International Variation in the Management of Patent Ductus Arteriosus and Its Association with Infant Outcomes: A Survey and Linked Cohort Study.

OBJECTIVE: To assess whether treating patients with a presymptomatic patent ductus arteriosus (PDA), based on early routine echocardiography, performed regardless of clinical signs, improved outcomes. STUDY DESIGN: This multicenter, survey-linked retrospective cohort study used an institutional-level questionnaire and individual patient-level data and included infants of <29 weeks of gestation born in 2014-2016 and admitted to tertiary neonatal intensive care units (NICUs) of 9 population-based national or regional neonatal networks. Infants in NICUs receiving treatment of presymptomatic PDA identified by routine echocardiography and those not were compared for the primary composite outcome (early death [≤7 days after birth] or severe intraventricular hemorrhage) and secondary outcomes (any in-hospital mortality and major morbidities). RESULTS: The unit survey (response rates of 86%) revealed a wide variation among networks in the treatment of presymptomatic PDA (7%-86%). Among 246 NICUs with 17 936 infants (mean gestational age of 26 weeks), 126 NICUs (51%) with 7785 infants treated presymptomatic PDA. The primary outcome of early death or severe intraventricular hemorrhage was not significantly different between the NICUs treating presymptomatic PDA and those who did not (17% vs 21%; aOR 1.00, 95% CI 0.85-1.18). The NICUs treating presymptomatic PDA had greater odds of retinopathy of prematurity treatment (13% vs 7%; aOR 1.47, 95% CI 1.01-2.12); however, it was not significant in a sensitivity analysis excluding Japanese data. CONCLUSIONS: Treating presymptomatic PDA detected by routine echocardiography was commonplace but associated with no significant benefits. Well-designed trials are needed to assess the efficacy and safety of early targeted PDA treatment.

Family Rooms in Neonatal Intensive Care Units and Neonatal Outcomes: An International Survey and Linked Cohort Study.

OBJECTIVES: To evaluate the proportion of neonatal intensive care units with facilities supporting parental presence in their infants' rooms throughout the 24-hour day (ie, infant-parent rooms) in high-income countries and to analyze the association of this with outcomes of extremely preterm infants. STUDY DESIGN: In this survey and linked cohort study, we analyzed unit design and facilities for parents in 10 neonatal networks of 11 countries. We compared the composite outcome of mortality or major morbidity, length of stay, and individual morbidities between neonates admitted to units with and without infant-parent rooms by linking survey responses to patient data from 2015 for neonates of less than 29 weeks of gestation. RESULTS: Of 331 units, 13.3% (44/331) provided infant-parent rooms. Patient-level data were available for 4662 infants admitted to 159 units in 7 networks; 28% of the infants were cared for in units with infant-parent rooms. Neonates from units with infant-parent rooms had lower odds of mortality or major morbidity (aOR, 0.76; 95% CI, 0.64-0.89), including lower odds of sepsis and bronchopulmonary dysplasia, than those from units without infant-parent rooms. The adjusted mean length of stay was 3.4 days shorter (95%, CI -4.7 to -3.1) in the units with infant-parent rooms. CONCLUSIONS: The majority of units in high-income countries lack facilities to support parents' presence in their infants' rooms 24 hours per day. The availability vs absence of infant-parent rooms was associated with lower odds of composite outcome of mortality or major morbidity and a shorter length of stay.

Survey shows marked variations in approaches to redirection of care for critically ill very preterm infants in 11 countries.

