ABSTRACT
Metal-organic framework (MOF)-based derivatives have been found to be promising heterogeneous catalysts for organic transformations. Herein, hollow-structure Cu-MOFs derived by reduction of Cu3 (BTC)2 (BTC=1,3,5-benzenetricarboxylate; denoted as RCB) were prepared by using hydrazine hydrate as a reducing agent under various conditions. The influence of hydrazine hydrate induced the structure of Cu3 (BTC)2 and led to dynamic variation in the interior and exterior as well as oxidation states of the Cu ion. The synthesized materials were characterized by SEM, TEM, N2 sorption isotherms, XRD, and XPS. The product of the catalytic reaction was observed by GC-MS. In addition, the prepared RCBs were found to have excellent catalytic activity and selectivity for benzyl alcohol oxidation when assisted by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO).
ABSTRACT
Wild birds are exposed to insecticides in a variety of ways, at different dose levels and via multiple routes, including ingestion of contaminated food items, and dermal, inhalation, preening, and embryonic exposure. Most poisoning by insecticides occurs as a result of misuse or accidental exposure, but intentional killing of unwanted animals also occurs. In this study, we investigated insecticides in the gastric contents of dead wild birds that were suspected to have died from insecticide poisoning based on necropsy. The wild birds were found dead in various regions and locations such as in mountains, and agricultural and urban areas. A total of 182 dead wild birds of 27 species were analyzed in this study, and insecticide residue levels were determined in 60.4% of the total samples analyzed. Monocrotophos and phosphamidon were the most common insecticides identified at rates of 50.0% and 30.7% of the insecticide-positive samples, respectively. Other insecticides identified in dead wild birds included organophosphorous, organochlorine and carbamate insecticides. However, there was limited evidence to conclusively establish the cause of death related to insecticides in this study. Nevertheless, considering the level of insecticide exposure, it is speculated that the exposure was mainly a result of accidental or intentional killing, and not from environmental residue.
Subject(s)
Animals, Wild , Birds , Environmental Monitoring/statistics & numerical data , Insecticides/analysis , Pesticide Residues/analysis , Animals , Gastrointestinal Contents/chemistry , Republic of KoreaABSTRACT
Eurasian otters (Lutra lutra) are endangered worldwide, but the specific cause of their decline has not been determined. This study analyzed the concentrations of potentially toxic trace elements, including As, Cd, Pb, Hg, Se, Cu, Mn, and Zn, in the liver, kidney, and lung tissues of Eurasian otters in South Korea. There were high individual variations in the tissue concentrations of all the elements analyzed. The kidneys had the highest concentrations of Cd and Se among the three tissue groups, and the livers had the highest concentrations of Cu, Mn, Zn, and Hg. The Pb and As concentrations in the livers were not significantly different from those in the kidneys, and the lungs had the lowest concentrations of all the elements analyzed. The age-related bioaccumulation of Cd and Hg was evident in the three tissue groups, and of Se in the kidneys. The Pb concentration was higher in the livers of juveniles compared with those of adults and the Zn concentration was higher in the lungs of juveniles. There were no apparent gender differences in the concentrations of the elements analyzed among the tissue groups. The Se concentration correlated with the Hg concentration in the livers and kidneys, and with the Cd concentration in the kidneys. The Hg and Cd levels correlated in the three tissue groups. The Cu and Zn levels also correlated in the livers and kidneys. In general, the element concentrations were within the ranges reported by previous studies of this species from European countries, except for Cd and Hg, the levels of which were mostly lower than those reported previously. These findings may provide baseline information to facilitate the conservation of the Eurasian otter. To the best of our knowledge, this is the first available study of trace element concentrations in the tissues of Eurasian otters from South Korea or Asian countries.
