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Biomedical subjects

F Mori

Publications and source records attributed to F Mori.

At least 55 records · Page 3Linked to original sources
PubMed2001

"Natural histories" of mitral valve prolapse. Influence of patient selection on cardiovascular event rates.

BACKGROUND: In previous studies the reported incidence of cardiovascular events among mitral valve prolapse patients has differed more than 10 fold. We endeavored to determine the relation between the clinical features and mode of ascertainment of mitral valve prolapse and the resulting event rate. METHODS: Between January 1979 and August 1996, 275 patients (129-47% men, 146-53% women, mean age 43 +/- 19 years), were followed for a mean of 98 months after evaluation in a referral center for valvular heart disease. Comparative data were obtained from a separate, less selected population consisting of 316 patients. RESULTS: A total of 65 events occurred (2.9/100 patient-years): 46 (2.0/100 patient-years) mitral surgery, 12 cardiac deaths (0.5/100 patient-years), 6 neurologic ischemia (0.26/100 patient-years), and 1 infective endocarditis (0.04/100 patient-years). The overall event rate varied significantly according to demographic, clinical and echocardiographic variables (all p < 0.0001). It was higher among males (odds ratio-OR 2.1), subjects > or = 45 years of age (OR 14.7), those with a holosystolic murmur (OR 25.9), an enlarged left ventricle (OR 13.5) or left atrium (OR 34.9) and those with 3-4+ mitral regurgitation at color Doppler echocardiography (OR 40.0). It was lower in those with an audible mid-systolic click (OR 0.05). These ORs closely resembled those we reported previously in a less selected population. At multivariate analysis, male gender (p = 0.013), severe Doppler mitral regurgitation (p = 0.0048), and left atrial enlargement (p = 0.046) were all independent predictors of events. CONCLUSIONS: In a population of mitral valve prolapse patients, including many with significant mitral regurgitation at baseline, we identified similar predictors of events but an overall event rate nearly 3 times higher than that we previously reported for relatively unselected patients or family members in New York City (1/100 patient-years). Therefore, the impact of patient selection on the prevalence of mitral regurgitation, older age and male gender strongly affects the adversity of the "natural history" of mitral valve prolapse.

Adolescent↗
PubMed2001

Cardiac contusion in blunt chest trauma: a combined study of transesophageal echocardiography and cardiac troponin I determination.

BACKGROUND: The role of cardiac troponin I (cTnI) is well established in acute myocardial ischemia. However, its role in myocardial contusion remains to be clarified. Since transesophageal echocardiography (TEE) appears, at present, to be the best method for the diagnosis of myocardial contusion, the aim of this study was to measure the concentration of cTnI in patients with blunt chest trauma studied using TEE. METHODS: Thirty-two patients (27 males, 5 females, mean age 44+/-20 years), admitted to the Trauma Center of our Institution with clinical and/or radiological signs of acute blunt chest trauma, underwent biplane TEE within 24 hours of injury; serial blood samples were taken to measure cTnI levels (normal values < 0.4 ng/ml), using fluorimetric enzyme immunoassay. RESULTS: Abnormal levels of cTnI were found in 17 patients (53%): 7 patients had levels of cTnI between 0.4 and 1 ng/ml, whereas 10 patients had levels > 1 ng/ml. Segmental wall motion abnormalities consistent with myocardial contusion could be identified by echocardiography in 6/10 patients with cTnI levels > 1 ng/ml (60%) but in no patients with normal cTnI levels or with titers between 0.4 and 1 ng/ml; mean cTnI levels showed a significant difference between the two groups of patients with and without echocardiographic signs of myocardial contusion (2.6+/-1.6 vs 0.6+/-1.4 ng/ml, p < 0.001). CONCLUSIONS: Abnormal titers of cTnI suggesting myocardial contusion may be found in more than half of patients with blunt chest trauma; however, myocardial injury can be detected by TEE only for cTnI levels > 1 ng/ml; cTnI concentrations ranging between 0.4 and 1 ng/ml might be indicative of myocardial microlesions, not detectable by echocardiography, even if TEE is used; cTnI assay could therefore be suggested as a screening test before performing TEE after blunt chest trauma.

