A pragmatic clinical trial assessing the effect of a targeted notification and clinical support pathway on the diagnostic evaluation and treatment of individuals with left ventricular hypertrophy (NOTIFY-LVH)

BACKGROUND

Electronic health records contain vast amounts of cardiovascular data, including potential clues suggesting unrecognized conditions. One important example is the identification of left ventricular hypertrophy (LVH) on echocardiography. If the underlying causes are untreated, individuals are at increased risk of developing clinically significant pathology. As the most common cause of LVH, hypertension accounts for more cardiovascular deaths than any other modifiable risk factor. Contemporary healthcare systems have suboptimal mechanisms for detecting and effectively implementing hypertension treatment before downstream consequences develop. Thus, there is an urgent need to validate alternative intervention strategies for individuals with preexisting-but potentially unrecognized-LVH.

METHODS

Through a randomized pragmatic trial within a large integrated healthcare system, we will study the impact of a centralized clinical support pathway on the diagnosis and treatment of hypertension and other LVH-associated diseases in individuals with echocardiographic evidence of concentric LVH. Approximately 600 individuals who are not treated for hypertension and who do not have a known cardiomyopathy will be randomized. The intervention will be directed by population health coordinators who will notify longitudinal clinicians and offer to assist with the diagnostic evaluation of LVH. Our hypothesis is that an intervention that alerts clinicians to the presence of LVH will increase the detection and treatment of hypertension and the diagnosis of alternative causes of thickened myocardium. The primary outcome is the initiation of an antihypertensive medication. Secondary outcomes include new hypertension diagnoses and new cardiomyopathy diagnoses. The trial began in March 2023 and outcomes will be assessed 12 months from the start of follow-up.

CONCLUSION

The NOTIFY-LVH trial will assess the efficacy of a centralized intervention to improve the detection and treatment of hypertension and LVH-associated diseases. Additionally, it will serve as a proof-of-concept for how to effectively utilize previously collected electronic health data to improve the recognition and management of a broad range of chronic cardiovascular conditions.

TRIAL REGISTRATION

NCT05713916.

Improving guideline-based anticoagulation in atrial fibrillation: A systematic literature review of prospective trials

BACKGROUND

Guidelines for anticoagulation in patients with atrial fibrillation (AF) aim to decrease the risk of ischemic stroke. However, there is a gap in actual practice between patients who have an indication for anticoagulation and those who are actually prescribed anticoagulation.

OBJECTIVE

We sought to evaluate the efficacy of prior population-based interventions aimed at decreasing this AF anticoagulation gap.

METHODS

This study was prospectively registered in the International Prospective Register of Systematic Reviews database (CRD42021287875). A systematic literature review was conducted to obtain all prospective individually randomized and cluster randomized trials by searching 4 electronic databases: PubMed, Google Scholar, Web of Science, and Medline.

RESULTS

After a review of 1474 studies, 20 trials were included in this systematic literature review. Forty-five percent were effective in decreasing the AF anticoagulation gap. Trial interventions that improved anticoagulation prescribing included 6 trials of electronic risk assessment or decision support, 1 trial of provider education, 2 trials of new protocol or pathway, and 2 trials of patient education. Six of 15 ambulatory trials, 2 of 4 inpatient trials, and 1 trial that spanned inpatient and outpatient settings improved anticoagulation prescribing rates. Interventions focused on patient education, provider education, and electronic risk assessment or decision support increased absolute appropriate anticoagulation prescribing by 8.3%, 4.9%, and 2.0%, respectively.

CONCLUSION

Interventions aimed at improving anticoagulation prescribing patterns in AF can be effective, although there is heterogeneity in outcomes across intervention type. The most effective interventions appeared to target patient education, provider education, and electronic risk assessment or decision support.

764 ROCKWOOD CLINICAL FRAILTY SCALE TO PREDICT LENGTH OF STAY,INPATIENT MORTALITY & READMISSION RATE IN A COMMUNITY HOSPITAL SETTING

Introduction

Frailty is prevalent in elderly patients in acute medical wards. It is recognised that length of stay (LOS), inpatient mortality and readmission rates rise with increasing frailty. (Reference: Specialised Clinical Frailty Network: Clinical frailty Scale. 2018. https://www.scfn.org.uk/clinical-frailty-scale) The Rockwood clinical frailty scale (CFS) is a well-recognised and validated tool, which can be easily incorporated into the comprehensive geriatric assessment to identify the frailest patients and aid in clinical decision making. We collected data on elderly patients in a non-acute community setting to assess the relationship between degree of frailty and outcomes, in this subset of inpatients.

