Scattered radiation from dental metallic crowns in head and neck radiotherapy.

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

An experimental attenuation plate to improve the dose distribution in intraoperative electron beam radiotherapy for breast cancer.

Intraoperative electron beam radiotherapy (IOERT) is a technique in which a single-fraction high dose is intraoperatively delivered to subclinical tumour cells using an electron beam after breast-conserving surgery. In IOERT, an attenuation plate consisting of a pair of metal disks is commonly used to protect the normal tissues posterior to the breast. However, the dose in front of the plate is affected by backscatter, resulting in an unpredictable delivered dose to the tumour cells. In this study, an experimental attenuation plate, termed a shielding plate, was designed using Monte Carlo simulation, which significantly diminished the electron beam without introducing any backscatter radiation. The plate's performance was verified by measurements. It was made of two layers, a first layer (source side) of polymethyl methacrylate (PMMA) and a second layer of copper, which was selected from among other metals (aluminium, copper and lead) after testing for shielding capability and the range and magnitude of backscatter. The optimal thicknesses of the PMMA (0.71 cm) and copper (0.3 cm) layers were determined by changing their thicknesses during simulations. On the basis of these results, a shielding plate was prototyped and depth doses with and without the plate were measured by radiophotoluminescence glass dosimeters using a conventional stationary linear accelerator and a mobile linear accelerator dedicated for IOERT. The trial shielding plate functioned as intended, indicating its applicability in clinical practice.

Administration of anti-type II collagen antibody sustains footpad swelling of mice caused by a delayed-type hypersensitivity reaction and induces severe arthritis.

Delayed-type hypersensitivity (DTH) is an immune reaction induced by antigen. In the mice footpads at which DTH is elicited, transient swellings which usually peaks at 24-48 h after the antigen challenge are observed. We found that the footpad swellings of mice are sustained for at least 7 days after the antigen challenge if the mice were injected with anti-type II collagen monoclonal antibody (anti-CII MoAb) before the antigen challenge. A histological section of the swelled hindpaw revealed that severe joint inflammation and bone destruction was induced. These features were not observed in the footpads of the DTH-induced mice. Analysis of the inflammatory reaction induced by both the DTH and the anti-CII MoAb injection, here named as DTH arthritis, revealed the following: (1) DTH arthritis is elicited in an antigen-specific manner; and (2) the development of DTH arthritis is mediated by antigen-specific T cells, especially CD4+ T cells.

Calculation of 10 MV x-ray spectra emitted by a medical linear accelerator using the BFGS quasi-Newton method.

To calculate photon spectra for a 10 MV x-ray beam emitted by a medical linear accelerator, we performed numerical analysis using the aluminium transmission data obtained along the central axis of the beam under the narrow beam condition corresponding to a 3x3 cm2 field at a 100 cm distance from the source. We used the BFGS quasi-Newton method based on a general nonlinear optimization technique for the numerical analysis. The attenuation coefficients, aluminium thicknesses and measured transmission data are necessary inputs for the numerical analysis. The calculated x-ray spectrum shape was smooth in the lower to higher energy regions without any angular components. The x-ray spectrum acquired by the employed method was evaluated by comparing the measurements along the central axis percentage depth dose in a water phantom and by a Monte Carlo simulation code, the electron gamma shower code. The values of the calculated percentage depth doses for a 10x10 cm2 field at a 100 cm source-to-surface distance in a water phantom were obtained using the same geometry settings as those of the water phantom measurement. The differences in the measured and calculated values were less than +/-1.0% for a broad region from the shallow part near the surface to deep parts of up to 25 cm in the water phantom.

Ribozyme oligonucleotides against transforming growth factor-beta inhibited neointimal formation after vascular injury in rat model: potential application of ribozyme strategy to treat cardiovascular disease.

