The Sensitivity of Euro-Atlantic Regimes to Model Horizontal Resolution.

There is growing evidence that the atmospheric dynamics of the Euro-Atlantic sector during winter is driven in part by the presence of quasi-persistent regimes. However, general circulation models typically struggle to simulate these with, for example, an overly weakly persistent blocking regime. Previous studies have showed that increased horizontal resolution can improve the regime structure of a model but have so far only considered a single model with only one ensemble member at each resolution, leaving open the possibility that this may be either coincidental or model dependent. We show that the improvement in regime structure due to increased resolution is robust across multiple models with multiple ensemble members. However, while the high-resolution models have notably more tightly clustered data, other aspects of the regimes may not necessarily improve and are also subject to a large amount of sampling variability that typically requires at least three ensemble members to surmount.

Dynamic self-assembly of DNA minor groove-binding ligand DB921 into nanotubes triggered by an alkali halide.

We describe a novel self-assembling supramolecular nanotube system formed by a heterocyclic cationic molecule which was originally designed for its potential as an antiparasitic and DNA sequence recognition agent. Our structural characterisation work indicates that the nanotubes form via a hierarchical assembly mechanism that can be triggered and tuned by well-defined concentrations of simple alkali halide salts in water. The nanotubes assembled in NaCl have inner and outer diameters of ca. 22 nm and 26 nm respectively, with lengths that reach into several microns. Our results suggest the tubes consist of DB921 molecules stacked along the direction of the nanotube long axis. The tubes are stabilised by face-to-face π-π stacking and ionic interactions between the charged amidinium groups of the ligand and the negative halide ions. The assembly process of the nanotubes was followed using small-angle X-ray and neutron scattering, transmission electron microscopy and ultraviolet/visible spectroscopy. Our data demonstrate that assembly occurs through the formation of intermediate ribbon-like structures that in turn form helices that tighten and compact to form the final stable filament. This assembly process was tested using different alkali-metal salts, showing a strong preference for chloride or bromide anions and with little dependency on the type of cation. Our data further demonstrates the existence of a critical anion concentration above which the rate of self-assembly is greatly enhanced.

Enhanced sealing strength of a hydrophobically-modified Alaska pollock gelatin-based sealant.

The aim of this study was the development of an innovative biocompatible sealant composed of Alaska pollock-derived gelatin partially modified with a dodecyl group (C12-ApGltn) and a poly(ethylene glycol)-based crosslinker, pentaerythritol poly(ethylene glycol) ether tetrasuccinimidyl glutarate. The burst strength of the developed sealants was measured using porcine aorta and rat lungs. The maximum burst strength of a C12-ApGltn-based sealant against the porcine aorta was 4-fold higher than that of an original ApGltn (Org-ApGltn)-based sealant. No significant increase in the burst strength was observed between C12-ApGltn-based sealants with 4.2 and 8.9 mol% modification ratios. From histological observation after burst strength measurement, tissue tearing was observed when a C12-ApGltn-based sealant was applied. In contrast, the Org-ApGltn-based sealant was peeled away from the aorta surface due to cohesion failure. Similar to the porcine aorta, the burst strength of C12-ApGltn-based sealants applied on a rat lung defect was 3-fold higher than that of an Org-ApGltn-based sealant. The curing time of the C12-ApGltn-based sealant measured by a simple mixing method was shorter (2.6 ± 0.1 s) than that of the Org-ApGltn-based sealant (4.1 ± 0.3 s). The swelling ratio of the C12-ApGltn-based sealant (23.7 ± 3.1) was significantly lower than that of the Org-ApGltn-based sealant (32.3 ± 1.1). The C12-ApGltn-based sealant was completely degraded within 28 days after implantation in the backs of rats without a severe inflammation reaction. However, the Org-ApGltn-based sealant disappeared within 14 days. These results indicated that hydrophobically-modified ApGltn has an effective sealing effect on moist tissues and biocompatibility in vivo.

Stage-specific expression of DNasegamma during B-cell development and its role in B-cell receptor-mediated apoptosis in WEHI-231 cells.

