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The contributions of anti-Topoisomerase 1 (Top1) autoantibodies to the pathophysiology of diffuse cutaneous systemic sclerosis (dcSSc), the most aggressive scleroderma subtype, are unknown. Top1 catalyzes DNA relaxation and unwinding in cell nuclei, a site previously considered inaccessible to antibodies. The discovery of autoantibodies in systemic lupus erythematosus that penetrate nuclei and inhibit DNA repair raised the possibility that nuclear-penetrating autoantibodies contribute to mechanisms of autoimmunity. Here we show that an anti-Top1 autoantibody produced by a single B cell clone from a patient with dcSSc penetrates live cells and localizes into nuclei. Functionally, the autoantibody inhibits formation of the Top1 cleavage complex necessary for DNA nicking, which distinguishes it from cytotoxic camptothecin Top1 inhibitors used in cancer therapy that trap the cleavage complex rather than preventing its formation. Discovery of a patient-derived cell-penetrating scleroderma anti-Top1 autoantibody that inhibits Top1 cleavage complex formation supports the hypothesis that anti-Top1 autoantibodies contribute to cellular dysfunction in dcSSc and offers a valuable antibody reagent resource for future studies on anti-Top1 autoantibody contributions to scleroderma pathophysiology., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: James E. Hansen, MD reports financial support was provided by Patrys Ltd. James E. Hansen, MD reports a relationship with Patrys Ltd that includes: consulting or advisory, equity or stocks, funding grants, and non-financial support. James E. Hansen, MD has patents licensed to Patrys Ltd. James E. Hansen, MD has patent pending to unlicensed. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely distributed in the pig population in many countries, where its presence is undesirable, because as an opportunistic human pathogen, it poses a threat to human health. At present, there is a lack of knowledge regarding successful methods for eradication of LA-MRSA on a pig farm, which does not involve emptying the farm and culling all pigs. Some studies have reported an association between levels of LA-MRSA in the barn air and LA-MRSA carriage among humans entering or working in the pig barns. Therefore, interventions that are able to reduce the amount of LA-MRSA carried by the pigs and/or the concentration of LA-MRSA in the barn air, might be highly relevant if aiming for reducing the spread of LA-MRSA into the general human population. In the present study, an existing agent-based simulation model for spread of LA-MRSA within a pig herd was extended to also include LA-MRSA load and spread through air. This makes it possible to use the model for studying the air exposure to LA-MRSA for humans entering the pig barns. The model was used for simulating various types of interventions in contaminated herds. At present quantitative data for nasal carriage of LA-MRSA in pigs are sparse, and many knowledge gaps regarding spread of LA-MRSA remain. Thus, our goal of building this model was not to provide exact values for risk reduction, but to avail a model that can be used for studying the effect of various types of interventions mechanistically, once more relevant data become available. Collection of more data on the influence of load is crucial for getting a better understanding of which possible interventions strategies, that might still have some potential in countries, where LA-MRSA has already spread to the majority of the pig population., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Systemic lupus erythematosus is associated with a small overall increased cancer risk compared with the general population. This risk includes a 4-fold increased risk of non-Hodgkin lymphoma, but a decreased risk of other cancers (such as breast cancer). The pathophysiology underlying the increased risk of hematologic cancer is not fully understood, but many potential mechanisms have been proposed, including dysfunction of the tumor necrosis factor and other pathways. A decreased risk of breast, ovarian, and endometrial cancer might be driven by hormonal factors or lupus-related antibodies, but these links have not been proved., Competing Interests: Disclosure None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: Initial deescalation studies for human papilloma virus (HPV)-positive driven oropharyngeal squamous cell carcinomas (HPV+ OPSCC) altered radiation therapy dose or the systemic agent used. Newer trials examine the disease control achieved with a reduced elective nodal field. We examined patterns of nodal involvement in patients with HPV+ OPSCC with a focus on implications for radiation field design for treatment deescalation., Methods and Materials: Records of patients with HPV+ OPSCC with preoperative imaging (computed tomography or fludeoxyglucose positron emission tomography/computed tomography) who underwent neck dissection without neoadjuvant therapy from 2010 to 2017 were retrospectively reviewed. The number and location of clinically positive lymph nodes on preoperative imaging were compared with those documented on pathology. These data were then used to establish the probability of missing nodal disease in 3 modified radiation field designs., Results: One hundred patients were included. The median time between imaging and surgery was 22 days. The most common clinical N stage was cN2a (35%), whereas the most common pathologic N stage was pN2b (45%). The median number of radiographically and pathologically involved nodes was 1 (range, 0-6) and 2 (range, 0-11), respectively. Forty-three percent of patients had more pathologically involved nodes than predicted on imaging, whereas 21% had pathologic involvement at an additional nodal level not predicted on imaging. Of the 21 patients with additional pathologically involved nodal levels, 14 had involvement of a directly adjacent station, 4 were patients with a cN0 hemineck with pathologically positive level II disease, and 3 had pathologic involvement of level 2 echelons removed from that predicted on imaging., Conclusion: Our study suggests that radiation fields encompassing only clinically involved nodes or levels has an unacceptably high likelihood of missing subclinical disease. Alternatively, treating the first uninvolved echelon nodes in addition would cover pathologic sites of disease in 97% of patients. This approach merits further study in prospective trials., (Copyright © 2018. Published by Elsevier Inc.)

