The "How!" sign--a central palmar blister induced by overplaying on a Nintendo console.
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Blister↗
Biomedical subjects
D J Wood
Publications and source records attributed to D J Wood.
The histogenesis of giant cell tumour of bone: a model of interaction between neoplastic cells and osteoclasts.
Giant cell tumour of bone (GCT) is a benign primary neoplasm of a bone characterised by distinctive clinical, radiological and pathological features. Females are slightly more often affected than males, and the majority of patients present between the ages of 20 and 50. GCT is locally aggressive and produces expansive and lytic lesions, most commonly in the epiphyses of long tubular bones. Histologically, it is composed of oval and spindle mononuclear cells, uniformly distributed amongst which are large multinucleated osteoclast-like giant cells. Although the term "Giant Cell Tumour" (and the erroneous historical term 'osteoclastoma') may imply that it is the multinucleated giant cells which are responsible for the proliferative capacity of the tumour, there is evidence that the stromal-like cells, the major component of the mononuclear cell population, represent the true neoplastic component of the neoplasm. The diagnosis and management of conventional GCT are often challenging and there is considerable current interest in its pathobiology. The precise histogenesis of GCT and the nature of its varying cellular constituents have remained a matter of some controversy. Factors influencing the clinical course and biological aggression of GCT are also unclear. In this selective review, the clinicopathological characteristics of GCT are summarised and current areas of interest in the study of the neoplasm are presented and discussed. Lastly, a hypothetical model of the mechanism of histogenesis and the biological behaviour of GCT is presented.
Animals↗
Alterations in the adhesion behavior of osteoblasts by titanium particle loading: inhibition of cell function and gene expression.
Total joint replacement prostheses are required to withstand corrosive environments and sustain millions of loading and articulation cycles during their term of implantation. Wear debris generation has been implicated as one of the primary causes of periprosthetic osteolysis and subsequent implant loosening in total joint replacements. Particulate debris consisting of metals, polyethylene, ceramics, and bone cement have each been shown to provoke a biological response in joint tissues. The major cell types within the interfacial granulomatous fibrous tissues consist of fibroblasts, macrophages, lymphocytes, and foreign-body giant cells. Osteoblasts are one of the principal cell types in the bone tissue adjacent to prostheses, maintaining physiologic bone remodeling through the balanced coordination of bone formation and resorption in concert with osteoclasts. To date the phenomenon of osteoblast phagocytosis of titanium particles has been suggested, but has not been sufficiently studied or confirmed. This study seeks to clarify the influence of titanium particles on osteoblast adhesion, deformability, proliferation, and gene expression profile. These studies were accomplished by performing biorheological testing, Northern blot analysis and RNase protection assay. The uptake of metallic particles by the osteoblast resulted in a particle-filament complex formation, which induced a series of variations in cell function. Understanding these variations is critical to expanding our knowledge of implant loosening and elucidating the nature of prosthetic joint failure. This study suggests that the impact of titanium particles on osteoblast function and subsequent implant loosening may have been previously underestimated.
Actin Cytoskeleton↗
The vaccine origin of the 1968 epidemic of type 3 poliomyelitis in Poland.
A clear association was demonstrated between the use of USOL-D-bac type 3 poliovirus live-attenuated vaccine and the 1968 poliomyelitis epidemic in Poland. The epidemic followed small-scale trials with Sabin and USOL-D-bac type 3 vaccine strains carried out in seven countries including Poland. Factors that might have contributed to the genesis and development of the epidemic were the pattern of virus excretion from vaccinees, mutations found in viruses from the epidemic, and the particular vaccination policies in Poland during the previous years. These findings may provide essential insights into the strategies for stopping polio immunisation once wild poliovirus has been eradicated.
Antigens, Viral↗
Preparation, characterization, X-ray crystal structure, and energetics of cesium 5-cyano-1,2,3,4-tetrazolate: Cs[NCCNNNN].
