PubMed Health⌕ Search

Biomedical subjects

M Molin

Publications and source records attributed to M Molin.

At least 19 recordsLinked to original sources
PubMed2006

Surface roughness of five different dental ceramic core materials after grinding and polishing.

In clinical practice, core materials can be exposed after adjustments are made to previously-luted all-ceramic restorations. The purpose of this study was to evaluate the surface roughness of five different dental ceramic core materials after grinding and polishing. Five different ceramic core materials, Vita In-Ceram Alumina, Vita In-Ceram Zirconia, IPS Empress 2, Procera AllCeram, and Denzir were evaluated. Vita Mark II was used as a reference material. The surface roughness, Ra value (mum), was registered using a profilometer. The measurements were made before and after grinding with diamond rotary cutting instruments and after polishing with the Sof-Lex system. The surface of representative specimens was evaluated qualitatively using scanning electron microscopy (SEM). Results were statistically analysed using analysis of variance (anova) supplemented with Scheffè's and Bonferroni multiple-comparison tests. Before grinding, Procera AllCeram and Denzir had the smoothest surfaces, while IPS Empress 2 had the coarsest. After grinding, all materials except IPS Empress 2 became coarser. Polishing with Sof-Lex provided no significant (P > 0.05) differences between Denzir, Vita Mark II and IPS Empress 2 or between Procera AllCeram and In-Ceram Zirconia. There were no significant differences (P > 0.05) either between the ground and the polished Procera AllCeram or In-Ceram Alumina specimens. Polishing of Denzir, IPS Empress 2 and In-Ceram Zirconia made the surfaces smoother compared with the state after grinding, whereas the polishing effect on Procera AllCeram and In-Ceram Alumina was ineffective. The findings of the SEM evaluation were consistent with the profilometer readings.

Aluminum Oxide↗
PubMed2001

Adenovirus vector designed for expression of toxic proteins.

To construct recombinant adenoviruses expressing biologically active proteins may be impossible, or result in a significant reduction in virus yield, if the protein expressed has an inhibitory effect on virus replication or cellular growth. To overcome this problem, we previously designed adenovirus vectors expressing foreign proteins from inducible promoters. However, during our work with a replication-deficient virus expressing the ASF/SF2 splicing factor from a progesterone antagonist-inducible gene cassette, we discovered that ASF/SF2 was expressed at a significant level in the 293 producer cell line, even in the absence of inducer. 293 cells code for adenovirus E1A and E1B proteins and thus support the growth of E1-deficient adenoviruses. Here we show that this background ASF/SF2 expression results from a low level of E1A-mediated transactivation of the basal promoter driving transgene expression. To overcome the problem of leaky expression, we reconstructed a novel gene cassette that combines an inducible promoter and a Lac repressor protein-based block to reduce transcriptional elongation. We show that this novel vector system dramatically reduced background transgene expression and therefore should be useful for the rescue and propagation of high-titer stocks of recombinant adenoviruses expressing toxic proteins.

Adenoviridae↗
PubMed2001

Cisplatin induces the proapoptotic conformation of Bak in a deltaMEKK1-dependent manner.

In a panel of four human melanoma cell lines, equitoxic doses of cisplatin induced the proapoptotic conformation of the Bcl-2 family protein Bak prior to the execution phase of apoptosis. Because cisplatin-induced modulation of the related Bax protein was seen in only one cell line, a degree of specificity in the signal to Bak is indicated. Little is known about upstream regulation of Bak activity. In this study, we examined whether the apoptosis-specific pathway mediated by a kinase fragment of MEKK1 (DeltaMEKK1) is involved in the observed Bak modulation. We report that expression of a kinase-inactive fragment of MEKK1 (dominant negative MEKK [dnMEKK]) efficiently blocked cisplatin-induced modulation of Bak and cytochrome c release and consequently also reduced DEVDase activation and nuclear fragmentation. Accordingly, expression of a kinase-active MEKK1 fragment (dominant positive MEKK) was sufficient to induce modulation of Bak in three cell lines and to induce apoptosis in two of these. dnMEKK did not block cisplatin-induced c-Jun N-terminal kinase (JNK) activation, in agreement with a specifically proapoptotic role for the DeltaMEKK1 pathway. Finally, we show that reduction of Bak expression by antisense Bak reduced cisplatin-induced loss of mitochondrial integrity and caspase cleavage activity in breast cancer cell lines. In summary, we have identified Bak as a cisplatin-regulated component downstream in a proapoptotic, JNK-independent DeltaMEKK1 pathway.

