Universal Urine Drug Screening with Rapid Confirmation upon Admission to Labor and Delivery.

OBJECTIVE: This study aimed to describe our experience with universal urine drug screening (UDS) with rapid confirmation (RC) via liquid chromatography mass spectrometry (LC-MS) before infant's discharge, in efforts to increase detection of neonates at risk of neonatal opioid withdrawal syndrome (NOWS) while reducing patient burden related to false positive results. STUDY DESIGN: Two-phase retrospective study of all pregnant women admitted to our labor and delivery (L&D) unit before (phase 1, April 2018-March 2019) and after (phase 2, October 2019-September 2020) RC of UDS was initiated. Urine samples were obtained on admission and screened for drugs using an enzyme immunoassay with positive results reflexed to confirmation via LC-MS. The turnaround time for LC-MS was 1 week in phase 1 and 24 hours in phase 2. For mothers with positive LC-MS confirmation, the infant's meconium was sent for drug screening. Positive results were determined to be true or false positive based on urinary LC-MS results. The primary outcome was the rate of opioid-positive mothers who were unanticipated. The secondary outcome was the difference in rate of neonates who were observed for NOWS, before and after implementation of RC with LC-MS. RESULTS: In phase 2, a total of 2,395 deliveries occurred of which 2,122 (88.6%) had available UDS results. Fifty-two (2.5%) women had a positive UDS for at least one drug with LC-MS confirmation. Of those, 25 were true positive and 27 were false positive. Twenty-one (84%) true positive mothers were taking opioids and 8 (37%) of them were unanticipated positives. Among mothers with positive UDS for opioids, the neonatal observation rate for development of NOWS was 100% (22/22) and 48% (21/44) before and after implementation of LC-MS RC, respectively. CONCLUSION: Universal UDS and LC-MS RC in L&D may improve detection of unanticipated positive mothers whose infants are at risk of NOWS. RC of positive results allows intervention only for confirmed cases. KEY POINTS: · Universal UDS can detect more infants at risk of NOWS.. · Rapid confirmation of positive UDS reduces burden.. · Only confirmed infants should be observed in the neonatal intensive care unit.. · Child Protective Services should only be notified of confirmed opioid-positive results..

Urinary Tract Infections in Low Birth Weight Neonates.

OBJECTIVE: Our objective was to evaluate the incidence of urinary tract infections (UTIs) in low birth weight (LBW) neonates and to evaluate the compliance of neonatal intensive care unit (NICU) providers in performing urine cultures as a part of late-onset sepsis (LOS) evaluations following an educational intervention. STUDY DESIGN: A retrospective chart review for all LBW infants undergoing LOS evaluations was performed. An educational intervention was conducted to encourage NICU providers to perform urine cultures in LOS evaluations. Prospective chart reviews were conducted following the intervention to assess compliance with the urine culture directive and the incidence of UTIs before and after the intervention. RESULTS: Rate of UTIs among LBW neonates was 1.3% for the entire study period and typical uropathogens were the cause. UTIs were found concurrently with bacteremia in only 33.3% of cases and showed a predilection for male infants when analyzing based on the number of infections. Urine cultures were performed in 20% of LOS evaluations prior to our educational intervention and increased to 57% (p < 0.0001) postintervention. CONCLUSION: An educational intervention is effective at increasing the rate of obtaining urine cultures with LOS evaluations. Performing these cultures reveals that UTIs in LBW neonates are common without bacteremia and can be missed if they are omitted from LOS evaluations. KEY POINTS: · UTIs occur often in preterm infants, especially boys.. · Education increases the performance of urine cultures.. · UTIs in preterm infants occur often without bacteremia..

Are Early-Onset Sepsis Evaluations and Empiric Antibiotics Mandatory for All Neonates Admitted with Respiratory Distress?

