The effects of 2-hydroxy-4-methylthio-butanoic acid supplementation on the rumen microbial population and duodenal flow of microbial nitrogen

Four multiparous, lactating Holstein cows (average DIM 169.5 ± 20.5 d), fitted with ruminal and duodenal cannulas, were used in a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments to investigate the effects of 2-hydroxy-4-methylthio-butanoic acid (HMTBA) when fed with diets differing in metabolizable protein (MP) supply and equal levels of crude protein on milk production and composition, rumen microbial activity, duodenal protein flow, and rumen bacterial community composition in vivo and in vitro. Experimental periods were 28 d in length. Cows were housed in individual tie stalls and were randomly assigned to 4 dietary treatments: low MP or high MP, supplemented with or without 25 g of HMTBA, which was top-dressed once daily at 0930 h. No interactions were observed between HMTBA and level of dietary MP, with the exception of ruminal acetate-to-propionate ratio. Milk yield was not affected by treatment and averaged 23.8 ± 2.06 kg/d. There was a tendency for increased milk protein percent in cows receiving low MP diets, averaging 3.30 ± 0.09% and 3.21 ± 0.09% for low MP and high MP, respectively. The total-tract apparent digestibility of organic matter, neutral detergent fiber, and nitrogen were greater in cows consuming the low MP diet. Rumen pH was lower in cows consuming high MP diets as well as in those consuming HMTBA. Rumen ammonia concentrations tended to be greater in cows consuming HMTBA, and volatile fatty acid concentrations were greater in cows consuming HMTBA. Duodenal dry matter flow, nitrogen flow, and microbial nitrogen flow did not differ between treatments. The bacterial community structure of cows receiving HMTBA was not affected at the phylum level. The relative abundance of bacterial phyla in vivo differed when compared with in vitro conditions for Firmicutes, Bacteroidetes, Proteobacteria, TM7, Tenericutes, Spirochaetes, SR1, and Verrucomicrobia.

Rumen bacterial communities can be acclimated faster to high concentrate diets than currently implemented feedlot programs

Aims

Recent studies have demonstrated RAMP^®, a complete starter feed, to have beneficial effects for animal performance. However, how RAMP may elicit such responses is unknown. To understand if RAMP adaptation results in changes in the rumen bacterial community that can potentially affect animal performance, we investigated the dynamics of rumen bacterial community composition in corn‐adapted and RAMP‐adapted cattle.

Methods and Results

During gradual acclimation of the rumen bacterial communities, we compared the bacterial community dynamics in corn and RAMP‐adapted using 16S rRNA gene amplicon sequencing. Significant shifts in bacterial populations across diets were identified. The shift in corn‐adapted animals occurred between adaptation step3 and step4, whereas in RAMP‐adapted cattle, the shift occurred between step2 and step3. As the adaptation program progressed, the abundance of OTUs associated with family Prevotellaceae and S24‐7 changed in corn‐adapted animals. In RAMP‐adapted animals, OTUs belonging to family Ruminococcaceae and Lachnospiraceae changed in abundance.

Conclusions

Rumen bacteria can be acclimated faster to high concentrate diets, such as RAMP, than traditional adaptation programs and the speed of bacterial community acclimation depends on substrate composition.

Significance and Impact of the Study

These findings may have implications for beef producers to reduce feedlot costs, as less time adapting animals would result in lower feed costs. However, animal feeding behavior patterns and other factors must be considered.

Amazonia through time: Andean uplift, climate change, landscape evolution, and biodiversity

The Amazonian rainforest is arguably the most species-rich terrestrial ecosystem in the world, yet the timing of the origin and evolutionary causes of this diversity are a matter of debate. We review the geologic and phylogenetic evidence from Amazonia and compare it with uplift records from the Andes. This uplift and its effect on regional climate fundamentally changed the Amazonian landscape by reconfiguring drainage patterns and creating a vast influx of sediments into the basin. On this "Andean" substrate, a region-wide edaphic mosaic developed that became extremely rich in species, particularly in Western Amazonia. We show that Andean uplift was crucial for the evolution of Amazonian landscapes and ecosystems, and that current biodiversity patterns are rooted deep in the pre-Quaternary.

The expression of caveolin-1 and the distribution of caveolae in the murine placenta and yolk sac: parallels to the human placenta

The expression pattern of caveolin-1 and the distribution of caveolae in the murine placental labyrinth and visceral yolk sac have been determined. Immunoblot analysis demonstrates that both placenta and yolk sac express the protein caveolin-1. Immunofluorescence microscopy was used to determine which cell types in the placental labyrinth and yolk sac express caveolin-1. In yolk sac, detectable caveolin-1 was restricted to endothelial cells and smooth muscle cells of the vitelline vasculature and to mesothelial cells. Endoderm, the major cell type in the yolk sac, does not express caveolin-1 as assessed by this assay. In the labyrinth region of the placenta, endothelial cells express caveolin-1 but this protein was not detectable in any of the three trophoblast layers. These tissues were also examined by electron microscopy to determine which cell types contain the specialized plasma membrane microdomains known as caveolae. Morphologically detectable caveolae were present in endothelial and smooth muscle cells, as well as mesothelial cells of the yolk sac and in endothelial cells of the placental labyrinth. Neither endodermal cells of the yolk sac nor trophoblastic cells in the placental labyrinth contained caveolae-like structures. We conclude that caveolin-1 and caveolae have restricted distribution in the murine placenta and yolk sac and that this parallels the situation in human placenta.

