Urinary tract infections in very low birthweight infants: A two-center analysis of microbiology, imaging and heart rate characteristics.

BACKGROUND: Increased understanding of characteristics of urinary tract infection (UTI) among very low birthweight infants (VLBW) might lead to improvement in detection and treatment. Continuous monitoring for abnormal heart rate characteristics (HRC) could provide early warning of UTIs. OBJECTIVE: Describe the characteristics of UTI, including HRC, in VLBW infants. METHODS: We reviewed records of VLBW infants admitted from 2005-2010 at two academic centers participating in a randomized clinical trial of HRC monitoring. Results of all urine cultures, renal ultrasounds (RUS), and voiding cystourethrograms (VCUG) were assessed. Change in the HRC index was analyzed before and after UTI. RESULTS: Of 823 VLBW infants (27.7±2.9 weeks GA, 53% male), 378 had > / = 1 urine culture obtained. A UTI (≥10,000 CFU and >five days of antibiotics) was diagnosed in 80 infants, (10% prevalence, mean GA 25.8±2.0 weeks, 76% male). Prophylactic antibiotics were administered to 29 (36%) infants after UTI, of whom four (14%) had another UTI. Recurrent UTI also occurred in 7/51 (14%) of infants not on uroprophylaxis after their first UTI. RUS was performed after UTI in 78%, and hydronephrosis and other major anomalies were found in 19%. A VCUG was performed in 48% of infants and 18% demonstrated vesicoureteral reflux (VUR). The mean HRC rose and fell significantly in the two days before and after diagnosis of UTI. CONCLUSIONS: UTI was diagnosed in 10% of VLBW infants, and the HRC index increased prior to diagnosis, suggesting that continuous HRC monitoring in the NICU might allow earlier diagnosis and treatment of UTI.

Chondrogenic potential of IL-10 in mechanically injured cartilage and cellularized collagen ACI grafts.

OBJECTIVE: The application of adjunctive mediators in Autologous chondrocyte implantation (ACI) techniques might be useful for improving the dedifferentiated chondrocyte phenotype, to support neocartilage formation and inhibit post-traumatic cartilage destruction. In this study we examined if (a) interleukin 10 treatment can cause chondrogenic phenotype stabilization and matrix preservation in mechanically injured cartilage and if (b) IL-10 can promote chondrogenesis in a clinically applied collagen scaffold for ACI treatment. MATERIALS AND METHODS: For (a) bovine articular cartilage was harvested, subjected to an axial unconfined injury and treated with bovine IL-10 (1-10,000 pg/ng/ml). For (b) a post-operatively remaining ACI graft was treated with human IL-10. Expression levels of type I/II/X collagen, SOX9 and aggrecan were measured by qPCR (a,b). After 3 weeks cell death was analyzed (nuclear blebbing and TUNEL assay) and matrix composition was determined by GAG measurements and immunohistochemistry (aggrecan, type I/II collagen, hyaluronic acid). STATISTICS: One way ANOVA analysis with Bonferroni's correction. RESULTS: (a) IL-10 stabilized the chondrogenic phenotype after injurious compression and preserved matrix integrity. This was indicated by elevated expression of chondrogenic markers COL2A1, ACAN, SOX9, while COL1A1 and COL10A1 were reduced. An increased GAG content paralleled this and histological staining of type 2 collagen, aggrecan and toluidine blue were enhanced after 3 weeks. (b) IL-10 [100 pg/ml] improved the chondrogenic differentiation of human chondrocytes, which was accompanied by cartilaginous matrix formation after 3 weeks of incubation. CONCLUSION: Interleukin-10 is a versatile adjuvant candidate to control the post-injurious environment in cartilage defects and promote chondrogenesis in ACI grafts.

Oral colostrum priming shortens hospitalization without changing the immunomicrobial milieu.

