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Laser heterodyne measurements have been used to study the nonradiative energy loss of isolated rhodamine 6G molecules in methanol solutions with different potassium iodide quencher concentrations. Simultaneous measurement of both the relative fluorescent intensity and photothermal phase modulation induced by argon ion laser excitation allows absolute determination of both the quantum yield and the fraction of absorbed photo-energy converted to heat. At zero quencher concentration, their values were found to be 98.2% and 12%, respectively. [ABSTRACT FROM AUTHOR]

The transmembrane protein SLC22A17 [or the neutrophil gelatinase-associated lipocalin/lipocalin-2 (LCN2)/24p3 receptor] is an atypical member of the SLC22 family of organic anion and cation transporters: it does not carry typical substrates of SLC22 transporters but mediates receptor-mediated endocytosis (RME) of LCN2. One important task of the kidney is the prevention of urinary loss of proteins filtered by the glomerulus by bulk reabsorption of multiple ligands via megalin:cubilin:amnionless-mediated endocytosis in the proximal tubule (PT). Accordingly, overflow, glomerular, or PT damage, as in Fanconi syndrome, results in proteinuria. Strikingly, up to 20% of filtered proteins escape the PT under physiological conditions and are reabsorbed by the distal nephron. The renal distal tubule and collecting duct express SLC22A17, which mediates RME of filtered proteins that evade the PT but with limited capacity to prevent proteinuria under pathological conditions. The kidney also prevents excretion of filtered essential and nonessential transition metals, such as iron or cadmium, respectively, that are largely bound to proteins with high affinity, e.g., LCN2, transferrin, or metallothionein, or low affinity, e.g., microglobulins or albumin. Hence, increased uptake of transition metals may cause nephrotoxicity. Here, we assess the literature on SLC22A17 structure, topology, tissue distribution, regulation, and assumed functions, emphasizing renal SLC22A17, which has relevance for physiology, pathology, and nephrotoxicity due to the accumulation of proteins complexed with transition metals, e.g., cadmium or iron. Other putative renal functions of SLC22A17, such as its contribution to osmotic stress adaptation, protection against urinary tract infection, or renal carcinogenesis, are discussed.

The specialist field of "pneumology" is still underrepresented in university clinics in Germany, but this is not the case at the newly founded medical faculty Ostwestfalen-Lippe (OWL) in Bielefeld. This is linked to representing pneumology and internal intensive care medicine in patient care, teaching and research across the board and the opportunity to actively help shape the development of the human medicine faculty in an exciting environment.The early anchoring of the subject "Pneumology" in the model degree program of medical school in OWL (begin winter semester 2021/22) contributes to further visibility and a university medical orientation. In this overview various issues of Pneumology in the Model Degree Program are explored by basic scientists, clinical teachers, members of the medical faculty and a student.In today's Evangelisches Klinikum Bethel (EvKB), pulmonary medicine has a long tradition. The hospital's first lung and infection center was opened in 1927. The EvKB's department for internal medicine, pneumology and intensive care medicine, which has been independent since 2009, is becoming a university clinic for pneumology within the medical faculty OWL. Relevant translational and interdisciplinary research can be intensified.There are 30 "Pneumology" teaching units in the model degree program, which are divided into two study sections using different formats, such as lectures, seminars, hands on courses and skills lab. It is represented in particular in the module complex "Circulation and Respiration". The content of the first phase of teaching was carried out by a module commission, with members representing the subjects involved in the module.Knowledge of the basics from, for example, physiology, pathophysiology, anatomy and pathology are taught to the students in the run-up to the pneumology course. Using the example of physiology, the presentation of the learning content of a basic subject is elaborated in this article.Half of all teaching units on pneumology of the entire course took place in the 2nd semester (in March and April 2022), so that students experienced the clinical relevance of the content at an early stage. There was a particular focus on obstructive airway and restrictive lung diseases. After imparting the basic knowledge of the physical examination of the lungs in the Skills Lab, the most important pathological findings in the above-mentioned diseases on inspection, palpation, auscultation and percussion are demonstrated and practised in patients as part of bedside teaching under supervision.Communication training is also longitudinally integrated into the modular teaching, with a total of more than 200 teaching hours and is performed interdisciplinary. In the "Circulation and Breathing" module eight hours are devoted to this with simulated patients, the anamnesis and therapy advice on classic cardiopulmonary diseases. For the students, integrating the teaching of basic theory and its clinical application for each organ systems represents a challenge in the model degree program, the advantages outweigh from today's perspective., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

