Periodontal ligament cells as alternative source for cell-based therapy of tendon injuries: in vivo study of full-size Achilles tendon defect in a rat model.

Tendon's natural healing potential is extremely low and inefficient, with significant dysfunction and disability due to hypocellularity and hypovascularity of tendon tissues. The application of stem cells can aid in significantly enhanced repair of tendon rupture; therefore, the main aim of this study is to assess the potential of using periodontal ligament cells (PDL), usually obtained from patients undergoing orthodontic treatment, as a novel cell source for cell-based therapy for tendon injuries in a clinically relevant rat full-size Achilles tendon defect. In addition, the study compares the differences between the healing effects of Achilles tendon-derived cells (AT) versus PDL and, hence, comprises of four experimental groups, native tendon (NT), empty defect (ED), PDL and human AT (hAT). The tendon healing in each group was assessed in the late remodelling phase at 16 weeks after surgery using a combination of methods, including evaluation of gross morphological appearance; various histological and immunohistological stainings; and detailed analyses of cell morphometry. Based on these outcome measures, PDL cell-implanted tendons exhibited not only advanced tissue maturation, less ectopic fibrocartilage formation, more organised collagen fibres, tendon matrix expression corresponding to the final healing stage, and better cell-morphometry parameters when compared with the ED group, but were also very similar to the tendons treated with hAT-derived cells. Taken together, our study clearly demonstrates the feasibility of using PDL cells as a novel cell source for tendon repair and strongly recommends this cell type for the future development of innovative regenerative applications for treatment of different tendon or ligament pathologies.

[Pseudocyst of the scalp: two cases]. / Pseudo-kystes du cuir chevelu : deux cas.

BACKGROUND: Pseudocysts of the scalp are a poorly known entity. Herein we present two new cases. CASE REPORT: Two male patients aged respectively 42 and 33 years had been presenting a small number of pseudocystic lesions on the scalp, as well as alopecia limited to the same region, for a number of years. Inflammatory episodes had occurred in certain lesions. In one case, biopsy showed an aspect typical of pseudocyst of the scalp and the lesions appeared to stabilize on treatment with doxycycline. DISCUSSION: Pseudocysts of the scalp are also known as aseptic nodules of the scalp, a term that appears to us to be less appropriate. They form lesions involving alopecia and they may be inflammatory to various degrees. Following incision of these lesions, a deep yellow fluid liquid is released that may be shown by microbiological analysis to be sterile. Histological analysis reveals a pseudocystic wall associated with perilesional inflammatory remodelling. The cysts are frequently confused with dissecting cellulitis of the scalp, but the prognosis is more encouraging. Treatment involves surgical excision, and intralesional injections of corticosteroids or doxycycline.

Comparison of tenocytes and mesenchymal stem cells seeded on biodegradable scaffolds in a full-size tendon defect model.

In order to investigate cell-based tendon regeneration, a tendon rupture was simulated by utilizing a critical full-size model in female rat achilles tendons. For bridging the defect, polyglycol acid (PGA) and collagen type I scaffolds were used and fixed with a frame suture to ensure postoperatively a functional continuity. Scaffolds were seeded with mesenchymal stem cells (MSC) or tenocytes derived from male animals, while control groups were left without cells. After a healing period of 16 weeks, biomechanical, PCR, histologic, and electron microscopic analyses of the regenerates were performed. Genomic PCR for male-specific gene was used to detect transplanted cells in the regenerates. After 16 weeks, central ossification and tendon-like tissue in the superficial tendon layers were observed in all study groups. Biomechanical test showed that samples loaded with tenocytes had significantly better failure strength/cross-section ratio (P < 0.01) compared to MSC and the control groups whereas maximum failure strength was similar in all groups. Thus, we concluded that the application of tenocytes improves the outcome in this model concerning the grade of ossification and the mechanical properties in comparison to the use of MSC or just scaffold materials.

Interfacial activity of phosphonated-PEG functionalized cerium oxide nanoparticles.

