Phagocytosis of erythrocytes in the subarachnoid space at spinal nerve exits

Summary Interdigitating cells (IDC) in the thymus of the spotless starling, Sturnus unicolor, were examined by electron microscopy. They occur principally in the thymic medulla and corticomedullary border. They possess an irregular nucleus and a perinuclear area of cytoplasm, containing most of the membranous organelles, surrounded by a peripheral electron-lucent zone. Clusters of smooth Golgi vesicles and complicated labyrinthine membrane-membrane contacts are the most characteristic cytological features. Birbeck granules are absent. Lymphocytes, plasma cells and even myoid cells can be found embedded in the cytoplasm. Immature elements, intermediate between epithelial-reticular cells and interdigitating cells, are tentatively identified as prointerdigitating cells. The functional significance of IDCs, and their phylogenetic significance in the vertebrate immune system, is discussed.     

Transpulmonary speed of sound input into the supraclavicular space.

The transpulmonary speed of sound input at the mouth has been shown to vary with lung volume. To avoid the disadvantages that exist in certain clinical situations in inputting sound at the mouth, we input sound in the supraclavicular space of 21 healthy volunteers to determine whether similar information on the relationship of sound speed to lung volume could be obtained. We measured the transit time at multiple microphones placed over the chest wall using a 16-channel lung sound analyzer (Stethographics). There was a tight distribution of transit times in this population of subjects. At functional residual capacity, it was 9 +/- 1 (SD) ms at the apical sites and 13 +/- 1 ms at the lung bases. The sound speed at total lung capacity was 24 +/- 2 m/s and was 22 +/- 2 m/s at residual volume (P < 0.001). In all subjects, the speed of sound was faster at higher lung volume. This improved method of studying the mechanism of sound transmission in the lung may help in the development of noninvasive tools for diagnosis and monitoring of lung diseases.     

Unsuccessful induction of low-zone tolerance to bovine serum albumin injected into the subarachnoid space

Introduction of T-dependent antigens into the subarachnoid space (isas) resulted in higher systemic antibody responses in mice than injections into the peritoneal cavity (ip) or other sites commonly used for immunization. Antibody production in isas immunized mice was not increased by treatment with cyclophosphamide (Cy) at doses known to abolish T-suppressor-cell activity, but such treatment increased antibody production in ip immunized mice toward the higher level which was observed in the isas immunized animals. Suppressor cell-dependent low zone tolerance (LZT) to TNP-BSA could not be induced by isas injections of deaggregated BSA (d-BSA). Conversely, mice which were unresponsive to ip injected d-BSA showed consistent systemic antibody responses when the antigen was injected isas. These observations indicate that immune responses initiated within the CNS are associated with relatively ineffective induction of systemic suppressor cell activity.     

Respiratory effects of H+ and dinitrophenol injections into the brain stem subarachnoid space of fetal lambs.

Mock cerebrospinal fluid (pH 5.37-8.38) or 2,4-dinitrophenol (DNP) (0.15-1.5 mg) was injected into the subarachnoid space of the ventral brain stem of exteriorized fetal sheep. Changes in pH on the ventral surface of the medulla did not stimulate respiratory efforts or induce significant cardiovascular changes. The respiratory response to DNP injections ranged from no response to prolonged rhythmic ventilation that was independent of the peripheral chemoreceptors or the control arterial pH and blood gas tensions. This inconsistency suggests an effector site somewhat removed from the immediate surface of the medulla. The heart rate and blood pressure were not affected. It is concluded that increased H+ concentration in the extracellular fluid of the fetal ventral medulla does not initiate respiration, and any respiratory response to metabolic inhibitors applied to this area therefore is not attributable to a secondary change in surface pH.     

Acute cerebral artery constriction in the spontaneously hypertensive rat following blood and plasma administration into the subarachnoid space

The purpose of the present study was to demonstrate, using a vascular casting technique, acute vasoconstrictive changes in the cerebral vasculature 1 h following whole-blood or plasma infusion into the subarachnoid space of conscious spontaneously hypertensive rats. Vascular casts from animals infused (over 20 min) with 0.45 ml of heparinized autologous arterial blood or plasma exhibited incomplete filling, while casts from saline-infused controls exhibited virtually no filling defects. Significant elevations in intracranial pressure were noted in blood, but not in plasma- or saline-infused rats. Two characteristic forms of constriction occurred, depending upon the vessel lumen diameter. Vessels with lumen diameters >100 µm were flattened longitudinally with deep endothelial nuclear imprints, while smaller vessels had focal circular constrictions resembling beads. Arterial cast filling terminated in vessels with lumen diameters from 70 to 20 µm with focal signs of constriction at or near the point of cast termination. The results indicate that the presence of both blood and plasma in the subarachnoid space produces acute small-artery constriction. This phenomenon is due to a noncellular blood component and does not correlate with increases in intracranial pressure.     

肾动脉内注射腺苷兴奋肾神经传入纤维的自发活动

应用记录肾神经传入纤维多单位和单位放电的方法,观察肾动脉内注射腺苷对麻醉家兔肾神经传入纤维自发放电活动的影响。结果表明：(1)肾动脉内注射50,100和200nmol／kg腺苷可呈剂量依赖性地兴奋肾神经传入纤维的活动,而动脉血压不变。(2)肾动脉内预先应用选择性腺苷A1受体阻断剂DPCPX(160nmol/kg),可部分阻断腺苷对肾神经传入纤维的兴奋作用。(3)静脉应用一氧化氮合酶抑制剂L-NAME(0．1mmol／kg)预处理,延长并增强了肾神经传入纤维对腺苷的反应。以上结果提示,肾动脉内应用腺苷可兴奋肾传入纤维的自发放电活动,一氧化氮作为抑制性因素参与腺苷诱导的肾神经传入纤维兴奋。