Antibacterial coating of orthodontic elastomeric ligatures with silver and bismuth nanofilms by magnetron sputtering: A feasibility study.

OBJECTIVES: Magnetron sputtering was evaluated to equip surfaces of orthodontic elastomeric ligatures with silver and bismuth nanofilms. MATERIAL AND METHODS: Antibacterial properties were evaluated by the adhesion of Streptococcus mutans. Polyurethane-based elastomeric ligatures were coated with silver and bismuth nanofilms via direct current magnetron sputtering. Surface roughness (Ra ) and surface-free energy (SFE) were assessed. Coated specimens were incubated with S. mutans for 2 h. Adhering bacteria were visualized by Hoechst staining and quantified by an ATP-based luminescence assay. One-way analysis of variance with Tukey post hoc testing and Pearson correlation analysis were performed (p < .05) to relate bacterial adhesion to surface roughness and surface-free energy. RESULTS: Elastomeric ligatures were successfully coated with silver and bismuth nanofilms. Ra was significantly reduced by silver coating. Silver and bismuth coatings showed significantly higher SFE than controls. Adhesion of S. mutans was significantly decreased by silver coating. No correlation between bacterial adhesion and SFE was found. Correlation between bacterial adhesion and Ra was positive but not statistically significant. CONCLUSIONS: Magnetron sputtering proved to be a feasible method to equip orthodontic elastomeric ligatures with silver and bismuth nanofilms. Silver coatings of elastomeric ligatures may reduce white spots and carious lesions in orthodontic patients. Future research is required to stabilize coatings.

Changes in Maximum Mandibular Mobility Due to Splint Therapy in Patients with Temporomandibular Disorders.

Splint therapy is widely used in the treatment of myofascial pain, but valid studies on the efficacy of this therapy are rare. The purpose of the present study was to investigate which qualifiable and quantifiable effects of splint therapy are detectable. For this purpose, 29 patients (21 women, mean age 44.6 ± 16 years) diagnosed with myofascial pain (RDC/TMD) were investigated in this prospective clinical trial (10/6/14An). Patients were treated with Michigan splints applied overnight for three months. Before (T1) and after three months of treatment (T2), patients were registered with an electronic ultrasound device with qualitative and quantitative evaluation of the registrations and a qualitative assessment of pain symptoms using a verbal analog scale. Significant differences were found between maximum mouth opening (MMP) (p < 0.001) and right condylar movement (CM) at MMP (p = 0.045). Qualitative assessment revealed that 24 of 29 patients experienced an improvement in pain symptoms, 17 of whom experienced complete remission. The results of the qualitative and quantitative analysis provide indications of the effectiveness of the splint therapy. In addition to quantitative measurements, the ultrasound facebow technique was also able to provide qualitative information.

Removal forces of adhesively and self-adhesively luted implant-supported zirconia copings depend on abutment geometry.

This in vitro study evaluated the effects of different abutment axial heights on the retentiveness of adhesively and self-adhesively luted zirconia copings. Ankylos implants were embedded in resin blocks. Two groups of titanium abutments ("long", height: 6.79 mm, taper: 4.8°; "short", height: 4.31 mm, taper: 4.8°; Compartis-ISUS, DeguDent) were used for the luting of CAD/CAM-fabricated zirconia copings (Compartis, DeguDent) with an adhesive (Multilink Automix; Ivoclar Vivadent) and a self-adhesive (RelyX Unicem; 3M ESPE) composite. After water storage and 5000 thermocycles (5 °C/55 °C), retention forces were evaluated using a universal testing machine (Zwick). Significant differences were determined via two-way ANOVA and t-tests with Bonferroni-Holm correction. Significant interactions between abutment geometry and luting agents were observed. RelyX Unicem showed the highest levels of retentiveness, irrespective of the varying abutment geometries (mean values long/short: 487.7 N/447.9 N). When Multilink Automix was used, removal forces were significantly lower (311.7 N/101.1 N) and negatively affected by the use of the shorter abutments. Customized long abutments supported better retention forces than customized short abutments for both luting agents.

Real-time MRI of the temporomandibular joint at 15 frames per second-A feasibility study.

