Leptin signalling altered in infantile nephropathic cystinosis-related bone disorder.

Background: The CTNS gene mutation causes infantile nephropathic cystinosis (INC). Patients with INC develop Fanconi syndrome and chronic kidney disease (CKD) with significant bone deformations. C57BL/6 Ctns mice are an animal model for studying INC.

Catastrophic implant failure after immediate loading of full arch implant prosthesis and its association with CPAP therapy: A case report.

Full arch implant-supported restorations are a common treatment modality for patients with a terminal dentition or an edentulous mouth. Several mechanical and biological factors that contribute to complications or failure are already extensively documented. Some patients receiving complex implant-based treatment plans also suffer from obstructive sleep apnea (OSA).

Preparation of Superactive Prolactin Receptor Antagonists.

Most breast cancer deaths are caused by malignant estrogen receptor-positive breast tumors that later recur as metastatic disease. Prolactin (PRL) has been documented as a factor promoting breast cancer development and metastasis. We therefore developed superactive prolactin receptor (PRLR) antagonists aimed at blocking PRL action.

Quantification of organic carbon and black carbon emissions, distribution, and carbon variation in diverse vegetative ecosystems across India.

Black Carbon (BC) and Organic Carbon (OC) are the principal chemical aerosol components generated during combustion, both of which play a key role in air pollution, human health and climate change. Several studies of OC and BC have been conducted over India to assess the contribution from household and fossil fuel-based sources; however, studies on their emissions and their contribution from forest and cropland fires are quite limited. To address this issue, as part of this research, we derived a vegetation burning-based inventory of BC and OC aerosols over India at a resolution of 250 m × 250 m.

A Leptin Receptor Antagonist Attenuates Adipose Tissue Browning and Muscle Wasting in Infantile Nephropathic Cystinosis-Associated Cachexia.

Mice lacking the functional cystinosin gene (), a model of infantile nephropathic cystinosis (INC), exhibit the cachexia phenotype with adipose tissue browning and muscle wasting. Elevated leptin signaling is an important cause of chronic kidney disease-associated cachexia. The pegylated leptin receptor antagonist (PLA) binds to but does not activate the leptin receptor.

COVID-19 Severity in Obesity: Leptin and Inflammatory Cytokine Interplay in the Link Between High Morbidity and Mortality.

Obesity is one of the foremost risk factors in coronavirus infection resulting in severe illness and mortality as the pandemic progresses. Obesity is a well-known predisposed chronic inflammatory condition. The dynamics of obesity and its impacts on immunity may change the disease severity of pneumonia, especially in acute respiratory distress syndrome, a primary cause of death from SARS-CoV-2 infection.

Multi-center real-world comparison of the fully automated Idylla™ microsatellite instability assay with routine molecular methods and immunohistochemistry on formalin-fixed paraffin-embedded tissue of colorectal cancer.

Microsatellite instability (MSI) is present in 15-20% of primary colorectal cancers. MSI status is assessed to detect Lynch syndrome, guide adjuvant chemotherapy, determine prognosis, and use as a companion test for checkpoint blockade inhibitors. Traditionally, MSI status is determined by immunohistochemistry or molecular methods.

Large-scale implementation of pooled RNA extraction and RT-PCR for SARS-CoV-2 detection.

Introduction: Testing for active SARS-CoV-2 infection is a fundamental tool in the public health measures taken to control the COVID-19 pandemic. Because of the overwhelming use of SARS-CoV-2 reverse transcription (RT)-PCR tests worldwide, the availability of test kits has become a major bottleneck and the need to increase testing throughput is rising. We aim to overcome these challenges by pooling samples together, and performing RNA extraction and RT-PCR in pools.

SIRT6 Promotes Hepatic Beta-Oxidation via Activation of PPARα.

The pro-longevity enzyme SIRT6 regulates various metabolic pathways. Gene expression analyses in SIRT6 heterozygotic mice identify significant decreases in PPARα signaling, known to regulate multiple metabolic pathways. SIRT6 binds PPARα and its response element within promoter regions and activates gene transcription.

Technical note: Effects of pegylation and route of administration on leptin kinetics in newborn lambs1.

Chronic energy insufficiency resulting from inadequate feed intake or increased nutrient demand reduces plasma leptin in ruminants. Treatment of energy-deficient ruminants with exogenous leptin has identified some physiological consequences of reduced plasma leptin, but their full complement remains unknown. Additional leptin-dependent responses could be identified by using strategies that interfere with leptin signaling such as administration of leptin mutants that act as competitive antagonists.

