Autoantibody-Targeted Treatments for Acute Exacerbations of Idiopathic Pulmonary Fibrosis

BACKGROUND

Severe acute exacerbations (AE) of idiopathic pulmonary fibrosis (IPF) are medically untreatable and often fatal within days. Recent evidence suggests autoantibodies may be involved in IPF progression. Autoantibody-mediated lung diseases are typically refractory to glucocorticoids and nonspecific medications, but frequently respond to focused autoantibody reduction treatments. We conducted a pilot trial to test the hypothesis that autoantibody-targeted therapies may also benefit AE-IPF patients.

METHODS

Eleven (11) critically-ill AE-IPF patients with no evidence of conventional autoimmune diseases were treated with therapeutic plasma exchanges (TPE) and rituximab, supplemented in later cases with intravenous immunoglobulin (IVIG). Plasma anti-epithelial (HEp-2) autoantibodies and matrix metalloproteinase-7 (MMP7) were evaluated by indirect immunofluorescence and ELISA, respectively. Outcomes among the trial subjects were compared to those of 20 historical control AE-IPF patients treated with conventional glucocorticoid therapy prior to this experimental trial.

RESULTS

Nine (9) trial subjects (82%) had improvements of pulmonary gas exchange after treatment, compared to one (5%) historical control. Two of the three trial subjects who relapsed after only five TPE responded again with additional TPE. The three latest subjects who responded to an augmented regimen of nine TPE plus rituximab plus IVIG have had sustained responses without relapses after 96-to-237 days. Anti-HEp-2 autoantibodies were present in trial subjects prior to therapy, and were reduced by TPE among those who responded to treatment. Conversely, plasma MMP7 levels were not systematically affected by therapy nor correlated with clinical responses. One-year survival of trial subjects was 46+15% vs. 0% among historical controls. No serious adverse events were attributable to the experimental medications.

CONCLUSION

This pilot trial indicates specific treatments that reduce autoantibodies might benefit some severely-ill AE-IPF patients. These findings have potential implications regarding mechanisms of IPF progression, and justify considerations for incremental trials of autoantibody-targeted therapies in AE-IPF patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01266317.

The many faces of Pulmonary Langerhans Cell Histiocytosis

Langerhans Cell Histiocytosis is a rare disease with variable presentation and prognosis in adults and in children. Histiocytosis of the ocular choroidal tissue has never been reported before in adults. We present two cases, one with choroidal involvement with asymptomatic nodulo-cystic changes in the lungs and another case with advanced single organ pulmonary involvement. We discuss the various treatment modalities and highlight the lack of adequate guidelines to treat adults. Most of the current guidelines are based on evidence derived from pediatric literature. We would also like to draw attention to the asymptomatic nature of the lung involvement and suggest that imaging of the lung be obtained in all cases of Langerhans Cell Histiocytosis.

Plasma B lymphocyte stimulator and B cell differentiation in idiopathic pulmonary fibrosis patients

We hypothesized B cells are involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF), a progressive, restrictive lung disease that is refractory to glucocorticoids and other nonspecific therapies, and almost invariably lethal. Accordingly, we sought to identify clinically associated B cell-related abnormalities in these patients. Phenotypes of circulating B cells were characterized by flow cytometry. Intrapulmonary processes were evaluated by immunohistochemistry. Plasma B lymphocyte stimulating factor (BLyS) was assayed by ELISA. Circulating B cells of IPF subjects were more Ag differentiated, with greater plasmablast proportions (3.1 ± 0.8%) than in normal controls (1.3 ± 0.3%) (p < 0.03), and the extent of this differentiation correlated with IPF patient lung volumes (r = 0.44, p < 0.03). CD20(+) B cell aggregates, diffuse parenchymal and perivascular immune complexes, and complement depositions were all prevalent in IPF lungs, but much less prominent or absent in normal lungs. Plasma concentrations of BLyS, an obligate factor for B cell survival and differentiation, were significantly greater (p < 0.0001) in 110 IPF (2.05 ± 0.05 ng/ml) than among 53 normal (1.40 ± 0.04 ng/ml) and 90 chronic obstructive pulmonary disease subjects (1.59 ± 0.05 ng/ml). BLyS levels were uniquely correlated among IPF patients with pulmonary artery pressures (r = 0.58, p < 0.0001). The 25% of IPF subjects with the greatest BLyS values also had diminished 1-y survival (46 ± 11%), compared with those with lesser BLyS concentrations (81 ± 5%) (hazard ratio = 4.0, 95% confidence interval = 1.8-8.7, p = 0.0002). Abnormalities of B cells and BLyS are common in IPF patients, and highly associated with disease manifestations and patient outcomes. These findings have implications regarding IPF pathogenesis and illuminate the potential for novel treatment regimens that specifically target B cells in patients with this lung disease.

