Management of Stroke in Patients With Chronic Liver Disease: A Practical Review

Chronic liver disease (CLD) is a highly prevalent condition. There is burgeoning recognition that there are many people with subclinical liver disease that may nonetheless be clinically significant. CLD has a variety of systemic aberrations relevant to stroke, including thrombocytopenia, coagulopathy, elevated liver enzymes, and altered drug metabolism. There is a growing body of literature on the intersection of CLD and stroke. Despite this, there have been few efforts to synthesize these data, and stroke guidelines provide scant guidance on this topic. To fill this gap, this multidisciplinary review provides a contemporary overview of CLD for the vascular neurologist while appraising data regarding the impact of CLD on stroke risk, mechanisms, and outcomes. Finally, the review addresses acute and chronic treatment considerations for patients with stroke-ischemic and hemorrhagic-and CLD.

Abstract TP74: Reducing Complications From Gastrostomy Tube Insertion In Stroke Patients - Quality Improvement Project At An Academic Tertiary Hospital

Introduction: Percutaneous gastrostomy tubes are frequently required for patients with strokes due to dysphagia, malnutrition, and intestinal dysmotility. Though generally well tolerated, delayed detection of complications following percutaneous gastrostomy tube insertion (including dislodgement, infection and bleeding) can lead to increased morbidity and mortality.

Methods: At a single academic tertiary hospital, a standardized protocol was instituted (September 2021) to enhance early detection and prevention of feeding tube complications on the neurology service, consisting predominantly of stroke patients. The protocol comprised of: 1) consistent documentation of feeding tube insertion by proceduralists, 2) universal abdominal binder application, 3) nursing driven delirium screening, 4) post procedural nursing assessment for high-risk feeding tube site changes, and 5) an escalation algorithm to address early complications. We compared rates of complications pre- (July 2020 - August 2021, 13 months) and post- (September 2021 - June 2022, 10 months) protocol implementation.

Results: A total of 103 gastrostomy tube insertions were reviewed (64 pre and 39 post protocol implementation). Overall complication rates decreased from 12.5% (N = 8 of 64; 3 dislodgements, 3 infections, 2 insertion site bleeding) to 2.5% (N = 1 of 39; 1 dislodgment) following the intervention. Mortality from complications decreased from 1.6% to 0%.

Conclusion: Complication rates of percutaneous gastrostomy tube placement may be reduced through implementation of standardized protocols on inpatient stroke patients. Further studies are warranted to assess its long-term effects and viability in other specialty services.

Improved Blood Suppression of Motion-Sensitized Driven Equilibrium in High-Resolution Whole-Brain Vessel Wall Imaging: Comparison of Contrast-Enhanced 3D T1-Weighted FSE with Motion-Sensitized Driven Equilibrium and Delay Alternating with Nutation for Tailored Excitation

BACKGROUND AND PURPOSE

High-resolution vessel wall MR imaging is prone to slow-flow artifacts, particularly when gadolinium shortens the T1 relaxation time of blood. This study aimed to determine the optimal preparation pulses for contrast-enhanced high-resolution vessel wall MR imaging.

MATERIALS AND METHODS

Fifty patients who underwent both motion-sensitized driven equilibrium and delay alternating with nutation for tailored excitation (DANTE) preparation pulses with contrast-enhanced 3D-T1-FSE were retrospectively included. Qualitative analysis was performed using a 4-grade visual scoring system for black-blood performance in the small-sized intracranial vessels, overall image quality, severity of artifacts, and the degree of blood suppression in all cortical veins as well as transverse sinuses. Quantitative analysis of the M1 segment of the MCA was also performed.

RESULTS

The qualitative analysis revealed that motion-sensitized driven equilibrium demonstrated a significantly higher black-blood score than DANTE in contrast-enhanced 3D-T1-FSE of the A3 segment (3.90 versus 3.58, P < .001); M3 (3.72 versus 3.26, P = .004); P2 to P3 (3.86 versus 3.64, P = .017); the internal cerebral vein (3.72 versus 2.32, P < .001); and overall cortical veins (3.30 versus 2.74, P < .001); and transverse sinuses (2.82 versus 2.38, P < .001). SNR_lumen, contrast-to noise ratio_wall-lumen, and SNR_wall in the M1 vessel were not significantly different between the 2 preparation pulses (all, P > .05).

CONCLUSIONS

Motion-sensitized driven equilibrium demonstrated improved blood suppression on contrast-enhanced 3D-T1-FSE in the small intracranial arteries and veins compared with DANTE. Motion-sensitized driven equilibrium is a useful preparation pulse for high-resolution vessel wall MR imaging to decrease venous contamination and suppress slow-flow artifacts when using contrast enhancement.

Accelerated Synthetic MRI with Deep Learning-Based Reconstruction for Pediatric Neuroimaging

BACKGROUND AND PURPOSE

Synthetic MR imaging is a time-efficient technique. However, its rather long scan time can be challenging for children. This study aimed to evaluate the clinical feasibility of accelerated synthetic MR imaging with deep learning-based reconstruction in pediatric neuroimaging and to investigate the impact of deep learning-based reconstruction on image quality and quantitative values in synthetic MR imaging.

MATERIALS AND METHODS

This study included 47 children 2.3-14.7 years of age who underwent both standard and accelerated synthetic MR imaging at 3T. The accelerated synthetic MR imaging was reconstructed using a deep learning pipeline. The image quality, lesion detectability, tissue values, and brain volumetry were compared among accelerated deep learning and accelerated and standard synthetic data sets.

