Localized rest and stress human cardiac creatine kinase reaction kinetics at 3 T.

Changes in the kinetics of the creatine kinase (CK) shuttle are sensitive markers of cardiac energetics but are typically measured at rest and in the prone position. This study aims to measure CK kinetics during pharmacological stress at 3 T, with measurement in the supine position. A shorter "stressed saturation transfer" (StreST) extension to the triple repetition time saturation transfer (TRiST) method is proposed. We assess scanning in a supine position and validate the MR measurement against biopsy assay of CK activity. We report normal ranges of stress CK forward rate (kfCK ) for healthy volunteers and obese patients. TRiST measures kfCK in 40 min at 3 T. StreST extends the previously developed TRiST to also make a further kfCK measurement during <20 min of dobutamine stress. We test our TRiST implementation in skeletal muscle and myocardium in both prone and supine positions. We evaluate StreST in the myocardium of six healthy volunteers and 34 obese subjects. We validated MR-measured kfCK against biopsy assays of CK activity. TRiST kfCK values matched literature values in skeletal muscle (kfCK  = 0.25 ± 0.03 s-1 vs 0.27 ± 0.03 s-1 ) and myocardium when measured in the prone position (0.32 ± 0.15 s-1 ), but a significant difference was found for TRiST kfCK measured supine (0.24 ± 0.12 s-1 ). This difference was because of different respiratory- and cardiac-motion-induced B0 changes in the two positions. Using supine TRiST, cardiac kfCK values for normal-weight subjects were 0.15 ± 0.09 s-1 at rest and 0.17 ± 0.15 s-1 during stress. For obese subjects, kfCK was 0.16 ± 0.07 s-1 at rest and 0.17 ± 0.10 s-1 during stress. Rest myocardial kfCK and CK activity from LV biopsies of the same subjects correlated (R = 0.43, p = 0.03). We present an independent implementation of TRiST on the Siemens platform using a commercially available coil. Our extended StreST protocol enables cardiac kfCK to be measured during dobutamine-induced stress in the supine position.

Surface anatomy and surface landmarks for thoracic surgery.

A thorough knowledge of thoracic anatomy is of fundamental importance to the thoracic surgeon. Surface anatomy is an often-neglected component of traditional topographic anatomic teaching, but a proper understanding of the relationship of surface features to deeper structures is invaluable in the clinical assessment of a patient and in the interpretation of radiologic imaging. Familiarity with thoracic surgical landmarks is a prerequisite for the successful placing of a thoracic incision. Knowledge of the intrathoracic anatomy and level of the diaphragm based on surface landmarks is useful for interventional procedures, such as tube thoracostomy. Knowledge of the chest wall musculature is essential in the use of muscle flaps for reconstruction.

Prognostic factors in resected satellite-nodule T4 non-small cell lung cancer.

BACKGROUND: The 1997 non-small cell lung cancer staging revisions assigned a T4 descriptor to satellite nodules in the primary tumor lobe. We reviewed our experience of satellite-nodule T4 non-small cell lung cancer following these revisions and evaluated prognostic factors for this group. METHODS: All patients who underwent resection of non-small cell lung cancer between April 1997 and June 2005 with satellite nodule(s) confirmed at pathologic examination were identified from our institutional Lung Tumor Registry. Case notes and pathology reports were reviewed and data collected on possible prognostic factors. Survival was modeled using the Kaplan-Meier method, and survival differences between groups were analyzed using the log-rank test. RESULTS: From 1,276 non-small cell lung cancer patients who underwent resection, 137 were staged pT4, and 35 were T4-satellite nodules. Median follow-up was 25 months (range, 1 to 102 months). Median main tumor size was 3.0 cm (range, 1 to 9.8 cm). Adenocarcinoma or bronchioloalveolar carcinoma was the predominant histologic diagnosis (n = 28; 80%). One-, 3- and 5-year survival was 86%, 69%, and 57%, respectively; median survival was 68 months. During the same period, 137 patients undergoing resection for all T4 lesions had a 1-, 3-, and 5-year survival of 68%, 53%, and 18%, respectively. Adenocarcinoma or bronchioloalveolar carcinoma histologic diagnosis (adenocarcinoma or bronchioloalveolar carcinoma versus squamous, 75% versus 67% 3-year survival; p = 0.0026), female gender (66% versus 49% for males, 5-year survival; p = 0.041), and absence of vascular invasion (no invasion versus vascular invasion, 74% versus 20% 5-year survival; p = 0.0101) were significant predictors of better survival. CONCLUSIONS: Survival for resected T4 non-small cell lung cancer with satellite nodule(s) in the primary lobe is better than for other T4 lesions, and the T4 descriptor may unduly upstage these cases. The current T4 descriptor represents a heterogeneous population.

