Elastin degradation products in acute lung injury induced by gastric contents aspiration.

BACKGROUND: Gastric contents aspiration is a high-risk condition for acute lung injury (ALI). Consequences range from subclinical pneumonitis to respiratory failure, depending on the volume of aspirate. A large increment in inflammatory cells, an important source of elastase, potentially capable of damaging lung tissue, has been described in experimental models of aspiration. We hypothesized that in early stages of aspiration-induced ALI, there is proteolytic degradation of elastin, preceding collagen deposition. Our aim was to evaluate whether after a single orotracheal instillation of gastric fluid, there is evidence of elastin degradation. METHODS: Anesthesized Sprague-Dawley rats received a single orotracheal instillation of gastric fluid and were euthanized 4, 12 and 24 h and at day 4 after instillation (n = 6/group). We used immunodetection of soluble elastin in lung tissue and BALF and correlated BALF levels of elastin degradation products with markers of ALI. We investigated possible factors involved in elastin degradation and evaluated whether a similar pattern of elastin degradation can be found in BALF samples of patients with interstitial lung diseases known to have aspirated. Non-parametric ANOVA (Kruskall-Wallis) and linear regression analysis were used. RESULTS: We found evidence of early proteolytic degradation of lung elastin. Elastin degradation products are detected both in lung tissue and BALF in the first 24 h and are significantly reduced at day 4. They correlate significantly with ALI markers, particularly PMN cell count, are independent of acidity and have a similar molecular weight as those obtained using pancreatic elastase. Evaluation of BALF from patients revealed the presence of elastin degradation products not present in controls that are similar to those found in BALF of rats treated with gastric fluid. CONCLUSIONS: A single instillation of gastric fluid into the lungs induces early proteolytic degradation of elastin, in relation to the magnitude of alveolar-capillary barrier derangement. PMN-derived proteases released during ALI are mostly responsible for this damage. BALF from patients showed elastin degradation products similar to those found in rats treated with gastric fluid. Long-lasting effects on lung elastic properties could be expected under conditions of repeated instillations of gastric fluid in experimental animals or repeated aspiration events in humans.

47-Fold rise of diabetes in childbearing age Chilean women: Markov model and cost-effectiveness of prevention of birth defects.

AIM: Prevalence of type 2 diabetes mellitus (T2DM) during childbearing age in Chile had a 47-fold rise in 7 years, reaching 120 844 women, half of which are unaware of their condition. We aimed to project pregnancies and births among Chilean women of childbearing age (WCBA) with T2DM and report the incidence of birth defects and the associated years of life lost and lifetime costs. METHODS: Markov model of cohort of WCBA with T2DM (WCBA-DM) with a 20-year time horizon (2018-2037), using data from previous studies. Two scenarios were assessed: scenario A: no universal detection of T2DM and scenario B: universal screening of T2DM using glycosylated hemoglobin levels. Both lifetime costs and disability-adjusted life years (DALY) were calculated with a 5% discount rate (US$ of 2017). RESULTS: In scenario A, 12 163 infants with birth defects could be born among the analyzed cohort, resulting in 243 260 years of life lost, 296 652 DALY and in lifetime costs of US$ 1 957 657 966. In scenario B, the first three figures could be reduced by 70.4% to 3599 infants with birth defects, 71 980 years of life lost and 87 794 DALY. Due to the addition of diabetes screening and new patient costs to scenario B, there would be a lesser reduction (67.3%) in total lifetime costs, to US$ 640 669 296. CONCLUSION: Screening of diabetes in WCBA would yield a 20-year reduction of 70.4% in the number of infants with birth defects, years of life lost and DALY. Total lifetime costs could be reduced by 67.3%.

Changes in the pattern of fibrosis in the rat lung with repetitive orotracheal instillations of gastric contents: evidence of persistent collagen accumulation.

