Antibiotic availability for outpatient treatment of acute peritonitis in chronic peritoneal dialysis patients: A case series.

BACKGROUND: Peritoneal dialysis (PD) is a commonly used form of renal replacement therapy for patients that have reached end-stage renal disease. Acute bacterial peritonitis (ABP) in chronic PD patients results in pain, increased costs, injury to the peritoneal membrane, and PD modality failure. Optimal antibiotic treatment of acute bacterial peritonitis (ABP) in chronic PD patients should be intraperitoneal, outpatient-based, appropriate, prompt, and uninterrupted. We investigated the frequency of and predisposition to suboptimal antibiotic courses for ABP in our chronic PD patients. METHODS: Twenty-four charts of patients with ABP were reviewed, to test the null hypothesis that all ABP patients received antibiotics optimally. RESULTS: After 12 patient exclusions (hospitalization), 9 suboptimal antibiotic events were detected in 6 of the remaining 12 patients, disproving the null hypothesis (p < 0.02). Most suboptimal antibiotics courses (7 of 9) resulted from delays and/or gaps in therapy or antibiotics prescribed outside of community standard. Suboptimal antibiotic events occurred on nights and weekends rather than during the workweek (p < 0.02) and in the emergency room rather than the PD clinic (p < 0.02). CONCLUSIONS: Suboptimal ABP antibiotic therapy occurs commonly and is influenced by time and location of presentation and lack of knowledge by patients and physicians. Prevention of suboptimal antibiotic courses in the treatment of ABP in chronic PD patients includes education of patients and providers and allowing emergency rooms and PD clinics to dispense antibiotics for home use.

Hyperkalemia in chronic peritoneal dialysis patients.

Background. Chronic peritoneal dialysis (PD) patients often develop hypokalemia but less commonly hyperkalemia.Methods. We explored incidence and mechanisms of hyperkalemia in 779 serum samples from 33 patients on PD for 1 - 59 months. Normal serum potassium concentration was defined as 3.5 - 5.1 meq/l.Results. Mean monthly serum potassium concentrations were normal (except for 1 month), but we observed hypokalemia (<3.5 meq/l) in 5% and hyperkalemia (>5.1 meq/l) in 14% of 779 serum samples. Incidence of hyperkalemia did not change over time on PD: Year 1 (15%), Year 2 (11%), Year 3 (19%), Years 4-5 (22%). Hyperkalemia was mostly modest but occasionally extreme [5.2-5.4 meq/l (55%), 5.5-5.7 meq/l (21%), 5.8-6.0 meq/l (10%), >6.0 meq/l (14%)]. Of 31 patients (2 excluded due to brief PD time), 39% displayed hyperkalemia only, 23% displayed hypokalemia only, and the remainder (38%) displayed both or neither. Comparing hypokalemia-only with hyperkalemia-only patients, we found no difference in potassium chloride therapy, medications interrupting the renin-angiotensin system, small-molecule transport status, and renal urea clearance. We compared biochemical parameters from the hypokalemic and hyperkalemic serum samples and observed lower bicarbonate concentrations, higher creatinine concentrations, and higher urea nitrogen concentrations in the hyperkalemic samples (p < 0.001 for each), without difference in glucose concentrations.Conclusion. We observed hyperkalemia 3 times as frequently as hypokalemia in our PD population. High-potassium diet, PD noncompliance, increased muscle mass, potassium shifts, and/or the daytime period without PD might contribute to hyperkalemia.

Length of Interdialytic Intervals Affects Morbidity and Mortality in Chronic Haemodialysis Patients.