The purpose of this study was to develop and evaluate a novel method for real-time MRI of TMJ function at high temporal resolution and with two different contrasts. Real-time MRI was based on undersampled radial fast low angle shot (FLASH) acquisitions with iterative image reconstruction by regularized nonlinear inversion. Real-time MRI movies with T1 contrast were obtained with use of a radiofrequency-spoiled FLASH sequence, while movies with T2/T1 contrast employed a gradient-refocused FLASH version. TMJ function was characterized in 40 randomly selected volunteers by sequential 20s acquisitions of both the right and left joint during voluntary opening and closing of the mouth (in a medial, central and lateral oblique sagittal section perpendicular to the long axis of the condylar head). All studies were performed on a commercial MRI system at 3T using the standard head coil, while online reconstruction was achieved with a bypass computer fully integrated into the MRI system. As a first result, real-time MRI studies of the right and left TMJ were successfully performed in all 40 subjects (80 joints) within a total examination time per subject of only 15min. Secondly, at an in-plane resolution of 0.75mm and 5mm section thickness, the achieved temporal resolution was 66.7ms per image or 15 frames per second. Thirdly, both T1-weighted and T2/T1-weighted real-time MRI movies provided information about TMJ function such as disc position, condyle mobility and disc-condyle relationship. While T1 contrast offers a better delineation of structures during rapid jaw movements, T2/T1 contrast was rated superior for characterizing the articular disc. In conclusion, the proposed real-time MRI method may become a robust and efficient tool for the clinical assessment of TMJ function.

Implant-supported overdentures with different bar designs: A retrospective evaluation after 5-19 years of clinical function.

PURPOSE: This retrospective study evaluated the outcome of implant-retained overdentures (IODs) after 5-19 years of clinical function. MATERIALS AND METHODS: A retrospective analysis of patient files was performed referring to 27 patients who received 36 IODs with 3 different bar designs (group A=prefabricated round bars, n=7; group B=one-piece anterior milled bars, n=20; and group C=two bilaterally placed milled bars, n=9) in the mandible (n=24) and/or in the maxilla (n=12). The analysis focused on the survival and success rates (according to Kaplan-Meier) of the implants and prostheses. Technical complication rates for each type of restoration were analyzed and compared via one-way ANOVA and the Chi-squared test. The prevalence of peri-implantitis (radiographic bone loss ≥3.5 mm) was evaluated by digital analysis of panoramic radiographs taken post-operative (baseline) and after 5-19 years of clinical function (follow-up). RESULTS: The mean observational time was 7.3 years. The survival rates of the prostheses and implants were 100% and 97.7%, respectively. Technical complications occurred more frequently in group A (mean: 3.5 during observational time) than in the other two groups (B: 0.8; C: 1.0). However, this difference was not statistically significant (P=0.58). Peri-implantitis was diagnosed for 12.4% of the implants in 37% of the patients. CONCLUSION: Bar-retained IODs are an adequate treatment option for edentulous jaws. These restorations may exhibit high implant/prosthesis survival rates (>97%), and a limited incidence of technical complications after a mean observational period of >7 years. Nevertheless, peri-implantitis was identified as a frequent and serious biological complication for this type of reconstruction.

Risk factors for technical and biological complications with zirconia single crowns.

OBJECTIVES: This practice-based study evaluated the clinical performance and risk factors for biological and technical complications with conventionally luted zirconia crowns. MATERIALS AND METHODS: Sixty-eight patients (39 female) with a total of 323 restorations placed on 219 vital teeth, 69 endodontically treated teeth (ETT), and 41 implants (incisors, 96; premolars, 89; molars, 138; observational period, 79.7 ± 14.2 months) underwent a clinical follow-up examination and were included in the study. Time-dependent survival (in situ), success (event free), and veneering ceramic fracture (VCF) rates were calculated and analyzed relative to the following risk factors: smoking status, location of the crown, and type of abutment. RESULTS: Fifty-three complete failures were recorded. A significant influence of the abutment type on survival could be detected (p = 0.033): ETT demonstrated a significantly (p = 0.029) lower 7-year survival rate (73.8%, 95% confidence interval [95% CI] 0.600-0.876) than crowns placed on implants (90.0%, 95% CI 0.814-0.990). The success rate of the crowns was significantly influenced by the location of the restoration (p = 0.0058). A total of 75.6% (95% CI 0.648-0.864) of the anterior crowns remained event free, compared to 50.4% (95% CI 0.388-0.621) of the molar crowns. Furthermore, the location of the crowns affected the VCF rate (p = 0.018, event-free anterior teeth 95.2% (95% CI 0.880-1), event-free molars 80.9% (95% CI 0.706-0.913)). CONCLUSIONS: Survival and success rates were significantly influenced by the type of abutment and the location of the restoration. CLINICAL RELEVANCE: More complete failures should be expected for crowns placed on ETT, while crowns on molars demonstrated more biological and technical complications than anterior zirconia crowns.

