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At least 721 records · Page 40Linked to original sources
PubMed2005

Extraction environment enhancement: critical evaluation of early socket healing in long-term barrier-protected extraction sockets.

Resorption and remodeling of the alveolar bone occurs after periodontal disease, trauma, or tooth extraction. Loss of the functional apparatus can have a deleterious effect on the ability to place endosseous root-form implants into prosthetically ideal locations. As a result, there has been a trend toward socket preservation at the time of extraction. However, there has been limited investigation with histologic verification of results on types of materials used to preserve or augment extraction sockets. Minimizing bone loss after extractions enables an implant to be placed in an ideal orientation surrounded by bone, thereby increasing the longevity of the implant and associated prosthesis. The case reports presented detail clinical and histological results during the 3 to 6 months after a bone maintenance procedure that used a nonexpanded polytetrafluoroethylene barrier placed over an extraction socket with no graft material at the time of tooth extraction.

Alveolar Bone Loss↗
PubMed1975

Electromyographic verification of viable muscle tissue following a double-pendulum flap procedure for surgical repair of bilateral cleft lip.

Five patients were seen in an electromyographic study of the double pendulum flap method of bilateral cleft lip repair. All five patients displayed active orbicularis oris muscle tissue. By bringing lateral lip segments to the center of the cleft, the double pendulum flap method restores muscular function and improves cosmetic appearance. This surgical procedure may be modified to be performed on other anomalies resulting from a discontinuity of muscular tissue.

Adolescent↗
PubMed2002

Agrypnia Excitata: a generalized overactivity syndrome and a useful concept in the neurophysiopathology of sleep.

OBJECTIVES: To analyse the clinicophysiological features of delirium tremens (DT), Morvan's fibrillary chorea (MC) and fatal familial insomnia (FFI) as representative of the new concept of Agrypnia Excitata (AE). METHODS: DT, MC and FFI were compared for their clinical and polysomnographic features and, for MC and FFI, post-mortem verification. RESULTS: DT, MC and FFI all display profound loss of slow-wave sleep (SWS) and abnormal rapid eye movement (REM) sleep with lack of muscular atonia and enacted dreams. Sleep spindles and K complexes are severely reduced. Motor overactivity is associated with increased sympathergic functions. Neuropathology discloses severe loss of neurons in the thalami and cingular areas in FFI, and leakage of antibodies in the thalamus in MC. CONCLUSIONS: Based on the similarities in DT, MC and FFI, we propose the new concept of AE as a clinical condition characterized by loss of SWS and abnormal REM sleep, associated with motor and autonomic sympathergic activation. AE is due to dysfunction of the thalamo-limbic system. Moreover, the preservation of light sleep in the face of severe loss of deep sleep in AE argues that 3 rather than the usually considered two (non REM and REM) independent states of sleep exist.

Humans↗
PubMed1998

Generation of a conditionally neo(r)-containing retroviral producer cell line: effects of neo(r) on retroviral titer and transgene expression.

We have developed a method for generating high-titer retroviral producer cell lines conditionally containing a neomycin resistance gene (neo(r)) based on the Cre/loxP system. For this, a bicistronic retroviral splicing vector carrying the green fluorescence protein (GFP) and a marker gene cassette consisting of internal ribosome entry site (IRES) and neo(r) flanked by loxP sites, was constructed and conveniently used to generate a G418 resistant vector producer cell line. Following titer determination and verification of the biological activity of the retroviral supernatants, the selectable expression cassette which was no longer required was excised from the provirus by transient Cre expression using an adenoviral vector. This strategy led to precise excision of neo(r) and generation of retroviral supernatants containing functional 'neo-less' retroviral particles without detrimental effects on the high vector titers found in the parental neo(r)-containing producer lines. GFP expression was significantly increased after the excision of neo(r), in both the producer lines and retrovirally transduced target cells. Reintroduction of neo(r) did not alter GFP expression, suggesting that the neo(r) gene and/or its gene product per se are not acting as a transcriptional silencer.

