Auditory event-related potentials during a spatial working memory task.

OBJECTIVE: Sensory cortical activity can be jointly governed by bottom-up (e.g. stimulus features) and top-down (e.g. memory, attention) factors. We tested the hypothesis that auditory sensory cortical activity is affected by encoding and retrieval of spatial information. METHODS: Auditory event-related potentials (ERPs) were recorded during working memory and passive listening conditions. Trials contained three noise bursts (two "items" at different locations, followed by a "probe"). In the working memory task subjects determined if the probe matched an item location. The influence of long-term memory was evaluated by training to one location that was always a non-match. Auditory ERPs were analyzed to items and probes (N100, P200, late positive wave-LPW). RESULTS: Reaction times varied significantly among probes (trained non-match

Identification of quantitative trait loci affecting sex determination in the Eastern treehole mosquito (Ochlerotatus triseriatus).

Laboratory colonies of the eastern treehole mosquito (Ochlerotatus triseriatus (Say)) exhibit a consistent female-biased sex ratio. This is unusual among mosquito species, in which heritable sex ratio distortion is usually male biased and mediated by meiotic drive. Quantitative trait loci (QTL) affecting sex were mapped in an F(1) intercross to better understand the genetics underlying this female bias. In P(1) and F(1) parents and in 146 F(2) individuals with a female-biased sex ratio (106 females:40 males), regions of seven cDNA loci were analyzed with single-strand conformation polymorphism (SSCP) analysis to identify and orient linkage groups. Genotypes were also scored at 73 random amplified polymorphic DNA (RAPD)-SSCP loci. In addition to the sex locus, at least four QTL affecting sex determination were detected with interval mapping on linkage groups I and II. Alleles at the sex locus cumulatively accounted for approximately 61-77% of the genetic variance in sex. Alleles at QTL adjacent to the sex locus and at a QTL on the opposite end of linkage group I increased the proportion of females, but alleles at a QTL on linkage group I and a second QTL on linkage group II increased the proportion of males. The female-biased sex ratio observed in laboratory colonies of O. triseriatus is most easily explained by the existence of multiple female biased distorter loci, as have been observed in other Diptera.

Controlled ileal release budesonide in pediatric Crohn disease: efficacy and effect on growth.

BACKGROUND: Although the effectiveness of controlled ileal release (CIR) budesonide in children can be extrapolated from adult studies, there are currently no data available concerning the effects of CIR budesonide therapy on linear growth. In the absence of controlled, prospective pediatric clinical trials, we reviewed the outcomes, particularly linear growth, of children and adolescents given CIR budesonide to treat active intestinal inflammation and to maintain remission. METHODS: Thirty-two children (20 males) aged 14.1 +/- 2.7 years with Crohn disease of the distal ileum with or without right colon involvement were treated for active Crohn disease (baseline Pediatric Crohn Disease Activity Index, 34 +/- 14) with 9 mg daily of CIR budesonide through the Hospital for Sick Children, University of Toronto, Inflammatory Bowel Diseases program. RESULTS: At first follow-up visit 8.7 +/- 6.0 weeks later, 19 of 32 (59%) were judged by the physician to have responded. In the subset of 22 patients who had laboratory tests repeated at the first follow-up visit, their Pediatric Crohn Disease Activity Index fell from 33 +/- 14 to 22 +/- 16 (P = 0.001). The Pediatric Crohn Disease Activity Index score fell to less than 15 (cut-off score remission) in 29%. Six prepubertal responders continued to receive 6 mg CIR budesonide for 6 to 13 months. Five of the 6 experienced only mild or no gastrointestinal symptoms and gained weight. Nevertheless, their mean height velocity was only 2.3 +/- 1.0 cm/year, and none grew at a rate of more than 4cm/year whilst receiving CIR budesonide. CONCLUSIONS: These data provide grade III evidence of modest effectiveness of CIR budesonide in children with active Crohn disease confined to the ileum with or without right colon involvement. The subnormal growth observed with continued therapy is concerning and may reflect either inadequately controlled intestinal inflammation or direct suppression of linear growth, as is observed with conventional corticosteroids. Randomized controlled pediatric trials of CIR budesonide must include parameters of linear growth as an outcome variable.

The use of alteplase to restore patency of central venous lines in pediatric patients: a cohort study.

