Debate continues as to the role that bacteria play in gallstone pathogenesis in Western countries. We therefore, examined gallbladder and common duct stones from 67 consecutive patients undergoing cholecystectomy and/or common bile duct exploration. Bile was cultured and stone cholesterol content was measured. Stones were examined by scanning electron microscopy (SEM) for bacteria. Individual calcium salts were classified by windowless energy-dispersive x-ray microanalysis. Gallbladder stones in 65 patients were identified as cholesterol in 46 (71%), black pigment in 17 (26%), and brown pigment in 2 patients (3%). Common bile duct stones from ten patients were cholesterol in 4, black pigment in 2, and brown pigment in 4 patients. The five patients with brown pigment stones were significantly (p less than 0.05) older, more likely to be men and to present with bile duct obstruction. Bile cultures were positive in 13% of patients with cholesterol stones, in 14% of those with black pigment stones, and in all of the patients with brown pigment stones (p less than 0.001). By SEM, bacteria were observed only within the calcium bilirubinate-protein matrix of brown pigment stones (p less than 0.001). In comparison to black pigment stones, brown stones were more likely to contain calcium palmitate (p less than 0.005) and cholesterol (p less than 0.001). We conclude that black and brown pigment stones have different pathogenic mechanisms and that bacterial infection is important only in the formation of brown pigment stones.

The level of pyridine nucleotides (NADH and NAD+) in the mineralizing growth plate of the chick was ascertained by high-resolution scanning microfluorimetry and biochemical analysis. Scanning electron microscopy and light microscopy were used to relate the concentrations of NADH and NAD+ to stages of chondrocyte maturation. A dramatic increase was found in the relative concentration of reduced pyridine nucleotides in the hypertrophic zone. On either side of this zone, in proliferating and calcifying cartilage, there was a decrease in NADH fluorescence, and the NADH/NAD+ ratio was depressed. The finding that NADH accumulated in the tissue zone associated with the earliest deposition of bone mineral supports the hypothesis that a change in the redox state initiates tissue mineralization.

Frasca P. Effectiveness and safety of a sonic vibratory endodontic instrument. Endod Dent Traumatol 1985; 1: 69-76.Abstract -An air-driven sonic vibratory handpiece to which specially designed K-type fifes are attached has been developed. When activated, the root canal instruments will vibrate in a whirling motion, and when moved up and down, will abrade the root canal wall. The sonic system was tested in simulated root canals in plastic blocks and in usage tests iu dogs' teeth. Fortynine roots in 3 dogs were divided into 3 groups. Two of the groups were instrumented with the sonic device under continuous irrigation with 2.5% NaOCl or 15% EDTA. The 3rd group was treated with conventional chemomechanical instrumentation and 2.5% NaOCl. The teeth were then extracted, fi.xed and split in a longitudinal direction and the root canals examined in the scanning electron microscope. After hand instrumentation and sonic instrumentation using NaOCl for irrigation, the canal wall was covered by a smear layer and dentin chips and occasional tissue remnants were seen. An extraoral fine mist of NaOCl was seen during continuous irrigation with this medicament, causing eye soreness in the operator. Continuous irrigation with EDTA during sonic instrumentation removed the smear layer and gave clean canal walls. The vibratory files appeared safe and size 20 followed curved canals well. The effectiveness of the sonic device was similar to hand instrumentation. It considerably improved tbe ease and, to some extent, the speed of root canal instrumentation.

Adult human cortical bone was decalcified and stained with Harris’s hematoxylin, which has a strong affinity for cement lines, resting lines, hypercalcified rings and reversal lines. Small pieces of bone tissue containing these morphological entities were then dissected and manipulated mechanically so as to disrupt them partially. Scanning electron microscopy of these regions of interest revealed the presence of relatively large concentrations of amorphous ‘ground substance’ which was morphologically distinguishable from the fibrous collagen fiber bundles located in the adjoining collagen-rich lamellae. The methodology used in this study confirms the existence of the above-mentioned regions as true morphological entities and also makes possible enzymatic studies designed to identify the major biochemical components constituting the observed ‘ground substance’.

Calcium bilirubinate, palmitate, carbonate and phosphate have been identified in the cores of cholesterol and pigment gallstones, suggesting a role for precipitated calcium salts in the early events of gallstone formation. Previous studies that compared the calcium salt contents of cholesterol and pigment stones required destruction of gallstone structure. We have used scanning electron microscopy with windowless energy-dispersive x-ray microanalysis to determine the prevalence of calcium salts in a series of cholesterol (n = 105), black pigment (n = 35) and brown pigment (n = 6) gallstones obtained from 146 consecutive patients undergoing cholecystectomy. These techniques provide specific identification of cholesterol and individual calcium salts as they occur within the core, periphery and shell of gallstones without destroying stone structure. Calcium precipitates more than 0.5 micron in diameter can be detected in a cholesterol background at a detection limit of 0.01% by weight. Calcium salts were detected in the centers of 88% of cholesterol and 100% of black (p < 0.05 vs. cholesterol) and brown pigment stones. Calcium bilirubinate was identified in the cores of 54% of cholesterol and in all pigment stones (p < 0.001 black pigment vs. cholesterol). Calcium palmitate was detected in all brown pigment stones, in 39% of cholesterol stones (p < 0.001 vs. brown pigment) and in 31% of black stones (p < 0.01 vs. brown pigment). Peripheral calcium salts were detected less in cholesterol (19%) than in black or brown stones (100%, p < 0.05). Fourteen percent of cholesterol and black pigment stones were surrounded by shells containing mostly calcium carbonate.(ABSTRACT TRUNCATED AT 250 WORDS)