Recurrent aspiration of gastric contents has been associated with several interstitial lung diseases. Despite this association, the pathogenic role of aspiration in these diseases has been poorly studied and little is known about extracellular matrix (ECM) changes in animal models of repetitive events of aspiration. Our aim was to study the repair phase of lung injury induced by each of several instillations of gastric fluid in Sprague-Dawley rats to evaluate changes in ECM and their reversibility. Anesthetized animals received weekly orotracheal instillations of gastric fluid for 1, 2, 3, and 4 wk and were euthanized at day 7 after last instillation. For reversibility studies, another group received 7 weekly instillations and was euthanized at day 7 or 60 after last instillation. Biochemical and histological measurements were used to evaluate ECM changes. Lung hydroxyproline content increased progressively and hematoxylin and eosin, Masson's trichrome, and alpha-SMA stains showed that after a single instillation, intra-alveolar fibrosis predominated, whereas with repetitive instillations this fibrosis pattern became less prominent and interstitial fibrosis progressively became evident. Both type I and III collagen increased in intra-alveolar and interstitial fibrosis. Imbalance between matrix metalloproteinase-2 (MMP-2) activity and tissue inhibitor of metalloproteinase-2 (TIMP-2) expression was observed, favoring either collagen degradation or accumulation depending on the number of instillations. Caspase-3 activation was also dose dependent. ECM changes were partially reversible at long-term evaluation, since Masson bodies, granulomas, and foreign body giant cells disappeared, whereas interstitial collagen accumulated. In conclusion, repetitive lung instillations of gastric fluid induce progressive fibrotic changes in rat lung ECM that persist at long-term evaluation.

Acute lung injury by gastric fluid instillation: activation of myofibroblast apoptosis during injury resolution.

BACKGROUND: Gastric contents aspiration in humans has variable consequences depending on the volume of aspirate, ranging from subclinical pneumonitis to respiratory failure with up to 70% mortality. Several experimental approaches have been used to study this condition. In a model of single orotracheal instillation of gastric fluid we have shown that severe acute lung injury evolves from a pattern of diffuse alveolar damage to one of organizing pneumonia (OP), that later resolves leaving normal lung architecture. Little is known about mechanisms of injury resolution after a single aspiration that could be dysregulated with repetitive aspirations. We hypothesized that, in a similar way to cutaneous wound healing, apoptosis may participate in lung injury resolution by reducing the number of myofibroblasts and by affecting the balance between proteases and antiproteases. Our aim was to study activation of apoptosis as well as MMP-2/TIMP-2 balance in the sub-acute phase (4-14 days) of gastric fluid-induced lung injury. METHODS: Anesthesized Sprague-Dawley rats received a single orotracheal instillation of gastric fluid and were euthanized 4, 7 and 14 days later (n = 6/group). In lung tissue we studied caspase-3 activation and its location by double immunofluorescence for cleaved caspase-3 or TUNEL and alpha-SMA. MMP-2/TIMP-2 balance was studied by zymography and Western blot. BALF levels of TGF-ß1 were measured by ELISA. RESULTS: An OP pattern with Masson bodies and granulomas was seen at days 4 and 7 that was no longer present at day 14. Cleaved caspase-3 increased at day 7 and was detected by immunofluorescence in Masson body-alpha-SMA-positive and -negative cells. TUNEL-positive cells at days 4 and 7 were located mainly in Masson bodies. Distribution of cleaved caspase-3 and TUNEL-positive cells at day 14 was similar to that in controls. At the peak of apoptosis (day 7), an imbalance between MMP-2 activity and TIMP-2 expression was produced by reduction in TIMP-2 expression. CONCLUSIONS: Apoptosis is activated in Masson body-alpha-SMA-positive and -negative cells during the sub-acute phase of gastric fluid-induced lung injury. This mechanism likely contributes to OP resolution, by reducing myofibroblast number and new collagen production. In addition, pre-formed collagen degradation is favored by an associated MMP-2/TIMP-2 imbalance.

Basal-bolus insulin therapy reduces maternal triglycerides in gestational diabetes without modifying cholesteryl ester transfer protein activity.

AIM: Macrosomia in the offspring of overweight/obese mothers with glucose-controlled gestational diabetes mellitus (GDM) is due to excessive rise of maternal triglycerides (TG). We aimed to ascertain whether basal-bolus insulin therapy (BBIT), or other components of the treatment, could reduce TG in GDM. METHODS: We studied the records of 131 singleton pregnancies with GDM, using stepwise multiple linear regression, Mann-Whitney, χ2 , and Jonckheere-Terpstra tests. As maternal TG increased steadily during normal pregnancy, these were transformed as z-scores. The atherogenic index of plasma (AIP) was calculated as a measure of cholesteryl ester transfer protein activity. RESULTS: Multiple regression showed that only BBIT (but neither limitation of weight gain nor metformin) reduced maternal TG z-scores (P = 0.011). When the 131 pregnancies were split into two groups - without BBIT (n = 58; HbA1c = 5.3 ± 0.3%) and with BBIT (n = 73; HbA1c = 5.4 ± 0.6; P = 0.2005) - we observed that BBIT (n = 73) reduced maternal TG z-scores in a dose-related fashion (Jonckheere-Terpstra P = 0.03817). The atherogenic index of plasma remained within normal range in both groups. CONCLUSION: BBIT (but not weight gain control nor metformin) reduced maternal TG in mothers with glucose-controlled GDM. This beneficial effect of BBIT was not related to changes in the cholesteryl ester transfer protein activity.

