• Journal of Dairy Science and Biotechnology
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• v.34 no.1
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• pp.37-41
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• 2016

Melatonin is a hormone produced by the pineal gland in dark conditions. It plays a major role in the regulation of the sleep-wake cycle. Melatonin synthesis is known to be suppressed by environmental light. Cortisol is a steroid hormone that is a major indicator of physiological alterations due to stressful stimuli. It also displays a circadian rhythm, like melatonin. The highest levels are encountered during early morning and the lowest levels are observed at around midnight. In the present study, the effects of milking time on the melatonin and cortisol concentrations of raw milk and milk powder at the summer and winter solstices were examined. The melatonin concentration in milk increased significantly if cows were milked in the dark at night (p<0.05). The melatonin concentration in milk powder showed the same pattern with respect to the milking time (p<0.05). However, no significant difference in the cortisol concentration was observed between day- and night-time milk. Although the time of day did not affect the level of milk cortisol, seasonal factors affected the release of cortisol in milk (p<0.05). In conclusion, night-time milk is rich in endogenous melatonin. In this respect, it has potential applications for the development of melatonin rich-dairy products, which serve as natural sources of melatonin.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.3
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• pp.155-168
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• 2004

Objective: Melatonin, which is secreted by pineal gland play an important role in the regulation of ovarian function via seasonal rhythm and sleep in most mammals. It also has a role in the protection of cells by removing toxic oxygen free radicals brought about by metabolism. In the present study, effects of melatonin on the mouse oocyte maturation were examined using two different culture conditions provided with 5% or 21% oxygen concentration. Material and Method: Immature mouse oocytes were obtained from the ovarian follicles of $3{\sim}4$ weeks old ICR strain mice intraperitoneally injected with 5 I.U. PMSG 44 hour before. Under stereomicroscope, morphologically healthy oocytes with distinct germinal vesicle (GV) were liberated from the graafian follicles and collected using mouth-controlled micropipette. They were then cultured for 17 hour at $37^{circ}C$, 5% $CO_2$ and 21% $O_2$ (95% air) or 5% $CO_2$, 5% $O_2$ and 90% $N_2$. New modified Hank's balanced salt solution (New MHBS) was used as a culture medium throughout the experiments. Effects of melatonin were examined at a concentration of $0.0001{\mu}M$, $0.01{\mu}M$ or $1.0{\mu}M$. For the prevention of spontaneous maturation of immature oocytes during culture, dibutyryl cyclic AMP (dbcAMP) and/or hypoxanthine were included in the medium. Results: Under 21% oxygen condition, oocytes cultured in the presence of $0.01{\mu}M$ melatonin showed a significantly higher maturation rates, in terms of germinal vesicle breakdown (95.0% vs 89.0%) and polar body formation (88.1% vs 75.4%), compared to those cultured with $0.0001{\mu}M$ or $1.0{\mu}M$ melatonin. However, no difference was observed in oocytes cultured under 5% oxygen whether they were treated with melatonin or not. In the presence of $0.01{\mu}M$ melatonin, oocytes either cultured under 21% or 5% oxygen exhibited no difference in the polar body formation (85.6% vs 86.7%). However, in the absence of melatonin, oocytes cultured under 21% oxygen exhibited lower polar body formation (74.7%). When oocytes were cultured in the presence of dbcAMP alone or with varying concentrations of melatonin, those treated with both compounds always showed better maturation, i.e., germinal vesicle breakdown and polar body formation, compared to those cultured with dbcAMP alone. At the same concentration of melatonin, however, oocytes exposed to 21% oxygen showed poor maturation than those to 5% oxygen. Similar results were obtained from the experiments using hypoxanthine instead of dbcAMP. Conclusion: Based upon these results, it is suggested that melatonin could enhance the meiotic maturation of mouse oocytes under 21% oxygen concentration, and release oocytes from the meiotic arrest by dbcAMP or hypoxanthine regardless of the concentration of oxygen, probably via the removal of oxygen free radicals.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.3
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• pp.223-230
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• 2001

