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K Hongo

Publications and source records attributed to K Hongo.

At least 73 records · Page 4Linked to original sources
PubMed1995

Noninvasive cerebral optical spectroscopy: depth-resolved measurements of cerebral haemodynamics using indocyanine green.

To investigate the feasibility of a newly developed, near-infrared optical spectroscopy device, we analysed measurements of the infrared tracer indocyanine green (ICG) using sensors with a single near infrared light source and multiple light detectors. Two ml of ICG dye, 1.0 mg ml-1 in concentration, were injected into the internal carotid artery during cerebral angiography in 14 adult patients. The resultant washout curves were measured bilaterally using sensors with 4 detectors spaced at 10, 20, 30 and 40 mm from the infrared light source on the right side, and 15, 25, 35 and 45 mm from the source for the left side, respectively. Washout curves were analysed to determine the relative amplitude of the ICG absorption signal and deduce each detector's penetration distance. When ICG was injected into the internal carotid artery, relative absorption increased with detector distance from the light source. No substantial difference in attenuation was observed in any of the detectors during external carotid injection of ICG. The resultant information related depth of penetration of the light with source-detector separation distances. The feasibility of the system for measuring cerebral oxygen saturation and haemodynamics noninvasively or monitoring at bedside is discussed.

Adult↗
PubMed1995

The effect of mechanical loading on the response of rat ventricular myocytes to acidosis.

The effect of mechanical loading on the negative inotropic effect of acidosis in isolated rat ventricular myocytes was investigated. The mechanical loading of the myocytes was changed by attaching carbon fibres to the ends of the cell. To monitor intracellular Ca2+ and Na+ concentrations, cells were loaded with fluorescent dyes (fura-2 for Ca2+ and SBFI for Na+) using the acetoxymethyl (AM) esters. Mechanical loading reduced cell shortening by 73.0 +/- 3.5% (mean +/- S.E.M., n = 16) and abbreviated the time course of contraction. CO2-induced acidosis caused a rapid decrease in contraction followed by a slow partial recovery. The percentage changes in contraction were not significantly different in mechanically loaded and unloaded conditions. Mechanical loading had little effect on the time course of contraction during acidosis. Changes in intracellular Ca2+ and Na+ concentrations during acidosis were unaffected by mechanical loading. The mechanical loading conditions of a region of the heart can be modified by ischaemia and the subsequent acidosis. Our results suggest that the response of cardiac muscle to acidosis is not markedly modified by such changes in mechanical loading.

Acidosis↗
PubMed1995

Effect of stretch on contraction and the Ca2+ transient in ferret ventricular muscles during hypoxia and acidosis.

The effect of stretch on cardiac muscle contraction and the Ca2+ transient was studied during hypoxia and acidosis in isolated ferret ventricular muscles. In control conditions, a maintained stretch produced an immediate increase in tension followed by a slow increase in tension and the Ca2+ transient. A stretch between contractions (diastolic stretch) caused only a slow increase in tension and the Ca2+ transient, whereas a stretch during the period of contraction (systolic stretch) produced an immediate increase in tension followed by a small slow increase in tension and the Ca2+ transient. In hypoxia, the immediate percent increase in tension was the same as in control. However, the slow increase was smaller during all three types of stretch. In acidosis, the immediate percent increase in tension was larger than in control. The slow change was the same during maintained stretch. However, the slow increase in tension was smaller during diastolic stretch and larger during systolic stretch. Thus the stretch-dependent increase in contraction is inhibited during hypoxia and modulated by acidosis.

Acidosis↗
PubMed1994

Chaperonin GroE and ADP facilitate the folding of various proteins and protect against heat inactivation.

In the presence of ADP, the molecular chaperones GroEL and GroES from Escherichia coli not only facilitated the refolding of various proteins, but also prevented their irreversible heat inactivation in vitro. Without nucleotides the refolding reactions were arrested by GroEL. Addition of GroES and ADP to the reaction mixture initiated the refolding reactions and the enzyme activities were regained efficiently. The presence of GroE (GroEL and GroES) and ADP also protected against heat inactivation of native enzymes at various temperatures. These findings suggest that in the presence of GroES, nucleotide binding is an important event in the mechanism of GroEL-facilitated protein folding.

