[Analysis of the effects and influencing factors of thymectomy for myasthenia gravis].

Objective: To explore the effects of surgical treatment for myasthenia gravis as well as its influencing factors. Methods: A total of 180 patients with myasthenia gravis who underwent thymectomy from August 2012 to September 2018 were enrolled. Clinical data such as age, gender, disease classification, preoperative AChR-Ab, preoperative course, operation time, intraoperative blood loss, and pathological type was retrospectively reviewed. Univariate analysis and Cox regression model were used to analyze possible influencing factors of surgical effects. Results: A total of 145 patients were finally enrolled and the follow-up period was from 4 to 78 months, with a median follow-up time of 34 months. Thirty-four patients (23.4%) achieved complete stable remission (CSR). The total clinical remission and effective rate reached 75.1% (109 cases) and 89.6% (130 cases), respectively. Correlation analysis showed that age below 45 years old, preoperative course within 12 months, positive AChR-Ab and thymic hyperplasia were clinical influencing factors for better surgical results (P=0.030, 0.048, 0.019 and 0.042, respectively). Conclusions: It is safe and effective to undergo thymectomy for myasthenia gravis. Age, preoperative course, AChR-Ab level and pathological type were the influencing factors of surgical effects.

[Factors influencing survival of patients with pancreatic adenocarcinoma after surgical resection].

Objective: To investigate the clinical outcomes and prognostic factors in patients with pancreatic cancer after surgical resection with curative intent and analyze factors affecting 2-year and 5-year survival of patients. Methods: A total of 469 patients with pancreatic adenocarcinoma undergoing curative resection were included in the study, and the clinical data of these patients were analyzed retrospectively. Univariate and multivariate analyses were performed to examine factors affecting prognosis of these patients. The clinicopathological characteristics of patients who survived for ≤2 years and >2 years as well as ≤5 years and >5 years were compared, respectively. Results: The multivariate analysis showed that lymphovascular invasion (P=0.024), lymph node metastasis (P<0.001), vascular resection (P=0.002), maximum tumor diameter >2 cm (P=0.009), poor differentiation (P<0.001) were negative prognosis factors, but postoperative chemotherapy (P<0.001) was an independent positive prognostic factor. Comparison of the patients who survived for ≤2 years and >2 years showed that lymphovascular invasion (P=0.012), lymph node metastasis (P<0.001), vascular resection (P=0.014), maximum tumor diameter>2 cm (P=0.004), poor differentiation (P<0.001), peri-pancreatic fat invasion (P=0.005), absence of postoperative chemotherapy (P<0.001), advanced tumour, node and metastasis (TNM stage) (P<0.001) were associated with 2-year survival. With regard to 5-year survival, lymph node metastasis (P=0.005), poor differentiation (P=0.014) and TNM stage(P=0.025) were associated with it. Conclusions: Our results suggest that lymphovascular invasion, lymph node metastasis, vascular resection, maximum tumor diameter >2 cm, poor differentiation and absence of postoperative chemotherapy were independent negative prognostic factors. Lymph vascular invasion, lymph node metastasis, vascular resection, maximum tumor diameter >2 cm, poor differentiation, peri-pancreatic fat invasion, absence of postoperative chemotherapy, advanced TNM stage were associated with 2-year survival, and lymph node metastasis, degree of differentiation and TNM stage are important prognosis factors affecting long-term survival of patients.

Automatic methods for alveolar bone loss degree measurement in periodontitis periapical radiographs.