OBJECTIVE: Oral colostrum priming (OCP) after birth in preterm infants is associated with improved weight gain and modification of the oral immunomicrobial environment. We hypothesized that OCP would modify salivary immune peptides and the oral microbiota in preterm infants. STUDY DESIGN: We conducted a prospective, randomized clinical trial to determine the effects of OCP on salivary immune peptide representation in preterm infants (<32 weeks completed gestation at birth). Saliva samples were collected before and after OCP. Salivary immune peptide representation was determined via mass spectroscopy. Oral microbiota representation was determined via sequencing of the 16S rRNA gene. RESULTS: Neonates who received OCP (n=48) had a 16-day reduction in the median length of hospitalization as compared with infants who did not receive OCP (n=51). No differences in salivary immune peptide sequence representation before OCP between groups were found. Longitudinal changes in peptides were detected (lysozyme C, immunoglobulin A, lactoferrin) but were limited to a single peptide difference (α-defensin 1) between primed and unprimed infants after OCP. We found no difference in microbial diversity between treatment groups at any time point, but diversity decreased significantly over time in both groups. OCP treatment marginally modified oral taxa with a decline in abundance of Streptococci in the OCP group at 30 days of life. CONCLUSIONS: OCP had neither an effect on the salivary peptides we examined nor on overall oral bacterial diversity and composition. Infants who received OCP had a reduced length of hospitalization and warrants further investigation.

Abnormal heart rate characteristics before clinical diagnosis of necrotizing enterocolitis.

OBJECTIVE: Earlier diagnosis and treatment of necrotizing enterocolitis (NEC) in preterm infants, before clinical deterioration, might improve outcomes. A monitor that measures abnormal heart rate characteristics (HRC) of decreased variability and transient decelerations was developed as an early warning system for sepsis. As NEC shares pathophysiologic features with sepsis, we tested the hypothesis that abnormal HRC occur before clinical diagnosis of NEC. STUDY DESIGN: Retrospective review of Bells stage II to III NEC cases among infants <34 weeks gestation enrolled in a prospective randomized clinical trial of HRC monitoring at three neonatal intensive care units. RESULT: Of 97 infants with NEC and HRC data, 33 underwent surgical intervention within 1 week of diagnosis. The baseline HRC index from 1 to 3 days before diagnosis was higher in patients who developed surgical vs medical NEC (2.06±1.98 vs 1.22±1.10, P=0.009). The HRC index increased significantly 16 h before the clinical diagnosis of surgical NEC and 6 h before medical NEC. At the time of clinical diagnosis, the HRC index was higher in patients with surgical vs medical NEC (3.3±2.2 vs 1.9±1.7, P<0.001). CONCLUSION: Abnormal HRC occur before clinical diagnosis of NEC, suggesting that continuous HRC monitoring may facilitate earlier detection and treatment.

Micro-imaging of transient guest profiles in nanochannels.

Zeolites of type ferrierite are exploited as a host system for monitoring the evolution of guest concentration (methanol) in nanoporous host materials upon adsorption. Additional transport resistances at the crystal surface have been removed so that uptake is exclusively controlled by the diffusion resistance of the pore space. Since the crystal shape deviates from a simple parallelepiped, the primary imaging data do not immediately reflect true local concentrations. A simple algorithm is developed which overcomes this complication. The determined transient concentration profiles ideally comply with the requirements for the application of the Boltzmann-Matano integration method for determining diffusivities. The resulting diffusivities (along the direction of the "10-ring channels") are found to exceed those along the 8-ring channels by three orders of magnitude.

A silver-alginate-coated dressing to reduce peripherally inserted central catheter (PICC) infections in NICU patients: a pilot randomized controlled trial.

OBJECTIVE: Our aim was to evaluate the safety of a silver-alginate-containing dressing to reduce peripherally inserted central catheter (PICC) infections in neonatal intensive care unit (NICU) patients. STUDY DESIGN: Patients were randomized 3:1 to receive a patch containing silver, alginate and maltodextrin or standard of care. Patches were placed under the regular transparent retention dressing at the PICC exit site at insertion and were replaced with every dressing change at least every 2 weeks until PICC discontinuation. All study infants were monitored for adverse skin reactions. RESULT: A total of 100 infants were followed up for 1922 person-days, including 75 subjects with 89 PICCs who received the patch. The median birth weight (1330 g) and median gestational age (30 weeks) was lower in the patch group when compared with the controls (P=0.001 and 0.005, respectively). Study patients received the patch with their PICC at a median age of 5 days; the patch stayed in place for a median of 13 days. We noted no adverse skin reactions and found no evidence that the patch alters the microbiology of PICC-associated infections. CONCLUSION: This pilot trial suggests that silver-alginate-coated dressings are skin safe and their inclusion in future trials aimed at reduction of PICC-associated bloodstream infections in the NICU should be considered.

Fluconazole prophylaxis for prevention of invasive fungal infections in targeted highest risk preterm infants limits drug exposure.

