Design, synthesis, and biological evaluation of HDAC6 inhibitors targeting L1 loop and serine 531 residue.

Histone deacetylases (HDACs) are a group of enzymes that remove acetyl groups from histones, leading to the silencing of genes. Targeting specific isoforms of HDACs has emerged as a promising approach for cancer therapy, as it can overcome drawbacks associated with pan-HDAC inhibitors. HDAC6 is a unique HDAC isoform that deacetylates non-histone proteins and is primarily located in the cytoplasm. It also has two catalytic domains and a zinc-finger ubiquitin binding domain (Zf-UBD) unlike other HDACs. HDAC6 plays a critical role in various cellular processes, including cell motility, protein degradation, cell proliferation, and transcription. Hence, the deregulation of HDAC6 is associated with various malignancies. In this study, we report the design and synthesis of a series of HDAC6 inhibitors. We evaluated the synthesized compounds by HDAC enzyme assay and identified that compound 8g exhibited an IC50 value of 21 nM and 40-fold selective activity towards HDAC6. We also assessed the effect of compound 8g on various cell lines and determined its ability to increase protein acetylation levels by Western blotting. Furthermore, the increased acetylation of α-tubulin resulted in microtubule polymerization and changes in cell morphology. Our molecular docking study supported these findings by demonstrating that compound 8g binds well to the catalytic pocket via L1 loop of HDAC6 enzyme. Altogether, compound 8g represents a preferential HDAC6 inhibitor that could serve as a lead for the development of more potent and specific inhibitors.

The ultrastructural features of the infundibulum of the green iguana, Iguana iguana.

The purpose of this study is to describe, in detail, the ultrastructure of the infundibulum of the sexually mature and active female green iguana, Iguana iguana. The infundibulum of five iguanas was remarkably distinct from the uterus, and was also clearly demarcated into cranial (expanded v-shaped) and caudal (tubular) divisions. Tissue samples obtained from five portions (three from the cranial division and two from the caudal division) of the infundibulum were processed conventionally for light and electron microscopy. The epithelial lining of the most anterior, middle, and posterior, parts of the cranial division displayed nonciliated cells predominantly, and occasionally ciliated cells. The numerous secretory granules in nonciliated type 1 cell found in the fimbrial aspect of the infundibulum were homogenous and deeply electron-dense, but those in the other two regions were variants of this cell type because they contained variably electron-dense secretory granules. Two main types of nonciliated cells (type 2 and its variant, type 3, as well as type 4) occurred in the epithelial lining of the caudal division of the infundibulum, but they, clearly, showed no dense secretory granules. Whereas the nonciliated type 2 cell and its variant (type 3 cell) contained large glycogen deposits, the type 4 cell lacked these deposits but its apical part contained large lipid-like droplets and, remarkably, blebbed into the duct lumen. The nonciliated cells lining the mucosal tubular glands contained highly electron-dense secretory granules, which were similar to those found in the nonciliated type 1 cell in the epithelial lining of the fimbrial part of the cranial division of the infundibulum.

The Call for Neuroendoscopy Cadaveric Workshops in Lower-Middle Income Countries.

OBJECTIVE: This study aims to assess the impact of the workshops organized during Neuroendocon 23 on the perspective and confidence of neurosurgeons toward endoscopy in a lower-middle income country. METHODS: Neuroendocon 23 had cranial and spinal endoscopy cadaveric workshops with 30 delegates each. A pre and postworkshop survey was disseminated among the delegates, and statistical analysis was performed with SPSS (version 26) using P < 0.05. RESULTS: A total of 24 delegates (40%) consented to participate in the study, with only 1 female respondent (4.17%). After the cranial endoscopy workshop, there was an increase in the level of confidence of delegates in cranial endoscopic approaches (P < 0.001). Similarly, after the spine endoscopy workshop, the respondents had increased confidence in managing spine conditions with the endoscopic approach (P = 0.040), to the extent that they preferred the endoscopic over the microsurgical technique (P < 0.001). All respondents (n = 24, 100%) believed that endoscopy should be promoted in lower-middle income countries and integrated into residency curricula. CONCLUSIONS: Cranial and spinal endoscopy cadaveric workshops could be the first step in stimulating the interest of neurosurgeons in endoscopy.

