Anabolic steroids can lead to an expansion of the cardiac muscle, which can cause heart attacks.

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He has managed to reprogram mouse connective-tissue cells so that they develop into cardiac muscle cells, and has tested them in the hearts of mice that have had heart attacks.

ECONOMIST: Stem cells and medicine: Repairing broken hearts | The

Alternatively, chemicals they secrete may stimulate changes in cells already present in the heart a suggestion encouraged by the work of Paul Riley at University College, London, who has (in mice) stimulated stem cells which were already present to turn into cardiac muscle by adding a protein called thymosin beta 4 that throws a crucial genetic switch in stem cells, and thus activates them.

ECONOMIST: Stem cells and medicine: Repairing broken hearts | The

Engaging in new behaviors to enhance our health like regular exercise will lead to improved muscle tone, cardiac function, stronger bones, better respiratory function, more balanced emotions and calmer nerves, greater mental clarity and a better night's sleep.

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Normally, orderly waves of electric activity pass through the cardiac tissue, causing the heart muscle to contract.

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The long-term hope is to treat patients with some sort of stem cell that could turn into beating heart muscle and replace dead cardiac tissue with fully functioning new cells.

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These cells can differentiate into many different cell lines, including cardiac, neuro, or even skeletal muscle.

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They found that the stem cells produced growth factors that traveled to the heart, in addition to stimulating the muscle itself to make growth factors that also improved cardiac function.

CNN: Stem cells may offer promise for damaged hearts