Equilibrium vapour pressure of mercury from dental amalgam under loading conditions

Earlier studies have failed to establish a consensus on the amount of mercury vapour released from dental amalgam restorations. The purpose of this study was to accurately and quantitatively measure the equilibrium mercury vapour pressure from dental amalgam. The vapour pressure was measured using a quartz crystal microbalance as a function of the load from 0-5.4 MPa. Auger spectra were collected of the as-formed and argon ion sputter cleaned dental amalgam surface. For the as-formed surface the mercury vapour density is zero with no load and increases to 0.6 microg m(-3) at 5.4 M Pa. Following cleaning the mercury, vapour density increased to a maximum value of 15 microg m(-3). The Auger spectra of the as-formed surfaces were dominated by features associated with carbon and oxygen. These spectral results in concert with the mercury vapour density measurements indicate that the oxide film on the as-formed surfaces inhibited the release of mercury vapour. The results of this experiment provide an upper limit for the amount of mercury vapour released by dental amalgams. Under conditions simulating the oral cavity this value would be reduced by oxides that form on the surface of dental amalgam restorations.     

Effective oral ganciclovir prophylaxis against cytomegalovirus disease in heart transplant recipients

The presented data show the combined sequential use of i.v. G for 14 days followed by PO G for 90 days is a much more effective prophylaxis for CMVD after heart transplantation than use of i.v. G for 14 days followed by PO A for 90 days. A need for hospitalization due to CMVD is significantly reduced by this new strategy. The follow-up in group II is shorter than in group I but is now at least 6 months in group II, without any new cases in the first 6 months after cardiac transplantation. Some currently unknown adverse effect of prolonged PO G, which may be present, is not identified in this analysis.     

Murine bone marrow expressing the neomycin resistance gene has no competitive disadvantage assessed in vivo

The neomycin phosphotransferase (neo) gene is one of the most common marker genes used in gene transfer experimentation, but potential effects of neo gene expression in vivo have not been systematically investigated. Several early clinical retroviral gene transfer studies have suggested that neo gene expression could have deleterious effects on hematopoiesis, owing to a discrepancy between the level of neo-marked transduced marrow progenitor cells compared with mature circulating progeny cells posttransplantation (Brenner et al., 1993; Kohn et al., 1995; Brenner, 1996b). We examined the long-term in vivo repopulating ability of bone marrow from transgenic mice expressing neo from a strong constitutive promoter using a competitive repopulation assay. Different ratios of neo transgenic and wild-type congenic marrow cells were cotransplanted into W/Wv recipient mice. The percentages of blood cells containing the neo transgene in each group of recipient mice monitored for 4 months posttransplantation closely matched the input ratios of neo transgenic to congenic control marrow cells. Similar concordances of engraftment with input ratios of neo transgenic cells were also found in spleen, thymus, and whole marrow of recipient mice at 4 months posttransplantation. Analysis of the beta-hemoglobin phenotype (beta(single) for the neo transgenic and C57 control cells and beta(diffuse) for the congenic competitor HW80 cells) in recipients confirmed erythroid repopulation from neo transgenic marrow cells at levels matching the input ratios. We conclude that hematopoietic cells expressing neo had no engraftment or maturation defects detectable in vivo. These results suggest that the low-level contribution of vector-marked cells to circulating populations in clinical trials is not due to direct deleterious effects of neo gene expression on hematopoiesis.     

Time course of growth factor staining in a rabbit model of traumatic tractional retinal detachment

BACKGROUND: This study examined the relationship between growth factor expression and cellular proliferation during the evolution of traumatic tractional retinal detachment (TRD) in a rabbit model. METHODS: TRD was induced in 15 pigmented rabbits by treating the inferior retina with cryopexy and making a scleral incision superiorly. Sections from varied time points were stained in the same assay with mouse monoclonal antibodies (MAb) specific for basic fibroblastic growth factor (bFGF) and platelet-derived growth factor (PDGF-BB/AB). RESULTS: Initially, the eyes exhibited intense vitritis; discrete membranes were present at 7 days and progressed to tractional retinal detachment at 17 and 28 days, after which there was no clinical change. At 6 and 24 h, bFGF, PDGF, and proliferating cell nuclear antigen (PCNA) were not detectable in membranes or wound sites (except for PDGF-positive inflammatory cells). On days 7, 17, 28, and 52, bFGF and PDGF were readily detectable in most membranes. Cellular proliferation as detected by PCNA staining was also present on days 7, 17, and 28, but was absent by day 52 despite growth factor staining. At all times, PCNA staining, which was most intense at the wound site, showed only limited correlation with staining for either growth factor for individual cells. Müller cells stained positively for PDGF-BB/AB in 13 of the 15 TRD eyes, but in none of the normal eyes. CONCLUSIONS: Since cellular proliferation correlated incompletely with the staining for bFGF and PDGF, these growth factors may not account exclusively for cellular proliferation within the membrane. Their distribution, however, including PDGF staining of Müller cells and bFGF staining at the vitreous-membrane interface, suggests that they may have roles in the pathogenesis of TRD.     

