Curcumin and Teupolioside attenuate signs and symptoms severity associated to hirsutism in PCOS women: a preliminary pilot study

OBJECTIVE

Hirsutism affects 5-15% of women of reproductive age, with approximately 80% of these women having polycystic ovary syndrome (PCOS). The etiopathogenesis of PCOS remains unclear, the clinical characteristics of PCOS include hyperandrogenism, generally manifested as hirsutism and acne, and both these clinical symptoms are treated with oral contraceptive pills (OCPs), topical medications or antiandrogens. Curcumin (diferuloylmethane) and Plant sterols, such as a phenylpropanoid glycosides of Ajuga reptans, known as Teupolioside, have attracted considerable attention due to their pharmacological properties. Taking into consideration wide-ranging pharmacological and biological properties and the safety of herbal extracts, we proposed a combination of curcumin and teupolioside to evaluate the anti-androgenic properties in women with PCOS and clinical signs of hyperandrogenism.

PATIENTS AND METHODS

Six hyperandrogenic PCOS women with a hirsutism score (HS) > 20, according to Ferriman-Gallwey scoring system, were involved in the study. These women were treated with a galenical preparation mixture containing curcumin and teupolioside and clinical features were assessed after 12 weeks.

RESULTS

The nutraceutical combination containing curcumin/teopolioside ameliorated clinical manifestations associated to hyperandrogenism in women with PCOS after a 12-weeks treatment.

CONCLUSIONS

This pilot study suggests that a curcumin/teopolioside nutraceutical combination is beneficial for improving various clinical manifestations associated to abnormal hormonal parameters in PCOS women, as well as signs and symptoms associated to hyperandrogenism.

Wnt/β-Catenin Signaling Promotes the Formation of Preodontoblasts In Vitro

Odontoblast differentiation is a complex and multistep process regulated by signaling pathways, including the Wnt/β-catenin signaling pathway. Both positive and negative effects of Wnt/β-catenin signaling on dentinogenesis have been reported, but the underlying mechanisms of these conflicting results are still unclear. To gain a better insight into the role of Wnt/β-catenin in dentinogenesis, we used dental pulp cells from a panel of transgenic mice, in which fluorescent protein expression identifies cells at different stages of odontoblast and osteoblast differentiation. Our results showed that exposure of pulp cells to WNT3a at various times and durations did not induce premature differentiation of odontoblasts. These treatments supported the survival of undifferentiated cells in dental pulp and promoted the formation of 2.3GFP⁺ preodontoblasts and their rapid transition into differentiated odontoblasts expressing DMP1-Cherry and DSPP-Cerulean transgenes. WNT3a also promoted osteogenesis in dental pulp cultures. These findings provide critical information for the development of improved treatments for vital pulp therapy and dentin regeneration.

Women Recipients of IADR Distinguished Scientist Awards

The International Association for Dental Research (IADR) Distinguished Scientist Awards are prestigious recognitions of outstanding scientific accomplishments in various areas of dental, oral, and craniofacial research, which correspond to several of the IADR Scientific Groups and Networks. These 17 awards were established over a period of 60 y. The objective of this report is to highlight women recipients of IADR Distinguished Scientist Awards. Additionally, we report the distribution of awards to women scientists over time and compare the number of women nominees, awardees, and gender distribution of the membership. Information about the awards was obtained from the IADR member database and press releases. Information collected included name of the award, year received, and the awardee's name, institution, and position held at the time of the award. For the last 14 y, the time span for which reliable information was available, the gender distribution of the membership of the IADR was also retrieved. Overall, only 13% of the awardees have been women; even in the last 20 y, <20% have been women. In the last 14 y, the number of women awardees paralleled the number of nominees for each award. However, the proportion of women nominees was significantly lower than the female membership each year (P < 0.001). With the exception of 1 y, the percentage of women awardees trailed the women membership of the IADR. In the past 4 y, women represented 12% to 18% of the awardees, whereas they composed 41% to 46% of the IADR's membership. Given the benefits of prestigious recognitions on recruitment and retention of faculty and on attracting new research trainees into a discipline, it is important that policies be implemented to increase the proportion of women nominees for awards to appropriately recognize the efforts of remarkable women scientists.

Comparison of osteogenic and dentinogenic potentials of mice incisor and molar pulps in vitro

OBJECTIVE

In the present study, we compared the in vitro osteogenic and dentinogenic potential of pulp cells from incisors and molars.

DESIGN

Primary pulp cultures were established from DSPP-Cerulean/DMP1-Cherry and BSP-GFPtpz reporter mouse lines and processed for various assays.

RESULTS

Our results showed marked differences in dentinogenic and osteogenic potentials of primary cultures from unerupted molars and incisors isolated from 5 to 7 days old pups. While primary cultures from both incisors and molars differentiated into odontoblasts and osteoblasts, cultures from molars differentiated into more DSPP-Cerulean + cells (∼5.5 %) compared to incisor cultures (∼0.7 %) at Day 14 and appear to be more committed to the odontogenic lineage. On the other hand, cultures from incisors show more differentiation into BSP-GFPtpz + cells (∼25 %) compared to molar cultures (∼16 %) and were more committed to the osteogenic lineage. Data were analyzed by Student's t-test and statistical significance was set at P ≤ 0.05.

CONCLUSION

Since in the dental pulp, MSCs are the primary source of progenitors capable of giving rise to osteoblasts and odontoblasts, our results provide evidence for differences in the commitment of MSCs in molars and incisors to the odontogenic and osteogenic lineages, respectively.

Expression of BSP-GFPtpz Transgene during Osteogenesis and Reparative Dentinogenesis

Bone sialoprotein (BSP) is a member of the SIBLING family with essential roles in skeletogenesis. In the developing teeth, although the expression and function of BSP in the formation of acellular cementum and periodontal attachment are well documented, there are uncertainties regarding the expression and function of BSP by odontoblasts and dentin. Reporter mice are valuable animal models for biological research, providing a gene expression readout that can contribute to cellular characterization within the context of a developmental process. In the present study, we examined the expression of a BSP-GFPtpz reporter mouse line during odontoblast differentiation, reparative dentinogenesis, and bone. In the developing teeth, BSP-GFPtpz was expressed at high levels in cementoblasts but not in odontoblasts or dentin. In bones, the transgene was highly expressed in osteoblasts at an early stage of differentiation. Interestingly, despite its lack of expression in odontoblasts and dental pulp during tooth development, the BSP-GFPtpz transgene was detected during in vitro mineralization of primary pulp cultures and during reparative dentinogenesis following pulp exposures. Importantly, under these experimental contexts, the expression of BSP-GFPtpz was still exclusive to DSPP-Cerulean, an odontoblast-specific reporter gene. This suggests that the combinatorial use of BSP-GFPtpz and DSPP-Cerulean can be a valuable experimental tool to distinguish osteogenic from dentinogenic cells, thereby providing an avenue to investigate mechanisms that distinctly regulate the lineage progression of progenitors into odontoblasts versus osteoblasts.