Drug-induced long QT syndrome: hERG K+ channel block and disruption of protein trafficking by fluoxetine and norfluoxetine

BACKGROUND AND PURPOSE

Fluoxetine (Prozac) is a widely prescribed drug in adults and children, and it has an active metabolite, norfluoxetine, with a prolonged elimination time. Although uncommon, Prozac causes QT interval prolongation and arrhythmias; a patient who took an overdose of Prozac exhibited a prolonged QT interval (QTc 625 msec). We looked for possible mechanisms underlying this clinical finding by analysing the effects of fluoxetine and norfluoxetine on ion channels in vitro.

EXPERIMENTAL APPROACH

We studied the effects of fluoxetine and norfluoxetine on the electrophysiology and cellular trafficking of hERG K+ and SCN5A Na+ channels heterologously expressed in HEK293 cells.

KEY RESULTS

Voltage clamp analyses employing square pulse or ventricular action potential waveform protocols showed that fluoxetine and norfluoxetine caused direct, concentration-dependent, block of hERG current (IhERG). Biochemical studies showed that both compounds also caused concentration-dependent reductions in the trafficking of hERG channel protein into the cell surface membrane. Fluoxetine had no effect on SCN5A channel or HEK293 cell endogenous current. Mutations in the hERG channel drug binding domain reduced fluoxetine block of IhERG but did not alter fluoxetine's effect on hERG channel protein trafficking.

CONCLUSIONS AND IMPLICATIONS

Our findings show that both fluoxetine and norfluoxetine at similar concentrations selectively reduce IhERG by two mechanisms, (1) direct channel block, and (2) indirectly by disrupting channel protein trafficking. These two effects are not mediated by a single drug binding site. Our findings add complexity to understanding the mechanisms that cause drug-induced long QT syndrome.

The dynamics of X-inactivation skewing as women age

Non-random X-chromosome inactivation (XCI) has been associated with X-linked diseases, neoplastic diseases, recurrent pregnancy loss, and trisomy risk. It also occurs more commonly in older female populations. To understand the etiology of non-random XCI and utilize this assay appropriately in clinical research and practice, the age-related alteration in XCI patterns in normal females needs to be clearly defined. In the present study, we evaluated the XCI status in 350 unselected women aged 0-88 years with unknown history of genetic disorders or abnormal pregnancies. DNA samples were extracted from peripheral blood and analyzed by a methylation-based assay at the androgen receptor locus. A weak but significant positive correlation was observed between age and degree of skewing in XCI over the whole age range (r = 0.23, p < 0.0001), and skewing values become non-normally distributed at older ages. However, the increase in skewed XCI appears to be more pronounced after age 30 than at younger ages. This trend supports the model of increased skewing with age as a consequence of hematopoietic stem cell senescence. An alternative possibility is that there is allele-specific loss of methylation with time that results in the appearance of increased XCI skewing using a methylation-based assay.

An empirical analysis of mt 16S rRNA covarion-like evolution in insects: site-specific rate variation is clustered and frequently detected

The structural and functional analysis of rRNA molecules has attracted considerable scientific interest. Empirical studies have demonstrated that sequence variation is not directly translated into modifications of rRNA secondary structure. Obviously, the maintenance of secondary structure and sequence variation are in part governed by different selection regimes. The nature of those selection regimes still remains quite elusive. The analysis of individual bacterial models cannot adequately explore this topic. Therefore, we used primary sequence data and secondary structures of a mitochondrial 16S rRNA fragment of 558 insect species from 15 monophyletic groups to study patterns of sequence variation, and variation of secondary structure. Using simulation studies to establish significance levels of change, we found that despite conservation of secondary structure, the location of sequence variation within the conserved rRNA structure changes significantly between groups of insects. Despite our conservative estimation procedure we found significant site-specific rate changes at 56 sites out of 184. Additionally, site-specific rate variation is somewhat clustered in certain helices. Both results confirm what has been predicted from an application of non-stationary maximum likelihood models to rRNA sequences. Clearly, constraints on sequence variation evolve and leave footprints in the form of evolutionary plasticity in rRNA sequences. Here, we show that a better understanding of the evolution of rRNA sequences can be obtained by integrating both phylogenetic and structural information.

Exposure-based death rates for child motor vehicle occupants

We used reports of additional occupants on trips from the Nationwide Personal Transportation Survey to estimate travel in cars and trucks for children age nine years and younger. For children age five to nine years these indirect estimates were 98% of directly reported travel. Using this travel data, the death rate was 4.0 per billion km of travel for children less than age one year and decreased to 1.7 for children age nine years. Infants have a higher exposure-based death rate for travel in cars and trucks than older children despite greater restraint use.

Pickup truck use in the National Personal Transportation Survey

To guide interventions to prevent injuries to pickup-truck occupants, we characterized pickup truck ownership, drivers and use in the 1995 National Personal Transportation Survey, which collects travel data from the civilian noninstitutionalized population of the US. SUDAAN software was used to account for the complex nature of the sample. Pickup truck ownership was more common in households with more vehicles, in rural households, in households living in single family homes and mobile homes, and in middle-income households. Among US regions, pickup truck ownership was highest among households in the mountain west. Pickup truck ownership was greater in households with two adults, whether or not children or youths were present, but this was largely due to the number of vehicles in these households. Driving a pickup on the sample day was more frequent among men, among drivers with less education and among full-time workers. A higher proportion of trips to work, work-related trips, longer trips and trips with fewer people were by pickup truck. Seat belt use was lower among pickup truck drivers than drivers of other vehicles. For only 0.5% of households (those with three or more members and a pickup truck as their only vehicle), restrictions on travel in cargo areas might be burdensome. Restrictions on cargo area travel, strengthening existing seat belt laws and social marketing strategies might increase the safety of pickup truck occupants.