A key challenge in the development of novel chemotherapeutics is the design of molecules capable of selective toxicity to cancer cells. Antibodies have greater target specificity compared to small molecule drugs, but most are unable to penetrate cells, and predominantly target extracellular antigens. A nuclear-penetrating anti-DNA autoantibody isolated from the MRL/lpr lupus mouse model, 3E10, preferentially localizes to tumors, inhibits DNA repair, and selectively kills cancer cells with defects in DNA repair. A murine divalent single chain variable fragment of 3E10 with mutations for improved DNA binding affinity, 3E10 (D31N) di-scFv, has previously been produced in P. pastoris and yielded promising pre-clinical findings, but is unsuitable for clinical testing. The present study reports the design, expression and testing of a panel of humanized 3E10 (D31N) di-scFvs, some of which contain CDR substitution. These variants were expressed in a modified CHO system and evaluated for their physicochemical attributes and ability to penetrate nuclei to selectively cause DNA damage accumulation in and kill cancer cells with DNA repair defects. Secondary structure was conserved and most variants retained the key characteristics of the murine 3E10 (D31N) di-scFv produced in P. pastoris. Moreover, several variants with CDR substitutions outperformed the murine prototype. In conclusion, we have designed several humanized variants of 3E10 (D31N) di-scFv that have potential for application as monotherapy or conjugates for targeted nuclear drug delivery., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: In chronic obstructive pulmonary disease, both smaller and larger airways are affected. FEV 1 mainly reflects large airways obstruction, while the later fraction of forced exhalation reflects reduction in terminal expiratory flow. In this study, the objective was to evaluate the relationship between spirometric ratios, including the ratio of forced expiratory volume in 3 and 6 seconds (FEV 3 /FEV 6 ), and small airways measures and gas trapping at quantitative chest CT scanning, and clinical outcomes in the Genetic Epidemiology of COPD (COPDGene) cohort., Methods: Seven thousand eight hundred fifty-three current and ex-smokers were evaluated for airflow obstruction by using recently defined linear iteratively derived equations of Hansen et al to determine lower limit of normal (LLN) equations for prebronchodilator FEV 1 /FVC, FEV 1 /FEV 6 , FEV 3 /FEV 6 , and FEV 3 /FVC. General linear and ordinal regression models were applied to the relationship between prebronchodilator spirometric and radiologic and clinical data., Results: Of the 10,311 participants included in the COPDGene phase I study, participants with incomplete quantitative CT scanning or relevant spirometric data were excluded, resulting in 7,853 participants in the present study. Of 4,386 participants with FEV 1 /FVC greater than or equal to the LLN, 15.4% had abnormal FEV 3 /FEV 6 . Compared with normal FEV 3 /FEV 6 and FEV 1 /FVC, abnormal FEV 3 /FEV 6 was associated with significantly greater gas trapping; St. George's Respiratory Questionnaire score; modified Medical Research Council dyspnea score; and BMI, airflow obstruction, dyspnea, and exercise index and with shorter 6-min walking distance (all P < .0001) but not with CT scanning evidence of emphysema., Conclusions: Current and ex-smokers with prebronchodilator FEV 3 /FEV 6 less than the LLN as the sole abnormality identifies a distinct population with evidence of small airways disease in quantitative CT scanning, impaired indexes of physical function and quality of life otherwise deemed normal by using the current spirometric definition., (Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Aquaporin 0 (AQP0) is an integral membrane protein that facilitates water transport and cellular adhesion in the lens. Its dysfunction has been associated with cataractogenesis. Our earlier studies showed AQP0 undergoes aggregation when subjected to thermal stress and this aggregation seems to have been facilitated by mechanical agitation brought about by gentle stirring. The purpose of this study is to determine the secondary structural changes that precede aggregation and the role that α-crystallin plays in inhibiting those structural changes. Detergent solubilized calf lens AQP0 was subjected to thermal stress at 50°C for varying times. Secondary structural changes were measured by Circular Dichroism (CD) spectropolarimetry. Convex constraint analysis was used to deconvolute the CD spectra into pure component curves representing the secondary structural elements. Our results showed that under thermal stress, the α-helix content of AQP0 decreased from 50% to 7% with a concomitant increase from 0% to 52% in β-sheet content. The time-dependent loss of α-helical structure and gain of β-sheet structure appear to follow first-order kinetics with very similar values (∼30min) suggesting a single transition. In the presence of α-crystallin, this conversion to β-sheet is minimized, suggesting that the protein structure that binds to the molecular chaperone is mostly the α-helical structure of AQP0., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The systemic lupus erythematosus (SLE) population has a unique cancer risk profile. This article presents the most recent data on risk of cancer in lupus and discusses possible contributing factors. The risk of lymphoma is particularly increased in SLE and may be mediated by immunosuppressive medication. Lung cancer risk is also increased in SLE. There is a high rate of cervical dysplasia in women with SLE. A similar pathophysiology could be responsible for the trend seen in vulvovaginal and hepatic carcinomas. There is a decreased risk in SLE for some hormone-sensitive cancers, but the cause of this remains unclear., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background and Aims: Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations., Methods and Results: Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given., Conclusion: Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: The responses of oxygen uptake efficiency (ie, oxygen uptake/ventilation = VO(2)/VE) and its highest plateau (OUEP) during incremental cardiopulmonary exercise testing (CPET) in patients with chronic left heart failure (HF) have not been previously reported. We planned to test the hypothesis that OUEP during CPET is the best single predictor of early death in HF., Methods: We evaluated OUEP, slope of VO(2) to log(VE) (oxygen uptake efficiency slope), oscillatory breathing, and all usual resting and CPET measurements in 508 patients with low-ejection-fraction (< 35%) HF. Each had further evaluations at other sites, including cardiac catheterization. Outcomes were 6-month all-reason mortality and morbidity (death or > 24 h cardiac hospitalization). Statistical analyses included area under curve of receiver operating characteristics, ORs, univariate and multivariate Cox regression, and Kaplan-Meier plots., Results: OUEP, which requires only moderate exercise, was often reduced in patients with HF. A low % predicted OUEP was the single best predictor of mortality (P < .0001), with an OR of 13.0 (P < .001). When combined with oscillatory breathing, the OR increased to 56.3, superior to all other resting or exercise parameters or combinations of parameters. Other statistical analyses and morbidity analysis confirmed those findings., Conclusions: OUEP is often reduced in patients with HF. Low % predicted OUEP (< 65% predicted) is the single best predictor of early death, better than any other CPET or other cardiovascular measurement. Paired with oscillatory breathing, it is even more powerful.

