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At least 127 records · Page 7Linked to original sources
PubMed1996

Microleakage of multi-step and simplified-step bonding systems.

PURPOSE: To measure and compare the microleakage of Class V resin composite restorations using the following three pairs of multi- and simplified-step dentin bonding systems (DBS): OptiBond vs. OptiBond FL, All-Bond 2 vs. One-Step, and Tenure vs. Tenure Quik. MATERIALS AND METHODS: V-shaped cavities were prepared in the mesial and distal surfaces of 30 extracted human mandibular molars with margins in both enamel and cementum, and randomly assigned into three equal groups of 10 each. All DBSs were applied strictly following manufacturers' specifications before three incremental layers of resin composite (Pertac-Hybrid) were applied in all cavities. Specimens were stored for 7 days in 37 degrees C water, thermocycled for 300 cycles between 5 degrees C and 55 degrees C, immersed in 0.5% basic fuchsin solution for 24 hours, and embedded in resin before being sectioned longitudinally in multiple sections. Dye solution penetration at the tooth/composite interface was scored from 0 to 4 under a microscope at x100 at both enamel (E) and cementum (C) margins. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests with alpha = 0.05. RESULTS: OptiBond FL and One-Step showed less microleakage at the cementum margins compared to their multi-step versions. At the enamel margins Tenure Quik showed less microleakage compared to Tenure, and none of the other DBSs tested showed significant dye penetration at that interface. All DBSs showed significantly less microleakage at the enamel margins compared to the cementum margins except for OptiBond FL and One-Step that did not show any significant dye penetration at the cementum margins as well.

Analysis of Variance↗
PubMed2005

A validation study of the WHO analgesic ladder: a two-step vs three-step strategy.

GOALS OF WORK: The aims of the present study were to verify whether an innovative therapeutic strategy for the treatment of mild-moderate chronic cancer pain, passing directly from step I to step III of the WHO analgesic ladder, is more effective than the traditional three-step strategy and to evaluate the tolerability and therapeutic index in both strategies. METHODS: Patients aged 18 years or older with multiple viscera or bone metastases or with locally advanced disease were randomized. Pain intensity was assessed using a 0-10 numerical rating scale based on four questions selected from the validated Italian version of the Brief Pain Inventory. Treatment-specific variables and other symptoms were recorded at baseline up to a maximum follow-up of 90 days per patient. RESULTS: Fifty-four patients were randomized onto the study, and pain intensity was assessed over a period of 2,649 days. The innovative treatment presented a statistically significant advantage over the traditional strategy in terms of the percentage of days with worst pain > or =5 (22.8 vs 28.6%, p < 0.001) and > or =7 (8.6 vs 11.2%, p = 0.023). Grades 3 and 4 anorexia and constipation were more frequently reported in the innovative strategy arm, although prophylactic laxative therapy was used less in this setting. CONCLUSIONS: Our preliminary data would seem to suggest that a direct move to the third step of the WHO analgesic ladder is feasible and could reduce some pain scores but also requires careful management of side effects.

Adult↗
PubMed2005

One-step percutaneous nephrolithotomy sheath versus standard two-step technique.

OBJECTIVES: Advances in technique and equipment have allowed urologists to perform percutaneous stone removal with increasing efficacy and decreasing complications. The procedure of choice for large renal calculi is percutaneous nephrolithotomy. At our institution, percutaneous access is achieved by a two-step process using either Amplatz dilators or placement of a high-pressure balloon catheter for tract dilation, followed by advancement of a sheath over the balloon. A novel device, the Pathway Access Sheath (PAS) has been developed that allows for balloon tract dilation and percutaneous access sheath placement in one simple step. METHODS: Our study population consisted of 21 patients, who were randomized to one of two arms. Of the 21 patients, 10 underwent standard two-step access using a high-pressure balloon catheter and 11 underwent percutaneous nephrolithotomy using the novel PAS. We compared the insertion time, blood loss, and cost between the two techniques. RESULTS: The average insertion time was shorter in the PAS group (3 minutes) compared with the high-pressure balloon catheter (5 minutes, 42 seconds); a difference that was statistically significant (P <0.01). The estimated blood loss and cost were similar between the two groups. The increased sheath flexibility of the PAS was noted to be an advantage in some patients. CONCLUSIONS: The results of our study have shown that a novel single-step renal access device is safe and efficacious and results in a shorter insertion time for percutaneous nephrolithotomy. Blood loss was less in the PAS group as well, although the difference was not statistically significant. Additional studies will establish whether this device will provide a new standard of obtaining renal access.