Exploring new histone deacetylase 6 inhibitors and their effects on reversing the α-tubulin deacetylation and cell morphology changes caused by methamphetamine.

Indazole-based HDAC6 inhibitors with novel zinc-binding modifications were synthesized and evaluated to determine their potential to inhibit HDAC6. The analogs were subjected to a histone deacetylase (HDAC) enzyme assay, which led to identification of compounds 3a and 3b. Both compounds demonstrated higher potency and selectivity as HDAC6 inhibitors with IC50 values of 9.1 nM and 9.0 nM, respectively, and highlighted the importance of the hydroxamic acid moiety for binding to Zn2+ inside the catalytic pocket of HDAC enzymes. In the neuroblastoma SH-SY5Y cell line, both compounds efficiently acetylated α-tubulin but not histone H3 at a low concentration of 0.5 µM. Moreover, compounds 3a and 3b effectively reversed the deacetylation of α-tubulin caused by methamphetamine in the SH-SY5Y cell line, suggesting the potential usefulness of HDAC6 selective inhibition in restoring blood brain barrier integrity by reversing methamphetamine-induced deacetylation.

Dysregulated Genes and Signaling Pathways in the Formation and Rupture of Intracranial Aneurysm.

Intracranial aneurysm (IA) has the potential to rupture. Despite scientific advances, we are still not in a position to screen patients for IA and identify those at risk of rupture. It is critical to comprehend the molecular basis of disease to facilitate the development of novel diagnostic strategies. We used transcriptomics to identify the dysregulated genes and understand their role in the disease biology. In particular, RNA-Seq was performed in tissue samples of controls, unruptured IA, and ruptured IA. Dysregulated genes (DGs) were identified and analyzed to understand the functional aspects of molecules. Subsequently, candidate genes were validated at both transcript and protein level. There were 314 DGs in patients with unruptured IA when compared to control samples. Out of these, SPARC and OSM were validated as candidate molecules in unruptured IA. PI3K-AKT signaling pathway was found to be an important pathway for the formation of IA. Similarly, 301 DGs were identified in the samples of ruptured IA when compared with unruptured IAs. CTSL was found to be a key candidate molecule which along with Hippo signaling pathway may be involved in the rupture of IA. We conclude that activation of PI3K-AKT signaling pathway by OSM along with up-regulation of SPARC is important for the formation of IA. Further, regulation of Hippo pathway through PI3K-AKT signaling results in the down-regulation of YAP1 gene. This along with up-regulation of CTSL leads to further weakening of aneurysm wall and its subsequent rupture.

Exploring antiviral potency of N-1 substituted pyrimidines against HIV-1 and other DNA/RNA viruses: Design, synthesis, characterization, ADMET analysis, docking, molecular dynamics and biological activity.

A novel series of pyrimidine derivatives, bearing modified benzimidazoles at N-1 position, has been designed, synthesized and screened as NNRTIs against HIV and as broad-spectrum antiviral agents. The molecules were screened against different HIV targets using molecular docking experiment. The docking results indicated that the molecules interacted well with the residues Lys101, Tyr181, Tyr188, Trp229, Phe227 and Tyr318 present in NNIBP of HIV-RT protein, formed quite stable complexes and, thus, behaved as probable NNRTIs. Among these compounds, 2b and 4b showed anti-HIV activity with IC50 values as 6.65 µg/mL (SI = 15.50) and 15.82 µg/mL (SI = 14.26), respectively. Similarly, compound 1a showed inhibitory property against coxsackie virus B4 and compound 3b against different viruses. Molecular dynamics simulation results unequivocally demonstrated the higher stability of the complex HIV-RT:2b than the HIV-RT:nevirapine complex. The MM/PBSA-based binding free energy (-) 114.92 kJ/mol of HIV-RT:2b complex in comparison to that of HIV-RT:nevirapine complex (-) 88.33 kJ/mol, further demonstrated the higher binding strength of 2b and thus, established the potential of compound 2b as a lead molecule as an HIV-RT inhibitor.

