoperative patients.

Plasma amino acids were measured in 17 postoperative subjects randomly assigned to receive for > or = 5 d tube feeding or total parenteral nutrition (TPN) that had identical energy, nitrogen, and glutamine contents. Subjects required gastric or pancreatic surgery for malignancy and were well-matched for age and body mass index. Tube feeding or TPN began on postoperative day 1 and advanced in daily 25% increments to meet goals of 105 kJ . kg body wt-1 . d-1, 1.5 g protein . kg body wt-1 . d-1, and 0.3 g glutamine . kg body wt-1 . d-1. Delivered energy, nitrogen, and glutamine were closely matched on day 4. Nitrogen balance and plasma proteins did not differ significantly between feeding groups. Total indispensable amino acids, branched-chain amino acids, and glutamine declined 25% on postoperative day 1 compared with preoperative day 0. Indispensable and branched-chain amino acid concentrations were restored with 5 d of either tube feeding or TPN. Glutamine concentrations did not differ significantly by feeding group, though a trend suggested that glutamine recovered more slowly in the tube-fed than in the TPN-fed subjects. Plasma amino acids otherwise reflected formula composition with ratios of valine to leucine of 1.24 and 3.69 mumol/L in subjects receiving 5 d of tube feeding or TPN, respectively. These findings suggest that glutamine-enriched tube feeding and TPN can result in similar profiles for most plasma amino acids at carefully matched doses.

Adolescent↗

PubMed1997

Endoscopic diagnosis of hookworm disease of the duodenum.

Hookworm is one of the most common parasites in the world, but can be missed on stool examination. We report a 31-year-old man who was complaining of epigastric discomfort, with laboratory findings of iron-deficiency anemia and eosinophilia. He was found to be infected with hookworm (Ancylostoma duodenale), which was directly detected and retrieved from the duodenum with biopsy forceps during upper gastrointestinal endoscopy. We eliminated his infection successfully by the Damaso de Rivas-Kihara modified method and oral administration of pyrantel pamoate. This report indicates that it is important to check carefully even in the distal duodenum at routine upper gastrointestinal endoscopy whenever parasitic disease is suspected but is hard to diagnose because of a limited number of eggs in feces.

Adult↗

PubMed1997

[Utility of prostate specific antigen (PSA) density in detecting prostate cancer in men showing gray zone serum PSA levels].

The efficacy of prostate specific antigen density (PSAD) in diagnosing prostate cancer was assessed in 98 patients with serum prostate specific antigen (PSA) levels between 2 and 10 ng/ml who had a pathological diagnosis made by prostate biopsy or transurethral resection of the prostate. Of the 98 patients, 22 (22%) had prostate cancer. The PSA (based on a cut-off value of 4.5 ng/ml) had a sensitivity and positive predictive value (PPV) of 82% and 38%, respectively, for diagnosing prostate cancer, while the results for PSAD (based on a cut-off value of 0.13) were 91% and 61%. The PSAD was more efficient than the PSA levels and was also superior to digital rectal examination (DRE) combined with transrectal ultrasonography (TRUS), for which the sensitivity and PPV were 73% and 39%, respectively. Six (11%) out of 57 patients who were normal on DRE and TRUS had prostate cancer. In these 57 patients, the PSA (cut-off value: 4.5 ng/ml) had a sensitivity of 50% and PPV while the values for PSAD (cut-off value: 0.13) were 83% and 36% respectively. The PSAD could effectively detect even impalpable prostate cancer not visible on TRUS.

Aged↗

PubMed1997

[Bladder carcinoma presenting with hypercalcemia: a case report].

A 47-year old woman was referred to our hospital with nausea, vomiting and the loss of body weight. Pelvic computed tomography and magnetic resonance imaging revealed an invasive bladder tumor on the left lateral wall, accompanied with calcification. Laboratory examination revealed marked hypercalcemia (20.6 mg/dl) and elevated serum parathyroid hormone-related protein-intact (29.9 pmol/l), which was apparently produced by the tumor. Treatment with pamidronate and colloid infusion resulted in normocalcemia. Anterior pelvic exenteration was performed. Histopathological diagnosis was transitional cell carcinoma > adenocarcinoma, G3, pT4pN2M0, stage IV. She died of cancer 7 months postoperatively.

