A survey of emergency medicine in 36 countries

OBJECTIVE

To assess the current level of development of emergency medicine (EM) systems in the world.

DESIGN

Survey of EM professionals from 36 countries during a 90-day period from Aug. 25 to Nov. 24, 1998.

PARTICIPANTS

Thirty-six EM professionals from 36 countries and 6 continents completed the survey. Thirty-five (97%) were physicians, of whom 25 (69%) gave presentations at 1 of 4 international EM conferences during the study period. Three potential participants from 3 countries were excluded because of language barriers. Five additional participants from 5 other countries did not respond within the study period and were excluded.

MEASUREMENTS

Respondents completed a 103-question questionnaire about the presence of EM specialty, academic, patient care, information and management systems and the factors influencing the future of EM in their countries.

RESULTS

The overall response rate was 88%. Nearly all respondents (97%) stated that their countries had hospital-based emergency departments (EDs). More than 80% of respondents reported that their countries have emergency medical services (EMS), national EMS activation phone numbers and ED systems for pediatric emergency care. More than 70% stated that their countries had national EM organizations, EM research, ED systems for patient transfer and peer review and emergency physician (EP) training in Advanced Cardiac Life Support (ACLS) and the ability to perform rapid sequence intubation. More than 60% reported ED systems for trauma care and triage and EP training in Advanced Trauma Life Support (ATLS) and the ability to perform thrombolysis for acute myocardial infarction. Fifty percent reported EM residency training programs, official recognition of EM as an independent specialty, and EM journals.

CONCLUSIONS

Basic emergency medicine components now exist in the majority of countries surveyed. These include many specialty, academic, patient care and administrative systems. The foundation for further EM development is widely established throughout the world.

Relationship between reported and measured sleep times: the sleep heart health study (SHHS)

STUDY OBJECTIVE

Subjective and objective assessments of sleep may be discrepant due to sleep misperception and measurement effects, the latter of which may change the quality and quantity of a person's usual sleep. This study compared sleep times from polysomnography (PSG) with self-reports of habitual sleep and sleep estimated on the morning after a PSG in adults.

DESIGN

Total sleep time and sleep onset latency obtained from unattended home PSGs were compared to sleep times obtained from a questionnaire completed before the PSG and a Morning Survey completed the morning after the PSG.

PARTICIPANTS

A total of 2,113 subjects who were > or = 40 years of age were included in this analysis.

MEASURES AND RESULTS

Subjects were 53% female, 75% Caucasian, and 38% obese. The mean habitual sleep time (HABTST), morning estimated sleep time (AMTST), and PSG total sleep times (PSGTST) were 422 min, 379 min, and 363 min, respectively. The mean habitual sleep onset latency, morning estimated sleep onset latency, and PSG sleep onset latency were 17.0 min, 21.8 min, and 16.9 min, respectively. Models adjusting for related demographic factors showed that HABTST and AMTST differ significantly from PSGTST by 61 and 18 minutes, respectively. Obese and higher educated people reported less sleep time than their counterparts. Similarly, small but significant differences were seen for sleep latency.

CONCLUSIONS

In a community population, self-reported total sleep times and sleep latencies are overestimated even on the morning following overnight PSG.

Impact of an outbreak of severe acute respiratory syndrome on a hospital in Taiwan, ROC

STUDY OBJECTIVE

To estimate the impact of the severe acute respiratory syndrome (SARS) outbreak in early 2003 on a tertiary care hospital in Taiwan, ROC.

METHODS

The study estimated the utilisation of resources related to infection control, SARS related medical services, and routine medical services, and SARS related medical outcomes at National Cheng Kung University Hospital (NCKUH) from 25 March to 16 June 2003 through a cross sectional survey of hospital records.

