Comparative embryology of basal angiosperms.

Recent phylogenetic analyses of basal angiosperms have identified those lineages central to the study of the origin and early diversification of flowering plants. As we begin to understand the early evolution of endosperm developmental patterns in flowering plants, it is apparent that we know little about the other basic embryological features of basal angiosperms, such as the nature of the female gametophyte and even whether a process of double fertilization occurs.

Emotional conversations in Parkinson's disease.

Objective: To learn how PD influences verbal description of emotional events.

Background: Individuals with PD exhibit emotional processing deficits. Emotional experience likely involves several dimensions (e.

Changes in vocal intensity in Parkinson's disease following pallidotomy surgery.

The present study was designed to examine changes in vocal intensity following unilateral posteroventral pallidotomy (PVP) in a large sample of speakers with Parkinson's disease (PD) that exhibited a range of hypokinetic dysarthria. Twenty-five persons with PD were recorded using a variety of speech tasks, once prior to and once following PVP. The pre-PVP vocal SPL was subtracted from the post-PVP vocal SPL to derive a relative change in vocal SPL.

A geometrically based method for automated radiosurgery planning.

Purpose: A geometrically based method of multiple isocenter linear accelerator radiosurgery treatment planning optimization was developed, based on a target's solid shape.

Methods And Materials: Our method uses an edge detection process to determine the optimal sphere packing arrangement with which to cover the planning target. The sphere packing arrangement is converted into a radiosurgery treatment plan by substituting the isocenter locations and collimator sizes for the spheres.

Release of lead-containing particles from a wall enclosure.

The 1995 Department of Housing and Urban Development (HUD) Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing discusses using interior and exterior wall enclosures for lead hazard control. Leaded dust may be aerosolized inside enclosures and released through gaps and cracks into a room. The effects of airflow and mechanical disturbances on dust release were studied using a laboratory wall enclosure model with dust collected from homes with lead-based paint hazards.

The development of children's knowledge of the times of future events.

Four studies with 261 children were conducted to describe 4- through 10-year-olds' ability to differentiate the future distances of events. Distances ranged from later the same day through nearly a year in the future. Judgment methods included pointing to parts of a spatial scale representing future distances and answering open-ended questions.

Neurotrophins induce death of hippocampal neurons via the p75 receptor.

Nerve growth factor (NGF) and related neurotrophins influence neuronal survival and differentiation via interactions with the trk family of receptors. Recent studies have demonstrated that neurotrophins may also induce cell death via the p75 receptor. The importance and generality of neurotrophin-induced death in the brain have not been defined but may play a critical role during development and in disease-associated neuronal death.

The origin and early evolution of tracheids in vascular plants: integration of palaeobotanical and neobotanical data.

Although there is clear evidence for the establishment of terrestrial plant life by the end of the Ordovician, the fossil record indicates that land plants remained extremely small and structurally simple until the Late Silurian. Among the events associated with this first major radiation of land plants is the evolution of tracheids, complex water-conducting cells defined by the presence of lignified secondary cell wall thickenings. Recent palaeobotanical analyses indicate that Early Devonian tracheids appear to possess secondary cell wall thickenings composed of two distinct layers: a degradation-prone layer adjacent to the primary cell wall and a degradation-resistant (possibly lignified) layer next to the cell lumen.

A high-precision system for conformal intracranial radiotherapy.

Purpose: Currently, optimally precise delivery of intracranial radiotherapy is possible with stereotactic radiosurgery and fractionated stereotactic radiotherapy. We report on an optimally precise optically guided system for three-dimensional (3D) conformal radiotherapy using multiple noncoplanar fixed fields.

Methods And Materials: The optically guided system detects infrared light emitting diodes (IRLEDs) attached to a custom bite plate linked to the patient's maxillary dentition.

Stereotactic radiosurgery: techniques and clinical applications.

Radiation is a common treatment modality for cancer. Although commonly used, the treatment techniques of radiation delivery have changed substantially. One of the most important changes in implementation is the widespread application of stereotactic techniques and their acceptance into the mainstream of radiotherapeutic delivery.

Calculation of cranial nerve complication probability for acoustic neuroma radiosurgery.

Purpose: Estimations of complications from stereotactic radiosurgery usually rely simply on dose-volume or dose-diameter isoeffect curves. Due to the sparse clinical data available, these curves have typically not considered the target location in the brain, target histology, or treatment plan conformality as parameters in the calculation. In this study, a predictive model was generated to estimate the probability of cranial neuropathies as a result of acoustic schwannoma radiosurgery.