BACKGROUND AND OBJECTIVE: Periodontitis involves progressive loss of alveolar bone around the teeth. Hence, automatic alveolar bone loss measurement in periapical radiographs can assist dentists in diagnosing such disease. In this paper, we propose an automatic length-based alveolar bone loss measurement system with emphasis on a cementoenamel junction (CEJ) localization method: CEJ_LG. METHOD: The bone loss measurement system first adopts the methods TSLS and ABLifBm, which we presented previously, to extract teeth contours and bone loss areas from periodontitis radiograph images. It then applies the proposed methods to locate the positions of CEJ, alveolar crest (ALC), and apex of tooth root (APEX), respectively. Finally the system computes the ratio of the distance between the positions of CEJ and ALC to the distance between the positions of CEJ and APEX as the degree of bone loss for that tooth. The method CEJ_LG first obtains the gradient of the tooth image then detects the border between the lower enamel and dentin (EDB) from the gradient image. Finally, the method identifies a point on the tooth contour that is horizontally closest to the EDB. RESULTS: Experimental results on 18 tooth images segmented from 12 periodontitis periapical radiographs, including 8 views of upper-jaw teeth and 10 views of lower-jaw teeth, show that 53% of the localized CEJs are within 3 pixels deviation (∼ 0.15 mm) from the positions marked by dentists and 90% have deviation less than 9 pixels (∼ 0.44 mm). For degree of alveolar bone loss, more than half of the measurements using our system have deviation less than 10% from the ground truth, and all measurements using our system are within 25% deviation from the ground truth. CONCLUSION: Our results suggest that the proposed automatic system can effectively estimate degree of horizontal alveolar bone loss in periodontitis radiograph images. We believe that our proposed system, if implemented in routine clinical practice, can serve as a valuable tool for early and accurate diagnosis of alveolar bone loss in periodontal diseases and also for assessing the status of alveolar bone following various types of non surgical and surgical and regenerative therapy. For overall system improvement, a more objective comparison by using transgingival bone measurement with a periodontal probe as the ground truth and enhancing the localization algorithms of these three critical points are the two major tasks.

Paclitacxel and carboplatin in advanced non-small-cell lung cancer.

To evaluate the efficacy and toxicity of the combination of paclitacxel and carboplatin on advanced non-small-cell lung cancer (NSCLC). Forty-eight patients with locally advanced (stage IIIb) or metastatic (stage IV) NSCLC were enrolled into the study. The patients received paclitacxel 55-60 mg/m(2) on day 1, 8, 15, carboplatin at an AUC of 5 on day 1, administreted in 28-day cycle. An objective response was obtained in 37.5% of patients (two complete and 16 partial responses). Significant difference existed between the naive patients and pretreated patients (46.4% vs. 25.0%, P<0.05). The main toxicities were bone marrow suppression, nausea/vomiting and alopecia. The combination of paclitacxel and carboplatin is an effective, well-tolerated scheme in the treatment of advanced NSCLC. The efficacy is higher in the naive group than in the pretreated group.

Alveolar bone-loss area localization in periodontitis radiographs based on threshold segmentation with a hybrid feature fused of intensity and the H-value of fractional Brownian motion model.

BACKGROUND AND OBJECTIVE: Periodontitis involves progressive loss of alveolar bone around the teeth. Hence, automatic alveolar bone-loss (ABL) measurement in periapical radiographs can assist dentists in diagnosing such disease. In this paper, we propose an effective method for ABL area localization and denote it as ABLIfBm. METHOD: ABLIfBm is a threshold segmentation method that uses a hybrid feature fused of both intensity and texture measured by the H-value of fractional Brownian motion (fBm) model, where the H-value is the Hurst coefficient in the expectation function of a fBm curve (intensity change) and is directly related to the value of fractal dimension. Adopting leave-one-out cross validation training and testing mechanism, ABLIfBm trains weights for both features using Bayesian classifier and transforms the radiograph image into a feature image obtained from a weighted average of both features. Finally, by Otsu's thresholding, it segments the feature image into normal and bone-loss regions. RESULTS: Experimental results on 31 periodontitis radiograph images in terms of mean true positive fraction and false positive fraction are about 92.5% and 14.0%, respectively, where the ground truth is provided by a dentist. The results also demonstrate that ABLIfBm outperforms (a) the threshold segmentation method using either feature alone or a weighted average of the same two features but with weights trained differently; (b) a level set segmentation method presented earlier in literature; and (c) segmentation methods based on Bayesian, K-NN, or SVM classifier using the same two features. CONCLUSION: Our results suggest that the proposed method can effectively localize alveolar bone-loss areas in periodontitis radiograph images and hence would be useful for dentists in evaluating degree of bone-loss for periodontitis patients.

Design and evaluation of a primer pair that detects both Norwalk- and Sapporo-like caliciviruses by RT-PCR.

