Predicting small molecule binding pockets on diacylglycerol kinases using chemoproteomics and AlphaFold.

Diacylglycerol kinases (DGKs) are metabolic kinases involved in regulating cellular levels of diacylglycerol and phosphatidic lipid messengers. The development of selective inhibitors for individual DGKs would benefit from discovery of protein pockets available for inhibitor binding in cellular environments. Here we utilized a sulfonyl-triazole probe (TH211) bearing a DGK fragment ligand for covalent binding to tyrosine and lysine sites on DGKs in cells that map to predicted small molecule binding pockets in AlphaFold structures. We apply this chemoproteomics-AlphaFold approach to evaluate probe binding of DGK chimera proteins engineered to exchange regulatory C1 domains between DGK subtypes (DGKα and DGKζ). Specifically, we discovered loss of TH211 binding to a predicted pocket in the catalytic domain when C1 domains on DGKα were exchanged that correlated with impaired biochemical activity as measured by a DAG phosphorylation assay. Collectively, we provide a family-wide assessment of accessible sites for covalent targeting that combined with AlphaFold revealed predicted small molecule binding pockets for guiding future inhibitor development of the DGK superfamily.

Congenital Melanocytic Nevus with Scrotal Mass: A Diagnostic Dilemma.

Congenital melanocytic nevus is deposition of pigment producing cells of melanocytic lineage in the dermis. We present an extremely rare case of congenital melanocytic nevus with a scrotal mass associated with deposition of melanin in the brain. The mass may mimic like a testicular tumour on clinical presentation.

Fatty acid chain length drives lysophosphatidylserine-dependent immunological outputs.

In humans, lysophosphatidylserines (lyso-PSs) are potent lipid regulators of important immunological processes. Given their structural diversity and commercial paucity, here we report the synthesis of methyl esters of lyso-PS (Me-lyso-PSs) containing medium- to very-long-chain (VLC) lipid tails. We show that Me-lyso-PSs are excellent substrates for the lyso-PS lipase ABHD12, and that these synthetic lipids are acted upon by cellular carboxylesterases to produce lyso-PSs. Next, in macrophages we demonstrate that VLC lyso-PSs orchestrate pro-inflammatory responses and in turn neuroinflammation via a Toll-like receptor 2 (TLR2)-dependent pathway. We also show that long-chain (LC) lyso-PSs robustly induce intracellular cyclic AMP production, cytosolic calcium influx, and phosphorylation of the nodal extracellular signal-regulated kinase to regulate macrophage activation via a TLR2-independent pathway. Finally, we report that LC lyso-PSs potently elicit histamine release during the mast cell degranulation process, and that ABHD12 is the major lyso-PS lipase in these immune cells.

Leukoencephalopathy with Calcifications and Cysts in a Child with Progressive Hemiparesis-A Case Report.

With the advent of modern neuroimaging, the imaging features of various leukoencephalopathies have been unraveled in the past two decades. Leukoencephalopathy with calcifications and cysts (LCC) is one such rare autosomal recessive disorder with marked clinical heterogeneity and a striking but characteristic imaging appearance-diffuse white matter changes, intraparenchymal cysts, and calcifications. The calcifications in LCC are characteristically nodular, dense, bulky, and predominantly located in gray nuclei of the central brain (basal ganglia, thalami) and cerebellum (dentate nuclei). We describe a case of a 9-year-old boy with progressive left hemiparesis and seizures, which on imaging showed characteristic features of LCC. We further review the neuroimaging features of LCC and its differential diagnoses.

Clinico-radiological-pathological correlation in eumycetoma spectrum: Case series.

Maduramycosis or mycetoma is one of the chronic granulomatous diseases commonly seen in tropical regions. Microbiological cultures and biopsy are carried out for the definitive diagnosis of the disease, but they are time-consuming methods. The present study aims to correlate clinical, radiological and pathological features in eumycetoma cases to emphasize the role of "dot in circle" sign leading to early imaging-based diagnosis. Imaging plays an important role in early diagnosis of mycetoma, which has therapeutic implications. "Dot in circle" sign is a recently described sign in mycetoma cases on ultrasound (USG) and magnetic resonance imaging (MRI). We diagnosed four cases of eumycetoma based on clinical and imaging features, which were confirmed with histopathology. The differential diagnosis, which may mimic this sign is also discussed. The "dot in circle" sign is seen on both ultrasound and MRI. This sign is highly specific for mycetomas. Knowledge of this sign can help in early diagnosis of mycetomas preventing misdiagnosis and further complications.

Temporal encephalocele into transverse sinus in an adult with partial seizures: MRI evaluation of a rare site of brain herniation.

Herniation of brain parenchyma outside its normal enclosure (also known as encephalocele) has long been known to occur at certain classic sites and is classified accordingly. With widespread use of modern neuroimaging, the previously unknown atypical and rare sites of encephalocele have now been identified. Brain herniation into a dural venous sinus is one such recently described entity with case reports extending only upto the earlier part of this decade. With no definite clinical symptomatology, imaging is crucial to diagnose this lesion accurately and differentiate it from the more familiar entity in this region of the brain, the arachnoid granulations. Also known as occult encephalocele, focal brain herniation into dural venous sinus has few specific imaging features and characteristic sites. We report a case of a 21-year-old man with partial seizures in whom MRI of the brain revealed focal herniation of the normal temporal lobe parenchyma into the left transverse sinus and discuss the key imaging features and pathophysiology of this entity.

