Protective effects of poly(lactic-co-glycolic acid) nanoparticles loaded with erythropoietin stabilized by sodium cholate against glutamate-induced neurotoxicity.

The final aim of this study was to confirm the neuroprotective effects of recombinant human erythropoietin (rhEPO)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles stabilized by sodium cholate (rhEPO-Ch-NP) and compare their effects with those of rhEPO using an in vitro model of cerebral ischemia. Glutamate-induced excitotoxic damage on SH-SY5Y cells, a human neuroblastoma cell line, with or without rhEPO-Ch-NPs was quantitatively evaluated. The rhEPO-Ch-NPs were carefully prepared using a water-in-oil-in-water (w/o/w) emulsion solvent evaporation technique with PLGA, sodium cholate hydrate, and ethyl acetate. The rhEPO-Ch-NPs were fully characterized by both transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). In addition, significant intracellular uptake of these particles was monitored by confocal microscopy. Notably, the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and nuclear changes observed by 4',6-diamidino-2-phenylindole (DAPI) staining in SH-SY5Y cells demonstrated that rhEPO-Ch-NPs were safer at any concentration investigated and rescued more neuronal cells, while preserving normocytic features against glutamate-induced excitotoxic damages compared to rhEPO.

Neuroprotective effect of estradiol-loaded poly(lactic-co-glycolic acid) nanoparticles on glutamate-induced excitotoxic neuronal death.

Different concentrations of estradiol (E2)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (E2-PLGA-NPs) were synthesized using the emulsion-diffusion method. Transmission electron microscopy results showed that the average particle size of E2-PLGA-NPs was 98 ± 1.9 nm when stabilized with polyvinyl alcohol and 103 ± 4.9 nm when stabilized with Tween-80. Fourier transform-infrared spectroscopy with diamond attenuated total reflectance was used to identify the presence or absence of E2 molecules in PLGA nanocapsules. Cell proliferation was assessed after treating SH-SY5Y neuroblastoma cells with 1 nM-1 µM of E2 and E2-PLGA-NPs. The neuroprotective efficacy against glutamate-induced excitotoxicity was also investigated in SH-SY5Y neuroblastoma cells. Neuroprotection was greater in E2-PLGA-NP-treated cells than in cells treated with the same concentration of E2. Furthermore, E2- and E2-PLGA-NP-treated cells expressed more p-ERK1/2 and p-CREB than cells treated with glutamate only. Moreover, the expression of p-ERK1/2 was higher than that of p-CREB. In this study, p-ERK1/2 had a greater influence on the neuroprotective effect of E2 and E2-PLGA-NPs than p-CREB.

Repeated derecruitments accentuate lung injury during mechanical ventilation.

OBJECTIVES: The aim of our study was to assess whether repeated derecruitments induced by the repetitive withdrawal of high positive end-expiratory pressure could induce lung injury in a swine model. DESIGN: Prospective, randomized, experimental animal study. SETTING: University laboratory. SUBJECTS: Specific pathogen-free pigs (Choong-Ang Laboratory Animals, Seoul, Korea) weighing around 30 kg. INTERVENTIONS: After lung injury was induced by repeated saline lavage, pigs were ventilated in pressure-limited mode with the highest possible positive end-expiratory pressure with a tidal volume of 8 mL/kg and maximum inspiratory pressure of 30 cm H2O. With this initial ventilator setting, the control group (n = 5) received ventilation without derecruitments for 4 hours, and in the derecruitment group (n = 5), derecruitments were repeatedly induced by intentional disconnection of the ventilatory circuit for 30 seconds every 5 minutes for 4 hours. MEASUREMENTS AND MAIN RESULTS: After the initial increase in positive end-expiratory pressure, the PaO2 increased to greater than 450 mm Hg in both groups. The PaO2 remained at greater than 450 mm Hg in the control group persistently, but in the derecruitment group, PaO2 significantly decreased to 427.7 mm Hg (adjusted p = 0.03) after 2 hours and remained significant for the rest of the study. PaCO2, oxygenation index, and alveolar-arterial oxygen gradient also significantly increased after 2 hours compared with the control group. However, the variables of respiratory mechanics except for minute volume at 2-hour point showed no difference between the two groups for the duration of the study. Histologically, significant bronchiolar injury was observed in the dependent portion of the derecruitment group compared with the controls (p = 0.03), but not in the nondependent area of the lung. CONCLUSIONS: Repeated derecruitments exacerbated lung injury, particularly at the bronchiolar level in the dependent portion. Strategies to minimize this type of injury should be incorporated when designing optimal ventilator strategies in acute respiratory distress syndrome patients.

