• Title/Summary/Keyword: human physiology

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Relationships between Insensible Perspiration and Thermo Physiological Factors during Wearing Seasonal Clothing Ensembles in Comfort (쾌적한 상태에서 계절별 의복을 착용하고 있는 동안 불감증설과 온열 생리 요소들 간의 관련성)

  • Lee, Joo-Young;Choi, Jeong-Wha;Park, Joon-Hee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.31 no.12
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    • pp.1700-1709
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    • 2007
  • The purpose of this study was to examine the relationships between thermo-physiological factors and the insensible loss of body weight(IL) of resting women wearing seasonal comfortable clothing. Air temperature was maintained at a mean of 22.5, 24.7, and 16.8 for spring/fall, summer and winter, respectively. We selected a total of 26 clothing ensembles(8 ensembles for spring/fall, 7 ensembles for summer, and 11 ensembles for winter). The results showed that 1) IL was $19{\pm}5g{\cdot}m^{-2}{\cdot}hr$ for spring/fall environment, $21{\pm}5g{\cdot}m^{-2}{\cdot}hr$ for summer, $18{\pm}6{\cdot}m^{-2}{\cdot}hr$ for winter(p<.001). 2) Insensible water loss through respiratory passage(IWR) showed the reverse tendency to IL. IWR was $6{\pm}1g{\cdot}m^{-2}{\cdot}hr$ for winter and $5{\pm}1g{\cdot}m^{-2}{\cdot}hr$ for summer. This difference was significant(p<.001). 3) The proportion of IWR out of whole insensible water loss(IW), had a mean of the mean 28% for summer and 38% for winter(p<.001). 4) In comfort, the heat loss by IW out of heat production had a mean of 25% for spring/fall, 27% for summer, and 23% for winter. 5) There was a weak negative correlation between It and clothing insulation/body surface area covered by clothing. 6) There were significant correlations between IL and air temperature$(T_a)$, air humidity$(H_a)$, energy metabolism, ventilation, mean skin temperature $\={T}_{sk})$ and clothing microclimate humidity$(H_{clo})$. However, the coefficients were less than 0.5. In conclusion, there were weak relationships between the IL and thermo-physiological factors. However, when subjects rested in thermal comfort, the IL was maintained in a narrow range even though the clothing insulation and air temperature were diverse.

Effect of Genistein on the Onset of Puberty in Female Rats (암컷 흰쥐의 사춘기 개시에 미치는 Genistein의 효과)

  • Lee, Kyeung-Yeup;Lee, Sung-Ho
    • Development and Reproduction
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    • v.10 no.1
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    • pp.55-61
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    • 2006
  • There is growing concern that dietary soy intake is associated with protection of breast cancer. However, questions persist on the potential adverse effects of the main soy constituent genistein(GS) on female reproductive physiology. In this study, we examined whether prepubertal exposure to GS affected on the onset of puberty and the associated reproductive parameters such as hormone receptor expressions in female rats. GS(100mg/kg/day) was administrated daily from postnatal day 25(PND 25) to the day when the first vaginal opening(VO) was observed, and the animals were sacrificed on the day after VO occurred. Gross anatomy and tissue weight were compared to test the GS's effect on the cell proliferation. Furthermore, histological studies were performed to assess the structural alterations in tissues. Specific radioimmunoassay(RIA) were carried out to measure serum LH levels. To determine the transcriptional changes in progesterone receptors(PR), total RNAs were extracted from ovary and uterus and were applied to semi-quantitative reverse transcription polymerase chain reaction(RT-PCR). As a results, advanced VO was shown in the GS group(PND $31.2{\pm}0.6$) compared to the vehicle group (PND $35.3{\pm}0.7$). GS treatment significantly increased wet weight of ovaries and uteri compared to the vehicle group. Increased serum LH levels were also shown in the GS group. Graafian follicles and corpora lutea(CL) were observed only in the ovaries from GS treated animals. Similarly, hypertrophy of luminal and glandular uterine epithelium were found only in the GS group. Collectively, these effects were probably due to the estrogenic effects of GS. In the semi-quantitative RT-PCR studies, the transcriptional activities of PR in both ovary and uterus from GS-treated group were significantly higher than those from the vehicle group. The present studies demonstrated that acute exposure to GS, at levels comparable to the ranges of human exposure, during the critical period of prepubertal stage activates the reproductive system resulting precocious puberty in immature female rats.