Patterns of occurrence and 18S rDNA sequence variation of PKX (Tetracapsula bryosalmonae), the causative agent of salmonid proliferative kidney disease

Recent progress in understanding the etiology of proliferative kidney disease (PKD) includes the identification of freshwater bryozoans as the natural hosts of the myxozoan parasite that causes the disease in salmonid fish and formal description of the parasite as Tetracapsula bryosalmonae. This paper presents data on patterns of occurrence of T. bryosalmonae and sequence variation among isolates. T. bryosalmonae infects bryozoans that range from primitive to more derived genera within the Phylactolaemata and that differ in growth form and habits. Infected bryozoans have been collected in diverse habitats including cold, clear streams and warm, eutrophic lakes. Temporal surveys reveal intra- and interannual variation in infection levels, and spatial variation in incidence of infection is implicit by the apparent absence of T. bryosalmonae from many bryozoan populations. The significance of minor variation in partial sequences of 18S rDNA requires further investigation. The information presented here provides the first significant insights into the ecology of T. bryosalmonae.

Injury in children of low-income Mexican, Mexican American, and non-Hispanic white mothers in the USA: a focused ethnography

Several studies indicate that rates of serious pediatric injury are higher among Hispanics than among non-Hispanic whites in the USA. To investigate possible contributory factors, we interviewed 50 Mexican, 30 Mexican American, and 30 non-Hispanic white mothers in their own homes in the same low-income neighborhoods of Southern California. Mothers were identified via door-to-door canvassing in areas with high rates of pediatric injury. We observed household conditions and behaviors and obtained a detailed family history, including accounts of any occurrence of serious injury in a child under 5 years old, the highest-risk age group for pediatric injury. Results show that Mexican families were poorer, less educated, and lived in more hazardous and crowded conditions than did families in the other two groups. Nevertheless, they benefited from strong family bonds and a cultural tradition in which responsible older children typically supervise younger siblings. In contrast, a number of Mexican American and white mothers had been abused as children and were estranged from their own mothers; hence they lacked support and models of good parenting. There was much less self-reported smoking, drug use, and mental dysfunction among the Mexican mothers and their male partners as well as much less excessively active and/or aggressive behavior among their children. The nature of the injuries reported by the various groups seemed to reflect these differences. Appropriate interventions for each group are discussed. The study illustrates the importance of using ethnographic methods to examine the context of pediatric injury at the household level.

The Fc receptor for IgG expressed in the villus endothelium of human placenta is Fc gamma RIIb2

To evaluate the potential role of human placental endothelial cells in the transport of IgG from maternal to fetal circulation, we studied Fc gamma receptor (Fc gamma R) expression by immunohistology and immunoblotting. Several pan-Fc gamma RII Abs that label the placental endothelium displayed a distribution pattern that correlated well with transport functions, being intense in the terminal villus and nil in the cord. In contrast, the MHC class 1-like IgG transporter, FcRn, and the classical Fc gamma RIIa were not expressed in transport-related endothelium of the placenta. Our inference, that Fc gamma RIIb was the likely receptor, we confirmed by analyzing purified placental villi, enriched in endothelium, by immunoblotting with a new Ab specific for the cytoplasmic tail of Fc gamma RIIb. These experiments showed that the Fc gamma RII expressed in villus endothelium was the b2 isoform whose cytoplasmic tail is known to include a phosphotyrosyl-based motif that inhibits a variety of immune responses. We suggest that this receptor is perfectly positioned to transport IgG although as well it may scavenge immune complexes.

Localization of FCGR1 encoding Fcgamma receptor class I in primates: molecular evidence for two pericentric inversions during the evolution of human chromosome 1

The human high-affinity receptor for immunoglobulin G, FcgammaRI (FCGR1), is encoded by a family of three genes that share over 95% sequence homology. Curiously, the three genes in this recently duplicated gene family flank the centromere of human chromosome 1, with FCGR1B located at 1p12 and both FCGR1A and FCGR1C located at 1q21. We have previously speculated that a pericentric inversion could account for the separation of the genes in the FCGR1 family and explain their current chromosomal location. Here we present evidence, obtained through fluorescence in situ hybridization analysis, that in the rhesus monkey (Macaca mulatta) and baboon (Papio papio) FCGR1 is located adjacent to the centromere on the chromosomal arm with greatest homology to human 1p, whereas in the chimpanzee (Pan troglodytes) it is located adjacent to the centromere on the chromosomal arm with greatest homology to human 1q. The separation of the FCGR1 gene family in humans suggests that the location of a second pericentric inversion, known to distinguish the human from the chimpanzee chromosome 1, is within the FCGR1 gene family. This finding refines the assignment of homology between the human and chimpanzee chromosomes 1.