Adenosine Diphosphate↗
PubMed1994

Trigeminal sensory innervation on perforators of the circle of Willis in rabbits by wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing.

Distribution patterns of sensory innervation from the trigeminal ganglion to the perforators of the circle of Willis in rabbits were investigated by wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) anterograde tracing. Twenty Japanese white rabbits were anesthetized by inhaling 1% halothane. Using a microsurgical technique, 4 microliters of 2% WGA-HRP in 1 M KCl solution, colored with brilliant blue, was micro-injected into the medial part of the left trigeminal ganglion in 14 animals with a pressure injection system. Another six served as controls to exclude the possibility of labeling non-trigeminal axons. Forty-eight hours later, the perforators in the cisternal and intracerebral segments along with their parent arteries were dissected from the brain according to Dacey's dissecting technique after transcardial perfusion, reacted with the 3,3',5,5'-tetramethyl benzidine method of Mesulam. The results revealed that sensory nerves on the perforators of the circle of Willis were less densely innervated than those on their parent arteries due to the difference in diameter. The posteromedial perforating arteries arising from the P1 segment of the posterior cerebral artery to the tegmentum, posteroventral thalamus and posterior hypothalamus were more prominently and consistently innervated than other perforators. The sensory fibers were seen on the cisternal segment of the perforating arteries. A parallel or twisted pattern was found in the perforators less than 100 microns in diameter, while a meshwork pattern was visualized in the proximal part of some bigger ones. Fine sensory fibers could be traced on the perforators as small as 40 microns in diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Hemifacial spasm and cerebellopontine angle epidermoid: case report and review.

A case with hemifacial spasm with tinnitus due to right cerebellopontine angle epidermoid is reported. The tumour was supposed to have caused the displacement of the part of anterior inferior cerebellar artery in the vicinity of the root exit zone of the ipsilateral facial nerve. Near total removal of the tumour along with microvascular decompression was done and the patient was completely relieved of his symptoms. The incidence of hemifacial spasm due to cerebellopontine angle epidermoid is extremely low. The cause of such an association is discussed and relevant literature is reviewed.

Brain Neoplasms↗
PubMed1994

Vertebrobasilar junction fenestration associated with dissecting aneurysm of intracranial vertebral artery.

BACKGROUND: Vertebrobasilar junction fenestration is considered to be a subtype of fenestration of the proximal basilar artery, which has been described only in autopsy cases. The fenestration associated with a dissecting vertebral aneurysm is extremely rare. CASE DESCRIPTION: A 47-year-old man presented with subarachnoid hemorrhage. The four-vessel angiogram showed a fusiform dilatation with an intimal flap of the left vertebral artery distal to the origin of the posterior inferior cerebellar artery and a fenestration at the vertebrobasilar junction, in which a small limb of the fenestration arising from the distal portion of the left vertebral artery bridged the proximal basilar trunk, while another limb had a large diameter showing the same diameter as the basilar artery. The dissecting aneurysm was treated with body clipping by directly clipping the ruptured portion of the aneurysm via a suboccipital approach in an early operation 48 hours after the ictus. The patient had a good recovery and returned to his work. He is well at a 5-year follow-up. CONCLUSIONS: The relevant angiographic features of the vertebrobasilar junction fenestration and the surgical treatment of such associated aneurysms are discussed.

Aortic Dissection↗
PubMed1994

Cytoplasmic free Mg2+ in rat ventricular myocytes studied with the fluorescent indicator furaptra.