Here, we describe the non-redundant roles of caspase-activated DNase (CAD) and DNasegamma during apoptosis in the immature B-cell line WEHI-231. These cells induce DNA-ladder formation and nuclear fragmentation by activating CAD during cytotoxic drug-induced apoptosis. Moreover, these apoptotic manifestations are accompanied by inhibitor of CAD (ICAD) cleavage and are abrogated by the constitutive expression of a caspase-resistant ICAD mutant. No such nuclear changes occur during oxidative stress-induced necrosis, indicating that neither CAD nor DNasegamma functions under necrotic conditions. Interestingly, the DNA-ladder formation and nuclear fragmentation induced by B-cell receptor ligation occur in the absence of ICAD cleavage and are not significantly affected by the ICAD mutant. Both types of nuclear changes are preceded by the upregulation of DNasegamma expression and are strongly suppressed by 4-(4,6-dichloro-[1, 3, 5]-triazin-2-ylamino)-2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-benzoic acid (DR396), which is a specific inhibitor of DNasegamma. Our results suggest that DNasegamma provides an alternative mechanism for inducing nuclear changes when the working apoptotic cascade is unsuitable for CAD activation.

Total body bone development during early childhood in very low birth weight infants without cerebral palsy and mental retardation.

Total body bone mineral density was measured by dual energy X-ray absorptiometry in 52 children who were very low birth weight (VLBW) infants without cerebral palsy and mental retardation (postconceptional age, from 10 mo to 6 y and 6 mo). VLBW infants in this study seemed to show compensatory acceleration of total body bone development, catching up with the control group during early childhood. However, in VLBW infants with at least one of the three factors such as total parenteral nutrition for 1 week or more, assisted ventilation for 1 week or more, or oxygen therapy for 28 d or more in their early stage after birth, adequate mineral supplementation might be especially important for long-term bone development.

The XRCC4 gene product is a target for and interacts with the DNA-dependent protein kinase.

The gene product of XRCC4 has been implicated in both V(D)J recombination and the more general process of double strand break repair (DSBR). To date its role in these processes is unknown. Here, we describe biochemical characteristics of the murine XRCC4 protein. XRCC4 expressed in insect cells exists primarily as a disulfide-linked homodimer, although it can also form large multimers. Recombinant XRCC4 is phosphorylated during expression in insect cells. XRCC4 phosphorylation in Sf9 cells occurs on serine, threonine, and tyrosine residues. We also investigated whether XRCC4 interacts with the other factor known to be requisite for both V(D)J recombination and DSBR, the DNA-dependent protein kinase. We report that XRCC4 is an efficient in vitro substrate of DNA-PK and another unidentified serine/ threonine protein kinase(s). Both DNA-PK dependent and independent phosphorylation of XRCC4 in vitro occurs only on serine and threonine residues within the COOH-terminal 130 amino acids, a region of the molecule that is not absolutely required for XRCC4's DSBR function. Finally, recombinant XRCC4 facilitates Ku binding to DNA, promoting assembly of DNA-PK and complexing with DNA-PK bound to DNA. These data are consistent with the hypothesis that XRCC4 functions as an alignment factor in the DNA-PK complex.

An autopsy case of bathtub drowning in epilepsy.

We report an autopsy case of bathtub drowning in epilepsy. A 26-year-old female with mental retardation had been treated for refractory epilepsy. Her younger sister found her floating supine in the bathtub 45 min after starting bathing. Neuropathological examination revealed cerebral cortical dysplasia in the precentral gyrus of the left hemisphere, which had not been detected by MRI, suggesting the etiology of epilepsy. In bathtub submersion injury of an unidentified cause, neuropathological examination should be performed to reveal any lesion underlying epileptic seizures. Additionally, we present statistics on bathtub submersion injury in children aged 5 years or older in Japan based upon nationwide survey data obtained in 1991. Forty-seven percent of them had associated epilepsy or convulsive attacks and 71% died. It is necessary for epileptic patients and their families to understand that the risk of bathtub drowning can be minimized if proper precautions are taken.

Molecular genetic characterization of XRCC4 function.

XRCC4 is a generally expressed protein of 334 amino acids that is involved in the repair of DNA double-strand breaks and in V(D)J recombination, but its function is unknown. In this study, we have used a mutational approach and the yeast two-hybrid method to perform an initial characterization of this protein. We show that the XRCC4 protein is located in the nucleus. We also demonstrate that several potential phosphorylation sites are not required for XRCC4 function in a transient V(D)J recombination assay. In addition, we show that XRCC4 forms a homodimer in vivo with the homodimerization domain being located within amino acids 115-204. Finally, we define a core domain of XRCC4 that functions in V(D)J recombination and comprises amino acids 18-204. Potential functions of XRCC4 are discussed.

