Bedform segregation and locking increase storage of natural and synthetic particles in rivers.

While the ecological significance of hyporheic exchange and fine particle transport in rivers is well established, these processes are generally considered irrelevant to riverbed morphodynamics. We show that coupling between hyporheic exchange, suspended sediment deposition, and sand bedform motion strongly modulates morphodynamics and sorts bed sediments. Hyporheic exchange focuses fine-particle deposition within and below mobile bedforms, which suppresses bed mobility. However, deposited fines are also remobilized by bedform motion, providing a mechanism for segregating coarse and fine particles in the bed. Surprisingly, two distinct end states emerge from the competing interplay of bed stabilization and remobilization: a locked state in which fine particle deposition completely stabilizes the bed, and a dynamic equilibrium in which frequent remobilization sorts the bed and restores mobility. These findings demonstrate the significance of hyporheic exchange to riverbed morphodynamics and clarify how dynamic interactions between coarse and fine particles produce sedimentary patterns commonly found in rivers.

Performance of spectral amplitude coded multiple pulse position modulation with non-uniform energy slots and fading.

Multiple-pulse position modulation (MPPM) is an advanced modulation method for optical wireless communication (OWC), which could provide better performance when channel information is not available. We consider the evaluation of a symbol error rate (SER) expression for MPPM applied within OWC. In the proposed model, MPPM is realized by spectral-amplitude coding (SAC) with non-uniform spectral slot energies. The derived fading channel SER expression is applicable for an arbitrary fading distribution, which may be due to either atmospheric turbulence or transceiver pointing error. A detailed theoretical analysis of the SER is provided and the resulting SER expression is verified by simulation.

Delivery room resuscitation and adverse outcomes among very low birth weight preterm infants.

OBJECTIVE: To evaluate risk factors and impact of delivery room cardiopulmonary resuscitation (DR-CPR) on very low birth weight (VLBW) preterm infants. STUDY DESIGN: A national, population-based, observational study evaluating risk factors and short-term neonatal outcomes associated with DR-CPR among VLBW, extremely preterm infants (EPIs, 24 to 27 weeks' gestation) and very preterm infants (VPI, 28 to 31 weeks' gestation) born in 1995 to 2010. RESULTS: Among 17 564 VLBW infants, 636 (3.6%) required DR-CPR. In the group of 6478 EPI, 412 (6.4%) received DR-CPR compared with 224 of 11 086 infants (2.0%) in the VPI group. EPI who underwent DR-CPR had higher odds ratios (ORs (95% confidence interval)) for mortality compared to EPI not requiring DR-CPR (OR 3.32 (2.58, 4.29)), grades 3 to 4 intraventricular hemorrhage (IVH) (OR 1.59 (1.20, 2.10)) and periventricular leukomalacia (OR 1.81 (1.17, 2.82)). DR-CPR among VPI was associated with higher ORs for mortality (OR 4.99 (3.59, 6.94)), early sepsis (OR 2.07 (1.05, 4.09)), grades 3 to 4 IVH (OR 3.74 (2.55, 5.50)) and grades 3 to 4 retinopathy of prematurity (ROP) (OR 2.53 (1.18, 5.41)) compared to VPI not requiring DR-CPR. Only 11% of infants in the EPI DR-CPR group had favorable outcomes compared with 44% in the VPI DR-CPR group. Significantly higher ORs for mortality, IVH and ROP were found in the VPI compared to the EPI group. CONCLUSION: Preterm VLBW infants requiring DR-CPR were at increased risk of adverse outcomes compared to those not requiring CPR. This effect was more pronounced in the VPI group.

Inhaled hydrofluoalkane-beclomethasone dipropionate in bronchopulmonary dysplasia. A double-blind, randomized, controlled pilot study.

