The Myth of Water and Salt: From Aquaretics to Tenapanor.

The impact of water intake has been studied in several renal diseases. For example, increasing water intake is useful to prevent primary and secondary nephrolithiasis. In autosomal dominant polycystic kidney disease, arginine vasopressin (AVP) is involved in the progression of the disease, and water intake could play a therapeutic role by inhibiting the synthesis of AVP, but its efficacy is still controversial. Conversely, the use of aquaretics, which are antagonists of AVP V2 receptors, results in the reduction of the increase rate of total kidney volume with a slower decline of glomerular filtration rate. In chronic kidney disease, AVP contributes to glomerular hyperfiltration, arterial hypertension, and synthesis of renin, resulting in renal sclerosis. Increased water intake could reduce AVP activation determining a potential protective effect on the kidney, but its efficacy has not yet been clearly demonstrated. On the other side, sodium and potassium play an important role in the control of arterial blood pressure and are involved in the development and progression of chronic kidney disease. Reduction of sodium intake and increase of potassium intake determine a decrease of arterial blood pressure with a beneficial effect on the kidney; however, adherence to sodium restriction is very poor. Regarding this, sodium-hydrogen exchanger isoform 3 inhibitors may reduce sodium absorption in the gut. The most recent sodium-hydrogen exchanger isoform 3 inhibitor, known as tenapanor, reduces extracellular fluid volume, left ventricular hypertrophy, albuminuria, and blood pressure in experimental studies and increases fecal loss of sodium in humans.

Strong inhibition of neutrophil-sperm interaction in cattle by selective phosphatidylinositol 3-kinase inhibitors.

The vast majority of sperm are lost from the female reproductive tract in hours following natural mating or artificial insemination in mammals. Multiple complex processes including uterine contractions, mucus barriers, and phagocytosis of sperm by neutrophils have been reported to be involved in the sperm loss, although the contribution of each process is uncertain. If phagocytosis by neutrophils has a significant role in sperm loss, inhibition of neutrophil response to sperm could potentially reduce the dose of sperm required for artificial insemination. Through the development of a quantitative in vitro assay, we have screened 74 candidate compounds for their ability to inhibit the neutrophil-sperm interaction in cattle. Nine inhibitors (GSK2126458, wortmannin, ZSTK474, PIK294, CAL-101, GSK 1059615, GDC-0941, PIK 90 and PI103) active against phosphatidylinositol 3-kinase (PI3-kinase) were most potent, and strongly reduced neutrophil-sperm interaction with an IC50 of 10 nM or less. These inhibitors did not significantly modify sperm motility, and five of the inhibitors did not affect in vitro fertilization. Examination of neutrophil-sperm interaction by time-lapse video microscopy and cell tracking analysis revealed that GSK2126458 may prevent sperm phagocytosis through inhibition of neutrophil movement and/or attachment. Twenty-four other compounds exhibited weaker inhibition (IC50 < 115 µM), and the rest did not inhibit the neutrophil-sperm interaction. Strong PI3-kinase inhibitors identified in this study may be useful to determine the contribution of neutrophil phagocytosis in the clearance of sperm from the female reproductive tract.

[Intoxications in nephrology: clinical cases and local experience in Sciacca Hospital].

Intoxications are a common problem all over the world and cause acid-base balance disturbances, dysionias or acute renal failure; they can develop rapidly leading to severe cellular dysfunction and death. Intoxications and drug overdoses often require the intervention of Nephrologists, for the correction of acidosis, the administration of selective inhibitory enzymes and also hemodialysis treatment. Extracorporeal therapies have been used to remove toxins for over fifty years and have acquired an increasing role, thanks to the use of new treatment modalities in intoxicated patients. In our clinical practice in the Covid period we have found an increase in clinical cases of intoxication with psychiatric drugs, including benzodiazepines, clozapine, lithium, quetiapine and cocaine.

The insecticide 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT) alters the membrane raft location of the TSH receptor stably expressed in Chinese hamster ovary cells.

DDT is a highly lipophilic molecule known to deplete membrane rafts of their phosphoglycolipid and cholesterol contents. However, we have recently shown that DDT can also alter the thyroid homeostasis by inhibiting TSH receptor (TSHr) internalization. The present study was undertaken to verify whether DDT goitrogenic effects are due to the insecticide acting directly on TSHr or via alteration of the membrane rafts hosting the receptor itself. Our results demonstrate that, in CHO-TSHr transfected cells, TSHr is activated in the presence of TSH, while it is inhibited following DDT exposure. DDT can also reduce the endocytic vesicular traffic, alter the extension of multi-branched microvilli along their plasma membranes and induce TSHr shedding in vesicular forms. To verify whether TSHr displacement might depend on DDT altering the raft constitution of CHO-TSHr cell membranes the extent of TSHr and lipid raft co-localization was examined by confocal microscopy. Evidence shows that receptor/raft co-localization increased significantly upon exposure to TSH, while receptors and lipid rafts become dislodged on opposite cell poles in DDT-exposed CHO-TSHr cells. As a control, under similar culturing conditions, diphenylethylene, which is known to be a lipophilic substance that is structurally related to DDT, did not affect the extent of TSHr and lipid raft co-localization in CHO-TSHr cells treated with TSH. These findings corroborate and extend our view that, in CHO cells, the DDT disrupting action on TSHr is primarily due to the insecticide acting on membranes to deplete their raft cholesterol content, and that the resulting inhibition on TSHr internalization is due to receptor dislodgement from altered raft microdomains of the plasma membrane.

Emerging therapeutic strategies for minimal change disease and focal and segmental glomerulosclerosis.

INTRODUCTION: Minimal change disease (MCD) and Focal and segmental glomerulosclerosis (FSGS) are two of the major causes of nephrotic syndrome (NS) in children and adults. According to KDIGO (Kidney Disease: Improving Global Outcomes) guidelines, the treatment of adult primary MCD and FSGS should be based on immunosuppressants and antiproteinuric drugs. Recently, Rituximab, a humanized monoclonal antibody (mAb) has emerged as a potential treatment for steroid or calcineurin inhibitor-dependent patients; it has however demonstrated lower efficacy in those with nephrotic syndrome that is resistant to the above indicated drugs. AREAS COVERED: Analysis of ongoing and already completed clinical trials, retrieved from clinicaltrials.gov, clinicaltrialsregister.eu and PubMed involving new therapies for nephrotic syndrome secondary to MCD and FSGS. EXPERT OPINION: The most promising drugs under investigation for MCD and FSGS are mAbs. We are hopeful that new therapeutic options to treat multi-drug resistant MCD and FSGS will emerge from currently ongoing studies. What appears certain is the difficulty in enrolling patients affected by orphan renal diseases and the selection of valid endpoints in clinical trials, such as kidney failure.

Use of scanning ion conductance microscopy to guide and redirect neuronal growth cones.

Scanning ion conductance microscopy has been applied to neuronal growth cones of the leech either to image or to stimulate them. Growth cone advance was recorded in non-contact mode using a 2% ion current decrease criterion for pipette-membrane distance control. We demonstrate effective growth cone remodelling using a 5% criterion (near-scanning). Recurrent line near-scanning aligned growth cone processes along the scan line. The new membrane protrusions, marked by DiI, started a few minutes after scanning onset and progressively grew in thickness. Using scanning patterns suitable for connecting distinct growth cones, new links were consistently developed. Although the underlying mechanism is still a matter for investigation, a mechanical perturbation produced by the moving probe appeared to induce the process formation. Thanks to its deterministic and interactive features, this novel approach to guiding growth cones is a promising way to develop networks of identified neurons as well as link them with artificial structures.