Selective down-regulation of sub-endocardial ryanodine receptor expression in a rabbit model of left ventricular dysfunction.

Defective sarcoplasmic reticulum (SR) Ca2+ handling is evident in cardiomyopathy and may be mediated by selective dysregulation of SR Ca2+ handling proteins. To assess whether regulation of SR Ca2+ release may vary regionally within the normal and diseased heart, left ventricular transmural expression and activity of the ryanodine receptor (RyR2) was studied in a rabbit coronary artery ligation model of left ventricular dysfunction (LVD). Tissue/cells were isolated from both the sub-endocardial and subepicardial layers of the left ventricular free wall from sham-operated and coronary artery ligated rabbit hearts. Three independent methods were used to study alterations in RyR2 mRNA (real-time quantitative PCR (RT-PCR)) and protein expression (quantitative immunoblotting and [3H] ryanodine binding). These biochemical data were compared with functional measurements of fractional SR Ca2+ release from both of these regions. Data from RT-PCR revealed lower RyR2 mRNA levels in the sub-endocardium compared with subepicardium in both experimental groups with the reduction being significantly lower in the sub-endocardium from the LVD group. Quantitative analysis of RyR2 protein levels revealed the same expression patterns. Calsequestrin mRNA and protein levels showed no significant changes. This study demonstrates a lower expression level of RyR2 in the sub-endocardium of the left ventricle of rabbit hearts and is the first to show a further specific reduction in LVD. There is a corresponding decrease in fractional SR Ca2+ release in cells isolated from the sub-endocardium of hearts from the LVD group, relating these selective biochemical alterations to changes in function.

Cardiac expression of the cystic fibrosis transmembrane conductance regulator involves novel exon 1 usage to produce a unique amino-terminal protein.

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a chloride channel present in many cells. In cardiomyocytes, we report that multiple exon 1 usage and alternative splicing produces four CFTR transcripts, with different 5'-untranslated regions, CFTR(TRAD-139), CFTR(-1C/-1A), CFTR(-1C), and CFTR(-1B). CFTR transcripts containing the novel upstream exons (exons -1C, -1B, and -1A) represent more than 90% of cardiac expressed CFTR mRNA. Regulation of cardiac CFTR expression, in response to developmental and pathological stimuli, is exclusively due to the modulation of CFTR(-1C) and CFTR(-1C/-1A) expression. Upstream open reading frames have been identified in the 5'-untranslated regions of all CFTR transcripts that, in conjunction with adjacent stem-loop structures, modulate the efficiency of translation initiation at the AUG codon of the main CFTR coding region in CFTR(TRAD-139) and CFTR(-1C/-1A) transcripts. Exon -1A, only present in CFTR(-1C/-1A) transcripts, encodes an AUG codon that is in-frame with the main CFTR open reading frame, the efficient translation of which produces a novel CFTR protein isoform with a curtailed amino terminus. As the expression of this CFTR transcript parallels the spatial and temporal distribution of the cAMP-activated whole-cell current density in normal and diseased hearts, we suggest that CFTR(-1C/-1A) provides the molecular basis for the cardiac cAMP-activated chloride channel. Our findings provide further insight into the complex nature of in vivo CFTR expression, to which multiple mRNA transcripts, protein isoforms, and post-transcriptional regulatory mechanisms are now added.

Post-transcriptional regulation of the cystic fibrosis gene in cardiac development and hypertrophy.

Eukaryotic gene expression, reflected in the amount of steady-state mRNA, is regulated at the post-transcriptional level. The 5'-untranslated regions (5'-UTRs) of some transcripts contain cis-acting elements, including upstream open reading frames (uORFs), that have been identified as being fundamental in modulating translation efficiency and mRNA stability. Previously, we demonstrated that uORFs present in the 5'-UTR of cystic fibrosis transmembrane conductance regular (CFTR) transcripts expressed in the heart were able to modulate translation efficiency of the main CFTR ORF. Here, we show that the same 5'-UTR elements are associated with the differential stability of the 5'-UTR compared to the main coding region of CFTR transcripts. Furthermore, these post-transcriptional mechanisms are important factors governing regulated CFTR expression in the heart, in response to developmental and pathophysiological stimuli.