Inversion Recovery Ultrashort TE MR Imaging of Myelin is Significantly Correlated with Disability in Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE

MR imaging has been widely used for the noninvasive evaluation of MS. Although clinical MR imaging sequences are highly effective in showing focal macroscopic tissue abnormalities in the brains of patients with MS, they are not specific to myelin and correlate poorly with disability. We investigated direct imaging of myelin using a 2D adiabatic inversion recovery ultrashort TE sequence to determine its value in assessing disability in MS.

MATERIALS AND METHODS

The 2D inversion recovery ultrashort TE sequence was evaluated in 14 healthy volunteers and 31 patients with MS. MPRAGE and T2-FLAIR images were acquired for comparison. Advanced Normalization Tools were used to correlate inversion recovery ultrashort TE, MPRAGE, and T2-FLAIR images with disability assessed by the Expanded Disability Status Scale.

RESULTS

Weak correlations were observed between normal-appearing white matter volume (R = -0.03, P = .88), lesion load (R = 0.22, P = .24), and age (R = 0.14, P = .44), and disability. The MPRAGE signal in normal-appearing white matter showed a weak correlation with age (R = -0.10, P = .49) and disability (R = -0.19, P = .31). The T2-FLAIR signal in normal-appearing white matter showed a weak correlation with age (R = 0.01, P = .93) and disability (R = 0.13, P = .49). The inversion recovery ultrashort TE signal was significantly negatively correlated with age (R = -0.38, P = .009) and disability (R = -0.44; P = .01).

CONCLUSIONS

Direct imaging of myelin correlates with disability in patients with MS better than indirect imaging of long-T2 water in WM using conventional clinical sequences.

Musculoskeletal ultrasound for intra-articular bleed detection: a highly sensitive imaging modality compared with conventional magnetic resonance imaging

Essentials The best imaging modality for joint blood detection in hemophilia is unknown. Blood appearance and detection thresholds were studied with ultrasound and conventional MRI. Ultrasound is sensitive to low volume and concentration of blood, whereas conventional MRI is not. The findings establish the validity of ultrasound for rapid bleed detection in hemophilia care.

SUMMARY

Background There is increasing demand for musculoskeletal ultrasound (MSKUS) to detect hemophilic joint bleeding, but there is uncertainty regarding blood detection concentration thresholds or if magnetic resonance imaging (MRI) is more accurate. Aims Compare the sensitivity of blood detection by MSKUS and MRI. Methods Increasing blood concentrations in plasma were imaged with MSKUS and MRI 1-2 h, 3-4 days and 7 days after blood withdrawal in vitro, and after injection into cadaveric pig joints. Additionally, effusions in the joints of two patients with hemophilia joints were imaged, followed by aspiration. MSKUS was performed using an 8-18-MHz linear transducer; MRI was performed at 3T using T1-weighted and T2-weighted fat-suppressed sequences. Images were reviewed by a hematologist certified in MSKUS and a musculoskeletal radiologist. Results MSKUS permitted the detection of blood in vitro and in pig joint spaces at concentrations as low as 5%, demonstrated by the presence of echogenic signals that were absent with plasma alone. In contrast, no differences between fluids were discernible on the T1-weighted or T2-weighted MRI images. Results were confirmed in the two patients with hemophilia. Blood clots demonstrated varying and dynamic echogenicity patterns over time and, using MRI, were visualized best with T2 sequences. Conclusion MSKUS is extremely sensitive in detecting low concentrations of intra-articular blood and in discriminating between bloody and non-bloody fluid, whereas conventional MRI is not. These observations demonstrate the advantages of MSKUS over MRI in detecting intra-articular blood, and show that MSKUS is ideal for rapid bleed detection in the clinic.

Health care resource use and costs associated with possible side effects of high oral corticosteroid use in asthma: a claims-based analysis

BACKGROUND

The objective of this study was to estimate the prevalence of possible oral corticosteroid (OCS)-related side effects and health care resource use and costs in patients with asthma.

METHODS

This was a cross-sectional, matched-cohort, retrospective study using a commercial claims database. Adults with asthma diagnosis codes and evidence of asthma medication use were studied. Patients with high OCS use (≥30 days of OCS annually) were divided into those who did versus those who did not experience OCS-related possible side effects. Their health care resource use and costs were compared using linear regression or negative binomial regression models, adjusting for age, sex, geographic region, Charlson Comorbidity Index score, and chronic obstructive pulmonary disease status.

RESULTS

After adjustment, high OCS users with possible side effects were more likely to have office visits (23.0 vs 19.6; P<0.001) and hospitalizations (0.44 vs 0.22; P<0.001) than those without possible side effects. Emergency department visits were similar between the groups. High OCS users with possible side effects had higher adjusted total annual mean health care costs ($25,168) than those without such side effects ($21,882; P=0.009).

CONCLUSION

Among high OCS users, patients with possible OCS-related side effects are more likely to use health care services than those without such side effects. Although OCS may help control asthma and manage exacerbations, OCS side effects may result in additional health care resource use and costs, highlighting the need for OCS-sparing asthma therapies.

Control of metamorphic buffer structure and device performance of In(x)Ga(1-x)As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique's precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10(6) cm(-2)), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance-voltage responses with small frequency dispersion. A promising interface trap density of 3 × 10(12) eV(-1) cm(-2) in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems.

A comprehensive, multispecialty approach to an acute exacerbation of chronic central pain in a tetraplegic

STUDY DESIGN

We present a case report describing the multidisciplinary treatment of a tetraplegic spinal cord injury (SCI) patient who developed an acute exacerbation of chronic central pain.

OBJECTIVE

To bring further awareness to the importance of using a comprehensive, multidisciplinary approach in treating acute exacerbation of chronic central pain in SCI patients.

SETTING

University of California Irvine Medical Center, Orange, CA, USA.

CASE REPORT

We present a 34-year-old man with a past medical history of C5 American Spinal Injury Association B tetraplegia secondary to a surfing accident 8 years prior, central pain syndrome, spasticity, autonomic dysreflexia and anxiety who arrived at the emergency room with a 1-month history of worsening acute on chronic pain refractory to opioid escalation. The multispecialty treatment plan included treatment of the patient's urinary tract infection by the primary medicine service, management of the patient's depression by the psychiatric service, treatment of bowel obstruction by general surgery and adjustment of pain medications by pain management. The patient was found to have stable neurological findings, neuroimaging unchanged from prior imaging and a urinary tract infection. Hospitalization was complicated by severe colonic dilation that required disimpaction by general surgery.

