BK virus replication in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

BK virus (BKV) is an important cause of renal dysfunction in kidney transplant (KTX) recipients. Immunosuppression intensity is a major risk factor for BKV replication in these patients. The prevalence of BKV replication in immunosuppressed patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) without transplant is not known.

METHODS

Consecutive patients (n = 37) with a diagnosis of GPA (n = 25) or MPA (n = 12) without history of KTX were evaluated for plasma BKV replication by quantitative PCR (group A). Descriptive data were collected. BKV replication in this nontransplant immunosuppressed vasculitis cohort was compared with a historical cohort of vasculitis KTX recipients (group B).

RESULTS

Group A patients had mean disease duration of 75 months. Mean age was 57 years and 54% were female. Mean time from vasculitis onset to BKV testing was 36 months, and 19/37 patients were tested within 24 months of induction therapy. At the time of BKV testing, 73% were on prednisone (P) with azathioprine, mycophenolate mofetil (MMF), methotrexate or leflunomide. None of the nontransplanted vasculitis patients had detectable plasma BKV. Among 35 patients in group B, 16 were tested for BKV; 5/16 (31%) had detectable virus in plasma at a mean of 6 months after TX (p = 0.002). Most (94%) were on maintenance therapy with MMF, P and tacrolimus.

CONCLUSION

Immunosuppressed patients with GPA/MPA without KTX had no evidence of plasma BKV. However, BKV was common in GPA/MPA patients after KTX, suggesting that replication may be related to differences in immunosuppression, alloimmune activation or differences in host defense mechanisms.

Intracortical bone remodeling variation shows strong genetic effects

Intracortical microstructure influences crack propagation and arrest within bone cortex. Genetic variation in intracortical remodeling may contribute to mechanical integrity and, therefore, fracture risk. Our aim was to determine the degree to which normal population-level variation in intracortical microstructure is due to genetic variation. We examined right femurs from 101 baboons (74 females, 27 males; aged 7-33 years) from a single, extended pedigree to determine osteon number, osteon area (On.Ar), haversian canal area, osteon population density, percent osteonal bone (%On.B), wall thickness (W.Th), and cortical porosity (Ct.Po). Through evaluation of the covariance in intracortical properties between pairs of relatives, we quantified the contribution of additive genetic effects (heritability [h (2)]) to variation in these traits using a variance decomposition approach. Significant age and sex effects account for 9 % (Ct.Po) to 21 % (W.Th) of intracortical microstructural variation. After accounting for age and sex, significant genetic effects are evident for On.Ar (h (2) = 0.79, p = 0.002), %On.B (h (2) = 0.82, p = 0.003), and W.Th (h (2) = 0.61, p = 0.013), indicating that 61-82 % of the residual variation (after accounting for age and sex effects) is due to additive genetic effects. This corresponds to 48-75 % of the total phenotypic variance. Our results demonstrate that normal, population-level variation in cortical microstructure is significantly influenced by genes. As a critical mediator of crack behavior in bone cortex, intracortical microstructural variation provides another mechanism through which genetic variation may affect fracture risk.

Surface Structure of Silica Glasses by Molecular Dynamics Simulations

Molecular dynamics computer simulations were used to study surfaces of pure silica glass. The potentials used here were those previously established to model bulk silica and have been extended to study surface relaxation in a perfect vacuum. A large number of surfaces were made using different starting configurations; system sizes, and cooling procedures. Following “fracture”, many broken bonds rearranged in response to the changes in the net forces in the surface region. After this reconstruction, the simulations showed the expected general features observed experimentally, such as a prevalence of oxygen atoms at the outermost surface, non-bridging oxygens, and strained siloxane bonds. Three fold silicons (similar to e’ centers) were initially present in the “fractured” surfaces but most often were incorporated into the network tetrahedrally after reconstruction. Other defects produced during the reconstruction were five coordinated silicons and more importantly, edge sharing tetrahedra, forming the strained siloxane bonds. Bond angles and bond lengths for each defect were determined, showing good agreement with previously published results as well as providing new information. Finally, estimations for silanol concentrations were made which compare well with experimentally determined coverages. The computer simulation technique used here adequately reproduces many of the structural and dynamic characteristics of silica glass surfaces.

Antifungal prophylaxis with voriconazole or itraconazole in lung transplant recipients: hepatotoxicity and effectiveness

Invasive fungal infections (IFI) are common after lung transplantation and there are limited data for the use of antifungal prophylaxis in these patients. Our aim was to compare the safety and describe the effectiveness of universal prophylaxis with two azole regimens in lung transplant recipients. This is a retrospective study in lung transplant recipients from July 2003 to July 2006 who received antifungal prophylaxis with itraconazole or voriconazole plus inhaled amphotericin B to compare the incidence of hepatotoxicity. Secondary outcomes include describing the incidence of IFI, clinical outcomes after IFI and mortality. Sixty-seven consecutive lung transplants received antifungal prophylaxis, 32 itraconazole and 35 voriconazole and inhaled amphotericin B. There were no significant differences between groups in the acute physiology and chronic health evaluation (APACHE) score at the time of transplantation, demographic characteristics, comorbidities and concomitant use of hepatotoxic medications. Hepatotoxicity occurred in 12 patients receiving voriconazole and inhaled amphotericin B and in no patients receiving itraconazole (p < 0.001). There was no significant difference between groups with regard to the percentage of transplants with IFI, but one case of zygomycosis occurred in a transplant treated with voriconazole. Voriconazole prophylaxis after lung transplantation was associated with a higher incidence of hepatotoxicity and similar clinical effectiveness when compared to itraconazole.

