[Public health risk and prevention and control of sporotrichosis]

Sporotrichosis, a fungal infection caused by Sporothrix species, can greatly lead to chronic inflammation of the skin, mucosa, and lymphatic vessels and disseminate systemically sometimes, even threatening life. It is known that Sporothrix is distributed worldwide, while in China, most of the cases were reported in northeast China and parts of south China. Sporothrix globosa is the main source of infection, and other regions may lack relevant awareness and attention to the disease, making it a public health challenge in China. Thus, it is important to understand its epidemiology and public health risks to prevent and control the disease properly.

[Antimicrobial resistance and genomic characterization of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces of China in 2020]

Objective: To understand the antimicrobial resistance and genome characteristics of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces in China in 2020. Methods: In 2020, 265 Campylobacter strains including 244 Campylobacter jejuni and 21 Campylobacter coli collected from retailed poultry meat samples in China were tested for antimicrobial resistance to 9 antimicrobial compounds by using the agar dilution method. Forty-two selected isolates were sent for whole genome sequencing and 38 high-quality genomes were analyzed for their antimicrobial resistance genes, virulence genes, sequence types and genetic diversity. Results: The resistance rates of Campylobacter isolates from poultry meats to tetracycline, nalidixic acid and ciprofloxacin were the highest (84%-100%), with 53.2% of the isolates showing multidrug resistance in this study. The resistance rates of C. coli to erythromycin, azithromycin, telithromycin, gentamicin and clindamycin were significantly higher than those of C. jejuni (P<0.05). The resistance genes conferring resistance to β-lactams (100%, 38/38), quinolones (94.7%, 36/38), tetracycline (81.6%, 31/38) and aminoglycosides (50%, 19/38) were the most frequently detected among 38 Campylobacter genomes. C. jejuni carried more virulence genes than C. coli. In total, 19 and 17 sequence types (ST) were obtained from 20 sequenced C. jejuni and 18 C. coli isolates, respectively, including 5 novel STs. The isolates showed a high genetic diversity based on their sequence types. Conclusion: The phenomenon of antimicrobial resistance in Campylobacter from poultry meat sources in China is relatively serious, and resistance and virulence genes are widely distributed in Campylobacter. There is genetic diversity in Campylobacter.

[Antimicrobial resistance and plasmid-mediated colistin resistance mechanism of diarrheagenic Escherichia coli recovered from foods in parts of China in 2020]

Objective: To investigate the antimicrobial resistance of food-borne diarrheagenic Escherichia coli (DEC) and the prevalence of mcr genes that mediates mobile colistin resistance in parts of China, 2020. Methods: For 91 DEC isolates recovered from food sources collected from Fujian province, Hebei province, Inner Mongolia Autonomous Region and Shanghai city in 2020, Vitek2 Compact biochemical identification and antimicrobial susceptibility testing platform was used for the detection of antimicrobial susceptibility testing (AST) against to 18 kinds of antimicrobial compounds belonging to 9 categories, and multi-polymerase chain reaction (mPCR) was used to detect the mcr-1-mcr-9 genes, then a further AST, whole genome sequencing (WGS) and bioinformatics analysis were platformed for these DEC isolates which were PCR positive for mcr genes. Results: Seventy in 91 isolates showed different antimicrobial resistance levels to the drugs tested with a resistance rate of 76.92%. The isolates showed the highest antimicrobial resistance rates to ampicillin (69.23%, 63/91) and trimethoprim-sulfamethoxazole (59.34%, 54/91), respectively. The multiple drug-resistant rate was 47.25% (43/91). Two mcr-1 gene and ESBL (extended-spectrum beta-lactamase) positive EAEC (enteroaggregative Escherichia coli) strains were detected. One of them was identified as serotype of O11:H6, which showed a resistance profile to 25 tested drugs referring to 10 classes, and 38 drug resistance genes were predicted by genome analysis. The other one was O16:H48 serotype, which was resistant to 21 tested drugs belonging to 7 classes and carried a new variant of mcr-1 gene (mcr-1.35). Conclusion: An overall high-level antimicrobial resistance was found among foodborne DEC isolates recovered from parts of China in 2020, and so was the MDR (multi-drug resistance) condition. MDR strains carrying multiple resistance genes such as mcr-1 gene were detected, and a new variant of mcr-1 gene was also found. It is necessary to continue with a dynamic monitoring on DEC contamination and an ongoing research into antimicrobial resistance mechanisms.

[Phenotypic and genomic characterization for Salmonella isolates recovered from meat products in Beijing wholesale markets, 2014-2015]

Objective: To analyze the phenotypic and genomic characteristics of Salmonella isolates recovered from meat products in Beijing wholesale markets. Methods: A total of 336 Salmonella strains from meat products collected from wholesale markets in Beijing were tested for antimicrobial resistance to 25 antimicrobial compounds by micro-broth dilution method; whole genome data were sequenced, followed by the serotype and ST type prediction by Seqsero2 and SISTR software, and the drug resistance genes and virulence factors were also predicted with CARD and VFDB databases of Abricate software; Salmonella serotyping assay kit and serum agglutination method were used for serotype confirmation of some isolates with different genome prediction results. Results: The resistance rates to Nalidixic acid and Ampicillin were 62.5% (210/336) and 55.1% (185/336), respectively, and all isolates were susceptible to Tigecyclin, Cefoxitin and Carbapenem antimicrobial compounds; 207 isolates (61.6%, 207/336) were multi-drug resistant, some could even be resistant to ten categories of drugs at the same time, and the most common antimicrobial resistance spectrum was NAL-AMP-SAM. A total of 24 serotypes were detected with predominant serotypes of Enteritidis (34.5%, 116/336), Derby (17.3%, 58/336) and Indiana (10.4%, 35/336). A total of 27 ST types were detected, the dominant type was ST11; ST types were in good consistency with serotypes; The detection rates of resistant genes referred to aminoglycosides, fluoroquinolones, β-lactams, sulfonamides and tetracyclines are more than 48%, and the first two reached 100%. The prediction of drug resistance genes was consistent with the results of antimicrobial resistance phenotype. A total of 122 virulence genes were predicted, 74 of which existing among all isolates. Conclusion: Salmonella in meat from the wholesale markets of Beijing has a high proportion of multiple drug resistance, a complex drug resistance spectrum, a variety of serotypes and ST types, and a high carrying rate of drug resistance gene and virulence gene; drug resistance phenotype and genotype are relatively consistent.

[Analysis on serotype and antimicrobial resistance of invasive non-typhoidal Salmonella]

Objective: To investigate the serotypes and antimicrobial resistance of seven invasive non-typhoidal Salmonella (iNTS) isolates. Methods: For 7 iNTS strains collected, serotype identification, antimicrobial susceptibility testing and whole genome sequencing were performed. We identified, annotated and analyzed the serotypes, MLST types, and antimicrobial resistance genes. Results: Among the 7 tested iNTS isolates, we found one Salmonella Typhimurium strain and two Salmonella Ⅰ 4, [5], 12: i:- strains whose MLST types were ST34, two Salmonella Enteritidis strains, one Salmonella Corvallis strain and one strain of unknown serotype with the antigenic formulae of Ⅰ 4, [5], 12: d:- (ST279 type). Six of seven strains were monophasic and the deletion or pseudogenization of Salmonella Flagellum gene might contribute to the enhancement of Salmonella invasiveness. None was found to be resistant to tigarcycline, aztreonam, amikacin, cephalosporins and carbapenem and one Salmonella Typhimurium strain was found to be co-resistant to eight classes of antimicrobials at the same time. Resistance genes were generally in accord with relative resistant phenotypes. Conclusion: The iNTS strains could show high level multi-drug resistance, indicating that close attention should be paid to the resistance of iNTS though the overall resistance might be relatively not high.

