Background— Spontaneous Ca 2+ release from the sarcoplasmic reticulum (SR) can generate afterdepolarizations, and these have the potential to initiate arrhythmias. Therefore, an association may exist between spontaneous SR Ca 2+ release and initiation of atrial fibrillation (AF), but this has not yet been reported. Methods and Results— Spontaneous Ca 2+ release from the SR, manifested as Ca 2+ sparks and Ca 2+ waves, was recorded with confocal microscopy in atrial myocytes isolated from patients with and those without AF. In addition, the spontaneous inward current associated with Ca 2+ waves was measured with the use of the perforated patch-clamp technique. The Ca 2+ spark frequency was higher in 8 patients with AF than in 16 patients without (6.0±1.2 versus 2.8±0.8 sparks/mm per second, P <0.05). Similarly, the spontaneous Ca 2+ wave frequency was greater in patients with AF (2.8±0.5 versus 1.1±0.3 waves/mm per second, P <0.01). The spontaneous inward current frequency was also higher in 10 patients with AF than in 13 patients without this arrhythmia (0.101±0.028 versus 0.031±0.007 per second, P <0.05, at a clamped potential of −80 mV). In contrast, both the Ca 2+ released from the SR and the Na + -Ca 2+ exchange rate induced by a rapid caffeine application were comparable in patients with and without AF. Conclusions— The observed increase in spontaneous Ca 2+ release in patients with AF probably is due to an upregulation of the SR Ca 2+ release channel activity, which may contribute to the development of AF.

Fifteen Holstein male calves were randomly assigned to 1 of 3 dietary treatments according to age and body weight (BW) to determine the effects of feeding different forages sources on rumen fermentation and gastrointestinal tract (GIT) development. Treatments consisted of a starter (20% crude protein, 21% neutral detergent fiber) fed alone (CON) or supplemented with alfalfa (AH) or with oat hay (OH). All calves received 2L of milk replacer (MR) at 12.5% dry matter twice daily until 49 d of age. Calves received 2L of the same MR from 50 to 56 d of age and were weaned at 57 d of age. Individual starter, forage, and MR intakes were recorded daily and BW was recorded weekly. A rumen sample was taken weekly to determine rumen pH and volatile fatty acid concentrations. Three weeks after weaning, animals were harvested and each anatomical part of the GIT was separated and weighed with and without contents. Rumen pH was lower in CON than in OH and AH calves. Furthermore, acetate proportion in the rumen liquid tended to be greater in AH than in CON and OH treatments. Total GIT weight, expressed as a percentage of BW, tended to be greater in AH compared with the other 2 treatments. Rumen tissue tended to weigh more in CON than in OH animals. Animals with access to forage tended to have a greater expression of monocarboxylate transporter 1 than CON calves. In conclusion, calves supplemented with oat hay have a better rumen environment than calves offered no forage and do not have an increased gut fill.

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Background: Many enzymes of industrial interest are not in the market since they are bioproduced as bacterial inclusion bodies, believed to be biologically inert aggregates of insoluble protein.