bluuebunny/crossref_metadata_2025 huggingface dataset:
Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia
Authors: Rodríguez Edna , Valbuena Martha Cecilia , Rey Maritza , Porras de Quintana Luisa
Published: July 2006

Objective: To describe and identify the photoallergens causing photoallergic contact dermatitis in the population attending the outpatient clinic of the Centro Dermatologico Federico Lleras Acosta (CDFLLA), the National Institute of Dermatology of Colombia.

Materials and methods: Eighty‐two patients with clinical diagnosis of photoallergic contact dermatitis enter the study. These patients attended the CDFLLA between August 2001 and May 2003. Photopatch tests were performed using the standard series of sunscreens (Chemotechnique Diagnostics) and 6‐methylcoumarin. Cetyl alcohol, phenoxyethanol, methylparabene, propylene glycol, triethanolamine, propylparabene, trichlorocarbanilide and dichromate were also included. The allergens were applied in duplicate on the healthy skin of the back and covered with opaque tape withdrawn 24 h later, the panel on the right was irradiated with an ultraviolet A dose of 5 J/cm2. The tests were read 24 h after the application of the allergens, 24 and 72 h post‐irradiation. The readings were assessed according to the visual scoring system recommended by the International Contact Dermatitis Research Group.

Results: Twenty‐six patients (31.7%) showed positive photopatch test responses to one or several allergens. Four of them showed positive results to three components of the series and four patients to two components. Thirty‐eight photoallergic and 18 allergic reactions were observed. Ultraviolet filters were the substances which more frequently produced positive photopatch test responses (30.5%). The most common ultraviolet filter photoallergen was benzophenone‐3 with 22/82 positive results (26.8%), followed by octyl methoxycinnamate (8/82), benzophenone‐4 and mexenone (2/82), phenylbenzimidazole sulphonic acid, methylbenziliden camphor and octyl dimethyl PABA (1/82). One patient showed a photoallergic response to 6‐methylcoumarin. There was a concordance between the allergen which elicited the positive response and the use of different substances which contained that molecule among its compounds in 17 patients (65.3%). 19.5% of the patients (16/82) showed positive results to one or several allergens in the irradiated panel as well as in the unirradiated control site. These cases were diagnosed as contact allergy, probably caused by aeroallergens, presenting a natural history and a clinical picture similar to photocontact allergy. The most common allergen was dichromate with 10 positive results.

Conclusions: The results of this study confirm that sunscreens are the more frequently involved substances in photoallergic contact dermatitis in our population. Identification of the photoallergen is the key element for adequate disease control and patient education.
Characteristics of diagnosed polymorphous light eruption
Authors: Naleway Allison L. , Greenlee Robert T. , Melski John W.
Published: July 2006

Background: The characteristics of polymorphous light eruption (PMLE) have been described in patients evaluated and diagnosed at specialized photodermatology centers. Our goal was to describe the characteristics of PMLE diagnosed in a general clinic setting.

Methods: We used electronic medical records to identify patients diagnosed with PMLE from 2000 to 2002 within a large group practice. We then collected additional information from medical records about patient demographics, lesion morphology, diagnostic testing, and therapies for the selected patients.

Results: We identified 142 patients with diagnosed PMLE. After manual chart review, we excluded 18 patients with other forms of photosensitivity, eczema, or collagen vascular disease. Eighty‐percent of the remaining 124 patients were diagnosed by a dermatologist during the study period. Females predominated in our patient series and the mean age of PMLE onset was 37.8 years. Lesions were commonly described as papular, edematous papulare, papulo‐vesicular, eczematous, and plaque‐like. Few skin biopsies were performed, and no patient had phototesting or photopatch testing. Topical corticosteroids and antihistamines were the most commonly prescribed therapies. Only four patients were treated with phototherapy.

Conclusions: Patient demographics and lesion morphology in our cohort were similar to other reports, but patterns of diagnostic testing and treatment were somewhat different than those observed in photodermatology clinics.
GSTM1 and GSTT1 null genotypes as possible heritable factors of rosacea
Authors: Yazici Ayca Cordan , Tamer Lulufer , Ikizoglu Guliz , Kaya Tamer Irfan , Api Hale , Yildirim Hatice , Adiguzel Aynur
Published: July 2006

Purpose: Rosacea might be related to an increased activity of reactive oxygen species (ROS) and deficient function of the antioxidant system. Glutathione S‐transferases (GSTs) play a primer role in cellular defense against electrophilic chemical species and radical oxygen species. We hypothesized that increased ROS activity or decreased antioxidant potential, possibly induced by GST gene polymorphism, might have a pathogenic role in rosacea.

Methods: The study group consisted of 45 patients with rosacea and 100 control subjects. DNA samples were isolated from blood samples using high pure polymerase chain reaction (PCR) Template preparation Kit. The GSTM1, GSTT1, and P1 polymorphisms were detected using a real‐time PCR and fluorescence resonance energy transfer with a Light‐Cycler Instrument. Associations between specific genotypes and the development of rosacea were examined using logistic regression analyses to calculate odds ratios (OR) and 95% confidence intervals (CI).

Results: GSTM1 and GSTT1 null genotypes were found to be statistically different from control (P=0.005, P=0.009, respectively), and associated with an increased risk of rosacea (OR [95% CI]: 2.84 [1.37–5.89]; OR [95% CI]: 2.68 [1.27–5.67], respectively). There was a statistically significant relationship between both null combination of the GSTM1 and GSTT1 genotype polymorphisms and rosacea (P=0.003, OR [95% CI]: 4.18 [1.57–11.13]). There were no statistically significant differences between patient and control groups for the GSTP1 Ile/Ile, Ile/Val, and Val/Val genotypes (P>0.05).

