The role of phenotypic plasticity and corticosterone in coping with pond drying conditions in yellow-bellied toad (Bombina variegata, Linnaeus 1758) tadpoles.

Amphibian larvae inhabiting temporary ponds often exhibit the capacity to accelerate development and undergo metamorphosis in challenging conditions like desiccation. However, not all species exhibit this ability, the yellow-bellied toad (Bombina variegata) is one such example. The underlying mechanisms behind the inability to accelerate development under desiccation remain largely unexplored. The hypothalamic-pituitary-interrenal (HPI) axis and corticosterone (CORT), which act synergistically with thyroid hormone, are thought to facilitate metamorphosis in response to desiccation stress. In this study, we aimed to investigate whether modification in the HPI axis, particularly CORT levels, contributes to the absence of adaptive plasticity in B. variegata under desiccation stress. The study design included four treatments: high water level, high water level with exogenous CORT, low water level, and low water level with metyrapone (a CORT synthesis inhibitor). The main objective was to evaluate the effects of these treatments on whole-body corticosterone levels, life history, morphological traits, and oxidative stress parameters during the prometamorphic and metamorphic climax developmental stages. While low water level had no effect on total corticosterone levels, larval period, body condition index, and metamorphic body shape, it negatively affected metamorph size, mass, and growth rate. Our findings suggest that constant exposure to desiccation stress over generations may have led to modifications in the HPI axis activity in B. variegata, resulting in adaptation to changes in water level, evident through the absence of stress response. Consequently, CORT may not be a relevant stress indicator in desiccation conditions for this species.

Sinonasal Hamartoma and Chronic Laryngeal Edema Causing Severe Dyspnea.

Background: Sinonasal hamartomas, according to the 5th edition of the World Health Organisation classification of head and neck tumours are divided into respiratory epithelial adenomatoid hamartoma (REAH), seromucinous hamartoma and chondromesenchymal hamartoma. Seromucinous hamartoma are benign proliferations of small eosinophilic glands surrounded by fibrous stroma and cuboidal cells. Hamartomas of the nasal cavity and paranasal sinuses are rare entities, clinically presenting as sinonasal polyposis. Case Presentation: A 79- year-old female patient was referred to our emergency room due to severe dyspnea. Anterior rhinoscopy revealed unilateral greyish polypoid mass obstructing the middle, inferior and common nasal meatus. Systemic corticosteroids and oxygen therapy were administered under observation. Computerized tomographic imaging of the paranasal sinuses with contrast on all three planes showed an opacified polypoid mass in all meatus and the maxillary, anterior ethmoidal and sphenoidal sinus posteriorly extending to the choanae. On the coronal plane a widening of the olfactory clefts about 12 mm was described. FESS visualized that the polypoid mass originated from the posterior septum and extended to all meatus anteriorly and to the choanae posteriorly. The polypoid lesion was endoscopically completely excised. Histopathological analysis revealed a seromucinous hamartoma. Conclusion: Seromucinous hamartoma are rare benign tumors of the sinonasal region with potential of malignant alteration. Unfortunately, they share symptoms and clinical appearance with other benign conditions of the sinonasal region. Therefore, it is even more important to consider them as a differential diagnose.

Does the anesthetic tricaine methanesulfonate (MS-222) distort oxidative status parameters in tadpoles?

The effect of anesthesia/euthanasia with ethyl 3-aminobenzoate methanesulfonate (MS-222) on the oxidative status of Hyla arborea tadpoles was examined to determine whether the use of the anesthetic can confound the experimental results of the oxidative stress-based investigation. The experiment was conducted on two groups of tadpoles reared at different temperatures to produce differences in antioxidant capacity between the groups. After development at different temperatures (20 °C and 25 °C), the animals were exposed to different concentrations of MS-222 (0, 0.1, 1, and 5 g/L) for 15 min. The higher temperature decreased catalase activity, glutathione and protein carbonyl levels and increased glutathione reductase activity. The glutathione level and glutathione/thiol-related parameters were significantly changed after MS-222 exposure. However, individuals from the different temperature groups responded differently to the tested anesthetic, pointing to the possible influence of the initial levels of antioxidant capacity. The analysis of the interaction between the factors (temperature and MS-222) confirmed that the anesthetic can confound the results regarding the effects of temperature on the oxidative status parameters. The concentration of 0.1 g/L MS-222 had the lowest influence on the alterations in oxidative status and the results of the effect of temperature. A brief review of the current literature on the use of MS-222 in tadpoles made clear the absence of precise information on anesthetic concentration and exposure time. Similar studies should be repeated and extended to other amphibian species and other factors of interest to provide better guidance on tadpole anesthesia/euthanasia for future experiments that consider oxidative status parameters.

