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161.
I examine the provision of mental health services to Medicaid recipients in New Mexico to illustrate how managed care accountability models subvert the allocation of responsibility for delivering, monitoring, and improving care for the poor. The downward transfer of responsibility is a phenomenon emergent in this hierarchically organized system. I offer three examples to clarify the implications of accountability discourse. First, I problematize the public-private "partnership" between the state and its managed care contractors to illuminate the complexities of exacting state oversight in a medically underserved, rural setting. Second, I discuss the strategic deployment of accountability discourse by members of this partnership to limit use of expensive services by Medicaid recipients. Third, I focus on transportation for Medicaid recipients to show how market triumphalism drives patient care decisions. Providers and patients with the least amount of formal authority and power are typically blamed for system deficiencies.  相似文献   
162.
Oral efficacy of an attenuated rabies virus vaccine in skunks and raccoons   总被引:2,自引:0,他引:2  
Raccoons and skunks are major rabies reservoirs in North America. Oral vaccination is one method to consider for disease control in these carnivores. Under field conditions in the USA, only one oral rabies vaccine has been used. It is efficacious in wildlife such as raccoons (Procyon lotor), coyotes (Canis latrans), and foxes (Vulpes vulpes) but not in skunks (Mephitis mephitis). The objectives of this study were to evaluate an attenuated SAG-2 rabies virus vaccine for safety, immunogenicity, and efficacy by the oral route in skunks and raccoons. Two of five skunks and three of five raccoons developed virus neutralizing antibodies (VNA) by day 14 following oral administration of SAG-2 vaccine. All animals remained healthy. Upon challenge, naive controls succumbed to rabies. Among vaccinated animals, four of five skunks and all five raccoons had VNA on day 7 post-challenge and all survived. Given these results, SAG-2 is a promising candidate vaccine that may satisfy both safety and efficacy concerns for oral rabies immunization of major North American rabies reservoirs.  相似文献   
163.

Background

Collective neural crest cell migration is critical to the form and function of the vertebrate face and neck, distributing bone, cartilage, and nerve cells into peripheral targets that are intimately linked with head vasculature. The vasculature and neural crest structures are ultimately linked, but when and how these patterns develop in the early embryo are not well understood.

Results

Using in vivo imaging and sophisticated cell behavior analyses, we show that quail cranial neural crest and endothelial cells share common migratory paths, sort out in a dynamic multistep process, and display multiple types of motion. To better understand the underlying molecular signals, we examined the role of angiopoietin 2 (Ang2), which we found expressed in migrating cranial neural crest cells. Overexpression of Ang2 causes neural crest cells to be more exploratory as displayed by invasion of off-target locations, the widening of migratory streams into prohibitive zones, and differences in cell motility type. The enhanced exploratory phenotype correlates with increased phosphorylated focal adhesion kinase activity in migrating neural crest cells. In contrast, loss of Ang2 function reduces neural crest cell exploration. In both gain and loss of function of Ang2, we found disruptions to the timing and interplay between cranial neural crest and endothelial cells.

