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At least 1,657 records · Page 92Linked to original sources

PubMed2002

Robotic inhibition assay for determination of HMG-CoA reductase inhibitors in human plasma.

The cholesterol-lowering drug simvastatin (SIMV, Zocor reduced heart attacks by 42% in patients who had high cholesterol levels and suffered from heart disease. Upon oral administration, SIMV is quickly hydrolyzed to its beta-hydroxyacid and other acid metabolites, which are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase. A Tecan-based enzyme inhibition assay has been developed to improve the existing Zymark-based assay for the determination of both active and total concentrations of HMG-CoA reductase inhibitors in human plasma. A Tecan Genesis 200 robotic workstation equipped with eight probes and customized hardware was utilized to achieve higher sample throughput and improve assay reproducibility and mechanical stability. The developed enzyme inhibition assay was validated over two concentration ranges of 0.4-20 ng equivalent/mL, and 2-50 ng equivalent/mL. Intra- and interday precision data (coefficient of variation (CV)) for both concentration ranges were less than 9%, with an accuracy of 93-107%. The interday precision for the determination of quality control (QC) samples was less than 2% and 8%, respectively. The respective interday QC accuracy values were 93-103% and 97-104%. Good linearity across the two concentration ranges was observed, with acceptable reproducibility. This improved enzyme inhibition assay has been utilized to analyze human plasma samples from several clinical studies.

Humans↗

PubMed2005

Internet-based robotic laser scissors and tweezers microscopy.

We have engineered a robotic laser ablation and tweezers microscope that can be operated via the internet using most internet accessible devices, including laptops, desktop computers, and personal data assistants (PDAs). The system affords individual investigators the ability to conduct micromanipulation experiments (cell surgery or trapping) from remote locations (i.e., between the US and Australia). This system greatly expands the availability of complex and expensive research technologies via investigator-networking over the internet. It serves as a model for other "internet-friendly" technologies leading to large scale networking and data-sharing between investigators, groups, and institutions on a global scale. The system offers three unique features: (1) the freedom to operate the system from any internet-capable computer, (2) the ability to image, ablate, and/or trap cells and their organelles by "remote-control," and (3) the security and convenience of controlling the system in the laboratory on the user's own personal computer and not on the host machine. Four "proof of principle" experiments were conducted: (1) precise control of microscope movement and live cell visualization, (2) subcellular microsurgery on the microtubule organizing center of live cells viewed under phase contrast and fluorescence microscopy, (3) precise targeting of multiple sites within single red blood cells, and (4) optical trapping of 10 microm diameter polystyrene microspheres.

Internet↗

PubMed1993

Comparison of the flashlamp pulsed dye laser with the argon tunable dye laser with robotized handpiece for facial telangiectasia.

This prospective study compares the efficacy, side effects, and patient acceptance of the flashlamp pulsed dye laser (FPDL) with the argon tunable dye laser with robotized handpiece (ATDL/H) for facial telangiectasias. Seventeen adult patients with bilaterally symmetric facial telangiectasias were enrolled. The right cheek on each patient was treated in one session with the FPDL at a fluence of 6.0-6.75 J/cm2 and a spot size of 5 mm. The left cheek was treated at the same session with the ATDL/H at a power of 1 W, a fluence of 26-27 J/cm2, and a hexagonal treatment area of 13 mm (127 individual 1 mm spots grouped mechanically by the handpiece). Patients were evaluated subjectively and by the investigators at 2, 4, and 6 weeks for blistering, swelling, bruising, changes in pigment, scarring, overall efficacy, and patient preference. Average treatment times were 5.4 minutes for FPDL and 9.4 minutes for ATDL/H. Blistering, crusting, and discomfort were completely resolved on both sides by week 2 in all patients. Bruising occurred in all patients with FPDL but had resolved in 62.5% of patients at 2 weeks and 100% at 4 weeks. There was no bruising with ATDL/H. Postinflammatory hyperpigmentation was much more prominent with FPDL but had resolved in 88% of cases by week 6. As rated by the investigators 100% of the FPDL treated areas showed excellent clearing of telangiectasias, compared with 47% of ATDL/H treated areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Pseudomosaicism, true mosaicism, and maternal cell contamination in amniotic fluid processed with in situ culture and robotic harvesting.

