Inhomogeneities in the propagation of the slow wave in the stomach

The propagation of the slow wave in the stomach and its role in inducing sweeping peristaltic contractions toward the pylorus, essential for a proper digestion and emptying, have been studied for many years. Irregularities in the timing or in the pattern of propagation of the slow wave have been known to induce various gastric malfunctions and, recently, several types of gastric dysrhythmias have been described which could lead to gastric contraction abnormalities. In this study, Du et al. have analyzed the disturbances caused by a simple transmural incision in a human stomach, performed to obtain a biopsy of the muscle, on the propagation pattern of the slow wave. In addition, they show that such an incision may by itself also induce new types of gastric dysrhythmias. These results are important in demonstrating that the function of the stomach can easily be disturbed by such procedures. This mini‐review describes several ways in which inhomogeneities in propagation may affect the conduction pattern of the slow wave, including the genesis of several dysrhythmias, and what is currently known about their impact on gastric contraction and digestion.     

Early stages in the formation of the cerebellum in the frog

The formation of the cerebellum was studied during the first 6 months of the tadpole stage of the bullfrog by using standard histological methods and reconstructions from serial horizontal sections. Three major developmental phases were noted in the formation of the cerebellum. (1) During the first 5 weeks of development, the neuroepithelium proliferated and the dorsal mesencephalic plates increased in size. (2) Starting in the sixth week, a patch of neuroepithelium began to differentiate and gave rise to a small population of Purkinje cells. In subsequent weeks, the area of differentiation continued to spread and a Purkinje cell layer became established along the dorsal margin of the cerebellar plate. (3) In the 12th week, the ventrolateral part of the cerebellar plate began to increase in size and generate two populations of small cells. The lateralmost part of the neuroepithelium in this area generated a group of cells that formed an external granular layer that was one cell deep. Cells of this external granular layer migrated inward into the primitive molecular layer, and by the 26th week only a remnant of an external granular layer remained in the cerebellum. The more medially situated part of the neuroepithelium gave rise to another population of small cells that formed a column, which appeared to be continuous with the Purkinje cells, but differed from them in size. It should be noted that full maturation of the cerebellum occurs during metamorphosis, which in this species remains some 2 years away.     

Cells in the pretectal olivary nucleus are in the pathway for the direct light reflex of the pupil in the rat

Extracellular microelectrode recordings from 148 single cells in the pretectum of the hooded rat were classified according to their temporal response properties to light stimulation of their retinal receptive fields. Fifty-six cells were classified as tonic-on cells, 22 cells were classified as tonic-off cells, and 53 cells were classified as phasic cells. Seventeen cells could not be assigned to one of these 3 groups. The diameters of the receptive field centers of the tonic-on pretectal cell were clustered about a mean of 31° and the temporal response of these cells was sustained. Constriction of the contralateral pupil was produced by electrical stimulation through the recording electrode at sites containing tonic-on pretectal cells, but not at sites containing tonic-off pretectal cells or phasic pretectal cells. For this reason, we argue that tonic-on cells are likely to mediate constriction in the light reflex of the rat's pupil. Receptive field maps together with electrolytic marking lesions at recording and stimulation sites showed that tonic-on pretectal cells are retinotopically organized and are aggregated in a strip running from the dorso-medial tip of the pretectum to the ventro-lateral boundary. The anatomical distribution of these cells is coextensive with the region known as the pretectal olivary nucleus (PO) in the rat^26,27.Using fine microelectrodes, recordings were obtained from 27 axons presumed origin (fibers). Of these, 14 were tonic-on, 10 were phasic, 2 were tonic-off, and 2 were unclassified. Recordings from tonic-on fibers were obtained near tonic-on pretectal cells, typically in the most dorsal light-responsiveness region of the pretectum. These fibers were activated by single pulse electrical stimulation of the optic chiasm. The mean receptive field center diameter of 6 tonic-on fibers was 10.1°, or about a factor of 3 less than that of pretectal tonic-on cells. The mean conduction velocity of 14 tonic-on fibers was 3.1 m/s.We argue that the tonic-on cells of the PO serve to integrate signals from tonic-on center retinal ganglion cells with adjacent receptive fields to provide signals for constriction of the pupil to neurons in the oculomotor nucleus.     

