Initial Resorption Research Articles

Degradation and Bone-Contact Biocompatibility of Two Drillable Magnesium Phosphate Bone Cements in an In Vivo Rabbit Bone Defect Model.

The use of bone-cement-enforced osteosynthesis is a growing topic in trauma surgery. In this context, drillability is a desirable feature for cements that can improve fracture stability, which most of the available cement systems lack. Therefore, in this study, we evaluated a resorbable and drillable magnesium-phosphate (MgP)-based cement paste considering degradation behavior and biocompatibility in vivo. Two different magnesium-phosphate-based cement (MPC) pastes with different amounts of phytic acid (IP 6) as setting retarder (MPC 22.5 and MPC 25) were implanted in an orthotopic defect model of the lateral femoral condyle of New Zealand white rabbits for 6 weeks. After explantation, their resorption behavior and material characteristics were evaluated by means of X-ray diffraction (XRD), porosimetry measurement, histological staining, peripheral quantitative computed tomography (pQCT), cone-beam computed tomography (CBCT) and biomechanical load-to-failure tests. Both cement pastes displayed comparable results in mechanical strength and resorption kinetics. Bone-contact biocompatibility was excellent without any signs of inflammation. Initial resorption and bone remodeling could be observed. MPC pastes with IP 6 as setting retardant have the potential to be a valuable alternative in distinct fracture patterns. Drillability, promising resorption potential and high mechanical strength confirm their suitability for use in clinical routine.

Allogeneic Demineralized Dentin Matrix Graft for Guided Bone Regeneration in Dental Implants

Autogenous and allogeneic demineralized dentin matrices (Auto-DDM and Allo-DDM, respectively) are currently used for guided bone regeneration (GBR). Buccal marginal bone (BMB) resorption is critical for successful implant integration. This study analyzed BMB resorption around dental implants for GBR between the control group (Auto-DDM graft) and experimental group (Allo-DDM graft). From 2014 to 2019, we enrolled 96 patients (59 males, 37 females, average 57.13 years) who received GBR (52 and 44 using Allo-DDM and Auto-DDM, respectively,) without a barrier membrane and a simultaneous single dental implantation (54 in the maxilla and 42 in the mandible). BMB height was measured immediately after GBR, at prosthetic loading, and 12 months after loading. BMB resorption was classified as initial resorption (between GBR and prosthetic loading) and functional resorption (during 12 months after prosthetic loading). The differences in the BMB levels of Auto-DDM and Allo-DDM were analyzed between the initial and functional resorption stages by independent sample t-test. Auto-DDM and Allo-DDM showed similar BMB changes in initial resorption (0.73 ± 0.97 and 0.72 ± 0.77 mm, respectively) and functional resorption (0.69 ± 0.81 and 0.48 ± 0.58 mm, respectively) without a significant difference between the maxilla and mandible. For GBR, Allo-DDM is comparable to Auto-DDM in terms of BMB resorption.

Intrusive reawakening of El Chichón volcano prior to its Holocene eruptive hyperactivity

