Papilla Formation Research Articles

The Barley Mutant emr1 was Identified in a Mutational Screen for Resistance Against Magnaporthe oryzae

Barley plants can be colonized by the fungus Magnaporthe oryzae , a pathogen initially known from rice plant cultivation. A mutational screen was performed in the barley mlo -genetic background which is, in comparison to wild-type MLO -genotypes, hypersusceptible against this fungus. This led to the identification of a mutant, referred to as emr1 (enhanced Magnaporthe resistance), that showed partially restored resistance. Disease symptoms on leaves of emr1 were significantly less severe than on mlo5 -genotypes but still more than on wt MLO -barley plants. Segregation analysis showed that emr1 was inherited as a single recessive trait. Insight into the mode of action of emr1 -dependent resistance against M. oryzae was gained by microscopic analysis. The results of these experiments revealed that mutant emr1 blocked penetration by M. oryzae by the formation of effective papillae in approximately half of all incidences. At about 30% of the interaction sites fungal growth was arrested effectively by an HR in the epidermal cell. Only a low frequency of fungal infection sites proceed into the mesophyll where fungal invasion resulted in the onset of a hypersensitive response (HR)-like cell death. Here, we report further evidence that barley shows a mesophyll HR in response to colonisation by M. oryzae. The possibility that the fungus turns this ostensible defence reaction to its own advantage and profits from the dead host tissue by switching to a necrotrophic lifestyle is discussed.

Saccharomyces cerevisiae SSD1 orthologues are essential for host infection by the ascomycete plant pathogens Colletotrichum lagenarium and Magnaporthe grisea

Fungal plant pathogens have evolved diverse strategies to overcome the multilayered plant defence responses that confront them upon host invasion. Here we show that pathogenicity of the cucumber anthracnose fungus, Colletotrichum lagenarium, and the rice blast fungus, Magnaporthe grisea, requires a gene orthologous to Saccharomyces cerevisiae SSD1, a regulator of cell wall assembly. Screening for C. lagenarium insertional mutants deficient in pathogenicity led to the identification of ClaSSD1. Following targeted gene replacement, appressoria of classd1 mutants retained the potential for penetration but were unable to penetrate into host epidermal cells. Transmission electron microscopy suggested that appressorial penetration by classd1 mutants was restricted by plant cell wall-associated defence responses, which were observed less frequently with the wild-type strain. Interestingly, on non-host onion epidermis classd1 mutants induced papilla formation faster and more abundantly than the wild type. Similarly, colonization of rice leaves by M. grisea was severely reduced after deletion of the orthologous MgSSD1 gene and attempted infection by the mutants was accompanied by the accumulation of reactive oxygen species within the host cell. These results suggest that appropriate assembly of the fungal cell wall as regulated by SSD1 allows these pathogens to establish infection by avoiding the induction of host defence responses.

Characterization of Reactions to Powdery Mildew (Podosphaera pannosa) in Resistant and Susceptible Rose Genotypes

AbstractFungal development of powdery mildew Podosphaera pannosa (Wallr.: Fr.) de Bary on rose leaves depends on constitutive or induced resistance mechanisms present in attacked rose genotypes. The relationship between fungal development and plant resistance was investigated microscopically on young greenhouse leaves of four rose genotypes with different levels of resistance: Rosa wichuraiana, R. laevigata anemoides and R. hybrida cultivars ‘Excelsa’ and ‘Gomery’. Induced plant reactions, hydrogen peroxide production and cross sections through infected leaves were examined. The variation in development of the fungus on these rose genotypes depended on the relative presence of normal haustoria, abnormal haustoria, induced cell reactions, papilla formation or physical barriers. Formation of papillae could arrest up to one third of the successful penetrations. Papillae formation was often succeeded by total cell reaction. Abnormal haustoria were detected as rudimentary haustoria, haustoria with abnormal shape or haustoria without extra haustorial matrix. Post‐haustorial cell reactions, with and without cell collapse, were detected. In non‐collapsed cells, appositions were directed to both cell wall and haustorium. This was followed by accumulation of non‐identified, probably antifungal compounds. Both single and multicell reactions occurred. Hydrogen peroxide was detected during papilla formation and induced cell reactions.