In a recent publication, we have highlighted the potential of phosphonic acid terminated PEG oligomers to functionalize strong UV absorption cerium oxide nanoparticles, which yield suspensions that are stable in aqueous or organic solvents and are redispersible in different solvents after freeze-drying. In the present work, we highlight the interfacial activity of the functional ceria nanoparticles and their potential to modify hydrophobic surfaces. We first investigated the phosphonated-PEG amphiphilic oligomers behavior as strong surface active species forming irreversibly adsorbed layers. We then show that the oligomers interfacial properties translate to the functional nanoparticles. In particular, the addition of a small fraction of phosphonated-PEG oligomers with an extra C16 aliphatic chain (stickers) into the formulation enabled the tuning of (i) the nanoparticles adsorption at the air/water, polystyrene/water, oil/water interfaces and (ii) the particle/particle interaction in aqueous solutions. We also found that dense and closely packed two-dimensional monolayers of nanoceria can be formed by spontaneous adsorption or surface compression using a Langmuir trough. A hexagonal organization controlled by reversible and repulsive interaction has been characterized by GISAXS. Mono- or multilayers can also be stably formed or transferred on solid surfaces. Our results are key features in the field of polymer surface modification, solid-stabilized emulsions (Pickering), or supracolloidal assemblies.

Self-assembly of charged amphiphilic diblock copolymers with insoluble blocks of decreasing hydrophobicity: from kinetically frozen colloids to macrosurfactants.

We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 °C and 1 M.

Chemical analysis and aqueous solution properties of charged amphiphilic block copolymers PBA-b-PAA synthesized by MADIX.

We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter chi(PBA/PAA), determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by liquid chromatography at the point of exclusion and adsorption transition, LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA-b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur.

Infundibula of equine maxillary cheek teeth: Part 2: Morphological variations and pathological changes.

Incomplete cemental filling of the infundibula of equine maxillary cheek teeth (CT) is a common feature. Depending on the extent of the defect, three stages of infundibular decay have been suggested. However, histomorphological criteria to identify non-pathological abnormalities and destructive changes have not been defined. Six hundred and eighty eight CT with no evidence of dental diseases and 55 diseased permanent, fully erupted maxillary CT were evaluated on a macroscopic level by assessing the occlusal surface and horizontal sections, including porphyrin assays to detect residual blood within the infundibular cementum. Selected specimens were investigated on a microscopic level using routine and immunohistological staining methods to identify possible routes for the spread of infectious agents from the infundibulum into the endodontic system. Infundibular cemental hypoplasia was defined as a non-pathological developmental abnormality and was detected in >50% of CT with no evidence of dental diseases and in >70% of diseased CT. The first molar (Triadan 09) showed the highest prevalence (75%) of infundibular cemental hypoplasia. The mesial infundibulum was more often affected than the distal infundibulum. Infundibular erosion was considered as the most appropriate term to describe destructive infundibular changes. Infundibular erosion was present in <6% of CT with no evidence of dental diseases, but was detected in >27% of diseased teeth, always accompanied by endodontic disease. This suggests that teeth affected by infundibular cemental hypoplasia are prone to destructive erosion, which possibly leads to endodontic disease. Morphological factors that supplement this ethological hypothesis were described. In 74% of infundibula residual blood was identified, although no vital blood vessels were detected. It is assumed that this content of blood remained in the ample infundibular cemental blood system after tooth eruption and creates a favorable environment for microbial growth. The infundibular enamel was characterised by numerous infoldings to variable degrees and depths. In certain areas focal enamel aplasia was observed. These morphological features might contribute to microbiological settlement and spread of infectious agents through the infundibular wall into the endodontic system.

Development of cellulose sulfate-based polyelectrolyte complex microcapsules for medical applications.

Microencapsulation, as a tool for immunoisolation for allogenic or xenogenic implants, is a rapidly growing field. However most of the approaches are based on alginate/polylysine capsules, despite this system's obvious disadvantages such as its pyrogenicity. Here we report a different encapsulation system based on sodium cellulose sulfate and polydiallyldimethyl ammonium chloride for the encapsulation of mammalian cells. We have characterized this system regarding capsule formation, strength and size of the capsules as well as viability of the cells after encapsulation. In addition, we demonstrate the efficacy of these capsules as a "microfactory" in vitro and in vivo. Using encapsulated hybridoma cells we were able to demonstrate long-term release of antibodies up to four months in vivo. In another application we could show the therapeutic relevance of encapsulated genetically modified cells as an in vivo activation center for cytostatic drugs during tumor therapy.