Patients with idiopathic pulmonary fibrosis with antibodies to heat shock protein 70 have poor prognoses

RATIONALE

Diverse autoantibodies are present in most patients with idiopathic pulmonary fibrosis (IPF). We hypothesized that specific autoantibodies may associate with IPF manifestations.

OBJECTIVES

To identify clinically relevant, antigen-specific immune responses in patients with IPF.

METHODS

Autoantibodies were detected by immunoblots and ELISA. Intrapulmonary immune processes were evaluated by immunohistochemistry. Anti-heat shock protein 70 (HSP70) IgG was isolated from plasma by immunoaffinity. Flow cytometry was used for leukocyte functional studies.

MEASUREMENTS AND MAIN RESULTS

HSP70 was identified as a potential IPF autoantigen in discovery assays. Anti-HSP70 IgG autoantibodies were detected by immunoblots in 3% of 60 control subjects versus 25% of a cross-sectional IPF cohort (n = 122) (P = 0.0004), one-half the patients with IPF who died (P = 0.008), and 70% of those with acute exacerbations (P = 0.0005). Anti-HSP70 autoantibodies in patients with IPF were significantly associated with HLA allele biases, greater subsequent FVC reductions (P = 0.0004), and lesser 1-year survival (40 ± 10% vs. 80 ± 5%; hazard ratio = 4.2; 95% confidence interval, 2.0-8.6; P < 0.0001). HSP70 protein, antigen-antibody complexes, and complement were prevalent in IPF lungs. HSP70 protein was an autoantigen for IPF CD4 T cells, inducing lymphocyte proliferation (P = 0.004) and IL-4 production (P = 0.01). IPF anti-HSP70 autoantibodies activated monocytes (P = 0.009) and increased monocyte IL-8 production (P = 0.049). ELISA confirmed the association between anti-HSP70 autoreactivity and IPF outcome. Anti-HSP70 autoantibodies were also found in patients with other interstitial lung diseases but were not associated with their clinical progression.

CONCLUSIONS

Patients with IPF with anti-HSP70 autoantibodies have more near-term lung function deterioration and mortality. These findings suggest antigen-specific immunoassays could provide useful clinical information in individual patients with IPF and may have implications for understanding IPF progression.

Systemic delivery of atropine sulfate by the MicroDose Dry-Powder Inhaler

BACKGROUND

Inhaled atropine is being developed as a systemic and pulmonary treatment for the extended recovery period after chemical weapons exposure. We performed a pharmacokinetics study comparing inhaled atropine delivery using the MicroDose Therapeutx Dry Powder Inhaler (DPIA) with intramuscular (IM) atropine delivery via auto-injector (AUTO).

METHODS

The MicroDose DPIA utilizes a novel piezoelectric system to aerosolize drug and excipient from a foil dosing blister. Subjects inhaled a 1.95-mg atropine sulfate dose from the dry powder inhaler on one study day [5 doses × 0.4 mg per dose (nominal) delivered over 12 min] and received a 2-mg IM injection via the AtroPen® auto-injector on another. Pharmacokinetics, pharmacodynamic response, and safety were studied for 12 hr.

