Regional ischemia in hypertrophic Langendorff-perfused rat hearts

Myocardial hypertrophy decreases the muscle mass-to-vascularization ratio, thereby changing myocardial perfusion. The effect of these changes on myocardial oxygenation in hypertrophic Langendorff-perfused rat hearts was measured using epimyocardial NADH videofluorimetry, whereby ischemic myocardium displays a high fluorescence intensity. Hypertrophic hearts, in contrast to control hearts, developed ischemic areas during oxygen-saturated Langendorff perfusion. Reoxygenation of control hearts after a hypoxic episode resulted in a swift decrease of fluorescence in a heterogeneous pattern of small, evenly dispersed, highly fluorescent patches. Identical patterns could be evoked by occluding capillaries with microspheres 5.9 micrometer in diameter. Ten seconds after reoxygenation there were no more dysoxic areas, whereas reoxygenation in hypertrophic hearts showed larger ischemic areas that took significantly longer to return to normoxic fluorescence intensities. Hypothesizing that the larger areas originate at a vascular level proximal to the capillary network, we induced hypoxic patterns by embolizing control hearts with microspheres 9.8 and 15 micrometer in diameter. The frequency distribution histograms of these dysoxic surface areas matched those of hypertrophic hearts and differed significantly from those of hearts embolized with 5.9-micrometer microspheres. These results suggest the existence of areas in hypertrophic Langendorff-perfused hearts with suboptimal vascularization originating at the arteriolar and/or arterial level

Imminent ischemia in normal and hypertrophic Langendorff rat hearts; effects of fatty acids and superoxyde dismutase monitored by NADH surface fluorescence

Hypertrophic hearts contain areas of hypoperfusion which can be visualized by increased NADH surface fluorescence during in vitro perfusion without oxygen-carrying particles under constant pressure and pacing. By contrast, fluorescence remained low when non-hypertrophic hearts were used instead. When during perfusion of normal hearts the pH of the medium was lowered from 7.5 to 7.0, areas of high fluorescence appeared in a few minutes. The high fluorescent areas under conditions of cardiac hypertrophy or pH 7.0 perfusion could be reduced by addtion of superoxide dismutase. It indicates that oxygen free radicals interfere with proper flow regulation in areas of low pH. Fluorescence in hypertrophic hearts also diminished during addition of albumin-bound oleate to the standard, glucose-containing, medium. This is in agreement with our earlier findin of fatty acid protection from acidosis-initiated loss of capillary flow (Biochim. Biophys. Acta, 1033 (1990) 214–218). In contrast to low concentrations of free fatty acids, high concentrations interfere with tissue oxygenation. This has been illustrated by the use of 1 mM octanoate, which after a few min caused the appearance of high fluorescent areas. We conclude that decompensation of flow in hypoperfused areas of heart, as occurs in hypertrophy, may be stimulated by acidosis and oxygen free radicals

Prognostic Implications of Lateral Lymph Nodes in Rectal Cancer:A Population-Based Cross-sectional Study with Standardized Radiological Evaluation after Dedicated Training

