Lighting-Up the Far-Red Fluorescence of RNA-Selective Dyes by Switching from Ortho to Para Position.

Fluorescence imaging is constantly searching for new far-red emitting probes whose turn-on response is selective upon the interaction with specific biological targets. Cationic push-pull dyes could indeed respond to these requirements due to their intramolecular charge transfer (ICT) character, by which their optical properties can be tuned, and their ability to interact strongly with nucleic acids. Starting from the intriguing results recently achieved with some push-pull dimethylamino-phenyl dyes, two isomers obtained by switching the cationic electron acceptor head (either a methylpyridinium or a methylquinolinium) from the ortho to the para position have been scrutinized for their ICT dynamics, their affinity towards DNA and RNA, and in vitro behavior. By exploiting the marked fluorescence enhancement observed upon complexation with polynucleotides, fluorimetric titrations were employed to evaluate the dyes' ability as efficient DNA/RNA binders. The studied compounds exhibited in vitro RNA-selectivity by localizing in the RNA-rich nucleoli and within the mitochondria, as demonstrated by fluorescence microscopy. The para-quinolinium derivative showed some modest antiproliferative effect on two tumor cell lines as well as improved properties as an RNA-selective far-red probe in terms of both turn-on response (100-fold fluorescence enhancement) and localized staining ability, attracting interest as a potential theranostic agent.

Room-Temperature Phosphorescence and Cellular Phototoxicity Activated by Triplet Dynamics in Aggregates of Push-Pull Phenothiazine-Based Isomers.

In this study, we report a comprehensive time-resolved spectroscopic investigation of the excited-state deactivation mechanism in three push-pull isomers characterized by a phenothiazine electron donor, a benzothiazole electron acceptor, and a phenyl π-bridge where the connection is realized at the relative ortho, meta, and para positions. Spin-orbit charge-transfer-induced intersystem crossing takes place with high yield in these all-organic donor-acceptor compounds, leading also to efficient production of singlet oxygen. Our spectroscopic results give clear evidence of room-temperature phosphorescence not only in solid-state host-guest matrices but also in highly biocompatible aggregates of these isomers produced in water dispersions, as rarely reported in the literature. Moreover, aggregates of the isomers could be internalized by lung cancer and melanoma cells and display bright luminescence without any dark cytotoxic effect. On the other hand, the isomers showed significant cellular phototoxicity against the tumor cells due to light-induced reactive oxygen species generation. Our findings strongly suggest that nanoaggregates of the investigated isomers are promising candidates for imaging-guided photodynamic therapy.

Lung Ultrasound for the Differential Diagnosis of Respiratory Distress in Neonates.

BACKGROUND: Respiratory distress (RD) is the most common neonatal illness. Lung ultrasound (LUS) is a technique previously tested in neonatal studies on RD, but literature regarding its routine clinical applicability is still lacking. OBJECTIVE: To assess the concordance between LUS performed by neonatologists with different training levels and chest X-ray (CXR) for the diagnosis of RD in newborns during the first 24 h of life. METHODS: We enrolled newborns with RD during the first 24 h of life. Patients underwent LUS and CXR. LUS and CXR diagnosis were compared to evaluate concordance. Twenty percent of patients received two LUS (one from an experienced and one from a novice sonographer) to calculate the interobserver agreement. The difference in time needed to reach a diagnosis with LUS and CXR, and from novice and expert operators, was measured. RESULTS: We studied 124 patients; 134 diagnoses were reported. The concordance between LUS and CXR diagnosis was 91% (95% CI 86-96%) with a κ statistic of 0.88 (95% CI 0.81-0.94). The median time to diagnosis was shorter for LUS (9.5 min, IQR 5-15) than for CXR (50 min, IQR 33-64) (p < 0.0001). In 25/124 patients, LUS was performed by both novice and experienced sonographers with complete concordance. The median time to diagnosis was shorter for expert (9 min, IQR 5-15) than novice operators (15 min, IQR 10-20) (p < 0.0002). CONCLUSION: LUS and CXR have a high concordance in the differential diagnosis of neonatal RD in the first 24 h of life. LUS has a shorter operation time than CXR.

Change of Cerebral Oxygenation during Surfactant Treatment in Preterm Infants: "LISA" versus "InSurE" Procedures.

Objectives The aim of the study was to compare the effects on cerebral oxygenation in preterm infants of two different procedures for surfactant administration: the LISA (low-invasive method of surfactant administration) and the InSurE (Intubation, SURfactant administration, Extubation). Study Design Twenty premature infants with respiratory distress syndrome were assigned to receive surfactant either by "LISA" (n = 10) or "InSurE" (n = 10) procedure. Patients were continuously studied by near-infrared spectroscopy (NIRS) for the measurement of cerebral regional oxygenation (rSO2C) and calculation of cerebral fractional oxygen extraction rate (cFTOE), and NIRS data were recorded 30 minutes before (T0) surfactant administration, during the procedure (Tproc), and 30 (T1), 60 (T2T2), and 120 minutes (T3) afterward. Cerebral blood flow velocity (CBFV) was studied in the anterior cerebral artery at T0, T1, and T3. Results SpO2 significantly decreased at Tproc in comparison with T0, T1, T2, and T3 and the decrease was higher in the LISA than in the InSurE group. rSO2C was lower at tproc and T3 in the LISA than in the InSurE group. cFTOE was higher at tproc, t2, and t3 in the LISA group than in the InSurE group. CBFV did not change during the study periods in both groups. Conclusions The LISA and InSurE procedures transiently decreased rSO2C in our population, and the decrease was higher in the LISA group. Consistently, there was a contemporary increase in cFTOE that was higher in the LISA than in the InSurE group, suggesting that it represents a compensatory mechanism.