Activation of αSMA expressing perivascular cells during reactionary dentinogenesis

AIM

To examine the contribution of perivascular cells expressing αSMA to reactionary dentinogenesis.

METHODOLOGY

An inducible, Cre-loxP in vivo fate-mapping approach was used to examine the contribution of the descendants of cells expressing the αSMA-CreERT2 transgene to reactionary dentinogenesis in mice molars. Reactionary dentinogenesis was induced by experimental mild injury to dentine without pulp exposure. The Student's t test was used to determine statistical significance at *P ≤ 0.05.

RESULTS

The lineage tracing experiments revealed that mild injury to dentine first led to activation of αSMA-tdTomato+ cells in the entire pulp chamber. The percentage of areas occupied by αSMA-tdTomato+ in injured (7.5 ± 0.7%) teeth were significantly higher than in teeth without injury (2 ± 0.5%). After their activation, αSMA-tdTomato+ cells migrated towards the site of injury, gave rise to pulp cells and a few odontoblasts that became integrated into the existing odontoblast layer expressing Col2.3-GFP and Dspp.

CONCLUSION

Mild insult to dentine activated perivascular αSMA-tdTomato+ cells giving rise to pulp cells as well as a few odontoblasts that were integrated into the pre-existing odontoblast layer.

FGF2 Enhances Odontoblast Differentiation by αSMA+ Progenitors In Vivo

The goal of this study was to examine the effects of early and limited exposure of perivascular cells expressing α (αSMA) to fibroblast growth factor 2 (FGF2) in vivo. We performed in vivo fate mapping by inducible Cre-loxP and experimental pulp injury in molars to induce reparative dentinogenesis. Our results demonstrate that early delivery of exogenous FGF2 to exposed pulp led to proliferative expansion of αSMA-tdTomato⁺ cells and their accelerated differentiation into odontoblasts. In vivo lineage-tracing experiments showed that the calcified bridge/reparative dentin in FGF2-treated pulps were lined with an increased number of Dspp⁺ odontoblasts and devoid of BSP⁺ osteoblasts. The increased number of odontoblasts derived from αSMA-tdTomato⁺ cells and the formation of reparative dentin devoid of osteoblasts provide in vivo evidence for the stimulatory effects of FGF signaling on odontoblast differentiation from early progenitors in dental pulp.

Oral Sciences PhD Program Enrollment, Graduates, and Placement: 1994 to 2016

For decades, dental schools in the United States have endured a significant faculty shortage. Studies have determined that the top 2 sources of dental faculty are advanced education programs and private practice. Those who have completed both DDS and PhD training are considered prime candidates for dental faculty positions. However, there is no national database to track those trainees and no evidence to indicate that they entered academia upon graduation. The objective of this study was to assess outcomes of dental school-affiliated oral sciences PhD program enrollment, graduates, and placement between 1994 and 2016. Using the American Dental Association annual survey of advanced dental education programs not accredited by the Commission on Dental Accreditation and data obtained from 22 oral sciences PhD programs, we assessed student demographics, enrollment, graduation, and placement. Based on the data provided by program directors, the average new enrollment was 33, and graduation was 26 per year. A total of 605 graduated; 39 did not complete; and 168 were still in training. Among those 605 graduates, 211 were faculty in U.S. academic institutions, and 77 were faculty in foreign institutions. Given that vacant budgeted full-time faculty positions averaged 257 per year during this period, graduates from those oral sciences PhD programs who entered academia in the United States would have filled 9 (3.6%) vacant faculty positions per year. Therefore, PhD programs have consistently generated only a small pipeline of dental school faculty. Better mentoring to retain talent in academia is necessary. Stronger support and creative funding plans are essential to sustain the PhD program. Furthermore, the oral sciences PhD program database should be established and maintained by dental professional organizations to allow assessments of training models, trends of enrollment, graduation, and placement outcomes.

Mineral trioxide aggregate improves healing response of periodontal tissue to injury in mice

BACKGROUND AND OBJECTIVE

Mineral trioxide aggregate (MTA) is a biomaterial used in endodontic procedures as it exerts beneficial effects on regenerative processes. In this study, we evaluate the effect of MTA on healing of periodontal ligament (PDL) and surrounding tissue, following injury, in a transgenic mouse model and on the differentiation of murine mesenchymal progenitor cells in vitro.

MATERIAL AND METHODS

We used an inducible Cre-loxP in vivo fate mapping approach to examine the effects of MTA on the contributions of descendants of cells expressing the αSMA-CreERT2 transgene (SMA9⁺ ) to the PDL and alveolar bone after experimental injury to the root furcation on the maxillary first molars. Col2.3GFP was used as a marker to identify mature osteoblasts, cementoblasts and PDL fibroblasts. The effects of MTA were examined 2, 17 and 30 days after injury and compared histologically with sealing using an adhesive system. The effects of two dilutions of medium conditioned with MTA on proliferation and differentiation of mesenchymal progenitor cells derived from bone marrow (BMSC) and periodontal ligament (PDLC) in vitro were examined using the PrestoBlue viability assay, alkaline phosphatase and Von Kossa staining. The expression of markers of differentiation was assessed using real-time PCR.

RESULTS

Histological analyses showed better repair in teeth restored with MTA, as shown by greater expansion of SMA9⁺ progenitor cells and Col2.3GFP⁺ osteoblasts compared with control teeth. We also observed a positive effect on differentiation of SMA9⁺ progenitors into osteoblasts and cementoblasts in the apical region distant from the site of injury. The in vitro data showed that MTA-conditioned medium reduced cell viability and osteogenic differentiation in both PDLC and BMSC, indicated by reduced von Kossa staining and lower expression of osteocalcin and bone sialoprotein. In addition, cultures grown in the presence of MTA had marked decreases in SMA9⁺ and Col2.3GFP⁺ areas as compared with osteogenic medium, confirming reduced osteogenesis.

CONCLUSION

MTA promotes regeneration of injured PDL and alveolar bone, reflected as contribution of progenitors (SMA9⁺ cells) into osteoblasts (Col2.3GFP⁺ cells). In vitro, MTA-conditioned medium fails to promote osteogenic differentiation of both PDLC and BMSC.