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Yield and Fruit Quality of Pepper as Affected by Different Liquid Fertilizer in Organic Farming (고추 유기농 재배 시 액비처리에 따른 수량 및 품질)

  • Nam, Chun-Woo;Cho, Young-Sang;Moon, Hee-Ja;Chae, Soo-Young;Yang, Eun-Young;Cho, Myeong-Cheoul
    • Korean Journal of Organic Agriculture
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    • v.28 no.3
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    • pp.387-403
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    • 2020
  • This experiment was carried out to determine optimal concentration of organic liquids for the improvement of antioxidant in pepper. As human beings enter the age of 100, they are naturally recognized as a standard of high quality agricultural products for safety and improvement of functional materials. Tomatoes are among the most consumed vegetables in the world and there is a growing interest in varieties with high functional content. However, there is a limit to the improvement of functional materials of certain varieties, so it is necessary to study the improvement of materials by cultivation physiology and environmental conditions. The test material was sown on March 15th in Wanju province and on June 15th in rain shelter house using pepper "suppermanidda" varieties. To investigate the optimum concentration of organic liquids for the improvement of antioxidant, 15 kinds of treatments were carried out including control, tomato liquid fertilizer etc. The liquid fertilizer of organic material was treated with 6 times of irrigation, and the analysis of nutrients and antioxidant was done by harvesting pepper on the September 10th. The contents of beta-carotene was increased in the T3, T4, T12 treatments, vitamin C was in the P14 treatments, flavonoid, polyphenol were in the P12 treatment compared to the control. In T12 treatment, flavonoid increased by 115.9%, polyphenol by 121.7%, beta-carotene by 117.2% and vitamin C by 136.1% compared to the control. There was no significant difference in the growth characteristics and characteristics of pepper fruit of pepper according to liquid fertilizer treatment. Therefore, it has been confirmed that the organic antioxidant is affected by the liquid fertilizer treatments of organic materials and it is necessary to study the environmental conditions such as temperature, moisture and photosynthesis.

Protective Effect of Nitroglycerin on the Ischemia-Reperfusion Model of the Isolated Rat Lung (흰쥐의 분리 폐장 관류 모델에서 Nitroglycerin의 폐장 보존 효과)

  • Jheon, Sang-Hoon;Lee, Sub;Lee, Jong-Hoon;Son, Bok-Kyoung;Cho, Gong-Rae;Chung, Jin-Yong;Cho, Soung-Kyung;Kim, Bong-Il;Lee, Young-Man;Choh, Joong-Haeng
    • Journal of Chest Surgery
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    • v.36 no.12
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    • pp.894-903
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    • 2003
  • Protection against ischemia-reperfusion injury is crucial for successful transplantation of the lung. It has been known that nitric oxide has many favorable effects on the donor lungs but at the same time, has some potential side effects of cytotoxicity. In this regards, we investigated whether the administration of nitroglycerin could decrease ischemia-reperfusion injury in isolated rat lung reperfusion model for the confirmation of the effect of nitroglycerin, a donor of nitric oxide, on lung transplantation. Material and Method: 35 Sprague-Dawley species male white rats were used for this experiment. For nitroglycerin group (n=18), nitroglycerin was administered intravenously followed by mixed in flushing solution for preservation. As a control group (n=17), we used the same amount of normal saline. To evaluate the effect of nitroglycerin on the lung, heart-lung block was obtained, weighed and stored in University of Wisconsin Solution at 1$0^{\circ}C$ for 24 hours. In each group of the isolated lungs, reperfusion was carried out with Krebs-Hensleit-diluted human blood for 60 minutes. As parameters of the state of the isolated lung, peak inspiratory and pulmonary arterial pressures were continuously recorded. Oxygen and carbon dioxide tension of reperfusing blood were measured before and after 30, 60 minutes of reperfusion. After sixty minutes of reperfusion, protein content in bronchoalveolar lavage fluid was measured also for the evaluation of the degree of alveolar flooding. Lung myeloperoxidase activity was determined to verify the accumulation of neutrophils. Results: Although statistically significant differences were not noted in peak inspiratory and pulmonary arterial pressure between control and nitroglycerin group, latter group showed lowering tendency of pulmonary arterial pressure during the entire reperfusion period. Oxygen tension was higher (p<0.05) in nitroglycerin group compared with that of the control group, in contrast, there were no differences in carbon dioxide tension, protein content in bronchoalveolar lavage fluid and myeloperoxidase activity between the groups. In the examination of ultrastructural changes, nitroglycerin denoted the protective effect on the pulmonary architecture compared with that of control group. Conclusion: Collectively, on the bases of these experimental results, prior treatment of donor lung with nitroglycerin could result in better preservation of the lung. Consequently, these nitroglycerin preserved lungs are thought to be more suitable for successful transplantation of the lung.

