Imaging perturbed shock propagation in powders

A novel experimental methodology is presented to study the deviatoric response of powders in shock regimes. The powders are confined to a cylindrical wedge volume, and a projectile-driven shock wave with a sinusoidally varying front propagates through the powder. The perturbed shock wave exhibits a damping behavior due to irreversible processes of viscosity and strength (deviatoric) of the powder with propagation through increasing powder thicknesses. The inclined surface of the wedge is polished and coated to establish a diffuse surface suitable for reflecting incident laser light into a high-speed camera imaging at 5 MHz. Images of the contrast loss upon shock wave arrival at the observation surface are post-processed for qualitative and quantitative information. New data of shock damping behavior with parameters of perturbation wavelength and initial shock strength are presented for powders of copper, tantalum, and tungsten carbide as well as their mixtures. We present the first full-field images showing additional spatial disturbances on the perturbed shock front that appear dependent on particle material and morphology.

Mycobacterium chimaera infection following cardiac surgery in the United Kingdom: clinical features and outcome of the first 30 cases

OBJECTIVES

Mycobacterium chimaera infection following cardiac surgery, due to contaminated cardiopulmonary bypass heater-cooler units, has been reported worldwide. However, the spectrum of clinical disease remains poorly understood. To address this, we report the clinical and laboratory features, treatment and outcome of the first 30 UK cases.

METHODS

Case note review was performed for cases identified retrospectively through outbreak investigations and prospectively through ongoing surveillance. Case definition was Mycobacterium chimaera detected in any clinical specimen, history of cardiothoracic surgery with cardiopulmonary bypass, and compatible clinical presentation.

RESULTS

Thirty patients were identified (28 with prosthetic material) exhibiting a spectrum of disease including prosthetic valve endocarditis (14/30), sternal wound infection (2/30), aortic graft infection (4/30) and disseminated (non-cardiac) disease (10/30). Patients presented a median of 14 months post surgery (maximum 5 years) most commonly complaining of fever and weight loss. Investigations frequently revealed lymphopenia, thrombocytopenia, liver cholestasis and non-necrotizing granulomatous inflammation. Diagnostic sensitivity for a single mycobacterial blood culture was 68% but increased if multiple samples were sent. In all, 27 patients started macrolide-based combination treatment and 14 had further surgery. To date, 18 patients have died (60%) a median of 30 months (interquartile range 20-39 months) after initial surgery. Survival analysis identified younger age, mitral valve surgery, mechanical valve replacement, higher serum sodium concentration and lower C-reactive protein as factors associated with better survival.

CONCLUSIONS

Mycobacterium chimaera infection following cardiac surgery is associated with a wide spectrum of disease. The diagnosis should be considered in all patients who develop an unexplained illness following cardiac surgery.

Evidence against a role for NLRP3-driven islet inflammation in db/db mice

Objectives

Type 2 diabetes (T2D) is associated with chronic, low grade inflammation. Activation of the NLRP3 inflammasome and secretion of its target interleukin-1β (IL-1β) have been implicated in pancreatic β cell failure in T2D. Specific targeting of the NLRP3 inflammasome to prevent pancreatic β cell death could allow for selective T2D treatment without compromising all IL-1β-associated immune responses. We hypothesized that treating a mouse model of T2D with MCC950, a compound that specifically inhibits NLRP3, would prevent pancreatic β cell death, thereby preventing the onset of T2D.

Methods

Diabetic db/db mice were treated with MCC950 via drinking water for 8 weeks from 6 to 14 weeks of age, a period over which they developed pancreatic β cell failure. We assessed metabolic parameters such as body composition, glucose tolerance, or insulin secretion over the course of the intervention.

Results

MCC950 was a potent inhibitor of NLRP3-induced IL-1β in vitro and was detected at high levels in the plasma of treated db/db mice. Treatment of pre-diabetic db/db mice with MCC950, however, did not prevent pancreatic dysfunction and full onset of the T2D pathology. When examining the NLRP3 pathway in the pancreas of db/db mice, we could not detect an activation of this pathway nor increased levels of its target IL-1β.

Conclusions

NLRP3 driven-pancreatic IL-1β inflammation does not play a key role in the pathogenesis of the db/db murine model of T2D.

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Inhibition of NLRP3 via MCC950 in db/db mice did not improve glucose tolerance.

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MCC950 treatment did not prevent beta cell loss of function.

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Expression of IL1beta and NLRP3 does not appear increased in db/db islets.

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We conclude against a role for NLRP3 in db/db pancreatic dysfunction.

Training non-physicians to do endoscopy: Feasibility, effectiveness and cost-effectiveness

Colorectal cancer (CRC) is one of the most common cancers in women and men worldwide. Training non-physicians including nurses, nurse practitioners, and physician assistants to perform endoscopy can provide the opportunity to expand access to CRC screening as demand for endoscopic procedures continues to grow. A formal program, incorporating didactic instruction and hands-on practice in addition to oversight, is required to train non-physicians to perform endoscopy as safely and effectively as physicians. Additionally, the context in which the non-physician endoscopy program is organized will dictate key program characteristics including remuneration, participant recruitment and professional and legal considerations. This review explores the evidence in support of non-physician based endoscopy, potential challenges in implementing non-physician endoscopy and requirements for a high-quality program to support training and implementation.

Gastrointestinal Endoscopy Competency Assessment Tool: reliability and validity evidence

BACKGROUND

Rigorously developed and validated direct observational assessment tools are required to support competency-based colonoscopy training to facilitate skill acquisition, optimize learning, and ensure readiness for unsupervised practice.

OBJECTIVE

To examine reliability and validity evidence of the Gastrointestinal Endoscopy Competency Assessment Tool (GiECAT) for colonoscopy for use within the clinical setting.

DESIGN

Prospective, observational, multicenter validation study. Sixty-one endoscopists performing 116 colonoscopies were assessed using the GiECAT, which consists of a 7-item global rating scale (GRS) and 19-item checklist (CL). A second rater assessed procedures to determine interrater reliability by using intraclass correlation coefficients (ICCs). Endoscopists' first and second procedure scores were compared to determine test-retest reliability by using ICCs. Discriminative validity was examined by comparing novice, intermediate, and experienced endoscopists' scores. Concurrent validity was measured by correlating scores with colonoscopy experience, cecal and terminal ileal intubation rates, and physician global assessment.

