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Dive into the research topics where Keren Doenyas-Barak is active.

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Featured researches published by Keren Doenyas-Barak.


Seminars in Arthritis and Rheumatism | 2011

Anti-Neutrophil Antibody Associated Vasculitis in Systemic Sclerosis

Uri Arad; Alexandra Balbir-Gurman; Keren Doenyas-Barak; Mirit Amit-Vazina; Dan Caspi; Ori Elkayam

OBJECTIVES To report 3 cases ANCA-associated vasculitis (AAV) that developed in patients suffering from systemic sclerosis (SSc) and to review previously reported cases. METHODS We describe 3 patients diagnosed with SSc who developed severe AAV that presented as crescentic glomerulonephritis (GN) and/or alveolar hemorrhage. A retrospective review of the literature was performed using the PubMed database. RESULTS The first patient presented with rapidly progressive renal failure and then with 2 episodes of massive alveolar hemorrhage. She was partially refractory to treatment with corticosteroids and cyclophosphamide but responded promptly to treatment with rituximab. The second patient suffered from 2 episodes of fulminant alveolar hemorrhage; the first responded to intravenous corticosteroids, but the second was fatal despite aggressive immune suppression with corticosteroids and cyclophosphamide. The third patient presented with a clinical picture compatible with scleroderma renal crisis (SRC) but was later diagnosed with crescentic GN and subsequently died from probable alveolar hemorrhage. Thirty-seven cases of AAV in SSc patients have been described in the English literature. Clinical manifestations include rapidly progressive GN, alveolar hemorrhage, limb ischemia, and vasculitic skin rash. In contrast to SRC that usually develops early in the course of SSc, ANCA-associated GN in SSc patients occurred later, after several years of illness. Hypertension, microangiopathic hemolytic anemia, and thrombocytopenia that are the hallmark of SRC were observed only in a minority of AAV cases. Almost all cases of AAV in SSc were positive for MPO-ANCA. CONCLUSIONS AAV in the setting of SSc is a diagnostic challenge. Differential diagnosis from SRC is crucial as treatment approach for these conditions completely differs. High doses of corticosteroids and immune suppression are advocated in severe AAV. In resistant cases, treatment with rituximab may be considered.


Nephron | 2015

Daily Sodium and Potassium Excretion Can Be Estimated by Scheduled Spot Urine Collections

Keren Doenyas-Barak; Ilia Beberashvili; Adina Bar-Chaim; Zhan Averbukh; Ofir Vogel; Shai Efrati

Aim: The evaluation of sodium and potassium intake is part of the optimal management of hypertension, metabolic syndrome, renal stones, and other conditions. To date, no convenient method for its evaluation exists, as the gold standard method of 24-hour urine collection is cumbersome and often incorrectly performed, and methods that use spot or shorter collections are not accurate enough to replace the gold standard. The aim of this study was to evaluate the correlation and agreement between a new method that uses multiple-scheduled spot urine collection and the gold standard method of 24-hour urine collection. Methods: The urine sodium or potassium to creatinine ratios were determined for four scheduled spot urine samples. The mean ratios of the four spot samples and the ratios of each of the single spot samples were corrected for estimated creatinine excretion and compared to the gold standard. Results: A significant linear correlation was demonstrated between the 24-hour urinary solute excretions and estimated excretion evaluated by any of the scheduled spot urine samples. The correlation of the mean of the four spots was better than for any of the single spots. Bland-Altman plots showed that the differences between these measurements were within the limits of agreement. Conclusion: Four scheduled spot urine samples can be used as a convenient method for estimation of 24-hour sodium or potassium excretion.


American Journal of Nephrology | 2014

Autologous Bone-Marrow Stem Cells Stimulation Reverses Post-Ischemic-Reperfusion Kidney Injury in Rats

Uri Oron; Hana Tuby; Lidya Maltz; Orit Sagi-Assif; Ramzia Abu-Hamed; Tali Yaakobi; Keren Doenyas-Barak; Shai Efrati

Background/Aims: Low-level laser therapy (LLLT) has been found to modulate biological activity. The aim of the present study was to investigate the possible beneficial effects of LLLT application to stem cells in the bone marrow (BM), on the kidneys of rats that had undergone acute ischemia-reperfusion injury (IRI). Methods: Injury to the kidneys was induced by the excision of the left kidney and 60 min of IRI to the right kidney in each rat. Rats were then divided randomly into 2 groups: non-laser-treated and laser-treated. LLLT was applied to the BM 10 min and 24 h post-IRI and rats were sacrificed 4 days post-IRI. Blood was collected before the sacrifice and the kidney processed for histology. Results: Histological evaluation of kidney sections revealed the restored structural integrity of the renal tubules, and a significant reduction of 66% of pathological score in the laser-treated rats as compared to the non-laser-treated ones. C-kit positive cell density in kidneys post-IRI and laser-treatment was (p = 0.05) 2.4-fold higher compared to that of the non-laser treated group. Creatinine, blood urea nitrogen, and cystatin-C levels were significantly 55, 48, and 25% lower respectively in the laser-treated rats as compared to non-treated ones. Conclusion: LLLT application to the BM causes induction of stem cells, which subsequently migrate and home in on the injured kidney. Consequently, a significant reduction in pathological features and improved kidney function post-IRI are evident. The results demonstrate a novel approach in cell-based therapy for acute ischemic injured kidneys. i 2014 S. Karger AG, Basel


