Artificial Intelligence Model Assisting Thyroid Nodule Diagnosis and Management: A Multicenter Diagnostic Study

CONTEXT

It is not clear how to integrate artificial intelligence (AI)-based models into diagnostic workflows.

OBJECTIVE

To develop and validate a deep-learning-based AI model (AI-Thyroid) for thyroid cancer diagnosis, and to explore how this improves diagnostic performance.

METHODS

The system was trained using 19 711 images of 6163 patients in a tertiary hospital (Ajou University Medical Center; AUMC). It was validated using 11 185 images of 4820 patients in 24 hospitals (test set 1) and 4490 images of 2367 patients in AUMC (test set 2). The clinical implications were determined by comparing the findings of six physicians with different levels of experience (group 1: 4 trainees, and group 2: 2 faculty radiologists) before and after AI-Thyroid assistance.

RESULTS

The area under the receiver operating characteristic (AUROC) curve of AI-Thyroid was 0.939. The AUROC, sensitivity, and specificity were 0.922, 87.0%, and 81.5% for test set 1 and 0.938, 89.9%, and 81.6% for test set 2. The AUROCs of AI-Thyroid did not differ significantly according to the prevalence of malignancies (>15.0% vs ≤15.0%, P = .226). In the simulated scenario, AI-Thyroid assistance changed the AUROC, sensitivity, and specificity from 0.854 to 0.945, from 84.2% to 92.7%, and from 72.9% to 86.6% (all P < .001) in group 1, and from 0.914 to 0.939 (P = .022), from 78.6% to 85.5% (P = .053) and from 91.9% to 92.5% (P = .683) in group 2. The interobserver agreement improved from moderate to substantial in both groups.

CONCLUSION

AI-Thyroid can improve diagnostic performance and interobserver agreement in thyroid cancer diagnosis, especially in less-experienced physicians.

The diagnostic performance and clinical value of deep learning-based nodule detection system concerning influence of location of pulmonary nodule

BACKGROUND

The deep learning-based nodule detection (DLD) system improves nodule detection performance of observers on chest radiographs (CXRs). However, its performance in different pulmonary nodule (PN) locations remains unknown.

METHODS

We divided the CXR intrathoracic region into non-danger zone (NDZ) and danger zone (DZ). The DZ included the lung apices, paramediastinal areas, and retrodiaphragmatic areas, where nodules could be missed. We used a dataset of 300 CXRs (100 normal and 200 abnormal images with 216 PNs [107 NDZ and 109 DZ nodules]). Eight observers (two thoracic radiologists [TRs], two non-thoracic radiologists [NTRs], and four radiology residents [RRs]) interpreted each radiograph with and without the DLD system. The metric of lesion localization fraction (LLF; the number of correctly localized lesions divided by the total number of true lesions) was used to evaluate the diagnostic performance according to the nodule location.

RESULTS

The DLD system demonstrated a lower LLF for the detection of DZ nodules (64.2) than that of NDZ nodules (83.2, p = 0.008). For DZ nodule detection, the LLF of the DLD system (64.2) was lower than that of TRs (81.7, p < 0.001), which was comparable to that of NTRs (56.4, p = 0.531) and RRs (56.7, p = 0.459). Nonetheless, the LLF of RRs significantly improved from 56.7 to 65.6 using the DLD system (p = 0.021) for DZ nodule detection.

CONCLUSION

The performance of the DLD system was lower in the detection of DZ nodules compared to that of NDZ nodules. Nonetheless, RR performance in detecting DZ nodules improved upon using the DLD system.

CRITICAL RELEVANCE STATEMENT

Despite the deep learning-based nodule detection system's limitations in detecting danger zone nodules, it proves beneficial for less-experienced observers by providing valuable assistance in identifying these nodules, thereby advancing nodule detection in clinical practice.

KEY POINTS

• The deep learning-based nodule detection (DLD) system can improve the diagnostic performance of observers in nodule detection. • The DLD system shows poor diagnostic performance in detecting danger zone nodules. • For less-experienced observers, the DLD system is helpful in detecting danger zone nodules.

Monthly Alternating Injections of Aflibercept and Bevacizumab for Neovascular Age-Related Macular Degeneration

We investigated the efficacy of monthly alternating injections of aflibercept and bevacizumab (MAAB) for maintenance treatment in patients with neovascular age-related macular degeneration (AMD) who showed improvement with the initial monthly injections but presented with rapid worsening after conversion to bimonthly injections. We included 72 patients with neovascular AMD who showed improvement with loading injections of aflibercept. For maintenance treatment, bevacizumab was administered every alternate month between the bimonthly aflibercept injections in 24 (33.3%) eyes showing worsening (MAAB group). The other eyes were treated with aflibercept (BiA group) bimonthly. Baseline low retinal thickness, thick choroid, and presence of intraretinal fluid were associated with worsening after extending the injection intervals. Visual improvement was lower in the MAAB group than in the BiA group, but the final visual outcomes were comparable. Additional bevacizumab stabilized the early fluctuation of retinal thickness, thus maintaining long-term visual stability without increasing the risk of geographic atrophy or disciform scar until the second year. Previously treated eyes or those with polypoidal choroidal vasculopathy responded less to the initial loading doses and showed worsening under the bimonthly regimen. MAAB was effective in preventing anatomical and functional deterioration when bimonthly aflibercept proved insufficient for the maintenance treatment of neovascular AMD.

Usefulness of Silent MRA for Evaluation of Aneurysm after Stent-Assisted Coil Embolization

OBJECTIVE

To determine the usefulness of Silent MR angiography (MRA) for evaluating intracranial aneurysms treated with stent-assisted coil embolization.

MATERIALS AND METHODS

Ninety-nine patients (101 aneurysms) treated with stent-assisted coil embolization (Neuroform atlas, 71 cases; Enterprise, 17; LVIS Jr, 9; and Solitaire AB, 4 cases) underwent time-of-flight (TOF) MRA and Silent MRA in the same session using a 3T MRI system within 24 hours of embolization. Two radiologists independently interpreted both MRA images retrospectively and rated the image quality using a 5-point Likert scale. The image quality and diagnostic accuracy of the two modalities in the detection of aneurysm occlusion were further compared based on the stent design and the site of aneurysm.

RESULTS

The average image quality scores of the Silent MRA and TOF MRA were 4.38 ± 0.83 and 2.78 ± 1.04, respectively (p < 0.001), with an almost perfect interobserver agreement. Silent MRA had a significantly higher image quality score than TOF MRA at the distal internal carotid artery (n = 57, 4.25 ± 0.91 vs. 3.05 ± 1.16, p < 0.001), middle cerebral artery (n = 21, 4.57 ± 0.75 vs. 2.19 ± 0.68, p < 0.001), anterior cerebral artery (n = 13, 4.54 ± 0.66 vs. 2.46 ± 0.66, p < 0.001), and posterior circulation artery (n = 10, 4.50 ± 0.71 vs. 2.90 ± 0.74, p = 0.013). Silent MRA had superior image quality score to TOF MRA in the stented arteries when using Neuroform atlas (4.66 ± 0.53 vs. 3.21 ± 0.84, p < 0.001), Enterprise (3.29 ± 1.59 vs. 1.59 ± 0.51, p = 0.003), LVIS Jr (4.33 ± 1.89 vs. 1.89 ± 0.78, p = 0.033), and Solitaire AB stents (4.00 ± 2.25 vs. 2.25 ± 0.96, p = 0.356). The interpretation of the status of aneurysm occlusion exhibited significantly higher sensitivity with Silent MRA than with TOF MRA when using the Neuroform Atlas stent (96.4% vs. 14.3%, respectively, p < 0.001) and LVIS Jr stent (100% vs. 20%, respectively, p = 0.046).

CONCLUSION

Silent MRA can be useful to evaluate aneurysms treated with stent-assisted coil embolization, regardless of the aneurysm location and type of stent used.