Methods

Data was collected on 200 patients admitted to a geriatrician led community hospital over an 8 month period. Patients were all transferred from the affiliated acute hospital site (both medical and surgical wards).Commonest acute diagnoses were: falls, fractures, infections, delirium and heart failure. Premorbid CFS was recorded and patients were divided into 2 groups: CFS ≤ 4: versus CFS ≥5, and outcomes compared to degree of frailty.

Results

Of 200 patients, aged ≥65 years, admitted from the acute hospital setting to the community hospital,28.5% had premorbid CFS ≤4,and 71.5% had premorbid CFS ≥5. Median LOS in the community hospital was 10 days in the less frail group compared to 13 days in the frailer group. One year emergency readmission rate was 58.5% in those with CFS ≤4,and 67% in those with CFS ≥5.

Conclusion(s)

Accurate recording of premorbid CFS in the non-acute hospital setting can be used to help predict patient outcomes. Used in conjunction with the CGA it is a tool that can aid decision making and prompt discussions with patients and/or families re advance care planning, specifically re suitability of transfer back to the acute hospital setting in the event of a decline in health.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Abstract 240: Assessing the Lack of Appropriate Anticoagulation in Patients With Atrial Fibrillation - Implications for Cardiology Registry-Based Care

Intro: Anticoagulation is indicated for many patients with atrial fibrillation (AF) for prevention of cardioembolic stroke, although national proportions of eligible patients receiving anticoagulation remain suboptimal. Automated and semi-automated quality improvement techniques including registries and population health coordinators may help identify and increase eligible patients to receive anticoagulation.

Methods: We queried our electronic health record to identify patients without anticoagulation but with atrial fibrillation (as identified as either paroxysmal atrial fibrillation, persistent atrial fibrillation, chronic atrial fibrillation, typical atrial flutter, atypical atrial flutter, or unspecified atrial flutter) either on the problem list or as billed administrative claims between September 2016 - September 2019 in MGH outpatient cardiology clinics. All patients were participating in MGH cardiology, with their primary care based either within MGH or outside of MGH. Then, we conducted detailed chart review to calculate thromboembolic risk with respective CHADS-VASC score and confirmed that the patient was not receiving anticoagulation. A typology was developed as charts were reviewed to categorize reasons for lacking anticoagulation. These categories were grouped into broader categories representing a (1) potential quality problem or (2) appropriate lack of anticoagulation.

Results: Of 100 patients, 59 were deemed to have a potential quality problem and 41 were deemed to have appropriate lack of anticoagulation. Of the patients with a potential quality problem, 11 have a CHADS VASC score of 1, 18 have a CHADS VASC score of 2, 6 have a CHADS VASC score of 3, 10 have a CHADS VASC score of 4, and 8 have a CHADS of 5, and 6 have a CHADS VASC of 6 or above. Additionally, 3 patients have been lost to follow up, 12 patients had presented with current symptoms of AF within the last year, and 44 patients exhibited acute history of AF symptoms. 41 patients did not present concern for multiple reasons including: CHADS VASC=0, deceased, patients declined medication, followed by outside cardiologist, technology and medication discrepancies, inaccurate administrative data for AF, and prior major bleeding.

Conclusions: We found that most un-anticoagulated AF patients identified by administrative claims and EHR problem lists are likely eligible for anticoagulation. Of those, most have a history of paroxysmal AF. As such, registry-based strategies based on queries of past AF may improve rates of anticoagulation in this population. Since automated queries still detect many patients with contraindications such as bleeding or inaccurate administrative data, manual review of administrative queries is likely to be important in quality efforts for AF.

Two-layered susceptibility vessel sign is associated with biochemically quantified thrombus red blood cell content

BACKGROUND AND PURPOSE

Better characterization of the thrombus could be useful to determine acute ischaemic stroke (AIS) aetiology and predict response to thrombolysis and endovascular therapy (EVT). To test the hypothesis that susceptibility vessel sign (SVS) on baseline magnetic resonance imaging (MRI) is related to red blood cell (RBC) content of AIS thrombi, the total haemoglobin contents (HbCs) of AIS thrombi retrieved by EVT from patients with or without SVS or two-layered SVS (TLSVS) were compared.

METHODS

Baseline MRI of 84 anterior AIS patients was reviewed by neuro-radiologists blinded to clinical and biochemical data. Thrombi from these patients were retrieved by EVT and analysed for HbC by quantitative enzyme-linked immunosorbent assay and measurement of haem concentration.

