Heat Treatment Group Research Articles

Effects of zinc sulfate pretreatment on heat tolerance of Bama miniature pig under high ambient temperature.

The aim of this study was to evaluate the heat tolerance of Bama miniature pigs under high ambient temperature (40°C) and Zn interactive functions during heat treatment (HT). Bama miniature pigs (male; n = 24; 6-mo old; BW = 10.79 ± 0.06 kg) were randomly allotted to 4 groups and were fed a basal diet or the basal diet supplemented with 1,500 mg of Zn (ZnSO4·H2O)/kg diet for 38 d. At 7 mo of age (d 30), the thermal neutral (TN) groups remained at 25°C, whereas the HT groups were exposed to ambient temperature at 40°C for 5 h daily for 8 consecutive days. Pigs in 4 groups were sacrificed on d 38. Individual rectal temperatures, skin temperatures, and breathing rates were recorded at 3 h after the onset of HT and the blood samples were collected immediately after HT on d 30, 34, and 38. Pigs fed diets with or without Zn doubled their breathing rates (P < 0.05) and increased body surface, scrotal, and rectal temperatures during HT on d 30, 34, and 38, respectively. Zinc supplementation increased BW gain (BWG; P < 0.05) during 38-d experiment period, and HT decreased BWG only from d 30 to 34 (P < 0.05). Heat treatment increased serum testosterone on d 30 (P < 0.05). Zinc supplementation decreased the heat-induced increase of testosterone in HT on d 30 and 34 (P < 0.05). The relative weight of liver increased in HT groups (P < 0.05). Zinc supplementation decreased the relative weights of spleen (P < 0.05) and testis (P < 0.01). The values of abnormal lymphocyte count and large unstained cell count declined approximately 5 times in groups of Zn supplementation, whereas Zn supplementation increased the values of red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin. Zinc concentrations increased in serum, liver, kidney, epididymis, longissimus, hair, and feces in groups fed with Zn (P < 0.01). However, additional Zn decreased Zn concentrations in lung, spleen, and testis (P < 0.01). Moreover, HT decreased serum Zn concentrations (P < 0.01). In conclusion, Zn supplementation could be used to alleviate the decline of serum Zn during periods of high ambient temperatures. However, pretreated supplementation with pharmacological Zn did not promote heat tolerance but impacted the erythropoiesis, immunity, and reproductive organ development in Bama miniature pigs.

Quality Characteristics of Sweet-pumpkin Paste with Different Thermal Condition and Sweet-Pumpkin Latte with Various Gums

Abstract For the production of pumpkin paste with respect to heating conditions, we steamed the pumpkin for roughly 15 min, heated it wi th high pressure treatment for 0 min (A), 10 min (B), 20 min (C), 40 min (D), and subsequently investigated the quality characteristics. Generally a significant difference was observed between the pumpkin paste treated with and without high-pressure heat. The values of water content, crude protein and crude fiber of the high-pressure heat-treated groups B, C, D were decreased compared with untreated group A. The soluble fiber in experimental group B sweet-pumpkin paste treated with high-pressure heat for 20 min was higher th an the control, and the highest value at 2.02. Experimental group D sweet-pumpkin paste treated with high-pressure heat for 40 min was found to have a decreased soluble fiber content relative to the control. The L value for the color of the group A untreated control sweet-pumpkin paste (no high-pressure heating) decreased as the time increased from 10 min to 40 min, with L values of 50.33, 49.46, and 48.06, respectively. The b value for the color of the sweet-pumpkin paste also decreased, showing a significant difference. Taking into account all the results, we chose experimental group B in order to prepare sweet-pumpkin latte. We used 0.2% gum (xanthan gum, locust bean gum, guar gum) as a stabilizer. Sweet-pumpkin latte with xanthan and locust bean gum has a suspension stability eff ect that lasts 90 min. The L and b values of sweet-pumpkin latte with gums increase and a value decrease compared with the control. In t erms of the overall acceptance of the sweet-pumpkin latte, the experimental group with xanthan gum scored the best.Key words: sweet-pumpkin, paste, sweet-pumpkin latte

Effect of feeding heat-treated colostrum on risk for infection with Mycobacterium avium ssp. paratuberculosis, milk production, and longevity in Holstein dairy cows