Technical feasibility and efficacy of a standard needle magnetization system for ultrasound needle guidance in thyroid nodule-targeting punctures: a phantom study

PURPOSE

The aim of this study was to assess the feasibility and efficacy of an ultrasound needle guidance system (NGS) based on standard needle magnetization in a phantom study of thyroid nodule (TN)-targeting punctures.

METHODS

Six trainees and a staff radiologist performed TN-targeting punctures with or without the NGS in phantom models (group 1, experience <50 cases; group 2, experience ≥50 cases and <100 cases; group 3, experience ≥100 cases of TN-targeting punctures). The feasibility, technical success rate, number of punctures, and procedure time were recorded.

RESULTS

The feasibility of NGS was 98.6% (138/140). In group 1, the technical success rate increased from 60.0%±8.2% to 80.0%±8.2% when the NGS was used (P=0.046), with a reduction in the number of punctures from 2.2 to 1.2 (P=0.005). In group 2, the rate changed from 95.0%±5.8% to 100.0%±0.0% with the NGS (P=0.157), with a minimal decrease in the number of punctures from 1.1 to 1.0 (P=0.157). The procedure time significantly decreased in both groups (P=0.041 and P=0.010, respectively) when the NGS was used. In group 3, there were no significant differences in the technical success rate and the number of punctures according to whether the NGS was used (P=0.317 and P=0.317, respectively).

CONCLUSION

NGS using standard needle magnetization is technically feasible and has potential to improve the efficacy of TN-targeting punctures for less-experienced operators, especially beginners, according to the findings of this phantom study.

Genetic Profile and Associated Characteristics of 150 Korean Patients with Retinitis Pigmentosa

PURPOSE

Retinitis pigmentosa (RP) shows great diversity between genotypes and phenotypes, and it is important to identify the causative genes. This study aimed to analyze the molecular profiles, associated ocular characteristics, and progression of RP in Korean patients.

METHODS

All the genetic variants in patients with RP, identified using targeted next-generation sequencing (NGS) with a panel of 88 RP-related genes between November 2018 and November 2019, were retrospectively reviewed. All the patients underwent comprehensive ophthalmological evaluations, and their clinical and family histories were recorded. The best-corrected visual acuity (BCVA) deterioration and photoreceptor disruption progression rates were determined based on the major causative mutational genes using nonlinear mixed models, and the differences among them were investigated using the interaction effect.

RESULTS

Among the 144 probands, 82 variants in 24 causative genes were identified in 77 families (53.5%). Most of the RP cases were associated with autosomal recessive variants (N = 64 (44.4%)), followed by autosomal dominant (N = 10 (6.9%)) and X-linked variants (N = 3 (2.1%)). The four most frequently affected genes were EYS (N = 15 (10.4%)), USH2A (N = 12 (8.3%)), PDE6B (N = 9 (6.3%)), and RP1 (N = 8 (5.6%)). Epiretinal membranes and cystoid macular edema were frequently noted in the patients with USH2A (75.0%) and PDE6B (50.0%) variants, respectively. During the follow-up period, the BCVA and photoreceptor disruption changes were significantly different among the patients carrying the four common causative genes (P=0.014 and 0.034, resp.). Patients with PDE6B variants showed faster BCVA changes (0.2 LogMAR/10 years), and those with USH2A variants showed the fastest ellipsoid zone disruptions (-170.4 µm/year).

CONCLUSION

In conclusion, our genetic analysis using targeted NGS provides information about the prevalence of RP-associated mutations in Korean patients. Delineating clinical characteristics according to genetic variations may help clinicians identify subtype features and predict the clinical course of RP.

Clinical Usefulness of the Revised International Workshop for Ocular Sarcoidosis Criteria in Korean Patients

Purpose: To compare differences between the original criteria for diagnosis of ocular sarcoidosis (OS) (first International Workshop for OS [IWOS] 2009) and the revised criteria (sixth IWOS 2017), and their clinical usefulness when assessing OS in Korean patients. Methods: We analyzed patients with suspected OS who visited our tertiary referral ophthalmological and pulmonary clinic from 2007 to 2018. We diagnosed patients using both sets of criteria. Blood test and biopsy data (collected by physicians) and slit-lamp, fundus, and fluorescein angiography data (collected by ophthalmologists) were reviewed. Results: Thirty-four patients were diagnosed using both criteria. Of 32 patients who underwent biopsies, 31 had OS (96.87%). Using either set of criteria, 31 patients were diagnosed with definite OS and two with presumed OS. One patient diagnosed with possible OS using the previous criteria was diagnosed with presumed OS using the revised criteria. The new criteria add the lysozyme level, the CD4/CD8 ratio, and positron emission tomography imaging data to the old criteria and add the descriptors “presumed OS” and “probable OS”. There is no need to use the revised criteria in Korea; the biopsy and imaging data are adequately diagnostic. Conclusions: IWOS revised the OS diagnostic criteria by adding new parameters. However, this was unnecessary for Korea, where the biopsy and imaging data are adequately diagnostic.

Changes in high-sensitivity C-reactive protein levels and metabolic indices according to grip strength in Korean postmenopausal women

OBJECTIVE

This study aimed to investigate the changes in high-sensitivity C-reactive protein (hs-CRP) level and metabolic indices such as blood pressure, serum lipid level and serum glucose level according to grip strength in postmenopausal women.

METHOD

Data from participants (postmenopausal women) in the Seventh Korea National Health and Nutrition Examination Survey 2018 were analyzed. Absolute handgrip strength was the sum of the maximal grip strength of both hands, and relative handgrip was calculated as absolute handgrip divided by the body mass index. We performed linear regression analysis after adjusting for confounders to assess the influence of grip strength on hs-CRP level and metabolic indices.

RESULTS

Linear regression analysis showed that after adjusting for confounders, with an increased absolute grip strength, systolic blood pressure and hs-CRP levels were decreased; however, the changes were not significant for the remaining indices. Relative grip strength was associated with hs-CRP levels and metabolic indices. With a high relative grip strength, hs-CRP, blood pressure, fasting blood glucose, hemoglobin A1c and triglyceride levels were decreased, while the high-density lipoprotein cholesterol level was increased.

CONCLUSION

Our study evaluated the overall health status using grip strength in postmenopausal women. The grip strength adjusted by body size was suitable in evaluating the overall health status, including inflammatory and metabolic indices. Additionally, increased grip strength was associated with a better health status in postmenopausal women.

Glaucoma as a prognostic factor of central retinal vein occlusion: visual and anatomical outcomes and occurrence of ischaemic central retinal vein occlusion

PURPOSE

To compare the functional and anatomical outcomes of central retinal vein occlusion (CRVO) according to the presence of glaucoma before the onset of CRVO, and to assess whether pre-existing glaucoma affects the prognosis of CRVO in terms of development and conversion to ischaemic CRVO.

METHODS

In this retrospective cohort study, patients with treatment-naïve CRVO were enrolled between December 2009 and February 2019. The patients were classified into two groups according to the presence of pre-existing primary open-angle glaucoma at CRVO diagnosis. We reviewed medical records regarding basic demographics, ocular characteristics and treatments. The effects of pre-existing glaucoma on the occurrence of ischaemic CRVO were also investigated using Cox proportional hazard models.

RESULTS

Of 166 eyes from 166 patients, 26 (15.7%) had pre-existing glaucoma. The pre-existing glaucoma group revealed significantly older (69.4 ± 13.3 versus 56.5 ± 15.9) and lower BCVA at baseline (1.06 ± 0.75 versus 0.64 ± 0.58, logMAR) and final visits (1.56 ± 1.35 versus 0.64 ± 0.48, logMAR) (all p < 0.05) than non-glaucomatous group. In terms of perfusion status of CRVO, the glaucoma group showed higher incidence of ischaemic CRVO (30.8% versus 5.3%, p = 0.052) at initial and last visits as well as more disorganization of retinal inner layers (DRIL) at 3 months (76.0% versus 49.6%, p = 0.015). Pre-existing glaucoma (hazard ratio (HR) = 2.141, p = 0.014), lower vision at baseline (HR = 2.071, p = 0.001) and DRIL at 3 months (HR = 2.905, p = 0.011) were significant risk factors for the occurrence of ischaemic CRVO.