This study was designed to test the usefulness of the common definitions for maternal cell contamination, true mosaicism, and pseudomosaicism for amniotic fluid specimens processed by in situ culture and robotic harvesting. We prospectively studied 4309 consecutive amniotic fluid specimens processed with these methods and found that 0.84 per cent had maternal cell contamination, 0.28 per cent had true mosaicism, and 5.4 per cent had pseudomosaicism. Although the frequencies of maternal cell contamination and true mosaicism were comparable to those in similar published studies, the frequency of pseudomosaicism was more than twice as high as that in previous reports. This finding is most likely not due to the method, but rather to a more accurate estimate of the actual frequency of pseudomosaicism in amniotic fluid cultures than reported heretofore. Follow-up clinical information was available on 72 per cent of the cases. In three cases of true mosaicism involving structural anomalies, the results of cytogenetic follow-up studies on the neonates were normal. None of the pseudomosaic cases involving trisomy 8, 13, 18, or 21; triple X; or monosomy X were associated with newborns who had birth defects.

Amniocentesis↗

PubMed1999

Robot predators in virtual ecologies: the importance of memory in mimicry studies.

An important means of investigating gains and losses to prey caused by mimicry is through mathematical or computer constructs which represent and explore limited aspects of mimicry situations. Such studies use virtual predators which are usually simple automata, 'robots' that, through simple rules, vary virtual attack rates on virtual insect prey. In this paper I consider the effect of variations in predator memory and learning on mimicry dynamics. When there is mimicry between unequally noxious prey, the way that memory is modelled is shown to be crucial. If forgetting rates are fixed, an increase in the density of the least defended prey produces monotonic gains or losses in protection. However, if forgetting rate is inversely related in some way to degree of noxiousness of the prey then attack rates initially rise with the density of the least defended prey, reach a cusp and then fall. I show that the generation of this highly unconventional up-down result appears to be independent of variations in learning rate. This work shows how sensitive the predictions of virtual predators may be to relatively small changes in behavioural rules. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1980

Anthropomorphic robotics. I. Representing mechanical complexity.

A study of the fundamental principles upon which manipulation dexterity is based cannot help mixing robotic and neurophysiological concepts. A preliminary step in this study consists of trying to understand the complexity of manipulation dynamics. Though complexity shows itself in the massive number of elements of kinematic and dynamic equations, the fundamental simplicity of the underlying mechanical laws suggests to look for a structure, particularly from the computational point of view. Accordingly, a working computational model is proposed that organizes the massive computational load into a structure which is composed of a small number of computational units and lends itself to parallel computation.

Arm↗

PubMed2002

[Image fusion, virtual reality, robotics and navigation. Effects on surgical practice].

In the new minimally invasive surgical era, virtual reality, robotics, and image merging have become topics on their own, offering the potential to revolutionize current surgical treatment and assessment. Improved patient care in the digital age seems to be the primary impetus for continued efforts in the field of telesurgery. The progress in endoscopic surgery with regard to telesurgery is manifested by digitization of the pre-, intra-, and postoperative interaction with the patients' surgical disease via computer system integration: so-called Computer Assisted Surgery (CAS). The preoperative assessment can be improved by 3D organ reconstruction, as in virtual colonoscopy or cholangiography, and by planning and practicing surgery using virtual or simulated organs. When integrating all of the data recorded during this preoperative stage, an enhanced reality can be made possible to improve intra-operative patient interactions. CAS allows for increased three-dimensional accuracy, improved precision and the reproducibility of procedures. The ability to store the actions of the surgeon as digitized information also allows for universal, rapid distribution: i.e., the surgeon's activity can be transmitted to the other side of the operating room or to a remote site via high-speed communications links, as was recently demonstrated by our own team during the Lindbergh operation. Furthermore, the surgeon will be able to share his expertise and skill through teleconsultation and telemanipulation, bringing the patient closer to the expert surgical team through electronic means and opening the way to advanced and continuous surgical learning. Finally, for postoperative interaction, virtual reality and simulation can provide us with 4 dimensional images, time being the fourth dimension. This should allow physicians to have a better idea of the disease process in evolution, and treatment modifications based on this view can be anticipated. We are presently determining the accuracy and efficacy of 4 dimensional imaging compared to conventional evaluations.