El Chichón volcano in southeastern Mexico (Chiapas) has produced compositionally homogeneous trachyandesite throughout its ca. 372 kyr eruptive history, but crystal-scale heterogeneity reveals a complex interplay between magmas generated and stored at different crustal levels. High-sensitivity ion microprobe 238U-230Th zircon dating from the last two eruptions of El Chichón (1982 and 550 BP) demonstrates that most zircon crystallized between 0 and ca. 40 ka. Few zircon crystals date back to ca. 130 kyr, and none to the Middle Pleistocene phase of eruptions. Trace elements and oxygen isotope variations in zircon indicate fairly stable conditions in the magma chamber between ca. 20 and 130 ka, with average Ti-in-zircon temperatures estimated at 712 °C and δ18O values of +6.6‰. However, excursions to high Ti-in-zircon temperatures and high δ18O values in zircon occurred at ca. 24 ka. These excursions also mark the onset of subsequent progressive changes to occasionally higher Ti-in-zircon temperatures, lower δ18O values, and more primitive magma compositions (e.g., high Eu/Eu*, Zr/Hf and Th/U). Systematic rim-ward decrease in δ18O is recorded by juvenile zircon domains which quasi-continuously crystallized for up to 30 kyr prior to eruption. Textural relationships and O-isotopic variations within single zircon crystals are thus evidence for magma recharge causing initial resorption of xenocrystic zircon, rapid zircon re-saturation driven by local supersaturation, and effective magma mixing with sediment-contaminated high-δ18O melts from a boundary layer at the contact of the magma reservoir to country rock. Initial thermal and compositional defrosting of an intermediate boundary layer and its crystal cargo may have been rapid due to the brief duration of high-temperature recharge events, as evidenced by the preservation of zircon xenocrysts. The delay of at least 12 kyr between major recharge episodes recorded by zircon and the onset of Holocene eruptions at brief recurrence intervals suggests that frequent eruptions only started when trachybasaltic magma recharge continued or intensified during the Holocene.

Coupling of Bone Resorption and Formation in Real Time: New Knowledge Gained From Human Haversian BMUs.

It is well known that bone remodeling starts with a resorption event and ends with bone formation. However, what happens in between and how resorption and formation are coupled remains mostly unknown. Remodeling is achieved by so-called basic multicellular units (BMUs), which are local teams of osteoclasts, osteoblasts, and reversal cells recently proven identical with osteoprogenitors. Their organization within a BMU cannot be appropriately analyzed in common histology. The originality of the present study is to capture the events ranging from initiation of resorption to onset of formation as a functional continuum. It was based on the position of specific cell markers in longitudinal sections of Haversian BMUs generating new canals through human long bones. It showed that initial resorption at the tip of the canal is followed by a period where newly recruited reversal/osteoprogenitor cells and osteoclasts alternate, thus revealing the existence of a mixed "reversal-resorption" phase. Three-dimensional reconstructions obtained from serial sections indicated that initial resorption is mainly involved in elongating the canal and the additional resorption events in widening it. Canal diameter measurements show that the latter contribute the most to overall resorption. Of note, the density of osteoprogenitors continuously grew along the "reversal/resorption" surface, reaching at least 39 cells/mm on initiation of bone formation. This value was independent of the length of the reversal/resorption surface. These observations strongly suggest that bone formation is initiated only above a threshold cell density, that the length of the reversal/resorption period depends on how fast osteoprogenitor recruitment reaches this threshold, and thus that the slower the rate of osteoprogenitor recruitment, the more bone is degraded. They lead to a model where the newly recognized reversal/resorption phase plays a central role in the mechanism linking osteoprogenitor recruitment and the resorption-formation switch. © 2017 American Society for Bone and Mineral Research.

Autogenous Bone Marrow Aspirate Coated Synthetic Hydroxyapatite for Reconstruction of Maxillo-Mandibular Osseous Defects: A Prospective Study.

This prospective study was conducted to evaluate the bone regeneration capacity of synthetic hydroxyapatite mixed with autogenous bone marrow aspirate when used as a bone graft substitute in maxillo-mandibular osseous defects. This study included nine patients with histopathalogically proven benign osteolytic lesions in maxilla and mandible that were treated with enucleation or marginal resection followed by bone marrow aspirate coated synthetic biphasic hydroxyapatite (hydroxyapatite and beta tricalcium phosphate) graft placement. Incorporation of graft was assessed based on Irwin's radiologic staging. The efficacy of graft to form new bone was radiologically evaluated by observing the sequential changes of density at grafted site using gray scale level histogram which was processed in adobe photoshop 7.0 elements. Clinical assessment of recipient and donor sites was done. Based on Irwin's radiologic staging, at 6month follow up period, obvious incorporation of graft with new bone was observed. Sequential changes in bone density measured by gray scale histogram revealed initial resorption followed by replacement of BMA coated hydroxyapatite with new bone formation. None of the patients eventually had complications like infection, wound dehiscence, graft loss at recipient sites at 6months follow up period. Autogenous bone marrow aspirate in combination with synthetic hydroxyapatite is an effective option for accelerating bone regeneration in small to moderate sized jaw bone defects. This mixture provides all the three critical elements needed for bone regeneration (osteogenesis, osteoinduction and osteoconduction) with an added advantage of obviating donor site morbidity.