BACKGROUND: Chronic in-center hemodialysis (HD) patients may experience more morbidity and mortality after the weekend. Since our Veterans Administration Hospital HD unit is closed on the weekend, non-traditional HD schedules were created. Some schedules contained a 4-day weekend compared to the usual 3-day weekend. We hypothesized that there are more frequent cardiovascular events (CVEs) and higher mortality after longer interdialytic intervals. METHODS: Patients (n=85) were placed on HD schedules as they became available. The usual interdialytic interval group consisted of patients dialyzing on Mon-Wed-Fri or Mon-Tue-Fri (longest interdialytic gap 3 days, n=29), and the long interdialytic interval group consisted of patients dialyzing on Mon-Wed-Thu, Mon-Tue-Thu, Tue-Wed-Fri, or Tue-Thu-Fri (longest interdialytic gap 4 days, n=56). RESULTS: All-cause mortality was not different between groups, and CVEs occurred more frequently in the usual interdialytic interval group (maybe due to higher mean potassium and phosphorus concentrations). However, within each group, a similar pattern of CVE occurrence as a function of time after dialysis was observed. Compared to CVEs occurring during the 2 days after HD (the lowest frequency), CVEs occurred 2-3 times more frequently during and immediately after HD and 5-7 times more frequently during the third and fourth days after HD. The greatest risk of CVE occurred during the fourth day after HD, which exists only in the long interdialytic interval group. CONCLUSION: In chronic HD patients, CVEs are most likely to occur after the longest interdialytic intervals.

Angiotensin II receptors and peritoneal dialysis-induced peritoneal fibrosis.

The vasoactive hormone angiotensin II initiates its major hemodynamic effects through interaction with AT1 receptors, a member of the class of G protein-coupled receptors. Acting through its AT1R, angiotensin II regulates blood pressure and renal salt and water balance. Recent evidence points to additional pathological influences of activation of AT1R, in particular inflammation, fibrosis and atherosclerosis. The transcription factor nuclear factor κB, a key mediator in inflammation and atherosclerosis, can be activated by angiotensin II through a mechanism that may involve arrestin-dependent AT1 receptor internalization. Peritoneal dialysis is a therapeutic modality for treating patients with end-stage kidney disease. The effectiveness of peritoneal dialysis at removing waste from the circulation is compromised over time as a consequence of peritoneal dialysis-induced peritoneal fibrosis. The non-physiological dialysis solution used in peritoneal dialysis, i.e. highly concentrated, hyperosmotic glucose, acidic pH as well as large volumes infused into the peritoneal cavity, contributes to the development of fibrosis. Numerous trials have been conducted altering certain components of the peritoneal dialysis fluid in hopes of preventing or delaying the fibrotic response with limited success. We hypothesize that structural activation of AT1R by hyperosmotic peritoneal dialysis fluid activates the internalization process and subsequent signaling through the transcription factor nuclear factor κB, resulting in the generation of pro-fibrotic/pro-inflammatory mediators producing peritoneal fibrosis.

Administer but Do Not Dispense: Effect of Change in Medication Handling by Nurses on Outcomes of Home Dialysis Patients.

BACKGROUND: To come into compliance with South Carolina statute, we changed how nurses handle medications (antibiotics, erythropoietin [EPO], calcitriol and heparin) in our outpatient home dialysis clinic. Nurses continued to administer medications in the clinic but no longer dispensed medications for patients to take home; instead, medications were dispensed from pharmacies to the patients by mail. We hypothesized that the abovementioned change in medication handling worsened clinical outcomes. There is very little medical literature on this topic. MATERIALS AND METHODS: A retrospective case series of quality and safety in 31 patients in a community-based, medical center-affiliated home dialysis program was performed. We compared laboratory values and adverse clinical events relevant to the medications mentioned above during 4-8 months before and during 5 months after September 1, 2014 (the day when medication handling was changed). RESULTS: We observed no changes in the incidences of dialysis access dysfunction, access infections, antibiotic inaccessibility to patients for access-related infections, infection outcomes, parathyroid hormone concentrations, hemoglobin concentrations, monthly EPO dose and missed monthly clinic visits after September 1, 2014. However, we noted significantly fewer subcutaneous EPO administrations per month and less time between phlebotomy and laboratory review with patients by their nephrologists at monthly clinic visits after September 1, 2014. CONCLUSIONS: The change in handling of medications by nurses in our outpatient home dialysis program to comply with the state statute did not worsen patient outcomes relevant to the affected medications and in fact caused several unexpected improvements.

Clathrin-dependent internalization of the angiotensin II AT1A receptor links receptor internalization to COX-2 protein expression in rat aortic vascular smooth muscle cells.