Conclusion: We demonstrated a significant association between the GSTT1 and/or GSTM1 null genotypes and rosacea. However, the potential role of GSTs as markers of susceptibility to rosacea needs further studies in larger patient groups.
Keratoacanthoma in vitiligo lesion after UVB narrowband phototherapy
Authors: Brazzelli V. , Barbagallo T. , Prestinari F. , Vassallo C. , Agozzino M. , Vailati F. , Cespa M. , Borroni G.
Published: July 2006

The treatment of vitiligo is still a challenge. Among various therapeutic modalities, phototherapy with UVB narrowband (UVB‐NB) is presently considered a treatment of choice for this skin disease.

The exact skin cancer risk deriving from UVB‐NB is a serious concern to be determined.

We report a case of keratoacanthoma developed in the vitiligo area during a prolonged course of UVB‐NB therapy.
Skin phototyping in a Chinese female population: analysis of four hundred and four cases from four major cities of China
Authors: Liu W. , Lai W. , Wang X. M. , Li L. , Tian Y. , Lu Y. , Wu Y. Y. , Li Y. , Zhang P. , Wu Y. , Chen L.
Published: July 2006

Background/purpose: The sun‐reactive skin types in 404 Chinese females living in different cities were investigated in this study.

Methods: A questionnaire was designed according to the original concept of skin types proposed by Fitzpatrick and the investigation was conducted in two ways: self‐administered reporting and then a personal interview. Minimal erythema dose (MED) and minimal persistent pigmentation dose (MPPD) were also measured in part of the volunteers with a standard solar simulator.

Results: The results show that in the way of personal interview, the predominant skin type of the investigated group is type III (71.4%), and then type II (14.7%) and type IV (14.2%), while in the self‐reporting manner, the result is as follows: type III, 74.3%, type II, 25.6% and type IV, 1%. There are no skin type I, V or VI in the studied group. MED and MPPD from the same population show some relevance to the skin types, e.g. with the change of skin type from Type II to IV, the mean value of MED increases gradually and the MPPD decreases slightly.

Conclusions: From the studyn we concluded that the skin types of the investigated Chinese females are principally type III (more than 70%), and then type II and type IV. The different ways of answering the questionnaire did not affect the results remarkably. The measurements of photobiology parameters confirmed that there is a certain correlation between skin types and MED or MPPD determined in this group of volunteers.
Melanin differentially protects from the initiation and progression of threshold UV‐induced erythema depending on UV waveband
Authors: Phan Tai A. , Halliday Gary M. , Barnetson Ross StC. , Damian Diona L.
Published: July 2006

Background/purpose: This study aimed to determine the relationship between various measures of constitutive skin pigmentation and erythema caused by solar‐simulated UV (ssUV), 290 and 310 nm UV.

Methods: Skin pigmentation was assessed clinically by skin typing as well as objectively by measurement of the melanin index (MI) by reflectance spectroscopy. Subjects having Fitzpatrick skin types I–IV were exposed to graded doses of ssUV and either narrowband 310 nm (n=70) or 290 nm (n=69) UV, and assessed 24 h after exposure. Minimal erythema dose (MED) was assessed visually as the lowest dose that caused minimally perceptible erythema. Susceptibility to further development of erythema with higher exposure doses was measured by the gradient of erythema dose–response curves. This was determined by linear regression using reflectance spectrometry data beyond the MED.

Results: Although there was considerable variation within each skin type, MI and ssUV MED increased with increasing Fitzpatrick skin type. MI correlated with ssUV MED and 310 nm UV MED, but not 290 nm UV MED. There was also a significant negative correlation between MI and erythema dose–response gradients caused by ssUV, 310 and 290 nm UV.

Conclusion: Melanin situated near the basal epidermis may not protect from the initial development of threshold erythema caused by 290 nm UV because it penetrates poorly past the stratum corneum and is not well absorbed by melanin in vivo compared with 310 nm UV. Higher erythemal 290 nm UV doses may reach basal epidermal melanin, which may then afford protection against further 290 nm UV erythema.
Ultraviolet A in vitiligo
Authors: El‐Mofty Medhat , Mostafa Wedad , Youssef Randa , El‐Fangary Mona , Elramly Amany Z. , Mahgoub Doaa , Fawzy Marwa
Published: July 2006

Both types of Ultraviolet (UV), UVB (290–320 nm) and UVA (320–400 nm), produce increased pigmentation or tanning. However, no evaluation of UVA alone in the treatment of vitiligo has been reported. Therefore, it was the purpose of this work to study the pigmentogenic effect of UVA (5 and 15 J/cm2) in vitiligo. The study included 20 randomly selected patients with vitiligo involving more than 30% of the body surface area with a bilateral/symmetrical distribution. They were equally divided into two groups each of 10 patients. All patients received three weekly sessions of UVA, 15 J/cm2 in group I and 5 J/cm2 in group II, a total of 48 sessions over 16 weeks. Overall pigmentation of 60% and above was recorded in 50% and 10% of patients in groups I and II, respectively. We conclude that broadband UVA alone, without psoralens, and in appropriate doses may be of important therapeutic value in vitiligo.
Effective treatment of scalp psoriasis using the excimer (308 nm) laser
Authors: Morison Warwick L. , Atkinson Darleen F. , Werthman Lucille
Published: July 2006

Background: Psoriasis of the scalp can be a major therapeutic challenge as response to topical medication is often inadequate. The excimer laser has potential for providing local phototherapy as its high irradiance makes treatment at this site a practical option.

