Impact of Angiotensin II Antagonism on the Sex-Selective Dysregulation of Cardiovascular Function Induced by In Utero Dexamethasone Exposure

In utero exposure to glucocorticoids in late gestation programs changes in cardiovascular function. The objective of this study was to determine the degree to which angiotensin II mediates sex-biased changes in autonomic function as well as basal and stress-responsive cardiovascular function following in utero glucocorticoid exposure. Pregnant rats were administered the synthetic glucocorticoid dexamethasone (DEX 0.4mg/kg per day, s.c.) or vehicle on gestation days 18-21. Mean arterial pressure, heart rate, and heart rate variability (HRV) were measured via radiotelemetry in freely moving, conscious adult rats. To evaluate the impact of stress, rats were placed in a restraint tube for 20 minutes. In a separate cohort of rats, restraint stress was performed before and after chronic treatment with the angiotensin type 1 receptor antagonist, losartan (30mg/kg per day, i.p). Frequency domain analysis of HRV was evaluated, and data integrated into low frequency (LF: 0.20-0.75Hz) and high frequency (HF: 0.75-2.00Hz) bands. Prenatal DEX resulted in an exaggerated pressor and heart rate response to restraint in female offspring that was attenuated by prior losartan treatment. HF power was higher in vehicle-exposed female rats, compared to DEX females. Following losartan, HF power was equivalent between female vehicle and DEX-exposed rats. In utero exposure to DEX produced female-biased alterations in stress-responsive cardiovascular function which may be indicative of a reduction in parasympathetic activity. Moreover, these findings suggest this autonomic dysregulation may be mediated in part by long-term changes in renin-angiotensin signaling.

Anesthetic Management for Paraesophageal Hernia Repair

Paraesophageal hernia repairs are complex surgical cases frequently performed on patients of advanced age with multiple comorbidities, both of which create difficulties in the anesthetic management. Preoperative evaluation is challenging because of overlapping cardiopulmonary symptoms. The patient's symptoms and anatomy lead to an increased aspiration risk and the potential need for a rapid sequence induction. Depending on the surgical approach, lung isolation may be required. Communication with the surgeon is vital throughout the case, especially when placing gastric tube and bougies. Multimodal analgesia should include regional and/or neuraxial techniques, in addition to the standard intravenous and oral pain medications.

Elevation of an Amalgam-stained Margin With Resin-modified Glass Ionomer to Support an Indirect Ceramic Restoration: A Six-year Case Report

This case report presents treatment of a mandibular second molar with an extensive proximal margin, which was finished on amalgam-stained dentin. A resin-modified glass ionomer for margin elevation and a lithium disilicate onlay were used to restore the tooth to proper form and function. The patient has been followed for six years and has had no complications during this period.

Gene Therapy of the Peripheral Nervous System: Celiac Ganglia

Gene therapy has played an integral role in advancing our understanding of the central nervous system. However, gene therapy techniques have yet to be widely utilized in the peripheral nervous system. Critical targets for gene therapy within the PNS are the neurons in sympathetic ganglia, which are the final pathway to end organs. Thus they are the most specific targets for organ-specific neuron modification. This presents challenges because neurons are not viscerotopically organized within the ganglia and therefore cannot be targeted by their location. However, organ-specific neurons have been identified in sympathetic ganglia of some species and this offers an opportunity for targeting and transducing neurons by way of their target. In fact, alterations in sympathetic neurons have had pathological effects, and transducing organ-specific sympathetic neurons offer an exciting opportunity to selectively modify sympathetic pathology. In this chapter, we describe a method to virally transduce the celiac ganglion (CG), a prevertebral sympathetic ganglion that innervates abdominal organs, with AAV serotypes 1 and 6; thereby, providing a potential avenue to modulate specific subsets of neurons within the celiac ganglion.

