Objective:To compare expression of iNOS on brain tissue in rats model of asphyxia death with other death groups and forensic significance.Methods:The production method of mechanical asphyxia death,hemorrhagic shock death,brain traumatic death and breaks the neck to execute group model;By means of immunohi stochemistry and image analysis technology to determinate the dead rats after each group at different times of iNOS in the brain tissue of expression.Results:iNOS in mechanical asphyxia death,hemorrhagic shock death and brain traumatic death have expressed,breaks the neck to execute was no expression and mechanical asphyxia death group was significantly higher levels than in all levels of other group,each group of 0h expression all slightly bottom to 6h,12h,24h,Also each group of 6h,12h,24h expression tends to the identical level.Conclusion:This discovery,in the 24 hours after the death of brain tissue iNOS expression can be inferred from the asphyxial death of a biological indicators.

Objective To investigate the phenotypic and genetic characteristics of the lysostaphin‐resistant Staphylococcus aureus variants induced by recombinant lysostaphin in vitro .Methods Three clinical isolates of S . aureus ,including two resistant to methicillin (MRSA ) and one susceptible to methicillin (MSSA ) were induced by treatment with sub‐MIC of recombinant lysostaphin via one‐step selection in vitro .Susceptibility of the variants to antibiotics were determined and compared with their parental strains .The full length of femABX genes was amplified by polymerase chain reaction and sequenced to identify the potential mutation sites in these genes .The growth‐curve in liquid medium and virulence in a mouse systemic infection model of both parental and variant strains were observed . Results The frequency of lysostaphin resistance in S . aureus was between 10-4 to 10-8 following induction by lysostaphin . Resistance to lysostaphin was associated with a significant decrease in growth rate in vitro and virulence in vivo ,as well as increased susceptibility toβ‐lactams evidenced by the M IC of β‐lactams against the variants as low as 1/4 000 to 1/2 of the M IC against their parental strains . Sequencing of f emA BX genes showed mutation in femA gene in both variants ,which resulted in a premature termination codon .Conclusions Resistance of S . aureus to lysostaphin may develop following induction by recombinant lysostaphin in vitro . The lysostaphin‐resistant S . aureus variants are characteristic of lower growth rate , decreased virulence ,and higher susceptibility to β‐lactams .

Objective To be good for the different working age midwives to carry out the same evaluation of the pregnant woman,we build and use the Episiotomy Evaluation Form for reducing the rate of episiotomy with ensuring the safety of mother and baby.Methods Consult relevant literature,combine clinical practice,discuss,report to the hospital ethics committee many times and at last it was made after approval.The details included:perineal lesions,perineum elasticity,perineal length,maternal coordination,gestational age,age,fetal distress degree,amniotic fluid situation,the weight of fetus estimated,the second time of labor and so on,to score by 0,1,3,5,20.A total of 600 patients with low risk of natural childbirth were randomly divided into observation group and control group according to method of random number table with 300 cases each.The observation group was graded according to the perineal incision evaluation and we operated according to its use method.The control group was judged according to the experience of midwife and subjective cognition.At last compared the effects on the mother and baby.Results The rates of lateral episiotomy and Ⅰ degree laceration were 15.00％ (45/300) and 63.00％ (189/300) in the observation group and 48.33％ (145/300) and 21.67％ (65/300) in the control group,respectively.The difference between the two groups was statistically significant (x2=16.238,21.507,P ＜ 0.05).There was no statistical difference in the perineal intact rate,median perineal incision rate,perineal Ⅱ degree laceration rate,severe perineal laceration,second stage of labor,postpartum hemorrhage 2 hours,neonatal asphyxia rate,incidence of neonatal birth injury (brachial plexus injury,clavicle fracture,etc.) and pelvic floor muscle strength of 42 days after delivery between the two groups (P ＞ 0.05).Conclusions By using the episiotomy evaluation form,we can improve the accuracy and homogeneity of the midwife's assessment about the episiotomy which is benefit to reduce rate of episiotomy.It is worth promoting in clinical practice but we should ensure the safety of maternal and child.

