[Effects of four efflux pump inhibitors on the activities of clarithromycin against Mycobacterium abscessus]

Objective: To detect the effects of four efflux pump inhibitors on the minimum inhibitory concentration of clarithromycin (CLA) against Mycobacterium abscessus (M. abscessus) in vitro, and to explore the role of efflux pump in CLA resistance of M. abscessus. Methods: Four frequently-used efflux pump inhibitors (Carbonyl Cyanide 3-chlorophenylhydrazone, CCCP, N, N'-dicyclohexylcarbodiimide, DCC, Verapamil, VP, Reserpine, RSP) were evaluated in this study. The minimum inhibitory concentration (MIC) values of clarithromycin against M. abscessus reference strain and 60 clinical strains with or without efflux pump inhibitors were detected by Alamar Blue method. Sequence analysis of erm(41) and rrl genes known to be associated with CLA resistance in M. abscessus was performed to analyze the correlation between the effect of efflux pump inhibitors on MIC and mutation of resistance-related genes. Results: CCCP, DCC, VP and RSP could reduce the MIC of M. abscessus to CLA, and the effect of RSP was weaker than the other three efflux pump inhibitors. Among the sixty M. abscessus clinical strains, ten strains were resistant to clarithromycin, seven of which had rrl gene mutation. The CLA resistance rate of smooth phenotype isolates was higher than that of rough phenotype isolates. At 3 day of clarithromycin incubation, the MICs of resistant strains were all reduced by efflux pump inhibitors. Compared with the strains with rrl gene mutation, efflux pump inhibitors had a greater effect on the strains without rrl gene mutation. At 14 day of clarithromycin incubation, 83% of M. abscessus subsp. abscessus, were induced to be resistant, and all of them were T28 sequence type of erm(41). With the occurrence of induced drug resistance, the effect of efflux pump inhibitor on CLA MIC decreased. Efflux pump inhibitors had no statistically significant diffence in the effect of effcux pump inhibitors on CLA MIC levels in different phenotypes of isolates. Conclusions: Efflux pump is involved in the resistance process of M. abscessus to CLA. Efflux pump inhibitors reduce the drug resistance to clarithromycin against M. abscessus in different degrees. The use of efflux pump inhibitors may provide a new way to alleviate the drug resistance of M. abscessus.

Effects of auricular acupressure on chemotherapy-induced nausea and vomiting in breast cancer patients: a preliminary randomized controlled trial

BACKGROUND

Auricular acupressure (AA) has been viewed as a promising approach to managing chemotherapy-induced nausea and vomiting (CINV) but relevant research evidence has been inconclusive. This study aimed to examine the effects of AA on CINV in breast cancer (BC) patients undergoing chemotherapy.

METHODS

A preliminary randomized controlled trial was conducted in 114 BC patients. Participants were randomly allocated to a true AA group (n = 38), a sham AA group (n = 38), and a standard care group (n = 38). All the participants were provided with standard antiemetic treatment and care, while the true AA group and the sham AA group received an additional 5-day true AA and a 5-day sham AA, respectively. Acute and delayed CINV were assessed by using the MASCC Antiemesis Tool (MAT), anticipatory nausea and vomiting were measured by the Index of Nausea, Vomiting, and Retching (INVR), and patients' quality of life (QoL) was evaluated by the Functional Assessment of Cancer Therapy-Breast (FACT-B).

RESULTS

Both the true and sham AA groups reported improved CINV outcomes than the standard care group, with the true AA demonstrating larger effects than the sham comparison. The true and sham AA groups had higher complete response (CR) rates of CINV when compared with the standard care group, with the difference in the CR of acute CINV achieving statistical significance (p = 0.03). Both the true and sham AA groups demonstrated lower incidence and severity of acute CINV compared with the standard care group with the among-group difference reaching statistical significance for the occurrence (p = 0.04) and severity (p = 0.001) of acute nausea. No significant differences in anticipatory CINV and QoL were found among the groups.

CONCLUSION

The use of AA plus standard antiemetic treatment and care was superior to the use of standard antiemetic treatment and care alone in managing CINV among BC patients receiving chemotherapy. The antiemetic effects of AA were identified to be more profound in improving acute CINV, particularly acute nausea. The antiemetic effects of AA were deemed to be a mixture of specific treatment effects and placebo effects, and the placebo effects were very large and even reached clinical significance.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT02403037 ; Registered March 31, 2015.

