bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Parotid Salivary Proteins by Glucocorticoids
Authors: Johnson D.A. , Etzel K.R. , Alvares O.F. , Cortez J.E.
Published: November 2010

Previous studies have indicated that adrenal-intact rats treated for one week with pharmacological doses of the synthetic glucocorticoid, dexamethasone, show a significant reduction in the proportion of proline-rich proteins and an increase in the proportion of amylase in rat parotid saliva (Johnson et al., 1987). In order to understand more fully the role of glucocorticoids in the regulation of salivary proteins, we performed bilateral adrenalectomies on groups of rats. Some of the adrenalectomized rats were treated with replacement-level doses of the synthetic glucocorticoid, dexamethasone. The food intake was monitored daily for both groups, and sham-operated pair-fed controls were included so that the effects of alterations of food intake could be separated from those of the experimental procedures. After eight to 12 days, uniformly stimulated parotid saliva was collected from these animals as well as from sham-operated controls fed ad libitum. The volume of saliva collected in 30 min was recorded, and the saliva samples were analyzed for concentration and composition of protein. Although the volume of saliva was not affected, parotid saliva collected from adrenalectomized rats exhibited a two-fold greater proportion of proline-rich proteins and reductions in other major secretory proteins: DNase, Fraction I, and Fraction V. The parotid gland secretory granules of adrenalectomized rats were more electron-lucent than in the ad libitum- fed controls. Treatment of adrenalectomized rats with dexamethasone largely prevented the changes in salivary protein composition as well as the alterations in secretory granule morphology. The results of these studies, along with those of our previous report, suggest that glucocorticoids are involved in the regulation of the synthesis of parotid gland secretory proteins.
Testing Sealing Properties of Restorative Materials Against Moist Dentin
Authors: Terkla L.G. , Brown A.C. , Hainisch A.P. , Mitchem J.C.
Published: November 2010

The objectives of this investigation were (1) to develop a sensitive laboratory system that simulates the physiological and clinical conditions of a prepared human tooth in order to facilitate the determination of the bonding and sealing efficacies of restorative dental materials and (2) to conduct experiments with two dentin bonding agents, two posterior composite resin restorative materials (hybrid and micro filled), and a glass-ionomer type II filling material. The system functioned well and provided data to indicate that, after margination, the two posterior composite resin restorative materials performed equally and both performed better than the glass-ionomer filling material; none of the materials provided a perfect seal immediately after insertion, although some restorations demonstrated perfect seals from 16 hours to 28 days after placement; the seal of the glass-ionomer material improved after 28 days of storage in buffer solution; each successive step in the respective composite resin procedures improved the seal except in one case for the micro filled resin.
Wear of Composite Resin Restorations in Primary versus Permanent Molar Teeth
Authors: Wendell J.J. , Vann W.F.
Published: November 2010

The purpose of this investigation was to compare the wear rates of posterior composite resin restorations in primary versus permanent teeth. Based on theories of composite wear in primary molars, as well as on empirical observations, we hypothesized that wear would be greater in permanent tooth restorations. In Part I of the study, quantitative wear data from four different clinical trials (three permanent tooth studies and one primary tooth study) were compared. The same posterior composite restorative material was investigated in each of the four studies.

In Part II of the study, quantitative wear data were drawn from a single clinical trial wherein the same experimental posterior composite material was placed in primary and permanent molars in the same children. In Part II, the baseline sample size included posterior composite restorations placed in 92 primary and 95 permanent molars in all children (ages 7-10). Quantitative wear data were obtained by the cast assessment method at baseline, six, 12, and 24 months. The 24-month sample size was based on 48 available primary molar restorations and 89 permanent molar restorations. The loss of primary restorations was due almost exclusively to natural exfoliations.

Findings in Part I revealed no significant difference in the wear of primary versus permanent molar restorations. In Part II, wear findings for primary molar versus permanent teeth, respectively, were as follows (in micrometers): 47 versus 49 at six months; 86 versus 80 at 12 months; and 133 versus 131 at 24 months. With a Wilcoxon two-sample test and an alpha level of 0.05, there were no significant differences at any recall for the wear rate of primary versus permanent restorations. These results differ sharply from findings reported by others.
Effects on Gingivitis of Two Different 0.4% SnF2 Gels
Authors: Boyd R.L. , Leggott P.J. , Robertson P.B.
Published: November 2010

For nine months we monitored the periodontal health of 81 adolescents undergoing orthodontic treatment with fixed appliances, to determine whether daily use of a brush-on 0.4% SnF 2 gel would be better than toothbrushing alone in maintaining periodontal health in these patients, and whether a gel supplying a high percentage of available Sn2+ ion would be more beneficial than a gel supplying a low percentage of available Sn2+ ion. The subjects were matched for age and sex and placed into a control group, which used toothbrushing alone, and two treatment groups, which used toothbrushing supplemented with daily use of a SnF2 gel. One treatment group used a gel with 98% available Sn2+ ion twice daily for the entire nine months. The other treatment group used a gel with less than 2% available Sn2+ once a day for six months, then twice a day for the remaining three months of the study. Clinical assessments (Plaque Index, Gingival Index, Bleeding Tendency, pocket depth, and coronal staining) were made before appliances were placed and at one, three, six, and nine months after appliances were placed. Results indicated that the group using the high-availability Sn 2+ gel twice daily had significantly lower Gingival Index and Bleeding Tendency scores at the one-, three-, six-, and nine-month examinations than did the control group. The group using the low-availability Sn2+ gel showed no significant differences in these assessments from the control group. Neither treatment group showed significant differences from the control group in Plaque Index or pocket depth. In the group using the high-availability Sn2+ gel, one subject developed mild coronal staining, and two developed moderate staining.
Influence of Tempering and Contraction Mismatch on Crack Development in Ceramic Surfaces
Authors: Anusavice K.J. , Dehoff P.H. , Hojjatie B. , Gray A.
Published: November 2010