Morphological variation in the electric organ of the little skate (Leucoraja erinacea) and its possible role in communication during courtship

Skates discharge an electrical current too weak to be used for predation or defense, and too infrequent and irregular to be used for electrolocation. Additionally, skates possess a specialized sensory system that can detect electrical stimuli at the same strength at which they discharge their organs. These two factors are suggestive of a communicative role for the electric organ in skates, a role that has been demonstrated in similarly weakly electric teleosts (e.g., mormyrids and gymnotiforms). There is evidence that the sexual and ontogenetic variations in the electric organ discharge (EOD) in these other weakly electric fishes are linked to morphological variations in electric organs and the electrogenerating cells of the organs, the electrocytes. Little work has been done to examine possible sexual and ontogenetic variations in skate EODs or variations in the electrocytes responsible for those discharges. Electric organs and electrocyte morphology of male and female, and mature and immature little skates, Leucoraja erinacea, are characterized here. Female electric organs were bigger than male electric organs. This is suggestive of a sexually dimorphic EOD waveform or amplitude, which might be used as a sex-specific identification signal during courtship. The shapes of electrocytes that make up the organ were found to be significantly different between mature and immature individuals and, in some cases, posterior membrane surface area of the electrocytes increased at the onset of maturity due to the formation of membrane surface invaginations and papillae. This is evidence that the EOD of skates may differ in its waveform or amplitude or frequency between mature and immature skates, and act as a signal for readiness to mate. This study supports a communicative role during courtship for the weak electric organs of little skates, but studies that characterize skate EOD dimorphisms are needed to corroborate this speculation before conclusions can be drawn about the role the electric organ plays in communication during courtship.

Wnt signaling interacts with Shh to regulate taste papilla development

Wnt and Shh signaling pathways are critical for the development and maturation of many epithelial tissues. Both pathways have roles in stem cell maintenance, tissue development, and tumorigenesis. However, linkage between these pathways in mammalian systems had not been well established. Here, we report that Shh expression in fungiform papillae and formation of normal mature fungiform papillae depend on signaling through Wnt and beta-catenin. We observed that during fungiform papilla formation in mice, Shh and components of the Wnt/beta-catenin signaling pathway are expressed together in the developing placode. The elimination of Wnt/beta-catenin signaling in either Lef1 or Wnt10b knockout mice resulted in down-regulation of Shh expression. In addition, the size and number of fungiform papillae were greatly reduced in Lef1 knockout mice. By examining embryonic mouse tongues in culture we determined that activation of Wnt/beta-catenin signaling up-regulates Shh expression. We observed that blocking Shh signaling in cultured tongue explants enhanced papillae formation and was accompanied by an up-regulation of Wnt/beta-catenin signaling, indicating that Shh inhibits the Wnt/beta-catenin pathway. Exogenously added Shh suppressed expression of endogenous Shh and inhibited Wnt/beta-catenin signaling (assessed in TOPGAL mice), further implicating Shh as an inhibitor of the Wnt/beta-catenin pathway. Our observations indicate that Wnt/beta-catenin signaling and interactions between the Wnt and Shh pathways play essential roles in the development of fungiform papillae.

Choroid plexus papilloma with cytologic differential diagnosis - a case report

The cytopathologic features of choroid plexus papilloma observed in a one year-old male child are reported and compared with other paediatric central nervous system neoplasms. The cytologic features of choroid plexus papilloma are similar to those of normal choroid plexus and may be difficult to distinguish from those of a well differentiated papillary ependymoma and other tumours with papillae formation. However, the salient cytologic features of choroid plexus papilloma include well defined papillary clusters, monolayered sheets and isolated scattered tumour cells, comprising of cuboidal cells with uniform round or oval nuclei, evenly dispersed chromatin and moderate amount of cytoplasm. The utility of crush cytology in the rapid diagnosis of central nervous system tumours along with the differential diagnoses are highlighted in this report.

