Reduced susceptibility to amoxicillin of oral streptococci following amoxicillin exposure

As antibiotic pressure often triggers bacterial resistance, the use of short-duration therapies is increasingly recommended. The objective of the present study was to evaluate both the clinical efficiency and the impact on oral streptococci of a 3 day versus a 7 day amoxicillin therapy for odontogenic infection requiring tooth extraction. On day 0, patients were randomly assigned to a 3 day or 7 day amoxicillin treatment. The tooth was extracted on day 2 and the post-operative follow-up was carried out on day 9. Oral flora was collected on days 0, 9 and 30, and the susceptibility of the streptococci to amoxicillin was determined. The results showed that treatment with amoxicillin for 3 or 7 days had a similar clinical efficiency, and also induced similar selection of oral streptococci with reduced susceptibility to amoxicillin, suggesting that the selection of strains with reduced susceptibility to amoxicillin is a rapid phenomenon, appearing even with short-duration therapies.

Amelogenin gene splice products A+4 and A−4 implanted in soft tissue determine the reorientation of CD45-positive cells to an osteo-chondrogenic lineage

Several molecules such as bone morphogenetic protein-7, bone sialoprotein (BSP), or amelogenin gene splice products (A+4 or A-4) have been shown to induce reparative dentin formation in a rat model. However, at the moment, the origin and the mechanism of differentiation of the pulp cells stimulated by the bioactive molecules remain poorly understood. The present investigation was undertaken to validate an ectopic oral mucosal mouse model to evaluate the effects of amelogenin gene splice product implantation in a non-mineralizing tissue. Agarose beads, alone or coated with amelogenin gene splice products, were implanted in the mucosa of the cheeks in mouse. An immunohistochemical characterization of the recruited cells was undertaken for 3 days, 8 days, and 30 days after the implantation. The results showed that the implantation of agarose beads in mucosa induced the recruitment of inflammatory CD45 positive cells. When the beads were coated with amelogenin gene splice products (A+4 or A-4), the expression of osteo-chondrogenic markers (RP59, Sox9, or BSP) was also observed. However, no mineralization nodule was observed, even after 30 days of implantation. The present investigation suggests that amelognin gene splice products have the capacity of recruiting among inflammatory cell mesenchymal progenitors that eventually differentiate into osteo-chondrogenic cells. Altogether, the results obtained in the pulp model and the present data suggest the existence of different pathways of cell recruitment and differentiation in different cellular environments.

Lipid transfer protein 1 is a possible allergen in Arabidopsis thaliana

BACKGROUND

The Arabidopsis thaliana genome was recently fully sequenced, and this plant is now considered as the most useful model to study the effects of genetic engineering. The aim of the present study was to identify A. thaliana IgE-binding molecules and to localize their genes in order to evaluate the potential effect of gene insertion on the expression of IgE-binding molecules.

METHODS

A. thaliana flower proteins were separated by two-dimensional gel electrophoresis and transferred onto a nitrocellulose sheet. The nitrocellulose sheet was successively incubated with human sera known to contain IgE that binds to rapeseed proteins, alkaline phosphatase-conjugated goat anti-human IgE and 5-bromo-4-chloro-3-indolyl phosphate and nitroblue tetrazolium. One allergen was further identified by N-terminal amino acid microsequencing.

RESULTS

The results showed that some individuals possessed IgE that recognized numerous proteins with high molecular masses and various isoelectric points. This binding pattern strongly suggests that the epitopes recognized by these IgE could be, at least partly, sugar residues. Otherwise, out of the 10 sera that possessed IgE to Arabidopsis flower proteins, one serum strongly recognized a unique basic protein with an apparent molecular mass of around 14 kD. This protein was identified by amino acid microsequencing as the lipid transfer protein 1 (LTP1).

CONCLUSION

We have demonstrated that A. Thaliana LTP1 is IgE reactive. The gene encoding this protein is located on chromosome 2, but it has been described that family 1 of A. Thaliana LTPs constitutes a multigenic family with genes located on various chromosomes.

Polygalacturonase (pectinase), a new oilseed rape allergen

BACKGROUND

Type I hypersensitivity to rapeseed pollen allergens was described as the result of a cross-sensitization with various pollens that could constitute an aggravating factor in birch or grass pollen allergies. Recently, a few rapeseed pollen allergens were described. The aim of the present work was to identify new rapeseed pollen allergens by using two-dimensional gel analysis, microsequencing, and mass spectrometry.