RESULTS

The use of deep learning-based reconstruction in the accelerated synthetic scans significantly improved image quality for all contrast weightings (P < .001), resulting in image quality comparable with or superior to that of standard scans. There was no significant difference in lesion detectability between the accelerated deep learning and standard scans (P > .05). The tissue values and brain tissue volumes obtained with accelerated deep learning and the other 2 scans showed excellent agreement and a strong linear relationship (all, R 2 > 0.9). The difference in quantitative values of accelerated scans versus accelerated deep learning scans was very small (tissue values, <0.5%; volumetry, -1.46%-0.83%).

CONCLUSIONS

The use of deep learning-based reconstruction in synthetic MR imaging can reduce scan time by 42% while maintaining image quality and lesion detectability and providing consistent quantitative values. The accelerated deep learning synthetic MR imaging can replace standard synthetic MR imaging in both contrast-weighted and quantitative imaging.

Determining an infectious or autoimmune etiology in encephalitis

Objectives

Early presentation and workup for acute infectious (IE) and autoimmune encephalitis (AE) are similar. This study aims to identify routine laboratory markers at presentation that are associated with IE or AE.

Methods

This was a multi‐center retrospective study at three tertiary care hospitals in New York City analyzing demographic and clinical data from patients diagnosed with definitive encephalitis based on a confirmed pathogen and/or autoantibody and established criteria for clinical syndromes.

Results

Three hundred and thirty‐three individuals with confirmed acute meningoencephalitis were included. An infectious‐nonbacterial (NB) pathogen was identified in 151/333 (45.40%), bacterial pathogen in 95/333 (28.50%), and autoantibody in 87/333 (26.10%). NB encephalitis was differentiated from AE by the presence of fever (NB 62.25%, AE 24.10%; p < 0.001), higher CSF white blood cell (WBC) (median 78 cells/μL, 8.00 cells/μL; p < 0.001), higher CSF protein (76.50 mg/dL, 40.90 mg/dL; p < 0.001), lower CSF glucose (58.00 mg/dL, 69.00 mg/dL; p < 0.001), lower serum WBC (7.80 cells/μL, 9.72 cells/μL; p < 0.050), higher erythrocyte sedimentation rate (19.50 mm/HR, 13.00 mm/HR; p < 0.05), higher C‐reactive protein (6.40 mg/L, 1.25 mg/L; p = 0.005), and lack of antinuclear antibody titers (>1:40; NB 11.54%, AE 32.73%; p < 0.001). CSF‐to‐serum WBC ratio was significantly higher in NB compared to AE (NB 11.3, AE 0.99; p < 0.001). From these findings, the association of presenting with fever, CSF WBC ≥50 cells/μL, and CSF protein ≥75 mg/dL was explored in ruling‐out AE. When all three criteria are present, an AE was found to be highly unlikely (sensitivity 92%, specificity 75%, negative predictive value 95%, and positive predictive value 64%).

Interpretations

Specific paraclinical data at initial presentation may risk stratify which patients have an IE versus AE.

Abstract P255: Inpatient and Emergency Department Utilization for Herpes Zoster Infection After Stroke

Introduction: Patients with acute ischemic stroke (AIS) are generally vulnerable to subsequent infection, but there are few population-based data on the risk of herpes zoster infection after AIS. We tested the hypothesis that AIS is associated with an increased risk of zoster.

Methods: We performed a retrospective cohort study using statewide administrative claims data from all emergency department (ED) visits and admissions at nonfederal hospitals in Florida from 2005 to 2015 and New York from 2006 to 2015. These Healthcare Cost and Utilization Project data are well suited for longitudinal analyses of acute care utilization. The primary exposure was AIS, and the outcome was subsequent zoster; diagnoses were ascertained using validated ICD-9-CM codes. We excluded people with zoster before AIS. Survival statistics were used to calculate incidence rates, and Cox proportional hazards analysis was used to determine the association between AIS and subsequent ED visit or admission with zoster. In addition to demographics and comorbidities, models were adjusted for conditions associated with zoster (cancer and HIV/AIDS). In a secondary analysis, we limited the population to people under 50 years old, because current guidelines recommend zoster vaccination for only those at least 50 years old.

Results: Among 19,675,854 beneficiaries, 421,940 (2.1%) had AIS; their mean age was 70.8 (SD, 14.5) years. Follow-up duration was a mean of 4.1 (SD, 3.0) years. The incidence of zoster was 4.1 per 1000 patient-years in those with AIS and 2.1 per 1000 patient-years in those without. After AIS, the median time to zoster was 1.7 years (IQR, 0.4-4.1). In unadjusted models, patients with AIS had a two-fold higher risk of zoster (HR, 2.1; 95% CI, 2.0-2.1). AIS remained associated with zoster after adjusting for cardiopulmonary comorbidities and risk factors, medical comorbidities, tobacco and alcohol use, cancer, and HIV/AIDS (HR, 1.34; 95% CI, 1.30-1.39). This association was also observed in people under 50 years old (HR, 1.55; 95% CI, 1.31-1.84).

Conclusions: AIS is associated with an increased risk of subsequent ED and inpatient visit with zoster infection. Preventive strategies, including with currently available vaccinations, should be investigated.

Abstract P271: Influenza and Herpes Zoster Vaccination in United States Stroke Survivors: A Nationwide Analysis

Introduction: Patients with stroke face an increased risk of contracting influenza and herpes zoster. We compared vaccination rates in stroke survivors versus the general United States population.

