Linoleic acid hydroperoxide: impaired bacterial uptake by alveolar macrophages, a mechanism of oxidant lung injury.

Exogenous linoleic acid hydroperoxide causes in vitro impairment of both bacterial uptake and the phagocytic stimulation of (14)CO(2) production from [1-(14)C]glucose in rabbit alveolar macrophages by an undefined effect on the cell membrane. This effect may be one mechanism for the defective pulmonary bacterial clearance characteristic of oxidant lung injury.

Asbestos: scientific developments and implications for public policy.

Asbestos is a commercial term for a group of fibrous minerals often associated with the development of pulmonary interstitial fibrosis (asbestosis), lung cancer, and malignant mesothelioma in occupationally exposed individuals. The pathogenicity of different forms of asbestos varies--long, thin amphibole fibers are most pathogenic, particularly in the induction of mesothelioma. Available data do not support the concept that low-level exposure to asbestos is a health hazard in buildings and schools. The concentration of asbestos fibers in air, type of asbestos, and size of fibers must be considered in evaluation of potential health risks.

Dissociation of bradycardia and arterial constriction during diving in the seal Phoca vitulina.

Bradycardia associated with diving in the harbor seal has been dissociated from the arterial constrictor response by intracardiac pacing. Development of arterial constriction does not depend upon the development of bradycardia. During pacing, arterial constriction continues in the absence of bradycardia. Increases in heart rate to values greater than 120 beats per minute during a dive produce a progressive decrease in mean aortic pressure, which suggests that one major function of bradycardia is to reduce cardiac output, thus matching left ventricular output to the restricted vascular bed and decreased venous return associated with diving.

Effect of SQ 14225, an inhibitor of angiotensin I-converting enzyme, on the granulomatous response to Schistosoma mansoni eggs in mice.

Murine schistosomiasis is a granulomatous disease associated with high serum and granuloma angiotensin I-converting enzyme (ACE) activity. SQ 14225, a specific competitive inhibitor of ACE, was administered to normal mice and mice infected with Schistosoma mansoni to determine whether this compound could inhibit granuloma ACE activity and modify the size of the granulomatous response to schistosome eggs. Peroral administration of SQ 14225 for 5 wk to infected mice with peak granulomatous responses decreased ACE activity in isolated liver granulomas. Treated mice demonstrated a decrease in granuloma size in the liver, colon, and ileum, and hydroxyproline concentration of isolated liver granulomas was increased. Mean diameters of synchronous pulmonary granulomas, induced by the pulmonary embolization of schistosome eggs into normal and sensitized mice, were decreased by a similar dose of SQ 14225. Withdrawal of SQ 14225 from unsensitized mice with 2-wk-old synchronous pulmonary granulomas induced an increase in inflammation. Infected, but not normal mice receiving SQ 14225 demonstrated reduced portal pressure, liver weight, and body weight. Both normal and infected mice experienced dipsogenesis, expanded intravascular volume, and increased serum ACE. These observations suggest that SQ 14225 can partially inhibit the granulomatous response to schistosome eggs and the pathological manifestations of schistosomiasis. It is possible that ACE has an inflammatory role in granulomatous inflammation.

Pulmonary mechanics during pregnancy.

Previously reported changes in static lung volumes during pregnancy have been confirmed. Measurements of lung compliance (C(L)) and total pulmonary resistance (R(L)) were made in 10 women in the last trimester of pregnancy and 2 months postpartum, employing an esophageal balloon and recording spirometer. C(L) was unaffected by pregnancy, but R(L) was 50% below normal during pregnancy. Measurements of airway conductance (C(A)) were made, employing the constant pressure body plethysmograph on 14 nonpregnant and 13 pregnant women. Specific airway conductance was increased during pregnancy. Serial measurements of C(A) indicated a progressive increase beginning at about 6 months of gestation and a return to normal by 2 months postpartum. The mechanism of the increased C(A) during pregnancy is not known. It may be related to changes in bronchial smooth muscle tone and conceivably explains the tolerance of certain patients with lung resections to pregnancy.

