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At least 109 records · Page 6Linked to original sources
PubMed2000

Mucogingival interceptive surgery of buccally-erupted premolars in patients scheduled for orthodontic treatment. I. A 7-year longitudinal study.

BACKGROUND: Mucogingival interceptive therapy in patients with buccally erupting teeth is performed to prevent the ectopic permanent tooth from developing periodontal lesions. The keratinized tissue entrapped between the erupting tooth and the deciduous tooth is retained to maintain a satisfactory width of the gingiva for the permanent tooth. The aim of the present study on buccally-erupted premolars scheduled for orthodontics was to evaluate the keratinized tissue width 3 months, 2 years, and 7 years subsequent to mucogingival interceptive therapy and orthodontic treatment. METHODS: Twenty-nine patients participated. Three different surgical techniques were used according to specific indications. Eight patients were treated with double pedicle flaps (DPF), 10 patients with apically positioned flaps (APF), and 11 with free gingival grafts (FGG). RESULTS: The amount of keratinized tissue on the treated (test) sites was not significantly less than on the control (untreated) sites showing normally erupting premolars at all observation periods. All 3 surgical procedures appeared to be effective in saving the keratinized tissue for the permanent tooth. Preoperative periodontal parameters such as gingival width, probing depth, and bleeding on probing significantly influenced the outcome 3 months after surgery (P <0.01). CONCLUSIONS: Mucogingival interceptive surgery is an effective approach to conserve the keratinized buccal gingiva of ectopically erupting premolars.

Adolescent↗
PubMed2003

Variability of larval identification characters of exotic Aedes albopictus (Skuse) intercepted in Darwin, Northern Territory.

There is no morphological identification key to satisfactorily distinguish between the larvae of Aedes (Stegomyia) species with special consideration to endemic and exotic species in Australia. Difficulty in differentiation between exotic Aedes (Stegomyia) albopictus (Skuse) and Aedes (Stegomyia) scutellaris Walker has been described previously. Aedes (Stegomyia) larvae were collected during an interception from an overseas vessel in Darwin, Northern Territory, and link bred. The adults were identified as Ae. albopictus. The larval skins and larvae were used to describe the variation in hair features of larval segment VII that are used to identify Ae. albopictus. The median hair number of hair 1-VII was three, whereas the description in Huang's identification key states four. The median of hair 2-VII was one, confirming Huang. However, the variability was higher than described by Huang and nearly half of the specimens showed different hair numbers on both sides. Individual specimens are therefore not clearly distinguished from other members of the Aedes (Stegomyia) scutellaris group. This paper also describes the detection, elimination and surveillance procedures following the interception. These were successful in preventing the establishment of exotic Ae. albopictus in the Northern Territory following the interception.

Aedes↗
PubMed2002

Perception of acceleration with short presentation times: can acceleration be used in interception?

To investigate whether visual judgments of acceleration could be used for intercepting moving targets, we determined how well subjects can detect acceleration when the presentation time is short. In a differential judgment task, two dots were presented successively. One dot accelerated and the other decelerated. Subjects had to indicate which of the two accelerated. In an absolute judgment task, subjects had to adjust the motion of a dot so that it appeared to move at a constant velocity. The results for the two tasks were similar. For most subjects, we could determine a detection threshold even when the presentation time was only 300 msec. However, an analysis of these thresholds suggests that subjects did not detect the acceleration itself but that they detected that a target had accelerated on the basis of the change in velocity between the beginning and the end of the presentation. A change of about 25% was needed to detect acceleration with reasonable confidence. Perhaps the simplest use of acceleration for interception consists of distinguishing between acceleration and deceleration of the optic projection of an approaching ball to determine whether one has to run backward or forward to catch it. We examined the results of a real ball-catching task (Oudejans, Michaels, & Bakker, 1997) and found that subjects reacted before acceleration could have been detected. We conclude that acceleration is not used in this simple manner to intercept moving targets.

Humans↗
PubMed1981

Interception by post-coital IUD insertion.

