Gefitinib modulates the function of multiple ATP-binding cassette transporters in vivo

The 4-anilinoquinazoline (4-AQ) derivative gefitinib (Iressa) is an oral epidermal growth factor receptor tyrosine kinase inhibitor. Oral administration of 4-AQ molecules, such as gefitinib, inhibits ATP-binding cassette (ABC) transporter-mediated drug efflux and strongly increases the apparent bioavailability of coadministered drug molecules that are transporter substrates. Based on in vitro studies investigating 4-AQ interactions with several transporters, these effects have primarily been attributed to the inhibition of breast cancer resistance protein (BCRP; ABCG2). Although 4-AQ shows in vitro inhibition of P-glycoprotein [multidrug resistance protein (MDR1); ABCB1], the in vivo effect on this and other transporters is not known. In our studies, pretreatment of Abcg2(-/-) and Mdr1(a/b)(-/-) mice with gefitinib increased oral absorption and decreased systemic clearance of topotecan, a model substrate, indicating that additional transporters were inhibited. These results were extended to human orthologues using engineered cell lines to show that gefitinib inhibited the efflux of BCRP and MDR1 substrates and restored vincristine sensitivity in MDR1-expressing cells. Although gefitinib inhibited BCRP more potently than MDR1 (10-fold), the inhibition of both transporters occurred at clinically relevant concentrations (e.g., 1-5 micromol/L). These studies illustrate the broad implications for the therapeutic combination of gefitinib or other 4-AQ molecules with agents that are BCRP and MDR1 substrates. 4-AQ molecules may offer a means to increase the low and variable oral drug absorption of transporter substrates while decreasing interpatient variability and reversing tumor drug resistance.

Integrating complementary and alternative medicine into academic medical centers: experience and perceptions of nine leading centers in North America

Background

Patients across North America are using complementary and alternative medicine (CAM) with increasing frequency as part of their management of many different health conditions. The objective of this study was to develop a guide for academic health sciences centers that may wish to consider starting an integrative medicine program.

Methods

We queried North American leaders in the field of integrative medicine to identify initial sites. Key stakeholders at each of the initial sites visited were then asked to identify additional potential study sites (snowball sampling), until no new sites were identified. We conducted structured interviews to identify critical factors associated with success and failure in each of four domains: research, education, clinical care, and administration. During the interviews, field notes were recorded independently by at least two investigators. Team meetings were held after each visit to reach consensus on the information recorded and to ensure that it was as complete as possible. Content analysis techniques were used to identify key themes that emerged from the field notes.

Results

We identified ten leading North American integrative medical centers, and visited nine during 2002–2003. The centers visited suggested that the initiation of an integrative medicine program requires a significant initial outlay of funding and a motivated "champion". The centers had important information to share regarding credentialing, medico-legal issues and billing for clinical programs; identifying researchers and research projects for a successful research program; and strategies for implementing flexible educational initiatives and establishing a functional administrative structure.

Conclusion

Important lessons can be learned from academic integrative programs already in existence. Such initiatives are timely and feasible in a variety of different ways and in a variety of settings.

Mrp4 confers resistance to topotecan and protects the brain from chemotherapy

The role of the multidrug resistance protein MRP4/ABCC4 in vivo remains undefined. To explore this role, we generated Mrp4-deficient mice. Unexpectedly, these mice showed enhanced accumulation of the anticancer agent topotecan in brain tissue and cerebrospinal fluid (CSF). Further studies demonstrated that topotecan was an Mrp4 substrate and that cells overexpressing Mrp4 were resistant to its cytotoxic effects. We then used new antibodies to discover that Mrp4 is unique among the anionic ATP-dependent transporters in its dual localization at the basolateral membrane of the choroid plexus epithelium and in the apical membrane of the endothelial cells of the brain capillaries. Microdialysis sampling of ventricular CSF demonstrated that localization of Mrp4 at the choroid epithelium is integral to its function in limiting drug penetration into the CSF. The topotecan resistance of cells overexpressing Mrp4 and the polarized expression of Mrp4 in the choroid plexus and brain capillary endothelial cells indicate that Mrp4 has a dual role in protecting the brain from cytotoxins and suggest that the therapeutic efficacy of central nervous system-directed drugs that are Mrp4 substrates may be improved by developing Mrp4 inhibitors.

