Bioprinted 3D outer retina barrier uncovers RPE-dependent choroidal phenotype in advanced macular degeneration.

Age-related macular degeneration (AMD), a leading cause of blindness, initiates in the outer-blood-retina-barrier (oBRB) formed by the retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. The mechanisms of AMD initiation and progression remain poorly understood owing to the lack of physiologically relevant human oBRB models. To this end, we engineered a native-like three-dimensional (3D) oBRB tissue (3D-oBRB) by bioprinting endothelial cells, pericytes, and fibroblasts on the basal side of a biodegradable scaffold and establishing an RPE monolayer on top. In this 3D-oBRB model, a fully-polarized RPE monolayer provides barrier resistance, induces choriocapillaris fenestration, and supports the formation of Bruch's-membrane-like structure by inducing changes in gene expression in cells of the choroid. Complement activation in the 3D-oBRB triggers dry AMD phenotypes (including subRPE lipid-rich deposits called drusen and choriocapillaris degeneration), and HIF-α stabilization or STAT3 overactivation induce choriocapillaris neovascularization and type-I wet AMD phenotype. The 3D-oBRB provides a physiologically relevant model to studying RPE-choriocapillaris interactions under healthy and diseased conditions.

Pathological characterization of a novel mouse model expressing the PD-linked CHCHD2-T61I mutation.

Coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) is a mitochondrial protein that plays important roles in cristae structure, oxidative phosphorylation and apoptosis. Multiple mutations in CHCHD2 have been associated with Lewy body disorders (LBDs), such as Parkinson's disease (PD) and dementia with Lewy bodies, with the CHCHD2-T61I mutation being the most widely studied. However, at present, only CHCHD2 knockout or CHCHD2/CHCHD10 double knockout mouse models have been investigated. They do not recapitulate the pathology seen in patients with CHCHD2 mutations. We generated the first transgenic mouse model expressing the human PD-linked CHCHD2-T61I mutation driven by the mPrP promoter. We show that CHCHD2-T61I Tg mice exhibit perinuclear mitochondrial aggregates, neuroinflammation, and have impaired long-term synaptic plasticity associated with synaptic dysfunction. Dopaminergic neurodegeneration, a hallmark of PD, is also observed along with α-synuclein pathology. Significant motor dysfunction is seen with no changes in learning and memory at 1 year of age. A minor proportion of the CHCHD2-T61I Tg mice (~10%) show a severe motor phenotype consistent with human Pisa Syndrome, an atypical PD phenotype. Unbiased proteomics analysis reveals surprising increases in many insoluble proteins predominantly originating from mitochondria and perturbing multiple canonical biological pathways as assessed by ingenuity pathway analysis, including neurodegenerative disease-associated proteins such as tau, cofilin, SOD1 and DJ-1. Overall, CHCHD2-T61I Tg mice exhibit pathological and motor changes associated with LBDs, indicating that this model successfully captures phenotypes seen in human LBD patients with CHCHD2 mutations and demonstrates changes in neurodegenerative disease-associated proteins, which delineates relevant pathological pathways for further investigation.

Clinicopathologic features and outcomes of hepatic inflammatory pseudotumour (IPT) and hepatic IPT-like lesions.