After the development of postcoital hormonal interception, the postcoital use of IUDs to prevent pregnancy was proposed by Tatum. The major advantage of this treatment is that it avoids the use of the usual massive dose of estrogens (a very effective postcoital method) which is associated with nausea and vomiting. This is the 1st method to be effective up to 5 days after exposure, 3 days more than the estrogen treatment. It may also provide long-term contraception in women who wish to continue using the IUD. A major disadvantage of postcoital IUD use is that IUD insertion can produce serious complications if a patient has a vaginal or venereal infection or an asymptomatic cervicitis or even pelvic inflammatory disease (PID). After proper physical examination, suitable patients are selected from those requesting postcoital treatment. Cases involving rape are mostly excluded from these services; but, if they present early, proper work up and treatment can be performed within the time span of 5 days available for this method and it will still be possible to fit a postcoital IUD. The potential risk of future infertility should be considered as PID rates in nulliparous IUD users are up to 7 times higher than in nonusers. Young nulliparous, sexually active women--especially of the lower socioeconomic strata--are identified as high-risk patients. Over 70% of women requesting interception are nulliparous. Clients asking for postcoital insertion should be informed of its potential risk, as women under 25 years of age are more prone to infection. The risk of septic abortion exists if an IUD is inserted into a gravid uterus due to pregnancy resulting from unreported previous sexual intercourse. Septic abortion is a life-threatening condition. Out of several series, no pregnancies are reported in the month of treatment. The IUD preferred is the Multiload copper IUD or the copper T; the highest expulsion rate proved the Copper-7 Gravigard (Cu-7) inefficient. In suitable circumstances, the IUD can be the 1st choice in postcoital interception.

Age Factors↗
PubMed1979

The functional compensation: an interceptive procedure in the mixed dentition.

Functional compensation, like the morphologic one which accompanies it, is to be encountered naturally in each system or organ. It facilitates the performance of the required activities in spite of the defectiveness of one or more of their biocomponents. If the pathologic forms of compensation or simply their perturbing effects are noticed early enough, deleterious and irreversible effects on growth and development of the orofacial zone may be avoided. Instead of simply supervising dental evolution or limiting intervention to early procedures (extractions) until the time for corrective treatment, we propose functional interception. Inducing a therapeutic compensation by removable appliances, this therapy aims to modify the equilibrium of displaying forces and to favor a more physiologic alveolar and sutural growth. The proposed appliances are able to intervene in the postural and dynamic position of the mobile organs in the oral cavity. They compensate their action; that is, they correct, complete, or replace it. The bimaxillary appliance is called bioactivator "biprax". Based simultaneously on the principles of the activator and bionator, it exploits a normal display of the two praxisms-speech and deglutition. Being worn day and night, it is able to guide efficiently the evolution of dental, alveolar, and even basal relationships. Its interceptive use does not interfere in any way with the onset of a corrective treatment in the adult dentition.

Activator Appliances↗
PubMed2002

The role of prevention and simple interceptive measures in reducing the need for orthodontic treatment.

The purpose of the interceptive orthodontic treatment is to eliminate or reduce the need for treatment in the permanent dentition. The major advantage of such a treatment may also be that it is technically simple and relatively cheap, compared to comprehensive treatment with full fixed appliances. The need for interceptive measures to avoid adverse occlusal and dental consequences, which are effects of the early loss of primary molars and nonnutritive sucking habits, is discussed. The need for prevention and early intervention in patients with anterior open bites, posterior functional crossbites and signs of ectopic erupting canines is also discussed.

Humans↗
PubMed2005

Preventive and interceptive orthodontic treatment needs of an inner-city group of 6- and 9-year-old Canadian children.

OBJECTIVE: Early recognition of developing malocclusions and the potential for uncomplicated orthodontic treatment procedures can minimize or eliminate future costly treatment. This study was designed to assess the potential for this approach in children living in a limited-income environment. A modified index for preventive and interceptive orthodontic needs (IPION) was used to determine the need for such treatment in schoolchildren aged 6 and 9 years. METHODS: Two calibrated examiners examined each child independently and assessed several components of his or her occlusion, including molar relationship, crossbite, open bite, overbite and overjet. Dental variables such as presence of caries and early loss of teeth were also noted. Informed consent was obtained and all children present at school on the day of the field study were included. A total of 395 children were divided into 2 groups, aged 6 and 9 years. RESULTS: A high prevalence of caries in the deciduous dentition (30.4% for 6 year olds; 20.6% for 9 year olds) and early loss of primary teeth (11.9% for 6 year olds; 29.4% for 9 year olds) was observed. A large percentage of children had crossbite in the anterior or posterior segments, or both. Open bites were also a common finding. Future orthodontic problems were identified in 28% of this population by using the modified IPION. No statistically significant differences (p > 0.05) were found between sexes or age groups using the chi2 test. CONCLUSIONS: Most of the developing malocclusions identified in this study would be amenable to interceptive orthodontics, consisting of space maintenance, crossbite correction and arch expansion.