Subject(s)
Otters/physiology , Trace Elements/analysis , Water Pollutants, Chemical/analysis , Age Factors , Animals , Endangered Species , Female , Kidney/chemistry , Liver/chemistry , Lung/chemistry , Male , Republic of KoreaABSTRACT
Arsenic is an environmental pollutant, and its liver toxicity has long been recognized. The effect of arsenic on liver protein expression was analyzed using a proteomic approach in monkeys. Monkeys were orally administered sodium arsenite (SA) for 28 days. As shown by 2D-PAGE in combination with MS, the expression levels of 16 proteins were quantitatively changed in SA-treated monkey livers compared to control-treated monkey livers. Specifically, the levels of two proteins, mortalin and tubulin beta chain, were increased, and 14 were decreased, including plastin-3, cystathionine-beta-synthase, selenium-binding protein 1, annexin A6, alpha-enolase, phosphoenolpyruvate carboxykinase-M, erlin-2, and arginase-1. In view of their functional roles, differential expression of these proteins may contribute to arsenic-induced liver toxicity, including cell death and carcinogenesis. Among the 16 identified proteins, four were selected for validation by Western blot and immunohistochemistry. Additional Western blot analyses indicated arsenic-induced dysregulation of oxidative stress related, genotoxicity-related, and glucose metabolism related proteins in livers from SA-treated animals. Many changes in the abundance of toxicity-related proteins were also demonstrated in SA-treated human hepatoma cells. These data on the arsenic-induced regulation of proteins with critical roles may help elucidate the specific mechanisms underlying arsenic-induced liver toxicity.
Subject(s)
Arsenites/toxicity , Liver/drug effects , Proteins/analysis , Proteome/drug effects , Sodium Compounds/toxicity , Animals , Electrophoresis, Gel, Two-Dimensional , Hep G2 Cells , Histocytochemistry , Humans , Liver/chemistry , Liver/metabolism , Macaca fascicularis , Male , Proteins/metabolism , ProteomicsABSTRACT
Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. However, the unique properties of AgNPs could potentially lead to unexpected hazards to both human health and the well being of the environment. Possible mechanisms of AgNP-induced toxicity include the stimulation of oxidative stress, genotoxicity and apoptosis. In this study, a number of previous studies are therefore summarized that demonstrate oxidative stress-, genotoxicity- and apoptosis-related changes brought about by AgNPs in cultured cells and animal tissues. The physicochemical properties of AgNPs that are involved in encouraging such changes are also discussed.
Subject(s)
Apoptosis/drug effects , DNA Damage , Metal Nanoparticles/toxicity , Mutagens/toxicity , Oxidative Stress/drug effects , Silver/toxicity , Animals , Cells, Cultured , Humans , Reactive Oxygen Species/metabolismABSTRACT
Currently, the trend of elderly people living alone is rising due to rapid aging and shifts in family structures. Accordingly, the efficient implementation and management of monitoring systems tailored for elderly people living alone have become paramount. Monitoring systems are generally implemented based on multiple sensors, and the collected data are processed on a server to provide monitoring services to users. Due to the use of multiple sensors and a reliance on servers, there are limitations to economical maintenance and a risk of highly personal information being leaked. In this paper, we propose an intelligent monitoring system with privacy preservation based on edge AI. The proposed system achieves cost competitiveness and ensures high security by blocking communication between the camera module and the server with an edge AI module. Additionally, applying edge computing technology allows for the efficient processing of data traffic. The edge AI module was designed with Verilog HDL and was implemented on a field-programmable gate array (FPGA). Through experiments conducted on 6144 frames, we achieved 95.34% accuracy. Synthesis results in a 180 nm CMOS technology indicated a gate count of 1516 K and a power consumption of 344.44 mW.
ABSTRACT
STUDY OBJECTIVE: This study was designed to investigate the possible role of IFN-γ in eosinophil degranulation that occurs during respiratory syncytial virus (RSV) bronchiolitis. METHODS: Sixty-seven infants, 2-24 months old and hospitalized with their first episode of acute RSV bronchiolitis, were selected for this study. Eosinophil-active cytokine and chemokine profiles in nasal lavage supernatants taken within the first 48 h of admission were determined by a multiplex bead array system (Luminex). Comparisons were made with control (Control group) subjects (n = 20). RESULTS: Nasal IFN-γ levels were significantly higher (P < 0.0001) in RSV bronchiolitis (median = 4.4 pg/ml) infants compared to controls (0.0 pg/ml). IFN-γ levels correlated significantly with the levels of nasal eotaxin (r = 0.566, P < 0.0001), RANTES (r = 0.627, P < 0.0001), GM-CSF (r = 0.849, P < 0.0001), and EDN (r = 0.693, P < 0.001). Nasal interleukin (IL)-4, IL-5, and IL-13 were below sensitivity levels in most RSV bronchiolitis and control subjects. CONCLUSION: These results suggest that IFN-γ may play an important role in eosinophilic inflammation in RSV bronchiolitis.