RESULTS

A mean of 5100 persons per day (95%CI 4580 to 5610) underwent fever screening at the outpatient and emergency department (ED) entrances to the hospital, of which 35 per day (95% CI 30 to 40) were referred for further evaluation for suspected or probable SARS. ED isolation surge capacity was created via 12 new beds outside the ED: eight for SARS assessment, three for patients awaiting in hospital bed assignment, and one for resuscitation. A total of 382 patients were fully evaluated for suspected or probable SARS outside the ED, of which 27 were admitted. The mean numbers of outpatient clinic patient visits, ED visits, ED trauma patient visits, ED admissions, hospital admissions, and operative procedures decreased during the outbreak. Thirty eight patients were hospitalised with suspected SARS, of which three received the final diagnosis of probable SARS. Two patients with probable SARS died. No cases of nosocomial SARS transmission occurred.

CONCLUSIONS

This SARS outbreak was associated with substantial use of hospital and ED resources aimed at infection control, comparatively less use of resources related to the medical care of patients with suspected or probable SARS, and decreased use of routine medical services.

Identification of sleep-disordered breathing in children: variation with event definition

STUDY OBJECTIVES

To determine the effect of varying approaches to the measurement of the respiratory disturbance index (RDI) on identification of sleep disordered breathing (SDB) in children.

DESIGN

Cross-sectional study of SDB in a well-characterized birth cohort (stratified for term and preterm birth) participating in longitudinal studies of cognition and behavior.

SETTING

Community-based; overnight studies conducted in participant's homes.

PARTICIPANTS

433 children, ages 8-11 years, un-referred for clinical assessment of SDB.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Participants underwent unattended overnight in-home recording of respiratory inductance plethysmography, pulse oximetry, body position, and heart rate. The relationships among RDIs derived from various definitions of apnea and hypopneas and thresholds for frequency of events were assessed. Median RDI varied by more than 20-fold for definitions using the more liberal criteria for event definition (all respiratory events; i.e., central or obstructive events and hypopneas with no requirement for associated desaturation) to the most conservative definition (using obstructive apneas only or obstructive apnea and hypopneas requiring a 5% associated desaturation). Prevalence estimates for SDB based on RDIs that included central apneas were 40% to 140% higher than those that excluded central apneas.

CONCLUSIONS

Different approaches for quantifying RDI contribute to substantial variability in identification and classification of SDB in children and will lead to discrepant estimates of its presence and severity.

Emergency medicine in Southern Brazil

Emergency medicine is developing rapidly in southern Brazil, where elements of both the Franco-German and the Anglo-American models of emergency care are in place, creating a uniquely Brazilian approach to emergency care. Although emergency medical services (EMS) in Brazil have been directly influenced by the French mobile EMS (SAMU) system, with physicians dispatched by ambulances to the scenes of medical emergencies, the first American-style emergency medicine residency training program in Brazil was recently established at the Hospital de Pronto Socorro (HPS) in Porto Alegre. Emergency trauma care appears to be particularly developed in southern Brazil, where advanced trauma life support is widely taught and SAMU delivers sophisticated trauma care en route to trauma centers designated by the state.

International emergency medicine and the recent development of emergency medicine worldwide

Emergency medicine is being established as a unique and independent specialty throughout the world. Two major models of emergency care delivery exist in the world today: the Anglo-American and the Franco-German model. Most countries developing new systems of emergency care are following the Anglo-American model and are recapitulating the sequence of steps taken to establish the systems of emergency medicine in the United States. The most important step in the development of emergency medicine in other countries is the recognition that emergency medicine incorporates a unique body of knowledge requiring specialized practitioners or emergency physicians. A global network of international emergency medicine is assisting the development of emergency medicine worldwide and now includes international organizations, academic institutions, and individuals in countries where emergency medicine is mature and their counterparts in countries where emergency medicine is developing. The multilevel exchange of information through various modalities, such as international conferences, physician exchange programs, and print or electronic media, is playing a vital role in the search for internationally applicable systems of emergency care.