RESULTS

A total of 17 subjects were enrolled. All subjects completed IM dosing. One subject did not perform inhaled delivery due to a skin reaction from the IM dose. Pharmacokinetic results were as follows: area under the curve concentration, DPIA=20.1±5.8, AUTO=23.7±4.9 ng hr/mL (means±SD); maximum concentration reached, DPIA=7.7±3.5, AUTO=11.0±3.8 ng/mL; time to reach maximum concentration, DPIA=0.25±0.47, AUTO=0.19±0.23 hr. Pharmacodynamic results were as follows: maximum increase in heart rate, DPIA=18±12, AUTO=23±13 beats/min; average change in 1-sec forced expiratory volume at 30 min, DPIA=0.16±0.22 L, AUTO=0.11±0.29 L. The relative bioavailability for DPIA was 87% (based on output dose). Two subjects demonstrated allergic responses: one to the first dose (AUTO), which was mild and transient, and one to the second dose (DPIA), which was moderate in severity, required treatment with oral and intravenous (IV) diphenhydramine and IV steroids, and lasted more than 7 days.

CONCLUSIONS

Dry powder inhalation is a highly bioavailable route for attaining rapid and consistent systemic concentrations of atropine.

Acute respiratory distress syndrome: A clinical review

The acute respiratory distress syndrome (ARDS) is a complex disorder of heterogeneous etiologies characterized by a consistent, recognizable pattern of lung injury. Extensive epidemiologic studies and clinical intervention trials have been conducted to address the high mortality of this disorder and have provided significant insight into the complexity of studying new therapies for this condition. The existing clinical investigations in ARDS will be highlighted in this review. The limitations to current definitions, patient selection, and outcome assessment will be considered. While significant attention has been focused on the parenchymal injury that characterizes this disorder and the clinical support of gas exchange function, relatively limited focus has been directed to hemodynamic and pulmonary vascular dysfunction equally prominent in the disease. The limited available clinical information in this area will also be reviewed. The current standards for cardiopulmonary management of the condition will be outlined. Current gaps in our understanding of the clinical condition will be highlighted with the expectation that continued progress will contribute to a decline in disease mortality.

Basic ventilator management: lung protective strategies

Acute respiratory failure is manifested clinically as a patient with variable degrees of respiratory distress, but characteristically an abnormal arterial blood partial pressure of oxygen or carbon dioxide. The application of mechanical ventilation in this setting can be life-saving. An emerging body of clinical and basic research, however, has highlighted the potential adverse effects of positive pressure ventilation. Clinicians involved with the care of critically ill patients must recognize and seek to prevent these complications using lung-protective ventilation strategies. This article discusses the basic concepts of mechanical ventilation, reviews the categories of ventilator-associated lung injury, and discusses current strategies for the recognition and prevention of these adverse effects in the application of mechanical ventilation.

Effect of a second-generation venous catheter impregnated with chlorhexidine and silver sulfadiazine on central catheter-related infections: a randomized, controlled trial

BACKGROUND

Central venous catheter-related infections are a significant medical problem. Improved preventive measures are needed.

OBJECTIVE

To ascertain 1) effectiveness of a second-generation antiseptic-coated catheter in the prevention of microbial colonization and infection; 2) safety and tolerability of this device; 3) microbiology of infected catheters; and 4) propensity for the development of antiseptic resistance.

DESIGN

Multicenter, randomized, double-blind, controlled trial.

SETTING

9 university-affiliated medical centers.

PATIENTS

780 patients in intensive care units who required central venous catheterization.

INTERVENTION

Patients received either a standard catheter or a catheter coated with chlorhexidine and silver sulfadiazine.

MEASUREMENTS

The authors assessed catheter colonization and catheter-related infection, characterized microbes by molecular typing, and determined their susceptibility to antiseptics. Patient tolerance of the catheter was monitored.