CONCLUSION

In patients with CRVO, pre-existing glaucoma was associated with poorer visual and anatomical outcomes, and played as a significant risk factor for the development and conversion to ischaemic CRVO with lower vision and presence of DRIL at early phase of CRVO.

CENTRAL RETINAL VEIN OCCLUSION IN YOUNG PATIENTS: Clinical Characteristics and Prognostic Factors

PURPOSE

To investigate the clinical characteristics and prognostic factors of young patients with central retinal vein occlusion (CRVO).

METHODS

This retrospective cohort study involved treatment-naïve patients with CRVO. Medical records regarding basic demographics, predisposing factors, ocular characteristics, and treatments were reviewed and compared according to age at CRVO onset.

RESULTS

We enrolled 263 patients, of whom 69 were younger patients. Younger patients had higher prevalence of nontraditional risk factors including physical or psychological stress (P = 0.032), hematologic abnormalities (P = 0.003), and better visual acuity at baseline and last visit (all P < 0.001) and were unlikely to undergo intravitreal injections (47.8 vs. 68.6%, P < 0.001) during follow-up. Younger patients had higher prevalence of paracentral acute middle maculopathy (28.1 vs. 4.7%, P < 0.001). Older age (odds ratio = 1.165, P = 0.028), male sex (odds ratio = 7.074, P = 0.034), coexisting renal disease (odds ratio = 7.845, P = 0.050), and poor baseline visual acuity (odds ratio = 16.069, P = 0.002) were significant risk factors for poor visual outcomes in young CRVO patients.

CONCLUSION

Younger CRVO patients had a milder clinical course with fewer treatments and were more likely to have nontraditional risk factors than older patients.

Comparison of Postoperative Nutritional Status after Distal Gastrectomy for Gastric Cancer Using Three Reconstructive Methods: a Multicenter Study of over 1300 Patients

PURPOSE

Perioperative nutritional status has been reported to be associated with short- and long-term outcomes after surgery in gastric cancer patients. This study compared changes in nutritional status after distal gastrectomy using the Billroth I (BI), Billroth II (BII), and Roux-en-Y (RY) reconstruction techniques in gastric cancer patients.

MATERIALS AND METHODS

Data from 1305 gastric cancer patients who underwent distal gastrectomy at two tertiary hospitals from January 2011 to December 2016 were reviewed. The patients were divided into three groups according to reconstruction type: BI, BII, and RY. We evaluated changes in nutritional parameters including body mass index (BMI), biochemical data, the prognostic nutritional index (PNI), nutritional risk index (NRI), and geriatric nutritional risk index (GNRI) preoperatively, and 3, 6, and 12 months after surgery.

RESULTS

Total protein, albumin, PNI, and NRI were significantly lower in the BII group than in the BI and RY groups during follow-up (P < 0.001). In multivariate analysis, reconstruction types were independently related to decreases in BMI (> 10%), low serum protein, albumin, and cholesterol 12 months after surgery. Compared with BI, BII was associated with decreased BMI, low protein, and albumin and RY was associated with decreased BMI and low cholesterol.

CONCLUSION

During the first year after gastric cancer surgery, postoperative nutritional status differed according to the reconstruction type; BI resulted in the least weight and nutritional loss, RY yielded results comparable with BI in the nutritional indexes, and BII resulted in the greatest nutritional loss.

A comparison of short-term postoperative outcomes including nutritional status between gastrectomy with simultaneous cholecystectomy and gastrectomy only in patients with gastric cancer

Objective

We aimed to evaluate the effect of simultaneous cholecystectomy on the short-term postoperative outcomes and nutritional status in patients with gastric cancer.

Methods

We retrospectively reviewed data from 4,820 patients with gastric cancer who underwent gastrectomy from January 2011 to December 2016. Patients who underwent only gastrectomy (N=4,578) were matched to those who underwent simultaneous cholecystectomy during gastrectomy (N=242) at a 1:1 ratio using propensity score matching analysis. The nutritional status and inflammatory responses preoperatively and postoperatively and postoperative outcomes were compared between the groups.

Results

The simultaneous cholecystectomy group showed more intraoperative blood loss and a longer operative time than the gastrectomy only group [150.0 (100.0, 200.0) mL vs. 100.0 (100.0, 200.0) mL, P=0.006; 176.0 (150.0, 210.0) min vs. 155.0 (128.0, 188.0) min, P<0.001, respectively]. Intraoperative event rate, postoperative complication rate, and postoperative recovery did not differ between the groups. All parameters including body weight, the hemoglobin level, absolute lymphocyte count, total protein level, albumin level, fasting glucose level, and prognostic nutritional index excluding the cholesterol level were not significantly different between the groups, and their changing patterns were similar. Although the cholesterol level was significantly lower in the simultaneous cholecystectomy group than in the gastrectomy only group at all follow-up points, the mean value of the decreased cholesterol level was within normal range.

Conclusions

In gastric cancer patients with gallbladder disease, simultaneous cholecystectomy is safe and not associated with additional nutritional loss.

Short-Term Outcomes of Intracorporeal Delta-Shaped Gastroduodenostomy Versus Extracorporeal Gastroduodenostomy after Laparoscopic Distal Gastrectomy for Gastric Cancer

Background

Billroth I anastomosis is one of the most common reconstruction methods after distal gastrectomy for gastric cancer. Intracorporeal Billroth I (ICBI) anastomosis and extracorporeal Billroth I (ECBI) anastomosis are widely used in laparoscopic surgery. Here we compared ICBI and ECBI outcomes at a major gastric cancer center.

Methods

We retrospectively analyzed data from 2,284 gastric cancer patients who underwent laparoscopic distal gastrectomy between 2009 and 2017. We divided the subjects into ECBI (n=1,681) and ICBI (n=603) groups, compared the patients' clinical characteristics and surgical and short-term outcomes, and performed risk factor analyses of postoperative complication development.

Results

The ICBI group experienced shorter operation times, less blood loss, and shorter hospital stays than the ECBI group. There were no clinically significant intergroup differences in diet initiation. Changes in white blood cell counts and C-reactive protein levels were similar between groups. Grade II-IV surgical complication rates were 2.7% and 4.0% in the ECBI and ICBI groups, respectively, with no significant intergroup differences. Male sex and a body mass index (BMI) ≥30 were independent risk factors for surgical complication development. In the ECBI group, patients with a BMI ≥30 experienced a significantly higher surgical complication rate than those with a lower BMI, while no such difference was observed in the ICBI group.

Conclusion

The surgical safety of ICBI was similar to that of ECBI. Although the chosen anastomotic technique was not a risk factor for surgical complications, ECBI was more vulnerable to surgical complications than ICBI in patients with a high BMI (≥30).

Relationship between Progressive Changes in Lamina Cribrosa Depth and Deterioration of Visual Field Loss in Glaucomatous Eyes

Purpose

To investigate the relationship between the progression of visual field (VF) loss and changes in lamina cribrosa depth (LCD) as determined by spectral-domain optical coherence tomography (SD-OCT) enhanced depth imaging in patients with primary open angle glaucoma (POAG).

Methods

Data from 60 POAG patients (mean follow-up, 3.5 ± 0.7 years) were included in this retrospective study. The LCD was measured in the optic disc image using SD-OCT enhanced depth imaging scanning at each visit. Change in the LCD was considered to either ‘increase’ or ‘decrease’ when the differences between baseline and the latest two consecutive follow-up visits were greater than the corresponding reproducibility coefficient value (23.08 µm, as determined in a preliminary reproducibility study). All participants were divided into three groups: increased LCD (ILCD), decreased LCD (DLCD), and no LCD change (NLCD). The Early Manifest Glaucoma Trial criteria were used to define VF deterioration. Kaplan-Meier survival analysis and Cox's proportional hazard models were performed to explore the relationship between VF progression and LCD change.

