Combinatorial in vivo genome editing identifies widespread epistasis during lung tumorigenesis

Lung adenocarcinoma, the most common subtype of lung cancer, is genomically complex, with tumors containing tens to hundreds of non-synonymous mutations. However, little is understood about how genes interact with each other to enable tumorigenesis in vivo , largely due to a lack of methods for investigating genetic interactions in a high-throughput and multiplexed manner. Here, we employed a novel platform to generate tumors with all pairwise inactivation of ten tumor suppressor genes within an autochthonous mouse model of oncogenic KRAS-driven lung cancer. By quantifying the fitness of tumors with every single and double mutant genotype, we show that most tumor suppressor genetic interactions exhibited negative epistasis, with diminishing returns on tumor fitness. In contrast, Apc inactivation showed positive epistasis with the inactivation of several other genes, including dramatically synergistic effects on tumor fitness in combination with Lkb1 or Nf1 inactivation. This approach has the potential to expand the scope of genetic interactions that may be functionally characterized in vivo , which could lead to a better understanding of how complex tumor genotypes impact each step of carcinogenesis.

Modeling the genomic complexity of human cancer using Cas12a mice

Somatic genome editing in mouse models has increased our understanding of the in vivo effects of genetic alterations in areas ranging from neuroscience to cancer biology and beyond. However, existing models have been restricted in their ability to create multiple targeted edits, which has limited investigations into complex genetic interactions that underlie development, homeostasis, and disease. To accelerate and expand the generation of complex genotypes in somatic cells, we generated transgenic mice with Cre-regulated and constitutive expression of enhanced Acidaminococcus sp. Cas12a (enAsCas12a), an RNA-guided endonuclease with unique attributes that enable simple targeting of multiple genes. In these mice, enAsCas12a-mediated somatic genome editing robustly generated compound genotypes, as exemplified by the initiation of oncogene-negative lung adenocarcinoma, small-cell lung cancer, and a canonical genotype of pancreatic ductal adenocarcinoma, all driven by homozygous inactivation of trios of tumor suppressor genes. We further integrated these modular crRNA arrays with clonal barcoding to quantify the size and number of tumors with each array. These Cas12a alleles will enable the rapid generation of disease models and broadly facilitate the high-throughput investigation of coincident genomic alterations in somatic cells in vivo .

[ Ⅲ ]

Objective: To assess maxillary sagittal and vertical as well as upper airway changes immediately after mini-screw assisted rapid maxillary expansion (MARME) in class Ⅲ patients. Method: A consecutive sample of 48 class Ⅲ patients with maxillary transverse deficiency who visited the Department of Orthodontics, School & Hospital of Stomatology, Wuhan University between January 2013 and March 2023 was retrospectively collected. The sample was comprised of 24 growing patients (cervical vertebra maturation, CVM 1-4) and 24 nongrowing patients (CVM 5-6). Cone-beam CT scans before (T0) and immediately after MARME (T1) were imported into Dolphin Imaging software, and then voxel-based superimposition was conducted on the basis of the anterior cranial base. Sagittal and vertical changes of the maxillary landmarks (A, ANS, PNS, UI and Spr), as well as upper airway changes after MARME were measured on multiplanar reconstruction views. Wilcoxon signed-rank test was employed to analyze the changes after MARME. Mann-Whitney U test was employed to compare the changes between growing and non-growing patients. Results: Some class Ⅲ patients exhibited significant maxillary sagittal and vertical changes immediately after MARME. The amount of changes in midpalatal suture was 4.03 (2.99, 4.87) mm in growing patients, significantly larger than that in non-growing patients [2.27 (1.49, 3.64) mm] (U=3.18, P=0.001). In growing class Ⅲ patients, the forward changes of A, ANS, PNS, UI and Spr were 0.35 (0.06, 0.80), 0.48 (0.11, 0.88), 0.48 (0.13, 0.99), 0.53 (-0.33, 1.04) and 0.40 (0.03, 0.69) mm, respectively. Vertically, the downward changes of A, ANS, PNS, UI and Spr were 1.45 (0.99, 2.13), 1.18 (0.61, 1.95), 1.30 (0.91, 1.96), 1.20 (0.71, 1.83) and 1.30 (0.81, 1.73) mm, respectively. All changes were significantly different from 0 after treatment (P<0.05). In nongrowing patients, PNS moved forward by 0.18 (-0.08, 0.39) mm while other sagittal changes were statistically insignificant (P>0.05); vertically, the downward changes of A, ANS, PNS, UI and Spr were 0.90 (0.51, 1.39), 0.73 (0.41, 1.21), 0.70 (0.55, 1.08), 0.60 (0.36, 1.19) and 0.70 (0.55, 1.23) mm, respectively. Significant immediate increase of the nasopharynx volume and nasal width was obtained in both groups (P<0.05), and the changes of oropharynx volume and minimum cross-sectional area (MCA) presented as statistically insignificant (P>0.05). Conclusions: For growing class Ⅲ patients, besides transverse expansion, significant forward and downward changes of maxilla were obtained immediately after MARME. For non-growing patients, significant downward changes were observed, while sagittal changes were negligible. The nasopharynx volume increased in both growing and nongrowing class Ⅲ patients immediately after MARME, whereas, the changes of oropharynx volume and MCA presented as statistically insignificant.

High-Throughput Identification, Modeling, and Analysis of Cancer Driver Genes In Vivo

The vast number of genomic and molecular alterations in cancer pose a substantial challenge to uncovering the mechanisms of tumorigenesis and identifying therapeutic targets. High-throughput functional genomic methods in genetically engineered mouse models allow for rapid and systematic investigation of cancer driver genes. In this review, we discuss the basic concepts and tools for multiplexed investigation of functionally important cancer genes in vivo using autochthonous cancer models. Furthermore, we highlight emerging technical advances in the field, potential opportunities for future investigation, and outline a vision for integrating multiplexed genetic perturbations with detailed molecular analyses to advance our understanding of the genetic and molecular basis of cancer.

Abstract IA025: Using genetically engineered mouse models to study sarcoma metastasis

Despite aggressive conventional therapy, many patients with high-risk soft-tissue sarcoma develop metastatic disease. To investigate mechanism(s) of sarcoma metastasis, our lab has utilized genetically engineered mouse models. For example, we injected an adenovirus expressing Cre recombinase (adeno-Cre) into the gastrocnemius muscle of LSL-KrasG12D; p53Flox/Flox (KP) mice to initiate high grade undifferentiated pleomorphic sarcomas, and after amputation approximately 40% of the mice develop lung metastasis. Using a genetic approach, we found that miR-182, NEAT-1, and HIF-1a regulate metastasis to the lung. We also performed lineage tracing with complementary fluorescent proteins and CRISPR-generated bar codes to find that lung metastases from KP sarcomas arise from clones with specific gene expression profiles. Although the KP sarcoma model is useful for studying metastasis, one limitation of this model is that there are few non-synonymous mutations to engage the immune system. Therefore, we generated a high mutational load primary mouse model of soft tissue sarcoma by injecting adeno-Cre into the gastrocnemius muscle of p53Flox/Flox mice to delete p53 and also injected 3-methylcholanthrene (MCA) to generate primary p53/MCA undifferentiated pleomorphic sarcomas. In this p53/MCA model, the overall rate of lung metastasis after amputation was surprisingly low (~12%). We hypothesized that the immune system suppressed lung metastasis in this model. However, when we generated p53/MCA sarcomas in Rag2 −/− mice that lack mature B and T cells, we still observed a low rate of lung metastasis after amputation. These data suggest that mutations caused by MCA may have disabled tumor intrinsic factors needed to drive sarcoma metastasis. We are currently performing genome-wide screens in the p53/MCA model to search for genes required for sarcoma metastasis.