An Experimental Study on the Early Feeding of Infants (신생아의 조기수유에 관한 실험적 연구)

  • 하영수
    • Journal of Korean Academy of Nursing
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    • v.5 no.1
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    • pp.1-16
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    • 1975
  • The newborn human is the only mammalian whose mother does not have a food supply ready for it's offspring at birth. From two to four days usually elapse before the mother's supply If milk appears, and during this period, some kind of artificial feeding should be supplied to the infants. Because of this factor, there has been continued debate fog the past hundreds of years as to when the first feeding should be started Accordingly, many experiments were carried out by scholars and because of these, Pre-lateral feedings were believed to be necessary. Many types of pre-lateral feedings were tried and the conclusion was reached that glucose water was the best food for the first infants'feedings. Traditionally, This has been started 12 hours after birth. The causes for the 12 hours delay were thought to (1) provide rest for the infants: (2) prevent regurgitation ana vomiting which tended to be prevalent during this tine: (3) in cases of low weight infants, prevention of aspiration pneumonia. From recent studies of newborn physiology and as pediatric medicine has been rapidly advancing, many studies hare been carried out concerning the improvement of infant nutrition and the early feeding of infants has been emphasized. This author believes it would be very beneficial to try two different kinds of feedings for the infant. (1) experimental feedings ana (2) comparative feeding, and during this period to investigate and compare the infants blood sugar level, hematocrit, gamma globulin level weight changes and to observe the infant reaction ill order to search for a more desirable feeding program. This study was conducted from January to March 1974 with data related to 40 healthy newborn infants (male 21, female 19: weight, 2.79∼4.20㎏ : gestation, 39∼40 weeks) born at Ewha Womens University Hospital and the results obtained were as follows : 1. At time of birth the blood sugar level from the cord sample averaged 88.99㎎/100㎖, but the blood sugar level rapidly dropped after 2 to 3 hours and reached the lowest point after 10 to 11 hours (54.48㎎/100㎖) and rose again by the 24 hour time period (76.80㎎/100㎖). Changes in the blood sugar level of the experiments: groups and the compare-five group was not significantly different until the 6 to 7 hour period, but by the 10 to 11 hour period the blood sugar levels of the experimental group (49,10㎎/100㎖) and the comparative group (49.70㎎/100㎖) were lower than the remainder of the experimental groups. 9. There ware no significant weight changes between the two groups. Average weight at birth was 3.35㎏, but at the 24 hours period birth weight averaged 3.29㎏. (1.8% reduction of birth weight). It continually lowered until at 48 hours, average weight was 3.26㎏ (2.7% reduction from birth weight.) 3. Hematocrit readings showed no significant difference between the groups. Hematocrit, the average value at birth, was 28.07% and abruptly elevated to average 64.35% at the 2 to 3 hour period, then slowly lowered to an average of 59.67% at the 6 to 7 hour period, 55.10% at the 10 to 11 hour period, ana 53.70% at the 24 hour period. 4. At birth, average gamma globulin value averaged 1,39㎎/100㎖. and at the 24 hour period averaged 1,52㎎/100㎖ revealing no significant difference between the two feeding groups. 5. Such factors as voiding, passing of meconium, regurgitation and vomiting showed no significance between the two feeding groups. However, the number of infants voiding and passing meconium in the experimental groups during the first 12 hours was slightly greater. In general there was an increased tendency for regurgitation and. vomiting among a small group of the infants during the first 24 hours which thereafter decreased. 6. Fluid intake averaged 24.38cc at the first feeding and increased to average 30.48cc at the third feeding and further increased to 73. 00cc at the fifteenth feeding. Finally it was suggested that the most reasonable method of early feeding is to give less than 25cc of 5% glucose water and/or 8% powdered milk at 8 to 9 flours after birth in order to prevent hypoglycemia and dehydration.