Objectives: To analyze retrospectively results of treating scalp psoriasis with the excimer (308 nm) laser.

Methods: Thirty‐five patients were treated and all had failed intensive topical therapy. Manual separation of hair was used to provide access to the treatment site. Starting doses ranged from 300 mJ/cm2 (type I) to 1000 mJ/cm2 (type IV) with treatment twice weekly.

Results: All patients improved. Seventeen/35 (49%) of patients cleared>95% (mean: 21 treatments; range: 6–52) and 16/35 (45%) cleared 50–95%. Phototoxicity in the form of erythema and blistering occurred in all patients, particularly around the ears and nape of neck.

Conclusion: The excimer laser is a successful approach to treatment of psoriasis of the scalp being a simple treatment that can be performed in a short period of time and which has a high rate of effectiveness.
Depletion of Sphingolipids Facilitates Endosome to Golgi Transport of Ricin
Authors: Grimmer Stine , Spilsberg Bjørn , Hanada Kentaro , Sandvig Kirsten
Published: July 2006

It has been previously demonstrated that depletion of cholesterol inhibits endosome to Golgi transport. Whether this inhibition is due to disruption of sphingolipid‐ and cholesterol‐containing lipid rafts that are selected for Golgi transport or whether there is a physical requirement of cholesterol for either membrane deformations, facilitating formation of transport vesicles, or for recruitment of cytosolic constituents is not obvious. To investigate this in more detail, we have studied endosome to Golgi transport of ricin in sphingolipid‐deficient cells using either a mutant cell line that does not express serine palmitoyltransferase, the first enzyme in sphingolipid biosynthesis, or a specific inhibitor, myriocin, of the same enzyme. Depletion of sphingolipids gave an increased sensitivity to ricin, and this increased sensitivity was inhibited by addition of sphingolipids. Importantly, endosome to Golgi transport of ricin, measured as sulfation of a modified ricin molecule, was increased in sphingolipid‐deficient cells. No effect was seen on other pathways taken by ricin. Interestingly, cholesterol depletion inhibited endosome to Golgi transport even in cells with reduced levels of sphingolipids, suggesting that cholesterol as such is required for formation of transport vesicles. Our results indicate that the presence of sphingolipids actually limits and may function to control endosome to Golgi transport of ricin.
Cytokines Regulate Matrix Metalloproteinases in Human Uterine Endometrial Fibroblast Cells Through a Mechanism That Does Not Involve Increases in Extracellular Matrix Metalloproteinase Inducer
Authors: Braundmeier Andrea G. , Nowak Romana A.
Published: July 2006

Problem  Endometriosis is the presence of ectopic uterine endometrial tissue in the peritoneal cavity. Peritoneal fluid samples of women with endometriosis show elevated interleukin‐1 (IL‐1)β, tumor necrosis factor (TNF)‐α and transforming growth factor (TGF)‐β1 levels, indicating that an altered immune system may play an important role in the pathogenesis of endometriosis. The invasion of ectopic endometrium into peritoneal mesothelium requires matrix metalloproteinases (MMPs) for tissue remodeling. Several MMPs are differentially expressed in human uterine endometrium with menstrual endometrium showing the highest level of expression. MMPs are stimulated by cytokines and also by the protein Extracellular Matrix Metalloproteinase Inducer (EMMPRIN).

Method of Study  To determine the role of cytokines in ectopic endometrial invasion, we investigated whether cytokines could regulate MMP production by endometrial fibroblast cells and whether this stimulation occurred through an effect on EMMPRIN expression. Human uterine fibroblasts (HUF) were treated with IL‐1β, TGF‐β1 and TNF‐α in a dose dependent and time dependent manner (C, 0.1, 1, 10 ng/mL IL‐1β or TGF‐β1; C, 2, 10, 50 ng/mL TNF‐α) for 0, 6, 12, and 24 hr. Cell conditioned medium samples were collected and concentrated at each timepoint for immunoblot analysis. Cellular RNA was collected for real time PCR analysis of MMPs‐1, ‐2, ‐3 and EMMPRIN mRNA levels.

Results  Our results showed that IL‐1β stimulated MMP‐1 protein secretion and mRNA levels in a time dependent manner (P < 0.05), MMP‐2 mRNA in a time dependent manner and MMP‐3 in a time and dose dependent manner. TNF‐α stimulated MMP‐1 and ‐3 protein secretion in a time dependent manner and stimulated MMP‐1, ‐2 and ‐3 mRNA levels in a time dependent manner (P < 0.05). Neither IL‐1β nor TNF‐α treatment affected MMP‐2 protein secretion. TGF‐β1 inhibited MMP‐1 and MMP‐2 mRNAs at the highest treatment dose after 24 hr but there was no effect on protein secretion. TGF‐β1 exerted no effect on MMP‐3 mRNA or protein secretion (P < 0.05). Neither of the cytokines affected EMMPRIN protein or mRNA levels but the 10 ng/mL TGF‐β1 treatment did cause a reduction in EMMPRIN mRNA levels.