AIM: We surveyed care practices for critically ill very preterm infants admitted to neonatal intensive care units (NICUs) in the International Network for Evaluating Outcomes in Neonates (iNeo) to identify differences relevant to outcome comparisons. METHODS: We conducted an online survey on care practices for critically ill very preterm infants and infants with severe intracranial haemorrhage (ICH). The survey was distributed in 2015 to representatives of 390 NICUs in 11 countries. Survey replies were compared with network incidence of death and severe ICH for infants born between 230/7 and 286/7  weeks of gestation from January 1, 2015, to December 31, 2015. RESULTS: Most units in Israel, Japan and Tuscany, Italy, favoured withholding care when care was considered futile, whereas most units in other networks favoured redirection of care. For infants with bilateral grade 4 ICH, redirection of care was very frequently (≥90% of cases) offered in the majority of units in Australia and New Zealand and Switzerland, but rarely in other networks. Networks where redirection of care was frequently offered for severe ICH had lower rates of survivors with severe ICH. CONCLUSION: We identified marked inter-network differences in care approaches that need to be considered when comparing outcomes.

Isolation and characterization of patient-derived, toxic, high mass amyloid beta-protein (Abeta) assembly from Alzheimer disease brains.

Amyloid beta-protein (Abeta) assemblies are thought to play primary roles in Alzheimer disease (AD). They are considered to acquire surface tertiary structures, not present in physiologic monomers, that are responsible for exerting toxicity, probably through abnormal interactions with their target(s). Therefore, Abeta assemblies having distinct surface tertiary structures should cause neurotoxicity through distinct mechanisms. Aiming to clarify the molecular basis of neuronal loss, which is a central phenotype in neurodegenerative diseases such as AD, we report here the selective immunoisolation of neurotoxic 10-15-nm spherical Abeta assemblies termed native amylospheroids (native ASPDs) from AD and dementia with Lewy bodies brains, using ASPD tertiary structure-dependent antibodies. In AD patients, the amount of native ASPDs was correlated with the pathologic severity of disease. Native ASPDs are anti-pan oligomer A11 antibody-negative, high mass (>100 kDa) assemblies that induce degeneration particularly of mature neurons, including those of human origin, in vitro. Importantly, their immunospecificity strongly suggests that native ASPDs have a distinct surface tertiary structure from other reported assemblies such as dimers, Abeta-derived diffusible ligands, and A11-positive assemblies. Only ASPD tertiary structure-dependent antibodies could block ASPD-induced neurodegeneration. ASPDs bind presynaptic target(s) on mature neurons and have a mode of toxicity different from those of other assemblies, which have been reported to exert their toxicity through binding postsynaptic targets and probably perturbing glutamatergic synaptic transmission. Thus, our findings indicate that native ASPDs with a distinct toxic surface induce neuronal loss through a different mechanism from other Abeta assemblies.

Unit-Level Variations in Healthcare Professionals' Availability for Preterm Neonates <29 Weeks' Gestation: An International Survey.

INTRODUCTION: The availability of and variability in healthcare professionals in neonatal units in different countries has not been well characterized. Our objective was to identify variations in the healthcare professionals for preterm neonates in 10 national or regional neonatal networks participating in the International Network for Evaluating Outcomes (iNeo) of neonates. METHOD: Online, pre-piloted questionnaires about the availability of healthcare professionals were sent to the directors of 390 tertiary neonatal units in 10 international networks: Australia/New Zealand, Canada, Finland, Illinois, Israel, Japan, Spain, Sweden, Switzerland, and Tuscany. RESULTS: Overall, 325 of 390 units (83%) responded. About half of the units (48%; 156/325) cared for 11-30 neonates/day and had team-based (43%; 138/325) care models. Neonatologists were present 24 h a day in 59% of the units (191/325), junior doctors in 60% (194/325), and nurse practitioners in 36% (116/325). A nurse-to-patient ratio of 1:1 for infants who are unstable and require complex care was used in 52% of the units (170/325), whereas a ratio of 1:1 or 1:2 for neonates requiring multisystem support was available in 59% (192/325) of the units. Availability of a respiratory therapist (15%, 49/325), pharmacist (40%, 130/325), dietitian (34%, 112/325), social worker (81%, 263/325), lactation consultant (45%, 146/325), parent buddy (6%, 19/325), or parents' resource personnel (11%, 34/325) were widely variable between units. CONCLUSIONS: We identified variability in the availability and organization of the healthcare professionals between and within countries for the care of extremely preterm neonates. Further research is needed to associate healthcare workers' availability and outcomes.