Glutathione-dependent peroxidative metabolism in the alveolar macrophage.

Phagocytosis by rabbit alveolar macrophages (AM) is accompanied by increases in O(2) consumption, glucose oxidation, and H(2)O(2) formation. Two aspects of the interrelations between these metabolic features of phagocytosis have been studied.First, the following evidence indicates that glutathione, glutathione reductase, and peroxidase serve as a cytoplasmic shuttle between H(2)O(2) and NADPH-dependent glucose oxidation: (a) AM contain 5.9 mmumoles of reduced glutathione per 10(6) cells and exhibit glutathione peroxidase and NADPH-specific glutathione reductase activity; (b) oxidized glutathione potentiates NADP stimulation of glucose oxidation; (c) an artificial H(2)O(2)-generating system stimulates glucose oxidation; (d) the cell penetrating thiol inhibitor, N-ethylmaleimide diminishes glucose oxidation. This effect largely depends on inhibition of the glutathione system rather than on inhibition of either H(2)O(2) formation or enzymes directly subserving glucose oxidation.Second, three potential H(2)O(2)-generating oxidases have been sought. No cyanide-insensitive NADH or NADPH oxidase activity could be detected. D-amino acid oxidase activity was 0.48 +/-0.07 U/10(6) cells with D-alanine as substrate.

Proteins of the cystic fibrosis respiratory tract. Fragmented immunoglobulin G opsonic antibody causing defective opsonophagocytosis.

In the disease cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a common clinical complication that determines most morbidity and almost all excess mortality. We postulated that in this disease a defect in Pseudomonas-reactive IgG antibodies may contribute to chronic Pseudomonas infections. Bronchoalveolar lavages were performed upon 13 patients with CF, 7 patients with chronic bronchitis characterized by recurrent Pseudomonas infections, and 4 normal volunteers. The levels of various proteins important to host defenses and proteases were determined; enzyme inhibition studies were performed. CF respiratory immunoglobulin levels were significantly elevated when compared with both normals and patients with chronic bronchitis (P less than 0.05). Albumin and transferrin levels were decreased in the CF lung fluids. CF elastolytic activity was strikingly elevated (means = 6.02 micrograms/mg total protein) and the inhibitory profile suggested such activity resembled a serine-proteinase. Alpha-1-antitrypsin antigenic levels were not altered in CF respiratory fluids. There was a tendency for the lavage IgG to fall as elastase levels rose (r = -0.29). IgG opsonins for two Pseudomonas immunotypes were isolated with affinity chromatography for functional and immunochemical studies. Bacterial phagocytic rates in the presence of these Pseudomonas-reactive IgG opsonins derived from CF lavage fluid were depressed (0.3% uptake/unit time) when compared with similarly titered positive controls (uptake = 1.3%/unit time, P less than 0.001). Additionally, normal pulmonary macrophage intracellular killing of Pseudomonas was severely altered in the presence of opsonins derived from CF respiratory fluids. At some time points, less than 30% of the bacteria were killed. CF IgG opsonins contain a cleavage fragment (100,000 D, 5S sedimentation coefficient) with antigenic determinants similar to the Fab portion of IgG. The presence of such a fragment was inversely correlated with phagocytic functional activity. Intact IgG comprised as little as 18% of the CF lavage fluid specimens. Aliquots of intact human IgG, when mixed with the CF opsonins, augmented Pseudomonas uptake and improved intracellular killing. Conversely, peptide fragments of IgG opsonins, which are proteolytically derived in vitro, duplicated in our system the defect observed with opsonins derived from CF lung fluids; bacterial uptake was inversely related to the concentration of F(ab')2 and to a greater degree, to Fc present in the opsonic mixture. We concluded that IgG respiratory opsonins are fragmented, inhibiting phagocytosis and serving a permissive role in the chronic Pseudomonas pulmonary infection in the disease CF.

