Administration of raw onion inhibits platelet-mediated thrombosis in dogs.

A number of studies suggest that dietary intake of onions is of benefit to cardiovascular health. Onion juice inhibits in vitro human platelet aggregation. To study the in vivo effect of onion on platelet aggregation, 11 dogs were prepared with mechanically damaged and stenosed coronary arteries. Periodic platelet-mediated thrombus formation followed by embolization produced cyclic flow reductions (CFR). In five dogs, 0.09 +/- 0.01 mL/kg onion juice administered intravenously abolished CFR within 20 min. This was followed by a 60 +/- 14% (P = 0.002) reduction in collagen-induced ex vivo whole-blood platelet aggregation. Six dogs were given 2.0 g/kg raw onion homogenate intragastrically. CFR were eliminated within 2.5-3 h in five of the dogs. This was accompanied by a 44 +/- 24% (P = 0.04) reduction in ex vivo aggregation. These findings suggest that the consumption of raw onion may help prevent platelet-mediated cardiovascular disorders. However, in vitro incubations of onion juice demonstrated that the platelet inhibitory response was significantly greater in dog blood than in human blood.

Mechanical strain induces specific changes in the synthesis and organization of proteoglycans by vascular smooth muscle cells.

In the mechanically active environment of the artery, cells sense mechanical stimuli and regulate extracellular matrix structure. In this study, we explored the changes in synthesis of proteoglycans by vascular smooth muscle cells in response to precisely controlled mechanical strains. Strain increased mRNA for versican (3.2-fold), biglycan (2.0-fold), and perlecan (2.0-fold), whereas decorin mRNA levels decreased to a third of control levels. Strain also increased versican, biglycan, and perlecan core proteins, with a concomitant decrease in decorin core protein. Deformation did not alter the hydrodynamic size of proteoglycans as evidenced by molecular sieve chromatography but increased sulfate incorporation in both chondroitin/dermatan sulfate proteoglycans and heparan sulfate proteoglycans (p < 0.05 for both). Using DNA microarrays, we also identified the gene for the hyaluronan-linking protein TSG6 as mechanically induced in smooth muscle cells. Northern analysis confirmed a 4.0-fold increase in steady state mRNA for TSG6 following deformation. Size exclusion chromatography under associative conditions showed that versican-hyaluronan aggregation was enhanced following deformation. These data demonstrate that mechanical deformation increases specific vascular smooth muscle cell proteoglycan synthesis and aggregation, indicating a highly coordinated extracellular matrix response to biomechanical stimulation.

Differential inhibition of human platelet aggregation by selected Allium thiosulfinates.

Thiosulfinates (TSs) have been implicated as a principle source of the antiplatelet property of raw onion and garlic juice. The in vitro responses of human platelets to dosages of four TSs were measured using whole blood aggregometry and compared by regression analysis. Of the compounds evaluated, methyl methane-TS (MMTS), propyl propane-TS (PPTS), and 2-propenyl 2-propene-TS (allicin) are present in freshly cut Allium vegetables, whereas ethyl ethane-TS (EETS) has not been detected. All TSs were synthesized using a model reaction system. PPTS and allicin had the strongest antiplatelet activity at 0.4 mM, inhibiting aggregation by 90 and 89%, respectively. At the same concentration, EETS and MMTS were significantly weaker, inhibiting 74 and 26%, respectively. Combinations of TSs were not additive in their inhibition of aggregation, indicating that the antiplatelet potential of Allium extracts cannot be easily predicted by quantifying organosulfur components. EETS, PPTS, and allicin were significantly more potent platelet inhibitors than aspirin at nearly equivalent concentrations.

Differential transmural distribution of gene expression for collagen types I and III proximal to aortic coarctation in the rabbit.