Implant-supported single all-ceramic crowns made from prefabricated (stock) or individualized CAD/CAM zirconia abutments: A 5 year randomized clinical trial.

AIM: The aim of this randomized, prospective, and clinical multicenter study was to compare the overall clinical performance of two restorative options over a 5-year period: individualized CAD/CAM abutments veneered with a hand-layered ceramic, and prefabricated zirconium dioxide abutments veneered with press ceramic and inserted into a single edentulous gap in the anterior maxilla. MATERIALS AND METHODS: Forty subjects were recruited from two universities: 20 from the University of XX and 20 from the University of XY. Each subject received an implant to restore a single edentulous gap in the maxillary anterior region (14-24 FDI). 20 patients were randomized into each Group. Group A received a one-piece single crown produced from a prefabricated zirconia abutment with pressed ceramic and Group B received an individualized CAD/CAM zirconia abutment with a hand-layered technique. After 5 years, the aesthetic and radiographic parameters were assessed. RESULTS: Group A had four dropouts and one failure, resulting in a 95% survival rate and 95% success rate. Group B had two dropouts and two failures which resulted in a 90% survival rate and 90% success rate. No crestal bone level changes were observed, with a mean DIB of 0.06 mm in Group A and 0.09 mm in Group B. No statistically significant differences were present at baseline, 6 months, 1 year, 3 years, or 5 years for DIB values between time points and groups. Pink aesthetic score/white aesthetic score, Peri-Implant and Crown Index, and Implant Crown Aesthetic Index values were stable over time at all five points for both groups. CONCLUSION: Both implant-supported restorative options represent a valuable treatment option for the restoration of implant crowns in the anterior maxilla. CLINICAL SIGNIFICANCE: In general, the use of ceramic abutments in the anterior zone represents a valuable treatment procedure with both standardized and CAD/CAM individualized abutments and following the recommendations from the respective manufacturer(s).

Ramsay Hunt Syndrome with Pharyngolaryngeal Involvement Mimicking Acute Stroke: A Case Report.

Ramsay Hunt syndrome is a clinical manifestation of the reactivation of latent varicella zoster virus in the geniculate ganglion after acute infection. It is commonly associated with an acute peripheral facial nerve paralysis, auricular vesicular eruption and acute sensorineural hearing loss. However, in some rare cases the involvement of other cranial nerves, especially the glossopharyngeal and vagal is described. We present a 56-year-old male patient who was diagnosed with acute pharyngitis. Two days later, the patient developed dysarthria, hoarseness, and left side facial weakness. Considering a patient's history of cardiovascular events, the acute stroke was suspected. Magnetic resonance imaging ruled out an acute cerebrovascular accident. The patient's otalgia aggravated and he reported hearing loss. Clinical examination revealed facial paralysis affecting the left side of the face, erythematous rash on the left auricle, multiple vesicles present on patient's left tympanic membrane, ulcerous lesion on the left side of the soft palate and ipsilateral velopharyngeal palsy. Indirect laryngoscopy revealed ulcerous lesions in the left side of the epiglottis and left vocal cord paralysis. The patient was diagnosed with Ramsay Hunt syndrome with cranial polyneuropathy. Oral acyclovir and oral prednisolone were administered. Seven months after discharge, facial paralysis improved to lower grade and flexible laryngoscopy showed that the left vocal cord had resumed normal movement. Ramsay Hunt syndrome can be accompanied by involvement of other cranial nerves. Previous history of hypertensive crises and myocardial infarction may influence a diagnosis of Ramsay Hunt syndrome, especially when it has atypical presentation. However, this diagnosis should be considered in patients with unilateral multiple cranial nerve palsies.

Emergency Tracheostomy Due to a Myasthenic Crisis in a Post-COVID Patient: Report of a Case.