OBJECTIVE: The objective of this study was to evaluate the success and safety of an antimicrobial stewardship protocol for neonates admitted with respiratory distress at birth. STUDY DESIGN: A retrospective cohort analysis of all infants admitted to the neonatal intensive care unit (NICU) with respiratory distress from January 2013 to February 2018 was conducted. In April 2016, an antimicrobial stewardship protocol was implemented, dividing neonates into two groups: maternal indications for delivery (no infectious risk factors for early-onset sepsis [EOS]) and fetal indications (risk factors present) for delivery. Neonates with risk factors for EOS were started on empiric antibiotics, those who lacked risk factors were observed. Paired sample t-test and descriptive statistics were used to compare the pre- and postprotocol implementation. RESULTS: There were no missed cases of EOS in our study. Management with empiric antibiotics decreased from 95 to 41% of neonates with respiratory distress after initiation of the protocol. Newborns with a lower mean (±standard errors of the mean [SEM]) gestational age were more likely to receive empiric antibiotics (35.1 ± 0.4 [range: 23-42 weeks] vs. 37.7 ± 0.2 weeks [range: 24-42 weeks]; p < 0.05). Similar findings were seen for neonates with lower mean birth weights (2,627 ± 77 [range: 390-5,440 g] vs. 3,078 ± 51 g [range: 620-6,260 g]; p < 0.05). CONCLUSION: The antibiotic stewardship protocol safely reduces the administration of empiric antibiotics to symptomatic neonates without missing any cases of sepsis. KEY POINTS: · Newborns born with respiratory distress often receive broad-spectrum antibiotics upon NICU admission.. · An antibiotic stewardship program was created for this population and considered perinatal risk factors for sepsis when determining whether antibiotics were indicated.. · This antibiotic stewardship program was safe and effective, significantly reducing antibiotic use without missing any cases of sepsis..

Pediatric Research and Scholarship Committee: Single Institution Initiative to Enhance Scholarly Activity of Pediatric Residents.

OBJECTIVE: We sought to improve scholarly activity of pediatric residents by providing residents with support and guidance from a committee of faculty and staff members dedicated to advancing research within the program while requiring minimal additional funding or resources. APPROACH: Established in 2012, the Pediatric Research and Scholarship Committee (PRSC) ascertained research interests of pediatric residents and matched residents with scholarly activity mentors based on mutual interests and goals. We measured change in scholarly activity of residents after the development of the PRSC by reviewing resident presentations at national/regional meetings and manuscripts published pre- and post-PRSC. OUTCOMES: The average number of conference presentations at regional/national meetings per resident ratio increased from 0.13 over the 2 years prior to the PRSC to an average of 0.34 over the 2 years post-PRSC, with the overall increase sustained over the seven years post-PRSC (0.13 pre-PRSC vs 0.48 post-PRSC, P < .01). In addition, published peer-reviewed manuscripts with resident primary authorship increased after the initiation of the PRSC from 0 publications over the 2 years pre-PRSC to a total of 25 publications over the 7 years post-PRSC (P = .01). An average of 27% of graduating residents with limited PRSC exposure (2 graduating classes) had presented at a regional/national conference during residency, as compared to 50% of graduating residents over the first 2 years of full PRSC exposure, and 59% of all graduating residents with full exposure to the PRSC over the last 5 years (P = .03). DISCUSSION: Implementation of a research committee comprised of dedicated faculty can play a vital role in stimulating and sustaining productivity in resident research and scholarly activity. Our model can be adopted by other residency programs seeking to advance resident scholarly activities.

Occipital mass in antenatal sonography.

Biophysical profile (BPP) with ultrasound performed for a 32-year-old G5P3013 admitted at 31 weeks gestation with preterm, premature rupture of membranes (PPROM) noted an extracalvarial mass concerning for an encephalocele. Fetal MRI demonstrated edema over the occiput with no definable lesion visualized. Preterm labor requiring Cesarean delivery resulted in a live male neonate at 33 weeks gestation. An occipital mass was observed on neonatal physical exam. Postnatal ultrasound and MRI were consistent with cephalohematoma. This was surprising given the lack of vaginal delivery. We hypothesize that the occiput was positioned against the maternal ischial tuberosity and developed chronic trauma secondary to normal fetal movement over time, resulting in a cephalohematoma. Postnatal imaging confirmed this diagnosis as the mass gradually decreased and ultimately resolved. Although other etiologies are possible, this case emphasizes the need to consider cephalohematoma in the differential of CNS masses during pregnancy without abdominal trauma and/or vaginal delivery.

Who's counting? Assessing the effects of a simulation-based training intervention on the accuracy of neonatal heart rate auscultation.

