THE MIGRATION OF LYMPHOCYTES ACROSS SPECIALIZED VASCULAR ENDOTHELIUM

The chain of lymph-nodes in the rat mesentery was isolated and the preparation was perfused via cannulae in the superior mesenteric vessels. The perfusate consisted of serum to which labelled lymphocytes had usually been added. The entry of radioactively labelled lymphocytes from the blood vessels into the lymph-nodes was studied by scintillation counting and autoradiography. It was observed that: (1) In the perfused node labelled lymphocytes localized in and around post-capillary venules in the paracortex as they do early after i.v. injection. (2) The number of lymphocytes which entered the node was directly proportional to the concentration in the perfusate over the range studied. The proportion of cells retained in the node varied considerably around a mean of 11 % of lymphocytes reaching it. (3) The isolated lymph-node released few if any lymphocytes into the effluent (venous) perfusate. (4) Large lymphocytes migrated into isolated lymph-nodes slightly more readily than did small lymphocytes. (5) Unlike intact cells isolated lymphocyte membranes did not adhere to specialized vascular endothelium.     

PASSAGE OF LIPID ACROSS VASCULAR ENDOTHELIUM IN NEWBORN RATS : An Electron Microscopic Study

An electron microscopic study of the fine blood vessels in the skin and muscle of 25 newborn rats (sucklings, and therefore subject to physiologic lipemia) has shown that blood-borne lipid particles may leave the lumen of these vessels by two pathways, intercellular and intracellular. (a) An intercellular pathway: Some capillaries, venous capillaries and venules contain intramural, extracellular deposits of lipid which is presumably hematogenous. In some animals these deposits are quite numerous; available evidence suggests that they are a consequence of intercellular gaps, too small or too transient to be observed except in rare instances. Plasma apparently escapes through these gaps and filters across the basement membrane, while lipid particles are retained, usually in sufficient number to fill the small defect; some lipid particles are then taken up by endothelial cells and pericytes, while a few escape and are incorporated into free phagocytes. These focal defects, though few in number, may explain the apparent incapacity of blood vessels of newborn rats to leak any further after a local injection of histamine. Discontinuities in the endothelium were found also in the renal glomerulus, sometimes accompanied by extensive interstitial accumulations of lipid particles. Similar intercellular gaps are known to exist in other types of immature endothelia. (b) An intracellular pathway: This is best demonstrated in the capillaries, venous capillaries and venules which supply the developing subcutaneous adipose tissue. Here the lipid particles adhere in large numbers to the endothelial surface; the morphologic evidence suggests that they are also taken up into the endothelium through phagocytosis by "flaps," or into pockets or crevices. The lipid is apparently metabolized in the vascular wall; some is found in the multivesicular bodies. There was no evidence of active transport by vesicles or vacuoles. Neither pathway was demonstrable in the adult.     

RAPTOR MIGRATION ACROSS THE STRAITS OF GIBRALTAR

The visible migration of birds of prey at Gibraltar is analysed from records kept throughout the spring passages of 1967–70 and the autumn passages of 1967–69. In early spring most visible passage is noted in the afternoons, whereas radar observations by Houghton (1970) indicate passage in the mornings. Later in the year an additional burst of visible passage sometimes occurs in the early morning, but it is concluded that most morning movements take place above visible range. Visible migration is recorded on most days of westerly wind during the migration seasons at Gibraltar. Passage is rarely seen when the winds are easterly. It is argued that under the latter conditions a strong upcurrent of air (standing wave) is formed over Gibraltar, and that this carries nearly all migrants above visible range.
Observations of visible passage elsewhere in the Straits suggest that, in spring, raptors of all species cross on a broad front from Tangier to Ceuta, except Honey Buzzards, which probably cross chiefly near Ceuta. In autumn, all species from northern Europe cross chiefly between Tarifa and to the east of Gibraltar, while birds from western Iberia probably cross mainly near Tarifa.
The periods of passage of the common migrant species are summarised.
On the basis of visual observations and published radar results, it is argued that raptors can compensate for lateral drift by the wind and so fly on chosen courses; but that in very strong cross-winds, e.g. the easterly Levanters, they may have to let themselves be drifted off-course.     