MRI evaluation of Kimura's disease with emphasis on diffusion weighted imaging and enhancement characteristics.

Kimura's disease is a rare disease of the head and neck region affecting mainly the adult males in eastern countries. The parotid and periparotid subcutaneous regions are the most common sites in head and neck region. Coupled with peripheral eosinophilia and raised serum IgE levels as characteristic features on hemogram, a painless swelling in parotid and periparotid region is diagnostic of Kimura's disease. Magnetic resonance imaging (MRI) has been an important modality in evaluating lesions of the head and neck region. Recently, interest in the diffusion weighted imaging (DWI) and contrast enhanced MRI (CEMRI) imaging of lesions in Kimura's disease has been noted to characterize it and differentiate it from other pathologies. We describe a case a recurrent Kimura's disease of the periparotid region and its MRI features with special emphasis on its characteristics on DWI and contrast enhanced sequences.

Dural Ectasia of the Optic Nerve: A Rare Presentation in Neurofibromatosis Type I.

Neurofibromatosis Type 1 (NF-1) is a common neurocutaneous syndrome with a characteristic spectrum of pathologies affecting the optic pathway. Optic pathway glioma and optic nerve meningioma are two such common afflictions of the optic nerve in NF-1. Dural ectasia of the optic nerve also known as optic nerve meningocele is a rare manifestation of optic nerve involvement in NF-1. Magnetic resonance imaging (MRI) is an excellent modality to accurately identify, characterize, delineate, and differentiate dural ectasia of the optic nerve from the commoner lesions such as optic glioma and meningioma in NF-1. We describe a case of a young woman with NF and a large recurrent palpebral neurofibroma. MRI evaluation of the orbits revealed extensive ectasia of the dura lining the cerebrospinal fluid sheath around all the segments of the optic nerve and around the optic chiasm.

Unilateral Cerebellar Hypoplasia: A Rare Cause of Childhood Seizures.

Cerebellar malformations are a rare group of disorders with clinical heterogeneity. The usual posterior fossa malformations comprise of the cystic lesions like Dandy-walker complex, enlarged cisterna magna or arachnoid cysts. The vermis is a commonly associated structure in both cystic and non-cystic posterior fossa malformations. The congenital malformations affecting the cerebellar parenchyma are however very rare. Magnetic resonance imaging (MRI) is an excellent modality to detect and accurately classify these malformations. We describe a case of 14 years old boy with unilateral cerebellar hypoplasia and recurrent seizures with emphasis on the MRI features of this rare entity.

Biochemical characterization of the PHARC-associated serine hydrolase ABHD12 reveals its preference for very-long-chain lipids.

Polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract (PHARC) is a rare genetic human neurological disorder caused by null mutations to the Abhd12 gene, which encodes the integral membrane serine hydrolase enzyme ABHD12. Although the role that ABHD12 plays in PHARC is understood, the thorough biochemical characterization of ABHD12 is lacking. Here, we report the facile synthesis of mono-1-(fatty)acyl-glycerol lipids of varying chain lengths and unsaturation and use this lipid substrate library to biochemically characterize recombinant mammalian ABHD12. The substrate profiling study for ABHD12 suggested that this enzyme requires glycosylation for optimal activity and that it has a strong preference for very-long-chain lipid substrates. We further validated this substrate profile against brain membrane lysates generated from WT and ABHD12 knockout mice. Finally, using cellular organelle fractionation and immunofluorescence assays, we show that mammalian ABHD12 is enriched on the endoplasmic reticulum membrane, where most of the very-long-chain fatty acids are biosynthesized in cells. Taken together, our findings provide a biochemical explanation for why very-long-chain lipids (such as lysophosphatidylserine lipids) accumulate in the brains of ABHD12 knockout mice, which is a murine model of PHARC.

Quantitative Computed Tomography (CT) Assessment of Emphysema in Patients with Severe Chronic Obstructive Pulmonary Disease (COPD) and its Correlation with Age, Sex, Pulmonary Function Tests, BMI, Smoking, and Biomass Exposure.

BACKGROUND: To evaluate the role of HRCT in quantifying emphysema in severe COPD patients and to study the variations in the pattern of emphysema in relation to age, sex, FEV1, smoking index, biomass exposure, and BMI. MATERIAL/METHODS: Automatic lung segmentation of HRCT scans in 41 severe COPD patients (GOLD stage III or more) was done using an emphysema protocol. The extent of emphysema was assessed using the density mask method with a threshold of -950 HU (%LAA-950). The percentage of emphysema in each lung lobe and both lungs was correlated with 6 parameters - age, sex, BMI, smoking index, biomass exposure, and FEV1. RESULTS: Smoking resulted in homogenously distributed emphysema regardless of the severity of smoking. BMI was inversely correlated with the extent of emphysema. A significant association was found between the percentage of emphysema in the right lower lobe and BMI (P=0.015), between biomass exposure and the percentage of emphysema in RUL, RLL, and both lungs (P values of 0.024, 0.016, and 0.036, respectively). The extent of emphysema was disproportionately low compared to the amount of obstruction on PFTs, indicating an airway predominant variety of COPD with significant biomass exposure. CONCLUSIONS: Smoking is associated with a relatively homogenous distribution of emphysema with no regional predilection. Biomass exposure produces predominantly right-sided emphysema. BMI decreases with increasing levels of emphysema in the right lower lobe. These risk factors of emphysema patterns are helpful in deciding on the management, including surgical options.