Citation Format: David G. Kirsch, Rutulkumar Patel, Sophie R. Finkelstein, Joy Ban, Yuning J Tang, Jianguo Huang, Benjamin A. Alman, Yvonne M. Mowery. Using genetically engineered mouse models to study sarcoma metastasis [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA025.

Abstract 821: Dissecting the role of Stag2 in lung adenocarcinoma

Lung cancer is the most common cause of cancer-related deaths worldwide. Cancers are driven by genomic alterations that activate tumor-promoting oncogenes and inactivate tumor suppressor genes. While some of the most common driver genes have been extensively characterized, many tumor suppressor genes are less well studied. A better understanding of the mechanisms by which different tumor suppressor genes constrain tumorigenesis has the potential to uncover unappreciated biological processes that influence carcinogenesis. Recently, we performed an in vivo screen within a genetically engineered mouse model of oncogenic KRAS-driven lung cancer and found that STAG2 inactivation dramatically increases tumor growth. While STAG2 is mutated in ~4% of human lung adenocarcinomas, 20% of lung adenocarcinomas are low or negative for STAG2 protein. STAG2 is a subunit of one of the two major cohesin complexes, which are present in all cell types and have been implicated in many different cellular processes. STAG2 has not previously been recognized as a critical tumor suppressor in lung cancer and the mechanism through which its inactivation drives lung tumor growth is unknown. Immunohistochemistry, low-pass whole genome sequencing, and analysis of canonical target genes suggest that STAG2 inactivation is not associated with mechanisms previously implicated in other cancer types including chromosomal instability, increased DNA damage, or the activation of MEK/ERK or cGAS/STING signaling. Interesting, we have found that Stag2 is the only cohesin subunit that functions as a tumor suppressor in lung cancer in vivo. Chromatin accessibility profiling and gene expression analyses on Stag2-proficient and -deficient mouse lung adenocarcinoma cells have unveiled potential mediators and effects of STAG2 function. Ongoing genomic analyses of human and mouse lung cancers will demystify the relationship between major cohesin complexes, uncover the impact of STAG2 inactivation on cohesin binding genome wide, and investigate the role of Stag2 inactivation on the tumor microenvironment. We anticipate that our study will uncover the mechanisms of STAG2-mediated tumor suppression in lung cancer and provide novel insights into lung tumorigenesis.

Citation Format: Emily L. Ashkin, Hongchen Cai, Yuning J. Tang, Chuan Li, Su Kit Chew, King Hung, Julia Belk, Saswati Karmakar, Jess Hebert, Maryam Yousefi, Charles Swanton, Dmitri A. Petrov, Monte Winslow. Dissecting the role of Stag2 in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 821.

[Analysis of the relationship between syncope and poor prognosis in patients with acute pulmonary embolism and related factors]

Objective: To explore the association between syncope and poor prognosis and related factors of syncope in patients with acute pulmonary embolism (APE). Methods: A total of 740 patients with first diagnosed APE treated in West China Hospital of Sichuan University from September 1, 2016 to December 30, 2019 were enrolled. The basic information and clinical information (including clinical manifestations, complications, auxiliary examination, treatment and prognosis, etc.) of the patients were obtained from inpatient medical records. The patients were divided into the syncope group and the non-syncope group according to whether they had syncope or not. The basic and clinical conditions of the two groups were compared, and the factors related to syncope in APE patients were analyzed by multiple logistic regression model. Results: The proportion of APE patients with syncope was 12.6% (93/740). Age was (59±16) years in the syncope group (93 cases) and (59±17) years in the non-syncope group (647 cases), with 57.0% (53/93) and 60.4% (391/647) males, respectively. The body mass index, in-hospital mortality, proportions with high risk APE and mechanical ventilation of the syncope group were higher than those of the non-syncope group [(24.5±4.0) kg/m² vs (23.3±3.8) kg/m², 16.1% vs 7.7%, 4.4% vs 1.3% and 9.7% vs 2.5%, respectively]. The length of hospital stay [M (Q₁, Q₃)] of the syncope group was longer than that of the non-syncope group [15 (10, 22) d vs 14 (9, 22) d], and the proportions with chest pain and hemoptysis were lower than those of the non-syncope group (19.4% vs 36.8% and 14.0% vs 27.2%, respectively) (all P values<0.05). Multivariate logistic regression analysis showed that enlargement of the right heart [OR (95%CI): 2.46 (1.07, 5.64)] was a factor associated with syncope in APE patients. Conclusion: The proportion of APE patients with syncope is relatively high and is associated with poor prognosis, while enlargement of the right heart is associated with syncope in APE patients.

Distinct Roles of Glutamine Metabolism in Benign and Malignant Cartilage Tumors With IDH Mutations

Enchondromas and chondrosarcomas are common cartilage neoplasms that are either benign or malignant, respectively. The majority of these tumors harbor mutations in either IDH1 or IDH2. Glutamine metabolism has been implicated as a critical regulator of tumors with IDH mutations. Using genetic and pharmacological approaches, we demonstrated that glutaminase-mediated glutamine metabolism played distinct roles in enchondromas and chondrosarcomas with IDH1 or IDH2 mutations. Glutamine affected cell differentiation and viability in these tumors differently through different downstream metabolites. During murine enchondroma-like lesion development, glutamine-derived α-ketoglutarate promoted hypertrophic chondrocyte differentiation and regulated chondrocyte proliferation. Deletion of glutaminase in chondrocytes with Idh1 mutation increased the number and size of enchondroma-like lesions. In contrast, pharmacological inhibition of glutaminase in chondrosarcoma xenografts reduced overall tumor burden partially because glutamine-derived non-essential amino acids played an important role in preventing cell apoptosis. This study demonstrates that glutamine metabolism plays different roles in tumor initiation and cancer maintenance. Supplementation of α-ketoglutarate and inhibiting GLS may provide a therapeutic approach to suppress enchondroma and chondrosarcoma tumor growth, respectively. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

The Amino Acid Sensor Eif2ak4/GCN2 Is Required for Proliferation of Osteoblast Progenitors in Mice

Skeletal stem/progenitor cells (SSPC) are critical regulators of bone homeostasis by providing a continuous supply of osteoblasts throughout life. In response to inductive signals, SSPC proliferate before osteoblast differentiation. Proliferation requires the duplication of all cellular components before cell division. This imposes a unique biosynthetic requirement for amino acids that can be used for biomass production. Thus, the ability to sense and respond to amino acid availability is likely a major determinant for proliferation. Using a cellular and genetic approach, we demonstrate the amino acid sensor GCN2 is required to support the robust proliferative capacity of SSPC during bone homeostasis. GCN2 ablation results in decreased postnatal bone mass due primarily to reduced osteoblast numbers. Decreased osteoblast numbers is likely attributed to reduced SSPC proliferation as loss of GCN2 specifically affected proliferation in cultured bone marrow stromal cells (BMSCs) without impacting osteoblast differentiation in vitro. Mechanistically, GCN2 regulates proliferation by increasing amino acid uptake downstream of the transcriptional effector ATF4. Collectively, these data suggest amino acid sensing through the GCN2/ATF4 pathway is indispensable for robust SSPC proliferation necessary for bone homeostasis. © 2020 American Society for Bone and Mineral Research.

