Myelin basic protein binds GTP at a single site in the N-terminus

Myelin basic protein from normal human brain was ADP-ribosylated with Cholera toxin, but not with Pertussis toxin. It bound azido-GTP at a single site in the N-terminal tetrapeptide at the Gln residue. The binding was considerably reduced when GppNHp was present during azido-GTP binding and totally inhibited when GTP gamma S was present. The relevance of this specific binding is not understood at this time.

Tumour infiltrating lymphocytes in nasopharyngeal carcinoma

Tumour infiltrating lymphocytes were studied in 28 cases of undifferentiated carcinoma using a panel of monoclonal antibodies. For the T subsets we used OKT4 (helper/inducer), 8 (suppressor/cytotoxic), 11 (pan T), 9 (transferrin receptor) and Dako T6. For the B cells we used polyclonals IgM, D, G and A. Others were HNK-1 (natural-killer cells), THB-5 and W6/32 (HLA-ABC) and HLA-DR. Most of the lymphocytes were T cells and in 26 of 28 biopsies there were more T8 than T4 cells which could be seen around and within the tumour masses. There was also an increase in HNK and T6 cells. Tumour cells were positive for both W6/32 and HLA-DR. Occasional THB-5 positive cell could be seen within tumour masses. All tumour cells stained strongly with keratin and cytokeratin.

Effusions in the knee in elderly patients who were operated on for fracture of the hip

The incidence of an effusion in the knee in 155 consecutive elderly patients who had been operated on for a proximal femoral fracture was studied. The preoperative incidence had been 7.7 per cent in the ipsilateral knee and 1.3 per cent in the contralateral knee. Postoperatively, fifty patients (32.3 per cent) had an effusion on the ipsilateral side. In seven of them, the effusion had been present before the operation. All of the effusions subsided completely within three weeks after the operation. Results of the laboratory analysis of a specimen of the effused material from eight patients who were chosen at random showed non-inflammatory fluid. Probably the effusions were traumatic in origin, and it is likely that they were a response to stresses that had been incurred during the operation or at the time of fracture.

Treatment of unstable intertrochanteric fractures with Sarmiento valgus osteotomy and acrylic cement augmentation

Seventy unstable intertrochanteric fractures (Kyle III) were treated by Sarmiento valgus osteotomy, fixation with a sliding hip-screw and plate, and augmentation of the posteromedial upper femoral defect with acrylic cement. Immediate full weight bearing walking was started after the operation. Forty-two patients were followed up for more than 1 year (average 21.4 months). Excellent or good results were obtained in 71.4 per cent. However, there was mechanical failure in which the hip screw cut out of the femoral head superolaterally in 8.6 per cent. Comparison was made between the results of the present technique and our previously reported technique which consisted of Dimon-Hughston medial displacement osteotomy, fixation with sliding hip screw and acrylic cement augmentation to the upper posteromedial femoral defect. It was found that the result of the latter technique is slightly better, probably because of the more rigid reduction.

Reconstruction of the lateral tibial condyle by a pedicled vascularized fibular graft after en bloc resection of giant cell tumour

Two patients with giant cell tumour of the lateral tibial condyle underwent en bloc resection and reconstruction by pedicled vascularized fibular graft. Both had good functional results and rapid solid bony union. This procedure preserved the lateral stabilizing structures of the knee, allowed relatively early mobilization and provided some cartilagionous surface for articulation with the lateral femoral condyle. The procedure was technically simple compared with homograft reconstruction, prosthetic replacement or free vascularized bone grafts, and could be performed in less sophisticated centres. The operation also provided additional bone stock for subsequent fusion if necessary.

Bond strength of cements to nickel-chromium and silver-palladium alloys

The bonding of zinc phosphate, polycarboxylate, and reinforced ZOE cements to nickel-chromium and silver-palladium alloys was measured by cementing flat surfaces of the metals together. Polycarboxylate cement produced higher bond strengths than the other two cements to both metals. Polycarboxylate cement bonded better to nickel-chromium alloys than to a silver-palladium alloy. Zinc phosphate and reinforced ZOE cements had similar bond strengths except for Biobond, to which zinc phosphate cement provided higher bond strength. Polycarboxylate cement failed cohesively to both types of metals, and zinc phosphate and reinforced ZOE cements failed adhesively.

