Publications by authors named "Sathiji Nageshwaran"

We apply a single-molecule chromatin fiber sequencing (Fiber-seq) protocol designed for amplification-free cell-type-specific mapping of the regulatory architecture at nucleosome resolution along extended ∼10-kb chromatin fibers to neuronal and non-neuronal nuclei sorted from human brain tissue. Specifically, application of this method enables the resolution of cell-selective promoter and enhancer architectures on single fibers, including transcription factor footprinting and position mapping, with sequence-specific fixation of nucleosome arrays flanking transcription start sites and regulatory motifs. We uncover haplotype-specific chromatin patterns, multiple regulatory elements cis-aligned on individual fibers, and accessible chromatin at 20,000 unique sites encompassing retrotransposons and other repeat sequences hitherto "unmappable" by short-read epigenomic sequencing.

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Article Synopsis
  • Spinocerebellar ataxia 27B (SCA27B) is a disease that affects balance and coordination, caused by a genetic change in a specific part of a gene called FGF14.
  • Research shows that most brain damage from this disease happens mainly in the cerebellum, which controls movement.
  • In a study of blood samples and brain tissue, scientists found that the genetic change was mostly stable over time, but it exhibited more growth in the cerebellum than in other brain areas, helping to explain why SCA27B mainly affects that part of the brain.
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  • Spinocerebellar ataxia 27B (SCA27B) is an autosomal dominant disorder characterized by GAA•TTC repeat expansions that mainly cause neuronal loss in the cerebellum.
  • A study analyzing blood samples, skin cells, and brain tissues found that the repeat expansions are stable in most peripheral tissues, but significantly more unstable in specific regions of the cerebellum.
  • The cerebellar-specific expansion bias observed could help explain the disease's focused and late-onset impact on cerebellar function in affected individuals.
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  • The study investigates the factors affecting the expansion of tandem repeats, focusing on the FGF14 (GAA)·(TTC) repeat locus in a large sample of 2,530 individuals through advanced sequencing techniques.
  • Researchers discovered a prevalent 5'-flanking variant present in over 70% of alleles, which is linked to nonpathogenic alleles and the ancestral lineage of this genetic marker.
  • This common variant is associated with greater stability of the tandem repeat during inheritance and improved accessibility of chromatin, suggesting a role in preventing pathological expansion.
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Friedreich's ataxia (FA) is caused by a variant of the Frataxin (FXN) gene, leading to its downregulation and progressively impaired cardiac and neurological function. Current gold-standard clinical scales use simplistic behavioral assessments, which require 18- to 24-month-long trials to determine if therapies are beneficial. Here we captured full-body movement kinematics from patients with wearable sensors, enabling us to define digital behavioral features based on the data from nine FA patients (six females and three males) and nine age- and sex-matched controls, who performed the 8-m walk (8-MW) test and 9-hole peg test (9 HPT).

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Vertebrovertebral arteriovenous fistulas (VVAVFs) are rare entities that lack consensus guidelines for their management. Our case describes the successful treatment of a traumatic VVAVF via a contralateral deconstructive endovascular approach. A 64-year-old female presented following a traumatic fall.

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Eisenmenger syndrome refers to any untreated congenital cardiac defect with an intracardiac communication that leads to pulmonary arterial hypertension, reversal of intracardiac shunting, and cyanosis. We describe a 40-year-old cyanotic patient with congenital heart disease with presumed Eisenmenger syndrome who was considered inoperable. Testing revealed a partial atrioventricular septal defect with no evidence of pulmonary arterial hypertension, and the patient underwent successful cardiac repair.

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The outlined protocol describes streamlined methods for the efficient and cost-effective generation of Cas9-associated guide RNAs. Two alternative strategies for guide RNA (gRNA) cloning are outlined based on the usage of the Type IIS restriction enzyme BsmBI in combination with a set of compatible vectors. Outside of the access to Sanger sequencing services to validate the generated vectors, no special equipment or reagents are required aside from those that are standard to modern molecular biology laboratories.

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Heterochromatinisation of pericentromeres, which in mice consist of arrays of major satellite repeats, are important for centromere formation and maintenance of genome stability. The dysregulation of this process has been linked to genomic stress and various cancers. Here we show in mice that the proteasome binds to major satellite repeats and proteasome inhibition by MG132 results in their transcriptional de-repression; this de-repression is independent of cell-cycle perturbation.

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The term "junk DNA" has been reconsidered following the delineation of the functional significance of repetitive DNA regions. Typically associated with centromeres and telomeres, DNA repeats are found in nearly all organisms throughout their genomes. Repetitive regions are frequently heterochromatinized resulting in silencing of intrinsic and nearby genes.

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A 73-year-old man presented in status epilepticus. He had a long history of epilepsy for which he was treated with regular phenytoin and phenobarbitone. On admission, his phenytoin level was found to be subtherapeutic and was treated with rectal diazepam and intravenous lorazepam.

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A 53-year-old Afro-Caribbean woman presented to casualty with a constellation of symptoms pointing to a diagnosis of hypercalcaemia. This was confirmed on laboratory investigation. Findings of a raised serum protein (108 g/l) and normal albumin (35 g/l), lead to an initial working diagnosis of multiple myeloma.

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A 30-year-old woman with generalised DYT1 dystonia, controlled with medication, presented at 9 weeks gestation with an unplanned pregnancy. A number of learning points were highlighted in management of the patient's dystonia alongside pregnancy including avoidance of excessive medication exposure to the fetus, while maintaining symptom control to a level acceptable and safe for the patient and prenatal diagnostic testing. In our case there was no overt ill effect to the newborn.

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