Evaluation of removal forces of implant-supported zirconia copings depending on abutment geometry, luting agent and cleaning method during re-cementation.

PURPOSE: To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS: Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: 5.7°; customized-long, height: 6.79 mm, taper: 4.8°; customized-short, height: 4.31 mm, taper: 4.8°) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: 5.7°) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS: Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION: No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting.

Anisotropic local physical properties of human dental enamel in comparison to properties of some common dental filling materials.

OBJECTIVE: A major aspect in evaluating the quality of dental materials is their physical properties. Their properties should be a best fit of the ones of dental hard tissues. Manufacturers give data sheets for each material. The properties listed are characterized by a specific value. This assumes (but does not prove) that there is no direction dependence of the properties. However, dental enamel has direction-dependent properties which additionally vary with location in the tooth. The aim of this paper is to show the local direction dependence of physical properties like the elastic modulus or the thermal expansion in dental hard tissues. With this knowledge the 'perfect filling/dental material' could be characterized. MATERIALS AND METHOD: Enamel sections of ∼400-500 µm thickness have been cut with a diamond saw from labial/buccal to palatal/lingual (canine, premolar and molar) and parallel to labial (incisor). Crystallite arrangements have been measured in over 400 data points on all types of teeth with x-ray scattering techniques, known from materials science. RESULTS: X-ray scattering measurements show impressively that dental enamel has a strong direction dependence of its physical properties which also varies with location within the tooth. Dental materials possess only little or no property direction dependence. Therefore, a mismatch was found between enamel and dental materials properties. CONCLUSION: Since dental materials should possess equal (direction depending) properties, worthwhile properties could be characterized by transferring the directional properties of enamel into a property 'wish list' which future dental materials should fulfil. Hereby the 'perfect dental material' can be characterized.

A discoidin domain receptor 1 knock-out mouse as a novel model for osteoarthritis of the temporomandibular joint.

Discoidin domain receptor 1 (DDR-1)-deficient mice exhibited a high incidence of osteoarthritis (OA) in the temporomandibular joint (TMJ) as early as 9 weeks of age. They showed typical histological signs of OA, including surface fissures, loss of proteoglycans, chondrocyte cluster formation, collagen type I upregulation, and atypical collagen fibril arrangements. Chondrocytes isolated from the TMJs of DDR-1-deficient mice maintained their osteoarthritic characteristics when placed in culture. They expressed high levels of runx-2 and collagen type I, as well as low levels of sox-9 and aggrecan. The expression of DDR-2, a key factor in OA, was increased. DDR-1-deficient chondrocytes from the TMJ were positively influenced towards chondrogenesis by a three-dimensional matrix combined with a runx-2 knockdown or stimulation with extracellular matrix components, such as nidogen-2. Therefore, the DDR-1 knock-out mouse can serve as a novel model for temporomandibular disorders, such as OA of the TMJ, and will help to develop new treatment options, particularly those involving tissue regeneration.

Prospective evaluation of zirconia posterior fixed partial dentures: 7-year clinical results.

PURPOSE: The clinical performance of three- and four-unit fixed partial dentures (FPDs) with frameworks made of yttria partially stabilized zirconia was determined after a mean observational period of 84 months. MATERIALS AND METHODS: Seventy-five patients were treated with 99 posterior FPDs. Fifty-one specimens were veneered with an experimental ceramic suitable for titanium and zirconia frameworks; 48 restorations were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks. All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to Kaplan-Meier; potential risk factors were analyzed using the Cox regression analysis. RESULTS: Nineteen restorations failed completely: 12 due to technical complications, 6 due to biologic complications, and 1 for unknown reasons. The overall survival rate after 84 months was 83.4%. Thirty-two events required clinical intervention for restoration maintenance, resulting in a time-dependent success rate of 57.9% after 84 months. Nineteen dropouts occurred during the follow-up time. None of the evaluated factors showed an association with survival or success of the restorations. CONCLUSIONS: After a mean observational period of 7 years, the survival and success rates of zirconia-based posterior FPDs were inferior to those published for metal-ceramic FPDs. The majority of failures were caused by technical complications (material fractures). The main reasons for clinical intervention to maintain function were fractures of the veneering ceramic and decementations.