Adolescent↗
PubMed2000

Step by step filter based program for calculations of highly informative derivative curves

We have developed a microcomputer program, based on a recently described approach called step by step filter (SBSF), for calculation of derivative curves directly from spectra recorded as a function of wavelength. This program avoids the long wavelength attenuation featured at conventional method for derivative curves calculation, and in this extent could be very helpful for daily spectroscopy practice. The features of the SBSF program include: easy treatment of data through a windowed environment, calculating of both conventional and step by step filter derivatives, possibilities for selection of the mathematical conditions for smoothing and differentiation simultaneous plotting of the original curve and its derivative and a mouse pointer. Several examples from different branches of the molecular spectroscopy (absorption UV-VIS, CD and fluorescence) are provided and discussed in the terms of advantages of SBSF.

Journal Article↗
PubMed2002

Effects of headgear Herbst and mandibular step-by-step advancement versus conventional Herbst appliance and maximal jumping of the mandible.

The aims of this study were to compare dental and skeletal treatment changes in Class II division 1 malocclusions with two modes of maxillary control and two modes of bite-jumping. The subjects comprised Chinese children with severe Class II division 1 malocclusions, i.e. 21 consecutive subjects (13.4 +/- 1.4 years) treated with a headgear Herbst appliance and step-by-step advancement (HHSSA) of the mandible, and 24 consecutive subjects (13.2 +/- 1.4 years) treated with a 'conventional' Herbst appliance with maximal jumping (HMJ) of the mandible. Lateral cephalograms obtained at the start and end of treatment were analysed. The results showed that the improvement of the sagittal jaw relationship was significantly larger (2.9 mm; P < 0.001) in the HHSSA group than in the HMJ group due to the increased effect on the maxilla (-1.5 mm, P < 0.001) and the mandible (+1.4 mm, NS). There was no significant difference in the change in lower anterior face height, being 2.7 and 3.1 mm, respectively. The mandibular plane angle decreased significantly in the HHSSA group (-0.7 degree; P < 0.05) and increased insignificantly in the HMJ group (0.4 degree, NS), the difference being statistically significant (P < 0.01). The maxillary molars moved significantly more distally (1.1 mm, P < 0.05) and were intruded in the HHSSA group (-1.0 mm, P < 0.001) compared with a small extrusion in the HMJ group (+0.3 mm, NS), the difference being statistically significant (P < 0.001). There was no significant difference in the effect on the mandibular teeth. Treatment with HHSSA seems to result in a greater effect on the sagittal jaw relationship, improved vertical control and more maxillary molar movement. Mandibular anchorage loss was not reduced with step-by-step advancement of the mandible.

Adolescent↗
PubMed2004

Three-step versus single-step use of system B: evaluation of gutta-percha root canal fillings and their adaptation to the canal walls.

This study aimed to evaluate the quality of gutta-percha (GP) root canal fillings and their adaptation to the root canal walls, when the System B was used in three steps and a single step to fill three different split-tooth models. Each model was filled 10 times in two different ways. Group A: the System B plugger was used to fill the apical 3 mm of the canal in three steps, and then the Obtura II was used to backfill the rest of the canal. Group B: the System B plugger was inserted just once to a distance 3 mm short of the working length and then backfilled as in Group A. Replication of artificial depressions, presence of voids within the GP mass, and presence of spaces between the GP mass and the root canal walls were evaluated and scored. The individual scores of each parameter evaluated were compared between the two groups and statistically analyzed by use of the Mann-Whitney U test. Group A showed statistically significant (p < 0.05) better scores than Group B concerning the replication of artificial depressions and spaces between the GP mass and the canal walls. It was concluded that better adaptation of the GP mass to the canal walls in the apical third was obtained when the System B plugger was used in three steps.