RESULTS

Patients with the 2 types of catheters had similar demographic features, clinical interventions, laboratory values, and risk factors for infection. Antiseptic catheters were less likely to be colonized at the time of removal compared with control catheters (13.3 vs. 24.1 colonized catheters per 1000 catheter-days; P < 0.01). The center-stratified Cox regression hazard ratio for colonization controlling for sampling design and potentially confounding variables was 0.45 (95% CI, 0.25 to 0.78). The rate of definitive catheter-related bloodstream infection was 1.24 per 1000 catheter-days (CI, 0.26 to 3.62 per 1000 catheter-days) for the control group versus 0.42 per 1000 catheter-days (CI, 0.01 to 2.34 per 1000 catheter-days) for the antiseptic catheter group (P = 0.6). Coagulase-negative staphylococci and other gram-positive organisms were the most frequent microbes to colonize catheters. Noninfectious adverse events were similar in both groups. Antiseptic susceptibility was similar for microbes recovered from either group.

LIMITATIONS

The antiseptic catheter was not compared with an antibiotic-coated catheter, and no conclusion can be made regarding its effect on bloodstream infection.

CONCLUSIONS

The second-generation chlorhexidine-silver sulfadiazine catheter is well tolerated. Antiseptic coating appears to reduce microbial colonization of the catheter compared with an uncoated catheter.

Patients' recollections of stressful experiences while receiving prolonged mechanical ventilation in an intensive care unit

OBJECTIVE

To describe stressful experiences of adult patients who received mechanical ventilation for > or =48 hrs in an intensive care unit.

DESIGN

Prospective cohort study.

SETTING

Four intensive care units within an East Coast tertiary-care university medical center.

PATIENTS

Patients were 150 adult intensive care unit patients receiving mechanical ventilation for > or =48 hrs.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

As part of a study of the long-term outcomes of adult patients requiring prolonged mechanical ventilation, we used a 32-item questionnaire to collect data on patients' stressful experiences, both psychological (e.g., fearfulness, anxiety) and physical (e.g., pain, difficulty breathing), associated with the mechanical ventilation endotracheal tube and with being in an intensive care unit. Of 554 patients who met study criteria and survived prolonged mechanical ventilation, 150 consented and were oriented to person, place, and situation. Two thirds of these patients remembered the endotracheal tube and/or being in an intensive care unit. The median numbers of endotracheal tube and intensive care unit experiences remembered were 3 (of 7) and 9 (of 22), respectively. If a patient remembered an experience in the questionnaire, it was likely to be moderately to extremely bothersome. Some of the items that many patients found to be moderately to extremely bothersome were pain, fear, anxiety, lack of sleep, feeling tense, inability to speak/communicate, lack of control, nightmares, and loneliness. Stressful experiences associated with the endotracheal tube were strongly associated with subjects' experiencing spells of terror, feeling nervous when left alone, and poor sleeping patterns.

CONCLUSIONS

Subjects were more likely to remember experiences that were moderately to extremely bothersome. This might be because the more bothersome experiences were easier to recall or because most of these experiences are common and significant stressors to many of these patients. In either case, these data indicate that these patients are subject to numerous stressful experiences, which many find quite bothersome. This suggests the potential for improved symptom management, which could contribute to a less stressful intensive care unit stay and improved patient outcomes.

Analysis of antibody response to Cryptococcus neoformans in five patients with AIDS and cryptococcosis by immunoblotting

OBJECTIVES

The serological response of five patients with AIDS and cryptococcosis to non capsular antigens from Cryptococcus neoformans var. neoformans has been investigated.

METHODS

Pressates of different isolates of C. neoformans were used as antigenic preparation for immunoblotting of patient samples.

RESULTS

Multiple sera and cerebrospinal fluids sequentially collected from five AIDS patients with cryptococcosis showed a wide heterogeneity in antibody response with bands at 48. 43, 38 and 26 kD being present in all clinical samples of all five patients. The variation in banding patterns of the sequential samples from three patients was correlated with a decrease of the antigen titre and with an amelioration of the cryptococcal infection.

CONCLUSIONS

We identified antibodies to four immunodominant non-capsular antigens, which might represent major target molecules of the humoral response of patients with cryptococcosis.