The adapter protein LAT enhances fcgamma receptor-mediated signal transduction in myeloid cells

FcgammaR clustering in monocytes initiates a cascade of signaling events that culminate in biological responses such as phagocytosis, production of inflammatory cytokines, and generation of reactive oxygen species. We have identified and determined the function of the adapter protein linker of activation of T cell (LAT) in FcgammaR-mediated signaling and function. Clustering of FcgammaRs on the human monocytic cell line, THP-1, induces phosphorylation of a major 36-kDa protein which immunoreacts with anti-LAT antisera. Our data indicate that although both the 36-kDa and 38-kDa isoforms of LAT are expressed in THP-1 and U937 human monocytic cells, FcgammaR clustering induces phosphorylation of the 36-kDa isoform only. Co-immunoprecipitation experiments revealed a constitutive association of p36 LAT with both FcgammaRI and FcgammaRIIa immunoprecipitates, and an activation-induced association of LAT with PLCgamma1, Grb2, and the p85 subunit of phosphatidylinositol 3-kinase. Transient transfection experiments in COS-7 cells indicated that overexpression of a wild type but not a dominant-negative LAT, that is incapable of binding to p85, enhances phagocytosis by FcgammaRI. Furthermore, bone marrow-derived macrophages from LAT-deficient mice displayed reduced phagocytic efficiency in comparison to the macrophages from wild-type mice. Thus, we conclude that p36 LAT serves to enhance FcgammaR-induced signal transduction in myeloid cells.

Fatalities to occupants of cargo areas of pickup trucks

We sought to describe the fatalities to occupants of pickup truck cargo areas and to compare the mortality of cargo area occupants to passengers in the cab. From the Fatality Analysis Reporting System (FARS) files for 1987-1996, we identified occupants of pickup trucks with at least one fatality and at least one passenger in the cargo area. Outcomes of cargo area occupants and passengers in the cab were compared using estimating equations conditional on the crash and vehicle. Thirty-four percent of deaths to cargo occupants were in noncrash events without vehicle deformation. Fifty-five percent of those who died were age 15-29 years and 79% were male. The fatality risk ratio (FRR) comparing cargo area occupants to front seat occupants was 3.0 (95% Confidence Interval [CI] = 2.7-3.4). The risk was 7.9 (95% CI = 6.2-10.1) times that of restrained front seat occupants. The FRR ranged from 92 (95% CI = 47-179) in noncrash events to 1.7 (95% CI = 1.5-1.9) in crashes with severe vehicle deformation. The FRR was 1.8 (95% CI = 1.4-2.3) for occupants of enclosed cargo areas and 3.5 (95% CI = 3.1-4.0) for occupants of open cargo areas. We conclude that passengers in cargo areas of pickup trucks have a higher risk of death than front seat occupants, especially in noncrash events, and that camper shells offer only limited protection for cargo area occupants.

Childhood sexual abuse history and role reversal in parenting

OBJECTIVE

This study explored the main and interactive effects of sexual abuse history and relationship satisfaction on self-reported parenting, controlling for histories of physical abuse and parental alcoholism.

METHOD

The community sample consisted of 90 mothers of 5- to 8-year-old children. The sample was limited to those mothers currently in an intimate relationship, 19 of whom reported a history of childhood sexual abuse. Participants completed the Child Behavior Checklist, the Parenting Stress Inventory, the Family Cohesion Index, and questions assessing parent-child role reversal, history of abuse and parental alcoholism, and current relationship satisfaction.

RESULTS

Results of analyses and multivariate analyses of covariance suggested that sexual abuse survivors with an unsatisfactory intimate relationship were more likely than either sexual abuse survivors with a satisfactory relationship or nonabused women to endorse items on a questionnaire of role reversal (defined as emotional overdependence upon one's child). Role reversal was not significantly predicted by histories of physical abuse or parental alcoholism or child's gender. While parenting stress was inversely predicted by the significant main effect of relationship satisfaction, neither parenting stress nor child behavior problems were predicted by the main effect of sexual abuse history or by the interaction between sexual abuse history and relationship satisfaction.

CONCLUSIONS

These results suggest the unique relevance of sexual abuse history and relationship satisfaction in the prediction of a specific type of parent-child role reversal--namely, a mother's emotional overdependence upon her child.

A phylogeny of the damselfly genus calopteryx (Odonata) using mitochondrial 16S rDNA markers

We seek to reconstruct the phylogenetic relationships of the damselfly genus Calopteryx, for which extensive behavioral and morphological knowledge already exists. To date, analyses of the evolutionary pathways of different life history traits have been hampered by the absence of a robust phylogeny based on morphological data. In this study, we concentrate on establishing phylogenetic information from parts of the 16S rDNA gene, which we sequenced for nine Calopteryx species and five outgroup species. The mt 16S rDNA data set did not show signs of saturated variation for ingroup taxa, and phylogenetic reconstructions were insensitive to variation of outgroup taxa. Parsimony, neighbor-joining, and maximum-likelihood reconstructions agreed on parts of the tree. A consensus tree summarizes the significant results and indicates problematic nodes. The 16S rDNA sequences support monophyly of the genera Mnais, Matrona, and Calopteryx. However, the genus Calopteryx may not be monophyletic, since Matrona basilaris and Calopteryx atrata are sister taxa under every parameter setting. The North American and European taxa each appear as monophyletic clades, while the Asian Calopteryx atrata and Calopteryx cornelia are not monophyletic. Our data implies a different paleobiogeographic history of the Eurasian and North American species, with extant Eurasian species complexes shaped by glacial periods, in contrast to extant North American species groups.

