Pearl Chang

Deaf1 isoforms control the expression of genes encoding peripheral tissue antigens in the pancreatic lymph nodes during type 1 diabetes

Type 1 diabetes may result from a breakdown in peripheral tolerance that is partially controlled by the expression of peripheral tissue antigens (PTAs) in lymph nodes. Here we show that the transcriptional regulator Deaf1 controls the expression of genes encoding PTAs in the pancreatic lymph nodes (PLNs). The expression of canonical Deaf1 was lower, whereas that of an alternatively spliced variant was higher, during the onset of destructive insulitis in the PLNs of nonobese diabetic (NOD) mice. We identified an equivalent variant Deaf1 isoform in the PLNs of patients with type 1 diabetes. Both the NOD mouse and human Deaf1 variant isoforms suppressed PTA expression by inhibiting the transcriptional activity of canonical Deaf1. Lower PTA expression resulting from the alternative splicing of DEAF1 may contribute to the pathogenesis of type 1 diabetes.

Over-expression of antioxidant enzymes protects cultured hippocampal and cortical neurons from necrotic insults.

There is now considerable knowledge concerning neuron death following necrotic insults, and it is believed that the generation of reactive oxygen species (ROS) and oxidative damage play a pivotal role in the neuron death. Prompted by this, we have generated herpes simplex virus‐1 amplicon vectors over‐expressing the genes for the antioxidant enzymes catalase (CAT) or glutathione peroxidase (GPX), both of which catalyze the degradation of hydrogen peroxide. Over‐expression of each of these genes in primary hippocampal or cortical cultures resulted in increased enzymatic activity of the cognate protein. Moreover, each enzyme potently decreased the neurotoxicity induced by kainic acid, glutamate, sodium cyanide and oxygen/glucose deprivation. Finally, these protective effects were accompanied by parallel decreases in hydrogen peroxide accumulation and the extent of lipid peroxidation. These studies not only underline the key role played by ROS in the neurotoxicity of necrotic insults, but also suggest potential gene therapy approaches.

Lymphoid-tissue-specific homing of bone-marrow-derived dendritic cells.

Because of their potent immunoregulatory capacity, dendritic cells (DCs) have been exploited as therapeutic tools to boost immune responses against tumors or pathogens, or dampen autoimmune or allergic responses. Murine bone marrow-derived DCs (BM-DCs) are the closest known equivalent of the blood monocyte-derived DCs that have been used for human therapy. Current imaging methods have proven unable to properly address the migration of injected DCs to small and deep tissues in mice and humans. This study presents the first extensive analysis of BM-DC homing to lymph nodes (and other selected tissues) after intravenous and intraperitoneal inoculation. After intravenous delivery, DCs accumulated in the spleen, and preferentially in the pancreatic and lung-draining lymph nodes. In contrast, DCs injected intraperitoneally were found predominantly in peritoneal lymph nodes (pancreatic in particular), and in omentum-associated lymphoid tissue. This uneven distribution of BM-DCs, independent of the mouse strain and also observed within pancreatic lymph nodes, resulted in the uneven induction of immune response in different lymphoid tissues. These data have important implications for the design of systemic cellular therapy with DCs, and in particular underlie a previously unsuspected potential for specific treatment of diseases such as autoimmune diabetes and pancreatic cancer.

Diagnostic Accuracy of the Urinalysis for Urinary Tract Infection in Infants <3 Months of Age