Myasthenia gravis is an autoimmune disorder caused by the production of antibodies that block either acetylcholine receptors or structural receptors of the neuromuscular junction. There is expanding evidence that novel coronavirus (2019-nCoV) disease can lead to the development of an autoimmune response. Myasthenic crisis, a life-threatening respiratory muscle weakness severe enough to necessitate intubation or tracheostomy, can be a potential complication of myasthenia gravis. In this report, we describe the case of a 57-year-old man with acute respiratory insufficiency requiring emergency tracheostomy. His health condition rapidly deteriorated 1 week after initiating systemic corticosteroid treatment for a suspected adult-onset asthma exacerbation. The patient had a history of COVID-19 infection and thymectomy, which were noted in his medical records. Serological testing and electrodiagnostic evaluation confirmed the diagnosis of myasthenia gravis. The patient was treated with plasma exchange, continuous neostigmine infusion, and prednisone. He was successfully decannulated and discharged with anticholinesterase inhibitors and long-term immunosuppression therapy. It is important to consider neurological disorders in the differential diagnosis for patients presenting with respiratory insufficiency, particularly during the COVID-19 pandemic.

Higher temperature induces oxidative stress in hybrids but not in parental species: A case study of crested newts.

Ectotherms are particularly sensitive to global warming due to their limited capacity to thermoregulate, which can impact their performance and fitness. From a physiological standpoint, higher temperatures often enhance biological processes that can induce the production of reactive oxygen species and result in a state of cellular oxidative stress. Temperature alters interspecific interactions, including species hybridization. Hybridization under different thermal conditions could amplify parental (genetic) incompatibilities, thus affecting a hybrid's development and distribution. Understanding the impact of global warming on the physiology of hybrids and particularly their oxidative status could help in predicting future scenarios in ecosystems and in hybrids. In the present study, we investigated the effect of water temperature on the development, growth and oxidative stress of two crested newt species and their reciprocal hybrids. Larvae of Triturus macedonicus and T. ivanbureschi, and their T. macedonicus-mothered and T. ivanbureschi-mothered hybrids were exposed for 30 days to temperatures of 19°C and 24°C. Under the higher temperature, the hybrids experienced increases in both growth and developmental rates, while parental species exhibited accelerated growth (T. macedonicus) or development (T. ivanbureschi). Warm conditions also had different effects on the oxidative status of hybrid and parental species. Parental species had enhanced antioxidant responses (catalase, glutathione peroxidase, glutathione S-transferase and SH groups), which allowed them to alleviate temperature-induced stress (revealed by the absence of oxidative damage). However, warming induced an antioxidant response in the hybrids, including oxidative damage in the form of lipid peroxidation. These findings point to a greater disruption of redox regulation and metabolic machinery in hybrid newts, which can be interpreted as the cost of hybridization that is likely linked to parental incompatibilities expressed under a higher temperature. Our study aims to improve mechanistic understanding of the resilience and distribution of hybrid species that cope with climate-driven changes.

What coloration brings: Implications of background adaptation to oxidative stress in anurans.

BACKGROUND: Urban development results in habitat destruction, affecting populations of amphibians, the most fragile group of vertebrates. With changes in the environment, these animals become more exposed to light and predators. To enhance their chances of survival, they display plasticity of body coloration. Aside from adaptive benefits, animals exhibiting background matching meet the energetic costs and restrictions of changing body tones. To study the physiological consequences of Hyla arborea tadpole adaptation to background color, we followed oxidative stress parameters after rearing larvae on a constant background (black/white) and after changing the background color. RESULTS: Larvae cultivated for 20 days on constant substrate color exhibited differences in body coloration but without differences in lipid peroxidation (LPO) concentration between dark and pale individuals, suggesting that coloration investment during this period did not induce higher oxidative damage in darker tadpoles. Prolonged exposure of larvae (37 days) to a dark habitat increased antioxidative system defense and LPO concentrations, compared to animals reared permanently in the white surroundings. The positive correlation of oxidative damage with color intensity of individuals points to the physiological consequences of higher investment in the number of pigment cells necessary for dark pigmentation. In individuals faced with non-matching background and change in body coloration, defense system declined and LPO occurred relative to individuals cultivated in white habitat. CONCLUSION: Here, we have pointed to consequences related to background matching and stress that amphibians experienced during chromatic adaptations. Background color change causes a complex physiological response affecting the antioxidative defense parameters. This investigation elucidates the accompanying cost of amphibians' adjustment to an altered environment.

Carry-Over Effects of Desiccation Stress on the Oxidative Status of Fasting Anuran Juveniles.

