Effects of down-regulated carbonic anhydrase 8 on cell survival and glucose metabolism in human colorectal cancer cell lines.

Carbonic anhydrase 8 (CA8) is a member of the α-carbonic anhydrase family but does not catalyze the reversible hydration of carbon dioxide. In the present study, we examined the effects of CA8 on two human colon cancer cell lines, SW480 and SW620, by suppressing CA8 expression through shRNA knockdown. Our results showed that knockdown of CA8 decreased cell growth and cell mobility in SW620 cells, but not in SW480 cells. In addition, downregulated CA8 resulted in a significant decrease of glucose uptake in both SW480 and SW620 cells. Interestingly, stable downregulation of CA8 decreased phosphofructokinase-1 expression but increased glucose transporter 3 (GLUT3) levels in SW620 cells. However, transient downregulation of CA8 fails to up-regulate GLUT3 expression, indicating that the increased GLUT3 observed in SW620-shCA8 cells is a compensatory effect. In addition, the interaction between CA8 and GLUT3 was evidenced by pull-down and IP assays. On the other hand, we showed that metformin, a first-line drug for type II diabetes patients, significantly inhibited cell migration of SW620 cells, depending on the expressions of CA8 and focal adhesion kinase. Taken together, our data demonstrate that when compared to primary colon cancer SW480 cells, metastatic colon cancer SW620 cells respond differently to downregulated CA8, indicating that CA8 in more aggressive cancer cells may play a more important role in controlling cell survival and metformin response. CA8 may affect glucose metabolism- and cell invasion-related molecules in colon cancer, suggesting that CA8 may be a potential target in future cancer therapy.

Can the Blended Application of Controlled-Release and Common Urea Effectively Replace the Common Urea in a Wheat-Maize Rotation System? A Case Study Based on a Long-Term Experiment.

The one-time application of blended urea (BU), combining controlled-release urea (CRU) and uncoated urea, has proven to be a promising nitrogen (N) management strategy. However, the long-term sustainability of blending urea remains largely unexplored. To assess whether a single application of blended urea could effectively replace split uncoated urea applications, a long-term field experiment was conducted in the North China Plain (NCP). The results indicated that, when compared to common urea (CU) at the optimal N rate (180 kg N ha-1), BU achieved comparable grain yields, N uptake and NUE (61% vs. 62). BU exhibited a 12% higher 0-20 cm soil organic nitrogen stock and a 9% higher soil organic carbon (C) stock. Additionally, BU reduced life-cycle reactive N (Nr) losses and the N footprint by 10%, and lowered greenhouse gas (GHG) emissions and the C footprint by 7%. From an economic analysis perspective, BU demonstrated comparable private profitability and a 3% greater ecosystem economic benefit. Therefore, BU under the optimal N rate has the potential to substitute split applications of common urea in the long-term and can be regarded as a sustainable N management strategy for wheat and maize production in the NCP.

Chlamydia repurposes the actin-binding protein EPS8 to disassemble epithelial tight junctions and promote infection.

Invasive microbial pathogens often disrupt epithelial barriers, yet the mechanisms used to dismantle tight junctions are poorly understood. Here, we show that the obligate pathogen Chlamydia trachomatis uses the effector protein TepP to transiently disassemble tight junctions early during infection. TepP alters the tyrosine phosphorylation status of host proteins involved in cytoskeletal regulation, including the filamentous actin-binding protein EPS8. We determined that TepP and EPS8 are necessary and sufficient to remodel tight junctions and that the ensuing disruption of epithelial barrier function promotes secondary invasion events. The genetic deletion of EPS8 renders epithelial cells and endometrial organoids resistant to TepP-mediated tight junction remodeling. Finally, TepP and EPS8 promote infection in murine models of infections, with TepP mutants displaying defects in ascension to the upper genital tract. These findings reveal a non-canonical function of EPS8 in the disassembly of epithelial junctions and an important role for Chlamydia pathogenesis.

[Expert consensus on Antiviral Oral Liquid in treatment of influenza in clinical practice].

