l-Arginine Pathway Metabolites Predict Need for Intra-operative Shunt During Carotid Endarterectomy

OBJECTIVE/BACKGROUND

Asymmetric dimethylarginine (ADMA) inhibits nitric oxide (NO) synthesis and is a marker of atherosclerosis. This study examined the correlation between pre-operative l-arginine and ADMA concentration during carotid endarterectomy (CEA), and jugular lactate indicating anaerobic cerebral metabolism, jugular S100B reflecting blood-brain barrier integrity, and with factors of surgical intervention.

METHODS

The concentration of l-arginine, ADMA, and symmetric dimethylarginine was measured in blood taken under regional anaesthesia from the radial artery of 55 patients prior to CEA. Blood gas parameters, concentration of lactate, and S100B were also serially measured in blood taken from both the radial artery and the jugular bulb before and after carotid clamping, and after release of the clamp. To estimate anaerobic metabolism, the jugulo-arterial ratio of CO₂ gap/oxygen extraction was calculated.

RESULTS

Positive correlation was found between pre-operative ADMA levels and the ratio of jugulo-arterial CO₂ gap/oxygen extraction during clamp and reperfusion (p = .005 and p = .01, respectively). An inverse correlation was found between the pre-operative l-arginine concentration and jugular lactate at each time point (both p = .002). The critical pre-operative level of l-arginine was determined by receiver operator curve analysis. If l-arginine was below the cutoff value of 35 μmol/L, jugular S100B concentration was higher 24 h post-operatively (p = .03), and jugular lactate levels were increased during reperfusion (p = .02). The median pre-operative concentration of l-arginine was lower in patients requiring an intra-operative shunt than in patients without need of shunt (median: 30.3 μmol/L [interquartile range 24.4-34.4 μmol/L] vs. 57.6 μmol/L [interquartile range 42.3-74.5 μmol/L]; p = .002).

CONCLUSION

High pre-operative ADMA concentration predicts poor cerebral perfusion indicated by elevated jugulo-arterial CO₂ gap/oxygen extraction. Low pre-operative l-arginine concentration predicts the need for a shunt. The inverse correlation between pre-operative l-arginine concentration and both jugular lactate and S100B during carotid clamping suggests a protective role of the NO donor l-arginine.

Have the boundaries of the 'grey zone' of perinatal resuscitation changed for extremely preterm infants over 20 years?

AIM

To determine the boundaries of the grey zone of discretionary resuscitation over the past 20 years.

BACKGROUND

As the likelihood of survival improves over time, the BW- and GA-specific boundaries of discretionary nonresuscitation should fall.

HYPOTHESIS

Between 1988 and 2008 reductions in BW- and GA-specific mortality would drive a parallel reduction in BW and GA boundaries of discretionary resuscitation.

METHODS

We determined the likelihood of resuscitation and survival to NICU discharge for all infants born <700 g or <26 gestational weeks from 1988 to 2008. In addition, for 1988, 1993, 1998, 2003 and 2008, we determined the BW and GA for the 10 smallest infants who were resuscitated, and the 10 largest infants who were not resuscitated. We excluded any infant born with congenital anomaly.

RESULTS

Mortality fell from 80% in 1988 to 28% in 2008, and as expected, the percentage who were resuscitated rose from 63% in 1988-93 to 95% in 2004-2008. However, unexpectedly, over the 20-year study period, the smallest infants who were resuscitated despite extreme immaturity did not change (450-550 g and 23-24 weeks) and the largest infants not resuscitated did not change (600-700 g and 23-24 weeks.

CONCLUSION

Neither the BW nor GA boundaries of the grey zone of discretionary resuscitation have fallen over the past 20 years. Factors guiding resuscitation at the border of viability are complex and incompletely understood.

Ischaemic postconditioning reduces serum and tubular TNF-α expression in ischaemic-reperfused kidney in healthy rats

OBJECTIVE

We studied the protective effects of postconditioning (PS) in healthy and hypercholesterolemic rats after renal ischaemia-reperfusion (IR) injury. We aimed to examine cytokine expression and apoptosis in tissue damage after revascularisation (TNF-α levels in serum and tissue).

METHODS

Male Wistar rats (n = 32) were divided into four groups. The animals of normal feed groups (NF) were fed with normal rat chow and the cholesterol feed groups (CF) were fed with 1.5% cholesterol containing diet for 8 weeks. Anaesthetized rats underwent a 45-min cross-clamping in both kidney pedicles. Ischaemia was followed by 120-min reperfusion with or without PS protocol (group PS vs. IR). Postconditioning was induced by four intermittent periods of ischaemia-reperfusion of 15-s duration each. Serum cholesterol, triglyceride, urea and creatinine levels were determined. Proinflammation was characterized by the measurement of serum TNF-α. Tissue injury in kidney was determined by formaline-fixed, paraffin-embedded tissue sections. Tissue TNF-α levels were determined by immunohistochemistry.

RESULTS

Significant elevation was observed in serum TNF-α level after IR injury in normal feed groups, which was reduced by PS. In CF group neither the elevation nor the postconditioning induced reduction were as significant as in the NF groups. In normal feed group PS caused a significant reduction in tissue TNF-α level which was significantly higher in CF.

CONCLUSIONS

Ischaemic postconditioning proved to be an effective defense against IR in NF groups, but it was ineffective in CF groups in kidney tissue.

End of life, death and dying in neonatal intensive care units in Latin America

AIM

Most analyses of end of life decisions in Neonatal Intensive Care Units (NICUs) have come from Europe/English-speaking countries. Would decisions be different in Latin American NICUs? Therefore, we aim to evaluate the approach to dying infants/families in NICUs in Latin America.

METHODS

Multinational descriptive study of all deaths in babies born at >22 weeks in eight NICUs in five Latin American countries. Deaths were categorized as: (i) no Cardiopulmonary Resuscitation (CPR) or life support offered; (ii) life support initiated but do not resuscitate (DNR) orders written or no CPR provided; (iii) full life support and CPR; and (iv) unclassifiable.