SETTING

A total of 116 colonoscopies performed by 33 novice (<50 previous procedures), 18 intermediate (50-500 previous procedures), and 10 experienced (>1000 previous procedures) endoscopists from 6 Canadian hospitals.

MAIN OUTCOME MEASUREMENTS

Interrater and test-retest reliability, discriminative, and concurrent validity.

RESULTS

Interrater reliability was high (total: ICC=0.85; GRS: ICC=0.85; CL: ICC=0.81). Test-retest reliability was excellent (total: ICC=0.91; GRS: ICC=0.93; CL: ICC=0.80). Significant differences in GiECAT scores among novice, intermediate, and experienced endoscopists were noted (P<.001). There was a significant positive correlation (P<.001) between scores and number of previous colonoscopies (total: ρ=0.78, GRS: ρ=0.80, CL: Spearman's ρ=0.71); cecal intubation rate (total: ρ=0.81, GRS: Spearman's ρ=0.82, CL: Spearman's ρ=0.75); ileal intubation rate (total: Spearman's ρ=0.82, GRS: Spearman's ρ=0.82, CL: Spearman's ρ=0.77); and physician global assessment (total: Spearman's ρ=0.90, GRS: Spearman's ρ=0.94, CL: Spearman's ρ=0.77).

LIMITATIONS

Nonblinded assessments.

CONCLUSION

This study provides evidence supporting the reliability and validity of the GiECAT for use in assessing the performance of live colonoscopies in the clinical setting.

Inflammasome activity is essential for one kidney/deoxycorticosterone acetate/salt-induced hypertension in mice

BACKGROUND AND PURPOSE

Inflammasomes are multimeric complexes that facilitate caspase-1-mediated processing of the pro-inflammatory cytokines IL-1β and IL-18. Clinical hypertension is associated with renal inflammation and elevated circulating levels of IL-1β and IL-18. Therefore, we investigated whether hypertension in mice is associated with increased expression and/or activation of the inflammasome in the kidney, and if inhibition of inflammasome activity reduces BP, markers of renal inflammation and fibrosis.

EXPERIMENTAL APPROACH

Wild-type and inflammasome-deficient ASC(-/-) mice were uninephrectomized and received deoxycorticosterone acetate and saline to drink (1K/DOCA/salt). Control mice were uninephrectomized but received a placebo pellet and water. BP was measured by tail cuff; renal expression of inflammasome subunits and inflammatory markers was measured by real-time PCR and immunoblotting; macrophage and collagen accumulation was assessed by immunohistochemistry.

KEY RESULTS

1K/DOCA/salt-induced hypertension in mice was associated with increased renal mRNA expression of inflammasome subunits NLRP3, ASC and pro-caspase-1, and the cytokine, pro-IL-1β, as well as protein levels of active caspase-1 and mature IL-1β. Following treatment with 1K/DOCA/salt, ASC(-/-) mice displayed blunted pressor responses and were also protected from increases in renal expression of IL-6, IL-17A, CCL2, ICAM-1 and VCAM-1, and accumulation of macrophages and collagen. Finally, treatment with a novel inflammasome inhibitor, MCC950, reversed hypertension in 1K/DOCA/salt-treated mice.

CONCLUSIONS AND IMPLICATIONS

Renal inflammation, fibrosis and elevated BP induced by 1K/DOCA/salt treatment are dependent on inflammasome activity, highlighting the inflammasome/IL-1β pathway as a potential therapeutic target in hypertension.

Neurobiological mechanisms supporting experience-dependent resistance to social stress

Humans and other animals show a remarkable capacity for resilience following traumatic, stressful events. Resilience is thought to be an active process related to coping with stress, although the cellular and molecular mechanisms that support active coping and stress resistance remain poorly understood. In this review, we focus on the neurobiological mechanisms by which environmental and social experiences promote stress resistance. In male Syrian hamsters, exposure to a brief social defeat stressor leads to increased avoidance of novel opponents, which we call conditioned defeat. Also, hamsters that have achieved dominant social status show reduced conditioned defeat as well as cellular and molecular changes in the neural circuits controlling the conditioned defeat response. We propose that experience-dependent neural plasticity occurs in the prelimbic (PL) cortex, infralimbic (IL) cortex, and ventral medial amygdala (vMeA) during the maintenance of dominance relationships, and that adaptations in these neural circuits support stress resistance in dominant individuals. Overall, behavioral treatments that promote success in competitive interactions may represent valuable interventions for instilling resilience.

Surgical residents' perceptions on learning gastrointestinal endoscopy: more hours and more standardization wanted

OBJECTIVE

Gastrointestinal endoscopy is a complex task that involves an interaction of cognitive and manual skills. There is no consensus on the optimal way to teach endoscopy. We sought to evaluate our formal endoscopy curriculum for general surgery trainees to improve the effectiveness and quality of the endoscopy teaching in this program.

DESIGN

We conducted focus group sessions over a 2-year period. Participants were general surgery residents, who are at the end of their endoscopy training rotation. The goal was to obtain the opinions and perceptions of trainees actively involved in learning endoscopy.

SETTING

University-based general surgery residency.

PARTICIPANTS

Second-year general surgery residents.

RESULTS

A total of 24 residents participated in 7 focus group sessions over 2 years. Four central themes emerged that included training structure and expectations, development of endoscopy competence, teaching approaches and teaching tools, and recommendations for improvement of the training experience.

CONCLUSIONS

An assessment of the themes led to the following concrete suggestions for improvement: the development of an algorithmic approach to endoscopy for the novice learner, consideration to introduce additional experience in endoscopy later in the 5-year surgery program, and consideration to incorporate a train-the-trainer curriculum for faculty that teach endoscopy.

Pathway-selective antagonism of proteinase activated receptor 2

BACKGROUND AND PURPOSE

Proteinase activated receptor 2 (PAR2) is a GPCR associated with inflammation, metabolism and disease. Clues to understanding how to block PAR2 signalling associated with disease without inhibiting PAR2 activation in normal physiology could be provided by studies of biased signalling.

EXPERIMENTAL APPROACH

PAR2 ligand GB88 was profiled for PAR2 agonist and antagonist properties by several functional assays associated with intracellular G-protein-coupled signalling in vitro in three cell types and with PAR2-induced rat paw oedema in vivo.