Objective:To investigate the incidence and risk factors of hypertensive disorders in pregnancy (HDP) in high altitude areas and their influence on maternal and infant outcomes.Methods:This was a retrospective case-control study. A total of 220 newborns were selected as the high altitude group, who were born to 216 mothers with HDP and admitted to the Neonatal Intensive Care Unit of the Lhasa People's Hospital from June 1, 2018, to June 1, 2020. The low altitude group consisted of 235 newborns born to 231 mothers with HDP and admitted to the Department of Neonatology of the Children's Hospital Affiliated to Beijing Capital Institute of Pediatrics from January 1, 2018, to December 31, 2021. Differences in the types of HDP between the two groups and the risk factors for the high incidence of preeclampsia-eclampsia and early-onset preeclampsia in high altitude area were analyzed. The influences of HDP in high and low altitude areas on maternal and infant outcomes were compared. Statistical analysis was performed using t-test, Mann-Whitney U test, Pearson Chi-square test, or continuous correction Chi-square test, and univariate and multivariate logistic regression analysis. Results:Maternal age and the proportions of primiparae and women of advanced age or having irregular prenatal examination were greater in the high altitude group than those in the low altitude group (all P<0.05). Besides, the incidence of early-onset preeclampsia, eclampsia, preeclampsia-eclampsia, and chronic hypertension complicated by preeclampsia were also higher in the high altitude group (all P<0.05). Multivariate logistic regression analysis showed that high altitude was a risk factor for the development of preeclampsia-eclampsia ( OR=4.437, 95% CI:2.582-7.626). Adverse pregnancy history ( OR=2.576, 95% CI:1.217-5.452) and irregular prenatal examination ( OR=2.862, 95% CI:1.412-5.800) were independent risk factors for early-onset preeclampsia in pregnant women in high altitude areas. Twin-pregnancy was a protective factor for early-onset preeclampsia in pregnant women in high altitude areas ( OR=0.183, 95% CI: 0.054-0.623). The incidence of maternal heart failure [7.9% (17/216) vs 0.4% (1/231), χ2=15.98], placental abruption [7.9% (17/216) vs 3.5% (8/231), χ2=4.11], hemolysis, elevated liver function and low platelet count syndrome [14.4% (31/216) vs 1.7% (4/231), χ2=24.64], premature delivery [86.1% (118/216) vs 73.6% (170/231), χ2=10.79], fetal growth restriction [52.3% (115/220) vs 18.7% (44/235), χ2=56.26], fetal distress [18.2% (40/220) vs 8.1% (19/235), χ2=10.26], neonatal asphyxia [29.5% (65/220) vs 11.1% (26/235), χ2=24.26], severe asphyxia [8.6% (19/220) vs 2.6% (6/235), χ2=8.10] and the proportion of neonates requiring mechanical ventilation within 24 h after birth [69.5% (153/220) vs 42.6% (100/235), χ2=33.54] as well as neonatal death within 7 d after birth [5.5% (12/220) vs 1.3% (3/235), χ2=6.22] in the high altitude group were significantly higher than those in the low altitude group (all P<0.05). Conclusion:High altitude is a risk factor for preeclampsia-eclampsia, and the adverse effects of HDP on mothers and infants are more severe in high altitude areas.

Objective:To explore the prognostic indicators and influencing factors of neonatal asphyxia in Tibet.Methods:From March 2019 to March 2020, the clinical data of 126 asphyxiated newborns admitted to the neonatology department of Lhasa People's Hospital were retrospectively studied. According to the prognosis, they were divided into good prognosis group and poor prognosis group, and the clinical characteristics of the two groups were compared. The predictive value of Apgar score after birth, arterial blood gas analysis within 6 hours [pH, alkali residue (BE)] and their combined detection on the prognosis of asphyxiated newborns was analyzed. Logistic regression analysis was used to analyze the related factors affecting the prognosis of asphyxiated newborns.Results:31 cases (24.6%) in the poor prognosis group and 95 cases (75.4%) in the good prognosis group. The Apgar score at 1, 5 and 10 minutes after birth and pH and BE within 6 hours in the poor prognosis group were significantly lower than those in the good prognosis group (all P<0.05). The incidence of meconium stained amniotic fluid, fetal intrauterine distress, brain damage, lung damage, myocardial damage, kidney damage, abnormal coagulation function and multiple organ damage after asphyxia in the good prognosis group were significantly higher than those in the good prognosis group (all P<0.05). The Apgar score at the 1, 5 and 10 minutes after birth combined with arterial blood gas analysis (pH and BE) within 6 hours after birth had high predictive value for the prognosis of asphyxiated newborns, with the area under receiver operating characteristic (ROC) curve of 0.79, sensitivity of 68.4% and specificity of 90.3%. Multivariate regression analysis showed that meconium stained amniotic fluid ( OR=4.501, 95% CI: 1.262-16.056), lung damage ( OR=5.004, 95% CI: 1.007-24.866) and brain damage ( OR=10.786, 95% CI: 2.726-42.673) were independent risk factors affecting the prognosis of neonatal asphyxia ( P<0.05). Conclusions:In Tibet, there are many factors affecting the poor prognosis of neonatal asphyxia. High attention and intervention should be given to mothers in perinatal period and asphyxiated newborns in order to reduce the incidence of poor prognosis of neonatal asphyxia.

