As the biggest tissue of human body, skin is the first barrier of resisting external aggression. Collagen is one of important parts of the skin, which could not only affect the aesthetics of skin, but also influence the health and normal function of skin. It is the great significance to find ways that could inhibit the loss of collagen. The mechanisms of the collagen degradation in skin are complex and multifaceted. Natural bioactive products have unique advantages in treating the loss of collagen, which have multi-targets and mechanisms. In this review, the mechanisms of skin collagen degradation are discussed, and the research progress of natural bioactive products in resisting skin aging through promoting collagen synthesis are reviewed, in order to provide references for futural research.

Objective To investigate the pharmacokinetics of cyclosporine(CsA) in type 1 diabetes of rats.Methods Rats with type 1 diabetes were induced by intraperitoneal administration of 65 mg· kg-1 streptozotocin (STZ).Pharmacokinetics of CsA (10 mg· kg-1) was compared between diabetic and normal rats on the 5 weeks after STZ injection.Concentration of CsA in whole blood was measured by enzyme multiplied immunoassay technique.Results Type 1 diabetes rats were successfully induced as the fasting blood glucose levels exceeded 11.1 mmol · L-1 after STZ injection for 1 week.Beside glucose,total cholesterol (TC) and triacylglycerol (TG) in serum of diabetic rats were significantly higher than those in normal rats after STZ injection for 5 weeks.Unlike normal rats,the pharmacokinetics of CsA in diabetic rats exhibited a double peak after oral administration.The Tmax and Cmax were lower in diabetic rats than normal rats,although without statistical differences as follows:Tmaxwas (3.3±1.6),(3.2 ±2.5) h,Cmax was (579.0±208.5),(453.0 ± 104.8) ng· mL-1 in normal and diabetic rats.Compared with normal rats,AUC and t1/2 of CsA in diabetic rats decreased significantly,which were 0.51 and 0.70 times those of normal rats,respectively;AUC was (7343.2 ± 2333.7),(3729.7 ± 1106.6) h ·ng · mL-1,t1/2 was (8.5 ± 1.5),(6.0 ± 0.9) h in normal and diabetic rats.Conclusion The oral pharmacokinetics of CsA was significantly different in type 1 diabetic rat model compared to normal controls,which should be taken into consideration in clinical medication.

Objective To analyze horizontal transmission patterns of Streptococcus mutans among caries-active preschool children for early interventions of dental caries. Methods Plaque samples obtained from 20 caries-active preschool children between 4 and 5 years of age were cultured under anaerobic conditions for isolating S. mutans, which were identified by morphological and biochemical analyses and PCR using primers homologous to the surface protein glucosyltransferase B (gtfB). The genotypes of the isolated S. mutans strains were determined by arbitrarily primed PCR (AP-PCR). Results Of the 200 S. mutans isolates obtained, 19 were excluded by biochemical analysis, and the remaining 181 isolates were identified as S. mutans by PCR with primers of gtfB, showing 37 different genotypes as identified by AP-PCR. Six children were found to carry S. mutans of a single genotype, 11 carried 2 genotypes, 2 had 3 genotypes, and 1 had 4 genotypes;2 children from different classes were found to carry S. mutans of the same single genotype. Conclusion We identified 37 genotypes of S. mutans in these caries-active preschool children, among whom horizontal transmissions of the strains were not found.

Objective To analyze horizontal transmission patterns of Streptococcus mutans among caries-active preschool children for early interventions of dental caries. Methods Plaque samples obtained from 20 caries-active preschool children between 4 and 5 years of age were cultured under anaerobic conditions for isolating S. mutans, which were identified by morphological and biochemical analyses and PCR using primers homologous to the surface protein glucosyltransferase B (gtfB). The genotypes of the isolated S. mutans strains were determined by arbitrarily primed PCR (AP-PCR). Results Of the 200 S. mutans isolates obtained, 19 were excluded by biochemical analysis, and the remaining 181 isolates were identified as S. mutans by PCR with primers of gtfB, showing 37 different genotypes as identified by AP-PCR. Six children were found to carry S. mutans of a single genotype, 11 carried 2 genotypes, 2 had 3 genotypes, and 1 had 4 genotypes;2 children from different classes were found to carry S. mutans of the same single genotype. Conclusion We identified 37 genotypes of S. mutans in these caries-active preschool children, among whom horizontal transmissions of the strains were not found.