RESULTS

Susceptibility vessel sign and TLSVS were respectively observed in 85.7% and 50.0% of cases. The median HbC content was 253 µg/mg thrombus (interquartile range 177-333) and the median haem content was 219 µg/mg thrombus (131-264). Thrombus HbC and haem content were highly correlated with thrombus RBC content determined by flow cytometry (r = 0.94). Thrombi from patients with TLSVS weighed more [31.1 (16.5-68.3) mg vs. 17.7 (11.7-33.3) mg; P = 0.005] and had a higher HbC content [278 (221-331) µg/mg vs. 196 (139-301) µg/mg; P = 0.010] compared to thrombi from patients without TLSVS. There was no difference in thrombus weight or HbC content according to SVS status.

CONCLUSIONS

Our study shows that TLSVS is significantly associated with a higher thrombus weight and RBC content, as determined by quantitative assays.

Health economic analysis of a cluster-randomised trial (OptiBIRTH) designed to increase rates of vaginal birth after caesarean section

OBJECTIVE

To perform a health economic analysis of an intervention designed to increase rates of vaginal birth after caesarean, compared with usual care.

DESIGN

Economic analysis alongside the cluster-randomised OptiBIRTH trial (Optimising childbirth by increasing vaginal birth after caesarean section (VBAC) through enhanced women-centred care).

SETTING

Fifteen maternity units in three European countries - Germany (five), Ireland (five), and Italy (five) - with relatively low VBAC rates.

POPULATION

Pregnant women with a history of one previous lower-segment caesarean section; sites were randomised (3:2) to intervention or control.

METHODS

A cost-utility analysis from both societal and health-services perspectives, using a decision tree.

MAIN OUTCOME MEASURES

Costs and resource use per woman and infant were compared between the control and intervention group by country, from pregnancy recognition until 3 months postpartum. Based on the caesarean section rates, and maternal and neonatal morbidities and mortality, the incremental cost-utility ratios were calculated per country.

RESULTS

The mean difference in costs per quality-adjusted life years (QALYs) gained from a societal perspective between the intervention and the control group, using a probabilistic sensitivity analysis, was: €263 (95% CI €258-268) and 0.008 QALYs (95% CI 0.008-0.009 QALYs) for Germany, €456 (95% CI €448-464) and 0.052 QALYs (95% CI 0.051-0.053 QALYs) for Ireland, and €1174 (95% CI €1170-1178) and 0.006 QALYs (95% CI 0.005-0.007 QALYs) for Italy. The incremental cost-utility ratios were €33,741/QALY for Germany, €8785/QALY for Ireland, and €214,318/QALY for Italy, with a 51% probability of being cost-effective for Germany, 92% for Ireland, and 15% for Italy.

CONCLUSION

The OptiBIRTH intervention was likely to be cost-effective in Ireland and Germany.

TWEETABLE ABSTRACT

The OptiBIRTH intervention (to increase VBAC rates) is likely to be cost-effective in Germany and Ireland.

Porphyrin derivatives as potent and selective blockers of neuronal Kv1 channels

Docking model of compound12into the homology model of Kv1.1.

Reliability of Repeated Measurements on Post-Burn Scars with Corneometer CM 825(®)

BACKGROUND/PURPOSE

The water content in burn scars, the parameter of stratum corneum water holding capacity, is an important feature in evaluation of biophysical properties of scars. Nevertheless, quantifiying this parameter is a challenge. In this study, the reliability of repeated water content measurements with Corneometer CM825(®) on (burn) scars was investigated.

METHODS

Intra-observer reliability, inter-observer reliability and day-by-day variability were examined on 30 scars by means of intra-class correlation coefficient (ICC) and within-subject coefficient of variation (WSCV). Bland-Altman plots with '95% limits of agreement' were constructed.

RESULTS

Results revealed excellent ICC values (ICCintra  = 0.985; ICCinter  = 0.984) with relatively low WSCV (WSCVintra  = 6.3%; WSCVinter  = 10.6%) for respectively intra- and inter-observer reliability. However, the Bland-Altman plot showed that more than 5% of differences were expected to exceed 4 a.u., the limit of what has been defined as a clinically acceptable difference. Results for day-by-day variability showed good ICC value (ICCday-by-day  = 0.849) and higher WSCV (WSCVday-by-day  = 20.5%).

CONCLUSION

The Corneometer CM825(®) is an objective and sensitive instrument for water content measurements. On the basis of our results, we concluded that the instrument can be used in clinical trials, but only under very strict conditions with standardized test protocol, preferably in combination with the evaluation of other physiological parameters.

