Regulation of embryonic haematopoietic multipotency by EZH1.

All haematopoietic cell lineages that circulate in the blood of adult mammals derive from multipotent haematopoietic stem cells (HSCs). By contrast, in the blood of mammalian embryos, lineage-restricted progenitors arise first, independently of HSCs, which only emerge later in gestation. As best defined in the mouse, 'primitive' progenitors first appear in the yolk sac at 7.5 days post-coitum. Subsequently, erythroid-myeloid progenitors that express fetal haemoglobin, as well as fetal lymphoid progenitors, develop in the yolk sac and the embryo proper, but these cells lack HSC potential. Ultimately, 'definitive' HSCs with long-term, multilineage potential and the ability to engraft irradiated adults emerge at 10.5 days post-coitum from arterial endothelium in the aorta-gonad-mesonephros and other haemogenic vasculature. The molecular mechanisms of this reverse progression of haematopoietic ontogeny remain unexplained. We hypothesized that the definitive haematopoietic program might be actively repressed in early embryogenesis through epigenetic silencing, and that alleviating this repression would elicit multipotency in otherwise lineage-restricted haematopoietic progenitors. Here we show that reduced expression of the Polycomb group protein EZH1 enhances multi-lymphoid output from human pluripotent stem cells. In addition, Ezh1 deficiency in mouse embryos results in precocious emergence of functional definitive HSCs in vivo. Thus, we identify EZH1 as a repressor of haematopoietic multipotency in the early mammalian embryo.

Skull base dural reflection models: tool for teaching neuroanatomy at resource-scarce centers.

Skull base dural reflections are complex, and along with various ligaments joining sutures of the skull base, are related to most important vessels like internal carotid arteries (ICA), vertebral arteries, jugular veins, cavernous sinus, and cranial nerves which make surgical approaches difficult and need thorough knowledge and anatomy for a safe dissection and satisfactory patient outcomes. Cadaver dissection is much more important for the training of skull base anatomy in comparison to any other subspecialty of neurosurgery; however, such facilities are not available at most of the training institutes, more so in low- and middle-income countries (LMICs). A glue gun (100-Watt glue gun, ApTech Deals, Delhi, India) was used to spread glue over the superior surface of the bone of the skull base over desired area (anterior, middle, or lateral skull base). Once glue was spread over the desired surface uniformly, it was cooled under running tap water and the glue layer was separated from the skull base. Various neurovascular impressions were colored for ease of depiction and teaching. Visual neuroanatomy of the inferior surface of dural reflections of the skull base is important for understanding neurovascular orientations of various structures entering or exiting the skull base. It was readily available, reproducible, and simple for teaching neuroanatomy to the trainees of neurosurgery. Skull base dural reflections made up of glue are an inexpensive, reproducible item that may be used for teaching neuroanatomy. It may be useful for trainees and young neurosurgeons, especially at resource-scarce healthcare facilities.

Risk assessment of low arsenic exposure using biomarkers of oxidative and genotoxic stress in a piscine model.

The high level exposure to arsenic induces marked oxidative and genotoxic stress. However, information on the potential of low level arsenic exposure in this context is still scanty. In the present study, the extent of oxidative stress and genetic toxicity induced by low arsenic exposure was explored in freshwater fish Channa punctatus. Fish were exposed to low levels of arsenic (10 and 50 µg L-1) as well as to its high level (500 µg L-1) using sodium arsenite in aquaria water for 14 consecutive days. The TBARS assay for lipid peroxidation exhibited the increased occurrence of oxidative damage in the erythrocytes of fish at both the lower and higher levels of arsenic exposure. The level of reduced glutathione was also elevated in all the three arsenic exposed groups of fish compared to control. In contrast, significant decline was observed in the levels of three major antioxidant enzymes namely, superoxide dismutase, catalase and glutathione peroxidase, upon exposure to higher as well as lower levels of arsenic. Significant increases in micronucleus induction were found in the erythrocytes of fish even at the low levels of arsenic exposure. The study further revealed the occurrence of DNA fragmentation in the erythrocytes of fish at low arsenic exposures as well. The low level exposure to arsenic (using sodium arsenite), therefore, appeared to be capable of inducing noticeable oxidative stress as well as potential genotoxic effect in Channa punctatus. Moreover, the ability of arsenic to induce oxidative stress invariably appeared correlated with its genotoxic potential.