Tempering of glass produces a state of compressive stress in surface regions which can enhance the resistance to crack initiation and growth. The objective of this study was to determine the influence of tempering on the sizes of surface cracks induced within the tempered surfaces of opaque porcelain-body porcelain discs, with contraction coefficient differences (αO- αB) of +3.2, +0.7, 0.0, -0.9, and -1.5 ppm/°C. We fired the discs to the maturing temperature (982°C) of body porcelain and then subjected them to three cooling procedures: slow cooling in a furnace (SC), fast cooling in air (FC), and tempering (T) by blasting the body porcelain surface with compressed air for 90 s. We used body porcelain discs as the thermally compatible (Δα = 0) control specimens. We measured the diameters of cracks induced by a microhardness indenter at an applied load of 4.9 N at 80 points along diametral lines within the surface of body porcelain.

The mean values of the crack diameters varied from 75.9 μm (Δα = -1.5 ppm/°C) to 103.3 μm (Δα = + 3.2 ppm/C). The results of ANOVA indicate that significant differences in crack dimensions were controlled by cooling rate, contraction mismatch, and their combined effect (p<0.0001). Multiple contrast analysis (Tukey's HSD Test) revealed significantly lower (p < 0. 05) crack sizes for tempered specimens compared with those of fast-cooled and slow-cooled specimens. Compared with fast cooling, tempering reduced the mean crack diameter by 14.3 μm (13. 8%) for Δα = +3.2 ppm/°C, 20.5 μm (20.2%) for Δα = +0.7 ppml°C, 26.6 μm (26.3%) for Δα = 0, 16.9 μm (19.4%) for Δα = -0.9 ppm/°C, and 15.9 μm (17.3%) for Δα = - 1.5 ppm/°C. These results suggest that physical tempering can reduce the sizes of surface cracks (produced in feldspathic ceramics), which are associated with both positive and negative differences in contraction coefficients of the ceramic layers.
Alteration of Enamel Proteins in Hypomaturation Amelogenesis Imperfecta
Authors: Wright J.T. , Butler W.T.
Published: November 2010

Amelogenesis imperfecta (AI) is a diverse group of disorders that affects primarily the enamel of teeth through a number of developmental processes. The purpose of this study was to characterize the enamel proteins in normal enamel and in hypomaturation AI enamel. Impacted teeth, which were at similar stages of development, were obtained for analysis from an individual with Al and from normal healthy controls. Evaluation of the amino acid profile and quantity of organic material collected showed that there was an excess of enamel protein material that had an amelogenin-like amino acid profile in mature hypomaturation AI enamel. The AI enamel protein content was 5%, while the control enamel had 0.1% protein (by weight). These findings indicate that the maturation process had been altered in this type of AI, and that maturation did not progress beyond the initial stages of secondary mineralization. Since this disorder is inherited as an autosomal recessive condition, it seems likely that the primary defect involves an abnormality in the mechanism for protein removal in enamel maturation.
Caries Incidence in Intact Rats Infected with Streptococcus sobrinus via Transmission from Desalivated Cagemates
Authors: Madison K.M. , Bowen W.H. , Pearson S.K. , Falany J.L.
Published: November 2010

The purpose of this study was to determine the influence of caging desalivated S. sobrinus- infected rats on the caries incidence in intact, previously uninfected cagemates. Weanlings were divided as follows: Stage I: Twenty desalivated animals paired with 20 intact animals (Group I); 20 intact animals paired with 20 intact animals (Group II). Animals were infected with S. sobrinus and fed diet 2000 and 10% sucrose water. After five weeks, ten paired animals from each group were killed. Desalivated animals had statistically higher (p<0.05) caries scores than did other animals. Stage II: The remaining Stage I infected animals from Groups I and II were paired with 40 new uninfected animals 15 days of age and fed cariogenic diets. After five weeks, new intact animals paired with Stage I desalivated animals had significantly higher smooth-surface enamel caries scores (38.0; SE 7.84) than new intact animals paired with Stage I intact animals (11.15 ; SE 3.69). Moreover, new intact animals caged for only five weeks with Stage I desalivated animals developed smooth-surface caries (38.0; SE 7.84) to a degree comparable with that in all Stage I intact animals in the experiment for ten weeks (36.6, SE 9.5 ; and 30.05, SE 4.1). The data suggest that desalivation may select a readily transmissible strain of S. sobrinus, which demonstrates enhanced virulence.
Localization of Chromogranins, Non-neuron-specific Enolase, and Different Forms of Somatostatins in the Submandibular Salivary Glands of Mice
Authors: Letić-Gavrilović A. , Abe K.
Published: November 2010

The localizations of chromogranins A, B, and C, neuron-specific enolase (NSE, γγ-type) and non-NSE (αα-type), and different forms of somatostatins were immunocytochemically identified. The localizations were compared with those of epidermal growth factor (EGF) and nerve growth factor (NGF) in the submandibular salivary glands (SMG) of male mice at five to six weeks of age, with use of a variety of antibodies and the peroxidase-antiperoxidase (PAP) and avidin-biotin complex (ABC) detection methods.

