Comparison of stress transmission in the IMZ implant system with polyoxymethylene or titanium intramobile element: a finite element stress analysis.

Using the finite element method, this study modeled a 4.0 x 13.0-mm IMZ implant, restored with a cast gold crown, to examine the influence of the polyoxymethylene (POM) intramobile element (IME) on the transmission of vertical and oblique forces. Stress concentrations in the bone and in components of the implant system were much greater under a 30-degree load than under an equal vertical load. Stress transmission to bone occurred chiefly in the crestal region, and these stresses were not reduced when the IME was modeled in POM rather than in titanium. Maximum stress concentrations occurred in the fastening screw.     

Midazolam sedation for outpatient fibreoptic endoscopy: evaluation of alfentanil supplementation.

Alfentanil, a short-acting opioid, was used as an adjuvant to midazolam for sedation of 30 outpatients undergoing upper gastrointestinal endoscopy. The operating conditions and recovery times were compared with those of a similar group of 30 patients sedated with midazolam only. The use of alfentanil resulted in improved operating conditions and a more rapid recovery. Patient acceptance was high.     

Effects of the herbicides hexazinone and triclopyr ester on aquatic insects.

Experiments were conducted to measure acute lethal response of aquatic insects to hexazinone (Velpar L) and triclopyr ester (Garlon 4) in flow-through laboratory bioassays, and to determine lethal and behavioral effects of these herbicides on insects in outdoor stream channels. No significant mortality (chi 2 P greater than 0.05) occurred in 13 test species exposed to hexazinone in laboratory flow-through bioassays (1-hr exposure, 48-hr observation) at the maximum test concentration of 80 mg/liter. The survival of insects exposed to 80 mg/liter hexazinone in outdoor stream channels was likewise unaffected. Significant drift (chi 2 P less than 0.001) of Isonychia sp. occurred during a hexazinone treatment of the stream channels, but only at the maximum concentration of 80 mg/liter, and survival of the displaced Isonychia sp. was not affected. In flow-through bioassays with triclopyr ester, 10 of 12 test species showed no significant mortality at concentrations greater than 80 mg/liter. Survival of Isogenoides sp. and Dolophilodes distinctus was significantly affected at less than 80 mg/liter. Lethal concentrations were estimated by probit analysis of concentration-response data (1-hr exposure, 48-hr observation) for Simulium sp. (LC50 = 303 mg/liter), Isogenoides sp. (LC50 = 61.7 mg/liter), and D. distinctus (LC50 = 0.6 mg/liter). Triclopyr ester applications to the stream channels resulted in significant drift and mortality of D. distinctus at 3.2 mg/liter (no effects at 0.32 mg/liter), Isogenoides sp. at 32 mg/liter, and Hydropsyche sp. and Epeorus vitrea at 320 mg/liter. The risk to aquatic insects of these herbicides used in forest vegetation management is discussed.     

Immunogenicity of four Haemophilus influenzae type b conjugate vaccines in 17- to 19-month-old children

OBJECTIVE: To compare the immunogenicity of four Haemophilus influenzae type b (Hib) conjugate vaccines in different populations of 17- to 19-month-old children in the United States. DESIGN: Four immunogenicity trials with sera were assayed in one laboratory. Trials 1 and 2 each compared one vaccine in two regions, and trials 3 and 4 were randomized comparisons of multiple vaccines within a region. SUBJECTS: A convenience sample of 313 healthy children recruited from pediatric practices in Minneapolis, Minn., Dallas and Houston, Tex., and Sellersville, Pa. MEASUREMENTS AND RESULTS: Children with prevaccination antibody greater than 0.15 microgram/ml showed higher antibody responses to vaccination than children with less than or equal to 0.15 microgram/ml (p less than 0.001). Among the former, there were no significant differences in antibody response to vaccination with the different conjugates within any of the trials. Among children with less than or equal to 0.15 microgram/ml of antibody before vaccination, there were no significant differences in the geometric mean antibody responses of children in trial 1 vaccinated with polyribosylribitol phosphate-diphtheria toxoid (PRP-D) in Dallas or in Minneapolis, or of children in trial 3 in Dallas randomly assigned to receive Hib oligosaccharide-CRM197 (HbOC) or PRP-D. In contrast, in trial 2, children given PRP-tetanus toxoid (PRP-T) in Pennsylvania had a significantly higher geometric mean antibody response than children given PRP-T in Houston (13.5 vs 3.0 micrograms/ml; p = 0.005). In trial 4 in Minneapolis, the geometric mean antibody response was highest in children randomly assigned to receive PRP-outer membrane protein (OMP) (9.3 micrograms/ml), followed by PRP-D (5.0 micrograms/ml) and HbOC (2.3 micrograms/ml) (PRP-OMP vs HbOC; p = 0.005). In all four trials, IgG1 responses predominated compared with IgG2 responses. CONCLUSIONS: All four conjugate vaccines are immunogenic in children 17 to 19 months of age. However, the magnitude of the anticapsular antibody response varied by vaccine type, the level of antibody in prevaccination sera, and geographic location.     