KEY RESULTS

In HT29 cells, GB88 was a PAR2 antagonist in terms of Ca(2+) mobilization and PKC phosphorylation, but a PAR2 agonist in attenuating forskolin-induced cAMP accumulation, increasing ERK1/2 phosphorylation, RhoA activation, myosin phosphatase phosphorylation and actin filament rearrangement. In CHO-hPAR2 cells, GB88 inhibited Ca(2+) release, but activated G(i/o) and increased ERK1/2 phosphorylation. In human kidney tubule cells, GB88 inhibited cytokine secretion (IL6, IL8, GM-CSF, TNF-α) mediated by PAR2. A rat paw oedema induced by PAR2 agonists was also inhibited by orally administered GB88 and compared with effects of locally administered inhibitors of G-protein coupled pathways.

CONCLUSIONS AND IMPLICATIONS

GB88 is a biased antagonist of PAR2 that selectively inhibits PAR2/G(q/11)/Ca(2+)/PKC signalling, leading to anti-inflammatory activity in vivo, while being an agonist in activating three other PAR2-activated pathways (cAMP, ERK, Rho) in human cells. These findings highlight opportunities to design drugs to block specific PAR2-linked signalling pathways in disease, without blocking beneficial PAR2 signalling in normal physiology, and to dissect PAR2-associated mechanisms of disease in vivo.

Gastrointestinal Endoscopy Competency Assessment Tool: development of a procedure-specific assessment tool for colonoscopy

BACKGROUND

Ensuring competence remains a seminal objective of endoscopy training programs, professional organizations, and accreditation bodies; however, no widely accepted measure of endoscopic competence currently exists.

OBJECTIVE

By using Delphi methodology, we aimed to develop and establish the content validity of the Gastrointestinal Endoscopy Competency Assessment Tool for colonoscopy.

DESIGN

An international panel of endoscopy experts rated potential checklist and global rating items for their importance as indicators of the competence of trainees learning to perform colonoscopy. After each round, responses were analyzed and sent back to the experts for further ratings until consensus was reached.

MAIN OUTCOME MEASUREMENTS

Consensus was defined a priori as ≥80% of experts, in a given round, scoring ≥4 of 5 on all remaining items.

RESULTS

Fifty-five experts agreed to be part of the Delphi panel: 43 gastroenterologists, 10 surgeons, and 2 endoscopy managers. Seventy-three checklist and 34 global rating items were generated through a systematic literature review and survey of committee members. An additional 2 checklist and 4 global rating items were added by Delphi panelists. Five rounds of surveys were completed before consensus was achieved, with response rates ranging from 67% to 100%. Seven global ratings and 19 checklist items reached consensus as good indicators of the competence of clinicians performing colonoscopy.

LIMITATIONS

Further validation required.

CONCLUSION

Delphi methodology allowed for the rigorous development and content validation of a new measure of endoscopic competence, reflective of practice across institutions. Although further evaluation is required, it is a promising step toward the objective assessment of competency for use in colonoscopy training, practice, and research.

Hypogammaglobulinemia in pediatric systemic lupus erythematosus

OBJECTIVE

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease typically associated with elevated serum immunoglobulin G (IgG). Hypogammaglobulinemia in SLE patients has been attributed to immunosuppressive treatment or a transient effect associated with nephrotic syndrome. We retrospectively reviewed pediatric SLE patients from a single institution to identify patients with hypogammaglobulinemia and risk factors for hypogammaglobulinemia.

METHODS

A total of 116 pediatric SLE cases from 1997 to 2011 were reviewed and patients with hypogammaglobulinemia (IgG < 500 mg/dl) were identified. The two cohorts were evaluated for association with age, sex, presence of lupus nephritis at SLE diagnosis, disease activity at diagnosis, initial IgG level, and drug treatment.

RESULTS

Eighty-six patients were included in our study, with a median age of 15 years and a median follow-up of 39.5 months. Seven percent (six of 86) of patients had hypogammaglobulinemia with a median onset of 27 months (0-72 months) after SLE diagnosis. Significant associations were noted for white race (p value 0.029), male sex (p value 0.009), and the presence of lupus nephritis at SLE diagnosis (p value 0.004). Use of immunosuppressive treatment did not show a statistical association with hypogammaglobulinemia, although two of the patients with hypogammaglobulinemia did receive rituximab. Most patients with hypogammaglobulinemia received intravenous immunoglobulin (IVIG) replacement therapy because of infections and/or concern for infection.

CONCLUSION

Measurement of immunoglobulin levels during treatment in SLE could help identify patients with hypogammaglobulinemia who might require more aggressive follow-up to monitor for increased risk of infection and need for IVIG treatment. A prospective study is needed to validate associated risk factors identified in this study.

Molecular characterization of the receptor binding structure-activity relationships of influenza B virus hemagglutinin

Selectivity of α2,6-linked human-like receptors by B hemagglutinin (HA) is yet to be fully understood. This study integrates binding data with structure-recognition models to examine the impact of regional-specific sequence variations within the receptor-binding pocket on selectivity and structure activity relationships (SAR). The receptor-binding selectivity of influenza B HAs corresponding to either B/Victoria/2/1987 or the B/Yamagata/16/88 lineages was examined using surface plasmon resonance, solid-phase ELISA and gel-capture assays. Our SAR data showed that the presence of asialyl sugar units is the main determinant of receptor preference of α2,6 versus α2,3 receptor binding. Changes to the type of sialyl-glycan linkage present on receptors exhibit only a minor effect upon binding affinity. Homology-based structural models revealed that structural properties within the HA pocket, such as a glyco-conjugate at Asn194 on the 190-helix, sterically interfere with binding to avian receptor analogs by blocking the exit path of the asialyl sugars. Similarly, naturally occurring substitutions in the C-terminal region of the 190-helix and near the N-terminal end of the 140-loop narrows the horizontal borders of the binding pocket, which restricts access of the avian receptor analog LSTa. This study helps bridge the gap between ligand structure and receptor recognition for influenza B HA; and provides a consensus SAR model for the binding of human and avian receptor analogs to influenza B HA.

Malignant melanoma in 63 dogs (2001-2011): the effect of carboplatin chemotherapy on survival

AIMS

The aim of the study was to compare the effect of carboplatin chemotherapy on the survival of canine patients diagnosed with malignant melanoma after loco-regional control or as a sole therapy.