In summer 2007, a randomized controlled field trial was initiated on 6 large Midwest commercial dairy farms to investigate the effect of feeding heat-treated (HT) colostrum on transmission of Mycobacterium avium ssp. paratuberculosis (MAP) and on future milk production and longevity within the herd. On each farm, colostrum was collected daily from fresh cows, pooled, divided into 2 aliquots, and then 1 aliquot was heat-treated in a commercial batch pasteurizer at 60°C for 60min. A sample from each batch of colostrum was collected for PCR testing (MAP-positive vs. MAP-negative). Newborn heifer calves were removed from the dam within 30 to 60min of birth and systematically assigned to be fed 3.8 L of either fresh (FR; n=434) or heat-treated (HT; n=490) colostrum within 2h of birth. After reaching adulthood (>2 yr old), study animals were tested once annually for 3 yr (2010, 2011, 2012) for infection with MAP using serum ELISA and fecal culture. Lactation records describing milk production data and death or culling events were collected during the 3-yr testing period. Multivariable model logistic and linear regression was used to investigate the effect of feeding HT colostrum on risk for testing positive to MAP during the 3-yr testing period (positive/negative; logistic regression) and on first and second lactation milk yield (kg/cow; linear regression), respectively. Cox proportional hazards regression was used to investigate the effect of feeding HT colostrum on risk and time to removal from the herd. Fifteen percent of all study animals were fed PCR-positive colostrum. By the end of the 3-yr testing period, no difference was noted in the proportion of animals testing positive for MAP, with either serum ELISA or fecal culture, when comparing the HT group (10.5%) versus the FR group (8.1%). There was no effect of treatment on first- (HT=11.797kg; FR=11,671kg) or second-lactation (HT=11,013kg; FR=11,235kg) milk production. The proportion of cows leaving the herd by study conclusion was not different for animals originally fed HT (68.0%) versus FR (71.7%) colostrum. Although a previous study showed that feeding HT colostrum (60°C for 60min) produces short-term benefits, including improved passive transfer of IgG and reduced morbidity in the preweaning period, the current study found no benefit of feeding HT colostrum on long-term outcomes including risk for transmission of Mycobacterium avium ssp. paratuberculosis, milk production in the first and second lactation, and longevity within the herd.

Zinc might prevent heat-induced hepatic injury by activating the Nrf2-antioxidant in mice.

Zinc (Zn) is generally known to be an essential trace element with growth-promoting and antioxidant activities. The present study was performed to clarify the role of Zn in the livers of heat-treated mice. Eight-week-old male mice were divided into control (Con), heat treatment (HT) and heat treatment plus zinc groups (HT + Zn) and were fed diets containing 60, 60, or 300 mg/kg Zn (zinc sulfate), respectively. After 30 days of feeding on their respective diets, the control group was maintained at a controlled temperature (25 °C), whereas the HT and HT + Zn groups were exposed to an elevated ambient temperature (40-42 °C) for 2 h each day. After heat exposure for seven consecutive days, sera and liver tissues were collected. The mice in the HT group exhibited reduced liver weights and lower hepatosomatic indices. Histological findings revealed that the hepatocytes of the HT group were subjected to serious damage and exhibited irregular arrangements and nuclear pyknosis. Moreover, in the HT group, the hepatic malondialdehyde levels were significantly increased, while the serum alkaline phosphatase levels, hepatic copper/zinc-superoxide dismutase (CuZn-SOD) and glutathione peroxidase activities were significantly reduced compared to those of the control group. However, in the HT + Zn group, the histomorphology of the liver was restored, the serum aspartate aminotransferase (AST) level was significantly decreased, and the hepatic CuZn-SOD activity was significantly increased compared to the HT group. Furthermore, expressions of the hepatic Nrf2 protein and Nrf2, Keap1, and NQO1 genes in the HT + Zn group were not only higher than the HT group but also higher than the control group. Zn might alleviate heat-induced hepatic injury as revealed by restored histomorphology and AST level. Our results further suggest that Zn might exert its protective effects via the activation of the Nrf2-antioxidant pathway.

Effect of surface and heat treatments on the biaxial flexural strength and phase transformation of a Y-TZP ceramic.