Tracing Tumor Evolution in Sarcoma Reveals Clonal Origin of Advanced Metastasis

Cellular heterogeneity is frequently observed in cancer, but the biological significance of heterogeneous tumor clones is not well defined. Using multicolor reporters and CRISPR-Cas9 barcoding, we trace clonal dynamics in a mouse model of sarcoma. We show that primary tumor growth is associated with a reduction in clonal heterogeneity. Local recurrence of tumors following surgery or radiation therapy is driven by multiple clones. In contrast, advanced metastasis to the lungs is driven by clonal selection of a single metastatic clone (MC). Using RNA sequencing (RNA-seq) and in vivo assays, we identify candidate suppressors of metastasis, namely, Rasd1, Reck, and Aldh1a2. These genes are downregulated in MCs of the primary tumors prior to the formation of metastases. Overexpression of these suppressors of metastasis impair the ability of sarcoma cells to colonize the lungs. Overall, this study reveals clonal dynamics during each step of tumor progression, from initiation to growth, recurrence, and distant metastasis.

Intracellular cholesterol biosynthesis in enchondroma and chondrosarcoma

Enchondroma and chondrosarcoma are the most common benign and malignant cartilaginous neoplasms. Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) are present in the majority of these tumors. We performed RNA-seq analysis on chondrocytes from Col2a1Cre;Idh1LSL/+ animals and found that genes implied in cholesterol synthesis pathway were significantly upregulated in the mutant chondrocytes. We examined the phenotypic effect of inhibiting intracellular cholesterol biosynthesis on enchondroma formation by conditionally deleting SCAP (sterol regulatory element-binding protein cleavage-activating protein), a protein activating intracellular cholesterol synthesis, in IDH1 mutant mice. We found fewer enchondromas in animals lacking SCAP. Furthermore, in chondrosarcomas, pharmacological inhibition of intracellular cholesterol synthesis significantly reduced chondrosarcoma cell viability in vitro and suppressed tumor growth in vivo. Taken together, these data suggest that intracellular cholesterol synthesis is a potential therapeutic target for enchondromas and chondrosarcomas.

[Comparison of risk factors and short-term and long-term prognosis of pulmonary embolism between the Tibetan and Han people]

Objective: To compare the differences of risk factors and prognosis of pulmonary embolism (PE) between the Tibetans and the Hans. Methods: Patients over 18 years old with confirmed PE and complete clinical data from West China Hospital of Sichuan University from January 2010 to January 2016 were prospectively enrolled and divided into Tibetan group and Han group. Clinical data were collected to compare risk factors and short-term prognosis between Han group and Tibetan group. In addition, a 2-year follow-up was conducted among patients after discharge to investigate the long-term prognosis. Results: A total of 90 patients in Tibetan group and 626 patients in Han group were finally included in this study. Patients in Tibetan group were younger than Han group [(52.2±15.8) vs (59.8±16.6) years old, P<0.001], and the proportion of elderly patients (age ≥70 years) in Tibetan group was significantly lower than that of Han group (15.6% vs 33.7%, P=0.001). The hemoglobin, hematocrit, platelet counts and fibrinogen in Tibetan group were higher than those in Han group [(134.0±32.0) vs (122.2±25.7) g/L, (41.2±9.2)% vs (37.6±7.3)% and (222.2±97.5)×10(9)/L vs (187.5±87.2)×10(9)/L, 3.71(2.51, 4.89) vs 3.31(2.44, 4.42) g/L; P<0.001, <0.001 and P=0.001, 0.048, respectively]. Malignancy and chronic obstructive pulmonary disease were more common in Han group (P=0.011, 0.001), while prior venous thromboembolism history, pregnancy or a history delivery within 1 month were more common in Tibetan group (P=0.041, 0.001). Both short-term and long-term mortality in Tibetan group were significantly lower than that in Han group (2.2% vs 11.5%, 13.6% vs 24.9%; P=0.005, 0.020). Conclusions: Hypercoagulable state plays an important role in the pathogenesis of PE in Tibetan patients. Both short-term and long-term prognosis of PE in Tibetan patients are better than that in Han patients.

[Experience of 14 cases using hemi-semilaminectomy microsurgery treating by spinal dural arteriovenous fistula]

Objective: To explore the efficacy and feasibility of the hemi-semilaminectomy microsurgical operation treatment of spinal dural arteriovenous fistula (SDAVF). Methods: The clinical data of 32 patients with SDAVF were analyzed retrospectively. Before operation all patients were diagnosed by spinal MRI and spinal angiography, 14 patients were treated by hemi-semilaminectomy approach and other 18 patients were by traditional laminectomy approach. All the data were analyzed by T test and P<0.05 was considered to have significant difference. Results: The nidus of SDAVF located on thoracic segments in 18 cases, lumbar segments in 12 cases, and cervical segment in 2 cases, which was fed by single artery. The hemi-semilaminectomy microsurgical operation showed shorter operation time, less bleeding, less hospitalization time and cost. All the patients followed-up for 6 months-2 years. Symptoms of all the patients were improved compared with those before surgery. Conclusions: On the premise of spinal angiography accurately positioning the location of fistula, the hemi-semi-laminectomy approach microsurgery clipping operation is safe and feasible, and the operation has fewer traumas, also helps to maintain the stability of spine.

[Risk factors of pulmonary embolism in senile and non-senile inpatients and the predictive value of Caprini risk assessment model in these two populations]

Objective: To investigate the risk factors of pulmonary embolism (PE) in senile and non-senile inpatients, and evaluate the predictive value of Caprini risk assessment model in these two populations. Methods: Case control study design was used in this study. All the PE patients diagnosed in West China Hospital of Sichuan University between January 2012 and December 2014 was included and divided into senile PE group (age ≥65 years old) and non-senile PE group (age <65 years old). Age matched controls (senile control group and non-senile control group) were selected from the patients admitted into the same departments during the same time period as PE patients, at a ratio of 2∶1. The risk factors of PE for senile and non-senile inpatients were investigated through comparing senile or non-senile PE patients with corresponding controls. All the subjects were retrospectively evaluated by Caprini risk assessment model, and the associations between risk stratifications and PE risk were analyzed. Results: A total of 135 senile PE patients and 212 non-senile PE patients were finally included in this study, with average age of (73.58±6.66) years old and (45.60±13.11) years old, respectively. And 233 age-matched senile controls and 418 non-senile controls were also included. The multivariate analysis showed diabetes (OR=4.08, 95%CI: 1.58-10.51, P=0.004) , heart failure (OR=3.67, 95%CI: 1.10-12.20, P=0.034) , swollen legs (OR=10.50, 95%CI: 5.57-19.79, P<0.001) , severe lung disease (OR=2.05, 95%CI: 1.08-3.90, P=0.028) , patient confined to bed (>72 h) (OR=58.33, 95%CI: 7.46-456.17, P<0.001) were independent risk factors of PE in senile patients, while obesity[body mass index (BMI)≥25 kg/m(2)](OR=2.72, 95%CI: 1.42-5.24, P=0.003), history of deep venous thrombosis (DVT)/PE (OR=17.54, 95%CI: 2.74-112.19, P=0.002) , hip, pelvis, or leg fracture (OR=18.31, 95%CI: 1.97-170.11, P=0.011) , swollen legs (OR=18.53, 95%CI: 11.29-30.40, P<0.001) , severe lung disease ( OR=4.11, 95%CI: 2.41-7.00, P<0.001) , patient confined to bed (>72 h) (OR=4.04, 95%CI: 2.03-8.04, P<0.001) were independent risk factors of PE in non-senile patients. Among the senile patients, the risk of PE increased with the increase of Caprini risk levels; compared with Caprini moderate risk, classifications of high risk and highest risk were associated with 4.64-fold (95%CI: 1.05-20.44, P=0.043) and 10.74-fold (95%CI: 2.46-46.94, P=0.002) increased risk of PE, respectively; within the highest subgroup, the per 2-score increase of Caprini score was associated with 3.02-fold (95%CI: 1.76-5.19, P<0.001) increased risk of PE. Among those non-senile patients, the risk of PE for Caprini low risk and high risk patients was not significantly different, compared with Caprini moderate risk patients; however, the highest risk was still associated with 3.94-fold (95%CI: 2.39-6.51, P<0.001) increased risk of PE compared with moderate risk; within this subgroup, the per 2-score increase of Caprini score was associated with 2.13-fold (95%CI: 1.21-3.73, P=0.008) increased risk of PE. Conclusions: Swollen legs, severe lung disease, confined to bed (>72 h) are common PE risk factors among both senile and non-senile inpatients. Diabetes, heart failure are unique PE risk factors for senile inpatients, while obesity (BMI≥25 kg/m(2)), history of DVT/PE, hip, pelvis, or leg fracture are unique PE risk factors for non-senile inpatients. The Caprini risk assessment model has better predictive value in senile patients than non-senile patients, while Caprini highest risk classification is companied by significantly increased risk of PE in both populations.