Carcinoma, Transitional Cell↗

PubMed1997

[Pheochromocytoma of the left retroperitoneal paraganglion associated with torsade de pointes: a case report].

A 54-year-old woman developed torsade de pointes with secondary QT prolongation due to hypokalemia and hypomagnesemia. Her serum K and Mg levels were 2.5 mEq/l and 1.5 mg/dl, respectively. This electrolyte imbalance was due to intentional overdosing of metolazone. Attacks of torsade de pointes occurred three times in the intensive care unit and were corrected by intravenous lidocaine administration. Her serum K level was corrected using KCl infusion, restoring the normal QT interval. Routine computed tomography found a left retroperitoneal paraganglioma. Urinary and serum catecholamine examination revealed extremely high values of epinephrine and norepinephrine. The diagnosis was pheochromocytoma in the left retroperitoneal paraganglion. The tumor which was removed measured 70 x 65 x 60 mm in size. Microscopic examination revealed the characteristic patterns of pheochromocytoma.

Diuretics↗

PubMed1997

[A case of xanthogranuloma of the urinary bladder].

A case of xanthogranuloma of the urinary bladder is reported. A 68-year-old man was referred to our hospital for the evaluation of microscopic hematuria. At that time, he did not have an abdominal tumor and ultrasonography showed no abnormality of the kidneys and the bladder wall. Two months later, he was admitted with the chief complaints of perineal discomfort and non tender fist size mass was palpable in the lower abdomen. Ultrasonography, computed tomographic scan and magnetic resonance imaging MRI demonstrated a supravesical mass which was strongly suspected as urachal tumor. Total cystectomy with urachal resection was performed. The histological diagnosis was xanthogranuloma. The patient has been in good health without recurrence, 4 years after surgery. We discuss xanthogranuloma of the urinary bladder in the literature.

Aged↗

PubMed1996

Change in ascorbate radical production in an irradiated experimental tumor with increased tumor size.

We have reported that ascorbate radical (Asc.-) could serve as an indicator of the amount of hydroxyl radical and superoxide produced by irradiation in vivo. Using this method, we investigated the relationship between tumor size and Asc.- production after irradiation (10 Gy) and between tumor size and the radical-scavenging ability of WR-2721 (300 mg/kg). Asc.- was measured in normal muscle and SCC-VII tumors transplanted into mice (n = 6). In tumors, the increase in Asc.- significantly decreased with increasing tumor size (r = -0.483; P < 0.05). The increase in Asc.- production after irradiation was more inhibited by WR-2721 in normal muscle tissue than in tumor tissue at various sizes. In tumors, the increase in Asc.- was less inhibited by WR-2721 with increasing tumor size. These results demonstrate that the increase in radical production after irradiation and drug distribution decreased with increasing tumor size and that WR-2721 has excellent differential protection. This method is expected to measure changes in the amounts of local hydroxyl radical and superoxide modified by a change of tumor environment or drug administration.

Amifostine↗

PubMed1996

NF-kappa B is induced in the nuclei of cultured rat aortic smooth muscle cells by stimulation of various growth factors.

We investigated whether induction of transcription factor NF-kappa B is involved in the proliferation of cultured rat aortic smooth muscle cell using electrophoretic mobility shift assay and immunocytochemistry. NF-kappa B was induced in the nucleus in a dose-dependent manner when the smooth muscle cells were stimulated by various growth factors such as PDGF-BB, bFGF, EGF and IGF-1, but not growth inhibitors such as TGF-beta and IFN-gamma. Among growth factors, PDGF-BB and bFGF, more potent growth stimulators, induced higher kappa B binding activity than EGF or IGF-1. These evidences were also supported by the results obtained with immunocytochemistry. Immunocytochemistry also showed that the induced NF-kappa B contained p50 and p65. These results suggest that NF-kappa B induction may be involved in the proliferation of vascular smooth muscle cell.