OBJECTIVE: The efficacy of inhaled steroids in spontaneously breathing infants with established bronchopulmonary dysplasia (BPD) is debatable. The inhaled steroid hydrofluoalkane-beclomethasone dipropionate (QVAR) is unique in its small particle size that results in higher lung deposition. Our objective was to determine if inhaled QVAR could decrease respiratory rehospitalizations of infants with established BPD. STUDY DESIGN: Double-blind, randomized placebo-controlled, multicenter pilot study. Preterm infants with moderate-to-severe BPD were randomized to inhaled QVAR 100 µg per dose or placebo twice daily via Aerochamber with face mask. Treatment was administered daily from recruitment at 36 weeks post menstrual age until 3 months post discharge. Analysis was carried out by intention to treat. RESULTS: The QVAR (n=18) and placebo (n=20) groups were comparable in birth and recruitment characteristics. Length of stay (108.5±26.3 vs 108.7±36.0 days) and infants requiring oxygen at discharge (5/17 vs 6/19) or at study end (0/17 vs 2/19) were comparable. Respiratory rehospitalizations/infant (0.1±0.5 vs 0.4±0.6), rehospitalization days (0.5±1.5 vs 4.1±10.3), and post-discharge additive inhaled (0.3±0.9 vs 6.4±21.5 days), systemic (0.7±2.8 vs 1.0±1.4 days) and combined (inhaled/systemic) steroids (1.0±2.9 vs 7.8±25.8 days) tended to be lower in the QVAR compared with the placebo group. Blood pressure, height and weight gain, and urine cortisol/creatinine ratio at study end were comparable between groups. CONCLUSIONS: Our study was unable to detect a significant effect of inhaled QVAR on the respiratory course of established BPD. The study was underpowered. Possible benefits of QVAR could be masked by a tendency toward higher use of additional steroids in the placebo group.

Perinatal factors associated with active intensive treatment at the border of viability: a population-based study.

OBJECTIVE: The aim of this national population-based study was to identify perinatal and neonatal factors associated with active intensive treatment (AIT) of infants born at the periviable period of 22 to 24 weeks of gestation. STUDY DESIGN: Data from the Israel national very low-birth weight infant database on 2207 infants born alive in 1995 to 2010 at gestational age (GA) 22 to 24 weeks were evaluated. AIT was defined as endotracheal intubation in the delivery room or mechanical ventilation in the neonatal intensive care unit. Multivariable logistic regression analyses were used to identify the independent effect of demographic and perinatal factors on AIT for each gestational week. RESULT: Of the 2207 infants born at 22 to 24 weeks GA, 1643 (74.4%) received AIT and 564 (25.6%) received comfort care. AIT increased from 25.5% at 22 weeks to 62.7 and 93.5% at 23 and 24 weeks GA, respectively, reflecting a 4.66 (95% confidence interval (CI) 3.32 to 6.54)- and 29.8 (95% CI 19.9 to 44.6)-fold odds for AIT at 23 and 24 weeks GA, respectively, compared with 22-week GA infants. Perinatal treatments associated with AIT included maternal tocolytic therapy (odds ratio (OR) 1.51, 95% CI 1.04 to 2.20), prenatal steroid therapy, both partial (OR 3.30, 95% CI 2.14 to 5.10) and complete (OR 3.17, 95% CI 1.91 to 5.26) and cesarean delivery (OR 2.68, 95% CI 1.88 to 3.83). Each unit increase in birth weight z-score was associated with an OR of 1.58 (95% CI 1.30 to 1.92) for AIT. At 22 weeks GA, maternal tocolytic treatment was associated with higher odds of AIT. In the 23 and 24-week GA infants, maternal infertility treatment, antenatal steroids, cesarean delivery and higher-birth weight z-scores were significantly associated with AIT. Among 23-week GA infants, AIT decreased significantly in the period 2006 to 2010 compared with 1995 to 2000 (OR 0.51, 95% CI 0.34 to 0.77). CONCLUSION: An active approach in obstetric management of pregnancies appears to impact the neonatologists' decision to undertake AIT treatment in infants born at the border of viability. The higher odds for AIT associated with obstetric interventions might contribute to the reported beneficial effect of antenatal steroids and cesarean delivery on the survival of infants born at the border of viability.

Infiltration mechanism controls nitrification and denitrification processes under dairy waste lagoon.

Earthen waste lagoons are commonly used to store liquid wastes from concentrated animal feeding operations. The fate of ammonium (NH) and nitrate (NO) was studied in the vadose zone below earthen-clay dairy farm waste lagoons using three independent vadose zone monitoring systems. The vadose zone was monitored from 0.5 to 30 m below land surface through direct sampling of the sediment porewater and continuous measurement of the sediment profile's water content variations. Four years of monitoring revealed that wastewater infiltration from the lagoon is controlled by two mechanisms: slow (mm d), constant infiltration from the lagoon bed; and rapid (m h) infiltration of wastewater and rainwater via preferential flow in desiccation cracks formed in the unsaturated clay sediment surrounding the lagoon banks. The preferential flow mechanism is active mainly during wastewater-level fluctuations and intensive rain events. The vadose zone below the waste sources remained unsaturated throughout the monitoring period, and all infiltrating NH was oxidized in the upper 0.5 m. The NH oxidation (nitrification) was coupled with NO reduction (denitrification) and depended on the sediment water content, which was controlled by the infiltration mechanism. Coupled nitrification-denitrification (CND) resulted in 90 to 100% reduction in the total nitrogen mass in the vadose zone, with higher removal under high water content (∼0.55 m m). Mass balance of nitrogen and isotopic composition of NO indicated that CND, rather than cation exchange capacity, is the key factor regulating nitrogen's fate in the vadose zone underlying earthen waste lagoons.

