An In Vitro Comparison of New Irrigation and Agitation Techniques to Ultrasonic Agitation in Removing Bacteria From a Simulated Root Canal

IntroductionThis in vitro study compared 3 agitation and 2 irrigation devices to ultrasonic agitation at mechanically removing bacteria from a plastic simulated canal, instrumented to 35/.06.MethodsThe plastic blocks were divided into seven groups. The control (C) group with brain-heart infusion (BHI) broth (sterile) received only needle irrigation. The remaining groups were incubated with BHI inoculated with Enterococcus faecalis. Irrigation and agitation techniques were ultrasonic, needle irrigation, EndoVac irrigation (Smart Endodontics; Discus Dental, Culver City, CA), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK), F-File (Plastic Endo, Lincolnshire, IL), and sonic. Sterile water was the irrigant in all treatments. Remaining bacteria were stained with 0.1% crystal violet. The crystal violet was extracted using a detergent and measured spectrophotometrically.ResultsThe results of this study show that ultrasonic agitation was not significantly different (p > 0.05, Tukey test) from the control. There was no significant difference (p > 0.05, Tukey test) between the ultrasonic agitation and the use of EndoActivator, F-File, and sonic agitation. Ultrasonic agitation was significantly more effective at removing bacteria than needle irrigation and EndoVac irrigation (p < 0.05, Tukey test).ConclusionIn a plastic simulated canal, ultrasonic agitation was significantly more effective than needle irrigation and EndoVac irrigation at removing intracanal bacteria. Ultrasonic, EndoActivator, F-File, and sonic agitation are similar in their ability to remove bacteria in a plastic simulated canal.     

The effect of age on small bowel adaptation and growth after proximal enterectomy.

We examined the effect of age on the adaptive capacity of small bowel mucosa following 60% enterectomy. Two groups of male Fischer 344 rats (3 mo old and 26 mo) underwent either a mid-small bowel transection and reanastomosis (control) or 60% proximal enterectomy beginning at the duodenojejunal junction. Rats were sacrificed at 5, 14, and 21 days after operation, and the mucosa was weighed and assayed for DNA, RNA, protein, and polyamine concentration and content. Ornithine decarboxylase activity was also measured in ileal mucosa at 5 days after surgery. Young rats had completed the adaptive hyperplastic response within 2 weeks after operation by all biochemical measurements; similar adaptation was not seen until 3 weeks after operation in the old rats. We conclude that although the capacity to achieve intestinal adaptation after enterectomy is preserved into old age in rats, this compensatory response is delayed.     

Lavage versus serum measurements of lysozyme, angiotensin converting enzyme and other inflammatory markers in pulmonary sarcoidosis

The aim of this study was to explore whether amounts of angiotensin converting enzyme (ACE) and lysozyme produced within the lungs correlate more closely than serum levels of these enzymes, or other inflammatory markers, with chest radiographic profusion scores, lung function and therapy response in patients with pulmonary sarcoidosis. We have studied 25 patients, and levels in bronchoalveolar lavage (BAL) were used to determine "local" enzyme production by reference to serum and lavage albumin. Before treatment, serum lysozyme levels were elevated in more patients (80%) than serum ACE levels (40%). They also gave the best overall correlation with clinical measurements prior to treatment and falls in serum lysozyme closely parallelled improvement in lung function (transfer factor for carbon monoxide (DLCO)) on therapy. The only other markers showing significant correlations with disease severity were lavage neutrophil counts per ml and "local" ACE measurements prior to treatment. The value of pre-treatment levels of the different inflammatory markers in predicting response to corticosteroid therapy was explored and the only significant finding was that BAL lymphocyte percentages and numbers.ml-1 were initially higher in patients with lower post-treatment chest X-ray scores (p less than 0.01 and p less than 0.05, respectively). We conclude that serum lysozyme levels appear to be a more useful marker of overall disease activity in sarcoidosis than measurements of other inflammatory markers. However, BAL lymphocyte counts were the best predictive marker of radiographic response to corticosteroids.     

Evaluation of the molecular epidemiology of an outbreak of multiply resistant Shigella sonnei in a day-care center by using pulsed-field gel electrophoresis and plasmid DNA analysis.

