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result(s) for
"Landau, Daniel"
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Experimental modulation of Interleukin 1 shows its key role in chronic kidney disease progression and anemia
2021
Inflammation in chronic kidney disease (CKD) is mostly due to activation of the innate immune system, in which Interleukin-1 (IL-1) is a key player. Anemia of CKD may also be due to erythropoietin (EPO) resistance, clinically associated with inflammation. IL-1 receptor antagonist knockout (RaKO) mice show arthritis and excessive inflammation. Inhibition of IL-1 was shown to be beneficial in many inflammatory conditions, but its role in CKD and anemia is unknown. Here, we report that enhanced inflammation in RaKO mice with CKD provoked both higher degrees of renal insufficiency and anemia in comparison to wild-type CKD, in association with a downregulation of renal hypoxia inducible factor-2 (HIF2) as well as decreased bone marrow EPO-receptor (EPOR) and transferrin receptor (TFR). In contrast, administration of P2D7KK, an anti-IL1b monoclonal antibody, to CKD mice results in a lower grade of systemic inflammation, better renal function and blunted anemia. The latter was associated with upregulation of renal HIF-2α, bone marrow EPO-R and TFR. Altogether, this supports the key role of inflammation, and IL-1 particularly, in CKD progression and anemia. Novel treatments to reduce inflammation through this and other pathways, may improve renal function, attenuate the anemic state or increase the response to exogenous EPO.
Journal Article
The hypoxia inducible factor/erythropoietin (EPO)/EPO receptor pathway is disturbed in a rat model of chronic kidney disease related anemia
by
Bandach, Inbar
,
Segev, Yael
,
London, Lital
in
Anemia
,
Anemia - etiology
,
Anemia - physiopathology
2018
Anemia is a known driver for hypoxia inducible factor (HIF) which leads to increased renal erythropoietin (EPO) synthesis. Bone marrow (BM) EPO receptor (EPOR) signals are transduced through a JAK2-STAT5 pathway. The origins of anemia of chronic kidney disease (CKD) are multifactorial, including impairment of both renal EPO synthesis as well as intestinal iron absorption. We investigated the HIF- EPO- EPOR axis in kidney, BM and proximal tibia in anemic juvenile CKD rats.
CKD was induced by 5/6 nephrectomy in young (20 days old) male Sprague-Dawley rats while C group was sham operated. Rats were sacrificed 4 weeks after CKD induction and 5 minutes after a single bolus of IV recombinant human EPO. An additional control anemic (C-A) group was daily bled for 7 days.
Hemoglobin levels were similarly reduced in CKD and C-A (11.4 ± 0.3 and 10.8±0.2 Vs 13.5±0.3 g/dL in C, p<0.0001). Liver hepcidin mRNA was decreased in CA but increased in CKD. Serum iron was unchanged while transferrin levels were mildly decreased in CKD. Kidney HIF2α protein was elevated in C-A but unchanged in CKD. Kidney EPO protein and mRNA levels were unchanged between groups. However, BM EPO protein (which reflects circulating EPO) was increased in C-A but remained unchanged in CKD. BM and proximal tibia EPOR were unchanged in C-A but decreased in CKD. Proximal tibial phospho-STAT5 increased after the EPO bolus in C but not in CKD.
Compared to blood loss, anemia in young CKD rats is associated with inappropriate responses in the HIF-EPO-EPO-R axis: kidney HIF2α and renal EPO are not increased, BM and bone EPOR levels, as well as bone pSTAT5 response to EPO are reduced. Thus, anemia of CKD may be treated with additional therapeutic avenues beyond iron and EPO supplementation.
Journal Article
Coherent chaos in a recurrent neural network with structured connectivity
by
Landau, Itamar Daniel
,
Sompolinsky, Haim
in
Biology and Life Sciences
,
Broken symmetry
,
Coherence
2018
We present a simple model for coherent, spatially correlated chaos in a recurrent neural network. Networks of randomly connected neurons exhibit chaotic fluctuations and have been studied as a model for capturing the temporal variability of cortical activity. The dynamics generated by such networks, however, are spatially uncorrelated and do not generate coherent fluctuations, which are commonly observed across spatial scales of the neocortex. In our model we introduce a structured component of connectivity, in addition to random connections, which effectively embeds a feedforward structure via unidirectional coupling between a pair of orthogonal modes. Local fluctuations driven by the random connectivity are summed by an output mode and drive coherent activity along an input mode. The orthogonality between input and output mode preserves chaotic fluctuations by preventing feedback loops. In the regime of weak structured connectivity we apply a perturbative approach to solve the dynamic mean-field equations, showing that in this regime coherent fluctuations are driven passively by the chaos of local residual fluctuations. When we introduce a row balance constraint on the random connectivity, stronger structured connectivity puts the network in a distinct dynamical regime of self-tuned coherent chaos. In this regime the coherent component of the dynamics self-adjusts intermittently to yield periods of slow, highly coherent chaos. The dynamics display longer time-scales and switching-like activity. We show how in this regime the dynamics depend qualitatively on the particular realization of the connectivity matrix: a complex leading eigenvalue can yield coherent oscillatory chaos while a real leading eigenvalue can yield chaos with broken symmetry. The level of coherence grows with increasing strength of structured connectivity until the dynamics are almost entirely constrained to a single spatial mode. We examine the effects of network-size scaling and show that these results are not finite-size effects. Finally, we show that in the regime of weak structured connectivity, coherent chaos emerges also for a generalized structured connectivity with multiple input-output modes.