CONCLUSION

The treatment of this patient's acutely worsened central pain highlights the importance of applying a multidisciplinary approach to SCI patients with an acute exacerbation of chronic central pain. In this case, the multispecialty treatment plan included treatment of the patient's urinary tract infection by the primary medicine service, management of the patient's depression by the psychiatric service, treatment of bowel obstruction by general surgery, and adjustment of pain medications by pain management.

Spinal 5-HT3 receptors facilitate behavioural hypersensitivity induced by elevated calcium channel alpha-2-delta-1 protein

BACKGROUND

Peripheral nerve injury induces up-regulation of the calcium channel alpha-2-delta-1 proteins in the dorsal root ganglia and dorsal spinal cord that correlates with neuropathic pain development. Similar behavioural hypersensitivity was also observed in injury-free transgenic (TG) mice over-expressing the alpha-2-delta-1 proteins in neuronal tissues. To investigate pathways regulating alpha-2-delta-1 protein-mediated behavioural hypersensitivity, we examined whether spinal serotonergic 5-HT3 receptors are involved similarly in the modulation of behavioural hypersensitivity induced by either peripheral nerve injury in a nerve injury model or neuronal alpha-2-delta-1 over-expression in the TG model.

METHODS

The effects of blocking behavioural hypersensitivity in these two models by intrathecal or systemic injections of 5-HT3 receptor antagonist, ondansetron, were compared.

RESULTS

Our data indicated that the TG mice displayed similar behavioural hypersensitivities to non-painful mechanical stimulation (tactile allodynia) and painful thermal stimulation (thermal hyperalgesia) as that observed in the nerve injury model. Interestingly, tactile allodynia and thermal hyperalgesia in both models can be blocked similarly by intrathecal, but not systemic, injection of ondansetron.

CONCLUSIONS

Our data suggest that spinal 5-HT3 receptors are likely to play a role in alpha-2-delta-1-mediated behavioural hypersensitivities through a descending serotonergic facilitation.

Dual inversion recovery ultrashort echo time (DIR-UTE) imaging and quantification of the zone of calcified cartilage (ZCC)

OBJECTIVE

To develop ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques to image the zone of calcified cartilage (ZCC), and quantify its T2*, T1 and T1ρ.

DESIGN

In this feasibility study a dual inversion recovery UTE (DIR-UTE) sequence was developed for high contrast imaging of the ZCC. T2* of the ZCC was measured with DIR-UTE acquisitions at progressively increasing TEs. T1 of the ZCC was measured with saturation recovery UTE acquisitions at progressively increasing saturation recovery times. T1ρ of the ZCC was measured with spin-locking prepared DIR-UTE acquisitions at progressively increasing spin-locking times.

RESULTS

The feasibility of the qualitative and quantitative DIR-UTE techniques was demonstrated on phantoms and in six cadaveric patellae using a clinical 3 T scanner. On average the ZCC has a short T2* ranging from 1.0 to 3.3 ms (mean ± standard deviation = 2.0 ± 1.2 ms), a short T1 ranging from 256 to 389 ms (mean ± standard deviation = 305 ± 45 ms), and a short T1ρ ranging from 2.2 to 4.6 ms (mean ± standard deviation = 3.6 ± 1.2 ms).

CONCLUSION

UTE MR based techniques have been developed for high resolution imaging of the ZCC and quantitative evaluation of its T2*, T1 and T1ρ relaxation times, providing non-invasive assessment of collagen orientation and proteoglycan content at the ZCC and the bone cartilage interface. These measurements may be useful for non-invasive assessment of the ZCC, including understanding the involvement of this tissue component in osteoarthritis.

Abstract P4-03-01: Distance of breast cancer from the skin influence axillary nodal metastasis

Background: In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Moreover, cancers underlying skin are willing to access to the lymphatics and cause lymphatic dissemination. Therefore, there seems an association between proximity of breast cancer to the skin and the incidence of axillary node positivity or local recurrence.

The aim of this study was to determine whether distance of breast cancers from the skin affects the the clinical and pathologic features including the likelihood of axillary nodal metastases, ipsilateral breast cancer recurrence, and recurrence free survival.

Methods: Between January 2003 and December 2009, data were collected prospectively regarding 1005 consecutive breast cancer patients who underwent surgical treatment. The exclusion criteria were non-invasive carcinoma (e.g. Ductal Carcinoma In Situ), prior breast surgery, previous radiotherapy or neo-adjuvant chemotherapy and previous endocrine therapy. The distance of the tumor from the skin surface was measured from the skin to the most anterior hypoechoic leading edge of the lesion.

Results: A total of 891 patients were included in the statistical analysis, 603(68%) had no axillary nodal metastasis, 288(32%) had axillary nodal metastasis. Distance of breast cancer from the skin less than 3mm induced more axillary nodal metastasis (P = 0.039). However, there was no statistical significant correlation between distance of breast cancer from the skin less than 3mm and ipsilateral breast tumor recurrence (P = 0.788) or recurrence-free survival (P = 0.353).

Conclusion: Breast cancers located closer to the skin have a higher incidence of axillary nodal metastasis. When evaluating a breast cancer patient and considering the risk of nodal metastasis the distance of the tumor from the skin should be considered.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-01.

Using Administrative Claims Data to Estimate Virologic Failure Rates among Human Immunodeficiency Virus–Infected Patients with Antiretroviral Regimen Switches

Objective. To develop and validate a claims signature model that estimates proportions of HIV-infected patients in administrative claims databases who switched combination antiretroviral therapy (cART) regimens because of virologic failure. Methods. The authors used an HIV-specific registry (development data set) to develop logistic regression models to estimate odds of virologic failure among patients who switched cART regimens. Models were validated in a sample of administrative claims with laboratory values (validation data set). The final model was applied to an application data set as a worked example. Results. There were 1691, 1073, and 3954 eligible patients with cART switches in the development, validation, and application data sets, respectively. In the development data set, virologic failure before a switch was observed 21.8% of the time. Failure more likely caused the regimen switch among patients who were treatment experienced, had been receiving their baseline regimen for > 180 days, had ≥ 2 or more physician visits within 90 days, had > 1 HIV RNA or CD4 cell count test within 30 days, had any resistance test within 180 days, or had a change in regimen type. The final model had good discriminatory ability (C = 0.885) and fit (Hosmer-Lemeshow P = 0.8692). Failure was estimated to occur in 18.9% (v. 18.6% observed) of switches in the validation data set and 13.8% in the application data set. Conclusions. This claims signature model allows payers to use claims data to estimate virologic failure rates in their patient populations, thereby better understanding plan costs of failure.

