The interplay between sodium/glucose cotransporter type 2 and mitochondrial ionic environment

Mitochondrial volume is maintained through the permeability of the inner mitochondrial membrane by a specific aquaporin and the osmotic balance between the mitochondrial matrix and cellular cytoplasm. Various electrolytes, such as calcium and hydrogen ions, potassium, and sodium, as well as other osmotic substances, affect the swelling of mitochondria. Intracellular glucose levels may also affect mitochondrial swelling, although the relationship between mitochondrial ion homeostasis and intracellular glucose is poorly understood. This article reviews what is currently known about how the Sodium-Glucose transporter (SGLT) may impact mitochondrial sodium (Na+) homeostasis. SGLTs regulate intracellular glucose and sodium levels and, therefore, interfere with mitochondrial ion homeostasis because mitochondrial Na+ is closely linked to cytoplasmic calcium and sodium dynamics. Recently, a large amount of data has been available on the effects of SGLT2 inhibitors on mitochondria in different cell types, including renal proximal tubule cells, endothelial cells, mesangial cells, podocytes, neuronal cells, and cardiac cells. The current evidence suggests that SGLT inhibitors (SGLTi) may affect mitochondrial dynamics regarding intracellular Sodium and hydrogen ions. Although the regulation of mitochondrial ion channels by SGLTs is still in its infancy, the evidence accumulated thus far of the effect of SGLTi on mitochondrial functions certainly will foster further research in this direction.

[Apheresis Techniques for the Treatment of Hyperbilirubinemia in the Nephrology Unit]

Therapeutic apheresis is an important hematological and nephrological method for conditions with altered plasma composition. It is also indicated for the removal of protein-bound molecules, such as bilirubin. Several techniques can remove these compounds, such as the extracorporeal circulation molecular adsorption system (MARS), plasma exchange (PEX), and plasma adsorption and perfusion (PAP). Here we report our experience in the comparison between MARS, PEX and PAP, since current guidelines do not specify which method is the most appropriate and under which circumstances it should be used. The choice of technique cannot be based on the desired plasma bilirubin concentration, since these three techniques show similar results with a similar final outcome (exitus). In fact, PAP, PEX and MARS significantly reduce bilirubin levels, but the degree of reduction is not different among the three. Furthermore, the three techniques do not differ in the rate of cholinesterase change, while less reduction of liver transaminases was found by using PAP. MARS should be preferred in the case of renal involvement (hepatorenal syndrome with hyperbilirubinemia). PAP has the advantage of being simple and inexpensive. PEX remains an option when emergency PAP is not available, but the risk of using blood products (plasma and albumin) must be considered.

[Examination of Urinary Sediment in a Patient with Lupus-Like HIV-Associated Immune Complex Kidney Disease (HIVICK) - Case Report and Review of the Literature]

Renal involvement is very common in patients with HIV infection. The phenotype varies from the most frequently "collapsing" variant of focal and segmental glomerulosclerosis (FSGS) to "lupus-like HIV-immune complex kidney disease" (HIVICK). The latter is characterized by a histological picture that recalls lupus nephropathy. Through a clinical case, we underline the importance of urinary sediment analysis in patients with suspected glomerulopathy. Findings such as the characteristic cells that show the typical appearance of Herpes virus (HSV) infection or LE cells have significantly supported the diagnosis of HIVICK. In light of the present observations, we suggest systematically carrying out a cytological examination of the urinary sediment to confirm diagnostic hypotheses of rare pathologies.

miR-218 Promotes Dopaminergic Differentiation and Controls Neuron Excitability and Neurotransmitter Release through the Regulation of a Synaptic-Related Genes Network

In the brain, microRNAs (miRNAs) are believed to play a role in orchestrating synaptic plasticity at a higher level by acting as an additional mechanism of translational regulation, alongside the mRNA/polysome system. Despite extensive research, our understanding of the specific contribution of individual miRNA to the function of dopaminergic neurons (DAn) remains limited. By performing a dopaminergic-specific miRNA screening, we have identified miR-218 as a critical regulator of DAn activity in male and female mice. We have found that miR-218 is specifically expressed in mesencephalic DAn and is able to promote dopaminergic differentiation of embryonic stem cells and functional maturation of transdifferentiated induced DA neurons. Midbrain-specific deletion of both genes encoding for miR-218 (referred to as miR-218-1 and mir218-2) affects the expression of a cluster of synaptic-related mRNAs and alters the intrinsic excitability of DAn, as it increases instantaneous frequencies of evoked action potentials, reduces rheobase current, affects the ionic current underlying the action potential after hyperpolarization phase, and reduces dopamine efflux in response to a single electrical stimulus. Our findings provide a comprehensive understanding of the involvement of miR-218 in the dopaminergic system and highlight its role as a modulator of dopaminergic transmission.SIGNIFICANCE STATEMENT In the past decade, several miRNAs have emerged as potential regulators of synapse activity through the modulation of specific gene expression. Among these, we have identified a dopaminergic-specific miRNA, miR-218, which is able to promote dopaminergic differentiation and regulates the translation of an entire cluster of synapse related mRNAs. Deletion of miR-218 has notable effects on dopamine release and alters the intrinsic excitability of dopaminergic neurons, indicating a direct control of dopaminergic activity by miR-218.

Mechanisms of Diabetic Nephropathy Not Mediated by Hyperglycemia

Diabetes mellitus (DM) is characterized by the appearance of progressive kidney damage, which may progress to end-stage kidney disease. The control of hyperglycemia is usually not sufficient to halt this progression. The kidney damage is quantitatively and qualitatively different in the two forms of diabetes; the typical nodular fibrosis (Kimmelstiel Wilson nodules) appears mostly in type 1 DM, whereas glomerulomegaly is primarily present in type 2 obese DM. An analysis of the different metabolites and hormones in type 1 and type 2 DM and their differential pharmacological treatments might be helpful to advance the hypotheses on the different histopathological patterns of the kidneys and their responses to sodium/glucose transporter type 2 inhibitors (SGLT2i).

