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At least 397 records · Page 22Linked to original sources
PubMed2006

Recursive partitioning for the prediction of cytochromes P450 2D6 and 1A2 inhibition: importance of the quality of the dataset.

The purpose of this study was to explore the use of detailed biological data in combination with a statistical learning method for predicting the CYP1A2 and CYP2D6 inhibition. Data were extracted from the Aureus-Pharma highly structured databases which contain precise measures and detailed experimental protocol concerning the inhibition of the two cytochromes. The methodology used was Recursive Partitioning, an easy and quick method to implement. The building of models was preceded by the evaluation of the chemical space covered by the datasets. The descriptors used are available in the MOE software suite. The models reached at least 80% of Accuracy and often exceeded this percentage for the Sensitivity (Recall), Specificity, and Precision parameters. CYP2D6 datasets provided 11 models with Accuracy over 80%, while CYP1A2 datasets counted 5 high-accuracy models. Our models can be useful to predict the ADME properties during the drug discovery process and are indicated for high-throughput screening.

Artificial Intelligence↗
PubMed2006

Cell surface glycans: the why and how of their functionality as biochemical signals in lectin-mediated information transfer.

Calculations of the coding capacity of biomolecules come up with the striking result that carbohydrates excel nucleotides and amino acids by far in this respect. Consequently, glycans are ideally suited to equip cell surfaces with a maximum of signals in a minimum of space and form the cellular glycome. The ensuing concept of the sugar code interprets glycans as a platform for encoding messages and shifts in the glycome as a means to swiftly add/remove signals. Next, it implies the presence of effectors that read the signals in situ. Fittingly, recent work on natural decoding devices in mammals (endogenous lectins) has revealed not only their presence but a level of complexity that matches the structural diversity of glycans. The emerging importance of lectin-ligand interaction in immune regulation calls for an introduction to this concept for nonspecialists. This primer to the fundamentals of the sugar code, with telling examples from the realm of immunology, also illustrates the strategic and hitherto unsuspected fine-tuning between glycan structure and lectin design/expression.

Animals↗
PubMed2003

Revolutionary advances in adaptive seating systems for the elderly and persons with disabilities that assist sit-to-stand transfers.

The independence of elderly and arthritic patients as well as persons with disabilities is influenced considerably by their ability to stand from a chair. The presence of pain, reduced joint range of motion, stiffness, and muscle weakness often limit the ability to achieve a sit-to-stand position (STS). Realizing the enormous implications of STS performance, physicians, scientists, and industry have joined together to design and manufacture a wide variety of adaptive seating systems that facilitate therising process. These systems can be divided into three groups: those without mechanical devices, those with mechanical lifts, and those that can lift, tilt in space, recline, or rock. The design of mechanical seating systems without mechanical assists have been influenced by several factors, including chair height, armrest height, and foot position of the occupant. The evaluation of STS performance involves a variety of measurements to include joint angles and moments, speed of time to rise, functional reach and sway, and perception of patient stability (or perceived safety) in rising from a chair. These studies reported that chair seat height, use of armrest, and foot position had a major influence on the ability to do a STS movement. The use of higher chair seats resulted in lower moments at the knee and hip level. Investigators reported that lowering the chair height increased the need for momentum generation or repositioning of the feet to lower the needed moments. They found that the use of an armrest reduced the moments needed at the hip without altering the range of motion of the joints. These investigators found that repositioning of the feet influenced the strategy of STS movement, allowing lower mean extension moments at the hipwhen the foot position changed from anterior to posterior. Adaptive seating systems with lifts include the spring-booster chair spring-loaded flap seat, and ejector chair. Innovative investigators reported that increased seat height complemented by the mechanical lift enhanced STS transfers by persons with disabilities. The investigators noted that it was easier to perform STS transfer when using a mechanical lift than when rising unassisted or from a raised seat height. The latest adaptive seating system, the elevator chair, has the unique ability to assist the occupant to the STS position. The rear section of this chair remains in a fixed position to support the buttocks of the user during the mechanical lift. The front portion of the seat folds down incrementally as the chair rises to allow the feet of the user to be positioned firmly on the floor. Using an elevator chair, the height that the chair rises will vary with the length of the occupant's legs. When the user reaches a point when his/her legs are comfortably straight and the body is in an erect position, the occupant will walk unassisted from the chair. This elevator chair will soon be available with a tilt-in-space capability as well as a gently rocking motion. The elevator chairs are ideally suited for offices, waiting rooms, hospitals, long-term care facilities, and homes. While persons with disabilities appreciate the benefits of these adaptive seating systems, which allow them to achieve a STS position without assistance, healthcare personnel also value the benefits of these adaptive seating systems because they eliminate their need to lift the occupant to a standing position--an invitation for a potentially serious back injury.

