Dual targeting of Mcl-1 and Bcl-2 to overcome chemoresistance in cervical and colon cancer

After an initial positive response to chemotherapy, cancer patients often become resistant and experience relapse. Our previous research identified eukaryotic translation initiation factor 4E (eIF4E) as a crucial target to overcome chemoresistance. In this study, we delved further into the role and therapeutic potential of myeloid cell leukemia 1 (Mcl-1), an eIF4E-mediated target, in chemoresistance. We showed that the levels of phosphor and total eIF4E, as well as Mcl-1, were elevated in chemoresistant cervical but not colon cancer cells. Mcl-1 inhibitor S64315 decreased Mcl-1 levels in chemoresistant cancer cells, regardless of Mcl-1 upregulation, decreased viability in chemoresistant cancer cells and acted synergistically with chemotherapy drugs. The combined inhibition of Mcl-1 and B-cell lymphoma 2 (Bcl-2), employing both genetic and pharmacological approaches, led to a markedly more substantial decrease in viability compared with the inhibition of either target individually. The combination of S64315 and Bcl-2 inhibitors reduced tumor growth in chemoresistant cervical and colon cancer models without causing general toxicity in mice. This combination also prolonged overall survival compared with using S64315 or venetoclax alone. Our research highlights the therapeutic potential of inhibiting Mcl-1 and Bcl-2 simultaneously in chemoresistant cancers and provides a rationale for initiating clinical trials to investigate the combination of S64315 and venetoclax for the treatment of advanced colon and cervical cancer.

Targeting glutamine metabolism exhibits anti-tumor effects in thyroid cancer

BACKGROUND

Effective treatment for patients with advanced thyroid cancer is lacking. Metabolism reprogramming is required for cancer to undergo oncogenic transformation and rapid tumorigenic growth. Glutamine is frequently used by cancer cells for active bioenergetic and biosynthetic needs. This study aims to investigate whether targeting glutamine metabolism is a promising therapeutic strategy for thyroid cancer.

METHODS

The expression of glutaminase (GLS) and glutamate dehydrogenase (GDH) in thyroid cancer tissues was evaluated by immunohistochemistry, and glutamine metabolism-related genes were assessed using real time-qPCR and western blotting. The effects of glutamine metabolism inhibitor 6-diazo-5-oxo-l-norleucine (DON) on thyroid cancer cells were determined by CCK-8, clone formation assay, Edu incorporation assay, flow cytometry, and Transwell assay. The mechanistic study was performed by real time-qPCR, western blotting, Seahorse assay, and gas chromatography-mass spectrometer assay. The effect of DON prodrug (JHU-083) on thyroid cancer in vivo was assessed using xenograft tumor models in BALB/c nude mice.

RESULTS

GLS and GDH were over-expressed in thyroid cancer tissues, and GLS expression was positively associated with lymph-node metastasis and TNM stage. The growth of thyroid cancer cells was significantly inhibited when cultured in glutamine-free medium. Targeting glutamine metabolism with DON inhibited the proliferation of thyroid cancer cells. DON treatment did not promote apoptosis, but increased the proportion of cells in the S phase, accompanied by the decreased expression of cyclin-dependent kinase 2 and cyclin A. DON treatment also significantly inhibited the migration and invasion of thyroid cancer cells by reducing the expression of N-cadherin, Vimentin, matrix metalloproteinase-2, and matrix metalloproteinase-9. Non-essential amino acids, including proline, alanine, aspartate, asparagine, and glycine, were reduced in thyroid cancer cells treated with DON, which could explain the decrease of proteins involved in migration, invasion, and cell cycle. The efficacy and safety of DON prodrug (JHU-083) for thyroid cancer treatment were verified in a mouse model. In addition to suppressing the proliferation and metastasis potential of thyroid cancer in vivo, enhanced innate immune response was also observed in JHU-083-treated xenograft tumors as a result of decreased expression of cluster of differentiation 47 and programmed cell death ligand 1.

CONCLUSIONS

Thyroid cancer exhibited enhanced glutamine metabolism, as evidenced by the glutamine dependence of thyroid cancer cells and high expression of multiple glutamine metabolism-related genes. Targeting glutamine metabolism with DON prodrug could be a promising therapeutic option for advanced thyroid cancer.

