The circadian clock is disrupted in pancreatic cancer.

Disruption of the circadian clock is linked to cancer development and progression. Establishing this connection has proven beneficial for understanding cancer pathogenesis, determining prognosis, and uncovering novel therapeutic targets. However, barriers to characterizing the circadian clock in human pancreas and human pancreatic cancer-one of the deadliest malignancies-have hindered an appreciation of its role in this cancer. Here, we employed normalized coefficient of variation (nCV) and clock correlation analysis in human population-level data to determine the functioning of the circadian clock in pancreas cancer and adjacent normal tissue. We found a substantially attenuated clock in the pancreatic cancer tissue. Then we exploited our existing mouse pancreatic transcriptome data to perform an analysis of the human normal and pancreas cancer samples using a machine learning method, cyclic ordering by periodic structure (CYCLOPS). Through CYCLOPS ordering, we confirmed the nCV and clock correlation findings of an intact circadian clock in normal pancreas with robust cycling of several core clock genes. However, in pancreas cancer, there was a loss of rhythmicity of many core clock genes with an inability to effectively order the cancer samples, providing substantive evidence of a dysregulated clock. The implications of clock disruption were further assessed with a Bmal1 knockout pancreas cancer model, which revealed that an arrhythmic clock caused accelerated cancer growth and worse survival, accompanied by chemoresistance and enrichment of key cancer-related pathways. These findings provide strong evidence for clock disruption in human pancreas cancer and demonstrate a link between circadian disruption and pancreas cancer progression.

Umpolung Flow Chemistry for the Synthesis of a 3-Oxo-3H-spiro[benzofuran-2,4'-piperidine] Building Block.

An efficient and scalable route to tert-butyl 3-oxo-3H-spiro[benzofuran-2,4'-piperidine]-1'-carboxylate, a central prochiral intermediate in the synthesis of SHP2 inhibitor GDC-1971 (migoprotafib), was achieved. Preparation of the title compound from readily available 2-fluorobenzaldehyde included formation of a modified Katritzky benzotriazole hemiaminal, which, upon deprotonation by n-butyllithium, participated in umpolung reactivity via 1,2-addition to tert-butyl 4-oxopiperidine-1-carboxylate (N-Boc-4-piperidone). Most notably, this reaction was developed as a robust plug-flow process that could be executed on multiple kilograms without the need for pilot-scale reaction vessels operating at low cryogenic temperatures. Treatment of the resulting tetrahedral intermediate with oxalic acid resulted in collapse to the corresponding 4-(2-fluorobenzoyl)-4-hydroxypiperidine, which was isolated as a solid via crystallization. The synthesis concluded with an optimized intramolecular SNAr reaction and final crystallization to generate tert-butyl 3-oxo-3H-spiro[benzofuran-2,4'-piperidine]-1'-carboxylate as a stable, high-quality intermediate suitable for further functionalization toward GDC-1971.

Understanding futility in pancreaticoduodenectomy: Insights from a national cohort.

BACKGROUND AND OBJECTIVES: Pancreaticoduodenectomy (PD), the only surgical option for right-sided pancreatic ductal adenocarcinoma (PDAC), carries significant morbidity. Not all patients may be deriving a survival benefit from this operation. We sought to identify the rate of futile PD and its associated factors in a large national cohort. METHODS: We performed a retrospective analysis using the National Cancer Database (2004-2020), including all patients who underwent PD for non-metastatic PDAC. The primary outcome was operative futility, which was defined as death within 12 months of diagnosis despite PD. Multivariable regression was used to identify factors associated with futility. We performed a subgroup analysis on patients who received neoadjuvant systemic therapy. RESULTS: Data from 66 326 patients were analyzed, and 16 772 (25.3%) underwent PD that met criteria for futility. Macroscopically positive margins (odds ratio [OR]: 2.87; 95% confidence interval [CI]: 2.36-3.48), poor tumor differentiation (OR: 2.44; 95% CI: 2.25-2.65), and N2 nodal stage (OR: 2.09; 95% CI: 1.98-2.20) were associated with the greatest odds of futility. Meanwhile, receipt of any systemic therapy (OR: 0.33; 95% CI: 0.31-0.34), receipt of any radiation (OR: 0.60; 95% CI: 0.57-0.63), and receipt of neoadjuvant systemic therapy (OR: 0.62; 95% CI: 0.57-0.66) were associated with the lowest odds of futility. In the neoadjuvant subgroup, a longer diagnosis-to-surgery interval was associated with lower odds of futility. CONCLUSION: PD was futile in about one quarter of patients. Futility was associated with higher age and worse tumor biology. Receipt of neoadjuvant therapy resulted in fewer futile operations.

