Characterisation and mechanical testing of hydrothermally treated HA/ZrO2 composites.

Hydrothermal treatment is traditionally employed to improve the sinterability of powder compacts by reducing porosity and increasing apparent density. The effect of hydrothermal treatment on green powder compacts has been assessed in order to better understand how treatment may affect the sinterability of the bodies. Laboratory synthesised nano sized hydroxyapatite (HA) and a commercial zirconia (ZrO(2)) powder have been ball milled together to create composite mixtures containing 0-5 wt% ZrO(2) loadings. Disc shaped bodies have been formed using uniaxial and subsequent isostatic pressure. The resultant coherent samples were subjected to hydrothermal treatment at either 120 or 250 degrees C for 10 h in order to assess the effect of this processing technique on the physical, mechanical and microstructural properties of the green composites. ZrO(2) loadings up to 3 wt% increased apparent density from 90 to 92%, whereas increased loading to 5 wt% increased flexural strength, from 6 to 9 MPa. Increasing the hydrothermal treatment temperature increased open porosity, from ~44 to ~48% and reduced biaxial flexural strengths of the treated bodies compared to those of their room temperature isostatically pressed counterparts (~10 to ~6 MPa).

Treatment of mildly to moderately active ulcerative colitis with a tryptase inhibitor (APC 2059): an open-label pilot study.

BACKGROUND: Mast cells isolated from the colonic mucosa in active ulcerative colitis appear to be partially degranulated, suggesting the release of tryptase. AIM: To investigate the safety and activity of APC 2059, a highly specific tryptase inhibitor, in the treatment of ulcerative colitis. METHODS: This was an open-label, Phase 2, multicentre pilot study in patients with mildly to moderately active ulcerative colitis, with a disease activity index of 6-9 on a 12-point scale. Fifty-six adults received 20 mg APC 2059 subcutaneously twice daily and 53 completed 28 days of treatment. The primary end-point was response, defined as a final disease activity index of < or = 3. Supplementary analyses were also performed. RESULTS: Sixteen (29%) of 56 patients responded. Five (9%) showed complete remission (disease activity index=0). Twenty-seven (49%) improved, with a final disease activity index of < or = 3 or a four-point reduction. Improvement or normalization in each category of the disease activity index was as follows: stool frequency, 64%; bleeding, 64%; endoscopy, 50%; physicians' rating, 63%. There were no significant relationships between outcome and pharmacokinetics. The most common adverse events were related to the injection site (32.1%). CONCLUSIONS: In this pilot study, the tryptase inhibitor APC 2059 was safe and there was evidence of activity in the treatment of ulcerative colitis.

Neural control of left ventricular contractility in the dog heart: synaptic interactions of negative inotropic vagal preganglionic neurons in the nucleus ambiguus with tyrosine hydroxylase immunoreactive terminals.

Recent physiological evidence indicates that vagal postganglionic control of left ventricular contractility is mediated by neurons found in a ventricular epicardial fat pad ganglion. In the dog this region has been referred to as the cranial medial ventricular (CMV) ganglion [J.L. Ardell, Structure and function of mammalian intrinsic cardiac neurons, in: J.A. Armour, J.L. Ardell (Eds.). Neurocardiology, Oxford Univ. Press, New York, 1994, pp. 95-114; B.X. Yuan, J.L. Ardell, D.A. Hopkins, A.M. Losier, J.A. Armour, Gross and microscopic anatomy of the canine intrinsic cardiac nervous system, Anat. Rec., 239 (1994) 75-87]. Since activation of the vagal neuronal input to the CMV ganglion reduces left ventricular contractility without influencing cardiac rate or AV conduction, this ganglion contains a functionally selective pool of negative inotropic parasympathetic postganglionic neurons. In the present report we have defined the light microscopic distribution of preganglionic negative inotropic neurons in the CNS which are retrogradely labeled from the CMV ganglion. Some tissues were also processed for the simultaneous immunocytochemical visualization of tyrosine hydroxylase (TH: a marker for catecholaminergic neurons) and examined with both light microscopic and electron microscopic methods. Histochemically visualized neurons were observed in a long slender column in the ventrolateral nucleus ambiguus (NA-VL). The greatest number of retrogradely labeled neurons were observed just rostral to the level of the area postrema. TH perikarya and dendrites were commonly observed interspersed with vagal motoneurons in the NA-VL. TH nerve terminals formed axo-dendritic synapses upon negative inotropic vagal motoneurons, however the origin of these terminals remains to be determined. We conclude that synaptic interactions exist which would permit the parasympathetic preganglionic vagal control of left ventricular contractility to be modulated monosynaptically by catecholaminergic afferents to the NA-VL.

