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At least 1,171 records · Page 65Linked to original sources

PubMed1989

Effects of two gutta-percha formulations and one zinc oxide-eugenol and Canada balsam mixture on human blood monocytes and lymphocytes.

In this study we performed an in vitro assay of the effects of two gutta-percha formulations and one zinc oxide-eugenol and Canada balsam-based endodontic material on the behavior of a mixed cell population of human monocytes and lymphocytes. Cells were cultured either in direct contact with or near experimental samples of Ultrafil, standard gutta-percha cones or Endoseal and the inhibitory effects of these materials upon cell attachment and spreading on test surfaces were analyzed. Ultrafil and the standard gutta-percha cones showed little or no adverse effects, whereas the inhibitory effects of Endoseal appeared to be severe. There were statistically significant differences between the results obtained from both Ultrafil and gutta-percha cones and those obtained from Endoseal. Differences between all tested materials and their respective controls were also statistically significant.

Balsams↗

PubMed1997

Power Doppler US of the normal prepubertal testis: does it live up to its promises?

PURPOSE: To assess whether power Doppler ultrasound (US) improves the detection of flow in normal prepubertal testes. MATERIALS AND METHODS: Seventy-two normal testes of 38 prepubertal boys (age range, 2 weeks to 12.5 years) were scanned with color and power Doppler US (7-MHz transducer). The two modalities were compared subjectively to determine which one was more sensitive for detection of flow. Only reproducible intratesticular flow signals were considered positive; capsular flow was disregarded. RESULTS: Power Doppler US depicted flow in 50 testes (69%), while color Doppler US depicted flow in 47 testes (65%, not statistically significant). Power and color Doppler US combined depicted flow in 57 testes (79%), which was significant when compared with color Doppler US alone (P = .002). Detection of flow was subjectively easier with power Doppler US in 10 of 72 testes, while it was easier with color Doppler US in 14 of 72 testes. Motion artifacts were greater with power Doppler US. CONCLUSION: Power Doppler US was equally sensitive as conventional color Doppler US in the detection of flow in normal prepubertal testes. Combining both modalities improved detection of flow in 14% of cases and may be useful in excluding torsion in children. For a positive preoperative diagnosis of torsion in children, radionuclide scintigraphy remains the imaging modality of choice.

Artifacts↗

PubMed2001

The floating shoulder: a biomechanical basis for classification and management.

BACKGROUND: The floating shoulder (ipsilateral fractures of the clavicular shaft and the scapular neck) is thought to be an unstable injury pattern requiring operative stabilization in most instances. This recommendation has been made with little biomechanical data to support it. The purpose of this study was to determine the osseous and ligamentous contributions to the stability of experimentally created scapular neck fractures in a cadaver model. METHODS: Standardized scapular neck fractures were made in twelve fresh-frozen human cadaveric shoulders. Each specimen was mounted in a specially designed testing apparatus and secured to a standard materials testing device. In group 1 (six shoulders), resistance to medial displacement was determined following sequential creation of an ipsilateral clavicular fracture, coracoacromial ligament disruption, and acromioclavicular capsular disruption. In group 2 (six shoulders), resistance to medial displacement was determined following sequential sectioning of the coracoacromial and coracoclavicular ligaments. RESULTS: The average measured force for all specimens (groups 1 and 2) after scapular neck fracture was 183 +/- 3.3 N (range, 166 to 203 N). The addition of a clavicular fracture (group 1) resulted in an average measured force of 128 +/- 10.5 N (range, 83 to 153 N), which corresponds to only a 30% loss of stability. Subsequent sectioning of the coracoacromial and acromioclavicular capsular ligaments yielded an average force of 126 +/- 9.1 N (range, 114 to 144 N), a 31% loss of stability, and 0 N, a complete loss of stability, respectively. Sectioning of the coracoacromial and coracoclavicular ligaments after scapular neck fracture (group 2) resulted in an average force of 103 +/- 8.4 N (range, 89 to 118 N), a 44% loss of stability, and 0 N, a complete loss of stability, respectively. CONCLUSIONS: Ipsilateral fractures of the scapular neck and the clavicular shaft do not produce a floating shoulder without additional disruption of the coracoacromial and acromioclavicular capsular ligaments. These and other unstable combined injury patterns are likely to be accompanied by substantial medial displacement of the glenoid fragment.