Computer Systems↗

PubMed2000

Induction of putative tumor-suppressing genes in Rat-1 fibroblasts by oncogenic Raf-1 as evidenced by robot-assisted complex hybridization.

The growth factor receptor-dependent protein kinase Raf-1 is activated by GTP-bound Ras, thereby activating the mitogen-activated protein kinase pathway. To study the role of Raf in transformation we transduced Rat-1 cells with a tetracycline-regulatable retroviral vector encoding the constitutively active oncogenic C-terminal fragment of the human Raf-1 protein. Using subtractive hybridization of mRNAs from induced and noninduced cells and robot-assisted screening by complex hybridization, Raf-induced genes with various different characteristics of induction were investigated. Among the strongly induced genes were those involved in carcinogenesis such as metalloproteinases 3, 10 and 13, cathepsin L, ornithine decarboxylase, and putative tumor-suppressing genes such as monocyte chemoattracting protein 1, interferon-induced protein 10, a recently identified 2'-5' oligoadenylate synthetase-like protein, and plasminogen activator inhibitor type 2. Other components of the plasminogen activator system were not induced. Plasminogen activator inhibitor type 2 is a down-regulator of the proteolytic cascade consisting of various metalloproteinases, some of which are induced by a carboxy-terminal Raf mutant (RafCT). In conclusion, RafCT induces factors which act in a conflicting manner in respect of carcinogenesis, especially within the proteolytic system of the extracellular matrix.

Animals↗

PubMed2005

Multiview robotic microscope reveals the in-plane kinematics of amphibian neurulation.

A new robotic microscope system, called the Frogatron 3000, was developed to collect time-lapse images from arbitrary viewing angles over the surface of live embryos. Embryos are mounted at the center of a horizontal, fluid-filled, cylindrical glass chamber around which a camera with special optics traverses. To hold them at the center of the chamber and revolve them about a vertical axis, the embryos are placed on the end of a small vertical glass tube that is rotated under computer control. To demonstrate operation of the system, it was used to capture time-lapse images of developing axolotl (amphibian) embryos from 63 viewing angles during the process of neurulation and the in-plane kinematics of the epithelia visible at the center of each view was calculated. The motions of points on the surface of the embryo were determined by digital tracking of their natural surface texture, and a least-squares algorithm was developed to calculate the deformation-rate tensor from the motions of these surface points. Principal strain rates and directions were extracted from this tensor using decomposition and eigenvector techniques. The highest observed principal true strain rate was 28 +/- 5% per hour, along the midline of the neural plate during developmental stage 14, while the greatest contractile true strain rate was--35 +/- 5% per hour, normal to the embryo midline during stage 15.

Algorithms↗

PubMed2004

Robotic cardiac surgery at Epworth hospital.

Epworth Hospital is the first in the southern hemisphere to acquire the da Vinci Robot to facilitate minimally invasive cardiac surgery. Applications for this new technology include mitral valve repair, atrial septal defect closure, single coronary artery bypass graft to coronary arteries on the front of the heart, ablative surgery for atrial fibrillation and insertion of epicardial pacemaker electrodes. A team of surgeons from the Epworth Hospital have trained at East Carolina University (ECU) Greenville, North Carolina, USA; including surgeons, anesthetists, perfusionist and nurses. Following this, during a week in March, a proctoring surgeon from the USA, Dr. Wiley Nifong, assisted the Epworth team with their initial seven operations, which all proceeded without incident. The initial operative times were longer than the standard surgery, although with additional experience, now totalling 24 patients in all, these times have shortened considerably. The experience to date is summarized as an Addendum to this manuscript.