Mechanical and histological fixation of hydroxylapatite-coated pyrolytic carbon and titanium alloy implants: a report of short-term results

Historically, pyrolytic carbon has been a material for cardiovascular applications, but it has several properties suited for orthopedic uses as well. Pyrolytic carbon has an elastic modulus similar to bone and is highly fatigue resistant, but has not been used in orthopedics because of poor fixation to bone. Plasma sprayed hydroxylapatite (HA) has significantly improved the bonding of bone to titanium alloy implants. The effect of plasma-sprayed HA on pyrolytic carbon implants was investigated in this study. Cylindrical samples were implanted through a single cortex in Beagle femurs. The animals were sacrificed after 8 weeks, and a mechanical push-out test was performed on the implants immediately after explantation. Samples were microradiographed, stained for histology, and examined histomorphometrically. Interface strength for each type of implant was calculated. Pyrolytic carbon showed almost no attachment strength with an average strength value of 1.59 MPa. HA-coated pyrolytic carbon (8.71 MPa) yielded the same interfacial strength as HA-coated titanium (8.71 MPa). Histology revealed that bone was in direct apposition to all implants, both HA coated and noncoated. Failures occurred between the core material and the coating, or within the coating, but not at the bone/HA interface. Histomorphometry results confirmed that the two types of HA-coated implants had more bone apposition than the uncoated pyrolytic carbon implants. It was concluded that a plasma sprayed HA coating significantly improves the bone fixation of pyrolytic carbon.     

Electron microscopic immunolocalization of caltrin proteins in guinea pig seminal vesicles

We report here on five new cases of solid and cystic papillary neoplasm (SCPN) of the pancreas diagnosed by fine-needle aspiration cytology (FNAC). All cytologic samples were obtained by ultrasonography, and the smears were conventionally fixed and stained. Special histochemical and immunocytochemical stains were also performed in some samples. Cytology revealed in all but one case numerous pseudopapillary structures composed of fibrovascular stalks lined with one or more layers of bland-appearing, uniform tumor cells. The tumor cells had round-to-oval euchromatic nuclei with frequently folded smooth contours and one or two small nucleoli. Their cytoplasm often contained eosinophilic, PAS-positive, and diastase-resistant inclusions. Foamy cells, psammoma bodies, blood, and cellular debris were found in the background. The criteria for the differential diagnosis versus other pancreatic lesions are discussed in some detail, as is the role of immunocytochemistry (ICC). In the literature, only 28 cases of cytologically investigated SCPN have been reported to the best of our knowledge. The most helpful criteria for the conclusive identification of SCPN by FNAC include the pseudopapillary arrangement with bland-appearing tumor cells, and, especially, the finding of acidophilic, PAS-positive, and diastase-resistant cytoplasmic granules.     

A liver-specific isoform of the betaine/GABA transporter in the rat: cDNA sequence and organ distribution

This paper discusses the findings of a quantitative study of nurses' willingness to care for patients with AIDS. It identifies several factors that enable nurses to confront the fear of AIDS nursing and to turn fear into compassion, and negative attitudes into positive ones. These factors include professional values, organizational support, group identity, patients' responses, spirituality, family and friends with AIDS, knowledge about AIDS, and the importance of personal choice. The value of these factors are further supported through personal statements made by nurses on AIDS-dedicated units as they express their feelings, thoughts, and positive experiences and expectations regarding AIDS nursing.     

Group and single-subject evaluation of a programme to promote self-care in elderly nursing home residents

Residents and staff of a nursing home in a metropolitan area were randomly assigned to three conditions to: (a) test whether staff's use of operant behavioural management strategies (Condition 1) would cause a greater increase in residents' self-care behaviour than staff's use of mutual goal setting (Condition 2) or routine nursing care (Condition 3), and (b) examine how useful group scores were, compared to individual scores, in determining change in individual residents' behaviour due to treatment. In-service training was provided to staff in Conditions 1 and 2 but not in Condition 3. Over a period of 22 weeks, nursing staff encouraged subjects to perform targeted self-care tasks independently. Data analysis indicated significantly greater change in self-care behaviours for subjects in Condition 1 than for subjects in Conditions 2 and 3. However, visual inspection of data for each case revealed that individual scores were more useful than averages and differences between groups for determining the effectiveness of the clinical interventions.     

Spatially varying Bayesian image estimation

OBJECTIVES: New methods are available to immortalize parenchymal cells from exocrine glands and kidney with retention of differentiation. Adaptation of this technology to small, single-donor biopsy material or surgical specimens could provide genetically homogeneous cells for functional analyses and correlation with genetic background and underlying biochemistry. To develop a methodology useful for renal sodium metabolism, epithelial cell line generation was tested in a hypertensive rat model with features similar to salt-sensitive hypertension in humans. This form of hypertension has a large genetic component and is prevalent in African Americans. DESIGN: Protocols were designed to immortalize primary cultures of microdissected proximal tubule epithelial cells from spontaneously hypertensive (SHR) and control, normotensive Wistar-Kyoto (WKY) rats. Immortalization was based on a replication-defective retrovirus coding for SV40 large T-antigen as positive cell cycle regulator. Transport competent cells that grow on porous filters to form confluent monolayers were selected. RESULTS: Several proximal tubule cell lines have been developed from SHR and WKY rats. The cells retain important differentiated features, such as epithelial polarity, low monolayer conductance, and sodium-succinate cotransport. They are suitable for analyses of electrolyte transport by electrophysiology or imaging of intracellular fluorescent indicator dyes, such as sodium-binding benzofuran isophthalate. CONCLUSION: Feasibility of generating epithelial cell lines from defined renal segments was demonstrated. The cells retain important transport function so that analyses of sodium metabolism and the influence of genetic background on it are possible. The methodology is applicable to human specimens.