Cost-effectiveness of 21-gene assay in node-positive, early-stage breast cancer

OBJECTIVE

To assess impact on health outcomes and healthcare expenditures of adopting a 21-gene assay for women with early-stage, minimally node-positive, estrogen receptor-positive (N (1-3)/ER) HER2-negative breast cancer.

STUDY DESIGN

We adapted a deterministic decision-analytic model to estimate costs and quality-of-life outcomes associated with chemotherapy, adverse events, supportive care, recurrence, and second primary cancers for usual care compared with care determined by the 21-gene assay recurrence score, where 71% and 54% of women, respectively, were treated with adjuvant chemotherapy. Model input data were based on national statistics, published literature, physician surveys, and Medicare Part B prices.

METHODS

Annual numbers of events were multiplied by quality-adjusted life-years (QALYs) lost and costs to estimate net health and economic impacts of each strategy. Analyses were from a managed care payer perspective for the US population.

RESULTS

Patients receiving the assay were predicted to gain 0.127 QALY and save $4359 annually from avoiding chemotherapy, adverse events, supportive care, and secondary primary tumors. For a 2-million member plan, net gains were 4.44 QALYs/year and savings were $13,476/year. Cost savings were greater for the Medicare population. Although overall results were sensitive only to reduced impact of testing and chemotherapy costs, they were still highly cost-effective (incremental cost-effectiveness ratio <$20,000/QALY).

CONCLUSIONS

Use of a 21-gene assay in patients with early-stage N (1-3)/ER HER2-negative breast cancer may improve health outcomes and add no incremental cost, thereby providing valuable insight for health plans, the Centers for Medicare and Medicaid Services, and clinicians regarding coverage policies and treatment decisions.

Cost effectiveness of atazanavir-ritonavir versus lopinavir-ritonavir in treatment-naïve human immunodeficiency virus-infected patients in the United States

OBJECTIVE

To evaluate lifetime cost effectiveness of atazanavir-ritonavir (ATV + r) versus lopinavir-ritonavir (LPV/r), both with tenofovir-emtricitabine, in US HIV-infected patients initiating first-line antiretroviral therapy.

METHODS

A Markov microsimulation model was developed to calculate quality-adjusted life-years (QALYs) based on CD4 and HIV RNA levels, coronary heart disease (CHD), AIDS, opportunistic infections (OIs), diarrhea, and hyperbilirubinemia. A million-member cohort of HIV-1-infected, treatment-naïve adults progressed at 3-month intervals through eight health states. Baseline characteristics, virologic suppression, cholesterol changes, and diarrhea and hyperbilirubinemia rates were based on 96-week CASTLE trial results. HIV mortality, OI rates, adherence, costs, utilities, and CHD risk were from literature and experts.

LIMITATIONS

The incremental cost-effectiveness ratio (ICER) may be overestimated because the ATV + r treatment effect was based on an intention-to-treat analysis. The QALY weights used for diarrhea, hyperbilirubinemia, and CHD events are uncertain; however, the ICER remained < $50,000/QALY when these values were varied in sensitivity analyses.

RESULTS

ATV + r patients received first-line therapy longer than LPV/r patients (97.3 vs. 70.7 months), had longer quality-adjusted survival (11.02 vs. 10.76 years), similar overall survival (18.52 vs. 18.51 years), and higher costs ($275,986 vs. 269,160). ATV+r [corrected] patients had lower rates of AIDS (19.08 vs. 20.05 cases/1000 patient-years), OIs (0.44 vs.0.52), diarrhea (1.27 vs. 6.26), and CHD events(5.44 vs. 5.51), but higher hyperbilirubinemia rates (6.99 vs. 0.25. ATV + r added 0.26 QALYs at a cost of $6826, for $26,421/QALY.

CONCLUSIONS

By more effectively reducing viral load with less gastrointestinal toxicity and a better lipid profile, ATV + r lowered rates of AIDS and CHD, increased quality-adjusted survival, and was cost effective (< $50,000/QALY) compared with LPV/r.

Care of asthma patients in relation to guidelines

Clinical asthma care may have to change to be brought in line with Expert Panel Report 3 (EPR3) guidelines, which recommend increased intensity of therapy (steps) to treat uncontrolled asthma. This study determined if asthma therapy steps can be identified using claims data and if patients have appropriate step-up in therapy if their disease is not controlled. A cohort study was performed using an administrative claims database and involving patients 12-64 years old with uncontrolled asthma events (either impairment or risk). Patients were assigned to a preindex step (6 months before the index date) and postindex steps (1 year after the index date). The primary study outcome was a change in therapy steps. We used logistic regression to identify variables predictive of an increase in step. Our algorithm for assigning steps appeared internally valid; patients identified as being at higher steps saw more specialists and had higher levels of asthma risk. Among 14,781 patients for which a step-up option existed, 12.4-41.3% had a step-up in therapy after an uncontrolled asthma event. For all steps, high-risk patients had higher odds of having a step-up in therapy than low-risk patients. The odds ratio for appropriate therapy increased with increasing baseline step: from 1.50 for step 2 versus step 1, to 11.41 for step 5 versus step 1. Steps can be assigned using claims data. Bringing care in line with EPR3 guidelines will require significant changes from current practice but will improve quality by reducing use of oral corticosteroids and increasing use of inhaled steroids.

Poor disease control among insured users of high-dose combination therapy for asthma

Adherence to asthma treatment may not completely prevent exacerbations. Clinical trial results indicate that many highly adherent asthma patients still have symptoms. Little is known about the level of control achieved by adherent patients outside clinical trials. This study was designed to evaluate the extent of asthma control among insured patients who were highly adherent to combination controller therapy. We used an administrative claims database for this cohort study of patients aged 12-64 years. Patients were newly treated with fluticasone, 500 micrograms/salmeterol, 50 micrograms, between January 1, 2003 and June 30, 2004. Patients were stratified according to adherence levels: low (<50%), moderate (50-74%), and high (> or =75%). We compared rates of poor control. A logistic regression model was used to control for baseline differences. Among 3357 patients, the mean age was 40.5 +/- 13.6 years, and 64.1% were women. Sixty-one percent had low adherence, 20% had moderate adherence, and 19% had high adherence. Highly adherent patients were older, and more used fluticasone, 250 micrograms/salmeterol, 50 micrograms, during the preindex period than the other groups. Even after starting high-dose fluticasone/salmeterol, many patients with low, moderate, and high adherence had indicators of poor symptom control (28.9% [587/2030], 30.6% [209/682], and 30.7% [198/645], respectively). Patients who were highly adherent and used additional controller medications had rates of poor control that ranged from 23.1 to 31.2%. After adjusting for age, gender, and baseline characteristics, results were similar. Many patients continue to have poor asthma control despite being adherent to high-dose combination therapy or using additional controller medications.