The recent development of emergency medicine in South Korea

Emergency medicine has developed rapidly in South Korea in the past decade, giving Korea one of the most advanced systems of emergency medical care in Asia. This article reviews the overall health care system and medical climate in Korea, as well as the great progress made in establishing emergency medicine as a specialty. It also describes the many improvements implemented in academic emergency medicine, emergency patient care, and emergency medicine management systems. Although the current economic crisis offers new challenges, much optimism remains about the future of this new Korean specialty.

Colorectal neoplasms detected colonoscopically in at-risk members of colorectal cancer families stratified by the demonstration of DNA microsatellite instability

This study compared colonoscopic findings in families meeting the Amsterdam criteria (A) for hereditary non-polyposis colorectal cancer (HNPCC) but stratified according to whether the familial cancers showed DNA microsatellite instability. DNA was extracted from paired samples of normal and cancer, and microsatellite instability was analysed at up to six loci. Families were termed replication error positive (RER+) when at least 50% of tumours tested per family were positive. Of 26 families studied 17 were RER+ and 9 were RER-. Cancers in the A/RER- families showed no right-sided predilection (P < 0.001). Colonoscopies have been performed on 182 at-risk members of A/RER+ families and 60 members of A/RER- families. More of the at-risk members of A/RER-families were found to have adenomas at colonoscopy (P = 0.095), but these were smaller than those of A/RER+ families (P = 0.19). The adenoma:carcinoma ratio was twice as high in A/RER- families (13:1) as in A/RER+ families (7:1). One of the A/RER- families had hyperplastic polyposis. The others do not appear to have attenuated familial adenomatous polyposis and are similar to the adenoma families or late-onset colorectal cancer families described by others. This study illustrates the importance of molecular technology in separating HNPCC from syndromes with overlapping phenotypes.

Changing Children's Perceptions of the Elderly:

Age-integrated programming has become an effective way to bring the young and old closer together. This article reviews some of the relevant literature and then describes a study involving the Intergenerational Partners Project, a program which stressed the use of age-integrated friendship. The project involved a number of activities shared by fourth graders and elderly volunteers. The Children's Perception of Aging and Elderly (CPAE) inventory administered before and after the program indicated significant attitude improvement toward the elderly by participating students. Other information from the youth and elderly participants also indicated positive qualities of the partners program. The format used to organize the project is presented and the planned activities are identified. Recommendations for intergenerational programming are discussed.

Erythropoietin levels with treatment of obstructive sleep apnea

The effect of nasal continuous positive pressure (CPAP) treatment on erythropoietin (EPO) was examined by measuring diurnal serum EPO levels before and twice (over the 3rd day and over 1 day on recall after > or = 1 mo of therapy) after initiation of treatment in 12 obstructive sleep apnea syndrome patients with normal hemoglobin, hematocrit, creatinine, blood urea nitrogen, and albumin levels. Over each study day, oxygen saturation was measured by an ambulatory pulse oximetry system. Patients spent 27 +/- 9% (SE) of time below oxygen saturation of 88% vs. 2.1 +/- 0.6% after initiation of nasal CPAP treatment (P < 0.01). The number of desaturation events per hour of sleep before nasal CPAP treatment was 62 +/- 6 vs. 9 +/- 2 with nasal CPAP (P < 0.01). EPO levels measured by radioimmunoassay were drawn every hour before and at 3 days (n = 9) and before and at recall (n = 0) after initiation of CPAP therapy. The mean serum EPO level was higher before treatment (61 +/- 14 mU/ml) than that at 3 days (38 +/- 10 mU/ml, P < 0.01) or at recall (32 +/- 7 mU/ml, P < 0.01). We conclude that nasal CPAP treatment of sleep-disordered breathing will reduce diurnal levels of EPO.

Nasal response to carrot and lettuce challenge in allergic patients

BACKGROUND

Food allergies are usually recognized by historical triggers; yet, on occasion, objective testing may be needed to demonstrate allergic causes more convincingly.