Gene set enrichment analysis to evaluate expression of autoantigens in lung cancer

e22048

Background: There is a well-established association between certain autoimmune diseases and the development of specific malignancies. It has been demonstrated that myositis-specific autoantigens are expressed at higher levels in tumors associated with myositis compared to normal tissue, suggesting that immune responses to antigens expressed in nascent tumors may contribute to the autoimmune process. Whether this observation is a general feature of autoantigen expression in tumor tissue, and whether the relative expression of these antigens is enriched in relation to the rest of the tumor transcriptome is currently unknown. Methods: Tumor tissue from ten lung cancer biopsies (adenocarcinoma (4), carcinoid (4), and squamous cell carcinoma (2)) and normal lung from the same patients were obtained. Total RNA was extracted and hybridized to Illumina Sentrix BeadChips. Hiearchical clustering was used to visualize the expression levels of 146 known autoantigens. Gene Set Enrichment Analysis was performed using 20 disease-specific autoantigen gene sets and 1892 gene sets from the Molecular Signatures Database. Protein levels of selected autoantigens were assessed by immunoblotting detergent tissue lysates. Results: Single-linkage hierarchical clustering analysis reveals groups of autoantigens that are differentially expressed between normal lung tissue, carcinoid tumors, and adenocarcinomas. Adenocarcinoma tumor samples were significantly enriched for myositis (nominal p-value <0.001, false discovery rate (FDR) q-value 0.009) and SLE autoantigens (p-value 0.004, FDR 0.029). Scleroderma autoantigens were enriched in carcinoid tumors (p-value 0.003, FDR 0.053). Increased protein expression of the autoantigens Mi-2 and topoisomerase-1 in carcinoid tumors was confirmed by immunoblotting. Conclusions: This study reveals that autoantigens targeted in several autoimmune diseases are both transcribed and expressed at high levels in malignancies known to associate with those disorders. While autoantigens comprise only a small fraction of the total transcriptome, they are disproportionately expressed in tumors known to associate with autoimmunity, supporting the hyporthesis that autoimmunity to these proteins may arise via nascent anti-tumor responses.

No significant financial relationships to disclose.

Osteopenia and osteoporosis in adult baboons (Papio hamadryas)

BACKGROUND

Little is known about the degree to which baboons, an important animal model in skeletal research, spontaneously experience age-related osteopenia and osteoporosis.

METHODS

We measured bone mineral density (BMD) in 667 baboons, assigned T-scores to older animals based on sex-specific young adult reference groups, and compared reproductive history in older females with low BMD to those with normal BMD.

RESULTS

Approximately 25% of older baboon females were osteopenic. No females or males were osteoporotic. Neither parity nor interbirth interval spine clearly distinguished low vs. normal BMD groups. Intersite correspondence in low BMD was highest between sites in the same region rather than sites of the same bone type.

CONCLUSION

As with humans, osteopenia is common among older females. The absence of osteoporotic animals may be due to colony maintenance resulting in truncation of the aged population and selection for healthier animals in the oldest ranges.

Clinical emergence of entecavir-resistant hepatitis B virus requires additional substitutions in virus already resistant to Lamivudine

Entecavir (ETV) exhibits potent antiviral activity in patients chronically infected with wild-type or lamivudine (3TC)-resistant (3TC(r)) hepatitis B virus (HBV). Among the patients treated in phase II ETV clinical trials, two patients for whom previous therapies had failed exhibited virologic breakthrough while on ETV. Isolates from these patients (arbitrarily designated patients A and B) were analyzed genotypically for emergent substitutions in HBV reverse transcriptase (RT) and phenotypically for reduced susceptibility in cultures and in HBV polymerase assays. After 54 weeks of 3TC therapy, patient A (AI463901-A) received 0.5 mg of ETV for 52 weeks followed by a combination of ETV and 100 mg of 3TC for 89 weeks. Viral rebound occurred at 133 weeks after ETV was started. The 3TC(r) RT substitutions rtV173L, rtL180M, and rtM204V were present at study entry, and the additional substitutions rtI169T and rtM250V emerged during ETV-3TC combination treatment. Reduced ETV susceptibility in vitro required the rtM250V substitution in addition to the 3TC(r) substitutions. For liver transplant patient B (AI463015-B), previous famciclovir, ganciclovir, foscarnet, and 3TC therapies had failed, and RT changes rtS78S/T, rtV173L, rtL180M, rtT184S, and rtM204V were present at study entry. Viral rebound occurred after 76 weeks of therapy with ETV at 1.0 mg, with the emergence of rtT184G, rtI169T, and rtS202I substitutions within the preexisting 3TC(r) background. Reduced susceptibility in vitro was highest when both the rtT184G and the rtS202I changes were combined with the 3TC(r) substitutions. In summary, infrequent ETV resistance can emerge during prolonged therapy, with selection of additional RT substitutions within a 3TC(r) HBV background, leading to reduced ETV susceptibility and treatment failure.

Polymorphisms of Helicobacter pylori HP0638 reflect geographic origin and correlate with cagA status

Since the associations between Helicobacter pylori genotype and disease differ in Asia and the West, we investigated the correlation between HP0638, encoding an outer membrane protein, and potential markers of virulence (cagA, vacA, and iceA). For 109 strains from nine countries, the status of cagA, vacA, and iceA was determined by PCR and/or a line probe assay. We also studied 18 strains from 8 patients (parents and 6 daughters) from a Dutch family and paired strains collected on average 8 years apart from 11 patients. When the HP0638 signal sequences were amplified by PCR and DNA sequence determinations were performed, 89 (96%) of 93 cagA-positive strains had HP0638 in frame, versus none (0%) of 16 cagA-negative strains (P < 0.001). Among strains in which HP0638 was in frame, a six-CT dinucleotide repeat pattern was dominant in Western countries (23 of 33 strains [70%]), while a pattern of three CT repeats with another CT after four T's (3 + 1-CT-repeat pattern) was dominant in East Asia (31 of 46 strains [67%]); however, specific CT repeat patterns did not correlate with clinical outcome. HP0638 phylogenetic trees also showed geographic characters. The HP0638 frame status and CT dinucleotide repeat patterns were identical for 9 of 11 pairs of strains obtained on average 8 years apart from individuals and the 15 strains obtained from the mother and all six daughters. Thus, HP0638 frame status and cagA status are strongly correlated. The CT dinucleotide repeat pattern in the putative HP0638 signal sequence has geographic characters and appears stable in particular patients and families over a period of years. Analysis of HP0638 CT polymorphisms may serve as a new typing system to discriminate H. pylori isolates for epidemiological purposes.

Pulmonary artery systolic pressures estimated by echocardiogram vs cardiac catheterization in patients awaiting lung transplantation

BACKGROUND

At many lung transplant centers, right heart catheterization and transthoracic echocardiogram are part of the routine pre-transplant evaluation to measure pulmonary pressures. Because decisions regarding single vs bilateral lung transplant procedures and the need for cardiopulmonary bypass are often made based on pulmonary artery systolic pressures, we sought to examine the relationship between estimated and measured pulmonary artery systolic pressures using echocardiogram and catheterization, respectively.

METHODS

We retrospectively reviewed all patients in our program who had measured pulmonary hypertension (n = 57). Patients with both echocardiogram-estimated and catheterization-measured pulmonary artery systolic pressures performed within 2 weeks of each other were included (n = 19). We analyzed results for correlation and linear regression in the entire group and in the patients with primary pulmonary hypertension (n = 8) and pulmonary fibrosis (n = 8).

