Real-time terahertz near-field microscope.

We report a terahertz near-field microscope with a high dynamic range that can capture images of a 370 x 740 µm2 area at 35 frames per second. We achieve high spatial resolution (14 µm corresponding to λ/30 for a center frequency at 0.7 THz) on a large area by combining two novel techniques: terahertz generation by tilted-pulse-front excitation and electro-optic balanced imaging detection using a thin crystal. To demonstrate the microscope capability, we reveal the field enhancement at the gap position of a dipole antenna after the irradiation of a terahertz pulse.

Antibodies against domain E3 of laminin-1 and integrin alpha 6 subunit perturb branching epithelial morphogenesis of submandibular gland, but by different modes.

Branching epithelial morphogenesis requires interactions between the surrounding mesenchyme and the epithelium, as well as interactions between basement membrane components and the epithelium. Embryonic submandibular gland was used to study the roles of two mesenchymal proteins, epimorphin and tenascin-C, as well as the epithelial protein laminin-1 and one of its integrin receptors on branching morphogenesis. Laminin-1 is a heterotrimer composed of an alpha 1 chain and two smaller chains (beta 1 and gamma 1). Immunofluorescence revealed a transient expression of laminin alpha 1 chain in the epithelial basement membrane during early stages of branching morphogenesis. Other laminin-1 chains and alpha 6, beta 1, and beta 4 integrin subunits seemed to be expressed constitutively. Expression of epimorphin, but not tenascin-C, was seen in the mesenchyme during early developmental stages, but a mAb against epimorphin did not perturb branching morphogenesis of this early epithelium. In contrast, inhibition of branching morphogenesis was seen with a mAb against the carboxy terminus of laminin alpha 1 chain, the E3 domain. An inhibition of branching was also seen with a mAb against the integrin alpha 6 subunit. The antibodies against laminin alpha 1 chain and integrin alpha 6 subunit perturbed development in distinct fashions. Whereas treatment with the anti-E3 resulted in discontinuities of the basement membrane at the tips of the branching epithelium, treatment with the mAb against alpha 6 integrin subunit seemed to leave the basement membrane intact. We suggest that the laminin E3 domain is involved in basement membrane formation, whereas alpha 6 beta 1 integrin binding to laminin-1 may elicit differentiation signals to the epithelial cells.

How does higher ultrafiltration within the conventional clinical range impact the volume status of hemodialysis patients?

AIMS: The higher ultrafiltration (UF) induces poor outcomes. The impact of higher UF on the volume status was investigated. METHODS: 60 hemodialysis (HD) patients were divided into three groups according to the ratio of total UF to post-dialysis body weight (TUF/PDW) (<3%, 3-5%, > or =5%). ANP, the ratio of extracellular water to total body water and excess fluid mass (ExF/PDW) by bioimpedance spectroscopy, inferior vena cava diameter by ultrasound were measured at the end of HD. The ratio of post-HD blood volume to pre-HD (BVpost/BVpre) and standardized filtration coefficients (Lpst) of the microvasculature in the vicinity of PDW were calculated. RESULTS: Only Lpst and BVpost/BVpre showed significant differences among the three groups. A stepwise multiple linear regression model revealed that BVpost/BVpre was correlated with TUF/PDW, ExF/PDW and Lpst (R = 0.778, p < 0.001), independently. CONCLUSION: Higher UF causes decreases in BVpost/BVpre and Lpst. BVpost/BVpre was determined by TUF/PDW, ExF/PDW and Lpst.

Terahertz conductivity of localized photoinduced carriers in a Mott insulator YTiO(3) at low excitation density, contrasted with the metallic nature in a band semiconductor Si.

