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Biomedical subjects

H Aikawa

Publications and source records attributed to H Aikawa.

At least 91 records · Page 5Linked to original sources
PubMed1988

Shaking rat Kawasaki (SRK): a new neurological mutant rat in the Wistar strain.

Shaking rat Kawasaki (SRK), a newly discovered neurological mutant rat in the Wistar strain, is described. The abnormalities of SRK rats are transmitted as an autosomal recessive trait. The neurological signs are shaking of the body and an ataxic-paretic gait from day 10 postnatal. The affected rats survive for about 1 month. Macroscopically, the cerebellum is small and frequently the vermis and paraflocculus lacking. The most conspicuous histological finding in the central nervous system is malposition of the neurons in the cerebral cortex, hippocampus and cerebellum. Myelination and synapse formation are intact. Abnormal myelinated fibers are present in the molecular layer of the cerebral cortex and in the central gray matter of the spinal cord. These morphological abnormalities resemble those reported in the reeler mutant mouse. SRK rats are another good animal model of human congenital malformations with neuronal migration disorders.

Animals↗
PubMed1988

[Changes in blood toluene concentrations in rats under various kinds of exposure conditions and physical loads].

The present experiment was conducted under the assumption that exposure conditions (time of exposure, concentration of exposed substances and working intensity) should be taken into account in estimating the level of invasion of injurious substances into the human body. Experiments were carried out on rats under various exposure conditions of toluene and the toluene concentration in the blood was monitored for the estimation of its intake. The results were as follows; 1. It was confirmed that toluene concentration in blood increased and plateau-time was delayed in proportion to increase in exposure concentration. 2. Light exercise (5.0, 7.0 m/min) increased toluene concentration in blood and it was proportioned to intensity of physical exercise. 3. Light daily exercise (2.7 m/min) for six days increased toluene concentration in blood gradually day after day when compared to exposure without exercise, though the exposure conditions were the same every day. It is thus considered that physical exercise is one of the very important factors in estimation of exposure.

Animals↗
PubMed1988

Urinary hippuric acid excretion in everyday life.

The biological monitoring for exposure to toluene is based on the measurement of urinary hippuric acid concentration (HA-U). In occupational health, workers exposed to toluene are examined for HA-U, because collection of urine samples is easy. The HA-U of some designers in a great household electrical products corporation who did not use toluene occupationally showed relatively high values. From statistical analyses, it was revealed that the HA-U values of the designers who lived without family members were higher than those with family members and that the values on Monday were higher than those on Friday. Some factors which elevate the HA-U level are considered in individuals living alone and/or in life at weekends. These may be to drink many soft drinks, especially low calorie ones, in which benzoic acid is used as a preservative.

Adult↗
PubMed1987

Experimental chronic subdural hematoma in mice. Gross morphology and light microscopic observations.

A new experimental model of chronic subdural hematoma in mice is described. A single intraperitoneal injection of 6-aminonicotinamide (25 mg/kg body weight) on the 5th postnatal day induced hydrocephalus in mice with almost 100% success. Approximately 60% of the mice spontaneously developed intracranial hemorrhage 20 days after the injection. About 1 week after the hemorrhage, a lens-shaped or spherical subdural hematoma was observed, accompanied by marked dilatation of the lateral ventricles and intraventricular hemorrhage. Histological examination revealed that the hematoma contained well-organized outer and inner membranes. Fresh hemorrhage surrounded by many hemosiderin-laden macrophages was seen at the margin of the hematoma adjacent to the organizing outer membrane, in which many fibroblasts and blood vessels were noted. The inner membrane of the hematoma was made up of several tiers of flattened cells with thin-walled blood vessels. The gross morphology and histology of these hematomas closely resembled those of human chronic subdural hematoma.

6-Aminonicotinamide↗
PubMed1987

[Digital subtraction angiography of the coronary artery: evaluation of morphological aspects].