RESULTS

In patients with primary pulmonary hypertension, pulmonary artery systolic pressure was 94 +/- 27 and 95 +/- 15 mm Hg by echocardiogram and catheterization, respectively, with r(2) = 0.11; in patients with pulmonary fibrosis, 57 +/- 23 and 58 +/- 12 mm Hg with r(2) = 0.22; and in the whole group, 76 +/- 29 and 75 +/- 23 mm Hg with r(2) = 0.50. Thirty-two additional patients had mean pulmonary artery systolic pressure = 48 +/- 16 mm Hg by catheterization but either had no evidence of tricuspid regurgitation by echocardiogram (n = 22) or the pulmonary artery systolic pressure could not be measured (n = 10).

CONCLUSIONS

In patients with pulmonary hypertension awaiting transplant, pulmonary artery systolic pressures estimated by echocardiogram correspond but do not serve as an accurate predictive model of pulmonary artery systolic pressures measured by catheterization. Technical limitations of the echocardiogram in this patient population often preclude estimating pulmonary artery systolic pressure.

New approaches to treatment in systemic vasculitis: biological therapies

Although the effectiveness of biological agents in systemic vasculitis is unproven, their introduction heralds a new era of vasculitis treatment. These agents offer the promise of targeted immunotherapies; the possibility of greater efficacy (and fewer side-effects) than conventional vasculitis treatments; and the potential to provide novel insights into the pathophysiology of these diseases-insights that may be gained only by using these agents in humans. Challenges to the investigation of these therapies in the systemic vasculitides exist, but important basic and clinical investigations are already in progress. We review the major issues facing the investigation of biological agents in vasculitis; examine the rationale for believing that biological strategies in vasculitis will be efficacious; identify several candidate targets for biological approaches; and discuss the results to date of early studies. The potential biological targets discussed include cytokines such as tumour necrosis factor; interleukins-1, -6, and -12; interferon-gamma; the co-stimulatory molecules B7-1 and B7-2; and others.

Subscapularis Tendon Tear: Primary and Associated Signs on MRI

PURPOSE

The purpose of this work was to investigate signs of subscapularis tendon tear on MRI.

METHOD

Preoperative written interpretations of high field (n = 9) and low field (n = 7) MRI of 16 patients with tears confirmed at surgery or arthroscopy were reviewed, followed by retrospective review of these studies.

RESULTS

A preoperative diagnosis of subscapularis tear was made in five (31%) cases. On retrospective review, primary signs of tear were present in 15 (94%) cases and in two-thirds were limited to the cranial third of the tendon. Supraspinatus tears were present in 69% of cases. Associated findings included medial dislocation (n = 4) or subluxation (n = 3) of biceps tendon, biceps tendinopathy (n = 2), superior labral tear (n = 5), and effusions of superior subscapularis recess (n = 6), subcoracoid bursa (n = 2), or both (n = 5). One or more associated signs were present in 94% of cases.

CONCLUSION

Subscapularis tear is frequently missed on MRI. Recognizing that primary signs of tear may be limited to the cranial third of the subscapularis tendon and identifying associated signs should facilitate diagnosis.

Posttransplant lymphoproliferative disorders in lung transplant recipients: clinical experience at a single center

OBJECTIVES

Posttransplant lymphoproliferative disorders (PTLD) can be a significant cause of morbidity in lung transplant (LT) recipients. Risk factors include Epstein-Barr virus (EBV) infection, particularly primary infection, and immunosuppression. This article updates the incidence and presentation of PTLD at our lung transplant program.

METHODS

We retrospectively reviewed the immunosuppression, EBV serology, and cases of PTLD among 129 lung transplant recipients at risk who survived > 1 month.

RESULTS

There were two cases of PTLD among 129 LT patients, 2/129 (1.6%). One of these patients was among the 6 EBV seroconverters, 1/6 (16.7%), and had a typical presentation of PTLD in the allograft resulting in dissemination and death. The second case of PTLD developed in an EBV seropositive recipient who presented 33 months following LT with isolated colonic involvement. He subsequently died from chronic rejection.

CONCLUSIONS

The incidence of PTLD in a LT program with a large EBV seropositive population is low, 1.6%. The presentation of PTLD in LT recipients is variable and may present typically with allograft involvement in the first year following transplantation, or late with isolated, extrapulmonic involvement.

Bronchiolitis Obliterans

Bronchiolitis obliterans (BO) is a fibrotic lung disease involving the small conducting airways. BO may be classified by etiology and underlying disease or, more commonly, by histopathological pattern. The two major histopathological categories are (1) BO organizing pneumonia (BOOP) and proliferative bronchiolitis and (2) constrictive bronchiolitis. The former is often idiopathic in nature and may also be associated with connective tissue diseases and inhalation injury. Characteristic findings on chest imaging include alveolar infiltrates and ground glass opacities and pulmonary function tests (PFTs) usually reveal restrictive dysfunction. Constrictive bronchiolitis is associated with organ transplantation, infections, connective tissue diseases, inhalation injury, and drugs and may also have an idiopathic origin. The radiographic characteristic is a mosaic pattern on high-resolution computed tomography (HRCT) and PFTs most often reveal obstructive dysfunction. This article will attempt to review constrictive BO, including histopathology, clinical presentation, radiographic appearance, and physiological findings, for both idiopathic diseases, as well as specific clinical-associated entities.

A low incidence of posttransplant lymphoproliferative disorder in 109 lung transplant recipients

STUDY OBJECTIVES

The incidence of posttransplant lymphoproliferative disorder (PTLD) has been reported to range from 6.4 to 20% in lung transplant (LT) recipients. Postulated contributing factors include Epstein-Barr virus (EBV) infection and the use of immunosuppression, particularly muromonab-CD3 (OKT3)(Orthoclone OKT-3; Ortho Biotech; Raritan, NJ). We sought to examine these PTLD risk factors in 109 LT recipients at our institution who survived > 1 month.

DESIGN

Retrospective review of EBV serology of all LT recipients at our institution. Our standard transplant protocol includes OKT3 for induction and refractory rejection, as well as lifelong acyclovir for herpes prophylaxis. We do not perform EBV donor-recipient matching.

SETTING

A university-based LT center.

RESULTS

We found that 5 of 109 patients were serologically negative for EBV prior to lung transplantation, and all of these patients converted following lung transplantation. The mean time to conversion was 151 days (range, 11 to 365 days). One fatal case of PTLD was documented in an EBV seroconverter (one of five patients) 12 weeks status posttransplantation for lymphangioleiomyomatosis. One nonfatal extrathoracic PTLD was documented in a seropositive patient (1 of 104 patients) 33 months posttransplantation.