Intracellular biosynthesis of lipids and cholesterol by Scap and Insig in mesenchymal cells regulates long bone growth and chondrocyte homeostasis

During enchondral ossification, mesenchymal cells express genes regulating the intracellular biosynthesis of cholesterol and lipids. Here, we have investigated conditional deletion of Scap or of Insig1 and Insig2 (Scap inhibits intracellular biosynthesis and Insig proteins activate intracellular biosynthesis). Mesenchymal condensation and chondrogenesis was disrupted in mice lacking Scap in mesenchymal progenitors, whereas mice lacking the Insig genes in mesenchymal progenitors had short limbs, but normal chondrogenesis. Mice lacking Scap in chondrocytes showed severe dwarfism, with ectopic hypertrophic cells, whereas deletion of Insig genes in chondrocytes caused a mild dwarfism and shortening of the hypertrophic zone. In vitro studies showed that intracellular cholesterol in chondrocytes can derive from exogenous and endogenous sources, but that exogenous sources cannot completely overcome the phenotypic effect of Scap deficiency. Genes encoding cholesterol biosynthetic proteins are regulated by Hedgehog (Hh) signaling, and Hh signaling is also regulated by intracellular cholesterol in chondrocytes, suggesting a feedback loop in chondrocyte differentiation. Precise regulation of intracellular biosynthesis is required for chondrocyte homeostasis and long bone growth, and these data support pharmacological modulation of cholesterol biosynthesis as a therapy for select cartilage pathologies.

Summary: Conditional deletion of genes that regulate intracellular cholesterol biosynthesis in mesenchymal cells or chondrocytes shows that precise regulation of biosynthesis is required for chondrocyte homeostasis and long bone growth.

Expression of inflammatory cytokines in ovarian epithelial cancer and their correlation

This study investigates the expression of interleukin (IL)-17 (IL-17A and IL-17D) and its role in ovarian epithelial tumor and its correlation with the clinical characteristics. Fifty malignant ovarian epithelial tumor specimens were collected after surgery and set as group A. Ten benign epithelioma specimens and ten normal epithelial specimens were set as group B and C, respectively. The expression of IL-17A and IL-17D in the three groups was detected using the EnVision method, and the correlation of positive expression rate with pathological type, clinical stage, presence of ascites and differentiation degree was analyzed. Group A had higher expression of IL-17A and IL-17D compared to group B and C (p less than 0.05). The expression rate was in correlation to clinical stage and differentiation degree, but in no correlation to pathological type and presence of ascites. The expression rate of malignant epithelioma in the early stage was lower than that in the late stage (p less than 0.05). Lower differentiation degree indicated higher expression rate (p less than 0.05). Pathological type and presence of ascites had no remarkable influence on the expression rate (p>0.05). Study of the expression of IL-17 provides theoretical support for the clinical treatment and prognosis prediction of ovarian epithelial tumor.

[Risk factors of venous thromboembolism recurrence and the predictive value of simplified pulmonary embolism severity index in medical inpatients]

OBJECTIVE

To explore the risk factors of venous thromboembolism (VTE) recurrence and the predictive value of simplified pulmonary embolism severity index (sPESI) in medical inpatients.

METHODS

A total of 149 consecutive patients with first diagnosed VTE from the medical departments of West China Hospital of Sichuan University from January 2011 and December 2012 were enrolled and followed-up for 24 months. The VTE recurrence rate was calculated and univariate and multivariate cox proportional hazards regression analysis were performed to identify the risk factors associated with VTE recurrence. All the patients were evaluated by sPESI, and survival analysis was used to explore its value in predicting VTE recurrence in these medical patients.

RESULTS

Out of the included 149 patients, 23(15.4%) patients had VTE recurrence during the 2 years' follow-up and median recurrence time was 167 days. The univariate analysis showed bed rest, severe lung disease, nephrotic syndrome, inappropriate anticoagulant therapy, smoking, diabetes, and malignant neoplasm might be associated with VTE recurrence (P=0.043, 0.006, 0.009, 0.032, 0.098, 0.048, 0.021). Among these risk factors, the multivariate analysis revealed severe lung disease, nephrotic syndrome, and malignant neoplasm were the independent risk factors (HR=3.45, 5.67, 3.60; P=0.020, 0.020, 0.047); while for inappropriate anticoagulant therapy, the P value was marginal (HR=3.94, 95% CI: 0.99-15.63, P=0.051). The median sPESI scores of the patients with VTE recurrence was higher than that of the patients without VTE recurrence[1(1, 2) vs 0(0, 1), P=0.001], and patients with sPESI≥1 were associated with 5.57-fold increased risk of VTE recurrence compared with patients with sPESI=0 (95%CI: 1.79-17.30, P=0.001). Survival analysis also showed that the 2-year cumulative VTE recurrence rate of patients with sPESI≥1 was significant higher than that of patients with sPESI=0 (38.4% vs 5.7%, P=0.001).

CONCLUSIONS

The medical VTE patients have high VTE recurrence risk, and severe lung disease, nephrotic syndrome, malignant neoplasm and inappropriate anticoagulant therapy are important risk factors of VTE recurrence. The sPESI has predictive value for VTE recurrence in medical patients.

Identification of CD146 as a marker enriched for tumor-propagating capacity reveals targetable pathways in primary human sarcoma

Tumor-propagating cells (TPCs) are believed to drive cancer initiation, progression and recurrence. These cells are characterized by enhanced tumorigenicity and self-renewal. The ability to identify such cells in primary human sarcomas relies on the dye exclusion ability of tumor side population (SP) cells. Here, we performed a high-throughput cell surface antigen screen and found that CD146 is enriched in the SP population. In vivo serial transplantation assays showed that CD146+ cells are highly tumorigenic, capable of self-renewal and thus enriches for the TPC population. In addition, depletion of SP cells from the CD146+ population show that CD146+ cells and SP cells are a distinct and overlapping TPC populations. Gene expression profiling of CD146+ and SP cells revealed multiple pathways commonly upregulated in both of these populations. Inhibition of one of these upregulated pathways, Notch signaling, significantly reduced tumor growth and self-renewal. Our data demonstrate that CD146 is an effective cell surface marker for enriching TPCs in primary human sarcomas. Targeting differentially activated pathways in TPCs may provide new therapeutic strategies for treating sarcoma.