An integrated pressure and pathway approach to the spatial analysis of groundwater nitrate: a case study from the southeast of Ireland

Excess nitrogen in soil, aquatic and atmospheric environments is an escalating global problem. Eutrophication is the principal threat to surface water quality in the Republic of Ireland. European Union Water Framework Directive (2000/60/EC) water quality status assessments found that 16% of Irish groundwater bodies were 'at risk' of poor status due to the potential deterioration of associated estuarine and coastal water quality by nitrate from groundwater. This paper presents a methodology for evaluating pressure and pathway parameters affecting the spatial distribution of groundwater nitrate, investigated at a regional scale using existing national spatial datasets. The potential for nitrate transfer to groundwater was rated based on the introduced concepts of Pressure Loading and Pathway Connectivity Rating, each based on a combination of selected pressure and pathway parameters respectively. In the region studied, the South Eastern River Basin District of Ireland, this methodology identified that pathway parameters were more important than pressure parameters in understanding the spatial distribution of groundwater nitrate. Statistical analyses supported these findings and further demonstrated that the proportion of poorly drained soils, arable land, karstic flow regimes, regionally important bedrock aquifers and high vulnerability groundwater within the zones of contribution of the monitoring points are statistically significantly related to groundwater nitrate concentrations. Soil type was found to be the most important parameter. Analysis of variance showed that a number of the pressure and pathway parameters are interrelated. The parameters identified by the presented methodology may provide useful insights into the best way to manage and mitigate the influence of nitrate contamination of groundwater in this region. It is suggested that the identification of critical source areas based on the identified parameters would be an appropriate management tool, enabling planning and enforcement resources to be focussed on areas which will yield most benefit.

Bladder afferent sensitivity in wild-type and TRPV1 knockout mice

Understanding bladder afferent pathways may reveal novel targets for therapy of lower urinary tract disorders such as overactive bladder syndrome and cystitis. Several potential candidate molecules have been postulated as playing a significant role in bladder function. One such candidate is the transient receptor potential vanilloid 1 (TRPV1) ion channel. Mice lacking the TRPV1 channel have altered micturition thresholds suggesting that TRPV1 channels may play a role in the detection of bladder filling. The aim of this study was therefore to investigate the role of TRPV1 receptors in controlling bladder afferent sensitivity in the mouse using pharmacological receptor blockade and genetic deletion of the channel. Multiunit afferent activity was recorded in vitro from bladder afferents taken from wild-type (TRPV+/+) mice and knockout (TRPV1-/-) mice. In wild-type preparations, ramp distension of the bladder to a maximal pressure of 40 mmHg produced a graded increase in afferent activity. Bath application of the TRPV1 antagonist capsazepine (10 mum) caused a significant attenuation of afferent discharge in TRPV1+/+ mice. Afferent responses to distension were significantly attenuated in TRPV1-/- mice in which sensitivity to intravesical hydrochloric acid (50 mm) and capsaicin (10 microm) were also blunted. Altered mechanosensitivity occurred in the absence of any changes in the pressure-volume relationship during filling indicating that this was not secondary to a change in bladder compliance. Single-unit analysis was used to classify individual afferents into low-threshold and high-threshold fibres. Low threshold afferent responses were attenuated in TRPV1-/- mice compared to the TRPV1+/+ littermates while surprisingly high threshold afferent sensitivity was unchanged. While TRPV1 channels are not considered to be mechanically gated, the present study demonstrates a clear role for TRPV1 in the excitability of particularly low threshold bladder afferents. This suggests that TRPV1 may play an important role in normal bladder function.

Detection and recovery rates achieved using direct plate and enrichment/immunomagnetic separation methods for Escherichia coli O157:H7 in minced beef and on bovine hide

AIMS

To assess the detection and recovery rates achieved with commonly used cultural methods for the enumeration and recovery of Escherichia coli O157:H7 from minced beef and bovine hide.

METHODS AND RESULTS

Minced beef and bovine hide were inoculated with varying concentrations (log(10) 1.58-2.58 CFU g(-1) and log(10) 2.42-4.49 CFU 100 cm(2) respectively) of E. coli O157:H7 and recovered using a direct plate method or an enrichment/immunomagnetic separation (IMS) method and then plated onto SMAC or SMAC-CT in both cases. The direct plate method detected the pathogen consistently from minced beef samples with an average recovery of 69.2-91.2%. From faecal material on the bovine hide the recovery of the pathogen ranged from 1.80 to 64.5% with fresh faeces depending on the inocula while from dried faeces on hide the results ranged from no recovery at all to 25.1%. Enrichment/IMS recovered E. coli O157:H7 at all inocula levels tested in minced beef while the pathogen was only detected consistently at an average inocula level of log(10) 2.73 CFU 100 cm(2) from fresh faeces and log(10) 4.49 CFU 100 cm(2) from dried faeces on bovine hide.

CONCLUSIONS

The direct count enumeration method for E. coli O157:H7 underestimated the numbers of pathogens present. The enrichment/IMS procedure consistently detected the pathogen from minced beef but did not always detect E. coli O157:H7 from faeces on bovine hide.

