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Biomedical subjects

R A Freitas

Publications and source records attributed to R A Freitas.

11 recordsLinked to original sources
PubMed2004

Immunohistochemical assessment of extracellular matrix components in syndrome and non-syndrome odontogenic keratocysts.

OBJECTIVE: Investigate the immunohistochemical distribution of fibronectin, tenascin, laminin and collagen IV in syndrome (SOKC) and non-syndrome odontogenic keratocysts (NSOKC). MATERIALS AND METHODS: Ten cases of SOKC and five of NSOKC were selected and streptoavidin-biotin technique was applied. The specimens were analyzed taking into account the following evaluation parameters: presence, continuity and thickness in the basement membrane and intensity, distribution and association with inflammatory cells in the cyst wall. RESULTS: Differences could be detected regarding tenascin, fibronectin and collagen IV between the SOKC and NSOKC. Tenascin was present in all cases along the basement membrane in SOKC and in five cases of NSOKC predominated negative areas. Furthermore, tenascin distribution was focal in the cyst wall in SOKC whereas in NSOKC it was diffuse. Concerning fibronectin, it was detected as a discontinuous band when present in SOCK and as a continuous band in NSOKC. Collagen IV was not present in the majority of the cases in SOKC. Negative areas for laminin predominated in the basement membrane in both groups. CONCLUSIONS: These findings show differences between the immunohistochemical expression of tenascin, fibronectin and collagen IV which might indicate a more aggressive biological behavior of SOKC as compared with NSOKC.

Adolescent↗
PubMed2002

The future of nanofabrication and molecular scale devices in nanomedicine.

Nanotechnology is engineering and manufacturing at the molecular scale, and the application of nanotechnology to medicine is called nanomedicine. Nanomedicine subsumes three mutually overlapping and progressively more powerful molecular technologies. First, nanoscale-structured materials and devices that can be fabricated today hold great promise for advanced diagnostics and biosensors, targeted drug delivery and smart drugs, and immunoisolation therapies. Second, biotechnology offers the benefits of molecular medicine via genomics, proteomics, and artificial engineered microbes. Third, in the longer term, molecular machine systems and medical nanorobots will allow instant pathogen diagnosis and extermination, chromosome replacement and individual cell surgery in vivo, and the efficient augmentation and improvement of natural physiological function. Current research is exploring the fabrication of designed nanostructures, nanoactuators and nanomotors, microscopic energy sources, and nanocomputers at the molecular scale, along with the means to assemble them into larger systems, economically and in great numbers.

Biomedical Technology↗
PubMed2000

Nanodentistry.

BACKGROUND: Nanodentistry will make possible the maintenance of comprehensive oral health by involving the use of nanomaterials, biotechnology (including tissue engineering) and, ultimately, dental nanorobotics (nanomedicine). RESULTS: When the first micrometer-sized dental nanorobots can be constructed within 10 to 20 years, these devices will allow precisely controlled oral analgesia, dentition replacement therapy using biologically autologous whole replacement teeth manufactured during a single office visit, and rapid nanometer-scale precision restorative dentistry. CLINICAL IMPLICATIONS: New treatment opportunities may include dentition renaturalization, permanent hypersensitivity cure, complete orthodontic realignments during a single office visit, covalently bonded diamondized enamel and continuous oral health maintenance through the use of mechanical dentifrobots.

Dental Equipment↗
PubMed2000

Distribution of phlebotomine sand flies (Diptera: Psychodidae) in the state of Rio Grande do Norte, Brazil.

Visceral and cutaneous leishmaniasis are major endemic diseases in northeast Brazil. The objective of the current study was to determine the species and geographic distribution of potential sand fly vectors of Leishmania in the state of Rio Grande do Norte. Sand flies were captured using CDC light traps in 30 municipalities distributed throughout the 8 geographic zones of the state. Twelve Lutzomyia species were identified. Lutzomyia longipalpis Lutz & Neiva was the most prevalent and accounted for 85.59% of the sand fly captured. The remaining species were distributed as follows: L. evandroi Costa Lima & Antunes (10.83%), L. oswaldoi Mangabeira (0.99%), L. sallesi Galvão & Coutinho (0.58%), L. intermedia Lutz & Neiva (0.53%), L. lenti Mangabeira (0.53%), L. migonei França (0.49%), L. walkeri Newstead (0.24%), L. goiana Martins, Falcão & Silva (0.15%), L. samueli Deane (0.04%), and L. capixaba Dias, Falcão, Silva & Martins (0.03%), and L. peresi Mangabeira (0.01%). L. longipalpis, which is known to be a vector of Leishmania chagasi Cunha & Chagas (L. donovani chagasi), was captured in 93% of municipalities distributed across all geographical areas of the state and its distribution was independent of obvious climatic and topographic parameters. It was identified in all municipalities where human visceral leishmaniasis had been reported. In contrast, climate and topography appeared to be important for other Lutzomyia species. For example, L. intermedia and L. migonei, which are known to transmit Leishmania braziliensis Viana, were geographically restricted. They were captured in municipalities where cases of cutaneous and mucosal leishmaniasis had been reported. The widespread distribution of L. longipalpis, its adaptation to peridomicillary settings, and its ability to transmit L. (d.) chagasi suggest that a large number of persons may be at risk of acquiring visceral leishmaniasis in the state of Rio Grande do Norte, Brazil.