The kidney is the main organ that senses changes in systemic oxygen tension, but it is also the key detoxification, transit and excretion site of transition metals (TMs). Pivotal to oxygen sensing are prolyl-hydroxylases (PHDs), which hydroxylate specific residues in hypoxia-inducible factors (HIFs), key transcription factors that orchestrate responses to hypoxia, such as induction of erythropoietin (EPO). The essential TM ion Fe is a key component and regulator of the hypoxia-PHD-HIF-EPO (HPHE) signaling axis, which governs erythropoiesis, angiogenesis, anaerobic metabolism, adaptation, survival and proliferation, and hence cell and body homeostasis. However, inadequate concentrations of essential TMs or entry of non-essential TMs in organisms cause toxicity and disrupt health. Non-essential TMs are toxic because they enter cells and displace essential TMs by ionic and molecular mimicry, e. g. in metalloproteins. Here, we review the molecular mechanisms of HPHE interactions with TMs (Fe, Co, Ni, Cd, Cr, and Pt) as well as their implications in renal physiology, pathophysiology and toxicology. Some TMs, such as Fe and Co, may activate renal HPHE signaling, which may be beneficial under some circumstances, for example, by mitigating renal injuries from other causes, but may also promote pathologies, such as renal cancer development and metastasis. Yet some other TMs appear to disrupt renal HPHE signaling, contributing to the complex picture of TM (nephro-)toxicity. Strikingly, despite a wealth of literature on the topic, current knowledge lacks a deeper molecular understanding of TM interaction with HPHE signaling, in particular in the kidney. This precludes rationale preventive and therapeutic approaches to TM nephrotoxicity, although recently activators of HPHE signaling have become available for therapy., (© 2022. The Author(s).)

Oncogenic multidrug resistance is commonly intrinsic to renal cancer based on the physiological expression of detoxification transporters, particularly ABCB1, thus hampering chemotherapy. ABCB1 activity is directly dependent on its lipid microenvironment, localizing to cholesterol- and sphingomyelin (SM)-rich domains. As ceramides are the sole source for SMs, we hypothesized that ceramide synthase (CerS)-derived ceramides regulate ABCB1 activity. Using data from RNA-Seq databases, we found that patient kidney tumors exhibited increased CerS2 mRNA, which was inversely correlated with CerS6 mRNA in ABCB1 + clear cell carcinomas. Endogenous elevated CerS2 and lower CerS5/6 mRNA and protein resulted in disproportionately higher CerS2 to CerS5/6 activities (approximately twofold) in chemoresistant ABCB1 high (A498, Caki-1) compared with chemosensitive ABCB1 low (ACHN, normal human proximal convoluted tubule cell) cells. In addition, lipidomics analyses by HPLC-MS/MS showed bias toward CerS2-associated C20:0/C20:1-ceramides compared with CerS5/6-associated C14:0/C16:0-ceramides (2:1). SMs were similarly altered. We demonstrated that chemoresistance to doxorubicin in ABCB1 high cells was partially reversed by inhibitors of de novo ceramide synthesis (l-cycloserine) and CerS (fumonisin B 1 ) in cell viability assays. Downregulation of CerS2/6, but not CerS5, attenuated ABCB1 mRNA, protein, plasma membrane localization, rhodamine 123 + efflux transport activity, and doxorubicin resistance. Similar findings were observed with catalytically inactive CerS6-H212A. Furthermore, CerS6-targeting siRNA shifted ceramide and SM composition to ultra long-chain species (C22-C26). Inhibitors of endoplasmic reticulum-associated degradation (eeyarestatin I) and the proteasome (MG132, bortezomib) prevented ABCB1 loss induced by CerS2/6 downregulation. We conclude that a critical balance in ceramide/SM species is prerequisite to ABCB1 expression and functionalization, which could be targeted to reverse multidrug resistance in renal cancers., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe 2+ overload. The nephrotoxic non-essential metal ion Cd 2+ can displace Fe 2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe 2+ and Cd 2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD 3 ] collecting duct cell lines. Cells were exposed to equipotent Cd 2+ (0.5-5 μmol/l) and/or Fe 2+ (50-100 μmol/l) for 4-24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe 2+ -induced mIMCD 3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd 2+ -induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe 2+ prevented Cd 2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe 2+ with desferrioxamine augmented Cd 2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe 2+ , but not Cd 2+ . Because Fe 2+ and Cd 2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate., (© 2021. The Author(s).)