Acute lung injury induced by whole gastric fluid: hepatic acute phase response contributes to increase lung antiprotease protection.

BACKGROUND: Gastric contents aspiration in humans is a risk factor for severe respiratory failure with elevated mortality. Although aspiration-induced local lung inflammation has been studied in animal models, little is known about extrapulmonary effects of aspiration. We investigated whether a single orotracheal instillation of whole gastric fluid elicits a liver acute phase response and if this response contributes to enrich the alveolar spaces with proteins having antiprotease activity. METHODS: In anesthetized Sprague-Dawley rats receiving whole gastric fluid, we studied at different times after instillation (4 h -7 days): changes in blood cytokines and acute phase proteins (fibrinogen and the antiproteases alpha1-antitrypsin and alpha2-macroglobulin) as well as liver mRNA expression of the two antiproteases. The impact of the systemic changes on lung antiprotease defense was evaluated by measuring levels and bioactivity of antiproteases in broncho-alveolar lavage fluid (BALF). Markers of alveolar-capillary barrier derangement were also studied. Non-parametric ANOVA (Kruskall-Wallis) and linear regression analysis were used. RESULTS: Severe peribronchiolar injury involving edema, intra-alveolar proteinaceous debris, hemorrhage and PMNn cell infiltration was seen in the first 24 h and later resolved. Despite a large increase in several lung cytokines, only IL-6 was found elevated in blood, preceding increased liver expression and blood concentration of both antiproteases. These changes, with an acute phase response profile, were significantly larger for alpha2-macroglobulin (40-fold increment in expression with 12-fold elevation in blood protein concentration) than for alpha1-antitrypsin (2-3 fold increment in expression with 0.5-fold elevation in blood protein concentration). Both the increment in capillary-alveolar antiprotease concentration gradient due to increased antiprotease liver synthesis and a timely-associated derangement of the alveolar-capillary barrier induced by aspiration, contributed a 58-fold and a 190-fold increase in BALF alpha1-antitrypsin and alpha2-macroglobulin levels respectively (p < 0.001). CONCLUSIONS: Gastric contents-induced acute lung injury elicits a liver acute phase response characterized by increased mRNA expression of antiproteases and elevation of blood antiprotease concentrations. Hepatic changes act in concert with derangement of the alveolar capillary barrier to enrich alveolar spaces with antiproteases. These findings may have significant implications decreasing protease burden, limiting injury in this and other models of acute lung injury and likely, in recurrent aspiration.

Resolution of lung injury after a single event of aspiration: a model of bilateral instillation of whole gastric fluid.

Gastric aspiration is a high-risk condition for lung injury. Consequences range from subclinical pneumonitis to respiratory failure, with fibrosis development in some patients. Little is known about how the lung repairs aspiration-induced injury. By using a rat model of single orotracheal instillation of whole gastric contents, we studied the time course of morphological and biochemical changes during injury and resolution, and evaluated whether repair involved long-term fibrosis. Anesthetized rats received one gastric fluid instillation. At 4, 12, and 24 hours and 4 and 7 days, we performed lung histological studies and biochemical measurements in bronchoalveolar lavage fluid and lung tissue. Physiological measurements were performed at 12 to 24 hours. Long-term outcome was studied histologically at day 60. During the first 24 hours, severe peribronchiolar injury involving edema, intra-alveolar proteinaceous debris, hemorrhage, increased neutrophils and cytokines, and physiological dysfunction were observed. At days 4 and 7, an organizing pneumonia (OP) pattern developed, with foreign-body giant cells and granulomas. Lung matrix metalloproteinase 9 and 2 activities increased, with metalloproteinase-9 linked to early inflammation and metalloproteinase-2 to OP. At day 60, lung architecture was normal. In conclusion, a continuum of alterations starting with severe injury, evolving toward OP and later resolving, characterizes the rat single aspiration event. In addition to identifying markers of staging and severity, this model reveals that OP participates in the repair of aspiration-induced injury.