Zinc has no effect on IL-3-mediated apoptosis of BAF-3 cells but enhances CD95-mediated apoptosis of jurkat cells

The feasibility of using a zinc-inducible gene expression system for the study of apoptosis-controlling genes in BAF-3 murine B cells and Jurkat human T cells was evaluated. Initially, cell sensitivity to a range of zinc concentrations was examined. It was found that zinc concentrations above 60 microM were toxic to BAF-3 cells and those above 50 microM were toxic to Jurkat cells. Secondly, the zinc concentration required to achieve maximal gene expression was examined. BAF-3 cells transiently transfected with the pMTCB6+/luciferase vector were exposed to zinc concentrations ranging from 0-120 microM, whilst stably transfected Jurkat cells were exposed to 0-70 microM zinc. At zinc concentrations nontoxic to each cell type, the maximum induction achieved was 20-fold (at 60 microM) in BAF-3 cells, and 7.5-fold (at 50 microM) in Jurkat cells. Thirdly, the effect of zinc on apoptosis was examined. It was shown that exposure to nontoxic zinc concentrations had no effect on IL-3 withdrawal-mediated apoptosis of BAF-3 cells. However, in the case of Jurkat cells, pre-exposure to zinc augmented CD95-mediated apoptosis. These results illustrate the importance of characterizing individual cell lines when using zinc-inducible gene expression systems.

Analysis of fatalities in extended cab pickup trucks using an estimating equation method

We compared the fatality risk for occupants of rear passenger seats in extended cab and crew cab pickup trucks to the fatality risk for front seat occupants of the same vehicles using the (US) Fatality Analysis Reporting System (FARS) for 1982-1997. A 10-digit truncated vehicle identification number was used to classify the pickup trucks. The data were analyzed with an estimating equation for data having few observations per stratum. We identified 549 extended cab pickup trucks with one or more occupants of rear passenger seats and one or more occupant deaths. Occupants of rear passenger seats had a fatality risk 43% lower than front seat occupants (95% confidence interval 32% to 52%), controlling for age, sex, and restraint use. Occupants of rear seats of extended cabs in compact pickup trucks did not experience any higher fatality risk (relative to front-seat occupants of the same vehicles) than rear seat occupants of extended cabs in full-size pickup trucks and large 4-door crew cabs.

Physiological determinants of performance on an indoor military obstacle course test

Obstacle courses (OCs), physical challenge courses, and confidence courses are valuable in training and assessing military troops. However, OCs are not well characterized with regard to physical demands and requisite abilities. The purpose of this study was to evaluate the physical capabilities associated with success on an OC. Male subjects (N = 47) were assessed on an OC, skinfolds, upper and lower body aerobic and anaerobic power, muscular strength, and endurance. Faster performers were lighter (p < 0.003), leaner, and, relative to body weight, averaged greater arm anaerobic peak and mean power, leg aerobic power, one-repetition maximum leg press, and one-repetition maximum latissimus dorsi pull-down, than slower performers. There were significant correlations between OC time and weight (0.59), percent fat (0.54), anaerobic leg mean power (-0.43), arm anaerobic peak (-0.48) and mean power (-0.48), and arm (-0.51) and leg aerobic power (-0.53), all expressed relative to body weight. A three-variable regression model accounted for 35% of the variation in OC time. Good performers on this OC displayed many diverse physical capabilities.

Molecular data implicate bryozoans as hosts for PKX (phylum Myxozoa) and identify a clade of bryozoan parasites within the Myxozoa

Proliferative kidney disease (PKD), a condition associated with high mortality in salmonid fish, represents an abnormal immune response to the presence of an enigmatic myxozoan, which has been designated simply as PKX organism because its generic and specific status are obscure. Phylogenetic analyses of partial sequences of the 18S rDNA of PKX and of myxozoan parasites infecting the bryozoans Cristatella mucedo, Pectinatella magnifica and Plumatella rugosa, including the previously named Tetracapsula bryozoides from C. mucedo, showed that these taxa represent a distinct clade that diverged early in the evolution of the Myxozoa before the radiation of the other known myxozoan genera. A common feature of the myxozoans in this clade may be the electron-dense sporoplasmosomes with a lucent bar-like structure, which occur in T. bryozoides and PKX but not in the myxozoans belonging to the established orders Bivalvulida and Multivalvulida. Variation of 0.5-1.1% was found among the PKX 18S rDNA sequences obtained from fish from North America and Europe. The 18S rDNA sequence for T. bryozoides showed that it is a distinct taxon, not closely related to PKX but some sequences from myxozoans infecting 2 of the bryozoan species were so similar to those of PKX as to be indistinguishable. Other sequences from the new myxozoans in bryozoans at first appeared distinct from PKX in a maximum likelihood tree but, when analysed further, were also found to be phylogenetically indistinguishable from PKX. We propose that at least some variants of these new myxozoans from bryozoans are able to infect and multiply in salmonid fish, in which they stimulate the immune reaction and cause PKD but are unable to form mature spores to complete their development.

Ultrastructure of Myxidium trachinorum sp. nov. from the gallbladder of the lesser weever fish Echiichthys vipera

Myxidium trachinorum sp. nov. is described from the gallbladder of the lesser weever fish Echiichthys vipera. Pseudoplasmodia attach themselves to the gallbladder epithelium by filose processes, which are inserted between host cells. Pseudoplasmodia undergo endogenous cell formation at the secondary and tertiary levels. In the proliferative cycle, primary and endogenous cells are packed with digestive vacuoles formed by phagocytosis. In the sporogonic cycle the pseudoplasmodium becomes a pericyte enclosing two secondary cells (lacking digestive vacuoles) in a vacuole. These give rise to five cells each two valvogenic, two capsulogenic and a binucleate sporoplasm, which mature into spores. Comparison of the disporic M. trachinorum with polysporic species of Myxidium revealed significant differences in plasmodial ultrastructure, especially their attachments to host cells, surface characteristics and mode of nutrition, and in formation of generative cells. These suggest that the genus Myxidium may require revision.

