Local identifiability for two and three-compartment pharmacokinetic models with time-lags

Parkinson's disease (PD), a disorder of unknown etiology, is associated with the degeneration of dopaminergic neurons in nigro-striatal pathways. MPTP, a meperidine analog, causes parkinsonism in human and nonhuman primates. MPP+, the active metabolite of MPTP, inhibits the activity of respiratory chain complex I. In patients with PD, a reduced complex I activity was found in substantia nigra, skeletal muscle, and platelets. Because complex I is partially encoded by the mitochondrial genome, several studies have searched for mitochondrial (mt) DNA abnormalities in patients with PD. Our aim was to answer the following questions: (1) are there some abnormalities of mtDNA in PD? (2) if there are some, what are these abnormalities? and (3) what is the pathogenic role of these abnormalities? METHODS: The literature review was performed using Medline [National Library of Medicine, Washington] and Current Contents [Institute for Scientific Information, Philadelphia] databases. Periods screened were 1966-March, 1998 (Medline) and March 17, 1997-March 9, 1998 (Current Contents). Keywords were: "Parkinson" or "Parkinson's", and "mitochondrial DNA" or "mtDNA". We limited our research to articles in English and French. RESULTS: Medline search provided 59 articles. Current Contents search provided 22 articles. Twelve articles were found in both databases. Thirty-eight of the 69 articles were either reviews about mitochondrial diseases (19 articles) or original articles not related to mtDNA (19 articles). Our final selection included the remaining 31 articles.     

Mammary epithelium disruption and mammary epithelial cell exfoliation during milking in dairy cows

The presence of mammary epithelial cells (MEC) in the milk of ruminants indicates that some MEC are shed from the mammary epithelium; however, the mechanisms that regulate the MEC exfoliation process are not known. Through the release of oxytocin, prolactin, and cortisol and through oxytocin-induced mechanical forces on the mammary epithelium, milking could participate in regulating the MEC exfoliation process. The aims of the present study were to determine the rate of MEC exfoliation throughout milking and to investigate its relationship to mammary epithelium integrity and milking-induced hormone release. Milk samples from 9 Holstein dairy cows producing 40.6 ± 1.36 kg of milk/d were collected at the beginning (after 1 and 2 min), in the middle, and at the end of milking. Milk MEC were purified using an immunomagnetic method. Blood samples were collected before, during, and after milking, and the oxytocin, prolactin, and cortisol concentrations in the samples were measured. Tight junction opening was assessed by plasma lactose concentration and the Na⁺:K⁺ ratio in milk. The somatic cell count in milk varied during the course of milking; it decreased at the beginning of milking and then increased, reaching the highest values at the end of milking. Exfoliated MEC were present in all milk samples collected. The presence of MEC in the milk sample collected during min 1 of milking, likely corresponding to the cisternal milk fraction, suggests that MEC were exfoliated between milkings. The observed increase in the Na⁺:K⁺ ratio in milk and in the plasma concentration of lactose indicated that disruption of mammary epithelium integrity occurred during milking. The MEC exfoliation rate at milking was not correlated with the variables describing milking-induced prolactin release but was negatively correlated with cortisol release, suggesting that cortisol may play a role in limiting exfoliation. In conclusion, milking induced a disruption of the mammary epithelial barrier. Mammary epithelial cells may be continuously exfoliated between milkings or exfoliated during milking as a consequence of the oxytocin-induced mechanical forces and the disruption of mammary epithelium integrity.     

Image overlay guidance for needle insertion in CT scanner

We present an image overlay system to aid needle insertion procedures in computed tomography (CT) scanners. The device consists of a display and a semitransparent mirror that is mounted on the gantry. Looking at the patient through the mirror, the CT image appears to be floating inside the patient with correct size and position, thereby providing the physician with two-dimensional (2-D) "X-ray vision" to guide needle insertions. The physician inserts the needle following the optimal path identified in the CT image rendered on the display and, thus, reflected in the mirror. The system promises to reduce X-ray dose, patient discomfort, and procedure time by significantly reducing faulty insertion attempts. It may also increase needle placement accuracy. We report the design and implementation of the image overlay system followed by the results of phantom and cadaver experiments in several clinical applications.     

Animation of a B-Spline figure

Summary In this paper we describe how the use of B-Spline surfaces allows lissom movements of body and face. Our method is empirical, based on a parametrical animation. It can be combined with a muscles model for facial animation as we illustrated for the speech.     

An Open Two-Compartment Model for a Double Site of Drug Absorption

An open two-compartment model with a double site of drug absorption along the gastrointestinal tract is proposed to describe the pharmacokinetics of a new drug, veralipride. We give the analytical expression of the amount of drug, at any time, in the central compartment after successive oral solution administrations. By computer simulations, plasma level profiles are obtained, which show rebounds and secondary peaks, according to experimental data.     

Correspondenceless stereo and motion: planar surfaces

It is shown that a binocular observer can recover the depth and three-dimensional motion of a rigid planar patch without using any correspondences between the left and right image frames (static) or between the successive dynamic frames (dynamic). Uniqueness and robustness issues are studied with respect to this problem and experimental results are given from the application of the theory to real images     

Uncoupled actuation of pan-tilt wrists

Using algebraic properties of displacement (or rigid-body motion) subsets, the paper introduces new two-degree-of-freedom (2-DOF) nonoverconstrained orientation mechanisms. The angles of pan and tilt are also referred to as the angles of precession /spl psi/ and nutation /spl theta/, respectively, employing the standard terminology of Euler angles. A serial array of two revolute pairs provides the kinematic constraint of an end-effector. For instance, the first axis of rotation is fixed vertically, and the second axis rotates around the first axis, remaining parallel to the horizontal plane. Such a 2-DOF wrist is fit for orienting various devices like telescopes, cameras, antennas, etc. The first axis is fixed, and can be actuated by any powerful heavy servomotor. The paper discloses new mechanisms that allow the actuation of the second movable axis by a fixed servomotor. Moreover, the actuation of the movable axis is not a function of the pan /spl psi/. In other words, the pan and the tilt are controlled independently or in a fully uncoupled manner.     

Oil removal from water by selective sorption on hydrophobic cotton fibers. 1. Study of sorption properties and comparison with other cotton fiber-based sorbents

Hydrophobic cotton fibers, obtained by acylation of cellulose with fatty acid using microwaves radiations, have a high selective affinity for vegetable or mineral oil, fuel, and petroleum, in aqueous medium. Their sorption capacity (SC) (weight of liquid picked up by a given weight of sorbent) is about 20 g/g, after draining. They are reusable after simple squeezing, and their SC reaches a constant value, ca. 12 g/g. Moreover, this product is stable in water, whereas raw cotton can develop molds, after oil sorption. Besides, it is also biodegradable.     

对北京葡萄酒市场和大学生葡萄酒消费群体的调查

通过问卷,对在校大学生进行了葡萄酒市场和营销的调查.结果表明,在购买目的不同时,受访者对葡萄酒的心理期望价格存在明显的差异,自我期望价格在30～80元/瓶,而用于宴请和送礼等活动时,对葡萄酒的期望价格明显提高.产地是影响葡萄酒选购的另一个重要因素,国产酒具有显著的优势,用于自己消费时选购国产酒的占66.4%,对进口酒只有法国葡萄酒具有较高的消费认同度,且集中在以送礼等为目的的高端消费.与价格、产地因素相比,年份对受访群体的葡萄酒选购影响相对较小,同时受访者对葡萄酒的星级与获奖的信任程度也很低.