Biology of Borrelia species.

Publisher Summary This chapter reviews that titration curves do not represent just another way of physically characterizing a protein molecule. More than most other physicochemical methods that are in common use, titration studies tend to emphasize individual differences among proteins, and this is reflected in the chapter. The chapter contains experimental procedures of general utility in the determination of titration data. The foundation for any study of hydrogen ion dissociation in proteins is the electrometric titration curve. To obtain such a curve, one begins with a protein solution of known concentration, at an arbitrary reference pH, adds to it varying amounts of a strong acid or a strong base, and then measures the new pH attained. In a separate experiment, or by means of calculations based on similar experiments, one determines how much acid or base is needed to take a solution, which does not contain protein, but otherwise has the same initial pH, ionic strength, and volume. The difference between the two amounts is the amount of acid or base that is bound to the protein in going from the reference pH to the final pH: a plot of this quantity versus the final pH is the desired titration curve. In plotting this curve, OH - ions bound are counted as H + ions dissociated a procedure, which is always permissible in aqueous solutions.

The Interpretation Of Hydrogen Ion Titration Curves Of Proteins

Extracellular matrix-based biomaterial scaffolds and the host response

The pathogenic potential of Fusobacterium nucleatum and its significance in the development of periodontal diseases, as well as in infections in other organs, have gained new interest for several reasons. First, this bacterium has the potential to be pathogenic because of its number and frequency in periodontal lesions, its production of tissue irritants, its synergism with other bacteria in mixed infections, and its ability to form aggregates with other suspected pathogens in periodontal disease and thus act as a bridge between early and late colonizers on the tooth surface. Second, of the microbial species that are statistically associated with periodontal disease, F. nucleatum is the most common in clinical infections of other body sites. Third, during the past few years, new techniques have made it possible to obtain more information about F. nucleatum on the genetic level, thereby also gaining better knowledge of the structure and functions of the outer membrane proteins (OMPs). OMPs are of great interest with respect to coaggregation, cell nutrition, and antibiotic susceptibility. This review covers what is known to date about F. nucleatum in general, such as taxonomy and biology, with special emphasis on its pathogenic potential. Its possible relationship to other periodontal bacteria in the development of periodontal diseases and the possible roles played by OMPs are considered.

Taxonomy, biology, and periodontal aspects of Fusobacterium nucleatum.

Bone sialoprotein (BSP) is a phosphorylated and sulfated glycoprotein that is a major noncollagenous protein of bone and other mineralizing connective tissues BSP is characterized by the presence of several polyglutamic acid segments and an RGD motif that mediates cell attachment through a vitronectin-like receptor Although the precise function of BSP is unknown, the expression of BSP in conjunction with bone formation in vitro indicates a role for this protein in the biomineralization of connective tissues In this study we used Northern hybridization and in situ hybridization to determine the tissue-specific and developmental expression of BSP during embryogenesis and growth of rat tissues Analysis of tissues obtained from 13, 17, and 21 day fetuses, and from 4-, 14-, and 100-day-old animals indicates that BSP mRNA expression is restricted to cells actively forming the mineralizing tissues of bone, dentin and cementum BSP mRNA transcripts were first evident in fully differentiated osteoblasts of 17 day fetal tissues at sites of de novo intramembranous and endochondral bone formation, with maximal expression observed at 21 days of gestation Thereafter, BSP mRNA levels decreased markedly, and in adult bone hybridization was detected only in the primary spongiosa of long bones In comparison, mRNAs for osteopontin (OPN), alkaline phosphatase (ALP), and osteocalcin (OC) peaked at 4-14 days postpartum before declining In the tibiae, Northern hybridization revealed a second peak of mRNA for BSP, ALP, and OPN at 14 days, reflecting an increased osteogenic activity due to the formation of the secondary centers of ossification in the epiphyseal cartilage In situ hybridization also revealed BSP mRNA in hypertrophic chondrocytes at sites of bone formation, in odontoblasts of the incisor during dentinogenesis, and in cementoblasts during cementogenesis In view of the restricted distribution and temporal changes in the expression of BSP mRNA that we observed together with the chemical properties of BSP, we believe that this protein has a specific role in mediating the initial stages of connective tissue mineralization

Developmental expression of bone sialoprotein mRNA in rat mineralized connective tissues

SummaryExperimental 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 ...