SIGNIFICANCE AND IMPACT OF THE STUDY

Overall this study highlights that any microbial data, used in either predictive microbiology or risk assessment, must take account of the sensitivity and associated performance of the methods employed, in order to make an accurate reflection of the true microbiology of the examined sample.

Solution-phase, parallel synthesis and pharmacological evaluation of acylguanidine derivatives as potential sodium channel blockers

Solution-phase synthesis of various acylguanidine derivatives and the evaluation of a small library of compounds as potential sodium channel blockers are described.

Wheelchair propulsion biomechanics: implications for wheelchair sports

The aim of this article is to provide the reader with a state-of-the-art review on biomechanics in hand rim wheelchair propulsion, with special attention to sport-specific implications. Biomechanical studies in wheelchair sports mainly aim at optimising sport performance or preventing sport injuries. The sports performance optimisation question has been approached from an ergonomic, as well as a skill proficiency perspective. Sports medical issues have been addressed in wheelchair sports mainly because of the extremely high prevalence of repetitive strain injuries such as shoulder impingement and carpal tunnel syndrome. Sports performance as well as sports medical reflections are made throughout the review. Insight in the underlying musculoskeletal mechanisms of hand rim wheelchair propulsion has been achieved through a combination of experimental data collection under realistic conditions, with a more fundamental mathematical modelling approach. Through a synchronised analysis of the movement pattern, force generation pattern and muscular activity pattern, insight has been gained in the hand rim wheelchair propulsion dynamics of people with a disability, varying in level of physical activity and functional potential. The limiting environment of a laboratory, however, has hampered the drawing of sound conclusions. Through mathematical modelling, simulation and optimisation (minimising injury and maximising performance), insight in the underlying musculoskeletal mechanisms during wheelchair propulsion is sought. The surplus value of inverse and forward dynamic simulation of hand rim stroke dynamics is addressed. Implications for hand rim wheelchair sports are discussed. Wheelchair racing, basketball and rugby were chosen because of the significance and differences in sport-specific movement dynamics. Conclusions can easily be transferred to other wheelchair sports where movement dynamics are fundamental.

Psychological distress, social support, and disease activity in patients with inflammatory bowel disease

OBJECTIVES

The objectives of this study were to compare the psychological status of patients in active and inactive disease states, to assess social support, and to identify correlates of psychological distress in patients with inflammatory bowel disease (IBD).

METHODS

This cross-sectional study was conducted in 200 patients (mean age 36.7 yr [SD = 14.8], 119 [59.5%] female) with long-standing IBD who were seen in tertiary care. Psychosocial assessments included psychological distress (Symptom Checklist-90R), social support (Social Support Questionnaire-6), perceived stress (Perceived Stress Scale-10), and recent minor stressful events (Weekly Stress Inventory). Disease activity was assessed with the Harvey Bradshaw Index.

RESULTS

Patients reported higher levels of satisfaction with social support and smaller network sizes compared with normative values. Using multiple linear regression, the independent correlates of psychological distress (p = 0.0001; adjusted R2 = 0.62) were as follows: active disease (p = 0.0234), less time since diagnosis (p = 0.0012), and greater number (p = 0.0001) and impact of stressful events (p = 0.0003). A statistically significant interaction term (p = 0.0171) revealed that the relationship between psychological distress and perceived stress changes depending on the level of satisfaction with social support. For patients with low levels of perceived stress, satisfaction with social support did not affect levels of psychological distress. However, for patients who experienced moderate to high levels of perceived stress, high satisfaction with social support decreased the level of psychological distress.

CONCLUSIONS

These findings suggest that strategies aimed at improving social support can have a favorable impact on psychological distress and, ultimately, can improve health outcomes in patients with IBD.

2-Amino-5-chloro-1,3-benzoxazol-3-ium 2-(3,4-dichlorophenoxy)acetate

The 1:1 organic salt of the title compound, C(7)H(6)ClN(2)O(+). C(8)H(5)Cl(2)O(3)(-) or [(2-ABOX)(3,4-D)], comprises the two constituent molecules associated by an R(2)(2)(8) graph-set interaction through the carboxylate group of 3,4-D across the protonated N/N sites of 2-ABOX [N.O 2.546 (3) and 2.795 (3) A]. Cation/anion pairs associate across an inversion centre forming discrete tetramers via an additional three-centre hydrogen-bonding association from the latter N amino proton to a phenoxy O atom [N.O 3.176 (3) A] and a carboxylate O atom [N.O 2.841 (3) A]. This formation differs from the polymeric hydrogen-bonded chains previously observed for adduct structures of 2-ABOX with carboxylic acids.