Journal Article↗

PubMed1998

Influence of loading duration on the start-up friction in synovial joints: measurements using a robotic system.

OBJECTIVE: To determine how much and why static load influences friction in synovial joints. DESIGN: Start-up coefficient of friction in canine stifles was measured after different duration of static load. BACKGROUND: Previous investigators have shown that friction of cartilage on cartilage contact configurations sharply increases with stationary load duration. This phenomenon has not been confirmed in the entire synovial joint. METHODS:: A system to measure joint friction was designed using a robotic arm. Ten canine stifles from six animals were used. Start-up friction of the femoral condyle on the tibial plateau and femoral condyle on glass plate contact configurations was measured. The glass plate was chosen as a rigid surface where ploughing effect cannot occur. RESULTS: The mean value of the start-up frictional coefficient from femoral condyle on tibial plateau was 0.112 (SD 0.005) at 0 s stationary loading, and sharply increased with the stationary loading duration to 0.313 (SD 0.095) at 1800 s. Those from femoral condyles on glass plate were 0.005 (SD 0.003) at 0 s and 0.457 (SD 0.128) at 1800 s. CONCLUSIONS: Friction in synovial joints sharply increases with duration under static load. The ploughing effect on this increase is slight in friction in canine stifles. RELEVANCE: The lubrication mechanism is worth investigating to understand the pathology of joint diseases. Determining friction behaviour is necessary for the investigation of the lubrication mechanism.

Journal Article↗

PubMed1996

A Kendama Learning Robot Based on Bi-directional Theory.

A general theory of movement-pattern perception based on bi-directional theory for sensory-motor integration can be used for motion capture and learning by watching in robotics. We demonstrate our methods using the game of Kendama, executed by the SARCOS Dextrous Slave Arm, which has a very similar kinematic structure to the human arm. Three ingredients have to be integrated for the successful execution of this task. The ingredients are (1) to extract via-points from a human movement trajectory using a forward-inverse relaxation model, (2) to treat via-points as a control variable while reconstructing the desired trajectory from all the via-points, and (3) to modify the via-points for successful execution. In order to test the validity of the via-point representation, we utilized a numerical model of the SARCOS arm, and examined the behavior of the system under several conditions. Copyright 1996 Elsevier Science Ltd.

Journal Article↗

PubMed1998

Precision Requirements for Closed-Loop Kinematic Robotic Control Using Linear Local Mappings.

Neural networks are approximation techniques that can be characterized by adaptability rather than by precision. For feedback systems, high precision can still be acquired in presence of errors. Within a general iterative framework of closed-loop kinematic robotic control using linear local modeling, the inverse Jacobian matrix error and the maximum length of the displacement for which the linear model is valid are computed. They guarantee convergence of the feedback loop. The error bounds are computed for our manipulator. The theoretical results are validated by simulation.

Journal Article↗

PubMed2001

Robotic enzyme amplification: a comparison of some kinetic properties of bovine liver, Candida utilis and Proteus sp. glutamic dehydrogenases.

NADP(H)-specific Bakers yeast glucose 6-phosphate dehydrogenase (BYG6PDH) was paired, in turn, with each of three different source glutamate dehydrogenases (GDHs): NAD(P)-specific bovine liver (BLGDH), NADP-specific Candida utilis (CUGDH) and NADP-specific Proteus sp. (PSGDH) to constitute three enzyme cycling systems; (i) BYG6PDH/BLGDH; (ii) BYG6PDH/CUGDH; and (iii) BYG6PDH/PSGDH. When incorporated into an enzymatic cycling/amplification system for NAD kinase and run on a centrifugal fast analyzer (CFA), the microbial source enzyme CUGDH gave rise to a seven-fold greater amplification rate [21.5 x 10(3) cycles-1 (cph)] relative to that realized (3 x 10(3) cph) using the BYG6PDH/BLGDH cycling pair previously reported. Either of these cycling systems can be used as a flexible and general-purpose module for robotic amplification and data collection of NADP(H) linked enzymes as a user's requirements dictate. Although the BYG6PDH/PSGDH cycling pair produced a respectable cycling rate (14.4 x 10(3) cph), for reasons discussed the PSGDH enzyme was not considered a suitable replacement for BLGDH in an NADP(H) cycling system.