Ever increasing environmental presence of cadmium as a consequence of industrial activities is considered a health hazard and is closely linked to deteriorating global health status. General animal and human cadmium exposure ranges from ingestion of foodstuffs sourced from heavily polluted hotspots and cigarette smoke to widespread contamination of air and water, including cadmium-containing microplastics found in household water. Cadmium is promiscuous in its effects and exerts numerous cellular perturbations based on direct interactions with macromolecules and its capacity to mimic or displace essential physiological ions, such as iron and zinc. Cell organelles use lipid membranes to form complex tightly-regulated, compartmentalized networks with specialized functions, which are fundamental to life. Interorganellar communication is crucial for orchestrating correct cell behavior, such as adaptive stress responses, and can be mediated by the release of signaling molecules, exchange of organelle contents, mechanical force generated through organelle shape changes or direct membrane contact sites. In this review, cadmium effects on organellar structure and function will be critically discussed with particular consideration to disruption of organelle physiology in vertebrates.

Cadmium (Cd 2+ ) is a toxic and non-essential divalent metal ion in eukaryotic cells. Cells can only be targeted by Cd 2+ if it hijacks physiological high-affinity entry pathways, which transport essential divalent metal ions in a process termed "ionic and molecular mimicry". Hence, "free" Cd 2+ ions and Cd 2+ complexed with small organic molecules are transported across cellular membranes via ion channels, carriers and ATP hydrolyzing pumps, whereas receptor-mediated endocytosis (RME) internalizes Cd 2+ -protein complexes. Only Cd 2+ transport pathways validated by stringent methodology, namely electrophysiology, 109 Cd 2+ tracer studies, inductively coupled plasma mass spectrometry, atomic absorption spectroscopy, Cd 2+ -sensitive fluorescent dyes, or specific ligand binding and internalization assays for RME are reviewed whereas indirect correlative studies are excluded. At toxicologically relevant concentrations in the submicromolar range, Cd 2+ permeates voltage-dependent Ca 2+ channels ("T-type" Ca V 3.1, CatSper), transient receptor potential (TRP) channels (TRPA1, TRPV5/6, TRPML1), solute carriers (SLCs) (DMT1/SLC11A2, ZIP8/SLC39A8, ZIP14/SLC39A14), amino acid/cystine transporters (SLC7A9/SLC3A1, SLC7A9/SLC7A13), and Cd 2+ -protein complexes are endocytosed by the lipocalin-2/NGAL receptor SLC22A17. Cd 2+ transport via the mitochondrial Ca 2+ uniporter, ATPases ABCC1/2/5 and transferrin receptor 1 is likely but requires further evidence. Cd 2+ flux occurs through the influx carrier OCT2/SLC22A2, efflux MATE proteins SLC47A1/A2, the efflux ATPase ABCB1, and RME of Cd 2+ -metallothionein by the receptor megalin (low density lipoprotein receptor-related protein 2, LRP2):cubilin albeit at high concentrations thus questioning their relevance in Cd 2+ loading. Which Cd 2+ -protein complexes are internalized by megalin:cubilin in vivo still needs to be determined. A stringent conservative and reductionist approach is mandatory to verify relevance of transport pathways for Cd 2+ toxicity and to overcome dissemination of unsubstantiated conjectures.

