Genetic Susceptibility to Fungal Infections

Reports of fungal infections have increased over the past decades, making them a major threat to human health. In this study, we review the effects of genetic defects on susceptibility to fungal diseases. To identify all relevant literature, we searched Google Scholar, PubMed, and Scopus and profiled studies published between 2008 and 2021. The results of several studies conducted on this subject have shown the significant effects of genetic variations such as hyper-IgE syndrome, Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome, dectin-1 deficiency, CARD9 mutations, STAT1 mutations, and IL17 mutationson the host immune system's response, which has an important impact on susceptibility to fungal infections. The underlying immune system-related genetic profile affects the susceptibility of individuals to different fungal infections; therefore, this subject should be further studied for better treatment of fungal diseases.

Antidiabetic, hypolipidemic, and antioxidant activities of Pistacia atlantica: A systematic review and meta-analysis of preclinical studies

To determine the pharmaceutical applications, we assessed the evidence from preclinical studies about the hypoglycemic, hypolipidemic, and antioxidant potential of Pistacia atlantica (PA) as a natural source for prevention and treatment of diabetes. A comprehensive literature search of the articles published until March 12, 2022 was conducted on PubMed, Embase, Web of Sciences, and Scopus databases, using relevant keywords. This meta-analysis included 12 articles that examined the blood glucose (BG), insulin, homeostatic model assessment for insulin resistance (HOMA-IR), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), malondialdehyde (MDA) and superoxide dismutase (SOD). A random-effects model was used to estimate the pooled effect size. Findings indicated that PA supplementation significantly decreased BG, HOMA-IR, TC, TG, and MDA, and increased insulin and SOD in diabetic animals compared with control group (p < .05). However, PA supplementation had no significant effects on HDL-C (p > .05). The subgroup analysis also confirmed the beneficial effect of PA supplementation with longer duration (>4 weeks) and higher doses (≥100 mg/kg/day) as well as in the extract type. The studies have heterogeneity associated with methodological diversity and there were some concerns about the risk of bias, especially about randomization and blind outcome assessment. This meta-analysis provided convincing evidence for antidiabetic, hypolipidemic, and antioxidant activity of PA in animals. Further high-quality studies are needed to firmly establish the clinical efficacy of the plant.

Protective Effects of Cinnamic Acid Against Hyperglycemia Induced Oxidative Stress and Inflammation in HepG2 Cells

Background

Cinnamic acid, a phenylpropanoid acid, has been investigated as a potential alternative therapy for diabetes and its complications in some studies.

Methods

In the first stage, the viability of HepG2 cells at different concentrations of glucose and CA was assessed by MTT assay. Oxidative stress markers) CAT, GPx, GSH, and MDA) were measured spectrophotometrically. After RNA extraction, the effect of different concentrations of CA on the expression of DPP4 and inflammatory factors (IL-6, NF- κB) in HepG2 cells was assessed using real-time PCR.

Results

In HepG2 cells, CA increased catalase and glutathione peroxidase activity and GSH production in a dose-dependent manner in the presence of high glucose concentrations, with the greatest effect seen at a concentration of 75 mg/ml. Also, it reduced the amount of MDA in high-glucose HepG2 cells. Furthermore, CA decreased the expression of DPP4, NF- κB, and IL-6 genes in HepG2 cells in the presence of high glucose levels.

Conclusions

The results of our study indicated that CA reduced hyperglycemia-induced complications in HepG2 cells by decreasing inflammatory gene expression, including IL-6 and NF- κB and inhibiting the expression of DPP4, and limiting oxidative stress.

