TEM-EDX study of mechanism of bonelike apatite formation on bioactive titanium metal in simulated body fluid

Bioactive titanium metal, which forms a bonelike apatite layer on its surface in the body and bonds to the bone through the apatite layer, can be prepared by NaOH and heat treatments to form an amorphous sodium titanate layer on the metal. In the present study, the mechanism of apatite formation on the bioactive titanium metal has been investigated in vitro. The metal surface was examined using transmission electron microscopy and energy dispersive X-ray spectrometry as a function of the soaking time in a simulated body fluid (SBF) and complemented with atomic emission spectroscopy analysis of the fluid. It was found that, immediately after immersion in the SBF, the metal exchanged Na(+) ions from the surface sodium titanate with H(3)O(+) ions in the fluid to form Ti-OH groups on its surface. The Ti-OH groups, immediately after they were formed, incorporated the calcium ions in the fluid to form an amorphous calcium titanate. After a long soaking time, the amorphous calcium titanate incorporated the phosphate ions in the fluid to form an amorphous calcium phosphate with a low Ca/P atomic ratio of 1.40. The amorphous calcium phosphate thereafter converted into bonelike crystalline apatite with a Ca/P ratio of 1.65, which is equal to the value of bone mineral. The initial formation of the amorphous calcium titanate is proposed to be a consequence of the electrostatic interaction of negatively charged units of titania, which are dissociated from the Ti-OH groups, with the positively charged calcium ions in the fluid. The amorphous calcium titanate is speculated to gain a positive charge and to interact with the negatively charged phosphate ions in the fluid to form the amorphous calcium phosphate, which eventually stabilizes into bonelike crystalline apatite.     

Defects in the differentiation and function of bone marrow-derived dendritic cells in non-obese diabetic mice

Due to their high immunostimulatory ability as well as the critical role they play in the maintenance of self-tolerance, dendritic cells have been implicated in the pathogenesis of autoimmune diseases. The non-obese diabetic (NOD) mouse is an animal model of autoimmune type 1 diabetes, in which pancreatic beta cells are selectively destroyed mainly by T cell-mediated immune responses. To elucidate initiation mechanisms of beta cell-specific autoimmunity, we attempted to generate bone marrow-derived dendritic cells from NOD mice. However, our results showed low proliferative response of NOD bone marrow cells and some defects in the differentiation into the myeloid dendritic cells. NOD dendritic cells showed lower expressions of MHC class II, B7-1, B7-2 and CD40, compared with C57BL/6 dendritic cells. In mixed lymphocyte reactions, stimulatory activities of NOD dendritic cells were also weak. Treatment with LPS, INF-gamma and anti-CD40 stimulated NOD dendritic cells to produce IL-12p70. The amount of IL-12, however, appeared to be lower than that of C57BL/6. Results of the present study indicated that there may be some defects in the development of NOD dendritic cells in the bone marrow, which might have an impact on the breakdown of self tolerance.     

Sodium channels in ocular epithelia

Voltage-gated, tetrodotoxin(TTX)-blockable sodium channels are found in most excitable cells and are the primary contributors to action potentials generated by many of these cells. To date, there has only been one report of a non-cultured vertebrate epithelial cell type containing TTX-blockable Na⁺ channels: rabbit non-pigmented ciliary body epithelial cells [Cilluffo MC et al. (1991) Invest Opthalmol Vis Sci 32:1619–1629], and three reports of cultured epithelial cells containing TTX-blockable Na⁺ channels: rabbit non-pigmented and pigmented ciliary body epithelium [Ciluffo MC et al. (1991) Invest Opthalmol Vis Sci 32:1619–1629; Fain GL, Farahbakhsh (1989) J Physiol (Lond) 417:83–103] and human lens epithelium [Cooper K et al. (1990) J Membr Biol 117:285–298]. We report here the presence of sodium currents in two different non-cultured, freshly dissociated transporting epithelial cell types: the rabbit corneal endothelium and the frog lens epithelium. We also report the occurrence of sodium currents in six additional cultured ocular epithelial cell types from three different species. These currents have a current/voltage (I/V) relationship consistent with traditional voltage-gated Na⁺ currents, are quinidine- and TTX-blockable (of the low-affinity TTX-sensitive type), and disappear following bath substitution of Na⁺ with Cs⁺ or K⁺.     