Development of a molecular diagnosis assay based on electrohybridization at plastic electrodes and subsequent PCR.

Technologies enabling specific recognition of medically relevant nucleic acid sequences will play a pivotal role in future medical diagnosis. Whereas many approaches to molecular diagnosis systems include DNA microarrays on chips and fluorometric detection, the basis of our approach is the use of inexpensive components like plastic or metal thin film electrodes with low multiplexing and an electrochemical detection unit. To increase the sensitivity, PCR can be used as an intermediate step. For selective enrichment, specific nucleic acid probes were covalently attached at their 5'-ends to conducting polycarbonate/carbon fiber electrodes. Complementary oligonucleotides were enriched at the electrodes by cyclic inversion of an electrochemical potential, transferred into a PCR vial and thermally or electrochemically desorbed. The analysis of the PCR product shows the efficiency and selectivity of the electrochemical enrichment. Hybridization of DNA was shown by electrochemical methods, in this work especially by differential pulse voltammetry (DPV) using the single strand specific hybridization redox indicator osmium(VIII)-tetroxide, and potentiometric stripping analysis (PSA). This combination of experimental methods is the basis for a molecular diagnosis system including a disposable nucleic acid modified working electrode for specific enrichment, detection and quantification, and an optional capillary PCR module for fast amplification.

Rapid method for the isolation of the mature collagen cross-links, hydroxylysylpyridinoline and lysylpyridinoline.

Hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) are two non-reducible cross-links of mature collagen which are formed by a sequence of post-translational modifications. HP is a derivative of three residues of hydroxylysine and is present in almost all mature tissues (e.g., tendons, vessel walls, cartilage, teeth and bone). LP is a derivative of two residues of hydroxylysine and one residue of lysine and is present only in dentine and bone. Neither cross-link is found in normal human skin. HP and LP were purified from commercially available bone gelatine ("ossein hydrolysate") by preparative reversed-phase HPLC and the degree of purity was verified by amino acid determination ( > 98% dry mass). Hydroxylysylpyridinoline and lysylpyridinoline are promising markers in urine of collagen resorption because their levels in urine should reflect only the breakdown of collagen fibres of skeletal tissues. The two components were used as external standards and the determination of HP and LP in urine provides a good means for the specific evaluation of pathological conditions associated with increased bone resorption, e.g., high turnover post-menopausal osteoporosis.

An improved assay for measuring the transverse redistribution of fluorescent phospholipids in plasma membranes.

The internalization of fluorescent 7-nitro-2,1,3-benzoxadiazol-4-yl (NBD)-phospholipids from the plasma membrane can be assessed by the irreversible quenching of analogues in the outer leaflet by dithionite. Here we have utilized this assay to follow the redistribution of short-chain C6-NBD-sphingomyelin and C6-NBD-phosphatidylserine from the cell membrane of human gingiva fibroblasts. The significant uptake of dithionite across the plasma membrane and the subsequent reduction of NBD-analogues exposed to the cytoplasmic lumen does not allow an accurate measurement of the amount of internalized lipid probes even at low temperature. We could show that a precise determination can be achieved by extraction of analogues remaining in the exoplasmic half by a short pretreatment with bovine serum albumin prior to addition of dithionite. The fluorescence of those analogues localized to the cytoplasmic lumen was slowly destroyed by permeating dithionite. The fluorescence of those NBD-probes which are localized in the inner layer of intracellular vesicles remained almost unaffected in the time course of the assay. Thus, this approach allows to distinguish between different routes of internalization of NBD-phospholipids from the plasma membrane.

[Ice hockey accidents]. / Accidenti da hockey su ghiaccio

The present study is based on 2680 ice hockey accidents encountered in Switzerland over a period of 5 years: 1880 injuries during matches are compared with 800 that took place in training. Age: the athletes injuried during training were younger that 20 in 40% of cases; 38% of injuries in matches occurred to players aged between 20 and 24. 25% of accidents were caused by blows from the stick, particularly as a result of "high sticking"; 5% by skates; 17% by the puck (hard rubber); 17% by collisions; the remainder by crashing against the barrier, falls on the ice, body checking, etc. The most frequent injuries (42%) involved head and face: 740 dental injuries about of the 1460 facial injuries and 160 cases of concussion. The injuries affected: the legs in 21% of cases; the feet in 11%; the arms in 11%; the hands in 7% and the trunk in 8%. The commonest types of injuries were crushings and bruisings; during matches, 13% of the 1880 lesions involved fractures, a quarter of which were the result of collisions. Preventive measures would require all players to wear a helmet to protect their head, face and mouth; protective barriers should be sufficiently high; the game and rules should be taught from school age on and fair play should be instilled.