Antiviral Oral Liquid is modified on the basis of Baihu Decoction in Treatise on Febrility Diseases by ZHANG Zhongjing and Qingwen Baidu Yin in Qing Dynasty, with effects in clearing toxic heat, repelling dampness and cooling blood. It is widely used in clinical treatment of common colds, influenza and upper respiratory tract infection, mumps, viral conjunctivitis and hand-foot-mouth disease, with a good clinical efficacy and safety. Based on a questionnaire survey of clinicians and a systematic review of study literatures on Antiviral Oral Liquid, the international clinical practice guidelines development method was adopted to analyze the optimal available evidences and expert experiences in the "evidence-based, consensus-based and experience-based" principles. The consensus was jointly reached by more than 30 multidisciplinary experts nationwide, including clinical experts of traditional Chinese and Western medicine in the field of respiratory diseases and infectious diseases, and methodological experts. In the study, literatures were retrieved based on clinical problems in the clinical survey as well as PICO clinical problems. The GRADE system was used for the classification and evaluation of evidence, and fully combined with clinical expert experience, so as to reach expert consensus by the nominal grouping method. This expert consensus recommended or suggested indications, usage and dosage, course of treatment, intervention time for treatment, and the safety and precautions of Antiviral Oral Liquid for treatment of influenza, and can provide reference for the rational use of this drug in clinical practice.

The effectiveness of electro-acupuncture combined with dyclonine hydrochloride in relieving the side effects of gastroscopy: a controlled trial.

BACKGROUND: The present study aimed to explore the effectiveness of electro-acupuncture (EA) in combination with a local anesthetic used in Western medicine in preventing the side effects of gastroscopy. METHODS: A sample group of 150 patients were divided into three groups based on treatment methods: an EA group, a dyclonine hydrochloride mucilage group, and a combined treatment group. In the EA group, EA stimulation was given at the Hegu, Neiguan, and Zusanli acupoints; in the dyclonine hydrochloride mucilage group, patients took 10 mL of dyclonine hydrochloride mucilage orally; in the combined treatment group, prevention of side effects was attempted by administration of both acupuncture and oral local anesthetic. The incidences of nausea, emesis, salivation, cough, restlessness, and breath holding during gastroscopy were observed and recorded for the three groups. Mean arterial pressure, heart rate, and oxygen saturation were recorded before the examination, and changes in these measures were recorded as the gastroscope passed through the pylorus and after the examination. The visual analogue scale (VAS) values of nausea and emesis, the rate of successful first-pass intubation, and the time of gastroscopy were also recorded. Statistical analysis was performed using R-3.5.3 software. RESULTS: Incidences of side effects (e.g., nausea, emesis, salivation, restlessness, and breath holding) during the examination were lower in the combined treatment group than in the EA group and the dyclonine hydrochloride mucilage group (P<0.05 and P<0.01, respectively). Furthermore, the changes in heart rate and oxygen saturation when the gastroscope passed through the pylorus and after the examination were better in the combined treatment group than in the EA group and dyclonine hydrochloride mucilage group (P<0.01). The VAS values of nausea and emesis, the first-pass success rate, and examination duration were also better for the combined treatment group than for the other two groups (P<0.05 and P<0.01). CONCLUSIONS: EA combined with local anesthesia with dyclonine hydrochloride mucilage can alleviate side effects during gastroscopy, reduce patient pain, and improve the efficiency of the procedure.

Application of a C. trachomatis expression system to identify C. pneumoniae proteins translocated into host cells.