BACKGROUND: Because the mechanisms of atherosclerosis or restenosis after angioplasty have been postulated to involve an increase in transforming growth factor (TGF)-beta, a selective decrease in TGF-beta may have therapeutic value. Thus, we used the ribozyme strategy to actively cleave the targeted gene to selectively inhibit TGF-beta expression. METHODS AND RESULTS: We constructed ribozyme oligonucleotides (ONs) targeted to the sequence of the TGF-beta gene that shows 100% homology among the human, rat, and mouse species. The specificity of ribozyme against TGF-beta gene was confirmed by selective inhibition of TGF-beta mRNA in cultured vascular smooth muscle cells as well as balloon-injured blood vessels in vivo. Importantly, the marked decrease in TGF-beta resulted in significant inhibition of neointimal formation after vascular injury in a rat carotid artery model (P:<0.01), whereas DNA-based control ONs and mismatched ribozyme ONs did not have any inhibitory effect on neointimal formation. Inhibition of neointimal formation was accompanied by (1) a reduction in collagen synthesis and mRNA expression of collagen I and III and (2) a significant decrease in DNA synthesis as assessed by proliferating cell nuclear antigen staining. Moreover, we modified ribozyme ONs containing phosphorothioate DNA and RNA targeted to the TGF-beta gene. Of importance, modified ribozyme ONs showed a further reduction in TGF-beta expression. CONCLUSIONS: Overall, this study provides the first evidence that selective blockade of TGF-beta resulted in inhibition of neointimal formation, accompanied by a reduction in collagen synthesis and DNA synthesis in a rat model. We anticipate that modification of ribozyme ON pharmacokinetics will facilitate the potential clinical utility of the ribozyme strategy.

Transfection of antisense p53 tumor suppressor gene oligodeoxynucleotides into rat carotid artery results in abnormal growth of vascular smooth muscle cells.

BACKGROUND: Although loss of activity of an antioncogene, the p53 tumor suppressor gene product, has been postulated in the pathogenesis of human restenosis, little is known about the role of p53 in the regulation of vascular smooth muscle cell (VSMC) growth. In this study, to clarify the role of p53 in the pathogenesis of restenosis, we examined transfection of antisense p53 oligodeoxynucleotides (ODN) into VSMC in vitro and rat carotid artery in vivo. METHODS AND RESULTS: The specificity of antisense p53 ODN was confirmed by a significant decrease in p53 protein. Transfection of antisense p53 ODN into VSMC resulted in a significant increase in DNA synthesis and cell number as compared with sense and scrambled ODN (P<0.01). Importantly, transfection of antisense p53 ODN into rat intact carotid artery resulted in a significant increase in the ratio of neointima to medial area at 2 and 4 weeks after transfection, accompanied by a significant decrease in p53 protein (P<0.01). Moreover, cotransfection of wild-type p53 plasmid completely abolished neointimal formation induced by antisense p53 ODN. The sustained effect of a single antisense ODN administration was confirmed by the kinetics of ODN in the vessel wall with the use of FITC-labeled ODN. CONCLUSIONS: Overall, the present study demonstrated that loss of p53 by antisense p53 ODN resulted in an abnormal VSMC growth in vitro and in vivo. These results demonstrated the potential contribution of p53 to the pathogenesis of restenosis.

Prostaglandin E(2) and stem cell factor can deliver opposing signals to B lymphocyte precursors.

The synthetic prostanoid, 16,16-dimethyl PGE(2), suppressed B lymphopoiesis in mice and proliferation of normal B cell precursors or the F10 pro-B cell line to interleukin 7 in culture. This was not the case with two other prostanoids, PGD(2) and PGF(2alpha), or agonists for PGI(2) agonist and thromboxane A(2) agonist receptors. PGE(2), but not the related prostanoids or agonists, induced apoptosis in F10 cells. The apoptotic response was mediated by the EP2 class of PGE(2) receptors and required an increase in intracellular cyclic adenosine 3',5'-monophosphate, activation of protein kinase A, and protein synthesis. The influence of PGE(2) on F10 cells was diminished in the presence of a cloned stromal cell line or stem cell factor. These findings describe another potential regulatory circuit in bone marrow which might influence B lymphopoiesis under disease or steady-state conditions.

Indirect suppression of IL-7-responsive B cell precursors by vasoactive intestinal peptide.

Bone marrow is supplied with nerves and neuropeptides that influence a variety of cellular responses. This study represents an initial evaluation of vasoactive intestinal peptide (VIP) as a possible regulator of B lineage lymphocyte formation. As little as 10(-10) M concentrations of VIP inhibited the IL-7-driven clonal proliferation of pre-B cells in semisolid agar cultures. The response was blocked by a VIP antagonist and augmented by the ectoenzyme inhibitor, phosphoramidon. Suspensions of highly enriched B lineage precursors were unaffected by VIP unless they were cocultured with macrophage-like cells and conditioned medium from VIP-treated macrophages contained inhibitory activity. Neutralizing Abs were used to determine that IFN-alpha is at least one substance that is elicited by exposure of macrophages to VIP. These findings suggest that a neuropeptide can potentially modulate lymphopoiesis through a regulatory circuit that involves macrophages and IFN-alpha. They also raise the possibility that VIP can participate in antiviral defense.

Glycosylation of CD44 negatively regulates its recognition of hyaluronan.