The determination of total body exchangeable O2 stores.

A method is described for the measurement of total body exchangeable oxygen stores (TBO(2)). It is based on the dilution of the stable oxygen isotope, (18)O(2), by the body exchangeable oxygen stores under circumstances in which (18)O(2) steady-state equilibrium was evaluated simultaneously for both arterial and venous blood compartments. After evaluation of several simplifying assumptions, TBO(2) values in dog, normal man, and anemic patients were measured. The magnitude of the exchangeable nonlung oxygen stores was 11.0 +/- 3.1 ml/kg (SD) in 5 dogs, 11.9 +/- 2.1 ml/kg in 10 normal subjects, and 7.0 +/- 1.6 ml/kg in 8 patients with severe anemia (hematocrits of 25% or less).

Catalase-dependent peroxidative metabolism in the alveolar macrophage during phagocytosis.

EVIDENCE FOR THE PRESENCE OF PEROXIDATIVE METABOLISM IN RABBIT ALVEOLAR MACROPHAGES (AM) HAS BEEN OBTAINED FROM THE FOLLOWING OBSERVATIONS: (a) catalase is present in high concentrations; (b) peroxidase activity could not be detected employing guaiacol as substrate; (c) the irreversible inhibition of AM catalase by aminotriazole served as a detection system for H(2)O(2) and demonstrated increased intracellular H(2)O(2) after phagocytosis; (d) formate oxidation, a marker of catalase-dependent peroxidations, occurs in resting AM and is increased by phagocytosis; (c) measurements of H(2)O(2) accumulation in a dialysate of AM demonstrated twofold increase during phagocytosis; and (f) aminotriazole diminishes O(2) utilization and (14)CO(2) production from labelled glucose and pyruvate. It is concluded that, while catalase-dependent H(2)O(2) metabolism is not essential for particle entry, this pathway represents one of the metabolic pathways stimulated by particle entry in the AM.

Progressive immune failure in dyskeratosis congenita. Report of an adult in whom Pneumocystis carinii and fatal disseminated candidiasis developed.

Community-acquired Pneumocystis carinii pneumonia developed in a young adult patient with dyskeratosis congenita. His hospitalization ended fatally with disseminated candidiasis. Evaluation during the admission showed evidence of cellular immune dysfunction as indicated by skin test anergy and absent lymphocyte proliferation in an in vitro mixed lymphocyte culture. Treatment with transfer factor failed to reverse the cutaneous anergy or affect the clinical course. Dyskeratosis congenita is a rare multisystem disorder with prominent dermatologic manifestations; bone marrow failure or malignant neoplasm are common fatal outcomes. Immune system abnormalities are not classically considered a part of the disease complex. Serial evaluation of our patient's condition over several years suggests that depressed immune function, especially of the cellular limb, may evolve as a feature of clinical importance in these patients.

The clinical assessment of roentgenographically atypical pulmonary sarcoidosis.

We studied 89 patients in whom the clinical diagnosis of sarcoidosis was supported by the findings on tissue biopsy. A chest roentgenogram in 14 of the patients showed one of the following atypical features: large pulmonary nodules, an alveolar parenchymal pattern or a pleural effusion. Diagnoses of infection, malignancy or vasculitis were suggested by interpretations of atypical chest roentgenograms in eight of these 14 patients. Nonspecific and misleading clinical information contributed. The diagnosis of sarcoidosis was corroborated by extrathoracic tissue biopsies in 11 of the 14 patients. Over an average observation period of 38 months, the 14 patients remained classified as having sarcoidosis. This suggests that an extrathoracic tissue biopsy, whose findings are consistent with sarcoidosis, is often sufficient to support a clinical diagnosis of some forms of roentgenographically atypical pulmonary sarcoidosis.