Antineoplastic Agents↗
PubMed2000

Intestinal fatty acid binding protein polymorphism at codon 54 is not associated with postprandial responses to fat and glucose tolerance tests in healthy young Europeans. Results from EARS II participants.

UNLABELLED: Polymorphism Ala54Thr of the intestinal fatty acid-binding protein 2 (FABP2) has been reported to have an effect on the protein's affinity for long chain fatty acids and to be associated with serum lipid and insulin levels in fasting and especially postprandial states. We wanted to test whether this genetic variation is associated with fasting and postprandial glucose, insulin or lipid levels in 666 male university students participating in the second European Atherosclerosis Study (EARS II). We also studied whether the subgroup of 330 students with paternal history of myocardial infarction (MI) before the age of 55 have different genotype distribution than 336 matched controls. RESULTS: No difference in genotype distribution was observed between offspring with and without paternal history of MI or between populations from 11 European countries. The frequency of the threonine encoding allele was 0.276 in cases and 0.266 in controls. There were no differences in fasting or postprandial serum lipid, glucose or insulin levels between subjects having different genotypes. CONCLUSIONS: In this study FABP2 Ala54Thr polymorphism was not associated with lipid or glucose metabolism. In addition to environmental and genetic factors, selection of study population also may explain the difference between this and earlier studies.

Adolescent↗
PubMed2000

Increased apoptosis and increased clonogenic survival of 12V-H-ras transformed rat fibroblasts in response to cisplatin.

Mutationally activated Ras is involved in tumor progression and likely also in drug resistance. Using survival, viability and apoptosis assays, we have here compared the cisplatin sensitivities of FR3T3 rat fibroblasts and a 12V-H-ras transformed subline (Ras2:3). Around 24 h after cisplatin treatment Ras2:3 cells showed higher apoptosis levels and lower viability than FR3T3. This increased sensitivity correlated with weaker cisplatin-induced activation of Jun N-terminal kinase (JNK). In contrast to apoptosis assays, colony formation assays showed that Ras2:3 were more resistant to cisplatin than were FR3T3. This was partly due to the increased cisplatin sensitivity of FR3T3 seeded at low densities, as required in colony formation assays. In addition, Ras2:3 cisplatin survivors had a higher relative proliferative capacity. Cell cycle analyses showed that FR3T3 cells initially responded with a dose-dependent G2 arrest, while Ras2:3 accumulated in S-phase. Experiments with an anti-apoptotic mutant of MEKK1 suggested that the apoptotic response of Ras2:3 cells is not specific to the S-phase fraction. In summary, the cisplatin response of ras-transformed fibroblasts is distinct from that of parental cells, in that they show increased apoptosis, a different cell cycle response and increased post-treatment proliferative capacity. The results illustrate the need to carefully consider methods and protocols for in vitro studies on chemotherapy sensitivity.

Animals↗
PubMed2000

Overexpression of essential splicing factor ASF/SF2 blocks the temporal shift in adenovirus pre-mRNA splicing and reduces virus progeny formation.

Expression of cytoplasmic mRNA from most adenovirus transcription units is subjected to a temporal regulation at the level of alternative pre-mRNA splicing. The general tendency is that splice site selection changes from proximal to distal late after infection. Interestingly, ASF/SF2, which is a prototypical member of the SR family of splicing factors, has the opposite effect on splice site selection, inducing an increase in proximal splice site usage. We have previously shown that SR proteins late during an adenovirus infection become partially inactivated as splicing regulatory proteins. A prediction from these results is that overexpression of an SR protein, such as ASF/SF2, during virus growth will interfere with virus replication by disturbing the balance of functional and nonfunctional ASF/SF2 in the infected cell. To test this hypothesis, we reconstructed a recombinant adenovirus expressing ASF/SF2 under the transcriptional control of a regulated promoter. The results show that, as predicted, induction of ASF/SF2 during lytic virus growth prevents the early to late shift in mRNA expression from both early (E1A and E1B) and late (L1) transcription units. Furthermore, ASF/SF2 overexpression blocks viral DNA replication and reduces selectively cytoplasmic accumulation of major late mRNA, resulting in a lower virus yield. Collectively, our results provide additional support for the hypothesis that viral control of SR protein function is important for the proper expression of viral proteins during lytic virus growth.