METHODS

Water extractable proteins from oilseed rape pollen or stamen were separated by two-dimensional gel electrophoresis. The proteins were then electroblotted onto a nitrocellulose (NC) sheet. The NC sheets were successively incubated with (1) individual human sera pre-selected for their immunoglobulin E (IgE) reactivity to rapeseed pollen proteins, (2) alkaline phosphatase (AP)-conjugated goat anti-human IgE and (3) AP substrate. The allergens localized by this method were then identified by microsequencing and MALDI-TOF mass spectrometry analysis.

RESULTS

Of the 18 sera studied, five recognized a wide multispot zone with a molecular mass around 43 kD and pIs between 6.5 and 8.5. The results obtained with two representative sera are shown. From this zone, two isoforms of the polygalacturonase enzyme were identified by microsequencing. Confirmation was obtained through MALDI-TOF mass spectrometry analysis.

CONCLUSION

The present results allow the identification of a new rapeseed allergen that can be the main allergen for some patients.

Development of enamel defects in rat mandibular incisor after thyro-parathyroidectomy

Previous studies with scanning electron microscopy (SEM) demonstrated the presence of small hypoplastic defects in the incisal third of incisors and deep hypoplasia in the apical third of the incisors after thyro-parathyroidectomy in the rat. These studies provided a morphological description of the defects, but uncertainty remained concerning their development throughout amelogenesis. The aim of the present investigation was to study, with SEM operated in the backscattered mode, the development of the hypoplastic defects, from the beginning of the secretion to the end of the maturation zone of the enamel, in the lower incisor of thyroparathyroidectomized rats. The results of the present study showed that the large and small defects developed are separate entities that do not develop into the other. The distribution of large defects might be linked to a reduction of the eruption rate in these rats. The pathogenesis of these defects needs further investigation.

Interest of two-dimensional electrophoretic analysis for the characterization of the individual sensitization to latex allergens

BACKGROUND/OBJECTIVE

Latex allergy is a type 1 hypersensitivity reaction that mainly affects high-risk populations such as health care workers, spina bifida-affected or multiply-operated children. Ten molecules have so far been identified and registered as latex allergens (Hev b 1 to Hev b 10). The aim of the present investigation was to identify the major latex allergens by an individual analysis of the IgE response of latex-allergic patients to latex proteins separated by two-dimensional (2-D) gel electrophoresis.

MATERIALS AND METHODS

Latex proteins from a sap or a glove extract were separated by 2-D electrophoresis and transferred to a nitrocellulose membrane. Each membrane was incubated with the serum of one latex-allergic patient. The most frequently recognized latex allergens were characterized in sap and glove extracts using monoclonal antibodies or amino acid microsequencing.

RESULTS

The one-dimensional screening of 54 patient sera revealed 4 major bands recognized by IgE. The 2-D analysis of the sensitization to latex allergens allows the identification of allergen isoforms and the characterization of an individual response diversity. Hev b 6.01 was recognized by 88.9% of the patients. Protein spots around 14 kD were recognized by 48.1% of the patients and corresponded to Hev b 6.03 as well as other proteins. A not yet characterized doublet of acidic proteins with molecular masses of 43 and 94 kD was recognized by 20.4% of the sera. Only 5.5% of the sera did not recognize any of these 4 major allergens. Hev b 1 is the main protein from the glove extract but was not constantly found in sap extracts.

CONCLUSIONS

One-dimensional electrophoretic analysis of the allergen is usually not sufficient to characterize the individual specificity of the IgE response to latex allergens. Latex-glove proteins which are allergens can be absent from the sap extracts and the sensitization to these allergens could be underestimated. Individual 2-D analysis of the sensitization to latex allergens is useful to define the best allergen mixture required for diagnosis and needed for individual therapy monitoring.

Characterization of high-molecular-mass allergens in oilseed rape pollen

BACKGROUND

Oilseed rape pollen allergies have been previously described as the result of cross-sensitization with various pollens. Recently, several proteins have been identified as oilseed rape allergens. The aim of the present work was the characterization of oilseed rape pollen allergens by two-dimensional (2-D) gel analysis and amino acid microsequencing.

METHODS

Water extractable proteins from oilseed rape pollen were separated by isoelectrofocusing and then transferred onto a nitrocellulose sheet. Twenty-one human sera from pollen- or mustard-allergic individuals were screened for their reactivity to oilseed rape proteins. Eleven sera possessed IgE which recognized oilseed rape pollen proteins and one serum was selected for further 2-D characterization and amino acid microsequencing of the allergens.