AIMS: Hepatic inflammatory pseudotumours (IPTs) are nonneoplastic hepatic masses characterized by variably fibroblastic stroma and inflammatory infiltrate, hypothesized to arise as part of a response to infection or prior surgery. The aim of this study was to evaluate the clinicopathologic features and outcomes of biopsy-proven hepatic IPT as well as other cases with IPT-like histologic features. METHODS AND RESULTS: A database search at our institution identified cases with a pathologic diagnosis of hepatic IPT (n = 80) between 2000 and 2023. Histologic features (stromal quality, inflammatory cell components, granulomas, and necrosis) were evaluated. Past medical and surgical history, microbiologic studies, and outcomes were reviewed retrospectively. Patients frequently had a past medical history of malignancy (34%), biliary disease (15%), or prior intraabdominal surgery (24%), and often presented with multifocal hepatic lesions (36%). Variable inflammatory backgrounds were present, including histiocytic (36%), lymphoplasmacytic (34%), or neutrophilic (24%). Specific organisms were identified in 15% of cases, most commonly Klebsiella and Staphylococcus species. Most patients with available clinical follow-up demonstrated radiologic resolution and/or had repeat negative biopsy; a minority of patients (8%) were subsequently diagnosed with neoplastic hepatic lesions. No significant association was seen between histologic features and the subsequent clinical or pathologic diagnosis of hepatic neoplastic lesions. CONCLUSIONS: Hepatic IPT is a heterogeneous entity that can present in a variety of clinical scenarios and show a wide morphologic spectrum. These lesions often regress spontaneously or with antibiotics. A subset of cases with hepatic IPT-like histologic features were subsequently diagnosed with malignancy, emphasizing the need for continued follow-up and repeat biopsy depending on clinical and radiologic features.

TDP-43 and RNA form amyloid-like myo-granules in regenerating muscle.

A dominant histopathological feature in neuromuscular diseases, including amyotrophic lateral sclerosis and inclusion body myopathy, is cytoplasmic aggregation of the RNA-binding protein TDP-43. Although rare mutations in TARDBP-the gene that encodes TDP-43-that lead to protein misfolding often cause protein aggregation, most patients do not have any mutations in TARDBP. Therefore, aggregates of wild-type TDP-43 arise in most patients by an unknown mechanism. Here we show that TDP-43 is an essential protein for normal skeletal muscle formation that unexpectedly forms cytoplasmic, amyloid-like oligomeric assemblies, which we call myo-granules, during regeneration of skeletal muscle in mice and humans. Myo-granules bind to mRNAs that encode sarcomeric proteins and are cleared as myofibres mature. Although myo-granules occur during normal skeletal-muscle regeneration, myo-granules can seed TDP-43 amyloid fibrils in vitro and are increased in a mouse model of inclusion body myopathy. Therefore, increased assembly or decreased clearance of functionally normal myo-granules could be the source of cytoplasmic TDP-43 aggregates that commonly occur in neuromuscular disease.

Acute Non-ST Segment Elevation Myocardial Infarction Following Intravenous Injection of Sublingual Suboxone.

Non-ST segment elevation myocardial infarction (NSTEMI) is a relatively unknown complication of injecting sublingual Suboxone (buprenorphine/naloxone). Buprenorphine/naloxone should be taken as a sublingual tablet or a buccal film and not injected, so its effects from this mode of administration are not well known. While the differential diagnosis for chest pain is very broad, many practitioners do not associate chest pain with the use of buprenorphine/naloxone. We recommend considering serial electrocardiograms (ECGs) and high-sensitivity troponins for a patient who presents with chest pain after buprenorphine/naloxone use.

Use of orcein as an adjunct stain in the evaluation of advanced liver fibrosis.

AIMS: Advanced liver fibrosis can regress following the elimination of causative injuries. Trichrome (TC) stain has traditionally been used to evaluate the degree of fibrosis in liver, although it is rarely helpful in assessing quality of fibrosis (i.e. progression and regression). Orcein (OR) stain highlights established elastic fibres, but its use in examining fibrosis is not well recognised. This study assessed the potential utility of comparing OR and TC staining patterns to evaluate the quality of fibrosis in various settings of advanced fibrosis. METHODS AND RESULTS: The haematoxylin and eosin and TC stains of 65 liver resection/explant specimens with advanced fibrosis caused by different elements were reviewed. Twenty-two cases were scored as progressive (P), 16 as indeterminate (I) and 27 as regressive (R) using TC stain based on the Beijing criteria. The OR stains confirmed 18 of 22 P cases. The remaining P cases showed either stable fibrosis or mixed P and R. Of the 27 R cases, 26 were supported by OR stain, with many showing thin perforated septa typically seen in adequately treated viral hepatitis cases. The 16 I cases showed a variety of OR staining patterns, which allowed for further subclassification than using TC stain alone. Viral hepatitis cases were enriched for regressive features (17 of 27). CONCLUSIONS: Our data demonstrated the utility of OR as an adjunctive stain to evaluate the changes in fibrosis in cases of cirrhosis.

