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Biomedical subjects

I Kitano

Publications and source records attributed to I Kitano.

At least 19 recordsLinked to original sources

Effect of endoplasmic Ca2+-ATPase inhibitors on cochlear potentials in the guinea-pig.

The effect of endoplasmic Ca2+-ATPase inhibitors on cochlear potentials was examined in the guinea-pig. Perilymphatic perfusion with thapsigargin (10[-6] M) produced a significant decrease in the amplitudes of cochlear microphonics, negative summating potential and compound action potential, and a significant prolongation of N1 latency with no change in the endocochlear potential. These changes were all dose dependent. Another endoplasmic Ca2+-ATPase inhibitor, cyclopiazonic acid (10[-5] M), produced the same effects as thapsigargin on cochlear potentials. These results suggest that endoplasmic Ca2+-ATPase inhibitors may have inhibitory functions on cochlear potentials.

Animals

The effect of forskolin on the sound-evoked potentials in the guinea pig cochlea.

The effect of forskolin (FSK) on cochlear sound-evoked potentials was examined in the guinea pig. The perfusion of the scala vestibuli (SV) with FSK (2 x 10(-4) M) produced a significant increase in the amplitude of negative summating potential (- SP) with no change in cochlear microphonics (CM) amplitude, and a significant decrease in the amplitude of compound action potential (CAP) with a significant prolongation of N1 latency and a 20 dB CAP threshold elevation. The results lead us to speculate that FSK-induced changes may be involved in the transient formation of endolymphatic hydrops.

Animals

Failure of forskolin to elevate the endocochlear potential in experimental endolymphatic hydrops of the guinea pig.

The effect of forskolin (FSK) on the endocochlear potential (EP) in scala media (SM) was examined in experimental endolymphatic hydrops of the guinea pig. Two weeks after obliteration of the endolymphatic sac the EP of hydroptic ears and that of the contralateral control ears were measured by means of microelectrodes. The perfusion of scala vestibuli (SV) with FSK (200 microM) produced EP elevation in the contralateral control ears but failed to do so in the experimental hydroptic ears. Histological examination of experimental endolymphatic hydrops showed mild hydrops with intact appearance of outer and inner hair cells, and the stria vascularis. The mechanism underlying the failure of FSK to elevate the EP in experimental endolymphatic hydrops is discussed.

Animals

Leriche syndrome. Surgical procedures and early and late results.

During the past thirteen years, 29 patients underwent surgical intervention for Leriche syndrome. Fifteen patients (aged forty-two to seventy-two years, average 60.7 years) underwent anatomical bypass, and 9 of them whose thrombus was confined to the infrarenal aorta received a routine graft insertion. In the other 6 whose thrombus extended to the level of the renal arteries, an open thrombectomy of the juxtarenal aorta was first performed through a transection of the infrarenal aorta under renal ischemia (4-14 minutes, average 7). Twelve elderly or high-risk patients (aged sixty-eight to eighty-four years, average 75.3 years) underwent an axillobifemoral bypass, and another 2 (fifty-eight and sixty years old, respectively) who had been operated on at an earlier time received an ascending aortobifemoral bypass. In cases of anatomical bypass, no graft has occluded and all patients but 1, who died of cerebral infarction, have an active life now. In cases of extraanatomical bypass, 5 of the 28 grafts occluded and only 6 patients have survived. The other 8 patients died of malignancy, atherosclerotic complications, or unknown causes. The 10-year survival rate was 92.9% and 29.5% in the anatomical bypass and extraanatomical bypass group, respectively. In Leriche syndrome, anatomical bypass is preferred to extraanatomical bypass if conditions permit. In the juxtarenal type, an open thrombectomy under renal ischemia is mandatory for anatomical bypass, and a transection of the infrarenal aorta facilitates this procedure. Because the patients with Leriche syndrome are elderly and harbor arteriosclerotic lesions, a careful follow-up is mandatory.

Adult

Craniofacial morphology of conotruncal anomaly face syndrome.

OBJECTIVE AND DESIGN: The conotruncal anomaly face syndrome (CTAF) comprises congenital heart disease and dysmorphic face, and is frequently associated with cleft palate or hypernasality. There have been many discussions about the overlap with velocardiofacial syndrome (VCF). The aim of this study was to clarify the craniofacial characteristics of CTAF patients by clinical examination, and photogrammetric and cephalometric analyses, and to clarify the differences compared to published data on VCF. RESULTS: The facial features of CTAF included hypertelorism, small palpebral fissures, upward slanting of palpebral fissures, bloated eye lids, low nasal bridge, small mouth, open mouth at rest, and malformed auricles. Cephalometric features included bialveolar protrusion, small gonial angle, backward rotation of the mandibular ramus, and labial inclination of the maxillary incisors. An acute cranial base angle was also noted. These results differed from those of VCF. There were, however, no obvious pathognomonic findings for the differential diagnosis between CTAF and VCF. CONCLUSIONS: Considering these findings, use of CATCH 22, the inclusive classification of cardiac anomalies, cleft palate, and dysmorphic face may be of value for the clinical understanding in these patients.