We performed optical-pump terahertz-probe measurements of a Mott insulator YTiO(3) and a band semiconductor Si using a laser diode (1.47 eV) and a femtosecond-pulse laser (1.55 eV). Both samples possess long energy-relaxation times (1.5 ms for YTiO(3) and 15 µs for Si); therefore, it is possible to extract terahertz complex conductivities of photoinduced carriers under equilibrium. We observed highly contrasting behaviour-Drude conductivity in Si and localized conductivity possibly obeying the Jonscher law in YTiO(3). The carrier number at the highest carrier-concentration layer in YTiO(3) is estimated to be 0.015 per Ti site. Anisotropic conductivity of YTiO(3) is determined. Our study indicates that localized carriers might play an important role in the incipient formation of photoinduced metallic phases in Mott insulators. In addition, this study shows that the transfer-matrix method is effective for extracting an optical constant of a sample with a spatially inhomogeneous carrier distribution.

Usefulness of an accelerometer-based portable navigation system in total knee arthroplasty.

AIMS: The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss. PATIENTS AND METHODS: A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group). RESULTS: One patient (0.8%) in the KA2 group and 19 in the IM group had an alignment which was > 3° away from the neutral mechanical axis (p < 0.01). The mean deviation from neutral alignment was 1.01° (standard deviation (sd) 1.0°) in the KA2 group and 1.93° (sd 1.7°) in the IM group (p < 0.01). Blood loss was significantly less in the KA2 group compared with the IM group (784 ml (sd 357) versus 1071 ml (sd 310), p < 0.001). CONCLUSION: The KneeAlign2 system provides a technically straightforward method for identifying the femoral head and performing an accurate distal femoral resection at TKA with significantly less blood loss compared with a conventional intramedullary guide. Cite this article: Bone Joint J 2017;99-B:1047-52.

Evaluation of the flexion gap by axial radiography of the distal femur.

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6 degrees (1.5 degrees to 6.3 degrees) compared with that obtained by MRI of 5.1 degrees (2.6 degrees to 9.5 degrees), a mean discrepancy of 1.49 degrees. The results obtained by radiography and MRI showed a strong correlation (r = 0.78). Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty.

Overexpression of cdk4/cyclin D1 induces apoptosis in PC12 cells in the presence of trophic support.

The induction of apoptosis by cell cycle regulator molecules under conditions optimal for exponential growth was examined in rat pheochromocytoma PC12 cells by overexpression of cyclins and cyclin-dependent kinases (cdks). By flow cytometry and by immunofluorescence, only cells overexpressing cdk4 or cyclin D1 underwent apoptosis, which was not associated with G1-arrest. Cdk4 kinase activity was significantly higher in cdk4-, or cyclin D1-expressing cells. Furthermore, induction of apoptosis by cdk4 was abrogated by co-transfection of p16(INK4), or dominant negative cdk4. These results suggest that upregulation of cdk4 kinase activity is a primary and critical mediator of apoptosis in PC12 cells under physiological conditions.

Distribution of alpha 6 integrin subunit in developing mouse submandibular gland.

We examined the development of mouse submandibular gland by light and electron microscopy and determined the distribution of the alpha 6 integrin subunit and laminin in this process by immunofluorescence and immunoelectron microscopy. At Days 13.5 and 14 of gestation alpha 6 was localized over the entire cell surface of undifferentiated epithelial cells of the terminal cluster. On Day 15 the expression of alpha 6 could no longer be detected over central cells in the proximal portion of branched terminal cluster, whereas peripheral cells were stained over the entire surface. On Day 17 of gestation to day of birth, alpha 6 expression was restricted to the basolateral surface of the differentiated acinotubular structure. Its expression on acinar cells was uniformly distributed throughout the basolateral membrane, but on duct cells stronger staining towards the basal surface was noted. Similar expression was observed in adult acinar and duct cells. Expression of the alpha 6-subunit at the cell-cell contact in an early stage and its expression at the basolateral surface in an advanced stage indicate that integrin containing alpha 6 plays a significant role in cell-cell and cell-substrate interaction. Stage and cell type-specific change of integrin expression may be significant for submandibular development.

Intracellular accumulation of basement membrane components during morphogenesis of rat submandibular gland.