Aged↗

PubMed1979

Material effects in shear-induced hemolysis.

A rotating-disk apparatus for shearing blood was employed to compare 22 materials for their tendency to cause hemolysis during standardized low-stress (130 dynes/cm2 maximum) laminar flow conditions. Rigid plastics, hydrogels, and carbons were among the materials tested. Time-independent ranking of the materials was possible for 75% of the data; these rankings correlated linearly (for polymers) with the critical surface tension gammac over the range 20--46 dyne/cm, with low gammac being associated with low hemolysis. Surface morphology was also found to influence hemolysis. Roughness in the 1--15 micron range had a distinct effect on hemolysis kinetics for polyethylene surfaces. This suggest that failure to find time-independence in 25% of the material rankings can be attributed to inadequate control of the roughness variable. It also emphasizes the importance of surface morphology, as well as surface chemistry, as a biocompatibility parameter.

Acrylamides↗

PubMed1975

Potentially thrombogenic materials in factor IX concentrates.

Factor XI concentrates manufactured from human plasma and intended for therapeutic infsuion in man have been suspected for some time of being potentially thrombogenic. In the current studies, assays were carried out in vitro and in vivo for potentially thrombognic materials. It was possible to rank the various materials tested according to the amount of thromboninic material detected. For concentrates not containing heparin, there was substantial agreement between the in vivo and in vitro assays, with a coefficient of correlation of 0.77. There was no correlation between the assays for thrombogenicity and the antithrombin III content. We conclude that many presently availabel concentrates of Factor IX contain substantial amounts of potentially thrombogenic enzymes, and that this fact must be considered in arriving at the decision whether or not to use them therapeutically.

Animals↗

PubMedDate not supplied

[Language characterization in the X-fragile syndrome: a review study].

BACKGROUND: X-Fragile Syndrome. AIM: To compile information about the language, cognitive and behavior alterations in the X-Fragile Syndrome, using the results of previously published studies and to present the standardized instruments used as testing materials. CONCLUSION: studies used formal and informal testing to assess language. The results present variability regarding the linguistic deficits, which are influenced by the level of the cognitive deficit and behavior alterations. Alterations of the oral praxes and of speech articulation are also expected.

Cognition Disorders↗

PubMed2005

Mechanical assessment of effects of grape seed proanthocyanidins extract on tibial bone diaphysis in rats.

We studied the effects of grape seed proanthocyanidins extract (GSPE) given as a ratio of 3 mg in 100 g in a standard diet, on the tibial bone diaphysis in low-calcium fed rats. Measurements of bone density, mineral content, geometry, and bone strength using peripheral quantitative computed tomography (pQCT). Further, the whole tibia bones were tested for mechanical resistance using a material-testing machine, and mineral elements were also determined. Forty male Wistar rats, 5 weeks old, were divided into control (Co), low-calcium diet (LC), low-calcium diet . standard diet (LCS), and low-calcium diet . standard diet with supplementary GSPE (LCSG) groups. We found no significant differences in body weight among the 4 groups, whereas all of the bone parameters in LC were significantly lower than those in Co (p<0.01, except in periosteal perimeter (Peri) p<0.05). The cortical bone mineral content (CtBMC), cortical bone density (CtvBMD) and Peri in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). All bone parameters in LCSG were significantly higher than those in LC (p<0.01, except in Peri, and stress strain index to reference axis x (xSSI) p<0.05)). In addition, Ca, P, and Zn contents in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). Our results suggest that GSPE included in a diet mixture with calcium has a beneficial effect on bone formation and bone strength for the treatment of bone debility caused by a low level of calcium.

Animals↗

PubMed1989

[Observation with SEM on the displacement of mucosal surface in process of denture fabrication].

