Biomedical subjects

J Naito

Publications and source records attributed to J Naito.

At least 73 records · Page 4Linked to original sources

PubMed1994

Retinogeniculate projection fibers in the monkey optic chiasm: a demonstration of the fiber arrangement by means of wheat germ agglutinin conjugated to horseradish peroxidase.

The fiber arrangement of the retinogeniculate pathway was investigated in the chiasm of Japanese monkeys (Macaca fuscata) by an iontophoretic injection of wheat germ agglutinin conjugated to horseradish peroxidase into the lateral geniculate nucleus (LGN). It has been claimed that there is a distinct retinotopy in the monkey chiasm, despite lack of any clear anatomical evidence. However, the present data indicate a rather gross retinotopy or almost no discernible retinotopy. Fibers from the foveal-to-peripheral axis of the temporal retina show substantially no retinotopy owing to a marked overlap of fibers in the anterolateral and the posterocentral parts of the ipsilateral hemichiasm. In contrast, the foveal-to-peripheral axis of the nasal retina is re-formed in a gross dorsoventral order in the chiasm. That is, nasal foveal-parafoveal fibers which arise from small cells (which are P beta mode) pass in the dorsal part of the chiasm adjacent to the brain. They widely overlap nasal perifoveal fibers which cross the chiasm more ventrally with very little contact with the brain. The nasal perifoveal fibers also widely overlap nasal peripheral fibers which cross the chiasm more ventrally. Furthermore, the nasal peripheral fibers overlap nasal far peripheral fibers which arise from large cells (including many of the P alpha mode) which run near the pial surface. Fibers from the dorsal and ventral nasal retina cross the midline of the posterior and anterior parts of the chiasm, respectively, and are finally positioned in the medioventral and ventrocentral parts in the tract. Consequently, the dorsoventral retinal axis is re-formed posteroanteriorly in the midline of the chiasm and in a roughly mediolateral direction in the tract. Furthermore, the present study shows that the nasal and temporal retinal fibers coming from the same eye are acutely segregated in the prechiasmal region and the anterior part of the hemichiasm.

Animals↗

PubMed1994

Inhibition by tranilast of collagen accumulation in hypersensitive granulomatous inflammation in vivo and of morphological changes and functions of fibroblasts in vitro.

We examined the effects of tranilast, an anti-allergic agent, on hypersensitive inflammation and on morphology and functions of fibroblasts. In vivo, tranilast suppressed the content of collagen in granulation tissue of hypersensitive granulomatous inflammation induced by methylated bovine serum albumin (m-BSA) in rats. In culture, tranilast inhibited the TGF-beta-independent inflammatory exudate-induced stimulation of morphological changes of fibroblasts to myofibroblast-like cells and their proliferation. Collagen gel contraction by myofibroblast-like cells and fibroblasts was also inhibited by tranilast. Flow cytometric analysis revealed that tranilast suspended the cell cycle of fibroblasts at the G0/G1 phase. These results suggest that tranilast modulates the fibrosis and contraction of granulation tissue by inhibiting the growth of myofibroblast-like cells and fibroblasts.

Administration, Oral↗

PubMed1994

Effect of successful angioplasty following thrombolysis on infarct size and left ventricular function.

The role of the angioplasty following thrombolysis in acute myocardial infarction has been discussed in several studies, however the effect of successful angioplasty on infarct size and left ventricular function has not been properly evaluated. Successful reperfusion was achieved in 79 out of 104 patients with primary anterior acute myocardial infarction. These patients were classified as follows, according to the type of intervention during the acute phase: 50 patients in which thrombolysis was successful (the thrombolysis group); 12 patients who underwent successful immediate angioplasty following successful thrombolysis (the immediate angioplasty group); and 17 patients in which rescue angioplasty was successful (the rescue angioplasty group). The 25 patients whose infarct-related vessels were not reperfused after intervention were classified as the non-reperfused group. Infarct size, evaluated as defect volume by T1-201 SPECT, 1 month after the onset, was 840 +/- 154 units (mean +/- S.D.) in the immediate angioplasty group and was similar to that in the thrombolysis group (948 +/- 88 units), but significantly smaller than in the non-reperfused group (1759 +/- 108 units). There were no significant differences in left ventricular function in the immediate angioplasty group and the thrombolysis group. Successful rescue angioplasty did not have any beneficial effect on left ventricular functions or infarct size, when compared with the failed thrombolytic group (1105 +/- 169 units vs. 1617 +/- 169 units). End-diastolic volume (52 +/- 3 ml/m2) in the successful rescue angioplasty group, however, was significantly smaller than in the failed thrombolysis group (67 +/- 3 ml/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Abnormal coronary flow dynamics at rest and during tachycardia associated with impaired left ventricular relaxation in humans: implication for tachycardia-induced myocardial ischemia.

