First Report of Brown Spot Needle Blight on Pinus thunbergii Caused by Lecanosticta acicola in Korea

Pinus thunbergii Parl., known as black pine, is a pine native to coastal areas of Japan and Korea. Because of its resistance to pollution and salt, it is planted as windbreakers along the coast. In March 2010, needle blight symptoms were found on several trees of black pine in Naju, southern Korea. Further surveys in 2010 and 2011 showed that these symptoms are rather common but disease incidence is less than 1%. Small, circular grayish green spots first appeared on the needles. The spots developed into brown bands reaching 1 to 2 mm long, sometimes with yellow margins. Dark olivaceous to dark grayish stromata were erumpent and conspicuous on the brown lesions in the later stage of disease development. Conidiophores were simple or occasionally branched, 1- to 2-septate, pale brown to olivaceous brown, and smooth walled. Conidia (n = 30) were olivaceous brown to grayish brown, verrucose, thick-walled, mildly curved, allantoid to fusiform, one- to five-septate (mostly three-septate), and 20 to 45 × 3.5 to 5 μm. Morphological characteristics of the fungus were consistent with those of Lecanosticta acicola (Thüm.) Syd. (anamorph of Mycosphaerella dearnessii M.E. Barr), previously known as the causal agent of brown spot needle blight of pines (2,4). The teleomorph was not observed. On potato dextrose agar, single-spore cultures of three isolates were obtained from conidia sporulating on needles. An isolate was preserved at the Korean Agricultural Culture Collection (Accession No. KACC44982). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA) and the complete internal transcribed spacer (ITS) region of rDNA was amplified and sequenced with the primers ITS1/ITS4. The resulting ITS sequence of 543 bp was deposited in GenBank (Accession No. JQ245448). A GenBank BLAST search produced an exact match for the sequences of M. dearnessii (= L. acicola) on P. mugo Tura from Lithuania (HM367708) and P. radiata D. Don from France (GU214663), with 100% sequence similarity. To conduct a pathogenicity test, a conidial suspension (approx. 2 × 10⁵ conidia/ml) was prepared by harvesting conidia from 5-week-old cultures of KACC44982 and sprayed onto the needles of five 3-year-old healthy seedlings. Five noninoculated seedlings of the same age served as controls. Inoculated and noninoculated plants were kept in humid chambers for 48 h in a glasshouse. After 28 days, typical leaf spot symptoms started to develop on the needles of inoculated plants. The fungus, L. acicola, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. The disease has been previously reported on several species of Pinus in the Americas (1) and recently in China (3), Japan (4), and Europe (2). To our knowledge, this is the first report of the Lecanosticta-Pinus association in Korea. Occurrence of the disease in Korea is a new threat to the health of black pine, especially in nursery plots. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.arsgrin.gov/fungaldatabases/ December 2011. (2) L. Jankovsky et al. Plant Protect. Sci. 45:16, 2009. (3) C. Li et al. J. Nanjing Inst. For. 1986:11, 1986. (4) Y. Suto and D. Ougi. Mycoscience 39:319, 1998.

Contrast-enhanced MR cholangiography: comparison of Gd-EOB-DTPA and Mn-DPDP in healthy volunteers

OBJECTIVE

The purpose of this study was to compare the biliary enhancement dynamics of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) and mangafodipir trisodium (Mn-DPDP) for contrast-enhanced MR cholangiography (MRC) in healthy subjects.

METHODS

15 healthy volunteers underwent MRI at 1.5 T with volumetric interpolated breath-hold examination sequence. Each volunteer was scanned once for each contrast agent. The signal-to-noise ratio (SNR) of the liver parenchyma and common hepatic duct (CHD) and the contrast-to-noise ratio (CNR) of CHD to liver parenchyma were evaluated and compared before and at several time points (5, 15, 30, 45, 60, 90, and 120 min) after injection of each agent.

RESULTS

SNR was significantly higher for Gd-EOB-DTPA than for Mn-DPDP in liver parenchyma after 5 min and in CHD after 15 min (p<0.05). CNR of CHD to liver parenchyma using Gd-EOB-DTPA showed an initial decrease at 5 min post-injection followed by a steep increase to a peak at 15 min post-injection. CNR using Mn-DPDP showed a steady increase to a peak at 15 min post-injection without an initial decrease. At 15 min, the value of CNR was significantly higher for Gd-EOB-DTPA than for Mn-DPDP (p<0.05).

CONCLUSION

For both contrast agents, CNR reached a peak at 15 min after contrast injection. At this time point, CNR of Gd-EOB-DTPA was significantly higher than that of Mn-DPDP. Therefore, Gd-EOB-DTPA may provide better contrast-enhanced MRC than Mn-DPDP at 15 min after contrast administration.

