Role of the adrenal cortex and sodium in the pathogenesis of human hypertension.

After 30 years of continuous research into the mechanisms of human hypertension, we summarize the results obtained by the members of the multidisciplinary research group on hypertension of the Clinical Research Institute of Montreal on the disturbances of minerlocorticoid activity in a rigorously selected group of patients with early, mild essential hypertension. We attempt to integrate these findings with those of many other groups working on other aspects of hypertensive cardiovascular diseases. On the assumption that the increased peripheral resistance responsible for hypertension results from an imbalance or a disturbance of the equilibrium between the sympathetic nervous system and norepinephrine on one hand, and the vascular tone, sensitivity and responsiveness of the arterial smooth muscle to norepinephrine and to angiotensin II on the other hand, three models that fit the experimental and clinical facts as known at present are described.     

Heidenhain's Hematoxylin Used with the Smear Technic

Heidenhain's hematoxylin, according to the following formula, may be used for studying chromosomes in temporary smears of pollen mother cells: 1 part 0.5% hematoxylin and 4% iron-alum (equal parts of each); 1 part 95% alcohol; and 2 parts glacial acetic acid.     

VACUUM DRYING OF STEAM STERILIZED DRESSINGS

SUMMARY: The degree of vacuum and time of application needed to dry steam sterilized dressings has been investigated. If the steam supply is dry, and the pressure in the drying stage is reduced to an absolute pressure of 50 mm Hg, dressings will be cool and dry without holding the vacuum, provided they are not damp before sterilization.     

Degradation of extracellular matrix proteins by hemorrhagic metalloproteinases

The proteolytic activity of four hemorrhagic metalloproteinases (Ht-a, c, d, and e) isolated from the venom of the Western diamondback rattlesnake (Crotalus atrox) was investigated using isolated extracellular matrix (ECM) proteins. We determined that all of the proteinases are capable of cleaving fibronectin, laminin, type IV collagen, nidogen (entactin), and gelatins. However, none of the proteinases were proteolytic against the interstitial collagen types I and III or type V collagen. With all of the substrates listed above Ht-c and Ht-d produced identical digestion patterns, as would be expected for these isoenzymes. With fibronectin, Ht-a produces a different ratio of products from Ht-c and Ht-d, while Ht-e produces a unique pattern of digestion. Ht-e and Ht-a produced nonidentical patterns with the laminin/nidogen preparation although some similarity was shared between them as well as with the Ht-c/d digestion pattern. Similar results were also observed for these proteinases with nidogen 150 as the substrate. The type IV collagen digestion patterns by Ht-e and Ht-a were similar to the pattern observed with Ht-c/d but differed by two bands. The digestion patterns of the three gelatins produced by the proteinases show differences between Ht-c and Ht-d when compared to Ht-e and Ht-a. This investigation clearly shows that several of the ECM proteins are efficiently digested by these toxins. The proteinases have some digestion sites in common but show differing specificities. In addition, the range of ECM proteins digested by these hemorrhagic proteinases is nearly identical to that demonstrated by the ECM proteinase stromelysin (MMP-3). From these data, and the knowledge of the roles these ECM proteins have in maintaining basement membrane structural/functional integrity, one can envision that the degradation of these ECM proteins could readily lead to loss of capillary integrity resulting in hemorrhage occurring at those sites.     

X-ray and magnetic resonance stereotaxy for functional and nonfunctional neurosurgery

By means of new plastic stereotactic ring and head fixers, stereotactic procedures can be combined with MRI, with stereotactic coordinates obtained from the MRI images. The method was rechecked against CT stereotaxy and shows a good correspondence of the target coordinates. With MRI stereotaxy, structures near bony regions will be more accessible than with CT stereotaxy. Moreover, the MRI procedure seems to have advantages for functional therapy without the necessity of contrast ventriculography.