SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A three dimensional reconstruction of the epithelial tissue at the apical end of the lower rat incisor was made from serial 1 mum thick cross sections. This tissue formed an elongated structure, called the odontogenic organ, which was composed of a bulbous and a "U"-shaped part. Both parts were joined to one another at the posterior aspect of the apical foramen. The bulbous part of the odontogenic organ was situated at the lingual side of the "U"-shaped part and protruded anteriorly over the pulp. It was formed by cells of the outer dental epithelium and stellate reticulum whose organization suggested that the bulbous part was important in the production of cells for renewal of all the epithelia of the incisor. The "U"-shaped part of the odontogenic organ was apparently derived from the bulbous part and delineated the pulp by forming the lateral, mesial and labial sidewalls around the apical foramen. It was composed of all the epithelial cell types recognizable as precursors to (a) cells of the enamel organ which form the enamel, and (b) Hertwig's epithelial root sheath, a part of the odontogenic organ which induces the formation of dentin on the lingual aspect of the incisor.
The ontogenetic developments of the pineal organ, parapineal organ, and retina were studied by the use of light and electron microscopy in embryos and fry of the teleost, Gasterosteus aculeatus, from 60 to 168 h after fertilization. Sixty to 66 h after fertilization, the primordium of the pineal complex is discernible in the diencephalic roofplate; the parapineal anlage is located rostral to the pineal anlage. Photoreceptor cells endowed with outer segments are present in the embryonic pineal organ already after 72 h, whereas outer segments of retinal photoreceptors could not be demonstrated before 144 h (hatching occurs between 120-144 h). Furthermore, neuropil formations with synaptic specializations are present in the rostral part of the pineal organ 108 h after fertilization. At 72 h, the embryonic parapineal parenchyma is already differentiated into parapinealocytes, which give rise to the parapineal tract, and glia-resembling elements. Although parapinealocytes carry cilia (9 X 2 + 0), only a single outer segment of the photoreceptor type could be demonstrated in the parapineal organ of one adult stickleback. Photoreceptors present in the pineal organ of unhatched embryos are hardly involved in visual functions, but may already at this early developmental stage serve as photoneuroendocrine transducers.
We undertook a study in Albany, New York, to investigate whether volatile organic compounds (VOCs) were measurable in the blood and in the breathing-zone air of people exposed to gasoline fumes and automotive exhaust. We sampled blood of 40 subjects, placed organic vapor badges on 40 subjects, and obtained personal breathing-zone samples from 24 subjects. We limited this analysis to 19 subjects who wore the organic vapor badges for at least 5 h. VOC levels, as determined by the organic vapor badges, were highly correlated with blood levels of these same compounds. Using detection in blood as the gold standard, we found the badges to be more sensitive than conventional charcoal tube samples in detecting low levels of methyl tert-butyl ether (0.60 vs 0.08), toluene (0.95 vs 0.64), and o-xylene (0.85 vs 0.64). In this study, organic vapor badges provided data on VOC exposure that correlated with blood assay results. These organic vapor badges might provide a convenient means of determining human exposure to VOCs in epidemiologic studies.
Three-dimensional organoids of the gut, liver, and lung have become mainstream models of human development, disease, and therapy. These organs share an embryonic endodermal origin, yet the field measures their progress inconsistently because the word "maturity" carries two unrelated meanings. Herein, we review the organoid work across all three organs and propose that the two orthogonal axes of advancement be analyzed separately. The first axis is single-organ fidelity. Adult stem cell organoids are faithful but partial, reproducing the adult epithelium of their source tissue with genomic stability yet lacking stromal, vascular, immune, and neural compartments. Human pluripotent stem cell organoids are complete but immature, co-emerging with multiple lineages yet arrested in a fetal-like state. The cost of each limitation is organ-dependent, smallest in the intestine, largest for hepatic drug metabolism, and most spatially defined across the proximal and distal lungs. The second axis is inter-organ reconstruction, where progress is strongly asymmetric. The gut-liver axis is comparatively advanced and sustained by linked organoid and microphysiological systems. The gut-lung axis, by contrast, remains the least-developed frontier, and no such linked organoid has yet been built. We therefore frame it as a proposal, using in vivo and correlative evidence to outline the design principles for such a model. Four bottlenecks recur across both axes: limited vascularization; batch-to-batch variability; organ-skewed immune, microbial, and stromal microenvironments; and unidirectional signaling. We argue that benchmarking models against single-cell developmental atlases and prioritizing construction of the gut-lung frontier should guide the field over the next decade.
