Cannabis use in the United States and its impact on gastrointestinal health

In recent years, the legalization and social acceptability of cannabis use have increased in the United States. Concurrently, the prevalence of cannabis use has continued to rise, and cannabis products have diversified. There are growing concerns regarding the health effects of regular and high-potency cannabis use, and new research has shed light on its potentially negative effects. Here, we review evidence of the gastrointestinal (GI) effects of cannabis and cannabinoids. Dysregulation of the endocannabinoid system might contribute to various GI disorders, including irritable bowel syndrome and cyclic vomiting syndrome, and endocannabinoids have been found to regulate visceral sensation, nausea, vomiting, and the gut microbiome. Cannabis has been shown to have antiemetic properties, and the US Food and Drug Administration has approved cannabis-based medications for treating chemotherapy-induced nausea and vomiting. Yet, chronic heavy cannabis use has been linked to recurrent episodes of severe nausea and intractable vomiting (cannabinoid hyperemesis syndrome). Given the considerable heterogeneity in the scientific literature, it is unclear if cannabinoid hyperemesis syndrome is truly a distinct entity or a subtype of cyclic vomiting that is unmasked by heavy cannabis use and the associated dysregulation of the endocannabinoid system. The changes in cannabis legalization, availability, and public risk perceptions have outpaced research in this area and there is a need for robust, prospective, large-scale studies to understand the effects of cannabis use on GI health.

The impact of bariatric surgery on admissions for gastrointestinal complications and conditions associated with obesity: A nationwide study

BACKGROUND

Obesity worsens various gastrointestinal pathologies. While bariatric surgery ameliorates obesity, it substantially modifies the gastrointestinal system depending on surgery type, with limited data on subsequent impact on obesity-related gastrointestinal admissions.

METHODS

Using the 2012-2014 Nationwide Readmission Database, we included individuals with obesity who received vertical sleeve gastrectomy (VSG), Roux-en-Y gastric bypass (RYGB), or hernia repair (HR-control surgery). Our main focus was the adjusted odds ratio (aOR) for gastrointestinal inpatient admissions within 6 months following surgery compared to the 6 months preceding it, while controlling for several confounding factors. Gastrointestinal admissions were grouped into postoperative complications or obesity-associated gastrointestinal conditions.

RESULTS

Our cohort included 140,103 adults with RYGB, 132,253 with VSG, and 12,436 HR controls. Postoperative gastrointestinal complications were most common after RYGB, prominently obstruction (aOR = 33.17, 95%CI: 18.01, 61.10), and Clostridium difficile infection (aOR: 12.52, 95%CI: 6.22, 25.19). VSG also saw significantly increased but less frequent similar conditions. Notably, for gastrointestinal conditions associated with obesity, acute pancreatitis risk was higher post-VSG (aOR = 6.26, 95%CI: 4.02, 9.73). Post-RYGB patients were most likely to be admitted for cholelithiasis with cholecystitis (aOR: 4.15, 95% CI: 3.24, 5.31), followed by chronic liver disease (aOR: 3.00, 95% CI: 2.33, 3.87). The risk of noninfectious colitis admissions was threefold higher after RYGB and VSG. No gastrointestinal conditions showed an increase after HR.

CONCLUSION

Despite weight loss, bariatric surgery was associated with an increased risk of hepato-pancreatobiliary and colitis admissions related to obesity in the first six postoperative months, with considerable variations in rates of gastrointestinal conditions by surgery type.

Pharmacogenomic testing for CYP2C19 and CYP2D6 in cyclic vomiting syndrome

BACKGROUND

Amitriptyline (AT) is recommended as first-line prophylactic therapy in patients with cyclic vomiting syndrome (CVS). However, significant side effects limit its use and dosing is based on trial and error. Though the Clinical Pharmacogenetic Implementation Consortium (CPIC) Guidelines recommend dosing for AT based on CY2D6 and CYP2C19 genotype profile, this is not followed in clinical practice.

METHODS

This pilot study determined CYP2C19 and CYP2D6 genotypes and ascertained its association with adverse drug reactions (ADRs), clinical response, and serum concentration of AT and nortriptyline in a well-characterized cohort of adults with CVS.

KEY RESULTS

Of 46 subjects with CVS, age 33 ± 12 years, 61% female, 85% Caucasian, a third (33%) had normal CYP2C19 metabolizer status, while 4% were poor, and 43% were ultrarapid metabolizers. Most (61%) had normal CYP2D6 genotype while 9% were poor and 2% were ultra-rapid metabolizers. There was no statistically significant association between genotype and ADRs, clinical response or serum drug concentration. There was a trend towards significance between genotype and clinical response, with 64% of responders having normal CYP2D6 metabolism versus 36% of nonresponders (p = 0.06). ADRs were encountered in 46% of patients with 28% discontinuing the medication as a result.

CONCLUSIONS AND INFERENCES

A subset of patients with CVS have dysfunctional alleles of CYP2C19 and CYP2D6. Larger prospective studies to evaluate the clinical impact of pharmacogenomic testing in CVS are needed. This has the potential to optimize clinical management, predict ADRs and allow for personalized therapy.

Improving the Diagnostic Yield of High-Resolution Esophageal Manometry for GERD: The "Straight Leg-Raise" International Study

BACKGROUND & AIMS

The straight leg raise (SLR) maneuver during high-resolution manometry (HRM) can assess esophagogastric junction (EGJ) barrier function by measuring changes in intraesophageal pressure (IEP) when intra-abdominal pressure is increased. We aimed to determine whether increased esophageal pressure during SLR predicts pathologic esophageal acid exposure time (AET).

METHODS

Adult patients with persistent gastroesophageal reflux disease (GERD) symptoms undergoing HRM and pH-impedance or wireless pH study off proton pump inhibitor were prospectively studied between July 2021 and March 2022. After the HRM Chicago 4.0 protocol, patients were requested to elevate 1 leg at 45º for 5 seconds while supine. The SLR maneuver was considered effective when intra-abdominal pressure increased by 50%. IEPs were recorded 5 cm above the lower esophageal sphincter at baseline and during SLR. GERD was defined as AET greater than 6%.

RESULTS

The SLR was effective in 295 patients (81%), 115 (39%) of whom had an AET greater than 6%. Hiatal hernia (EGJ type 2 or 3) was seen in 135 (46%) patients. Compared with patients with an AET less than 6%, peak IEP during SLR was significantly higher in the GERD group (29.7 vs 13.9 mm Hg; P < .001). Using receiver operating characteristic analysis, an increase of 11 mm Hg of peak IEP from baseline during SLR was the optimal cut-off value to predict an AET greater than 6% (area under the receiver operating characteristic curve, 0.84; sensitivity, 79%; and specificity, 85%), regardless of the presence of hiatal hernia. On multivariable analysis, an IEP pressure increase during the SLR maneuver, EGJ contractile integral, EGJ subtype 2, and EGJ subtype 3, were found to be significant predictors of AET greater than 6% CONCLUSIONS: The SLR maneuver can predict abnormal an AET, thereby increasing the diagnostic value of HRM when GERD is suspected.