Build-up and repair of light-cured composites: bond strength

Interfacial bond strengths of light-activated composites were measured as a function of age using a transverse strength test. Bond strength between layers decreased with the age of the initial layer and reflected the setting curves of the composites. The highly-filled composites exhibited the greatest bond strengths. Uncut surfaces provided a better substrate for bonding than did ground surfaces. Use of a bonding agent on both uncut and ground surfaces improved bond strengths. Mean repair strengths of light-activated composites were similar to those of self-curing composites. Composites with ground surfaces aged for one wk had mean repair strengths 27% of the cohesive strength without bonding agent and 48% with bonding agent.

Variations in (Ca2+ + Mg2+)-ATPase, its inhibitor protein and calmodulin of density (age) separated rabbit erythrocytes

Density (age) separated rabbit erythrocytes were examined for differences in the activities of calmodulin and the protein inhibitor of membrane (Ca2+ + Mg2+)-ATPase (Lee, K.S. and Au, K.S. (1983) Biochim. Biophys. Acta 742, 54-62) as well as response of the ATPase towards these protein modulators. It was found that activities of the cytosol protein-bound and free inhibitor as well as membrane-bound inhibitor were higher in top (young) cells as compared to bottom (old) cells. Though the activity of the divalent cation associated membrane calmodulin pool was also higher in young cells, calmodulin activity in the erythrosol remained constant in cells from both age groups. The pool of membrane-associated inhibitor was shown to have greater influence on the ATPase than the membrane-associated calmodulin pool. The influence was more pronounced with inhibitor derived from old than from young cell membranes. Response of the young cell ATPase towards the protein inhibitor was better than the old cell enzyme at low inhibitor concentration. At higher inhibitor concentration, however, response of the ATPase from both cell types was similar.

Correlation between strength of bonding to enamel and mechanical properties of dental composites

The strength of bonding of dental composites to enamel was measured in shear. The compressive strength, proportional limit, elastic modulus, and tensile strength of the composites were measured for correlation with the bond strength. Conventional and microfilled composites with a range of filler concentrations were studied. The densities of the composites and their fillers and the concentrations of the fillers were determined. The mechanical properties that were most highly correlated with bond strength to enamel were proportional limit and elastic modulus. Tensile strength and filler concentration had lower correlation coefficients, and compressive strength was not correlated with bond strength. Using unfilled resins as bonding agents between the composites and enamel resulted in increased bond strength with half of the composites.

Bond strength of cements to crown bases

Amalgam crown bases provided more bond strength to cements than composite resin and cast gold. Modified zinc oxide-eugenol and polycarboxylate cements served better with composite resin bases. Modified zinc oxide-eugenol cement bonded to cast gold better than polycarboxylate and zinc phosphate cements. Polycarboxylate cement bonded to amalgam better than modified zinc oxide-eugenol and zinc phosphate cements. Amalgam was the material of choice for a crown base.

Staining calcified dental tissues with food

The discoloration of enamel caused by food substances was found to be superficial and for dentin and cementum ingressive. Discoloration of cementum exceeded that of dentin, and dentin stained more than enamel. Coffee and soy sauce stained the calcified dental tissues more than the cola beverage and tea. The longer the staining time, the deeper was the discoloration.

Auxiliary retention for complete crowns provided by cement keys

1. Cement keys were an effective means of increasing the retention of complete cast gold crowns to preparations in extracted teeth. 2. Single grooves placed in either the dentin or in the crown alone were not effective in increasing retention in 30-degree crowns. In 7-degree crowns, a single groove in the crown gave better retention than a single groove in the dentin. 3. Crowns with a 7-degree taper had greater retentive strengths than 30-degree crowns treated identically. The retentive strength of 7-degree crowns with cement keys approached the tensile strength of zinc phosphate cement.

Marginal leakage of compacted gold, composite resin, and high-copper amalgam restorations

Amalgam and compacted gold were found to have the least marginal leakage in Class V cavities. Composite resin with acid etching performed at an acceptable level. Without acid etching the marginal seal was unsatisfactory. The following conclusions can be drawn: 1. High-copper amalgam and compacted gold are the materials of choice for Class V restorations when esthetics are not of primary concern. 2. If composite resins are to be used, they should be placed with an acid-etch technique.

