Biomedical subjects
Publications and source records attributed to R C Schaeffer.
The heterogeneity of separate Echis carinatus and Echis coloratus venom lots were evaluated by high performance size-exclusion chromatography, as well as by clotting and esterolytic activities. Each lot of E. carinatus and E. coloratus venoms appeared to be unique. The variation in E. carinatus venom activities from snakes within the same species could lead to contradictory biochemical and/or physiological test results.
We studied the effects of crystalloid (75 ml/kg of Ringer's lactate) or colloid (6% dextran-70, 6% hydroxyethyl starch, or 25 ml/kg of 5% human serum albumin) fluid infusions or no treatment (control) on the calculated lung capillary (Pc)-plasma oncotic pressure (pi c) gradient and pulmonary edema. Two sets of mongrel dogs were studied: uninjured (n = 25; 14 to 22 kg) and pulmonary fibrin-microembolized (n = 25; 15 to 23 kg). In both sets of experiments, left atrial pressure was controlled (15 mm Hg) throughout the 4-h plus experimental period. In the uninjured set, the Pc-pi c gradient averaged +1.0 and -0.2 mm Hg in the hydroxyethyl starch and dextran groups, +0.7 and +2.3 mm Hg in the human serum albumin and control groups, and +6.2 mm Hg in the Ringer's lactate group. In the fibrin-microembolized group, this gradient averaged 2.6, 2.4, 3.0, 5.3, and 9.5, respectively. The extravascular lung water to bloodless dry lung wet weight ratios in the no-fluid treatment group of the uninjured and microembolism groups with increased pressure (3.8 +/- 0.3 to 4.1 +/- 0.4 [SEM]; NS) are consistent with interstitial or perivascular edema. There were, however, no significant differences noted between the respective control groups or any fluid treatment group in either set of experiments. These data support the view that infusion of either colloid or crystalloid solutions in normal or pulmonary fibrin-microembolized lungs does not produce sufficient change in the Pc-pi c gradient to elevate edemagenesis when pulmonary capillary pressure is limited to 22 mm Hg in dogs.
A procedure is described for the preparation of fluorescein isothiocyanate-labeled hydroxyethyl starch (FITC-HES). Chromatographic techniques for the purification and analysis of FITC-HES that include the development of a high-performance size-exclusion chromatographic (HPSEC) technique with a fluorescence spectrophotometer-computer detection system are described. FITC-HES macromolecules have a wide range of hydrodynamic radii (ae greater than 120- less than 10 A) and the substitution ratio of FITC to the size-selected HES macromolecules remains constant throughout the chromatographic range. The predominant isoelectric point (pI) of the multiple acidic isomers of FITC-HES is 4.6. In vitro, the very large FITC-HES macromolecules (greater than 100 A) are rapidly degraded (15 sec) by alpha-amylase in control dog plasma. While most of the large molecules (100-20 A) remain intact for greater than 24 hr, this degradation is not associated with the loss of FITC from HES. In vivo, the rate of this reaction appeared to be accelerated and the degradation of FITC-HES between 0.1 and 12 hr was small. Illustration of the HPSEC quantitation of the spectrum of FITC-HES macromolecules in "near steady-state" lymph (L) and plasma (P) samples and the L/P ratio show that this technique can be used to describe the size selectivity of the blood-lymph barrier under conditions of unaltered capillary pressure. We propose that the size-selected solvent-drag reflection coefficient (sigma f) curves for the anionic FITC-HES under conditions of elevated capillary pressure is a measure of macromolecular convective permeability of the blood-lymph barrier.