RAB22 and RAB163/mouse BRCA2: proteins that specifically interact with the RAD51 protein.

The human RAD51 protein is a homologue of the bacteria RecA and yeast RAD51 proteins that are involved in homologous recombination and DNA repair. RAD51 interacts with proteins involved in recombination and also with tumor suppressor proteins p53 and breast cancer susceptibility gene 1 (BRCA1). We have used the yeast two-hybrid system to clone murine cDNA sequences that encode two RAD51-associated molecules, RAB22 and RAB163. RAB163 encodes the C-terminal portion of mouse BRCA2, the homologue of the second breast cancer susceptibility gene protein in humans, demonstrating an in vitro association between RAD51 and BRCA2. RAB22 is a novel gene product that also interacts with RAD51 in vitro. To detect RAD51 interactions in vivo, we developed a transient nuclear focus assay that was used to demonstrate a complete colocalization of RAB22 with RAD51 in large nuclear foci.

Evidence of brain ischemia in early neonatal sudden death syndrome.

Ten early neonatal sudden death victims (ENSD) were selected for neuropathological and immunohistochemical examinations. The gestational ages of the victims ranged from 36 to 42 weeks, and the postnatal ages from 8 hours to 10 days of life. In 6 of 10 patients, softening with rarefaction was observed in the subcortical or intermediate white matter, which was associated with minimal astrogliosis in the whole white matter. In 7 of the 10 ENSD victims, the number of GFAP-positive glia was significantly greater in both the deep and subcortical white matter than in controls. The brainstem showed mild gliosis in the reticular formation and vagal nuclei of the medulla oblongata in 8 of the 10 ENSD victims. In 8 of the 10 ENSD victims, the number of GFAP-positive astrocytes was greater in both the dorsal vagal nucleus and the reticular formation of the medulla oblongata than in controls. The high incidence of leukomalacia and astrogliosis in the cerebral white matter and brainstem suggests the presence of brain ischemic insults before death, which may be prenatal in some cases.

Relationship of substance P and gliosis in medulla oblongata in neonatal sudden infant death syndrome.

Substance P and glial fibrillary acidic protein (GFAP) immunohistochemistry was applied to the medulla of neonatal infants who died of sudden infant death syndrome (SIDS). A quantitative analysis of cells demonstrating immunoreactivity to GFAP and substance P in 15 neonatal SIDS cases revealed increased GFAP immunoreactivity in the reticular formation, the dorsal vagal nucleus, and the solitary nucleus and an increase in substance P immunoreactivity in the spinal trigeminal nucleus and the solitary nucleus as compared with that in age-matched controls. GFAP immunopositivity suggests astrogliosis which implies a pathologic insult to neurons in the area of astrogliosis. The failure of neurons in these sites to show enhanced substance P immunopositivity may indirectly indicate altered neurons. Further study of prenatal events may be of importance in clarifying the pathogenesis of neonatal SIDS.

The V(D)J recombination defect in the xrs-6 cell line results from a point mutation in the Ku80 gene.

Defective expression of the Ku80 gene has been implicated as underlying the V(D)J recombination and DNA double-strand break repair defects in the xrs-6 Chinese hamster ovary cell line. We now show that the mutation in the Ku80 gene involves a G to A transition 15 bp upstream of exon 2. This mutation creates a new splice acceptor site which results in the generation of Ku80 transcript that cannot encode a functional product due a 13 nucleotide insertion and a resulting frameshift.

Defective DNA-dependent protein kinase activity is linked to V(D)J recombination and DNA repair defects associated with the murine scid mutation.

Murine cells homozygous for the severe combined immune deficiency mutation (scid) and V3 mutant hamster cells fall into the same complementation group and show similar defects in V(D)J recombination and DNA double-stranded break repair. Here we show that both cell types lack DNA-dependent protein kinase (DNA-PK) activity owing to defects in DNA-PKcs, the catalytic subunit of this enzyme. Furthermore, we demonstrate that yeast artificial chromosomes containing the DNA-PKcs gene complement both the DNA repair and recombination deficiencies of V3 cells, and we conclude that DNA-PKcs is encoded by the XRCC7 gene. As DNA-PK binds to DNA ends and is activated by these structures, our findings provide novel insights into V(D)J recombination and DNA repair processes.