Inhibition of ubiquitin specific peptidase 8 is effective against 5-fluorouracil resistance in colon cancer via suppressing EGFR and EGFR-mediated signaling pathways

BACKGROUND

The identification of a sensitizing strategy to overcome 5-fluorouracil (5-FU) therapeutic resistance is needed in colon cancer. Recent studies highlight the oncogenic role of ubiquitin specific peptidase 8 (USP8) in many cancers. In line with these efforts, this work investigated the therapeutic potential of targeting USP8 in colon cancer.

METHODS

Immunohistochemistry was performed to determine USP8 expression level in colon cancer tissues and their adjacent normal tissues. Gain-of-function analysis via plasmid overexpression and loss-of-function analysis via siRNA knockdown were applied on cellular assays. The combinatory effects of USP8 inhibitor and cisplatin were determined using a colon xenograft mouse model. Immunoblotting was performed to investigate the molecular mechanism of USP8 inhibition in colon cancer cells.

RESULTS

Compared to normal counterparts, we showed that USP8 protein level was significantly higher in colon cancer tissues and cells. In addition, USP8 expression was not affected by prolonged exposure of colon cancer cells to 5-FU. USP8 was important for colon cancer cell growth and survival but not migration as assessed by loss-of-function and gain-of-function approaches. Pharmacological inhibition of USP8 using USP8 inhibitor is active against both sensitive and 5-FU-resistant colon cancer cells. Of note, USP8 inhibitor significantly inhibited colon cancer formation and growth, and augmented in vivo efficacy of 5-FU without causing toxicity in mice. Mechanistic studies showed that USP8 inhibitor acted on colon cancer cells through suppressing EGFR and EGFR-mediated signalling pathways.

CONCLUSIONS

Our work is the first to reveal the essential role of USP8 in colon cancer via EGFR oncogenic signalling pathways. Our findings provide a proof-of-concept that USP8 inhibitors are promising candidates to overcome 5-FU resistance in colon cancer.

Higher Cognitive Reserve Is Beneficial for Cognitive Performance Via Various Locus Coeruleus Functional Pathways in the Pre-Dementia Stage of Alzheimer's Disease

BACKGROUND

Cognitive reserve (CR) shows protective effects on cognitive function in older adult and in Alzheimer's disease (AD). However, the brain mechanisms underlying the CR effect on the non-dementia AD spectrum (subjective cognitive decline (SCD) and mild cognitive impairment (MCI)) are unknown. The aim of this study was to investigate the potential moderate effect of CR on brain functional networks associated with cognitive performance.

METHODS

We selected 200 participants, including 48 cognitively normal (CN) and 56 SCD, and 96 patients with MCI from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Seed-based locus coeruleus functional connectivity (LC FC) was conducted to detect early brain functional changes in the non-dementia AD spectrum. CR was assessed via years of education and intelligence (IQ). The ANDI composite executive function scores (ADNI-EF) and ADNI composite memory scores (ANDI-MEM) at baseline and 24-month follow-up were used to assess cognitive performance.

RESULTS

Compared to the CN group, the SCD group showed abnormal LC FC with the executive control network (dorsolateral prefrontal cortex, DLPFC), salience network, sensorimotor network, reward network, and hippocampus, while these alterations were inverted at the MCI stage. The LC-hippocampus FC was correlated with ADNI-MEM at baseline and follow-up, and these relationships were moderated by education. The LC-DLPFC FC was correlated with ADNI-EF at baseline, and this association was moderated by IQ.

CONCLUSION

Our results manifested that higher levels of CR would confer protective effects on SCD and MCI. Furthermore, IQ and education could moderate the relationship between LC FC and cognition through different pathways.