In the SMG of male mice, the major chromogranin present was chromogranin A, whereas chromogranins B and C were not detected at these ages by either method. Chromogranin Alike immunoreactivity was located in the granular convoluted tubule (GCT) cells of the SMG, whereas non-NSE immunoreactivity was observed throughout the duct system and in some acinar-associated cells. NSE was not detected in any part of the SMG. The distribution of chromogranin A and somatostatins in the GCT cells was similar to that of EGF and NGF. Our results strongly suggest that chromogranin A and somatostatins, but not chromogranin B or C, may be useful as a means of differentiation of the cells in the duct system of the SMG responsible for the production of biologically-active factors.
A Light and Scanning Electron Microscopic Study of Enamel Decalcification in Children Living in a Water-fluoridated Area
Authors: Thylstrup A. , Boyar R.M. , Holmen L. , Bowden G.H.
Published: November 2010

Eleven children, each having one or two pairs of premolars to be extracted for orthodontic purposes, participated in the study. The model involved placement of a special orthodontic band that allowed the accumulation of plaque in a defined area between the band and the buccal enamel. Examination of enamel changes was carried out in experimental teeth that had been exposed to local plaque accumulation for one, two, four, eight, or 14 days. The specimens were examined under the light (LM) and the scanning electron microscope (SEM). All teeth had signs of very mild dental fluorosis. No indications of demineralization were noted after one day. SEM examination showed signs of crystal dissolution in some of the two-day specimens. Six of eight four-day specimens exhibited surface dissolution. All eight- and 14-day specimens showed signs of surface demineralization in the LM as well as in the SEM. These observations documented that undisturbed bacterial deposits are capable of initiating enamel demineralization within short time periods, even in children living in a water-fluoridated area.
Analysis of Particle Size Distribution of Hydroxyapatite Crystallites in the Presence of Synthetic and Natural Polymers
Authors: Nancollas G.H. , Budz J.A.
Published: November 2010

The particle size distribution (PSD) of suspended hydroxyapatite crystallites both at equilibrium and during crystal growth has been measured by a laser scattering technique. Addition of high-molecular-weight polyacrylate (PAA/C) resulted in appreciable crystallite aggregation, probably by polymer bridging of particles. In contrast, a lower-molecular-weight PAA was unable to bridge the hydrodynamic gap between particles and resulted in an overall dispersion. The addition of human serum albumin also markedly influenced the PSD and, with concomitant change in zeta potential to more negative values, resulted in dispersion due to steric interaction and electrostatic repulsion between the particles. The complex behavior of human saliva is illustrated by its tendency both to aggregate and to disperse hydroxyapatite crystallites, displaying the combined effects of different adsorbing macromolecules.
A New Approach to the Study of Tooth Wear
Authors: Teaford M.F. , Tylenda C.A.
Published: November 2010

Human tooth wear occurs so slowly that traditionally it has needed months or years to be measurable. This study showed that microscopic changes in wear patterns on human teeth could be detected in a matter of days and could be used as indicators of rates of wear. Thus, daily or weekly changes in rates of wear can be documented for specific locations on teeth. For instance, through this new approach, rates of wear of human teeth were shown to be significantly slower than rates of wear of the teeth of laboratory monkeys raised on hard or soft diets. Similar techniques may ultimately be used to monitor subtle changes in tooth use-including those associated with growth and development and those occurring in response to various dental clinical procedures.
A Multi-station Dental Plaque Microcosm (Artificial Mouth) for the Study of Plaque Growth, Metabolism, pH, and Mineralization
Authors: Sissons C.H. , Cutress T.W. , Hoffman M.P. , Wakefield J.St.J.
Published: November 2010

A plaque growth chamber was developed for long-term growth of five separate plaques from the same plaque or saliva sample under identical conditions of temperature and gas phase. Reagent addition and growth conditions for each plaque could be independently controlled, and each was accessible for sequential sampling and electrode insertion. Plaques were cultured for over six weeks on pellicle-coated Lux (TM) 25-mm diameter cover-slips at 35°C under 5% CO2 in N 2, and supplied with a medium containing 0.25% mucin (BMM) at 3.6 mL/h, and with periodic 5% sucrose. Electron microscopy and flora analysis of microcosm plaques showed that they had close similarities to reported characteristics of natural dental plaques. Diverse motile bacteria were present. Sucrose-induced Stephan pH curves and urea-induced pH rises were also similar to those reported for natural plaques. Changes in plaque urease, calcium, phosphate concentrations, and the flora were followed over five weeks in a plaque supplied with BMM containing additional 2.5 mmol/L calcium and 7.5 mmol/L phosphate. Despite this high environmental calcium phosphate concentration, there was no continuing increase in calcium levels, although plaque phosphate doubled. Urease levels fluctuated. Changes in the cultivable flora were minor. A urea-containing calcium phosphate/ mono-fluorophosphate pH 5 solution, applied for six min every two h for seven days, increased plaque calcium, phosphate, and fluoride to high levels. Thus, plaques grown over several weeks in the multi-station artificial mouth exhibited metabolic and pH behavior typical of natural plaques, could be analyzed during development, and the system allowed manipulation of environmental variables important in plaque pH control and calcification.
Effects of Ascorbic Acid Depletion and Supplementation on Periodontal Health and Subgingival Microflora in Humans
Authors: Leggott P.J. , Robertson P.B. , Jacob R.A. , Zambon J.J. , Walsh M. , Armitage G.C.
Published: November 2010

