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.     

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).     

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.     

Challenges in the Management of the HIV Patient in the Third Decade of AIDS

The epidemic of AIDS has been increasingly recognized as a major health and socioeconomic problem, not only in the United States or Africa, but also the rest of the world. The face of the epidemic has changed. The role that mental health providers play has also significantly grown as the epidemic continues on. Prior to the introduction of Highly Active Anti-Retroviral Therapy (HAART) and other advances in HIV care, the patients faced issues that related to death and dying. These advances brought with them renewed hope and resurrected lives. The patients fought with issues related to living new lives with HIV no longer an imminent death threat. In the third decade of AIDS, the struggles of the post-HAART era continue but bring with it more challenges. Mental health providers need to familiarize themselves with these issues so that they can better help HIV patients cope with this devastating disease.     

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.     

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.     

Patterning in the regeneration of electroreceptors in the fin of Kryptopterus

The influence of the target tissue on afferent nerve regeneration was studied in the adult glass catfish, Kryptopterus. In this fish, electroreceptors in the anal fin are distributed in a characteristic pattern in the proximal part of the fin and are absent in the distal portion of the fin. We tested whether axons were more likely to induce electroreceptors in certain regions of fin epidermis than in others. We rotated fin transplants so that the location of the degenerating electroreceptors was altered with respect to the regenerating axons in the host tissue dorsal to the fin. The effects of these rotations were observed in the living animal with differential interference contrast optics over a period of 10 weeks. When transplants were reversed rostrocaudally, new electroreceptors formed in the caudal half of the interradial zone, where degenerating electroreceptors were at the time of transplantation. When transplants were rotated so that the dorsoventral and rostrocaudal axes were reversed, some new receptors formed in the old target site regions that were located in the caudal interradial zones (in the distal half of the graft with respect to the host). Regenerating axons reached these regions of the transplant by taking unusual routes around the electroreceptor-free regions of fin. Very few electroreceptors formed in the distal/caudal or proximal/caudal interradial quadrants of grafts where the original orientation of the tissue was maintained. We suggest that old target sites have a neurotropic influence on the regenerating afferent axons and discuss the possibility that the distal fin epidermis is not as permissive to electroreceptor formation as proximal fin epidermis.     

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     

Selectivity between faces in the responses of a population of neurons in the cortex in the superior temporal sulcus of the monkey

There is a population of neurons in the cortex in the middle and anterior part of the superior temporal sulcus (STS) of the monkey with responses which are selective for faces. If, consistent with the effects of damage to the temporal lobe, these neurons are involved in face recognition or in making appropriate social responses to different individuals, then it might be expected that at least some of these neurons might respond differently to different faces. To investigate whether at least some of these neurons do respond differently to different faces, their responses were measured to a standard set of faces, presented in random sequence using a video framestore. It was found that a considerable proportion of the neurons with face selective responses tested (34/44 or 77%) responded differently to different faces, as shown by analyses of variance. An index of the discriminability of the most and least effective face stimulus (d') ranged between 0.2 and 5.0 for the different neurons. Although these neurons often responded differently to different faces, they did not usually respond to only one of the faces in the set, so that information that a particular face had been shown was present across an ensemble of neurons, rather than in the responses of an individual neuron. These findings indicate that the responses of these neurons would be useful in providing information on which different behavioral responses made to different faces could be based. These neurons could thus be filters, the output of which could be used for recognition of different individuals and in emotional responses made to different individuals.     

Heterogeneity in the coding in rat barrel cortex of the velocity of protraction of the macrovibrissae

Rats whisk to explore their environment and obtain information on object features, and the responses of somatosensory cortical neurones must precisely encode aspects of whisker movements. Using trapezoidal stimuli to deflect whiskers, with a wide range of velocities and amplitudes of whisker protraction, we recorded responses from a relatively homogeneous population of isolated cells and neuronal multiunits within the postero-medial barrel sub-field of somatosensory cortex, and analysed responses in an early post-stimulus-onset window. For 92% of neurones the function relating response strength to velocity was a saturating sigmoid but there were differences between neurones in the slopes and ranges over which responses changed. Responses of other neurones were non-monotonic, with response strength decaying at very high whisker deflection velocities. Generally, barrel cortex neurones were responsive to a much wider range of whisker protraction velocities than hitherto reported, especially to much slower velocities than generally assumed to be the main range of sensitivity. This carries implications for coding of whisker deflection velocity, a parameter that appears to be a significant information-bearing element of natural whisking. The effect of amplitude of deflection upon neural responses was evident in only approximately 24% of units and only when the dominant velocity effect had saturated.     