Occipital Nocardia Abscess Presenting With Positive Visual Phenomenon and Quadrantanopsia.

ABSTRACT: A 74-year-old man with chronic obstructive pulmonary disease, glaucoma, and Stage IIIB squamous cell lung cancer experienced several minutes of flashing lights in his right visual hemifield, followed by onset of a right visual field defect. On examination, the patient had a right homonymous hemianopsia that was most dense inferiorly by confrontation testing. Emergent CT scan of the head revealed a 2.5 × 3 cm hypodensity in the left occipital lobe, which was interpreted as an acute stroke. Continuous EEG monitoring captured left posterior quadrant seizures that were temporally correlated to the positive visual phenomena. Subsequent MRI of the brain with and without contrast revealed a conglomerate of centrally necrotic and peripherally enhancing mass lesions. On biopsy, a thick purulent material was drained and Gram stain of the sample revealed gram-positive beaded rods, which speciated to Nocardia farcinica . The patient was treated with a six-week course of intravenous meropenem and a one-year course of oral trimethroprim-sulfamethoxazole. On follow-up, the patient experienced resolution of the right visual field deficit.

Rethinking Routine Intensive Care After Cytoreductive Surgery With Heated Intraperitoneal Chemotherapy: The Fiscal Argument.

BACKGROUND: Patients undergoing cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) are frequently admitted to the intensive care unit (ICU) for mitigation of potential complications, although ICU length of stay (LOS) is a significant driver of cost. This study asked whether a fiscal argument could be made for the selective avoidance of ICU admission after CRS/HIPEC. METHODS: Prospective data for select low-risk patients (e.g., lower peritoneal cancer index [PCI]) admitted to the intermediate care unit (IMC) instead of the ICU after CRS/HIPEC were matched with a historic cohort routinely admitted to the ICU. Cohort comparisons and the impact of the intervention on cost were assessed. RESULTS: The study matched 81 CRS/HIPEC procedures to form a cohort of 49 pre- and 15 post-intervention procedures for patients with similar disease burdens (mean PCI, 8 ± 6.7 vs. 7 ± 5.1). The pre-intervention patients stayed a median of 1 day longer in the ICU (1 day [IQR, 1-1 day] vs. 0 days [IQR, 0-0 days]) and had a longer LOS (8 days [IQR, 7-11 days] vs. 6 days [IQR, 5.5-9 days]). Complications and complication severity did not differ statistically. The median total hospital cost was lower after intervention ($30,845 [IQR, $30,181-$37,725] vs. $41,477 [IQR, $33,303-$51,838]), driven by decreased indirect fixed cost ($8984 [IQR, $8643-$11,286] vs. $14,314 [IQR, $12,206-$18,266]). In a weighted multiple variable linear regression analysis, the intervention was associated with a savings of $2208.68 per patient. CONCLUSIONS: Selective admission to the IMC after CRS/HIPEC was associated with $2208.68 in savings per patient without added risk. In this era of cost-conscious practice of medicine, these data highlight an opportunity to decrease cost by more than 5% for patients undergoing CRS/HIPEC.

Polymeric Nanoparticle-Based Vaccine Adjuvants and Delivery Vehicles.

