Modelling of Neuronal Ceroid Lipofuscinosis Type 2 in Dictyostelium discoideum Suggests That Cytopathological Outcomes Result from Altered TOR Signalling

The neuronal ceroid lipofuscinoses comprise a group of neurodegenerative disorders with similar clinical manifestations whose precise mechanisms of disease are presently unknown. We created multiple cell lines each with different levels of reduction of expression of the gene coding for the type 2 variant of the disease, Tripeptidyl peptidase (Tpp1), in the cellular slime mould Dictyostelium discoideum. Knocking down Tpp1 in Dictyostelium resulted in the accumulation of autofluorescent material, a characteristic trait of Batten disease. Phenotypic characterisation of the mutants revealed phenotypic deficiencies in growth and development, whilst endocytic uptake of nutrients was enhanced. Furthermore, the severity of the phenotypes correlated with the expression levels of Tpp1. We propose that the phenotypic defects are due to altered Target of Rapamycin (TOR) signalling. We show that treatment of wild type Dictyostelium cells with rapamycin (a specific TOR complex inhibitor) or antisense inhibition of expression of Rheb (Ras homologue enriched in the brain) (an upstream TOR complex activator) phenocopied the Tpp1 mutants. We also show that overexpression of Rheb rescued the defects caused by antisense inhibition of Tpp1. These results suggest that the TOR signalling pathway is responsible for the cytopathological outcomes in the Dictyostelium Tpp1 model of Batten disease.

Dictyostelium, a microbial model for brain disease

BACKGROUND

Most neurodegenerative diseases are associated with mitochondrial dysfunction. In humans, mutations in mitochondrial genes result in a range of phenotypic outcomes which do not correlate well with the underlying genetic cause. Other neurodegenerative diseases are caused by mutations that affect the function and trafficking of lysosomes, endosomes and autophagosomes. Many of the complexities of these human diseases can be avoided by studying them in the simple eukaryotic model Dictyostelium discoideum.

SCOPE OF REVIEW

This review describes research using Dictyostelium to study cytopathological pathways underlying a variety of neurodegenerative diseases including mitochondrial, lysosomal and vesicle trafficking disorders.

MAJOR CONCLUSIONS

Generalised mitochondrial respiratory deficiencies in Dictyostelium produce a consistent pattern of defective phenotypes that are caused by chronic activation of a cellular energy sensor AMPK (AMP-activated protein kinase) and not ATP deficiency per se. Surprisingly, when individual subunits of Complex I are knocked out, both AMPK-dependent and AMPK-independent, subunit-specific phenotypes are observed. Many nonmitochondrial proteins associated with neurological disorders have homologues in Dictyostelium and are associated with the function and trafficking of lysosomes and endosomes. Conversely, some genes associated with neurodegenerative disorders do not have homologues in Dictyostelium and this provides a unique avenue for studying these mutated proteins in the absence of endogeneous protein.

GENERAL SIGNIFICANCE

Using the Dictyostelium model we have gained insights into the sublethal cytopathological pathways whose dysregulation contributes to phenotypic outcomes in neurodegenerative disease. This work is beginning to distinguish correlation, cause and effect in the complex network of cross talk between the various organelles involved. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.

Mitral valve repair for ischemic mitral regurgitation: review of current techniques

INTRODUCTION

Ischemic mitral regurgitation can be defined as moderate to severe mitral leak precipitated by acute myocardial infarction. Valve repair is now the procedure of choice, but some cases can pose difficult anatomy. This review will illustrate current techniques for repairing complex ischemic mitral regurgitation.

METHODS

Most patients with ischemic mitral regurgitation have predominant annular dilatation at the posterior commissure and require only ring annuloplasty. Full rigid rings are used preferentially. With leaflet tethering, adjunctive autologous pericardial patches are effective in restoring leaflet coaptation. If papillary muscle elongation or rupture occurs, Gore-Tex artificial chordal replacement performs well. With ischemic mitral regurgitation accompanying posterior ventricular aneurysms, standard trans-atrial mitral repair provides the best results, with associated aneurysms being repaired concurrently.

RESULTS

Surgical approaches and technical outcomes of mitral repair in ischemic mitral regurgitation are illustrated in 5 patients using operative images and echocardiograms. Each method is illustrated, including ring annuloplasty, pericardial leaflet augmentation, artificial chordal replacement, and ventricular aneurysm repair. Using these techniques, virtually all ischemic mitral regurgitation can be repaired, with consequential patient benefits, even in the most complex anatomy.

CONCLUSIONS

Ischemic mitral regurgitation has been shown to have better outcomes when managed with valve repair. Using combinations of annular, leaflet, and chordal procedures, even complex ischemic mitral regurgitation can undergo autologous reconstruction with excellent long-term results.

MidA is a putative methyltransferase that is required for mitochondrial complex I function

Dictyostelium and human MidA are homologous proteins that belong to a family of proteins of unknown function called DUF185. Using yeast two-hybrid screening and pull-down experiments, we showed that both proteins interact with the mitochondrial complex I subunit NDUFS2. Consistent with this, Dictyostelium cells lacking MidA showed a specific defect in complex I activity, and knockdown of human MidA in HEK293T cells resulted in reduced levels of assembled complex I. These results indicate a role for MidA in complex I assembly or stability. A structural bioinformatics analysis suggested the presence of a methyltransferase domain; this was further supported by site-directed mutagenesis of specific residues from the putative catalytic site. Interestingly, this complex I deficiency in a Dictyostelium midA− mutant causes a complex phenotypic outcome, which includes phototaxis and thermotaxis defects. We found that these aspects of the phenotype are mediated by a chronic activation of AMPK, revealing a possible role of AMPK signaling in complex I cytopathology.

Legionella pneumophila multiplication is enhanced by chronic AMPK signalling in mitochondrially diseased Dictyostelium cells

Human patients with mitochondrial diseases are more susceptible to bacterial infections, particularly of the respiratory tract. To investigate the susceptibility of mitochondrially diseased cells to an intracellular bacterial respiratory pathogen, we exploited the advantages of Dictyostelium discoideum as an established model for mitochondrial disease and for Legionella pneumophila pathogenesis. Legionella infection of macrophages involves recruitment of mitochondria to the Legionella-containing phagosome. We confirm here that this also occurs in Dictyostelium and investigate the effect of mitochondrial dysfunction on host cell susceptibility to Legionella. In mitochondrially diseased Dictyostelium strains, the pathogen was taken up at normal rates, but it grew faster and reached counts that were twofold higher than in the wild-type host. We reported previously that other mitochondrial disease phenotypes for Dictyostelium are the result of the activity of an energy-sensing cellular alarm protein, AMP-activated protein kinase (AMPK). Here, we show that the increased ability of mitochondrially diseased cells to support Legionella proliferation is suppressed by antisense-inhibiting expression of the catalytic AMPKalpha subunit. Conversely, mitochondrial dysfunction is phenocopied, and intracellular Legionella growth is enhanced, by overexpressing an active form of AMPKalpha in otherwise normal cells. These results indicate that AMPK signalling in response to mitochondrial dysfunction enhances Legionella proliferation in host cells.

Dichotomy of food and inhalant allergen sensitization in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EE) is an emerging condition where patients commonly present with symptoms of gastroesophageal reflux disease and fail to respond adequately to anti-reflux therapy. Food allergy is currently recognized as the main immunological cause of EE; recent evidence suggests an etiological role for inhalant allergens. The presence of EE appears to be associated with other atopic illnesses.