FGF Signaling Prevents the Terminal Differentiation of Odontoblasts

Members of the fibroblast growth factor (FGF) family play essential and important roles in primary and reparative dentinogenesis, with conflicting results regarding their effects on odontoblast differentiation. Our recent studies showed that the effects of FGF2 on cells in odontoblast lineage were stage-specific and depended on the stage of cell maturity. Continuous exposure of pulp cells to FGF2 inhibited odontoblast differentiation, whereas early and limited exposure of pulp cells to FGF2 resulted in marked increases in odontoblast differentiation. The purpose of this study was to evaluate the cellular and molecular mechanisms regulating the inhibitory effects of FGF2 on odontoblast differentiation. To do so, we examined the effects of the addition of FGF2 during the differentiation/mineralization phase of the in vitro growth of pulp cultures derived from a series of green fluorescent protein reporter transgenic mice that display stage-specific activation of transgenes during odontoblast differentiation. Our results showed that this treatment first stimulated the differentiation of remaining progenitors in pulp cultures into functional odontoblasts but prevented their differentiation into mature odontoblasts. In addition, this treatment inhibited expression of markers of osteogenesis. Furthermore, we demonstrated that the inhibitory effects of FGF2 on odontoblast differentiation were mediated through activation of FGFR/MEK/Erk1/2 signaling and downregulation of bone morphogenetic protein signaling, with negative and positive roles in the expression of Dmp1 and Dspp, respectively, during the advanced stage of odontoblast differentiation.

Multidisciplinary management of a patient with van der Woude syndrome: A case report

•

We described the orthodontic treatment of a girl diagnosed with VWS.

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Multidisciplinary techniques resulted in satisfactory outcomes.

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Genetic testing determined a known putative splice site mutation.

Introduction

Van der Woude syndrome (VWS) is the most frequent form of syndromic cleft lip and palate (SCLP) accounting for 2% of all patients with CLP.

Case presentation

We describe the orthodontic treatment of a girl diagnosed with VWS referred by her family dentist for her cosmetic concerns.

Discussion

Comprehensive orthodontic treatment, secondary bone graft, distraction osteogenesis (for a deficient maxilla), secondary palatoplasty and excision of lower lip pits, as well as orthodontic and prosthetic procedures may provide a satisfactory outcome. Genetic testing showed a known putative splice site mutation (c.174 + 1 G/A) as the prime cause of VWS in our patient and her family.

Conclusion

SCLP has significant effects on facial aesthetics and the psychosocial status. Parents should be assessed and counseled appropriately. This condition is treatable in the absence of life threatening systemic anomalies. An interdisciplinary team approach is advocated.

αSMA-Expressing Perivascular Cells Represent Dental Pulp Progenitors In Vivo

The goal of this study was to examine the contribution of perivascular cells to odontoblasts during the development, growth, and repair of dentin using mouse molars as a model. We used an inducible, Cre-loxP in vivo fate-mapping approach to examine the contributions of the descendants of cells expressing the αSMA-CreERT2 transgene to the odontoblast lineage. In vivo lineage-tracing experiments in molars showed the contribution of αSMA-tdTomato⁺ cells to a small number of newly formed odontoblasts during primary dentinogenesis. Using an experimental pulp exposure model in molars to induce reparative dentinogenesis, we demonstrate the contribution of αSMA-tdTomato⁺ cells to cells secreting reparative dentin. Our results demonstrate that αSMA-tdTomato⁺ cells differentiated into Col2.3-GFP⁺ cells composed of both Dspp⁺ odontoblasts and Bsp⁺ osteoblasts. Our findings identify a population of mesenchymal progenitor cells capable of giving rise to a second generation of odontoblasts during reparative dentinogenesis. This population also makes a small contribution to odontoblasts during primary dentinogenesis.

Enhanced Dentinogenesis of Pulp Progenitors by Early Exposure to FGF2

Members of the fibroblast growth factor (FGF) family play essential and important roles in primary and reparative dentinogenesis. Although there appears to be a general agreement on the effects of FGF signaling on the proliferation of pulp cells, there are conflicting results regarding its effects on odontoblast differentiation. We recently examined the effects of continuous exposure of dental pulp cells to FGF2 and showed that the effects of FGF2 on differentiation of progenitor cells into odontoblasts were stage specific and dependent on the stage of cell maturity. The purpose of this study was to gain further insight into cellular and molecular mechanisms regulating the stimulatory effects of FGF2 on odontoblast differentiation. To do so, we examined the effects of early and limited exposure of pulp cells from a series of green fluorescent protein (GFP) reporter transgenic mice that display stage-specific activation of transgenes during odontoblast differentiation to FGF2. Our results showed that early and limited exposure of pulp cells to FGF2 did not have significant effects on the extent of mineralization but induced significant increases in the expression of Dmp1 and Dspp and the number of DMP1-GFP(+) and DSPP-Cerulean(+) odontoblasts. Our results also showed that the stimulatory effects of FGF2 on odontoblast differentiation were mediated through FGFR/MEK/Erk1/2 signaling, increases in Bmp2, and activation of the BMP/BMPR signaling pathway. These observations show that early and limited exposure of pulp cells to FGF2 alone promotes odontoblast differentiation and provides critical insight for applications of FGF2 in dentin regeneration.

Evaluation of cytotoxic effects of Anbarnesa on fibroblast L929: Can it be used as a mouthwash?

AIMS

In Iranian traditional medicine Anbarnesa (derived from smoke from burning female donkey's stool) has been used to treat ulcers and inflammatory conditions like stomatitis and ear infections (otitis). We assess the properties of Anbarnesa as an alternative mouthwash.

MATERIALS AND METHODS

In this experimental study, Anbarnesa smoke was analyzed using aGC-mass device. The smoke collected was dissolved at different densities in propylene glycol and incubated in Dulbecco's modified Eagle's medium in direct contact with fibroblast cells. Assessment of cytotoxicity was done at 1, 24 and 72 h. Cell viability was measured by methyl thiazolyl tetrazolium test, and ELISA Reader machine was used to read the results. Data were analyzed using one-way ANOVA test.

RESULTS

The findings of this study showed Anbarnesa was nontoxic in 1/64, 1/128 and 1/256 dilutions. In 1/32 dilution, toxicity was seen after 72 h. In dilutions, 1/8 and 1/16 toxicity were seen in the 1(st) h.

CONCLUSION

According to the initial results of Anbarnesa may be used as an alternative mouthwash with fewer side-effects for plaque control and prevention of periodontal disease.

In vivo identification of periodontal progenitor cells

The periodontal ligament contains progenitor cells; however, their identity and differentiation potential in vivo remain poorly characterized. Previous results have suggested that periodontal tissue progenitors reside in perivascular areas. Therefore, we utilized a lineage-tracing approach to identify and track periodontal progenitor cells from the perivascular region in vivo. We used an alpha-smooth muscle actin (αSMA) promoter-driven and tamoxifen-inducible Cre system (αSMACreERT2) that, in combination with a reporter mouse line (Ai9), permanently labels a cell population, termed 'SMA9'. To trace the differentiation of SMA9-labeled cells into osteoblasts/cementoblasts, we utilized a Col2.3GFP transgene, while expression of Scleraxis-GFP was used to follow differentiation into periodontal ligament fibroblasts during normal tissue formation and remodeling following injury. In uninjured three-week-old SMA9 mice, tamoxifen labeled a small population of cells in the periodontal ligament that expanded over time, particularly in the apical region of the root. By 17 days and 7 weeks after labeling, some SMA9-labeled cells expressed markers indicating differentiation into mature lineages, including cementocytes. Following injury, SMA9 cells expanded, and differentiated into cementoblasts, osteoblasts, and periodontal ligament fibroblasts. SMA9-labeled cells represent a source of progenitors that can give rise to mature osteoblasts, cementoblasts, and fibroblasts within the periodontium.