Parasympathetic neurons in the cranial medial ventricular fat pad on the dog heart selectively decrease ventricular contractility.

We hypothesized that selective control of ventricular contractility might be mediated by postganglionic parasympathetic neurons in the cranial medial ventricular (CMV) ganglion plexus located in a fat pad at the base of the aorta. Sinus rate, atrioventricular (AV) conduction (ventricular rate during atrial pacing), and left ventricular contractile force (LV dP/dt during right ventricular pacing) were measured in eight chloralose-anesthetized dogs both before and during bilateral cervical vagus stimulation (20-30 V, 0.5 ms pulses, 15-20 Hz). Seven of these dogs were tested under beta-adrenergic blockade (propranolol, 0.8 mg kg(-1) i.v.). Control responses included sinus node bradycardia or arrest during spontaneous rhythm, high grade AV block or complete heart block, and a 30% decrease in contractility from 2118 +/- 186 to 1526 +/- 187 mm Hg s(-1) (P < 0.05). Next, the ganglionic blocker trimethaphan (0.3-1.0 ml of a 50 microg ml(-1) solution) was injected into the CMV fat pad. Then vagal stimulation was repeated, which now produced a relatively small 5% (N.S., P > 0.05) decrease in contractility but still elicited the same degree of sinus bradycardia and AV block (N = 8, P < 0.05). Five dogs were re-tested 3 h after trimethaphan fat pad injection, at which time blockade of vagally-induced negative inotropy was partially reversed, as vagal stimulation decreased LV dP/dt by 19%. The same dose of trimethaphan given either locally into other fat pads (PVFP or IVC-ILA) or systemically (i.v.) had no effect on vagally-induced negative inotropy. Thus, parasympathetic ganglia located in the CMV fat pad mediated a decrease in ventricular contractility during vagal stimulation. Blockade of the CMV fat pad had no effect on vagally-mediated slowing of sinus rate or AV conduction.

Negative regulation of Fc epsilon RI-mediated degranulation by CD81.

Signaling through the high affinity receptor for immunoglobulin E (Fc epsilon RI) results in the coordinate activation of tyrosine kinases before calcium mobilization. Receptors capable of interfering with the signaling of antigen receptors, such as Fc epsilon RI, recruit tyrosine and inositol phosphatases that results in diminished calcium mobilization. Here, we show that antibodies recognizing CD81 inhibit Fc epsilon RI-mediated mast cell degranulation but, surprisingly, without affecting aggregation-dependent tyrosine phosphorylation, calcium mobilization, or leukotriene synthesis. Furthermore, CD81 antibodies also inhibit mast cell degranulation in vivo as measured by reduced passive cutaneous anaphylaxis responses. These results reveal an unsuspected calcium-independent pathway of antigen receptor regulation, which is accessible to engagement by membrane proteins and on which novel therapeutic approaches to allergic diseases could be based.

Minimizing oral complications of cancer treatment.

Aggressive cancer therapy places patients at greater risk for oral complications and treatment-related consequences. Unfortunately, prevention and/or treatment of such oral sequelae have become often overlooked priorities of the treatment team. We describe a philosophy of management of the cancer patient that specifically emphasizes the prevention and treatment of oral complications associated with cancer therapy. These concepts and principles are based on treatment protocols and ongoing clinical practices at The University of Texas M. D. Anderson Cancer Center in Houston, Texas.