The distribution of two basement membrane (BM) components, laminin (LN) and type IV collagen (COLL IV), during acino-tubular morphogenesis of rat submandibular gland was examined immunohistochemically to determine the role of BM in the development of acino-tubular structures. On day 14 of gestation, LN could be found only in the BM separating an undifferentiated cell cluster of gland epithelium from surrounding mesenchyme. However, during a short period through days 15 to 17, LN was detected not only in the BM but also in intracellular vesicles of the cells of the terminal cluster. Immunoelectron microscopy showed the intracellular immunoreactive sites to be rough endoplasmic reticulum, indicating that active LN synthesis occurs in the cells of the terminal cluster. Intracellular immunostaining of LN disappeared completely on day 19 with the development of simple epithelium from the cell cluster, even though BM remained reactive. COLL IV also was accumulated in the intracellular vesicles of terminal cluster cells on day 16 of gestation but not on day 19. These results indicate that synthesis of certain BM components is transiently stimulated in gland epithelium before the formation of simple epithelial structure, and that these components are significantly involved in morphogenesis of the submandibular gland.

Expression of epidermal growth factor receptor in fetal mouse submandibular gland detected by a biotinyltyramide-based catalyzed signal amplification method.

Branching morphogenesis of the fetal mouse submandibular gland (SMG) can be modulated in vitro by stimulation or inhibition of the epidermal growth factor receptor (EGFR). Because the mRNAs for EGF and EGFR are detectable in RNA of SMG rudiments isolated directly from fetuses, the EGF system probably operates physiologically as a regulator of SMG morphogenesis. However, neither EGFR protein nor its precise cellular localization has been characterized in the fetal SMG. Here we show EGFR protein in fetal mouse SMG by immunoprecipitation, affinity labeling, ligand-induced autophosphorylation, and immunohistochemistry. SMGs from E16 fetuses (day of vaginal plug = E0) were labeled with [35S]-cysteine/methionine and homogenized. After addition of specific antibody to EGFR, the immunoprecipitate was isolated, resolved by polyacrylamide gel electrophoresis, and detected by autoradiography. A single band of 170 kD was detected, corresponding to the EGFR protein. Affinity labeling with [125I]-EGF of the membrane fraction of E18 SMG also revealed a prominent band at 170 kD, showing that this EGFR protein can bind specifically to its ligand. Incubation of SMG membranes from E18 fetuses with EGF in the presence of [gamma-32P]-ATP, followed by immunoprecipitation with anti-phosphotyrosine antibody also showed a single band at 170 kD, demonstrating autophosphorylation of the EGFR in response to binding of its ligand. Immunohistochemical localization of the cellular sites of EGFR in the fetal SMG required use of a catalyzed signal amplification procedure, with biotinyltyramide as the amplifying agent. EGFR was localized predominantly, if not exclusively, in cell membranes of epithelial cells of the rudiment, whereas staining of mesenchymal cells was equivocal. Staining was strongest on duct cells, and weak on cells of the end-pieces. These findings clearly show that a functional EGFR protein is expressed in fetal SMG chiefly, if not exclusively, on epithelial cells.

Assessment of the role of GM-CSF in the cellular transformation and the development of erosive lesions around orthopaedic implants.