METHODS

A retrospective study of 63 dogs with oral, digital or cutaneous malignant melanoma treated with surgery and/or chemotherapy was undertaken. Dogs were grouped based on the anatomical site of melanoma development. For oral melanoma, dogs were subclassified into two groups: loco-regional control and gross disease. All patients in the digital and cutaneous groups had achieved loco-regional control with surgery. Comparisons between survival data for each group at each anatomical site were then made. Within the loco-regional control groups survival time was compared between those treated with and without chemotherapy post surgery. For the oral melanoma patients with gross disease survival was compared between those treated with chemotherapy and palliative therapy. The toxicity of carboplatin chemotherapy was evaluated overall.

RESULTS

The overall median survival times for patients with oral, digital and cutaneous melanoma were 389, 1,350 days and not reached (with a median follow-up of 776 days) respectively. Median survival time was defined as "not reached" when less than 50% of the subjects died of the disease at the end of the follow-up period, or at the time they were lost to follow-up. The addition of chemotherapy to surgery did not confer a survival benefit in the loco-regional control setting when assessing survival for each anatomical site. For oral melanoma patients with gross disease there was no difference between survival of patients treated with chemotherapy and palliative intent therapy. There was however an improvement in survival in the three dogs that responded to chemotherapy (978 days; p=0.039) compared to the eight non-responders (147 days). On univariate and multivariate analysis, anatomic location was the only variable that was significantly related to survival (p=0.0002 and p=0.009, respectively).

CONCLUSIONS

The addition of chemotherapy to local treatments for canine melanoma at oral, digital and cutaneous sites did not lead to a significant increase in survival times. Carboplatin was well tolerated and appeared to have activity against oral melanoma in a subset of patients with gross disease that responded to treatment.

CLINICAL RELEVANCE

Carboplatin with piroxicam could be considered for patients with gross disease when more traditional therapies, such as surgery or radiation therapy, are declined or are not available. In the loco-regional control setting, prospective randomised blinded studies with matched control groups are required to determine if chemotherapy has a role in the treatment of these types of cancer.

Social status alters defeat-induced neural activation in Syrian hamsters

Although exposure to social stress leads to increased depression-like and anxiety-like behavior, some individuals are more vulnerable than others to these stress-induced changes in behavior. Prior social experience is one factor that can modulate how individuals respond to stressful events. In this study, we investigated whether experience-dependent resistance to the behavioral consequences of social defeat was associated with a specific pattern of neural activation. We paired weight-matched male Syrian hamsters in daily aggressive encounters for 2 weeks, during which they formed a stable dominance relationship. We also included control animals that were exposed to an empty cage each day for 2 weeks. Twenty-four hours after the final pairing or empty cage exposure, half of the subjects were socially defeated in 3, 5-min encounters, whereas the others were not socially defeated. Twenty-four hours after social defeat, animals were tested for conditioned defeat in a 5-min social interaction test with a non-aggressive intruder. We collected brains after social defeat and processed the tissue for c-Fos immunoreactivity. We found that dominants were more likely than subordinates to counter-attack the resident aggressor during social defeat, and they showed less submissive and defensive behavior at conditioned defeat testing compared with subordinates. Also, social status was associated with distinct patterns of defeat-induced neural activation in select brain regions, including the amygdala, prefrontal cortex, hypothalamus, and lateral septum. Our results indicate that social status is an important form of prior experience that predicts both initial coping style and the degree of resistance to social defeat. Further, the differences in defeat-induced neural activation suggest possible brain regions that may control resistance to conditioned defeat in dominant individuals.

Metastatic mast cell tumour in a dog presenting with spinal pain

The clinical, advanced imaging and surgical features of a case of canine extradural mast cell tumour are presented. This rare location has only been reported once before as a primary lesion, although the present case may be a metastatic lesion. Given the frequent occurrence and treatment of cutaneous mast cell tumours in dogs, the finding of spinal metastasis is an important reminder to consider metastatic neoplasia in cases of previously treated cancers presenting with spinal pain.

Aggressive encounters alter the activation of serotonergic neurons and the expression of 5-HT1A mRNA in the hamster dorsal raphe nucleus

Serotonergic (5-HT) neurons in the dorsal raphe nucleus (DRN) have been implicated in stress-induced changes in behavior. Previous research indicates that stressful stimuli activate 5-HT neurons in select subregions of the DRN. Uncontrollable stress is thought to sensitize 5-HT neurons in the DRN and allow for an exaggerated 5-HT response to future stimuli. In the current study, we tested the hypothesis that following aggressive encounters, losing male Syrian hamsters would exhibit increased c-Fos immunoreactivity in 5-HT DRN neurons compared to winners or controls. In addition, we tested the hypothesis that losers would have decreased 5-HT1A mRNA levels in the DRN compared to winners or controls. We found that a single 15-min aggressive encounter increased c-Fos expression in 5-HT and non-5-HT neurons in losers compared to winners and controls. The increased c-Fos expression in losers was restricted to ventral regions of the rostral DRN. We also found that four 5-min aggressive encounters reduced total 5-HT1A mRNA levels in the DRN in losers compared to winners and controls, and that differences in mRNA levels were not restricted to specific DRN subregions. These results suggest that social defeat activates neurons in select subregions of the DRN and reduces message for DRN 5-HT1A autoreceptors. Our results support the hypothesis that social stress can activate 5-HT neurons in the DRN, reduce 5-HT1A autoreceptor-mediated inhibition, and lead to hyperactivity of 5-HT neurons.

Referring patients to nurses: outcomes and evaluation of a nurse flexible sigmoidoscopy training program for colorectal cancer screening

Colorectal cancer is a significant health burden. Several screening options exist that can detect colorectal cancer at an early stage, leading to a more favourable prognosis. However, despite years of knowledge on best practice, screening rates are still very low in Canada, particularly in Ontario. The present paper reports on efforts to increase the flexible sigmoidoscopy screening capacity in Ontario by training nurses to perform this traditionally physician-performed procedure. Drawing on American, British and local experience, a professional regulatory framework was established, and training curriculum and assessment criteria were developed. Training was initiated at Princess Margaret Hospital and Sunnybrook and Women's College Health Sciences Centre in Toronto, Ontario. (During the study, Sunnybrook and Women's College Health Sciences Centre was deamalgamated into two separate hospitals: Women's College Hospital and Sunnybrook Health Sciences Centre.) Six registered nurses participated in didactic, simulator and practical training. These nurses performed a total of 77 procedures in patients, 23 of whom had polyps detected and biopsied. Eight patients were advised to undergo colonoscopy because they had one or more neoplastic polyps. To date, six of these eight patients have undergone colonoscopy, one patient has moved out of the province and another patient is awaiting the procedure. Classifying the six patients according to the most advanced polyp histology, one patient had a negative colonoscopy (no polyps found), one patient's polyps were hyperplastic, one had a tubular adenoma, two had advanced neoplasia (tubulovillous adenomas) and one had adenocarcinoma. All these lesions were excised completely at colonoscopy. Overall, many difficulties were anticipated and addressed in the development of the training program; ultimately, the project was affected most directly by challenges in encouraging family physicians to refer patients to the program. As health human resource strategies continue to evolve, it is believed that lessons learned from experience make an important contribution to the knowledge of how nontraditional health services can be organized and delivered.