Journal Article
Young generations’ hopelessness perpetuates long-term conflicts
2023
Transforming long-term conflicts into peaceful intergroup relations is one of the most difficult challenges for humanity. Such meaningful social changes are often driven by young people. But do young people living in contexts of long-term conflicts believe that change is even possible? In a series of six studies (
N
total
= 119,671) over two decades and across two unrelated intractable conflicts in Israel/Palestine and Cyprus, we found that younger (compared to older) generations from both respective rival groups have less hope for peace, and consequently less conciliatory attitudes. We also show that this gradual improvement of peace-promoting emotions and attitudes with increasing age can be experimentally accelerated in young people through a virtual reality-based aging simulation. These findings provide a new perspective on the fundamental question of why long-term conflicts are so difficult to resolve and highlight the importance of instilling hope in young generations to advance peace processes.
Journal Article
Growth Hormone and IGF1 Actions in Kidney Development and Function
by
Gurevich, Evgenia
,
Segev, Yael
,
Landau, Daniel
in
Animal models
,
Animals
,
Animals, Genetically Modified
2021
Growth hormone (GH) exerts multiple effects on different organs including the kidneys, either directly or via its main mediator, insulin-like-growth factor-1 (IGF-1). The GH/IGF1 system plays a key role in normal kidney development, glomerular hemodynamic regulation, as well as tubular water, sodium, phosphate, and calcium handling. Transgenic animal models demonstrated that GH excess (and not IGF1) may lead to hyperfiltration, albuminuria, and glomerulosclerosis. GH and IGF-1 play a significant role in the early development of diabetic nephropathy, as well as in compensatory kidney hypertrophy after unilateral nephrectomy. Chronic kidney disease (CKD) and its complications in children are associated with alterations in the GH/IGF1 axis, including growth retardation, related to a GH-resistant state, attributed to impaired kidney postreceptor GH-signaling and chronic inflammation. This may explain the safety of prolonged rhGH-treatment of short stature in CKD.
Journal Article
Interdisciplinary approach in post-cardiac arrest anoxic brain injury with unconfirmed brain death
2025
Background
Severe anoxic brain injury after cardiac arrest can produce a clinical picture suggestive of brain death (BD). However, when ancillary testing, such as radionuclide cerebral perfusion scans (RCPS), shows preserved cerebral perfusion, the diagnosis of brain death cannot be confirmed, complicating end-of-life decision-making.
Case summary
We present a case of a post-cardiac arrest patient with profound neurological injury and absent brainstem reflexes. Although the clinical findings resembled brain death, two RCPS showed preserved cerebral perfusion, ruling out a formal brain death diagnosis. As a result, withdrawal of life-sustaining therapies was not permitted under existing protocols, despite a poor prognosis.
Key points
Question
How should clinicians navigate end-of-life care in cases of anoxic brain injury with unconfirmed brain death?
Findings
This case underscores that when severe anoxic brain injury with unconfirmed brain death occurs, the focus must shift beyond diagnostic algorithms toward a broader, human-centered approach.
Meaning
Interdisciplinary collaboration—including the involvement of the palliative care team—ensures that in cases of unconfirmed brain death, care remains guided by integrity, empathy, and the best interests of the patient and family. An interdisciplinary ICU team—including intensivists, neurologists, and the palliative care team—worked together to engage the patient’s family. This collaboration enabled clear communication, support through complex decisions, and a focus on compassionate and goal-concordant care.
Conclusion
In post-cardiac arrest patients with anoxic brain injury with unconfirmed brain death, interdisciplinary teamwork is vital. Palliative care team involvement ensures ethically sound, patient-centered care in this complex situation.
Journal Article
The enemy’s gaze: Immersive virtual environments enhance peace promoting attitudes and emotions in violent intergroup conflicts
2019
Perspective-taking is essential for improving intergroup relations. However, it is difficult to implement, especially in violent conflicts. Given that immersive virtual reality (VR) can simulate various points of view (POV), we examined whether it can lead to beneficial outcomes by promoting outgroup perspective-taking, even in armed conflicts. In two studies, Jewish-Israelis watched a 360° VR scene depicting an Israeli-Palestinian confrontation from different POVs-outgroup's, ingroup's while imagining outgroup perspective or ingroup's without imagined perspective-taking. Participants immersed in the outgroup's POV, but not those who imagined the outgroup's perspective, perceived the Palestinians more positively than those immersed in the ingroup's POV. Moreover, participants in the outgroup's POV perceived the Palestinian population in general more favorably and judged a real-life ingroup transgression more strictly than those in the ingroup's POV, even five months after VR intervention. Results suggest that VR can promote conflict resolution by enabling effective perspective-taking.
