The murine anti-human common gamma chain monoclonal antibody CP.B8 blocks the second step in the formation of the intermediate affinity IL-2 receptor.

A murine monoclonal antibody, CP.B8, specific for the extracellular portion of the human common gamma (gammac) chain, and its Fab fragment are shown to block the binding of IL-2 to COS-7 cells transfected with the cDNA for the full-length IL-2 receptor beta (IL-2Rbeta) and gammac chains, components which together comprise the intermediate affinity IL-2 receptor (IL-2R) expressed on the surface of resting T cells, NK cells, and on certain intestinal epithelial cells. To investigate the mechanism of this inhibition, the extracellular portions of the IL-2Rbeta and gammac chains were expressed and purified, and their interactions with each other and with IL-2 were studied by gel filtration and by surface plasmon resonance (SPR). By gel filtration, a stable ternary complex was formed by association of the three proteins, while no stable binary complexes were detected between any two of the three proteins. By SPR analysis, IL-2 was shown to associate rapidly with IL-2Rbeta, forming a binary complex with an equilibrium dissociation constant (Kd) of 800 nM, which permitted subsequent association of the gammac chain. Dissociation of the IL-2/IL-2Rbeta/gammac chain complex was significantly slower than dissociation of the IL-2/IL-2Rbeta complex. Using these model systems, we tested the ability of mAb CP.B8 to inhibit the association of the gammac chain with IL-2 and IL-2Rbeta. By gel filtration, mAb CP.B8 formed a stable complex with the gammac chain, preventing its association with IL-2 and IL-2Rbeta. MAb CP.B8 was also capable of dissociating the gammac chain already complexed with IL-2 and IL-2Rbeta. SPR analysis confirmed these findings and showed, in addition, that the Fab fragment of CP.B8 was also capable of inhibiting the association of the gammac chain with the IL-2/IL-2Rbeta complex. We conclude that mAb CP.B8 blocks the second step in the formation of the intermediate affinity IL-2R on the surface of transfected COS-7 cells by binding at or close to a region on the gammac chain that is involved in contact with IL-2 and/or IL-2Rbeta.

Mechanical considerations for the implant tooth-supported fixed partial denture.

The implant tooth-supported fixed partial denture presents a biomechanical design problem, because the implant is rigidly fixed within the alveolus, and the tooth is surrounded by a periodontal ligament that allows movement. Nonrigid fixed partial denture designs are advocated by some dentists as a method of compensating for this differential movement. Rigid fixed partial denture designs, however, are advocated by many clinicians. Studies have failed to show the advantage of one design over the other. This study developed an in vitro method for testing such prosthesis designs and measured movement of a natural tooth abutment during simulated function. The movement of the natural tooth abutment was not found to change substantially with the fixed partial denture designs tested.

Comparison of screw loosening, rotation, and deflection among three implant designs.

A common problem associated with single tooth implant restorations is abutment screw loosening. Manufacturers of implants have attempted to overcome this problem by incorporating antirotational design characteristics into their systems. Micromovement and torque levels required to loosen abutment screws for straight and angled antirotational screw-retained abutment/implant combinations from three different manufacturers were examined in this in vitro investigation. A custom-built machine was used and each sample was subjected to compressive horizontal reciprocal movements over a 25-degree incline for a simulated 1-month period. Data were generated that showed movements of the crown/abutment complex during force application. The amount of torque necessary to loosen the abutment screws before and after testing was also recorded and compared for each system. The results indicated no significant differences (p < 0.05) among all the straight and angled abutments for the variables studied.

Plasma prolactin concentrations and pregnancy-induced hypertension.

Human prolactin (PRL) has been related to various pathologic disorders known to be associated with osmoregulation and hypertension. In this study, we compared changes in plasma PRL concentrations in normal pregnant patients to those in patients with severe pregnancy-induced hypertension (PIH). Comparison of plasma PRL concentrations collected antepartum, at delivery, and 48 hours postpartum failed to distinguish women with PIH from those without. Only women with PIH, however, showed a significant rise in systemic PRL concentrations between admission to the study and delivery. Antepartum abnormalities in plasma PRL concentrations associated with PIH may not have been detected because of diurnal variations in PRL secretion.

Treatment of premature rupture of the membranes.

Few topics in obstetrics are debated more widely than the treatment of premature rupture of the fetal membranes (PROM). Over a two-year period, a retrospective analysis of 422 patients with that diagnosis revealed 86 mother-infant pairs at less than 37 weeks of gestation acceptable for review as it pertained to expectant or conservative management. The gestational age in these patients ranged from 26 to 36 weeks, with a mean of 31.9. Using the conservative management approach, 12% of the patients developed amnionitis during the antepartum period, and febrile morbidity was noted postpartum in eight patients. The neonatal outcome revealed a 14% incidence of respiratory distress syndrome (RDS). There were 18 infants with suspected sepsis, but of the 6 cases of proven infection, only 1 was related to amnionitis. Ten of the 12 infants contracting RDS were males, reflecting a reversal of the sex ratio found in those who did not develop RDS. The sex difference in the offspring was found to favor females with respect to RDS, even greater than 48 hours after rupture of the membranes. These data demonstrate that with the use of expectant management in patients with PROM at 26-36 weeks of gestation, there was no dramatic increase in maternal or neonatal infections.