Biomedical subjects
Publications and source records attributed to J Naito.
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.
To examine whether left ventricular (LV) isovolumic relaxation can be assessed noninvasively using a continuous-wave Doppler technique, we compared Doppler-determined parameters derived from mitral regurgitation (MR) velocity curve with micromanometer-derived indices of LV relaxation, peak negative dP/dt and tau, in 9 patients with MR (5 with dilated cardiomyopathy, 2 with old myocardial infarction and 2 with rheumatic MR). The rate of LV pressure decay (delta P/delta t) at aortic valve closure was calculated from the recordings of MR jet velocities based on the simplified Bernoulli equation. The time constant of LV pressure decay (tD) was determined as the time from the aortic valve closure to the point where the velocity declined by (1/e)1/2. Doppler-determined delta P/delta t correlated well with hemodynamic peak negative dP/dt (r = 0.97, p < 0.001), and tD with hemodynamic tau (r = 0.89, p < 0.005). Thus, we concluded that left ventricular isovolumic relaxation can be noninvasively assessed with a continuous-wave Doppler technique in the presence of mitral regurgitation.
Inflammatory reactions were compared in the air pouch and the CMC pouch. Inflammation was induced by injection of CMC as a non-specific irritant, lipopolysaccharide (LPS) as an activator of macrophages, and methylated bovine serum albumin (m-BSA) as an inducer of delayed type hypersensitivity. There was no prominent difference in the inflammatory reactions following injection of 2% CMC solution into a 4-day-old air pouch and a 3-day-old CMC pouch. On the other hand, injection of 4 ml of 100 ng/ml LPS into each of the pouches enhanced the inflammatory reactions in the CMC pouch several-fold compared with those in the air pouch. A similar tendency was found in the case of an injection of 1 ml of 1 mg/ml m-BSA in rats sensitized with 1 mg of m-BSA. The enhanced inflammatory reactions induced by the injection of LPS or m-BSA were inhibited by dexamethasone, but not by indomethacin. These results indicate that the enhanced inflammatory reactions induced by CMC are related to lining tissue formation, which was a common characteristic in both pouches. Enhanced inflammatory reactions following injection of LPS and m-BSA were related to the activation of macrophages and newly formed blood vessels, which were not characteristic features in the air pouch, but were in the CMC pouch, in addition to the lining tissue. Cyclo-oxygenase products were not associated with the reactions.
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The fiber arrangement of the optic radiation was investigated in fourteen adult cats. The retinotopies of the lateral geniculate nucleus (LGN) were first identified electrophysiologically, and thereafter, wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was iontophoretically injected into defined positions of the LGN. These corresponded to the central (medial LGN), horizontal peripheral (lateral LGN), dorsal (rostral LGN), and ventral (caudal LGN) retina. Geniculocortical fibers from the each position of the LGN and corticogeniculate fibers projecting to these positions were always labeled reciprocally. Labeled terminals were found massively in layer IV with some extending to the lower part of layer III, but layers VI and I also contained substantial numbers. Although most of the labeled neurons were localized in layer VI, some neurons were labeled in layer V and transsynaptically in layer IV. Labeled fibers were superimposed in three-dimensionally reconstructed maps of the white matter for the easy understanding of the pathways connecting the LGN and the visual cortex. They were localized in certain zones in the white matter without wide dispersion; however, we did not obtain any findings which suggested clearly different populations of geniculocortical and corticogeniculate fibers. In agreement with previous studies, fibers from the rostral LGN and the caudal LGN projected to the striate cortex in a regular order, rostrocaudally, and fibers from the medial LGN and the lateral LGN projected to the striate cortex inversely (i.e. lateromedially). This inverse projection resulted because fibers from the lateral LGN traversed fibers from the medial LGN in a lateromedial direction; however, there was only partial crossing of these two pathways. The distribution of geniculocortical fibers together with corticogeniculate fibers formed topographic zones arrayed mediolaterally in the white matter. Thus, fibers of the medial LGN were positioned in the intermediate zone, and fibers of the rostral LGN and the lateral LGN were positioned in the rostral and caudal parts of the lateral zone, respectively. Fibers of the caudal LGN were found in the medial zone. This fiber arrangement displayed a rough centroperipheral retinotopy in that fibers representing the central area were placed between fibers representing the peripheral retina. Finally, this fiber arrangement was compared with that of the optic nerve and optic tract.