Methods: We performed a cross-sectional analysis of data from the Centers for Disease Control and Prevention (CDC) Behavioral Risk Factor Surveillance System, which is an annual, nationally representative, health survey. Respondents are asked about medical conditions and care. We used the most recent years with complete data for influenza (2018) and zoster (2017). We utilized survey procedures to estimate CDC-recommended vaccination rates for influenza (annual vaccination for all) and zoster (one-time vaccination for those at least 50 years old). Multiple logistic regression was used to compare the odds of vaccination in those with and without prior stroke, while adjusting for demographics (including income and health insurance) and comorbidities that may influence vaccination rates (obesity, diabetes, heart disease, cancer, pulmonary disease, and smoking).

Results: In 2018, 8,254,136 (3.4%; 95% CI, 3.3-3.5) Americans were stroke survivors. The influenza vaccination rate was 44.4% (95% CI, 42.8-46.2) in stroke survivors and 32.8% (95% CI, 32.5-33.1) otherwise. In unadjusted models, stroke survivors were more likely to have had an influenza vaccination in the past year than those without stroke (OR, 1.6; 95% CI, 1.5-1.8). In 2017, 5,839,186 (5.7%; 95% CI, 5.5-5.9) Americans over 50 years old (i.e., eligible for zoster vaccination) were stroke survivors. The zoster vaccination rate was 30.3% (95% CI, 28.8-32.0) in stroke survivors and 27.6% (95% CI, 27.3-28.0) in those without prior stroke. Stroke survivors were more likely to have had zoster vaccination than those without stroke (OR, 1.14; 95% CI, 1.06-1.23). However, after accounting for demographics and comorbidities, stroke survivors were not more likely to be vaccinated for influenza (OR, 1.01; 95% CI, 0.93-1.10) or zoster (OR, 1.00; 95% CI, 0.90-1.12).

Conclusion: Stroke survivors were not vaccinated at higher rates than expected based on demographics and comorbidities, and absolute vaccination rates were low, especially for zoster. Efforts to increase vaccination after stroke may be needed.

Clinical Experience of 1-Minute Brain MRI Using a Multicontrast EPI Sequence in a Different Scan Environment

BACKGROUND AND PURPOSE

The long scan time of MR imaging is a major drawback limiting its clinical use in neuroimaging; therefore, we aimed to investigate the clinical feasibility of a 1-minute full-brain MR imaging using a multicontrast EPI sequence on a different MR imaging scanner than the ones previously reported.

MATERIALS AND METHODS

We retrospectively reviewed the records of 146 patients who underwent a multicontrast EPI sequence, including T1-FLAIR, T2-FLAIR, T2WI, DWI, and T2*WI sequences. Two attending neuroradiologists assessed the image quality of each sequence to compare the multicontrast EPI sequence with routine MR imaging protocols. We used the Wilcoxon signed rank test and McNemar test to compare the 2 MR imaging protocols.

RESULTS

The multicontrast EPI sequence generally showed sufficient image quality of >2 points using a 4-point assessment scale. Regarding image quality and susceptibility artifacts, there was no significant difference between the multicontrast EPI sequence DWI and routine DWI (P > .05), attesting to noninferiority of the multicontrast EPI, whereas there were significant differences in the other 4 sequences between the 2 MR imaging protocols.

CONCLUSIONS

The multicontrast EPI sequence showed sufficient image quality for clinical use with a shorter scan time; however, it was limited by inferior image quality and frequent susceptibility artifacts compared with routine brain MR imaging. Therefore, the multicontrast EPI sequence cannot completely replace the routine MR imaging protocol at present; however, it may be a feasible option in specific clinical situations such as screening, time-critical diseases or for use with patients prone to motion.

Individualized clinical management of patients at risk for Alzheimer's dementia

INTRODUCTION

Multidomain intervention for Alzheimer's disease (AD) risk reduction is an emerging therapeutic paradigm.

METHODS

Patients were prescribed individually tailored interventions (education/pharmacologic/nonpharmacologic) and rated on compliance. Normal cognition/subjective cognitive decline/preclinical AD was classified as Prevention. Mild cognitive impairment due to AD/mild-AD was classified as Early Treatment. Change from baseline to 18 months on the modified Alzheimer's Prevention Cognitive Composite (primary outcome) was compared against matched historical control cohorts. Cognitive aging composite (CogAging), AD/cardiovascular risk scales, and serum biomarkers were secondary outcomes.

RESULTS

One hundred seventy-four were assigned interventions (age 25-86). Higher-compliance Prevention improved more than both historical cohorts (P = .0012, P < .0001). Lower-compliance Prevention also improved more than both historical cohorts (P = .0088, P < .0055). Higher-compliance Early Treatment improved more than lower compliance (P = .0007). Higher-compliance Early Treatment improved more than historical cohorts (P < .0001, P = .0428). Lower-compliance Early Treatment did not differ (P = .9820, P = .1115). Similar effects occurred for CogAging. AD/cardiovascular risk scales and serum biomarkers improved.

DISCUSSION

Individualized multidomain interventions may improve cognition and reduce AD/cardiovascular risk scores in patients at-risk for AD dementia.

Clinical Feasibility of Zero TE Skull MRI in Patients with Head Trauma in Comparison with CT: A Single-Center Study

BACKGROUND AND PURPOSE

Conventional MR imaging techniques cannot produce optimal images of bone structures because bone has little water and a very short T2 life span. The aim of this study was to investigate the clinical feasibility of skull MR imaging using the zero TE sequence in patients with head trauma by assessing its diagnostic image quality and quantitative measurement compared with CT images.

MATERIALS AND METHODS

Thirteen enrolled patients with head trauma were assessed using brain CT and skull MR imaging. Image quality was graded on a 5-point Likert scale to compare the 2 modalities. To evaluate quantitative analyses between the 2 imaging modalities, we measured skull thickness and normalized bone tissue signal. Interobserver reliability was assessed using weighted κ statistics and the intraclass correlation coefficient.