[Analysis of lactate dehydrogenase gene polymorphisms and prediction of B cell epitopes in four human Plasmodium species]

OBJECTIVE

To analyze the polymorphism of Plasmodium lactate dehydrogenase (pLDH) gene and predict B-cell epitopes in pLDH peptides in four species of human malaria parasites.

METHODS

The blood samples and epidemiological characteristics were collected from malaria cases in Yunnan Province registered in the National Notifiable Disease Report System. The pLDH genes of four human Plasmodium species were amplified using nested PCR assay and sequenced. The polymorphisms of pLDH genes was analyzed using the software MEGA version 7.0.26 and DnaSP version 5.10, and the B-cell epitopes were predicted in pLDH peptides using the Immune Epitope Database (IEDB).

RESULTS

The sequences of P. vivax LDH (PvLDH), P. falciparum LDH (PfLDH), P. ovale LDH (PoLDH) and P. malariae LDH (PmLDH) genes were obtained from 153, 29, 17 and 11 blood samples from patients with P. vivax, P. falciparum, P. ovale and P. malariae malaria, respectively, which included 15, 2, 4 and 2 haplotypes and had a nucleotide diversity (π) of 0.104. A high level of intra-species differentiation was seen in the PoLDH gene (π = 0.012), and the π values were all < 0.001 for PvLDH, PfLDH and PmLDH genes. Active regions of B-cell antigen were predicted in the pLDH peptide chain of four human malaria parasites, of 4 to 5 in each chain, and the activity score was approximately 0.430. Among these peptide chains, the "86-PGKSDKEWNRD-96" short-peptide was a B-cell epitope shared by all four species of human malaria parasites, and the "266-GQYGHS (T)-271" short-peptide was present in PvLDH and PoLDH peptide chains, while "212-EEVEGIFDR-220" was only found in the PvLDH peptide chain, and "208-LISDAE-213" was only seen in the PfLDH peptide chain.

CONCLUSIONS

The PoLDH gene polymorphism may be derived from the weak negative purification selection, while PvLDH, PfLDH and PmLDH genes may maintain a relatively conservative state. There may be two B-cell epitopes "212-EEVEGIFDR-220" and "208-LISDAE-213" in the proximal region of the C terminal in the pLDH peptide chain, which is feasible to differentiate between P. vivax and P. falciparum infections.

Primary intratracheal schwannoma misdiagnosed as severe asthma in an adolescent: A case report

BACKGROUND

Primary intratracheal schwannoma is an extremely rare type of benign airway tumor, especially in adolescents. The presenting symptoms are typically prolonged cough and wheezing that can be misdiagnosed as asthma in adolescent patients.

CASE

A 16-year-old adolescent girl admitted to a local hospital with symptoms of an irritating cough and wheezing was diagnosed with bronchial asthma and treated with budesonide and formoterol. Over the next year, the patient's wheezing and coughing symptoms gradually worsened and the antiasthma treatment was ineffective. One week prior to this admission, the patient developed dyspnea after catching a cold and was transferred to our hospital with a diagnosis of severe asthma. However, chest computed tomography and bronchoscopy showed a mass in the trachea. Primary intratracheal schwannoma was diagnosed by biopsy. Her symptoms were relieved by endoscopic resection by electrosurgical snaring combined with argon plasma coagulation. No relapse occurred during an 18 mo follow-up.

CONCLUSION

Primary intratracheal schwannoma should be considered in the differential diagnosis in adolescents with recurrent asthma-like attacks.