Disseminated intravascular coagulation (DIC) was produced by an infusion of a prothrombin activator (Echis carinatus venom; 30 minutes; 0.5 NIH thrombin equivalent U/kg) in mongrel dogs (Echis group, n = 7). Fibrinogen declined to below measurable levels (less than 25 mg/dl), and fibrin-fibrinogen degradation products appeared (53 +/- 8 micrograms/ml) at end venom infusion in the Echis group. These alterations were not seen when an irreversible thrombin inhibitor, D-phenylalanyl-L-prolyl-L-arginine-L-chloromethyl ketone (PPACK) (57 nmol/kg/min for 120 minutes), was given alone (PPACK group, n = 5) or in association with venom (Echis + PPACK group, n = 5). Factor II activity (1% +/- 1%) in the Echis and Echis + PPACK groups was significantly below the PPACK (55% +/- 9%) and the control (79% +/- 2%) levels at 120 minutes. In contrast, factor VIII coagulant (factor VIII:C) activity in the Echis group (1% +/- 1%) remained significantly below that in the Echis + PPACK (68% +/- 8%), PPACK (78% +/- 10%), and control (91% +/- 9%) groups at this interval. No change in factors X (91% +/- 7% to 81% +/- 7%, P not significant) and VII (64% +/- 10% to 48% +/- 11%, P not significant) activities were observed. Hemolysis was observed only in the Echis group, whereas thrombocytopenia and leukopenia were noted in both the Echis and the Echis + PPACK groups. These data show that large amounts of E. carinatus venom produce rapid DIC in vivo, because of the activation of prothrombin. In contrast, the decline in factor VIII:C activity appeared to be the result of the liberated thrombin. PPACK antagonized all of the venom-released thrombin without any major deleterious clotting abnormalities. This inhibitor appears to prevent thrombin-mediated DIC in vivo. In contrast, heparin was found to be an unreliable antagonist of the venom-released thrombin in vitro. PPACK also inhibited the marked hemolysis usually observed after venom. In addition, we found that the esterolytic (N-benzoyl-L-prolyl-L-phenylalanyl-L-arginine-p-nitroanilide HCL) activity of E. carinatus venom degrades fibrinogen in vitro.
The circulatory, respiratory, metabolic, lethal and tissue permeability effects of an i.v. infusion (30 min; 1.5, 2.0, 2.5 and 3.0 mg/kg) of puff adder (Bitis arietans) venom were studied in Sprague-Dawley rats (n = 35, 275-325 g). Venom (2.5 mg/kg) produced circulatory failure with arterial hypotension, hemodilution, hypoproteinemia, lactacidemia and marked hyperventilation by +4 hr. In a separate test (n = 20, 282-325 g) blood volume was measured at end venom (2.5 mg/kg) infusion (0 time) and at +3 hr with radioiodinated (125I) human serum albumin and 51Cr-labeled rat red blood cells. Venom produced a significant reduction in total blood volume index (9%, P less than .05), plasma volume index (12%, P less than .01) and red cell mass index (6%, P = N.S.) as compared to the control group at 0 time. Critically low levels of these indices were observed (43, 42 and 46%, respectively) at +3 hr. At both intervals the transvascular escape rate of radioiodinated human serum albumin but not 51Cr-labeled rat red blood cells was significantly increased in comparison to the control group. Tissue permeability index to 51Cr-labeled rat red blood cells and radioiodinated human serum albumin was increased primarily in the stomach and small intestine. These data suggest that increased vascular permeability to protein and red cells, primarily in the splanchnic region, leads to hypovolemic shock and death after a lethal dose of i.v. Bitis venom in rats.