Journal Article
Hyperuricemia and gout caused by missense mutation in d-lactate dehydrogenase
by
Zalk, Ran
,
Yogev, Yuval
,
Halperin, Daniel
in
Amino acids
,
Concise Communication
,
Development and progression
2019
Gout is caused by deposition of monosodium urate crystals in joints when plasma uric acid levels are chronically elevated beyond the saturation threshold, mostly due to renal underexcretion of uric acid. Although molecular pathways of this underexcretion have been elucidated, its etiology remains mostly unknown. We demonstrate that gout can be caused by a mutation in LDHD within the putative catalytic site of the encoded d-lactate dehydrogenase, resulting in augmented blood levels of d-lactate, a stereoisomer of l-lactate, which is normally present in human blood in miniscule amounts. Consequent excessive renal secretion of d-lactate in exchange for uric acid reabsorption culminated in hyperuricemia and gout. We showed that LDHD expression is enriched in tissues with a high metabolic rate and abundant mitochondria and that d-lactate dehydrogenase resides in the mitochondria of cells overexpressing the human LDHD gene. Notably, the p.R370W mutation had no effect on protein localization. In line with the human phenotype, injection of d-lactate into naive mice resulted in hyperuricemia. Thus, hyperuricemia and gout can result from the accumulation of metabolites whose renal excretion is coupled to uric acid reabsorption.
Journal Article
A Nuphar lutea plant active ingredient, 6,6′-dihydroxythiobinupharidine, ameliorates kidney damage and inflammation in a mouse model of chronic kidney disease
2024
Chronic Kidney Disease (CKD) associated complications are associated with increased inflammation through the innate immune response, which can be modulated with anti-inflammatory agents. An active ingredient derived from the
Nuphar lutea
aquatic plant, 6,6′-dihydroxythiobinupharidine (DTBN) has anti-inflammatory properties, mainly through the inhibition of NF-κB. We tested the effects of DTBN on mice with CKD. After preliminary safety and dosing experiments, we exposed 8 weeks old male C57BL/6J mice to adenine diet to induce CKD. Control and CKD animals were treated with IP injections of DTBN (25 μg QOD) or saline and sacrificed after 8 weeks. Serum urea and creatinine were significantly decreased in CKD-DTBN Vs CKD mice. Kidney histology showed a decrease in F4/80 positive macrophage infiltration, damaged renal area, as well as decreased kidney TGF-β in CKD-DTBN Vs CKD mice. Kidney inflammation indices (IL-1β, IL-6 and P-STAT3) were significantly decreased in CKD-DTBN as compared to CKD mice. DTBN treatment showed no apparent damage to tissues in control mice, besides a decrease in weight gain and mild hypoalbuminemia without proteinuria. Thus, DTBN significantly improved renal failure and inflammation indices in CKD mice. Therefore, this and similar substances may be considered as an additional treatment in CKD patients.
Journal Article
An audit analysis of a guideline for the investigation and initial therapy of diarrhea negative (atypical) hemolytic uremic syndrome
by
Johnson, Sally
,
Landau, Daniel
,
Siomou, Ekaterini
in
Adolescent
,
Apheresis
,
Atypical Hemolytic Uremic Syndrome - therapy
2014
Background
In 2009, the European Paediatric Study Group for Haemolytic Uraemic Syndrome (HUS) published a clinical practice guideline for the investigation and initial therapy of diarrhea-negative HUS (now more widely referred to as atypical HUS, aHUS). The therapeutic component of the guideline (comprising early, high-volume plasmapheresis) was derived from anecdotal evidence and expert consensus, and the authors committed to auditing outcome.
Methods
Questionnaires were distributed to pediatric nephrologists across Europe, North America, and the Middle East, who were asked to complete one questionnaire per patient episode of aHUS between July 1, 2009 and December 31, 2010. Comprehensive, anonymous demographic and clinical data were collected.
Results
Seventy-one children were reported with an episode of aHUS during the audit period. Six cases occurred on a background of influenza A H1N1 infection. Of 71 patients, 59 (83 %) received plasma therapy within the first 33 days, of whom ten received plasma infusion only. Complications of central venous catheters occurred in 16 out of 51 patients with a catheter in-situ (31 %). Median time to enter hematological remission was 11.5 days, and eight of 71 (11 %) patients did not enter hematological remission by day 33. Twelve patients (17 %) remained dialysis dependent at day 33.
Conclusions
This audit provides a snapshot of the early outcome of a group of children with aHUS in the months prior to more widespread use of eculizumab.
Journal Article