We evaluated the efficacy and safety of alteplase to restore central venous line (CVL) patency in a consecutive cohort study. A uniform, weight-dependent protocol for alteplase administration was established prospectively. For children < or =10 kg, a dose of 0.5 mg was used; for children >10 kg, doses of 1 to 2 mg were used. The alteplase remained instilled for 1 to 4 hours or overnight. Retrospective data accrual found that 25 children received alteplase for a total of 34 courses; 29 (85%) of the 34 courses of alteplase completely restored CVL patency. Alteplase appears to be a safe and effective thrombolytic agent for CVL patency restoration in children.

Molecular epidemiology of human astroviruses.

Human astroviruses (HAstVs) are associated with 5-9 percent of cases of gastroenteritis in young children. Seven serotypes (HAstV-1 to -7), which correlate with genotypes, have been defined by using immune typing methods. We have used partial nucleotide sequence information from the capsid protein gene for molecular typing of 29 unique human astrovirus strains obtained from prospective studies of children with gastroenteritis in Egypt and Malawi. HAstV-1 was the most commonly detected strain, consistent with previous studies, but a surprising variety of strains were identified in both collections. An eighth astrovirus type, HAstV-8, has been defined on the basis of the complete capsid protein gene sequence and was detected in both collections analysed in this study. Although HAstV-8 and HAstV-4 strains segregate into well resolved clades by analysis of sequences from the region encoding protein P2 (VP32), the pair-wise distances between these types are less than those between strains of the other serotypes. In contrast, analysis of sequences from the region encoding protein P3 unambiguously resolve HAstV-4 and HAstV-8 strains, consistent with their classification as distinct serotypes. Overall, strains representing six of the eight serotypes were detected in two collections of samples from prospective studies of gastroenteritis in young children indicating that multiple astrovirus types are frequently co-circulating within communities.

Phylogeny of the major lineages of Membracoidea (Insecta: Hemiptera: Cicadomorpha) based on 28S rDNA sequences.

Analysis of sequences from a 3.5-kb region of the nuclear ribosomal 28S DNA gene spanning divergent domains D2-D10 supports the hypothesis, based on fossil, biogeographic, and behavioral evidence, that treehoppers (Aetalionidae and Membracidae) are derived from leafhoppers (Cicadellidae). Maximum-parsimony analysis indicated that treehoppers are the sister group of a lineage comprising the currently recognized cicadellid subfamilies Agalliinae, Megophthalminae, Adelungiinae, and Ulopinae. Based on this phylogenetic estimate, the derivation of treehoppers approximately coincided with shifts in physiology and behavior, including loss of brochosome production and a reversal from active, jumping nymphs to sessile, nonjumping nymphs. Myerslopiidae, traditionally placed as a tribe of the cicadellid subfamily Ulopinae, represented a basal lineage distinct from other extant membracoids. The analysis recovered a large leafhopper lineage comprising a polyphyletic Deltocephalinae (sensu stricto) and its apparent derivatives Koebeliinae, Eupelicinae (polyphyletic), Selenocephalinae, and Penthimiinae. Clades comprising Macropsinae, Neocoelidiinae, Scarinae, Iassinae, Coelidiinae, Eurymelinae + Idiocerinae, Evacanthini + Pagaroniini, Aphrodinae + Ledrinae (in part), Stenocotini + Tartessinae, and Cicadellini + Proconiini were also recovered with moderate to high branch support. Cicadellinae (sensu lato), Ledrinae, Typhlocybinae, and Xestocephalinae were consistently polyphyletic on the most-parsimonious topologies, but constraining these groups to be monophyletic did not significantly increase the length of the cladograms. Relationships among the major lineages received low branch support, suggesting that more data are needed to provide a robust phylogenetic estimate.

Thermal effects of the electron beam and implications of surface damage in the analysis of bone tissue.

Electron beam interactions with specimens in the scanning electron microscope (SEM) can lead to increased surface temperatures and damage. These changes may have significant consequences in the analysis of bone tissue. An investigation was performed to measure the surface temperature changes associated with the electron beam on a thermocouple with systematic variations in operating conditions. Probe currents, magnifications, and accelerating voltages were incrementally adjusted to measure the temperature changes and to make assessments for determining optimal operating conditions for the SEM in future analyses of bone tissue. Results from this study suggest that thermal effects were minimal at lower accelerating voltages (< 20 kV), lower probe currents (< 10 nA), and lower magnifications, but surface damage may still occur during the analysis of bone tissue.

