Protein arginine N-methyltransferase 2 plays a noncatalytic role in the histone methylation activity of PRMT1.

Protein arginine N-methyltransferases are a family of epigenetic enzymes responsible for monomethylation or dimethylation of arginine residues on histones. Dysregulation of protein arginine N-methyltransferase activity can lead to aberrant gene expression and cancer. Recent studies have shown that PRMT2 expression and histone H3 methylation at arginine 8 are correlated with disease severity in glioblastoma multiforme, hepatocellular carcinoma, and renal cell carcinoma. In this study, we explore a noncatalytic mechanistic role for PRMT2 in histone methylation by investigating interactions between PRMT2, histone peptides and proteins, and other PRMTs using analytical and enzymatic approaches. We quantify interactions between PRMT2, peptide ligands, and PRMT1 in a cofactor- and domain-dependent manner using differential scanning fluorimetry. We found that PRMT2 modulates the substrate specificity of PRMT1. Using calf thymus histones as substrates, we saw that a 10-fold excess of PRMT2 promotes PRMT1 methylation of both histone H4 and histone H2A. We found equimolar or a 10-fold excess of PRMT2 to PRMT1 can improve the catalytic efficiency of PRMT1 towards individual histone substrates H2A, H3, and H4. We further evaluated the effects of PRMT2 towards PRMT1 on unmodified histone octamers and mononucleosomes and found marginal PRMT1 activity improvements in histone octamers but significantly greater methylation of mononucleosomes in the presence of 10-fold excess of PRMT2. This work reveals the ability of PRMT2 to serve a noncatalytic role through its SH3 domain in driving site-specific histone methylation marks.

UTERINE DOSE CONVERSION COEFFICIENTS FOR EXTERNAL PHOTONS FOR THE TAIWANESE PREGNANT WOMEN.

The Oak Ridge National Laboratory (ORNL) phantoms based on data of Caucasians have been widely used for fetal dosimetry. However, there are differences in body size during pregnancy among Taiwanese and Caucasians. In this study, the uterine dose conversion coefficients (DCCs) of Taiwanese pregnant women were evaluated to facilitate the use of it to estimate the possible uterine dose (usually regarded as fetal dose) of pregnant Taiwanese women during radiation practice or medical exposures. The uterine DCCs in this study were calculated based on the established Taiwanese pregnancy voxel phantoms, and were compared with the uterine DCCs of the International Commission on Radiological Protection. The applicability of evaluating uterine DCCs with different phantoms was also discussed. Results showed that if the ORNL phantoms are used to evaluate the uterine dose of Taiwanese pregnant women, the uterine dose may be underestimated. This study provides the uterine DCCs assessed with the Taiwanese pregnancy phantoms for future dose assessment of Taiwanese.

Tape Versus Suture in Arthroscopic Rotator Cuff Repair: Biomechanical Analysis and Assessment of Failure Rates at 6 Months.

BACKGROUND: Rotator cuff retears after surgical repair are associated with poorer subjective and objectives clinical outcomes than intact repairs. PURPOSE: The aims of this study were to (1) examine the biomechanical differences between rotator cuff repair using No. 2 suture and tape in an ovine model and (2) compare early clinical outcomes between patients who had rotator cuff repair with tape and patients who had repair with No. 2 suture. STUDY DESIGN: Controlled laboratory study and cohort study; Level of evidence, 3. METHODS: Biomechanical testing of footprint contact pressure and load to failure were conducted with 16 ovine shoulders using a tension band repair technique with 2 different types of sutures (No. 2 suture [FiberWire; Arthrex] and tape [FiberTape; Arthrex]) with the same knotless anchor system. A retrospective study of 150 consecutive patients (tape, n = 50; suture, n = 100) who underwent arthroscopic rotator cuff repair by a single surgeon with tear size larger than 1.5 × 1 cm was conducted. Ultrasound was used to evaluate the repair integrity at 6 months postsurgery. RESULTS: Rotator cuff repair using tape had greater footprint contact pressure (mean ± standard error of the mean, 0.33 ± 0.03 vs 0.11 ± 0.3 MPa; P < .0001) compared with repair using No. 2 sutures at 0° abduction with a 30-N load applied across the repaired tendon. The ultimate failure load of the tape repair was greater than that for suture repair (217 ± 28 vs 144 ± 14 N; P < .05). The retear rate was similar between the tape (16%; 8/50) and suture groups (17%; 17/100). CONCLUSION: Rotator cuff repair with the wider tape compared with No. 2 suture did not affect the retear rate at 6 months postsurgery, despite having superior biomechanical properties.

Enzymatic saccharification of cassava residues and glucose inhibitory kinetics on ß-glucosidase from Hypocrea orientalis.

Cassava residues are byproducts of the starch industry containing abundant cellulose for bioproduction of green fuel. To obtain maximum sugar yields from cassava residues, the optimal conditions for hydrolyzing the residues were determined using cellulase prepared from a novel Hypocrea orientalis strain. The optimal pH value and optimal temperature for the cellulase hydrolysis were 5.0 and 50 °C, respectively. The concentration of NaOH was determined to be 1% for pretreatment of cassava residues to gain enough soluble sugars suitably. The yield of released sugars was 10 mg/mL in the optimal conditions after 24 h of reaction, which was similar to that of bagasse and wheat grass. Inhibition kinetics of H. orientalis ß-glucosidase (BG) by glucose was first studied using the progress-of-substrate-reaction method as described by Tsou (Tsou, C. L. Adv. Enzymol. Related Areas Mol. Biol. 1988, 61, 381-436), and the microscopic inhibition rate constants of glucose were determined. The results showed that glucose could inhibit BG reversibly and competitively. The rate constants of forward (k(+0)) and reverse (k(-0)) reaction were measured to be 4.88 × 10(-4) (mM·s)(-1) and 2.7 × 10(-4) s(-1), respectively. Meanwhile, the inhibition was more significant than that of L-glucose, D-mannose, D-galactose, D-aminoglucose, acetyl-D-glucose, and D-fructose. This work reveals how to increase sugar yields and reduce product inhibition during enzymatic saccharification of cellulose.