Complexes formed by the siderophore-based monosulfactam antibiotic BAL30072 and their interaction with the outer membrane receptor PiuA of P. aeruginosa.

Nuclear magnetic resonance and infrared spectroscopy have been used to investigate the formation of complexes of BAL30072 with Fe3+ and Ga3+ in solution and to collect geometrical parameters supporting reliable 3D structure models. Structural models for the ligand-metal complexes with different stoichiometries have been characterized using density functional theory calculations. Blind ensemble docking to the PiuA receptor from P. aeruginosa was performed for the different complexes to compare binding affinities and statistics of the residues most frequently contacted. When compared to analogues, BAL30072 was found to have an intrinsic propensity to form complexes with low ligand-to-metal stoichiometry. By using one of the sulfate oxygen atoms as a third donor in addition to the bidentate pyridinone moiety, BAL30072 can form a L2M complex, which was predicted to be the one with the best binding affinity to PiuA. The example of BAL30072 strongly suggests that a lower stoichiometry might be the one recognized by the receptor, so that to focus only on the highest stoichiometry might be misleading for siderophores with less than six donors.

Preacinetobactin not acinetobactin is essential for iron uptake by the BauA transporter of the pathogen Acinetobacter baumannii.

New strategies are urgently required to develop antibiotics. The siderophore uptake system has attracted considerable attention, but rational design of siderophore antibiotic conjugates requires knowledge of recognition by the cognate outer-membrane transporter. Acinetobacter baumannii is a serious pathogen, which utilizes (pre)acinetobactin to scavenge iron from the host. We report the structure of the (pre)acinetobactin transporter BauA bound to the siderophore, identifying the structural determinants of recognition. Detailed biophysical analysis confirms that BauA recognises preacinetobactin. We show that acinetobactin is not recognised by the protein, thus preacinetobactin is essential for iron uptake. The structure shows and NMR confirms that under physiological conditions, a molecule of acinetobactin will bind to two free coordination sites on the iron preacinetobactin complex. The ability to recognise a heterotrimeric iron-preacinetobactin-acinetobactin complex may rationalize contradictory reports in the literature. These results open new avenues for the design of novel antibiotic conjugates (trojan horse) antibiotics.

Folded Structure and Membrane Affinity of the N-Terminal Domain of the Three Human Isoforms of the Mitochondrial Voltage-Dependent Anion-Selective Channel.

Voltage-dependent anion-selective channels (VDACs) are primarily located in the mitochondrial outer membrane (MOM). They are essential for the regulation of ion and metabolite exchanges. In particular, their role in energy-related nucleotide exchange has many implications in apoptosis, cancer, and neurodegenerative diseases. It has been proposed that VDACs' functions are regulated by mobility of the N-terminal helical domain, which is bound to the inner wall of the main ß-barrel domain but exists in equilibrium between the bound-folded and the unbound-unfolded state. When the N-terminal domain detaches from the channel's wall and eventually leaves the lumen, it can either stay exposed to the cytosolic environment or interact with the outer leaflet of the MOM; then, it may also interact with other protein partners. In humans, three different VDAC isoforms are expressed at different tissue-specific levels with evidence of distinct roles. Although the N-terminal domains share high sequence similarity, important differences do exist, with the functionality of the entire protein mostly attributed to them. In this work, the three-dimensional structure and membrane affinity of the three isolated hVDAC N-terminal peptides have been compared through Fourier-transform infrared and NMR spectroscopy in combination with molecular dynamics simulations, and measurement of the surface pressure of lipid monolayers. Although peptides were studied as isolated from the ß-barrel domain, the observed differences are relevant for those whole protein's functions in which a protein-protein interaction is mediated by the N-terminal domain.

Acute Kidney Injury and Chronic Kidney Disease in the Elderly and Polypharmacy.