[Mycobacterium xenopi pulmonary disease:report of 3 cases and literature review]

Objective: To analyze the clinical manifestations, radiographic characteristics and prognosis of Mycobacterium xenopi pulmonary disease, in order to improve diagnosis and treatment of the disease. Methods: Using "Mycobacterium xenopi, pulmonary disease" as the search term, from February 15, 2007 to February 21, 2021, a total of 1 264 cases were retrieved in the PubMed database. In the Wanfang database, using "Mycobacterium xenopi, pulmonary disease" as the search term, from February 15, 2007 to February 21, 2021, no related document was retrieved. In the CNKI database, "Mycobacterium xenopi, pulmonary disease" was used as the search term, and one relevant case report was retrieved, but did not meet the diagnostic criteria of Mycobacterium xenopi pulmonary disease issued by American Thoracic Society in 2007. The 1 264 cases from the literature and 3 cases of our institution were used for review. Results: Our 3 cases were elderly males complaining of cough and expectoration, and had underlying lung diseases. The imaging examination showed cavitary lesions. All of them had positive sputum smear for acid-fast bacillus and negative Xpert MTB/RIF examination. Mycobacterium xenopi was isolated at least 2 times from sputum samples. Although prescribed with chemotherapy, case 1 and case 2 died 4 years and 2 years later, respectively, after the diagnosis. Case 3 got sputum conversion, symptom improvement and radiographic responses after 30-month chemotherapy. Conclusions: The clinical manifestations of Mycobacterium xenopi pulmonary disease are atypical. For patients with positive sputum smear for acid-fast bacillus and negative Xpert MTB/RIF examination and conventional mycobacterial culture, Mycobacterium xenopi pulmonary disease should be considered. The disease deserves further attention from clinicians due to poor prognosis.

[In vitro evaluation of the antibacterial activity of nemonoxacin against Mycobacterium tuberculosis, Mycobacterium intracellulare and Mycobacterium abscessus]

Objective: To test the in vitro antibacterial activity of nemonoxacin against clinically isolates of Mycobacterium tuberculosis complex(MTBC), Mycobacterium intracellulare(MI) and Mycobacterium abscessus(MA). Methods: Totally 128, 80 and 50 isolates of MTBC, M.intracellulare and M.abscessus were tested, respectively. The minimum inhibitory concentrations (MICs) of nemonoxacin and levofloxacin against the strains of the three most frequently isolated mycobacterium species were measured by double dilution method with micro-well plate. Results: The MICs of 104(81.2%) strains of MTBC isolates against levofloxacin were ≤ 1 μg/ml. Whereas 112 (87.5%) strains of MTBC isolates had MICs against nemonoxacin than>1 μg/ml, furthermore, the MICs of 88(68.8%)strains of MTBC isolates against nemonoxacin were≥4 μg/ml. The median MIC of M. intracellulare isolates against levofloxacin and nenofloxacin were 16 and 32 μg/ml, separately, while were 16 μg/ml and 8 μg/ml for M. abscessus, respectively. The ratios of nemonoxacin MIC/levofloxacin MIC of M. abscessus were between 0.125-1.000. Conclusions: Nemonoxacin presented weaker inhibitory activity than levofloxacin against M. tuberculosis, whereas it had better activity than levofloxacin against M. abscessus.

[Antimicrobial susceptibility and genotyping of Mycobacterium intracellulare]

Objective: To investigate the antimicrobial susceptibility and genotyping of Mycobacterium intracellulare. Methods: A total of 150 M. intracellulare isolates were collected. The susceptibility against 15 antimicrobial agents widely used for treatment of non-tuberculosis mycobacteria (NTM) infections, was tested by broth microdilution assay. Variable number of tandem repeats (VNTR) assay was also performed using the 16-loci genotyping method. Results: The drug susceptibility test revealed that clarithromycin (97.3%, 146/150), moxifloxacin (94.0%, 141/150) and amikacin (90.0%, 135/150) had the best antimicrobial activities in vitro against the M. intracellulare isolates. Secondly, 75.3%(113/150), 64.0%(96/150), 52.7%(79/150) and 8.7%(13/150) of the strains were susceptible to rifampicin, linezolid, capreomycin, and ethambutol, respectively. The MIC(50) and MIC(90) values of the 3 injectable anti-tuberculosis drugs were as follows: amikacin 4 mg/L and 16 mg/L, streptomycin 4 mg/L and 16 mg/L, capreomycin 8 mg/L and 16 mg/L. The MIC(50) and MIC(90) values of the 5 different fluoroquinolones were 0.5 mg/L and 2 mg/L for moxifloxacin , 1 mg/L and 8 mg/L for ciprofloxacin, 1 mg/L and 8ug/ml for levofloxacin, 2 mg/L and 16 mg/L for antoflolxacin, 2 mg/L and 16 mg/L for ofloxacin. The Hunter-Gaston Discriminatory Index (HGDI) value for the 16-loci VNTR typing of M. intracellulare isolates was 0.994. VNTR differentiated the 150 isolates into 21 clusters and acquired a total of 121 unique patterns. Drug resistance profile was not independently associated with cluster strains. Conclusions: Clarithromycin, moxifloxacin and amikacin had the best antimicrobial activities in vitro against M. intracellulare isolates. The 16-loci VNTR typing revealed a highly discriminatory power and drug resistance profile was not independently associated with cluster strains.

