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1.
Dent J (Basel) ; 12(2)2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38392235

RESUMO

Psoriatic arthritis is defined as chronic inflammatory arthritis associated with psoriasis. The current data regarding gender differences in clinical manifestation and therapeutic outcomes of psoriatic arthritis are limited. Generally, men show a peripheral disease manifestation, while women have an axial distribution of the lesions. If we look at temporomandibular joint (TMJ) involvement, epidemiological data on the involvement of the TMJ are hard to find. Few studies on therapeutic management and the related impact on the quality of life are reported in the literature. Given the morpho-functional peculiarities of the TMJ and the different pain burdens between male and female genders, when manifestation of psoriatic arthritis occurs, clinicians should face it using a multidisciplinary approach for a correct diagnosis and successful treatment. This review aims to examine the diagnostic signs of psoriatic arthritis in the TMJ, the eventual variations of this disease in male and female patients, and the therapeutical strategies. The coordination of different specialties is fundamental to the remission of clinical symptoms and lesion regression.

2.
Hematol Rep ; 16(1): 22-31, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38247993

RESUMO

Plasmacytoma is a neoplastic disorder originating from plasma cells, with bone and soft tissue being common sites of manifestation. This report presents the clinical and radiological findings of a 65-year-old female patient who presented with an exophytic lesion in the upper right lateral incisor region. The lesion appeared as a unilocular radiotransparent area in imaging tests. Following an excisional biopsy, histological and immunohistochemical evaluations confirmed the presence of mature plasmacellular elements and small infiltrates of B and T lymphocytes. The patient did not exhibit systemic manifestations of multiple myeloma. Surgical intervention, in the form of enucleation of the lesion combined with root canal treatment and apicoectomy, was performed. This case underscores the rare occurrence of plasmacytoma in the jaw region and highlights the importance of surgical management in cases where structural damage or functional impairment is present. Further research on novel treatment approaches is also mentioned, including targeted therapies, immunomodulatory agents, and monoclonal antibodies. The patient is currently under the care of a hematologist for further investigation and the choice of the most appropriate therapy.

3.
Future Microbiol ; 19: 241-254, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38294280

RESUMO

Oral biofilm is the main cause of pathologies affecting the hard and soft oral tissues around teeth. Its main components are the periodontal pathogens and other bacteria of the supragingival and subgingival biofilm. Different alternative strategies that could be adjuvants to the usual periodontal treatments used to eliminate biofilms are available. One of these methods is antimicrobial photodynamic therapy using VIS and water-filtered infrared-A combined with a photosensitizer. In this review, different recent studies were collected to evaluate the antimicrobial effects of antimicrobial photodynamic therapy and the effectiveness of different types of photosensitizers.


This review summarizes different types of photodynamic therapy, a type of treatment that uses light to kill cells, which can be used to decontaminate the mouth and teeth. There are many bacteria in our mouths and on the surface of our teeth that can cause infections, such as dental caries, periodontitis and peri-implantitis. This review also looks at how effective these treatments are and suggests the use of clinical trials to confirm our findings.


Assuntos
Anti-Infecciosos , Fotoquimioterapia , Água/farmacologia , Anti-Infecciosos/farmacologia , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Biofilmes
4.
Neurobiol Dis ; 185: 106258, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37573956

RESUMO

The progressive myoclonic epilepsies (PMEs) are a group of rare neurodegenerative diseases characterized by myoclonus, epileptic seizures, and progressive neurological deterioration with cerebellar involvement. They include storage diseases like Gaucher disease, Lafora disease, and forms of neuronal ceroid lipofuscinosis (NCL). To date, 13 NCLs have been reported (CLN1-CLN8, CLN10-CLN14), associated with mutations in different genes. These forms, which affect both children and adults, are characterized by seizures, cognitive and motor impairments, and in most cases visual loss. In NCLs, as in other PMEs, central nervous system (CNS) neurodegeneration is widespread and involves different subpopulations of neurons. One of the most affected regions is the cerebellar cortex, where motor and non-motor information is processed and transmitted to deep cerebellar nuclei through the axons of Purkinje cells (PCs). PCs, being GABAergic, have an inhibitory effect on their target neurons, and provide the only inhibitory output of the cerebellum. Degeneration of PCs has been linked to motor impairments and epileptic seizures. Seizures occur when some insult upsets the normal balance in the CNS between excitatory and inhibitory impulses, causing hyperexcitability. Here we review the role of PCs in epilepsy onset and progression following their PME-related loss. In particular, we focus on the involvement of PCs in seizure phenotype in NCLs, highlighting findings from case reports and studies of animal models in which epilepsy can be linked to PC loss.