The usefulness of digital subtraction angiography (DSA) in coronary angiography was evaluated in terms of its ability to delineate the coronary artery and aortocoronary (A-C) bypass grafts. First, 59 intra-arterial injections of contrast media were made for 23 patients with ischemic heart disease. With aortic root injection, the proximal coronary artery was moderately well visualized, but visualization of the peripheral arteries was inadequate. By selective coronary injection, good images of the coronary arteries were obtained using small quantity of contrast media; however, detailed evaluations of the degrees of stenosis and collateral circulation were difficult, because of limitations in spatial resolution and misregistration artifacts due to cardiac pulsations. In addition, the patencies of 12 A-C bypass grafts were evaluated using intravenous (IV-) DSA for three cases and intraaortic (IA-) DSA for five cases. Ten grafts were shown to be patent. With IV-DSA, the graft was imaged as superimposed on the ascending aorta. In IA-DSA, a small (4F) catheter was introduced via the right brachial artery and advanced to the ascending aorta where an aortic root injection was performed. With aortic root injection, not only the anastomotic portion but also the distal native coronary artery were visualized. Lateral and severe left anterior oblique projections were best to visualize the grafts. IA-DSA using 4F catheter could be performed for outpatients without complications. The patency of a graft can be evaluated with the time density curve between two points in the graft, and the coronary blood flow can be calculated using the time density curve measurements and the diameter of the artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1987

Urinary hippuric acid excretion after use of spray ski-wax and remover.

The biological monitoring for exposure to toluene is based on the measurement of urinary hippuric acid concentration (HA-U). In occupational health, workers exposed to toluene are examined for HA-U, because collection of urine samples is easy. The HA-U data of an engineer who did not use toluene occupationally showed relatively high values. It was indicated that he went to ski every weekend in winter and had used spray ski-wax and remover which contained toluene. The ski-club members of Tokai University, School of Medicine who used such sprays were examined for HA-U at the ski training camp. It was revealed that the use of these sprays elevated the HA-U values remarkably. Therefore, the use of sprays, especially in the winter season, can be one of confounding factors for biological monitoring of occupational exposure to toluene based on measurement of HA-U.

Adult↗
PubMed1986

Aqueductal lesions in 6-aminonicotinamide-treated suckling mice.

Suckling mice which received a single intraperitoneal injection of 6-aminonicotinamide on the 5th postnatal day, consistently developed hydrocephalus. During the early stages of hydrocephalus (7-9 days after injection), aqueductal lesions were characterized by edematous ependymal and subependymal cells, and spongy changes in the periaqueductal area, which resulted in aqueduct stenosis. Later stages (after 20 days post-injection) showed that these edematous changes totally subsided, leaving an obliterated aqueduct which was similar to that of human congenital hydrocephalus. At the completely obliterated area, ultrastructural investigation disclosed a normal-looking neuropil but no aqueductal lumen. In the remaining ependymal cell, increased intermediate filaments and lipid droplets occurred. These data suggest that acute ependymal cell degeneration during the perinatal period may result in the profile of aqueduct "agenesis" in human congenital hydrocephalus.

6-Aminonicotinamide↗
PubMed1986

Ultrastructural evidence of mitotic ependymal cells in 6-aminonicotinamide-treated suckling mice.

Mitotic ependymal cells were encountered in 10-day-old mice treated with 6-aminonicotinamide, an antagonist of niacin. These occurred along the medial surface of the lateral ventricle and the ventral portion of the aqueduct. Electron microscopy revealed that both mitotic ependymal cells had eccentrically placed chromosomes without a nuclear membrane and well-formed gap junctions in contact with adjacent ependymal cells. Microtubules from a centriole radiated to the chromosomes. These data show that cell division occurs in morphologically matured ependymal cells in the postnatal brain under pathological conditions. We believe this to be the first ultrastructural demonstration of this phenomenon.

6-Aminonicotinamide↗
PubMed1986

Postnatal mitotic division of endothelial cells in the brain.