Background: Extensively used current guidelines of the American Thoracic Society/European Respiratory Society (ATS/ERS) define a positive aerosolized bronchodilator (BD) response as: "...an increase in FEV(1) and/or FVC > or = 12% of control and > or = 200 mL." We hypothesized that BD responsiveness was better assessed using a statistical approach, linked to each individual's spirometric measurements, rather than the variability of others., Design: We retrospectively analyzed 1-year's pre- and post-BD spirometric tests from our hospital's clinical laboratory. Using measurements of forced expiratory volume in 1-s (FEV(1)), forced expiratory volume in 3-s (FEV(3)), and forced vital capacity (FVC) from each of three satisfactory forced pre-BD and three satisfactory forced post-BD spirometric maneuvers, we classified each of 313 consecutive patient studies as responders or non-responders in two ways. First, we used ATS/ERS guideline criteria based on population variability. Second, we used unpaired, single-tailed t-tests at P<0.05 for FEV(1), FEV(3), and FVC, considering the variability of and difference between each individual's pre- and post-BD maneuvers., Results: 135 studies were both ATS/ERS and t-test non-responders, three were ATS/ERS responders and t-test non-responders, 86 were ATS/ERS and t-test responders, and 89 were ATS/ERS non-responders and t-test responders. The latter 89 included many patients with either low baseline FEV(1) (< 1.50 L) who could not reach the 200 mL increase criterion or high baseline FEV(1) (> 3.00 L) who could not reach the 12% increase criterion., Conclusions: We believe individual t-tests may categorize patient's BD responsiveness better than ATS/ERS guideline criteria which are based on population responses and require both fixed volume and percentage changes. Its usefulness by others remains to be shown.

Background: Mismatching of ventilation to perfusion is found in patients with COPD, left ventricular failure (LVF), and pulmonary vascular diseases. Such mismatching may be due to ventilation or perfusion defects or both. Our primary hypothesis was that pressures of mixed-expired CO2 pressure (Peco(2)), end-tidal Pco(2) pressure (Petco(2)), and their ratios would differ between groups during exercise testing, depending on whether the ventilation/perfusion (V/Q) abnormality was dominantly caused by airways or perfusion defects., Methods: We administered incremental cycle ergometry tests to 25 normal subjects and three groups of 25 patients, each group with uncomplicated COPD, LVF, or primary pulmonary arterial hypertension (PAH). We compared Peco(2), Petco(2), and their ratios at rest, unloaded pedaling, anaerobic threshold, and peak exercise., Results: Although each patient group had mean peak O(2) uptake of approximately 50% of predicted normal, the levels and patterns of change for each group for Peco(2), Petco(2), and their ratios were surprisingly distinctive. As hypothesized, the COPD group always had markedly lower Peco(2)/Petco(2) ratios than all other groups (p < 0.001). In addition, patients with LVF had slightly lower Peco(2)/Petco(2) ratios at heavy exercise than normal subjects (p < 0.05). At all times, except for COPD group Petco(2) at peak exercise, each group had significantly lower Petco(2) and Peco(2) than normal subjects (p < 0.001). In patients with PAH, the Petco(2) decline with exercise was distinctive., Conclusions: The levels and changes in Peco(2), Petco(2), and their ratios during cardiopulmonary exercise testing are distinctive and explained by the differing pathophysiologies of V/Q mismatching in these disorders.

Background: Biventricular pacing (BVP) is used for cardiac resynchronization therapy in wide-QRS-complex heart failure. We sought to quantify the effect of BVP on the exercise pathophysiology of heart failure patients., Methods: Using cardiopulmonary exercise testing, we analyzed exercise data for a multicenter study sponsored by St. Jude Medical. Patients had pacemaker electrodes implanted in both ventricles in the standard manner and were randomized by St. Jude before exercise testing. Exercise measurements included peak oxygen uptake (Vo(2)), peak O(2) pulse, anaerobic threshold (AT), and ventilatory equivalent for CO(2) (reflecting change in peak exercise cardiac output, stroke volume, maximal sustainable exercise capacity, and ventilation-perfusion mismatching, respectively) at baseline and at a 6-month follow-up. The studies included progressively and uniformly increasing work rate to maximum tolerance. The investigators were blinded both to sponsor-controlled randomization and pacemaker status. There were 239 paired 6-month studies, as follows: 47 studies served as the control with the pacemaker off (ie, the BVP-OFF group); and 192 patients received pacing (ie, the BVP-ON group)., Results: The BVP-ON group significantly improved in all exercise parameters in contrast to the control group (p < 0.0001). When baseline measurements for the BVP-ON group were ranked in quintiles, only patients in the three functionally worst quintiles improved significantly at 6 months (peak Vo(2) < 11.6 mL/min/kg, AT < 7.6 mL/min/kg, peak O(2) pulse < 12.0 mL/beat, and minute ventilation/Vco(2) ratio at AT > 38.1) [p < 0.01 to < 0.0001]., Conclusion: BVP benefited aerobic function and ventilation-perfusion mismatching most in those patients with the greatest physiologic impairment.