Research Progress and Forensic Identification of Alcoholic Cardiomyopathy

Abstract

With the rapid development of the social economy in China, the incidence of diseases caused by excessive drinking is gradually increasing as well. Alcoholic cardiomyopathy refers to long-term high intake of ethanol, and has typical dilated cardiomyopathy characteristics, such as, hemodynamic changes, symptoms, signs, and morphological features. It is a kind of cardiomyopathy that excludes other causes of dilated cardiomyopathy. Due to the lack of specific pathological changes, the forensic pathological identification of alcoholic cardiomyopathy can only be based on the patient's medical history and by ruling out other causes of cardiomyopathy. This paper reviews the pathogenesis and forensic identification of alcoholic cardiomyopathy in order to provide reference for forensic pathologists and clinicians.

[Interpretation for diagnosis of Yersiniosis]

Yersiniosis is one of the "other infectious diarrhea" of the notifiable infectious diseases and also an important food-borne disease. However, it lacked the basis or standard for diagnosis. The Chinese Preventive Medicine Association coordinated experienced researchers from National Institute for Communicable Disease Control and Prevention, China CDC and other institutes to produce the group standard entitled "Diagnosis of Yersiniosis" (T/CPMA 005-2019). Based on the principle of "legality, scientificity, advancement, and feasibility" , the standard gives a clear definition for Yerisiniosis, stipulates diagnosis basis, principles and main differential diagnosis and provides two informative appendixes for epidemiological and clinical characteristics and a normative appendix for laboratory detection. The standard provides accurate basis and methods of Yersiniosis diagnosis for hospitals and CDCs at all levels in China. It will solve the problems that Yersiniosis cannot be clearly diagnosed for clinical cases and in the outbreaks.

[Overview of resistance mechanisms in Campylobacter]

Campylobacter is a major cause of food-borne gastroenteritis worldwide. While mortality is low when people was infected with Campylobacter, morbidity imparted by post-infectious sequelae such as Guillain-Barré syndrome and irritable bowel syndrome is significantly noteworthy. Although fluoroquinolones and macrolides were the first line drug for the treatment of Campylobacter infections, there is a tough challenge in clinical treatment with high antimicrobial resistant rate and multi antimicrobial resistance arise. Based on the latest literature acquired in this work, we have chosen five classes of antibiotics always used in clinical, and discussed antibiotic resistance mechanisms and transmission of Campylobacter, in order to provide proper therapy both in the veterinary and human populations, and support basis data for the development of new drugs.

[Overview of Staphylococcus aureus mobile genetic elements and horizontal gene transfer of antimicrobial resistance genes]

The mechanism of antimicrobial resistance transmission mediated by mobile genetic elements (MGEs) in Staphylococcus aureus is highly complicated, leading a significant challenge for controlling the spread of the resistant Staphylococcus aureus strains. Based on the latest literature acquired in this work, we have overviewed the transmission mechanism of antimicrobial resistance encoding MGEs. It is notably that there are a number of MGEs, which may encode different antimicrobial resistance determinants and possess specific transmission mechanism. In spite of this specificity of the strains to their host (human or animal), some Staphylococcus aureus strains can be transmitted from animals to humans or vice versa. This ability of cross staphylococci transfer is an additional means to acquire new genetic material encoded by MGE. It was suggested in this review that study on transmission mechanism of MGEs mediated antimicrobial resistance genes could provide important biological information of their spreading and effectively help prevent and control of the resistant strains and/or resistance genes among human, animals and ecologies.

[Molecular typing characterization of food-borne methicillin-resistant Staphylococcus aureus in China]

Objective: To analyses the antimicrobial resistance and molecular characterization of 21 MRSA isolates cultured from retail foods from different provinces in China, and evaluate the molecular typing methods. Methods: Twenty-one MRSA isolates were obtained from national foodborne pathogen surveillance network in 2012 (Chinese salad, n=3; milk, n=1; cake, n=2; rice, n=1; cold noodle, n=1; spiced beef, n=1; dumpling, n=1; packed meal, n=1; salad, n=1; raw pork, n=9). The antimicrobial resistance of 21 strains to 12 antimicrobial agents was tested by broth dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to obtain the genetic types of MLST (ST) and spa typing. The clonal complex (CC) was assigned by eBURST soft and the MLVA type (MT) and MLVA complex (MC) were identified via the database of the MLVA website (http://www.mlva.net). SmaI pulsed-field gel electrophoresis (SmaⅠ-PFGE) was also carried out to obtain the PFGE patterns of 21 strains. The genetic diversity and discriminatory power of typing were calculated by the Simpson's index of diversity (diversity index, DI) to find out the best genotyping method for MRSA. Results: All MRSA isolates showed multi-drug resistance(MDR), and were resistant to oxacillin, benzylpenicillin, clindamycin and erythromycin, and 71.4% (15/21), 47.6% (10/21), 42.9% (9/21) and 28.6% (6/21) of the MRSA isolates were resistant to tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole and gentamicin, respectively. Moreover, one strain was found to be resistant to all three antimicrobials of levofloxacin, moxifloxacin and rifampicin. Great diversity was found in these food-associated MRSA (6 STs, 7 spa types, and 9 MTs). PFGE patterns were more diverse than those of other three molecular typing methods (19 pulse types). The index of diversity (DI) of PFGE, MLVA, spa typing and MLST was 0.99, 0.80, 0.73, and 0.61, respectively. Among the MRSA isolates, CC9-ST9-t899-MT929-MC2236 (PFGE Cluster Ⅴ) was the most prevalent clone, which were all cultured from raw pork (9 isolates). Besides, two MRSA were identified as CC59-ST338-t437-MT621-MC621 (PFGE Cluster Ⅳ). Different clone had their own resistance spectrum profiles. Conclusion: The food-borne MRSA isolates were all MDR in this study. Different clones had their own resistance spectrum profiles. MLVA represented a promising tool for molecular epidemiology tracing of MRSA in foodborne disease events.

[Antimicrobial susceptibility and drug-resistance genes of Yersinia spp. of retailed poultry in 4 provinces of China]

Objective: To monitor the antimicrobial resistance and drug-resistance genes of Yersinia enterocolitis, Y. intermedia and Y. frederiksenii recovered from retailed fresh poultry of 4 provinces of China. Methods: The susceptibility of 25 isolated Yersinia spp. to 14 classes and 25 kinds of antibiotics was determined by broth microdilution method according to CLSI (Clinical and Laboratory Standards Institute). The antibiotic resistance genes were predicted with antibiotic resistance genes database (ARDB) using whole genome sequences of Yersinia spp. Results: In all 22 Y. enterocolitis tested, 63.7% (14 isolates), 22.8% (5 isolates), 4.6% and 4.6% of 1 isolates exhibited the resistance to cefoxitin, ampicillin-sulbactam, nitrofurantoin and trimethoprim-sulfamethoxazole, respectively. All the 25 isolates were multi-drug resistant to more than 3 antibiotics, while 64.0% of isolates were resistant to more than 4 antibiotics. A few Y. enterocolitis isolates of this study were intermediate to ceftriaxone and ciprofloxacin. Most Yersinia spp. isolates contained antibiotic resistance genes mdtG, ksgA, bacA, blaA, rosAB and acrB, and 5 isolates recovered from fresh chicken also contained dfrA1, catB2 and ant3ia. Conclusion: The multi-drug resistant Yersinia spp. isolated from retailed fresh poultry is very serious in the 4 provinces of China, and their contained many kinds of drug-resistance genes.