Histone H3K36 methylation regulates pre-mRNA splicing in Saccharomyces cerevisiae.

Co-transcriptional splicing takes place in the context of a highly dynamic chromatin architecture, yet the role of chromatin restructuring in coordinating transcription with RNA splicing has not been fully resolved. To further define the contribution of histone modifications to pre-mRNA splicing in Saccharomyces cerevisiae, we probed a library of histone point mutants using a reporter to monitor pre-mRNA splicing. We found that mutation of H3 lysine 36 (H3K36) - a residue methylated by Set2 during transcription elongation - exhibited phenotypes similar to those of pre-mRNA splicing mutants. We identified genetic interactions between genes encoding RNA splicing factors and genes encoding the H3K36 methyltransferase Set2 and the demethylase Jhd1 as well as point mutations of H3K36 that block methylation. Consistent with the genetic interactions, deletion of SET2, mutations modifying the catalytic activity of Set2 or H3K36 point mutations significantly altered expression of our reporter and reduced splicing of endogenous introns. These effects were dependent on the association of Set2 with RNA polymerase II and H3K36 dimethylation. Additionally, we found that deletion of SET2 reduces the association of the U2 and U5 snRNPs with chromatin. Thus, our study provides the first evidence that H3K36 methylation plays a role in co-transcriptional RNA splicing in yeast.

Manual Instruments as an Alternative to Drilling for Bony Exposure in Skull Base Surgery: Concept and Technique.

Background Drilling in neurosurgery is an integral part of surgical exposure, especially in skull base approaches and craniovertebral junction (CVJ) surgeries. Most of such drillings are done in close proximity to the neurovascular structures in skull base surgeries and cervical-medullary junction or facet/pedicle in CVJ surgeries. Reluctance to drilling among young neurosurgeons is due to less hands-on experience during training and also, in the early part of the career, due to fear of injury to neurovascular structures. Methods Five commonest bone removals for skull base region and CVJ surgeries that can be safely done using manual instruments were identified based on experiences of senior authors. The authors highlight key technical nuances to widen surgical corridors using manual instruments safely for skull base surgical approaches. Results Basic neuroanatomical concepts and basic physics help in using manual instruments safely for bone removals in various skull base surgical approaches. Conclusions Manual instruments may be used for bone removals in selected skull base surgical approaches, which help young neurosurgeons to perform these surgeries in limited-resource settings.

Setting Up a Department of Neurosurgery in a Government Hospital in an LMIC: Jodhpur, India.

BACKGROUND: The number of government institutes offering affordable super specialty and tertiary healthcare in India has traditionally not been able to keep pace with the growth in population, most of whom are too poor to be able to afford private healthcare services. To meet this mandate, 6 new institutes built on the template of the premier institute of the country-the All India Institute of Medical Sciences, New Delhi-were founded and began operations in 2012. Using the progress of our department as an example, the aim of this report is to outline the principles that were followed to set up the department of neurosurgery. METHODS: The Department of Neurosurgery at All India Institute of Medical Sciences, Jodhpur, began providing services in August 2017. Data related to the inception and development of the department were collected. RESULTS: The department has grown during the past 5 years from 400 outpatients and 79 inpatients in 2017 to 11,144 outpatients and 1624 inpatients in 2022. Only 59 surgeries were performed in 2017 compared with 597 routine and 311 emergency procedures performed in 2022. Currently, the department has 7 faculty members performing all forms of complex skull base, craniovertebral junction, vascular, endovascular, epilepsy, and functional surgeries. A total of 134 studies have been reported in national and international journals, and 8 patents have been granted. CONCLUSIONS: We report the unique experiences of one department that could be useful as a template and as guidelines for the establishment process of a new department.