Adult↗
PubMed2001

Bipedal locomotion by the normally quadrupedal Japanese monkey, M. Fuscata: strategies for obstacle clearance and recovery from stumbling.

This study explored how the normally quadrupedal Japanese monkey adjusts to treadmill perturbations, when trained to walk bipedally. The monkey was required to use the left hindlimb to clear an obstacle that was fixed on the left side of a treadmill belt. The monkey either cleared the obstacle (CL: cleared locomotion), or stumbled over it (SL: stumbled locomotion). For CL, it changed its left hind limb's kinematics according to the obstacle's height and position relative to the left foot. In SL, the monkey used a "defensive posture", which included a rapid lowering of the right foot and forelimb movements, to stabilize the perturbed posture and thereby prevent falling. Then, with powerful extensions of its lower limb joints, the monkey raised its center-of-mass to the appropriate level for continuation of normal bipedal walking. The results show that M. Fuscata recruited both anticipatory and reactive neural mechanisms to accommodate to the obstacle.

Animals↗
PubMed2000

A di-synaptic projection from the lateral cerebellar nucleus to the laterodorsal part of the striatum via the central lateral nucleus of the thalamus in the rat.

We have examined a cerebello-thalamo-striatal pathway from the lateral cerebellar nucleus (LCN) to the laterodorsal part of the striatum (LDS) through the central lateral nucleus (CL) using light and electron microscopy through the employment of a combination of anterograde and retrograde tracing techniques. Biotinylated dextran amine (BDA) was injected into the unilateral LCN, and used as an anterograde tracer. Cholera toxin B subunit (CTb), used for light microscopy, and wheat germ agglutinin-horseradish peroxidase (WGA-HRP), used for electron microscopy, were injected into the contralateral LDS as retrograde tracers. Light microscopic analysis showed a good overlap of the distribution of BDA-labeled axon terminals and CTb-labeled neurons in the middle third of the CL in both dorsoventral and rostrocaudal axes on the LDS injection side. Electron microscopy confirmed the presence of direct synaptic contacts between BDA-labeled terminals and WGA-HRP-labeled dendrites in the CL.

Animals↗
PubMed2000

A novel class of highly potent and selective A1 adenosine antagonists: structure-affinity profile of a series of 1,8-naphthyridine derivatives.

A series of 1,8-naphthyridine derivatives (12-36), bearing a phenyl group in position 2 and various substituents in positions 4 and 7, were synthesized in an attempt to obtain potent, selective antagonists for the A1 adenosine receptor subtype. The compounds were tested to evaluate their affinity for A1 compared with A2A and A3 adenosine receptor subtypes. In binding studies in bovine brain cortical membranes, most of the compounds showed an affinity for A1 receptors in the low nanomolar range and two in the subnanomolar range with an interesting degree of A1 versus A2A and A3 selectivity. Comparison of the 4-substituted derivatives indicated that 4-OH substitution, with a 4-quinoid structure, causes an increase in the A1 and A2A affinity and generally also in A1 selectivity. The kind of substitution in position 7 can greatly modulate the affinity: the most interesting substituents in this position seemed to be electron-withdrawing groups; in particular the 7-chloronaphthyridine 25d showed a remarkable selectivity (A2A/A1 ratio of 670, A3/A1 ratio of 14,000) associated with a higher A1 affinity (Ki = 0.15 nM). NMR studies on these compounds 12-36 indicated that the 4-OH-substituted ones prefer the tautomer in which the oxygen in position 4 is in the quinoid form and the nitrogen in position 1 is protonated. Theoretical calculations are in agreement with the NMR data.

Adenylyl Cyclases↗
PubMed2000

Developmental changes in expression of the three ryanodine receptor mRNAs in the mouse brain.

