[Clinical features of parenteral nutrition associated cholestasis in preterm infants].

OBJECTIVE: To analyze the clinical features and influential factors of parenteral nutrition associated cholestasis (PNAC) in preterm infants. METHOD: A total of 159 infants with birth weight less than 2000 grams and/or gestational age less than 34 weeks were exposed to parenteral nutrition for longer than 14 days in NICU during the period from July 2007 to June 2009. Of these infants, 40 cases who had PNAC were aligned into the PNAC group, and the other 119 cases without PNAC were aligned into the non-PNAC group. PNAC occurring time, duration, the degree of PNAC and hepatic injury were observed. Logistic regression analysis was performed to evaluate the correlative factors of PNAC. RESULT: PNAC occurred about (3.3 ± 1.6) weeks after beginning PN, usually lasted for (13.3 ± 5.4) weeks. The maximum direct bilirubin was (135.2 ± 65.5) µmol/L. Of the PNAC patients, 73.7% suffered from hepatic injury. Hepatic injury usually occurred (6.6 ± 3.0) weeks after beginning PN, and lasted for (9.5 ± 5.4) weeks. The highest alanine aminotransferase (ALT) was (121.5 ± 48.4) U/L. The logistic regression of the possible correlative factors showed that time to start enteric feeding, persistence time of PN, asphyxia, small for gestational age, intracranial hemorrhage, were related to PNAC. CONCLUSION: The prognosis of PNAC was good. Early enteral feeding, shorter time of PN, avoidance of the complications such as asphyxia and sepsis, were the important measures to lower PNAC.

[Percutaneous balloon pulmonary valvuloplasty for critical pulmonary stenosis in infants under 6 months of age and short and medium term follow-up].

OBJECTIVE: To evaluate the effect and results of short and medium periods of follow-up of percutaneous balloon pulmonary valvuloplasty for critical pulmonary stenosis of neonates and infants under 6 months of age. METHODS: Between January 2002 and December 2008, 34 consecutive patients aged from 13 to 175 days with critical pulmonary valvular stenosis underwent percutaneous balloon valvuloplasty. Patients records, catheterization data, angiograms and echocardiograms were reviewed. Patients were followed up for 6 months to 4 years (mean 25.5 months) by means of clinical examination and Doppler echocardiography. RESULTS: The pulmonary valvuloplasty was accomplished in 32 (94%) of 34 attempts. Immediately after dilation, right ventricular systolic pressure (RVSP) decreased from (96 ± 28) mm Hg (1 mm Hg = 0.133 kPa) (49 ± 20) mm Hg (P < 0.01), the transvalvular peak to peak systolic gradient (ΔP) decreased from (89 ± 25) mm Hg to (25 ± 12) mm Hg (P < 0.01), and the right ventricular/aortic systolic pressure ratio decreased from 1.2 ± 0.5 to 0.7 ± 0.3 (P < 0.01). One patient died because of cardiac tamponade following rupture of the pulmonary valve annulus, 2 patients developed pericardial effusion, 3 patients had infundibular spasm, 3 patients had a pre-dilation by small balloon and 1 patient had weakened femoral artery pollex. After a follow up period of 6 months to 4 years 3 of 31 patients lost to follow-up. Repeat valvuloplasty was performed in 5 patients (3 neonates), no patient required surgery, and the other 23 patients did not undergo further intervention, a mean peak systolic Doppler gradient of (20 ± 13) mm Hg was found and no significant pulmonary regurgitation was seen. CONCLUSIONS: Percutaneous balloon pulmonary valvuloplasty was effective and safe for the treatment of critical pulmonary stenosis of neonates and infants under 6 months of age with good short and medium term results.

[Maple syrup urine disease of neonates: report of two cases and review of literature].

OBJECTIVE: To analyze and summarize clinical manifestation of maple syrup urine disease (MSUD) of neonates. METHODS: Data of two cases with neonatal MSUD and the reports of 15 cases seen in the past 15 years in China were reviewed and analyzed. RESULTS: There was an increasing number of reports of cases with neonatal MSUD. All the 17 cases had the symptom of poor feeding between 3 h and 8 d after birth; 7 cases had family history; 14 cases showed progressive neurologic signs. Odor of maple syrup occurred in 8 cases. Blood levels of branched-chain amino acids (BCAA) significantly increased in 13 cases and 6 neonates were diagnosed using tandem mass spectrometry. Urinary levels of BCAA and metabolite elevated in 12 cases and 5 neonates were diagnosed using gas chromatography-mass spectrometry. MRI/CT demonstrated abnormal signal in 10 cases. Twelve cases died or their parents gave up treatment and one case had cerebral palsy; 4 cases were treated with BCAA-free formula milk and showed improved outcome. CONCLUSION: Newborns with MSUD often had early appeared non-specific symptoms with poor feeding and lethargy, most cases later showed an odor resembling maple syrup and neurologic signs. For patients who were suspected of having MSUD, blood and urine concentrations of BCAA should be tested for early diagnosis. Specific MRI edema signal from brain suggests the possibility of MSUD. Early intervention and treatment after diagnosis, with compliance of parents, would improve the patient's outcome.