Although CD44 is expressed on a wide variety of cell types, few of them use it to recognize the ligand hyaluronan (HA). A glycosylation-defective clone of Chinese hamster ovary cells (Lec 8) bound HA, demonstrating that complete processing of glycoproteins with addition of a full complement of sialic acid is not required. On the contrary, subsequent findings revealed that complex sugars on CD44 can actually inhibit ligand recognition. Two subclones of wild-type Chinese hamster ovary cells with similar amounts of surface CD44 were isolated on the basis of HA binding and found to differ with respect to CD44 size as well as staining with fluorescent lectins. Treatment of the nonbinding clone with tunicamycin reduced the size of the protein and allowed the cells to recognize HA via CD44. This function was also induced by treatment with deglycosylating enzymes (either a mixture of endoglycosidase F and N-glycosidase F or neuraminidase alone). A possible role for glycosylation in regulation of adhesion was then sought with a series of normal and transformed murine cells. Disruption of glycosylation or treatment with deglycosylating enzymes did not induce ligand binding in an interleukin 7-dependent pre-B cell line, and splenic B cells also appeared to be in an inactive state. Some normal B cells acquired the ability to recognize HA after stimulation with lipopolysaccharide or interleukin 5 and had distinctive surface characteristics (loss of immunoglobulin D and acquisition of CD43). An additional subset of activated cells might have been in a transitional state, because the cells bound ligand after neuraminidase treatment. The ligand-binding ability of a purified CD44-immunoglobulin fusion protein dramatically increased after neuraminidase treatment. Thus, differential glycosylation of this molecule is sufficient to influence its recognition function. Cell adhesion involving HA can be regulated by multiple mechanisms, one of which involves variable glycosylation of CD44.

Human immunoglobulin preparation for intravenous use induces elevation of cellular cyclic adenosine 3':5'-monophosphate levels, resulting in suppression of tumour necrosis factor alpha and interleukin-1 production.

We previously showed that human immunoglobulin preparation for intravenous use (IGIV) suppresses the in vitro production of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) by rabbit peritoneal exudate cells (PEC) stimulated with lipopolysaccharide (LPS). In this study we investigated the mechanism of the suppression. IGIV treated at pH4 (pH4-G) was used as IGIV. Fc fragments of pH4-G, as well as untreated pH4-G, suppressed TNF-alpha and IL-1 production by rabbit PEC stimulated with LPS. The interaction of pH4-G with PEC also resulted in generation of cyclic adenosine 3':5'-monophosphate (cAMP), known to be an intracellular second messenger. N6, 2'-0-dibutyryl cAMP (BtcAMP), a lipid-soluble derivative of cAMP, and cholera toxin (CT), an adenylate cyclase activating agent, also suppressed the production of TNF-alpha and IL-1. Further N-[2-(methylamino) ethyl]-5-isoquinolinesulphonamide dihydrochloride (H-8), an inhibitor of cAMP-dependent protein kinases, abrogated the suppression by pH4-G of the productions. These results indicate that the binding of IGIV to PEC via Fc gamma receptors (Fc gamma R) induces the elevation of intracellular cAMP levels, resulting in the suppression of LPS-induced TNF-alpha and IL-1 productions.

Therapeutic efficacy of granulocyte colony-stimulating factor alone and in combination with antibiotics against Pseudomonas aeruginosa infections in mice.

The therapeutic efficacy of granulocyte colony-stimulating factor (G-CSF) against an experimental intramuscular infection induced by Pseudomonas aeruginosa in mice was confirmed. Bacterial growth in the infected thigh muscle was suppressed by G-CSF treatment. The change in the number of peripheral blood polymorphonuclear leukocytes (PMN) after bacterial challenge was investigated. The results showed that G-CSF could stimulate stronger defense mechanisms after stimulation by bacterial challenge. In the G-CSF-treated group, more clusters of matured PMN were observed in the infected thigh muscle 6 h after bacterial challenge. Next, the correlation between the number of PMN in the blood at the time of infection and the therapeutic efficacy of antibiotics was investigated. The therapeutic efficacy of ceftazidime, a beta-lactam antibiotic, was affected by the number of blood PMN at the time of infection. In particular, a decrease of peripheral blood PMN at the time of infection resulted in a dramatic decrease in the efficacy of ceftazidime. The reduction in leukopenia by G-CSF remarkably strengthened the therapeutic effect of antibiotics in mice.

Suppression of tumor necrosis factor alpha production by a human immunoglobulin preparation for intravenous use.