Chlamydia pneumoniae is a Gram-negative, obligate intracellular pathogen that causes community-acquired respiratory infections. C. pneumoniae uses a cell contact-dependent type-III secretion (T3S) system to translocate pathogen effector proteins that manipulate host cellular functions. While several C. pneumoniae T3S effectors have been proposed, few have been experimentally confirmed in Chlamydia In this study, we expressed 382 C. pneumoniae genes in C. trachomatis as fusion proteins to an epitope tag derived from glycogen synthase kinase 3ß (GSK3ß) which is the target of phosphorylation by mammalian kinases. Based on the detection of the tagged C. pneumoniae protein with anti-phospho GSK3ß antibodies, we identified 49 novel C. pneumoniae-specific proteins that are translocated by C. trachomatis into the host cytoplasm and thus likely play a role as modifiers of host cellular functions. In this manner, we identified and characterized a new C. pneumoniae effector CPj0678 that recruits the host cell protein PACSIN2 to the plasma membrane. These findings indicate that C. trachomatis provides a powerful screening system to detect candidate effector proteins encoded by other pathogenic and endosymbiotic Chlamydia species.Importance Chlamydia injects numerous effector proteins into host cells to manipulate cellular functions important for bacterial survival. Based on findings in C. trachomatis, it has been proposed that between 5-10% of the C. pneumoniae genome, a related respiratory pathogen, encodes secreted effectors. However only a few C. pneumoniae effectors have been identified and experimentally validated. With the development of methods for the stable genetic transformation of C. trachomatis, it is now possible to use C. trachomatis shuttle plasmids to express and explore the function of proteins from other Chlamydia in a more relevant bacterial system. In this study, we experimentally determined that 49 C. pneumoniae-specific proteins are translocated into the host cytoplasm by Chlamydia secretion systems, and identify a novel effector required to recruit the host factor PACSIN2 to the plasma membrane during infection.

[Systematic review and Meta-analysis of safety of Sanfu acupoint herbal patching in randomized controlled trial].

In order to systematically evaluate the safety of Sanfu acupoint herbal patching, CNKI, SinoMed, VIP, Wanfang, PubMed, Medline, EMbase, and Cochrane Library were searched in accordance with PICOS principles, with a time limit from database establishment to December 2019. Meta-analysis was used for a single-group rate analysis and a weighted combination of these two groups on rates of adverse reactions. A total of 9 articles meeting the inclusion criteria were included in the analysis, involving 2 119 patients. The single-group rate Meta-analysis showed that the adverse reactions incidence was 9% in the treatment group(OR=0.10,95%CI[0.06, 0.19], P<0.000 01), and 9% in the control group(OR=0.10, 95%CI[0.07, 0.13], P<0.000 01). In combined statistics of all samples OR=1.81, 95%CI[1.04, 3.15], P=0.04, the incidence of adverse reactions in the treatment group was slightly higher than that of the control group. In the subgroup analysis, the incidence of adverse reactions in terms of both single-group rate and weighed rate in the treatment group was higher than that in the control group in the asthma subgroup, rhinitis subgroup, ≥18 years old subgroup, and application time 2 h subgroup, with statistically significant differences(P<0.05). The results of the Meta-analysis and systematic review suggested that the incidence of adverse reactions in clinical use of the Sanfu acupoints herbal patching was relatively low. The main types of adverse reactions were skin ulcers, blisters and other skin symptoms. The symptoms were relatively mild, which could be relieved by drug withdrawal or symptomatic treatment. It shows that the safety of the Sanfu acupoint herbal patching was relatively high, and the occurrence of adverse reactions was related to the original disease and age, mainly in asthma and rhinitis or patients over 40 years old. Affected by clinical heterogeneity, the conclusions of the application time subgroup need to be further improved.

CRISPR-Cas9 Gene Editing for Sickle Cell Disease and ß-Thalassemia.

Transfusion-dependent ß-thalassemia (TDT) and sickle cell disease (SCD) are severe monogenic diseases with severe and potentially life-threatening manifestations. BCL11A is a transcription factor that represses γ-globin expression and fetal hemoglobin in erythroid cells. We performed electroporation of CD34+ hematopoietic stem and progenitor cells obtained from healthy donors, with CRISPR-Cas9 targeting the BCL11A erythroid-specific enhancer. Approximately 80% of the alleles at this locus were modified, with no evidence of off-target editing. After undergoing myeloablation, two patients - one with TDT and the other with SCD - received autologous CD34+ cells edited with CRISPR-Cas9 targeting the same BCL11A enhancer. More than a year later, both patients had high levels of allelic editing in bone marrow and blood, increases in fetal hemoglobin that were distributed pancellularly, transfusion independence, and (in the patient with SCD) elimination of vaso-occlusive episodes. (Funded by CRISPR Therapeutics and Vertex Pharmaceuticals; ClinicalTrials.gov numbers, NCT03655678 for CLIMB THAL-111 and NCT03745287 for CLIMB SCD-121.).