As vaccine formulations have progressed from including live or attenuated strains of pathogenic components for enhanced safety, developing new adjuvants to more effectively generate adaptive immune responses has become necessary. In this context, polymeric nanoparticles have emerged as a promising platform with multiple advantages, including the dual capability of adjuvant and delivery vehicle, administration via multiple routes, induction of rapid and long-lived immunity, greater shelf-life at elevated temperatures, and enhanced patient compliance. This comprehensive review describes advances in nanoparticle-based vaccines (i.e., nanovaccines) with a particular focus on polymeric particles as adjuvants and delivery vehicles. Examples of the nanovaccine approach in respiratory infections, biodefense, and cancer are discussed.

Chronic jetlag-induced alterations in pancreatic diurnal gene expression.

Cell-autonomous circadian clocks exist in nearly every organ and function to maintain homeostasis through a complex series of transcriptional-translational feedback loops. The response of these peripheral clocks to external perturbations, such as chronic jetlag and shift work, has been extensively investigated. However, an evaluation of the effects of chronic jetlag on the mouse pancreatic transcriptome is still lacking. Herein, we report an evaluation of the diurnal variations encountered in the pancreatic transcriptome following exposure to an established chronic jetlag protocol. We found approximately 5.4% of the pancreatic transcriptome was rhythmic. Following chronic jetlag, we found the number of rhythmic transcripts decreased to approximately 3.6% of the transcriptome. Analysis of the core clock genes, which orchestrate circadian physiology, revealed that nearly all exhibited a shift in the timing of peak gene expression-known as a phase shift. Similarly, over 95% of the rhythmically expressed genes in the pancreatic transcriptome exhibited a phase shift, many of which were found to be important for metabolism. Evaluation of the genes involved in pancreatic exocrine secretion and insulin signaling revealed many pancreas-specific genes were also rhythmically expressed and several displayed a concomitant phase shift with chronic jetlag. Phase differences were found 9 days after normalization, indicating a persistent failure to reentrain to the new light-dark cycle. This study is the first to evaluate the endogenous pancreatic clock and rhythmic gene expression in whole pancreas over 48 h, and how the external perturbation of chronic jetlag affects the rhythmic expression of genes in the pancreatic transcriptome.

All-payer Spending on Common Hospital-based Services in California.

BACKGROUND: Hospital-based care accounts for one third of US health spending or over $1 trillion annually, yet a detailed all-payer assessment of what services contribute to this spending is not available. STUDY DESIGN: Cross-sectional and longitudinal evaluation of hospital financial statements from acute-care general hospitals in California between fiscal years 2007 and 2016. The amounts spent on 41 different revenue centers were included. The primary outcome was state-level and hospital-level spending for each revenue center including decomposing growth trends into changes in volume and prices. RESULTS: The analysis included 2941 annual financial statements from 331 hospitals. Between 2007 and 2016, total spending across all centers increased 66.6% from $43.7B to $72.9B. Five centers-surgery and recovery, drugs sold to patients, acute medical/surgical floor, the clinical laboratory, and emergency services-accounted for over 50% of total spending in 2016. Overall spending growths ranged from 1.1%/y (acute pediatrics) to 17.9%/y (observation). Other revenue centers with large increases in spending included emergency services (164.7%), clinics (on-site 114.5%, satellite 129.7%), anesthesia (119.6%), echocardiography (114.4%), and computed tomography (100.8%). Most services had volume growths within ±2%/y, although there were exceptions (eg, observation hours increased 10.0%/y). Prices grew fastest for echocardiograms (10.5%/y), cardiac catheterization (9.7%/y), therapeutic radiology (8.0%/y), and emergency visits (7.5%/y). In general, median prices for services in 2016 were larger than Medicare allowed amounts. CONCLUSIONS: Overall hospital-based spending increased 66.6% between 2007 and 2016 in California, but there was wide variation in spending growth across revenue centers. Understanding this variation-including the relative contributions of volumes and prices-can guide efforts to curb excessive health care spending and optimize resource dedication to current and future patient care needs.

Natural history and cost analysis of surgical bypass versus endoscopic stenting for the palliative management of malignant gastric outlet obstruction.