Morphometric Comparison of Endoscopic Endonasal Transpterygoid and Precaruncular Contralateral Medial Transorbital Approaches to Sphenoid Sinus Lateral Recess.

BACKGROUND AND OBJECTIVES: The endoscopic endonasal transpterygoid approach (TPA), minimally invasive compared with the sublabial transmaxillary and transcranial approaches, still accounts for morbidity in benign lateral recess of sphenoid sinus (LRSS) pathologies. Others have suggested an alternative route to the LRSS, the endoscopic contralateral medial transorbital approach (cMTO). However, no quantitative evidence exists to support the clinical application of this approach. This cadaveric study, in a controlled laboratory setting, provides a morphometric comparison of the TPA and cMTO for accessing the LRSS. The study also details the anatomy and technical nuances for optimizing the cMTO corridor. METHODS: Ten fresh preinjected human cadaveric specimens (20 sides) were dissected with neuronavigation, completing endoscopic cMTO and TPA on each side. Four parameters-working distance to lateral recess, surgical exposure area, angle of attack (AoA), and surgical freedom-were measured for each approach. Relevant osteological measurements in 10 dried human skulls were recorded. RESULTS: The mean distance from the superior margin of the lacrimal sac impression to the inferior margin of the trochlear fossa was 10.29 ± 1.13 mm, and that from the anterior ethmoidal artery foramina to the posterior lacrimal crest was 9.63 ± 1.23 mm. The mean exposure area around the LRSS was significantly higher in TPA (614.09 ± 40.38 mm2) than in cMTO (391.19 ± 59.01 mm2, P = .001). The mean AoA was 9.83° and 10.24° in the cMTO and TPA, respectively, in the craniocaudal direction (P = .529). In the horizontal plane, it was 9.29° and 10.76° (P = .012). There was no significant difference in surgical freedom between the cMTO and TPA (804.61 and 806.05 mm3, respectively; P = .993). CONCLUSION: Although comparatively limited exposure area, the cMTO approach has a similar AoA and surgical freedom as TPA and offers better visualization and ergonomic advantages. cMTO provides a feasible, less morbid, multiport technique for benign sphenoid sinus lateral recess pathologies.

Suction cannula design for safe microneurosurgery.

INTRODUCTION: Suction cannula (SC) is an important instrument for a neurosurgeon. Currently used suction control valves, kept in the sterile field, are controlled by the surgeon, for which he needs to leave the surgical dissection or by assistant or by operation room personnel to adjust the pressure of the equipment (suction machine or central suction), which lies in the unsterile field. Authors studied relationships of the different diameters of SC and the thumb hole (TH) of the SC and present their findings. METHODS: Seven SC with various diameters of their lumen and TH were used for the study. Suction pressures were measured with suction tip open, immersed in saline and TH open and closed. TH of 2 SC were made smaller using adhesive tape over the TH and making smaller hole over the tape and two additional measurements were taken using changed SC with modified TH. SPSS Statistics 23.0 (IBM India Pvt Ltd, Bangaluru, India) was used for statistical analysis of the pressure recordings and SC features. RESULTS: Pressure and diameter of ST or TH were related in opposite direction. As the diameter increases the pressure decreases. A strong negative association was observed between the diameter of TH and the pressure. CONCLUSION: TH diameter of SC is important to control suction pressure with any size of SC. One should use tear-drop type TH or appropriate diameter of the circular type of TH to contemplate safe microneurosurgery.

The Yin and Yang of Operating on a Posterior Fossa Meningioma: The Schmahmann Syndrome.