Results of a 90-day safety assurance study with rats fed grain from corn rootworm-protected corn

The results of a 90-day rat feeding study with YieldGard (YieldGard Rootworm Corn is a registered trademark of Monsanto Technology, LLC.) Rootworm corn (MON 863) grain that is protected against feeding damage caused by corn rootworm larvae are presented. Corn rootworm-protection was accomplished through the introduction of a cry3Bb1 coding sequence into the corn genome for in planta production of a modified Cry3Bb1 protein from Bacillus thuringiensis. Grain from MON 863 and its near isogenic control were separately formulated into rodent diets at levels of 11% and 33% (w/w) by Purina Mills, Inc. Additionally, six groups of rats were fed diets containing grain from different conventional (non-biotechnology-derived) reference varieties. The responses of rats fed diets containing MON 863 were compared to those of rats fed grain from conventional corn varieties. All diets were nutritionally balanced and conformed to Purina Mills, Inc. specifications for Certified LabDiet 5002. There were a total of 400 rats in the study divided into 10 groups of 20 rats/sex/group. Overall health, body weight gain, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, gross and microscopic appearance of tissues were comparable between groups fed diets containing MON 863 and conventional corn varieties. This study complements extensive agronomic, compositional and farm animal feeding studies with MON 863 grain, confirming that it is as safe and nutritious as existing conventional corn varieties.

Role of pancreatic duct stenting in the treatment of chronic pancreatitis

BACKGROUND

Endoscopic retrograde cholangiopancreatography and stent placement are relatively new alternatives to surgery for the treatment of chronic pancreatitis. The objective of this study was to determine the efficacy of pancreatic duct stent placement for the treatment of chronic pancreatitis.

METHODS

This study included 89 patients treated with pancreatic stents between 1993 and 2002. The patients were contacted via telephone for a personal interview with regard to pain, medication usage, weight loss or gain, and eating patterns. Additionally, medication usage before and after treatment was documented from the Kentucky Cabinet for Health Services' electronic reporting system for narcotic use.

RESULTS

Of the 89 patients, 9 were deceased, 5 either refused to interview or could not be contacted, and 75 were interviewed. Significant weight gain exceeding 15 lb after treatment was experienced by 22%, whereas only 4% lost weight. A majority of the patients (68%) noted that they had less severe relapses or no relapses after treatment. The patients reported a decrease in pain level on a 10-point scale from 8.7 to 4.1 (53% decrease) after treatment. A decrease in pain medication usage was reported by 47% of the patients, and 83% considered their treatment successful. The Kentucky All Schedule Prescription Electronic Report (KASPER) was obtained before and after treatment for 55 patients. According to this statewide electronic reporting system, 63% had a documented decrease in narcotic use.

CONCLUSION

The findings of this study support the use of pancreatic duct stenting as an option before surgical intervention for these difficult-to-manage patients with chronic pancreatitis.

Results of a 13 week safety assurance study with rats fed grain from glyphosate tolerant corn

The current study presents the results of a 13 week feeding study in rats with grain from Roundup Ready corn which is tolerant to the herbicide glyphosate. Herbicide tolerance was accomplished through the introduction of cp4 epsps coding sequences into the corn genome for in planta production of CP4 EPSPS enzymes. Unlike related corn EPSPS enzymes, CP4 EPSPS enzymes are not inhibited by the herbicide glyphosate. Purina TestDiets formulated Roundup Ready corn grain into rodent diets at levels of 11 and 33% (w/w). The responses of rats fed diets containing Roundup Ready corn grain were compared to that of rats fed diets containing non-transgenic grain (controls). All diets were nutritionally balanced and conformed to Purina Mills, Inc. specifications for Certified LabDiet 5002. There were 400 rats in the study divided into 10 groups of 20 rats/sex/group. Overall health, body weight, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, gross and microscopic appearance of tissues were comparable between groups fed diets containing Roundup Ready and control corn grain. This study complements extensive agronomic, compositional and farm animal feeding studies with Roundup Ready corn grain, confirming it is as safe and nutritious as existing commercial corn hybrids.

204THE PRODUCTION OF INTRACYTOPLASMIC SPERM INJECTION LION (PANTHERA LEO) EMBYROS USING SPERMATOZOA COLLECTED BY PERCUTANEOUS EPIDIDYMAL SPERM ASPIRATION FROM VASECTOMIZED MALES