Polymorphic X-chromosome inactivation of the human TIMP1 gene

X inactivation silences most but not all of the genes on one of the two X chromosomes in mammalian females. The human X chromosome preserves its activation status when isolated in rodent/human somatic-cell hybrids, and hybrids retaining either the active or inactive X chromosome have been used to assess the inactivation status of many X-linked genes. Surprisingly, the X-linked gene for human tissue inhibitor of metalloproteinases (TIMP1) is expressed in some but not all inactive X-containing somatic-cell hybrids, suggesting that this gene is either prone to reactivation or variable in its inactivation. Since many genes that escape X inactivation are clustered, we examined the expression of four genes (ARAF1, ELK1, ZNF41, and ZNF157) within approximately 100 kb of TIMP1. All four genes were expressed only from the active X chromosome, demonstrating that the factors allowing TIMP1 expression from the inactive X chromosome are specific to the TIMP1 gene. To determine if this variable inactivation of TIMP1 is a function of the hybrid-cell environment or also is observed in human cells, we developed an allele-specific assay to assess TIMP1 expression in human females. Expression of two alleles was detected in some female cells with previously demonstrated extreme skewing of X inactivation, indicating TIMP1 expression from the inactive chromosome. However, in other cells, no expression of TIMP1 was observed from the inactive X chromosome, suggesting that TIMP1 inactivation is polymorphic in human females.

Household poisoning exposure among children of Mexican-born mothers: an ethnographic study

OBJECTIVE

To explore reasons for high rates of unintentional poisoning among Latino children under 5 years old.

DESIGN

Ethnographic interviews were carried out using a sample of mothers identified via door-to-door canvassing in an area with documented high injury rates among Latino children. Interviews included many open-ended and follow-up questions to elicit a detailed family history and emphasized observation of conditions and behaviors in the homes.

SETTING

Low-income neighborhoods of Southern California.

SUBJECTS

Fifty mothers born in Mexico with children under 5 years old.

RESULTS

Children were exposed to potential poisoning agents in more than 80% of homes. Contributory factors related to culture included favorable attitudes toward iron as a healthful substance; extensive use of products that lack child-resistant packaging, such as rubbing alcohol and medicines from Mexico; high prevalence of shared housing; limited familiarity with toxic household chemicals not widely used in Mexico; and inability to read warning labels in English.

CONCLUSION

Current Poison Control Center outreach efforts should be expanded. Clinicians are uniquely positioned to advise parents about the safe use and storage of toxic substances, including widely used products lacking child-resistant packaging. Medicines should be labeled in Spanish for those who do not know English.

The SH2-containing 5'-inositol phosphatase (SHIP) is tyrosine phosphorylated after Fc gamma receptor clustering in monocytes

Current models of Fc gamma R signal transduction in monocytes describe a molecular cascade that begins upon clustering of Fc gamma R with the phosphorylation of critical tyrosine residues in the cytoplasmic domains of Fc gamma RIIa or the gamma-chain subunit of Fc gamma RI and Fc gamma RIIIa. The cascade engages several other tyrosine-phosphorylated molecules, either enzymes or adapters, to manifest ultimately an array of biological responses, including phagocytosis, cell killing, secretion of a variety of inflammatory mediators, and activation. Continuing to assess systematically the molecules participating in the cascade, we have found that the SH2-containing 5'-inositol phosphatase (SHIP) is phosphorylated on tyrosine early and transiently after Fc gamma R clustering. This molecule in other systems, such as B cells and mast cells, mediates an inhibitory signal. We find that clustering of either Fc gamma RIIa or Fc gamma RI is effective in inducing SHIP phosphorylation, that SHIP binds in vitro to a phosphorylated immunoreceptor tyrosine-based activation motif, peptide from the cytoplasmic domain of Fc gamma RIIa in activation-independent fashion, although SHIP binding increases upon cell activation, and that Fc gamma RIIb and Fc gamma RIIc are not responsible for the observed SHIP phosphorylation. These findings prompt us to propose that SHIP inhibits Fc gamma R-mediated signal transduction by engaging immunoreceptor tyrosine-based activation motif-containing cytoplasmic domains of Fc gamma RIIa and Fc gamma RI-associated gamma-chain.

Protein interactions of Src homology 2 (SH2) domain-containing inositol phosphatase (SHIP): association with Shc displaces SHIP from FcgammaRIIb in B cells

Our recent studies revealed that the inositol phosphatase Src homology 2 (SH2) domain-containing inositol phosphatase (SHIP) is phosphorylated and associated with Shc exclusively under negative signaling conditions in B cells, which is due to recruitment of the SHIP SH2 domain to the FcgammaRIIb. In addition, we reported that SHIP-Shc interaction involves both SHIP SH2 and Shc phosphotyrosine binding domains. These findings reveal a paradox in which the single SH2 domain of SHIP is simultaneously engaged to two different proteins: Shc and FcgammaRIIb. To resolve this paradox, we examined the protein interactions of SHIP. Our results demonstrated that isolated FcgammaRIIb contains SHIP but not Shc; likewise, Shc isolates contain SHIP but not FcgammaRIIb. In contrast, SHIP isolates contain both proteins, revealing two separate pools of SHIP: one bound to FcgammaRIIb and one bound to Shc. Kinetic studies reveal rapid SHIP association with FcgammaRIIb but slower and more transient association with Shc. Affinity measurements using a recombinant SHIP SH2 domain and phosphopeptides derived from FcgammaRIIb (corresponding to Y273) and Shc (corresponding to Y317) revealed an approximately equal rate of binding but a 10-fold faster dissociation rate for FcgammaRIIb compared with Shc phosphopeptide and yielding in an affinity of 2.1 microM for FcgammaRIIb and 0.26 microM for Shc. These findings are consistent with a model in which SHIP transiently associates with FcgammaRIIb to promote SHIP phosphorylation, whereupon SHIP binds to Shc and dissociates from FcgammaRIIb.