This study describes the relationship between varying ascorbate intake, periodontal status, and subgingival microflora as part of a multidisciplinary investigation of ascorbic acid (AA) metabolism in young men housed for 13 weeks in a nutrition suite that provided controlled periods of ascorbic acid depletion and repletion.

Twelve medically healthy non-smoking men, aged 25 to 43 years, ate a rotating four-day diet adequate in all nutrients except ascorbic acid. Following an initial baseline period during which the subjects received 250 mgAA/day, the subjects received 5 mgAA/day for a 32-day depletion period. Eight of the 12 subjects participated in a subsequent 56-day repletion period designed to replace the reduced body AA pool slowly. Plasma and leukocyte ascorbate levels, Plaque Index, Gingival Index, probing depths, and attachment level were monitored at the beginning and end of the depletion and repletion periods. Subgingival plaque samples were obtained and examined for selected organisms by indirect immunofluorescence microscopy. A uniform oral hygiene program was reinforced after each examination.

Ascorbate concentrations in plasma and leukocytes responded rapidly to changes in vitamin C intake. There were no significant changes in plaque accumulation, probing pocket depth, or attachment level during the study. In contrast, gingival bleeding increased significantly after the period of AA depletion and returned to baseline values after the period of AA repletion. However, no relationship could be demonstrated between either the presence or proportion of target periodontal micro-organisms and measures of gingival bleeding or ascorbate levels.
The Effects of Hypocalcemia/Hypophosphatemia on Porcine Bone and Dental Hard Tissues in an Inherited Form of Type 1 Pseudo-Vitamin D Deficiency Rickets
Authors: Limeback H. , Schlumbohm C. , Sen A. , Nikiforuk G.
Published: November 2010

The effects of Vitamin D deficiency rickets on the formation of mineralized dental tissues were studied in a breed of pigs which had moderate and marked hypocalcemia because of an inherited defect in the renal production of the biologically-active Vitamin D metabolites. Affected piglets developed classical symptoms of rickets which were fatal unless Vitamin D supplements were given. The dissected mandibles of homozygous (rickets) and heterozygous (normal) pigs were photographed and radiographed. Compared with those of normal pigs, the mandibles of homozygous pigs demonstrated slowed development/eruption of permanent teeth, under-mineralized bone, underdeveloped dentin (enlarged pulp chambers), interglobular dentin, and enamel hypoplasia. Enamel defects in rachitic pig teeth were difficult to observe radiographically, but could be detected visually and by SDS-PAGE analysis of the enamel protein components of developing and maturing enamel. There was significant retention of amelogenins in the enamel maturation zones of developing molars taken from rachitic pigs, but there was no obvious difference in the patterns of amelogenin processing.
Restriction Fragment Length Polymorphism Analysis of the Fimbrillin Locus, fimA, of Porphyromonas gingivalis
Authors: Loos B.G. , Dyer D.W.
Published: November 2010

With hybridization probes derived from the fimbrial locus of Porphyromonas gingivalis strain 381, fimA381' restriction fragment length polymorphisms (RFLPs) were examined at the fimbrillin locus in 39 human and animal strains of this species. The 39 strains were subdivided into nine RFLP groups (I-IX) after genomic digests were probed with the internal coding sequence of the fimA381 gene. Thirty-three strains showed one or more AluI fragments of moderate-to-high homology (≥77%) with the internal coding sequence of fimA381. These strains were distributed into the first seven RFLP groups, based solely on the size of the major hybridizing AluI fragment. Five human strains (RFLP Group VIII) had only one Alu I fragment that hybridized very poorly with this probe. One animal strain did not have homology at all (RFLP Group IX). When all AluI fragments that hybridized with fimA381 were analyzed, RFLP groups I-VIII were further differentiated into 25 distinct RFLP patterns. Hybridizations were also performed with the internal coding sequence of fimA381 to probe PstI genomic digests of selected strains that appeared to have lesser homology with fimA381. These hybridizations were performed to determine the level and location of the region of poor homology within the fimA genes of these strains. The results suggested that fimbrial coding sequences are more commonly conserved between these strains in the 5'-region of the fimA locus (≥92% sequence homology). However, the five human strains of RFLP Group VIII had only one PstI fragment that hybridized very poorly with a probe derived from fimA381 coding sequence, and this sequence homology (only > 66%) was located in the central or 3'-end of the fimA gene. The 5'-region of the fimA allele in Group VIII strains did not have any detectable sequence homology. In contrast, the Group VIII strains were highly homologous with the sequences flanking the fimA381 gene. This indicates that these strains do possess a fimA allele at the same chromosomal location as fimA381.
Fluoride Sorption Characteristics of Different Grades of Bone Charcoal, Based on Batch Tests
Authors: Mwaniki D.L.
Published: November 2010

