The Effect of Recurrent Hypoglycemia on Mental Flexibility

A major side-effect of intensive insulin replacement therapy, is recurrent hypoglycemia (RH). Clinical and experimental evidence suggest that RH may be associated with deficits in higher cognitive processes; specifically, in judgment and mental flexibility, processes believed to be mediated in large part by the medial prefrontal cortex. The present study investigates the effects of short-term RH on mental flexibility in rats. Animals underwent food restriction and were extensively handled and habituated. Prior to testing animals were randomly assigned to one of four groups with varying levels of RH. Animals were then tested for two consecutive days on a set-shift maze task designed to be analogous to the Wisconsin-Card Sorting Task used in humans as a task of frontal cortex-based rule-learning and flexibility processes. The Set-Shift maze is a rotating plus maze with a food well at the end of each arm, where each arm varies with respect to two stimulus dimensions: brightness (smooth or dark) and texture (rough or smooth). Day 1 of testing required each animal to learn a contingency rule: food reward is associated with one value of a single dimension. On day two, the reward contingency switched dimensions such that for example on day 1, if brightness was rewarded, on day 2, an aspect of texture would be rewarded. Performance on day 2 requires the animal to both (i) inhibit the previously learnt behavior, and (ii) employ a novel mental strategy to acquire the new rule, testing mental flexibility. We investigated the effects of RH on brain metabolite and neurotransmitter levels during behavioral testing using in vivo microdialysis. Post-testing, brain tissue was harvested, sectioned, and stained for proper probe placement verification and future analysis. Results indicate that on day two of testing, animals tested while euglycemic but with prior RH required significantly more trials to reach criterion as compared to controls (f=3.673; p=.029). Acute hypoglycemic status had no effect on maze performance, possibly because of the increased Effect of Recurrent Hypoglycemia on Cognition 4 motivation for receiving a food reward while hypoglycemic. These findings suggest that a history of prior hypoglycemia may lead to impaired mental flexibility and decision-making, a result which is consistent with anecdotal clinical findings and which has important implications for diabetics undergoing insulin replacement therapy. Further research may be necessary to develop more effective treatment regimens that reduce the risk of RH

Nutrient Addition Effects on Phytoplankton Communities in the Amazon River Plume

The types and abundance of phytoplankton is largely controlled by availability of sunlight and bioavailable nutrients. Phytoplankton require essential nutrients including nitrate, phosphate, and silicate to grow, so understanding the role of these macronutrients in limiting the growth phytoplankton communitiesand the way this may differ depending on community compositionis key to understanding the controls on phytoplankton biomass and community structure. We aimed to explore how the availability of these nutrients affects the health and composition of phytoplankton communities by conducting a series of nutrient amendment experiments (NAEs) with samples from the Western Tropical North Atlantic, which is heavily influenced by the nutrient-rich, low salinity waters of the Amazon River Plume. These experiments, conducted at five locations in and around the plume, provide greater resolution and further our understanding about the ways nutrients affect communities in dynamic coastal regions

Magnetic navigation in percutaneous coronary and non-coronary interventions

There is no question that Percutaneous Coronary Intervention has revolutionized the way we manage coronary artery disease. Over the past two decades we have witnessed maturity in several techniques and equipment enabling the interventional cardiologist to manage lesions that have previously been entirely in the domain of the cardiac surgeon. Despite these remarkable achievements there still remain lesions that are complex enough to create a challenge in the most experienced hands.The inherent tortuosity in complex vascular anatomies, branching segments and chronically occluded vessel have been all associated with lower procedural success and higher complication rates when compared to the “straight forward vessels”. The Magnetic Navigation System (MNS) is a novel and versatile technology that allows the re-orientation of a wire within the patient’s body. This unique ability means that the “trial and error” method of externally re-shaping the tip of the wire and re-engaging the vessel can be effectively eliminated. As such previously “unreachable areas” in the heart or within the vascul

Audition in sciaenid fishes with different swim bladder-inner ear configurations

We investigated how morphological differences in the auditory periphery of teleost fishes may relate to hearing capabilities. Two species of western Atlantic sciaenids were examined: weakfish (Cynoscion regalis, Block and Schneider) and spot (Leiostomus xanthurus, Lacepede). These species differ in the anatomical relationship between the swim bladder and the inner ear. In weakfish, the swim bladder has a pair of anterior horns that terminate close to the ear, while there are no extensions of the swim bladder in spot. Thus, the swim bladder in spot terminates at a greater distance from the ear when compared to weakfish. With the use of the auditory brainstem response technique, Cynoscion regalis were found to detect frequencies up to 2000 Hz, while Leiostomus xanthurus detected up to 700 Hz. There were, however, no significant interspecific differences in auditory sensitivity for stimuli between 200 and 700 Hz. These data support the hypothesis that the swim bladder can potentially expand the frequency range of detection

Assessing the validity of the Triage Risk Screening Tool in a third world setting

Background: Social risk is rarely evaluated in older emergency department (ED) patients, although its identification can reduce re-attendance. Objectives: This study assessed the diagnostic accuracy of the Triage Risk Screening Tool (TRST) in the ED of a developing country. Methods: The diagnostic accuracy of TRST to detect elders at risk was compared to routine clinical evaluation, using a comprehensive evaluation by an experienced social worker as the ‘gold standard’. The inter-rater reliability of the TRST was assessed on a separate cohort of patients prior to the main study. Results: The sensitivity of the TRST was 94.7% vs 55.6% for physician assessment (p = 0.025). The TRST had good inter-rater reliability (Cohen’ Kappa = .882), and physicians found it easy to use. Conclusion: The TRST provides a rapid means of assessing risk in older ED attenders. This study confirmed the validity of this screening tool in a third world setting