The process of denture fabrication entails a series of steps that begin with impression-taking. Dimensional accuracy and displacement of surface repeatability affect results in these individual steps. Although changes in individual materials have already been measured in the past, there has been almost no measurement up to now of denture fabrication up to the denture base, using the mucous membrane as the standard and then measuring changes in the displacement of surface repeatability for each step. Noticing this lack, the authors used a Scanning Electron Microscope (SEM), presently the only non-contact measuring instrument that can be used, and measured changes at the different stages including the mucous membrane, the impression materials, the plaster and the resin. A drying process is required for the mucous membrane, and such a process can cause changes in the mucous membrane which is the basis of measurement. For this reason, the authors used Araldite, a product from Ciba-Geigy AG, as a replica material and made replicas for all the test materials, using the replicas for measurement. Results were as follows: 1. Araldite was used as the replica material, thus making it possible with the SEM to observe changes in the displacement of surface repeatability at the individual stages. 2. Major changes in the accuracy of surface were observed during impression-taking and in the period of moving from the impression material to the plaster. 3. During high-power observation with the SEM, the fine bumps on the surface of the plaster and resin disappeared and the surfaces became smooth. This is believed to be the result of the separating agent and heat.

Dental Impression Materials↗

PubMed1980

Pathogenic yeast-like fungi in meat products.

100 samples of sausage and ham (cut in fine slices) were examined to find out whether meat products can harbour yeast-like fungi pathogenic for man. Pieces of the test material were placed in a sterile Petri dish containing 1 ml distilled water and incubated at 26 degrees C for 2 days. The colonies grown on the material were identified by international standard methods, tested for extracellular proteolytic activity and serotypes. Experimentally infected meat products were studied culturally and histologically (PAS stain). 14 out of the 100 samples examined were found to contain Candida parapsilosis and 1 C. tropicalis. In vitro, extracellular proteolytic activity was found in 54.5% of the C. parapsilosis isolates. By serotyping, 2 of the isolates wree found to be related with serotype A and 8 with serotype B of C. albicans. The strains isolated from the blood of 27 patients, in part of them, identity of serotype and proteolysing activity was established. In the experimentally infected meat products, C. albicans showed a scarce growth preferably in the pseudomycelium form. C. tropicalis grew very well on the boiled sausage of salami type but mostly in the pseudomycelium form. C. parapsilosis on the other hand, showed a strong growth preferably as round blastospores on all 3 meat products and Cryptococcus neoformans a moderate growth as round blastospores in all the 3 meat products (Bologna type sausage, boiled sausage of salami type and smoke ham). The findings are discussed with a view of their implications for Medical Mycology, epidemiology and the practice of food control.

Blood↗

PubMed1993

Seasonal variation in immediate skin test reactions.

Seasonal variation in the size of immediate prick skin tests was examined in relation to changes in seasonal pollen exposure. Immediate skin test reactions to serial 5-fold dilutions of: (1) a specific pollen during its season (short ragweed), (2) a specific pollen from an earlier season (tree), (3) a perennial allergen (D farinae, D pteronyssinus, or cat), and (4) histamine were examined at the projected trough of ragweed-specific IgE (2nd week in July), at the peak ragweed pollen count (3rd week August), at the estimated peak in ragweed-specific IgE (4th week in September) and at a time of no pollen exposure (2nd week in February). All 30 subjects had symptoms of rhinitis during the ragweed season and a 3 mm or greater wheal to: 100,000 AU/mL of short ragweed, 1:20 wt/vol of a tree exact, and a perennial allergen either 100,000 AU/mL of cat or 10,000 AU/mL of D farinae or D pteronyssinus. The median equivalent dose (dose of skin test material required to produce the median skin test index score) for the four time periods revealed significant seasonal differences. The reactions in October and February were significantly greater than those in July and August for all skin test agents. Histamine, ragweed, and trees showed maximal sensitivity in October, while perennial allergens demonstrated a peak in skin test sensitivity during mid-February.

Adult↗

PubMed1977

[Resistance and biological tolerance of six "inert" parietal protheses. Experimental and critical study (author's transl)].

Six different materials (3 mesh and 3 cloth) commonly used for the repair of abdominal wall hernias were evaluated in rats. 490 animals, distributed among four experimental groups, were implanted with one of the different prostheses through musculature and peritoneum. Serial macroscopic and bacteriological investigations were done. Using an original device, bursting strength of the wound was determined in all groups at intervals. Histological criteria were used to characterize the resistance of the wound and the tolerance of the host to foreign material. Statistical analysis of the results demonstrated that: 1) after the 15th post-operative day, the resistance of the wound was similar for each material tested; 2) during this early period mesh materials exhibited more resistance to bursting pressures than cloth materials; 3) the incorporation of mesh material was constant whereas encystment or extrusion was always observed after implantation of cloth material; 4) no infection occurred with mesh material but significant bacteria were found in 18 p. 100 of cloth material implantations; 5) the extent of the cellular reaction, the enumeration of giant, inflammatory cells and fibroblasts showed superiority of mesh material; 6) the ratio of fibroblasts/inflammatory cells reflected closely the mechanical resistance and tolerance of the foreign material.