Preventive letter: doubling the return rate after gestational diabetes mellitus.

To measure the impact of a "Preventive Letter" designed to encourage the return of gestational diabetes mellitus (GDM) mothers to follow up visit after delivery, in the context of a worldwide concern about low return rates after delivery of these patients. Mothers with GDM require medical evaluation and an oral glucose tolerance test (OGTT) 6 weeks after delivery, in order to: [a] confirm remission of GDM and [b] provide advice on the prevention of type 2 diabetes. In the year 2003 we developed a "Preventive Letter", containing three aspects: [a] current treatment, [b] suggested management during labor, and [c] a stapled laboratory order for OGTT to be performed 6 weeks after delivery. The return rate after delivery was assessed in two groups of GDM mothers: [a] "Without Preventive Letter" (n = 253), and "With Preventive Letter" (n = 215). Both groups, similar with respect to age (33.0 ± 5.4 and 32.3 ± 4.9 years respectively, p = 0.166) and education time (14.9 ± 1.8 and 15.0 ± 1.8 years respectively, p = 0.494), showed a significant difference in the 1-year return rate after delivery, as assessed by the Kaplan-Meier test: 32.0 % for the group "Without Preventive Letter", and 76.0 % for the group "With Preventive Letter" (p < 0.001). The 1-year return rate after delivery of GDM mothers was 2.4 times higher in the group "With Preventive Letter" than in the group without it. We believe that this low-cost approach could be useful in other institutions caring for pregnant women with diabetes.

Maternal hypertriglyceridemia: A link between maternal overweight-obesity and macrosomia in gestational diabetes.

OBJECTIVE: Infants born from overweight and obese mothers with glucose-controlled gestational diabetes (GDM) tend to be large-for-gestational age (LGA). It is hypothesized that this is due to an excessive rise in maternal triglyceride levels. METHODS: Two-hundred and seventy nine singleton GDM pregnancies were divided into three groups according to prepregnancy BMI: normal weight (BMI = 20-24.9; n = 128), overweight (BMI = 25-29.9; n = 105), and obese (BMI ≥ 30; n = 46). Individual z-scores (ZS) of maternal triglycerides and of newborn weight (NWZS) were calculated as deviations from published 50th percentiles. Mean z-scores (MZS) were the average of triglyceride ZSs. MZS of triglycerides, HbA1c and NWZS were compared. Variables are expressed as mean ± SD. RESULTS: In the three groups respectively: LGA (%) = 10.1%, 19.0% and 30.4% (P = 0.015). Birth weight (g) = 3274.2 ± 501.3, 3342.4 ± 620.2 and 3366.3±644.7 (RSPEARMAN = 0.111, P = 0.027). HbA1c (%) = 5.2 ± 0.39, 5.3 ± 0.50 and 5.4 ± 0.47 (P = NS). Triglyceride MZS = 1.20 ± 1.13, 1.52 ± 1.37 and 1.62 ± 1.42 (RSPEARMAN = 0.116, P = 0.024). Correlations between triglyceride MZS and NWZS were, respectively: r = 0.12 (P = NS), r = 0.42 (P <0.001), and r = 0.47 (P < 0.001). CONCLUSIONS: In overweight and obese GDM mothers, maternal triglycerides are partially responsible for LGA infants despite good maternal glucose control during pregnancy.

Gestational diabetes and pre-pregnancy overweight: possible factors involved in newborn macrosomia.