Assuntos
Epilepsia , Epilepsias Mioclônicas Progressivas , Lipofuscinoses Ceroides Neuronais , Animais , Lipofuscinoses Ceroides Neuronais/genética , Células de Purkinje , Epilepsias Mioclônicas Progressivas/genética , Convulsões
5.
Cell Biosci ; 13(1): 121, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37393328

RESUMO

BRAFV600E comes as two main splicing variants. The well-studied ref isoform and the recently discovered X1 isoform are co-expressed in cancer cells and differ in terms of 3'UTR length and sequence, as well as C-term protein sequence. Here, we use a melanoma model in zebrafish to study the role played by each isoform in larval pigmentation, nevi formation, and their progression into melanoma tumours. We show that both BRAFV600E-ref and BRAFV600E-X1 proteins promote larval pigmentation and nevi formation, while melanoma-free survival curves performed in adult fish indicate that BRAFV600E-ref protein is a much stronger melanoma driver that BRAFV600E-X1 protein. Crucially, we also show that the presence of the 3'UTR suppresses the effect of ref protein. Our data highlight the necessity to undertake a systematic study of BRAFV600E isoforms, in order to uncover the full spectrum of their kinase-(in)dependent and coding-(in)dependent functions, hence to develop more informed strategies for therapeutic targeting.

6.
J Stomatol Oral Maxillofac Surg ; : 101499, 2023 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-37178872

RESUMO

INTRODUCTION: Although the related risk of vascular necrosis due to filler injection is low, the outcomes can be severe when they occur. This systematic review aims to report the occurrence and treatment of vascular necrosis due to filler injection. MATERIALS AND METHODS: The systematic review was performed according to PRISMA guidelines. RESULTS: The results showed the most used treatment is a combination of pharmacologic therapy and hyaluronidase application, which is efficacy when applied in the first 4 h. In addition, even though management recommendations are available in literature, proper guidelines are unavailable due to the low number of complications occurrence. CONCLUSION: Clinical and high-quality studies on treatment and management of filler injection combination are necessary to provide scientific evidence on what to do in case of vascular complication occurrence.

7.
Curr Issues Mol Biol ; 45(4): 2984-2999, 2023 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-37185720

RESUMO

This study aimed to treat dental injuries by utilizing one of the most advanced tissue engineering techniques. In this study, an in vitro model was employed to investigate the proliferation and odontogenic differentiation of canine endometrial stem cells (C-EnSCs). Furthermore, the dentin regeneration potential of odontoblast like-cells (OD) derived from C-EnSCs was assessed in rats. The C-EnSCs were isolated by the enzymatic method and identified by flow cytometry. The C-EnSCs were encapsulated in fibrin gel associated with signaling factors to create the proper conditions for cell growth and differentiation. Then, the OD cells were associated with bone morphologic protein-2 (BMP-2) to promote dentin formation in vivo. The animal model used to evaluate the regenerative effect of cells and biomaterials included the preparation of the left maxillary first molar of rats for direct pulp capping operation. Animals were divided into four groups: group 1, a control group without any treatment, group 2, which received fibrin, group 3, which received fibrin with ODs (fibrin/ODs), and group 4, which received fibrin with ODs and BMP-2 (fibrin/ODs/BMP-2). The morphological observations showed the differentiation of C-EnSCs into adipose, bone, neural cells, and ODs. Furthermore, the histomorphometric data of the treated teeth showed how fibrin gel and BMP2 at a concentration of 100 ng/mL provided an optimal microenvironment for regenerating dentin tissue in rats, which was increased significantly with the presence of OD cells within eight weeks. Our study showed that using OD cells derived from C-EnSCs encapsulated in fibrin gel associated with BMP2 can potentially be an appropriate candidate for direct pulp-capping and dentin regeneration.