Conclusions  These data show that elevated cytokines may play a role in the establishment of ectopic endometrium in the peritoneal cavity by stimulating MMPs to remodel the mesothelial lining of the peritoneum thus allowing for tissue invasion. The stimulation of MMPs by cytokines occurred without any change in EMMPRIN expression whereas the inhibitory effect of TGF‐β1 involved a reduction in EMMPRIN mRNA levels.
Effect of the BDNF V166M polymorphism on working memory in healthy adolescents
Authors: Hansell N. K. , James M. R. , Duffy D. L. , Birley A. J. , Luciano M. , Geffen G. M. , Wright M. J. , Montgomery G. W. , Martin N. G.
Published: July 2006

Brain‐derived neurotrophic factor (BDNF) may play a role in modulating memory function and there is growing evidence that the BDNF V166M polymorphism may influence episodic memory in humans. However, previous association studies examining this polymorphism and working memory are inconsistent. The current study examined this association in a large sample of adolescent twin‐pairs and siblings (785 individuals from 439 families). A range of measures (event‐related potential, general performance and reaction time) was obtained from a delayed‐response working‐memory task and total association was examined using the quantitative transmission disequilibrium tests (QTDT) program. Analyses had approximately 93–97% power (α= 0.05) to detect an association accounting for as little as 2% of the variance in the phenotypes examined. Results indicated that the BDNF V166M polymorphism is not associated with variation in working memory in healthy adolescents.
Evidence for abnormal early development in a mouse model of Rett syndrome
Authors: Santos M. , Silva‐Fernandes A. , Oliveira P. , Sousa Nuno , Maciel Patrícia
Published: July 2006

Rett syndrome (RTT) is a neurodevelopmental disorder that affects mainly females, associated in most cases to mutations in theMECP2gene. After an apparently normal prenatal and perinatal period, patients display an arrest in growth and in psychomotor development, with autistic behaviour, hand stereotypies and mental retardation. Despite this classical description, researchers always questioned whether RTT patients did have subtle manifestations soon after birth. This issue was recently brought to light by several studies using different approaches that revealed abnormalities in the early development of RTT patients. Our hypothesis was that, in the mouse models of RTT as in patients, early neurodevelopment might be abnormal, but in a subtle manner, given the first descriptions of these models as initially normal. To address this issue, we performed a postnatal neurodevelopmental study in theMecp2tm1.1Birdmouse. These animals are born healthy, and overt symptoms start to establish a few weeks later, including features of neurological disorder (tremors, hind limb clasping, weight loss). Different maturational parameters and neurological reflexes were analysed in the pre‐weaning period in theMecp2‐mutant mice and compared to wild‐type littermate controls. We found subtle but significant sex‐dependent differences between mutant and wild‐type animals, namely a delay in the acquisition of the surface and postural reflexes, and impaired growth maturation. The mutant animals also show altered negative geotaxis and wire suspension behaviours, which may be early manifestations of later neurological symptoms. In the post‐weaning period the juvenile mice presented hypoactivity that was probably the result of motor impairments. The early anomalies identified in this model of RTT mimic the early motor abnormalities reported in the RTT patients, making this a good model for the study of the early disease process.
Growth hormone/JAK‐STAT axis signal‐transduction defect
Authors: Rojas‐Gil Andrea P. , Ziros Panos G. , Diaz Leonor , Kletsas Dimitris , Basdra Efthimia K. , Alexandrides Theodore K. , Zadik Zvi , Frank Stuart J. , Papathanassopoulou Vassiliki , Beratis Nicholas G. , Papavassiliou Athanasios G. , Spiliotis Bessie E.
Published: July 2006

Primary cultured fibroblasts of four patients with idiopathic short stature and severe growth delay, which displayed normal growth hormone receptor expression presented a reduced ability for activation of signal transducer and activator of transcription‐3 (STAT3). Impaired STAT3 activation was accompanied by cell‐cycle arrest at the Go /G1 phase. Increased levels of the cyclin‐dependent kinase inhibitor, p21WAF/CIPI, and reduced levels of cyclins were also detected in these patients. High concentrations of human growth hormone (1000 ng·mL−1) added to the culture medium induced activation of STAT3 and reduced the levels of p21WAF/CIPI in the fibroblasts of the four idiopathic short stature children. Treatment of these children with exogenous human growth hormone significantly augmented their growth velocity. Overall, our study provides the first evidence linking the idiopathic short stature phenotype with a functional aberration in the growth hormone signal transduction cascade which can be successfully overcome by exposure to high doses of growth hormone.
Calpain 3: a key regulator of the sarcomere?
Authors: Duguez Stéphanie , Bartoli Marc , Richard Isabelle
Published: July 2006

Calpain 3 is a 94‐kDa calcium‐dependent cysteine protease mainly expressed in skeletal muscle. In this tissue, it localizes at several regions of the sarcomere through binding to the giant protein, titin. Loss‐of‐function mutations in the calpain 3 gene have been associated with limb‐girdle muscular dystrophy type 2A (LGMD2A), a common form of muscular dystrophy found world wide. Recently, significant progress has been made in understanding the mode of regulation and the possible function of calpain 3 in muscle. It is now well accepted that it has an unusual zymogenic activation and that cytoskeletal proteins are one class of its substrates. Through the absence of cleavage of these substrates, calpain 3 deficiency leads to abnormal sarcomeres, impairment of muscle contractile capacity, and death of the muscle fibers. These data indicate a role for calpain 3 as a chef d'orchestre in sarcomere remodeling and suggest a new category of LGMD2 pathological mechanisms.
Implication of calpain in neuronal apoptosis
Authors: Raynaud F. , Marcilhac A.
Published: July 2006