AIM: Good glycemic control in gestational diabetes mellitus (GDM) seems not to be enough to prevent macrosomia (large-for-gestational-age newborns). In GDM pregnancies we studied the effects of glycemic control (as glycosylated hemoglobin [HbA1c]), pre-pregnancy body mass index (PP-BMI) and gestational weight gain per week (GWG-W) on the frequency of macrosomia. METHODS: We studied 251 GDM pregnancies, divided into two groups: PP-BMI<25.0kg/m(2) (the non-overweight group; n=125), and PP-BMI≥25.0kg/m(2) (the overweight group; n=126). A newborn weight Z-score>1.28 was considered large-for-gestational-age. Statistical analysis was carried out using the Student's t-test and χ(2) -test, receiver-operator characteristic curves and linear and binary logistic regressions. RESULTS: Prevalence of macrosomia was 14.9% among GDM (n=202/251, 88.4%) with good glycemic control (mean HbA1c<6.0%), and 28.1% in those with mean HbA1c≥6.0% (n=49/251, P<0.025). Macrosomia rates were 10.4% in the non-overweight group and 24.6% in the overweight group (P=0.00308), notwithstanding both having similar mean HbA1c (5.48±0.065 and 5.65±0.079%, P=0.269), and similar GWG-W (0.292±0.017 and 0.240±0.021kg/week, P=0.077). Binary logistic regressions showed that PP-BMI (P=0.012) and mean HbA1c (P=0.048), but not GWG-W (P=0.477), explained macrosomia. CONCLUSIONS: Good glycemic control in GDM patients was not enough to reduce macrosomia to acceptable limits (<10% of newborns). PP-BMI and mean HbA1c (but not GWG-W) were significant predictors of macrosomia. Thus, without ceasing in our efforts to improve glycemic control during GDM pregnancies, patients with overweight/obesity need to be treated prior to becoming pregnant.

Mitochondrial diabetes and deafness: possible dysfunction of strial marginal cells of the inner ear.

OBJECTIVE: Some patients with the syndrome of mitochondrial diabetes and deafness (MIDD) have a m.3243A>G mutation of the MTTL1 gene encoding transfer ribonucleic acid for the amino acid leucine (tRNALeu(UUR)). One of our MIDD patients inspired us to propose an integrated view on how a single mutation of the mitochondrial deoxyribonucleic acid (DNA) affects both the glucose metabolism and the inner ear physiology. DESIGN: (a) Study of mitochondrial DNA in a patient with MIDD. (b) REVIEW OF THE LITERATURE on the impact of the m.3243A>G mutation on glucose metabolism and on the physiology of the hearing process. SETTINGS: Outpatient diabetes and nutrition department and molecular nutrition laboratory. METHODS: (a) Polymerase chain reaction followed by restriction fragment analysis identified the m.3243A>G mutation. (b) REVIEW OF THE LITERATURE from 1994 to 2009. RESULTS: (a) Molecular study: the m.3243A>G mutation was detected with an appreciable level of heteroplasmy. (b) REVIEW OF THE LITERATURE: the strial marginal cells located near the organ of Corti fulfill two characteristics: they are rich in mitochondria, and their dysfunction may produce neurosensorial deafness by means of a reduction in the potassium ion concentration of the endolymph. CONCLUSIONS: The m.3243A>G mutation not only underlies a dysfunction of the insulin-producing beta cell of the pancreas but also results in a reduction in adenosine triphosphate production of the strial marginal cells of the inner ear, thus diminishing the energy (in the form of potassium ion gradient) needed for the outer hair cells of the organ of Corti to amplify the soundwaves, particularly at high frequencies.

Differences in acute lung response to elastase instillation in two rodent species may determine differences in severity of emphysema development.

Elastase intratracheal instillation induces early emphysema in rodents. However, Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats. We have reported species differences in oxidant/antioxidant balance modulating antiprotease function early after instillation. We now hypothesize that other components of the initial lung response to elastase might also be species-dependent. Sprague-Dawley rats and Syrian Golden hamsters received a single dose of pancreatic elastase (0.55 U/100 g body wt) to study acute lung injury biomarkers. Using serum, lung, and bronchoalveolar lavage fluid (BALF) samples, we evaluated changes in alveolar-capillary permeability, alpha 1-antitrypsin (α(1)-AT) concentration and activity, glutathione content, and proinflammatory cytokines. Rats showed a large increase in alveolar-capillary permeability and few hemorrhagic changes, whereas hamsters exhibited large hemorrhagic changes (P < 0.01) and mild transendothelial passage of proteins. Western blots showed a 30-fold increase in BALF α(1)-AT concentration in rats and only a 7-fold increase in hamsters (P < 0.001), with [α(1)-AT-elastase] complexes only in rats, suggesting differences in antiprotease function. This was confirmed by the α(1)-AT bioassay showing 20-fold increase in α(1)-AT activity in rats and only twofold increase in hamsters (P < 0.001). In rats, results were preceded by a 3-, 60-, and 20-fold increase in IL-6, IL-1ß, and TNF-α respectively (P < 0.001). In hamsters, only IL-1ß and TNF-α showed mild increases. All parameters studied were back to baseline by 4 days. In conclusion, several components of the initial lung response showed species differences. Cytokine release pattern and functional inhibition of α(1)-AT were the most significant components differing among species and could account for differences in susceptibility to elastase.