RESULTS

There were 100 deaths, 81% in >27 weeks. Seventeen infants received no CPR/life support at birth, 10 died in DR and seven in NICU. There were 27 infants in group 2, 54 in group three and two in group 4. No baby had care withdrawn or care withdrawn/CPR withheld. Thirty-two infants had 'do not resuscitate' order. Decisions without parents' involvement in 15%, both parents present at death 24% and sedatives/narcotics documented 14%.

CONCLUSIONS

Latin American NICUs differ from those in Northern Europe/English-speaking countries. More deaths are accompanied by full life support and CPR. DNR orders are rare. Withdrawal of life support is virtually non-existent. Latin American's doctors are more likely to make decisions without the objections of family about withholding life-sustaining treatment.

Preconditioning is a method that may reduce the negative side-effect of pneumoperitoneum

Increased intra-abdominal pressure during laparoscopy leads to hypoxia due to reduced blood flow. Aim of our study was to investigate whether preconditioning can reduce this negative effect of the pneumoperitoneum. Fifty female Wistar rats were used, divided into 5 groups. I: Sham operation (Sham), II: conventional pneumoperitoneum (PP), III: transvaginal pneumoperitoneum (TV), IV: preconditioning for 2.5 minutes in two cycles (Pre 2.5), V: preconditioning for 5 minutes (Pre 5). Malondialdehyde (MDA), reduced glutathione (GSH), sulfhydrylgroup (SH-) concentrations, superoxide-dismutase (SOD) and mieloperoxidase (MPO) activity, and anti-apoptotic pathway marker p-AKT level and inflammatory cytokine TNF-α were measured. SOD activity and GSH concentration were decreased in PP and TV groups comparing to Sham and preconditioning groups. MPO activity was decreased also in PP and TV groups comparing to the Sham group but in the preconditioning groups it has remained high. MDA concentration in plasma was increased in PP and TV groups comparing to Sham and preconditioning groups. There was no difference in the case of blood MDA and SH-concentrations between groups. Anti-apoptotic pathway marker p-AKT level was decreased in the TV group comparing to the sham and preconditioning groups. TNF-α level was increased in TV and preconditioning groups compared to the sham group. According to the results preconditioning can reduce negative effects of pneumoperitoneum.

Effect of vitamin E on reperfusion injuries during reconstructive vascular operations on lower limbs

INTRODUCTION

The challenge against reperfusion injury and tissue oxidative stress, especially in vascular surgical interventions has an essential importance to reach the optimal clinical result. Numerous experimental attempts have proved the positive antioxidant effect of vitamin E in both chronic and acute phase models. In our study we monitored the effect of continuous preoperative treatment with vitamin E, on oxidative stress and tissue inflammation reactions developed after reconstructive operations.

PATIENTS AND METHODS

32 patients have been involved in a randomized, prospective study, all suffering from AFS occlusion proved by angiography, and all undergone supragenual reconstruction. Duration of ischemia and amount of tissues under vascular clamping were almost the same in all patients. In the group treated with E-vitamin, we administered 1 x 200 mg of vitamin E p/o from the preoperative day till the 7th post operative day. Patients of the second group did not receive vitamin E.

MATERIALS AND METHODS

Peripheral blood samples were collected immediately before operation and at the end of the second reperfusion hour (early reperfusion period). Late reperfusion period has been monitored by analyzing blood samples taken at 24th hour and 7th day next to the operative ischemia. Among oxidative stress parameters, direct measurement of reactive oxygen intermediator (ROI) and determination of antioxidant state (GSH, Total-SH group, SOD) have been performed. Malondialdehyde was chosen as marker for lipidperoxidation. Inflammation reactions were monitored up on expression of adhesion molecules (CD11a and CD18). We also controlled the oscillation of myeloperoxidase (MPO) activity.

RESULTS

Our study has proved that preoperative (from the preoperative day till the 7th post operative day) administration of 200 mg vitamin E could reduce the level of oxidative stress developed after ischemic-reperfusion insult (lipidproxidation, antioxidant enzymes). According to our results, the prooxidant-antioxidant imbalance also diminished in the group with E-vitamin treatment. We proved that elective administration of vitamin E could decrease the WBC activity (MPO activity, free radicals production, expression of adhesion molecules) and its consequential local inflammation process, during early reperfusion.

Caregivers attitudes for very premature infants: what if they knew?

BACKGROUND

Decisions about resuscitation of extremely premature babies are controversial. Such decisions may reflect poor understanding of outcomes.

OBJECTIVE

To compare caregivers' attitudes towards the resuscitation of a premature infant if they are only told the infant's gestational age or if they are only given prognostic information for infants at that gestational age.

DESIGN/METHODS

Residents and nurses involved in perinatal care were asked whether they would resuscitate a depressed AGA 24-week gestation infant at birth. In another question they were asked whether they would resuscitate a depressed preterm infant with a 50% chance of survival, knowing that of those who survived, 50% would have a development 'within normal limits', 20-25% a serious handicap and 40% with behavioural and/or learning disability.

RESULTS

Two hundred and seventy-nine caregivers responded (91% response rate). In the scenario that only presented gestational age, 21% of respondents would resuscitate. In the scenario that only presented prognostic statistics, 51% of respondents would resuscitate (p<0.05).

CONCLUSIONS

Providers of perinatal health care respond to vignettes differently depending upon the format in which information is provided. The relative unwillingness to resuscitate a baby of 24-week gestation is surprising since outcomes for such babies are the same or better than those we described in the scenario that provided only outcome data without specifying gestational age. Two explanations are possible: (1) respondents have irrational negative associations with low gestational ages or (2) respondents are unaware of actual outcomes.

