Strain differences in the reverse tolerance to methamphetamine and changes in catecholaminergic neurons in mice

The effect of methamphetamine (MAP) on ambulatory activity and neurochemical changes in catecholaminergic neurons in the brain were investigated in dd and C57BL/6 strains of male mice. The mice were given repeatedly MAP at 2 mg/kg, s.c., 10 times at a fixed interval of 4 days. Single MAP markedly increased the ambulatory activity in both strains of mice. The ambulation-increasing effect was progressively enhanced without accompanying stereotyped behaviors when the drug was repeatedly given. The dd mice showed higher susceptibility not only to single MAP but also to the enhancing effect of the drug (reverse tolerance) that the C57BL/6 mice. On the other hand, non-treated dd mice exhibited lower maximum densities of 3H-spiperone binding sites in the striatum and 3H-WB4101 binding sites in the cortex and hippocampus than non-treated C57BL/6 mice. In contrast, the dd mice exhibited higher noradrenaline turnover than the C57BL/6 mice in the brain regions examined. The repeated administration of MAP produced decrease in the densities of both 3H-spiperone and 3H-WB4101 binding sites in the corresponding regions with increase in catecholamine turnover in dd mice. However, the similar changes were observed only in 3H-WB4101 binding sites and noradrenaline turnover in C57BL/6 mice. These results suggest that the ambulation-increasing effect of MAP is positively correlated with catecholamine turnover, while it was correlated negatively with the densities of catecholamine binding sites. Furthermore, the enhancing effect of MAP is supposed to have been partially elicited by changes in brain catecholaminergic systems, in particular an increase in catecholamine turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Complementation studies with clinical and biochemical characterizations of a new variant of multiple sulphatase deficiency

A patient with a new variant of multiple sulphatase deficiency (MSDv) is reported. Unlike the usual type, onset was late and progress was slow. The phenotypic changes were those usually seen in multiple sulphatase deficiency but much milder. Cytoplasmic accumulations were found in skin fibroblasts, and urinary mucopolysaccharides and sulphatides were high. Arylsulphatases A, B and C (ASA, B and C), heparan N-sulphatase sulphoiduronate sulphatase, and N-acetylgalactosamine 6-sulphatase all had low activity in lymphocytes and cultured skin fibroblasts. Complementation for ASA activity was found in hybrids between MSDv and metachromatic leukodystrophy (MLD) as well as between multiple sulphatase deficiency (MSD) and MLD. Complementation for ASC activity was also seen in hybrids between MSDv and X-linked ichthyosis (XLI), and between MSD and XLI. However, neither ASA nor ASC activity increased in hybrid cells of MSDv and MSD. These results suggested that the mutations of MSDv and of MSD were allelic, although of different phenotypes.

Age-related morphological changes in auditory middle-latency response

Age-related changes in the waveforms of the middle latency response (MLR) were investigated in 9 adults and 28 children aged between 4 and 14 years. The children were classified into three groups according to their age. For obtaining characteristic configurations in the responses for each group, composite group averaging was performed by summating the individual recordings in each group. With high-pass digital filtering at 20 Hz, composite MLR for adults showed a well-defined Na-Pa-Nb-Pb complex with peak latencies at about 17, 30, 45 and 63 ms, respectively. The composite response for children aged 4-7 years was characterized by a broad positive deflection (Pa) followed by a negative peak (Nb) at about 40 and 60 ms after stimulus onset, respectively. The peak latency of Pa was close to the adult value in the composite MLR for subjects aged 8-11 years, while the complete adult pattern in the later part of the response was not reached even in the composite response for subjects aged 12-14 years.

[Development of reverse tolerance to the ambulation-increasing effect of ephedrine after repeated administration in mice]

Effects of repeated administration of ephedrine (EPH) 40 and 80 mg/kg sc, and 20, 40, and 80 mg/kg ip on ambulatory activity in adult male mice of the dd strain were investigated. The drug was administered 5 times at intervals of 1 and 7 days. The ambulatory activity of each mouse was measured by a tilting-type round activity cage of 25 cm in diameter for 150-210 min after the drug administration. Repeated administration of EPH 80 mg/kg ip produced a marked augmentation in the sensitivity of the mouse, i.e. reverse tolerance, to the ambulation-increasing effect of the drug regardless of the administration intervals. However, repeated administration of 80 mg/kg sc and 40 mg/kg ip at intervals of 7 days caused a slight reverse tolerance, while 40 mg/kg sc at intervals of 7 days as well as 20 and 40 mg/kg ip at intervals of 1 day did not produce reverse tolerance. In contrast, a poorer development of reverse tolerance to the ambulation-increasing effect of EPH was observed when a mouse was confined in a glass jar of 5 cm in diameter to impede ambulation for 150-180 min after each administration. Mice showing reverse tolerance to EPH demonstrated an increased sensitivity to methamphetamine as compared with the saline-pretreated control mice. The present results suggest that the characteristics of reverse tolerance to ambulation-increasing effect of EPH are almost identical with those after methamphetamine and methylphenidate.