BACKGROUND: Malignant gastric outlet obstruction (GOO) is managed with palliative surgical bypass or endoscopic stenting. Limited data exist on differences in cost and outcomes. METHODS: Patients with malignant GOO undergoing palliative gastrojejunostomy (GJ) or endoscopic stent (ES) were identified between 2012 and 2015 using the MarketScan® Database. Median costs (payments) for the index procedure and 90-day readmissions and re-intervention were calculated. Frequency of treatment failure-defined as repeat surgery, stenting, or gastrostomy tube-was measured. RESULTS: A total of 327 patients were included: 193 underwent GJ and 134 underwent ES. Compared to GJ, stenting resulted in lower total median payments for the index hospitalization and procedure-related 90-day readmissions ($18,500 ES vs. $37,200 GJ, p = 0.032). For patients treated with ES, 25 (19%) required a re-intervention for treatment-failure, compared to 18 (9%) patients who underwent GJ (p = 0.010). On multivariable analysis, stenting remained significantly associated with need for secondary re-intervention compared to GJ (HR for ES 2.0 [1.1-3.8], p 0.028). CONCLUSION: In patients with malignant GOO, endoscopic stenting results in significant 90-day cost saving, however was associated with twice the rate of secondary intervention. The decision for surgical bypass versus endoscopic stenting should consider patient prognosis, anticipated cost, and likelihood of needing re-intervention.

Smoking and gastrointestinal cancer patients-is smoking cessation an attainable goal?

BACKGROUND AND OBJECTIVES: Negative consequences of tobacco use during cancer treatment are well-documented but more in-depth, patient-level data are needed to understand patient beliefs about continued smoking (vs cessation) during gastrointestinal (GI) cancer treatment. METHODS: We conducted semi-structured interviews with 10 patients who were active smokers being treated for GI cancers and 5 caregivers of such patients. All interviews were audio-recorded, transcribed verbatim, and uploaded to NVivo. We consensus coded data inductively using conventional content analysis and iteratively developed our codebook. We developed data matrices to categorize the themes regarding patient perspectives on smoking as well as presumed barriers to smoking cessation during active therapy. RESULTS: Our interviews revealed three consistent themes: (a) Smoking cessation is not necessarily desired by many patients who have received a cancer diagnosis; (b) Failure in past quit attempts may lead to feelings of hopeless about future attempts, especially during cancer treatment; (c) Patients perceived little to no access to smoking cessation treatment at the time of their cancer diagnosis. CONCLUSIONS: Well-designed systemic changes that promote the positive and efficacious effects of quitting smoking during cancer treatment, and that provide barrier-free access to such treatments may be helpful in promoting tobacco-free behavior during cancer treatment.

Role of radiation therapy for retroperitoneal sarcomas: An eight-institution study from the US Sarcoma Collaborative.

BACKGROUND: The use of radiation therapy in the treatment of retroperitoneal sarcomas has increased in recent years. Its impact on survival and recurrence is unclear. METHODS: A retrospective propensity score matched (PSM) analysis of patients with primary retroperitoneal soft tissue sarcomas, who underwent resection from 2000 to 2016 at eight institutions of the US Sarcoma Collaborative, was performed. Patients with metastatic disease, desmoid tumors, and palliative resections were excluded. RESULTS: Total 425 patients were included, 56 in the neoadjuvant radiation group (neo-RT), 75 in the adjuvant radiation group (adj-RT), and 294 in the no radiotherapy group (no-RT). Median age was 59.5 years, 186 (43.8%) were male with a median follow up of 31.4 months. R0 and R1 resection was achieved in 253 (61.1%) and 143 (34.5%), respectively. Overall 1:1 match of 46 adj-RT and 59 neo-RT patients was performed using histology, sex, age, race, functional status, tumor size, grade, resection status, and chemotherapy. Unadjusted recurrence-free survival (RFS) was 35.9 months (no-RT) vs 33.5 months (neo-RT) and 27.2 months (adj-RT), P = .43 and P = .84, respectively. In the PSM, RFS was 17.6 months (no-RT) vs 33.9 months (neo-RT), P = .28 and 19 months (no-RT) vs 27.2 months (adj-RT), P = .1. CONCLUSIONS: Use of radiotherapy, both in adjuvent or neoadjuvent setting, was not associated with improved survival or reduced recurrence rate.