QTc interval (cardiac repolarization): lengthening after meals

Weight reduction, either by dietary or surgical means, is associated with prolongation of the heart rate corrected QT interval (QTc = QT/R-R0.5) and, on occasion, sudden death. Screening subjects with obesity before weight loss for prolonged QTc intervals is an accepted practice, although at present, there are no guidelines for whether subjects should be fasting before electrocardiogram (EKG) evaluation. The aim of this study was to test the hypothesis that EKG QTc interval duration is independent of meal ingestion. The hypothesis was tested in 11 healthy subjects who ingested a 500-kcal formula meal. A small decrease in absolute QT interval and a steady decline in R-R interval were observed for up to 60 minutes after formula ingestion. The QTc interval increased above baseline at 15 minutes (p < 0.007) after meal, a change that persisted for the 1-hour postmeal observation period. Spectral analysis of EKG R-R intervals (low-/high-frequency amplitude ratio) indicated a change in cardiac autonomic flow after meal ingestion. The QTc interval did not lengthen and R-R low-/high-frequency amplitude ratio remained unchanged in eight subjects evaluated in a similar manner but in whom isovolumic amounts of water replaced the meal. These observations suggest that (1) cardiac repolarization changes with fasting and feeding, (2) the QTc interval is influenced by meal intake, and (3) the autonomic nervous system may play a role in meal-related QTc changes. These findings have implications for the evaluation of patients with obesity before starting and during weight loss treatment.

Beckwith-Wiedemann syndrome: dental management

Beckwith-Wiedemann syndrome (BWS) comprises multiple congenital anomalies with a risk of childhood tumours. Macroglossia is the most common manifestation. Two cases are presented to illustrate the importance of early referral and the role of preventive dentistry.

Activation of glutamatergic neurotransmission by ketamine: a novel step in the pathway from NMDA receptor blockade to dopaminergic and cognitive disruptions associated with the prefrontal cortex

Subanesthetic doses of ketamine, a noncompetitive NMDA receptor antagonist, impair prefrontal cortex (PFC) function in the rat and produce symptoms in humans similar to those observed in schizophrenia and dissociative states, including impaired performance of frontal lobe-sensitive tests. Several lines of evidence suggest that ketamine may impair PFC function in part by interacting with dopamine neurotransmission in this region. This study sought to determine the mechanism by which ketamine may disrupt dopaminergic neurotransmission in, and cognitive functions associated with, the PFC. A thorough dose-response study using microdialysis in conscious rats indicated that low doses of ketamine (10, 20, and 30 mg/kg) increase glutamate outflow in the PFC, suggesting that at these doses ketamine may increase glutamatergic neurotransmission in the PFC at non-NMDA glutamate receptors. An anesthetic dose of ketamine (200 mg/kg) decreased, and an intermediate dose of 50 mg/kg did not affect, glutamate levels. Ketamine, at 30 mg/kg, also increased the release of dopamine in the PFC. This increase was blocked by intra-PFC application of the AMPA/kainate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione CNQX. Furthermore, ketamine-induced activation of dopamine release and impairment of spatial delayed alternation in the rodent, a PFC-sensitive cognitive task, was ameliorated by systemic pretreatment with AMPA/kainate receptor antagonist LY293558. These findings suggest that ketamine may disrupt dopaminergic neurotransmission in the PFC as well as cognitive functions associated with this region, in part, by increasing the release of glutamate, thereby stimulating postsynaptic non-NMDA glutamate receptors.

Neuroprotective use-dependent blockers of Na+ and Ca2+ channels controlling presynaptic release of glutamate