RESULTS

The results showed that three molecules from oilseed rape pollen were identified as oilseed rape allergens which have not yet been described. These three proteins were molecules of 70 kD with a pI >8, 40 kD with a pI around 10 and 80 kD with a pI around 5. These proteins displayed identities with the berberine bridge protein, a receptor-like protein kinase and the cobalamin-independent methionine synthetase from Arabidopsis thaliana, respectively. The genes encoding the putative Arabidopsis molecules are located on chromosome 1 (berberine bridge protein) and chromosomes 3 and 4 (receptor-like protein kinases).

CONCLUSION

These results show that certain high-molecular-mass proteins from oilseed rape pollen are allergens.

Identification of Hev b1 in natural latex mattresses

BACKGROUND

Type 1 hypersensitivity to natural rubber latex proteins is a well-recognized health problem. Recent data have shown that allergens can be extracted from natural latex mattresses. As Hev b 1 (rubber elongation factor) and Hev b 6.02 (hevein) were described as major allergens, the present work was carried out to evaluate their presence in latex mattresses as well as in latex gloves.

METHODS

Extracted proteins from latex mattresses and gloves were separated by SDS-PAGE or two-dimensional gel electrophoresis, transferred onto nitrocellulose and detected with monoclonal antibodies specific for Hev b 1 and Hev b 6.02.

RESULTS

The results showed that various forms of Hev b 1, as well as degradation products of Hev b 1 were detected in latex mattresses and gloves, whereas Hev b 6.02 was not detected either in mattresses or in gloves. In a standardized latex extract, Hev b 1 and Hev b 6.01 (prohevein) were identified by the monoclonal antibodies.

CONCLUSION

The fact that only Hev b 1 was detected by immunoblot in latex articles indicates that Hev b 1 may be the last protein to be washed out of latex products and that the Hev b 1 content may be used as a criterion for the estimation of the allergenicity of the latex products.

Protein and allergen analysis of latex mattresses

BACKGROUND

Latex allergy is a well-recognized health problem. The wide use of latex in daily life raised the question whether latex articles could be a source of allergens. The present study was carried out to analyse various latex mattresses for protein and allergen characterization.

METHODS

Five latex foam mattresses were reduced to powder and proteins were extracted using either water or urea. The protein content of the extracts was analyzed by SDS-PAGE, IEF, 2-D gel electrophoresis and amino acid sequence analysis. The presence of specific IgE, directed toward mattress proteins found in human sera of latex-allergic patients, was tested using ELISA and immunoprints.

RESULTS

The results showed that no protein or allergen could be extracted from synthetic foam. However, depending on the type of mattress and extraction procedure, various quantities of proteins could be extracted from mattresses containing natural latex. The ELISA levels of various latex-allergic patients were always more significant against urea extracts than against water extracts, except for one mattress. The protein and allergen patterns were qualitatively similar for all mattresses containing natural latex. Hev b 1 was identified by N-terminal amino acid sequence analysis.

CONCLUSION

Because the natural rubber of the mattresses contains latex allergens, these allergens are a potential source of sensitization and could constitute a risk, at least to allergic individuals.

Scanning electron microscopy and energy-dispersive X-ray analysis of defects in mature rat incisor enamel after thyroparathyroidectomy

The surface and the structure of the erupted enamel of the continuously growing rat incisor were studied by scanning electron microscopy (SEM) to analyse the effect of thyroparathyroidectomy on enamel formation. Ten male 21-day-old Wistar rats were thyroparathyroidectomized and five sham-operated rats were used as controls. Two months after surgery the rats were perfused with 1% glutaraldehyde and their mandibles dissected. The erupted ends of the incisors were cut off and routinely processed for SEM. An energy-dispersive analysis of X-rays (EDX analysis) was performed for the calcium:iron ratio of the enamel surface defects. Thyroparathyroidectomy induced surface defects and structural abnormalities in the outer layer of the mature erupted enamel. It was established that the surface and structural defects were related. The EDX analysis of the outer enamel showed that the enamel defects were associated with an abnormal elevation of the iron content. The SEM appearance and the EDX analyses indicated that these defects were hypomineralized and rich in iron. The reddish colour of the enamel is due to the high concentrations of iron.