The major effects of Angiotensin II (AngII) in vascular tissue are mediated by AngII AT1A receptor activation. Certain effects initiated by AT1A receptor activation require receptor internalization. In rat aortic vascular smooth muscle cells (RASMC), AngII stimulates cyclooxygenase 2 protein expression. We have previously shown this is mediated by ß-arrestin-dependent receptor internalization and NF-κB activation. In this study, a specific inhibitor of clathrin-mediated endocytosis (CME), pitstop-2, was used to test the hypothesis that clathrin-dependent internalization of activated AT1A receptor mediates NF-κB activation and subsequent cyclooxygenase 2 expression. Radioligand binding assays, real time qt-PCR and immunoblotting were used to document the effects of pitstop-2 on AngII binding and signaling in RASMC. Laser scanning confocal microscopy (LSCM) was used to image pitstop-2׳s effects on AT1 receptor/GFP internalization in HEK-293 cells and p65 NF-κB nuclear localization in RASMC. Pitstop-2 significantly inhibited internalization of AT1A receptor (44.7% ± 3.1% Control vs. 13.2% ± 8.3% Pitstop-2; n=3) as determined by radioligand binding studies in RASMC. Studies utilizing AT1A receptor/GFP expressed in HEK 293 cells and LSCM confirmed these findings. Pitstop-2 significantly inhibited AngII-induced p65 NF-κB phosphorylation and nuclear localization, COX-2 message and protein expression in RASMC without altering activation of p42/44 ERK or TNFα signaling. Pitstop-2, a specific inhibitor of clathrin-mediated endocytosis, confirms that internalization of activated AT1A receptor mediates AngII activation of cyclooxygenase 2 expression in RASMC. These data provide support for additional intracellular signaling pathways activated through ß-arrestin mediated internalization of G protein-coupled receptors, such as AT1A receptors.

Stimulation of Cyclooxygenase 2 Expression in Rat Peritoneal Mesothelial Cells.

Objective: Since peritoneal dialysis causes peritoneal fibrosis, we examined how glucose (osmotic factor), mannitol (osmotic control), and angiotensin II (AngII) regulate proinflammatory cyclooxygenase 2 (COX-2) in primary rat peritoneal mesothelial cells. Materials and Methods: For this study, we used the following material (n = 4-8 cell lines): cells, passages 1-2; 125I-AngII receptor surface binding (AT1R antagonist losartan, AT2R antagonist PD123319; both 10 µM); intracellular calcium probe calcium-5; COX-2 immunoblotting (ß-actin normalized); real-time PCR of COX-2 gene PTGS2, and NF-κB inhibitor Ro-1069920 (5 µM). Results: AngII surface receptors were predominantly AT1R (minimally AT2R). AngII and glucose increased COX-2 protein expression concentration dependently; mannitol also increased COX-2 expression. Maximal COX-2 protein expression was observed after 6 h (AngII) and 24 h (glucose, mannitol). The time course of increases in PTGS2 mRNA levels reflected that of COX-2 protein expression. At optimal exposure conditions (time/concentration), glucose was 5-fold more efficacious in stimulating COX-2 protein expression than AngII or mannitol. Losartan fully inhibited COX-2 protein responses to AngII and mannitol, but minimally inhibited responses to glucose. Ro-1069920 fully inhibited COX-2 protein responses to each effector. Conclusion: AngII, glucose, and osmotic stress (mannitol) activate COX-2; NF-κB may be an ideal site for COX-2 blockade, and COX-2 activation by osmotic stress requires AT1R, but activation by glucose is more robust and mechanistically complex. © 2014 S. Karger AG, Basel.

Angiotensin II activates NF-κB through AT1A receptor recruitment of ß-arrestin in cultured rat vascular smooth muscle cells.