Child↗
PubMed1993

Direct interception of mutagens and carcinogens by biomolecules.

Five points are emphasized: 1. Chemical interception and mere physical exclusion of mutagens and carcinogens constitute the major means by which mutations in cellular DNA are prevented. DNA repair processes comprise critical, but relatively minor, modes of genetic protection. 2. Disruption of a mutagen-interception defense mechanism can lead to substantial increases in mutagenesis and can preordain sites to eventual tumor formation. 3. Quantitation of the relative contributions of various blocking molecules is often simplified by the fact that protection can be calculated merely through knowledge of the measured concentration of the antimutagen and its rate of reaction with specific mutagens as measured in straightforward in vitro tests. 4. Two recently recognized defensive molecules, carnosine and ergothioneine, are put ++forward as examples of interesting chemical interceptor molecules. 5. Essentially all antimutagens are in fact "double-edged swords." Situations can be artificially constructed that can lead to generation of toxic species from molecules that are normally antimutagens; in isolated cases some of these interactions can be pictured as having deleterious consequences in vivo. This may be one reason why a number of important antimutagens are often sequestered, either in different tissues or by binding to dispensable macromolecules.

Animals↗
PubMed1993

Extracellular interception of mutagens.

Extracellular interception of mutagens by excreted enzymes or by chemical agents that react with or bind to formed mutagens provides an important means of defense against chemical mutagens/carcinogens. Kada and Shimoi have classified molecules that function in this manner as "desmutagens," and many of them are natural cellular metabolites. Among the specific mechanisms that such agents may employ are: prevention of the activation of "promutagens" to mutagens; stimulation of enzymes (e.g., glutathione-S-transferase) that catalyze the binding/inactivation of damaging electrophiles; direct binding and concomitant inactivation of promutagens or mutagens; interference with uptake of mutagens into cells; etc. De Flora and Ramel have provided an excellent discussion of the mechanisms of these agents and a proposed classification scheme. Drawing on work from our own laboratories and other recent examples in the literature, several examples of mechanistic approaches to these studies using natural plant-derived materials, e.g., humic acid, Glycyrrhiza glabra extract, glutathione, and bioflavonoids, are also described. Antioxidants and agents that conjugate electrophiles will be among the modes of action described for obtaining the goal of intercepting mutagens/carcinogens.

Animals↗
PubMed1997

Manual interception of moving targets. II. On-line control of overlapping submovements.

We studied the kinematic characteristics of arm movements and their relation to a stimulus moving with a wide range of velocity and acceleration. The target traveled at constant acceleration, constant deceleration, or constant velocity for 0.5-2.0 s, until it arrived at a location where it was required to be intercepted. For fast moving targets, subjects produced single movements with symmetrical, bell-shaped velocity profiles. In contrast, for slowly moving targets, hand velocity profiles displayed multiple peaks, which suggests a control mechanism that produces a series of discrete submovements according to characteristics of target motion. To analyze how temporal and spatial aspects of these submovements are influenced by target motion, we decomposed the vertical hand velocity profiles into bell-shaped velocity pulses according to the minimum-jerk model. The number of submovements was roughly proportional to the movement time, resulting in a relatively constant submovement frequency (approximately 2.5 Hz). On the other hand, the submovement onset asynchrony showed significantly more variability than the intersubmovement interval, indicating that the submovement onset was delayed more following a submovement with a longer duration. Examination of submovement amplitude and its relation to target motion revealed that the subjects achieved interception mainly by producing a series of submovements that would keep the displacement of the hand proportional to the first-order estimate of target position at the end of each submovement along the axis of hand movement. Finally, we did not find any evidence that information regarding target acceleration is properly utilized in the production of submovements.

Adult↗
PubMed2001

Intercepting a moving target: effects of temporal precision constraints and movement amplitude.