[Extraction behavior of polypropylenes. 87. Problems in the use of plastic containers for fluid drugs]. / Extraktionsverhalten von Polypropylen. 87. Mitteilung: Zur Problematik des Einsatzes von Kunststoffbehältern für flüssige Arzneizubereitungen.

Studies on the extraction of antioxidants in different polypropylene samples subjected to variable extraction terms proved that storing neutral or faintly acid infusion solutions or those with an ethanol content up to 10% for several months, the extracted antioxidants are in allowable ranges. Insignificantly increased amounts of antioxidants are delivered to alkaline solutions and to ethanol/water mixtures having increased ethanol contents. The methods and specified limiting values of the GDR pharmacopoeia have been consulted for the semiquantitative estimate of extractives.

Using standardized patients to assess presentation of a dental treatment plan.

In this new era of relationship-based care, involvement in treatment planning and goal setting is a high priority for patient satisfaction. This study reports on the use of standardized patients (SPs) in training third-year dental students to gather dental, medical, and psychosocial information from patients and to involve the patient in the decision-making process leading to the dental treatment plan. Among the skill areas measured, students were most successful in gathering dental information, with 94 percent of the students obtaining the complete set. Students were least successful in identifying the patient's goals for treatment (81 percent of the students identified the patients' goals). Students were most challenged by discussing sensitive topics with patients such as grief-related depression (25 percent of the students recognized and discussed such topics). It is important that dental schools familiarize students with patient issues and teach them how to talk effectively to patients about personal issues and to incorporate those issues into a discussion of the treatment plan for the patient. Standardized patients can be used effectively toward this end.

Medium to long-term results with the cementless threaded Acetabular Munich II type cup.

Compared to pressfit cups, little information exists about the results of screwed cups in hip arthroplasty. 51 cementless or hybrid (cemented stem) primary total hip replacements with a cementless corundium blasted titaniumn alloy threaded Aesculap Munich II type cup were examined with a mean follow up of 7.9 years. 23 of the patients were male and 28 patients were female. From these cups 22 were implanted on the right side and 29 on the left. The results were compared to 53 patients (28 male, 25 female, 29 right side, 24 left side) with the threaded Aesculap Munich I type cup, that has a smooth surface and a direct contact of bone with the polyethylene inlay. The mean follow up ws 10.2 years. The early and medium to long-term clinical and radiographic results show an encouraging improvement of the Merle d'Aubigné Score of the type II cup compared to the type I cup. Two of the Aesculap type Munich II cups had to be revised; four showed radiologic signs of loosening. In conclusion, the threaded Aesculap cup type Munich II seems to be a decisive advance in the development of threaded acetabular hip cups. The intermediate results exceed those from smooth-surface screwed rings and compare favourably with those from cemented cups and with those from cementless press-fit metal-backed cups.

Anticipatory stress reduction among chronic pain patients.

Stress has long been viewed as a contributor to the pain experienced by chronic pain patients. The purpose of this research was to study the relationship between anticipated and experienced stress and anticipated and experienced pain levels among three patient groups: chronic pain patients, patients about to receive molar extraction (acute pain group), and a no-pain comparison group. Results showed that chronic pain patients anticipated significantly more stress than did an acute pain or a non-pain comparison patient group but reported non-significant differences in the actual level of stress experienced. A secondary purpose of this study was to examine cognitive factors, such as perceived daily hassles, which may contribute to this increased anticipatory stress. Results showed that there was consistency among the chronic pain patients as to the types of anticipated stressors, which were similar to those previously reported by chronic headache sufferers. The chronic pain group had significantly higher scores than the two remaining groups on the stress they anticipated from hassles related both to practical considerations (F2.45 = 3.5, p < 0.05) and to health (F2.45 = 9.37, p < 0.001). Strategies the dentist can use in combination with dental therapy to reduce cognitive-based anticipatory stress as well as strategies for collaboration with the patient and a mental health therapist are discussed.