Organization in the descending tracts of the dorsolateral funiculus in the cat

Organization of the fibers in the descending tracts of the dorsolateral funiculus of the cervical spinal cord was investigated in cats. The spinal cord was penetrated with microelectrodes at 400 mum intervals in the medio-lateral direction at the c5/c6 and c6/c7 segmental borders. Silicon substrate microelectrodes with a linear arrangement of activated iridium contacts were used. The stimulus consisted of a 20 ms train of charge balanced biphasic current pulses at 330 Hz. The evoked activities from selected forelimb muscles were acquired into computer. Only the data points with an activation threshold of less than 35 muA were considered in the analysis. Muscle contractions were mostly in the form of short twitches. In both spinal segments, an area of high threshold was found in the middle of the dorsolateral funiculus. Majority of the muscles studied had a dorsal or ventral concentration of activation points. The distal muscles were mostly activated in the ventro-lateral aspect of the funiculus, while the elbow muscle maps spread to both dorsal and ventral sides. These results show a functional organization in both cervical segments studied, with overlapping regions between the areas dedicated for each forelimb muscle.     

Dysthymic disorder in the aged in the community

Summary The prevalence of dysthymic disorder and and its relationship to social and health variables were investigated in a Finnish population aged 60 years or over. The prevalence was lower in men (17.2 per 100) than in women (22.9 per 100). In the total population the occurrence was higher in the widowed (24.9 per 100) than in the married (18.3 per 100). In men, dysthymic disorder was more common in those with a lower educational level (22.6 per 100) than with a higher educational level (15.1 per 100), and more common in persons receiving long-term institutional care or home nursing or home help (28.7 per 100) than in persons living independently at home (14.6 per 100). The rate was not related to age, marital status or occupation. In women, the occurrence was not related to age, marital status, education, occupation or form of social and health care. The female rate was higher than the male in the older group (70 yrs. +), in married persons, in those with a higher educational level and in those living independently at home. Underdiagnosing was evident. The occurrence of dysthymic disorder was related to poor health and poor functional status and to the occurrence of social and health stressors. No differences were found in the occurrence of the related factors between persons with dysthymic disorder and persons with major depression. Our results support the conclusion that the majority of cases of dysthymic disorders in the elderly are affective illnesses and not personality disorders.     

Issues in the assessment of outcome in depressive illness in the elderly

Different approaches to assessment of outcome of psychiatric illness generally are critically appraised. The article examines research design, outcome criteria and statistical analysis, including newer statistical approaches. Measurement of outcome is complex and a more detailed and sophisticated approach needs to be adopted than in the past. Some of the special problems associated with outcome studies of depressive illness in the elderly are discussed. Specific recommendations are suggested for future outcome studies of depression in the elderly. Such studies should be prospective, recruit a wide range of patient severity and make greater use of newer statistical analyses, eg survival analysis and proportional hazards model. Outcome criteria should be precisely defined, measured using standardized instruments and be comprehensive (clinical, physical health, psychosocial, etc.). Attention should be given to inter-episode symptomatology.     

Changes in the mitochondria in the initial part of the axon during regeneration

Summary The initial part of the axon including the axon hillock, the initial unmyelinated segment and the beginning of myelinated axon was studied electron microscopically during regeneration, 1–30 days following a crush lesion of the rat hypoglossal nerve. Large mitochondria reaching 1.1 m in diameter, with abundant cristae and dense granules in the matrix were observed between days 3–21. They formed clusters in the initial myelinated segment of the axon. End-to-end contacts and ribosomes around them were very often visible.The large mitochondria exhibited strong succinate dehydrogenase and NAD · H₂ diaphorase activities.The relationship between the appearance of large and active mitochondria in the initial part of the axon and the elevated axonal transport during regeneration of the peripheral nerve is also discussed.     