Adenoviridae↗
PubMed1999

Interrelationships between low density lipoprotein receptor defect, serum fatty acid composition, and serum cholesterol concentration.

It is known that, in the general human population, serum fatty acid composition is correlated with serum triacylglycerol and cholesterol concentrations. The goal of the present study was to analyze whether the same is true of individuals who have a low density lipoprotein receptor (LDL-R) defect. Concentrations of 16 different fatty acids, cholesterol, triacylglycerol, and major lipoproteins in serum were determined in eight individuals who had (FH-North Karelia), the most common LDL-R defect in Finland, which causes familial hypercholesterolemia, and in their 30 relatives belonging to a single large pedigree as controls. The average number of double bonds (i.e., degree of desaturation) in serum fatty acids correlated negatively with the concentrations of serum total cholesterol (r = 0.27, P < 0.05) and total triacylglycerol (r = -0.71, P < 0.001) and positively with the number of fish meals per week (r = 0.50, P < 0.01), which was analyzed in all pedigree members jointly. These effects were similar in individuals having LDL-R defect, in which group the correlation coefficients were -0.31 (P = NS), -0.99 (P < 0.001), and 0.79 (P = NS) for serum total cholesterol, triacylglycerol, and weekly fish meals, respectively. Thus, LDL-R defect does not impair the correlation between serum fatty acid composition and serum triacylglycerol concentration. This result is in agreement with dietary studies that have shown that familial hypercholesterolemia patients respond very favorably to dietary therapy.

Journal Article↗
PubMed1998

A meta-analysis of implants in partial edentulism.

A meta-analytic technique was used to estimate the survival of implants supporting bridges or single crowns in partially edentulous patients. A survey of the literature revealed 66 studies, published between 1986 and 1996. Nine studies on single implants and 10 studies on fixed partial dentures met the inclusion criteria for the meta-analysis. Data from a total of 2686 implants, 570 single crowns (SC) and 2116 in fixed partial dentures (FPD), were analyzed. In order to calculate annual survival rates for individual studies a life-table analysis was conducted. Maximum follow-up time ranged between 1 and 8 years. After 1 year the success rate was calculated to be at least 85.7% for FPD and 97.2% for SC. When the results from the FPD studies were pooled the survival rate was 93.6% after 6-7 years. The corresponding value for SC was 97.5%.

Chi-Square Distribution↗
PubMed1998

A 5-year clinical evaluation of ceramic inlays (Cerec) cemented with a dual-cured or chemically cured resin composite luting agent.

Sixty-six class-II CAD/CAM-manufactured ceramic inlays (Cerec) were placed in 27 patients. Each patient received at least one inlay luted with a dual-cured resin composite and one inlay luted with a chemically cured resin composite. The inlays were examined 5 years after luting using the California Dental Association (CDA) criteria. Eighty-nine percent of the 66 inlays were rated 'satisfactory'. During the follow-up period replacement was required for 3 inlays because of inlay fractures (4.5%) and 1 inlay because of fracture of the tooth substance (1.5%). All those inlays were luted with the dual-cured resin composite luting agent. Of the remaining 62 inlays the CDA rating 'excellent' was given to 84% for color, 97% for surface, and 81% for anatomic form. 'Excellent' margin integrity was seen in 52% of the dual-cured resin composite luted inlays and in 61% of the chemically cured resin composite luted inlays. No statistically significant (P> 0.05) difference was observed between the two luting agents.

Adolescent↗
PubMed1998

Two novel adenovirus vector systems permitting regulated protein expression in gene transfer experiments.

Two new adenovirus vector systems based on the tetracycline-regulated Tet-ON- (Gossen, M., et al., Science 268:1766-1769, 1995) and the RU 486-regulated progesterone antagonist (Wang, Y., et al., Proc. Natl. Acad. Sci. USA 91:8180-8184, 1994)-induced gene expression systems are described. We show that both systems permit a tight control of chloramphenicol acetyltransferase reporter gene expression in a variety of cell types, with induction levels of approximately 1,800-fold (Tet-ON system) and 600-fold (RU 486-regulated system), respectively. A significant advantage of our vector systems is that reporter protein expression can be adjusted over a wide range by varying the amount of inducer. The Tet-ON system is also shown to permit an efficient control of reporter gene expression in mice.