Results

Of the 60 eyes examined, 35.0% (21 eyes), 28.3% (17 eyes), and 36.7% (22 eyes) were classified as the ILCD, DLCD, and NLCD groups, respectively. Kaplan-Meier survival analysis showed a greater cumulative probability of VF progression in the ILCD group than in the NLCD (p < 0.001) or DLCD groups (p = 0.018). Increased LCD was identified as the only risk factor for VF progression in the Cox proportional hazard models (hazard ratio, 1.008; 95% confidence interval, 1.000 to 1.015; p = 0.047).

Conclusions

Increased LCD was associated with a greater possibility of VF progression. The quantitative measurement of LCD changes, determined by SD-OCT, is a potential biomarker for the prediction of VF deterioration in patients with POAG.

Surgeon volume and prognosis of patients with advanced papillary thyroid cancer and lateral nodal metastasis

Background

Surgery is the most important treatment modality for papillary thyroid cancer (PTC). However, the relationship between surgeon volume and long-term oncological outcomes has not been explored.

Methods

Patients diagnosed with N1b PTC after initial thyroid surgery between 1 July 1994 and 31 December 2011 were eligible for inclusion in the study. Surgeons were categorized into high (at least 100 operations per year) and low (fewer than 100 operations per year) volume groups. Kaplan–Meier survival analysis according to surgeon volume was performed, and Cox proportional hazard modelling was used to estimate hazard ratios (HRs) with 95 per cent confidence intervals according to patient, tumour and surgeon factors.

Results

A total of 1103 patients with a median follow-up of 81 (i.q.r. 62–108) months were included in the study. During follow-up, 200 patients (18·1 per cent) developed structural recurrence. A high surgeon volume was associated with low structural recurrence (P = 0·006). After adjustment for age, sex and conventional risk factors for recurrence (histology, tumour size, gross extrathyroidal extension, margin status, more than 5 positive lymph nodes, radioactive iodine therapy), the adjusted HR for structural recurrence for low-volume surgeons was 1·46 (95 per cent c.i. 1·08 to 1·96), compared with high-volume surgeons. Distant metastasis (P = 0·242) and disease-specific mortality (P = 0·288) were not affected by surgeon volume.

Conclusion

Surgeon volume is associated with structural recurrence, but not distant metastasis or cancer-specific death in patients with N1b PTC. Surgeon volume is important in initial surgery for advanced PTC with extensive nodal metastasis in order to ensure curative outcome and reduce treatment-related morbidity.

A simple method for tension-free Billroth I anastomosis after gastrectomy for gastric cancer

Billroth I anastomosis (B-I) is a popular reconstructive procedure performed after distal gastrectomy for the treatment of gastric cancer. Herein we introduce a new and simple technique to minimize tension after Billroth I for gastric cancer.

Stimulating TRPV1 externalization and synthesis in dorsal root ganglion neurons contributes to PGE2 potentiation of TRPV1 activity and nociceptor sensitization

BACKGROUND

Persistent peripheral sensitization contributes to chronic pain. Plasticity of nociceptive dorsal root ganglion (DRG) neurons (nociceptors) induced by pro-inflammatory mediators contributes to sensitization. Prostaglandin E2 (PGE2) enriched in injured tissues is known not only directly to sensitize DRG neurons, but also to potentiate sensitizing effects of other pain mediators such as capsaicin and its receptor transient receptor potential vanilloid-1 (TRPV1). It remains unknown whether PGE2 potentiates TRPV1 activity by stimulating its synthesis, cell surface and axonal trafficking in DRG neurons.

METHODS

Combined biochemical, morphological, pharmacological and behavioral approaches have been used to address this issue in both in vitro and in vivo models.

RESULTS

PGE2 increased TRPV1 externalization in cultured rat DRG neurons in a time- and concentration-dependent manner, an event blocked by an inhibitor of protein synthesis or anterograde export. EP1 and EP4, but not EP2 and EP3, mediated this event. EP1 agonist-induced TRPV1 externalization was suppressed by inhibitors of CaMKII, PLC, PKC and PKCε, while EP4 agonist-induced TRPV1 externalization by inhibitors of cAMP/PKA and ERK/MAPK. Pre-exposure to PGE2 potentiated release of calcitonin gene-related peptide from cultured DRG neurons evoked by subsequent capsaicin stimulation. This event was blocked by an inhibitor of protein synthesis or export, suggesting that PGE2-induced TRPV1 synthesis and externalization is coupled to enhanced TRPV1 activity. Pre-exposure to PGE2 not only prolonged tactile allodynia evoked by subsequent capsaicin challenge, but also increased TRPV1 levels in L4-6 DRG, sciatic nerves and plantar skin.

CONCLUSIONS

Our data indicate that facilitating TRPV1 synthesis, cell surface and axonal trafficking is a novel mechanism underlying PGE2 potentiation of TRPV1 activity.

Oncologic Safety of Laparoscopic Wedge Resection with Gastrotomy for Gastric Gastrointestinal Stromal Tumor: Comparison with Conventional Laparoscopic Wedge Resection

Purpose

Various laparoscopic wedge resection (LWR) techniques requiring gastrotomy for gastrointestinal stromal tumors (GISTs) of the stomach have been applied to facilitate tumor resection and preserve the remnant gastric volume. However, there is the possibility of cancer cell dissemination during these procedures. The aim of this study was to assess the oncologic safety of LWR with gastrotomy (LWR-G) compared to LWR without luminal exposure.

Materials and Methods

Clinicopathologic and operative results of 193 patients who underwent LWR for gastric GIST were retrospectively analyzed from 2003 to 2013. We stratified the patients into two groups: LWR-G and LWR without gastrotomy (LWR-C). Clinicopathologic features, short-term outcomes, and long-term outcomes were compared.

Results

A total of 26 patients underwent LWR-G, and 167 patients underwent LWR-C. The LWR-G group showed significantly more anterior wall-located (n=10, 38.5%), intraluminal (n=20, 76.9%), and ulcerative (n=13, 50.0%) tumors than the LWR-C group (n=33, 19.8%; n=96, 57.5%; n=46, 27.5%, respectively). Postoperative short-term outcomes did not differ between the two groups. When tumor staging was compared, no statistical difference was noted. There was no recurrence in the LWR-G group, while 2 patients in the LWR-C group experienced recurrence. The two recurrences in the LWR-C group were found in the liver and in the remnant stomach at 63 and 12 months after the operation, respectively. No gastric GIST-related death was recorded in any group during the study period.

Conclusions

LWR-G for gastric GIST is an oncologically safe procedure even for masses with ulcerations.

P4-11-20: Observational Study of Body Weight Changes and Metabolic Syndrome in Breast Cancer Patients Receiving Adjuvant Therapy: Characteristics of Dietary Pattern in Korean Breast Cancer Patients

Backgroud: Obesity, postdiagnosis weight gain, and presence of metabolic syndrome in breast cancer are reported to adversely affect survival among breast cancer survivors. Most of the studies on weight gain and metabolic syndrome in breast cancer are from Western countries and few information is available on Asian population. We designed this prospective observational study to characterize weight and metabolic changes during adjuvant treatment in women with early breast cancer and to identify factors associated with occurrence of metabolic syndrome, focusing on dietary pattern.

Methods: Patients aged 18–75 who underwent curative surgery with stage I-III invasive breast cancer were enrolled from 2008 to 2010. We measured glucose (FBS), hemoglobin A1c (HbA1c), total cholesterol (TC), HDL cholesterol, and triglyceride (TG) level in fasting serum samples before starting adjuvant therapy, at 6 months and 12 months after enrollment. Body weight, body mass index (BMI), body fat mass, and percent body fat at baseline, 6 months, and 12 months were also measured. Dietary intake was assessed using valid semi-quantitative Food frequency questionnaire (FFQ).