[Evaluation of a high-intensity fluorescent fluorophage method for diagnosis of drug-resistance in tuberculosis]

Objective: To evaluate the high-intensity green fluorescent protein fluorophage Φ(2)GFP10 method for drug susceptibility testing of tuberculosis for isoniazid(INH), rifampin(RIF), and streptomycin(SM). Methods: A total of 128 clinical M. tuberculosis strains were isolated from patients with suspected drug-resistant tuberculosis visiting Beijing Chest Hospital (Beijing, China) from April to June 2014.All of the isolates were tested by the phage assay, while conventional drug susceptibility tests were performing on Lwenstein-Jensen culture medium as reference. Results: The sensitivities of Φ(2)GFP10 assay for INH, RIF, and SM resistance detection were 100.0%, 98.1%(53/54), and 92.6%(50/54), respectively, while their specificities were 84.8%(56/66), 91.9%(68/74), and 91.9%(68/74), respectively. The agreement between the phage assay and the conventional assay for detecting INH, RIF, and SM resistance was 0.92, 0.95 and 0.92, respectively. The Φ(2) GFP10-phage assay could be done within 2 days for RIF and SM, and 3 days for INH. Conclusions: The Φ(2)GFP10-phage method for drug susceptibility test is very sensitive and specific. The method has the potential to be a valuable, rapid and economical screening method for detecting drug-resistant tuberculosis.

[Discriminatory power of variable number on tandem repeats loci for genotyping Mycobacterium tuberculosis strains in China]

Objective: Using the standard genotype method, variable number of tandem repeats (VNTR), we constructed a VNTR database to cover all provinces and proposed a set of optimized VNTR loci combinations for each province, in order to improve the preventive and control programs on tuberculosis, in China. Methods: A total of 15 loci VNTR was used to analyze 4 116 Mycobacterium tuberculosis strains, isolated from national survey of Drug Resistant Tuberculosis, in 2007. Hunter-Gaston Index (HGI) was also used to analyze the discriminatory power of each VNTR site. A set combination of 12-VNTR, 10-VNTR, 8-VNTR and 5-VNTR was respectively constructed for each province, based on 1) epidemic characteristics of M. tuberculosis lineages in China, with high discriminatory power and genetic stability. Results: Through the completed 15 loci VNTR patterns of 3 966 strains under 96.36% (3 966/4 116) coverage, we found seven high HGI loci (including QUB11b and MIRU26) as well as low stable loci (including QUB26, MIRU16, Mtub21 and QUB11b) in several areas. In all the 31 provinces, we found an optimization VNTR combination as 10-VNTR loci in Inner Mongolia, Chongqing and Heilongjiang, but with 8-VNTR combination shared in other provinces. Conclusions: It is necessary to not only use the VNTR database for tracing the source of infection and cluster of M. tuberculosis in the nation but also using the set of optimized VNTR combinations in monitoring those local epidemics and M. tuberculosis (genetics in local) population.

[Frequency and clinical relevance of rapidly growing mycobacterium isolated from respiratory samples]

OBJECTIVE

To assess the frequency and clinical relevance of rapidly growing mycobacterium (RGM) isolates in a tuberculosis referral center in Beijing, China.

METHODS

All isolates were identified by using targeted gene sequencing. RESULTS of species identification for 228 nontuberculous Mycobacterium (NTM) isolates from respiratory samples were analyzed, and available medical files of patients from whom NTM were isolated were reviewed retrospectively. Diagnostic criteria for RGM pulmonary disease issued by the American Thoracic Society (ATS) were used to determine clinical relevance.