Experiences in the United States--a difference in the status in the United States and that in Japan]

Child and adolescent psychiatry has been established as a subspecialty in the United States. The systematic education, training and research opportunities are currently available and child and adolescent psychiatry is a major part of psychiatric practice in the US. However, there are many burdens to overcome to provide adequate child mental health care. Several important focus on child mental health care in US are to 1) improve the assessment of and recognition of mental health needs in children, 2) promote scientifically-proven and evidence based interventions and 3) increase access to and coordination of quality mental health care services. To understand the current status and problems in child and adolescent psychiatry in US may help the Japanese psychiatrists to develop and establish child and adolescent psychiatry in Japan.     

Apoplexy in the everyday practice in the eighteenth century

We report the original recipes applied to treat apoplexy in the eighteenth century, as written in the personal notes of doctor of that century.     

Asymmetry in the structural organization of the ganglion layer of the retina in the frog

Silver-impregnated retinal preparations were used to study the distribution density and topographic features of small and large ganglionic cells (GC) of Rana ridibunda and Rana temporaria. For both species the increased density of GC (a streak) stretched higher than the naso-temporal axis passing through the optic disk. Beyond the streak the density of small GC was maximal in the central zone of the retina and decreased towards its periphery. For the upper quadrants of the retina the density of small GC was higher than that for the lower ones by 26% on the average. On the contrary, the density of large GC was higher in the lower part of the retina as compared to the upper one, the difference being more pronounced for R. temporaria. The density of large GC was also asymmetric with respect to the dorso-ventral axis being higher in nasal quadrants than in temporal ones by 40-55%. The highest density of large GC was found in the middle zone of the retina. The found structural asymmetry in the retinal output raster may bear an adaptively ecological meaning and may condition the particularities of the formation of the visually guided prey-catching and avoidance reactions.     

Local nonuniformities in the syncytium of the horizontal cells of the retina in the turtle

Electrical coupling between horizontal cells of the turtle retina was investigated by means of two microelectrodes (current and recording ones) penetrating neighbouring cells at a fixed distance from each other. The morphological coupling was revealed by means of fluorescent dye Lucifer Yellow. The electrical coupling was confirmed between elements of similar type (L1--axonal terminals, or L2--cell bodies, or R/G type cells) and no coupling was found between elements of different types, though L1 and L2 are directly connected through thin axons. In the L1 syncytium the electrical coupling at small (less than or equal to 50 microns) but fixed distances between microelectrodes could differ several times depending on the minimal displacement of microelectrodes. This local nonuniformity of coupling can be explained on the basis of structural nonuniformities in the L1 (axon terminal) network. It is unlikely however that the structural nonuniformities can influence the functional properties of horizontal cell network when the retina is stimulated adequately (by light).     

Increase in GABAergic Cells and GABA Levels in the Spinal Cord in Unilateral Inflammation of the Hindlimb in the Rat

The effects of chronic peripheral inflammation on spinal cord γ-aminobutyric acid (GABA) were examined in the rat. Following the injection of complete Freund's adjuvant in the left hindlimb footpad an increased number of immunoreactive cells occurred in ipsilateral laminae I-III of the dorsal horn from L3 to L5. GABA-immunoreactive cells were more numerous than contralaterally 1 week after the onset of the inflammation, reached maximal numbers after 3–4 weeks, and declined thereafter. Differences from control sides were statistically significant except at week 6. GABA levels in homogenates of the ipsilateral lumbar enlargement were increased significantly at 4 weeks. Since increases in GABA occurred in the spinal cord zone of projection of the nerves supplying the inflamed foot, the central response is surmised to result from the increased nociceptive input arriving from the periphery. However, the transmission from primary axons to GABA interneurons is not likely to be monosynaptic since profiles containing glutamate decarboxylase or GABA immunoreactivity are known to be predominantly presynaptic, and rarely postsynaptic, to primary afferent endings in electron micrographs in the rat. The findings support the function attributed to spinal GABA in modulating nociceptive input at segmental level.     