Improved electrical and optical properties of ITO/Ag/ITO films by using electron beam irradiation and their application to ultraviolet light-emitting diode as highly transparent p-type electrodes

We have investigated the effect of insertion of a Ag layer in ITO film as well as electron beam irradiation to the multilayer films on the electrical and optical properties of the ITO-based multilayer deposited by magnetron sputtering method at room temperature. Inserting a very thin Ag layer between ITO layers resulted in a significant decrease in sheet resistance and increased the optical band gap of the ITO/Ag/ITO multilayer to 4.35 eV, followed by a high transparency of approximately 80% at a wavelength of 375 nm. We have also fabricated ultraviolet light-emitting diodes (LED) by using the ITO/Ag/ITO p-type electrode with/without electron beam irradiation. The results show that the UV-LEDs having ITO/Ag/ITO p-electrode with electron beam irradiation produced 19% higher optical output power due to the low absorption of light in the p-type electrode.

Failure analysis of InGaN/GaN high power light-emitting diodes fabricated with ITO transparent p-type electrode during accelerated electro-thermal stress

We have investigated the high-temperature degradation of optical power as well as electrical properties of InGaN/GaN light-emitting diodes (LEDs) fabricated with ITO transparent p-electrode during accelerated electro-thermal stress. As the thermal stress increased from 150 degrees C to 250 degrees C at a electrical stress of 200 mA, the optical power of the LEDs was significantly reduced. Degradation of the optical power was thermally activated, with the activation of 0.9 eV. In addition, the activation energy of the degradation of optical power was fairly similar to that of the degradation of series resistance of the LEDs, 1.0 eV, which implies that the increase in the series resistance may result in the severe degradation of optical power. We also showed that the increase in the series resistance of the LEDs during the accelerated electro-thermal stress can be attributed to reduction of the active acceptor concentration in the p-type semiconductor layers and local joule heating due to the current crowding.

First Report of Corynespora Leaf Spot on Ailanthus altissima Caused by Corynespora cassiicola in Korea

Ailanthus altissima (Mill.) Swingle, known as tree-of-heaven, is a deciduous tree belonging to the family Simaroubaceae, which is native to both northeast and central China and Taiwan. The trees often have the ability to replace indigenous plants and disrupt native ecosystems (3). In August 2010, a leaf spot disease was observed on young trees in Yangpyeong, Korea. Field observation in 2010 and 2011 showed that infections are common on 1- or 2-year-old trees. Adult trees were rarely infected. Symptoms usually started at the margin of leaves and expanded into irregular, dark brown leaf spots, eventually causing significant premature defoliation. Representative samples were deposited in the herbarium of Korea University (KUS-F25174 and -F25304). Conidiophores of fungi observed microscopically on the leaf spots were erect, brown to dark brown, single or occasionally in clusters, 80 to 550 × 5 to 8 μm, and mostly arose on the abaxial surface of symptomatic leaves. Conidia were borne singly or in short chains of two to four, ranging from cylindrical to broadest at the base and tapering apically, straight to slightly curved, pale olivaceous brown, 3 to 18 pseudoseptate, 70 to 450 × 8 to 22 μm, each with a conspicuous thickened hilum. On potato dextrose agar, single-spore cultures of five isolates were identified as Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei on the basis of morphological and cultural characteristics (1,4). A monoconidial isolate was preserved at the Korean Agricultural Culture Collection (Accession No. KACC45510). Genomic DNA was extracted with the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced with an ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 548 bp was deposited in GenBank (Accession No. JN974462). The sequence showed >99% similarity (1-bp substitution) with a sequence of C. cassiicola from Ipomoea batatas (GenBank Accession No. FJ852716). To conduct a pathogenicity test, a conidial suspension (~2 × 10⁴ conidia/ml) was prepared by harvesting conidia from 2-week-old cultures of KACC45510 and the suspension sprayed onto the leaves of three healthy seedlings. Three noninoculated seedlings served as control plants. Inoculated and noninoculated plants were kept in humid chambers for 48 h in a glasshouse. After 5 days, typical leaf spot symptoms started to develop on the leaves of all three inoculated plants. C. cassiicola was reisolated from the lesions, confirming Koch's postulates. No symptoms were observed on control plants. C. cassiicola is cosmopolitan with a very wide host range (2). To our knowledge, C. cassiicola has not been reported on A. altissima anywhere in the world. According to field observations in Korea, Corynespora leaf spot was most severe in August and September, especially following a prolonged period of moist weather. C. cassiicola may be a potential biocontrol agent for this highly invasive tree species. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute: Kew, Surrey, England, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA, Retrieved from http://nt.ars-grin.gov/fungaldatabes/ , October 28, 2011. (3) L. B. Knapp and C. D. Canham. J. Torrey Bot. Soc. 127:307, 2000. (4) J. H. Kwon et al. Plant Pathol. J. 17:180, 2001.