OBJECTIVE

Two atopic adult patients presented with respiratory and/or ocular symptoms with an unusual association to handling or eating of vegetables. A third atopic patient presented without attribution of symptoms to vegetable exposure. In all, work-up had revealed positive skin tests and in vitro assays for specific IgE to carrot and/or lettuce; none had gastrointestinal complaints.

METHODS

To assess further these unusual histories and/or IgE antibody findings, laboratory challenge was performed with nasal resistance being used as a monitor of rhinitic reaction.

RESULTS

The first two patients had prolonged nasal objective responses to challenge; the third had a transient response to one of two challenges.

CONCLUSION

We conclude that lettuce and carrot can account for clinically significant IgE-mediated allergic reactions, manifested by nasal obstruction. This laboratory reaction to foodstuffs appears to correlate with patient-reported upper airway and ocular symptoms.

Functional electrical stimulation and respiration during sleep

During obstructive sleep apnea (OSA), respiratory activation of upper airway muscles, particularly genioglossus, is ineffective during sleep. Functional electrical stimulation (FES) of muscles reportedly reduces the number and length of OSAs. Our goals were to examine the effect of FES on sensation during wakefulness and on OSA events. Studies were performed in 11 subjects: 4 healthy asymptomatic subjects and 7 patients with OSA. Surface electrodes placed on the submental region produced discomfort; however, during sleep, the stimulus intensity producing arousal was significantly greater than that producing barely tolerable discomfort during wakefulness. Additionally, we developed a protocol for placement of fine-wire electrodes into the neurovascular bundle of the hypoglossal nerve, using recognizable radiographic features and computerized axial tomography as guides. In these patients, while awake, optimal wire placement was associated with visible tongue protrusion without discomfort. With both surface stimulation and fine-wire FES, during sleep the stimulus intensity required to produce obvious electroencephalographic arousal was significantly greater than that producing a barely tolerable sensation while awake. During apneic events, the application of surface stimulation had an inconsistent effect, terminating 22% of the apneas, and fine-wire FES also had a limited impact, terminating 23% of the apneic events. We conclude from our studies that subjects tolerate surface and fine-wire FES to higher stimulus parameters during sleep than during wakefulness but that both approaches have an inconsistent effect on apneas during sleep.

Arterial oxygen saturation over time and sleep studies in quadriplegic patients

This study evaluated arterial oxygen saturation (SaO2) over time in a randomly selected group of quadriplegic patients to assess whether clinical history prospectively correlated with profiles of oxygen saturation. In 16 stable male quadriplegic patients (C4-T5), we used pulse oximetry to measure SaO2 over a 24 hour period. Measured values of SaO2 were formatted into a cumulative frequency distribution of SaO2 over time. The cumulative SaO2 values from the quadriplegic patients were compared to SaO2 values in a control group of 12 age-matched healthy male subjects. Ten quadriplegic patients had SaO2 profiles comparable to the range observed in healthy subjects. Six quadriplegic patients had SaO2 profiles outside of the normative range. These 6 exhibited cyclic desaturations (> 4%) during periods of behaviorally-defined sleep, suggestive of sleep-disordered breathing. During wakefulness, however, their values of SaO2 were within the normative range. With respect to level of injury, age, time after injury, or medication use, there was no difference between the six 'hypoxic' quadriplegic patients and the 10 'normoxic' quadriplegic patients. Five of the 6 hypoxic patients had a positive medical history of snoring and increased daytime sleepiness, as compared to 6 of 10 normoxic patients who gave a similar history. We also performed polysomnographic studies in a subgroup of 7 quadriplegic patients. In this subgroup, sleep-disordered breathing was observed in 3 patients (AHI of 54/53/12 per hour, respectively). We conclude that in quadriplegic patients, in whom there is a low clinical suspicion for sleep-disordered breathing, there can occur significant decreases in SaO2 over time.