Auditory brainstem response (ABR) to tone pips in hearing-impaired children

The correspondence between ABR thresholds to tone pips and behavioral thresholds at 500, 1000 and 2000 Hz was studied in 13 normal and 55 hearing-impaired children, including 42 sensori-neural losses and 13 conductive losses. The children's ages ranged from 1 year 3 months to 8 years. Tone pips were provided with 2-cycle rise-fall times and 2-cycle plateaus. The correlations between the two measures were highly significant at 3 frequencies both in sensori-neural losses and conductive losses. In the subjects with sensori-neural losses, the ABR thresholds tended to be lower than the behavioral thresholds. Mean threshold differences between the ABR and behavioral audiometry at each frequency in sensori-neural losses were 1.6, 0.26 and 5.8 dB, respectively. On the other hand, in the subjects with conductive losses, the ABR thresholds were higher than the behavioral ones by 9.6, 7.8 and 7.5 dB at respective frequencies. Therefore, the hearing acuity in young children with sensori-neural losses can be predicted with accuracy from the ABR thresholds to tone-pips at 500, 1000 and 2000 Hz.

Effects of analog and digital filtering on auditory middle latency responses in adults and young children

Effects of analog high pass (HP) filtering were compared with those of zero phase-shift digital filtering on the auditory middle latency responses (MLR) from nine adults and 16 young children with normal hearing. Analog HP filtering exerted several prominent effects on the MLR waveforms in both adults and young children, such as suppression of Po (ABR), enhancement of Nb, enhancement or emergence of Pb, and latency decrements for Pa and the later components. Analog HP filtering at 20 Hz produced more pronounced waveform distortions in the responses from young children than from adults. Much greater latency decrements for Pa and Nb were observed for young children than for adults in the analog HP-filtered responses at 20 Hz. A large positive peak (Pb) emerged at about 65 ms after the stimulus onset. From these results, the use of digital HP filtering at 20 Hz is strongly recommended for obtaining unbiased and stable MLR in young children.

An electron-microscopic study of the endothelium in mammalian bronchial microvasculature

The endothelial ultrastructure and permeability in sequential segments of the bronchial microvasculature of the rat, guinea pig, and hamster, were examined electron-microscopically before and after perfusion with horseradish peroxidase (HRP) or tannic acid. Transendothelial channels are common in the bronchial venules of all three species. Fenestrated capillaries are present just beneath the bronchial epithelium. The endothelial fenestrae, transendothelial channels, and leaky endothelial junctions in venules are permeable to tracers such as HRP and tannic acid, indicating that the microvasculature of the bronchial circulation may be more permeable than that of the pulmonary circulation.

[Characteristics of reverse tolerance to ambulation-increasing effect of methylphenidate after repeated administration in mice]

Effects of repeated administration of methylphenidate (MPD) 2, 4, 8 and 16 mg/kg, sc on ambulatory activity in adult male mice of old strain were studied. The ambulatory activity of each mouse was measured by a tilting-type activity cage for 90-150 min after the drug administration. The repeated administration of MPD 2 and 4 mg/kg at intervals of 3-4 days, and 4 mg/kg at intervals of 7 days produced an augmentation in the sensitivity of the mice, i.e., a reverse tolerance, to the ambulation-increasing effect of the drug. However, the repeated administration of MPD 4 mg/kg at intervals of 1 day, and 8 and 16 mg/kg at intervals of 3-4 days did not produce the reverse tolerance to it. The mice repeatedly given 16 mg/kg at intervals of 3-4 days exhibited an augmentation in stereotyped behaviors. The reverse tolerance, once produced, was well maintained 45 days after cessation of the repeated administration. Only a little reverse tolerance to MPD was produced in the mice repeatedly given the drug in their home cage, in which the mice were group-housed, and the extent was significantly less than that observed in the mice given the drug in the activity cage. In addition, the mice showing the reverse tolerance to MPD demonstrated an increase in sensitivity to methamphetamine as compared with the saline-given control mice. The present results suggest that the characteristics of reverse tolerance to the ambulation-increasing effect of MPD is almost identical with that after methamphetamine.