The New England Journal of Medicine | 2017

TARGT Gene Therapy Platform for Correction of Anemia in End-Stage Renal Disease

Shany Blum; Nir Shapir; Reem Miari; Benny Lerner; Belly Koren; Keren Doenyas-Barak; Shai Efrati; P. Pergola; Doron Schwartz; Gil Chernin; Yoram Yagil; Serge Guzy; Abraham Nyska; Garry A. Neil

A new protein-delivery platform can provide sustained secretion of recombinant human erythropoietin with the use of small, transduced autologous dermal implants. Study patients with end-stage renal disease were found to have maintenance of stable hemoglobin levels.


Diabetes and Vascular Disease Research | 2014

Serum potassium is an age-dependent risk factor for pre-diabetes and diabetes in the Israeli population

Keren Doenyas-Barak; Ilia Beberashvili; Shlomo Vinker

Objective: We analysed the association between serum potassium, within the normal range, and early signs of diabetes in an Israeli population. Research design and methods: A computerized database of the Clalit Health Services was used for obtaining information regarding patients’ baseline serum potassium levels. The main study outcome was dysglycaemia, defined as fasting glucose > 100 mg/dL, HbA1C > 6.5 gr% (48 mmol/mol) or a new diagnosis of diabetes. A secondary outcome was overt diabetes. Results: Included in the study were 71,597 patients, mean age 40.8 ± 13.4 years. After a mean follow-up period of 5.3 ± 2.2 years, dysglycaemia decreased [odds ratio (OR) = 0.95; 95% confidence interval (CI) = 0.906–0.997; p = 0.038], as did the incidence of overt diabetes (OR = 0.86; 95% CI = 0.793–0.934; p = 0.0001), for every 1 mmol/L elevation in serum potassium in the normal range. But analysis of subpopulation reveals that when elevated serum potassium was associated with low adjusted ORs for predicting dysglycaemia (OR = 0.904 with a 95% CI of 0.849–0.963; p = 0.002), the opposite effect was demonstrated over the age of 41 years (OR = 1.113 with a 95% CI of 1.048–1.104; p < 0.001). Conclusions: This study demonstrates age-related association between serum potassium and the risk of dysglycaemia.


Kidney & Blood Pressure Research | 2017

Response of Renal Podocytes to Excessive Hydrostatic Pressure: a Pathophysiologic Cascade in a Malignant Hypertension Model

Ramzia Abu Hamad; Sylvia Berman; Yafit Hachmo; Moshe Stark; Fadia Hasan; Keren Doenyas-Barak; Shai Efrati

Background/Aims: Renal injuries induced by increased intra-glomerular pressure coincide with podocyte detachment from the glomerular basement membrane (GBM). In previous studies, it was demonstrated that mesangial cells have a crucial role in the pathogenesis of malignant hypertension. However, the exact pathophysiological cascade responsible for podocyte detachment and its relationship with mesangial cells has not been fully elucidated yet and this was the aim of the current study. Methods: Rat renal mesangial or podocytes were exposed to high hydrostatic pressure in an in-vitro model of malignant hypertension. The resulted effects on podocyte detachment, apoptosis and expression of podocin and integrinβ1 in addition to Angiotensin-II and TGF-β1 generation were evaluated. To simulate the paracrine effect podocytes were placed in mesangial cell media pre-exposed to pressure, or in media enriched with Angiotensin-II, TGF-β1 or receptor blockers. Results: High pressure resulted in increased Angiotensin-II levels in mesangial and podocyte cells. Angiotensin-II via the AT1 receptors reduced podocin expression and integrinβ1, culminating in detachment of both viable and apoptotic podocytes. Mesangial cells exposed to pressure had a greater increase in Angiotensin-II than pressure-exposed podocytes. The massively increased concentration of Angiotensin-II by mesangial cells, together with increased TGF-β1 production, resulted in increased apoptosis and detachment of non-viable apoptotic podocytes. Unlike the direct effect of pressure on podocytes, the mesangial mediated effects were not related to changes in adhesion proteins expression. Conclusions: Hypertension induces podocyte detachment by autocrine and paracrine effects. In a direct response to pressure, podocytes increase Angiotensin-II levels. This leads, via AT1 receptors, to structural changes in adhesion proteins, culminating in viable podocyte detachment. Paracrine effects of hypertension, mediated by mesangial cells, lead to higher levels of both Angiotensin-II and TGF-β1, culminating in apoptosis and detachment of non-viable podocytes.