[Establishment and clinical application of a new real time PCR assay for simultaneous detection of human herpesvirus-6A and human herpesvirus-6B].

OBJECTIVE: Human herpesvirus 6 (HHV-6) isolates are classified into two variants, HHV-6A and HHV-6B, based on distinct genetic, antigenic and biological characteristics. HHV-6 has been associated with encephalitis in children recently. This study aimed to establish a real time PCR assay for simultaneous detection of the two subtypes of HHV-6, and apply this new assay to children with suspected encephalitis, then analyze the relationship between the infection with HHV-6 and encephalitis in children. METHOD: The universal primers and variant-specific TaqMan probes were designed based on the highly conserved sequences of the DNA polymerase gene (U38) of HHV-6. The 5' end of the probes for HHV-6A and HHV-6B was labeled with the fluorescein reporter tetrachloro-6-carboxyfluorescein and 6-carboxyfluorescein (6-FAM), separately, while the 3' end were quenched with 6-carboxy-tetramethylrhodamine. The real time PCR assay for simultaneous detection of HHV-6A and HHV-6B was established. Then, the plasmids of HHV-6A and -6B which were diluted by a 10-fold series from 10(9) to 10(0) copies/microl, together with controls were used for testing both sensitivity and specificity of the real time PCR assay. The cerebrospinal fluid (CSF) specimens from 445 cases of suspected encephalitis were tested with this real time PCR and positive samples were then sequenced. RESULT: Both HHV-6A (strain ZJ-159) and HHV-6B (strain GS) were positive on the real time PCR assay. There were no cross-reaction with herpes simplex virus type 1, type 2 (HSV-1, HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), hepatitis B virus, Staphylococcus aureus, Mycoplasma pneumoniae and human DNA. A linear regression curve was obtained when plotting Ct values against the log10 of the viral DNA input for both subtypes of HHV-6. The sensitivity threshold was 10 copies/microl for the real time PCR. HHV-6 positive rate by the real time PCR assay was 4.72% (21/445), including 4 cases with HHV-6A infection, 16 cases of HHV-6B infection and 1 case with mixed HHV-6A and HHV-6B infection. The new PCR assay usually took 2 to 3 hours to provide results. CONCLUSION: This new real time PCR assay can simultaneously detect both subtypes of HHV-6, and have high specificity and sensitivity. It will provide an early and sensitive diagnosis of HHV-6 encephalitis in children.

[Retrospective analysis of elective caesarean section and respiratory distress syndrome in the term neonates].

OBJECTIVE: Severe respiratory distress syndrome (RDS) caused by pulmonary surfactant (PS) deficiency is described not only in preterm infants but also in term babies delivered via caesarean section, especially before the onset of labour (elective caesarean section). Once RDS of term neonates happened, mechanical ventilation is needed, and the infants were at high risk of developing further complications such as persistent pulmonary hypertension of neonates (PPHN), pulmonary air leak and cardiovascular instability, even fatal outcome cannot be avoided. The present study aimed to analyze the association between the elective caesarean section and respiratory distress syndrome (RDS) in term neonates, and to determine the related factors and outcomes of RDS cases in neonatal intensive care unit (NICU) and neonatology ward. METHODS: A retrospective study was conducted at the NICU and the Neonatology Ward of A center (Children's Hospital of Zhejiang University) and the NICU of center B (Obstetrics and Gynecology Hospital of Zhejiang University) on 90 term infants who were diagnosed as RDS between June 2006 and June 2008. The general clinical data, mode of delivery, severity of the radiological sign, pulmonary surfactant (PS) application, the onset time and duration of mechanical ventilation, the ratio of PaO(2) to FIO(2) before mechanical ventilation, oxygenation index (OI), duration of oxygen supplementation, the length of hospital stay and complications including pulmonary air leaks (pneumothorax, pulmonary interstitial emphysema), PPHN, systemic hypotension and ventilator-associated pneumonia (VAP) were collected. The gestational age distribution was studied in RDS cases delivered by elective caesarean section, and the comparative analysis and non-conditional logistic regression analysis wer performed for clinical characteristics and risk factors between the RDS cases with or without complications. P < 0.05 was considered to be significant. RESULTS: There were 88 episodes of elective caesarean section in 90 RDS patients. The proportion of elective caesarean section was 97.8% (88/90). The number of RDS cases was reduced gradually with the increase of gestational age and the constituent ratio of RDS at 39 w and at 40 w was significantly lower than that of 37 w and 38 w. By logistic regression analysis, the onset time of mechanical ventilation > 12 h independently predicted complications in RDS of term neonates (odds ratio 12.667, 95% confidence interval, i.e., CI 1.455 to 110.300, P = 0.021). Moreover, there was a significant difference in the admission age (t = 11.833, P = 0.001), severity of the radiological findings (t = 4.85, P = 0.028), PS application (t = 11.911, P = 0.002), the onset time of mechanical ventilation (t =10.051, P = 0.018), the ratio of PaO(2) to FIO(2) before mechanical ventilation (chi(2) = 4.184, P = 0.005), OI > 25 (t = 4.737, P = 0.03), duration of oxygen supplementation (chi(2) = 10.475, P = 0.001), systemic hypotension (t = 11.020, P = 0.01) and the length of hospital stay (t = 9.827, P = 0.002) between the two centers. CONCLUSION: Severe RDS can occur in term babies after elective caesarean section, gestational age at the time of elective caesarean section may also be important for RDS in term neonates. The onset time of mechanical ventilation > 12 h independently predicted complications in RDS of term neonates. The main complications of RDS in term neonates were PPHN, pulmonary air leaks and systemic hypotension. Early diagnosis, early intervention can significantly reduce the complications, alleviate the severity and shorten their time for oxygen therapy and their length of stay in NICU in term RDS infants.