CONCLUSIONS

We conclude the following: (1) PTLD in LT recipients may have a lower incidence (2 of 109 patients; 1.8%) than previously reported, despite an aggressive immunosuppressive regimen; and (2) the incidence of PTLD is higher in patients with primary EBV infection (20% vs 1%).

Identification, display, and use of symmetry elements in atomic and electronic structure models

Crystallographic symmetry plays an important role in structure determination from diffraction or scattering data, in spectroscopy and in simulations. It is convenient and insightful to integrate the display and use of such symmetry data with data analysis and modeling methods. We outline the integration of a suite of crystallographic algorithms, closely coupled with interactive graphical displays. These include techniques for identifying the unit cell of a solid, for automatically determining space and point group symmetries, for generalized displays of symmetry elements overlaid on structural models, and for construction, editing, and transformation of models subject to symmetry constraints. In addition, electron densities derived from periodic density functional calculations can be symmetrized and displayed with the corresponding symmetry elements. Applications of these various capabilities in crystallographic research are illustrated by topical examples.

Use of balloon-expandable metallic stents in the management of bronchial stenosis and bronchomalacia after lung transplantation

STUDY OBJECTIVES

Bronchial stenosis (BS) and bronchomalacia (BM) are often associated with lung allograft rejection or infection in lung transplant (LT) recipients. We reviewed our experience using balloon-expandable metallic (Palmaz) stents in the management of BS and BM in LT.

DESIGN

Retrospective review of cases.

PATIENTS

LT recipients with bronchoscopic and spirometric evidence of BS and BM.

INTERVENTIONS

Serial balloon dilation was performed for BS. Stent placement was done for refractory or recurrent BS, or persistent focal BM.

RESULTS

Twelve of 129 LT bronchial anastomoses at risk (9.3%) had complications, which included 11 BS and 5 BM. Four BS were accompanied by BM either concurrently or subsequently. The only isolated BM was associated with acute rejection and resolved after appropriate medical therapy. Balloon dilations alone were successful in relieving BS in three cases. Seven patients received a total of 11 stents. Stents were placed under conscious sedation using a flexible bronchoscope. Five of the seven patients had spirometric improvements after stent placements. One patient had no spirometric improvement, and another died before a follow-up study was done. There were no complications during stent placements. However, complications after stent placements included partial dehiscence of the stent from the bronchial wall, stent migration, partial obstruction of a segmental bronchial orifice by a stent in the main bronchus, and longitudinal stent collapse. One stent was successfully removed using a flexible bronchoscope in the endoscopy suite, and two others were removed by rigid bronchoscopy in the operating room.

CONCLUSIONS

Endobronchial placement of the Palmaz stent in LT recipients is relatively easy, and it can be removed if needed. However, because there are significant potential complications, the future use of this stent as an airway prosthesis in LT remains unclear.

Chronic fatigue syndrome and seasonal affective disorder: comorbidity, diagnostic overlap, and implications for treatment

This study aimed to determine symptom patterns in patients with chronic fatigue syndrome (CFS), in summer and winter. Comparison data for patients with seasonal affective disorder (SAD) were used to evaluate seasonal variation in mood and behavior, atypical neurovegetative symptoms characteristic of SAD, and somatic symptoms characteristic of CFS. Rating scale questionnaires were mailed to patients previously diagnosed with CFS. Instruments included the Personal Inventory for Depression and SAD (PIDS) and the Systematic Assessment for Treatment Emergent Effects (SAFTEE), which catalogs the current severity of a wide range of somatic, behavioral, and affective symptoms. Data sets from 110 CFS patients matched across seasons were entered into the analysis. Symptoms that conform with the Centers for Disease Control and Prevention (CDC) case definition of CFS were rated as moderate to very severe during the winter months by varying proportions of patients (from 43% for lymph node pain or enlargement, to 79% for muscle, joint, or bone pain). Fatigue was reported by 92%. Prominent affective symptoms included irritability (55%), depressed mood (52%), and anxiety (51%). Retrospective monthly ratings of mood, social activity, energy, sleep duration, amount eaten, and weight change showed a coherent pattern of winter worsening. Of patients with consistent summer and winter ratings (n = 73), 37% showed high global seasonality scores (GSS) > or = 10. About half this group reported symptoms indicative of major depressive disorder, which was strongly associated with high seasonality. Hierarchical cluster analysis of wintertime symptoms revealed 2 distinct clinical profiles among CFS patients: (a) those with high seasonality, for whom depressed mood clustered with atypical neurovegetative symptoms of hypersomnia and hyperphagia, as is seen in SAD; and (b) those with low seasonality, who showed a primary clustering of classic CFS symptoms (fatigue, aches, cognitive disturbance), with depressed mood most closely associated with irritability, insomnia, and anxiety. It appears that a subgroup of patients with CFS shows seasonal variation in symptoms resembling those of SAD, with winter exacerbation. Light therapy may provide patients with CFS an effective treatment alternative or adjunct to antidepressant drugs.

Long bone surface osteomas: imaging features that may help avoid unnecessary biopsies

OBJECTIVE

Our purpose is to show that a combination of imaging techniques and periodic radiologic follow-up offers an alternative to biopsy in certain patients with long bone surface osteomas.

CONCLUSION

Asymptomatic lesions that are consistent with osteoma on a combination of imaging studies can be followed up clinically and radiographically, allowing patients to avoid unnecessary biopsies.

Effect of nitric oxide synthase inhibitor on diaphragmatic function after resistive loading

We studied the effect of a nitric oxide synthase inhibitor, Nomega-Nitro-L-arginine-methyl-ester (L-NAME), on in vitro diphragmatic function both at rest (control) or after inspiratory resistive loading (IRL). Sprague-Dawley rats were anesthetized, instrumented, and then the following experimental groups: (1) controls; (2) L-NAME (100 mg/kg/body weight intravenously alone); (3) IRL alone; and (4) L-NAME + IRL. The IRL protocol consisted of applying a variable resistor to the inspiratory limb of a two-way valve at 70% of maximal airway pressure until apnea. After the experiment, the animals were sacrificed and diaphragmatic strips were obtained for activity of constitutive nitric oxide synthase (cNOS) and measurements of in vitro contractile properties: tetanic (Po) and twitch tensions (Pt). cNOS activity was significantly decreased in the L-NAME and L-NAME + IRL groups (P < or = 0.05) as compared with control and IRL groups. L-NAME alone did not affect Po or Pt. However, in both IRL groups, with and without was a significant decrease in Po and Pt. This reduction was comparable in both groups. In summary, our data showed that L-NAME resulted in a significant decrease cNOS activity, but in vitro contractility was impaired.