RESULTS

Isolates of Mycobacterium abscessus (M.abscessus) and Mycobacterium fortuitum (M.fortuitum) accounted for 28.9% (66 isolates) and 8.8% (20 isolates)of NTM isolates, respectively. Sixty-six M. abscessus isolates from 32 patients had evaluable medical files, including 28 cases diagnosed as definite M. abscessus lung disease, and 4 as probable M. abscessus lung disease. Eight M. fortuitum isolates from 8 cases had evaluable medical files, and all of them were diagnosed as unlikely lung disease. Mycobacteria Growth Indicator Tube (MGIT) was more effective to diagnose M. abscessus lung disease, as compared with Lowestein-Jensen medium (23/24 vs 18/28).

CONCLUSIONS

RGM is a common NTM in our institute. M. abscessus is mostly associated with RGM lung disease, but M. fortuitum is not.

Retrotransposition of a yeast group II intron occurs by reverse splicing directly into ectopic DNA sites

Group II introns, the presumed ancestors of nuclear pre-mRNA introns, are site-specific retroelements. In addition to "homing" to unoccupied sites in intronless alleles, group II introns transpose at low frequency to ectopic sites that resemble the normal homing site. Two general mechanisms have been proposed for group II intron transposition, one involving reverse splicing of the intron RNA directly into an ectopic DNA site, and the other involving reverse splicing into a site in RNA followed by reverse transcription and integration of the resulting cDNA by homologous recombination. Here, by using an "inverted-site" strategy, we show that the yeast mtDNA group II intron aI1 retrotransposes by reverse splicing directly into an ectopic DNA site. This same mechanism could account for other previously described ectopic transposition events in fungi and bacteria and may have contributed to the dispersal of group II introns into different genes.

[Cluster analysis of Dendrobium by RAPD and design of specific primer for Dendrobium candidum]

OBJECTIVE

To analyze the genetic relationship of Dendrobium and design a specific primer to differentiate Dendrobium candidum effectively.

METHOD

Random amplified polymorphic DNA (RAPD) technique was used to analyze the genetic relationships of 26 species of Dendrobium and one species of Ephemerantha. Dendrogram was constructed by UPGMA. According to the sequence of DNA fragment selected, Sangon 18 primer had been extended from 3' extreme to 20 bp in order to form a specific primer.

RESULT AND CONCLUSION

This primer can be used to distinguish Dendrobium candidum from other Dendrobium effectively. Such a technique provides a new way for the identification of Chinese traditional medicines.

Purification and cloning of carp nephrosin, a secreted zinc endopeptidase of the astacin family

We have purified a secreted proteinase of 23 kDa from carp head kidney by sequential column chromatography on a Reactive Blue 72-agarose dye affinity column and an FPLC Mono-P column. The secretion of this proteinase from carp head kidney can be stimulated by high concentrations of potassium. Since the carp proteinase is present mainly in the head kidney, kidney, and spleen (all of which are lymphohematopoietic organs), it is named nephrosin. The carp nephrosin is most sensitive to metal chelators, but not to inhibitors specific for other classes of proteinases. A cDNA clone has been isolated from a carp head kidney cDNA library by immunoscreening with a polyclonal antiserum raised against purified nephrosin. The cloned cDNA is 1086 base pairs in length and has an open reading frame encoding a protein of 273 amino acids, including a 19-amino acid signal peptide and 56-amino acid propeptide. The deduced amino acid sequence shows moderate levels of identity to medaka HCE1 (52.5%), medaka LCE (50.7%), crayfish astacin (33.2%), murine meprin-alpha (34%), and murine meprin-beta (33.5%), all members of the astacin family of zinc endopeptidases. Nephrosin is the first member of the astacin family found in lymphohematopoietic tissues.

Internal jugular phlebectasia

Phlebectasia, defined as abnormal venous dilation, may occur in a number of different sites. Two cases with definite diagnosis of internal jugular phlebectasia were reported. The first case was a 6-year-old girl with a bulging mass on right neck for 3 years. Angiography and CT scan showed definite diagnosis, and the bulging mass was resected from the internal jugular vein (IJV). The second case was a 66-year-old female patient, also complained of a bulging mass on her right neck. Sonogram and CT scan also showed the same diagnosis. Because it did not bother the patient, she was just under close observation. From the three kinds of diagnostic modalities, we found sonography is an effective technique because of its clarity, safety and low cost.