Gram stain-specific-probe-based real-time PCR for diagnosis and discrimination of bacterial neonatal sepsis.

Sepsis is a serious disease with high mortality in newborns. It is very important to have a convenient and accurate method for pathogenic diagnosis of neonatal sepsis. We developed a method of simultaneous detection and Gram classification of clinically relevant bacterial pathogens causing sepsis directly from blood samples with Gram stain-specific-probe-based real-time PCR (GSPBRT-PCR). With GSPBRT-PCR, 53 clinically important strains representing 25 gram-positive and 28 gram-negative bacterial species were identified correctly with the corresponding Gram probe. The limits of the GSPBRT-PCR assay in serial dilutions of the bacteria revealed that Staphylococcus aureus could be detected at concentrations of 3 CFU per PCR and Escherichia coli at concentrations as low as 1 CFU per PCR. The GSPBRT-PCR assay was further evaluated on 600 blood specimens from patients with suspicion of neonatal sepsis and compared to the results obtained from blood cultures. The positive rate of the GSPBRT-PCR array was 50/600 (8.33%), significantly higher than that of blood culture (34/600; 5.67%) (P = 0.00003). When blood culture was used as a control, the sensitivity of GSPBRT-PCR was 100%, the specificity was 97.17%, and the index of accurate diagnosis was 0.972. This study suggests that GSPBRT-PCR is very useful for the rapid and accurate diagnosis of bacterial infection and that it can have an important impact on the current inappropriate and unnecessary use of antibiotics in the treatment of newborns.

[Detection of four human herpesviruses DNA and virus-specific IgM antibody in blood specimens of infants].

OBJECTIVE: To establish a restriction endonuclease pattern which could detect and differentiate four major human herpesviruses by polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), DNA cloning and sequence analysis. METHODS: A pair of primer, which was designed according to sequences in well-conserved regions of the DNA polymerase gene in human herpesviruses, was designed to amplify herpes simplex virus type 1 and 2 (HSVI/II), Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Sequences of the primers are as follows: P(1) (5'-CGACTTTGCCAGCCTGACC-3') and P(2) (5'-AGTCCGTGTCCCCGTAGATG-3'). DNA of four strains of standard herpesviruses were amplified by PCR, and further studied by DNA cloning, sequence analysis and RFLP. At last, the authors established the PCR-RFLP technique to differentiate the four different herpesviruses. Meanwhile, 75 clinical blood specimens from infants with suspected viral infection and 38 blood specimens from healthy children were evaluated for herpesviruses DNA or virus-specific IgM antibody by PCR-RFLP or by ELISA. RESULTS: The PCR amplified products of four human herpesviruses were from 510 bp to 592 bp in length and were analyzed for herpesvirus types with restriction endonuclease technique. The specificity and sensitivity of this PCR-RFLP were examined. There was no cross-reaction with Escherichia coli, Staphylococcus aureus, hepatitis B virus (HBV), Clostridium neoformans and human-genomic DNA and the lowest detection level was 0.1 fg DNA. Among 75 specimens, 23 were positive by PCR and the positive rate was 30.7%, including 13 for CMV, four for EBV, five for HSVII and one for HSVI after restriction enzyme digestion with BamHI and BstUI, while 10 were positive by ELISA and positive rate was 13.3%. All ELISA-positive specimens were likewise positive by PCR. Thirteen of 65 specimens that were ELISA-negative were tested positive by PCR. An infant with CMV infection was determined with viral DNA and virus-specific IgM antibody in blood at 3, 4 and 6 months after birth, respectively. The result showed that she was still CMV DNA-positive in blood whereas IgM antibody was positive only at month 3 after birth. None of the 38 control blood specimens was positive for herpesvirus by this PCR-RFLP or by ELISA. CONCLUSIONS: This PCR-RFLP technique was specific, sensitive, rapid and accurate in diagnosing herpesviruses infection in infants, and it could detect herpesviruses DNA in specimens which were negative for IgM antibody by ELISA.