RESULTS

Both imaging techniques clearly depicted skull fractures in all 13 patients. The mean scores for skull MR imaging and CT were 4.65 ± 0.56 and 4.73 ± 0.45 (P = .157), respectively, with substantial interobserver agreement (P < .05). The 2 imaging modalities showed no difference in skull thickness (P = .092) and had good correlation (r ² = 0.997). The mean value of normalized bone tissue signal among the 3 layers of the skull was relatively consistent (P = .401) with high interobserver agreement (P < .001).

CONCLUSIONS

Zero TE skull MR imaging has diagnostic image quality comparable with that of CT images. It also provides consistent results on the quantitative measurement of cortical bone with CT images.

The clinical practice of risk reduction for Alzheimer's disease: A precision medicine approach

Like virtually all age-related chronic diseases, late-onset Alzheimer's disease (AD) develops over an extended preclinical period and is associated with modifiable lifestyle and environmental factors. We hypothesize that multimodal interventions that address many risk factors simultaneously and are individually tailored to patients may help reduce AD risk. We describe a novel clinical methodology used to evaluate and treat patients at two Alzheimer's Prevention Clinics. The framework applies evidence-based principles of clinical precision medicine to tailor individualized recommendations, follow patients longitudinally to continually refine the interventions, and evaluate N-of-1 effectiveness (trial registered at ClinicalTrials.gov NCT03687710). Prior preliminary results suggest that the clinical practice of AD risk reduction is feasible, with measurable improvements in cognition and biomarkers of AD risk. We propose using these early findings as a foundation to evaluate the comparative effectiveness of personalized risk management within an international network of clinician researchers in a cohort study possibly leading to a randomized controlled trial.

Systematic thematic review of e-health research in the Gulf Cooperation Council (Arabian Gulf): Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and United Arab Emirates

Introduction The Gulf Cooperation Council (GCC or 'Arabian Gulf'), comprising Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and United Arab Emirates, is a political organization sharing a common history and culture. All GCC nations have made substantial investments in telecommunications and electronic health infrastructure since 2000. Methods We conducted a literature search in English and Arabic on peer-reviewed e-health research up to December 2014 originating in the GCC. The objective was to retrieve all research on e-health in the GCC and to categorize and analyse it qualitatively to reveal the current state of e-health research and development in the region. Inclusion criteria included peer-reviewed articles, books, book chapters, conference papers and graduate theses written on e-health in the GCC. Blogs, health websites and non-peer-reviewed literature were excluded. Results Three hundred and six articles were retrieved, categorized and analysed qualitatively to reveal the state of e-health research in the GCC. Both country-specific and GCC-wide major themes were identified using NVivo 10.0 qualitative software and summarized. The most common type of study was an overview (35.0%), with common study designs of case studies (26.8%) and descriptive articles (46.4%). Significant themes were: prospective national benefits from e-health, implementation and satisfaction with electronic health records, online technologies in medical education, innovative systems (case studies), and information security and personal health information. Discussion This is the first comprehensive analytical literature review of e-health in the GCC. Important research gaps were identified: few cost-benefit analyses, controlled interventional studies, or research targeting gender and religious issues were retrieved.

Metformin improves endothelial function in aortic tissue and microvascular endothelial cells subjected to diabetic hyperglycaemic conditions

The cellular mechanisms whereby metformin, the first line drug for type 2 diabetes (T2DM), mediates its antidiabetic effects remain elusive, particularly as to whether metformin has a direct protective action on the vasculature. This study was designed to determine if a brief 3-h exposure to metformin protects endothelial function against the effects of hyperglycaemia. We investigated the protective effects of metformin on endothelial-dependent vasodilatation (EDV) in thoracic aortae from T2DM db/db mice and on high glucose (HG, 40 mM) induced changes in endothelial nitric oxide synthase (eNOS) signaling in mouse microvascular endothelial cells (MMECs) in culture. Exposure of aortae from db+/? non-diabetic control mice to high glucose (HG, 40 mM) containing Krebs for 3-h significantly (P<0.05) reduced acetylcholine (ACh)-induced EDV compared to ACh-induced EDV in aortae maintained in normal glucose (NG, 11 mM) Krebs. The reduction of EDV was partially reversed following a 3-h exposure to 50 μM metformin; metformin also improved ACh-induced EDV in aortae from diabetic db/db mice. Immunoblot analysis of MMECs cultured in HG versus NG revealed a significant reduction of the ratio of phosphorylated (p-eNOS)/eNOS and p-Akt/Akt, but not the expression of total eNOS or Akt. The 3-h exposure of MMECs to metformin significantly (P<0.05) reversed the HG-induced reduction in phosphorylation of both eNOS and Akt; however, no changes were detected for phosphorylation of AMPK or the expression of SIRT1. Our data indicate that a 3-h exposure to metformin can reverse/reduce the impact of HG on endothelial function, via mechanisms linked to increased phosphorylation of eNOS and Akt.

Unintended consequences of policy change to watchful waiting for asymptomatic inguinal hernias

INTRODUCTION

In 2009 the Department of Health instructed McKinsey & Company to provide advice on how commissioners might achieve world class National Health Service productivity. Asymptomatic inguinal hernia repair was identified as a potentially cosmetic procedure, with limited clinical benefit. The Birmingham and Solihull primary care trust cluster introduced a policy of watchful waiting for asymptomatic inguinal hernia, which was implemented across the health economy in December 2010. This retrospective cohort study aimed to examine the effect of a change in clinical commissioning policy concerning elective surgical repair of asymptomatic inguinal hernias.