Ryanodine receptors (RyR) are Ca(2+)-induced Ca(2+) release channels located on the endoplasmic reticulum, and consist of three isoforms, termed RyR1-3. We examined their expression in developing mouse brains by in situ hybridization. During the embryonic stage, RyR1 mRNA levels were highest in the rostral cortical plate, whereas RyR3 mRNA was most prominent in the caudal cortical plate and hippocampus. Initially, low levels of RyR2 mRNA were distributed in the diencephalon and brainstem. However, from postnatal day 7 onward, RyR2 mRNA became the major isoform in many brain regions, while RyR1 mRNA became prominent in the dentate gyrus and Purkinje cell layer. Postnatal down-regulation in the caudal cerebral cortex restricted RyR3 mRNA expression to the hippocampus, particularly the CA1 region. Therefore, RyR expression undergoes dynamic changes during the early postnatal period, when neurons are undergoing structural and functional differentiation.

Animals↗
PubMed2000

Scanning laser ophthalmoscope correlations with biomicroscopic findings and foveal function after macular hole closure.

OBJECTIVE: To investigate the relation between foveal findings and visual function in eyes with a resolved idiopathic macular hole after vitreous surgery. METHODS: We divided 28 eyes with postoperative idiopathic macular hole resolution into 3 groups based on postoperative biomicroscopic foveal findings of complete closure, partial closure, or atrophic closure. To evaluate foveal retinal function, scanning laser ophthalmoscope (SLO) microperimetry was performed preoperatively and 6 months postoperatively. RESULTS: Postoperatively in 18 eyes (64%), the foveal images became normal or almost normal and were classified as having complete closure, 6 eyes (21%) were classified as having partial closure, and 4 eyes (14%) as having atrophic closure. The corresponding visual acuity levels 6 months postoperatively were, respectively, 0.10, 0.35, and 0.64 (P<.01) based on LogMAR analysis. Preoperative SLO microperimetry detected an absolute scotoma at the bottom of all macular holes; postoperatively, the absolute scotoma disappeared in the 18 eyes with complete hole closure, but a relative scotoma was detected in 6 eyes. Of 6 eyes with partial closure, 1 had an absolute scotoma and 5 had a relative scotoma. An absolute scotoma was detected in 4 eyes with atrophic closure. CONCLUSIONS: After macular hole closure, SLO findings correlate both with biomicroscopic findings and foveal function. Better anatomical foveal recovery in eyes after macular hole closure results in better improvement of vision than in eyes in which the foveal anatomical findings are not as good.

Aged↗
PubMed2000

Changes in blood-retinal barrier permeability in form deprivation myopia in tree shrews.

To study the correlation between blood-retinal barrier (BRB) permeability and development of form deprivation (FD) myopia, FD was induced in tree shrews. The refractive error and the axial dimensions of the optical elements were measured. Ocular fluorescence was measured before and after fluorescein-Na injection. The inward permeability (P(in)) of the BRB was measured before and 15, 30, and 45 days after FD was induced. FD eyes became significantly myopic 15 days after FD was induced (P<0.01), and myopia progressed 45 days after FD was induced compared with untreated controls. Neither anterior chamber length nor lens thickness changed significantly. The vitreous chamber in FD eyes, however, was significantly elongated from 15 days after FD was induced (P<0.01) compared with controls. The P(in) ratio (P(in) [FD eye]/P(in) [untreated control]), increased significantly 45 days after FD was induced (P<0.05). In FD myopia in tree shrews, the BRB permeability increases abnormally. Impaired BRB function might be a secondary effect of myopia development rather than the cause of myopia.

Animals↗
PubMed2000

Hemorrhages of dorsal root ganglia and spinal cord in congenitally hydrocephalic HTX rat.

