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Yaacov Ori

Publications and source records attributed to Yaacov Ori.

At least 19 recordsLinked to original sources
PubMed2006

Effect of hemodialysis on the thickness of vocal folds: a possible explanation for postdialysis hoarseness.

BACKGROUND: Determining the dry weight of chronically hemodialysed patients is a common problem. Patients on intermittent hemodialysis often experience transient hoarseness at the end of dialysis. The vocal folds may be affected by the hydration state. AIM: To test the hypothesis that postdialysis hoarseness may be related to changes in the thickness of the vocal folds. METHODS: Twenty-five stable chronic hemodialysis patients underwent endoscopic nasopharyngeal laryngoscopy before and after dialysis. Pictures of the vocal folds were taken and the folds were measured using computer software. Eighteen vocal folds from 16 patients were technically adequate for analysis. The change in the width/length ratio of the vocal folds (W/L) was used as a measurement of the folds' thickness. RESULTS: W/L decreased from 0.175 +/- 0.011 before dialysis to 0.152 +/- 0.009 after dialysis (p < 0.01, mean reduction 10.9 +/- 3.8%). Patients' weight decreased by 4.7 +/- 0.3% (p < 0.0001), systolic blood pressure decreased by 15.0 +/- 3.1% (p < 0.001), diastolic blood pressure decreased by 13.0 +/- 3.6% (p < 0.01), and mean blood pressure decreased by 14.1 +/- 3.1% (p < 0.001). Sixty percent of the patients had postdialysis hoarseness, and in 72% of the patients a decrease in the vocal folds' thickness was observed. CONCLUSIONS: Chronic hemodialysis patients may experience transient postdialysis hoarseness, and a decrease in the vocal folds' thickness. The latter may result from dehydration.

Adult↗
PubMed2006

[Nephrotic syndrome as a first manifestation of familial Mediterranean fever].

AA amyloidosis may be a complication of Familial Mediterranean Fever (FMF). This is a case history of a female patient who did not have the classic symptoms of FMF, which usually precede the renal manifestation. The patient was admitted with edema of both legs, and the nephrotic syndrome was discovered, leading to the diagnosis of AA amyloidosis on kidney biopsy. Genetic testing uncovered the homozygous M694V type mutation, the most common mutation of FMF, which renders the patients prone to amyloidosis. This case represents the phenotype II of FMF, which presents with amyloidosis without prior classic attacks of FMF. Since effective prevention of the development of amyloidosis is available, genetic testing should be considered in order to identify mutations which carry high risk for the development of amyloidosis. This is also relevant in asymptomatic individuals with family history of FMF.

Biopsy↗
PubMed2005

Spontaneous DNA repair in human mononuclear cells is calcium-dependent.

Spontaneous DNA repair in peripheral blood mononuclear cells (PBMC) has been recently described. The aim of this study was to evaluate whether spontaneous DNA repair is Ca(2+)-dependent, as in vitro-stimulated DNA repair. Spontaneous DNA repair in PBMC was measured in a 1mM Ca2+ medium. The effect of extracellular Ca2+ chelation by EGTA, intracellular Ca2+ chelation by bapta-AM, and Ca2+ loading by the ionophore A23187 was examined. The signal transduction pathway was evaluated by inhibiting protein tyrosine kinase with genistein, calmodulin with W7, and calcineurin with cyclosporin A and tacrolimus. Extracellular Ca2+ chelation had no effect on spontaneous DNA repair, while both intracellular chelation and calcium overloading inhibited the DNA repair. Inhibition of protein tyrosine kinase, calmodulin or calcineurin reduced DNA repair. In conclusion, spontaneous DNA repair is mainly Ca(2+)-dependent at a narrow range of intracellular Ca2+ concentrations. The signal transduction cascade includes protein tyrosine kinase, calmodulin, and calcineurin.

Calcimycin↗
PubMed2005

Non-occlusive mesenteric ischemia in chronically dialyzed patients: a disease with multiple risk factors.

