Separating the components of an abdominal wall fellowship

Complex abdominal wall reconstruction is an emerging subspecialty yet, despite the abundance of abdominal wall hernias requiring treatment and the increasing complexity of this type of surgery, there are few opportunities for surgeons to gain subspecialist training in this field. In this paper we discuss the need for focused training in complex abdominal wall reconstruction, outline some of the problems that may be hindering the availability of such opportunities and propose potential solutions to these issues.

Anti-inflammatory therapy enables robot-actuated regeneration of aged muscle

Robot-actuated mechanical loading (ML)-based therapies ("mechanotherapies") can promote regeneration after severe skeletal muscle injury, but the effectiveness of such approaches during aging is unknown and may be influenced by age-associated decline in the healing capacity of skeletal muscle. To address this knowledge gap, this work used a noninvasive, load-controlled robotic device to impose highly defined tissue stresses to evaluate the age dependence of ML on muscle repair after injury. The response of injured muscle to robot-actuated cyclic compressive loading was found to be age sensitive, revealing not only a lack of reparative benefit of ML on injured aged muscles but also exacerbation of tissue inflammation. ML alone also disrupted the normal regenerative processes of aged muscle stem cells. However, these negative effects could be reversed by introducing anti-inflammatory therapy alongside ML application, leading to enhanced skeletal muscle regeneration even in aged mice.

Investigation of the gut microbiome, bile acid composition and host immunoinflammatory response in a model of azoxymethane-induced colon cancer at discrete timepoints

BACKGROUND

Distinct sets of microbes contribute to colorectal cancer (CRC) initiation and progression. Some occur due to the evolving intestinal environment but may not contribute to disease. In contrast, others may play an important role at particular times during the tumorigenic process. Here, we describe changes in the microbiota and host over the course of azoxymethane (AOM)-induced tumorigenesis.

METHODS

Mice were administered AOM or PBS and were euthanised 8, 12, 24 and 48 weeks later. Samples were analysed using 16S rRNA gene sequencing, UPLC-MS and qRT-PCR.

RESULTS

The microbiota and bile acid profile showed distinct changes at each timepoint. The inflammatory response became apparent at weeks 12 and 24. Moreover, significant correlations between individual taxa, cytokines and bile acids were detected. One co-abundance group (CAG) differed significantly between PBS- and AOM-treated mice at week 24. Correlation analysis also revealed significant associations between CAGs, bile acids and the bile acid transporter, ASBT. Aberrant crypt foci and adenomas were first detectable at weeks 24 and 48, respectively.

CONCLUSION

The observed changes precede host hyperplastic transformation and may represent early therapeutic targets for the prevention or management of CRC at specific timepoints in the tumorigenic process.

Comprehensive multi-cohort transcriptional meta-analysis of muscle diseases identifies a signature of disease severity

Muscle diseases share common pathological features suggesting common underlying mechanisms. We hypothesized there is a common set of genes dysregulated across muscle diseases compared to healthy muscle and that these genes correlate with severity of muscle disease. We performed meta-analysis of transcriptional profiles of muscle biopsies from human muscle diseases and healthy controls. Studies obtained from public microarray repositories fulfilling quality criteria were divided into six categories: (i) immobility, (ii) inflammatory myopathies, (iii) intensive care unit (ICU) acquired weakness (ICUAW), (iv) congenital muscle diseases, (v) chronic systemic diseases, (vi) motor neuron disease. Patient cohorts were separated in discovery and validation cohorts retaining roughly equal proportions of samples for the disease categories. To remove bias towards a specific muscle disease category we repeated the meta-analysis five times by removing data sets corresponding to one muscle disease class at a time in a "leave-one-disease-out" analysis. We used 636 muscle tissue samples from 30 independent cohorts to identify a 52 gene signature (36 up-regulated and 16 down-regulated genes). We validated the discriminatory power of this signature in 657 muscle biopsies from 12 additional patient cohorts encompassing five categories of muscle diseases with an area under the receiver operating characteristic curve of 0.91, 83% sensitivity, and 85.3% specificity. The expression score of the gene signature inversely correlated with quadriceps muscle mass (r = -0.50, p-value = 0.011) in ICUAW and shoulder abduction strength (r = -0.77, p-value = 0.014) in amyotrophic lateral sclerosis (ALS). The signature also positively correlated with histologic assessment of muscle atrophy in ALS (r = 0.88, p-value = 1.62 × 10^-3) and fibrosis in muscular dystrophy (Jonckheere trend test p-value = 4.45 × 10^-9). Our results identify a conserved transcriptional signature associated with clinical and histologic muscle disease severity. Several genes in this conserved signature have not been previously associated with muscle disease severity.

Physical activity recommendations pre and post abdominal wall reconstruction: a scoping review of the evidence

PURPOSE

There are no universally agreed guidelines regarding which types of physical activity are safe and/or recommended in the perioperative period for patients undergoing ventral hernia repair or abdominal wall reconstruction (AWR). This study is intended to identify and summarise the literature on this topic.

METHODS

Database searches of PubMed, CINAHL, Allied & Complementary medicine database, PEDro and Web of Science were performed followed by a snowballing search using two papers identified by the database search and four hand-selected papers of the authors' choosing. Inclusion-cohort studies, randomized controlled trials, prospective or retrospective. Studies concerning complex incisional hernia repairs and AWRs including a "prehabilitation" and/or "rehabilitation" program targeting the abdominal wall muscles in which the interventions were of a physical exercise nature. RoB2 and Robins-I were used to assess risk of bias. Prospero CRD42021236745. No external funding. Data from the included studies were extracted using a table based on the Cochrane Consumers and Communication Review Group's data extraction template.

RESULTS

The database search yielded 5423 records. After screening two titles were selected for inclusion in our study. The snowballing search identified 49 records. After screening one title was selected for inclusion in our study. Three total papers were included-two randomised studies and one cohort study (combined 423 patients). All three studies subjected their patients to varying types of physical activity preoperatively, one study also prescribed these activities postoperatively. The outcomes differed between the studies therefore meta-analysis was impossible-two studies measured hernia recurrence, one measured peak torque. All three studies showed improved outcomes in their study groups compared to controls however significant methodological flaws and confounding factors existed in all three studies. No adverse events were reported.

CONCLUSIONS

The literature supporting the advice given to patients regarding recommended physical activity levels in the perioperative period for AWR patients is sparse. Further research is urgently required on this subject.

Reading a preoperative CT scan to guide complex abdominal wall reconstructive surgery

Computed tomography (CT) scanning is the imaging modality of choice when planning the overall management and operative approach to complex abdominal wall hernias. Despite its availability and well-recognised benefits there are no guidelines or recommendations regarding how best to read or report such scans for this application. In this paper we aim to outline an approach to interpreting preoperative CT scans in abdominal wall reconstruction (AWR). This approach breaks up the interpretive process into 4 steps-concentrating on the hernia or hernias, any complicating features of the hernia(s), the surrounding soft tissues and the abdominopelvic cavity as a whole-and was developed as a distillation of the authors' collective experience. We describe the key features that should be looked for at each of the four steps and the rationale for their inclusion.