A fuzzy rough copula Bayesian network model for solving complex hospital service quality assessment

Healthcare tends to be one of the most complicated sectors, and hospitals exist at the core of healthcare activities. One of the most significant elements in hospitals is service quality level. Moreover, the dependency between factors, dynamic features, as well as objective and subjective uncertainties involved endure challenges to modern decision-making problems. Thus, in this paper, a decision-making approach is developed for hospital service quality assessment, using a Bayesian copula network based on a fuzzy rough set within neighborhood operators as a basis of that to deal with dynamic features as well as objective uncertainties. In the copula Bayesian network model, the Bayesian Network is utilized to illustrate the interrelationships between different factors graphically, while Copula is engaged in obtaining the joint probability distribution. Fuzzy rough set theory within neighborhood operators is employed for the subjective treatment of evidence from decision makers. The efficiency and practicality of the designed method are validated by an analysis of real hospital service quality in Iran. A novel framework for ranking a group of alternatives with consideration of different criteria is proposed by the combination of the Copula Bayesian Network and the extended fuzzy rough set technique. The subjective uncertainty of decision makers' opinions is dealt with in a novel extension of fuzzy Rough set theory. The results highlighted that the proposed method has merits in reducing uncertainty and assessing the dependency between factors of complicated decision-making problems.

Assessment of cell phone effect on dental socket healing in rat

BACKGROUND

Electromagnetic waves can cause biological effects on repair process. Due to the proximity of the jaw bone and the soft tissue around it in a part of the face with which it has the closest contact during the cell phone use, this study aims to investigate the effect of mobile waves on socket healing after tooth extraction in rats.

MATERIAL

This experimental study was conducted on 32 rats. The case group was exposed to a 900 MHz frequency electromagnetic field for 30 min/d. Sacrificed eight rats from the case group and 7 rats from the control group on day 14, and 8 rats from the case group and 7 rats from the control group were sacrificed on day 28 at the end of the radiation period and CBCT and microscopic examinations on the maxillary bones and soft tissue were performed.

RESULTS

According to the findings, the healing process was significantly different in two groups in terms of the percentage of new bone formation on day 14 after the end of radiation (p = 0.014). The other measured parameters including the degree of inflammation, thickness of the formed bone, number of osteoblasts and Gray scale had no significant difference between the two groups in any of the 14-day and 28-day intervals.

CONCLUSIONS

The results of this study showed that intermittent exposure to high frequency electromagnetic fields over a period of 20 hours has no significant effect on the healing process of alveolar socket after tooth extraction in rats.

Probabilistic Risk Analysis of Process Systems Considering Epistemic and Aleatory Uncertainties: A Comparison Study

The fault tree analysis (FTA) is one of the important probabilistic risk assessment tools that is extensively used in different industrial applications. However, the classical FTA has been widely criticized due to its ambiguity and vagueness in finding the probability of basic events (BEs), and accordingly, in computing the probability of top events (TEs). In this paper, we propose a new approach considering the integration of fuzzy set theory and evidence theory for handling both types of uncertainties, i.e., epistemic and aleatory. In addition, to estimate the probability of TEs alternatively, the normal distribution is applied. By performing a numerical example of risk assessment in a collapse case study for a common offshore facility platform, the effectiveness of the approach is demonstrated. Finally, in this study, the sensitivity analysis is also performed to represent the vulnerability of the causes and the interaction of different inputs, meaning that the proposed model is highly reliable and effective for real applications.

Generalized Kerker's conditions under normal and oblique incidence using the polarizability tensors of nanoparticles

The polarizability tensors of a particle are its characteristic parameters, which once obtained, can be applied as equivalent representations of the particle in any problems involving plane wave illuminations. In this paper, the generalized Kerker's conditions for unidirectional scattering are derived, in the case of normal and oblique incidence, in terms of the polarizability tensors of any arbitrary nanostructures in homogeneous media and located on dielectric substrates. In order to present structures that corroborate the conditions derived from such polarizabilities, first, the effect of constituent material on the frequency response of the nanoparticle is investigated. Then, the dimensions of nanostructures that satisfy the first and second Kerker's conditions are evaluated, while it is also ascertained that by varying the excitation wavelengths in an individual nanoparticle, switching between forward and backward unidirectional scattering can be achieved. This creates numerous attractive possibilities for the manipulation of optical pressure forces. Moreover, the influence of impinging direction upon the forward-to-backward scattering ratio is studied. Since, in many applications, nanoparticles are situated on dielectric substrates to make the structures more practically feasible, in this work, the effect of substrates on the Kerker's conditions are evaluated. It is shown that the presence of a substrate adds new dimensions of polarizability to the structure. Despite this new polarizability, two structures are engineered, here, which create strong asymmetrical scattering over a wide frequency range and wide angle of incidence.