First Report of Powdery Mildew Caused by Erysiphe betae on the Invasive Weed Dysphania ambrosioides in Korea

Dysphania ambrosioides (L.) Mosyakin & Clemants (formerly Chenopodium ambrosioides L.), commonly known as epazote, is an herb that is native to Central America, South America, and southern Mexico. As well as in its native areas, it is used as an herb, tea, and food commodity in warm temperate to subtropical areas of Europe, the United States, and Asia. In Korea, however, this plant was accidentally introduced around the 1970s and has become widely naturalized by replacing indigenous plants and disrupting native ecosystems (3). Since 2006, powdery mildew infections of epazote have been consistently found in the southern part of Korea, including Jeju Island. Specimens (n = 8) have been deposited in the Korea University Herbarium (KUS). White mycelial and conidial growth was present mostly on leaf surfaces with sparse growth on young stems and inflorescences. Severely infected leaves were malformed. Slight purplish discoloration was present on the leaves contiguous with colony growth. Mycelial colonies were conspicuous, amphigenous, and epiphytic. Appressoria on the mycelia were lobed. Conidiophores were 110 to 200 μm long and produced conidia singly. Conidia were hyaline, oblong-elliptical, measured 30 to 48 × 13 to 18 μm, lacked fibrosin bodies, and produced germ tubes on the subterminal position. Chasmothecia were amphigenous, scattered or partly clustered, dark brown, spherical, 110 to 130 μm in diameter, and contained four to seven asci. Appendages were mycelioid, numbered 50 to 80 per chasmothecium, 0.5 to 1.5 times as long as the chasmothecial diameter, one- to three-septate, and brown at the base while becoming paler toward the tip. Asci were short stalked, 60 to 75 × 30 to 38 μm, and contained three to five spores. Ascospores were ellipsoid-ovoid with dimensions of 20 to 28 × 14 to 18 μm. On the basis of these morphological features, this fungus was identified as Erysiphe betae (Vanha) Weltzien (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F23213 was amplified with primers ITS5 and P3 and sequenced (4). The resulting sequence of 560 bp was deposited in GenBank (Accession No. JQ041419). A GenBank BLAST search with the current data showed >99% (558 of 560 bp) similarity with the results for E. betae ex Beta vulgaris (sugar beet). Therefore, the sequence analysis verified the pathogen to be E. betae. Previous epazote infections by E. betae have been recorded in Argentina, Mexico, Romania, India, and Japan (1,2). In Taiwan, an epazote powdery mildew associated with Oidium erysiphoides f. sp. chenopodii J.M. Yen, an anamorph of E. betae, was recorded (1,2). To our knowledge, this is the first record of E. betae on epazote in Korea, and the first confirmation of epazote powdery mildew being identified as E. betae on the basis of holomorphic characteristics and ITS rDNA sequences. Our field observation suggests that the powdery mildew is acting as one of several limiting factors to suppress the expansion of this invasive weed in Korea. References: (1) U. Braun. Beih. Nova Hedw. 89:1, 1987. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , November 22, 2011. (3) C. G. Song and Y. H. Yang. The Naturalized Plants in Jeju Island. Nam-Jeju County, Jeju, Korea, 2005. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

Pathological correlation with diffusion restriction on diffusion-weighted imaging in patients with pathological complete response after neoadjuvant chemoradiation therapy for locally advanced rectal cancer: preliminary results

OBJECTIVE

The objective of this study was to assess causative pathological factors associated with diffusion restriction on diffusion-weighted imaging (DWI) in patients who achieved pathological complete response (pCR) after treatment with neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer.

METHODS

In total, 43 patients with locally advanced rectal cancer (≥T3 or lymph node positive) who underwent neoadjuvant CRT, subsequent surgery and ultimately achieved pCR were enrolled. All patients underwent pre- and post-CRT 3.0 T rectal MRI with DWI. Two radiologists blinded to pathological staging reviewed pre- and post-CRT 3.0 T rectal MRI for the presence of diffusion restriction in the corresponding tumour areas on post-CRT DWI, with a third radiologist arbitrating any disagreement. The consensus of these findings was then correlated with pathological data such as intramural mucin and the degree of proctitis and mural fibrosis seen on surgical specimen. Additionally, the pre-CRT tumour volume was measured to define the effect of this variable on the degree of radiation proctitis and fibrosis, as well as the presence of intramural mucin.

RESULTS

Diffusion restriction occurred in 18 subjects (41.9%), while 25 subjects remained diffusion restriction-free (58.1%). The diffusion restriction group tended to have more severe proctitis and mural fibrosis when compared with non-diffusion restriction group (p<0.001). Intramural mucin was also more common in the diffusion restriction group (p=0.052). Higher pre-CRT tumour volumes were significantly predictive of the degree of proctitis (p=0.0247) and fibrosis (p=0.0445), but not the presence of intramural mucin (p=0.0944). Proctitis and mural fibrosis severity were also identified as independent pathological risk factors for diffusion restriction on multivariate analysis (p=0.0073 and 0.0011, respectively).

CONCLUSION

Both radiation-induced proctitis and fibrosis were significant and independent predictors of diffusion restriction in patients achieving pCR after treatment with neoadjuvant CRT for locally advanced rectal cancer, and pre-CRT tumour volume significantly affects both variables.

