Cultured endothelial cells produce heparinlike inhibitor of smooth muscle cell growth

Using cultured cells from bovine and rat aortas, we have examined the possibility that endothelial cells might regulate the growth of vascular smooth muscle cells. Conditioned medium from confluent bovine aortic endothelial cells inhibited the proliferation of growth-arrested smooth muscle cells. Conditioned medium from exponential endothelial cells, and from exponential or confluent smooth muscle cells and fibroblasts, did not inhibit smooth muscle cell growth. Conditioned medium from confluent endothelial cells did not inhibit the growth of endothelial cells or fibroblasts. In addition to the apparent specificity of both the producer and target cell, the inhibitory activity was heat stable and not affected by proteases. It was sensitive flavobacterium heparinase but not to hyaluronidase or chondroitin sulfate ABC lyase. It thus appears to be a heparinlike substance. Two other lines of evidence support this conclusion. First, a crude isolate of glycosaminoglycans (TCA-soluble, ethanol-precipitable material) from endothelial cell-conditioned medium reconstituted in 20 percent serum inhibited smooth muscle cell growth; glycosaminoglycans isolated from unconditioned medium (i.e., 0.4 percent serum) had no effect on smooth muscle cell growth. No inhibition was seen if the glycosaminoglycan preparation was treated with heparinase. Second, exogenous heparin, heparin sulfate, chondroitin sulfate B (dermatan sulfate), chondroitin sulfate ABC, and hyaluronic acid were added to 20 percent serum and tested for their ability to inhibit smooth muscle cell growth. Heparin inhibited growth at concentrations as low as 10 ng/ml. Other glycosaminoglycans had no effect at doses up to 10 μg/ml. Anticoagulant and non- anticoagulant heparin were equally effective at inhibiting smooth muscle cell growth, as they were in vivo following endothelial injury (Clowes and Karnovsk. Nature (Lond.). 265:625-626, 1977; Guyton et al. Circ. Res. 46:625-634, 1980), and in vitro following exposure of smooth muscle cells to platelet extract (Hoover et al. Circ. Res. 47:578-583, 1980). We suggest that vascular endothelial cells may secrete a heparinlike substance in vivo which may regulate the growth of underlying smooth muscle cells.     

Measuring opening pressure in lumbar puncture--a new method]

Determination of the opening pressure (OP) during diagnostic lumbar puncture (LP) yields additional information that may impact on treatment and prognosis in disorders affecting the central nervous system (e.g. meningitis). Established methods contain systematic errors as well as risks to the patient. We therefore present a new procedure that allows measurement of the OP by timing the flow of cerebrospinal fluid through a capillary attached to an LP needle. A resistance located between needle and capillary slows down the flow of cerebrospinal fluid so that it becomes independent of the capillary forces acting on it. The time required for the fluid to travel between two marks on the capillary (defining a given volume) can be used to calculate the flow. Since the combined resistance of needle and resistance can be calibrated, the pressure driving the flow--in this case the opening pressure--can be calculated. A simple model was used to evaluate the impact of different resistances and different needles on OP determination. The effects of cellular elements and proteins in the CSF are discussed.     

Biochemical evidence for the presence of arginine decarboxylase activity in Trypanosoma cruzi.

Trypanosoma cruzi was found to release 14CO2 from radiolabeled arginine, and this effect was inhibited by either DL-alpha-difluoromethylarginine or monofluoromethylagmatine, both specific inhibitors of arginine decarboxylase (ADC). Furthermore, agmatine, which can be derived metabolically only by ADC-mediated arginine decarboxylation, was produced when T. cruzi was incubated with radiolabeled arginine, and agmatine production was inhibited in the presence of DL-alpha-difluoromethylarginine. These results constitute direct biochemical evidence for the presence in T. cruzi of ADC, an enzyme that does not occur in mammalian cells.     

Metric studies of the dermal ridges of the palm in relation to handedness

Palm prints of 394 right-handers and 356 non-right-handers (left-handers and ambidexters) were evaluated regarding distance ad, ulnar shift, and relative horizontal triradius distance. Comparison between handedness groups produced some significant differences. The "graded distinction of dermatoglyphic traits" which was found in an earlier study has been confirmed. It has been suggested a modification of terminology for the position of axial triradii.     

Substructure of the glomerular slit diaphragm in freeze-fractured normal rat kidney

In the renal glomerulus, the narrow slits between adjacent epithelial podocytes are bridged by a diaphragm (2, 8, 11). In rat and mouse kidneys fixed by perfusion with tannic acid and glutaraldehyde (TAG), it has recently been discovered that this diaphragm has a highly ordered, isoporous substructure (9). It consists of a regular array of alternating cross bridges extending from the podocyte plasma membranes to a centrally running filament. This zipperlike pattern results in two rows of rectangular pores, approximately 40 X 140 A in cross section, dimensions consistent with the proposed role of the diaphragm as an important filtration barrier to plasma proteins (6). In the present study, we found in freeze-cleaved and in freeze-etched normal rat glomeruli that the surface of the slit diaphragm has an appearance conforming to the pattern found in sectioned material.     

Use of silica to identify host mechanisms involved in suppression of established Friend virus leukemia.

Silica, an agent predominantly toxic for macrophages, inoculated i.v. to Friend leukemia virus (FLV)-infected mice, blocks the FLV-leukemosuppressive effects of chlorite-oxidized oxyamylose (COAM)-statolon treatment. FLV-infected, COAM-statolon-treated mice that have received silica and have failed to suppress FLV leukemia produced normal amounts of interferon, but did not make antibodies cytotoxic for FLV leukemic cells. Transfer of untreated spleen cells, splenic T cells, or thymocytes from mice with suppressed FLV erythroleukemia to FLV-infected mice treated with silica and COAM-statolon restores the humoral immune response to FLV antigens and results in leukemosuppression. Thus, T lymphocytes from mice with suppressed erythroleukemia participate in FLV leukemosuppression either directly as effector cells, or indirectly as helper cell in the production of antibodies to FLV antigens.