Results: Total of 63 patients were enrolled. Median age of the enrolled patients were 48 (range, 25–68), with premenopausal/postmenopausal 40 (63.5%)/ 23 (36.5%). Fifty (82.0%) and 10 (16.4%) received adjuvant chemotherapy followed by hormone therapy and hormone therapy alone. Hormone receptor positive (ER+/PR+) and HER2 positive cancer accounted for 52 (83.9%) and 7 (12.1%). Mean FBS, HbA1c, TC, HDL, and TG level was 99.9 mg/dL (range, 83–159), 5.59 mg/dL (range, 4.8−7.5), 197.4 mg/dL (125-298), 51.9 mg/dL (range, 30–90), and 119.7 mg/dL (42-371). Mean height, weight, and BMI was 158 cm (range, 149–169), 61.7kg (range, 46.2−96.0), and 24.7 kg/m2 (range, 18.7−35.7), respectively. According to the WHO and NTH guidelines for Asian, normal (BMI 18.5−22.9), overweight (BMI 23–24.9), and obesity (BMI≥25) was 18 (28.6%), 13 (20.6%), and 32 (50.8%), respectively. Number of patients with metabolic syndrome was 18 (34%). Mean BMI (26.1 vs 24.0, p=0.021) and TG (180.6 vs 92.0, p&lt;0.001) was higher, HDL cholesterol was lower (42.2 vs 57.3, p&lt;0.001) in patients with metabolic syndrome. Composition of daily calorie intake consisted of 13.5% (range 10.7−21.8) of protein, 6.7% (range, 3.3−22.1) of fat, and 70.1% (range, 28.1−79.5) of carbohydrate. The presence of metabolic syndrome was associated with a higher carbohydrate intake (carbohydrate intake per ideal body weight&gt;6.0) (p=0.071). The TG level of patients who indigested high carbohydrate was significantly higher (143.8 vs 102.9, p=0.023). The HDL level of patients who took high fat diet (&gt;20% of total calorie) was lower (45.3 vs 53.5, p=0.045).

Conclusion: In our cohort of Korean breast cancer patients, 34% had metabolic syndrome at baseline. Those patients with metabolic syndrome consumed higher proportion of carbohydrate, which resulted in significantly higher level of TG. Our data suggest that composition of calorie intake is different in Asian population compared to Western countries, warranting for reappraisal on the recommendation on life style modification and diet.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-11-20.

Which oblique plane is more helpful in diagnosing an anterior cruciate ligament tear?

AIM

To evaluate the diagnostic role of additional oblique coronal and oblique sagittal magnetic resonance imaging (MRI) for an anterior cruciate ligament (ACL) tear.

MATERIALS AND METHODS

A total of 101 patients who had undergone preoperative knee MRI examinations with orthogonal and two sets of oblique images were enrolled in the study. Two radiologists evaluated the MRI images by the use of four methods: orthogonal images only (method A); orthogonal and additional oblique coronal images (method B); orthogonal and oblique sagittal images (method C); and orthogonal images with oblique coronal and sagittal images (method D). The status of the ACL (normal or tear) was determined by consensus. The sensitivity, specificity, and accuracy for an ACL tear with the use of each method were calculated in comparison with arthroscopy as the reference standard, and values were statistically analysed using the McNemar test. The diagnostic accuracies were compared using receiver operating characteristic (ROC) analysis.

RESULTS

Arthroscopy identified 10 partial ACL tears and 30 complete ACL tears. The specificities and accuracies for methods B, C, and D were significantly higher than the specificities and accuracies for method A (p<0.05). There was no significant difference in the sensitivity, specificity, and accuracy for methods B, C, and D. Diagnostic ability was not significantly different for each method, as determined by ROC analysis (p>0.05).

CONCLUSIONS

Additional oblique imaging for an ACL tear improved the specificity. Either of the oblique imaging methods is sufficient, and no further improvement in the diagnostic efficacy was achieved by simultaneous use.

Promoter methylation of p16, DAPK, CDH1, and TIMP-3 genes in cervical cancer: correlation with clinicopathologic characteristics

This study was conducted to investigate the promoter methylation status of the p16, DAPK, CDH1, and TIMP-3 genes in primary cervical cancer and its correlation with clinicopathologic characteristics. Promoter methylation was evaluated using a methylation-specific polymerase chain reaction in 78 cervical cancer tissue specimens and 24 control, normal cervical tissue specimens. Clinicopathologic parameters were obtained from medical records, and the relationship between the discrete variables and the methylation status was evaluated. The frequencies of promoter methylation of p16, DAPK, CDH1, and TIMP-3 in cervical cancer were 57%, 44.9%, 52.6%, and 9%, respectively. Primary cervical cancer had significantly higher methylation frequencies for the p16 and DAPK promoters than did the control, normal cervix (P < 0.0001). The promoter methylation of TIMP-3 was significantly higher in adenocarcinoma than in squamous cell carcinoma (41.7% vs 3%, respectively, P= 0.0175). High-stage cancers exhibited an increased promoter methylation frequency for p16 (P= 0.0061). The promoter methylation of the p16 gene is a frequent event in cervical carcinogenesis and may have potential clinical application as a marker for the progression and prognosis of cancer.

A two-year longitudinal study of dental caries in permanent first molars of Korean elementary schoolchildren

OBJECTIVE

This longitudinal study investigated dental caries increment in permanent first molars of Korean elementary schoolchildren.

METHODS

A convenience sample of 722 children aged 7-9 years attending one urban elementary school was examined at baseline, with follow-up examinations at one and two years. Coronal surfaces of permanent first molars were scored with regard to caries experience and sealant status.

RESULTS

Among sound occlusal surfaces at baseline, 21 percent of upper and 25 percent of lower surfaces developed caries during the two-year interval. In teeth that erupted between baseline and the first follow-up exam, over 10 percent of occlusal surfaces developed caries. Pit and fissure caries accounted for 93 percent of all new carious surfaces, while sealants had been placed on 16 percent of occlusal surfaces during the study.

CONCLUSIONS

Recognizing the limitations of this convenience sample, dental sealants should be used more widely in this Korean population, and should be applied soon after tooth eruption.

Postprandial hypertriglyceridemia impairs endothelial function by enhanced oxidant stress

AIMS

it appears that hypertriglyceridemia (HTG) is a risk factor of atherosclerosis as demonstrated by recent studies. In this study, we analyzed the effects of acute HTG on endothelial function and oxidative stress, which are important mechanisms in the pathogenesis of atherosclerosis.

METHODS AND RESULTS

in a high fat meal group (n = 11), serum triglycerides and PMA-activated leukocyte O(2)(-)* production were significantly (P < 0.005) increased from 146 +/- 69 mg/dl and 4.09 +/- 0.93 nmol/10(6) cells/min preprandially to 198 +/- 88 mg/dl and 5.49 +/- 1.19 nmol/10(6) cells/min, respectively, 2 h after eating a high-fat meal. The flow-mediated endothelium-dependent brachial artery dilation (FMD; high-resolution ultrasound) was decreased from 13.7 +/- 3.3% preprandially to 8.2 +/- 3.7%, 2 h after eating a high-fat meal (P < 0.005). However, following a low-fat meal (n = 9), there were no significant changes in triglycerides, leukocyte O(2)(-)* production and FMD. Changes of serum triglycerides were correlated negatively (r = -0.650, P < 0.005) with changes of FMD, but were correlated positively (r = 0.798, P < 0.001) with changes of leukocyte O(2)(-)* production, which - in turn - were correlated negatively (r = -0.784, P < 0.001) with changes of FMD in all study subjects (mean age: 56 years, n = 20).

CONCLUSIONS

this study suggests that acute HTG causes endothelial dysfunction via enhanced oxidant stress and this may pave the way for the development of atherosclerosis under chronic conditions.

