Ciliated fibroblasts in mouse connective tissues: a comparison between methods for estimating their frequency.

The frequency of ciliated fibroblasts in skin, gingiva, molar and incisor periodontal ligaments and incisor enamel-related periodontium of the mouse was estimated by straight counting or by methods based on the probability of observing a basal body in relation to other cell structures. Transmission electron microscopy of ultra-thin sections mounted in single slot grids was used. The results obtained with these methods differed, but indicated that periodontal ligament fibroblasts from molars or incisors generally had a higher ciliation index than the fibroblasts from skin and gingiva. These differences may not be real since the detection of cilia and/or centriolar structures seems to depend very much upon the plane of sectioning relative to the long axis of the fibroblasts, a situation which favours the more regularly arranged periodontal fibroblasts. This arrangement makes the periodontal tissues, particularly those of rodent incisors, a valuable model for studying ciliation in vivo because of the prompt response to experimental manipulation.

Alveolar bone remodelling pattern of the rat incisor under different functional conditions as shown by minocycline administration.

Remodelling of the socket surrounding the continuously growing and erupting rat incisor was examined in teeth under normo, hyper and hypofunctional conditions. Cross-sections of the mandible were observed under fluorescence microscopy, where minocycline labelling evidenced bone remodelling. Animals had received minocycline (10 mg/day) during the experimental period. Control animals (from all three groups) received vehicle alone and samples from these animals were not fluorescent. Minocycline did not interfere with the eruption rates in any of the functional conditions studied. Normofunctional (impeded) incisors showed constant osteogenic activity in the alveolar bone facing the periodontal ligament in all regions of the incisor. Under hypofunctional (unimpeded) and hyperfunctional (impeded) conditions, osteogenesis in the region close to the alveolar crest was markedly increased in the mesial wall of the socket. The labial alveolar bone, facing the enamel-related periodontium, was almost entirely formed during the experimental period in all the groups, but in hyper and hypofunctional teeth the newly formed bone was thicker and contained a substantial amount formed before the experimental period. In the more apical regions of the socket no marked differences between the three functional conditions were found. The similar bone remodelling shown in hypo and hyperfunctional teeth might indicate that there are common factors causing this pattern. Consideration of possible factors appear to rule out the eruption rate, which is very different under these two functional conditions.

Stereological determination of the volume of the rat hemimandible tissues.

Rodent incisors are useful models to study the development and behavior of dental and periodontal tissues. Some studies require three-dimensional reconstructions of the tooth but none of the described methods yield actual volumetric data. Unlike the rat lower incisors the hemimandible can be easily isolated and its volume was determined by Cavalieri's geometrical principle. This method associated with point-counting volumetry was used to calculate the volume of the structures found in that bone mainly those related to the lower incisor. For 172 g male rats the mean volume of the hemimandible was 182.7 mm(3), statistically not different from 184.9 mm(3) the mean volume of the same hemimandibles determined by Archimedes' principle. The coefficients of error (CE) of Cavalieri's estimates for the hemimandible, incisor as a whole (the tooth itself, odontogenic region and periodontium) and bone tissue were less than 0.04. For the incisor individual tissues the CEs were usually above 0.05, however their calculated volumes are probably not different from the actual ones. The data for incisors and their periodontal tissues and for bone, because of continuous growth of these structures, are meaningful only for rats of the same gender, strain and weight range.

Ultrastructural aspects of connective tissue in hereditary gingival fibromatosis.

OBJECTIVE: The purpose of this study was to analyze the ultrastructure of gingival connective tissue from patients in one family affected by hereditary gingival fibromatosis (HGF). STUDY DESIGN: Electron microscopic examination was performed with gingival tissue from 10 patients from a Brazilian family with 132 members. Fifty of 96 persons at risk for this disorder were affected, which is consistent with an autosomal dominant pattern of inheritance. RESULTS: The extracellular matrix showed flocculent material and collagen fibrils with structural abnormalities and variation in diameter. Increased numbers of oxytalan fibers were identified; however, elastic fibers were rare in the analyzed areas. CONCLUSIONS: The structural alterations found in HGF appear similar to those described in certain other heritable collagen disorders, suggesting that HGF should be included in the group of hereditary diseases in which connective tissue alterations have a distinct pattern, in contrast to reactive fibrotic gingival enlargements with no genetic component.