First Asian Report of Leaf Spot of Ambrosia trifida Caused by Septoria epambrosiae

Ambrosia trifida L., known as giant ragweed, is native to North America and was introduced in Korea in the 1970s (4). It is now widely naturalized, and since 1999, has been designated as one of 11 most 'harmful nonindigenous plants' by the Korean Ministry of Environment because of its adverse effects on native plants. Various strategies to eradicate this noxious weed have been unsuccessful (4). In June 2008, leaf spot symptoms on this weed were found in Inje, Korea. Hundreds of giant ragweed growing along stream banks contained leaf spots with leaf yellowing and premature defoliation. Leaf lesions were 1 to 5 mm in diameter, angular to irregular, dark brown without a distinct margin, later becoming pallid with a brown margin. Between 2008 and 2011, the authors observed the same symptoms in Dongducheon, Yangku, Namyangju, and Pocheon, Korea. Voucher specimens have been housed in the herbarium of Korea University. Numerous black pycnidia were formed on the lesion. Pycnidia were amphigenous, globose, dark brown, ostiolate, and measured 80 to 130 μm in diameter. Conidia were filiform, straight to mildly curved, eguttulate, hyaline, 18 to 36 × 1.5 to 2.5 μm, one to three septate, subtruncate at the base, and tapering to a rounded apex. Single-conidial isolations onto potato dextrose agar formed dark grayish colonies. Pycnidia matured after 5 weeks when plates were incubated under fluorescent illumination for 12-h photoperiods at 25°C. On the basis of morphological and cultural characteristics, the fungus was identified as Septoria epambrosiae D.F. Farr (2). Three isolates were deposited in the Korean Agricultural Culture Collection (KACC). Preliminary morphological identification of the fungal isolates was confirmed by molecular data. The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequences of 449 bp obtained from the three isolates were identical to each other. They showed 100% similarity when compared with a sequence of S. epambrosiae (GenBank No. AF279582). The nucleotide sequence of a representative isolate (KACC43850) was deposited in GenBank (No. JN695498). Pathogenicity was confirmed by inoculating the leaves of three seedlings with a conidial suspension (~2 × 10⁵ conidia/ml). Three noninoculated seedlings served as controls. Plants were maintained in a glasshouse at 100% relative humidity for 48 h. After 6 days, typical leaf spots, identical to the one observed in the field, started to develop on the leaves of the inoculated plants. No symptoms were observed on the control plants. The fungus was successfully reisolated from the symptomatic plants, fulfilling Koch's postulates. A leaf spot disease associated with S. epambrosiae has previously been recorded on A. artemisiifolia in Hungary (1-3) and A. trifida in North America (2,3). To our knowledge, this is the first report of S. epambrosiae on giant ragweed in Asia. Because of its potential as a biocontrol agent, further studies are needed. References: (1) G. Bohar and I. Schwarczinger. Plant Dis. 83:696, 1999. (2) D. F. Farr and L. A. Castlebury. Sydowia 53:81, 2001. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 20, 2011. (4) S. M. Oh et al. Impacts of Invasive Alien Weeds and Control Strategies of Noxious Weeds in Korea. National Institute of Agricultural Science and Technology, Suwon, Korea, 2007.

First Report of Leaf Spot Caused by Ascochyta marginata on Aralia elata in Korea

Aralia elata (Miq.) Seem., known as Japanese angelica tree, is a deciduous shrub belonging to the Araliaceae, which is native to East Asia. The young shoots have long been used in various dishes in East Asia. Commercial cultivation of this shrub, especially in polytunnels, is expanding in Korea. Several diseases including Sclerotinia rot have been known to be present on this plant (1,2). In early September 2007, leaf spot symptoms were first observed on several trees in Hongcheon, Korea. Microscopic observations revealed that the leaf spots were associated with an Ascochyta sp. Further surveys of the Ascochyta leaf spot showed the occurrence of the disease in approximately 5 to 10% of the trees in the 3 ha of commercial fields surveyed in Chuncheon, Gapyeong, Inje, and Jinju, Korea. Initial symptoms on leaves were circular to irregular, brown to dark brown, becoming zonate, and finally fading to grayish brown in the center with a yellow halo. Representative samples were deposited in the herbarium of Korea University. Conidiomata on leaf lesions were pycnidial, amphigenous, but mostly epiphyllous, immersed or semi-immersed in host tissue, light brown to olive brown, and 60 to 200 μm in diameter. Ostioles were papillate, 20 to 35 μm wide, and surrounded by a ring of darker cells. Conidia were hyaline, smooth, cylindrical to clavate, straight to mildly curved, slightly constricted at the septa, medianly one-septate, sometimes aseptate, 8 to 16 × 2.5 to 3.5 μm, and contained small oil drops. These morphological characteristics were consistent with the previous reports of Ascochyta marginata J.J. Davis (3,4). A monoconidial isolate was cultured on potato dextrose agar (PDA) plates and accessioned in the Korea Agricultural Culture Collection (Accession KACC43082). The conidia were readily formed on PDA. Inoculum for the pathogenicity tests was prepared by harvesting conidia from 30-day-old cultures of KACC43082 and a conidial suspension (approximately 2 × 10⁶ conidia/ml) was sprayed onto leaves of three healthy seedlings. Three noninoculated seedlings served as controls. Inoculated and noninoculated plants were covered with plastic bags for 48 h in a glasshouse. After 7 days, typical leaf spot symptoms started to develop on the leaves of the inoculated plants. The fungus, A. marginata, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Japan (4) and China (3). To our knowledge, this is the first report of A. marginata on Japanese angelica trees in Korea. According to our field observations in Korea, the Ascochyta leaf spot mostly occurred on plants growing in a humid environment, especially during the rainy season. The seedlings as well as the trees growing in sunny, well-ventilated plots were nearly free from this disease. Therefore, the growing conditions seemed to be the most important factor for the development and severity of the disease. References: (1) C. K. Lee et al. Plant Pathol. J. 26:426, 2010. (2) S. H. Lee et al. Diseases of Japanese Angelica Tree and Their Control. Research Report 08-10. Korea Forest Research Institute. Seoul, Korea, 2008. (3) J. Sun et al. Acta Mycol. Sin. 14:107, 1995. (4) M. Yoshikawa and T. Yokoyama. Mycoscience 36:67, 1995.