Image localization for frameless stereotactic radiotherapy.

Purpose: Infrared light-emitting diodes (IRLEDs) have been used for optic-guided stereotactic radiotherapy localization at the University of Florida since 1995. The current paradigm requires stereotactic head ring placement for the patient's first fraction. The stereotactic coordinates and treatment plan are determined relative to this head ring.

Linear accelerator radiosurgery in the management of brain tumours.

Radiosurgery is an increasingly popular method for treating a variety of intracranial tumours. A great deal of treatment data has been accumulated suggesting that radiosurgery may be the treatment of choice for small acoustic schwannomas. Moreover, radiosurgery promises excellent tumour control and minimal risk in the treatment of small meningiomas in risky surgical locations such as the cavernous sinus.

Autocrine expression and ontogenetic functions of the PACAP ligand/receptor system during sympathetic development.

The superior cervical ganglion (SCG) is a well-characterized model of neural development, in which several regulatory signals have been identified. Vasoactive intestinal peptide (VIP) has been found to regulate diverse ontogenetic processes in sympathetics, though functional requirements for high peptide concentrations suggest that other ligands are involved. We now describe expression and functions of pituitary adenylate cyclase-activating polypeptide (PACAP) during SCG ontogeny, suggesting that the peptide plays critical roles in neurogenesis.

Cognitive and vestibulo-proprioceptive components of spatial ability in Parkinson's disease.

Visual-spatial deficits are often associated with Parkinson's Disease (PD). Recent theories suggest that frontal-basal ganglionic dysfunction affects cognition in PD. Although this hypothesis does not entirely explain spatial deficits in PD, the inappropriate utilization of cues associated with executive dysfunction may induce spatial deficits.

Age-Dependent Changes in the Effects of Amiodarone on Rabbit Cardiac Myocyte Contractions.

BACKGROUND: Intravenous amiodarone has increasingly been used to control life-threatening atrial and ventricular arrhythmias. In addition to its four antiarrhythmic properties, amiodarone may have complex effects on intracellular Ca(2+) stores and myocyte contractility. METHODS AND RESULTS: Contraction amplitude was recorded for cardiac ventricular myocytes isolated from neonatal and adult rabbits.

Caspase-2 mediates neuronal cell death induced by beta-amyloid.

beta-amyloid (Abeta) has been proposed to play a role in the pathogenesis of Alzheimer's disease (AD). Deposits of insoluble Abeta are found in the brains of patients with AD and are one of the pathological hallmarks of the disease. It has been proposed that Abeta induces death by oxidative stress, possibly through the generation of peroxynitrite from superoxide and nitric oxide.

Analytic characterization of linear accelerator radiosurgery dose distributions for fast optimization.

Linear accelerator (linac) radiosurgery utilizes non-coplanar arc therapy delivered through circular collimators. Generally, spherically symmetric arc sets are used, resulting in nominally spherical dose distributions. Various treatment planning parameters may be manipulated to provide dose conformation to irregular lesions.

Neurotrophin signaling via Trks and p75.

This review focuses on recent advances in our understanding of receptor-mediated signaling by the neurotrophins NGF, BDNF, NT3, and NT4/5. Two distinct receptor types have been distinguished, Trks and p75. The Trks are receptor tyrosine kinases that utilize a complex set of substrates and adapter proteins to activate defined secondary signaling cascades required for neurotrophin-promoted neuronal differentiation, plasticity, and survival.

A developmental and evolutionary analysis of embryology in Platanus (platanaceae), abasal eudicot.

The Platanaceae are an early derived eudicot lineage and therefore occupy a key position for understanding reproductive character diversification associated with the early evolutionary radiation of flowering plants. We conducted an embryological study of Platanus racemosa in order to provide critical data on defining angiosperm reproductive characters for this important group. Female gametophyte development is monosporic.

Voice and speech characteristics of persons with Parkinson's disease pre- and post-pallidotomy surgery: preliminary findings.

Pallidotomy surgery, lesioning the globus pallidus internal, has been performed to alleviate Parkinsonian symptoms and drug-induced dyskinesias. Improvements in limb motor function have been reported in recent years following pallidotomy surgery. The purpose of this preliminary study was to determine the effect of pallidotomy surgery on select voice and speech characteristics of 6 patients with Parkinson's disease.