Individualization of exosuit assistance based on measured muscle dynamics during versatile walking

Variability in human walking depends on individual physiology, environment, and walking task. Consequently, in the field of wearable robotics, there is a clear need for customizing assistance to the user and task. Here, we developed a muscle-based assistance (MBA) strategy wherein exosuit assistance was derived from direct measurements of individuals’ muscle dynamics during specific tasks. We recorded individuals’ soleus muscle dynamics using ultrasonographic imaging during multiple walking speeds and inclines. From these prerecorded images, we estimated the force produced by the soleus through inefficient concentric contraction and designed the exosuit assistance profile to be proportional to that estimated force. We evaluated this approach with a bilateral ankle exosuit at each measured walking task. Compared with not wearing a device, the MBA ankle exosuit significantly reduced metabolic demand by an average of 15.9, 9.7, and 8.9% for level walking at 1.25, 1.5, and 1.75 meters second−1, respectively, and 7.8% at 1.25 meters second−1 at 5.71° incline while applying lower assistance levels than in existing literature. In an additional study (n = 2), we showed for multiple walking tasks that the MBA profile outperforms other bioinspired strategies and the average profile from a previous optimization study. Last, we show the feasibility of online assistance generation in a mobile version for overground outdoor walking. This muscle-based approach enables relatively rapid (~10 seconds) generation of individualized low-force assistance profiles that provide metabolic benefit. This approach may help support the adoption of wearable robotics in real-world, dynamic locomotor tasks by enabling comfortable, tailored, and adaptive assistance.

The Role of Indocyanine Green Fluorescence Angiography in Complex Abdominal Wall Reconstruction: A Scoping Review of the Literature

BACKGROUND

Indocyanine green fluorescence angiography (ICGFA) is a technique for assessing vascularity and perfusion which has multiple proven applications across a variety of surgical procedures. Studies have been performed assessing its potential role in evaluating skin flap viability in complex abdominal wall reconstruction (CAWR) in order to avoid postoperative surgical site occurrences (SSO).

OBJECTIVES

This scoping review was intended to summarise the literature concerning ICGFA in CAWR in order to facilitate future evidence-based guidelines for its use.

ELIGIBILITY CRITERIA

Inclusion - cohort studies, randomised controlled trials, case series, case reports and ventral midline hernias only. Exclusion - patients aged under 18 years and non-human test subjects.

SOURCES OF EVIDENCE

PubMed, MEDLINE®, Cochrane, Embase and OpenGrey RESULTS: A total of 3416 unique titles were yielded from our search of which 9 met our inclusion criteria: 3 case reports, 1 retrospective case series, 1 prospective case series, 3 non-blinded, non-randomised retrospective case-controlled studies and 1 prospective, double-blinded randomised controlled study. The included studies varied considerably in size and method however the consensus appeared to support ICGFA as being a safe and feasible means of assessing tissue flap vascularity in CAWR. The studies returned contrasting results regarding the impact of ICGFA in predicting and avoiding SSOs however there were insufficient numbers of studies for a meta-analysis.

CONCLUSIONS

We identify three case reports and four lower quality studies suggesting a possible application for ICGFA in CAWR and two higher quality studies showing no overall benefit. Evidence-based guidelines on the role of ICGFA in CAWR will require the assessment of further studies.

Theatre ventilation

INTRODUCTION

Owing to the COVID-19 pandemic, there has been significant disruption to all surgical specialties. In the UK, units have cancelled elective surgery and a decrease in aerosol generating procedures (AGPs) was favoured. Centres around the world advocate the use of negative pressure environments for AGPs in reducing the spread of infectious airborne particles. We present an overview of operating theatre ventilation systems and the respective evidence with relation to surgical site infection (SSI) and airborne pathogen transmission in light of COVID-19.

METHODS

A literature search was conducted using the PubMed, Cochrane Library and MEDLINE databases. Search terms included "COVID-19", "theatre ventilation", "laminar", "turbulent" and "negative pressure".

FINDINGS

Evidence for laminar flow ventilation in reducing the rate of SSI in orthopaedic surgery is widely documented. There is little evidence to support its use in general surgery. Following previous viral outbreaks, some centres have introduced negative pressure ventilation in an attempt to decrease exposure of airborne pathogens to staff and surrounding areas. This has again been suggested during the COVID-19 pandemic. A limited number of studies show some positive results for the use of negative pressure ventilation systems and reduction in spread of pathogens; however, cost, accessibility and duration of conversion remain an unexplored issue. Overall, there is insufficient evidence to advocate large scale conversion at this time. Nevertheless, it may be useful for each centre to have its own negative pressure room available for AGPs and high risk patients.

Malnutrition, nutritional interventions and clinical outcomes of patients with acute small bowel obstruction: results from a national, multicentre, prospective audit

OBJECTIVE

The aim of this study was to assess the nutritional status of patients presenting with small bowel obstruction (SBO), along with associated nutritional interventions and clinical outcomes.

DESIGN

Prospective cohort study.

SETTING

131 UK hospitals with acute surgical services.

PARTICIPANTS

2069 adult patients with a diagnosis of SBO were included in this study. The mean age was 67.0 years and 54.7% were female.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was in-hospital mortality. Secondary outcomes recorded included: major complications (composite of in-hospital mortality, reoperation, unplanned intensive care admission and 30-day readmission), complications arising from surgery (anastomotic leak, wound dehiscence), infection (pneumonia, surgical site infection, intra-abdominal infection, urinary tract infection, venous catheter infection), cardiac complications, venous thromboembolism and delirium.

RESULTS

Postoperative adhesions were the most common cause of SBO (49.1%). Early surgery (<24 hours postadmission) took place in 30.0% of patients, 22.0% underwent delayed operation and 47.9% were managed non-operatively. Malnutrition as stratified by Nutritional Risk Index was common, with 35.7% at moderate risk and 5.7% at severe risk of malnutrition. Dietitian review occurred in just 36.4% and 55.9% of the moderate and severe risk groups. In the low risk group, 30.3% received nutritional intervention compared with 40.7% in moderate risk group and 62.7% in severe risk group. In comparison to the low risk group, patients who were at severe or moderate risk of malnutrition had 4.2 and 2.4 times higher unadjusted risk of in-hospital mortality, respectively. Propensity-matched analysis found no difference in outcomes based on use or timing of parenteral nutrition.

CONCLUSIONS

Malnutrition on admission is associated with worse outcomes in patients with SBO, and marked variation in management of malnutrition was observed. Future trials should focus on identifying effective and cost-effective nutritional interventions in SBO.

The Association of Coloproctology of Great Britain and Ireland consensus guidelines in surgery for inflammatory bowel disease

AIM

There is a requirement of an expansive and up to date review of surgical management of inflammatory bowel disease (IBD) that can dovetail with the medical guidelines produced by the British Society of Gastroenterology.

METHODS

Surgeons who are members of the ACPGBI with a recognised interest in IBD were invited to contribute various sections of the guidelines. They were directed to produce a procedure based document using literature searches that were systematic, comprehensible, transparent and reproducible. Levels of evidence were graded. An editorial board was convened to ensure consistency of style, presentation and quality. Each author was asked to provide a set of recommendations which were evidence based and unambiguous. These recommendations were submitted to the whole guideline group and scored. They were then refined and submitted to a second vote. Only those that achieved >80% consensus at level 5 (strongly agree) or level 4 (agree) after 2 votes were included in the guidelines.