BACKGROUND: Acute kidney injury (AKI) incidence is reported to be 10 times higher in aged people. Related to their higher prevalence of chronic kidney disease (CKD), older patients are at high risk of toxic effects driven by drugs. METHODS: The demographics, hospitalizations, visits to the Emergency Department, pharmacological therapy, and lab tests were analyzed in 71,588 individuals. RESULTS: Data showed a higher prevalence of AKI as well as CKD in the elderly as compared to the younger group, with an associated very high mortality. A broad number of drugs was prescribed, ranging from 1 to 35, the majority being between 5 and 9 drugs. CONCLUSION: Elderly patients who developed AKI had a higher number of hospitalizations (underlying frailty), were more likely to progress to more severe stages of CKD and to be affected by other non-renal pathologies (associated comorbidities) and to be given heavier pharmacological prescriptions (polypharmacy).

Effects of amphipathic profile regularization on structural order and interaction with membrane models of two highly cationic branched peptides with ß-sheet propensity.

Antimicrobial peptides attracted increasing interest in last decades due to the rising concern of multi-drug resistant pathogens. Dendrimeric peptides are branched molecules with multiple copies of one peptide functional unit bound to the central core. Compared to linear analogues, they usually show improved activity and lower susceptibility to proteases. Knowledge of structure-function relationship is fundamental to tailor their properties. This work is focused on SB056, the smallest example of dendrimeric peptide, whose amino acid sequence is WKKIRVRLSA. Two copies are bound to the α- and ε- nitrogen of one lysine core. An 8-aminooctanamide was added at the C-terminus to improve membrane affinity. Its propensity for ß-type structures is also interesting, since helical peptides were already thoroughly studied. Moreover, SB056 maintains activity at physiological osmolarity, a typical limitation of natural peptides. An optimized analogue with improved performance was designed, ß-SB056, which differs only in the relative position of the first two residues (KWKIRVRLSA). This produced remarkable differences. Structure order and aggregation behavior were characterized by using complementary techniques and membrane models with different negative charge. Infrared spectroscopy showed different propensity for ordered ß-sheets. Lipid monolayers' surface pressure was measured to estimate the area/peptide and the ability to perturb lipid packing. Fluorescence spectroscopy was applied to compare peptide insertion into the lipid bilayer. Such small change in primary structure produced fundamental differences in their aggregation behavior. A regular amphipathic peptide's primary structure was responsible for ordered ß-sheets in a charge independent fashion, in contrast to unordered aggregates formed by the former analogue.

[Bardet-Biedl syndrome and Kidney failure: a case report].

Bardet-Biedl Syndrome (BBS) is a rare multi-systemic disease with autosomal recessive transmission. BBS was at first considered to be homogeneous as for its genetics, but subsequent studies have shown an extensive gene variability. Currently, 21 genes (BBS1-21) present on different chromosomes have been mapped: these genes are responsible for BBS phenotypes and they show a great heterogeneity of mutations.The most common genes are BBS1 (locus 11q13) and BBS10.We show here the case of a 50 year old patient with BBS. Medical History: retinitis pigmentosa at 4 years of age evolved to complete blindness, generalized epilepsy crises, poly-syndactyly, left-hand malformation. In April 1986 developed an epileptic episode: on that occasion Chronic Kidney Failure (CKF) diagnosis and starting of haemodialysis. In 1989, hospitalization for epileptic seizures. In 2009 the patient underwent kidney transplantation from deceased donor. Immunosuppressive initial protocol: Basiliximab, Azathioprine, Tacrolimus, Steroid, and Tacrolimus, Azathioprine, Steroid at hospital discharge. Post-operative care complicated by respiratory failure with mechanical ventilation assistance. During hospitalization, the neurological picture remained stable. At hospital discharge Creatinine 1.8 mg/dl. Subsequently, immunosuppressant were gradually tapered until monotherapy with Tacrolimus. At present the patient's conditions appear to be good, renal function has remained substantially stable with Creatinine between 1.4-1.5 mg/dl and glomerular filtration rate (GFR) estimated at 39-42 mL/min/1.73 m ² according to MDRD study Equation. This case shows the possibility to successfully manage a BBS-affected uremic patient, despite the complexity of the pathology and the aggravating factor of extreme rarity in diagnostic pathway.