Morphological study of amelogenesis in the rat lower incisor after thyro-parathyroidectomy, parathyroidectomy and thyroidectomy

The effects of thyro-parathyroidectomy, parathyroidectomy or thyroidectomy upon enamel formation in the rat incisor were studied. One control group and four groups of surgically treated rats were used: parathyroid autotransplanted, thyroidectomized, parathyroidectomized, and thyro-parathyroidectomized. One month after surgery, the incisors were processed for light and electron microscopy. The present study revealed perturbations of the Tomes process morphology, of the rod pattern in the inner enamel formation, of the enamel surface, and of the mineralization after thyro-parathyroidectomy. After parathyroidectomy, only mineralization defects could be visualised. No effects were observed in enamel after thyroidectomy. A severe hypocalcemic state as seen in thyro-parathyroidectomized rats affects the enamel shape, and mineralization, and the morphology and function of secretory ameloblasts. Knowledge of the way in which the alteration of the enamel surface is produced should contribute to a better understanding of the development of tooth enamel.

Dental mineralization

Extracellular matrix components and cell-derived microstructures are implicated in mineralization processes which occur in dental tissues. The respective role(s) of collagenic and non-collagenic matrix components are reviewed: phosphorylated and non-phosphorylated proteins, proteoglycans and phosphpholipids. Space-filling amphiphilic molecules seem to play an important role in the preorganization and oriented deposition of calcium phosphate on structures serving more or less as passive support in dentine as well as in enamel.

Effects of thyro-parathyroidectomy and parathyroidectomy upon dentinogenesis: Part I: Light microscopy

In order to determine the differential effects of the thyroid hormones and the parathyroid hormone upon dentinogenesis in the rat incisor one control group (C) and four groups of surgically treated rats were studied: parathyroid autotransplanted (PTT), thyroidectomized (TX), parathyroidectomized (PTX), and thyro-parathyroidectomized group. One month after surgery the incisors were dissected and the tissues were prepared for light microscopy and morphometric measurements. This study revealed modifications in the TPTX rats as well as in the PTX rats: an enlargement of the predentin, alterations in the predentin appearance and the presence of mineralization defects. These results confirm that the effects observed are probably due to a PTH deficiency and/or hypocalcemia and suggest that their occurrence is associated with a determined stage of dentinogenesis in the rat.

Effects of thyro-parathyroidectomy and parathyroidectomy upon dentinogenesis: Part II: Electron microscopy

An ultrastructural study was carried out in order to better characterize the findings observed in the first part of our study. The materials and methods are the same as those used in the preceding paper. This study reveals the occurrence of structures which display a symmetrical cross-banded pattern within the predentin and dentin of thyro-parathyroidectomized (TPTX) and parathyroidectomized (PTX) rats. A difference in the distribution of the symmetrical banded structures as dentinogenesis advances, as well as differences in the amount of the symmetrical banded structures between TPTX and PTX rats were observed. The symmetrical banded structures correspond with the so-called symmetrical SLS previously described in the incisor of normal and pathologic rats. The occurrence of these structures at a given stage of the incisor development suggests that the odontoblast is sensitive to the parathyroid hormone deficiency and/or hypocalcemia in a precise stage of its maturation.

Structural variations of different oral basement membranes revealed by cationic dyes and detergent added to aldehyde fixative solution

The ultrastructural appearance of different types of basement membrane was studied using histochemical methods for visualizing glycosaminoglycans. Samples of rat gingiva and mouse molar germ tissue were fixed either with glutaraldehyde, glutaraldehyde-ruthenium hexammine trichloride (RHT), glutaraldehyde-Cuprolinic Blue (CB) or cetylpyridinium chloride-glutaraldehyde (CPC). Ultrathin sections were stained with uranyl acetate and lead citrate. The results showed that the conventional trilaminar structure of the basement membrane was observed after glutaraldehyde and CB fixation. In contrast, after CPC or RHT fixation, the appearance of the basement membrane was homogeneous without any evidence of a lamina lucida. Furthermore, after single fixation with CPC, the ultrastructure of different basement membranes from oral tissues showed some differences in appearance which were related to their localizations, functions, or both.

Immunolocalization of a 110 kD molecule and a 150 kD molecule in rat incisor and mandibular bone

In the present study, antibodies against rat dental proteoglycans were used to characterize and localize the proteoglycans in rat incisor and mandibular tissues. Polyclonal rabbit antibodies were raised against a CPC-precipitated fraction of a sulfated dental extract. In unpurified dental extract these antibodies recognized two molecules of 110 kD and 150 kD. The 150 kD molecule was susceptible to chondroitinase ABC digestion but the 110 kD molecule resisted this enzymatic degradation. Immunocytochemically these two molecules were seen to be located in the pulp, the enamel organ and the mandibular bone. In each tissue only the periphery of the cells was stained and not the intracellular compartment. In the mineralized area of bone, dentin and forming enamel no staining was seen. These results indicate common epitopes in the proteoglycans from pulp, predentin, enamel organ and bone. Some differences were found in the nature of tooth and bone proteoglycans.