Determination of plasma topotecan and its metabolite N-desmethyl topotecan as both lactone and total form by reversed-phase liquid chromatography with fluorescence detection

Topotecan (TPT) undergoes hepatic N-demethylation forming N-desmethyl topotecan (NDS). To evaluate the effect of drug-drug interactions on NDS disposition in children receiving TPT we developed and validated a sensitive and specific HPLC-fluorescence detection method for lactone and total (lactone plus carboxylate) TPT and NDS. Deproteinized plasma is vortexed, centrifuged, and the methanolic extract diluted with water for the lactone form of NDS and TPT or diluted with 1.5% phosphoric acid for NDS and TPT total. A 100 microL sample is injected onto a Varian ChromGuard RP column attached to an Agilent SB-C(18) reversed-phase analytical column held at 50 degrees C. The mobile phase (flow-rate, 0.8 mL/min) consists of methanol-aqueous buffer (27:73, v/v) (75 mM potassium phosphate and 0.2% triethylamine, pH 6.5). TPT and NDS were detected with excitation and emission wavelengths set at 376 and 530 nm, respectively. The standard curves for both forms of TPT ranged from 0.25 to 80 ng/mL, and for NDS ranged from 0.10 to 8.0 ng/mL. Within-day and between-day precision (% RSD) was </=4% for TPT and </=6.2% for NDS, respectively. Within-day and between-day percentage error ranged from 1.4 to 6.3% and from 1.4 to 2.4% for TPT, and from 1.6 to 3.1% and from 0.0 to 3.7% for NDS, respectively. No significant on-column conversion from TPT or NDS lactone to carboxylate was observed. With one method we can measure lactone and total TPT and NDS with adequate sensitivity to allow for evaluation of the disposition of these compounds in children receiving TPT.

A pilot study to determine the effectiveness of garlic oil capsules in the treatment of dyspeptic patients with Helicobacter pylori

BACKGROUND

Resistance of Helicobacter pylori to clarithromycin and metronidazole is now found worldwide. Steam-distilled garlic oil has in vitro activity against H. pylori and may be a useful alternative treatment strategy.

MATERIALS AND METHODS

In this pilot study dyspeptic patients with positive serology for H. pylori confirmed by 13C urea breath test (UBT), at 0 and 2 weeks, were enrolled. Treatment consisted of one 4 mg garlic oil capsule with a meal four times per day for 14 days. H. pylori eradication was defined as a negative UBT at both follow-up appointments. Suppression was defined as a 50% fall in 13C excess between baseline and follow-up 1.

RESULTS

Five patients completed the study. There was no evidence of either eradication or suppression of H. pylori or symptom improvement whilst taking garlic oil.

CONCLUSION

These negative results show that, within the gastric milieu, garlic oil at this dose does not inhibit H. pylori. A higher dose administered for a longer time-period may be effective. Antibiotics are usually combined with a proton-pump inhibitor or bismuth salt, as the only antibiotic with any in vivo activity against H. pylori in monotherapy is clarithromycin. A proton pump inhibitor raises gastric pH and, by increasing bacterial division, may increase the in vivo activity of garlic oil. This may be worth pursuing in a future trial.