Subject(s)
Bronchiolitis/immunology , Bronchiolitis/metabolism , Eosinophilia/immunology , Interferon-gamma/metabolism , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Virus Infections/metabolism , Bronchiolitis/virology , Chemokine CCL5/metabolism , Child, Preschool , Eosinophil-Derived Neurotoxin/metabolism , Eosinophilia/complications , Female , Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Humans , Infant , Interferon-gamma/analysis , Interleukin-13/metabolism , Interleukin-4/metabolism , Interleukin-5/metabolism , Male , Nasal Lavage Fluid/immunology , Respiratory Syncytial Viruses , Statistics, NonparametricABSTRACT
Recent evidence suggests that social networking sites (SNS) motivate people, in the form of civic engagement, in times of crisis. Yet, there is a lack of empirical investigations that help to understand how SNS use increases civic judgment or participatory behavior. In this study, we examine how the use of SNS in a public health crisis is related to policy support for effective mitigation of risk, particularly focusing on the role of two distinct types of risk perceptions-general and personal risk perceptions. Using an online survey conducted on the issue of fine dust pollution in South Korea (N = 510), this study found that reliance on SNS for learning (i.e., SNS learning dependency) is positively associated with general risk perception, which, in turn, promotes policy support. Moreover, the results revealed a serial mediation process in which SNS learning dependency increases general risk perception, which ultimately increases personal risk perception and policy support. Overall, this study suggests that SNS has the potential to facilitate public engagement in a crisis and that individual motivation to engage with a crisis is not just a function of individual or societal-level risk perception but can be a simultaneous function of different levels of risk perceptions.
Subject(s)
Public Health , Social Networking , Humans , Policy , Republic of Korea , Surveys and QuestionnairesABSTRACT
Catalase protects cells from reactive oxygen species-induced damage by catalyzing the breakdown of hydrogen peroxide to oxygen and water. Arsenite decreases catalase activity; it activates phosphatidylinositol 3-kinase (PI3K) and its key downstream effector Akt in a variety of cells. The PI3K pathway is known to inhibit catalase expression. c-Met, an upstream regulator of PI3K and Akt, is also involved in the regulation of catalase expression. To examine the involvement of c-Met and PI3K pathways in the arsenite-induced downregulation of catalase, catalase mRNA and protein expression were analyzed in the human hepatoma cell line HepG2 treated with arsenite and either an inhibitor of c-Met (PHA665752 (PHA)) or of PI3K (LY294002 (LY)). Arsenite treatment markedly activated Akt and decreased the levels of both catalase mRNA and protein. Both PHA and LY attenuated arsenite-induced activation of Akt. PHA and LY treatment also prevented the inhibitory effect of arsenite on catalase protein expression but did not affect the level of catalase mRNA. These findings suggest that arsenite-induced inhibition of catalase expression is regulated at the mRNA and post-transcriptional levels in HepG2 cells, and that the post-transcriptional regulation is mediated via c-Met- and PI3K-dependent mechanisms.
Subject(s)
Arsenites/pharmacology , Catalase/metabolism , Enzyme Activation/drug effects , Gene Expression Regulation/physiology , Phosphatidylinositol 3-Kinase/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Proto-Oncogene Proteins c-met/metabolism , Catalase/genetics , Chromones/pharmacology , Down-Regulation , Enzyme Activation/physiology , Gene Expression Regulation/drug effects , Hep G2 Cells , Humans , Indoles/pharmacology , Metabolic Networks and Pathways/drug effects , Morpholines/pharmacology , RNA, Messenger/metabolism , Signal Transduction/drug effects , Signal Transduction/genetics , Sulfones/pharmacologyABSTRACT
People often experience strong emotions during public health crises. This study examines how these emotions shape the perception of risk and support for policies to address the risk. In particular, this study explores the moderating effects of social network services (SNS) use in the process, considering that SNS have become a prominent communication platform during crises. Using a nationwide online survey conducted on the issue of fine dust air pollution in South Korea, this study found that feelings of anxiety, anger, and sadness about the risk issue were positively related to risk perception and policy support, while the relative effects of these emotions varied. Furthermore, the results demonstrated that reliance on SNS for learning (i.e., SNS learning dependency) moderated the influence of anxiety: the positive impact of anxiety was greater among those who used SNS for learning, while no such effects were found among those who used SNS for play or entertainment (i.e., SNS entertainment dependency). The implications of this study are discussed in terms of the distinct role emotions play in public responses to risks and the importance of considering the impact of SNS on public perceptions and judgments in this era of social media.
