Elizabeth Vardaka

The effect of Cu, Zn and Pb on the chlorophyll content of the lichens Cladonia convoluta and Cladonia rangiformis

Abstract It was hypothesised that Cu was responsible for the reduced chlorophyll content of lichens growing in mining areas in which Cu, Zn, and Pb were present in the soil. Therefore, the effect of Cu, Zn, and Pb, individually and in combination, on the respective thallus metal content of the lichens Cladonia convoluta and Cladonia rangiformis , and the subsequent effect on chlorophyll content, were examined. Increasing lichen Cu content (up to 1600 μg g −1 dry weight (DW)) had no effect on the total chlorophyll content of C. rangiformis , whereas in C. convoluta Cu concentrations exceeding 175 μg g − 1 DW caused a decrease in total chlorophyll content, which was 40% at 1560 μg Cu g −1 DW. Lichen Zn and Pb concentrations of up to 1050 and 3350 μg g −1 DW for C. convoluta and 1210 and 8500 μg g −1 DW for C. rangiformis , respectively, had no effect on the total chlorophyll content of either lichen. The chlorophyll a/b ratio was more sensitive to changes in lichen metal content. A marked decrease in the ratio of chlorophyll a/b, from 3.0 to 0.4 for C. convoluta and from 3.2 to 0.8 for C. rangiformis , occurred when the thallus Cu content exceeded 175 and 200 μg g −1 DW, respectively. Zn and Pb caused a 10–15% decrease of the ratio of chlorophyll a/b for C. convoluta at concentrations exceeding 140 and 20 μg g −1 DW, respectively. The chlorophyll a/b ratio of C. rangiformis was unaffected by increasing thallus Zn content, whereas an increase in thallus Pb content caused a slight increase in the chlorophyll a/b ratio. The decrease in the ratio of chlorophyll a/b with increasing lichen Cu content was caused by a decrease in chlorophyll a and an increase in chlorophyll b concentration in both lichens. The Cu effects on chlorophyll were reduced in the presence of Pb and Zn in both lichens, but to a lesser extent in C. rangiformis . Metal cations appeared to be ionically bound within the cell wall in an exchangeable form with binding affinities of Pb>Cu>Zn. It would appear that of these cations only Cu is taken up into the photobiont cells. Cu may interfere with the biosynthesis of chlorophyll or cause lipid peroxidation processes in the photosynthetic membranes.

Limnothrix redekei (Van Goor) Meffert (Cyanobacteria) Strains from Lake Kastoria, Greece Form a Separate Phylogenetic Group

Three strains of Limnothrix (Cyanobacteria) isolated from Lake Kastoria, Greece, were characterized based on their morphological features and 16S rRNA gene sequences. The Limnothrix isolates 007a, 165a, and 165c can morphologically be assigned to Limnothrix redekei (Van Goor) Meffert. The 16S rRNA gene of the Limnothrix strains showed a 99% similarity to the 16S rRNA gene of Planktothrix sp. FP1. Limnothrix redekei strains 165a, 165c, 007a and Planktothrix sp. FP1 formed a separate cluster in the cyanobacterial 16S rRNA gene tree. It was distinct from the Pseudanabaena cluster, which included the other Limnothrix strains isolated from northern temperate lakes. This is the first report on the phylogeny of L. redekei strains originating from a Mediterranean lake (southern Europe) and provides new data about the genus Limnothrix.

Cyanobacterial blooms and water quality in Greek waterbodies

The cyanobacterial species composition of nine Greek waterbodies of different type and trophic status was examined during the warm period of the year (May–October). Cyanobacterial water blooms were observed in all waterbodies. Forty-six cyanobacterial taxa were identified, 11 of which are known to be toxic. Eighteen species are reported for the first time in these waterbodies, 8 of which are known to produce toxins. Toxin producing species were found in all of the waterbodies and were primarily dominant in bloom formations (e.g., Microcystis aeruginosa, Anabaena flos-aquae, Aphanizomenon flos-aquae and Cylindrospermopsis raciborskii). Cosmopolitan species (e.g., M. aeruginosa), pantropic (e.g., Anabaenopsis tanganyikae) and holarctic species (e.g., Anabaena flos-aquae) were encountered. Shallow, eutrophic waterbodies had blooms dominated by Microcystis species and were characterized by phytoplankton association M. Anabaena and Aphanizomenon species of association H were dominant in waterbodies with low dissolved inorganic nitrogen and thermal stratification in the summer. Total cyanobacterial biovolumes (CBV) ranged from 7 to 9,507 cm3 m−3 and were higher than Alert Level 2 and Guidance Level 2 (10 cm3 m−3; World Health Organization; WHO) in seven of the waterbodies. Chlorophyll a concentrations ranged from 6 to 90,000 mg m−3 and were higher than Alert Level 2 and Guidance Level 2 (50 mg m−3; WHO) in eight of the waterbodies. There is also an elevated risk of acute toxicosis (Guidance Level 3; WHO) in five waterbodies. Water of an undesirable quality, hazardous to humans and animals occurs in several Greek waterbodies.