OBJECTIVES

To report the sensitization profile of both food and inhalant allergens in our EE patient cohort in relation to age, and to profile the prevalence of other allergic conditions in patients with EE.

METHOD

The study prospectively analyzed allergen sensitization profiles using skin prick tests to common food allergens and inhalant allergens in 45 children with EE. Patch testing to common food allergens was performed on 33 patients in the same cohort. Comorbidity of atopic eczema, asthma, allergic rhinitis and anaphylaxis were obtained from patient history.

RESULTS

Younger patients with EE showed more IgE and patch sensitization to foods while older patients showed greater IgE sensitization to inhalant allergens. The prevalence of atopic eczema, allergic rhinitis and asthma was significantly increased in our EE cohort compared with the general Australian population. A total of 24% of our cohort of patients with EE had a history of anaphylaxis.

CONCLUSION

In children with EE, the sensitization to inhalant allergens increases with age, particularly after 4 years. Also, specific enquiry about severe food reactions in patients presenting with EE is strongly recommended as it appears this patient group has a high incidence of anaphylaxis.

Serine proteases, their inhibitors and allergy

This paper reviews four serine protease inhibitors and three protease gene defects that are associated with allergic conditions, suggesting an important role for these genes and their products in the development of allergy. Serine protease inhibitors may have a therapeutic potential in the treatment of allergy.

Grandparents use of new communication technologies in a European perspective

This study examined the pattern of use of different forms of contact between grandparents and grandchildren, and especially the use of new technologies (SMS, e-mail) and factors affecting this. Questionnaire data are reported from 408 grandparents in the UK, Spain, Finland and Estonia, regarding contacts with grandchildren mostly in the 10-15-year age range. Face-to-face contact remained the most frequent mean, followed closely by landline telephone; there was moderate use of mobile phones, and many used letters/cards occasionally; and a minority used SMS and e-mails (about one-half to one-third of those with mobile phones, and networked computers, respectively). When contacting grandchildren, most grandparents accumulate different forms of contact, but others compensate some forms of contact. There were no differences by age of grandparent, but grandmothers made more use of e-mail than grandfathers, as did more highly educated grandparents and those with older grandchildren. Implications for use of Information and Communication Technology by older people are discussed.

Genetic factors contribute to bleeding after cardiac surgery

BACKGROUND

Postoperative bleeding remains a common, serious problem for cardiac surgery patients, with striking inter-patient variability poorly explained by clinical, procedural, and biological markers.

OBJECTIVE

We tested the hypothesis that genetic polymorphisms of coagulation proteins and platelet glycoproteins are associated with bleeding after cardiac surgery.

PATIENTS/METHODS

Seven hundred and eighty patients undergoing aortocoronary surgery with cardiopulmonary bypass were studied. Clinical covariates previously associated with bleeding were recorded and DNA isolated from preoperative blood. Matrix Assisted Laser Desorption/Ionization, Time-Of-Flight (MALDI-TOF) mass spectroscopy or polymerase chain reaction were used for genotype analysis. Multivariable linear regression modeling, including all genetic main effects and two-way gene-gene interactions, related clinical and genetic predictors to bleeding from the thorax and mediastinum.

RESULTS

Nineteen candidate polymorphisms were assessed; seven [GPIaIIa-52C>T and 807C>T, GPIb alpha 524C>T, tissue factor-603A>G, prothrombin 20210G>A, tissue factor pathway inhibitor-399C>T, and angiotensin converting enzyme (ACE) deletion/insertion] demonstrate significant association with bleeding (P < 0.01). Adding genetic to clinical predictors results improves the model, doubling overall ability to predict bleeding (P < 0.01).

CONCLUSIONS

We identified seven genetic polymorphisms associated with bleeding after cardiac surgery. Genetic factors appear primarily independent of, and explain at least as much variation in bleeding as clinical covariates; combining genetic and clinical factors double our ability to predict bleeding after cardiac surgery. Accounting for genotype may be necessary when stratifying risk of bleeding after cardiac surgery.

Site-specific PEGylation of hemoglobin at Cys-93(beta): correlation between the colligative properties of the PEGylated protein and the length of the conjugated PEG chain

Increasing the molecular size of acellular hemoglobin (Hb) has been proposed as an approach to reduce its undesirable vasoactive properties. The finding that bovine Hb surface decorated with about 10 copies of PEG5K per tetramer is vasoactive provides support for this concept. The PEGylated bovine Hb has a strikingly larger molecular radius than HbA (1). The colligative properties of the PEGylated bovine Hb are distinct from those of HbA and even polymerized Hb, suggesting a role for the colligative properties of PEGylated Hb in neutralizing the vasoactivity of acellular Hb. To correlate the colligative properties of surface-decorated Hb with the mass of the PEG attached and also its vasoactivity, we have developed a new maleimide-based protocol for the site-specific conjugation of PEG to Hb, taking advantage of the unusually high reactivity of Cys-93(beta) of oxy HbA and the high reactivity of the maleimide to protein thiols. PEG chains of 5, 10, and 20 kDa have been functionalized at one of their hydroxyl groups with a maleidophenyl moiety through a carbamate linkage and used to conjugate the PEG chains at the beta-93 Cys of HbA to generate PEGylated Hbs carrying two copies of PEG (of varying chain length) per tetramer. Homogeneous preparations of (SP-PEG5K)(2)-HbA, (SP-PEG10K)(2)-HbA, and (SP-PEG20K)(2)-HbA have been isolated by ion exchange chromatography. The oxygen affinity of Hb is increased slightly on PEGylation, but the length of the PEG-chain had very little additional influence on the O(2) affinity. Both the hydrodynamic volume and the molecular radius of the Hb increased on surface decoration with PEG and exhibited a linear correlation with the mass of the PEG chain attached. On the other hand, both the viscosity and the colloidal osmotic pressure (COP) of the PEGylated Hbs exhibited an exponential increase with the increase in PEG chain length. In contrast to the molecular volume, viscosity, and COP, the vasoactivity of the PEGylated Hbs was not a direct correlate of the PEG chain length. There appeared to be a threshold for the PEG chain length beyond which the protection against vasoactivity is decreased. These results suggest that the modulation of the vasoactivity of Hb by PEG could be a function of the surface shielding afforded by the PEG, the latter being a function of the disposition of the PEG chain on the protein surface, which in turn is a function of the length of the PEG chain. Thus, the biochemically homogeneous PEGylated Hbs described in the present study, surface-decorated with PEG chains of appropriate size, could serve as potential candidates for Hb-based oxygen carriers.

Food allergy in children

Food allergies are increasing in prevalence and as a disease burden throughout the world, however they seem to increasingly affect countries with a formerly low prevalence. Consideration and diagnosis of food allergies are important as it has ramifications that affect a child's diet, care at school and home and is recognised to be associated with anxiety of parents, family and care takers. Food allergies vary significantly between countries, however nut allergies appear to be widely associated with serious reactions and death. The value of specific food immunoglobulin E (IgE) and skin prick tests (SPT) has been extensively analysed in children in recent years and can provide very useful information in an appropriately selected population. Diagnosis may require formal challenges to confirm a genuine allergic reaction condition rather than an intolerance reaction due to other mechanisms. The medical care of a food allergic child requires concurrent dietary advice and management, risk avoidance and emergency management plans. Reintroduction of foods occurs when the risk profile is appropriate based mainly on the predictive information obtained by SPTs and specific IgE levels. Fortunately allergies to egg and milk resolve by 3-5 years in about 80% of children. There have been some recent advances in immunotherapeutic approaches to food allergy although this has not translated to success in human treatment to date.