Fabrication and use of an intracavitary radiotherapeutic applicator for the posterior sinus wall: a case report.

The essential features of and the prosthodontic procedures necessary for fabricating a radiation applicator from dental acrylic resin for use in a clinical case of recurrent squamous cell carcinoma treated by intracavitary radiotherapy are described. A method for reducing radiation dose to the optic chiasm using Cerrobend alloy is presented.

Oral and dental management of the cancer patient: prevention and treatment of complications.

Aggressive cancer therapy places patients at greater risk for oral complications and treatment-related consequences. Unfortunately, prevention and/or treatment of such oral sequelae has become an often overlooked priority of the treatment team. We describe a philosophy of management of the cancer patient that specifically emphasizes the prevention and treatment of oral complications associated with cancer therapy. These concepts and principles are based on treatment protocols and ongoing clinical research at the University of Texas M.D. Anderson Cancer Center in Houston, Texas.

Cariogenic microflora in patients with Hodgkin's disease before and after mantle field radiotherapy.

Because mantle field radiotherapy is associated with partial xerostomia in patients with Hodgkin's disease, the purpose of this study was to evaluate their cariogenic microflora before and after completion of radiotherapy. We obtained samples of oral saline solution rinse from 40 patients with Hodgkin's disease before radiotherapy and from 31 patients with Hodgkin's disease who had survived 1 to 24 years after radiotherapy. We also evaluated caries experience and history of fluoride gel use for caries prevention in these patients. Mutans streptococci and lactobacilli levels were significantly higher in the postradiotherapy patients with carious teeth, particularly in those with limited home use of fluoride gels. In the postradiotherapy group, caries parameters were significantly higher (p < 0.05) than in the preradiotherapy group. Within the postradiotherapy group, both caries and microbial parameters tended to be higher in patients who were less compliant about using the recommended 0.4% stannous fluoride "brush-in" technique than in those who used the gel regularly at home. This study indicates that for patients with Hodgkin's disease who receive mantle field irradiation during the management of their disease, a sustained brush-in program with stannous fluoride gel can be of benefit for caries prevention and for limitation of oral levels of cariogenic mutans streptococci.

Multiple glycosylphosphatidylinositol-anchored Ly-6 molecules and transmembrane Ly-6E mediate inhibition of IL-2 production.

Cross-linking of Ly-6 molecules on T lymphocytes leads to IL-2 production, whereas costimulation of T cells via Ly-6A/E and the TCR inhibits IL-2 secretion. This study was initiated to determine whether there are unique structural requirements at the level of the Ly-6 molecule for its capacity to activate or block IL-2 production. Functional studies in which transfected EL-4J cells that expressed various Ly-6 proteins or chimeric Ly-6 molecules were used have demonstrated that direct activation of IL-2 secretion or inhibition of anti-CD3-induced IL-2 production occurred after mAb binding to Ly-6A/E, Ly-6C, and Ly-6G and was independent of whether the mAbs bound to amino- or carboxyl-terminal epitopes of Ly-6. The blockade of IL-2 production by costimulation with anti-CD3 and anti-Ly-6 was detected even when the addition of either mAb was temporally delayed for up to 17 h in a reciprocal fashion. Stimulation of mouse Ly-6 proteins expressed in Jurkat cells antagonized PMA/OKT3-induced IL-2 production, thus revealing that the Ly-6 inhibitory pathway is operative in human cells. EL-4J cells were also transfected with a chimeric construct in which the glycosylphosphatidylinositol anchor of Ly-6E was replaced by the transmembrane and a portion of the intracytoplasmic tail of H-2Db. Anti-Ly-6A/E also blocked anti-CD3-induced IL-2 production for these cells, although anti-Ly-6A/E failed to directly induce IL-2 secretion. Thus, anti-Ly-6A/E blockade of IL-2 production is independent of the glycosylphosphatidylinositol anchor of Ly-6E. This finding suggests that there may be aspects of signaling via Ly-6 that are solely dependent on the extracellular amino acid sequence of this protein.