Background: Current authoritative spirometry guidelines use conflicting percentage of FEV1/FVC ratios (FEV1/FVC%) to define airway obstruction. The American Thoracic Society/European Respiratory Society Task Force characterizes obstruction as a FEV1/FVC% below the statistically defined fifth percentile of normal. However, many recent publications continue to use the Global Initiative for Chronic Obstructive Lung Disease (GOLD) primary criterion that defines obstruction as a FEV1/FVC% < 70%. Data from the Third National Health and Nutrition Examination Survey (NHANES-III) should identify and quantify differences, help resolve this conflict, and reduce inappropriate medical and public health decisions resulting from misidentification., Methods: Using these two guidelines, individual values of FEV1/FVC% were compared by decades in 5,906 healthy never-smoking adults and 3,497 current-smokers of black (African American), Hispanic (Latin), or white ethnicities aged 20.0 to 79.9 years., Results: In the never-smoking population, the lower limits of normal used in other reference equations fit reasonably well the NHANES-III statistically defined fifth percentile guidelines. But nearly one half of young adults with FEV1/FVC% below the NHANES-III fifth percentile of normal were misidentified as normal because their FEV1/FVC% was > 70% (abnormals misidentified as normal). Approximately one fifth of older adults with observed FEV1/FVC% above the NHANES-III fifth percentile had FEV1/FVC% ratios < 70% (normals misidentified as abnormal)., Conclusions: The GOLD guidelines misidentify nearly one half of abnormal younger adults as normal and misidentify approximately one fifth of normal older adults as abnormal.

Objectives: To develop mean and 95% confidence limits for the lower limit of normal (LLN) values for forced expiratory volume in 3 s (FEV3)/FVC ratio for Latin, black, and white adults; to ascertain comparative variability of the FEV1/FVC ratio, the FEV3/FVC ratio, and forced expiratory flow, midexpiratory phase (FEF(25-75)) in never-smoking adults; to evaluate their utility in measuring the effect of smoking on airflow limitation; and to develop and use the fraction of the FVC that had not been expired during the first 3 s of the FVC (1 - FEV3/FVC) to identify the growing fraction of long-time-constant lung units., Design: Analysis of the Third National Health and Nutrition Examination Survey (NHANES III) database of never-smokers and current smokers., Participants: A total of 5,938 adult never-smokers and 3,570 current smokers from NHANES III with spirometric data meeting American Thoracic Society standards., Measurements and Results: After establishing new databases for never-smokers and current smokers, we quantified the mean and LLN values of FEV3/FVC in never-smokers, and identified spirometric abnormalities in current smokers. When associated with older age, FEV3/FVC decreases and 1 - FEV3/FVC increases as FEV1/FVC decreases. On average, using these measurements, the condition of current smokers worsened about 20 years faster than that of never-smokers by middle age. If < 80% of the mean predicted FEF(25-75) was used to identify abnormality, over one quarter of all never-smokers would have been falsely identified as being abnormal. Using 95% confidence limits, 42% of 683 smokers with reduced FEV1/FVC and/or FEV3/FVC would have been judged as normal by FEF(25-75)., Conclusions: FEV1/FVC, FEV3/FVC, and 1 - FEV3/FVC characterize expiratory obstruction well. In contrast, FEF(25-75) measurements can be misleading and can cause an unacceptably large number of probable false-negative results and probable false-positive results.

Objectives: Primary pulmonary hypertension (PPH) is a pulmonary vasculopathy resulting in exercise intolerance, usually due to dyspnea. We hypothesized that ventilation is increased during exercise in PPH relative to normal because the ventilated lung is underperfused, cardiac output increase is restricted, and arterial hypoxemia may develop. Our aim was to determine the size of the reduction in end-tidal Pco(2) (Petco(2)) as a reflection of the abnormality in ventilatory efficiency and ventilatory drive in PPH patients., Methods: We performed cardiopulmonary exercise testing (CPET) in 52 PPH patients. All had hemodynamic measurements to confirm the diagnosis of PPH. A subgroup of 29 patients who underwent right-heart catheterization within 50 days of CPET were studied to compare their CPET responses to resting hemodynamics. Nine healthy volunteers matched for age and gender served as CPET control subjects., Results: In PPH patients, the percentage of predicted peak oxygen uptake (Vo(2)) correlated significantly with mean pulmonary artery pressure (mPAP) [r = - 0.59, p = 0.0007, n = 29]. Petco(2) values at rest, anaerobic threshold (AT), and peak Vo(2) were proportionately reduced as percentage of predicted peak Vo(2) decreased (r = 0.66 to 0.72, p < 0.0001, n = 52). Petco(2) values at rest, AT, and peak Vo(2) were also reduced as mPAP increased (r = - 0.51 to - 0.53, p < 0.005, n = 29). In contrast to normal subjects in whom Petco(2) increased from rest to AT, Petco(2) decreased in PPH patients, except for two patients with mild PPH in whom there was no change. Also, Petco(2) increased rather than decreased further at the start of recovery, in contrast to normal. Although usually normal at rest, oxyhemoglobin saturation decreased during exercise in most PPH patients., Conclusions: In patients with PPH, Petco(2) at rest and exercise is significantly reduced in proportion to physiologic disease severity. The range of values is unusually low. Furthermore, the directional changes of Petco(2) during exercise and early recovery are in the opposite direction of normal.