Astrovirus diarrhea in Egyptian children.

This study describes the epidemiology of astrovirus diarrhea among a population-based cohort of 397 children aged <3 years residing in rural Egypt from 1995 to 1998. The age-specific incidence rates of astrovirus diarrheal episodes per person-year were 0.38 for infants aged <6 months, 0.40 for those aged 6-11 months, 0.16 for those aged 12-23 months, and 0.05 for those aged 24-35 months. The overall incidence rate of astrovirus diarrhea was the same as that of rotavirus diarrhea, 0.19 episodes per person-year. Astrovirus infection was pathogenic and associated with severe dehydration in 17% of the cases. The most frequent serotype was HAstV-1, and, in order of decreasing frequency, HAstV-5, HAstV-8 and HAstV-3, HAstV-6, HAstV-4, and HAstV-2. In determining whether astrovirus diarrhea was associated with a reduced incidence of subsequent disease, there was evidence to suggest HAstV-1 homotypic immunity but not heterotypic immunity. Because we observed 38% of the incidence of astrovirus diarrhea to occur in infants aged <6 months, a candidate astrovirus vaccine would have to confer immunity very early in life.

Selection of refractory and permissive strains of Aedes triseriatus (Diptera: Culicidae) for transovarial transmission of La Crosse virus.

The genetic basis of transovarial transmission of La Crosse virus in Aedes triseriatus (Say) was investigated through selection experiments on 2 mosquito strains. One strain was subject to selection for transovarial transmission refractoriness, the other for permissiveness to transovarial transmission. Response to selection for a low filial infection rate was rapid, decreasing from 18 to 3% in 3 generations. However, no response to selection for permissiveness was observed in the other strain; the average filial infection rates through 4 generations fluctuated between 25 and 40%. By contrast, the transovarial transmission rate in both strains showed a consistent response to selection in both directions. These patterns are consistent with a model in which transovarial transmission is controlled by a single genetic locus and permissiveness is conditioned by dominant alleles; whereas the filial infection rate is nongenetic and influenced by stochastic factors in the mosquito and virus.

Epidemiology of rotavirus diarrhea in Egyptian children and implications for disease control.

Reliable epidemiologic data are essential for formulating effective policy to control rotavirus disease through immunization. The objective of this study was to describe the epidemiology of rotavirus diarrhea in a population-based cohort of children under 3 years of age residing in Abu Homos, Egypt, in 1995-1996. Rotavirus diarrhea incidence rates (episodes per person-year) were 0.13 for infants aged <6 months, 0.61 for those aged 6-11 months, 0.17 for those aged 12-23 months, and 0.15 for those aged 24-35 months. Fifty-six percent of children with rotavirus diarrhea had clinical dehydration; 90% of rotavirus diarrheal episodes occurred between July and November. In infants under 1 year of age, receipt of breast milk was associated with a lower incidence of rotavirus diarrhea. No other sociodemographic or environmental factor was found to be significantly associated with rotavirus diarrhea. Of 46 rotavirus isolates with strains identified, 41 (89%) were G serotypes 1 and 2. Rotavirus diarrhea was a major cause of morbidity in this cohort. Promotion of breastfeeding may exert a protective effect in young infants in this setting, but improvements in water and sanitation are unlikely to be effective preventive measures. The use of effective immunization against rotavirus in early infancy should be considered a public health priority.

PIP: This study describes the epidemiology of rotavirus diarrhea in a population-based cohort of children under 3 years of age residing in Abu Homos, Egypt, during 1995-96. Samples consisted of a cohort of children under the age of 24 months assembled from two villages in the vicinity of Abu Homos. The age-specific incidence rates of rotavirus diarrheal episodes per person-year were 0.13 for infants aged 6 months, 0.61 for those aged 6-11 months, 0.17 for those aged 12-23 months, and 0.15 for those aged 24-35 months. No rotavirus diarrheal incidence occurred in infants under 20 weeks of age. The monthly incidence rates of rotavirus diarrhea demonstrate that 90% of the disease episodes occurred during the warmer months of July-November, with a peak incidence in August. In infants under 1 year of age, breast-feeding was associated with a lower incidence of rotavirus diarrhea. Promotion of breast-feeding may employ a protective effect in young infants in this setting, but improvements in water and sanitation are unlikely to be effective preventive measures.