P-01 Hormones and Sexuality

The infection process was compared in interactions between Erysiphe graminis f.sp. hordei isolate A6 and two near-isogenic barley lines (the susceptible line P-01 and the resistant line P-02), and the non-host wheat. A low frequency of successful infections, measured as the percentage of germinated conidia forming primary haustoria, was detected in both susceptible (7·5%), and resistant (73%) barley isolines and wheat plants (223%). In all three types of plants, papilla formation around the sites of attempted penetration seems to be a general resistance factor and thus not the determining step for distinguishing between race-specific and non-host resistance. In wheat plants, further resistance was manifested early after penetration and characterized by hypersensitively reacting (HR) single cells, no or limited growth of elongating secondary hyphae and no visible sign of infection. The race-specific resistance of barley isoline P-02 occurred later after penetration, and was characterized by plant tissue necrosis and no or weak fungal sporulation. In the susceptible barley isoline P-01, successful infections resulted in heavily sporulating powdery mildew colonies. Putative guanidine compounds, indicated by the Sakaguchi test, occurred in papillae 4–5 h after inoculation and subsequently in HR cells too, and are apparently associated with the very early resistance responses in barley and wheat. The highly basic guanidine compounds, not identified previously in plant defence responses, were found to be bound to the cell wall, and referred to as “basic staining material”. Accumulation of polyphenolic substances and callose were demonstrated in papillae and HR cells of both barley and wheat. Lignification occurred in wheat, but did not occur or did so only minimally in barley.

Cellular basis of resistance to different formae speciales of Blumeria graminis in Hordeum chilense, wheat, and tritordeum and agroticum amphiloids

Tritordeum and agroticum amphiploids, derived from hybridization of Triticum species with Hordeum chilense or Agropyron cristatum, were assessed for resistance to Blumeria graminis. In glasshouse tests, all parental lines of H. chilense and A. cristatum showed complete resistance to wheat powdery mildew [Blumeria graminis f. sp. tritici] while all Triticum parents, except one, were highly susceptible. The amphiploids were all resistant to B. graminis f. sp. tritici, allowing the development of only a few sporulating colonies on leaves. Microscopic examination of host-cell responses to B. graminis revealed that resistance in H. chilense and amphiploids was attributable to two major factors: (i) a significant reduction in successful fungal penetration by rapid deposition of papillae in the host epidermal cell wall and (ii) a significant increase in frequency of death of penetrated epidermal cells. Papillae formation was associated with localized autofluorescence in host epidermal cells. Cell death prevented further fungal growth and differentiation for the establishment of biotrophy. Tritordeums showed both forms of resistance when tested with Blumeria graminis f. sp. hordei and Blumeria graminis f. sp. avenae. The tritordeum and agroticum amphiploids may offer novel sources of resistance to powdery mildew. They could be used either directly or as a bridge in genetic crosses to introgress resistance to powdery mildew into elite wheat breeding lines.

The Effects of Interimplant Distances on Papilla Formation and Crestal Resorption in Implants With a Morse Cone Connection and a Platform Switch: A Histomorphometric Study in Dogs

Implant esthetics have been the focus of attention for the last few years, and one of the most important points is the effect that interimplant distances can have on papilla formation and bone loss. The aim of this study was to evaluate the effect that distances of 1, 2, and 3 mm between implants after prosthetic restoration will have on crestal bone resorption (from the top of the implant to the bone crest [TI-BC]) and bone resorption (from the top of the implant to the first bone-to-implant contact TI-BIC) in two-stage implants used in a submerged and non-submerged protocol. The mandibular bilateral premolars of seven dogs were extracted, and after 12 weeks, each dog received eight implants. The implants were placed so that three interimplant contact points were created, with 1-mm (group 1), 2-mm (group 2), and 3-mm (group 3) distances constructed on each side. The sides and the position of the groups were randomly selected. After 12 weeks, the implants received metallic prostheses with 5 mm between the contact point and the bone crest. After 8 weeks more, the animals were sacrificed. The TI-BC was 0.20 and 0.18 mm for group 1, 0.15 and 0.14 mm for group 2, and 0.15 and 0.15 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BC was 0.16 mm for non-submerged and 0.16 mm for submerged implants. The TI-BIC was 0.32 and 0.30 mm for group 1, 0.19 and 0.21 mm for group 2, and 0.30 and 0.24 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BIC was 0.26 mm for non-submerged and 0.25 mm for submerged implants. There was no statistical difference for any of the parameters (analysis of variance [ANOVA]). Distances of 1, 2, and 3 mm between implants do not result in statistically significant differences on TI-BC and TI-BIC around submerged or non-submerged implants with a Morse cone connection and a platform switch.