Contraception and/or sterilization methods have become an essential component of many captive animal management programs. Sterilization techniques are considered to be the last resort if a viable contraceptive cannot be attained and are generally not considered reversible. The African lion (Panthera leo) is one species in which sterilization techniques have been routinely applied. The objective of this study was to develop and evaluate a method for the collection of spermatozoa from male lions that have been previously rendered sterile by vasectomy. Percutaneous epididymal sperm aspiration (PESA) is a technique in which spermatozoa are aspirated from the epididymis and no surgical incision is required. In the present study, two lions (12 and 19 yrs old) were anesthetized and PESA was attempted. A 21-gauge needle attached to a 10-mL syringe (Norm-Ject) filled with 2–3mL of Tyrodes HEPES medium was gently inserted into the head of the epididymis and aspirated gently until spermatozoa were noted. Spermatozoa were visually assessed for motility (grade 1–5; 1=few motile sperm to 5=all motile), sperm concentrations were determined and then the sperm were cryopreserved. The total sperm concentration collected from the older (19yr) male was lower than that obtained from the younger (12yr) lion (0.08×106sperm/mL v. 65.5×106sperm/mL, respectively). Furthermore, more motile spermatozoa (grade 3) were collected from the younger individual compared to the older male (grade 1). Sperm samples from the 12-yr-old lion were frozen by multi-step addition of TEST yolk buffer+glycerol. Lionesses (n=3) were subjected to laparoscopic oocyte retrieval after gonadotropin treatment. A total of 38 oocytes were retrieved and 74% (28/38) were mature as determined by extrusion of the first polar body. Mature oocytes were subjected to ICSI using frozen-thawed spermatozoa obtained by PESA. More than 60% (17/28) of the injected oocytes cleaved and 100% (17/17) reached the morula stage by Day 5 or 6 of IVC. Embryos were cryopreserved and were subsequently transferred (n=15) into one lioness. We have demonstrated that it is possible to collect viable spermatozoa from sterile male lions using the PESA technique. Spermatozoa collected were motile and could be cryopreserved and functional for assisted reproductive techniques. This technique could be applied to other infertile or sterile males whose genetic background would benefit a current conservation program.

The identification of a potent, water soluble inhibitor of lipoprotein-associated phospholipase A2

Modification of the pyrimidone 5-substituent in a series of 1-((amidolinked)-alkyl)-pyrimidones, lipophilic inhibitors of lipoprotein-associated phospholipase A2, has given inhibitors of nanomolar potency and improved physicochemical properties. Compound 23 was identified as a potent, highly water soluble. CNS penetrant inhibitor suitable for intravenous administration.

Effect of hand sanitizer use on elementary school absenteeism

BACKGROUND

Several studies have indicated a connection between handwashing and illness-related absenteeism in school settings. The difficulty of ensuring consistent and effective handwashing among student populations has also been noted. The purpose of this study was to assess the effectiveness of the use of an alcohol gel hand sanitizer in the classroom to help decrease the illness-related absentee rate for elementary school students.

METHODS

This study involved 5 individual school districts, 16 individual schools, and more than 6000 students in Delaware, Ohio, Tennessee, and California. Individual schools in each district were paired into product and control groups. In the product group schools, an alcohol gel hand sanitizer was used by the students and staff when entering and leaving the classroom. Absenteeism due to infection was recorded, and the data were statistically analyzed.

RESULTS

The overall reduction in absenteeism due to infection in the schools included in this study was 19.8% for schools that used an alcohol gel hand sanitizer compared with the control schools (P <.05). Data from the school system with the largest teacher population (n = 246) showed that teacher absenteeism decreased 10.1% (trend) in the schools where sanitizer was used.

CONCLUSION

Elementary school absenteeism due to infection is significantly reduced when an alcohol gel hand sanitizer is used in the classroom as part of a hand hygiene program.

A prospective European Organization for Research and Treatment of Cancer Genitourinary Group randomized trial comparing transurethral resection followed by a single intravesical instillation of epirubicin or water in single stage Ta, T1 papillary carcinoma of the bladder

A total of 431 eligible patients with solitary, primary or recurrent stages Ta and T1 transitional cell carcinoma of the bladder was included in a randomized multicenter trial to compare a single intravesical instillation of 80 mg. epirubicin with water given immediately after resection, with respect to the disease-free interval and recurrence rate. The interval to initial recurrence was significantly better in favor of the epirubicin group. After a mean followup of 2 years it became evident that the recurrence rate after a single epirubicin instillation was decreased by nearly half with the same trend being found in all subgroups examined. Toxicity was mainly restricted to bladder irritation in plus or minus 10% of the cases. Pathology review brought considerable changes in T category from stages T1 to Ta (53%). Changes in grade were less pronounced but nevertheless important.