Mesenchymal Tumors Can Derive from Ng2/Cspg4-Expressing Pericytes with β-Catenin Modulating the Neoplastic Phenotype

The cell of origin for most mesenchymal tumors is unclear. One cell type that contributes to this lineages is the pericyte, a cell expressing Ng2/Cspg4. Using lineage tracing, we demonstrated that bone and soft tissue sarcomas driven by the deletion of the Trp53 tumor suppressor, or desmoid tumors driven by a mutation in Apc, can derive from cells expressing Ng2/Cspg4. Deletion of the Trp53 tumor suppressor gene in these cells resulted in the bone and soft tissue sarcomas that closely resemble human sarcomas, while stabilizing β-catenin in this same cell type caused desmoid tumors. Comparing expression between Ng2/Cspg4-expressing pericytes lacking Trp53 and sarcomas that arose from deletion of Trp53 showed inhibition of β-catenin signaling in the sarcomas. Activation of β-catenin inhibited the formation and growth of sarcomas. Thus, pericytes can be a cell of origin for mesenchymal tumors, and β-catenin dysregulation plays an important role in the neoplastic phenotype.

[Outcome of childhood T-cell acute lymphoblastic leukemia: a report of 99 cases]

OBJECTIVE

To explore the incidence, clinical characteristics and prognosis of childhood T-cell acute lymphoblastic leukemia (T-ALL) enrolled in protocol ALL-2005.

METHOD

Retrospective reviews of patients diagnosed as having T-ALL were studied in the period between May 2005 and August 2013 in Shanghai Children's Medical Center. Predictive values of early treatment responses, including prednisone response, bone marrow morphology on day 35 during induction chemotherapy, and minimal residual disease (MRD) monitored by flow cytometry on day 35 and 55, were analyzed. The Kaplan-Meier method was used to assess the survival rates.

RESULT

Ninety-nine evaluable patients aged 1-18 years with newly diagnosed T-ALL were enrolled in protocol ALL-2005. The median follow-up period for patients remaining alive in continuous remission was 60 months (24-109 months). The 5-year event free survival (EFS) and overall survival (OS) rates for these patients were 65% and 69%, respectively. Forty-three (43%) patients were older than 10 years at diagnosis. A total of 61 patients presented with initial white blood cell count (WBC)≥50×10(9)/L. Thirty-seven patients with mediastinal mass were found in this study. Seventy-one patients were defined as prednisone good responders (PGR) on day 8 of prednisone therapy. Ninty-four patients achieved complete remission (CR) on day 35 of induction therapy. MRD negative status (<0.01%) on day 35 were seen in 55% of the 42 assessed patients. MRD negative status on day 55 was seen in 78% of the 52 assessed patients. Patients with high MRD (>1%) on day 55 5-year EFS was 40% were associated with poor prognosis (P=0.03). Early T-cell precursor (ETP) subtype was not associated with treatment outcome in this study. Six patients abandoned therapy, 10 lost to follow-up, 22 had relapsed disease, 1 was diagnosed as having a second tumor and 20 patients died.

CONCLUSION

Overall outcome for T-ALL on protocol ALL-2005 is favorable. MRD results on day 55 of induction therapy have important prognostic and therapeutic implications.

ERCC2 rs13181 polymorphism association with glioma susceptibility in a Chinese population

We conducted a case-control study to investigate the role of ERCC2 rs13181 polymorphism in glioma development. A total of 165 patients who were histopathologically diagnosed to have gliomas and 330 controls were collected at Jiujiang First People's Hospital between July 2012 and June 2014. The ERCC2 rs13181 polymorphism was analyzed using a polymerase chain reaction -restriction fragment length polymorphism assay. By conditional regression analysis, we found that the GG genotype of the ERCC2 rs13181 polymorphism is associated with susceptibility to gliomas when compared to the TT genotype (OR = 2.05, 95%CI = 1.11-3.79). In the recessive model, the GG genotype is associated with an increased risk of gliomas when compared with the TT+TG genotype (OR = 1.87, 95%CI = 1.03-3.37). In conclusion, the ERCC2 rs13181 polymorphism is correlated with an increased risk of gliomas in codominant and recessive models, which suggests that this polymorphism could influence the etiology of gliomas.

Influence of Rho kinase inhibitor fasudil on late endothelial progenitor cells in peripheral blood of COPD patients with pulmonary artery hypertension

OBJECTIVE

To investigate the influence of Fasudil, a Rho inhibitor on the number and functions of the late endothelial progenitor cells in peripheral blood of chronic obstructive pulmonary diseases (COPD) patients with pulmonary artery hypertension.

BACKGROUND

It is not clear yet, whether Rho Kinase Inhibitor Fasudil can reduced pulmonary artery pressure through improving lung endothelial function.

METHODS

80 COPD patients with pulmonary artery hypertension were selected and divided into two groups: the treatment group and the control group, which had 40 patients, respectively. Changes in the number and function of the late endothelial progenitor cells in peripheral blood of the patients before and after the treatment were compared between the two groups. The changes on the pulmonary artery pressure were also compared.

RESULTS

The number of the late endothelial progenitor cells in peripheral blood of the treatment group increased and the function was enhanced. The pulmonary artery pressure was reduced. The difference before and after the treatment and with the control group was statistically significant (p < 0.05).

CONCLUSIONS

The Rho-kinase inhibitor Fasudil increased the number and enhanced the function of the late endothelial progenitor cells in peripheral blood of COPD patients with pulmonary artery hypertension (Tab. 3, Fig. 2, Ref. 17).

Inhibitor of signal transducer and activator of transcription 3 (STAT3) suppresses ovarian cancer growth, migration and invasion and enhances the effect of cisplatin in vitro

The aim of the present study was to investigate the anti-ovarian cancer effect of the inhibitor of signal transducer and activator of transcription 3 (STAT3), WP1066. Western blot was used to detect the phosphorylation of STAT3 in ovarian cancer cell line SKOV3 and cisplatin-resistant ovarian cancer cell line SKOV3/DDP. MTT and colony-forming assays were performed to evaluate the viability and growth of ovarian cancer cells. The apoptosis of ovarian cancer cells was determined by flow cytometry. The wound healing assay and Transwell assay were performed to examine the migration and invasion of ovarian cancer cells. WP1066 significantly inhibited the phosphorylation of STAT3 in SKOV3 and SKOV3/DDP cells. WP1066 treatment inhibited the proliferation and clonogenicity of both SKOV3 and SKOV3/DDP cells. After WP1066 treatment for 24 h, the apoptosis rates of SKOV3 and SKOV3/DDP cells were significantly increased compared with the control cells. After treatment with WP1066, the reduction of the wound gaps was significantly less in both SKOV3 and SKOV3/DDP cells. WP1066 also significantly inhibited the invasion capacity of SKOV3 and SKOV3/DDP cells compared with the control group. Treatment with WP1066 combined with cisplatin significantly increased proliferation inhibition and apoptosis in SKOV3 and SKOV3/ DDP cells compared with treatment with cisplatin alone. A synergistic action between WP1066 and cisplatin on the proliferation and apoptosis of ovarian cancer cells was determined. In conclusion, inhibition of STAT3 may suppress the proliferation, migration and invasion, induce apoptosis and enhance the chemosensitivity of ovarian cancer cells, indicating that STAT3 is a new therapeutic target of ovarian cancer.

Fragmentation mechanisms for methane induced by 55 eV, 75 eV, and 100 eV electron impact

The fragmentation of CH4 (2+) dications following 55 eV, 75 eV, and 100 eV electron impact double ionization of methane was studied using a cold target recoil-ion momentum spectroscopy. From the measured momentum of each recoil ion, the momentum of the neutral particles has been deduced and the kinetic energy release distribution for the different fragmentation channels has been obtained. The doubly charged molecular ions break up into three or more fragments in one or two-step processes, resulting in different signatures in the data. We observed the fragmentation of CH4 (2+) dications through different mechanisms according to the momentum of the neutral particles. For example, our result shows that there are three reaction channels to form CH2 (+), H(+), and H, one synchronous concerted reaction channel and two two-step reaction channels. For even more complicated fragmentation processes of CH4 (2+) dications, the fragmentation mechanism can still be identified in the present measurements. The slopes of the peak in the ion-ion coincidence spectra were also estimated here, as they are also related to the fragmentation mechanism.