Analysis of substrated periodic metasurfaces under normal incidence

The analysis and synthesis of metasurfaces are important because of their emerging applications in a broad range of the operational wavelengths from microwaves to the visible light spectrum. Moreover, in many applications, like optical nanoantennas, absorbers, solar cells, and sensing, the presence of a substrate is apparent. Therefore, understanding the effects of substrates upon the metasurfaces is important, as the substrates typically affect the resonance behaviors of particles, as well as the interactions between them. In order to consider the impacts of substrates, this paper develops a method for the characterization and homogenization of substrated metasurfaces. This approach is based on independent studies of the electromagnetic behavior of the constituting nanoparticles, and the interactions between them. It uses image theory to calculate the interaction constant tensors in the presence of a dielectric substrate. Then, the contributions of the quasi-static interaction fields of the primary and image dipoles are considered as a homogeneous sheet of surface polarization currents. Finally, the closed-form expressions for the interaction constant tensors are derived. To show the accuracy of our proposed approach, the numerical results of the method are compared to other approaches, as well as with those generated by a commercial EM solver, which are all found to be in good agreement. Moreover, the effects of the refractive index of the substrate, the geometric characteristics of the particle, and periodicity of the array are also investigated on the interaction constants. We believe that this methodology is general and useful in the design and analysis of substrated metasurfaces for various applications.

Emerging Involvement of long non-coding RNAs in gastrointestinal associated inflammatory disorders

Gastrointestinal (GI) disorders including a wide range of infectious, inflammatory, autoimmune, etc. disorders. Inflammatory bowel and celiac disease are non-fatal but overwhelming GI associated disorders. IBD and celiac's complications, besides the great suffering, disturb the normal life of the patients and make them involved in mental and physical problems. The emerging role of genetic content is deniable for GI inflammatory disorders incidence, and long non-coding RNAs (lncRNAs) function is the recent topic for its association. Analyzing of absolute lncRNAs interference in GI inflammatory appearance remains in infancy, and more studies are requested. Here, we concisely performed a systematic review in the last knowledge up to 2020 to identify all of the significant lncRNAs associated with the initiation and progression of GI inflammatory diseases. Accordingly, this assay attempted to refer to the expression of lncRNAs changing from the normal state, discovery of genetic mechanisms, and main effectors that would trigger associated IBD and celiac expression and immune responses would be effective for therapeutic approaches. It could be useful for prognostic and diagnostic purposes of GI associated inflammatory disorders.

Oxidative stress induced by cadmium in lettuce (Lactuca sativa Linn.): Oxidative stress indicators and prediction of their genes

Environmental contamination with heavy metals is of concern as plants have the ability to absorb chemical toxicants facilitating the entry of toxic metals into the food chain. Lettuce (Lactuca sativa Linn.) was cultured in four nutrient solutions containing different concentrations of cadmium (0, 3, 6, and 9 mmol). The impact of heavy metal on the morphological features, antioxidant properties and antioxidant enzymes activity were investigated with primary focus on superoxide dismutase, ascorbate peroxidase, peroxidase and catalase enzymes. In silico methods were utilized in the study of the genes of these enzymes. Significant changes were observed in the morphological features of the plant with plants appearing stunted, more spherical and yellow in colour. A decrease in the dry mass of the plant was also detected. The Translocation factor (TF) for cadmium was significantly high in lettuce. Enhanced antioxidant enzymatic activity suggests that these enzymes are integrally involved in the defense mechanism of the plant to heavy metal stress. Also observed was an increase in total soluble protein, and total phenolic content. Total flavonoid content was not significantly affected. Fourteen genes encoding for ascorbate peroxidase and nineteen genes for superoxide dismutase were identified in lettuce. These enzymes varied from each other with regards to the number of exons and amino acids present, as well as their location within the cell. Plants exhibit various response mechanisms to combat heavy metal contamination.

