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Notes: Abstract Deciduous teeth affected by dentinogenesis imperfecta were obtained from two patients with osteogenesis imperfecta. Electronmicroscopy of the dentin revealed some structural alterations. The striation of the collagen fibrils was not clear, and the crystals were less dense than in normal dentin. The amino acid analysis of dentin collagen was slightly different from normal dentin. There were slight increases in the amounts of hydroxylysine. serine and acidic acids. On the other hand, lysine and arginine were reduced. The elevation of hexosyllysine content and an increase of carbohydrate were also observed.These results indicate that either dentin collagen is altered, or noncollagenous matrices associated with collagen are increased in dentinogenesis imperfecta dentin.

Notes: Based on accurate X-ray diffraction intensity data collected from spherically shaped single crystals, net atomic charges and electron density distributions have been studied for MnO, Mn2SiO4, Mg2Si2O6, LiAlSi2O6 and CaMgSi2O6. Examination of various procedures for determining atomic charges in a given structure has led to the conclusion that the following approach appears to be most reliable. (1) For cations: the number of electrons in the sphere of radius ER, effective distribution radius, which is defined according to the characteristics of radial distribution functions or difference-Fourier maps, is calculated. (2) For oxygen atoms: with the cation charges fixed at the values obtained from the above procedure and the total charge of the crystal constrained to be neutral, oxygen charges are estimated from least-squares refinements using atomic scattering factors. The final charges of atoms examined are less ionic than the corresponding formal ones: those of Li, O, Mg, Al, Si, Ca and Mn are respectively + 0.7 (1), -1.1 to -1.5, + 1.4 (1) to + 1.8, + 2.4(1), + 2.2 (1) to + 2.6, + 1.4 (2) and + 1.2 (1) to + 1.6 e. Residual electron densities between Si and O have been clearly observed in difference-Fourier maps after charge refinements for crystals of LiAlSi2O6, CaMgSi2O6 and Mg2Si2O6.

Notes: A white (defect) line which appears as a dip in intensity distribution was clearly observed in the 200 diffuse scattering from a Cu-Al disordered crystal at room temperature in the Bragg geometry by using both photographic and counter methods. The line is caused by the extinction effect on the 200 Bragg reflection, subsequent to the diffuse scattering, in a process similar to the case of mosaic crystals. The diffuse scattering is caused by the static displacement as well as the thermal motion of atoms. The observed contrast of the line is quantitatively in fair agreement with that calculated.

Notes: Summary An autopsy case of human T lymphotropic virus I-associated myelopathy (HAM) of a duration of 28 years in a 61-year-old man with serological confirmation of HTLV-I infection was reported. The spinal cord was grossly atrophic. There was severe symmetrical degeneration of the lateral funiculi, particularly of the bilateral pyramidal tracts, involving all levels of the spinal cord, but anterior horn cells were relatively well preserved. In the most severely damaged middle and lower thoracic segments, the white matter degeneration also involved the anterior funiculi. In the degenerated white matter, both the myelin and axons were equally lost and had been replaced by glial scars. Marked adventitial fibrosis was commonly seen in small parenchymal vessls in both the white and gray matter. Although there was no evidence of inflammation in the spinal cord, mild lymphocytic infiltration was occasionally observed in the subarachnoid and perivascular spaces in the brain stem, cerebellum and cerebrum. This case was considered as a burnt-out case of HAM.

Notes: Summary 1. Projections of reticulospinal neurones (RSNs) in the nucleus reticularis pontis caudalis (N.r.p.c.) to dorsal neck motoneurones supplying splenius (SPL, lateral head flexor) and biventer cervicis and complexus (BCC, head elevator) muscles were studied in the cat anaesthetized with pentobarbiturate or α-chloralose. 2. Threshold mapping for evoking antidromic spikes revealed that most of RSNs tested projecting down to brachial segments but not to lumbar segments (C-RSNs) gave off collaterals to the gray matter of the upper spinal cord in C2–C3 segments. 3. Spike triggered averaging showed that negative field potentials were evoked after firing of a single C-RSN (single fibre focal synaptic potentials, FSPs) in the region of C2–C3 where large antidromic field potentials from nerves supplying SPL or BCC muscles were evoked. The single fibre FSPs ranged between 1 and 10 μV in amplitude and had latencies between 0.7 and 1.2 ms from the onset of the triggering spike. In most cases, a presynaptic spike preceded the negative potential by 0.3 ms. These results indicated that C-RSNs project to the SPL or BCC motor nucleus. 4. Spike triggered averaging of postsynaptic potentials revealed EPSPs (single fibre EPSPs) in 36 dorsal neck motoneurones, predominantly in SPL (25) and less in BCC (11) motoneurones, evoked from 15 C-RSNs. The amplitude of the single fibre EPSPs ranged from 5 to 310 μV, and had latencies of 0.8–2.0 ms from the onset of the triggering spikes of C-RSNs, or 0.3–0.5 ms from the presynaptic spike when recorded. The results indicated monosynaptic excitatory connexions of C-RSNs to dorsal neck motoneurones. 5. Single fibre EPSPs from a C-RSN were usually recorded from either BCC or SPL motoneurones but not from both types of motoneurones, when tested in many motoneurones. This showed that connexions of C-RSNs with dorsal neck motoneurones were muscle specific. 6. RSNs projecting down to the lumbar segment (L-RSN) also showed branching in C2–C3 segments. Excitatory monosynaptic connexion of L-RSNs with neck motoneurones were demonstrated by recording single fibre postsynaptic population potentials (p.s.p.p.s.) from the C2 ventral root perfused with sucrose. The probability of evoking monosynaptic single fibre p.s.p.p.s. was less (19%) than for C-RSNs (59%).