Novel structural determinants of single-channel conductance in nicotinic acetylcholine and 5-hydroxytryptamine type-3 receptors

Nicotinic ACh (acetylcholine) and 5-HT3 (5-hydroxytryptamine type-3) receptors are cation-selective ion channels of the Cys-loop transmitter-gated ion channel superfamily. Numerous lines of evidence indicate that the channel lining domain of such receptors is formed by the alpha-helical M2 domain (second transmembrane domain) contributed by each of five subunits present within the receptor complex. Specific amino acid residues within the M2 domain have accordingly been demonstrated to influence both single-channel conductance (gamma) and ion selectivity. However, it is now clear from work performed on the homomeric 5-HT3A receptor, heteromeric 5-HT3A/5-HT3B receptor and 5-HT3A/5-HT3B receptor subunit chimaeric constructs that an additional major determinant of gamma resides within a cytoplasmic domain of the receptor termed the MA-stretch (membrane-associated stretch). The MA-stretch, within the M3-M4 loop, is not traditionally thought to be implicated in ion permeation and selection. Here, we describe how such observations extend to a representative neuronal nicotinic ACh receptor composed of alpha4 and beta2 subunits and, by inference, probably other members of the Cys-loop family. In addition, we will attempt to interpret our results within the context of a recently developed atomic scale model of the nicotinic ACh receptor of Torpedo marmorata (marbled electric ray).

Clinical recommendations for the use of recombinant human erythropoietin in patients with hepatitis C virus being treated with ribavirin

Today, combination antiviral therapy with pegylated interferon-alpha and ribavirin (RBV) allows many patients infected with hepatitis C virus (HCV) to achieve a sustained virological response, which is equivalent to cure. Data also support the clinical benefit of combination antiviral therapy in patients coinfected with HCV and HIV, and in patients who have received a liver transplant. Antiviral therapy with pegylated interferon-alpha and RBV is, however, associated with a high incidence and significant magnitude of anemia. This anemia may have several mechanisms, including bone marrow suppression and hemolysis. In addition, patients coinfected with HIV may have both pre-existing and RBV-associated anemia. Management of anemia in patients with HCV through RBV dose reduction or treatment discontinuation may compromise the effectiveness of treatment, because studies have demonstrated that treatment adherence or maintenance of antiviral therapy dose is an important predictor of sustained virological response. Anemia associated with combination antiviral therapy in patients with HCV is frequently associated with an inadequate or blunted endogenous erythropoietin response. Accumulating evidence now supports the use of recombinant human erythropoietin (rHuEpo) to manage anemia in these patients, with the objective of maintaining the RBV dose, but clinical standards are lacking. The present article reviews the data relevant to the use of rHuEpo in this patient population and proposes a set of clinical practice standards to assist clinicians in selecting patients for rHuEpo and in implementing rHuEpo therapy effectively.

N-methyl-D-aspartate receptors in the amygdala are necessary for the acquisition and expression of conditioned defeat

Here, we describe a biologically relevant model called conditioned defeat that is used to examine behavioral responses to social defeat in Syrian hamsters. In this model experimental animals that are normally aggressive experience social defeat and consequently display high levels of submissive/defensive behavior even in response to non-threatening conspecifics. N-methyl-D-aspartate (NMDA) receptors within the amygdala play an important role in conditioned fear; therefore, the purpose of this study was to examine whether NMDA receptors within the amygdala are necessary for the acquisition and expression of conditioned defeat. Specifically, the present study examined whether bilateral infusions of the NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid (AP5; 0.625, 1.25, 2.5, 5.0, 10.0 microg) into the amygdala would block the acquisition of conditioned defeat. Subsequently, we examined whether bilateral infusions of AP5 (0.625, 1.25, 2.5, 5.0 microg) into the amygdala prior to testing would block the expression of conditioned defeat. Infusions of AP5 into the amygdala immediately before the initial social defeat significantly reduced submissive/defensive behavior when hamsters were tested the following day with a non-aggressive intruder. Similarly, infusions of AP5 into the amygdala immediately before exposure to a non-aggressive intruder significantly attenuated the display of submissive/defensive behavior. These data demonstrate that NMDA receptors are necessary for both the acquisition and expression of conditioned defeat. We believe that conditioned defeat is a unique and valuable animal model with which to investigate the neurobiology of fear-related changes in social behavior.

Clinical pharmacology consultations: consultation requests may be misleading -- an organized approach to drug-induced hepatitis

The present case report describes a consultation with the Clinical Pharmacology Consultation Service at the Sunnybrook & Women's College Health Sciences Centre, Toronto, Ontario, for drug-induced hepatitis in a patient with multiple drug exposures. The original question to be addressed was whether dalteparin was responsible for an acute rise in liver transaminases. The approach involved establishing a best possible diagnosis of the adverse event, obtaining a comprehensive history of drug exposure and evaluating the possible contributory role of alternate etiologies supported by a literature search. On balance, based on temporal relationships and previous case reports, ranitidine was considered to be the most likely causal agent. The initial consultation request was to investigate the likelihood that daltaperin caused hepatitis; however, a systematic and comprehensive approach led to the conclusion that it was more likely to be ranitidine-induced hepatitis.

Lower gastrointestinal bleeding and ischemic colitis

OBJECTIVE

To compare the incidence and clinical characteristics of lower gastrointestinal (LGI) bleeding due to ischemic colitis with those with LGI bleeding of other causes.

METHODS

A chart review was performed of patients admitted with LGI bleeding to Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, between July 1, 1997 and January 31, 2000.