Characterization of unusual G8 rotavirus strains isolated from Egyptian children.

We report the first detection of P[14], G8 rotaviruses isolated in Egypt from the stool of children participating in a 3 year study of rotavirus epidemiology. Two strains, EGY1850 and EGY2295, were characterized by a serotyping enzyme immunoassay (EIA), virus neutralization, and sequence analysis of the genes encoding VP7 and the VP8* portion of the VP4 gene. These two strains shared a high level of homology of their VP7s (87.8% nucleotide [nt], 97.2% amino acid [aa]) and VP4s (89.6% nt, 97.1% aa) and had the highest VP7 identity to serotype G8 (> 82% nt, > 92% aa) and VP4 identity to genotype P[14] (> or = 81% nt, > 91% aa) strains. Serological results with a VP7 G8-specific and VP4 P[14]-specific neutralizing monoclonal antibodies supported the genetic classification of EGY1850 and EGY2295 as P[14], G8. Genogroup analysis supports earlier findings that human G8 rotaviruses may be genetically related to bovine rotaviruses. These findings demonstrate that our understanding of the geographic distribution of rotavirus strains is incomplete, emphasize the need to monitor rotavirus serotypes, and extend the known distribution of serotype G8 and genotype P[14] strains in Africa.

Detection and characterization of novel rotavirus strains in the United States.

We recently established a rotavirus strain surveillance system in the United States to monitor the prevalent G serotypes before and after the anticipated implementation of a vaccination program against rotavirus and to identify the emergence of uncommon strains. In this study, we examined 348 rotavirus strains obtained in 1996 to 1997 from children with diarrhea in 10 U.S. cities. Strains were characterized for P and G types, subgroups, and electropherotypes by using a combination of monoclonal antibody immunoassay, reverse transcription-PCR, and hybridization. The four strains most commonly found worldwide comprised 83% of the isolates (P[8]G1, 66.4%; P[4]G2, 8.3%; P[8]G3, 6.9%; P[8]G4, 1.4%), but 9.2% were unusual strains (P[6]G9, 5.5%; P[8]G9, 1.7%; P[6]G1, 1.4%; and P[4]G1 and P[8]G2, 0. 3% each). Strains not typeable for P or G type accounted for 5.5% of the total, while 2.3% of the strains had more than one G type (mixed infections). All P[6]G9 strains tested had short electropherotypes and subgroup I specificity and were detected in 4 of 10 cities, while P[8]G9 strains had long electropherotypes and subgroup II VP6 antigens. Both sequence analysis of the VP7 open reading frame (about 94 to 95% amino acid identity with the VP7 gene of G9 prototype strain WI61) and binding to a G9-specific monoclonal antibody strongly suggest that U.S. G9 strains belong to serotype G9. The high detection rates of unusual rotaviruses with G9 (7.2%) or P[6] (6.9%) specificity in multiple U.S. cities suggest the emergence of new strains or inadequate diagnosis in the past. The epidemiologic importance of these strains remains to be determined.

Subclinical atherosclerosis in relation to hysterectomy status in black women.

BACKGROUND AND PURPOSE: This study was designed to investigate whether black women who underwent hysterectomy only (n = 59) or hysterectomy plus bilateral oophorectomy (n=25) were at increased risk of subclinical carotid atherosclerosis compared with black women who underwent natural menopause (n = 54). The effects of both surgery and menopausal status were evaluated. METHODS: Women aged 34 to 58 years were recruited from the Pittsburgh, Pa, area. Postmenopausal status was defined as a serum follicle-stimulating hormone level of >30 mIU/mL. Carotid duplex scans were performed to assess the degree of focal plaque. RESULTS: Among premenopausal women, focal plaque was present in 20% of nonhysterectomized versus 49% of hysterectomized-only women (P=.004). Among postmenopausal women, plaque was present in 69% of nonhysterectomized women, 86% of women with hysterectomy only, and 48% of women with oophorectomy and hysterectomy (P=.056). Among postmenopausal women, hormone replacement therapy was used by 23% of women who had undergone natural menopause, 0% of women with hysterectomy only, and 36% of women with oophorectomy and hysterectomy. The prevalence of plaque was 33% among hormone replacement therapy users versus 73% among nonusers (P=.014). In multivariate analysis, independent associations with the presence of at least 1 plaque were postmenopausal status and hysterectomy only. CONCLUSIONS: These data suggest that black women who undergo hysterectomy without oophorectomy may be at higher risk of subclinical carotid atherosclerosis than black women who undergo natural menopause or hysterectomy plus oophorectomy.