[Clinical competence in Nephrology: proposal of an evaluation pathway and definition of professional levels]. / Le competenze in Nefrologia: proposta di un percorso di valutazione e di definizione di livelli professionali.

The need to assess clinical competencies in a medical environment is an intriguing issue due to progressive involvement of young physicians in clinical practice, as well as for connections tied to evaluation systems to define postgraduate training and career progression. To reach this goal, system must be based upon contributions that are aimed to achieve a clear and homogeneous evaluation pathway and strictly related to the continuing medical education institution (credits). All these presuppositions are instrumental for the proposal of a sheet which could allow a data retrieval useful to depict a career progression by means of: identification of reproducible parameters along with clear standards; advices for indicators; objective judgments that could drive to a score meaningful for reaching higher steps in the performance evaluation. This work had been carried out at Local Health Authority 1 of Cuneo (ASLCN1) from 2014 to 2017 in order to provide a widely usable evaluation framework for all the medical workers. Aim of this work is thus to show up an original methodology, as much as possible based upon objective items, related to the professional improvement of a nephrologist working in Hospital and following him along his clinical course.

The Semi-Synthetic Peptide Lin-SB056-1 in Combination with EDTA Exerts Strong Antimicrobial and Antibiofilm Activity against Pseudomonas aeruginosa in Conditions Mimicking Cystic Fibrosis Sputum.

Pseudomonas aeruginosa is a major cause of chronic lung infections in cystic fibrosis (CF) patients. The ability of the bacterium to form biofilms and the presence of a thick and stagnant mucus in the airways of CF patients largely contribute to antibiotic therapy failure and demand for new antimicrobial agents able to act in the CF environment. The present study investigated the anti-P. aeruginosa activity of lin-SB056-1, a recently described semi-synthetic antimicrobial peptide, used alone and in combination with the cation chelator ethylenediaminetetraacetic acid (EDTA). Bactericidal assays were carried out in standard culture conditions and in an artificial sputum medium (ASM) closely resembling the CF environment. Peptide's structure and interaction with large unilamellar vesicles in media with different ionic strengths were also investigated through infrared spectroscopy. Lin-SB056-1 demonstrated fast and strong bactericidal activity against both mucoid and non-mucoid strains of P. aeruginosa in planktonic form and, in combination with EDTA, caused significant reduction of the biomass of P. aeruginosa mature biofilms. In ASM, the peptide/EDTA combination exerted a strong bactericidal effect and inhibited the formation of biofilm-like structures of P. aeruginosa. Overall, the results obtained highlight the potential of the lin-SB056-1/EDTA combination for the treatment of P. aeruginosa lung infections in CF patients.

The discovery of IDX21437: Design, synthesis and antiviral evaluation of 2'-α-chloro-2'-ß-C-methyl branched uridine pronucleotides as potent liver-targeted HCV polymerase inhibitors.

Herein we describe the discovery of IDX21437 35b, a novel RPd-aminoacid-based phosphoramidate prodrug of 2'-α-chloro-2'-ß-C-methyluridine monophosphate. Its corresponding triphosphate 6 is a potent inhibitor of the HCV NS5B RNA-dependent RNA polymerase (RdRp). Despite showing very weak activity in the in vitro Huh-7 cell based HCV replicon assay, 35b demonstrated high levels of active triphosphate 6 in mouse liver and human hepatocytes. A biochemical study revealed that the metabolism of 35b was mainly attributed to carboxyesterase 1 (CES1), an enzyme which is underexpressed in HCV Huh-7-derived replicon cells. Furthermore, due to its metabolic activation, 35b was efficiently processed in liver cells compared to other cell types, including human cardiomyocytes. The selected RP diastereoisomeric configuration of 35b was assigned by X-ray structural determination. 35b is currently in Phase II clinical trials for the treatment of HCV infection.

[Hyperuricemia and gene mutations: a case report].