Analysis of 90-day cost for open versus minimally invasive distal pancreatectomy.

BACKGROUND: Minimally invasive distal pancreatectomy (MIDP) is associated with improved peri-operative outcomes compared to the open approach, though cost-effectiveness of MIDP remains unclear. METHODS: Patients with pancreatic tumors undergoing open (ODP), robotic (RDP), or laparoscopic distal pancreatectomy (LDP) between 2012-2014 were identified through the Truven Health MarketScan® Database. Median costs (payments) for the index operation and 90-day readmissions were calculated. Multivariable regression was used to predict associations with log 90-day payments. RESULTS: 693 patients underwent ODP, 146 underwent LDP, and 53 RDP. Compared to ODP, LDP and RDP resulted in shorter median length of stay (6 d. ODP vs. 5 d. RDP vs. 4 d. LDP, p<0.01) and lower median payments ($38,350 ODP vs. $34,870 RDP vs. $32,148 LDP, p<0.01) during the index hospitalization. Total median 90-day payments remained significantly lower for both minimally invasive approaches ($40,549 ODP vs. $35,160 RDP vs. $32,797 LDP, p<0.01). On multivariable analysis, LDP and RDP resulted in 90-day cost savings of 21% and 25% relative to ODP, equating to an amount of $8,500-$10,000. CONCLUSION: MIDP is associated with >$8,500 in lower cost compared to the open approach. Quality improvement initiatives in DP should ensure that lack of training and technical skill are not barriers to MIDP.

The Impact of Hospital Neoadjuvant Therapy Utilization on Survival Outcomes for Pancreatic Cancer.

BACKGROUND: Many surgeons advocate the use of neoadjuvant treatment for resectable pancreatic cancer, however little is known about variation in the utilization of neoadjuvant therapy (NAT) at the hospital level. METHODS: The National Cancer Data Base was used to identify patients undergoing resection for pancreatic cancer between 2006 and 2014 at high-volume centers. Hospitals were grouped by NAT utilization using standard deviations (SD) from the mean as follows: high neoadjuvant utilizers (> 2 SDs above the mean, > 40% of patients receiving NAT); medium-high (1-2 SDs, 27-40%), medium (0-1 SD, 14-26%); or low (- 1.1 to 0 SDs, < 14%). Overall survival (OS) was compared across NAT utilization groups. RESULTS: Among 107 high-volume centers, 20,119 patients underwent resection. The proportion of patients receiving NAT varied widely among hospitals, ranging from 0 to 74%, with only five centers using NAT in > 40% of patients. These five hospitals had the longest median OS at 28.9 months, compared with 21.1 months for low neoadjuvant utilizers (p < 0.001). On multivariable analysis, high and medium-high NAT utilization predicted improved OS, with a hazard ratio (HR) of 0.68 (95% confidence interval [CI] 0.56-0.83, p < 0.001) and 0.80 (95% CI 0.68-0.95, p = 0.010), respectively, compared with low utilizers. After excluding patients who underwent NAT, there remained an association of improved OS with high NAT utilization (HR 0.74, 95% CI 0.60-0.93, p = 0.009). CONCLUSION: High-volume hospitals that more commonly utilize NAT demonstrated longer survival for all patients treated at those centers. In addition to altering patient selection for surgery, high neoadjuvant utilization may be a marker of institutional factors that contribute to improved outcomes.

Regret in Surgical Decision Making: A Systematic Review of Patient and Physician Perspectives.