Stereotactic body radiotherapy for spine metastases: a review of 24 Gy in 2 daily fractions.

PURPOSE: Stereotactic body radiotherapy (SBRT) has proven to be a highly effective treatment for selected patients with spinal metastases. Randomized evidence shows improvements in complete pain response rates and local control with lower retreatment rates favoring SBRT, compared to conventional external beam radiotherapy (cEBRT). While there are several reported dose-fractionation schemes for spine SBRT, 24 Gy in 2 fractions has emerged with Level 1 evidence providing an excellent balance between minimizing treatment toxicity while respecting patient convenience and financial strain. METHODS: We provide an overview of the 24 Gy in 2 SBRT fraction regimen for spine metastases, which was developed at the University of Toronto and tested in an international Phase 2/3 randomized controlled trial. RESULTS: The literature summarizing global experience with 24 Gy in 2 SBRT fractions suggests 1-year local control rates ranging from 83-93.9%, and 1-year rates of vertebral compression fracture ranging from 5.4-22%. Reirradiation of spine metastases that failed prior cEBRT is also feasible with 24 Gy in 2 fractions, and 1-year local control rates range from 72-86%. Post-operative spine SBRT data are limited but do support the use of 24 Gy in 2 fractions with reported 1-year local control rates ranging from 70-84%. Typically, the rates of plexopathy, radiculopathy and myositis are under 5% in those series reporting mature follow up, with no cases of radiation myelopathy (RM) reported in the de novo setting when the spinal cord avoidance structure is limited to 17 Gy in 2 fractions. However, re-irradiation RM has been observed following 2 fraction SBRT. More recently, 2-fraction dose escalation with 28 Gy, with a higher dose constraint to the critical neural tissues, has been reported suggesting improved rates of local control. This regimen may be important in those patients with radioresistant histologies, high grade epidural disease, and/or paraspinal disease. CONCLUSION: The dose-fractionation of 24 Gy in 2 fractions is well-supported by published literature and is an ideal starting point for centers looking to establish a spine SBRT program.

Increased histologic inflammation is an independent risk factor for nonconventional dysplasia in ulcerative colitis.

AIMS: Several types of nonconventional dysplasia have been described in inflammatory bowel disease. Hypermucinous, goblet cell-deficient, and crypt cell dysplasias are considered high-risk subtypes, as they often have molecular features of advanced neoplasia (e.g. aneuploidy) and are more frequently associated with advanced neoplasia than conventional dysplasia. This study investigated if increased colonic inflammation is a risk factor for nonconventional dysplasia. METHODS AND RESULTS: A cohort of 125 patients with ulcerative colitis (UC)-associated dysplasia were analyzed and compared with 50 control UC patients without a history of neoplasia. For each patient, all biopsies prior to the initial detection of dysplasia were scored using a 4-point inflammatory activity score. Both mean and maximum scores from all biopsies taken during each colonoscopy were derived. Inflammation burden was calculated by multiplying the average maximum score between each pair of surveillance episodes by length of surveillance interval in years. The average scores of all colonoscopies were used to calculate overall mean, maximum, and inflammation burden scores. In multivariate analyses, higher maximum (odds ratio [OR] 3.4) and inflammation burden (OR 4.2) scores were significantly associated with the detection of dysplasia (P < 0.05). Similarly, higher mean and maximum scores increased the odds of nonconventional dysplasia by 2.7 and 4.9, respectively (P < 0.05). There was a stronger association between these two scores and high-risk subtypes (ORs 4.0 and 7.5, respectively, P < 0.05). CONCLUSION: The risk of nonconventional dysplasia is significantly associated with increased colonic inflammation, which may contribute to its higher rates of aneuploidy and malignancy.