Activities of Daily Living↗
PubMedDate not supplied

[Sliding mechanics in orthodontic treatment with the straight wire].

The principles of straight arch technique are described and the mechanical characteristics of contemporary pretorqued, preangulated "straight arch" appliances are summarized. A step wise approach is presented for efficient orthodontic tooth movement using sliding mechanics with .022" straight arch appliances. The steps are: 1) alignment and leveling; 2) molar correction and space closure; 3) finishing. Specific suggestions are made for wires and force elements best suited to sliding mechanics.

Adolescent↗
PubMedDate not supplied

[Air quality monitoring on the International Space Station].

Chemical contamination of air in space cabins occurs mainly due to permanent offgassing of equipment and materials, and leaks. Methods and means of qualitative and quantitative air monitoring on the ISS are powerful enough as for routine so emergency (e.g. local fire, toxic leak) air control. The ISS air quality has suited to the adopted standards and crew safety requirements. Yet, there is a broad field of action toward improvement of the space cabin air monitoring.

Air Pollution, Indoor↗
PubMedDate not supplied

Epidural anesthesia for postpartum tubal ligation using epidural catheters placed during labor.

STUDY OBJECTIVES: To evaluate the success of epidural anesthesia for postpartum tubal ligation using epidural catheters placed during labor and to determine whether patient characteristics, timing of surgery, or technical factors (e.g., length of epidural catheter inserted into the epidural space) influenced the success of subsequent epidural anesthesia. DESIGN: Retrospective study. SETTING: University hospital labor and delivery suite. PATIENTS: 90 consecutive women scheduled for postpartum tubal ligation using epidural catheters placed during labor. INTERVENTIONS: Epidural catheters were reinjected with 1.5% to 2% lidocaine with epinephrine 5 micrograms/ml or 2% to 3% 2-chloroprocaine immediately before surgery. MEASUREMENTS AND MAIN RESULTS: 74% of the women received satisfactory intraoperative anesthesia using in situ epidural catheters. Reinjecting the catheter within 4 hours of delivery was associated with a greater frequency of successful epidural anesthesia for tubal ligation (95% vs. 67%; p = 0.029). There was no significant difference between the two groups in the length of catheter inserted into the epidural space. CONCLUSIONS: Although other factors may influence the timing of postpartum tubal ligation after delivery, the success of epidural anesthesia for tubal ligation using in situ epidural catheters is greater if surgery is performed shortly after delivery.

Adult↗
PubMed1995

Effective water model for Monte Carlo simulations of proteins.

We present an effective theory for water. Our goal is to formulate an accurate model for the effects of solvation on protein dynamics, without incurring the huge computational cost and the slow temporal evolution typical of molecular dynamics simulations of liquids. We replace the individual water molecules in an all-atom potential with a local dielectric density field, with self-interactions given by the Landau-Ginzburg free energy and external interactions by Lennard-Jones forces at the surface of the protein atoms. We explore conformational space with finite temperature Monte Carlo dynamics, using parallel Langevin and Fourier acceleration algorithms well suited to data-parallel computer architectures such as the Connection Machine. To establish the validity of our approximations, we compare our electrostatic contribution to the solvation energy with the results of Lim, Bashford, and Karplus using a conventional static continuum dielectric cavity model, and the nonelectrostatic contributions with estimates of hydrophobic surface free energy. Our model can also accommodate ionic charges and temperature fluctuations. We propose future investigations extending our effective theory of solvation to include explicit orientational entropy and hydrogen-bonding terms.