We investigated the effect of a pH 4-treated human immunoglobulin preparation for intravenous use (pH4-G) on the production of tumor necrosis factor alpha (TNF-alpha) in vivo. The level of TNF-alpha in the sera of rabbits receiving pH4-G before lipopolysaccharide (LPS) injection was lower than that in rabbits receiving only LPS. Similarly, the in vitro production of TNF-alpha was suppressed by pH4-G. Rabbit peritoneal exudate cells stimulated with LPS in the presence of pH4-G produced less TNF-alpha than did those stimulated only with LPS. pH4-G, however, had no effect on various TNF-alpha activities, such as cytotoxicity against tumorigenic murine fibroblasts (L929 cells), induction of interleukin-1 production, or fever induction. These results indicate that pH4-G suppresses TNF-alpha production without affecting TNF-alpha activities. A suppressive effect on the expression of TNF-alpha mRNA was also observed.

[Molecular composite resins reinforced with polyaramides (Part 1). Molecular interaction between N-Octylated-Poly-p-Phenylene Terephthalamide (PPTA) as core molecule and PMMA and Polystyrene (PS) as matrices].

Molecular composite PMMA resin (Oct-PPTA-PMMA) can be reinforced with poly-N-octyl-p-phenylene terephthalamide (Oct-PPTA) as rigid core molecule. Compounding 3 wt% of Oct-PPTA to PMMA increased compressive, diametral and bending strength by 10 to 15%. The molecular interaction between Oct-PPTA as the core molecule and PMMA as a polar matrix and polystyrene (PS) as a non-polar matrix was examined with respect to dynamic viscoelasticity. Compounding 3 wt% of Oct-PPTA (Oct-PPTA-PS) to PS decreased compressive, diametral and bending strength by 15 to 30%. The dynamic storage modulus (G') value of Oct-PPTA-PS is lower than G' of PS in the region from rubbery state to viscous flow state. These results reveal a significant effect of the polar groups on the molecular interaction between the core molecule and matrices in the molecular composites compounding Oct-PPTA as core molecule.

Intramural giant gallstone: report of a rare case.

We report a case of intramural giant gallstone. Cholangiography revealed narrowing of the neck of the gallbladder due to a hemispherical prominence. At cholecystectomy, a giant gallstone 2.1 cm in diameter which was located in the submucosa of a hemispherical prominence at the neck of the gallbladder, was found. Although the usual sizes of intramural gallstones mentioned in previous reports have ranged from 2 to 5 mm in diameter, the stone found in our case is, as far as we know, the largest intramural gallstone yet reported.

Antipyretic activity of a human immunoglobulin preparation for intravenous use in an experimental model of fever in rabbits.

In an effort to elucidate the reason that fever in patients with severe bacterial infections subsided in some cases after the administration of human immunoglobulin preparations for intravenous use (IGIVs), we focused our attention on the antipyretic activity of IGIVs by investigating experimentally produced pyrexia in rabbits with Escherichia coli-derived lipopolysaccharide (LPS). Although little difference in antibody titers against the antigens composing molecules of LPS was found among the IGIVs that were used, IGIVs treated at pH 4 were demonstrated to inhibit a strongly LPS-induced second-phase febrile response, whereas the inhibitory effect of sulfonated and pepsin-treated IGIVs was weak. In vitro experiments on interleukin-1 production by rabbit macrophages stimulated with LPS, silica gel or latex beads and on rosette formation showed that these functions of the cells were also inhibited by IGIVs. The in vivo antipyretic activity and the results of the two in vitro experiments correlated closely. The inhibitory potency decreased in the following order: immunoglobulin G (IgG) treated at pH4, sulfonated IgG, and pepsin-treated IgG. Thus, it is possible that the subsidence of LPS-induced fever by IGIVs was mediated by inhibition of interleukin 1 production by means of binding of IgG to macrophages via an Fc receptor. Results of this study also indicated the importance of the structural integrity of the Fc portion of the IgG contained in the IGIVs to bind with its receptor on the macrophage so as to influence the various functions carried out by the cell.

Hemorrhagic necrosis of pheochromocytoma associated with reversible renal artery stenosis.

An unusual case of pheochromocytoma associated with renal artery stenosis is described. Despite the removal of bilateral adrenal pheochromocytoma, laboratory findings suggested the presence of residual pheochromocytoma and abdominal aortography revealed more pronounced stenosis of the right renal artery. Two months later, the undetected residual pheochromocytoma underwent hemorrhagic necrosis with acute cessation of catecholamine release. Thereafter, the patient's blood pressure decreased to a normal level with marked improvement in hypertensive symptoms. No remaining stenosis was demonstrated on follow up renal angiography. Our case suggests that constant local secretion of catecholamines may be responsible for the development of renal artery stenosis.