Significant decrease of facial cellulitis admissions during COVID-19 lockdown in France: A multicentric comparative study.

During the 2020 coronavirus pandemic, a lockdown was imposed in France during the first wave. An apparent decrease in incidence of cellulitis of odontogenic origin was noticed then. This study aimed to compare the incidence of cellulitis during this extraordinary period with the same period in 2018 and 2019, based on retrospective multicentric data. All maxillofacial surgery departments in French public hospitals were contacted. Responders were asked to include all patients admitted for the surgical drainage of a head and neck abscess of odontogenic origin during the first 2020 lockdown period, and in a similar time frame in 2018 and 2019 (control group), based on screening the French diagnostic and therapeutic classification of medical acts. We report a 44% significant nationwide decrease in the incidence of admissions for cellulitis. There were 187 patients in 2020 for 334 and 333 patients in 2018/2019 respectively. The reasons to explain this finding are hypothetical (organizational reasons leading to earlier management, patients' fear to seek for medical management, usual excess in surgical indications or concomitant decrease of non-steroidal anti-inflammatory drugs delivery). Whatever the explanation, it would be of great interest to find it out in order to improve the prevention of cellulitis.

[An update on focal infection of oral origin]. / Point actuel sur l'infection focale d'origine buccodentaire.

Focal infection of oral origin means that an oral infectious focus may have widespread effects. This concept remains controversial since it is difficult to prove the oral origin of germs responsible for an extra-oral infection. Experiments on animal models and clinical studies suggested several physiopathological mechanisms: bacteremia, toxinic and immunological mechanisms. Various operations induce the passage of bacterial flora (transcytosis) and its toxins into the bloodstream: oral care, chewing, or tooth brushing. Bacteremia is worsened by poor oral hygiene or an infection. The germs are usually destroyed by the host's reticuloendothelial system in a few minutes, but the presence of a valvular disease or a weak immune system favors focal infection. Besides infectious endocarditis, this may concern cardiovascular diseases, lung infections, prematurity and hypotrophy, diabetes, prosthetic infections, cerebral abscesses, etc. This update is based on literature review, selected according to its high level of scientific proof, as well as on a selected choice of consensus conferences. The current recommendation is to limit antibiotic prophylaxis to the high bacteremia risk procedures and to patients highly at risk of developing a focal infection.

The significance of computer-assisted surgery in avoiding double-barrel fibula grafts in reconstruction of the horizontal mandibular ramus.

It is recognized that the mandibular reconstruction with free flap allows for both functional and aesthetic restoration. The flap must be used for reconstruction of a smooth lower mandibular contour and also the alveolar bone to allow dental rehabilitation. The double-barrel fibula free flap does respond well to these imperatives, but it increases risk of vascular complications. To overcome these risks, we propose a single-barrel fibula free flap, positioned at the alveolar level and a customized 3D implant, designed by computer-assisted surgery, at the basilar level. The interest of the single-barrel fibula associated with a customized 3D implant compared to the double-barrel fibula free flap is twofold: it decreases the vascular risks associated with the plication of the second pedicle and allows patients to have a pedicle of greater length. It also allows them to have a good cortical bone placed in the alveolar bone to rehabilitate the mastication function.

The role of telemedicine in the management of maxillofacial trauma in emergency departments - preliminary results.

New technologies have over the past forty years become widespread across all domains of basic and applied research particularly in health-related fields. Telemedicine is a form of remote medical practice using information and communication technologies. It connects one or more health professionals with other health professionals or with patients. Within the framework of emergencies in maxillofacial surgery, requests received for specialist advice often pertain to procedures to be followed for facial wounds, bites, burns, maxillofacial bone trauma or facial cellulitis. These requests for specialist advice were previously made by phone between emergency physicians and maxillofacial specialists, with exchange of patient photos by text messaging, which raised security issues. We collaborated with the Telehealth Normandy Health Cooperation Group (GCS TSBN) for the implementation of a mobile application using the "Therap-e" telemedicine platform. This platform links together websites and remote health professionals via the Internet. Physicians communicate over a mobile network or from a health institution, in online or offline mode, synchronously or asynchronously, using any medium (tablet, PC, Mac, smartphone). This scheme both ensures secure transmission of personal and clinical data (especially facial photographs) and records specialist advice in patient medical records. The purpose of tele-expertise applications in an emergency context is to provide a solution to the demographic problems facing healthcare professionals and to rise to the growing challenges surrounding quality and security issues.

Study of the mechanical reliability of an S-shaped adjustable osteosynthesis plate for bilateral sagittal split osteotomies. Study on 15 consecutive cases.