To estimate cytoplasmic Mg2+ concentration ([Mg2+]i), ventricular myocytes enzymatically isolated from rat hearts were loaded with the fluorescent indicator, furaptra, and the fluorescence signals of single quiescent myocytes were measured at 32 degrees C. The excitation spectrum of furaptra measured in the myocytes was well-fitted by the spectra obtained in vitro; thus it was possible to calibrate the fluorescence signal in terms of [Mg2+]i. The analysis implied that about 20% of the indicator molecules were Mg(2+)-bound. Considering that the indicator likely reacts with Mg2+ with a larger KD value in cytoplasm than in vitro (by a factor of 1.2-2 as suggested for mouse and frog skeletal muscles), the [Mg2+]i for the resting single myocytes was estimated to be within 0.8-1.3 mM. Superfusion with a high extracellular Mg2+ concentration (20 mM) caused a slow and slight elevation in [Mg2+]i over a period of a few hours. Other experimental interventions, including application of a low extracellular Na+ concentration and isoproterenol, and CO2 acidosis, did not cause a detectable change in [Mg2+]i, whereas the application of an uncoupler, a blocker of oxidative phosphorylation in mitochondria, caused a rapid and large increase in [Mg2+]i. It is suggested that the [Mg2+]i is tightly maintained at around 1 mM, unless intracellular ATP is depleted.

Animals↗
PubMed1994

Effects of a newly synthesized dihydropyridine, NZ-105, on intracellular Ca transients and tension in ferret ventricular muscles.

We investigated the effects of a newly synthesized dihydropyridine (DHP) derivative (NZ-105) on intracellular Ca transients and contraction in ferret ventricular muscles, using the aequorin method. Low concentrations of NZ-105 (10(-9)-10(-7) M) showed no significant effects on the light signal of aequorin and tension in twitch. High concentrations of NZ-105 (10(-6)-10(-5) M) inhibited the peaks of the light signal and tension without altering their time courses. The relation between the peaks of the light signal and tension in twitch, measured in solutions with varying Ca2+ concentrations, was shifted to the left by NZ-105. The relation between [Ca2+]i and tension measured in tetanic contraction was also shifted to the left by NZ-105. These results suggest that the inhibitory effect of NZ-105 on contraction in mammalian cardiac muscle is curtailed by an increase in Ca sensitivity of the contractile elements.

Animals↗
PubMed1993

Tension and intracellular calcium transients of activated ferret ventricular muscle in response to step length changes.

To elucidate the effects of mechanical constraints on the (Ca2+) affinity of cardiac troponin C, we studied the relationships among the myoplasmic Ca2+ concentration ([Ca2+]i), tension and length in steadily activated intact cardiac muscle. The Ca2+ sensitive photoprotein, aequorin, was micro-injected into cells of ferret right ventricular papillary muscles to monitor the [Ca2+]i. The muscle was then steadily activated with ouabain (10(-4) M)(ouabain contracture) or high frequency stimuli in the presence of ryanodine (5 microM)(tetanic contraction); the tension and aequorin light (AL) transients in response to a step length change were then analyzed. The tension transient response to either the stretch or release in length was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in the ouabain contracture. The transient AL response was also oscillatory, the time course of which corresponded exactly to that of the tension transient response, though no detectable changes in AL were observed at the initial phase of the stretch response. The increase in AL corresponded exactly to the decrease in tension, likewise the decrease in AL to the increase in tension. The steady level of AL after release was decreased in ouabain contracture, but was increased in tetanic contraction. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e., the cross-bridge attachment) and decreased with a decrease in tension (i.e., the cross-bridge detachment), and that the myoplasmic calcium concentration is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.

Aequorin↗
PubMed1993

Angiographic differentiation of carotid cave aneurysms from ventral paraclinoid carotid aneurysms of Nutik type.