Estrogen modulation of prolactin gene expression requires an intact mitogen-activated protein kinase signal transduction pathway in cultured rat pituitary cells

Expression of the PRL gene is regulated by many factors, including cAMP, estradiol (E2), phorbol esters, epidermal growth factor (EGF), and TRH. The promoter region of the rat PRL gene has been shown to contain DNA sequences that are thought to support the direct interaction of estrogen receptors (ERs) with DNA. It is by this direct ER/DNA interaction that estrogen is thought to modulate expression of PRL. We report here that estrogeninduced PRL expression requires an intact mitogen-activated protein kinase (MAPK) signal transduction pathway in cultured rat pituitary cells (PR1 lactotroph and GH3 somatolactotroph cell lines). Interfering with the MAPK signaling cascade by inhibiting the activity of MAPK kinase (MEK) ablates the ability of estrogen to induce PRL mRNA and protein. In these cell lines, estrogen activates extracellular regulated protein kinases ERK-1 and ERK-2 enzyme activities maximally within 10 min of 1 nM E2 treatment. This activity is blocked by pretreatment of the cells with the MEK inhibitors PD98059 and UO126. The mechanism by which ERKs-1 and -2 are activated by estrogen appears to be independent of c-Src since the effects of estrogen on PRL gene expression are not affected by herbimycin A or PP1 administration. c-Raf-1 may be involved in the effects of E2 because estrogen causes the rapid and transient tyrosine phosphorylation of c-Raf-1. The ER antagonist ICI 182,780 blocks both ERK-1 and ERK-2 activation in addition to PRL protein and mRNA, implying a central role for the classical ER in the activation of the MAPK pathway resulting in PRL gene expression.

Pituitary apoplexy in a patient with acute myeloid leukemia and thrombocytopenia

We describe a 72-year-old woman with a history of acute myeloid leukemia who developed pituitary apoplexy associated with thrombocytopenia secondary to chemotherapy. She presented with new onset severe headache, nausea, vomiting and blurred vision. Initial physical examination was unremarkable. CT scan of the head was initially negative. Upon admission for further work up, She developed a high-grade fever, hypotension and obtundation. Subsequent physical examination revealed bitemporal visual fields defects and decreased visual acuity. Repeat imaging of head revealed a hemorrhagic pituitary mass compressing the optic chiasm. Laboratory results were compatible with the diagnosis of pan-hypopituitary syndrome. She received high dose steroids and was transferred for transnasal sphenoidotomy decompression surgery. The visual defects improved postoperatively. A literature review of Pituitary apoplexy is presented. Pituitary apoplexy secondary to thrombocytopenia has never been reported.

Epidermal growth factor-stimulated tyrosine phosphorylation of caveolin-1. Enhanced caveolin-1 tyrosine phosphorylation following aberrant epidermal growth factor receptor status

Caveolin-1 is the major coat protein of caveolae and has been reported to interact with various intracellular signaling molecules including the epidermal growth factor (EGF) receptor. To investigate the involvement of caveolin-1 in EGF receptor action, we used mouse B82L fibroblasts transfected with (a) wild type EGF receptor, (b) a C-terminally truncated EGF receptor at residue 1022, (c) a C-terminally truncated EGF receptor at residue 973, or (d) a kinase-inactive EGF receptor (K721M). Following EGF treatment, there was a distinct electrophoretic mobility shift of the caveolin-1 present in cells expressing the truncated forms of the EGF receptor, but this shift was not detectable in cells bearing either normal levels of the wild type EGF receptor or a kinase-inactive receptor. This mobility shift was also not observed following the addition of other cell stimuli, such as platelet-derived growth factor, insulin, basic fibroblast growth factor, or phorbol 12-myristate 13-acetate. Analysis of caveolin-1 immunoprecipitates from EGF-stimulated or nonstimulated cells demonstrated that the EGF-induced mobility shift of caveolin-1 was associated with its tyrosine phosphorylation in cells expressing truncated EGF receptors. Maximal caveolin-1 phosphorylation was achieved within 5 min after exposure to 10 nM EGF and remained elevated for at least 2 h. Additionally, several distinct phosphotyrosine-containing proteins (60, 45, 29, 24, and 20 kDa) were co-immunoprecipitated with caveolin-1 in an EGF-dependent manner. Furthermore, the Src family kinase inhibitor, PP1, does not affect autophosphorylation of the receptor, but it does inhibit the EGF-induced mobility shift and phosphorylation of caveolin-1. Conversely, the MEK inhibitors PD98059 and UO126 could attenuate EGF-induced mitogen-activated protein kinase activation, they do not affect the EGF-induced mobility shift of caveolin-1. Because truncation and overexpression of the EGF receptor have been linked to cell transformation, these results provide the first evidence that the tyrosine phosphorylation of caveolin-1 occurs via an EGF-sensitive signaling pathway that can be potentiated by an aberrant activity or expression of various forms of the EGF receptor.

Platelet-derived growth factor-stimulated migration of murine fibroblasts is associated with epidermal growth factor receptor expression and tyrosine phosphorylation

Previous studies have shown that epidermal growth factor (EGF) synergizes with various extracellular matrix components in promoting the migration of B82L fibroblasts expressing wild-type EGF receptors and that functional EGF receptors are critical for the conversion of B82L fibroblasts to a migratory cell type (). In the present study, we examined the effects of platelet-derived growth factor (PDGF) on the motility of B82L fibroblasts using a microchemotaxis chamber. We found that PDGF can enhance fibronectin-induced migration of B82L fibroblasts expressing wild-type EGF receptors (B82L-clone B3). However, B82L cells that lack the EGF receptor (B82L-parental) or that express an EGF receptor that is kinase-inactive (B82L-K721M) or C-terminally truncated (B82L-c'973) exhibit little PDGF-stimulated migration. In addition, none of these three cell lines exhibit the capacity to migrate to fibronectin alone. These observations indicate that, similar to cell migration toward fibronectin, PDGF-induced cell migration of B82L fibroblasts is augmented by the expression of an intact EGF receptor kinase. The loss of PDGF-stimulated motility in B82L cells that do not express an intact EGF receptor does not appear to result from a gross dysfunction of PDGF receptors, because ligand-stimulated tyrosine phosphorylation of the PDGF-beta receptor and the activation of mitogen-activated protein kinases are readily detectable in these cells. Moreover, an interaction between EGF and PDGF receptor systems is supported by the observation that the EGF receptor exhibits an increase in phosphotyrosine content in a time-dependent fashion upon the addition of PDGF. Altogether, these studies demonstrate that the expression of EGF receptor is critical for PDGF-stimulated migration of murine B82L fibroblasts and suggest a role for the EGF receptor downstream of PDGF receptor activation in the signaling events that lead to PDGF-stimulated cell motility.

A case of aortocoronary dissection as a complication during a percutaneous transluminal coronary angioplasty (PTCA)

We report a case of aortocoronary dissection during a percutaneous transluminal coronary angioplasty (PTCA) which resulted from an antegrade and also a progressively retrograde extension of the coronary dissection into the Sinus of Valsalva and the ascending aorta. It was successfully treated with stenting without an operation, resulting in optimal coronary blood flow and diminution of the aortic dissection.

Effect of prenatal ethanol exposure on the developmental profile of the NMDA receptor subunits in rat forebrain and hippocampus

The effects of prenatal ethanol exposure on the NMDAR1 protein expression (postnatal days 1 and 7) and on the developmental profile of the NMDAR2A and NMDAR2B subunits in rat forebrain and hippocampus were investigated. Forebrain and hippocampal membrane proteins were isolated from pups of various ages (postnatal days 1 to 21) from prenatally ethanol exposed, pair-fed and ad libitum control groups. A semiquantitative immunoblot procedure was used with antibodies raised against the NMDAR1, NMDAR2A, and the NMDAR2B subunits to assess the NMDA subunit protein expression in the samples. NMDAR1 protein expression was unaffected by prenatal ethanol exposure at postnatal day 1 or 7 in both the forebrain and hippocampus. NMDAR2A protein expression levels rose rapidly in both forebrain and hippocampus during the time frame of study. Prenatal ethanol exposure caused a significant reduction in protein expression levels of the NMDAR2A in forebrain through postnatal day 14. NMDAR2B protein expression levels were high throughout the study in both forebrain and hippocampus. Prenatal ethanol exposure significantly reduced protein expression of the NMDAR2B in the forebrain (through postnatal day 14) and hippocampus (up to day 7). The results suggest that there may be a link between the depressed expression of the NMDAR2 subunits and the neurodevelopmental disorders associated with fetal ethanol exposure.

