The effect of investment material type on the contamination zone and mechanical properties of commercially pure titanium castings

STATEMENT OF PROBLEM: Different types of investment materials affect the formation of a surface contamination zone within commercially pure titanium (cpTi) castings. This contamination zone may possibly alter the mechanical properties of cast titanium, which may be problematic for castings used in the fabrication of removable and fixed prostheses. PURPOSE: The purpose of this study was to evaluate the effect of different types of investments on the extent of contamination zone and the modulus of elasticity, yield strength, elongation, and hardness of cpTi castings. MATERIAL AND METHODS: Forty wax patterns were fabricated according to ISO 9693 for tensile testing. The patterns were divided into 2 groups of 20 patterns each, invested, and cast in pairs using cpTi. The first group (P) was invested with a phosphate-bonded silica-based investment material (Ticoat S+L), and the second group (M), with a magnesia-alumina investment material (Rematitan Ultra). Investment materials were examined by x-ray diffraction analysis (XRD). One specimen from each group was sectioned and prepared for metallographic observation. The extent of the contamination zone was determined by scanning electron microscopy, using back-scattering electron imaging and energy dispersive spectroscopy analysis, as well as microhardness testing. The tensile strength of the specimens was determined in a universal testing machine. From the derived tensile curves, the modulus of elasticity, yield strength, and percentage elongation were calculated and statistically evaluated among the groups using the Student t test (alpha=.05). Three fractured specimens from each group were examined by scanning electron microscopy to determine the mode of fracture. RESULTS: XRD analysis showed that silica and magnesia were the dominant phases of Ticoat S+L and Rematitan Ultra, respectively. The contamination zone was found to extend 50 to 80 mum for the P specimens and 15 to 20 mum for the M specimens. No significance difference was found for the modulus of elasticity (P=85 +/- 11 GPa, M=79 +/- 13 GPa), whereas significant differences were found for the yield strength (P=462 +/- 48 MPa, M=321 +/- 54 MPa; P<.001) and percentage elongation (P=12 +/- 2, M=21 +/- 7; P=.002) between the groups tested. The fracture mode was brittle externally and ductile internally for both groups. CONCLUSIONS: According to the results of this study, the extent of the contamination zone as well as the yield strength and percentage elongation of the cpTi castings were significantly affected by the type of the investment material.     

Areal and laminar variations in the vascularity of the visual, auditory, and entorhinal cortices of the developing rat brain

Understanding of place-specific cortical cerebrovascular changes after insult and injury depends on the detailed knowledge of the areal and laminar variations in cortical vascularity. The present study examines comparatively the developmental changes of the total vascular density and the density of capillaries and medium- and large-sized vessels in the primary visual cortex (Oc1), the primary auditory cortex (Te1), and the lateral entorhinal cortex (EntL) of the developing rat brain. Vascular networks in the three cortical areas were marked after transcardial perfusion of India ink and quantified with an image analysis system. Parameters examined exhibited (i) peculiar developmental time course within individual cortical layers and (ii) area- and age-dependent variations. Angioarchitecture in Te1 layers was stabilized earlier than that in Oc1 layers and the period of postnatal development of the vascularity of neocortical sensory areas Oc1 and Te1 appeared to be more protracted compared to that of the phylogenetically older entorhinal cortex. By the end of the first postnatal month, vascular densities in the three cortical areas established a dorsoventral gradient (Oc1 > Te1 > EntL). Finally, in all areas, layer IV was the first layer to obtain adult values of capillary density.     

The prognostic inhomogeneity of colorectal carcinomas Stage III: a proposal for subdivision of Stage III.

BACKGROUND: The prognosis of patients with Stage III colorectal carcinoma seems to be inhomogeneous. Therefore a subdivision of Stage III was performed. METHODS: Data from 850 patients of the Erlangen Registry of Colo-Rectal Carcinomas and 603 patients of the Study Group Colo-Rectal Carcinoma (SGCRC) with Stage III colorectal carcinoma were analyzed. Three different subdivisions of Stage III were performed according to pT, pN, and pTpN. Observed 5-year survival rates for all possible substages were calculated according to Kaplan-Meier. To compare the predictive value of several possible substages, Brier-Score and receiver operator charcteristics (ROC) analysis were applied. RESULTS: The subdivision according to pT (pT1,2pN1,2 versus pT3 pN1,2 versus pT4 pN1,2) as well as the subdivision according to pN (any pT pN1 vs. any pT pN2) resulted in significant differences of observed 5-year survival rates. However, subdivision according to pT and pN (pT1,2 pN1 vs. pT3,4pN1 and pT1,2pN2 vs. pT3,4 pN2) was found to be superior. The three substages, IIIA, IIIB, and IIIC, identified 10%, 50%, and 40% of the patients with observed 5-year survival rates of 80%, 60%, and 30%, respectively. Using Brier-Score and ROC analysis an increase in predictive power was found, especially for the patients of the Erlangen Registry, but less clearly for SGCRC patients. CONCLUSION: Subdivision of Stage III colorectal carcinoma into three substages according to the pT and pN categories resulted in subgroups which differed significantly in prognosis. This may be important for comparing treatment results, especially in adjuvant treatment and patient care evaluation studies.     

