Comparison of the Utilization of Tranexamic Acid and Tourniquet Use in Total Knee Arthroplasty: A Retrospective Case Series.

INTRODUCTION: Total knee arthroplasty (TKA) carries a high risk for significant blood loss due to bone cuts and extensive soft tissue involvement in the knee region. The use of tranexamic acid (TXA) or a tourniquet are two methods commonly employed to prevent significant blood loss and avoid the need for blood transfusion. TXA has been shown to reduce both intraoperative and postoperative bleeding as well as the probability that a patient will require a blood transfusion. The purpose of this study is to compare the efficacy of TXA and tourniquet use, both alone and in combination, in reducing blood loss during TKA. METHODS: Data for this retrospective cohort study were obtained by searching records of patients who underwent TKA at a tertiary care center from January 2019 to October 2020. Data from 526 subjects were available. A chart review was conducted to determine if the patient received TXA only, tourniquet only, or both TXA and tourniquet during the TKA procedure. Primary outcomes for this study including procedure length in minutes, estimated blood loss in cubic centimeters, and total infusion pressor (phenylephrine) administered intraoperatively in milligrams were recorded for the study. Data were summarized using means and standard errors. Statistical methods used for analysis include one-way ANOVA, probability plots, the Shapiro-Wilk test for normality, the Kruskal-Wallis test, and Tukey's test. RESULTS: Data were available for 526 subjects. 122 subjects received tourniquet only (Tourniquet group), 104 received intravenous (IV) TXA only, 264 received both tourniquet and IV TXA (Tourniquet + TXA), and 36 received neither tourniquet nor TXA (None). The groups did not significantly differ in procedure length (p = 0.140) or infusion pressor total (p > 0.20). The groups did significantly differ in estimated blood loss (p < 0.001). Subjects who did not receive either TXA or tourniquet had significantly more blood loss than the Tourniquet and Tourniquet + TXA groups. Similarly, the TXA group had significantly more blood loss than both the Tourniquet and Tourniquet + TXA groups. CONCLUSION: This study supports the conclusion that the use of a tourniquet is superior to the use of TXA in reducing intraoperative blood loss during TKA. All groups that underwent TKA using a tourniquet, either alone or in combination with TXA, exhibited significantly lower levels of blood loss compared to the control (no intervention) group.

Leukocytes mediate disease pathogenesis in the Ndufs4(KO) mouse model of Leigh syndrome.

Symmetric, progressive, necrotizing lesions in the brainstem are a defining feature of Leigh syndrome (LS). A mechanistic understanding of the pathogenesis of these lesions has been elusive. Here, we report that leukocyte proliferation is causally involved in the pathogenesis of LS. Depleting leukocytes with a colony-stimulating factor 1 receptor inhibitor disrupted disease progression, including suppression of CNS lesion formation and a substantial extension of survival. Leukocyte depletion rescued diverse symptoms, including seizures, respiratory center function, hyperlactemia, and neurologic sequelae. These data reveal a mechanistic explanation for the beneficial effects of mTOR inhibition. More importantly, these findings dramatically alter our understanding of the pathogenesis of LS, demonstrating that immune involvement is causal in disease. This work has important implications for the mechanisms of mitochondrial disease and may lead to novel therapeutic strategies.

A systematic review of biomarkers associated with maternal infection in pregnant and postpartum women.

BACKGROUND: Serum biomarkers are commonly used to support the diagnosis of infection in non-pregnant patients whose clinical presentation suggests infection. The utility of serum biomarkers for infection in pregnant and postpartum women is uncertain. SEARCH STRATEGY: PubMed, CINAHL, EMBASE, ClinicalTrials.gov, Cochrane Library, CINAHL, and SCOPUS were searched from inception to February 2020. SELECTION CRITERIA: Full-text manuscripts in English were included if they reported the measurement of maternal serum biomarkers-and included a control group-to identify infection in pregnant and postpartum women. DATA COLLECTION AND ANALYSIS: two authors independently screened manuscripts, extracted data, and assessed methodologic quality. MAIN RESULTS: Interleukin-6 (IL-6), C-reactive protein, procalcitonin, insulin-like growth factor binding protein 1, tumor necrosis factor-α, calgranulin B, neopterin, and interferon-γ inducible protein 10 reliably indicated infection. Intercellular adhesion molecule 1, monocyte chemotactic and activating factor, soluble IL-6 receptor, and IL-8 were not useful markers in pregnant and postpartum women. CONCLUSIONS: Findings suggest that certain biomarkers have diagnostic value when maternal infection is suspected, but also confirms limitations in this population.

