An intricate network of reactions is involved in matching energy supply with demand in the heart. This complexity arises because energy production both modulates and is modulated by the electrophysiological and contractile activity of the cardiac myocyte. Here, we present an integrated mathematical model of the cardiac cell that links excitation-contraction coupling with mitochondrial energy generation. The dynamics of the model are described by a system of 50 ordinary differential equations. The formulation explicitly incorporates cytoplasmic ATP-consuming processes associated with force generation and ion transport, as well as the creatine kinase reaction. Changes in the electrical and contractile activity of the myocyte are coupled to mitochondrial energetics through the ATP, Ca2+, and Na+ concentrations in the myoplasmic and mitochondrial matrix compartments. The pseudo steady-state relationship between force and oxygen consumption at various stimulus frequencies and external Ca2+ concentrations is reproduced in both model simulations and direct experiments in cardiac trabeculae under normoxic conditions, recapitulating the linearity between cardiac work and respiration in the heart. Importantly, the model can also reproduce the rapid time-dependent changes in mitochondrial NADH and Ca2+ in response to abrupt changes in workload. The steady-state and dynamic responses of the model were conferred by ADP-dependent stimulation of mitochondrial oxidative phosphorylation and Ca2+ -dependent regulation of Krebs cycle dehydrogenases, illustrating how the model can be used as a tool for investigating mechanisms underlying metabolic control in the heart.

A three-dimensional (3D) diffusion-weighted imaging (DWI) method for measuring cardiac fiber structure at high spatial resolution is presented. The method was applied to the ex vivo reconstruction of the fiber architecture of seven canine hearts. A novel hypothesis-testing method was developed and used to show that distinct populations of secondary and tertiary eigenvalues may be distinguished at reasonable confidence levels (P ≤ 0.01) within the canine ventricle.

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Pulmonary function tests (PFTs) provide important quantitative information about lung function and can be used to elucidate pathologic conditions responsible for respiratory symptoms, assess the severity and course of disease, and evaluate the patient for suitability and timing for lung transplantation. They are typically used in tandem with chest imaging, along with other ancillary data, to arrive at a specific diagnosis. PFTs may provide the radiologist with clues to the diagnosis and grading of a wide variety of pulmonary diseases. In this review, the authors discuss the clinical use of PFTs, their major components, and important measurements and graphical representations that are essential for understanding and interpreting the results. The key components of PFT panels-static lung volumes, dynamic lung function (spirometry), and diffusion capacity-are explained. The authors present a general algorithmic approach for problem solving, with recognition of common patterns of results (obstructive, restrictive, mixed, nonspecific, and normal). Pulmonary diseases from each of the major patterns and chest imaging are illustrated, and correlations between particular PFT results and disease severity and morphology at imaging are examined. Common pitfalls encountered during interpretation are also highlighted. A basic understanding of the mechanics of PFTs, characteristic patterns in important diseases, and correlation between lung function and imaging findings may assist the radiologist in diagnosis and follow-up of key pulmonary diseases and strengthen the radiologist's role as part of a multidisciplinary diagnostic team. Online supplemental material is available for this article. RSNA, 2017.

The permanganate redox reaction is a powerful system with potential to reach tumouricidal temperatures. The reagent volumes, concentrations, injection order, and substrate choice allow a measure of control over the reaction.

Drug loadable bioresorbable microspheres (BRMS) are specially designed for the treatment of hypervascular tumors through arterial embolization. These microspheres consist of carboxymethyl chitosan crosslinked with carboxymethyl cellulose, and are available at different size ranges varying from 50 to 900 µm in diameter. Similar to commercially available non-resorbable drug eluting microspheres, LC Bead microspheres (LCB), BRMS were capable of loading more than 99 % of doxorubicin, an anticancer drug, from the solution within 2 h with highly similar kinetics (difference factor f = 0.36; similarity factor f = 97.99). Doxorubicin loaded BRMS exhibited the highest elution rate in the 30 % ethanol aqueous solution saturated with potassium chloride, and the elution time depended on the ratio between the amount of loaded BRMS and the volume of elution media. After injection through microcatheters, BRMS have a higher recovery rate of the microsphere weight than LCB (90.96 vs. 79.63 %, P = 0.026). Although loaded BRMS eluted more drug into the injection medium than loaded LCB (8.63 vs. 3.80 %, P = 0.0015), there was no significant difference in the drug delivery rate between BRMS and LCB (83.88 vs. 86.65 %, P = 0.504). This study compares the loading capability as well as the drug delivery rate of BRMS and a commercial product under a condition simulating a transcatheter arterial chemoembolization procedure and demonstrates the potential of drug loaded BRMS for the treatment of hypervascular tumors such as hepatocellular carcinoma.