Determination of active polypeptides in breast milk and its preventive effect on necrotizing enterocolitis / 中华实用儿科临床杂志

Objective To analyze the biological activity of bioactive peptides in human breast milk and to find the polypeptides so as to investigate the preventive and therapeutic effects of breast milk-derived bioactive peptides on neonatal necrotizing enterocolitis(NEC).Methods Six mothers who gave birth to preterm neonates were enrolled in this study and 5 mL of their breast milk secreted within 2-5 postnatal days were collected for 6 times and blended subsequently.Bioactive peptides from maternal milk of the preterm infants were separated by ultrafiltration and analyzed by using tandem mass spectrometry.Polypeptides possibly with biological function were screened out by using bioinformatics software and the protein function cluster online analysis software was used to predict the polypeptides associated with infection according to the biological function of their precursor proteins.The ATCC25922,an Escherichia coli strain commonly associated with infection in NEC and drug solution (sulbactarr/cefoperazone) were used to conduct the drug susceptibility testing and bactericidal kinetics testing,so as to verify the antibacterial effects of bioactive peptides in the breast milk.Results Four thousand three hundred and eleven peptides contained in breast milk were identified successfully,of which 1 370 were non-differential peptides,and 188 peptides possibly with biological activity and 11 peptides were associated with infection.The peptide compound in the breast milk had antimicrobial activity and bactericidal power against Escherichia coli.Conclusions The active peptide compounds in the breast milk have antimicrobial activity,which play an important role in the prevention of NEC.Finding the true antimicrobial peptides with in vivo and in vitro biological activity by using antimicrobial spectrum test is expected.

Detection and sequential analysis of Granulocytic ehrlichia 444-Epank gene / 中华流行病学杂志

<p><b>OBJECTIVE</b>To provide further pathogenic evidence of Granulocytic ehrlichia infection in China.</p><p><b>METHODS</b>Specific primers derived from 444-Epank gene were used to amplify Granulocytic ehrlichia DNA from specimens of ticks, animals and human blood. PCR products of ticks were cloned and sequenced.</p><p><b>RESULTS</b>444 bp specific DNA fragments were amplified from 2 of 62 pools of Ixodes persulcatus collected from Heilongjiang province and 1 of 129 blood specimens from forest workers in Inner Mongolia. Eight animal specimens were negative. PCR products from ticks were then cloned and sequenced. It differed at 23 positions in comparison to American strain (AF047897) with 94.9% homology. The homology of deduced ammonia was 88.44%.</p><p><b>CONCLUSION</b>Our findings further confirmed that Granulocytic ehrlichia infection did exist in China.</p>

Exploratory study on natural focus and its causative agent of genotype of Lyme disease by polymerase chain reaction in the forest areas of Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To learn the existence of natural focus of Lyme disease and its distribution.</p><p><b>METHODS</b>A semi-nested polymerase chain reaction (PCR) method was developed for detection and genotyping of Borrelia burgdorferi on basis of outer surface protein A (OspA) gene. Ticks and mice collected from 6 forest areas in Beijing were detected with above methods. The positive PCR products were cloned and sequenced. The sequences were compared with published sequences for homology. IFA as used to detect IgG antibody on Borrelia burgdorferi. Lyme disease spirochete were isolated from H. longicornis were also attempted.</p><p><b>RESULTS</b>B. Burgdorferi sensu lato were detected from 939 ticks and 250 mice specimens collected from above 6 study sites using primer pairs OA(1)/OA(4) and SL/OA(4). Only the specimens collected from Dongling mountain showed positive amplification. One in three adult Ixodes persulcatus with one of 57 nymph Ixodes persulcatus showed positive while 9 of 119 (7.56%) mice specimens showed positive, of which 8 were B. grinii and one B. afzelii. In this study, we attempted to isolate B. burgdorferi sensu lato strains from 160 H. longicornis ticks (20/group) but failed. Serological survey showed a 9.1% (5/55) infection rate with B. burgdorferi sensu lato in the mice of Dongling mountain forest areas.</p><p><b>CONCLUSIONS</b>The natural focus of Lyme disease including B. garinii and B. afzelii might have existed in Dongling mountain of Mentougou district, Beijing. Ixodes persulcatu and mice may serve as vectors and reservoirs, respectively.</p>