Congenital Chylothorax: Diagnosis Problems

ABSTRACT Fetal pleural effusion is most frequently a marker of chylothorax. It is usually unilateral and frequently located on the right side, due to the anatomical position of the thoracic duct. Fetal hydrothorax can be either primary or secondary to chromosomal, cardiovascular, hematologic, liver or metabolic diseases, congenital infections and skeletal dysplasia, or placenta or cord abnormalities. Congenital chylothorax in the newborn can be associated with symptoms of severe respiratory distress, requiring rapid evacuation and respiratory support. In chylothorax, the appearance of the fluid is milky, yellowish, with a high cell count and increased level of triglycerides. The treatment of neonatal chylothorax involves removal of substantial effusion, pleural drainage and initiation of a special diet to limit chylothorax fluid restoration. This paper presents the case of a premature newborn at a gestational age of 36 weeks, with fetal hydrothorax, which was diagnosed in utero at 28 weeks of pregnancy. After the initial resorption of the pleural effusion, it restored in parallel with the increasing quantity of ingested breast milk. How to cite this article Mátyás M, Blaga L, Hăşmăşanu M, Zaharie G. Congenital Chylothorax: Diagnosis Problems. Donald School J Ultrasound Obstet Gynecol 2014;8(2):218-221.

Development of Labrus Bergylta (Ascanius 1767) Larvae from Hatching to Metamorphosis

Ballan wrasse, Labrus bergylta (Ascanius, 1767), has commercial interest as a cleaner fish in aquaculture, and culture of juveniles may be a good alternative to catching wild fish. However, basic knowledge of early development is limited. To study hatching and larvae ontogenesis, eggs were collected from a broodstock of wild caught ballan wrasse held in captivity. Larvae were fed rotifers for 27 days; Artemia was introduced at day 20 and fed larvae to day 49 after hatching. Age at hatching, and larval ontogenesis based on external morphological features were linked to the chronological age of larvae as days post hatching (DPH) and physiological age as degree day (°C.day) and standard length (SL). The ballan wrasse egg diameter was 1.05 ± 0.04 mm and 0.87 ± 0.05 mm with and without the gelatinous layer, respectively, and hatched at a SL of 3.64 ± 0.05 mm, 7 days, i.e., 72°C.day, after fertilization. The ontogeny of larvae from hatching to metamorphosis was divided into four stages. Yolk sac larva, 0 to 9 DPH (SL 4.28 ± 0.11 mm), where mouth opens and pigmentation of the eyes is seen. Dilated swim bladder is visible. Preflexion larva, 10 to 25 DPH (SL 5.35 ± 0.30 mm); yolk sac has disappeared, and initial formation of caudal fin rays occurs. Gaseous inflation of swim bladder is observed. Flexion larva, 26 to 33 DPH (SL 5.9 ± 0.78 mm), initial resorption of primordial fin fold is seen. Postflexion larva, 34 to 49 DPH (SL 10.52 ± 0.82 mm) by the end of this stage (age 686°C.day), the dorsal, anal, caudal and pelvic fins were developed. The ontogenetic development, linked to SL, chronological and physiological age, provides a baseline reference and makes it possible to compare developmental levels in future studies of ballan wrasse in culture and wild populations.