Subject(s)
Public Health , Social Media , Emotions , Humans , Perception , PolicyABSTRACT
This study examines how attention to science and political news may influence the way people feel about an environmental risk, and how this in turn impacts policy preferences. Using an online survey conducted on the issue of fine dust pollution in South Korea, this study found that science news attention was associated with greater anxiety and anger about the issue, whereas political news attention was associated with fear and sadness/depression (as well as anxiety and anger). Furthermore, mediation analysis showed that science news attention indirectly influenced support for preventive policy through anxiety, whereas political news attention indirectly influenced punitive policy support through anger and fear. Theoretical and practical implications of this study are discussed.
Subject(s)
Emotions , Public Health , Dust , Humans , Policy , Republic of KoreaABSTRACT
This study evaluated the virucidal efficacy of acidic electrolyzed water (AEW) against African swine fever virus (ASFV) and avian influenza virus (AIV), according to the Animal and Plant Quarantine Agency (APQA) guidelines for efficacy testing of veterinary disinfectants. AEW (pH 5.0-6.5) was prepared using a commercially available "Electrolyzed Water Generator" with a free chlorine concentration (FCC) of 5-140 ppm, and its efficiency in reducing the titer of ASFV and AIV was tested in a suspension under low- and high-level organic soiling. Under low-level organic soiling conditions, AEW with FCC ≥40 ppm was effective against ASFV; under high-level organic soiling conditions, AEW with FCC ≥80 ppm was effective against ASFV. Under low-level organic soiling conditions, AEW with FCC ≥60 ppm was effective against AIV; under high-level organic soiling conditions, AEW with FCC ≥100 ppm was effective against AIV. The virucidal effect of AEW seemed dependent on the FCC and the presence of organic soiling. Based on these data, we recommend the following minimum FCCs in AEW treatment for routine disinfection in veterinary field under low- and high-level organic soiling conditions: for ASFV, 50 ppm and 100 ppm; and for AIV, 75 ppm and 125 ppm, respectively. In conclusion, the virucidal effects of AEW against ASFV and AIV emphasize its potential utility as a disinfectant, and we suggest considering organic soiling conditions while using AEW for implementing effective control measures for field applications.
Subject(s)
African Swine Fever Virus/drug effects , Disinfectants/pharmacology , Influenza in Birds/drug therapy , Swine Diseases/virology , Water/chemistry , Animals , Chickens , Disinfection , Electrolysis/methods , Electrolysis/veterinary , Hydrogen-Ion Concentration , Influenza in Birds/virology , Swine , Swine Diseases/drug therapyABSTRACT
BACKGROUND: It has been suggested that the altered iron metabolism in liver tumors, characterized by the iron-deficient phenotype, is of importance for tumor growth. AIM: This study was performed to elucidate the mechanisms underlying iron deficiency in liver tumors by examining how the liver tumor development affects the expression of iron metabolism-related genes. METHODS: Iron metabolism reference values were analyzed in the sera of diethylnitrosamine-induced hepatocellular adenoma-bearing mice. Expression of iron metabolism-related genes was analyzed in adenomas and surrounding non-tumor tissues, and a subgroup of adenoma-bearing mice loaded with iron 72h before sacrifice. RESULTS: Iron content of the adenoma tissues was 2.0-2.5-fold lower compared to surrounding and age-matched control tissues. There was no significant difference in serum iron levels between the adenoma-bearing and control mice, while the adenoma-bearing mice exhibited a 2.4-fold lower level of serum transferrin saturation. Expression of iron metabolism-related genes was dysregulated in the adenomas. Iron loading affected protein expression similarly in the adenomas and surrounding tissues suggesting that iron-responsive regulation of the proteins was not impaired. However, the mRNA expression for ceruloplasmin and divalent metal transporter 1 (DMT1) IRE(+) in the adenomas was altered independently of iron status, and the dysregulation may contribute to diminished iron content. CONCLUSION: These findings suggest that diethylnitrosamine-induced liver adenoma-bearing mice have abnormal iron metabolism and that dysregulation of iron metabolism-related genes contributes to iron deficiency in the adenomas.