OBJECTIVE: To determine if simulation-based medical education could improve pediatric residents' ability to accurately assess neonatal heart rate via auscultation. STUDY DESIGN: Primary outcomes included heart rate accuracy and Neonatal Resuscitation Program (NRP) group accuracy, defined as whether a heart rate estimation fell in the appropriate NRP algorithm group. Pediatric residents completed a pre-assessment and then participated in a simulation training intervention on high-fidelity manikins. Residents completed a post-assessment 1 month later. RESULTS: Heart rate estimates from 21 pediatric residents showed improved overall heart rate accuracy and NRP group accuracy from 53.6 to 78.7% (p < 0.0001) and 68.3 to 80% (p = 0.0002), respectively. Residents were more likely to overestimate low heart rates and underestimate high heart rates. CONCLUSION: Heart rate simulation-based training significantly improved residents' ability to assess heart rate on high-fidelity neonatal manikins. Providers participating in NRP may benefit by receiving heart rate skills assessment-focused training during an NRP provider course.

Another Case of Multilevel Cervical Disconnection Syndrome Presenting as Neonatal Encephalopathy.

Multilevel cervical disconnection syndrome (MCDS) is a rare malformation of the cervical spine previously documented in two toddlers. We present a case of a newborn first thought to have hypoxic-ischemic encephalopathy who was subsequently diagnosed with MCDS. The possibility of in utero presentation of the syndrome in this patient and the categorization of this syndrome in the spectrum of basilar skull/upper cervical malformation syndromes is discussed.

Factors Associated with Supplemental Formula Feeding of Breastfeeding Infants During Postpartum Hospital Stay.

OBJECTIVE: To determine reasons potentially amenable to interventions that mothers choose to supplement breastfeeding with formula in the immediate postpartum period. STUDY DESIGN: We distributed surveys to all mothers in the postpartum unit who delivered a live newborn on day of maternal discharge to assess feeding behaviors during their inpatient admission. We evaluated, when applicable, their reasons for supplementation and examined cultural and demographic information to uncover trends for formula use and potential areas for provider intervention. RESULTS: Seven hundred twelve of 1,400 mothers responded, of which 478 (65%) reported supplementing breastfeeding with formula (BF+F). The most common reasons for formula supplementation were perception of inadequate milk supply (36.4%), desire for sleep (35.4%), and a plan to breast and bottle feed (35.2%). Exclusive breastfeeding (EBF) was associated with primiparous status (OR 1.95; 95% CI 1.3-3.0), higher education level (OR 2.6; 95% CI 1.7-3.9), and having been breastfed as an infant (OR 1.54; 95% CI 1-2.37). Mothers who experienced skin-to-skin contact also had higher rates of EBF (29.5% versus 19.9%). Factors associated with exclusive formula feeding included single marital status, birth of mother in the United States, Catholic religion, multiparity, and cesarean delivery. Religious and cultural factors also played important roles in maternal feeding behaviors. CONCLUSION: Clinicians can anticipate risk factors for formula use in mothers who plan to breastfeed and tailor counseling appropriately to increase EBF rates.

Variables associated with the decreased risk of intraventricular haemorrhage in a large sample of neonates with respiratory distress syndrome.

OBJECTIVE: Prematurity and other risk factors are associated with the development of intraventricular haemorrhage (IVH) in newborns with respiratory distress syndrome (RDS). Conversely, further analysis can determine what characteristics might be associated with a decreased risk of IVH. STUDY DESIGN: By using International Classification of Diseases, Ninth Revision, Clinical Modification codes from data obtained from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project from 2000 to 2009, we identified a large number of cases of RDS. Multivariable logistic regression analysis identified potential variables associated with decreased risk of IVH. RESULT: Our cohort included 194 621 neonates with RDS, of whom 20 386 (10.5%) developed IVH. Variables associated with decreased risk of both all grades of IVH and severe IVH only included infant of diabetic mother (IDM) status (OR 0.62 (0.54 to 0.70), p<0.001; OR 0.56 (0.42 to 0.74), p<0.001), Trisomy 21 (OR 0.45 (0.30 to 0.69), p<0.001; OR 0.38 (0.16 to 0.93), p=0.034), maternal hypertension (OR 0.62 (0.53 to 0.72), p<0.001; OR 0.28 (0.18 to 0.43), p<0.001), caesarean birth (OR 0.79 (0.74 to 0.84), p<0.001; OR 0.83 (0.73 to 0.94), p<0.001) and, consistent with prior studies, female gender (OR 0.85 (0.82 to 0.88), p<0.001; OR 0.76 (0.72 to 0.80), p<0.001). Polycythaemia (OR 0.67 (0.49 to 0.92), p=0.013; OR 0.79 (0.43 to 1.45), p=0.449) and hypothermia (OR 0.86 (0.75 to 0.99), p=0.039; OR 1.01 (0.81 to 1.28), p=0.903) were associated with lower risk of all IVH but not severe IVH only. CONCLUSIONS: Previous associations with IVH such as lower birth weight were confirmed. However, infants in whom new variables such as IDM status were present were less likely to develop all IVH grades. Further analysis of these potential protective variables is necessary to better understand the pathophysiology of IVH.

