Evidence for regulation of endothelial plasminogen-activating system by polymorphonuclear leukocyte elastase

Incubation of unstimulated polymorphonuclear leukocytes with cultured bovine pulmonary artery endothelial cells increased the activity of endothelial plasminogen activator. On the other hand, polymorphonuclear leukocytes stimulated by serum-opsonized zymosan decreased the plasminogen activator activity. A specific elastase inhibitor increased the enhancing effect of the unstimulated polymorphonuclear leukocytes and reversed the suppressing effect of the stimulated polymorphonuclear leukocytes. Catalytically active elastase suppressed the plasminogen activator activity and increased the activity of plasminogen activator inhibitor. In contrast, inactivated elastase enhanced the activity of plasminogen activator. Both, active and inactive forms of elastase bound to the endothelial cells. These findings suggest that elastase modulates the endothelial plasminogen-activating system, apparently by binding to the endothelial cells.     

Measurement of septal release of vasopressin and oxytocin by the push-pull technique following electrical stimulation of the paraventricular nucleus of rats

The release of vasopressin (AVP) and oxytocin (OXT) within the septum was studied with the push-pull perfusion technique in 6 conscious, freely behaving male rats. Push-pull perfusion was performed viaa chronically implanted cannula and samples collected for 3 consecutive 30-min periods. Stimulating electrodes were implanted in both the left and right paraventricular nuclei 4 days before the experiment. Bilateral electrical stimulation (10-s trains every 4 min) of the paraventricular nuclei during the second 30-min period resulted in a significant increase in the release of both AVP and OXT (128% and 159% of control values respectively); release returned to the pre-stimulation value during the final 30-min collection.     

Biomonitoring of aniline and nitrobenzene

Covalent binding to hemoglobin was studied to further substantiate the proposal that it may be used for biomonitoring N-substituted aryl compounds. (¹⁴C)-Labeled acetanilide and nitrobenzene were orally administered to female Wistar rats and binding indices [Binding(mmol/mol Hb)/Dose(mmol/kg)] determined; these were 12±1 and 73±10, respectively. After mild acidic or alkaline hydrolysis, 90% of the bound material was released and identified as aniline by radio thin layer chromatography. This supports the hypothesis that nitroso aryl derivatives, common intermediates in the metabolism of N-substituted aryl compounds, react with SH-groups of hemoglobin to yield sulfinic acid amides. Aniline was furthermore identified and quantified by capillary gas chromatography, using hemoglobin from animals treated with unlabeled aniline and nitrobenzene. Binding indices in this case were 30±3 and 85±19, respectively. With this method human blood samples may also be analysed.Although nitrobenzene is known to produce less methemoglobin than aniline, hemoglobin binding is higher. This indicates that hemoglobin binding may be a better index of body burden than methemoglobin levels in biomonitoring N-substituted aryl compounds.     

Platelet adhesion to smooth and rough hydrophobia and hydrophilic surfaces under conditions of static exposure and laminar flow

Platelet adhesion was measured on well-defined smooth surfaces and on the same surfaces with a known amount of roughness, under static conditions and in a new flow cell producing laminar flow. The results obtained with pig platelet suspensions show that under static conditions surface roughness does not influence platelet adhesion. With the flow cell an effect of roughness could be demonstrated, both with pig platelet suspension and with fresh canine blood: platelet adhesion decreased on a rough hydrophilic surface (glass) when compared with the same smooth surface, and increased on a rough hydrophobic surface (silane) when compared with the same smooth surface at the flow rates studied.     

Cortisol deficiency in metomidate anesthetized bacteremic pigs: results in circulatory failure — beneficial effect of cortisol substitution

Etomidate and the closely related metomidate are known to inhibit cortisol synthesis. We studied the influence of metomidate on hemodynamic performance and survival time of bacteremic pigs. Thirty pigs, 30.2 +/- 0.8 kg, were anesthetized with intravenous metomidate (2.5 mg.kg-1.h-1) plus ketamine (3.0 mg.kg-1.h-1), and were then mechanically ventilated. The animals were randomly allocated to three groups of 10 pigs each. Group A received an infusion of live Pseudomonas aeruginosa bacteria (2.5.10(9).kg-1.h-1 organisms until death), Group B additionally received a bolus of 1 mg.kg-1 cortisol (followed by an infusion of 0.1 mg.kg-1.h-1) starting 1 h prior to the bacterial infusion, and Group C served as anesthesia control without receiving bacteria or cortisol. The experiments in Group C were terminated after 10 h. In Group A the cortisol level was severely suppressed from the very beginning. The animals died of circulatory failure after 4.3 +/- 0.4 h. In contrast, Group B exhibited fairly stable hemodynamics, but the animals died due to pulmonary edema after 11.1 +/- 1.3 h. Cortisol deficiency in metomidate anesthetized pigs facilitates the development of circulatory failure in the course of Pseudomonas bacteremia, which does not occur if cortisol is infused to reconstitute a physiological level. However, this cortisol substitution did not prevent the development of pulmonary edema caused by Pseudomonas aeruginosa. Possible mechanisms of the deleterious effect of cortisol deficiency and implications in regard to the clinical use of metomidate/etomidate are discussed.     

The rate of Wallerian degeneration in the absence of immunoglobulins. A study in chick and mouse peripheral nerve

Sciatic nerves undergoing Wallerian degeneration are subject to massive invasion by monocytes bearing Fc receptors. The present experiments were done to explore the potential role of the Fc receptors. The effect of suppressed immunoglobulin levels on the rate of Wallerian degeneration was studied in the n. medioulnaris of the chick and in murine sciatic nerve. In the avian model, total immunoglobulin production was eliminated by bursectomy. The mice were injected after birth with antibodies against IgM, causing a selective reduction of immunoglobulin M levels. Myelin degeneration was measured in both groups by computer-assisted line sampling and corrected for intrafascicular edema. In both models, there were only minor differences with the controls. Immunoglobulins, accordingly, do not seem to play a significant role in the efficiency of myelin phagocytosis by monocytes during Wallerian degeneration. The study also includes data on the degree and the distribution of edema in nerves undergoing Wallerian degeneration.     

Improved intrinsic resolution: does it make a difference? Concise communication

The purpose of this study was to determine what effect further improvement in an Anger camera's intrinsic resolution has on lesion detection. We studied 52 patients undergoing bone imaging and 58 undergoing liver imaging. All patients had images performed in rapid sequence on ZLC -75 and ZLC -37 Anger cameras, both by Siemens. The two imaging systems are virtually identical except for the number of photomultiplier tubes and crystal thickness; these resulted in differences in intrinsic resolution ( ZLC -75 less than 3.8 mm FWHM at 140 keV, ZLC -37 less than 4.9 mm) and sensitivity ( ZLC -75 approximately 0.91 of ZLC -37 at 140 keV). Observer performance, measured by ROC curves, for detection of abnormalities was virtually identical with the two instruments. Subjectively, there was a trend toward preference of the ZLC -75 images, but this was not associated with any significant improvement in lesion detectability even in the subgroup in which a preference for one or the other instrument was noted.