Cadmium (Cd(2+)) induces oxidative stress that ultimately defines cell fate and pathology. Mitochondria are the main energy-producing organelles in mammalian cells, but they also have a central role in formation of reactive oxygen species, cell injury, and death signaling. As the kidney is the major target in Cd(2+) toxicity, the roles of oxidative signature and mitochondrial function and biogenesis in Cd(2+)-related stress outcomes were investigated in vitro in cultured rat kidney proximal tubule cells (PTCs) (WKPT-0293 Cl.2) for acute Cd(2+) toxicity (1-30 µM, 24 h) and in vivo in Fischer 344 rats for sub-chronic Cd(2+) toxicity (1 mg/kg CdCl2 subcutaneously, 13 days). Whereas 30 µM Cd(2+) caused ~50 % decrease in cell viability, apoptosis peaked at 10 µM Cd(2+) in PTCs. A steep, dose-dependent decline in reduced glutathione (GSH) content occurred after acute exposure and an increase of the oxidized glutathione (GSSG)/GSH ratio. Quantitative PCR analyses evidenced increased antioxidative enzymes (Sod1, Gclc, Gclm), proapoptotic Bax, metallothioneins 1A/2A, and decreased antiapoptotic proteins (Bcl-xL, Bcl-w). The positive regulator of mitochondrial biogenesis Pparγ and mitochondrial DNA was increased, and cellular ATP was unaffected with Cd(2+) (1-10 µM). In vivo, active caspase-3, and hence apoptosis, was detected by FLIVO injection in the kidney cortex of Cd(2+)-treated rats together with an increase in Bax mRNA. However, antiapoptotic genes (Bcl-2, Bcl-xL, Bcl-w) were also upregulated. Both GSSG and GSH increased with chronic Cd(2+) exposure with no change in GSSG/GSH ratio and augmented expression of antioxidative enzymes (Gpx4, Prdx2). Mitochondrial DNA, mitofusin 2, and Pparα were increased indicating enhanced mitochondrial biogenesis and fusion. Hence, these results demonstrate a clear involvement of higher mitochondria copy numbers or mass and mitochondrial function in acute defense against oxidative stress induced by Cd(2+) in renal PTCs as well as in adaptive processes associated with chronic renal Cd(2+) toxicity.