OBJECTIVE: Regret is a powerful motivating factor in medical decision making among patients and surgeons. Regret can be particularly important for surgical decisions, which often carry significant risk and may have uncertain outcomes. We performed a systematic review of the literature focused on patient and physician regret in the surgical setting. METHODS: A search of the English literature between 1986 and 2016 that examined patient and physician self-reported decisional regret was carried out using the MEDLINE/PubMed and Web of Science databases. Clinical studies performed in patients and physicians participating in elective surgical treatment were included. RESULTS: Of 889 studies identified, 73 patient studies and 6 physician studies met inclusion criteria. Among the 73 patient studies, 57.5% examined patients with a cancer diagnosis, with breast (26.0%) and prostate (28.8%) cancers being most common. Interestingly, self-reported patient regret was relatively uncommon with an average prevalence across studies of 14.4%. Factors most often associated with regret included type of surgery, disease-specific quality of life, and shared decision making. Only 6 studies were identified that focused on physician regret; 2 pertained to surgical decision making. These studies primarily measured regret of omission and commission using hypothetical case scenarios and used the results to develop decision curve analysis tools. CONCLUSION: Self-reported decisional regret was present in about 1 in 7 surgical patients. Factors associated with regret were both patient- and procedure related. While most studies focused on patient regret, little data exist on how physician regret affects shared decision making.

The Aryl Hydrocarbon Receptor is a Repressor of Inflammation-associated Colorectal Tumorigenesis in Mouse.

OBJECTIVE: To determine the role of the aryl hydrocarbon receptor (AHR) in colitis-associated colorectal tumorigenesis. BACKGROUND: Colorectal cancer (CRC) is the third most commonly diagnosed cancer in United States. Chronic intestinal inflammation increases the risk for the development of CRC. We investigated the involvement of AHR, a ligand-activated transcriptional regulator, in colitis-associated colorectal tumorigenesis. METHODS: We used a mouse model of colitis-associated colorectal tumorigenesis that employs treatment with azoxymethane and dextran sodium sulfate. We examined the role of AHR using both an Ahr-deletion mouse model (Ahr) and treatment with the AHR pro-agonist indole-3-carbinol (I3C). Incidence, multiplicity, and location of tumors were visually counted. Tumors were defined as neoplasms. Intestinal inflammation was assessed by quantitative PCR for proinflammatory markers and colon length. Data were evaluated and compared using GraphPad Prism software (version 6, La Jolla, CA). RESULTS: Tumor incidence was increased 32% in Ahr null mice and tumor multiplicity was approximately increased 3-fold compared with wild-type mice (2.4 vs 7; P < 0.05). Furthermore, tumor multiplicity was reduced 92% by treatment of I3C in wild-type mice, whereas the suppressor effect of I3C was not observed in Ahr null mice (P < 0.05). CONCLUSIONS: We found that AHR plays a protective role in colitis-associated colorectal tumorigenesis. This conclusion is based on the observations that Ahr null mice showed increased number of colorectal tumors, and mice treated with I3C exhibited fewer tumors. This study supports the use of AHR agonists such as I3C as a chemopreventive therapy for IBD-associated CRC in human patients.

Management of choledochal cysts.

PURPOSE OF REVIEW: Historically, surgical treatment of choledochal cyst consisted of cyst enterostomy. However, incomplete cyst excision can result in recurrent symptoms and malignant transformation within the cyst remnant. Accordingly, management of choledochal cyst now includes complete cyst excision whenever possible. We provide a review detailing the up to date management of choledochal cysts. We describe choledochal cyst-type specific surgical approaches, the impact of minimally invasive surgery in choledochal cyst therapy, and long-term sequelae of choledochal cyst management. RECENT FINDINGS: Treatment of choledochal cyst aims to avoid the numerous hepatic, pancreatic, or biliary complications that may occur. More recently, minimally invasive approaches are being used for the treatment of choledochal cyst with acceptable morbidity and mortality. Moreover, long-term follow up of choledochal cyst patients after resection has demonstrated that although the risk of biliary malignancy is significantly decreased after choledochal cyst resection, these patients may remain at a slightly increased risk of biliary malignancy even after excision. SUMMARY: Management of choledochal cyst and the operative conduct will depend upon the patient comorbidities and choledochal cyst subtype. However, given the complex nature of choledochal cyst and limited experience of most centers, these patients should be evaluated and treated at high-volume hepatopancreaticobiliary centers familiar with management of choledochal cyst.