CLINICALTRIALS

gov ID: NCT04813029.

Esophageal Dysfunction in Post-lung Transplant: An Enigma

The prevalence of lung transplants has increased over the years, albeit with a low survival rate amongst all solid organ transplants, including liver and heart transplantation. Microaspiration is one of the primary mechanisms that has been implicated in the pathogenesis of lung injury following lung transplants. Of late, esophageal dysfunction such as gastroesophageal reflux and esophageal hypercontractility is often noted post-lung transplant. However, reflux is associated with chronic allograft lung injury such as bronchiolitis obliterans syndrome, which is one of the predictors for long-term survival in this specialized population. Its role in acute lung injury post-lung transplant is still being explored. This review critically examines the salient points which provide the current understanding of the characteristics, pathophysiology, and implications of esophageal dysfunction following lung transplant.

Predictors of Early Readmissions in Hospitalized Patients With Gastroparesis: A Nationwide Analysis

Background/Aims

Gastroparesis is a chronic gastrointestinal disorder that frequently presents with symptoms that are difficult to manage, necessitating frequent hospitalizations. We sought to determine the predictors of early readmission due to gastroparesis based on etiology.

Methods

We identified all adults discharged with a principal diagnosis of gastroparesis after hospitalization from the 2014 Nationwide Readmission Database. We compared etiology wise (diabetes, post-surgical, and idiopathic) early readmission. Multivariate regression analyses were performed to identify significant predictors of 30-day readmission.

Results

A total of 12 689 patients were identified, 30.7% diabetic, 2.6% post-surgical, and 66.7% were idiopathic. Patients with diabetic gastroparesis were more likely to be readmitted within 30 days than idiopathic (adjusted odds ratio [aOR], 0.81; 95% confidence interval [CI], 0.69-0.94) and post-surgical gastroparesis (aOR, 0.58; 95% CI, 0.34-0.98). Pyloroplasty was associated with less likelihood of 30-day readmission (aOR, 0.45; 95% CI, 0.20-0.97). In addition, male gender (aOR, 1.18; 95% CI, 1.02-1.37), modified Elixhauser comorbidity score ≥ 3 (aOR, 1.38; 95% CI, 1.18-1.61), chronic pain syndrome (aOR, 1.41; 95% CI, 1.11-1.78), younger (18-64 years) age (aOR, 1.64; 95% CI, 1.34-2.00), need for percutaneous endoscopic gastrostomy/jejunostomy tube (aOR, 2.06; 95% CI, 1.21-3.52), and need for total parenteral nutrition (aOR, 1.70; 95% CI, 1.24-2.35) were associated with increased risk of 30-day readmission.

Conclusions

One in 5 patients was readmitted with gastroparesis within 30 days. In the diabetic group, diabetes-related complications contributed to readmissions than gastroparesis. Pyloroplasty is associated with reduced early hospital readmission. Prospective studies are needed for validation of these results.

Excess Volatility in Bitcoin: Extreme Value Volatility Estimation

This article investigates the excess volatility in Bitcoin prices using an unbiased extreme value volatility estimator. We capture the time-varying nature of the excess volatility using bootstrap, multi-horizon, sub-sampling and rolling-window approaches. We observe that Bitcoin price changes are almost efficient. Although Bitcoin prices exhibit high volatility and show signs of excess volatility for a few periods, it is decreasing over time. After controlling for the outliers, we also notice that the Bitcoin market shows signs of increasing maturity. Overall, Bitcoin prices show a sign of increasing efficiency with decreasing volatility. Our findings have implications for investors making investment decisions and for regulators making policy choices.

Hospital outcomes and early readmission for the most common gastrointestinal and liver diseases in the United States: Implications for healthcare delivery

BACKGROUND

Gastrointestinal (GI) and liver diseases contribute to substantial inpatient morbidity, mortality, and healthcare resource utilization. Finding ways to reduce the economic burden of healthcare costs and the impact of these diseases is of crucial importance. Thirty-day readmission rates and related hospital outcomes can serve as objective measures to assess the impact of and provide further insights into the most common GI ailments.

AIM

To identify the thirty-day readmission rates with related predictors and outcomes of hospitalization of the most common GI and liver diseases in the United States.

METHODS

A cross-sectional analysis of the 2012 National Inpatient Sample was performed to identify the 13 most common GI diseases. The 2013 Nationwide Readmission Database was then queried with specific International Classification of Diseases, Ninth Revision, Clinical Modification codes. Primary outcomes were mortality (index admission, calendar-year), hospitalization costs, and thirty-day readmission and secondary outcomes were predictors of thirty-day readmission.

RESULTS

For the year 2013, the thirteen most common GI diseases contributed to 2.4 million index hospitalizations accounting for about $25 billion. The thirty-day readmission rates were highest for chronic liver disease (25.4%), Clostridium difficile (C. difficile) infection (23.6%), functional/motility disorders (18.5%), inflammatory bowel disease (16.3%), and GI bleeding (15.5%). The highest index and subsequent calendar-year hospitalization mortality rates were chronic liver disease (6.1% and 12.6%), C. difficile infection (2.3% and 6.1%), and GI bleeding (2.2% and 5.0%), respectively. Thirty-day readmission correlated with any subsequent admission mortality (r = 0.798, P = 0.001). Medicare/Medicaid insurances, ≥ 3 Elixhauser comorbidities, and length of stay > 3 d were significantly associated with thirty-day readmission for all the thirteen GI diseases.

CONCLUSION

Preventable and non-chronic GI disease contributed to a significant economic and health burden comparable to chronic GI conditions, providing a window of opportunity for improving healthcare delivery in reducing its burden.

Treatment of gastrointestinal bleeding in left ventricular assist devices: A comprehensive review

Left ventricular assist devices (LVAD) are increasingly become common as life prolonging therapy in patients with advanced heart failure. Current devices are now used as definitive treatment in some patients given the improved durability of continuous flow pumps. Unfortunately, continuous flow LVADs are fraught with complications such as gastrointestinal (GI) bleeding that are primarily attributed to the formation of arteriovenous malformations. With frequent GI bleeding, antiplatelet and anticoagulation therapies are usually discontinued increasing the risk of life-threatening events. Small bowel bleeds account for 15% as the source and patients often undergo multiple endoscopic procedures. Treatment strategies include resuscitative measures and endoscopic therapies. Medical treatment is with octreotide. Novel treatment options include thalidomide, angiotensin converting enzyme inhibitors/angiotensin II receptor blockers, estrogen-based hormonal therapies, doxycycline, desmopressin and bevacizumab. Current research has explored the mechanism of frequent GI bleeds in this population, including destruction of von Willebrand factor, upregulation of tissue factor, vascular endothelial growth factor, tumor necrosis factor-α, tumor growth factor-β, and angiopoetin-2, and downregulation of angiopoetin-1. In addition, healthcare resource utilization is only increasing in this patient population with higher admissions, readmissions, blood product utilization, and endoscopy. While some of the novel endoscopic and medical therapies for LVAD bleeds are still in their development stages, these tools will yet be crucial as the number of LVAD placements will likely only increase in the coming years.