In-depth mining of clinical data: the construction of clinical prediction model with R.

This article is the series of methodology of clinical prediction model construction (total 16 sections of this methodology series). The first section mainly introduces the concept, current application status, construction methods and processes, classification of clinical prediction models, and the necessary conditions for conducting such researches and the problems currently faced. The second episode of these series mainly concentrates on the screening method in multivariate regression analysis. The third section mainly introduces the construction method of prediction models based on Logistic regression and Nomogram drawing. The fourth episode mainly concentrates on Cox proportional hazards regression model and Nomogram drawing. The fifth Section of the series mainly introduces the calculation method of C-Statistics in the logistic regression model. The sixth section mainly introduces two common calculation methods for C-Index in Cox regression based on R. The seventh section focuses on the principle and calculation methods of Net Reclassification Index (NRI) using R. The eighth section focuses on the principle and calculation methods of IDI (Integrated Discrimination Index) using R. The ninth section continues to explore the evaluation method of clinical utility after predictive model construction: Decision Curve Analysis. The tenth section is a supplement to the previous section and mainly introduces the Decision Curve Analysis of survival outcome data. The eleventh section mainly discusses the external validation method of Logistic regression model. The twelfth mainly discusses the in-depth evaluation of Cox regression model based on R, including calculating the concordance index of discrimination (C-index) in the validation data set and drawing the calibration curve. The thirteenth section mainly introduces how to deal with the survival data outcome using competitive risk model with R. The fourteenth section mainly introduces how to draw the nomogram of the competitive risk model with R. The fifteenth section of the series mainly discusses the identification of outliers and the interpolation of missing values. The sixteenth section of the series mainly introduced the advanced variable selection methods in linear model, such as Ridge regression and LASSO regression.

[Interpretation and prospect of clinical practice guideline on traditional Chinese medicine therapy alone or combined with antibiotics for sepsis].

Clinical practice guideline on traditional Chinese medicine therapy alone or combined with antibiotics for sepsis is strictly in accordance with the latest diagnostic criteria for sepsis (sepsis-3) for the treatment of septic patients at different stages through syndrome differentiation. At present, the abuse of antibiotics and the prevalence of drug-resistant bacteria are very serious, without effective solutions. Thus, this is the first time to focus on traditional Chinese medicine combined with antibiotics to treat sepsis, in order to minimize the incidence of drug-resistant bacteria. This Guideline tends to systematically analyze the sepsis period, septic shock period as well as different clinical symptoms and traditional Chinese medicine measures for organ dysfunction in the sepsis process. By analyzing and interpreting the Guideline systematically, the clinicians could understand its purpose, significance and core ideas more thoroughly, and grasp the recommended specific interventions as well as their advantages and disadvantages, hoping to better implement the Guideline, provide guidance to clinicians and standardize the treatment of sepsis by traditional Chinese medicine.

[Clinical application evaluation and revision suggestions of clinical practice guideline on traditional Chinese medicine therapy alone or combined with antibiotics for sepsis].

To investigate the clinical application of clinical practice guideline on traditional Chinese medicine therapy alone or combined with antibiotics for sepsis, in order to promote the follow-up revision and further promotion of the Guidelines. Copies of 500 application evaluation questionnaire and 500 copies of applicability evaluation questionnaire were given to the clinicians who had used this Guideline in China, both in a form of registered questionnaire, and a database was established by Excel 2016 for descriptive statistical analysis. Copies of 211 application evaluation questionnaire and 211 copies of applicability evaluation questionnaire were collected. We can conclude from the survey that we should adjust the whole content and structure on the basis of better evaluation of the present recommendation scheme, update the prescription selection and clinical evidence of the recommendation scheme, and put forward the improvement measures for the hindrance factors in the application of the Guideline. Furthermore, in order to promote the Guideline more clearly, we should strengthen the doctor-patient education, improve guidance quality and increase the publicity, providing basis for the implementation and promotion strategies of the Guideline.