INTRODUCTION: The main challenge during the osteosynthesis of a bilateral sagittal split osteotomy (BSSO) is to take into account the correct position of the condyle. Adjustable plates can be used to fine-tune the final occlusion without changing the osteosynthesis. A new type of adjustable plate is presented in this article. The aim is to assess the mechanical reliability of this system during the surgery and during the healing period, thanks to a preliminary prospective on 15 consecutive cases. MATERIAL AND METHODS: The bridge of the plate studied here has an "S"-shape and can be bent in two different planes. Fifteen patients presenting a maxilla-mandibular disharmony have been operated on with this device. Clinical results were evaluated three months postoperatively and the mechanical reliability of the device was studied prospectively from teleradiographies of 15 patients operated on in our department. RESULTS: This study shows good results, with respect to the mechanical reliability of this S-shaped adjustable plate, three months postoperatively corresponding to the bone-healing period. Radiographic observations did not show any significant displacement at the osteosynthesis site. DISCUSSION: This preliminary study shows the mechanical reliability of this new S-shaped adjustable plate. Its semi-rigid character may allow for certain condyle position adaptability. No plate fracture was reported for this 15 patient series. These encouraging results have to be confirmed on a larger series.

Management of patients with sickle cell disease in oral surgery. Literature review and update.

Sickle cell disease, the most common genetic disease in the world, is a chronic hemolytic disease that can be complicated by severe vaso-occlusive pain crises resulting in tissue necrosis and even death. Due to its increasing incidence, oral surgeons will inevitably be faced with the management of these patients. To limit the risk of crises, our goal is to share recommendations for the management of sickle cell patients in oral surgery. The vaso-occlusive crises (VOC), heart attacks and chronic anemia endured by these patients cause chronic lesions in various organs. Complications include retinal disease, avascular necrosis, priapism, neurological involvement (cerebrovascular accident), cardiomyopathy, lower limb ulceration, renal and hepatic dysfunction, and cardiopulmonary disease. These complications inevitably lead to an increase in mortality rate. Thorough knowledge of this pathology is essential for the management of these patients in oral surgery. Management strategies include prevention and diagnosis of oral lesions related to sickle cell disease and its treatment, as well as methods of preparation and execution of oral surgery procedures. We suggest guidelines for the management of these complications and implementation of preoperative, intraoperative and postoperative surgical protocols for both practitioners and patients.

Proteolysis of rat IgG subclasses by Staphylococcus aureus V8 proteinase.

Monoclonal IgG belonging to the four rat IgG subclasses (IgG1, IgG2a, IgG2b, IgG2c) and some IgG subclasses from normal rat serum were subjected to enzymatic degradation with Staphylococcus aureus V8 proteinase. The results show that only one subclass, IgG2b, is significantly cleaved by the enzyme, with the release of two main products identified as F(ab)2 and Fc-like fragments. This unique susceptibility of the IgG2b subclass represents therefore an easy means of identification and also offers a simple procedure for a preparation of F(ab)2 fragments from monoclonal IgG2b antibodies.

Studies of the IgE binding sites to rat mast cell receptor with proteolytic fragments and with a monoclonal antibody directed against epsilon heavy chain: evidence that the combining sites are located in the C epsilon 3 domain.

The binding sites of rat IgE to mast cell receptor were investigated by the use of proteolytic fragments and a monoclonal antibody to epsilon chain (MARE-1). Three main fragments were characterized by short-time papain digestion of IgE: F(ab')2-E, a fragment related to the C, 4 domain, and an asymmetric fragment corresponding probably to an IgE molecule with one proteolyzed C, 3 domain. Neither F(ab')2-E nor C, 4 could interfere with the binding of IgE to rat mast cells. These two fragments did not show significant polymerization upon heating at 56 degrees C, while large amounts of polymers were produced from whole IgE, MARE-1 monoclonal antibody was found to react neither with F(ab')2 nor with C, 4, thereby suggesting its interaction with the C, 3 domain. MARE-1 was found to inhibit partially (about 55%) the binding of IgE to its receptor. Taken together the results indicate that the binding sites of IgE to rat mast cell receptor are located within the C, 3 domain. In addition, isolation of the C, 4 domain will be useful to evaluate its participation in the affinity of IgE to receptors of other cells such as lymphocytes or macrophages.

Isolation and characterization of a VH domain fragment from monoclonal rat IgG of IgG1 and IgG2a subclasses.