RESULTS

All aspects of surgical care for IBD have been included along with 157 recommendations for management.

CONCLUSION

These guidelines provide an up to date and evidence based summary of the current surgical knowledge in the management of IBD and will serve as a useful practical text for clinicians performing this type of surgery.

Post-operative C-reactive protein profile following abdominal wall reconstruction with transversus abdominis posterior components separation

INTRODUCTION

Abdominal wall reconstruction using posterior component separation with transversus abdominis release (AWTAR) produces a unique post-operative CRP profile, when compared to routine elective colorectal operations. Therefore, we aim to establish the normal post-operative C-reactive protein (poCRP) profile following AWRTAR and reduce the unnecessary invasive interventions in patients already at greater risk of septic complications.

METHODS

A retrospective analysis of daily poCRP levels was performed both for patients who underwent uncomplicated AWRTAR (n=12), and a comparator group of uncomplicated open right hemicolectomies (RH) matched for age and sex (n=24). All operations in both groups were performed by a single surgeon from 2013 to 2015.

RESULTS

The median (IQR) age was 62 (16) and 67 (16) years respectively, with a higher proportion of males to females in both groups (10:2 vs. 17:7). The poCRP profile follows an initial steep rise, peaking at day 2 followed by a gradual washout phase. The poCRP peak is significantly greater in the AWRTAR group compared to the RH group (274 [95%CI ±25] vs. 160 [95%CI±27]; p=0.0001), with a positive correlation between day 2 CRP levels and operative length (r=0.56).

CONCLUSIONS

We have demonstrated that uncomplicated AWRTAR provokes a significantly greater poCRP rise (>200) compared to that well described in the literature for uncomplicated open colectomy. As poCRP is an important marker of post-operative recovery with abnormally high levels associated with septic complications, these data should help clinicians interpret the post-operative clinical course after AWRTAR.

Assistance magnitude versus metabolic cost reductions for a tethered multiarticular soft exosuit

When defining requirements for any wearable robot for walking assistance, it is important to maximize the user's metabolic benefit resulting from the exosuit assistance while limiting the metabolic penalty of carrying the system's mass. Thus, the aim of this study was to isolate and characterize the relationship between assistance magnitude and the metabolic cost of walking while also examining changes to the wearer's underlying gait mechanics. The study was performed with a tethered multiarticular soft exosuit during normal walking, where assistance was directly applied at the ankle joint and indirectly at the hip due to a textile architecture. The exosuit controller was designed such that the delivered torque profile at the ankle joint approximated that of the biological torque during normal walking. Seven participants walked on a treadmill at 1.5 meters per second under one unpowered and four powered conditions, where the peak moment applied at the ankle joint was varied from about 10 to 38% of biological ankle moment (equivalent to an applied force of 18.7 to 75.0% of body weight). Results showed that, with increasing exosuit assistance, net metabolic rate continually decreased within the tested range. When maximum assistance was applied, the metabolic rate of walking was reduced by 22.83 ± 3.17% relative to the powered-off condition (mean ± SEM).

Initial UK experience with transversus abdominis muscle release for posterior components separation in abdominal wall reconstruction of large or complex ventral hernias: a combined approach by general and plastic surgeons

Introduction Large, complicated ventral hernias are an increasingly common problem. The transversus abdominis muscle release (TAMR) is a recently described modification of posterior components separation for repair of such hernias. We describe our initial experience with TAMR and sublay mesh to facilitate abdominal wall reconstruction. Methods The study is a retrospective review of patients undergoing TAMR performed synchronously by gastrointestinal and plastic surgeons. Results Twelve consecutive patients had their ventral hernias repaired using the TAMR technique from June 2013 to June 2014. Median body mass index was 30.8kg/m² (range 19.0-34.4kg/m²). Four had a previous ventral hernia repair. Three had previous laparostomies. Four had previous stomas and three had stomas created at the time of the abdominal wall reconstruction. Average transverse distance between the recti was 13cm (3-20cm). Median operative time was 383 minutes (150-550 minutes) and mesh size was 950cm² (532-2400cm²). Primary midline fascial closure was possible in all cases, with no bridging. Median length of hospital stay was 7.5 days (4-17 days). Three developed minor abdominal wall wound complications. At median review of 24 months (18-37 months), there have been no significant wound problems, mesh infections or explants, and none has developed recurrence of their midline ventral hernia. Visual analogue scales revealed high patient satisfaction levels overall and with their final aesthetic appearance. Conclusions We believe that TAMR offers significant advantages over other forms of components separation in this patient group. The technique can be adopted successfully in UK practice and combined gastrointestinal and plastic surgeon operating yields good results.

Exacerbation risk in severe asthma is stratified by inflammatory phenotype using longitudinal measures of sputum eosinophils

BACKGROUND

Airway inflammatory phenotyping is increasingly applied to subjects with asthma. However, its relationship to clinical outcomes in difficult asthma is incompletely elucidated.

OBJECTIVE

The goal of our study was to determine the relationship between exacerbation rates and phenotypes of difficult asthma based on the longitudinal measures of sputum eosinophils and neutrophils.

METHODS

Subjects in the longitudinal observational study from two tertiary care centres that completed 1 year of observation and provided at least three sputum samples were classified by inflammatory phenotypes using previously established thresholds. Kaplan-Meier curves and univariable and multivariable Cox proportional hazard models were used to determine the association between inflammatory phenotypes and exacerbation rate.

RESULTS

During the study, 115 exacerbations occurred in 73 severe asthmatic subjects. Subjects with the persistently eosinophilic phenotype had a significantly shorter time to first exacerbation and greater risk of exacerbation over a 1-year period than those with the non-eosinophilic phenotype based on the univariable and multivariable Cox proportional hazard model (hazard ratio [HR], 3.24; 95% confidence interval [CI], 1.35-7.72; adjusted HR, 3.90; 95% CI, 1.34-11.36). No significant differences in time to first exacerbation or exacerbation risk over a 1-year period were observed among the neutrophilic phenotypes.

CONCLUSIONS

The persistent eosinophilic phenotype is associated with increased exacerbation risk compared with the non-eosinophilic phenotype in severe asthma. No differences in time to first exacerbation or exacerbation risk over a 1-year period were detected among neutrophilic phenotypes.

Phenotyping of difficult asthma using longitudinal physiological and biomarker measurements reveals significant differences in stability between clusters

Background

Although the heterogeneous nature of asthma has prompted asthma phenotyping with physiological or biomarker data, these studies have been mostly cross-sectional. Longitudinal studies that assess the stability of phenotypes based on a combination of physiological, clinical and biomarker data are currently lacking.

Our objective was to assess the longitudinal stability of clusters derived from repeated measures of airway and physiological data over a 1-year period in moderate and severe asthmatics.