Vegetable dust and airway disease: inflammatory mechanisms.

Exposure to cotton or grain dust causes an obstructive bronchitis in certain subjects, mechanisms of which are poorly understood. A difficulty encountered in discerning mechanisms of this airway disease is the lack of knowledge of the active components of these dusts. Clinical features suggest common but not exact mechanisms of the airway disease associated with these vegetable dusts. Human and animal studies show evidence of acellular and cellular inflammatory mechanisms of the bronchoconstriction and inflammation associated with these disorders. Potential cellular sources include alveolar macrophages, polymorphonuclear leukocytes, mast cells, basophils, eosinophils and lymphocytes. Acellular origins include the complement and humoral antibody systems, both of which have been implicated, although their pathogenic role in grain or cotton dust disorders is uncertain. In this review we critically address potential inflammatory mechanisms of airway alterations resulting from cotton or grain dust exposure. General mechanisms of bronchoconstriction are first presented, then specific studies dealing with either of the two dusts are discussed. We believe this area of research may be fruitful in dissecting mechanisms of bronchoconstriction and airway inflammation, especially as more human studies are undertaken.

Diaphragm pacing. Application to a patient with chronic obstructive pulmonary disease.

In a 66-year-old patient with chronic obstructive pulmonary disease (COPD) complicated by arterial hypoxemia and repeated episodes of respiratory and right ventricular failure, a satisfactory level of oxygenation could not be maintained despite controlled oxygen therapy. To enable oxygen to be administered without depression ventilation, artificial respiration by means of phrenic nerve stimulation (diaphragm pacing) has been employed. Evidence of clinical improvement since pacing was begun 32 months ago include fewer episodes of respiratory failure and better control of congestive heart failure despite a gradual worsening of pulmonary function.

Pulmonary granulomas in a patient with pulmonary veno-occlusive disease.

A patient with pulmonary veno-occlusive disease is described. Lung biopsy revealed noncaseating granulomas in conjunction with the typical vascular changes of this entity. This concurrence has not been previously described.

Tantalum oxide and alveolar macrophage function.

The alveolar macrophage (AM) has been cited as a potential source for clearing tantalum from the lungs following bronchography. We studied the short term effects of tantalum oxide on rabbit AM viability and metabolism in vitro. AM phagocytosed tantalum oxide particles without cytotoxicity and with a significant rise in glucoxe oxidation. These results suggest that the AM represents an important vehicle for clearance of tantalum particles from airways in vivo.

Tantalum oxide, silica and latex: effects on alveolar macrophage viability and lysozyme release.

Tantalum an experimental bronchographic material, may be retained in the lungs for a prolonged period following bronchography. The alveolar macrophage (AM) is a cell with potential for clearing tantalum particles from the airways. We studied the in vitro effects of tantalum oxide and two other particles, silca and latex, on rabbit AM viability and lysozyme release over 30 hours. Results indicate: 1) tantalum oxide, silica, and latex particles are ingested by rabbit AM in culture; 2) tantalum oxide and silica are both toxic to AM in vitro; and 3) tantalum oxide exerts its toxic effects less rapidly on AM than does silica. On the basis of these in vitro culture results we conclude that tantalum oxide may be toxic to alveolar macrophages in vivo. Delayed lung clearance of tantalum oxide particles may be due in part to their toxic effects on alveolar macrophages.

Exercise testing in occupational lung diseases.

The authors discuss the value of exercise testing in two areas of importance in occupational pulmonary disease: (1) the surveillance of worker populations in order to gain epidemiologic and physiologic understanding of disease and (2) the assessment of work capacity in individual patients.

Pregnancy-induced hypertension and reduced intraventricular hemorrhage in preterm infants.