Materials informatics for the screening of multi-principal elements and high-entropy alloys

The field of multi-principal element or (single-phase) high-entropy (HE) alloys has recently seen exponential growth as these systems represent a paradigm shift in alloy development, in some cases exhibiting unexpected structures and superior mechanical properties. However, the identification of promising HE alloys presents a daunting challenge given the associated vastness of the chemistry/composition space. We describe here a supervised learning strategy for the efficient screening of HE alloys that combines two complementary tools, namely: (1) a multiple regression analysis and its generalization, a canonical-correlation analysis (CCA) and (2) a genetic algorithm (GA) with a CCA-inspired fitness function. These tools permit the identification of promising multi-principal element alloys. We implement this procedure using a database for which mechanical property information exists and highlight new alloys having high hardnesses. Our methodology is validated by comparing predicted hardnesses with alloys fabricated by arc-melting, identifying alloys having very high measured hardnesses.

The identification of high entropy alloys is challenging given the vastness of the compositional space associated with these systems. Here the authors propose a supervised learning strategy for the efficient screening of high entropy alloys, whose hardness predictions are validated by experiments.

Efficient nitrogen-vacancy centers' fluorescence excitation and collection from micrometer-sized diamond by a tapered optical fiber in endoscope-type configuration

Using an optical fiber to both excite the nitrogen-vacancy (NV) center in diamond and collect its fluorescence is essential to build NV-based endoscope-type sensor. Such endoscope-type sensor can reach inaccessible fields for traditional NV-based sensors built by bulky optical components and extend the application areas. Since single NV's fluorescence is weak and can easily be buried in fluorescence from optical fiber core's oxide defects excited by the green laser, fixing a micrometer size diamond containing high-density NVs rather than a nanodiamond containing single NV or several NVs on the apex of an optical fiber to build an endoscope-type sensor is more implementable. Unfortunately, due to small numerical aperture (NA), most of the optical fibers have a low fluorescence collection efficiency, which limits the sensitivity and spatial resolution of the NV-based endoscope-type sensor. Here, using a tapered optical fiber (TOF) tip, we significantly improve the efficiency of the laser excitation and fluorescence collection of the NV ensembles in diamond. This could potentially enhance the sensitivity and spatial resolution of the NV-based endoscope-type sensor. Numerical calculations show that the TOF tip delivers a high NA and has a high NV excitation and fluorescence collection efficiency. Experiments demonstrate that such TOF tip can obtain up to over 7-fold excitation efficiency and over 15-fold fluorescence collection efficiency of that from a flat-ended fiber (non-TOF) tip.

Swallow strength training exercise for elderly: A health maintenance need

BACKGROUND

Recent studies have shown high prevalence of oropharyngeal dysphagia associated with frailty- and age-related muscle weakness. Strength training exercises have been advocated for locomotive health maintenance in the elderly and have shown positive outcomes. As muscles involved in oropharyngeal phase of swallowing are also comprised of striated muscles, the aim of this study was to determine biomechanical effect of a novel resistance exercise program, Swallowing Against Laryngeal Restriction (SALR), on pharyngeal phase swallowing in the healthy elderly.

METHODS

A total of 28 volunteers (75 + 7 years; 17 females) with no complaint of dysphagia were studied using video fluoroscopy before and after 6 weeks of the swallow strength training exercise. Eighteen of these volunteers also underwent high-resolution pharyngeal manometry non-concurrent with fluoroscopy. Ten additional volunteers (81 + 6 years; 9 females) were studied by videofluoroscopy before and after 6 weeks of a sham exercise.

KEY RESULTS

Swallow resistance exercise but not the sham exercise resulted in a significant increase in maximum upper esophageal sphincter opening (P < .01), superior and anterior laryngeal excursion (P < .01) as well as posterior pharyngeal wall thickness (P < .01). Resistance exercise but not sham exercise also resulted in a significant increase in deglutitive pharyngeal contractile integral (P < .01).

CONCLUSIONS & INFERENCES

Strength training of muscles involved in the pharyngeal phase of swallowing using the swallowing against laryngeal restriction technique is feasible and significantly improves key physiologic features of the pharyngeal phase of swallowing. These findings provide the basis for consideration of developing an exercise-based swallow health maintenance program for the elderly swallow health maintenance program for the elderly.

Defining pharyngeal contractile integral during high-resolution manometry in neonates: a neuromotor marker of pharyngeal vigor

BACKGROUND

Pharyngeal contractility is critical for safe bolus propulsion. Pharyngeal contractile vigor can be measured by Pharyngeal Contractile Integral (PhCI): product of mean pharyngeal contractile amplitude, length, and duration. We characterized PhCI in neonates and examined the hypothesis that PhCI differs with mode of stimulation.

METHODS

Nineteen neonates born at 38.6 (34-41) weeks gestation were evaluated at 42.9 (40.4-44.0) weeks postmenstrual age using high-resolution manometry (HRM). PhCI was calculated using: (a) Conventional and (b) Automated Swallow Detection algorithm (ASDA) methods. Contractility metrics of all pharyngeal regions were examined using mixed statistical models during spontaneous and adaptive state (pharyngeal and oral stimulus) swallowing.

RESULTS

PhCI of oral stimuli swallows were distinct from pharyngeal stimuli and spontaneous swallows (P < 0.05). Correlation between conventional and ASDA methods was high (P < 0.001). PhCI increased with swallows for pharyngeal stimulation (P < 0.05) but remained stable for swallows with oral stimulation. PhCI differed between proximal and distal pharynx (P < 0.001).

CONCLUSIONS

PhCI is a novel reliable metric capable of distinguishing (1) proximal and distal pharyngeal activity, (2) effects of oral and pharyngeal stimulation, and (3) effects of prolonged stimulation. Changes in pharyngeal contractility with maturation, disease, and therapies can be examined with PhCI.

Characterization of pharyngeal peristaltic pressure variability during volitional swallowing in healthy individuals

BACKGROUND

Recent technological advances incorporated in high resolution manometry have justifiably heightened interest in manometric evaluation of the pharynx. Despite this interest, from both physiologic and clinical perspective there remain a number of unanswered questions regarding the magnitude of variability of pharyngeal pressure phenomena. Therefore, the aim of the present study was to characterize in healthy individuals the inter-subject and recording-site specific variability of pharyngeal peristaltic pressure phenomena.