Novel structural elements within the nonproteolytic clostridium botulinum type F toxin gene cluster.

We sequenced for the first time the complete neurotoxin gene cluster of a nonproteolytic Clostridium botulinum type F. The neurotoxin gene cluster contained a novel gene arrangement that, compared to other C. botulinum neurotoxin gene clusters, lacked the regulatory botR gene and contained an intergenic is element between its orfX2 and orfX3 genes.

Iron supplementation for preterm infants receiving restrictive red blood cell transfusions: reassessment of practice safety.

OBJECTIVE: To reassess iron supplementation practice safety in very low birth weight (VLBW) preterm infants receiving restrictive red blood cell transfusions during initial hospitalization. STUDY DESIGN: Iron status, including hemoglobin (Hb), serum iron, ferritin, and soluble transferrin receptor (sTfR) levels and reticulocyte count of transfused (n=236) and non-transfused (n=166) preterm infants at ≤24 h and 2, 4 and 8 weeks were recorded. As per protocol, a restrictive blood transfusion policy and supplementation of 5 mg kg(-1) per day of iron polymaltose complex from 4 weeks and 25 mg(-1) per day of vitamin E from 2 weeks were imposed for all infants. Normative reference cord-blood ferritin value of preterm infants was used for comparison. Vitamin E levels and incidence of morbidities associated with prematurity were recorded. RESULT: At ≤24 h, the characteristics and iron status of both groups were similar. At 2, 4 and 8 weeks, the transfused group had significantly higher Hb, iron and ferritin levels; sTfR levels were lower at 4 and 8 weeks (all indices, P<0.05). At 8 weeks, the median ferritin levels of our transfused group were lower than that of normative reference cord-blood value (115 (50th percentile) vs 79 (43 to 107) µg l(-1), respectively). Vitamin E levels and the incidence of morbidities associated with prematurity of the transfused and non-transfused groups were not different (both indices, P>0.18). CONCLUSION: Adding iron supplementation to preterm infants receiving restrictive blood transfusions has shown to be a judicious and safe practice in terms of iron status for VLBW preterm infants.

Meconium periorchitis: intrauterine diagnosis and neonatal outcome: case reports and review of the literature.

Meconium periorchitis (MP) is a rare disorder caused by fetal meconium peritonitis with subsequent spillage of meconium into the scrotal sac. The condition is seldom diagnosed correctly during fetal life and the ultrasonographic diagnoses reported vary from no diagnosis to hematoma or hydrocele. It is usually diagnosed clinically during the first year of life when a scrotal mass is an incidental finding. Here, we describe two cases of MP that were diagnosed during routine intrauterine ultrasound examination for fetal growth assessment, and confirmed after birth. One infant underwent a surgical excision of the scrotal mass, confirming the histological diagnosis of meconium periorchitis. The other was managed conservatively. Neither had cystic fibrosis. Thus, we believe that a diagnosis of MP should be considered when prenatal ultrasonographic findings are suspicious for the problem. The awareness of the ultrasonographer and the neonatologist are important for immediate postnatal management, as congenital scrotal masses may have other etiologies.

Antenatal mitochondrial disease caused by mitochondrial ribosomal protein (MRPS22) mutation.

Three patients born to the same set of consanguineous parents presented with antenatal skin oedema, hypotonia, cardiomyopathy and tubulopathy. The enzymatic activities of multiple mitochondrial respiratory chain complexes were reduced in muscle. Marked reduction of 12s rRNA, the core of the mitochondrial small ribosomal subunit, was found in fibroblasts. Homozygosity mapping led to the identification of a mutation in the MRPS22 gene, which encodes a mitochondrial ribosomal protein. Transfection of the patient cells with wild-type MRPS22 cDNA increased the 12s rRNA content and normalised the enzymatic activities. Quantification of mitochondrial transcripts is advisable in patients with multiple defects of the mitochondrial respiratory chain.