Prospective randomized trial of normothermic versus hypothermic cardiopulmonary bypass on cognitive function after coronary artery bypass graft surgery

BACKGROUND

Despite significant advances in cardiopulmonary bypass (CPB) technology, surgical techniques, and anesthetic management, central nervous system complications occur in a large percentage of patients undergoing surgery requiring CPB. Many centers are switching to normothermic CPB because of shorter CPB and operating room times and improved myocardial protection. The authors hypothesized that, compared with normothermia, hypothermic CPB would result in superior neurologic and neurocognitive function after coronary artery bypass graft surgery.

METHODS

Three hundred patients undergoing elective coronary artery bypass graft surgery were prospectively enrolled and randomly assigned to either normothermic (35.5-36.5 degrees C) or hypothermic (28-30 degrees C) CPB. A battery of neurocognitive tests was performed preoperatively and at 6 weeks after surgery. Four distinct cognitive domains were identified and standardized using factor analysis and were then compared on a continuous scale.

RESULTS

Two hundred twenty-seven patients participated in 6-week follow-up testing. There were no differences in neurologic or neurocognitive outcomes between normothermic and hypothermic groups in multivariable models, adjusting for covariable effects of baseline cognitive function, age, and years of education, as well as interaction of these with temperature treatment.

CONCLUSIONS

Hypothermic CPB does not provide additional central nervous system protection in adult cardiac surgical patients who were maintained at either 30 or 35 degrees C during CPB.

Report of a substudy on warm versus cold cardiopulmonary bypass: changes in creatinine clearance

BACKGROUND

Renal dysfunction remains a major complication of cardiac operations. There is concern regarding the possibility of increased renal injury during warm cardiopulmonary bypass (CPB). Therefore, we tested the hypothesis that warm CPB is associated with a greater reduction in creatinine clearance after cardiac surgery than hypothermic CPB.

METHODS

We randomly assigned 300 patients who had elective coronary artery bypass grafting to warm (35.5 to 36.5 degrees C) or cold (28 degrees C to 30 degrees C) CPB. Preoperative and peak postoperative serum creatinine values were recorded. Creatinine clearance was estimated using the Cockroft Gault equation. Univariate and multivariable analyses were performed to test the association of CPB temperature and perioperative change in creatinine clearance.

RESULTS

Demographic variables were similar between groups. Multivariable analysis did not confirm an association between temperature and change in creatinine clearance (p = 0.87).

CONCLUSIONS

We did not confirm an association between warm CPB and increased renal dysfunction after cardiac operations compared with hypothermic CPB.

Leucocyte populations in respiratory syncytial virus-induced bronchiolitis

OBJECTIVES

To enumerate the cellular composition of the airways in infants with acute bronchiolitis.

METHODOLOGY

Cells were obtained by airway lavage from the upper and lower airway and the peripheral blood of infants with respiratory syncytial virus (RSV)+ bronchiolitis, RSV- bronchiolitis and age-matched controls.

RESULTS

Neutrophils are the predominant cells present in the upper and lower airway. Neutrophils are present at a higher number/unit volume in the airway than in the peripheral blood.

CONCLUSIONS

Neutrophils, being the dominant cellular infiltrate into the airway, are likely to contribute to the pathophysiology of bronchiolitis. Therapies targeted at limiting neutrophil influx or neutrophil-mediated damage in the airway may have a therapeutic role.

Depressive symptoms and outcome of coronary artery bypass grafting

BACKGROUND

Depressive symptoms are an independent risk factor for outcome in patients with cardiac disease, but their effect on outcome among patients undergoing coronary artery bypass grafting is not well understood.

OBJECTIVES

To determine whether or not clinical variables including length of stay, readmission rates, and mortality are related to patients' level of depressive symptoms before and after coronary artery bypass grafting.

METHODS

An observational, longitudinal design was used. The Medical Outcomes Study 36-item short-form health survey was used to collect data on depressive symptoms in 416 patients undergoing coronary artery bypass grafting. The distribution of depressive symptoms was correlated with length of stay after the procedure, readmission, and mortality.

RESULTS

The level of depressive symptoms before coronary artery bypass grafting correlated with the level of depressive symptoms at 6 weeks follow-up, both for the individual items "feeling down in the dumps" (r = 0.24, P = .009) and "feeling downhearted" (r = 0.36, P < .001) and for the overall score on the Mental Health scale (r = 0.40, P < .001). Feeling down in the dumps (P = .007) and overall scores on the Mental Health scale (P = .02) were significantly related to readmission within 6 months.

CONCLUSIONS

Higher levels of depressive symptoms before coronary artery bypass grafting are related to higher hospital readmission rates 6 months after the procedure. Nurses can play a pivotal role in determining which patients require evaluation, educating patients, and initiating effective treatment, which may prevent readmission related to depressive symptoms.

Depressive symptoms and outcome of coronary artery bypass grafting

BACKGROUND: Depressive symptoms are an independent risk factor for outcome in patients with cardiac disease, but their effect on outcome among patients undergoing coronary artery bypass grafting is not well understood. OBJECTIVES: To determine whether or not clinical variables including length of stay, readmission rates, and mortality are related to patients' level of depressive symptoms before and after coronary artery bypass grafting. METHODS: An observational, longitudinal design was used. The Medical Outcomes Study 36-item short-form health survey was used to collect data on depressive symptoms in 416 patients undergoing coronary artery bypass grafting. The distribution of depressive symptoms was correlated with length of stay after the procedure, readmission, and mortality. RESULTS: The level of depressive symptoms before coronary artery bypass grafting correlated with the level of depressive symptoms at 6 weeks follow-up, both for the individual items "feeling down in the dumps" (r = 0.24, P = .009) and "feeling downhearted" (r = 0.36, P &lt; .001) and for the overall score on the Mental Health scale (r = 0.40, P &lt; .001). Feeling down in the dumps (P = .007) and overall scores on the Mental Health scale (P = .02) were significantly related to readmission within 6 months. CONCLUSIONS: Higher levels of depressive symptoms before coronary artery bypass grafting are related to higher hospital readmission rates 6 months after the procedure. Nurses can play a pivotal role in determining which patients require evaluation, educating patients, and initiating effective treatment, which may prevent readmission related to depressive symptoms.

Current status of cardiac surgery in the abciximab-treated patient

BACKGROUND

Early surgical experience with abciximab and other glycoprotein (GP) IIb/IIIa receptor antagonists suggested a tendency toward excessive bleeding in patients treated with these agents. With increased use of GP IIb/IIIa inhibitors, cardiac surgeons have become aware of their hazards, as well as potential benefits, during and after cardiac surgery. Although published experience with the GP IIb/IIIa inhibitor abciximab is limited in scope, it suggests management guidelines for urgent coronary artery bypass grafting in abciximab-treated patients. As more urgent and elective surgical data are presented, a clearer picture of true bleeding risk will evolve.

METHODS

Two large retrospective studies examining reexploration for postoperative bleeding have identified risk factors, including advanced age, preoperative renal dysfunction, and operation/reoperation other than coronary artery bypass grafting. Other risk factors for transfusion requirement and increased morbidity and mortality are emergent operation, postoperative coagulopathy, and prolonged bypass time.