Effects of copper on the growth, photosynthesis and nutrient concentrations of Phaseolus plants

Bean plants (Phaseolus vulgaris L. var. Zargana Kavala) were grown under conditions of increasing Cu concentrations in the growth medium (0.5-160.5 µM). Generally, the Cu concentrations between 0.5-1.5 µM were deficient, 1.5-10.5 µM were optimal, and 10.5-160.5 µM were toxic to plant growth. The Cu toxicity was associated with marked increases in plant tissue Cu concentrations. Under the Cu-deficient and optimal growth conditions, Cu was located primarily in the leaves. Under Cu toxicity, it was primarily sequestered in the roots. With increasing Cu in the growth medium, there was a positive correlation between Cu concentrations in the roots, stems and leaves, Ca in the roots, and K and Mg in the leaves. In contrast, Ca concentrations in the leaves and stems showed a negative correlation. The chlorophyll (Chl) concentration increased with increasing leaf Cu concentration, however, the Chl a/b ratio decreased. Since with an increasing leaf Cu concentration the leaf area decreased more markedly than the leaf dry mass, the net photosynthetic rate (PN) per leaf area increased and per dry mass decreased. The increase in PN per leaf area was almost entirely accounted for by the increase in Chl concentration. The initial Chl fluorescence (F0) increased with increasing leaf Cu concentration. The ratio of variable to maximum fluorescence (Fv/Fm) under Cu toxicity decreased. The half-time for the rise from F0 to Fm (t1/2) remained relatively unchanged with increasing leaf Cu concentration. Therefore the Cu-stress caused a small decrease in the efficiency of photosystem 2 photochemistry, but its primary effect was on growth.

Helicobacter pylori Infection Might Contribute to Esophageal Adenocarcinoma Progress in Subpopulations With Gastroesophageal Reflux Disease and Barrett's Esophagus

To the Editor, Fischbach et al. [1] concluded that estimates for the effect of Helicobacter pylori (H. pylori) on Barrett’s esophagus (BE) were heterogenous across studies; although overall H. pylori, and particularly cagA cytotoxin, tended to be protective for BE in most studies, H. pylori effect on BE varied by geographic location. Barrett’s esophagus is a complication of long-standing gastroesophageal reflux disease (GERD) and wellrecognized premalignant condition playing a pivotal role in the development of esophageal adenocarcinoma (EA), the most common esophageal malignancy in Western countries with increasing faster incidence than any other cancer [2]; GERD plays a crucial role in the pathophysiology and the clinical identification of BE [2]. In this regard, our data show that H. pylori infection (H. pylori-I) is frequent in Greek patients with GERD and even with nonendoscopical reflux disease [2], and H. pylori eradication leads to better control of GERD symptoms and improves esophagitis [2,3]. Moreover, consistent associations with the Greek data were shown by others [3] also reporting improvement in reflux symptoms following H. pylori treatment. It is important to note that some other authors, usually prior supporters of the theory that H. pylori “protects” against GERD, relented their initial findings, claiming that H. pylori eradication does not cause or protect against GERD and, moreover, recommending H. pylori eradication in GERD [4]. Additionally, although epidemiologic studies do not suggest causality with H. pylori, however, such studies support our and others’ findings; for instance, a large study (~21,000 cases) showed that the decrease in H. pylori-I parallels the decrease in peptic ulcer prevalence, and the increase in GERD and reappearance of GERD after H. pylori eradication is rare. Moreover, contrary to expectation, patients hospitalized with duodenal ulcers (61,548 cases), obviously attributed to H. pylori-I, had a significant 70% excess risk of EA. Much evidence further potentiates the concern that H. pylori is not “protective” against GERD [5] and its complications including BE and EA. The interplay between H. pylori and host factors plays an important role in the pathogenesis of GERD. Specifically, H. pylori may contribute to GERD pathogenesis by several mechanisms including release of several mediators, cytokines, and nitric oxide, which may adversely affect the lower esophageal sphincter (LES); direct damage of the esophageal mucosa by bacterial products; increased production of prostaglandins that sensitize afferent nerves and reduce LES pressure; and augmented acidity (by gastrin release) that exacerbate GERD [3]. The authors considered some putative pathways involving H. pylori and a decreased risk of BE [1]. However, these pathways might represent the one BE pathogenic “coin’s” side. Regarding the other alternative side, gastrin, induced by H. pylori-I, is an oncogenic growth factor contributing to esophageal, gastric, and colon carcinogenesis and, in particular, playing a potential causal effect on neoplastic progression in BE; gastrin stimulates proliferation via JAK2and Akt-dependent NF-kappaB (NF-jB) activation in Barrett’s EA cells, shows antiapoptotic activity through upregulation of Bcl-2 and survivin, and upregulates cyclooxygenase (COX)-2 expression [2]. In this regard, H. pylori-I activates NF-jB, an oxidantsensitive transcription regulator of inducible expression of inflammatory genes such as COX-2, which regulates gastrointestinal cancer cell growth and proliferation. In particular, H. pylori-I induced NF-jB and COX-2 expression in esophageal epithelial cells, playing a role in inflammation associated with BE and tumorigenesis in the esophagus [2]; upon colonizing esophagus, H. pylori increases the severity of esophageal inflammation and the incidence of BE and EA [6]. Moreover, recent evidence indicates that 1, H. pylori-I prevalence is high in BE; 2, neither H. pylori-I nor H. pylori-I by CagA+ strains reduce the risk of BE in certain populations with high prevalence of H. pylori-I; 3, the expected incidence of EA with persistent H. pylori-I is higher than that of EA after eradication of infection [5]; H. pylori-I may affect specific molecular alterations (genetic instability, E-cadherin methylation, and monoclonal antibody Das-1) associated with the pathogenesis of BE; and 4, H. pylori induces