[Serotype distribution and antimicrobial resistance of Salmonella isolates from retail chicken carcasses in six provinces of China]

Objective: To obtain the serotype diversity and antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses for sale in six regions of China. Methods: From August 2010 to March 2012, each month 20 retail chicken carcasses including freshly slaughtered, chilled and frozen samples were collected from supermarkets and farmer's markets in 7 monitoring sites in Beijing, Jilin province, Inner Mongolia Autonomous, Shanxi province, Jiangsu province and Guangdong province, respectively. Samples were routinely collected for 12 months for each site. 1 680 chicken carcasses were collected in total and 2 629 Salmonella strains were isolated by PCR and biochemical method. Luminex xMAP method and classical slide agglutination method were carried out to determine isolates' serotypes. Minimal inhibitory concentrations (MICs) of 10 classes of antimicrobials including 14 agents were determined using broth micro-dilution method. Mocular methods were used to determine antimicrobial resistance genes of CIP-CTX-CT co-resistant isolates. Results: In all, 2 629 Salmonella isolates, there were 17 seorgroups and 58 serotypes, B and D1 were the dominant serogroups with rates of 34.7% (n=913) and 31.0% (n=815), Enteritidis (30.8%, n=810), Indiana (17.6%, n=463), Infantis (10.6%, n=278) were the top three serovars. We found 224 CIP-CTX co-resistant S. Indiana containing 3 colistin resistant strains, one of them carrying mcr-1 gene and being ESBLs positive, which demonstrated a nine multi drug resistance against 11 antimicrobials tested. Conclusion: These data began to describe the complicated serovar diversity and heavy antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses in six regions of China. The findings highlight the emergence of ciprofloxacin and cefotaxime co-resistant S. Indiana and also a mcr-1 positive S. Indiana with heavy multi drug resistance.

[Laboratory-based characterization and traceability of an outbreak of necrotising enterocolitis]

Objective: Laboratory-based characterization and traceability were performed on an outbreak of necrotising enterocolitis (NEC) happened in a maternal and child health care hospital in China. Methods: Thirty-seven samples were collected from 3 NEC cases, that the clinical manifestations was bloody stools. Clostridium spp. isolation and identification were carried out on stool, breast milk, milk-based infant powder and environmental swab samples collected during NEC outbreak from October to November in 2016. Meanwhile, twenty-four swabs samples from ward environmental, staffs' hand as well as articles for neonates daily use were also collected and tested for Clostridium spp. after disinfection following outbreak. Pulsed-field gel electrophoresis (PFGE) analysis was performed on all Clostridium strains obtained. Results: 46% (17/37) samples were positive for a presumptive Clostridium spp. during the outbreak of NEC. One type of Clostridium spp. isolates was cultured from 10 samples including the hands of medical staffs, some medical equipments in the ward and milk-based infant powder ingested by the case, it was identified as C.butyricum. Another type of Clostridium spp. isolates was cultured from 2 samples including breast milk and inner wall of breast milk fresh-keeping bag, it was identified as C.sporogens. Both of these two types isolates were cultured from 5 samples including inner wall of breast milk box, inner wall of refrigerator, the handle of case's incubator and the case's stool. PFGE analysis showed that all 15 strains of C. butyricum and 7 strains of C.sporogens isolated from the samples mentioned above produced indistinguishable pulsotypes respectively. No NEC cases were found after disinfection following the outbreak and all samples collected after outbreak were negative for Clostridium spp. Conclusion: The outbreak of NEC was highly related to C. butyricum contamination within the hospital.

[Effect of nicotinic acetylcholine receptor α7 subunit gene on liver inflammatory reaction in mice with nonalcoholic steatohepatitis and related mechanisms]

Objective: To investigate the effect of nicotinic acetylcholine receptor α7 (α7nAChR) subunit gene on liver inflammation in mice with nonalcoholic steatohepatitis (NASH) and related mechanisms. Methods: C57BL/6J mice and α7nAChR gene knockout mice were fed for 24 weeks to establish the NASH model, and the mice were sacrificed to isolate and culture the primary liver macrophages. After the treatment with nicotine and endotoxin, ELISA was used to measure the levels of the inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in supernatant; indirect immunofluorescence assay and Western blot were used to observe the effect on the NF-κB signaling pathway, and quantitative PCR was used to measure the mRNA expression of Toll-like receptor-4 (TLR-4) in macrophages. An analysis of variance was used for comparison of means between multiple groups. Results: The results of ELISA showed that compared with the endotoxin+nicotine group of C57 NASH mice, the endotoxin+nicotine group of gene knockout NASH mice had significantly higher levels of IL-6 and TNF-α in supernatant (IL-6: 1 599±65 pg/ml vs 1 465±45 pg/ml, P < 0.05; TNF-α: 1 567±66 pg/ml vs 1 433±50 pg/ml, P < 0.05). The results of Western blot showed that compared with the endotoxin+nicotine group of C57 NASH mice, the endotoxin+nicotine group of gene knockout NASH mice had significantly higher relative protein expression of phosphorylated NF-κB and TLR-4 (NF-κB: 69 425±600 vs 51 133±200, P < 0.05; TLR-4: 93 387±684 vs 64 198±630, P < 0.05). The results of indirect immunofluorescence assay showed that the endotoxin+nicotine group of gene knockout NASH mice had a significantly higher fluorescence intensity of NF-κB than the endotoxin+nicotine group of C57 NASH mice. The results of PCR showed that the endotoxin+nicotine group of gene knockout NASH mice had significantly higher relative mRNA expression of TLR-4 than the endotoxin+nicotine group of C57 NASH mice (4.13±0.13 vs 2.93±0.14, P < 0.05). Conclusion: The α7nAChR gene knockout can aggravate the degree of inflammatory reaction in NASH, and its mechanism may be related to the fact that the NF-κB signaling pathway cannot be inhibited, which aggravates inflammatory reaction.

[Molecular characterization genetic diversity of extended-spectrum β-lactamases-harboring conjugative plasmids identified in multi-drug resistant Escherichia coli isolated from food in China]

Objective: The purpose of this study was to investigate the molecular characteristics of ESBL-encoding conjugative plasmid identified in muti-drug resistant Escherichia coli isolated from food. Methods: 465 Escherichia coli isolates were collected from national foodborne disease surveillance net from 2013 to 2014 (salad, n=159; meat, n=102; processed meat, n=95; cakes/rice, n=46; cooked dish, n=63). ESBLs strain was detected by Mueller-Hinton agar plate, and then its drug resistance was tested by agar dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to identify the corresponding ESBL genes. Plasmids were typed by PCR-based replicon typing and their characteristics were determined by S1-nuclease pulsed-field gel electrophoresis method. Broth mating assays were carried out for all isolates to determine whether the ESBL marker could be transferred by conjugation. Results: 12 E. coli were found to be resistant to cefotaxime, and all of which were confirmed as ESBLs. The 12 isolates all carried different types of CTX-M genes resistant to drug, and 7 of which carried TEM type as well. All 12 isolates contained at least one plasmid and some had four plasmids, with size ranging from 47-to 220-kb by S1-PFGE anaylsis. Seven isolates demonstrated the ability to transfer their cefotaxime resistance marker to the recotper strain J53 by only one plasmid. Conclusion: This study highlights the diversity of the multi-drug resistant E. coli and also the diversity of ESBL genes in China. Plasmids carrying these genes poses a serious threat to food safety in China.

[Nicotine alleviates the liver inflammation of non-alcoholic steatohepatitis induced by high-fat and high-fructose in mice]

OBJECTIVE

To investigate the anti-inflammation effects by activation of the cholinergic anti-inflammatory pathway and its mechanisms in non-alcoholic steatohepatitis (NASH) model mice.