Reperfusion injury and inflammatory responses following acute lower limb revascularization surgery

After revascularization of an acute arterial occlusion the development of a serious ischaemic-reperfusion injury is a menacing challenge and a hard task in peripheral vascular surgery. A whale of evidences point to oxidative stress, as an important trigger, in the complex chain of events leading to reperfusion injury. In the present study authors aimed to examine oxidative stress parameters, antioxidant-prooxidant state and leukocyte adhesion molecules (CD11a and CD18) expression following acute revascularization surgery of lower limb.10 patients were examined in the prospective randomized study. Peripheral blood sample was collected in ischaemic period, and after reperfusion in the 2nd and 24th hours, and on 7th day. Superoxide-dismutase activity, reduced glutathion concentration and leukocytes free radical production were measured. The degree of lipidperoxidation was marked with the quantity of malondialdehyde. The expressions of adhesion molecules were measured with flowcytometry.The speed and rate of free radical production significantly increased in the early reperfusion (p<0.05). The level of antioxidant enzymes decreased after revascularization. The CD11a and CD18 expression of the granulocytes significantly (p<0.05) decreased right after the revascularization, but with a gradual elevation until the 7th day they exceed the ischaemic value. Our results showed a time specific turnover of the sensitive antioxidant-prooxidant balance after revascularization operation.

Ischaemic postconditioning reduces peroxide formation, cytokine expression and leukocyte activation in reperfusion injury after abdominal aortic surgery in rat model

OBJECTIVE

We studied the protective effects of ischaemic postconditioning (PS) on ischemia-reperfusion injury of the lower extremities in a rat model of abdominal aortic intervention. We aimed to examine the evoked oxidative stress, cytokine expression and leukocyte activation after revascularisation surgery.

METHODS

Anesthetized animals (48 Whistar rats) underwent a 60 min infrarenal aorta cross-clamping. After the ischaemic period, an intermittent 4 times 15 s reperfusion--15 seconds ischaemic episodes--were applied (ischaemic postconditioning: group PS). Then we started a 120 min reperfusion in the aorta. In untreated group animals underwent a long ischaemia (60 min) and the following reperfusion (group IR). Peripherial blood samples were collected before operation, and in early (5, 10, 15, 30, 60 and 120 min) reperfusion periods. Serum peroxide level, TNF-alpha concentration, myeloperoxidase (MPO) activity and PMA-induced leukocyte ROS production were measured.

RESULTS

In PS group, plasma peroxide level elevation was significantly lower in very early reperfusion (5-30 min) comparing to non-conditioned IR group (10.04+/-1.9 microM/l vs. 16.91+/-3.67 microM/l, p<0.05). PS also reduced serum TNF-alpha concentration (167.41+/-31.26 microg/ml vs. 116.55+/-12.04 microg/ml, p<0.05), MPO activity (1.759+/-0.239 microM/ml vs. 1.22+/-0.126 microM/ml, p<0.05) and leukocyte activation detected by PMA-induced leukocyte ROS production (5.7+/-0.96 AU/10(3) cells vs. 4.63+/-0.69 AU/10(3) cells).

CONCLUSIONS

Ischaemic postconditioning could reduce ROI production after IR in early reperfusion period, thus limiting ROI mediated tissue lesion, cytokine-leukocyte activation and inflammatory responses. PS seems to be an effective tool in vascular surgery to reduce reperfusion injuries after revascularization interventions.

Effect of cardiopulmonary bypass on cytokine network and myocardial cytokine production

BACKGROUND

In addition to the well-investigated proinflammatory cytokine expression, there is an ever increasing interest in the field of anti-inflammatory response to cardiopulmonary bypass (CPB). Evidence suggests that myocardium serves as an important source of cytokines during reperfusion and application of CPB. The effect of coronary artery bypass graft (CABG) without CPB on myocardial cytokine production has not as yet been investigated.

HYPOTHESIS

Cardiopulmonary bypass can cause long-term disturbance in pro- and anti-inflammatory cytokine balance, which may impede a patient's recovery following surgery. Therefore, the effect of CPB on the balance of the pro-/anti-inflammatory cytokines network and myocardial cytokine outflow was assessed throughout a longer period after surgery.

METHODS

Twenty patients were scheduled for CABG with CPB and 10 had off-pump surgery. Blood samples were taken before, during, and over the first week following surgery. Coronary sinus blood samples were collected during surgery. The ratio of pro- and anti-inflammatory cytokines was calculated and the cytokine concentration of peripheral and coronary sinus blood were compared in both groups.

RESULTS

Pro-/anti-inflammatory cytokine ratio decreased early after CPB followed by a delayed and marked increase. A more balanced ratio was present following off-pump surgery. Coronary sinus levels of certain cytokines exceeded the concentration of systemic blood in the course of CPB but not during off-pump operation.

CONCLUSION

Patients show pro-inflammatory predominant cytokine balance at a later stage after CPB in contrast to those without CPB. The heart produces a remarkable amount of cytokines only in the course of surgery with CPB.

Expression of CD97 and Adhesion Molecules on Circulating Leukocytes in Patients Undergoing Coronary Artery Bypass Surgery

OBJECTIVE

Leukocyte activation is thought to be responsible for the adverse effects and postoperative complications following cardiopulmonary bypass (CPB). A novel cell surface molecule, CD97, is a sensitive marker of leukocyte and primary lymphocyte activation. The present study aimed to determine the activation of different leukocyte subsets by comparing the expression of CD97 and adhesion molecules (CD11, CD18) in patients receiving coronary surgery with or without CPB.

METHODS

30 patients were enrolled and scheduled for coronary bypass surgery under CPB (20 patients, group A) and with off-pump (OP) operation (10 patients, group B). Blood samples were taken before and during surgery, and over the following first week.

RESULTS

Here, we report an early decrease in CD97 expression of granulocytes (PMN) and monocytes (MC) followed by an intensive increase reaching the maximum on postoperative days 2 and 3 in patients operated with CPB. The rate of active CD97-positive lymphocytes showed a marked, gradual increase until postoperative day 3 and remained elevated up to day 7 after CPB. OP surgery resulted in moderate alteration in the presence of CD97 on PMN, MC and lymphocytes. The expression of adhesion molecules was similar to CD97 in all leukocyte subsets.