Lowering the premature birth rate: what the U.S. experience means for Japan.

Premature birth rate and low birth weight rate are increasing in industrialized countries including USA and Japan. The Infant mortality rate (IMR) is three times and 50-75 times greater for infants born at 32-36 weeks and <32 weeks respectively than term-born counterparts. In the U.S., the IMR is greater than in Japan particularly among black infants and simply the "lower socioeconomic class" is not the answer. Premature birth is heterogeneous in origin and idiopathic in 70% of the cases. Increased utilization of assisted reproductive technology only accounts for a part of the recent trend. Evidence suggests environmental factors play a significant role, and genetic-environmental interaction is plausible. A chronic psychosocial stress of pregnant women has been postulated to be modifying the endocrine milieu thereby influencing pregnancy outcomes. In a preliminary observation in St. Louis, homeless pregnant women with high behavioral and social risks, when accommodated in a shelter home designed for these women, produced significantly less numbers of premature and low birth weight infants as compared with the general population. Furthermore, in a randomized controlled study in Washington DC, psychobehavioral intervention specifically targeting smoking (primary and secondary), intimate partner violence (IPV), and depression among black pregnant women significantly decreased the rate of miscarriage and low birth weight. These reports may have significant implication to the Japanese situation. Increasing number of Japanese women at reproductive age are exposed to smoking, may have underling psychosocial stress and may suffer from subclinical depression and/or from IPV. Detailed epidemiological studies of women before and during the reproductive age with regard to risk factors can lead to an effective intervention strategy against premature birth in Japan.

Respiratory Management of Extremely Preterm Infants: An International Survey.

BACKGROUND: There are significant international variations in chronic lung disease rates among very preterm infants yet there is little data on international variations in respiratory strategies. OBJECTIVE: To evaluate practice variations in the respiratory management of extremely preterm infants born at < 29 weeks' gestational age (GA) among 10 neonatal networks participating in the International Network for Evaluating Outcomes (iNeo) of Neonates collaboration. METHODS: A web-based survey was sent to the representatives of 390 neonatal intensive care units from Australia/New Zealand, Canada, Finland, Illinois (USA), Israel, Japan, Spain, Sweden, Switzerland, and Tuscany (Italy). Responses were based on practices in 2015. RESULTS: Overall, 321 of the 390 units responded (82%). The majority of units within networks (40-92%) mechanically ventilate infants born at 23-24 weeks' GA on continuous positive airway pressure (CPAP) with 30-39% oxygen in respiratory distress within 48 h after birth, but the proportion of units that offer mechanical ventilation for infants born at 25-26 weeks' GA at similar settings varied significantly (20-85% of units within networks). The most common respiratory strategy for infants born at 27-28 weeks' GA on CPAP with 30-39% oxygen with respiratory distress within 48 h after birth used by units also varied significantly among networks: mechanical ventilation (0-60%), CPAP (3-82%), intubation and surfactant administration with immediate extubation (0-75%), and less invasive surfactant administration (0-68%). CONCLUSIONS: There are marked variations but also similarities in respiratory management of extremely preterm infants between networks. Further collaboration and exploration is needed to better understand the association of these variations in practice with pulmonary outcomes.

Variations in Oxygen Saturation Targeting, and Retinopathy of Prematurity Screening and Treatment Criteria in Neonatal Intensive Care Units: An International Survey.