Falls in Older People: Comparing Older and Younger Fallers in a Developing Country

Purpose While falls are common in older people, causing significant mortality and morbidity, this phenomenon has not been extensively studied in the Caribbean. This study aimed to compare falls in older and younger people in this setting. Methods We conducted a prospective observational study of older trauma patients in Trinidad, comparing older and younger patients sustaining falls. Results 1432 adult trauma patients were included (1141 aged 18 - 64 years and 291 aged 65 years and older). Older fallers were more likely to be female (66.7% vs 47.2%; p <.001), suffer from multiple pre-existing diseases (24.7% vs 2.4%; p <.001) and take multiple medications (16.1% vs 0.8%; p <.001). They also sustained more severe injuries and presented with higher acuity than younger fallers. Admission rates were higher among older fallers (29.9% vs 13.1%; p <.001). Conclusions In our study, older patients who fell were a distinct group from younger falls victims, with unique demographic, clinical and injury related characteristics. Their increased risk of injury within the home, coupled with their propensity for more severe injuries made them a high risk patient group. More research is needed to better understand this patient group and plan specific preventive interventions

Depression in diabetic patients presenting to the emergency department in Trinidad and Tobago – a hidden epidemic

The likelihood of depression in diabetics presenting to the Emergency Department in developing countries is unknown. The aim of this study was to determine the prevalence of undiagnosed depression among diabetic patients presenting to the Emergency Department in Trinidad and Tobago, and to determine the risk factors associated with depression in these patients. The prevalence of depression was 46.2%, of which 76.1% had mild depression, 20.6% moderate depression and 3.3% severe depression. Depressed patients were more likely to be Indo Trinidadian (69.7%), married (61.8%) and working in the public sector (42.3%). Factors independently associated with depression included lower education level (p=0.003), and a history of co-existing heart disease (p=0.048), myocardial infarction (p=0.04) or other co-morbidities (p=0.010). Depressed patients had higher HbA1c% values (p<0.0001), and were less likely to adhere to meal plans (p=0.015) and exercise regimes (p=0.028). Depression is an unrecognised epidemic among diabetics in the Trinidad and Tobago. This study suggests that screening for depression among diabetics in the Emergency Department may be a useful method of identifying these patients. Additionally, the association between poor diabetic control and depression in these patients suggests the need for more research into this phenomenon

Factors affecting mortality in major trauma patients in Trinidad and Tobago – a view from the developing world

Background: There is little data on major trauma in the developing world. This study investigated the characteristics and outcomes of seriously injured patients in Trinidad and Tobago, using TRISS methodology. Conclusion: Multiple factors influence mortality in major trauma patients in Trinidad and Tobago, including age, co-morbidities and injury mechanism. TRISS methodology accurately predicted survival in this population. A multi-centre trial is required to validate these findings

Presenting symptoms of acute coronary syndrome in older and younger adults in Trinidad & Tobago

BACKGROUND AND AIM: Acute Coronary Syndrome (ACS) is a major cause of mortality in Trinidad and Tobago. As life expectancy increases, Emergency Departments in Trinidad and Tobago are admitting more older patients (age ≥ 65). Previous studies have demonstrated differences in the presenting symptoms between older and younger patients with ACS. However, to our knowledge, no such work has been done on older patients in the developing world. The aim of this study was to determine the differences in the reported symptoms of ACS between the older patients (age ≥ 65) and younger adults (age 18 – 64) in the ED. The primary objective was to compare the differences in frequency of symptoms of ACS between the older and younger adults. A secondary objective was to determine if differences in reported symptoms also exist between older men and older women. CONCLUSIONS: This study demonstrates significant differences in symptoms between older and younger patients as well as between older men and women. Clinical assessment of older patients with ACS should be tailored to their common presenting features. Further work is needed to develop a clinical assessment tool for older patients with ACS that accounts for differences in presentation

Are older fallers different? Comparing older fallers and non-fallers in a developing country

Objectives: Falls are common in older people, causing significant mortality and morbidity, but little is known about this phenomenon in developing countries. This study aimed to investigate falls in older people in the developing world, comparing fallers with other trauma patients. Methods: We conducted a prospective observational study of older trauma patients in Trinidad over a four-month period, comparing falls victims with other trauma patients, in relation to their demographic, pre-morbid and injury characteristics. Results: A total of 439 older trauma patients (aged 65 years) were included. Fallers were older (median age 75 years (interquartile range 65–89 years) vs. 70 years (interquartile range 65–79 years) in non-fallers). Overall, 65.2% of fallers were female, compared to 43.7% of non-fallers. Fallers were more likely to suffer from multiple pre-existing diseases, with 29.8% having comordibities, compared to 9.7% of non-fallers. Fallers were also more likely to be on multiple medications: 7.1% were on five medications, compared to no non-fallers. Fallers also sustained more severe injuries and presented with higher acuity than non-fallers. Admission and referral rates were higher among fallers compared to other trauma patients (59.9% vs. 30.4%). Conclusions: Older patients who fall are a distinct group from other older trauma patients, with unique demographic, clinical and injury-related characteristics. This information is useful in planning preventive and management strategies for these patients