To evaluate the effect of grinding and airborne-particle abrasion on the biaxial flexural strength (BFS) and phase transformation of a Y-TZP ceramic, and examine whether sintering the veneering porcelain renders the previous heat treatment recommended by the manufacturer unnecessary. Lava zirconia specimens (N = 108) were obtained with the following dimensions: 14.0 mm diameter × 1.3 mm thickness (n = 36) and 14.0 mm × 1.6 mm (n = 72). The thicker specimens were ground with diamond burs under irrigation and received (heat-treated groups) or not (non-heat-treated groups) a heat treatment (1000°C for 30 min) prior to the four firing cycles applied to simulate the sintering of the veneering porcelain. All specimens were air abraded as follows (n = 12): 1) 30-μm silica-modified Al₂O₃particles (Rocatec Soft); 2) 110-μm silica-modified Al₂O₃particles (Rocatec Plus); and 3) 120-μm Al₂O₃particles, followed by Rocatec Plus. Three specimens of each group were analyzed by x-ray diffraction (XRD) to assess the monoclinic phase content (%). The BFS test was performed in a mechanical testing machine (Instron 8874). Data (MPa) were analyzed by two-way ANOVA (grinding × airborne-particle abrasion and heat treatment × airborne-particle abrasion) and Tukey's post-hoc test (α = 0.05). The strength reliability was analyzed using the Weibull distribution. Grinding significantly decreased the BFS of the non-heat-treated groups (p < 0.01). Within the ground groups, the previous heat treatment did not influence the BFS (p > 0.05). Air abrasion only influenced the BFS of the ground/heat-treated groups (p < 0.01). For the non-heat-treated groups, the grinding did not decrease the Weibull modulus (m), but it did decrease the characteristic strength (σ0). For Rocatec Soft and 120-μm Al₂O₃particles + Rocatec Plus, the heat-treated groups presented lower m and higher σ0 than the ground/non-heat-treated groups. The independent variables did not seem to influence phase transformation. Air-abraded surfaces presented higher monoclinic zirconia content than the as-sintered and ground surfaces, which exhibited similar content. Even under irrigation, grinding compromised the Y-TZP ceramic strength. The sintering of the veneering porcelain rendered the previous heat treatment recommended by the manufacturer unnecessary. Airborneparticle abrasion influenced the strength of heat-treated zirconia.

Effects of whole-body heat on male germ cell development and sperm motility in the laboratory mouse.

This study investigated the effects of high temperatures on male germ cell development and epididymal sperm motility of laboratory mice. In Experiment 1, adult males (n=16) were exposed to whole-body heat of 37-38°C for 8h day(-1) for 3 consecutive days, whereas controls (n=4) were left at 23-24°C. In Experiment 2, adult mice (n=6) were exposed to 37-38°C for a single 8-h period with controls (n=6) left at 23-24°C. Experiment 2 was conducted as a continuation of previous study that showed changes in spermatozoa 16h after exposure to heat of 37-38°C for 8h day(-1) for 3 consecutive days. In the present study, in Experiment 1, high temperature reduced testes weights 16h and 14 days after exposure, whereas by Day 21 testes weights were similar to those in the control group (P=0.18). At 16h, 7 and 14 days after exposure, an increase in germ cell apoptosis was noticeable in early and late stages (I-VI and XI-XII) of the cycle of the seminiferous epithelium. However, apoptosis in intermediate stages (VII-X) was evident 16h after heat exposure (P<0.05), without any change at other time periods. By 21 days, there were no significant differences between heat-treated groups and controls. Considerably more caspase-3-positive germ cells occurred in heat-treated mice 16h after heat exposure compared with the control group (P<0.0001), whereas 8h after heat in Experiment 2, sperm motility was reduced with a higher percentage of spermatozoa showing membrane damage. In conclusion, the present study shows that whole-body heat of 37-38°C induces stage-specific germ cell apoptosis and membrane changes in spermatozoa; this may result in reduced fertility at particular times of exposure after heating.

Histopathological changes by the use of soft reline materials: a rat model study.

AimTo assess the histopathological changes of rat palatal mucosa exposed to soft reline materials.MethodsForty-five adult female Wistar rats with controlled living conditions and fed ad libitum were employed. Palatal appliances of heat-polymerized acrylic resin Lucitone 550 were manufactured and worn by forty animals during 14 days. Five animals did not use the appliances (G1) and were used to control the appliance influence. One experimental group (n = 10) used the appliances without any relining material (G2) to control the material effect. Three experimental groups (n = 10) received the following soft reline materials below appliances: Dentusoft (G3), Dentuflex (G4), and Trusoft (G5). Appliances from half of each experimental group(n = 5) was immersed in water bath at 55°C for 10 min before use. Animals were slaughtered and the palates were fixed in 10% buffered formalin. Hematoxylin and eosin stained sections of 5 µm were analyzed by computerized planimetry. Cellular compartment, keratin and total epithelial thickness, and basement membrane length were measured to histopathological description.Analysis of variance and Tukey post-hoc test were used to data examination(α = 0.05).ResultsFor heat-treatment groups, G4 showed less elongated ridges at the basal layer interface (p = 0.037) than G2. When comparing the conditions with and without heat-treatment, only G2 showed a significant decrease in the cellular compartment, keratin layer and total epithelium thickness (p<0.05).ConclusionThe post-polymerization for Lucitone 550 was an effective method to reduce the changes in the rat palatal mucosa. The soft reline materials tested did not cause significant histopathological changes in the rat palatal mucosa.