We have originated a family of N,N'-disubstituted guanidines that block the voltage-activated Ca2+ and Na+ channels governing glutamate release. These compounds, CNS 1237 (N-acenaphthyl-N'-methoxynaphthyl guanidine) and its analogues, are "use dependent" in their ability to attenaute neurotransmitter release: they block glutamate release with greater efficacy under conditions of persistent or repetitive depolarization, as would be encountered under pathophysiological circumstances, relative to their ability to block glutamate release elicited by brief, transient depolarizations more characteristic of normal physiological release events in nonischemic brain. Using electrophysiological and rapid kinetic methods, we have differentiated the use-dependent block of the relevant Na+ and Ca2+ channels governing neurotransmitter release from the mechanism of channel antagonism exhibited by, respectively, the substituted guanidine Na+ channel blocker tetrodotoxin (TTX) and venom peptide Ca2+ antagonists. To characterize use-dependent Na+ channel block by CNS 1237, we have employed whole-cell voltage-clamp recordings from a Chinese hamster ovary (CHO) cell line expressing cloned mammalian type II Na+ channels. These experiments demonstrated that, in contrast to the actions of TTX under the same conditions, the potency of Na+ channel block by CNS 1237 is greatly enhanced by depolarizing stimuli in a frequency-dependent manner. Ca2+ channel-activated glutamate release from brain nerve terminal preparations was measured with approximately 300 msec time resolution over a 5-second period of high K(+)-depolarization, using a rapid superfusion technique. CNS 1237 and analogues, at 1-3 microM, accelerated the decay of glutamate release by 40-70%, reflecting depolarization-induced enhancement of block. In contrast, blockade of glutamate release by the Ca2+ channel antagonist peptide toxins omega-aga IV-A (from spider venom) and omega-conotoxin M-VII-C (from cone snail venom) exhibited "reverse-use-dependence:" at concentrations of 0.3 microM, which blocked the initial amplitude of glutamate release by 40-60%, the decay time constant for glutamate release was significantly increased, indicating depolarization-induced relief of block. These findings establish that CNS 1237 and other members of this compound series are use-dependent blockers of the voltage-activated ion channels governing glutamate release. Studies of CNS 1237 in the rat middle cerebral artery occlusion (MCAO) focal stroke model have indicated infarct size reduction comparable to that observed by the same investigators for the glutamate release blocker (BW 619C89 (Burroughs-Wellcome, now in clinical development). Maximal infarct size reduction is achieved with a 3-mg/kg bolus followed by a 4-hour infusion of 0.75 mg/kg/hr.(ABSTRACT TRUNCATED AT 400 WORDS)

Impairment of fibrinolysis by streptokinase, urokinase and recombinant tissue-type plasminogen activator in the presence of radiographic contrast agents

OBJECTIVES

The purpose of this study was to determine whether an adverse interaction exists between radiographic contrast agents and thrombolytic drugs.

BACKGROUND

Coronary thrombosis may occur in the setting of unstable angina and after coronary angioplasty. However, the use of thrombolytic drugs in the setting of unstable angina has not been beneficial and, in one large trial of angioplasty in patients with unstable angina, was associated with an increased incidence of ischemic complications and abrupt closure. The reasons for these results are not clear. Coronary arteriography was performed in many of these trials, and it is known that fibrin structure and assembly are altered by radiographic contrast agents.

METHODS

Blood samples were obtained from patients before (n = 25) and after (n = 20) angiography using iohexol. Blood samples obtained before angiography were tested for response to streptokinase (10 and 100 IU/ml), urokinase (100, 200 and 500 IU/ml) and recombinant tissue-type plasminogen activator (rt-PA) (100 and 1,000 IU/ml) and the results measured. Iohexol, diatrizoate or ioxaglate (4% by volume) was added to separate aliquots of the baseline sample, and the test was repeated. Blood samples obtained after angiography were tested in a similar manner.

RESULTS

The onset of lysis at baseline by rt-PA at 1,000 IU/ml occurred at 72 +/- 8.2 s (mean +/- SD) and was markedly delayed in the presence of diatrizoate (527 +/- 181.7 s, p < 0.001) or iohexol (460 +/- 197.0 s, p < 0.001) but not ioxaglate. At 100 IU/ml, there was no lysis detected with rt-PA after the addition of any contrast agent. The addition of a contrast agent caused similar delays in the onset of lysis by urokinase and streptokinase; similar to rt-PA, the effect was smaller at higher concentrations of drug. In vivo blood samples obtained from the patient after angiography showed delays in the onset of lysis by rt-PA and urokinase but not streptokinase.

CONCLUSIONS

These data demonstrate that radiographic contrast agents impede fibrinolysis. This previously undescribed interaction was demonstrated using an in vitro test system, but these findings may have clinical relevance when thrombolytic drugs are used at the time of angiography.

New CNS-specific calcium antagonists

Ischemic insults to the brain in stroke or traumatic brain injury produce excessive release of glutamate from depolarized nerve terminals. This excessive glutamate release in turn stimulates massive calcium entry into nerve cells, activating a biochemical cascade that results in cell death. A major pathway of calcium entry into depolarized nerve cells is through voltage-sensitive, high threshold calcium channels. A large fraction of this calcium entry is mediated through "R-type" calcium channels, channels resistant to blockage by dihydropyridine calcium antagonists such as nimodipine. A newly discovered compound derived from spider venom, CNS 2103, antagonizes both R-type channels and dihydropyridine-sensitive ("L-type") calcium channels. This broad spectrum of action, coupled with selectivity for calcium channels over other classes of voltage-sensitive and ligand-gated ion channels, makes CNS 2103 an interesting lead for development of drugs to treat ischemic brain injury. Activation of presynaptic ("N-type") calcium channels in nerve terminals is a primary cause of excessive neurotransmitter release in brain ischemia. Prevention of glutamate release by blockade of N-type channels in glutamatergic nerve terminals may, at an early stage in the pathophysiological cascade, abort the process leading to nerve cell death. Cambridge NeuroScience has developed a novel rapid kinetic approach for monitoring glutamate release from brain nerve terminals in vitro, and this has led to CNS 1145, a substituted guanidine that selectively blocks a kinetic component of calcium-dependent glutamate release mediated by persistent depolarization. Additional evidence suggests that CNS 1145 antagonizes presynaptic N-type calcium channels, and this may account at least in part for its ability to block glutamate release.