Activation of the angiotensin type 1A receptor (AT1AR) in rat aorta vascular smooth muscle cells (RASMC) results in increased synthesis of the proinflammatory enzyme cyclooxygenase-2 (COX-2). We previously showed that nuclear localization of internalized AT1AR results in activation of transcription of the gene for COX-2, i.e., prostaglandin-endoperoxide synthase-2. Others have suggested that ANG II stimulation of COX-2 protein synthesis is mediated by NF-κB. The purpose of the present study was to examine the interrelationship between AT1AR activation, ß-arrestin recruitment, and NF-κB activation in the ability of ANG II to increase COX-2 protein synthesis in RASMC. In the present study we utilized RASMC, inhibitors of the NF-κB pathway, ß-arrestin knockdown, radioligand binding, immunoblotting, and immunofluorescence to characterize the roles of AT1AR internalization, NF-κB activation, and ß-arrestin in ANG II-induced COX-2 synthesis. Ro-106-9920 or parthenolide, agents that inhibit the initial steps of NF-κB activation, blocked ANG II-induced p65 NF-κB nuclear localization, COX-2 protein expression, ß-arrestin recruitment, and AT1AR internalization without inhibiting ANG II-induced p42/44 ERK activation. Curcumin, an inhibitor of NF-κB-induced transcription, blocked ANG II-induced COX-2 protein expression without altering AT1AR internalization, ANG II-induced p65 NF-κB nuclear localization, or p42/44 ERK activation. Small interfering RNA-induced knockdown of ß-arrestin-1 and -2 inhibited ANG II-induced p65 NF-κB nuclear localization. In vascular smooth muscle cells, internalization of the activated AT1AR mediated by ß-arrestins activates the NF-κB pathway, producing nuclear localization of the transcription factor and initiation of COX-2 protein synthesis, thereby linking internalization of the receptor with the NF-κB pathway.

Peritonitis from Mycobacterium wolinskyi in a chronic peritoneal dialysis patient.

We report the case of acute peritonitis caused by a rapidly growing mycobacterium in a chronic peritoneal dialysis patient, whose renal failure had been caused by diabetic glomerulosclerosis. The organism cultured from the peritoneal dialysis fluid was Mycobacterium wolinskyi. Peritonitis caused by M. wolinskyi in a chronic peritoneal dialysis patient has never been reported before.

Utility of percutaneous renal biopsy in chronic kidney disease.

BACKGROUND: We tested the hypothesis that patterns of serum creatinine concentrations (S-cr) prior to percutaneous renal biopsy (PRB) predict the utility of PRB in safely making renal diagnoses, revealing treatable disease, and altering therapy in chronic kidney disease patients. METHODS: PRB specimens (170 patients) were assigned to 1 of 5 groups: S-cr never greater than 0.11 mM for at least 6 months prior to PRB (Group 1); S-cr greater than 0.11 mM but less than 0.18 mM during the 6 months prior to PRB (Groups 2); S-cr less than 0.18 mM during the 6 months prior to PRB but greater than 0.18 mM prior to these 6 months (Group 3); S-cr greater than 0.18 mM for less than 6 months prior to PRB (Group 4); S-cr greater than 0.18 mM for more than 6 months prior to PRB (Group 5). RESULTS: Histopathology chronicity score (0-9) increased with increasing group number: 2.1 (Group 1); 4.4 (Group 2); 4.5 (Group 3); 5.4 (Group 4); 7.0 (Group 5). Post-PRB bleeding was more common with increasing group number. New therapy was instituted after PRB most frequently in Group 4 (62%) and least frequently in Group 5 (24%). CONCLUSION: After more prolonged elevations of S-cr, PRB may be less safe and less likely to reveal treatable disease and opportunities for therapy.

Angiotensin II-induced cyclooxygenase 2 expression in rat aorta vascular smooth muscle cells does not require heterotrimeric G protein activation.