OBJECTIVE: Previous reports suggest a benefit of fluconazole prophylaxis in extremely low birth weight (ELBW) infants <1000 g. Our aim was to evaluate if limiting fluconazole prophylaxis to targeted highest risk infants effectively prevents invasive fungal infections, has no undesired side effects and limits unnecessary drug exposure. STUDY DESIGN: This nonrandomized retrospective pre-post intervention study compared two groups of infants: (1) Infants <26 weeks gestation and/or <750 g birth weight, requiring central vascular access and admitted to the Monroe Carell Jr Children's Hospital at Vanderbilt neonatal intensive care unit (NICU) prior to 5 days of age, who received fluconazole prophylaxis and (2) a matched control group from the year prior to prophylaxis. This target population was selected for fluconazole prophylaxis based on prior infection control data from our institution and a number needed to treat of <15 to prevent one episode of fungemia. Following implementation and integration through the institution's computerized physician order entry (CPOE) system, provider adherence to the protocol was assessed during the prophylaxis period. RESULT: A total of 86 patients were included in the study, 44 in the no-prophylaxis group and 42 in the prophylaxis group. In the targeted prophylaxis group, no invasive fungal infections were observed as compared to nine infants with invasive infections in the no-prophylaxis group (P=0.004). No significant adverse effects were recorded. Targeting the highest risk infants reduced the number of infants <1000 g requiring prophylaxis from 80 to 42 (48% reduction) with no preventable infection missed. Provider compliance was 91% following implementation of this protocol through the CPOE system using a standardized order set. CONCLUSION: Targeting the highest risk infants for fluconazole prophylaxis through CPOE can effectively prevent invasive fungal infections and limit drug exposure with no unwanted side effects.

Endogenous group B streptococcal endophthalmitis in a preterm infant.

Endogenous endophthalmitis is a rare complication of bacteremia. Proper intervention is critical, as the majority of affected patients lose vision in the infected eye. Treatment options include systemic antibiotics, intravitreous antibiotics and vitrectomy. We report a case of endogenous endophthalmitis presenting as leukocoria in a premature neonate with group B streptococcal meningitis.

The role of mesopores in intracrystalline transport in USY zeolite: PFG NMR diffusion study on various length scales.

PFG NMR has been applied to study intracrystalline diffusion in USY zeolite as well as in the parent ammonium-ion exchanged zeolite Y used to produce the USY by zeolite steaming. The diffusion studies have been performed for a broad range of molecular displacements and with two different types of probe molecules (n-octane and 1,3,5-triisopropylbenzene) having critical molecular diameters smaller and larger than the openings of the zeolite micropores. Our experimental data unambiguously show that, in contrast to what is usually assumed in the literature, the intracrystalline mesopores do not significantly affect intracrystalline diffusion in USY. This result indicates that the intracrystalline mesopores of USY zeolite do not form a connected network, which would allow diffusion through crystals only via mesopores.

Pulsed-field gradient nuclear magnetic resonance study of transport properties of fluid catalytic cracking catalysts.

Pulsed-field gradient nuclear magnetic resonance (PFG NMR) has been applied to study molecular diffusion in industrial fluid catalytic cracking (FCC) catalysts and in USY zeolite for a broad range of molecular displacements and temperatures. The results of this study have been used to elucidate the relevance of molecular transport on various displacements for the rate of molecular exchange between catalyst particles and their surroundings. It turned out that this rate, which may determine the overall rate and selectivity of FCC process, is primarily related to the diffusion mode associated with displacements larger than the size of zeolite crystals located in the particles but smaller than the size of the particles. This conclusion has been confirmed by comparative studies of the catalytic performance of different FCC catalysts.

Genetic and structural determinants of virus neutralizing antibodies.

Neutralizing antibodies (Abs) are the principal protective mechanism against disease caused by reinfection with viruses. Ab-mediated neutralization of viruses is a complex process comprising multiple mechanisms. Every structural aspect of Abs is potentially capable of modulating the level of neutralizing activity or the mechanisms of neutralization. The focus of our laboratory is to understand the genetic and structural basis of Ab-mediated neutralization of human viral pathogens. We demonstrated the unexpected finding that virus antigen-binding fragments of Abs (Fabs) mediate potent virus neutralizing effects in vivo. This work has led to a broad investigation of the importance of the genetics, chemistry, and structure of the combining site to the neutralizing activity of antiviral Abs. Ongoing work in our laboratory reveals that effect or functions specified by the Ab isotype such as polymer formation, interactions with complement, interactions with Fc receptors, and the ability to transcytose mucosal epithelia, also modulate the mechanism and level of neutralizing effects mediated by antiviral Abs.