BACKGROUND: There is an ongoing discussion regarding the prognostic implications of the presence, short-axis diameter, and location of lateral lymph nodes. OBJECTIVE: To analyze lateral lymph node characteristics, the role of downsizing on restaging MRI, and associated local recurrence rates for patients with cT3-4 rectal cancer after MRI re-review and training. DESIGN: Retrospective population-based cross-sectional study. SETTINGS: This collaborative project was led by local investigators from surgery and radiology departments in 60 Dutch hospitals. PATIENTS: A total of 3057 patients underwent rectal cancer surgery in 2016: 1109 had a cT3-4 tumor located ≤8 cm from the anorectal junction, of whom 891 received neoadjuvant therapy. MAIN OUTCOME MEASURES: Local recurrence and (ipsi) lateral local recurrence rates. RESULTS: Re-review identified 314 patients (35%) with visible lateral lymph nodes. Of these, 30 patients had either only long-stretched obturator (n = 13) or external iliac (n = 17) nodes, and both did not lead to any lateral local recurrences. The presence of internal iliac/obturator lateral lymph nodes (n = 284) resulted in 4-year local recurrence and lateral local recurrence rates of 16.4% and 8.8%, respectively. Enlarged (≥7 mm) lateral lymph nodes (n = 122) resulted in higher 4-year local recurrence (20.8%, 13.1%, 0%; p &lt;.001) and lateral local recurrence (14.7%, 4.4%, 0%; p &lt; 0.001) rates compared to smaller and no lateral lymph nodes, respectively. Visible lateral lymph nodes (HR 1.8 [1.1-2.8]) and enlarged lateral lymph nodes (HR 1.9 [1.1-3.5]) were independently associated with local recurrence in multivariable analysis. Enlarged lateral lymph nodes with malignant features had higher 4-year lateral local recurrence rates of 17.0%. Downsizing had no impact on lateral local recurrence rates. Enlarged lateral lymph nodes were found to be associated with higher univariate 4-year distant metastasis rates (36.4% vs 24.4%; p = 0.021), but this was not significant in multivariable analyses (HR 1.3 [0.9-1.]) and did not worsen overall survival. LIMITATIONS: This study was limited by the retrospective design and total number of patients with lateral lymph nodes. CONCLUSIONS: The risk of lateral local recurrence due to (enlarged) lateral lymph nodes was confirmed, but without the prognostic impact of downsizing after neoadjuvant therapy. These results point toward the incorporation of primary lateral lymph node size into treatment planning. See Video Abstract.</p

Myocardial Microcirculation and Mitochondrial Energetics in the Isolated Rat Heart

Normal functioning of myocardium requires adequate oxygenation, which in turn is dependent on an adequate microcirculation. NADH-fluorimetry enables a direct evaluation of the adequacy of tissue oxygenation while the measurement of quenching of Pd-porphyrine (PpIX) phosphorescence enables quantitative measurement of microvascular pO2. Combination of these two techniques provides information about the relation between microvascular oxygen content and parenchymal oxygen availability in Langendorff hearts. In normal myocardium there is heterogeneity at the microcirculatory level resulting in the existence of microcirculatory weak units, originating at the capillary level, which reoxygenate the slowest upon reoxygenation after an episode of ischemia. Sepsis and myocardial hypertrophia alter the pattern of oxygen transport whereby the microcirculation is disturbed at the arteriolar/arterial level. NADH fluorimetry also reveals a disturbance of mitochondrial oxygen availability in sepsis. Furthermore it is shown that these techniques can also be applied to various organs and tissues in viv

Increase of cardiac work is associated with decrease of mitochondrial NADH

In this study we investigated the effect of work and substrate supply on mitochondrial NADH/NAD+ using epicardial autofluorescence in rat hearts perfused according to Langendorff. To avoid vasoconstrictor effects during high work output, nitroprusside-containing Tyrode solution was used. Photobleaching was avoided by using discontinuous ultraviolet excitation for NADH fluorescence measurements. To increase work, heartbeat rate was raised from 5 to 7 Hz, and concomitantly left ventricular pressure was raised stepwise from 0 to +/- 90 mmHg. During substrate-limited (5.5 mM glucose) perfusions, increase in O2 consumption (3.5 +/- 0.4 mumol.min-1.g-1, mean +/- SE, n = 6) caused by increase of heartbeat rate was associated with a significant decrease of NADH fluorescence (-31 +/- 2.5%, mean +/- SE, n = 6). During perfusions with 10 mM pyruvate increase of O2 consumption (3.6 +/- 0.7 mumol.min-1.g-1, mean +/- SE, n = 6) was associated with significant decrease of NADH fluorescence (-20 +/- 2.6%, mean +/- SE, n = 6). These results suggest that a rise in mitochondrial NADH/NAD+ is not the primary stimulus for increase in respiration and that changes of mitochondrial NADH/NAD+ are secondary to changes in O2 consumptio