Notes: Summary Dorsal neck motoneurones receive disynaptic tectal and pyramidal EPSPs via common reticulospinal neurones (RSNs). This study was aimed at identification of the RSNs projecting directly to neck motoneurones and mediating these EPSPs. 1. Stimulation of the tectum and the cerebral peduncle evoked monosynaptic descending volleys in the spinal cord, which were chiefly mediated by reticulospinal neurones in the pons and the medulla. Systematic tracking of the C3 and C7 segments was made to locate descending volleys in the spinal funiculi. The tectal monosynaptic volley was largest in the medial part of the ventral funiculus and decreased gradually as the recording electrode was moved to the lateral part of the ventral funiculus and the lateral funiculus. In contrast, the peduncle-evoked monosynaptic volley was distributed rather evenly in the ventral funiculus and the ventral half of the lateral funiculus. 2. Differences in funicular distribution of the two descending volleys suggest the existence of subgroups of RSNs which differed in strength of inputs from the two descending fibre systems and in the funicular location of descending axons. 3. The RSNs were classified into the following four groups; (1) mRSNs which descended in the medial part of the ventral funiculus, (2) in RSNs which descended in the ventrolateral funiculus, (3) 1RSNs which descended in the dorsal 2/3 of the lateral funiculus and (4) coRSNs which descended in the contralateral funiculi. The mRSNs were located in a fairly localized region corresponding to the nucleus reticularis pontis caudalis (N.r.p.c.), while inRSNs, 1RSNs and coRSNs were mainly in the nucleus reticularis gigantocellularis (N.r.g.), in the nucleus reticularis magnocellularis (N.r.m.) and in the nucleus reticularis ventralis (N.r.v.). RSNs were further divided into three types depending on the levels of projection. L-RSNs projected to the lumbar spinal segments. C-RSNs descended to the C6–C7 spinal segment but not to the lumbar segments. N-RSNs projected to the C3 but not to the C6–C7 segments. 4. Stimulation of the tectum and the cerebral peduncle produced monosynaptic negative field potentials in the medial two thirds of the reticular formation in the pons and medulla. Tectal field potentials were largest in the N.r.p.c. and the rostral part of the N.r.g., while pyramidal field potentials were largest in the N.r.g. Correspondingly, RSNs in the N.r.p.c. (mRSNs) received larger monosynaptic EPSPs from tectal than from pyramidal volleys, while RSNs in the N.r.g. (in-, 1- and coRSNs) received stronger input from the peduncle than from the tectum. 5. Stimulation of the C7 ventral but not the lateral funiculus evoked monosynaptic EPSPs on all the dorsal neck motoneurones tested. Stimulation of the L1 segment only produced monosynaptic EPSPs in 35% of the motoneurones. The L1 evoked EPSPs were much smaller than C7 evoked EPSPs. 6. The C7 evoked EPSPs (C7 EPSP) showed complete occlusion (collision) with the tectal or pyramidal disynaptic EPSPs. Similar results were obtained with L1 EPSPs. These results indicate that tectal and pyramidal disynaptic EPSPs in dorsal neck motoneurones were mediated chiefly by C-mRSNs and C-inRSNs and partly by L-RSNs.

Notes: Summary A class of interneurons in the cat abducens nucleus was identified by its antidromic activation from the contralateral ascending MLF, disynaptic activation from the contralateral vestibular nerve and type II response to rotation of the turntable. They were also activated antidromically from the contralateral oculomotor nucleus, the region of medial rectus motoneurons. Extracellular spikes of single interneurons, spontaneous or glutamate-driven, were used as triggers for perior post-spike averaging of three kinds of potentials. (1) The average of the extracellular field potentials within the contralateral oculomotor nucleus consisted of an early positive or positive-negative spike and a late, slow negative wave. The early spike was an action current caused by impulses along the axon of the interneuron. The late potential was the extracellular counterpart of unitary EPSPs. (2) The averaged membrane potential of contralateral medial rectus motoneurons revealed unitary EPSPs with monosynaptic latencies, evidence that interneurons were excitatory in nature. (3) The average of compound potentials of the contralateral medial rectus nerve showed a monosynaptic excitatory effect relevant to unitary EPSPs. This effect was observed with nearly all interneurons. All interneurons thus identified exhibited discharge patterns closely correlated with the activity of medial rectus motoneurons in both slow and quick phases of vestibular nystagmus. It was concluded that these interneurons controlled activities of contralateral medial rectus motoneurons associated with conjugate horizontal eye movements by their monosynaptic excitatory connections.

Notes: A series of new polyimides containing fluorinated alkoxy side chains are prepared from novel fluorinated alkoxy diamines. The dieletric constant at 1 kHz in the fluorinated polyimides decreases from 3.3 to 2.6 as fluorine content increases. The refractive index also changes from 1.58 to 1.48, dependent on the fluorine content. In addition, the fluorinated polyimides exhibit lower water absorption than the reference polyimides prepared from m-phenylenediamine.

Notes: High-pressure Raman spectra of liquid and solid ethanol were measured at pressures up to 17 GPa and 300 K in a gasketed diamond anvil cell. The frequencies of in-phase and out-of-phase O—H stretching vibrations which characterize the hydrogen bond along the zig-zag chain decrease with increasing pressure with slopes(dν/dP) of -14.3 and -12.4 cm-1 GPa-1, and they overlap with the CH stretching mode at about 11 and 17 GPa, respectively. No solid-solid phase transition was observed at pressures up to 17 GPa.