Abstract B170: Non-lethal heat treatment of cells results in reduction in cancer stem cell fraction and metastatic potential.

Abstract Metastatic disease and recurrence have been hypothesized to result from residual cancer stem cells (CSCs), also referred to as tumor-initiating cells, which evade initial treatment. CSCs are thought to have the ability to recapitulate the heterogeneity of the parental tumor, to self-renew, and to maintain their self-renewing potential over long periods of time. Therapeutic targeting of the CSC population, in addition to differentiated malignant cells, may be critical for the successful treatment and elimination residual disease in human cancer. Hyperthermia has been used as an adjuvant treatment in which body tissue is exposed to high temperatures (up to 45 °C) in combination with radiation or chemotherapy. In this study, we test the hypothesis that a major effect of hyperthermia is to weaken or reduce the CSC population, resulting in reduced invasive metastatic potential. A pulmonary metastasis model was used, where tumor cells are administered to a mouse by i.v injection. 4 × 105 cells/mouse will yield between 50 and 250 pulmonary nodules visible on the lung surface. The tumor nodules can be easily visualized by bioluminescence imaging (BLI). For effects of hyperthermia on metastatic potential, a mouse melanoma (B16F10-Luc.) model was used. Thermal treatment consisted of immersing the cells in a heated water bath with temperature maintained for 25 min at 37 °C or 43 °C. After thermal treatment, viable control or heat treated (HT) cells were injected into the mice via tail vein and BLI used to determine the metastatic disease in the lungs. MDA-MB 231-Luc. breast cancer cells were administrated after HT. Primary tumor volume and lung metastasis were measured by BLI. For comparison, MM 231 and B16 cells were analyzed via FACS following the same regimen of sham or heat treating using the combination CD44+/CD133+ markers to separate and count the CSC population. In the control, metastatic disease resulted in a faintly observed signal in 3 days, and a clearly observed signal in 6 days from the lungs. In contrast, the HT group had no signal at either time point. HT cells similarly showed an initial loss of BLI signal due to denaturation of luciferase, however, this was completely recovered within 4 days. Overall viability was not significantly altered by HT. FACS analysis of the MM 231 cells showed a 52.2 % reduction in CD44 and 29.6 % reduction in CD133 expression compared to controls, from 55.2 % of the total to 26.4 % in CD44 and from 49.2 % of the total to 34.6 % in CD133. B16 cells showed a 32.1 % reduction in CD44 expression, but they showed similar CD133. Both B16 and MM 231 tumor model showed significant changes in tumor growth with HT. The tumor volume of HT group was smaller than control and metastatic disease was also significantly reduced in the HT. These results suggest that hyperthermia may be capable of selectively injuring CSCs thereby reducing the incidence of metastatic disease formation. However, hyperthermia has only minimal impact on overall cancer cell survival numbers, and, due to its limited application in time and space, has no effect on CSCs already seeded or in circulation unless whole-body treatment is possible. These facts may explain hyperthermia's limited clinical efficacy, but also point towards a strategy for leveraging CSC thermal sensitivity to improve outcomes as an adjuvant therapy. Further studies are needed to establish appropriate methods and timing of treatment. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B170. Citation Format: Yoo-Shin Kim, Tae Hoon Lee, Brian E. O'Neill. Non-lethal heat treatment of cells results in reduction in cancer stem cell fraction and metastatic potential. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B170.

Astaxanthin ameliorates heat stress-induced impairment of blastocyst development In Vitro: –astaxanthin colocalization with and action on mitochondria–

The effects of astaxanthin (Ax) on the in vitro development of bovine embryos cultured under heat stress were investigated in combination with the assessment of its cellular accumulation and action on mitochondrial membrane potential (ΔΨm). Bovine ≥8-cell embryos were collected on day 3 after in vitro fertilization and exposed to single (day 4) or repeated (day 4 and 5) heat stress (10 h/day at 40.5 °C). Ax was added into culture medium under the repeated heat stress and blastocyst development was evaluated. The cellular uptake of Ax in embryos was examined using bright-field and confocal laser-scanning microscopy, and high-performance liquid chromatography. The relationship between Ax and mitochondria localization was assessed using MitoTracker dye. The effects of Ax on ΔΨm were investigated using JC-1 dye. Blastocyst development in the repeated heat stress treatment decreased significantly (P < 0.05) compared with those in single heat stress or normal thermal treatment. The addition of Ax into culture medium did lead to a significant recovery in blastocyst development in the repeated heat-treated group. Ax was detected in cytoplasm of embryos and observed to colocalize with mitochondria. Ax recovered ΔΨm in embryos that was decreased by the heat treatment. Ax ameliorated the heat stress-induced impairment of blastocyst development. Our results suggest that the direct action of Ax on mitochondrial activity via cellular uptake is a mechanism of the ameliorating effects.