Breast Enhancement with Macrolene

Sir:FigureWe had the great pleasure of reading the extremely interesting article by Hedén et al.1 entitled “Macrolene for Breast Enhancement: 12-Month Follow-Up.” We congratulate the authors for the accurate description of their experience concerning the use of a cross-linked stabilized hyaluronic acid–based gel of nonanimal origin, used as a biodegradable filler material for breast enhancement in 24 women. We would like to take the opportunity to further discuss indications, advantages, and disadvantages of this recent procedure. Injection of any material in a healthy breast, including fat2,3 and biodegradable fillers, always arouses some fear and doubt. The authors claim that nonanimal stabilized hyaluronic acid–based gel can be considered an alternative to silicone or saline implants, like fat grafting. Compared with autologous fat transfer, the Macrolene injection can be performed under local anesthesia and in less time but, in our opinion, is burdened by a high incidence of complications, even if most of them can be resolved quickly. We think that the incidence of adverse events reported in the 24 patients enrolled in the study is high. Indeed, 69 percent of patients experienced such complications as capsular contracture, breast tenderness, visibility, and displacement of the filler. While pointing out some disadvantages, surely we should list the possibility of the development of capsular contracture and filler migration. This obviously does not occur in lipofilling and, if the patient wishes to undergo a breast augmentation with implants, removal of this material is recommended and desirable. A requirement for Macrolene injection is patients with a pinch test greater than 2 cm; considering that these are usually patients with small breasts, not all are ideal candidates, thus increasing the risk of visibility, whereas to perform fat grafting it is necessary only that patients have adipose tissue. Furthermore, fat transferred into the breast, after initial resorption, remains constant, unlike Macrolene, which is gradually reabsorbed. Another deterrent might be the hypothetical high cost of this material, if we consider that it would take an average of 100 cc per breast, and Macrolene VRF 30 is supplied in 10-ml syringes. The authors did not mention whether this material interferes with breast imaging. In this respect, the authors performed magnetic resonance imaging only to control the right plane of injection and the rate of resorption for 1 year, but no mention was made regarding any modification of the breast parenchyma or difficulties in detection of eventual malignancies. Veber et al.4 recently published in this Journal an exhaustive study on radiographic findings after breast enhancement with autologous fat grafting. They reported that fat transfer to native breast does not hamper breast imaging and follow-up. Similar study are therefore desirable for Macrolene injections. In our opinion, we think that, as is the case with lipoaugmentation,5 there must be a proper informed consent for patients willing to undergo the procedure, and that all feasible adverse reactions should be explained. Finally, we believe that controlled clinical trials are needed to evaluate the safety and efficacy of Macrolene for breast enhancement, especially regarding breast imaging, and we need to proceed with caution, just as is the case with fat injection. Stefano Bonomi, M.D. Fernanda Settembrini, M.D. André Salval, M.D. Department of Plastic Reconstructive Surgery and Burn Unit Center, Ospedale Niguarda Ca' Granda, Milan, Italy DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication.

Ossicular Bone Modeling in Acute Otitis Media

A number of middle ear diseases are associated with pathologic bone modeling, either formative or resorptive. As such, the pathogenesis of a sclerotic mastoid has been controversial for decades. Experimental studies on acute middle ear infection have shown progressive osteoneogenesis in the bone structures surrounding the middle ear cavity, and a few studies have reported acute changes of the ossicular chain. However, detailed qualitative and quantitative information on ossicular bone modeling dynamics has not been accounted for and is thus the purpose of this study. The histopathology of the middle ear bone tissue structures was studied longitudinally in a rat model of acute pneumococcal otitis media, from Days 1 to 28 postinoculation. Resorptive and formative activity was semiquantitated for the ossicles and the bone tissue structures surrounding the middle ear cavity. Qualitative and semiquantitative histopathology revealed initial osteoresorption, followed by increasing apposition of new bone in the middle ear cavity. Equivalently, the ossicular chain and joints were subject to initial resorption and subsequent new bone formation, but the changes occurred were delayed and to a far lesser extent. A single incident of acute otitis media changes the osseous structures of the middle ear, which may alter properties of ossicular chain conduction. Modeling of ossicular bone is postponed compared with the bone tissue surrounding the middle ear cavity, and to a much lesser extent. The differentiated modeling pattern suggests that ossicular bone tissue possesses biologic properties resistant to morphologic changes.

