PTU Group Research Articles

Protective effect of Korean red ginseng water extract on levothyroxine-induced hyperthyroidism and propylthiouracil-induced hypothyroidism in rats

BackgroundKorean red ginseng extract (KRGE) (Family: Araliaceae) is one of the most widely used traditional herbs in Asia. Multiple studies have shown that KRGE has anti-inflammation, anti-fatigue, anti-obesity, anti-oxidant, and anti-cancer effects. MethodsSprague-Dawley rats were divided into five groups for PTU-induced hypothyroidism and six groups for LT4-induced hyperthyroidism. At the experiment's conclusion, rats were sacrificed, and blood, thyroid gland, and liver samples were collected. Body weight was recorded weekly, and serum hormone levels were assessed using enzyme-linked immunoassay. Thyroid gland and liver tissues were stained with hematoxylin and eosin. KRGE was prepared in 0.5% CMC and stored at 4 °C before administration. ResultsIn the LT4-induced hyperthyroidism model, KRGE prevented decreases in body weight, thyroid gland weight, liver weight, serum glucose, and thyroid hormone levels compared to the PTU group. It also reduced increases in T3, T4, and serum aspartate aminotransferase levels after LT4 treatment. Additionally, KRGE improved thyroid gland and liver histopathology, effects not observed in the PTU-induced hypothyroidism model. ConclusionAll things considered, our research points to KRGE's potential protective role in rat hyperthyroidism caused by LT4 by lowering thyroid hormone production.

Pigment Identification and Gene Expression Analysis during Erythrophore Development in Spotted Scat (Scatophagus argus) Larvae.

Red coloration is considered an economically important trait in some fish species, including spotted scat, a marine aquaculture fish. Erythrophores are gradually covered by melanophores from the embryonic stage. Despite studies of black spot formation and melanophore coloration in the species, little is known about erythrophore development, which is responsible for red coloration. 1-phenyl 2-thiourea (PTU) is a tyrosinase inhibitor commonly used to inhibit melanogenesis and contribute to the visualization of embryonic development. In this study, spotted scat embryos were treated with 0.003% PTU from 0 to 72 h post fertilization (hpf) to inhibit melanin. Erythrophores were clearly observed during the embryonic stage from 14 to 72 hpf, showing an initial increase (14 to 36 hpf), followed by a gradual decrease (36 to 72 hpf). The number and size of erythrophores at 36 hpf were larger than those at 24 and 72 hpf. At 36 hpf, LC-MS and absorbance spectrophotometry revealed that the carotenoid content was eight times higher than the pteridine content, and β-carotene and lutein were the main pigments related to red coloration in spotted scat larvae. Compared with their expression in the normal hatching group, rlbp1b, rbp1.1, and rpe65a related to retinol metabolism and soat2 and apoa1 related to steroid hormone biosynthesis and steroid biosynthesis were significantly up-regulated in the PTU group, and rh2 associated with phototransduction was significantly down-regulated. By qRT-PCR, the expression levels of genes involved in carotenoid metabolism (scarb1, plin6, plin2, apoda, bco1, and rep65a), pteridine synthesis (gch2), and chromatophore differentiation (slc2a15b and csf1ra) were significantly higher at 36 hpf than at 24 hpf and 72 hpf, except for bco1. These gene expression profiles were consistent with the developmental changes of erythrophores. These findings provide insights into pigment cell differentiation and gene function in the regulation of red coloration and contribute to selective breeding programs for ornamental aquatic animals.

Effect of Temperatures on Cyclic Fatigue Resistance of 3 Different Ni-Ti Alloy Files