First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Monarda didyma in Korea

Bergamot (Monarda didyma L.), which is native to eastern North America, is an aromatic herb in the family Lamiaceae. It is widely planted in gardens and parks for ornamental purposes and also grown indoors as a fragrant houseplant in Korea. In October 2007, several dozen bergamots planted outdoors in Bonghwa, Korea were found to be heavily infected with a powdery mildew. Symptoms first appeared as thin, white colonies, which subsequently developed into abundant growth on both sides of the leaves. Severe infections often caused leaf distortions and premature senescence. The same symptoms have also been found in bergamot plots in Osan, Suwon, Incheon, and Seoul from 2007 to 2011. Voucher specimens were deposited at Korea University, Seoul, Korea. Hyphae were septate, branched, and 4 to 8 μm wide. Appressoria on the mycelium were nipple shaped. Conidiophores arose from the lateral part of the hyphae, measured 100 to 180 × 10 to 12 μm, were simple, and produced two to four immature conidia in chains, followed by two to three cells. Conidia were hyaline, ellipsoid to barrel shaped, measured 28 to 40 × 16 to 20 μm (length/width ratio = 1.4 to 2.2), lacked distinct fibrosin bodies, and produced germ tubes on the subterminal position, with reticulate wrinkling of the outer walls. No chasmothecia were observed. The structures described above were typical of the Oidium subgenus Reticuloidium anamorph of the genus Golovinomyces, and the fungus measurements were compatible with those of Golovinomyces biocellatus (Ehrenb.) V.P. Heluta as described previously (1,4). The only other powdery mildew known on Monarda spp. is Neoerysiphe galeopsidis (1), which is clearly distinguished by its lobed hyphal appressoria and fine striations on conidial surfaces. To confirm the tentative identification based on morphological characteristics, internal transcribed spacer (ITS) rDNA sequences from two representative isolates (KUS-F23070 and F23117) were obtained using primers ITS5 and P3 as described by Takamatsu et al. (3). The resulting sequences of 523 bp were deposited in GenBank (Accession Nos. JN228358 and JN228359). A GenBank BLAST search produced an exact match for the sequences of G. biocellatus on several plants belonging to the Lamiaceae, with a 100% sequence similarity. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of five healthy potted bergamot plants. Five noninoculated plants served as controls. Plants were maintained in a greenhouse at 25 ± 2°C. Inoculated plants developed signs and symptoms after 6 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. The powdery mildew infections of bergamot plants associated with G. biocellatus have been known in Europe (2) and Japan (4). The current work confirmed the occurrence of G. biocellatus infecting M. didyma in Korea. References: (1) U. Braun. Beih. Nova Hedw. 89:1, 1987. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , July 12, 2011, (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) S. Tanda. J. Agric. Sci. Tokyo Agric. Univ. 47:274, 1997.

Normal mitral cell dendritic development in the setting of Mecp2 mutation

Rett syndrome (RTT) is an autism spectrum disorder caused by mutation in the gene encoding methyl CpG binding protein 2 (MECP2). Evidence to date suggests that these disorders display defects in synaptic organization and plasticity. A hallmark of the pathology in RTT has been identified as decreased dendritic arborization, which has been interpreted to represent abnormal dendritic formation and pruning during development. Our previous studies revealed that olfactory axons display defective pathfinding and targeting in the setting of Mecp2 mutation. In the present work, we use Mecp2 mutant mouse models and the olfactory system to investigate dendritic development. Here, we demonstrate that mitral cell dendritic development proceeds normally in mutant mice, resulting in typical dendritic morphology at early postnatal ages. We also failed to detect abnormalities in dendritic inputs at symptomatic stages when glomeruli from mutant mice appear smaller in area than the wild type (WT) (6 weeks postnatally). Collectively, these findings suggest that the initial defects in glomeruli impairment seen with Mecp2 mutation do not result from abnormal dendritic development. Our results using the olfactory system indicate that dendritic abnormalities are not an early feature in the abnormalities incurred by Mecp2 mutation.

