Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties.

Objective

This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply).

Material and Methods

Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers'' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified.

Results

No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups.

Conclusions

Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.     

Visceral Leishmaniasis Complicating Polycythemia Vera

Abstract. A case of visceral leishmaniasis is presented, where a pre-existing polycythemia vera obscured signs of the infection. Visceral leishmaniasis is a life-threatening but curable protozoan infection of the reticuloendothelial system. We wish to report a case where symptoms and signs were obscured by a preexisting hematologic disease, polycythemia vera.     

Choosing the Stimulation Rate in Patients with Intermittent Bradycardia and a Single Lead Pacemaker

In order to assess the prevalence of intermittent bradycardia in a pacemaker population, we retrospectively evaluated the occurrence of intrinsic heart activity in 229 patients with ventricular pacing. Spontaneous heart activity was recorded in 60% of the patients. However, the stimulation rate had been decreased in onJy 40% of the patients in order to allow for longer periods of intrinsic heart activity. In the second part of the study we prospectively assessed differences in pacemaker utilization in 19 patients with intermittent bradycardia and single lead pacemakers. All patients were observed over four periods of 14 days, with the following pacing modes: 70 heats/min, 50 beats/min, hysteresis sensing 50 beats/min, and pacing 70 heats/min; and search hysteresis sensing 50 beats/min and pacing 70 beats/min. Search hysteresis pacing is a new feature that theoretically allows for a shorter time of pacing than that of hysteresis pacing. A reduction in the stimulation rate from 70 beats/min to 50 beats/ min resulted in a 60% reduction in pacemaker utilization (P < 0.05). Search hysteresis decreased pacemaker utilization by 33% (P < 0.05) There was no statistical difference between conventional hysteresis and fixed rate pacing at 70 beats/min. Most patients found fixed rate pacing preferable to hysteresis pacing. In order to minimize battery consumption and to avoid unfavorable hemodynamics in patients with ventricular pacing, the stimulation mode and rate should be optimized in patients with intermittent bradycardia to allow for longer periods of intrinsic heart activity.     

Rate Hysteresis Pacing: How Valuable Is It? A Comparison of the Stimulation Rates of 70 and 50 Beats per Minute and Rate Hysteresis in Patients with Sinus Node Disease

The main disadvantages of VVI pacing are absence of acceleration of the heart rate and loss of atrial synchronization. The alternatives to AAI and DDD pacing are stimulation at a low rate or hysteresis in order to decrease pacing time and thus reduce AV asynchrony. Nine patients who suffered from sinus node disease and who had been given a multiprogrammable pacemaker were monitored at each of three stimulation rates: 70, 50, and 70 bpm with an inhibition rate of 50 bpm (hysteresis).
The total pacing time was shortest (p < 0.05) for the stimulation rate of 50 bpm as compared to 70 bpm and hysteresis. It was also shorter for the hysteresis mode than for the 70 bpm mode (p < 0.05).
Only for hysteresis pacing was there a significant reduction in the number of changes from conducted cardiac rhythm to pacemaker-induced rhythm. Most patients found the 50 bpm mode preferable. None favored the hysteresis mode.
In patients with sinus node disease and intermittent bradycardia being permanently paced, the periods of AV-conducted rhythm may be lengthened by reducing the stimulation rate from 70 bpm, with or without hysteresis pacing, to 50 bpm. In paced patients with sinus node disease and symptoms due to AV asynchrony, it might be worth trying a decrease in the stimulation rate before resorting to other pacemaker systems.     

MOLECULAR ACTIONS OF RACEMIC KETAMINE ON HUMAN CNS SODIUM CHANNELS

In search of a molecular site and mechanism of action for anaesthetics,we have examined the effects of racemic ketamine on single humanCNS sodium channels with the new planar lipid bilayer technique.In the dose range studied (0.05–9.2 mmol litre^–1)ketamine depressed in a dose-dependent manner two major functionsof the sodium channel, by reducing the fractional open timein a voltage-independent manner (ED₅₀ 1.1 mmol litre^–1;maximal conductance block 71 %) and by interfering with thevoltage-dependent, steady-state activation. These actions occurredat concentrations which were greater than those used clinicallyin general anaesthesia (up to 0.02 mmol litre^–1), thereforethey reflect local rather than general anaesthetic effects whichmay be related to the hydrophobic properties of ketamine. Incomparison with two other i.v. anaesthetic agents, pentobarbitoneand propofol, racemic ketamine behaves differently at both themolecular and the clinical level. ^*Present address: Institut fur Anasthesiologie der RheinischenFriedrich-Wilhelms-Universitfit Bonn, Sigmund-Freud-Str. 25,D-W 5300 Bonn 1, Federal Republic of Germany      

Lability of N-alkylated peptides towards TFA cleavage

Trifluoroacetic acid (TFA) is a common reagent in both solid-phase and solution peptide synthesis. It is used for the deprotection and/or cleavage of the synthesized peptide from the resin. The use of TFA under these standardized conditions is thought to be sufficiently mild, thereby preventing degradation of the desired product. However, peptides of the general structure R¹-(N-alkyl X₁)-X₂-R² are hydrolyzed by standard TFA solid-phase peptide synthesis (SPPS) cleavage/deprotection conditions providing fragments R¹-(N-alkyl X₁)-OH and H-X₂-R². The fragmentation is observed during a TFA cleavage both from the resin and in solution. The hydrolysis is proposed to proceed via an oxazolone-like intermediate in which equilibration of the chiral center of the N-alkylated residue occurs. This mechanism is supported by H/D exchange as observed by MS and NMR in conjunction with HPLC. © Munksgaard 1996.     

Unemployment and change of tobacco habits: a study of young people from 16 to 21 years of age

In a cohort study of 1080 pupils who were followed for 5 years from when they left compulsory school (from age 16 to age 21 years), smoking habits were found to correlate with unemployment among both boys and girls. Pupils who zuere smokers in school had a higher risk of becoming unemployed than non-smokers. Irrespective of early smoking, smoking habits developed more unfavourably among unemployed young people than among those with no unemployment during the period studied. The odds ratio of being a smoker at the age of 21 years when unemployed more than 20 weeks during the observation period, compared with those without or with short unemployment, was 2.44 for men and 3.45 for women. When adjusted for the influence of socio-economic background, education, economy and smoking habits at the start of the period, the odds ratio was 1.7 (95% CI 1.01 2.86) for men and 2.0 (1.13–3.53) for women. The adjusted odds ratio for increasing or starting smoking during the period was 1.5 (95% CI 0.89-2.56) for men and 2.0 (1.18–3.35) for women. No significant correlation was found between snuffing and unemployment. Thus, it seems that unemployment is a risk factor for development of tobacco smoking in young people, especially among women.