Neuronal nitric oxide synthase (NOS) regulates leukocyte-endothelial cell interactions in endothelial NOS deficient mice

1. The present study was designed to examine the possible role of neuronal nitric oxide synthase (nNOS) in regulation of leukocyte - endothelial cell interactions in the absence of endothelial nitric oxide synthase (eNOS), using intravital microscopy of the cremasteric microcirculation of eNOS(-/-) mice. 2. Baseline leukocyte rolling and adhesion revealed no differences between wild-type and eNOS(-/-) mice in either the cremasteric or intestinal microcirculations. 3. Superfusion with L-NAME (100 microM) caused a progressive and significant increase in leukocyte adhesion in both wild-type and eNOS(-/-) mice, without detecting differences between the two strains of mice. 4. Superfusion with 7-nitroindazole (100 microM), a selective inhibitor of nNOS, had no effect on leukocyte adhesion in wild-type animals. However, it increased leukocyte adhesion significantly in eNOS(-/-) mice, which was reversed by systemic L-arginine pre-administration. 5. Stimulation of the microvasculature with H(2)O(2) (100 microM) induced a transient elevation in leukocyte rolling in wild-type mice. Conversely, the effect persisted during the entire 60 min of experimental protocol in eNOS(-/-) mice either with or without 7-nitroindazole. 6. Semi-quantitative analysis by RT - PCR of the mRNA for nNOS levels in eNOS(-/-) and wild-type animals, showed increased expression of nNOS in both brain and skeletal muscle of eNOS(-/-) mice. 7. In conclusion, we have demonstrated that leukocyte-endothelial cell interactions are predominantly modulated by eNOS isoform in postcapillary venules of normal mice, whereas nNOS appears to assume the same role in eNOS(-/-) mice. Interestingly, unlike eNOS there was insufficient NO produced by nNOS to overcome leukocyte recruitment elicited by oxidative stress, suggesting that nNOS cannot completely compensate for eNOS.

Predictors of patient response to antibiotic therapy for the chronic prostatitis/chronic pelvic pain syndrome: a prospective multicenter clinical trial

PURPOSE

To our knowledge antibiotics are the most popular choice of therapy for all categories of the chronic prostatitis/chronic pelvic pain syndrome. We determine if culture, leukocyte and/or antibody status of prostate specific specimens predicts patient response to antibiotic therapy.

MATERIALS AND METHODS

Patients clinically diagnosed with the chronic prostatitis/chronic pelvic pain syndrome according to the National Institutes of Health (NIH) definition had a lower urinary tract evaluation that included standard microscopy and culture of prostate specific specimens, and determination of the ratio of voided bladder 3 and voided bladder 2 antibody levels against a panel of identified prostate pathogens (enzyme linked immunosorbent assay methodology). Symptom evaluation consisted of the NIH chronic prostatitis symptom index (derived) pain scale 0 to 21, symptom severity index scale 0 to 100, symptom frequency questionnaire scale 0 to 50 and quality of life scale 0 to 6. Patients were stratified according to microscopy, culture and immune status, were treated with 12 weeks of ofloxacin, and were assessed at 4, 12 and 24 weeks with symptom scores as well as global assessments.

RESULTS

Based on leukocyte and culture results, 102 evaluable patients were stratified into categories II (14%), IIIA (48%) and IIIB (38%) of the chronic prostatitis/chronic pelvic pain syndrome. Of the cases 23% were categorized as antibody positive and 77% as antibody negative. Average age was 42 +/- 10 years and 92% of patients were white. Of the patients 57% believed that they had moderate to marked improvement. All categories of the chronic prostatitis/chronic pelvic pain syndrome and patients in whom antibody was positive or negative had significant improvement in the NIH chronic prostatitis symptom index, symptom severity index, symptom frequency questionnaire and quality of life scores compared with baseline (p <0.001). There was no significant difference in patient response to the stratification based on culture, leukocyte, that is categories II, IIIA and IIIB had same beneficial response, or antibody status.

CONCLUSIONS

Culture, leukocyte and antibody status of prostate specific specimens does not predict antibiotic response in patients with the chronic prostatitis/chronic pelvic pain syndrome. The perceived beneficial effect of antibiotics needs to be evaluated in a randomized placebo controlled trial.