Apoptotic neuronal cell death is the cardinal feature of aging and neurodegenerative diseases, but its mechanisms remain obscure. Caspases, members of the cysteine protease family, are known to be critical effectors in central nervous system cellular apoptosis. More recently, the calcium‐dependent proteases, calpains, have been implicated in cellular apoptotic processes. Indeed, several members of the Bcl‐2 family of cell death regulators, nuclear transcription factors (p53) and caspases themselves are processed by calpains. Progressive regional loss of neurons underlies the irreversible pathogenesis of various neurodegenerative diseases such as Alzheimer's disease in adult brain. Alzheimer's disease is characterized by extracellular plaques of amyloid–β peptide aggregates and intracellular neurofibrillary tangles composed of hyperphosphorylated tau leading to apoptotic cell death. In this review, we summarize the arguments showing that calpains modulate processes that govern the function and metabolism of these two key proteins in the pathogenesis of Alzheimer's disease. To conclude, this article reviews our understanding of calpain‐dependent apoptotic neuronal cell death and the ability of these proteases to regulate intracellular signaling pathways leading to chronic neurodegenerative disorders such as Alzheimer's disease. Further research on these calpain‐dependent mechanisms which promote or prevent cell apoptosis should help us to develop new approaches for preventing and treating neurodegenerative disorders.
Adipophilin increases triglyceride storage in human macrophages by stimulation of biosynthesis and inhibition of β‐oxidation
Authors: Larigauderie Guilhem , Cuaz‐Pérolin Clarisse , Younes Amena B. , Furman Christophe , Lasselin Catherine , Copin Corinne , Jaye Michael , Fruchart Jean‐Charles , Rouis Mustapha
Published: July 2006

Lipid accumulation alters macrophage biology and contributes to lipid retention within the vessel wall. In this study, we investigated the role of adipophilin on triglyceride accumulation and lipid‐droplet formation in THP‐1‐derived macrophages (THP‐1 macrophages). In the presence of acetylated low‐density lipoprotein, macrophages infected with an adenovirus expressing human adipophilin showed a 31% increase in triglyceride content and a greater number of lipid droplets compared with control cells. Incubation of macrophages with very low‐density lipoprotein (VLDL) dramatically increased cellular triglyceride content similarly in control and adipophilin‐overexpressing cells. By itself, VLDL increased adipophilin expression, which explains the lack of effect of adipophilin overexpression on cellular triglyceride content in macrophages loaded with VLDL. The lipid‐droplet content of macrophages was increased by overexpression of adipophilin and/or loading with VLDL. In contrast, inhibition of adipophilin expression using siRNA prevented lipid‐droplet formation and significantly reduced intracellular triglyceride content. Using inhibitors of β‐oxidation and acyl‐coenzyme A synthetase, results were obtained which suggest that adipophilin elevates cellular lipids by inhibition of β‐oxidation and stimulation of long‐chain fatty acid incorporation into triglycerides. Adipophilin expression in THP‐1 macrophages altered the cellular content of different lipids and enhanced the size of lipid droplets, consistent with a role for adipophilin in human foam cell formation.
A modelling approach to quantify dynamic crosstalk between the pheromone and the starvation pathway in baker's yeast
Authors: Schaber Jörg , Kofahl Bente , Kowald Axel , Klipp Edda
Published: July 2006

Cells must be able to process multiple information in parallel and, moreover, they must also be able to combine this information in order to trigger the appropriate response. This is achieved by wiring signalling pathways such that they can interact with each other, a phenomenon often called crosstalk. In this study, we employ mathematical modelling techniques to analyse dynamic mechanisms and measures of crosstalk. We present a dynamic mathematical model that compiles current knowledge about the wiring of the pheromone pathway and the filamentous growth pathway in yeast. We consider the main dynamic features and the interconnections between the two pathways in order to study dynamic crosstalk between these two pathways in haploid cells. We introduce two new measures of dynamic crosstalk, the intrinsic specificity and the extrinsic specificity. These two measures incorporate the combined signal of several stimuli being present simultaneously and seem to be more stable than previous measures. When both pathways are responsive and stimulated, the model predicts that (a) the filamentous growth pathway amplifies the response of the pheromone pathway, and (b) the pheromone pathway inhibits the response of filamentous growth pathway in terms of mitogen activated protein kinase activity and transcriptional activity, respectively. Among several mechanisms we identified leakage of activated Ste11 as the most influential source of crosstalk. Moreover, we propose new experiments and predict their outcomes in order to test hypotheses about the mechanisms of crosstalk between the two pathways. Studying signals that are transmitted in parallel gives us new insights about how pathways and signals interact in a dynamical way, e.g., whether they amplify, inhibit, delay or accelerate each other.
The duality of LysU, a catalyst for both Ap4A and Ap3A formation
Authors: Wright Michael , Boonyalai Nonlawat , Tanner Julian A. , Hindley Alison D. , Miller Andrew D.
Published: July 2006

Heat shock inducible lysyl‐tRNA synthetase of Escherichia coli (LysU) is known to be a highly efficient diadenosine 5′,5′′′‐P1,P4‐tetraphosphate (Ap4A) synthase. However, we use an ion‐exchange HPLC technique to demonstrate that active LysU mixtures actually have a dual catalytic activity, initially producing Ap4A from ATP, before converting that tetraphosphate to a triphosphate. LysU appears to be an effective diadenosine 5′,5′′′‐P1,P3‐triphosphate (Ap3A) synthase. Mechanistic investigations reveal that Ap3A formation requires: (a) that the second step of Ap4A formation is slightly reversible, thereby leading to a modest reappearance of adenylate intermediate; and (b) that phosphate is present to trap the intermediate (either as inorganic phosphate, as added ADP, or as ADP generated in situ from inorganic phosphate). Ap3A forms readily from Ap4A in the presence of such phosphate‐based adenylate traps (via a ‘reverse‐trap’ mechanism). LysU is also clearly demonstrated to exist in a phosphorylated state that is more physically robust as a catalyst of Ap4A formation than the nonphosphorylated state. However, phosphorylated LysU shows only marginally improved catalytic efficiency. We note that Ap3A effects have barely been studied in prokaryotic organisms. By contrast, there is a body of literature that describes Ap3A and Ap4A having substantially different functions in eukaryotic cells. Our data suggest that Ap3A and Ap4A biosynthesis could be linked together through a single prokaryotic dual ‘synthase’ enzyme. Therefore, in our view there is a need for new research into the effects and impact of Ap3A alone and the intracellular [Ap3A]/[Ap4A] ratio on prokaryotic organisms.
Expression and characterization of soluble forms of the extracellular domains of the β, γ and ε subunits of the human muscle acetylcholine receptor
Authors: Kostelidou Kalliopi , Trakas Nikolaos , Zouridakis Marios , Bitzopoulou Kalliopi , Sotiriadis Alexandros , Gavra Ira , Tzartos Socrates J.
Published: July 2006

