The cross‐pin retained implant supported restoration: a study of gasket placement and leakage

Background: Advantages of cross‐pin retained implant supported restorations (ISRs) include predictable retrieval and predictable retention. Unlike direct to fixture (DTF) or cement retained restorations, the prosthetic design of a cross‐pinned restoration retains gaps at the interfaces between the crown, abutment and cross‐pin screw. These spaces permit leakage into the suprastructure and gasket placement has been recommended to prevent this leakage. Methods: Five different gaskets were assessed for their ability to prevent leakage into a cross‐pinned ISR. The gaskets tested were: cement admixture on the cross‐pin screw; cement admixture on the inner surface of the coping and the cross‐pin screw; cement admixture on the inner surface of the coping only; cement admixture placed 1 mm from the margin of the coping and a filler placed in the abutment chimney. Results: Only gaskets which sealed both the cross‐pin screw interface and the abutment‐crown interface prevented leakage. A filler placed in the abutment chimney prevented leakage into this space but did not prevent fluid accumulating between the coping and abutment. Conservative placement of cement at the margin of the coping failed to prevent leakage. Conclusions: Cement gaskets may effectively prevent leakage into a cross‐pinned ISR. However, the use of a cement as a gasket has to be weighed against the issue of predictable retrieval, cement extrusion and incomplete seating.     

Establishment of erythropoiesis following bone marrow transplantation in a patient with congenital hypoplastic anemia (Diamond-Blackfan syndrome)

Marrow transplantation was attempted in a 13-yr-old boy with congenital hypoplastic anemia who had never responded to corticosteroid therapy. Prior to the transplant, he had received 238 transfusions, at least 12 of which were from his father. He was prepared for grafting with antilymphocyte globulin, procarbazine, and total body irradiation (1000 rads). The patient, whose red cells were Group B, then received marrow cells from his Group O, histocompatible, sister. Thereafter, reticulocytes, Group O erythrocytes, and female leukocytes appeared in the peripheral blood. Erythroid precursors were seen in the patient's marrow for the first time in his life, and all lacked fluorescent Y chromosomes. Dividing cells were all female. After initially progressing well, the patient developed interstitial pneumonia and died 55 days after the transplant. The successful erythroid graft suggested that this patient's failure to produce red blood cells was due to a defective stem cell rather than to a humoral defect, plasma inhibitor, or abnormal marrow microenvironment. It suggested further that sibling marrow may be engrafted in patients who have received multiple transfusions, even from a parent.     

Interleukin 2 induction of lymphokine-activated killer (LAK) activity in the peripheral blood and bone marrow of acute leukemia patients. I. Feasibility of LAK generation in adult patients with active disease and in remission

The feasibility of in vitro interleukin 2 (IL-2) activation and expansion of mononuclear cells (MNCs) derived from adult patients with acute myelogenous leukemia (ANLL) was studied. Patients' natural killer (NK) and lymphokine-activated killer (LAK) cell activity was compared with that of normal donors in terms of: (a) cytolytic activity (four- hour 51Cr release assay) against an NK-sensitive target (K562), NK- resistant targets (Raji/Daudi), and fresh/cryopreserved autologous and allogeneic leukemic blasts; (b) proliferation and expansion in culture with 1,000 U/mL recombinant IL 2 (rIL 2); and (c) the cell surface phenotype of the cultured cells. In 21 of 24 patients with active disease (AP) MNCs derived from the peripheral blood (PBL) or bone marrow (BM) could be cultured and expanded in the presence of rIL 2. These cultures initially contained between 30% and 50% blasts, and during 2 to 4 weeks of culture destruction of blasts and enrichment of up to 60% in cells with the morphology of large granular lymphocytes (LGLs) was observed. Expansion in culture varied between two- and 100- fold. MNCs from all patients in remission (RP) could be activated by rIL 2 and expanded up to 30-fold after 1 to 3 weeks in culture. NK activity of fresh PBLs from AP was significantly lower than in normal controls, whereas NK activity of RP was within the normal range. High levels of postactivation NK and LAK activity on K562/Raji/Daudi and on fresh/cryopreserved leukemic blasts was generated in approximately 50% of cases of AP and in most RP. Cell surface phenotype studies showed that cultured cells derived from ANLL patients were significantly enriched (up to 40%) in NKH-1 (Leu 19) positive cells, with RP LAK cells also expressing a high proportion of CD16 positive cells (up to 40%). This study has shown that it is feasible to activate and significantly expand killer cells derived from active disease and remission ANLL patients during 1 to 3 weeks culture with IL 2 with good maintenance of cytolytic activity. Both initial NK activity and LAK generation was optimal in remission patients. Based on data from this study, a clinical protocol has been developed for treatment of early relapse ANLL patients with LAK cells cultured for 1 to 3 weeks and systemic IL 2.     

On the inclusion of prevalent cases in HIV/AIDS natural history studies through a marker-based estimate of time since seroconversion

In most cohort studies of HIV infection and AIDS, seroprevalent cases provide a substantial amount of information. Inclusion of these people in natural history studies requires a fairly unbiased method to estimate their seroconversion distribution. When a cohort-based estimate is not feasible, an alternative is to estimate individual seroconversion distributions, based on marker values at entry. In this paper, a non-parametric marker-based estimation method is developed. The method is applied to data from the Amsterdam cohort study on homosexual men. For seroprevalent cases who entered the study between October 1984 and April 1985, individual seroconversion distributions are estimated based on their first measured CD4 count. In subsequent survival analyses, dates of seroconversion are estimated via conditional mean imputation. Inclusion of these seroprevalent cases greatly improves the quality of the data. Age at seroconversion is a significant cofactor for disease progression, a result not found when analysis is restricted to those who seroconvert. To incorporate the uncertainty in the imputed date of seroconversion, a bootstrap procedure is developed for the computation of p-values and confidence intervals. In our analyses, standard procedures, which ignore the uncertainty in the imputed date of seroconversion, perform almost as well.     