Wall Tension and Tubular Resistance in Kidney Cystic Conditions

The progressive formation of single or multiple cysts accompanies several renal diseases. Specifically, (i) genetic forms, such as adult dominant polycystic kidney disease (ADPKD), and (ii) acquired cystic kidney disease (ACKD) are probably the most frequent forms of cystic diseases. Adult dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by multiple kidney cysts and systemic alterations. The genes responsible for the condition are known, and a large amount of literature focuses on the molecular description of the mechanism. The present manuscript shows that a multiscale approach that considers supramolecular physical phenomena captures the characteristics of both ADPKD and acquired cystic kidney disease (ACKD) from the pathogenetic and therapeutical point of view, potentially suggesting future treatments. We first review the hypothesis of cystogenesis in ADPKD and then focus on ACKD, showing that they share essential pathogenetic features, which can be explained by a localized obstruction of a tubule and/or an alteration of the tubular wall tension. The consequent tubular aneurysms (cysts) follow Laplace's law. Reviewing the public databases, we show that ADPKD genes are widely expressed in various organs, and these proteins interact with the extracellular matrix, thus potentially modifying wall tension. At the kidney and liver level, the authors suggest that altered cell polarity/secretion/proliferation produce tubular regions of high resistance to the urine/bile flow. The increased intratubular pressure upstream increases the difference between the inside (Pi) and the outside (Pe) of the tubules (∆P) and is counterbalanced by lower wall tension by a factor depending on the radius. The latter is a function of tubule length. In adult dominant polycystic kidney disease (ADPKD), a minimal reduction in the wall tension may lead to a dilatation in the tubular segments along the nephron over the years. The initial increase in the tubule radius would then facilitate the progressive expansion of the cysts. In this regard, tubular cell proliferation may be, at least partially, a consequence of the progressive cysts' expansion. This theory is discussed in view of other diseases with reduced wall tension and with cysts and the therapeutic effects of vaptans, somatostatin, SGLT2 inhibitors, and potentially other therapeutic targets.

A Reanalysis of Historical Figures With Depression and Dropsy

OBJECTIVES

Recent studies suggest a link between chronic kidney disease and brain dysfunctions such as depression and cognitive problems. A review of medieval and early-modern historical figures with aspects of both kidney disease (gout and edema [dropsy]) and depression (melancholia) shows that these conditions were observed together in the past.

MATERIALS AND METHODS

References to the diseases of gout, dropsy, and melancholia were compared in literature on historical subjects. Case studies are reported to detail a previously unremarked com-bination of current kidney disease and depression comorbidity in historical writings.

RESULTS

The poet Boccaccio had gout and melancholia, and some descendants of the Portuguese Avis and Spanish Trastàmara dynasties, known for melancholia and madness, also had gout and dropsy. Historical case series of causes of death for sultans of the Ottoman Empire suggest an association among dropsy, gout, and melancholia.

CONCLUSIONS

In this article, we reviewed the medical research on the comorbidity of kidney disease and depression and shared case studies of historical figures with these conditions and posit not previously noted data supporting comorbidity observations in historical writings.

[Anti-MBG crescentic glomerulonephritis with negative immunofluorescence: case report and literature review]

Anti-glomerular basement membrane (anti-GBM) antibody disease is a rapidly progressive glomerulonephritis characterized by (i) positivity to anti-GBM in serum reacting with a specific antigen present in type IV collagen at both the glomerular and alveolar levels (ii) presence of crescent on light microscopy and positivity to linear deposits of IgG and C3 on immunofluorescence. In the classic variant, the clinic is that of a nephro-pneumological syndrome but there are variants. Rarely, the glomerular damage is pauci-immune. We describe a case of a variant in which there is anti-MBG positivity in serum but negative immunofluorescence and offer a review of the literature and potential treatments.

Phosphate in the Context of Cognitive Impairment and Other Neurological Disorders Occurrence in Chronic Kidney Disease

The nervous system and the kidneys are linked under physiological states to maintain normal body homeostasis. In chronic kidney disease (CKD), damaged kidneys can impair the central nervous system, including cerebrovascular disease and cognitive impairment (CI). Recently, kidney disease has been proposed as a new modifiable risk factor for dementia. It is reported that uremic toxins may have direct neurotoxic (astrocyte activation and neuronal death) and/or indirect action through vascular effects (cerebral endothelial dysfunction, calcification, and inflammation). This review summarizes the evidence from research investigating the pathophysiological effects of phosphate toxicity in the nervous system, raising the question of whether the control of hyperphosphatemia in CKD would lower patients’ risk of developing cognitive impairment and dementia.

AB0463 PREVALENCE AND PREDICTORS OF COGNITIVE DYSFUNCTION IN PATIENTS WITH LUPUS NEPHRITIS: A CROSS-SECTIONAL COMPARISON WITH PATIENTS WITH OTHER CHRONIC KIDNEY DISEASES

Background

Cognitive dysfunction (CD) is among the most frequent neuropsychiatric manifestation of systemic lupus erythematosus (SLE) that has a considerable impact on quality of life, but still lacks adequate screening in clinical routine.

Objectives

Our aim was to investigate the distribution and determinants of CD in patients with lupus nephritis, and to compare cognitive function with that in patients with other forms of glomerular chronic kidney disease (CKD) by the Montréal Cognitive Assessment (MoCA).

Methods

We carried out a cross-sectional case-control study with consecutive patients with SLE who fulfilled the 2012 SLICC (Systemic Lupus International Collaborating Clinics) classification criteria(1) and have history of lupus nephritis, using a similarly derived CKD control population matched by age and sex, to assess cognitive function using MoCA scale(2). CD was defined as score < 26/30, adjusted for duration of formal education. Demographic data and disease characteristics were collected. SLE disease activity was evaluated by using Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI2K) (3). The effect of disease-related parameters on the MoCA was examined by regression analysis.

Results

A total of 35 patients with SLE and 35 CKD controls were included in our study (Table 1). Among SLE patients, 7 (20%) patients had biopsy proven active nephritis, 7 (20%) had kidney failure and one a kidney transplant. CD according to MoCA score was found in 64.2% (n=45) patients (Figure 1). The proportion of patients with CD according to MoCA between patients with lupus nephritis and CKD controls was not statistically significant (62.8% vs 65.7%, p>0.05). SLE patients performed bad in all cognitive domains. Memory, abstraction and language skills were the most affected domains. Our study showed that active nephritis and disease duration were associated with poor cognitive performance (OR=1.4, p = 0.03; OR=1.2, p = 0.03). GFR values and other parameters evaluated (end stage renal disease, damage, age at diagnosis, use of glucocorticoids, hydroxychloroquine and immunosuppressive drugs) had no significant effect on development of CD in SLE patients.

Table 1.

Demographics and clinical characteristics of SLE patients

mean%Age44Women94.2Education>16 yrs51.416 -13 yrs37.1<13 yrs11.4Disease duration (yrs)16Kidney failure20Prednisone (% use)<20 mg11.4≥20mg88.5Hydroxychloroquine (% use)65.7Immunosuppressants (% use)57.1SLEDAI2.4SDI0.8Figure 1.