Coronavirus transcription mediated by sequences flanking the transcription consensus sequence

In our studies of murine coronavirus transcription, we continue to use defective interfering (DI) RNAs of mouse hepatitis virus (MHV) in which we insert a transcription consensus sequence in order to mimic subgenomic RNA synthesis from the nondefective genome. Using our subgenomic DI system, we have studied the effects of sequences flanking the MHV transcription consensus sequence on subgenomic RNA transcription. We obtained the following results. (i) Insertion of a 12-nucleotide-long sequence including the UCUAAAC transcription consensus sequence at different locations of the DI RNA resulted in different efficiencies of subgenomic DI RNA synthesis. (ii) Differences in the amount of subgenomic DI RNA were defined by the sequences that flanked the 12-nucleotide-long sequence and were not affected by the location of the 12-nucleotide-long sequence on the DI RNA. (iii) Naturally occurring flanking sequences of intergenic sequences at gene 6-7, but not at genes 1-2 and 2-3, contained a transcription suppressive element(s). (iv) Each of three naturally occurring flanking sequences of an MHV genomic cryptic transcription consensus sequence from MHV gene 1 also contained a transcription suppressive element(s). These data showed that sequences flanking the transcription consensus sequence affected MHV transcription.

Characterization of a murine coronavirus defective interfering RNA internal cis-acting replication signal

The mouse hepatitis virus (MHV) sequences required for replication of the JHM strain of MHV defective interfering (DI) RNA consist of three discontinuous genomic regions: about 0.47 kb from both terminal sequences and a 0.13-kb internal region present at about 0.9 kb from the 5' end of the DI genome. In this study, we investigated the role of the internal 0.13-kb region in MHV RNA replication. Overall sequences of the 0.13-kb regions from various MHV strains were similar to each other, with nucleotide substitutions in some strains; MHV-A59 was exceptional, with three nucleotide deletions. Computer-based secondary-structure analysis of the 0.13-kb region in the positive strand revealed that most of the MHV strains formed the same or a similar main stem-loop structure, whereas only MHV-A59 formed a smaller main stem-loop structure. The RNA secondary structures in the negative strands were much less uniform among the MHV strains. A series of DI RNAs that contained MHV-JHM-derived 5'- and 3'-terminal sequences plus internal 0.13-kb regions derived from various MHV strains were constructed. Most of these DI RNAs replicated in MHV-infected cells, except that MRP-A59, with a 0.13-kb region derived from MHV-A59, failed to replicate. Interestingly, replication of MRP-A59 was temperature dependent; it occurred at 39.5 degrees C but not at 37 or 35 degrees C, whereas a DI RNA with an MHV-JHM-derived 0.13-kb region replicated at all three temperatures. At 37 degrees C, synthesis of MRP-A59 negative-strand RNA was detected in MHV-infected and MRP-A59 RNA-transfected cells. Another DI RNA with the internal 0.13-kb region deleted also synthesized negative-strand RNA in MHV-infected cells. MRP-A59-transfected cells were shifted from 39.5 to 37 degrees C at 5.5 h postinfection, a time when most MHV negative-strand RNAs have already accumulated; after the shift, MRP-A59 positive-strand RNA synthesis ceased. The minimum sequence required for maintenance of the positive-strand major stem-loop structure and biological function of the MHV-JHM 0.13-kb region was about 57 nucleotides. Function was lost in the 50-nucleotide sequence that formed a positive-strand stem-loop structure identical to that of MHV-A59. These studies suggested that the RNA structure made by the internal sequence was important for positive-strand MHV RNA synthesis.

Analysis of cis-acting sequences essential for coronavirus defective interfering RNA replication

Mouse hepatitis virus (MHV) defective interfering (DI) RNA was used to determine the cis-acting sequences required for MHV RNA replication. A 2.2-kb-long cDNA clone of the MHV DI RNA DIssE was used to test the effect of deletions throughout the DI RNA on replication in DI RNA-transfected, MHV-infected cells. Data from a series of deletion mutants demonstrated that about 470 nucleotides at the 5' terminus, 460 nucleotides at the 3' terminus, and about 135 nucleotides in an internal position approximately 0.9 kb from the 5' end of DI RNA were necessary for DI RNA replication. These data suggested that cis-acting sequences which were necessary for MHV RNA replication required not only terminal sequences but also an internal sequence present at about 3.2 kb from the 5' end of the genome.

Modulation of doxorubicin efficacy in P388 leukemia following co-administration of verapamil in mini-osmotic pumps

Co-administration of doxorubicin and verapamil in Alzet mini-osmotic pumps increased the survival of B6D2F1 mice bearing the multidrug-resistant P388/ADR leukemia. A range of doxorubicin and verapamil combinations was studied to define dose-dependent efficacy and toxicity. High doses of doxorubicin (10 mg/kg/day) and verapamil (150 mg/kg/day) could be administered alone without any effect on survival. However, combining high doses of these two agents resulted in host toxicity. Doxorubicin doses of 1 to 10 mg/kg/day in combination with verapamil at 25-100 mg/kg/day were found to improve survival compared with either agent alone. Combination therapy also improved the survival of mice bearing the drug-sensitive P388/0 leukemia when compared to anthracycline treatment alone. The efficacy of the mini-osmotic pump delivery protocol was compared with other regimens delivering the same total cumulative dose of doxorubicin via repeated i.p. injections.

Generation and selection of coronavirus defective interfering RNA with large open reading frame by RNA recombination and possible editing

All of the coronavirus defective interfering (DI) RNAs analyzed thus far contain an open reading frame (ORF) from which DI RNA-specific protein(s) are translated, although the function of the DI-specific protein and the significance of the ORF are not known. A complete cDNA clone of a mouse hepatitis virus (MHV) DI RNA, NE-1, containing a single nucleotide deletion in the 5' region of the ORF was obtained and analyzed. Due to this single nucleotide deletion, a DI-specific protein of 7.5-kDa was made from NE-1, in contrast to the 88-kDa protein made from the wild-type DI RNA. NE-1 RNA was efficiently replicated after transfection into MHV-infected cells. However, after one passage of NE-1 RNA-containing virus, the 88-kDa wild-type protein was synthesized, indicating that the large ORF was restored during NE-1 DI RNA replication. Sequence analysis of NE-1 DI RNA from infected cells demonstrated that in approximately half of the DI RNA population, the ORF was restored by RNA recombination between NE-1 DI RNA and helper virus genomic sequence. The sequences of other DI RNAs contained an additional nontemplated A at the five-A sequence nine nucleotides upstream of the deletion site, resulting in a stretch of six consecutive As. In these "edited"-type DI RNAs, the original nucleotide deletion was maintained and no RNA recombination was observed. This "editing" produced an ORF of the same size as the wild-type DI RNA. We conclude that the DI RNA with a large ORF has a selective advantage. There was no significant difference in replication efficiency among these RNAs when they replicated alone. However, cotransfection of two DI RNA species and time course experiments suggested that homologous interference and other mechanism(s) during the early stage of virus multiplication are responsible for the accumulation of DI RNAs containing the large ORF.