Tuberculosis of contralateral costo-transverse joints

We present a case of multifocal tuberculosis of contralateral costo-transverse joints. Even in countries where tuberculosis is common, extrapulmonary multifocal infection is uncommon. Furthermore, a bilateral, symmetric distribution is distinctly unusual. The index of suspicion for tuberculosis should increase when the patient is from a country where tuberculosis is endemic or when a history of AIDS is present.

Knee and shoulder fractures: association of fracture detection and marrow edema on MR images with mechanism of injury

PURPOSE

To assess the value of magnetic resonance (MR) imaging for enabling the classification of fracture mechanisms and to compare marrow edema caused by compressive forces with that caused by tensile forces.

MATERIALS AND METHODS

In 62 knees or shoulders, 78 fractures were identified prospectively on MR images or plain radiographs; compressive or tensile forces were determined retrospectively to have caused impaction or distraction fractures, respectively. Edema was measured on T1-weighted images. Frequencies of fracture detection on MR images or plain radiographs were compared.

RESULTS

Forty-nine (63%) and 29 (37%) fractures were attributed to compressive and tensile forces, respectively. Edema measured 31 mm +/- 10 in impaction fractures and 2.5 mm +/- 2.4 in distraction fractures (P < .001). MR images and plain radiographs of 63 fractures were compared. On MR images, distraction fractures, including four of seven Segond fractures, were missed more often than impaction fractures (P < .008). Fractures overlooked on MR images were associated with less edema (P < .003).

CONCLUSION

On MR images, impaction fractures demonstrate prominent marrow edema, and distraction fractures demonstrate minimal edema. Impaction fractures are more often missed on plain radiographs, and distraction fractures are more often missed on MR images. Segond fractures should be suspected if MR images show lateral capsular ligamentous injury in the knee; in these cases, evaluation with plain radiography is warranted.

Systemic availability of itraconazole in lung transplantation

Systemic availability of itraconazole in lung transplantation was evaluated by serially measuring the bioactivity of itraconazole in lung transplant patients who received itraconazole for prophylaxis (n = 12) or therapy (n = 5). These patients also received concomitant antacid and H2 blocker therapy. In patients receiving itraconazole at 200 and 400 mg/day, the median concentrations in serum were 0.5 microgram/ml (range, < 0.05 to 2.7) and 3.5 micrograms/ml (< 0.5 to 14), respectively. The concentration following administration of 400 mg/day was > 2.5 micrograms/ml in 56% of samples, while only 4% of samples from patients who were administered 200 mg/day had levels over 2.5 micrograms/ml. This study documents that itraconazole can be absorbed in patients receiving concomitant antacid and H2 blocker therapy. However, the reduced and variable absorption suggests the importance of confirming drug delivery by measurement of concentrations in serum.

Bioavailability of medication after laparoscopic cholecystectomy

Bioavailability of medication after laparoscopic cholecystectomy has not been studied previously. There is concern about the ability of patients to tolerate oral medication postoperatively and the optimal timing of hospital discharge. In this study, each subject received 20 mg/kg acetaminophen (po) preoperatively, with a repeat dose at 6 (group 1), 12 (group 2), or 24 h (group 3) postoperatively. Serum levels were obtained 40 and 90 min after each ingestion. Bioavailability of medication was significantly decreased (p < 0.01) 6 h (group 1) and 12 h (group 2) postoperatively. Bioavailability returned to baseline by 24 h after laparoscopic cholecystectomy (group 3). This study indicates that oral medication should be used judiciously during the first 12 h after laparoscopic surgery.

Bioavailability of medication delivered via nasogastric tube is decreased in the immediate postoperative period

BACKGROUND

A study was performed to determine bioavailability of medication delivered via nasogastric tube in patients after abdominal surgery.

METHODS

Acetaminophen (20 mg/kg) was administered to each patient per os at least 48 hours prior to abdominal surgery and via nasogastric tube 3 hours postoperatively. The nasogastric tube was clamped for 30 minutes after drug administration, prior to resuming suction. Serum levels of acetaminophen were measured 0, 40, and 90 minutes after each dose.

RESULTS

Acetaminophen levels were significantly lower (P < 0.001) when the drug was administered via nasogastric tube postoperatively.

CONCLUSIONS

Decreased bioavailability of medications delivered via nasogastric tube may have important clinical implications and should be taken into consideration during the postoperative period.

Enhanced resistance to nuclease degradation of nucleic acids complexed to asialoglycoprotein-polylysine carriers

We have previously shown targeting of DNA to hepatocytes using an asialoorosomucoid-polylysine (AsOR-PL) carrier system. The AsOR-PL conjugate condenses DNA and facilitates entry via specific receptor-ligand interactions. In these studies, our objective was to determine if AsOR-PL conjugates protect bound DNA from nuclease attack. Double-stranded plasmid or single-stranded oligonucleotide DNA, alone or bound to conjugate, was incubated under conditions mimicking those encountered during in vitro and in vivo transfections. The results showed that complexed DNA was effectively protected from degradation by serum nucleases. Degradation of single-stranded oligonucleotides was inhibited 3- to 6-fold in serum during 5 hours of incubation. For complexed plasmids, greater than 90% remained full-length during 1.5 and 3 hour incubations in serum or culture medium containing 10% serum, respectively. Uncomplexed plasmid was completely degraded after 15 minutes in serum or 60 minutes in medium. In cell lysates, the conjugate was not effective in inhibiting endonuclease activity; plasmids were readily converted from supercoiled to open circular and linear forms. However, the resultant nicked forms were substantially protected from further degradation during one hour of incubation compared to plasmid alone. Under all conditions complexed DNA did not readily dissociate from the conjugate. Overall, for both single and double-stranded DNA, AsOR-PL conjugates conferred substantial protection from nuclease degradation.

Development of intracranial tuberculomas while receiving therapy for pulmonary tuberculosis [corrected]

Development of tuberculomas on adequate tuberculosis therapy is an uncommon event. This case report describes a patient who developed multiple intracranial tuberculomas while receiving adequate supervised outpatient therapy for sensitive pulmonary tuberculosis who was documented to have no intracranial lesions prior to initiation of treatment.