BACKGROUND: Non-occlusive mesenteric ischemia (NOMI) can be a fatal complication in dialysis patients. Intradialytic hypotension is usually the precipitating factor. The occurrence of 16 cases in 5 years (1998-2002), compared with only 4 in previous years, led us to investigate other risk factors contributing to NOMI. A control group of stable hemodialysis patients was used for comparison. RESULTS: 20 patients were studied: 17 diagnosed surgically, and 3 clinically. The mean age was 70.8 +/- 1.8 years, and the male:female ratio 7:13. Nineteen patients were on hemodialysis. Clinically overt atherosclerosis was present in 17 patients. Preceding dialysis-associated hypotension was identified in all patients studied and access thrombosis in 6 patients. In all patients, abdominal pain was the presenting symptom. Initial abdominal examination was unimpressive in 16 patients. The hemoconcentration, leukocytosis and metabolic acidosis were the most prominent laboratory findings. 5/11 abdominal sonograms showed intestinal pathology. 2/3 angiographies were diagnostic. Three patients responded to early fluid challenge and did not require surgery. Pathology was related to the area of the superior mesenteric artery in all 15 patients operated. Twelve (60%) patients died from the event. The 1-year mortality rate was 17/20 patients (85%). Possible contributing factors, other than dialysis-associated hypotension, included: high-dose recombinant human erythropoietin (rhEPO) therapy (179 +/- 35 vs. 116 +/- 10 U/kg/week in the control group, p < 0.05); metastatic calcifications (abdominal aorta 14/14, aortic valve 11/18; medial calcification of mesenteric arteries in 2/11 pathology specimens); digoxin, and hypoalbuminemia. CONCLUSIONS: The increased incidence of NOMI in dialysis patients may be related to overly aggressive rhEPO therapy and the unsuspected presence of mesenteric arterial medial calcifications. Identification of patients at risk, prevention of intradialytic hypotension and a controlled increase in dry weight may help to reduce the incidence of NOMI in chronically dialyzed patients.

Aged↗
PubMed2004

Spontaneous DNA repair in human peripheral blood mononuclear cells.

DNA molecules are constantly damaged during mitosis and by oxygen-free radicals produced by either cellular metabolism or by external factors. Populations at risk include patients with cancer-prone disease, patients under enhanced oxidative stress, and those treated with immunosuppressive/cytotoxic therapy. The DNA repair process is crucial in maintaining the genomal DNA integrity. The aim of this study was to evaluate spontaneous DNA repair capacity of peripheral blood mononuclear cells (PBMC) from normal blood donors. PBMC DNA repair ability represents DNA repair by other tissues as well. It is shown in the present study that in vitro incorporation of [3H]thymidine in non-stimulated PBMC expresses the ability of the cells to repair DNA damage. This method was validated by double-stranded DNA measurements. Both catalase and Fe2+ increased DNA repair, the former by preventing re-breakage of newly repaired DNA and the latter by introducing additional DNA damage, which enhanced DNA repair. Better understanding of DNA repair processes will enable to minimize DNA damage induced by oxidative stress.

Cytarabine↗
PubMed2004

Ischemic optic neuropathy in dialyzed patients: a previously unrecognized manifestation of calcific uremic arteriolopathy.

Two patients with end-stage renal disease and on long-term hemodialysis presented with hypotension and an acute unilateral loss of vision. A diagnosis of anterior ischemic optic neuropathy (AION) was made quickly, but despite high-dose steroid therapy, significant vision was not recovered. Temporal artery biopsy results showed extensive medial calcification. The possibility that hypotension, when coupled with calcific uremic arteriolopathy in arteries supplying the optic nerve head, will lead to AION in dialyzed patients is discussed. A short review of AION in the dialysis population is given.

Aged↗
PubMed2004

Improved immunogenicity of a novel third-generation recombinant hepatitis B vaccine in patients with end-stage renal disease.