Determination of aryl hydrocarbon receptor nuclear translocator protein concentration and subcellular localization in hepatic and nonhepatic cell culture lines: development of quantitative Western blotting protocols for calculation of aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator protein in total cell lysates.

Western blot analysis was used to determine the concentration of the aryl hydrocarbon receptor nuclear translocator (ARNT) protein and aryl hydrocarbon receptor (AHR) in 11 mammalian cell culture lines derived from hepatic and nonhepatic tissues. The strategy was to first use Western blot analysis to determine the expression of ARNT or AHR in each cell line relative to its concentration in murine wild-type Hepa-1c1c7 (Hepa-1) cells. Actual ARNT and AHR concentrations in known amounts of total cell lysates were then determined by generating a standard curve with defined amounts of a highly purified ARNT or AHR protein and performing regression analysis. The results show that the level of ARNT expression in each of the cell lines is similar and represents approximately 0.001-0.002% of total cellular protein. The range of expression was only approximately 3-fold with wild-type Hepa-1 cells expressing the highest level of ARNT (33,000/cell) and canine kidney cells (MDCK line) expressing 14,000 ARNT molecules/cell. In contrast, the concentration of AHR varied by 65-fold over the different cell lines with the wild-type Hepa-1 expressing 323,000 AHR/cell and rat hepatoma cells (H4IIE) expressing 4700. The ratio of AHR to ARNT ranged from 0.3 in H4IIE cells to 10 in the Hepa-1 line with the majority of cells expressing 1-5 times more AHR than ARNT protein. Immunocytochemical staining of each cell line showed that ARNT was exclusively localized to the nuclear compartment and that a conserved nuclear localization signal mapped to the NH-terminal portion of the protein.

Marine stingers in far north Queensland.

Two box jellyfish in particular cause problems in tropical Queensland waters. Chironex fleckeri inhabit calm waters close to the shore between November and May. The venom includes three major components: haemolytic dermatonecrotic and myocardial. The dermatonecrotic toxin causes a ladder pattern of whiplash lesions to the skin which ulcerate become necrotic and heal very slowly over months: Neuromuscular paralysis and cardiovascular collapse may be fatal within minutes of envenomation. Emergency treatment comprises inactivation of stinging capsules by vinegar removal of tentacles analgesia, cardiopulmonary resuscitation and the administration of the specific antivenom. Carukia barnesi ('Irukandji') are found in both coastal and open waters. A patch of erythema with papules at the sting site is characteristically followed 30 min later by the onset of a catecholamine mediated syndrome. Headache and severe abdominal and back pain are usual and may be followed by hypertension, tachyarrhythmias and cardiogenic shock.

Studies on the differential sensitivity between diabetic and non-diabetic human erythrocytes to monoacetyl dapsone hydroxylamine-mediated methaemoglobin formation in vitro.

Methaemoglobin generation by monoacetyl dapsone hydroxylamine in non-diabetic and diabetic erythrocytes was investigated in vitro. Methaemoglobin formation in purified haemoglobin isolated from both types of erythrocytes as well as haemolysates from both diabetic and non-diabetic erythrocytes did not differ. Prior to 18 h incubation with 10 and 20 mM glucose diabetic erythrocytes were significantly less sensitive to monoacetyl dapsone-induced methaemoglobinaemia. After pre-incubation the differential was lost although significant change in glutathione concentrations could not be shown between the two cell types. NADH-diaphorase levels measured in diabetics and non-diabetics did not significantly differ. It is possible that diabetic cells display reduced hydroxylamine-mediated methaemoglobin generation due to differences in glutathione metabolism.

The structure of C5H 5RFe (+) (R = F, Cl, Br, I, O, OH, OCH3, C 6H 5, H) ions in the gas phase and the generation of their neutral counterparts by neutralization-reionization mass spectrometry.