ESTIMATION OF THE MIGRATION OF THORACIC DUCT LYMPHOCYTES TO NON-LYMPHOID TISSUES

The distribution of radioisotopes in tissues was measured following i.v. injection of labelled thoracic duct lymphocytes into syngeneic rats. The rate of elution of an isotope from the labelled cells and the subsequent fate of the eluted isotope were shown to be the most important factors limiting the usefulness of such isotopes for measuring cell localization particularly in non-lymphoid tissues. Comparison of labelling procedures using [³H] and [¹⁴C]uridine, [³H] and [¹⁴C]leucine, [⁷⁵Se]-L-selenomethionine, [^99mTc]sodium pertechnetate and [⁵¹Cr]sodium chromate in vitro and [³H]thymidine in vivo showed that ⁵¹Cr had the fewest disadvantages in the present context. Using ^5ICr-labelled cells, the radioactivity was measured in a wide range of non-lymphoid tissues, and estimates of cell traffic were obtained. In skin, for example, the results indicate a cell flux in the range of 10⁴-10⁵ lymphocytes/gm/hr. Evidence is presented which suggests that the early substantial localization of labelled cells in the lung is not an artefact due to sequestration or embolization of traumatized cells but probably reflects a slow intravascular transit time through this capillary bed. The primary lymphoid organs, thymus and bone marrow were shown to include a subpopulation of lymphocytes which belong to the recirculating pool. The thymus always contained a greater concentration of radioactivity at 24 hr than all non-lymphoid tissues except liver and kidney (approx. 0-1% of the recirculating lymphocyte pool) and the bone marrow was capable of temporarily accepting a substantial proportion (approx. 25%) of the injected cells.     

MIGRATION ACROSS THE MEDITERRANEAN OBSERVED BY RADAR

Bird migration across the Mediterranean was studied by radar from an aircraft carrier for brief periods during the springs of 1961, 1962 and 1963 and in the autumn of 1963. The radar displays were photographed and analysed to give intensity (scales 0 to 6) and tracks have been plotted on the accompanying Maps together with Tables setting out the weather data and records of bird sightings. Most echoes that could be measured were between 4,000 and 6,000 ft. Small (passerine) echoes usually moved at 20–30 knots, large ones (presumed to be waders, ducks, etc.) at up to 47 knots. The analyses of each of the nine sets of observations are discussed in detail from the Atlantic to the south of Crete, including the Aegean. There is clear evidence, within the limitations of the stated methods used and the dates of observations, that migration takes place along the whole length of the Mediterranean at almost uniform density except across the Ionian Sea, where it is greatly reduced. This is possibly because the long desert crossing and the long sea crossing are separated by only a very narrow coastal strip of vegetation and there is obvious survival value in crossing further east or west. There is no evidence for concentration across the Sicilian narrows, through Malta or across the Straits of Gibraltar. The direction of migration west of the Ionian Sea is N.E./S.W. and to the east is N.N.W./S.S.E. A large-scale movement was observed coasting 20 miles offshore from Portugal in autumn tracking S.W. off Cape St. Vincent. This area in particular deserves further investigation as also does the area south of Crete. Migration is considerable at least from 18 August-24 October. The main departure of small migrants from land starts 40–50 minutes after sunset and tails off with the dawn. The diurnal pattern of intensity observed at sea is noted and it is suggested that the shape of the build-up and the time of the peak can provide a clue as to the point of departure. There are indications that in spring, especially south of Crete, some migrants do not rest in the narrow coastal strip but cross the Sahara Desert and the Mediterranean Sea non-stop. The significance of the results is discussed in the light of further visual observations made in 1964 and 1965.     

THE MIGRATION OF PASSERINE NIGHT MIGRANTS ACROSS THE ENGLISH CHANNEL STUDIED BY RADAR

An account is given of the migration of British summer resident small passerine night migrants across the English Channel in spring and autumn, as detected by radar.
The main times of passage of each species have been determined from the trapping records of Dungeness Bird Observatory.
The tracks of the migrants are consistent with the view that they always head about NNW in spring and SSE in autumn but may be drifted by a cross-wind.
The wind-direction and speed had a paramount influence on the volume of migration in both spring and autumn. Temperature had no effect in autumn, and though there was more migration with warmer than cold weather in spring, this need not have been due to the influence of temperature as such.
Small reversed movements occurred, with southerly winds in autumn or, more doubtfully, with northerly winds in spring.     