Pegylated Human Leptin D23L Mutant-Preparation and Biological Activity In Vitro and In Vivo in Male ob/ob Mice.

Recombinant monomeric human leptin (hLEP) and its D23L mutant were prepared in Escherichia coli and pegylated at their N-terminus using 20-kDa methoxy pegylated (PEG)-propionylaldehyde. As determined by both SDS-PAGE and size-exclusion chromatography, the pegylated proteins consisted of >90% monopegylated and <10% double-pegylated species. Circular dichroism spectra showed that their secondary structure, characteristic of all four α-helix bundle cytokines, was not affected by either the D23L mutation or pegylation.

New reagents for poultry research: preparation, purification, and in vitro evaluation of non-PEGylated and mono-PEGylated chicken prolactin.

Recombinant chicken prolactin (chPRL), expressed in Escherichia coli and purified as a monomer, was successfully PEGylated and purified to homogeneity as a mono-PEGylated protein (PEG-chPRL). Its biological activity was estimated by its ability to interact with human prolactin receptor extracellular domain (hPRLR-ECD) and stimulate PRLR-mediated proliferation in Nb2-11C cells. PEG-chPRL activity in a cell bioassay was 10-fold lower than that of non-PEGylated chPRL, but only 2-fold lower in a binding assay to hPRLR-ECD.

Preparation of biologically active monomeric recombinant zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss) recombinant growth hormones.

Fish growth hormones (GHs) play an important role in regulating growth, metabolism, reproduction, osmoregulation, and immunity and have thus garnered attention for their application in aquaculture. Zebrafish GH (zGH) cDNA or rainbow trout GH (rtGH) cDNA was cloned into the pMon3401 vector, expressed in MON105-competent Escherichia coli and purified to homogeneity. Their biological activity was evidenced by their ability to interact with ovine GH receptor extracellular domain and stimulate GH receptor-mediated proliferation in FDC-P1-3B9 cells stably transfected with rabbit GH receptor.

Hyperglycemia drives intestinal barrier dysfunction and risk for enteric infection.

Obesity, diabetes, and related manifestations are associated with an enhanced, but poorly understood, risk for mucosal infection and systemic inflammation. Here, we show in mouse models of obesity and diabetes that hyperglycemia drives intestinal barrier permeability, through GLUT2-dependent transcriptional reprogramming of intestinal epithelial cells and alteration of tight and adherence junction integrity. Consequently, hyperglycemia-mediated barrier disruption leads to systemic influx of microbial products and enhanced dissemination of enteric infection.

Preparation of Potent Leptin Receptor Antagonists and Their Therapeutic Use in Mouse Models of Uremic Cachexia and Kidney Fibrosis.

Leptin antagonists (L39A/D40A/F4lA mutants) of mouse, human, rat and ovine leptins were developed in our laboratory by rational mutagenesis, expressed in Escherichia coli, refolded and purified to homogeneity. Pegylation of these antagonists resulted in long-acting reagents suitable for in-vivo studies. Further selection of high-affinity leptin antagonists was achieved by random mutagenesis of the whole open reading frame followed by yeast- surface display; an additional mutation (D23L) increased their affinity toward leptin receptor 60-fold.

Novel reagents for human prolactin research: large-scale preparation and characterization of prolactin receptor extracellular domain, non-pegylated and pegylated prolactin and prolactin receptor antagonist.

To provide new tools for in vitro and in vivo prolactin (PRL) research, novel protocols for large-scale preparation of untagged human PRL (hPRL), a hPRL antagonist (del 1-9-G129R hPRL) that acts as a pure antagonist of hPRL in binding to hPRL receptor extracellular domain (hPRLR-ECD), and hPRLR-ECD are demonstrated. The interaction of del 1-9-G129R hPRL with hPRLR-ECD was demonstrated by competitive non-radioactive binding assay using biotinylated hPRL as the ligand and hPRLR-ECD as the receptor, by formation of stable 1:1 complexes with hPRLR-ECD under non-denaturing conditions using size-exclusion chromatography, and by surface plasmon resonance methodology. In all three types of experiments, the interaction of del 1-9-G129R hPRL was equal to that of unmodified hPRL.

Smoldering myocarditis following immune checkpoint blockade.