Methods

A total of 125 subjects, 48 with moderate asthma (MA) and 77 with severe asthma (SA) were evaluated every 3 months and monthly, respectively, over a 1-year period. At each 3-month time point, subjects were grouped into 4 asthma clusters (A, B, C, D) based on a combination of clinical (duration of asthma), physiological (FEV₁ and BMI) and biomarker (sputum eosinophil count) variables, using k-means clustering.

Results

Majority of subjects in clusters A and C had severe asthma (93 % of subjects in cluster A and 79.5 % of subjects in cluster C at baseline). Overall, a total of 59 subjects (47 %) had stable cluster membership, remaining in clusters with the same subjects at each evaluation time. Cluster A was the least stable (21 % stability) and cluster B was the most stable cluster (71 % stability). Cluster stability was not influenced by changes in the dosage of inhaled corticosteroids.

Conclusion

Asthma phenotyping based on clinical, physiologic and biomarker data identified clusters with significant differences in longitudinal stability over a 1-year period. This finding indicates that the majority of patients within stable clusters can be phenotyped with reasonable accuracy after a single measurement of lung function and sputum eosinophilia, while patients in unstable clusters will require more frequent evaluation of these variables to be properly characterized.

Preoperative mapping of fistula-in-ano: a new three-dimensional MRI-based modelling technique

AIM

We aimed to develop an intuitive, interactive, three-dimensional (3D) MRI modelling technique to produce a 3D image of fistula-in-ano.

METHOD

The 3D model was created from standard two-dimensional (2D) MRI sequences to produce an image that is anatomically correct. Individual muscle and soft-tissue layers were extracted from T1-weighted sequences and fistula pathology from short TI inversion recovery (STIR) sequences, to produce two separate volumes. These were then fused using postprocessing software (Vitrea Workstation version 6.3) to generate a 3D model.

RESULTS

The final 3D model was incorporated into a PDF file that has an integrated computer aided design (CAD) viewer, allowing the surgeon to rotate it in any direction during preoperative planning or whilst in theatre.

CONCLUSION

As an adjunct to 2D MRI images and the associated radiology report, this model communicates the fistula anatomy to the clinician more clearly and should be particularly useful in complex cases.

Corticosterone levels of Atlantic puffins vary with breeding stage and sex but are not elevated in poor foraging years

Corticosterone (CORT) levels in seabirds fluctuate across breeding stages and in different foraging conditions. Here we use a ten-year data set to examine whether CORT levels in Atlantic puffins differ in years with high or low availability of capelin, the preferred forage species. Female puffins had higher CORT levels than males, possibly related to cumulative costs of egg production and higher parental investment. Puffins had higher CORT levels and body mass during pre-breeding than during chick rearing. Yearly mean chick growth rates were higher in years when adults had higher body mass and in years where adults brought chicks a lower percentage of non-fish (invertebrates/larval fish) food. Unlike most results from seabird species with shorter chick-rearing periods, higher CORT levels in puffins were not associated with lower capelin abundance. Puffins may suppress CORT levels to conserve energy in case foraging conditions improve later in the prolonged chick-rearing period. Alternatively, CORT levels may be lowest both when food is very abundant (years not in our sample) or very scarce (e.g., 2009 in this study), and increase when extra foraging effort will increase foraging efficiency (most years in this study). If these data primarily represent years with medium to poor foraging, it is possible that CORT responses to variation in foraging conditions are similar for puffins and other seabirds.

Ileostomy formation does not prolong hospital length of stay after open anterior resection when performed within an enhanced recovery programme

AIM

Previous studies have implicated stoma formation as an independent factor prolonging length of stay (LOS) after colorectal surgery. We examined whether loop ileostomy (LI) formation during an open anterior resection affected LOS within a newly developed enhanced recovery programme (ERP). This involved reorganization of services, including stoma care, to optimize pre- and perioperative patient education, training and expectation, while applying the standard scientific principles of enhanced recovery.

METHOD

Data were collected prospectively on 72 consecutive open anterior resections (33 with LI) to see whether LI affected LOS. Stomas were fashioned at the surgeon's discretion and patients were discharged according to agreed criteria.

RESULTS

Thirty-three of the 72 patients had a covering LI performed. The overall age range was 32-85 years (median 68), with 40 patients being men. LOS for all 72 patients ranged from 3 to 34 days. The median and mean LOS were the same for both groups (median 6 days, mean 8 days). The complication rate was 44% (32/72) with a leak rate of 7% (5/72) and a mortality of 1.4% (1/72). Between the two groups (no ileostomy vs ileostomy), there was no statistically significant difference in complications (41%vs 48%), leakage (8%vs 6%) and readmission rates (12%vs 5%).

CONCLUSION

A covering loop ileostomy need not prolong hospital stay after open anterior resection.

Postoperative arrhythmias in colorectal surgical patients: incidence and clinical correlates

OBJECTIVE

To determine the incidence and clinical correlates of postoperative cardiac arrhythmias in patients undergoing elective large bowel resection.

METHODS

Fifty-one consecutive patients undergoing elective open colorectal resection were recruited for this prospective observational study. Participating patients underwent daily three-lead electrocardiograms postoperatively. Data regarding potential risk factors for arrhythmias were recorded. Post-operative complications were recorded.

RESULTS

Thirteen (26%) patients developed a postoperative arrhythmia, most commonly atrial fibrillation. Significant univariate correlates with postoperative arrhythmias were: age (P<0.01), hypertension (P<0.01), pre-operative serum potassium levels (P<0.01), postoperative pulmonary oedema (P=0.03), postoperative serum potassium (P=0.03) and sodium (P<0.01). Arrhythmia patients were more likely to have other complications (P=0.02). Thirty-one percent of arrhythmia patients had underlying sepsis compared with 18% of controls (P=0.38).

CONCLUSION

Arrhythmias are common following elective large bowel resection. They occur in older patients and are associated with the development of other complications.

Intravenous fluid-associated morbidity in postoperative patients

INTRODUCTION

There is marked variation in postoperative fluid prescribing which may contribute to postoperative morbidity. However, there are few data regarding the overall incidence of fluid associated morbidity in postoperative patients.

PATIENTS AND METHODS

Data regarding fluid and electrolyte prescription, fluid balance and intravenous fluid associated morbidity were prospectively collected from 71 patients representing 173 patient days of intravenous fluid therapy.

RESULTS

There was no correlation between fluid and electrolytes prescription and pre-operative weight, serum electrolyte levels or ongoing fluid losses. 17% of patients developed significant fluid associated morbidity. 7 patients developed a tachyarrhythmia, which was associated with the prescription of inadequate maintenance potassium. 5 patients developed fluid overload, associated with excessive fluid volume and sodium administration.

CONCLUSIONS

Surgical house-staff do not appear to use the available fluid balance information when prescribing. The introduction of fluid prescribing protocols may improve practice. This study provides an accurate measure of fluid-associated morbidity in order to measure the efficacy of such protocols.

PSORTb v.2.0: Expanded prediction of bacterial protein subcellular localization and insights gained from comparative proteome analysis

MOTIVATION

PSORTb v.1.1 is the most precise bacterial localization prediction tool available. However, the program's predictive coverage and recall are low and the method is only applicable to Gram-negative bacteria. The goals of the present work are as follows: increase PSORTb's coverage while maintaining the existing precision level, expand it to include Gram-positive bacteria and then carry out a comparative analysis of localization.

