The influence of implant number and attachment type on maximum bite force of mandibular overdentures: a retrospective study

doi: 10.1111/j.1741‐2358.2010.00421.x
The influence of implant number and attachment type on maximum bite force of mandibular overdentures: a retrospective study Aim: Assessment of the influence of such factors as attachment type, number of implants, gender and age of patients on maximum bite force (MBF). Material and methods: Sixty‐two edentulous patients (32 females, 30 males; aged 64.03 ± 10.07 years, range 42–90 years) with mandibular implant overdentures with various attachment types were included in the study and their MBFs were recorded. The results were evaluated statistically at a significance level of p < 0.05. Results: The MBF in male patients was found to be statistically significantly (p < 0.05) higher than in female patients. No statistically significant differences (p > 0.05) were found with respect to age groups, attachment types and number of implants supporting the mandibular overdentures. Conclusion: Within the limitations of this study, it is concluded that independent of the number applied, dental implants increase MBF in edentulous patients. While males show higher bite force, patient age and attachment type seem not to play an important role.     

Effects of dietary vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of glucocorticoid

The effects of dietary intake of vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of prednisolone were investigated. Rats were divided into five groups. Groups 3, 4, and 5 received a daily supplement in their drinking water of vitamin E, Se, and a combination of vitamin E and Se, respectively, for 30 days. For 3 days subsequently, the control group (group 1) was given a placebo, and the remaining four groups were injected intramuscularly with prednisolone. The tissue samples were collected from each group at 4, 8, 12, 24, and 48 h after the last administration of prednisolone. In the group treated with prednisolone alone, arginase activity in the liver was found to have increased at all the time periods, whereas it had decreased significantly in the heart at 48 h. Arginase activity in the kidneys was not affected by prednisolone. Compared to the control and prednisolone groups, arginase activity in the kidneys and heart of the vitamin E- and Se-supplemented groups was found to be significantly increased at all time periods, however, no difference was seen in the combination group. Arginase activity in the liver of the vitamin E-supplemented group was found to have decreased at all time periods, however, in the Se group compared to the prednisolone group it had reduced at 24 and 48 h only. In the combination group compared to the prednisolone group, liver arginase activity increased constantly up to 12 h returning to normal values at 48 h. Vitamin E and Se in combination may prevent the changes in arginase activity in various tissues caused by prednisolone.     

Histological and biochemical effects of cigarette smoke on lungs

In this study, rats were made to inhale cigarette smoke in a specifically prepared container for different periods. The lung tissue samples of the subjects were examined by light microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Malonaldehyde, one of the free oxygen radicals was determined in lungs and plasma. The catalase activity level of erythrocyte and arginase levels were determined. Three groups were formed. The rats in the Ist and IInd groups were made to inhale cigarette smoke for 30 and 60 minutes a day for a total period of 3 months. Control group, the rats in the IIIrd group (controls) were made to inhale clean air during the same periods. An increase in the number of macrophages was observed in the pulmonary tissue of the exposed groups. Especially in the group that inhaled the smoke for long periods, the number of macrophages and the inclusion bodies contained in them increased. These differences could easily be observed in TEM studies. In the light microscopy and SEM observations, it arouse attention that the alveolar macrophages occurred as sets and their activation increased. Depending on the length of the exposure to cigarette smoke, an increase in the number of macrophages was observed. Statistically significant increases were determined in the malonaldehyde levels of pulmonary tissue and plasma when compared to the control group. Besides significant increases were found in the catalase activity levels of erythrocytes in the experimental groups.     

Comparison of ITO and ZnO ternary glassy composites in terms of radiation shielding properties by Monte Carlo N-particle transport code and BXCOM

In the present study, radiation shielding properties of two glassy composite materials that are widely used in electronics, photovoltaic applications, and sensor technology, were investigated in the photon energy range from 15 keV to 15 MeV. The materials chosen were (ITO)/V2O5/B2O3 and ZnO/V2O5/B2O3 including various concentrations of B2O3. Radiation interaction was simulated and shielding parameters calculated by means of the MCNP and BXCOM codes. More specifically, buildup factors, effective electron density ($$N_{text{eff}}$$) and effective atomic number ($$Z_{text{eff}}$$) were calculated with BXCOM, while mass attenuation coefficients ($$mu /rho$$), half-value layer (HVL) and tenth-value layer (TVL) values were calculated with MCNP. The results were compared with those obtained with the WinXCOM code, for validation. Acceptable and preferable results were obtained for both composites as alternative to other glassy shielding materials. The composite including ITO showed better shielding properties than the composite including ZnO. In terms of radiation shielding, both composites turned out to be better than concrete and close to lead.     

The genetics of a putative social trait in natural populations of yeast

The sharing of secreted invertase by yeast cells is a well‐established laboratory model for cooperation, but the only evidence that such cooperation occurs in nature is that the SUC loci, which encode invertase, vary in number and functionality. Genotypes that do not produce invertase can act as ‘cheats’ in laboratory experiments, growing on the glucose that is released when invertase producers, or ‘cooperators’, digest sucrose. However, genetic variation for invertase production might instead be explained by adaptation of different populations to different local availabilities of sucrose, the substrate for invertase. Here we find that 110 wild yeast strains isolated from natural habitats, and all contained a single SUC locus and produced invertase; none were ‘cheats’. The only genetic variants we found were three strains isolated instead from sucrose‐rich nectar, which produced higher levels of invertase from three additional SUC loci at their subtelomeres. We argue that the pattern of SUC gene variation is better explained by local adaptation than by social conflict.     