8.
Healthcare (Basel) ; 11(6)2023 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-36981485

RESUMO

Recently, the issue of the gender gap in dentistry and in the leadership in the dental field has placed new challenges on dental profession representatives and politicians. Indeed, the inequity between genders in healthcare workforces represents a limit to the progression of those in the professions, inhibiting talented colleagues from accessing high positions in the academic world and not providing adequate role models to inspire future generations. The Italian population practicing dentistry in 2021 was composed of 74% males and 26% females. The aim of this study is to analyze the level of the gender gap in the dental field in Italy by focusing on the gender distribution of professional leaders in institutional category associations and invited speakers at dental conferences accredited for the Continue Education in Medicine program. The search strategy considered three different fields in the national dentistry scene: the dental committee boards, the union category associations, and the cultural field. The roles in the dental boards were retrieved from the website of the National Medical and Dental Committee from 2018 to 2022; the roles in the union category associations at the provincial, regional, and national levels were retrieved from the related web pages, considering the period from 2018 to 2021; and the information about the speakers at national conferences from 1 January 2019 to 31 December 2021 was retrieved from the National Agency for Regional Health Services (Agenzia nazionale per i servizi sanitari regionali (AGENAS)) websites. The extracted data were grouped and examined using descriptive statistics (frequency), and due to the categorical nature of the data, non-parametric tests (chi-square tests) were used to assess any differences between the two genders. The null hypothesis was that there were no statistical differences between the two genders' distributions. A p-value was considered significant when <0.05. In addition, aiming to understand the representation of male and female dentists, a comparison of the distributions of males and females in the dental boards with the percentages of female and male dentists operating in Italy in 2021 was performed using a binomial test. The analysis of the data regarding the composition of the dental boards and of the union category association boards revealed a statistically significant difference in the distribution of the roles between the two genders at the regional and local levels, with a p-value of <0.05, and a significantly low representation of the women practicing dentistry (p < 0.05). In Italy, women practicing dentistry are underrepresented in dental organizations and in cultural events, given the low numbers of female dentists in leadership and/or speaker roles in the years 2018-2021. Even though the glass ceiling effect continues to affect Italian female dentists, initiatives and political measures have been taken to improve this condition and reach gender equity.

9.
Materials (Basel) ; 15(23)2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36499781

RESUMO

Over the past decade regenerative branches of dentistry have taken on more and more importance, resulting in the development of performing scaffold materials. These should induce cell adhesion, support, and guide the tissues' growth. Among the developed materials, we can include resorbable or non-membranes. The purpose of this study was to investigate the proliferation abilities and the attachment of human periodontal ligament fibroblasts (HPLIFs) over two bovine pericardium membranes with different thicknesses, 0.2 mm and 0.4 mm, respectively. These membranes have been decellularized by the manufacturer, preserving the three-dimensional collagen's structure. The HPLFs were cultured in standard conditions and exposed to the tested materials. XTT was performed to assess cell proliferation, while light microscopy (LM) and scanning electron microscopy (SEM) observations assessed fibroblast morphology at different times (T1, T2, and T3). Proliferation assays have shown a statistically significant difference in growth at T1 (p < 0.05) in the cells cultured with a thicker membrane compared to the thinner one. LM analysis showed healthy fibroblasts in contact with the membranes, appearing larger and with a polygonal shape. SEM observation demonstrated thickening of the fibroblasts which continued to adhere to the membrane's surface, with enlarged polygonal shape and developed filipodia and lamellipodia. These results showed a similar cell behavior over the two bovine pericardium membranes, demonstrating a cellular migration along and within the layers of the membrane, binding with membrane fibers by means of filopodial extensions. Knowledge of the effects of the collagen membranes derived from bovine pericardium on cellular behavior will help clinicians choose the type of scaffolds according to the required clinical situation.