RESULTS

An expanded database of proteins of known localization and new modules using frequent subsequence-based support vector machines was introduced into PSORTb v.2.0. The program attains a precision of 96% for Gram-positive and Gram-negative bacteria and predictive coverage comparable to other tools for whole proteome analysis. We show that the proportion of proteins at each localization is remarkably consistent across species, even in species with varying proteome size.

AVAILABILITY

Web-based version: http://www.psort.org/psortb. Standalone version: Available through the website under GNU General Public License.

CONTACT

psort-mail@sfu.ca, brinkman@sfu.ca

SUPPLEMENTARY INFORMATION

http://www.psort.org/psortb/supplementaryinfo.html.

Dexamethasone-induced apoptosis in immune cells from peripheral circulation and lymphomyeloid tissues of juvenile clearnose skates, Raja eglanteria

Juvenile clearnose skates (Raja eglanteria) were injected intramuscularly with dexamethasone-21-phosphate at 50, 75, and 100mg/kg body weight. After 24h, skates were sacrificed and lymphomyeloid tissues (thymus, spleen, Leydig organ, and epigonal organ) were removed and whole blood was sampled. Tissues were used fresh for imprints or prepared for histology by solvent fixation or freezing in liquid nitrogen. Apoptosis in fixed tissues was assessed by transmission electron microscopy. Frozen sections and cytospin preparations of peripheral blood leukocytes (PBL) were evaluated by the TUNEL reaction to detect DNA strand breaks. Dexamethasone treatment increased apoptotic activity in all lymphomyeloid tissues as well as in PBL. These studies demonstrate that immune cells of elasmobranchs have the capacity for glucocorticoid-driven apoptosis, and that programmed cell death as a mechanism to regulate immune cell production appears to have been conserved during vertebrate evolution.

Complex expression patterns of lymphocyte-specific genes during the development of cartilaginous fish implicate unique lymphoid tissues in generating an immune repertoire

Cartilaginous fish express canonical B and T cell recognition genes, but their lymphoid organs and lymphocyte development have been poorly defined. Here, the expression of Ig, TCR, recombination-activating gene (Rag)-1 and terminal deoxynucleosidase (TdT) genes has been used to identify roles of various lymphoid tissues throughout development in the cartilaginous fish, Raja eglanteria (clearnose skate). In embryogenesis, Ig and TCR genes are sharply up-regulated at 8 weeks of development. At this stage TCR and TdT expression is limited to the thymus; later, TCR gene expression appears in peripheral sites in hatchlings and adults, suggesting that the thymus is a source of T cells as in mammals. B cell gene expression indicates more complex roles for the spleen and two special organs of cartilaginous fish-the Leydig and epigonal (gonad-associated) organs. In the adult, the Leydig organ is the site of the highest IgM and IgX expression. However, the spleen is the first site of IgM expression, while IgX is expressed first in gonad, liver, Leydig and even thymus. Distinctive spatiotemporal patterns of Ig light chain gene expression also are seen. A subset of Ig genes is pre-rearranged in the germline of the cartilaginous fish, making expression possible without rearrangement. To assess whether this allows differential developmental regulation, IgM and IgX heavy chain cDNA sequences from specific tissues and developmental stages have been compared with known germline-joined genomic sequences. Both non-productively rearranged genes and germline-joined genes are transcribed in the embryo and hatchling, but not in the adult.

Calibration of a 300-mm-aperture phase-shifting Fizeau interferometer

A 300-mm-aperture digital phase-shifting Fizeau interferometer has been developed in-house for precision metrology of optical components fabricated by the optical workshop at Telecommunications and Industrial Physics, Commonwealth Scientific and Industrial Research Organization. We describe the procedures used in the calibration of the instrument. A reference data file representing the deviations from flatness of the reference surface is generated, measurement uncertainty estimated, and aberrations in the instrument assessed. Measurements on 250-mm-diameter uncoated optical surfaces have consistently shown short-term repeatability of 0.3-nm rms from measurement to measurement and allowed for absolute characterization of these surfaces to within a few nanometers.

Meniscus regeneration in a rabbit partial meniscectomy model

Meniscectomy is known to be associated with osteoarthrosis of the knee. The purpose of this study was to compare the natural and augmented repair of menisci in the knees of New Zealand White rabbits. To create a partial defect in the medial meniscus, we used an experimental model that has been well characterized and extensively used in the study of osteoarthrosis and articular cartilage repair. The defect was left untreated or treated with one of the following: a periosteal autograft, a type I collagen sponge, or the same sponge loaded with autologous, bone marrow-derived, cultured mesenchymal stem cells. The natural repair was always incomplete and degenerative changes within these joints were progressive. The periosteal autograft underwent differentiation into a bone and hyaline cartilage composite that was ineffectual as a meniscus and accelerated the degenerative changes in those joints when compared to natural repair controls. There was evidence of a consistent sequence of events in the transformation of the periosteal grafts to a core of cartilage that underwent endochondral ossification. In the last two groups, the collagen sponge functioned as a scaffold that resulted in more abundant repair tissue. The collagen sponge alone supported a largely fibrous repair process. The cultured mesenchymal stem cells were observed to augment the repair process in some specimens to include fibrocartilage histologically similar to normal meniscus. Degenerative changes were present in both of these groups, which indicates that the biomechanical function of the meniscus was not restored, or an irreversible osteoarthrosis cascade was initiated during the repair period. Based on these preliminary studies, further investigation of cell-based meniscus regeneration appears to be warranted.

Power spectral density analysis of optical substrates for gravitational-wave interferometry

The power spectral density of surface-relief variations on polished optical surfaces across microscopic through to macroscopic spatial scales is calculated from measurements on substrates that are being produced for the Laser Interferometer Gravitational-Wave Observatory (LIGO). These spectra give a guide to the scattering properties of the surface, which in turn critically influence the performance of LIGO. Measurements obtained by use of a full-aperture interferometer and an interference microscope with two different objectives are combined to produce one-dimensional power spectral density representations of the surfaces across spatial frequencies ranging from 0.1 to 8000 cm(-1). These measurements from different instruments are in good agreement with an analytic power spectrum that varies as nu(-1.5), where nu is the spatial frequency. Some anomalies in the power spectral density spectra can be related to aspects of the polishing process.

Fabrication and measurement of optics for the laser interferometer gravitational wave observatory

The manufacture and testing of high-precision optical surfaces for the Laser Interferometer Gravitational Wave Observatory is described. Through the use of carefully shaped polishing laps made of a nondeformable polymer material coated on a rigid base, surfaces 250 mm in diameter with radii of curvature between 7 and 15 km were polished to an accuracy of several hundred meters in the curvature and with low values of waviness and microroughness. Metrology instrumentation used to measure the optical finish included a large-aperture digital interferometer calibrated to nanometer-level accuracy for measurements of curvature, astigmatism, and waviness and an interference microscope for measurements of microroughness. The power spectra of the data from both instruments were in good agreement.