The maximum motor nerve conduction velocity of the right and left ulnar motor nerve was measured in more than 650 healthy medical students of both sexes. There was no side difference in the maximum conduction velocity. The shorter person has a statistically significant higher conduction velocity than the taller person. Comparison of students of both sexes showed a slightly higher conduction velocity in females. However, with regard to its relation to height, the conduction velocity was higher in males.
Seven Japanese monkeys (Macaca fuscata) were used to investigate the fiber pathways of the optic nerve. Optic nerve fibers and retinal ganglion cells were retrogradely labeled by iontophoretic injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into electrophysiologically defined positions of the lateral geniculate nucleus (LGN). By gross anatomical observation, the optic nerve usually had one distinct bend, which flexed dorsally 3-4 mm from the eyeball, and occasionally another ventrally directed bend was found just behind the eyeball. In the optic nerve head, fibers from the various retinal areas were arranged in a wedge according to the fiber trajectory on the retinal surface. For about a 3 mm distance from the disc, fibers rapidly spread out radially. Subsequently, rather than scattering dorsoventrally, they progressed to the chiasm with a gradual increase in the degree of mediolateral (nasotemporal) scatter. The degree of the scatter was different depending on the retinal site from which the axons originated. Fibers from the peripheral retina spread out widely for a few millimeters behind the eyeball. Thereafter the scatter was rather limited until the chiasm. On the other hand, the scatter of fibers from the foveal and parafoveal areas progressed gradually through the nerve. The present study also suggests that the difference in scatter depends on the types of cells of origin. Fibers from large ganglion cells displayed more extensive scatter than fibers from medium-sized cells. In spite of the extensive scatter of fibers, two clear segregations were found; one was a dorsoventral segregation, which was displayed by both central and peripheral retinal fibers, and the other was a center-peripheral segregation in which the fibers from the nasal central (papillomacular) retina were located almost exclusively in the central part of the optic nerve surrounded by peripheral retinal fibers. However, the temporal central retinal fibers were located in the lateral periphery of the nerve, and they overlapped significantly with fibers from the temporal peripheral retina. Furthermore, a broad intermingling was found between nasal and temporal peripheral retinal fibers owing to their mediolateral scatter. Thus, the present findings based on more precise anatomical techniques indicate that the classical notion of the retinal quadrant topography in the monkey optic nerve probably is suspect. In addition, the "rotation" of the fiber arrangement was not demonstrated.
The effects of bezafibrate on hepatic peroxisome-associated enzymes of rats, mice, guinea pigs, hamsters, rabbits, dogs and monkeys were examined. Dogs and monkeys were given bezafibrate orally at 30 mg/kg body wt daily for 2 weeks and at 125 mg/kg body wt daily for 13 weeks, respectively, and other species at 100 mg/kg daily for 2 weeks. In male rats, marked changes were observed in the activities of catalase (1.73-fold), D-amino acid oxidase (DAAO; 0.56-fold), fatty acyl-CoA oxidizing system (FAOS; 12.9-fold) and carnitine acetyltransferase (CAT; 35.8-fold); in female rats, the changes were less than in the males. In mice, there were no apparent sex differences in the responses of hepatic peroxisomal enzymes to bezafibrate and the increases in the activities of catalase, FAOS and CAT were 1.76-, 3.75- and 7.94-fold respectively. In guinea pigs, only slight increases in the activities of FAOS (3.00-fold) and CAT (2.83-fold) were observed. In hamsters, the increases in catalase, FAOS and CAT activities, were 1.23-, 2.19- and 2.77-fold respectively. Although rabbits and dogs showed slight increases in CAT activity, no significant response to the drug was observed in monkeys. Hepatomegaly and the increase of hepatic content of peroxisome proliferation-associated polypeptide (PPA-80), which has been recognized as a peroxisomal bifunctional protein in the fatty acid beta-oxidation pathway, were observed only in rats and mice. These results show that there were marked species differences in the effects of bezafibrate on hepatic peroxisomes, and that bezafibrate induced hepatic peroxisome proliferation in rodents, especially rats and mice.
We have found an enzyme system that catalyzes the conversion of L-tryptophan to L-kynurenine, presumably via L-formylkynurenine, in soluble and insoluble fractions of rat skin. The enzymatic activity was stimulated by hematin, ascorbate, and catalase, but not by methylene blue. Highest activity was located in the skin of the dorsal posterior region and lowest activity in the abdominal region. The activity in plucked (depilated) skin was only about 25% of that obtained from unplucked (depilated) tissue of the same region. D-Tryptophan, 5-hydroxytryptophan, and tryptamine were not degraded by the skin enzyme and the Km for L-tryptophan determined with the crude enzyme was 1 microM. The decycling activity of rat skin and liver for L-tryptophan began to be stimulated after birth and reached the highest level at 6 weeks. But, 1 week later, most of the skin activity suddenly disappeared and the low level continued at least until 12 weeks. In contrast, the hepatic enzyme did not change so drastically. These findings suggest that an enzyme that catalyzes L-tryptophan to L-kynurenine via L-formylkynurenine is present in rat skin.