Dental Marginal Adaptation↗
PubMed2005

Comparison of hearing screening programs between one step with transient evoked otoacoustic emissions (TEOAE) and two steps with TEOAE and automated auditory brainstem response.

OBJECTIVE: To compare the efficacy between one step with transient evoked otoacoustic emissions (TEOAE) and two steps with TEOAE and automated auditory brainstem response (AABR) in a newborn hearing screening program. We investigated their differences in referral rate, the accurate identification rate of congenital hearing loss (HL), and cost effectiveness. METHOD: From November 1998 to December 2004, a total of 21,273 healthy newborns were screened for HL in Mackay Memorial Hospital, Taipei. In the periods from November 1998 to January 2004 and from February 2004 to December 2004, the screening tools used were TEOAE alone (n = 18,260) and TEOAE plus AABR (n = 3,013), respectively. RESULTS: A statistically significant decrease of referral rate was achieved in the group using TEOAE and AABR as screening tools when compared with TEOAE alone (1.8% vs. 5.8%). The accurate identification rate of congenital HL was 0.45% in TEOAE protocol and 0.3% in TEOAE and AABR protocol, which was not statistically significant. The total direct costs per screening were 10.1 U.S. dollars for the program using TEOAE alone and 8.9 U.S. dollars for the TEOAE plus AABR program. The intangible cost, however, was much higher in the earlier program because of the higher referral rate. CONCLUSION: In terms of the efficacy of a hearing screening program using the one step TEOAE and two step TEOAE and AABR programs, the later significantly decreased the referral rate from 5.8% to 1.8%. No significant difference was noted between the accurate identification rates of congenital HL. The total costs, including expenditures and intangible cost, were lower in the protocol with TEOAE plus AABR.

Cost-Benefit Analysis↗
PubMed1984

Comparison of bone resorption at one-step and two-step mandibular endosseous implants in dogs.

Endosseous dental implants have been inserted into dog jaw bone following two different implantation principles. Using the two-step procedure, the implant is left submerged, covered by the mucoperiosteum for a healing period, before communication with the oral cavity is established. According to the one-step procedure, this communication is established peroperatively. In order to estimate radiographically the degree of bone resorption following the two-step as compared to the one-step procedure, the former was used on the right and the latter on the left side of the mandible in two dogs. Periodic identical intraoral radiographs revealed bone resorption in the neck area of all implants. After a 1-yr period with bilateral bridges, the vertical resorption varied between 3 and 5 mm. No difference was found between the two methods concerning this bone resorption. The observation seems to be contrary to the general opinion on the matter, and pertinent investigations with the present model will be performed in a human material.

Animals↗
PubMed2000

Stepping before standing: hip muscle function in stepping and standing balance after stroke.