Ultrastructural details of capillary endothelial cells undergoing mitosis in the central nervous system are reported. These mitotic endothelial cells were seen in the brain of 10-day-old mice treated with 6-aminonicotinamide, an antagonist of niacin. Electron microscopy revealed these cells to be characterized by segregated chromosomal materials and the absence of a nuclear membrane. They possessed well-formed tight junctions with adjacent endothelial cells. Numerous microtubules radiated from a centriole toward the chromosomal material. The basal lamina of these dividing endothelial cells was not always well defined and, in some portions was discontinuous. We believe this to be the first ultrastructural demonstration of mitotic endothelial cells in the postnatal brain.

Animals↗
PubMed1986

[Effects of peri- and postnatal lead administration on learning of high avoider rats].

Effects of administration of lead acetate on Sidman avoidance behavior were assessed in juvenile and adult rats which were obtained by continued selective breeding and which have a high level avoidance ability and small individual differences (THA rat: Tokai high avoider rat). THA rats were administered lead acetate solution at 200-300 mg/kg/day as Pb until 7 wk of age through maternal milk before weaning from mothers which had been administered lead acetate from the 13th day of gestation and per os by gastric tube after weaning. Three series of Sidman avoidance behavior tests were conducted from 49th, 100th and 150th day after birth each for 10 d, 1 h every day. In the first series, a significant delay of shock avoidance acquisition was observed in lead-administered male rats compared with the control subjects, while no acquisition delay was seen in female rats. The lead administered male rats could be divided into two groups with different response patterns; a low susceptible group (LSG) which exhibited as good acquisition rate from the beginning similar to the control rats and a high susceptible group (HSG) which showed a significant delay and individual differences. In the 2nd test series, very high avoidance rates were obtained in all the test groups except in male HSG, but in the 3rd test series, male HSG also attained a final acquisition of high avoidance rate. There was no developmental variation between the groups nor difference in lead contents of the organs of the exposed group. Useful characteristics of THA rats for behavioral toxicology are discussed.

Animals↗
PubMed1986

[Effects of low level toluene exposure during the developing stage of the brain on learning in high avoider rats].

THA (Tokai High Avoiders) rats were exposed in the exposure chambers to 100 and 500 ppm of toluene and air for 7 h every day from 13th day of gestation to 48 d of age. After the termination of toluene exposure, Sidman avoidance test was conducted on the rats for 10 d from 49 d of age (first test series), 100 d of age (second test series) and 150 d of age (third test series). The results obtained are as follows. No difference could be observed between the toluene exposed groups and controls in the initiation of pinna detachment, primary coat of downy hair, incisor eruption and eye opening. The body weight of the 100 ppm exposed group was slightly greater than that of the control and the 500 ppm exposed group. No difference was indicated between these three groups in reflex and locomotor activity. Avoidance learning: Avoidance rate in the two exposed groups of male rats was significantly lower than those in the control during the 60 min of the test in the first test series. The magnitude of individual variations of avoidance rate in the two exposed groups of male rats was also remarkably greater than that of the control. No difference was seen between the two exposed groups in both avoidance rate and magnitude of avoidance variation. In the second and third test series, the avoidance rate of the two exposed groups still did not attain the control levels during the period of the test series. In female rats, the avoidance rate of the two exposed groups during the first 30 min of the test in the first test series was slightly lower than the control. This difference in avoidance rate observed between the exposed groups and the control disappeared during the latter 30 min of the test. In the second and third test series, the avoidance rate of both exposed groups reached the control level during the test period. It may be concluded from the foregoing findings that 100 ppm and 500 ppm toluene exposure during the fetal and suckling periods affects learning in the rats after termination of the growth period, and that the learning disorder still remained as long as 100 days after the end of toluene exposure, although the effect decreased gradually. It was also observed that this learning disorder appeared more distinctly in male rats than in female rats.

Animals↗