Amphibians are sensitive to deteriorating environmental conditions, especially during transition to a terrestrial environment which is full of uncertainties. Harsh conditions, such as desiccation during earlier stages, affect different larval traits with possible carry-over effects on juvenile and adult life histories. The first consequences of the effects can be seen in juveniles in the challenges to find food and the ability to survive without it in a terrestrial habitat. Body size and the internal energy reserves acquired during the larval phase play an important role in this period. Herein, we tested how different water regimes (low water availability, desiccation and constant high-water availability) during larval development reflect on the oxidative status and ability of yellow belly toad (Bombina variegata) juveniles to endure short-term fasting. The desiccation regime significantly reduced the body size of metamorphs. The same was observed after 2 weeks of fasting, while the feeding treatment reduced differences mostly in the body mass of individuals from different water regimes. This was the result of a greater gain in mass in juveniles pre-exposed to desiccation. Pre-exposure to desiccation also modified the parameters of the antioxidant system (AOS) under feeding conditions, leading to higher values of superoxide dismutase, glutathione reductase and glutathione S-transferase, glutathione and sulfhydryl group concentrations, and lower glutathione peroxidase in comparison to juveniles reared under constant water. The increase in the AOS of juveniles can be considered as a physiological carry-over effect of desiccation, probably as the result of compensatory growth and/or earlier exposure to chronic stress. However, water levels during larval development did not exert significant effects on the oxidative status of juveniles subjected to food unavailability. Fasting juveniles, both control and desiccated, were exposed to oxidative stress, significantly higher lipid peroxide concentrations, lower superoxide dismutase, glutathione peroxidase, glutathione S-transferase, glutathione and sulfhydryl group values in comparison to feeding individuals. The lack of food in juvenile anurans activated the AOS response in the same manner, regardless of body size and stress pre-exposure, suggesting that the generally accepted hypothesis about the influence of metamorphic body size on the fitness of the postmetamorphic stage should be tested further.

Oxidative Stress Parameters in Goitrogen-Exposed Crested Newt Larvae (Triturus spp.): Arrested Metamorphosis.

Thiourea is an established disruptor of thyroid hormone synthesis and is frequently used as an inhibitor of metamorphosis. The changes caused by thiourea can affect processes associated with the oxidative status of individuals (metabolic rate, the HPI axis, antioxidant system). We investigated the parameters of oxidative stress in crested newt (Triturus spp.) larvae during normal development in late larval stage 62 and newly metamorphosed individuals, and during thiourea-stimulated metamorphosis arrest in individuals exposed to low (0.05%) and high (0.1%) concentrations of thiourea. Both groups of crested newts exposed to thiourea retained their larval characteristics until the end of the experiment. The low activities of antioxidant enzymes and the high lipid peroxidation level pointed to increased oxidative stress in larvae at the beginning of stage 62 as compared to fully metamorphosed individuals. The activities of catalase (CAT) and glutathione-S-transferase (GST) and the concentration of sulfhydryl (SH) groups were significantly lower in larvae reared in aqueous solutions containing thiourea than in newly metamorphosed individuals. The high thiourea concentration (0.1%) affected the antioxidative parameters to the extent that oxidative damage could not be avoided, contrary to a lower concentration. Our results provide a first insight into the physiological adaptations of crested newts during normal development and simulated metamorphosis arrest.

Impact of desiccation pre-exposure on deltamethrin-induced oxidative stress in Bombina variegata juveniles.

Global warming represents a severe threat to existing ecosystems, especially for anuran tadpoles who encounter significant fluctuations in their habitats. Decreasing water levels in permanent and temporary water bodies is a significant risk for larval survival or fitness. On the other hand, the natural environment of amphibians is extremely polluted by various xenobiotics. This study evaluated how pre-exposure of Bombina variegata tadpoles to chronic environmental stress (desiccation) modulates the biochemical response of juvenile individuals to following acute chemical stressor (pesticide deltamethrin). Our results demonstrated that individually applied pesticide changed the thiol and lipid status of the treated juveniles but animals subjected solely to desiccation pressure were more tolerant to free radicals and showed no induction of lipid peroxidation. Comparison of juveniles exposed to deltamethrin revealed that desiccation pretreatment during the larval stage of development modified cellular protection in the juveniles. Higher activities of CAT, GSH-Px and GR were recorded in the pre-exposed group, as well as a lower degree of lipid peroxidation relative to the group that was not pre-exposed to low water stress. Pre-desiccated groups displayed the greatest range of coordination of investigated antioxidant parameters, supported by Pearson's correlations. Activation of the GSH-redox system is a significant marker in juveniles against stress caused by desiccation and a chemical stressor. The stressful environment experienced during tadpole development produced an adaptive reaction to subsequent exposure to another stressor in juveniles. To develop relevant management and conservation strategies, more studies of the interactive effects of environmental and chemical stressors are necessary.