Enhancement of the attachment on microcarriers and tPA production by fibroblast cells in a serum-free medium by the addition of the extracts of Centella asiatica

The addition of ethanol extracts of Centella asiatica showed a remarkable enhancement of fibroblast cells attachment to Cytodex beads in serum-free (SF) medium. It also improves tPA production in both batch and perfusion cultivations. The optimal concentration for SF medium was determined as 2 ppm of the extracts when using Cytodex III. In batch cultivation a high specific tPA production rate was obtained, compared to that from 5% FBS containing medium. However, a fast specific growth rate was observed in 5% FBS medium. In perfusion cultivation a reasonably good cell density and tPA production was achieved at a perfusion rate of 2.4 x 10(6) (viable cell/ml) and 0.65 (micrograms/ml), respectively at 22 ml/min.

Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation

The purpose of this study was to characterize the incidence and clinical features of accessory pathway recurrence after initially successful radiofrequency catheter ablation and to identify variables correlated with recurrence. Radiofrequency ablation was performed with a 7F deflectable tip catheter with a large (4 mm in length) distal electrode. Left-sided accessory pathways were approached through the left ventricle and right-sided pathways by way of the right atrium. Patients were included in the study if 1) they had an initially successful procedure, defined as the absence of accessory pathway conduction immediately after ablation, and 2) had undergone a 3-month follow-up electrophysiologic test or had documented recurrence of accessory pathway conduction. Accessory pathway conduction recurred after initially successful ablation in 16 (12%) of 130 patients. Almost half (7 of 16) of these recurrences were in the 1st 12 h after ablation, and the last occurred after 106 days. Return of delta waves on the electrocardiogram (ECG) or spontaneous paroxysmal supraventricular tachycardia was the initial indication of recurrence in 15 of the 16 patients. Two patients with manifest accessory pathways exhibited recurrence with exclusively concealed accessory pathway conduction. Accessory pathways ablated from the tricuspid anulus (right free wall or septal accessory pathways) had a much higher recurrence rate (24%) than did those on the mitral anulus (6%). Fourteen of 15 patients have had successful repeat accessory pathway ablation after the initial recurrence. After a mean follow-up period of 4 +/- 3 months, there have been no repeat recurrences of any of these accessory pathways. It is concluded that accessory pathway recurrence is infrequent after successful radiofrequency catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of typical to "atypical" atrioventricular nodal reentrant tachycardia after radiofrequency catheter modification of the atrioventricular junction

Typical atrioventricular (AV) nodal reentry tachycardia (AVNRT) is characterized by anterograde activation over a slowly conducting pathway and by retrograde activation through a rapidly conducting pathway. Preliminary reports suggest that radiofrequency catheter modification can eliminate typical AVNRT while preserving anterograde conduction. Radiofrequency catheter modification was used to treat 88 patients with typical AVNRT. After baseline electrophysiologic evaluation, the ablation catheter was positioned proximal and superior to the site of maximal His deflection. Radiofrequency energy was applied until there was significant attenuation of retrograde conduction, and elimination of AVNRT inducibility. Eighty-one patients were successfully treated and form the basis of this report. A new paroxysmal supraventricular tachycardia with RP greater than PR interval was induced at electrophysiologic testing after successful ablation in 9 patients (11%). Mean atrial-His activation time was 140 +/- 31 ms, and the ventriculoatrial activation time was 170 +/- 46 ms. This arrhythmia was induced only with ventricular pacing during isoproterenol infusion and appeared to be mediated by AV nodal reentry. New retrograde dual AV nodal physiology after modification was more frequent in patients with atypical tachycardia than in those without (4 of 9 vs 2 of 72; p less than 0.0001). Although none of the patients were treated, only 1 of 9 had an episode of spontaneous atypical tachycardia during a mean follow-up of 12 months. Results of this study confirm that typical AVNRT can be rendered noninducible without the complete destruction of reentrant pathways. Because induction of "atypical" AVNRT was not predictive of spontaneous arrhythmia recurrence, it should not be an indication for additional ablation sessions or long-term drug therapy.

Electrogram criteria for identification of appropriate target sites for radiofrequency catheter ablation of accessory atrioventricular connections

BACKGROUND

Catheter ablation of accessory atrioventricular (AV) connections using radiofrequency current has been demonstrated to be effective in the majority of patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory AV connection. However, electrogram criteria have not been established to guide attempts at radiofrequency catheter ablation.

METHODS AND RESULTS

The characteristics of local electrograms recorded at successful and unsuccessful sites of radiofrequency catheter ablation were determined in 132 patients. Electrograms recorded at a total of 438 sites were analyzed: 338 recorded during ablation of 90 manifest accessory AV connections and 100 recorded during ablation of 44 concealed accessory AV connections. During ablation of manifest accessory AV connections, the independent predictors of outcome were electrogram stability (p less than 0.001), the interval between activation of the ventricular electrogram and onset of the QRS complex (p less than 0.001), and the presence of an accessory AV connection potential (p less than 0.001). Radiofrequency energy delivery at sites demonstrating stable electrograms, a probable or possible accessory AV connection potential, and activation of the local ventrical electrogram before the onset of the QRS complex had a 57% probability of success compared with a 3% probability of success at sites without these features. During ablation of concealed accessory AV connections, the independent predictors of outcome were electrogram stability (p = 0.02), the presence of an accessory AV connection potential (p = 0.05), and the presence of retrograde continuous electrical activity (p = 0.04). Sites demonstrating a stable local electrogram, an accessory AV connection potential, and retrograde continuous electrical activity had an 82% probability of success compared with only a 5% probability of success at sites demonstrating none of these features.

CONCLUSIONS

The local electrogram parameters of greatest importance in predicting the success or failure of radiofrequency catheter ablation of accessory AV connections are electrogram stability, the presence of an accessory AV connection potential, and the timing of ventricular activation relative to the QRS complex (for manifest accessory AV connections) or retrograde continuous electrical activity (for concealed accessory AV connections). Awareness of these variables during attempts at radiofrequency catheter ablation of accessory AV connections may minimize the number of unnecessary applications of radiofrequency energy.

Impedance Monitoring During Radiofrequency Catheter Ablation in Humans

Radiofrequency catheter ablation of accessory pathways and the atrioventricular junction often requires multiple applications of energy. The inability to determine the effects of any given application on the underlying tissue may contribute to this problem. In the present study, impedance was monitored in 20 patients undergoing radiofrequency catheter ablation, and the relationship between an initial decrease in impedance and subsequent effects were examined. An initial fall in impedance of more than 10 omega was 78% sensitive and 88% specific for predicting subsequent evidence of tissue heating (interruption of conduction or an abrupt rise in impedance due to coagulum formation). In contrast, initial values of voltage, current, or impedance did not distinguish between effective and ineffective applications of radiofrequency energy. Continuous monitoring of impedance may facilitate radiofrequency catheter ablation.

Acute myocardial infarction in a patient with Buerger's disease. A case report and a review of the literature

A twenty-nine year old male smoker with a three year history of Buerger’s disease was admitted with excruciating precordial chest pain. The electrocardiogram indicated an anterior transmural infarction, and he also exhibited hypereosinophilia.

A coronary angiogram disclosed a partial segmental occlusion of the left anterior descending artery at the proximal portion. He was discharged without any complications after conservative managment.

Micellar liquid chromatography for the analysis of nucleosides and bases

A new high-performance liquid chromatographic method for the analysis of nucleosides and bases was developed in which a micellar mobile phase is used. Separation was achieved on a polyvinyl alcohol (PVA) column by isocratic elution with micellar sodium dodecyl sulfate (SDS) as the mobile phase. The retention behavior of the nucleosides and bases was significantly different from that obtained by reversed-phase chromatography. Effect of pH, temperature, and concentration of SDS and the counter ion (Na+) on retention behavior were investigated. With the PVA column, the best conditions for an isocratic separation were 0.01 M SDS (pH 3.4) and a flow-rate of 2 ml/min at ambient temperature. Mechanisms for the retention of the nucleosides and bases on the PVA column with a micellar mobile phase were proposed and an application of the separation was demonstrated by the analysis of human serum.