The environmental toxicant cadmium (Cd) enters the food chain. A substantial proportion of Cd in nutrients of plant origin is present as Cd-metallothionein (CdMT) and Cd-phytochelatin (CdPC) complexes, which may be absorbed and transcytosed intact by colonic enterocytes following bacterial fermentation and contribute to systemic Cd toxicity, e.g. in liver and kidneys. We have recently demonstrated that the receptor for human neutrophil gelatinase-associated lipocalin (hNGAL) is expressed in human colon and colon-like Caco-2 BBE cells where it mediates transcytosis of MT and PC. Here we show in colon-like Caco-2 BBE cells that hNGAL receptor (hNGAL-R) dependent toxicity is significantly higher with CdMT than with CdPC3 (2.5-50μM Cd(2+) complexed to MT or PC3 for ≤24h), using MTT assay. Fluorescence-labelled A546-MT, but not A488-PC3 (both 700nM), co-localizes with the lysosomal marker cathepsin-B, as determined by confocal microscopy. In transwell experiments with confluent monolayers, transcytosis efficiency (i.e. the ratio of basal delivery to apical decrease) of A546-MT is decreased compared to A488-PC3 (both 700nM). The tubulin polymerization disruptor nocodazole (16.7μM) almost abolished CdMT and CdPC3 toxicity, reduced apical uptake of both A546-MT and A488-PC3, but increased transcytosis efficiency of A546-MT compared to that of A488-PC3 by preventing trafficking of A546-MT to lysosomes. Hence, following hNGAL-R dependent endocytosis of CdMT/CdPC3 in colonic epithelia, a nocodazole-sensitive trafficking pathway may preferentially target CdMT, but not CdPC3, to lysosomes, causing increased colonic epithelial toxicity but reduced systemic toxicity., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Nickel and nickel compounds are carcinogens that target the lungs and kidneys causing cell death or cell survival adaptation. The multidrug resistance P-glycoprotein ABCB1 protects cells against toxic metabolites and xenobiotics and is upregulated in many cancer cell types. Here, we investigated the role of ABCB1 in nickel-induced stress signaling mediated by reactive oxygen species (ROS) and ceramides. In renal proximal tubule cells, nickel chloride (0.1-0.25 mM) increased both ROS formation, detected by 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate, and cellular ceramides, which were determined by lipid dot blot and surface immunostaining, culminating in decreased cell viability, increased DNA fragmentation, augmented PARP-1 cleavage, and increased ABCB1 mRNA and protein. Inhibitors of the de novo ceramide synthesis pathway (fumonisin B1, L-cycloserine) and an antioxidant (α-tocopherol) attenuated nickel-induced toxicity as well as induction of ABCB1. ABCB1 protects against nickel toxicity as PSC833, an ABCB1 blocker, augmented the decrease in cell viability by nickel. Moreover, nickel toxicity was attenuated in renal MDCK cells stably overexpressing ABCB1. In agreement with previous data that demonstrated extrusion of (glucosyl)ceramides by ABCB1 (Lee et al. in Toxicol Sci 121:343, 2011), PSC833 increased total cellular ceramides by >2-fold after nickel treatment. Further, glucosylceramide synthase (GCS) mRNA is upregulated by nickel at 3 h by ~1.5-fold but declined with prolonged exposures (6-24 h). Inhibition of GCS with C9DGJ or knockdown of GCS with siRNA significantly attenuated nickel toxicity. In conclusion, nickel induces a ROS-ceramide pathway to cause apoptotic cell death as well as activate adaptive survival responses, including upregulation of ABCB1, which improves cell survival by extruding proapoptotic (glucosyl)ceramides.

The detrimental health effects of cadmium (Cd) were first described in the mid 19th century. As part of industrial developments, increasing usage of Cd has led to widespread contamination of the environment that threatens human health, particularly today. Rather than acute, lethal exposures, the real challenge in the 21st century in a global setting seems to be chronic low Cd exposure (CLCE), mainly from dietary sources. Ubiquity of Cd makes it a serious environmental health problem that needs to be thoroughly assessed because it already affects or will affect large proportions of the world's population. CLCE is a health problem that affects increasingly organ toxicity, especially nephrotoxicity, without a known threshold, implying that there is currently no safe limit for CLCE. In this chapter, we summarize current knowledge on the sources of Cd in the environment, describe the entry pathways for Cd into mammalian organisms, sum up the major organs targeted by acute or chronic Cd exposure and review the impact of Cd on organ function and human health. We also aim to put early pioneering studies on Cd poisoning into perspective in the context of recent ground-breaking prospective long-term population studies, which link CLCE to leading causes of diseases in modern societies - cancer, diabetes, and cardiovascular diseases, and of state-of-the-art studies detailing cellular and molecular mechanisms of acute and chronic Cd toxicity.

