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Biomedical subjects

M Kageyama

Publications and source records attributed to M Kageyama.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effects of the immunosuppressant cyclosporin A on neurotransmitter release from peripheral non-adrenergic, non-cholinergic nerves.

This study was undertaken to determine the effect of the immunosuppressant cyclosporin A on neurotransmitter release from non-adrenergic, non-cholinergic nerves (tachykininergic nerves) in the rabbit iris sphincter muscle. Cumulative application of cyclosporin A (0.1 to 10 microM) caused a slow onset of contraction in a concentration-dependent manner. Both FK888 (1 microM) and capsaicin (10 microM), a substance P receptor antagonist and a substance P-depleting agent, respectively, inhibited the contractile effect of cyclosporin A, whereas atropine (1 microM) had no effect. Both cyclosporin A and capsaicin (10 microM) stimulated the release of substance P-like immunoreactivity in the iris. Neither the sodium channel blocker tetrodotoxin (1 microM), the N-type voltage-dependent Ca2+ channel blocker omega-conotoxin GVIA (1 microM) nor the P-type channel blocker omega-agatoxin IVA (0.2 microM) affected cyclosporin A (1 microM)-induced contraction. In contrast, the L-type Ca2+ channel blocker nicardipine (10 microM) inhibited this contractile effect. These results suggest that cyclosporin A stimulates substance P-like tachykinin release by activating L-type voltage-dependent Ca2+ channels, resulting in contraction of the rabbit iris sphincter muscle.

Animals↗
PubMed1997

Sequential subtraction scintigraphy with 99Tcm-RBC for the early detection of gastrointestinal bleeding and the calculation of bleeding rates: phantom and animal studies.

To improve the detectability of gastrointestinal (GI) bleeding, we have developed a new method, 'sequential subtraction scintigraphy' (SSS) with 99Tcm-labelled red blood cells (RBC). Sequential subtraction scintigrams were obtained by subtracting 5 min interval images from each other using a digital gamma camera. With this method, we are able to detect the bleeding site and calculate the bleeding rate earlier because of the lower background activity. The results of the present study demonstrate that the minimum detectable bleeding rate was 0.05 ml min-1 in both a phantom and an animal model. The minimum detectable activity volumes within 10 min were 0.5 ml by SSS and more that 3 ml by conventional non-subtraction scintigraphy (CNS). The bleeding rates calculated with the subtraction method correlated well with the actual syringe pump rates. The detectability of GI bleeding by SSS and CNS in animal models was compared using the area under receiver operator characteristic (ROC) curves. The results showed that SSS significantly increased the area under the ROC curves from 0.55 +/- 0.05 to 0.79 +/- 0.04 for the 10 min image set and from 0.65 +/- 0.05 to 0.83 +/- 0.04 for the 30 min image set (Z = 5.45, P < 0.0001 and Z = 4.36, P < 0.0001, respectively). These results suggest that sequential subtraction scintigraphy with 99Tcm-RBC is an effective method for the early detection of GI bleeding when compared with the conventional non-subtraction method.

Adult↗
PubMed1997

[A case of congenital retinoschisis with unexpected appearance and spontaneous regression].

A case of congenital retinoschisis, with both unexpected appearance and spontaneous regression, is reported. The patient, a 22-year-old man, had been diagnosed with congenital retinoschisis when he was 11 years old. The ocular fundus showed bilateral foveal retinoschisis and peripheral retinoschisis in the right eye. Early in November 1991, he visited our hospital and complained of a visual field defect in the left eye. The ocular fundus of the left eye showed high ballooning retinoschisis. However, two weeks later, the ballooning retinoschisis had completely disappeared. Appearance and regression of peripheral retinoschisis of congenital retinoschis in an adult is a very rare occurrence.

Adult↗
PubMed1996

Extensive soft-tissue involvement of dermatomyositis detected by whole-body scintigraphy with 99mTc-MDP and 201TL-chloride.