[Usefulness of multichannel intraluminal impedance-pH metry in children with suspected gastroesophageal reflux disease].

BACKGROUND/AIMS: pH monitoring of the esophagus has been considered as the gold standard for the measurement of acid reflux. However, it has several limitations related to its inability to detect nonacid reflux. We conducted this study to characterize the proportion of acid and non-acid reflux events in children using pH-multichannel intraluminal impedance (MII) monitoring and to determine the correlation of the symptom index with non-acid and acid reflux events. METHODS: Seventy-five children, aged from 9 days to 12 years, underwent 24 hour pH-MII monitoring at Asan Medical Center from March 2006 to June 2007. We investigated the underlying disease and main problems related to gastroesophageal reflux (GER) of the patients, the number of acid and nonacid reflux, symptom index, symptom sensitivity index in pH monitoring only and pH-MII monitoring. RESULTS: While 2,247 reflux events were detected by MII, and only 967 reflux events were detected by pH probe alone. The percentage of acid reflux was 43% (967) and that of non-acid was 57% (1,280). The non-acid reflux increased at postprandial time (p<0.001). The symptom index increased when measured by pH-MII (31.1%) compared with those by pH probe alone (8.2%) (p=0.003). CONCLUSIONS: This study suggests that significant number of GER include non-acid reflux which cannot be detected by pH probe alone, therefore combining pH with MII monitoring is a valuable diagnostic tool for diagnosing GER in children.

Polymorphisms of interferon-gamma and interferon-gamma receptor 1 genes and pulmonary tuberculosis in Koreans.

BACKGROUND AND OBJECTIVE: Many genetic variations are thought to be risk factors for the development of pulmonary tuberculosis (TB). The association of interferon-gamma (IFN-gamma) and IFN-gamma receptor 1 (IFN-gammaR1) gene polymorphisms with pulmonary TB is controversial. This study examined the association between IFN-gamma and IFN-gammaR1 gene polymorphisms and pulmonary TB among Koreans. METHODS: Eighty patients with culture-confirmed pulmonary TB and 80 controls were studied. Polymorphisms of the IFN-gamma gene at position +874 were determined using the amplification refractory mutation system PCR assay, and the IFN-gammaR1 gene was genotyped at positions -611, -270, -56 and +95 employing matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using genomic DNA. RESULTS: The genotype and allele frequencies of the IFN-gamma and IFN-gammaR1 gene polymorphisms did not differ significantly between the patients with pulmonary TB and controls. CONCLUSIONS: The IFN-gamma and IFN-gammaR1 gene polymorphisms do not appear to be responsible for host susceptibility to pulmonary TB in the Korean population.

Decreased cytokine production in patients with nontuberculous mycobacterial lung disease.

Nontuberculous mycobacteria (NTM) are intracellular pathogens that elicit a specific T-cell response characterized by the production of proinflammatory cytokines, including interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-12. However, little information exists regarding the levels of specific cytokines in patients with NTM lung disease. Therefore, we compared cytokine production in peripheral blood mononuclear cells (PBMCs) from patients with NTM lung disease with that in PBMCs from healthy controls. Pro- and anti-inflammatory cytokine production was measured by enzyme-linked immunosorbent assay in the PBMCs of 29 patients with NTM lung disease and 15 healthy controls. Phytohemagglutinin (PHA)-induced IFN-gamma production and lipopolysaccharide (LPS)-induced production of TNF-alpha and IL-12p40 were significantly lower in the PBMCs of patients with NTM lung disease than in those of the healthy controls. The production of these cytokines did not differ significantly between patients infected with Mycobacterium avium complex (MAC) and those infected with Mycobacterium abscessus; however, IL-10 production was lower in patients infected with M. abscessus than in those infected with MAC. Decreased IFN-gamma, TNF-alpha, and IL-12 production may be associated with host susceptibility to the development of MAC and M. abscessus lung disease.

Polymorphisms of interferon-gamma and interferon-gamma receptor 1 genes and non-tuberculous mycobacterial lung diseases.