Severe root resorption in orthodontic patients treated with the edgewise method: Prevalence and predictive factors

Our aims in this study were to assess the prevalence of severe root resorption and identify possible associations in orthodontic patients treated with the edgewise method. The sample included 1049 patients who had periapical radiographs taken for all incisors before and after treatment. The radiographs were examined by 2 orthodontists using an x-ray viewer with standard light intensity. These variables were collected: root shape, overbite, initial resorption, and hypodontia. The patients were classified according to sex, Angle classification, ethnicity, age, duration of treatment, type of dentition (mixed or permanent), and treatment with or without extraction of 4 premolars. Resorption was considered severe when it affected more than a third of the length of the root. Statistical analysis included the chi-square test and both simple and multiple logistic regression (P < or =0.05). Severe root resorption was observed in 14.5% of the sample. Patients treated with exodontia of the first premolars (odds ratio [95% CI] = 6.38 [4.2-9.7]), those who had triangle-shaped roots at the beginning of treatment (odds ratio [95% CI] = 4.67 [3.1-6.9]), and those with initial root resorption (odds ratio [95% CI] = 4.52 [2.7-7.6]) had a greater chance of developing severe root resorption during orthodontic treatment. A high prevalence of severe root resorption was observed in Brazilian patients treated with the edgewise method. The main factors directly involved in severe resorption were extraction of first premolars, triangle-shaped roots, and root resorption before treatment.

A prospective randomized split‐mouth study comparing iliac onlay grafts in atrophied edentulous patients: covered with periosteum or a bioresorbable membrane

In this prospective study, solid monocortical iliac onlay grafts of the maxilla were randomly covered with a bioresorbable membrane and periosteum within the maxilla. Histologic specimens were analyzed by light microscopy after a healing period of three months and the rate of resorption of the grafts were measured. Fourteen patients (9 females and 5 males), with a mean age of 56 years (range 25-72) underwent augmentation with avascular iliac onlay bone grafts. The grafts were randomly covered either with a bioresorbable membrane (MC) or periosteum (PC). Resorption was measured with a digital caliper at the microscrews (slashed circle 1.5 mm) used to fixate the graft. Histologic evaluation of the specimens derived from the graft with a trephine bur (slashed circle 2 mm) from the implant site at implant placement after a 3-month healing period. Statistical evaluation of the data was performed using Analysis of variance and the Wilcoxon signed rank test. Clinical appearance of the augmented bone after 3 months showed a dense cortical layer with good vascular perfusion. Thirty-three sites in 13 patients (one dropped put) were analyzed histomorphometrically and showed an average of 46% newly formed bone with no significant difference between the groups (P=0.46). The mean resorption rate at 56 measured sites was 1.2 mm (range 0.3-3.4 mm) after 3 months, with no significant difference between the MC sites and the PC sites (P=0.38). Histomorphometry of new bone formation after 3 months demonstrates no significant difference between the PC and MC groups. Initialization of graft resorption can be seen after 3 months with no significant difference as to whether the graft was covered with a membrane or the periosteum. This study provides evidence that after avascular iliac bone grafting, the revascularization of the graft was sufficient after 3 months regardless of the graft coverage with no effect on the amount of initial resorption of the graft.

The effect of prophylactic treatment with risedronate on stress fracture incidence among infantry recruits

When subjected to strains or strain rates higher than usual, the bone remodels to repair microdamage and to strengthen itself. During the initial resorption phase of remodeling, the bone is transitorily weakened and microdamage can accumulate leading to stress fracture. To determine whether short-term suppression of bone turnover using bisphosphonates can prevent the initial loss of bone during the remodeling response to high bone strain and strain rates and potentially prevent stress fracture, we conducted a randomized, double-blind, placebo-controlled trial of 324 new infantry recruits known to be at high risk for stress fracture. Recruits were given a loading dose of 30 mg of risedronate or placebo daily for 10 doses during the first 2 weeks of basic training and then a once a week maintenance dose for the following 12 weeks. Recruits were monitored by biweekly orthopedic examinations during 15 weeks of basic training for stress fractures. Bone scans for suspected tibial and femoral stress fractures and radiographs for suspected metatarsal stress fractures were used to verify stress fracture occurrence. By the intention-to-treat analysis and per-protocol analysis, there was no statistically significant difference in the tibial, femoral, metatarsal, or total stress fracture incidence between the treatment group and the placebo. We conclude that prophylactic treatment with risedronate in a training population at high risk for stress fracture using a maintenance dosage for the treatment of osteoporosis does not lower stress fracture risk.

