Evaluation of change in implant abutment after teeth surface modifications.

The surface modifications in teeth increase the retentive strength of cemented castings by providing micro as well as macro retentive ridge and groove patterns. Restoring the dental implants with cement-retained prosthesis is well known. Therefore, it is of interest to compare retentive property of implant abutments with and without circumferential grooves. Hence, 20 straight shoulder type titanium abutments were with abutment screws as well as prefabricated plastic copings and corresponding 12 mm-long stainless steel laboratory implant analogs were used. The abutments were divided into two subgroups of 10 abutments each: without grooves and with grooves. After thermocycling and storing the cemented abutments in water at 37°C water for 6 days they were assembled in the Universal testing machine and subjected to a pullout test (retention) at a crosshead speed of 5.0mm/min to record forces in Newton. Data suggest that the addition of grooves increased the retention. The mean retentive forces of standard machined abutments (plain) cemented with Resin modified GIC showed 339.34 N. Retention increased by 667.39N after addition of circumferential grooves. The surface modification of an implant abutment by means of circumferential grooves is an effective method of improving the retention of cast crowns cemented with resin modified GIC especially in short abutments.

Towards reconstructing the dipteran demise of an ancient essential gene: E3 ubiquitin ligase Murine double minute.

Genome studies have uncovered many examples of essential gene loss, raising the question of how ancient genes transition from essentiality to dispensability. We explored this process for the deeply conserved E3 ubiquitin ligase Murine double minute (Mdm), which is lacking in Drosophila despite the conservation of its main regulatory target, the cellular stress response gene p53. Conducting gene expression and knockdown experiments in the red flour beetle Tribolium castaneum, we found evidence that Mdm has remained essential in insects where it is present. Using bioinformatics approaches, we confirm the absence of the Mdm gene family in Drosophila, mapping its loss to the stem lineage of schizophoran Diptera and Pipunculidae (big-headed flies), about 95-85 million years ago. Intriguingly, this gene loss event was preceded by the de novo origin of the gene Companion of reaper (Corp), a novel p53 regulatory factor that is characterized by functional similarities to vertebrate Mdm2 despite lacking E3 ubiquitin ligase protein domains. Speaking against a 1:1 compensatory gene gain/loss scenario, however, we found that hoverflies (Syrphidae) and pointed-wing flies (Lonchopteridae) possess both Mdm and Corp. This implies that the two p53 regulators have been coexisting for ~ 150 million years in select dipteran clades and for at least 50 million years in the lineage to Schizophora and Pipunculidae. Given these extensive time spans of Mdm/Corp coexistence, we speculate that the loss of Mdm in the lineage to Drosophila involved further acquisitions of compensatory gene activities besides the emergence of Corp. Combined with the previously noted reduction of an ancestral P53 contact domain in the Mdm homologs of crustaceans and insects, we conclude that the loss of the ancient Mdm gene family in flies was the outcome of incremental functional regression over long macroevolutionary time scales.

Presence of antispasmodic, antidiarrheal, antisecretory, calcium antagonist and acetylcholinesterase inhibitory steroidal alkaloids in Sarcococca saligna.

The aim of this investigation was to see if the crude extract of Sarcococca saligna (Ss.Cr) contains chemicals with gut function inhibitory activity by using in vitro and in vivo assays. Ss.Cr caused a dose-dependent (0.03 - 3 mg/mL) inhibitory effect on K+-induced contractions in rat stomach fundus, guinea-pig ileum and rabbit jejunum preparations. The calcium channel blocking(CCB) activity was confirmed when Ss.Cr caused a rightward shift in the Ca++ dose-response curves. It also potentiated, at lower do-ses (0.001 - 0.03 mg/mL), the contractile effect of a fixed dose of acetylcholine (ACh), similar to physostigmine, and suppressed the effect of ACh at higher doses (0.3 - 1.0 mg/mL). Both Ss.Cr and physostigmine inhibited acetylcholinesterase (AChE), in the in vitro assay, confirming the AChE inhibitory activity. In the in vivo studies, Ss.Cr exhibited antidiarrheal and antisecretory activities against castor oil-induced diarrhea and intestinal fluid accumulation in mice. Characteristic steroidal compounds of the plant (saracocine, saracodine, saracorine and alkaloid-C), exhibited a similar combination of AChE inhibitory and CCB activities. Thus this study provides a sound mechanistic base for some of the traditional uses of the plant in hyperactive gut states, in addition to providing the first evidence for verapamil to possess additional AChE inhibitory activity. Furthermore, these characteristic compounds with dual activity may be good candidates for further studies on their usefulness in Alzheimer's disease.