METHODS

A total of 1,032 patients undergoing inguinal hernia repair in the 16 months after the policy change were compared with 978 patients in the 16 months before. The main outcome measure was relative proportion of emergency repair in groups before and after the policy change. Multivariate binary logistic regression was used to adjust the main outcome for age, sex and hernia type.

RESULTS

The period after the policy change was associated with 59% higher odds of emergency repair (3.6% vs 5.5%, adjusted odds ratio [OR]: 1.59, 95% confidence interval [CI]: 1.03-2.47). In turn, emergency repair was associated with higher odds of adverse events (4.7% vs 18.5%, adjusted OR: 3.68, 95% CI: 2.04-6.63) and mortality (0.1% vs 5.4%, p<0.001, Fisher's exact test).

CONCLUSIONS

Introduction of a watchful waiting policy for asymptomatic inguinal hernias was associated with a significant increase in need for emergency repair, which was in turn associated with an increased risk of adverse events. Current policies may be placing patients at risk.

P3-04-04: Patterns of Distant Metastasis According to the Molecular Subtypes of Breast Cancer; Results of 529 Breast Cancer Patients

Backgrounds; Distant metastasis from breast cancer arises from various sites. But few studies concerning factors that can predict metastasis patterns in breast cancer has been reported. In this study, we analyzed the effect of breast cancer molecular subtypes on distant metastasis patterns and tried to determine factors that predict metastasis sites.

Patients and methods; From January 1995 to January 2004 at Yeungnam university hospital, patients diagnosed with the primary invasive breast cancer and received treatments were included in this study. Patients with bilateral breast cancer or distant metastasis at diagnosis were excluded. After analyzing estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), epidermal growth factor (EGFR) and cytokeratin (CK) 5/6 status, we classified patients into 5 categories, luminal A, luminal B, HER2−enriched, basal-like, and normal (triple negative nonbasal) breast cancers. Distant metastatic patterns of each category were analyzed.

Results; 529 patients were eligible for tissue microassay analysis and median follow-up period was 7.7 years. In this period, total 82 patients (15.5%) had locoregional relapse or distant metastasis and distant metastasis were identified in 54 patients (10.2%). Each distant metastatic rate was 10.5% (33/313) in luminal A, 8.7% (4/46) in luminal B, 10.2% (6/59) in HER2−enriched, 7.9% (7/89) in basal-like, and 18.2% (4/22) in normal subtype. Most frequent site of distant metastasis in all patients was bone and such result was consistent with Luminal A subtype. Liver metastasis was most frequent in Luminal B subtype, lung metastasis in HER2 enriched and normal subtype and brain metastasis in basal-like subtype.

P3-07-16: The Efficacy of Arm Node Preserving Surgery Using Axillary Reverse Mapping for Preventing Lymphedema in Patients with Breast Cancer

Background

Lymphedema affects over 20% of breast cancer patients undergoing axillary dissection. Axillary reverse mapping (ARM) technique to identify and preserve arm node during sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) was developed to prevent lymphedema. The purpose of this study was to investigate the location and the metastatic rate of the arm node, and finally to evaluate the short term incidence of lymphedema after arm node preserving surgery.

Patients and Methods

From January 2009 to October 2010, 97 breast cancer patients who underwent ARM were enrolled. 2.5ml blue dye was injected in ipsilateral upper inner arm. After at least 20 minutes after injection, SLNB or ALND was performed in the usual manner and blue stained arm nodes and/or lymphatics were identified. We checked arm circumference at baseline and average of 8.8 months after operation in ALND cases and 13.7 months in SLNB cases. Patients were divided into two groups, arm node preserved group (70 patients in ALND, 10 patients in SLNB) and unpreserved group (13 patients in ALND, 4 patients in SLNB). The difference of arm circumference between preoperative and postoperative was checked in these groups.

Results: The mean number of identified blue stained arm nodes was 1.4±0.6. The arm nodes were found in the inferolateral side of axillary and thoracodorsal vessels in 57 patients (58.76%), the inferomedial side in 37 patients (38.14%), the superolateral side in 2 patients (2.06%), and the superomedial side in 1 patient (1.04%). In the majority of patients (92%), arm nodes were located between the lower level of the axillary vein and just below the second intercostal brachial nerve.

In arm node unpreserved group, 2 patients had metastasis in their arm node. The one had a common pathway between the arm node and the sentinel lymph node. Another did not have a common pathway, but had extranodal extension with N3 metastasis. Among ALND patients, in arm node preserved group, the difference of arm circumference between preoperative and postoperative in ipsilateral and contralateral arm was 0.27cm and 0.07cm, respectively, whereas 0.47cm and −0.03cm in unpreserved group, and one lymphedema was found after 6 months. No difference was found between arm node preserved and unpreserved group amoung SLNB patients (0.21cm and 0.39cm in in preserved group, 0.2cm and 0.02cm in unpreserved group).

Idiopathic granulomatous mastitis: rare but important

A 61-year-old woman attended the breast clinic with unresolving mastitis and an associated mass, following failed treatment with antibiotics. Triple assessment confirmed idiopathic granulomatous mastitis. Unresponsive to further conservative management and steroid therapy, she underwent surgical excision and made uneventful recovery. No evidence of recurrence was detected at 18 months follow-up.

Limits on interactions between weakly interacting massive particles and nucleons obtained with CsI(Tl) crystal detectors

The Korea Invisible Mass Search (KIMS) experiment presents new limits on the weakly interacting massive particle (WIMP)-nucleon cross section using data from an exposure of 3409 kg.d taken with low-background CsI(Tl) crystals at the Yangyang Underground Laboratory. The most stringent limit on the spin-dependent interaction for a pure proton case is obtained. The DAMA signal region for both spin-independent and spin-dependent interactions for the WIMP masses greater than 20 GeV/c2 is excluded by the single experiment with crystal scintillators.