Evaluation of trophoblast HLA-G antigen with a specific monoclonal antibody

A monoclonal antibody to HLA-G has been generated by immunizing HLA-A2.1/human β²-microglobulin (β²m) double transgenic mice with murine L cells transfected with both human β²m and HLA-G. This monoclonal antibody, designated as G233, has been found not to cross-react with other HLA class I antigens when tested on numerous cell lines by flow cytometry. With immunohistology, all populations of extravillous trophoblast (cell columns, interstitial trophoblast, endovascular trophoblast, placental bed giant cells) were stained. An extensive range of adult and fetal tissues was also tested but none reacted with monoclonal antibody G233, including those previously reported to express HLA-G mRNA, indicating that the protein has a highly restricted distribution. Failure to detect HLA-G in the fetal thymus raises the question as to how T-cell tolerance to this antigen is induced. Immunoprecipitation of trophoblast surface proteins with monoclonal antibody G233 revealed a heavy chain of 39 kDa and a light chain of 12 kDa, indicating that HLA-G expressed on the surface of trophoblast is complexed with p2m. However, sequential immunoprecipitation with monoclonal antibody W6/32 followed by monoclonal antibody G233 continued to detect a residual band of 39 kDa, suggesting that trophoblast surface HLA-G may also occur as free heavy chains not associated with p2m. Immunoprecipitation followed by two dimensional gel electrophoresis showed that monoclonal antibody G233 recognizes several iso-forms of HLA-G from trophoblast similar to the characteristic spot array previously described for HLA-G. This monoclonal antibody G233 will be highly useful in future experiments to elucidate the function of HLA-G.     

Postnatal development of mouse alcohol dehydrogenases: agarose isoelectric focusing analyses of the liver, kidney, stomach and ocular isozymes

The postnatal development of alcohol dehydrogenase (ADH) isozymes was studied in liver, kidney, stomach and eye tissues of C57BL/6J inbred male mice using agarose isoelectric focusing and histochemical methods. Development profiles were tissue specific, with adult patterns being attained by 30 days in the liver and stomach, and by 42 days in the kidneys. Ocular ADH-C2 increased in activity at the end of the first week, corresponding to the time of eye opening in the neonate.     

In vitro study of the transfer of cytokine-inducing substances across selected high-flux hemodialysis membranes.

The in vitro transfer of cytokine-inducing substances (CIS) across cellulose triacetate and polyacrylonitrile hollow-fiber high-flux hemodialyzers was studied using culture filtrates of gram-negative bacteria isolated from hemodialysis center environments. With Enterobacter cloacae, no transfer of CIS was seen despite the potent cytokine inducibility and endotoxin content of the challenge solution. In contrast, interleukins 1 and 6 and tumor necrosis factor inducing substances did penetrate both dialyzer types challenged with Pseudomonas aeruginosa culture filtrates containing a high endotoxin content. Transfer was not seen, however, upon dilution of the challenge solution to lower, yet clinically very high levels of endotoxin. These results show that, in vitro, the transfer of CIS across high-flux membranes is critically dependent upon the quality and the quantity of the challenge material employed.