Regulation of nuclear factor-kappa B and activator protein-1 activities after stimulation of T cells via glycosylphosphatidylinositol-anchored Ly-6A/E.

Cross-linking of glycosylphosphatidylinositol-anchored proteins, including mouse Ly-6A/E, leads to IL-2 secretion and T cell activation, whereas engagement of Ly-6A/E uniquely inhibits IL-2 production induced via TCR. However, little is known concerning the molecular mechanism by which glycosylphosphatidylinositol-anchored proteins regulate IL-2 expression. In this study, we have examined the ability of an anti-Ly-6A/E mAb to regulate transcription factors controlling IL-2 expression. Stimulation of EL4J(Ly-6E).A4 cells with anti-CD3 epsilon or anti-Ly6A/E mAbs induced nuclear factor (NF)-kappa B p65-p50 (RelA/p50) and AP-1 (Fos/Jun) binding activities and increased nuclear factor of activated T cells (NF-AT) activity, whereas octamer-binding factor and NF-Y levels were stable. Cyclic AMP response element binding protein and T cell-specific factor-1 (alpha) activities were selectively enhanced by anti-CD3 epsilon, but not by anti-Ly6A/E, which suggests that signaling via the TCR and Ly-6 were not identical. Costimulation of these cells with both mAbs produced substantially reduced levels of AP-1, NF-AT, and, especially, NF-kappa B p65-p50 whereas cyclic AMP response element binding protein and T cell-specific factor-1(alpha) were induced to a level seen after stimulation by anti-CD3 epsilon. The inducibility of the IL-2 enhancer in vivo and the contribution of individual transcription factors for this induction were assessed with use of reporter chloramphenicol acetyltransferase constructs containing the IL-2 enhancer or oligomerized binding sites for transcription factors. These experiments also demonstrated a key role for NF-kappa B and AP-1 in the transcriptional regulation of the IL-2 gene by TCR- and Ly6A/E-mediated signaling. By using the 2B4.11 T cell hybridoma and a mutated variant, were revealed a crucial role for the zeta-chain in Ly6A/E-mediated activation of NF-kappa B.

Regulation of T lymphocyte function by glycosylphosphatidylinositol (GPI)-anchored proteins.

Monoclonal antibody binding to GPI-anchored proteins, e.g. Thy-1 and Ly-6, on the surface of T lymphocytes usually leads to stimulation of interleukin-2 production. This phenomenon is dependent upon expression of the zeta-chain of the T cell receptor complex and requires the GPI anchor. Recent studies suggest that this activation may proceed through a common pathway resulting in tyrosine phosphorylation of intracellular substrates and association of various GPI-anchored proteins to src-family tyrosine kinases. Several models are discussed to explain the signaling capabilities of GPI-anchored proteins. In contrast, under some experimental conditions antibody binding to selected GPI-anchored proteins, i.e. Ly-6A/E and sgp60 (CD48), leads to inhibition of T cell activation. Furthermore, induction of Ly-6A/E expression on CD4 effector T cells correlates with a decreased capacity to secrete IL-2. These latter results suggest that Ly-6A/E may also function to down-regulate an immune response.

Selective expression of Ly-6G on myeloid lineage cells in mouse bone marrow. RB6-8C5 mAb to granulocyte-differentiation antigen (Gr-1) detects members of the Ly-6 family.