OBJECTIVES: This study attempted to clarify the effect of ventricular relaxation abnormalities on coronary flow dynamics at rest and during tachycardia in humans. BACKGROUND: Ventricular relaxation abnormality has been demonstrated in animals to have an adverse impact on early diastolic coronary flow dynamics. However, this relation has not been established in humans. Even if the adverse effect were latent at rest, it might become evident during tachycardia because tachycardia reduces coronary flow reserve and facilitates the production of myocardial ischemia. METHODS: Doppler phasic left coronary flow velocity pattern was obtained at rest and during tachycardia in 23 patients without coronary stenosis. The time constant of left ventricular isovolumic pressure (tau) was used to assess ventricular relaxation. RESULTS: The time to peak flow velocity of the diastolic coronary flow wave was longer, and the fraction of the first third of diastolic coronary flow was smaller, in patients with a longer tau (r = 0.58, p < 0.01; r = -0.44, p < 0.05), indicating a close relation between early diastolic coronary flow dynamics and ventricular relaxation. Although rapid atrial pacing yielded an increase in the coronary flow velocity integral per minute in all patients, diastolic coronary flow velocity integral per minute increased in 9 patients with a normal (< or = 40 ms) tau at rest but decreased in 14 patients with a longer (> 40 ms) tau at rest. CONCLUSIONS: Impaired left ventricular relaxation was associated with decreased coronary flow in early diastole at rest and decreased coronary flow throughout diastole during tachycardia in patients without coronary stenosis. These findings may provide more insight into the mechanism of tachycardia-induced subendocardial ischemia in patients with impaired ventricular relaxation but without concomitant coronary stenosis.

Adult↗

PubMed1994

Analysis of transmural trend of myocardial integrated ultrasound backscatter for differentiation of hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension.

OBJECTIVES: This study was undertaken to differentiate hypertrophic cardiomyopathy from hypertensive hypertrophy using a newly developed M-mode format integrated backscatter imaging system capable of calibrating myocardial integrated backscatter with the power of Doppler signals from the blood. BACKGROUND: Myocardial integrated ultrasound backscatter changes in patients with hypertrophic cardiomyopathy; however, it is unknown whether ultrasound myocardial tissue characterization may be useful in differentiating hypertrophic cardiomyopathy from hypertensive hypertrophy. METHODS: Calibrated myocardial integrated backscatter and its transmural gradient were measured in the septum and posterior wall in 31 normal subjects, 13 patients with hypertensive hypertrophy and 22 patients with hypertrophic cardiomyopathy. The gradient in integrated backscatter was determined as the ratio of calibrated integrated backscatter in the endocardial half to that in the epicardial half of the myocardium. RESULTS: Cyclic variation of integrated backscatter was smaller and calibrated myocardial integrated backscatter higher in patients with hypertrophied hearts than in normal subjects, but there were no significant differences in either integrated backscatter measure between patients with hypertensive hypertrophy and those with hypertrophic cardiomyopathy. Transmural gradient in myocardial integrated backscatter was present only in patients with hypertrophic cardiomyopathy (5.0 +/- 1.8 dB [mean +/- SD] for the septum; 1.2 +/- 1.6 dB for the posterior wall). CONCLUSIONS: Hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension can be differentiated on the basis of quantitative analysis of the transmural gradient in integrated backscatter.

