Electrophysiological analysis of potential arginine vasopressin projections to the ventral septal area of the rat

Extracellular electrophysiological studies of neurons in the ventral septal region of the rat have examined afferent input from the paraventricular nucleus, bed nucleus of the stria terminalis and suprachiasmatic nucleus. Short latency excitatory or inhibitory orthodromic potentials were obtained following electrical stimulation of each nucleus, thereby providing evidence for these areas as a possible source of arginine vasopressin (AVP) fibers to the ventral septal region. These projections may mediate the reported antipyretic action of arginine vasopressin in the ventral septal region.     

Paradoxical ventricular septal motion with right ventricular dilatation as a manifestation of pure pressure overload due to pulmonary veno-occlusive disease

Paradoxical interventricular septal motion with right ventricular dilatation has been considered the hallmark of right ventricular volume overload. We report a 43-year-old woman with severe pulmonary hypertension due to pulmonary veno-occlusive disease who exhibited these echocardiographic abnormalities. Right ventricular volume overload was excluded by physical examination, echocardiography with saline contrast study and by cardiac catheterization, angiography, and shunt study. These echocardiographic findings are thus not pathognomonic of right ventricular volume overload and can be seen with pressure overload as well.     

Field dependent transverse relaxation rate increase may be a specific measure of tissue iron stores

The degree to which MRI magnet field strength affects measured transverse relaxation rates (R₂) defines a measure termed the field dependent R₂ increase (FDRI). We report here the results of in vivo and in vitro experiments that were conducted to evaluate whether FDRI is a potentially useful measure of tissue iron stores. T₂ relaxation times were obtained using two clinical MRI instruments operating at 0.5 and 1.5 Tesla, and relaxation rates (R₂) were calculated as the reciprocal of T₂. The in vivo experiment measured R₂ in human brain frontal white matter, caudate nucleus, putamen, and globus pallidus. The FDRI was very highly correlated with published brain iron levels for the four regions examined. The in vitro experiment measured R₂ in agarose gel-based phantoms containing physiologic forms and amounts proteins involved in iron storage and transport (ferritin, apoferritin, transferrin, and apotransferrin). Significant field dependence was observed only for the ferritin phantoms. The differences in the R₂ values obtained at the two field strengths were striking, and were proportional to the ferritin levels of the phantoms. These studies suggest that FDRI may be a specific measure of tissue ferritin. The quantitative significance of the results to imaging and possible applications to the clinical investigation of pathologic states are discussed.     

Unusual ``Midseptal' Sinus Venosus Defect

An unusual case of an interatrial communication similar to a sinus venosus defect associated with an overriding pulmonary venous chamber is reported. There was no direct connection of the pulmonary venous system with either the superior vena cava or the low right atrium, as is usual with sinus venosus defects. This defect may represent the result of a sinus venosus defect associated with cor triatriatum.     

急性脑缺血后脑隔——视前区内性功能调节相关神经元的变化

目的探讨急性脑缺血后出现性功能障碍的机理。方法应用蒙古沙土鼠急性脑缺血再灌注模型，对脑隔—视前区内性功能调节相关神经元光镜和电镜下的病理组织学和超微结构改变进行了观察。结果缺血５分钟再灌注造成的神经元密度和亚细胞水平的结构变化是暂时的，可在２周内恢复，１０分钟脑缺血再灌注后神经元的损害加重，且在２周后尚未恢复，损害主要为膜结构如线粒体、内质网等破坏。结论神经元损伤程度与缺血时间及再灌注时间长短密切相关，脑隔—视前区内神经元的病理损害是引起性功能障碍的重要形态学依据。     

心肌梗塞后室间隔穿孔的手术治疗

探讨急性心肌梗塞后室间隔穿孔的手术时机选择及影响手术疗效的因素。１６例急性心肌梗塞后室间隔穿孔病人接受了手术治疗。平均年龄５４．５岁。术前合并心源性休克５例，充血性心力衰竭伴肺水肿１例。１４例行冠状动脉造影，单支病变８例，多支病变６例，合并室壁瘤１３例。急症手术４例，择期手术１２例。行穿孔直接缝合２例，补片修补１３例，双侧补片修补１例；同期冠脉搭桥９例，室壁瘤切除或折叠１３例。术后应用主动脉内球囊反搏（ＩＡＢＰ）者８例。２例急症手术者早期死亡。结论：室间隔穿孔应先行内科治疗控制心源性休克，包括应用ＩＡＢＰ或左心室辅助等，使病人能坚持到穿孔４８小时后再积极手术。分流量小者应延至３～６周后手术。心源性休克是影响术后早期死亡率的主要因素     

Differential Seasonal Regulation of Melatonin Receptor Density in the Pars Tuberalis and the Suprachiasmatic Nuclei: A Study in the Hedgehog (Erinaceus europaeus, L.)