Adenoviridae↗
PubMed2003

Nervous system targets of RNA editing identified by comparative genomics.

An unknown number of precursor messenger RNAs undergo genetic recoding by modification of adenosine to inosine, a reaction catalyzed by the adenosine deaminases acting on RNA (ADARs). Discovery of these edited transcripts has always been serendipitous. Using comparative genomics, we identified a phylogenetic signature of RNA editing. We report the identification and experimental verification of 16 previously unknown ADAR target genes in the fruit fly Drosophila and one in humans-more than the sum total previously reported. All of these genes are involved in rapid electrical and chemical neurotransmission, and many of the edited sites recode conserved and functionally important amino acids. These results point to a pivotal role for RNA editing in nervous system function.

Adenosine↗
PubMed2005

RalA and RalB: antagonistic relatives in cancer cell migration.

The Ral family of small G proteins has been implicated in tumorigenesis, invasion, and metastasis. However, little emphasis has been placed on clarifying the individual roles of the two Ral proteins, RalA and RalB, in these processes in view of their high sequence homology. Here we analyze the separate contributions of RalA and RalB in regulating cell migration, a necessary component of the invasive phenotype, in two human cancer cell lines; UMUC-3, a bladder carcinoma line, and the prostate carcinoma line, DU145. Although inhibiting RalA protein expression by approximately 80% with two different small interfering RNA duplexes had no effect on migration, inhibiting RalB expression to the same extent with two different duplexes resulted in a marked reduction in migration. Inhibiting RalB expression did trigger a significant loss of actin cytoskeleton fibers in UMUC-3 that was not seen with inhibition of RalA expression. Interestingly, simultaneous inhibition of RalA and RalB expression had no effect on migration. However, dual inhibition of RalA and RalB expression in UMUC-3 did result in an almost total loss of actin fibers as well as a reduction in proliferation, particularly in reduced serum conditions. These results suggest that RalA and RalB have different roles in cell migration and that they may in fact act as antagonists with regard to this phenotype. As further verification of this hypothesis, we found that expression of constitutively active RalA inhibited migration, whereas expression of constitutively active RalB stimulated migration, consistent with this model. In summary, we present the first demonstration that despite their significant sequence homology, RalA and RalB have nonoverlapping and opposing functions in cancer cell migration but overlapping functions in cell growth.

Actins↗
PubMed2000

Cryptographic framework for document-objects resulting from multiparty collaborative transactions.

Multiparty transactional frameworks--i.e. Electronic Data Interchange (EDI) or Health Level (HL) 7--often result in composite documents which can be accurately modelled using hyperlinked document-objects. The structural complexity arising from multiauthor involvement and transaction-specific sequencing would be poorly handled by conventional digital signature schemes based on a single evaluation of a one-way hash function and asymmetric cryptography. In this paper we outline the generation of structure-specific authentication hash-trees for the the authentication of transactional document-objects, followed by asymmetric signature generation on the hash-tree value. Server-side multi-client signature verification would probably constitute the single most compute-intensive task, hence the motivation for our usage of the Rabin signature protocol which results in significantly reduced verification workloads compared to the more commonly applied Rivest-Shamir-Adleman (RSA) protocol. Data privacy is handled via symmetric encryption of message traffic using session-specific keys obtained through key-negotiation mechanisms based on discrete-logarithm cryptography. Individual client-to-server channels can be secured using a double key-pair variation of Diffie-Hellman (DH) key negotiation, usage of which also enables bidirectional node authentication. The reciprocal server-to-client multicast channel is secured through Burmester-Desmedt (BD) key-negotiation which enjoys significant advantages over the usual multiparty extensions to the DH protocol. The implementation of hash-tree signatures and bi/multidirectional key negotiation results in a comprehensive cryptographic framework for multiparty document-objects satisfying both authentication and data privacy requirements.