3T3 Cells↗
PubMed1997

Mercury levels in plasma and urine after removal of all amalgam restorations: the effect of using rubber dams.

OBJECTIVE: The aim of the present study was to determine whether removal of all amalgam restorations might significantly affect mercury levels in plasma and urine and whether the use of rubber dams might reduce patient exposure to mercury during amalgam removal. METHODS: All amalgam restorations were removed from 18 subjects during a single treatment session in which a rubber dam was used and from 10 subjects when a rubber dam was not used. All amalgam restorations were removed by the same dentist using high-speed cutting, water coolant, and high-volume evacuation. The levels of mercury in plasma and urine were analyzed both before and during the subsequent twelve months after amalgam removal. In order to determine whether removal of all amalgam restorations might cause an exposure large enough to significantly increase the mercury levels in two indicator media for mercury exposure, i.e., plasma and urine, and to determine if the removal might cause a significant decrease in the mercury levels found over time, the one-tailed, paired Students' t-test was used. For each individual, the pre-removal levels were compared with both the levels found in plasma on d 1 and in urine on d 10, and also with the levels found 1 y after removal. Furthermore, in order to examine whether the use of rubber dams had any effect on the mercury levels found after removal, the changes in the mercury levels found were compared between the groups using the Wilcoxon-Mann-Whitney rank sum test. RESULTS: After removal of all amalgam restorations, only the non-rubber dam group showed significant increases in the mercury levels found in plasma (p = 0.012) and urine (p = 0.037). However, one year later, the mercury levels in plasma and urine had sunk significantly below the pre-removal levels for both groups. When the changes in the mercury levels found were compared between the groups, the non-rubber dam group showed a significantly higher increase of mercury in plasma than the rubber dam group the day after removal (p = 0.0010). Compared to the pre-removal mercury levels in plasma and urine, the levels found 1 y after removal of all amalgam restorations were on average 52 +/- 23% (range 4-89%) lower in plasma and 76 +/- 21% (range 20-94%) lower in urine. SIGNIFICANCE: The study showed that dental amalgam had a statistically significant impact on the mercury levels found in plasma and urine in the patients tested, and that the use of a rubber dam during removal of all amalgam restorations significantly reduced the peak of mercury in plasma following removal.

Adult↗
PubMed1996

Mercury vapor release from dental amalgam in patients with symptoms allegedly caused by amalgam fillings.

The aim of this study was to determine whether a group of patients with symptoms, self-related to their amalgam restorations, experienced an exposure to mercury vapor from their amalgam restorations that reached the range at which subtle symptoms have been reported in the literature. Furthermore, the aim was to determine whether the mercury exposure for these patients was significantly higher than for controls with no reported health complaints. The symptom group consisted of 10 consecutively selected patients from a larger group, referred by their physicians for investigation into any correlation between subjective symptoms and amalgam restorations. The control group consisted of 8 persons with no reported health complaints. The intra-oral release of mercury vapor was measured between 7:45 a.m. and 9:00 p.m. at intervals of 30-45 min, following a standardized schedule. The mercury levels in plasma, erythrocytes, and urine were also determined. The calculated daily uptake of inhaled mercury vapor, released from the amalgam restorations, was less than 5% of the daily uptake calculated at the lower concentration range given by the WHO (1991), at which subtle symptoms have been found in particularly sensitive individuals. The symptom group had neither a higher estimated daily uptake of inhaled mercury vapor, nor a higher mercury concentration in blood and urine than in the control group. The study provides no scientific support for the belief that the symptoms of the patients examined originated from an enhanced mercury release from their amalgam restorations.

Adult↗
PubMed1996

A 3-year clinical follow-up study of a ceramic (Optec) inlay system.