The structure of C5H5FeR(+·) ions was studied by tandem mass spectromerry that included the neutralization-reionization (NR) method. Halogen-containing species (R = F, Cl, Br, I) showed fragmentation that was consistent with a structure that has the cyclopentadienyl ring and R as separate ligands at the metal atom (structure A). This structure also was identified for C5H5FeO(+) and CpFeOH(+·) ions, but these species also easily isomerized to metal-cyclopentadiene structure, RC5H5Fe(+·) (B), followed by hydrogen rearrangement(s) and CO loss. B was the dominant structure of C5H5FeH(+·) and C5H5FeC6H 5 (+·) ions. All ions that have structure A showed recovery signals in their NR mass spectra that indicated that their stable neutral counterparts were generated. The NR mass spectra also provided complementary information about the structure of ions before neutralization and after reionization.

A tandem mass spectrometric investigation of (C2H 5) 2X (+) ions (X = Cl, Br, I): The involvement of classical and nonclassical ethyl structures therein.

The formation of diethyl halonium ions (C2H5)2X(+) (X = Cl, Br, I) by a variety of ion-molecule reactions is described. The dissociation characteristics (metastable and collision-induced dissociation mass spectra) of these ions and their isomers were studied in detail. Some of the neutral fragmentation products were examined by their collision-induced dissociative ionization mass spectra.The participation of classical (1, CH3CH2X(+)CH2CH3) and nonclassical forms of the ions was considered. Dissociation reactions for which loss of positional identity of H-D atoms took place, for example C2H4 loss (a common fragmentation of metastable ions) and C2H5 (+) formation, were interpreted as involving nonclassical ions, 2. It was concluded that the ion-molecule reactions produced both ion structures, but in different halogen-dependent proportions. For (C2H5)2C1(+) ions, 2 is the major species, for (C2H5)2Br(+) both 1- and 2-type ions are generated, whereas for (C2H5)2I(+) the classical form 1 must be the predominant structure.

A tandem mass spectrometry study of the gas phase RSC6H 5Cr (+)L (R = H, C 6H 5; L = arene) and C 6H 5SSC 6H 5Cr (+) ions.

Ion-molecule reactions of chromium containing ions with arylsulfides have been studied in the gas phase and their products have been characterized by tandem mass spectrometry. C6H5SH and (C6H5)2S react as typical aromatic compounds and give rise to Cr(+)C6H5SR] and RC6H5Cr(+)QH5SR' [R = H, CH3, CH(CH3)2; R' = H, C6H5] ions. Metastable ion mass spectra of the latter species show that the metal is more strongly bound to diphenylsulfide than to alkylbenzenes. C6H5SSC6H5 reacts with chromium-containing ions to form only Cr(+)(C6H5SSC6H5). The decomposition characteristics of this ion and, in particular, the presence of a recovery signal in the neutralization-reionization mass spectrum are in keeping with the formation of a 1,2-dithia[2]cyclophane complex ion, which rearranges into a structurel(s) that contains Cr-S bond(s). No evidence was found for metal atom insertion into S-S, C-S, or S-H bonds.

Metastable ion study of substituted cyclopentadienylmanganese cations in the gas phase.

The behavior of some substituted cyclopentadienylmanganese ions has been studied by tandem mass spectrometry. This metastable ion study showed that only C5H5Mn(+) and (C5H4CN)Mn(+) ions retain their nido-cluster structure (1), which is characterized by a simple metal-ligand bond cleavage. Other substituted ions, RXC5H4Mn(+), rearrange to a different extent, depending on the nature of the substituent. The first rearrangement step is R radical migration to the central metal atom, leading to RMnC5H4X(+)-type ions (2). These ions decompose by elimination of X (for X=CO) or with formation of RMnX(+), but further rearrangements can also occur. These are the reverse migration of R from the metal atom to the π-ligand (for R=H, Ph) and cyclopentadienyl ring expansion (for X=CH2). Collisional activation mass spectra contained an Mn(+) ion peak, which can indicate the existence of stable type 1 structures for most cyclopentadienylmanganese ions. Carboxyl and hydroxymethyl derivatives exist, presumably as ions of type 2. The neutralization-reionization mass spectra of RXC5H4Mn(+) ions are also discussed.