Pericyte endothelial gap junctions in human cerebral capillaries

Human cerebral tissue has been ultrastructurally studied and gap junctions have been visualized between endothelial cells and pericytes that permit ion exchange. We propose that the functional interrelationship between endothelium and pericytes may play a role in the alteration of capillary diameter for the control of local cerebral blood flow.

Aspects of interastrocytic gap junctions in blood-brain barrier in the experimental penumbra area, revealed by transmission electron microscopy and freeze-fracture

Interastrocytic gap junctions in the blood-brain barrier of the experimental penumbra area were studied in the cat caudate nucleus 1 h after ischemia. Transmission electron microscopy and freeze-fracture studies revealed only slight changes in gap junctions between astrocytes, indicating that these junctions are very resistant to hypoxia.

Assemblies of intramembranous particles in astrocytoma: a preliminary report

A human astrocytoma has been studied with the freeze-fracture technique. The astrocytic membrane presents many assemblies formed by aggregations of intramembranous particles (5.8-7.8 nm in diameter) in P-face arranged in a square, and complementary pit assemblies in E-face. In the interastrocytic gap junctions the connexions are packed in a crystalline array.

Are the pores of intramembrane particles of postsynaptic membrane transmitter-dependent channels?

The rat neonatal cerebellar cortex has been studied using the freeze fracture technique. In the dendritic postsynaptic membrane, intramembrane particles containing an electron-dense central area have been detected. This type of area could be a platinum aggregate within a channel which, crossing the particle, may connect the postsynaptic cytoplasm with the synaptic cleft.

Smooth muscle cells in 'venous patches'grafted into the rat common carotid artery. A structural study

In the 2nd week after surgery, well differentiated smooth muscle cells (SMC) were evident in the walls of venous patches in rat common carotid artery. Gap junctions were the only type of intercellular junction observed between SMC in the present study.

Specific endothelial granules in venous patch neoendothelium in the rat

Weibel-Palade bodies were observed in the neoendothelium and capillaries of vasa vasorum of autologous 'venous patches' grafted in the common carotid artery of the rat. These corpuscles varied in number and distribution but were most frequently found in the luminal area of endothelial cytoplasm. In venous patch neoendothelium, the shape, size and substructure of Weibel-Palade bodies were similar to those in other types of vascular endothelium. These specific endothelial granules were more numerous during the week following neoendothelium formation. It is proposed that these corpuscles may play a role in the proliferation of endothelial cells in venous patches.

Intercellular junctions between smooth muscle cells in myointimal hyperplasia

Experimental intimal hyperplasia was obtained by microvascular surgery. A segment of the left common carotid artery of rat was grafted by means of end-to-end anastomosis onto the right common carotid artery of the same animal. 3 months after surgery, hyperplasia was observed in the intima of the grafted arterial segment formed by modified smooth muscle cells: myointimal cells. These cells do not present ultrastructural changes and they are connected by gap and tight junctions. The gap junctions are the predominant type of junction between myointimal cells in our experimental model.

Attraction of primordial germ cells by notochord in seven somites chick embryo

Chemical studies in chick embryo have indicated the existence of proteoglycan in notochordal sheath. Primordial germ cells were observed with scanning electron microscope on the notochord dorsal face, surrounded with perichordal material. We postulate the identification of such a material with proteoglycan which could attract primordial germ cells to the notochord.

[Evolution of the homotypic graft of the presumed cardiac area of the quail in the chick]

Employing quail cells as biological labelers, we could easily follow the evolution of the presumptive cardiac area of the quail in the chick blastoderm. If the embryos are operated on in stage 5, the cardiac area fuses completely to that of the host embryo forming a large part of the corresponding half in the definitive heart. On the other hand, in earlier stages the grafted cardiac area contributes only to the formation of island of cells in the resultant heart.

Septic lung and shock lung in man

Two series of patients were studied by serial measurements of blood gas exchange and pulmonarmonary dysfunction and to evaluate the dangers of respiratory failure in post traumatic patients. There were 27 patients who had sustained profound hemorrhagic shock and massive blood replacement averaging 9.7 liters and 38 patients who suffered general peritonitis or other forms of fulminating nonthoracic sepsis. All were supported by endotrachael intubation and volume controlled ventilators. The overall mortality for the post shock patients without sepsis was 12% while in the septic patients it was 35%. The maximal pulmonary arteriovenous shunt encountered in the post hemorrhagic shock patients at 36 hours averaged 20 plus or minus 8% and was accompanied by high cardiac indices (average 5.1 plus or minus 1.3 L/M-2/min) but no significant rise of pulmonary arterial pressure or peak inspiratory pressure (PIP). Severe pulmonary dysfunction subsequently occurred only in those patients who later became septic. The studies on the septic patients were divided according to the magnitude of the cardiac indices (the high indices averaged 4.8 plus or minus 1.6L/M-2/min) and thelow indices averaged 1.9 plus or minus 1.0 L/M-2/min. In the former, the average maximal shunt of 30 plus or minus 6% was sustained for 4 or more days, accompanied by an elevation of PIP to 36 plus or minus 6 cm H2O and by Pa pressure of 28 plus or minus 5 mm Hg. The patients in low output septic shock usually had an associated bronchopneumonia and had an average venous admixture of 34 plus or minus 8% and PIP values of 41 plus or minus 8 cm H2O. The mean Pa pressure in this group was 29 plus or minus 6 mm Hg.

Demonstration of a lethal endotoxemia of intestinal origin in refractory non-septic shock

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