First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Ambrosia trifida in Korea

Ambrosia trifida L., commonly known as giant ragweed, is native to North America and was introduced to Korea in the 1970s (3). It is now widely naturalized, and since 1999, has been designated as one of 11 'harmful nonindigenous plants' by the Korean Ministry of Environment because of its adverse effects on native plants. Various strategies to eradicate this noxious weed have been tried without any success (3). In September 2009, powdery mildew infections of giant ragweed were found for the first time in Dongducheon, Korea, and specimens were isolated and deposited in the Korea University Herbarium (KUS-F24683). White mycelial and conidial growth was present mostly on adaxial leaf surfaces with sparse growth on abaxial leaf sides. Severely infected leaves were malformed. Slight purplish discoloration occurred on the leaves contiguous with colony growth. Mycelial colonies were conspicuous, amphigenous, and epiphytic with indistinct to nipple-shaped appressoria. Conidiophores were 80 to 180 μm long and produced two to five immature conidia in chains. Conidia were ellipsoid or doliiform, 28 to 38 × 16 to 24 μm, and lacked distinct fibrosin bodies. Chasmothecia were amphigenous, scattered or partly clustered, dark brown, spherical, 95 to 130 μm in diameter, and contained 6 to 16 asci. Appendages were mycelioid, numbering 10 to 24 per chasmothecium, 0.5 to 2.5 times as long as the chasmothecial diameter, 1 to 4 septate, and were brown at the base and becoming paler toward the tip. Asci were short stalked, 50 to 75 × 32 to 42 μm and contained two spores. Ascospores were ellipsoid-ovoid with a dimension of 22 to 30 × 15 to 18 μm. On the basis of these morphological characteristics, this fungus was identified as Golovinomyces ambrosiae (Schwein.) U. Braun & R.T.A. Cook (= G. cichoracearum var. latisporus (U. Braun) U. Braun) (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F24683 was amplified with the primers ITS5 and P3 and sequenced (4). The resulting sequence of 508 bp was deposited in GenBank (Accession No. JF907589) and was identical to the ITS sequences of G. ambropsiae on A. artemisiifolia var. elatior from Japan (AB077631) and Korea (JF919680) as well as on A. trifida from the United States (AF011292). Therefore, the sequence analysis verified the pathogen to be G. ambrosiae. To our knowledge, this is the first record of powdery mildew infections on giant ragweed outside of North America (2). Although the disease incidence is still low, the disease could be a limiting factor to suppress the expansion of this noxious weed in Korea. References: (1) U. Braun and R. T. A. Cook. Mycol. Res. 113:616, 2009. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , May 5, 2011. (3) S. M. Oh et al. Impacts of Invasive Alien Weeds and Control Strategies of Noxious Weeds in Korea. National Institute of Agricultural Science and Technology, Suwon, Korea, 2007. (4) S. Takamatsu et al. Mycol. Res. 111:117, 2009.

Predicting complete loss to follow-up after a health-education program: number of absences and face-to-face contact with a researcher

Background

Research on health-education programs requires longitudinal data. Loss to follow-up can lead to imprecision and bias, and complete loss to follow-up is particularly damaging. If that loss is predictable, then efforts to prevent it can be focused on those program participants who are at the highest risk. We identified predictors of complete loss to follow-up in a longitudinal cohort study.

Methods

Data were collected over 1 year in a study of adults with chronic illnesses who were in a program to learn self-management skills. Following baseline measurements, the program had one group-discussion session each week for six weeks. Follow-up questionnaires were sent 3, 6, and 12 months after the baseline measurement. A person was classified as completely lost to follow-up if none of those three follow-up questionnaires had been returned by two months after the last one was sent.

We tested two hypotheses: that complete loss to follow-up was directly associated with the number of absences from the program sessions, and that it was less common among people who had had face-to-face contact with one of the researchers. We also tested predictors of data loss identified previously and examined associations with specific diagnoses.

Using the unpaired t-test, the U test, Fisher's exact test, and logistic regression, we identified good predictors of complete loss to follow-up.

Results

The prevalence of complete loss to follow-up was 12.2% (50/409). Complete loss to follow-up was directly related to the number of absences (odds ratio; 95% confidence interval: 1.78; 1.49-2.12), and it was inversely related to age (0.97; 0.95-0.99). Complete loss to follow-up was less common among people who had met one of the researchers (0.51; 0.28-0.95) and among those with connective tissue disease (0.29; 0.09-0.98). For the multivariate logistic model the area under the ROC curve was 0.77.