Effects of Desiccation on Metamorphic Climax in Bombina variegata: Changes in Levels and Patterns of Oxidative Stress Parameters.

In this paper, we examined how the oxidative status (antioxidant system and oxidative damage) of Bombina variegata larvae changed during the metamorphic climax (Gosner stages: 42-beginning, 44-middle and 46-end) and compared the patterns and levels of oxidative stress parameters between individuals developing under constant water availability (control) and those developing under decreasing water availability (desiccation group). Our results revealed that larvae developing under decreasing water availability exhibited increased oxidative damage in the middle and end stages. This was followed by lower levels of glutathione in stages 44 and 46, as well as lower values of catalase, glutathione peroxidase, glutathione S-transferase and sulfhydryl groups in stage 46 (all in relation to control animals). Comparison between stages 42, 44 and 46 within treatments showed that individuals in the last stage demonstrated the highest intensities of lipid oxidative damage in both the control and desiccation groups. As for the parameters of the antioxidant system, control individuals displayed greater variety in response to changes induced by metamorphic climax than individuals exposed to desiccation treatment. The overall decrease in water availability during development led to increased oxidative stress and modifications in the pattern of AOS response to changes induced by metamorphic climax in larvae of B. variegata.

Studying microplastics: Lessons from evaluated literature on animal model organisms and experimental approaches.

Although we are witnesses of an increase in the number of studies examining the exposure/effects of microplastics (MPs) on different organisms, there are many unknowns. This review aims to: (i) analyze current studies devoted to investigating the exposure/effects of MPs on animals; (ii) provide some basic knowledge about different model organisms and experimental approaches used in studying MPs; and to (iii) convey directions for future studies. We have summarized data from 500 studies published from January 2011 to May 2020, about different aspects of model organisms (taxonomic group of organisms, type of ecosystem they inhabit, life-stage, sex, tissue and/or organ) and experimental design (laboratory/field, ingestion/bioaccumulation/effect). We also discuss and try to encourage investigation of some less studied organisms (terrestrial and freshwater species, among groups including Annelida, Nematoda, Echinodermata, Cnidaria, Rotifera, birds, amphibians, reptiles), and aspects of MP pollution (long-term field studies, comparative studies examining life stages, sexes, laboratory and field work). We hope that the information presented in this review will serve as a good starting point and will provide useful guidelines for researchers during the process of deciding on the model organism and study designs for investigating MPs.

Hepatic oxidative stress and neurotoxicity in Pelophylax kl. esculentus frogs: Influence of long-term exposure to a cyanobacterial bloom.

Although the long-term exposure of aquatic organisms to cyanobacterial blooms is a regular occurrence in the environment, the prooxidant and neurotoxic effects of such conditions are still insufficiently investigated in situ. We examined the temporal dynamics of the biochemical parameters in the liver of Pelophylax kl. esculentus frogs that inhabit the northern (N) side of Lake Ludas (Serbia) with microcystins (MCs) produced in a cyanobacterial bloom over three summer months. The obtained data were compared with data on frogs that live on the southern (S), MC-free side of the same lake. Our results showed that the MC-producing bloom induced oxidative damage to proteins and lipids, observed as a decrease in the concentration of protein -SH groups and increased lipid peroxidation (LPO) in the liver of N frogs in comparison to S frogs. Glutathione (GSH) played a key role in the transient defense against the MC-induced development of LPO. The low glutathione peroxidase (GPx) activity detected in all groups of frogs from the N site was crucial for the observed prooxidant consequences. The bloom impaired cholinergic homeostasis as a result of a decrease in ChE activity. A delayed neurotoxic effect in relation to the prooxidant outcomes was observed. Our results also showed that even though the integrated biomarker response (IBR) of the antioxidant biomarkers increased during exposure, the individual biochemical parameters did not exhibit a well-defined time-dependent pattern because of specific adaptation dynamics and/or additional effects of the physicochemical parameters of the water. This comprehensive environmental ecotoxicological evaluation of the cyanobacterial bloom-induced biochemical alterations in the liver of frogs provides a new basis for further investigations of the prolonged, real-life ecotoxicity of the blooms.