Site-directed mutagenesis evidence for a negatively charged trypsin inhibitory loop in sweet potato sporamin

Sporamin, a sweet potato tuberous storage protein, has trypsin inhibitory activity. Sequence comparison with other plant trypsin inhibitors (TIs) of the Kunitz family reveals that, instead of the conserved Arg or Lys found in other Kunitz TIs, sporamin contains a negatively charged residue (Asp70 or Glu72) at the P1 reactive site. Using site-directed mutagenesis, six mutants were generated containing substitutions at the reactive site and at one of the disulfide bonds, and the recombinant proteins were assayed for TI activity. Mutants Asp70Val and Glu72Arg were found to have only 2-3% of the wild-type activity. These results provide the first evidence for a negatively charged trypsin inhibitory loop and a new mechanism of trypsin inhibition in the Kunitz family.

Ataxia-telangiectasia: phenotype/genotype studies of ATM protein expression, mutations, and radiosensitivity

Previous studies on a limited number of ataxia-telangiectasia (A-T) patients with detectable levels of intracellular ATM protein have suggested a genotype/phenotype correlation. We sought to elucidate this possible correlation by comparing ATM protein levels with mutation types, radiosensitivity, and clinical phenotype. In this study, Western blot analysis was used to measure ATM protein in lysates of lymphoblastoid cell lines (LCLs) from 123 unrelated A-T patients, 10 A-T heterozygotes, and 10 patients with phenotypes similar to A-T. Our Western blot protocol can detect the presence of ATM protein in as little as 1 microg of total protein; at least 25 microg of protein was tested for each individual. ATM protein was absent in 105 of the 123 patients (85%); most of these patients had truncating mutations. The remaining subset of 18 patients (15%) had reduced levels of normal-sized ATM protein; missense mutations were more common in this subset. We used a colony survival assay to characterize the phenotypic response of the LCLs to radiation exposure; patients with or without detectable ATM protein were typically radiosensitive. Nine of 10 A-T heterozygotes also had reduced expression of ATM, indicating that both alleles contribute to ATM protein production. These data suggest that although ATM-specific mRNA is abundant in A-T cells, the abnormal ATM protein is unstable and is quickly targeted for degradation. We found little correlation between level of ATM protein and the type of underlying mutation, the clinical phenotype, or the radiophenotype.

Primary structure and function analysis of the Abrus precatorius agglutinin A chain by site-directed mutagenesis. Pro(199) Of amphiphilic alpha-helix H impairs protein synthesis inhibitory activity

Abrus agglutinin (AAG), a low-toxicity protein from the plant Abrus precatorius, is less lethal than abrina (ABRa) in mice (LD(50) = 5 mg/kg versus 20 microg/kg of body weight). Nucleotide sequence analysis of a cDNA clone encoding full-length AAG showed an open reading frame with 1641 base pairs, corresponding to a 547-amino acid residue preproprotein containing a signal peptide and a linker region (two amino acid residues) between the AAG-A and AAG-B subunits. AAG had high homology to ABRa (77.8%). The 13 amino acid residues involved in catalytic function, which are highly conserved among abrins and ricins, were also conserved within AAG-A. The protein synthesis inhibitory activity of AAG-A (IC(50) = 3.5 nM) was weaker than that of ABRa-A (0.05 nM). Molecular modeling followed by site-directed mutagenesis showed that Pro(199) of AAG-A, located in amphiphilic helix H and corresponding to Asn(200) of ABRa-A, can induce bending of helix H. This bending would presumably affect the binding of AAG-A to its target sequence, GpApGpAp, in the tetraloop structure of the 28 S rRNA subunit and could be one of the major factors contributing to the relatively weak protein synthesis inhibitory activity and toxicity of AAG.

Territrem B, a tremorgenic mycotoxin that inhibits acetylcholinesterase with a noncovalent yet irreversible binding mechanism

Territrem B (TRB) is a fungal metabolite isolated from Aspergillus terreus shown previously to be a potent and irreversible inhibitor of acetylcholinesterase (AChE). In the present study, a number of binding and inhibition assays were carried out to further characterize the inhibitory effect of TRB. The results indicate that the binding of TRB (a) is much more selective than a well characterized selective inhibitor of AChE, BW284C51, (b) adopts a one-to-one stoichiometry with the enzyme, (c) cannot be undone by an AChE-regenerating oxime agent, which contrasts the ability of 8 M urea to release AChE-bound TRB, (d) is enhanced by high concentration NaCl but prevented, unless preincubated, by Triton X-100, and (e) exhibits quasi-first order kinetics with an overall inhibition constant of 0.01 nM(-1) min(-1). Together these results suggest a very different irreversible binding (a noncovalent type) from that of the covalent type, which involves typical irreversible AChE inhibitors such as diisopropylfluorophosphate and neostigmine. According to the prediction of a molecular modeling study, the distinct AChE inhibitory characteristics of TRB may arise from the inhibitor being noncovalently trapped within a unique active-site gorge structure of the enzyme. It was predicted that an optimal TRB. AChE binding would position a narrowing connection of the TRB structure at a constricted area near the entrance of the gorge, thereby providing a structural basis for the observed irreversible binding.