Morphometric evaluation of gingival overgrowth and regression caused by cyclosporin in rats.

Cyclosporin A is a selective immunosuppressant, used in organ transplants to prevent graft rejection. Cyclosporin A can cause various side effects including gingival overgrowth. The aim of this work was to evaluate gingival overgrowth of rats treated daily with 10 mg/kg bodyweight of cyclosporin A for 60 days, as well as the regression after the interruption of treatment. All rats treated with cyclosporin A developed gingival overgrowth, with increased thickness of the epithelium, height and width of the connective tissue. The density of fibroblasts and collagen fibers also increased. Five to 90 days after the interruption of treatment with cyclosporin A, there was a progressive reduction of the gingival volume and of collagen fibers and fibroblast densities. The reduction was more pronounced in the initial periods and after 90 days did not return to the normal values.

The effect of lead on the eruption rates of incisor teeth in rats.

The effects of lead on the continuously erupting rat incisors under normo-, hyper- and hypofunctional conditions were investigated. Left lower incisors of 20 rats were rendered unimpeded (hypofunctional) by cutting them out of occlusion every 2 days; the right lower incisors of these rats were considered hyperfunctional. Measurements on normally growing teeth (normofunctional) were carried out in a group of ten rats whose teeth were not cut but only marked every 2 days. On day 7 of the experiment, half of the rats from these two groups were given a single intraperitoneal injection of lead acetate (40 mg/kg), and the other half received sodium acetate (22 mg/kg). Another group of 15 rats was used to obtain blood samples for lead determination 1 h, and 10, 20, and 30 days after lead administration. Animals were killed on day 32. Hypofunctional incisors from lead-treated rats erupted more slowly than control ones (P<0.05). These results show a previously unreported toxic effect of heavy metals.

A histological study of root-resected and root-transected rat incisors when eruption ceases, shortly before they are exfoliated from the socket.

Resection of the odontogenic region or root transection of normal (impeded) rat lower incisors showed that eruption ceased from 1 to 13 weeks when the base of the resected teeth (87.5%) or of the distal segment of the transected ones (86%) reached the alveolar-crest region. When the operated teeth reached the crestal region, the enamel-related periodontal tissues were absent and the periodontal ligament (PDL) was the only periodontal tissue that remained. The PDL of the crestal region may be considered as mature PDL, showing a length of approx. 5-6 6 mm at the mesial face of the tooth, 4-5 mm at lingual face and 1 mm at distal face; from these limits towards the apical end of the socket the PDL becomes gradually immature. The mature PDL seems not to have a role in the process of tooth eruption. Several factors can be suggested to explain the more frequent retention, at the crestal region of the socket, of impeded rather than unimpeded incisors submitted to the same procedures. The connective tissue that develops between the base of the tooth and the bone that fills the alveolus may have more time to organize itself in impeded than in unimpeded teeth, which erupt at a faster rate; this tissue could support and retain the impeded operated teeth longer than the unimpeded ones. The decrease in the mechanical properties of the PDL in the unimpeded condition may ease the traumatic effects and lead to exfoliation. Eruption might be stopped by the increase in occlusal forces, per unit area of root surface, as the root becomes shorter; this effect is likely to be greater in impeded than unimpeded teeth.

The effects of local trauma to the enamel-related periodontal tissues in the eruption of the rat incisor.

The periodontal tissues related to enamel (PTE) of the rat incisor comprise a connective tissue derived from the dental follicle and the enamel organ with its successive stages of development. Localized damage to these tissues in rat lower incisors was done surgically in three ways: with an endodontic file introduced into the labial periodontal space through either (i) its basal or (ii) its incisal extremities, or (iii) by the partial removal of the mandibular lower border, at the level of the molar teeth, together with the introduction of an endodontic file into the incisal part of that space. The lesions in the molar region of the PTE produced first a variable period of retarded eruption, and, depending upon their extent or degree were followed by a cessation of the eruptive movement and, in the majority of the operated teeth, a recovery of the normal eruption rate before the end of the experiment (17 weeks after surgery). Access to the PTE through the basal portion of the socket was erratic, but when the tissues were damaged produced similar effects. Effects on eruption of lesions produced through the alveolar crest were minimal or even absent. Localized injury to the periodontal ligament of either lower or upper incisors did not produce similar effects on tooth eruption. The dental follicle and the enamel organ of teeth of limited growth when their crown is completed are similar to the PTE in the molar region of continuously growing rodent incisors. In teeth of limited growth these tissues play an essential part in the intraosseous stage of eruption. The results here suggest that the PTE may also have a role in the supraosseous stage of eruption, which is continuous in teeth such as rat incisors due to the presence of a continuously functioning odontogenic organ.