Influence of polymeric additives on the biological properties of brushite cements: an experimental study in rabbit.

The resorbability and ability of calcium phosphate hydraulic cements to promote new bone formation was investigated in vivo. The effects of two hydrosoluble polymeric additives (hyaluronic acid, and xanthan gum,) on the biological response of two brushite cement formulations (BHC-A vs BHC-B) was investigated. The brushite cements differed in P/Ca (0.71 vs 0.98) and S/Ca (0.10 vs 0.005) atomic ratios and by the presence of calcium sulfate hemihydrate in BHC-A. Polymer-free cements were used as controls. Cement specimens were injected in cylindrical bone defects manually drilled in the distal condyle of rabbit femora. The implants were harvested at 12 and 24 weeks after implantation and subjected to quantitative histomorphometry. The study showed a significantly lower resorption rate for cement BHC-A, which induces the formation of well-mineralized bone in close apposition to the residual material. In contrast, cement BHC-B showed a significant increase of bone formation period and the formation of a thick layer of unmineralized osteoid tissue at the bone/residual cement interface. The presence of xanthan gum made the biological response even worse, particularly in the case of cement BHC-B. The presence of hyaluronic acid has little effect, except for a slight decrease in initial resorption rate, in the case of cement BHC-A.

A resorbable porous ceramic composite bone graft substitute in a rabbit metaphyseal defect model

The success of converted corals as a bone graft substitute relies on a complex sequence of events of vascular ingrowth, differentiation of osteoprogenitor cells, bone remodeling and graft resorption occurring together with host bone ingrowth into and onto the porous coralline microstructure or voids left behind during resorption. This study examined the resorption rates and bone infiltration into a family of resorbable porous ceramic placed bilaterally in critical sized defects in the tibial metaphyseal–diaphyseal of rabbits. The ceramics are made resorbable by partially converting the calcium carbonate of corals to form a hydroxyapatite (HA) layer on all surfaces. Attempts have been made to control the resorption rate of the implant by varying the HA thickness. New bone was observed at the periosteal and endosteal cortices, which flowed into the centre of the defect supporting the osteoconductive nature of partially converted corals. The combination of an HA layer and calcium carbonate core provides a composite bone graft substitute for new tissue integration. The HA–calcium carbonate composite demonstrated an initial resorption of the inner calcium carbonate phase but the overall implant resorption and bone ingrowth behaviour did not differ with HA thickness.

Stochastically simulated assessment of anabolic treatment following varying degrees of cancellous bone resorption

The aim of this study was to investigate the recovery in cancellous bone stiffness resulting from anabolic treatment following varying degrees of resorption, using a stochastic simulation applied to a simplistic structure consisting of five vertical and five horizontal trabeculae. The structure was initially resorbed, and “bone” elements were stochastically removed until nominal resorptions of 10%, 15%, 20%, 25%, and 30% were achieved. A stochastic simulation of anabolic treatment was then applied where bone elements were added, continuing until the original stiffness had been regained, for example, simulating treatment of a patient with an anabolic agent after a period of postmenopausal resorption. The resorption and anabolic simulations were repeated three times for each of the nominal resorptions. The stiffness of the bone structure decreased linearly with resorption, with a slope of approximately −2 and an R 2 of 97.0%; hence, the stiffness fell at approximately twice the rate of the reduction in density. When the various structures regained their original density, the resultant stiffness also had a linear relationship with the original resorption, with a slope of −1 and a lower R 2 of 86.1%. This implies that the reduction in stiffness, when original density was regained, fell proportionately with the degree of initial resorption and, therefore, after a resorption of 30%, when original density was regained, the stiffness of the resultant structure was approximately 30% less than that of the original structure. The density required for the original stiffness to be regained increased linearly with the degree of initial resorption, with a slope of approximately 0.5 and an R 2 of 65.2%, lower than that observed for the previous relationships. This indicates a greater spread of data and suggests greater variability in the formation phase beyond the point of regained original density. Because irreversible connectivity reduction is widely considered to be one of the earliest manifestations of estrogen loss, these findings, although obtained on a simulation of a simplistic cancellous bone structure, support the concept of early intervention to prevent potentially irreversible deterioration of trabecular architecture after menopause.