Study of the contamination rate and change in growth features of lettuce (Lactuca sativa Linn.) in response to cadmium and a survey of its phytochelatin synthase gene

Crops can become contaminated when grown in soils containing heavy metals. Cadmium is a heavy metal that poses a significant health risk to humans. The purpose of this study was to evaluate the effect of cadmium on lettuce (Lactuca sativa Linn) and the contamination risk of lettuce grown in cadmium environments. The results showed that photosynthesis and growth parameters were significantly affected by cadmium. Lettuce has the ability to absorb large amounts of cadmium from the contaminated environment and so is a cadmium hyperaccumulator plant. The study showed that approximately 35% of the total absorbed cadmium is transmitted to aerial and edible parts of lettuce. This study was undertaken as lettuce has the ability to absorb and accumulate high levels of cadmium. There are however are no reports on the PCS gene and the potential for high cadmium accumulation in lettuce. The bioinformatics study revealed that lettuce has two phytochelatin synthase genes that produce 6 PCSs through splicing leading to the ability of lettuce to store high levels of cadmium. These six sequences although different in length have high similarity. Sequence structure, cellular location, three-dimensional structure, phylogeny and a comparison of their catalytic power were evaluated. The high accumulation of cadmium in lettuce and the presence of several PCSs contribute to the accumulation of cadmium in aerial tissues. The cultivation of lettuce in contaminated environments led us to evaluate suspected farms for the presence of cadmium in produce. Lettuce grown in industrial environments contaminated with cadmium can pose a serious threat to human health.

Application of fuzzy fault tree analysis based on modified fuzzy AHP and fuzzy TOPSIS for fire and explosion in the process industry

This study aimed at establishing fault tree analysis (FTA) using expert opinion to compute the probability of an event. To find the probability of the top event (TE), all probabilities of the basic events (BEs) should be available when the FTA is drawn. In this case, employing expert judgment can be used as an alternative to failure data in an awkward situation. The fuzzy analytical hierarchy process as a standard technique is used to give a specific weight to each expert, and fuzzy set theory is engaged for aggregating expert opinion. In this regard, the probability of BEs will be computed and, consequently, the probability of the TE obtained using Boolean algebra. Additionally, to reduce the probability of the TE in terms of three parameters (safety consequences, cost and benefit), the importance measurement technique and modified TOPSIS was employed. The effectiveness of the proposed approach is demonstrated with a real-life case study.

Diversity and species composition of mosquitoes (Culicidae: Diptera) in Noor County, northern Iran

Mosquitoes are highly important as public health problem due to their blood sucking habits and transmitting malaria, arboviruses and other diseases to humans. The present research was undertaken to determine the fauna, abundance, monthly distribution and activity of Culicidae mosquito larvae and adults in Noor County, northern Iran. This cross-sectional, descriptive study was conducted from August 2012 to November 2013 in the rural and urban outskirts of Noor. In each area, natural larval breeding places such as river beds, shallow wells, pits, sewer, marsh, small holes, tracks of animals as well as man-made breeding places like pools and rice paddy fields have been visited monthly for larval collection. To collect adult mosquitoes, human and animal dwellings including bedrooms, store rooms, toilets, barns, stables and pen were surveyed using WHO standard methods. A total of 844 larvae and 1484 adult mosquitoes were caught. Of the 665 Culicinae larvae, 501 were Cx. pipiens (75.3%), 108 Cx. mimeticus (16.2%) and 56 Cx. theileri (8.4%). Of the 179 Anophelinae larvae, 96 were An. hyrcanus (53.6%) and 83 An. maculipennis s.l. (46.4%). Among 889 adult Culicinae, 495 were Cx. pipiens (55.7%), 238 Cx. mimeticus (26.8%), 156 Cx. theileri (17.6%), and from 595 adult Anophelinae 371 were An. hyrcanus (62.4%) and 224 An. maculipennis (37.7%). Anopheles hyrcanus with 96 larvae (53.6%) and 371 adults (62.4%) and Cx. pipiens with 501 larvae (75.3%) and 495 adults (55.7%) showed the highest abundance and distribution in the county calling for more studies on their population, ecology, behavior and probable roles as vectors of various diseases.

