David B. Scott

Observations on function, composition, and structure of cestode calcareous corpuscles

Abstract 1. 1. Taenia taeniaeformis contains about half as much calcareous corpuscle material as does Cysticercus fasciolaris. The corpuscles show no quantitative gradient along the strobila of Taenia taeniaeformis, but the larger individual proglottids contain more corpuscle material than the smaller ones. 2. 2. More calcareous material disappears from Cysticercus faciolaris during anaerobic than during aerobic incubation in non-nutritive media. In both cases considerably more corpuscle material disappears when the worms are incubated in slightly acid than in slightly alkaline surroundings. It is concluded that the corpuscles serve to buffer acids entering the body from the outside and, possibly, to buffer acids produced during aerobic and anaerobic fermentations. 3. 3. The corpuscles yield Ca, Mg, P, and CO2. The mineral component of the corpuscles is amorphous, but upon heating with KOH crystallization takes place and brucite and hydroxyapatite crystals are formed. The carbonates, however, do not crystallize. 4. 4. Electron microscopy indicates that the lamellae of the corpuscles may be paired rings. It reveals also an amorphous or granular background substance, but no crystalline elements. 5. 5. The inorganic material of the corpuscles can readily be demonstrated by various histochemical staining methods. It is also possible to demonstrate histochemically a glycogen-like polysaccharide, a mucopolysaccharide, lipids, and proteins as constituents of the organic base of the corpuscles.

Mineralization of dental calculus.

Summary Experimental studies have been made of mineralization in developing human dental calculus, formed in vivo on polyester strips attached to the teeth. The findings suggest a close parallelism between calcification process in this exogenous deposit and in calcified tissues. The microorganisms and intermicrobial substance first laid down serve as the organic matrix, which undergoes a series of chemical and morphological changes prior to mineralization. Calcification within this matrix follows a definite pattern, crystals first being laid down between and on surfaces of the bacteria, and later inside them.

Mineralization of Bacteria

A variety of viable and non-viable bacteria became mineralized with hydroxyapatite when implanted in dialysis bags in the peritoneal cavities of rats. The microscopic pattern of mineral deposition appeared analogous to that in the formation of oral calculus. Since nonviable organisms were mineralized at an accelerated rate, bacterial metabolic processes may not be essential for mineralization.

Variations in the mineralogical composition of cestode calcareous corpuscles

Abstract 1. 1. The calcareous corpuscles of Cysticercus cellulosae , larval Spirometra mansonoides , Taenia saginata , and Diphyllobothrium latum contain various proportions of calcium, magnesium, phosphorus, and CO 2 as major components. 2. 2. The corpuscles of these worms, and those of the previously studied Taenia taeniaeformis , contain in addition several minor inorganic constituents. The corpuscles of the larval worms show a smaller variety of the minor components than those of the adult worms. 3. 3. The crystallization patterns induced by heat or KOH treatment vary, especially in respect to the phosphorus-containing compounds. Three of the latter have been identified: Hydroxyapatite, whitlockite, and calcium-magnesium-orthophosphate. The crystallization variations may be related to the ratios in which the major components occur in the corpuscles of the different species.

The mineralogical composition of the calcareous corpuscles of Taenia taeniaeformis.

Abstract 1. 1. The mineral content of calcareous corpuscles of cestodes is amorphous in vivo and consists primarily of Ca, Mg, P, and CO2. 2. 2. The results of a series of heat and chemical transformations of isolated Taenia taeniaeformis corpuscles and synthetic mixtures suggest that the major inorganic components of the native corpuscles are in the form of an amorphous calcium phosphate and an amorphous MgCaCO2 complex. 3. 3. The fact that still other inorganic constituents must be present is demonstrable not only from the analytical data but also from the isolation of a thermolabile fraction.

Electron microscopy of carious enamel and dentine

Abstract Techniques have been described by which thin sections for electron microscopy can be prepared from both undemineralized and artificially demineralized specimens of carious enamel and dentine. Observations on the typical appearance of these tissues have been reported and illustrated with representative electron micrographs. The relation of the findings to present concepts on the histopathology of dental caries has been discussed.

Relation of ionizing groups to the structure of the collagen fibril.

Abstract The hydrogen ion concentration of the medium during the reconstitution of collagen markedly influences the structure of the resulting fibril. The pH at which such morphological alterations occur and the titration of fibrils formed at various pH levels suggest that the imidazole moieties may be involved in the alignment and binding of adjacent molecules in collagen fibrils characterized by a 640 A axial periodicity.

Microscopic studies of dental tissues. I. Electron microscopy of tooth structure

Abstract The applications of the electron microscope in the study of dental tissues have been described. Some of the results of the investigations of the structure of mature and developing enamel and dentine, and various other tissues, have been presented.

Observations on Calcareous Corpuscles of Larval Echinococcus granulosus of Various Geographic Origins

Summary Calcareous corpuscles isolated from larval Echinococcus granulosus collected from sheep in Chile and New Zealand and from cattle in Lebanon showed only minor differences in their chemical composition and their heat-induced crystallization patterns. The only definite differences found were that the Chilean material lacked manganese, and that it had a somewhat higher magnesium and a lower phosphorus content than the other samples. As a consequence of the relatively low phosphorus content the Chilean material yielded upon heating at most traces of apatite. Previously described much more pronounced differences in chemical composition and crystallization patterns between corpuscles from different tapeworm species are hence probably essentially species-specific.

Lysis by Human Oral Bacteria of Collagen Altered By Ethylene Oxide

Summary Treatment with ethylene oxide rendered reconstituted acid-soluble collagen readily digestible by combined pure cultures of human oral strains of fusiform bacilli, diphtheroid bacilli, streptococci, and veillonellae. The fact that only a few of these strains individually attacked such altered collagen to a slight extent indicates digestion by synergistic and symbiotic reactions between members of the oral microbiota. Concomitantly with increased digestibility from treatment with ethylene oxide, reconstituted collagen exhibited marked morphological changes as revealed by electron microscopy.