Adherence and persistence with omalizumab and fluticasone/salmeterol within a managed care population

Asthma control requires adherence with pharmacologic therapy. A medication's mode of delivery may affect adherence. The purpose of this study was to compare medication persistence and adherence between patients newly treated with either an inhaled or injected asthma medication. Using a propensity-score-matched retrospective cohort study, we evaluated medication persistence and adherence over 1 year in adult asthma patients newly treated with omalizumab or fluticasone (500 microg)/salmeterol (50 microg) (FSC 500/50). Kaplan-Meier analysis was conducted to compare persistence between users of FSC 500/50 and omalizumab using the log-rank test. We conducted four sensitivity analyses. After propensity matching, the study sample included 213 omalizumab patients and 426 FSC 500/50 patients, with no statistically significant differences between groups on baseline measures. Mean adherence rates were 64.6% for omalizumab and 29.5% for FSC 500/50 (p < 0.0001). Fifty-four percent of omalizumab users were persistent at 1 year compared with 18.5% of FSC 500/50 users (p < 0.0001). In sensitivity analyses, we stratified patients by evidence of allergy and the results did not change. Adherence was more than twice as high and persistence was almost twice as high among omalizumab compared with FSC 500/50 users. The direction of our findings was consistent across all sensitivity analyses. In both omalizumab and FSC 500/50 cohorts, persistence decreased substantially over 1 year. Our study suggests that injected medications may have advantages in asthma treatment. A comprehensive program to improve adherence should address not just administration route but also patient factors that prevent proper medication use.

Endoscopic ultrasound for the evaluation of Nissen fundoplication integrity: a blinded comparison with conventional testing

BACKGROUND

For patients whose symptoms develop after Nissen fundoplication, the precise mechanism of anatomic failure can be difficult to determine. The authors have previously reported the endosonographic hallmarks defining an intact Nissen fundoplication in swine and the known causes of failure. The current clinical trial tested the hypothesis that a defined set of endosonographic criteria can be applied to determine fundoplication integrity in humans.

METHODS

The study enrolled seven symptomatic and nine asymptomatic subjects at a mean of 6 years (range, 1-30 years) after Nissen fundoplication. A validated gastroesophageal reflux disease (GERD)-specific questionnaire and medication history were completed. Before endoscopic ultrasound (EUS), all the patients underwent complete conventional testing (upper endoscopy, esophagram, manometry, 24-h pH). A diagnosis was rendered on the basis of combined test results. Then EUS was performed by an observer blinded to symptoms, medication use, and conventional testing diagnoses. Because EUS and esophagogastroduodenoscopy (EGD) are uniformly performed in combination, the EUS diagnosis was rendered on the basis of previously established criteria combined with the EGD interpretation. The diagnoses then were compared to examine the contribution of EUS in this setting.

RESULTS

The technique and defined criteria were easily applied to all subjects. All symptomatic patients had heartburn and were taking proton pump inhibitors (PPI). No asymptomatic patients were taking PPI. All diagnoses established with combined conventional testing were detected on EUS with upper endoscopy. Additionally, EUS resolved the etiology of a low lower esophageal sphincter pressure in two symptomatic patients and detected the additional diagnoses of slippage in two subjects. Among asymptomatic subjects, EUS identified additional diagnoses in two subjects considered to be normal by conventional testing methods.

CONCLUSION

According to the findings, EUS is a feasible method for evaluating post-Nissen fundoplication hiatal anatomic relationships. The combination of EUS and EGD allows the mechanism of failure to be detected in patients presenting with postoperative symptoms after Nissen fundoplication.

The effect of medication adherence on health care utilization in bipolar disorder

A retrospective analysis of electronic prescription and medical claims representing approximately 1.4 million managed care commercial health plan members with mental health benefits was conducted. The effect of patient adherence to traditional mood-stabilizer therapy (lithium, valproate, carbamazepine, lamotrigine, or oxcarbazepine) for bipolar disorder on mental health-related hospitalization was assessed among 1,399 patients (mean age, 42.9 yr; 66.3% female) studied. Reduced adherence to traditional mood-stabilizing therapy (< 80%) in patients with bipolar disorder was associated with significantly greater risk of mental health-related, emergency room visits (odds ratio, 1.98; 95% confidence interval, 1.38-2.84) and inpatient hospitalizations (odds ratio, 1.71; 95% confidence interval, 1.27-2.32), even after adjusting for age, gender, and comorbidity.

Gastrointestinal bleeding rates among managed care patients newly started on cox-2 inhibitors or nonselective NSAIDs

OBJECTIVE

While cyclooxygenase-2 (COX-2) inhibitors were introduced to the U.S. market with the promise of less gastrointestinal (GI) toxicity than nonselective nonsteroidal anti-inflammatory drugs (NSAIDs), additional research is needed to examine this outcome in the naturalistic setting. The objective of this study was to examine whether use of COX-2 inhibitors is associated with reduced risk of GI bleed in a managed care population.

METHODS

Adult patients in a multistate managed care organization that were initiated on a nonselective NSAID between January 1999 and August 2002 were identified and matched using propensity scoring with patients in the same managed care organization that were initiated on a COX-2 inhibitor. Matching variables included age, gender, geographical state, comorbidity index, corticosteroid use, warfarin use, arthritis indication, and history of recent GI bleed. Patients were followed until they switched or discontinued their NSAID or COX-2 inhibitor, disenrolled from the health plan, developed a GI bleed, or reached the end of the 1-year follow-up period. A GI bleed was defined as an inpatient hospitalization for GI bleed or at least 2 medical claims with a primary diagnosis for GI bleed. The relative risk (RR) of GI bleed was calculated using proportional hazards regression.

RESULTS

Overall, 35,007 pairs of COX-2 inhibitor and nonselective NSAID users were evaluated. Mean age was 63 years, and 65% were female. There were 375 cases of GI bleed among 19,201 follow-up years for COX-2 users (19.5 cases per 1,000 person-years) versus 228 cases of GI bleed among 12,680 follow-up years for NSAID users (18.0 cases per 1,000 person-years). The risk of GI bleed was not significantly different for COX-2 users compared with nonselective NSAID users (RR 1.07; 95% confidence interval [CI], 0.90-1.26). Even among high-risk patients, there was no reduction in the risk of a GI bleed among users of COX-2 inhibitors (RR 0.995; 95% CI, 0.84 -1.19).

CONCLUSION

Overall, within this managed care population, COX-2 inhibitor users did not have a reduced risk of a GI bleed compared with patients with similar baseline characteristics using nonselective NSAIDs.