Acoustics↗

PubMed1994

Modulation of morphology, proliferation and collagen synthesis in fibroblasts by the exudate from hypersensitive granulomatous inflammation in rats.

We examined the effects of the exudate, collected from rats in which hypersensitive granulomatous inflammation was induced by methylated bovine serum albumin, on the function of inflammatory fibroblasts in culture. Addition of the exudate to the fibroblast culture induced changes in fibroblast morphology, identified by staining with antirat prolyl hydroxylase. Phase-contrast microscopy revealed that the exudate-treated fibroblasts became elongated and formed a network. Scanning electron microscopy showed that numerous long pseudopods covered the surface of the fibroblasts. Transmission electron microscopy revealed microfilament bundles with dense zones parallel to the long axis of the cell and nuclei with folds and indentations. Microfilaments were also visible in the elongated pseudopods. These features were consistent with those of myofibroblasts. The exudate also stimulated fibroblast proliferation and collagen synthesis. These findings suggest that the exudate contained certain factors that modulated fibroblast morphology, proliferation, and collagen synthesis. It is possible that putative endogenous factor(s) at the sites of inflammation modulate the development, contraction, and fibrosis of granulation tissue in hypersensitive granulomatous inflammation.

Animals↗

PubMed1994

[Age-related changes in the visual function of WBN/Kob rats--an electrophysiological study].

Changes in the visual function of the male WBN/Kob rat known as diabetic strain with increasing age were studied electrophysiologically. The measurements of electroretinogram (ERG) and visual evoked potential (VEP) in male WBN/Kob rats were performed at 5, 9, 13, 17, 23, 27, 36, 45, 54, 67 and 80 weeks of age, and compared with those in male Wistar/ST rats used as control. The prolonged latencies and decreased amplitudes of a- and b- waves and oscillatory potentials of ERG in WBN/Kob rats aged over 17 or 27 weeks were recorded under the light or after 20 min dark adaptation. The visual abnormality as indicated by non-recordable ERG was obvious in WBN/Kob rats aged 67 and 80 weeks. No changes of N1, P and N2 peak latencies of VEP were recorded in WBN/Kob rats with increasing age. The amplitudes between N1 peaks and P peaks decreased remarkably in WBN/Kob rats aged 54 weeks. The amplitudes of VEP in 67 or 80 weeks old rats in which ERG disappeared showed 26 or 28% of those in 5 weeks old rats. From these results, recording of ERG and VEP suggested that the visual abnormality occurred in male WBN/Kob rats aged 67 or 80 weeks and the process of visual abnormality with increasing age was clarified.

Aging↗

PubMed1994

Age-related changes in the visual organ of WBN/Kob rats--an ophthalmoscopical study.

Changes in the visual organ with aging were investigated non-surgically in male WBN/Kob rats, in which spontaneous diabetic mellitus commonly occurs. Male Wistar/ST rats at the ages of 5, 9, 13, 17, 23, 27, 36, 45, 54, 67 and 80 weeks were examined for changes in the peri-orbital region, eyelid, lens, corpus vitreum and ocular fundus by macroscopic inspection and fundoscopy. The area around the eyelid was stained with reddish-brown excretions from the Harderian gland. This stain was frequently observed in rats of both strains aged 54 weeks or over, showing no difference in frequency between WBN/Kob rats and Wistar/ST rats. Lens opacity was observed in male WBN/Kob rats aged 67 weeks or over, and narrowing of the retinal artery and vein in those aged 36 weeks or over. The occurrence of lens opacity was consistent with that of visual dysfunction as determined by a test of the ability to differentiate light from dark using a Y-shaped apparatus (Kiyosawa et al., 1993).

Aging↗

PubMed1994

The spinal segmental and preganglionic projections from the brainstem in relation to the chicken cloaca.