Cesium 5-cyano-1,2,3,4-tetrazolate, Cs[NCCNNNN] (Cs1), was prepared in 100% yield by a 3 + 2 cycloaddition reaction of CsN3 and (CN)2 in SO2. Cs1 forms monoclinic crystals (a = 8.297(2) A, b = 11.040(3) A, c = 6.983(2) A, beta = 120.31(2) degrees, space group C2/c, Z = 4, R1 = 0.048, wR2 = 0.120 for 1217 independent reflections). Cs1 is best described as a three-dimensional array of cations and anions connected by weak Cs(+)-N delta- contacts. The cations and anions each form a diamond-type lattice (tetrahedral arrangement of ions) with the counterions lying in hexagonal channels running parallel to the c-axis. The anions in the channels form stacks with the CN groups pointing in opposite directions in adjacent layers. The calculated (RB3PW91/6-311 + G*) geometry of 1 is in agreement with the X-ray crystal structure, and the calculated vibrational spectrum is in good agreement with the observed FT-IR and FT-Raman spectra. The lattice enthalpies and heats of formation of M1 (M = Cs, K) as well as the enthalpy of formation from MN3(s) and (CN)2(g) were estimated. The 13C and 14N NMR spectra of Cs1 are also reported. The ionization potential (450.7 kJ mol) and electron affinity (427.4 kJ/mol) of 1 were calculated. Attempts to oxidize 1 with AsF5 led to the formation of Cs1.xAsF5 (x approximately 2). The 7 pi dianion [NCCNNNN].2- is calculated to be a stable entity in the gas phase, but Cs(2)1 is estimated to be unstable with respect to dissociation to 2 CsCN and 3/2 N2 (delta Hdiss = -132.4 kJ/mol). The preparation of the potassium salt of 1 and the corresponding thermodynamic quantities are reported.
Journal Article↗
Titanium particles inhibit osteoblast adhesion to fibronectin-coated substrates.
To illuminate the effect of titanium particles on osteoblast function, we compared the adhesion force of neonatal rat calvarial osteoblasts on fibronectin-coated glass after incubation with titanium particles (80% had diameters of less than 5 microm). The cells were incubated with the particles for 1.5-72 hours. Using a micropipette single-cell manipulation system, we showed that the adhesion force of the osteoblasts to fibronectin-coated glass (1.0 microg/ml) was significantly affected by the presence of particulate debris. The adhesion force of the cells incubated with titanium particles for less than 4 hours was not significantly affected by exposure to the particles; after 4 hours, however, it was significantly reduced relative to that of controls. Aspiration of particle-challenged osteoblasts into the micropipette demonstrated that the particles were not stripped from the cell surface and therefore confirmed that the osteoblasts had ingested them. During aspiration, the particles traveled through the cytoplasm rather than on the cell surface. When the osteoblasts were exposed to the particles and cytochalasin D, they exhibited much lower adhesion forces than did the controls or the cells exposed to titanium particles only; this indicates an important role of actin filaments in the osteoblastic response to particles. Staining for F-actin also indicated an influence of internalized titanium particulate on cytoskeletal arrangement and cell spreading. Furthermore, with standard Northern blotting techniques, levels of mRNA for collagen type I and fibronectin were significantly reduced as early as 4 hours after exposure to particles compared with levels in controls, and this effect continued to 72 hours. These data indicate that direct exposure of osteoblasts to titanium particles, which we propose to be ingested by the osteoblasts, can significantly decrease osteoblast adhesion force; this may lead to decreased cellular activity and gene expression of fibronectin and collagen type I in the presence of titanium wear debris.
Actins↗
WHO Expert Committee on Biological Standardization: highlights of the 50th meeting, October 1999.
Biological medicines, which include vaccines, blood products and biological therapeutics, have historically played a dominant role in improving world health and are expected to make an increasingly important contribution to public health in the 21st century. Recent scientific and biotechnological developments have opened the way to novel products, new production methods and to highly sensitive assay procedures. However, the nature of biologicals, and especially new vaccines, blood products and therapeutics, raises particular questions regarding their standardization and quality control. These relate both to efficacy and to safety not only for the individual recipient but also for the population at large. Such advances highlight the complex issues surrounding standardization and control of biologicals, issues that need to be addressed on an international level.
Biological Factors↗
Gene expression of osteoprotegerin ligand, osteoprotegerin, and receptor activator of NF-kappaB in giant cell tumor of bone: possible involvement in tumor cell-induced osteoclast-like cell formation.