A primer pair (p289/290) based on the RNA polymerase sequence of 25 prototype and currently circulating strains of human caliciviruses (HuCVs) was designed for the detection of both Norwalk-like caliciviruses (NLVs) and Sapporo-like caliciviruses (SLVs) by reverse transcription-polymerase chain reaction (RT-PCR). This primer pair produces RT-PCR products of 319 bp for NLVs and 331 bp for SLVs. The usefulness of this primer pair was shown by its detection of prototype NLVs (Norwalk, Snow Mountain, Hawaii and Mexico viruses) and SLVs (Sapporo/82, Hou/86, Hou/90 and Lon/92) and currently circulating strains of NLVs and SLVs in children and adults. This primer pair also detected more viruses in either NLV or SLV genera than previously designed primers. This primer pair is useful for broad detection of HuCVs for clinical and epidemiologic studies as well as for environmental monitoring.

Teeth segmentation of dental periapical radiographs based on local singularity analysis.

Teeth segmentation for periapical raidographs is one of the most critical tasks for effective periapical lesion or periodontitis detection, as both types of anomalies usually occur around tooth boundaries and dental radiographs are often subject to noise, low contrast, and uneven illumination. In this paper, we propose an effective scheme to segment each tooth in periapical radiographs. The method consists of four stages: image enhancement using adaptive power law transformation, local singularity analysis using Hölder exponent, tooth recognition using Otsu's thresholding and connected component analysis, and tooth delineation using snake boundary tracking and morphological operations. Experimental results of 28 periapical radiographs containing 106 teeth in total and 75 useful for dental examination demonstrate that 105 teeth are successfully isolated and segmented, and the overall mean segmentation accuracy of all 75 useful teeth in terms of (TP, FP) is (0.8959, 0.0093) with standard deviation (0.0737, 0.0096), respectively.

Coexistence of exchange bias and magnetization pinning in the MnO(x)/GaMnAs system.

Coexistence of exchange bias (H(E)) and magnetization (M) shift was observed in as-grown and field-annealed MnO(x)/Ga(0.95)Mn(0.05)As bilayers. It was found that H(E) initially decreases with the annealing time t(a) and then increases when t(a) > 30 min, while the M shift remains almost unchanged with t(a). X-ray photoelectron spectroscopy (XPS) analysis reveals that MnO(x) is composed of MnO and Mn(3)O(4), and the volume amount ratio of Mn(3)O(4) to MnO increases with increasing t(a). A simple model based on a uniform MnO-Mn(3)O(4) interface with constant 'pinned' uncompensated interfacial spins is proposed to account for the observed exchange-biased phenomena in the bilayers.

Concentration and detection of caliciviruses in water samples by reverse transcription-PCR.

Human caliciviruses (HuCVs) cause waterborne outbreaks of gastroenteritis. Standard indicators of a safe water supply do not adequately predict contamination of water by viruses, including HuCVs. We developed a method to concentrate and detect HuCVs in water samples by using a cultivable primate calicivirus (Pan-1) as a model. Viable Pan-1 was seeded in different types of water and then filtered with a 1MDS filter, eluted with beef extract (BE), and reconcentrated by polyethylene glycol (PEG) precipitation. The viruses in the final samples were tested by plaque assay or by reverse transcription (RT)-PCR following extraction of the RNA with Trizol. Pan-1 was more sensitive to high-pH treatment than poliovirus was; a pH 9.0 BE solution was found to recover 35% more viable Pan-1 than a pH 9.5 BE solution recovered. Pan-1 was recovered from small volumes of deionized, finished, ground, and surface waters at efficiencies of 94, 73, 67, and 64%, respectively, when samples were assayed after elution without further concentration. When larger volumes of water (up to 40 liters) were tested after elution and concentration with PEG, 38, 19, and 14% of the seeded Pan-1 were recovered from finished, ground, and surface waters, respectively. The limit of detection of Pan-1 by RT-PCR was estimated to be 0.75 to 1.5 PFU in 40 liters of finished water. This method may be adapted for monitoring HuCVs in drinking water and other types of water for public health safety.