Background and Objectives: As part of a recent study, cardiopulmonary exercise tests (CPETs) were used to evaluate and follow up patients with pulmonary arterial hypertension (PAH). These patients were more impaired than those in other published series evaluating CPET reproducibility. We used these patient tests to assess patient performance variability and evaluate reading variability. To achieve this end, six independent evaluators graded key CPET measurements in patients with PAH who underwent duplicate CPETs within 3 days of each other., Setting and Patients: Over a 15-month period at two tertiary-care teaching hospitals, 42 patients with PAH underwent repeated, paired CPETs using cycle ergometry., Interventions and Measurements: Each patient underwent one to six pairs of cycle ergometry tests to maximal tolerance. Each pair of tests was separated by 3 months, with each test in the pair separated by 1 to 3 days. Specific guidelines were given to the independent evaluators for the key measurements assessed from each CPET study: peak O(2) uptake (Vo(2)), peak heart rate, peak O(2) pulse, anaerobic threshold (AT), and end-tidal Po(2), end-tidal Pco(2), and the ventilatory equivalent for CO(2) at the AT (Ve/Vco(2)@AT)., Results: There were no fatalities or complications occurring among the 242 tests performed on 42 patients. The mean peak Vo(2) was 722 mL/min or 41% of predicted; 34 patients were Weber class C or D. Using the specific guidelines to measure the variability of measurements made by the six independent evaluators, the coefficients of variation were < 2.2% for peak Vo(2), peak heart rate, peak O(2) pulse, end-tidal values at the AT, and Ve/Vco(2)@AT, while for the AT, it was 8.5%. There were no significant differences in these measurements between the first and second tests of any pair or between the earlier and later sets of pairs., Conclusions: Using specific guidelines, key CPET measurements can be safely, reliably, and reproducibly assessed even in patients with severe exercise intolerance.

Study Objectives: The ventilatory equivalent for CO(2) (ie, the ratio of minute ventilation [VE] to carbon dioxide output [VCO(2)]) is increased in patients with primary pulmonary hypertension (PPH) consequent to an increase in physiologic dead space and alveolar ventilation. We wished to see whether the VE/V(2) ratio correlated with the abnormality in pulmonary hemodynamics in PPH patients and whether it changed in response to prostacyclin infusion., Methods: Following right-sided heart catheterization, 10 patients with severe PPH were studied in the coronary-care unit while hemodynamic and gas exchange measurements were measured simultaneously before and after infusion with epoprostenol (Epo), a prostacyclin analog. Studies were performed at baseline and during IV infusion of two to three increasing dosages of Epo in 10 PPH patients (NYHA class III-IV). Four patients had radial artery catheters for simultaneous blood gas measurements. Nine healthy subjects who were matched by sex, height, and weight underwent gas exchange analyses only., Results: The mean (+/- SD) VE/VCO(2) ratio was higher in PPH patients than in control subjects (50.7 +/- 9.7 vs 30.6 +/- 3.8; p < 0.001). Thirteen measurements made in four patients showed that the VE/VCO(2) ratio correlated with the physiologic dead space/tidal volume ratio (r = 0.78; p = 0.002). The VE/VCO(2) ratio measurement at baseline correlated significantly with total pulmonary vascular resistance (TPVR) (r = 0.70; p = 0.02) but not with mean pulmonary artery pressure (mPAP) or cardiac index. During Epo infusion, the VE/VCO(2) ratio decreased with increasing dosage in 6 of 10 patients, with no change or slight increases in the 4 remaining patients. Considering all doses, the VE/VCO(2) ratio decreased significantly in response to the short-term administration of Epo. The decrease tended to parallel the pattern of decrease in TPVR, but the changes in both variables were too small to provide a statistically significant correlation. The mPAP did not change significantly in response to Epo infusion, although TPVR did change at the highest dosage., Conclusions: In patients with severe PPH, the VE/VCO(2) ratio correlated significantly with TPVR but not with mPAP or cardiac index. The VE/VCO(2) ratio decreased systematically from baseline with the dose of Epo in some but not all patients. The VE/VCO(2) ratio and TPVR decreased significantly in response to Epo when all doses were considered. Further studies are needed to elucidate whether noninvasive gas exchange measurements may be clinically useful in the evaluation of the severity of pulmonary vascular disease and the effectiveness of pulmonary vasodilator therapy.