The MuSK-BMP pathway regulates synaptic Nav1.4 localization and muscle excitability

The neuromuscular junction (NMJ) is the linchpin of nerve-evoked muscle contraction. Broadly considered, the function of the NMJ is to transduce a nerve action potential into a muscle fiber action potential (MFAP). Efficient information transfer requires both cholinergic signaling, responsible for the generation of endplate potentials (EPPs), and excitation, the activation of postsynaptic voltage-gated sodium channels (Nav1.4) to trigger MFAPs. In contrast to the cholinergic apparatus, the signaling pathways that organize Nav1.4 and muscle fiber excitability are poorly characterized. Muscle-specific kinase (MuSK), in addition to its Ig1 domain-dependent role as an agrin-LRP4 receptor, is also a BMP co-receptor that binds BMPs via its Ig3 domain and shapes BMP-induced signaling and transcriptional output. Here we probed the function of the MuSK-BMP pathway at the NMJ using mice lacking the MuSK Ig3 domain ('ΔIg3-MuSK'). Synapses formed normally in ΔIg3-MuSK animals, but the postsynaptic apparatus was fragmented from the first weeks of life. Anatomical denervation was not observed at any age examined. Moreover, spontaneous and nerve-evoked acetylcholine release, AChR density, and endplate currents were comparable to WT. However, trains of nerve-evoked MFAPs in ΔIg3-MuSK muscle were abnormal as revealed by increased jitter and blocking in single fiber electromyography. Further, nerve-evoked compound muscle action potentials (CMAPs), as well as twitch and tetanic muscle torque force production, were also diminished. Finally, Nav1.4 levels were reduced at ΔIg3-MuSK synapses but not at the extrajunctional sarcolemma, indicating that the observed excitability defects are the result of impaired localization of this voltage-gated ion channel at the NMJ. We propose that MuSK plays two distinct roles at the NMJ: as an agrin-LRP4 receptor necessary for establishing and maintaining cholinergic signaling, and as a BMP co-receptor required for maintaining proper Nav1.4 density, nerve-evoked muscle excitability and force production. The MuSK-BMP pathway thus emerges as a target for modulating excitability and functional innervation, which are defective in conditions such as congenital myasthenic syndromes and aging.

LncRNA LINC01278 accelerates colorectal cancer progression via miR-134-5p/KDM2A axis

OBJECTIVE

Long non-coding RNAs (lncRNAs) play vital roles in the pathogenesis and development of multiple cancers, including colorectal cancer (CRC). Nevertheless, the regulatory mechanisms of LINC01278 in CRC remain unknown. Our research aims to identify the regulatory mechanisms of LINC01278 in CRC.

PATIENTS AND METHODS

The expression of LINC01278 was examined by quantitative real-time polymerase chain reaction (RT-qPCR). StarBase and TargetScan websites were used to predict the interaction between miR-134 and LINC01278 or KDM2A, which was further confirmed by Dual-Luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Cell viability, migration, and invasion were detected by Cell Counting Kit-8 (CCK-8) and transwell assays.

RESULTS

LINC01278 was upregulated in CRC tissues and cell lines, and knockdown of LINC01278 suppressed CRC cell progression. In addition, LINC01278 inhibited miR-134 expression by direct interaction, and the inhibition of miR-134 abolished the suppressive effects of LINC01278 knockdown on viability, migration, and invasion of CRC cells. Furthermore, KDM2A was confirmed to be a target gene of miR-134. Overexpression of KDM2A facilitated the tumorigenesis of CRC, while this effect was reversed by the upregulation of miR-143. Finally, it was demonstrated that miR-134 inhibitor reversed the shLINC01278‑mediated inhibitory effect on KDM2A expression.

CONCLUSIONS

Our study demonstrated that LINC01278 upregulated KDM2A to promote CRC progression by interacting with miR-143, suggesting that LINC01278 might be a new therapeutic target of CRC.

Comparison of the clinical outcomes of skin bridge loop ileostomy and traditional loop ileostomy in patients with low rectal cancer

To compare the clinical results of patients with low rectal cancer who underwent skin bridge loop ileostomy and traditional loop ileostomy, and provide clinical evidence for choosing a better ostomy method. We retrospectively collected data of 118 patients with rectal cancer who underwent low anterior resection and loop ileostomy. To investigate the patients characteristics, postoperative stoma-related complications and the frequency of exchanged ostomy bags. The differences of these indicators between the two groups of patients who underwent skin bridge loop ileostomy and traditional loop ileostomy were compared. The Visual Analog Scale (VAS) score of the skin bridge loop ileostomy group was lower than that of the traditional ileostomy loop group (P < 0.05). The skin bridge group had a lower Discoloration, Erosion, Tissue overgrowth (DET) score and incidence of mucocutaneous separation than the traditional group at the 1st and 2nd weeks after operation (P < 0.05). The average number of weekly exchanged ostomy bags was significantly less in the skin bridge group than in the traditional group within 4 weeks after surgery (P < 0.05). Our experience demonstrates that the skin bridge loop ileostomy may significantly reduce early postoperative stoma-related complications, the frequency of exchanged ostomy bags and patients' medical costs after discharge.