Histochemical and genetic analysis of host and non‐host interactions of Arabidopsis with three Botrytis species: an important role for cell death control

SUMMARY Susceptibility was evaluated of host and non-host plants to three pathogenic Botrytis species: the generalist B. cinerea and the specialists B. elliptica (lily) and B. tulipae (tulip). B. tulipae was, unexpectedly, able to infect plant species other than tulip, and to a similar extent as B. cinerea. To study host and non-host interactions in more detail, the three Botrytis species were inoculated on Arabidopsis wild-types and 23 mutant genotypes. Disease development was monitored macroscopically by quantifying the lesion area and microscopically by bright-field and fluorescence microscopy following histochemical staining. B. cinerea and B. tulipae were very similar in their ability to infect the tested Arabidopsis genotypes, whereas B. elliptica caused disease only on a few Arabidopsis mutant genotypes. Arabidopsis mutants with a delayed or reduced cell death response were generally more resistant to Botrytis infection, whereas mutants in which cell death was accelerated were more susceptible. Differences in susceptibility between genotypes were generally gradual. Only the camalexin-deficient mutant pad3 was fully susceptible to all three Botrytis species. Cellular changes were monitored during compatible and incompatible interactions. The formation of papillae, the presence of lysosome-like vesicles and the intracellular accumulation of H(2)O(2) and nitric oxide were visualized in the infection zones using fluorescent probes. Based on histology and responses of Arabidopsis mutants, a model is proposed in which resistance against Botrytis, besides the production of camalexin, depends on the balance between cell death and survival.

Preprosthetic Periodontal Surgery in the Proximal Area With Modification of the COL Area: Results Following the Reestablishment of the Contact Point

Anatomic characteristics of interproximal areas are dependent on the anatomy, position, and proximal contact of adjacent teeth. The objective of this study was to investigate the influence of the reestablishment of the interproximal contact following the restorative alveolar interface (RAI) procedure on the interproximal gingival COL and formation of the interdental gingival papilla. Six mongrel dogs received bilateral apically positioned flaps, crown lengthening, and the RAI procedure on the maxillary fourth bicuspid and first molar. After 2 weeks, in a randomized manner, one side was prepared to receive metallic crowns and the opposite side remained as the control. The crowns were cemented at the 4-week postoperative period, and the dogs were sacrificed after another 4 weeks, totaling a period of 4 weeks with the full crowns in position and a total of 8 postoperative weeks. Histologic specimens were stained with hematoxylin and eosin and Mallory dyes. Sections 6 micro m thick were obtained in a bucco-lingual plane allowing ample visualization of the interproximal area. Clinical measurements revealed that, in the restored sides, four animals had complete fill of the interdental spaces with gingival papilla, whereas the other two dogs had a distance from the contact point to the tip of papilla varying from 0.02 to 0.021 mm. In the control group, papillae were totally reepithelialized with keratinized epithelium and a convex form. The epithelium completely covered the connective tissue and showed both epithelial projections and surface desquamation. On the test group, despite the presence of the prosthesis, the COL morphology modified by preprosthetic surgery was not altered, presenting a convex papilla with a triangular form and with a keratinized epithelium. Additional histologic characteristics were the same as found in the control group. Based on the results of this study, the reestablishment of the contact point does not revert what was obtained with the RAI procedure; the interproximal tissues remain convex and keratinized.

Influence of Interimplant Distance on Papilla Formation and Bone Resorption: A Clinical-radiographic Study in Dogs

Implant esthetics has been the focus of attention for the past decade, and one vital issue is the effect of interimplant distance on interimplant papilla formation and crestal bone loss. The aim of this study was to evaluate the effect of 1, 2, and 3 mm of interimplant distance on papilla formation and crestal resorption in submerged and nonsubmerged Ankylos implants after prosthetic restoration. Bilateral mandibular premolars of 7 dogs were extracted, and after 12 weeks each dog received 8 implants. Implants were placed so that 3 interimplant distances were created at 1 mm (group 1), 2 mm (group 2), and 3 mm (group 3). The sides and the position of the groups were randomly selected. Twelve weeks after placement, the implants received metallic prostheses that allowed 5 mm of space between the prosthetic contact point (CP) and the crestal bone (CB). After 8 weeks, the distance between the CP and the papilla (CP-P) and the gingival height at the distal proximal aspect of the prosthesis (CP-DE) was clinically measured. Radiographic images were obtained to measure the distance of the CP to the CB within the interimplant surfaces (CP-IP) and adjacent to the edentulous surfaces (CP-ED). The clinical measurement of CP-P for submerged and nonsubmerged implants was 3.57+/-1.17 mm and 3.10+/-0.82 mm for group 1, 3.57+/-0.78 mm and 3.16+/- 0.87 mm for group 2, and 3.35+/- 0.55 mm and 3.07+/-0.93 mm for group 3. The CP-DE was 3.25+/-0.77 mm for submerged and 2.78+/- 0.64 mm for nonsubmerged implants. The CP-IP for the submerged and nonsubmerged implants was 6.91+/-0.95 mm and 7.68+/-2.73 mm for group 1, 7.46+/-1.43 mm and 5.87+/-1.71 mm for group 2, and 7.72+/-0.81 mm and 7.59+/-1.33 mm for group 3. The CP-ED was 6.77+/-1.33 mm for submerged implants and 6.03+/-1.58 mm for nonsubmerged implants. There were no statistical significant differences for any of the measured parameters. We conclude that when the distance from the CP to the CB was 5 mm, interimplant distances of 1 to 3 mm did not affect papilla formation or crestal resorption of submerged or nonsubmerged implants in the dog model.