Acute effects of ethanol on hepatic endocytosis and processing of insulin in perfused rat liver

This study utilizes the perfused rat liver combined with subcellular fractionation and compartmental analysis to investigate the effects of ethanol on hepatic uptake, endocytosis, and processing of insulin. At 4 min after the start of a 2-min pulse of radiolabeled insulin, increasing ethanol concentrations progressively inhibited insulin uptake by the liver (57% at 50 mM ethanol). Subcellular fractionation of the perfused livers showed a progressive shift in distribution from a predominantly endosomal location (control) to a bimodal distribution between endosomes and plasma membrane. This could be largely accounted for by a specific reduction in the endosome-associated insulin. Binding studies showed no changes in the binding properties of the plasma membrane insulin receptor. Compartmental analysis of the perfusate efflux curves confirmed the lack of effect of ethanol on the binding constants but showed a significant decrease in the endocytic rate constant (50%) together with an increase in the retroendocytic rate constant (33%). Simulation studies with the compartmental model showed that these changes could account for the observed decrease in uptake by the liver. No changes were found in the subsequent endocytic degradation of insulin.

A plea for cold biopsy, fulguration and immediate bladder instillation with Epirubicin in small superficial bladder tumors. Data from the EORTC GU Group Study 30863

The sensitivity of cystoscopy to distinguish infiltrating from superficial bladder tumors is very high. Only 28 (5.6%) of 501 single tumors, which were considered to be superficial by the urologist at visual inspection, were found to be infiltrating on pathological examination. If the size of the tumor and/or the cytological grade are considered, one can further reduce the number of infiltrating tumors missed, but it was impossible to identify them all. The recurrence rate of tumors at the resection site 4 weeks after TUR suggests the importance of trauma of the bladder mucosa in promoting recurrence. A single instillation of Epirubicin immediately after TUR prevents implantation of tumor cells and reduces the recurrence rate to nearly 50%. A combination of cold forceps biopsy and fulguration may be the most reasonable treatment for small bladder tumors.

The use of targeting criteria in hospitalized HMO patients: results from the demonstration phase of the Hospitalized Older Persons Evaluation (HOPE) Study

OBJECTIVE

To determine the yield of standardized targeting criteria for identifying hospitalized HMO patients who are at high risk for mortality and nursing home placement and, therefore, may be appropriate for comprehensive geriatric assessment.

DESIGN

Prospective cohort study.

SETTING

Four HMO (Southern California Kaiser-Permanente) hospitals.

SUBJECTS

3,697 patients 65 years of age or older admitted to any inpatient service from July 1 through September 30, 1990.

MAIN OUTCOME MEASURES

Screening measures for standardized targeting criteria, administered 24-48 hours after admission.

RESULTS

Overall, 35.1% of patients screened met at least one inclusionary criterion, which is considerably higher than other published reports. The most commonly met criteria were incontinence, impairment in performing activities of daily living, malnutrition, and immobility. The percentage of patients meeting at least one criterion and meeting each criterion varied considerably among hospitals. The vast majority of patients (83%) who were judged appropriate for assessment met at least three criteria.

CONCLUSIONS

The yield of standardized criteria differs when applied to patients in different health care systems and to patients at different hospitals within a health care system, which may reflect differences in the populations being served and the practice styles of physicians and the delivery system. Because no single criterion identified more than approximately half of patients who were judged appropriate for assessment, it is likely that a battery of criteria will be necessary to identify these patients.

An investigation into the effects of aminoguanidine treatment on the plasma and blood of free-fed and dietary-restricted rats

An investigation has been made into the effect of oral aminoguanidine (50-60 mg kg-1 day-1) on the blood biochemistry of male Wistar rats which either had free access to food or were dietary-restricted (50% of the food consumed by the free access group). In control rats (i.e. without aminoguanidine treatment) three weeks of food restriction caused significant increases in plasma sodium and albumin and the erythrocyte count, haematocrit and haemoglobin. There were reductions in plasma calcium, phosphate, alkaline phosphatase activity, urea, triglycerides, creatinine, glucose and the red cell volume. Similar effects of food restriction were observed in aminoguanidine-treated rats. Aminoguanidine ingestion in free-fed animals caused a reduction in plasma creatinine concentration. In dietary-restricted rats, aminoguanidine ingestion reduced plasma sodium and total plasma proteins (largely as a result of a decline in albumin), and increased plasma urea concentrations. Aminoguanidine was added to plasma of control rats in-vitro to determine whether it interfered with the assay of urea and creatinine. At concentrations of 0.1 to 10 mg mL-1, aminoguanidine had no effect on urea determinations. However, aminoguanidine significantly reduced the apparent concentration of plasma creatinine by between 7 to 81%. The changes in plasma analytes in aminoguanidine-treated rats may be indicative of minor hepatic perturbations or kidney function, but the data also imply that prior nutritional state is a determinant of aminoguanidine effects.

