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.     

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.     

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.     

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).     

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.     

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.     

Modification of the prompts in the CISD model for bereavement in the workplace

When a death of an employee occurs, surviving co-workers can be severely impacted, affecting their ability to focus productively on their jobs. Critical Incident Stress Management (CISM) providers may occasionally be called to provide services in these situations (regardless of whether or not the death was a violent one). A modification of the prompts of the CISD debriefing model is presented as a method of responding to bereavement in the workplace.     

An analysis of the axon populations in the nerves to the pelvic viscera in the rat

The present study uses selective surgical ablations combined with electron microscopic analyses to determine the number of axons in yarious catagories in rat hypogastric, pelvic, and pudendal nerves, these being the nerves to the pelvic viscera in this animal. Unmyelinated fibers predominate in all of these nerves. One of the most significant findings is that the pelvic nerve contains almost as many postganglionic sympathetic fibers as the hypogastric nerve. Previous investigators thought that the pelvic nerve supplied the parasympathetic inflow and the hypogastric nerve the sympathetic inflow to the pelvic viscera. The finding that there is a sizable sympathetic component in the pelvic nerve negates this idea, at least for the rat, and presumably calls for a reevaluation of the syndromes that arise from pelvic as opposed to hypogastric nerve section. Other findings of interest are (1) that there are unmyelinated efferent axons in the pudendal nerve, indicating that the pudendal is not a typical somatic nerve, (2) that the hypogastric nerve has a very small sensory component, and (3) that there are fibers surviving in the distal stumps of all these nerves, particularly the pelvic and hypogastric nerves.     

Psychosine-induced changes in neuromuscular transmission and in the structure of the neuromuscular junction in the frog]

A decrease in the amplitude of miniature and evoked end-plate potentials (MEPPs and EPPs) as well as changes in EPP facilitation and depression during frequency stimulation were observed in psychosine-treated m. cutaneous-pectoris of the frog. Electron-microscopic investigation demonstrated severe changes in synaptic Schwann cells embracing motor terminals and disturbances in the inner mesaxon structure of the myelinated parts of motor terminals.     

Microheterogeneity in the distribution of the 844ins68 in the cystathionine beta-synthase gene in Italy.

Cystathionine beta-synthase (CBS) is an important enzyme for methionine metabolism. A common 844ins68 insertion variant in the CBS gene has been described. This 68-bp duplication of the intron 7-exon 8 boundary within the CBS gene already has been reported to be associated in cis with the T833C mutation. Heterozygosity for CBS deficiency is considered an important cause of hyperhomocysteinemia that strongly relates to cardiovascular disease, as well as homozygosity for another common variant, the C677T mutation of 5,10-methylene tetrahydrofolate reductase. We analysed the prevalence of the 844ins68 variant in the CBS gene in 595 unrelated apparently healthy individuals from nine Italian regions and in 133 patients with coronary artery disease. Our data confirm that the T833C mutation cosegregates in cis with the 844ins68 in all carriers of the insertion. Furthermore, no statistical difference was found in the insertion variant allele frequency between controls and coronary artery disease patients. Our study indicates a microheterogeneity in the distribution of the 844ins68 in the Italian population.