Hyperuricemia is frequently found in nephrology. The case presented may be useful to clarify some pathogenetic aspects. It is a patient of 18 years, hyperuricaemic. Non-consanguineous parents, hyperuricemia in the paternal line, not neuropsychiatric disorders in the family. Delay in neuromotor acquisitions, average intellectual disabilities, anxiety disorder, obsessive-compulsive personality traits. Normal renal function and renal ultrasound. Evidence of hyperuricemia in 2015. Never gouty episodes and / or lithiasis, initiated allopurinol 100 mg on alternate days, with no side effects, urea in the control range, slightly below normal uricuria. Given the complex clinical, he carried out a genetic analysis of array-CGH. He showed a deletion on the short arm of chromosome 3 (3p12.3) and a duplication of the long arm of chromosome 1 (19q13-42). The deletion 3p12.3 (paternal inheritance), involves the ROBO2 gene. Duplication 19q13.42, (maternal inheritance), includes NLRP12, DPRX, ZNF331 genes. The ROBO2 gene with its mutation, is associated with vesicoureteral reflux. The NLRP12 gene encodes proteins called "Nalps", forming a subfamily of proteins "CATERPILLAR". Many "Nalps" as well as the "Nalps 12" have an N-terminal domain (DYP) with a purin. Since uric acid is a byproduct of purine metabolism, considered the familiarity, we believe that we can hypothesize that the mutations found. In particular those concerning the NLRP-12 gene, may have a role in the presence of hyperuricemia. We believe that in patients with hyperuricemia, associated with a particular impairment of neurological picture, it is likely that there is a subtended common genetic deficiency.

Antimicrobial Dendrimeric Peptides: Structure, Activity and New Therapeutic Applications.

Microbial resistance to conventional antibiotics is one of the most outstanding medical and scientific challenges of our times. Despite the recognised need for new anti-infective agents, however, very few new drugs have been brought to the market and to the clinic in the last three decades. This review highlights the properties of a new class of antibiotics, namely dendrimeric peptides. These intriguing novel compounds, generally made of multiple peptidic sequences linked to an inner branched core, display an array of antibacterial, antiviral and antifungal activities, usually coupled to low haemolytic activity. In addition, several peptides synthesized in oligobranched form proved to be promising tools for the selective treatment of cancer cells.

The singular behavior of a ß-type semi-synthetic two branched polypeptide: three-dimensional structure and mode of action.

Dendrimeric peptides make a versatile group of bioactive peptidomimetics and a potential new class of antimicrobial agents to tackle the pressing threat of multi-drug resistant pathogens. These are branched supramolecular assemblies where multiple copies of the bioactive unit are linked to a central core. Beyond their antimicrobial activity, dendrimeric peptides could also be designed to functionalize the surface of nanoparticles or materials for other medical uses. Despite these properties, however, little is known about the structure-function relationship of such compounds, which is key to unveil the fundamental physico-chemical parameters and design analogues with desired attributes. To close this gap, we focused on a semi-synthetic, two-branched peptide, SB056, endowed with remarkable activity against both Gram-positive and Gram-negative bacteria and limited cytotoxicity. SB056 can be considered the smallest prototypical dendrimeric peptide, with the core restricted to a single lysine residue and only two copies of the same highly cationic 10-mer polypeptide; an octanamide tail is present at the C-terminus. Combining NMR and Molecular Dynamics simulations, we have determined the 3D structure of two analogues. Fluorescence spectroscopy was applied to investigate the water-bilayer partition in the presence of vesicles of variable charge. Vesicle leakage assays were also performed and the experimental data were analyzed by applying an iterative Monte Carlo scheme to estimate the minimum number of bound peptides needed to achieve the release. We unveiled a singular beta hairpin-type structure determined by the peptide chains only, with the octanamide tail available for further functionalization to add new potential properties without affecting the structure.

Rational modification of a dendrimeric peptide with antimicrobial activity: consequences on membrane-binding and biological properties.