Outbreaks of diarrhea in child day-care centers (DCC) are common. This study was undertaken to evaluate the molecular epidemiology of an outbreak of diarrhea due to Shigella sonnei. This outbreak involved 25 of 52 (48%) DCC children and 14 of 132 (11%) teachers and household contacts. S. sonnei isolates from nine children and five contacts were characterized by antimicrobial susceptibility, plasmid content, plasmid DNA restriction fragment pattern, and pulsed-field gel electrophoresis (PFGE) of total genomic DNA; 33 isolates from Houston, Tex., Chicago, Ill., and Mexico City, Mexico, also were studied. All outbreak isolates were resistant to ampicillin and trimethoprim-sulfamethoxazole and shared five to six plasmids ranging from 3.3 to 70 MDa. A total of 8 of 12 temporally associated nonoutbreak Houston isolates had plasmid profiles and restriction fragment patterns similar to those of the outbreak strain, despite possessing different antibiotic susceptibility patterns. PFGE demonstrated identical DNA patterns among outbreak isolates and similar or identical patterns among temporally associated sporadic Houston isolates with plasmid profiles similar to that of the outbreak strain. All other nonoutbreak strains from Houston, Chicago, and Mexico had plasmid profiles, restriction fragment patterns, and PFGE patterns different from those of the outbreak strain. DCC outbreak isolates could be distinguished from most sporadic isolates by antimicrobial susceptibility testing, but plasmid analysis and PFGE could not differentiate common-source isolates from sporadic isolates in the same location during the same time period, indicating that isolates present in the community were genetically similar to those producing outbreaks in the DCC.     

Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups.

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.     

Hypopigmentation in Angelman syndrome

Chromosome region 15q is thought to contain one or more genes that are important for melanin pigment synthesis in the hair, skin, and eyes. Hypopigmentation has been identified in the Prader-Willi (PWS) and Angelman (AS) syndromes. We have examined 6 individuals with AS to further characterize the pigment pattern in this condition. The age of the 5 girls and one boy ranged from 2.4 to 7.0 years. None has obvious albinism. Hair color ranged from light blond to brown. Skin was type I in 3 and type II in 3. Eye changes included nystagmus in 2, strabismus in 4, and reduced retinal pigment in 5. The mean hairbulb tyrosinase activity was 0.37 ± 0.44 pmol/hb/120 min for the individuals with AS, with a range of 0.00 to 1.13 (normal brown control 1.49 ± 0.79, normal blond control 1.50 ± 0.85). Electron microscopic examination of hairbulb melanocytes showed normal melansome and melanocyte architecture and number, but reduced melanin formation, with many stage II and III premelanosomes but few stage IV fully melanized melanosomes. Hypopigmentation characterized by light skin, reduced retinal pigment, low hairbulb tyrosinase activity, and incomplete melanization of melanosomes is part of the phenotype of AS, and is similar to that found in PWS. © 1993 Wiley-Liss, Inc.     

Effects of calcium channel blockade on calcium homeostasis in mild to moderate essential hypertension

Calcium channel blockers may alter parathyroid hormone secretion in vitro, which would alter calcium homeostasis. To determine the chronic effect of calcium channel blockade in vivo, we conducted a randomized, double blind, 16 week study comparing the effects of two pharmacologic antihypertensive agents, the calcium channel blocker diltiazem and the angiotensin-converting enzyme inhibitor captopril on parameters of calcium homeostasis. Both diltiazem and captopril lowered blood pressure to a similar degree. Neither drug produced any significant change in blood levels of total and ionized calcium, magnesium, or phosphorus, which affect the regulation of parathyroid hormone and vitamin D. In addition, at eight or 16 weeks following initiation, neither drug altered the serum levels of parathyroid hormone (PTH) or 1,25-(OH)2-vitamin D3 (1,25-D). Chronic calcium channel blockade with diltiazem does not alter serum parameters of calcium homeostasis and, thus, should not affect bone mineralization.     

PET/CT artifacts

There are several artifacts encountered in positron emission tomography/computed tomographic (PET/CT) imaging, including attenuation correction (AC) artifacts associated with using CT for AC. Several artifacts can mimic a 2-deoxy-2-[18F] fluoro-d-glucose (FDG) avid malignant lesions and therefore recognition of these artifacts is clinically relevant. Our goal was to identify and characterize these artifacts and also discuss some protocol variables that may affect image quality in PET/CT.