The effect of vinblastine on the incorporation of [3H]-glycine into proteins of the periodontal ligament of impeded and unimpeded mouse incisors.

The effect of vinblastine on the protein metabolism of the periodontal ligament of impeded and unimpeded mouse incisors was studied by [3H]-glycine labelling and radioautography. The silver-grain concentration was determined in areas adjacent to the tooth, areas adjacent to bone and, as an internal control, in the dentine matrix. From 1 to 12 h there was no difference between treated and control animals; thus the drug did not alter protein biosynthesis. Later, the silver-grain concentration was significantly higher in areas adjacent to both bone and tooth in vinblastine-treated animals, suggesting a longer half-life of the labelled proteins. No significant differences between normal or unimpeded erupting incisors of both groups were detected. Dentine matrix showed a possibly higher re-utilization of the labelled amino acid in vinblastine-treated animals. The amount of labelled protein removed by collagenase was similar in both groups, while the concentration of grains due to collagenase-resistant proteins was significantly higher in treated animals, particularly at 96 h after the injection of labelled glycine. The relation between the increased amount of non-collagenous proteins in the periodontal ligament and the decrease in the rate of eruption caused by vinblastine was not established. However, among these proteins, fibronectin and proteoglycans are thought to be important factors in tooth eruption.

[Death from fluoro-silicate in floor polish].

A fatal case of poisoning due to ingestion of an apparently innocuous household product is described. A healthy 28-year-old man accidentally drank floor polish (Cristalizador, a Spanish import). On arrival at the emergency room a few hours later he passed large amounts of bloody stool and lost consciousness. A call to the Spanish Poison Center revealed that although not indicated on the label, the polish contained a highly poisonous salt, fluoro-silicate. Blood gas analysis revealed severe metabolic acidosis. Serum calcium was 3.8 mg/dL. The post-resuscitation ECG showed subendocardial ischemia and ST-elevation in the anteroseptal wall and prolonged QT-interval. In the intensive care unit he received large amounts of fluids, dopamine, sodium bicarbonate and calcium. Despite the treatment, his condition continued to deteriorate: VPB's appeared, there was a short run of ventricular tachycardia and then atrial fibrillation developed. Further treatment included lidocaine, verapamil, amiodarone, and electrical cardioversion. Blood pressure remained low and 11 hours after admission he died of myocardial infarction, severe arrhythmia and multi-organ failure.

The effect of Vinblastine on the incorporation of (3H)-glycine into proteins of the periodontal ligament of impeded and unimpeded mouse incisors / O efeito do Vinblastine na incorporação de (3H)-glycine nas proteinas do ligamento periodontal de impedidos e não impedidos em incisivos de ratos

The effect of vinblastine on the protein metabolism of the periodontal ligament of impeded and unimpeded mouse incisors was studied by (3H)-glycine labelling and radioautography. The silver-grain concentration was determined in areas adjacent to the tooth, areas adjacent to bone and, as an internal control, in the dentine matrix. From 1 to 12h there was no difference between treated and control animals; thus the drug did not alter protein biosynthesis. Later, the silver-grain concentration was significantly higher in areas adjacent to both bone and tooth in vinblastine-treated animals, suggesting a longer half-life of the labelled proteins. No significant differences between normal or unimpeded erupting incisors of both groups were detected. Dentine matrix showed a possibly higher re-utilization of the labelled amino acid in vinblastine-treated animals. The amount of labelled protein removed by collagenase was similar in both groups, while the concentration of grains due to collagenase-resistant proteins was significantly higher in treated animals, particularly at 96h after the injection of labelled glycine. The relation between the increased amount of non-collagenous proteins in the periodontal ligament and the decrease in the rate of eruption caused by vinblastine was not established. However, among these proteins, fibronectin and proteoglycans are thought to be important factors in tooth eruption

In vitro penetration of 125I-amelogenin into the enamel and enamel organ of rat incisors.

