Blocking antibodies and T cell subsets in long-term survivors of renal allografts.

Fc-receptor blocking antibodies as well as T cell subsets were studied in a group of 12 long-term survivors of renal allografts. The absolute number of T suppressor cells was similar to that found in a control group, but there was a significant decrease in the total number of T helper lymphocytes and a decreased helper/suppressor ratio. Sera from all patients tested showed inhibitory activity in the erythrocyte antibody model against leukemic B lymphocytes, demonstrating the presence of Fc-receptor blocking antibodies. Also inhibited was the ability of normal human lymphocytes to form E rosettes and to induce a local xenogeneic graft-versus-host reaction. These findings indicate that the Fc blocking antibodies are beneficial to the patient, possibly by abrogating the cellular and humoral immune mechanism that is detrimental to the kidney allograft.

Immediate implantation after extraction of a horizontally fractured maxillary lateral incisor.

When indicated, osseointegrated implant prosthetics may be placed immediately following atraumatic tooth extraction. This article describes the delicate and precise surgical and prosthetic disciplines for an immediate extraction and implant case.

[Hydroxyapatite coated dental implants. Biological criteria and prosthetic possibilities]. / Implants dentaires recouverts d'une couche d'hydroxyapatite. Critères biologiques et possibilites prothétiques.

Incorporating contemporary implant research and the most advanced principals of biomaterials and bioengineering puts HA-coated implant system into clinical practice. This system utilizes a streamline precision two-stage procedure similar to the swedish method and other osseointegrated systems to ensure complete fixation and an unloaded healing phase prior to the functional use of implants. The surgical concept has been theoretically improved upon by enhancing the titanium cylinders with a HA coating of 50 to 65 microns to the body. The advantages of HA have been extensively discussed. Research has shown that a biochemical reaction occurs between HA and bone and the interface between bone and ceramic is stronger than either the ceramic or bone alone. Bone adapts well to all biocompatible metals and bone will "chemically" bond to HA. An activated sintering process has been developed that enables HA to be chemically bound to the titanium cylinder using a modification of the plasma flame spray technology. This HA coating has been developed to meet the most rigorous biomechanical requirements for bonding in high stress applications of orthopedics as well as intraoral use. Biointegration is defined as "mechanochemical" clinically significant interface that predictably develops between vital load bearing bone and a bioactive calcium-phosphate ceramic metal such as HA. The design and planning of the HA-coated metal system also provides a variety of restorative choices and have been extensively discussed in this article. Clinical reports appear excellent, and the current implant system is into its fifth year of clinical use. The use of HA-coated implants has very well satisfied restorative needs as well as following sound biologic principle.