Although bone charcoal (char) has been recommended for use in the de-fluoridation of drinking water in developing countries, parameters relating to fluoride (F) sorption characteristics by grade or type of bone char are unclear. Based on batch tests, the rate and capacity of F uptake were highest with black grade, followed by grey grade and lowest with white grade. Twenty-four- hour contact-time F sorption isotherms indicated saturation at capacities of 11.4 mg F per g of black grade, 2.4 mg F per g of grey grade, and less than 0.3 mg F per g of white grade bone char. Additional investigations showed that F-removal efficiency of black grade char decreased steadily with increasing F concentration. Its initial sorption kinetics were dependent on particle size, and the highest sorption rate was observed with particle sizes below 0.42 mm. For maximum sorption rate, the critical mixing time was between five and 15 min. The presence of chloride anions and elevated temperatures increased the rate of F uptake by black bone-char. The pH of distilled water following contact with bone char rose to 11.5 for white bone-char, 8.3 for grey bone-char, and 7.8 for black bone-char. The effects of processing temperature on the availability of intra- and extraapatitic F-binding sites, levels of oxides of calcium and magnesium, and the carbon content were viewed as possible causes of observed variations. These findings suggest that the black grade of bone char was the most efficacious for use in partial de-fluoridation of drinking water.
The Role of Phospholipase A2 in Interleukin-1α-mediated Inhibition of Mineralization of the Osteoid Formed by Fetal Rat Calvaria Cells in vitro
Authors: Ellies L.G. , Heersche J.N.M. , Pruzanski W. , Vadas P. , Aubin J.E.
Published: November 2010

Interleukin-1 (IL-1) may be an important mediator of bone remodeling, since it is a potent stimulator of bone resorption and has biphasic effects on bone formation. Continuous exposure of fetal rat calvaria (RC) cells to IL-la or IL-1β results in a dose-dependent inhibition of both bone nodule formation and mineralization of the organic matrix. In this study, the effects of recombinant human IL-1α on the mineralization process were examined by the addition of IL-la late in the culture period, after osteoid nodules had formed and when they were induced to mineralize by the addition of organic phosphate. By means of a quantitative 45calcium radiolabeling assay, it was shown that short-duration exposures of fully-formed bone nodules to IL-la also inhibited mineralization, and that the duration of treatment directly correlated with the degree of inhibition. Because our earlier studies had demonstrated that IL-1 stimulated the release of PLA2 and PGE2 from RC cells, the effects of PLA2 and of inhibition of PGE2 synthesis on mineralization were investigated. Exogenous Naja naja group I PLA2 had little effect on the mineralization of bone nodules; however, Crotalus adamanteus group II PLA2 inhibited mineralization at concentrations similar to those found in the media from IL-la-treated cultures. Although PLA2 is thought to stimulate PGE2 synthesis by releasing arachidonic acid from membrane phospholipids, PGE2 release by RC cells accounted for only part of the IL-la-mediated inhibition, suggesting the presence of other mechanisms of exogenous PLA2 action in inhibiting mineralization. These results suggest that the IL-1-induced synthesis and release of PLA 2 from RC cells is primarily responsible for the inhibition ofmineralization seen in vitro with exposure to IL-1. Thus, the presence of IL-la in vivo at sites of chronic inflammation or infection may compromise tissue repair by inhibiting bone formation and mineralization as well as stimulating bone resorption.
Amplitude and Timing of EMG Activity in the Human Masseter Muscle during Selected Motor Tasks
Authors: Van Eijden T.M.G.J. , Blanksma N.G. , Brugman P.
Published: November 2010

Electromyographic (EMG) activity in the human masseter muscle was registered from six different sites, in the anterior, middle, and posterior regions of the superficial and deep layers of the muscle, during static clenching tasks (intercuspal and incisal), selected jaw movements (alternating protrusion/retrusion, right/left latero-deviation, and open/close excursions), and unilateral chewing on right and left sides. Peak-EMG amplitudes and the timing of the peaks were compared. Activity in the regions of the deep masseter was either higher (in mastication and intercuspal open/close excursions) or lower (incisal clenching) than the activities in the superficial masseter. Superficial and deep masseter also differed in their timing of peak EMG: During chewing, peak activity passed from superficial to deep in the balancing-side muscle, and from deep to superficial on the chewing side. During free latero-deviations, peak activity started in the deep masseter, when the jaw moved to the right side (i.e., the side of the muscle), and then passed to the superficial regions, after the jaw movement was reversed to the left side. In addition, within the deep masseter there existed clear anteroposterior differences in activation level (during incisal clenching and open/close excursions) and in timing (during latero-deviation). Such a differentiation of activity was not found in the superficial masseter.
Spatial and Gender-dependent Variations in Perioral Pinprick Sensitivity
Authors: Lee J. , Essick G.K.
Published: November 2010