The importance of congenital hypertrophy of the retinal pigment epithelium in familial adenomatous polyposis

We describe a family with familial adenomatous polyposis (FAP) and congenital hypertrophy of the retinal pigment epithelium (RPE). Three of five members with FAP showed flat, well-demarcated, round to oval pigmented patches of congenital hypertrophy of the RPE. We stress the importance of congenital hypertrophy of the RPE as a clinical marker in identifying patients with FAP since they are at risk for cancer.

The inlet patch: heterotopic gastric mucosa in the upper esophagus

Careful endoscopic survey of the upper esophagus indicates that a visually recognizable patch of gastric mucosa is grossly visible much more commonly than is generally recognized. Sixteen instances were found in 420 sequential endoscopies, an incidence of 3.8%. The gastric mucosal rest presented as a velvety red patch with a distinct border, varying from a few millimeters in diameter to complete encirclement of the esophagus, was occasionally paired, and was found either at or just below the upper esophageal sphincter. In all instances except one the patch consisted of gastric-type mucosa containing both parietal and chief cells; in the single exception, it consisted of gastric-type mucous glands without parietal cells. Although larger patches can be shown to function under stimulation (they produce a local drop in pH with pentagastrin stimulation), there are usually no apparent associated clinical symptoms.

A comparison of tube leukocyte adherence inhibition assay and standard physical methods for diagnosing colorectal cancer

In vitro antitumor immunity, measured by means of a tube leukocyte adherence inhibition (LAI) assay, was able to demonstrate early colorectal cancer in cases yet undiagnosed. Testing 106 patients attending a colonoscopy clinic, we found that nine of 15 (60%) patients with colorectal cancer were LAI-positive. The nine included: five of six with Dukes' A and B; one of two with Dukes' C; and three of seven with Dukes' D lesions. Of 58 patients without colon neoplasia, one had a positive test. By contrast, barium enema results were diagnostic for 13 of 15 (87%) cases and colonoscopy for 11 of 15 (73%). There were 32 colon polyps discovered by means of barium enema and colonoscopy. Of 13 adenomas removed, four had stimulated positive LAI responses. Of another 19 polyps not removed two incited positive LAI responses. Two patients with histories of recurrent adenomas were LAI-positive, though only one had a new polyp that could be detected by means of barium enema. For a procedure to be of diagnostic value for a given disease, sensitivity and specificity must be at least 1.0. If this sum is 2.0, the test is ideal. The sum of sensitivity and specificity for the tube LAI assay, barium enema, and colonoscopy were 1.58, 1.87, and 1.73, respectively, for colorectal cancer; 1.81, 2.0, and 2.0, respectively, for early colorectal cancer; and 1.42, 1.77, and 1.55 respectively, for advanced colorectal cancer. In this limited series of patients, the barium enema seems to be superior to the tube LAI assay for diagnosing colorectal cancer, but the difference in sensitivity and specificity is not statistically valid by the paired chi square test. The results of this study shows conclusively, that the tube LAI is of diagnostic value and suggest its use for evaluating suspected cases, especially early ones, of colorectal cancer.

Nondestructive determination of pacemaker sense amplifier passband

Most artificial cardiac pacemakers incorporate sense amplifiers to detect intrinsic heart activity in order to eliminate the possibility of competition between the artificial and natural pacemakers. When artificial pacemakers fail prematurely, the failure cause should be determined so that systematic failure modes can be identified and corrected. The failure analysis of any sophisticated electronic product is difficult; failure analysis of a cardia pacemaker is complicated by the sealing technologies encountered. Because access to the circuitry of implantable devices is impeded by the packaging of the device, and because the packaging may have influenced the failure, nondestructive testing techniques must be used extensively. This paper reports on a method for nondestructive determination of the pacemaker sense amplifier with a (sin x)/x waveform to which a continuous wave sinusoid is added. The amplifier passband is characterized by increasing the frequency of the sinusoid in increments of 5 Hertz and determining the amplifier sensitivity at each step.