METHODS

We studied 32 healthy subjects (age: 21-83 years,20 under 35 years) during dry,5 and 10 mL water swallows ×3. Pharyngeal peristaltic pressures were recorded using a high resolution (HR) manometric system and a catheter assembly with 36 circumferential sensors spaced at 1 cm intervals positioned trans-nasally to traverse the pharynx, UES and proximal esophagus.

KEY RESULTS

Both site-specific pressure data and the Pharyngeal contractile integral (PhCI) showed wide dispersion ranging between values under 50 mm Hg to over 300 mm Hg and 100-600 mm Hg/cm/s,respectively. There was also wide range of dispersion of data for both the standard deviations and the coefficient of variation for all sites (P=.001). The coefficient of variation for PhCI ranged between 0.02 and 0.25 representing data dispersion of 2-25 percent of the mean among subjects (P=.001). Position, age and volume of swallowed fluid did not influence the magnitude of variability.

CONCLUSIONS

Deglutitive Pharyngeal peristalsis generates pressures with significant degree of site-related and inter-subject variability. This variability is not influenced by age, position and volume of swallowed fluid.

Pharyngeal peristaltic pressure variability, operational range, and functional reserve

The present understanding of pharyngeal motor function remains incomplete. Among the remaining gaps of knowledge in this regard is the magnitude of variability of pharyngeal peristaltic pressure amplitude. Although variability can pose difficulty in interpretation of manometric findings, its magnitude can inform the operational range and reserve of the pharyngeal contractile function. We aimed to define the intra- and intersubject and intersession variability of select pharyngeal manometric parameters and, using this information, determine the number of swallow repetitions for acquiring reliable pharyngeal manometric data. We recorded pharyngeal peristalsis in 10 healthy subjects (age: 50 ± 25 yr, 5 women) by high-resolution manometry during two separate sessions of 20 sequences of 0.5-ml water swallows. Two-way ANOVA showed significant variation in the mean peak peristaltic pressure value across sites (P < 0.0001) as well as within the data at each site (P < 0.0001). Similarly, the pharyngeal contractile integral exhibited significant inter- (P = 0.003) and intrasubject (P < 0.001) variability. The Shapiro-Wilk normality test showed mixed results, in that some sites showed normally distributed data, whereas others did not. A robust Monte Carlo simulation showed that the nominal sample size was different for various tested metrics. For a power of 0.8, commonly accepted as an adequate threshold for acceptable statistical power, the optimal sample size for various peristaltic parameters ranged between 3 and 15. There is significant intra- and intersubject variability in site-specific and integrated parameters of pharyngeal peristalsis. The observed variance indicates a significant operational range and reserve in pharyngeal contractile function while necessitating parameter-specific sample size for reliable results.NEW & NOTEWORTHY Intra- and intersubject variability are significant and different at various sites within the contractile pharynx. In addition, significant swallow-to-swallow and subject-to-subject variability exists in pharyngeal contractile integral. The range of intrasubject variability indicates the existence of broad operational range and reserve. Lastly, our variability studies informed Monte Carlo and power analyses, yielding estimates of sample size that would ensure accurate representation of pressure metric variability.

Effects of laryngeal restriction on pharyngeal peristalsis and biomechanics: Clinical implications

To date, rehabilitative exercises aimed at strengthening the pharyngeal muscles have not been developed due to the inability to successfully overload and fatigue these muscles during their contraction, a necessary requirement for strength training. The purpose of this study was to test the hypothesis that applying resistance against anterosuperior movement of the hyolaryngeal complex will overload the pharyngeal muscles and by repetitive swallowing will result in their fatigue manifested by a reduction in pharyngeal peristaltic amplitude. Studies were done in two groups. In group 1 studies 15 healthy subjects (age: 42 ± 14 yr, 11 females) were studied to determine whether imposing resistance to swallowing using a handmade device can affect the swallow-induced hyolaryngeal excursion and related upper esophageal sphincter (UES) opening. In group 2, an additional 15 healthy subjects (age 56 ± 25 yr, 7 females) were studied to determine whether imposing resistance to the anterosuperior excursion of the hyolaryngeal complex induces fatigue manifested as reduction in pharyngeal contractile pressure during repeated swallowing. Analysis of the video recordings showed significant decrease in maximum deglutitive superior laryngeal excursion and UES opening diameter (P < 0.01) due to resistive load. Consecutive swallows against the resistive load showed significant decrease in pharyngeal contractile integral (PhCI) values (P < 0.01). Correlation analysis showed a significant negative correlation between PhCI and successive swallows, suggesting "fatigue" (P < 0.001). In conclusion, repeated swallows against a resistive load induced by restricting the anterosuperior excursion of the larynx safely induces fatigue in pharyngeal peristalsis and thus has the potential to strengthen the pharyngeal contractile function.

Cigarette smoking is a modifiable risk factor for Barrett's oesophagus

BACKGROUND

Cigarette smoking has been associated with an increased risk of oesophageal adenocarcinoma (OAC). However, the impact of smoking and more importantly smoking cessation on Barrett's oesophagus (BO) is unclear.

OBJECTIVE

The aim of the study is to evaluate the association between cigarette smoking and presence of BO in a large prospective cohort of patients with gastro-oesophageal reflux disease (GORD).

METHODS

Patients presenting to the endoscopy unit for upper endoscopy completed a validated GORD questionnaire and information on demographics (age, gender, and ethnicity), cigarette smoking [status (current/past), amount (pack years) and duration of smoking cessation], clinical data [medication history, body mass index (BMI), and family history] and endoscopic findings [BO and hiatal hernia] were recorded. Cigarette smokers (current and past) and nonsmokers were compared using Fisher's Exact test for categorical variables and Mann-Whitney test for continuous variables. Effects of cigarette smoking and smoking cessation on BO risk was assessed by stepwise logistic regression analysis.

RESULTS

A total of 1056 patients were included in the analysis [mean age: 57.2 ± 12.7years, Caucasian 880 (83.3%), male 985 (93.3%), and mean BMI 29.6 (SD: ± 5.6)]. 827 (78.3%) were smokers and 229 (21.6%) were nonsmokers. 474 subjects (44.9%) had a previous history of smoking. Anytime smokers were more likely to have BO (adjusted OR: 3.3; 95 CI: 1.7-6.3; p < 0.01). Higher smoking burden (pack years) was associated with higher risk of BO in this GORD cohort (p for trend < 0.01). Duration of smoking cessation was inversely associated with risk of BO (p for trend: 0.01).

CONCLUSION

This study shows that smokers with reflux symptoms have about threefold higher risk of BO compared with nonsmokers, whereas discontinuing smoking is associated with a significant reduced risk. Smoking cessation appears to be a viable option to reduce BO risk in patients with reflux disease.