A novel evaluation index for adolescent idiopathic scoliosis progression measurement and diagnosis

Adolescent idiopathic scoliosis is a trunk deformity of the spine with lateral deviation and rotation in the transverse plane. The most traditional measurement index and parameter for scoliosis diagnosis is the Cobb's angle, which evaluates the curves of the scoliotic spine on the radiographic projection of the trunk. Although this method is widely accepted as the benchmark in scoliosis assessment, it has some limitations and restrictions in practical applications because it is measured on a PA (posterior-anterior or back to front) X-ray image, such as potential harmfulness from radiation exposure and high cost.In this paper, a novel evaluation index for adolescent idiopathic scoliosis measurement and diagnosis is introduced to complement the existing assessment index, such as the Cobb's angle, the differences of shoulder height, etc. The new evaluation index is based on the phenomenon of the tilt and deviation of the vertebras in a scoliotic spine, which forms the tilt angles between each pair of adjacent vertebras.A data sample of 30 X-ray images of scoliotic spines was used in this research to evaluate and examine the usability and validity of the new index. The Cobb's angle and the new index were calculated and compared using the same data sample. The correlation between the Cobb's angle and the index was also determined, and a high correlation is found which demonstrated the usefulness of this proposed index. In this paper, it has been shown that the newly-proposed index has the potential to be used as a tool to support the traditional scoliosis measurement methods.This method can also be generalized on the sagittal plane to define other evaluation indices for assessing the severity of kyphosis and lordosis. The idea of using angular separation to evaluate spinal deformity in multiple planes or in three-dimensional spaces will be discussed in future research.

KiSS1 inhibits growth and invasion of osteosarcoma cells through inhibition of the MAPK pathway

As a metastasis suppressor, KiSS1 has been implicated in numerous human cancers. However, recent studies have demonstrated that KiSS1 promotes tumor growth and metastasis in breast cancer, and it is unclear about the expression and function of KiSS1 in human osteosarcoma (OS). The aim of the present study was to investigate the role and molecular mechanisms of KiSS1 in human OS. The expression of KiSS1 was assessed by immunohistochemical assay using a tissue microarray procedure in forty cases of OS tissues. A gain-of-function approach was used to observe the effects of lentiviral vector-mediated overexpression of KiSS1 (Lv-KiSS1) on the biological behaviors including proliferative activities and invasive potential of OS MG-63 cells, indicated by MTT and Transwell assays, respectively. The results showed that the expression of KiSS1 protein in OS tissues was significantly lowered compared to that in adjacent non-cancerous tissues (ANCT) (42.5% vs 70.0%, P=0.023), and had negative correlation with distant metastases of the tumor (P=0.019). Overexpression of KiSS1 inhibited proliferation and invasion of OS cells with the decreased expression of p38 MAPK and matrix metalloproteinase-9 (MMP-9). Taken together, our findings indicate that the decreased expression of KiSS1 is correlated with distant metastasis of OS, and KiSS1 may function as a tumor suppressor in OS cells through inhibition of the MAPK pathway, suggesting that KiSS1 may serve as a potential therapeutic target for the treatment of cancer.

A new absolute extreme ultraviolet image system designed for studying the radiated power of the Joint Texas Experimental Tokamak discharges

A bolometer imaging system mounted on different toroidal and poloidal locations used for radiation observation has been developed in the Joint Texas Experimental Tokamak (J-TEXT tokamak). Three miniature pinhole AXUV16ELG (16 elements absolute extreme ultraviolet silicon photodiodes) array cameras, which are settled down in the same toroidal position but in three different poloidal places, can provide a broad viewing angle that covers the whole plasma cross-section, and hence can measure the total radiated power and provide the radiated emissive profile, while nine AXUV10EL (10 elements absolute extreme ultraviolet silicon photodiodes) array cameras are divided into three groups and will be mounted on different toroidal locations to observe the toroidal radiated power distribution. Among these detectors, one element of the AXUV16ELG array is absolutely calibrated by the synchrotron radiation source to verify the system reliability. Although there are some discrepancies between the typical responsivity given by IRD Co. and the calibrated results, it is confirmed that the discrepancies have no major effect on the final result after the simulation. The details of the system as well as observations are presented in the paper.

Demonstration of bulk acceleration of ions in ultraintense laser interactions with low-density foams

Ion acceleration inside low-density foams irradiated by ultraintense laser pulses has been studied experimentally and theoretically. It is found that the ion generation is closely correlated with the suppressed hot electron transport inside the foams. Particle-in-cell simulations suggest that localized electrostatic fields with multi peaks around the surfaces of lamellar layers inside the foams are induced. These fields inhibit hot electron transport and meanwhile accelerate ions inside the foams, forming a bulk acceleration in contrast to the surface acceleration at the front and rear sides of a thin solid target.

Structural genomics efforts at the Chinese Academy of Sciences and Peking University

Structural genomics efforts at the Chinese Academy of Sciences and Peking University are reported in this article. The major targets for the structural genomics project are targeted proteins expressed in human hematopoietic stem/progenitor cells, proteins related to blood diseases and other human proteins. Up to now 328 target genes have been constructed in expression vectors. Among them, more than 50% genes have been expressed in Escherichia coli, approximately 25% of the resulting proteins are soluble, and 35 proteins have been purified. Crystallization, data collection and structure determination are continuing. Experiences accumulated during this initial stage are useful for designing and applying high-throughput approaches in structural genomics.

[The development and application of oxypathor of standard atmosphere]

This paper introduces a newly-developed oxypathor under one absolute atmosphere. It provides both oxygen and mixed-oxygen therapies, featuring oxygen-supply and oxygen-inhalation of hyperbaric oxygen chamber, and broaden the clinical applications of oxygen-therapy, which gave shown satisfactory results.

Electroporation of DNA sequences from the pathogenicity locus (PaLoc) of toxigenic Clostridium difficile into a non-toxigenic strain

Toxigenic Clostridium difficile is the etiologic agent of C. difficile-associated diarrhoea (CDAD), the most common cause of hospital-acquired infectious diarrhoea. The genes tcdA and tcdB, which encode for the toxin A and B proteins, are part of the pathogenicity locus (PaLoc) of toxigenic C. difficile. Genetic and virulence studies at the molecular level in C. difficile have been hindered by the lack of techniques for DNA manipulation in this species. We describe the electroporation of DNA fragments from a toxigenic isolate into a non-toxigenic strain of C. difficile. Using previously described methods of electroporation into Clostridium spp., the complete toxin B gene and polymerase chain reaction (PCR) fragments of the PaLoc were cloned and electroporated into a non-toxigenic strain of C. difficile. The resulting transformed clones were screened for the introduced gene fragments by PCR, which confirmed their presence. This is the first description of introduction of DNA into C. difficile by electroporation.

Phosphorus export by runoff from agricultural field plots with different crop cover in Lake Taihu watershed

Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate the effects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m2 for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration for lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m2 for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm2.a) for cropland. Most of P loss is in the PP form, which accounts for more than 90% of TP loss for cropland.