The aim of this study was to investigate and compare the effect of temperature on the cyclic fatigue resistance of conventional (ProTaper Universal [PTU]), Gold-Wire (ProTaper Gold [PTG]), and Fire-Wire (EdgeTaper Platinum [ETP]) nickel-titanium alloy files. Twenty files from each system were tested for cyclic fatigue resistance in an artificial canal model. The experiments were performed at room temperature and body temperature in controlled temperature water. Magnified videos were recorded using a dental operating microscope integrated camera during testing to detect file fracture. The number of cycles to failure (NCF) was calculated. The type of failure was investigated macroscopically and microscopically with a dental operating microscope and scanning electron microscope, respectively. The NCF at room temperature was significantly higher compared with body temperature in each system (P < .001). Compared at the same temperature, the ETP group demonstrated the highest NCF, followed by the PTG and PTU groups (P < .001). All files demonstrated cyclic fatigue failure macroscopically and microscopically. The 3 alloy files were affected by temperature. The cyclic fatigue resistance was reduced at the higher temperature and increased at the lower temperature. If the files are geometrically identical, files made of Fire-Wire are preferred compared with Gold-Wire and conventional nickel-titanium alloys based on cyclic fatigue resistance.

Incidence of and Risk Factors for Neonatal Hypothyroidism Among Women with Graves' Disease Treated with Antithyroid Drugs Until Delivery.

Background: The incidence of neonatal hypothyroidism among newborns born to mothers with Graves' disease (GD) who continued antithyroid drug (ATD) treatment until delivery has never been reported. Objective: Our primary objective was to investigate the incidence of neonatal hypothyroidism among newborns born to mothers with GD who were treated with ATD until delivery. Our secondary objective was to identify the cutoff ATD daily doses for neonatal hypothyroidism risk, based on maternal thyrotropin (TSH) receptor antibody (TRAb) levels. Methods: We conducted a retrospective cohort study. We included 305 pregnant women with GD who were treated with an ATD until delivery (63 treated with methimazole [MMI] and 242 treated with propylthiouracil [PTU]). Umbilical cord TSH, free thyroxine (fT4), and TRAb levels were measured at delivery, and we investigated the respective relationships between neonatal hypothyroidism at delivery and maternal fT4 levels, TRAb levels, and daily ATD doses during pregnancy. Neonatal hypothyroidism was diagnosed when the umbilical cord fT4 level was below the lower limit of the reference range. Results: The incidence of neonatal hypothyroidism at delivery was 19.0% ([confidence interval, CI, 11.2-30.4]; 12/63) in the MMI group and 12.8% ([CI, 9.2-17.6]; 31/242) in the PTU group. Neonatal goiter was observed in one neonate in the PTU group, and two infants in the PTU group required levothyroxine treatment. The daily ATD dose in the third trimester was the strongest predictor of neonatal hypothyroidism at delivery; the cutoff MMI dose was 10 mg/day, and the cutoff PTU dose was 150 mg/day. When the maternal TRAb level in the third trimester was above three times the upper limit of the normal range, the cutoff MMI dose was 20 mg/day, and the cutoff PTU dose was 150 mg/day. Conclusions: Maternal fT4 and TRAb levels were higher in the neonatal hypothyroid group, which suggested prolonged GD activity. Careful follow-up is necessary when maternal GD remains active and the ATD dose to control maternal thyrotoxicosis cannot be reduced.

Prenatal hypothyroidism diminished exogenous NO-mediated diastolic effects in fetal rat thoracic aorta smooth muscle via increased oxidative stress

Maternal hypothyroidism is an important problem of modern healthcare and is reported to increase the risk of cardiovascular diseases in the offspring later in life. However, it is unclear whether hypothyroidism during pregnancy causes vascular damage in the fetal period. We established the prenatal hypothyroidism rat model and collected the fetuses at the 21th day of gestation (GD21). Thyroid hormone concentrations in maternal and offspring blood serum were assessed by enzyme-linked immunosorbent assay (ELISA). The thoracic aortas of the fetuses were isolated for microvessel functional testing and histochemical stainings. qPCR and Western blot were performed to access mRNA and protein expression. We found that the concentrations of thyroid hormones in the serum of pregnant rats and fetuses were significantly suppressed at GD21. The responses of the fetal thoracic aortas to SNP were significantly attenuated in the PTU group. However, no statistical difference was found between the two groups when treated with either inhibitor (ODQ) or activator (BAY58–2667) of sGC. The production of O2−• in the arterial wall was significantly increased in hypothyroid fetuses. Moreover, the level of NADPH oxidase (NOX) was increased, while superoxide dismutase 2 (SOD2) was down-regulated in the PTU group, ultimately contributing to the increased production of superoxide. Additionally, decreased SNP-mediated vasodilation found in fetal vessels was improved by either NOX inhibitor (Apocynin) or SOD mimic (Tempol). These results indicate that increased oxidative stress is probably the cause of the diminished diastolic effect of exogenous NO in the thoracic artery of prenatal hypothyroidism exposed fetuses.

