Explore the vast range of titles available.

Antibodies have diverse applications due to their high reaction specificities but are sensitive to denaturation when a higher working temperature is required. We have developed a simple, highly scalable and generalizable chemical approach for stabilizing off-the-shelf antibodies against thermal and chemical denaturation. We demonstrate that the stabilized antibodies (termed SPEARs) can withstand up to 4 weeks of continuous heating at 55 °C and harsh denaturants, and apply our method to 33 tested antibodies. SPEARs enable flexible applications of thermocycling and denaturants to dynamically modulate their binding kinetics, reaction equilibrium, macromolecular diffusivity and aggregation propensity. In particular, we show that SPEARs permit the use of a thermally facilitated three-dimensional immunolabeling strategy (termed ThICK staining), achieving whole mouse brain immunolabeling within 72 h, as well as nearly fourfold deeper penetration with threefold less antibodies in human brain tissue. With faster deep-tissue immunolabeling and broad compatibility with tissue processing and clearing methods without the need for any specialized equipment, we anticipate the wide applicability of ThICK staining with SPEARs for deep immunostaining. Thermostable antibodies called SPEARs enable rapid immunostaining with improved tissue penetration.

Bone is a dynamic tissue constantly responding to environmental changes such as nutritional and mechanical stress. Bone homeostasis in adult life is maintained through bone remodeling, a controlled and balanced process between bone-resorbing osteoclasts and bone-forming osteoblasts. Osteoblasts secrete matrix, with some being buried within the newly formed bone, and differentiate to osteocytes. During embryogenesis, bones are formed through intramembraneous or endochondral ossification. The former involves a direct differentiation of mesenchymal progenitor to osteoblasts, and the latter is through a cartilage template that is subsequently converted to bone. Advances in lineage tracing, cell sorting, and single-cell transcriptome studies have enabled new discoveries of gene regulation, and new populations of skeletal stem cells in multiple niches, including the cartilage growth plate, chondro-osseous junction, bone, and bone marrow, in embryonic development and postnatal life. Osteoblast differentiation is regulated by a master transcription factor RUNX2 and other factors such as OSX/SP7 and ATF4. Developmental and environmental cues affect the transcriptional activities of osteoblasts from lineage commitment to differentiation at multiple levels, fine-tuned with the involvement of co-factors, microRNAs, epigenetics, systemic factors, circadian rhythm, and the microenvironments. In this review, we will discuss these topics in relation to transcriptional controls in osteogenesis.

Studying chemosensory processing desires precise chemical cue presentation, behavioral response monitoring, and large-scale neuronal activity recording. Here we present Fish-on-Chips, a set of optofluidic tools for highly-controlled chemical delivery while simultaneously imaging behavioral outputs and whole-brain neuronal activities at cellular resolution in larval zebrafish. These include a fluidics-based swimming arena and an integrated microfluidics-light sheet fluorescence microscopy (µfluidics-LSFM) system, both of which utilize laminar fluid flows to achieve spatiotemporally precise chemical cue presentation. To demonstrate the strengths of the platform, we used the navigation arena to reveal binasal input-dependent behavioral strategies that larval zebrafish adopt to evade cadaverine, a death-associated odor. The µfluidics-LSFM system enables sequential presentation of odor stimuli to individual or both nasal cavities separated by only ~100 µm. This allowed us to uncover brainwide neural representations of cadaverine sensing and binasal input summation in the vertebrate model. Fish-on-Chips is readily generalizable and will empower the investigation of neural coding in the chemical senses. Studying chemosensory processing desires precise chemical cue presentation, behavioral response monitoring, and large-scale neuronal activity recording. Here, the authors report a fluidics-based toolkit for studying chemosensation in larval zebrafish, and used it to reveal the brainwide neural representations of cadaverine sensing and its binasal input-dependent behavioral avoidance.

According to current dogma, chondrocytes and osteoblasts are considered independent lineages derived from a common osteochondroprogenitor. In endochondral bone formation, chondrocytes undergo a series of differentiation steps to form the growth plate, and it generally is accepted that death is the ultimate fate of terminally differentiated hypertrophic chondrocytes (HCs). Osteoblasts, accompanying vascular invasion, lay down endochondral bone to replace cartilage. However, whether an HC can become an osteoblast and contribute to the full osteogenic lineage has been the subject of a century-long debate. Here we use a cell-specific tamoxifen-inducible genetic recombination approach to track the fate of murine HCs and show that they can survive the cartilage-to-bone transition and become osteogenic cells in fetal and postnatal endochondral bones and persist into adulthood. This discovery of a chondrocyte-to-osteoblast lineage continuum revises concepts of the ontogeny of osteoblasts, with implications for the control of bone homeostasis and the interpretation of the underlying pathological bases of bone disorders.