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a hematopoietic growth factor with a regulatory effect on the transformation of immature macrophages into multinucleated giant cells (MNGC) that exhibit phenotypic and functional characteristics of osteoclasts (OC). The authors analyzed the bone implant interface membranes harvested from 15 patients with failed total joint replacements for the production and tissue distribution of GM-CSF and interleukin-1 (IL-1). Immunohistology and liquid culture were employed to assess the contribution of these factors in the recruitment of macrophages and the development of bone resorbing MNGC at these sites. This process has been implicated in osteoclastic bone resorption, bone, and bone marrow necrosis adjacent to orthopaedic implants. Histologic assessment of the interface indicated the presence of granuloma and a variable number of MNGC in 11 cases. Four cases showed sites of intramembranous formation of osteoid and mineralized bone that was accompanied by normal bone marrow in two cases. Granulocyte-macrophage colony stimulating factor was expressed by a distinct subset of phagocytic macrophages in the lining layer on the implant side. interleukin-1-positive cells outnumbered those stained for GM-CSF. Stimulation of cultured cells with prosthetic metal particulate material showed marked similarity in the expression of these cytokines to cultures treated with lipopolysaccharide (LPS) or phytohemagglutinin (PHA). The induction of GM-CSF production in the lining layer where small MNGC develop indicates that these cells differentiate locally following the phagocytosis of particulate wear debris. In conclusion, GM-CSF promotes the proliferation and early stages of fusion and development of MNGC responsible for osteolysis at these sites. These results also highlight the capacity of the interface to display both osteogenic and inflammatory characteristics. Collectively, the findings suggest that the local bone marrow could participate in the development of the interface as a source of myeloid cells in addition to the capacity of marrow stroma to generate various osteogenic cells essential for the ingrowth of bone into prosthetic implants.

Bone formation and bone resorption in failed total joint arthroplasties: histomorphometric analysis with histochemical and immunohistochemical technique.

To elucidate the reactions of bone around aseptically loosened total joint arthroplasties, 24 interface tissues with adjacent bone were obtained in 17 revision operations (11 hips and six knees). The morphology of the bone surface next to the interface membrane was investigated with histochemical and immunohistochemical techniques and then histomorphometrically analysed. One-third of the total bone surface. 32.69 +/- 5.16% (mean +/- SE) (n = 24), showed positive alkaline phosphatase activity. The bone surface in contact with the cells positive for CD11b (a macrophage marker) amounted to 19.33 +/- 5.16% (n = 24). The proportion of the osteoclastic bone resorption estimated by vitronectin receptor expression was 7.67 +/- 1.82% (n = 21). Tissues retrieved from the sites where radiographic evidence of osteolysis was present (n = 12) had a significantly larger extent of the bone surface in contact with CD11b-positive cells than did the tissues from areas without osteolysis (n = 12, p = 0.0067, Mann-Whitney U test), whereas no significant difference was observed in the extent of osteoclastic bone resorption. These data demonstrate that active bone formation, regarded as a repair process, is the most common feature even in revised cases. They also highlight the role played by macrophages, not as cells producing inflammatory mediators that could activate osteoclasts, but as cells primarily responsible for the bone loss in osteolytic lesions.

Kinematics of the patella in deep flexion. Analysis with magnetic resonance imaging.

BACKGROUND: Little information is available on the kinematics of the normal knee in deep flexion. The purpose of this study was to use magnetic resonance imaging to analyze the patellofemoral articulation in deep flexion. METHODS: Axial scans were made of the patellofemoral joint of twenty healthy Japanese volunteers with the knee in approximately 90 degrees of flexion, in maximum active flexion (mean [and standard deviation], 140 degrees +/- 10 degrees ), and in maximum passive flexion (mean, 156 degrees +/- 5 degrees ). A fat-suppressed, three-dimensional, fast low-angle shot sequence was used to visualize the articular cartilage. The patellofemoral contact area was determined on sequential images and was reconstructed three-dimensionally. RESULTS: At 90 degrees of flexion, the contact area on the patella was continuous over the medial and lateral facets in fourteen knees and was located in the proximal half of the articular surface. At maximum active and passive flexion, the odd facet engaged in fifteen and eighteen knees, respectively. At maximum passive flexion, the contact area of the lateral facet moved distally and decreased significantly (p = 0.0002). From 90 degrees of flexion to maximum active flexion, the mean total contact area remained constant (3.43 +/- 0.70 and 3.62 +/- 0.72 cm (2), respectively); it then decreased significantly in maximum passive flexion (2.96 +/- 0.78 cm (2), p = 0.04). CONCLUSIONS: The contact area on the patella was divided into two parts (the odd and lateral facets) and moved distally in deep knee flexion. The size of the contact area on the lateral facet significantly decreased in maximum passive flexion.