The effects on the brain caused by hydrocephalus have been examined in detail. However, only little attention has been paid to the possibility that hydrocephalus may affect the spinal cord and the spinal ganglia via the spinal canal. Therefore, the present study focused on the pathological changes seen in the spinal cord and the dorsal root ganglia. A total of 651 congenitally hydrocephalic HTX rats were used in this study. The age ranged from postnatal day 0 to postnatal day 520. All of the HTX rats were from littermates raised in our laboratory. Macroscopic and microscopic investigations demonstrated hemorrhages of the dorsal root ganglia in 134 rats among the 235 affected HTX rats. The hemorrhages of the dorsal root ganglia were observed most frequently in the lumbar ganglia and, less frequently, in the cervical ganglia. Of the 134 rats with hemorrhages in the dorsal root ganglia, 34 rats had hemorrhages both in the spinal cord and in the dorsal root ganglia. The spinal cord hemorrhages were distributed mainly around the central canal and in the ventral parts of the posterior funiculus at the lower thoracic and upper lumbar cords. These hemorrhages were seen only in those rats having progressive hydrocephalus. These findings suggest that increased cerebrospinal fluid pressure can cause congestion of the radicular veins, leading to hemorrhages of the spinal cord and the dorsal root ganglia.

Animals↗
PubMed2000

The cat neostriatum: relative distribution of cholinergic neurons versus serotonergic fibers.

The distribution of choline acetyltransferase (ChAT)-containing neurons and serotonin (5-HT)-containing nerve fibers in the cat neostriatum was investigated by use of immunohistochemical techniques. Both ChAT- and 5-HT-staining techniques were applied to alternate brain sections, thereby allowing a precise comparison of the distribution pattern of ChAT-immunopositive cells (ChAT cells) and 5-HT-immunopositive fibers (5-HT fibers). In the neostriatum, ChAT cells were strongly stained throughout their cell bodies and proximal (first-order) dendrites. The majority of them were multipolar cells with a soma diameter of 20-50 microm (long axis)x10-30 microm (short axis). In the caudate nucleus, ChAT cells were evenly and diffusely distributed except for the dorsolateral region of its rostral half, in which latter region they were distributed in loosely formed clusters. In the rostral portion of the putamen, the density of ChAT-cell distribution was like that in the medial region of the caudate nucleus. In contrast, this distribution was more dense in the caudomedial region of the putamen, adjacent to the globus pallidus. 5-HT fibers in the neostriatum were dark-stained, of quite fine diameter (<0.6 microm), and they contained small, round varicosities (diameter, usually 0.5-1.0 microm, but some >1.0 microm). Such 5-HT fibers were distributed abundantly throughout the caudate nucleus and putamen. In the rostrocaudal portion of the caudate nucleus, their density was high in its dorsal and ventral components, and low in the middle component. Throughout the putamen, 5-HT fibers were distributed homogeneously in the mediolateral and dorsoventral directions. In the caudal portion of the putamen adjacent to the globus pallidus, the 5-HT fibers had a higher density while maintaining their homogenous distribution pattern. In the two main divisions of the striatum, the so-called 'patch' (acetylcholinesterase (AChE)-poor) and 'matrix' (AChE-rich) compartments, there was a near-even distribution of 5-HT fibers and terminals. The above results suggest that the 5-HT-dominated, raphe-striatal pathway is optimally arranged for modulating the activity of both the intrinsic and the projection neurons of the neostriatum.

Acetylcholine↗
PubMed2000

Widespread calcium deposits, as detected using the alizarin red S technique, in the nervous system of rats treated with dimethyl mercury.

It has been reported that the alizarin red S technique may be used to visualize both intracellular and extracellular calcium deposits. Using this method histologic observations of the nervous system were made in rats that were given dimethyl mercury at 5 mg/kg per day for 12 consecutive days, and killed on days 1, 4, 7, 10, 12, 24, 32, 49, 100 and 140 (day 0 was the day that the final dose was administered). Neuronal degeneration with calcium deposition was found in the nervous system from day 4 onward. In the cerebellum alizarin red S-positive granules became gradually larger with time after dimethyl mercury administration, and large calcospherites were observed from day 32 onward. In contrast, the visualization of calcium deposits in the cerebral cortex was restricted to days 10-12. Calcium deposits were found in the ascending axons of the dorsal root ganglion neurons (dorsal fascicles of the spinal cord), but not in their perikarya. These findings suggest that widespread calcium deposition could occur in the nervous system following dimethyl mercury exposure, and that in the rat the mechanism of calcium deposition differs depending upon the brain region.