Computer Communication Networks↗
PubMed1980

[Severe ventricular arrhythmia following parenteral administration of vincamine. Predisposing factors in 6 cases].

Six patients developed ventricular arrhythmias with parenteral administration of vincamine. Direct intravenous injection was the mode of administration in 2 cases, intravenous infusion in 3 cases (one at very high dosage) and intramuscular injection in 1 case. The same signs of toxicity were observed in al patients:--5 patients had recorded attacks of "torsades de pointe", which recurred in 1 of them when the drug was restarted.--1 patient had syncope and, although an ECG was not recorded at the time, an ECG shortly afterwards showed a long QT interval and R/T ventricular extrasystoles. Symptoms were generally neurological in nature with syncope, cyanosis, and convulsions. Spontaneous regression was observed in 3 cases but in the others the drug had to be stopped and cardiopulmonary resuscitation instituted. None of our patients died of their arrhythmia. In some patients a predisposing factor was found:--metabolic: hypokalaemia (1 case), moderate reduction of potassium pool (1 case), severe reduction of calcium pool (1 case);--pharmacological: previous treatment with fenoxidil (1 case), thioridazine (1 case);--cardiac: congenital long QT interval (Romano-Ward) (1 case), revealed by vincamine administration. Chronic obstructive airways disease with right ventricular strain and atrial fibrillation (1 case) which might have predisposed the patient to "torsades de pointes". Three patients had no predisposing factors apart from their age. "Torsades de pointes" occurred in a pacemaker patient, but pacemaker function was normal. These six cases may be grouped with the other ten or so cases of vincamine toxicity already reported; they carry and additional warning on the use of intramuscular vincamine. Vincamine toxicity is probably a direct effect on the myocardial cells. This fact merits verification by further electrophysiological studies.

Aged↗
PubMed2003

Experimental verification and simulation of negative index of refraction using Snell's law.

We report the results of a Snell's law experiment on a negative index of refraction material in free space from 12.6 to 13.2 GHz. Numerical simulations using Maxwell's equations solvers show good agreement with the experimental results, confirming the existence of negative index of refraction materials. The index of refraction is a function of frequency. At 12.6 GHz we measure and compute the real part of the index of refraction to be -1.05. The measurements and simulations of the electromagnetic field profiles were performed at distances of 14lambda and 28lambda from the sample; the fields were also computed at 100lambda.

Journal Article↗
PubMed1996

Dosimetric verification of intensity-modulated fields.

The optimization of intensity distributions and the delivery of intensity-modulated treatments with dynamic multi-leaf collimators (MLC) offer important improvements to three-dimensional conformal radiotherapy. In this study, a nine-beam intensity-modulated prostate plan was generated using the inverse radiotherapy technique. The resulting fluence profiles were converted into dynamic MLC leaf motions as functions of monitor units. The leaf motion pattern data were then transferred to the MLC control computer and were used to guide the motions of the leaves during irradiation. To verify that the dose distribution predicted by the optimization and planning systems was actually delivered, a homogeneous polystyrene phantom was irradiated with each of the nine intensity-modulated beams incident normally on the phantom. For each exposure, a radiographic film was placed normal to the beam in the phantom to record the deposited dose. The films were calibrated and scanned to generate 2-D isodose distributions. The dose was also calculated by convolving the incident fluence pattern with pencil beams. The measured and calculated dose distributions were compared and found to have discrepancies in excess of 5% of the central axis dose. The source of discrepancies was suspected to be the rounded edges of the leaves and the scattered radiation from the various components of the collimation system. After approximate corrections were made for these effects, the agreement between the two dose distributions was within 2%. We also studied the impact of the "tongue-and-groove" effect on dynamic MLC treatments and showed that it is possible to render this effect inconsequential by appropriately synchronizing leaf motions. This study also demonstrated that accurate and rapid delivery of realistic intensity-modulated plans is feasible using a dynamic multi-leaf collimator.

Biophysical Phenomena↗
PubMed1988

[A model of the coronary vascular bed and its verification by a physiological experiment].