Models, Molecular↗
PubMed2004

Quantum dynamics calculations using symmetrized, orthogonal Weyl-Heisenberg wavelets with a phase space truncation scheme. II. Construction and optimization.

In this paper, we extend and elaborate upon a wavelet method first presented in a previous publication [B. Poirier, J. Theo. Comput. Chem. 2, 65 (2003)]. In particular, we focus on construction and optimization of the wavelet functions, from theoretical and numerical viewpoints, and also examine their localization properties. The wavelets used are modified Wilson-Daubechies wavelets, which in conjunction with a simple phase space truncation scheme, enable one to solve the multidimensional Schrodinger equation. This approach is ideally suited to rovibrational spectroscopy applications, but can be used in any context where differential equations are involved.

Journal Article↗
PubMed1984

Safe decontamination of hospital autopsy rooms and ventilation system by formaldehyde generation.

Space decontamination was required prior to the onset of a remodeling project in the autopsy suite of a large university-hospital complex. The National Institutes of Health procedure using formaldehyde gas as a disinfectant was modified to decontaminate not only the three autopsy rooms but also the exhaust ductwork and the three associated air incinerators. Modifications included an automated formaldehyde gas generator, a smoke test procedure for leaks, and an exhausting technique. This procedure proved to be successful and has the advantage of including the safety features necessary to conduct such a potentially hazardous decontamination in an occupied hospital.

Autopsy↗
PubMed1998

Molecular shape comparisons in searches for active sites and functional similarity.

Here we examine the reliability of surface comparisons in searches for active sites in proteins. Detection of a patch of surface on one protein which is similar to an active site in another, may suggest similarities in enzymatic mechanisms, in enzyme functions and implicate a potential target for ligand/inhibitor design. Specifically, we compare the efficacy of molecular surface comparisons with comparisons of surface atoms and of C(alpha) backbone atoms. We further investigate comparisons of specific atoms, belonging to a predefined pattern of catalytic residues versus comparisons of molecular surfaces and, separately, of surface atoms. This aspect is particularly relevant, as catalytic residues may be (partially) buried. We also explore active site comparisons versus comparisons in which the entire molecular surfaces are scanned. While here we focus on the geometrical aspect of the problem, we also investigate the effect of adding residue labels in these comparisons. Our extensive studies cover the serine proteases, containing the highly conserved triad motif, and the chorismate mutases. Since such active site comparisons entail comparisons between unconnected points in 3D space, an order-independent comparison technique is necessary. The geometric hashing algorithm is ideally suited to handling such a task. It can perform both global shape matching for the whole surfaces of large protein molecules and searching for local shape similarities for small surface motifs. Our results show that molecular surface comparisons work best when the similarity is high. As the similarity deteriorates, the number of potential solutions increases rapidly, making their ranking difficult, particularly when scanning entire molecular surfaces. Utilizing atomic coordinates directly appears more adequate under such circumstances.

Binding Sites↗
PubMed2005

Confidentiality with respect to third parties: a psychoanalytic view.