To assess the effects on the biosynthesis of collagen types I and III associated with an acute increase in blood pressure, we established a mid-thoracic aortic coarctation in the rabbit and studied gene expression and protein accumulation of these collagen types proximal to the stenosis 1, 3 and 7 days and 2, 4 and 8 weeks after coarctation. The mRNA level of type I collagen pro-alpha2(I) was maximal at 3 days and returned to normal at 4 weeks. mRNA of pro-alpha2(I) was localized mainly in the outer media, adventitia and intima. Accumulation of type I collagen and its precursors was increased by 3 days, peaked at 4 weeks, and decreased toward normal by 8 weeks, corresponding to the distribution of pro-alpha2(I) mRNA. Gene expression for pro-alpha1(III) was similar to that of pro-alpha2(I) but was distributed throughout the media. We conclude that the mechanical stresses associated with an acutely induced alteration in pressure initiate rapid gene expression for collagen types I and III in the aortic wall. The response for collagen type I, predominantly in the outer media and adventitia, suggests that these regions play an immediate role in the resistance to excessive dilatation of the aorta. The diffuse response for collagen type III in the media suggests participation in a more extensive remodeling response associated with the reinforcement and reorganization of the musculo-elastic fascicles.

Small mechanical strains selectively suppress matrix metalloproteinase-1 expression by human vascular smooth muscle cells.

Mechanical forces and biochemical stimuli may interact to regulate cellular responses. In this study, we tested the hypothesis that very small mechanical strains interact with growth factors in the regulation of matrix metalloproteinase (MMP)-1. Human vascular smooth muscle cells (VSMCs) were cultured on a precoated silicone membrane in a device that imposes a highly uniform biaxial strain. VSMCs cultured on fibronectin were treated with cyclic 1-Hz strains of 0, 1, or 4%, and MMPs were assayed by Western analysis or gelatin zymography. Small strains did not induce MMP-1 in VSMCs, but strain was a potent inhibitor of platelet-derived growth factor (PDGF)- or tumor necrosis factor-alpha-induced synthesis of MMP-1. In contrast, MMP-2 and TIMP-2 levels were not changed by PDGF and/or mechanical strain. VSMCs strained on the 120-kDa chymotryptic fragment of fibronectin or RGD peptides suppressed PDGF-induced expression of MMP-1, indicating that this effect is not mediated by the heparin-binding domain or connecting segment-1 of fibronectin. Northern analysis of ets-1, a transcriptional activator of MMP-1 expression, showed that strain down-regulated ets-1 expression, whereas c-fos expression was augmented. Thus, small deformations can selectively suppress MMP-1 synthesis by VSMCs, demonstrating the exquisite sensitivity of the cell to mechanical stimuli.

Mechanical deformation promotes secretion of IL-1 alpha and IL-1 receptor antagonist.

Both IL-1 alpha and IL-1 beta lack an N terminus secretory sequence, and the mechanism of secretion of these pleiotropic cytokines is incompletely understood. The epidermis contains large quantities of IL-1 alpha in keratinocytes, which may play a role in inducing endothelial adhesion molecules and promoting extravasation of leukocytes. Here we report that mechanical deformation of human keratinocytes leads to rapid release of IL-1 alpha, possibly through transient disruptions in the plasma membrane. Using a device that precisely controls the amplitude of strain on the culture substrate, we found by pulse-chase analysis, Western analysis, and ELISA that the release of IL-1 alpha is dependent on the amplitude of the strain. A cyclic strain of 14% released a small but significant quantity of IL-1 alpha, while strains of 33% released 66 +/- 9% of cytoplasmic IL-1 alpha over 1 h (p < 0.001). Release of IL-1 alpha was accompanied by rapid release of large stores of IL-1R antagonist, approximately 25 to 30 times greater by mass than the quantity of IL-1 alpha released, but only a small fraction of cytoplasmic lactate dehydrogenase. Media conditioned by mechanically stimulated keratinocytes induced expression of E-selectin by human vascular endothelial cells; induction of E-selectin was completely inhibited by an Ab to IL-1 alpha. Therefore, mechanical strain promotes the secretion of IL-1 alpha, and deformation of keratinocytes in the epidermis may activate vascular endothelium through mechanically released IL-1 alpha. This pathophysiologic mechanism may play a role in the anatomic localization of some inflammatory skin diseases, such as psoriasis, which occurs more commonly in locations where the dermis is subjected to repetitive stretch or trauma.