BACKGROUND: The 2011 American Academy of Pediatrics urinary tract infection (UTI) guideline suggests incorporation of a positive urinalysis (UA) into the definition of UTI. However, concerns linger over UA sensitivity in young infants. Infants with the same pathogenic organism in the blood and urine (bacteremic UTI) have true infections and represent a desirable population for examination of UA sensitivity. METHODS: We collected UA results on a cross-sectional sample of 276 infants <3 months of age with bacteremic UTI from 11 hospital systems. Sensitivity was calculated on infants who had at least a partial UA performed and had ≥50 000 colony-forming units per milliliter from the urine culture. Specificity was determined by using a random sample of infants from the central study site with negative urine cultures. RESULTS: The final sample included 245 infants with bacteremic UTI and 115 infants with negative urine cultures. The sensitivity of leukocyte esterase was 97.6% (95% confidence interval [CI] 94.5%–99.2%) and of pyuria (>3 white blood cells/high-power field) was 96% (95% CI 92.5%–98.1%). Only 1 infant with bacteremic UTI (Group B Streptococcus) and a complete UA had an entirely negative UA. In infants with negative urine cultures, leukocyte esterase specificity was 93.9% (95% CI 87.9 – 97.5) and of pyuria was 91.3% (84.6%–95.6%). CONCLUSIONS: In young infants with bacteremic UTI, UA sensitivity is higher than previous reports in infants with UTI in general. This finding can be explained by spectrum bias or by inclusion of faulty gold standards (contaminants or asymptomatic bacteriuria) in previous studies.

Diagnosis and management of bacteremic urinary tract infection in infants.

OBJECTIVES To report the prevalence of bacteremia by age in a sample of infants<1 year of age with urinary tract infections (UTIs), to compare characteristics of infants with UTIs with and without bacteremia, and to describe treatment courses and 30-day outcomes in infants with UTIs with and without bacteremia. METHODS We used a retrospective cross-sectional design to determine the prevalence of bacteremia in infants with UTIs at our institution. A double cohort design matching for age and gender was used to compare clinical characteristics and outcomes between infants with bacteremic versus nonbacteremic UTIs. RESULTS We identified 1379 UTIs, with blood cultures obtained in 52% of cases. The prevalence of bacteremia was 4.1% (95% confidence interval 3.1%-5.3%) for all UTIs and 8% (95% confidence interval 6.1%-10.2%) for UTIs in which blood culture was obtained. Fifty-five infants with bacteremic UTIs were compared with 110 infants with nonbacteremic UTIs. Except for minor differences in the urinalysis and serum band count, there were no significant differences in clinical presentation between the 2 groups. Bacteremic infants received longer parenteral treatment courses than nonbacteremic infants (mean 6.7 vs 2.4 days, P<.001). Treatment courses in the bacteremic group were variable and predicted by age but not severity of illness. No bacteremic infant had recurrent UTI or bacteremia with the same organism within 30 days of discharge. CONCLUSIONS Treatment was variable but outcomes were excellent in infants with bacteremic UTIs.

Bacteraemic urinary tract infection: Management and outcomes in young infants

Objectives To determine predictors of parenteral antibiotic duration and the association between parenteral treatment duration and relapses in infants <3 months with bacteraemic urinary tract infection (UTI). Design Multicentre retrospective cohort study. Setting Eleven healthcare institutions across the USA. Patients Infants <3 months of age with bacteraemic UTI, defined as the same pathogenic organism isolated from blood and urine. Main outcome measures Duration of parenteral antibiotic therapy, relapsed UTI within 30 days. Results The mean (±SD) duration of parenteral antibiotics for the 251 included infants was 7.8 days (±4 days), with considerable variability between institutions (mean range 5.5–12 days). Independent predictors of the duration of parenteral antibiotic therapy included (coefficient, 95% CI): age (−0.2 days, −0.3 days to −0.08 days, for each week older), year treated (−0.2 days, −0.4 to −0.03 days for each subsequent calendar year), male gender (0.9 days, 0.01 to 1.8 days), a positive repeat blood culture during acute treatment (3.5 days, 1.2–5.9 days) and a non-Escherichia coli organism (2.2 days, 0.8–3.6 days). No infants had a relapsed bacteraemic UTI. Six infants (2.4%) had a relapsed UTI (without bacteraemia). The duration of parenteral antibiotics did not differ between infants with and without a relapse (8.2 vs 7.8 days, p=0.81). Conclusions Parenteral antibiotic treatment duration in young infants with bacteraemic UTI was variable and only minimally explained by measurable patient factors. Relapses were rare and were not associated with treatment duration. Shorter parenteral courses may be appropriate in some infants.

