Gloveport hernioscopy

It can be difficult to exclude occult, necrotic bowel in incarcerated herniae that reduce prior to emergent surgical exploration without resorting to further abdominal wall incisions. This case illustrates the Gloveport hernioscopy technique to identify necrotic small intestine that had spontaneously reduced in a man with a strangulated umbilical hernia. This minimally invasive technique allowed a multichannel examination of the peritoneal cavity without any further insult to the abdominal wall.

Myocardial substrate metabolism in obesity

Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end-stage systolic heart failure. Obesity causes changes in cardiac metabolism, which make ATP production and utilization less efficient, producing functional consequences that are linked to the increased rate of heart failure in this population. As a result of the increases in circulating fatty acids and insulin resistance that accompanies excess fat storage, several of the proteins and genes that are responsible for fatty acid uptake and metabolism are upregulated, and the metabolic machinery responsible for glucose utilization and oxidation are inhibited. The resultant increase in fatty acid metabolism, and the inherent alterations in the proteins of the electron transport chain used to create the gradient needed to drive mitochondrial ATP production, results in a decrease in efficiency of cardiac work and a relative increase in oxygen usage. These changes in cardiac mitochondrial metabolism are potential therapeutic targets for the treatment and prevention of obesity-related heart failure.

Effects of weight loss on myocardial energetics and diastolic function in obesity

A reduced myocardial phosphocreatine/adenosine triphosphate (PCr/ATP) ratio is linked to both diastolic dysfunction and heart failure. Although obesity is well known to cause diastolic dysfunction a link to impaired cardiac energetics has only recently been established. We assessed whether or not long-term weight loss in obesity, which is known to reduce mortality, is accompanied by both improved cardiac energetics and diastolic function. Normal weight (BMI 22 ± 2; n = 18) and obese subjects (BMI 34 ± 4; n = 13) underwent cine-MRI (1.5 Tesla) to determine left ventricular diastolic function using volume-time curve analysis, and (31)P-MR spectroscopy (3 Tesla) to assess cardiac energetics (PCr/ATP ratio). Obese subjects (n = 13) underwent repeat assessment after 1 year of supervised weight loss. Obesity, in the absence of identifiable cardiovascular risk factors, was associated with significantly impaired myocardial high energy phosphate metabolism (PCr/ATP ratio, normal; 2.03 ± 0.27 vs. obese; 1.58 ± 0.47, p = 0.002) and significantly lower peak diastolic filling rate (normal; 4.8 ± 0.8 vs. obese; 3.8 ± 0.7 EDV/s, p = 0.01). Weight loss (on average 9 kg, 55% excess weight) over 1 year resulted in a 24% increase in PCr/ATP ratio (p = 0.01) and an 18% improvement in peak diastolic filling rate (p = 0.01). Myocardial PCr/ATP ratio remained positively correlated with peak diastolic filling rate after weight loss (r = 0.63, p = 0.02). In obesity, weight loss improves impaired cardiac energetics and myocardial relaxation. Improved myocardial energetics appear to play a key role in diastolic functional recovery accompanying weight loss.

Perinatal autopsy rates at the University Hospital of the West Indies: 2002-2008

OBJECTIVES

High perinatal autopsy rates are necessary for institutional management protocols and national policy-making. This study reviews perinatal autopsy rates and factors affecting these rates at the University Hospital of the West Indies.

METHOD

All perinatal deaths (stillborn infants > or = 24 weeks gestation or 500 g; early neonatal deaths ie 0-7 days old) at the University Hospital of the West Indies, between January 2002 and December 2008, were reviewed retrospectively, using the annual perinatal audit records. The annual autopsy rates were calculated and the reasons why autopsies were not done examined.

RESULTS

The average stillbirth (SB) autopsy rate was 59.6% (range 51.9 - 76.7%), while that for early neonatal deaths (ENDs) was 47.9% (range 34.4 - 63.2), with an overall average perinatal autopsy rate of 54.0% (range 42.2 - 62.2). Autopsies were requested in 79.3% and 51.7% of SBs and ENDs, respectively. Of those requested, 81.7% were done (75.2% stillbirths; 92.5% ENDs). In the ENDs, failure to request an autopsy was predominantly noted in premature infants weighing < 1000 g (75.2% of those not requested). In stillbirths, the reasons for failure to request were largely unknown with failure to gain permission accounting for only 20.3% of these cases.

CONCLUSIONS

The average annual perinatal autopsy rate at the University Hospital of the West Indies between 2002 and 2008 was 54.0%. This is below the internationally recommended rate of 75%. Failure to request an autopsy was the most significant factor contributing to this. The reasons for this are not entirely clear and require further study.

Poster - Thur Eve - 20: Serial FDG 4DPET imaging during radiotherapy in advanced lung cancer patients

The availability of respiratory synchronized PET (4DPET) imaging has enabled more accurate analysis of metabolic response since motion blur is minimized. We present our preliminary analysis of serial FDG 4DPET images acquired at weeks 0, 2, 4, and 7 during radiotherapy of seven stage II-III NSCLC patients. The tumor and nodal PTV of the week 0 images restrained a 4DPET image thresholding algorithm to automatically contour SUV levels ranging from 20 to 80% of the maximum SUV, creating an intensity volume histogram (IVH) for each week. These contours allowed analysis of PET volumes and standard PET metrics such as SUV_max and SUV_mean . We found a trend for decreasing SUV_max and SUV_mean over a treatment course in both the tumor and nodal regions. On average, the SUV_max within the tumor decreased by 17±13% (1 SD) after 2 weeks, 30±13% after 4 weeks, and 39±19% after 7 weeks of radiotherapy. Decreasing volume trends were also observed in the 20 to 80% max SUV autocontours, ranging from 26±29% to 50±40% respectively, over 7 weeks of treatment. Only one patient demonstrated an increase in FDG uptake within the tumor volume between week 0 and week 2 of treatment, and was also the only patient to recur locally at 3 months following treatment. Changes in tumor metabolism over the course of advanced NSCLC radiotherapy are quantifiable with serial FDG 4DPET imaging. Preliminary analysis suggests that variations in these trends could be useful in identifying non-responding patients that may require an alternative radiotherapeutic approach.