RESULTS

Of 124 patients with LGI bleeding, 24 cases were due to ischemic colitis, 62 to diverticulosis, 11 to inflammatory bowel disease (IBD) and 27 to all other causes ('others'). The average ages of patients in each group were 66.5, 76.5, 40.5 and 77.5 years, respectively. Patients with ischemic colitis were statistically younger than those with diverticular bleeding and 'others'. Patients with IBD were younger than those in the other three groups. The only statistical difference for vascular disease risks was hypertension, because of its absence from the IBD group. Three patients with ischemic colitis underwent blood transfusions, while 23 with diverticulosis, 15 'others' and none with IBD received blood. Three patients with ischemic colitis and one patient from the 'others' group died. More women (75) than men (49) had LGI bleeding - in total and within each subgroup. Of women with LGI bleeding, many more with ischemic colitis (44.4%) than with diverticulosis (3.0%), IBD (0%) or 'others' (5.6%) were taking estrogen.

CONCLUSIONS

Ischemic colitis was the second most common cause of LGI bleeding. LGI bleeding from all causes was more common in women than in men. Many more women in the ischemic colitis group than in the other groups were using estrogen therapy.

The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore-forming mechanism

Maculatin 1.1 is an antimicrobial peptide isolated from the Australian tree frog Litoria genimaculata that adopts an amphipathic, alpha-helical structure in solution. Its orientation and conformation when incorporated to pre-formed DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) and DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) vesicles was determined using polarised Fourier transform infrared-attenuated total reflection infrared and deuterium exchange experiments. For DMPG membranes, our results show insertion of 70% of the maculatin 1.1 molecules, with an angle of insertion of approximately 35 degrees to the membrane normal and with a predominant alpha-helical structure. These results suggest that maculatin 1.1 acts through a pore-forming mechanism to lyse bacterial membranes. A similar degree of insertion in DMPG (65%) and alpha-helical structure was observed for a biologically inactive, less amphipathic maculatin 1.1 analogue, P15A, although the helix tilt was found to be greater (46 degrees) than for maculatin 1.1. Similar experiments performed using DMPC liposomes showed poor insertion, less than 5%, for both maculatin 1.1 and its analogue. In addition, the shape of the amide I band in these samples is consistent with alpha-helix, beta-structure and disordered structures being present in similar proportion. These results clearly show that maculatin 1.1 inserts preferentially in negatively charged membranes (DMPG) which mimic the negatively charged membrane of Gram-positive bacteria. We attribute the high percentage of insertion of the biologically inactive analogue in DMPG to the fact that its concentration on the membrane surface in our experiments is likely to be much higher than that found in physiological conditions.

Identification of ARAP3, a novel PI3K effector regulating both Arf and Rho GTPases, by selective capture on phosphoinositide affinity matrices

We show that matrices carrying the tethered homologs of natural phosphoinositides can be used to capture and display multiple phosphoinositide binding proteins in cell and tissue extracts. We present the mass spectrometric identification of over 20 proteins isolated by this method, mostly from leukocyte extracts: they include known and novel proteins with established phosphoinositide binding domains and also known proteins with surprising and unusual phosphoinositide binding properties. One of the novel PtdIns(3,4,5)P3 binding proteins, ARAP3, has an unusual domain structure, including five predicted PH domains. We show that it is a specific PtdIns(3,4,5)P3/PtdIns(3,4)P2-stimulated Arf6 GAP both in vitro and in vivo, and both its Arf GAP and Rho GAP domains cooperate in mediating PI3K-dependent rearrangements in the cell cytoskeleton and cell shape.

Effects of antibody concentration on the separation of human natural killer cells in a commercial immunomagnetic separation system

BACKGROUND

The magnetic separation of a cell population based on cell surface markers is a critical step in many biological and clinical laboratories. In this study, the effect of antibody concentration on the separation of human natural killer cells in a commercial, immunomagnetic cell separation system was investigated.

METHODS

Specifically, the degree of saturation of antibody binding sites using a two-step antibody sandwich was quantified. The quantification of the first step, a primary anti-CD56-PE antibody, was achieved through fluorescence intensity measurements using a flow cytometer. The quantification of the second step, an anti-PE-microbeads antibody reagent, was achieved through magnetophoretic mobility measurements using cell tracking velocimetry.

RESULTS

From the results of these studies, two different labeling protocols were used to separate CD56+ cells from human, peripheral blood by a Miltenyi Biotech MiniMACS cell separation system. The first of these two labeling protocols was based on company recommendations, whereas the second was based on the results of the saturation studies. The results from these studies demonstrate that the magnetophoretic mobility is a function of both primary and secondary antibody concentrations and that mobility does have an effect on the performance of the separation system.

CONCLUSIONS

As the mobility increased due to an increase in bound antibodies, the positive cells were almost completely eliminated from the negative eluent. However, with an increase in bound antibodies, and thus mobility, the total amount of positive cells recovered decreases. It is speculated that these cells are irreversibly retained in the column. These results demonstrate the complexity of immunomagnetic cell separation and the need to further optimize the cell separation process.

FENS-1 and DFCP1 are FYVE domain-containing proteins with distinct functions in the endosomal and Golgi compartments

FENS-1 and DFCP1 are recently discovered proteins containing one or two FYVE-domains respectively. We show that the FYVE domains in these proteins can bind PtdIns3P in vitro with high specificity over other phosphoinositides. Exogenously expressed FENS-1 localises to early endosomes: this localisation requires an intact FYVE domain and is sensitive to wortmannin inhibition. The isolated FYVE domain of FENS-1 also localises to endosomes. These results are consistent with current models of FYVE-domain function in this cellular compartment. By contrast, exogenously expressed DFCP1 displays a predominantly Golgi, endoplasmic reticulum (ER) and vesicular distribution with little or no overlap with FENS-1 or other endosomal markers. Overexpression of DFCP1 was found to cause dispersal of the Golgi compartment defined by giantin and gpp130-staining. Disruption of the FYVE domains of DFCP1 causes a shift to more condensed and compact Golgi structures and overexpression of this mutant was found to confer significant protection to the Golgi against brefeldin-induced dispersal. These properties of DFCP1 are surprising, and suggest FYVE domain-localisation and function may not be exclusively endosomal.