The Effector TepP Mediates Recruitment and Activation of Phosphoinositide 3-Kinase on Early Chlamydia trachomatis Vacuoles.

Chlamydia trachomatis delivers multiple type 3 secreted effector proteins to host epithelial cells to manipulate cytoskeletal functions, membrane dynamics, and signaling pathways. TepP is the most abundant effector protein secreted early in infection, but its molecular function is poorly understood. In this report, we provide evidence that TepP is important for bacterial replication in cervical epithelial cells, activation of type I IFN genes, and recruitment of class I phosphoinositide 3-kinases (PI3K) and signaling adaptor protein CrkL to nascent pathogen-containing vacuoles (inclusions). We also show that TepP is a target of tyrosine phosphorylation by Src kinases but that these modifications do not appear to influence the recruitment of PI3K or CrkL. The translocation of TepP correlated with an increase in the intracellular pools of phosphoinositide-(3,4,5)-triphosphate but not the activation of the prosurvival kinase Akt, suggesting that TepP-mediated activation of PI3K is spatially restricted to early inclusions. Furthermore, we linked PI3K activity to the dampening of transcription of type I interferon (IFN)-induced genes early in infection. Overall, these findings indicate that TepP can modulate cell signaling and, potentially, membrane trafficking events by spatially restricted activation of PI3K. IMPORTANCE This article shows that Chlamydia recruits PI3K, an enzyme important for host cell survival and internal membrane functions, to the pathogens inside cells by secreting a scaffolding protein called TepP. TepP enhances Chlamydia replication and dampens the activation of immune responses.

Chlamydia trachomatis Infection Leads to Defined Alterations to the Lipid Droplet Proteome in Epithelial Cells.

The obligate intracellular bacterium Chlamydia trachomatis is a major human pathogen and a main cause of genital and ocular diseases. During its intracellular cycle, C. trachomatis replicates inside a membrane-bound vacuole termed an "inclusion". Acquisition of lipids (and other nutrients) from the host cell is a critical step in chlamydial replication. Lipid droplets (LD) are ubiquitous, ER-derived neutral lipid-rich storage organelles surrounded by a phospholipids monolayer and associated proteins. Previous studies have shown that LDs accumulate at the periphery of, and eventually translocate into, the chlamydial inclusion. These observations point out to Chlamydia-mediated manipulation of LDs in infected cells, which may impact the function and thereby the protein composition of these organelles. By means of a label-free quantitative mass spectrometry approach we found that the LD proteome is modified in the context of C. trachomatis infection. We determined that LDs isolated from C. trachomatis-infected cells were enriched in proteins related to lipid metabolism, biosynthesis and LD-specific functions. Interestingly, consistent with the observation that LDs intimately associate with the inclusion, a subset of inclusion membrane proteins co-purified with LD protein extracts. Finally, genetic ablation of LDs negatively affected generation of C. trachomatis infectious progeny, consistent with a role for LD biogenesis in optimal chlamydial growth.

Trends of cost and mortality of patients on haemodialysis with end stage renal disease.

AIM: The prevalence of end-stage renal disease in Taiwan is among the highest in the world. Treatment reimbursement for haemodialysis was capped in 1996 in order to contain costs. This study evaluated temporal changes in the costs and utilization of medical care and mortality in patients receiving haemodialysis following capped reimbursement. METHODS: Using insurance claims data in Taiwan between 1998 to 2009, we established eight annual subcohorts of patients with incident haemodialysis, increasing from 6099 in 1998 to 7745 in 2005. With a 4-year follow-up paradigm for each subcohort, we evaluated resources use and costs of medical services, as well as mortality trends. RESULTS: The annual mean cost for each haemodialysis patient increased from US $431 to $737 for emergency visits, US $9007 to $13,280 for hospitalizations and US $79,141 to $92,416 (16.8% increase) for total costs, from the initial to final subcohorts, respectively. Compared to the 1998 subcohort, the adjusted hazard ratio of deaths declined from 0.97 (95% CI 0.91 to 1.02) for the 1999 subcohort to 0.86 (95% CI 0.82 to 0.91) for the 2005 subcohort (P for trend <0.001). The corresponding cumulative probability of deaths decreased from 45.5% to 35.4%. CONCLUSIONS: The mortality for patients with haemodialysis decreased annually, whereas the overall annual cost increased despite capped reimbursement for haemodialysis. These results encourage further study on reasons of increased uses of emergency service and hospitalization.