TEMPERATURE-INDUCED CAVITIES AND SPECIALIZED PARENCHYMA CELLS IN THE VASCULAR CYLINDER OF PEA ROOTS

Pea seeds (Pisum sativum L.) of six cultivars were planted in the field, in the greenhouse, or in growth chambers, in five different media, in light or dark, and at various temperatures (10–32 C). Under all conditions above 15 C the central portion of the vascular cylinder, in all cultivars except “Ageotropum,” tended to form cavities in almost every primary root examined. These cavities then became filled by the ingrowth of specialized parenchyma cells (SP cells). The formation of cavities and SP cells was temperature dependent since the roots grown below 15 C always formed central metaxylem tracheary elements (MTEs), without cavities and SP cells. Cavities and SP cells did not form over the entire root length. When the roots were longer than 3 cm, they started to form cavities and SP cells and continued for an additional 10–30 cm. After that, late MTEs formed in the central vascular cylinder, and no cavities and SP cells occurred regardless of temperature. Within an individual root grown above 15 C, cavities and SP cells tended to form during periods of fast growth, while during periods of slow growth large central MTEs formed instead.     

血管内皮细胞在氧自由基所致肺内动脉收缩反应中的作用

应用生物测定法观察黄嘌呤(X)-黄嘌呤氧化酶(XO)系统产生的氧自由基对正常、缺氧(5000m,10d)Wistar大鼠肺内动脉环张力的影响及内皮细胞在其中的作用。发现XO在一定浓度范围内产生的氧自由基可引起肺内动脉剂量依赖性收缩。正常鼠肺内动脉去内皮或加内皮舒张因子 (EDRF) 灭活剂后,此剂量依赖性收缩明显增强。慢性缺氧大鼠肺内动脉无论内皮完整与否,上述收缩反应均增强。提示缺氧使内皮细胞和(或)EDRF的功能受到损害。应用超氧化物歧化酶(铜锌SOD),在正常或缺氧鼠肺内动脉上可分别加强或恢复内皮细胞抑制氧自由基的缩血管作用。提示慢性缺氧时,内皮细胞和(或)EDRF受到超氧阴离子的严重破坏,这一机制可能在缺氧性肺动脉高压的形成中起重要作用。     

槲皮素对血管内皮细胞增殖和迁移的抑制作用

本实验研究了槲皮素对人脐静脉内皮细胞株(ECV304)增殖和迁移的抑制作用。研究发现,槲皮素作用一定的时间后,能明显抑制ECV304细胞的增殖(IC50为50．08μg/ml)和迁移(IC50为7．84μg／ml),而且其抑制作用呈浓度依赖性;细胞出现凋亡形态学改变,琼脂糖凝胶电泳形成DNA条带,推测其诱导细胞发生了凋亡。     

外源性CO对大鼠肺动脉平滑肌细胞迁移的影响

目的 :探讨外源性CO对大鼠肺动脉平滑肌细胞迁移的影响。方法 :体外培养大鼠肺动脉平滑肌细胞 ,用外源性CO处理 2 4h、48h、72h ,检测平滑肌细胞迁移情况。结果 :2 4h、48h、和 72h后未处理的对照组大鼠肺动脉平滑肌细胞迁移距离分别为 ( 332 16± 49 94)nm、( 44 2 83± 5 9 15 )nm和 ( 5 94.92± 6 2 .5 3)nm、后二者与 2 4h组比有显著差异 (P <0 .0 0 1)。 2 0、5 0、80 ppmCO处理细胞 2 4h后 ,细胞迁移距离分别为 ( 2 96 13± 5 5 32 )nm、( 2 47.87±5 8.2 3)nm和 ( 2 2 8 5 7± 72 6 8)nm ,除 2 0ppmCO组与对照组无显著差异 (P <0 .0 5 ) ,其余两组均显著低于对照组(P <0 .0 1)。 2 0、5 0、80 ppmCO处理细胞 48h、72h后 ,其迁移距离也显著低于对照组 (P <0 .0 1)。 结论 :大鼠肺动脉平滑肌细胞自身存在迁移情况 ,培养时间愈长 ,迁移距离愈大 ;外源性CO可以显著抑制平滑肌细胞的迁移 ,随着浓度增加 ,抑制作用增强     