RESULTS

To minimize real and perceived bleeding effects, some authors have suggested delaying operation until platelet function has normalized, employing platelet transfusion in patients in whom delay is not possible, and exacting heparin management during cardiopulmonary bypass. Later reports have not noted increased bleeding when incorporating these modifications plus early platelet transfusion, if required. Further experience with abciximab removal and reversal may also ultimately reduce or eliminate excess transfusion requirements.

CONCLUSIONS

Surgeons should work closely with perfusionists and anesthesiologists on issues of heparinization in the abciximab-treated patient. The apparent paradox of preserved platelet numbers and depressed platelet function with abciximab use has led to speculation about a role for this agent and other shorter-acting GP IIb/IIIa inhibitors for "platelet anesthesia" during cardiopulmonary bypass. With careful surgical care, GP IIb/IIIa receptor antagonists can maintain and improve beneficial outcomes.

Abciximab and bleeding during coronary surgery: results from the EPILOG and EPISTENT trials. Improve Long-term Outcome with abciximab GP IIb/IIIa blockade. Evaluation of Platelet IIb/IIIa Inhibition in STENTing

BACKGROUND

Abciximab during percutaneous coronary revascularization reduces ischemic complications, but concern exists regarding increased bleeding risk should emergency coronary surgical procedures be required.

METHODS

Outcomes were assessed among 85 patients who required coronary artery bypass grafting operations after coronary intervention in two randomized placebo-controlled trials of abciximab. Comparisons were made between patients in the pooled placebo and abciximab groups.

RESULTS

The incidence of coronary surgical procedures was 2.17% and 1.28% among patients randomized to placebo and abciximab, respectively (p = 0.021). Platelet transfusions were administered to 32% and 52% of patients in the placebo and abciximab groups, respectively (p = 0.059). Rates of major blood loss were 79% and 88% in the placebo and abciximab groups, respectively (p = 0.27); transfusions of packed red blood cells or whole blood were administered in 74% and 80% of patients, respectively (p = 0.53). Surgical reexploration for bleeding was required in 3% and 12% of patients, respectively. Death and myocardial infarction tended to occur less frequently among patients who had received abciximab.

CONCLUSIONS

Urgent coronary artery bypass grafting operations can be performed without an incremental increase in major hemorrhagic risk among patients on abciximab therapy.

Intraoperative physiologic variables and outcome in cardiac surgery: Part I. In-hospital mortality

BACKGROUND

Risk stratification schemes have been developed to predict outcome of coronary artery bypass grafting (CABG) procedures, which are predominately based upon unalterable preoperative patient characteristics. The purpose of this study was to determine if minimum intraoperative hematocrit, maximum glucose concentration, mean arterial pressure on cardiopulmonary bypass, or duration of bypass influence risk-adjusted in-hospital mortality after CABG.

METHODS

Outcome data from 2,862 CABG patients were merged with intraoperative physiologic data. A preoperative mortality risk index was calculated for each patient. Variables found significant (p<0.05) by univariate logistic regression were tested in a multiple variable model to determine risk-adjusted association with mortality.

RESULTS

Overall mortality rate was 1.85%. The preoperative risk index was significantly associated with mortality (p = 0.0001). No significant association was present between mortality and intraoperative variables. Preexisting hypertension was an independent predictor of mortality after controlling for risk index and bypass duration.

CONCLUSIONS

Preexisting hypertension proved to be an independent predictor of mortality in our patient population. This study found no evidence to support the hypothesis that mean arterial pressure less than 50 mm Hg, lower hematocrit, or elevated glucose while on bypass increases in-hospital mortality.

Intraoperative physiologic variables and outcome in cardiac surgery: Part II. Neurologic outcome

BACKGROUND

The impact of alterable physiologic variables on neurologic outcome after coronary artery bypass grafting procedures is unknown. The purpose of this study was to determine whether minimum intraoperative hematocrit, maximum glucose concentration, or mean arterial pressure during cardiopulmonary bypass influences risk-adjusted neurologic outcome after coronary artery bypass grafting.

METHODS

Outcome data from 2,862 patients undergoing coronary artery bypass grafting were merged with intraoperative physiologic data. A preoperative stroke risk index was calculated for each patient. Variables found significant by univariate logistic regression were tested in a multivariable model to determine association with outcome.

RESULTS

The incidence of stroke or coma in the study population was 1.3%. After controlling for stroke risk and bypass time, only an index of low mean arterial pressure during bypass retained a significant inverse association with outcome (p = 0.0304).

CONCLUSIONS

This study found no evidence that glucose concentration or minimum hematocrit are associated with major adverse neurologic outcome. The association between lower pressure during bypass and decreased incidence of stroke or coma persisted in all risk groups. This points to mechanisms other than hypoperfusion as the primary cause of neurologic injury associated with cardiac surgery.

Outcomes of cardiac surgery in patients > or = 80 years: results from the National Cardiovascular Network

OBJECTIVES

The purpose of this study was to evaluate characteristics and outcomes of patients age > or =80 undergoing cardiac surgery.

BACKGROUND

Prior single-institution series have found high mortality rates in octogenarians after cardiac surgery. However, the major preoperative risk factors in this age group have not been identified. In addition, the additive risks in the elderly of valve replacement surgery at the time of bypass are unknown.

METHODS

We report in-hospital morbidity and mortality in 67,764 patients (4,743 octogenarians) undergoing cardiac surgery at 22 centers in the National Cardiovascular Network. We examine the predictors of in-hospital mortality in octogenarians compared with those predictors in younger patients.

RESULTS

Octogenarians undergoing cardiac surgery had fewer comorbid illnesses but higher disease severity and surgical urgency than younger patients. Octogenarians had significantly higher in-hospital mortality after cardiac surgery than younger patients: coronary artery bypass grafting (CABG) only (8.1% vs. 3.0%), CABG/aortic valve (10.1% vs. 7.9%), CABG/mitral valve (19.6% vs. 12.2%). In addition, they had twice the incidence of postoperative stroke and renal failure. The preoperative clinical factors predicting CABG mortality in the very elderly were quite similar to those for younger patients with age, emergency surgery and prior CABG being the powerful predictors of outcome in both age categories. Of note, elderly patients without significant comorbidity had in-hospital mortality rates of 4.2% after CABG, 7% after CABG with aortic valve replacement (CABG/AVR), and 18.2% after CABG with mitral valve replacement (CABG/MVR).

CONCLUSIONS

Risks for octogenarians undergoing cardiac surgery are less than previously reported, especially for CABG only or CABG/AVR. In selected octogenarians without significant comorbidity, mortality approaches that seen in younger patients.

Cys-93-betabeta-succinimidophenyl polyethylene glycol 2000 hemoglobin A. Intramolecular cross-bridging of hemoglobin outside the central cavity

Bis(maleidophenyl)-PEG2000 (Bis-Mal-PEG2000), a new bifunctional protein cross-linker targeted to sulfhydryl groups, introduces intra-tetrameric cross-links into oxy-HbA in nearly quantitative yields. Structural as well as crystallographic analyses of the cross-linked species, Bis-Mal-PEG2000 HbA, identified Cys-93(beta) as the site of intramolecular cross-linking. The cross-bridging had only a limited influence on the O(2) affinity and cooperativity of HbA in 50 mM BisTris acetate, pH 7.4. However, the Bohr effect was reduced by approximately 60%. Bis-Mal-PEG2000 HbA retained sensitivity to the presence of allosteric effectors 2, 3-diphosphoglycerate, IHP, and chloride, albeit to a lesser degree compared with HbA. Crystallographic analysis revealed the overall structure of deoxy-Bis-Mal-PEG2000 HbA to be similar to deoxy-HbA but for the loss of the salt bridge between Asp-94(beta) and His-146(beta). The large influence of the cross-bridging on the alkaline Bohr effect of HbA is consistent with the loss of this salt bridge. Unlike the "central cavity cross-bridges" described previously, the cross-link introduced by Bis-Mal-PEG2000 into HbA is an "outside the central cavity cross-bridge." In view of its oxy-conformational specificity and limited influence on O(2) affinity, this new cross-linking strategy holds promise for the stabilization of new designer low O(2) affinity Hbs generated by recombinant DNA technology for applications as Hb based therapeutics.