Background and Study Objective: Theoretically, cardiac output (CO) calculated by the Fick principle should be the same using O(2) (CO[O2]) or CO2 (CO[CO2]) as the test gas. However, agreement depends on the accuracy of gas exchange and blood gas measurements and the validity of the equations to convert measured variables into blood gas contents. Considering the widespread use of indirect estimates of pulmonary artery blood PCO2 and CO2 content to measure Fick principle CO during exercise, we wished to determine whether CO[O2] and CO[CO2] were equal during exercise and whether CO[CO2] could be accurately and precisely determined using direct measures of pulmonary artery blood. PREPARATION AND METHODS: Five healthy young nonsmoking volunteer men performed incremental exercise from rest to peak exercise on two separate occasions with intervening rest. Catheters were placed in brachial and pulmonary arteries to allow repeated blood sampling every minute during concurrent breath-by-breath gas exchange measurements from rest to peak exercise. CO[O2] was compared with CO[CO2] at multiple levels of exercise. Using standard equations, arterial and mixed venous O2 contents were calculated from hemoglobin concentration (Hb), oxyhemoglobin saturation (SO2), and PO2, whereas CO2 contents were calculated from PCO2, pH, Hb, and SO2. Blood gas analyzers were used for measurement of pH, PCO2, and PO2, and a co-oximeter was used for measurement of Hb and SO2. Initial calculations suggested that exercise CO[CO2] was 14% higher than CO[O2] and helped disclose small systematic measurement errors in PCO(2) for values > 45 mm Hg detected by proficiency testing surveys and documented with blood tonometry in the blood gas analyzer., Results: After correcting PCO2 for the small systematic measurement error found, the measures and equations used to calculate arterial and mixed venous O2 and CO2 contents were adequate to provide mean CO values that are reasonably similar. However CO[CO2] values were more than twice as variable as CO[O2]., Conclusions: The increased variability of Fick principle CO[CO2] compared with CO[O2] is attributable to the much lower extraction ratio for CO2 and the greater complexity in calculation of blood CO2 than O2 contents. These results raise concerns about the accuracy and precision of estimating CO and stroke volume using CO2 as a test gas, even with direct measurement of blood CO2 contents in normal subjects.

Study Objectives: To ascertain the degree of dissimilarities among blood gas and pH analyzer models of the same and different manufacturers in measurement of PO2, PCO2, and pH using fluorocarbon containing emulsion (FCE) proficiency testing material., Design: Statistically and graphically analyze data from six recent proficiency testing surveys for the 20 more frequently used models of analyzers., Setting and Participants: Over a 2-year period, approximately 900 participants from blood gas laboratories in the United States analyzed similar ampules from each of 30 lots., Measurements and Results: Both graphic and statistical comparisons were used to demonstrate differences between manufacturers. For each of the four major manufacturers, comparisons revealed statistically significant differences not only for PO2, but also for PCO2 and pH. Additionally, comparison models within each of the three manufacturers (those with multiple models and > 15 instruments per model represented) disclosed statistically significant dissimilarities among models for each analyte in 115 of 153 model pairings. Previously reported tonometered blood differences among analyzer models for PO2 are qualitatively similar to the differences found in these same models in this FCE study. Model differences are important in research studies and may be clinically important in deciding abnormality, selecting oxygen therapy, or the treatment of patients with respiratory failure or severe respiratory alkalosis., Conclusions: To minimize the likelihood of misleading clinicians, laboratory directors should consider the degree of dissimilarity among blood gas analyzer models in current use and when changing instrumentation.

In order to offer a gene therapy-based treatment against AIDS, it is likely to be necessary to harvest and culture CD4 cells from HIV-positive patients without activating the HIV infection. We have used a magnetic cell sorting (MACS) system to enrich CD4 cells. Using positive selection, CD4 cells from a total of 14 patients were enriched from a mean percentage of CD4 cells in PBMC of 18% to 91% CD4 cells in the enriched cell fraction. Furthermore, we found that this separation did not lead to an increase in viral load. The MACS performed equally well on cells from HIV-positive patients and HIV-negative donors. CD4 cells from HIV-positive patients were readily expanded with PHA; 19-fold by day 10, 50-fold by day 20, and 156-fold by day 25. However, CD4 cells from HIV-positive patients grew at a slower rate than CD4 cells from HIV-negative donors. The expanded CD4 cells showed a high degree of CD4 expression and no loss of polyclonality. Only in two of six cultures were we able to detect HIV-antigen production, and using an LTR-PCR and an RT assay, we did not find activation of the HIV infection during the culture period. Thus, the method described separates and expands CD4 cells from HIV-positive patients without activation of the HIV infection.

Objective: To analyze the relative importance of gas exchange, ventilatory, and circulatory abnormalities in limiting exercise in patients with interstitial lung disease., Design and Setting: Retrospective study at a referral cardiopulmonary exercise laboratory in a university/county medical center., Patients and Methods: A database with more than 1,300 patients with incremental cycle exercise studies was screened to find 42 patients with interstitial lung disease, but without accompanying airflow limitation, chest wall, primary heart, or systemic vascular disease, or poor motivation. All had spirometry, lung volume, and gas transfer index measures at rest and repeated gas exchange, ventilatory, and circulatory measures during exercise; 37 of the 42 patients had multiple blood gas measures during exercise. We graded the gas exchange, ventilatory and circulatory dysfunction during maximally tolerated cycle ergometry and correlated the grades of dysfunction of these three components of respiration with percent predicted peak O2 uptake (peak Vo2)., Results: Peak Vo2 values were not well correlated with the grades of ventilatory impairment but were well correlated with the grades of gas exchange and circulatory dysfunction. Patients who had reduced peak Vo2 values often had a normal breathing reserve with physiologic evidence of pulmonary vascular disease., Conclusions: The pathophysiology of the pulmonary circulation is usually more important than ventilatory mechanics in limiting exercise in patients with interstitial lung disease.

