Outcome of Open Repair of Thoracoabdominal Aortic Aneurysm in Takayasu Arteritis: A Retrospective Analysis.

BACKGROUND: Takayasu Arteritis (TA) is an immune mediated arteritis causing inflammation of the aorta and its branches, which can result in aortic aneurysms. Our aim is to describe the outcome of surgical management in these patients who presented with Thoracoabdominal aortic aneurysm (TAAA). METHODS: Between 2003 and 2023, 40 TA patients with TAAA underwent operative repair. RESULTS: There were 24 females and 16 males, in the age group of 19-53 years, with hypertension in 20 patients. Raised Erythrocyte sedimentation Rate was present in 13 patients. According to Crawford classification, there were 2 patients with type I, 2 with type II, 17 with type III, 12 patients with type IV and 7 with type V aneurysm. Multiple steno-occlusive lesions of aortic branches were present in 21 patients, with majority affecting the renal artery. Femoral Artery Femoral Vein Partial cardiopulmonary bypass was used for types I, II, III and V. Separate bypass to visceral branches was done in eight patients, of whom five had multiple bypasses and three patients only had renal bypass. Twelve patients underwent reimplantation of branches, out of which nine had multiple vessel reimplantation. Four patients underwent staged repair of the aneurysm, which included visceral debranching in the first day, followed by repair of the aneurysm in the next day. In the immediate postoperative period, ten patients developed acute kidney injury and two required dialysis. Other morbidities included acute respiratory distress syndrome (ARDS), spinal cord dysfunction, bleeding, and wound complications. Three patients expired in the immediate postoperative period. Mean duration of intensive care unit stay was 4.1 days and hospital stay was 12.7 days. Comparison of disease activity with morbidity and mortality was statistically insignificant. Patients were on follow-up for a range of 6 months to 14 years and median follow-up of 25 months. Over this time period four patients expired and four developed anastomotic pseudoaneurysm requiring intervention. On comparing the disease activity at the time of surgery with the long-term arteritis related complications that required intervention, the P value was 0.653 and hence statistically not significant. The 10-year survival rate is 84.4%. CONCLUSIONS: Surgical repair has good and satisfactory outcome, with low early and late mortality rates. Progression of disease can occur at any stage of the disease, hence indicating the need for long term follow-up and frequent imaging.

Crucial roles of the Arp2/3 complex during mammalian corticogenesis.

The polarity and organization of radial glial cells (RGCs), which serve as both stem cells and scaffolds for neuronal migration, are crucial for cortical development. However, the cytoskeletal mechanisms that drive radial glial outgrowth and maintain RGC polarity remain poorly understood. Here, we show that the Arp2/3 complex - the unique actin nucleator that produces branched actin networks - plays essential roles in RGC polarity and morphogenesis. Disruption of the Arp2/3 complex in murine RGCs retards process outgrowth toward the basal surface and impairs apical polarity and adherens junctions. Whereas the former is correlated with an abnormal actin-based leading edge, the latter is consistent with blockage in membrane trafficking. These defects result in altered cell fate, disrupted cortical lamination and abnormal angiogenesis. In addition, we present evidence that the Arp2/3 complex is a cell-autonomous regulator of neuronal migration. Our data suggest that Arp2/3-mediated actin assembly might be particularly important for neuronal cell motility in a soft or poorly adhesive matrix environment.

Enhancing mitochondrial proteolysis alleviates alpha-synuclein-mediated cellular toxicity.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by mitochondrial dysfunction and accumulation of alpha-synuclein (α-Syn)-containing protein aggregates known as Lewy bodies (LB). Here, we investigated the entry of α-Syn into mitochondria to cause mitochondrial dysfunction and loss of cellular fitness in vivo. We show that α-Syn expressed in yeast and human cells is constitutively imported into mitochondria. In a transgenic mouse model, the level of endogenous α-Syn accumulation in mitochondria of dopaminergic neurons and microglia increases with age. The imported α-Syn is degraded by conserved mitochondrial proteases, most notably NLN and PITRM1 (Prd1 and Cym1 in yeast, respectively). α-Syn in the mitochondrial matrix that is not degraded interacts with respiratory chain complexes, leading to loss of mitochondrial DNA (mtDNA), mitochondrial membrane potential and cellular fitness decline. Importantly, enhancing mitochondrial proteolysis by increasing levels of specific proteases alleviated these defects in yeast, human cells, and a PD model of mouse primary neurons. Together, our results provide a direct link between α-synuclein-mediated cellular toxicity and its import into mitochondria and reveal potential therapeutic targets for the treatment of α-synucleinopathies.

