Effects of Streptococcus pneumoniae on the ultrastructure of alveolar epithelial cells type Ⅱ in the lung tissues of mice and children / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To explore the possible mechanisms of lung necrosis by examining the effects of Streptoccus pneumoniae (S.p) on the ultrastructure of alveolar epithelial cells type Ⅱ(AEC-Ⅱ) in the lung tissues of mice and children.</p><p><b>METHODS</b>The suspended solutions of S.p strains cultured from the blood of a child with pneumococcal necrotizing pneumonia (PNP) (0.3 mL, CFU: 1×108/L) were instilled into the trachea of pathogen-free mice to prepare PNP model. The same amount of normal saline was given for the control group (10 mice). The samples (1 mm3) from the lower lobe of right lung of the mice were obtained 92 hrs later and fixed in 2.5% glutaraldehyde. Normal and abnormal lung tissues (1 mm3) were obtained while operation for the left lower lobe pulmonary cavity excision in the child with PNP. The specimens were fixed in 2.5% glutaraldehyde and stored at 4℃. A transmission electron microscope was employed for the examination of the ultrastructure of AEC-Ⅱ in the lung tissues.</p><p><b>RESULTS</b>Quantitative reduction and exfoliation of microvilli in S.p-infected AEC-Ⅱ were observed in both mice and this child compared with the control. Enlarged size, enhanced evacuation and reduced density of the lamellar bodies were also presented. The number of mitochondria was obviously reduced. The nucleolus chromatin concentrated and showed an inhomogeneous distribution.</p><p><b>CONCLUSIONS</b>S.p infection results in comparable damage to the ultrastructure of AEC-Ⅱ in mice and children that may represent one of the primary causes responsible for S.p-induced lung tissue necrosis.</p>

Early clinical presentations and MRI characteristics in newborns with cerebral infarction / 中国当代儿科杂志

<p><b>OBJECTIVE</b>The present study aimed to characterize the clinical presentations and magnetic resonance imaging including conventional MRI and diffusion-weighted imaging (DWI) in newborns with cerebral infarction.</p><p><b>METHODS</b>Clinical records of 16 newborn infants with cerebral infarction were reviewed. All cases underwent DWI examination in addition to conventional MRI examination [T1-weighted (T1W) and T2-weighted (T2W)]within 5 days after birth. Five patients received the second MRI examination at the age of 11 to 18 days.</p><p><b>RESULTS</b>Eight patients had antenatal risk factors, 9 had intranatal risk factors, and no postnatal risk factors were found. Seizures as the first symptom were noted in 11 neonates, with a short duration and a low frequency. The first imaging examination (within 5 days) showed a slight hypointensity on T1W, a slight hyperintensity on T2W and significantly increased signal intensity with a clear boundary on DWI in the lesions. In the MRI re-examination, more obvious hypointensity on T1W and hyperintensity on T2W were noted, while hypointensity was shown on DWI in the lesions compared with the first imaging results.</p><p><b>CONCLUSIONS</b>Seizures characterized by short duration and low frequency usually may be the first symptom in newborns with cerebral infarction. A hyperintensity on DWI was shown in the lesions at the early stage of neonatal cerebral infarction. A hypointensity on T1W and a hyperintensity on T2W were demonstrated in the lesions with increasing disease duration.</p>