The present study aimed to investigate whether co-administration of mesenchymal stromal cells (MSC) and linezolid (LZD) into a rabbit model of methicillin-resistant Staphylococcus aureus (MRSA)-infected pneumonia would bring a synergistic therapeutic effect. Human umbilical cord-derived MSCs (hUMSCs) were isolated and characterized. A rabbit model of pneumonia was constructed by delivering 1 × 1010 CFU MRSA via a bronchoscope into the basal segment of lower lobe of right lung. Through analyzing vital sign, pulmonary auscultation, SpO2, chest imaging, bronchoscopic manifestations, pathology, neutrophil percentage, and inflammatory factors, we verified that a rabbit model of MRSA-induced pneumonia was successfully constructed. Individual treatment with LZD (50 mg/kg for two times/day) resulted in improvement of body weight, chest imaging, bronchoscopic manifestations, histological parameters, and IL-10 concentration in plasma (P<0.01), decreasing pulmonary auscultation, and reduction of IL-8, IL-6, CRP, and TNF-α concentrations in plasma (P<0.01) compared with the pneumonia model group at 48 and 168 h. Compared with LZD group, co-administration of hUMSCs (1 × 106/kg for two times at 6 and 72 h after MRSA instillation) and LZD further increased the body weight (P<0.05). The changes we observed from chest imaging, bronchoscopic manifestations and pathology revealed that co-administration of hUMSCs and LZD reduced lung inflammation more significantly than that of LZD group. The plasma levels of IL-8, IL-6, CRP, and TNF-α in combined group decreased dramatically compared with the LZD group (P<0.05). In conclusion, hUMSCs administration significantly improved therapeutic effects of LZD on pneumonia resulted from MRSA infection in a rabbit model.

A widened subarachnoid space might be pathologic, potentially pathologic, or simply a normal developmental variant. However, the definition of a normal subarachnoid space width in infants remains unclear, especially on computed tomography (CT) images. To determine the physiological subarachnoid space width among infants aged 1-24 months, its upper limit, and changes with age, we measured the cerebrospinal fluid width on 538 CT images. Measurements were obtained at fixed planes and fixed positions to prevent variance and increase comparability between patients. We observed an asymmetry in the cerebrospinal fluid width of the temporal region. The width increased in all positions until 4-6 months of age, after which it began to decrease, reaching a relatively stable range in infants aged 13-24 months. We suggest considering the 95th percentile of the cerebrospinal fluid width as the upper limit. The correlation between age and the subarachnoid space width should be considered during clinical diagnosing.

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