[Development and characteristics of reverse tolerance to repeatedly administered morphine in mice manifested by enhanced motor activities]

Characteristics of changes in ambulatory activity after repeated administration of morphine, 5, 10 or 20 mg/kg s.c., were investigated in male mice of dd strain. The drug was administered 10 times at intervals of 1, 3-4 or 7 days, and the ambulatory activity of each mouse was measured by a tilting-type round activity cage with a 25 cm diameter for 180 min after each administration. Morphine, 5-20 mg/kg induced a dose-dependent increase in the ambulatory activity, and this effect attained to a peak at 60-90 min and persisted for 120-180 min after the administration. An augmentation of sensitivity (a reverse tolerance) to the ambulation-increasing effect of morphine was induced by the repeated administration of 10 and 20 mg/kg morphine, regardless of the intervals. The reverse tolerance achieved the maximum on the 5-6th administration day, and almost the same level of sensitivity was maintained until the 10th administration day. There was no significant difference in the activity counts at the peak time among the groups of mice varying the administration intervals. However, the persistence of increased ambulatory activity tended to be longer in the group of mice given morphine at intervals of 7 days than in the group given it at intervals of 1 day. The reverse tolerance, once produced, attenuated 2 months after the cessation of the repeated administration. However, the ambulatory activity counts did not return to those on the 1st administration day.(ABSTRACT TRUNCATED AT 250 WORDS)

Double hexagonal superstructure of Au–Mg alloy containing 20 at.% Mg studied by high-voltage high-resolution electron microscopy

High-resolution observations of Au–20.2 at.% Mg alloy have been carried out by using a 1 MV electron microscope. The many-beam images with the [001] axial illumination are interpreted in terms of the double hexagonal superstructure of 9a 0−4H type. With the aid of computer simulations by the multislice method, it is revealed that two kinds of interpretable image are obtained for different specimen thicknesses at the optimum defocus. The imaging conditions are discussed in comparison with the orthorhombic structure of the D023 type.

Frequency composition of auditory middle responses

Power spectral analysis and digital filtration were performed on the auditory middle responses (AMR) to click stimuli in six subjects with normal hearing. The spectral analysis revealed that the main power of the AMR was located at frequencies between 30 and 50 Hz with a peak at 40 Hz. A small elevation of power observed in the spectrum between 90 and 180 Hz was considered to be due to the ABR and the earliest part of the AMR. Typical AMR components, namely Na, Pa, Nb and Pb, were constantly recognised with digital high-pass (HP) filtration at 30 Hz. With increasing cut-off frequencies up to 50 Hz, the peak latencies of Na and Pa remained unchanged, while their magnitudes markedly decreased. On the other hand, Pb completely disappeared with 40 Hz filtration, forming two distinct positive peaks at about 55 and 80 ms after the stimulus onset. In some cases, three small positive peaks were seen following Pa with HP filtration at 50 Hz. With 60 Hz HP filtration, main components of the AMR substantially disappeared.

Auditory middle responses in young children

In order to ascertain if any substantial difference exists in the auditory middle responses (AMR) between adults and young children, a digital high-pass (HP) filtering technique was applied to the responses in 26 young children aged 1-7 years and nine adults with normal hearing. Two significant differences were found between the HP-filtered responses in children and those in adults. Pa in the responses from adults was consistently recognized with HP filtering up to 50 Hz, while Pa in young children was effectively detected only with 20 Hz HP filtering. It was mostly eliminated when the HP filter was set at 30 or 40 Hz. Pb was identified in most of the adult responses, particularly with HP filtering at 30 Hz. On the other hand, it was not visually distinguished in the responses from young children with any HP filter setting.

A study of the ordered structures of the Au–Mn system by high-voltage–high-resolution electron microscopy. II. Two-dimensional antiphase structures based on the DO 22 structure

Two-dimensional antiphase domain structures existing in the composition range 20–23 at.% Mn were investigated by a high-resolution structure-imaging technique with a 1 MV electron microscope. The structures are based on the DO 22 structure and consist of parallelogram-shaped domains containing 4 × 3 columns of Mn atoms and lozenge-shaped domains with 4 × 4 and 3 × 3 columns, and the domains are separated by two-dimensional antiphase boundaries parallel to the ({\bar 2}40) and (240) planes of the fundamental face-centred structure. The configuration of the domains changes delicately with a slight change of composition or annealing temperature, and the symmetry of the structure is lowered below about 670 K. The ideal structure models have compositions of about 22.7 at.% Mn. The images of about half of the specimen area of the 22.6 at.% Mn alloy annealed at 570 K do not correspond to these new structures, but bear a resemblance to the image expected from the two-dimensional antiphase structure proposed by Watanabe [J. Phys. Soc. Jpn (1960), 15, 1030–1040] for Au3Mn, which is based on the L12 structure and has boundaries parallel to the (100) and (010) planes.