Animals↗

PubMed1977

Effects of polyvinyl chloride ingestion by dogs.

Polyvinyl chloride (PVC) acrylic thermoplastic sheeting was fed to 6 dogs to determine whether ingestion during periods of normal transit of military working dogs would be toxic and thus affect the safety of this material for construction of shipping containers. The test dogs were fed PVC acrylic (0.125 g/kg of body weight; by gelatin capsule) twice each day for 5 days: for 2 dogs, the test material was in a shredded form; for 2 dogs, the material was diced; and for 2 dogs, it was powdered. Two other dogs were used as controls. Dogs were observed for clinical signs, and feed consumption and body weights were recorded. Blood and urine samples were examined. All animals were necropsied approximately 10 days after the feeding was stopped. Clinical or pathologic indication of a toxic effect of PVC was not seen within the time limits of the study.

Animals↗

PubMed2004

Biomechanical analysis of the rigid fixation of zygoma fractures: an experimental study.

In this experimental study, the goal was to test the sufficiency of actual fixation plates in zygomatic complex fractures and the efficiency of a modified plate at the zygomaticofrontal suture in a suitable model, which was designed for biomechanical study. To address this issue, a zygomatic fracture model produced by using a cadaveric cranium was simulated and the fractures were fixed by the actual and modified fixation materials. The force simulating masseter muscle pull was applied with the Lloyd material testing apparatus, and the rotation of the zygoma was determined using displacement transducers. In this study, there were three different experimental groups. Although miniplates at the zygomaticomaxillary buttress and microplates at the infraorbital rim were used in all three groups, three different plates (miniplate, microplate, and modified plate) were used at the frontozygomatic suture in these groups. Rotational displacement of the zygoma with the effects of simulated masseter muscle force was determined. According to the results obtained, microplates are not effective in stabilizing the frontozygomatic suture when the masseter muscle forces are within physiological range. Although miniplates stabilize zygomatic complex fractures, it was shown that modified microplates, which have no ondulation along the plate border, have a higher resistance to rotation than that of the conventional plates. The rotation angle at the instant of fracture with microplates was 4.59 degrees, and that with miniplates was 1.26 degrees. The maximum rotation angle with modified microplates was 0.32 degrees. Modified microplates designed for the fixation of fractures in the zygomatico-orbital region have been shown to be suitable in a well-designed experimental model and might be appropriate for clinical use.

Biomechanical Phenomena↗

PubMed1999

Color stability of denture base acrylic resins in three food colorants.

STATEMENT OF PROBLEM: Three commonly used artificial dyes in food technology are erythrosine, tartrazine, and sunset yellow. PURPOSE: The color stability of 5 commercially available denture base acrylic resins (QC-20, Meliodent, Trevalon, Trevalon High, and Lucitone) was studied in vitro. METHODS: The specimens were exposed to 3% erythrosine, tartrazine, and sunset yellow solutions at 23 degrees C +/- 1 degrees C. Color changes were determined with a computer-controlled spectrophotometer. Five specimens from each material were processed, and initial color measurements were made after 1, 3, and 6 months of exposure to the staining solutions. Finally, the color stability was quantitatively measured again, and color differences (DeltaE) were calculated. RESULTS: For the observations made in 1, 3, and 6 months intervals, the specimens that exhibited the least color change were in the sunset yellow solution. The greatest color changes observed according to the National Bureau of Standards unit system were Lucitone (2.71) in erythrosine solution, Lucitone (2.54), QC-20 (1.71) in tartrazine solution, and QC-20 (1.66) in sunset yellow solution. The changes in the other acrylic resins in the 3 solutions were slight and at trace level. CONCLUSIONS: All materials tested were acceptable from the standpoint of color stability for long-term exposure to these food colorants.

Acrylic Resins↗

PubMed2006

[Dychotomic tests in Polish for speech audiometry part 1: preparing material for the tests].