Telomerase regulation by the long non-coding RNA H19 in human acute promyelocytic leukemia cells.

BACKGROUND: Since tumor growth requires reactivation of telomerase (hTERT), this enzyme is a challenging target for drug development. Therefore, it is of great interest to identify telomerase expression and activity regulators. Retinoids are well-known inducers of granulocytic maturation associated with hTERT repression in acute promyelocytic leukemia (APL) blasts. In a maturation-resistant APL cell line, we have previously identified a new pathway of retinoid-induced hTERT transcriptional repression independent of differentiation. Furthermore, we reported the isolation of a cell variant resistant to this repression. Those cell lines could serve as unique tools to identify new telomerase regulators. METHODS: Using a microarray approach we identified the long non-coding RNA, H19 as a potential candidate playing a role in telomerase regulation. Expression of H19, hTERT, and hTR were examined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Telomerase activity was quantified by quantitative telomeric repeats amplification protocol (qTRAP). In vitro and in vivo assays were performed to investigate H19 function on telomerase expression and activity. RESULTS: We showed both in retinoid-treated cell lines and in APL patient cells an inverse relationship between the expression of H19 and the expression and activity of hTERT. Exploring the mechanistic link between H19 and hTERT regulation, we showed that H19 is able to impede telomerase function by disruption of the hTERT-hTR interaction. CONCLUSIONS: This study identifies a new way of telomerase regulation through H19's involvement and thereby reveals a new function for this long non-coding RNA that can be targeted for therapeutic purpose.

Global profiling of hnRNP A2/B1-RNA binding on chromatin highlights LncRNA interactions.

Long noncoding RNAs (lncRNAs) often carry out their functions through associations with adaptor proteins. We recently identified heterogeneous ribonucleoprotein (hnRNP) A2/B1 as an adaptor of the human HOTAIR lncRNA. hnRNP A2 and B1 are splice isoforms of the same gene. The spliced version of HOTAIR preferentially associates with the B1 isoform, which we hypothesize contributes to RNA-RNA matching between HOTAIR and transcripts of target genes in breast cancer. Here we used enhanced cross-linking immunoprecipitation (eCLIP) to map the direct interactions between A2/B1 and RNA in breast cancer cells. Despite differing by only twelve amino acids, the A2 and B1 splice isoforms associate preferentially with distinct populations of RNA in vivo. Through cellular fractionation experiments we characterize the pattern of RNA association in chromatin, nucleoplasm, and cytoplasm. We find that a majority of interactions occur on chromatin, even those that do not contribute to co-transcriptional splicing. A2/B1 binding site locations on multiple RNAs hint at a contribution to the regulation and function of lncRNAs. Surprisingly, the strongest A2/B1 binding site occurs in a retained intron of HOTAIR, which interrupts an RNA-RNA interaction hotspot. In vitro eCLIP experiments highlight additional exonic B1 binding sites in HOTAIR which also surround the RNA-RNA interaction hotspot. Interestingly, a version of HOTAIR with the intron retained is still capable of making RNA-RNA interactions in vitro through the hotspot region. Our data further characterize the multiple functions of a repurposed splicing factor with isoform-biased interactions, and highlight that the majority of these functions occur on chromatin-associated RNA.

The accessible chromatin landscape of the human genome.

DNase I hypersensitive sites (DHSs) are markers of regulatory DNA and have underpinned the discovery of all classes of cis-regulatory elements including enhancers, promoters, insulators, silencers and locus control regions. Here we present the first extensive map of human DHSs identified through genome-wide profiling in 125 diverse cell and tissue types. We identify ∼2.9 million DHSs that encompass virtually all known experimentally validated cis-regulatory sequences and expose a vast trove of novel elements, most with highly cell-selective regulation. Annotating these elements using ENCODE data reveals novel relationships between chromatin accessibility, transcription, DNA methylation and regulatory factor occupancy patterns. We connect ∼580,000 distal DHSs with their target promoters, revealing systematic pairing of different classes of distal DHSs and specific promoter types. Patterning of chromatin accessibility at many regulatory regions is organized with dozens to hundreds of co-activated elements, and the transcellular DNase I sensitivity pattern at a given region can predict cell-type-specific functional behaviours. The DHS landscape shows signatures of recent functional evolutionary constraint. However, the DHS compartment in pluripotent and immortalized cells exhibits higher mutation rates than that in highly differentiated cells, exposing an unexpected link between chromatin accessibility, proliferative potential and patterns of human variation.