Serum amyloid A: an early and accurate marker of neonatal early-onset sepsis.

OBJECTIVES: To evaluate the accuracy of serum amyloid A (SAA), an acute phase protein in the detection of neonatal early-onset sepsis, by means of a fast automated SAA kit. STUDY DESIGN: Full-term infants <72 h of age, who had risk factors and/or were suspected of having sepsis, were eligible for study. The levels of SAA were taken at 0, 24 and 48 h post sepsis evaluation. Thirty matched infants served as a control group for comparing SAA concentrations. RESULTS: Of 104 infants eligible for entry to the study, 23 had sepsis and 81 had not sepsis. The SAA levels of the septic group were significantly higher than those of the nonseptic group at 0, 24 and 48 h (P<0.01 for all time points). In comparison with C-reactive protein (CRP), SAA levels rose earlier and in a sharper manner, had higher levels and returned faster to normal values in infants with early onset sepsis. At 0 h post-sepsis evaluation, serum SAA had an overall better diagnostic accuracy for predicting early onset sepsis than CRP (sensitivity (96 vs 30%), specificity (95 vs 98%), positive predictive value (85 vs 78%), negative predictive value (99 vs 83%), positive likelihood ratio (19 vs 12), and negative likelihood ratio (0.05 vs 0.71). CONCLUSIONS: SSA is advocated as an inflammatory marker of neonatal early-onset sepsis.

Assisted exercise and bone strength in preterm infants.

Studies have previously demonstrated that brief (4 weeks) passive range-of-motion exercise is beneficial for bone development in very low birth weight (VLBW) preterm infants. However, the optimal duration of exercise for bone development in preterm infants is yet unknown. The aim of the present study was to examine the effect of 8 weeks of assisted exercise on bone strength and metabolism in VLBW premature infants. Sixteen infants (mean +/- standard error of the mean birth weight 1,009 +/- 55 g and gestational age 27.3 +/- 0.3 weeks) were randomly assigned into exercise (n = 8) and control (n = 8) groups. The intervention started at the first week of life and involved 8 weeks of daily passive extension and flexion range-of-motion exercise of the upper and lower extremities. Biochemical markers of bone turnover were measured at enrollment and after 8 weeks. Bone strength was measured weekly by quantitative ultrasound measurement of tibial bone speed of sound (SOS). Bone SOS decreased significantly in the control group (-108.1 +/- 33.7 m/second, P < 0.0001) during the study period, while remaining stable in the exercise group (11.3 +/- 22.8 m/second). The main beneficial effect of exercise occurred in the first 4 weeks of the intervention. There were no significant differences in the bone turnover marker changes between the groups. There is a significant postnatal decrease in bone SOS in VLBW preterm infants. Eight weeks of assisted range-of-motion exercise attenuates the decrease in bone strength and may decrease the risk of osteopenia in premature infants.

Neonatologists are using much less dexamethasone.

Two historical cohorts (1993-1994 and 2001) of preterm infants ventilated for respiratory distress syndrome were compared. Dexamethasone administration fell from 22% to 6%. Chronic lung disease in survivors rose slightly from 13% to 17%, and mortality fell from 21% to 15% (other causes). The effect of restriction of dexamethasone use on chronic lung disease and mortality remains to be seen.

Glu274Lys/Gly309Arg mutation of the tissue-nonspecific alkaline phosphatase gene in neonatal hypophosphatasia associated with convulsions.

We describe a patient diagnosed with lethal perinatal hypophosphatasia with a unique clinical presentation of convulsions that responded to vitamin B6. Genomic DNA sequence analysis of the tissue-nonspecific alkaline phosphatase (TNSALP) gene revealed two missense mutations: a G-to-A transition resulting in a Glu to Lys at codon 274 (E274K), and a G-to-C transversion resulting in a Gly to Arg at codon 309 (G309R). The first mutation was maternally transmitted and was previously characterized as a moderate one, whereas the latter was paternally transmitted and has not been previously reported. Phenotype/genotype correlation indicates that G309R is a deleterious mutation that can lead to seizures and a lethal outcome, as was demonstrated in our patient.

Preterm labour at 34--36 weeks of gestation: should it be arrested?

