Improving the clinical efficiency of T2 mapping of ligament integrity

Current MR methods use T₂^? relaxation time as a surrogate measure of ligament strength. Currently, a multi-echo voxel-wise least squares fit is the gold standard to create T₂^? maps; however, the post-processing is time-intensive and serves as a stopgap for clinical use. The study objective was to determine if an alternative method could improve post-processing time without sacrificing fidelity of T₂^? values for eventual translational use in the clinic. Using a 6 echo FLASH sequence, three different methods were used to determine intact posterior cruciate ligament (PCL) median T₂^? Two of these methods utilized a voxel-wise method to establish T₂^? maps: (1) a current “gold standard” method using a voxel-wise 6 echo least-squares fit (6LS) and (2) a voxel-wise 2 echo point T₂^? determination (2MM). The third method used median ligament signal intensity and a single nonlinear least-squares fit (6LS_ROI) instead of a voxel-wise basis. The resulting median T₂^? values of the PCL and computational time were compared. The median T₂^? values were 42% higher using the 2MM compared to the 6LS method (p<0.0001). However, a strong correlation was found for the median T₂^? values between the 2MM and 6LS methods (R²=0.80). The median T₂^? values were not significantly different between the 6LS and 6LS_ROI methods (p=0.519). Using the 2MM (which provides a regional map) and the 6LS_ROI (which efficiently provides the median T₂^? value) methods in tandem would take only minutes of post-processing computational time compared to the 6LS method (~540 min), and hence would facilitate clinical application of T₂^? maps to predict ligament structural properties as a patient outcome measure.     

Ecdysteroids during embryonation of eggs of Ascaris suum

1. The optimal temperature for in vitro development of fertilized eggs of Ascaris suum was 24 degrees C. 2. Samples (2 X 10(7) eggs) were obtained from in vitro embryonating cultures every 3 days for 4 weeks; lipids were extracted, partially purified, fractionated with HPLC and analyzed for ecdysteroids by radioimmunoassay. 3. Free ecdysone and 20-hydroxyecdysone (20-HE) were at low levels (less than 20 pg) in freshly excised eggs and rose to maximal values on day 6 of embryonation. 4. Conjugated ecdysone and conjugated 20-HE rose to maximal values on day 9. 5. Both free and conjugated ecdysteroids were undetectable from days 15 to 27 of cultivation. 6. These profiles indicate that ecdysteroids might have a selective role in nematode embryonation and/or tanning of the egg shell.     

Cloning of a rabbit erythroid-cell-specific lipoxygenase mRNA

We report the isolation of cDNA recombinants representing part of the rabbit reticulocyte (immature red blood cell, RBC) lipoxygenase (LOX) mRNA. One cDNA predicts an amino acid (aa) sequence matching exactly the unique N-terminal 30-aa sequence of the purified enzyme. Further, the reticulocyte mRNA, hybrid-selected by this recombinant, can be translated in vitro to give a polypeptide that comigrates with the purified reticulocyte LOX and is recognized by affinity-purified anti-RBC LOX polyclonal antibodies. Southern blotting experiments hybridising the RBC LOX cDNAs available to total rabbit genomic DNA digested with various restriction enzymes gives a fairly simple hybridisation pattern under moderate stringency conditions: moreover, the same pattern is obtained with a cloned fragment of genomic DNA containing the RBC LOX gene. This indicates that the RBC LOX gene is unique in the genome and seems not to be very closely related to the genes encoding the other tissue LOXs. We also show by Northern transfer/hybridisation experiments that the RBC LOX mRNA is expressed only in the red cell lineage but not in white blood cells (bone marrow or spleen) or in other non-erythroid cells tested (e.g., brain and lung).