Animals↗

PubMed1996

Role of platelet-activating factor and thromboxane A2 in radical production during ischemia and reperfusion of the rat brain.

Oxygen radicals produced by activated neutrophils have been involved in brain injury during ischemia-reperfusion. Platelet-activating factor (PAF) is a candidate as one of the mediators of neutrophil activation during cerebral ischemia-reperfusion. Recent evidence indicates that PAF-induced neutrophil activation is mediated by thromboxane A2 (TXA2). To study the role of PAF and TXA2 in radical production during cerebral ischemia-reperfusion, we evaluated the effects of a PAF antagonist, Y-24180, and a TXA2 antagonist, S-1452, on radical formation in rats with 1 h middle cerebral artery (MCA) occlusion. In the present study, we employed a new electron spin resonance (ESR) method coupled with brain microdialysis. The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents. In the vehicle controls, extracellular AR from the ischemic brain cortex decreased during MCA occlusion. Following reperfusion, AR significantly increased at 30 mm and 1 h, returned to near the basal levels at 2 h, and increased again at 24 h after reperfusion. In the rats treated with S-1452 or Y-24180, AR decreased during MCA occlusion to the same extent as in the vehicle control. However, pretreatment with Y-24180 or S-1452 significantly attenuated the increase in extracellular AR after reperfusion, while it exerted no effect on the changes in extracellular ascorbate or tissue pO2 throughout the experimental period. In conclusion, PAF and TXA2 might contribute to cerebral ischemia-reperfusion injury by increasing the generation of oxygen radicals.

Animals↗

PubMed1996

Possible release of nitric oxide from cholinergic axons in the thalamus by stimulation of the rat laterodorsal tegmental nucleus as measured with voltammetry.

By means of the differential direct current voltammetry technique with carbon fiber electrodes in urethane-anesthetized rats, we monitored nitric oxide (NO) concentrations in the thalamus in the basal condition and following electrical stimulation of the laterodorsal tegmental nucleus (LDT), whose neurons have the strongest activity of NADPH-diaphorase, or NO synthase, together with acetylcholine. NO levels, measured as the height of the peak at +970-1000 mV in the voltammetry (NO was soon oxidized in vivo to be detected at the voltage of this peak, so that NO levels in this report are, in the strict sense, levels of the oxidized metabolites reflecting very possibly those of NO in physiological conditions; see Section 2, Methods), increased just after repetitive stimulation of the LDT. Stimulation of the surrounding areas or the cerebellum produced virtually no change in NO levels. An intravenous injection of L-nitroarginine methyl ester reduced the basal level of NO, but stimulation of the LDT still increased NO levels, which may be due to very strong activity of NO synthase in the LDT neurons. These results are consistent with the notion that NO can be released from axons of the LDT neurons by their excitation.

Animals↗

PubMed1996

Studies on transient graft-versus-host disease in BALB/c nude mice injected with allogeneic C57BL/6 splenocytes.

Graft-versus-host disease (GVHD) is known to cause profound dysregulation of the immune system, although its effector mechanisms are not fully understood. In this study, we investigated what factors influenced the development of GVHD. BALB/c nude mice (H-2d) injected with MHC-disparate B6(H-2b) spleen cells exhibited transient GVHD such as hunched back, diarrhea, loss of body weight and splenomegaly. No animals died during the period of observation. BALB/c nude mice produced alloantibodies to the donor cells. The injection of the serum from GVHD nude mice into naive nude mice can protect from GVHD. Donor derived H-2b+ cells were recognized in the recipient lymph nodes and skin. Prevention of GVHD was achieved by the pretreatment of spleen cells with anti-Thy-1.2 antibody or anti-CD4 antibody and complement, while it was not done by the pretreatment of spleen cells with anti-CD8 antibody and complement. These data demonstrate that Thy-1.2+ CD4+ CD8- lymphocytes are important effector cells and alloantibodies to the donor cells prevent GVHD in this model.