The objective of this study was to investigate the genetic basis of high level aminoglycoside resistance in Acinetobacter baumannii clinical isolates from Beijing, China. 173 A. baumannii clinical isolates from hospitals in Beijing from 2006 to 2009 were first subjected to high level aminoglycoside resistance (HLAR, MIC to gentamicin and amikacin>512 µg/mL) phenotype selection by broth microdilution method. The strains were then subjected to genetic basis analysis by PCR detection of the aminoglycoside modifying enzyme genes (aac(3)-I, aac(3)-IIc, aac(6')-Ib, aac(6')-II, aph(4)-Ia, aph(3')-I, aph(3')-IIb, aph(3')-IIIa, aph(3')-VIa, aph(2″)-Ib, aph(2″)-Ic, aph(2″)-Id, ant(2″)-Ia, ant(3″)-I and ant(4')-Ia) and the 16S rRNA methylase genes (armA, rmtB and rmtC). Correlation analysis between the presence of aminoglycoside resistance gene and HLAR phenotype were performed by SPSS. Totally 102 (58.96%) HLAR isolates were selected. The HLAR rates for year 2006, 2007, 2008 and 2009 were 52.63%, 65.22%, 51.11% and 70.83%, respectively. Five modifying enzyme genes (aac(3)-I, detection rate of 65.69%; aac(6')-Ib, detection rate of 45.10%; aph(3')-I, detection rate of 47.06%; aph(3')-IIb, detection rate of 0.98%; ant(3″)-I, detection rate of 95.10%) and one methylase gene (armA, detection rate of 98.04%) were detected in the 102 A. baumannii with aac(3)-I+aac(6')-Ib+ant(3″)-I+armA (detection rate of 25.49%), aac(3)-I+aph(3')-I+ant(3″)-I+armA (detection rate of 21.57%) and ant(3″)-I+armA (detection rate of 12.75%) being the most prevalent gene profiles. The values of chi-square tests showed correlation of armA, ant(3″)-I, aac(3)-I, aph(3')-I and aac(6')-Ib with HLAR. armA had significant correlation (contingency coefficient 0.685) and good contingency with HLAR (kappa 0.940). The high rates of HLAR may cause a serious problem for combination therapy of aminoglycoside with β-lactams against A. baumannii infections. As armA was reported to be able to cause high level aminoglycoside resistance to most of the clinical important aminoglycosides (gentamicin, amikacin, tobramycin, etc), the function of aminoglycoside modifying enzyme gene(s) in A. baumannii carrying armA deserves further investigation.

As d-amino acids play important roles in the physiological metabolism of bacteria, combination of d-amino acids with antibiotics may provide synergistic antibacterial activity. The aim of the study was to evaluate and activity of d-serine alone and in combination with -lactams against methicillin-resistant (MRSA) strains, and to explore the possible sensitization mechanisms. The activity of d-serine, -lactams alone and in combinations was evaluated both by standard MICs, time-kill curves and checkerboard assays, and by murine systemic infection model as well as neutropenic thigh infection model. An synergistic effect was demonstrated with the combination of d-serine and -lactams against MRSA standard and clinical strains. Importantly, the combinations enhanced the therapeutic efficacy in the animal models as compared to -lactam alone groups. Initial mechanism study suggested possible revision of d-alanine-d-alanine residue to d-alanine-d-serine in peptidoglycan by adding of d-alanine in the medium, which may cause decreased affinity to PBPs during transpeptidation. In conclusion, d-serine had synergistic activity in combination with -lactams against MRSA strains both and . Considering the relatively good safety of d-serine alone or in combination with -lactams, d-serine is worth following up as new anti-MRSA infection strategies.

Polymyxin B and polymyxin E (colistin) are presently considered the last line of defense against human infections caused by multidrug-resistant Gram-negative organisms such as carbapenemase-producer Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae. Yet resistance to this last-line drugs is a major public health threat and is rapidly increasing. Polymyxin S₂ (S₂) is a polymyxin B analogue previously synthesized in our institute with obviously high antibacterial activity and lower toxicity than polymyxin B and colistin. To predict the possible resistant mechanism of S₂ for wide clinical application, we experimentally induced bacterial resistant mutants and studied the preliminary resistance mechanisms. Mut-S, a resistant mutant of K. pneumoniae ATCC BAA-2146 (Kpn2146) induced by S₂, was analyzed by whole genome sequencing, transcriptomics, mass spectrometry and complementation experiment. Surprisingly, large-scale genomic inversion (LSGI) of approximately 1.1 Mbp in the chromosome caused by IS26 mediated intramolecular transposition was found in Mut-S, which led to mgrB truncation, lipid A modification and hence S₂ resistance. The resistance can be complemented by plasmid carrying intact mgrB. The same mechanism was also found in polymyxin B and colistin induced drug-resistant mutants of Kpn2146 (Mut-B and Mut-E, respectively). This is the first report of polymyxin resistance caused by IS26 intramolecular transposition mediated mgrB truncation in chromosome in K. pneumoniae. The findings broaden our scope of knowledge for polymyxin resistance and enriched our understanding of how bacteria can manage to survive in the presence of antibiotics.