METHODS

6-week-old male C57BL/6J (B6) mice were randomly divided into four groups: the first group was normal mice, injected with saline; the second group was normal mice, injected with nicotine; the third group was NASH model mice, injected with saline; the fourth group was NASH model mice, injected with nicotine. The experimental mice were fed with either standard chow (SC) or high-fat and high-fructose (HFHF) for 17 weeks to generate an NASH model mice. The mice received injection once daily for 3 weeks [nicotine dose, 400 μg/kg]. Then, their pathological characteristics and function of the liver were assessed. The expressions of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum were analyzed by enzyme linked immunosorbent assay (ELISA). The expressions of alpha 7 nicotinic acetylcholine receptors (α7nAChR), Toll-like receptors-4 (TLR-4) and nuclear factor κB of phosphory-lation (p-NF-κB) in Kupffer cells were determined by Western blot and immunofluorescence assays.

RESULTS

We successfully generated NASH model mice by imitating the high-fat and high-fructose dietary style of NASH patients. The results of our investigation demonstrated that nicotine could reduce significantly the levels of IL-6, and TNF-α in serum (P<0.05). The expression of p-NF-κB protein in the group which was NASH model mice injected with nicotine declined significantly as compared with the group which was NASH model mice injected with saline (P<0.05). And the expression of α7nAChR protein elevated significantly conversely (P<0.05).

CONCLUSION

Activation of the cholinergic anti-inflammatory pathway could inhibit the release of inflammatory factors as TNF-α and IL-6 in NASH model mice, and the mechanism for the inhibition of inflammatory was mediated by NF-κB pathway.

[Survey on fungi contamination and natural occurrence of mycotoxins in 94 corn feed ingredients collected from China]

Objective: To investigate fungi contamination and the natural occurrence of mycotoxins in corn feed ingredients collected from China. Methods: A total of 94 corn feed ingredient samples were collected from 8 Chinese provinces(i.e., Anhui, Hebei, Heilongjiang, Jilin, Jiangsu, Liaoning, Inner Mongolia, and Shandong)in February 2014. A tandem ultra-performance liquid chromatographymass spectrometry method was used for simultaneous detection of twelve kinds of mycotoxins, including aflatoxin(AF), type A and type B tricothecenes, and zearalenone(ZEN). Contaminated fungi were also identified and counted. Results: AF was detected in 36.2%(34/94)of samples; the concentration of AFB₁ was the highest in the four AFs with the range: 0.3~181.3 μg/kg; and then followed by AFB₂(range: 1.0-74.3 μg/kg). There were 7 samples(7.5%)with AFB₁ concentrations higher than the tolerance limit of 50 μg/kg. The concentration of type A tricothecenes in all samples was lower(0.1-10.5 μg/kg). DON had the most serious contamination than other kind of type B tricothecenes(range: 0.7-606.6 μg/kg; median: 66.3 μg/kg). The DON concentration in all samples was below the tolerance limit of 1 000 μg/kg. ZEN was detected in 76.6%(72/ 94)of samples(median: 36.9 μg/kg), with 3 samples having ZEN concentrations higher than the tolerance limit of 500 μg/kg. The survey on fungi contamination showed that all samples were contaminated by fungi(range: 5.0-1.4×10⁵ CFU/g). There were 18 and 3 samples with quantities of fungi higher than the tolerance and forbidden limits, respectively. The Aspergillus, Penicillium, Fusarium, Trichoderma and Mucor genuses were the predominant fungi in corn feed ingredients, with detection rates of 71.3%(67), 60.6%(57), 71.3%(67), 27.7%(26), and 24.5%(23), respectively. The detection rate of Fusarium moniliforme, 73.4%(69/94)was higher than that of Aspergillus flavus, 41.5%(39/94). Conclusion: In this survey, the corn feed ingredients were not seriously contaminated by AF and type A tricothecenes but mainly contaminated by type B trichothecenes, including DON and its derivatives, as well as ZEN. They were also contaminated by fungi such as Aspergillus, Penicillium, and Fusarium.

A KRT1 gene mutation related to epidermolytic ichthyosis in a Chinese family

We report a Chinese family with members affected by epidermolytic ichthyosis (EI), caused by KRT gene mutations. The proband was a 14-year-old boy who had simultaneous appearance of nephroblastoma and epidermolytic ichthyosis (EI). Both the patient and his mother exhibited the specific clinical and pathological manifestations of EI. We analysed all exons and flanking sequences of the KRT1 and KRT10 genes using PCR, and found that the proband and his mother had a G>C transition at nucleotide position 1432 in exon 7 of KRT1, resulting in an amino acid substitution of glutamate (GAA) to glutamine (CAA) at codon 478 (E478Q). The KRT10 gene had no mutations.

Differential microRNA expression in signet-ring cell carcinoma compared with tubular adenocarcinoma of human gastric cancer

Gastric cancer is a disease with a heterogeneous pathology; its pathological mechanisms remain unclear because there is a poor understanding of its etiology. In this study, we identified differentially expressed microRNAs (miRNAs) among various gastric cancer subtypes. miRNA microarray analysis and bioinformatic analysis were used to compare miRNA expression between the signet-ring cell carcinoma and tubular adenocarcinoma subtypes of gastric cancer. Thirteen dysregulated miRNAs were identified in signet-ring cell carcinoma compared with tubular adenocarcinoma: miR-30a, miR-26b, miR-381, let-7i, miR-29c, miR-543, miR-499-3p, miR-628-3p, miR-524-5p, miR-181b, miR-1914, miR-663b, and miR-676. This is the first time that miR-499-3p, miR-628-3p, miR-524-5p, and miR-1914 have been identified in gastric cancer tissues. Bioinformatic analysis using target prediction algorithms indicated that these miRNAs are directly involved in gastric cancer pathogenesis and have different pathological mechanisms in various subtypes of signet-ring cell carcinoma and tubular adenocarcinoma. The miRNA expression patterns in different gastric adenocarcinoma subtypes may help discriminate between signet-ring cell and tubular gland cancer or other gastric cancer subtypes that would otherwise be difficult to identify using routine histological and immunohistochemical analyses. These preliminary data should be verified in further prospective studies.

Isolation, molecular cloning, and characterization of a novel porcine lymphotoxin beta receptor gene

The lymphotoxin beta receptor (LTβR) is a member of the tumor necrosis factor family of receptors (TNFR). It plays a role in regulating lymphoid organogenesis and homeostasis of the immune system. In the present study, the full coding region of a putative LTβR gene of Sus scrofa was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and cloned for the first time (accession Nos. JX457347 and AFU74012). In addition, analysis of the tissue expression profile was carried out via RT-PCR. The full-length coding region of porcine LTβR had 1266 nucleotides (molecular weight, 45.61 kDa; pI, 5.71) and encoded 421 amino acids. Bioinformatic prediction indicates that LTβR belongs to the TNFR superfamily and contains a TNFR domain. The sequence homology analysis revealed that the amino acid sequences of S. scrofa LTβR had 82.9, 82.4, 81.3, 80.5, 78.7, 74.6, and 73.0% identity with those of Equus caballus, Canis lupus, Ailuropoda melanoleuca, Oryctolagus cuniculus, Bos taurus, Mus musculus, and Homo sapiens, respectively. The phylogenetic tree based on the amino acid sequences of LTβR from 8 species revealed that S. scrofa was more closely related to E. caballus, C. lupus, and A. melanoleuca. RT-PCR analysis showed that the porcine LTβR gene was differentially expressed (e.g., high, moderate, low, or nonexistent) in various tissues (e.g., prostate, pituitary, brainstem, and esophagus, respectively). This may be related to differences in the regulation of LTβR in the different tissues.