Hemodialysis International | 2018

Immersion-enhanced fluid redistribution can prevent intradialytic hypotension: A prospective, randomized, crossover clinical trial

Keren Doenyas-Barak; Nedal Garra; Ilia Beberashvili; Shai Efrati

Introduction: Intradialytic hypotension (IDH) is an important cause of morbidity and mortality among hemodialysis patients. We used an immersion model to evaluate the role of reduced effective circulating volume, and to examine whether facilitated refilling can prevent IDH.


PLOS ONE | 2016

Effect of Peripheral Electrical Stimulation (PES) on Nocturnal Blood Glucose in Type 2 Diabetes: A Randomized Crossover Pilot Study

Merav Catalogna; Keren Doenyas-Barak; Roi Sagi; Ramzia Abu-Hamad; Uri Nevo; Eshel Ben-Jacob; Shai Efrati

Background Regulation of hepatic glucose production has been a target for antidiabetic drug development, due to its major contribution to glucose homeostasis. Previous pre-clinical study demonstrated that peripheral electrical stimulation (PES) may stimulate glucose utilization and improve hepatic insulin sensitivity. The aim of the present study was to evaluate safety, tolerability, and the glucose-lowering effect of this approach in patients with type 2 diabetes (T2DM). Methods Twelve patients with T2DM were recruited for an open label, interventional, randomized trial. Eleven patients underwent, in a crossover design, an active, and a no-intervention control periods, separated with a two-week washout phase. During the active period, the patients received a daily lower extremity PES treatment (1.33Hz/16Hz burst mode), for 14 days. Study endpoints included changes in glucose levels, number of hypoglycemic episodes, and other potential side effects. Endpoints were analyzed based on continuous glucose meter readings, and laboratory evaluation. Results We found that during the active period, the most significant effect was on nocturnal glucose control (P < 0.0004), as well as on pre-meal mean glucose levels (P < 0.02). The mean daily glucose levels were also decreased although it did not reach clinical significance (P = 0.07). A reduction in serum cortisol (P < 0.01) but not in insulin was also detected after 2 weeks of treatment. No adverse events were recorded. Conclusions These results indicate that repeated PES treatment, even for a very short duration, can improve blood glucose control, possibly by suppressing hepatic glucose production. This effect may be mediated via hypothalamic-pituitary-adrenal axis modulation. Trial registration ClinicalTrials.gov NCT02727790


Molecular Therapy | 2015

29. Clinical Trial Showing EPO-Independence for 7 Months by Prolonged Secretion of Autologous EPO by TARGT™

Shany Blum; Nir Shapir; Reem Miari; Atar Liran; Benny Lerner; Keren Doenyas-Barak; Shai Efrati; Doron Schwartz; Gil Chernin; Garry A. Neil

Recombinant human EPO (rHuEPO) along with iron supplementation corrects anemia in most patients with End StageRenal Disease (ESRD) but is associated with supra-physiological peak serum concentration (Cmax) of EPO and may cause thromboembolic complications.The Transduced Autologous Restorative Gene Therapy system (TARGT™) is an ex-vivo gene therapy that provides autologous, continuous proteins or peptide therapy in the physiological range. The system consists of several 2 × 30 mm pieces of dermal tissue (Micro-Organ, MO), extracted under local anesthetic in which its fibroblasts cells are transduced with a Helper-Dependent Adenoviral Vector (HDAd) containing the EPO gene expression cassette. After culture, and measurement of EPO production, one or more transduced MOs (TARGTs) are re-implanted as required for delivering the target dose. Patients are treated with local steroid injection to stabilize secretion. The system allows dose flexibility and the TARGTs may be removed or added according to the in-vivo secretion levels.We present here initial results from an-ongoing open label ascending dose clinical study of TARGTEPO in patients with anemia due to ESRD. We have completed the enrollment of patients in the first out of 3 cohorts (the low dose) with 6 EPO-dependent patients treated with a total of up to 3 TARGTepo units each, secreting a total of 25 IU/Kg/day of autologous EPO. All patients continued their previous regimen of intravenous supplemental iron.Patients follow-up post implantation is still ongoing with one patient being followed with stable EPO secretion and resulting stable Hb for over 7 months. Results obtained suggest stabilization of serum EPO levels at the physiological range of £20 mIU/ml and the resulting Hb levels between 9-12 g/dL without rHuEPO or transfusion while TARGTs are still functioning. Comparative analysis of serum EPO levels revealed significantly lower Cmax with TARGTepo compared to rHuEPO. Also, comparison of extrapolated Area Under the Curve (AUC) of rhEPO vs. actual TARGTepo AUC, revealed that TARGTepo maintained Hb within the desired range in patients with an order of magnitude smaller exposure to EPO compared to rHuEPO. This observation may have significant clinical benefits. No treatment related serious adverse events have been reported. TARGTEPO is a promising novel therapy for anemia and potentially for other protein deficient diseases.


Critical Care | 2015

Lactic acidosis and severe septic shock in metformin users: a cohort study

Keren Doenyas-Barak; Ilia Beberashvili; Ronit Marcus; Shai Efrati

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Doron Schwartz

Tel Aviv Sourasky Medical Center

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