Stereotactic body radiotherapy (SBRT) for non-small cell lung cancer (NSCLC): is FDG-PET a predictor of outcome?

BACKGROUND AND PURPOSE

Distant metastases are the dominant mode of failure after stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC). The primary study objective was to evaluate if the maximum standardized uptake value (SUV(max)) on pre-treatment FDG-PET/CT predicted clinical outcomes. Secondary objectives were to correlate 3-month post-SBRT SUV(max) and change in SUV(max) with outcomes.

MATERIALS AND METHODS

Consecutive patients with medically inoperable early-stage NSCLC and an FDG-PET/CT scan before (n=82) and 3 months after (n=62) SBRT.

RESULTS

Median follow up was 2 years. On univariate analysis baseline SUV(max) predicted for distant failure (p=0.0096), relapse free survival (RFS) (p=0.037) and local failure (p=0.044). On multivariate analysis baseline SUV(max) predicted for RFS (p=0.037). Baseline SUV(max) of above 5 was the most statistically significant cut off point for predicting distant failure (p=0.0002). Baseline SUV(max) ≥4.75 (median) was correlated with a higher risk of distant failure (p=0.012) and poorer RFS (p=0.04). Patients with a post-SBRT SUV(max) ≥2 and a reduction of <2.55 had a significantly higher rate of distant failure.

CONCLUSIONS

Pre-SBRT SUV(max) on FDG-PET/CT correlated most strongly with distant failure. A cut off of ≥5 was the most significant. Post-SBRT SUV(max) ≥2 and a reduction of <2.55 were associated with a higher risk of distant failure.

Mice expressing a human K(ATP) channel mutation have altered channel ATP sensitivity but no cardiac abnormalities

AIMS/HYPOTHESIS

Patients with severe gain-of-function mutations in the Kir6.2 subunit of the ATP-sensitive potassium (K(ATP)) channel, have neonatal diabetes, muscle hypotonia and mental and motor developmental delay-a condition known as iDEND syndrome. However, despite the fact that Kir6.2 forms the pore of the cardiac K(ATP) channel, patients show no obvious cardiac symptoms. The aim of this project was to use a mouse model of iDEND syndrome to determine whether iDEND mutations affect cardiac function and cardiac K(ATP) channel ATP sensitivity.

METHODS

We performed patch-clamp and in vivo cine-MRI studies on mice in which the most common iDEND mutation (Kir6.2-V59M) was targeted to cardiac muscle using Cre-lox technology (m-V59M mice).

RESULTS

Patch-clamp studies of isolated cardiac myocytes revealed a markedly reduced K(ATP) channel sensitivity to MgATP inhibition in m-V59M mice (IC(50) 62 μmol/l compared with 13 μmol/l for littermate controls). In vivo cine-MRI revealed there were no gross morphological differences and no differences in heart rate, end diastolic volume, end systolic volume, stroke volume, ejection fraction, cardiac output or wall thickening between m-V59M and control hearts, either under resting conditions or under dobutamine stress.

CONCLUSIONS/INTERPRETATION

The common iDEND mutation Kir6.2-V59M decreases ATP block of cardiac K(ATP) channels but was without obvious effect on heart function, suggesting that metabolic changes fail to open the mutated channel to an extent that affects function (at least in the absence of ischaemia). This may have implications for the choice of sulfonylurea used to treat neonatal diabetes.

Igf2 ligand dependency of Pten(+/-) developmental and tumour phenotypes in the mouse

The tumour suppressor PTEN is a key negative regulator of the PI3K-Akt pathway, and is frequently either reduced or lost in human tumours. Murine genetic studies have confirmed that reduction of Pten promotes tumourigenesis in multiple organs, and demonstrated dependency of tumour development on the activation of downstream components such as Akt. Insulin-like growth factors (IGFs) act via IGF1R to activate the PI3K-Akt pathway, and are commonly upregulated in cancer. A context-dependent interplay between IGFs and PTEN exists in normal tissue and tumours; increased IGF2 ligand supply induces Pten expression creating an autoregulatory negative feedback loop, whereas complete loss of PTEN may either cooperate with IGF overexpression in tumour promotion, or result in desensitisation to IGF ligand. However, it remains unknown whether neoplasia associated with Pten loss is dependent on upstream IGF ligand supply in vivo. We evaluated this by generation of Pten^+/− mice with differing allelic dosage of Igf2, an imprinted gene encoding the potent embryonic and tumour growth factor Igf2. We show that biallelic Igf2 supply potentiates a previously unreported Pten^+/− placental phenotype and results in strain-dependent cardiac hyperplasia and neonatal lethality. Importantly, we also show that the effects of Pten loss in vivo are modified by Igf2 supply, as lack of Igf2 results in extended survival and delayed tumour development while biallelic supply is associated with reduced lifespan and accelerated neoplasia in females. Furthermore, we demonstrate that reduction of PTEN protein to heterozygote levels in human MCF7 cells is associated with increased proliferation in response to IGF2, and does not result in desensitisation to IGF2 signalling. These data indicate that the effects of Pten loss at heterozygote levels commonly observed in human tumours are modified by Igf2 ligand, and emphasise the importance of the evaluation of upstream pathways in tumours with Pten loss.