The authors present a case of extensive soft-tissue radioactivity visualized on both 99mTc-MDP and 201Tl-chloride scintigrams in a patient with dermatomyositis and colon cancer. Incidentally, diffuse and intense uptake of 99mTc-MDP was observed in the shoulder girdles, anterior chest wall, psoas muscles, both proximal thighs and right lower limb, corresponding to the sites of symptomatic muscles, even though skin lesions were limited and no calcification was detected on radiographs. Moreover, 201Tl-chloride was also intensely accumulated in nearly the same sites as the symptomatic muscles as shown on the 99mTc-MDP bone scintigrams. Whole-body scintigraphy with 99mTc-MDP and 201Tl-chloride is a useful tool to detect occult muscle lesions with dystrophic calcification and hyperemia in dermatomyositis.

Calcinosis↗
PubMed1996

Endothelin-1 mediated Ca2+ influx does not occur through L-type voltage-dependent Ca2+ channels in cultured bovine trabecular meshwork cells.

We evaluated whether endothelin-1-induced changes in cytosolic Ca2+ concentration ([Ca2+]i) involve Ca2+ influx through L-type membrane voltage-dependent Ca2+ channels in cultured bovine trabecular meshwork (TM) cells. The cells were loaded with the fluorescent Ca2+ indicator fura-2 and cell-associated fluorescence was measured with a digital video-imaging analyzer. Application of carbachol (10(-3) M) and norepinephrine (10(-5) M) increased [Ca2+]i only transiently. Endothelin-1 (10(-9) M to 10(-7) M) also increased [Ca2+]i in a concentration-dependent manner, and its effects were larger than those of carbachol and norepinephrine. Unlike carbachol or norepinephrine, endothelin-1 evoked a peak transient effect followed by a sustained elevated level of [Ca2+]i. The only level of the sustained elevated component was dependent on extracellular Ca2+. However, pretreatment with diltiazem (10(-5) M and 10(-4) M), an L-type Ca2+ channel blocker, did not affect either component of the endothelin-1-induced increase in [Ca2+]i. These results suggest that in cultured bovine TM cells endothelin-1 receptors are coupled to Ca2+ signaling mechanisms. However, the extracellular Ca(2+)-dependent increase in [Ca2+]i may not involve Ca2+ influx through L-type Ca2+ channels.

Adrenergic alpha-Agonists↗
PubMed1996

Brain SPECT of Creutzfeldt-Jakob disease.

SPECT imaging with I-123 IMP or Tc-99m HMPAO was performed in two patients with Creutzfeldt-Jakob disease to evaluate abnormalities in brain perfusion. In the first patient, there was decreased perfusion of the left frontal, parietal, and temporal lobes. CT and MRI were negative. In the second patient, there was patchy perfusion and slightly decreased perfusion of the right hemisphere. MRI revealed slight brain atrophy and bilateral high intensity areas in the basal ganglia on T2 weighted images. Subsequent SPECT imaging revealed severely decreased perfusion of the entire brain. Subsequent MRI demonstrated severe brain atrophy.

Aged↗
PubMed1996

Simultaneous assessment of regional adrenergic activity and perfusion with 123I-MIBG and 201Tl in congestive heart failure.