Twenty-eight right-handed young adults participated in a sensory testing experiment to evaluate pinprick sensitivity at ten spatially matched sites on the right and left sides of the face. Stimuli were provided by a sharp-pointed dental explorer on which a rubber eraser had been positioned to minimize variations in the extent to which the skin was indented. Sharpness was defined as the magnitude at which abrupt, localized pricking/stinging sensations were evoked. A magnitude matching procedure was used to reduce among-subject variability in the data. Specifically, each estimate of sharpness was adjusted (i.e., divided) by the subject's mean estimate of the brightness of a visual stimulus. Prior to data collection, subjects were carefully instructed on the use of a common numerical scale for assignment of values of sharpness and brightness. Repeated-measures analysis of variance of the adjusted estimates of sharpness revealed a non-significant effect of gender (p > 0.4), a highly significant effect of side (p < 0.0001), and a highly significant effect of test site (p < 0.0001). Pinprick percepts were sharper on the left side of the face than on the right. Moreover, the vermilion of the upper lip exhibited the greatest sensitivity to pinprick; the vermilion of the lower lip exhibited the least sensitivity. These results suggest that use of a patient's sensitivity to pinprick during clinical neurosensory examination must be undertaken in an informed manner. A conclusion of pathological alteration in sensation can be made only after consideration of the normal spatial variations in the percept of sharpness.
Dynamic Mechanical Analysis of Electron Beam Irradiated Waste Polyethylene and its Blends with Virgin High Density and Low Density Polyethylene
Authors: Satapathy Sukanya , Nando Golok Bihari , Nag Ahin
Published: November 2010

Dynamic mechanical properties of blends of waste polyethylene and virgin high density as well as low density polyethylene have been investigated before and after exposure to electron beam irradiation. Effect of radiation dose on the loss modulus, storage modulus, and damping factor of the blends has been reported. An increase in relaxation temperatures on exposure to radiation has been observed. Peak broadening has also been observed on exposure to radiation. The storage modulus and loss modulus of the blends increase, while that of tan δ decreases on irradiation.
Mechanical Performance of Nanostructured Thermoplastic Polyimide Films
Authors: Allie Lazbourne , Aglan Heshmat
Published: November 2010

The effects of multiwalled carbon nanotubes (MWCNTs) on the mechanical performance, namely, strength, fracture resistance, and creep recovery of polyimide (PI) films, were investigated by testing different formulations of PI/MWCNTs films. The loadings of MWCNTs used were 0.1 and 0.5 wt%. A novel method of dispersing MWCNTs in PI was developed and optimized. The processing conditions for fabricating PI films have also been developed and optimized. The mechanical performance of the optimized PI films was evaluated. It was found that the strength of the PI films dried at 60°C increased by 55% and 72% for the 0.1% MWCNT and 0.5% MWCNT loadings, respectively, while the fracture resistance increased by 23% for the 0.1% MWCNTs and then decreases at a loading of 0.5% MWCNTs. The strength of the neat and nanostructured films increased after annealing. However, there was a shift in the annealing temperature at which the maximum strength occurs as the MWCNT loadings increased. The fracture resistance of all the samples increased at an annealing temperature of 150°C and then decreased as the temperature continued to increase up to 250°C. Creep recovery studies showed that the compliance of the PI films decreased with increasing MWCNT loading at room temperature and increases for all the samples as the testing temperature increases to 200°C. Also, the viscosity and percentage strain recovery of the samples increased with increasing MWCNT loading and decreased with increasing temperature. Generally, the percentage strain recovery is between 85%, for samples tested at high temperatures (200°C), and 94%, for those tested at low temperatures (25°C).
Strategy Changes as a Response to Alterations in Tax Policy
Authors: McCutchen William W.
Published: November 2010

This study examines how firms in the pharmaceutical industry responded to the R&D tax credit which was enacted in 1981. The change in research intensity (research/sales) subsequent to the tax change was estimated for the firms. An increase in research intensity was associated with the adoption of the tax credit. The strong response by the firms to the tax credit and the effort to maintain their relative position in research intensity indicate that research intensity is an important strategic dimension and driving force in the industry.
Using Planned Comparisons in Management Research: A Case for the Bonferroni Procedure
Authors: Castaiieda Maria B. , Levin Joel R. , Dunham Randall B.
Published: November 2010

This article describes the Bonferroni multiple-comparison procedure, and makes a case for researchers’ more frequent and appropriate use of it. The procedure is discussed as a test that facilitates investigation of precise and powerful a priori multiple comparisons. Characteristics of the Bonferroni procedure are described in relation to the more familiar Scheffe post hoc multiple-comparison method, and a step-by-step guide for comparing and choosing between the two is provided. The Bonferroni procedure is discussed in detail in the context of one-factor analysis-of-variance designs. Application of the technique is then considered in the context of factorial designs, analyses of covariance, univariate repeated-measures analyses, multivariate analyses of variance, and recent sequential hypothesis-testing extensions. To aid the presentation, an example from the field of management is included.
Trends in Research Design and Data Analytic Strategies in Organizational Research
Authors: Stone-Romero Eugene F. , Weaver Amy E. , Glenar Jennifer L.
Published: November 2010