The nasal response to exercise in patients with cystic fibrosis

This study has evaluated the nasal response to exercise in patients with cystic fibrosis (CF), a genetic disease in which factors such as chronic lung disease and/or nasal polyposis might be anticipated to modify nasal function responses. Measurements of nasal resistance (NAR) by posterior rhinomanometry and specific airway resistance (sRAW) were made before and 1, 5, 10, and 30 min after a 4-min period of exhausting legwork exercise (50% predicted maximal) in 19 CF patients (aged 11-29 years) and 10 healthy subjects (aged 11-31 years). One minute after exercise, healthy subjects showed a 54 +/- 5% (mean +/- SEM; standard error of the mean) relative fall from baseline in NAR and CF patients showed a 31 +/- 8% relative fall from baseline (p < 0.05). There were no significant differences in the magnitude or pattern of recovery in NAR after exercise (1 to 30 min) between the groups, largely because of the variability in NAR responses in CF patients. Exercise did not result in significant changes in sRAW in either group. We also found that a history or presence of nasal polyposis does not significantly affect functional nasal responses to exercise. Our conclusion is that the CF genotype and its airway sequelae do not substantively affect the control of the nasal response to exercise.

Extended monitoring of oxygen saturation in chronic lung disease

The goal was to determine values of oxygen saturation from oximetry measurements over extended time periods in the context of prescribing or discontinuing supplemental oxygen. For group 1, when supplemental oxygen therapy was not in use, mean SpO2 values were significantly lower than when it was in use. Without supplemental oxygen, six of eight patients spent greater than 10 percent of the time at or below 88 percent saturation. For group 2, three of the nine patients spent 10 percent of the time at or below 88 percent SpO2. In 16 of 17 patients, lowest room air recorded values of SpO2 were less than 88 percent. We conclude that in many patients with chronic respiratory illness, prolonged monitoring of SpO2 will disclose the presence of hypoxemia. There may be substantial differences in health care cost and outcome depending upon the criteria chosen to prescribe or continue supplemental oxygen.

Serum erythropoietin levels and blood component therapy after autologous bone marrow transplantation: implications for erythropoietin therapy in this setting

To determine the potential impact of recombinant human erythropoietin (EPO) therapy in patients undergoing autologous bone marrow transplantation (BMT) and colony-stimulating factor therapy, we assayed endogenous serum EPO levels and noted blood transfusion requirements in relapsed non-Hodgkin's lymphoma patients treated with high-dose chemo-radiation therapy and autologous BMT. Hematocrit and reticulocyte counts were determined daily, and hematocrit was maintained in the 25-30% range by transfusion according to criteria established by our hospital transfusion committee. EPO levels were measured by radioimmunoassay and were determined at baseline, throughout therapy, and 2 and 3 months after BMT. Serum EPO levels increased more than 25-fold above baseline in most subjects after initiating chemoradiation therapy. No correlation was noted between serum EPO and hematocrit, reticulocyte count or serum creatinine. Total red blood cell units transfused ranged from 4 to 15 (mean 7.7). Mean total donor exposures (red blood cell plus platelet units transfused) were 83.6 units (range 16-175). Serum EPO levels increased early in the course of preparation for autologous BMT and remained elevated for at least 2-3 weeks thereafter although at a lower level. Red blood cell transfusions were required despite very high EPO levels after BMT. Red cell transfusions, moreover, accounted for only 9.2% (69 of 746) of total donor exposures and only 5.8% (42 of 746) of donor exposures during the interval when pharmacologic doses of erythropoietin might be of benefit. In contrast to the potential benefit of colony-stimulating factors such as G-CSF and GM-CSF in BMT, our study suggests limited value for erythropoietin therapy in this setting.

