[Discussion on internal fixation of Hoffa fractures].

Hoffa fracture is an unstable intra-articular fracture with significant redisplacement tendency. It is easy to be missed diagnosis when accompanied by distal intercondylar or supracondylar fracture of femur. CT scan is the gold standard for the diagnosis of Hoffa fracture. The treatment principles are anatomic reduction of the articular surface, reliable internal fixation, and early functional activity. At present, the main treatment is arthroscopic screw fixation. During screw fixation, the tail cap of screw should be buried, resulting in non-healing iatrogenic injury of articular cartilage. In the early postoperative functional activity of knee joint, fracture block was repeatedly subjected to backward and upward shear force under the action of the tibial plateau, which is the main reason for the failure of internal fixation. Plate assisted screw fixation could increase local mechanical stability, but it still cannot avoid the defects of iatrogenic cartilage injury. At the same time, plate molding is required during the operation due to the absence of special anatomical plates, resulting in increased surgical trauma and time-consuming surgery. The ideal fixation method for Hoffa fracture should include:(1) Avoid iatrogenic injury of articular surface cartilage. (2) With the rear anti-shear barrier plate function.(3) The internal fixator is closer to the load interface, so as to obtain greater load and better fixed strength.

Prophylactic Epidural Blood Patch or Prophylactic Epidural Infusion of Hydroxyethyl Starch in Preventing Post-Dural Puncture Headache - A Retrospective Study.

BACKGROUND: Post-dural puncture headache (PDPH) is particularly likely to happen in patients under obstetric care due to an unintentional dural puncture (UDP). There is as yet no ideal strategy for preventing UDP-induced PDPH. OBJECTIVES: The primary objective of this study was to assess whether a prophylactic epidural blood patch (EBP) or prophylactic epidural infusion of hydroxyethyl starch (HES) is effective in preventing PDPH for parturients with UDP compared with conservative treatments. STUDY DESIGN: Retrospective analysis from a single center's inpatient data. SETTING: Department of Anesthesiology at a single center. METHODS: A retrospective study was conducted of a single center's inpatient data from January 2017 through March 2020. The study included parturients with UDP during neuraxial anesthesia. The interventions of UDP included conservative treatment, prophylactic EBP, and prophylactic epidural infusion of HES. The incidence of PDPH, the use of intravenous aminophylline, therapeutic EBP, symptom onset, duration of headache, and duration of hospital stay were compared. RESULTS: A total of 85 patients were analyzed. The incidences of PDPH were 84%, 52.6% and 54.5% with conservative, prophylactic EBP, and prophylactic epidural HES treatments, respectively. Compared with the conservative treatment, prophylactic EBP and prophylactic epidural HES treatment significantly reduced the incidence of PDPH (P < 0.05). No significant difference was found between the prophylactic EBP and prophylactic epidural HES groups. Compared with the conservative treatment group, therapeutic EBP was significantly less used in the prophylactic EBP and prophylactic epidural HES groups (P < 0.05). Prophylactic EBP shortened the length of hospital stay of parturients with UDP (P < 0.05) while prophylactic epidural HES showed no statistical difference compared with conservative treatment. No severe complications, such as central nervous system and puncture site infection or nerve injury, were found in those patients. LIMITATIONS: Retrospective nature and single center data with a relatively small sample size. CONCLUSIONS: Prophylactic management with EBP and epidural infusion of HES has an effect in preventing the occurrence of PDPH; prophylactic EBP significantly shortened hospital stay length in parturients with UDP. KEY WORDS: Unintentional dural puncture, epidural blood patch, hydroxyethyl starch, post-dural puncture headache, parturient.

MINDY1 Is a Downstream Target of the Polyamines and Promotes Embryonic Stem Cell Self-Renewal.

Embryonic stem cells have the ability to self-renew or differentiate and these processes are under tight control. We previously reported that the polyamine regulator AMD1 is critical for embryonic stem cell self-renewal. The polyamines putrescine, spermidine, and spermine are essential organic cations that play a role in a wide array of cellular processes. Here, we explore the essential role of the polyamines in the promotion of self-renewal and identify a new stem cell regulator that acts downstream of the polyamines: MINDY1. MINDY1 protein levels are high in embryonic stem cells (ESCs) and are dependent on high polyamine levels. Overexpression of MINDY1 can promote ESC self-renewal in the absence of the usually essential cytokine Leukemia Inhibitory Factor (LIF). MINDY1 protein is prenylated and this modification is required for its ability to promote self-renewal. We go on to show that Mindy1 RNA is targeted for repression by mir-710 during Neural Precursor cell differentiation. Taken together, these data demonstrate that high polyamine levels are required for ESC self-renewal and that they function, in part, through promotion of high MINDY1 levels. Stem Cells 2018;36:1170-1178.