Restraint-driven formation of alpha-helical coiled coils in molecular dynamics simulations

The alpha-helical coiled coil motif is among the first characterized and widely found architecture of protein structures. We report here a fast and reliable approach of simulated annealing molecular dynamics (SA/MD) for predicting the three-dimensional structures of various alpha-helical coiled coils of heptad repeat. One key element of our simulation involves a geometric restraint requiring residues occupying the first and fourth positions of the heptad to orient to the angle of their respective statistical average derived from a survey of coiled-coil structures deposited in the Protein Data Bank. Another is the incorporation of subunit rotation and inversion operations for generating symmetrized protein assemblies during the dynamics simulations. The procedure is fully automated and can be applied to different oligomerization states of identical subunits, as well as both parallel and antiparallel arrangements. Despite simplicity, the formation of five coiled-coil prototype systems driven by the restraint-based SA/MD approach shows that the level of prediction accuracy achieved previously by more elaborate procedures can be retained. The present work thus provides validation of a simulation approach that can be employed to utilize a wide variety of knowledge-based geometric restraints for structural prediction of symmetrical or pseudo-symmetrical protein systems.

The N terminus domain of type VI adenylyl cyclase mediates its inhibition by protein kinase C

Previous results from our laboratory have shown that phosphorylation of type VI adenylyl cyclase (ACVI) by protein kinase C (PKC) caused suppression of adenylyl cyclase activity. In the present study, we investigated the role of the N terminus cytosolic domain of ACVI in this PKC-mediated inhibition of ACVI. Removal of amino acids 1 to 86 of ACVI or mutation of Ser(10) (a potential PKC phosphorylation site) into alanine significantly relieved the PKC-mediated inhibition and markedly reduced the PKC-evoked protein phosphorylation. PKC also effectively phosphorylated a recombinant N terminus cytosolic domain (amino acids 1-160) protein of ACVI and a synthetic peptide representing Ser(10). In addition, the amino acids 1 to 86 truncated mutant exhibited kinetic properties similar to those of the wild type. Taken together, these data demonstrate that the highly variable N terminus cytoplasmic domain of ACVI is a regulatory domain with a critical role in PKC-mediated suppression, which is a hallmark of this adenylyl cyclase isozyme. In addition, Ser(10) was found to serve as an acceptor for the PKC-mediated phosphorylating transfer of ACVI.

Modeling helix-turn-helix protein-induced DNA bending with knowledge-based distance restraints

A crucial element of many gene functions is protein-induced DNA bending. Computer-generated models of such bending have generally been derived by using a presumed bending angle for DNA. Here we describe a knowledge-based docking strategy for modeling the structure of bent DNA recognized by a major groove-inserting alpha-helix of proteins with a helix-turn-helix (HTH) motif. The method encompasses a series of molecular mechanics and dynamics simulations and incorporates two experimentally derived distance restraints: one between the recognition helix and DNA, the other between respective sites of protein and DNA involved in chemical modification-enabled nuclease scissions. During simulation, a DNA initially placed at a distance was "steered" by these restraints to dock with the binding protein and bends. Three prototype systems of dimerized HTH DNA binding were examined: the catabolite gene activator protein (CAP), the phage 434 repressor (Rep), and the factor for inversion stimulation (Fis). For CAP-DNA and Rep-DNA, the root mean square differences between model and x-ray structures in nonhydrogen atoms of the DNA core domain were 2.5 A and 1.6 A, respectively. An experimental structure of Fis-DNA is not yet available, but the predicted asymmetrical bending and the bending angle agree with results from a recent biochemical analysis.

Complexation of Metal Ions with Amphiphilic o,o'-Dihydroxyazobenzene Derivatives at the Air/Water Interface

The effect of metal salts (FeCl3, FeCl2, CuCl2, CoCl2, and [Co(NH3)5Cl]Cl2) on the surface pressure-area isotherm of an o,o'-dihydroxyazobenzene-containing amphiphile was investigated. The isotherm of the amphiphile was little affected in the presence of CuCl2 and [Co(NH3)5Cl]Cl2, but the isotherm was greatly affected by the presence of FeCl3, FeCl2, and CoCl2, implying the formation of certain complexes at the air/water interface. In the presence of salts in the water subphase, Y-type Langmuir-Blodgett (LB) multilayers could be readily assembled on the arachidic acid precoated solid substrates. From UV/Vis and ATR-IR spectroscopy, the coordinative polymerization of the azobenzene moieties was evidenced to occur when the Fe3+, Fe2+, Cu2+, and Co2+ ions were present in the water subphase. The long axis of the azobenzene moiety seemed in all LB films to assume a nearly perpendicular orientation with respect to the solid substrate, but the orientation of the C&dbond;O bond appeared obviously different between the films prepared in the presence of FeCl3 and CuCl2. The IR spectral data indicated further that the alkyl chains in the LB film prepared in the presence of CuCl2 assumed a more close-packed structure than those prepared in the presence of FeCl3, along with an orientation 10 degrees more tilted in the former than in the latter with respect to the surface normal. Copyright 1999 Academic Press.

VHMPT: a graphical viewer and editor for helical membrane protein topologies

MOTIVATION

Lacking structures resolved at atomic resolution, the great majority of membrane proteins have typically been depicted in a schematic two-dimensional (2D) topology consisting of putative transmembrane domains predicted from hydropathy plots. As more and more sequences of membrane proteins become available from genome projects, there is a need to automate the process of generating the schematic topology while allowing important information, such as the individual amino acid and the extent to which it is conserved in evolution, to be conveniently inspected. We addressed this need by developing a program called VHMPT.

RESULTS

VHMPT (a graphical V iewer and editor for H elical line M embrane P rotein T opologies) can automatically generate a schematic 2D topology for a protein with transmembrane helices. Through an interactive graphical interface, VHMPT allows users to modify the layout of the generated topology, label specific amino acid or amino acid groups, and annotate with arrows and texts. Given a multiple sequence alignment file, VHMPT can also color code a normalized conservation score for each amino acid on the generated topology, allowing ready visual recognition of highly conserved (or variable) topological regions. VHMPT is written in Tcl/Tk and can run on platforms that have installed the Tcl/Tk interpreter.