Bone morphogenetic proteins and noggin: Inhibiting and inducing fungiform taste papilla development

Fungiform papillae are epithelial specializations that develop in a linear pattern on the anterior mammalian tongue and differentiate to eventually contain taste buds. Little is known about morphogenetic and pattern regulation of these crucial taste organs. We used embryonic rat tongue, organ cultures to test roles for bone morphogenetic proteins, BMP2, 4 and 7, and antagonists noggin and follistatin, in development of papillae from a stage before morphological initiation (E13) or from a stage after the pre-papilla placodes have formed (E14). BMPs and noggin proteins become progressively restricted to papilla locations during tongue development. In E13 cultures, exogenous BMPs or noggin induce increased numbers of fungiform papillae, in a concentration-dependent manner, compared to standard tongue cultures; BMPs, but not noggin, lead to a decreased tongue size at this stage. In E14 cultures, however, exogenous BMP2, 4 or 7 each inhibits papilla formation so that there is a decrease in papilla number. Noggin substantially increases number of papillae in E14 cultures. Using beads for a highly localized protein delivery, papillae are inhibited in the surround of BMP-soaked beads and induced in large clusters around noggin-soaked beads. Follistatin, presented in culture medium or by bead, does not alter papilla formation or number. In all fungiform papillae that form under various culture conditions, the molecular marker, sonic hedgehog, is within each papilla. However, the BMP inhibitory effect on papillae is not prevented by disrupting sonic hedgehog signaling through addition of cyclopamine to cultures. BMPs and noggin alter cell proliferation in tongue epithelium in opposite ways, demonstrated with Ki67 immunostaining. We propose that the BMPs and noggin, colocalized within papilla placodes and the fungiform papillae per se, have opposing inhibitory and activating or inducing roles in papilla development in linear patterns. We present a model for these effects.

EGF and BMP inhibition of fungiform papilla formation in embryonic tongue

EGF and BMP inhibition of fungiform papilla formation in embryonic tongue

Genetic Analysis of Host Species Specificity of Magnaporthe oryzae Isolates from Rice and Wheat

ABSTRACT A Triticum isolate (pathogenic on wheat) of Magnaporthe oryzae was crossed with an Oryza isolate (pathogenic on rice) to elucidate mechanisms of their parasitic specificity on wheat. When the pathogenicity of their F (1) cultures (hybrids between a Triticum isolate and an Oryza isolate) was tested on wheat, avirulent and virulent cultures segregated in a 7:1 ratio. This result suggests that three loci are involved in avirulence of the Oryza isolate on wheat. One of the three loci conditioned papilla formation, whereas the others conditioned the hypersensitive reaction. Allelism tests revealed that the locus conditioning papilla formation is Pwt2 while one of the two loci conditioning the hypersensitive reaction is Pwt1. The other locus conditioning the hypersensitive reaction was different from any other known loci and, therefore, was designated as Pwt5.