The effects of temporal precision constraints and movement amplitude on performance of an interceptive aiming task were examined. Participants were required to strike a moving target object with a "bat" by moving the bat along a straight path (constrained by a linear slide) perpendicular to the path of the target. Temporal precision constraints were defined in terms of the time period (or window) within which contact with the target was possible. Three time windows were used (approx. 35, 50 and 65 ms) and these were achieved either by manipulating the size of the bat (experiment 1a), the size of the target (experiment 1b) or the speed of the target (experiment 2). In all experiments, movement time (MT) increased in proportion to movement amplitude but was only affected by differences in the temporal precision constraint if this was achieved by variation in the target's speed. In this case the MT was approximately inversely proportional to target speed. Peak movement speed was affected by temporal accuracy constraints in all three experiments: participants reached higher speeds when the temporal precision required was greater. These results are discussed with reference to the speed-accuracy trade-off observed for temporally constrained aiming movements. It is suggested that the MT and speed of interceptive aiming movements may be understood as responses to the spatiotemporal constraints of the task.

Acceleration↗
PubMed2002

Temporal precision of interceptive action: differential effects of target size and speed.

The duration of movements made to intercept moving targets decreases and movement speed increases when interception requires greater temporal precision. Changes in target size and target speed can have the same effect on required temporal precision, but the response to these changes differs: changes in target speed elicit larger changes in response speed. A possible explanation is that people attempt to strike the target in a central zone that does not vary much with variation in physical target size: the "effective size" of the target is relatively constant over changes in physical size. Three experiments are reported that test this idea. Participants performed two tasks: (1). strike a moving target with a bat moved perpendicular to the path of the target; (2). press on a force transducer when the target was in a location where it could be struck by the bat. Target speed was varied and target size held constant in experiment 1. Target speed and size were co-varied in experiment 2, keeping the required temporal precision constant. Target size was varied and target speed held constant in experiment 3 to give the same temporal precision as experiment 1. Duration of hitting movements decreased and maximum movement speed increased with increases in target speed and/or temporal precision requirements in all experiments. The effects were largest in experiment 1 and smallest in experiment 3. Analysis of a measure of effective target size (standard deviation of strike locations on the target) failed to support the hypothesis that performance differences could be explained in terms of effective size rather than actual physical size. In the pressing task, participants produced greater peak forces and shorter force pulses when the temporal precision required was greater, showing that the response to increasing temporal precision generalizes to different responses. It is concluded that target size and target speed have independent effects on performance.

Adolescent↗
PubMed2004

Coordinating degrees of freedom during interceptive actions in children.

The aim of the experiment was to examine how children coordinate the degrees of freedom of the arm and trunk when performing interceptive actions that correspond to daily life activities. For that purpose, children were required to reach and grasp a stationary ball while standing (condition C1), a stationary ball while walking (C2), and a moving ball while standing (C3). The resulting movements were measured in world-centered and body-centered coordinates, and then subjected to three-dimensional kinematic analysis. The different coordinate frames of reference were used to determine the interaction between arm and trunk movements. Children adapted their coordination in the two moving conditions (C2 and C3) by decelerating longer towards the ball and exhibiting more interaction between the arm and trunk movements than in the stationary condition (C1). These results indicate that, like adult participants, children adapt to the constraints imposed by complex, interceptive actions by recruiting additional degrees of freedom of the trunk, which are coordinated with the hand to produce a movement that preserves an appropriate level of impact at hand/object collision.

Adaptation, Physiological↗
PubMed2006

Postural adjustments and bearing angle use in interceptive actions.

The experiment investigates the effect of ball velocity and walking direction on the adherence to the bearing angle (BA) strategy in adults. Adult participants (N=12) approached a moving ball in order to manually intercept it at a predefined target area. Results revealed that during locomotion the BA strategy was implemented, but on reaching the point of interception, this strategy broke down and the BA strategy of the wrist compensated for the movement requirements relative to the ball velocity and approach angle. Larger deviations from the BA occurred when the angle of approach was decreased and when the ball velocity increased. When the BA strategy was adhered to, postural adjustments were reduced. Increased movements occurred in a proximal-distal direction with an increasing approach angle and a faster ball velocity.

Adaptation, Physiological↗
PubMed2007

Lateral ball interception: hand movements during linear ball trajectories.