A feasibility study for the analysis of reparative dentinogenesis in pOBCol3.6GFPtpz transgenic mice

AIM

To examine the feasibility of using the pOBCol3.6GFPtpz [3.6-green fluorescent protein (GFP)] transgenic mice as an in vivo model for studying the biological sequence of events during pulp healing and reparative dentinogenesis.

METHODOLOGY

Pulp exposures were created in the first maxillary molar of 12-16-week-old 3.6-GFP transgenic mice with CD1 and C57/Bl6 genetic background. Direct pulp capping on exposed teeth was performed using mineral trioxide aggregate followed by restoration with a light-cured adhesive system (AS) and composite resin. In control teeth, the AS was placed in direct contact with the pulp. Animals were euthanized at various time points after pulp exposure and capping. The maxillary arch was isolated, fixed and processed for histological and epifluorescence analysis to examine reparative dentinogenesis.

RESULTS

Analysis of teeth immediately after pulp exposure revealed absence of odontoblasts expressing 3.6-GFP at the injury site. Evidence of reparative dentinogenesis was apparent at 4 weeks in 3.6-GFP mice in CD1 background and at 8 weeks in 3.6-GFP mice with C57/Bl6 background. The reparative dentine with both groups contained newly formed atubular-mineralized tissue resembling a dentine bridge and/or osteodentine that was lined by cells expressing 3.6-GFP as well as 3.6-GFP expressing cells embedded within the atubular matrix.

CONCLUSION

This study was conducted in a few animals and did not allow statistical analysis. The results revealed that the 3.6-GFP transgenic animals provide a unique model for direct analysis of cellular and molecular mechanisms of pulp repair and tertiary dentinogenesis in vivo. The study also shows the effects of the capping material and the genetic background of the mice in the sequence and timing of reparative dentinogenesis.

Characterization of progenitor cells in pulps of murine incisors

The continuous growth of rodent incisors requires the presence of stem cells capable of generating ameloblasts and odontoblasts. While epithelial stem cells giving rise to ameloblasts have been well-characterized, cells giving rise to the odontoblasts in incisors have not been fully characterized. The goal of this study was to gain insight into the potential population in dental pulps of unerupted and erupted incisors that give rise to odontoblasts. We show that pulps from unerupted incisors contain a significant mesenchymal-stem-cell (MSC)-like population (cells expressing CD90+/CD45-, CD117+/CD45-, Sca-1+/CD45-) and few CD45+ cells. Our in vitro studies showed that these cells displayed extensive osteo-dentinogenic potential, but were unable to differentiate into chondrocytes and adipocytes. Dental pulps from erupted incisors displayed increased percentages of CD45+ and decreased percentages of cells expressing markers of an MSC-like population. Despite these differences, pulps from erupted incisors also displayed extensive osteo-dentinogenic potential and inability to differentiate into chondrocytes and adipocytes. These results provide evidence that continuous generation of odontoblasts and dentin on the labial and lingual sides of unerupted and erupted incisors is supported by a progenitor population and not multipotent MSCs in the dental pulp.

Obesity and the metabolic syndrome in a student cohort from Southern Italy

BACKGROUND AND AIM

Cardiovascular (CV) risk factors present in childhood predict future CV events. Few data regarding the metabolic syndrome (MS) prevalence are available in adolescents from Mediterranean areas where obesity is becoming a social emergency. This study presents data of MS prevalence in a student cohort from southern Italy.

METHODS AND RESULTS

1629 students between 7 and 14 years of age underwent anthropometric measurements and a blood sample was obtained to assess biochemical parameters. MS risk factors were calculated based on age and gender adjusted percentiles of parameter distributions. MS prevalence rate was 0.022 using paediatric, age-adjusted criteria; the rate increased to 0.029 using a 90th percentile criteria for fasting blood glucose instead of >100mg/dL. Using the criteria issued by the International Diabetes Federation the MS prevalence rate dropped to 0.005. The exploratory factor analysis identified four factors: age/fat related, lipids, blood pressure and blood glucose. Family history of type 2 diabetes mellitus was associated with triglyceride [OR=1.55 (1.0-2.3)] and BMI [OR=1.71 (1.2-2.4)] but not to blood glucose by logistic regression analysis.

CONCLUSIONS

In a student cohort from Southern Italy, obesity is associated with the features of MS.

Mandibular phenotype of p20C/EBPbeta transgenic mice: Reduced alveolar bone mass and site-specific dentin dysplasia

CCAAT enhancer binding proteins (C/EBP) comprise a family of basic-leucine zipper transcription factors that regulate cellular differentiation and function. To determine the role of C/EBP transcription factors in osteoblasts and odontoblasts, we generated a transgenic (TG) mouse model with Co1a1 (pOBCol3.6) promoter-targeted expression of a FLAG-tagged dominant negative C/EBP isoform, p20C/EBPbeta (previously LIP). Two of the four transgenic lines presented with abnormalities in the developing incisors, including breakage, overgrowth, and malocclusion. Histological examination revealed that the amount of alveolar bone was reduced in TG compared to wild-type (WT) mice. By microcomputed tomography (microCT), the bone volume fraction of the mandible was reduced at the level of the first and third molars, demonstrating a severe mandibular osteopenia. The lingual dentin morphology of TG incisors differed dramatically from WT. Labial dentin (enamel side) showed normal thickness and tubular dentin structure, whereas the lingual dentin was thinner (25-30% of WT at the alveolar crest) with an amorphous globular structure characteristic of dentin dysplasia. FLAG immunostaining was seen in both lingual and labial odontoblasts, indicating that the site-specific defect was not due to a lack of labial transgene expression. Northern blot analysis demonstrated reduced osteocalcin expression in TG mandibles, while bone sialoprotein was increased, consistent with prior results in calvariae and long bones. Dental sialophosphoprotein, a marker of the odontoblast lineage whose absence causes dentin dysplasia, was modestly reduced in TG mice by Northern blot and in situ hybridization analysis. By fluorescence microscopy, pOBCol2.3-GFP, a marker of the odontoblast lineage, was expressed in both labial and lingual odontoblasts, although GFP-marked lingual odontoblasts were more flattened than WT cells. Moreover, GFP-positive processes in the lingual dentin tubules were truncated and less organized than those in WT dentin. MicroCT analysis showed reduced tissue density in the lingual dentin. These data suggest that C/EBP transcription factors may be involved in the regulation of odontoblast polarization and dentin matrix production.