Angiotensin II (AngII) initiates cellular effects via its G protein-coupled angiotensin 1 (AT(1)) receptor (AT(1)R). Previously, we showed that AngII-induced expression of the prostanoid-producing enzyme cyclooxygenase 2 (COX-2) was dependent upon nuclear trafficking of activated AT(1)R. In the present study, mastoparan (an activator of G proteins), suramin (an inhibitor of G proteins), 1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122; a specific inhibitor of phospholipase C), and sarcosine(1)-Ile(4)-Ile(8)-AngII (SII-AngII; a G protein-independent AT(1)R agonist) were used to determine the involvement of G proteins and AT(1A)R trafficking in AngII-stimulated COX-2 protein expression in human embryonic kidney-293 cells stably expressing AT(1A)/green fluorescent protein receptors and cultured vascular smooth muscle cells, respectively. Mastoparan alone stimulated release of intracellular calcium and increased COX-2 expression. Preincubation with mastoparan inhibited AngII-induced calcium signaling without altering AngII-induced AT(1A)R trafficking, p42/44 extracellular signal-regulated kinase (ERK) activation, or COX-2 expression. Suramin or U73122 had no significant effect on their own; they did not inhibit AngII-induced AT(1A)R trafficking, p42/44 ERK activation, or COX-2 expression; but they did inhibit AngII-induced calcium responses. SII-AngII stimulated AT(1A)R trafficking and increased COX-2 protein expression without activating intracellular calcium release. These data suggest that G protein activation results in increased COX-2 protein expression, but AngII-induced COX-2 expression seems to occur independently of G protein activation.

Thiol antioxidants regulate angiotensin II AT1 and arginine vasopressin V1 receptor functions differently in vascular smooth muscle cells.

BACKGROUND: We compared the effects of the sulfhydryl-containing (thiol) antioxidant dithiothreitol (DTT), which disrupts disulfide bonds, on cell signaling through angiotensin II (AngII) Type 1 receptors (AT1Rs) and arginine vasopressin (AVP) V1 receptors (V1Rs). The AT1R contains two extracellular disulfides bonds but its ligand contains none, whereas the V1R contains no extracellular disufides bonds but its ligand contains 1. METHODS: We measured radioligand binding, intracellular calcium responses, and extracellular signal-regulated kinase phosphorylation in cultured rat aortic vascular smooth muscle cells and alterations in urine osmolality in intact rats. RESULTS: Preincubation of cells with DTT, a maneuver designed to target receptor disulfides, resulted in concentration-dependent decreases in specific (125)I-AngII binding to AT1Rs and acute angiotensin-stimulated intracellular calcium mobilization but no decreases in specific (125)I-AVP binding to V1Rs or AVP-stimulated intracellular calcium mobilization. In contrast, preincubation of the ligands with DTT followed by acute exposure to the cells, a maneuver designed to target ligand disulfides, blunted calcium mobilization to AVP robustly but to AngII only minimally. In intact rats, the increase in urine osmolality caused by subcutaneous injection with the AVP analogue desmopressin was significantly diminished when the analogue was preincubated with an excess of DTT. CONCLUSION: DTT inhibits cell signaling to AngII AT1Rs and AVP V1Rs, at least in part through disruption of disulfide linkages, but the pattern of response depends upon whether disulfides of ligand or receptor are targeted.

COX-2 expression stimulated by Angiotensin II depends upon AT1 receptor internalization in vascular smooth muscle cells.

Previously, we demonstrated that nuclear localization of the Angiotensin II AT1A receptor was associated with the activation of transcription for the COX-2 gene, PTGS-2. The hypothesis of the present study is that AT1AR internalization from the plasma membrane is a first step in the nuclear localization of the endogenous AT1AR of rat aortic vascular smooth muscle cells and the resultant increase of COX-2 protein expression. Angiotensin II produced both a time- and concentration-dependent increase in COX-2 protein expression in these cells. Treatment with sucrose or phenylarsine oxide, inhibitors of receptor internalization, significantly inhibited AT1AR internalization and abolished the increase in COX-2 protein produced by Angiotensin II without affecting COX-2 expression on its own. Sucrose pre-treatment of rat aortic vascular smooth muscle cells resulted in an increase in p42/44 and p38 activation, while phenylarsine oxide pre-treatment activated only p38 kinase without inhibiting activation of p42/44 produced by Angiotensin II. These results demonstrate that inhibiting the internalization of the AT1AR results in a loss of ability of Angiotensin II to increase the protein expression of COX-2, thus supporting previous work showing a relationship between AT1AR nuclear localization and activation of COX-2 gene expression. Surprisingly, in contrast to other studies, the data also indicates that activation of p42/44 and/or p38 does not correlate with the increased expression of COX-2.