Endoscopic versus open saphenous vein harvest: the effect on postoperative outcomes

BACKGROUND

Endoscopic vein harvest (EVH) has been promoted as a possible solution to the wound complications, incisional pain, and prolonged convalesce associated with open vein harvesting (OVH). The purpose of this study was to objectively compare the two techniques.

METHODS

One hundred patients were prospectively randomized to EVH or OVH. Primary outcomes were wound complications, pain (Medical Outcomes Study Pain Survey), and general health (SF-12). Secondary outcomes were operative times and patient preferences. Patients were assessed at hospital discharge, 3, and 6 weeks postdischarge.

RESULTS

No significant differences were detected in the primary outcomes: leg infection (p = 0.75), incisional pain (p = 0.74), physical health (p = 0.84), mental health (p = 0.47), and postoperative length of stay (p = 0.74). However, patient preference for EVH was highly significant (p < 0.01).

CONCLUSIONS

EVH does not demonstrate significant differences compared with OVH. This, coupled with higher operating room costs, should limit its use until clinical benefit is shown. However, strong patient preference and demand for EVH overshadow equivocal clinical outcomes.

Comparison of direct aortic and femoral cannulation for port-access cardiac operations

BACKGROUND

Differences in outcome after direct aortic cannulation (AORT) in the chest versus standard femoral arterial cannulation (FEM) have not been defined for minimally invasive cardiac operations utilizing the port-access approach.

METHODS

A retrospective study was performed of 165 patients undergoing port-access cardiac mitral valve operation (n = 126) or coronary artery bypass grafting (n = 39). In 113 patients, FEM was used, while in 52 patients, AORT was accomplished through a port in the first intercostal space.

RESULTS

AORT eliminated endoaortic balloon clamp migration (0/36 [0%] vs. 17/95 [18%]), and groin wound or femoral arterial complications (0/52 [0%] vs. 11/113 [10%]) without changing procedure times (363+/-55 vs. 355+/-70 minutes). Complications attributable to AORT were injury to the right internal mammary artery and aortic cannulation site bleeding in 1 patient each.

CONCLUSIONS

Direct aortic cannulation is technically easy, allows use of an endoaortic clamp, and avoids aorto-iliac arterial disease, the groin incision, and possible femoral arterial injury associated with femoral arterial cannulation. Direct arterial cannulation should expand the pool of patients eligible for port-access operation, and may become the standard for port-access procedures.

Distinguishing serious and playful fighting by children with learning disabilities and nondisabled children

The ability to distinguish serious from playful fighting by two groups of children with learning disabilities (LD) (mean age = 9.3 and 11.8 years) and non-LD children (mean age = 10.1 years) was examined. Children with LD were generally able to make this distinction, with older children being more accurate. However, the performance of children with LD was not as high as that of non-LD children: they used a smaller range of criteria; some criteria were used significantly less; and they were much more likely not to give any reason for the judgements made. On the other hand, the order in frequency of those criteria cited was similar for both non-LD children and children with LD. Physical actions of the participants, and inference about actions and/or intent were the most frequently cited criteria. These findings indicate that although children with LD use fewer social cues, and are less accurate in making judgements about the nature of behavioural episodes, the acquisition of the meaning of particular cues may follow the same sequence as for non-LD children. Possible delays in the social cognitive development of children with LD, and their implications for the social adjustment of these children, are discussed.

Persistent left superior vena cava and partial anomalous pulmonary venous connection: incidental diagnosis by transesophageal echocardiography during coronary artery bypass surgery

Transesophageal echocardiography plays an important role in the intraoperative treatment of the heart surgery patient. Its utility in the description of both known and unexpected cardiac pathology is well established. We describe a patient with a previously undiagnosed partial anomalous pulmonary venous connection along with a persistent left superior vena cava scheduled for routine coronary artery bypass graft surgery (CABG).

Infant cardiopulmonary bypass: a procoagulant state

BACKGROUND

Procoagulant activity after cardiopulmonary bypass (CPB) in infants may predispose to thrombotic and bleeding complications. The induction of tissue factor and prothrombinase activity on endothelial cell membranes is a primary step in the activation of the extrinsic clotting cascade. The purpose of this study is to characterize the fibrinolytic and endothelial procoagulant state in infants undergoing congenital cardiac repairs with and without CPB.

METHODS

Fourteen infants (aged 1 to 12 weeks) underwent repair of congenital cardiac defects. Two patients had closed procedures (controls) and 12 had open cardiac procedures. Serum samples were taken before and after CPB, 1, 4, and 24 hours after CPB. Tissue plasminogen activator, plasminogen activator inhibitor-1, interleukin-1beta, interleukin-6, plasma tissue factor, and factor V levels were measured. Human umbilical vein endothelial cell cultures were incubated with serum taken from the above time points and assayed for induction of tissue factor and prothrombinase activity.

RESULTS

Control patients had no change from preoperative values in any of the parameters examined. In experimental patients, tissue plasminogen activator levels peaked at 1 hour after CPB and then decreased to normal by 24 hours. Plasminogen activator inhibitor-1 levels peaked at 4 hours after CPB and returned to baseline by 24 hours. The plasma of all patients had no intrinsic tissue factor activity. Induction of tissue factor activity on umbilical vein endothelial cells peaked immediately and again at 24 hours, whereas prothrombinase activity peaked early and stayed elevated. Serum factor V levels were significantly reduced after CPB, but returned to near baseline levels by 24 hours.

CONCLUSIONS

Cardiopulmonary bypass is associated with derangement of the coagulation and fibrinolytic systems in infants. The serum of these patients promotes the induction of endothelial procoagulant activity, suggesting that there may be a hypercoagulable state in the postbypass period.

The impact of parental separation/divorce on grandparent-grandchild relationships

Eighty-six members of the Grandparents' Federation in Britain returned questionnaires about changes in contact with their grandchildren following parental divorce; ten grandparents were also interviewed to obtain more contextual information and measures of health and coping strategies. Three questionnaire measures of the grandparent-grandchild relationship, proximity, contact frequency, and emotional involvement, were interrelated and a significant decrease was reported after parental divorce. There were no significant differences on these measures between grandparents all of whose grandchildren were affected by parental divorce, and grandparents for whom only some grandchildren were so affected; but the latter group did show a greater decline in emotional involvement and also had less recourse to legal action to sustain contact. With grandchildren affected by parental divorce, proximity to grandparents was not significantly less than for grandchildren not so affected, but contact and emotional involvement were significantly less. Many grandparents reported emotional and physical health problems related to the loss of contact. Results are discussed in terms of the extent to which grandparents are victims of the divorce situation, or agents involved in cross-generational family dysfunction; the victim model appears to get more support from our data. Recommendations are made for further research, as well as counseling to help move grandparents through the grief process and to a better quality of life.