CONCLUSION

The findings about CD97 expression suggest considerable leukocyte activation following coronary bypass with CPB compared to OP surgery. The collected data show that the lymphocytes are highly activated and involved in leukocyte sequestration after CPB. Moreover, the importance of CD97 in CPB-related inflammatory response can be stated.

A cost-effective screening method for pesticide residue analysis in fruits, vegetables, and cereal grains

This paper reports the results of studies performed to investigate the potential of applying thin layer chromatography (TLC) detection in combination with selected extraction and cleanup methods, for providing an alternative cost-effective analytical procedure for screening and confirmation of pesticide residues in plant commodities. The extraction was carried out with ethyl acetate and an on-line extraction method applying an acetone-dichloromethane mixture. The extracts were cleaned up with SX-3 gel, an adsorbent mixture of active carbon, magnesia, and diatomaceous earth, and on silica micro cartridges. The Rf values of 118 pesticides were tested in eleven elution systems with UV, and eight biotest methods and chemical detection reagents. Cabbage, green peas, orange, and tomatoes were selected as representative sample matrices for fruits and vegetables, while maize, rice, and wheat represented cereal grains. As an internal quality control measure, marker compounds were applied on each plate to verify the proper elution and detection conditions. The Rf values varied in the different elution systems. The best separation (widest Rf range) was achieved with silica gel (SG)--ethyl acetate (0.05-0.7), SG--benzene, (0.02-0.7) and reverse phase RP-18 F-254S layer with acetone: methanol: water/30:30:30 (v/v) (0.1-0.8). The relative standard deviation of Rf values (CV(Rf)) within laboratory reproducibility was generally less than 20%, except below 0.2 Rf, where the CVRf rapidly increased with decreasing Rf values. The fungi spore inhibition, chloroplast inhibition, and enzyme inhibition were found most suitable for detection of pesticides primarily for confirming their identity or screening for known substances. Their use for determination of pesticide residues in samples of unknown origin is not recommended.

Application of TLC for confirmation and screening of pesticide residues in fruits, vegetables, and cereal grains: Part 2. Repeatability and reproducibility of Rf and MDQ values

This paper illustrates the effect of major factors influencing the reproducibility of thin layer chromatography (TLC) separation and detection under largely differing environmental and laboratory conditions. The optimum conditions for reproducibility and detection sensitivity was obtained on 20 x 20 cm layer in the retention factor (Rf) range of 0.2-0.7 by applying the sample in spots of 3-4 mm diameter at 2 cm from the edge of the plate. The reproducibility rapidly decreased below Rf = 0.2. Above Rf = 0.2 the within-laboratory reproducibility of 219 pesticides obtained in ethyl acetate silica gel elution system by several laboratories was typically below 10%. The among-laboratories reproducibility of the average retention factors was generally below 12%. The minimum detectable quantities (MDQ) of 219 pesticide residues were determined with nine detection methods. The MDQ values largely varied depending on the mode of detection. Bioassay methods enabled the detection down to 0.1-10 ng, while 20-100 ng could be achieved with the chemical reagents. Higher MDQ values are also reported in order to assist the identification of compounds potentially present. The between-laboratories reproducibility of MDQ values was typically 1-5 MDQmin.

Dynamism of NF-κB and AP-1 Activation in the Signal Transduction of Ischaemic Myocardial Preconditioning

Nuclear factor (NF)-kappaB and activation protein (AP)-1 transcription factors play an important role in the signal transduction of delayed ischaemic preconditioning (PC) leading to myocardial cytoprotection. Because the exact mechanism of the activation of these factors is still not clear, we aimed to monitor the time fluctuation of NF-kappaB and AP-1 induction in an in vivo animal model. Furthermore, we measured the induction rate of these factors using repeated cycles of PC. Following median thoracotomy, anaesthetized animals (24 New Zealand White rabbits) were subjected to ischaemic PC by occlusion of the left anterior descending coronary artery for 5 min. After 10 and 30 min, and 1, 2, 3 and 4 h of reperfusion, tissue samples were taken from the ischaemic myocardium, and the DNA binding activity of the transcription factors was measured with electrophoretic mobility shift assay. A further 12 animals were subjected to 2 x, 3 x or 4 x 5-min ischaemic PC, and after a 30-min or 1-hour reperfusion period, we investigated the possible modulation of NF-kappaB and AP-1 induction. Our results show significant, biphasically increased NF-kappaB activity with peak levels at 30 min and 3 h of reperfusion in preconditioned myocardium. AP-1 increased monophasically, with the peak level at 1 h of reperfusion. Repeated PC stimuli enhanced the activity of both transcription factors analyzed, but there was no significant correlation between the number of cycles and the rate of activation. Our results show that the activation of NF-kappaB and AP-1 have a specific time curve, and the induction of these factors is only slightly influenced by the number of PC cycles.

The effect of different levels of peritoneal CO2 pressure on bleeding time of spleen capsule injury

AIMS

The authors, in contrast to similar injuries with open surgery, had observed spontaneous hemostasis of relatively large spleen capsule injuries during laparoscopic surgery.

METHODS

Standard spleen injuries were carried out in 5 anesthetized mongrel dogs at different CO2 pressures and in open surgery. Bleeding was checked every minute by wiping around the injury but not removing the clot. Bleeding time was measured until no more oozing was detected. At every pressure level 3-3 measurements were done and analyzed. Parenchymal pressure of the spleen and systemic blood pressure were detected with direct catheter implantation.

RESULTS

In open surgery the average bleeding time was 15.2 min; at 5, 15, and 25 mmHg CO2 pressures bleeding times were 12.3, 10.6, and 9.8 min, respectively. The parenchymal pressure of the spleen (5-6 mmHg) rose synchronously with peritoneal pressure, but no significant changes in systemic blood pressure were seen.

CONCLUSION

Peritoneal CO2 pressure may counterweight the parenchymal pressure of the spleen, thus helping hemostasis. There seems to be an inverse proportion between peritoneal pressure and bleeding time. In case of spleen capsule injury during laparoscopic surgery, chances for spontaneous hemostasis are much better compared to open surgery. Attention must be paid to maintain adequate peritoneal pressure.