Shaping Ability of Reciprocating and Rotary Systems After Root Canal Retreatment: a CBCT Study.

The purpose of this in vitro study was to evaluate the shaping ability of reciprocating and continuous rotary systems after root canal retreatment. After preparation and root canal filling, mesial canals of 54 mandibular molars were distributed into 3 groups (n=18), according to the filling material removal and re-instrumentation protocols: WOG group - WaveOne Gold system; PTN group - ProTaper Next system; and PTU group - ProTaper Universal system. Cone-beam computed tomographic (CBCT) images acquisition of the mesial root canals was performed at different moments: (1) before instrumentation (unprepared root canals), (2) after preparation and filling, (3) after filling material removal and (4) re-instrumentation. The apical transportation (AT), centering ability (CA) and change in root canal diameter were assessed by CBCT analysis. The remaining filling material quantification was performed by radiographic examination. The statistical analyses were performed using the 3-way ANOVA, Tukey-Kramer, Kruskal-Wallis and Dunn multiple Comparison tests (p<0.05). The tested instruments did not show full CA (=1.0). PTN group had greater AT at the 5th mm in comparison with the WOG group (p<0.05). After re-instrumentation, WOG group had greater root canal diameter change at the 1st and 5th mm than PTN and PTU groups (p<0.05). There was no significant difference among groups when comparing the amount of remaining filling material after re-instrumentation (p>0.05). The tested systems provided minimal alteration in root canal morphology at the apical portion after root canal retreatment. However, WOG promoted greater change in root canal diameter.

Effect of 6-n-propyl-2-thiouracil or dexamethasone administration on the responses of antimicrobial components in goat milk to intramammary lipopolysaccharide infusion.

Heat stress impacts the immune system of dairy animals by altering the hypothalamic-pituitary-adrenal axis and thyroid function, leading to conditions such as hypothyroidism and hypercortisolism. This study aimed to elucidate the effect of hypothyroidism and hypercortisolism on the response of mammary innate immune function to inflammation caused by Escherichia coli in dairy goats. To induce hypothyroidism and hypercortisolism, we administered 6-n-propyl-2-thiouracil (PTU; for 21 days) and dexamethasone (DEX; for 5days), respectively, to six goats each; six goats without treatment were used as the control group. After treatment, lipopolysaccharide (LPS) from E. coli O111 was infused into the mammary gland. Somatic cell counts (SCC) and levels of lactoferrin (LF), S100A7, immunoglobulin A (IgA), and interleukin-8 (IL-8) in milk until 7days after LPS infusion were measured. An increase in SCC after LPS infusion was inhibited in both PTU and DEX groups, and an increase in LF after LPS infusion was inhibited in PTU group, compared with that in the control group. The results of the present study suggest that the recruitment of neutrophils and LF production decreased under hypothyroidism or hypercortisolism, which may be one of the causes underlying increased incidence of mastitis in dairy animals under heat stress conditions.

Region-specific effects of antenatal/early postnatal hypothyroidism on endothelial NO-pathway activity in systemic circulation.

BackgroundAntenatal/early postnatal hypothyroidism weakens NO-mediated anticontractile influence of endothelium in coronary arteries of adult rats, but it remains unclear whether this occurs in other vascular regions. We hypothesized that developmental thyroid deficiency is followed by region-specific changes in the endothelial NO-pathway activity in systemic vasculature. To explore this, we estimated the effects of antenatal/early postnatal hypothyroidism on NO-pathway activity and its potential local control mechanisms in rat mesenteric and skeletal muscle (sural) arteries.MethodsDams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%) during pregnancy and 2 weeks postpartum; control (CON) females received PTU-free water. Adult offspring (10–12-weeks) arteries were studied by wire myography, qPCR, and Western blotting.ResultsEndothelium removal or inhibition of NO-synthase with L-NNA augmented contractile responses to α1-adrenoceptor agonist methoxamine. In PTU compared to CON group, these effects were stronger in sural arteries, but did not differ in mesenteric arteries. The responses of both arteries to NO-donor DEA/NO were similar in CON and PTU rats. mRNA contents of deiodinase 2 and thyroid hormone receptor α were similar in mesenteric arteries of two groups but were elevated in sural arteries of PTU group compared to CON. The abundance of eNOS protein was higher in sural arteries of PTU compared to CON rats.ConclusionAntenatal/early postnatal hypothyroidism is followed by an increase in NO-mediated anticontractile influence in sural, but not in mesenteric arteries of adult animals. The diversity of hypothyroidism effects may be due to different alterations of local T3 synthesis/reception in different vascular beds.