Retrospective Case Series Comparing the Efficacy of Thoracic Epidural With Continuous Paravertebral and Erector Spinae Plane Blocks for Postoperative Analgesia After Thoracic Surgery.

Perioperative pain management for thoracic surgery plays a vital role in recovery and improved outcomes. In this retrospective study we compare three different regional anesthesia techniques utilized at one institute to provide postoperative analgesia for thoracic surgery. Continuous thoracic epidural analgesia (TEA), thoracic paravertebral block (PVB) and erector spinae plane (ESP) block are compared for postoperative pain management, opioid requirements, postoperative nausea and vomiting (PONV), respiratory events and length of stay. In this study, pairwise comparisons were also performed among the regional techniques with respect to mentioned outcomes.

Mechanisms underlying neonate-specific metabolic effects of volatile anesthetics.

Volatile anesthetics (VAs) are widely used in medicine, but the mechanisms underlying their effects remain ill-defined. Though routine anesthesia is safe in healthy individuals, instances of sensitivity are well documented, and there has been significant concern regarding the impact of VAs on neonatal brain development. Evidence indicates that VAs have multiple targets, with anesthetic and non-anesthetic effects mediated by neuroreceptors, ion channels, and the mitochondrial electron transport chain. Here, we characterize an unexpected metabolic effect of VAs in neonatal mice. Neonatal blood ß-hydroxybutarate (ß-HB) is rapidly depleted by VAs at concentrations well below those necessary for anesthesia. ß-HB in adults, including animals in dietary ketosis, is unaffected. Depletion of ß-HB is mediated by citrate accumulation, malonyl-CoA production by acetyl-CoA carboxylase, and inhibition of fatty acid oxidation. Adults show similar significant changes to citrate and malonyl-CoA, but are insensitive to malonyl-CoA, displaying reduced metabolic flexibility compared to younger animals.

Microtubules are necessary for proper Reticulon localization during mitosis.

During mitosis, the structure of the Endoplasmic Reticulum (ER) displays a dramatic reorganization and remodeling, however, the mechanism driving these changes is poorly understood. Hairpin-containing ER transmembrane proteins that stabilize ER tubules have been identified as possible factors to promote these drastic changes in ER morphology. Recently, the Reticulon and REEP family of ER shaping proteins have been shown to heavily influence ER morphology by driving the formation of ER tubules, which are known for their close proximity with microtubules. Here, we examine the role of microtubules and other cytoskeletal factors in the dynamics of a Drosophila Reticulon, Reticulon-like 1 (Rtnl1), localization to spindle poles during mitosis in the early embryo. At prometaphase, Rtnl1 is enriched to spindle poles just prior to the ER retention motif KDEL, suggesting a possible recruitment role for Rtnl1 in the bulk localization of ER to spindle poles. Using image analysis-based methods and precise temporal injections of cytoskeletal inhibitors in the early syncytial Drosophila embryo, we show that microtubules are necessary for proper Rtnl1 localization to spindles during mitosis. Lastly, we show that astral microtubules, not microfilaments, are necessary for proper Rtnl1 localization to spindle poles, and is largely independent of the minus-end directed motor protein dynein. This work highlights the role of the microtubule cytoskeleton in Rtnl1 localization to spindles during mitosis and sheds light on a pathway towards inheritance of this major organelle.

UbiA prenyltransferase domain-containing protein-1 modulates HMG-CoA reductase degradation to coordinate synthesis of sterol and nonsterol isoprenoids.

UBIAD1 (UbiA prenyltransferase domain-containing protein-1) utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize vitamin K2 We previously reported that sterols stimulate binding of UBIAD1 to endoplasmic reticulum (ER)-localized 3-hydroxy-3-methylglutaryl (HMG) CoA reductase. UBIAD1 binding inhibits sterol-accelerated, ER-associated degradation (ERAD) of reductase, one of several mechanisms for feedback control of this rate-limiting enzyme in the branched pathway that produces cholesterol and nonsterol isoprenoids such as GGpp. Accumulation of GGpp in ER membranes triggers release of UBIAD1 from reductase, permitting its maximal ERAD and ER-to-Golgi transport of UBIAD1. Mutant UBIAD1 variants associated with Schnyder corneal dystrophy (SCD), a human disorder characterized by corneal accumulation of cholesterol, resist GGpp-induced release from reductase and remain sequestered in the ER to block reductase ERAD. Using lines of genetically manipulated cells, we now examine consequences of UBIAD1 deficiency and SCD-associated UBIAD1 on reductase ERAD and cholesterol synthesis. Our results indicated that reductase becomes destabilized in the absence of UBIAD1, resulting in reduced cholesterol synthesis and intracellular accumulation. In contrast, an SCD-associated UBIAD1 variant inhibited reductase ERAD, thereby stabilizing the enzyme and contributing to enhanced synthesis and intracellular accumulation of cholesterol. Finally, we present evidence that GGpp-regulated, ER-to-Golgi transport enables UBIAD1 to modulate reductase ERAD such that synthesis of nonsterol isoprenoids is maintained in sterol-replete cells. These findings further establish UBIAD1 as a central player in the reductase ERAD pathway and regulation of isoprenoid synthesis. They also indicate that UBIAD1-mediated inhibition of reductase ERAD underlies cholesterol accumulation associated with SCD.