Simultaneous assessment of regional adrenergic activity and perfusion with 123I-meta-iodobenzylguanidine (123I-MIBG) and 201Tl in various organs was performed in 13 patients with congestive heart failure (CHF) and 13 subjects without heart failure. In order to reduce the crosstalk of 201Tl to the 123I energy window to less than 5%, a dose of 123I-MIBG more than five times greater than that of 201Tl was administered following 201Tl scintigraphy. Regional uptake of 201Tl (%dose) was significantly increased in the heart (left ventricle) and lung (both P < 0.01) in the patients with CHF. The increased global cardiac uptake could have been related to the enlarged left ventricle. The patterns of regional uptake of 123I-MIBG (% dose) at 15 min were similar to those of 201Tl, suggesting that early 123I-MIBG uptake could in part depend on regional perfusion in both groups. At 3 h, regional uptake of 123I-MIBG was significantly increased in the heart, lung and kidney (all P < 0.01) in the patients with CHF. The delayed 123I-MIBG uptake indicates the degree of neuronal accumulation of the tracer, and therefore reflects adrenergic activity. Interestingly, the cardiac 123I-MIBG (adrenergic activity) to 201Tl (unit of perfusion) ratio decreased significantly in the heart (P < 0.01) but increased significantly in the kidney (P < 0.01) in the patients with CHF compared with the control group. Cardiac 123I-MIBG washout was also significantly increased in the CHF patients. Moreover, the cardiac 123I-MIBG:201Tl ratio was negatively correlated with plasma norepinephrine concentration (r = -0.74, P < 0.01), but positively correlated with LVEF (r = 0.60, P < 0.01). These data suggest that there may be impairment of both the neuronal uptake function and the vesicular storage function in the failing heart, and an increment in neuronal uptake function in the kidneys in patients with CHF. We suggest that dual-tracer scintigraphy is a useful non-invasive method for the simultaneous assessment of adrenergic activity and perfusion in various organs in patients with heart failure.

3-Iodobenzylguanidine↗
PubMed1996

Construction and characterization of pyocin-colicin chimeric proteins.

Chimeric proteins were constructed from pyocin S1 or S2 and colicin E3 or E2, and their characteristics were investigated with special reference to the domain structure. The nuclease domains were interchangeable between two bacteriocins so that a new kind of pyocin, with RNase activity, was created. A bacteriocin which can kill both Pseudomonas aeruginosa and Escherichia coli was also constructed. Investigations with various chimeric proteins indicate that the translocation domain as well as the receptor-binding domain is species specific. Inhibition of lipid synthesis, which is characteristic of pyocins, was also observed with chimeric pyocins carrying the DNase domain of colicin E2 but not with those carrying the RNase domain of E3. Thus, the DNase domain is responsible for the inhibition of lipid synthesis.

Bacterial Proteins↗
PubMed1996

[Application of oculokinetic perimetry in examination of the eye].

Oculokinetic perimetry was performed using the same protocol at four health screening facilities to determine its usefulness for identifying visual field abnormalities including glaucoma during complete physical screenings in Japan. Ophthalmoscopy of the optic disc, 26-point oculokinetic perimetry (OKP), and applanation tonometry were performed in 2,768 eyes. If any one of the tests yielded an abnormal result, the eye was then examined with a Humphrey visual field analyzer (HVFA, program 30-2). After the tests were completed, the results were evaluated by ophthalmologists for evidence of primary open-angle glaucoma and normal tension glaucoma and were classified into one of 3 groups: confirmed glaucoma, suspected glaucoma, and no glaucoma. OKP detected abnormalities in the visual field in 96 eyes (3.5%). Of these 96 eyes, 29 eyes had confirmed glaucoma, 52 eyes were suspected of having glaucoma and 15 eyes had no glaucoma. The remaining 15 eyes had no glaucoma, but in 7 of them other ophthalmological disease was diagnosed. The sensitivity, specificity, positive predictive value, and negative predictive value of OKP for detecting glaucomatous visual field defect were 0.46, 0.99, 0.84 and 0.96, respectively. The high specificity and negative predictive value show that OKP is unlikely to produce false positive results, but its low sensitivity suggests that it is not suitable for the early detection of glaucoma. However, OKP identified advanced glaucoma and other ophthalmological diseases associated with visual field abnormalities, suggesting that it is a useful screening test.

Adult↗
PubMed1995

Selective prostaglandin D2 receptor stimulation elicits ocular hypotensive effects in rabbits and cats.