Conclusions

Complete loss to follow-up after this health-education program can be predicted to some extent from data that are easy to collect (age, number of absences, and diagnosis). Also, face-to-face contact with a researcher deserves further study as a way of increasing participation in follow-up, and health-education programs should include it.

Altered expression of costimulatory molecules in Behçet's disease according to clinical activity

BACKGROUND

The reduced expression of molecules limiting excessive immune responses has been considered a pathogenic mechanism associated with autoimmune diseases.

OBJECTIVES

To understand the implications of costimulatory molecules in Behçet's disease (BD), the expression of CTLA-4 and PD-1 on T-cell subsets and of their ligands CD80, CD86 and PD-L1 on antigen-presenting cells (APCs) was investigated.

METHODS

Peripheral blood mononuclear cells (PBMC) from 11 patients with active BD, eight patients with inactive BD, eight patients with recurrent aphthous ulcers and 10 healthy volunteers as healthy controls (HC) were stimulated with phorbol myristate acetate and ionomycin. The expression of costimulatory molecules was then analysed by flow cytometry. Soluble CTLA-4 (sCTLA-4) concentrations were determined by enzyme-linked immunosorbent assay and the transcript level of PD-L1 was measured by real-time polymerase chain reaction. The PD-L1 expression in skin lesions of patients with BD was evaluated by immunohistochemistry.

RESULTS

Compared with the HC group, reduced expression of CTLA-4 in CD4+ T cells after stimulation was observed in the active BD group, with no difference in the production of sCTLA-4. CD86 expression, in the resting APCs, was reduced in the active BD group compared with the HC group. PD-L1 expression in the APCs was decreased in the active BD group with or without stimulation of cells. Concordantly, the mRNA levels of PD-L1 in PBMC, and PD-L1 expression in the cutaneous lesions, were low in the active BD group.

CONCLUSIONS

The results of this study suggest that altered expression of PD-L1, CTLA-4 and CD86 may be involved in the pathogenesis of BD.

Health care services and the transition to young adulthood: challenges and opportunities

OBJECTIVE

The aim of this study was to examine the potential role of the health care system in the successful transition to young adulthood for all adolescents, with emphasis on adolescents with special health care needs (ASHCN), and to evaluate the system's status in filling that role.

METHOD

Research and conceptual frameworks addressing successful transitions and functioning were reviewed. A framework describing a role for health care services in the transition was presented. The health care system's status in promoting healthy transitions was evaluated, including National Survey of Children with Special Health Care Needs 2005-2006 analyses of key outcomes for ASHCN.

RESULTS

Although most national efforts to define skills needed for the transition have focused on career/vocational skills, a few frameworks integrate broader issues such as health, psychosocial development, and civic engagement. Adolescent transitional issues have generally received little attention; however, these have been articulated for ASHCN. Nevertheless, only 2 in 5 ASHCN receive transitional care, and ASHCN fare poorly on other core outcomes. ASHCN with mental health conditions fare worse on outcomes than those with physical health conditions. Our framework for healthy transitions includes the following: 1) adolescents can access a comprehensive health care system, 2) preventable problems are avoided, and 3) chronic problems are managed. The present health care system falls short of accomplishing these.

CONCLUSIONS

Health care services can potentially play a role in facilitating a healthy transition to young adulthood; however, many gaps exist. Although the health care reform act addresses some gaps, efforts that integrate adolescents' developmental needs and address mental health issues are needed.

The relationship between stress positions and pain intensity in triangular fibrocartilage lesions

We investigated the relationship between stress applied in several positions of the wrist and pain intensity in triangular fibrocartilage lesions in sixty-one patients who were diagnosed as having triangular fibrocartilage lesions and had a wrist arthroscopy. Before arthroscopy, we stressed the wrist with an axial load applied in four different wrist positions, and the evoked pain was graded into four levels. The patients who had a triangular fibrocartilage lesion on arthroscopy were divided into those with a traumatic tear and those with degenerative changes. While hypersupination and extension of wrist position evoked the most severe pain in patients with a traumatic tear, the intensity of pain did not relate to wrist rotation in patients with degenerative changes.

To tweet, or not to tweet: gender differences and potential positive and negative health outcomes of adolescents' social internet use

Adolescents and young adults are avid Internet users. Online social media, such as social networking sites (e.g., Facebook, MySpace), blogs, status updating sites (e.g., Twitter) and chat rooms, have become integral parts of adolescents' and young adults' lives. Adolescents are even beginning to enter the world of online dating with several websites dedicated to "teenage online dating." This paper reviews recent peer-reviewed literature and national data on 1) adolescents use of online social media, 2) gender differences in online social media and 3) potential positive and negative health outcomes from adolescents' online social media use. We also examine parental monitoring of adolescents' online activities. Given that parental supervision is a key protective factor against adolescent risk-taking behavior, it is reasonable to hypothesize that unmonitored Internet use may place adolescents' at significant risk, such as cyberbullying, unwanted exposure to pornography, and potentially revealing personal information to sexual predators.