Peroxisome proliferator-activated receptor-γ agonist pioglitazone reduces the development of necrotizing enterocolitis in a neonatal preterm rat model.

BACKGROUND: Factors affecting innate immunity and acting as inflammatory regulators, such as the nuclear peroxisome proliferator-activated receptors (PPAR) could be crucial in the pathogenesis of necrotizing enterocolitis (NEC). We hypothesized that the PPARγ agonist pioglitazone (PIO) might be effective in preventing the development of NEC and/or reducing its severity. METHODS: We studied preterm rats in which NEC was induced using the hypoxia-hypothermia model. The treatment group (TG; n = 30) received enteral PIO (10 mg/kg/d) for 72 h and the control group (CG; n = 30) did not. Animals were sacrificed 96 h after birth. NEC was diagnosed evaluating histological ileum changes, and mRNA levels of IL-4, IL-12, IL-6, IL-10, INF-γ, and TNF-α cytokines were measured. RESULTS: NEC occurrence was higher in the CG (18/30; 60%) than in the TG (5/30; 16.7%) and was more severe. Proinflammatory IL-12 and INF-γ mRNA levels were significantly lower in the TG than in the CG; conversely, the anti-inflammatory IL-4 mRNA level was significantly higher in the TG than in the CG. CONCLUSION: Our results demonstrate for the first time that PIO is effective in reducing the incidence and severity of NEC and in decreasing renal injuries in a preterm rat model.

Presepsin for the detection of late-onset sepsis in preterm newborns.

BACKGROUND: Late-onset sepsis (LOS) is among the leading causes of morbidity and mortality in preterm newborns, and currently available diagnostic tools are inadequate. The objective of this study was to evaluate the accuracy of presepsin (P-SEP) as novel biomarker of bacterial infection for the diagnosis of LOS in preterm newborns. METHODS: We prospectively studied newborns ≤32 weeks' gestational age with LOS (n = 19) and noninfected controls (n = 21) at 4 to 60 days' postnatal age. At enrollment, and 1, 3, and 5 days later, we ascertained the C-reactive protein, procalcitonin, and P-SEP in the LOS group, whereas P-SEP alone was ascertained in the control group. RESULTS: P-SEP at enrollment was higher in the LOS than the control group (median 1295 vs 562 ng/L, P = .00001) and remained higher throughout the study period. In the LOS group, P-SEP had a borderline reduction at day 1 versus values at enrollment (median 1011 vs 1295 ng/L, P = .05), whereas C-reactive protein and procalcitonin at day 1 did not differ from baseline values. The receiver operating characteristic curve of P-SEP at enrollment shows an area under the curve of 0.972. The best calculated cutoff value was 885 ng/L, with 94% sensitivity and 100% specificity. Negative likelihood ratio was 0.05, and positive likelihood ratio was infinity. CONCLUSIONS: We demonstrated for the first time in a cohort of preterm newborns that P-SEP is an accurate biomarker for the diagnosis of possible LOS and may also provide useful information for monitoring the response to therapeutic interventions.

Splanchnic Tissue Oxygenation for Predicting Feeding Tolerance in Preterm Infants.

BACKGROUND: Feeding intolerance is very frequent in preterm infants, and the development of an early effective biomarker for its prediction could be useful for carrying out a proper feeding strategy. Our aim was to evaluate if the measurement of splanchnic regional oxygenation (rSO2S) and splanchnic fractional oxygen extraction ratio (FOES) using near-infrared spectroscopy (NIRS) is correlated with the time needed to achieve full enteral feeding and if it can predict the development of feeding intolerance. MATERIALS AND METHODS: We measured rSO2S and FOES in preterm infants 25 ± 0 to 31 ± 6 weeks of gestational age at 24-72 hours of life during continuous enteral feeding. RESULTS: Linear regression analysis did not evidence any relationship between rSO2S and FOES and the time for achievement of full enteral feeding. Multivariate logistic regression analysis showed that birth weight <1000 g (relative risk [RR], 4.5; 95% confidence interval [CI], 1.23-16.45) and patent ductus arteriosus occurrence (RR, 9.3; 95% CI, 1.31-66.06) increased the risk of developing feeding intolerance in our population. CONCLUSION: Splanchnic oxygenation and oxygen extraction measured in the first days of life are not correlated with the time needed to achieve full enteral feeding in preterm infants receiving continuous enteral nutrition.