A 0.7 Mb de novo duplication at 7q21.3 including the genes DLX5 and DLX6 in a patient with split-hand/split-foot malformation.

Split-hand/split-foot malformation (SHFM1) has been reported to be caused by deletions, duplications or rearrangements involving the 7q21.3 region harboring DSS1, DLX5, and DLX6. We report on a female patient with unilateral syndactyly of the third and fourth fingers of the right hand and overgrowth and lateral deviation of the right great toe. There was a split foot malformation on the right, with absent fifth toe. The left hand was apparently normal and left foot was intact. The patient has no hearing loss. We performed conventional G-banding karyotype analysis, array comparative genomic hybridization (aCGH) and fluorescence in situ hybridization (FISH). G-banding karyotype result was normal 46,XX. However, a duplication of 719 kb (96,303,736-97,022,335; NCBI build36/hg18, March 2006) was identified at the 7q21.3 region by aCGH. The array result was also confirmed by FISH analysis. The duplicated region harbors only DLX5 and DLX6, which are known for their role in SHFM1. Additionally, FISH analysis of parental samples showed de novo origin of this abnormality in the patient. This is the first report that highlights the duplication of 719 kb at 7q21.3, harboring only DLX5 and DLX6 associated with the SHFM1 phenotype.

Transfusion-related acute gut injury: feeding, flora, flow, and barrier defense.

TRAGI (transfusion-related acute gut injury) is an acronym we proposed to characterize a severe neonatal gastrointestinal reaction temporally related to a transfusion of packed blood red cells (PRBCs) for anemia in very low birth weights. The following are in support of a causative relationship: (1) the timing of necrotizing enterocolitis after a PRBC transfusion not being random, (2) traditional risk factors for necrotizing enterocolitis are often absent, (3) significant anemia appears to be a universal finding, (4) the age of donor blood is often slightly older than controls, (5) TRAGI is not postnatal age dependent, and (6) TRAGI does not show a centering at 31 weeks' postconceptual age as does nontransfusion-related NEC. Although TRAGI is linked to the timing of PRBC transfusions, we propose a novel hypothesis that the convergence at 31 weeks' postconceptual age for classic NEC approximates the age of presentation of other oxygen delivery and neovascularization syndromes (eg, retinopathy of prematurity), suggesting its etiologic link to a generalized systemic maturational mechanism or another common developmental theme. This report will begin by reviewing the history of the clinical presentation and discovery of TRAGI and will then analyze various pathophysiologic mechanisms that may account for the phenomenon when clinicians render therapies. We will end by a call to action for randomized clinical trials to test various etiologic theories.

Transfusion-related acute gut injury: necrotizing enterocolitis in very low birth weight neonates after packed red blood cell transfusion.