INTRODUCTION: Dychotomic tests in speech audiometry are extremely beneficial, especially in diagnosing central auditory processing disorders. MATERIALS AND METHODS: Basing on new articulatory lists (NLA-93), the authors have prepared a new set of language tests, including filtered speech test, numeral and verbal dichotic tests and Calearo test. CONCLUSIONS: The phonetic characteristics of the tests are presented, with special attention paid to their phonetic balance.

Audiometry↗

PubMed1998

Patch testing with nickel sulfate: comparison between 2 nickel sulfate preparations and 2 different test sites on the back.

Among patients routinely undergoing patch testing for suspected allergic contact dermatitis (ACD), nickel is the most frequently sensitizing hapten, with a clear predominance in the female population. However, some patients who report the appearance of dermatitis upon exposure to metal objects show negative patch test results to a nickel sulfate 5% pet. application. In some cases, a positive response to nickel can be observed simply by repeating the patch test. The objective of our study was to assess if, during routine patch testing, positive responses to nickel sulfate are missed owing to contingent problems, referring to application site, patch test execution or variations in skin reactivity. To this end, we applied 2 different patch test materials containing nickel sulfate 5% pet. to 3040 consecutive patients, undergoing patch testing for suspected allergic contact dermatitis, during the same session. The rôle of the test site was also investigated by applying the preparation on 2 different sites of the back in 30 patients. Of the whole, 612 patients (20%) showed positive patch test responses. The 2 nickel materials were almost equivalent: 78% of nickel-sensitive patients had positive reactions to both, whereas 11% showed a positive response to 1 preparation alone. No variations in patch test responses in relation to application site were observed. Our data show that false-negative patch test responses to nickel are frequent. The use of 2 different preparations during the same patch test session increases the response rate by 10%.

Adolescent↗

PubMed2006

The effects of thermocycling on the flexural strength and flexural modulus of modern resin-based filling materials.

OBJECTIVE: Evaluation of flexural strengths and flexural moduli of hybrids, packables, ormocers, compomers and flowables prior to, and after, thermocycling. MATERIALS AND METHODS: Twenty specimens, size (25 +/- 2) mm x (2 +/- 0.1) mm x (2+/-0.1) mm, of Herculite (HE), Point 4 (P4), TetricCeram (TC), Miris (MI), TetricCeram HB, (HB), Solitaire 2 (SO), Surefil A (SU), Definte (DE), Admira (AD), Dyract AP (DY), Compoglass (CO) and TetricFlow (TF) were made according to ISO 4049. A three-point-bending test was carried out for the first 10 specimens after 24 h water storage at 37 degrees C and for the second 10 specimens after 30-day water storage at 37 degrees C, followed by 5000 thermocycles between +5 and +55 degrees C. For each test series flexural strengths and flexural moduli were calculated. Statistical significance was p < 0.05. RESULTS: Flexural strengths of DY and CO missed the 80 MPa limit of ISO 4049 for occlusal fillings prior to and after thermocycling. AD missed it after thermocycling. HE, P4, TC, MI, HB, SO, SU, DE and TF did not significantly differ prior to and after thermocycling. Flexural strength of SO and AD significantly decreased after thermocycling. No change of the flexural moduli could be observed for any of the test materials. Only SU exceeded 10,000 MPa prior to and after thermocycling. SIGNIFICANCE: Only DY and CO missed the flexural strength limit of ISO 4049 for occlusal fillings. Only SU exceeded a flexural modulus of 10,000 MPa prior to and after thermocycling.

Analysis of Variance↗

PubMed1989

Segmental spinal instrumentation. A study of the mechanical properties of materials used for sublaminar fixation.

Segmental spinal instrumentation with sublaminar fixation is widely used but a variety of materials and techniques are being employed for both scoliosis and other spinal surgery. This study addresses the question as to which is best. Both the materials and the methods of securing them were studied. The materials tested were stainless steel 316L, Ortron 90 high nitrogen steel, titanium alloys, nylon straps, and Mersilene tapes. Doubled cold-worked 00.84-mm diameter stainless steel formed in a knot with a twist proved to be the strongest and most secure means of fixation with a yield value of 1,610 N. Attention to the details of technique and material such as the incorporation of a secondary twist and avoidance of hot-worked stainless steel may reduce the incidence of implant failure.

Bone Wires↗