Telomerase reverse transcriptase (TERT) promoter (pTERT) mutation has often been described as a late event in gliomagenesis and it has been suggested as a prognostic biomarker in gliomas other than 1p19q codeleted tumors. However, the characteristics of isocitrate dehydrogenase (IDH) wild type (wt) (IDHwt), pTERTwt glioblastomas are not well known. We recruited 72 adult IDHwt, pTERTwt glioblastomas and performed methylation profiling, targeted sequencing, and fluorescence in situ hybridization (FISH) for TERT structural rearrangement and ALT (alternative lengthening of telomeres). There was no significant difference in overall survival (OS) between our cohort and a the Cancer Genome Atlas (TCGA) cohort of IDHwt, pTERT mutant (mut) glioblastomas, suggesting that pTERT mutation on its own is not a prognostic factor among IDHwt glioblastomas. Epigenetically, the tumors clustered into classic‐like (11%), mesenchymal‐like (32%), and LGm6‐glioblastoma (GBM) (57%), the latter far exceeding the corresponding proportion seen in the TCGA cohort of IDHwt, pTERTmut glioblastomas. LGm6‐GBM‐clustered tumors were enriched for platelet derived growth factor receptor alpha (PDGFRA) amplification or mutation (p = 0.008), and contained far fewer epidermal growth factor receptor (EGFR) amplification (p < 0.01), 10p loss (p = 0.001) and 10q loss (p < 0.001) compared with cases not clustered to this group. LGm6‐GBM cases predominantly showed ALT (p = 0.038). In the whole cohort, only 35% cases showed EGFR amplification and no case showed combined chromosome +7/−10. Since the cases were already pTERTwt, so the three molecular properties of EGFR amplification, +7/−10, and pTERT mutation may not cover all IDHwt glioblastomas. Instead, EGFR and PDGFRA amplifications covered 67% and together with their mutations covered 71% of cases of this cohort. Homozygous deletion of cyclin dependent kinase inhibitor 2A (CDKN2A)/B was associated with a worse OS (p = 0.031) and was an independent prognosticator in multivariate analysis (p = 0.032). In conclusion, adult IDHwt, pTERTwt glioblastomas show epigenetic clustering different from IDHwt, pTERTmut glioblastomas, and IDHwt glioblastomas which are pTERTwt may however not show EGFR amplification or +7/−10 in a significant proportion of cases. CDKN2A/B deletion is a poor prognostic biomarker in this group.

The mechanisms underlying the emergence of learned motor skill representation in primary motor cortex (M1) are not well understood. Specifically, how motor representation in the deep output layer 5b (L5b) is shaped by motor learning remains virtually unknown. In rats undergoing motor skill training, we detect a subpopulation of task-recruited L5b neurons that not only become more movement-encoding, but their activities are also more structured and temporally aligned to motor execution with a timescale of refinement in tens-of-milliseconds. Field potentials evoked at L5b in vivo exhibit persistent long-term potentiation (LTP) that parallels motor performance. Intracortical dopamine denervation impairs motor learning, and disrupts the LTP profile as well as the emergent neurodynamical properties of task-recruited L5b neurons. Thus, dopamine-dependent recruitment of L5b neuronal ensembles via synaptic reorganization may allow the motor cortex to generate more temporally structured, movement-encoding output signal from M1 to downstream circuitry that drives increased uniformity and precision of movement during motor learning. Motor learning induces structural and functional reorganization in upper layers of motor cortex. Here the authors show that neuronal ensembles in the output layer 5b exhibit temporal dynamics during skilled learning that progressively becomes well-aligned to movement in a dopamine dependent manner.

Background: Spinal metastasis is a rare complication of supratentorial glioblastoma. We report the clinical features and prognosis of this phenomenon and review the relevant literature. Methods: This is a territory-wide, multicentre, retrospective review using data from the Hong Kong High-grade Glioma Registry from 2006 to 2023. Data of consecutive adult patients diagnosed with supratentorial glioblastoma and spinal metastasis were extracted and analyzed. Results: Among the 1342 patients with supratentorial glioblastoma, 15 were diagnosed to have spinal metastasis (1.1%). The median time to spinal metastasis from the initial diagnosis of glioblastoma was 38.7 weeks (IQR: 15.1–57.6). Multi-level spinal involvement was present in 60% (9/15) of patients. Neither the topographical location of the tumor in relation to the subventricular zone, extent of resection, occurrence of intraoperative ventricular entry, nor methylguanine methyltransferase (MGMT) promoter methylation status predicted the time to spinal metastasis. The median overall survival was 44.1 weeks (IQR: 29.9–80.2), and the median post-spinal metastasis survival was 12.6 weeks (IQR: 5.0–15.0). Two-thirds of patients received spinal radiotherapy, 26.7% had systemic therapy (chemotherapy, targeted therapy, and/or immunotherapy), and 13.3% underwent surgical spinal decompression. No significant survival improvement was observed among patients who received spinal radiotherapy (HR: 0.61; 95% CI: 0.17–2.23) or systemic therapy (HR: 0.94; 95% CI: 0.20–4.39). Conclusions: This case series illustrates the management practices and clinical course of glioblastoma patients with spinal metastasis. No treatment modality was proven to be superior. Treatment remains largely palliative and should be tailored on an individual basis.