Reelin Signaling Pathway and Mesial Temporal Lobe Epilepsy: A Causative Link.

Introduction: Mesial temporal lobe epilepsy (MTLE) is the most frequent form of partial epilepsy. Granule cell dispersion, resulting from aberrant neuronal migration in the hippocampus, is pathognomonic of MTLE. Reelin, a secreted neurodevelopmental glycoprotein has a crucial role in controlling the radial migration of neurons. Several animal studies have implicated Reelin in the MTLE pathogenesis Mesial temporal lobe epilepsy (MTLE) is the most frequent form of partial epilepsy. Granule cell dispersion, resulting from aberrant neuronal migration in the hippocampus, is pathognomonic of MTLE. Reelin, a secreted neurodevelopmental glycoprotein has a crucial role in controlling the radial migration of neurons. Several animal studies have implicated Reelin in the MTLE pathogenesis. Methods: The aim of this study was to investigate the Reelin signalling pathway in the MTLE patients. Therefore, we studied each step in the Reelin signalling pathway for the gene and protein expressions, in the hippocampal tissue obtained from patients undergoing surgery for MTLE and compared it with age matched normal autopsy cases. Results: We found statistically significant decrease (P<0.001) in the Reelin mRNA expression in MTLE patients. Among the two reelin receptors, apolipoprotein E receptor 2 (ApoER2) was significantly increased whereas very low density lipoprotein receptor (VLDLR) was decreased among the patients. Disabled 1 (Dab1), the downstream target of reelin, was found to be decreased. Dab1 in turn inhibits Cofilin, which is responsible for cytoskeletal reorganization, thus limiting aberrant neuronal migration. Statistically significant over expression of Cofilin protein was found in the patient group. Matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteases-1 (TIMP-1), both of which are involved in processing of Reelin, were down regulated in 70-85% of cases. Conclusion: The whole pathway was found to be deranged in MTLE. These results indicate that Reelin signalling pathway is disturbed at various points in the MTLE patients and might be involved in the pathogenesis & progression of MTLE. Our results extend the existing information regarding the components of the Reelin pathway and further, establish a link between pathway disturbance and MTLE.

Decompressive Hemi Craniectomy in Malignant Middle Cerebral Artery Infarction: Adding Years of Quality Life or Mere Existence?

Background: In spite of advancements in treatment options for MCA infarct, there is a definite role of decompressive hemicraniectomy. When compared with best medical management, it decreases mortality and improves functional outcome. But does surgery improve quality of life in terms of independence, cognition or it merely leads to increased survival? Objective: Outcome of 43 consecutive patients of MMCAI who underwent DHC was studied. Materials and Methods: Functional outcome was evaluated based on mRS and GOS in addition to survival advantage. The patient's proficiency in performing ADL was evaluated. MMSE and MOCA were performed to evaluate the neuropsychological outcome. Results: In-hospital mortality was 18.6%, and by 3 months, 67.5% of patients survived. During follow-up, nearly 60% of patients showed improvement in functional outcome when evaluated based on mRS and GOS. No patient could reach to the level of independent existence. Only eight patients could perform MMSE and five had good score (>24). All were young and had a right-sided lesion. None of the patients could perform well in MOCA. Conclusion: DHC improves survival and functional outcome. Cognition remains poor in the majority of the patients. These patients, though survive the stroke, remain dependent on care givers.

Asymmetry in cerebral perfusion from circle of Willis arterial variations in normal population.