Subject(s)
Adenoma, Liver Cell/genetics , Gene Expression Regulation, Neoplastic , Iron/metabolism , Liver Neoplasms, Experimental/genetics , Adenoma, Liver Cell/chemically induced , Adenoma, Liver Cell/metabolism , Animals , Antimicrobial Cationic Peptides/genetics , Antimicrobial Cationic Peptides/metabolism , Cation Transport Proteins/genetics , Cation Transport Proteins/metabolism , Ceruloplasmin/genetics , Ceruloplasmin/metabolism , Copper/metabolism , Diethylnitrosamine , Ferritins/genetics , Ferritins/metabolism , Hepcidins , Immunoblotting , Injections, Subcutaneous , Iron/blood , Iron-Dextran Complex/administration & dosage , Liver Neoplasms, Experimental/chemically induced , Liver Neoplasms, Experimental/metabolism , Male , Mice , Mice, Inbred C3H , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Transferrin/metabolismABSTRACT
Apx toxins have been identified as important virulence factors of Actinobacillus pleuropneumoniae, the etiologic agent of porcine pleuropneumonia. In some A. pleuropneumoniae serotypes, Apx toxins are secreted by the cell membrane proteins encoded by apxIIIB and apxIIID genes. In an effort to develop a live vaccine strain against A. pleuropneumoniae, we inactivated the apxIIIB and apxIIID genes in A. pleuropneumoniae 1536, a serotype 2 strain, resulting in the DeltaapxIIIB/DapxIIID mutant strain (1536DeltaBDeltaD). Immunization of pigs with live 1536DeltaBDeltaD A. pleuropneumoniae conferred protection against homologous challenge with wild-type A. pleuropneumoniae 1536. Thus, impaired Apx toxin secretion may decrease the virulence of A. pleuropneumoniae and may be an effective strategy for the development of a live-attenuated A. pleuropneumoniae vaccine.
Subject(s)
Actinobacillus pleuropneumoniae/classification , Actinobacillus pleuropneumoniae/genetics , Bacterial Proteins/genetics , Actinobacillus pleuropneumoniae/pathogenicity , Gene Deletion , Gene Expression Regulation, Bacterial/physiology , Serotyping , VirulenceABSTRACT
Acetylcholinesterase (AChE) activity level can be used as a diagnostic marker for anticholinesterase pesticide poisoning. In this study, we aimed to establish a baseline level of normal brain AChE activity in wild birds. AChE activity was measured in the brains of 87dead wild birds (26 species). The level of AChE activity ranged from 6.40 to 15.9 µmol/min/g of brain tissue in normal wild birds. However, the brain tissue AChE activity level in wild birds exposed to organophosphate (OP) pesticide was 48.0%-96.3% of that in the normal birds. These results may serve as reference values to facilitate routine diagnosis and monitoring of OP-poisoned wild birds.
Subject(s)
Acetylcholinesterase/metabolism , Bird Diseases/chemically induced , Birds/metabolism , Brain/enzymology , Organophosphate Poisoning/veterinary , Animals , Animals, Wild , Bird Diseases/diagnosis , Bird Diseases/enzymology , Organophosphate Poisoning/diagnosis , Organophosphate Poisoning/enzymology , Reference Values , Republic of KoreaABSTRACT
Mesoporous SiO2-supported Cu2O nanoparticles as an egg-shell type catalyst were prepared by impregnation method. The obtained Cu2O/SiO2 egg-shell nanocatalyst had a large surface area and narrow pore size distribution. In addition, most of the Cu2O nanoparticles, with sizes around 2.0 nm, were highly dispersed in the mesoporous silica. Accordingly, fast reactant diffusion to the active sites would occur, especially when the active metal sites are selectively located on the outer part of the support, i.e., the outer region of the egg shell. In solvent-free Sonogashira reactions for the synthesis of ynones from acyl chlorides and terminal alkynes, this catalyst exhibited a very high catalytic activity. The excellent catalytic performance can be attributed to the synergistic advantages of mesoporous structure and monodispersed Cu2O nanoparticles.
ABSTRACT
Nonalcoholic fatty liver disease (NAFLD) is categorized into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH) and has emerged as a risk factor for more critical clinical conditions. However, the underlying mechanisms of NAFLD pathogenesis are not fully understood. In this study, expression of proteins associated with endoplasmic reticulum (ER) stress, apoptosis and autophagy were analyzed in normal, NAFL and NASH human livers by western blotting. Levels of some ER stress-transducing transcription factors, including cleaved activating transcription factor 6, were higher in NASH than in the normal tissues. However, the expression of a majority of the ER chaperones and foldases analyzed, including glucose-regulated protein 78 and ER protein 44, was lower in NASH than in the normal tissues. Levels of apoptosis markers, such as cleaved poly (ADP-ribose) polymerase, were also lower in NASH tissues, in which expression of some B-cell lymphoma-2 family proteins was up- or down-regulated compared to the normal tissues. The level of the autophagy substrate p62 was not different in NASH and normal tissues, although some autophagy regulators were up- or down-regulated in the NASH tissues compared to the normal tissues. Levels of most of the proteins analyzed in NAFL tissues were either similar to those in one of the other two types, NASH and normal, or were somewhere in between. Together, these findings suggest that regulation of certain important tissues processes involved in protein quality control and cell survival were broadly compromised in the NAFLD tissues.