Apical Transportation and Centering Ability After Root Canal Filling Removal Using Reciprocating and Continuous Rotary Systems: A CBCT Study.

Objective To evaluate the apical transportation and centering ability promoted by reciprocating and continuous rotary systems after root canal filling removal. Materials and Methods After obturation, 40 mesial root canals of mandibular molars were distributed into four groups ( n = 20) for filling material removal: PTU group–F2 instrument (25.08) of ProTaper Universal system; R25 group–R25 instrument (25.08) of Reciproc system; X2 group–X2 instrument (25.06) of ProTaper Next system and X3 group–X2 instrument (25.06) of ProTaper Next system, followed by X3 instrument (30.07). Cone-beam computed tomographic analysis was performed before and after filling material removal for acquisition of apical images. Apical transportation (AT) and its direction, and centering ability (CA), were assessed using the equations AT = (X1–X2)–(Y1–Y2) and CA = (X1–X2/Y1–Y2 or Y1–Y2/X1–X2), respectively. Data were submitted to the nonparametric Kruskal–Wallis and Dunn multiple comparison tests ( p < 0.05) for statistical analysis. Results There was no statistically significant difference among groups for AT ( p > 0.05), with a tendency toward transportation in the distal direction. Also, there was no statistically significant difference among groups regarding CA ( p > 0.05). Conclusions The different systems, including ProTaper Next, caused AT within the acceptable clinical limit after filling removal. In addition, none of the tested systems presented adequate CA.

Aframomum melegueta prevents the ejaculatory complications of propylthiouracil-induced hypothyroidism in sexually experienced male rats: Evidence from intravaginal and fictive ejaculations

ObjectiveHypothyroidism has been claimed to generate sexual dysfunctions such as ejaculatory disorders. Aframomum melegueta is an aphrodisiac plant with pro-ejaculatory properties. We investigated the protective effects of aqueous extract (AE) and methanolic extract (ME) of A. melegueta on the ejaculatory function of hypothyroid male rats. MethodsForty sexually experienced male rats were partitioned into 8 groups (5 rats per group) and treated for 28 d as follows: Group 1, Control; Group 2, propylthiouracil (PTU, 10 mg/kg) + distilled water (DW, 10 mL/kg); Group 3, PTU + 5% Tween 80 (10 mL/kg); Group 4, PTU + bromocriptine (6 mg/kg); Group 5, PTU + AE (20 mg/kg); Group 6, PTU + AE (100 mg/kg); Group 7, PTU + ME (20 mg/kg), and Group 8, PTU + ME (100 mg/kg). On days 0, 7, 14 and 28 of treatment, each male rat was paired with primed receptive female for measurement of ejaculatory latency time (ELT) and post-ejaculatory interval (PEI) for 1.5 h. On day 29, each male rat was urethane-anesthetized and the spinal cord was transected. Thereafter, following urethral/penile stimulations and intravenous injection of dopamine, contractions of the bulbospongiosus muscles and the intraseminal pressure were registered. After these recordings, blood was collected through the catheterization of abdominal artery and plasma was used for thyroid-stimulating hormone (TSH), prolactin and testosterone assays. ResultsPTU-induced hypothyroidism was characterized by a significant elevation (P < 0.001) of plasmatic TSH and prolactin levels, but a decline (P < 0.001) in plasmatic testosterone, compared to untreated group. ELT, PEI, contractions of the bulbospongiosus muscles and the intraseminal pressure were also altered by PTU treatment. On the contrary, A. melegueta extracts elevated testosterone (AE, 100 mg/kg, P < 0.01; ME, 100 mg/kg, P < 0.05) and decreased prolactin (AE, 100 mg/kg, P < 0.05; ME, 20 mg/kg, P < 0.05) levels, compared to corresponding controls. With regard to DW + PTU group, prolactin concentration was lowered (P < 0.05) in rats administered with bromocriptine. Treatment with A. melegueta extracts significantly prevented the lengthening of ELT (P < 0.05) and PEI (P < 0.001). Hypothyroid state also altered the fictive ejaculation by increasing the latency and decreasing the number and frequency of bulbospongiosus muscle contractions. There was also a decrease in the intraseminal pressure. These alterations were significantly (P < 0.05) alleviated in plant extract-treated groups. ConclusionThis study highlighted the ejaculatory disturbance of hypothyroidism in male rats and its prevention with A. melegueta extracts.