Effect of enteral feeding with eicosapentaenoic acid, gamma-linolenic acid, and antioxidants in patients with acute respiratory distress syndrome. Enteral Nutrition in ARDS Study Group

OBJECTIVES

Recent studies in animal models of sepsis-induced acute respiratory distress syndrome (ARDS) have shown that a low-carbohydrate, high-fat diet combining the anti-inflammatory and vasodilatory properties of eicosapentaenoic acid (EPA; fish oil), gamma-linolenic acid (GLA; borage oil) (EPA+GLA), and antioxidants improves lung microvascular permeability, oxygenation, and cardiopulmonary function and reduces proinflammatory eicosanoid synthesis and lung inflammation. These findings suggest that enteral nutrition with EPA+GLA and antioxidants may reduce pulmonary inflammation and may improve oxygenation and clinical outcomes in patients with ARDS.

DESIGN

Prospective, multicentered, double-blind, randomized controlled trial.

SETTING

Intensive care units of five academic and teaching hospitals in the United States.

PATIENTS

We enrolled 146 patients with ARDS (as defined by the American-European Consensus Conference) caused by sepsis/pneumonia, trauma, or aspiration injury in the study.

INTERVENTIONS

Patients meeting entry criteria were randomized and continuously tube-fed either EPA+GLA or an isonitrogenous, isocaloric standard diet at a minimum caloric delivery of 75% of basal energy expenditure x 1.3 for at least 4-7 days.

MEASUREMENTS AND MAIN RESULTS

Arterial blood gases were measured, and ventilator settings were recorded at baseline and study days 4 and 7 to enable calculation of PaO2/FIO2, a measure of gas exchange. Pulmonary neutrophil recruitment was assessed by measuring the number of neutrophils and the total cell count in bronchoalveolar lavage fluid at the same time points. Clinical outcomes were recorded. Baseline characteristics of 98 evaluable patients revealed that key demographic, physiologic, and ventilatory variables were similar at entry between both groups. Multiple bronchoalveolar lavages revealed significant decreases (approximately 2.5-fold) in the number of total cells and neutrophils per mL of recovered lavage fluid during the study with EPA+GLA compared with patients fed the control diet. Significant improvements in oxygenation (PaO2/FIO2) from baseline to study days 4 and 7 with lower ventilation variables (FIO2, positive end-expiratory pressure, and minute ventilation) occurred in patients fed EPA+GLA compared with controls. Patients fed EPA+GLA required significantly fewer days of ventilatory support (11 vs. 16.3 days; p = .011), and had a decreased length of stay in the intensive care unit (12.8 vs. 17.5 days; p = .016) compared with controls. Only four of 51 (8%) patients fed EPA+GLA vs. 13 of 47 (28%) control patients developed a new organ failure during the study (p = .015).

CONCLUSIONS

The beneficial effects of the EPA+GLA diet on pulmonary neutrophil recruitment, gas exchange, requirement for mechanical ventilation, length of intensive care unit stay, and the reduction of new organ failures suggest that this enteral nutrition formula would be a useful adjuvant therapy in the clinical management of patients with or at risk of developing ARDS.

Nutritional aspects of lung disease

The relationships between dietary intake, ventilatory demand, and respiratory muscle function are now well recognized. Malnutrition in patients with advanced COPD is associated with adverse effects on respiratory muscle function leading to reduced muscle strength and premature mortality. The relationships between nutrient intake and the host inflammatory response are just beginning to be explored. This article summarizes current knowledge regarding the relationship between nutritional status and the lung.

Nutritional support in advanced lung disease. The pulmonary cachexia syndrome

Patients with advanced lung disease (ALD) demonstrate changes in body composition characteristically manifested by a progressive loss of body weight. The mechanisms of this pulmonary cachexia syndrome are multifactorial, and treatment must be comprehensive in nature. This article addresses our current knowledge regarding the relationship between nutrition and ALD.