The cerebellum is classically linked with control of motor function, such as coordination, balance, and regulation of movement. There is an increasing awareness, now, of the non-motor functions of the cerebellum, and the occurrence of behavioral anomalies with cerebellar disorders. We present the first report of Schmahmann syndrome (cerebellar cognitive affective syndrome [CCAS]) occurring secondary to posterior fossa meningioma excision. A 35-year-old lady with a posterior fossa meningioma developed an infarct of the right posterosuperior cerebellar hemisphere and ipsilateral superior vermis, following suboccipital craniotomy and tumor resection. Few days after the surgery, she presented with aggressive and emotional behavior, irrelevant talk, and emotional lability. The CCAS scale was administered, and she scored poorly on almost all parameters. A neuropsychological evaluation was also done. The occurrence of CCAS, posterior fossa syndrome (PFS), and behavioral abnormalities like abnormal pathological laughter/crying provides further clinical evidence of the "affective" functions of the cerebellum, modulated mainly by the posterior lobe and vermis of the cerebellum.

EZH1 repression generates mature iPSC-derived CAR T cells with enhanced antitumor activity.

Human induced pluripotent stem cells (iPSCs) provide a potentially unlimited resource for cell therapies, but the derivation of mature cell types remains challenging. The histone methyltransferase EZH1 is a negative regulator of lymphoid potential during embryonic hematopoiesis. Here, we demonstrate that EZH1 repression facilitates in vitro differentiation and maturation of T cells from iPSCs. Coupling a stroma-free T cell differentiation system with EZH1-knockdown-mediated epigenetic reprogramming, we generated iPSC-derived T cells, termed EZ-T cells, which display a highly diverse T cell receptor (TCR) repertoire and mature molecular signatures similar to those of TCRαß T cells from peripheral blood. Upon activation, EZ-T cells give rise to effector and memory T cell subsets. When transduced with chimeric antigen receptors (CARs), EZ-T cells exhibit potent antitumor activities in vitro and in xenograft models. Epigenetic remodeling via EZH1 repression allows efficient production of developmentally mature T cells from iPSCs for applications in adoptive cell therapy.

Volume Rendering Technique (VRT) for Planning and Learning Cranio-Vertebral Junction (CVJ) Surgeries: Technical Note.

AIM: To present the application of volume rendering technique (VRT) of computed tomography (CT) scan in cranio-vertebral junction (CVJ) surgeries. MATERIAL AND METHODS: The authors used VRT images of CT scan in patients of congenital CVJ anomalies who were subjected to various surgeries through midline posterior approach. The screw entry points and courses of vertebral arteries were identified in relation to various landmarks on the VRT images, preoperatively and intra-operatively. RESULTS: A total of 15 patients of CVJ anomalies, who underwent surgeries through midline posterior approach, formed the study group. The screw entry points and courses of the vertebral arteries could be effectively identified in the surgical fields. CONCLUSION: We conclude that VRT images are an inexpensive and user friendly tool to identify the screw insertion points in the surgeries of CVJ anomalies. They also help in identifying the course of the vertebral artery in the surgical field. On the whole, their use makes the surgery in this region, safer.

LIN28B alters ribosomal dynamics to promote metastasis in MYCN-driven malignancy.

High expression of LIN28B is associated with aggressive malignancy and poor survival. Here, probing MYCN-amplified neuroblastoma as a model system, we showed that LIN28B expression was associated with enhanced cell migration in vitro and invasive and metastatic behavior in murine xenografts. Sequence analysis of the polyribosome fraction of LIN28B-expressing neuroblastoma cells revealed let-7-independent enrichment of transcripts encoding components of the translational and ribosomal apparatus and depletion of transcripts of neuronal developmental programs. We further observed that LIN28B utilizes both its cold shock and zinc finger RNA binding domains to preferentially interact with MYCN-induced transcripts of the ribosomal complex, enhancing their translation. These data demonstrated that LIN28B couples the MYCN-driven transcriptional program to enhanced ribosomal translation, thereby implicating LIN28B as a posttranscriptional driver of the metastatic phenotype.

Suction Pressure Control Valve for Microneurosurgery.

A suction pressure control valve (SPCV) for microneurosurgery is designed to place control of safe suction pressure in the hands of an operating neurosurgeon. Tumor tissue needs more negative suction pressure as compared to normal brain tissue, cranial nerves, and vessels in the neurosurgical operating field. The authors present the details of a prototype of a simple and inexpensive device for dynamic adjustment of negative suction pressure by the surgeon or the assistant while working on different tissue types during microneurosurgery.