Self-reports of short- and long-term effects of bullying on children who stammer

BACKGROUND

Victimisation at school may result in long-term social, emotional and psychological effects (Parker & Asher, 1987; Sharp, 1995), particularly for children with special educational needs (Whitney et al., 1994). Children who stammer may be at risk of being bullied due to their peer-relationship and verbal difficulties.

AIM

This study aimed to explore the nature, frequency and causes of bullying amongst children who stammer as well as the short- and long-term effects of their victimisation.

SAMPLE

The sample consisted of 276 respondents from the British Stammering Association, a national association for dysfluent people.

METHOD

A retrospective analysis of school experiences related to bullying, and its effects, was conducted through both semi-structured interviews and postal questionnaires.

RESULTS

A majority of respondents had experienced bullying at school, and the likelihood of being bullied was related to the reported difficulties in friendship-making. Nearly one-half of teachers and families were reported as not being aware of this bullying. A majority reported immediate negative personal effects of this bullying, and 46% reported some long-term effects.

CONCLUSION

Logistic regression analyses suggested that the severity of bullying, together with other factors such as difficulty with friendships, predicted these effects.

COMMENT

In response to the high incidence of bullying experienced by children who stammer, a pack has been developed which aims to create a more empathetic school climate where differences are tolerated rather than assaulted.

Optimizing liquid ventilation as a lung protection strategy for neonatal cardiopulmonary bypass: full functional residual capacity dosing is more effective than half functional residual capacity dosing

OBJECTIVE

To evaluate and compare the protective effects of two different perflubron doses on hemodynamics and lung function in a neonatal animal model of cardiopulmonary bypass-induced lung injury.

DESIGN

Prospective, randomized, controlled study.

SETTING

Animal laboratory of the Department of Surgery, Duke University Medical Center.

SUBJECTS

Twenty-one neonatal swine.

INTERVENTIONS

One-wk-old swine (2.2-3.2 kg) were randomized to receive cardiopulmonary bypass with full functional residual capacity perflubron (n = 7), cardiopulmonary bypass with half functional residual capacity perflubron (n = 7), or cardiopulmonary bypass alone (n = 7). This last group served as control animals, receiving cardiopulmonary bypass with conventional ventilation. Liquid lung ventilation animals received perflubron via the endotracheal tube at either full functional residual capacity (16-20 mL/kg) or half functional residual capacity (10 mL/kg) before the initiation of cardiopulmonary bypass. Each animal was placed on nonpulsatile cardiopulmonary bypass and cooled to a nasopharyngeal temperature of 18 degrees C (64.4 degrees F). Low-flow cardiopulmonary bypass (35 mL/kg/min) was instituted for 90 mins. The blood flow rate was then returned to 100 mL/kg/min. The animals were warmed to 36 degrees C (96.8 degrees F) and separated from cardiopulmonary bypass. Data were obtained at 30, 60, and 90 mins after separation from cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Cardiopulmonary bypass without liquid lung ventilation resulted in a significant decrease in cardiac output and oxygen delivery and a significant increase in pulmonary vascular resistance in the post-bypass period. Full functional residual capacity liquid lung ventilation administered before bypass resulted in no change in cardiac output and oxygen delivery after bypass. Full functional residual capacity liquid lung ventilation resulted in lower pulmonary vascular resistance after bypass compared with both control and half functional residual capacity liquid lung ventilation animals.

CONCLUSIONS

These data suggest that liquid lung ventilation dosing at full functional residual capacity before bypass is more effective than half functional residual capacity in minimizing the lung injury associated with neonatal cardiopulmonary bypass. Full functional residual capacity dosing may optimize alveolar distention and lung volume, as well as improve oxygen delivery compared with half functional residual capacity dosing.

Epsilon-aminocaproic acid administration and stroke following coronary artery bypass graft surgery

BACKGROUND

Epsilon-aminocaproic acid is routinely used to reduce bleeding during cardiac surgery. Anecdotal reports of thrombotic complications have led to speculation regarding this drug's safety. We investigated the association between epsilon-aminocaproic acid administration and postoperative stroke.

METHODS

Six thousand two hundred ninety-eight patients undergoing isolated coronary artery bypass graft surgery between 1989 and 1995 were studied. Data was obtained from the Duke Cardiovascular Database as well as from an automated intraoperative anesthesia record keeper. Patients identified as having postoperative stroke were reviewed and confirmed by a board certified neurologist blinded to epsilon-aminocaproic acid administration.

RESULTS

Postoperative stroke occurred in 97 patients (1.5%). Three thousand one hundred thirty-five (49.8%) patients received epsilon-aminocaproic acid. Increased age was associated with a higher incidence of postoperative stroke (p = 0.0001). In contrast, there was no significant difference (p = 0.7370) in the incidence of stroke between use of epsilon-aminocaproic acid (1.3%) and nonuse (1.7%). Multivariable logistic regression found no significant effect of epsilon-aminocaproic acid use on stroke after accounting for age, date of surgery, and history of diabetes.

CONCLUSIONS

This series suggests that epsilon-aminocaproic acid administration does not increase the risk of postoperative stroke.

Comparison of omental and pectoralis flaps for poststernotomy mediastinitis

BACKGROUND

Pectoralis flaps are frequently used to treat poststernotomy mediastinitis. We compared the outcomes of omental transfer, an alternative treatment for mediastinitis, with those of pectoralis flaps.

METHODS

Patients treated for poststernotomy mediastinitis with isolated omental flaps (n = 21) were compared with a group of consecutive patients treated with pectoralis flaps (n = 38). Baseline characteristics were equivalent for the two groups, and both early and late outcomes were compared.

RESULTS

Length of procedure and length of postoperative hospitalization were reduced significantly and there were significantly fewer early complications in the group treated with omental flaps. Furthermore, there were no early or late flap failures or abscesses in the omental flap group.

CONCLUSIONS

This study found that omental flaps had improved early outcomes and are a more effective therapy relative to pectoralis flaps for poststernotomy mediastinitis. Technical considerations for omental transfer that could optimize results are given.

Determinants of 15-year outcome with 1,119 standard Carpentier-Edwards porcine valves

BACKGROUND

The determinants of long-term outcome 15 years or more after porcine valve replacement are poorly documented.

METHODS

A retrospective review was performed of patients undergoing valve replacement with standard Carpentier-Edwards aortic (n = 531), mitral (n = 492), and tricuspid (n = 96) valves.

RESULTS

Patient survival was 26%+/-3%, 23%+/-2%, and 31%+/-8% 15 years after aortic, mitral, and tricuspid valve replacements, respectively. Independent determinants of impaired long-term survival for aortic or mitral valve replacement were multiple valve replacement, older age, renal disease, lung disease, or coronary disease. Actual (versus actuarial) freedom from reoperation at 15 years was 86%+/-2%, 76%+/-2%, and 95%+/-2% after aortic, mitral, and tricuspid valve replacement, respectively. Risk factors for reoperation were young age for aortic or mitral valve replacement, previous operation for aortic valve replacement, and large valve size for mitral valve replacement. Freedom from thromboembolism was 77%+/-4%, 62%+/-9%, and 80%+/-5%; from hemorrhage, 95%+/-5%, 87%+/-4%, and 82%+/-6%; and from endocarditis, 94%+/-1%, 96%+/-1%, and 89%+/-5% 15 years after aortic, mitral, and tricuspid valve replacement, respectively. Risk factors for thromboembolism or hemorrhage were multiple valve replacement and age.