Analysis of developmental potentials of dental pulp in vitro using GFP transgenes

BACKGROUND

In recent years there has been increasing progress in identifying stem cells from adult tissues and their potential application for tooth replacement/regeneration. Our previous in vivo studies show that pOBCol3.6GFP and pOBCol2.3GFP transgenic animals provide a unique model to gain insight into progenitor/stem cells in the dental pulp capable of giving rise to odontoblasts.

OBJECTIVES

To characterize the behavior of dental pulp cells derived from pOBCol3.6GFP animals in vitro.

EXPERIMENTAL DESIGN

Primary cultures were established from the coronal portions of the pulps isolated first molars from 5-day-old pOBCol3.6GFP heterozygous mice and grown for 21 days. In these cultures proliferation, clonogenic capacity, activation of 3.6-GFP and mineralization were examined.

RESULTS

Our observations show that dental pulp cells derived from 3.6-GFP contain a population of proliferative, clonogenic cells with the ability to mineralize. We also show the stage specific activation/upregulation of 3.6-GFP in primary cultures derived from dental pulp. In these cultures, expression of Col1a1-3.6-GFP occurs prior to the appearance of mineralized nodules and is unregulated in mineralized nodules.

CONCLUSIONS

Col1a1-GFP transgenes appear to fulfill many of the requirements of a marker gene for cell lineage studies in intact tooth and primary cultures derived from dental pulp.

Visualizing levels of osteoblast differentiation by a two-color promoter-GFP strategy: Type I collagen-GFPcyan and osteocalcin-GFPtpz

A 3.9 kb DNA fragment of human osteocalcin promoter and 3.6 kb DNA fragment of the rat collagen type1a1 promoter linked with visually distinguishable GFP isomers, topaz and cyan, were used for multiplex analysis of osteoblast lineage progression. Three patterns of dual transgene expression can be appreciated in primary bone cell cultures derived from the transgenic mice and by histology of their corresponding bones. Our data support the interpretation that strong pOBCol3.6GFPcyan alone is found in newly formed osteoblasts, while strong pOBCol3.6GFPcyan and hOC-GFPtpz are present in osteoblasts actively making a new matrix. Osteoblasts expressing strong hOC-GFPtpz and weak pOBCol3.6GFPcyan are also present and may or may not be producing mineralized matrix. This multiplex approach reveals the heterogeneity within the mature osteoblast population that cannot be appreciated by current histological methods. It should be useful to identify and isolate populations of cells within an osteoblast lineage as they progress through stages of differentiation.

Dentin matrix protein 1 expression during osteoblastic differentiation, generation of an osteocyte GFP-transgene

Our previous studies have demonstrated that promoter-green fluorescent protein (GFP) transgenes can be used to identify and isolate populations of cells at the preosteoblastic stage (pOBCol3.6GFP) and at the mature osteoblastic stage (pOBCol2.3GFP) in living primary bone cell cultures. This strategy forms the basis for appreciating the cellular heterogeneity of lineage and relating gene function to cell differentiation. A weakness of this approach was the lack of a selective marker for late osteoblasts and mature osteocytes in the mineralized matrix. In this study, we have examined the expression of DMP-1 mRNA in murine marrow stromal and calvarial osteoblast cultures, and in bone, and calvaria in vivo. Furthermore, we have generated transgenic mice utilizing a mouse DMP1 cis-regulatory system to drive GFP as a marker for living osteocytes. Transgene expression was directed to mineralized tissues and showed a high correlation with the expression of the endogenous gene. Osteocyte-restricted expression of GFP was observed in histological sections of femur and calvaria and in primary cell cultures. Generation of this transgenic model will facilitate studies of gene expression and biological functions in these terminally differentiated bone cells.

Col1a1-GFP transgene expression in developing incisors

Previous studies have shown that terminal differentiation of odontoblasts is accompanied by dramatic increases in type I collagen synthesis. Recently transgenic mice in which green fluorescent protein (GFP) expression is under the control of the rat 3.6 (pOBCol3.6GFPtpz) and 2.3 (pOBCol2.3GFPemd) Col1a1 promoter fragments were generated. Our analysis of these GFP-expressing transgenic mice shows that the 2.3-kb promoter fragment directs strong expression of GFP only to bones and teeth, whereas the 3.6-kb fragment of promoter directs strong expression of GFP in bone and tooth, as well as in other type I collagen producing tissues. Our observations of incisors in these transgenic mice show high levels of GFP expression in functional odontoblasts and in differentiated osteoblasts. These observations show that expression of GFP reporter genes closely follow the patterns of expression of alpha 1(I) collagen in various tissues including odontoblasts.

Directing the expression of a green fluorescent protein transgene in differentiated osteoblasts: comparison between rat type I collagen and rat osteocalcin promoters

The osteocalcin (OC) and a 2.3 kb fragment of the collagen promoter (Col2.3) have been used to restrict transgenic expression of a variety of proteins to bone. Transgenic mice carrying a green fluorescent protein (GFP) gene driven by each promoter were generated. Strong GFP expression was detected in OC-GFP mice in a few osteoblastic cells lining the endosteal bone surface and in scattered osteocytes within the bone matrix in long bones from 1-day-old to 6-month-old transgenic animals. Similar findings were noted in the forming tooth in which only individual odontoblasts expressed GFP without detectable expression from the dental pulp. This limited pattern of OC-GFP-positive cells contrasts with the uniform expression in the Col2.3GFP mice in which large proportion of osteoblasts, odontoblasts, and osteocytes strongly expressed the transgene. To assess transgene expression during in vitro differentiation, marrow stromal cell and neonatal calvarial osteoblast cultures were analyzed. The activity of both transgenes was restricted to mineralized nodules but the number of positive cells was lower in the OC-GFP-derived cultures. The different temporal and spatial pattern of each transgene in vivo and in vitro reveals potential advantages and disadvantages of these two transgene models.

Regulation of mandibular growth and morphogenesis

The development of the vertebrate face is a dynamic process that starts with the formation of facial processes/prominences. Facial processes are small buds made up of mesenchymal masses enclosed by an epithelial layer that surround the primitive mouth. The 2 maxillary processes, the 2 lateral nasal processes, and the frontonasal processes form the upper jaw. The lower jaw is formed by the 2 mandibular processes. Although the question of the embryonic origin of facial structures has received considerable attention, the mechanisms that control differential growth of the facial processes and patterning of skeletal tissues within these structures have been difficult to study and still are not well-understood. This has been partially due to the lack of readily identifiable morphologically discrete regions in the developing face that regulate patterning of the face. Nonetheless, in recent years there has been significant progress in the understanding of the signaling network controlling the patterning and development of the face (for review, see Richman et al., 1991; Francis-West et al., 1998). This review focuses on current understanding of the processes and signaling molecules that are involved in the formation of the mandibular arch.