Peptide-based antibiotics might help containing the rising tide of antimicrobial resistance. We developed SB056, a semi-synthetic peptide with a dimeric dendrimer scaffold, active against both Gram-negative and Gram-positive bacteria. Being the mechanism of SB056 attributed to disruption of bacterial membranes, we enhanced the amphiphilic profile of the original, empirically derived sequence [WKKIRVRLSA-NH2] by interchanging the first two residues [KWKIRVRLSA-NH2], and explored the effects of this modification on the interaction of peptide, both in linear and dimeric forms, with model membranes and on antimicrobial activity. Results obtained against Escherichia coli and Staphylococcus aureus planktonic strains, with or without salts at physiological concentrations, confirmed the added value of dendrimeric structure over the linear one, especially at physiological ionic strength, and the impact of the higher amphipathicity obtained through sequence modification on enhancing peptide performances. SB056 peptides also displayed intriguing antibiofilm properties. Staphylococcus epidermidis was the most susceptible strain in sessile form, notably to optimized linear analog lin-SB056-1 and the wild-type dendrimer den-SB056. Membrane affinity of all peptides increased with the percentage of negatively charged lipids and was less influenced by the presence of salt in the case of dendrimeric peptides. The analog lin-SB056-1 displayed the highest overall affinity, even for zwitterionic PC bilayers. Thus, in addition to electrostatics, distribution of charged/polar and hydrophobic residues along the sequence might have a significant role in driving peptide-lipid interaction. Supporting this view, dendrimeric analog den-SB056-1 retained greater membrane affinity in the presence of salt than den-SB056, despite the fact that they bear exactly the same net positive charge.

[Hypokalemia in Lennox-Gastaut syndrome]. / Ipopotassiemia in sindrome di Lennox-Gastaut.

The Lennox-Gastaut Syndrome (LGS) is a childhood epileptic encephalopathy. Incidence: 1/1.000.000/year, prevalence: 15/100.000. LGS covers 5-10% of epileptic patients and 1-2% of childhood epilepsies. Also referred to as cryptogenic or symptomatic generalized epilepsy. LGS is characterized by: multiple seizures (atypical absences, axial tonic seizures and sudden atonic or myoclonic falls), diffuse slow cryptic EEG waves when awake (<3 Hz), fast rhythmic peaks (10 Hz) during sleep, mental retardation and personality disorders. The LGS is not responding to treatment. Some new drugs have proven to be effective in controlling the disease (Felbamate, Lamotrigine, Topiramate, Levetiracetam). The mortality rate is about 5%; only rarely death is due to epilepsy, which is usually caused by stroke or epileptic episodes. Here we describe the case of a 45-year-old female patient with LGS, severe hypokalemia, mental retardation and focal seizures. Normal renal function: creatinine 0.9 mg/dl, urea 26 mg/dl, creatinine clearance 96 ml/min, serum potassium levels to the minimum: 3.5 mEq/L. This level of potassium, however, had been achieved with the assumption of 8 oral tablets/day of potassium chloride. Osmotic diuresis, use of diuretics, Bartter, Gitelman (normal urinary calcium and magnesium) and pseudo-Bartter syndromes were all excluded whereas aldosteronism was found. Our findings lead to hypokalemia related to assumption of topiramate and hyperaldosteronism. Reduction in drug intake was not effective due to the increased seizures, so the drug was maintained, along with potassium supplementation. In conclusion, the patient has been diagnosed with hypokalemia and iatrogenic hyperaldosteronism, rare in our outpatient practice.

[Rhabdomyolysis from gabapentin: a case report]. / Rabdomiolisi da gabapentin: a case report.

Gabapentin (GBP) is a drug with different indications.Is not metabolized and is excreted by the kidney. The common side effects are: arthralgia, myalgia, fatigue, dizziness and ataxia. Rhabdomyolysis is an extremely rare side effect. This latter, that can be caused by trauma, strenuous exercise, infections, drugs and toxins, is a syndrome characterized by loss of skeletal muscle resulting in the release of myocyte components in the circulation. Following a case of rhabdomyolysis caused by GBP in patient with chronic renal failure (CRF). A 65-year-old diabetic men, in peritoneal dialysis (PD), affected by ischemic and hypokinetic cardiomyopathy, sensorimotor neuropathy. The patient reported: weakness, diffuse myalgias, hypotension. He had been taking GBP for three days, after the failure of therapies with tricyclic antidepressants, opioids and NSAIDs. Laboratory tests confirmed the increase of the indices of muscle necrosis.The immediate withdrawal of the drug in association with CAPD dialysis treatment, led to improvement of the clinical and biochemical parameters. During the last 10 years, 3 cases of rhabdomyolysis referred to the assumption of GBP have been reported. The use of PD for treatment of acute renal failure, has been significantly reduced over the years. The effectiveness of the purification method is much lower than the one with the continuous extracorporeal treatments. In conclusion, GBP may be associated with rhabdomyolysis. Since GBP toxicity in CRF patients is often overlooked, a better awareness of this phenomenon and a thorough follow-up of laboratory tests to detect any possible early adverse reaction is suggested.