Multifactorial analysis of the impact of different manufacturing processes on the marginal fit of zirconia copings.

This study evaluated the effect of different parameters on the marginal precision of CAD/CAM-fabricated zirconia copings. Specimens(n=60) were fabricated with two different scanners and two milling systems. The copings were evaluated with respect to their mean and average maximum marginal gaps. A two-way analysis of variance (ANOVA) (α=0.05) was used to evaluate the effect of different parameters (scanner, milling process) on marginal accuracy. The mean (averaged maximum) marginal gaps ranged from 57.9 (112.2 µm) to 71.0 (144.6 µm) in the "as machined" state. After manual adaptation, the respective values ranged from 54.6 (98.0 µm) to 59.9(107.7 µm). The system and manual adaptation variables were found both to have multiple significant effects on the marginal gap size and to have a complex interaction. Thus, synchronized/validated processing chains should be preferentially used to guarantee optimal fitting accuracy for CAD/CAM zirconia restorations.

Tissue distribution of the laminin beta1 and beta2 chain during embryonic and fetal human development.

Laminins are the major glycoproteins present in all basement membranes. Previously, we showed that perlecan is present during human development. Although an overview of mRNA-expression of the laminin beta1 and beta2 chains in various developing fetal organs is already available, a systematic localization of the laminin beta1 and beta2 chains on the protein level during embryonic and fetal human development is missing. Therefore, we studied the immunohistochemical expression and tissue distribution of the laminin beta1 and beta2 chains in various developing embryonic and fetal human organs between gestational weeks 8 and 12. The laminin beta1 chain was ubiquitously expressed in the basement membrane zones of the brain, ganglia, blood vessels, liver, kidney, skin, pancreas, intestine, heart and skeletal system. Furthermore, the laminin beta2 chain was present in the basement membrane zones of the brain, ganglia, skin, heart and skeletal system. The findings of this study support and expand upon the theory that these two laminin chains are important during human development.

Prospective evaluation of zirconia posterior fixed partial dentures: four-year clinical results.

PURPOSE: In this prospective clinical study, the performance of three- and four-unit fixed partial dentures (FPDs) with frameworks fabricated of yttria partially stabilized zirconia was determined after a mean observation period of 50 months. The study focused on the survival of the restoration (in situ criterion) and the success of the ceramic veneers (no defect). MATERIALS AND METHODS: Seventy-five patients with a maximum of two missing teeth and an antagonistic dentition were treated at the Department of Prosthodontics, University of Goettigen, with 99 posterior FPDs. Fifty-one specimens (experimental group) were veneered with an experimental ceramic suitable for titanium and zirconia frameworks (thermal expansion coefficient [TEC]: 8.5 microm/m*K); 48 restorations (Ceram-S group) were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks (TEC: 9.5 microm/m*K). All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to the Kaplan-Meier method; time-dependent success rates of the different types of ceramic veneers were analyzed using the log-rank test. RESULTS: Seven restorations were lost: 4 due to technical complications and 3 due to biologic complications. The overall survival rate after 48 months was 94% (Kaplan-Meier analysis). Twenty-three events required clinical intervention for restoration maintenance: 13 ceramic veneer chippings (polishing), 6 losses of retention (recementation), 3 caries lesions (filling therapy), and 1 loss of vitality (endodontic treatment). Between the two groups of veneering materials, no significant difference in the probability for success was determined (log-rank test, P=.81). CONCLUSIONS: Within a mean observation period of 4 years, sufficient survival rates for zirconia-based posterior FPDs could be verified. The main complications included fracture of the ceramic veneering material and decementation, which occurred mainly in the mandible.

Organic anion transporter 3 (OAT3) and renal transport of the metal chelator 2,3-dimercapto-1-propanesulfonic acid (DMPS).

