Procollagen alpha2 mRNA is significantly different from procollagen alpha1(I) mRNA in size or secondary structure.

The fractionation of fetal calf tendon messenger RNA in 85 percent formamide sucrose gradients shows a separation of the mRNAs coding for pro α1(I) and pro α2 chains of type I collagen. This difference in sedimentation in denaturing gradients suggests that pro α2 mRNA is approxmately 1000 bases shorter than pro α1(I) mRNA. However, such a size difference is significantly greater than would be predicted from consideration of the size of the polypeptide chains coded for by these mRNAs, and thus, residual secondary structure in the mRNAs may contribute to these apparent size differences.     

Validation of a rodent model of source memory

Source memory represents the origin (source) of information. Recently, we proposed that rats (Rattus norvegicus) remember the source of information. However, an alternative to source memory is the possibility that rats selectively encoded some, but not all, information rather than retrieving an episodic memory. We directly tested this ‘encoding failure’ hypothesis. Here, we show that rats remember the source of information, under conditions that cannot be attributed to encoding failure. Moreover, source memory lasted at least seven days but was no longer present 14 days after studying. Our findings suggest that long-lasting source memory may be modelled in non-humans. Our model should facilitate attempts to elucidate the biological underpinnings of source memory impairments in human memory disorders such as Alzheimer''s disease.     

Are there increased periprocedural complications with the MRI-conditional Medtronic Revo SureScan Pacing System?

Background

The use of magnetic resonance imaging (MRI)-conditional permanent pacemakers has increased significantly. In this meta-analysis, we examine the safety of MRI-conditional pacing systems in comparison with conventional systems.

Methods

An electronic search was performed using major databases, including studies that compared the outcomes of interest between patients receiving MRI-conditional pacemakers (MRI group) versus conventional pacemakers (control group).

Results

Six studies (5 retrospective and 1 prospective non-randomised) involving 2,118 adult patients were identified. The MRI-conditional pacemakers, deployed in 969 patients, were all from a single manufacturer (Medtronic Pacing System with 5086 leads). The rate of pacemaker lead dislodgement (atrial and ventricular) was significantly higher in the MRI group (3% vs. 1%, OR 2.47 (95% CI 1.26; 4.83), p?=?0.008). The MRI group had a significantly higher rate of pericardial complications (2% vs. 1%, OR 4.23 (95% CI 1.18; 15.10), p?=?0.03) and a numerically higher overall complication rate in comparison with the conventional group (6% vs. 3%, OR 2.02 (95% CI 0.88; 4.66), p?=?0.10) but this was not statistically significant.

Conclusions

In this meta-analysis, the rates of pacemaker lead dislodgement and pericardial complications were significantly higher with the Medtronic MRI-conditional pacing system.