We produced pulmonary fibrin microembolism using an infusion of a prothrombin activator (Echis carinatus venom, 30 min, 0.5 NIH thrombin equivalent units/kg) in open-chest mongrel dogs. To determine the nonclotting effects of this venom on edemagenesis we infused an irreversible thrombin inhibitor, D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone (PPACK, 57 nmol X kg-1 X min-1 for 120 min), alone (n = 5) or with venom (Echis + PPACK, n = 5). The control group (n = 5) was given 1 ml of 0.9% NaCl. A decline in left atrial pressure (means +/- SE, 5.3 +/- 0.4 to 4.0 +/- 0.5 mmHg, P less than 0.05) and cardiac index (149 +/- 10 to 82 +/- 13 ml X min-1 X kg-1, P less than 0.01) in association with a marked increase in pulmonary arterial pressure (14.5 +/- 0.6 to 26.6 +/- 2.5 mmHg, P less than 0.001) and pulmonary vascular resistance (64 +/- 5 to 304 +/- 42 mmHg X ml-1 X min-1 X kg-1, P less than 0.001) was observed after 20 min of venom infusion. During this interval, pulmonary artery wedge pressure increased (4 +/- 1 to 12 +/- 4 mmHg, P less than 0.01) in four of eight animals. Fibrinogen declined below measurable levels and fibrin microemboli were seen in many pulmonary arterioles. These changes were not observed in the Echis + PPACK, PPACK, or control groups. Leukopenia and thrombocytopenia were observed in the Echis and Echis + PPACK groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Physiologic effects of colloidal (5% albumin, 6% hydroxyethylstarch, 6% dextran-70) and crystalloidal (Ringer's lactate) fluids were examined in rats (six in each fluid group) after infusion of an LD99 of rattlesnake venom, previously shown to produce shock secondary to increased vascular permeability. Venom infusion (iv, 2.0 mg/kg, 30 min) was followed by fluid infusion (iv, 30 min) in quantities sufficient to reverse venom-induced hemoconcentration. Venom infusion decreased mean arterial pressure, increased blood lactate, and increased hematocrit in all animals (p less than .01). Fluid infusion reversed these changes, although six times the volume of crystalloid was required to produce hemodilution comparable to the colloidal fluids (120 ml/kg Ringer's lactate, 20 ml/kg colloids). Although no significant changes in the respiratory parameters were noted after administration of the three colloids, Ringer's lactate produced decreases in PaC2 (107 +/- 6 torr, mean +/- SEM to 72 +/- 7, p less than .05), increases in PaCO2 (30 +/- 4 torr to 55 +/- 5, P less than .001), decreases in plasma colloid osmotic pressure (14.2 +/- 0.8 torr to 6.6 +/- 0.9, p less than .001) at the end of fluid infusion. These changes were associated with significantly increased wet-dry lung ratios (p less than .001) in identically prepared animals, sacrificed after fluid infusion. In spite of the development of pulmonary edema in the crystalloid-treated animals, survival was similar for each group (6/6 for albumin and dextran, 5/6 for hydroxyethylstarch and Ringer's lactate). We thus conclude that both colloidal and crystalloidal fluid resuscitation leads to survival in permeability shock. Resuscitation with crystalloidal fluid, however, requires significantly greater volumes and is associated with the development of pulmonary edema.
Hypotensive and hemostatic properties of Southern Pacific rattlesnake (Crotalus viridis helleri) venom (100 micrograms/kg; i.v. bolus) or venom fractions (40 micrograms/kg) were studied in mongrel dogs (n = 27, 15-27 kg). Venom was separated by gel filtration (Sephadex G-100) into three lethal fractions (FR I, II and III). Nonreduced crude venom contained 11 main protein bands on sodium dodecyl sulfate-10% polyacrylamide gel electrophoresis with a molecular weight range of 104 to 13 kD. FR I contained nine of these prominent bands (104-27 kD) and FR II contained five bands (34-13 kD). A 19-13 kD band comprised 92% of FR III. Crude venom rapidly produced hypotension, thrombocytopenia, hemolysis, the generation of fibrin monomers and a decrease in Factor VIIIC activity. Fibrin/fibrinogen degradation products appeared at +15 min and fibrinogen concentration was significantly depressed at +120 min. There was no significant change in prothrombin time or concentration of Factors VII, X and XII activity. However, the partial thromboplastin time was increased (P less than .05) by +30 min. Our data show that a high molecular weight thrombin-like venom component in FR I (greater than 27 kD) directly digests fibrinogen without activation of extrinsic and intrinsic coagulation factors. In addition, this fraction leads to the activation of the fibrinolytic system. It appears to be likely that the thrombocytopenia is primarily the result of ca. 27 kD platelet aggregating protein found in similar amounts in FR I and II. Venom components in FR II (ca. 34 and 29 kD,) were associated with hypotension and hemolysis.(ABSTRACT TRUNCATED AT 250 WORDS)
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Cardiovascular failure (shock) associated with acute alcohol ingestion and severe hypothermia (core temperature 23 and 21 degrees C) was studied in 2 patients. In each case, perfusion failure was associated with lactacidemia, severe bradycardia, and agonal respirations. Infusion of fluids and mechanical ventilation reversed shock and prevented a fatal outcome. One case, complicated by renal failure and volume overload with pulmonary edema, was managed with peritoneal dialysis. These findings suggest that perfusion failure associated with severe accidental hypothermia after acute alcohol ingestion is due to a combination of hypovolemia, bradycardia, and respiratory depression.