The Chlamydia trachomatis type III secretion chaperone Slc1 engages multiple early effectors, including TepP, a tyrosine-phosphorylated protein required for the recruitment of CrkI-II to nascent inclusions and innate immune signaling.

Chlamydia trachomatis, the causative agent of trachoma and sexually transmitted infections, employs a type III secretion (T3S) system to deliver effector proteins into host epithelial cells to establish a replicative vacuole. Aside from the phosphoprotein TARP, a Chlamydia effector that promotes actin re-arrangements, very few factors mediating bacterial entry and early inclusion establishment have been characterized. Like many T3S effectors, TARP requires a chaperone (Slc1) for efficient translocation into host cells. In this study, we defined proteins that associate with Slc1 in invasive C. trachomatis elementary bodies (EB) by immunoprecipitation coupled with mass spectrometry. We identified Ct875, a new Slc1 client protein and T3S effector, which we renamed TepP (Translocated early phosphoprotein). We provide evidence that T3S effectors form large molecular weight complexes with Scl1 in vitro and that Slc1 enhances their T3S-dependent secretion in a heterologous Yersinia T3S system. We demonstrate that TepP is translocated early during bacterial entry into epithelial cells and is phosphorylated at tyrosine residues by host kinases. However, TepP phosphorylation occurs later than TARP, which together with the finding that Slc1 preferentially engages TARP in EBs leads us to postulate that these effectors are translocated into the host cell at different stages during C. trachomatis invasion. TepP co-immunoprecipitated with the scaffolding proteins CrkI-II during infection and Crk was recruited to EBs at entry sites where it remained associated with nascent inclusions. Importantly, C. trachomatis mutants lacking TepP failed to recruit CrkI-II to inclusions, providing genetic confirmation of a direct role for this effector in the recruitment of a host factor. Finally, endocervical epithelial cells infected with a tepP mutant showed altered expression of a subset of genes associated with innate immune responses. We propose a model wherein TepP acts downstream of TARP to recruit scaffolding proteins at entry sites to initiate and amplify signaling cascades important for the regulation of innate immune responses to Chlamydia.

Coumarins from roots of Clausena excavata.

Two new coumarins, clauexcavatins A (1) and B (2), along with seven known ones (3-9), were isolated from the roots of Clausena excavata Burm. f. (Rutaceae). Their structures were elucidated on the basis of spectral data.

Quantitative proteomics reveals metabolic and pathogenic properties of Chlamydia trachomatis developmental forms.

Chlamydia trachomatis is an obligate intracellular pathogen responsible for ocular and genital infections of significant public health importance. C. trachomatis undergoes a biphasic developmental cycle alternating between two distinct forms: the infectious elementary body (EB), and the replicative but non-infectious reticulate body (RB). The molecular basis for these developmental transitions and the metabolic properties of the EB and RB forms are poorly understood as these bacteria have traditionally been difficult to manipulate through classical genetic approaches. Using two-dimensional liquid chromatography - tandem mass spectrometry (LC/LC-MS/MS) we performed a large-scale, label-free quantitative proteomic analysis of C. trachomatis LGV-L2 EB and RB forms. Additionally, we carried out LC-MS/MS to analyse the membranes of the pathogen-containing vacuole ('inclusion'). We developed a label-free quantification approaches to measure protein abundance in a mixed-proteome background which we applied for EB and RB quantitative analysis. In this manner, we catalogued the relative distribution of > 54% of the predicted proteins in the C. trachomatis LGV-L2 proteome. Proteins required for central metabolism and glucose catabolism were predominant in the EB, whereas proteins associated with protein synthesis, ATP generation and nutrient transport were more abundant in the RB. These findings suggest that the EB is primed for a burst in metabolic activity upon entry, whereas the RB form is geared towards nutrient utilization, a rapid increase in cellular mass, and securing the resources for an impending transition back to the EB form. The most revealing difference between the two forms was the relative deficiency of cytoplasmic factors required for efficient type III secretion (T3S) in the RB stage at 18 h post infection, suggesting a reduced T3S capacity or a low frequency of active T3S apparatus assembled on a 'per organism' basis. Our results show that EB and RB proteomes are streamlined to fulfil their predicted biological functions: maximum infectivity for EBs and replicative capacity for RBs.