Pursuit of the origin of the large myelinated fibers of the anterolateral funiculus in the spinal cord in humans in relation to the pathomechanism in amyotrophic lateral sclerosis

To determine the origin of the large myelinated fibers in the anterolateral funiculus (ALF) in the spinal cord of humans, myelinated fibers in the ALF of the mid-cervical spinal cord were examined quantitatively. Five groups of subjects were examined, consisting of control subjects, patients with cerebral lesions and showing complete degeneration of the unilateral/bilateral pyramis of the medulla oblongata, those with lesions of the pontine tegmentum, those with lesions of the lower cervical spinal cord, and those with thoracic/lumbar lesions. The results indicate that the large myelinated fibers in the ALF of the mid-cervical spinal cord of humans originate from the tegmentum of the brain stem and the lower cervical spinal cord, and not from the cerebrum, or the thoracic or lumbar spinal cord. Thus, they are descending fibers from the brain stem tegmentum and ascending fibers from the lower cervical cord, and not corticospinal tracts or long-ascending fibers from the thoracic or lumbar spinal cord. The origin of the large myelinated fibers in the ALF of the spinal cord in humans, the number of which was severely decreased in patients with amyotrophic lateral sclerosis, is considered to be the long-descending neurons in the brain stem tegmentum and the propriospinal neurons in the spinal cord. Received: 23 December 1998 / Revised, accepted: 29 March 1999     

Variations in the 5-hydroxyindoleacetic acid concentration in the cerebrospinal fluid during the sleep-wake cycle in man

A variation in the ventricular fluid 5-HIA A concentration has been observed during the phases of the sleep-wake cycle in man. This variation affects the NREM phase, during which 5-HIAA increases markedly, rather than the waking state and the REM phase. The results are discussed in relation to the possible relevance of serotonin to the sleep mechanism.

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Sommario Durante le fasi del ciclo sonnoveglia nell'uomo è stata osservata una modificazione della concentrazione dell'acido 5-HIAA nel liquido ventricolare. Tale modificazione interessa prevalentemente la fase NREM del sonno, durante la quale il 5-HIAA aumenta in misura rilevante, rispetto alla condizione di sveglia e di sonno REM. I risultati vengono discussi in relazione alla possibile implicazione della serotonina nel determinismo del sonno.

     

Changes in the calcium action potentials of the neurons of the spinal ganglia in the rat in response to divalent cation substitution in the extracellular medium

Rat dorsal root ganglion neurons were investigated by intracellular microelectrodes using current clamp technique. After elimination of sodium ions from the extracellular medium and addition of TEA pure "calcium" action potentials were recorded. Progressive and selective disturbance of such potentials was observed during continuous intracellular recording indicating a decrease in the calcium conductance while sodium and potassium conductances remained uneffected. Such a disturbance is supposed to be due to excessive influx of calcium, strontium or barium ions into the cell. The calcium component of the action potential was also dependent on the stimulation frequency, such dependence being different for strontium or barium solutions. Possible participation of current-dependent inactivation in the origin of this phenomenon is discussed.     

