Protective Effects of Sunscreens on Sunburn and Suntan Reactions in Cross-bred Mexican Hairless Dogs

Résumé— Les réponses cutanées à l'exposition solaire (radiations UV: 290–400 nm) et l'effet protecteur de deux sortes d'écrans solaires vis-à-vis des coups de soleil et du bronzage ont étéétudié chez des chiens nus descendants de chiens nus Méxicains par trois méthodes (colorimétrie, comptage des mélanocytes DOPA positifs et histologie cutanée). Après la premiére exposition aux UV, alors qu'aucune modification de couleur de la peau (érythème) n'était constatée, les modifications histologiques étaient patentes. Ensuite, après une exposition prolongée, les modifications de couleur étaient nettes (bronzage) et corrélées avec le nombre de mélanocytes DOPA-positifs. Après le troisième jour d'exposition, les mélanocytes étaient retrouvés dans tout l'épiderme des sites non protégés par les écrans solaires et aucune modification de la couleur ni des nombres de mélanocytes n'a été observé dans les zones protégées par les écrans solaires. Histologiquement, seules des modifications mineures ont été notées après 3 à 6 jours d'irradiation UV et il existait des diférences significatives selon la valeur de protection des différents écrans solaires. Par conséquent les écrans solaires protègent efficacement la peau de chiens nus des coups de soleil et du bronzage induits par les expositions solaires. [Kimura, T., Doi, K. Protective effects of sunscreens on sunburn and suntan reactions in cross-bred Mexican hairless dogs (Effet protectuer des écrans solaires vis-à-vis du bronzage et des coups de soleil chez les chiens nus méxicains et croisés). Resumen— Se estudiaron las respuestas cutáneas a la exposición solar (radiación UV 290–400 nm) y los efectos protectores de dos tipos de pantallas solares sobre las quemaduras y bronceados solares en descendientes pelones de perros Pelones Mejicanos utilizando tres métodos distintos [colorimetría, histología y contaje de melanocitos positivos a la dihidroxifenilalanina (DOPA)]. Después de la primera exposición a la radiación UV no se detectó cambio en la coloración de la piel (eritema) aunque si se observaron alteraciones histológicas. Posteriormente, tras sucesivas exposiciones, los cambios de coloración se hicieron visibles (bronceado) y se halló correlación con el número de melanocitos DOPA-positivos. En el tercer dia de exposición, se detectaban melanocitos en toda la epidermis de las zonas desprotejidas pero no se observó ningún cambio de coloración ni aumento de melanocitos en las zonas protejidas por pantallas solares. Histológicamente sólo se detectaron ligeros cambios en la piel protejida al cabo de 3 y 6 dias de radiación UV y existian diferencias entre zonas protejidas con pantallas de diferentes valores SPF. Concluimos que las pantallas solares protegieron la piel de los perros pelones de las quemaduras y bronceado solares. [Kimura, T., Doi, K. Protective effects of sunscreens on sunburn and suntan reactions in cross-bred Mexican hairless dogs (Effectos protectores de las pantallas solares sobre las quemaduras y bronceados solares en perros Pelones Mejicanos cruzados). Zusammenfassung— Es wurden die Hautreaktionen auf Sonnenbestrahlung (UV-Strahlen von 290–400 nm) und die Schutzwirkung von 2 Arten von Sonnenschutzmitteln auf Sonnenbrand und Verfärhungsreaktionen bei haarlosen Abkümmlingen von Mexikanischen Nackthunden mittels dreier Methoden untersucht (Colorimeter, Dihydroxyphenylalanin (DOPA)-positiver Melanozytenzählung und Hauthistologie). Nach der ersten Exposition gegenüber UV-Strahlung konnten histologiesche Veränderungen festgestellt werden, obwohl keine Veränderung der Hautfarbe (Erythem) sichtbar war. Bei der darauffolgenden Exposition traten Farbveränderungen auf (Verfärbungen) und korrelierten mit den Veränderungen der Zahl der festgestellten DOPA-positiven Melanozyten. Am dritten Tag der Exposition konnten Melanozyten in der Epidermis an nicht durch Sonnenschutz bedeckten Stellen festgestellt werden, während an den son-nengeschützten Stellen weder Farbveränderungen noch Melanozytenvermehrung stattfanden. Histologisch konnten auch nach 0 bis 6 Tagen Bestrahlung nur geringgradige Veränderungen in der behandelten Haut ermittell werdem. Es bestanden Unterschiede zwischen Stellen mit Sonneschutzmitteln verschiedener Lichtschutzfaktoren. Sonnenschutzmittel schützen also die Haut von haarlosen. Hurden gegen Sonnenbrand und Verfärbungereaktionen, die durch Sonnenbestrahlung ausgelöst wird. [Protective effects of sunscreens on sunburn and suntan reactions in cross-bred Mexican hairless dogs (Auswirkung von Sonnenschutzmitteln auf Sonnenbrand und Ver färbungsreaktionen bei Mischlingen von Mexikanischen Nackthunden). Abstract— Skin responses to solar exposure (UV radiation: 290–400 nm) and protective effects of two kinds of sunscreens on sunburn and suntan reactions were examined in hairless descendants of Mexican hairless dogs using three methods [colorimeter, dihydroxyphenylalanin (DOPA)-positive melanocyte count and skin histology]. After the first exposure to UV irradiation, while skin color change (erythema) was not detected, histologic changes were apparent. Thereafter, with subsequent exposure, color changes were apparent (tanning) and correlated with changes in numbers of DOPA-positive melanocytes detected. By the third day of exposure, melanocytes were detected throughout the epidermis in sites unprotected by sunscreens but no color change nor increase in melanocytes was noted in sunscreen-protected sites. Histologically, only minor changes were noted in treated skin after 3 and 6 days of UV irradiation, and there were differences between sites treated with sunscreens of different SPF values. Thus, sunscreens effectively protected the skin of hairless dogs from sunburn and suntan reactions induced by solar exposure.     