Hepatitis B (HBV) infection remains a significant epidemiological problem in the end-stage renal disease (ESRD) population. Vaccination programs using second-generation vaccines lead to effective seroprotection in only 50-60% of these patients. The purpose of this case series was to describe our experience with a novel third-generation vaccine, Bio-Hep-B, in ESRD patients who had not developed protective anti-HBs titers following a second-generation HBV vaccination protocol. Twenty-nine ESRD patients who had not responded in the past to a standard second-generation HBV vaccination protocol were included in this series. Each patient received 10 microg of Bio-Hep-B) intramuscularly at 0, 1 and 6 months. A month after completion of the vaccination protocol, anti-HBs antibody levels were measured. Following immunization, 25 of 29 patients (86%) developed seroprotective anti-HBs levels > or =10 mIU/ml. There was a significant difference in the titers of anti-HBs antibodies prior to and following vaccination (p < 0.0001). Statistical analysis of the variables age, gender, diagnosis, dialysis mode, weight, hemoglobin, albumin, and KT/V failed to detect predictors of antibody response. A retrospective analysis of the results of a second-generation vaccination program for the years 1999-2001 in our department showed that 19 of 36 (56.4%) ESRD patients developed seroprotection. In conclusion, the results of this study show that the third-generation HBV vaccine Bio-Hep-B is highly immunogenic in the population of ESRD patients who did not respond in the past to a second-generation vaccine. This enhanced seroprotection offers hope that the new vaccine will reduce the rate of non-responders and help to eliminate HBV infection from dialysis centers.

Adult↗
PubMed2003

The effects of weight loss on renal function in patients with severe obesity.

Severe obesity is associated with increased renal plasma flow (RPF) and glomerular filtration rate (GFR). The aim of the present study was to examine whether weight loss may reverse glomerular dysfunction in obese subjects without overt renal disease. Renal glomerular function was studied in eight subjects with severe obesity (body mass index [BMI] 48.0 +/- 2.4) before and after weight loss. Nine healthy subjects served as controls. GFR and RPF were determined by measuring inulin and PAH clearance. In the obese group, GFR (145 +/- 14 ml/min) and RPF (803 +/- 39 ml/min) exceeded the control value by 61% (90 +/- 5 ml/min, P = 0.001) and 32% (610 +/- 41 ml/min, P < 0.005), respectively. Consequently, filtration fraction was increased. Mean arterial pressure, although normal, was higher than in the control group (101 +/- 4 versus 86 +/- 2 mmHg, P < 0.01). After weight loss, BMI decreased by 32 +/- 4%, to 32.1 +/- 1.5 (P = 0.001). GFR and RPF decreased to 110 +/- 7 ml/min (P = 0.01) and 698 +/- 42 ml/min (P < 0.02), respectively. Albumin excretion rate decreased from 16 microg/min (range, 4 to 152 microg/min) to 5 microg/min (range, 3 to 37 microg/min) (P < 0.01). Fractional clearance of albumin decreased from 3.2 x 10(-6) (range, 1.1 to 23 x 10(-6)) to 1.2 x 10(-6) (range, 0.5 to 6.8 x 10(-6)) (P < 0.02). This study shows that obesity-related glomerular hyperfiltration ameliorates after weight loss. The improvement in hyperfiltration may prevent the development of overt obesity-related glomerulopathy.

Adult↗
PubMed2003

Lower extremity amputations in chronically dialysed patients: a 10 year study.