Comparison of costs and utilization between users of insulin lispro versus users of regular insulin in a managed care setting

OBJECTIVE

To compare medical and pharmacy costs and utilization between patients with diabetes who received insulin lispro versus regular human insulin.

METHODS

A retrospective analysis of medical and pharmacy claims was conducted among continuously enrolled users of insulin lispro or regular insulin during the identification period, March 1, 2000, through February 28, 2001, within a large managed care organization. This study improved upon the methodology used in previous studies by (a) stratifying (rather than 1:1 matching) individuals by their likelihood to use insulin lispro using the propensity score binning technique, and (b) refining the study inclusion criteria to include only patients with 3 or more fills of the insulin under study (lispro or regular) to exclude individuals who may have been on either product for a short time. Because the propensity score binning technique groups patients with similar baseline characteristics within strata (bins) and not among individual patients, almost the entire available sample is retained in the analysis, unlike propensity score matching, where large numbers of patients can be excluded depending on the matching scheme. Therefore, the propensity score binning technique, because it uses more complete information, is less likely to produce biased results. Patients were grouped into 5 bins (quintiles) based on their estimated likelihood to receive insulin lispro rather than regular insulin. The propensity score model used baseline characteristics of age, gender, comorbidities, use of oral antidiabetic medications, prescription copayment, and diabetes-related costs and utilization. Overall cost and utilization differences (lispro minus regular insulin) during the 12-month follow-up period were calculated using weights inversely proportional to variances of within-bin differences.

RESULTS

Of 6,436 patients, 1,972 (30.6%) received insulin lispro and 4,464 (69.4%) received regular insulin. The propensity score estimation produced 5 bins, each containing between 1,287 and 1,288 patients, utilizing all patients in the analysis. Patients in the lower-numbered propensity score quintiles were older, more likely to use oral antidiabetic medications, and had more comorbidities than those in the higher-numbered quintiles. As quintile number increased, the percentage of insulin lispro users also increased. The weighted mean annual cost difference (lispro minus regular insulin) per patient was + USD 79 (P < 0.001) for diabetes-related pharmacy cost, + USD 212 (P < 0.001) for total pharmacy cost, USD 75 (P < 0.857) for diabetes-related medical cost, USD 2,286 (P <0.011) for nondiabetes medical cost, and USD 2,327 (P = 0.072) for total medical cost.

CONCLUSIONS

Compared with regular insulin users, insulin lispro users incurred higher diabetes-related and total pharmacy costs but lower nondiabetes medical costs and similar total medical costs. Fewer hospitalizations among insulin lispro as compared with regular insulin users contributed to lower nondiabetes medical costs and similar total medical costs.

Repeated sequences of interspike intervals in baroresponsive respiratory related neuronal assemblies of the cat brain stem

Many neurons exhibit spontaneous activity in the absence of any specific experimental perturbation. Patterns of distributed synchrony embedded in such activity have been detected in the brain stem, suggesting that it represents more than "baseline" firing rates subject only to being regulated up or down. This work tested the hypothesis that nonrandom sequences of impulses recur in baroresponsive respiratory-related brain stem neurons that are elements of correlational neuronal assemblies. In 15 Dial-urethan anesthetized vagotomized adult cats, neuronal impulses were monitored with microelectrode arrays in the ventral respiratory group, nucleus tractus solitarius, and medullary raphe nuclei. Efferent phrenic nerve activity was recorded. Spike trains were analyzed with cycle-triggered histograms and tested for respiratory-modulated firing rates. Baroreceptors were stimulated by unilateral pressure changes in the carotid sinus or occlusion of the descending aorta; changes in firing rates were assessed with peristimulus time and cumulative sum histograms. Cross-correlation analysis was used to test for nonrandom temporal relationships between spike trains. Favored patterns of interspike interval sequences were detected in 31 of 58 single spike trains; 18 of the neurons with significant sequences also had short-time scale correlations with other simultaneously recorded cells. The number of distributed patterns exceeded that expected under the null hypothesis in 12 of 14 data sets composed of 4-11 simultaneously recorded spike trains. The data support the hypothesis that baroresponsive brain stem neurons operate in transiently configured coordinated assemblies and suggest that single neuron patterns may be fragments of distributed impulse sequences. The results further encourage the search for coding functions of spike patterns in the respiratory network.

Antigen-specific cancer immunotherapy using a GM-CSF secreting allogeneic tumor cell-based vaccine

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-transduced autologous tumor cell-based vaccines are currently one of the major forms of cancer vaccines. However, the preparation of GM-CSF-transduced autologous tumor vaccines is time-consuming and technically challenging. In addition, the host antigen presenting cells, rather than the tumor vaccine cells themselves, present tumor-specific antigens and prime the host T cells. Therefore, we tested the efficacy of antigen-specific allogeneic tumor vaccines. We used human papillomavirus 16 (HPV-16) E7 protein as a model tumor antigen, which is associated with the development of most cervical carcinoma. B16, a C57BL/6 (H-2(b)) derived melanoma cell line, was genetically engineered to produce GM-CSF alone (B16GM), HPV-16 E7 alone (B16E7), or both (B16GME7). These vaccine cells were injected into BALB/c (H-2(d)) mice (10(6) cells/mouse). Two weeks later, mice were challenged with 10(5) live HPV-16 E7(+) BL-1 (H-2(d)) tumor cells and monitored for tumor progression twice weekly. To determine the effective cell population in the antitumor immunity elicited by B16GME7, we carried out in vivo antibody depletion experiments using CD4 and CD8 specific antibodies. In addition, as a measure of the immune responses produced by B16GME7, we performed an in vitro cytotoxic T lymphocyte assay using a standard chromium release method. We found that all of the mice vaccinated with B16GME7 remained tumor free 49 days post-BL-1 challenge. In contrast, mice vaccinated with B16GM and B16E7 did not show any tumor protection against a similar dose of BL-1 cells. Furthermore, the antitumor immunity produced by B16GME7 was dependent on both CD4 and CD8 T cells. In addition, E7-specific cytotoxic T lymphocyte activity could be readily demonstrated in mice immunized with B16GME7. These results suggest that allogeneic tumor cells transduced with GM-CSF and the tumor antigen, HPV-16 E7, cannot only generate an E7-specific cytotoxic T lymphocytes response in vitro, but can also elicit a potent antitumor immune response against an E7 expressing tumor in vivo.

A noninvasive method for quantifying and distinguishing inflammatory skin reactions

BACKGROUND

The ribonuclease protection assay (RPA) represents a technology that allows detection of small amounts of intact RNA. Recent progress in understanding cytokine networks in the skin suggests that measurements of cytokine mRNA levels could provide a method to distinguish various reactions such as irritant contact dermatitis and allergic contact dermatitis that can occur in the skin.