胡颓子科2种旱生植物次生木质部的生态解剖学特性

从生态学角度对沙棘和沙枣的木材结构进行对比研究.两树种具有的共同特点为 :生长轮明显,半环孔材,具单穿孔,导管间纹孔交互排列,无分隔木纤维,导管较窄, 环管管胞和纤维状管胞具螺纹加厚,轴向薄壁组织缺失或很少.所选树种明显区别是射线类型、宽度和叠生排列方式:沙棘射线,轴向薄壁组织细胞和导管分子具有明显的叠生排列方式,但沙枣的叠生排列不规则;沙棘射线为异型,1～2列,沙枣射线为同型,2～5列;并且二者之间数量化指标有差异,沙棘导管频率较大,导管分子较短及导管管孔较小,因此V和M值也较小,更能适应干旱环境.两树种导管分子长和纤维长的水平变动不规律,并且树种间和同一树种个体间差异显著.本文最后对该树种的解剖学特征和沙漠环境的适应性进行了讨论 .     

3种针叶材年轮宽度和管胞长度变异特性研究

对辽宁省章古台固沙造林研究所的油松、樟子松、赤松人工林木材年轮宽度与管胞长度的测定表明,油松和赤松直径生长旺盛期约为17a,樟子松直径生长旺盛期短于油松和赤松,但樟子松17a后的直径生长高于油松和赤松;3树种的未成熟材范围均大于20a,油松和赤松未成熟材范围基本相等,油松略大于樟子松;三者管胞长度在距离髓心第1～8年轮间基本相等,从距离髓心的第9年轮起,樟子松管胞长度小于油松和赤松;3树种管胞长度在距离地面0．2m高度处出现最小值,油松管胞长度在树干轴向呈“短-长-短”的变化模式,在距地面6m处管胞长度再度出现变短趋势。     

Productivity and energy partition of late lactation dairy cows during heat exposure

Three late-lactation Holstein cows were used to determine the effects of environmental temperature on performance and energy partitioning. Each cow was housed in a respiratory chamber for 30 consecutive days and exposed to three different conditions of environmental temperature: (i) 20°C and 20°C (20°C), (ii) 25°C and 20°C (25°C), (iii) 30°C and 25°C (30°C) during the day and night, respectively. The temperature was switched in an interval of 10 days. Humidity in the chamber was maintained at 55–65% through the entire experimental period. The daily mean as well as morning and evening rectal temperatures of Holstein cows increased linearly ( P  < 0.05) as chamber temperature increased. There was a significant linear reduction in dry matter (DM) intake ( P  < 0.05) and an increase in DM digestibility ( P  < 0.05). The response in milk yield, however, was not affected by heat stress. There were no significant differences among treatments for intake energy, heat production, net energy for lactation and net energy for gain. This results of this study disagreed with the assumption that late lactation cows gave priority to increasing body tissue at the expense of milk production under thermal stress.     

Spectrophotometric assay of a wood preservative, didecyldimethylammonium chloride (DDAC), in aqueous solution

A spectrophotometric assay based on the color reaction between didecyldimethylammonium chloride (DDAC) and 4-[4-(dipropylamino)phenylazo]-benzenesulfonic acid (propyl orange) was used for the determination of DDAC as a wood preservative. The assay was carried out using a propyl orange solution at pH 2.9. The visible absorbance spectrum of propyl orange showed an absorbance maximum at 510 nm, which decreased continuously with increasing DDAC concentration from 0 to 20 ppm. A linear correlation was observed at a DDAC concentration lower than 8 ppm. To apply this assay method to determine DDAC retention in treated wood, the influence of wood extractives on the assay was investigated. Wood extractives from sapwood and heartwood of Japanese cedar, Hinoki cypress, Japanese larch, and Western hemlock showed no influence on DDAC determination except in the case of heartwood from Japanese cedar and Hinoki cypress, which gave apparent DDAC concentrations higher than the actual values. However, it was also found that absorbance measurement at 477 nm solved this overestimation and gave precise values. It was concluded that this assay is a viable alternative to the current methods for DDAC determination.     

