Cardiac troponin in ischemic cardiomyocytes: Intracellular decrease before onset of cell death

Aim

Cardiac troponin I (cTnI) and T (cTnT) are the most important biomarkers in the diagnosis of acute myocardial infarction (AMI). Nevertheless, they can be elevated in the absence of AMI. It is unclear if such elevations represent irreversible cardiomyocyte-damage or leakage from viable cardiomyocytes. Our objective is to evaluate whether cTn is released from viable cardiomyocytes in response to ischemia and to identify differences in the release of cTn and its molecular forms.

Methods and results

HL-1 cardiomyocytes (mouse) were subjected to ischemia (modeled by anoxia with glucose deprivation). The total contents and molecular forms of cTn were determined in culture media and cell lysates. Cell viability was assessed from the release of lactate dehydrogenase (LDH). Before the release of LDH, the intracellular cTn content in ischemic cells decreased significantly compared to control (52% for cTnI; 23% for cTnT) and was not matched by a cTn increase in the medium. cTnI decreased more rapidly than cTnT, resulting in an intracellular cTnT/cTnI ratio of 25.5 after 24 h of ischemia. Western blots revealed changes in the relative amounts of fragmented cTnI and cTnT in ischemic cells.

Conclusions

HL-1 cardiomyocytes subjected to simulated ischemia released cTnI and cTnT only in combination with the release of LDH. We find no evidence of cTn release from viable cardiomyocytes, but did observe a significant decrease in cTn content, before the onset of cell death. Intracellular decrease of cTn in viable cardiomyocytes can have important consequences for the interpretation of cTn values in clinical practice.     

Advances in light-curing units: four generations of LED lights and clinical implications for optimizing their use: Part 2. From present to future

The first part of this series of two described the history of light curing in dentistry and developments in LED lights since their introduction over 20 years ago. Current second- and third-generation LED light units have progressively replaced their halogen lamp predecessors because of their inherent advantages. The background to this, together with the clinical issues relating to light curing and the possible solutions, are outlined in the second part of this article. Finally, the innovative features of what may be seen as the first of a new fourth-generation of LED lights are described and guidance is given for the practitioner on what factors to consider when seeking to purchase a new LED light activation unit. Clinical Relevance: Adequate curing in depth is fundamental to clinical success with any light-activated restoration. To achieve this goal predictably, an appropriate light source needs to be combined with materials knowledge, requisite clinical skills and attention to detail throughout the entire restoration process. As dentists increasingly use light-cured direct composites to restore large posterior restorations they need to appreciate the issues central to effective and efficient light curing and to know what to look for when seeking to purchase a new light-curing unit.     

Imaging-Based 3-Dimensional Printing for Improved Maxillofacial Presurgical Planning: A Single Center Case Series

Purpose3-D printing is an increasingly widespread technology that allows physical models to be constructed based on cross-sectional medical imaging data. We sought to develop a pipeline for production of 3-dimensional (3-D) models for presurgical planning and assess the value of these models for surgeons and patients.MethodsIn this institutional review board–approved, single-center case series, participating surgeons identified cases for 3-D model printing, and after obtaining patient consent, a 3-D model was produced for each of the 7 participating patients based on preoperative cross-sectional imaging. Each model was given to the surgeon to use during the surgical consent discussion and preoperative planning. Patients and surgeons completed questionnaires evaluating the quality and usefulness of the models.ResultsThe 3-D models improved surgeon confidence in their operative approach, influencing the choice of operative approach in the majority of cases. Patients and surgeons reported that the model improved patient comprehension of the surgery during the consent discussion, including risks and benefits of the surgery. Model production time was as little as 4 days, and the average per-model cost was $350.Conclusions3-D printed models are useful presurgical tools from both surgeon and patient perspectives. Development of local hospital-based 3-D printing capabilities enables model production with rapid turnaround and modest cost, representing a value-added service for radiologists to offer their surgical colleagues.     

Age-dependent cognitive decline and amygdala pathology in alpha-synuclein transgenic mice

Intraneuronal alpha-synuclein (alphaSYN) inclusions constitute the hallmark lesions of a number of neurodegenerative diseases, including Parkinson's disease and dementia with Lewy bodies. In a transgenic mouse model expressing mutant [A30P]alphaSYN under control of the pan-neuronal Thy1 promoter, motor impairment became significant beyond 17 months of age. Cognitive performance was measured in the Morris water maze and upon fear conditioning. At 4 months of age, transgenic mice performed like controls. However, performance in these tasks was significantly impaired in (Thy1)-h[A30P]alphaSYN mice at 12 months of age. After completion of the cognition tests, mice were sacrificed and the regional distribution of neuropathology was examined. In contrast to 4 months old animals, 12 months old transgenic mice showed alpha-synucleinopathy in several brain regions, including the central nucleus of the amygdala, which is involved in cognitive behavior of mice, and is susceptible to alphaSYN pathology in human patients. Thus, age-dependent fibrillization of alphaSYN in specific cortical regions concomitant with cognitive decline may reflect dementia with Lewy bodies in a transgenic mouse model.