Background: Severe myocarditis associated with electrical conduction abnormalities and occasionally heart failure has been well documented following treatment with immune checkpoint blockade with an estimated incidence of less than 1%. However, the incidence, early detection, and management of less severe immune-related myocarditis are unknown since most immunotherapy trials have not included routine cardiac monitoring. Herein, we provide the first description of subclinical or smoldering myocarditis with minimal signs and symptoms following immune checkpoint blockade with a single dose of ipilimumab and nivolumab.

Persistent microbiome alterations modulate the rate of post-dieting weight regain.

In tackling the obesity pandemic, considerable efforts are devoted to the development of effective weight reduction strategies, yet many dieting individuals fail to maintain a long-term weight reduction, and instead undergo excessive weight regain cycles. The mechanisms driving recurrent post-dieting obesity remain largely elusive. Here we identify an intestinal microbiome signature that persists after successful dieting of obese mice and contributes to faster weight regain and metabolic aberrations upon re-exposure to obesity-promoting conditions.

Comparison of in vitro bioactivity of chicken prolactin and mammalian lactogenic hormones.

Recombinant chicken prolactin, expressed in Escherichia coli as an unfolded protein, was successfully refolded and purified to homogeneity as a monomeric protein. Its biological activity was evidenced by its ability to interact with rabbit prolactin receptor extracellular domain and stimulate prolactin receptor-mediated proliferation in three cell types possessing mammalian prolactin receptors. Chicken prolactin activity in those assays was 20-100-fold lower than that of mammalian lactogenic hormones, likely due to lower affinity for mammalian prolactin receptors and not to improper refolding, because in two homologous bioassays, chicken prolactin activity was equal to or higher than that of ovine prolactin and the CD spectra of chicken and human prolactin were almost identical.

Leptin resistance elicits depressive-like behaviors in rats.

There is a growing appreciation that the complications of obesity extend to the central nervous system (CNS) and include increased risk for development of neuropsychiatric co-morbidities such as depressive illness. The neurological consequences of obesity may develop as a continuum and involve a progression of pathological features which is initiated by leptin resistance. Leptin resistance is a hallmark feature of obesity, but it is unknown whether leptin resistance or blockage of leptin action is casually linked to the neurological changes which underlie depressive-like phenotypes.

Local Application of Leptin Antagonist Attenuates Angiotensin II-Induced Ascending Aortic Aneurysm and Cardiac Remodeling.

Background: Ascending thoracic aortic aneurysm (ATAA) is driven by angiotensin II (AngII) and contributes to the development of left ventricular (LV) remodeling through aortoventricular coupling. We previously showed that locally available leptin augments AngII-induced abdominal aortic aneurysms in apolipoprotein E-deficient mice. We hypothesized that locally synthesized leptin mediates AngII-induced ATAA.

Central Resistin/TLR4 Impairs Adiponectin Signaling, Contributing to Insulin and FGF21 Resistance.

Adiponectin, an insulin-sensitizing hormone, and resistin, known to promote insulin resistance, constitute a potential link between obesity and type 2 diabetes. In addition, fibroblast growth factor (FGF)21 has effects similar to those of adiponectin in regulating glucose and lipid metabolism and insulin sensitivity. However, the interplay between adiponectin, FGF21, and resistin signaling pathways during the onset of insulin resistance is unknown.

The complex role of SIRT6 in carcinogenesis.

SIRT6, a member of the mammalian sirtuins family, functions as a mono-ADP-ribosyl transferase and NAD(+)-dependent deacylase of both acetyl groups and long-chain fatty acyl groups. SIRT6 regulates diverse cellular functions such as transcription, genome stability, telomere integrity, DNA repair, inflammation and metabolic related diseases such as diabetes, obesity and cancer. In this review, we will discuss the implication of SIRT6 in the biology of cancer and the relevance to organism homeostasis and lifespan.

Insensitivity of well-conditioned mature sheep to central administration of a leptin receptor antagonist.

Ruminants remain productive during the energy insufficiency of late pregnancy or early lactation by evoking metabolic adaptations sparing available energy and nutrients (e.g. higher metabolic efficiency and induction of insulin resistance).

Identification of functional leptin receptors expressed in ventricular mitochondria.

Leptin is a 16 kDa pro-satiety peptide produced primarily not only by white adipocytes but also by numerous other tissues including the heart. Circulating leptin exerts its effect through specific receptors, although its principle actions are dependent on the activation of the long form of the leptin receptor, termed OBRb. As leptin is also produced within the cardiomyocyte, we hypothesized that the peptide can also exert effects by targeting intracellular sites.