Cadmium (Cd) is nephrotoxic. Circulating Cd-metallothionein complexes (CdMT) are filtered by the kidney, reabsorbed by proximal tubule cells (PTC) via receptor-mediated endocytosis, and trafficked to lysosomes which results in apoptosis. ADP-ribosylation factors (Arfs) regulate vesicular trafficking. Arf1 is traditionally associated with the secretory pathway, but has been recently found involved in endocytotic trafficking in PTC. Hence, the role of Arf1 was investigated in MT-1 and transferrin (Tf) endocytosis, and in CdMT-1-induced cell death in a PTC line by overexpressing Arf1-wildtype (WT) or dominant-negative mutant Arf1-T31N. Endogenous Arf1 distribution in PTC was punctate throughout the cytosol, but was not detected in the plasma membrane. Arf1 colocalized with markers for sorting to late endosomes (Rab7, CLC6). Arf1 weakly overlapped with the late endosomal/lysosomal marker CLC7, but not with markers for early (Rab5, CLC5) and recycling endosomes (Rab11). Arf1-T31N significantly attenuated CdMT-1 toxicity by ∼60% when compared to Arf1-WT. However, overexpression of Arf1-T31N did not prevent internalization of Alexa Fluor 546-coupled Tf or MT-1 which accumulated in an EEA1-positive early endocytotic compartment, but not in Arf1-WT overexpressing cells. We conclude that Arf1 is involved in trafficking of protein-metal complexes, including CdMT, to late endosomes/lysosomes in renal PTC., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

An orientational grating with reduced scattering noise is formed in fullerene-doped and undoped homeotropic nematic liquid crystal cells by simultaneous application of both spatially modulated light and ac electric field. The first-order diffraction efficiency obtained in the fullerene-doped cell reaches ~30 %, approaching the maximum value predicted by theory. Effective nonlinear index coefficient is ~0.9 cm2/W and ~1000 times larger than previous observations in C(60)-doped nematic liquid crystals using a dc field. Grating formation time can be as short as 1 s, which is ~100 times shorter than those found by us using a dc field and previous studies.

The nephrotoxic metal Cd(2+) causes mitochondrial damage and apoptosis of kidney proximal tubule cells. A K(+) cycle involving a K(+) uniporter and a K(+)/H(+) exchanger in the inner mitochondrial membrane (IMM) is thought to contribute to the maintenance of the structural and functional integrity of mitochondria. In the present study, we have investigated the effect of Cd(2+) on K(+) cycling in rat kidney cortex mitochondria. Cd(2+) (EC(50) approximately 19 microM) induced swelling of nonenergized mitochondria suspended in isotonic salt solutions according to the sequence KCl = NaCl > LiCl >> choline chloride. Cd(2+)-induced swelling of energized mitochondria had a similar EC(50) value and showed the same cation dependence but was followed by a spontaneous contraction. Mitochondrial Ca(2+) uniporter (MCU) blockers, but not permeability transition pore inhibitors, abolished swelling, suggesting the need for Cd(2+) influx through the MCU for swelling to occur. Complete loss of mitochondrial membrane potential (DeltaPsi(m)) induced by K(+) influx did not prevent contraction, but addition of the K(+)/H(+) exchanger blocker, quinine (1 mM), or the electroneutral protonophore nigericin (0.4 microM), abolished contraction, suggesting the mitochondrial pH gradient (DeltapH(m)) driving contraction. Accordingly, a quinine-sensitive partial dissipation of DeltapH(m) was coincident with the swelling-contraction phase. The data indicate that Cd(2+) enters the matrix through the MCU to activate a K(+) cycle. Initial K(+) load via a Cd(2+)-activated K(+) uniporter in the IMM causes osmotic swelling and breakdown of DeltaPsi(m) and triggers quinine-sensitive K(+)/H(+) exchange and contraction. Thus Cd(2+)-induced activation of a K(+) cycle contributes to the dissipation of the mitochondrial protonmotive force.