10.
Pathogens ; 11(8)2022 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-36014988

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health concern responsible for the ongoing pandemic. Histopathological pieces of evidence on COVID-19 are not fully investigated. This review aims to provide, through microscopy investigations, a histopathological overview of COVID-19 structural and ultrastructural alterations in different organs and tissues, excluding the respiratory system. The authors systematically reviewed the literature over the period February 2020-July 2022. Selected databases were PubMed, Scopus, and Google Scholar. The search strategy included the following terms: "COVID-19" or SARS-CoV-2 and "histopathology" or "pathology"; and "microscopy" and "liver", "myocardium"," spleen", "testis", and "placenta". Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Thirty-one articles included in this systematic review demonstrated, at a histopathological level, that COVID-19 exerts detrimental effects on tissues, often promoting degenerative processes. Even if COVID-19 shows a histopathological tropism for the respiratory system, other tissues, from cardiovascular to reproductive, are affected by COVID-19. Therefore, this paper provides an up-to-date view of histopathological observations of the structural and ultrastructural alterations associated with COVID-19 and may contribute to a better knowledge of the physiopathological bases of this disease.

11.
Diagnostics (Basel) ; 12(8)2022 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-36010235

RESUMO

The purpose of this observational study is to evaluate the prevalence and main characteristics of bifid canals within a European adult population, analyzing cone-beam-computed tomography (CBCT). The population study examined 300 subjects. The CBCTs were performed between 2012 and 2019, using PaX-Zenith3D with a standard protocol of acquisition. The parameters analyzed were the presence and lengths of the bifid mandibular canals. The sample included 49% male and 51% female participants. The mean age of the patients was 47.07 ± 17.7 years. Anatomical variants of the mandibular canal were identified in 28.8% of the sides and 50.3% of the patients. In 7.3% of the subjects, the anatomical variants were present bilaterally. The most frequently encountered bifid canal was Type 3 (40.5%), followed by the Type 1 canal (39.3%), the Type 2 canal (14.5%), and the Type 4 canal (5.9%), 40% on the right side and 60% on the left side. The average length of the bifid canals located on the right side of the mandible was 11.96 ± 5.57 mm, compared to 11.38 ± 4.89 mm for those measured on the left side. The bifid mandibular canal is a common anatomical variation of the mandibular canal. It is fundamental to performing an accurate preoperative evaluation using CBCT analysis to avoid and/or reduce intraoperative and postoperative complications.

12.
Int J Mol Sci ; 23(9)2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35563664

RESUMO

Several types of deproteinised bovine bone mineral (DBBM) are available on the market, and each one is obtained with a thermic and chemical process that can differ, achieving different results. Currently, several protocols using low temperature are suggested to reduce the possible particle crystallisation during the production process. This study aimed to evaluate the biomorphological reaction of periodontal fibroblast cultures in contact with different DBBM particles treated with a low-temperature protocol (Thermagen®) and without exposure to sodium hydroxide (NaOH). Morphological evaluation was performed using light, confocal laser, and scanning electron microscopy, and the biological reaction in terms of proliferation was performed using an XTT proliferation assay at 24 h (T1), 72 h (T2), and 7 days (T3). The morphological analysis highlighted how the presence of the materials stimulated a change in the morphology of the cells into a polygonal shape, surface reactions with the thickening of the membrane, and expression of actin. In particular, the morphological changes were appreciable from T1, with a progressive increase in the considered morphological characteristics at T2 and T3 follow-ups. The proliferation assay showed a statistical significance between the different experimental materials and the negative control in T2 and T3 follow-ups. The post hoc analysis did not reveal any differences between the materials. In conclusion, the grafts obtained with the low-temperature extractions protocol and not exposed to NaOH solution showed positive morphological reactions with no differences in the sizes of particles.


Assuntos
Fibroblastos , Ligamento Periodontal , Animais , Bovinos , Células Cultivadas , Fibroblastos/metabolismo , Humanos , Minerais/metabolismo , Hidróxido de Sódio , Temperatura
13.
Clin Anat ; 35(6): 711-722, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35368109

RESUMO

The history of dentistry and medicine has a deep and ancient bond with the history of anatomy. From the ancient times to the present, the study of the human body represents the basis for research and clinical therapy. The historical contribution of anatomists to the development of dental medicine also helped in its characterization as an integrated but special and independent branch of medicine. From Galen's studies on animals to the discoveries of dental hard tissues characteristics using a microscope, this paper provides a brief literature review of how anatomy broadly contributed to the development of the dental sciences and how it still allows us to direct critical and fundamental anatomical-clinical paths for modern patient care. The history of the anatomy of teeth, description of skull bones, maxillary sinus characterization, the salivary glands, the tongue and labial musculature, and the microscopic anatomy of dental hard tissues will be examined. Historical research on the understanding of and progress in the oral field is of utmost importance in current clinical practice, thus inducing a future orientation in research. Most of the research especially that connected to the more distant historical periods has seen as main characters great personalities of morphological sciences, which contributes constituted fundamental basis for dental clinical aspects. Through a punctual and continuous historical assay, the ancient insights are reconnected to more recent knowledge and distinct research, thus permitting a detailed reconstruction of the historical-anatomical course in the progress of knowledge regarding the oral cavity and related anatomical structures.