Melatonin, a pineal gland hormone, is believed to act as an antioxidant via the stimulation of radical detoxifying enzymes and scavenging of free radicals. In this study, effects of in vitro and in vivo treatments of melatonin on the cisplatin-induced lipid peroxidation, LDH release and plasma creatinine were determined in rabbit renal cortical cells. The level of malondialdehyde (MDA) was assayed as an index of lipid peroxidation and the level of LDH release as an indicator of cellular damage. In in vitro studies, cisplatin increased the levels of MDA and LDH release in a concentration-and time-dependent manner. Melatonin inhibited the cisplatin-induced lipid peroxidation and LDH release in a concentration-dependent manner. The minimal effective concentration of melatonin that significantly reduced the $300\;{\mu}M$ cisplatin-induced lipid peroxidation and LDH release was 1 mM. In in vivo studies, the levels of lipid peroxidation and LDH release in renal cortical cells increased significantly 24 or 48 hours after a single injection of cisplatin (6 mg/kg). When the cisplatin-injected rabbits were pretreated with 10 mg/kg of melatonin, a significant reduction in both lipid peroxidation and LDH release was observed. The plasma creatinine level increased from $0.87{\pm}0.07$ mg/dl in control to $6.33{\pm}0.54$ mg/dl in cisplatin-injected rabbits (P＜0.05). Melatonin partially prevented the increase in serum creatinine level $(1.98{\pm}0.11\;mg/dl)$ by cisplatin (P＜0.05). In the proximal tubules from cisplatin-treated group, tubular cells had microvilli of variable heights. Necrotic debris was seen in tubular lumens. In most of cells, the mitochondria and lysosomes were increased in frequency. The endocytic vacuoles were not prominent and distribution of the brush border was irregular and shortened. These cisplatin-induced morphological changes were moderate in the melatonin-pretreated group. These results suggest that the toxicity of cisplatin is associated with the generation of reactive oxygen free radicals and that melatonin is a powerful antioxidant, which prevents some of the adverse effects of cisplatin.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.13.1-13.15
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• 2018

Wound healing is delayed in diabetic patients. Increased apoptosis and endothelial progenitor cell (EPC) dysfunction are implicated in delayed diabetic wound healing. Melatonin, a major secretory product of the pineal gland, promotes diabetic wound healing; however, its mechanism of action remains unclear. Here, EPCs were isolated from the bone marrow of mice. Treatment of EPCs with melatonin alleviated advanced glycation end product (AGE)-induced apoptosis and cellular dysfunction. We further examined autophagy flux after melatonin treatment and found increased light chain 3 (LC3) and p62 protein levels in AGE-treated EPCs. However, lysosome-associated membrane protein 2 expression was decreased, indicating that autophagy flux was impaired in EPCs treated with AGEs. We then evaluated autophagy flux after melatonin treatment and found that melatonin increased the LC3 levels, but attenuated the accumulation of p62, suggesting a stimulatory effect of melatonin on autophagy flux. Blockage of autophagy flux by chloroquine partially abolished the protective effects of melatonin, indicating that autophagy flux is involved in the protective effects of melatonin. Furthermore, we found that the AMPK/mTOR signaling pathway is involved in autophagy flux stimulation by melatonin. An in vivo study also illustrated that melatonin treatment ameliorated impaired wound healing in a streptozotocin-induced diabetic wound healing model. Thus, our study shows that melatonin protects EPCs against apoptosis and dysfunction via autophagy flux stimulation and ameliorates impaired wound healing in vivo, providing insight into its mechanism of action in diabetic wound healing.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.184-191
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• 2023

Nuts are essential components of a healthy diet as they provide nutritional value and bioactive components. Melatonin, is a hormone secreted from the pineal gland of the brain that prevents oxidative damage in various tissues, and also found in plants. This study presents a validation method for extracting and quantitatively analyzing melatonin in nuts, seeds, and beans in Gyeonggi-do; the method utilized chromatographic techniques and optimized extraction procedures, considering the high oil content of nuts. The average content of melatonin in nuts, seeds, and beans was 1200.83 (409.76-2223.56), 934.83 (454.10-1736.60), and 616.46 (494.70-825.12) pg/g, respectively. Melatonin content was higher in the kernel with pellicle than that in the kernel alone in walnuts and chestnuts. Furthermore, the presence of melatonin was lower in newly harvested walnuts, chestnuts, and peanuts than in those stored after being harvested the previous year.