Expression and alternative splicing of the deleted in colorectal cancer (DCC) gene in normal and malignant tissues

The DCC (deleted in colorectal cancer) gene was identified because it is affected by somatic mutations in colorectal tumors, including allelic losses in greater than 70% of cancers and localized mutations in a subset of cases. The DCC gene also may be inactivated in other tumor types, including cancers of the pancreas, stomach, breast, prostate, and brain, as well as some leukemias. We have characterized DCC complementary DNAs obtained from human fetal brain tissues and IMR32 human neuroblastoma cells. Based on the fetal brain complementary DNA sequence, the predicted transmembrane DCC protein product has 1447 amino acids. The extracellular domain of about 1100 amino acids has four immunoglobulin-like domains and six fibronectin type III-like domains; the 325-amino acid cytoplasmic domain does not show similarity to previously characterized proteins. Comparison of DCC complementary DNAs from IMR32 cells to those from fetal brain identified two potential alternative splice sites. Studies of adult mouse tissues revealed that DCC transcripts were present at very low levels in all tissues studied, and alternative splicing of DCC transcripts was seen in some tissues. Immunoblotting and immunoprecipitation studies with DCC-specific antisera identified protein species with molecular weights of approximately 175,000-190,000 in some rodent tissues and human tumor cell lines. DCC protein expression was highest in brain tissues and neural crest-derived cell lines and markedly reduced or absent in the majority of cancer cell lines studied. Treatment of DCC-expressing cells with tunicamycin decreased the apparent molecular weight of the immunoreactive proteins, establishing that DCC is a glycoprotein. The studies presented here demonstrate that the DCC gene encodes several related glycoprotein species that are likely to be expressed at very low levels in many normal adult tissues. Furthermore, the absence of DCC expression in some of the cancer cell lines studied may result from genetic inactivation of DCC.

Medium term functional results of single-lung transplantation for endstage obstructive lung disease

Controversy has surrounded the use of single-lung transplantation (SLT) for the treatment of endstage obstructive lung disease. In recent years, several transplant centers have performed SLT for such indications. In this report, we describe functional results in patients undergoing SLT for obstructive lung disease, twenty-two followed over one year and 10 over two years. Data include pulmonary function testing, gas exchange, quantitative ventilation and perfusion to the lung graft, and results of symptom-limited graded cycle exercise testing after SLT. Our results show improvement in obstructive dysfunction FEV1 0.49 +/- 0.13 L (16 +/- 4% predicted) pre-SLT to 1.71 +/- 0.43 L (57 +/- 12% predicted) 3 mo after SLT, FEV1/FVC 0.30 +/- 0.07 pre-SLT to 0.75 +/- 0.09 3 mo after SLT, and improvement in arterial oxygenation, PaO2 58 +/- 10 mm Hg pre SLT to PaO2 86 +/- 13 mm Hg 3 mo post-SLT. In addition, these improvements were sustained up to 1 to 2 yr post-SLT. The majority of ventilation and perfusion go to the new lung graft. After SLT, patients have reduced maximum oxygen consumption (VO2max 40 to 60% predicted) but do not have ventilatory limitation to exercise and can carry out daily activities without compromise. We conclude that SLT is a viable medium-term therapeutic option for endstage obstructive lung disease. The long-term future of this technique remains to be determined.

Effects of hyperoxia on rat diaphragm function

The association of oxygen radical generation with impaired diaphragm performance has previously been reported after inspiratory resistive loading (IRL). We hypothesized that exposure of rats to normobaric hyperoxia (O2) could produce impaired diaphragm function because of free radical production. Sprague-Dawley rats were divided into four groups: 1) room air (control), 2) > 95% O2 for 24 h, 3) > 95% O2 for 48 h, and 4) > 95% O2 for 60 h. Each group was studied at rest after the O2 exposure and then after IRL. During IRL, the animals breathed through an inspiratory resistor until they were unable to sustain > 70% of the maximum airway pressure. Diaphragm samples were obtained for analysis of glutathione (GSH) and glutathione disulfide (GSSG) concentrations. In vitro isometric contractile properties were also determined, including maximal tetanic tension (Po) and maximal twitch tension (Pt), in GSSG content and in GSSG-to-GSH ratios. Hyperoxia for > 48 h resulted in significant decreases in Po and Pt and an increase in GSSG content and in GSSG-to-GSH ratios compared with other groups. Those same animals subjected to IRL showed a further decrease in Po and Pt. These data suggest that free radical generation may occur in the diaphragm during a hyperoxia exposure associated with activation of the GSH redox cycle and impairment of diaphragm function.

Buthionine sulfoximine treatment impairs rat diaphragm function

Activation of the glutathione (GSH) redox cycle with production of glutathione disulfide (GSSG) has been shown to occur in the diaphragm during inspiratory resistive loading (RB). Buthionine sulfoximine (BSO) lowers tissue GSH by irreversibly inhibiting the rate-limiting synthesis enzyme gamma-glutamylcysteine synthetase. We investigated the effects of BSO on rat diaphragm function, both at rest and after a period of RB. Rats in the RB groups underwent inspiratory RB until they were unable to sustain 70% of their maximal airway pressure. A portion of the diaphragm was analyzed for GSH and GSSG levels, and measurements of in vitro contractile properties included contraction times, maximal tetanic tension (Po), maximal twitch tension (Pt), and force frequency curves. BSO treatment produced a profound depletion of diaphragmatic GSH. Neither BSO nor RB alone significantly altered diaphragm contractile properties at this load of RB. But, in BSO-RB rats, there was a significant decrease in Pt, Po, and tetanic tension at all frequencies of stimulation compared with those in other groups. These data reveal that animals treated with BSO followed by inspiratory resistive loading exhibit marked diaphragm impairment, suggesting that GSH may play an important role in protecting the diaphragm from the stress induced by this resistive breathing protocol.

Single lung transplantation in patients with systemic disease

OBJECTIVE

To report functional results and survival in patients undergoing single lung transplantation (SLT) for pulmonary involvement associated with systemic disease or prior malignancy, criteria traditionally considered contraindications to SLT.

DESIGN

Case series.

SETTING

The University of Texas Health Science Center at San Antonio.

PATIENTS

Nine patients who have undergone SLT for end-stage lung disease: four patients with sarcoidosis; two patients with limited scleroderma; and three patients with prior malignancies (two with prior lymphoma and bleomycin-induced pulmonary fibrosis and one who received two bone marrow transplants for acute lymphocytic leukemia and subsequently developed chemotherapy-induced pulmonary fibrosis).