[Cowden disease: treatment with acitretine]. / Maladie de Cowden: traitement par acitrétine.

INTRODUCTION: Cowden's disease is a rare hereditary skin disease which is important to recognize due to the risk of cancer. CASE REPORT: A 40-year-old man was hospitalized for psoriasis. He presented florid papillomatous lesions involving the lip and the buccal cavity, a thyroid adenoma and polyposis of the gut. The diagnosis of Cowden's disease was retained. Treatment with acitretin, 0.75 mg/kg/d was initiated for the psoriatic lesions. Hypertrophic lesions of the lip and mouth regressed during treatment but reappeared when the drug dose was tapered of then withdrawn. The course of the polyposis was not verified. DISCUSSION: This case demonstrates the frequency of digestive tract involvement in Cowden's disease and the favorable, though transient, effect of oral retinoids on mucosal lesions in Cowden's disease.

[Bristle anchoring and bristle end-rounding in adults' toothbrushes]. / Borstenverankerung und Borstenabrundung bei Erwachsenenzahnbürsten.

Scanning electron microscopic study of bristle heads of 8 toothbrush brands commercially available in the Federal Republic of Germany and Switzerland has shown qualitative variations in the rounding of bristle ends. The percentage of acceptable end rounding of the bristles was for 4 brands above 75% and for 2 brands 55-56%. For 2 products, the percentage was below 40%. The new method of welding bristle bundles at their base into the head of the toothbrush was used only by one producer.

In-vitro and in-vivo comparative analysis of four tissue pH monitoring systems.

The purpose of this investigation was to identify the type of pH-reference electrode combination that is the most suitable and reliable in clinical applications involving long-term postoperative monitoring of microvascular reconstructive transplants and diagnosis of compartment syndrome. Four types of pH-sensing devices were chosen for the study: a standard glass pH electrode, a polymer-based pH electrode, an ISFET pH sensor, and a fiberoptic pH sensor. Various combinations of electrodes were tested in vitro for typically four days. The glass and polymer electrodes maintained stable pH readings, averaging drifts of 0.14 +/- 0.07 and 0.14 +/- 0.08 pH units per 96 hours, respectively. The fiberoptic sensors displayed an average drift of 0.20 +/- 0.15 pH units per 96 hours. ISFET sensors displayed nearly linear drifts, averaging 1.36 +/- 0.54 pH units per 96 hours. When placed in healthy animal tissue, glass and polymer electrode pH readings followed the arterial blood pH values, measured by a blood gas analyzer. In compromised tissue, both glass and polymer electrodes recorded falling pH levels correctly, indicating ischemic conditions. Generally, ISFET sensors in healthy tissue produced pH readings that did not correlate well with arterial blood pH values. Fiberoptic sensors monitored healthy-tissue pH correctly; however, mechanical disturbances of the fiberoptic sensor and occasional discontinuation of computer operation would shift the pH output significantly (at times by 0.2 pH units), resulting in subsequent inaccurate pH readings. The glass electrode was the only sensor evaluated clinically. It correctly indicated tissue viability in all clinical cases, involving both healthy and ischemic tissue. The authors conclude that the glass pH electrode has the best combination of characteristics for clinical tissue pH measurements.

Contributors to dentists' job satisfaction and quality of life.

Every career has the potential for producing personal satisfaction and dissatisfaction, and much of that assessment is dependent on what an individual values in life. The purpose of this study was to identify factors that contribute to dentists' job satisfaction and the overall quality of their lives. Multiple regression analysis was performed to find the best set of predictor variables. After controlling for age, sex, and length of time in practice, the combination of variables that best predicted overall job satisfaction was income, respect, and patient relations (R2 = 57%). The combination of variables that best predicted overall quality of life, after again controlling for age, sex, and length of time in practice were income, professional time, and personal time (R2 = 83%). Although over half of the dentists surveyed are satisfied with their career, they are dissatisfied with their level of stress, professional environment (threat of malpractice litigation), and amount of personal time. Implications and recommendations are discussed.