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Review of Anti-Leukemia Effects from Medicinal Plants (항 백혈병작용에 관련된 천연물의 자료조사)

  • Pae Hyun Ock;Lim Chang Kyung;Jang Seon Il;Han Dong Min;An Won Gun;Yoon Yoo Sik;Chon Byung Hun;Kim Won Sin;Yun Young Gab
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.17 no.3
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    • pp.605-610
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    • 2003
  • According to the Leukemia and Lymphoma Society, leukemia is a malignant disease (cancer) that originates in a cell in the marrow. It is characterized by the uncontrolled growth of developing marrow cells. There are two major classifications of leukemia: myelogenous or lymphocytic, which can each be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. Thus, four major types of leukemia are: acute or chronic myelogenous leukemia and acute or chronic lymphocytic leukemia. Leukemia, lymphoma and myeloma are considered to be related cancers because they involve the uncontrolled growth of cells with similar functions and origins. The diseases result from an acquired (not inherited) genetic injury to the DNA of a single cell, which becomes abnormal (malignant) and multiplies continuously. In the United States, about 2,000 children and 27,000 adults are diagnosed each year with leukemia. Treatment for cancer may include one or more of the following: chemotherapy, radiation therapy, biological therapy, surgery and bone marrow transplantation. The most effective treatment for leukemia is chemotherapy, which may involve one or a combination of anticancer drugs that destroy cancer cells. Specific types of leukemia are sometimes treated with radiation therapy or biological therapy. Common side effects of most chemotherapy drugs include hair loss, nausea and vomiting, decreased blood counts and infections. Each type of leukemia is sensitive to different combinations of chemotherapy. Medications and length of treatment vary from person to person. Treatment time is usually from one to two years. During this time, your care is managed on an outpatient basis at M. D. Anderson Cancer Center or through your local doctor. Once your protocol is determined, you will receive more specific information about the drug(s) that Will be used to treat your leukemia. There are many factors that will determine the course of treatment, including age, general health, the specific type of leukemia, and also whether there has been previous treatment. there is considerable interest among basic and clinical researchers in novel drugs with activity against leukemia. the vast history of experience of traditional oriental medicine with medicinal plants may facilitate the identification of novel anti leukemic compounds. In the present investigation, we studied 31 kinds of anti leukemic medicinal plants, which its pharmacological action was already reported through many experimental articles and oriental medical book: 『pharmacological action and application of anticancer traditional chinese medicine』 In summary: Used leukemia cellline are HL60, HL-60, Jurkat, Molt-4 of human, and P388, L-1210, L615, L-210, EL-4 of mouse. 31 kinds of anti leukemic medicinal plants are Panax ginseng C.A Mey; Polygonum cuspidatum Sieb. et Zucc; Daphne genkwa Sieb. et Zucc; Aloe ferox Mill; Phorboc diester; Tripterygium wilfordii Hook .f.; Lycoris radiata (L Her)Herb; Atractylodes macrocephala Koidz; Lilium brownii F.E. Brown Var; Paeonia suffruticosa Andr.; Angelica sinensis (Oliv.) Diels; Asparagus cochinensis (Lour. )Merr; Isatis tinctoria L.; Leonurus heterophyllus Sweet; Phytolacca acinosa Roxb.; Trichosanthes kirilowii Maxim; Dioscorea opposita Thumb; Schisandra chinensis (Rurcz. )Baill.; Auium Sativum L; Isatis tinctoria, L; Ligustisum Chvanxiong Hort; Glycyrrhiza uralensis Fisch; Euphorbia Kansui Liou; Polygala tenuifolia Willd; Evodia rutaecarpa (Juss.) Benth; Chelidonium majus L; Rumax madaeo Mak; Sophora Subprostmousea Chunet T.ehen; Strychnos mux-vomical; Acanthopanax senticosus (Rupr.et Maxim.)Harms; Rubia cordifolia L. Anti leukemic compounds, which were isolated from medicinal plants are ginsenoside Ro, ginsenoside Rh2, Emodin, Yuanhuacine, Aleemodin, phorbocdiester, Triptolide, Homolycorine, Atractylol, Colchicnamile, Paeonol, Aspargus polysaccharide A.B.C.D, Indirubin, Leonunrine, Acinosohic acid, Trichosanthin, Ge 132, Schizandrin, allicin, Indirubin, cmdiumlactone chuanxiongol, 18A glycyrrhetic acid, Kansuiphorin A 13 oxyingenol Kansuiphorin B. These investigation suggest that it may be very useful for developing more effective anti leukemic new dregs from medicinal plants.