A 15-mer C-5 propyne modified phosphorothioate oligodeoxynucleotide antisense to rev was approximately 5-fold more effective in providing viral inhibition compared to a 28-mer unmodified phosphorothioate oligodeoxynucleotide targeted to the same sequence and previously shown to inhibit HIV-1 in a sequence-dependent manner. The antiviral effect was obtained by lipofection or simple addition of 0.2-1 microM modified oligodeoxynucleotide to the culture medium of H9 cells chronically infected with the HIV-1LAI isolate of human immunodeficiency virus type 1. We conclude that C-5 propyne oligodeoxynucleotides in accordance with previous findings by others are superior to unmodified phosphorothioates in providing inhibition of HIV-1 in a sequence-dependent manner and that this inhibition can be conferred by oligodeoxynucleotides in free solution.

Objective: Because published criteria for bronchodilator responsiveness are based on population variability and compare only the single best measures before and after intervention, we hypothesized that the variability of the FEV1 and FEV3 of each patient would better determine that patient's responsiveness., Design and Interventions: Five 3-s forced expiratory maneuvers were used for each of 3 sequential portions of the study: baseline, after nebulized saline solution, and after nebulized albuterol., Setting: Clinical pulmonary function laboratory in a county/university teaching hospital., Patients: Fifty consecutive adult patients with obstruction referred for routine testing and thought to be able to complete the study. (The primary diagnoses were found to be equally divided between asthma, bronchitis, and emphysema; equal numbers had very severe, severe, moderate, mild, or minimal obstruction.), Measurements and Results: The primary finding was that 36 patients were found to be responders (consistent and statistically significant FEV1 and FEV3 improvement after albuterol). The 14 identified as nonresponders would have been so categorized by all other published criteria. For assessing responsiveness, we found FEV3 measures preferable to vital capacity measures, because the latter depends on the duration of the maneuver., Conclusions: The percentage of responders identified is higher than recognized by any other published criteria. Most criteria would not have identified the responders with very severe or minimal airways obstruction.

There is scant objective information regarding the effect of proficiency testing for blood gases or other analytes on characterizing poor or good performers or changing laboratory behavior. Following the institution of a percentile ranking system for participants in the American Thoracic Society--California Thoracic Society Blood Gas Proficiency Testing Programs, a telephone survey disclosed characteristics of three equally sized groups of participants as follows: (1) FAIL (failed rating); (2) LOW (lowest percentile rankings without a failed rating); and HIGH (highest percentile rankings). The FAIL and LOW groups often had isolated instruments, instruments which were infrequently operated, and/or instruments operated by nontechnicians, whereas these characteristics were not found in the HIGH group. Those in the LOW group who understood their ranking and those in the FAIL group always found defects or errors and took some corrective action. This study appears to show that it is harder to maintain good performance with isolated, underutilized, or nontechnician-operated blood gas instruments, and blood gas proficiency testing is economical and valuable in assessing performance and changing behavior.

Monoclonal antibodies (mAbs) against carbohydrate epitopes of gp120 have recently been found to inhibit HIV infection of lymphocytes in vitro thereby opening new possibilities for vaccine considerations. Antibody-dependent enhancement of infection has however come increasingly into focus. This study therefore investigated the neutralization of HIV in a monocytic cell line (U937) using mAbs against these carbohydrate gp120-epitopes. While antibodies against one of the epitopes (AI) neutralized infection of U937 cells despite binding to the Fc-receptor, one mAb against the sialosyl-Tn epitope enhanced infection. This enhancement was independent of complement and could be blocked by mAb Leu3a against the CD4-receptor. The study indicated that enhancement of infection in monocytic cells can occur by the same anti-carbohydrate antibodies that neutralize infection in lymphocytes, and that antibody mediated enhancement may depend on location of the epitope on gp120 rather than whether the antibody binds Fc-receptors.

Three water-soluble derivatives of amphotericin B were tested for inhibition of HIV infection in vitro. The compounds amphotericin B methyl ester (AME) and N-(N'-(2-(4'-methylmorpholinio)ethyl)N"-cyclohexyl guanyl) amphotericin B methyl ester (MCG) inhibited HIV infection by 50% at 1 microgram/ml; N-(N'-(3-dimethylaminopropyl)N"-ethyl guanyl) amphotericin B (DAPEG) did so at 5-11 micrograms/ml. While the virus-inhibitory effect of AME was due to an interaction with target lymphocytes, the effect of MCG was due to a direct anti-viral action. AME increased the potential of infected cells to fuse with uninfected cells, but MCG had no significant effect on cell fusion. All compounds had a lower cellular toxicity than amphotericin B and were not toxic at concentrations below 20 micrograms/ml.

The California Thoracic Society Blood Gas Proficiency Testing Program distributed ampules from three separate lots of quality control products every three months as unknowns to participating clinical (survey) laboratories and ten selected reference laboratories. For eight quarters, aqueous buffers were distributed. For each lot, PCO2 and pH measurements varied within narrow ranges between laboratories. Concurrently, the PO2 measurements varied widely between reference laboratories as well as survey laboratories, but varied minimally when repeatedly assessed on each reference laboratory machine. Change to a fluorocarbon-containing emulsion as a testing medium resulted in a significant reduction in within model and overall variability for PO2. We attribute this reduction in variability to the higher O2 content and decreased temperature sensitivity for PO2 of the fluorocarbon-containing emulsion. Because we have no evidence that the magnitude of the interinstrument differences in PO2 found with these materials would be found with fresh human blood we recommend that regulatory agencies use the results of proficiency testing for PO2 cautiously.