Interferon-induced retinopathy in asymptomatic cancer patients

OBJECTIVES: Interferon-induced ocular complications, including retinal ischemia and ischemic optic neuropathy, can be associated with significant visual loss. We report three cases of asymptomatic ischemic retinopathy in cancer patients receiving interferon. DESIGN: Retrospective, interventional, noncomparative small case series. METHODS: Retrospective review of the medical records and fundus photographs. RESULTS: Interferon-induced ischemic retinopathy can occur in asymptomatic cancer patients. The retinal changes are usually reversible with discontinuation of interferon therapy. CONCLUSIONS: These three cases underscore the importance of dilated funduscopic examination at baseline and during follow-up, at least every 3 months, for all cancer patients receiving interferon to identify retinal toxicity at its earliest stages. A prospective study evaluating the incidence and severity of interferon retinopathy in cancer patients would be prudent.     

Distribution and synaptology of vasoactive intestinal polypeptide (VIP) immunoreactive structures in the rat periaqueductal grey

Light microscopic analysis of the rat midbrain periaqueductal grey (PAG) showed vasoactive intestinal polypeptide immunoreactive (VIP-ir) neurons localized at the lateral and ventral walls of the aqueduct. Some varicose VIP-ir elements were detected closely associated with the ependyma. While several VIP-ir elements were encountered immediately under the ependyma, in a few cases, VIP-ir cell bodies were seen on the luminal surface of the ependymal cells lining the aqueduct. Electron microscopy revealed that most of these cells possessed the characteristics of a local circuit neuron. All VIP-ir cells had indented nuclei. Two types were distinguished: one with rounded cell body receiving numerous axo-somatic synapses established by VIP-negative axons. The other cell type was fusiform and its surface was almost fully isolated from axonal contacts by a glial sheath. The VIP-ir processes were interconnected with other periaqueductal cells by a variety of synaptic contacts. VIP-ir axon terminals formed asymmetric synapses with immunonegative dendritic shafts often in glomerulus-like assemblies. The postsynaptic immunonegative dendrites were of the aspinous, beaded type. We suggest that VIP-ir cells and processes in the midbrain PAG establish connections between the longitudinal functional columns of this region. On the basis of their morphology, VIP-ir cells in the PAG appear to be excitatory, terminating on inhibitory interneurons. Thus, a VIP-stimulated inhibition may be instrumental in the coordination of responses evoked by the stimulation of PAG columns.     

Cardiac Troponin I in Fulminant Adenovirus Myocarditis Treated with a 24-Hour Infusion of High-Dose Intravenous Immunoglobulin

We report a successful outcome on an acute adenovirus myocarditis treated with a 24-hour high-dose intravenous immunoglobulin (24-HDIVIG) in a 4.5-year-old girl. A postviral etiology of acute myocarditis was assessed on the basis of the polymerase chain reaction technique. Among other early markers of cardiac injury, cardiac isoform of troponin-I (cTnI) was significantly correlated to the left ventricular ejection fraction (r=−0.86, p < 0.0001). Follow-up of cTnI, which might also be correlated to the short-term outcome, allows fast, easy, and noninvasive estimation of response to the aggressive treatment with 24-HDIVIG in acute adenovirus myocarditis in children.     

Craniofacial fibrous dysplasia complicated by acute, reversible visual loss: report of two cases

We report two cases of craniofacial fibrous dysplasia which presented with acute visual loss. The first patient had a sphenoid sinus mucocele compressing the optic chiasm. In the second patient the optic canal was narrowed by dysplastic bone. In both cases optic nerve decompression restored vision to normal.     

Postoperative prognosis of pulmonary adenocarcinoma subtypes correlates with HLA-DR expression and the number of tumor-infiltrating cells

Human pulmonary adenocarcinomas (AC) can be divided into two types with special morphologic and immunohistologic properties and a different number of tumor-infiltrating cells as shown by previous investigations. In the present study the relevance of this subdivision for patients' survival was investigated. 42 surgically resected pulmonary AC of stage I and II were subclassified using light and electron microscope. For immunohistologic phenotypization, reactions with monoclonal antibodies against HLA-DR, CD1 and CD3 were studied on fresh tumor specimens. Postoperative survival was evaluated after at least 24 months. AC of type I (N=23) with mucin production and ultrastructural properties of goblet cells showed almost no HLA-DR expression. Infiltration by CD1-positive dendritic cells Langerhans cells and CD3-positive T lymphocytes was significantly lower than in AC of type II (N=19), which expressed HLA-DR homogeneously and showed, ultrastructurally, Clara cell and/or type II pneumocyte properties. Patients' outcome was similar in stage I AC of both types: about 70% of patients were still alive after 24 months. However, significant differences were found between the two types in stage II AC with regional lymph node metastases: survival of patients with AC of type II corresponded roughly with stage I tumors (67%) but only 20% of patients with type I AC were still alive after 24 months. These results indicate that postoperative prognosis for patients with pulmonary AC of type II is more favourable than for mucinous AC of type I. This may be due to the homogeneous HLA-DR expression and higher number of immunologically competent tumor-infiltrating cells which possibly results in better tumor surveillance.