Montréal Cognitive Assessment (MoCA) results in patients with systemic lupus erythematosus (SLE) compared to hemodialysis and chronic kidney disease (CKD) patients.

Conclusion

In this study, two thirds of SLE patients had CD. Patients with lupus nephritis have comparable cognitive function than patients with other CKD. Decline in renal function was not associated with CD in SLE, suggesting that the CD in this population may represent a consequence of lupus itself rather than kidney-related central nervous system damage.

References

[1]Petri M, et al. Arthritis Rheum. 2012

[2]Nasreddine ZS, et al. J Am Geriatr Soc 2005

[3]Gladman DD, et al. J Rheumatol. 2002

Disclosure of Interests

None declared

A Shared Nephroprotective Mechanism for Renin-Angiotensin-System Inhibitors, Sodium-Glucose Co-Transporter 2 Inhibitors, and Vasopressin Receptor Antagonists: Immunology Meets Hemodynamics

A major paradigm in nephrology states that the loss of filtration function over a long time is driven by a persistent hyperfiltration state of surviving nephrons. This hyperfiltration may derive from circulating immunological factors. However, some clue about the hemodynamic effects of these factors derives from the effects of so-called nephroprotective drugs. Thirty years after the introduction of Renin-Angiotensin-system inhibitors (RASi) into clinical practice, two new families of nephroprotective drugs have been identified: the sodium-glucose cotransporter 2 inhibitors (SGLT2i) and the vasopressin receptor antagonists (VRA). Even though the molecular targets of the three-drug classes are very different, they share the reduction in the glomerular filtration rate (GFR) at the beginning of the therapy, which is usually considered an adverse effect. Therefore, we hypothesize that acute GFR decline is a prerequisite to obtaining nephroprotection with all these drugs. In this study, we reanalyze evidence that RASi, SGLT2i, and VRA reduce the eGFR at the onset of therapy. Afterward, we evaluate whether the extent of eGFR reduction correlates with their long-term efficacy. The results suggest that the extent of initial eGFR decline predicts the nephroprotective efficacy in the long run. Therefore, we propose that RASi, SGLT2i, and VRA delay kidney disease progression by controlling maladaptive glomerular hyperfiltration resulting from circulating immunological factors. Further studies are needed to verify their combined effects.

Chronic kidney disease and neurological disorders: are uraemic toxins the missing piece of the puzzle?

Chronic kidney disease (CKD) perturbs the crosstalk with others organs, with the interaction between the kidneys and the heart having been studied most intensively. However, a growing body of data indicates that there is an association between kidney dysfunction and disorders of the central nervous system. In epidemiological studies, CKD is associated with a high prevalence of neurological complications, such as cerebrovascular disorders, movement disorders, cognitive impairment and depression. Along with traditional cardiovascular risk factors (such as diabetes, inflammation, hypertension and dyslipidaemia), non-traditional risk factors related to kidney damage (such as uraemic toxins) may predispose patients with CKD to neurological disorders. There is increasing evidence to show that uraemic toxins, for example indoxyl sulphate, have a neurotoxic effect. A better understanding of factors responsible for the elevated prevalence of neurological disorders among patients with CKD might facilitate the development of novel treatments. Here, we review (i) the potential clinical impact of CKD on cerebrovascular and neurological complications, (ii) the mechanisms underlying the uraemic toxins' putative action (based on pre-clinical and clinical research) and (iii) the potential impact of these findings on patient care.

Brain dysfunction in tubular and tubulointerstitial kidney diseases

Kidney function has two important elements: glomerular filtration and tubular function (secretion and reabsorption). A persistent decrease in glomerular filtration rate (GFR), with or without proteinuria, is diagnostic of chronic kidney disease (CKD). While glomerular injury or disease is a major cause of CKD and usually associated with proteinuria, predominant tubular injury, with or without tubulointerstitial disease, is typically non-proteinuric. CKD has been linked with cognitive impairment, but it is unclear how much this depends on a reduced GFR, altered tubular function or the presence of proteinuria. Since CKD is often accompanied by tubular and interstitial dysfunction, we explore here for the first time the potential role of the tubular and tubulointerstitial compartments in cognitive dysfunction. To help address this issue, we have selected a group of primary tubular diseases with preserved GFR, in which to review the evidence for any association with brain dysfunction. Cognition, mood, neurosensory, and motor disturbances are not well characterized in tubular diseases, possibly because they are subclinical and less prominent than other clinical manifestations. The available literature suggests that brain dysfunction in tubular and tubulointerstitial diseases is usually mild and is more often seen in disorders of water handling. Brain dysfunction may occur when severe electrolyte and water disorders in young children persist over a long period of time before the diagnosis is made. We have chosen as examples to highlight this topic, Bartter and Gitelman syndromes and nephrogenic diabetes insipidus. We discuss current published findings, some unanswered questions, and propose topics for future research.

Neuropeptide Y as a risk factor for cardiorenal disease and cognitive dysfunction in CKD: translational opportunities and challenges

Neuropeptide Y (NPY) is a 36-amino-acid peptide member of a family also including peptide YY and pancreatic polypeptide, which are all ligands to Gi/Go coupled receptors. NPY regulates several fundamental biologic functions including appetite/satiety, sex and reproduction, learning and memory, cardiovascular and renal function and immune functions. The mesenteric circulation is a major source of NPY in the blood in man and this peptide is considered a key regulator of gut–brain cross talk. A progressive increase in circulating NPY accompanies the progression of chronic kidney disease (CKD) toward kidney failure and NPY robustly predicts cardiovascular events in this population. Furthermore, NPY is suspected as a possible player in accelerated cognitive function decline and dementia in patients with CKD and in dialysis patients. In theory, interfering with the NPY system has relevant potential for the treatment of diverse diseases from cardiovascular and renal diseases to diseases of the central nervous system. Pharmaceutical formulations for effective drug delivery and cost, as well as the complexity of diseases potentially addressable by NPY/NPY antagonists, have been a problem until now. This in part explains the slow progress of knowledge about the NPY system in the clinical arena. There is now renewed research interest in the NPY system in psychopharmacology and in pharmacology in general and new studies and a new breed of clinical trials may eventually bring the expected benefits in human health with drugs interfering with this system.

