[Increase in severe acute respiratory infections in children during the last phase of the COVID-19 pandemic]. / Incremento de infecciones respiratorias agudas graves en niños durante la última etapa de la pandemia COVID-19.

OBJECTIVE: The COVID-19 pandemic has caused a variation in the circulation of respiratory pathogens. Our aim was to analyze the epidemiology of severe acute respiratory infections (SARI) in children during 3 years of the COVID-19 pandemic, in comparison with a previous period. METHODS: An observational study was conducted in a tertiary hospital in Spain, which analyzed the frequency and characteristics of patients admitted for SARI in the Pediatric Intensive Care Unit (PICU) during the COVID-19 pandemic (1 March 2020 to 28 February 2023), compared to pre-pandemic period (1 March 2017 to 29 February 2020). RESULTS: A total of 268 patients were included (59.6% males). The median age was 9.6 months (IQR 1.7 - 37). In the pre-pandemic period, there were 126 admissions with an average of 42 admissions/year. During the pandemic, there were 142 admissions, observing a significant reduction in admissions in the first year (12 admissions/year), in contrast to 82 admissions during the third year, which represented an increase of 95% compared to the average of admissions/year in pre-pandemic. In addition, in the last year there was evidence of an increase in viral coinfections in relation to pre-pandemic period (54.9% vs 39.7%; p=0.032). There were no differences in length of hospital stay or PICU stay. CONCLUSIONS: During the last year, coinciding with low rates of hospitalization for COVID in Spain, we observed a notable increase in admissions to the PICU for SARI. Probably, the prolonged period of low exposure to pathogens due to the measures adopted during the pandemic might have caused a decrease in population immunity with a rise in severe respiratory infections.

Morphological criteria to distinguish cell death induced by apoptotic and necrotic treatments.

We present a comparative study of apoptotic and necrotic morphology (light and scanning electron microscopy), induced by well known experimental conditions (photodynamic treatments, etoposide, hydrogen peroxide, freezing-thawing and serum deprivation) on cell cultures. Our results indicate that morphological criteria (apoptotic cell rounding and shrinkage, and appearance of membrane bubbles in early necrosis) allow to distinguish these cell death mechanisms, and also show that, independently of the damaging agents, the necrotic process occurs in a characteristic sequence (coalescence of membrane bubbles in a single big one that detaches from cells remaining on the substrate).

Necrotic cell death induced by photodynamic treatment of human lung adenocarcinoma A-549 cells with palladium(II)-tetraphenylporphycene.

In this study we describe photodamaging and photokilling effects of palladium(II)-tetraphenylporphycene (PdTPPo) (previously incorporated into dipalmitoylphosphatidylcholine liposomes) on the human lung adenocarcinoma A-549 cell line. No dark cytotoxicity was found when the drug was applied at 10(-6) M or 5 x 10(-7) M for 1 or 18 h, respectively. After 1-h treatment with 10(-7) M or 5 x 10(-7) M PdTPPo followed by red light irradiation for variable times, dose-dependent lethal effects were observed in A-549 cells. Apoptosis was not found after the above photodynamic treatments or under even milder sublethal conditions. In contrast to HeLa cells subjected to PdTPPo photosensitization where either apoptosis or necrosis were induced, morphological analysis and electrophoretical DNA pattern of A-549 cells always revealed a clearly necrotic death mechanism. However, A-549 cells died by apoptosis after serum and L-glutamine deprivation, indicating that only the photodynamically induced apoptosis was inhibited. Immunofluorescent labeling revealed that microtubules and actin microfilaments were immediately and strongly damaged by photodynamic treatments with PdTPPo. No metaphase arrest and/or mitotic alterations were observed after phototreatments. Present results show that the cell type plays a fundamental role in relation to the apoptotic or necrotic response to photosensitization, and that cytoskeletal components are important targets implicated in cell death processes.

Photokilling of cultured tumour cells by the porphyrin derivative CF3.

We have analysed the photosensitizing properties of the new porphyrin 5-(4-N-(N-2',6'-dinitro-4'-trifluoromethylphenyl)aminophenyl)-10,15,20-tris(2,4,6-trimethoxyphenyl) porphyrin (CF3) on HeLa cells. The fluorescence and singlet oxygen quantum yield for CF3 were, respectively, phiF = 0.032 and phidelta = 0.25. Cell treatments were done with 5 x 10(-6) M CF3 incorporated into liposome vesicles. Under violet-blue exciting light, the red fluorescence of CF3 was mainly detected in lysosome-like granules. No dark cytotoxicity was observed using high concentration (5 x 10(-6) M) and long incubation time (18 h). Cell cultures treated for 18 h with CF3 and exposed to light (360 < lambda < 460 nm; 8 mW/cm2) for 7 min revealed a great amount of apoptotic (75.8%) and detached cells (62%) 8 h later, leading to a cell lethality of 85% (LD85). Apoptosis was identified by chromatin fragmentation and DNA ladder in gel electrophoresis. Necrotic cells were found using 15 min irradiation (LD96) and showed first small and then giant bubbles at the cell surface, with homogeneous nuclear condensation. Incubation with CF3 for 3 h followed by 7 min irradiation (LD38) produced a mitotic arrest 18 h later (mitotic index: 25.1%). Forty-eight hours after this metaphase blockage, cultures showed a great number of apoptotic cells. Taking into account these results, CF3 could be a valuable photosensitizer for the photodynamic therapy of cancer.