Identification of two ATR-dependent phosphorylation sites on coronavirus nucleocapsid protein with nonessential functions in viral replication and infectivity in cultured cells

Coronavirus encodes an extensively phosphorylated and highly basic nucleocapsid (N) protein. Previous studies have identified Ser190, Ser192, Thr378 and Ser379 as the phosphorylation sites for coronavirus infectious bronchitis virus (IBV) N protein. In this study, we show that phosphorylation at Thr378 and Ser379 sites is dependent on the ataxia-telangiectasia mutated (ATM) and Rad3-related (ATR), a kinase activated during IBV replication. Introduction of Ala substitutions at these two sites individually, in combination of the two and together with other two sites (Ser190 and Ser192) into an infectious IBV clone did not affect recovery of the recombinant viruses containing the mutations. A mutant virus (rIBV-Nm4) carrying the four Ala substitutions grew at a similar, if not better, growth rate as wild type virus. This study reveals a cellular kinase responsible for phosphorylation of a coronavirus N protein at two positions and the functional consequence of this modification on coronavirus replication.

•

We study the functional relevance of phosphorylation of IBV N on viral replication.

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We identify two ATR-dependent phosphorylation sites on IBV N protein.

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We analyze the functions of these sites on IBV replication and infectivity.

APOE-mimetic peptides reduce behavioral deficits, plaques and tangles in Alzheimer's disease transgenics

BACKGROUND

After age, the second largest risk factor for Alzheimer's disease (AD) is apolipoprotein E (APOE) genotype, where APOE4 is associated with lower apoE protein levels, more severer brain pathology, enhanced inflammation and disease. Small peptides corresponding to the receptor-binding region of apoE mimic the anti-inflammatory activity of the apoE holoprotein. These apoE mimetics greatly improve behavioral outcomes and neuronal survival in head trauma models that display AD pathology and neuronal loss.

OBJECTIVE

To determine whether apoE mimetics change behavior, inflammation and pathology in CVND-AD (SwDI-APP/NOS2(-/-)) transgenic mice.

METHODS

Starting at 9 months, apoE peptides were subcutaneously administered 3 times per week for 3 months followed by behavioral, histochemical and biochemical testing.

RESULTS

Treatment with apoE mimetics significantly improved behavior while decreasing the inflammatory cytokine IL-6, neurofibrillary tangle-like and amyloid plaque-like structures. Biochemical measures matched the visible pathological results.

CONCLUSIONS

Treatment with apoE mimetics significantly improved behavior, reduced inflammation and reduced pathology in CVND-AD mice. These improvements are associated with apoE-mimetic-mediated increases in protein phosphatase 2A activity. Testing in additional AD models showed similar benefits, reinforcing this novel mechanism of action of apoE mimetics. These data suggest that the combination of anti-inflammatory and neuroprotective activities of apoE mimetics represents a new generation of potential therapeutics for AD.

Sumoylation of the nucleocapsid protein of severe acute respiratory syndrome coronavirus

Severe acute respiratory syndrome coronavirus (SARS‐CoV) encodes a highly basic nucleocapsid (N) protein of 422 amino acids. Similar to other coronavirus N proteins, SARS‐CoV N protein is predicted to be phosphorylated and may contain nuclear localization signals, serine/arginine‐rich motif, RNA binding domain and regions responsible for self‐association and homo‐oligomerization. In this study, we demonstrate that the protein is posttranslationally modified by covalent attachment to the small ubiquitin‐like modifier. The major sumoylation site was mapped to the ⁶²lysine residue of the N protein. Further expression and characterization of wild type N protein and K62A mutant reveal that sumoylation of the N protein drastically promotes its homo‐oligomerization, and plays certain roles in the N protein‐mediated interference of host cell division. This is the first report showing that a coronavirus N protein undergoes posttranslational modification by sumoylation, and the functional implication of this modification in the formation of coronavirus ribouncleoprotein complex, virion assembly and virus–host interactions.

Ciprofloxacin-loaded bovine serum albumin microspheres: preparation and drug-release in vitro

Ciprofloxacin albumin microspheres were prepared by the spray drying technique, with bovine serum albumin as the natural biodegradable wall material. The spherical microspheres, flowed well, were organic solvent free and in the size range 1-5 microm. The drug release from the microspheres could be retarded by further thermal denaturation. The sustained-release microspheres were suitable for dry powder inhaled lung drug delivery systems.

Aflatoxins and fumonisins in corn from the high-incidence area for human hepatocellular carcinoma in Guangxi, China

A comparative study on the natural occurrence of aflatoxins and Fusarium toxins was conducted with corn samples from high- and low-incidence areas for human primary hepatocellular carcinoma (PHC) in Guangxi, China. In samples from the high-risk area, aflatoxin B(1) was the predominant toxin detected in terms of quantity and frequency, with its concentration ranging between 9 and 2496 microg/kg and an 85% incidence of contamination. Among the samples, 13 (76%) exceeded the Chinese regulation of 20 microg/kg for aflatoxin B(1) in corn and corn-based products intended for human consumption. Significant differences in aflatoxin B(1), B(2), and G(1) and total aflatoxin concentrations in corn between the areas were found (P < 0.05). The average daily intake of aflatoxin B(1) from corn in the high-risk area was 184.1 microg, and the probable daily intake is estimated to be 3.68 microg/kg of body weight/day, 3.20 times the TD(50) in rats. Corn samples from both areas were simultaneously contaminated with fumonisins B(1), B(2), and B(3). Aflatoxin B(1) may play an important role in the development of PHC in Guangxi.

Characterization of mutant neutrophil elastase in severe congenital neutropenia

Severe congenital neutropenia is a heritable human disorder characterized by neutropenia and acute myelogenous leukemia. We recently determined that the majority of cases result from de novo or autosomal dominantly inherited heterozygous mutations in ELA2, encoding neutrophil elastase. Neutrophil elastase is a chymotryptic serine protease localized in granules of neutrophils and monocytes and is the major target of inhibition of the serpin alpha(1)-antitrypsin. The mutations causing severe congenital neutropenia consist of amino acid missense substitutions, in-frame deletion, splice donor mutation producing a deletion, splice acceptor mutation causing insertion of novel residues, and protein truncating mutations of the carboxyl terminus resulting from nonsense substitutions and deletions leading to frameshifts. We have expressed 14 mutant forms of neutrophil elastase in vitro and have characterized their biochemical properties. The mutations have variable effects on proteolytic activity, eliminating the possibility that the disease results from haploinsufficiency. There is no evidence that the mutant enzymes are cytotoxic. The mutant enzymes retain vulnerability to inhibition by alpha(1)-antitrypsin, but demonstrate variable avidity for interaction with this serpin. Somewhat surprisingly, the mutant enzymes inhibit the wild type enzyme when both are coexpressed within the same cell, suggesting the potential to interfere with normal subcellular trafficking or post-translational processing.

Production of alternaria mycotoxins by Alternaria alternata isolated from weather-damaged wheat

The production of Alternaria mycotoxins by Alternaria alternata isolated from Chinese weathered wheat kernels were first investigated on polished rice and durum wheat grains. These mycotoxins included alternariol (AOH) and its monomethyl ether (AME), altenuene (ALT), altertoxin I (ATX-I), and tenuazonic acid (TA). Of 25 isolates tested, all were AOH and AME producers, 21 (84%) coproduced ALT and ATX-I, and 8 (32%) produced TA in rice culture. TA was the most abundant toxin produced at a level ranging from 1,369 to 3,563 mg/kg. Much smaller amounts of AOH, AME, ALT, and ATX-I were present with average concentrations of 54, 40, 44, and 8 mg/kg, respectively. There were linear correlations between the level of AOH and AME (r = 0.846), alternariols (AOH plus AME) and ALT (r = 0.785), and ATX-I and TA (r = 0.553). Polished rice medium seems to support a bit more production of Alternaria metabolites than wheat but with an insignificant difference in concentrations (P > 0.05). A study of the time-course of toxin production by A. alternata isolates indicated that AOH production began faster than any other toxins monitored, and ALT production exhibited a progressive increase throughout the experiment. TA producers might reveal their considerably higher ability to produce toxin in the field despite their low frequency.