Vitamin C improves liver and renal functions in hypothyroid rats by reducing tissue oxidative injury

Background: The effects of Vit C on liver and renal function and the tissues oxidative damage was investigated in hypothyroid rats. Materials and methods: The pregnant rats were divided into 5 groups (n=6): (1) Control; (2) Propylthiouracil (PTU; 0.005%), (3-5) PTU plus 10, 100 or 500 mg/kg b.w. Vit C. The drugs were added to the drinking water of the dams and their pups during lactation period and then continued for the offspring through the first 8 weeks of their life. Finally, 7 male offspring from each group were randomly selected. Results: Thyroxine, protein and albumin concentrations in the serum and thiol content and superoxide dismutase (SOD) and catalase (CAT) activities in renal and liver tissues of hypothyroid group was lower (all P<0.001) while, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALK-P), creatinine and blood urea nitrogen (BUN) concentrations in the serum and malondialdehyde (MDA) in the liver and renal tissues were higher than the control (all P<0.001). All doses of Vit C increased thyroxine, protein and albumin and thiol content in in renal and liver tissues while, decreased AST, ALT and ALK-P concentration and MDA in liver and renal tissues compared to PTU group (P<0.05-P<0.001). Creatinine, BUN and SOD and CAT were improved by both 100 and 500 mg/kg of Vit C in the renal (P<0.05-P<0.001) and by 100mg/kg in the liver (P<0.05-P<0.001). Conclusion: Vit C improved liver and renal function of hypothyroid rats which might be due to its protective effects against tissues oxidative damage.

Antenatal/early postnatal hypothyroidism increases the contribution of Rho-kinase to contractile responses of mesenteric and skeletal muscle arteries in adult rats.

Maternal thyroid deficiency can increase Rho-kinase procontractile influence in arteries of 2-week-old progeny. Here we hypothesized that augmented role of Rho-kinase persists in arteries from adult progeny of hypothyroid rats. Dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%) during pregnancy and 2 weeks postpartum; control (CON) females received PTU-free water. At the age of 10-12-weeks, serum T3/T4 levels did not differ between PTU and CON male offspring. Cutaneous (saphenous), mesenteric, and skeletal muscle (sural) arteries were studied by wire myography, qPCR, and Western blotting. Saphenous arteries of PTU and CON groups showed similar responses to α1-adrenoceptor agonist methoxamine and were equally suppressed by Rho-kinase inhibitor Y27632. Responses of mesenteric arteries also did not differ between PTU and CON, but the effects of Y27632 were more prominent in the PTU group. Sural arteries of PTU rats compared to CON demonstrated augmented responses to methoxamine, increased RhoA mRNA contents and higher levels of MYPT1 phosphorylation at Thr855. Intergroup differences in contractile responses and phospho-MYPT1-Thr855 were eliminated by Y27632. Rho-kinase contribution to contractile responses of mesenteric and especially sural arteries is augmented in adult PTU rats. Therefore, maternal thyroid deficiency may have long-term detrimental consequences for vasculature in adult offspring.

Role of levothyroxine and vitamin E supplementation in the treatment of oxidative stress-induced injury and apoptosis of myocardial cells in hypothyroid rats.