It is assumed that confidentiality is not one singular ethical entity but a conglomerate of quite different issues depending upon clinical context and the sector of information sharing at stake. The focus here is on how to think psychoanalytically about requests for information from third parties (payers, courts, public security). Defining confidentiality as a promise to 'never tell anything' outside of the relationship omits evaluation of the impact of the third's listening on the combined freedom of thought and freedom of speech in analyst and analysand. Circulation of information outside the dyad need not be toxic, need not disrupt the analytic couple's openness to new meaning. Key to contamination and inhibition of analytic work is whether or not disclosure serves an analytic end. Current defense of confidentiality relies heavily on the models of protection of privacy and professional secrecy, which, though useful and relevant, fail to encompass the transitional, intersubjective space engendered by the analytic process. Suggestions are made for alternate sources of paradigms better suited to represent the latter. Offered for discussion is a draft of a confidentiality policy with respect to third parties that is informed by psychoanalytic theory and clinical practice rather than by local legal jurisdiction or original disciplines' ethics codes.

Confidentiality↗
PubMed2003

[MR imaging of ano-perineal suppurations].

A good digital examination is usually sufficient for the diagnosis and the treatment planning of anal fistulae. Cross-sectional imaging techniques, however, can accurately identify deep abscesses and characterize complex fistulae. MRI is well suited for this examination, with almost no motion artifact, excellent contrast between muscles and fatty spaces, and multiplanar acquisition. A fistula starts from an internal opening in the digestive tube and can end in an abscess cavity or open at the skin at an external opening. The cryptoglandular anal fistulae (fistula-in-ano) are non-specific in origin and are usually simple, whereas specific fistulae are due to many diseases such as Crohn's disease, tuberculosis, trauma, radiation, colloid carcinoma, hidradenitis suppurative, actinomycosis or lymphoma and are often complex. MRI appears useful in the cases with recurrent fistulae, Crohn's disease, when the secondary orifice is atypically placed, during a multistep treatment for complex fistulae, or when an anal stenosis forbids a clinical or ultrasound examination. A good knowledge of the perineum anatomy is required for analysing the fistula tracts. The muscle planes separate fatty spaces which have an important role in the spread of the disease: sub-mucosal space, marginal space, intersphincteric space, postanal space of Courtney, supralevator space, and the two ischioanal spaces on both sides of the anal canal. The anal canal is surrounded by the ring-like internal sphincter, which continues the internal muscularis propria of the rectum, and the external sphincter, which is intermingled with the puborectalis muscle. We perform our MRI examination with an external phased array coil, and we place a cannula to identify the anal canal. The T2W sequences give the more interesting information, but the sequences with fat-suppression and gadolinium chelate injection are also very useful. The MRI examination allows the analysis of: 1) the location of the fistula tracts according to Park's classification, 2) the location of the internal opening, 3) the locations of the external opening(s), 4) the location of deep abscesses, 5) the long distance extensions, 6) the state of the ano-rectal wall and the perirectal spaces, 6) the damages of the anal sphincter.

Abscess↗
PubMed1994

Recent bed rest results and countermeasure development at NASA.

Bedrest studies of normal subjects provide opportunities to understand physiologic responses to supine posture and inactivity. Furthermore, head-down tilt has been a valuable procedure to investigate adaptation to microgravity and development of countermeasures to maintain the health and well-being of humans during space-flight. Recent bedrest experiments at NASA have ranged in duration from a few hours to 17 weeks. Acute studies of 6 degrees head-down tilt indicate that elevation of capillary blood pressure from 28 to 34 mm Hg and increased capillary perfusion in tissues of the head cause facial and intracranial edema. Intracranial pressure increases from 2 to 17 mm Hg going from upright posture to 6 degrees head-down tilt. Microvessels of the head have a low capacity to constrict and diminish local perfusion. Elevation of blood and tissue fluid pressures/flow in the head may also explain the higher headward bone density associated with long-term head-down tilt. These mechanistic studies of head-down tilt, along with a better understanding of the relative stresses involved with upright posture and lower body negative pressure, have facilitated development of suitable physiologic countermeasures to maintain astronaut health during microgravity. Presently no exercise hardware is available to provide a blood pressure gradient from head to feet in space. However, recent studies in our laboratory suggest that treadmill exercise using a graded lower-body compression suit and 100 mmHg lower body negative pressure provides equivalent or greater physiologic stress than similar upright exercise on Earth. Therefore, exercise within a lower body negative pressure chamber may provide a cost-effective and simple countermeasure to maintain the cardiovascular and neuro-musculoskeletal systems of astronauts during long-duration flight.