BACKGROUND: Angiographic and cadaveric studies have evidenced variations in the circle of Willis (CoW). Age-related changes in cerebral hemodynamics may be attributable to vascular variations. OBJECTIVES: The objective is to assess interdependence of completeness of CoW with age using non-invasive MRA and cerebral perfusion using arterial spin labeling (ASL). METHODS: This single-center, prospective study segregated 189 subjects into three groups: ≤5, 5 to 18, and >18 years. Angiographic (complete CoW and vascular asymmetry index) using TOF and contrast-enhanced- (CE-) MRA, and perfusion (perfusion asymmetry index) data using ASL were obtained. RESULTS: One hundred and six (56.08%) subjects showed complete CoW on TOF and 100 (52.91%) on CE-MRA. Anterior and posterior collateral pathways were more prevalent in the younger population. Completeness of CoW decreased with increasing age, group 1 (54/60, 90% TOF; 51/60, 85% CE), group 2 (39/64, 60% TOF; 37/64, 56.92% CE), and group 3 (13/65, 20.31% TOF; 12/65, 18.75% CE); p-value < .0001. A statistically significant decrease in cerebral and cerebellar perfusion with increasing age was seen. Cerebellar to frontal perfusion change was higher in group 1. Fetal posterior cerebral artery (PCA) led to ipsilateral low and contralateral hyperperfusion flow asymmetries between occipital lobes. CONCLUSIONS: This study shows that a complete CoW is commoner in pediatrics than adults and with increasing age, the completeness of CoW decreases paralleled by decrease in cerebral and cerebellar perfusion. There is age-related shift of perfusion from hindbrain to forebrain and the regression of PCoA occurs with increasing age leading to alterations in cerebral perfusion and hemodynamics.

Phosphorylation of ß-catenin at Serine552 correlates with invasion and recurrence of non-functioning pituitary neuroendocrine tumours.

Non-functioning pituitary tumours (NF-PitNETs) are common intracranial benign neoplasms that can exhibit aggressive behaviour by invading neighbouring structures and, in some cases, have multiple recurrences. Despite resulting in severe co-morbidities, no predictive biomarkers of recurrence have been identified for NF-PitNETs. In this study we have used high-throughput mass spectrometry-based analysis to examine the phosphorylation pattern of different subsets of NF-PitNETs. Based on histopathological, radiological, surgical and clinical features, we have grouped NF-PitNETs into non-invasive, invasive, and recurrent disease groups. Tumour recurrence was determined based on regular clinical and radiological data of patients for a mean follow-up of 10 years (SD ± 5.4 years). Phosphoproteomic analyses identified a unique phosphopeptide enrichment pattern which correlates with disease recurrence. Candidate phosphorylated proteins were validated in a large cohort of NF-PitNET patients by western blot and immunohistochemistry. We identified a cluster of 22 phosphopeptides upregulated in recurrent NF-PitNETs compared to non-invasive and invasive subgroups. We reveal significant phosphorylation of the ß-catenin at Ser552 in recurrent and invasive NF-PitNETs, compared to non-invasive/non-recurrent NF-PitNET subgroup. Moreover, ß-catenin pSer552 correlates with the recurrence free survival among 200 patients with NF-PitNET. Together, our results suggest that the phosphorylation status of ß-catenin at Ser552 could act as potential biomarker of tumour recurrence in NF-PitNETs.

Understanding the anomaly of cis-trans isomerism in Pro-His sequence.

The anomalous absence of cisPro stabilizing CαHαXaa···πAro interactions at Xaa-Pro-Aro exclusively when Aro is His, is understood by NMR structural analyses of model peptides, as due to i â†’ i backbone-side chain C6 H-bond that forms uniquely when Aro is His, which significantly decreases its χ1-g- population essential for CαHαXaa···πAro formation.

Design, synthesis, and biological evalution of bifunctional inhibitors against Hsp90-HDAC6 interplay.