Analysis of the organization of a specific chromosomal gene, the gene for rRNA in Xenopus laevis, has evidenced a close relationship between loop organization, replication organization, and expression units. The nontranscribed spacer appears to be involved in all three levels of organization. Furthermore the replication origin region appears to be involved in nuclear matrix anchorage and is closely related to the 40 S transcription promoter. This organization suggests how expression domains may be regulated and how this functional organization may be transmitted to daughter cells after DNA replication, thus allowing selected expression patterns not to be lost during development.
Roller tube cultures of parasagittal cerebellar slices were taken from young rats aged 9-11 days, and maintained in vitro for 1-2 weeks. Morphological aspects of cell types and synaptic relationships in such organ cultures were examined at light and electron microscopic levels. Some neurons were marked by intracellular injections of horseradish peroxidase for subsequent identification of their connection patterns. Cytoarchitecture of the cerebellar cortex was largely preserved in the organ cultures. Dendritic trees of Purkinje cells exhibited isoplanar organizations that often resembled their orientation at the time of explanation. Other cerebellar neurons, namely granule cells, Golgi cells, basket cells, stellate cells, all differentiated within the organ cultures. In addition, some neurons of the deep cerebellar nuclei remained viable during the period of culture. Mossy fibers most probably of cerebellar nuclear origin were found terminating on the dendrites of granule cells and Golgi cells. Quite unexpected were certain types of direct synapses of afferent fibers on short necked spines arising from Purkinje cell smooth dendrites and somata. Such terminals resembled climbing fibers. They were most likely modified mossy fiber afferents, since the organ cultures did not include neurons of the inferior olive which are well spearated from the cerebellar mass at postnatal stages. These "ascending" mossy fibers presumably occupied postsynaptic surfaces that were either vacated by deafferentation or induced by the afferent fibers themselves. Intracellularly labeled Purkinje cells had widely distributed axonal collateral branches. Labeled axons were distributed within the Purkinje cell layer. Several recurrent Purkinje cell axon collaterals stained with reaction products of horseradish peroxidase tracer were followed at the ultrastructural level. In one case, labeled terminals were examined in an area of approximately 2 mm2. Terminals of Purkinje cell collaterals formed symmetric synapses with somata of basket cells and dendrites of Golgi cells, but not Purkinje cell somata. Some large boutons of serially traced Purkinje cell axon collaterals formed asymmetric contacts with profiles interpreted as Golgi cell dendrites. In contrast to the apparent axonal sprouting in cerebellar organ cultures, maturation of dendritic processes remained static. Astroglia cells of diverse shapes were observed following immunocytochemical staining with antisera to glia filament proteins. The distribution patterns of immunoreactive astrocytes changed dramatically in cerebellar slice cultures maintained for 3-6 weeks in vitro.
BACKGROUND: A multi-organ donor seronegative for hepatitis C virus (HCV) by 1st generation enzyme immunoassay (EIA) supplied 5 solid organs and 2 corneas to 7 recipients. This donor was retrospectively shown to be 2nd generation HCV EIA-positive and polymerase chain reaction (PCR)-positive. All 5 solid organ recipients but none of the corneal recipients developed HCV infection. OBJECTIVES: To demonstrate the discordance between serological and PCR-based HCV detection in solid organ transplant recipients and the lack of transmission of HCV to the two corneal transplant recipients. STUDY DESIGN: All 5 solid organ recipients were retrospectively shown to be HCV PCR-negative and -seronegative pre-transplant and HCV PCR-positive post-transplant. Serial serum samples on 3 recipients were evaluated by 2nd generation EIA, a prototypic structural and non-structural dual bead assay (EIA-SA, Abbott), the Chiron Recombinant Immunoblot Assay, 2nd generation (RIBA-2), and the Chiron RIBA HCV Test System Strip Immunoblot Assay 3.0 (RIBA-3, Chiron). RESULTS: The dual bead EIA-SA and RIBA-3 were able to detect HCV seroconversion approximately 6 months earlier than the 2nd generation EIA in 2 recipients, and in 1 recipient only PCR detected infection within the first 10 months. There was no evidence of HCV transmission to the corneal recipients. CONCLUSIONS: Although third generation assays such as the RIBA-3 and EIA-SA narrowed the window of HCV seronegativity in transplant recipients compared with the 2nd generation EIA, PCR was the most sensitive method of detecting acute HCV infection. Despite transmission of HCV to all of the solid organ recipients HCV was not transmitted to the corneal transplant recipients.