Cognitive disorders in patients with chronic kidney disease: specificities of clinical assessment

Neurocognitive disorders are frequent among chronic kidney disease (CKD) patients. Identifying and characterizing cognitive impairment (CI) can help to assess the ability of adherence to CKD risk reduction strategy, identify potentially reversible causes of cognitive decline, modify pharmacotherapy, educate the patient and caregiver and provide appropriate patient and caregiver support. Numerous factors are associated with the development and progression of CI in CKD patients and various conditions can influence the results of cognitive assessment in these patients. Here we review clinical warning signs that should lead to cognitive screening; conditions frequent in CKD at risk to interfere with cognitive testing or performance, including specificities of cognitive assessment in dialysis patients or after kidney transplantation; and available tests for screening and observed cognitive patterns in CKD patients.

Urine concentrating defect as presenting sign of progressive renal failure in Bardet-Biedl syndrome patients

BACKGROUND

Urine concentrating defect is a common dysfunction in ciliopathies, even though its underlying mechanism and its prognostic meaning are largely unknown. This study assesses renal function in a cohort of 54 Bardet-Biedl syndrome (BBS) individuals and analyses whether renal hyposthenuria is the result of specific tubule dysfunction and predicts renal disease progression.

METHODS

The estimated glomerular filtration rate (eGFR), urine albumin:creatinine ratio (ACR) and maximum urine osmolality (max-Uosm) were measured in all patients. Genetic analysis was conducted in 43 patients. Annual eGFR decline (ΔeGFR) was measured in patients with a median follow-up period of 6.5 years. Urine aquaporin-2 (uAQP2) excretion was measured and the furosemide test was performed in patients and controls.

RESULTS

At baseline, 33 (61.1%), 12 (22.2%) and 9 (16.7%) patients showed an eGFR >90, 60-90 and <60 mL/min/1.73 m2, respectively; 27.3% showed an ACR >30 mg/g and 55.8% of patients showed urine concentrating defect in the absence of renal insufficiency. Baseline eGFR, but not max-Uosm, correlated negatively with age. Conversely, truncating mutations affected max-Uosm and showed a trend towards a reduction in eGFR. Max-Uosm correlated with ΔeGFR (P < 0.005), suggesting that urine concentrating defect may predict disease progression. uAQP2 excretion and Na+ and Cl- fractional excretion after furosemide did not differ between hyposthenuric patients and controls, suggesting that specific collecting duct and thick ascending limb dysfunctions are unlikely to play a central role in the pathogenesis of hyposthenuria.

CONCLUSIONS

Hyposthenuria is a warning sign predicting poor renal outcome in BBS. The pathophysiology of this defect is most likely beyond defective tubular function.

MO354PRELIMINARY EVIDENCE OF RIVASTIGMINE EFFICACY IN CKD RELATED MILD COGNITIVE IMPAIRMENT

Background and Aims

Mild Cognitive Impairment (MCI) is a common finding in chronic kidney disease (CKD) patients. Indeed, CKD represents a relevant risk factor for developing dementia and MCI. Cholinesterase inhibitors, such as rivastigmine, are among the few drugs approved for the treatment of dementia and MCI. Rivastigmine is also used to treat vascular dementia because it protects subcortical brain structures. Data are scanty regarding the use of rivastigmine in CKD patients with MCI and are much needed to guide the therapy for MCI in this cohort of patients.

Method

This retrospective case-control study compared the effects of rivastigmine on cognitive functions in MCI patients with CKD (stage III-IV; n= 20) and without CKD (n=21, control group), comparable for the extent of cognitive impairment (indexed by Montreal Cognitive Assessment, MoCA), age (range 18-65 years), gender, weight, and comorbidities. Patients under treatment with rivastigmine and with a baseline MoCA score available were included in the study. Exclusion criteria were ictus, psychiatric or other neurological conditions, heart failure, liver failure, severe obesity, anemia, electrolyte disorders, cancer, dialysis, and other severe comorbidities. Laboratory test data (glycemia, cholesterol, hemoglobin, proteinuria, creatinine) were used to characterize the two populations. MCI was defined as a MoCA score between 21-26. The cognitive screening was available at baseline (before treatment) and during a follow-up in a range of three-six months after the start of the treatment. CKD was defined by eGFR &lt; 60 mL/min/1.73m2.

Results

The follow-up timing for cognitive screening was not statistically different between the two cohorts. The control group (MCI without CKD) showed a small, significant improvement in the MoCA score after treatment (baseline MoCA: 22.9±0.5, follow-up MoCA: 23.5±0.5, p=0.02, t-test for paired data).

At variance, the MCI-CKD group showed a significant improvement in the MoCA score (baseline MoCA=23±0.4, follow-up MoCA=24.3±0.4, p&lt;0.05).

Accordingly, the extent of improvement of MoCA score after rivastigmine was inversely correlated to the eGFR (r = -0.23).

Conclusion

A significant improvement in MoCA score accompanied treatment with rivastigmine in the CKD group. More extensive population studies are needed to verify the greater efficacy of Acetylcholinesterase inhibitors in this population.

MO1032HISTORY OF THE PARADIGMS OF INFLAMMATION IN KIDNEY DISEASES

Background and Aims

The term "inflammation" is undoubtedly one of the oldest medical terms and yet in use. However, its meaning has changed over the centuries. This work gives a historical and critical view of the concept of inflammation, with particular reference to kidney diseases.

Method

The term "inflammation" was used in Galenic medicine to specify a collection of symptoms. Celsus (c. 25 BC – c. 50 AD) described "rubor et tumor cum calor et dolor", but the list became much longer in subsequent Galenic scholars. It is interesting to note that one of the inflammation symptoms, "tumor," was then used to indicate cancer (tumor=swelling due to a mass or due to edema). Virchow (1821 –1902) is often quoted for introducing a fifth symptom, "function Lasa", but his significant contribution relies on introducing the microscope to study diseases: thanks to this instrument, the paradigm of inflammation was undergoing a revolution. Thereby, the definition of inflammation shifted from a pure collection of symptoms to a histopathological classification, characterized by the tissue "inflammatory infiltrates" with subcategories according to the cell types involved. Numerous authors added their names to pathology textbooks when describing a new kind of cellular infiltration.

Overall, the tremendous success of the histopathologic paradigm of inflammation or "inflammatory infiltrates" was the possibility to contain and revert this phenomenon with corticosteroids (with few exceptions). Subsequently, specific drugs were proposed for each inflammatory infiltrate. This type of paradigm is still used today to define, e.g., tubulointerstitial nephritis or intra- and peri-glomerular inflammations. The subsequent classification of inflammatory infiltrates using immunohistochemistry did not modify our classification system (the distinction of, e.g., CD20 lymphocytes from CD4 T-cells is not used, unfortunately, in today's classification system).