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Edema fluid and a coagulation profile were obtained in 45 patients (17 to 87 years) during fulminant pulmonary edema. Left ventricular failure and/or volume overload accounted for edema in 18 patients. In another 27 patients, edema developed in association with other features that typify the adult respiratory distress syndrome (ARDS). In the ARDS group, multiple disorders were implicated in the genesis of edema, including shock, bacteremia, drug overdose, and aspiration. Assessment of edema fluid and coagulation measurements is useful to classify and to determine the severity of the edema process. ARDS is characterized by permeability pulmonary edema that usually stems from a combination of multisystemic disorders. Permeability pulmonary edema and coagulation changes appear to be interrelated. However, it is not clear the extent to which the coagulation disturbances are a cause or a result of the alterations in the alveolar-capillary membrane.
A model of regional shock is described to study the dynamics of lactacidemia which accompanies perfusion failure. The suprarenal abdominal aorta was occluded with a balloon catheter to reduce the mean perfusion pressure to 25 mmHg in 5 dogs each for 60 and 120 minutes, while 5 dogs served as controls. Increases in arterial lactate from 2.4 r - 1.1 to 4.9 r - 1.2 mM/L were observed by 60 minutes. Lactate concentrations sampled from arterial and venous sites proximal and distal to the obstruction, showed good correlation (r=0.96) during and for 240 minutes following deflation of aortic balloon. Lactate clearance in experimental animals was accomplished by 90 minutes of re-establishment of flow to the lower extremities. Hemodynamic changes included tachycardia, upper body hypertension, with any increase in left ventricular filling pressures. Marked hemoconcentration observed in experimental animals was suggestive of plasma losses in splanchnic circulation, confirmed by autopsy findings of bowel edema and infraction, In this model of regional shock, absence of true lactate "washout" was also confirmed.
Hemostatic changes were observed in mongrel dogs (N = 5, 18.6 26.7 kg) following and i.v. LD20 (50 microgram/kg) of rattlesnake (Crotalus viridis helleri) venom. Venom produced thrombocytopenia within 5 min and fibrinogen was significantly reduced at 240 min. In addition, the presence of fibrin split products, a positive protamine sulfate test and a decrease in the euglobulin lysis time, suggest that fibrinogenolysis and fibrinolysis are initiated shortly after venom. Prothrombin and partial thromboplastin times were little affected. Examination of bone marrow revealed vacuolization and a reduction in the number of megakaryocytes. These data suggest that this dose of rattle-snake venom produces hemostatic defects by the destruction of fibrinogen and circulating platelets.
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Hemodynamic changes and samples of fluid from pulmonary edema were studied in a 50-year-old woman who developed florid pulmonary edema following intracranial hemorrhage. Marked systemic and pulmonary arterial hypertension were associated with the rapid production of edema fluid that contained red blood cells, but had a lower protein content than plasma. After restoration of pulmonary vascular pressures to a normal range, the production of fluid ceased, and clinical signs of edema resolved. These findings point to the sudden increase in pulmonary microvascular pressure as the cause of pulmonary edema in this patient. Our findings contrast with those of previous reports and with speculations on the extent of a defect in permeability accounting for pulmonary edema following injury to the brain.