Association of Shh and Ptc with keratin localization in the initiation of the formation of circumvallate papilla and von Ebner’s gland

The development of gustatory papillae in mammalian embryos requires the coordination of a series of morphological events, such as proliferation, differentiation and innervation. In mice, the circumvallate papilla (CVP) is a specialized structure that develops in a characteristic spatial and temporal pattern in the posterior region of the tongue dorsal surface. The distinct expression patterns of Shh and Ptc, which play important roles in the development of other epithelial appendages, have been localized in the trench wall that gives rise to von Ebner's gland (VEG). To define the cellular mechanisms responsible for morphogenesis and differentiation during early development of CVP and VEG, the localization patterns of keratins (cytokeratins) K7, K8, K18, K19, K14 and connexin-43, which are dependent on Shh expression in other developmental systems, have been examined in detail. The distinct localization of keratins K7, K8, K18, K19, K14 and connexin-43 in the epithelium giving rise to the CVP and VEG suggests that cytodifferentiation is established prior to morphological changes. Interestingly, the localization of proliferating cell nuclear antigen, a marker for cell proliferation, is similar to that of Shh. An understanding of the regulatory roles of cell-cell interactions and signalling molecules in orchestrating a mutual network will bring us nearer to defining the molecular and cellular mechanisms underlying morphogenesis in mammalian taste bud development.

Nonhost Resistance in Arabidopsis-Colletotrichum Interactions Acts at the Cell Periphery and Requires Actin Filament Function

Pathogenesis of nonadapted fungal pathogens is often terminated coincident with their attempted penetration into epidermal cells of nonhost plants. The genus Colletotrichum represents an economically important group of fungal plant pathogens that are amenable to molecular genetic analysis. Here, we investigated interactions between Arabidopsis and Colletotrichum to gain insights in plant and pathogen processes activating nonhost resistance responses. Three tested nonadapted Colletotrichum species differentiated melanized appressoria on Arabidopsis leaves but failed to form intracellular hyphae. Plant cells responded to Colletotrichum invasion attempts by the formation of PMR4/GSL5-dependent papillary callose. Appressorium differentiation and melanization were insufficient to trigger this localized plant cell response, but analysis of nonpathogenic C. lagenarium mutants implicates penetration-peg formation as the inductive cue. We show that Arabidopsis PEN1 syntaxin controls timely accumulation of papillary callose but is functionally dispensable for effective preinvasion (penetration) resistance in nonhost interactions. Consistent with this observation, green fluorescent protein-tagged PEN1 did not accumulate at sites of attempted penetration by either adapted or nonadapted Colletotrichum species, in contrast to the pronounced focal accumulations of PEN1 associated with entry of powdery mildews. We observed extensive reorganization of actin microfilaments leading to polar orientation of large actin bundles towards appressorial contact sites in interactions with the nonadapted Colletotrichum species. Pharmacological inhibition of actin filament function indicates a functional contribution of the actin cytoskeleton for both preinvasion resistance and papillary callose formation. Interestingly, the incidence of papilla formation at entry sites was greatly reduced in interactions with C. higginsianum isolates, indicating that this adapted pathogen may suppress preinvasion resistance at the cell periphery.

Scalloped Dental Implants: A Retrospective Analysis of Radiographic and Clinical Outcomes of 17 NobelPerfectTM Implants in 6 Patients

The scalloped dental implant (NobelPerfect, Nobel Biocare, Yorba Linda, CA, USA) is designed to biologically guide and facilitate interproximal bone remodeling during healing and to maintain bone height and papillae during functional loading. The design features of the scalloped implant include hard and soft tissue apposition areas, which are parallel to each other and mirror the cementoenamel junction. The hard tissue surface area is intended for osseointegration. The soft tissue surface area is meant to support the connective tissue zone and to provide a space for the subgingival margin of the restoration. Current literature on the clinical performance of the scalloped dental implant is limited. The aim of this study was to evaluate whether the scalloped dental implant maintains interproximal bone and the overlying soft tissue. Radiographs for six patients (mean age 40.5 years) treated with 17 implants (NobelPerfect) were reviewed for an 18-month follow-up evaluation of bone response. Orthodontic movement and/or autogenous bone augmentation had been provided to obtain the best possible soft and hard tissue dimensions prior to implant placement. A surgical guide was used for an optimal implant placement. No surgical flap was reflected, and implants were placed a minimum of 2 mm and a maximum of 3 mm apical (midbuccally) to the most apical portion of the surgical guide. Final optimal rotational alignment was achieved in all cases by not exceeding 45 Ncm. Implants were immediately restored with provisional crowns. Photographic documentation provided the basis for analysis of papillary response. Radiographic change in the interproximal bone level was obtained by computer analysis (ImageJ for Windows, National Institutes of Health, Bethesda, MD) by measuring the distance from the interproximal shoulder of the scalloped implant to the crest of the bone. When the scalloped implants were placed adjacent to existing natural dentition, the average bone level at placement and at 6, 12, and 18 months was -1.7, -3.5, -3.8, and -3.9 mm, respectively, compared with -1.0, -3.6, -4.3, and -4.4 mm respectively, when placed adjacent to other scalloped implants. Papillae formation exhibited no differences from the configuration that typically results after placement of conventional dental implants. Moreover, bone loss around the scalloped implants was notably greater than that expected after traditional implant placement. This chart review of 17 scalloped implants, followed for 18 months, determined that the scalloped implant design resulted in bone loss that was more severe than that associated with properly placed conventional dental implants. Further, the design showed no evidence of exceptional capacity to increase or maintain soft tissue height.