Effects of blood pathological changes before TAI on pregnancy of dairy cows with anestrus and estrus

ABSTRACT The objective of this study was to investigate the influence of plasma pathological changes before timed artificial insemination (TAI) on pregnancy of cows. The contents of estrogen (E2), progesterone (P4), glucose (Glu), selenium (Se), brain-derived neurotrophic factor (BDNF), and histamine (HIS) in plasma of 48 Holstein cows were measured before TAI. According to the estrus detection, the cows were divided into estrus (E) and anestrus (A) groups. After pregnancy testing at 28 d after TAI, two groups of E and A were divided into positive pregnancy of E group (EP+), negative pregnancy of E group (EP-), positive pregnancy of A group (AP+), and negative pregnancy of A group (AP-). The contents of E2, P4, Glu, Se, BDNF and hIS significantly differed among the four groups (P<0.01). The ROC analysis was used to determine the risk of negative pregnancy test (-) after TAI was increased when plasma E2 was less than 46.45 pmol/L in cows before TAI. The changes in E2, P4,hIS, Glu, and BDNF in the blood of natural estrus and natural anestrus cows affected the pregnancy after TAI. the level of E2 in plasma may be used to assess the risk of negative pregnancy after TAI.

SNHG20/miR-140-5p/NDRG3 axis contributes to 5-fluorouracil resistance in gastric cancer

5-fluorouracil (5-FU)-based chemotherapy is the first line treatment for advanced gastric cancer. However, the effectiveness of 5-FU is limited by drug resistance. The N-myc downstream-regulated gene, family member 3 (NDRG3) is a member of the NDRG family and has been implicated in numerous types of cancer. However, the role of NDRG3 in gastric cancer remains unclear. In the present study, NDRG3 mRNA expression in gastric cancer and adjacent normal tissues was analyzed using the Gene Expression Profiling Interactive Analysis web tool. NDRG3 expression was silenced using short hairpin RNAs to examine the effect of NDRG3 on the growth of gastric cancer cells. Potential regulators of NDRG3 were identified using the TargetScan and MicroRNA tools and verified by a luciferase assay and reverse transcription-quantitative PCR analysis. The current study demonstrated that NDRG3 was upregulated in gastric cancer specimens and promoted cell proliferation in gastric cancer cell lines. Furthermore, the present study revealed that the small nucleolar RNA host gene 20 (SNHG20)/microRNA (miR)-140-5p signaling pathway may regulate the expression of NDRG3. SNHG20 was revealed to be involved in mediating resistance to 5-FU in gastric cancer cell lines via NDRG3. In conclusion, the results of the present study suggest that the SNHG20/miR-140-5p/NDRG3 axis may be involved in mediating resistance to 5-FU in gastric cancer.

Inhibition of cyclin-dependent kinases by AT7519 is effective to overcome chemoresistance in colon and cervical cancer

Cyclin-dependent kinases (CDK), a family of heterodimeric kinases that play central roles in regulation of cell cycle progression and transcription, have garnered attention in recent years because their aberrant activity has been reported in a wide variety of human cancers. AT7519 is a multitargeted CDK inhibitor that is currently in clinical trials for the treatment of refractory blood cancers. In this work, we are the first to provide preclinical evidence that AT7519 is an attractive candidate to overcome chemoresistance in colon and cervical cancer. We show that AT7519 is effective in targeting a panel of colon and cervical cancer cell lines, with IC50 range from 0.1 to 1 μM. Importantly, AT7519 at similar IC50 range inhibits growth and induces apoptosis of paclitaxel-resistant cervical cancer cells and 5-FU-resistant colon cancer cells. AT7519 at sublethal concentration remarkably augments the inhibitory effects of 5-FU and paclitaxel in colon and cervical cancer cells. Mechanistically, we show that AT7519 suppresses phosphorylation of CDK1, CDK2 and RNA polymerase II in chemoresistant colon and cervical cancer cells. We further confirm the efficacy of AT7519 and its mechanisms of the action using two independent chemoresistant xenograft mouse models: 5-FU-resistant colony cancer xenograft and paclitaxel-resistant cervical cancer xenograft. Our findings support the clinical trials of AT7519 for cancer treatment. Our work also demonstrates the therapeutic value of inhibiting CDK in chemoresistant cancers.