Sexual Dimorphism in the Distribution of a-Neoendorphin-Like Immunoreactivity in the Anterior Pituitary of the Rat

The localization of the opioid peptide α-neoendorphin (α-Neo-E) was studied in the anterior pituitary of normal and castrated male and normal female rats, Immunoreactive (ir) cells were noted in both sexes. These α-Neo-E-ir cells were further characterized using double immunostaining with an elution-restaining procedure. It was seen that in males, α-Neo-E-ir cells corresponded mainly to luteinizing hormone/follicle-stimulating hormone cells and a few thyroid-stimulating hormone (TSH) cells, whereas in females, virtually all α-Neo-E-ir cells corresponded to TSH cells. Castration of male rats caused, within 3 to 5 days, a dramatic decrease in the number of α-Neo-E-ir gonadotrophs, whereas the number of a-Neo-E-ir TSH cells tended to increase. Two weeks after castration, however, most α-Neo-E-ir cells were also follicle-stimulating hormone-ir. This study demonstrates that in the anterior lobe of the rat, α-Neo-E-ir is located within gonadotrophs and/or thyrotrophs, depending on the sex. In addition, results obtained following castration suggest that the expression of this peptide in the anterior pituitary depends upon the steroid environment, possibly indicating that α-Neo-E is implicated in the regulation of the pituitary-gonadal axis.     

综合性医院神经科门诊患者失眠情况的调查

目的调查综合性医院神经内科门诊患者失眠情况。方法采用病例对照研究和流行病学方法、根据美国精神疾病分类和诊断标准对2004年10～12月北京大学第三医院神经内科门诊患者的睡眠情况进行调查,并用多元Logistic回归模型分析影响睡眠的因素。结果共有925例患者完成调查,并分为急性失眠组(149例)、慢性失眠组(415例)和对照组(361例);对性别、吸烟、冠心病、高脂血症、文化程度、职业状况等混杂因素调整后行多元Logistic回归分析发现:(1)女性(OR=2.02,P=0.001)、前列腺增生症(OR=1.94,P=0.036)、焦虑(OR=3.29,P=0.000)、抑郁(OR=2.48,P=0.000)、腿动(OR=1.78,P=0.019)等与急性失眠显著相关;(2)女性(OR=2.13,P=0.000)、文化程度(OR=2.05,P=0.005;OR=2.07,P=0.003)、前列腺增生症(OR=1.71,P=0.023)、焦虑(OR=7.42,P=0.000)、抑郁(OR=4.73,P=0.000)等与慢性失眠显著相关。结论女性、前列腺增生症、焦虑、抑郁与急性和慢性失眠有相关性。     

The Role of Oxytocin Release in the Paraventricular Nucleus in the Control of Maternal Behaviour in the Sheep

Oxytocin (OT) release within the brain is thought to play a major role in inducing maternal behaviour in a number of mammalian species but little is known about the sites of release which are important in this respect. We have investigated whether the paraventricular nucleus of the hypothalamus (PVN) is a site of OT action on maternal behaviour in the sheep. In vivo microdialysis and retrodialysis was used to determine whether OT is released in the region of the PVN during the post-partum induction of maternal behaviour and if its release at this site can stimulate maternal behaviour in non-pregnant animals. In vivo sampling showed that OT concentrations increased significantly in the region of PVN at birth. When OT was retrodialysed bilaterally into the PVN (1 or 10 μM) of multiparous ewes treated with progesterone and oestradiol to stimulate lactation, maternal behaviour was induced in a significant number of animals (1 μM, 6/8 and 10 μM, 5/8) compared with controls (0/8 ewes). Similar infusions of the ring structure of OT, tocinoic acid (TOC—10 μM), also induced maternal behaviour in a significant proportion of animals (5/6 ewes) as did intracerebroventricular (ICV) OT (6/8 ewes) and artificial stimulation of the vagina and cervix (VCS, 8/9 ewes). On the other hand, vasopressin (AVP) 1 μM did not induce maternal behaviour in any ewes and a 10 μM dose only induced it in 2/8 animals. The neurochemical changes accompanying the above treatments were also investigated. Noradrenaline concentrations increased in the PVN after the retrodialysis administration of OT 1 μM and 10 μM, TOC 10 μM and AVP 1 μM, OT ICV and VCS. Dopamine concentrations were also increased by OT 10 μM, TOC 10 μM, AVP 1 μM and OT ICV. Aspartate and glutamate concentrations were significantly reduced by retrodialysis infusions of OT 1 μM and AVP 1 and 10 μM but not by any other treatment. Finally, the retrodialysis infusions of OT and TOC, as well as ICV OT, significantly increased plasma OT release whereas AVP infusions did not. These results provide evidence that OT is released in the PVN during parturition and is important for the induction of maternal behaviour. It seems probable that OT release at this site has a positive feedback effect on both parvocellular and magnocellular OT neurones to facilitate co-ordinated OT release both in central OT terminal regions (to facilitate maternal behaviour) and peripherally into the blood (to facilitate uterine contractions/milk let down). The potential functional roles for the actions of OT on monoamine and amino acid transmitter release in the PVN are discussed.     