Differences between pickup truck and automobile driver-owners

This study compares pickup truck driver-owners and drivers who owned only automobiles with respect to demographic factors, conditions of use, risk-taking driving behavior, prior driving history and attitudes towards motor vehicle laws. A telephone survey conducted in Riverside County, CA determined that 36% of the households had a pickup truck. Pickup truck owners were primarily male, aged 30-39 years, married, reported lower restraint use and more risky driving behaviors, and had more traffic citations. Differences in behaviors and attitudes were largely a function of age and gender. There is a need to design appropriate occupant safety interventions for those most likely to own pickup trucks.

Molecular characterization of six variant Fcgamma receptor class I (CD64) transcripts

In humans, three distinct but closely related classes of receptors that bind the Fc portion of IgG (FcgammaRI, II and III) have been identified. FcgammaRI can bind monomeric IgG with high affinity and has a unique third extracellular domain (EC3). Three very similar genes have been characterized for FcgammaRI (A, B, C). Although the sequences are remarkably similar, a number of coding-region differences discriminate between the genes and amongst their transcripts. Six distinct FcgammaRI transcripts were analysed. Three transcripts, one from each gene, contain all six exons. Only the gene A transcript appears to encode a bona fide high affinity receptor, a three Ig-domain membrane spanning receptor that can bind monomeric IgG. Stop codons in the EC3 domains of the gene B and gene C isoforms would be predicted to generate secreted receptors. Three transcripts are alternatively spliced isoforms, one from gene A and two from gene B. One gene B transcript encodes a two Ig-domain transmembrane receptor which has structural characteristics of a low affinity FcgammaR.

Chimeric receptors composed of phosphoinositide 3-kinase domains and FCgamma receptor ligand-binding domains mediate phagocytosis in COS fibroblasts

Receptors for the Fc portion of IgG (FcgammaR) initiate phagocytosis of IgG-opsonized particles by a process involving the assembly of a multi-molecular signaling complex. Several members of this complex have been identified, including Src family kinases, Syk/ZAP 70 family kinases, and phosphoinositide 3-kinase (PI3-K). To test directly the role of PI3-K in mediating phagocytosis, we assessed the phagocytic ability of chimeric receptors composed of FcgammaR extracellular and transmembrane domains fused to regions of the p85 subunit of PI3-K. We found that chimeric receptors with cytoplasmic tails composed of the entire p85 subunit of PI3-K or the inter-Src homology 2 portion of p85 triggered phagocytosis in transfected COS fibroblasts. These two chimeras also showed phosphoinositide kinase activity in vitro when immunoadsorbed. In contrast, a chimera containing only the carboxyl-terminal Src homology 2 domain of p85 that does not interact with the catalytic p110 subunit of PI3-K did not trigger phagocytosis, nor did it show kinase activity in vitro. These data suggest that localization and direct activation of PI3-K at the site of particle attachment is sufficient to trigger the process of phagocytosis.

Family, social, and cultural factors in pedestrian injuries among Hispanic children

OBJECTIVES

In an earlier population based surveillance study of pediatric injuries, the rate of Hispanic children injured as pedestrians was 63/100,000 compared with 17/100,000 for non-Hispanic white children. The present study was designed to examine the effect of family, social, and cultural factors on the rate of pedestrian injury in a population of Hispanic children in the southwestern US.

METHODS

A case-control study of pedestrian injuries among Hispanic children. The sample consisted of 98 children 0-14 years of age hospitalized as a result of a pedestrian injury and 144 randomly selected neighborhood controls matched to the case by city, age, gender, and ethnicity. Cases were compared with controls using conditional logistic regression; in the study design the odds ratio (OR) estimates the incidence rate ratio.

RESULTS

The following family and cultural variables were associated with an increased risk of injury: household crowding (OR = 2.8, 95% confidence interval (CI) 1.1 to 7.1 for 1.01-1.5 persons per room, compared with < or = 1.0 persons per room), one or more family moves within the past year (OR 2.2, 95% CI 1.2 to 4.1), poverty (OR 1.9, 95% CI 1.1 to 3.3), and inability of mother (OR 3.6, 95% CI 1.3 to 10) or father (OR 5.6, 95% CI 1.5 to 20) to read well. However, children in single parent households and children whose parents did not drive a car, had less education, or were of rural origin, did not have an increased rate of injury.

CONCLUSIONS

These results have implications for childhood pedestrian prevention efforts for low income, non-English speaking Hispanic populations, and perhaps for other immigrant and high risk groups. Prevention programs and materials need to be not only culturally sensitive but also designed for those with limited reading skills. In addition, environmental interventions that provide more pedestrian friendly neighborhoods must be considered.

Factors associated with restraint use of children in fatal crashes

OBJECTIVE

This study was designed to characterize the restraint use of children in fatal crashes and to determine factors that were related to child restraint use.

METHODS

Crashes in which a vehicle occupant died were selected from the 1994 Fatal Analysis Reporting System data. Restraint use of children (0-9 years) in these crashes was characterized and examined in relation to vehicle and driver characteristics.