Assuntos
Anatomistas , Anatomia , Dente , Animais , Odontologia , História Antiga , Humanos , Boca , Crânio
14.
Biomedicines ; 10(2)2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-35203428

RESUMO

Platelets are a cellular subgroup of elements circulating in the bloodstream, responsible for the innate immunity and repairing processes. The diseases affecting this cellular population, depending on the degree, can vary from mild to severe conditions, which have to be taken into consideration in cases of minor dental procedures. Their secretion of growth factors made them useful in the regenerative intervention. The aim of this review is to examine the platelets from biological, examining the biogenesis of the platelets and the biological role in the inflammatory and reparative processes and clinical point of view, through the platelets' pathology and their use as platelets concentrates in dental regenerative surgery.

15.
J Theor Biol ; 535: 110980, 2022 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-34915043

RESUMO

We here propose a one-dimensional spatially explicit phenotype-structured model to analyze selected aspects of avascular tumor progression. In particular, our approach distinguishes viable and necrotic cell fractions. The metabolically active part of the disease is, in turn, differentiated according to a continuous trait, that identifies cell variants with different degrees of motility and proliferation potential. A parabolic partial differential equation (PDE) then governs the spatio-temporal evolution of the phenotypic distribution of active cells within the host tissue. In this respect, active tumor agents are allowed to duplicate, move upon haptotactic and pressure stimuli, and eventually undergo necrosis. The mutual influence between the emerging malignancy and its environment (in terms of molecular landscape) is implemented by coupling the evolution law of the viable tumor mass with a parabolic PDE for oxygen kinetics and a differential equation that accounts for local consumption of extracellular matrix (ECM) elements. The resulting numerical realizations reproduce tumor growth and invasion in a number scenarios that differ for cell properties (i.e., individual migratory behavior, duplication, and mutation potential) and environmental conditions (i.e., level of tissue oxygenation and homogeneity in the initial matrix profile). In particular, our simulations show that, in all cases, more mobile cell variants occupy the front edge of the tumor, whereas more proliferative clones are selected at more internal regions. A necrotic core constantly occupies the bulk of the mass due to nutrient deprivation. This work may eventually suggest some biomedical strategies to partially reduce tumor aggressiveness, i.e., to enhance necrosis of malignant tissue and to promote the presence of more proliferative cell phenotypes over more invasive ones.


Assuntos
Neoplasias , Matriz Extracelular/patologia , Humanos , Cinética , Mutação , Neoplasias/patologia , Fenótipo
17.
Int J Mol Sci ; 22(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34445386

RESUMO

Understanding the biological and morphological reactions of human cells towards different dentinal derivate grafting materials is fundamental for choosing the type of dentin for specific clinical situations. This study aimed to evaluate human periodontal ligament fibroblasts (hPLF) cells exposed to different dentinal derivates particles. The study design included the in vitro evaluation of mineralized dentine (SG), deproteinized and demineralized dentine (DDP), and demineralized dentine (TT) as test materials and of deproteinized bovine bone (BIOS) as the positive control material. The materials were kept with the hPLF cell line, and the evaluations were made after 24 h, 72 h, and 7 days of in vitro culture. The evaluated outcomes were proliferation by using XTT assays, the morphological characteristics by light microscopy (LM) and by the use of scanning electron microscopy (SEM), and adhesion by using confocal microscopy (CLSM). Overall, the experimental materials induced a positive response of the hPLFs in terms of proliferation and adhesion. The XTT assay showed the TT, and the SG induced significant growth compared to the negative control at 7 days follow-up. The morphological data supported the XTT assay: the LM observations showed the presence of densely packed cells with a modified shape; the SEM observations allowed the assessment of how fibroblasts exposed to DDP and TT presented cytoplasmatic extensions; and SG and BIOS also presented the thickening of the cellular membrane. The CLMS observations showed the expression of the proliferative marker, as well as and the expression of cytoskeletal elements involved in the adhesion process. In particular, the vinculin and integrin signals were stronger at 72 h, while the actin signal remained constantly expressed in all the follow-up of the sample exposed to SG material. The integrin signal was stronger at 72 h, and the vinculin and actin signals were stronger at 7 days follow-up in the sample exposed to DDP material. The vinculin and integrin signals were stronger at 72 h follow-up in the sample exposed to TT material; vinculin and integrin signals appear stronger at 24 h follow-up in the sample exposed to BIOS material. These data confirmed how dentinal derivates present satisfying biocompatibility and high conductivity and inductivity properties fundamental in the regenerative processes. Furthermore, the knowledge of the effects of the dentin's degree of mineralization on cellular behavior will help clinicians choose the type of dentine derivates material according to the required clinical situation.