[Tetrandrine loaded sustained-release microcapsules for lung targeting]

AIM

To prepare lung targeted tetrandrine (TET) loaded sustained-release drug delivery system by microencapsulation, decrease the toxicity and enhance the therapeutic function of anti-pulmonary hypertension of TET.

METHODS

Albumin microcapsules were produced by spray drying-thermal denaturation, a new technique. Some characterization of the prepared microcapsules was evaluated. Distribution of the microcapsules and their anti-pulmonary hypertension effect in vivo were investigated.

RESULTS

The spherical microcapsules showed a drug loading of 37.88%. Compared to the original drug, the rate of TET released from the positively charged microcapsules in vitro was significantly decreased and fitted well by Higuchi equation. The TET concentrations in mouse lungs of TET microcapsules were significantly higher than those of TET injection, and the mean retained time of TET in lungs was prolonged from 157.1 h to 223.6 h after microencapsulation. The in vitro--in vivo correlation was established and confirmed (P < 0.001).

CONCLUSION

The new spray drying-thermal denaturation method allows the preparation of drug loaded albumin microcapsules with desired results. The prepared microcapsules were found to have the potential function of delivering TET to pulmonary artery via i.v., with low toxicity and high efficacy.

[Study on the relationship of metallothionein and antioxidases in protective mechanism of cardiomyocytes]

AIM

To study the relationship of Metallothionein (MT) and antioxidases in hypoxia/reoxygenation (H/R) and hypoxic preconditioning (HPC).

METHODS

H/R and HPC model of rat cultured cardiomyocytes were established. Then the contents of MT and relevant changes of activities of antioxidases (SOD, CAT, GSHpx) of cardiomyocytes were determined while pretreated with the treatment: HPC. Zn2+ inducing MT or MT antibody.

RESULTS

In HPC and Zn2+ induced groups, all the contents of MT and the activities of antioxidases were obviously higher than those in H/R (P < 0.05, P < 0.01 respectively). While using MT, the activities of SOD were progressively increased than control (P < 0.05), CAT and GSHpx activities were lower than control (P < 0.01), but were significantly higher than those in I/R group (P < 0.01). In MT antibody groups, the activities of antioxidase were decreased extremely.

CONCLUSION

MT has effects on the cardiomyocytes protective role of HPC. And can afford more capacity for cardiomyocytes to tolerate the H/R damage by the mechanism of increasing the activities of antioxidase.

Selection of a dominant negative retinoblastoma protein (RB) inhibiting satellite myoblast differentiation implies an indirect interaction between MyoD and RB

Satellite myoblasts serve as stem cells in postnatal skeletal muscle, but the genes responsible for choosing between growth versus differentiation are largely undefined. We have used a novel genetic approach to identify genes encoding proteins whose dominant negative inhibition is capable of interrupting the in vitro differentiation of C2C12 murine satellite myoblasts. The screen is based on fusion of a library of cDNA fragments with the lysosomal protease cathepsin B (CB), such that the fusion protein intracellularly diverts interacting factors to the lysosome. Among other gene fragments selected in this screen, including those of known and novel sequence, is the retinoblastoma protein (RB) pocket domain. This unique dominant negative form of RB allows us to genetically determine if MyoD and RB associate in vivo. The dominant negative CB-RB fusion produces a cellular phenotype indistinguishable from recessive loss of function RB mutations. The fact that the dominant negative RB inhibits myogenic differentiation in the presence of nonlimiting concentrations of either RB or MyoD suggests that these two proteins do not directly interact. We further show that the dominant negative RB inhibits E2F1 but cannot inhibit a forced E2F1-RB dimer. Therefore, E2F1 is a potential mediator of the dominant negative inhibition of MyoD by CB-RB during satellite cell differentiation. We propose this approach to be generally suited to the investigation of gene function, even when little is known about the pathway being studied.

Mycotoxins (trichothecenes, zearalenone and fumonisins) in cereals associated with human red-mold intoxications stored since 1989 and 1991 in China

Two corn powder samples implicated in the human food poisoning that occurred in Guangxi province in 1989, and eight wheat and two barley samples linked to an episode that involved about 130,000 people in gastrointestinal disorders in Anhui province in 1991 were analyzed for trichothecenes including deoxynivalenol (DON), nivalenol (NIV) and their esters, zearalenone (ZEA) and fumonisins (FMs) by gas chromatography/mass spectroscopy and high performance liquid chromatography, and T-2 toxin by enzyme-linked immunosorbent assays. DON was detected in all samples as a major trichothecene (16-51,450 microg kg(-1)), and NIV was in one corn, one barley and all wheat at relatively low levels (10-6935 microg kg(-1)). ZEA was found in all corn and barley, and six wheat samples (46-3079 microg kg(-1)). In addition, 3-acetyl-DON (2544 microg kg(-1)) and 15-acetyl-DON (2537 microg kg(-1)) were detected separately in one corn and one wheat sample. The highest levels of these mycotoxins were found in one wheat sample associated with the human intoxication in Anhui province. FMs in corn were below 1000 microg kg(-1). Risks of DON and ZEA on the people who consumed the causative cereals were assessed.

Genetic analysis of N-acetyltransferase polymorphism in a Chinese population

AIM

To study the genetic basis of N-acetylatransferase polymorphism in Chinese.

METHODS

Genotypes in 120 healthy Han volunteers from 19 provinces of China were assayed. The 3 common mutant alleles (M1, M2, M3) and one normal wild-type (WT) allele of the N-acetyltransferase (NAT2) gene were detected by allele-specific polymerase chain reaction technique.

RESULTS

The NAT2 allele frequencies in 120 Chinese (WT = 0.625, M1 = 0.0458, M2 = 0.188, M3 = 0.142) were different (P < 0.01). The NAT2 genotype distribution for all detected combinations of NAT2 alleles in 120 Chinese subjects was consisitent with Hardy-Weinberg equilibrium (chi 2 = 7.27, nu = 8, 0.7 > P > 0.5). Fifty subjects (41.7%) were homozygous wildtypes, 50 subjects (41.7%) were heterozygous mutants, and 20 subjects (16.7%) were homozygous mutants.

CONCLUSION

The lower frequency of mutant M1 allele compared with that of Caucasians explains the low frequency of slow acylators in Chinese.

Negative correlation between cyclophilin mRNA level in leukocytes of renal allograft recipients and ciclosporin concentration in whole blood

AIM

To study mRNA level of cyclophilin in the white blood cells (WBC) of the renal allograft recipients (RAR) and its correlation with ciclosporin concentration in whole blood.

METHODS

The cyclophilin mRNA levels and beta-actin as controls in the WBC of 47 RAR were measured by quantitative reverse transcription polymerase chain reaction. The blood ciclosporin assay utilized monoclonal antibody fluorescence polarization immunoassay.

RESULTS

With the increase of ciclosporin concentration in whole blood (from 62 micrograms.L-1 to 678 micrograms.L-1), relative cyclophilin mRNA level in the WBC of RAR decreased nonlinearly (from 1.1 to 0.03, r = 0.8195).