Migration of a foreign body to the rectum: A case report and literature review

RATIONALE

Rectal foreign bodies are not an uncommon finding in outpatient departments globally. Most such objects are inserted through the anus. Occasionally, a foreign body may be ingested and may successfully pass through the entire gastrointestinal tract and be held up in the rectum. In extremely rare cases, foreign bodies in adjacent tissues or organs can penetrate the rectal wall and enter the rectal lumen. We report a rare case that the IUCD had migrated and was embedded in the rectal wall. A part of the IUCD was loosened and deformed into a metallic wire that protruded through the anus.

PATIENT CONCERNS

A 45-year-old woman presented with complaints of a metallic wire protruding through her anus when she used the washroom. The wire would become longer when she manually pulled it; however, this process was associated with pain in the lower abdomen, and she therefore stopped manipulating it.

DIAGNOSES

A rectal foreign body secondary to intrauterine contraceptive device (IUCD) migration and rectal perforation, as well as a pelvic cyst.

INTERVENTIONS

Under general anesthesia, she underwent laparoscopic removal of the rectal foreign body, pelvic adhesiolysis, pelvic cyst resection, and ileostomy combined with colonoscopy.

OUTCOMES

Her postoperative recovery was uneventful.

LESSONS

Foreign bodies in adjacent tissues or organs can penetrate the rectal wall and enter the rectal lumen. Regular follow-up after IUCD insertion is very important. We report this rare case that would increase awareness among clinicians regarding the differential diagnosis and treatment in such cases.

Inhibition of eukaryotic translation initiation factor 4E is effective against chemo-resistance in colon and cervical cancer

Although cancer patients initially respond well to chemotherapy, they eventually develop resistance and relapse. In this work, we demonstrate that eIF4E-targeting therapy is a potential sensitizing strategy for overcoming chemoresistance and progression in cancer. We show that ribavirin, an anti-viral drug and pharmacological eIF4E inhibitor, effectively inhibits proliferation and decreases viability of paclitaxel-resistant cervical cancer and 5-FU-resistant colon cancer cells while is less toxic to human fibroblast cells. Importantly, oral administration of ribavirin significantly inhibits paclitaxel-resistant colon and 5-FU-resistant cervical cancer growth in xenograft mouse cancer model without causing significant toxicity in mice. Consistently, combination of ribavirin with paclitaxel or 5-FU sensitizes colon and cervical cancer cells to chemotherapeutic agents treatment in vitro and in vivo. We further confirm that the mechanism of the action of ribavirin in chemoresistant cancer cells is through suppressing eIF4E function. In addition, specific eIF4E knockdown via two independent siRNA mimics the effects of ribavirin in chemoresistant colon and cervical cancer cells. Cell cycle analysis indicate that ribavirin enhances the anti-proliferative effect of 5-FU by additionally arresting cells at G2/M phase via increasing cyclin B1, p-histone H3(Ser10) and Mad2 levels. Our work demonstrates that eIF4E inhibition using inhibitor or siRNA, either as single agent or in combination, could sensitize chemoresistant cancer cells to paclitaxel or 5-FU treatment and thereby improving the efficacy of chemodrug. Our findings demonstrate the therapeutic value of inhibiting eIF4E, particularly in chemoresistant cancers. Our findings also suggest ribavirin as a promising sensitizing drug for cancer treatment.