Conformational analysis and cytotoxic activities of the frog skin host-defense peptide, hymenochirin-1Pa.

Hymenochirin-1Pa (LKLSPKTKDTLKKVLKGAIKGAIAIASMA-NH2) is a host-defense peptide first isolated from skin secretions of the frog Pseudhymenochirus merlini (Pipidae). A nuclear magnetic resonance structural investigation demonstrates that the peptide has a random coil conformation in water but, in the membrane-mimetic solvent 50% (v/v) trifluoroethanol-water adopts a well-defined conformation characterized by two α-helical domains from residues K6 to G17 and from G21 to M28, with the N-terminal region unfolded. The presence of a GXXXG domain, the most common structural motif found at the interface between interacting trans-membrane helices, between residues 17 and 21, introduces a kink corresponding to a deviation from linearity of 93 ± 31°. Hymenochirin-1Pa shows broad spectrum anti-bacterial activity, including high potency against multidrug-resistant clinical isolates of Staphylococcus aureus, Acinetobacter baumannii, and Stenotrophomonas maltophilia. The peptide also shows high cytotoxic potency against human non-small lung adenocarcinoma A549 cells, breast adenocarcinoma MDA-MB-231 cells, and colorectal adenocarcinoma HT-29 cells but its therapeutic potential as an anti-cancer agent is limited by moderate hemolytic activity against human erythrocytes and lack of selectivity for tumor cells. Increasing cationicity of the peptide by substituting the Asp(9) residue by either L-Lys (K) or D-Lys (k) has relatively minor effects on antimicrobial and anti-tumor potencies but the [D9k] analog is non-hemolytic LC50 > 400 µM. Thus, [D9k]hymenochirin-1Pa may serve as a template for the design of non-toxic antimicrobial agents for use against multidrug-resistant pathogenic bacteria.

[Prune-Belly Syndrome: a case report]. / Sindrome Prune-Belly: un caso clinico.

Prune-Belly Syndrome (PBS) is a rare congenital syndrome characterized by the absence of abdominal muscles, anomalies in the urinary tract, megaureter, cryptorchidism or testicular agenesis, hypertension and worsening chronic kidney disease (CKD). The incidence is estimated between 1 out of 35,000 and 1 out of 50,000 born alive, and it affects males in prevalence (97%). In the present study we describe the case of a 38 year old male patient (followed since May 2011) affected by PBS, CKD, one functional kidney at the scintigraphy, pediatric testicular implants, bladder surgery and correction of pectus excavatum. At the beginning of the observation, renal function was deteriorated, with a creatinine 3.3 mg/dl, GFR calculated at MDRD 23 ml/min, proteinuria in nephrotic range (4 g/day), high blood pressure, anemia and hyperparathyroidism. In the following examinations renal function framework worsened, despite the adoption of a low-protein diet. Due to the functional trend, the patient was prescribed hemodialysis as substitute treatment. In January 2013 a first attempt of artero-venous fistula (AVF) did not succeed, while a new AVF in March 2013 resulted effective. In July hemodialysis was started. In the future, we expect to insert the patient in the Kidney Transplant List (since surgical feasibility has already been positively evaluated). Our case is quite peculiar due to the late beginning of substitute treatment. Further, SPB represents a challenge that, in the absence of a prompt and effective treatment, inevitably it leads to terminal uremia; nevertheless, given a proper treatment, a transplant with good chances of success can be envisaged.