Diurnal variations in serum erythropoietin levels in healthy subjects and sleep apnea patients

We measured arterial oxygen saturation (SaO2) and serum erythropoietin (EPO) levels in patients with obstructive sleep apnea syndrome (OSAS) and in healthy subjects. SaO2 profile was analyzed as the cumulative distribution of SaO2 over time. OSAS patients spent 25.5 +/- 30.9% (SD) of the time at SaO2 of less than 88% vs. 0.64 +/- 1.6% in healthy subjects (P less than 0.05) and had 59 +/- 25 desaturations (greater than 4%) per hour vs. less than 5 per hour in healthy subjects (P less than 0.05). EPO measurements (radioimmunoassay) were made in blood samples withdrawn every 1 or 2 h over a 24-h period. The mean EPO concentration was higher (P less than 0.05) for OSAS patients (45 +/- 33 mU/ml) than for normal subjects (17 +/- 8 mU/ml). There was a significant variability in EPO values over the 24-h period. To analyze the EPO pattern over 24 h, EPO time series were fit to a general cosine function. Data from normal subjects conformed to a cosine function with an amplitude of 3.5 +/- 2.1 (CV of 60%) and an acrophase of 1,000 +/- 184 min after 0800 (CV of 18%), indicating a zenith about 1 A.M. and a nadir around 1 P.M. Data from OSAS subjects fit a similar cosine function with an amplitude of 19.9 +/- 41.0 (CV of 206%) and acrophase of 582 +/- 408 min (CV of 70%), indicating a greater variability in the magnitude and the timing of peak serum EPO levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Nasal flow-resistive responses to challenge with cold dry air

Recent studies have suggested that the inhalation of cold air through the nose is associated with the subsequent release of mediators of immediate hypersensitivity. To determine if mucosal surface heat and water loss influence the nasal functional response to cold air, we measured nasal resistance by posterior rhinomanometry before and 1, 5, and 10 min after a 4-min period of isocapnic hyperventilation (30 l/min) through the nose in nine healthy subjects (5 males, 4 females; aged 25-39 yr) while they inhaled air at 0 degrees C. During the challenge period, the subjects breathed either in and out of the nose or in through the nose and out through the mouth. No changes in nasal resistance developed when subjects breathed exclusively through the nose; however, when subjects breathed in through the nose and out through the mouth, nasal resistance was increased 200% at 1 min (P less than 0.01) after the challenge and returned to baseline values by 10 min after cessation of the challenge. These data indicate that nasal functional responses to cold dry air are dependent on the pattern of the ventilatory challenge. If the heat given up from the nasal mucosa to the incoming air is not recovered during expiration (as is the case with inspiration through the nose and expiration through the mouth), nasal obstruction will occur. Hyperpnea of cold air, per se, does not influence nasal resistance.

Occupational allergic rhinitis in the hair care industry: reactions to permanent wave solutions

This report details our observations on rhinitic reactions in nonatopic professional beauticians in whom an etiologic agent for occupational symptoms was not previously determined. Exposure to permanent wave solutions in a laboratory setting caused clinical symptoms and significant laboratory evidence of nasal airway obstruction. In one patient, previous treatment with cromolyn sodium reduced, but did not completely eliminate, the reaction.

A comparison of a new reflectance oximeter with the Hewlett-Packard ear oximeter

The purpose of this study was to characterize the accuracy and dynamic response characteristics of traditional transmittance pulse oximeters and a new reflectance pulse oximeter with regard to the current standard in oximetry, the Hewlett-Packard ear oximeter. Studies were performed with 15 healthy male and female subjects. A rebreathing technique was employed to produce a steady fall in oxygen saturation and to maintain constant, eucapnic, end-tidal CO2 levels. The oximeters' analog outputs were recorded by a Western Graphtec Linearecorder and by an IBM-PC utilizing an analog-to-digital converter for data collection at 5 Hz. The agreement between two clinical methods of measurement was used as the statistical technique of comparing new technology (pulse oximetry) with the current standard (Hewlett-Packard ear oximetry). The mean of the difference between the Hewlett-Packard and the pulse oximeter with reflectance sensor was 0.28%, with a range of difference of +/- 3.49%. This value was similar to that of the transmittance oximeters (Criticare 501+: 0.92 +/- 2.11), (Physio-Control: 3.15 +/- 2.04), (Ohmeda 3700: 2.05 +/- 2.06). There was virtually no response-time difference between the reflectance oximeter with the sensor placed on the subject's forehead and the Hewlett-Packard ear oximeter. The authors conclude that the accuracy of the reflectance oximeter is within the limits of clinical acceptance for monitoring and trending of arterial oxygen saturation in healthy subjects.