Macromolecular release from collagen monolithic devices

Collagen monolithic devices varying in crosslinking density, collagen structure, and crosslinker were fabricated. In vitro release rates of a model macromolecule, inulin, were found to be linear with t1/2 and were affected by crosslinking density, nature of crosslinker, and collagen structure. The biodegradation of the collagen matrix was also examined. Proteolytic enzymes did not degrade the collagen devices; the degradation rate with collagenase was dependent on collagen structure, crosslinker, crosslinking density, and enzyme concentration. In vivo biocompatibility, degradation, and 14C-inulin release rates were evaluated subcutaneously in rats. After 3 weeks, none of the collagen discs induced any severe cellular response. Dacron induced a stronger fibroblast response but fewer inflammatory cells as compared to the collagen discs. No significant degradation of the collagen discs occurred within 3 weeks. In vivo release of 14C-inulin from collagen monolithic devices was diffusion controlled.     

Monophosphoryl lipid A (MPL) upregulates major histocompatibility complex (MHC) class I expression by increasing interferon-gamma (IFN-gamma)

Tumor immunity is primarily mediated by cells as CD8+ cytotoxic T lymphocytes (CTL) recognize tumor antigen by MHC class I molecules. But most tumors are associated with a decreased expression of MHC class I to escape the antitumor immunity of the host. Our previous data have demonstrated that MPL has an antitumor effect on metastatic lung cancer of B16 melanoma with enhancing cytotoxicity due to increase of IFN-gamma and IL-2, and decrease of IL-4, which indicates the stimulation of type 1 helper T cells (Th1). To determine the effects of MPL, IFN-gamma, TNF-alpha, and IL-1 alpha on MHC class I expression of B16 melanoma cells, we evaluated the expression of MHC class I molecules with treatments of MPL, IFN-gamma, TNF-alpha, and IL-1 alpha by flow cytometry. The supernatant of MPL-treated spleen cells in vitro upregulated the expression of MHC class I molecules of B16 melanoma cells compared to the control supernatant of spleen cells. The MHC class I expression of B16 melanoma cells treated with IFN-gamma, but not TNF-alpha or IL-1 alpha, increased in a time-dependent manner. In conclusion, MPL upregulated MHC class I expression of B16 melanoma cells by activating spleen cells via IFN-gamma. These data suggest that increased IFN-gamma by MPL is responsible for the upregulation of MHC class I expression to augment cytotoxicity. Therefore, we suggest that MPL could play an important role in immunotherapy.     

Quadricuspid aortic valve and single coronary ostium

We describe an autopsy patient in whom a rare congenital anomaly of quadricuspid semilunar aortic valve and coronary arteries originating from a single orifice of one aortic sinus occurred. To the best of our knowledge, this combination of cardiac anomalies has not been reported.     

Development of counterpulsation algorithm for a moving-actuator type pulsatile LVAD

A pulsatile left ventricular assist device (LVAD) was used to support the aortic blood pumping function of an injured left ventricle, and as a result helped its recovery. It is important to observe a left ventricle's pumping status and to adjust the operating status of a LVAD to reduce the left ventricle's pumping load and thus to enhance its recovery. To observe the left ventricle's pumping status, an electrocardiogram (ECG) signal is generally used because it is a result of the natural heart's blood pumping function. In this paper, we describe the development of an ECG based counterpulsation control algorithm that prevents simultaneous aortic blood co-pumping by a left ventricle and a moving-actuator type pulsatile LVAD and as a result, reduces the natural heart's pumping load. In addition, to verify the algorithm's applicability for LVAD control we designed three ECG based automatic pump control algorithms that use a developed counterpulsation control algorithm. These algorithms control the operating status of a LVAD automatically and, at the same time, maintain a counterpulsing status. The results of in vitro experiments show that the counterpulsing effect between a left ventricle and a LVAD was successfully produced and that the newly designed automatic pump control algorithms met their own control purposes with a counterpulsing effect.     