In silico evaluation of a control system and algorithm for automated insulin infusion in the ICU setting.

BACKGROUND: It is known that tight control of glucose in the Intensive Care Unit reduces morbidity and mortality not only in diabetic patients but also in those non-diabetics who become transiently hyperglycemic. Taking advantage of a recently marketed subcutaneous glucose sensor we designed an Automatic Insulin Infusion System (AIIS) for inpatient treatment, and tested its stability under simulated clinical conditions. METHODS: The system included: reference glucose, glucose sensor, insulin and glucose infusion controllers and emergency infusion logic. We carried out computer simulations using Matlab/Simulink, in both common and worst-case conditions. RESULTS: The system was capable of controlling glucose levels without entering in a phase of catastrophic instability, even under severe simulated challenges. Care was taken to include in all simulations the 5-10 minute delay of the subcutaneous glucose signal when compared to the real-time serum glucose signal, a well-known characteristic of all subcutaneous glucose sensors. CONCLUSIONS: When tested in-Silico, a commercially available subcutaneous glucose sensor allowed the stable functioning of a proportional-derivative Automatic Insulin Infusion System, which was able to maintain glucose within acceptable limits when using a well-established glucose response model simulating a patient. Testing of the system in vivo using animal models is now warranted.

Near-optimal glycemic control in Chilean women with pregestational type-2 diabetes: persistent macrosomia relates to maternal pre-pregnancy overweight.

UNLABELLED: After a 10-year program intending to improve glycemic control in diabetic pregnancies, we evaluated whether factors underlying macrosomia are similar for type-1 and -2 pregestational diabetic women. PATIENTS AND METHODS: Twenty-three pregnancies in type-1 diabetics (PDM1, age 28.3+/-1.1 years) and 51 pregnancies in type-2 diabetics (PDM2, age 32.8+/-0.6 years) were followed and treated with intensified insulin therapy. Several factors potentially influencing macrosomia were evaluated. STATISTICS: chi-square, Fisher's exact, Student's "t" and Mann-Whitney "U" tests, and ROC analysis. RESULTS: In PDM1 and PDM2, respectively, large-for-gestational-age (LGA) frequencies were 26.08% and 37.25% (NS), antepartum HbA1c values were 6.5+/-0.32 and 6.1+/-0.16 (NS), and pre-pregnancy body mass indexes (BMI) were 23.03+/-0.66 and 30.01+/-0.89 (p<0.0001). In PDM1 the main predictor of LGA was an antepartum HbA1c> or =6.8% (p=0.046), whereas in PDM2 pregestational BMI> or =24 the variable associated (p=0.032) with LGA newborns. CONCLUSIONS: PDM1 and PDM2 differ in the underlying factors related to macrosomia. Whereas in PDM1 the antepartum HbA1c emerged as the most significant variable, suggesting that glycemic control largely determines macrosomia, in PDM2 with near-optimal glycemic control, macrosomia related to pregestational BMI.

Differences in lung glutathione metabolism may account for rodent susceptibility in elastase-induced emphysema development.

Syrian Golden hamsters develop more severe emphysema than Sprague-Dawley rats after intratracheal instillation of the same dose of elastase/body weight. Although species variations in antielastase defenses may largely explain these results, other variables, such as differences in lung antioxidants, cannot be overlooked since oxidative stress modulates antiprotease activity. We propose that elastase instillation might affect lung glutathione (GSH) metabolism differently in these species. Our aim was to study in hamsters and rats, lung glutathione metabolism at different times, from the stage of diffuse alveolar damage to advanced emphysema. We measured total and oxidized glutathione content as well as activity and expression of enzymes related to GSH synthesis and redox cycling: gamma-glutamylcysteine synthetase, glutathione peroxidase, and glutathione reductase. Whereas rats showed no significant changes in these measurements, hamsters showed significant derangement in GSH metabolism early after elastase instillation: 25% fall in total GSH (P < 0.05) with no increase in oxidized glutathione associated with reduced enzyme activities 24 h after elastase [60% for gamma-glutamylcysteine synthetase (P < 0.01), 30% for glutathione peroxidase (P < 0.01), and 75% for glutathione reductase (P < 0.001)]. GSH homeostasis was restored at the end of the first week, involving transient increased expression of these enzymes. We conclude that elastase induces significant alterations in GSH metabolism of hamster lungs and no overall change in rat lungs. Although differences in disease severity may account for our findings, the hamster becomes vulnerable to functional inhibition of alpha(1)-antitrypsin by oxidants and thus, even more susceptible to injury than it would be, considering only its low alpha(1)-antitrypsin level.