To explore the underlying mechanism and treatment of myocardial injury caused by hypothyroidism, we evaluated oxidative stress in serum and myocardial tissue of hypothyroid rats. The effect of levothyroxine (LT4) replacement therapy and vitamin E (VitE) supplementation on oxidative stress-induced injury and apoptosis of myocardial tissue is examined. Male Sprague-Dawley rats were divided into five groups: normal control group, propylthiouracil group (PTU group), LT4 treatment group (PTU + LT4 group), vitamin E treatment group (PTU + VitE group), and combined treatment group (PTU + LT4 + VitE group). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) expression in serum and myocardium were determined. Myocardial apoptosis index (AI) in each group was determined by TUNEL assay. SOD levels in serum were significantly increased in PTU + VitE and PTU + LT4 + Vit E groups, as compared to that in PTU and PTU + LT4 groups (P < 0.05). MDA levels in serum and myocardial tissue were significantly lower in PTU + LT4, PTU + VitE, and PTU + LT4 + VitE groups, as compared to that in the PTU group (P < 0.05). Myocardial apoptosis was significantly increased in PTU and PTU + VitE groups as compared to that in the normal control group (P < 0.05), while it was significantly lower in PTU + LT4 and PTU + LT4 + VitE groups, as compared to that in the PTU group (P < 0.05). In this study, levothyroxine replacement therapy and vitamin E supplementation appeared to ameliorate myocardial apoptosis in hypothyroid rats, the mechanism of which appears to be related to improved thyroid function and reduced oxidative stress.

Analysis of Surface Characteristics of ProTaper Universal and ProTaper Next Instruments by Scanning Electron Microscopy.

BackgroundMany new rotary files systems have been introduced, however, limited research has been conducted related to the surface irregularities of these files and if these have any effects on the files themselves. Hence, the aim of the present study was to analyze surface irregularities of the ProTaper® Universal rotary files (PTU) and the ProTaper Next™ rotary files (PTN) before and after instrumentation in curved canals. The main objective was to investigate the nature of these irregularities and how they might influence the use and fracture of rotary files during root-canal treatments.Material and MethodsThe files were examined pre-operatively using a stereomicroscope and scanning electron microscopy(SEM) to analyze surface imperfections and the presence of particles. Mesial roots of forty extracted mandibular molars were selected. Each instrument was used to prepare one of the mesial canals. The files were then rinsed with alcohol, and autoclaved and analyzed again.ResultsOf the 80 files used in this study, five files fractured, five files unwound and seven files were curved or bent and they all belonged to the PTU group. Irregularities and debris could be visualized with the SEM on both unused PTU and PTN files. Most of the debris was found associated with deeper milling grooves and defects on the surface of the metal. Surface analysis of the files that were used and sterilized were performed and the SEM images demonstrated organic debris, metal flash, and crack formation and initiation of fractures for both file types. All files showed machining grooves, metal flash, debris, and defects on cutting edges.ConclusionsThese irregularities appear to be critical in the accumulation of debris and initiation of fatigue and crack propagation within the NiTi alloy. The accumulation of debris could be a concern due to the potential exchange of organic debris between patients. Key words:ProTaper® Universal, ProTaper Next™, surface characteristics, SEM.

NO-mediated anticontractile effect of the endothelium is abolished in coronary arteries of adult rats with antenatal/early postnatal hypothyroidism