Hippocampal volume is related to complexity of nesting habitat in Leach's storm-petrel, a nocturnal procellariiform seabird

The hippocampal and telencephalon volumes of the nocturnal Leach's storm-petrel (Oceanodroma leucorhoa, n = 15) were compared with published data for food-storing and non-storing Passerines. The hippocampus to telencephalon ratio of Leach's storm-petrels is intermediate between food-storing and non-storing birds. Leach's storm-petrels taken from nesting burrows in wooded habitat had a larger relative hippocampal volume than those taken from burrows in an open meadow. Relative olfactory volume did not differ between woods and open-nesting storm-petrels. The larger relative hippocampal volume of storm-petrels may be associated with increased spatial demands of returning to their nests at night in the darker, more navigationally complex woods. It is not known whether the larger hippocampus in storm-petrels from the woods is due to selection on different subpopulations or whether experience in a more complex environment results in greater hippocampal volume. Hippocampal volume from the brain of one diurnal Procellariiforme, the northern fulmar (Fulmaris glacialis), fell within the range of non-storing species, which supports the view that hippocampal enlargement in the storm-petrel is related to the spatial demand of returning to the nest at night.

Cloning, sequencing, and nucleolar targeting of the basal-body-binding nucleolar protein BN46/51

BN46/51 is an acidic protein found in the granular component of the nucleolus of the amebo-flagellate Naegleria gruberi. When Naegleria amebae differentiate into swimming flagellates, BN46/51 is found associated with the basal body complex at the base of the flagella. In order to determine the factors responsible for targeting BN46/51 to a specific subnucleolar region, cDNAs coding for both subunits were isolated and sequenced. Two clones, JG4.1 and JG12.1 representing the 46 kDa and 51 kDa subunits, respectively, were investigated in detail. JG12.1 encoded a polypeptide of 263 amino acids with a predicted size of 30.1 kDa that co-migrated with the 51 kDa subunit of BN46/51 when expressed in yeast. JG4.1 encoded a polypeptide of 249 amino acids with a predicted size of 28.8 kDa that co-migrated with the 46 kDa subunit of BN46/51. JG4.1 was identical to JG12.1 except for the addition of an aspartic acid between positions 94 and 95 of the JG12.1 sequence and the absence of 45 amino acids beginning at position 113. The predicted amino acid sequences were not closely related to any previously reported. However, the sequences did have 26–31% identity to a group of FKPBs (FK506 binding proteins) but lacked the peptidyl-prolyl cis-trans isomerase domain of the FKBPs. Both subunits contained two KKE and three KKX repeats found in other nucleolar proteins and in some microtubule binding proteins. Using ‘Far Western’ blots of nucleolar proteins, BN46/51 bound to polypeptides of 44 kDa and 74 kDa. The 44 kDa component was identified as the Naegleria homologue of fibrillarin. BN46/51 bound specifically to the nucleoli of fixed mammalian cells, cells which lack a BN46/51 related polypeptide. When the JG4.1 and JG12.1 cDNAs were expressed in yeast, each subunit was independently targeted to the yeast nucleolus. We conclude that BN46/51 represents a unique nucleolar protein that can form specific complexes with fibrillarin and other nucleolar proteins. We suggest that the association of BN46/51 with the MTOC of basal bodies may reflect its role in connecting the nucleolus with the MTOC activity for the mitotic spindle. This would provide a mechanism for nucleolar segregation during the closed mitosis of Naegleria amebae.

Design of a lithium niobate Fabry-Perot étalon-based spectrometer

The design of a tunable Fabry-Perot étalon-based filter that has a passband of 0.01 nm and a free spectral band larger than 50 nm when operated in the center of the visible spectrum is described. The filter consists of two Y-cut lithium niobate étalons having thicknesses in a vernier ratio. The polarization state of light passing through the tandem étalons is rotated 90 degrees before again being transmitted through the étalon pair. If the components are arranged in a symmetrical manner, the filter will operate with unpolarized incident light. Each étalon in double pass will have a greater transmittance than two individual étalons of the same average optical thicknesses, since variations in the physical thickness due to fabrication errors are correlated.

Evaluation of p53 protein expression in renal cell carcinoma: comparison of two antibodies

The aims of this study were to establish a profile for the expression of p53 in primary renal cell carcinoma using the polyclonal antibody NCL-CB1 and the monoclonal antibody D07, and to compare the results of staining with both antibodies. Ninety-six cases were studied using formalin-fixed paraffin-embedded tissue. Positive nuclear staining ranged from 5% (D07) to 12% (NCL-CM1). Positive cytoplasmic staining ranged from 7% (D07) to 25% (NCL-CM1) of cases. Interobserver agreement was excellent. The findings suggest that such a low level of immunohistochemical positivity reduces any potential prognostic value for p53 in this tumour type.

Laparoscopic common bile duct exploration: evolution of a new technique

Laparoscopic exploration of the common bile duct (CBD) with a choledochoscope or a stone basket during laparoscopic cholecystectomy was attempted in 60 patients and was successful in 56. The cystic duct was used for entry to the CBD in 46 patients and in 14 a choledochotomy was performed. Of 51 patients with confirmed common duct stones, 38 had complete laparoscopic clearance (75 per cent). In 13 patients the duct was not cleared or was only partially cleared, of whom four went on to have clearance by postoperative percutaneous choledochoscopy down a cystic duct or T-tube track. Two patients with cystic duct tubes passed their remaining stones spontaneously. One patient had open exploration and six required endoscopic retrograde cholangiopancreatography. Of nine patients without stones, choledochoscopy was impossible in three patients whose cholangiogram was later considered to be normal. In five patients stones were excluded by choledochoscopy and in one patient laparoscopic choledochoscopy was undertaken to better define abnormal biliary anatomy; this helped to avoid major bile duct injury. Choledochoscopy was easier with the smaller 3.6-mm ureteroscope but stone removal was more difficult when the basket was too small for the stones, the cystic duct too small relative to stone size or the number of stones was too great. Successful stone clearance was proportional to the level of effort expended, and was limited by operating time and equipment.

The effects of olfactory and somatosensory desensitization on Fos-like immunoreactivity in the brains of pup-exposed postpartum rats

Fos-like immunoreactivity (fos-lir) was examined in sites within the "maternal circuit" in postpartum female rats that received various sensory desensitizations and were exposed to pups for 1 or 2 hr. Neither olfactory bulbectomy nor thelectomy (nipple removal) significantly reduced the fos-lir in the anterior medial preoptic area (MPOA), although reductions following bulbectomy in medial amygdala did occur. Peripherally induced hyposmia by ZnSo4 reduced fos-lir in the olfactory structures (olfactory bulbs, piriform cortex, and olfactory tubercle), in medial and cortical nuclei of the amygdala, but not in anterior MPOA. Application of the topical anesthetic Emla to the ventrum only reduced fos-lir in the somatosensory cortex. Combined olfactory and ventral desensitizations produced marginal reductions in posterior MPOA. It is suggested that the MPOA is primarily involved as part of the effector system in the expression of the behavior. In contrast, the amygdala is involved in processing sensory cues received from pups during dam-litter interactions.