Adaptive Bone Modeling and Remodeling in Acute Otitis Media Caused by Non-typeable or Type B Haemophilus influenzae or Moraxella catarrhalis

Experimental studies have shown that acute otitis media caused by Streptococcus pneumoniae alters modeling dynamics in bone tissue structures surrounding the middle ear cavity. Initial resorption of bone is followed by formative activity, seen as massive osteoneogenesis. However, neither resorptive nor formative activity occurs in the otic capsule, supporting the existence of a perilymphatic zone of specialized bone. This study investigates adaptive bone modeling in acute otitis media caused by other bacteria frequently encountered in this disease. Seventy-five rats were inoculated with either non-typeable or type b Haemophilus influenzae, or Moraxella catarrhalis (25 rats in each group). Five rats from each group were sacrificed on days 4, 8, 16, 60 and 180 post-inoculation. Qualitative as well as quantitative histopathology revealed increasing apposition of new bone on both sides of the original bony wall of the middle ear bulla, i.e. at the inner and outer periosteum. Remodeling activity was seen on later days of sacrifice, as typical osteone (Haversian system) formation. Measured bone thickness in four anatomically well-defined localities progressed to a peak 2 months post-inoculation, followed by some degree of normalization. However, bone thickness was still massively increased 6 months after the acute incident. Except in the otic capsule, resorptive and formative activity was found in all bone tissue structures surrounding the middle ear cavity. These findings were irrespective of the type of inoculated bacteria. However, non-typeable or type b Haemophilus influenzae induces significantly more new bone formation than Moraxella catarrhalis. We conclude that acute otitis media caused by either of the bacteria is accompanied by massive and progressive net osteoneogenesis, already evident on day 4 and peaking 2 months post-inoculation, followed by some degree of normalization. Non-typeable and type b Haemophilus influenzae induce more new bone formation than Moraxella catarrhalis, whereas other features of bone histomorphology were equivalent. The present findings further support the existence of a perilymphatic zone of specialized bone.

Penicillin Reduces New Bone Formation in Acute Otitis Media

Previous studies have shown that acute otitis media alters modeling dynamics in bone tissue structures surrounding the middle ear cavity. Initial resorption is followed by formative activity, which is seen as massive osteoneogenesis. However, neither resorptive nor formative activity occurs in the otic capsule, supporting the theory on existence of a perilymphatic barrier of specialized bone. To investigate the effect of penicillin administration on the pathological bone modeling in acute otitis media, we employed a rat model of acute pneumococcal otitis media. Five rats were sacrificed on postinoculation days 4, 8, 16, 90, and 180, preceded by oral administration of penicillin V 100 mg/kg per day, initiated on day 2 and lasting 5 (2) days. Using a light microscope, bone histomorphology was registered and the thickness measured in four well-defined localities, followed by comparison with a previous study of untreated animals. Measured bone thickness was unaffected by treatment on day 4, but significantly reduced in two localities on day 8 and in all localities on following days of sacrifice. Bone cytomorphology and histomorphology were otherwise unaffected by penicillin administration. Penicillin reduces new bone formation in acute otitis media, leaving other features of histomorphology unchanged.