Bonzo/CXCR6 expression defines type 1-polarized T-cell subsets with extralymphoid tissue homing potential

Chemokine receptor expression is finely controlled during T-cell development. We show that newly identified chemokine receptor Bonzo/CXCR6 is expressed by subsets of Th1 or T-cytotoxic 1 (Tc1) cells, but not by Th2 or Tc2 cells, establishing Bonzo as a differential marker of polarized type 1 T cells in vitro and in vivo. Priming of naive T cells by dendritic cells induces expression of Bonzo on T cells. IL-12 enhances this dendritic cell-dependent upregulation, while IL-4 inhibits it. In blood, 35-56% of Bonzo+ CD4 T cells are Th1 cells, and 60-65% of Bonzo+ CD8 T cells are Tc1 cells, while few Bonzo+ cells are type 2 T cells. Almost all Bonzo+ Tc1 cells contain preformed granzyme A and display cytotoxic effector phenotype. Most Bonzo+ T cells lack L-selectin and/or CCR7, homing receptors for lymphoid tissues. Instead, Bonzo+ T cells are dramatically enriched among T cells in tissue sites of inflammation, such as rheumatoid joints and inflamed livers. Bonzo may be important in trafficking of effector T cells that mediate type 1 inflammation, making it a potential target for therapeutic modulation of inflammatory diseases.

Pentosan polysulfate therapy for chronic nonbacterial prostatitis (chronic pelvic pain syndrome category IIIA): a prospective multicenter clinical trial

OBJECTIVES

Chronic nonbacterial prostatitis/chronic pelvic pain syndrome (CPPS) has clinical and perhaps etiologic characteristics similar to interstitial cystitis. Pentosan polysulfate sodium (PPS), an oral medication indicated for the treatment of interstitial cystitis, has shown moderate benefit in reducing chronic pelvic pain and voiding symptoms in patients with interstitial cystitis. We undertook a prospective open-label, multicenter Phase II pilot study to examine the potential efficacy of PPS in the treatment of CPPS in men, using outcome tools validated for CPPS in men.

METHODS

Patients with a diagnosis consistent with National Institutes of Health (NIH) CPPS category IIIA (inflammatory) were treated with PPS, 100 mg three times daily, for 6 months. The evaluation at baseline, 3 months, and 6 months consisted of the Symptom Severity Index, a Symptom Frequency Questionnaire, the NIH-Chronic Prostatitis Symptom Pain Index (NIH-CPSI), a quality-of-life assessment, and a subjective global assessment.

RESULTS

Thirty-two patients (mean age 45.5 +/- 11 years; duration of symptoms 9.2 +/- 12 years) were enrolled in five centers; 28 patients were available for evaluation. Seven patients experienced drug-related side effects, including hair loss (n = 2), headache (n = 2), mild nausea (n = 1), mild weight gain (n = 1), and skin flushing (n = 1). The decrease in frequency (Symptom Frequency Questionnaire 28.1 to 17.9), severity (Symptom Severity Index 53.6 to 36.3), and combined location/frequency/severity of pain (NIH-CPSI pain 14.5 to 9.2) symptom scores at 6 months compared with baseline was significant. The decrease was associated with a significant improvement in patients' quality of life (quality-of-life assessment 5.3 to 3.8). Forty-three percent of the patients had a greater than 50% improvement in the Symptom Frequency Questionnaire, Symptom Severity Index, and NIH-CPSI (rated as clinically significant improvement). At 6 months, mild, moderate, and marked improvement was noted (subjective global assessment) by 33%, 19%, and 15% of the patients, respectively.

CONCLUSIONS

PPS is well tolerated and appears to have efficacy in reducing the severity and frequency of general symptoms, reducing specific pain symptoms, and improving the quality of life in many male patients with CPPS. The results of this study justify the initiation of a randomized controlled trial comparing the safety and efficacy of PPS to placebo.

Exploring the new frontier: home care gets wired

The driving forces toward adoption of TeleCare into the non-acute care setting are more compelling than ever before. The dramatic increase in our elderly population, which provides an endless consumer base, availability of functional and affordable technologies, and a national mandate to control costs of health care are forcing even the most skeptical health care decisionmakers to accept TeleCare as a standard model of care. Add to this the most severe nursing shortage to date and the formula is complete.