Descending projections from the brainstem to the sympathetic and parasympathetic regions of the chicken spinal cord were investigated by means of the WGA-HRP method. The segmental and preganglionic injections of WGA-HRP were made into spinal segments 20-23 and 30-33 which were sympathetically and parasympathetically related to the cloaca, respectively. After injections of a large amount of WGA-HRP into each level of segments 20-23 and 30-33, the labeled SP-neurons (segmental projection neurons) were distributed mainly in the ventral half of the medulla in both cases. The distribution of these labeled neurons extended mainly to the central (20-23 segmental injections) and the lateral (30-33 segmental injections) tegmental regions of the pons. In the mesencephalon, some SP-neurons were found in the dorsomedial reticular formation and the dorsal midline area, in addition to the Ru in both cases. By iontophoretic microinjections of WGA-HRP into the preganglionic regions of these segments, the labeled preganglionic projection neurons (PP-neurons) were found in the ventromedial part of the medulla. Both distributions of the labeled PP-neurons projecting to the sympathetic and parasympathetic regions were similar in the medulla. In the pons, although the sympathetic PP-neurons were found in the ventromedial pontine tegmentum, most of the parasympathetic PP-neurons were found in the dorsolateral tegmentum, e.g., the LoC-SC region. In the mesencephalon, a few sympathetic PP-neurons were found in the midline area ventromedial to the EW, but no parasympathetic PP-neurons were observed in the mesencephalon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Hypothalamic projections to the spinal segments and preganglionic regions by means of choleratoxin subunit B conjugated HRP in the chicken.

Hypothalamo-spinal projections were studied using the method of retrograde axonal transport of choleratoxin subunit B conjugated to horseradish peroxidase (CTb-HRP) in chickens. CTb-HRP was injected into the segmental and preganglionic regions of spinal segments 23-24 and segments 31-32 which are sympathetically and parasympathetically connected with the cloaca, respectively. Many labeled SP-neurons (segmental projection neurons) were found in the paraventricular nucleus (PVN), except in its lateral protrusion. The distribution of these labeled neurons continued to the more caudal areas such as the vicinity of the nucleus periventricularis hypothalami (PHN), areas medial to the stratum cellulare externum (SCE), the nucleus interstitialis (IS), and the posterior hypothalamic areas. Some labeled SP-neurons were also found in the lateral hypothalamic area. These labeled SP-neurons were distributed in almost the same areas in both cases of injection into segments 23-24 and 31-32. However, the number of labeled neurons was somewhat different rostrocaudally according to the spinal levels injected. In contrast, after microinjections into the spinal preganglionic regions, a small number of PP-neurons (preganglionic projection neurons) were found only in the ventral part of the PVN. These PP-neurons showed the rostrocaudally discernible segregation; PP-neurons in the rostral PVN and those in the caudal PVN were predominantly labeled by microinjections into segments 23-24 and segments 31-32, respectively. The present study suggests that the rostral PVN is more sympathetic and the caudal PVN is more parasympathetic in chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Skin L-tryptophan-2,3-dioxygenase and rat hair growth.

We have identified a new enzyme, skin L-tryptophan-2,3-dioxygenase (skin TDO), that catalyzes the degradation of L-tryptophan into formylkynurenine in rats. The rate of this degradation peaks in all rats at 5 to 6 weeks after birth, and also, among rats depilated at 8 weeks old, at 10 to 11 weeks after birth. We have also observed that the properties of this enzyme are closer to those of hepatic L-tryptophan-2,3-dioxygenase (hepatic TDO) than to indoleamine 2,3-dioxygenase. Although an intraperitoneal injection of L-tryptophan increased the activity of skin TDO to approximately 2.2 times greater than control values, an intraperitoneal injection of hydrocortisone and alpha-methyl-DL-tryptophan, both compounds known to affect hepatic TDO activity, had no effect on skin TDO activity. The molecular weight of skin TDO was estimated to be 16.0 kDa, which is close to the molecular weight of hepatic TDO, yet a much larger molecule than indoleamine-2,3-dioxygenase. Increased hair growth rates paralleled increased levels of skin TDO activity in 5- to 6-week-old rats, and marked increases in the activity of skin TDO occurred 2 or 3 weeks after depilation. Enzyme activity was also greatest 2 days before the time of maximum hair root length. Therefore, skin TDO may play an important role in the initiation or suppression of rat hair growth.