Recent investigations involving intact rabbit renal proximal tubules indicated that organic anion transporter 3 (OAT3) may be involved in the transport of 2,3-dimercapto-1-propanesulfonic acid (DMPS). Therefore, we evaluated the interaction of OAT3 with DMPS to determine the effect of OAT3 on basolateral DMPS uptake. We used stably transfected HEK293 cells expressing human and rabbit orthologs of the exchanger OAT1 and OAT3. Using 6-carboxyfluorescein (6-CF) as a substrate, the IC50 determinations for reduced DMPS (DMPSH) revealed a stronger interaction with OAT1 than with OAT3 (rbOAT1, 123.3 +/- 13.7; hOAT1, 85.1 +/- 8.8; rbOAT3, 171.7 +/- 22.3; and hOAT3, 172.2 +/- 36.4 micromol/L). However, inhibition of 6-CF uptake by the oxidized form of DMPS (DMPSS), the main form of DMPS in the blood, showed a greater affinity for OAT3 (rbOAT1, 237.4 +/- 23; hOAT1, 104.6 +/- 13.1; rbOAT3, 52.4 +/- 7.6; and hOAT3, 31.6 +/- 6.6 micromol/L). To determine whether DMPSH and DMPSS are substrates for OAT3, we performed efflux studies with [14C]glutarate and inwardly directed gradients of glutarate. The inhibitors trans-stimulated the efflux of [14C]glutarate, suggesting that OAT3 may be able to transport both forms of DMPS. On the basis of the substantial interaction of OAT3 with DMPSS, we conclude that OAT3 represents the dominant basolateral player in renal detoxification processes resulting from use of DMPS.

Tissue distribution of perlecan domains III and V during embryonic and fetal human development.

A major component of basement membranes (BMs) is perlecan, a five-domain heparan sulphate proteoglycan. During murine embryogenesis, nearly all BMs of mesenchymal origin express perlecan, and it is believed to participate in the supramolecular assembly of BMs. However, the distribution of perlecan in human embryonic and fetal tissues is widely unknown, except for cartilage anlagen of developing extremities and the fetal spine. Clinical syndromes, caused by perlecan-associated mutations or gene-defects, suggest its multifunctional involvement during human development. Here we reveal the immunohistochemistry of perlecan domains III and V during human development from gestational weeks (gw) 6 to 12 in basement membrane zones (BMZs) of the developing brain, nervous system, blood vessels, skin, lung, heart, kidney, liver, intestine and skeletal system. Interestingly, a difference in the distribution of the two perlecan domains was found in the endoneurium of ganglia. Domain III is strongly present from gw 6 onwards, while domain V shows attenuated expression at this stage and has been detected abundantly only from gw 8 onwards, possibly indicating vascularization of the endoneurium during this early stage. We found perlecan to be present particularly at those stages of human development where epithelial-mesenchymal interactions occur.

Secreted modular calcium-binding protein-1 localization during mouse embryogenesis.

BM-40 is an extracellular matrix-associated protein and is characterized by an extracellular calcium-binding domain as well as a follistatin-like domain. Secreted modular calcium-binding protein-1 (SMOC-1) is a new member of the BM-40 family. It consists of two thyroglobulin-like domains, a follistatin-like domain and a new domain without known homologues and is expressed ubiquitously in many adult murine tissues. Immunofluorescence studies, as well as immunogold electron microscopy, have confirmed the localization of SMOC-1 in or around basement membranes of adult murine skin, blood vessels, brain, kidney, skeletal muscle, and the zona pellucida surrounding the oocyte. In the present work, light microscopic immunohistochemistry has revealed that SMOC-1 is localized in the early mouse embryo day 7 throughout the entire endodermal basement membrane zone of the embryo proper. SMOC-1 mRNA is synthesized, even in early stages of mouse development, by mesenchymal as well as epithelial cells deriving from all three germ layers. In embryonic stage day 12, and fetal stages day 14, 16, and 18, the protein is present in the basement membrane zones of brain, blood vessels, skin, skeletal muscle, lung, heart, liver, pancreas, intestine, and kidney. This broad and organ-specific distribution suggests multifunctional roles of SMOC-1 during mouse embryogenesis.

Localization of Apaf1 gene expression in the early development of the mouse by means of in situ reverse transcriptase-polymerase chain reaction.