Enhancing effect of methamphetamine on ambulatory activity produced by repeated administration in mice

Effect of repeated administration of methamphetamine (MAM) on ambulatory activity was studied under various experimental conditions. Nine groups of mice received 10 doses of 1, 2 or 4 mg/kg MAM on a daily, 3-4 day or weekly schedule. Increases in activity were enhanced progressively in proportion to the number of MAM doses, but the extent varied with the dose and interval of repetition. One mg/kg caused slight enhancement under all conditions. In the case of 2 mg/kg, marked enhancement was observed until the 7th-8th administration in 3-7 day schedules, but poorer enhancement was elicited by daily administration. Four mg/kg of daily repetition caused no enhancement, because of marked stereotyped behavior which competed with ambulation. However, the enhancement was observed in the 3-7 day schedule when stereotyped behavior was not prominent. The enhancement was well maintained after a 2 months drug-free period. When a mouse was confined in a jar of small diameter to impede ambulation after MAM, the enhancement was blocked. These results suggest a possibility that learning of drug effect in association with environmental factors may play an important role in the enhancing effect.

Single crystal alumina for dental implants and bone screws

When ground to a suitable form, flexural strength of single crystal alumina (Al2O3) decreases to as low as one third the strength of the intact crystal. This flexural strength decrease is, however, recovered by chemical etching at a high temperature to eliminate surface defects caused by grinding. By using this strength recovery treatment, various types of single crystal implants with fine structure were able to be designed. Four kinds of single crystal bone screws and single crystal dental implants of screw and anchor type were designed. Flexural strength and impact strength of the implants were measured.

[Individual differences in the accelerating effect of methamphetamine, d-amphetamine and morphine on ambulatory activity in mice (author's transl)]

Several problems concerning the ambulatory activity were discussed from the viewpoint of drug assay using about 700 adult male mice of ddG strain. Each response pattern for 180 approximately 400 min obtained from the temporal changes of ambulatory activity after administration of methamphetamine (1 approximately 16 mg/kg s.c.), d-amphetamine (1.25 approximately 5 mg/kg s.c.) or morphine (5 approximately 20 mg/kg s.c.) was recorded and used for the data analysis. All the above mentioned drugs markedly accelerated the activity when the doses were optimal. However, the individual response to the drugs sometimes reached a 40- approximately 70-fold difference, even though both animal and measurement conditions were fixed as constant way as possible. The time when the experiments took place did not explain the individual differences, nor did the season or body weight of the animal. However, there was the possibility of colony differences. Animals with relatively high activity prior to drug administration tended to respond more forcibly after administration of the drugs. It was found from the statistical investigation that constant observation of over 1 hr using at least 15 animals was required in order to determine a standard effect of the drug. Furthermore, the accelerating effect of methamphetamine and d-amphetamine on the activity was observed to be dose-dependent when below 4 and 5 mg/kg was given, respectively. On the contrary, the effect decreased dose-dependently when higher doses were given as stereotyped behavior such as head-swaying, continuous sniffing and circular movements in opposition to the horizontal movements also developed dose-dependently. As the qualitatively different behavior could be simultaneously measured, the individual differences were more apparent.

[Simple and easy method for measurement of ambulatory activity in mice (author's transl)]

A hand-made apparatus which is easily manipulative, cheap, durable and clean was used to measure ambulatory activity of a mouse. The apparatus was assembled with the same type of two plastic round basins commercially available (25 cm in diameter) put one upon another. A pivot was fixed at the center of the outsurface of the inner basin (A), and its open end was inserted into the open socket fixed at the center on the bottom of the outer basin (B). Three microswitches equipped on the brim of (B) at equal intervals were activated and the counts were recorded according to the tiltings of (A) through the movements of the mouse. In order to examine accuracy of the measurement, effects of d-amphetamine (1.25 approximately 5.0 mg/kg), methamphetamine (1.0 approximately 4.0 mg/kg), cocaine (10 approximately 40 mg/kg) and morphine (5.0 approximately 20.0 mg/kg) on the ambulatory activity were investigated. Marked accelerating effects were observed dose dependently after the administrations of all the drugs. Furthermore, the patterns of the activity showed characteristic properties of each drug. This method is especially useful to measure the acute effect of drugs on the ambulatory activity in mice, and many units can be set up at the same time.