Increased level of polymerase Ⅲ transcribed Alu RNA in hepatocellular carcinoma tissue

There have been extensive observations that RNA containing repetitive elements accumulates in transformed cells and tumor tissues. In the present study, we first obtained result consistent with previous observations by in situ hybridization.     

Seizures in children with low-grade tumors： outcome after tumor resection and risk factors for uncontrolled seizures

OBJECT： The goals of this study were to define the incidence of seizures in children with low-grade tumors, study seizure outcome after lesionectomy in these children, and identify risk factors for poor seizure outcome, METHODS： The authors performed a retrospective chart review of children who harbored low-grade brain tumors, experienced seizures, and were treated in a single institution, Statistical analyses included step-wise as well as single-variable binary logistic regression analyses.     

Ki-ras mutations are an early event and correlate with tumor stage in transplacentally-induced murine lung tumors

A previous study from this laboratory demonstrated that treatment of pregnant mice with 3-methylcholanthrene (MC) caused lung tumors in the offspring at 1 year after birth, the incidence of which correlated with fetal inducibility of Cyp1a1. Analysis by PCR amplification and allele- specific hybridization (ASO) of paraffin-embedded tumors generated from that study revealed the presence of point mutations in exon 1 of the Ki- ras gene. This work has now been expanded by PCR amplification and ASO analysis of 31 additional lesions. Point mutations were found in 37 of the 47 (79%) lesions analyzed in this and the previous study, the majority of which were G-->T transversions in the first or second base of codon 12. The mutational spectrum appeared to be dependent on the relative stage of differentiation of the lesion, as both the incidence of mutation and type of mutation produced correlated with malignant progression. Mutations occurred in 60% of the hyperplasias, 80% of the adenomas and 100% of the adenocarcinomas. In the lesions with mutations, GLY12-->CYS12 transversions occurred in 100% of the hyperplasias, 42% of the adenomas and 14% of the adenocarcinomas. The GLY12-->VAL12 transversions occurred in none of the hyperplasias, 42% of the adenomas and 57% of the adenocarcinomas. The remaining mutations, which consisted of ASP12 transitions and ARG13 transversions, occurred only in adenomas (17%) and adenocarcinomas (29%). Between this study and our previous analyses, the identity of the mutations obtained by ASO were confirmed by sequence analysis of eight of the 37 lesions that harbored mutations at the Ki-ras gene locus. There were no differences in the type or incidence of mutations relative to the metabolic phenotype or sex of the mice. These data suggest that mutational activation of the Ki-ras gene locus is an early event in transplacental lung tumorigenesis, and that the type of mutations produced by exposure to chemical carcinogens can influence the carcinogenic potential of the tumor. This may have prognostic significance in determining the malignant progression of the neoplasm.      

The ultra-low resistance Groningen voice prosthesis: aerodynamic properties

Post-laryngectomy voice rehabilitation using the low resistance (LR) Groningen voice prosthesis has over the past years provided good voice and speech results. The valve part of the prosthesis is largely responsible for the airflow resistance of the prosthesis. This study was performed to evaluate if by modifying the valve part of the LR Groningen prosthesis a lower airflow resistance in vitro could be achieved. Several prototypes with modified valves were tested. Based on the aerodynamic measurements the prosthesis with a single slit of 200 degrees in the 'hat' of the esophageal flange was selected for further evaluation and named the ultra-low resistance (ULR) Groningen voice prosthesis. Aerodynamic measurements were performed and showed the airflow resistance of the ULR Groningen voice prosthesis to be significantly lower than the resistance of the LR Groningen and the Provox voice prostheses.     

Early pregnancy complications: endovaginal sonographic findings correlated with human chorionic gonadotropin levels

Endovaginal sonography results were compared with quantitatively determined human chorionic gonadotropin (hCG) levels in 84 women referred for early pregnancy complications. Of the 27 with normal intrauterine pregnancies, an intrauterine gestational sac was prospectively identified in one of five cases (20%) in which hCG levels were below 500 IU/L (Second International Standard), four of five (80%) with hCG levels of 500-1,000 IU/L, and all 17 with hCG levels above 1,000 IU/L. In comparison, 17 of the 26 women with ectopic pregnancies (65%) had hCG levels greater than 1,000 IU/L, and none of the 26 had an intrauterine gestational sac. Endovaginal sonography demonstrated an adnexal mass and/or a gestational sac-like structure in 16 of the 17 cases (94%) in which hCG levels were above 1,000 IU/L, compared with only three of the nine (33%) with lower hCG levels (P less than .01). These findings indicate that an intrauterine gestational sac should be normally visualized with endovaginal sonography when the hCG level exceeds 1,000 IU/L, and that visualization of an extrauterine gestational sac and/or adnexal mass is significantly more likely in ectopic pregnancies when the hCG level exceeds 1,000 IU/L.