Animals↗
PubMed1998

Exploratory design in medical nanotechnology: a mechanical artificial red cell.

Molecular manufacturing promises precise control of matter at the atomic and molecular level, allowing the construction of micron-scale machines comprised of nanometer-scale components. Medical nanomachines will be among the earliest applications. The artificial red blood cell or "respirocyte" proposed here is a bloodborne spherical 1-micron diamondoid 1000-atm pressure vessel with active pumping powered by endogenous serum glucose, able to deliver 236 times more oxygen to the tissues per unit volume than natural red cells and to manage carbonic acidity. An onboard nanocomputer and numerous chemical and pressure sensors enable complex device behaviors remotely reprogrammable by the physician via externally applied acoustic signals.

Biocompatible Materials↗
PubMed1993

Argyrophilia in nucleolar organizer regions (AgNOR) in adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma of the salivary glands.

Nine cases of adenoid cystic carcinomas (ACC) and three cases of polymorphous low-grade adenocarcinomas (PLGA) of the salivary glands from the Surgical Oral Pathology Service of the University of São Paulo School of Dentistry were examined by means of the silver-staining nucleolar organizer regions (AgNOR) technique. Quantitative and dimensional analyses of NORs were carried out. Our findings suggest that solid and cribriform patterns of ACC have a higher cellular activity than that presented by tubular ACC and PLGA.

Adenocarcinoma↗
PubMedDate not supplied

A pilot study to control Lutzomyia umbratilis (Diptera:Psychodidae), the major vector of Leishmania braziliensis guyanensis, in a peri-urban rainforest of Manaus, Amazonas State, Brazil.

In the second half of 1980, 112 (or ca. 16%) of the inhabitants of the new settlement of São José, city of Manaus, contracted cutaneous leishmaniasis whilst clearing their properties of terra firme rainforest. With the aid of SUCAM, the authors carried out a pilot study to investigate the feasibility of reducing populations of Lutzomyia umbratilis, the local silvatic vector of Leishmania braziliensis guyanensis, by spraying insecticide on its favoured diurnal resting sites, the bases of the larger forest trees. Most manvector contact is at these resting sites and, therefore, it was encouraging to record a marked reduction of the tree-base populations of L. umbratilis for 21 days following just one application of D.D.T. emulsion in an area 200m square. Most of the treated trunks were not occupied by L. umbratilis for at least eleven months. Suggestions for extending the pilot study are made, and the need for collaboration with a clinical team is emphasized. Leishmania b. guyanensis is the aetiological agent of "pain bois", which is hyperendemic from French Guiana to central Amazônia. In the absence of proven vaccines or methods of vector control, some simple methods for limiting transmission of Le. b. guyanensis to man are listed.

Animals↗
PubMedDate not supplied

Epidemiological and nosological aspects of Leishmania naiffi Lainson & Shaw, 1989.

Leishmania naiffi was isolated from 10 out of 64 armadillos (Dasypus novemcinctus) examined in Amazonas, Pará and Rondônia States in the Brazilian Amazon Region. The isolates were obtained in culture from samples of liver (3), spleen (3), lymph nodes (2), skin (1) and blood (1) from the infected animals. Heavy infections with the same parasite were detected for the first time in Psychodopygus squamiventris, a common man-biting phlebotomine, in Amazonas and Pará. A new case of cutaneous leishmaniasis caused by L. naiffi is described from the Manaus area, making a total of three known cases of human infection by this parasite.

Adult↗
PubMedDate not supplied

Lutzomyia derelicta (Diptera: Psychodidae) a singular new phlebotomine sand fly from an Inselberg in Northeastern Amazonia.

Lutzomyia derelicta n. sp. is described from specimens collected in an isolated xeric habitat in the rainforest in the north of the State of Pará, Brazil. The new species lacks the posterior bulge in the dorsal wall of the cibarium characteristic of the New World genus Lutzomyia, and the armature of the male genitalia is of the pattern found elsewhere only in the Old World species of Sergentomyia. L. derelicta is phenetically intermediate between the known species of Lutzomyia and Sergentomyia, and cannot readily be placed in any existing subgenus or species group of either genus.

Animals↗