Although it appears that carotid cave and ventral paraclinoid carotid aneurysms are different types of internal carotid artery (ICA) aneurysms, it can be difficult to differentiate the two on the basis of angiograms, because their locations are very close. The purpose of this study was to review the angiographic findings in 21 cases with carotid cave aneurysms and 7 cases with ventral paraclinoid carotid aneurysms of less than 15 mm in diameter (Nutik aneurysm) operated upon in our unit during the last 14 years, and to discuss the difference between the two groups. The results showed that in the anteroposterior view of the angiogram, all carotid cave aneurysms projected medially in semicircular, or berry shape, while only slight medial projection was noted in 3 cases with Nutik aneurysm, the remainder being superimposed on the ICA. In the lateral view of the angiogram, we found that in 6 of the 7 Nutik aneurysms there was a space between the axilla (area inside the genu of the ICA) and the anterior or anteroinferior wall of the aneurysm. This space was absent in all carotid cave aneurysms since these aneurysms projected inferoposteriorly from the genu of the ICA. It is concluded that predominant medial projection in the anteroposterior view and absence of space in the lateral view are two characteristic features of carotid cave aneurysms which can be used to differentiate them from most Nutik aneurysms.

Adult↗
PubMed1993

Indications and limitations for CT-guided stereotaxic surgery of hypertensive intracerebral haemorrhage, based on the analysis of postoperative complications and poor ability of daily living in 158 cases.

The authors have studied the indications and limitations for computerized tomography (CT)-guided stereotaxic surgery (CTGS Surgery) of hypertensive intracerebral haematomas (ICH), based on the analysis of 158 patients in our institutions. Of 158 patients, 120 had putaminal haemorrhage, 21 thalamic, 14 subcortical and 3 in other locations. The patients ranged in age from 37 to 82 years (average 60). Haematoma volume ranged from 8 to 140 ml (average 43). Eleven patients in the series worsened postoperatively because of rebleeding in 6 cases, cerebral infarction in 2, and unknown causes in the remaining 3 cases. Seven of the 11 patients pre-operatively had untreated hypertension and 3 had mild liver dysfunction without major haemorrhagic tendency. Most postoperative complications were seen in older patients and in those with severe neurological deficit or chronic disease. All these cases ended in poor outcome. From our study, we propose three indications for CTGS Surgery: absolute, aggressive and passive indications. The absolute indication is applied to those who would have been operated on by conventional open surgery. The aggressive indication is for those with mild neurological deficit so that early rehabilitation can be started to regain higher cerebral function. The passive indication is for elderly patients and those with severe neurological deficit or chronic disease. This indication must be decided carefully because poor outcome is likely.

Activities of Daily Living↗
PubMed1993

Carbamazepine-induced skin rash in children with epilepsy.

The clinical and epidemiological findings in children with epilepsy who experienced skin rashes induced by carbamazepine (CBZ) were prospectively evaluated. Thirty-three (9.9%) of 335 patients who received CBZ therapy experienced a skin rash. Seven had diffuse erythema, 13 miliary exanthema, 11 maculopapular or speckled reddish rash, 3 petechiae, and 2 mucocutaneous syndrome. A skin rash was more frequent in older children (over 6 years old). The skin rashes appeared soon after initiation of the therapy, i.e., from the 8th to 60th day (mean: 14.3 +/- 9.6 days) after the start of CBZ therapy and disappeared within a few days after discontinuation of the therapy. Haematological abnormalities (30.3%), such as leucocytopenia and thrombocytopenia, and hepatic dysfunction (27.3%) sometimes appeared concomitantly with the skin rash. CBZ is an effective and safe antiepileptic drug, but careful management is necessary on initiation of the therapy.

Adolescent↗
PubMed1993

Calcium antagonists for the treatment of vasospasm following subarachnoid haemorrhage.

Cerebral vasospasm and/or delayed ischaemic state following subarachnoid haemorrhage still remain unsolved serious problems. With the development and introduction of calcium antagonists as well as the advances in perioperative management, however, the clinical outcome has much improved in recent years. Among such drugs, nimodipine and nicardipine are those, of which effectiveness on the vasospasm or delayed ischaemic changes was demonstrated by several double-blind placebo-controlled studies. This paper reviews the current status of the calcium antagonists used in the management of subarachnoid haemorrhage, focusing mainly on the clinical study.

Animals↗
PubMed1993

Comparison of spontaneously released endothelium-derived relaxing factor in cerebral and extracerebral arteries in rabbits.