Elevated TNF-alpha production by peripheral blood monocytes of weight-losing COPD patients

The inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta), have been associated with accelerated metabolism and protein turnover following exogenous administration in normal humans. We hypothesized that these inflammatory cytokines might contribute to the weight-losing process in patients with chronic obstructive pulmonary disease (COPD). COPD patients were identified prospectively as "weight losers" (WL; n = 10) if they reported > 5% weight loss during the preceding year or as "weight stable" (WS; n = 10) if their body weight fluctuated < or = 5%. Age-matched healthy volunteers were selected as the control group (C; n = 13). Monocytes were isolated from a peripheral blood sample, cultured, and exposed to lipopolysaccharide (LPS). The concentration of TNF-alpha and IL-1 beta in the monocyte supernatant was measured using a four layer enhanced ELISA. No significant difference in LPS-stimulated IL-1 beta production was found in the three study populations. However, LPS-stimulated TNF-alpha production (mean [range] ng/ml) by monocytes was significantly higher in the WL COPD patients (20.2 [6.3 to 44.8]), compared with WS patients (6.9 [1.5 to 16.6]), and C subjects (5.7 [0 to 61.8]). This difference was not maintained at 6 mo follow-up in the absence of ongoing weight loss. Definition of a causal relationship between TNF-alpha production and weight loss will require further understanding of the relationship between energy metabolism and TNF-alpha production in these patients.

Mechanisms of weight loss in chronic obstructive pulmonary disease

The COPD patient population is susceptible to the onset of weight loss. The presence of this feature carries significant negative prognostic implications. Whether weight loss contributes to or is simply a marker of disease severity remains to be determined. Weight loss appears to result from an imbalance of metabolic demand and supply. The factors which produce this imbalance require further investigation.

Indirect calorimetry with a hood: flow requirements, accuracy, and minute ventilation measurement

Flow-dilution-based hood systems for indirect calorimetry eliminate the conventional mouthpiece or mask of sealed-circuit systems allow measurements with improved patient comfort. This feature is particularly relevant when measurements are made over long periods of time or are repeated often. The flow of air pulled through the hood into the calorimeter in these systems is necessary to clear CO2 from inside the hood. The errors in these systems are greater than those in the sealed-circuit systems and are proportional to the flow. We show that the CO2 concentration within the hood at steady state does not depend on hood size. We describe the accuracy in determination of O2 consumption (VO2), CO2 production, and respiratory exchange ratio with a hood system as a function of the accuracy of the O2 and CO2 analyzers and the water vapor in collected gas. For example, we show that if there is a 1% error in O2 concentration, the percent error in VO2 changes from 5% in a sealed circuit to 51% when a cleansing flow of 50 l/min is introduced. The error in VO2 caused by a 5% error in CO2 determination is 10.6% at this cleansing flow. Removal of 90% of the water vapor (instead of 100%) before analysis of the expired gas introduces a 15.8% error in VO2. By use of the equations described, the accuracy of any measurement system can be determined. In addition, we demonstrate that the measurement of ventilation, usually lost in a hood system, can be preserved using dual pneumotachographs and a sealed hood.

Physiologic effects of oral supplemental feeding in malnourished patients with chronic obstructive pulmonary disease. A randomized control study

The association between severe nutritional depletion and chronic obstructive pulmonary disease (COPD) has long been recognized. A potential therapeutic benefit to nutritional support was previously suggested by us in a pilot investigation. Subsequent studies have reported conflicting results regarding the role of nutritional therapy in this clinical population. We report a randomized controlled study of nutritional therapy in underweight patients with COPD that combines an initial inpatient investigation (controlled nutritional support) with a prolonged outpatient follow-up interval. Provision of adequate calorie and protein support, adjusted to metabolic requirements, resulted in weight gain (intervention = +2.4 kg versus control -0.5 kg), improved handgrip strength (intervention = +5.5 kg-force versus control -6.0 kg-force), expiratory muscle strength (intervention = +14.9 cm H2O versus control -9.2 cm H2O), and walking distance (intervention = +429 feet versus control -1.0 foot). Inspiratory muscle strength was also improved (intervention = +11.4 cm H2O versus control +4.8 cm H2O) although this did not quite reach statistical significance. We conclude that provision of adequate nutrient supply under controlled conditions results in significant clinical improvements in the COPD patient population. However, the intervention is costly, time-intensive, and of limited therapeutic magnitude. More detailed work of alternative outpatient strategies combined with additional rehabilitative measures is indicated to delineate the full therapeutic potential of nutritional support for this clinical population.