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression

The process by which cerebral perfusion is maintained constant over a wide range of systemic pressures is known as “cerebral autoregulation.” Effective dampening of flow against pressure changes occurs over periods as short as ~15 sec and becomes progressively greater over longer time periods. Thus, slower changes in blood pressure are effectively blunted and faster changes or fluctuations pass through to cerebral blood flow relatively unaffected. The primary difficulty in characterizing the frequency dependence of cerebral autoregulation is the lack of prominent spontaneous fluctuations in arterial pressure around the frequencies of interest (less than ~0.07 Hz or ~15 sec). Oscillatory lower body negative pressure (OLBNP) can be employed to generate oscillations in central venous return that result in arterial pressure fluctuations at the frequency of OLBNP. Moreover, Projection Pursuit Regression (PPR) provides a nonparametric method to characterize nonlinear relations inherent in the system without a priori assumptions and reveals the characteristic non-linearity of cerebral autoregulation. OLBNP generates larger fluctuations in arterial pressure as the frequency of negative pressure oscillations become slower; however, fluctuations in cerebral blood flow become progressively lesser. Hence, the PPR shows an increasingly more prominent autoregulatory region at OLBNP frequencies of 0.05 Hz and below (20 sec cycles). The goal of this approach it to allow laboratory-based determination of the characteristic nonlinear relationship between pressure and cerebral flow and could provide unique insight to integrated cerebrovascular control as well as to physiological alterations underlying impaired cerebral autoregulation (e.g., after traumatic brain injury, stroke, etc.).     

A serological survey of selected pathogens in wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis>) in northern Turkey

During the hunting season in March 2012, a total of 93 blood samples were collected from wild boars (Sus scrofa) shot in the area of northern Turkey (Samsun and Gumushane provinces). These blood samples were examined by enzyme immunoassay (ELISA) for the presence of antibodies to classical swine fever virus (CSFV), Aujeszky’s disease virus (ADV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine respiratory coronavirus (PRCV), swine influenza virus (SIV), porcine parvovirus (PPV), swine vesicular disease virus (SVDV), hepatitis E virus (HEV), African swine fever virus (ASFV), porcine rotavirus (PRV), transmissible gastroenteritis virus (TGEV) and bovine viral diarrhoea virus (BVDV). Out of 93 serum samples examined, 65 (69.9 %) were positive for PRV, 22 (23.7 %) were positive for ADV, 5 (5.4 %) were positive for BVDV, 4 (4.3 %) were positive for PPV and 2 (2.2 %) were positive for PRRSV. All sera were negative for ASFV, SVDV, HEV, SIV, PRCV, TGEV and CSFV. The results, recorded for the first time in Turkey, supported the hypothesis that wild boar act as a potential reservoir of selected viruses and thus have a role in the epidemiology of these diseases.     

Development and validation of a FACS-based lipoprotein localization screen in the Lyme disease spirochete <Emphasis Type=Italic>Borrelia burgdorferi</Emphasis>

Background  

In our previous studies on lipoprotein secretion in the Lyme disease spirochete Borrelia burgdorferi, we used monomeric red fluorescent protein 1 (mRFP1) fused to specifically mutated outer surface protein A (OspA) N-terminal lipopeptides to gather first insights into lipoprotein sorting determinants. OspA:mRFP1 fusions could be detected by epifluorescence microscopy both in the periplasm and on the bacterial surface. To build on these findings and to complement the prior targeted mutagenesis approach, we set out to develop a screen to probe a random mutagenesis expression library for mutants expressing differentially localized lipoproteins.     

Ultrastructural Changes in the Kidney of Rats with Acute Exposure to Cadmium and Effects of Exogenous Metallothionein

Ultrastructural changes in the kidneys of rats after acute cadmium exposure and the effects of exogenous metallothionein (MT) were studied by transmission electron microscopy. Thirty-six adult Wistar rats were divided into three groups. Cadmium chloride (CdCl₂) (3.5 mg/kg/day) was injected subcutaneously in the first group. In the second group, 30 μmol/kg MT was administered in addition to CdCl₂. Control rats received 0.5 ml subcutaneous saline solution. Four rats from each group were killed on days 1, 3, 5, and 7 after administration of the compounds. Kidney tissues were taken and fixed in 2.5% glutaraldehyde solution for electron microscopic observations. Tissue damage in kidney increased as time passed since the administration of CdCl₂ in the first group. Degeneration in the proximal and distal tubules was observed. Increased apoptosis was seen in the proximal tubules epithelium, especially on day 7. Peritubular capillaries became dilated, there was degeneration of the endothelial cells, and the amount of intertubular collagen fibers was increased. On day 1, irregular microvilli in the proximal tubules, deepening of the basal striations, and myelin figures; on day 3, multiple vesicular mitochondria and regions of edema around tubules; on days 5 and 7, increased apoptotic cell in the proximal tubules and widened rough endoplasmic reticulum of the endothelial cells of glomerular capillaries were observed. We observed that the structural alterations that increased depending on the day of Cd administration decreased after exogenous MT administration, the dilation of the peritubular capillaries persisted, and there were degenerated proximal tubules. It was established that cadmium chloride was toxic for kidney cortex and caused structural damage. Exogenous MT partly prevents CdCl₂-induced damage.