CONCLUSION

There was a negative correlation between the mRNA level of cyclophilin in the WBC of RAR and the ciclosporin concentration in whole blood.

On the mechanism of DNA transfection: efficient gene transfer without viruses

From an investigation of how transfected DNA navigates from the cell surface to the nucleus, we have developed a transfection method for primary human fibroblasts that approaches the efficiency of viruses. We have visually tracked the subcellular routing of exogenous DNA and find that all cells in an asynchronous population are surprisingly competent in the nuclear uptake of DNA, but two steps practically limit efficient transfection to a minority of cells. First, regardless of the method used to traverse the cell membrane--CaPO4 precipitation, lipofection or electroporation--it appears that nuclear transport of DNA requires routing through endosomes and lysosomes. Apparent abrogation of endosome-lysosome fusion or translocation with microfilament or microtubule toxins, respectively, inhibits the nuclear accumulation of transfected DNA, but interruption of lysosomal function with protease inhibitors promotes it. Second, in normal human fibroblasts, which are refractory to transfection the exogenous DNA is rapidly excluded from the nucleus, but in HeLa cells, which are readily transfected, there is prolonged nuclear stability of the DNA, indicating the failure in HeLa cells of a mechanism for the elimination of foreign DNA. These observations imply strategies for optimizing gene transfer efficiency in virus-independent approaches to gene therapy.

Genetic heterogeneity in familial acute myelogenous leukemia: evidence for a second locus at chromosome 16q21-23.2

The identification of genes responsible for the rare cases of familial leukemia may afford insight into the mechanism underlying the more common sporadic occurrences. Here we test a single family with 11 relevant meioses transmitting autosomal dominant acute myelogenous leukemia (AML) and myelodysplasia for linkage to three potential candidate loci. In a different family with inherited AML, linkage to chromosome 21q22.1-22.2 was recently reported; we exclude linkage to 21q22.1-22.2, demonstrating that familial AML is a heterogeneous disease. After reviewing familial leukemia and observing anticipation in the form of a declining age of onset with each generation, we had proposed 9p21-22 and 16q22 as additional candidate loci. Whereas linkage to 9p21-22 can be excluded, the finding of a maximum two-point LOD score of 2.82 with the microsatellite marker D16S522 at a recombination fraction theta = 0 provides evidence supporting linkage to 16q22. Haplotype analysis reveals a 23.5-cM (17.9-Mb) commonly inherited region among all affected family members extending from D16S451 to D16S289. In order to extract maximum linkage information with missing individuals, incomplete informativeness with individual markers in this interval, and possible deviance from strict autosomal dominant inheritance, we performed nonparametric linkage analysis (NPL) and found a maximum NPL statistic corresponding to a P-value of .00098, close to the maximum conditional probability of linkage expected for a pedigree with this structure. Mutational analysis in this region specifically excludes expansion of the AT-rich minisatellite repeat FRA16B fragile site and the CAG trinucleotide repeat in the E2F-4 transcription factor. The "repeat expansion detection" method, capable of detecting dynamic mutation associated with anticipation, more generally excludes large CAG repeat expansion as a cause of leukemia in this family.

Multiprotein bridging factor 1 (MBF1) is an evolutionarily conserved transcriptional coactivator that connects a regulatory factor and TATA element-binding protein

Multiprotein bridging factor 1 (MBF1) is a transcriptional cofactor that bridges between the TATA box-binding protein (TBP) and the Drosophila melanogaster nuclear hormone receptor FTZ-F1 or its silkworm counterpart BmFTZ-F1. A cDNA clone encoding MBF1 was isolated from the silkworm Bombyx mori whose sequence predicts a basic protein consisting of 146 amino acids. Bacterially expressed recombinant MBF1 is functional in interactions with TBP and a positive cofactor MBF2. The recombinant MBF1 also makes a direct contact with FTZ-F1 through the C-terminal region of the FTZ-F1 DNA-binding domain and stimulates the FTZ-F1 binding to its recognition site. The central region of MBF1 (residues 35-113) is essential for the binding of FTZ-F1, MBF2, and TBP. When the recombinant MBF1 was added to a HeLa cell nuclear extract in the presence of MBF2 and FTZ622 bearing the FTZ-F1 DNA-binding domain, it supported selective transcriptional activation of the fushi tarazu gene as natural MBF1 did. Mutations disrupting the binding of FTZ622 to DNA or MBF1, or a MBF2 mutation disrupting the binding to MBF1, all abolished the selective activation of transcription. These results suggest that tethering of the positive cofactor MBF2 to a FTZ-F1-binding site through FTZ-F1 and MBF1 is essential for the binding site-dependent activation of transcription. A homology search in the databases revealed that the deduced amino acid sequence of MBF1 is conserved across species from yeast to human.

Transcriptional activation through interaction of MBF2 with TFIIA

BACKGROUND

Transcriptional activation of the Drosopohila melanogaster fushi tarzu gene by FTZ-F1 or its silkworm counterpart BmFTZ-F1 requires two cofactors MBF1 and MBF2 which do not directly bind to DNA. MBF1 is a bridging molecule that connects FTZ-F1 (or BmFTZ- F1), MBF2 and TATA binding protein TBP. MBF2 is a positive cofactor that activates transcription.

RESULTS

To elucidate the mechanism of transcriptional activation by MBF2, we isolated a cDNA coding for the factor. Northern blot analyses showed temporally restricted expression of MBF2 mRNA similar to that of BmFTZ-F1 mRNA. The cDNA sequence predicts a polypeptide of 10 kDa whereas natural MBF2 is a glycoprotein of 22 kDa. The deduced amino acid sequence of the factor showed no homology with proteins in the databases. Farwestern analyses and glutathione S-transferase interaction assays demonstrated that MBF2 makes a direct contact with the beta-subunit of TFIIA. In a HeLa cell nuclear extract, bacterially expressed recombinant MBF2 activated transcription from various promoters as natural MBF2 did. This activation requires the MBF2-TFIIA interaction. When recombinant MBF2 was added to the HeLa cell nuclear extract in the presence of MBF1 and FTZ622 bearing the DNA-binding region of FTZ-F1, it selectively activated transcription of the fushi tarazu gene. This selective activation also requires the MBF2-TFIIA interaction.

CONCLUSION

MBF2 activates transcription through its interaction with TFIIA. Selective transcriptional activation occurs when MBF2 is recruited to a promoter carrying the FTZ-F1 binding site by FTZ-F1 and MBF1.

Preferential MyoD homodimer formation demonstrated by a general method of dominant negative mutation employing fusion with a lysosomal protease

We report on a general strategy for engineering dominant negative mutations that, in principle, requires neither extensive structural or functional knowledge of the targeted protein. The approach consists of fusing the lysosomal protease cathepsin B (CB) to a subunit of a multimeric protein. The CB fusion polypeptide can proteolytically digest the multimer and/or detour the multimer from its usual subcellular destination to the lysosome. We first demonstrate the general validity of the approach with CB fusion to E. coli lacZ, encoding tetrameric beta-galactosidase. Cotransfection of NIH 3T3 cells with a vector expressing a CB-lacZ fusion inhibits the beta-galactosidase activity produced by transfection of lacZ alone. We infer that the dominant negative inhibition results from both direct proteolysis of the beta-galactosidase tetramer by the fusion subunit and detour of the tetramer to the lysosome. In a specific application of this strategy, we have fused CB to the dimeric bHLH skeletal muscle transcription factor MyoD. The CB-MyoD fusion protein localizes to the cytoplasm, presumably the lysosome, demonstrating the dominance of lysosomal localization to nuclear localization. The CB-MyoD fusion appears to divert homodimerizing native MyoD from its usual nuclear destination, consequently inhibiting MyoD-mediated transactivation and in vitro differentiation of C2C12 myoblasts. Surprisingly, the CB-MyoD fusion fails to interact with the bHLH heterodimerization partners, E12 and E47, suggesting preferential MyoD homodimer formation, at least in the prenuclear cellular compartments.