RESULTS

Restraint use declined with increasing age of children and increasing number of occupants. Restraint use was also lower in older vehicles, in pickups and large vans, between 3 AM and 6 AM, and in rural areas. Driver characteristics associated with lower restraint use of child passengers included unrestrained drivers, younger drivers, and alcohol use at the time of crash. Driver restraint use was the strongest predictor of child restraint use. Differences in restraint use by age of the child, number of occupants, time, urban/rural area, and driver restraint use persisted in a logistic model.

CONCLUSION

Restraint use in crashes is substantially lower than that in observational studies, suggesting that these studies are not reflective of high-risk conditions for crashes in which children are involved. Child occupant protection counseling must stress restraint use under all conditions of travel. Local, state, and national efforts must be aimed at increasing family occupant protection for the entire family.

Demographic risk factors for injury among Hispanic and non-Hispanic white children: an ecologic analysis

OBJECTIVES

To determine the effects of neighborhood levels of poverty, household crowding, and acculturation on the rate of injury to Hispanic and non-Hispanic white children.

SETTING

Orange County, California.

METHODS

An ecologic study design was used with census block groups as the unit of analysis. Measures of neighborhood poverty, household crowding, and acculturation were specific to each ethnic group. Poisson regression was used to calculate mutually adjusted incidence rate ratios (IRRs) corresponding to a 20% difference in census variables.

RESULTS

Among non-Hispanic white children, injury rates were more closely associated with neighborhood levels of household crowding (adjusted IRR 2.36, 95% confidence interval (CI) 1.22 to 4.57) than with neighborhood poverty (adjusted IRR 1.06, 95% CI 0.89 to 1.26). For Hispanic children, the strongest risk factors were the proportion of Hispanic adults who spoke only some English (compared with the proportion who spoke little or no English, adjusted IRR 1.26, 95% CI 1.04 to 1.53) and the proportion who were US residents for < 5 years (adjusted IRR 1.20, 95% CI 1.001 to 1.43). Neighborhood levels of household crowding were not related to injury among Hispanic children (adjusted IRR 0.98, 95% CI 0.89 to 1.08), but surprisingly, neighborhood poverty was associated with lower injury rates (adjusted IRR 0.89, 95% CI 0.81 to 0.97).

CONCLUSIONS

Cultural and geographic transitions, as well as socioeconomic differences, appear to contribute to differences in childhood injury rates between ethnic groups.

Functional separation of pseudopod extension and particle internalization during Fc gamma receptor-mediated phagocytosis

Receptors for the Fc portion of immunoglobulin (Ig)G (Fc gamma R) mediate phagocytosis of IgG-opsonized particles by a process that can be divided into four major steps: receptor-ligand binding, pseudopod extension, internalization, and lysosomal fusion. We have expressed single classes of Fc gamma R in COS fibroblasts to examine the structural determinants necessary to complete the four steps of phagocytosis. Using phase contrast, fluorescence, confocal, and electron microscopy we have demonstrated that Fc gamma R-expressing COS cells can phagocytose in a manner similar to that of professional phagocytes. We have further analyzed the capacity of the three classes of Fc gamma R to phagocytose, placing special emphasis on the Fc gamma RIA-gamma chain complex, which allowed us to examine independently the roles of the ligand-binding unit (Fc gamma RIA) and the signaling unit (gamma chain). We found that receptor complexes containing a conserved tyrosine activation motif (ITAM), as found in the cytoplasmic domain of Fc gamma RIIA and in the gamma chain associated with Fc gamma RIA and Fc gamma RIIIA, readily internalized target particles. In contrast, Fc gamma RIA alone, having no ITAM, was unable to internalize target particles efficiently, but did mediate pseudopod extension. Cotransfection of gamma chain with Fc gamma RIA restored the ability of the receptor to internalize target particles. A mutant Fc gamma RIA in which the cytoplasmic domain had been deleted was also capable of mediating pseudopod extension, showing that neither the gamma chain nor the cytoplasmic domain of Fc gamma RIA were required for this step. Cytochalasin D, an inhibitor of actin polymerization, blocked particle internalization by all Fc gamma R, but did not block pseudopod extension. Staining the Fc gamma RIA COS cells for F-actin and for tyrosine phosphoproteins, we found that actin did not polymerize during Fc gamma RIA-mediated pseudopod extension, nor were tyrosine kinases activated. Our data suggest that pseudopod extension and internalization are functionally distinct steps mediated through different pathways.

Adult attachment and long-term effects in survivors of incest

OBJECTIVE

The aim of the study was to test the hypothesis that adult attachment is related to distress and personality disorders in incest survivors.

METHOD

Adult female incest survivors recruited from the community participated in a structured interview (Family Attachment Interview; Bartholomew & Horowitz, 1991) and completed measures of current functioning (Impact of Event Scale, SCL-10, Beck Depression Inventory) and personality (MCMI-II). Complete data from 92 cases out of the total sample of 112 were analyzed.

RESULTS

Analyses of variance suggested that attachment (as represented by a category) was significantly related to personality structure, with fearful individuals showing more avoidant, self-defeating, and borderline tendencies and preoccupied individuals showing more dependent, self-defeating, and borderline tendencies than secure or dismissing individuals. Results of hierarchical regression analyses suggested that attachment (as represented by four dimensions) was significantly associated with personality structure, depression and distress, and abuse severity with post traumatic stress disorder (PTSD) symptoms (intrusive thoughts and avoidance of memories) and depression.

CONCLUSIONS

The findings demonstrated the propensity for insecure attachment among incest survivors. Sexual abuse severity and attachment have significant but distinct effects on longterm outcome; abuse characteristics predict classic PTSD symptoms and attachment insecurity predicts distress, depression, and personality disorders above and beyond any effects of abuse severity.