To evaluate the clinical quality of ceramic (Optec) inlays, the inlay production of 10 dentists, served by 3 dental laboratories, was examined independently by 2 calibrated examiners. Of the 57 patients with 205 inlays participating in the first examination, 47 patients with 145 remaining inlays participated in the 3-year follow-up reexamination. For 14 of the participants in the reexamination, altogether 21 inlays had fractured. The mean time in service before fracture was 26.4 months (range, 12-53 months). The inlays were rated using the California Dental Association (CDA) quality evaluation system. This examination showed that the mismatch of color had increased from the first examination to the reexamination and registered slightly roughened surfaces. As to anatomic form, a reduced number of inlays did not receive an excellent CDA rating at the reexamination. Visible evidence of ditching along the margin had increased by almost 50%, and an apparent discoloration of the margin between the restoration and the tooth structure was seen in 73% of the reexamined inlays, compared with 7% at the first examination.

Adolescent↗
PubMed1995

Effects of gold and bonded ceramic inlays on the ability to perceive occlusal thickness.

Any crown or inlay preparation will be accompanied with pulpal involvement and possible altered biomechanical and/or viscoelastic properties concerning the treated tooth. This study was aimed to assess this influence in terms of differences in interocclusal discrimination threshold value, before and after rehabilitation with gold inlays and by composite resin bonded ceramic inlays. Twenty patients were included and treated with one gold and three ceramic inlays each. For purposes of determining the discrimination threshold between the inlays and antagonizing teeth, plastic foils of different thicknesses were used. Each inlay position, as well as a pair of control teeth, were tested before and after treatment. Before rehabilitation an interocclusal and discrimination threshold of 24 microns at the level of 80% right answers were determined. Treatment with inlays, however, resulted in a significantly different and increased threshold for every tooth/inlays combination. No significant differences between the sessions were recorded for the control teeth. It could be concluded that, in the short term, an oral rehabilitation with inlays and in particular bonded inlays will influence mechanosensitive afferents.

Adult↗
PubMed1995

Ceramic inlays (Cerec) cemented with either a dual-cured or a chemically cured composite resin luting agent. A 2-year clinical study.

On the basis of the criteria of the California Dental Association (CDA), 66 CAD/CAM-manufactured ceramic class-II inlays (Cerec) were compared intraindividually after they had been cemented with either a chemically cured or a dual-cured composite resin luting agent in 27 patients. Plaque and gingival conditions, the overall time consumption for producing each inlay, and the frequency of postoperative sensitivity were also evaluated. There was no statistically significant difference between the two luting agents with regard to the properties evaluated. One inlay was replaced owing to fracture of the restored tooth just before the 24-month re-examination. After 2 years excellent CDA ratings were obtained for color in 92% of the remaining 65 inlays. The corresponding figures for surface and for anatomic form were 100% and 85%, respectively. For margin integrity 85% of the 33 inlays cemented with the dual-cured luting agent and 88% of the 33 inlays cemented with the chemically cured luting agent were rated excellent after 2 years.

Adolescent↗
PubMed1994

Flexural strength of two electro-plated dental ceramics.

This study aimed to investigate the influence on flexural strength of electro-plating two dental porcelains, Vita Omega and Vita Omega 800. The porcelains were treated in accordance with the manufacturer's instructions, and the specimens were produced following the ISO 6872 standard for rectangular bars. Specimens were divided into three groups, of which none, one, or three of the surfaces were plated with a thin layer of gold. Flexural strength was tested with a three-point bending test. Ten specimens were tested for each combination of porcelain and plating, for a total of 60 test pieces. For both porcelains, a significantly higher flexural strength was found for the specimens furnished with a gold layer. The number of covered surfaces did not significantly influence the tested strength. This increase in strength is most likely due to decreased crack initiation and fracture propagation after the covering of random defects in the porcelain. A better stress distribution might also be anticipated and partly explain the results.

Aluminum Silicates↗
PubMed1993

A clinical evaluation of conical crown retained dentures.

In an uncontrolled retrospective recall study of 57 patients treated with conical crown retained dentures, 60 restorations (37 in the maxillae and 23 in the mandible jaw) with a mean wearing time of 30.1 months (range 4 to 76) were evaluated. Of the 248 abutments, eight (3.2%) had been lost. Clinically healthy mucosa was seen in 35 jaws. The marginal fit of the copings was judged to be good. No caries or new restorations were observed in 44 patients. Thirteen patients had 19 surfaces with new restorations and 20 surfaces with caries lesions. Of these 39 surfaces, 38 were located subgingivally.

Adult↗