The effect of route of administration on the induction of micronucleated polychromatic erythrocytes (MNPCEs) was examined. 6-Mercaptopurine monohydrate (6-MP) was administered intraperitoneally (i.p.) or orally (p.o.) to 2 strains of mice, MS/Ae and CD-1. From the results of an acute toxicity test and a pilot micronucleus test, the doses selected for the final micronucleus test were 12.5-100 mg/kg for the i.p. route and 25-200 mg/kg for the p.o. route. The sampling time was 48 h. Frequencies of MNPCEs increased dose-dependently by the i.p. route but peaked at 50 or 100 mg/kg for the p.o. route. 6-MP induced MNPCEs more efficiently after p.o. administration than after i.p. treatment in both strains.
In order to demonstrate the localization associated with metabolism of an anti-allergic agent, Tranilast, in the liver, light microscopic radioautography of the liver was performed. Rats were administrated orally with 3H-Tranilast, and were sacrificed at 15 minutes to 24 hours after the administration. The livers were taken out and fixed, embedded and processed for light microscopic radioautography. 3H-Tranilast was absorbed rapidly, and the radioactivity in the liver increased and decreased within several hours. The number of radioautographic silver grains reached a maximum 3 hours after the administration. From 1 to 6 hours after the administration, the silver grains decreased from the portal area toward the central area. Seventy to 80% of all silver grains on the hepatocytes were retained in the cytoplasms of the hepatocytes at any experimental period. From these results, it was concluded that the localization of radioautographic silver grains was associated with Tranilast uptake of hepatocytes in each hepatic lobular compartment and that the metabolic process from uptake to excretion of Tranilast took part in the hepatocytes in each hepatic lobular compartment.
In a carboxymethyl cellulose (CMC) air pouch inflammation model, accumulation of exudate decreased at a relatively rapid rate and almost disappeared 3 days after a 2% CMC injection into the preformed air pouch. After a second injection of 2% CMC solution into the 1-day-old CMC pouch on the day following the first CMC injection, the decrease in rate of exudate was similar to the change seen after the first CMC injection. In another group of rats, 3 days after the first CMC injection when inflammation had subsided, a second injection of 2% CMC solution into the 3-day-old CMC pouch resulted in a marked increase of exudate accumulation, inflammatory cell infiltration and vascular permeability. Histologically, large numbers of macrophages accumulated in the 3-day-old CMC pouch and fibroblast proliferation and newly formed blood vessels were also visible. The enhanced exudative reaction was significantly inhibited by dexamethasone but not by indomethacin. These results indicate that the enhanced inflammatory reactions appear to be closely correlated with the increase of reactivity at the site of inflammation and the exudative reaction was not mediated by cyclo-oxygenase products.
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For a study of the ultrastructural pathology of chondromalacia patellae, we studied biopsy specimens that had been obtained at operation in twelve young patients who had pain in the anterior aspect of the knee due to mechanical derangement and also had the pathological changes in articular cartilage that are characteristic of chondromalacia. The initial pathological finding was swelling of the superficial matrix associated with breakdown of the collagen fiber network, especially at matrix streaks in the superficial and transitional zones. Fibrillated cartilage contained surface fissures that penetrated the middle layers. Amorphous electron-dense material was found covering the internal surfaces of the fissures; this appeared to contain degraded components of the matrix. In association with these changes, there were formation of nests of cells (clusters of chondrocytes) and increased numbers of organelles in the chondrocytes. A limited repair reaction also was observed in some specimens; this was characterized by the migration of fibroblast-like cells over the surface of the cartilage. The ultrastructural observations on these specimens from patients who had chondromalacia were compatible with a pathogenesis resulting from mechanical overload.
A method for the determination of the physiological level of kynurenine in human serum based upon conversion of kynurenine to 3-hydroxykynurenine by enzymatic reaction with the mitochondrial fraction and NADPH and analysis by reversed-phase high-performance liquid chromatography with electrochemical detection is described. Tryptophan gave no interference. For one analysis, 0.2 ml of serum was sufficient, compared with the large volume (5.0 ml) required for other methods.