BACKGROUND: Rates of retinopathy of prematurity (ROP) and ROP treatment vary between neonatal intensive care units (NICUs). Neonatal care practices, including oxygen saturation (SpO2) targets and criteria for the screening and treatment of ROP, are potential contributing factors to the variations. OBJECTIVES: To survey variations in SpO2 targets in 2015 (and whether there had been recent changes) and criteria for ROP screening and treatment across the networks of the International Network for Evaluating Outcomes in Neonates (iNeo). METHODS: Online prepiloted questionnaires on treatment practices for preterm infants were sent to the directors of 390 NICUs in 10 collaborating iNeo networks. Nine questions were asked and the results were summarized and compared. RESULTS: Overall, 329/390 (84%) NICUs responded, and a majority (60%) recently made changes in upper and lower SpO2 target limits, with the median set higher than previously by 2-3% in 8 of 10 networks. After the changes, fewer NICUs (15 vs. 28%) set an upper SpO2 target limit > 95% and fewer (3 vs. 5%) a lower limit < 85%. There were variations in ROP screening criteria, and only in the Swedish network did all NICUs follow a single guideline. The initial retinal examination was carried out by an ophthalmologist in all but 6 NICUs, and retinal photography was used in 20% but most commonly as an adjunct to indirect ophthalmoscopy. CONCLUSIONS: There is considerable variation in SpO2 targets and ROP screening and treatment criteria, both within networks and between countries.

Differences in methylation patterns in the methylation boundary region of IDS gene in Hunter syndrome patients: implications for CpG hot spot mutations.

Hunter syndrome, an X-linked disorder, results from deficiency of iduronate-2-sulfatase (IDS). Around 40% of independent point mutations at IDS were found at CpG sites as transitional events. The 15 CpG sites in the coding sequences of exons 1 and 2, which are normally hypomethylated, account for very few of transitional mutations. By contrast, the CpG sites in the coding sequences of exon 3, though also normally hypomethylated, account for much higher fraction of transitional mutations. To better understand relationship between methylation status and CpG transitional mutations in this region, the methylation patterns of 11 Hunter patients with transitional mutations at CpG sites were investigated using bisulfite genomic sequencing. The patient cohort mutation spectrum is composed of one mutation in exon 1 (one patient) and three different mutations in exon 3 (10 patients). We confirmed that in normal males, cytosines at the CpG sites from the promoter region to a portion of intron 3 were hypomethylated. However, specific CpG sites in this area were more highly methylated in patients. The patients with p.R8X (exon 1), p.P86L (exon 3), and p.R88H (exon 3) mutations had a hypermethylated condition in exon 2 to intron 3 but retained hypomethylation in exon 1. The same trend was found in four patients with p.A85T (exon 3), although the degree of hypermethylation was less. These findings suggest methylation patterns in the beginning of IDS genomic region are polymorphic in humans and that hypermethylation in this region in some individuals predisposes them to CpG mutations resulting in Hunter syndrome.

Mutation and polymorphism spectrum of the GALNS gene in mucopolysaccharidosis IVA (Morquio A).

Mucopolysaccharidosis IVA (MPS IVA; Morquio A disease) is an autosomal-recessive disorder caused by a deficiency of lysosomal N-acetylgalactosamine-6-sulfate sulfatase (GALNS; E.C.3.1.6.4). GALNS is required to degrade glycosaminoglycans, keratan sulfate (KS), and chondroitin-6-sulfate. Accumulation of undegraded substrates in lysosomes of the affected tissues leads to a systemic bone dysplasia. We summarize information on 148 unique mutations determined to date in the GALNS gene, including 26 novel mutations (19 missense, four small deletions, one splice-site, and two insertions). This heterogeneity in GALNS gene mutations accounts for an extensive clinical variability within MPS IVA. Seven polymorphisms that cause an amino acid change, and nine silent variants in the coding region are also described. Of the analyzed mutant alleles, missense mutations accounted for 78.4%; small deletions, 9.2%; nonsense mutation, 5.0%; large deletion, 2.4%; and insertions, 1.6%. Transitional mutations at CpG dinucleotides accounted for 26.4% of all the described mutations. The importance of the relationship between methylation status and distribution of transitional mutations at CpG sites at the GALNS gene locus was elucidated. The three most frequent mutations (over 5% of all mutations) were represented by missense mutations (p.R386C, p.G301C, and p.I113F). A genotype/phenotype correlation was defined in some mutations. Missense mutations associated with a certain phenotype were studied for their effects on enzyme activity and stability, the levels of blood and urine KS, the location of mutations with regard to the tertiary structure, and the loci of the altered amino acid residues among sulfatase proteins.