Functional paraganglioma

Paraganglioma are tumours arising from neural crest cells of the sympathetic and parasympathetic paraganglia. Functional paraganglioma presents with symptoms of catecholamine excess that includes hypertension, flushing, diaphoresis, etc. Non-functional paraganglioma are usually found incidentally during imaging studies. Early diagnoses of functional paraganglioma are important because their removal is often curative. We present the case of a young man who presented with hypertensive crisis and severe headache, who was later found to have functional paraganglioma.

Association of corrected QT interval with long-term mortality in patients with syncope

INTRODUCTION

The electrocardiographic parameters QRS duration, QRS-T angle and QTc can predict mortality in patients with cardiovascular disease. The prgnostic value of these parameters in hospitalized patients with syncope needs investigation.

MATERIAL AND METHODS

We retrospectively studied 590 consecutive patients hospitalized with syncope. After excluding patients with baseline abnormal rhythm, QT- prolonging medications, and missing data, 459 patients were analyzed. Baseline demographic characteristics, co-morbidities, medication use, San Francisco Syncope Rule (SFSR) and Osservatorio Epidemiologico sulla Sincope nel Lazio (OESIL) score and data on mortality were collected. The categorical variables and continuous variables of the 2 groups of patients with prolonged QTc and normal QTc interval were analyzed by Fischer's exact test and Mann-Whitney Test. A stepwise Cox regression model was used for time to death analysis.

RESULTS

Of 459 patients, prolonged QTc interval was observed in 122 (27%). Mean follow-up was 41 months. Patients with prolonged QTc interval had higher prevalence of cardiovascular disease, OESIL score, high risk SFSR, hypertension, dyslipidemia, coronary artery disease, congestive heart failure, and increased mortality. Stepwise Cox regression analysis showed that significant independent prognostic factors for time to death were prolonged QTc interval (p = 0.005), age (p = 0.001), diabetes mellitus (p = 0.001) and history of malignancy (p = 0.006). QRS duration and QRS-T angle were not independent predictors of mortality.

CONCLUSIONS

A prolonged QTc interval is an independent predictor of long-term mortality in hospitalized patients with syncope.

Detection and neutralization of cobra venom using rabbit antiserum in experimental envenomated mice

A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to detect the venom of Indian cobra ( Naja naja naja) in various tissues (brain, heart, lungs, liver, spleen, blood, kidneys, and tissue at the site of injection) of mice after cobra venom injected at different time intervals (0, 2, 4, 6, 8, and 12 h intervals up to 24 h). Whole venom antiserum or individual venom protein antiserum (14, 29, 65, 72, and 99 kDa) could recognize N. n. naja venom by Western blotting and ELISA, and antibody titer was also assayed by ELISA. Antiserum raised against cobra venom in rabbit significantly neutralized the toxicity of venom-injected mice at different time intervals after treatment. The assay could detect N. n. naja venom levels up to 2.5 ng/ml of tissue homogenate, and the venom was detected up to 24 h after venom injection. Venom was detected in brain, heart, lungs, liver, spleen, kidneys, tissue at the bite area, and blood. As observed in mice, tissue at the site of bite area showed the highest concentration of venom and the brain showed the least. Moderate amounts of venoms were found in liver, spleen, kidneys, heart, and lungs. Development of a simple, rapid, and species-specific diagnostic kit based on this ELISA technique useful to clinicians is discussed.

Practice patterns among U.S. gastroenterologists regarding endoscopic management of Barrett's esophagus

BACKGROUND

Endoscopic management of Barrett's esophagus (BE) has evolved over the past decade; however, the practice patterns for managing BE among gastroenterologists remain unclear.

OBJECTIVE

To assess practice patterns for management of BE among gastroenterologists working in various practice settings.

DESIGN

A random questionnaire-based survey of practicing gastroenterologists in the United States. The questionnaire contained a total of 10 questions pertaining to practice setting, physician demographics, and strategies used for managing BE.

SETTING

Survey of gastroenterologists working in various practice settings.

INTERVENTION

Questionnaire.

MAIN OUTCOME MEASUREMENTS

Practice patterns for endoscopic imaging and management of BE.

RESULTS

The response rate was 45% (236/530). The majority (85%) were gastroenterologists in community practice, 72% were aged 41 to 60 years, 80% had >10 years of experience, and 81% had attended postgraduate courses and/or seminars on BE management. A total of 78% did not use the Prague C & M classification, and about a third used advanced endoscopic imaging routinely (37%) or in selected cases (31%). For nondysplastic BE, 86% practiced surveillance, 12% performed ablation, and 3% did no intervention. For BE with low-grade dysplasia, 56% practiced surveillance, 26% performed endoscopic ablation in all low-grade dysplasia cases, and 18% performed endoscopic ablation in only selected patients with low-grade dysplasia. The majority of respondents (58%) referred their patients with high-grade dysplasia to centers with BE expertise, 13% performed endoscopic ablation in all patients with high-grade dysplasia, 25% performed endoscopic ablation in selected cases only, and 3% referred these patients for surgery. The most frequently used endoscopic eradication therapy was radiofrequency ablation (39%) followed by EMR (17%).

LIMITATIONS

The sample may be unrepresentative, participation in the study was voluntary, and responses may be skewed toward following the guidelines.

CONCLUSION

Results from this survey show that the majority of practicing gastroenterologists in the United States practice surveillance endoscopy in patients with nondysplastic BE and provide endoscopic therapy for those with high-grade dysplasia. The Prague C & M classification and advanced imaging techniques are used by less than a third of gastroenterologists. Practice patterns did not appear to be affected by respondent age or duration of clinical practice.

Persistence of nondysplastic Barrett's esophagus identifies patients at lower risk for esophageal adenocarcinoma: results from a large multicenter cohort

BACKGROUND & AIMS

Recent population-based studies have shown a low risk of esophageal adenocarcinoma (EAC) in patients with nondysplastic Barrett's esophagus (NDBE). We evaluated whether persistence of NDBE over multiple consecutive surveillance endoscopic examinations could be used in risk stratification of patients with Barrett's esophagus (BE).

METHODS

We performed a multicenter outcomes study of a large cohort of patients with BE. Based on the number of consecutive surveillance endoscopies showing NDBE, we identified 5 groups of patients. Patients in group 1 were found to have NDBE at their first esophagogastroduodenoscopy (EGD). Patients in group 2 were found to have NDBE on their first 2 consecutive EGDs. Similarly, patients in groups 3, 4, and 5 were found to have NDBE on 3, 4, and 5 consecutive surveillance EGDs. A logistic regression model was built to determine whether persistence of NDBE independently protected against development of cancer.

RESULTS

Of a total of 3515 patients with BE, 1401 patients met the inclusion criteria (93.3% white; 87.5% men; median age, 60 ±17 years). The median follow-up period was 5 ± 3.9 years (7846 patient-years). The annual risk of EAC in groups 1 to 5 was 0.32%, 0.27%, 0.16%, 0.2%, and 0.11%, respectively (P for trend = .03). After adjusting for age, sex, and length of BE, persistence of NDBE, based on multiple surveillance endoscopies, was associated with a gradually lower likelihood of progression to EAC.