Giant cell tumor of bone (GCT) is a rare primary osteolytic tumor of bone that is characterized by massive tissue destruction at the epiphysis of long bones. There is no evidence that tumor cells themselves are capable of bone destruction; instead, it appears that the tumor cells of GCT act by promoting osteoclastogenesis and, as a consequence, osteoclastic bone resorption. However, the mechanism by which this is achieved is not understood. Here we attempted to determine whether osteoprotegerin ligand (OPGL), the factor that is necessary and essential for osteoclastogenesis, is involved in tumor cell-recruited osteoclast-like giant cell formation in GCT. Using fluorescence in situ hybridization, we sought to determine mRNA expression of OPGL, its receptor RANK, and its decoy receptor OPG in three major cell types of GCT. We demonstrated that OPG mRNA was expressed in all three cell types of GCT, OPGL transcripts were mainly detected in spindle-shaped stromal-like tumor cells, whereas RANK was expressed only in macrophage-like mononuclear cells and multinuclear osteoclast-like giant cells. By semiquantitative RT-PCR, we also showed that the level of OPGL mRNA in GCT is much higher than that in normal bone and osteogenic osteosarcoma. In contrast, a similar level of OPG transcripts was detected in these three kinds of tissues, and RANK mRNA was detectable only in GCT tissues. We have further examined the regulation of gene expression of OPGL and OPG in tumor cells in response to osteotropic hormones. Administration of 1,25(OH)(2)D(3) and dexamethasone resulted in maximum up-regulation of OPGL level and down-regulation of OPG level in cultured GCT stromal-like tumor cells and the mouse bone marrow-derived ST-2 stromal cell line. Furthermore, we have shown that tumor cells of GCT induce differentiation of RANK-expressing myeloid RAW(264.7) cells into osteoclast-like cells in the presence of 1,25(OH)(2)D(3) and dexamethasone. Our findings suggest that OPGL is involved in the tumor cell-induced osteoclast-like cell formation in GCT. The ratio of OPGL/OPG by tumor cells may contribute to the degree of osteoclastogenesis and bone resorption.
Animals↗
Whiplash rove beetle dermatitis in central Queensland.
Vesicular dermatitis due to contact with Coleoptera (beetles) is common worldwide, although the condition has been infrequently described in Australia. We document the largest outbreak recognized so far in Australia with a conservative estimate of 250 cases. This occurred in central coastal Queensland over several weeks in late 1998. A survey of the medical practitioners in this district is presented, along with clinical and histopathological illustrations. Our research found that knowledge of the condition was limited even in this region where cases occur each year. This condition is an important differential diagnosis in acute blistering disorders.
Animals↗
Gene expression of vascular endothelial growth factor in giant cell tumors of bone.
The production of vascular endothelial growth factors (VEGF), a major cause of neoangiogenesis, is a prerequisite for tumor growth and invasion. VEGF have also been shown to be important for the formation of osteoclasts. Because giant cell tumors of bone (GCT) are frequently hypervascular and have the ability to recruit macrophages and multinucleated osteoclast-like giant cells, we evaluated the levels of VEGF gene transcript in several of these tumors using Northern blot analyses, semiquantitative reverse transcription polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and immunohistochemistry. Our results showed that three major isoforms of VEGF (121, 165, and 189) were expressed in all cases of GCT investigated, with isoform 121 transcripts the most abundant. By both FISH and immunohistochemistry, we have shown that VEGF was present in spindle-shaped stromal-like tumor cells, round macrophage-like cells, and osteoclast-like multinucleate giant cells. Moreover, we have shown that the levels of VEGF gene expression but not microvessel density correlated with Enneking's clinical stage of GCT. There were higher levels of VEGF gene expression in stage III GCT than in stage I/II GCT (P < .0357). In conclusion, our results indicate that overexpression of VEGF may be associated with the advanced stage of the neoplasm.
Adult↗
The effect of early static loading on the in vitro shear/peel bond strength of a 'no-mix' orthodontic adhesive.