Animals↗

PubMed2005

Robotic sequential analysis of a library of metalloporphyrins as electrocatalysts for voltammetric nitric oxide sensors.

A library of 83 metalloporphyrins with varying substitution pattern at the meso-position of the porphyrins and different central metal ions in the core region has been synthesized in small quantities using a parallel synthesis strategy. By means of a specially designed electrochemical robotic device integrating a 96-well microtitre plate and an easily movable assembly of working, counter and reference electrodes, the different porphyrins were automatically applied in sequence to an in-well electrochemical preparation and testing of NO sensors. Screening the entire compound collection suggested initial considerations concerning the influence of varied functionalities of the metalloporphyrins on their electrocatalytic properties for the oxidation of NO and helped to identify the quality of the investigated catalyst candidates. As compared to manually performed quality tests, the proposed strategy of automation has advantages in convenience, rapidity and especially reproducibility avoiding any inaccuracies introduced by manually performing all steps of the complex sensor formation and testing sequence.

Animals↗

PubMed2006

Rendezvous-guidance trajectory planning for robotic dynamic obstacle avoidance and interception.

This correspondence presents a novel online trajectory-planning method for the autonomous robotic interception of moving targets in the presence of dynamic obstacles, i.e., position and velocity matching (also referred to as rendezvous). The proposed time-optimal interception method is a hybrid algorithm that augments a novel rendezvous-guidance (RG) technique with the velocity-obstacle approach, for obstacle avoidance, first reported by Fiorini and Shiller. The obstacle-avoidance algorithm itself could not be used in its original form and had to be modified to ensure that the online planned path deviates minimally from the one generated by the RG algorithm. Extensive simulation and experimental analyses, some of which are reported in this correspondence, have clearly demonstrated the tangible time efficiency of the proposed interception method.

Letter↗

PubMed1989

Use of robotics to dispense culture media.

Liquid and agar-containing media can be aseptically dispensed by a laboratory robot. Five errors occurred during the filling of 700 tubes with medium; four of these were due to imperfections of the screw-threaded caps of the culture tubes. The mean volume dispensed was 14.8 ml (standard deviation, 0.5; n = 50) when the system was set to deliver 15 ml.

Journal Article↗

PubMed2004

Use of robotized DNA isolation and real-time PCR to quantify and identify close correlation between levels of Neisseria meningitidis DNA and lipopolysaccharides in plasma and cerebrospinal fluid from patients with systemic meningococcal disease.

The present study, using robotized DNA isolation and quantitative PCR based on the Neisseria meningitidis-specific capsular transport A gene, demonstrates the ease, rapidity, specificity, and sensitivity of quantifying neisserial DNA in plasma (n = 65) and cerebrospinal fluid (CSF) (n = 12) from patients with systemic meningococcal disease. We found a close correlation between the levels of neisserial DNA and lipopolysaccharides in plasma (r = 0.905) and in CSF (r = 0.964). The median concentration of neisserial DNA in plasma in 23 patients with persistent shock was 2 x 10(7) copies/ml, versus <10(3) copies/ml in 42 nonshock patients. Furthermore, quantitative PCR made possible estimates of the total number of meningococci in plasma, as opposed to conventional blood cultures, suggesting about 1,000 dead meningococci for every viable bacterium. Finally, with logistic regression analyses, neisserial DNA may predict a patient's disease severity and outcome at hospital admission. The number of meningococci in plasma and CSF appears to be the main determinant of the lipopolysaccharide levels, clinical presentation, and outcome.

DNA, Bacterial↗