Effect of Catheter Dwell Time on Risk of Central Line-Associated Bloodstream Infection in Infants.

BACKGROUND AND OBJECTIVE: Central venous catheters in the NICU are associated with significant morbidity and mortality because of the risk of central line-associated bloodstream infections (CLABSIs). The purpose of this study was to determine the effect of catheter dwell time on risk of CLABSI. METHODS: Retrospective cohort study of 13,327 infants with 15,567 catheters (93% peripherally inserted central catheters [PICCs], 7% tunneled catheters) and 256,088 catheter days cared for in 141 NICUs. CLABSI was defined using National Health Surveillance Network criteria. We defined dwell time as the number of days from line insertion until either line removal or day of CLABSI. We generated survival curves for each week of dwell time and estimated hazard ratios for CLABSI at each week by using a Cox proportional hazards frailty model. We controlled for postmenstrual age and year, included facility as a random effect, and generated separate models by line type. RESULTS: Median postmenstrual age was 29 weeks (interquartile range 26-33). The overall incidence of CLABSI was 0.93 per 1000 catheter days. Increased dwell time was not associated with increased risk of CLABSI for PICCs. For tunneled catheters, infection incidence was significantly higher in weeks 7 and 9 compared with week 1. CONCLUSIONS: Clinicians should not routinely replace uninfected PICCs for fear of infection but should consider removing tunneled catheters before week 7 if no longer needed. Additional studies are needed to determine what daily maintenance practices may be associated with decreased risk of infection, especially for tunneled catheters.

General implications for CpG hot spot mutations: methylation patterns of the human iduronate-2-sulfatase gene locus.

The methylation pattern at CpG sites of a housekeeping gene correlates with the likelihood of mutation. Mucopolysaccharidosis (MPS) type II, an X-linked disorder, results from the deficiency of iduronate-2-sulfatase (IDS). In these patients, over 35% of independent point mutations at the IDS gene locus were found at CpG sites as transitional events. To gain insight into the relationship between methylation status and CpG hot spot mutations, we investigated patterns of cytosine methylation in the entire IDS gene, except for introns 4-8. Bisulfite genomic sequencing was performed on the normal leukocyte DNA. Our data show that: 1) cytosine methylation at the CpG sites was extensive, except for those present from the promoter region to a portion of intron 3; 2) a sharp boundary of methylated-nonmethylated regions was observed at the 5'-flanking region, whereas a gradual change in methylation was observed in the 2.0-kb segment in the 3'-flanking region; 3) the boundary of the 5'-flanking region contained multiple Sp1 sites and the TATA box; 4) the CpG sites in exons 1 and 2 were hypomethylated and were associated only with rare transitional mutations, while the CpG sites in exon 3 were also hypomethylated, yet were associated with a high rate of transitional mutations; 5) there was no striking sex difference in the methylation patterns in active alleles; and, 6) the methylation in both strands was symmetrical, except at the boundary of methylated-unmethylated regions.

Mucopolysaccharidosis IVA (Morquio A): identification of novel common mutations in the N-acetylgalactosamine-6-sulfate sulfatase (GALNS) gene in Italian patients.