AVAILABILITY

The source code and a user manual for VHMPT are available for download at http://www. ibms.sinica.edu.tw/mjhwang/vhmpt.

CONTACT

mjhwang@mail.ibms.sinica.edu.tw

New insights for dinucleotide backbone binding in conserved C5'-H . . . O hydrogen bonds

Most enzymes that utilize dinucleotide NAD or NADP are known to comprise a glycine-rich loop segment (e.g. the GXGXXG signature motif of Rossman fold) which binds the cofactor's diphosphate moiety. Through analysis of a set of diverse NAD(P)-bound protein structures, we show here that with few exceptions this diphosphate binding is complemented by a second loop segment interacting from a different angle with unconventional yet apparently ubiquitous C-HellipsisO hydrogen bonds formed between C5' methylene of dinucleotide and, primarily, carbonyl oxygen of protein. This finding implicates an important role of C5' in protein-nucleotide recognition.

Estimates of relative binding free energies for HIV protease inhibitors using different levels of approximations

Although the free energy perturbation approach is a rigorous method for estimating the relative binding free energy between an enzyme and its inhibitors, it is computationally expensive. This paper examines the accuracy at different levels of approximations, following the series expansion of free energy derived by Aqvist et al. Level-0 calculates only the enzyme-inhibitor interaction energy at the minimum energy configuration without solvent. In Level-0MD, the inhibitor configurations are sampled by molecular dynamics. These levels assume that the second- and higher order terms in the series expansion can be neglected and that the interaction energies in the bound and unbound states are equal. Level-1 does not assume equal interaction energies in the bound and unbound states. Level-1S includes the solvent contribution but both enzyme and inhibitor are fixed. In Level-1SMD, the inhibitor configurations are sampled by molecular dynamics. Level-2SMD retains the second-order term. We chose seven HIV-1 protease inhibitors for study: A77003, A76889, A76928, A78791, A74704, JG365 and MVT101. Level-0 and Level-0MD were found to give essentially the same relative interaction energies by using the AMBER force field, suggesting that fixing atomic positions may be a good approximation in some cases. However, as expected, Level-0 or Level-0MD gave poor predictions for the relative binding free energies between hydrophobic inhibitors (e.g. A77003) and more hydrophilic inhibitors (e.g. JG365). Level-1SMD produced a much better correlation between calculated and experimental results. Inclusion of the second-order term did not improve the accuracy.

Derivation of class II force fields. VI. Carbohydrate compounds and anomeric effects

The methodology for deriving class II force fields has been applied to acetal, hemiacetal, and carbohydrate compounds. A set of eighteen model compounds containing one or more anomeric centers was selected for generating the quantum mechanical energy surface, from which the force field was derived and the functional form assessed. The quality of the fit was tested by comparing the energy surface predicted by the force field with ab initio results. Structural, energetic, and dynamic properties (vibrational frequencies) were analyzed. In addition, alpha and beta anomeric equilibrium structures and energies of 2-methoxytetrahydropyran, 2-deoxyribose, and glucose were computed at the HF/6-31G* and higher ab initio levels. These calculations provide test data from molecules outside the training set used to derive the force field. The quantum calculations were used to assess the ability of the class II force field and two quadratic diagonal (class I) force fields, CVFF, and Homans' extension of the AMBER force field, to account for the anomeric effects on the structural and energetic properties of carbohydrate systems. These class I force fields are unable to account for observed structural and energetic trends, exhibiting deviations as large as 5 kcal/mol in relative energies. The class II force field, on the other hand, is shown to reproduce anomeric structural as well as energetic differences. An energy component analysis of this force field shows that the anomeric differences are dominated by torsional energies, although coupling terms, especially angle/torsion, also make significant contributions (roughly 1 kcal/mol in glucose). In addition, the force field accurately accounts for both anomeric and exo-anomeric energy differences in 2-methoxytetrahydropyran, and anomeric energy differences in 2-deoxyribose and glucose.

Shaker pore structure as predicted by annealed atomic simulation using symmetry and novel geometric restraints

Recent studies making use of channel-blocking peptides as molecular calipers have revealed the architecture of the pore-forming region of Shaker-type potassium channels. Here we show that the low-resolution, experimentally derived geometric information can be incorporated as restraints within the context of an annealed molecular dynamics simulation to predict an atomic structure for the channel pore which, by virtue of restraints, conforms to the experimental evidence. The simulation is reminiscent of the computational method employed by nuclear magnetic resonance (NMR) spectroscopists to resolve solution structures of biological macromolecules, but in lieu of restraints conventionally derived from NMR spectra, novel restraints are developed that include side-chain orientation of amino acid residues and assumed symmetry of protein subunits. The method presented here offers the possibility of expanding cooperation between simulation and experiment in developing structural models, especially for systems such as ion channels whose three-dimensional structures may not be amenable to determination by direct methods at the present time.

A model for Fis N-terminus and Fis-invertase recognition

In this modeling, we show that the elusive Fis N-terminus involved in invertase-mediated site-specific DNA inversion is, by all indications, a hinged flapping loop. The prediction is based on a combined sequence and secondary structure alignment against known structures of protein segments, as well as a tetrapeptide fragment observed crystallographically. Its validity is strongly supported by the ability to interpret consistently the available mutagenesis data pertaining to this region including, especially, a series of deletion mutants which until this work had been a puzzle in the search for structural explanations. A model for Fis-invertase recognition is also proposed.