CONCLUSIONS

Persistence of NDBE over several endoscopic examinations identifies patients who are at low risk for development of EAC. These findings support lengthening surveillance intervals or discontinuing surveillance of patients with persistent NDBE.

Antivenom activity of triterpenoid (C34H68O2) from Leucas aspera Linn. against Naja naja naja venom induced toxicity: antioxidant and histological study in mice

The isolated and identified triterpenoid, 1-hydroxytetratriacontane-4-one (C34H68O2), obtained from the methanolic leaf extract of Leucas aspera Linn. was explored for the first time for antisnake venom activity. The plant (L. aspera Linn.) extract significantly antagonized the spectacled cobra (Naja naja naja) venom induced lethal activity in a mouse model. It was compared with commercial antiserum obtained from King Institute of Preventive Medicine (Chennai, Tamil Nadu, India). N. naja naja venom induced a significant decrease in antioxidant superoxide dismutase, glutathione (GSH) peroxidase, catalase, reduced GSH and glutathione-S-transferase activities and increased lipid peroxidase (LPO) activity in different organs such as heart, liver, kidney and lungs. The histological changes following the antivenom treatment were also evaluated in all these organs. There were significant alterations in the histology. Triterpenoid from methanol extract of L. aspera Linn. at a dose level of 75 mg per mouse significantly attenuated (neutralized) the venom-induced antioxidant status and also the LPO activity in different organs.

Clinical utility and interobserver agreement of autofluorescence imaging and magnification narrow-band imaging for the evaluation of Barrett's esophagus: a prospective tandem study

BACKGROUND

New endoscopic imaging techniques, such as autofluorescence imaging (AFI) and narrow-band imaging (NBI), have been developed to improve the detection of neoplastic lesions in Barrett's esophagus (BE).

OBJECTIVE

To evaluate the clinical utility of AFI and magnification NBI to detect high-grade dysplasia (HGD) and early esophageal adenocarcinoma (EAC) and the interobserver agreement.

DESIGN

Prospective tandem study of eligible patients.

SETTING

Single, academic tertiary care center.

PATIENTS

Forty-two patients with a history of confirmed BE were prospectively enrolled.

INTERVENTIONS

The BE segment was examined under high-definition white-light endoscopy, and the presence of visible lesions was recorded. Subsequently, AFI and magnification NBI were performed in tandem on areas of the BE segment away from visible lesions; images obtained by these 2 systems were graded according to the color of reflected light and surface patterns, respectively. Biopsy specimens were obtained at the end of the procedure.

MAIN OUTCOME MEASUREMENTS

The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of the AFI and NBI patterns for the detection of HGD/EAC and interobserver agreement.

RESULTS

Of the 42 patients enrolled, 14 (33%) had HGD/EAC. On patient-based analysis, AFI alone had a sensitivity, specificity, and NPV of 50%, 61%, and 71%, respectively, and the overall accuracy for the detection of HGD/EAC patients was 57%. By using magnification NBI in tandem fashion, the sensitivity and NPV improved to 71% and 76%, respectively, with a decrease in specificity to 46% and in overall accuracy to 55%. The 2 techniques had moderate interobserver agreement for both the patterns and prediction of histology.

LIMITATIONS

Uncontrolled study performed at an academic center by expert endoscopists in a high-risk population.

CONCLUSIONS

By using a multimodality endoscope, both AFI and magnification NBI had limited clinical accuracy and moderate overall interobserver agreement. AFI does not appear to be useful as a broad-based technique for the detection of neoplasia in patients with BE.

Demystifying seronegative autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) has been classified into type 1 and type 2 subtypes. Serum immunoglobulin G4 (IgG4) elevation characterizes type 1 AIP. Type 2 AIP and a subset of type 1 AIP are seronegative, i.e., have normal serum IgG4 levels.

AIM

We compared the profiles of the three subsets of AIP to identify the unique characteristics of seronegative type 1 AIP and type 2 AIP.

METHODS

We compared the clinical profiles of 69 seropositive type 1 AIP patients, 21 seronegative type 1 AIP patients and 22 type 2 AIP patients.

RESULTS

Among type 1 AIP, seronegative group had similar clinical profiles when compared to seropositive group except that they were more likely to undergo surgical resection than seropositive patients (p = 0.001). Seronegative type I AIP patients were older (61.9 ± 13.7 vs 45.3 ± 17.4; p = 0.004), and differed in the occurrence of other organ involvement (OOI) (71.4% vs 0%; p < 0.001) and disease relapse (33.3% vs 0%; p = 0.005) when compared with type 2 AIP. All seronegative type 1 AIP patients had at least one of the following -OOI, disease relapse, and age >50 years while none of the type 2 AIP had OOI or disease relapse.

CONCLUSIONS

Seronegative and seropositive type 1 AIP patients have similar clinical profiles, which are distinct from that of type 2 AIP. Among the seronegative AIP group, patients are more likely to have type 1 AIP rather than type 2 AIP if they are older than 50 years or have OOI or disease relapse.

High sensitivity magnetic imaging using an array of spins in diamond

We present a solid state magnetic field imaging technique using a two-dimensional array of spins in diamond. The magnetic sensing spin array is made of nitrogen vacancy (NV) centers created at shallow depths. Their optical response is used for measuring external magnetic fields in close proximity. Optically detected magnetic resonance is read out from a 60 x 60 microm(2) field of view in a multiplexed manner using a charge coupled device camera. We experimentally demonstrate full two-dimensional vector imaging of the magnetic field produced by a pair of current carrying microwires. The presented wide-field NV magnetometer offers, in addition to its high magnetic sensitivity and vector reconstruction, an unprecedented spatiotemporal resolution and functionality at room temperature.

Dynamic polarization of single nuclear spins by optical pumping of nitrogen-vacancy color centers in diamond at room temperature

We report a versatile method to polarize single nuclear spins in diamond, based on optical pumping of a single nitrogen-vacancy (NV) defect and mediated by a level anticrossing in its excited state. A nuclear-spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated with the NV center, corresponding to microK effective nuclear-spin temperature. We then show simultaneous initialization of two nuclear spins in the vicinity of a NV defect. Such robust control of nuclear-spin states is a key ingredient for further scaling up of nuclear-spin based quantum registers in diamond.