Animals↗

PubMed1993

Importance of left ventricular minimal pressure as a determinant of transmitral flow velocity pattern in the presence of left ventricular systolic dysfunction.

OBJECTIVES: This study was designed to assess whether the transmitral flow velocity pattern provides an estimation of left atrial pressure irrespective of the presence of left ventricular systolic dysfunction and, if not, to clarify the mechanism. BACKGROUND: The pulsed Doppler transmitral flow velocity pattern, particularly peak early diastolic filling velocity, has been shown to change in parallel with left atrial pressure. However, extremely elevated left atrial pressure in association with heart failure does not necessarily cause an increase in peak early diastolic filling velocity in patients. METHODS: Left atrial pressure was elevated with intravenous saline infusion in 11 dogs (normal left ventricular function group) and hemodynamic, transesophageal Doppler echocardiographic and M-mode echocardiographic variables were recorded at three different loading levels. In another 12 dogs, left atrial pressure was elevated by production of left ventricular systolic dysfunction with the stepwise injection of microspheres into the left coronary artery (left ventricular dysfunction group) and the same set of recordings was obtained at three different levels of dysfunction. RESULTS: Peak early diastolic filling velocity increased with left atrial pressure in the normal left ventricular function group and correlated with mean left atrial pressure (r = 0.61, p < 0.01) and early diastolic left atrial to left ventricular crossover pressure (r = 0.71, p < 0.01). In contrast, peak early diastolic filling velocity did not increase with left atrial pressure in the left ventricular dysfunction group and did not correlate with mean left atrial pressure (r = -0.05) or the crossover pressure (r = 0.06). Peak early diastolic filling velocity correlated well with the difference between the crossover pressure and left ventricular minimal pressure in the left ventricular dysfunction group (r = 0.64, p < 0.01). In contrast to peak early diastolic filling velocity, deceleration time of the early diastolic filling wave correlated with mean left atrial pressure and the crossover pressure irrespective of the primary cause of preload alteration (r = -0.54, r = -0.59, p < 0.01 respectively, n = 69 for all data). CONCLUSIONS: Preload dependency of the Doppler transmitral flow velocity pattern is hampered if an increase in left atrial pressure is due to left ventricular systolic dysfunction. In this setting, the increase in left ventricular minimal pressure due to left ventricular systolic dysfunction cancels the effect of the increase in left atrial pressure on the flow velocity pattern.

Animals↗

PubMed1993

Myocardial hibernation in the infarcted region cannot be assessed from the presence of stress-induced ischemia: usefulness of delayed image of exercise thallium-201 scintigraphy.

To examine the relationship between the improvement of wall motion in infarcted regions after percutaneous transluminal coronary angioplasty (PTCA) and thallium-201 uptake in the delayed image of exercise thallium-201 scintigraphy before PTCA, 14 patients with anterior old myocardial infarction were studied. Exercise thallium-201 scintigraphy was performed before PTCA of left anterior descending artery, and mean percent thallium-201 uptake of abnormal segments was calculated in the initial and 4-hour delayed images. Left ventricular angiography was performed during catheterization, before, and 4 to 13 months after PTCA; and regional ejection fraction of anterior wall was calculated. Atrial pacing stress test with the measurement of lactate concentration of aorta and great cardiac vein was performed during catheterization before PTCA. In five patients with mean percent thallium-201 uptake in the delayed image < or = 50% (group I), regional ejection fraction did not increase after PTCA (23% +/- 9% to 24% +/- 12%). In the other nine patients with mean percent thallium-201 uptake > 50% (group II), regional ejection fraction increased significantly after PTCA (39% +/- 18% to 47% +/- 14%; p < 0.05). There was no significant difference in regional ejection fraction, lactate extraction ratio during maximal pacing, and the redistribution of exercise thallium-201 scintigraphy between the two groups before PTCA. Thus the delayed image before PTCA is useful to detect reversible nonfunctioning viable myocardium (hibernating myocardium) in the infarcted region. However, the wall-motion abnormality and the degree of stress-induced ischemia in the infarcted region before PTCA may not be necessarily useful for the detection of hibernating myocardium.