Effects of growth hormone on diaphragmatic recovery from malnutrition

A 25% weight loss was induced in adult Fisher 344 rats by nutritional deprivation. Subsequently, normal feeding was resumed. Refed animals were divided into three groups and received recombinant human growth hormone (rhGH) injections during 5 wk of refeeding, saline injections during 5 wk of refeeding, or 9 wk of refeeding without injections. The effects of nutritional deprivation and the various refeeding protocols on the cross-sectional areas (CSA) of each of the four types of myofibers [typed immunohistochemically with antibodies against four myosin heavy chain (MHC) isoforms known to be present in the rat diaphragm] were determined. Malnutrition decreased the CSA of myofibers containing MHC2X, MHC2B, and MHC2A (i.e., fast myofibers), with the greatest effect on muscle mass being due to the atrophy of fibers containing MHC2X. Fibers containing MHC beta/slow failed to undergo malnutrition-induced atrophy. Whereas refeeding for 5 wk in the absence of rhGH allowed the recovery of CSA of fibers containing MHC2A, fibers containing MHC2B and MHC2X remained smaller than fibers of similar type in control animals. In contrast, 5 wk of refeeding supplemented with rhGH returned all fiber CSAs to control values. Even when refeeding alone was extended to 9 wk to allow for weight stabilization, the CSA of the fibers containing MHC2B and MHC2X remained smaller than similar fibers in control muscle. Serum insulin-like growth factor, a marker of malnutrition (R. Reeves and J. Elders, J. Nutr. 109: 613-620, 1979), was significantly decreased after nutritional deprivation and returned to normal after 5 wk of refeeding and GH supplementation.

Is loss of body weight in chronic obstructive pulmonary disease patients with emphysema secondary to low tissue oxygenation?

The available clinical information to date does not support the hypothesis that tissue oxygen debt is the primary cause of the wasting process in the chronic obstructive pulmonary disease (COPD) patient population. However, this should not deter the 'believers' of the hypothesis from further investigation. The information outlined above supports the need for reconsideration of this clinical problem. Tissue oxygen requirements and utilization is a complex interplay of multiple variables. Likewise, the assessment of nutritional status in the setting of oxygen therapy is complicated by shifts in body fluid compartments independent of changes in the fat-free mass (FFM). Utilization of newer techniques will be required to resolve the contribution of low tissue oxygenation to the wasting process. The continued development of noninvasive methods for the assessment of tissue metabolism, cardiac function, and tissue energy requirements will allow investigators to further clarify the relationship between tissue oxygenation and metabolism in patients with COPD. Clinical trials designed to examine this issue must recognize the multiple effects of oxygen on all aspects of nutrient utilization, including caloric intake, needs, and tissue delivery. Failure to address all aspects of this system will lead to continued debate regarding the etiology of weight loss in the COPD patient population.

Nutritional assessment and support in chronic obstructive pulmonary disease

Malnourished COPD patients demonstrate energy requirements significantly above predicted needs especially during activity. Recognition of this altered metabolic state is essential to the design of any nutritional intervention program. This factor alone, however, cannot explain the wasting syndrome observed in these patients. The elevated demands appear to combine with recognized factors which act to limit caloric intake. Nutritional repletion with calorie and protein supply proportional to demand is associated with weight gain, nitrogen retention, and improvement in physiologic parameters of muscle strength. Greater success of outpatient nutritional repletion in this population is dependent on alternative feeding strategies to deal with those symptoms which limit caloric intake, especially during a disease exacerbation. Future clinical research must explore these strategies before an adequate assessment of the risk and cost-benefit ratio of nutritional intervention can be determined. Additional work is indicated in techniques to identify those patients who would benefit from calorie supplementation as well as techniques to monitor the response of these individuals. Information gathered from the continued study of this population of stable outpatients with COPD will have wide application to the entire COPD patient population. This includes those patients with respiratory failure on mechanical ventilation, where numerous complicating factors makes the study of nutritional intervention and respiratory muscle function difficult.