Synthesis, characterization and photodynamic activity of amino-substituted hypocrellin derivatives

Three new hypocrellin derivatives, amino- or amino acid-substituted on the side ring of hypocrellin B (HB), were synthesized by the reactions of HB with 3-methoxypropylamine, 6-aminohexanoic acid and gamma-amino-n-butyric acid, respectively. The structures of these compounds were characterized with proton nuclear magnetic resonance spectra, infrared spectra and mass spectra. The UV-visible absorption spectra, singlet oxygen-generating quantum yield and amphiphilicities of hypocrellin derivatives were measured and compared with HB, the parent compound. These derivatives showed strong absorption in the domain of the phototherapeutic window (600-900 nm) and improved amphiphilicity. HB and the derivatives were preliminarily tested for their photodynamic effects on human oral cavity epithelial carcinoma KB cell line in vitro. Two amino acid-substituted hypocrellins showed phototoxicity to the KB cell line. At an inhibitory dosage of 50% killing only 0.51 mumol L-1 compound 3 (or 0.88 mumol L-1 compound 2) and 0.5 J cm-2 irradiation were required. The hypocrellins exhibited some dark toxicity to the KB cell line. HB and amino acid-substituted hypocrellins showed lower dark toxicity to the KB cell line than amino-substituted hypocrellins in the assessment of cell survival.

Resistance to moxifloxacin in toxigenic Clostridium difficile isolates is associated with mutations in gyrA

Clostridium difficile is the etiological agent of antibiotic-associated colitis and the most common cause of hospital-acquired infectious diarrhea. Fluoroquinolones such as ciprofloxacin are associated with lower risks of C. difficile-associated diarrhea. In this study, we have analyzed 72 C. difficile isolates obtained from patients with different clinical courses of disease, such as toxic megacolon and relapses; the hospital environment; public places; and horses. They were investigated for their susceptibilities to moxifloxacin (MXF), metronidazole (MEO), and vancomycin (VAN). Mutants highly resistant to fluoroquinolones were selected in vitro by stepwise exposure to increasing concentrations of MXF. The resulting mutants were analyzed for the presence of mutations in the quinolone resistance-determining regions of DNA gyrase (gyrA), the production of toxins A and B, and the epidemiological relationship of these isolates. These factors were also investigated using PCR-based methods. All strains tested were susceptible to MEO and VAN. Twenty-six percent of the clinical isolates (19 of 72) were highly resistant to MXF (MIC > or = 16 microg/ml). Fourteen of these 19 strains contained nucleotide changes resulting in amino acid substitutions at position 83 in the gyrA protein. Resistant strains selected in vitro did not contain mutations at that position. These findings indicate that resistance to MXF in a majority of cases may be due to amino acid substitution in the gyrA gene.

Isolation of Clostridium innocuum from cases of recurrent diarrhea in patients with prior Clostridium difficile associated diarrhea

Clostridium innocuum isolates resistant to vancomycin (MIC values of 16-24 microg/mL) were isolated from three patients with recurrent Clostridium difficile -associated diarrhea (CDAD). We discuss the clinical significance and problems associated with the identification and differentiation of these two clostridial species, which may result in misdiagnosis of patients.

[Effects of millimeter wave combined with gamma-ray radiation on human tongue squamous cell carcinoma cell]

OBJECTIVE

To observe the effects of millimeter wave combined with (60)Co gamma-ray radiation on human tongue squamous cell carcinoma cell(Tca8113).

METHODS

Using mm-wave combined with (60)Co gamma-ray to irradiate Tca8113 cell suspensions. The colony forming inhibition efficiency was observed three weeks later. 24 hours after radiation, the samples were observed under electron microscope.

RESULTS

The study showed that the radiation could result in significant decrease of the colony forming efficiency (P<0.001). The inhibition efficiency was higher when the samples were exposed to high power density mm-wave or for a long duration (P<0.05 or P<0.01). The inhibiting effect in combined groups was more obvious than in singly radiated group (P<0.001 or P<0.05). There was no difference between 'R+HL' group and 'HL+R' group (P>0.05). Electron microscopy showed the cells' suprastructures had some injuries and regressive changes. And more serious changes existed in 'H' group.

CONCLUSION

It could be concluded that mm-wave radiation could efficiently inhibit the colony forming capability of Tca8113 cell. And mm-wave radiation could lead to morphological changes of exterior or interior ultrastructures of Tca8113 cell.

Molecular typing methods for the epidemiological identification of Clostridium difficile strains

Toxigenic Clostridium difficile is the etiologic agent of C. difficile-associated diarrhea (CDAD), the most common cause of nosocomial diarrhea. Cross-infection between patients and transmission through the environment and medical personnel are important factors in the acquisition of CDAD. In order to understand differences in epidemiology and pathogenesis, a number of typing schemes have been developed. We will review the typing methods used to study the epidemiology of C. difficile infections and how they have evolved from a phenotypic identification to state of the art molecular methods, detecting genetic polymorphisms among strains. These molecular methods include PCR-based methods (arbitrarily primed-PCR [AP-PCR] and PCR ribotyping), restriction endonuclease analysis (REA) and pulse field gel electrophoresis (PFGE). The application, usefulness and feasibility of these methods are compared and discussed. Finally, the role of genomics as a tool to investigate CDAD is introduced.

Anaerobic bacteria and intrahepatic stones: detections of Clostridium sp. and Bacteroides fragilis

OBJECTIVE

To detect anaerobic bacteria Clostridium sp. and Bacteroides fragilis in intrahepatic stones by molecular genetic method.

METHODS

DNA was extracted from 59 stone samples and subjected to polymerase chain reaction (PCR) amplification targeting the 16S rRNA gene of Clostridium sp. and the glutamine synthetase gene of Bacteroides fragilis. Single-strand conformational polymorphism (SSCP) analysis was performed to identify the Clostridium sp.

RESULTS

16S rRNA gene sequences for Clostridium sp. were identified in 49 stones (83%, 49/59). The two most common groups were detected in 19 (41%) and 17 (37%) of the 46 samples using SSPC analysis, and 25/59 (42%) stones were tested positive for Bacteroides fragilis.

CONCLUSIONS

Anaerobes such as Clostridium sp. and Bacteroides fragilis present in intrahepatic stones and may play a role in stone formation. PCR is a useful technique to detect fastidious pathogens, which are difficult to culture. SSCP of PCR products is a rapid method in differentiating bacterial species.

Genotyping of Bacteroides fragilis isolates from stool specimens by arbitrarily-primed-PCR

In order to determine genetic relatedness of Bacteroides fragilis isolates from different clinical sources, arbitrarily primed polymerase chain reaction (PCR) (AP-PCR) was used to compare 17 strains isolated from patients with inflammatory bowel disease (IBD) and 20 strains isolated from foals with diarrhea. Three reference ATCC strains were also analyzed. Eighteen unique types were identified with a 22-mer arbitrary primer (ERIC-2) among the 20 patient isolates. Types 1 (enterotoxigenic) and 9 (nonenterotoxigenic), were each found in the stools of two patients. All other isolates showed a distinct and unique DNA banding pattern indicating a high degree of genotypic variability. Eleven types were identified among the foal isolates. Type 20, a nonenterotoxigenic type, was present in 30% of the foals. No correlation was found between the human and horse isolates. No clear relationship between a disease state (diarrhea or IBD) and specific types was observed. AP-PCR will be useful as a rapid method to determine genetic relatedness and in future epidemiologic studies of diarrheal diseases due to B. fragilis.

Persistence of an endemic (toxigenic) isolate of Clostridium difficile in the environment of a general medicine ward

The epidemiology of Clostridium difficile-associated diarrhea (CDAD) in an endemic setting was investigated by use of DNA typing methods to determine the strain identity of C. difficile isolates. Two predominant toxigenic clones were found in the environment and accounted for 29.8% (type 1) and 15.5% (type 2) of CDAD cases, respectively. In endemic settings, the environment and cross-transmission may play a role in acquisition of CDAD.