The effects of the selective prostaglandin D2 (DP) receptor agonists, 572C85 ((+/-)-5-(3-carboxypropylthio)-1-(2-cyclohexyl-2-hydroxyethyl- amino)hexahydrocyclopenta(d)imidazol-2(1H)-one) and 192C86 ((+/-)-5-(3-carboxypropylthio)-1-(2-cyclohexyl-2-hydroxyethylidene - amino)-3-ethylhexahydrocyclopenta(d)imidazol-2(1H)-one), were determined on intraocular pressure regulation in rabbits and cats. 572C85 (50 micrograms) in rabbits maximally lowered intraocular pressure by 4.3 mm Hg, and significantly for 4 h compared to control. In cats 572C85 had a similar effect. 192C86 (50 micrograms) reduced intraocular pressure by 2.8 mm Hg for 2 h in rabbits. Following exposure to the specific DP receptor antagonist, BW A868C ((+/-)-3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexyl-2-hydroxyethylamin o)- hydantoin; 50 micrograms), which had no effect on intraocular pressure by itself, 572C85 (50 micrograms) did not reduce intraocular pressure in rabbits and cats. The intraocular pressure lowering effect of the mixed DP and EP receptor agonist, BW245C (5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl)-hydantoin; 50 micrograms), in cats was suppressed by only 64% by BW A868C (50 micrograms). These results clearly show that the DP receptors in rabbit and cat eyes are involved in intraocular pressure regulation. However, under baseline conditions DP receptor activity does not contribute to this regulation.

Animals↗
PubMed1995

Concurrent detection of cholecystocolic fistula and hepatic abscess by hepatobiliary scintigraphy.

We report the case of a 58-year-old male with cholecystocolic fistula and hepatic abscess that were not diagnosed by routine radiologic examinations, but concurrently detected by hepatobiliary scintigraphy with 99mTc-PMT, and confirmed at operation. Hepatobiliary scintigraphy is noninvasive and useful in the detection of a biliary enteric fistula and lesions about related organs. Concurrent detection of cholecystocolic fistula and hepatic abscess on hepatobiliary series is of great clinical value in planning surgical intervention.

Biliary Fistula↗
PubMed1995

Postgastrectomy osteomalacia with pseudofractures assessed by repeated bone scintigraphy.

A patient with osteomalacia secondary to vitamin D deficiency after gastrectomy for gastric cancer is presented. Initial bone scintigrams showed both asymmetric and symmetric focal areas of intense uptake due to pseudofractures reminiscent of bone metastases. Radiographs only confirmed the presence of pseudofractures at some, but not all, of the abnormal sites demonstrated by bone scintigraphy. At first, metastatic bone disease was suspected. However, the appearance of repeated bone scintigram was normalized after treatment with vitamin D. A diagnosis of osteomalacia was established. The present case serves to illustrate that symmetric focal lesions are important features of pseudofractures secondary to osteomalacia, and comparison with radiographs and repeated bone scintigraphy are necessary in distinguishing between bone metastases and pseudofractures.

Bone Neoplasms↗
PubMed1995

The value of combined 99mTc-Sn-colloid and 99mTc-RBC scintigraphy in the evaluation of a wandering spleen.

Wandering spleen is the term commonly applied to splenic hypermobility that results from laxity or maldevelopment of its suspensory ligaments. It comes to medical attention usually as an abdominal mass, or when the spleen undergoes torsion. Diagnosis on clinical grounds alone is rarely made, and ultrasonography, CT and MRI findings have no specific characteristics for this condition. 99mTc-labeled colloid taken up by the spleen may provide a specific diagnosis. We report a case of wandering spleen, in which the preoperative diagnosis was made on the basis of sequential liver-spleen scintigraphy with 99mTc-Sn-colloid and blood-pool scintigraphy with 99mTc-RBC. This is a rare case, in which hypermobility was assessed by sequential 99mTc-Sn-colloid scintigraphy, and to our knowledge, is the first case in which 99mTc-RBC scintigraphy provided useful information on splenic blood volume and its location.

Adult↗
PubMed1995

Sequential subtraction scintigraphy with 99mTc-RBC for the early detection of gastrointestinal bleeding.