Alveolar Process

[A successful emergency reoperation of thrombosed CarboMedics valve in the mitral position].

We report a successful emergency reoperation of a thrombosed CarboMedics valve five years after the original implantation of the prosthesis. A 53-year-old mentally retarded woman suffered acute heart failure due to a thrombosed CarboMedics valve, which was caused by inadequate control of anticoagulants. The patient was reoperated on immediately after thrombolytic therapy failed to show an improvement in leaflets' excursion. The excised prosthesis demonstrated that organized thrombi originating at both sides of the hinge portions extended to the atrial side of one of the leaflets. The bileaflet valve is supposed to prohibit catastrophic heart failure by preventing simultaneous malfunction of both leaflets. However, we believe that prompt surgical treatment is essential even for the thrombosed bileaflet valve, because a thrombus originating in the hinge area seems to develop into a fatal simultaneous malfunction of both leaflets.

Emergencies

[Surgical results of coronary artery bypass grafting in patients older than 75 years].

We studied 19 patients, all older than 75 years of age, who had isolated coronary artery bypass grafting (CABG) from January 1990 to December 1996. Clinical characteristics, hospital mortality and long-term survival were compared between this elderly group (> or = 75 years) and a younger group (60-74 years) in which 130 consecutive patients underwent the same procedure during the same period. There were no differences of coronary risk factors, renal function, respiratory function and ejection fraction between the two groups. The incidences of left main trunk stenosis (> or = 50%) and three-vessel-disease were more common in the elderly group, but the difference between the groups was not statistically significant. Preoperative use of an intra-aortic balloon pump was more frequent in the elderly group (p < 0.01). The hospital mortality rate of 31.6% for the elderly group was significantly higher than that of 5.4% for the younger group (p < 0.01). However, of particular note is that the 30-day hospital mortality was half (15.8%) and that three of six (50%) hospital deaths occurred between 35 and 148 days. These patients died from acute respiratory failure subsequent to aspiration pneumonia, ruptured dissecting aortic aneurysm, and ischemic enterocolitis. This difference between the 30-day hospital mortality rate (15.8%) and hospital mortality rate (31.6%) emphasizes the influence that postoperative complications can have on subsequent outcome. Of 136 hospital survivors (123 in the younger group and 13 in the elderly), 98% have been followed for a mean of 32 months. The 4-year survival was 60 +/- 22% for hospital survivors of the elderly group. It compares favorably with that for the younger group (85 +/- 5%), and with previously reported data. We conclude that despite a significantly increased hospital mortality, good long-term survival can be realized after CABG, even in patients older than 75 years.

Age Factors

[Hypoplasia of the left internal carotid artery associated with anterior communicating aneurysm, intercarotid anastomosis and left rete carotidis].

Hypoplasia of the internal carotid artery with cerebral aneurysm is extremely rare. The authors report a case of hypoplasia of the left internal carotid artery associated with anterior communicating aneurysm, intercarotid anastomosis and left rete carotidis. A 45-year-old man was admitted to Minamata Municipal Hospital because of severe headache and disturbance of consciousness. CT scan showed subarachnoid hemorrhage with intracerebral hematoma. Right carotid angiogram showed the anterior communicating aneurysm arising from the right A1-A2 corner and intercarotid anastomosis on the cavernous portion. The distal part from the C4 portion of the left internal carotid artery was revealed through these anastomotic vessels. Left carotid angiogram showed hypoplasia of the left internal carotid artery and unusual tortuous collateral vessels arising from the left internal maxillary artery, ascending pharyngeal artery and its branches to the left internal carotid artery. These collateral vessels are called "rete carotidis" or "rete mirabile caroticum." Both the intercarotid anastomosis and rete carotidis are unusual anastomotic vessels and are considered not to appear during normal development of the cranial circulation in humans. CT scan with skull base bone target image showed hypoplasia of the left carotid canal. In this case, the change in cranial circulation due to hypoplasia of the internal carotid artery was considered one of the main factors in the development of these unusual anastomotic vessels and cerebral aneurysm.

Carotid Arteries

The action of substance P methyl ester on cochlear potentials in the guinea pig.

