Frozen human cardiac muscle was weighed and homogenized using a small glass Dounce homogenizer
(D8938, 2 mL; Sigma Aldrich) at room temperature in different volumes of pooled human serum with a free [Ca.sup.2+] concentration of 1.25 mmol/L at the ratios specified in Fig.
Lesion crusts and biopsy material may be soaked in 3 volumes buffer and solubilized by 10-12 pestle strokes in a Dounce homogenizer
, while fecal material may be suspended by vortexing with glass beads in 3-9 volumes of distilled water.
At targeted stages of development, embryos were frozen, rinsed twice in cold tank water, dissolved in 1 mL of TRI REAGENT, and transferred to a Dounce Homogenizer
(Fisher Scientific, Pittsburgh, PA), previously washed with chloroform.