Conclusions

Together, these data demonstrate a role for Ang2 in maintaining collective cranial neural crest cell migration and suggest interdependence with endothelial cell migration during vertebrate head patterning.
  相似文献   
164.
Summary Chinese hamster ovary (CHO) cells are treated with hydroxurea followed by a caffeine treatment to form detached kinetochore fragments in the absence of sister chromatids. Detached kinetochores in mitotic CHO cells display a functional association with MTs initiated from one or both centrosomes such that these association(s) have a significant influence on the location and orientation of detached kinetochores and/or their fragments. Kinetochore fragments which are amphitelically oriented are positioned approximately midway between the two centrosomes. Thus, a kinetochore isolated from a single chromatid can capture MTs from both poles. Monotelic orientation of these fragments is more frequently observed with kinetochore fragments located an average distance of 2.5 m from the nearest centrosome, compared to an average distance of 4.4 m in amphitelically oriented fragments. In cells treated with the potent MT poison, nocodazole, kinetochore isolation also occurs and therefore is not dependent on the presence of MTs. CHO cells treated to produce isolated kinetochores or kinetochore fragments then subsequently hyperosmotically shocked show no MTs directly inserted into kinetochore lamina, similar to the response of sucrose-treated metapbase PtK1 cells. This treatment shows circular kinetochores tangentially associated with bundles of MTs that are located an average of 1.5 m from the centrosome. Our results suggest that a single kinetochore fragment can attach to MTs initiated from one or both centrosomes and that their specific association to MT fibers defines orientation of detached kinetochores within the spindle domain.  相似文献   
165.
Abstract: Slices of hippocampal area CA1 were used to test inhibitors of arachidonic acid metabolism for their effects on glutamate/aspartate release from the CA3-derived Schaffer collateral, commissural, and ipsilateral associational terminals. Test compounds [3 µ M nordihydroguaiaretic acid (NDGA) and 1 µ M 3-[3-(4-chlorobenzyl)-3- tert -butylthio-5-isopropylindol-2-yl]-2,2-dimethyl-propanoic acid (MK-886)] that reduced the production and release of 5-lipoxygenase metabolites also selectively reduced the K+-evoked release of aspartate. In contrast, the cyclooxygenase inhibitor indomethacin (100 µ M ) selectively enhanced the release of glutamate. At a concentration (100 µ M ) that nonselectively depressed the release of arachidonic acid and its metabolites, NDGA markedly depressed the release of aspartate, glutamate, and GABA. An inhibitor of the 12-lipoxygenase and an inhibitor of nitric oxide synthase did not affect the K+-evoked release of any transmitter amino acid. These results suggest that a 5-lipoxygenase product selectively enhances aspartate release and a cyclooxygenase product selectively depresses glutamate release. They are also consistent with previous evidence that arachidonic acid and/or platelet-activating factor enhances the release and depresses the uptake of glutamate and aspartate. The K+-evoked release of excitatory amino acids is much more sensitive to modulation by lipid mediators than is GABA release. Activation of NMDA receptors may enhance the K+-evoked release of glutamate and aspartate from CA1 slices by stimulating the production and release of lipid modulators.  相似文献   
166.
In a group of captive bonnet macaques (Macaca radiata) housed at the California Primate Research Center, variance in reproductive success among females is primarily due to differences in infant survival. The infants of low-ranking females have a smaller probability of surviving to 6 months of age than do the infants of other females. In addition, the juvenile daughters of low-ranking females are more vulnerable to behaviourally induced mortality than are other immature animals. Observational evidence indicates that this mortality is the direct result of aggression by unrelated, higherranking adult females. Although infants' sex is not consistently related to survival, yearly fluctuations in the survival of male and female infants are reflected in the extent and direction of the skew in the sex ratio of offspring produced the following year. Years in which the highest proportion of male infants survive are followed by years in which the largest proportions of the birth cohorts are composed of males, and years in which the largest proportions of females survive are followed by years in which the largest proportions of birth cohorts are composed of females. For infant females the probability of surviving is reduced when a substantial proportion of the birth cohort is composed of females. The same pattern is evident among the sons of low-ranking females. The adaptive significance of behaviourally induced variation in reproductive success among females is considered in relation to these data.  相似文献   
167.