Sequences of two cDNAs encoding silkworm homologues of Drosophila melanogaster squid gene

The squid (sqd) gene of Drosophila melanogaster encodes a few isoforms of a heterogeneous nuclear (hn) RNA-binding protein. We isolated two types of cDNAs coding for homologues of the Sqd protein from the silkworm Bombyx mori. The two predicted amino acid (aa) sequences are identical up to aa 280 and then diverge. The silkworm and fruit fly proteins share 80% homology in the RNA-binding motif region. These cDNAs detect 2.0-, 1.8- and 1-kb mRNAs in the middle and posterior silk glands.

Mediators of activation of fushi tarazu gene transcription by BmFTZ-F1

Transcriptional activation by many eukaryotic sequence-specific regulators appears to be mediated through transcription factors which do not directly bind to DNA. BmFTZ-F1 is a silkworm counterpart of FTZ-F1, a sequence-specific activator of the fushi tarazu gene in Drosophila melanogaster. We report here the isolation of 18- and 22-kDa polypeptides termed MBF1 and MBF2, respectively, that form a heterodimer and mediate activation of in vitro transcription from the fushi tarazu promoter by BmFTZ-F1. Neither MBF1, MBF2, nor a combination of them binds to DNA. MBF1 interacts with BmFTZ-F1 and stabilizes the BmFTZ-F1-DNA complex. MBF1 also makes direct contact with TATA-binding protein (TBP). Both MBF1 and MBF2 are necessary to form a complex between BmFTZ-F1 and TBP. We propose a model in which MBF1 and MBF2 form a bridge between BmFTZ-F1 and TBP and mediate transactivation by stabilizing the protein-DNA interactions.

Saliva and serum CA 125 assays for detecting malignant ovarian tumors

The aim of this study was to determine whether CA 125 was present in saliva and, if it was present, to compare saliva and serum levels in patients with pelvic masses in order to determine whether saliva assays would be useful in identifying patients with ovarian malignancies. Saliva and serum CA 125 levels were assayed in specimens obtained from 55 normal healthy women, 92 patients with benign pelvic masses, and 41 patients with malignant pelvic tumors. We defined a serum CA 125 value greater than 65 U/mL and a saliva CA 125 value greater than 3000 U/mL as the positivity criteria. No serum or saliva assay was positive in the 55 normal women. The sensitivities of the saliva and serum CA 125 assays in 16 patients with epithelial ovarian cancer were 81.3 and 93.8%, respectively. A linear correlation was observed between serum and saliva CA 125 levels. The false-positive rates of serum CA 125 in patients with endometriomas and pelvic tuberculosis were 72.7 and 80%, respectively, but the false-positive rates for saliva CA 125 assays were only 13.6 and 10%, respectively. Therefore, the saliva CA 125 assay had a better diagnostic value than the serum CA 125 assay. In addition, collection of saliva is simple, noninvasive, and inexpensive, and samples could be obtained easily and repeatedly. For these reasons, assays of saliva CA 125 levels may be a new way of screening for malignant ovarian tumors.

[Primary research on saliva and serum CA125 assays for detecting malignant ovarian tumors]

Saliva and serum CA125 levels were assayed in specimens obtained from 55 normal healthy women, 92 patients with benign pelvic masses and 41 patients with malignant pelvic tumors. A saliva CA125 value greater than 3,000 kU/ml and serum CA125 value greater than 65 kU/ml were defined as positive. Only one saliva assay was positive in 55 normal women. The sensitivity of saliva and serum CA125 assays in 16 patients with epithelial ovarian cancer was 81% and 94% respectively. A linear correlation was observed between serum and saliva CA125 levels in 32 patients with malignant ovarian cancer. The false positive rate of saliva and serum CA125 assays in patients with endometriomas and pelvic tuberculosis was 13.6%, 10% and 72.7%, 80% respectively. Therefore, the saliva CA125 assay had better diagnostic value than the serum CA125 assay. In addition, collection of saliva is simple, noninvasive, and inexpensive and could be obtained repeatedly. For these reasons, assays of saliva CA125 levels may provide a new way of screening for malignant ovarian tumors.

Effects of traces of rare earth elements on the protozoan Blepherisma and on mice

The growth of the protozoan Blepherisma is stimulated by Lanthanum (La) at concentrations as low as 0.32 ppm. In mice Yttrium (Y) and Ytterbium (Yb) are absorbed, accumulated, and metabolized. Both rare earth elements (RE) exhibit a high affinity for teeth and bones, accumulation occurs and metabolism is slow. In the livers of RE-exposed mice, concentrations are variable. The liver is apparently capable of absorbing and discharging RE in a manner depending on metabolic activity. The main route of discharge for ingested REs is the alimentary canal. Exposure of pregnant mice to RE leads to rapid placental transfer of RE; 14.1% of the total amount of RE administered was detected in newborn mice. Young, developing organisms appear to be especially susceptible to RE accumulation.

[Experimental chemotherapy of human gastric cancer cell lines in vitro and in nude mice]

Cytotoxic effects of allyl trisulfide (Alt, a synthetic chemical identical with one of the main active principles of garlic), 5 FU, MMC and DDP on SGC 7901 ( a moderately differentiated human gastric adenocarcinoma cell line) and MGC 803 (a poorly differentiated human gastric mucoadenocarcinoma cell line) had been reported before. In this paper, effects of repeated two doses of each drug and the combination of two drugs on these two cell lines were studied using relative clone-survival test. The inhibitory effects of Alt, MMC alone or combined on MGC tumor in nude mice were observed. No drug resistance was found when any one of the four agents at the same concentration were repeated twice separately at 60 hour interval in vitro. The cytotoxic effect of the repeated two doses was approximately equal to that of the single dose at double concentration. The in vitro test of combinations of two drugs showed that Alt plus MMC or 5 FU plus DDP had markedly synergistic effect on MGC cells; 5 FU plus DDP had markedly synergistic effect on SGC cells. The inhibition test on the growth of MGC tumor in nude mice indicated that the inhibition rates of Alt, MMC alone or combined were 58.3%, 86.3% and 84.3%. The systemic toxic effect of MMC alone was severe, whereas Alt alone or MMC plus Alt showed mild toxicity. For this reason, Alt plus MMC is recommended for clinical trials on poorly differentiated gastric cancer. In addition, for the comparison of in vitro test dose and clinical dose of each drug, the principle of clinical adult dose range (CADR) is proposed.

[Establishment of a human pulmonary adenocarcinoma cell line Lu-YePa and its biological characteristics]

This paper presents the establishment of a human pulmonary adenocarcinoma cell line Lu-YePa and its biological characteristics. The primary cells of Lu-YePa cell line were derived from a twenty six year old patient with poorly differentiated adenocarcinoma of the lung. After 36 days' culture, transfer was made and the cells proliferated steadily and rapidly afterwards. The doubling time was 34.6 hours. Mitotic index reached 49.5% on day 5. Chromosome number was subtriploid with the mode of 62. The large submetacentric marker chromosome was presented in 68% of cells. PAS positive granules were found in the cytoplasm. The study of concanavalin A condensation, electron microscopic observation, heterotransplantation and plating efficiency indicates that Lu-YePa cells are concordant with the human pulmonary adenocarcinoma cells in morphology and biological behavior.