BACKGROUND: Lower limb critical ischemia is a major problem in dialysed patients. OBJECTIVE: To evaluate the results of revascularization procedures, amputations and prosthetic rehabilitation in dialysed amputees. METHODS: In this retrospective study we examined the charts of selected dialysis patients. Forty-eight patients had undergone major amputation (4.5% of the dialysis population), and 24 patients entered the rehabilitation program. Widespread arterial calcification was common and led to falsely elevated ankle-brachial pressure indices in 9 of 14 limbs. Eight patients underwent revascularization. Subsequent major amputation was carried out 4 +/- 4.5 months after the revascularization (above knee in 5 patients and below knee in 3). Of the 16 patients who underwent primary amputation, only 2 were above-knee amputees. Seven patients with toe or metatarsal amputation went on to a major amputation 1.8 +/- 1.2 months after the distal amputation. RESULTS: No differences were found between diabetic and non-diabetic patients regarding the number of revascularization operations performed, the level of major amputation, or overall survival. Prosthetic rehabilitation was considered successful in 12 patients, partially successful in 8, and failed in 4 patients. Patient survival time was shortest in those patients with failed rehabilitation. A younger age confirmed favorable rehabilitation results, while long-standing diabetics and bilateral amputees were poor rehabilitation candidates. Patients who underwent primary amputation had more successful rehabilitation. A comparison between 24 dialysed amputees and 138 non-uremic amputees revealed similar rehabilitation results, although hospitalization time was longer in the dialysed patients. CONCLUSIONS: Early definitive therapy is essential when dealing with critical ischemia. After diagnostic angiography, proximal revascularization should be performed where feasible. Primary amputation is indicated in patients with extensive foot infection or gangrene. Prosthetic rehabilitation is warranted in most dialysed amputees.

Adult↗
PubMed2002

The contribution of an arteriovenous access for hemodialysis to left ventricular hypertrophy.

BACKGROUND: The long-term isolated contribution of hemodialysis arteriovenous access (AVA) to cardiac hemodynamics has not been previously investigated in a prospective manner. METHODS: Twelve predialysis patients were studied before and 1 and 3 months after creation of a primary AVA. Evaluation included relevant clinical parameters, echocardiographic studies, and hemodynamic hormones. RESULTS: After creation of an AVA, there was no change in patient weight, blood pressure or hemoglobin level. Cardiac index increased and systemic vascular resistance decreased. Left ventricular mass (LVM) corrected to height increased from 63.8 +/- 5.5 to 68.9 +/- 4.9 g/m(2.7) at 1 month (P = 0.05) and 72.5 +/- 8.9 g/m(2.7) at 3 months (P < 0.05). This increase in LVM was accounted for mostly by an increase in interventricular septal thickness, whereas left ventricular end-diastolic diameter and posterior wall thickness did not change. The incidence of left ventricular hypertrophy (LVH) increased from 67% at baseline to 83% and 90% at 1 and 3 months, respectively. Left atrial area increased from 17.6 +/- 1.0 cm(2) at baseline to 19.7 +/- 1.3 cm(2) at 1 month (P < 0.01) and 20.2 +/- 1.2 cm(2) at 3 months (P < 0.05). Early diastolic transmitral flow increased from 68.0 +/- 4.2 cm/s at baseline to 85.6 +/- 7.3 and 89.2 +/- 6.5 cm/s at 1 and 3 months, respectively (P < 0.01). Inferior vena cava diameter increased at 1 month and did not change at 3 months. Plasma atrial natriuretic polypeptide levels increased from 268 +/- 35 pg/mL (87 +/- 11 pmol/L) at baseline to 461 +/- 63 pg/mL (150 +/- 20 pmol/L) at 1 month (P < 0.01) and 610 +/- 96 pg/mL (198 +/- 31 pmol/L) at 3 months (P < 0.01). Plasma renin activity and serum aldosterone levels decreased. Plasma angiotensin II, angiotensin-converting enzyme, and endothelin levels did not change. CONCLUSION: Creation of a hemodialysis AVA is independently associated with further progression of already existing LVH.

Adult↗
PubMed2002

DNA repair in mononuclear cells: role of serine/threonine phosphatases.