The nicotinic acetylcholine receptor (AChR) is a ligand‐gated ion channel found in muscles and neurons. Muscle AChR, formed by five homologous subunits (α2βγδ or α2βγε), is the major antigen in the autoimmune disease, myasthenia gravis (MG), in which pathogenic autoantibodies bind to, and inactivate, the AChR. The extracellular domain (ECD) of the human muscle α subunit has been heterologously expressed and extensively studied. Our aim was to obtain satisfactory amounts of the ECDs of the non‐α subunits of human muscle AChR for use as starting material for the determination of the 3D structure of the receptor ECDs and for the characterization of the specificities of antibodies in sera from patients with MG. We expressed the N‐terminal ECDs of the β (amino acids 1–221; β1–221), γ (amino acids 1–218; γ1–218), and ε (amino acids 1–219; ε1–219) subunits of human muscle AChR in the yeast, Pichia pastoris. β1–221 was expressed at ≈ 2 mg·L−1 culture, whereas γ1–218 and ε1–219 were expressed at 0.3–0.8 mg·L−1 culture. All three recombinant polypeptides were glycosylated and soluble; β1–221 was mainly in an apparently dimeric form, whereas γ1–218 and ε1–219 formed soluble oligomers. CD studies of β1–221 suggested that it has considerable β‐sheet secondary structure with a proportion of α‐helix. Conformation‐dependent mAbs against the ECDs of the β or γ subunits specifically recognized β1–221 or γ1–218, respectively, and polyclonal rabbit antiserum raised against purified β1–221 bound to 125I‐labeled α‐bungarotoxin‐labeled human AChR. Moreover, immobilization of each ECD on Sepharose beads and incubation of the ECD–Sepharose matrices with MG sera caused a significant reduction in the concentrations of autoantibodies in the sera, showing specific binding to the recombinant ECDs. These results suggest that the expressed proteins present some near‐native conformational features and are thus suitable for our purposes.
Patatins, Kunitz protease inhibitors and other major proteins in tuber of potato cv. Kuras
Authors: Bauw Guy , Nielsen Heidi V. , Emmersen Jeppe , Nielsen Kåre L. , Jørgensen Malene , Welinder Karen G.
Published: July 2006

The major potato tuber proteins of the Kuras cultivar, which is the dominant cultivar used in Northern Europe for industrial starch production, were analysed using 1D and 2D gel electrophoresis. The electrophoretic patterns varied significantly depending on the method of preparation and the potato variant (Solanum tuberosum). Proteins were characterized using MS and scored against potato protein databases, derived from both ‘Kuras only’ and ‘all potato’ expressed sequence tags (EST) and full‐length cDNAs. Despite the existence of ∼ 180 000 ESTs, the currently available potato sequence data showed a severe under‐representation of genes or long transcripts encoding proteins > 50 kDa (3.5% of all) compared with the complete proteome of Arabidopsis thaliana (33% of all). We found that patatin and Kunitz protease inhibitor (KPI) variants are extraordinarily dominant in Kuras tuber and, most significantly, that their amino acid sequences are specific to Kuras. Other proteins identified include annexin, glyoxalase I, enolase and two lipoxygenases, the sequences of which are highly conserved among potato variants. Known S. tuberosum patatins cluster into three clades all represented in Kuras. S. tuberosum KPIs cluster into more diverse clades of which five were found in Kuras tuber, including a novel clade, KPI K, found to date only in Kuras. Furthermore, protein abundance was contrasted with the levels of corresponding gene transcripts found in our previous EST and LongSAGE studies of Kuras tuber.
Voltage‐ and Ca2+‐activated potassium channels in Ca2+ store control Ca2+ release
Authors: Yamashita Masayuki , Sugioka Miho , Ogawa Yoichi
Published: July 2006

Ca2+ release from Ca2+ stores is a ‘quantal’ process; it terminates after a rapid release of stored Ca2+. To explain the quantal nature, it has been supposed that a decrease in luminal Ca2+ acts as a ‘brake’ on store release. However, the mechanism for the attenuation of Ca2+ efflux remains unknown. We show that Ca2+ release is controlled by voltage‐ and Ca2+‐activated potassium channels in the Ca2+ store. The potassium channel was identified as the big or maxi‐K (BK)‐type, and was activated by positive shifts in luminal potential and luminal Ca2+ increases, as revealed by patch‐clamp recordings from an exposed nuclear envelope. The blockage or closure of the store BK channel due to Ca2+ efflux developed lumen‐negative potentials, as revealed with an organelle‐specific voltage‐sensitive dye [DiOC5(3); 3,3’‐dipentyloxacarbocyanine iodide], and suppressed Ca2+ release. The store BK channels are reactivated by Ca2+ uptake by Ca2+ pumps regeneratively with K+ entry to allow repetitive Ca2+ release. Indeed, the luminal potential oscillated bistably by ∼45 mV in amplitude. Our study suggests that Ca2+ efflux‐induced store BK channel closures attenuate Ca2+ release with decreases in counter‐influx of K+.
The aggregation potential of human amylin determines its cytotoxicity towards islet β‐cells
Authors: Konarkowska Barbara , Aitken Jacqueline F. , Kistler Joerg , Zhang Shaoping , Cooper Garth J. S.
Published: July 2006