Effect of Fosamax on Remodeling of the Bone Tissue and Bone Mass in Postmenopausal and Senile Osteoporosis

In 11 patients with postmenopausal and senile osteoporosis and decreased remodeling the effect of Fosamax on the bone tissue mass in different segments of skeleton was studied. Course of treatment was 12 months. Fosamax 10 mg/daily was found to provide marked analgesic effect to improve clinical course of disease during the first 6 months of treatment. Using dual-energy-x-ray absorptiometry the increase of bone tissue mass was detected in all examined skeleton segments (by 3.7-8.5%) of patients with initial low resorption (low oxyprolinuria and calcinuria). It mainly testified the stimulate effect of Fosamax on the process of bone formation. Increase of bone mass in femur neck confirmed that Fosamax unlike other medicines influenced not only the trabecular bone but the cortical one as well.

Implante de peritônio homólogo conservado após ceratectomia lamelar em cães

Estudou-se a viabilidade do uso do peritônio homólogo, conservado em glicerina, na reparação de lesões superficiais da córnea, após ceratectomia lamelar. Para tanto foram utilizados 7 cães, machos e fêmeas, pesando 10 kg em média. Realizou-se ceratectomia lamelar de 0,4 x 0,5 mm de lado e 1/3 da espessura da córnea, bilateralmente, e nomesmo período anestésico, seguida de implante de peritônio homólogo e utilizando-se sutura interrompida aplicada em toda a extensão do enxerto. Os animais foram sacrificados e seus globos oculares enucleados, em intervalos de 24 horas, 7, 15, 30 e 60 dias de pós-operatório. Para observação dos resultados, procedeu-se às avaliações clínica e histológica. Blefarospasmo, quemose e opacidade de córnea foram sinais comuns aos períodos precoces de pósoperatório,os quais foram desaparecendo até o 32a dia, quando o enxerto se encontrava em plena fase de desopacificação e o globo ocular isento de sinais de inflamação. Epitelização total do enxerto se fez presente aossete dias, seguida por reabsorção do mesmo, com ausência de infiltrado inflamatório aos 17 dias. Houve deposição de pigmento no estroma nos períodos tardros de avaliação. Não foi observado infiltrado inflamatório nem reação clínica que pudesse ser patognomônica de eliminação do enxerto. Diante das observações factuais de cada um dos tempos, admite-se o emprego do peritônio homólogo na reparação lamelar de lesões superficiais da córnea, constituindo-se, portanto, em mais uma opção de técnica de ceratoplastia no cão.

Bone and cartilage resorption in relation to tooth development in the anterior part of the mandible in cichlid fish: a light and TEM study.

This paper presents ultrastructural features of the contact region between particular tooth germs and Meckel's cartilage prior to, during, and after initial resorption of the perichondral bone and of the cartilage in the cichlids Hemichromis bimaculatus and Astatotilapia burtoni. Imminent resorption opposite such teeth is announced by the presence, in this region, of a particular cell type, considered to be a stage in the cytodifferentiation of osteoclasts. Slightly later, an osteoclast with typical ruffled border is seen to open a fenestra in the perichondral bone which surrounds Meckel's cartilage. Although the action of the osteoclast is directed primarily towards the bone, it may also affect, to a much lesser extent, the underlying uncalcified cartilage. Typically, fibroblast-like cells invade the resorption cavity along with the osteoclast; the tooth germ soon follows. Capillaries are seen to invade the cartilage only at a later stage when a large cavity has been established. It is proposed that the fibroblast-like cells may have a dual function: degradation of cartilage and deposition of new bone. Although these processes are normally limited to the area surrounding tooth germs at specific loci, tooth germs in other positions may sometimes be seen invade the cartilage. They do so either passively, because of the existence of such a cavity, or as a result of their own resorption-inducing activity. Whatever the mechanism, attachment bone is being deposited within the erosion cavity and on the surface of the exposed perichondral bone. The stimuli possibly eliciting resorption of Meckel's cartilage are discussed. It is hypothesized that pressure exerted by the growing tooth germ may stimulate the osteoblasts covering the bone surface and, in this way, provoke osteoclastic bone resorption.