We analysed the relationship between artery pressure (AP) and coronary flow (F) in the canine coronary bed, using an electrical analog model of the coronary circulation. The model contained a capacitance of epicardial vessels, input and terminal resistances, diode, and the number of e.m.f., simulated the intramyocardial pressure and zero-flow pressure. These e.m.f. are assumed to be a linear functions of left ventricular and aortic pressure. The value of coronary blood flow was calculated from experimental curves of AP and LVP and setting parameters. Good agreement was obtained between theoretical and experimental curves of coronary blood flow.

Animals↗
PubMed1986

[Two-year clinical experience with Mevamatic 3--development of a verification and protocol system for irradiation units].

Since 1983 the computerized record and verify system Mevamatic 3 was tested in connection with the linear accelerator Mevatron 77 (Siemens Company). In consequence of the software development the handling of the system was improved for the clinical routine with the result of a fully utilizable system. The topics of this report are the description of the hardware, the functions of the system, the software development and some possibilities for improvements in the future.

Germany, West↗
PubMed1996

Adaptive changes in trabecular architecture in relation to functional strain patterns and disuse.

Principal strains and their orientation, determined from in vivo and in situ strains recorded from the lateral cortical surface of the calcaneus of potoroos (a small marsupial) during treadmill exercise and tension applied via the Achilles tendon, were compared with the underlying trabecular architecture and its alignment to test Wolff's "trajectorial theory" of trabecular alignment. In vivo and in situ principal compressive strains (-800 to -2000 mu e) were found to be aligned (mean 161 +/- 7 degrees) close to the preferred alignment (160 degrees) of underlying trabeculae within the calcaneal metaphysis [a second trabecular arcade was closely aligned (70 degrees) with the direction (71 degrees) of principal tensile strain]. This finding represents quantitative verification of Wolff's trajectorial theory of trabecular alignment. These trabecular alignments, as measured by trabecular anisotropy (TbAn, the ratio of horizontal: vertical intercepts), remained unchanged (p > 0.05) after 8 weeks of disuse. However, trabecular bone volume fraction (BV/TV, -35%), trabecular thickness (TbTh, -25%), and trabecular number (TbN, -16%) were reduced for the tenotomized calcaneii relative to their contralateral controls (p < 0.001 to < 0.003). The reduction in trabecular number was associated with a corresponding increase in trabecular spacing (TbSp, +30%). Together, these results suggest that once trabecular alignment is established during growth (along the directions of principal strain during locomotion), it is not altered when functional strains are removed.

Adaptation, Physiological↗
PubMed1975

Intellectual functioning in a sample of institutionalized narcotic addicts.

The Shipley-Hartford scales were given to 1,980 institutionalized addicts. Overall, results showed that addict IQs are about normal. Of all demographic variables analyzed, only education explained an appreciable proportion of the variance in scores (12%). There were indications that a relatively high number of addicts may have some intellectual impairment (41%). The latter results await further verification.

Adolescent↗
PubMed2000

Experimental verification of quark-hadron duality

A newly obtained sample of inclusive electron-nucleon scattering data has been analyzed for precision tests of quark-hadron duality. The data are in the nucleon resonance region, and span the range 0. 3<Q2<5.0 (GeV/c)(2). Duality is observed both in limited and extended regions around the prominent resonance enhancements. Higher twist contributions to the F2 structure function are found to be small on average, even in the low Q2 regime of approximately 0.5 (GeV/c)(2). Using duality, an average scaling curve is obtained. In all cases, duality appears to be a nontrivial property of the nucleon structure function.

Journal Article↗
PubMed2000

Using the Rorschach properly in practice and research.