OBJECTIVE: To compare the pattern of pelvic girdle muscle activation in normal subjects and hemiparetic patients while stepping and maintaining standing balance. DESIGN: Group comparison. METHOD: Seventeen patients who had regained the ability to walk after a single hemiparetic stroke were studied together with 16 normal controls. Median interval between stroke and testing was 17 months. Amplitude and onset latency of surface EMG activity in hip abductors and adductors were recorded in response to sideways pushes in either direction while standing. Similar recordings were made in the same subjects during gait initiation and a single stride. RESULTS: In the standing balance task, normal subjects resisted a sideways push to the left with the left gluteus medius (74 ms) and with the right adductor (111 ms), and vice versa. In hemiparetic patients, the amplitude of activity was reduced in the hemiparetic muscles, the onset latencies of which were delayed (gluteus medius 96 ms, adductor 144 ms). Contralateral, non-paretic, adductor activity was increased after a push towards the hemiparetic side of patients with stroke and the latency was normal (110 ms). During self initiated sideways weight shifts at gait initiation, hemiplegic muscle activation was impaired. By contrast, the pattern and peak amplitude of hip muscle activation in stepping was normal in both hemiparetic and non-hemiparetic muscles of the subjects with stroke. CONCLUSIONS: In ambulant patients with stroke, a normal pattern of activation of hemiparetic muscles is seen in stepping whereas the response of these muscles to a perturbation while standing remains grossly impaired and is compensated by increased activity of the contralateral muscles. This suggests that hemiparetic patients should be able to step before regaining standing balance.

Electromyography↗
PubMed2005

Least-squares algorithm for phase-stepping interferometry with an unknown relative step.

A pointwise least-squares phase-stepping algorithm with an unknown relative phase step is proposed. In phase-stepping interferometry the recorded temporal intensity sequence is a discrete sinusoidal signal biased by a direct-current component. Its value at a certain time can be predicted from its three past samples by use of a recursive formula. Based on this linear prediction property, an unbiased least-squares estimator is deduced to determine the relative phase step from a sequence of intensity values, and the result is used to evaluate the phase value. The validity and performance of this algorithm are verified by computer simulations.

Journal Article↗
PubMed2006

Lower-extremity bilateral differences during step-close and no-step countermovement jumps with concern for gender.

The goals of this investigation were to characterize gender differences in step-close (SC) and no-step (NS) countermovement jumps, examine biomechanical differences of the lead leg (LL) and trail leg (TL) during the SC jump, contrast the LL and TL of the SC to those of the NS jump, and determine whether bilateral asymmetries of the SC jump transfer to NS jump performance. The SC jump differs from the NS jump by a lead-in step that is continuous with the ensuing countermovement. Recreationally competitive volleyball players (12 men and 12 women) volunteered for the study. Three maximal-effort attempts in each condition were analyzed. Ground reaction forces were measured with force platforms and lower-extremity kinematics with optical capture. Ground reaction force as well as anatomical flexion and extension plane joint angle, moment, and power maximum (or minimum) and average values during the propulsion phase were analyzed with significance assessed at p < 0.05. Differences existed between the men and women in anthropometrics and jump height, as well as in many of the joint angles and body weight-normalized kinetic parameters, suggesting that women would benefit from increased strength and power at the ankle, knee, and hip. Differences also existed in many of the parameters between the LL and TL of the SC jump. Subjects jumped higher in the SC condition with greater demands placed on the LL, with the TL often acting similarly to its behavior in the NS condition. A few asymmetries of the LL and TL in the SC jump at the ankle and knee were also present in the NS jump. Strength and conditioning programs should include activities, such as plyometric jumps, that incorporate a step-close technique to optimize the development of this jump style. To minimize the development of functional asymmetries, the LL should be alternated by sets or repetitions.

Adolescent↗
PubMed1998

Is backward stepping over obstacles achieved through a simple temporal reversal of forward stepping?

The main purpose of the study was to examine whether backward stepping over obstacles was a simple temporal reversal of kinematic and muscle activation patterns found in forward obstacle avoidance. Obstacle avoidance was used as a probe to represent one aspect of walking over variable terrain. Kinematics, trajectories and muscle activation profiles for forward versus backward stepping over obstacles revealed that the simple reversal of locomotor patterns observed for level walking cannot be applied to obstacle avoidance. However, key kinematic data and limb trajectories for backward leading limb stepping were found to be similar to existing forward trailing limb data. Therefore, it appears that stepping over obstacles requires a complex upper level reorganization of the basic locomotor pattern based on biomechanical and sensory feedback.

Adult↗
PubMed1999

Possibilities of the method of step-by-step complication of ligand structure in studies of protein--nucleic acid interactions: mechanisms of functioning of some replication, repair, topoisomerization, and restriction enzymes.