Results

Towards the 1940s, Avery et al. recognize that some plasma proteins (specifically the famous C-reactive protein) increase during acute infection, which is a typical inflammatory state. This observation led to a new "molecular definition of inflammation". The idea to identify the presence of inflammatory infiltrates in tissues just by looking at plasma constituents had great success: after all, the histological processing of tissues was no longer needed. Even though many authors were alerting that these plasma constituents are often increased even in the absence of any "inflammatory infiltrate", the plasma proteins were so easily accessible that the new direction was not modifiable.

A modern generalization of this type of approach is called "liquid biopsy, " even though it is not limited to the inflammatory states, but to a larger number of identifiable diseases today only histologically.

The effect of the new "molecular" definition of inflammation was that a large number of diseases without significant inflammatory infiltrates (such as obesity, atherosclerosis, aging, dialysis, and chronic kidney disease) are notwithstanding accompanied by the increase of plasma proteins labeled as "inflammatory". Therefore, the list of "inflammatory" diseases (in the new terms) is now much more extensive. The price for such enlargement of conditions is that most new entries do not respond to steroids or other anti-inflammatory drugs.

Conclusion

The new definition of" inflammatory disease" comprises classical steroid-dependent disorders characterized by inflammatory infiltrates and new conditions with minimal inflammatory infiltrates plus the presence of "inflammatory" plasma proteins plus little response to steroids. It might be beneficial to distinguish these types of inflammation.

MO035COMPUTATIONAL MODELING APPROACH FOR THE COMPREHENSIVE INTERPRETATION OF RARE TUBULOPATHIES

Background and Aims

Kidney plays a central role on the maintenance of water homeostasis, acid-base and electrolytes balances through the activity of different types of ion channels/transporters expressed along the nephron segments. Mutations in genes encoding these transporters could subsequently lead to aberrant transporter activities, resulting in abnormal renal handling of electrolytes, thus represent monogenic form of rare kidney diseases.

Accumulating number of mutations identified in genes responsible for such monogenic disorders demonstrated that eventual disease phenotypes may vary according to the type and localization of the mutation within the gene. Thus, careful evaluation of gene variation would be crucial prior to designing the strategy for the therapy in each case.

Here we present various mutations from our patients, identified in genes including kcnj10, SLC12A1, SLC26A4 and clcn7 which are associated with rare tubulopathies EAST/SeSAME syndrome, Bartter’s syndrome, Pendred syndrome and Fanconi syndrome, respectively.

In order to explore molecular mechanisms underlying the observed disease conditions in our patients, we have performed computational modeling analyses of these mutations in comparison with wild-type models.

Method

Three-dimensional homology models of Kir4.1, NKCC2, Pendrin and CLC-7 proteins were generated by Swiss-Model protein structure homology-modelling server (http://swissmodel. expasy.org) and I-TASSER server (https://zhanglab.ccmb.med.umich.edu/I-TASSER/). Disease-related mutations including novel mutations identified from our patients were mapped onto the three-dimensional models and compared with wild-type models in terms of atomic interactions as well as secondary, tertiary and quaternary structures. Furthermore, we assessed possible effects of missense mutations on the function of ion channels/transporters using online bioinformatic prediction tools PolyPhen-2, Mutation taster, PROVEAN and SIFT.

Results

The three-dimensional model comparison between wild-type Kir4.1 and Ala167Val variant, which is related to EAST/SeSAME syndrome, revealed that Ala167Val located at the junction between transmembrane domain 2 (TM2) and C-terminus is predicted not to interrupt the sequence of the hydrogen bonds, thus not altering the TM2 alpha-helix structure. In addition, while PolyPhen-2 and Mutation taster evaluated Ala167Val as ‘probably damaging’, PROVEAN and SIFT predicted Ala167Val as ‘neutral’ and ‘tolerated’. These observations are in line with the clinical data demonstrating the milder phenotype in patients with Ala167Val mutation compared with the ones harboring frameshift mutations leading to truncated Kir4.1 channel (Figure. 1).

Furthermore, computational modeling of wild-type NKCC2 and frameshift mutation Arg302Glyfs*3 variant clearly demonstrated that Arg302Glyfs*3 results in a loss of large part of the protein, indicating that NKCC2-Arg302Glyfs*3 is practically nonfunctional (Figure. 2).

Conclusion

Computational modeling of disease-related mutations in various ion channels/transporters represents a novel, powerful approach for comprehensive interpretation of the disease phenotypes observed in patients with rare tubulopathies. In addition, combination of in silico modeling and clinical data could provide us with further insight into molecular mechanisms underlying the renal transporter activities. Furthermore, this in silico computational modeling approach can be applicable and suggestive for novel pharmacological intervention as well as the visual disease severity assessment.

MO227RELATIONSHIP BETWEEN KIDNEY DAMAGE AND COGNITIVE FUNCTIONS IN PATIENTS WITH GLOMERULOPATHIES

Background and Aims

Mild Cognitive Impairment (MCI) has been found to be highly prevalent amongst patients with Chronic Kidney Disease (CKD). In this cohort, the prevalence of MCI was estimated to be between 30% and 63%. Mild cognitive impairment is an intermediate state between normal aging and dementia. An individual suffering from MCI has difficulty in remembering, sustaining attention, or decision making which can negatively affect their daily lives.

The aim of this study was to verify the role of different glomerular diseases diagnosed by kidney biopsy on the MCI through a retrospective study.

Method

We recruited 45 patients with bioptic diagnosis of the following glomerular diseases: Focal Segmental Glomerulo Sclerosis (FSGS), minimal change disease (MCD), membranous glomerular disease (MG), IgA nephropathy. The renal function was analyzed using clinical variables, while Cognitive functions using the MoCA test. Patients were divided into two groups based on 24h proteinuria.

Results

The MoCA score was directly correlated to the uric acid levels (R=0.13; p=0.03). The MoCa score in the group with higher proteinuria levels was significantly lower than those of the group with lower proteinuria levels (p = 0.03). Finally, the MoCA score in subjects with FSGS or MCD is significantly higher compared the other groups (p&lt;0.05).

Conclusion

Our data suggest that serum uric acid and proteinuria in glomerular diseases influence cognitive functions. Interestingly, uric acid plays a neuroprotective role, as low levels of uric acid reduce the MoCA score. This result agrees with previous observations of a protective role of uric acid on dopamine neurons. Conversely, the extent proteinuria seems to negatively affect cognitive functions, suggesting a role of the endothelial dysfunction. Finally, glomerulopathies with a lower degree of inflammation (FSGS, MCD) have minor impact on cognitive functions.