Evaluation of groundwater quality and assessment of scaling potential and corrosiveness of water samples in Kadkan aquifer, Khorasan-e-Razavi Province, Iran

The chemical analysis of 129 groundwater samples in the Kadkan area, Khorasan-e-Razavi Province, NE of Iran was evaluated to determine the hydrochemical processes, assessment of groundwater quality for irrigation purposes, corrosiveness, and scaling potential of the groundwater. Accordingly, the suitability of groundwater for irrigation was evaluated based on the sodium adsorption ratio, residual sodium carbonate, sodium percent, salinity hazard, and US Salinity Laboratory hazard diagram. Based on the electrical conductivity and sodium adsorption ratio, the dominant classes are C3-S1, C3-S2, C2-S1, and C4-S2. According to the Wilcox plot, about 50 % of the samples fall in the "Excellent to Good" and "Good to Permissible" classes. Besides, the Langelier saturation index, Ryznar stability index (RSI), Larson-Skold index, and Puckorius scaling index were evaluated for assessing the corrosiveness and scaling potential of the groundwater. Corrosiveness and scaling indices stated that the majority of samples are classified into "Aggressive" and "Very Aggressive" category. In addition, chloride and sulfate interfere in 90 % of the samples. Assessment of hydrochemical characteristics indicates Na-Mg-Cl as the predominant hydrochemical type. Spatial distribution of hydrochemical parameters indicates that hydrochemical processes are influenced by geology and hydrogeology of Kadkan aquifer. The Gibbs plots gave an indication that groundwater chemistry in this area may have acquired the chemistry mainly from evaporation and mineral precipitation. Grouping the samples based on Q-mode hierarchical cluster analysis helped to more separation of similar samples. The R-mode HCA grouped analyzed parameters into two groups based on similarity of hydrochemical characteristics. As a result, the samples collected in northern and southern parts of the study area show the best quality (i.e., lowest salinity) for some purposes such as irrigation and drinking.

TRPA1 and TRPV4 activation in human odontoblasts stimulates ATP release

The mechanism of pain in dentine hypersensitivity is poorly understood but proposed to result from the activation of dental sensory neurons in response to dentinal fluid movements. Odontoblasts have been suggested to contribute to thermal and mechanosensation in the tooth via expression of transient receptor potential (TRP) channels. However, a mechanism by which odontoblasts could modulate neuronal activity has not been demonstrated. In this study, we investigated functional TRP channel expression in human odontoblast-like cells and measured ATP release in response to TRP channel activation. Human immortalized dental pulp cells were driven toward an odontoblast phenotype by culture in conditioned media. Functional expression of TRP channels was determined with reverse transcription polymerase chain reaction and ratiometric calcium imaging with Fura-2. ATP release was measured using a luciferin-luciferase assay. Expression of mRNA for TRPA1, TRPV1, and TRPV4 but not TRPM8 was detected in odontoblasts by reverse transcription polymerase chain reaction. Expression of TRPV4 protein was detected by Western blotting and immunocytochemistry. The TRPA1 agonists allyl isothiocyanate and cinnamaldehyde and the TRPV4 agonist GSK1016790A caused a concentration-dependent increase in intracellular Ca(2+) concentration that was inhibited by the selective antagonists HC030031, AP18, and HC067047, respectively. In contrast, exposure to the TRPV1 agonist capsaicin or the TRPM8 agonist icilin had no effect on intracellular Ca(2+) concentration. Treatment with allyl isothiocyanate, cinnamaldehyde, or GSK1016790A caused an increase in ATP concentration in culture medium that was abolished by preincubation with TRP channel antagonists. These data demonstrate that activation of TRPA1 and TRPV4 channels in human odontoblast-like cells can stimulate ATP release. We were unable to confirm the presence of thermosensitive TRPV1 and TRPM8 that has previously been reported in odontoblasts.