Urinary excretion of nitrogenous and non-nitrogenous compounds in the chronic ethanol-fed rat

1. The metabolic consequences of chronic ethanol feeding was investigated by assay of urinary metabolites. Male Wistar rats were fed a liquid diet containing 35% of total energy as ethanol or isovolumetric, isocaloric and isonitrogenous amounts of the same diet in which ethanol was substituted by isocaloric glucose (controls). 2. At 6 weeks the entire skeletal muscle mass was reduced by approximately 20%. The urinary excretion of nitrogen, urea and uric acid increased by between 23 and 128%. Urinary creatinine excretion was not significantly altered. 3. Urinary excretion of magnesium was significantly increased by 43%. Urinary excretion of sodium, potassium, calcium and phosphate was increased slightly (i.e. 5-22%), but this change was not statistically significant. 4. Proton n.m.r. spectroscopic analysis showed that ethanol feeding reduced the urinary excretion of citrate and 2-oxoglutarate (by approximately 50%), suggesting decreased citric acid cycle activity. There was an increased excretion of alanine (44%), but excretion of succinate and acetate was not significantly altered. Ethanol in the urine of ethanol-fed rats comprised approximately 2% of total ethanol intake and less than 1% of total energy intake. 5. Lactose was detectable in urine of ethanol-fed rats, but not in control rats, reflecting the reported decreased intestinal lactase activity and increased gut permeability in alcoholics. Urinary galactose excretion decreased by 41%, but relatively large increases in lactate excretion (50%) did not achieve statistical significance. 6. It was concluded that chronic ethanol feeding causes disturbances in whole-body nitrogen homoeostasis and alterations in intermediary metabolism.

Measurement of protein synthesis by the phenylalanine flooding dose technique: effect of phenylalanine and anaesthesia on plasma electrolyte, enzyme and metabolite levels

Ten minutes after an intravenous flooding dose of phenylalanine to rats, plasma sodium and calcium concentrations were slightly reduced (by 2-7%) but no effects on potassium or phosphate were observed. Creatine kinase activities were significantly increased by phenylalanine injection (by 39%), but alkaline phosphatase, alanine aminotransferase, lactate dehydrogenase and aspartate aminotransferase activities were unaltered. Plasma concentrations of total proteins, albumin, cholesterol, triglycerides, urea, creatinine and glucose were also unaffected. In the presence of anaesthesia, phenylalanine injection had almost identical effects, although the increase in creatine kinase activities did not reach statistical significance. Anaesthesia for 10 min reduced plasma potassium concentrations (by 27%), and calcium (by 5%), though phosphate and sodium were unaltered. The activities of lactate dehydrogenase, creatine kinase and aspartate aminotransferase were reduced by between 36-52%, but alkaline phosphatase and alanine aminotransferase activities were unaltered by anaesthesia. Plasma concentrations of total proteins and albumin were also reduced (both by 9%), but glucose concentrations were increased (by 33%). Anaesthesia had no other significant effects on cholesterol, triglycerides, urea or creatinine concentrations. The qualitative effects of anaesthesia in the presence of raised free phenylalanine concentrations were similar. It was concluded that, except for creatine kinase, determinations of plasma constituents in phenylalanine-injected rats could be made without overt interpretational errors. However, caution is required in interpreting data on plasma constituents from anaesthetized rats.

Activity of cardiac enzymes measured in the coronary sinus in acute myocardial infarction

Three patients with acute infarction of the anterior wall of the heart underwent catheterisation of the coronary sinus. Samples were taken for estimation of activity of cardiac enzymes. A small gradient was demonstrated between the sinus and the venous blood, suggesting that the coronary sinus is the conduit by which these enzymes are liberated into the systemic circulation.

Antimicrobial effect of chlorhexidine in a controlled release delivery system

Chlorhexidine is widely used as a mouth rinse in the prevention and treatment of periodontal diseases and dental caries. The purpose of the present study was to evaluate the in vitro antimicrobial effect of chlorhexidine in a controlled release delivery system. The controlled release dispenser comprised a polymeric inner core matrix containing the medicament with an outer vinyl membrane controlling the drug release. The effect on the following bacteria was studied: Actinobacillus actinomycetemcomitans, Actinomyces viscosus, Streptococcus mutans, Wolinella recta, Bacteroides gingivalis, Bacteroides intermedius, Eikenella corrodens, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. Chlorhexidine-containing vinyl patches with a diameter of 5.5 mm were placed on blood agar plates containing the various bacteria. The plates were incubated aerobically or anaerobically at 37 degrees C for 24 h or longer, when appropriate, and examined for inhibition of bacterial growth. Distinct zones of inhibition were seen surrounding all vinyl patches on all plates with all bacteria. Thus, the vinyl dispenser appeared to be an effective vehicle for releasing chlorhexidine to a localized area such as the surface of a tooth, a periodontal pocket, or a root canal.