Digestion with trypsin of monoclonal rat IgG of IgG1 and IgG2a subclasses produced two fragments, isolated only in dissociating media. The larger fragment (mol. wt. 120,000 Da) was comprised of the two light chains covalently bound to shortened gamma chains. Amino acid sequence of the shortened gamma chain indicated that the site of cleavage is located at the beginning of the C gamma 1 domain at a position homologous to residue 139 of mouse gamma heavy chain of IgG1 MOPC 21. The smaller fragment (mol. wt. 13,000 Da) was found to consist of the entire variable domain of the heavy chain and probably a short stretch of the C gamma 1 domain. The unique susceptibility of rat monoclonal IgG1 and IgG2a is likely to be the result of the presence of a lysine residue in a loop of C gamma 1 domain, which therefore is accessible to trypsin. Tryptic cleavage of rat monoclonal antibodies of IgG1 and IgG2a subclasses can be considered as a simple method to produce a fragment related to the VH domain.

The immune response to synthetic peptides of human protamines HP1 and HP2.

Peptides representing the amino-terminal sequence of protamines HP1 (sequence 1-12) and HP2 (sequence 1-11), the two major nuclear proteins of human sperm, have been synthesized. Rabbits were immunized either with peptide conjugated with a carrier or with free peptide. The resulting antisera were examined for their capacities to bind the homologous peptide, other peptides from protamines HP1, HP2, from ram protamine, a protein resembling HP1, and finally with the whole protamine. Only free peptides were immunogenic. Antisera were found to react with the homologous peptide, but also with some other peptides. More especially, antibodies to peptide HP1 1-12 were found to recognize an epitope shared by the homologous peptide, peptide HP1 37-49 and peptide 1-12 of ram protamine. The common antigenic determinant seems to depend on the conformation of the peptides, rather than strictly related to common sequences. Anti-peptide antibodies react poorly and in a non-specific manner with the parent protein. The failure of reactivity with the protamines strongly suggest that these small basic proteins are folded and probably globular molecules in contrast with the totally random model postulated by several previous works.

Differential reduction of the inter-chain disulfide bonds of rat immunoglobulin E: relation to biological activity.

Monoclonal rat IgE was reduced over a range of dithiothreitol (DTT) concns. The number of disulfide bonds reduced and their location in the IgE molecule were studied. One millimolar DTT was found to split the two inter-heavy-chain disulfide bonds of the C epsilon 2 domain while increasing DTT concn to 10 mM split the two inter-heavy-light-chain disulfide bridges. Therefore, the sensitivities to reduction of disulfide bonds in rat IgE were found to be the opposite of those in human IgE. In addition, the results indicated the absence, in rat IgE, of the intra-epsilon-chain labile disulfide bond of the C epsilon 1 domain, which is reduced by 2 mM DTT in human IgE. Circular dichroism studies showed significant modifications, mainly of tertiary structure, for rat IgE reduced with 10 mM DTT, but not for IgE reduced with 1 mM DTT. The ability to block passive sensitization with reaginic antibody was not modified when IgE was reduced with 1 mM DTT (which split the two inter-heavy-chain disulfide bonds), but was lost when inter-heavy-light-chain bridges were reduced with 10 mM DTT. In addition, a non-covalent epsilon-chain dimer was found to have the same blocking activity as native IgE (or IgE reduced with 1 mM DTT). Therefore, the results suggest that reduction of most or all the inter-chain disulfide bonds, in rat as in human IgE, induces changes in quaternary structure, more especially in the relationship between the Fab and Fc parts of the molecule, leading to steric blockade, by Fab, of the binding sites for mast cells present on Fc.

Conformational studies of rat monoclonal immunoglobulin E.

Two monoclonal IgEs (IR 2 and IR 162) were studied in terms of their conformational features by circular dichroism and differential u.v. absorption. The studies were performed both on the native proteins and under different conditions known to affect the biological properties of IgE (heating at 56 degrees C, acid pH, and presence of reducing agents). Whereas IgE IR 162 appeared to undergo significant conformational changes upon heating and at acid pH, IgE IR 2 was found to be unaffected or less affected by these treatments. The two monoclonal IgEs were found to be equally effective in blocking passive sensitization by IgE antibodies. However, the blocking capacity of IgE IR 162 was affected much more by heating at 56 degrees C than that of IgE IR 2.

Auto-antibodies to human sperm basic nuclear proteins in infertile and vasectomized men: characterization of antigens and epitopes recognized by antibodies.