Analysis of multivariables during porcine liver digestion to improve hepatocyte yield and viability for use in bioartificial liver support systems

In order to achieve optimal BALSS function, preparation of porcine hepatocytes with high yield, viability, and P450 activity is known to be important. To date hepatocyte yields have varied from 0.58 x 10(10) to 3.45 x 10(10) and viabilities from 75% to 95% within and between laboratories, even when using the same digestion methods and procedures, indicating that hepatocyte isolation during porcine liver digestion is not fully optimized. The aim of this work was to identify the critical parameters affecting cell recovery during porcine liver harvesting by investigating 21 variables involved in the process, including pig body and liver weight, different digestion times of perfusates, pH, a range of concentrations of sodium and chloride in EDTA, and collagenase perfusates. Univariate and multivariate analysis of a retrospective study (n = 23) revealed that low perfusate pH during the process of digestion had a positive effect on hepatocyte yield (p < 0.05), while high (relative) concentrations of sodium and chloride in the perfusates had significant negative effects on hepatocyte viability (both p < 0.05). Sodium and chloride had narrow optimal ranges for achieving a >90% viability. These findings were then tested in a prospective study (n = 10) and further verified. High hepatocyte viabilities (91.8+/-1.6% p = 0.036) and yields (2.56+/-0.48 x 10(10)) were achieved consistently, and P450IA1 activity was increased after sodium and chloride concentrations and pH in the perfusates were controlled. The physiological mechanism by which sodium and chloride affects hepatocyte viability during porcine liver digestion is discussed.

Increased sensitivity to the C-X-C chemokine CINC/gro in a model of chronic inflammation

OBJECTIVE

The C-C chemokine MCP-1 elicits significant neutrophil emigration in rats with chronic adjuvant-induced inflammation, but not in naive animals. We examined responses to the C-X-C chemokine CINC/gro to determine whether this class of chemokine elicits altered neutrophil responses during chronic inflammation.

METHODS

CINC/gro was superfused over mesenteric venules of naive rats or animals with chronic adjuvant-induced vasculitis. Antibodies were used to characterize adhesive mechanisms.

RESULTS

CINC/gro elicited leukocyte transendothelial migration in adjuvant-immunized rats at 100-fold lower concentrations than required to elicit transmigration in naive animals. In both groups, neutrophils constituted > 95% of the leukocytes recruited by CINC/gro. Using in vitro chemotaxis assays, neutrophils from control and adjuvant-immunized rats responded equally to CINC/gro, suggesting differences in migration were not related to neutrophil phenotype. Differences in adhesion molecule usage were noted in vivo. In control animals, CD18 antibodies blocked CINC/gro-induced neutrophil adhesion and emigration. In adjuvant-immunized animals, an alpha 4-integrin antibody reduced adhesion and emigration, while a CD18 antibody selectively inhibited emigration.

CONCLUSIONS

This study demonstrates increased sensitivity to a C-X-C chemokine in a model of chronic inflammation, implicates the alpha 4-integrin in neutrophil adhesion, and demonstrates that CD18 mediates leukocyte transendothelial migration independent from firm adhesion.

Alpha 4 integrin-dependent leukocyte recruitment does not require VCAM-1 in a chronic model of inflammation