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The biology of human natural killer-cell subsets

Human natural killer (NK) cells comprise approximately 15% of all circulating lymphocytes. Owing to their early production of cytokines and chemokines, and ability to lyse target cells without prior sensitization, NK cells are crucial components of the innate immune system. Human NK cells can be divided into two subsets based on their cell-surface density of CD56--CD56(bright) and CD56(dim)--each with distinct phenotypic properties. Now, there is ample evidence to suggest that these NK-cell subsets have unique functional attributes and, therefore, distinct roles in the human immune response. The CD56(dim) NK-cell subset is more naturally cytotoxic and expresses higher levels of Ig-like NK receptors and FCgamma receptor III (CD16) than the CD56(bright) NK-cell subset. By contrast, the CD56(bright) subset has the capacity to produce abundant cytokines following activation of monocytes, but has low natural cytotoxicity and is CD16(dim) or CD16(-). In addition, we will discuss other cell-surface receptors expressed differentially by human NK-cell subsets and the distinct functional properties of these subsets.

Fatal leukemia in interleukin-15 transgenic mice

The role of inflammation in the early genesis of certain malignancies has recently been appreciated. Interleukin (IL)-15, a proinflammatory cytokine and growth factor, is required for lymphocyte homeostasis. Intriguingly, the expression of IL-15 protein is tightly controlled by multiple posttranscriptional mechanisms, suggesting that inappropriate expression of IL-15 may be detrimental to the host. We recently engineered a transgenic mouse in which the normal posttranscriptional control of IL-15 is eliminated, thereby overexpressing the murine IL-15 protein. IL-15 transgenic mice have early expansions in NK and CD8+ T lymphocytes and later develop fatal lymphocytic leukemia with a T-NK phenotype. This article recapitulates the phenotype of these IL-15 transgenic mice and discusses the utility of this model as a tool to further our understanding of leukemogenesis.

Direct and sensitive detection of a human virus by rupture event scanning

We have developed a sensitive, economical method that directly detects viruses by making use of the interaction between type 1 herpes simplex virus (HSV1) and specific antibodies covalently attached to the oscillating surface of a quartz crystal microbalance (QCM). The virions were detached from the surface by monotonously increasing the amplitude of oscillation of the QCM, while using the QCM to sensitively detect the acoustic noise produced when the interactions were broken. We term this process rupture event scanning (REVS). The method is quantitative over at least six orders of magnitude, and its sensitivity approaches detection of a single virus particle.

PtdIns(3)P regulates the neutrophil oxidase complex by binding to the PX domain of p40(phox)

The production of reactive oxygen species (ROS) by neutrophils has a vital role in defence against a range of infectious agents, and is driven by the assembly of a multi-protein complex containing a minimal core of five proteins: the two membrane-bound subunits of cytochrome b(558) (gp91(phox) and p22(phox)) and three soluble factors (GTP-Rac, p47(phox) and p67(phox) (refs 1, 2). This minimal complex can reconstitute ROS formation in vitro in the presence of non-physiological amphiphiles such as SDS. p40(phox) has subsequently been discovered as a binding partner for p67(phox) (ref. 3), but its role in ROS formation is unclear. Phosphoinositide-3-OH kinases (PI(3)Ks) have been implicated in the intracellular signalling pathways coordinating ROS formation but through an unknown mechanism. We show that the addition of p40(phox) to the minimal core complex allows a lipid product of PI(3)Ks, phosphatidylinositol 3-phosphate (PtdIns(3)P), to stimulate specifically the formation of ROS. This effect was mediated by binding of PtdIns(3)P to the PX domain of p40(phox). These results offer new insights into the roles for PI(3)Ks and p40(phox) in ROS formation and define a cellular ligand for the orphan PX domain.

Human natural killer cells: a unique innate immunoregulatory role for the CD56(bright) subset

During the innate immune response to infection, monocyte-derived cytokines (monokines), stimulate natural killer (NK) cells to produce immunoregulatory cytokines that are important to the host's early defense. Human NK cell subsets can be distinguished by CD56 surface density expression (ie, CD56(bright) and CD56(dim)). In this report, it is shown that CD56(bright) NK cells produce significantly greater levels of interferon-gamma, tumor necrosis factor-beta, granulocyte macrophage-colony-stimulating factor, IL-10, and IL-13 protein in response to monokine stimulation than do CD56(dim) NK cells, which produce negligible amounts of these cytokines. Further, qualitative differences in CD56(bright) NK-derived cytokines are shown to be dependent on the specific monokines present. For example, the monokine IL-15 appears to be required for type 2 cytokine production by CD56(bright) NK cells. It is proposed that human CD56(bright) NK cells have a unique functional role in the innate immune response as the primary source of NK cell-derived immunoregulatory cytokines, regulated in part by differential monokine production.

Chemical force microscopy with active enzymes

The adhesion forces have been measured between an atomic force microscope tip derivatized with an active enzyme, shikimate kinase, and an ATP mimic immobilized on a gold surface. Experiments with competitive binding of other ligands in solution show that the observed adhesion forces arise predominantly from specific interactions between the immobilized enzyme and surface-bound adenine derivative. These experiments represent a step in the development of a screening methodology based upon chemical force microscopy.

The extent and nature of emergency nurse practitioner services in Scotland

Emergency Nurse Practitioners (ENPs) are being used in an increasing proportion of A&E departments across England and Wales. This paper reports the findings of a postal survey sent to all (94) A&E departments in Scotland including the smaller GP run units. The aim of the study was to document the extent and nature of ENP services in Scotland. Nurses were found to be practising as ENPs in 47% of Scottish A&E departments. The majority (70%) of nurses practising as ENPs had been educated for the role on courses for ENPs. Nurses working as ENPs were being paid at all grades ranging from the lowest grade for a staff nurse (D-grade) through to H-grade. ENPs are practising in all types of A&E department. Most ENPs have been formally trained for the role, however huge variation exists in educational preparation and in remuneration for this expanded nursing role.

Kinetically selective binding of single stranded RNA over DNA by a pyrrolidine-amide oligonucleotide mimic (POM)

Replacing the sugar-phosphodiester backbone of nucleic acids with a pyrrolidine-amide backbone results in an oligonucleotide mimic POM 1 which binds with high affinity and specificity to complementary DNA and RNA. Unlike other modified oligonucleotides, POM binds much more rapidly to single stranded RNA than DNA.