Recurrence is a major complication of some meningiomas. Although there were many studies on biomarkers associated with higher grades or increased aggressiveness, few studies specifically examined longitudinal samples of primary meningiomas and recurrences from the same patients for molecular life history. We studied 99 primary and recurrent meningiomas from 42 patients by FISH for 22q, 1q, 1p, 3p, 5q, 6q, 10p, 10q, 14q, 18q, CDKN2A/B homozygous deletion, ALT (Alternative Lengthening of Telomere), TERT re‐arrangement, targeted sequencing and TERTp sequencing. Although NF2 mutation and 22q were well known to be aetiological events in meningiomas, we found that in these paired meningiomas, combining the two events resulted in an NF2/22q group (57 tumors from 25 patients) which were almost mutually exclusive with those cases without these two changes (42 tumors from 17 patients) for NF2/22q. No other molecular changes were totally unique to NF2/22q or non‐NF2/22q tumors. For molecular evolution, NF2/22q meningiomas had higher cytogenetic abnormalities than non‐NF2/22q meningiomas (p = 0.003). Most of the cytogenetic changes in NF2/22q meningiomas were present from the outset whereas for non‐NF2/22q meningiomas, cytogenetic events were uncommon in the primary tumors and most were acquired in recurrences. For non‐NF2/22q tumors, CDKN2A/B homozygous deletion, 1q gain, 18p loss, 3p loss, and ALT were preferentially found in recurrences. Mutations were largely conserved between primary and recurrent tumors. Phylogenetic trees showed 11/11 patients with multiple recurrent tumors had a conserved evolutionary pattern. We conclude that for molecular life history, NF2 and 22q should be regarded as a group. NF2/22q recurring meningiomas showed more cytogenetic abnormalities in the primary tumors, whereas non‐NF2/22q meningiomas showed CDKN2A/B deletion and other cytogenetic abnormalities and ALT at recurrences. Although chromosome 1p loss is a known poor prognostic marker in meningiomas, it was also associated with a shorter TBR (time between resection) in this cohort (p = 0.002).

Hypermutation and malignant transformation are potential complications arising from temozolomide treatment of IDH‐mutant gliomas. However, the natural history of IDH‐mutant low‐grade gliomas without temozolomide treatment is actually under‐studied. We retrieved retrospectively from our hospitals paired tumors from 19 patients with IDH‐mutant, 1p19q non‐codeleted Grade 2 astrocytomas where no interim adjuvant treatment with either temozolomide or radiotherapy was given between primary resections and first recurrences. Tissues from multiple recurrences were available from two patients and radiotherapy but not temozolomide was given before the last specimens were resected. We studied the natural molecular history of these low‐grade IDH‐mutant astrocytomas without pressure of temozolomide with DNA methylation profiling and copy number variation (CNV) analyses, targeted DNA sequencing, TERTp sequencing, FISH for ALT and selected biomarkers. Recurrences were mostly higher grades (15/19 patients) and characterized by new CNVs not present in the primary tumors (17/19 cases). Few novel mutations were identified in recurrences. Tumors from 17/19 (89.5%) patients showed either CDKN2A homozygous deletion, MYC or PDGFRA focal and non‐focal gains at recurrences. There was no case of hypermutation. Phylogenetic trees constructed for tumors for the two patients with multiple recurrences suggested a lack of subclone development in their evolution when under no pressure from temozolomide. In summary, our studies demonstrated, in contrast to the phenomenon of temozolomide‐induced hypermutation, IDH‐mutant, 1p19q non‐codeleted Grade 2 astrocytomas which had not been treated by temozolomide, acquired new CNVs at tumor recurrences. These findings improve our understanding of the molecular life history of IDH‐mutant astrocytomas. In this study, the natural molecular history of matched primary and recurrent tumors of 19 patients with IDH‐mutant, 1p19q non‐codeleted astrocytomas without pressure of temozolomide or radiotherapy was studied. Samples were examined for DNA methylation profiling and copy number variations, gene mutations and ALT. Recurrences were characterized by new CNVs not present in the primary tumors. Few novel mutations were identified in recurrences. CDKN2A homozygous deletion, MYC or PDGFRA focal and non‐focal gain were found at recurrences. Our findings improve the understanding of the molecular life history of IDH‐mutant astrocytomas.