The effect of interactions between a bacterial strain isolated from drinking water and a pathogen surrogate on biofilms formation diverged under static vs flow conditions

AIMS

Interactions with water bacteria affect the incorporation of pathogens into biofilms and thus pathogen control in drinking water systems. This study was to examine the impact of static vs flow conditions on interactions between a pathogen and a water bacterium on pathogen biofilm formation under laboratory settings.

METHODS AND RESULTS

A pathogen surrogate Escherichia coli and a drinking water isolate Stenotrophomonas maltophilia was selected for this study. Biofilm growth was examined under two distinct conditions, in flow cells with continuous medium supply vs in static microtitre plates with batch culture. E. coli biofilm was greatly stimulated (c. 2-1000 times faster) with the presence of S. maltophilia in flow cells, but surprisingly inhibited (c. 65-95% less biomass) in microtitre plates. These divergent effects were explained through various aspects including surface attachment, cellular growth, extracellular signals and autoaggregation.

CONCLUSIONS

Interactions with the same water bacterium resulted in different effects on E. coli biofilm formation when culture conditions changed from static to flow.

SIGNIFICANCE AND IMPACT OF STUDY

This study highlights the complexity of species interactions on biofilm formation and suggests that environmental conditions such as the flow regime can be taken into consideration for the management of microbial contamination in drinking water systems.

Pharmacokinetic and pharmacodynamic integration and modeling of acetylkitasamycin in swine for Clostridium perfringens

The aim of this study was to establish an integrated pharmacokinetic/pharmacodynamic (PK/PD) modeling approach of acetylkitasamycin for designing dosage regimens and decreasing the emergence of drug-resistant bacteria. After oral administration of acetylkitasamycin to healthy and infected pigs at the dose of 50 mg/kg body weights (bw), a rapid and sensitive LC-MS/MS method was developed and validated for determining the concentration change of the major components of acetylkitasamycin and its possible metabolite kitasamycin in the intestinal samples taken from the T-shape ileal cannula. The PK parameters, including the integrated peak concentration (C_max ), the time when the maximum concentration reached (T_max ) and the area under the concentration-time curve (AUC), were calculated by WinNonlin software. The minimum inhibitory concentration (MIC) of 60 C. perfringens strains was determined following CLSI guideline. The in vitro and ex vivo activities of acetylkitasamycin in intestinal tract against a pathogenic strain of C. perfringens type A (CPFK122995) were established by the killing curve. Our PK data showed that the integrated C_max , T_max , and AUC were 14.57-15.81 μg/ml, 0.78-2.52 hR, and 123.84-152.32 μg hr/ml, respectively. The PD data show that MIC₅₀ and MIC₉₀ of the 60 C. perfringens isolates were 3.85 and 26.45 μg/ml, respectively. The ex vivo growth inhibition data were fitted to the inhibitory sigmoid E_max equation to provide the values of AUC/MIC to produce bacteriostasis (4.84 hr), bactericidal activity (15.46 hr), and bacterial eradication (24.99 hr). A dosage regimen of 18.63 mg/kg bw every 12 hr could be sufficient in the prevention of C. perfringens infection. The therapeutic dosage regimen for C. perfringens infection was at the dose of 51.36 mg/kg bw every 12 hr for 3 days. In summary, the dosage regimen for the treatment of C. perfringens in pigs administered with acetylkitasamycin was designed using PK/PD integrate model. The designed dose regimen could to some extent decrease the risk for emergence of macrolide resistance.

Evaluation of the ability of Acinetobacter baumannii to form biofilms on six different biomedical relevant surfaces

The human opportunistic pathogen, Acinetobacter baumannii, has the propensity to form biofilms and frequently cause medical device-related infections in hospitals. However, the physio-chemical properties of medical surfaces, in addition to bacterial surface properties, will affect colonization and biofilm development. The objective of this study was to compare the ability of A. baumannii to form biofilms on six different materials common to the hospital environment: glass, porcelain, stainless steel, rubber, polycarbonate plastic and polypropylene plastic. Biofilms were developed on material coupons in a CDC biofilm reactor. Biofilms were visualized and quantified using fluorescent staining and imaged using confocal laser scanning microscopy (CLSM) and by direct viable cell counts. Image analysis of CLSM stacks indicated that the mean biomass values for biofilms grown on glass, rubber, porcelain, polypropylene, stainless steel and polycarbonate were 0·04, 0·26, 0·62, 1·00, 2·08 and 2·70 μm(3) /μm(2) respectively. Polycarbonate developed statistically more biofilm mass than glass, rubber, porcelain and polypropylene. Viable cell counts data were in agreement with the CLSM-derived data. In conclusion, polycarbonate was the most accommodating surface for A. baumannii ATCC 17978 to form biofilms while glass was least favourable. Alternatives to polycarbonate for use in medical and dental devices may need to be considered.