Studies on the immunomodulatory effect of extract of Cyanodon dactylon in shrimp, Penaeus monodon, and its efficacy to protect the shrimp from white spot syndrome virus (WSSV)

The present study investigates the protection of shrimp Penaeus monodon against white spot syndrome virus (WSSV) using antiviral plant extract derived from Cyanodon dactylon and the modulation of the shrimp non-specific immunity. To determine the antiviral activity, the shrimp were treated by both in vitro (intramuscular injection) and in vivo (orally with feed) methods at the concentration of 2mg per animal and 2% of the plant extract incorporated with commercially available artificial pellet feed, respectively. The antiviral activity of C. dactylon plant extract was confirmed by PCR, bioassay and Western blot analysis. In the present study, anti-WSSV activity of C. dactylon plant extract by in vivo and in vitro methods showed strong antiviral activity and the immunological parameters such as proPO, O(2)(-), NO, THC and clotting time were all significantly (P<0.05) higher in the WSSV-infected shrimp treated with plant extract when compared to control groups. These results strongly indicate that in vivo and in vitro administration of C. dactylon plant extract enhances immunity of the shrimp. Based on the present data and the advantages of plant extract available at low price, we believe that oral administration of C. dactylon plant extract along with the pellet feed is a potential prophylactic agent against WSSV infection of shrimp.

Temporal coherence of photons emitted by single nitrogen-vacancy defect centers in diamond using optical Rabi-oscillations

Photon interference among distant quantum emitters is a promising method to generate large scale quantum networks. Interference is best achieved when photons show long coherence times. For the nitrogen-vacancy defect center in diamond we measure the coherence times of photons via optically induced Rabi oscillations. Experiments reveal a close to Fourier-transform (i.e., lifetime) limited width of photons emitted even when averaged over minutes. The projected contrast of two-photon interference (0.8) is high enough to envisage applications in quantum information processing. We report 12 and 7.8 ns excited state lifetimes depending on the spin state of the defect.

Experimental transmission and tissue tropism of white spot syndrome virus (WSSV) in two species of lobsters, Panulirus homarus and Panulirus ornatus

The susceptibility of two species of lobsters, Panulirus homarus and Panulirus ornatus to white spot syndrome virus (WSSV) was tested by oral route and intramuscular injection. The results revealed that these lobsters were as highly susceptible as marine shrimp when the WSSV was administered intramuscularly. The WSSV caused 100% mortality in both Panulirus homarus and Panulirus ornatus, at 168 and 120 h, respectively, after intramuscular injection and failed to cause mortality when given orally. The presence of WSSV in moribund lobsters was confirmed by single-step and nested PCR, Western blot, histology, and bioassay test. It was found in eyestalk, gill, head muscle, tail muscle, hemolymph, appendages, and stomach. In lobsters with oral route infection, all tested organs except stomach and head muscle was negative for WSSV by nested PCR at 120 h post-inoculation. The stomach and head muscle was positive by nested PCR at 120 h p.i., but negative at 168 h p.i. Western blot analysis was negative in all the tested organs of both species of lobster at 120 h post-inoculation by oral route.

Tumorigenicity assessments of Per.C6 cells and of an Ad5-vectored HIV-1 vaccine produced on this continuous cell line

PER.C6, a cell line derived from human embryonic retinal cells transformed with the Adenovirus Type 5 (Ad5) E1A and E1B genes, is used to produce E1-deleted Ad5 vectors such as the MRKAd5 HIV-1 gag vaccine. While whole, live PER.C6 cells are capable of growing as tumours when transplanted subcutaneously into immunodeficient nude mice at a high dosage, the process for vaccine production includes filtration steps and other methods which effectively preclude contamination by intact viable substrate cells. However, because of the neoplastic nature of this cell line, we carried out a series of investigations to assess the tumorigenic risk posed by residuals from the cell substrate in a vaccine. To address concerns about transmission of oncogenic DNA, we demonstrated that purified PER.C6 cellular DNA does not induce tumours in newborn hamsters or nude mice. To address concerns about other potential residuals, including hypothetical adventitious tumour viruses, we demonstrated that a PER.C6 cell lysate and a MRKAd5 HIV-1 gag vaccine produced on PER.C6 cells do not induce tumours in newborn hamsters or newborn rats. These results, in conjunction with the wide panel of viral safety tests performed on these cells, support the safety of the PER.C6 as a cell substrate for vaccine production.

A self-learning coupled map lattice for vortex shedding in cable and cylinder wakes

A coupled map lattice (CML) with self-learning features is developed to model flow over freely vibrating cables and stationary cylinders at low Reynolds numbers. Coupled map lattices that combine a series of low-dimensional circle maps with a diffusion model have been used previously to predict qualitative features of these flows. However, the simple nature of these CML models implies that there will be unmodeled wake features if a detailed, quantitative comparison is made with laboratory or simulated wake flows. Motivated by a desire to develop an improved CML model, we incorporate self-learning features into a new CML that is first trained to precisely estimate wake patterns from a target numerical simulation. A new convective-diffusive map that includes additional wake dynamics is developed. The new self-learning CML uses an adaptive estimation scheme (multivariable least-squares algorithm). Studies of this approach are conducted using wake patterns from a Navier-Stokes solution (spectral element-based NEKTAR simulation) of freely vibrating cable wakes at Reynolds numbers Re=100. It is shown that the self-learning model accurately and efficiently estimates the simulated wake patterns. The self-learning scheme is then successfully applied to vortex shedding patterns obtained from experiments on stationary cylinders. This constitutes a first step toward the use of the self-learning CML as a wake model in flow control studies of laboratory wake flows.

Experimental infection of twenty species of Indian marine crabs with white spot syndrome virus (WSSV)

Twenty species of Indian marine crabs were experimentally infected with white spot syndrome virus (WSSV), via the oral route and intramuscular injection, to determine their viral susceptibility. We determined that 16 species (Calappa philargius, Charybdis annulata, C. lucifera, Doclea hybrida, Grapsus albolineatus, Halimede ochtodes, Liagore rubronaculata, Lithodes maja, Matuta miersi, Paradorippe granulata, Parthenope prensor, Philyra syndactyla, Podophthalmus vigil, Portunus sanquinolentus, Scylla serrata and Thalamita danae) were susceptible and 4 (Atergatis integerrimus, Charybdis natator, Demania splendida or Menippe rumphii) were refractive at 50 d post-infection (p.i.). The presence of WSSV in these crabs was confirmed by PCR tests, histology and bioassay. WSSV was found in the gill, heart, eyestalks, striated muscle and cephalothoraxic tissue. The 4 WSSV-refractive species represent potential reservoirs or carriers of WSSV.