Thermodynamic and kinetic consequences of substituting glycine at different positions in a Pro-Hyp-Gly repeat collagen model peptide.

A glycine occurs at every third residue in the X-Y-Gly repeat of natural collagen. Replacing Gly residues destabilizes collagen and is often associated with many diseases. We present a comprehensive study on the thermodynamic and kinetic consequences of replacing Gly residues at different sites in collagen. For this, we prepared a series of peptides that contain a single substitution of Gly with L-Ala, D-Ala, ß-Ala, or sarcosine (Sar), at different positions in a host peptide (Pro-Hyp-Gly)(8) . Circular dichroism measurements showed that peptides with the mutation site near the C-terminus (C-terminal mutations) form a more stable collagen triple helix than those with the substitution near the N-terminus (N-terminal mutations), which is consistent with the known in vivo folding mechanism of collagen, from the C to the N-terminus. Thermodynamic analysis indicated that the destabilization in C-terminal mutations is due to entropic effects, while that in N-terminal mutations is mainly from enthalpic effects. The destabilization order is L-Ala < Sar < ß-Ala < D-Ala substitution in both the N and C-terminal mutations, suggesting that residues with normal torsion angles are less destabilizing at either position. Moreover, Sar was shown to be a better substituent than the other three amino acids at the central site of collagen strands. Kinetic studies further demonstrated that steric strains imposed by the side chains may be the most critical factor affecting the folding rate of collagen. Our data provide valuable insights into how backbone conformation, side chains, and interstrand hydrogen bonds affect the collagen triple helix at different positions.

Tropical pyomyositis caused by salmonella within the gluteus maximus of a hepatitis B carrier.

Tropical pyomyositis, a disease often seen in tropical countries, is characterized by suppuration within the skeletal muscles, manifesting as single or multiple abscesses. Staphylococcus aureus is the most common agent responsible for typical pyomyositis. Misdiagnosis usually occurs as a result of nonspecific presentation, unfamiliarity with the disease, and the many possible differential diagnoses. Here we present a rare case of tropical pyomyositis caused by Salmonella (group D non-typhi Salmonella) within the gluteus maximus of a hepatitis B carrier without definite previous gastrointestinal episodes.

The Chlamydia type III secretion system C-ring engages a chaperone-effector protein complex.

In Gram-negative bacterial pathogens, specialized chaperones bind to secreted effector proteins and maintain them in a partially unfolded form competent for translocation by type III secretion systems/injectisomes. How diverse sets of effector-chaperone complexes are recognized by injectisomes is unclear. Here we describe a new mechanism of effector-chaperone recognition by the Chlamydia injectisome, a unique and ancestral line of these evolutionarily conserved secretion systems. By yeast two-hybrid analysis we identified networks of Chlamydia-specific proteins that interacted with the basal structure of the injectisome, including two hubs of protein-protein interactions that linked known secreted effector proteins to CdsQ, the putative cytoplasmic C-ring component of the secretion apparatus. One of these protein-interaction hubs is defined by Ct260/Mcsc (Multiple cargo secretion chaperone). Mcsc binds to and stabilizes at least two secreted hydrophobic proteins, Cap1 and Ct618, that localize to the membrane of the pathogenic vacuole ("inclusion"). The resulting complexes bind to CdsQ, suggesting that in Chlamydia, the C-ring of the injectisome mediates the recognition of a subset of inclusion membrane proteins in complex with their chaperone. The selective recognition of inclusion membrane proteins by chaperones may provide a mechanism to co-ordinate the translocation of subsets of inclusion membrane proteins at different stages in infection.