cAMP-Dependent Protein Kinase A (PKA)-Mediated c-Myc Degradation Is Dependent on the Relative Proportion of PKA-I and PKA-II Isozymes.

The transcription factor c-Myc regulates numerous target genes that are important for multiple cellular processes such as cell growth and differentiation. It is commonly deregulated in leukemia. Acute promyelocytic leukemia (APL) is characterized by a blockade of granulocytic differentiation at the promyelocyte stage. Despite the great success of all-trans retinoic acid (ATRA)-based therapy, which results in a clinical remission by inducing promyelocyte maturation, a significant number of patients relapse due to the development of ATRA resistance. A significant role has been ascribed to the cAMP/cAMP-dependent protein kinase A (PKA) signaling pathway in retinoid treatment since PKA activation is able to restore differentiation in some ATRA-resistant cells and eradicate leukemia-initiating cells in vivo. In this study, using NB4 APL cell variants resistant to ATRA-induced differentiation, we reveal distinct functional roles of the two PKA isozymes, PKA type I (PKA-I) and PKA-type II (PKA-II), on the steady-state level of c-Myc protein, providing a likely mechanism by which cAMP-elevating agents can restore differentiation in ATRA maturation-resistant APL cells. Therefore, both the inhibition of c-Myc activity and the PKA-I/PKA-II ratio should be taken into account if cAMP-based therapy is considered in the clinical management of APL.

The roles of the RIIß linker and N-terminal cyclic nucleotide-binding domain in determining the unique structures of the type IIß protein kinase A: a small angle x-ray and neutron scattering study.

Protein kinase A (PKA) is ubiquitously expressed and is responsible for regulating many important cellular functions in response to changes in intracellular cAMP concentrations. The PKA holoenzyme is a tetramer (R2:C2), with a regulatory subunit homodimer (R2) that binds and inhibits two catalytic (C) subunits; binding of cAMP to the regulatory subunit homodimer causes activation of the catalytic subunits. Four different R subunit isoforms exist in mammalian cells, and these confer different structural features, subcellular localization, and biochemical properties upon the PKA holoenzymes they form. The holoenzyme containing RIIß is structurally unique in that the type IIß holoenzyme is much more compact than the free RIIß homodimer. We have used small angle x-ray scattering and small angle neutron scattering to study the solution structure and subunit organization of a holoenzyme containing an RIIß C-terminal deletion mutant (RIIß(1-280)), which is missing the C-terminal cAMP-binding domain to better understand the structural organization of the type IIß holoenzyme and the RIIß domains that contribute to stabilizing the holoenzyme conformation. Our results demonstrate that compaction of the type IIß holoenzyme does not require the C-terminal cAMP-binding domain but rather involves large structural rearrangements within the linker and N-terminal cyclic nucleotide-binding domain of the RIIß homodimer. The structural rearrangements are significantly greater than seen previously with RIIα and are likely to be important in mediating short range and long range interdomain and intersubunit interactions that uniquely regulate the activity of the type IIß isoform of PKA.

pH-dependent spectroscopy of tetracycline and its analogs.