Assuntos
Biomarcadores/metabolismo , Substitutos Ósseos/farmacologia , Dentina/química , Ligamento Periodontal/citologia , Animais , Substitutos Ósseos/química , Bovinos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Integrinas/metabolismo , Teste de Materiais , Microscopia Confocal , Microscopia Eletrônica de Varredura , Ligamento Periodontal/efeitos dos fármacos , Ligamento Periodontal/metabolismo , Vinculina/metabolismo
18.
Antibiotics (Basel) ; 10(7)2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34356795

RESUMO

Enterococcus faecalis is a microorganism that can be found in the oral cavity, especially in secondary endodontic infections, with a prevalence ranging from 24-70%. The increase in the ability to form biofilms in the presence of subinhibitory antibiotic concentrations is a phenomenon that is observed for a wide variety of bacterial pathogens and is associated with increased resistance. In this study, therefore, six E. faecalis isolates from an endodontic environment and two control strains were exposed to subinhibitory concentrations of Penicillin G, Amoxicillin, Doxycycline, Fosfomycin, Tetracycline and Vancomycin and examined for their biofilm formation abilities. The minimum inhibitory concentration (MIC) was determined for all E. faecalis isolates. A culture of the isolate was mixed with a serial dilution series of the respective antibiotic, incubated overnight and the biofilm formation was analyzed using a microtiter plate assay. All isolates were able to form biofilms in the absence of an antibiotic. A significant increase in biofilm formation of up to more than 50% was found in the isolates exposed to subinhibitory concentrations of various antibiotics. Most isolates showed a significant increase in Fosfomycin (7/8), Doxycycline (6/8) and Tetracycline (6/8). Three endodontic isolates showed a significant increase in five of the antibiotics examined at the same time. On exposure to Vancomycin, three endodontic isolates and the two control strains showed an increase. The increase in the ability to form biofilms extended over a concentration range from 1/2 to 1/64 of the MIC concentration. Antibiotics may reach certain niches in the oral cavity at subinhibitory concentrations only. This can increase the biofilm formation by enterococci, and in turn lead to decreased susceptibility of these taxa to antibiotics.

20.
Bull Math Biol ; 83(6): 69, 2021 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-33973064

RESUMO

Collective migration of cells and animals often relies on a specialised set of "leaders", whose role is to steer a population of naive followers towards some target. We formulate a continuous model to understand the dynamics and structure of such groups, splitting a population into separate follower and leader types with distinct orientation responses. We incorporate leader influence via three principal mechanisms: a bias in the orientation of leaders towards the destination (orientation-bias), a faster movement of leaders when moving towards the target (speed-bias), and leaders making themselves more clear to followers when moving towards the target (conspicuousness-bias). Analysis and numerical computation are used to assess the extent to which the swarm is successfully shepherded towards the target. We find that successful leadership can occur for each of these three mechanisms across a broad region of parameter space, with conspicuousness-bias emerging as the most robust. However, outside this parameter space we also find various forms of unsuccessful leadership. Forms of excessive influence can result in either swarm-splitting, where the leaders break free and followers are left rudderless, or a loss of swarm cohesion that leads to its eventual dispersal. Forms of low influence, on the other hand, can even generate swarms that move away from the target direction. Leadership must therefore be carefully managed to steer the swarm correctly.


Assuntos
Liderança , Conceitos Matemáticos , Animais
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