SIGNIFICANCE AND IMPACT OF THE STUDY

In the hospital environment, Acinetobacter baumannii is one of the most persistent and difficult to control opportunistic pathogens. The persistence of A. baumannii is due, in part, to its ability to colonize surfaces and form biofilms. This study demonstrates that A. baumannii can form biofilms on a variety of different surfaces and develops substantial biofilms on polycarbonate - a thermoplastic material that is often used in the construction of medical devices. The findings highlight the need to further study the in vitro compatibility of medical materials that could be colonized by A. baumannii and allow it to persist in hospital settings.

Mini-review: Microbial coaggregation: ubiquity and implications for biofilm development

Coaggregation is the specific recognition and adherence of genetically distinct microorganisms. Because most biofilms are polymicrobial communities, there is potential for coaggregation to play an integral role in spatiotemporal biofilm development and the moderation of biofilm community composition. However, understanding of the mechanisms contributing to coaggregation and the relevance of coaggregation to biofilm ecology is at a very early stage. The purpose of this review is to highlight recent advances in the understanding of microbial coaggregation within different environments and to describe the possible ecological ramifications of such interactions. Bacteria that coaggregate with many partner species within different environments will be highlighted, including oral streptococci and oral bridging organisms such as fusobacteria, as well as the freshwater sphingomonads and acinetobacters. Irrespective of environment, it is proposed that coaggregation is essential for the orchestrated development of multi-species biofilms.

Processing and export of peptide pheromones and bacteriocins in Gram-negative bacteria

Cell-density-dependent gene expression is widespread in bacteria and is mediated by extracellular communication molecules. Gram-negative bacteria often use N-acyl homoserine lactones, whereas cell-cell signaling in Gram-positive bacteria is accomplished using post-translationally processed peptide pheromones. In many Gram-positive bacteria, export of these peptides requires the activity of a dedicated ATP-binding cassette (ABC) transporter, which cleaves off a typical leader peptide termed the double-glycine leader sequence concomitant with translocation across the membrane. Inspection of bacterial genome sequences has revealed the presence of similar ABC transporters, as well as genes encoding peptides with double-glycine-type leader sequences in Gram-negative bacteria, and it is suggested that the postulated transported peptides could perform a signaling function.

Use of Dual Marker Transposons to Identify New Symbiosis Genes in Rhizobium

Rhizobium etli elicits nitrogen-fixing nodules on the roots of Phaseolus vulgaris. Using a composite dual-marker mini-Tn5 transposon carrying combinations of a constitutively expressed gfp gene and a promoterless gusA gene, we identified novel genes required for an efficient symbiosis. The induction of the gusA gene was used to determine the expression level of the different target genes under conditions partly mimicking the symbiotic environment ex planta. The green fluorescence was used to localize the bacteria in infection threads or inside the plant cells. Among the identified R. etli mutants, several produced a Nod- phenotype, whereas others were Fix- or displayed a reduced acetylene reduction activity during symbiosis. Partial sequence analysis of the mutated genes allowed us to classify them as nodulation genes, nitrogen fixation genes, genes possessing various enzymatic functions previously not yet associated with symbiosis, and genes displaying no similarity to any other sequence in the database. This methodology can be used to screen large numbers of mutants in the search for novel genes important for Rhizobium-legume symbiosis, and may be adapted to study other plant-bacterium interactions.

[Environmental impact of oil pollutant on groundwater during oilfield exploitation in Daqing--a modelling analysis]

This paper analyzed the pollution sources and paths of groundwater environment in Longnan of Daqing during oilfield exploitation. Based on the technological characteristics of oilfield exploitation, a mathematical model on the migration and transformation of oil pollutants was developed, in which, the degradability and the adsorption capacity of oil pollutants were taken into account. An analytical formula of oil pollutant migration in groundwater was derived with continuous sources, and a prediction on the migration was made, which provide an important basis for the environmental impact assessment of oilfield exploitation project.