Efficacy of Olyset long-lasting bednets to control transmission of cutaneous leishmaniasis in Iran

A large-scale intervention field trial of the effect of Olyset long-lasting insecticide-treated bednets on transmission of cutaneous leishmaniasis was carried out in 2 cities in the Islamic Republic of Iran from October 2003 to July 2005. We enrolled 8620 individuals in 3000 households in 6 pairs of sectors in each city. Epidemiological and entomological surveys were carried out pre- and post-intervention. In both cities a statistically significant reduction was found in the incidence of new cases in intervention sectors who received bednets compared with control areas. Entomological surveys showed a reduction in numbers of female Phlebotomus sergenti captured indoors in intervention sectors.

Effects of lathyritic drugs and lathyritic demineralized bone matrix on induced and sustained osteogenesis

Demineralized bone matrix was implanted in normal and lathyritic rats. At 2 weeks, the bone that formed in the lathyritic animals had an elevated alkaline phosphatase activity and a reduced calcium content compared with the controls. Four weeks after implantation, these biochemical parameters were reversed, with a decrease in alkaline phosphatase activity and an increase in calcium content to control levels. The histology of the recovered implants revealed new bone formation. Lathyritic demineralized bone matrix was prepared from bones of rats fed beta-aminopropionitrile for 2 weeks (2-week BAPN-DBM) or 4 weeks (4-week BAPN-DBM), and was implanted in normal rats. Two weeks after implantation, both preparations of lathyritic demineralized bone matrix demonstrated early bone formation, although alkaline phosphatase activity and calcium content were reduced. By 4 weeks after implantation, no biochemical or histological evidence of bone formation remained at the site of the 4-week BAPN-DBM implants; continued but reduced bone formation was observed at the site of the 2-week BAPN-DBM implants. Reconstitution of inactivated normal demineralized bone matrix with the guanidine-soluble extracts restored the osteoinductive capacity. However, reconstitution of inactivated lathyritic demineralized bone matrix (4-week BAPN-DBM) failed to restore the osteoinductive capacity. These results indicate that the degree of crosslinking of the collagen matrix that acts as a carrier for osteoinductive proteins plays a key role in inducing and sustaining osteogenesis.

Demineralized bone matrix polydioxanone composite as a substitute for bone graft: a comparative study in rats

Demineralized bone matrix (DBM) has been successfully used as a substitute for bone grafting. Autogenous bone grafts (ABG) may cause donor site morbidity and undergo significant resorption. DBM may overcome these problems but is mechanically unstable when originally placed. We explored using a slowly resorbable template, polydioxanone (PDS), in combination with DBM and compared it to ABG in a rat 9 x 9 mm cranial defect model. After both 1 and 3 months, histologically and biochemically well-formed bone was present in ABG/PDS and DBM/PDS-treated defects, but not in control defects (PDS alone). Mechanical push-out tests using a servohydraulic testing frame were conducted. Maximum load before failure of DBM/PDS increased from 65% at 1 month to 100% of that of intact skull at 3 months. In contrast, ABG/PDS was 50% as strong as DBM/PDS and not significantly stronger than PDS alone. ABG/DBM did not significantly increase in strength from 1 to 3 months. We conclude that DBM/PDS is better than ABG/PDS in treating cranial defects in the rat model, and that an absorbable osteoinductive bone substitute with superior mechanical advantage is possible without the disadvantages of ABG.