Interleukin-1beta costimulates interferon-gamma production by human natural killer cells

Natural killer (NK) cells are an early source of immunoregulatory cytokines during the innate immune response to viruses, bacteria, and parasites. NK cells provide requisite IFN-gamma to monocytes for the elimination of obligate intracellular pathogens. IL-1beta is a pro-inflammatory cytokine produced by monocytes (i.e. a monokine) during the early immune response to infection, but its role in promoting human NK cell IFN-gamma production is unknown. The current study examines the ability of the monokine IL-1beta, plus IL-12, to costimulate IFN-gamma production by resting CD56(bright) and CD56(dim) human NK cell subsets. CD56(bright) NK cells stimulated with IL-1beta plus IL-12 produced abundant IFN-gamma protein, while little IFN-gamma was produced in identical cultures of CD56(dim) cells. In addition, upon activation with IL-1beta, CD56(bright) NK cells exhibited considerably greater phosphorylation of extracellular signal-regulated kinases p42/44 as compared to CD56(dim) NK cells. Quantitative PCR analysis showed brisk induction of IFN-gamma gene expression following costimulation with IL-1beta plus IL-12 in CD56(bright) NK cells, but intracellular flow cytometry revealed that only a fraction (42+/-2.3%) of CD56(bright) NK cells account for this high IFN-gamma production. These data suggest that the monokine IL-1beta is a potent costimulus of IFN-gamma production by a subset of NK cells following infectious insult.

A case of chronic pancreatic insufficiency due to valproic acid in a child

A 14-year-old child treated with valproic acid over several years for a seizure disorder developed abdominal pain with radiological evidence of acute pancreatitis. The association with valproic acid was not recognized, and the child continued to take the drug. The patient eventually developed steatorrhea and weight loss that improved with pancreatic enzyme replacement. Radiological evaluation showed an atrophic pancreas. Without evidence of other etiological factors, valproic acid by itself appeared to be the cause of chronic pancreatitis with exocrine pancreatic insufficiency in this patient.

Deliberate self-harm in children: the nurse's therapeutic style

This article examines child health nursing skills in the management of deliberate self-harm in children and young people. In order for education to be effective (i.e. so that it changes practice) it must address the belief systems of the practitioner. It is suggested that such belief systems are embedded in collectively held tribal stories. The more challenging the patient's behaviour, the more powerful the influence of the tribal narrative--possibly as a defensive strategy. The authors outline strategies aimed at increasing the range and depth of the therapeutic response to episodes of self-harm, and outline nursing interventions in the management of self-harming children.

Binding of vancomycin group antibiotics to D-alanine and D-lactate presenting self-assembled monolayers

Peptides terminating in -Lys-D-Ala-D-Ala, -Lys-D-Ala-L-Ala and -Lys-D-Ala-D-Lactate were covalently coupled via an N-terminal aminohexanoic acid linker to a self-assembled monolayer of HS(CH2)15CO2H on a thin gold film. Binding of the glycopeptide antibiotics vancomycin and chloroeremomycin to these surfaces was then measured using a surface plasmon resonance biosensor. Both antibiotics bound with micromolar affinity to the D-Ala-terminating surface and with millimolar affinity to the D-Lactate-terminating surface. Increasing density of these covalently attached peptides on the surface had no effect on the resultant affinities of either antibiotic for the surface. In contrast, when the lipid-anchored peptide N-alpha-docosanoyl-epsilon-acetyl-Lys-D-Ala-D-Ala was inserted into a supported lipid monolayer, the affinity of the strongly dimerizing antibiotic chloroeremomycin for the surface showed a dependence on ligand density. This was not the case with the weakly dimerizing antibiotic vancomycin. The lipid monolayer surface, which is a more realistic model of the surface of a bacterium, was thus better suited for the study of the cooperative binding interactions that occur between dimeric glycopeptide antibiotics and surface-bound ligands.

National athletic trainers' association position statement: lightning safety for athletics and recreation

OBJECTIVE

To educate athletic trainers and others about the dangers of lightning, provide lightning-safety guidelines, define safe structures and locations, and advocate prehospital care for lightning-strike victims.

BACKGROUND

Lightning may be the most frequently encountered severe-storm hazard endangering physically active people each year. Millions of lightning flashes strike the ground annually in the United States, causing nearly 100 deaths and 400 injuries. Three quarters of all lightning casualties occur between May and September, and nearly four fifths occur between 10:00 AM and 7:00 PM, which coincides with the hours for most athletic or recreational activities. Additionally, lightning casualties from sports and recreational activities have risen alarmingly in recent decades.

RECOMMENDATIONS

The National Athletic Trainers' Association recommends a proactive approach to lightning safety, including the implementation of a lightning-safety policy that identifies safe locations for shelter from the lightning hazard. Further components of this policy are monitoring local weather forecasts, designating a weather watcher, and establishing a chain of command. Additionally, a flash-to-bang count of 30 seconds or more should be used as a minimal determinant of when to suspend activities. Waiting 30 minutes or longer after the last flash of lightning or sound of thunder is recommended before athletic or recreational activities are resumed. Lightning- safety strategies include avoiding shelter under trees, avoiding open fields and spaces, and suspending the use of land-line telephones during thunderstorms. Also outlined in this document are the prehospital care guidelines for triaging and treating lightning-strike victims. It is important to evaluate victims quickly for apnea, asystole, hypothermia, shock, fractures, and burns. Cardiopulmonary resuscitation is effective in resuscitating pulseless victims of lightning strike. Maintenance of cardiopulmonary resuscitation and first-aid certification should be required of all persons involved in sports and recreational activities.

Coadministration of interleukin-18 and interleukin-12 induces a fatal inflammatory response in mice: critical role of natural killer cell interferon-gamma production and STAT-mediated signal transduction

The administration of therapeutic doses of recombinant cytokines to patients with malignant disease can be complicated by systemic toxicities, which in their most severe form may present as a systemic inflammatory response. The combination of interleukin (IL)-18 and IL-12 has synergistic antitumor activity in vivo yet has been associated with significant toxicity. The effects of IL-18 plus IL-12 were examined in a murine model, and it was found that the daily, simultaneous administration of IL-18 and IL-12 resulted in systemic inflammation and 100% mortality within 4 to 8 days depending on the strain employed. Mice treated with IL-18 plus IL-12 exhibited unique pathologic findings as well as elevated serum levels of proinflammatory cytokines and acute-phase reactants. The actions of tumor necrosis factor-alpha did not contribute to the observed toxicity, nor did T or B cells. However, toxicity and death from treatment with IL-18 plus IL-12 could be completely abrogated by elimination of natural killer (NK) cells or macrophages. Subsequent studies in genetically altered mice revealed that NK-cell interferon-gamma mediated the fatal toxicity via the signal transducer and activator of transcription pathway of signal transduction. These data may provide insights into methods of ameliorating cytokine-induced shock in humans. (Blood. 2000;96:1465-1473)