CONCLUSIONS

The standard Carpentier-Edwards bioprosthesis continues to provide relatively low complication rates at 15 years, especially in the aortic and tricuspid positions, and especially in patients older than 60 years or with significant comorbdity.

Shedding of L-selectin and PECAM-1 and upregulation of Mac-1 and ICAM-1 on neutrophils in RSV bronchiolitis

Bronchiolitis is characterized histologically by epithelial necrosis and peribronchial infiltration of leukocytes, with a high percentage of neutrophils in the airways. We investigated the expression of adhesion molecules (CD11a, CD11b, CD18, CD31, CD54, and CD62L) on neutrophils from nasopharyngeal aspirates (NPAs) and peripheral blood (PB) of infants with respiratory syncytial virus (RSV)-induced bronchiolitis. The expression of CD31 and CD62L on neutrophils from NPAs is decreased and the expression of CD11b, CD18, and CD54 on neutrophils from NPAs is increased compared with cells from PB of RSV-infected infants. The expression of CD18 and CD54 on neutrophils from PB of RSV-infected infants is also increased compared with cells from PB of control infants. Shedding of CD31 and CD62L on neutrophils in RSV infection may contribute to the neutrophil emigration from blood to airways; the upregulation of Mac-1 (CD11b/CD18) and CD54 on neutrophils may help explain the high percentage of neutrophils in the airways of RSV bronchiolitis; and the upregulation of Mac-1 may be involved in the increased neutrophil-airway epithelial adhesion in RSV infection.

The apoptosis of neutrophils is accelerated in respiratory syncytial virus (RSV)-induced bronchiolitis

Neutrophils are the predominant inflammatory cell in the lung tissues and airways in RSV infection, and can augment the epithelial cell damage induced by RSV. Neutrophil apoptosis has been suggested to be a mechanism to reduce the potential for tissue injury. The apoptosis of neutrophils from nasopharyngeal aspirates (NPA) (n = 19) and peripheral blood (PB) of infants with RSV bronchiolitis (n = 11) and PB from healthy controls (n = 9) was investigated. Monoclonal antibody against CD95 (Fas) and a binding protein Annexin V were used to determine the apoptosis of neutrophils. The expression of CD11b and CD18 on neutrophils was also detected with flow cytometry. The mean fluorescence intensity (MFI) of CD95 on neutrophils from RSV+ NPA was increased compared with cells from control PB (73.6 +/- 7.6 versus 31.5 +/- 4.3); the MFI of Annexin V, CD11b and CD18 on neutrophils from RSV+ NPA was up-regulated compared with cells from both control PB (105.3 +/- 18.1 versus 11.8 +/- 1.5; 1683 +/- 153.3 versus 841.1 +/- 72.3; 517 +/- 50.5 versus 147 +/- 8.7, respectively) and RSV+ PB (105.3 +/- 18.1 versus 35.8 +/- 4.1; 1683 +/- 153.3 versus 818 +/- 141.2; 517 +/- 50.5 versus 260 +/- 25.8, respectively). Furthermore, the percentage of neutrophils expressing Annexin V and the MFI of CD18 on neutrophils from RSV+ PB were increased compared with neutrophils from control PB. In addition, both CD11b (MFI) and CD18 (MFI) correlated with Annexin V (MFI) on neutrophils. We conclude that neutrophil apoptosis in RSV bronchiolitis is accelerated; and CD11b/CD18 may play an important role in RSV infection by influencing neutrophil apoptosis.

Mitral valve operation via Port Access versus median sternotomy

OBJECTIVE

The advantages and disadvantages of minimally invasive Port Access mitral valve operation have not been defined relative to standard median sternotomy. A study was therefore designed to delineate differences in outcome from mitral operation via Port Access versus sternotomy in comparable patients.

METHODS

The records of 41 consecutive patients undergoing isolated mitral valve replacement (n = 14) or repair (n = 27) were examined. All operations were performed using cardioplegic arrest through either median sternotomy (n = 20) or a small right anterolateral thoracotomy using an endoaortic clamp and catheter system (Heartport, Redwood City, CA) to arrest and decompress the heart (Port Access, n = 21).

RESULTS

Both groups were well matched for age, mitral pathology, ejection fraction, and comorbidity. except that Port Access patients were less likely to be female. Three patients had undergone previous cardiac operations. Surgical procedure time was longer for Port Access patients (384+/-80 vs. 263+/-41 min, P < 0.05). Port Access provided significantly smaller incision length (8+/-2 vs. 26+/-2 cm, P < 0.01) and similar or shorter hospital stay (6+/-4 vs. 7+/-3 days). Port Access provided excellent visualization of the mitral valve and subvalvular apparatus, generally better than sternotomy, to allow complex mitral valve repairs. The greatest advantage of Port Access mitral operation was that Port Access patients returned to normal activity more rapidly (4+/-2 vs. 9+/-1 weeks, P = 0.01) than did patients undergoing standard median sternotomy.

CONCLUSIONS

By avoiding a sternotomy, Port Access mitral valve operation provided a smaller incision and a dramatically more rapid return to normal activity than did median sternotomy. Port Access cardioplegic arrest with the Heartport system allowed visualization of the mitral valve superior to median sternotomy and has become the standard approach at this institution.

Childhood stress, behavioural symptoms and mother-daughter pubertal development

Belsky, Steinberg and Draper (Child Development 1991, 62, 647-670) predicted that early childhood stress or conflict in the family environment would be associated with childhood behavioural symptoms, early puberty and early, less discriminate sexual behaviour. Their theory was tested in a retrospective self-report survey in 28 daughters (aged 12 to 15) and 21 mothers. In daughters, earlier menarche correlated with more family stress in a late childhood (age 7 to 11); more conflict with mother in early childhood (birth to age 6); more rejection from and less closeness to mother throughout childhood (birth to age 11); more anxiousness and internalizing symptoms (anxiousness/depression) in late childhood (age 7 to 11); earlier age at dating boys; and more boyfriends. An alternative interpretation is considered based on genetic transmission of maternal characteristics.

Physical activity play: the nature and function of a neglected aspect of playing

In this review, we consider the nature and possible developmental functions of physical activity play, defined as a playful context combined with a dimension of physical vigor. We distinguish 3 kinds of physical activity play, with consecutive age peaks: rhythmic stereotypies peaking in infancy, exercise play peaking during the preschool years, and rough-and-tumble play peaking in middle childhood. Gender differences (greater prevalence in males) characterize the latter 2 forms. Function is considered in terms of beneficial immediate and deferred consequences in physical, cognitive, and social domains. Whereas most theories assume that children's play has deferred benefits, we suggest that forms of physical activity play serve primarily immediate developmental functions. Rhythmic stereotypies in infancy are hypothesized to improve control of specific motor patterns. Exercise play is hypothesized to function primarily for strength and endurance training; less clear evidence exists for possible benefits for fat reduction and thermoregulation. In addition, there may be cognitive benefits of exercise play that we hypothesize to be largely incidental to its playful or physical nature. Rough-and-tumble play has a distinctive social component; we hypothesize that it serves primarily dominance functions; evidence for benefits to fighting skills or to emotional coding are more equivocal. Further research is indicated, given the potentially important implications for children's education, health, and development.