The sera of vasectomized men and of patients with immune infertility were used to study the antigens and epitopes of sperm nuclear proteins that bind antibodies in these sera. No reaction with sperm histones was observed except for one serum. P1, P2 protamines and pro-P2 protamines were recognized by auto-antibodies. Studies with peptides derived from P1 and P2 protamines and with mammalian protamines related to HP1 showed that antibodies are mainly specific for a folded protamine molecule, more especially antibodies from vasectomized men. These results disagree with the random coil model proposed for protamines by several previous works. A cross-reactivity between P1 and P2 protamines was observed only for the whole molecules and not for peptides derived from them. This observation suggests that the two classes of protamines, different in sequence, may have a similar folding and thereby may be functionally equivalent.

Optimal conditions for the preparation of Fab and F(ab')2 fragments from monoclonal IgG of different rat IgG subclasses.

The optimal conditions for the preparation of Fab and F(ab')2 fragments from monoclonal rat IgG of different subclasses are described. Digestion of IgG for 2-4 h at 37 degrees C with 1% (w/w) papaïn at pH 7.0 in the presence of 0.01 M cysteine leads to almost complete cleavage into Fab and Fc fragments. Fab fragments are isolated by sequential chromatography on Ultrogel AcA 44 and on DEAE-cellulose columns. In the case of IgG2c subclass, Fab fragment may be directly isolated by chromatography on Protein A-Sepharose. Production of F(ab')2 fragments from rat IgG1 and IgG2a is obtained with best yield by treatment at acid pH (pH 2.8) before incubation with 1% (w/w) pepsin at pH 4.5 for 4 h at 37 degrees C. For monoclonal IgG2b the best procedure is incubation with S. aureus V8 protease at pH 7.8 (4 h at 37 degrees C with an E/S ratio of 1/30 (w/w]. The best yield of F(ab')2 from monoclonal IgG2c is obtained by incubation for 4 h at 37 degrees C with 1% (w/w) pepsin. F(ab')2 fragments (or the F(ab)2-like fragment released by digestion of IgG2b with S. aureus V8 protease) are isolated by gel filtration on Ultrogel AcA 44.

A novel method to label liposomes with 99mTc by the hydrazino nicotinyl derivative.

UNLABELLED: In this study a new 99mTc labeling method for polyethyleneglycol (PEG)-coated liposomes is described. The in vitro and in vivo characteristics were compared with the conventional 99mTc-HMPAO-labeled PEG-coated liposomes. METHODS: PEG-coated liposomes were labeled with 99mTc by the hydrazino nicotinyl (HYNIC) derivative of distearoylphosphatidyl-ethanolamine (DSPE) and compared with PEG-coated liposomes labeled with 99mTc-HMPAO. In vitro stability tests were performed. Biodistribution and imaging characteristics of both liposomal preparations were determined in rats with Staphylococcus aureus infection in the left calf muscle. RESULTS: Per liposome, 230 hydrazine groups were incorporated. The labeling efficiency of the 99mTc-HYNIC liposomes was greater than 95%, so no postlabeling purification was required, in contrast to the 99mTc-HMPAO liposomes. The 99mTc-HYNIC liposomes showed greater in vitro stability than the conventional 99mTc-HMPAO liposomes. Abscess uptake of the 99mTc-HYNIC liposomes was significantly greater (1.74+/-0.38%ID/g versus 1.26+/-0.29%ID/g, 24 h postinjection, P < 0.03). Furthermore, kidney uptake of the 99mTc-HYNIC liposomes was one third of the uptake of the 99mTc-HMPAO liposomes (0.79+/-0.07%ID/g versus 2.47+/-0.35%ID/g, 24 h postinjection, P < 0.0001). CONCLUSION: This new 99mTc-HYNIC-based labeling method for liposomes is rapid, efficient and easy to perform. Most importantly, the 99mTc-labeled liposomes have an improved stability and in vivo characteristics. The new labeling method is a major step forward toward a radiopharmaceutical for infection imaging that can be prepared in a one-step procedure within 15 min at room temperature and thus can be applied in every routine clinical practice.

Clot accumulation characteristics of plasminogen-bearing liposomes in a flow-system. Groningen Utrecht Institute for Drug Exploration.

In this study, the clot accumulation properties of liposome-coupled plasminogen were compared to those of free (non-liposomal) plasminogen in an in vitro, closed-loop, flow-system. After introduction of a clot into the closed system, double-radiolabelled plasminogen-liposomes were administered and the accumulation of radiolabel on the entire clot was measured. Liposomal plasminogen showed improved accumulation over free plasminogen, on both a fibrin clot and a whole blood clot. Moreover, once liposomal plasminogen was fibrin associated, it could not be washed away with buffer, in contrast to free plasminogen. Liposomal plasminogen was able to compete successfully with an excess of free plasminogen. The plateau levels for the accumulated amount of plasminogen depended on the incubated amount of plasminogen and were influenced by partial degradation of the clot. Furthermore, it was shown that a threshold liposomal plasminogen surface-density was needed for optimum clot accumulation.