Occurrence of Bacteroides fragilis enterotoxin gene-carrying strains in Germany and the United States

Ninety-three Bacteroides fragilis isolates from different geographic locations were analyzed for the presence of an enterotoxin-encoding gene. It was shown that blood culture isolates were more likely to carry this gene than strains from other sources. All enterotoxin-positive strains belonged to the PCR fingerprint group I.

Isolation and molecular characterization of Clostridium difficile strains from patients and the hospital environment in Belarus

Toxigenic Clostridium difficile is the most common etiologic agent of hospital-acquired diarrhea in developed countries. The role of this pathogen in nosocomial diarrhea in Eastern Europe has not been clearly established. The goal of this study was to determine the prevalence of C. difficile in patients and the hospital environment in Belarus and to characterize these isolates as to the presence of toxin genes and their molecular type. C. difficile was isolated from 9 of 509 (1.8%) patients analyzed and recovered from 28 of 1,300 (2. 1%) environmental sites cultured. A multiplex PCR assay was used to analyze the pathogenicity locus (PaLoc) of all isolates, and strain identity was determined by an arbitrarily primed PCR (AP-PCR). The targeted sequences for all the genes in the PaLoc were amplified in all C. difficile strains examined. A predominantly homogeneous group of strains was found among these isolates, with five major AP-PCR groups being identified. Eighty-three percent of environmental isolates were classified into two groups, while patient isolates grouped into three AP-PCR types, two of which were also found in the hospital environment. Although no data on the role of C. difficile infection or epidemiology of C. difficile-associated diarrhea (CDAD) in this country exist, the isolation of toxigenic C. difficile from the hospital environment suggests that this pathogen may be responsible for cases of diarrhea of undiagnosed origin and validates our effort to further investigate the significance of CDAD in Eastern Europe.

Analysis of the pathogenicity locus in Clostridium difficile strains

The genes for Clostridium difficile toxins A and B (tcdA and tcdB) are part of a 19.6-kb pathogenicity locus (PaLoc) that includes the genes tcdD, tcdE, and tcdC. To determine whether the C. difficile PaLoc is a stable and conserved genetic unit in toxigenic strains, a multiplex polymerase chain reaction was used to analyze 50 toxigenic, 39 nontoxigenic, and 2 toxin-defective isolates. The respective amplicons were identified for tcdA-E in the toxigenic isolates; these were absent in the nontoxigenic isolates. C. difficile P-829 lacked at least a fragment of tcdD, tcdB, tcdE, and tcdC, but tcdA was present. C. difficile 8864 had deletions in the tcdA and tcdC genes. These data suggest that the PaLoc is highly stable in toxigenic C. difficile, nontoxigenic isolates lack the unit, and isolates with a defective PaLoc can still cause clinical disease. Further studies are needed to define the role of individual genes in the pathogenesis of C. difficile-associated diarrhea.

Bacteroides fragilis enterotoxin gene sequences in patients with inflammatory bowel disease

We identified enterotoxigenic Bacteroides fragilis in stool specimens of patients with inflammatory bowel disease and other gastrointestinal disorders. The organism was detected in 11 (13.2%) of 83 patients with inflammatory bowel disease. Of 57 patients with active disease, 19.3% were toxin positive; none of those with inactive disease had specimens positive for enterotoxigenic Bacteroides fragilis gene sequences.

Clostridium difficile: a survey of fecal carriage in cats in a veterinary medical teaching hospital

Fecal samples collected from 245 cats over a 6-month period were analyzed for the presence of Clostridium difficile. After culture on selective media, isolates were identified by a latex agglutination test, and the presence of toxin A and toxin B gene sequences was determined by polymerase chain reaction. Clostridium difficile was isolated from 23 (9.4%) of the cats, and 34.8% of that group were colonized with toxigenic strains. All of the cats colonized with toxigenic C. difficile had > or = 1 of the risk factors (antibiotic use, antineoplastic therapy, immunosuppressive virus infection) associated with C. difficile infection in humans. Clostridium difficile was not found in any of the cats from a clinically healthy outpatient group of cats examined from the same hospital nor in cats from a specific-pathogen-free research colony on the same campus tested during the same time period. The data obtained in this study confirm the presence of C. difficile in cats at a veterinary teaching hospital. DNA fingerprinting analysis of these isolates allowed separation of the strains into 5 groups. Type 4 strain found in 7 cats was also recovered from the floor drain in the same hospital, suggesting a possible source of infection. Whether the organism is of clinical significance in diarrheal diseases of cats remains to be determined.

Detection of Bacteroides fragilis enterotoxin gene by PCR

Bacteroides fragilis constitutes about 1% of the bacterial flora in intestines of normal humans. Enterotoxigenic strains of B. fragilis have been associated with diarrheal diseases in humans and animals. The enterotoxin produced by these isolates induces fluid changes in ligated intestinal loops and an in vitro cytotoxic response in HT-29 cells. We developed a nested PCR to detect the enterotoxin gene of B. fragilis in stool specimens. After DNA extraction, a 367-bp fragment was amplified with two outer primers. The amplicon from this reaction was subjected to a second round of amplification with a set of internal primers. With these inner primers, a 290-bp DNA fragment was obtained which was confirmed as part of the B. fragilis enterotoxin gene by Southern blotting with a nonradioactive internal probe and a chemiluminescence system. By this approach, B. fragilis enterotoxin gene sequences were detected in eight known enterotoxigenic human isolates and nine enterotoxigenic horse isolates. No amplification products were obtained from DNA extracted from 28 nonenterotoxigenic B. fragilis isolates or B. distasonis, B. thetaiotaomicron, B. uniformis, B. ovatus, Escherichia coli, or Clostridium difficile. The sensitivity of this assay allowed us to detect as little as 1 pg of enterotoxin DNA sequences or 100 to 1,000 cells of enterotoxigenic B. fragilis/g of stool. Enterotoxin production of all isolates was confirmed in vitro in HT-29 cells. A 100% correlation was obtained between enterotoxin detection by cytotoxin assay and the nested PCR assay. This rapid and sensitive assay can be used to identify enterotoxigenic B. fragilis and may be used clinically to determine the role of B. fragilis in diarrheal diseases.

Isolation of a toxin B-deficient mutant strain of Clostridium difficile in a case of recurrent C. difficile-associated diarrhea

Clostridium difficile-associated diarrhea (CDAD) recurs in approximately 15%-20% of patients after discontinuation of metronidazole or vancomycin therapy. Most recurrences are believed to be endogenous relapses due to the persistence of spores. However, there is evidence that reinfection with a different strain is a cause of recurrence. We report the case of a patient with a history of multiple episodes of C. difficile colitis. The patient, a 56-year-old female, has had 5 years of repeated recurrences, each shortly after discontinuing vancomycin therapy. During the course of these episodes, three isolates were cultured from her stools at different times. These isolates were analyzed for the presence of toxin A and B gene sequences and genotyped by means of arbitrarily primed polymerase chain reaction (AP-PCR). The original two isolates contained the toxin A and B genes, as determined by PCR, and were of the same AP-PCR type. During her last relapse, a C. difficile strain lacking at least a portion of the toxin B gene was isolated. AP-PCR analysis of this isolate showed a different DNA banding pattern from that of the previous isolates. A vancomycin susceptibility assay revealed a slight decrease in vancomycin activity as compared with that against the prior isolate. This case demonstrates two unique features: (1) recurrent infections can be due to reinfections and (2) toxin B mutants can possibly cause CDAD. This study also raises concerns about long-term vancomycin use and the development of resistance of C. difficile to vancomycin.