Rapid method for direct extraction of mRNA from seeded soils

A protocol for direct extraction of mRNA from soil samples was developed. Soil samples (10 g) were washed twice with 120 mM phosphate buffer (pH 5.2). The lysis of cells, fixation of RNA, and hydrolysis of DNA were achieved by vigorously shaking the washed soil in a 4 M guanidine thiocyanate solution containing 25 mM sodium citrate, 0.5% sarcosyl, and 0.1 M 2-mercaptoethanol. The pH of the homogenized mixture was adjusted with 2 M sodium acetate (pH 4.0); the mRNA was then extracted with phenol and chloroform. Total RNA was precipitated with isopropanol. This method extracts up to 17 mug of total RNA per g (wet weight) of soil containing 8.0 x 10 cells of Pseudomonas aeruginosa PU21, and mRNA has been detected in 160-ng total RNA fractions. This method has been used for the detection of mRNA transcribed from specific biodegradative genes, including the nah and mer operons, in contaminated soils. This extraction method can be completed within a few hours and has tremendous potential for ecological studies of in situ gene expression among soil microbiotas.

Who gets confidential care? Disparities in a national sample of adolescents

Using the 2001-2004 Medical Expenditures Panel Survey, we examined rates of past-year adolescent time alone with a clinician by visit type, and among youths with a preventive visit, examined age, gender, and race/ethnicity differences. Youths with a preventive visit have higher rates of time alone; rates for these youths increase with age, are higher for males (42%) versus females (37%), and are lowest among Hispanics. Time alone rates are low, especially for younger females and Hispanic youths. Special efforts are needed to increase time alone in these populations.

Neurological deficit after surgical enucleation of schwannomas of the upper limb

We evaluated 56 patients for neurological deficit after enucleation of a histopathologically confirmed schwannoma of the upper limb. Immediately after the operation, 41 patients (73.2%) had developed a new neurological deficit: ten of these had a major deficit such as severe motor or sensory loss, or intolerable neuropathic pain. The mean tumour size had been significantly larger in patients with a major neurological deficit than in those with a minor or no deficit. After a mean 25.4 months (12 to 85), 39 patients (70%) had no residual neurological deficit, and the other 17 (30%) had only hypoaesthesia, paraesthesiae or mild motor weakness. This study suggests that a schwannoma in the upper limb can be removed with an acceptable risk of injury to the nerve, although a transient neurological deficit occurs regularly after the operation. Biopsy is not advised. Patients should be informed pre-operatively about the possibility of damage to the nerve: meticulous dissection is required to minimise this.

Helping young men thrive: positive youth development and men's health

Positive youth development (PYD) is a strong and growing field that complements the traditional problem-focused view of youth, and describes and promotes the healthy development and positive outcomes of young people. The PYD perspective can be applied in clinical and community intervention settings. Frameworks such as the "Five Cs" and the Search Institute's developmental assets model have guided researchers and practitioners in better understanding the process of PYD and the effectiveness of community interventions to promote PYD. The PYD literature lacks a coherent guiding framework to describe gender differences in positive development, which in turn could guide community and clinical interventions designed to help young men thrive.

Marijuana: use among young males and health outcomes

Marijuana is the most commonly used illicit drug by adolescents and young adults, with more males than females reporting marijuana use. The adolescent and young adult years represent a critical period for interventions to prevent marijuana use and abuse. This article reviews relevant literature, including trends in young males' marijuana use and health effects of marijuana use. By most measures, there has been little net change in marijuana use among 12th graders and young adults since the 1990s. Despite males' greater use, little research has examined gender differences in areas such as metabolism of marijuana and long-term impact of marijuana use. In many areas, including dental health, fertility, and respiratory function, research is either sparse or has yielded conflicting results. Similarly, research on marijuana's carcinogenic effects has yielded conflicting results; however, a small but consistent literature indicates that marijuana use is linked to cancers unique to males. A stronger literature has identified an association between marijuana use and psychiatric problems. Clinical and program interventions for adolescents have potential to prevent marijuana use, as well as screen for and treat marijuana abuse. Improved research is needed, such as research with greater consistency in defining levels of use and greater emphasis on gender differences. Such research would help clinical and program interventions focus on those most at risk for adverse outcomes.

Trends in adolescent and young adult health in the United States

This review presents a national health profile of adolescents and young adults (ages 10-24). The data presented include trends on demographics, mortality, health-related behaviors, and healthcare access and utilization, as well as the most significant gender and racial/ethnic disparities. Although the data show some improvement, many concerns remain. Encouraging trends-such as decreases in rates of homicide, suicide, and some measures of reproductive health-appear to be leveling off or, in some cases, reversing (e.g., birth and gonorrhea rates). Large disparities, particularly by race/ethnicity and gender, persist in many areas. Access to quality healthcare services remains a challenge, especially during young adulthood. Policy and research recommendations to improve health during these critical periods in the lifespan are outlined.