Proper use of the Rorschach Inkblot Method (RIM) in practice and research requires (a) well-founded expectations concerning what the RIM should be expected to do, and (b) appropriate methods for examining its validity in achieving the purposes for which it is intended. The RIM is a personality-assessment instrument, and its validity should be judged from its substantial correlations with observed behaviors that are conceptually linked to personality processes. Knowledge about personality functioning gleaned from Rorschach data may contribute to diagnostic formulations, but associations between Rorschach indices and psychometrically shaky DSM diagnostic categories have little bearing on the utility of the instrument for achieving its intended purposes. Adequate conceptual formulation of this kind is as necessary as solid empirical verification in the development and use of psychological assessment instruments.

Humans↗
PubMed2026

Development and Validation of a Predictive Model for Identification of Cognitive Impairment Risk in Older Adults with Subjective Cognitive Decline&#xff1a;A Longitudinal Study.

BACKGROUND: Subjective cognitive decline (SCD) is a transitional state between objective cognitive impairment and cognitively intact mental status, providing a critical window for implementing preventive interventions to delay objective cognitive decline. AIMS: We aimed to develop a predictive model for SCD progression in older adults with mild cognitive impairment (MCI). This model will facilitate the identification of risk factors and establishment of targeted interventions for community-based SCD management. METHODS: Data from the China Health and Retirement Longitudinal Study (CHARLS) was utilized in this study, extracting 18 indicators. Potential predictors selected through univariate Cox regression and LASSO regression analyses were sequentially incorporated into a multivariable Cox regression model. A nomogram was constructed to establish a predictive model. Model validation encompassed Area Under Curve (AUC) metrics for discriminative capacity, complemented by quantitative assessments using calibration curve analysis for precision verification and decision curve analysis (DCA) for clinical utility evaluation. RESULTS: A total of 1099 older adults with SCD were included in the final analysis, of whom 114 (10.3%) developed MCI. Multivariable Cox regression identified residence, marital status, educational level, social participation, gait speed, and baseline cognitive function. The model demonstrated time-dependent AUC values of 0.885, 0.830, 0.839, and 0.836 in the training set when evaluating discriminative capacity at 2-, 4-, 7-, and 9-year, respectively. The predictive model showed excellent predictive ability according to AUC, calibration curve, and DCA. CONCLUSIONS: A predictive model was created to estimate the risk of developing MCI in older individuals with SCD, offering clinician-actionable intervention benchmarks for preventive care.

Humans↗
PubMed2003

Optical-CT gel-dosimetry I: basic investigations.

Comprehensive verification of the intricate dose distributions associated with advanced radiation treatments is now an immediate and substantial problem. The task is challenging using traditional dosimeters because of restrictions to point measurements (ion chambers, diodes, TLD, etc.) or planar measurements (film). In essence, rapid advances in the technology to deliver radiation treatments have not been paralleled by corresponding advances in the ability to verify these treatments. A potential solution has emerged in the form of water equivalent three dimensional (3D) gel-dosimetry. In this paper we present basic characterization and performance studies of a prototype optical-CT scanning system developed in our laboratory. An analysis of the potential role or scope of gel dosimetry, in relation to other dosimeters, and to verification across the spectrum of therapeutic techniques is also given. The characterization studies enabled the determination of nominal operating conditions for optical-CT scanning. "Finger" phantoms are introduced as a powerful and flexible tool for the investigation of optical-CT performance. The modulation-transfer function (MTF) of the system is determined to be better than 10% out to 1 mm(-1), confirming sub-mm imaging ability. System performance is demonstrated by the acquisition of a 1 x 1 x 1 mm3 dataset through the dose distribution delivered by an x-ray lens that focuses x rays in the energy range 40-80 KeV. This 3D measurement would be extremely difficult to achieve with other dosimetry techniques and highlights some of the strengths of gel dosimetry. Finally, an optical Monte Carlo model is introduced and shown to have potential to model light transport through gel-dosimetry systems, and to provide a tool for the study and optimization of optical-CT gel dosimetry. The model utilizes Mie scattering theory and requires knowledge of the variation of the particle size distribution with dose. The latter was determined here using the technique of dynamic-light-scattering.

Algorithms↗