MEASUREMENTS

Pulmonary function testing, exercise oximetry, quantitative ventilation-perfusion lung scanning. Actuarial survival.

RESULTS

All patients had marked improvement in pulmonary function, exercise oximetry, and quantitative ventilation perfusion to the SLT. One patient with scleroderma died 90 days postoperatively from Pseudomonas pneumonia with a sepsis syndrome. One patient with sarcoidosis died 150 days postoperatively from disseminated aspergillosis. At autopsy, there was no evidence of recurrent fibrosis or sarcoidosis in the transplanted lungs in either of these two patients. The seven surviving patients have returned to work or school and are conducting all activities of daily living without pulmonary disability. The 1- and 2-year actuarial survival rates in these nine patients is 68.6 percent as compared with the 1- and 2-year actuarial survival rates of 66.3 percent and 55.8 percent in the remainder of our SLT group as a whole (n = 49). Despite pharmacologic immunosuppression, there is no evidence of recurrent malignancy in the 3 patients with prior malignancies.

CONCLUSIONS

We conclude that carefully selected patients with end-stage lung involvement related to systemic disease or chemotherapy-induced fibrosis may benefit from SLT.

Use of the flow-volume loop in the diagnosis of bronchial stenosis after single lung transplantation

Bronchial complications, including stricture, stenosis, and/or anastomotic dehiscence, are a major cause of morbidity following single lung transplantation. This report describes a 19-year-old man with a diagnosis of end-stage pulmonary fibrosis secondary to prior chemotherapy for non-Hodgkins lymphoma who underwent single lung transplantation. The immunosuppressive regimen included cyclosporine, azathioprine, and methylprednisolone sodium succinate (Solu-Medrol) intravenously for six doses during the first 3 days postoperatively followed by oral prednisone. Sixteen weeks following transplantation, the patient complained of dyspnea. Spirometry revealed a decrease in FEF25-75 and the flow-volume curve demonstrated a bioconcave appearance. The flow-volume loop showed a relatively high initial flow phase occurring over the first 2 to 3 s followed by a low-flow phase. The expiratory phase also showed the same characteristics. Bronchoscopy revealed 75 percent stenosis of the bronchial lumen to the transplanted lung. A transbronchial biopsy specimen obtained at that time was consistent with acute rejection. The patient was treated with a methylprednisolone bolus. A repeated bronchoscopy showed the persistence of stenosis distal to the anastomosis. The patient underwent several bronchoplastic balloon dilatations without complete resolution of the stenosis and a stainless steel mesh stent was placed. Repeated spirometry showed marked improvement of the FEF25-75 and normalization of the flow-volume loop. We conclude that the flow-volume loop curve is a noninvasive procedure that may help monitor the patency of the bronchial anastomoses following single lung transplantation.

Lung transplantation

Solid-organ transplantation has flourished during the last decade, with transplantation of heart and lungs becoming available to patients with end-stage cardiac or pulmonary diseases. The first lung transplant was performed in 1963 on a 58-year-old man with bronchogenic carcinoma. He survived for 18 days. During the next two decades, approximately 40 lung transplant procedures were attempted without success. These early attempts at lung transplantation were unsuccessful because of the development of lung rejection, anastomotic complications, or infection in the transplant recipients. In the early 1980s, human heart-lung transplantation was successfully performed for the treatment of pulmonary vascular disease. After this procedure, single-lung transplantation for the treatment of end-stage interstitial lung disease and obstructive lung disease was developed. More recently, the technique of double-lung transplantation has come into existence. This article reviews various aspects of lung transplantation, including immunosuppression, lung graft preservation, the various surgical techniques and types of lung transplant procedures available, recipient and donor selection criteria, and postoperative care of the transplant recipient. In addition, infectious and noninfectious complications seen in this particular patient population, including acute and chronic rejection, will be discussed.

Diethylmaleate produces diaphragmatic impairment after resistive breathing

Formation of oxygen-derived free radicals and activation of the glutathione (GSH) redox cycle has been associated with impaired rat diaphragm performance. Diethylmaleate (DEM) given intraperitoneally irreversibly conjugates with GSH, resulting in marked decreases in tissue concentrations of GSH. We have investigated the effects of acute GSH depletion by DEM on diaphragmatic function during resistive breathing (RB) in the rat. The experimental groups were 1) control, 2) DEM alone, 3) RB, and 4) DEM with RB (DEM + RB). RB was obtained by inspiratory RB until the rats were unable to sustain 70% of maximum airway opening pressure. A portion of the diaphragm was frozen for biochemical assays, and the rest of the diaphragm was prepared for measurement of in vitro contractile properties, including maximum tetanic tension, twitch tension, force-frequency curves, and contraction times. DEM treatment produced a profound depletion of GSH in the DEM and DEM + RB groups. Neither DEM nor RB alone significantly altered diaphragm contractile properties. In DEM + RB rats, however, there was a significant decrease in maximum tetanic tension, twitch tension, and tetanic tension. These data reveal that DEM produced an acute depletion of GSH in the diaphragm without impairment of the muscle in nonstressed rats. In the presence of DEM-induced GSH depletion, RB did result in marked diaphragm impairment. The depletion of GSH and the subsequent impairment in diaphragm contractility after RB suggest that GSH may play an important role in protecting the diaphragm against oxidative stress associated with RB.

Possible case of procainamide-induced intrahepatic cholestatic jaundice

OBJECTIVE

To describe a possible case of procainamide-induced intrahepatic cholestatic jaundice that was recognized six weeks after the initiation of procainamide therapy and to summarize the five previously reported cases.

CASE SUMMARY

A 77-year-old woman with a history of hypertension, insulin-dependent diabetes mellitus, temporal arteritis, and Wolff-Parkinson-White syndrome who had taken procainamide for six weeks presented to the hospital with disorientation and acute renal and hepatic dysfunction. In addition to disorientation, scleral icterus, and diffuse maculopapular rash, her physical examination was generally normal. There was no evidence of fever, nausea, vomiting, lymphadenopathy, or eosinophilia. Her liver enzyme concentrations increased significantly from baseline (beginning of procainamide therapy). Her N-acetylprocainamide (NAPA) concentration was elevated to 52 mg/L upon admission. Procainamide was discontinued and her NAPA concentration returned to within normal limits in two days. Diagnostic tests were performed to rule out active hepatitis, vasculitis, and liver malignancies. After procainamide was discontinued and prednisone treatment was started, she became more oriented and her liver enzyme concentrations slowly improved.