Apoptosis is an essential ubiquitous process that controls the duration of the life span of cells, thus playing a crucial role in morphogenetic, histogenetic, and phylogenetic developmental processes. Apaf1 (apoptosis protease activating factor 1) is one of the central mediators of the intrinsic apoptotic pathway and a part of the apoptosome, which activates procaspase-3 and promotes cell death. Gene knockout of Apaf1 in mice leads to late embryonic lethality with malformations such as the persistence of interdigital webs and hyperplasia of brain and retina. Therefore, Apaf1 is generally believed to play a crucial role in developmental apoptosis and have a widespread expression. However, its pattern of expression in early development remains unknown. To specify whether Apaf1 indeed plays this key role, we investigated the pattern of gene expression for Apaf1 in mouse embryos on day 7, 9, and 12 of development. Our results show, that gene expression for Apaf1 first occurs within the embryo between day 7 and 9 of development, becoming more widespread toward day 12 and then includes structures, such as yolk sac, mesenchyme, cartilage, heart anlage, otic vesicle, peridermis, and anlagen of the spinal ganglia and vertebral bodies. Our results also show that gene expression for Apaf1 is not ubiquitous in early mouse development. This finding indicates that cell death processes are independent of or less dependent on Apaf1 during this time. Of interest, an active gene expression for Apaf1 is also present in organ anlagen such as heart or intestine, in which no obvious phenotype is seen after Apaf1 deletion. This finding suggests a possible role for Apaf1 in such anlagen as a putative alternative compensatory pathway, which could be switched on in the case of defects in the mediators that are normally involved in such organs.

Basement membrane composition in the early mouse embryo day 7.

Basement membranes (BM) are specialized structures of the extracellular matrix known to be involved in various early developmental processes. Despite numerous investigations on the localization of BM components, it remains unknown which molecules are expressed in early developmental stages and by which germ layers these proteins are produced. Therefore, we tested for all known laminin chains, nidogens, collagen type IV, and perlecan by means of light microscopic immunostaining and performed in situ reverse transcriptase-polymerase chain reaction to detect the mRNAs specific for laminin alpha1, laminin beta1, the alpha1 chain of collagen type IV, nidogen-2, and perlecan in the early mouse embryo, day 7, in vivo. Only the laminin chains alpha1, beta1, and gamma1 were detected immunohistochemically throughout the entire endodermal and ectodermal BM zones of the embryo proper. The mRNA of laminin alpha1, laminin beta1, collagen type IV, nidogen-2 and perlecan were expressed in the ectoderm-derived mesoderm, in the endoderm as well as in the ectoderm. In contrast, Reichert's membrane was positive for all laminin chains except for the alpha4, alpha5, beta3, and gamma3 chains. Moreover, maternal epithelial as well as mesenchymal cells expressed laminins, nidogen-1 and nidogen-2, collagen type IV, and perlecan. In conclusion, laminin-1 might be the only laminin isoform in the early mouse embryo that, together with the other main BM components, nidogens, collagen type IV, and perlecan, is synthesized by all three germ layers.

Laminin gamma3 chain binds to nidogen and is located in murine basement membranes.

Recently a novel laminin gamma3 chain was identified in mouse and human and shown to have the same modular structure as the laminin gamma1 chain. We expressed two fragments of the gamma3 chain in mammalian cells recombinantly. The first, domain VI/V, consisting of laminin N-terminal (domain VI) and four laminin-type epidermal growth factor-like (domain V) and laminin N-terminal modules, was shown to be essential for self-assembly of laminins. The other was domain III3-5, which consists of three laminin-type epidermal growth factor-like modules and is predicted to bind to nidogens. The gamma3 VI/V fragment was a poor inhibitor for laminin-1 polymerization as was the beta2 VI/V fragment. The gamma3 III3-5 fragment bound to nidogen-1 and nidogen-2 with lower affinity than the gamma1 III3-5 fragment. These data suggested that laminins containing the gamma3 chain may assemble networks independent of other laminins. Polyclonal antibodies raised against gamma3 VI/V and gamma3 III3-5 showed no cross-reaction with homologous fragments from the gamma1 and gamma2 chains of laminin and allowed the establishment of gamma chain-specific radioimmunoassays and light and electron microscopic immunostaining of tissues. This demonstrated a 20-100-fold lower content of the gamma3 chain compared with the gamma1 chain in various tissue extracts of adult mice. The expression of gamma3 chain was highly tissue-specific. In contrast to earlier assumptions, the antibodies against the gamma3 chain showed light microscopic staining exclusively in basement membrane zones of adult and embryonic tissues, such as the brain, kidney, skin, muscle, and testis. Ultrastructural immunogold staining localized the gamma3 chain to basement membranes of these tissues.