OBJECTIVE: This is a repeat cohort study in which we sought to determine whether an association of necrotizing enterocolitis (NEC) <48 hours of a packed red blood cells (PRBC) transfusion was a prior sampling artifact. STUDY DESIGN: All very low birth weight neonates with NEC Stage ≥ IIB admitted over an 18-month period were categorized for NEC: (1) <48 hours after a PRBC transfusion; (2) unrelated to the timing of PRBCs; and (3) never transfused. RESULTS: Eight hundred eighty-three admissions over 18 months were reviewed; 256 were very low birth weight that resulted in 36 NEC cases and 25% were associated with PRBC (n = 9). PRBC-associated cases had lower birth weight, hematocrit, and rapid onset of signs (<5 hours). The timing of association of PRBC transfusion and NEC differed from random, showing a distribution that was not uniform over time (χ(2) = 170.7, df = 40; P < .000001) consistent with the possibility of a causative relationship in certain cases of NEC. Current weight at onset of NEC did not differ; however, the more immature the neonate the later the onset of NEC creating a curious centering of occurrence at a median of 31 weeks postconceptual age. CONCLUSIONS: We conclude that PRBC-related NEC exists. Transfusion-related acute gut injury is an acronym we propose to characterize a severe neonatal gastrointestinal reaction proximal to a transfusion of PRBCs for anemia. The convergence at 31 weeks postconceptual age approximates the age of presentation of other O(2) delivery and neovascularization syndromes, suggesting a link to a generalized systemic maturational mechanism.

Effects of protein/nonprotein caloric intake on parenteral nutrition associated cholestasis in premature infants weighing 600-1000 grams.

BACKGROUND: Parenteral nutrition-associated cholestasis (PNAC) has historically been a significant cause of morbidity and mortality in neonates undergoing parenteral feeding. Studies examining the causes of cholestasis in the PN-dependent neonate have produced a wide range of data, with some conflicting results. Increased protein/nonprotein calorie ratios, increased glucose concentrations, and increased lipid concentrations have all been implicated as possible causes of PNAC. However, these studies were done in the pre-TrophAmine (neonatal-specific amino acid parenteral nutrition [PN] formulation) era. With the introduction of TrophAmine, infants are now receiving higher concentrations of protein, often being advanced rapidly even when nonprotein calories may not be sufficiently advanced to meet the infants' caloric needs. To the best of our knowledge, no studies have been conducted to evaluate the protein/nonprotein calorie ratio as a cause of PNAC in the TrophAmine era. METHODS: A retrospective chart review of 25 cholestatic and 25 noncholestatic PN-dependent premature neonates was conducted. All neonates weighed between 600 and 1000 g. Cholestasis was defined as a serum total bilirubin (TB) >or=2.0 mg/dL, with a serum direct bilirubin (DB) >or=20% of the TB. Neonates with major congenital anomalies or who underwent major surgery were excluded. PN macronutrient compositions were analyzed to examine if the different amounts of protein concentrations and protein/nonprotein calorie ratios played a role in the development of PNAC. Statistical analysis was performed using Student's t-tests. p Values < .05 were considered statistically significant. RESULTS: All measured nutrition parameters did not differ significantly between the cholestatic and noncholestatic groups. Protein intake, the protein/nonprotein calorie ratio, and renal function as evaluated by blood urea nitrogen (BUN) and creatinine did not differ between the 2 study groups. The only parameters that differed significantly between the groups were the duration of PN therapy and length of hospital stay. CONCLUSIONS: Protein to nonprotein calorie ratio was not an etiology in the development of cholestasis in infants (600-1000 g) receiving PN. Renal function elicited not to have an impact on cholestasis status of these infants. Therefore, providing adequate protein calories should not be limited in this patient population, as suggested by previous studies in the pre-TrophAmine era. We found that increased duration of PN therapy and increased length of hospital stay were associated with PNAC.

Acute antihypertensive action of nitroxides in the spontaneously hypertensive rat.