Purified recombinant human nerve growth factor (rhNGF) and submaxillary gland-derived murine NGF (muNGF) were characterized by amino acid composition, polyacrylamide gel electrophoresis (PAGE), reversed-phase HPLC (RP-HPLC), and high-performance ion-exchange chromatography (HPIEC). Limited tryptic digest of the N and C termini of the 120-residue form of rhNGF produced a species of 109 residues (10-118). The previously observed natural murine analogue of this variant, muNGF lacking the first eight N-terminal amino acids, was also isolated as a homodimer. Both species were purified using HPIEC and characterized by amino acid analysis, N-terminal sequence, PAGE, and RP-HPLC analysis. Each of the four homodimeric species was evaluated in some or all of the following biological assays for NGF: chick dorsal root and sympathetic ganglion assays and rat pheochromocytoma-12 cell line neurite extension assay. The 118-residue homodimeric versions of both rhNGF and muNGF displayed equivalent bioactivity, whereas the N terminal-modified molecules presented activity reduced by 50- to 100-fold. Utilizing HPIEC, we have examined the ability of the monomeric forms of any two of the homogeneous dimeric species of rhNGF to recombine. We have shown that not only can all of the previously described species form dimers by recombination, but an interspecies dimer can be created between muNGF and rhNGF.  相似文献   
168.
Salt marshes may act either as greenhouse gas (GHG) sources or sinks depending on hydrological conditions, vegetation communities, and nutrient availability. In recent decades, eutrophication has emerged as a major driver of change in salt marsh ecosystems. An ongoing fertilization experiment at the Great Sippewissett Marsh (Cape Cod, USA) allows for observation of the results of over four decades of nutrient addition. Here, nutrient enrichment stimulated changes to vegetation communities that, over time, have resulted in increased elevation of the marsh platform. In this study, we measured fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in dominant vegetation zones along elevation gradients of chronically fertilized (1,572 kg N ha?1 year?1) and unfertilized (12 kg N ha?1 year?1) experimental plots at Great Sippewissett Marsh. Flux measurements were performed using darkened chambers to focus on community respiration and excluded photosynthetic CO2 uptake. We hypothesized that N‐replete conditions in fertilized plots would result in larger N2O emissions relative to control plots and that higher elevations caused by nutrient enrichment would support increased CO2 and N2O and decreased CH4 emissions due to the potential for more oxygen diffusion into sediment. Patterns of GHG emission supported our hypotheses. Fertilized plots were substantially larger sources of N2O and had higher community respiration rates relative to control plots, due to large emissions of these GHGs at higher elevations. While CH4 emissions displayed a negative relationship with elevation, they were generally small across elevation gradients and nutrient enrichment treatments. Our results demonstrate that at decadal scales, vegetation community shifts and associated elevation changes driven by chronic eutrophication affect GHG emission from salt marshes. Results demonstrate the necessity of long‐term fertilization experiments to understand impacts of eutrophication on ecosystem function and have implications for how chronic eutrophication may impact the role that salt marshes play in sequestering C and N.  相似文献   
169.
During reproduction, ant colonies produce winged queens. These new queens usually leave the nest to mate and can then establish a new nest. If the new nest is close to an existing colony, it will be in competition with the existing colony. Therefore, workers will kill any mated queens they find outside the colony during the reproductive season. In this study, factors that might determine whether workers eliminate queens were investigated. Mating status (mated or unmated), colony origin (same or different to tested workers) and mating partners (inbred or outbred) of the queens of Japanese harvester ants (Messor aciculatus) were manipulated and the workers’ behavior towards the queens was observed. Mated queens were always attacked by workers, though this was not affected by either colony origin or mating partners. These results suggest that mating status triggers elimination of queens by workers, and that the colony origin and mating partner are unlikely to be important roles in elimination of queens.  相似文献   
170.
Objective: To assess the relationship among recreational physical activity (PA), non‐occupational sedentary behavior, and 7‐year weight gain among postmenopausal U.S. women 40 to 69 years old. Research Methods and Procedures: In 1992 and 1999, 18,583 healthy female participants from the Cancer Prevention Study II Nutrition Cohort completed questionnaires on anthropometric characteristics and lifestyle factors. The associations between recreational PA [in metabolic equivalent (MET) hours per week] and non‐occupational sedentary behavior (in hours per day) at baseline and risk for 7‐year weight gain (5 to 9 or ≥10 vs. ±4 pounds) were assessed using multivariate logistic regression analysis. Results: Neither PA nor sedentary behavior was associated with a 5‐ to 9‐pound weight gain. Among women who were not overweight at baseline (BMI <25.0), the odds of ≥10‐pound weight gain were 12% lower (odds ratio, 0.88; 95% confidence interval, 0.77 to 0.99) for those in the highest category of recreational PA (≥18 MET h/wk) compared with >0 to <4 MET h/wk; odds were 47% higher (odds ratio, 1.47; 95% confidence interval, 1.21 to 1.79) for non‐overweight women who reported ≥6 h/d of non‐occupational sedentary behavior compared with <3 h/d. Neither PA nor sedentary behavior were associated with risk of ≥10‐pound weight gain weight among women who were overweight at baseline (BMI ≥25.0). Discussion: Both recreational PA and non‐occupational sedentary behavior independently predicted risk of ≥10‐pound weight gain among postmenopausal women who were not overweight at baseline. Public health messages to prevent weight gain among normal‐weight postmenopausal women may need to focus on decreasing time spent in sedentary behaviors and increasing the amount of time spent on PA.  相似文献   
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