The effect of short-term fasting on the oxidative status of larvae of crested newt species and their hybrids.

In nature, animals often face periods without food caused by seasonal fluctuations and/or prey scarcity. An organism's physiological response to imposed energetic limitations is followed by changes in mitochondrial functioning (adjustment of energy metabolism) and a reduction of non-essential processes. However, this energy-saving strategy can have its costs. In this study, we examined oxidative stress as one of the possible physiological costs of short-term, two-week-long food deprivation on developing amphibian larvae of the crested newts Triturus macedonicus and Triturus ivanbureschi and their hybrids. We investigated whether this exogenous factor additionally affected the oxidative status (fitness-related trait) of hybrid individuals. The fasting treatment led to lower growth and a lower body mass and body condition index of individuals. The results revealed that the antioxidant system (AOS) of food-deprived larvae could not cope in a proper manner with reactive oxygen species production under limited energy availability, leading to higher lipid oxidative damage. The lowest AOS response was observed for H2O2 scavenging parameters (catalase, glutathione peroxidase, and total glutathione), which together with the elevated activity of superoxide dismutase suggested increased H2O2 concentrations. Comparison between parental species and their hybrids showed that hybrid individuals suffered greater oxidative damage (as demonstrated by higher concentrations of lipid peroxides), indicating that they were more susceptible to fasting-induced oxidative stress. Overall, this study illustrates that: (i) an oxidative event is one of the costs amphibian larvae face during short-term periods of fasting, (ii) hybrids are less capable of dealing with this stressful condition, which can lower their chances of survival in a changing environment.

The Effect of Shelter on Oxidative Stress and Aggressive Behavior in Crested Newt Larvae (Triturus spp.).

Shelters are important for animal survival. Provision of adequate hiding places allow animals to express their natural sheltering behavior and it can have different positive effects on cortisol levels, physiological processes and mental performance. Although the absence of a refuge activates some stress response, its effect on oxidative stress has not been adequately examined. This study investigated whether the presence/absence of a shelter modifies the oxidative status (the antioxidant system and oxidative damage) and aggressive behavior of crested newt larvae (Triturus macedonicus and its hybrid with T. ivanbureschi). Our results show that individuals reared with shelters had lower values of the tested antioxidant parameters (catalase, glutathione peroxidase, glutathione S-transferase and glutathione), indicating a lower production of reactive species than individuals reared without shelter. The same pattern was observed in both T. macedonicus and its hybrid. Contrary to the activation of some physiological pathways, shelter availability did not significantly affect the rate of intraspecific aggressive behavior. The physiological benefits of shelter use can be manifested as a lower requirement for investment in the energy necessary for the maintenance of the upregulated antioxidant defenses, activation of repair systems and synthesis of endogenous antioxidants. This study highlights the importance of shelter provision, which may be valuable in habitat restoration and animal conservation studies.

Clinical and esthetic outcomes of two different prosthetic workflows for implant-supported all-ceramic single crowns-3 year results of a randomized multicenter clinical trail.

OBJECTIVE: The aim of this randomized multicenter clinical trial was to evaluate and compare the performance of anterior all-ceramic implant crowns based either on prefabricated zirconia abutments veneered with pressed ceramics or on CAD/CAM zirconia abutments veneered with the hand build-up technique. The null hypothesis was that there is no statistically significant difference between the two study groups. MATERIAL AND METHODS: Forty implants were inserted in sites 14-24 (World Dental Federation [FDI]) in two centers, the Universities of Bern and Geneva, Switzerland. Twenty patients each were randomized into either Group A and restored with one-piece single crown made of a prefabricated zirconia abutment with pressed ceramic, or Group B using an individualized CAD/CAM zirconia abutment with the hand-layered technique. After 3 years, clinical, esthetic, and radiographic parameters were assessed. RESULTS: Group A exhibited one dropout patient and one failure resulting in a survival rate of 89% after 3 years and two failures for Group B (90%). Clinical parameters presented healthy peri-implant soft tissues. Overall, no crestal bone level changes were observed (mean DIB of 0.13 mm [Group A] and 0.24 mm [Group B]). There were no significant differences at baseline, 6 months, and 1 and 3 years for DIB values between the two groups. PES and WES values evaluated at all three time points indicated stability over time for both groups and pleasing esthetic outcomes. CONCLUSIONS: Both implant-supported prosthetic pathways represent a valuable treatment option for the restoration of implant crowns in the anterior maxilla.