Currently, preterm labour is treated with tocolytic agents and prenatal steroids until the 34th week of gestation only. Our objective in this study was to assess this practice. Seven-year records of all preterm infants born in our institution at 34--36 weeks of gestation, were evaluated retrospectively. All babies, born in singleton well-dated pregnancies, without maternal, medical or obstetric complications, and by normal vaginal delivery, were included. Their length of hospital stay and perinatal complications were compared across gestational age groups of 34, 35 and 36 weeks. Of the 207 babies included, statistically significant reductions in the rates of respiratory distress syndrome (15.0% vs. 3.2%), nosocomial sepsis (5.0% vs. 0%) and apnoea of prematurity (11.7% vs. 2.2%), and consequently, in length of hospital stay (16 +/- 2.7 vs. 4 +/- 0.3 days) occurred between 34 and 36 weeks of gestation. The severity of respiratory distress syndrome also declined significantly. The changes were most noticeable after 35 weeks of gestation, and it was concluded that neonatal complications are still prevalent at 34 and 35 weeks. Therefore, we propose that labour should not be induced at 34 and 35 weeks of gestation and that tocolytic agents and maternal prenatal steroids may be considered in preterm labour during this period.

Measurements of bone turnover markers in premature infants.

We determined the levels of circulating bone turnover markers in preterm infants during the first weeks of life. Twenty premature infants (mean gestational age 27+/-2.2 weeks, mean birth weight 894+/-231 g) hospitalized in the neonatal intensive care unit (NICU) at the Meir General Hospital, Israel, participated in the study. Measurements of bone turnover markers were performed at birth, and every week thereafter for an average follow-up of 11.2+/-0.7 weeks. Bone osteoblastic activity was assessed by measurements of circulating osteocalcin, bone-specific alkaline phosphatase (BSAP) and the C-terminal procollagen peptide (PICP) levels. Bone resorption was assessed by measurements of serum levels of the carboxy-terminal cross-links telopeptide of type I collagen (ICTP). All three markers of osteoblastic activity increased markedly and significantly during the first three weeks of life, and then continued to increase gradually until week 10 (p<0.01). Circulating ICTP levels increased in the first week of life and then decreased gradually throughout the follow-up (p<0.01). The study participants were divided into premature infants born at extremely low birth weight (ELBW: <1000 g, n=12) and very low birth weight (VLBW: 1000-1250 g, n=8). Osteocalcin (in weeks 2-5 of life), PICP (weeks 3-5), and ICTP levels (weeks 2-3) were significantly higher in VLBW preterms. These results suggest increased bone formation in premature infants in the first three months of life. The increased bone turnover in VLBW compared to ELBW premature infants may be the result of a generally higher morbidity in ELBW preterm infants in early stages of life.

Botulinum toxin as a biological weapon: medical and public health management.

OBJECTIVE: The Working Group on Civilian Biodefense has developed consensus-based recommendations for measures to be taken by medical and public health professionals if botulinum toxin is used as a biological weapon against a civilian population. PARTICIPANTS: The working group included 23 representatives from academic, government, and private institutions with expertise in public health, emergency management, and clinical medicine. EVIDENCE: The primary authors (S.S.A. and R.S.) searched OLDMEDLINE and MEDLINE (1960-March 1999) and their professional collections for literature concerning use of botulinum toxin as a bioweapon. The literature was reviewed, and opinions were sought from the working group and other experts on diagnosis and management of botulism. Additional MEDLINE searches were conducted through April 2000 during the review and revisions of the consensus statement. CONSENSUS PROCESS: The first draft of the working group's consensus statement was a synthesis of information obtained in the formal evidence-gathering process. The working group convened to review the first draft in May 1999. Working group members reviewed subsequent drafts and suggested additional revisions. The final statement incorporates all relevant evidence obtained in the literature search in conjunction with final consensus recommendations supported by all working group members. CONCLUSIONS: An aerosolized or foodborne botulinum toxin weapon would cause acute symmetric, descending flaccid paralysis with prominent bulbar palsies such as diplopia, dysarthria, dysphonia, and dysphagia that would typically present 12 to 72 hours after exposure. Effective response to a deliberate release of botulinum toxin will depend on timely clinical diagnosis, case reporting, and epidemiological investigation. Persons potentially exposed to botulinum toxin should be closely observed, and those with signs of botulism require prompt treatment with antitoxin and supportive care that may include assisted ventilation for weeks or months. Treatment with antitoxin should not be delayed for microbiological testing.

Dichloroacetate treatment for severe refractory metabolic acidosis during neonatal sepsis.

We describe a preterm neonate with documented group B Streptococcus sepsis and associated metabolic acidosis whose lactic acidemia was refractory to conventional sodium bicarbonate therapy but responded well to dichloroacetate treatment.