Human amylin is a small fibrillogenic protein that is the major constituent of pancreatic islet amyloid, which occurs in most subjects with type 2 diabetes. There is evidence that it can elicit in vitro apoptosis in islet β‐cells, but the physical properties that underpin its cytotoxicity have not been clearly elucidated. Here we employed electron microscopy, thioflavin T fluorescence and CD spectroscopy to analyze amylin preparations whose cytotoxic potential was established by live–dead assay in cultured β‐cells. Highly toxic amylin contained few preformed fibrils and initially showed little β‐sheet content, but underwent marked time‐dependent aggregation and β‐conformer formation following dissolution. By contrast, low‐toxicity amylin contained abundant preformed fibrils, and demonstrated high initial β‐sheet content but little propensity to aggregate further once dissolved. Thus, mature amylin fibrils are not toxic to β‐cells, and aggregates of fibrils such as occur in pancreatic islet amyloid in vivo are unlikely to contribute to β‐cell loss. Rather, the toxic molecular species is likely to comprise soluble oligomers with significant β‐sheet content. Attempts to find ways of protecting β‐cells from amylin‐mediated death might profitably focus on preventing the conformational change from random coil to β‐sheet.
Functional interaction of Escherichia coli heat‐labile enterotoxin with blood group A‐active glycoconjugates from differentiated HT29 cells
Authors: Galván Estela M. , Roth German A. , Monferran Clara G.
Published: July 2006

Human colon adenocarcinoma cells (HT29‐ATCC) and the clone HT29‐5F7 were cultured under conditions that differentiate cells to a polarized intestinal phenotype. Differentiated cells showed the presence of junctional complexes and intercellular lumina bordered by microvilli. Intestinal brush border hydrolase activities (sucrase, aminopeptidase N, lactase and maltase) were detected mainly in differentiated HT29‐ATCC cells compared with the differentiated clone, HT29‐5F7. The presence of non‐GM1 receptors of Escherichia coli heat‐labile enterotoxin (LT‐I) on both types of differentiated HT29 cells was indicated by the inability of cholera toxin B subunit to block LT‐I binding to the cells. Binding of LT‐I to cells, when GM1 was blocked by the cholera toxin B subunit, was characterized by an increased number of LT‐I receptors with respect to undifferentiated control cells. Moreover, both types of differentiated cells accumulated higher amounts of cyclic AMP in response to LT‐I than undifferentiated cells. Helix pomatia lectin inhibited the binding of LT‐I to cells and the subsequent production of cyclic AMP. LT‐I recognized blood group A‐active glycosphingolipids as functional receptors in both HT29 cell lines and the active pro‐sucrase form of the glycoprotein carrying A‐blood group activity present in HT29‐ATCC cells. These results strongly suggest that LT‐I can elicit an enhanced functional response using blood group A‐active glycoconjugates as additional receptors on polarized intestinal epithelial cells.
Potential Risk of Hybridization in Ex Situ Collections of Two Endangered Species of Sinojackia Hu (Styracaceae)
Authors: Ye Qi‐Gang , Yao Xiao‐Hong , Zhang Sheng‐Ju , Kang Ming , Huang Hong‐Wen
Published: July 2006

Spontaneous hybridization in ex situ facilities can undermine the genetic integrity of ex situ collections and potentially contaminate open‐pollinated seeds or seedlings destined for the reintroduction of endangered plant species into the wild. In the present study, the potential risk of hybridization between two endangered Chinese endemic species, namely Sinojackia xylocarpa Hu and S. rehderiana Hu, which are naturally allopatric species but were conserved ex situ in Wuhan Botanical Garden (WBG), Wuhan, China, were investigated over three consecutive years from 2003 to 2005. The entire overlapping flowering period of the two species was 14–20 d and the two species shared the same pollinator insects during the entire flowering season in WBG. The floral isolation between the two species was not an issue in the ex situ collection at WBG. The results suggest an opportunity for pollen transfer between species and a potential risk of genetic introgression and loss of genetic identity of open‐pollinated seeds produced in the ex situ collection of these two endangered species. An artificial reciprocal cross between S. xylocarpa and S. rehderiana confirmed that the two congener species could readily set seeds, indicating no post‐pollination barriers to hybridization and the importance of spatial isolation as a barrier to inter‐specific crossing. Therefore, to manage these crossable species with overlapping flowering times and shared pollination vectors in ex situ facilities, spatial isolation should be carefully considered to minimize the possibility of spontaneous hybridization.

(Managing editor: Wei Wang)
Diversity of Nitrogenase Systems in Diazotrophs
Authors: Zhao Ying , Bian Shao‐Min , Zhou Hui‐Na , Huang Ju‐Fu
Published: July 2006

Nitrogenase is a metalloprotein complex that catalyses the reaction of biological nitrogen fixation. At least three genetically distinct nitrogenase systems have been confirmed in diazotrophs, namely Nif, Vnf, and Anf, in which the active‐site central metals are Mo, V, and Fe, respectively. The present review summarizes progress on the genetic, structural, and functional investigations into the three nitrogenases and discusses the possibility of the existence of other novel nitrogenases.