Incidence of third-degree perineal tears in labour and outcome after primary repair

The incidence and outcome of third-degree tears following 16,583 vaginal deliveries were prospectively assessed over a 5.5-year period. Ninety-three deliveries (0.56 per cent) were complicated by a third-degree tear and the patients underwent primary repair. Eighty-one patients were reviewed 3 months postpartum at a colorectal clinic. Third-degree tears were significantly more common in primigravidae and mothers with higher birth-weight babies. They were significantly associated with the use of forceps and were not prevented by episiotomy. Of the 81 patients reviewed, 30 had an abnormal anorectal examination. Six patients (7 per cent) were incontinent of faeces. A further ten (12 per cent) were incontinent of flatus only. The overall incidence of faecal incontinence was 0.04 per cent. An important group of women with significant subclinical sphincter injury was identified. Obstetric trauma causes significant anorectal dysfunction and patients with third-degree tears require assessment by a colorectal specialist.

Tumor necrosis factor-alpha and interleukin-6 selectively regulate neutrophil function in vitro

The neutrophil is an important effector cell of the host response to sepsis. Tumor necrosis factor-alpha (TNF-alpha), a cytokine mediator of the septic response, is rapidly released following endotoxemia or gram-negative bacteremia. Interleukin-6 (IL-6) is another cytokine mediator of the host response to sepsis whose role is less well understood than that of TNF-alpha. It is known to be elevated in gram-negative sepsis, where peak levels have been correlated with mortality. This study examined the effect of IL-6 alone and in combination with TNF-alpha on three neutrophil functions--CD18 adhesion receptor expression, phagocytosis, and superoxide anion generation. Neutrophils from human volunteers were incubated with amounts of IL-6 ranging from 10 to 1000 ng/ml. At a concentration of 1000 ng/ml, IL-6 increased neutrophil phagocytosis of opsonized bacteria (826 +/- 255 x 10(3) MESF vs 552 +/- 103 MESF, P < 0.05) and also increased neutrophil superoxide anion generation (18.41 +/- 1.86 vs 12.6 nmol O2-/10(6) PMN/10 min, P < 0.05). Lesser amounts of IL-6 had no effect on phagocytosis or superoxide generation. IL-6 did not increase neutrophil CD18 adhesion receptor expression. Combining IL-6 with TNF-alpha at doses of 100 ng/ml and 100 U/ml, respectively, neutrophil phagocytosis (221 +/- 455 MESF vs 552 +/- 103 MESF) and superoxide generation (23.18 +/- 1.86 vs 12.6 nmol O2-/10(6) PMN/10 min) were significantly (P < 0.05) increased above control by an amount similar to that seen with 1000 U/ml TNF-alpha alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Multi-agent therapy in the treatment of sepsis-induced microvascular injury

Cyclo-oxygenase inhibition (with ibuprofen) combined with histamine (H1, H2) receptor antagonism (with diphenhydramine and cimetidine) attenuates microvascular leak injury in sepsis syndromes. Ibuprofen reduces microvascular injury by limiting oxygen radical production by neutrophils. Histamine is known to inhibit this oxygen radical production, an effect antagonized by cimetidine. In the present study neutrophils isolated from pigs made septic with Pseudomonas organisms exhibited a significant (P < 0.05) increase in the production of the oxygen radicals, superoxide anion (O2-, 133 per cent) and hypochlorous acid (HOCl, 38 per cent). Ibuprofen used alone attenuated this sepsis-stimulated overproduction. Addition of the antihistamines cimetidine and diphenhydramine produced a significant increase in oxygen radical production (P < 0.05), by 122 per cent (O2-) and 47 per cent (HOCl), equivalent to that in untreated septic animals. This coincided with a significant deterioration in pulmonary compliance (P < 0.05) compared with that found in control animals and those treated with ibuprofen alone, and a significant accumulation of extravascular lung water (P < 0.05) at 240 and 300 min versus baseline. Histamine receptor antagonism may inadvertently enhance microvascular injury in sepsis.

Monoclonal antibody to tumor necrosis factor-alpha attenuates plasma interleukin-6 levels in porcine gram-negative sepsis

This study examined the kinetics of IL-6 release into the systemic circulation in a porcine model of bacterial sepsis induced by infusion of live Pseudomonas aeruginosa. Three groups of animals were studied. Group I (n = 12) animals received a 1 hr infusion of live P. aeruginosa. Group II (n = 6) animals received monoclonal antibody to tumor necrosis factor-alpha (TNF-alpha) (15 mg/kg) prior to induction of sepsis. Group III (n = 7) animals received sterile saline only. TNF-alpha and interleukin-6 (IL-6) levels rose sharply, in group I following pseudomonas infusion. Following a peak at 120 min after the bacterial infusion (4.8 +/- 0.7 U/ml at 120 min vs 0.4 +/- 0.2 U/ml at 0 min), TNF-alpha levels subsequently declined prior to the end of the experiment. In contrast, IL-6 levels rose sharply, subsequent to TNF-alpha, peaked at 180 min, and remained significantly elevated throughout the study period (5.3 +/- 0.9 ng/ml vs 0.05 +/- 0.01 ng/ml, 0 min). In animals pretreated with monoclonal antibody to TNF-alpha, no increase in TNF-alpha activity was detected at any time during the period of study. IL-6 levels in antibody-treated animals, although greatly attenuated, still rose significantly above baseline (2.02 +/- 0.8 ng/ml at 180 min vs 0.05 +/- 0.01 ng/ml at 0 min) and above levels in control animals. We conclude that although TNF-alpha plays an important role in synthesis and release of IL-6, there is a TNF-alpha-independent pathway for release of IL-6 in sepsis.

C-erbB-2 immunostaining: problems with interpretation

AIMS

To assess the consistency and reproducibility of assessment of c-erbB-2 immunostaining, and to examine some of the problems relating to inter- and intraobserver variability in the documentation of positive staining; to profile the spectrum of cytoplasmic and membranous staining in a wide range of tumour types.

METHODS

A total of 283 neoplasms were examined for immunohistochemical expression of the c-erbB-2 oncoprotein. Three independent observers were required to assess intensity both of membrane and cytoplasmic staining on a three point and then a four point scale. Extent of positive staining was also assessed on a two point scale. A minimum of two weeks elapsed between assessments using the differing scales.

RESULTS

Positive membrane staining was documented by one or more observers in 16.6% of tumours examined. This positivity was largely restricted to bladder, renal, and breast tumours. The overall level of disagreement as to the presence or absence of membranous staining was 11.3%. Cytoplasmic staining was identified in 55.5% of tumours studied. The level of disagreement as to the presence or absence of cytoplasmic staining was 26.5%.

CONCLUSIONS

Intraobserver variability was minimal, indicating that each pathologist was adhering to internal reproducible standards. Interobserver variability was greater, indicating that the interpretation of c-erbB-2 immunostaining may require set guidelines. It is suggested that assessment should be referenced to a standard positive control, that a three tier system for grading of intensity and a two tier system for grading of extent should be adopted, and that the evaluation should be agreed by at least two pathologists. The presence of cytoplasmic staining should continue to be routinely recorded until its biological role and clinical implications are fully understood.