This work attempted to introduce pre-labelled intact amelogenins into developing rat enamel in vitro. The intention was ultimately to trace the fate of such proteins in the developing enamel matrix and to examine the effect of these and other molecules on ameloblast behavior. The penetration of 125I-amelogenin (25 KDa) directly into the young enamel of rat incisors, in vitro, keeping the enamel organ intact is described. The enamel (an extension approximately 8 mm from the apical end of the tooth) together with the enamel organ, was separated from the underlying dentine and placed over a strip of filter paper covering a well of micro-culture slide filled with Eagle's medium containing 125I labelled amelogenin and incubated at 37 degrees C. The enamel faced the strip of filter paper and so was adjacent to the medium. After 1 h pieces were either washed in cold medium, fixed and embedded in Epoxy-resin, or incubated in cold medium for another 1 to 10 h at 37 degrees C before embedding. One-micron thick sections were processed for autoradiography and the results showed a decreasing gradient of silver grain concentration from the dentino-enamel junction towards the enamel organ. It is expected that by determining the nature of the labelled material incorporated into the enamel and enamel organ the fate of amelogenins could be better understood.

[Histochemical detection of glycoproteins and glycosaminoglycans in the respiratory mucosa of albino rats during estrous cycle, pregnancy and puerperium]. / Detecção histoquímica de glicoproteínas e glicosaminoglicanos na mucosa respiratória de ratas albinas durante o ciclo estral, prenhez e puerpério.

In this work we attempted to detect, with histochemical methods, the possible modifications in the mucus of the respiratory mucosa of albino female rats during estral cycle, pregnancy and puerperium. Based on its results, it was possible to conclude that: a--There were no modifications in the nature of the epithelial and supraepithelial mucus during the studied periods: b--The Alcian Blue staining from lamina propria is absent during pregnancy and present during puerperium.

Thyroid function in hemidecorticate rats.

1. Thyroid function was evaluated in hemidecorticate (HD) and control (C) rats by determining serum T3 and T4 levels and the development of incisors and mandibles and through analysis of various histological features of the thyroid such as follicle size, colloid droplet content and [3H]-glycine uptake by follicular cells. 2. HD animals presented normal levels of circulating T3 but significantly lower T4 levels. 3. There was slight atrophy of the gland in HD animals and fewer colloid droplets were present in the cytoplasm of the follicular cells in this group, indicating a reduction in the breakdown of thyroglobulin. [3H]-glycine uptake by HD indicated that the rate of thyroglobulin biosynthesis was not altered in the experimental animals. 4. The growth of mandibles (weight) and incisors (weight and length) was reduced in HD compared to the control animals. 5. These results suggest that hemidecortication causes mild hypothyroidism (trophoprivic type) probably by affecting hypothalamic function.

The effects of cerebral hemidecortication on the eruption rate and uptake of [3H]-glycine by the periodontal ligament of the rat incisor.

Hemidecortication, which consists of removing one cerebral hemisphere, leaving intact the thalamus and hypothalamus, affects the hypothalamus-hypophyseal axis producing hypothyroidism. Hemidecorticate rats showed a significant decrease in the weekly eruption rate of the upper incisors and partial recovery after the administration of thyrotrophin-releasing hormone (TRH). The uptake of [3H]-glycine, 1 and 4 h after a single injection, shown by radioautography, was 25 to 50 per cent higher in the periodontal ligament of the experimental animals. Most of the labelled material was non-collagenous proteins because only 20 to 30 per cent was removed by collagenase.