(Managing editor: Ping He)
Introgression of Resistance to Powdery Mildew Conferred by Chromosome 2R by Crossing Wheat Nullisomic 2D with Rye
Authors: An Diao‐Guo , Li Li‐Hui , Li Jun‐Ming , Li Hong‐Jie , Zhu Yong‐Guan
Published: July 2006

Using the nullisomic back‐cross procedure, four wheat‐rye chromosome substitution 2R (2D) lines with different agronomic performance, designated WR02‐145‐1, WR01‐145‐2, WR02‐145‐3, and WR02‐145‐4, were produced from a cross between 2D nullisomic wheat (Triticum aestivum L. cv. “Xiaoyan 6”) and rye (Secale cereale L. cv. “German White”). The chromosomal constitution of 2n=42=21 in WR02‐145 lines was confirmed by cytological and molecular cytogenetic methods. Using genomic in situ hybridization on root tip chromosome preparations, a pair of intact rye chromosomes was detected in the WR02‐145 lines. PCR using chromosome‐specific primers confirmed the presence of 2R chromosomes of rye in these wheat‐rye lines, indicating that WR02‐145 lines are disomic chromosome substitution lines 2R(2D). The WR02‐145 lines are resistant to the powdery mildew (Erysiphe graminis DC. f. sp. tritici E. Marchal) isolates prevalent in northern China and may possess gene(s) for resistance to powdery mildew, which differ from the previously identified Pm7 gene located on chromosome 2RL. The newly developed “Xiaoyan 6”‐ “German White” 2R (2D) chromosome substitution lines are genetically stable, show desirable agronomic traits, and are expected to be useful in wheat improvement.

(Managing editor: Li‐Hui Zhao)
Effects of Exogenous Indole Butyric Acid and Callus Formation on the Anti‐oxidant Activity, Total Phenolic, and Anthocyanin Constituents of Mulberry Cuttings
Authors: Sivaci Aysel , Sokmen Munevver
Published: July 2006

In order to evaluate the effects of exogenous indole butyric acid (IBA) and callus formation on the anti‐oxidant activity, total phenolics, and anthocyanin constituents of Morus nigra L. and M. alba L. cuttings, we investigated the variations before and after the treatment. The results indicate that anti‐oxidant ability, total phenolic, and anthocyanin constituents of the callus stems of both Morus species were higher than those of non‐callus forming species. There were also increases observed in anti‐oxidant ability, total phenolic, and anthocyanin constituents of calli treated with IBA (1 000–3 000 mg/L).

(Managing editor: Wei Wang)
Isolation and Expression Analysis of Two Cold‐Inducible Genes Encoding Putative CBF Transcription Factors from Chinese Cabbage (Brassica pekinensis Rupr.)
Authors: Zhang Yong , Yang Tong‐Wen , Zhang Li‐Jing , Zhang Teng‐Guo , Di Cui‐Xia , Xu Shi‐Jian , An Li‐Zhe
Published: July 2006

Two homologous genes of the Arabidopsis C‐repeat/dehydration‐responsive element binding factors (CBF/DREB1) transcriptional activator were isolated by RT‐PCR from Chinese cabbage (Brassica pekinensis Rupr. cv. Qinbai 5) and were designated as BcCBF1 and BcCBF2. Each encodes a putative CBF/DREB1 protein with an AP2 (Apetal2) DNA‐binding domain, a putative nuclear localization signal, and a possible acidic activation domain. Deduced amino acid sequences show that BcCBF1 is very similar to the Arabidopsis CBF1, whereas BcCBF2 is different in that it contains two extra regions of 24 and 20 amino acids in the acidic domain. The mRNA accumulation profiles indicated that the expression of BcCBF1 and BcCBF2 is strongly induced by cold treatment, but does not respond similarly to dehydration or abscisic acid (ABA) treatment. However, the cold‐induced accumulation of BcCBF2 mRNA was rapid but short‐lived compared with that of BcCBF1. The mRNA levels of both BcCBF1 and BcCBF2 were higher in leaves than in roots when plants were exposed to cold, whereas, salt stress caused higher accumulation of BcCBF2 mRNA in roots than in leaves, suggesting that the organ specificity of the gene expression of the BcCBFs is probably stress dependent. In addition, the accumulation of BcCBF1 and BcCBF2 mRNAs was greatly enhanced by light compared with darkness when seedlings were exposed to cold. It is concluded that the two BcCBF proteins may be involved in the process of plant response to cold stress through an ABA‐independent pathway and that there is also a cross‐talk between the light signaling conduction pathway and the cold response pathway in B. pekinensis as in Arabidopsis.

(Managing editor: Li‐Hui Zhao)
Physiological Responses of Zea mays Seedlings to Interactions Between Cadmium and Salinity
Authors: Sepehr Mozhgan Farzami , Ghorbanli Mahlagha
Published: July 2006

The effects of 0, 2.5, 5.0, and 10.0 μmol/L Cd2+ (Cd(NO3)2‐4H2O) and 0,10, 25, 50, and 100 mmol/L NaCl on growth, photosynthesis and the content of some ions in maize (Zea mays L.) were investigated in the present study. With increasing concentrations of Cd2+ or NaCl alone in Hoagland nutrient solution, the chlorophylls and starch content decreased. Combination treatment with salinity and cadmium increased the negative effects observed following the two stresses alone. Plants exhibiting growth retardation in response to one mild stress factor (25–50 mmol/L NaCl) became more tolerant to the other stress factor (Cd). The exposure of plants to cadmium caused a partial reversal of the effects of salinity. Root and shoot growth, ion accumulation and levels of photosynthetic pigments were improved at moderate concentrations of the two stress factors imposed jointly.

(Managing editor: Ping He)