X-Ray structure analysis is one of the most informative methods for investigation of enzymes. However, it does not provide quantitative estimation of the relative efficiency of formation of contacts revealed by this method, and when interpreting the data this does not allow taking into account the relative contribution of some specific and nonspecific interactions to the total affinity of nucleic acids (NA) to enzymes. This often results in unjustified overestimation of the role of specific enzyme--NA contacts in affinity and specificity of enzyme action. In recent years we have developed new approaches to analysis of the mechanisms of protein--nucleic acid interactions allowing quantitative estimation of the relative contribution of virtually every nucleotide unit (including individual structural elements) to the total affinity of enzymes to long DNA and RNA molecules. It is shown that the interaction between enzymes and NA on the molecular level can be successfully analyzed by the methods of synthesis and analysis, that is, step-by-step simplification or complication of the structure of a long NA-ligand. This approach allows the demonstration that complex formation including formation of contacts between enzymes and specific NA units can provide neither high affinity of the enzymes to NA nor the specificity of their action. Using a number of sequence-independent replication and repair enzymes specifically recognizing a modified unit in DNA and also some sequence-dependent topoisomerization and restriction enzymes as examples, it was shown that virtually all nucleotide units within the DNA binding cleft interact with the enzyme, and high affinity mainly (up to 5-7 of 7-10 orders of magnitude) is provided by many weak additive interactions between these enzymes and various structural elements of the individual NA nucleotide units. At the same time, the relative contribution of specific interactions to the total affinity of NA is rather small and does not exceed 1-2 orders of magnitude. Specificity of enzyme action is provided by the stages of the enzyme-dependent NA adaptation to the optimal conformation and directly of catalysis: kcat increases by 3-7 orders of magnitude when changing from nonspecific to specific NA. In the present work we summarized our experience in studies of enzymes by the method of step-by-step complication of the ligand structure and performed a detailed analysis of the features of this approach and its possibilities for the study of protein--nucleic acid interactions on the molecular level.

Binding Sites↗
PubMed1992

Factors affecting the oxygen cost of stepping on an electronic stepping ergometer.

The purposes of this study were to evaluate (a) the effects of step rate and upper body support on the VO2 and HR responses to fixed work rates on the StairMaster 4000 (SM), (b) the accuracy of the SM settings, and (c) how HR compared with that measured during grade-walking on a treadmill. Six subjects worked at a slow step rate for 6 min and then a faster step rate for the last 6 min of a 12-min test at SM settings of 4, 7, and 10 METs. Gas exchange and HR measurements were made at minutes 4-6 and 10-12. Variations in step rate had no effect on HR (P = 0.45) or VO2 (P = 0.84). The effect of using the arms and hands for support was studied using 6 subjects who worked for 12 min at 4, 7, and 10 METs; the first 6 min without support, and the second 6 min with support. Support resulted in lower HR (P = 0.017) and VO2 (P = 0.002) values at 10 METs. The measured MET values were about 20% lower than those specified by machine settings: True MET values = 0.556 + 0.745 (SM setting). Finally, at the same VO2, systematically higher (7-11 b.min-1) HR values were observed for the SM relative to the treadmill.

Adult↗
PubMed1992

Physiologic comparison and validation of Stairobic stepping with bench stepping.

To compare the oxygen cost of submaximal exercise on the Stairobic stepping (SS) machine with bench stepping (BS), 12 healthy men and women (mean age 23 years) underwent six different five minute exercise bouts that were randomly assigned. Tests were conducted using standard open circuit calorimetry. SS at 40 and 60 st/min was equal to BS at 20 st/min and SS at 80 st/min was equal to BS at 30 st/min for VE and RER. VO2 was equal at 20 st/min (BS) and 60 st/min (SS), and 30 st/min (BS) and 80 st/min (SS). Stairobic MET (SM) displayed values over-estimated actual MET (AM) values at the two lowest SS rates and under-estimated the AM value at the highest SS rate. Forty-eight observations of the MET response of SS were conducted and analyzed (BMDP2R) in a forward stepping solution. The multiple regression equation calculated for AM was: AM = -0.567 + -0.012 (WT) + 0.063 (rate) + 0.612 (SM) with an adjusted R2 of 0.82 and a SEE of 0.90. The physiologic cost of BS was approximately equal to SS at two to three times the BS rate of stepping.