To improve the early detectability of gastrointestinal (GI) bleeding, we have developed a new subtraction scintigraphic technique using in vivo labeled 99mTc red blood cells (RBC). Use of this new sequential subtraction method every 5 min makes it possible to detect early the bleeding site and calculate the bleeding rate. In phantom experiments, focal activity was detected on subtraction images at pump rates of more than 0.20 ml/min at any urethane thickness, but was negative on conventional scintigrams. The calculated pump rate by the subtraction method correlated well with the actual syringe pump rate (y = 1.07x - 0.02, r = 0.99, p < 0.01) in the case of an 8-cm urethane board as an abdominal wall. Twenty-four of 50 patients with suspected GI bleeding were confirmed to be positive within 24 hr. The subtraction method showed 15 true positive and 2 false positive cases within 60 min. On the other hand, the conventional scintigraphic method showed only 7 true positive and 1 false positive cases. Sensitivity of the subtraction method was 62.5%, which was significantly higher (p < 0.05) than that of the conventional scintigraphic method (29.2%). These results suggest that sequential subtraction scintigraphy with 99mTc-RBC is an effective method for the early detection of GI bleeding and shortening the examination time as compared with conventional scintigraphy.

Adolescent↗
PubMed1995

L-type voltage-dependent Ca2+ and ATP-sensitive K+ channels are not involved in the regulation of bovine ciliary muscle contractility.

We compared the effects of L-type voltage-dependent Ca2+ and ATP-sensitive K+ channels modulators on contractility in isolated bovine ciliary muscle with those in rabbit aortae. Nifedipine (0.1 and 1 microM), a dihydropyridine Ca2+ channel blocker, did not relax bovine ciliary muscle precontracted with 100 mM KCl. Nondihydropyridine Ca2+ channel blockers, semotiadil fumarate (SD-3211, 1 microM) diltiazem (10 microM) and verapamil (1 microM), did not affect contractility, but at higher concentrations, they all had a relaxant effect. Bay K 8644, a L-type voltage-dependent Ca2+ channel activator, even at 1 microM, did not contract ciliary muscle partially depolarized with 10 mM KCl, whereas at 0.01 and 0.1 microM it contracted partially depolarized rabbit aortae. Furthermore, diazoxide (100 microM), an ATP-sensitive K+ channel opener, had a relaxant effect on aortae precontracted with 25 mM KCl, but not on ciliary muscle. This relaxation was inhibited by glibenclamide (10 microM), an ATP-sensitive K+ channel blocker, indicating that diazoxide relaxes rabbit aortae by activating ATP-sensitive K+ channels. These results suggest that L-type voltage-dependent Ca2+ and ATP-sensitive K+ channels play a minor role in the regulation of bovine ciliary muscle contractility.

Adenosine Triphosphate↗
PubMed1995

Brain SPECT with neuro-Behçet disease.

A patient with neuro-Behcet disease is described. SPECT using Tc-99m HMPAO was performed to evaluate brain perfusion. The brain SPECT revealed decreased perfusion in the right frontal, parietal, temporal, and occipital lobes. MRI showed high intensity lesions in the white matter in the right periventricular centrum semiovale and frontal region on T2 weighted images. Gray matter abnormalities were evident on brain SPECT, but not on MRI. Brain SPECT using Tc-99m HMPAO may provide useful clinical information on regional cerebral cortical abnormalities associated with neuro-Behcet disease.

Behcet Syndrome↗
PubMed1995

I-123 MIBG imaging of metastatic carcinoid tumor from the rectum.

I-131 MIBG, a specific radiopharmaceutical agent for scintigraphic imaging and treatment of pheochromocytoma and neuroblastoma may be useful for detection of apudomas. Scintigraphy with I-123 radiolabeled MIBG was performed in a patient with metastatic carcinoid tumor from the rectum. I-123 MIBG scintigraphic findings showed multiple areas of abnormal tumor uptake of hepatic and bone metastases from the rectal carcinoid. Bone scintigraphy demonstrated multiple metastatic lesions. Computed tomography revealed multiple solid tumors of the liver. This report describes accumulation of I-123 MIBG in the liver and bone metastases from the rectal carcinoid. Radioiodine MIBG scintigraphy may be useful for detecting metastatic lesions, for evaluating postoperative recurrence, and also for the treatment of the carcinoid tumor.

3-Iodobenzylguanidine↗