The influence of nano hydroxyapatite coating on osseointegration after extended healing periods

ObjectiveStudies observing early wound healing periods around dental implants demonstrate an implants ability to enhance osseointegration, the bone–implant interactions for extended healing periods though have not been thoroughly studied. MethodsTwenty threaded titanium alloy (Ti6Al4V, Grade 5) implants were inserted bilaterally, half prepared to impart stable hydroxyapatite nanoparticles onto a sand blasted and acid etched surface (HA) and half with a non-coated control surface with only heat treatment (HT), into eighteen rabbit femurs. At 12 weeks, the bone–implant blocks were retrieved for micro computed tomography (μCT), histologic processing and histomorphometric evaluation. ResultsThe bone-to-implant contact for the entire threaded portion of the implant revealed 57.1% (21.0) for the HT group and 38.8% (17.7) for the HA group with a total bone area within the threads 72.5% (13.9) (HT) and 59.7% (12.5) (HA). The 3D reconstructed μCT image corresponded to the histomorphometric results. SignificanceIt is suggested that multiple factors such as the change in topography and chemistry may have influenced the outcomes.

Soluble Sugar Content and Metabolism as Related to the Heat-Induced Chilling Tolerance of Loquat Fruit During Cold Storage

The effects of high-temperature, short-time hot air treatment (45 °C for 3 h) on soluble sugar metabolism and chilling tolerance in loquat fruit stored at 5 °C for 5 weeks were investigated. Heat treatment significantly reduced chilling severity, as evidenced by lower firmness and internal browning and higher levels of extractable juice. Meanwhile, this treatment accelerated the activities of acid invertase, neutral invertase, sucrose phosphate synthase and sucrose synthase during storage. However, sucrose degradation was predominant, which caused lower levels of sucrose and higher levels of glucose and fructose in the heat-treated group. In addition, the ascorbate acid content and the activities of ascorbate peroxidase and glutathione reductase in the heat-treated fruit were much higher than those in control fruit, resulting in lower levels of hydrogen peroxide (H2O2) and malondialdehyde and decreased membrane permeability as well as a higher unsaturated/saturated fatty acid ratio at the end of storage. Our results suggest that the increased levels of reducing sugars, especially those of glucose, may induce the ascorbate–glutathione cycle activity to scavenge for H2O2, whose content relates to the heat-induced chilling tolerance of loquat fruit.

Thermal stability of yeast hydrolysate as a novel anti-obesity material

We examined the thermal stability of yeast hydrolysates before and after ultrafiltration (UF) in vitro, and the anti-obesity activity of yeast hydrolysates before and after heat treatment in vivo. Yeast hydrolysate after UF showed significantly higher thermal stability than before UF. Yeast hydrolysates before and after UF showed 3 and 4 thermal transition peaks in their thermograms, respectively, and the total thermal denaturation enthalpies of yeast hydrolysates before and after UF were 69.5 and 36.5J/g, respectively. For the anti-obesity activity study, yeast hydrolysates before and after heating were administered ad libitum with water to 7-week-old male SD rats. The administration of yeast hydrolysate (YH-control; no heat treatment, YH-1; heat treatment at 140°C, and YH-2; heat treatment at 160°C) significantly increased mRNA expression of cocaine- and amphetamine-regulated transcript (CART) compared with control rats (saline administration). However, there was no significant difference between the heat-treated groups and YH-control and there was no significant difference in neuropeptide Y expression between the heat-treated groups and YH-control. These results suggest that yeast hydrolysate can be use an anti-obesity material after heat treatment.

