Biomedical applications of glyconanoparticles based on quantum dots.

BACKGROUND: Quantum dots (QDs) are outstanding nanomaterials of great interest to life sciences. Their conjugation versatility added to unique optical properties, highlight these nanocrystals as very promising fluorescent probes. Among uncountable new nanosystems, in the last years, QDs conjugated to glycans or lectins have aroused a growing attention and their application as a tool to study biological and functional properties has increased. SCOPE OF REVIEW: This review describes the strategies, reported in the literature, to conjugate QDs to lectins or carbohydrates, providing valuable information for the elaboration, improvement, and application of these nanoconjugates. It also presents the main applications of these nanosystems in glycobiology, such as their potential to study microorganisms, the development of diseases such as cancer, as well as to develop biosensors. MAJOR CONCLUSIONS: The development of glyconanoparticles based on QDs emerged in the last decade. Many works reporting the conjugation of QDs with carbohydrates and lectins have been published, using different strategies and reagents. These bioconjugates enabled studies that are very sensitive and specific, with potential to detect and elucidate the glycocode expressed in various normal or pathologic conditions. GENERAL SIGNIFICANCE: Produce a quick reference source over the main advances reached in the glyconanotechnology using QDs as fluorescent probes.

Short term inhalation toxicity of a liquid aerosol of CdS/Cd(OH)2 core shell quantum dots in male Wistar rats.

Colloidal quantum dots (QD) show great promise as fluorescent markers. The QD used in this study were obtained in aqueous medium rather than the widely used colloidal QD. Both methodologies used for the production of QD are associated with the presence of heavy metals such as cadmium (Cd). Here we investigate the short-term inhalation toxicity of water-soluble core-shell CdS/Cd(OH)2 QD. Male Wistar rats were head-nose exposed for 6 h/day on 5 days at the technically maximum concentration (0.52 mg Cd/m³). Histological examination was performed directly after the last exposure. Additional rats were used for Cd organ burden determinations. Clinical parameters in blood, bronchoalveolar lavage fluid and lung tissue were determined 3 days after the last exposure. To analyze the reversibility or progression of effects, the examinations were performed again after a recovery period of 3 weeks. The results of the study indicate that CdS/Cd(OH)2 QD caused local neutrophil inflammation in the lungs that partially regressed after the 3-week recovery period. There was no evidence that QD were translocated to the central nervous system nor that a systemic acute phase response occurred.

Distribution of biglycan and decorin in rat dental tissue

Biglycan and decorin are small leucine-rich proteoglycans that play several biological and structural roles in different tissues and organs. Several reports have indicated that biglycan participates in odontoblast and ameloblast differentiation and in the calcification process. In the present study we show that the expression of biglycan changes from within the ameloblasts and odontoblasts to the extracellular space according to the stage of animal development. In predentin and in the pulp space, however, biglycan was continually expressed throughout the period of investigation. In contrast, decorin was absent in odontoblasts and in ameloblasts and was exclusively expressed in predentin throughout the period of observation. In young rats, however, decorin was expressed in the extracellular spaces of the pulp, where it was concentrated mainly in the peripheral pulp

Distribution of biglycan and decorin in rat dental tissue.

Biglycan and decorin are small leucine-rich proteoglycans that play several biological and structural roles in different tissues and organs. Several reports have indicated that biglycan participates in odontoblast and ameloblast differentiation and in the calcification process. In the present study we show that the expression of biglycan changes from within the ameloblasts and odontoblasts to the extracellular space according to the stage of animal development. In predentin and in the pulp space, however, biglycan was continually expressed throughout the period of investigation. In contrast, decorin was absent in odontoblasts and in ameloblasts and was exclusively expressed in predentin throughout the period of observation. In young rats, however, decorin was expressed in the extracellular spaces of the pulp, where it was concentrated mainly in the peripheral pulp.

The modulatory role of cementum matrix on osteoblastic cells in vitro.

The formation of new cementum is an important issue in clinical periodontology, as cementum is required to provide attachment for newly formed periodontal tissues to the root surface. In this study a model of cementogenesis in vitro was used in order to test the effects of root surface demineralization on the migration, attachment and formation of a cementum-like tissue by osteoblastic cells cultured on cementum and to test the specificity of cementum matrix in modulating those effects by comparison of root co-cultures with bone co-cultures. It was demonstrated that root surface demineralization did not significantly alter the orientation, number and attachment of cells to the root co-cultures. The results also demonstrated that cementum and bone matrix appear to behave differently in culture, as seen by their distinct action on the morphological profile of the attached cells and the extracellular matrix deposited by these cells. These results demonstrate that although cementum matrix appears to stimulate the production of cementum-like tissue, this action is not confined to cementum matrix alone, since a similar material was also deposited on dentine and bone surfaces. Thus, these results do not support a specific action of cementum matrix on the modulation of the cementoblast phenotype. The use of co-cultures of neonatal rat calvaria cells with root slices represents a promising model of cementogenesis in vitro; however, studies should be undertaken towards the identification of markers to distinguish between cementoblast and osteoblast phenotypes in order to further validate this model.

An immunohistochemical investigation of the expression of parathyroid hormone receptors in rat cementoblasts.

Cementoblasts share many of the features of the osteoblast phenotype. To investigate their expression of cell surface receptors for parathyroid hormone (PTH) (i) unlabelled PTH was bound to tissue sections and subsequently detected with anti-PTH monoclonal antibodies; and (ii) digoxigenin (DIG)-labelled PTH was applied to the sections and the bound hormone detected with anti-DIG antibodies. The use of non-radioactive DIG-labelled PTH represents a novel approach for the immunodetection of PTH receptors in situ. The expression of PTH binding sites by cementoblasts of cellular, but not acellular, cementum was demonstrated. The immunoreactivity was weaker than that seen in osteoblasts, and mainly confined to cementoblasts of fully formed roots. These results suggest that cementoblasts of functional erupted teeth may be responsive to PTH stimulation and further support the idea that cementoblasts and osteoblasts share a similar phenotype.

