Vaccine strain Listeria monocytogenes bacteremia occurring 31 months after immunization.

Background: Listeria monocytogenes is a food-borne, facultative intracellular bacterium that causes severe diseases such as sepsis and meningoencephalitis in immunocompromised hosts. Because it stimulates robust T-lymphocyte-mediated responses, attenuated L. monocytogenes are candidate vaccine vectors for tumor immunotherapy.

The impact of ovariectomy on calcium homeostasis and myofilament calcium sensitivity in the aging mouse heart.

This study determined whether deficiency of ovarian estrogen starting very early in life promoted age-associated Ca(2+) dysregulation and contractile dysfunction in isolated ventricular myocytes. Myocytes were isolated from anesthetized C57BL/6 female mice. Animals received an ovariectomy or sham-operation at one month and were aged to ~24 months.

A procedure for creating a frailty index based on deficit accumulation in aging mice.

This study developed an approach to quantify frailty with a frailty index (FI) and investigated whether age-related changes in contractions, calcium transients, and ventricular myocyte length were more prominent in mice with a high FI. The FI combined 31 variables that reflect different aspects of health in middle-aged (∼12 months) and aged (∼30 months) mice of both sexes. Aged animals had a higher FI than younger animals (FI = 0.

Ovariectomy enhances SR Ca²⁺ release and increases Ca²⁺ spark amplitudes in isolated ventricular myocytes.

This study compared Ca(2+) homeostasis in ventricular myocytes from 8-month-old female C57BL/6J mice that had either a bilateral ovariectomy (OVX) or a sham surgery at 3 weeks of age. Cells were loaded with fura-2 and field-stimulated or voltage-clamped with steps to membrane potentials between -40 and +80 mV (37°C). Peak Ca(2+) transients increased by two-fold in OVX myocytes when compared to sham, and Ca(2+) transient rates of rise and decay were faster in OVX cells.

Effect of age on cardiac excitation-contraction coupling.

1. Cardiovascular diseases most commonly occur in the elderly and are a frequent cause of disability or death. However, the effect of age itself on cardiac function is not well understood.