Three-Dimensional Volume Rendering: An Underutilized Tool in Neurosurgery.

OBJECTIVE: Two-dimensional radiologic images of computed tomography (CT) and magnetic resonance imaging (MRI) examinations are insufficient to provide three-dimensional conception of intracranial or spinal lesions, especially for an inexperienced neurosurgeon. We share our experience of applications of volume rendering (VR) images of CT and MRI studies of brain and spine for the purpose of training and surgical planning in neurosurgery. METHODS: Digital Imaging and Communications in Medicine viewer software was used on a personal computer/laptop to view CT and MRI examinations of various lesions of brain, spine, and spinal cord. Various user-friendly applications of the software enable users to edit the images acquired. RESULTS: Imaging technique (CT and MRI) incorporating continuous or overlapping slice with slice thickness of 1 mm with zero gap provides adequate three-dimensional image quality on personal computer/laptop acquired by VR. It was especially helpful for assessment of lesions of the skull base, intracranial vessels (aneurysm and arteriovenous malformation), craniovertebral junction and contrast-enhancing lesions of the brain. Displaying VR images in the operating room as per the patient's head position orients the surgeon to identify various structures in the surgical field. CONCLUSIONS: VR is underused in neurosurgery. It enables inexperienced neurosurgeons to understand morphologic details of a lesion and important osteoneurovascular structures around it. It is also helpful for training and preoperative planning in selected patients in neurosurgery.

Frugal Malleable Microdissectors and Arachnoid Knives for Microneurosurgery.

BACKGROUND: Similar to most of the other medical and surgical fields, neurosurgery has changed drastically in recent decades, especially in instrumentation and equipment. Safety, scope of treating initially considered nontreatable neurosurgical conditions, and prognosis of most neurosurgical procedures have improved significantly. Newer instruments and equipments are being introduced exponentially, leading to tremendous cost escalation of neurosurgical treatment. However, equitable distribution of neurosurgical services in society is far from reality. We need to look back and learn from our teachers and forefathers of neurosurgery their innovative ways to accomplish difficult procedures without advanced tools and techniques. Microneurosurgery is considered a highly skilled technique, and instruments used for it are delicate, precise, and costlier than similar instruments for macroneurosurgery. TECHNIQUE AND CONCLUSION: Frugal innovative techniques and tools are presented for making stainless steel wire and plate microdissectors that are effective for microneurosurgical procedures and can be helpful for neurosurgeons working in resource-poor settings.

Skull Base Surgery with Minimal Resources.

BACKGROUND: Skull base surgery needs advanced equipment and is performed at few public sector hospitals in India. For financial and infrastructure reasons, the facilities available are insufficient for the large number of poor patients who need this surgery. METHODS: Neurologically deteriorating poor patients who failed to receive skull base surgery at overloaded public sector hospitals underwent surgery with basic neurosurgical instruments, using the available resources and indigenously designed instruments adhering to the basic principles of skull base surgery. Various lesions operated on in the study were analyzed based on their location and surgical approach. RESULTS: Ninety-one skull base surgeries in 84 patients were performed during 2013-2015. There were 46 males and 38 females, with an average age of 35 years. Surgical treatment included surgery of the craniovertebral junction (n = 43) and lesions of the anterior skull base (n = 7), middle skull base (n = 10), and posterior skull base (n = 31). Lesions were operated on through anterior (n = 10), lateral (n = 14), and posterior and posterolateral (n = 67) skull base approaches. CONCLUSIONS: The facilities available in low-income countries such as India are insufficient to take care of poor patients who need skull base surgery. Indigenous innovations, use of the available resources, and interdisciplinary coordination help overcome the challenges of resource scarcity to a reasonable extent in many ill-equipped public sector hospitals for the safe and efficient management of many patients who need skull base surgery.

Redundant Functions for Nap1 and Chz1 in H2A.Z Deposition.