The action of the substance P agonist, substance P methyl ester (SPME) on cochlear potentials was examined in the guinea pig. Previous studies have shown that SPME is a selective agonist for neurokinin 1 (NK1) receptor. Perfusion with SPME at a concentration of more than 10(-6)M produced an increase in the amplitudes of the compound action potential and negative summating potential in a dose-dependent manner. N1 latency showed a tendency to be shortened, but this change was not significant. Amplitudes of the cochlear microphonics and endocochlear potential remained unchanged. Substance P fragment 7-11, an inactive analogue, produced no changes in the cochlear potentials. In contrast, the substance P antagonist [D-Pro2, D-Trp7,9]-SP blocked the action of SPME on the cochlear potentials. These results suggest that substance P may modulate neurotransmission through NK1 receptors in the cochlea.

Action Potentials

Primary intracranial plasma-cell granuloma: a case report and review of the literature.

BACKGROUND: Plasma-cell granulomas, which are characterized by the non-neoplastic proliferation of plasma cells, are primarily found in the lungs and upper respiratory tracts, and are extremely rare in the central nervous system. METHODS: An intracranial tumor of an 11-year-old boy was evaluated by histologic and radiologic examination. RESULTS: An 11-year-old boy had a 2-month history of mild headache and nausea. A computed tomography scan showed a round, slightly high-density mass surrounded by marked edema in the left frontal lobe. On magnetic resonance imaging (MRI), the mass had a slightly high signal intensity on the T1-weighted image and marked low signal intensity on the T2-weighted image. It was heterogenously enhanced with gadolinium-DTPA. Microscopic examination demonstrated a non-neoplastic mixed cell population with a predominance of plasma cells. Immunohistochemical staining revealed that it was characterized by a polyclonal plasma cell population. CONCLUSION: Our extensive search of the literature indicated this to be the ninth reported case of intracranial plasma cell granulation. The MRI was very useful for evaluating the extent of the intracranial lesions. The tumor was removed surgically and did not recur during a 2-year follow-up with no radiation therapy.

Brain Diseases

Role of endolymphatic anion transport in forskolin-induced Cl- activity increase of scala media.

To determine the role of anion transport in the forskolin-induced Cl- increase of scala media (SM), effects of forskolin on the EP (endocochlear potential) and Cl- activity (ACl) in SM were examined with double-barrelled Cl(-)-selective microelectrodes. The experiments were carried out on guinea pig cochleae, using a few anion transport inhibitors: IAA-94 for a Cl- channel blocker, bumetanide (BU) for an Na+/K+/2Cl- cotransport blocker, and SITS and DIDS for Cl-/HCO3- exchange blockers. The application of forskolin (200 microM) into scala vestibuli (SV) caused a 20 mEq increase of endolymphatic ACl and a 15 mV elevation of EP, and IAA-94 with forskolin completely abolished these responses. Although each application of BU, SITS or DIDS did not completely suppress EP elevation, the concurrent application of these inhibitors completely suppressed EP with endolymphatic ACl increase. The results indicate the involvement of Cl- channels, Na+/K+/2Cl- cotransport and Cl-/HCO3- exchange in forskolin-induced increase of ACl and EP. The role of adenylate cyclase activation and Cl- transport in endolymph homeostasis was discussed.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid

The effect of protein kinase C stimulator and inhibitor on cochlear potentials in the guinea pig.

To determine a possible role of protein kinase C (PKC) in the cochlear, the effects of a PKC stimulator (phorbol-12-myristate-13-acetate; PMA), an inactive analogue of PKC stimulator (4 alpha-phorbol-12,13-didecanoate; 4 alpha-PDD) and a PKC inhibitor (D-sphingosine) on cochlear potentials were examined in the guinea pig. The perilymphatic perfusion with PMA (3 x 10(-6) M) produced an increase in compound action potential (CAP) amplitude and no change in N1 latency, the amplitudes of negative summating potential (-SP), cochlear microphonics (CM) and endocochlear potential (EP). The perfusion with 4 alpha-PDD (3 x 10(-6) M) did not change the sound-evoked cochlear potentials and the EP. The perfusion with D-sphingosine (10(-5) M) produced a decrease in CAP amplitude and no change in N1 latency and the amplitudes of -SP, CM and EP. The results suggest that PKC may be involved in the mechanism underlying the CAP generation.

Acoustic Stimulation

Role of ATP-sensitive K+ channels in anoxia-sensitive negative potential of endolymph.

To investigate the possible role of the ATP-sensitive K+ channels (KATP channels) in the generation of the anoxia-sensitive negative potential (ASNP), the effects of the treatment with glybenclamide and diazoxide on the endocochlear potential (EP) and K+ activity (AK) in the scala media were examined with double-barrelled K(+)-selective microelectrodes. The experiments were carried out in guinea pig cochleae, using glybenclamide as a KATP channel blocker and diazoxide as a KATP channel opener. Perilymphatic perfusion of glybenclamide decreased the amplitude of the ASNP and shortened its duration, whereas perfusion of diazoxide increased ASNP amplitude and prolonged its duration. Glybenclamide enhanced the decrease of endolymphatic AK by anoxia, whereas diazoxide suppressed this AK decrease. The results suggest that KATP channels may be involved in the generation of the ASNP.