Morphogenesis of the medial region of the developing mandible is regulated by multiple signaling pathways

Experimental evidence indicates that the mandibular primordia are specified as at least two independent functional regions: two large lateral (proximal) regions where morphogenesis is dependent on FGF-8 signaling, and a small medial region where morphogenesis is independent of FGF-8 and dependent on other signals. The patterns of expression of multiple signaling molecules and regulatory genes in the epithelium and mesenchyme of the medial region suggest that the regulatory hierarchies controlling morphogenesis of the medial region of the developing mandible are complex and involve multiple pathways. Recent genetic studies indicate that the 'ET-1-dHAND-Msx1 pathway' constitutes one of the genetic pathways involved in outgrowth and morphogenesis of the medial region. Functional studies in chick mandible suggest that FGFs (other then FGF-8) and BMPs are also part of signaling pathways that regulate morphogenesis of the medial region. These studies suggest that in the medial region of the developing mandible, FGF-mediated signaling is involved in growth-promoting interaction, whereas BMP-mediated signaling is involved in chondrogenesis.

Effects of BMP-7 on mouse tooth mesenchyme and chick mandibular mesenchyme

BMP-7 is a member of the BMP family of signaling molecules that are thought to play key roles in mediating inductive events during embryogenesis. In the present study the possible roles of BMP-7 in mediating inductive events during the initiation phase of odontogenesis and mandibular morphogenesis were investigated. To do so, we have examined the effects of agarose beads soaked in recombinant BMP-7 on E11 mouse molar-forming mesenchyme and stage 23 chick mandibular mesenchyme, and analyzed the patterns of expression of Bmp-7 in developing mouse and chick first branchial arches. Beads releasing BMP-7 induced a translucent zone, cellular proliferation, and expression of Msx-1, Msx-2, and Bmp-4 in molar-forming mesenchyme after 24 hr. The effects of BMP-7 on molar-forming mesenchyme are similar to the effects of BMP-4 and are consistent with their overlapping patterns of expression in the thickened epithelium of the early developing tooth buds, which is suggestive of cooperative and/or redundant roles of BMPs in mediating the inductive interactions during the early stages of odontogenesis. Our studies in the developing chick mandible showed that Bmp-7 is expressed in the mandibular epithelium. In the absence of mandibular epithelium, BMP-7 beads maintained cell proliferation and Msx expression in the medial mandibular mesenchyme and were able to induce cell proliferation, cell death, and Msx expression in the lateral chick mandibular mesenchyme. The effects of BMP-7 on the expression of Msx genes in lateral chick mandibular mesenchyme, although different from the effects of lateral mandibular epithelium, are similar to the effects of epithelium from the medial region where multiple Bmps are expressed. We also showed that laterally placed BMP-7 beads induced ectopic expression of Msx genes and changes in the development of posterior skeletal elements in the maxillary and mandibular arches. However, despite its proliferative effects on mandibular mesenchyme, BMP-7 did not support the directional outgrowth of the mandible. These observations suggest that epithelial-mesenchymal interactions in the medial region of the mandibular arch regulating directional outgrowth of the mandibular mesenchyme are mediated by cooperative interactions between BMPs and other growth factors. Our observations also indicated that EGF, another growth factor implicated in mediating epithelial-mesenchymal interactions in the initiation phase of odontogenesis and morphogenesis of the developing mandible, induces an extensive translucent zone and cellular proliferation in the E11 mouse molar-forming mesenchyme and stage 23 chick mandibular mesenchyme. However, in contrast to BMPs, EGF did not induce Msx-1, Msx-2, and Bmp-4, but modulated the effects of BMPs on the expression of Msx-1 and Msx-2 in these mesenchymes. Our combined data suggest that BMP-7 is a component of the signaling network mediating epithelial-mesenchymal interactions during the initiation phase of odontogenesis and morphogenesis of the mandibular arch.

Odontogenic epithelium induces similar molecular responses in chick and mouse mandibular mesenchyme

Previous observations have shown that, during the initiation phase of odontogenesis, signals from mouse odontogenic epithelium can elicit teeth in non-odontogenic but neural crest-derived mesenchyme isolated from ectopic sites including chick mandibular mesenchyme. In the present study the formation of ectopic tooth buds and dental mesenchyme in chick mandibular mesenchyme was examined using heterospecific recombinations between E11 mouse odontogenic epithelium and stage 23 chick lateral mandibular mesenchyme. Both morphological criteria and chick-specific probes for Msx-1, Msx-2, and Bmp-4 mRNAs were used as markers for early dental mesenchyme. Our results demonstrated that interactions of mouse odontogenic epithelium with chick mandibular mesenchyme induce early changes in the chick mandibular mesenchyme including the appearance of a translucent zone, cell proliferation, and induction of expression of Msx-1, Msx-2, and Bmp-4, which have been shown to be associated with the formation of dental mesenchyme. In addition, tooth bud-like structures that resemble E13 tooth buds in vivo both morphologically and in their patterns of gene expression formed after 6 days in the heterospecific recombinations. The tooth bud-like structures consist of invaginated mouse mandibular epithelium and condensed chick mandibular mesenchyme expressing high levels of Msx-1 and Bmp-4, but undetectable levels of Msx-2. Unlike the induction of Msx-1, Msx-2, and Bmp-4 in the underlying mesenchyme, which is specific for signals derived from odontogenic epithelium, the induction of a translucent zone and cellular proliferation in the underlying mesenchyme may be related to the growth-promoting potential of embryonic epithelia and not be specific to signals derived from the odontogenic epithelium. Similar to mouse odontogenic epithelium, agarose beads soaked in recombinant BMP-4 induced a translucent zone, cellular proliferation, and expression of Msx-1, Msx-2, and Bmp-4 in chick mandibular mesenchyme after 24 hours. These observations together showed that avian mandibular mesenchyme has odontogenic potential that is expressed upon interactions with inductive signals from mouse odontogenic epithelium. Similar to odontogenesis in vivo, formation of dental mesenchyme in chick mandibular mesenchyme is mediated by the activation of Msx-1, Msx-2, and Bmp-4.