Baculovirus expression and antigenic characterization of the capsid proteins of three Norwalk-like viruses.

Human caliciviruses (HuCVs) are antigenically diverse. The antigenic relationships among different HuCVs have been difficult to study because HuCVs cannot be passaged in the laboratory. In this study, we describe cloning, sequencing and expression of the viral capsid proteins of three HuCVs that were identified in outbreaks of acute gastroenteritis in Virginia in 1997-1998. Yields of the capsid proteins similar to previously expressed recombinant Norwalk virus were obtained using the baculovirus expression system. Recombinant VA97207 capsid protein (rVA97207) and rVA98387, but not rVA98115, formed virus-like particles (VLPs). All three recombinant capsid antigens detected seroresponses in patients involved in outbreaks of acute gastroenteritis associated with genetically homologous or related HuCVs. The antigenic relationships of the three strains were further characterized using hyperimmune antisera against the three capsid antigens as well as four previously characterized recombinant capsid antigens of Norwalk (rNV), Mexico (rMxV), Hawaii (rHV), and Grimsby viruses (rGrV). VA98387 shared 98% aa identity with GrV; rVA98387 was detected by antisera to GrV. VA98115 shared 87% aa identity with Desert Storm virus and 65% aa identity with prototype Norwalk virus (NV); rVA98115 reacted weakly with NV antisera. VA97207 shared 80% aa identity with Amsterdam and 75% aa identity with Leeds strains and rVA97207 was not detected by any of the heterologous antibodies. In conclusion, VA97207 and VA98115 may belong to CV antigenic types not previously expressed, while VA98387 is a GrV-like virus. Low levels of cross-reactive antibodies were detected between types. Further studies to characterize these antigens and to develop enzyme immune assays (EIAs) for these strains are in progress.

Diagnosis of human caliciviruses by use of enzyme immunoassays.

The application of molecular technologies, such as the expression of viral proteins in baculovirus, has provided a powerful approach to the diagnosis of human calicivirus (HuCV) infections. The baculovirus-expressed HuCV capsid protein self-assembles into virus-like particles, providing excellent reagents for immunologic assays, such as enzyme immunoassays (EIAs). Following the expression of the capsid protein of Norwalk virus, the capsid proteins of 8 other HuCV strains have been expressed in baculovirus. The unlimited supply of baculovirus-produced reagents for HuCVs allows these EIAs to be applied in large-scale clinical and epidemiological studies. Both the antigen and antibody-detection EIAs are highly sensitive. The antigen-detection EIAs are highly specific, but the antibody-detection EIAs are more broadly reactive. This article reviews baculovirus expression techniques used to produce HuCV capsid antigens, development of EIAs using these antigens, and application of these EIAs in studies of HuCV infection and illness.

Genetic diversity among sapoviruses.

Norovirus and Sapovirus are two genera of the family Caliciviridae that contain viruses that can cause acute gastroenteritis in humans. Noroviruses (NOR) are genetically highly diverse but limited studies of the genetic diversity of sapoviruses (SAP) have been reported. In this study we characterized twenty-five SAP detected in our laboratory from outbreaks or sporadic cases of acute gastroenteritis in children from different geographical locations and in adults involved in a cruise ship outbreak investigation and a nursing home outbreak. Based on significant differences of partial RNA polymerase sequences (278-286 nt), the 25 strains were grouped into 12 genetic clusters, including 9 potential new clusters. Extended sequence analysis of the capsid gene of selected strains representing five potential new clusters supported this grouping. Four strains (Hou7-1181/90, Mex340/90, Cruise ship/00 and Argentina39) had <84% amino acid (aa) identity to each other and to the published sequences in the GenBank. Mex14917/00 was almost identical to Stockholm/97/SE whose RNA polymerase sequence was unknown. Phylogenetic and distance analyses of the capsid region of the four new strains showed that Hou7-1181/90 and Argentina39 represent two new genogroups and Mex340/90 and Cruise ship/00 belong to two new clusters within the London/92 genogroup. Thus, based on the capsid sequences we propose to classify the currently known SAP into nine genetic clusters within five genogroups, including one genogroup that is represented by an animal calicivirus, the porcine enteric calicivirus (PEC).