MO216PRELIMINARY STUDY OF THE GLYMPHATIC SYSTEM IN CKD

Background and Aims

The glymphatic system is a network of extracellular spaces between neurons, glial cells, and capillaries that promotes the elimination of soluble molecules from the brain. Its dysfunction is probably relevant for neurodegenerative diseases such as Alzheimer's disease (AD). It is widely accepted that cognitive impairment accompanies chronic kidney disease (CKD). CKD is also a risk factor for dementia. However, the role of the glymphatic system in this process is unknown. A recent method to study the glymphatic system in human subjects has been proposed based on Diffusion Tensor Imaging (DTI) data and water diffusion calculation along with perivascular spaces. This approach is based on calculating a diffusion index named ALPS and showed that the glymphatic flow is reduced in MCI.

Method

To analyze the role of glymphatic system in CKD patients, we took advantage of the Alzheimer's Disease Neuroimaging Initiative (ADNI). ADNI is a longitudinal multicenter study helping researchers to monitor Alzheimer's disease and Mild Cognitive Impairment (MCI) progression. This database has a cohort of control patients and MCI patients, among which several patients with CKD stage II-III were identifiable from the creatinine values. Patients with Alzheimer's disease were excluded for this study. Among the control and MCI patients, we identified 12 CKD patients and pair-matched 12 non-CKD patients comparable for age, gender, and MoCA score. Magnetic resonance data with DTI sequences were retrieved for all patients, and the glymphatic system was characterized by the ALPS index. Tensor values were calculated using the FSL software; the diffusion values were calculated on tensor images using the ImageJ software. Differences in ALPS between CKD and non-CKD patients with and without MCI were tested.

Results

Analysis of DTI data confirmed that control patients without CKD had lower ALPS values when MCI was present compared to the non-MCI patients, suggesting a reduction of water diffusion in the glymphatic system. However, the presence of CKD had a different effect: in the absence of MCI, CKD did not modify ALPS values compared to non-CKD patients. At variance, in patients with MCI, CKD resulted in a significant increase of water diffusion in the glymphatic system compared to the controls.

Conclusion

In this preliminary study, MCI and CKD exerted opposite effects on the diffusion of water within the glymphatic system: MCI was accompanied by a reduction of water diffusion whereas CKD by an increased diffusion in the glymphatic spaces.

It is possible that small modification of water balance in CKD may be responsible for the increased diffusion of water in glymphatics in CKD. Further studies are needed to verify whether this unexpected phenomenon may modify cognitive function with a mechanism rather different from Alzheimer's disease.

Dopamine: The Neuromodulator of Long-Term Synaptic Plasticity, Reward and Movement Control

Dopamine (DA) is a key neurotransmitter involved in multiple physiological functions including motor control, modulation of affective and emotional states, reward mechanisms, reinforcement of behavior, and selected higher cognitive functions. Dysfunction in dopaminergic transmission is recognized as a core alteration in several devastating neurological and psychiatric disorders, including Parkinson's disease (PD), schizophrenia, bipolar disorder, attention deficit hyperactivity disorder (ADHD) and addiction. Here we will discuss the current insights on the role of DA in motor control and reward learning mechanisms and its involvement in the modulation of synaptic dynamics through different pathways. In particular, we will consider the role of DA as neuromodulator of two forms of synaptic plasticity, known as long-term potentiation (LTP) and long-term depression (LTD) in several cortical and subcortical areas. Finally, we will delineate how the effect of DA on dendritic spines places this molecule at the interface between the motor and the cognitive systems. Specifically, we will be focusing on PD, vascular dementia, and schizophrenia.

Regulation of urinary calcium excretion by vasopressin

Background

The antidiuretic hormone (ADH) or arginine vasopressin (AVP) regulates the body's water balance. Recently, modifications in AVP levels have been related to osteoporosis during ageing and microgravity/bed rest. Therefore the present study was devised to assess whether the absence of AVP, as in patients with central diabetes insipidus (CDI), modulates renal calcium excretion.

Methods

We retrospectively analysed data from 12 patients with CDI with measured 24-h urinary excretion levels of calcium. Data were available at the moment of the diagnosis when patients were drug-free and after therapy with dDAVP, an analog of AVP. Hypercalciuria was defined as 24-h urinary Ca²⁺ >275 mg/day in males and >250 mg/day in females and a urinary calcium (Ca):creatinine (Cr) ratio >0.20 mg/mg.

Results

Untreated CDI patients had a daily urinary Ca²⁺ excretion of 383 ± 47 mg/day and a urinary Ca:Cr ratio of 0.26 ± 0.38 mg/mg. The urine osmolarity significantly increased after the administration of dDAVP by 210% and the urinary flow decreased by 72%. Furthermore, the estimated glomerular filtration rate (eGFR) increased by 7%, which did not reach statistical significance. dDAVP treatment did not significantly modify the urinary Ca²⁺ concentration; however, the daily calcium excretion and the urinary Ca:Cr ratio were significantly decreased (160 ± 27 mg/day and 0.11 ± 0.02 mg/mg, respectively).

Conclusions

Patients with CDI show hypercalciuria even though urine is more diluted than normal controls, and dDAVP reverses this effect. These data support the intriguing relationship between AVP and osteoporosis in ageing and microgravity/bed rest.

Skin Architecture, Kidney Transplantation, and Their Relationship to Basal and Squamous Cell Carcinomas

BACKGROUND/AIM

Squamous cell carcinoma (SCC) is highly prevalent in kidney transplant patients (KT). It is characterized by the presence of an inflammatory infiltrate. In this study, we examined the presence of similar infiltrates in intact skin, which could be regarded as a precancerous step.

PATIENTS AND METHODS

We retrospectively analyzed skin biopsies of 19 non-transplanted patients with a diagnosis of SCC or basal cell carcinoma (BCC) and 17 KT with either SCC or BCC.

RESULTS

KT showed increased inflammatory infiltrate in the subepithelial region, compared to non-transplanted patients. The density of basal cell nuclei was also different among the four groups with an interaction effect between tumor type and transplantation. The extent of inflammatory infiltrates did not correlate with the eGFR and proteinuria.

CONCLUSION

KT with a non-melanoma skin cancer show increased intact skin inflammatory infiltrate and alterations in the density of the basal cell layer compared to non-transplanted patients.

