Insulin Infusion Is Linked to Increased NPPC Expression in Muscle and Plasma C-type Natriuretic Peptide in Male Dogs.

The purpose of this study was to assess insulin-stimulated gene expression in canine skeletal muscle with a particular focus on NPPC, the gene that encodes C-type natriuretic peptide, a key hormonal regulator of cardiometabolic function. Four conscious canines underwent hyperinsulinemic, euglycemic clamp studies. Skeletal muscle biopsy and arterial plasma samples were collected under basal and insulin-stimulated conditions. Bulk RNA sequencing of muscle tissue was performed to identify differentially expressed genes between these 2 steady-state conditions. Our results showed that NPPC was the most highly expressed gene in skeletal muscle in response to insulin infusion, rising 4-fold between basal and insulin-stimulated conditions. In support of our RNA sequencing data, we found that raising the plasma insulin concentration 15-fold above basal elicited a 2-fold (P = 0.0001) increase in arterial plasma concentrations of N-terminal prohormone C-type natriuretic peptide. Our data suggest that insulin may play a role in stimulating secretion of C-type natriuretic peptide by skeletal muscle. In this context, C-type natriuretic peptide may act in a paracrine manner to facilitate muscle-vascular bed crosstalk and potentiate insulin-mediated vasodilation. This could serve to enhance insulin and glucose delivery, particularly in the postprandial absorptive state.

Patient-Reported Outcome Measures in Colon and Rectal Surgery: A Systematic Review and Quality Assessment.

BACKGROUND: There is growing interest in using patient-reported outcome measures to support value-based care in colorectal surgery. To draw valid conclusions regarding patient-reported outcomes data, measures with robust measurement properties are required. OBJECTIVE: The purpose of this study was to assess the use and quality of patient-reported outcome measures in colorectal surgery. DATA SOURCES: Three major databases were searched for studies using patient-reported outcome measures in the context of colorectal surgery. STUDY SELECTION: Articles that used patient-reported outcome measures as outcome for colorectal surgical intervention in a comparative effectiveness analysis were included. Exclusion criteria included articles older than 11 years, non-English language, age <18 years, fewer than 40 patients, case reports, review articles, and studies without comparison. MAIN OUTCOME MEASURES: This was a quality assessment using a previously reported checklist of psychometric properties. RESULTS: From 2007 to 2018, 368 studies were deemed to meet inclusion criteria. These studies used 165 distinct patient-reported outcome measures. Thirty were used 5 or more times and were selected for quality assessment. Overall, the measures were generally high quality, with 21 (70%) scoring ≥14 on an 18-point scale. Notable weaknesses included management of missing data (14%) and description of literacy level (0%). LIMITATIONS: The study was limited by its use of original articles for quality assessment. Measures were selected for quality analysis based on frequency of use rather than other factors, such as impact of the article or number of patients in the study. CONCLUSIONS: Patient-reported outcome measures are widely used in colorectal research. There was a wide range of measures available, and many were used only once. The most frequently used measures are generally high quality, but a majority lack details on how to deal with missing data and information on literacy levels. As the use of patient-reported outcome measures to assess colorectal surgical intervention increases, researchers and practitioners need to become more knowledgeable about the measures available and their quality.

The kinetics of glucagon action on the liver during insulin-induced hypoglycemia.

Glucagon's effect on hepatic glucose production (HGP), under hyperglycemic conditions, is time dependent such that after an initial burst of HGP, it slowly wanes. It is not known whether this is also the case under hypoglycemic conditions, where an increase in HGP is essential. This question was addressed using adrenalectomized dogs to avoid the confounding effects of other counterregulatory hormones. During the study, infusions of epinephrine and cortisol were given to maintain basal levels. Somatostatin and insulin (800 µU·kg-1·min-1) were infused to induce hypoglycemia. After 30 min, glucagon was infused at a basal rate (1 ng·kg-1·min-1, baGGN group, n = 5 dogs) or a rate eightfold basal (8 ng·kg-1·min-1, hiGGN group, n = 5 dogs) for 4 h. Glucose was infused to match the arterial glucose levels between groups (≈50 mg/dL). Our data showed that glucagon has a biphasic effect on the liver despite hypoglycemia. Hyperglucagonemia stimulated a rapid, transient peak in HGP (4-fold basal production) over ~60 min, which was followed by a slow reduction in HGP to a rate 1.5-fold basal. During the last 2 h of the experiment, hiGGN stimulated glucose production at a rate fivefold greater than baGGN (2.5 vs. 0.5 mg·kg-1·min-1, respectively), indicating a sustained effect of the hormone. Of note, the hypoglycemia-induced rises in norepinephrine and glycerol were smaller in hiGGN compared with the baGGN group despite identical hypoglycemia. This finding suggests that there is reciprocity between glucagon and the sympathetic nervous system such that when glucagon is increased, the sympathetic nervous response to hypoglycemia is downregulated.