Fibrin binding of plasminogen coated liposomes in vitro.

In this study, the fibrin binding properties of liposomes containing a number of plasminogen (Plg) molecules on the outside were compared to those of free (non-liposomal) Plg in an in vitro model system. Fibrin monolayer coated 96-wells plates were used, containing fibrin monomer at a density of around 3.4 to 3.9 x 10(-4) nmol/cm2. These densities are similar to liposomal Plg-densities, thus allowing multivalent interactions to occur. In the panel of experimental conditions that was chosen, binding of free Plg and liposomes with Plg showed three main differences in characteristics. Firstly, in the fibrin binding of Plg-liposomes not all Plg may be involved, but on the average 40% of the total amount of liposomal Plg. This was shown by lysing the liposomes after binding to the fibrin and estimation of truly bound Plg. With Plg-densities on the liposomes below the fibrin binding sites density, the maximal number of bound Plg molecules remains below the amount of available fibrin binding sites. Secondly, a higher binding rate by at least one order of magnitude was observed for liposomes with Plg compared to free Plg. Thirdly, liposomes with Plg exhibit a fibrin binding affinity which increases with Plg-density, because of the multivalent character of interaction. Liposomal Plg can successfully compete for fibrin binding sites with a 100 fold higher concentration of free Plg. These in vitro findings indicate that in view of avid and rapid fibrin binding, liposomes with attached plasminogen may be suitable for in vivo targeting to fibrin based thrombi.

Thrombolytic treatment with tissue-type plasminogen activator (t-PA) containing liposomes in rabbits: a comparison with free t-PA.

In this study, we aimed at improving the therapeutic index of tissue-type Plasminogen Activator (t-PA) as thrombolytic agent in the treatment of myocardial infarction. Liposome-encapsulated t-PA was tested in a rabbit jugular vein thrombosis model: administration of free t-PA (t-PA) as a bolus injection in the ear vein was compared to a similar administration of liposomal t-PA (t-PA-lip), liposomal t-PA in plasminogen-coated liposomes (Plg-t-PA-lip), a mixture of free t-PA and empty liposomes (t-PA+ empty lip) and a saline-blank (blank) in terms of thrombolytic activity and side effects. Liposomal t-PA (t-PA-lip/Plg-t-PA-lip) showed a significantly better thrombolysis efficiency than equimolar doses of free t-PA (t-PA/ t-PA+ empty lip): about 0.24 mg/kg of liposomal t-PA practically equalled the lysis-activity of a dose of free t-PA of 1.0 mg/kg (t-PA1mg/kg). On the other hand, liposome encapsulation did not affect the systemic activation of alpha 2-antiplasmin and plasminogen by t-PA. We conclude that for this model an improvement in thrombolytic efficacy of t-PA is achieved by liposome encapsulation of t-PA. As t-PA-lip and Plg-t-PA-lip -treatment induced similar results, targeting of liposomal t-PA by coupled glu-Plg remains a topic to be optimized in future studies.

Tryptic cleavage of rat IgG: a comparative study between subclasses.

Monoclonal rat IgG belonging to the 4 rat IgG subclasses, and some IgG subclasses isolated from normal rat serum were subjected to enzymatic degradation with trypsin. Differences in the products of tryptic digestion were observed according to the IgG subclass. IgG2b and IgG2c were degraded mainly into Fab and Fc fragments. IgG1 and IgG2a appeared resistant to such cleavage. However, tryptic digestion of the latter two produced two fragments separated only in dissociating media. Results of the studies suggest that one of the fragments (mol. wt. 13,000) probably consists of most of the variable domain of the gamma heavy chain, while the second (mol. wt. 120,000) consists of the IgG deleted of the VH regions.

Trace metals in occupationally and nonoccupationally exposed individuals.

An epidemiological survey was conducted in Houston, Texas on five trace metals in policemen, parking garage attendants, women living near freeways and three control groups of subjects. The controls were matched with the exposed groups for covariate information such as age, sex, smoking habits, ethnic background, socioeconomic status, hair color, and education. Each subject was sampled four times for blood, urine, hair, and feces, and these samples were analyzed for lead, cadmium, zinc, manganese, and copper. Lead and cadmium were correlated with airborne exposures but zinc, manganese and copper were not. The second part of this paper deals with a market study of platinum and palladium markets and a design of an epidemiology survey of individuals occupationally and nonoccupationally exposed to these two metals. The market survey shows that although the catalytic muffler will have a major impact on the market, it is predicted that producers can meet these demands.