Effect of Asarum sieboldii Extracts on the Growth, Acid Production, Adhesion, and Insoluble Glucan Synthesis of Streptococcus mutans (세신 추출물의 Streptococcus mutans에 대한 성장, 산생성, 부착 및 비수용성 글루칸 합성억제에 미치는 영향)

  • Yu Hyeon Hee;Seo Se Jeong;Kim Yeon Hwa;Lee Heung Soo;Kim Kang Ju;Jeon Byung Hun;You Yong Ouk
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.17 no.3
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    • pp.666-671
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    • 2003
  • Dental caries are the most commonly occurring chronic diseases in the dental field. Because of increasing sugar consumption and extension of average human life, these diseases are widely found all over the world as the most typical cause for a person to lose a tooth. Therefore, the development of more effective, substantial and safe preventive agents against dental caries is strongly required. Streptococcus mutans is known as the causative bacterial playing the most important role informing plaque and it is being noticed as major causative bacteria of dental caries. The present study was designed to investigate the effect of Asarum sieboldii Miquel(Aristolochiaceae) extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of Streptococcus mutans(S. mutans). Both methanol and aqueous extracts showed concentration dependent inhibitory activity against the growth and acid production of S. mutans, and produced significant inhibition at the concentration of 100, 1,000 and 2,000 μg/ml compared to the control group(p<0.05 - p<0.01). The extracts markedly inhibited S. mutans adherence to HA treated with saliva, and cell adherence was repressed by more than 50% at the concentration of 10 μg/ml and complete inhibition was observed at the concentration of 2,000 μg/ml. On the activity of glucosyltransferase which synthesizes water insoluble glucan from sucrose, methanol and aqueous extracts showed more than 70% inhibition over the concentration of 1,000 μg/ml. Hence, we conclude that Asarum sieboldii might be a candidate of anticaries agent.