Animals↗

PubMed1996

A novel benzodiazepine inverse agonist, S-8510, as a cognitive enhancer.

1. Pharmacological actions of a novel benzodiazepine receptor ligand, S-8510 (2-(3-isoxazolyl)-3,6,7,9-tetrahydroimidazo[4,5-d]pyrano+ ++[4,3-b] pyridine monophosphate monohydrate), were examined in in vitro and in vivo studies. 2. S-8510 was characterized as a partial inverse agonist with a modest GABA ratio and low efficacy. 3. S-8510 ameliorated memory impairment induced by cholinergic deficit in the water maze paradigm of Wistar rats. 4. S-8510 augmented LTP of the Schaffer collateral/commissural fiber-CA1 synapses in the hippocampal slice preparations of SD rat. 5. S-8510 increased the extracellular levels of acetylcholine and noradrenaline in the hippocampus of Wistar rat. 6. S-8510 selectively potentiated pentylenetetrazol-induced convulsion without affecting minimal electroconvulsive shock- or strychnine-induced convulsion in ddY mice. 7. S-8510 failed to induce any sign of anxiety in the Wistar rat pro-conflict test. 8. S-8510 showed antidepressant-like pharmacological actions in ddY mice. 9. These results suggest that S-8510 can be used as a therapeutic drug for senile dementia, including Alzheimer's disease with little risk for inducing anxiety or convulsion.

Animals↗

PubMed1996

A revised cold water immersion test for assessing peripheral circulatory function.

To improve the conventional cold water immersion test for assessing peripheral circulatory function, the immersed area of the hand was changed in this study. Twenty-seven healthy medical students with a mean age of 24 years participated in the study. The cold water immersion tests were carried out using two methods (in 5 degree C water for 1 min), in which the immersed area was up to the metacarpophalangeal (MP) joints (hereafter, MP-method) which is a new method, or to the wrist (hereafter, W-method) which is a conventional method. The recovery of skin temperature, vibratory perception threshold and complaints of finger pain were determined during cold immersion tests with the two methods. The mean skin temperature for the MP-method after immersion recovered more quickly than that for the W-method. However, the time courses of recovering were parallel for the two methods. Significant differences were noted at 3 min, 5 min and 10 min after cessation of immersion. There was a significant positive correlation in the recovery rates at 5 min after immersion between the two methods (correlation coefficient = 0.65, p < 0.01). The mean vibratory thresholds for the W-method were higher than those for the MP-method, and the difference was significant (p < 0.01). All subjects preferred the MP-method to the W-method because there was less finger pain. These results indicate that the MP-method, immersion up to the MP joint of a hand, for assessing peripheral circulatory function is better than the W-method.

Adult↗

PubMed1996

Liver haem metabolism in adjuvant-induced arthritic rats.

1. Adjuvant-induced arthritic (AA) rats show a striking decrease in the level of cytochrome P450, a key microsomal haemoprotein involved in electron transport and drug metabolism in the liver. In the present study, we examined the relationship between the reduction of P450 content and haem metabolism in the liver of AA rats. 2. The activities of many enzymes catalyzing the biosynthesis of haem in the liver were significantly higher in AA rats than in normal rats, whereas only coproporphyrinogen oxidase activity in AA rats was markedly lower than that in normal rats. Furthermore, the activity of haem oxygenase, a key enzyme in the haem degradative pathway, increased significantly in AA rats. In addition, the degree of increase in the activity of this enzyme was clearly higher than that in the activity of 5-aminolevulinate synthase, a key enzyme in the haem synthetic pathway. 3. These results suggest that the reduction of live P450 content in AA rats is based on the lowering of liver haem content due to the combined action of the increased haem oxygenase activity and the decreased coproporphyrinogen oxidase activity. The changes in these enzyme activities were apparently suppressed by the continuous administration of indomethacin, which improved the arthritic states of the animals.

5-Aminolevulinate Synthetase↗