Mucopolysaccharidosis IVA (MPS IVA) is a lysosomal storage disorder caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Mutation screening of the GALNS gene was performed by RT-PCR with one amplicon and direct sequence analyses using cDNA samples from 15 Italian MPS IVA patients. Each mutation was confirmed at the genomic level. In this study, 13 different gene mutations with four common mutations (over 10% of mutant alleles) were identified in 12 severe and three milder (attenuated) MPS IVA patients. The gene alterations in 12 out of 13 were found to be point mutations and only one mutation was deletion. Ten of 13 mutations were novel. The c.1070C>T (p.Pro357Leu) mutation coexisted with c.1156C>T (p.Arg386Cys) mutation on the same allele. Together they accounted for 100% of the 30 disease alleles of the patients investigated. Four common mutations accounted for 70% of mutant alleles investigated. Urine keratan sulfate (KS) concentrations were elevated in all patients investigated. These data provide further evidence for extensive allelic heterogeneity and importance of relation among genotype, phenotype, and urine KS excretion as a biomarker in MPS IVA.

Body mass index change between pregnancies and small for gestational age births.

OBJECTIVE: To estimate whether maternal weight changes between pregnancies influence the risk for small for gestational age (SGA) births. METHODS: SGA cases (n = 8,062) below the tenth percentile birth weight for gestational age were selected from liveborn singletons born of Missouri residents during 1989-1997. Normal weight controls (n = 8,062) were selected according to birth year. The risk of SGA from interpregnancy body mass index (BMI) change and other maternal factors was estimated using logistic regression analysis. RESULTS: An increase in BMI between pregnancies decreased SGA risk (adjusted odds ratio = 0.8; 95% confidence interval 0.7, 1.0). Other risk factors were prior SGA (4.4; 4.0, 4.8), preeclampsia/eclampsia (2.6; 2.1, 3.2), maternal cardiac disease (1.8; 1.1, 2.9), inadequate weight gain (1.9; 1.8, 2.2), and cigarette smoking (1.9; 1.7, 2.3 for 1-9 cigarettes per day; 2.5; 2.2, 2.8 for 10-19/d; and 2.8; 2.5, 3.3 for 20/d or more). CONCLUSION: Increase in interpregnancy BMI lowers SGA risk, but adequate weight gain during pregnancy is more effective.

Murine model (Galns(tm(C76S)slu)) of MPS IVA with missense mutation at the active site cysteine conserved among sulfatase proteins.

Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive disorder caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), required for degradation of keratan sulfate and chondroitin-6-sulfate. In order to study the effects of a missense mutation in the active site cysteine in the GALNS gene that is conserved in all mammalian sulfatases, we produced a p.C76S (an active site replacement) knock-in mouse by replacing the Cys76 with Ser in the endogenous murine Galns by targeted mutagenesis. Homozygous Galns(tm(C76S)slu) mice had no detectable GALNS enzyme activity. At age of 2-4 months, lysosomal storage was present primarily within reticuloendothelial cells such as Kupffer cells and spleen sinusoidal lining cells. Vacuolar change was present in glomerular visceral epithelial cells and was not present in hepatocytes or renal tubular cells. In the brain, hippocampal and neocortical neurons and meningeal cells showed lysosomal storage. Radiographs revealed no change in the skeletal bones of mice up to 12 months old. Thus, the Galns(tm(C76S)slu) mice had visceral storage of GAGs in organs but lacked the skeletal features of human MPS IVA. In contrast to a previously reported transgenic model (Galns(tm(hC79S.mC76S)slu)), in which the inactive human GALNS transgene was overexpressed, no reduction in other sulfatases was observed. In addition, the Galns(tm(C76S)slu) mice displayed milder storage. We conclude that the milder phenotype is characteristic of isolated GALNS deficiency while the more severe phenotype reflected in the Galns(tm(hC79S.mC76S)slu) mice was due to deficiency of other sulfatases caused by oversaturation of the sulfate modifying enzyme by the inactive human gene product.

Determinant factors of spectrum of missense variants in mucopolysaccharidosis IVA gene.