Tetracyclines (TCs), broad spectrum antibiotics widely used in the prevention and treatment of infectious diseases, are amphoteric molecules containing several ionizable functional groups that exist predominantly as zwitterions at a given pH value. TCs are reported to undergo a wide variety of reactions at different pH values i.e. TCs form to anhydrotetracyclines at low pH, 4-epitetracyclines at pH 3-5 and isotetracyclines at high pH values. The pH-dependent absorbance and emission properties of tetracycline and its 10 analogs (4-epitetracycline, doxycyline, oxytetracycline, chlortetracycline, 4-epichlortetracycline, isochlortetracycline, methacycline, rolitetracycline, minocycline, and demeclocycline) were investigated and reported in this paper. The main focus of the study was on the pH dependent transformation of epichlortetracycline, chlortetracycline and isotetracycline at basic pH. Absorption, emission and time resolved spectroscopy were used to determine the behavior of the three TC derivatives at this condition. Increasing the buffer's ionic concentration leads to faster transformation to iCTC. A pH dependent transformation of CTC to iCTC was observed and the lifetimes of CTC and iCTC were determined to be 3.0 and 5.89 ns respectively. The distribution factor of CTC to iCTC at basic pH was also reported for the first time.

Necessity and impact of specialization of large foundation model for medical segmentation tasks.

BACKGROUND: Large foundation models, such as the Segment Anything Model (SAM), have shown remarkable performance in image segmentation tasks. However, the optimal approach to achieve true utility of these models for domain-specific applications, such as medical image segmentation, remains an open question. Recent studies have released a medical version of the foundation model MedSAM by training on vast medical data, who promised SOTA medical segmentation. Independent community inspection and dissection is needed. PURPOSE: Foundation models are developed for general purposes. On the other hand, stable delivery of reliable performance is key to clinical utility. This study aims at elucidating the potential advantage and limitations of landing the foundation models in clinical use by assessing the performance of off-the-shelf medical foundation model MedSAM for the segmentation of anatomical structures in pelvic MR images. We also explore the simple remedies by evaluating the dependency on prompting scheme. Finally, we demonstrate the need and performance gain of further specialized fine-tuning. METHODS: MedSAM and its lightweight version LiteMedSAM were evaluated out-of-the-box on a public MR dataset consisting of 589 pelvic images split 80:20 for training and testing. An nnU-Net model was trained from scratch to serve as a benchmark and to provide bounding box prompts for MedSAM. MedSAM was evaluated using different quality bounding boxes, those derived from ground truth labels, those derived from nnU-Net, and those derived from the former two but with 5-pixel isometric expansion. Lastly, LiteMedSAM was refined on the training set and reevaluated on this task. RESULTS: Out-of-the-box MedSAM and LiteMedSAM both performed poorly across the structure set, especially for disjoint or non-convex structures. Varying prompt with different bounding box inputs had minimal effect. For example, the mean Dice score and mean Hausdorff distances (in mm) for obturator internus using MedSAM and LiteMedSAM were {0.251 ± 0.110, 0.101 ± 0.079} and {34.142 ± 5.196, 33.688 ± 5.306}, respectively. Fine-tuning of LiteMedSAM led to significant performance gain, improving Dice score and Hausdorff distance for the obturator internus to 0.864 ± 0.123 and 5.022 ± 10.684, on par with nnU-Net with no significant difference in evaluation of most structures. All segmentation structures benefited significantly from specialized refinement, at varying improvement margin. CONCLUSION: While our study alludes to the potential of deep learning models like MedSAM and LiteMedSAM for medical segmentation, it highlights the need for specialized refinement and adjudication. Off-the-shelf use of such large foundation models is highly likely to be suboptimal, and specialized fine-tuning is often necessary to achieve clinical desired accuracy and stability.

Glutamine synthetase staining patterns in cirrhosis.