To investigate regional differences in spontaneously released endothelium-derived relaxing factor (EDRF), a bioassay of spontaneously released EDRF was performed on rabbit basilar, ear, common carotid and thoracic arteries using an isometric tension measurement technique and a measurement of cyclic guanosine monophosphate (cGMP) content in the vascular smooth muscle. The amount of spontaneously released EDRF was higher in the basilar artery than in any other arteries examined (p < 0.01). The levels of cGMP were 57.3 +/- 4.4 (n = 7) in basilar, 26.5 +/- 4.3 (n = 6) in ear, 24.5 +/- 2.3 (n = 11) in common carotid, and 30.3 +/- 3.8 pmol/g tissue (n = 8) in thoracic artery with endothelium, while endothelium-denuded arteries showed 24.2 +/- 6.6 (n = 5), 17.5 +/- 5.1 (n = 6), 20.1 +/- 2.9 (n = 7) and 14.4 +/- 2.3 pmol/g tissue (n = 8) in the same order. Haemoglobin (10(-5) M, incubated with the artery for 5 min, significantly reduced the level of cGMP in all vessels with endothelium: 35.3 +/- 4.4 (basilar), 16.0 +/- 2.1 (ear), 14.0 +/- 1.9 (common carotid) and 8.7 +/- 1.2 pmol/g tissue (thoracic artery). Since endothelium-dependent relaxation is associated with a rise in the cGMP content of the smooth muscle cell, the data of cGMP measurement in addition to the bioassay of spontaneously released EDRF in tension measurement suggests that the spontaneous release of EDRF is much greater in the basilar artery than in extracerebral arteries. It is concluded that the intensity of the spontaneously released EDRF is relatively higher in the intracerebral artery than in the extracerebral artery.

Acetylcholine↗
PubMed1993

Alterations in contractile properties and Ca2+ transients by beta-and muscarinic receptor stimulation in ferret myocardium.

1. To clarify the mechanism which regulates the time course of twitch tension when beta- and muscarinic receptors are stimulated, intracellular Ca2+ transients, Ca2+ sensitivity of the contractile element and the cross-bridge cycling rate (CCR) were measured in ferret ventricular muscles. 2. Isoprenaline (Iso; 0.1 microM) increased peaks of Ca2+ transients measured with aequorin and tension, and abbreviated the time courses of both signals. Addition of acetylcholine (ACh; 0.01-1 microM) to the Iso-treated preparation dose dependently decreased the peaks of both signals and restored the time course of Ca2+ transients. However, the time course of tension was not recovered by the addition of ACh, and the relaxation time in particular, was further shortened by ACh. Carbachol (1 microM) applied to the Iso-treated preparation yielded similar results. 3. [Ca2+]i and tension at a quasi-steady level of tetanic contraction, which was produced by ryanodine (5 microM) and repetitive stimulation, were measured and Ca2+ sensitivity of the contractile element was estimated. Iso (0.1 microM) decreased the Ca2+ sensitivity and the addition of ACh (1 microM) completely recovered it to the control level. 4. In order to measure CCR, the perturbation analysis method was applied to steady-state tension of tetanic contraction. The CCR was not altered even when the tetanic tension level was decreased to 50% by decreasing [Ca2+]o. Iso (0.1 microM) slightly decreased the tetanic tension level and increased the CCR from 2.73 to 3.25 Hz. The effect of Iso was observed when the Iso-decreased tension was recovered by an increase in [Ca2+]i. The addition of ACh (1 microM) recovered the CCR which was increased by Iso, to the control level. Atropine (10 microM) blocked the effect of ACh, and carbachol (1 microM) restored the CCR increased by Iso to the control level. 5. The time course of Ca2+ transients, Ca2+ sensitivity and CCR were antagonistically regulated by beta- and muscarinic receptor stimulation, but the time course of tension did not parallel the changes in these parameters. Therefore, these results suggest that the time course of tension, particularly the relaxation time, is not determined by the time course of Ca2+ transients, Ca2+ sensitivity and the CCR, and that other factors might be involved in the regulation of the time course of tension when beta- and muscarinic receptors are stimulated.

Acetylcholine↗