Adult↗
PubMed2006

Tensile and shear bond strength evaluation of a total-etch three-step and two self-etching one-step dentin bonding systems.

PURPOSE: The aim of this study was to compare the bond strengths of two new self-etching one-step (Prompt L-Pop 2 and Adper Prompt L-pop) to a total-etch three-step dentin bonding system (Scotchbond Multipurpose Plus). MATERIALS AND METHODS: One hundred twenty human molars were randomly divided into 3 groups of 40 specimens each. Dentin surfaces of each group were bonded with either Scotchbond Multipurpose Plus (SMP), a three-step system, Prompt L-Pop 2 (PLP), or Adper Prompt L-Pop (APLP), two one-step bonding systems--according to manufacturers' recommendations. After adhesive application, a composite resin cylinder was incrementally built in a Teflon mold (5 mm high and 5 mm in diameter). The samples of each group were randomly divided into 2 subgroups of 20 samples each and were tested in a shear bond or in a tensile bond strength mode (crosshead speed 5 mm/min). Statistical analyses were performed with one-way ANOVA and Student's t-test. RESULTS: The significantly lowest shear and tensile bond strength values were obtained with APLP. PLP revealed higher shear bond strengths than APLP and SMP. There were no differences in tensile bond strengths between PLP and SMP (p < 0.05). CONCLUSION: The results of this in vitro study showed that the chemical modifications (adjunction of monomers and copolymers) of the self-etching all-in-one system APLP did not improve its mechanical properties.

Analysis of Variance↗
PubMed1990

[Treatment of patients with corticoid-dependent bronchial asthma by step-by-step intra-pulmonary administration of glucocorticoids].

The efficacy of a local step-by-step intrapulmonary and systemic administration of glucocorticosteroids (GCS) in 61 patients with corticoid dependent bronchial asthma was studied. A significantly earlier normalization of the basic clinical symptoms of exacerbation of the disease and an improvement of the external respiration function were revealed in the main group of patients, as compared to the controls. The method of a local step-by-step intrapulmonary administration of GCS made it possible to increase the treatment efficacy by bringing down the GCS dosage required to maintain++ remission and excluding complications caused during intrapulmonary injection of drugs to patients with corticoid dependent bronchial asthma.

Adult↗
PubMed1986

Effects of step-up and step-down heating on a transplantable murine tumor.

The effects of step-up (42----44 degrees sequence) and step-down (44----42 degrees sequence) heating were studied on a transplantable mammary adenocarcinoma of C3H/He mouse. Tumor-bearing legs were immersed in a water bath and the response to hyperthermia was evaluated in terms of the delay in tumor growth. Tumor growth was delayed greatly with increase in the duration of treatment with 44 degrees hyperthermia, whereas with 42 degrees hyperthermia of up to 180 min, tumor growth was delayed only slightly. The effects of step-up heating were similar to those of 44 degrees hyperthermia alone and the response was enhanced by a factor of 0.9-1.1 with the 60-min treatment at 42 degrees followed by treatment at 44 degrees. Thermal resistance developed when the preheating time at 42 degrees was longer than 30 min. On the other hand, the tumor response was markedly enhanced by step-down heating by a factor of 1.8-2.4 with the treatment at 44 degrees followed by 60-min treatment at 42 degrees. Since the enhancement factor for skin damage found previously was similar to that for the tumor, therapeutic gain cannot be expected by the use of these combined heat treatments.

Animals↗