Antioxidant Effect of Hederagenin 3-O-b-D-Glucopyranosyl(1→3)-a-L-Rhamnopyranosyl(1→2)-a-L-Arabinopyranoside (HDL) Isolated from Root Bark of Ulmus davidiana (유근피로부터 분리한 hederagenin 3-O-b-D-glucopyranosyl(1→3)-a-L-rhamnopyranosyl(1→2)-a-L-arabinopyranoside (HDL)의 항산화 효과)

  • Bong, Jin-Gu;Park, Yoon-Yub
    • Journal of Life Science
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    • v.20 no.2
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    • pp.281-291
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    • 2010
  • We investigated the antioxidant effects of hederagenin 3-O-b-D-glucopyranosyl($1{\rightarrow}3$)-a-L-rhamnopyranosyl($1{\rightarrow}2$)-a-L-arabinopyranoside (HDL) isolated from root bark of Ulmus davidiana on the activity of enzymes related to reactive oxygen species (ROS) in human osteosarcoma U2OS cells. Cobalt chloride ($CoCl_2$), a transition metal, was used as an inducer of oxidative stress, generating hydrogen peroxide ($H_2O_2$) via increasing xanthine oxidase (XO) activity. The increased levels of $H_2O_2$, XO, ferritin, and ferritin iron by $CoCl_2$ were diminished effectively by co-treatment with HDL in U2OS cells. Furthermore, decreased levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) by $CoCl_2$ were highly increased by co-treatment with HDL in U2OS cells; however, the levels of glutathione peroxidase (GPx) did not change. The increased contents of TBARS related to lipid peroxidation were significantly reduced by HDL in U2OS cells. The concentration of GSH changed in a pattern that went against regulated TBARS by $CoCl_2$ and HDL. We examined the expression of p53, $p21^{CIP1/WAF1}$, and $p27^{KIP1}$ proteins related to oxidative stress and cell cycle regulation. As a result, the expression of $p27^{KIP1}$ modulated by $CoCl_2$ was not changed by HDL. However, the expression of p53 and $p21^{CIP1/WAF}$ increased by $CoCl_2$ was reduced by HDL in U2OS cells. Together with alteration of p53 and $p21^{CIP1/WAF1}$ proteins, the accumulated cells at G1 phase by $CoCl_2$ was decreased by HDL in U2OS cells. Our data suggests that HDL inhibits $CoCl_2$-generated ROS in U2OS cells, providing potentially new antioxidant compounds that are isolated from natural products.

EFFECTS OF MOISTENING OF ETCHED DENTIN AND ENAMEL SURFACES ON BOND STRENGTH (산 표면처리후 상아질과 법랑질 표면의 습윤이 결합강도에 미치는 영향)

  • Lee, Kwang-Won;Park, Soo-Joung;Son, Ho-Hyun
    • Restorative Dentistry and Endodontics
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    • v.20 no.1
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    • pp.328-341
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    • 1995
  • I. Shear Bond Strength to Air-dried and Remoistened Dentin.. The effect of air-drying and remoistening of acid-conditioned dentin before priming with the primer of All-Bond 2(BISCO. INC., U. S. A.) on shear bond strength(SBS) was investigated. Ninty freshly extracted sound human molars were divided at random into 9 groups of 10 teeth each. SBSs were meaured for acid-conditioned and non-conditioned dentin to which the primer and bonding agent of All-Bond 2 and composite resin(Z-100, 3M Dental Products, U. S. A.) were applied. The following values(Mean${\pm}$ SD, MPa) were obtained for the groups conditioned with 10% phosphoric acid for 15 seconds: Group l(blot dried) $6.7{\pm}4.1$ ; Group 2(10 seconds dried) $16.1{\pm}5.3$ ; Group 3(20 seconds dried) $15.4{\pm}4.8$ ; Group 4(30 seconds dried) $15.2{\pm}6.3$ ; Group 5(10 seconds dried/remoistened) $26.4{\pm}2.6$ ; Group 6(20 seconds dired/remositened) $22.2{\pm}2.7$ ; Group 7(30 seconds dried/remoistened) $21.5{\pm}4.1$. For the non-conditioned groups the values were: Group 8 (blot dried) $13.3{\pm}2.6$ ; Group 9(10 seconds dried) $12.9{\pm}3.5$. The data were analyzed using ANOVA. In the acid-conditioned groups, mean values of SBS for the air-dried specimens(Grps. 2, 3 and 4) and the 20 and 30 seconds dried/remoistened specimens (Grps. 6 and 7) were significantly lower than that of blot dried specimens.(p<0.05) The value for 10 seconds dried/remoistened specimens (Grp. 5), however, was not statistically different compared to that of blot dried specimens.(p>0.05) In the non-conditined groups, there was no statistical difference between blot dried and 10 seconds dried specimens.(p>0.05) The results suggest that the acid-conditioned dentin surface is more vulnerable to dentin bonding when it is air-dried or even remoistened after long period of drying. II. Shear bond stengh to the moistened and primed enamel. The effect of moistening and priming of enamel compared to the air-drying of enamel on the shear bond strength of enamel bonding agent was investigated. The experiment was divided into 4 groups each containing 10 caries-free maxillary incisor teeth. Shear bond strength values were measured for the primed and non-primed enamel to which All-Bond 2 and Z-100 were applied. The following values(MPa) were obtained for the primed groups pretreated with 32 % phosphoric acid for 15 seconds. : Group 1 (10 seconds dried) $29.8{\pm}2.2$ ; Group 2(moistened) $26.8{\pm}5.4$. For the non-primed groups the values were: Group 3(10 seconds dried/primed) $27.6{\pm}5.0$ ; Group 4(mostened/primed) $28.2{\pm}3.5$. The data were subjected to statistical analysis using ANOVA. The results showed that mean shear bond strengths among the experimental groups were not statistically different. (p>0.05) Conclusively, It is suggested that the bonding ability to enamel is not decreased by the moistening and priming of the enamel.