The enhanced electrogenerated chemiluminescence of Ru(bpy)3(2+) by glutathione on a glassy carbon electrode modified with some porphine compounds

It has been found that the electrochemical activity of glutathione was increased greatly at the glassy carbon electrodes modified with 5,10,15,20-tetraphenylporphine ruthenium(II) carbenyl (RuTPP), meso-tetraphenylporphine copper(II) complex (CuTTP) and hemin. It has been also found that glutathione would enhance the electrogenerated chemiluminescence (ECL) of Ru(bpy)3(2+) at a hemin glassy carbon electrode; the enhanced ECL intensity was linear with the concentration of glutathione in the range of 1 x 10(-7)-1 x 10(-4) mol l-1, based on which method for determination of glutathione has been developed. The detection limit of glutathione was 2 x 10(-8) mol l-1, and the relative standard deviation for 1 x 10(-6) mol l-1 glutathione was 2.7%. The mechanism for this ECL system has been proposed.

Symbiosis-specific expression of Rhizobium etli casA encoding a secreted calmodulin-related protein

Symbiosis between Rhizobium and its leguminous host requires elaborate communication between the partners throughout the interaction process. A calmodulin-like protein, termed calsymin, was identified in Rhizobium etli; a calmodulin-related protein in a Gram-negative bacterium had not been described previously. Calsymin possesses three repeated homologous domains. Each domain contains two predicted EF-hand Ca(2+)-binding motifs. Ca(2+)-binding activity of calsymin was demonstrated on purified protein. R. etli efficiently secretes calsymin without N-terminal cleavage of the protein. The gene encoding calsymin, casA, is exclusively expressed during colonization and infection of R. etli with the host. Expression of casA is controlled by a repressor protein, termed CasR, belonging to the TetR family of regulatory proteins. Mutation of the casA gene affects the development of bacteroids during symbiosis and symbiotic nitrogen fixation.

Bi-functional gfp- and gusA-containing mini-Tn5 transposon derivatives for combined gene expression and bacterial localization studies

The gfp gene, encoding the green fluorescent protein, was combined with the gusA gene, coding for the beta-glucuronidase enzyme, in mini-Tn5 transposon derivatives for use in Gram-negative bacteria. These mini-Tn5 elements allow simultaneously monitoring of gene expression and localization of the marked bacteria. Introduction of the resultant mini-Tn5 transposons into Rhizobium etli, Azospirillum brasilense and Pseudomonas stutzeri allowed us to visualise the interaction of these bacteria with their host plant. The dual-marker mini-Tn5 transposons constitute a powerful new tool for studying gene expression and ecology of bacteria in the environment and during the interaction with plants.

[The prospective study of the influence of cytomegalovirus (CMV) infection of pregnant women to fetus]

Screening of CMV infection in 450 pregnant women in Shenyang was carried on by ELISA and PCR methods, and CMV infection was detected in 100 of their infants prospectively. The results were 97.11% of pregnant women with past infection, 0.89% with primary infection, 11.11% with recurrent infection, only 2% were susceptible. From 450 pregnant women, there were 3 infants with congenital defects and 3 abortions in active infective group, who were positive for IgM antibody, CMV DNA were positive in heparin peripheral blood, cervical secretion, placenta or amnionic fluid. The fetal infection rate and congenital defect rate in infective group were higher than that in inactive control group. Within 100 maternal-infant pair group, congenitally infected infants were 1.43 times higher in infective group than that in control group (RR = 1.43). Two infants with mental retardations (MDI<70) were born in infective group, but none in control group. In our study, primary infection of early pregnancy was most harmful to fetus, the intrauterine transmission rate was 33.3%. Among nine infected infants born from the infective group, two infants were with CID, and seven were symptomless. CMV screening is important for pregnant women in view of eugenic. When active CMV infection is found in early pregnancy, termination of pregnancy is better considered while CMV detection of amniotic fluid is also positive.