• Clinical and Experimental Pediatrics
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• v.49 no.1
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• pp.76-81
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• 2006

Purpose : This study evaluated the clinical characteristics of brain tumors in children according to their location, the parental delay and the doctor's delay between the onset of symptoms and the diagnosis of a pediatric brain tumor. In addition, this study compared the relationship between the pre-diagnostic symptomatic interval and the tumor location. Methods : A retrospective study was undertaken of 45 children with primary brain tumors admitted to Inha Hospital from July, 1986 to June, 2004. A diagnosis of the tumor location was made using brain MRI. Results : The male to female ratio was 1 : 0.67. The median age at diagnosis was 6.0 years in supratentorial tumors, 7.0 years in infratentorial tumors. Twenty four cases(53.3 percent) were located in the supratentorial area, 21 cases(46.6 percent) were located in the infratentorial area. The distribution of supratentorial tumors were 14(58.3 percent) in the cerebral hemisphere and temporal lobe, seven (29.1 percent) in the suprasellar area, and three(12.5 percent) in the pineal gland and posterial lateral ventricle. The distributions of the infratentorial tumors were 12(57.1 percent) in the cerebellar vermis and fourth ventricle, four(19.1 percent) in the brain stem, and five(23.8 percent) in the cerebellar hemisphere. The most common initial symptom was seizure(37.5 percent) in the supratentorial tumor and headache(38.0 percent) in infratentorial tumors. The median pre-diagnostic symptomatic interval (PSI) was 21 days(range 0-240 days). The median PSI with a parental delay in supratentorial tumor was six days(range 1-240 days), and 30 days(range 1-40 days) in the infratentorial tumor. We immediately diagnosed most cases after visiting the hospital. There was no significant relationship between the tumor location and the pre-diagnostic symptomatic interval. Conclusion : The most common symptom of supratentorial tumors and infratentorial tumors was seizure and headache, respectively. Although, the median pre-diagnostic symptomatic interval was shorter than in previous studies, a detailed medical history and a correctly interpreted neurological examination should lead to an earlier diagnosis of pediatric brain tumors.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.93-99
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• 2002

Purpose : We intended to decrease late CNS reaction after radical radiotherapy for an intracranial germinoma by using combined neoadjuvant chemotherapy and involved-field radiotherapy. The efficacy in terms of its acute toxicity and short-term relapse patterns was analyzed. Materials and Methods : Eighteen patients were treated with combined neoadjuvant chemotherapy and radiotherapy between 1995 and 2001. The chemotherapy regimen used was the Children's Cancer Group (CCG) 9921A (cisplatin, cyclophosphamide, VP-16, vincristine) for 5 patients younger than 16 years, BEP (bleomycin, VP-16, cisplatin) for 12 patients, and EP (VP-16, cisplatin) for 1 patient. The radiotherapy covered the whole craniospinal axis for 5 patients, the whole brain for 1, and the partial brain (involved field) for 12. the primary lesion received tumour doses between 3,960 and 5,400 cGy. Results : The male to female ratio was 16:2 and the median age was 16 years old. The tumors were located in the pineal gland in 12 patients, in the suprasellar region in 1, in the basal ganglia In 1, in the thalamus in 1. Three patients had multiple lesions and ventricular seedings were shown at MRI. In 3 patients, tumor cells were detected in the cerebrospinal fluid and MRI detected a spinal seeding in 2 patients. The response to neoadjuvant chemotherapy was complete remission in 5 patients, partial remission in 12, and no response in 1. However, after radiotherapy, all except 1 patient experienced complete remission. The toxicity during or after chemotherapy greater than or equal to grade III was remarkable; hematologic toxicity was observed in 11 patients, liver toxicity in none, kidney toxicity in none, and gastrointestinal toxicity in one. One patient suffered from bleomycin-induced pneumonitis. Radiotherapy was therefore stopped and the patient eventually died of respiratory failure. The other 17 are alive without any evidence of disease or relapse during an average of 20 months follow-up. Conclusion : A high response rate and disease control was experienced, which was the same as observed other studies and the morbidity from chemotherapy-induced toxicity was similar. With these results, the results from adjuvant chemotherapy and involved-field radiotherapy cannot be concluded to be equal to those from extended-field radiotherapy. The long term follow-up study on later complications are required in order to draw definite conclusions on the optimal management with minimum side effects.