Constituents and pH changes in protein rich hyaluronan solution affect the biotribological properties of artificial articular joints.

The relationship between the coefficient of friction and pH value or protein constituents of lubricating fluid, together with viscosity, were studied within a bearing surface model for artificial joint, ultra-high molecular weight polyethylene (UHMWPE) against stainless steel (SUS), using a mechanical spectrometer. Four lubricants were tested in this study: sodium hyaluronate (HA), HA with albumin, HA with gamma-globulin, and HA with (L)alpha-dipalmitoyl phosphatidylcholine ((L)alpha-DPPC). The coefficient of friction between UHMWPE and SUS in HA with albumin or HA with gamma-globulin varied from 0.035 to 0.070 depending on angular velocity and pH. The coefficient of friction in HA or HA with (L)alpha-DPPC varied from 0.023 to 0.045 depending on angular velocity and pH. The variation in pH for HA with albumin had a large effect on the coefficient of friction at low range of angular velocity with viscosity independence. The variation in pH for HA with gamma-globulin had a large effect on the coefficient of friction with viscosity dependence at high angular velocity. The addition of (L)alpha-DPPC showed a small effect on the coefficient of friction at low angular velocity. This study confirms that the presence of albumin in the lubricant promotes pH dependence and viscosity independence of the tribological properties at low speed while the presence of globulin promotes pH and viscosity independence at low speed and promotes pH and viscosity dependence at high speed in the lubrication of UHMWPE against SUS. This study supports the clinical hypothesis that the effect of constituents and pH changes in periprosthetic fluid for the lubrication is a clue toward resolving many complications after total joint replacement.

Reconstruction of the basement membrane in a cultured submandibular gland.

In a rat submandibular rudiment on day 16, both laminin (LM) and type IV collagen (Col-IV) were found in all cases to colocalize not only in the basement membrane, but also in the rough endoplasmic reticulum of the epithelial cells, indicating that the synthesis of the components of basement membrane is greatly enhanced at this particular stage of extensive branch formation. Using the submandibular gland from a 16-day embryo, the model system was developed to determine the structural organization of the basement membrane. The pre-existing basement membrane was digested with collagenase and dispase, causing its complete disappearance. The subsequent gradual reconstruction of an authentic basement membrane was confirmed by electron microscopy and immunohistochemistry of LM and Col-IV. In the model system, this recovery started at 4 h of culture, and formation was complete by 8 h. During the recovery, thick bundles of actin filaments appeared transitionally in the basal cytoplasm. Electron microscopic analysis indicated two precursor structures, aggregated fuzzy fibers (type 1 extracellular matrix (ECM)) and 10-nm-thick strand piles (type 2 ECM), and an authentic basement membrane structure appeared during the course of membrane reconstruction. LM and Col-IV were always located together in these three structures. These observations clearly indicate that the precursors, containing LM, Col-IV and most likely heparan sulfate proteoglycan, appeared to form immediately following their secretion into the extracellular space, and assembled into the rigid structure of basement membrane within 8 h. The ultrastructural and immunohistochemical process of basement membrane reconstruction appeared to coincide closely with that of the glomerular basement membrane in developing kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

The flexion gap in normal knees. An MRI study.

Varus and valgus joint laxity of the normal living knee in flexion was assessed using MRI. Twenty knees were flexed to 90 degrees and were imaged in neutral and under a varus-valgus stress in an open MRI system. The configuration of the tibiofemoral joint gap was studied in slices which crossed the epicondyles of the femur. When a varus stress was applied, the lateral joint gap opened by 6.7 +/- 1.9 mm (mean +/- SD; 2.1 to 9.2) whereas the medial joint gap opened by only by a mean of 2.1 +/- 1.1 mm (0.2 to 4.2). These discrepancies indicate that the tibiofemoral flexion gap in the normal knee is not rectangular and that the lateral joint gap is significantly lax. These results may be useful for adequate soft-tissue balancing and bone resection in total knee arthroplasty and reconstruction surgery on ligaments.