Increasing evidence suggests that the incidence of periventricular intraventricular hemorrhage (PV-IVH) is lower in infants born to mothers with pregnancy-induced hypertension (PIH). The mechanism or mechanisms accounting for this reduction remain unclear but may be related to PIH itself, medications used to treat the mother (e.g., magnesium sulfate), or to obstetrical management. In this retrospective analysis, we determined the incidence of PV-IVH in singleton preterm infants weighing less than 1,500 gm born to mothers with PIH who were also administered magnesium sulfate. Between January 1988 and December 1994, 254 singleton infants born to mothers with PIH and 1,083 born to mothers without PIH were studied. PV-IVH developed in 360 (26.9%) of the 1,337 infants; 977 (74.1%) infants did not exhibit PV-IVH. The incidence of total as well as severe PV-IVH was lower in infants born to mothers with PIH than in those without PIH [i.e., 16% vs 30% (total) and 8.2% vs 14.5% (severe), P < .001] with an odds ratio (OR) estimate of 0.43 [95% confidence interval (CI) 0.30, 0.61]. Infants born to mothers with PIH weighed more, (1,152 +/- 250 gm vs 1,058 +/- 283 gm, P < .001) and were more mature (30.1 +/- 2.9 vs 27.7 +/- 31 weeks, P < .001) than infants born to mothers without PIH. These infants were also less likely to be exposed to labor (57% vs 93%), to be delivered by cesarean section (81% vs 35%), and to require intubation (49% vs 58%), but more likely to exhibit respiratory distress syndrome (RDS) (47% vs 38%, P < .01). By logistic regression analysis, after seven variables (i.e., PIH, gestational age, and birthweight, both modeled as cubic polynomials; labor; intubation; RDS; and race) were included in the analytic model, PIH remained a significant predictor of IVH: P = .006, OR = 0.54 (95% CI 0.349, 0.847). These data indicate a significantly lower incidence of PV-IVH of approximately 50% in infants born to mothers with PIH as compared with the incidence in infants born to mothers without PIH, despite their higher incidence of RDS. The reduction in PV-IVH may be directly related to the PIH; however, the independent role of antenatal magnesium sulfate administration requires further study.

Hypermagnesemia does not increase brain intracellular magnesium in newborn swine.

Phosphorus-31 magnetic resonance spectroscopy was used in 2-day (n = 4) and 40-day (n = 4) miniswine to determine whether plasma hypermagnesemia alters brain intracellular magnesium concentration and if the plasma-brain intracellular magnesium relationship changes with age. At control, brain intracellular magnesium concentration was similar in the 2-day (0.24 +/- 0.04 mM) and 40-day groups (0.21 +/- 0.01 mM). Intravenous infusions of magnesium sulfate (MgSO(4), 60 minute) raised plasma magnesium concentration to 4-6 mM in both groups. During and for 3 hours after MgSO(4) infusions, there were no changes in brain intracellular magnesium concentration in either group and no correlation between plasma and brain intracellular magnesium (r = 0.11 and 0.08 for 2- and 40-day groups, respectively). Brain intracellular magnesium concentration appears to be tightly regulated.

Silica, silicosis, and lung cancer: a response to a recent working group report.

The relationship between crystalline silica and lung cancer has been the subject of many recent publications, conferences, and regulatory considerations. An influential, international body has determined that there was sufficient evidence to conclude that quartz and cristobalite are carcinogenic in humans. The present authors believe that the results of these studies are inconsistent and, when positive, only weakly positive. Other, methodologically strong, negative studies have not been considered, and several studies viewed as providing evidence supporting the carcinogenicity of silica have significant methodological weaknesses. Silica is not directly genotoxic and is a pulmonary carcinogen only in the rat, a species that seems to be inappropriate for assessing particulate carcinogenesis in humans. Data on humans demonstrate a lack of association between lung cancer and exposure to crystalline silica. Exposure-response relationships have generally not been found. Studies in which silicotic patients were not identified from compensation registries and in which enumeration was complete did not support a causal association between silicosis and lung cancer, which further argues against the carcinogenicity of crystalline silica.