The pulmonary hypertension of sclerosing agents is prevented by cyclooxygenase inhibitors

Sodium morrhuate and sodium tetradecylsulfate are injected during endoscopic sclerotherapy to control variceal bleeding. When administered to sheep they cause transient pulmonary hypertension and increase protein poor lung lymph flow. To determine the etiology of these alterations, we studied three groups of sheep after establishing acute lung lymph fistulas. In Group 1, indomethacin or ibuprofen was infused. In Group 2, 2.5 cc of sodium morrhuate was injected alone (2A) or after indomethacin or ibuprofen pretreatment (2B). In Group 3, 2.5 cc of sodium tetradecylsulfate was given intravenously either alone (3A) or after indomethacin or ibuprofen (3B). When sclerosing agents were given alone (Group 2A and 3A) pulmonary artery pressures increased three-fold at 30 seconds postinjection to 37 +/- 4.4 and 39 +/- 5.7 mmHg respectively with a slow return to baseline over two hours. Lymph flow increased significantly from 1.3 +/- 1.5 to 2.7 +/- 1.5 cc/30 minutes after sodium morrhuate and from 1.2 +/- .62 to 2.7 +/- 1.7 cc/30 mins at 30 minutes after sodium tetradecylsulfate and the lymph/plasma albumin ratio fell. Increased lymph flow persisted through 120 minutes. In those animals receiving a sclerosing agent after indomethacin or ibuprofen (2B and 3B) there was no change in pulmonary artery pressure, lymph flow, lymph plasma albumin ratio, or lung wet weight to dry weight ratios. We conclude that the pulmonary hypertension and increased protein poor lymph flow are mediated by prostaglandins.

The oxygen free radical system: potential mediator of myocardial injury

The sequential univalent reduction of oxygen gives rise to very reactive intermediate products including superoxide anion radical, hydrogen peroxide and free hydroxyl radicals. Normally, the tissue concentration of these intermediate products of oxygen is severely limited; however, if oxygen free radicals are produced in excess of the capacity of the tissues to eliminate them, they may cause serious damage. The biochemistry and possible sources of free radical generation in animal models of ischemic/reperfusion injury are reviewed. The ability of scavengers of oxygen free radicals to improve mechanical, mitochondrial and sarcoplasmic reticulum function in animal models of ischemic/reperfusion injury suggests that oxygen free radicals are partly responsible for myocardial injury in these models. Future research should be directed at establishing the relevance of oxygen radical-mediated myocardial injury in the experimental setting to analogous clinical situations.

Oxygen radicals in the adult respiratory distress syndrome, in myocardial ischemia and reperfusion injury, and in cerebral vascular damage

Recent work suggests that oxygen radicals may be important mediators of damage in a wide variety of pathologic conditions. In this review we consider the evidence supporting the participation of oxygen radicals in the adult respiratory distress syndrome, in ischemia reperfusion injury in the myocardium, and in cerebral vascular injury in acute hypertension and traumatic brain injury. In the adult respiratory distress syndrome there is active sequestration of polymorphonuclear neutrophils in the pulmonary vascular system. There is evidence that activation of these neutrophils results in the production of oxygen radicals which injure the capillary membrane and increase permeability, leading to progressive hypoxia and decreased lung compliance which are hallmarks of the syndrome. In acute arterial hypertension or experimental brain injury oxygen radicals are important mediators of vascular damage. The metabolism of arachidonic acid is the source of oxygen free radical production in these conditions. In myocardial ischemia and reperfusion injury, the ischemic myocyte is "primed" for free radical production. With reperfusion and reintroduction of molecular oxygen there is a burst of oxygen radical production resulting in extensive tissue destruction. Myocardial ischemia--reperfusion injury shares in common with the other two syndromes activation of the arachidonic acid cascade and acute inflammation. Thus it would appear that the generation of toxic oxygen species may represent a final common pathway of tissue destruction in several pathophysiologic states.