IntroductionThyroid hormones are essential for proper development of many systems and organs, including circulatory system. Thyroid deficiency during pregnancy may affect the cardiovascular function in children early on and later in adulthood. However, long-term effects of early thyroid deficiency are poorly understood. We hypothesized that antenatal/early postnatal hypothyroidism will influence anticontractile effect of NO in coronary arteries of adult rats. Design and methodsTo model antenatal/early postnatal hypothyroidism dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%, w/v) from the first day of pregnancy till 2 weeks after delivery. Control females were supplied with pure water. Their male offspring was grown up till the age of 10–12 weeks. Systolic blood pressure was measured using tail cuff method. Septal coronary arteries were isolated and studied in wire myograph. Blood serum thyroid hormones concentrations (ELISA) and NO metabolites level (Griess method) were evaluated. ResultsAt the age of 10–12 weeks thyroid hormones, TSH concentrations, NO metabolites and systolic blood pressure level didn't differ between groups. Arterial responses to acetylcholine and exogenous NO-donor DEA/NO were similar in control and PTU groups. Along with that, in control rats endothelium denudation strongly potentiated basal tone of arteries and their contractile responses to thromboxane A2 receptor agonist U46619. The effects of endothelium denudation were absent in PTU rats indicating that anticontractile effect of endothelium is abolished in their arteries. Further, NO-synthase inhibitor L-NNA (100 μM) caused significant elevation of basal tone and increased U46619-induced contraction of endothelium-intact arteries only in control rats, while had no effect in PTU group. ConclusionsOur data demonstrate that NO-mediated anticontractile effect of endothelium is eliminated in coronary arteries of adult rats, which suffered from antenatal/early postnatal hypothyroidism. Therefore, maternal thyroid hormones deficiency may have detrimental consequences in adult offspring including coronary circulation pathologies, despite normal blood levels of thyroid hormones.

Influence of Instruments Used in Root Canal Preparation on Amount of Apically Extruded Debris.

The aim of the present study was to compare the effects of ProTaper Gold, WaveOne Gold, ProTaper Universal, and WaveOne instruments on the amount of apically extruded debris. Eighty mandibular premolar teeth with straight root canals were selected and assigned to four groups (n = 20). The root canals were instrumented using ProTaper Gold, WaveOne Gold, ProTaper Universal, and WaveOne systems. Eppendorf tubes containing apically extruded debris were weighed three times, and mean values were calculated. The net mass of the extruded debris was calculated by subtracting the initial mass from the final mass. The groups were compared using one-way analysis of variance and Tukey's post hoc tests at a significance level of P < 0.05. The PTG group extruded less debris than the PTU group, and the WOG group extruded less debris than the WO group (P < 0.05). All the instrumentation systems tested in the present study were associated with apical extrusion of debris.

Comparison of canal transportation in simulated curved canals prepared with ProTaper Universal and ProTaper Gold systems.

ObjectivesThe purpose of this study was to assess the ability of ProTaper Gold (PTG, Dentsply Maillefer) in maintaining the original profile of root canal anatomy. For that, ProTaper Universal (PTU, Dentsply Maillefer) was used as reference techniques for comparison.Materials and MethodsTwenty simulated curved canals manufactured in clear resin blocks were randomly assigned to 2 groups (n = 10) according to the system used for canal instrumentation: PTU and PTG groups, upto F2 files (25/0.08). Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open source program (FIJI). Evaluation of canal transportation was obtained for two independent canal regions: straight and curved levels. Student's t test was used with a cut-off for significance set at α = 5%.ResultsInstrumentation systems significantly influenced canal transportation (p < 0.0001). A significant interaction between instrumentation system and root canal level (p < 0.0001) was found. PTU and PTG systems produced similar canal transportation at the straight part, while PTG system resulted in lower canal transportation than PTU system at the curved part. Canal transportation was higher at the curved canal portion (p < 0.0001).ConclusionsPTG system produced overall less canal transportation in the curved portion when compared to PTU system.

Evaluation of the Shaping Characteristics of ProTaper Gold, ProTaper NEXT, and ProTaper Universal in Curved Canals