Rats immunized with Mycobacterium butyricum in Freund's adjuvant develop a chronic vasculitis, with large increases in leukocyte rolling and adhesion in mesenteric postcapillary venules that are significantly inhibited with an alpha 4 integrin Ab. Using intravital microscopy to visualize chronically inflamed microvessels, we demonstrated that alpha 4 integrin-dependent leukocyte rolling and adhesion was inhibited with a beta 1 integrin, but not a beta 7 integrin Ab. To date, VCAM-1 has been presumed to be the primary ligand for alpha 4 beta 1 integrin in the vasculature. However, alpha 4 beta 1 integrin-dependent interactions were not reduced by monoclonal or polyclonal VCAM-1 Abs or a VCAM-1 antisense oligonucleotide despite increased VCAM-1 expression in the mesenteric vasculature. To ensure that the VCAM-1 Abs were functional and used at saturating concentrations, blood from Ab-treated rats was perfused over monolayers of CHO cells transfected with rat VCAM-1. Sufficient alpha 4 integrin or VCAM-1 Ab was present to inhibit leukocyte interactions with rat VCAM-1 by 95-100%. Under in vitro flow conditions, only mononuclear leukocytes were recruited from blood of control rats onto purified VCAM-1. However, neutrophils were also recruited onto VCAM-1 from whole blood of adjuvant-immunized animals via alpha 4 integrin. Another ligand for alpha 4 beta 1 integrin is the connecting segment-1 (CS-1) region of fibronectin. An Ab to the CS-1 portion of fibronectin, which did not reduce rolling and adhesion in adjuvant arthritis animals, completely inhibited leukocyte adhesion to CS-1 under static conditions. These findings provide the first evidence that alpha 4 beta 1 integrin-dependent leukocyte rolling and adhesion can occur in vivo via a mechanism other than VCAM-1.

A biodialysis system for liver support tested in a porcine hepatic failure model

BACKGROUND

A practical liver support system for patients in fulminant hepatic failure (FHF) remains a needed therapeutic modality. A new method of bioartificial liver support, the liver biodialysis system (LBDS), is described.

METHODS

Porcine hepatocytes, removed from direct contact with the treated subject's circulation, are in culture in a bioreactor which is combined in a dialysis circuit for patient treatment. The LBDS was tested in a porcine ischaemic hepatic failure model.

RESULTS

The viable hepatocyte content of the bioreactor was 2.49 +/- 0.72 x 10(10). Cells remained viable in culture throughout the experiments (30 +/- 3 h) without evidence of immunological damage. A decrease in the degree of accumulation in the blood of ammonia (P < 0.02) and of 14 amino acids (P < 0.001) was achieved by the LBDS. Cerebral perfusion pressure was maintained at significantly higher levels in LBDS-treated animals (P < 0.05).

CONCLUSIONS

In the LBDS, hepatocytes in large numbers and satisfactory culture conditions in a bioreactor have sustained viability and function. When combined in a dialysis circuit for the treatment of FHF pigs, immune reactions between the blood and hepatocytes were prevented and beneficial metabolic effects were observed.

Outcomes of the Kaiser Permanente Tele-Home Health Research Project

CONTEXT

Level of acuity and number of referrals for home health care have been escalating exponentially. As referrals continue to increase, health care organizations are encouraged to find more effective methods for providing high-quality patient care with cost savings.

OBJECTIVE

To evaluate the use of remote video technology in the home health care setting as well as the quality, use, patient satisfaction, and cost savings from this technology.

DESIGN

Quasi-experimental study conducted from May 1996 to October 1997.

SETTING

Home health department in the Sacramento, Calif, facility of a large health maintenance organization.

PARTICIPANTS

Newly referred patients diagnosed as having congestive heart failure, chronic obstructive pulmonary disease, cerebral vascular accident, cancer, diabetes, anxiety, or need for wound care were eligible for random assignment to intervention (n = 102) or control (n = 110) groups.

INTERVENTION

The control and intervention groups received routine home health care (home visits and telephone contact). The intervention group also had access to a remote video system that allowed nurses and patients to interact in real time. The video system included peripheral equipment for assessing cardiopulmonary status.

MAIN OUTCOME MEASURES

Three quality indicators (medication compliance, knowledge of disease, and ability for self-care); extent of use of services; degree of patient satisfaction as reported on a 3-part scale; and direct and indirect costs of using the remote video technology.

RESULTS

No differences in the quality indicators, patient satisfaction, or use were seen. Although the average direct cost for home health services was $1830 in the intervention group and $1167 in the control group, the total mean costs of care, excluding home health care costs, were $1948 in the intervention group and $2674 in the control group.