Synthesis and characterization of proteoglycan-mimetic graft copolymers with tunable glycosaminoglycan density.

Proteoglycans (PGs) are important glycosylated proteins found on the cell surface and in the extracellular matrix. They are made up of a core protein with glycosaminoglycan (GAG) side chains. Variations in composition and number of GAG side chains lead to a vast array of PG sizes and functions. Here we present a method for the synthesis of proteoglycan-mimetic graft copolymers (or neoproteoglycans) with tunable GAG side-chain composition. This is done using three different GAGs: hyaluronan, chondroitin sulfate, and heparin. Hyaluronan is functionalized with a hydrazide-presenting linker. Either chondroitin sulfate or heparin is grafted by the reducing end on to the hyaluronan backbone through reductive amination. PG mimics with heparin or chondroitin sulfate side chains and four different ratios of GAG side chain result in graft copolymers with a wide range of sizes. The chemistry is confirmed through attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and (1)H NMR. Effective hydrodynamic diameter and zeta potential are determined using dynamic light scattering and electrophoretic mobility measurements. Graft copolymers were tested for their ability to bind and deliver basic fibroblast growth factor (FGF-2) to mesenchymal stem cells (MSCs). The chondroitin sulfate-containing graft copolymers successfully deliver FGF-2 to cells from surfaces. The lowest graft density of heparin-containing PG mimic also performs well with respect to growth factor delivery from a surface. This new method for preparation of GAG-based graft copolymers enables a wide range of graft density, and can be used to explore applications of PG mimics as new biomaterials with tunable biochemical and biomechanical functions.

Specific and comprehensive genetic targeting reveals brain-wide distribution and synaptic input patterns of GABAergic axo-axonic interneurons.

Axo-axonic cells (AACs), also called chandelier cells (ChCs) in the cerebral cortex, are the most distinctive type of GABAergic interneurons described in the neocortex, hippocampus, and basolateral amygdala (BLA). AACs selectively innervate glutamatergic projection neurons (PNs) at their axon initial segment (AIS), thus may exert decisive control over PN spiking and regulate PN functional ensembles. However, the brain-wide distribution, synaptic connectivity, and circuit function of AACs remains poorly understood, largely due to the lack of specific and reliable experimental tools. Here, we have established an intersectional genetic strategy that achieves specific and comprehensive targeting of AACs throughout the mouse brain based on their lineage (Nkx2.1) and molecular (Unc5b, Pthlh) markers. We discovered that AACs are deployed across essentially all the pallium-derived brain structures, including not only the dorsal pallium-derived neocortex and medial pallium-derived hippocampal formation, but also the lateral pallium-derived claustrum-insular complex, and the ventral pallium-derived extended amygdaloid complex and olfactory centers. AACs are also abundant in anterior olfactory nucleus, taenia tecta and lateral septum. AACs show characteristic variations in density across neocortical areas and layers and across subregions of the hippocampal formation. Neocortical AACs comprise multiple laminar subtypes with distinct dendritic and axonal arborization patterns. Retrograde monosynaptic tracing from AACs across neocortical, hippocampal and BLA regions reveal shared as well as distinct patterns of synaptic input. Specific and comprehensive targeting of AACs facilitates the study of their developmental genetic program and circuit function across brain structures, providing a ground truth platform for understanding the conservation and variation of a bona fide cell type across brain regions and species.

Specific and comprehensive genetic targeting reveals brain-wide distribution and synaptic input patterns of GABAergic axo-axonic interneurons.