Adenosine Triphosphate

Treatment of intracranial nongerminomatous malignant germ cell tumors producing alpha-fetoprotein.

We treated 10 patients with intracranial nongerminomatous malignant germ cell tumors producing alpha-fetoprotein between 1969 and 1992. Two patients were treated with radiotherapy (RT) only (RT group), and three were treated with RT and cisplatin plus vinblastine plus bleomycin therapy with or without surgery (cisplatin plus vinblastine plus bleomycin group). The most recently treated five patients received cisplatin plus etoposide (PE) therapy with or without RT and/or surgery (PE group). The level of alpha-fetoprotein in serum was elevated in all 10 patients. In the PE group, PE therapy consisted of cisplatin (20 mg/m2) and etoposide (60 mg/m2) daily for 5 days (one course) given two or three times at 4-week intervals and then once every 4 months; the patients received three to six courses (mean, 4.2 courses). In the RT group (n = 2), one patient died 3 months after diagnosis and the other died at 12 months. In the cisplatin plus vinblastine plus bleomycin group (n = 3), complete remission was obtained in one patient, but the other two patients died 12 and 24 months after diagnosis. In contrast, in the PE group (n = 5), complete remission was obtained in all patients who are all currently alive without recurrence, at 35 to 71 months (average, 53.6 mo) after diagnosis. The results indicate that multidisciplinary treatment including combination chemotherapy with cisplatin and etoposide with or without surgery and/or RT is highly effective in the treatment of patients with alpha-fetoprotein-producing intracranial nongerminomatous malignant germ cell tumor.

Adolescent

The effect of adenosine on cochlear potentials in the guinea pig.

The effect of adenosine on cochlear potentials was examined in the guinea pig. Perilymphatic perfusion with 10(-4) M adenosine produced a significant decrease in the amplitudes of cochlear microphonics, negative summating potential (-SP) and compound action potential (CAP) and significant prolongation of N1 latency with no change in the endocochlear potential. The decreases in the amplitudes of -SP and CAP caused by adenosine were dose-dependent. Perilymphatic perfusion with an inactive analogue, 8-bromoadenosine, produced no changes in the cochlear potentials. The A1-receptor agonist, 2-chloro-adenosine, produced a similar change in cochlear potentials to adenosine, while no changes were produced by the A2-receptor agonist, 5'-(N-ethylcarboxamido)-adenosine. These results suggest that adenosine may have a modulatory function through an A1 receptor in the cochlea.

2-Chloroadenosine

The pattern of palatal rugae in submucous cleft palates and isolated cleft palates.

The early diagnosis of submucous cleft palate is important. In children too young to tolerate nasendoscopy and videofluoroscopy the diagnosis depends on the clinical history and intraoral examination. We have studied the pattern of the hard palate rugae to investigate their possible diagnostic significance. Maxillary dental casts were obtained from 16 patients with submucous cleft palate, 17 patients with isolated clefts of the secondary palate, and 10 non-cleft controls. The hard palate mucosa had a unique feature in 14 (87.5%) of the submucous cleft palates: one or more of the palate rugae curved towards the region of the bony notch in the posterior border of the hard palate. The 2 cases without this rugae pattern did not have a detectable bony notch. In 100% of the isolated cleft palate cases, one or more of the rugae curved towards the anterior end of the cleft. This feature was not seen in any of the non-cleft controls. We consider this rugae pattern to be an additional diagnostic feature of submucous cleft palate.

Child

Isolated oculomotor nerve palsy following midbrain infarction.

A 62 year-old male patient presented with isolated oculomotor nerve palsy following a small infarction of the medial ventral midbrain, documented by magnetic resonance imaging. There was a 12-year history of hypertension, but no diabetes mellitus. Angiography revealed atherosclerosis of the paramedian mesencephalic arteries. Magnetic resonance imaging may be useful in patients with small brain stem infarctions.

Cerebral Angiography

Failure of forskolin to elevate the endocochlear potential in kanamycin-poisoned animals.

The effect of forskolin (FSK) on the endocochlear potential (EP), K+ activity (AK), Na+ activity (ANa) and Cl- activity (ACl) in scala media (SM) was compared between normal and kanamycin (KM)-poisoned guinea pigs by means of double-barrelled ion-selective microelectrodes. The perfusion of the scala vestibuli (SV) with FSK (200 microM) produced EP elevation in normal animals whereas FSK failed to do it in KM-poisoned animals. FSK increased ACl of SM with no significant change in AK and ANa of SM in both groups of animals. Histological examination of KM-poisoned animals showed damaged outer and inner hair cells with an intact appearance of the stria vascularis. The mechanism underlying the failure of FSK to elevate the EP in KM-poisoned animals is discussed.

Animals