OBJECTIVE

We attempted to differentiate and quantitate irritant and immunologic skin reactions by measuring mRNA levels.

METHODS

We have used the technique of tape stripping human skin to remove superficial cell layers and have extracted RNA from these skin samples. This RNA was used for RPA analysis.

RESULTS

By means of RPA analysis, we have demonstrated distinct cytokine profiles that appear to discriminate, for example, irritant from immunologic skin reactions.

CONCLUSION

We have shown that multiple cytokine mRNA levels can be defined in these RNA samples obtained from the skin. This approach assesses not only the cytokine gene profiles, but at the same time may quantify the severity of common irritant versus allergic skin reactions.

Antigen-specific immunotherapy for murine lung metastatic tumors expressing human papillomavirus type 16 E7 oncoprotein

An important goal of cancer immunotherapy is to prevent and treat tumor metastasis. We have previously reported a recombinant vaccinia-based vaccine (Sig/E7/LAMP-1) that demonstrated significant anti-tumor effect in a subcutaneous tumor challenge model. In this study, we investigated the potency of the Sig/E7/ LAMP-1 vaccine in preventing and treating metastatic tumors. A tumor metastasis model was generated by injecting human papillomavirus type 16 (HPV-16) E6/E7 expressing tumor cells, designated TC-1, into the tail vein of syngeneic C57BL/6 mice. All the naive mice injected with 1 x 10(6) TC-1 cells developed tumors confined exclusively to the lungs within 1 month. For in vivo tumor prevention experiments, mice were vaccinated with Sig/E7/ LAMP-1 followed by tumor challenge. While tumor growth was observed in all of the mice (10/10) in the control groups, 8 of 10 vaccinated mice (80%) remained tumor-free 2 months post-tumor challenge. For in vivo treatment experiments, mice were first inoculated with TC-1 cells and then vaccinated with Sig/E7/ LAMP-1. Treatment with Sig/E7/LAMP-1 was effective in eliminating preexisting tumor cells in 4 of 5 vaccinated mice. Most importantly, treatment with Sig/E7/LAMP-1 resulted in regression of fully established lung tumors in 10% (5/10) of vaccinated mice. Our data suggest that the Sig/E7/LAMP-1 vaccine is effective in controlling the hematogenous spread of TC-1 tumor cells. In addition, the TC-1 lung metastasis model can be used to test the efficacy of various E6/E7-specific vaccines and immunotherapeutic strategies.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Delayed radiosensitization of human colon carcinoma cells after a brief exposure to 2',2'-difluoro-2'-deoxycytidine (Gemcitabine)

We have shown that 2',2'-difluoro-2'-deoxycytidine (dFdCyd; Gemcitabine), a deoxycytidine analogue, is a potent radiation sensitizer when cells are exposed to it continuously for >16 h in low concentrations (in the range of 10 nM). However, the most common method of clinical administration is by short-term infusion (30-90 min). Therefore, we wished to determine under what conditions dFdCyd could produce radiosensitization after a relatively brief exposure to drug. We hypothesized that the long half-life of the phosphorylated metabolites of dFdCyd would produce long-lasting dNTP pool perturbation, particularly dATP pools, leading to radiosensitization hours or even days after the drug was removed from the medium. We tested this hypothesis by exposing HT29 human colon cancer cells for 2 h to clinically relevant concentrations of dFdCyd, removing the drug from the medium, and assessing radiation sensitivity up to 72 h later. We found that 100 nM dFdCyd, which was noncytotoxic, radiosensitized HT29 cells up to 48 h after drug removal. During this period, there was an increase in the S phase population, whereas by 72 h after drug removal, the cell cycle distribution resembled that seen under control conditions. dATP pools remained depleted throughout the 72-h period after drug treatment. This study supports the hypothesis that radiosensitization occurs in cells that are replicating DNA in the presence of perturbed dNTP pools. Furthermore, they may be useful in the design of rational clinical trials using dFdCyd as a radiation sensitizer.

Processing and routing of a membrane-anchored form of proneuropeptide Y

To investigate factors governing proteolytic processing and routing of biologically active peptides in the secretory pathway, cDNAs for preproneuropeptide Y (preproNPY) and preproneuropeptide Y fused to a membrane anchor were transfected into pituitary cells. The anchor was the transmembrane and COOH-terminal cytoplasmic domain of peptidylglycine alpha-amidating monooxygenase (PAM); these domains are essential for correct routing of integral membrane forms of PAM. Like proneuropeptide Y (proNPY), the integral membrane form of proNPY was a good substrate for the endogenous prohormone convertases, yielding soluble NPY stored in regulated secretory granules. Tethering of proNPY to the membrane resulted in only a small delay in the rate of cleavage to produce mature NPY and in the arrival of NPY in regulated secretory granules. In contrast, the COOH-terminal region of proNPY remained attached to the transmembrane/COOH-terminal domain of PAM and was rerouted to the vicinity of the trans-Golgi network, where integral membrane forms of PAM are concentrated. Thus, the COOH-terminal of proNPY cannot override the signals in the PAM membrane anchor.

Peptide biosynthetic processing: distinguishing prohormone convertases PC1 and PC2

To determine whether manipulation of time, temperature and intragranular pH could be used to distinguish the actions of two subtilisin-related endoproteases, PC1 and PC2, in peptide biosynthesis, the biosynthetic processing of proneuropeptide Y (proNPY) and proopiomelanocortin (POMC) was examined in pituitary cell lines. AtT-20 cells express PC1 and POMC endogenously; stably transfected AtT-20 lines expressing NPY or PC2 were studied. GH3 cells express PC2 endogenously; NPY-expressing GH3 transfectants were investigated. PC1 mediated rapid processing of NPY and POMC; PC1-dependent cleavages were relatively insensitive to 20 degrees C blockade (which arrests secretory pathway transport at the trans-Golgi network) and do not require an acidic intracellular compartment (as in secretory granules). PC2 mediated much slower processing of proNPY and POMC which was totally blocked at 20 degrees C and required an acidic intracellular compartment. Thus, kinetics, abolition of intracellular pH gradients, and incubation at reduced temperatures can be used to distinguish PC1 and PC2 actions in neuroendocrine cells.