Using quantitative autoradiography, we have studied the seasonal changes of high affinity melatonin receptor density in both the SCN and PT of the hedgehog, a seasonal breeder and an hibernator. Animals in 3 different physiological states were studied: sexually active animals, and sexually inactive animals during the hibernation period, being then either euthermic or hypothermic. In sexually active animals, B_maax were 75.8 ± 7.1 fmol/mg protein in PT and 9.1 ± 0.5 fmol/mg protein in SCN; and Kd values were: 94 ± 22 pM in the PT and 101 ± 15 pM in the SCN. This specific binding was strongly decreased in the PT of sexually inactive animals. Moreover, this decrease was significantly stronger in hypothermic than in euthermic hedgehogs. Saturation studies and Scatchard analysis revealed that the observed decrease in the PT resulted from change in the B_max but not in the Kd, B_max values being respectively 56.4 ± 5.9 and 29.5 ± 1.9 fmol/mg protein in euthermic and hypothermic sexually at rest animals. In none of the different physiological states, did the density of melatonin receptors of the SCN show any changes, B_maax values being respectively 9.8 ± 0.5 and 9.8 ± 0.4 fmol/mg protein in euthermic and hypothermic sexually at rest animals. This shows for the first time a tissue-specific regulation of melatonin receptor density occurring in the PT but not in the SCN. Furthermore, this decrease of binding in the PT is correlated with both sexual inactivity and hibernation period. This strongly suggests that the mediation of the photoperiodic effect on seasonal functions like seasonal hypothermia and reproduction involves an effect of melatonin on the PT rather than on the SCN.     

Electrophysiology of the pigeon's habenular nuclei: Evidence for pineal connections and input from the visual system

Single unit electrical activity was recorded from neurons in the habenular nuclei of pigeons. The neurons were initially classified according to their responses to single shock stimulation of the pineal organ and subsequently according to their response following stimulation of the optic chiasma. The cells were also tested for changes in the level of spontaneous activity in response to illumination of the lateral eyes and the exposed dorsal surface of the brain. In response to electrical stimulation at the two sites, cells were either orthodromically activated or inhibited or unaffected by the stimulus. No antidromic responses to stimulation of either site were observed. The results show that habenular neurons receive excitatory and inhibitory afferent fibres from both regions. Evidence is provided for a substantial convergence of either excitatory or inhibitory inputs onto many of these cells. Both excitatory and inhibitory responses to photic stimulation were observed, although almost half of the neurons were unresponsive. No significant relationships were found between response combinations to electrical stimulation at either site and the effects of illumination. This suggests that neither of the afferent pathways demonstrated are primarily concerned with the transfer of photic information.     

Corticofugal actions on the lateral cervical nucleus of the cat

The question of possible corticofugal actions on the lateral cervical nucleus (LCN) of the cat was reinvestigated. Recordings were made from single relay cells, identified histologically as lying in the LCN which was deafferented by spinal cord lesions to avoid interference from corticospinal-cervical pathways. Intracortical stimulation of the contralateral sensorimotor cortex inhibited all 53 cells studied, but in addition excited only 25% of them (mean latency 5 ms). Cortical stimulation also inhibited mass transmission through the LCN. Care was taken to avoid inhibition due to stimulating high-threshold receptors in the head. Exploration with the stimulating electrode of large parts of the cerebral cortex allowed lowest threshold (45 to 90 μA; 10 ms train of cortical shocks of 1 ms duration at 500 Hz) zones for inhibition of the LCN to be located, but no low-threshold zones for excitation could be found. (Indirect current spread with such stimulation of the cortex was shown to be about 1.5 mm.) Histological reconstruction of the stimulating tracks showed that the low-threshold zone was cylindrical, rostrally, lying in the grey matter of that part of the cytoarchitectural area 3a which represents the face. Caudally, the low-threshold zone was in white matter where the corticofugal pathway would be expected to course. Such a nonsomatotopically organized inhibitory pathway is unusual in sensory systems and suggests that the LCN may be involved in certain tasks requiring face-limb coordination.     

Projections from the superior olivary complex to the cochlear nucleus in the tree shrew

The origins and targets of projections from the superior olivary complex to the cochlear nuclei were studied in the tree shrew by placing small injections of horseradish peroxidase (HRP) in the cochlear nucleus and small injections of ³H-leucine in the superior olivary complex. The results show that the descending pathways originate in periolivary cell groups surrounding the medial and lateral superior olives and that the periolivary nuclei differ from one another in their patterns of projections to the cochlear nucleus. For example, cell groups may project either ipsilaterally or bilaterally. Cells in the lateral nucleus of the trapezoid body project only to the ipsilateral cochlear nucleus. Other periolivary cell groups project bilaterally, although some of these may project more heavily to one side than the other. Some pathways have widespread targets in the cochlear nucleus whereas others have relatively specific targets. Diffuse projections to all divisions of the cochlear nucleus arise from the lateral nucleus of the trapezoid body ipsilaterally and from the medial perioliviary nucleus bilaterally. The targets of other descending pathways are more restricted. The anterolateral, dorsal, and dorsolateral periolivary nuclei project mainly to the anteroventral cochlear nucleus; the ventral nucleus of the trapezoid body and the posterior periolivary nucleus project mainly to the dorsal and posteroventral cochlear nuclei. All of these specific projections are bilateral. These results suggest that projections from the periolivary cell groups to the cochlear nucleus consist of multiple components with different degrees of specificity.