Marked differences in the efficacy of post-insult gene therapy with catalase versus glutathione peroxidase.

It is now recognized that the generation of reactive oxygen species (ROS) following necrotic neurological insults plays a central role in the subsequent neuron death. A key step in ROS detoxification is the conversion of hydrogen peroxide to water and oxygen by either catalase (CAT) or glutathione peroxidase (GPX). We have previously shown that overexpression of CAT or GPX protects cultured neurons against subsequent excitotoxic insults. Because of the unpredictability of most acute neurological insults, gene therapy will most often need to be carried out after rather than in anticipation of an insult. Thus, we have tested whether herpes virus amplicon vectors expressing CAT or GPX still protect cultured hippocampal neurons from oxygen/glucose deprivation if introduced following an insult. CAT-expressing vectors were protective even when introduced 8 h post-insult. In contrast, there was no post-insult time window in which GPX overexpression protected. While CAT requires no cofactor, GPX action requires glutathione as a cofactor. Thus, we speculated that the post-insult decline in glutathione compromises the protective potential of GPX. Supporting this, reversing the post-insult glutathione decline with glutathione supplementation was neuroprotective.

A Clinical Prediction Rule for Rebound Hyperbilirubinemia Following Inpatient Phototherapy.

We describe a model that quantifies the risk of rebound hyperbilirubinemia to help clinicians decide when to discontinue inpatient phototherapy. OBJECTIVES: The American Academy of Pediatrics provides little guidance on when to discontinue phototherapy in newborns treated for hyperbilirubinemia. We sought to develop a prediction rule to estimate the probability of rebound hyperbilirubinemia after inpatient phototherapy. METHODS: Subjects for this retrospective cohort study were infants born in 2012 to 2014 at ≥35 weeks’ gestation at 16 Kaiser Permanente Northern California hospitals who received inpatient phototherapy before age 14 days. We defined rebound as the return of total serum bilirubin (TSB) to phototherapy threshold within 72 hours of phototherapy termination. We used stepwise logistic regression to select predictors of rebound hyperbilirubinemia and devised and validated a prediction score by using split sample validation. RESULTS: Of the 7048 infants treated with inpatient phototherapy, 4.6% had rebound hyperbilirubinemia. Our prediction score consisted of 3 variables: gestational age <38 weeks (adjusted odds ratio [aOR] 4.7; 95% confidence interval [CI], 3.0–7.3), younger age at phototherapy initiation (aOR 0.51 per day; 95% CI, 0.38–0.68), and TSB relative to the treatment threshold at phototherapy termination (aOR 1.5 per mg/dL; 95% CI, 1.4–1.7). The model performed well with an area under the receiver operating characteristic curve of 0.89 (95% CI, 0.86–0.91) in the derivation data set and 0.88 (95% CI, 0.86–0.90) in the validation data set. Approximately 70% of infants had scores <20, which correspond to a <4% probability of rebound hyperbilirubinemia. CONCLUSIONS: The risk of rebound hyperbilirubinemia can be quantified according to an infant’s gestational age, age at phototherapy initiation, and TSB relative to the treatment threshold at phototherapy termination.

Update on Predicting Severe Hyperbilirubinemia and Bilirubin Neurotoxicity Risks in Neonates

Extreme hyperbilirubinemia and kernicterus, though rare, continue to occur despite the adoption of universal screening. Unless they are known to have glucose-6-phosphate dehydrogenase deficiency, infants who currently develop kernicterus in high resource countries are often otherwise healthy newborns discharged from the well-baby nursery. In this review, we highlight risk factors that increase the risk of a newborn ≥35 weeks gestational age developing severe hyperbilirubinemia, as well as the risk factors that increase the hyperbilirubinemic infants risk of kernicterus.