Is peripheral blood a reliable indicator of acute oxidative stress following heart ischemia and reperfusion?

BACKGROUND

Reactive oxygen species (ROS) play a crucial role in membrane damage in ischemic-reperfusion syndromes. The aim of our work was to determine whether blood samples taken from a peripheral vein are a reliable indicator to reflect the development of oxidative stress following acute heart ischemia and reperfusion.

MATERIAL AND METHODS

In a dog model, the left descending coronary artery (LAD) was occluded for 60 min followed by 60 minutes of reperfusion. The lipid peroxidation marker malondialdehyde (MDA), endogenous antioxidants reduced glutathione (GSH), the activity of superoxide dismutase (SOD) enzyme and the stimulated radical production of isolated neutrophil granulocytes (PMN) were measured simultaneously from the peripheral vein and the coronary sinus before and at the end of the LAD occlusion, and again during reperfusion.

RESULTS

MDA and SOD values increased during reperfusion. At the end of 1 hour the reperfusion changes in the coronary sinus were significant (p<0.05). GSH increased in the femoral vein, but decreased in the coronary sinus. The radical-producing capacity of PMNs decreased by the end of LAD occlusion, and a further significant decrease was measured during reperfusion in the coronary sinus (p<0.01). In the peripheral venous blood samples the decrease of PMN radical production became significant only at 30 minutes of reperfusion (p<0.02), and the earlier difference between the coronary sinus and the femoral vein tended to level out following 60 minutes of reperfusion.

CONCLUSIONS

During early reperfusion following myocardial ischemia coronary sinus blood sampling gives an earlier indication of myocardial damage. At a later phase, peripheral blood samples may also be informative regarding the altered balance between ROS production and the antioxidant capacity.

[Thrombotic thrombocytopenic purpura and systemic lupus erythematous. Three cases presenting simultaneously]

Thrombotic thrombocytopenic purpura (TTP) is a clinical syndrome characterized by microangiopathic hemolytic anemia, thrombocytopenia, fever, neurological symptoms, and renal involvement. The relationship of TTP to systemic lupus erythematosus (SLE) has been recognized in the medical literature since 1939. The differential diagnosis is difficult because both diseases have similar clinical features. The mainstay for recognizing TTP in the context of active SLE is the presence of helmet red cells, marked reticulocytosis, and negative direct Coomb's test. We report three female patients with simultaneous presentation of TTP and SLE. We suggest combined treatment with immunosuppressive therapy and plasma exchange using fresh frozen plasma.

Epidemiology and ethics in the neonatal intensive care unit

There are many ethical dilemmas in the neonatal intensive care unit (NICU), and almost as many solutions as dilemmas. Religion, philosophy, natural law, civil law, criminal law, to name but a few, have each been invoked as a source of authority to resolve the inevitable conflicts arising at the confluence of uncertain outcome, physical pain, and financial expenditure. This article takes a different approach. Here we begin by envisioning what we would most like to know about NICU care that we do not currently know (or at least is not widely known), and then combine "thought experiments" with preliminary "real experiments" to acquire a hypothetical database from which ethics in the NICU can be informed.

The physician as a health care proxy

Many states prohibit patients from appointing their physicians as health care proxies, fearing paternalism and conflict of interest. But the potential for conflict is not unique to physicians, and patients may have compelling reasons to prefer that their doctor make decisions on their behalf. Managing potential conflicts serves patients better than denying them the right to choose who will make health care decisions for them when they are no longer competent.

Methadone dosing, heroin affordability, and the severity of addiction

OBJECTIVES

This study sought to track changes in US heroin prices from 1988 to 1995 and to determine whether changes in the affordability of heroin were associated with changes in the use of heroin by users seeking methadone treatment, as indexed by methadone dose levels.

METHODS

Data on the price of heroin were from the Drug Enforcement Administration; data on methadone doses were from surveys conducted in 1988, 1990, and 1995 of 100 methadone maintenance centers. Multivariable models that controlled for time and city effects were used to ascertain whether clinics in cities where heroin was less expensive had patients receiving higher doses of methadone, which would suggest that these patients had relatively higher physiological levels of opiate addiction owing to increased heroin use.

RESULTS

The amount of pure heroin contained in a $100 (US) purchase has increased on average 3-fold between 1988 and 1995. The average dose of methadone in clinics was positively associated with the affordability of local heroin (P < .01).

CONCLUSIONS

When heroin prices fall, heroin addicts require more methadone (a heroin substitute) to stabilize their addiction--evidence that they are consuming more heroin.

The authority of the clinical ethicist

Mediator? Moral Expert? Or both? "Discourse Ethics" suggests that consensus provides the foundation for defensible moral norms. Thus in building consensus on a moral problem, an ethicist is not just negotiating a compromise but is contributing to the construction of moral rules and principles that have a genuine claim on us. In this way, not only does expertise on a variety of moral positions facilitate mediation, but mediation opens the way to a kind of moral expertise.

A proactive, data-based determination of the standard of medical care in pediatrics