OBJECTIVETo analyze horizontal transmission patterns of Streptococcus mutans among caries-active preschool children for early interventions of dental caries.

METHODSPlaque samples obtained from 20 caries-active preschool children between 4 and 5 years of age were cultured under anaerobic conditions for isolating S. mutans, which were identified by morphological and biochemical analyses and PCR using primers homologous to the surface protein glucosyltransferase B (gtfB). The genotypes of the isolated S. mutans strains were determined by arbitrarily primed PCR (AP-PCR).

RESULTSOf the 200 S. mutans isolates obtained, 19 were excluded by biochemical analysis, and the remaining 181 isolates were identified as S. mutans by PCR with primers of gtfB, showing 37 different genotypes as identified by AP-PCR. Six children were found to carry S. mutans of a single genotype, 11 carried 2 genotypes, 2 had 3 genotypes, and 1 had 4 genotypes; 2 children from different classes were found to carry S. mutans of the same single genotype.

CONCLUSIONWe identified 37 genotypes of S. mutans in these caries-active preschool children, among whom horizontal transmissions of the strains were not found.

Child, Preschool ; Dental Caries ; microbiology ; Dental Plaque ; Genotype ; Glucosyltransferases ; Humans ; Polymerase Chain Reaction ; Streptococcal Infections ; transmission ; Streptococcus mutans ; classification

OBJECTIVETo select and identify ssDNA aptamers specific to Streptococcus mutans strains with different cariogenicity isolated from clinical specimens.

METHODSSubtractive SELEX technology targeting the whole intact cells was used to screen for ssDNA aptamers specific to the clinical isolates Streptococcus mutans strains with different cariogenicity. Radioactive isotope, flow cytometry, gene cloning and sequencing, MEME online software and RNA structure analysis software were employed to analyze the first and secondary structures of the aptamers and identify the screened aptamers.

RESULTSDetection by radioactive isotope showed sufficient pool enrichment after 9 rounds of subtractive SELEX. Flow cytometry showed that the selected aptamers H1, H16, H4, L1, L10 and H19 were capable of binding specifically with highly cariogenic Streptococcus mutans strains but not with strains with a low cariogenicity. The aptamer H19 had the strongest binding capacity to highly cariogenic Streptococcus mutans strains, with a dissociation constant of 69.45∓38.53 nmol/L.

CONCLUSIONWe have obtained the ssDNA aptamers specific to the clinical isolates of highly cariogenic Streptococcus mutans strains.

Aptamers, Nucleotide ; genetics ; Cloning, Molecular ; DNA Primers ; Dental Caries ; microbiology ; Gene Library ; Humans ; Nucleic Acid Conformation ; SELEX Aptamer Technique ; Species Specificity ; Streptococcus mutans ; classification ; genetics ; isolation & purification

Objective To investigate antimicrobial resistance among nosocomial gram-negative bacilli in 2016 across China.Methods About 1 394 consecutive and non-repetitive gram-negative bacilli were isolated from 14 teaching hospitals from March to August in 2016 across China.All of these isolates were sent to the central laboratory for reidentification and susceptibility testing.The minimal inhibitory concentration(MICs)of meropenem and other antibacterial agents were determined by agar dilution method.The data were analyzed by using WHONET-5.6 software.Results The activity of antimicrobial agents against Enterobacteriaceae was as follows in descending order of susceptible rate: meropenem (95.2%,891/936), amikacin (94.6%,885/936), ertapenem (92.1%,862/936), piperacillin/tazobactam (88.1%,825/936), imipenem (88.0%,823/936), cefoperazone-sulbactam (83.1%,778/936), cefepime (72.2%,676/936), cefiazidime (72.2%,676/936), levofloxacin(68.8%,644/936), ciprofloxacin (63.2%,592/936), minocyline (62.9%,589/936), cefiriaxone (54.9%,514/936), cefotaxime (54.0%,505/936), cefoxitin (44.3%,415/936).The sensitivities of E.coli to carbapenems, amikacin, piperacillin-tazobactam, polymyxin B and cefoperazone-sulbactam were over 80%.The more sensitive antibiotic to Klebsiella pneumoniae was polymyxin B (99.0%), followed by amikacin (84.9%), meropenem (84.4%) and imipenem (82.0%).The prevalence of extended-spectrum β-lactamase was 62.8%(137/218)in Escherichia coli and 28.3%(58/205)in Klebsiella pneumonia.The activity of antimicrobial agents against E.cloacae, E.aerogenes and Citrobacter freundii was as follows in descending order of susceptible rate: meropenem (97.0%-98.5%), amikacin (95.8%-98.3%), imipenem (94.5%-97.5%), polymyxin B (96.4%-100%), cefoperazone-sulbactam (76.5%-90.0%), ertapenem (73.3%-90.1%), piperacillin/tazobactam (82.4%-88.3%).The most active agents against Pseudomonas aeruginosa were polymyxinB (100%), followed by amikacin (89.3%) and ciprofloxacin (82.4%).The most active agents against Acinetobacter baumannii were polymyxinB (100%).The sensitivities of Acinetobacter baumannii to meropenem, imipenem, minocycline and cefoperazone-sulbactam were 20.3%(39/202), 19.3%(41/202), 66.3%(134/202) and 24.8%(50/202), respectively.Conclusions Carbapenems remain high sensitive against Enterobacteriaceae.Controlling carbapenem resistant Klebsiella pneumoniae is urgent.Drug antimicrobial resistance in A.baumanni is a still serious problem.