Mouse Ly-6 proteins are characterized by lineage-restricted patterns of expression on lymphoid cells. A mAb (1A8) was produced to Ly-6G, a newly described member of the Ly-6 locus. Based on selective reactivity to cloned Ly-6 gene products expressed in EL4J cells, 1A8 was determined to be specific for Ly-6G. Furthermore, mAb to other Ly-6 specificities did not bind to Ly-6G-transfected EL4J cells, indicating that Ly-6G is distinct from other serologically defined Ly-6 specificities. FACS analysis using 1A8 demonstrated that Ly-6G was expressed in bone marrow but not substantially on other lymphoid tissues, including activated T and B cells. In the bone marrow, Ly-6G expression was primarily restricted to the cells with more forward angle light scatter, which are mostly granulocytes. The RB6-8C5 mAb, previously described to detect a myeloid-restricted Ag (Gr-1) on more differentiated granulocytes, also reacted with Ly-6G- and Ly-6C-transfected EL4J cells. Both 1A8 and RB6-8C5 selectively precipitate a M(r) 21 to 25 kDa, glycosylphosphatidylinositol-anchored protein. Collectively, these data indicate that the Gr-1 Ag is a member of the Ly-6 family and further link expression of individual Ly-6 genes with distinct lineages in mouse bone marrow cells.

Characterization of two novel Ly-6 genes. Protein sequence and potential structural similarity to alpha-bungarotoxin and other neurotoxins.

Genomic clones cross-hybridizing with Ly-6A.2 cDNA were isolated and characterized for functional Ly-6-related genes. Two new Ly-6 genes, designated Ly-6F.1 and Ly-6G.1, were found to have high nucleotide homology (> or = 70%) and the characteristic four exon gene organization of Ly-6A/E and Ly-6C. By a PCR-based assay, Ly-6G.1 mRNA was readily found in bone marrow, whereas Ly-6F.1 mRNA was not detected in lymphoid tissues. Thus, Ly-6G.1 represents an additional Ly-6 gene with apparent selective expression in hematopoietic cells distinct from Ly-6A/E and Ly-6C. Using the available deduced protein sequence data for mature Ly-6 proteins, searches of the database uncovered an evolutionary relationship of Ly-6 proteins with neurotoxins isolated from snake venoms. The protein sequence conservation between the two groups was selective for, but not limited to, residues in neurotoxins that have been found to be important for their tertiary structures. From this relationship, we propose a neurotoxin-like structure for Ly-6 and Ly-6-related proteins, such as CD59.

Role of Ly-6A/E and T cell receptor-zeta for IL-2 production. Phosphatidylinositol-anchored Ly-6A/E antagonizes T cell receptor-mediated IL-2 production by a zeta-independent pathway.

Ly-6A/E molecules were originally implicated in regulation of T cell activation because anti-Ly-6A/E mAb induce IL-2 production. More recently we have shown that anti-Ly-6A/E also inhibits IL-2 production induced by anti-CD3. In the present study we used mutant and transfected cell lines that varied in expression of Ly-6A/E or TCR-zeta to test whether the positive and negative modulations of IL-2 production by anti-Ly-6A/E occur by distinct mechanisms. Anti-Ly-6A/E inhibited anti-CD3-induced IL-2 production for Ly-6E.1-transfected EL4J cells, but did not affect IL-2 production of the parental Ly-6A/E-negative EL4J cells. These results indicate that TCR-mediated IL-2 production can occur in the absence of Ly-6A/E expression and establish that anti-Ly-6A/E-induced inhibition of IL-2 production was the result of antibody binding to Ly-6A/E. As expected, MA5.8 (zeta-negative) or CT108 (zeta-truncated) variants of the 2B4.11 T cell hybridoma did not produce IL-2 when stimulated with anti-Thy-1 or anti-Ly-6A/E mAb. In contrast, anti-Ly-6A/E inhibited anti-CD3-induced IL-2 production by MA5.8 and CT108. Furthermore, anti-Ly-6A/E-induced IL-2 production was restored for zeta-transfected MA5.8. Thus, although induction of IL-2 by anti-Ly-6A/E depends on zeta expression, inhibition of IL-2 by anti-Ly-6A/E occurs by a zeta-independent mechanism. Interestingly, anti-Ly-6A/E, but not anti-Thy-1, inhibited anti-CD3-induced IL-2 production by MA5.8 and Ly-6E.1-transfected EL4J. Therefore, inhibition of IL-2 production by anti-Ly-6A/E was not a general property of a mAb binding to a phosphatidylinositol-linked molecule, as has been suggested for induction of IL-2 production. Taken together these data suggest that the molecular mechanisms of induction and inhibition of IL-2 production by anti-Ly-6A/E are separable and expression of TCR-zeta is one variable that distinguishes these two pathways.

