Failure of axially compressed frangible joints in cylindrical shells

A computer program for the analysis of stress, nonlinear collapse and bifurcation buckling of hybrid bodies of revolution (BOSOR6) is used for the prediction of failure of axially compressed cylinders containing frangible joints. Plasticity and moderately large deflections are included in the analytical models. The structure in the immediate neighborhoods of the frangible joint notches is modeled with use of eight-node solid isoparametric finite elements of revolution and the rest of the structure is modeled with use of computationally efficient thin shell elements.Theoretical predictions are compared to test results. Certain aspects of the test specimens and boundary conditions remain unknown, and parameters in the analytical models are established and varied in order to reveal what these test conditions must have been. For reasonable values of these parameters, theoretical and experimental joint failure loads agree to within 2%.     

Altered expression of Ly-49 receptors on NK cells developing in mixed allogeneic bone marrow chimeras

Ly-49 molecules are used by NK cells to distinguish 'self' from 'non-self', but the determinants of Ly-49 expression that allow this distinction to be made are not understood. The education of NK cells for self/non-self recognition was studied in murine mixed allogeneic bone marrow chimeras, in which NK cells are of both host and donor origin. Marked alterations in Ly-49 receptor expression were observed on both host and donor NK cells developing in BALB/c --> B6 mixed chimeras. Ly-49A and Ly-49G2 expression was lower on host B6 NK cells of mixed chimeras compared to non-transplanted B6 controls. Among donor BALB/c NK cells, Ly-49C expression levels were reduced, but the proportion of Ly-49C+ cells was increased, whereas Ly-49G2 expression was up-regulated compared to non-transplanted BALB/c controls. Thus, Ly-49 expression on donor and host NK cells developing post-bone marrow transplantation evolves toward the expression pattern of the host and donor strains respectively, due to the presence of the allogeneic MHC. In vitro functional NK cell assays showed that donor NK cells in mixed chimeras were not tolerant to host antigens and that host NK cells were not tolerant to the donor. Our data are consistent with a model in which MHC expression in the environment has a dominant down-regulating effect on the expression of Ly-49 molecules that recognize those MHC molecules, regardless of whether they are self or allogeneic. This down-regulation, combined with the limited repertoire of Ly-49 molecules, may not be sufficient to allow NK cells to be tolerant of MHC antigens of a fully MHC-mismatched allogenic strain.     

Allogeneic bone marrow transplantation for low-grade lymphoma

Advanced low-grade lymphomas are usually incurable with conventional-dose chemotherapy. It is uncertain whether cures are possible with high-dose therapy and bone marrow transplant from a human leukocyte antigen (HLA)-identical sibling. We sought to determine the outcome of HLA-identical sibling bone marrow transplants in advanced low-grade lymphoma in an observational study of 113 patients conducted at 50 centers participating in the International Bone Marrow Transplant Registry (IBMTR). The median patient age was 38 years (range, 15 to 61). Eighty percent had stage IV disease at the time of transplantation. The median number of prior chemotherapy regimens was two (range, 0 to 5). Thirty-eight percent had refractory disease and 29% a Karnofsky performance score (KPS) less than 80%. All patients underwent allogeneic bone marrow transplantation from a HLA-identical sibling donor. The conditioning regimen included total-body irradiation (TBI) in 82% of patients; cyclosporine was used for graft-versus-host disease prophylaxis in 74%. Survival, disease-free survival, recurrence rate, treatment-related mortality, and causes of death were determined. Three-year probabilities of recurrence, survival, and disease-free survival were 16% (95% confidence interval [CI], 9% to 27%), 49% (95% CI, 39% to 60%), and 49% (95% CI, 39% to 59%), respectively. Higher survival was associated with pretransplant KPS >/=90%, chemotherapy-sensitive disease, use of a TBI-containing conditioning regimen, and age less than 40 years. We conclude that high-dose therapy followed by transplantation from a HLA-identical sibling leads to prolonged survival in some patients with advanced low-grade lymphoma. Most mortality is treatment-related, and recurrences are rare.     

Trabeculectomy and postoperative ocular hypertension in secondary angle-closure glaucoma

I performed trabeculectomies to reduce the introacular pressure to 20 mm Hg or lower, in 56 eyes with medically uncontrollable primary open-angle glaucoma or secondary angle-closure glaucoma. In the former group, I achieved success in 85% of cases, 65% without further antiglaucomatous therapy. In the latter group, 59% obtained a successful result, 41% without additional treatment. The readings of applanation tonometry on the first postsurgical day were compared to those obtained after one year. Although approximately 50% of eyes in both glaucoma categories had an initially elevated pressure after trabeculectomy, it decreased steadily in most of those with primary open-angle glaucoma. In the secondary angle closure glaucoma population, this immediate postoperative ocular hypertension was significantly correlated with eventual failure of the operation.     

Malignant neoplasms metastatic to gingivae

Malignant neoplasms metastatic to the gingivae are rare. Our review of the literature revealed only eight acceptable examples. We are reporting two additional cases. One patient was a 58-year-old man with an adenocarcinoma of the lung which metastasized bilaterally to the maxillary gingiva. The second patient was a 27-year-old man with a synovial sarcoma which metastasized to multiple sites in the maxillary and mandibular gingiva. Clinically, gingival metastatic lesions are most often confused with hemangioma, pyogenic granuloma, giant-cell granuloma, and pepripheral fibroma. They usually occur late in the course of the disease and are associated with metastatic deposits in many other organs and tissues. Death usually occurs in a few weeks or months after discovery of the gingival metastasis.     

The effects of oral diazepam pretreatment on the biliary excretion of sulfobromophthalein in rats

Studies were performed with rats to examine the effects of single, as well as repetitive oral diazepam (DZP) pretreatment on biliary sulfobromophthalein (BSP) excretion rates and on bile flow parameters. One-hour pretreatment of male rats with 150 mg/kg of DZP resulted in about a one-third reduction in the peak biliary excretion rate of BSP (60 mg/kg, iv) and this was associated with a decrease in relative proportions of conjugated BSP in bile. The biliary excretion of preconjugated BSP was unaffected. BSP hepatic uptake and storage were apparently unaffected. In vitro DZP markedly inhibited BSP conjugating activity. In contrast to the above results, when BSP excretion was examined 1 h after the last of five daily oral doses of DZP (150 mg kg-1 day-1), no change in the peak elimination rate of this dye was evident. However, bile flow rates were higher in DZP-treated rats than in controls. When rats were examined 24 h after the last of five daily oral doses of DZP (150 mg/kg), the choleretic response persisted. Further studies showed that the repetitive DZP pretreatment enhanced the bile salt-independent mechanisms of bile formation.