Part of understanding how acts are coordinated is identifying the information that guides movements. In the case of catching a ball within arm's reach, that identification has been complicated by empirical disparities concerning hand-movement reversals during catching. Jacobs and Michaels found unilateral reversals in a paradigm in which balls swung down in an arc; this implicated a particular optical variable, the ratio of lateral velocity to expansion velocity. Montagne et al. reported bilateral reversals when balls approached along a linear trajectory, which implicated a different variable, lateral ball position. The research reported here attempted to replicate Montagne et al.'s findings. In Experiment 1, participants caught balls rolling toward them across a table, under full lighting using monocular or binocular viewing; in Experiment 2, participants caught luminous balls with a luminous glove in an otherwise dark room. Using Montagne et al.'s criterion, we observed no movement reversals in any condition, though some aspects of hand movements suggested the relevance of lateral ball position. The results of Experiment 3, which asked perceivers to indicate only where rods pointed, suggested that lateral position effects were a bias that is unrelated to interception. The ratio of lateral velocity to expansion appears to be a better variable for explaining hand trajectories in lateral interception.

Adolescent↗
PubMed1998

Monocular and binocular control of human interceptive movements.

Previous work in our laboratory has demonstrated that binocular vision makes an important contribution to skilled reaching and grasping movements directed at static targets. In the present study we examine the contribution of binocular vision to interceptive reaching movements. We monitored such movements using a high-resolution, opto-electronic recording device (WATSMART), while subjects attempted to catch balls projected at them. No differences were found between monocular and binocular viewing conditions using this paradigm - either with respect to the velocity profiles or trajectories of the reaches. Moreover, the grasp was not affected by the type of vision available. It appears, then, that the moving targets provide adequate monocular depth and direction information (on the basis of optic flow) for the control of skilled interceptive movements directed at them. In addition, the time to achieve maximum grip aperture was constant across the trials - a finding consistent with the use of a time-to-contact variable derived from optic flow information. Finally, the transport component of prehension was found to be affected by certain variables that have, in the past, been thought to exclusively affect the grasp component of prehension, whereas the grasp component of prehension was affected by factors that have traditionally been thought to affect only the transport component.

Adult↗
PubMed1980

STS 557 as an interceptive in rodents and baboons.

Studies with mice, rats, guinea pigs and baboons were undertaken to define the interceptive action of the new progestin STS 557 (17 alpha -cyanomethyl-17 beta-hydroxy-estra-4.9(10)-diene-3-one) and to compare it with other progestins used in oral contraceptives. STS 557, norethindrone and norethindrone acetate reduced deciduoma formation as well as the number of implantations in mice and rats. Chlormadinone acetate and levonorgestrel when administered at the appropriate dose could not prevent early pregnancy or deciduoma formation. But in contrast to STS 557, levonorgestrel maintained early pregnancy in ovariectomized rats. On the other hand, STS 557 was ineffective as a postcoital agent in guinea pigs. When 0.4 mg STS 557 was orally administered to 37 female baboons 3 or 6 h after the mating period, only one pregnancy occurred in a total of 60 cycles investigated (controls: 11 pregnancies in 12 cycles investigated). The results are discussed in view of the development of an interceptive method based on STS 557.

Animals↗
PubMed1991

Pregnancy interceptive efficacy and biological profile of 3-amino-6,7-dimethoxy-1H-pyrazolo [3,4-b] quinoline (compound 85/83) in rodents.

Administration of compound 85/83 during the peri- and post-implantation period intercepted pregnancy in hamster and guinea pig by parenteral route and in hamster by oral route also. The m.e.d. for hamster and guinea pig was 10 and 20 mg/kg, respectively; lower doses were less effective. Restricting the administration to early post-implantation schedule interrupted pregnancy partially in both species. The compound was, however, ineffective in rat and in the pre-implantation schedule (days 1-4 post-coitum) in hamster. When tested in vitro on growing trophoblasts at 13.8 x 10(-5) M concentration, it prevented growth and caused degeneration of the cells within 24 h; lower concentration (9.2 x 10(-5) M) was less effective. The compound was found to be devoid of estrogenic, antiestrogenic, progestational and antiprogestational properties in conventional bioassays. In hormone competition assays, its relative binding affinity (RBA) to estrogen receptor was negligible (0.002% of estradiol-17 beta), while for uterine cytosol progesterone receptors in rabbit and hamster was 0.06 and 0.08% of progesterone, respectively. The compound 85/83 appears to intercept pregnancy by interfering with development of trophoblast cells.

Administration, Oral↗