Haplotype diversity and molecular evolution of the rice <Emphasis Type="Italic">Pikm</Emphasis> locus for blast resistance

Pikm-specific rice blast resistance is conferred by a combination of two genes that have a nucleotide-binding site and a leucine-rich repeat (LRR), Pikm1-TS and Pikm2-TS. To study the evolution of these genes, we investigated the allele diversity of their LRR regions in 16 elite rice cultivars and 35 landraces. Both phylogenetic trees were characterized by a deep bifurcation that separated two major clades of alleles. A high level of polymorphism was detected exclusively between these clades and not within each clade. This two-clade structure commonly observed for the two genes suggests that these genes have evolved together through bidirectional differentiation.     

Epidemiological study of equine piroplasmosis in Mongolia

The purpose of this study was to demonstrate the occurrence of equine piroplasmosis in Mongolia, a country in which the disease occurs epidemically in different climatic conditions. Antibodies to Babesia equi and B. caballi were determined in serum samples of 254 pastured horses in different locations of Mongolia using an enzyme-linked immunosorbent assay with recombinant antigens. One hundred and eighty-five (72.8%) and 102 (40.1%) of all serum samples were positive for B. equi and B. caballi infections, respectively. In addition, 78 (30.7%) samples were positive for both B. equi and B. caballi infections. These results indicate that equine piroplasmosis is widespread in Mongolia. To our knowledge, this is the first report describing an epidemiological study on equine piroplasmosis in different geographic regions in Mongolia.     

Inactivation of SARS coronavirus by means of povidone-iodine, physical conditions, and chemical reagents

The efficacy of several povidone-iodine (PVP-I) products, a number of other chemical agents, and various physical conditions were evaluated for their ability to inactivate the severe acute respiratory syndrome coronavirus (SARS-CoV). Treatment of SARS-CoV with PVP-I products for 2 min reduced the virus infectivity from 1.17 x 10(6) TCID50/ml to below the detectable level. The efficacy of 70% ethanol was equivalent to that of PVP-I products. Fixation of SARS-CoV-infected Vero E6 cells with a fixative including formalin, glutaraldehyde, methanol, and acetone for 5 min or longer eliminated all infectivity. Heating the virus at 56 degrees C for 5 min dramatically reduced the infectivity of the virus from 2.6 x 10(7) to 40 TCID50/ml, whereas heating the virus for 60 min or longer eliminated all infectivity. Irradiation with ultraviolet light at 134 microW/cm2 for 15 min reduced the infectivity from 3.8 x 10(7) to 180 TCID50/ml; however, prolonged irradiation (60 min) failed to eliminate the remaining virus, leaving 18.8 TCID50/ml. We believe that these findings will be useful for the implementation of infection control measures against SARS, and for the establishment of effective guidelines for the prevention of SARS outbreaks.     

Experimental transmission of ovine herpesvirus-2 in sheep

Transmission of ovine herpesvirus-2 (OvHV-2) in sheep via natural contact and nasal secretions was examined. OvHV-2-free lambs were produced by separating newborn lambs from their mothers within 5 days of birth and raising them in an isolation facility. Transmission experiments via natural contact were conducted by keeping OvHV-2-free lambs with OvHV-2-infected sheep of different ages. Six of the infected ewes in this experiment were pregnant and gave birth during the experimental period. OvHV-2 was not transmitted from the adult sheep, though viral DNA was consistently detected in their peripheral blood leukocytes (PBL). On the other hand, OvHV-2 was transmitted from recently infected lambs to sheep at 10 or 12 weeks after the onset of contact. In addition, we attempted the experimental transmission of OvHV-2 via nasal secretions, by transferring nasal washings from infected sheep to the nostrils of uninfected sheep. Sheep receiving the nasal washings from infected adult sheep maintained their negative status for 15 months, whereas sheep receiving nasal washings from recently infected lambs acquired OvHV-2 by 8 months. The results of these experiments support that OvHV-2 is more easily transmitted to negative sheep by recently infected lambs than by adult sheep. Further, it is supposed that the nasal cavity is a portal for entry and shedding of infectious OvHV-2 in sheep.     

Retrospective seroepidemiological survey for human babesiosis in an area in Japan where a tick-borne disease is endemic

A total of 1,335 archived human sera collected in 1985 from an area in Japan where a tick-borne disease is endemic were examined by indirect immunofluorescence antibody test (IFAT) to estimate seroprevalence against three serologically distinct types of Babesia microti-like parasites; namely, Hobetsu, Kobe, and U.S. types. Eighteen sera (1.3%) were found to be IFAT-positive (titer 1:100-1:6,400), of which 14 and three were ascertained by Western blot analysis to be positive against the Hobetsu and Kobe types, respectively. In addition, four sera showed an IFAT titer of 1:100 against the U.S. type, but they appeared to be false-positive because they were cross-reactive against the Hobetsu and Kobe types, and also because a U.S.-type parasite has not been found in Japan. Our results suggest that human babesiosis in Japan occurred prior to the discovery of the index case in 1999 and that the infections were caused mainly by Hobetsu-type parasites.