The concentration of alpha 1-acid glycoprotein (AGP, orosomucoid) was measured in sera from 19 patients with primary squamous cell carcinoma of the lung, 16 patients with an inflammatory lung disease and 17 persons with normal health. All sera were further subjected to crossed immuno-affinoelectrophoresis with addition of Con A in the first dimension and sugar in the second dimension. The distribution of AGP into four microheterogeneity forms, which were the result of this analysis, was estimated by measuring the area under the precipitation curve. The microheterogeneity patterns of AGP in the three groups were significantly different from each other (p less than 0.001). The total concentration of AGP in the two groups of patients was significantly different from the concentration in the healthy group (p less than 0.001).

Beta-adrenergic blockade may be hazardous in asthma and chronic obstructive lung disease. The beta-adrenergic antagonist pindolol (LB-46) has been suggested to be more tolerable in such patients. We gave intravenously both 0.4 mg pindolol and placebo to 24 mild to moderate asthmatic subjects in remission. In 23 subjects who completed the study, there was no significant difference in pulmonary function between the pindolol and placebo trials either after drug administration or following exhausting exercise after drug administration, although a trend toward reduced pulmonary function after pindolol was seen. Significant differences (P less than 0.05) were found after inhaled isoproterenol when FEV1 and peak expiratory flow rates were compared. We conclude that in this group of mild to moderate asthmatic subjects, there was no adverse effect from pindolol even during exercise-induced bronchospasm. The response to isoproterenol may have been slightly impaired, but the clinical meaning of this is unclear.

Because of suspicion that the ear oximeter might measure the oxyhemoglobin saturation of arterial blood inaccurately during heavy exercise, we made concurrent ear oximetric and blood measurements on 14 consecutive patients with arterial catheters during clinical exercise tests. After correcting for carboxyhemoglobin, the estimated and measured values for the oxyhemoglobin saturation of the blood agreed well, as did resting ear and blood values; however, during heavy exercise, ear oximetric values were falsely elevated in two patients with interstitial pulmonary disease and were falsely depressed in five patients with cardiovascular limitation to exercise. In another patient, ear oximetric values declined during heavy exercise despite mild hyperoxia, suggesting hypoperfusion of the ear. Considering the clinical and physiologic importance of oxyhemoglobin saturation, ear oximetric values during heavy exercise should be cautiously interpreted.

Although large differences in mean values and standard deviations of PO2 between models of blood gas instruments have been found in proficiency testing surveys employing commercial ampuled material, it is unknown whether or not equivalent differences would be found between instruments if a primary standard (tonometered fresh human blood) were used instead of ampules (secondary control specimens). Therefore, we compared the biases (differences between means) of six models of blood gas instruments using five varieties of ampuled quality control materials and a single source of tonometered fresh human blood at three levels of PO2 (67.5, 91.4, and 143.6 mm Hg). All materials correlated positively with blood, thus demonstrating consistency of machine biases. The coefficients of variation measuring blood and a perfluorocarbon mixture (abc) were not different, but were higher for aqueous and hemoglobin-containing mixtures. On average, at the PO2 levels tested, the differences among instruments were slightly smaller with abc than with blood, but larger with aqueous and hemoglobin-containing materials. Because abc "tracks" tonometered blood reasonably well at the PO2 levels tested, instrument differences in PO2 detected with abc are also likely to be seen with clinical blood samples. The other four quality control materials probably overestimate instrument differences in measuring PO2.

Several calcium antagonists, each with significantly different chemical structures, have demonstrated variable attenuation of exercise-induced asthma. Quantitative comparisons have been hampered by differences in the intensity of challenge and the severity of the underlying disease between groups of patients. In 12 asthmatic adults with relatively severe exercise-induced asthma, we compared the effect of a new calcium antagonist, PY 108-068, in doses of 75 mg and 150 mg with nifedipine (30 mg) and placebo on resting flow rates and flow rates after exercise. Over a three-week period, each patient completed a four-day, randomized, double-blind Latin-square study. After receiving one of four oral drugs, spirometry was repeated every 30 minutes for two hours, followed by a six-minute treadmill exercise test breathing dry air. The exercise tests were well matched for work rate, ventilation, heart rate, and oxygen uptake. Spirometry was then repeated seven times over the next 30 minutes after exercise. Though both 150 mg of PY 108-068 and nifedipine were associated with mild bronchodilation before exercise, only the latter was significant (p less than 0.05). Exercise-induced asthma (expressed as maximal percent fall in the forced expiratory volume in one second from before baseline) was significantly attenuated only by 150 mg of PY 108-068 compared to placebo (24 +/- 13 vs 40 +/- 16; p less than 0.05). Headache, which occurred in six subjects after nifedipine, five after 150 mg of PY 108-068, one after 75 mg of PY 108-068, and none after placebo, was subjectively more severe after nifedipine. We conclude that in these patients, there was a tendency for mild bronchodilation before exercise with both 150 mg of PY 108-068 and nifedipine, but only the 150-mg dose provided significant protection against exercise-induced asthma two hours after the drug.