In situ IR, NMR, EPR, and UV/Vis Spectroscopy: Tools for New Insight into the Mechanisms of Heterogeneous Catalysis.

The development of new solid catalysts for use in industrial chemistry has hitherto been based to a large extent upon the empirical testing of a wide range of different materials. In only a few exceptional cases has success been achieved in understanding the overall, usually very complex mechanism of the chemical reaction through the elucidation of individual intermediate aspects of a heterogeneously catalyzed reaction. With the modern approach of combinatorial catalysis it is now possible to prepare and test much more rapidly a wide range of different materials within a short time and thus find suitable catalysts or optimize their chemical composition. Our understanding of the mechanisms of reactions catalyzed by these materials must be developed, however, by spectroscopic investigations on working catalysts under conditions that are as close as possible to practice (temperature, partial pressures of the reactants, space velocity). This demands the development and the application of new techniques of in situ spectroscopy. This review will show how this objective is being achieved. By the term in situ (Lat.: in the original position) is meant the investigation of the chemical reactions which are taking place as well as the changes in the working catalysts directly in the spectrometer.

Recurrent Achromobacter xylosoxidans bacteremia associated with persistent lymph node infection in a patient with hyper-immunoglobulin M syndrome.

Achromobacter xylosoxidans (formerly Alcaligenes xylosoxidans) is a rare but important cause of bacteremia in immunocompromised patients, and strains are usually multiply resistant to antimicrobial therapy. We report an immunocompromised patient with hyper-immunoglobulin M syndrome who suffered from 14 documented episodes of A. xylosoxidans bacteremia. Each episode was treated and resulted in rapid clinical improvement, with blood cultures testing negative for bacteria. Between episodes, A. xylosoxidans was isolated from an excised right axillary lymph node, whereas the culture of the central venous catheter, removed at the same time, was negative. Multiple cultures from sputum, stool, and urine samples, as well as from gastrointestinal biopsies or environmental sources, were negative. Results from antibiotic sensitivity testing and pulsed-field gel electrophoresis suggested that a single strain of A. xylosoxidans caused the recurrent bacteremias in this patient; this strain originated from persistently infected lymph nodes. Lymphoid hyperplasia is a prominent characteristic of hyper-IgM syndrome and may serve as a source of bacteremia with low-pathogenicity organisms.

Pilot study assessing TNF gene polymorphism as a prognostic marker for disease progression in neonates with sepsis.

In adult postoperative intensive care patients, the biallelic Ncol polymorphism within the tumor necrosis factor (TNF) locus has been shown to be a genomic marker for individuals with increased TNF-alpha response and poor prognosis in severe sepsis. We characterized the genomic distribution and allele frequency of the Ncol polymorphism in 23 preterm and term neonatal intensive care unit (NICU) patients with culture-proven sepsis and compared it with clinical and laboratory characteristics to assess its prognostic value for disease progression. Genotype analysis demonstrated the following absolute (relative) frequencies: 7 (0.31) infants were homozygous for the allele TNFB2 (Group A). 12 (0.52) infants were heterozygous (TNFB1/TNFB2) and four (0.17) infants homozygous for the allele TNFB1 (Group B). There was no significant difference compared to adult intensive care patients with severe sepsis (p = 0.31). The median gestational age of all infants (13 female and ten male) as well as for either group was 28 weeks (range 23-37) with a median birth weight of 845 g (range 560-2,720). The study population included a total of 16 very low birth weight (VLBW) infants, four in Group A and 12 in Group B. However, there was no significant difference for gestational age and birth weight in both groups (p = 0.82 and 0.71, respectively). Laboratory parameters as maximum and minimum leukocyte and thrombocyte counts, maximum immature to total neutrophil ratios (ITR), maximum C-reactive protein (CRP) levels, days of CRP levels > 5 mg/l and total days of antibiotic treatment, were not statistically different in both groups. In total, three infants (13%) died in consequence of their underlying disease. Two infants belonged to Group A and one to Group B. The statistical analysis of outcome variables (mortality, neurological impairment, failure to thrive) was not possible, because the study population was small and the reasons for poor outcome and death in these high-risk patients had to be considered multifactorial. In conclusion, in this pilot study the biallelic Ncol polymorphism within the TNF locus was not a prognostic marker for disease progression in high-risk NICU-admitted term and preterm infants with culture-proven sepsis. In order to detect differences in outcome similar to adult postsurgical patients with severe sepsis, an unfeasibly high number of NICU patients with culture-proven sepsis would need to be included for a similar study.