This study addressed the question of whether shear and tensile loads applied 15 minutes after bonding metal brackets to enamel affected the shear/peel bond strength of the adhesive. Ninety standard 0.022-inch stainless steel edgewise premolar mesh-backed brackets were bonded using a no-mix chemical-cured adhesive to 90 teeth, which had been prepared in a standardized manner. After 15 minutes three groups of 30 teeth were subjected to the following regimes: no applied load, tensile static load of 0.77 N (78 g), and shear static load of 0.77 N. After 14 days storage in 100 per cent relative humidity at 37 degrees C, the shear/peel strength of the adhesive bond was measured using a purpose built jig mounted on a universal testing machine. Shear/peel bond strengths were analysed using Weibull statistics. The Weibull moduli of the three groups indicated that the adhesive performed consistently despite early static loading. Characteristic strengths were 9.22, 9.27, and 9.05 MPa for the control, tensile, and shear groups, respectively. The findings indicate that static loads (such as tying in of archwires) can be placed on brackets 15 minutes after cementation, without a clinically significant reduction in bond strength of the tested adhesive.
Bisphenol A-Glycidyl Methacrylate↗
Investigation of a hydrophilic primer for orthodontic bonding: an in vitro study.
A common reason for bond failure is moisture contamination. This study investigates the in vitro bond strength of brackets bonded using a new hydrophilic primer, designed to be insensitive to moisture, and compares it with a conventional primer. Using a standardized technique, the in vitro bond strength of brackets bonded with the hydrophilic primer was compared to identical brackets bonded with a conventional primer. Although designed to be moisture insensitive, the directions for use stipulate drying the teeth before bonding. Therefore, for the purposes of comparison with a conventional primer the experiment was conducted under dry conditions. The results were analysed using the Weibull distribution modelling. The median bond strength with the hydrophilic primer (6.43 MPa, 95 per cent C.I. 7.69-9.50) was significantly lower (P = 0.0001) than the conventional primer (8.71 MPa, 95 per cent C.I. 5.89-7.59). The Weibull distribution modelling showed that brackets bonded with the hydrophilic primer were 3.96 times more at risk of failure (95 per cent C.I.: 2.39-6.56; P <0.0001). The bond strength at which 5 per cent of the brackets failed was also lower for the hydrophilic primer. The bond strengths obtained with the hydrophilic primer were significantly lower than with the conventional primer. Although the median bond strength values were promising, the laboratory results for this particular hydrophilic primer were disappointing when using the Weibull analysis, where the whole distribution of bond strength is taken into account.
Adolescent↗
Using a cognitive architecture to examine what develops.
Different theories of development propose alternative mechanisms by which development occurs. Cognitive architectures can be used to examine the influence of each proposed mechanism of development while keeping all other mechanisms constant. An ACT-R computational model that matched adult behavior in solving a 21-block pyramid puzzle was created. The model was modified in three ways that corresponded to mechanisms of development proposed by developmental theories. The results showed that all the modifications (two of capacity and one of strategy choice) could approximate the behavior of 7-year-old children on the task. The strategy-choice modification provided the closest match on the two central measures of task behavior (time taken per layer, r = .99, and construction attempts per layer, r = .73). Modifying cognitive architectures is a fruitful way to compare and test potential developmental mechanisms, and can therefore help in specifying "what develops."
Adult↗
Stopping poliovirus vaccination after eradication: issues and challenges.
Since 1988 reported polio cases worldwide have declined by about 85% and the number of known or suspected polioendemic countries has decreased from over 120 to less than 50. With eradication of poliomyelitis approaching, issues potentially affecting when and how vaccination against poliovirus can be stopped become extremely important. Because of the potential risks and benefits inherent in such a decision, the best available science, a risk-benefit analysis, contingency plans, a stock pile of poliovirus vaccines, and the endorsement by the global policy-making committees will all be needed before vaccination can be discontinued. The scientific basis for stopping polio immunization has been reviewed by WHO. This Round Table article summarizes the current state of knowledge, provides an update on the processes and timelines for certification, containment, and stopping vaccination, and highlights some of the unanswered scientific questions that will be addressed by further research. These include whether transmission of vaccine-derived poliovirus strains could be sustained so that poliomyelitis could re-emerge in a future unvaccinated population and whether prolonged excretion of vaccine-derived poliovirus from individuals with immune deficiencies could be a mechanism through which this could occur.