Alterations in the distribution of glutathione in the substantia nigra in Parkinson's disease

Summary Depletion of reduced glutathione occurs in the substantia nigra in Parkinson's disease and in incidental Lewy body disease (presymptomatic Parkinson's disease) which may implicate oxidative stress in the neurode-generative process. In this study mercury orange fluorescent staining and immunostaining with an antibody to reduced glutathione have been used to determine the distribution of reduced glutathione in the substantia nigra in Parkinson's disease compared with normal individuals.Mercury orange staining showed moderate background levels of fluorescence in the neuropil in both control and Parkinson's disease substantia nigra and localised reduced glutathione to the somata of melanized nigral neurons and glial elements of the neuropil. Neuronal nuclei revealed a relative lack of fluorescence after mercury orange staining. There was a significant depletion of reduced glutathione in surviving neurons in Parkinson's disease compared to nerve cell populations in control tissue. Mercury orange fluorescence indicated a high concentration of reduced glutathione in a subpopulation of non-neuronal cells, most likely astrocytes or microglia.Immunohistochemical examination of nigral tissue from the same Parkinson's disease and control patients with an antibody to glutathione showed staining in neuronal perikarya and axonodendritic processes of melanized nigral neurons which was generally most intense in control neurons. Moderately intense staining of the background neuropil, most prominent in control nigras, and staining of capillary walls was also detected. Intense staining was seen in cells with the morphological features of glial cells in both control and PD nigra.These data show a significant presence of reduced glutathione in the cell bodies and axons of nigral neurons. They are in agreement with biochemical studies showing depletion of reduced glutathione in substantia nigra in Parkinson's disease, and indicate a significant loss of neuronal reduced glutathione in surviving nigral neurons in Parkinson's disease.Abbreviations GFAP glial fibrillary acidic protein - GSH reduced glutathione - GSSG oxidized glutathione - ILBD incidental Lewy body disease - PBS phosphate-buffered saline - PD Parkinson's disease     

Projections to the putamen from neurons located in the white matter and the claustrum in the macaque

Continuing investigations of corticostriatal connections in rodents emphasize an intricate architecture where striatal projections originate from different combinations of cortical layers, include an inhibitory component, and form terminal arborizations which are cell-type dependent, extensive, or compact. Here, we report that in macaque monkeys, deep and superficial cortical white matter neurons (WMNs), peri-claustral WMNs, and the claustrum proper project to the putamen. WMNs retrogradely labeled by injections in the putamen (four injections in three macaques) were widely distributed, up to 10 mm antero-posterior from the injection site, mainly dorsal to the putamen in the external capsule, and below the premotor cortex. Striatally projecting labeled WMNs (WMNsST) were heterogeneous in size and shape, including a small GABAergic component. We compared the number of WMNsST with labeled claustral and cortical neurons and also estimated their proportion in relation to total WMNs. Since some WMNsST were located adjoining the claustrum, we wanted to compare results for density and distribution of striatally projecting claustral neurons (ClaST). ClaST neurons were morphologically heterogeneous and mainly located in the dorsal and anterior claustrum, in regions known to project to frontal, motor, and cingulate cortical areas. The ratio of ClaST to WMNsST was about 4:1 averaged across the four injections. These results provide new specifics on the connectional networks of WMNs in nonhuman primates, and delineate additional loops in the corticostriatal architecture, consisting of interconnections across cortex, claustralstriatal and striatally projecting WMNs.     

Role of the subthalamo-nigral input in the control of amygdala-kindled seizures in the rat

The substantia nigra pars reticulata (SNpr) is a critical site for the control of epileptic seizures. Potentiation of the inhibitory GABAergic input from the striatum to the SNpr suppresses primary or secondary generalized seizures in the rat. The purpose of this study was to examine the possible involvement of the excitatory glutamatergic input from the subthalamic nucleus to the SNpr in the control of both the electroencephalographic and the motor components of amygdala-kindled seizures in the rat. Microinjections of either an N-methyl- -aspartate (NMDA) antagonist in the substantia nigra or a GABA_A agonist in the subthalamic nucleus, significantly reduced motor seizures but did not modified the afterdischarges. These results provide evidence for the involvement of the subthalamo-nigral projection in the modulation and the propagation of the motor components of amygdala-kindled seizures.