Assessing Hereditary Colorectal Cancer Referral Patterns to a Tertiary Care Center: A Novel Approach Using Geographic Information System Mapping.

BACKGROUND: Patients and their family members with hereditary colorectal cancer require longitudinal follow-up that is best achieved through a dedicated program with a registry. However, referrals for these conditions remain poor. Geographic information systems technology is a novel method to evaluate geographic variation in multiple realms but is being used more in health care. OBJECTIVE: The purpose of this study was to evaluate referral patterns with geographic information systems technology to better target efforts for improving overall referrals. We hypothesized that marked variation would exist as to the geospatial locations of referrals and that gastroenterologists would be the dominant referral source. DESIGN: This was a retrospective cross-sectional study. SETTINGS: The study was conducted at Vanderbilt University Medical Center. PATIENTS: The hereditary colorectal cancer registry was queried from June 2007 to August 2016 for demographics, distance to center, genetic mutations, and the specialty of the referring providers. Geospatial data on both patient and referring specialist were collected. MAIN OUTCOME MEASURES: We analyzed patient and referral data with geographic information systems technology to look for gaps and patterns. RESULTS: A total of 676 patients were entered into the registry during this period. Fifty-six percent were women, and the median age was 50 years (interquartile range, 42-60 y). The median distance from the center was 60 miles (interquartile range, 22-120 miles), and 31% carried an identified germline mutation. Gastroenterology represented the overall largest source of referrals and, when broken down by syndrome, they represented the top referral specialty for familial adenomatous polyposis. Surgeons were the largest referral source for Lynch syndrome. LIMITATIONS: The study was limited by covariates in the database. CONCLUSIONS: Our hereditary colorectal cancer registry serves a large geographic area, with the largest group of referrals coming from gastroenterologists. Performing this analysis with geographic information systems technology mapping allowed us to identify clustering of patients and providers throughout the region as well as gaps. This information will help to target outreach and distribution of educational materials for providers and their patients to increase registry enrollment. See Video Abstract at http://links.lww.com/DCR/A950.

Pharmacokinetics, Tissue Localization, Toxicity, and Treatment Efficacy in the First Small Animal (Rabbit) Model of Intra-Arterial Chemotherapy for Retinoblastoma.

Purpose: Current intra-arterial chemotherapy (IAC) drug regimens for retinoblastoma have ocular and vascular toxicities. No small-animal model of IAC exists to test drug efficacy and toxicity in vivo for IAC drug discovery. The purpose of this study was to develop a small-animal model of IAC and to analyze the ocular tissue penetration, distribution, pharmacokinetics, and treatment efficacy. Methods: Following selective ophthalmic artery (OA) catheterization, melphalan (0.4 to 1.2 mg/kg) was injected. For pharmacokinetic studies, rabbits were euthanized at 0.5, 1, 2, 4, or 6 hours following intra-OA infusion. Drug levels were determined in vitreous, retina, and blood by liquid chromatography tandem mass spectrometry. To assess toxicity, angiograms, photography, fluorescein angiography, and histopathology were performed. For in situ tissue drug distribution, matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) was performed. The tumor model was created by combined subretinal/intravitreal injection of human WERI-Rb1 retinoblastoma cells; the tumor was treated in vivo with intra-arterial melphalan or saline; and induction of tumor death was measured by cleaved caspase-3 activity. Results: OA was selectively catheterized for 79 of 79 (100%) eyes in 47 of 47 (100%) rabbits, and melphalan was delivered successfully in 31 of 31 (100%) eyes, without evidence of vascular occlusion or retinal damage. For treated eyes, maximum concentration (Cmax) in the retina was 4.95 µM and area under the curve (AUC0→∞) was 5.26 µM·h. Treated eye vitreous Cmax was 2.24 µM and AUC0→∞ was 4.19 µM·h. Vitreous Cmax for the treated eye was >100-fold higher than for the untreated eye (P = 0.01), and AUC0→∞ was ∼50-fold higher (P = 0.01). Histology-directed MALDI-IMS revealed highest drug localization within the retina. Peripheral blood Cmax was 1.04 µM and AUC0→∞ was 2.07 µM·h. Combined subretinal/intravitreal injection of human retinoblastoma cells led to intra-retinal tumors and subretinal/vitreous seeds, which could be effectively killed in vivo with intra-arterial melphalan. Conclusions: This first small-animal model of IAC has excellent vitreous and retinal tissue drug penetration, achieving levels sufficient to kill human retinoblastoma cells, facilitating future IAC drug discovery.