Electroacupuncture enhances spermatogenesis in rats after scrotal heat treatment

Spermatogenesis is regulated by a cascade of steroid regulated genes in the testis. Recent studies suggested that acupuncture may improve fertility in men with abnormal semen parameters. Yet, the underlying mechanisms in which acupuncture enhances spermatogenesis remain largely unknown. Here we used a scrotal heat-treated rat model to study the effect of electroacupuncture (EA) on recovery of spermatogenesis. In this model, spermatogenesis was disrupted by 30 min scrotal heat treatment at 43°C. Ten sessions of EA were given at Baihui (GV20), Guanyuan (CV4), Zusanli (ST36) and Sanyinjiao (SP6) from day 9 to day 36 post-treatment. Sperm motility and production, morphology of the germinal epithelium by Johnsen’s scoring, germ cell apoptosis by TUNEL staining, proliferation by proliferating cell nuclear antigen (PCNA) staining, as well as serum testosterone and inhibin B levels by immunoassays were evaluated on day 0, 1, 9, 25, 37, 46, 56 and 79. When compared with the heat-treated (H) group, the heat-treated plus EA (H+EA) group showed a significant increase (p < 0.05) in PCNA-positive cells and inhibin B levels on days 37 and 46, and a higher Johnsen’s score till day 56. On day 79, motile spermatozoa could be found in the vas deferens of H+EA group only. Consistently, there was a trend of improved motility and increased number of motile epididymal spermatozoa in the H+EA group than the H group; while apoptosis of germ cells and serum testosterone levels were similar between the two groups. Taken together, EA enhanced germ cell proliferation through improvement of Sertoli cell functions. This may facilitate the recovery of spermatogenesis and may restore normal semen parameters in subfertile patients.

Hyperthermia induces upregulation of Connexin43 in the golden hamster neural tube

During early embryonic development, maternal exposure to hyperthermia induces neural tube defects (NTDs). Connexins are essential for the formation of gap junctions and Connexin43 (Cx43) is crucially involved in neural tube development. This study was designed to explore the potential role of Cx43 in NTDs induced by hyperthermia. Using PCR, the Cx43 cDNA was screened from the cDNA library of the neural tube from golden hamsters treated with hyperthermia. By Northern blot, the expression of Cx43 in heat-treated and control groups of the golden hamsters at day 8.5 after mating was detected. Finally, by in situ hybridization and RT-PCR, the expression of Cx43 was examined in the neural tube at different time points after heat treatment. Cx43 was stably expressed in heat-treated and control groups of the golden hamsters, whereas the expression was evidently higher in the heat-treated group. Cx43 expression in the neural tube at different time points after heat treatment was significantly higher than in control groups (p < 0.01). Hyperthermia did not induce any mutations in Cx43 cDNA. Our data provide the first evidence that hyperthermia induces upregulation of Cx43 in the golden hamster neural tube. NTDs caused by hyperthermia may be intimately related with the overexpression of Cx43.

Heat treatment of nickel-titanium rotary endodontic instruments: effects on bending properties and shaping abilities

To evaluate the bending properties and shaping abilities of nickel-titanium endodontic instruments processed by heat treatment. K3 files were heated for 30 min at 400 °C (group 400), 450 °C (group 450) and 500 °C (group 500). Files that were not heat treated served as controls. A cantilever-bending test was used to evaluate changes in specimen flexibility caused by heat treatment. Curved root canal models were prepared. The times required for preparation, deformation and fracture were recorded. Pre- and postoperative images were superimposed. The amounts of resin removed from both the inner and the outer sides of the curvature in the apical 6 mm were determined. In the cantilever-bending test, load values of the control group and group 500 were higher than those of groups 400 and 450 at the elastic range (P<0.05). At the superelastic range, the bending load of the control group was the highest amongst all groups (P<0.05). Regarding shaping ability, in the control group, root canals at the apex were transported more to the outer side of the curvature compared with those of all heat-treated groups (P<0.05). Root canals of group 400 at 3 mm from the apex were transported less compared with those of other groups (P<0.05). No significant difference was found in working time amongst the groups. In group 450, there was no plastic deformation or fracture of the file. Heat treatment of files might improve their flexibility, making them more effective for preparation of curved canals.

Effects of Astaxanthin‐containing Oil on Development and Stress‐related Gene Expression of Bovine Embryos Exposed to Heat Stress