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Physicochemical properties and oxidative stabilities of mealworm (Tenebrio molitor) oils under different roasting conditions were investigated. Oils were extracted using n-hexane from mealworms roasted at 200°C for 0, 5, 10, and 15 min and physicochemical properties and oxidative stabilities of oils were analyzed. Roasting increased the color intensity and the oleic acid and δ-tocopherol contents, but decreased linoleic acid, and α- and γ-tocopherol contents. An improvement in oxidative stability was observed in roasted mealworm oils, demonstrated by induction time and peroxide values. Mealworm oil contained abundant essential fatty acids and exhibited a superior oxidative stability.
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To clarify the role of stem cells in hepatocarcinogenesis, the expression of epithelial cell adhesion molecule (EpCAM) and proliferating cell nuclear antigen (PCNA) was investigated in mouse hepatic tumors and embryonic cell lineages. Ten ICR mice were treated with diethylnitrosamine (DEN) at 14 days of age and sacrificed at 36 weeks subsequent to DEN treatment to obtain the hepatic tumors. Mouse embryonic stem cells, hepatic progenitor cells and hepatocyte-like cells, representing 0, 22 and 40 days of differentiation, respectively, were treated in vitro with DEN at four doses (0, 1, 5 and 15 mM; G1, G2, G3 and G4, respectively) for 24 h and RNA was isolated. A total of 71 hepatic tumors were obtained from the DEN-treated mice. EpCAM expression was increased mainly in hepatic tumor cells, although it was also detected in the surrounding visually normal cells. Double staining showed that EpCAM and PCNA were co-expressed in numerous tumor cells. In vitro, EpCAM expression was significantly different for G4 at day 0 (P<0.01) and for G2, G3 and G4 at day 40 (P<0.01) compared with the control (G1) at the corresponding time-point. PCNA expression was significantly different for G3 and G4 at day 0 (P<0.01), for G2, G3 and G4 at day 22 (P<0.01) and for G2 at day 40 (P<0.01) compared with G1 at the corresponding time-point. In summary, the expression of EpCAM and PCNA was increased in DEN-induced tumors and the expression of EpCAM and PCNA was altered by DEN treatment in cultured cells. This suggests that EpCAM expression may be modulated in the progeny of adult liver stem cells during their differentiation toward hepatocytes and may be increased during DEN-induced hepatocarcinogenesis.
ABSTRACT
OBJECTIVE: To identify a subantimicrobial dose of doxycycline hyclate (SDD) and for the treatment of periodontitis in dogs. ANIMALS: 20 healthy Beagles for measurement of serum doxycycline concentration and 15 Beagles with periodontitis for evaluation of the efficacy of the SDD. PROCEDURES: 5 dogs each received doxycycline hyclate PO at a dose of 1, 2, 3, or 5 mg/kg. Blood samples were collected before and after administration, and serum concentrations of doxycycline were measured via high-performance liquid chromatography. Mean serum doxycycline concentrations were calculated, and SDDs were identified. In a separate trial, the identified SDDs (1 or 2 mg/kg) were administered PO once a day for 1 month to dogs with periodontitis (n = 5/group) and a control group (5) was fed vehicle only during the same period. Degree of gingival attachment and bleeding on probing (present or absent) were recorded. Gingival samples were collected before and after the 1-month period from the same anatomic sites. Degree of matrix metalloproteinase inhibition in gingival samples was determined via gelatin zymography and compared among treatment groups. RESULTS: Mean serum doxycycline concentrations in healthy dogs that received 1 or 2 mg of doxycycline/kg were consistently significantly lower than the minimal inhibitory doxycycline concentration for treatment of periodontitis throughout the 24-hour posttreatment period. Zymographic intensities were lower in dogs given 1 and 2 mg/kg than in the control dogs, and the degree of gingival attachment and bleeding significantly improved in dogs given 2 mg/kg, compared with in the control dogs and dogs given 1 mg of doxycycline/kg. CONCLUSIONS AND CLINICAL RELEVANCE: A doxycycline dosage of 2 mg/kg daily appeared to be an appropriate subantimicrobial regimen for dogs with periodontitis. Furthermore, this dosage may be suitable for long-term treatment of gelatinolytic inflammatory diseases such as periodontitis in this species.