Bed Rest↗
PubMed1998

Venoconstrictive thigh cuffs impede fluid shifts during simulated microgravity.

BACKGROUND: This study determined the efficacy of venoconstrictive thigh cuffs, inflated to 50 mmHg, on impeding fluid redistributions during simulated microgravity. METHODS: There were 10 healthy male subjects who were exposed to a 2-h tilt protocol which started in the standing position, and was followed by 30 min supine, 30 min standing, 30 min supine, 30 min of -12 degrees head down tilt (HDT, to simulate microgravity), 15 min of HDT with venoconstrictive thigh cuffs inflated, a further 10 min of HDT, 5 min supine, and 10 min standing. To increase the sensitivity of the techniques in an Earth-based model, 12 degrees HDT was used to simulate microgravity effects on body fluid shifts. Volume changes were measured with anthropometric sleeve plethysmography. RESULTS: Transition to the various tilt positions resulted in concomitant decrements in leg volume (Stand [STD] to Supine [SUP], -3.0%; SUP to HDT, -2.0%). Inflation of the venoconstrictive thigh cuffs to 50 mmHg, during simulated microgravity, resulted in a significant 3.0% increase in leg volume from that seen in HDT (p < 0.01). No significant changes in systemic cardiovascular parameters were noted during cuff inflation. CONCLUSIONS: We conclude that venoconstrictive thigh cuffs, inflated to 50 mmHg for 15 min during 12 degrees HDT, can create a more Earth-like fluid distribution. Cuffs could potentially be used to ameliorate the symptoms of cephalad edema seen with space adaptation syndrome and to potentiate existing fluid volume countermeasure protocols.

Adult↗
PubMedDate not supplied

[Modification of a method for determining the cytotoxic activity of lymphocytes--natural killers in space experiments].

A space modification of a method for determining the cytotoxic activity of natural killers (NK) uses cultures of human lymphocytes and re-inoculated suspension of tumorous myeloblasts K-562. The 3H-uridine labeled target-cells fixated in 0.1 % formalin solution proved to be best suited to the conditions prohibiting regular recharge of cultural medium and utilization of radioactive agents. The following practical conclusions were made from the space-flown experiment: pre-launch procedures (lymphocyte isolation and delivery to the launch site) and time period till dock must not be longer than 5 days (1) and during transportation to the orbiting vehicle cell cultures must be kept at 18-20 degrees C (2). The modified method can be employed to study various aspects of cell interaction such as the NK ability to destroy target-cells in suspension cultured exposed in microgravity.

Antimicrobial Cationic Peptides↗
PubMedDate not supplied

U.S. manned space flight: the first twenty years, a biomedical status report.

In the last 20 years, the biomedical problems facing man in space have been brought into sharper focus. Space motion sickness is presently our most serious problem. Its etiology remains obscure, but the "sensory conflict" theory appears most plausible. No valid predictive tests of susceptibility exist and presently we must rely on medication for prevention or mitigation of symptoms. Adaptation/biofeedback techniques may prove useful. Cardiovascular "deconditioning" may be effectively attenuated by use of anti-g suits or plasma expanding techniques. Recent bedrest simulation studies would seem to indicate that concerns about chronically elevated central venous pressure during space flight are unfounded. The loss of red cell mass in space flight appears to be self-limited, independent of mission duration, and not of clinical concern, based on recent Soviet experiences. And finally, clodronate, a new diphosphonate effective in preventing hypercalciuria and negative calcium balance in normal human bedrested subjects, may prove effective in preventing or lessening skeletal mineral loss in space.

Adaptation, Physiological↗