Differential effects of the protein kinase C activator phorbol 12-myristate 13-acetate on calcium responses and secretion in adherent and suspended RBL-2H3 mucosal mast cells

Adhesion of RBL-2H3 mucosal mast cells to fibronectin-coated surfaces has been linked to changes in secretion and tyrosine kinase activity. We now show that adhesion affects the sensitivity of RBL cells to the protein kinase C activator phorbol 12-myristate 13-acetate (PMA). In suspended cells, PMA inhibited antigen-induced calcium influx (as measured by manganese influx) and changes in intracellular free calcium and had complex effects on antigen-stimulated secretion. However, in adherent cells PMA had little effect on these responses. Suspended cells only secreted in response to thapsigargin if they were co-treated with PMA, while adherent cells secreted in response to thapsigargin alone. The thapsigargin-induced secretion in adherent cells was inhibited by protein kinase C down-regulation and by the protein kinase C inhibitor GF 109203X, but not by calphostin C. We suggest that protein kinase C is constitutively activated in adherent cells, possibly due to modification of the regulatory domain of the enzyme.

Radiosensitization of pancreatic cancer cells by 2',2'-difluoro-2'-deoxycytidine

PURPOSE

We have reported that the deoxycytidine analog 2',2'difluoro-2'-deoxycytidine (dFdCyd) is a potent radiosensitizer of HT29 human colon cancer cells probably through its effects on intracellular deoxyribonucleotide (dNTP) pools. Because dFdCyd has activity against pancreatic cancer in clinical trials, we wished to determine if dFdCyd would radiosensitize human pancreatic cancer cells.

METHODS AND MATERIALS

We assessed the effect of dFdCyd on radiation sensitivity of two human pancreatic cancer cell lines, Panc-1 and BxPC-3. To begin to investigate the mechanism of sensitization, we determined the effect of dFdCyd on dNTP pools and cell cycle distribution.

RESULTS

We found that dFdCyd produced radiation enhancement ratios of 1.7-1.8 under noncytotoxic conditions in both cell lines. Sensitization was not associated with intracellular levels of 2',2'-difluoro-2'-deoxycytidine triphosphate, the cytotoxic metabolite of dFdCyd, but occurred when dATP pools were depleted below the level of approximately 1 micromolar. Although both cell lines showed substantial cell cycle redistribution after drug treatment, the flow cytogram of the BxPC-3 cells would not, by itself, be anticipated to result in increased radiation sensitivity.

CONCLUSIONS

These findings demonstrate that dFdCyd is a potent radiation sensitizer of human pancreatic cancer cells and support the development of a clinical protocol using combined dFdCyd and radiation therapy in the treatment of pancreatic cancer.

Effect of irradiation on bromodeoxyuridine incorporation in human colon cancer xenografts

PURPOSE

Although we have characterized the incorporation of the thymidine analog bromodeoxyuridine (BrdUrd) into human colon cancer xenografts under a wide variety of conditions, little is known about the effect of radiation on subsequent incorporation. Because clinical protocols include, as one component, BrdUrd administration after radiation, it was important to confirm that irradiation did not prevent subsequent BrdUrd incorporation. Therefore, we studied the effect of irradiation on BrdUrd incorporation into HT29 human colon cancer xenografts.

METHODS AND MATERIALS

Two types of experiments were performed. In the first, the effect of radiation on subsequent incorporation was measured. Tumors received doses of 0, 2, 8, and 12 Gy, animals were infused with BrdUrd for 4 days, and incorporation was assessed at the end of the infusion. In the second, the effect of radiation on the elimination of BrdUrd from tumors was determined. Animals were infused with BrdUrd, tumors were irradiated with either 0 or 12 Gy, and tumor incorporation of BrdUrd was measured 1 and 3 days later.

RESULTS

Radiation affected neither the incorporation into nor the elimination of BrdUrd from human tumor xenografts.

CONCLUSIONS

These findings support the feasibility of clinical trials interdigitating BrdUrd infusion and radiation.

Tyrosine phosphorylation of protein kinase C-delta in response to the activation of the high-affinity receptor for immunoglobulin E modifies its substrate recognition

The delta isoform of protein kinase C is phosphorylated on tyrosine in response to antigen activation of the high-affinity receptor for immunoglobulin E. While protein kinase C-delta associates with and phosphorylates this receptor, immunoprecipitation of the receptor revealed that little, if any, tyrosine-phosphorylated protein kinase C-delta is receptor associated. In vitro kinase assays with immunoprecipitated tyrosine-phosphorylated protein kinase C-delta showed that the modified enzyme had diminished activity toward the receptor gamma-chain peptide as a substrate but not toward histones or myelin basic protein peptide. We propose a model in which the tyrosine phosphorylation of protein kinase C-delta regulates the kinase specificity toward a given substrate. This may represent a general mechanism by which in vivo protein kinase activities are regulated in response to external stimuli.

Development of a rapid approach to identification of tyrosine phosphorylation sites: application to PKC delta phosphorylated upon activation of the high affinity receptor for IgE in rat basophilic leukemia cells

In rat basophilic leukemia cells (RBL-2H3) activation of the high affinity receptor for IgE induces tyrosine phosphorylation of PKC delta. We carried out solid phase synthesis of 15 amino acid long oligopeptides corresponding to the sequences around each of the 19 tyrosine residues in PKC delta. Only three oligopeptides, corresponding to tyrosine 52, 155, and 565, were phosphorylated when exposed to lyn kinase. Single mutants in each of these three tyrosine residues of PKC delta were prepared. Upon expression in the RBL-2H3 cells, only the mutant in tryosine 52 showed abolition of the IgE-antigen induced tyrosine phosphorylation.

Lack of dependence of 5-fluorodeoxyuridine-mediated radiosensitization on cytotoxicity

It has been proposed that fluoropyrimidine-mediated cytotoxicity and radiosensitization are closely correlated. We have shown that HT29 human colon cancer cells transfected with the E. coli dUTPase gene are resistant to 5-fluorodeoxyuridine (FdUrd)-mediated cytotoxicity, presumably through more effective elimination of dUTP. We used these cells to assess the association between radiosensitization and cytotoxicity produced by FdUrd. The radiation sensitivities of the clones expressing elevated dUTPase activity (dutE clones) were similar to those of untransfected HT29 cells or HT29 cells which had been transfected with only the expression vector for the E. coli gene (con clones). We found that FdUrd produced similar increases in radiation sensitivity regardless of dUTPase activity. Levels of dUTPase in the dutE clones remained elevated during the entire period of FdUrd exposure, demonstrating that the lack of difference between dutE and Con clones was not a reflection of down-regulation of dUTPase activity by FdUrd. Flow cytometry showed that all clones progressed past the G1/S-phase boundary and into early S phase during FdUrd treatment. These data suggest that the mechanisms of FdUrd-mediated cytotoxicity and radiosensitization are not closely linked. These findings, combined with our previous investigations, are consistent with the hypothesis that radiosensitization occurs in cells which progress past the G1/S-phase boundary in the presence of FdUrd.