MIGRATION OF SMALL LYMPHOCYTES IN ADULT MICE DEMONSTRATED BY PARABIOSIS

Parabiotic BALB/C mice were used to study the traffic of small lymphocytes in immunological mature but unchallenged mice. By giving ³H-thymidine (³H-TdR) injections to only one member (A) of a pair by preventing the escape of the radioactive isotope to the other member (B), the kinetics of newly-formed cells was followed. Less than 10% labelled small lymphocytes were found in the peripheral lymphoid tissues of both A and B members, while the thymusses and bone marrows of A members showed labelling percentages up to 70% in this period. Hardly any labelled cells gained entrance into the thymus while a detectable number was found in the bone marrows of B members. Results from pairs set up to follow migration of long-lived lymphocytes revealed that labelled cells detected 4–5 weeks after injections were equilibrated between the peripheral tissues and the bone marrows of the partners. Very few labelled cells were seen in the thymic medulla and none were observed in the thymic cortex, germinal centres or medullary cords of lymph nodes from any B member. It was concluded that short-lived small lymphocytes are formed primarily in the thymus and bone marrow and the migration of these cells is limited in adult animals. Furthermore, the vast majority of long-lived small lymphocytes are freely recirculating, and these cells gain entrance to and are normal residents in the bone marrow.     

反义CD151基因转染对大鼠血管平滑肌细胞迁移的影响

目的观察pcDNA3.1真核表达载体介导的反义CD151基因转染对培养的大鼠动脉平滑肌细胞(VSMCs)迁移的影响。方法构建携带全长正义和反义CD151的真核表达载体pcDNA3.1-CD151和pcDNA3.1-anti-CD151重组质粒,转染体外培养的VSMCs,以RT-PCR和Western blot方法检测CD151的表达,用Boyden趋化小室方法观察细胞迁移。结果与载体对照组、脂质体对照组和空白对照组3组均值比较,转染48h后,反义CD151组mRNA表达降低58%,蛋白表达降低51%,正义CD151组的VSMCs CD151mRNA表达增加171%,蛋白表达增加133%;趋化迁移的细胞数,反义CD151组为37.9±6.3,正义CD151组为86.5±12.4;载体对照组、脂质体对照组和空白对照组分别为60.3±7.1、61.8±7.6和67.3±9.6。反义CD151组显著低于其余各组(P<0.01),正义CD151组显著高于其余各组(P<0.01)。结论pcDNA3.1真核表达载体介导的反义CD151转染,通过抑制CD151的表达,能够显著抑制大鼠VSMCs的迁移。     

MORPHOMETRIC DATA ON THE ENDOTHELIUM OF BLOOD CAPILLARIES

Local differentiations within the endothelium of both muscular (diaphragm, myocardium) and visceral (pancreas, jejunal villi) capillaries have been studied in rats on sectioned and freeze-cleaved preparations. Four distinct parts have been recognized in the endothelial cells of all these vessels on the basis of subcellular components present in each part and on the basis of variations in the local frequency of plasmalemmal vesicles: (a) the parajunctional zone, (b) the peripheral zone, (c) the organelle region, and (d) the nuclear region. Our data indicate that ~16, ~7.0, and 8.5% of the endothelial cytoplasmic volume (in the peripheral zone) is accounted for by vesicles, their content, and their membranes, respectively. The average density of vesicular openings per µm² is 78 in diaphragm, 89 in myocardium, 25 in pancreas, and 10 in jejunal mucosa capillaries. The frequency of fenestrae is 1.7 times as high in jejunal (26/µm²) as in pancreatic capillaries (15/µm²), the corresponding fractional areas being ~9.5 and ~6%, respectively, of the endothelial surface. Intercellular spaces occupy a relatively small area (~0.08 to 0.2%) of the inner endothelial surface.