Occupational allergic rhinitis reaction to psyllium

We report studies that document a specific rhinitic reaction that developed as a result of occupational exposure to a psyllium-based powdered laxative. This nurse had a nonatopic family history, personal evidence of atopy (skin test reactions to pollen, cat dander, and house dust), and a significant elevation of antipsyllium IgE. Measurements of nasal and lower airway resistance documented only nasal obstruction to brief inhalational challenge to the laxative. Symptomatic relief was achieved with prior treatment with cromolyn. We suggest that nasal airway challenge can document and assess treatment for occupational rhinitis.

Natural cytotoxicity of human serum. A natural IgM 'antibody' sensitizes transformed murine cells to the lytic action of complement

The natural cytotoxicity of human serum on murine L cells, EA and Sa 180 cells is expressed as a rapid cytolysis at 37 degrees C. This cytotoxic system is analyzed as to its active constituents and their functional relationships. Ultrastructural studies indicate that cell injury and death are initiated within 10 min by membrane disruption. A trypan blue assay for cell death was used to study serum toxicity in individual normal healthy adults, pregnant females and newborn infants. Pregnancy sera, particularly in the 2nd and 3rd trimesters, were consistently more toxic than male serum or nonpregnant females. Cord serum was typically nontoxic. Pools of normal fresh pregnancy serum were used for immunochemical analysis of the cytotoxic activity. By a variety of immunologic and immunochemical techniques it was shown that the cytotoxicity was, in part, due to the combined action of alternative and classical pathways of complement, the former being more prominent. The lytic action of complement was shown to be greatly amplified by the prior adsorption of IgM on the target cells' surface. This IgM is a critical determinant of the cytotoxic reaction. It probably contains a natural 'antibody' to cell surface antigen(s), whose combination activates both pathways of C.

Transformation of an arachidonic acid hydroperoxide into epoxyhydroxy and trihydroxy fatty acids by liver microsomal cytochrome P-450

In the absence of NADPH, the addition of an arachidonic acid hydroperoxide, 15-hydroperoxyeicosa-5,8,11,13-tetraenoic acid, to liver microsomes, prepared from phenobarbital-treated rats, resulted in the formation of two major metabolites and several minor products, some of which have been purified by reverse-phase high-performance liquid chromatography. We propose the structures of the two major products to be 13-hydroxy-14,15-epoxyeicosa-5,8,11-trienoic acid and 11,14,15-trihydroxyeicosa-5,8,12-trienoic acid based on spectral characteristics and mass spectral analysis of derivatives of the compounds. A potential heterolytic cleavage product, 15-hydroxyeicosa-5,8,11,13-tetraenoic acid, was not a product of the reaction. Ferric cytochrome P-450 catalyzed the formation of these products as shown by the inability of boiled microsomes to support the reaction, the inhibition of epoxyhydroxy and trihydroxy fatty acid formation by imidazole derivatives which bind tightly to the ferric heme iron of cytochrome P-450, and the inability of carbon monoxide (which binds to ferrous P-450) and free iron chelators (EDTA and diethylenetriaminepentaacetic acid) to inhibit product formation. These results show that liver microsomal cytochrome P-450, in addition to its role in the NADPH-dependent metabolism of arachidonic acid, can utilize a hydroperoxide to produce an interesting series of potentially important arachidonic acid metabolites.