Mineralization of Dental Calculus.

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

The principal findings during the first decade of electron microscopy of dental tissues have been summarized in a recent review publication.' In that paper, all of the available literature was cited, and emphasis was laid upon the structural variations which have been universally observed in normal, mature enamel and dentin. Some of these variations, like those which occur in the contours of enamel prisms when viewed in cross section, are not new to microscopists, for they have long been seen under the optical microscope. Other variations, such as those that exist in the organic matrix of the enamel, would not have been demonstrable except by use of the higher resolving power of the electron microscope. The impact of such observations with the electron microscope on existing histological concepts has been the realization that the structures of enamel and dentin are considerably more complex than was hitherto believed. Instead of leading directly to a clearer understanding of the basic structural units of enamel and dentin, these more detailed findings have increased the difficulty of interpretation. In the present paper, some of the major areas in which information on the structure of enamel and dentin is still incomplete will be pointed out, and the contributions to present-day knowledge being made through investigations with the electron microscope will be discussed a t some length. The most fundamental problem in histological studies of enamel continues to be exact definition of the basic structural unit. There is little question today that mature human enamel is made up almost entirely of prismatic structures, extending individually from the dentino-enamel junction to the surface of the tooth and, for the most part, lying parallel to each other.2 Investigations of developing enamel have indicated quite conclusively that each prism is hid down by a single ameloblast, which progresses outwardly in the course of enamel formation from a point of junction with the layer of odontoblasts to the contour line of the fully-formed crown of the tooth.3 Taken together, such facts suggest that the prism is the structural unit of enamel. Even though the enamel prism has a diameter of ca. five microns, and is thus well within the limits of resolution of the optical microscope, it has not been possible to derive an accurate, all-encompassing description which can be applied to prisms in general. In the most widely accepted working concept of enamel structure, the prism is considered as a long filament, roughly hexagonal, round or scale-shaped (arcade-shaped) in cross section, surrounded by a thin organic sheath, and separated from neighboring prisms by varying amounts of cementing or interprismatic substance. The inadequacies of such a definition have long been realized, principally because of the marked diffcrcnces in appearance between regions of hexagonal or round prisms and regions of scale-shaped prisms. In the former areas, the prisms appear well demarcated, entirely surrounded by sheaths and definitely separated from each other by interprismatic material. In the latter

The electron microscopy of enamel and dentin

Knowledge of spirochetal morphology has been gained for the most part by systematic studies of material from infected hosts and in certain instances from pure cultures maintained in the laboratory on artificial culture media. In this regard the hanging drop preparation, the stained smear or section, and dark-field illumination of wet preparations have been used to advantage. The last method has been more universally employed by the exacting investigator to demonstrate the fine structural differences that exist between the various types of spirochetes. The members of the genera Treponema and Borrelia present morphologic and structural features that have been the subject of considerable speculation and controversy for many years. In this laboratory the electron microscope has been used to demostrate some of these controversial structures, and the present paper describes certain results thus far obtained. Eight strains of spirochetes have been used. Two of these were strains of the small oral treponemes identified as FM and MRB; four were strains of Borrelia vincentii, designated as N9, N19, N37, and CON; and two were cultured strains of Treponema pallidum denoted as Nog and Ni (the Noguchi and Nichols strains). The small oral treponemes were morphologically and culturally similar in all details and representative of our collection of this type of spirochete. Under dark-field optical illumination, they showed uniform and closely spaced spirals and had long tapered ends. They were not double contoured. The four strains of B. vincentii were morphologically and culturally similar to one another and were approximately one and one-half times the size of the smaller oral treponemes. By dark-field examination these spirochetes had large, uniform, and widely spaced coils. The extremities were abruptly tapered and the organisms were not double contoured. The strains of T. pallidum were culturally similar to one another; the organisms had uniform and closely spaced spirals and long tapered ends and were not double contoured. In this they resembled the oral treponemes, but were on the average about one and one-half times as long. All spirochetes were grown in a clear liquid medium which is a modification of a "hormone" agar described by Huntoon (1918). This modified broth is essen-

Morphologic Characteristics of Certain Cultured Strains of Oral Spirochetes and Treponema pallidum as Revealed by the Electron Microscope.

An electron microscopic study of the early stages of dentinogenesis

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