Objectives:To describe and summarize international evidences on policies and programs for training health personnel in rural areas,to identify best practice to increase health manpower in rural areas, and to provide references for China's policy of targeted admission program. Methods:This is a literature review based research. 48 literatures in Chinese and English were selected about the training of health professionals in rural areas at home and a-broad. Thematic framework approach was applied to review and analyze the related strategies and practices,and les-sons learned. Results: Common measures to train health personnel in rural areas included: enrollment of students with a rural background,tutoring system in medical training,internship in rural health institutions, financial incen-tives,and compulsory rural services after graduation. Lessons learnt:(1) adequate financial resources are a prereq-uisite for smooth program implementation;(2) Good project management and evaluation are critical aspects of effec-tive project implementation;(3) choosing the right combination of various practices to implement such projects can improve effectiveness. Conclusions:The policy of targeted admission program is suitable for China's current situation. Meanwhile,international experiences can provide valuable lessons to improve China's program design and implemen-tation and these include:increasing capital investment,strengthening management and evaluation,and strengthening sector cooperation to further improve targeted admission program.

Objective To investigate the antimicrobial resistance profile of the clinical isolates collected from selected hospitals across China. Methods Twenty-nine general hospitals and five children's hospitals were involved in this program. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were interpreted according to CLSI 2017 breakpoints. Results A total of 190 610 clinical isolates were collected from January to December 2017, of which gram negative organisms accounted for 70.8％ (134 951/190 610) and gram positive cocci 29.2％ (55 649/190 610). The prevalence of methicillin-resistant strains was 35.3％ in S. aureus (MRSA) and 80.3％ in coagulase negative Staphylococcus (MRCNS) on average. MR strains showed much higher resistance rates to most of the other antimicrobial agents than MS strains. However, 91.6％ of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 86.2％ of MRCNS strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains showed much lower resistance rates to most of the drugs tested (except chloramphenicol) than E. faecium. Vancomycin-resistant Enterococcus (VRE) was identified in both E. faecalis and E. faecium. The identified VRE strains were mainly vanA, vanB or vanM type based on phenotype or genotype. The proportion of PSSP or PRSP strains in the non-meningitis S.pneumoniae strains isolated from children decreased but the proportion of PISP strains increased when compared to the data of 2016. Enterobacteriaceae strains were still highly susceptible to carbapenems. Overall, less than 10％ of these strains (excluding Klebsiella spp.) were resistant to carbapenems. The prevalence of imipenem-resistant K. pneumoniae increased from 3.0％ in 2005 to 20.9％ in 2017, and meropenem-resistant K. pneumoniae increased from 2.9％ in 2005 to 24.0％ in 2017, more than 8-fold increase. About 66.7％ and 69.3％ of Acinetobacter (A. baumannii accounts for 91.5％) strains were resistant to imipenem and meropenem, respectively. Compared with the data of year 2016, P. aeruginosa strains showed decreasing resistance rate to carbapenems. Conclusions Bacterial resistance is still on the rise. It is necessary to strengthen hospital infection control and stewardship of antimicrobial agents. The communication between laboratorians and clinicians should be further improved in addition to surveillance of bacterial resistance.