DISCUSSION

Only five cases of procainamide-induced liver abnormalities have been previously reported; these included granulomatous hepatitis and intrahepatic cholestasis. The mechanism for liver dysfunction is not known; however, it is proposed to be a delayed hypersensitivity reaction. Clinical hallmarks of hypersensitivity include fever, eosinophilia, rash, and lymphadenopathy; nausea and vomiting also may be present. Of the five reported cases, all experienced fever and only one experienced pruritus. No patients had eosinophilia or lymphadenopathy. Because of the temporal increase in liver enzyme concentrations after six weeks of procainamide therapy, we believe that this case represents another possible procainamide-induced hypersensitivity reaction.

CONCLUSIONS

Procainamide-induced liver dysfunction can occur from one day to six weeks after initiation of the drug and may subside one day to several weeks after discontinuation of therapy. Symptoms may include nausea, vomiting, rash, and fever. Liver enzyme concentrations are abnormal. It is important to recognize the possibility of such a reaction early so that procainamide therapy can be discontinued promptly to avoid further liver damage.

Graft position and pulmonary function after single lung transplantation for obstructive lung disease

Single lung transplantation (SLT) has become a therapeutic option for the treatment of end-stage obstructive lung disease. Between January 1989 and June 1990, there were 14 patients with end-stage obstructive lung disease who underwent SLT. Eleven of these patients were surviving at 1 year following transplantation. Three of the patients had received left-sided SLT, and eight had received right-sided SLT. In the patients receiving left-sided SLT, the native right lung radiographically appeared to compress the left lung graft. In the patients receiving right-sided SLT, the native left lung did not appear to compress the right lung graft. We hypothesized that right SLT may provide a functional advantage over left SLT for patients with obstructive lung disease. We compared pulmonary function test results before and after transplantation (approximately 3 and 12 months) and compared quantitative ventilation-perfusion lung scan results between the patients with left SLT and those with right SLT. Additionally, we compared graded-exercise test results at 3 and 12 months after transplant between the two groups. Our data revealed no statistical difference in pulmonary function test results or graded-exercise test results between the two groups, although patients undergoing right SLT showed greater increases in FEV1 and forced vital capacity than those undergoing left SLT. Quantitative ventilation and perfusion were greater to the graft in patients receiving right-sided SLT than in patients receiving left-sided SLT, most likely due to the larger size of the right lung. We conclude that there is no functional difference between patients undergoing left or right SLT for end-stage obstructive lung disease.

Exercise performance after lung transplantation

Heart-lung, double lung, and single lung transplantation have been shown to be effective in the treatment of patients with advanced cardiopulmonary disorders. An overlap in indications occurs for the different procedures, and in many situations the factors that are important in selecting the best operation for a given patient have not been clearly elucidated. To determine whether the anticipated exercise capacity should be an important consideration in the selection of the optimal procedure for a given patient, we compared exercise performance in patients who had undergone the different lung transplantation procedures in the preceding year and were otherwise well. Eleven heart-lung, six double lung, and 16 single lung recipients and 28 control subjects underwent maximal symptom-limited incremental exercise tests using a cycle ergometer. At peak exercise, transplant recipients reached maximum oxygen uptakes in the range of 40% to 60% of predicted values; no significant differences existed between the means of the different transplant groups. Ventilatory factors did not appear to limit exercise in any group. The exercise responses in the transplant subjects were characterized by reduced aerobic capacity and diminished oxygen pulse, factors indicating abnormal cardiovascular performance. Our data indicate that moderate levels of exercise can be anticipated early after heart-lung, double lung, and single lung transplantation. In the absence of substantial differences in exercise capacity, other considerations would appear to be more important in guiding the selection of the optimal lung replacement procedure for an individual patient.

Diaphragmatic function after resistive breathing in vitamin E-deficient rats

The effects of vitamin E deficiency on diaphragm function were studied at rest and after resistive breathing (RB) in Sprague-Dawley rats (wt 300-400 g). The animals were pair fed a vitamin E-deficient diet (E-def) or a matched vitamin E-sufficient diet (E-suf). Each diet group was then further subdivided into a group that breathed unimpeded (control) and a second group that breathed through an inspiratory resistor until the animals were unable to sustain 70% of their maximum airway pressure. Diaphragm samples were obtained for analysis of thiobarbituric acid-reactive substances, glutathione (GSH) concentrations, and glutathione disulfide (GSSG) concentrations. In vitro isometric contractile studies were also performed and included twitch (Pt) and maximum tetanic (Po) tensions, force-frequency curves, fatigue index, and recovery index. Pt was significantly reduced in the E-suf RB group as well as both of the E-def groups. Po was also significantly reduced in both E-def groups. The E-def rats subjected to RB showed a significant decrease in tension at both high and low frequencies compared with the E-suf rats. Concentrations of diaphragm thiobarbituric acid-reactive substances were significantly increased in both E-def groups. RB in both E-suf and E-def rats resulted in increases in diaphragm concentrations of GSSG and decreases in the GSH/GSSG ratios. We conclude that reduction of contractile function, lipid peroxidation, and activation of the GSH redox cycle occur with RB and that these effects are significantly increased in the presence of vitamin E deficiency.

Diaphragmatic function after resistive breathing in vitamin E-deficient rats

The effects of vitamin E deficiency on diaphragm function were studied at rest and after resistive breathing (RB) in Sprague-Dawley rats (wt 300-400 g). The animals were pair fed a vitamin E-deficient diet (E-def) or a matched vitamin E-sufficient diet (E-suf). Each diet group was then further subdivided into a group that breathed unimpeded (control) and a second group that breathed through an inspiratory resistor until the animals were unable to sustain 70% of their maximum airway pressure. Diaphragm samples were obtained for analysis of thiobarbituric acid-reactive substances, glutathione (GSH) concentrations, and glutathione disulfide (GSSG) concentrations. In vitro isometric contractile studies were also performed and included twitch (Pt) and maximum tetanic (Po) tensions, force-frequency curves, fatigue index, and recovery index. Pt was significantly reduced in the E-suf RB group as well as both of the E-def groups. Po was also significantly reduced in both E-def groups. The E-def rats subjected to RB showed a significant decrease in tension at both high and low frequencies compared with the E-suf rats. Concentrations of diaphragm thiobarbituric acid-reactive substances were significantly increased in both E-def groups. RB in both E-suf and E-def rats resulted in increases in diaphragm concentrations of GSSG and decreases in the GSH/GSSG ratios. We conclude that reduction of contractile function, lipid peroxidation, and activation of the GSH redox cycle occur with RB and that these effects are significantly increased in the presence of vitamin E deficiency.