65 research outputs found
Grading systems in head and neck dysplasia: their prognostic value, weaknesses and utility
Contains fulltext :
80594.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Grading of dysplasia, including head and neck lesions, continues to be a hotly debated subject. It is subjective and lacks intra- and inter-observer reproducibility due to the insufficiency of validated morphological criteria and the biological nature of dysplasia. Moreover, due to the absence of a consensus, several systems are currently employed. OBJECTIVES: The aims of this review are to:1) Highlight the significance of dysplasia and the importance of a valid method for assessing precursor lesions of the head and neck.2) Review the different histopathological classification systems for grading intraepithelial lesions of the head and neck.3) Discuss and review quality requirements for these grading systems. CONCLUSION: Regarding the different classification systems, data concerning the WHO classification system are the most available in current literature. There is no simple relationship or overlapping between the classification systems. Further studies should be done to see whether other systems have advantages above the current WHO system and to discover indications that could lead to an universal classification system for intraepithelial lesions of the head and neck
A Prospective Study of Adverse Pregnancy Outcomes Among Planned and Unplanned Pregnancies in Natural Family Planning Users
Objectives. To prospectively determine whether unplanned
pregnancies are associated with adverse pregnancy outcomes among
users of natural family planning (NFP).
Methods. Women who became pregnant while using NFP were
identified in five centers worldwide: there were 373 unplanned
and 367 planned pregnancies. Subjects were followed up at 16 and
32 weeks gestation and after delivery. The risks of spontaneous
abortion, low birth weight and preterm birth were estimated after
adjustment by logistic regression.
Results. The women with unplanned pregnancies were more likely to
be at the extremes of age, to report more medical problems before
and during the index pregnancy, and to seek antenatal care later
in gestation than the women with planned pregnancies. However,
women with planned pregnancies reported a higher rate of
spontaneous abortion in prior pregnancies (28.8%) than did women
with unplanned pregnancies (12.9%, p<0.001). There were no significant differences in the rates of spontaneous abortion, low
birth weight or preterm birth in the two groups.
Conclusions. No increased risk of adverse pregnancy outcomes was
observed among women who experienced an unplanned pregnancy
during NFP use. (Am J Public Health. 1996:00:0000-0000).Supported by grant BR-US-004 from the U.S. Agency for International Development and the Institute for International Studies in Natural Family
Planning, Georgetown University, and The Johns
Hopkins University, Population Center grant #5
P30-HD06268 from the National Institute of Child
Health and Development
The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds
Most non-avian theropod dinosaurs are characterized by fearsome serrated teeth and sharp recurved claws. Interpretation of theropod predatory ecology is typically based on functional morphological analysis of these and other physical features. The notorious hypertrophied ‘killing claw’ on pedal digit (D) II of the maniraptoran theropod Deinonychus (Paraves: Dromaeosauridae) is hypothesized to have been a predatory adaptation for slashing or climbing, leading to the suggestion that Deinonychus and other dromaeosaurids were cursorial predators specialized for actively attacking and killing prey several times larger than themselves. However, this hypothesis is problematic as extant animals that possess similarly hypertrophied claws do not use them to slash or climb up prey. Here we offer an alternative interpretation: that the hypertrophied D-II claw of dromaeosaurids was functionally analogous to the enlarged talon also found on D-II of extant Accipitridae (hawks and eagles; one family of the birds commonly known as “raptors”). Here, the talon is used to maintain grip on prey of subequal body size to the predator, while the victim is pinned down by the body weight of the raptor and dismembered by the beak. The foot of Deinonychus exhibits morphology consistent with a grasping function, supportive of the prey immobilisation behavior model. Opposite morphological trends within Deinonychosauria (Dromaeosauridae + Troodontidae) are indicative of ecological separation. Placed in context of avian evolution, the grasping foot of Deinonychus and other terrestrial predatory paravians is hypothesized to have been an exaptation for the grasping foot of arboreal perching birds. Here we also describe “stability flapping”, a novel behaviour executed for positioning and stability during the initial stages of prey immobilisation, which may have been pivotal to the evolution of the flapping stroke. These findings overhaul our perception of predatory dinosaurs and highlight the role of exaptation in the evolution of novel structures and behaviours
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