Acculturation and cigarette smoking among Korean American men

This study examined the prevalence and correlated factors of cigarette smoking in a cross-sectional, epidemiological survey of Korean American men living in Maryland (n=333). In this sample, 26.1% were current smokers and 42.3% were former smokers. The older age group (> or = 40 years) was more likely to have quit smoking than the younger age group (< 40 years). In multiple logistic regression analysis, acculturation was associated with smoking status; those who stayed more than 20 years in the U.S. were less likely to be current smokers (OR=0.32, 95% CI 0.13-0.77) than those who stayed less than 10 years. Alcohol use was associated with smoking status; those who consumed alcohol were more likely to be current smokers (OR=5.24, 95% CI 2.33-11.79) or former smokers (OR=5.45, 95% CI=2.69-11.04) than those did not. Those with hypertension were more likely to have quit smoking (OR=3.11, 95% CI=1.33-7.24). The results suggest that the role of acculturation in smoking status among Korean American men deserves further attention by researchers as well as by health professionals who develop smoking prevention and cessation programs.     

Sonographic findings of breast hamartoma: emphasis on compressibility

The characteristic features of hamartoma in terms of discrepancies in mammographic and sonographic shapes of the mass were evaluated. We reviewed 16 pathologically proven breast hamartomas, which had undergone preoperative mammography and ultrasonography. All masses were analyzed according to ACR-BIRADS on mammography. On sonography, each mass was analyzed for size, shape, margin, internal echogenicity, and posterior acoustic enhancement. We also analyzed the echogenicity of halo, and compared the characteristic changes in the shape of hamartomas attributable to compression in mammograms and sonograms. The most common sites were at 12 o'clock in the right breast and 2 o'clock in the left. The most common mammographic findings of the hamartomas were a round shape (11/16), a circumscribed margin (13/16), internal fat densities (D4)(16/16) and radiolucent halos (14/16). The most common sonographic findings of the hamartomas were an oval shape (16/16), circumscribed margins (10/16), heterogeneous internal echogenicity (14/16), echogenic (7/16) or echolucent halos (5/16), and posterior enhancements (12/16). The characteristic feature of hamartomas was a change of the mammographic round shape mass into an elongated oval shape mass by sonography (11/11), suggesting the compressibility of hamartomas. Three of the hamartomas contained a pathologically proven internal calcification. The presence of a hamartoma was suggested by a change in a mammographic round mass with a radiolucent halo into an oval heterogeneous mass surrounded by an echogenic or echolucent halo on the sonogram. This characteristic difference between the mammographic and sonographic findings was attributed to the hamartoma compressibility, and was associated with the over-proliferation of fat containing mature normal breast tissue.     

In vivo efficacy of bone-marrow-coated polycaprolactone scaffolds for the reconstruction of orbital defects in the pig

Alloplastic materials offer a number of advantages over bone autografts in the reconstruction of craniofacial defects. These include: lack of donor site morbidity, unlimited quantities of available material, and the possibility to conform exactly to the defect. An ideal bioresorbable material would degrade slowly, and have osteoconductive properties to allow replacement and remodeling by osseous tissue. This is seldom observed, the materials instead being replaced by fibrous tissue. Polycaprolactone (PCL), an FDA-approved bioresorbable polymer, has several properties that might make it suitable for reconstruction of craniofacial defects. The technique of fused deposition modeling (FDM) allows for the fabrication of highly reproducible bioresorbable 3D scaffolds. The nature of the fully interconnected pore network might enhance vascular ingrowth and osteoconductive properties. It was hypothesized that coating the scaffolds in bone marrow might enhance bone formation due to the osteoinductive nature of the bone-marrow mesenchymal cells. This study aimed to test these hypotheses in the pig model. Defects measuring 2 x 2 cm were surgically created in each orbit of eight Yorkshire pigs. The orbits were divided into three groups: Group 1 (n=4), no reconstruction (control); Group 2 (n=6), reconstruction with no coated PCL scaffolds; and Group 3 (n=6) reconstruction with bone-marrow-coated PCL scaffolds. The results were evaluated at 3 months by histological and histomorphometric analyses. The defects in Group 1 were covered with fibrous scar tissue. The shape of the reconstructed area was insufficient. The defects in Groups 2 and 3 were reconstructed correctly. In Group 2 the noncoated scaffolds showed 4.5% of new bone formation compared with 14.1% in Group 3, which is statistically significant (p<0.05). The entirely interconnected 3D polycaprolactone scaffold seems to be a promising material. It induces the bone ingrowth required for reconstructing craniofacial and orbital defects. Further long-term evaluations of these PCL scaffolds must be made in order to confirm these conclusions.