Design of efficient treatment strategies for diseases requires clarification of the nature of each mutation causing the disease. In this study, we have investigated three factors to correctly predict the correlation between genotype and phenotype on N-acetylgalactosamine-6-sulfate sulfatase (GALNS) gene responsible for one of lysosomal storage diseases, known as mucopolysaccharidosis IVA (MPS IVA); (i) evolutionary conservation of amino acid residues among family proteins, (ii) conservativeness of amino acid changes in GALNS, and (iii) structural conservation of amino acid residue. The results showed that (i) the likelihood of a missense variant causing MPS IVA was directly correlated with the level of evolutionary conservation and inversely correlated with conservativeness but not correlated with the structural conservation, (ii) the disease-causative mutations were 9 times more likely to be located on the 'highly conserved' residues than the polymorphisms, (iii) the likelihood of 'non-conservative' amino acid changes in missense mutations was 6.8 times higher than those in the polymorphisms, (iv) the degree of evolutionary conservation was nearly as predictive in phenotype as that of conservativeness of amino acid changes, and (v) the combination of the two factors, evolutionary conservation and conservativeness, provides a better association between missense variants and clinical severity with higher sensitivity (83.5-88.9%) and specificity (71.4-88.3%), than that obtained by either factor alone. These findings suggest that the combination of evolutionary conservation and conservativeness is a useful tool to predict the effect of each mutation on the clinical phenotype and can be applied to the analysis of phenotype/genotype relation in other genetic diseases.

Enhancement of drug delivery to bone: characterization of human tissue-nonspecific alkaline phosphatase tagged with an acidic oligopeptide.

Hypophosphatasia is caused by deficiency of activity of the tissue-nonspecific alkaline phosphatase (TNSALP), resulting in a defect of bone mineralization. Enzyme replacement therapy (ERT) with partially purified plasma enzyme was attempted but with little clinical improvement. Attaining clinical effectiveness with ERT for hypophosphatasia may require delivering functional TNSALP enzyme to bone. We tagged the C-terminal-anchorless TNSALP enzyme with an acidic oligopeptide (a six or eight residue stretch of L-Asp), and compared the biochemical properties of the purified tagged and untagged enzymes derived from Chinese hamster ovary cell lines. The specific activities of the purified enzymes tagged with the acidic oligopeptide were the same as the untagged enzyme. In vitro affinity experiments showed the tagged enzymes had 30-fold higher affinity for hydroxyapatite than the untagged enzyme. Lectin affinity chromatography for carbohydrate structure showed little difference among the three enzymes. Biodistribution pattern from single infusion of the fluorescence-labeled enzymes into mice showed delayed clearance from the plasma up to 18 h post infusion and the amount of tagged enzyme retained in bone was 4-fold greater than that of the untagged enzyme. In vitro mineralization assays with the bone marrow from a hypophosphatasia patient using each of the three enzymes in the presence of high concentrations of pyrophosphate provided evidence of bone mineralization. These results show the anchorless enzymes tagged with an acidic oligopeptide are delivered efficiently to bone and function bioactively in bone mineralization, at least in vitro. They suggest potential advantages for use of these tagged enzymes in ERT for hypophosphatasia, which should be explored.

Development of MPS IVA mouse (Galnstm(hC79S.mC76S)slu) tolerant to human N-acetylgalactosamine-6-sulfate sulfatase.

Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive disease caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency. In recent studies of enzyme replacement therapy for animal models with lysosomal storage diseases, cellular and humoral immune responses to the injected enzymes have been recognized as major impediments to effective treatment. To study the long-term effectiveness and side effects of therapies in the absence of immune responses, we have developed an MPS IVA mouse model, which has many similarities to human MPS IVA and is tolerant to human GALNS protein. We used a construct containing both a transgene (cDNA) expressing inactive human GALNS in intron 1 and an active site mutation (C76S) in adjacent exon 2 and thereby introduced both the inactive cDNA and the C76S mutation into the murine Galns by targeted mutagenesis. Affected homozygous mice have no detectable GALNS enzyme activity and accumulate glycosaminoglycans in multiple tissues including visceral organs, brain, cornea, bone, ligament and bone marrow. At 3 months, lysosomal storage is marked within hepatocytes, reticuloendothelial Kupffer cells, and cells of the sinusoidal lining of the spleen, neurons and meningeal cells. The bone storage is also obvious, with lysosomal distention in osteoblasts and osteocytes lining the cortical bone, in chondrocytes and in the sinus lining cells in bone marrow. Ubiquitous expression of the inactive human GALNS was also confirmed by western blot using the anti-GALNS monoclonal antibodies newly produced, which resulted in tolerance to immune challenge with human enzyme. The newly generated MPS IVA mouse model should provide a good model to evaluate long-term administration of enzyme replacement.