HDAC6 and Hsp90, existing as a cytosolic complex play an important role in maintaining the protein homeostasis. The interplay of HDAC6 and Hsp90 has attracted wide attention due to their important role and promise as therapeutic targets in malignant cancers. Therefore, the discovery of dual inhibitors targeting HDAC6 and Hsp90 is of high importance. In the present study, we describe the design, synthesis, and biological evaluation of bifunctional inhibitors against HDAC6 and Hsp90 interplay. In particular, compound 6e shows a significant inhibitory activity against both HDAC6 and Hsp90 with IC50 values of 106 nM and 61 nM, respectively. Compound 6e promotes the acetylation of HDAC6 substrate proteins such as α-tubulin and Hsp90 via HDAC6 inhibition, and also induces the degradation of Hsp90 clients such as Her2, EGFR, Met, Akt, and HDAC6 via Hsp90 inhibition. Compound 6e consequently furnishes potent antiproliferative effect on gefitinib-resistant H1975 non-small cell lung cancer (NSCLC) with a GI50 value of 1.7 µM. In addition, compound 6e successfully achieved significant tumor growth inhibition in H1975 NSCLC xenograft model without noticeable abnormal behavior, body weight changes, and apparent ocular toxicity. We conclude that compound 6e constitutes an excellent tool as well as a valuable lead for assessment of Hsp90 and HDAC6 dual inhibition with a single molecule.

Surgical Outcome Analysis of Large and Giant Petroclival Meningiomas with Special Reference to Quality of Life Issues.

Background: Management strategies for petroclival menigiomas remain controversial. Objectives: We share our experience in management of large and giant true petroclival meniongiomas with special emphasis on patient reported quality of life parameters. Methods: This is a single center study of 47 patients between 2008 and 2018. All patients were checked for tumor specific parameters, clinical parameters, extent of surgical excision, and outcome, as assessed by Karnofsky performance score (KPS), Glasgow outcome score, clinical status, and by SF-36 questionnaire. Results: 32/47 patients' data were assessed. Symptoms included headache (62.5%), involvement of 5th nerve (47%), facial nerve (40.6%), lower cranial nerves (37.5%), cerebellar signs (84%), and long tract signs in (50%) of patients. The mean preoperative KPS was 83.75+/-6.59. Surgical approaches included retromastoid suboccipital craniotomy (50%), Kawase's approach (31.25%), and others in 18.25% patients. 40.625% (n = 13) had a gross total excision, near total resection (NTR) was achieved in 53.125% (n = 17), and 6.25% (n = 2) had a subtotal excision (STE). In 13 patients who had gross total resection (GTR), there were 12 (70.5%) new neurological deficits, while among the 19 patients with NTR, only 5 (29.5%) new neurological deficits were seen. No new onset neurological deficit was seen in patients with STE of tumor. Patient assessed QoL parameters were worse in patients with GTR and best in patients with NTR/STE + GKRS. Conclusion: In patients of large/giant petroclival meningiomas, NTE/STE with adjuvant GKRS provided better preservation of quality of life.

Ruptured cerebral aneurysm in isolated type A interrupted aortic arch managed by transradial endovascular route: A case report with literature review.

BACKGROUND AND INTRODUCTION: Interrupted aortic arch (IAA) is a very rare congenital anomaly carrying high neonatal mortality rate if left untreated. Rarer still, is its presentation in teenage or adulthood. This condition has been found to be complicated with cerebral aneurysms, which is a consequence of hemodynamic stress and hypertension secondary to arch interruption. Cerebral aneurysms can further complicate the clinical course and lead to poor clinical outcomes, especially if ruptured. CLINICAL PRESENTATION: A 17-year-old female presented with ruptured basilar top aneurysm and was considered for endovascular coiling. Transfemoral access was chosen but the catheter could not be negotiated beyond proximal thoracic aorta. A computed tomographic angiography (CTA) of thorax and abdomen was performed, which showed isolated interruption of aortic arch. Subsequently, transradial route was used for coiling of the aneurysm. CONCLUSION: To the best of our knowledge, the index case is one of the only seven cases of IAA with cerebral aneurysm that have been reported till date in medical literature. It also holds the unique distinction of being the first case of IAA with cerebral aneurysm treated by endovascular approach. Our case highlights the importance of transradial access in such pathological conditions.

Extra-Arachnoidal Dissection and Limited Meatal Drilling for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation.