Functional and morphologic evidence of the presence of tissue-plasminogen activator in vascular nerves: implications for a neurologic control of vessel wall fibrinolysis and rigidity

Tissue plasminogen activator (t-PA) is expressed by hypothalamic and peripheral sympathetic neurons. The sympathetic axons that permeate artery walls have not been investigated as possible sources of intramural t-PA. The plasmin produced by such a system would locally activate both fibrinolysis and matrix metalloproteinases that regulate arterial collagen turnover. To assess this neural t-PA production, we investigated the capacity of rat cervical sympathetic ganglion neurons to synthesize and release t-PA, and the expression of the enzyme in carotid artery and the iris-choroid microvascular tissues that receive the ganglion axon distribution. Functional studies confirmed that (i) the ganglion neuron cell bodies synthesize t-PA mRNA, (ii) cultured ganglion carotid artery and iris-choroid microvascular explants predominantly release t-PA rather than urokinase, (iii) microvascular tissues release approximately 20 times more t-PA per milligram than carotid explants (which accords with the higher innervation density of small vessels), and (iv) removal of the endothelium did not cause major reductions in the t-PA release from carotid and microvascular explants. Immunolocalization studies then confirmed a strong expression of the enzyme within the ganglion axons, the carotid adventitia that receives these axons, and the predominantly sympathetic axon terminals in the iris-choroid microvasculature. These data indicate the existence of a previously undescribed system for the delivery of neural t-PA to vessel walls. The intramural production of plasmin induced by this system represents a novel principle for the regulation of arterial matrix flexibility, especially in the media of densely innervated small arteries and resistance arterioles involved in the pathogenesis of stroke, hypertension, and vascular aging. Thus, the data suggest an important new interface between neuroscience and vascular biology that merits further exploration.

EGF does not induce Msx-1 and Msx-2 in dental mesenchyme

Previous heterospecific tissue recombinations indicate that mandibular epithelium exerts the first known inductive signal for odontogenesis in mouse embryos. BMP-4 and EGF are two growth factors implicated as signaling molecules mediating the initial inductive epithelial-mesenchymal interactions during odontogenesis. The purpose of the present study was to examine and compare the effects of these growth factors and mouse mandibular epithelium on expression of Msx-1 and Msx-2 genes in molar-forming mesenchyme. Agarose beads soaked in growth factors or pieces of mouse mandibular epithelium (E11) were placed in contact with E11 molar-forming mesenchyme and cultured for 24 h. Whole-mount in situ hybridization analysis revealed that, in contrast to mouse mandibular epithelium and BMP-4-releasing beads, EGF-releasing beads did not induce the expression of Msx-1 and Msx-2 in E11 molar-forming mesenchyme. These observations suggest that whereas BMP-4 may be involved in activation of Msx-1 and Msx-2 in the underlying mesenchyme, EGF may regulate events involved in the formation of dental lamina.

Downregulation of Msx-2 expression results in chondrogenesis in the medial region of the avian mandible

Homeobox-containing genes are thought to be regulators of pattern formation during vertebrate development. We have previously characterized regions in the developing chick mandible expressing either Msx-1 or Msx-2 in terms of their chondrogenic potential, rates of cell proliferation, and their correlation with regions of cell death. These experiments suggest that Msx-1 may be involved in outgrowth of the mandibular arch, and Msx-2 may be involved in delineating the non-chondrogenic region of the medial part of the mandibular arch. To further examine the possibility that expression of Msx-2 may be involved in preventing chondrogenesis in the medial region, mandibular arch explants from stage 23 chick embryos were cultured for 4 days in media in the absence of serum but in the presence of 20-30 microM Msx-2 sense or antisense oligonucleotides (18 mers). In explants grown in either control media or with the sense oligonucleotide two rods of cartilage separated by a cartilage free area located in the medial region of the mandible were formed. In explants treated with Msx-2 antisense oligonucleotide cartilage formation was observed in the medial region of the mandible resulting in the fusion of the two bilateral rods at the midline. These results suggest a negative relationship between Msx-2 expression and chondrogenesis in the medial region of the developing mandible.

Tenascin-C is associated with early stages of chondrogenesis by chick mandibular ectomesenchymal cells in vivo and in vitro

Tenascin-C is an extracellular matrix protein thought to be involved in skeletogenesis. We have examined the distribution of tenascin-C in the developing chick mandibular arch between stages 18-36, and during in vitro chondrogenesis of mandibular ectomesenchymal cells in micromass cultures using a probe and antibody that correspond to the portion of the tenascin-C transcript conserved in all of the three known chick splice variants. In situ hybridization and immunohistochemical analyses demonstrate that tenascin-C is predominantly expressed in the condensing mesenchyme of developing cartilage, and in the perichondrium of differentiated cartilage. Tenascin-C expression, although detected in differentiating chondroblasts, was not detected in differentiated cartilage. Tenascin-C was also expressed in the developing membranous bones. In addition, the expression of tenascin-C transcripts during in vitro chondrogenesis of mandibular ectomesenchymal cells in micromass cultures was compared to the patterns of expression of aggrecan core protein and alpha 1(I) collagen transcripts. Our in situ hybridization analyses of micromass cultures demonstrate the expression of tenascin-C and aggrecan core protein mRNAs by pre-chondrogenic aggregates in the 1-day cultures and by chondroblasts in differentiating cartilage nodules in 2-day cultures. In 4- and 9-day cultures, the pattern of expression of tenascin-C mRNA was different from the patterns of expression of aggrecan core protein mRNA, and appeared to be more closely related to the expression of alpha 1(I) collagen mRNA. Aggrecan core protein mRNA was expressed by chondrocytes in cartilage nodules in 4- and 9-day cultures. On the other hand, tenascin-C and alpha 1(I) collagen mRNAs, in addition to being expressed in the loose connective tissues in the inter-nodular spaces, were predominantly expressed by the elongated, flattened, and fibroblast-like cells around the cartilage nodules. These results indicate that during the in vitro chondrogenesis of mandibular ectomesenchymal cells, expression of tenascin-C mRNA identifies chondrocytes in their early stages of differentiation. The patterns of expression of tenascin-C mRNA in 4- and 9-day cultures further suggest that tenascin-C is expressed in the perichondrium-like structures that form around the cartilage nodules in micromass cultures. Therefore, our in vitro studies, in agreement with our in vivo studies, suggest an association of tenascin-C with the initial or early stages of chondrogenesis in the chicken mandibular arch.

Experimental analysis of Msx-1 and Msx-2 gene expression during chick mandibular morphogenesis

Homeobox-containing genes are thought to be involved in regulating pattern formation in a variety of tissues during embryogenesis. We have examined the expression of the homeobox-related genes Msx-1 and Msx-2 during the development of the chick mandibular arch. Northern blot hybridization indicates that transcripts for both Msx-1 (1.6 Kb) and Msx-2 (3 Kb) are present in the mandibular arch as early as stage 18. The levels of both transcripts in the whole mandible decrease as cartilage is formed in vivo and in vitro. Using in situ hybridization, transcripts of Msx-1 were localized in high amounts to the mesenchyme of the mesial tips of the arches. Msx-2 transcripts were localized in high amounts to medial regions of the arches. Little or no hybridization of either probe was detected in the chondrogenic and myogenic regions of the arches. Transcripts of both genes were also excluded from calcified bone and cartilage. Our results further demonstrate that the mesial tip mesenchyme expressing Msx-1 includes areas of highly proliferative cells and has in vitro chondrogenic potential. The region of mesenchymal cells expressing the Msx-2 gene overlap with areas of developmentally programmed cell death which also contain very few proliferative cells and lack chondrogenic potential in vitro. These results are consistent with the possibility that Msx-1 may be involved in the outgrowth of the mandibular arch and Msx-2 may be involved in both developmentally programmed cell death and delineating the non-chondrogenic region of the medial part of the mandibular arch.