Effects of subunit mutation on the rotational dynamics of Fc epsilon RI, the high affinity receptor for IgE, in transfected cells

Erythrosin-labeled immunoglobulin E (IgE) and time-resolved phosphorescence anisotropy were used to monitor the rotational dynamics of transfected wild-type (alpha beta gamma 2) and four mutant Fc epsilon RI receptors in the monomeric and dimeric state on P815 cells. Erythrosin-IgE bound to Fc epsilon RI on cells transfected with either beta or gamma subunits with truncated COOH-terminal cytoplasmic segments exhibit faster rotational motion than when bound to Fc epsilon RI on cells transfected with wild-type subunits. Deletion of the NH2-terminal cytoplasmic segment of the beta subunit or the COOH-terminal cytoplasmic segment of the alpha subunit does not cause any significant change in the anisotropy decay. Dimers of IgE-receptor complexes formed with anti-IgE monoclonal antibody B1E3 exhibit substantially slower anisotropy decays for all the receptor constructs used, including a receptor construct that only contains the ectodomain of the alpha subunit anchored to Chinese hamster ovary (CHO) cell membranes through a lipid tail. This loss of rotational motion of dimeric IgE-Fc epsilon RI complexes may be due to nonspecific entanglement or to specific interactions involving IgE or the extracellular portion of alpha. The results suggest that the beta and gamma subunits of the tetrameric alpha beta gamma 2 receptor participate in interactions with other membrane components even in the absence of receptor aggregation. The loss of such interactions may be related to the functional impairments previously determined for these mutants.

Alteration of lipid composition modulates Fc epsilon RI signaling in RBL-2H3 cells

We have used sonicated liposomes of phosphatidylcholine (PC), sphingomyelin (SM), or a mixture of cholesterol (chol) and PC to investigate the role of cellular lipid composition in Fc epsilon RI-mediated stimulation of RBL-2H3 cells. Overnight treatment with either PC or SM liposomes causes a substantial enhancement of antigen-stimulated degranulation and phospholipase A2 activity, whereas treatment with a PC/chol mixture results in partial inhibition of the antigen-stimulated response. The most consistent change in the cellular lipid composition that results from the PC and SM liposome treatments is an approximate 40% decrease in the chol/phospholipid (PL) ratio. The lipid treatments do not alter degranulation stimulated by AlF4- or by Ca2+ ionophore in the presence or absence of PMA, suggesting that lipid alteration affects a receptor-specific signaling process. The lipid treatments do not appear to alter antigen-stimulated tyrosine phosphorylation or Ca2+ mobilization. Possible involvement of protein kinase C (PKC) activation in the signal-enhancing effect of the PL treatments was investigated by using calphostin C and phorbol-12-myristol-13-acetate (PMA) to inhibit PKC activity and degranulation in RBL-2H3 cells. Both SM and PC treatment restore the antigen-mediated degranulation response that is inhibited by long-term treatment (> or = 16 h) with 100 nM PMA or short-term treatment (10 min) with 5 microM calphostin C. The results indicate that a decreased chol/PL ratio facilitates or enhances the receptor-mediated activation of a PKC-like pathway that plays an important role in Fc epsilon RI-stimulated degranulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Disparate modulation of plasma membrane protein lateral mobility by various cell permeabilizing agents

The mobility of a cell surface protein on cells osmotically swollen by treatment with several different cell permeabilizing agents retains specific restraints despite detachment of the plasma membrane from the cortical cytoskeleton. Fluorescence photobleaching recovery experiments indicate that the lateral diffusion constants of immunoglobulin E (IgE)-receptor complexes on the surface of rat basophilic leukemia cells increase 2-5x following permeabilization with streptolysin O or digitonin, with little change in their mobile fractions. Swelling by hypo-osmotic treatment in water enhances lateral diffusion of IgE-receptor complexes and raises the mobile fractions to near 100%. In contrast, swelling by treatment with filipin arrests lateral diffusion, although rotational mobility remains unhindered. Lateral mobility of a fluorescent lipid analogue remains unchanged under these conditions. Crosslinking by anti-IgE antibodies redistributes the IgE-receptor complexes into large patches on untreated cells and on cells swollen by permeabilization with streptolysin O or digitonin, but not on cells swollen by treatment with filipin. The results indicate a diversity of effects of the various permeabilizing agents on the mobility of membrane proteins. In particular, treatment with filipin appears to reorganize the plasma membrane into a network of fluid domains on a scale smaller than the bleaching spot size used (approximately 1.5 microns).

T-cell activation is potentiated by cytokines released by lesional psoriatic, but not normal, epidermis

BACKGROUND AND DESIGN

T-cell activation appears to be critical for the maintenance of psoriatic lesions. In this study, we determined whether cytokines released by epidermal cells from psoriatic lesions are providing signals that result in propagation of intralesional T-cell activation. Supernatants were obtained from epidermal cell cultures derived from skin biopsy specimens of psoriatic patients and normal subjects. These supernatants were added to purified normal CD4+ T cells activated via T-cell receptor (immobilized anti-CD3 and fibronectin) or via other activating pathways (anti-CDw60 or UM4D4).

RESULTS

Psoriatic supernatants (n = 9), but not normal supernatants (n = 7, P < .0006), potentiated T-cell stimulation with anti-CD3 and fibronectin to 172% +/- 41% over control stimulation levels. The degree of lesional psoriatic epidermal cell potentiation correlated with the clinical severity of the lesion (r = .82, P = .007). Psoriatic epidermal cytokine potentiation of T-cell activation was not limited to T-cell receptor mediated stimulation; potentiation of anti-CDw60-stimulated CD4+ T cells was also observed. Neutralizing antisera to interleukin 1 and interleukin 8, but not interleukin 6, were found to reduce only partly the observed potentiation of T-cell activation. To determine whether cyclosporine is down modulating T-cell-potentiating cytokine activity in psoriasis, we compared samples obtained during a double-blind clinical trial of intralesional cyclosporine. T-cell-potentiating activity from psoriatic lesional sites treated with cyclosporine was not significantly modulated relative to the activity derived from vehicle-treated or untreated sites.

CONCLUSION

These data demonstrate that lesional psoriatic epidermal cells release a balance of cytokines that potentiate T-cell activation. Because normal epidermal cells do not potentiate T-cell activation in this system, these findings demonstrate a mechanism by which the epidermis may non-specifically potentiate and perpetuate T-cell activation in psoriatic lesions.