Differential activation of alveolar, pulmonary arterial, and systemic arterial neutrophils demonstrates the existence of distinct neutrophil subpopulations in experimental sepsis

Neutrophils (PMNs) are considered key cellular mediators of sepsis induced acute lung injury. PMN activation is manifest by increased beta 2 integrin expression and enhanced superoxide radical (O2-) generation. What is unclear is at which anatomical sites PMNs are activated and at which sites they release O2- and mediate lung injury. In this study we compared alveolar (ALV), systemic arterial (SA), and pulmonary arterial (PA) PMNs CD18 receptor expression, measured by fluorescent immunophenotyping and, O2- generation, measured by reduction of ferricytochrome C, in septic swine. Swine were anesthetized and ventilated, and given a 1-h infusion of live Pseudomonas aeruginosa. PA, SA, and ALV PMNs were isolated at 0 and 5 h. ALV PMNs O2- was reduced compared to SA blood PMNs O2- at 5 h, (AIV 5 h 23.6 +/- 3 vs. SA 0 h 34.3 +/- 5, p < .05). SA PMNs O2- generation was also significantly reduced compared to PA PMNs at 5 h (PA 5 h 21 +/- 2.5 vs. SA 5 h 16.9 +/- 2.6, p < .05). Alv PMNs expressed significantly greater CD18 receptor levels than SA blood PMNs at 5 h (AIV PMNs 5 h, 76 +/- 6 vs. SA PMNs 5 h 51 +/- 3, p < .05), however, PA PMNs CD18 receptor levels were not significantly different from SA PMNs levels at 5 h. These data corroborate a dissociation between two PMN functions in sepsis. O2- generation was reduced across the lung and following migration. However, alveolar PMNs had significantly upregulated CD18 expression compared to PMNs in PA and SA.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed tumor necrosis factor alpha blockade attenuates pulmonary dysfunction and metabolic acidosis associated with experimental gram-negative sepsis

OBJECTIVE

To ascertain the effect of delayed tumor necrosis factor alpha (TNF-alpha) on the evolution of systemic and pulmonary injury after the onset of sepsis.

DESIGN

Prospective controlled trial.

INTERVENTION

Anesthetized swine were made septic with a 1-hour infusion of live Pseudomonas aeruginosa, following which a treatment group received an infusion of anti-TNF-alpha monoclonal antibody (5 mg/kg). Control animals received 0.9% saline.

RESULTS

Delayed anti-TNF-alpha treatment had no effect on septic pulmonary hypertension or decline in cardiac output. Late recovery in systemic arterial hypotension was associated with a reversal of arterial acidosis (P < .05 by t test and analysis of variance with Tukey's Studentized Range Test) compared with unprotected septic animals. Septic animals had a significant increase in mean (+/- SEM) plasma lactate levels at 5 hours compared with baseline values (3.8 +/- 0.7 vs 2 +/- 0.4, P < .05), but remained unchanged from baseline following anti-TNF-alpha treatment (1.5 +/- 0.1 vs 1.6 +/- 0.2, not significant). Characteristic septic neutropenia was dramatically reversed by anti-TNF-alpha treatment and was associated with downregulation (P < .05 by t test and analysis of variance) of polymorphonuclear neutrophil (PMN) leukocyte CD18 adhesion receptors and reduction (P < .05 by t test and analysis of variance) in lung PMN sequestration measured by myeloperoxidase activity. The mean (+/- SEM) decrease in bronchoalveolar lavage protein indicated an attenuated permeability injury in anti-TNF-alpha animals (septic animals at 5 hours compared with baseline value, 1044 +/- 270 vs 149 +/- 28 micrograms/mL; control animals at 5 hours compared with baseline value, 217 +/- 83 vs 129 +/- 19 micrograms/mL; P < .05 by t test and analysis of variance).

CONCLUSIONS

These data show that delayed anti-TNF-alpha treatment reversed metabolic acidosis associated with sepsis. Furthermore, anti-TNF-alpha treatment reversed septic neutropenia, reduced PMN sequestration, and was associated with attenuated lung injury in a model of fulminant sepsis. This supports evidence of PMN-mediated tissue injury in sepsis and suggests mechanisms for potential therapeutic benefit of anti-TNF-alpha treatment in clinical practice.

Nucleolus-like morphology produced during the in vitro reassociation of nucleolar components

Nucleoli, the sites of rRNA synthesis, rRNA processing, and the assembly of ribosomes, are dynamic organelles that, in most cells, disperse and reform during mitosis. The mechanisms that regulate nucleolar formation are unknown as is the relationship between nucleolar morphology and the pathway of ribosome biogenesis. In this report we describe the in vitro formation of nucleolus-like particles (NLPs) from soluble extracts of nucleoli. NLPs, which reached sizes comparable to nucleoli (1-3 microns), were found to contain 40% of the nucleolar DNA, RNA, and protein. The ultrastructure of NLPs resembled that of a number of in vivo structures including compact nucleoli, prenucleolar bodies, and pseudonucleoli. The particles were composed of two morphologically distinct regions. The core resembled the dense fibrillar component (DFC) of nucleoli while the cortex resembled the granular component (GC) of nucleoli. The cortex of NLPs contained numerous 15-20 nm osmophilic granules that resembled the preribosomes found in the GC of nucleoli. The distribution of nucleolar proteins in NLPs also resembled that in nucleoli. BN46/51, a component of the GC of nucleoli, was restricted to the GC-like cortex of NLPs. A mAb that bound to the DFC of nucleoli, bound only to the DFC-like core of NLPs while a second mAb that bound to both the DFC and GC of nucleoli, bound to both the core and cortex of NLPs. Thus solubilized components of nucleoli can reassociate in vitro to produce particles that resemble nucleoli in their size, ultrastructure, and protein distribution.

Combined ibuprofen and monoclonal antibody to tumor necrosis factor-alpha attenuate hemodynamic dysfunction and sepsis-induced acute lung injury

A number of key mediators are implicated in the pathophysiology of sepsis. In previous studies of a septic porcine model, ibuprofen pretreatment prevented the early but not the late rise in pulmonary vascular resistance index (PVRI) and the early but not the late fall in arterial PO2 (PaO2), whereas monoclonal antibody to tumor necrosis factor alpha (anti-TNF alpha) prevented the late but not the early rise in PVRI and the late but not the early fall in PaO2. This study examined the impact of pretreatment with combined ibuprofen and anti-TNF-alpha on the course of sepsis and acute lung injury (ALI) in pigs. Three groups were studied for 5 hours. Groups I (n = 9) and II (n = 5) received a 1-hour infusion of Pseudomonas aeruginosa. Group II received ibuprofen (12.5 mg/kg) and anti-TNF-alpha (5 mg/kg) before P. aeruginosa, and a further bolus of ibuprofen at 120 minutes. Group III (n = 11) received sterile saline. Group I demonstrated a significant (p < 0.05) rise in plasma TNF-alpha that was abolished in group II. The SVRI in group II did not change significantly from baseline through the study and the SVRI rose sharply in group I following onset of the infusion of P. aeruginosa, as did PVRI. There was no significant change in PVRI from baseline in group II, except for the final 60 minutes; PVRI in group II was significantly less than in group I throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)