Stable isotope ratios were used to determine the impact of anthropogenically derived organic matter from onshore and offshore fish farming and a sewage outfall on organisms at different trophic levels (primary producers and consumers) on the south-east coast of Sicily (Italy, Mediterranean). Representative macroalgae and consumers were collected in three sampling locations: "Impact" and two putative "Controls" sited to the north of the impacted location. While delta(13)C values of both organic matter sources and consumers varied little between locations, delta(15)N spatial variability was higher and delta(15)N was shown to be a good descriptor of organic enrichment and uptake of anthropogenically derived material within coastal food webs. Isotopic data were analysed using a multivariate approach. Organic matter sources and benthic components were more sensitive to pollution than nektobenthic species and revealed that the effects of anthropogenic activities seem to be detectable over a wide area. The study site is characterised by wide waste dispersal, which brings a reduction in impact in the area directly affected by organic matter inputs and enlarges the area of moderate impact.
Within administrative surveying work in Sweden, a transition to a client-centered team-based organization was made during 1998. The aim of this study was to describe the employees' perceptions and expectations of job and organizational practices when working as a generalist in a client-centered team-based organization; job and organizational practices and well-being and effectiveness measures were examined when introducing a team-based organization. Interventions such as courses in how to cope with the role of a generalist, how to increase service to clients, education in technology, law and economics, as well as computer information support, were ongoing at the time of the study. The Team Work Profile and QPS Nordic questionnaires were used. All the surveyors in five regions in Sweden participated, in total 640 surveyors. The transition to a client-centered team-based organization was expected to improve job control and job content but at the same time lead to impairments in job climate and group cohesion. Distress was associated with negative future expectations of the organization. High job control and group cohesion were the central contributors towards growth in personal competence and social effectiveness of teamwork. Both internal and external client-related activities of team and organization were in focus during the transition.
Dissolved natural organic matter (NOM) plays an essential role in freshwater geochemical and biochemical processes. A major property, its redox behavior, can be attributed to the chinone building blocks, which can form stable radicals. However, electron paramagnetic resonance (EPR) data indicating free radicals on solid NOM are sparse. Here we present EPR spectra of 23 NOM from European surface waters isolated by reverse osmosis. The organic radical concentrations of NOM ranged from 5 x 10(15) to 1.84 x 10(17) spins g(-1), and g values ranged from 2.0031 to 2.0045. Number and type of organic radicals in solid NOM are significantly influenced by the pH of raw water. EPR experiments indicate the presence of semiquinone-type radicals in coexistence with carbon-centered "aromatic" radicals, with the semiquinone-type radicals dominating at alkaline pH. Basically these processes are reversible. Organic radical concentrations in NOM adjusted to pH 6.5 before freeze-drying correlate with iron and aluminum contents. UV- and VIS-irradiation of solid NOM can lead to more than a 10-fold increase of the concentration of organic radicals. These radicals were long-lived and had the same g value as the original radical. Similar effects were not observed with isolated humic and fulvic acids, demonstrating the limited reflection of environmental properties of organic carbon by the classical isolation procedure.
Many types of organic aerosol material have been found to behave as viscous liquids. In the current work, photodegradation of selected nitrated polycyclic aromatic compounds, 1-nitropyrene and 3-nitrofluoranthene, in viscous organic phases used as model systems for organic aerosols has been investigated. Experiments have been conducted in the presence and absence of anthraquinone, an atmospherically relevant photochemical radical sensitizer. The photodegradation of nitro-PAH is strongly accelerated by the presence of anthraquinone, and a viscous medium does not inhibit the photoinduced decay of nitro-PAH. In fact, the effect of anthraquinone is more pronounced in a viscous solvent containing tertiary hydrogen, DOP, compared to cyclohexane, a nonviscous solvent. This is related to a faster decay of anthraquinone in DOP and hence, presumably, a higher radical yield in DOP. The nitro-PAH degradation in DOP is faster at higher temperature; an observation primarily ascribed to faster diffusion at higher temperature giving rise to more efficient radical formation. In glycerine, a polar viscous solvent, significant formation of amino-PAH occurs due to photoreduction of the nitro-PAH. This is also the case in N2-purged guaiacol, a model substance for wood smoke organic material. Nitro-PAH photoreduction is enabled by the presence of hydrogen-atom donors and low levels of dissolved O2. A simple approach to estimate the O2 concentration in atmospheric organic aerosol material is presented. Low levels of O2 are predicted for wood smoke and secondary organic aerosol making amino-PAH formation in this aerosol material an interesting possibility.