The routine use of nasal topic vasoconstrictor for computerized tomography of nasal & paranasal cavities

The use of a long lasting nasal topic vasoconstrictor (NTVC) 15 minutes before CT-scans of nasal & paranasal cavities (N&PC) would be higbly advisable in order to avoid that normal or pathological transitory engorgement of the nasal mucosa can be interpreted as permanent or semipermanent changes in it, or toavoid that such transitory changes could obliterate the vision or importantanatomic or pathologic details, mostly in the middle meatus - a "K" area for interpretation of anterior sinuses inflamatory diseases. From a group of 10 patients who had CT-scans taken before and after the use of NTVC two cases ilustrates it quite well. The presence of swollen tissues not retracted by NTVC would indicate their permanent or semipermanent change. In evaluating nasal lumen patency, CT-scans after the use of NTVC - coronal or semicoronal sectionstaken for studying N&PC - can provide interesting and realistic correlations with rhinomanometric data from noses also decongested. The purpose of thisshort communication was to reiterate the advantage of NTVC use in N&PC CT-scans

Immunocytochemical investigation of the rat cementoblast phenotype.

Recent studies have suggested that cementoblasts may be derived from osteoblast progenitor cells, although the cementoblast phenotype has not been extensively characterized. This immunocytochemical study was carried out to investigate the expression by rat cementoblasts of a number of proteins which are characteristic of the osteoblast phenotype. Paraffin sections from developing rat tooth germs and from fully formed adult rat teeth with surrounding tissues, were incubated with antibodies to type I & III collagen, osteocalcin, transforming growth factor beta (TGE beta), and insulin-like growth factor 1 (IGF1). Frozen sections and unfixed resin-embedded sections were stained for alkaline phosphatase activity. Cementum and bone matrix were strongly positive for type I collagen, although there was only weak staining for type III collagen. Cementum was also positive for osteocalcin, which was particularly strong in the matrix of acellular cementum. Most osteoblasts and cementoblasts of the cellular cementum showed intense staining for TGF beta and IGF1, although some cementocytes and osteocytes were negatively stained. The osteoblast- specific anti-E11 mAb reacted strongly with cementoblasts and newly formed cementocytes in the cellular cementum. Cells associated with acellular cementum did not express TGF beta, IGF1 or stain positively with anti-E11 antibody at any time during root development. Cementoblasts were weakly or negatively stained for alkaline phosphatase in contrast to the osteoblasts examined, which may reflect the low level of synthetic activity in cementoblasts. These results demonstrate that osteoblasts and cementoblasts of cellular cementum share many phenotypic characteristics, and also suggest that there may be phenotypic differences between cementoblasts associated with cellular and acellular cementum.

Histochemical studies of acid and alkaline phosphatases in rat tooth germs with undecalcified resin-embedded specimens.

A novel technique for the histochemical demonstration of acid phosphatase (AcPase) and alkaline phosphatase (AkPase) in hard tissues has been proposed. Fresh, unfixed, undecalcified samples of rat tooth germs and surrounding structures were embedded in LR Gold resin at -20 degrees C. Sections of 2 microns were taken and subsequently processed for enzyme histochemistry. AkPase reaction product appeared as strong linear staining outlining cell boundaries and was present in the enamel organ, dental pulp, and osteoblast cells. Tartrate-resistant AcPase staining was seen exclusively in the osteoclasts of developing alveolar bone. Our results demonstrated that the use of unfixed, undecalcified LR Gold resin-embedded specimens for histochemistry is a novel technique which may be of value for certain studies when decalcification of specimens is undesirable. The technique appears to give good preservation of enzyme activity combined with the ability to prepare sections with excellent morphological detail.

[The heart transplant. The initial experience of the Instituto do Coração de Pernambuco]. / Transplante de coração. Experiência inicial no Instituto do Coração de Pernambuco.

PURPOSE: To describe the initial experience of a heart transplant program in Recife, Pernambuco. METHODS: Six patients in the final stage of heart failure were submitted to heart transplant. There were 4 male and 2 female patients, ranging in age from 15 to 61 years (mean, 43.8). Four had coronary heart disease and two dilated cardiomyopathy. The conventional operative technique of orthotopic heart transplant was used. All patients received a triple drug immunosuppressive therapy. RESULTS: There was one death due to acute rejection on the 28th postoperative day. The 5 survivors are in functional class I in a mean follow-up period of 113 days. CONCLUSION: The initial experience of a heart transplant program in Recife, Pernambuco, suggests that good long term results could be expected.

Ultrastructural visualisation of proteoglycans in early unmineralised dentine of rat tooth germs stained with cuprolinic blue.

The ultrastructural distribution and localisation of proteoglycans (PGs) of early developing rat dentine were examined using cuprolinic blue in a critical electrolyte concentration procedure. Results show that the cuprolinic blue method produces images of higher morphological quality than other cationic dyes. PGs appeared as ribbon-like electron-opaque precipitates of various sizes, ranging between 1.4 and 0.2 microns in length, distributed throughout the matrix and in close association with well preserved matrix vesicles and collagen fibrils. Matrix vesicles revealed tightly packed PG filaments which appeared to be attached to their membrane. It is possible that the close association of PG filaments with matrix vesicles and collagen indicates that PGs are related to the process of mineralisation of dentine.