Surface properties and castability of elastomeric impression materials after plasma cleaning.

The wettability of impression materials is an important requirement for accurate reproduction of intraoral structures. The aims of this study were to evaluate the effect of plasma cleaning on critical surface tension and die stone castability of five silicone impression materials. Critical surface tension was calculated using a contact angle analysis according to Zisman (1964), before and after plasma cleaning. Die stone casts were produced from impressions of a master die and the area extension of the reproduction was measured planimetrically. The results showed a general increase in the critical surface tension and in the polar force component of the composite free energy for materials treated with plasma cleaning. An improvement in castability of all materials was also noted.     

Determinants of dietary intake during childhood diarrhea and implications for appropriate nutritional therapy

Diarrheal diseases have a well recognized negative effect on children's growth, probably due in part to reduced dietary intake during illness. Previous studies have shown that the effects of diarrhea on dietary intake are greater among hospitalized children than among those observed in their homes. Breast milk intake does not change during diarrhea, however, so breast-fed children are less likely to reduce their total energy and nutrient intakes. Recent analyses of clinical studies found that acidosis and dehydration were most closely associated with reduced dietary intake of hospitalized patients. The implications of these and other studies for the dietary management of patients during and after diarrhea are discussed.     

Composite chondroperichondrial clip tympanoplasty: the triple "C" technique.

OBJECTIVES: The study goal was to assess the success rate and efficacy of a myringoplasty (tympanoplasty type I) technique using a composite chondroperichondrial graft in a combined overlay-underlay fashion. STUDY DESIGN: A retrospective analysis of patients subjected to the technique was conducted. METHODS: A sample of 15 patients who met the inclusion criteria were reviewed for surgical results. All patients were treated by a single surgeon. RESULTS: This transcanal technique provides minimal morbidity and excellent results in selected patients. CONCLUSIONS: The described technique provides an effective method of closing nonmarginal perforations of the tympanic membrane.     

Cognitive profiles of individual patients with Parkinson's disease and dementia: comparison with dementia with lewy bodies and Alzheimer's disease.

We describe the pattern of cognitive profiles within a community-based sample of patients with Parkinson's disease (PD) and dementia (PDD) using cluster analyses, and compare the results with data from patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Fifty patients with PDD and 39 with AD from Stavanger, Norway, and 62 patients with DLB from San Diego, CA, USA were diagnosed by either standardized clinical procedures or criteria (all PDD and all AD cases) or necropsy (all DLB cases). Four subgroups were identified: two subgroups with a subcortical cognitive profile (one with mild and one with moderate dementia severity), one subgroup with global impairment and severe dementia, and one subgroup with a cortical cognitive profile and moderate dementia. Of the patients with PDD and with DLB, 56% and 55%, respectively, had a subcortical cognitive profile, compared with only 33% of the AD patients. Conversely, 30% of the patients with PDD and 26% of those with DLB had a cortical cognitive profile, compared with 67% of the patients with AD. These findings suggest that in some patients with PDD, frontosubcortical changes are the main contributing factor to dementia, whereas in other patients, cortical and hippocampal changes are more important.     

Importance of spatiotemporal heterogeneity of cellular restitution in mechanism of arrhythmogenic discordant alternans

BACKGROUND: Spatially discordant cellular alternans form a substrate for development of unidirectional block and ventricular fibrillation. However, the mechanisms responsible for discordant alternans remain poorly understood. Previous work suggests electrical restitution is critical to the development of alternans in single cells. OBJECTIVES: The purpose of this study was to investigate the hypothesis that spatial and temporal heterogeneities of restitution underlie the mechanism eliciting discordant alternans. METHODS: Steady-state pacing was used to elicit concordant cellular alternans in nine Langendorff-perfused guinea pig hearts. A single extrastimulus (S2) was applied every 51st beat following either the even or the odd beat of alternans. The cellular response to S2 was determined using optical mapping to generate action potential duration (APD) restitution curves from 256 ventricular sites for both the even and the odd beats. RESULTS: Restitution kinetics were temporally heterogeneous during alternans, as restitution curves between the even and the odd beats differed significantly. Temporal heterogeneity was quantified by the average separation of restitution between the two curves, or Delta-restitution. Delta-Restitution was spatially heterogeneous and proportional to the amount of alternans at a given ventricular site. A computer simulation based on the experimental results showed the mechanism of discordant alternans was dependent on both spatial and temporal heterogeneities of restitution. CONCLUSION: Both temporal and spatial heterogeneities of restitution exist during cellular alternans in the intact heart. Temporal heterogeneities of restitution, quantified by Delta-restitution, are proportional to the magnitude of cellular alternans. The combination of spatial and temporal heterogeneities of restitution may underlie the genesis of discordant alternans.     

LIMITATIONS OF RADIOTHERAPY IN THE DEFINITIVE TREATMENT OF SQUAMOUS CARCINOMA OF THE TONSILLAR FOSSA

Between 1970 and 1990, 104 patients with squamous cell carcinoma (SCC) of the tonsil were treated. The median age was 58 years and 80% of patients were males. Distribution among clinical stages was: stage I, 19 patients; stage II, 12 patients; stage III, 23 patients; and stage IV, 48 patients. More than 70% of patients had initial radiotherapy as definitive treatment irrespective of stage, reflecting the treatment philosophy over much of this period. The overall survival rate was 26% at 5 years, with survival being significantly affected by T stage, clinical stage and age. Clinical node status did not significantly affect survival rates. Good local control of T₁N₀ cancers was achieved with radiotherapy alone, but patients with more advanced cancers did poorly. We have now moved away from a non-selective policy and use initial surgery combined with postoperative radiotherapy in most patients, reserving radiotherapy alone for mainly early tonsil cancers.     

Treatment of experimentally induced atherosclerosis in swine iliac arteries: A comparison of self-expanding and balloon-expanded stents

Atherosclerosis was induced in 20 Hanford miniature swine. Subsequently, one iliac artery lesion in each of 16 pigs was stented with either a self-expanding (8 pigs) or a balloon-expanded (8 pigs) stent. Immediately after stent placement, 4 animals in each group were taken off the atherogenic diet and continued on normal chow for the remainder of the study. Four months after stents were placed, atherosclerosis and the mural changes associated with the stent were more clearly evident in the arteries of the pigs continued on the atherogenic diet. These pigs also exhibited significantly more neointimal proliferation. In addition, the arteries containing the balloon-expanded stents showed more extensive and complex intimal changes when compared with arteries with self-expanding stents. Although both stent designs were equally effective in maintaining vascular patency, the balloon-expanded stent was more traumatic to the vessel wall which resulted in a significantly greater neointimal thickness.