IntroductionThis study evaluated the shaping characteristics of the ProTaper Gold system (PTG; Dentsply Maillefer, Ballaigues, Switzerland) and compared it with that of the ProTaper Next (PTN, Dentsply Maillefer) and ProTaper Universal (PTU, Dentsply Maillefer) systems using micro–computed tomographic imaging. MethodsTwenty-four mandibular first molars with 2 separate mesial canals were matched anatomically using micro–computed tomographic scanning (SkyScan1174v2; Bruker-microCT, Kontich, Belgium) with a voxel size of 19.6 μm. Canals were prepared with PTG, PTU, or PTN rotary systems to F2 or X2 instruments, respectively, and scanned again. Coregistered images were evaluated for 2- and 3-dimensional morphometric measurements of canal transportation, centering ability, untouched canal walls, and remaining dentin thickness. Data were statistically compared using Kruskal-Wallis and 1-way analysis of variance tests (α = 5%). ResultsOverall, PTN showed significantly higher percentage values of static voxels than PTG and PTU systems (P < .05). Surface area, perimeter, and minor diameter were higher in the PTG and PTU groups than in the PTN group (P < .05). No difference was observed in form factor, roundness, major diameter, aspect ratio, or structure model index (P > .05). PTG (0.11 ± 0.05 mm) and PTN (0.09 ± 0.05 mm) produced significantly less transportation than PTU (0.14 ± 0.07 mm) (P < .05), and the percentage decrease in dentin thickness was significantly lower for PTG (22.67 ± 2.96) and PTN (17.71 ± 5.93%) (P ≥ .05) than PTU (29.93 ± 6.24%) (P < .05). ConclusionsPTG and PTN produced less transportation and maintained more dentin than PTU. PTN had less canal wall contact than PTG and PTU, but all file systems were able to instrument moderately curved mesial root canals of mandibular molars without clinically significant errors.

Hypothyroidism and its rapid correction alter cardiac remodeling.

The cardiovascular effects of mild and overt thyroid disease include a vast array of pathological changes. As well, thyroid replacement therapy has been suggested for preserving cardiac function. However, the influence of thyroid hormones on cardiac remodeling has not been thoroughly investigated at the molecular and cellular levels. The purpose of this paper is to study the effect of hypothyroidism and thyroid replacement therapy on cardiac alterations. Thirty Wistar rats were divided into 2 groups: a control (n = 10) group and a group treated with 6-propyl-2-thiouracil (PTU) (n = 20) to induce hypothyroidism. Ten of the 20 rats in the PTU group were then treated with L-thyroxine to quickly re-establish euthyroidism. The serum levels of inflammatory markers, such as C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL6) and pro-fibrotic transforming growth factor beta 1 (TGF-β1), were significantly increased in hypothyroid rats; elevations in cardiac stress markers, brain natriuretic peptide (BNP) and cardiac troponin T (cTnT) were also noted. The expressions of cardiac remodeling genes were induced in hypothyroid rats in parallel with the development of fibrosis, and a decline in cardiac function with chamber dilation was measured by echocardiography. Rapidly reversing the hypothyroidism and restoring the euthyroid state improved cardiac function with a decrease in the levels of cardiac remodeling markers. However, this change further increased the levels of inflammatory and fibrotic markers in the plasma and heart and led to myocardial cellular infiltration. In conclusion, we showed that hypothyroidism is related to cardiac function decline, fibrosis and inflammation; most importantly, the rapid correction of hypothyroidism led to cardiac injuries. Our results might offer new insights for the management of hypothyroidism-induced heart disease.

Dose-dependent effects of perinatal hypothyroidism on postnatal testicular development in rat offspring.

The role of thyroid hormones in gonad development remains incompletely understood. We examined the dose-related effects of perinatal hypothyroidism induced by a reversible goitrogen, 6-propyl-2-thiouracil (PTU), on reproductive development in male rat offspring. Timed-pregnant Sprague-Dawley rats were orally administered PTU (0, 0.5, 1.0, or 2.0 mg/kg/day) by gavage from gestational day 15 through postnatal day 20. We observed a significant dose-dependent decrease in body weight in offspring with PTU exposure up to 13 weeks of age, but body weight became comparable among groups by 26 weeks of age. Testicular weight tended to be lower up to 7 weeks but was higher after 13 weeks of age. Epididymis weight was not different among the groups at any age. Plasma concentrations of thyroxine and triiodothyronine in the PTU groups were significantly lower at 3 weeks of age but recovered to normal levels by 26 weeks of age. No dose-related trend in plasma testosterone concentrations was found. Seminiferous tubules were larger at 13 and 26 weeks of age with PTU exposure. The number of Sertoli cells was significantly higher from 3 through 26 weeks of age. The number of Leydig cells was significantly lower up to 7 weeks of age but was comparable among groups from 13 weeks of age onwards. Thus, transient gestational and lactational thyroid hormone suppression induced small testes in early life but led to paradoxical dose-dependent testicular enlargement in adults as indicated partly by larger seminiferous tubules with numerous Sertoli cells in male rat offspring.