Biological Warfare↗
Australia's last reported case of wild poliovirus infection.
In 1986 tests on faeces collected from a 22 year old Australian born man who had symptoms consistent with poliomyelitis yielded poliovirus type 3. In a neutralisation test using a panel of monoclonal antibodies the isolate was identified as wild poliovirus type 3 at that time. After further classification using microneutralisation, nucleic acid probe hybridisation, immunoassay and sequencing carried out in three laboratories between 1994 and 1997, the isolate has been reclassified as 'Sabin-like' with 'wild type' characteristics. This case has been quoted in the literature as Australia's last case of locally acquired wild poliovirus. Efforts are now being made to identify the true last case in Australia. This article describes the isolation, identification and further characterisation of this virus.
Adult↗
Examination of poliovirus vaccine preparations for SV40 sequences.
Oral poliovaccines derived from the strains developed by Sabin have been the basis of vaccination against poliomyelitis in the U.K. since 1962. Contamination of earlier materials with the monkey virus SV40, particularly inactivated Salk type poliovaccines, is well documented. Precautions have been in place for more than 30 years to prevent SV40 contamination of oral poliovaccines based on screening of donor animals and tests for SV40 infectivity. PCR was applied to examine all archived samples of oral poliovaccines available to us dating from 1966 to the present, including all vaccines used in the U.K. since 1980, for the presence of SV40 sequences. Of 132 materials examined, 118 were negative on initial testing and fourteen gave reactions which on further examination were attributed either to cross contamination during handling in the laboratory at National Institute for Biological Standards and Control (NIBSC) or to non-specific amplification. It was concluded that none of the samples contained SV40 sequences. The materials included 69 separate monovalent bulks of poliovirus type 1, 2 or 3 grown on monkey kidney cells from four different manufacturers and 74 bulks grown on human diploid cells from two manufacturers. One additional seed material from 1962 contained low levels of unique and characteristic SV40 sequences. The seed had been treated by the manufacturer to inactivate DNA viruses and tests by the manufacturer and at NIBSC failed to demonstrate the presence of infectious SV40 virus. Monovalent bulks prepared by the manufacturer from this seed were negative for SV40 sequences by PCR. The PCR studies provide no evidence of contamination of oral poliovaccines used in the UK with infectious SV40 and suggest that the steps taken to ensure the absence of infectious SV40 are satisfactory.
Animals↗
Re: Laboratory tests for live attenuated poliovirus vaccine. Subhash C. Arya; Biologicals, Volume 26, pp. 245-246, 1998.
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Drug Industry↗
A fluid filtration and clearing technique to assess microleakage associated with three dentine bonding systems.
OBJECTIVES: The aims of this in vitro study were to (a) measure fluid flow through teeth restored with one of three dentine bonding systems and a resin composite restoration; (b) measure the distribution of a silver tracer through the same teeth, and make a comparison with fluid flow; and (c) investigate the effect of thermocycling on both measurement types. METHODS: Coronal segments of 30 premolars, randomly allocated to three equal groups, were assessed by fluid filtration. Each group was restored with a resin composite restoration in conjunction with Fuji Bond LC (FBLC), Scotchbond Multi-Purpose Plus (SMP+) or Prime&Bond 2.1 (P&B2.1). Fluid filtration rates were measured in the intact crown and then after cavity preparation, conditioning, dentine bonding, restoration and at 2 and 24 h, 1 week and 1 month following restoration. Six specimens from each group were thermocycled at 1 week. After final filtration measurements the specimens were perfused with silver nitrate and cleared before scoring tracer penetration. RESULTS: No significant differences (P > 0.05) in fluid filtration rates were found amongst the different bonding systems or at any restoration stage. Thermocycling was not associated with any significant (P > 0.05) increase in fluid filtration. Final fluid filtration and tracer distribution showed a weak and not statistically significant correlation (P > 0.05). The penetration of silver stain indicated a failure of the restorations to seal the cavity and demonstrated a possible pathway by which in vivo post-operative sensitivity could occur. CONCLUSIONS: Although not statistically significant, conditioning of the cavity increased the dentinal permeability but this effect was variable. Thermocycling had no statistically significant effect on microleakage.
Analysis of Variance↗