Early bovine embryos are vulnerable to heat stress during the first few days after fertilization. The inhibitory effect of heat stress on embryonic development is known to be associated with oxidative stress, which can be attenuated by antioxidants. In the present study, we focused on the use of astaxanthin as an antioxidant and examined the effects of astaxanthin-containing oil (Ax) on post-fertilization development of bovine embryos subjected to heat stress in vitro and the expression of stress-related genes. Bovine 1-cell embryos were in vitro produced by in vitro maturation and fertilization (IVF) of oocytes recovered from abattoir-derived ovaries. At 20 h post-insemination (hpi, 0 h = the start of IVF), the embryos were introduced in modified synthetic oviduct fluid supplemented with 25 ppm of Ax (concentration of astaxanthin was 0.25 ppm) or vehicle (dimethyl sulfoxide) up to 72 hpi. The embryos were basically cultured at 38.5°C, and in the heat stress group, embryos were exposed twice to 40.5°C for 10 h (at 20-30 and 44-54 hpi). Under the condition without the Ax treatment, the cleavage rate, rate of development to the 5-8 cell stage, blastocyst yield from cultured embryos and that from cleaved embryos were lower in the heat stress group than in the group not subjected to heat stress (p < 0.05). In the heat stress group, the rate of development to the 5-8 cell stage was improved (p < 0.05) by the addition of Ax. Subsequently, we performed semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) to investigate the effects of heat stress and Ax on the mRNA expression of Src homology 2 domain-containing transforming protein C1 (SHC1), an oxidative stress adaptor protein, and superoxide dismutase 2 (SOD2), a mitochondrial reactive oxygen species (ROS) scavenger. In 5-8 cell embryos at 72 hpi, the mRNA expression levels of SHC1 and SOD2 were lower in the Ax- and heat-treated group than in the other groups (p < 0.05). These results suggest that Ax added to the culture medium ameliorates the embryonic development impaired by heat stress with its altering effects on the expression of stress-related genes.

Soleus Adaptation to Combined Exercise and Heat Acclimation

Adaptation to heat (acclimation [ACC]) and exercise training (EX) require global changes at all levels of body organization to enhance muscle performance. In this investigation, we combined these stressors and examined physiological and genomic aspects of adaptation in skeletal muscle (soleus). Rats were divided into four groups: C (controls), ACC--acclimated to heat only at 34 degrees C, EX--aerobic exercise on a treadmill at 24 degrees C, and EXAC--acclimated to combined heat and aerobic training. The ACC period was 30 d. Isometric force generation was measured using isolated muscle preparations stimulated at 1-100 Hz, allowing assessment of muscle endurance. Global genomic responses of homeostatic genes were detected using a complementary DNA (cDNA) Atlas array (Rat 1.2; Clontech Laboratory, Palo Alto, CA). Significantly elevated force generation (P < 0.05) was only found in the EXAC group along with a marked decrease in relaxation velocity. Both heat-treated groups (ACC and EXAC) demonstrated less of a drop in power at stimulation frequencies above the highest force generation (P < 0.05). Gene reprogramming was noted in all treatment groups with stressor-specific dynamic profiles. Improved force generation in the EXAC soleus coincided with significant up-regulation in expression levels of genes encoding sarcoplasmic Ca2+-transporting proteins (SERCA2 and inositol triphosphate receptor), glycolysis rate-limiting enzyme (phosphofructokinase), mitochondrial lipid metabolism (CPTII), and stress proteins with antiapoptotic or apoptotic activity. Our data suggest that EXAC-specific gene up-regulation and cross talk between genes assigned to their gene ontology categories (transport, metabolism, and stress) differ in abundance and/or expression level (compared with other treatment groups) and contributed to the physiological advantage demonstrated by the EXAC soleus.

Mice Receiving Infrared Irradiation Have a Higher Survival Rate Under Forced Swimming in Cold

To explore the effect of infrared (IR) irradiation on the survival rates of mice under forced swimming in cold conditions. IR irradiation has been found to be beneficial for wound healing, tumor reduction, pain relief, and even against depression. However, whether the antidepressant effect of IR irradiation came from heat has remained unanswered. The goals of the study were originally aimed at using an animal model for depression to understand the relationship between the antidepressant effect of IR irradiation and hyperthermia as well as seasonality. Forty-four mice were housed in cages in a room subject to the outdoor temperature, and randomly assigned to the IR-treated group (n = 15), the heat-treated group (n = 14), and the control group (n = 15) during winter. The mice of the IR-treated group received whole-body IR irradiation for 60 min daily, while the heat-treated group received heat diffusion to reach the same temperature level. The control group received neither IR nor heat. All groups of mice underwent a forced swimming test weekly. Incidentally, two episodes of cold current occurred during the study period, and some mice died. The survival rates were compared pairwise against the control. The IR-treated group had a significantly reduced relative risk (p = 0.013) when compared with the control group, while the heat-treated group did not show any significant reduction (p = 0.087). There was no significant difference in body temperatures of the three groups before and after the irradiation. IR irradiation resulted in a significantly higher survival rate for mice that were concurrently subjected to cold and a forced swimming test. This result may be beyond the thermal effect.