Enhancement of avian mandibular chondrogenesis in vitro in the absence of epithelium

The roles of mandibular epithelium in chondrogenesis and growth of mandibular mesenchyme were examined in organ cultures. Epithelium and mesenchyme were separated from the mandibular arches of chick embryos at stages before and after the onset of chondrogenesis in vivo (stages 18-28). Isochronic and heterochronic tissue recombinations were prepared. Removal of the mandibular epithelium resulted in reduced growth of the explants and enhanced chondrogenesis, resulting in increased levels of mRNAs for type II collagen and aggrecan. The presence of mandibular epithelium promoted cell division in loosely arranged undifferentiated tissue from the mandibular mesenchyme and resulted in increased levels of type I collagen mRNA. Enhanced chondrogenesis was also observed in the mesenchyme isolated with basement membrane and isolated mesenchyme grown within Matrigel. These findings suggest that mandibular epithelium has mitogenic and chondrogenic-inhibitory effects on the underlying mesenchyme that are stage independent. Furthermore, the chondrogenic-inhibitory effect of mandibular epithelium on the underlying mesenchymal cells is not mediated by basement membrane.

Stage-related chondrogenic potential of avian mandibular ectomesenchymal cells

We have examined the in vitro stage-related chondrogenic potential of avian mandibular ectomesenchymal cells using micromass cultures. Our results indicate that mandibular ectomesenchymal cells as early as stage 16, soon after the formation of the mandibular arches and well before the initiation of in vivo chondrogenesis, have chondrogenic potential which is expressed in micromass culture. There is an increase in the total area of the cultures occupied by cartilage when cells from increasing stages of development are used. The nodular pattern of chondrogenesis in these cultures indicates that mandibular ectomesenchymal cells are a heterogenous population from the time of mandibular arch formation. In addition, we studied the temporal expression of the genes for extracellular matrix proteins during in vitro chondrogenesis and correlated the morphological changes with the pattern of gene expression. Low levels of type II collagen mRNA are present in the cultures prior to detection of any stainable cartilage matrix and increase 5 fold just before the onset of chondrogenesis in vitro. On the other hand mRNA for cartilage proteoglycan core protein was not detected until the second day of culture when stainable cartilage matrix was present and progressively increased thereafter. Messenger RNA for type I collagen was present at the time of initiation of cultures and continuously increased during the culture period. Our experiments also indicated that embryonic epithelia can inhibit the in vitro chondrogenesis of mandibular ectomesenchymal cells and that the inhibitory effect of embryonic epithelia is independent of its age and site of origin.

Temporal and spatial expression of genes for cartilage extracellular matrix proteins during avian mandibular arch development

We have examined the temporal expression of genes for extracellular matrix proteins (type I collagen, type II collagen, and the cartilage specific proteoglycan core protein) during the development of the avian mandibular arch. We detected low levels of type II collagen mRNA in the mandibular arch as early as stage 15. Type II collagen mRNA remained low but increased slightly as development progressed from stage 15 to stage 25. More dramatic increases occurred after stage 25 coincident with overt chondrogenesis. In contrast, mRNA for the core protein of cartilage specific proteoglycan was not detected prior to the onset of chondrogenesis, appeared at stage 25, and increased thereafter. Type I collagen mRNA was also present as early as stage 15 and dramatically increased after stage 28/29, coincident with initiation of osteogenesis. Using in situ hybridization, we found that type II collagen mRNA became detectable in the center of the mandible around stage 24/25 coincident with the initiation of chondrogenesis. At later stages (26-32) type II collagen mRNA was localized in the cartilaginous rudiment. The pattern of hybridization observed with the proteoglycan core protein probe at later stages of development was essentially identical to that observed with the type II collagen probe. In contrast, the probe for the alpha 1 (I) collagen mRNA was localized over the perichondrium, over differentiated bone, and in areas within the mandibular arch where bone formation had been initiated.

Using magnostrictive metal as a pump for biomedical application

A new theory of pumping fluids, including blood, has been developed using magnetostrictive technology. This new pump uses the magnetostrictive material known as Terfenol-DTM. A magnetic field is imposed on the Terfenol in periodic pulses causing it to expand and then relax to its original state. The expansion and relaxation of the terfenol cause a smooth, continuous flow of fluid. This pump is currently being built and will be tested as a left ventricular assist device, totally implantable artificial heart, or both.

Assay of ATP-sulfurylase activity from rat liver by high-performance liquid chromatography

Alteration of proteoglycan composition is known to accompany morphogenesis. In many tissues one such alteration is the removal of hyaluronate and its replacement with a sulfated proteoglycan. Several mechanisms that could regulate this alteration have been studied leading to a hypothesis that the increase in the sulfated proteoglycan is regulated by controlling the activity of those enzymes involved in the activation of the sulfate. To measure any variations in these activities usually begins with a purification of the enzyme. However, this procedure is difficult to perform where tissue samples are difficult to obtain in large enough quantities. Therefore, the examination of an enzymatic activity when tissue samples are in short supply requires the development of methods for the assay of the specific activity after a minimum of purification. In this paper we report on the development of just such an assay for ATP-sulfurylase, the enzyme that catalyses the first step in the activation of sulfate. This method uses anion-exchange high-performance liquid chromatography and differs from a previously published procedure [F. A. Hommes and L. Moss, Anal. Biochem., 154 (1986) 100] in that the compounds are detected spectrophotometrically instead of radiometrically and also in that the ATP, ADP, AMP and their sulfated analogues, adenosine 5'-phosphosulfate and 3'-phosphoadenosine 5'-phosphosulfate, are separated isocratically. Studies performed with 35SO4(2-) were used to validate this new method. The separation of all these compounds has allowed us to develop a one-step, on-line assay procedure which can be performed on small samples of partially purified preparations. We have used this procedure to measure the activity of the ATP sulfurylase in extracts of rat liver and tongue. Our results indicated that the ATP-sulfurylase activity from rat liver was soluble with a pH optimum of 8.0. The identity of the reaction product was verified using radiolabeled sulfate as the substrate and recovering the radiolabel in the product. Preliminary kinetic studies with this method showed the sulfurylase activity to have an apparent Michaelis constant of 3 microM and a maximal velocity of 0.56 pmol/min per mg protein.