Interferon-gamma (IFN-gamma) is crucial for host defense against mycobacterial infections. Recent studies have indicated that IFN-gamma and IFN-gamma receptor 1 (IFN-gammaR1) gene polymorphisms are associated with susceptibility to pulmonary tuberculosis. The aim of this study was to test the hypothesis that IFN-gamma and IFN-gammaR1 gene polymorphisms influence susceptibility to lung disease caused by non-tuberculous mycobacteria (NTM). Seventy-six patients with the nodular bronchiectatic form of NTM lung disease (37 patients with Mycobacterium avium complex infection and 39 patients with Mycobacterium abscessus infection) and 80 controls were included. Polymorphisms of the IFN-gamma gene at position +874 were determined by the amplification refractory mutation system (ARMS) polymerase chain reaction assay and IFN-gammaR1 gene at positions -611, -270, -56 and +95 was genotyped by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry using genomic DNA. IFN-gammaR1 -270 and +95 polymorphisms were not present in any of the patients or controls. The patients with NTM lung disease showed no significant difference from controls in genotype and allele frequencies of the IFN-gamma +874 and IFN-gammaR1 -611 and -56 polymorphisms. The IFN-gamma +874 and IFN-gammaR1 -611 and -56 polymorphisms do not appear to be responsible for host susceptibility to NTM lung disease, at least in the Korean population.

A Peptide with anti-transglutaminase activity decreases lipopolysaccharide-induced lung inflammation in mice.

Octapeptide R2 (KVLDGQDP), which has anti-transglutaminas (TGase) activity, decreases inflammation in allergic conjunctivitis model in guinea pigs. The authors examined the effect of R2 on lipopolysaccharide (LPS)-induced lung injury in BALB/c mice. R2 inhalation significantly decreased neutrophil count and cytokine mRNA expression in the lungs of LPS (25 mg/kg)-treated mice (P < .05). It also showed a tendency for decreased tumor necrosis factor (TNF)-alpha-immunoreactive protein in lung homogenates and significantly decreased TNF-alpha-immunoreactive protein in the serum of LPS-injected mice (P < .05). These results indicate that TGase may be a new therapeutic target in LPS-induced lung inflammation.

Recruitment maneuvers attenuate repeated derecruitment-associated lung injury.

OBJECTIVE: Repeated derecruitments of previously recruited lungs can exacerbate lung injuries during mechanical ventilation. The aim of this study was to assess lung injury associated with repeated derecruitments and to assess whether this type of injury could be attenuated by recruitment maneuvers. DESIGN: Prospective, randomized, experimental animal study. SETTING: University laboratory. SUBJECTS: New Zealand White rabbits. INTERVENTIONS: Twenty-one rabbits were ventilated in pressure-controlled mode with constant tidal volume (10 mL/kg). After lung injury was induced by repeated saline lavage, positive end-expiratory pressure (PEEP) at a lower inflection point was applied for 3 hrs. The control group (n = 7) received ventilation with the same PEEP for 3 hrs without derecruitments. In the derecruitment group (n = 7), derecruitment was repeatedly induced by intentional disconnection of the ventilatory circuit for 1 min every 10 mins for 3 hrs. In the recruitment maneuver group (n = 7), continuous positive airway pressure of 30 cm H2O was applied for 30 secs after each derecruitment. MEASUREMENTS AND MAIN RESULTS: After PEEP levels were increased to lower the inflection point value, Pao2 increased to >500 mm Hg in all groups. Increased Pao2 persisted at >450 mm Hg in the control and recruitment maneuver groups, whereas progressive declines in arterial oxygen levels were observed in the derecruitment group (median, 381.1 mm Hg [interquartile range, 350.1-466.7 mm Hg] at 2 hrs and 318.2 mm Hg [214.3-414.9 mm Hg] at 3 hrs, p < .05 compared with other groups). Histologically, there was significantly increased hyaline membrane formation in alveolar ducts in the derecruitment group compared with the control group (p = .005). Also, significantly more membranous and respiratory bronchiolar injuries were observed in the derecruitment group compared with the control and recruitment maneuver group (p < .005). CONCLUSIONS: These findings suggest that repeated derecruitments could induce lung injuries during mechanical ventilation, and recruitment maneuvers may attenuate derecruitment-associated lung injuries.