Axo-axonic cells (AACs), also called chandelier cells (ChCs) in the cerebral cortex, are the most distinctive type of GABAergic interneurons described in the neocortex, hippocampus, and basolateral amygdala (BLA). AACs selectively innervate glutamatergic projection neurons (PNs) at their axon initial segment (AIS), thus may exert decisive control over PN spiking and regulate PN functional ensembles. However, the brain-wide distribution, synaptic connectivity, and circuit function of AACs remain poorly understood, largely due to the lack of specific and reliable experimental tools. Here, we have established an intersectional genetic strategy that achieves specific and comprehensive targeting of AACs throughout the mouse brain based on their lineage (Nkx2.1) and molecular (Unc5b, Pthlh) markers. We discovered that AACs are deployed across essentially all the pallium-derived brain structures, including not only the dorsal pallium-derived neocortex and medial pallium-derived hippocampal formation, but also the lateral pallium-derived claustrum-insular complex, and the ventral pallium-derived extended amygdaloid complex and olfactory centers. AACs are also abundant in anterior olfactory nucleus, taenia tecta, and lateral septum. AACs show characteristic variations in density across neocortical areas and layers and across subregions of the hippocampal formation. Neocortical AACs comprise multiple laminar subtypes with distinct dendritic and axonal arborization patterns. Retrograde monosynaptic tracing from AACs across neocortical, hippocampal, and BLA regions reveal shared as well as distinct patterns of synaptic input. Specific and comprehensive targeting of AACs facilitates the study of their developmental genetic program and circuit function across brain structures, providing a ground truth platform for understanding the conservation and variation of a bona fide cell type across brain regions and species.

Whether we are memorising facts or reacting to a loud noise, nerve cells in different brain areas must be able to communicate with one another through precise, meaningful signals. Specialized nerve cells known as interneurons act as "traffic lights" to precisely regulate when and where this information flows in neural circuits. Axo-axonic cells are a rare type of inhibitory interneuron that are thought to be particularly important for controlling the passage of information between different groups of excitatory neurons. This is because they only connect to one key part of their target cell ­ the axon-initial segment ­ where the electrical signals needed for brain communication (known as action potentials) are initiated. Since axo-axonic cells are inhibitory interneurons, this connection effectively allows them to 'veto' the generation of these signals at their source. Although axo-axonic cells have been identified in three brain regions using traditional anatomical methods, there were no 'tags' readily available that can reliably identify them. Therefore, much about these cells remained unknown, including how widespread they are in the mammalian brain. To solve this problem, Raudales et al. investigated which genes are switched on in axo-axonic cells but not in other cells, identifying a unique molecular signature that could be used to mark, record, and manipulate these cells. Microscopy imaging of brain tissue from mice in which axo-axonic cells had been identified revealed that they are present in many more brain areas than previously thought, including nearly all regions of the broadly defined cerebral cortex and even the hypothalamus, which controls many innate behaviors. Axo-axonic cells were also 'wired up' differently, depending on where they were located; for example, those in brain areas associated with memory and emotions had wider-ranging input connections than other areas. The finding of Raudales et al. provide, for the first time, a method to directly track and manipulate axo-axonic cells in the brain. Since dysfunction in axo-axonic cells is also associated with neurological disorders like epilepsy and schizophrenia, gaining an insight into their distribution and connectivity could help to develop better treatments for these conditions.

Circadian disruption, clock genes, and metabolic health.

A growing body of research has identified circadian-rhythm disruption as a risk factor for metabolic health. However, the underlying biological basis remains complex, and complete molecular mechanisms are unknown. There is emerging evidence from animal and human research to suggest that the expression of core circadian genes, such as circadian locomotor output cycles kaput gene (CLOCK), brain and muscle ARNT-Like 1 gene (BMAL1), period (PER), and cyptochrome (CRY), and the consequent expression of hundreds of circadian output genes are integral to the regulation of cellular metabolism. These circadian mechanisms represent potential pathophysiological pathways linking circadian disruption to adverse metabolic health outcomes, including obesity, metabolic syndrome, and type 2 diabetes. Here, we aim to summarize select evidence from in vivo animal models and compare these results with epidemiologic research findings to advance understanding of existing foundational evidence and potential mechanistic links between circadian disruption and altered clock gene expression contributions to metabolic health-related pathologies. Findings have important implications for the treatment, prevention, and control of metabolic pathologies underlying leading causes of death and disability, including diabetes, cardiovascular disease, and cancer.