Animals↗
PubMed2000

Thiophene, a sulfur-containing heterocyclic hydrocarbon, causes widespread neuronal degeneration in rats.

Thiophene is a sulfur-containing heterocyclic hydrocarbon that has been detected in a number of environmental sources as various derivatives. Previous studies with rats have shown that thiophene induces selective degeneration of granule cells in the cerebellum, as observed with methyl mercury. To study the neurotoxicity of thiophene, Wistar rats received daily intramuscular injections of 0.2 mL thiophene for 3 days. Ataxia and convulsions were noted in all animals within 24 h after the final dose. Histologically, multiple foci of necrosis were observed in the cerebellum, predominantly in the granular layer. Neuronal damage was also found in the cerebral cortex, inferior colliculus and inferior olive. These findings suggest that thiophene causes widespread neuronal degeneration in rats and that the regional distribution of brain lesions induced by thiophene is different from that caused by methyl mercury poisoning.

Animals↗
PubMed2000

Convulsive effects of thiophene, a heterocyclic hydrocarbon: behavioral, electrographic and c-Fos immunocytochemical studies.

The behavioral, electrographic and histopathological changes induced by the heterocyclic hydrocarbon thiophene were investigated in rats following intramuscular injection of 0.3 mL thiophene for 5 days. Generalized convulsions were noted in 29 out of 34 animals (85%) between 1 and 28 h after the final dose. Electroencephalography revealed that the discharges in the hippocampus and forebrain occurred simultaneously, although epileptic activity emerged more strongly from the hippocampus than from any other region. Neuron damage was detected histologically in the temporal and parietal neocortex, piriform gyrus, amygdaloid nucleus and cerebellar cortex, but not in the hippocampus. In contrast, c-Fos was induced widely in the cerebral cortex and hippocampus, and was most marked in the dentate gyrus. These findings suggest that the hippocampus plays a crucial role in seizure onset following thiophene injection.

Animals↗
PubMed2000

[Significance of the time course of ST segment elevation just after reperfusion therapy for acute myocardial infarction].

The significance of the time course of ST segment elevation just after reperfusion therapy for acute myocardial infarction was investigated in 25 consecutive patients with acute myocardial infarction and ST elevation. The most elevated ST lead from the standard electrocardiogram on admission was continuously monitored as the ST trend for 72 hr including during the reperfusion procedure. The culprit artery was totally occluded and reperfused without flow delay. Left ventriculograms were obtained after reperfusion and 3-4 weeks later. The most elevated ST level before reperfusion was measured as the maximal level and the ST level 30 min after reperfusion as the reperfused level. The patients were divided into 2 groups, group ST > or = 50% (n = 12) with a decrease of less than 50% of the maximal ST level and group ST < 50% (n = 13) with a decrease of 50% or over 50%. Regional left ventricular wall motion of infarct site, end-diastolic left ventricular volume and ejection fraction were compared between the acute and chronic phase left ventriculograms in each group. In group ST > or = 50%, no significant change was detected in both regional and global ejection fraction, whereas end-diastolic left ventricular volume enlarged significantly in the chronic phase (acute 80 +/- 25 ml/m2 to chronic 95 +/- 17 ml/m2, p < 0.01). In group ST < 50%, regional and global ejection fraction both improved significantly (SD/chord: acute -2.2 +/- 1.5 to chronic -1.4 +/- 0.4, p < 0.001; ejection fraction: acute 50 +/- 14% to chronic 57 +/- 13%, p < 0.01) but end-diastolic left ventricular volume remained the same in the chronic phase. The peak creatine kinase level and the frequency of ST re-elevation at reperfusion were significantly higher in group ST > or = 50% than in group ST < 50% (creatine kinase: group ST > or = 50% 5,496 +/- 2,219 IU/l, group ST < 50% 1,913 +/- 1,180 IU/l, p < 0.0001; ST re-elevation: group ST > or = 50% 83%, group ST < 50% 38%, p < 0.05), although the time from onset of myocardial infarction to reperfusion, the maximal ST level, the degree of collateral development, and the frequency of pre-infarction angina were not different between the 2 groups. Rapid resolution of ST elevation after reperfusion is a useful marker of the improvement of left ventricular function in acute myocardial infarction.