Tempol is an amphipathic radical nitroxide (N) that acutely reduces blood pressure (BP) and heart rate (HR) in the spontaneously hypertensive rat (SHR). We investigated the hypothesis that the response to nitroxides is determined by SOD mimetic activity or lipophilicity. Groups (n = 6-10) of anesthetized SHRs received graded intravenous doses of Ns: tempol (T), 4-amino-tempo (AT), 4-oxo-tempo (OT), 4-trimethylammonium-2,2,6,6-tetramethylpiperidine-1-oxyl iodide (CAT-1), 3-carbamoyl-proxyl (3-CP), or 3-carboxy-proxyl (3-CTPY). Others received native or liposomal (L) Cu/Zn SOD. T and OT are uncharged, AT is positively charged and cell-permeable, and CAT-1 is positively charged and cell-impermeable. 3-CP and 3-CTPY have five-member pyrrolidine rings, whereas T, AT, OT, and CAT-1 have six-member piperidine rings. T and AT reduced mean arterial pressure (MAP) similarly (-48 +/- 2 mmHg and -55 +/- 8 mmHg) but more (P < 0.05) than OT and CAT-1. 3-CP and 3-CTPY were ineffective. The group mean change in MAP with piperidine Ns correlated with SOD activity (r = -0.94), whereas their ED(50) correlated with lipophilicity (r = 0.89). SOD and L-SOD did not lower BP acutely but reduced it after 90 min (-32 +/- 5 and -31 +/- 6 mmHg; P < 0.05 vs. vehicle). Pyrrolidine nitroxides are ineffective antihypertensive agents. The antihypertensive response to piperidine Ns is predicted by SOD mimetic action, and the sensitivity of response is by hydrophilicity. SOD exerts a delayed hypotensive action that is not enhanced by liposome encapsulation, suggesting it must diffuse to an extravascular site.

Antihypertensive response to prolonged tempol in the spontaneously hypertensive rat.

INTRODUCTION: Tempol is a permeant nitroxide superoxide dismutase (SOD) mimetic that lowers mean arterial pressure (MAP) in spontaneously hypertensive rats (SHRs). We investigated the hypothesis that the antihypertensive response entails a negative salt balance, blunting of plasma renin activity (PRA), endothelin-1 (ET-1), or catecholamines or correction of oxidative stress as indexed by 8-isoprostane prostaglandin F(2alpha) (PGF(2alpha)) (8-Iso). METHODS: Groups (N= 6 to 8) of SHRs were infused for 2 weeks with vehicle or tempol (200 nmol/kg/min) or given tempol (2 mmol/L) in drinking water. RESULTS: Tempol infusion reduced the MAP of anesthetized SHRs (150 +/- 5 vs. 126 +/- 6 mm Hg) (P < 0.005). Oral tempol did not change the heart rate but reduced the MAP of conscious SHRs (-23 +/- 6 mm Hg) (P < 0.01) but not Wistar-Kyoto (WKY) rats. Tempol infusion increased the PRA (2.2 +/- 0.2 vs. 5.0 +/- 0.9 ng/mL/hour) (P < 0.005), did not change excretion of nitric oxide (NO) [NO(2)+ NO(3) (NOx)], ET-1, or catecholamines but reduced excretion of 8-Iso (13.2 +/- 1.4 vs. 9.6 +/- 0.9 ng/24 hours; P < 0.01). Cumulative Na(+) balance and gain in body weight were unaltered by tempol infusion. Tempol prevented a rise in MAP with high salt intake. CONCLUSION: Tempol corrects hypertension without a compensatory sympathoadrenal activation or salt retention. The response is independent of nitric oxide, endothelin, or catecholamines and occurs despite increased PRA. It is accompanied by a reduction in oxidative stress and is maintained during increased salt intake.

Angiotensin-induced defects in renal oxygenation: role of oxidative stress.

We tested the hypothesis that superoxide anion (O(2)(-).) generated in the kidney by prolonged angiotensin II (ANG II) reduces renal cortical Po(2) and the use of O(2) for tubular sodium transport (T(Na):Q(O(2))). Groups (n = 8-11) of rats received angiotensin II (ANG II, 200 ng.kg(-1).min(-1) sc) or vehicle for 2 wk with concurrent infusions of a permeant nitroxide SOD mimetic 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (Tempol, 200 nmol.kg(-1).min(-1)) or vehicle. Rats were studied under anesthesia with measurements of renal oxygen usage and Po(2) in the cortex and tubules with a glass electrode. Compared with vehicle, ANG II increased mean arterial pressure (107 +/- 4 vs. 146 +/- 6 mmHg; P < 0.001), renal vascular resistance (42 +/- 3 vs. 65 +/- 7 mmHg.ml(-1).min(-1).100 g(-1); P < 0.001), renal cortical NADPH oxidase activity (2.3 +/- 0.2 vs. 3.6 +/- 0.4 nmol O(2)(-)..min(-1).mg(-1) protein; P < 0.05), mRNA and protein expression for p22(phox) (2.1- and 1.8-fold respectively; P < 0.05) and reduced the mRNA for extracellular (EC)-SOD (-1.8 fold; P < 0.05). ANG II reduced the Po(2) in the proximal tubule (39 +/- 1 vs. 34 +/- 2 mmHg; P < 0.05) and throughout the cortex and reduced the T(Na):Q(O(2)) (17 +/- 1 vs. 9 +/- 2 mumol/mumol; P < 0.001). Tempol blunted or prevented all these effects of ANG II. The effects of prolonged ANG II to cause hypertension, renal vasoconstriction, renal cortical hypoxia, and reduced efficiency of O(2) usage for Na(+) transport, activation of NADPH oxidase, increased expression of p22(phox), and reduced expression of EC-SOD can be ascribed to O(2)(-). generation because they are prevented by an SOD mimetic.