[Reference values for inspiratory capacity in healthy nonsmokers over age 50 years]. / Valores de referencia de la capacidad inspiratoria en sujetos sanos no fumadores mayores de 50 años.

OBJECTIVE: The role of dynamic hyperinflation in triggering dyspnea and limiting exercise capacity in patients with chronic obstructive pulmonary disease has been recognized in recent years. The degree of dynamic hyperinflation can be assessed by measuring reduction in inspiratory capacity (IC). The aim of this study was to establish reference values for IC in healthy individuals of both sexes between the ages of 50 and 87 years, as such data are scarce in the literature. SUBJECTS AND METHODS: We studied 155 healthy volunteers (93 women) with normal spirometry. None had a prior history of respiratory, cardiovascular, or systemic diseases that might alter lung function. All were never-smokers. IC was measured during a normal, unforced inspiration to total lung capacity starting from functional residual capacity. The highest value of 6 satisfactory maneuvers was recorded. Sex, height, age, and weight were included in the regression equations. One thousand bootstrap samples for each sex were also analyzed. RESULTS: For each sex, we found that a model including age, height, and weight produced IC prediction equations with a coefficient of determination (r2) of 0.414 for women and 0.447 for men. The mean (SD) intrasubject coefficient of variation was 4.3% (2%) for IC measured during a single session and 5.1% (0.4%) for measurements from 5 weekly sessions. CONCLUSIONS: Our results provide reference equations for IC that are valid for a healthy population over 50 years of age. Predicted values were similar to those recently obtained in an Italian population aged between 65 and 85 years.

[Glutathione metabolism during postnatal development of the rat lung]. / Metabolismo del glutatión y desarrollo posnatal del pulmón de la rata.

BACKGROUND: Significant changes in lung antioxidants occur in preparation for birth. Little is known about physiological regulation of antioxidants in the postnatal period. AIM: To study the glutathione system in the lungs during postnatal development. MATERIAL AND METHODS: In the lungs of 7, 15, 21, 50 and 70 days old Sprague-Dawley rats we measured total and oxidized glutathione content as well as the activity of the limiting enzyme in glutathione synthesis (y-GCS) and of the enzymes glutathione peroxidase (GPx) and glutathione reducíase (GRd). RESULTS: Between 7 and 15 days the activities of GPx and GRd increase 32% and 26%, respectively (p <0.001). Whereas GPx activity remains high throughout the rest of the study period, GRd activity decreases progressively reaching adulthood values at 7 days. y-GCS activity shows a gradual increase that reaches significance at 50 days when it doubles values observed at 7 days (p <0.05). A significant correlation was found between GPx and GRd activities over the entire period (r =0.62, p <0.0001). Strength of the correlation is age dependent due to the differences in time course of the enzyme changes. Whereas total GSH does not change, oxidized glutathione decreases from 7% at 7 and 15 days to 4% later on (p <0.01). CONCLUSIONS: The activity of several enzymes involved in glutathione metabolism increases during postnatal development of the rat lung. Interpretation of lung responses to injurious agents needs to be done taking into consideration the physiological regulation of antioxidants during postnatal development.

Rat and hamster species differences in susceptibility to elastase-induced pulmonary emphysema relate to differences in elastase inhibitory capacity.