Aged↗

PubMed1993

[Comparison of the gold wire electrode with cotton wick electrode for electroretinography in small laboratory animals].

Using the gold wire and cotton wick electrodes, the electroretinograms of mice and rats were measured, and then they were compared. The results obtained were as follows: 1) There were no remarkable differences in the latencies and amplitudes of a- and b-waves, amplitudes and numbers of waves of oscillatories between two different electrodes. 2) It was easy to make and maintain the gold wire electrode as compared with the cotton wick electrode. From these results, it appears that the gold wire electrode is useful for measuring the electroretinogram of small laboratory animals.

Animals↗

PubMed1993

[Possibility of detecting visual functional disturbance in rats by the open-field test].

In order to determine whether visual disturbance in small rodents is detectable by means of the open-field test, the ambulation scores of enucleated and intact rats in an open-field were measured. In a 30-min test of Slc:Wistar/ST rats, there were significant differences in ambulation scores between enucleated and intact rats in the first 10-min. In addition, the effects of observation times (09:00-11:00, 13:00-15:00 and 17:00-19:00 hr) and strains on the open-field test were studied using a 10-min test. Regardless of observation times, ambulation scores of enucleated rats of the Slc:Wistar/ST and F344/N Slc strains were significantly elevated as compared with those of intact rats from both strains. When tested during the 13:00-15:00 hr period, there were significant differences in the Slc:SD rats. These findings indicate that the changes in ambulation are due to visual disturbance. However, significant ambulatory changes in F344/N Slc rats were documented at the three different observation times. Based on these results, Slc:Wistar/ST rats appear to be suitable for detecting visual disturbance by the open-field test.

Animals↗

PubMed1993

[Visual evoked potential from dura in rats].

Visual evoked potentials (VEPs) were recorded from 8 different points (from points A and B near the bregma to points G and H near the occipital bone) of the dura under parietal bone in rats. The study was performed with 68 adult male Slc: Wistar/ST rats weighing 259.9-298.0g. VEPs recorded from the dura had a large negative component with a peak around 45 msec (N1), a large positive component with a peak around 75 msec and a large negative component with a peak around 120 msec (N2). Points A and B were not suitable for recording of the VEPs because some rats showed no N2 peak. The amplitude of peaks N1 to P at point E, upper the left optic layer of the superior colliculus, was higher than those from other points. Point E was the best position for recording of the VEP from dura in Slc: Wistar/ST rats.

Animals↗

PubMed1993

[Age-related changes in the visual function of WBN/Kob rats: a behavioral study].

Changes in visual function with increasing age were studied in male WBN/Kob rats, a new diabetic strain. In order to detect visual abnormalities in WBN/Kob rats, 5 WBN/Kob and 5 Wistar/ST (control) rats from each group were examined at 5, 9, 13, 17, 23, 27, 36, 45, 54, 67 and 80 weeks of age using dark and light distinction and open-field tests. The rates at which WBN/Kob rats selected the dark area were 85.0 to 100%, 58.8% and 52.6% at 5 to 54, 67 and 80 weeks of age, respectively, while those for Wistar/ST rats were 85.0 to 100% in each age group. Visual abnormality was obvious in WBN/Kob rats aged 67 and 80 weeks, compared with Wistar/ST rats (P < 0.05). There were no significant signs of visual abnormality in the open-field test. Detection of visual abnormality seems to be possible from 67 weeks of age.

Aging↗

PubMed1992

[The application of industrial endoscope to observation of the ocular-fundus in small laboratory animals].

Observation and recording methods of the ocular-fundus in small laboratory animals were studied using the industrial endoscope and VTR systems, respectively. The ocular-fundus was observed widely, brightly and clearly in the usual animal facility. In addition, the ocular-fundus was recorded easily and it was possible to examine the ocular-fundus recorded by the VTR systems.

Animals↗