Tibiofemoral movement 3: full flexion in the living knee studied by MRI.

We studied active flexion from 90 degrees to 133 degrees and passive flexion to 162 degrees using MRI in 20 unloaded knees in Japanese subjects. Flexion over this arc is accompanied by backward movement of the medial femoral condyle of 4.0 mm and by backward movement laterally of 15 mm, i.e., by internal rotation of the tibia. At 162 degrees the lateral femoral condyle lies posterior to the tibia.

Number of polyethylene particles and osteolysis in total joint replacements. A quantitative study using a tissue-digestion method.

Our aim was to analyse the influence of the size, shape and number of particles on the pathogenesis of osteolysis. We obtained peri-implant tissues from 18 patients having revision surgery for aseptically loosened Freeman total knee replacements (10), Charnley total hip replacements (3) and Imperial College/London Hospital double-cup surface hip replacements (5). The size and shape of the polyethylene particles were characterised using SEM and their concentration was calculated. The results were analysed with reference to the presence of radiological osteolysis. The concentration of polyethylene particles in 6 areas with osteolysis was significantly higher than that in 12 areas without osteolysis. There were no significant differences between the size and shape of the particles in these two groups. We conclude that the most critical factor in the pathogenesis of osteolysis is the concentration of polyethylene particles accumulated in the tissue.

Wear and osteolysis in total joint replacements.

UNLABELLED: This presentation summarizes the results of our recent studies on the pathogenesis of osteolysis around total joint arthroplasties. First, interface tissues with adjacent bone were retrieved and histopathologically investigated with reference to the cells on the bone surface. Secondly, polyethylene particles were extracted with the tissue digestion method and characterized with scanning electron microscopy. Finally, an animal model for osteolysis was created and various interface conditions were compared concerning their resistance to particle migration. Histopathological examinations demonstrated that active bone formation, regarded as a repair process, was the commonest feature, even in revised cases. They also highlighted the role played by macrophages, not as cells producing inflammatory mediators which could activate osteoclasts, but as cells primarily responsible for the bone loss in osteolytic lesions. Among the particle species present, only polyethylene particles were shown to play a significant role in macrophage recruitment and subsequent osteolysis. A quantitative extraction of polyethylene particles showed a significant difference in the "number" of particles between osteolysis positive and negative cases whereas the "sizes" of particles were similar in these two groups. The critical number of particles for osteolysis was around 1 x 10(10) particles/g tissue and the cellular reaction against phagocytosable particles accumulated over this concentration may be the prerequisite for progression of osteolysis. The animal model for osteolysis indicated that the progression of osteolysis depends on the integrity of the bone-implant interface. We suggest that the solid fixation of the prosthesis performed by current techniques (e.g., improved cementing technique, hydroxyapatite coating) is beneficial for preventing particle migration and subsequent osteolysis. CLINICAL RELEVANCE: Osteolysis induced by particulate wear debris from implant materials has been recognized as the major cause of long-term failure in total joint replacements. However, the development of preventive measures for this phenomenon has not been successful because the mechanism in which wear particles cause osteolysis is not quite clear. On the basis of results obtained in this study, we believe that the basic strategy for addressing the problem of osteolysis is to reduce the "number" of accumulated wear particles in the interface tissues. This could be achieved either by improving the materials or the geometry of the articulating counterface. Another possibility is to increase the integrity of the bone-implant interface to prevent particle migration. It is important to note that pre-clinical testing of materials and prosthetic designs should include an analysis of the characteristics of the particle generated (e.g., size and number). The widespread bone formation, even in revised cases, is encouraging in view of "conservative treatment" of aseptic loosening. Assuming that bone loss in aseptic loosening is not a remorseless process, some form of intervention, whether mechanical or pharmacological, might be possible to tip the balance more in favour of bone formation than resorption. A comprehensive understanding of the bone reactions in osteolysis, including the basic mechanisms of bone loss, shown in this study, are decisive for the development of preventive measures that may minimize the clinical impact of this phenomenon.