A 3-week-old infant awoke with a fever. He was taken to the doctor who noted that the child was irritable. The doctor took him to the hospital where a resident performed a spinal tap, started an intravenous (IV) line, and ordered antibiotics. The entire drama, from entering the doctor's office to infusion of ampicillin, took 2 hours. The doctor was sued for malpractice. Expert witnesses for the plaintiff testified that he had deviated from the standard of medical care by taking too long to administer antibiotics, which, in their view, ought to have been given within 30 minutes. Expert witnesses for the defense testified that 2 hours to administer antibiotics in this case was within the standard of care. What ought to be the response of the pediatric community to discrepant expert testimony such as this? One possible response is nothing. Lawyers from both sides will find expert medical witnesses who articulate positions favorable to their clients (as they did in this case), and the truth will emerge after vigorous cross-examination. This, we suggest, is inadequate. We believe that some expert opinions can be viewed as better than others. That is, some opinions describe the standard of medical care correctly while other expert opinions are (to put it charitably) idiosyncratic, failing to depict accurately the skill and care ordinarily administered in comparable situations. Currently, jurors are informed about the standard of care by expert witnesses, who rely on their own medical knowledge and experience. However, a huge body of literature demonstrates that recollections of individual experience are inevitably flawed, and flawed in a nonrandom direction (the Monday morning quarterback phenomenon). Consider the infant with meningitis. When experts in pediatric emergency medicine and pediatric infectious diseases (ID) were asked about the median time from emergency room (ER) presentation to administration of antibiotics in a child with suspected meningitis, their opinions were wrong and slanted toward the outcome known to be desired (namely, a shorter elapsed time). ER physicians (median estimated time to antibiotic administration [AB-TIME] = 46 minutes) and ID physicians (median estimated AB-TIME = 80 minutes) consistently underestimated the actual median value of AB-TIME determined by chart review (120 minutes). From the judicial perspective such potential flaws in expert testimony are assumed to be equally distributed among experts. All admissible evidence is a priori of equal weight until a jury decides otherwise. The standard of medical care is created anew by expert testimony in each individual case, disappearing, like Brigadoon, upon resolution of the dispute. However, to anyone but a lawyer, the standard of medical care must exist as something outside the courtroom testimony of experts, and if it does exist, it should be easily described so that expert testimony can be judged more (or less) accurate in depicting it. We contend that medical care is not a single behavior that conforms to or deviates from an idiosyncratic and retrospectively determined standard, but rather a distribution of behaviors in response to a variety of medical circumstances. For a given scenario, each of several possible responses can be ascribed a relative frequency based on empirical data, and the consequent normal curve depicts the totality of medical care. Substandard care then falls out neatly as behaviors lying outside the large majority of cases. Juries would be empowered (as they are currently) to determine exactly where on this curve substandard care lies, but at least the debate would share the same description of reality. Recent US Supreme Court guidelines regarding expert testimony provide an opportunity to expand the use of databases in medical negligence cases. The Court restricted expert testimony to "scientific knowledge ... based on generating hypotheses and testing them to see if they can be falsified ... (ABSTRACT TRUNCATED)

[Surgical trauma induced by laparoscopic cholecystectomy]

The objective demonstration of improved postoperative recovery suggests that surgical injury induced by the laparoscopic approach is less intense than that after open surgery. Forty-two patients diagnosed as having noncomplicated gallstones were studied prospectively. They were operated on by laparoscopy (LC, n = 21) or open surgery (OC, n = 21). Both surgical procedures induced significant changes of investigated parameters (acute-phase response, free radical mediated reactions, neutrophil functions). Comparison of the results of the two cholecystectomy techniques showed that laparoscopic cholecystectomy induced a significantly less intense acute-phase response, a more attenuated oxidative stress characterising by free radical mediated reactions and that is less disruptive to neutrophil function. The results and the data from the literature suggest that surgical injury causing by the laparoscopic cholecystectomy is less intense than that after open cholecystectomy, which can explain partially the better clinical outcome following laparoscopic versus open procedure.

The values of detection of free radical mediated reactions in patients

The peroxidative processes and individual antioxidant protection were measured in patients with different cardiovascular diseases. We concluded that monitoring of this system we were able to detect not only the actual changes of lipid peroxidation and antioxidant defence mechanisms, but additionally the therapeutic efficacy of the treatment.

Monitoring of plasma total antioxidant status in different diseases

The pathological increase of oxygen free radical generation has already been recognised in more than one hundred diseases. To gain information about the consequences of oxidative stress the investigation of plasma antioxidants seems to be plausible. In our study we used a new kit (RANDOX, England) for measurement of total antioxidant status (TAS) to determine whether it has diagnostic value in comparison with our earlier results of measuring other parameters of oxidative stress in the following diseases: i./In the group of patients with ischemic heart disease (n = 19) the TAS elevated from 1.08 +/- 0.13 to 1.16 +/- 0.11 mM after 2 weeks of cardioprotective drug administration showing the beneficial effect of drug treatment. ii./In the group of patients with essential hypertension (n = 47) its values were below the normal range (1.11 +/- 0.15 mM) at the time of the first investigation and increased gradually following antihypertensive treatment. iii./The changes of TAS values of patients who underwent open (n = 21) or laparoscopic (n = 21) cholecystectomy indicated the less surgical trauma following laparoscopic procedures. Our results suggest that determination of TAS is a valuable and reproducible method to detect the actual antioxidant status in patients.

Inflammatory mediators and surgical trauma regarding laparoscopic access: acute phase response

Numerous studies have tried to compare different aspects of patient response to laparoscopic cholecystectomy (LC) versus open cholecystectomy (OC). Our study focused on the acute phase response in order to clarify the better patient recovery following LC. Sixteen patients scheduled for elective cholecystectomy were equally allocated into groups of OC and LC. Blood samples were collected before and for four days after the procedures. Levels of interleukin 6 (IL-6) and C-reactive protein (CRP) were determined by ELISA technique. IL-6 value increased ten fold on the first postoperative day (52.8 pg/ml) in the OC group with a return to baseline value by the fourth postoperative day. In contrast a moderate increase postoperatively (12.1 pg/ml) with a fast normalisation of IL-6 value by the second postoperative day was noted in LC group. A similar pattern was observed in the CRP level. CRP peaked to 84.1 mg/l by the second follow-up day after OC, while only an insignificant rise to 52.7 mg/l was registered in the LC group with again a faster return to baseline value. The marked contrast between the two groups with regard to IL-6 and CRP changes clearly underlines a diminished acute phase response following LC, which verifies LC as probably a less traumatic procedure.