Fibrocystin/Polyductin releases a C-terminal fragment that translocates into mitochondria and suppresses cystogenesis.

Fibrocystin/Polyductin (FPC), encoded by PKHD1, is associated with autosomal recessive polycystic kidney disease (ARPKD), yet its precise role in cystogenesis remains unclear. Here we show that FPC undergoes complex proteolytic processing in developing kidneys, generating three soluble C-terminal fragments (ICDs). Notably, ICD15, contains a novel mitochondrial targeting sequence at its N-terminus, facilitating its translocation into mitochondria. This enhances mitochondrial respiration in renal epithelial cells, partially restoring impaired mitochondrial function caused by FPC loss. FPC inactivation leads to abnormal ultrastructural morphology of mitochondria in kidney tubules without cyst formation. Moreover, FPC inactivation significantly exacerbates renal cystogenesis and triggers severe pancreatic cystogenesis in a Pkd1 mouse mutant Pkd1V/V in which cleavage of Pkd1-encoded Polycystin-1 at the GPCR Proteolysis Site is blocked. Deleting ICD15 enhances renal cystogenesis without inducing pancreatic cysts in Pkd1V/V mice. These findings reveal a direct link between FPC and a mitochondrial pathway through ICD15 cleavage, crucial for cystogenesis mechanisms.

Maintenance of the diacylglycerol level in the Golgi apparatus by the Nir2 protein is critical for Golgi secretory function.

The level of diacylglycerol (DAG) in the Golgi apparatus is crucial for protein transport to the plasma membrane. Studies in budding yeast indicate that Sec14p, a phosphatidylinositol (PI)-transfer protein, is involved in regulating DAG homeostasis in the Golgi complex. Here, we show that Nir2, a peripheral Golgi protein containing a PI-transfer domain, is essential for maintaining the structural and functional integrity of the Golgi apparatus in mammalian cells. Depletion of Nir2 by RNAi leads to substantial inhibition of protein transport from the trans-Golgi network to the plasma membrane, and causes a reduction in the DAG level in the Golgi apparatus. Remarkably, inactivation of cytidine [corrected] 5'-diphosphate (CDP)-choline pathway for phosphatidylcholine biosynthesis restores both effects. These results indicate that Nir2 is involved in maintaining a critical DAG pool in the Golgi apparatus by regulating its consumption via the CDP-choline pathway, demonstrating the interface between secretion from the Golgi and lipid homeostasis.

Conventional Carotid Endarterectomy with Shunt versus Eversion Carotid Endarterectomy without Shunt does the Technique Influence the Outcome in Symptomatic Critical Carotid Stenosis.

INTRODUCTION: Carotid endarterectomy (CEA) is a surgical procedure done to prevent future embolic stroke in patients with internal carotid artery (ICA) stenosis. Conventional CEA (c-CEA) and eversion CEA (e-CEA) are two surgical techniques used for the above. As carotid shunt is rarely used in e-CEA, a certain amount of cerebral ischemia occurs in patients who were already having carotid stenosis. In this study, we have evaluated the outcome of two surgical techniques in severe carotid stenosis and impact of carotid shunting on the postoperative outcome. MATERIALS AND METHODS: In this single-center prospective nonrandomized trial, a total of 62 patients who underwent CEA (c-CEA, n = 31; e-CEA, n = 31) for symptomatic ipsilateral ICA stenosis ≥50% between January 2018 and December 2019 were included. RESULTS: A total of 62 patients who underwent CEA (c-CEA, n = 31; e-CEA, n = 31) for symptomatic ipsilateral ICA stenosis ≥50% were included in the study. There was no major stroke or stroke related death in both the study groups. One patient in e-CEA had carotid occlusion and minor stroke. There was no statistically significant difference in minor stroke (e-CEA [3.2%], c-CEA [3.2%], P = 1), transient ischemic attack (e-CEA [3.2%], c-CEA n = 0, P = 0.3), postoperative MI (e-CEA (3.2%), c-CEA (3.2%), P = 1), hematoma (e-CEA [3.2%], c-CEA n = 0, P = 0.3), and re-exploration (e-CEA [3.2%], c-CEA n = 0, P = 0.3). The incidence of cranial nerve (CN) dysfunction was significantly higher in eversion group as compared to c-CEA (e-CEA n = 6 [19.4%], c-CEA n = 1, [3.2%] P = 0.045). CONCLUSION: Our study showed that the early outcomes of both c-CEA and e-CEA techniques are comparable. The routine insertion of carotid shunt even though decreases the cerebral ischemic time, it does not offer any additional advantage of decreasing perioperative stroke. The choice of the CEA technique depends on the experience and familiarity of the individual surgeon as both the techniques have their own advantages and disadvantages.