Autophagy Promotes Peripheral Nerve Regeneration and Motor Recovery Following Sciatic Nerve Crush Injury in Rats.

Autophagy maintains cellular homeostasis by stimulating the lysosomal degradation of cytoplasmic structures, including damaged organelles and dysfunctional proteins. The role of autophagy in the renewal and regeneration of injured peripheral nerves remains poorly understood. The current study investigated the role of autophagy in peripheral nerve regeneration and motor function recovery following sciatic nerve crush injury in rats by stimulating or suppressing autophagy and detecting the presence of autophagosomes and LC3-II expression by electron microscopy and Western blotting, respectively. Neurobehavioral function was tested by CatWalk gait analysis 1, 2, 3, and 6 weeks after injury, and the expression of neurofilament (NF)-200 and myelin basic protein (MBP) at the injury site was examined by immunocytochemistry. Apoptosis at the lesion site was determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Treatment of injured rats with the autophagy inducer rapamycin increased the number of autophagosomes and LC3-II expression while reducing the number of apoptotic cells at the lesion; this was associated with an upregulation of MBP and NF-200 expression and increased motor function recovery as compared to sham-operated rats and those that were subjected to crush injury but untreated. The opposite effects were observed in rats treated with the autophagy inhibitor 3-methyladenine. These data indicate that the modulation of autophagy in peripheral nerve injury could be an effective pharmacological approach to promote nerve regeneration and reestablish motor function.

Embryonic Stem Cells Exhibit mRNA Isoform Specific Translational Regulation.

The presence of multiple variants for many mRNAs is a major contributor to protein diversity. The processing of these variants is tightly controlled in a cell-type specific manner and has a significant impact on gene expression control. Here we investigate the differential translation rates of individual mRNA variants in embryonic stem cells (ESCs) and in ESC derived Neural Precursor Cells (NPCs) using polysome profiling coupled to RNA sequencing. We show that there are a significant number of detectable mRNA variants in ESCs and NPCs and that many of them show variant specific translation rates. This is correlated with differences in the UTRs of the variants with the 5'UTR playing a predominant role. We suggest that mRNA variants that contain alternate UTRs are under different post-transcriptional controls. This is likely due to the presence or absence of miRNA and protein binding sites that regulate translation rate. This highlights the importance of addressing translation rate when using mRNA levels as a read out of protein abundance. Additional analysis shows that many annotated non-coding mRNAs are present on the polysome fractions in ESCs and NPCs. We believe that the use of polysome fractionation coupled to RNA sequencing is a useful method for analysis of the translation state of many different RNAs in the cell.

Divergent LIN28-mRNA associations result in translational suppression upon the initiation of differentiation.

LIN28 function is fundamental to the activity and behavior of human embryonic stem cells (hESCs) and induced pluripotent stem cells. Its main roles in these cell types are the regulation of translational efficiency and let-7 miRNA maturation. However, LIN28-associated mRNA cargo shifting and resultant regulation of translational efficiency upon the initiation of differentiation remain unknown. An RNA-immunoprecipitation and microarray analysis protocol, eRIP, that has high specificity and sensitivity was developed to test endogenous LIN28-associated mRNA cargo shifting. A combined eRIP and polysome analysis of early stage differentiation of hESCs with two distinct differentiation cues revealed close similarities between the dynamics of LIN28 association and translational modulation of genes involved in the Wnt signaling, cell cycle, RNA metabolism and proteasomal pathways. Our data demonstrate that change in translational efficiency is a major contributor to early stages of differentiation of hESCs, in which LIN28 plays a central role. This implies that eRIP analysis of LIN28-associated RNA cargoes may be used for rapid functional quality control of pluripotent stem cells under manufacture for therapeutic applications.

Lamin B1 fluctuations have differential effects on cellular proliferation and senescence.

The nuclear lamina consists of A- and B-type lamins. Mutations in LMNA cause many human diseases, including progeria, a premature aging syndrome, whereas LMNB1 duplication causes adult-onset autosomal dominant leukodystrophy (ADLD). LMNB1 is reduced in cells from progeria patients, but the significance of this reduction is unclear. In this paper, we show that LMNB1 protein levels decline in senescent human dermal fibroblasts and keratinocytes, mediated by reduced transcription and inhibition of LMNB1 messenger ribonucleic acid (RNA) translation by miRNA-23a. This reduction is also observed in chronologically aged human skin tissue. To determine whether altered LMNB1 levels cause senescence, we either increased or reduced LMNB1. Both LMNB1 depletion and overexpression inhibited proliferation, but only LMNB1 overexpression induced senescence, which was prevented by telomerase expression or inactivation of p53. This phenotype was exacerbated by a simultaneous reduction of LMNA/C. Our results demonstrate that altering LMNB1 levels inhibits proliferation and are relevant to understanding the molecular pathology of ADLD.