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Role of Ghrelin in the Control of Reproductive Endocrine Function (포유류 생식 내분비 기능 조절에서 Ghrelin의 역할)

  • Lee, Sung-Ho
    • Development and Reproduction
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    • v.13 no.4
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    • pp.207-215
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    • 2009
  • Numerous factors can affect the activities of hypothalamus-pituitary-gonad (HPG) hormonal axis, resulting in alteration of reproductive capacity or status such as onset of puberty and menopause. Soon after the finding of leptin, a multifunctional hormone secreted from adipocytes, a close relationship between reproduction and body energy balance have been manifested. Ghrelin, another multifunctional hormone from gastrointestinal tract, is an endogenous ligand of growth hormone secretagogue receptor (GHSR), and is thought to be a counterpart of leptin in the regulation of energy homeostasis. As expected, ghrelin can also modulate the reproductive capacity through the modulation of activities of HPG axis. This paper summarizes the current knowledge on the discovery, gene structures, tissue distribution and roles of ghrelin and GHSRs in mammalian reproduction in particular modulation of reproductive hormone secretion in HPG axis. Like POMC gene expression in pituitary gland, preproghrelin gene can generate a complex repertoire of transcripts which further undergo alternative splicing and posttranslational modifications. Concerning the roles of preproghrelin gene products in the control of body physiology except energy homeostasis, limited knowledge is available so far. Several lines of evidence, however, show the interplay of ghrelin between metabolism and reproduction. In rat and human, the distribution of ghrelin receptor GHSRs (GHSR1a and GHSR1b) has been confirmed not only in the hypothalamus and pituitary which were originally postulated as target of ghrelin but also in the testis and ovary. Expression of the preproghrelin gene in the brain and gonads was also verified, suggesting the local role (s) of ghrelin in HPG axis. Ghrelin might play a negative modulator in the secretions of hypothalamic GnRH, pituitary gonadotropins and gonadal steroids though the action on pituitary is still questionable. Recent studies suggest the involvement of ghrelin in regulation of puberty onset and possibly of menopause entry. It is now evident that ghrelin is a crucial hormomal component in 'brain-gut' axis, and is a strong candidate links between metabolism and reproduction. Opposite to that for leptin, ghrelin signaling is likely representing the 'hunger' state of body energy balance and is necessary to avoid the energy investment into reproduction which has not a top priority in maintaining homeostasis. Further researches are needed to gain a deep insight into the more precise action mechanism and role of ghrelin in reproduction, and to guarantee the successful biomedical applications.

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