Effects of non-steroidal anti-inflammatory drugs on demineralized bone-induced bone formation

The inhibitory effect of some non-steroidal anti-inflammatory drugs (NSAIDs) on bone resorption is well documented. To explore the effect of NSAIDs on bone formation, we investigated the time course and dose/response characteristics of treatment with various non-steroidal anti-inflammatory drugs (NSAIDs) on ectopic bone formation induced by demineralized bone matrix (DBM) in the rat model. Using biochemical assays, both inhibitory and stimulatory effects on bone formation were found in rats treated with NSAIDs prior to DBM implantation depending on the type and amount of drug administered. There appears to be an enhancement of bone formation for acetaminophen (50 mg/kg), acetylsalicylic acid (50 mg/kg), and ibuprofen (50 mg/kg). Indomethacin (4 mg/kg) and piroxicam (4 mg/kg) had inhibitory effects. Flurbiprofen, on the other hand, did not appear to affect bone formation significantly. In contrast, there was no effect of NSAIDs on bone formation in rats treated with the drugs after implantation of the DBM. It appears that the time course of the drug administration is critical, suggesting that early events in bone formation may be modulated by arachidonic acid metabolites.

Effects of indomethacin on demineralized bone-induced heterotopic ossification in the rat

Indomethacin inhibits bone formation when treatment is initiated before the implantation of demineralized bone matrix (DBM). For the inhibition of bone induction to occur, indomethacin treatment had to be initiated 6 h or more before implantation of DBM. Initiating the drug treatment at or after the time of DBM implantation had no effects on the amounts of new bone formed. The inhibition by indomethacin is dose related over a range between 0.04 and 4 mg/kg body weight. Recovered day-1 DBM implants, transplanted into indomethacin pre- and posttreated syngeneic rats, formed bone at the same rate as controls did. However, recovered day-1 DBM implants lyophilized before transplantation showed decreased bone formation but significant dystrophic calcification as judged by a lower alkaline phosphatase activity and an elevated calcium content.

Postmortem degradation of demineralized bone matrix osteoinductive potential. Effect of time and storage temperature

The osteoinductive growth factors present in demineralized bone are degraded by tissue enzymes. Storage of rat limbs at low temperature (4 degrees C) before harvesting of bones preserves the osteoinductive potential of such factors. Storage at room temperature for more than 24 hours causes the recovered bone matrix to be biologically inactive, presumably as the result of biodegradation.

Osteogenesis in bone defects in rats: the effects of hydroxyapatite and demineralized bone matrix

Hydroxyapatite (HA) and Demineralized Bone Matrix (DBM) are being investigated as potential osteogenic agents with hopes that these substances can be used to induce bone formation in non-union fractures. This study was done to determine the relative effects of HA and DBM implanted as moldable phospholipid composites in bone defects that result in non-unions. We studied 22 ten-month-old Long-Evans male rats with 5.0 mm unilateral radial defects implanted with HA, DBM, and a combination of both substances. Control defects were left unfilled. Eight weeks after implantation, the histological sections demonstrated a decrease in bone formation with HA relative to controls. The HA crystals were encapsulated by connective tissue stroma made up of collagenous elements, fibroblasts, and blood vessels. There were no indications of bone formation within the fibrous stroma. 45Calcium, alkaline phosphatase, and bone gla protein (BGP) assays demonstrated a 16% increase in bone formation in rats implanted with DBM, an 80% decrease in groups implanted with HA (p = 0.01) and an 80% decrease with DBM plus HA (p = 0.01). Radiologic analysis corresponds well with histological and biochemical results. We conclude that osteogenesis in non-union defects is enhanced by the implantation of DBM, while HA interferes with bone formation in the rat model. In the presence of both substances, HA appears to impede new bone growth, negating any positive effects seen with DBM.