Underlying mechanisms for sterol-induced ubiquitination and ER-associated degradation of HMG CoA reductase.

Accelerated ubiquitination and subsequent endoplasmic reticulum (ER)-associated degradation (ERAD) constitute one of several mechanisms for feedback control of HMG CoA reductase, the rate-limiting enzyme in synthesis of cholesterol and nonsterol isoprenoids. This ERAD is initiated by the accumulation of certain sterols in ER membranes, which trigger binding of reductase to ER membrane proteins called Insigs. Insig-associated ubiquitin ligases facilitate ubiquitination of reductase, marking the enzyme for extraction across the ER membrane through a reaction that is augmented by nonsterol isoprenoids. Once extracted, ubiquitinated reductase becomes dislocated into the cytosol for degradation by 26S proteasomes. In this review, we will highlight several advances in the understanding of reductase ERAD, which includes the discovery for a role of the vitamin K2 synthetic enzyme UBIAD1 in the reaction and demonstration that sterol-accelerated ERAD significantly contributes to feedback regulation of reductase and cholesterol metabolism in livers of whole animals.

Dose-dependent effects of mTOR inhibition on weight and mitochondrial disease in mice.

Rapamycin extends lifespan and attenuates age-related pathologies in mice when administered through diet at 14 parts per million (PPM). Recently, we reported that daily intraperitoneal injection of rapamycin at 8 mg/kg attenuates mitochondrial disease symptoms and progression in the Ndufs4 knockout mouse model of Leigh Syndrome. Although rapamycin is a widely used pharmaceutical agent dosage has not been rigorously examined and no dose-response profile has been established. Given these observations we sought to determine if increased doses of oral rapamycin would result in more robust impact on mTOR driven parameters. To test this hypothesis, we compared the effects of dietary rapamycin at doses ranging from 14 to 378 PPM on developmental weight in control and Ndufs4 knockout mice and on health and survival in the Ndufs4 knockout model. High dose rapamycin was well tolerated, dramatically reduced weight gain during development, and overcame gender differences. The highest oral dose, approximately 27-times the dose shown to extend murine lifespan, increased survival in Ndufs4 knockout mice similarly to daily rapamycin injection without observable adverse effects. These findings have broad implications for the effective use of rapamycin in murine studies and for the translational potential of rapamycin in the treatment of mitochondrial disease. This data, further supported by a comparison of available literature, suggests that 14 PPM dietary rapamycin is a sub-optimal dose for targeting mTOR systemically in mice. Our findings suggest that the role of mTOR in mammalian biology may be broadly underestimated when determined through treatment with rapamycin at commonly used doses.

Spatial reorganization of the endoplasmic reticulum during mitosis relies on mitotic kinase cyclin A in the early Drosophila embryo.

Mitotic cyclin-dependent kinase with their cyclin partners (cyclin:Cdks) are the master regulators of cell cycle progression responsible for regulating a host of activities during mitosis. Nuclear mitotic events, including chromosome condensation and segregation have been directly linked to Cdk activity. However, the regulation and timing of cytoplasmic mitotic events by cyclin:Cdks is poorly understood. In order to examine these mitotic cytoplasmic events, we looked at the dramatic changes in the endoplasmic reticulum (ER) during mitosis in the early Drosophila embryo. The dynamic changes of the ER can be arrested in an interphase state by inhibition of either DNA or protein synthesis. Here we show that this block can be alleviated by micro-injection of Cyclin A (CycA) in which defined mitotic ER clusters gathered at the spindle poles. Conversely, micro-injection of Cyclin B (CycB) did not affect spatial reorganization of the ER, suggesting CycA possesses the ability to initiate mitotic ER events in the cytoplasm. Additionally, RNAi-mediated simultaneous inhibition of all 3 mitotic cyclins (A, B and B3) blocked spatial reorganization of the ER. Our results suggest that mitotic ER reorganization events rely on CycA and that control and timing of nuclear and cytoplasmic events during mitosis may be defined by release of CycA from the nucleus as a consequence of breakdown of the nuclear envelope.