Salt intake, oxidative stress, and renal expression of NADPH oxidase and superoxide dismutase.

The hypothesis that a high salt (HS) intake increases oxidative stress was investigated and was related to renal cortical expression of NAD(P)H oxidase and superoxide dismutase (SOD). 8-Isoprostane PGF(2alpha) and malonyldialdehyde were measured in groups (n = 6 to 8) of conscious rats during low-salt, normal-salt, or HS diets. NADPH- and NADH-stimulated superoxide anion (O(2)(.-)) generation was assessed by chemiluminescence, and expression of NAD(P)H oxidase and SOD were assessed with real-time PCR. Excretion of 8-isoprostane and malonyldialdehyde increased incrementally two- to threefold with salt intake (P < 0.001), whereas prostaglandin E(2) was unchanged. Renal cortical NADH- and NADPH-stimulable O(2)(.-) generation increased (P < 0.05) 30 to 40% with salt intake. Compared with low-salt diet, HS significantly (P < 0.005) increased renal cortical mRNA expression of gp91(phox) and p47(phox) and decreased expression of intracellular CuZn (IC)-SOD and mitochondrial (Mn)-SOD. Despite suppression of the renin-angiotensin system, salt loading enhances oxidative stress. This is accompanied by increased renal cortical NADH and NADPH oxidase activity and increased expression of gp91(phox) and p47(phox) and decreased IC- and Mn-SOD. Thus, salt intake enhances generation of O(2)(.-) accompanied by enhanced renal expression and activity of NAD(P)H oxidase with diminished renal expression of IC- and Mn-SOD.

Effects of ANG II type 1 and 2 receptors on oxidative stress, renal NADPH oxidase, and SOD expression.

Oxidative stress accompanies angiotensin (ANG) II infusion, but the role of ANG type 1 vs. type 2 receptors (AT1-R and AT2-R, respectively) is unknown. We infused ANG II subcutaneously in rats for 1 wk. Excretion of 8-isoprostaglandin F2alpha (8-Iso) and malonyldialdehyde (MDA) were related to renal cortical mRNA abundance for subunits of NADPH oxidase and superoxide dismutases (SODs) using real-time PCR. Subsets of ANG II-infused rats were given the AT1-R antagonist candesartan cilexetil (Cand) or the AT2-R antagonist PD-123,319 (PD). Compared to vehicle (Veh), ANG II increased 8-Iso excretion by 41% (Veh, 5.4 +/- 0.8 vs. ANG II, 7.6 +/- 0.5 pg/24 h; P < 0.05). This was prevented by Cand (5.6 +/- 0.5 pg/24 h; P < 0.05) and increased by PD (15.8 +/- 2.0 pg/24 h; P < 0.005). There were similar changes in MDA excretion. Compared to Veh, ANG II significantly (P < 0.005) increased the renal cortical mRNA expression of p22phox (twofold), Nox-1 (2.6-fold), and Mn-SOD (1.5-fold) and decreased expression of Nox-4 (2.1-fold) and extracellular (EC)-SOD (2.1-fold). Cand prevented all of these changes except for the increase in Mn-SOD. PD accentuated changes in p22phox and Nox-1 and increased p67phox. We conclude that ANG II infusion stimulates oxidative stress via AT1-R, which increases the renal cortical mRNA expression of p22phox and Nox-1 and reduces abundance of Nox-4 and EC-SOD. This is offset by strong protective effects of AT2-R, which are accompanied by decreased expression of p22phox, Nox-1, and p67phox.