The effects of bisaramil and antiarrhythmics on free radical generation of isolated neutrophil granulocytes

The aim of this study was to investigate the effect of bisaramil--an antiarrhythmic drug under clinical trials--on free radical generation of isolated polymorph neutrophil granulocytes (PMN) and to compare its activity with well-known antiarrhythmics. PMNs were isolated from healthy beagle dogs, and superoxide radical generation was induced by phorbol-myristate-acetate. Free radical generation capacity of stimulated PMNs were measured. Bisaramil exerted a concentration dependent inhibitory effect on stimulated free radical generation. At the investigated concentration range of the antiarrhythmics only propafenon, mexiletine and diltiazem showed similar activity as bisaramil, but clear concentration dependency could not be seen in any of the cases. According to the results of this study inhibition of stimulated free radical production by isolated PMNs can not be closely related merely to either membrane stabilizing or Ca-antagonistic activity of drugs. In vitro inhibitory action of bisaramil on free radical generation indicates a possible cardioprotective effect existing independently of its antiarrhythmic one. This observation may be important in outlining the range of clinical indications of bisaramil as it may also be useful in the treatment of reperfusion injury.

Inflammatory mediators and surgical trauma regarding laparoscopic access: free radical mediated reactions

In this prospective study the free radical mediated reactions, the changes of endogenous antioxidant defense mechanism and activation of leukocytes were measured from the blood of patients undergoing elective cholecystectomy because of symptomatic cholecystolithiasis. The patients were randomised into two groups. Group one contained 21 patients treated by open cholecystectomy(OC). Group two consisted of 21 patients treated by laparoscopic cholecystectomy (LC). Both groups had similar patient characteristics. Patients with acute cholecystitis, pancreatitis, choledocholithiasis or other disease were excluded. Values from patients in both groups were compared. The measured biochemical parameters are the following: malondialdehyde (MDA) as a marker of the free radical induced lipid peroxidations, reduced and oxidised glutathione (GSH-GSSG), as endogenous scavengers as well as markers of oxidative stress and myeloperoxidase activity (MPO) of leukocytes. The results showed significantly lower values of postoperatively measured MDA, GSH-GSSG, and MPO activity of leukocytes in patients with laparoscopic cholecystectomy, indicating a lesser stress response and tissue trauma in this group of patients. The results correspond to the favourable results of most other trials evaluating clinical aspect of LC.

Inflammatory mediators and surgical trauma regarding laparoscopic access: neutrophil function

Polymorphonuclear leukocytes (PMN) are well recognised as being the principal cells in the inflammatory response reaction. The current investigation was designed to evaluate the stimulated state of neutrophils in patients undergoing open (OC) and laparoscopic cholecystectomy (LC). The superoxide radical generation of isolated PMN and its lag time, and PMN elastase were measured in peripheral venous blood samples collected from 42 patients. The observation period started on the day of hospital admission and ended on the 5 th day. Our results showed that although there were no characteristic changes in the superoxide radical production of PMN in the LC group, we found a marked depletion already by the first day in OC group which persisted during the whole observation period. There was an elevation of PMN elastase on the first postoperative day in both groups, but in the laparoscopically operated patients it decreased considerably on the 3rd postoperative day while in the OC group it maintained a high level. The same discrepancy was present between the two groups on the 5th day. Decreased free radical production of isolated PMN may reflect depleted neutrophil functional state, while changes of PMN elastase indicates increased harmful potential. These data suggest the differences in neutrophil activation between the two groups can be partially responsible for the better outcome in patients operated by laparoscopic cholecystectomy.

Community equipoise and the architecture of clinical research

We have argued for a revision of Freedman's concept of clinical equipoise to a broader sense of community that includes physicians and patients. Community equipoise is an essential condition for physicians and patients to answer these questions: Should there be a trial? If so, what kind? We have argued that community equipoise exists because of changes in the knowledge gap between physicians and patients and in the moral justification of medical decision-making. Finally, we have briefly examined the social aspect of medical knowledge to argue that it necessarily includes patients and their values. In effect, community equipoise is not so much an effort to change things, as to explain the way they are. We suggest that patients can participate at a number of points in the process of drug study design and approval: (1) study design with attention to criteria for eligibility, endpoints, and choice of methodology, (2) research review and approval with attention to enhancing community participation in IRB activities, and (3) interim evaluation of ongoing studies with attention to including patient and clinician values in the decisionmaking. Clinical trials are a tool. Like a gun or a bomb or the very drugs they test, they are powerful tools to achieve their ends. The issue is how to properly use such tools as randomization, placebo controls, endpoints, and eligibility. To the extent that community equipoise exists prior to a trial, it means that clinical researchers and patients have collectively addressed the risk and benefit trade-offs that govern the decision to start and to end a clinical trial. In this way, trials can be both valid and valued.

Physicians' experience with allegations of medical malpractice in the neonatal intensive care unit

OBJECTIVE

To assess the personal experience of all practitioners of neonatal intensive care unit (NICU) medicine in the United States with the medical malpractice system; in particular, to assess the circumstances of malpractice allegations in which they themselves had personal experience, and to extrapolate from their individual experiences to the field of neonatology in general.

DESIGN

Written survey of all MDs practicing NICU medicine in the US.

PARTICIPANTS

Two thousand four hundred ninety-eight NICU physicians as determined from three sources: a) the American Board of Medical Specialists; b) the American Academy of Pediatrics Section of Neonatal/Perinatal Medicine; and c) a listing of neonatologists provided by Ross Laboratories.

MAIN OUTCOME MEASURES

Responses to survey questions.

RESULTS

We received 1813 responses, representing approximately 75% of all physicians practicing NICU medicine in the US. Overall, 43% of respondents had experienced at least one claim of malpractice against them. The probability of a malpractice allegation increased with years in practice, from approximately 20% for NICU physicians in practice </=5 years (65/337), to approximately 60% for NICU physicians in practice >15 years (276/469). Men and women were equally likely to have been sued, accounting for years in practice. Physicians practicing in community NICUs were more likely to be sued than those in university settings. On a scale of 1 to 4 (4 being most reasonable) the median assessment of the reasonableness of malpractice allegations was 1, mean 1.2. On a scale of 1 to 4 (4 being the highest) the median assessment of effectiveness of the current system in identifying true malpractice was 1, mean 1.4. The respondents believed that approximately 80% of malpractice allegations were inappropriate; conversely, they believed that approximately 80% of true medical malpractice escaped detection. On a scale of 1 to 4 (4 being the highest), the median assessment of the detrimental effect of the present malpractice system on health care was 4, mean 3.4.