[Inflammation in kidney diseases]

The term "inflammation" is certainly one of the oldest medical terms still in use. However, its meaning has changed over the centuries. This work gives a historical and critical review of the concept of inflammation, with special reference to kidney diseases. Over time the definition of inflammation has shifted from a pure collection of symptoms to a histopathological definition, characterized by the tissue "inflammatory infiltrates" and different subcategories according to the cell type involved. The advantages of this classification are the generally good response to corticosteroids (with only a few exceptions) and the availability of specific drugs for each inflammatory infiltrate. Finally, a "molecular" definition of inflammation has arisen, where the inflammatory infiltrates make room to a plethora of plasma mediators. The authors show that the use of plasma biomarkers as a tool to define inflammatory state leads to net inflation of the number of "inflammatory" diseases - an effect that shows clearly in the field of nephrology.

Kidney Transplant Modifies the Architecture and Microenvironment of Basal Cell Carcinomas

BACKGROUND/AIMS

Basal cell carcinoma (BCC) is a frequent type of nonmelanoma skin cancer, which shows a greater prevalence in kidney-transplanted (KT) patients than in the general population. The study of this tumor in KT patients may allow us to understand the influence of the tumor inflammatory microenvironment on cancer behavior, and to design new image analysis methods to determine prognosis and apply personalized medicine. The major hypothesis of the present work is that antirejection drugs, by modifying the B-cell/T-cell balance, induce measurable differences in tumoral cell microarchitecture and in the inflammatory microenvironment in KT patients compared to nontransplanted controls.

METHODS

In this retrospective study in an Italian cohort including 15 KT patients and 15 control subjects from the general population who developed BCC, we analyzed tissue microarchitecture and inflammatory infiltrates of BCC using state-of-the-art nonlinear image analysis techniques such as fractal dimension and sample entropy of internuclear distances.

RESULTS

KT patients showed a nonsignificant trend to a greater number of nuclei in the basal cell layer compared to non-KT controls and subtle changes in the intact skin compared to controls. Similarly, the number of mitoses per unit length was almost doubled in the patients with KT compared to controls. However, when the number of mitotic cells was normalized by the total number of cells in the basal layer (mitotic index), these differences were not significant, although a clear trend was still present. Finally, KT patients showed a nonsignificant trend to an increased -density of inflammatory cells close to the tumoral cell layer. When considering the intact skin, this difference was significant, with a 70% increase in the density of inflammatory cells.

CONCLUSION

Data comparing the microarchitecture of BCC in normal subjects and KT patients are scanty, and the present study is the first to use nonlinear image analysis techniques to this aim. The observed differences underscore the relevance of T-cell suppression in cancer behavior. These data suggest that BCC develops in treated patients with specific biological characteristics which should be further analyzed in terms of therapeutic response.

Molecular networks in Network Medicine: Development and applications

Network Medicine applies network science approaches to investigate disease pathogenesis. Many different analytical methods have been used to infer relevant molecular networks, including protein-protein interaction networks, correlation-based networks, gene regulatory networks, and Bayesian networks. Network Medicine applies these integrated approaches to Omics Big Data (including genetics, epigenetics, transcriptomics, metabolomics, and proteomics) using computational biology tools and, thereby, has the potential to provide improvements in the diagnosis, prognosis, and treatment of complex diseases. We discuss briefly the types of molecular data that are used in molecular network analyses, survey the analytical methods for inferring molecular networks, and review efforts to validate and visualize molecular networks. Successful applications of molecular network analysis have been reported in pulmonary arterial hypertension, coronary heart disease, diabetes mellitus, chronic lung diseases, and drug development. Important knowledge gaps in Network Medicine include incompleteness of the molecular interactome, challenges in identifying key genes within genetic association regions, and limited applications to human diseases. This article is categorized under: Models of Systems Properties and Processes > Mechanistic Models Translational, Genomic, and Systems Medicine > Translational Medicine Analytical and Computational Methods > Analytical Methods Analytical and Computational Methods > Computational Methods.

Mechanisms of cognitive dysfunction in CKD

Cognitive impairment is an increasingly recognized major cause of chronic disability and is commonly found in patients with chronic kidney disease (CKD). Knowledge of the relationship between kidney dysfunction and impaired cognition may improve our understanding of other forms of cognitive dysfunction. Patients with CKD are at an increased risk (compared with the general population) of both dementia and its prodrome, mild cognitive impairment (MCI), which are characterized by deficits in executive functions, memory and attention. Brain imaging in patients with CKD has revealed damage to white matter in the prefrontal cortex and, in animal models, in the subcortical monoaminergic and cholinergic systems, accompanied by widespread macrovascular and microvascular damage. Unfortunately, current interventions that target cardiovascular risk factors (such as anti-hypertensive drugs, anti-platelet agents and statins) seem to have little or no effect on CKD-associated MCI, suggesting that the accumulation of uraemic neurotoxins may be more important than disturbed haemodynamic factors or lipid metabolism in MCI pathogenesis. Experimental models show that the brain monoaminergic system is susceptible to uraemic neurotoxins and that this system is responsible for the altered sleep pattern commonly observed in patients with CKD. Neural progenitor cells and the glymphatic system, which are important in Alzheimer disease pathogenesis, may also be involved in CKD-associated MCI. More detailed study of CKD-associated MCI is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention, and whether there may be novel approaches and potential therapies with wider application to this and other forms of cognitive decline.

The number of nephrons in different glomerular diseases

Background

The total number of nephrons has been measured mainly from post-mortem studies and only in selected populations. Data from living subjects are scanty, and direct comparisons among different glomerular diseases are lacking. The present work exploits modern methodology to estimate the total nephron number in glomerulopathies with prevalent proteinuria/nephrotic syndrome versus glomerulopathies with nephritic syndrome (IgA nephropathy (IgAN), lupus nephritis), thus extending previous observations about the number and function of glomeruli in different physiological and pathological states.

Methods

This is a retrospective study based on one hundred and seven patients who have undergone renal biopsy. The glomerular density has been estimated from the biopsy specimens and the total cortical volume has been obtained from ultrasound recordings. Stereological methods have been applied to calculate the total number of nephrons and their volume. The correlation between clinical parameters and quantitative morphological data have studied using the Pearson correlation coefficient (r).

Results

The total number of nephrons inversely correlated with the systolic blood pressure (r = −0.4, p < 0.05). In proteinuric diseases, such as focal segmental glomerulo-sclerosis (FSGS), membranous nephropathy (MN) and diabetes, the change in estimated GFR (eGFR) directly correlated with the total number of non-sclerotic glomeruli (NSG) (r = 0.62, p < 0.01), whereas in nephritic syndrome no significant correlation was observed. The alterations in eGFR occurring in nephritic syndromes such as IgAN cannot be explained on the basis of the number of NSG.