Visualization of glycosaminoglycans in rat incisor extracellular matrix using a hyaluronidase-gold complex

The enzyme-gold technique was used on dental tissues. Hyaluronidase was complexed with gold, and ultrathin sections of rat incisors were incubated with the hyaluronidase-gold complex to localize chondroitin-sulphate and hyaluronic acid at the ultrastructural level. The hyaluronidase-gold complex was found in predentine and dentine, especially at the mineralization front, in interglobular spaces and around dentinal canaliculi. The very young enamel was labelled, but not the later stages of formation. This method allowed a very precise localization of hyaluronic acid and/or chondroitin sulphate in rat incisors extracellular matrices. These findings support the important role of glycosaminoglycans in dentine mineralization.

Visualization of glycosaminoglycans in rat incisor predentin and dentin with cetylpyridinium chloride-glutaraldehyde as fixative

Using cetylpyridinium chloride (CPC) in glutaraldehyde as fixative, we observed sinuous fiber-like structures 300-500 nm long and 7-14 nm thick in the spaces between the collagen fibers of rat incisor predentin. Small granules and fibrils were also detected. Electron-dense vesicles were seen inside the odontoblast processes. The plasma membrane was irregularly stained with material that adhered to its surface. In demineralized dentin, needle-like structures were seen at the periphery of globular structures which were not stained. Staining the sections with Alcian blue did not greatly improve the visualization of CPC-precipitated glycosaminoglycans. The specificity of staining was assessed on serial sections by selective dissociation of glycosaminoglycan aggregates with 2 M calcium chloride and their digestion by bovine testicular hyaluronidase. The glycosaminoglycans were probably combined with lipids, because treatment of the sections with a chloroform/methanol mixture removed the CPC-induced precipitates from both predentin and dentin.

Effect of tunicamycin on glycogen accumulation in the stratum intermedium and odontoblasts of rat incisor

Repeated injection of rats with tunicamycin over two days induced a 1- to 5-fold increase in glycogen. This accumulation occurred in the stratum intermedium of the enamel organ and in young secretory odontoblasts. In rats injected over 3 days, the number of glycogen particles was at least 10 times larger than in control rats, and large glycogen accumulations were observed in the cytosol of these two groups of cells. These results were obtained by staining with periodic acid-thiocarbohydrazide and silver proteinate, a specific method for the detection of glycoconjugates containing vic-glycol groups. The existence of a relationship between these local cytosolic accumulations of glycogen and the developmental stage of certain groups of cells was shown by the changes that occurred in glycogen distribution. The present results suggest that the stratum intermedium supplies energy for precursor transport.

Characterization of axolotl heavy and light immunoglobulin chains by monoclonal antibodies

Axolotl specific antibodies to 2,4-dinitrophenyl (DNP) were purified by affinity chromatography from the sera of animals immunized with 2,4,6-trinitrophenylated sheep red blood cells (TNP-SRBC). The purified anti-TNP/DNP antibodies, when analyzed by SDS-PAGE, were constituted of high molecular weight molecules, which in reducing conditions, were separated into heavy 72-88 kD and light 27-30 kD polypeptides. The axolotl heavy antibody chains strongly bound Concanavalin-A and migrate faster in SDS-PAGE after endoglycosidase-F (Endo-F) treatment. Using the same techniques, no carbohydrate components were detected onto light chains. Monoclonal antibodies (MAbs) were obtained against these purified axolotl immunoglobulins (Ig) and their specificities were studied by immunoblotting. MAbs 33.45.1 and 33.101.2 respectively recognized heavy and light chains determinants of the Ig molecule. These determinants were resistant to Endo-F digestion, suggesting that the two MAbs were not directed to polypeptide-associated N-linked high mannose or complex oligosaccharides. MAbs 33.45.1 and 33.101.2 were compared to 11.5.2, an anti-axolotl thymocytes MAb which was reactive for both axolotl leucocytes and soluble Ig. MAb 11.5.2 reacted in immunoblotting against several high molecular weight axolotl serum proteins, including heavy Ig chains. Light chains were not recognized. However, 11.5.2 did not further recognize Endo-F treated Ig, suggesting its specificity for a carbohydrate determinant of the heavy chain, and link to a large diversity of soluble or membrane glycoproteins.