The role of beta- and alpha-adrenoceptors in the regulation of the stages of the sleep-waking cycle in the cat

The effects of beta-adrenergic drugs alone and in combination with alpha-adrenergic drugs on the stages of the sleep-waking cycle were studied in adult cats. Polygraphic sleep recordings of 16 h showed that prenalterol (20 and 40 mg/kg i.p.), a beta 1-adrenoceptor-stimulating drug increased paradoxical sleep (PS) in a dose-related manner during 4-12 h. Salbutamol (40 mg/kg), a beta 2-adrenoceptor-stimulating drug, decreased PS during the first 4 h. Metoprolol (10 and 50 mg/kg), a relatively selective beta 1-adrenoceptor blocking drug, increased drowsy waking during the first 4 h. The larger dose also tended to decrease PS. Already at the lower dose metoprolol partially antagonized the PS increase produced by prazosin, an alpha 1-adrenoceptor blocking drug. Propranolol (5 mg/kg), a beta 1- and beta 2-adrenoceptor blocking drug, which alone decreases PS, antagonized the PS increase induced by phentolamine, an alpha 1- and alpha 2-adrenoceptor blocking drug. Atenolol (5 mg/kg), a poorly lipid-soluble beta-adrenoceptor blocking drug, failed to counteract phentolamine in increasing PS. Metoprolol (10 and 50 mg/kg) and propranolol (5 mg/kg) clearly potentiated the increase in drowsy waking and decrease in deep slow wave sleep and PS induced by clonidine (0.01 mg/kg), an alpha 2-adrenoceptor-stimulating drug. The results support the involvement of beta-adrenoceptors in the regulation of the sleep-waking cycle. A high level of beta-adrenergic activity may facilitate the production of PS. A low level of beta-adrenergic activity, especially in combination with a high level of alpha 2-adrenergic activity, may facilitate the production of drowsy waking. Central alpha 1- and beta 1-adrenoceptors may mediate opposite functions in the regulation of PS.     

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.     

Analysis of the habituation-like changes in transmission in the temporodentate pathway of the rat

Habituation-like decrements in extracellular measures of synaptic activation (population EPSP) and cell discharge (population spike) were analyzed in the dentate gyrus of the rat following repetitive low-frequency stimulation of the medial and lateral entorhinal cortex. Stimulation of either subdivision of the entorhinal projection system resulted in comparable habituation-like response decrements with similar stimulation regimens. However, habituating stimulation of one subdivision did not result in decreased responsiveness to stimulation of the other. Repetitive low-frequency stimulation or even a single pulse delivered to either subdivision did, however, result in a potentiation of granule cell discharge in response to stimulation of the other subdivision (a form of heterosynaptic potentiation). This heterosynaptic potentiation of granule cell discharge was not accompanied by any increase in the extracellular EPSP. Comparisons of the relationship between the population EPSP and population spike before and during habituating stimulation revealed changes in cell discharge in response to the habituating stimulus which could not be accounted for by changes in synaptic activation alone. The results suggest that repetitive activation of the temporodentate pathway alters granule cell output as a result of two processes, a habituation-like decrement in synaptic activation, and a potentiation of granule cell discharge as a consequence of prior activation.     

Role of the ventromedial hypothalamus in the regulation of adenohypophyseal immunoreactive dynorphin in the rat

In this study, we have examined the role of the dorsomedial (DMH), ventromedial (VMH) and arcuate (ARH) nuclei of the hypothalamus in the control of hypothalamic and pituitary immunoreactive (ir) dynorphin (Dyn) A and ir-Dyn B in the rat, by evaluating the effect of discrete, bilateral radiofrequency lesions in these structures. Lesions limited to the VMH reduced the content of ir-Dyn in the anterior pituitary but not in the neurointermediate lobe or in the hypothalamus. Gel chromatographic analysis of anterior pituitary extracts confirmed that ir-Dyn is mainly associated with high molecular weight forms containing Dyn A and Dyn B in their sequence. Anterior pituitary extracts of VMH-lesioned rats displayed a clearly lower proportion of these forms. Destruction of the DMH affected only the hypothalamic content of ir-Dyn; ablation of the ARH did not cause any significant change. Our results suggest that ablation of the VMH may disrupt critical neuronal connections to the median eminence originating in this nucleus or crossing it and participating in control of the adenohypophyseal pool of ir-Dyn.