Thyroid function in hemidecorticate rats

1. Throid function was evaluated in hemidecorticate (HD) and control (C) rats by determining serum T3 and T4 levels and the development of incisors and mandibles and through analysis of various histological features of the thyroid such as follicle size, colloid droplet content and [3H] - glycine uptake by follicular cells. 2. HD animals presented normal levels of circulating T3 but significantly lower T4 levels. 3. There was slight atrophy of the gland in HD animals and fewer colloid droplets were present in the cytoplasm of the follicular cells in this group, indicating a reduction in the breakdown of thyroglobulin. [3H] - glycine uptake by HD indicated that rate of thyroglobulin biosynthesis was not altered in the experimental animals. 4. the growth of mandibles (weight) and incisors (weight and lenght) was reduced in HD compared to the control animals. 5. These results suggest that hemidecortication causes mild hypothyroidism (trophoprivic type) probably by affecting hypothalamic function

The effects of cerebral hemidecortication on the eruption rate and uptake of [3H]-glycine by the periodontal ligament of the rat incisor / Efeito do hemidecorticação cerebral em relação a erupção e incorporação (3h) glicine no ligamento periodontal do incisivo de rato

Hemidecortication, which consists of removing one cerebral hemisphere, leaving intact the thalamus and hypothalamus, affects the hypothalamus-hypophyseal axis producing hypothyroidism. Hemidecorticate rats showed a significant decrease in the weekly eruption rate of the upper incisors and partial recovery after administration of thyrotrophin-releasing hormone (TRH). The uptake of [3H]-glycine, 1 and 4 h after a single injection, shown by radioautography, was 25 to 50 per cent higher in the periodontal ligament of the experimental animals. Most of the labelled material was noncollagenous proteins because only 20 to 30 per cent was removed by collagenase

Effect of vinblastine on the cell cycle and migration of ameloblasts of mouse incisors as shown by autoradiography using 3H-thymidine.

The effects of vinblastine on the cell cycle and the migration of ameloblasts were studied in the lower incisors of mice by labelling the cells with 3H-thymidine ([3H]TdR) and radioautography. A group of mice received 2 micrograms/g of body weight vinblastine intraperitoneally and 6 hr after these animals and those of a control group were injected with 1 microCi/g body weight of [3H]TdR, and sacrificed at time intervals from 0.75 hr to 15 days. The generation time of ameloblasts in the progenitor compartment was 14.8 hr in animals treated with vinblastine and 17 hr in the controls, using the FLM curve method; with the grain dilution method the duration was respectively 29.25 hr and 25.96 hr. The thymidine labelling index of the treated animals was 50% higher than the controls. The velocity of ameloblast migration, determined either by the displacement of the most incisally labelled cell or by the grain dilution method, was lower in the experimental group (2.48 cell positions/hr and 9.18 microns/hr respectively) as compared with the control (3.21 cell positions/hr and 18.88 microns/hr respectively). The results on the ameloblast production rate are contradictory but the slowing down in the velocity of cell migration is compatible with a decrease of the rate of cell production in the progenitor compartment as a vinblastine effect.

Catecholamines and congenital pain insensitivity.

The congenital pain insensitivity syndrome is accompanied by: a) the presence of a yellow-brown pigment in the basal layer of the epidermis with the histochemical properties of melanin, b) decrease of urinary and blood concentration of dopamine and norepinephrine, c) excretion of melanin and of an abnormal as yet unidentified phenolic metabolite, d) increase in urinary p-hydroxyphenyllactic acid, p-hydroxyphenylacetic acid, indole acetic acid, and e) a high homovanillic acid/vanillylmandelic acid (HVA/VMA) ratio. In this report we show that analgesic patients differ from controls by: a) an increase in norepinephrine excretion after L-tyrosine administration, and b) an increase in norepinephrine, dopamine, DOPA + DOPAC excretion after L-DOPA administration. The administration of L-DOPA eliminates the difference in HVA/VMA ratio between patients and controls. Serum and platelet monoamine oxidase, dopamine beta-hydroxylase and catechol-O-methyltransferase are normal and urinary excretion of biopterins, morphine-like compounds and endorphins is also within the normal range. The comparison of catecholamine metabolism in patients with phenylketonuria, Lesh-Nyham syndrome, congenital sensory neuropathy with anhydrosis and familial dysautonomia on the basis of our data and those in the literature suggests that patients with congenital pain insensitivity display abnormal catecholamine metabolism.