Creatine Kinase↗
PubMed2000

[Comparison of the circadian variation of the time of onset of acute myocardial infarction and of attack of vasospastic angina without significant stenosis].

OBJECTIVES: To study the involvement of vasospasm as the trigger of acute myocardial infarction without significant stenosis, the circadian variation of the time of onset of acute myocardial infarction was compared with that of vasospastic angina without significant stenosis. METHODS: The subjects consisted of 3 groups, 64 patients with acute myocardial infarction without significant stenosis, 101 patients with acute myocardial infarction with one vessel disease and 98 patients with vasospastic angina without significant stenosis. The times of onset of acute myocardial infarction and spontaneous attack of vasospastic angina were recorded and classified according to the 4 periods (0:00-6:00, 6:00-12:00, 12:00-18:00, 18:00-24:00) and the pattern of distribution was compared between the 3 groups. RESULTS: The time distribution of acute myocardial infarction without significant stenosis showed a double peaked pattern at 6:00-12:00 and 18:00-24:00 and was similar to the pattern of acute myocardial infarction with one vessel disease(p = 0.93). Only a single peak in 0:00-6:00 was found in the pattern of distribution of vasospastic angina without significant stenosis and differed significantly from acute myocardial infarction(p < 0.01). CONCLUSIONS: The circadian variation of the time of onset of acute myocardial infarction was similar in patients with or without significant stenosis, and differed significantly from that in patients with vasospastic angina.

Angina Pectoris↗
PubMed2000

Endothelin-3 regulation of retinal hemodynamics in nondiabetic and diabetic rats.

PURPOSE: To investigate the mechanisms of action of endothelin (ET)-3 on the regulation of retinal hemodynamics in diabetic and nondiabetic rats. METHODS: Retinal blood flow changes were measured using video fluorescein angiography. Measurements were made before and after intravitreal injections of different ET-3 concentrations in nondiabetic rats and rats with streptozotocin (STZ)-induced diabetes. The effect of ET-3 on retinal blood flow was also investigated in nondiabetic rats after pretreatment with N:(G)-monomethyl-L-arginine (L-NMMA), a nitric oxide synthase (NOS) inhibitor; BQ-788, an ET receptor B (ETB) antagonist; and BQ-123, an ET receptor A (ETA) antagonist. Control animals were injected intravitreally with vehicle alone. RESULTS: In nondiabetic rats, ET-3 induced a dose-dependent rapid increase in retinal blood flow 2 minutes after intravitreal injection (maximal at 10(-)(8) M, P < 0. 01) followed 15 and 30 minutes after ET-3 injection by dose-dependent decreases in retinal blood flow (maximal effect at 10(-)(6) M, P < 0.05). The ET-3-stimulated retinal blood flow increase was inhibited by 10(-)(4) M BQ-788 (P < 0.01) and 10(-)(3) M L-NMMA (P < 0.05). The ET-3-stimulated decrease in retinal blood flow at later times (15 minutes) was inhibited (P < 0.03) by 10(-4) M BQ-123. In diabetic rats, baseline retinal blood flows were decreased compared with nondiabetic rats (P < 0.01), showed dose-dependent increases 2 minutes after ET-3 injection (P < 0.03), and at later times remained significantly increased (P < 0.05) in contrast to flows in nondiabetic rats. CONCLUSIONS: The ET-3-induced initial rapid retinal blood flow increase in nondiabetic rats is mediated by the ET-3/ETB and NOS action. The subsequent retinal blood flow decrease is mediated by ET-3/ETA action. Diabetic rats showed comparable ET-3-induced retinal blood flow increases indicating normal ET-3/ETB action. However, at later times, retinal blood flow remained increased, suggesting an abnormal ET-3/ETA action.

Animals↗