Treatment with cyclosporin A (CsA) in kidney-transplant recipients is associated with reduced DNA repair and enhanced cancer incidence. CsA is an inhibitor of the serine/threonine phosphatase calcineurin, also termed PP2B, which is a Ca(2+)/calmodulin-dependent phosphatase. In this study we sought to elucidate the role of calcineurin in DNA repair using CsA and tacrolimus; examine whether UV-induced DNA repair is associated with dephosphorylation; and investigate whether phosphatases other than calcineurin are active in DNA repair, in light of the fact that calcineurin inhibition only partially suppressed DNA repair. Peripheral blood mononuclear cells from healthy donors were used. In vitro, we assayed UV-induced DNA repair by measuring the incorporation of tritiated thymidine in UV-irradiated cells. We gauged phosphatase activity indirectly by measuring free inorganic phosphate (Pi) excreted into the medium. The phosphatase assay was performed under the same conditions and in parallel to the DNA-repair assay. Tacrolimus, like CsA, inhibited DNA repair in a dose-dependent fashion. DNA repair was associated with production of Pi, which correlated with the number of cells performing DNA repair. Phosphatase activity increased after UV irradiation. DNA repair correlated directly with phosphatase activity, whereas CsA reduced both DNA repair and Pi production. Inhibition of calmodulin by trifluoperazine and W7 [N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide] reduced DNA repair in part. We investigated the role of the Ca(2+)-independent phosphatases PP1 and PP2A using specific inhibitors. Calyculin A, which inhibits both phosphatases, reduced DNA repair. Endothall, a PP2A inhibitor, had no effect on DNA repair. Okadaic acid, which is mostly a PP2A inhibitor but also a weak inhibitor of PP1, reduced DNA repair only slightly. We suggest that DNA repair is mediated by way of Ca(2+)-dependent and Ca(2+)-independent pathways, with calcineurin and PP1 being the respective phosphatases involved in each pathway.

Calcineurin↗
PubMed2002

Effect of increased dialysate volume on peritoneal surface area among peritoneal dialysis patients.

Large dialysate volumes are often required to increase solute clearance for peritoneal dialysis patients. The resulting increase in solute clearance might be attributable to an increased plasma-to-dialysate concentration gradient and/or to an increased effective peritoneal surface area. One of the factors affecting the latter is the peritoneal surface area in contact with dialysate (PSA-CD). The aim of this study was to estimate the change in PSA-CD after a 50% increase in the instilled dialysate volume for patients undergoing peritoneal dialysis. PSA-CD was estimated by using a method applying stereologic techniques to computed tomographic (CT) scans of the peritoneal space. The peritoneal cavity of 10 peritoneal dialysis patients was filled with a solution containing dialysate, half-isotonic saline solution, and contrast medium. Peritoneal function tests and CT scanning of the abdomen were performed twice for each patient (with an interval of 1 wk), after instillation of a 2- or 3-L solution. Scanning of thin helical CT sections was performed, and 36 random sections of the abdomen were obtained after reconstruction. A grid was superimposed on the sections. The surface area was estimated by using stereologic methods. After instillation of the 2-L solution, the volume of the peritoneal solution at the time of CT scanning was 2.32 +/- 0.05 L. The PSA-CD was 0.57 +/- 0.03 m(2), ranging from 0.41 to 0.76 m(2). The use of the 3-L solution increased the peritoneal volume by 46 +/- 2%. PSA-CD increased by 18 +/- 2.3% to 0.67 +/- 0.04 m(2) (range, 0.49 to 0.84 m(2); P < 0.01). Creatinine mass transfer increased from 112 +/- 10 mg to 142 +/- 11 mg (P < 0.0001). The slope of the change of the plasma-to-dialysate creatinine concentration gradient with time decreased from -2.26 +/- 0.23 x 10(-2) to -1.97 +/- 0.16 x 10(-2) (P = 0.01). K(BD-0) (permeability-surface area product or mass area transfer coefficient at time 0 of the dwell) increased from 10.6 +/- 0.7 to 13.6 +/- 1.2 ml/min (P < 0.02). These data demonstrate that increasing the instilled dialysate volume by 50% for peritoneal dialysis patients results in significant increases in the PSA-CD and K(BD).

Adult↗