Ku80: product of the XRCC5 gene and its role in DNA repair and V(D)J recombination.

The radiosensitive mutant xrs-6, derived from Chinese hamster ovary cells, is defective in DNA double-strand break repair and in ability to undergo V(D)J recombination. The human XRCC5 DNA repair gene, which complements this mutant, is shown here through genetic and biochemical evidence to be the 80-kilodalton subunit of the Ku protein. Ku binds to free double-stranded DNA ends and is the DNA-binding component of the DNA-dependent protein kinase. Thus, the Ku protein is involved in DNA repair and in V(D)J recombination, and these results may also indicate a role for the Ku-DNA-dependent protein kinase complex in those same processes.

Isolation of adenovirus type 11 from the brain of a neonate with pneumonia and encephalitis.

We describe a fatal case of adenovirus pneumonia accompanied by encephalitis in a neonate who showed lethargy on the 6th day and died on the 12th day. Adenoviral particles as well as viral intranuclear inclusions were noted in pulmonary alveolar epithelium cells. Neuropathological examination revealed diffuse oedema, perivascular cuffing and gliosis in the white matter. Adenovirus type 11 was isolated from lung, hilar lymph node, and brain tissue. This is the first instance of adenovirus isolation from brain tissue in a newborn infant. The virological and neuropathological findings suggest the invasion of neural tissue by adenovirus and substantiate the significance of neurological symptoms observed in neonatal adenovirus infection.

Childhood drownings and near-drownings in Japan.

In Japan, the leading cause of death for children over 1 year old is injury, and for children aged 0-14, drowning is the second leading cause of death. The purpose of the present study was to describe the epidemiological factors of drownings and near-drowning among Japanese children and to ascertain whether there are characteristic patterns for different age groups. Epidemiologic data was obtained by questionnaire. A total of 604 cases of submersion injuries were reported from 49 hospitals located in 22 Japanese prefectures. In the present paper, victims of drowning (n = 134) and near-drowning with permanent severe brain damage (n = 51) and those of near-drowning with intact survival or mild impairment (n = 419) were investigated. Preschool-aged children, especially toddlers, are at the greatest risk of drowning and near-drowning, and for children over 2 years of age, boys have three times greater risk than girls. The bathtub is the most common place of submersion injuries in Japan, especially for children under 4 years of age. The important risk factors for the victims who died or were severely impaired were associated with duration of submersion and necessity of emergency cardiopulmonary resuscitation on arrival at hospital.

Treatment of an infant with congenital sodium diarrhea by oral rehydration.

We have been following a male case of congenital sodium diarrhea (CNaD), who had a distended abdomen, passed watery stools with high sodium concentration, and showed metabolic acidosis in the first week of life. He also showed hyponatremia, low urine sodium, high serum aldosterone and high renin activity. Other possible causes of secretory diarrhea were ruled out. The initial effective treatment was oral supplements of water and electrolytes lost in the fecal fluid: with this he gained weight, and hyponatremia and metabolic acidosis were corrected. Loperamide hydrochloride was administered to increase intestinal absorption of sodium, as the serum prostaglandin was high. Watery diarrhea then improved, but as he passed acholic stools, we stopped and postponed the treatment for a while; the stools then became watery again. Although diarrhea has persisted, he has not shown any abnormalities in growth or psychomotor development for the first two years of life.

[Electrophysiologic effects of intravenous digoxin in infants and children with Wolff-Parkinson-White syndrome].

Electrophysiologic properties of the accessory pathway were investigated before and after the intravenous administration of digoxin (0.01-0.02 mg/kg) during electrophysiologic studies in 14 infants and children with the Wolff-Parkinson-White syndrome. Determination of electrophysiologic properties of the accessory pathway was made using transesophageal atrial pacing and/or intracardiac right atrial pacing. Maximal effect on the accessory pathway after intravenous digoxin was observed during one to six hours. Effective refractory period of the accessory pathway increased in 6 of the 14 patients, decreased in 4 and unchanged in 4. Shortest AP 1:1 conduction increased in 5 of the 12 patients, decreased in 3 and unchanged in 4. Tachycardia was not induced after digoxin in only one patient. Tachycardia cycle length, ventriculoatrial conduction time and atrioventricular conduction time were unchanged after digoxin in almost all cases. Thus, digoxin is not the first choice drug for termination and prevention of the preexcitation syndrome.