Discussion

The fusion of the podocyte foot-processes that typically occurs in purely proteinuric diseases does not modify the glomerular filtration rate: therefore in these situations, the change in eGFR depends mainly on the number of available glomeruli. On the other side, the eGFR decrease occurring in nephritic syndromes, such as IgAN, cannot be explained simply on the basis of the number of NSG and likely depends on the substantial involvement of the mesangial axis. Future studies should verify whether these changes are reversible with appropriate therapy, thus reversing eGFR decrease.

Diuretic Resistance in Cardio-Nephrology: Role of Pharmacokinetics, Hypochloremia, and Kidney Remodeling

Background: Diuretic resistance is among the most challenging problems that the cardio-nephrologist must address in daily clinical practice, with a considerable burden on hospital admissions and health care costs. Indeed, loop diuretics are the first-line therapy to overcome fluid overload in heart failure patients. The pathophysiological mechanisms of fluid and sodium retention are complex and depend on several neuro-hormonal signals mainly acting on sodium reabsorption along the renal tubule. Consequently, doses and administration modalities of diuretics must be carefully tailored to patients in order to overcome under- or overtreatment. The frequent and tricky development of diuretic resistance depends in part on post-diuretic sodium retention, reduced tubular secretion of the drug, and reduced sodium/chloride sensing. Sodium and chloride depletions have been recently shown to be major factors mediating these processes. Aquaretics and high-saline infusions have been recently suggested in cases of hyponatremic conditions. This review discusses the limitations and strengths of these approaches. Summary: Long-term diuretic use may lead to diuretic resistance in cardio-renal syndromes. To overcome this complication intravenous administration of loop diuretics and a combination of different diuretic classes have been proposed. In the presence of hyponatremia, high-saline solutions in addition to loop diuretics might be beneficial, whereas aquaretics require caution to avoid overcorrection. Key Messages: Diuretic resistance is a central theme for cardio-renal syndromes. Hyponatremia and hypochloremia may be part of the mechanisms for diuretic resistance. Aquaretics and high-saline solutions have been proposed as possible new therapeutic solutions.

Preliminary results of autologous adipose-derived stem cells in early knee osteoarthritis: identification of a subpopulation with greater response

PURPOSE

The purpose of this study was to report the clinical and functional results of a series of patients with early knee osteoarthritis (KOA) treated with the intra-articular injection of autologous adipose-derived stem cells (aASCs) plus arthroscopic debridement. The hypothesis was that protocol would significantly improve the clinical and functional outcomes in patients with early KOA.

METHODS

Fifty-two patients with early KOA, who received arthroscopic debridement followed by percutaneous injection of aASCs, were enrolled into the study and retrospectively analyzed with an average follow-up of 15.3 (range, 6 to 24) months. Patients were assessed through the IKS knee and function scores and VAS pain scale.

RESULTS

The mean IKS knee score improved from 37.4 (range, 14 to 79) points pre-operatively to 62.6 (range, 27 to 95) points at the latest follow-up (p < < 0.01). The mean IKS function score improved from 57.2 (range, 25 to 100) points pre-operatively to 83.0 (range, 35 to 100) points at the latest follow-up (p < < 0.01). The mean VAS score decreased from 8.5 (range, 3 to 10) pre-operatively to 5.1 (range, 0 to 8) at the latest follow-up (p < < 0.01). Additionally, patients with a pre-operative VAS score greater than 8 were found to show greater clinical and functional benefits compared with patients with VAS score lower than 8.

CONCLUSIONS

The knee injection of aASCs associated to arthroscopic debridement increased significantly the clinical and functional scores in patients with early KOA at a mid-term follow-up, especially those with higher pre-operative VAS scores.

A cross-sectional study on the relationship between hematological data and quantitative morphological indices from kidney biopsies in different glomerular diseases

Background

The classical approach to the analysis of kidney biopsies is based on semi-quantitative scores of the amount of sclerosis, inflammatory infiltrate, fibrosis and vascular damage. However, advanced renal lesions may be accompanied by a paucity of clinical features and, conversely, important clinical abnormalities may be accompanied by minimal histopathological changes. The objective of this study is to correlate new, semiautomatic, quantitative features of kidney biopsies (e.g. fractal analysis) with clinical and hematological parameters using a cross-sectional design.

Methods

Whole slide images from sixty-seven biopsies of patients diagnosed for diabetic nephropathy, hypertensive nephropathy, focal segmental glomerulosclerosis (FSGS) or IgA nephropathy have been used. The images have been semi-automatically quantified in the ImageJ environment, in order to derive the glomerular density, the tubular density, the number of tubules per glomerulus and the fractal dimension of the tubular lumen in the cortex (an index of complexity of the tubular lumen). For each patient, hemato-chemical data have been retrieved, including the uric acid level and the creatinine-based eGFR.

Results

A linear relationship between eGFR and glomerular density was observed in hypertension and FSGS, but not in diabetic nephropathy. Conversely, the eGFR correlated with the tubular density across different glomerular conditions. Moreover, the tubular density was linearly correlated with uric acid levels in different pathological conditions. The fractal dimension of tubular lumen was correlated with the eGFR but only in hypertensive patients. Finally, blood pressure was not correlated to any of the morphological indices tested.

Conclusions

We propose the use of the fractal dimension as a new morphological descriptor of the nephron integrity.

A meta-analytic approach to genes that are associated with impaired and elevated spatial memory performance

Spatial memory deficits are a common hallmark of psychiatric conditions, possibly due to a genetic predisposition. Thus, unravelling the relationship between genes and memory might suggest novel therapeutic targets and pathogenetic pathways. Genetic deletions are known to lead to memory deficits (post-deletion "forgetfulness" genes, PDF), or, in few instances to improve spatial memory (post-deletion "hypermnesic" genes, PDH). To assess this topic, we performed a meta-analytic approach on memory behavior in knock-out mice. We screened 300 studies from PubMed and retrieved 87 genes tested for possible effects on spatial memory. This database was crossed with the Allen Brain Atlas (brain distribution) and the Enrichr (gene function) databases. The results show that PDF genes have higher expression level in several ventral brain structures, particularly the encephalic trunk and in the hypothalamus. Moreover, part of these genes are implicated in synaptic functions. Conversely, the PDH genes are associated to G-protein coupled receptors downstream signalling. Some candidate drugs were also found to interfere with some of the PDH genes, further suggesting that this approach might help in identifying drugs to improve memory performance in psychiatric conditions.