We coded all articles that were published in the Journal of Applied Psychology in the 1975-1993 period (N = 1,929) in terms of the type research design used in studies (e.g., experimental, nonexperimental), and the major strategies used in analyzing the data of the studies (e.g., analysis of variance, multiple correlation/regression, covariance structure analysis) and computed annual frequencies of use of the research designs and the data analysis strategies. These frequencies were used to compute yearly percentage use indices (PUIs) for each of the designs and data analytic strategies. Results showed that over the period considered: (I) there were fairly minor fluctuations in the PUIs for experimental and nonexperimental designs; (2) the PUI for covariance structure analysis procedures (e.g., LISREL, EQS) was very low during the 1975-1984 period but has increased dramatically thereafter; (3) the PUIs for multiple regression and several other multivariate data analytic strategies have increased somewhat over time; and (4) the PUIs for data analytic procedures that involve tests of mean differences have fluctuated over time, but there is a slight decrease in the use of ANOVA. Implications of these trends are considered.
Planned versus unplanned risks: Neurocognitive predictors of subtypes of adolescents’ risk behavior
Authors: Maslowsky Julie , Keating Daniel P. , Monk Christopher S. , Schulenberg John
Published: November 2010

Risk behavior contributes to substantial morbidity and mortality during adolescence. This study examined neurocognitive predictors of proposed subtypes of adolescent risk behavior: planned (premeditated) versus unplanned (spontaneous). Adolescents (N = 69, 49% male, M = 15.1 [1.0] years) completed neurocognitive tasks (Iowa Gambling Task [IGT], and Game of Dice Task [GDT]) and a self-report measure indicating whether past-year risk behaviors were planned or unplanned. As hypothesized, identifying more beneficial choices on the neurocognitive tasks and perceiving benefits of risk behavior to outweigh costs predicted engagement in planned versus unplanned risk behavior. This study is the first to use neurocognitive assessments to differentiate planned and unplanned subtypes of risk behavior. Understanding mechanisms underlying these subtypes may inform prevention programs targeting specific contributors to adolescent risk behavior.
Relations between parenting and child behavior: Exploring the child’s personality and parental self-efficacy as third variables
Authors: Meunier Jean Christophe , Roskam Isabelle , Browne Dillon T.
Published: November 2010

The present study explores the bidirectional associations between parental behavior and child externalizing behavior in the context of two intervening variables: child’s personality as a moderator of the effect of parental behavior on later child behavior; and parental self-efficacy as a mediator of the effect of child behavior on later parental behavior. Data were collected twice within one year from a sample of 340 preschoolers and their parents. Using latent variable SEM, three models were computed separately for mother—child and father—child dyads. A bidirectional effect was verified for the mothers, but only a child effect was observed for the fathers. Expected mediation by self-efficacy was verified. Finally, a partial moderating role for child’s personality was demonstrated.
The equity funding of smaller growing companies and regional stock exchanges
Authors: Amini Shima , Keasey Kevin , Hudson Robert
Published: November 2010

The credit crisis has led to tightened bank so lending to smaller firms it is no surprise that the debate concerning the re-introduction of regional stock exchanges into the UK has received fresh impetus. This article analyses all UK based Initial Public Offerings (IPOs) on the Alternative Investment Market (AIM) to contribute to this debate and the small firm funding literature. The results indicate that London has dominated IPO activity on the AIM; this reflects the dynamism of this local economy rather than differential funding across the regions. A more fruitful approach than developing regional stock exchanges might be for the current stock exchange to develop stronger links with small business advice and networking organizations working with these existing mechanism/structures to enhance the supply of equity and debt finance to suitable firms much earlier in their life-cycles.
The interval scaling properties of the London Handicap Scale: an example from the adaptation of the scale for use in Turkey
Authors: Kutlay Şehim , Küçükdeveci Ayşe A , Yanık Burcu , Elhan Atilla , Öztuna Derya , Tennant Alan
Published: November 2010

Objectives: To adapt the London Handicap Scale into the Turkish language, and to investigate the scaling properties of this version in a sample of people who have experienced a stroke.

Design: After the translation process, the internal construct validity was tested by Rasch analysis and the reliability by internal consistency and intraclass correlation coefficient. The interval scaling properties were assessed by contrasting the raw and weighted London Handicap Scale scores with the Rasch latent estimates.

Setting: An outpatient rehabilitation unit of a university hospital.

Subjects: One hundred and eighty-eight community-dwelling post-stroke patients (mean age 63 (SD 12) years, 54% male) were assessed by the Turkish version of the London Handicap Scale.

Results: After adjustment for local dependency, the data showed good fit to Rasch model expectations with a mean item fit −0.240 (SD 1.868), person fit −0.403 (SD 0.893) and chi-square interaction 8.55 (df 10, P = 0.575). The reliability was good with a Cronbach’s α and intraclass correlation coefficient of 0.845. Analysis of the scaling properties showed that either the raw London Handicap Scale score or its weighted score were non-linear with respect to the Rasch latent estimate.