Dopamine receptor antagonists as potential therapeutic agents for ADPKD.

Autosomal dominant polycystic kidney disease (ADPKD) is caused mostly by mutations in polycystin-1 or polycystin-2. Fluid flow leads to polycystin-dependent calcium influx and nuclear export of histone deacetylase 5 (HDAC5), which facilitates the maintenance of renal epithelial architecture by de-repression of MEF2C target genes. Here, we screened a small-molecule library to find drugs that promotes nuclear export of HDAC5. We found that dopamine receptor antagonists, domperidone and loxapine succinate, stimulate export of HDAC5, even in Pkd1-/-cells. Domperidone targets Drd3 receptor to modulate the phosphorylation of HDAC5. Domperidone treatment increases HDAC5 phosphorylation likely by reducing protein phosphatase 2A (PP2A) activity, thus shifting the equilibrium towards HDAC5-P and export from the nucleus. Treating Pkd1-/-mice with domperidone showed significantly reduced cystic growth and cell proliferation. Further, treated mice displayed a reduction in glomerular cyst and increased body weight and activity. These results suggest that HDAC5 nucleocytoplasmic shuttling may be modulated to impede disease progression in ADPKD and uncovers an unexpected role for a class of dopamine receptors in renal epithelial morphogenesis.

Differential regulation of endoplasmic reticulum structure through VAP-Nir protein interaction.

The endoplasmic reticulum (ER) exhibits a characteristic tubular structure that is dynamically rearranged in response to specific physiological demands. However, the mechanisms by which the ER maintains its characteristic structure are largely unknown. Here we show that the integral ER-membrane protein VAP-B causes a striking rearrangement of the ER through interaction with the Nir2 and Nir3 proteins. We provide evidence that Nir (Nir1, Nir2, and Nir3)-VAP-B interactions are mediated through the conserved FFAT (two phenylalanines (FF) in acidic tract) motif present in Nir proteins. However, each interaction affects the structural integrity of the ER differently. Whereas the Nir2-VAP-B interaction induces the formation of stacked ER membrane arrays, the Nir3-VAP-B interaction leads to a gross remodeling of the ER and the bundling of thick microtubules along the altered ER membranes. In contrast, the Nir1-VAP-B interaction has no apparent effect on ER structure. We also show that the Nir2-VAP-B interaction attenuates protein export from the ER. These results demonstrate new mechanisms for the regulation of ER structure, all of which are mediated through interaction with an identical integral ER-membrane protein.

Mitotic phosphorylation of the peripheral Golgi protein Nir2 by Cdk1 provides a docking mechanism for Plk1 and affects cytokinesis completion.

The rearrangement of the Golgi apparatus during mitosis is regulated by several protein kinases, including Cdk1 and Plk1. Several peripheral Golgi proteins that dissociate from the Golgi during mitosis are implicated in regulation of cytokinesis or chromosome segregation, thereby coordinating mitotic and cytokinetic events to Golgi rearrangement. Here we show that, at the onset of mitosis, Cdk1 phosphorylates the peripheral Golgi protein Nir2 at multiple sites; of these, S382 is the most prominent. Phosphorylation of Nir2 by Cdk1 facilitates its dissociation from the Golgi apparatus, and phospho-Nir2(pS382) is localized in the cleavage furrow and midbody during cytokinesis. Mitotic phosphorylation of Nir2 is required for docking of the phospho-Ser/Thr binding module, the Polo box domain of Plk1, and overexpression of a Nir2 mutant, which fails to interact with Plk1, affects the completion of cytokinesis. These results demonstrate a mechanism for coordinating mitotic and cytokinetic events with Golgi rearrangement during cell division.