Geranylgeranylacetone protects rat and striatum neurons against heat injury via induction of Hsp70

GGA (geranylgeranylacetone) may induce Hsp70 synthesis, thus contributing to the protective effects of GGA in several disease states. This study evaluated the protective effects of GGA against heat injury to rat and striatum neurons in terms of mechanisms. Rats were exposed to 41.5 °C for 35 min to induce heatstroke; the protective effects of GGA were then evaluated by change in rectal temperature (Tre) during heat exposure and survival time after heatstroke. Primary cultured striatum neurons were incubated with GGA for 24 h, and then heat-treated at 43 °C for a further 1 h. The viability, membrane surface ultrastructure and Hsp70 expression of striatum neurons were all observed. Furthermore, the effects of quercetin an inhibitor of Hsp70 synthesis were also investigated. Compared to the heatstroke group, GGA delayed Tre in reaching 42.1 °C ( P < 0.05) and prolonged the survival time after heatstroke ( P < 0.01). The LDH releasing percentage decreased in GGA groups ( P < 0.05, P < 0.01) compared to the heat-treatment group and increased in quercetin groups ( P < 0.05) compared to GGA group. Results from AFM showed that GGA protected membrane surface ultrastructure against heat injury. In addition, results from Western blot showed that GGA-induced Hsp70 expression of neurons both in normal and heat-treatment conditions ( P < 0.01, P < 0.05) and quercetin inhibited GGA-induced Hsp70 expression ( P < 0.05). Therefore, GGA had protective effects against heat injury in striatum neurons and rat heatstroke. Quercetin inhibited GGA-induced Hsp70 expression and prevented GGA-protective effects, which indicated that this protection was dependent on the Hsp70 synthesis.

3 SELECTION OF UNFRAGMENTED-DNA SPERMATOZOA FROM HEAT STRESSED MICE BY FEMALE UTERINE TRACT AND ZONA PELUCIDA BINDING

Physiological bases of the sperm selection processes within the female reproductive tract before they meet and fertilize the oocyte are unknown. The aim of this work was to determine if one of the keys of spermatozoa selection could be DNA integrity. It has been reported that sperm DNA damage does not impair in vitro fertilization (IVF). However, it has been suggested that the zona pelucida (ZP) is able to select spermatozoa with unfragmented DNA (Liu and Baker 2007 Hum. Reprod. 22, 1597–1602). In this work, DNA damage of spermatozoa was artificially induced by scrotal heat treatment (HT) (42°C, 30 min). Twenty-one days after the HT, spermatozoa were recovered from the epididymis caudae of CD1 mice and from the uterine horns near the cervix (Uc), from the uterine horns near the oviducts (Uo), and from the oviducts (Ov) of CD1 females 1–2 h after mating with HT and control males. In each region we determined numbers of spermatozoa, individual motility and sperm DNA integrity by COMET assay (% DNA in tail, tail length, and COMET moment was calculated). Also, females naturally mated either with HT or control males were killed at Day 14 of pregnancy, and number of foetuses and resorptions was recorded. Additionally, IVF was performed with epididymal sperm from HT or control males, Two hours after IVF attached and un-attached spermatozoa to the ZP were recovered and samples were evaluated for sperm motility (CASA), sperm zona-binding, and sperm DNA fragmentation (COMET). Also cleavage rate of fertilized oocytes with sperm from HT or control males was analyzed. One-way ANOVA was used to compare the results form each group. Epididymal sperm count (12*106 and 4.4*106 for control and HT respectively), sperm motility (75 and 21% respectively) and testis weight (133.90 and 68.76 mg, respectively) were significantly reduced after heat treatment (P &lt; 0.001). For the heat treatment, COMET values decreased significantly during the transit from Uc to Uo and from Uo to Ov (Tail DNA: 25.7, 23.5, and 14.4% respectively, P &lt; 0.01; Tail length: 38.4, 29.4, and 11.2 pixels, P &lt; 0.001; COMET Moment: 12.5, 8.5, and 2 respectively, P &lt; 0.001). Heat treatment reduced numbers of foetuses (7 ± 0.5 v. 5 ± 0.49, control and HT group, respectively), but number of resorptions was not altered. Spermatozoa bound per ZP in IVF experiments (55 ± 7 and 13 ± 6, control and HT, respectively) and cleavage rate (61 ± 1 v. 15 ± 6, control and HT, respectively) were significantly reduced in the HT group. Two hours after IVF, spermatozoa attached to the ZP in HT group showed a significant decrease in COMET parameters as in tail length (59.46 ± 2.895 v. 34.66 ± 3.531), and in tail moment compared with unattached spermatozoa. Our results indicate that DNA integrity sperm selection mechanisms are present in both the female tract and the ZP. We suggest that genital tract and sperm-ZP binding process plays an important role in selection of sperm with normal chromatin DNA.