Radiotherapeutic management of an orocutaneous defect with a balloon-retaining stent.

Maxillary resection defects have traditionally been technically difficult to treat with conventional radiation therapy. The irregular contours of the defect lead to an uneven distribution of the radiation doses. The potential to undertreat defects of microscopic involvement may leave residual disease. Tissue morbidity is high at isolated "hot spots" or at locations of excessive dose distribution. The use of a water-filled balloon bolus in conjunction with a balloon-retaining stent can significantly improve treatment efficacy and decrease tissue morbidity. This article describes a technique for the fabrication of a balloon-retaining stent for an orocutaneous defect.

Devices valuable in head and neck radiotherapy.

Normal tissue reactions limit the use of radiotherapy in the management of patients with head and neck neoplasms. Customized intraoral stents can help prevent unnecessary irradiation of various normal tissues thus reducing severity of reactions. Two basic types of devices, referred to as shielding and positional stents, are presented. The fabrication and the application of such devices are illustrated through five case reports. Recommendations on use of these tools and the possibility of combining these means with methods to improve dose distribution within the target volume containing air gaps are provided. Close collaboration between the attending radiotherapist and dentist is essential for designing appropriate devices for individual patients. However, when properly designed and used, these stents are effective in reducing treatment morbidity.

Salivary flow rates in patients with head and neck cancer 0.5 to 25 years after radiotherapy.

In this clinical study at the University of Texas M. D. Anderson Cancer Center, unstimulated and stimulated salivary flow rates were obtained from 47 patients with head and neck cancer who had received mantle, unilateral facial, or bilateral facial field radiotherapy from 0.5 to 25 years earlier. The magnitude of salivary flow rate reduction compared with a healthy control group was primarily related to the radiation dosage and the amount of salivary gland tissue included in the irradiated fields. Flow rates were lower for women in all groups, but these differences were not statistically significant.

Down-regulation of IL-2 production by activation of T cells through Ly-6A/E.

Ly-6A/E molecules are expressed on the surface of T cells and have been shown to function in activation by the capacity of anti-Ly-6A/E mAb to induce T cell hybridomas or normal T cells to produce IL-2. Recent evidence suggests that activation through Ly-6A/E may be linked to the TCR signaling pathway. To further investigate the relationship between Ly-6- and TCR-induced T cell activation, we have examined whether an anti-Ly-6A/E mAb (D7) modulates TCR signaling in vitro. We now report that mAb D7 specifically inhibited IL-2 production by T cells also activated through TCR. Such inhibition was noted for normal T cells stimulated by soluble anti-CD3 or alloantigen and for T hybridomas stimulated by soluble anti-CD3. The ability of D7 to inhibit IL-2 production by T hybridomas was dependent on the nature of the TCR activating signal because IL-2 production was not inhibited when T hybridomas were stimulated with Ag or immobilized anti-CD3. Inhibition of IL-2 production by D7 apparently required cross-linking of the mAb because D7 F(ab')2 fragments were not effective for inhibition of IL-2 production. Similar to its ability to enhance anti-Ly-6A/E-induced activation of T and B cells, IFN-gamma enhanced the D7-induced inhibition of IL-2 production by alloantigen-activated normal T cells. These data further support the notion that Ly-6 and TCR signaling pathways are interrelated.