H2A.Z is a histone H2A variant that contributes to transcriptional regulation, DNA damage response and limits heterochromatin spreading. In Saccharomyces cerevisiae, H2A.Z is deposited by the SWR-C complex, which relies on several histone chaperones including Nap1 and Chz1 to deliver H2A.Z-H2B dimers to SWR-C. However, the mechanisms by which Nap1 and Chz1 cooperate to bind H2A.Z and their contribution to H2A.Z deposition in chromatin is not well understood. Using structural modeling and molecular dynamics simulations, we identify a series of H2A.Z residues that form a chaperone-specific binding surface. Mutation of these residues revealed different surface requirements for Nap1 and Chz1 interaction with H2A.Z. Consistent with this result, we found that loss of Nap1 or Chz1 individually resulted in mild defects in H2A.Z deposition, but that deletion of both Nap1 and Chz1 resulted in a significant reduction of H2A.Z deposition at promoters and led to heterochromatin spreading. Together, our findings reveal unique H2A.Z surface dependences for Nap1 and Chz1 and a redundant role for these chaperones in H2A.Z deposition.

Direct one-pot synthesis of glutathione capped hydrophilic FePt-CdS nanoprobe for efficient bimodal imaging application.

One-pot synthesis methods for development of hydrophilic imaging nanoprobes have advantages over multi-pot methods due to their simple procedures, less probability for degradation of efficiency, superior control over growth and morphology, cost effectiveness, improved scope for scale-up synthesis etc. Here, we present a novel one-pot facile synthesis of hydrophilic colloidal bimodal nanoprobe (FePt-CdS) prepared through a seed-mediated nucleation and growth technique. In this facile synthesis of complex nanostructure, glutathione (GSH) was used as the capping agent to render biocompatibility and dispersibility. The microstructure, surface, optical, magnetic, biocompatibility, relaxivity and imaging property of the developed nanoprobe have been studied. The microstructural characterizations reveal average size of the particle as ~9-11nm with bleb shaped morphology. Spectroscopic characterization depicts the development of GSH capped CdS QDs on FePt, surface functionalities and their stability. The magnetic measurements confirm the superparamagnetic property in the developed bimodal nanoprobe. In addition, the GSH capping imparts excellent biocompatibility, water dispersibility, and fluorescence property to the probe. In RAW 264.7 macrophage cells, the bimodal nanoprobes exhibit intense green and red fluorescence. The magnetic resonance imaging (MRI) and fluorescence imaging (FI) study depict high transverse relaxivity and visible range fluorescent property in the synthesized FePt-CdS nanoprobe. Hence, the developed bimodal nanoprobe can be used as a potential candidate in simultaneous FI and MR imaging.

Endoscopic transoral surgery for craniovertebral junction anomalies. Technical note.

Craniovertebral junction (CVJ) anomalies continue to be challenging for neurosurgeons because of the complex anatomy of this region. To date, microsurgical decompression via a transoral route is the standard treatment for anteriorly located compressive lesions of the cervicomedullary junction (CMJ). The results obtained by minimizing surgical trauma are fewer complications, shorter hospital stays, and reduced overall psychological burden. Endoscopic surgery is becoming a leading modality in minimally invasive neurosurgical treatment. The authors performed surgery in 11 patients with irreducible osseous dislocations resulting from CVJ abnormality during a 2-year period. Anterior CMJ decompression was achieved in all patients by performing neuroendoscopically controlled transoral excision of bone and soft tissues. The surgical technique and results will be discussed. The use of the endoscope offers several advantages in cases requiring a transoral approach to the lower clivus and atlantoaxial region. The use of minimally invasive endoscopic techniques has the potential to reduce the need for a wider cranial base opening and to decrease postoperative complications.

Supratentorial metastasis of medulloblastoma in adults.

Two adults, 31 and 20 years of age, developed supratentorial metastasis 3½ years and 11 months, respectively, after gross total removal of their posterior fossa medulloblastoma. The first case developed spinal metastasis as well. Both had undergone craniospinal irradiation. Case 1 underwent laminectomy and case 2 underwent craniotomy because their presenting symptoms required so.