Background: Surgical excision of giant (>4 cm size) vestibular schwannomas (VS) with preservation of facial nerve (FN) function remains a challenge. Objective: Our surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described with the goal of improving FN preservation. Methods: Surgical results with respect to FN preservation were analyzed for two groups of giant VS patients: Group A-operated between 2002 and 2009 using "standard" surgical technique, group B-operated between 2009 and 2016 using extra-arachnoidal dissection and limited meatal drilling. All patients had a minimum follow-up of 1 year. Results: Group A: Of the 115 patients, total excision was possible in 103 (89.5%), near-total in 7 (6%), and subtotal in 5 (4.3%) patients. At a >6-month follow-up, 68 (59.1%) patients had good FN function (House-Brackmann [H&B] grades 1-2), while 21 (18.3%) patients had poor function (H&B grade 3-5). Grade 6 involvement was seen in 26 (22.6%). Five patients had lower cranial nerve impairment necessitating tracheostomy. Group B: Of the 98 patients, total excision was achieved in 70 (71.4%) patients, near-total in 9 (9.2%), and subtotal in 19 (19.4%). Four patients had repeat surgery; 14 underwent gamma-knife radiosurgery. At >6-month follow-up, 78 (79.5%) patients had good FN function (H&B grades 1-2), while 20 (20.4%) had poor function (H&B grade 3-5). Conclusions: With our 'modified' surgical technique of extra-arachnoidal dissection of VS throughout surgery and limited meatal drilling, an improved rate of functional FN preservation was observed.

Extraskeletal Mesenchymal Chondrosarcoma of Central Nervous System - A Rare but Aggressive Tumor: Analysis of Five Cases.

Background: Extraskeletal mesenchymal chondrosarcoma (MCS) of the central nervous system (CNS) is extremely rare. Herein, we present the clinicopathological features of five CNS extraskeletal MCS. Material and Methods: Over the past 10 years, five cases of CNS MCS have been retrieved from in the archives of histopathology department. All biopsies were stained with vimentin, S-100, CD99, desmin, GFAP, INI1, WT1, STAT6, and EMA. Results: There were four males and one female patient in the age group of 1.5-35 years. The clinical and radiological impression was meningioma in three cases, glomus jugulare and primitive neuroectodermal tumor in one case each. All showed classic biphasic morphology, areas of undifferentiated small blue round cells sharply demarcated from the island of cartilage. Three patients experienced multiple recurrences and died subsequently. Conclusion: Extraskeletal MCS of CNS is rare and favors children and young adults. They show aggressive behavior and tend to recur despite surgery and radiotherapy.

The therapeutic role of methotrexate in chronic urticaria: A systematic review.

BACKGROUND: Chronic urticaria, in many cases, has an unsatisfactory response to antihistamines. The current recommendations in urticaria do not mention the dose and duration for methotrexate. AIMS: This study aims to systematically review the use/efficacy of methotrexate in chronic urticaria. METHODS: A systematic search in four databases, that is, PubMed/Medline, Cochrane central, Google Scholar and Clinicaltrials.gov was done to identify studies on the use of methotrexate in chronic urticaria using key words "methotrexate [MeSH terms]" and "urticaria" or "urticaria, chronic" or "urticaria, chronic spontaneous." RESULTS: Nine articles (study participants 127), including three randomized control trials, one prospective interventional trial without control, three retrospective reviews and two case reports, were identified and finally included in the systematic review. There was a paucity of literature and the three randomized control trials did not show any benefit of methotrexate over antihistamines alone. However, in studies where steroid-dependent cases were given methotrexate, marked benefit was reported with steroid-sparing effect, particularly on methotrexate dose escalation. LIMITATIONS: Due to a paucity of published literature on methotrexate in urticaria, a meta-analysis could not be done. CONCLUSION: In chronic recalcitrant or steroid-dependent cases, methotrexate may be a therapeutic agent of interest; however, current evidence does not point to any added advantage in efficacy over antihistamines. More evidence based on larger, well-executed randomized control trials is needed in the future to get more definitive answers.