Candida infection in very low birth-weight infants: outcome and nephrotoxicity of treatment with liposomal amphotericin B (AmBisome).

Systemic fungal infection occurs in 2 to 4.5% of very low birth-weight (VLBW) infants (< 1,500 g) and may be fatal in 25 to 54%. Candida sp. is the major pathogen and amphotericin B the treatment of choice. To reduce side effects and optimize drug action, a formulation of amphotericin B encapsulated in liposomes (AmBisome) has been introduced. Data on 21 VLBW infants who received a full course of AmBisome was collected and its toxic effects with emphasis on nephrotoxicity and hypokalemia assessed. The median gestational age was 25 weeks (range 23-31) with a median birth-weight of 730 g (range 450-1,370). Antifungal therapy was started at a median age of 13 days (range 1-49). The median dose given was 2.6 mg/kg/day (range 1-5), and the median duration of therapy was 28 days (range 11-79), corresponding to a median cumulative dose of 71 mg/kg (range 12-271). Hypokalemia (< 3.0 mmol/l) was observed in 30% before, and 15% during AmBisome treatment. Twenty-one days after the termination of therapy, hypokalemia was not present in any patient. Median maximum daily potassium supplementation did not exceed doses usually recommended for VLBW infants. The median of the maximum creatinine levels before treatment was 121 mumol/l (range 71-221) and fell to 68 mumol/l (range 31-171) during treatment and 46 mumol/l (range 26-62) 21 days after the termination of therapy. All patients treated with AmBisome eradicated fungi and recovered clinically. AmBisome showed no certain nephrotoxicity in VLBW infants in this study.

Identification and characterization of Helicobacter pylori phospholipase C activity.

We analyzed 11 H. pylori isolates from humans using the artificial chromogenic substrate paranitrophenylphosphorylcholine to detect phospholipase C (PLC) activity. The range of PLC in sonicates was 8.8-92.3 (Mean 56.9 +/- 6.5) nmol of substrate hydrolysed min-1 mg-1 protein; the amount of activity was not associated with urease or cytotoxin levels. Addition of sorbitol or glycerol enhanced PLC activity of H. pylori sonicate and purified PLC from C. perfringens (PLC1) but not purified PLC from B. cereus (PLC3). H. pylori sonicates had little acid phosphatase and no detectable alkaline phosphatase activity, and H. pylori PLC showed markedly different biochemical characteristics from either phosphatase. In total, these studies indicate that activity measured in H. pylori sonicate by PLC assay is due to PLC and not phosphatase activity. The temperature optimum for PLC activity of H. pylori sonicate was 56 degrees C and for PLC 1 was 65 degrees C. For H. pylori PLC and PLC1, optimal activity occurred at pH 8. Despite multiple similarities between H. pylori PLC and PLC1, known PLC inhibitors show different interactions with each enzyme. Although PLC activity is present in many subcellular constituents of H. pylori, including culture supernatants and water extracts, highest specific activity is associated with a membrane-enriched fraction.

Characterization of sodium cations in dehydrated faujasites and zeolite EMT by 23Na DOR, 2D nutation, and MAS NMR.

Sodium cations localized at crystallographically distinct cation sites in dehydrated zeolites were characterized using 23Na double rotation, two-dimensional nutation, and magic-angle-spinning nuclear magnetic resonance spectroscopy. The new DOR NMR technique has been applied at different magnetic field strengths to determine the quadrupole parameters of the overlapping quadrupole patterns. In the NMR spectra of dehydrated NaY and NaEMT two signals of sodium cations were identified, a low-field gaussian line at -12 +/- 1 ppm and a high-field quadrupole pattern, with an isotropic chemical shift of -8 +/- 1 ppm and a quadrupole coupling constant of about 4 MHz. By comparison of the 23Na MAS NMR intensities of these signals with the population of the cation sites determined by XRD and by calculation of the electric field gradients, the former signal was attributed to sodium cations at the sites SI and the latter one to sodium cations at the sites SI' as well as SII in faujasite and zeolite EMT. This assignment has further been confirmed by 23Na MAS NMR studies of dehydrated HNaY and BaNaY zeolites.