CONCLUSIONS

Most NICU physicians will be sued if they practice long enough. In this context, efforts to use malpractice claims to seek out evildoers (such as underlie the National Practitioners Data Bank) appear ill-conceived. Similarly, exhortations for physicians to become either more educated or more sensitive are unlikely to reduce malpractice claims. Our data suggest that malpractice in the NICU appears to function more like a lottery than like a mechanism for either quality assurance or just retribution.

Cardioprotection during heart ischemia-reperfusion

Oxygen reactive species play a significant role in reperfusion tissue damages. In this study we aimed to investigate the mechanisms of injury regarding changes of neutrophil function. In our experiments the left descending coronary artery (LAD) was ligated in Beagle dogs for 1 hour followed by one hour reperfusion. Animals were divided into two groups: Group I. dogs (n = 10) served as control: Group II. the animals (n = 10) were treated by cardioprotective drug Bisaramil. Peripheral blood samples were taken for neutrophil isolation before operation and subsequent reperfusion (5 min, 1 hour). The stimulated superoxide radical generating capacity of polymorphonuclear leukocytes (PMN) was measured. The lipid peroxidation (MDA), amount of reduced glutathione (GSH) and activity of superoxide dismutase (SOD) were measured in non-ischemic and ischemic parts of left ventricle. There was no significant changes either in control or in treated animals in respect to changes of neutrophil radical production after one hour LAD ligature, however there was a significant discrepancy (p < 0.001) between control and treated animals following a 1 hour reperfusion. The values of MDA in the ischemic-area increased characteristically in the Group I. parallel with decrease of scavenger GSH and SOD. In contrast in Group II., where depleted PMN radical production was observed endogenous scavengers were preserved on a higher level. In summary we can conclude that diminished superoxide radical production of circulating neutrophils during reperfusion has beneficial effects on tissue injury caused especially by free radicals.

The relationship between physician behaviors and blood gas values in the first hours of life--implications for "standards" of medical care for infants with respiratory distress

It is standard practice for physicians to use blood gas (BG) evaluations when evaluating neonates with respiratory distress. In this study we addressed two questions: (1) What is the distribution of BG values in a population of infants receiving BG evaluation in the first 4 hours of life; and (2) How does the behavior of physicians correlate with BG values in these infants? We discuss the implications of our findings for claims about "standards" of medical care for newborn infants with respiratory distress. We reviewed medical records for 226 infants with birthweight > 2000 grams who were not intubated at the time of first BG determination. For 199 arterial samples, mean values were pH = 7.31 +/- 0.9 (SD); PaCO2 = 38.5 +/- 11.9 torr; PaO2 = 104 +/- 52 torr; and base excess (BE) = -6.5 +/- 3.8 mEq/L. These values did not differ significantly from previously published data for normal term infants without respiratory distress. However, the a/A ratio (0.45 +/- 0.19) for patients in our distressed population was significantly lower than reported for normal infants (0.65 +/- 0.10). For 186 infants admitted directly to our Newborn Intensive Care Unit, the elapsed time from birth to BG 1 was 1.07 +/- 0.64 hours. This value did not vary significantly as a function of severity of illness, assessed by pH, PaCO2, PaO2, a/A ratio, or BE. No blood gas parameter was simultaneously sensitive and specific for predicting subsequent mechanical ventilation. PaCo2 1 > 80 torr was associated with subsequent mechanical ventilation in 4 of 4 infants; however, the positive predictive value of PaCO2 1 was < 50% for levels below 80 torr, and only 4 of 22 infants eventually intubated were identified by a value of PaCO2 1 > 80 torr. The power of "abnormal" values of PaO2, a/A ratio, pH, or BE to predict subsequent intubation was even lower than PaCO2. Jurors in medical malpractice cases are instructed to define negligence as a deviation from the "skill and care ordinarily used in similar cases," and to determine the existence or absence of negligence guided by the testimony of "expert" witnesses. Recognizing that anecdotal recall of experience, even by "experts," may be inaccurate and is often systematically biased (the "Monday morning quarterback" phenomenon), we propose that the testimony of expert witnesses ought to conform, whenever possible, to a data-based description of medical care that actually is "ordinary used in similar circumstances". Our current observations suggest that (1) expert opinions of the "standard" to evaluate neonatal respiratory distress with a BG sample should reflect that the time scale is 1 to 2 hours, not 10 to 20 minutes; and (2) expert opinions that "abnormal" BG values either "require" or "preclude" intubation for most newborn infants with respiratory distress find little support in data. Clinical observation, not BG values, appears to be the most powerful "standard" by which physicians determine whether to initiate mechanical ventilation for newborn infants with respiratory distress.

Reassessing medical students' willingness to treat HIV-infected patients

BACKGROUND

Past research has demonstrated that some physicians do not feel obligated to care for patients infected with the human immunodeficiency virus (HIV). This study sought to characterize the attitudes that affect medical students' willingness to treat HIV-infected patients and to determine which attitudes are most amenable to intervention.

METHOD

All 414 matriculating medical students at three Chicago schools were surveyed in 1994. After reliability-testing the attitudinal scales, the authors created a predictive model by using multiple regression analysis.

RESULTS

A total of 297 (72%) of the matriculating students responded. Ninety-two percent of the students agreed that patients with HIV would be welcome in their medical practices. As in past studies, a strong sense of professional obligation was associated with willingness to treat, and fear of infection and homophobia were associated with decreased willingness to treat. The authors' measure of concern about social stigma was also associated with decreased willingness. Together, these factors accounted for 53% of the variance in the Willingness to Treat scale.

CONCLUSION

In addition to confirming the predictors found in previous studies, this study demonstrated that perceived social stigma is a measurable predictor of decreased willingness to treat (with the understanding that willingness to treat is influenced by both personal and social factors). A comprehensive approach, not only in curriculum design but also in admission and policy, might better prepare students to treat HIV-infected patients.