Increasing tidal volumes and pulmonary overdistention adversely affect pulmonary vascular mechanics and cardiac output in a pediatric swine model

OBJECTIVES

In a pediatric swine model, the effects of increasing tidal volumes and the subsequent development of pulmonary overdistention on cardiopulmonary interactions were studied. The objective was to test the hypothesis that increasing tidal volumes adversely affect pulmonary vascular mechanics and cardiac output. An additional goal was to determine whether the effects of pulmonary overdistention are dependent on delivered tidal volume and/or positive end-expiratory pressure (PEEP, end-expiratory lung volume).

DESIGN

Prospective, randomized, controlled laboratory trial.

SETTING

University research laboratory.

SUBJECTS

Eleven 4- to 6-wk-old swine, weighing 8 to 12 kg.

INTERVENTIONS

Piglets with normal lungs were anesthetized, intubated, and paralyzed. After median sternotomy, pressure transducers were placed in the right ventricle, pulmonary artery, and left atrium. An ultrasonic flow probe was placed around the pulmonary artery.

MEASUREMENTS AND MAIN RESULTS

The swine were ventilated and data were collected with delivered tidal volumes of 10, 15, 20, and 25 mL/kg and PEEP settings of 5 and 10 cm H2O in a random order. Pulmonary overdistention was defined as a decrease in dynamic compliance of > or =20% when compared with a compliance measured at a baseline tidal volume of 10 mL/kg. At this baseline tidal volume, airway pressure-volume curves did not demonstrate pulmonary overdistention. Tidal volumes and airway pressures were measured by a pneumotachometer and the Pediatric Pulmonary Function Workstation. Inspiratory time (0.75 sec), FIO2 (0.3), and minute ventilation were held constant. We evaluated the pulmonary vascular and cardiac effects of the various tidal volume and PEEP settings by measuring pulmonary vascular resistance, pulmonary characteristic impedance, and cardiac output. When compared with a tidal volume of 10 mL/kg, a tidal volume of 20 mL/kg resulted in a significant decrease in dynamic compliance from 10.5 +/- 0.9 to 8.4 +/- 0.6 mL/cm H2O (p = .02) at a constant PEEP of 5 cm H2O. The decrease in dynamic compliance of 20% indicated the presence of pulmonary overdistention by definition. As the tidal volume was increased from 10 to 20 mL/kg, pulmonary vascular resistance (1351 +/- 94 vs. 2266 +/- 233 dyne x sec/cm5; p = .004) and characteristic impedance (167 +/- 12 vs. 219 +/- 22 dyne x sec/cm5; p = .02) significantly increased, while cardiac output significantly decreased (951 +/- 61 vs. 708 +/- 48 mL/min; p = .001). Each of these effects of pulmonary overdistention were further magnified when the tidal volume was increased to 25 mL/kg. The tidal volume-induced alterations in pulmonary vascular mechanics, characteristic impedance, and cardiac output occurred to a greater degree when the PEEP was increased to 10 cm H2O. Pulmonary vascular resistance and characteristic impedance were significantly increased and cardiac output significantly decreased for all tidal volumes studied at a PEEP of 10 cm H2O as compared with 5 cm H2O.

CONCLUSIONS

Increasing tidal volumes, increasing PEEP levels, and the development of pulmonary overdistention had detrimental effects on the cardiovascular system by increasing pulmonary vascular resistance and characteristic impedance while significantly decreasing cardiac output. Delivered tidal volumes of >15 mL/kg should be utilized cautiously. Careful monitoring of respiratory mechanics and cardiac function, especially in neonatal and pediatric patients, is warranted.

Liquid ventilation improves pulmonary function and cardiac output in a neonatal swine model of cardiopulmonary bypass

OBJECTIVE

Neonatal and infant cardiopulmonary bypass results in multiorgan system dysfunction. Organ protective strategies have traditionally been directed at the myocardium and brain while neglecting the sometimes severe injury to the lungs. We hypothesized that liquid ventilation would improve pulmonary function and cardiac output in neonates after cardiopulmonary bypass.

METHODS

Twenty neonatal swine were randomized to receive cardiopulmonary bypass with or without liquid ventilation. In the liquid-ventilated group, a single dose of perflubron was administered before bypass. The control group was conventionally ventilated. Each animal was placed on nonpulsatile, hypothermic bypass. Low-flow cardiopulmonary bypass was performed for 60 minutes. The flow rate was returned to 125 ml/kg per minute, and after warming to 37 degrees C, the animals were removed from bypass. Hemodynamic and ventilatory data were obtained after bypass to assess the effects of liquid ventilation.

RESULTS

Without liquid ventilation, cardiopulmonary bypass resulted in a significant decrease in cardiac output, oxygen delivery, and static pulmonary compliance compared with prebypass values. Input pulmonary resistance and characteristic impedance increased in these control animals. At 30, 60, and 90 minutes after bypass, the animals receiving liquid ventilation showed significantly increased cardiac output and static compliance and significantly decreased input pulmonary resistance and characteristic impedance compared with control animals not receiving liquid ventilation.

CONCLUSIONS

Liquid ventilation improved pulmonary function after neonatal cardiopulmonary bypass while increasing cardiac output. The morbidity associated with cardiopulmonary bypass may be significantly reduced if the adverse pulmonary sequelae of bypass can be diminished. Liquid ventilation may become an important technique to protect the lungs from the deleterious effects of cardiopulmonary bypass.

Cost-benefit and efficacy of aprotinin compared with epsilon-aminocaproic acid in patients having repeated cardiac operations: a randomized, blinded clinical trial

BACKGROUND

Aprotinin and epsilon-aminocaproic acid are routinely used to reduce bleeding during cardiac surgery. The marked difference in average wholesale cost between these two drug therapies (aprotinin, $1,080 vs. epsilon-aminocaproic acid, $11) has generated significant controversy regarding their relative efficacies and costs.

METHODS

In a multicenter, randomized, prospective, blinded trial, patients having repeated cardiac surgery received either a high-dose regimen of aprotinin (total dose, 6 x 10(6) kallikrein inactivator units) or epsilon-aminocaproic acid (total dose, 270 mg/kg).

RESULTS

Two hundred four patients were studied. Overall (data are median [25th-75th percentiles]), aprotinin-treated patients had less postoperative thoracic drainage (511 ml [383-805 ml] vs. 655 ml [464-1,045 ml]; P = 0.016) and received fewer platelet transfusions (0 [range, 0-1] vs. 1 [range, 0-2]; P = 0.036). The surgical field was more likely to be considered free of bleeding in aprotinin-treated patients (44% vs. 26%; P = 0.012). No differences, however, were seen in allogeneic erythrocyte transfusions or in the time required for chest closure. Overall, direct and indirect bleeding-related costs were greater in aprotinin- than in epsilon-aminocaproic acid-treated patients ($1,813 [$1,476-2,605] vs. $1,088 [range, $511-2,057]; P = 0.0001). This difference in cost per case varied in magnitude among sites but not in direction.

CONCLUSIONS

Aprotinin was more effective than epsilon-aminocaproic acid at decreasing bleeding and platelet transfusions. Epsilon-aminocaproic acid, however, was the more cost-effective therapy over a broad range of estimates for bleeding-related costs in patients undergoing repeated cardiac surgery. A cost-benefit analysis using the lower cost of half-dose aprotinin ($540) still resulted in a significant cost advantage using epsilon-aminocaproic therapy (P = 0.022).