Spherical aggregates of beta-amyloid (amylospheroid) show high neurotoxicity and activate tau protein kinase I/glycogen synthase kinase-3beta.

beta-Amyloid (Abeta) acquires toxicity by self-aggregation. To identify and characterize the toxic form(s) of Abeta aggregates, we examined in vitro aggregation conditions by using large quantities of homogenous, chemically synthesized Abeta1-40 peptide. We found that slow rotation of Abeta1-40 solution reproducibly gave self-aggregated Abeta1-40 containing a stable and highly toxic moiety. Examination of the aggregates purified by glycerol-gradient centrifugation by atomic force microscopy and transmission electron microscopy revealed that the toxic moiety is a perfect sphere, which we call amylospheroid (ASPD). Other Abeta1-40 aggregates, including fibrils, were nontoxic. Correlation studies between toxicity and sphere size indicate that 10- to 15-nm ASPD was highly toxic, whereas ASPD <10 nm was nontoxic. A positive correlation between the toxicity and ASPD >10 nm also appeared to exist when Abeta1-42 formed ASPD by slow rotation. However, Abeta1-42-ASPD formed more rapidly, killed neurons at lower concentrations, and showed approximately 100-fold-higher toxicity than Abeta1-40-ASPD. The toxic ASPD was associated with SDS-resistant oligomeric bands in immunoblotting, which were absent in nontoxic ASPD. Because the formation of ASPD was not disturbed by pentapeptides that break beta-sheet interactions, Abeta may form ASPD through a pathway that is at least partly distinct from that of fibril formation. Inhibition experiments with lithium suggest the involvement of tau protein kinase I/glycogen synthase kinase-3beta in the early stages of ASPD-induced neurodegeneration. Here we describe the identification and characterization of ASPD and discuss its possible role in the neurodegeneration in Alzheimer's disease.

Efficacy of albuterol inhalation in treatment of hyperkalemia in premature neonates.

OBJECTIVE: To evaluate the efficacy of inhaled albuterol for treatment of hyperkalemia in premature neonates by conducting a prospective, randomized placebo-controlled and double-blinded clinical trial. STUDY DESIGN: Neonates <2000 g receiving mechanical ventilation with central serum potassium > or =6.0 mmol/L (6.0 mEq/L), were randomly assigned to treatment or placebo groups. Albuterol (400 microg) or saline was given by nebulization. The dose was repeated every 2 hours until the potassium level fell below 5 mmol/L (maximum 12 doses) or there were signs of toxicity. RESULTS: Nineteen patients completed the study (8 in the albuterol and 11 in the saline group). Serum potassium levels declined rapidly in the first 4 hours in the albuterol group, from 7.06 +/- 0.23 mmol/L to 6.34 +/- 0.24 mmol/L (P =.003) versus no significant change in the saline group (6.88 +/- 0.18 mmol/L to 6.85 +/- 0.24 mmol/L; P =.87). At 8 hours, the fall continued to be greater in the albuterol group versus the saline group (5.93 +/- 0.3 mmol/L and 6.35 +/- 0.22 mmol/L, respectively; P =.04). CONCLUSION: Albuterol inhalation may be useful in rapidly lowering serum potassium levels in premature neonates.