CONCLUSIONS

Remote video technology in the home health care setting was shown to be effective, well received by patients, capable of maintaining quality of care, and to have the potential for cost savings. Patients seemed pleased with the equipment and the ability to access a home health care provider 24 hours a day. Remote technology has the potential to effect cost savings when used to substitute some in-person visits and can also improve access to home health care staff for patients and caregivers. This technology can thus be an asset for patients and providers.

Endothelin-1 causes P-selectin-dependent leukocyte rolling and adhesion within rat mesenteric microvessels

Endothelin-1 (ET-1) is a potent vasoconstrictor postulated to play a role in hypertension, ischemia-reperfusion, and atherosclerosis. In addition to these contributions, it has been also proposed to induce leukocyte-endothelial cell interactions. The aim of the present study was to assess the mechanisms of action of ET-1 on leukocyte recruitment in vivo. Intravital microscopy of the rat mesenteric postcapillary venules was used. Ten minutes after 1 nM ET-1 superfusion, a significant increase in leukocyte rolling (77.5 +/- 22.6 vs. 20.5 +/- 4.5 cells/min) and adhesion (15.5 +/- 2.9 vs. 3.0 +/- 0.8 cells/100 micrometer) but not emigration was observed. These effects were found not to be mediated by mast cell activation. No platelet-endothelial cell interactions were detected in this in vivo system and furthermore, flow cytometry analysis revealed no increase of P-selectin expression in rat platelets on ET-1 stimulation. Pretreatment of animals with an anti-rat P-selectin monoclonal antibody (mAb) dramatically reduced leukocyte rolling and adhesion by 100 and 94% respectively when compared with control mAb-treated animals. At this dose of ET-1, a very transient decrease in shear rate was detected, arteriolar diameter was significantly reduced but venular diameter remained unchanged. A similar mechanical reduction in blood flow did not induce leukocyte recruitment. Thus this study demonstrates that ET-1 can directly cause significant leukocyte rolling and adhesion adding to its potential pathophysiological role in the development of disease states of the cardiovascular system.

Observer variability in interpretation of abdominal radiographs of infants with suspected necrotizing enterocolitis

We examined (1) the observer variability (both interobserver and intraobserver) in interpretation of abdominal radiographs of infants with suspected necrotizing enterocolitis (NEC), (2) the interobserver variability for individual radiologic signs used to diagnose NEC, and (3) the influence of experience in determining the extent of observer variability. Our hypotheses were (1) there would be considerable observer variability in interpretation of abdominal radiographs of infants with suspected NEC; (2) the extent of observer variability would differ for individual radiologic signs of NEC; and (3) the extent of observer variability would be determined by the observer's experience. The participants included 12 observers: two pediatric radiologists, four attending neonatologists, three neonatal fellows, and three pediatric residents. The participating observers under similar interpretation conditions, twice independently, interpreted the same 40 pairs of abdominal radiographs from infants with suspected NEC. The interval between the two interpretations was 3 to 6 months. Intraobserver and interobserver variability was assessed by applying the Kappa statistic to the radiologic signs of NEC for the two separate interpretations. The observers were blinded to patient's identity and the clinical course. Each observer recorded the absence, suspicion, or presence of (1) intestinal distention, (2) air fluid levels, (3) bowel wall thickening, (4) pneumatosis intestinalis, (5) portal venous gas, (6) pneumoperitoneum, and (7) NEC. We found low intraobserver and interobserver agreements. There was considerable variation in observer variability for individual radiologic signs. Trained observers performed better than intraining observers. We conclude that the radiologic signs in isolation should not be considered reliable. We recommend studies to formulate more objective criteria for many of the radiographic features of NEC. Standardization and periodic enforcement of these criteria among observers could reduce observer variability. We suggest that, to decrease both false-negative and false-positive interpretation, an experienced observer should always review the radiographs of infants with suspected NEC.