Biochemical parameters in skin and muscle of Pelophylax kl. esculentus frogs: Influence of a cyanobacterial bloom in situ.

There is little information in scientific literature as to how conditions created by a microcystin (MC) producing cyanobacterial bloom affect the oxidant/antioxidant, biotransformation and neurotoxicity parameters in adult frogs in situ. We investigated biochemical parameters in the skin and muscle of Pelophylax kl. esculentus from Lake Ludas (Serbia) by comparing frogs that live on the northern bloom side (BS) of the lake with those that inhabit the southern no-bloom side (NBS). A higher protein carbonylation level and lower antioxidant defense system capability in the skin of frogs living in conditions of the cyanobacterial bloom were observed. Inhibition of glutathione-dependent machinery was the major mechanism responsible for the induction of cyanobacterial bloom-mediated oxidative stress in frog skin. On the other hand, the detected higher ability of muscle to overcome bloom prooxidant toxicity was linked to a higher efficiency of the biotransformation system through glutathione-S-transferase activity and/or was the consequence of indirect exposure of the tissue to the bloom. Our results have also revealed that the cyanobacterial bloom conditions induced the cholinergic neurotransmitter system in both tissues. This study provides a better understanding of the ecotoxicological impact of the MC producing cyanobacterial bloom on frogs in situ. However, further investigations of the complex mechanism involved in cyanobacterial bloom toxicity in real environmental conditions are required.

Oxidative stress in Pelophylax esculentus complex frogs in the wild during transition from aquatic to terrestrial life.

During life, anuran individuals undergo drastic changes in the course of transition from aquatic to terrestrial habitat, when they are faced with metabolically demanding processes (growth, responses to developmental pressures), which result in increased production of reactive oxygen species (ROS), signaling molecules involved in development that can induce oxidative damage and stress. This situation can be further complicated by environmental influences. The aim of this study was to investigate oxidative stress parameters in naturally developing Pelophylax esculentus complex frogs during four developmental periods: premetamorphosis, prometamorphosis, metamorphic climax and juvenile stage, in order to examine changes in the response of the antioxidative system (AOS) and oxidative damage during the transition from aquatic to terrestrial life. Results show that ontogenetic shifts in anurans are accompanied by different levels of damage and AOS responses, which vary from the increased first-line enzymatic activities during the early period of development (premetamorphosis), through increased changes in the non-enzymatic complement during the metamorphic climax, to changes in both the enzymatic and non-enzymatic components observed in juvenile individuals. Premetamorphic individuals and individuals in metamorphosis displayed higher levels of lipid peroxidation, indicating that direct exposure to the environment for the first time and the modulation of organs are the most susceptible stages for oxidative damage. On the other hand, lower oxidative damage in juveniles points to the ability of their AOS to efficiently respond to challenges of the terrestrial environment. This study highlights the importance of ROS and the AOS of anurans in response to different developmental and/or environmental pressures that individuals face.

Do different diets affect oxidative stress biomarkers and metal bioaccumulation in two snake species?

In this study we examined possible differences in heavy metal accumulation and oxidative stress parameters in the liver and muscle of two semi-aquatic snakes: grass snake (Natrix natrix) and dice snake (N. tessellata), that inhabit the same environment but differ in prey diversity. The obtained results revealed some interspecies, inter-tissue, prey-snake and prey-prey differences in heavy metal concentrations. Grass snakes pray contained significantly higher concentrations of Al, Cr and Fe as compared to food of dice snakes. Both investigated snakes accumulated generally lower concentrations of metals than their prey, indicating that they are not at risk of contaminant biomagnification. A significant interspecies difference in accumulation was observed only for Cu and Mn concentrations. On the other hand, analysis of oxidative stress biomarkers showed clear differences between the investigated snake species and the two investigated tissues. The liver of grass snake had increased superoxide dismutase, glutathione reductase and glutathione-S-transferase activities in comparison to dice snake. In muscle, a reverse trend was observed for the activities of these three enzymes, as well as for glutathione peroxidase activity. The higher number of significant correlations observed between oxidative stress biomarkers and heavy metal concentrations in grass snake points to upregulation of the antioxidative system (AOS), which resulted in a lower TBARS concentration. Results show that while the investigated snake species did not differ significantly in the accumulated metals, their defense mechanisms were different. This reveals the complexity of the AOS and points to the cooperation of different AOS components in individuals from natural populations.