Inhibitory autocrine factors produced by the mesenchyme-derived hair follicle dermal papilla may be a key to male pattern baldness

Androgenetic alopecia, or male pattern baldness, is a common, progressive disorder where large, terminal scalp hairs are gradually replaced by smaller hairs in precise patterns until only tiny vellus hairs remain. This balding can cause a marked reduction in the quality of life. Although these changes are driven by androgens, most molecular mechanisms are unknown, limiting available treatments. The mesenchyme-derived dermal papilla at the base of the mainly epithelial hair follicle controls the type of hair produced and is probably the site through which androgens act on follicle cells by altering the regulatory paracrine factors produced by dermal papilla cells. During changes in hair size the relationship between the hair and dermal papilla size remains constant, with alterations in both dermal papilla volume and cell number. This suggests that alterations within the dermal papilla itself play a key role in altering hair size in response to androgens. Cultured dermal papilla cells offer a useful model system to investigate this as they promote new hair growth in vivo, retain characteristics in vitro which reflect their parent follicle's response to androgens in vivo and secrete mitogenic factors for dermal papilla cells and keratinocytes. To investigate whether cultured dermal papilla cells from balding follicles secrete altered amounts/types of mitogenic factors for dermal papilla cells than those from larger, normal follicles. We also aimed to determine whether rodent cells would recognize mitogenic signals from human cells in vitro and whether factors produced by balding dermal papilla cells could alter the start of a new mouse hair cycle in vivo. Dermal papilla cells were cultured from normal, balding and almost clinically normal areas of balding scalps and their ability to produce mitogenic factors compared using both human and rat whisker dermal papilla cells as in vitro targets and mouse hair growth in vivo. Normal scalp cells produced soluble factors which stimulated the growth of both human scalp and rat whisker dermal papilla cells in vitro, demonstrating dose-responsive mitogenic capability across species. Although balding cells stimulated some growth, this was much reduced and they also secreted inhibitory factor(s). Balding cell media also delayed new hair growth when injected into mice. Human balding dermal papilla cells secrete inhibitory factors which affect the growth of both human and rodent dermal papilla cells and factors which delay the onset of anagen in mice in vivo. These inhibitory factor(s) probably cause the formation of smaller dermal papillae and smaller hairs in male pattern baldness. Identification of such factor(s) could lead to novel therapeutic approaches.

Genetic instability of whiG gene during the aerial mycelium development of Streptomyces ambofaciens ATCC23877 under different conditions of nitrogen limitations

In Streptomyces ambofaciens, white papillae that genetic instability events generate during aerial mycelium growth, give rise to Pig-pap mutants which are unable to sporulate and devoid of large genome rearrangement. Knowing that genetic and environmental factors can influence the number of papillae per colony, we investigated the effect of nutrient limitated conditions of growth on the formation of white papillae. We observed that under nitrogen limitation and, most particularly, under amino acid limitation, the number of papillae per colony dramatically increased. Most of the Pig-pap mutants deriving from such papillae displayed a mutation in the whiG gene, which encodes the sigma factor σ whiG which is absolutely required for the sporulation process. In most cases, the mutation led to a loss of function. We showed that the Pig-pap mutants deriving from papillae appearing under usual growth conditions also frequently displayed null mutation of whiG too. As the whiG mutation ratio among the Pig-pap mutants isolated with or without nitrogen limited conditions did not change, the results described in this paper suggest that the production of papillae could constitute a response of S. ambofaciens to an amino acid limitation.