Synthesis of 2'-O,4'-C-alkylene-bridged ribonucleosides and their evaluation as inhibitors of HCV NS5B polymerase.

The synthesis of 2'-O,4'-C-methylene-bridged bicyclic guanine ribonucleosides bearing 2'-C-methyl or 5'-C-methyl modifications is described. Key to the successful installation of the methyl functionality in both cases was the use of a one-pot oxidation-Grignard procedure to avoid formation of the respective unreactive hydrates prior to alkylation. The 2'-C-methyl- and 5'-C-methyl-modified bicyclic guanosines were evaluated, along with the known uracil-, cytosine-, adenine-, guanine-LNA and guanine-ENA nucleosides, as potential antiviral agents and found to be inactive in the hepatitis C virus (HCV) cell-based replicon assay. Examination of the corresponding nucleoside triphosphates, however, against the purified HCV NS5B polymerase indicated that LNA-G and 2'-C-methyl-LNA-G are potent inhibitors of both 1b wild type and S282T mutant enzymes in vitro. Activity was further demonstrated for the LNA-G-triphosphate against HCV NS5B polymerase genotypes 1a, 2a, 3a and 4a. A phosphorylation by-pass prodrug strategy may be required to promote anti-HCV activity in the replicon assay.

[Chronic uremia and palliative care]. / Insufficienza renale cronica "end stage": cure intensive e cure palliative.

Nowadays the choice to start with a renal replacement therapy (or its withdrawal once begun) is a critical issue leading to review the paradigm of constantly treating terminal uremia by means of dialysis technologies, without caring for effective prognosis nor for patients preferences, in a more affordable physician-patient relationship. Furthermore dialysis patients mean age is increasing and such population bears the burden of comorbidities that seriously affect survival and quality of life. In any case, dialysis withdrawing does not mean neglecting the patient: the start, or continuation of a very low protein diet program may represent a reasonable alternative, not only for uremic symptoms control but also providing a slowing of disease progression (at least postponing further the start of renal replacement therapy). Basically, in our opinion, the decision to start dialysis in an eligible patient, mainly in the elderly or frails, it should be driven by an adequate balance among all the factors. These factors play a role not only concerning survival, but also in life quality issues and patients preferences. Thus, we argue that ethical issues must be taken into account as well as compelling clinical factors which usually nephrologists refer to. To pursue this goal, it could be useful to set up specific educational pathways addressed to physicians, nurses and technicians of renal units. It also could be instrumental in developing new strategies to manage end stage renal failure, considering not only hospital facilities,but also nursing and patients homes. Incoming guidelines could help nephrologists in improving their behaviors to face these new issues.

Telbivudine, a nucleoside analog inhibitor of HBV polymerase, has a different in vitro cross-resistance profile than the nucleotide analog inhibitors adefovir and tenofovir.

Telbivudine, a nucleoside analog inhibitor of the viral polymerase of hepatitis B virus (HBV), has been approved for the treatment of chronic HBV infection, along with the nucleoside inhibitors lamivudine and entecavir, and the nucleotide inhibitors adefovir and tenofovir. The resistance profiles of these agents were investigated via drug treatment of HepG2 cells stably transfected with wild-type or mutant HBV genomes bearing known resistance mutations. Telbivudine was not active against HBV strains bearing lamivudine mutations L180M/M204V/I but remained active against the M204V single mutant in vitro, potentially explaining the difference in resistance profiles between telbivudine and lamivudine. Against HBV genomes with known telbivudine-resistance mutations, M204I and L80I/M204I, telbivudine, lamivudine and entecavir lost 353- to >1000-fold activity whereas adefovir and tenofovir exhibited no more than 3-5-fold change. Conversely, against HBV cell lines expressing adefovir resistance mutations N236T and A181V, or the A194T mutant associated with resistance to tenofovir, telbivudine remained active as shown by respective fold-changes of 0.5 (N236T) and 1.0 (A181V and A194T). These in vitro results indicate that nucleoside and nucleotide drugs have different cross-resistance profiles. The addition of telbivudine to ongoing adefovir therapy could provide effective antiviral therapy to patients who develop adefovir resistance.