Mechanical strain tightly controls fibroblast growth factor-2 release from cultured human vascular smooth muscle cells.

Although fibroblast growth factor-2 (FGF-2) participates in the response to vascular injury, the role of cellular deformation in FGF-2 release is incompletely understood. To test the hypothesis that mechanical strain tightly controls FGF-2 release, a novel device was used to impose homogeneous and uniform biaxial strain to human vascular smooth muscle cells. Release of FGF-2 increased with the number of cycles of strain (14%, 1 Hz); 1, 9, and 90 cycles of strain, respectively, released 0.55 +/- 0.06%, 2.9 +/- 0.3%, and 5.5 +/- 1.3% of the total cellular FGF-2 (versus 0.00 +/- 0.40% for control, P < .05), but release was not further increased for strain of 90 to 90,000 cycles. Mechanical release of FGF-2 depended on both the frequency and amplitude of deformation. For example, strain (90 cycles, 1 Hz) at 4% amplitude released only 0.1 +/- 0.1% of the total FGF-2, but strain at 14% and 33% amplitudes, respectively, released 5.7 +/- 0.5% and 19.0 +/- 3.0% of the FGF-2 cellular pool (P < .05), suggesting a strain amplitude threshold for FGF-2 release. Injury to a subpopulation of cells increased with the frequency and amplitude of strain, but cells were not injured by strains below 10% amplitude. Strain following pretreatment with heparin released 12.6 +/- 1.6% of the total FGF-2 (versus 15.8 +/- 0.9% for strain alone, P < .05), indicating that most FGF-2 was liberated from the nuclear or cytoplasmic pools and not from low-affinity extracellular receptors. Conversely, strain in the presence of heparin released 25.2 +/- 3.5% of the total FGF-2 (versus 15.6 +/- 2.6% for strain alone, P < .05). Thus, cellular strain closely modulates the release of intracellular FGF-2 from human vascular smooth muscle cells, but FGF-2 release is negligible in response to the smaller strains that occur in the normal artery. In addition, larger mechanical strains lead to transfer of intracellular FGF-2 to the extracellular low-affinity receptors, where FGF-2 may be displaced by heparin. These observations provide insight into the mechanisms by which deforming vascular injury, such as that produced by arterial interventions, may elicit a proliferative response.

Acute epiglottitis in children.

Hemophilus influenzae type B (30 cases), untyped (two cases), and type A (one case), and H parainfluenzae (one case) were recovered in blood cultures from 44 cultures of 53 children with acute epiglottitis. These patients were managed by observation, tracheotomy, or intubation, with intubation being the most satisfactory. Both ampicillin and chloramphenicol have been employed recently because of the emergence of ampicillin resistance, which was 18.7% of all cases in 1977.

The diagnosis of CSF rhinorrhea by metrizamide CT scanning.

A case of cerebrospinal fluid rhinorrhea is presented in which routine diagnostic evaluation failed to disclose the site of leakage. Computerized tomography (CT) scanning with metrizamide, a nonionic contrast medium, provided not only documentation of the leak but also demonstrated the actual sinus involved. Metrizamide cisternography with CT scanning is a valuable technique in the evaluation of CSF rhinorrhea. It may only be used when an active leak is present. The patient described in this report lost several drops of CSF from the nose per minute in the face-down position. Neurotoxicity may be avoided by routine pre-examination medication with valium or phenobarbital. Mixing of the contrast agent with CSF is diminished by injecting in the subarachnoid space at C1-C2. The methods used in this examination and their indications are described, and the literature concerning metrizamide toxicity and pharmacologic properties reviewed.