Conclusions: The London Handicap Scale is a valid and reliable scale for use in stroke in Turkey. Its unweighted raw scores and weighted scores are equivalent and ordinal, but a linear transformation is possible through Rasch analysis.
Influence of combined aerobic and resistance training on metabolic control, cardiovascular fitness and quality of life in adolescents with type 1 diabetes: a randomized controlled trial
Authors: D’hooge Roseline , Hellinckx Tinneke , Van Laethem Christophe , Stegen Sanne , De Schepper Jean , Van Aken Sara , Dewolf Daniel , Calders Patrick
Published: November 2010

Objective: To evaluate the effect of combined exercise training on metabolic control, physical fitness and quality of life in adolescents with type 1 diabetes.

Design: A double-blind randomized controlled trial with patients receiving combined aerobic and strength or no training.

Setting: University Hospital Ghent (Belgium).

Subjects: Sixteen children with type 1 diabetes were randomized into a control group ( n = 8) and an intervention group ( n = 8).

Interventions: Patients participated twice a week for 20 weeks in the combined aerobic and strength group. The control group continued their normal daily activities.

Main measures: Before and after the intervention anthropometric variables (weight, length, BMI, body composition), metabolic control (glycaemia, HbA1c, daily insulin injected), aerobic capacity (peak Vo2, peak power, peak heart rate, 6-minute walk distance), strength (1 repetition maximum of upper and lower limb, hand grip strength, muscle fatigue resistance, sit-to-stand) and quality of life (SF-36) were assessed.

Results: At baseline, none of the measured parameters differed significantly between the two groups. There was no significant evolution in the groups concerning anthropometric indices, glycaemia and HbA1c. However, the daily doses of insulin injected were significantly lowered in the training group (0.96  IU/kg.day pre versus 0.90  IU/kg.day post; P <  0,05), while it was increased in the control group. Physical fitness increased significantly in the training group. General health, vitality and role emotional had a tendency to improve.

Conclusion: Combined exercise training seemed to lower daily insulin requirement and improve physical fitness, together with better well-being.
Migraine and weather: A prospective diary-based analysis
Authors: Zebenholzer Karin , Rudel Ernest , Frantal Sophie , Brannath Werner , Schmidt Karin , Wöber-Bingöl Çiçek , Wöber Christian
Published: November 2010

Aims

Weather is mentioned as a trigger factor by migraine patients most frequently. We examined the impact of meteorological factors and the impact of their day-to-day change on the risk of occurrence and persistence of headache and migraine and the correlation of subjective weather perception with objective weather data.

Methods

We performed a prospective, diary-based cohort study in 238 patients suffering from migraine with or without aura. Patients had to live within 25 km of the Vienna meteorological station and were required to keep a diary for 90 days. We analysed 11 meteorological parameters and 17 synoptic weather situations. For evaluating the hazard of occurrence and persistence of migraine and headache, we performed a univariate and a stepwise multivariate Cox regression analysis. We calculated correlations between subjective weather perception and meteorological data.

Results

In the uni- and multivariate analysis, a ridge of high pressure increased the risk of headache occurrence, lower mean daily wind speed increased the risk of migraine occurrence and a day-to-day change of daily sunshine duration increased the risk of migraine occurrence. A day-to-day change of the daily minimum temperature decreased the risk of migraine persistence. After correction for multiple testing, none of these findings remained statistically significant. Subjective weather perceptions did not correlate with the occurrence or persistence of migraine or headache. Subjective perception of cold and too-cold weather and of too-warm weather correlated with daily minimum, mean and maximum temperature.

Conclusion

The influence of weather factors on migraine and headache is small and questionable.
P53 and Bcl2 apoptosis proteins in meso-2,3-dimercaptosuccinic acid treated lead-intoxicated rabbits
Authors: Tousson Ehab , Rafat Bassem M , Hessien Mohamed , El Barbary Ahmed A , Sami Ahmed
Published: November 2010

Lead (Pb) toxicity is one of the commonest environmental problems in our life; it causes many reversible and irreversible changes in our tissues. This study was carried out to investigate the effect of meso-2,3-dimercaptosuccinic acid (DMSA) on treatment of oxidative stress caused by lead poisoning in rabbits. Lead acetate (Pb(Ac)2) was orally administrated to rabbits for 21 days and then treated by DMSA for another 21 days. The effect of this treatment was investigated by measuring 2 of the apoptosis proteins p53 and Bcl2. Also, the auto-oxidation rate and their histopathological changes in brain, bone and liver were investigated. Hemoglobin auto-oxidation rate is measured as well as histopathological study of liver. Our data indicate that exposure to rabbits to Pb(Ac)2 caused a significant increase of apoptosis protein p53 and decrease in the antiapoptotic BCl2 proteins.
Magnetic resonance imaging and safety aspects
Authors: Coskun Ozlem
Published: November 2010

Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. MRI is safe, but if something goes wrong, it can go very wrong. Most reported cases of MRI-related injuries and the few fatalities that have occurred have apparently been the result of failure to follow safety guidelines or of use of inappropriate or outdated information related to the safety aspects of biomedical implants and devices. To prevent accidents in the MRI environment, therefore, it is necessary to revise information on biologic effects and safety according to changes that have occurred in MRI technology and with regard to current guidelines for biomedical implants and devices. This review provides an overview of and update on MRI biologic effects, discusses new or controversial MRI safety topics and issues, and presents evidence-based guidelines to ensure safety for patients and staff.