Syrian Golden hamsters develop severe emphysema after a single intratracheal dose of elastase, whereas Sprague-Dawley rats exhibit mild emphysema with the same dose per kilogram body weight. We hypothesized that the development of severe emphysema is prevented in rats by the high serum level of alpha1-antitrypsin reported in rats, compared with hamsters, which provides for a high lung elastase inhibitory capacity (EIC). To explore this possibility, we challenged the antiprotease system of the rats by treating them with three similar weekly doses of elastase. Four months after treatment, we evaluated changes in histology, volume, and elastic properties of rat lungs and compared them with those of hamsters receiving a single dose of elastase. We also measured serum alpha1-antitrypsin levels and serum and lung EIC in control rats and hamsters. Results showed that, in association with 40% less serum and lung EIC compared with rats (P < 0.001), hamster lungs had upper-lobe bullae formation, severe microscopic emphysema, a fourfold increase in lung volume (P < 0.01) and a threefold increase in constant k, an index of compliance, of the lung deflation pressure-volume curve (P < 0.01). In contrast, rats developed mild emphysema, with only 50% increase in volume (P < 0.05) and 60% increase in constant k (P < 0.01). In conclusion, two species that differ in serum and lung EIC exhibit significant differences in emphysema development after elastase. Rats with high EIC, despite receiving three doses of elastase, showed significantly less derangement of morphological and physiological parameters than hamsters with low EIC receiving a single dose.

Metabolismo del glutatión y desarrollo posnatal del pulmón de la rata / Glutathione metabolism during postnatal development of the rat lung

Background: Significant changes in lung antioxidants occur in preparation for birth. Little is known about physiological regulation of antioxidants in the postnatal period. Aim: To study the glutathione system in the lungs during postnatal development. Material and methods: In the lungs of 7, 15, 21, 50 and 70 days old Sprague-Dawley rats we measured total and oxidized glutathione content as well as the activity of the limiting enzyme in glutathione synthesis (y-GCS) and of the enzymes glutathione peroxidase (GPx) and glutathione reducíase (GRd). Results: Between 7 and 15 days the activities of GPx and GRd increase 32 percent and 26 percent, respectively (p <0.001). Whereas GPx activity remains high throughout the rest of the study period, GRd activity decreases progressively reaching adulthood values at 7 days. y-GCS activity shows a gradual increase that reaches significance at 50 days when it doubles values observed at 7 days (p <0.05). A significant correlation was found between GPx and GRd activities over the entire period (r =0.62, p <0.0001). Strength of the correlation is age dependent due to the differences in time course of the enzyme changes. Whereas total GSH does not change, oxidized glutathione decreases from 7 percent at 7 and 15 days to 4 percent later on (p <0.01). Conclusions: The activity of several enzymes involved in glutathione metabolism increases during postnatal development of the rat lung. Interpretation of lung responses to injurious agents needs to be done taking into consideration the physiological regulation of antioxidants during postnatal development.

[Clinical and functional benefits of adding theophylline to a standard treatment with short acting bronchodilators in patients with COPD]. / Beneficios clínicos y funcionales de agregar teofilina a la terapia inhalatoria con broncodilatadores de acción corta en pacientes con enfermedad pulmonar obstructiva crónica.

BACKGROUND: Although theophylline is considered a third line bronchodilator drug for the treatment of chronic obstructive pulmonary disease (COPD), it is widely used in Chile, because it is administered orally and has a moderate cost. AIM: To evaluate if theophylline adds clinical and/or functional benefits when associated to standard recommended inhaled bronchodilator therapy. SUBJECTS AND METHODS: Thirty-eight stable COPD patients who accepted to participate in the study approved by the Ethics Committee of our institution were studied. Using a randomized double-blind placebo-controlled study, theophylline (250 mg) or placebo was administered twice a day for 15 days in addition to inhaled salbutamol and ipratropium bromide. Prior to and at the end of the study, patients underwent: a) a spirometry to evaluate changes in dynamic pulmonary hyperinflation using slow vital capacity (SVC) and inspiratory capacity (IC), b) the 6 min walking distance (6 MWD); and c) measurement of maximal inspiratory and expiratory pressures. Dyspnea and quality of life (QoL) were evaluated using appropriate questionnaires. RESULTS: Compared to placebo, patients on theophylline showed significant increases in SVC (p=0.014), IC (p=0.002), and 6 MWD (p=0.005). They also experienced an improvement in dyspnea (p=0.042) and QoL (p=0.011). All patients improved at least one of these parameters with 53% of the patients showing an improvement in 3 or more. CONCLUSIONS: Our results indicate that adding theophylline to standard treatment with inhaled bronchodilators provides additional benefits in stable COPD patients by reducing dynamic pulmonary hyperinflation, improving exercise tolerance, dyspnea and QoL.