Advanced liver fibrosis can regress following the elimination of causative injuries. Glutamine synthetase (GS) immunohistochemical expression is normally in centrizonal perivenular hepatocytes but can be present in periportal hepatocytes in cases of regressed cirrhosis. This study identified periportal staining and investigated the spectrum of GS staining patterns seen in a range of cirrhotic livers with varying disease processes. The hematoxylin and eosin and GS-stained slides of 88 liver resection/explant specimens with advanced fibrosis cases by different causes were reviewed, and trichrome and orcein stains were used to classify cases as progressive, indeterminate, or regressive. Periportal GS staining was seen in 97% of regressive cases and 84% progressive or indeterminate cases. Liver resection specimens with periportal GS staining showed a variety of patterns, including predominantly perivenular, predominantly periseptal, and perinodular staining. The GS periseptal pattern is more common in regressed cirrhosis compared to progressive cases. The perinodular staining was seen in 16 cases resulting from various etiologies, including biliary atresia, steatotic liver disease, primary biliary cholangitis, and viral hepatitis, 75% of which demonstrated cholestasis. This study further subclassified GS staining patterns of "periportal" pattern in cirrhotic liver. Compared to orcein/trichrome staining, GS immunohistochemical staining is not as useful in distinguishing regressed cases from non-regressed cases.

Expanding the Spectrum of GLI1-rearranged Neoplasms of the Gastrointestinal Tract to Include Monophasic Keratin-positive Epithelial Neoplasms.

GLI1-altered tumors form a diverse group occurring in various anatomic locations. In the alimentary tract, the most established are gastroblastoma, a biphasic epithelial-mesenchymal neoplasm of the stomach, and plexiform fibromyxoma, a pure spindle cell neoplasm. The spectrum of GLI1-rearranged gastrointestinal tumors has recently expanded with reports of cases in other parts of the GI tract, some exhibiting gastroblastoma-like features and others being pure mesenchymal neoplasms. These tumors often display a nonspecific immunophenotype, with only CD56 and cyclin D1 expression being common. Biphasic GLI1-altered tumors show diffuse keratin positivity in the epithelial component only, and GLI1-altered mesenchymal tumors typically lack or show only focal keratin expression. This study details 2 GLI1-rearranged gastrointestinal tract tumors with diffuse keratin and CD56 expression, composed entirely of epithelial cells with a nested growth pattern and finely stippled monotonous nuclei, leading to an initial suspicion of neuroendocrine tumor in both cases, despite lack of synaptophysin and chromogranin expression. Diffuse strong nuclear cyclin D1 expression was seen in both cases, and conversely, strong cyclin D1 staining was only seen in 5.4% (4/74) of well-differentiated neuroendocrine tumors tested. These 2 GI tract neoplasms highlight a widened spectrum of GLI1-rearranged tumors, now including monophasic epithelial neoplasms with diffuse keratin expression.

Practice and principles of stereotactic body radiation therapy for spine and non-spine bone metastases.

Radiotherapy is the dominant treatment modality for painful spine and non-spine bone metastases (NSBM). Historically, this was achieved with conventional low dose external beam radiotherapy, however, stereotactic body radiotherapy (SBRT) is increasingly applied for these indications. Meta-analyses and randomized clinical trials have demonstrated improved pain response and more durable tumor control with SBRT for spine metastases. However, in the setting of NSBM, there is limited evidence supporting global adoption and large scale randomized clinical trials are in need. SBRT is technically demanding requiring careful consideration of organ at risk tolerance, and strict adherence to technical requirements including immobilization, simulation, contouring and image-guidance procedures. Additional considerations include follow up practices after SBRT, with appropriate imaging playing a critical role in response assessment. Finally, there is renewed research into promising new technologies that may further refine the use of SBRT in both spinal and NSBM in the years to come.

Single-cell genomics and regulatory networks for 388 human brains.

Single-cell genomics is a powerful tool for studying heterogeneous tissues such as the brain. Yet, little is understood about how genetic variants influence cell-level gene expression. Addressing this, we uniformly processed single-nuclei, multi-omics datasets into a resource comprising >2.8M nuclei from the prefrontal cortex across 388 individuals. For 28 cell types, we assessed population-level variation in expression and chromatin across gene families and drug targets. We identified >550K cell-type-specific regulatory elements and >1.4M single-cell expression-quantitative-trait loci, which we used to build cell-type regulatory and cell-to-cell communication networks. These networks manifest cellular changes in aging and neuropsychiatric disorders. We further constructed an integrative model accurately imputing single-cell expression and simulating perturbations; the model prioritized ~250 disease-risk genes and drug targets with associated cell types.