Ca(2+)-calmodulin antagonist chlorpromazine and poly(ADP-ribose) polymerase modulators 4-aminobenzamide and nicotinamide influence hepatic expression of BCL-XL and P53 and protect against acetaminophen-induced programmed and unprogrammed cell death in mice

Acetaminophen (AAP), the analgesic hepatotoxicant, is a powerful inducer of oxidative stress, DNA fragmentation, and apoptosis. The anti-apoptotic oncogene bcl-XL, and the pro-apoptotic oncogene p53 are two key regulators of cell cycle progression and/or apoptosis subsequent to DNA damage in vitro and in vivo. This study investigated the effect of AAP on the expression of these oncogenes and whether agents that modulate DNA fragmentation (chlorpromazine, CPZ) and DNA repair through poly(ADP-Ribose) polymerase (PARP) activity (4-AB: 4-aminobenzamide) can protect against AAP-induced hepatotoxicity by inhibiting oxidative stress, DNA fragmentation, and/or by altering the expression of bcl-XL and p53. In addition, the protective effect of supplemental nicotinamide (NICO), known to be depleted in cells with high PARP activity during DNA repair, is similarly evaluated. Male ICR mice (3 months old) were administered vehicle alone; nontoxic doses of 4-AB (400 mg/kg, ip), NICO (250 mg/kg, ip) or CPZ (25 mg/kg, ip), hepatotoxic dose of AAP alone (500 mg/kg, ip), or AAP plus one of the protective agents 1 h later. All animals were sacrificed 24 h following AAP administration. Serum alanine aminotransferase activity (ALT), hepatic histopathology and lipid peroxidation, DNA damage, and expression of bcl-XL and p53 (western blot analysis) were compared in various groups. All of the three agents significantly prevented AAP-induced liver injury, lipid peroxidation, DNA damage, and associated apoptotic and necrotic cell deaths, 4-AB being the most effective and NICO the least. Compared to control, there was a considerable decrease in bcl-XL expression, and an increase in p53 expression in AAP-exposed livers. The effect of AAP on bcl-XL was antagonized and that on p53 was synergized by the PARP-modulator 4-AB as well as NICO, whereas the endonuclease inhibitor CPZ was without effect on either bcl-XL or p53 expression. These results suggest that the hepatotoxic effect of AAP involves multiple mechanisms including oxidative stress, upregulation of endonuclease (or caspase-activated DNAse) and alteration of pro- and anti-apoptotic oncogenes. The observed antagonism of AAP-induced hepatocellular apoptosis and/or necrosis by modulators of multiple processes including DNA repair suggests the likelihood that a more effective therapy against AAP intoxication should involve a combination of antidotes.

Secalonic acid D alters the nature of and inhibits the binding of the transcription factors to the phorbol 12-O-tetradecanoate-13 acetate-response element in the developing murine secondary palate

Secalonic acid D (SAD), a mycotoxin produced by Penicillium oxalicum in corn, induces cleft palate (CP) in the offspring of exposed dams. Results of recent studies suggest that protein kinase C (PKC) inhibition by SAD may be relevant to its CP-induction. Downstream effects of PKC are determined by the nature of transcription factors (TF) that form the activator protein-1 (AP-1) and the binding of AP-1 (and other TF) to the phorbol 12-O-tetradecanoate-13 acetate-response element (TRE) to form AP-1-TRE complex, neither of which have been studied in the palate. The aims of the present study were to identify the components of the murine palatal AP-1-TRE complex during development and to uncover the effects of SAD on this complex. Western blots and gel mobility shift assays of control palatal nuclear extracts revealed that, although all relevant TF are present in the palate throughout development, only cyclic-AMP response element (CRE) binding protein (CREB) and CRE-modulator protein-1 (CREM-1) and activating transcription factor-1 bound to TRE on Gestation Day (GD) 12. The pattern shifted to c-Jun and c-Fos (known AP-1 components) on GD 13 and 14. In SAD-treated offspring, however, CREM-1 alone; c-Jun, c-Fos, and CREB; and c-Jun and c-Fos bound to TRE on GD 12, 13, and 14, respectively. Binding of TF to TRE was inhibited by SAD on both GD 12 and 13. These results suggest that a dynamic shift in the binding of TF to TRE from PKA- to PKC-responsive TF occurs during palate development and that teratogens such as SAD can alter both the nature and extent of TF binding to TRE.

Novel mechanism of protein kinase C inhibition involving the pseudosubstrate region by secalonic acid D in vitro

Evidence from studies in mice suggests a mechanistic role for the inhibition of conventional isoforms of protein kinase C (cPKC) in the development of cleft palate (CP) in the offspring of female mice treated with the mycotoxin, secalonic acid D (SAD). These experiments were aimed at assessing whether SAD inhibits commercially available pure cPKC (PKCalpha, -beta, -gamma) and at identifying the mechanism of such an inhibition in vitro. Secalonic acid D inhibited the three isozymes similarly (IC50 of 5 to 6.2 microM by direct extrapolation and 2.7 to 4 microM by logarithmic regression). The loss of inhibitory effect of SAD upon removal of the regulatory domain of PKCbetaII, the most predominant cPKC in the palate, suggested that the inhibition was mediated by the regulatory subunit. Kinetic analysis suggested a lack of competitive interaction for SAD with the binding sites for Ca(2+) and phosphatidyl serine (PS). Antibody directed against residues 19-32 of the pseudosubstrate region of PKCbetaII, however, competitively reversed the inhibition of PKCbetaII by SAD, suggesting that the pseudosubstrate is the site of interaction of SAD. Further, SAD inhibited the cleavage of the pseudosubstrate from PKCbetaII by the endoproteinase Arg-C. The fact that the activity of Arg-C itself was not inhibited by SAD suggests that SAD interferes with the preceding step involving the cofactor-induced release of the pseudosubstrate from the active site of PKCbetaII, a novel mechanism.

Expression and activity of protein kinase C isoenzymes during normal and abnormal murine palate development

Protein kinase C (PKC) plays a critical role in signal transduction, mediating various cellular events critical for normal development, including that of the palate. In vivo and in vitro studies suggest the relevance of the inhibition of PKC by the mycotoxin, secalonic acid D (SAD), to its induction of cleft palate (CP) in mice. In the present study, temporal and spatial expression and the activity of various PKC isoenzymes were studied in the control and SAD-exposed murine embryonic palate during gestational days (GD) 12-14.5 by western blotting, immunohistochemistry, and phosphotransfer assay. The Ca2+-dependent isoenzymes, PKC alpha and PKC betaII, showed significant expression on GD 12.0, which gradually decreased through GD 14.5, whereas PKC betaI and PKC gamma were negligible throughout. All Ca2+-independent isoenzymes (epsilon, delta, and zeta) were expressed more abundantly and, in contrast to the Ca2+-dependent ones, progressively increased with age. SAD failed to alter this pattern of expression but enhanced the phosphorylation of PKC epsilon throughout development. Immunohistochemical analysis revealed an isoenzyme-specific distribution of PKC between the epithelium and mesenchyme. As expected, SAD significantly inhibited the total Ca2+-dependent PKC activity in palatal extracts. Although total Ca2+-independent PKC activity in palatal extracts was unaffected by SAD, individual pure isoenzymes were either selectively inhibited (PKC zeta), stimulated (PKC delta), or unaffected (PKC epsilon) by SAD. These results show that PKC isoenzymes exhibit dynamic temporal and spatial patterns of expression and activity in the developing palate and that the induction of CP by SAD is associated with an alteration in their activation and/or activity.