Auxiliary retention for intracoronal cast gold restorations

The retention of Class V inlays cemented to cavities in extracted teeth was significantly increased by placing opposing retentive grooves in the inlays and cavity walls. The set cement formed a bridge between the two retentive grooves.

The ability of foods to stain two composite resins

In this bench study, coffee and soy sauce stained composite resin restorations to a significantly greater degree than did tea or cola beverage. Generally, the greatest degree of staining with all samples occurred during the first week of the study time. The stain penetration was superficial and was estimated to be 5 mu or less.

Effect of clinical finishing procedures on amalgam microstructure

Spherical amalgam specimens were burnished, burnished-polished, polished (wet), or polished (dry). The amalgams were sectioned normal to the prepared surface, elemental analyses were made at a series of depths from the surface with the electron microprobe and the phase fractions were calculated. Significant variations in phase distributions exist within 100 micrometers of the surface.

The cutting effectiveness of carbide fissure burs on teeth

The cutting effectiveness of the burs decreased with time. While the multivariate analysis of variance showed an overall difference among the three groups, these differences appeared to be due to the shape of the curves (the linear and quadratic components) rather than to their average location (the mean). Therefore there were no significant differences in cutting among the three types of burs tested. The SEM photomicrographs showed that there was no gross bur damage after the burs were used for cutting tooth structure. The cutting mechanism of a carbide bur on tooth structure needs further investigation.

Comparison of the retentive strength of two cast gold pin techniques

The retention contributed by the use of pins with gold castings can be substantially increased by the technique of placing a threaded pin in the dentin and making a casting with a threaded receptacle to fit the pin. The basis for the improvement is the greater retention of threaded pins to dentin compared to that of smooth, cemented pins that are part of the casting. The limitation on the retention achieved with the new technique is the cohesive strength of the cement. Zinc phosphate cement provided the highest retention, and EBA and polycarboxylate cements provided lower and similar retention when threaded pins were cemented to threaded receptacles.

Acid etch bonded cast orthodontic retainers

We have described a technique which involves the use of a cast orthodontic retaining appliance bonded by the acid etch technique and composite resin for semipermanent retention. The technique provides an alternative form of treatment which offers some unique advantages over previous retentive techniques.

Dentinal crazing and interpin distance

All three types of self-threading plus cause dentinal crazing. The frequency and degree of damage done to the dentin varies significantly between the three types of pins and depends upon the differences in the diameters of the drill and the pin. When two or more pins are placed in dentin, the potential for dentinal damage increases. Minikin pins (0.019-inch diameter) caused the least damage, in terms of both degree and frequency. The optimum and safe interpin distance using Minikin pins suggested by this study is 3 mm. Minim and Regular pins (0.023- and 0.031-inch diameters, respectively) caused more injury than Minikin pins. The Regular pins showed more damaging effects on dentin than Minim pins, both in terms of degree and frequency. On the basis of this study, the minimum interpin distance using Minim or Regular pins should be 5 mm. These minimum interpin distances are applicable only in situations where the dentin is not dehydrated or embrittled due to endodontic treatment. In teeth that have been endodontically treated, it would be advisable to use only the smallest self-threading pins and possibly increase the interpin distance if two or more pins are to be used.

The effect of finishing on the anodic polarization of high-copper amalgams

The influence of surface finishing procedures on the corrodibility of high-copper amalgams was measured. Anodic polarization curves were determined in Ringer's solution for amalgam samples made from a dispersion and a ternary alloy. Three types of finishes were compared: as carved, burnished, and polished. The polarization curves of the burnished and polished specimens were statistically similar (P greater than 0.05) at all potentials investigated. The carved samples exhibited higher corrosion currents at most of the potentials investigated.

The effect of surface finish on the anodic polarization of a conventional spherical amalgam

The corrosion of carved, burnished, polished, and burnished--polished samples of a conventional spherical amalgam was studied by anodic polarization in Ringer's solution. The effect of the variation of the mercury content from 40 to 60 wt% on the corrosion of burnished or polished samples was also investigated. It was found that burnished and burnished--polished samples corrode the least and carved samples the most. The current-density peak associated with gamma2 was of greater magnitude in polished specimens than in burnished specimens throughout the range of mercury concentrations investigated. It is hypothesized that lower porosity and more ready passivation of the surface due to a high amount of gamma2 are the reasons that burnished samples corroded less than polished samples in this anodic polarization test.