Metabolic rate and weight loss in chronic obstructive lung disease

Although weight loss is a common problem in chronic obstructive pulmonary disease (COPD), the precise cause of malnutrition in COPD patients is not known. The purpose of this study was to measure and compare resting energy expenditure (REE) in stable undernourished and adequately nourished COPD. REE was measured in normal, adequately nourished, and undernourished COPD patients by indirect calorimetry and then compared to predicted basal metabolic rate (BMR) calculated from the Harris-Benedict equation. We found that measured REE, compared to predicted, was significantly higher in the undernourished group, (1.15 +/- 0.02) and compared to the adequately nourished COPD (0.99 +/- 0.03) and normal groups (0.93 +/- 0.02) (p less than 0.0001). We conclude that there is a hypermetabolic state in stable malnourished COPD patients which may be a factor in weight loss. This elevated REE also needs to be taken into account when determining caloric requirements for COPD patients.

Oxygen consumption of the respiratory muscles in normal and in malnourished patients with chronic obstructive pulmonary disease

Patients with severe chronic obstructive pulmonary disease (COPD) commonly experience weight loss. An increased energy expenditure for respiration might explain the increased caloric requirements and weight loss seen in this patient population. We measured the oxygen cost of augmenting ventilation (O2 cost) using an open circuit technique with dead-space stimulation of ventilation in nine normally nourished (greater than 90% ideal body weight) and in 10 malnourished (less than 90% ideal body weight) patients with COPD as well as in seven normal control subjects. O2 cost was significantly elevated in the malnourished patients with COPD (4.28 +/- 0.98 ml O2/L ventilation) relative to the normally nourished group (2.61 +/- 1.07) and the normal control subjects (1.23 +/- 0.51) (p less than 0.001). The measured resting energy expenditure (REEmeas) was also increased compared with predicted values (REEpred) in the malnourished population (REEmeas/REEpred = 94.57 +/- 6.21% for control subjects, 105.5 +/- 19.66% for normally nourished patients with COPD, and 119.4 +/- 11.69% for malnourished patients with COPD) (p less than 0.005). The malnourished population was characterized by a greater degree of hyperinflation (RV/TLC = 0.55 +/- 0.09 for normally nourished versus 0.69 +/- 0.06 for malnourished patients) and inspiratory muscle weakness (PImax = 51 +/- 16.5 for the normally nourished and 34 +/- 12.2 for the malnourished population). We conclude that malnourished patients with COPD are characterized by a relative increase in resting energy requirements and, specifically, increased energy requirements for augmenting ventilation. This increase in energy requirements may result from the increased mechanical work load associated with severe COPD and/or a reduced ventilatory muscle efficiency.

Use of beta-human chorionic gonadotropin in gestational aging

Quantitative radioimmunoassay (RIA) of the beta chain of human chorionic gonadotropin (B-hCG) in serum has been used to evaluate the gestational status of 99 normal early pregnancies in contrast to 29 ectopic, threatened, aborted and/or terminated cases. Quantitative measurement of serum B-hCG-RIA standardized against the second international standard (2dIS) accurately established age of normal pregnancies in utero up to but not after three weeks postconception and with an accuracy of plus or minus four days between the third and eighth week of gestation. Quantitative urinary hCG-RIA standardized against the 2dIS were not useful for gestational aging. Useful serum hCG-RIA were identically linear and parallel with the 2dIS, had negligible crossreactivity with LH, FSH and/or TSH, and had low nonspecific binding. Of 13 hCG-RIA evaluated, only assays having these latter characteristics were able to detect ectopic pregnancies, spontaneous abortions, and/or threatened pregnancies with up to 90 percent accuracy. However, some assays not standardized to the 2dIS gave over 200 percent error in hCG serum values. Thus, correct choice of quantitative B-hCG reagents is necessary for early pregnancy assessment.