Patient-reported outcomes in liver transplant recipients with hepatocellular carcinoma.

BACKGROUND: The effect of awarding MELD exception points for hepatocellular carcinoma (HCC) on patient-reported outcomes (PROs) is unknown. We evaluated the physical and mental health-related quality of life (HRQOL) and symptoms of anxiety and depression in liver transplant recipients with HCC compared to patients without HCC. METHODS: The single-center sample measured PROs before and after transplant, which included 1521 multisurvey measurement points among 502 adults (67% male, 28% HCC, follow-up time: <1-131 months). Data were analyzed using multivariable mixed-effects models. RESULTS: Longitudinal PRO values did not differ between persons who received HCC exception points and those who did not have HCC. Patients with HCC who did not receive exception points had reduced physical HRQOL (P=.016), a late decline in mental HRQOL, and delayed reduction in anxiety (time-by-outcome interaction P<.050) compared to patients with HCC who received exception points. CONCLUSION: Transplant recipients who received HCC exception points had PROs that were comparable to those of patients without HCC, and reported better physical HRQOL and reduced symptoms of anxiety compared to patients with HCC who did not receive exception points. These analyses demonstrate the impact of HCC exception points on PROs, and may help inform policy regarding HCC exception point allocation.

First Implantation of Silicon Nanopore Membrane Hemofilters.

An implantable hemofilter for the treatment of kidney failure depends critically on the transport characteristics of the membrane and the biocompatibility of the membrane, cartridge, and blood conduits. A novel membrane with slit-shaped pores optimizes the trade-off between permeability and selectivity, enabling implanted therapy. Sustained (3-8) day function of an implanted parallel-plate hemofilter with minimal anticoagulation was achieved by considering biocompatibility at the subnanometer scale of chemical interactions and the millimeter scale of blood fluid dynamics. A total of 400 nm-thick polysilicon flat sheet membranes with 5-8 nm × 2 micron slit-shaped pores were surface-modified with polyethylene glycol. Hemofilter cartridge geometries were refined based on computational fluid dynamics models of blood flow. In an uncontrolled pilot study, silicon filters were implanted in six class A dogs. Cartridges were connected to the cardiovascular system by anastamoses to the aorta and inferior vena cava and filtrate was drained to collection pouches positioned in the peritoneum. Pain medicine and acetylsalicylic acid were administered twice daily until the hemofilters were harvested on postoperative days 3 (n = 2), 4 (n = 2), 5 (n = 1), and 8 (n = 1). No hemofilters were thrombosed. Animals treated for 5 and 8 days had microscopic fractures in the silicon nanopore membranes and 20-50 ml of transudative (albumin sieving coefficient θalb ~ 0.5 - 0.7) fluid in the collection pouches at the time of explant. Shorter experimental durations (3-4 days) resulted in filtration volumes similar to predictions based on mean arterial pressures and membrane hydraulic permeability and (θalb ~ 0.2 - 0.3), similar to preimplantation measurements. In conclusion, a detailed mechanistic and materials science attention to blood-material interactions allows implanted hemofilters to resist thrombosis. Additional testing is needed to determine optimal membrane characteristics and identify limiting factors in long-term implantation.