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Biomedical subjects

R Giordano

Publications and source records attributed to R Giordano.

At least 181 records · Page 10Linked to original sources

[Myocellular necrosis by cathecolamines in pheochromocytoma (author's transl)].

A case of myocellular necrosis by cathecholamines in a patient presenting pheocromocytoma is reported. Death was due to cerbral apoplexy. The histological findings are quite specific and show myofibrillar degeneration with substitution of the normal striation by coarse sarcomeric transversal bands. The possible role of necrosis by catecholamines in sudden deaths and non-coronary myocardiosclerosis is emphasized.

Adrenal Glands↗

Malignant transformation of BHK21 clone 13 cells in vitro by nitrosamines--a conditional state.

All the BHK(21) Clone 13 cells transformed by dimethylnitrosamine or nitrosomethylurea, and a single "spontaneously" transformed clone obtained in our laboratory, exhibit a conditional state of the transformed phenotype. Upon growth at 38.5 degrees , they have a transformed phenotype (clonal morphology and the ability to plate in soft agar); when grown at 32 degrees , their phenotype is normal. The conditional state of these cells, however, does not extend to their growth characteristics; their plating efficiency at the two temperatures in liquid medium is similar. Conversion from the normal to the transformed phenotype and the reverse is possible by temperature shifts. A working hypothesis is proposed suggesting that this phenomenon may be caused by a temperature-sensitive mutation of a cellular gene whose product is responsible for maintaining the normal phenotype. The high temperature would then affect either the synthesis or the function of the protein carrying the temperature-sensitive alteration and, as a consequence, the transformed phenotype would be expressed.

Animals↗

A comparison of all-ceramic restorative systems: Part 2.

Overall, any of these systems can provide well-fitting, natural looking restorations as long as care is taken during the preparation and fabrication procedures. A key to successful use of all-ceramic materials is proper selection based on the clinical conditions involved in specific restorative procedures (see table). All systems have limitations on their use and when we try to stretch those limits, success rates may fall drastically. High stress areas should shift selection to high strength, clinically documented materials. Low stress areas requiring high translucency may be restored successfully using the lower strength castable glasses. Intermediate areas may shift selection to higher strength yet still translucent materials such as In-Ceram Spinell or Empress 2. Posterior regions might best be addressed with the use of In-Ceram Alumina or Procera. The case of posterior bridges would lock the selection into In-Ceram Zirconia. Finally, it is important for each of us to continually educate ourselves and to examine the evidence in order to make an informed decision and maximize clinical success.

Aluminum Oxide↗

Fiber reinforced composite resin systems.

The Targis/Vectris and Sculpture/FibreKor systems were devised to create a translucent maximally reinforced resin framework for fabrication of crowns, bridges, inlays, and onlays. These materials are esthetic, have translucency similar to castable glass-ceramics such as OPC and Empress, and have fits that are reported to be acceptable in clinical and laboratory trials. These restorations rely on proper bonding to the remaining tooth structure; therefore, careful attention to detail must be paid to this part of the procedure. Cementation procedures should involve silane treatment of the cleaned abraded internal restoration surface, application of bonding agent to the restoration as well as the etched/primed tooth, and finally use of a composite resin. Each manufacturer has a recommended system which has been tested for success with its resin system. These fiber reinforced resins are somewhat different than classical composites, so not all cementation systems will necessarily work with them. Polishing of the restoration can be accomplished using diamond or alumina impregnated rubber wheels followed by diamond paste. The glass fibers can pose a health risk. They are small enough to be inhaled and deposited in the lungs, resulting in a silicosis-type problem. Therefore, if fibers are exposed and ground on, it is extremely important to wear a mask. Also, the fibers can be a skin irritant, so gloves also should be worn. If the fibers become exposed intraorally, they can cause gingival inflammation and may attract plaque. The fibers should be covered with additional composite resin. If this cannot be accomplished, the restoration should be replaced. The bulk of these restorations are formed using a particulate filled resin, similar in structure to conventional composite resins. Therefore, concerns as to wear resistance, color stability, excessive expansion/contraction, and sensitivity remain until these materials are proven in long-term clinical trials. They do hold the promise of minimizing tooth reduction and may be particularly useful in preserving sound tooth structure. Although not the primary intended use, an excellent application is long-term temporization, such as for patients requiring full mouth rehabilitation. The belleGlass/Connect, Ribbond, and GlasSpan materials rely on nonimpregnated polyethylene fibers which have mechanical properties inferior to Vectris and FibreKor. These fibers may be used to greater success as splinting materials, in provisional restorations, and in repair of complete and partial removable dentures.

Composite Resins↗

[Current role of traditional endoscopy and prospects for virtual colonoscopy in the management of colorectal neoplastic lesions].

The Authors, reviewing their surgical experience with colo-rectal cancer in the last 13 years, conclude that, in the management of this condition, the routine use of traditional endoscopy will continue to have a crucial role in terms of prevention, cure and/or survival. It is possible that in the future present limits of endoscopic techniques will be seperated by routine use of endoscopic ultrasounds and virtual colonoscopy.

Adult↗

[Current role of endoscopic ultrasonography in the treatment of colorectal neoplastic lesions].

The Authors examined the value of endoscopic ultrasounds in the tmanagement of colo-rectal lesions, particularly neoplastic ones, on the basis of their surgical experience, concluding that to date such technique cannot substitute traditional endoscopy, but surely can be a valid complementary tool for imaging diagnostics, expecially to study wall tumoral infiltration or extra-parietal relapses.

Colonoscopy↗

Issues in handling impression materials.

Implant restorations require extreme accuracy since the implants are rigidly fixed. Although impression materials can be highly accurate, small inaccuracies are acceptable because the periodontal ligament allows for tooth movement. This luxury is not available with implants. A problem is the rotation of direct impression copings and distortion of interabutment positions in the master cast. Wee investigated the amount of torque required to displace a coping in eight impression material groups and the positional accuracy of the materials. The initial examination of torque narrowed the acceptable materials to a medium viscosity polyether, a high viscosity addition silicone, and a medium viscosity polysulfide-condensation silicones were eliminated. The results showed that the polyether and addition silicone produced casts with minimal distortion. Finally, it always is prudent to read the manufacturer's recommendations for use of impression materials. Catalyst-to-base ratios vary, as do working and setting times, depending on exact compositions. Impression materials also have various degrees of compatibility with stone, particularly the hydrocolloids, and it is advisable to use the recommended stone. Adhesives should be applied at least 15 minutes prior to loading the impression material. If at all possible, use of a rigid tray is recommended and impressions should be poured in the dental office; this minimizes the error produced at the beginning of the fabrication process. Elimination of errors early in fabrication of a prosthesis help prevent their magnification and result in a better-fitting restoration, requiring minimal adjustment in the end.

Colloids↗

Fracture surface analysis of dental ceramics: clinically failed restorations.

Fractography was used to study all-ceramic restorations that had failed clinically. Some basic tenets of fracture mechanics and fractography are reviewed and related to the examination of clinically failed all-ceramic restorations. Dicor and Cerestore restorations that had failed either at trial placement or 17 to 36 months postcementation were evaluated. Failed Dicor restorations were studied to determine the origin of failure and calculate the intraoral stress at failure. Descriptive information regarding crack origin and crack path were obtained from failed restorations constructed of first-generation Cerestore. A majority of the crowns apparently failed from the internal surface, indicating this as the highest tensile surface and/or the location of the largest flaws. Flaws were identified as being related to fabrication or inherent in the ceramic microstructure.

Aluminum Oxide↗