Helicobacter pylori infection and colorectal carcinoma: pathologic aspects

To the Editor, Fleming et al. (1), by reviewing the pathologic aspects of colorectal neoplasms, summarized the pathogenesis and molecular classification of colorectal carcinoma (CRC) including mainly molecular pathways and environmental factors. However, they did not mention the potential pathologic aspects of environmental factors involved in colorectal oncogenesis, particularly in sporadic CRC. More than 95% of colorectal cancers are sporadic, also mentioned by the authors (1), without a significant hereditary risk. Geographic variation in the incidence of CRC is substantial with a higher incidence observed in the West. Environmental factors contribute considerably to this variation (2); the majority of the sporadic cancer is believed to be due to modification of mutation risk by other genetic and/or environmental factors. Dietary factors may influence the oncogenic process by modifying intestinal transit time, altering the flow and recycling of bile, or changing the intestinal bacterial flora composition. Numerous studies support a role for the gut microbiota in colorectal oncogenesis and the colonic microbiota drives the progression towards colorectal malignancy including generation of reactive metabolites and carcinogens, alterations in host carbohydrate expression and induction of chronic mucosal inflammation (3); long-term colonization of the colon by rogue commensal bacteria capable of inducing chronic DNA damage could contribute to sporadic CRC developement, thereby suggesting sporadic CRC as an infectious disease (4). In this regard, Helicobacter pylori (Hp), a curved spiral gram-negative bacterium found in the gastric mucosa of a large proportion of humans worldwide (>50%), has been evaluated as a possible etiologic agent for CRC and recent data indicate that there is a serological association between Hp infection (Hp-I) and the risk of CRC, especially for left-sided and early-stage cancers (5). Moreover, Hp seropositive subjects are associated with a modest increase in the risk for colorectal adenoma, and since Hp-I can increase the risk especially of advanced adenomas, the medical community should take into account that a preventive strategy is needed, and, furthermore, elucidating the pathophysiological role of Hp in the development of CRC is highly warranted (6). However, as mentioned by the authors (5,6), the serologic measurement of infection status is less than perfect, thereby representing a specific limitation of their studies. Indeed, the serological test does not discriminate between current and past infections and, apart from past infection that may even be more relevant for oncogenesis, such a distinction is essential because only current Hp-I induces humoral and cellular immune responses that produce or perpetuate chronic inflammatory processes in gastrointestinal tract with potential oncogenic sequelae; many neoplasms including colorectal adenomas and cancers arise at the sites of chronic inflammation and infection (7-10). Based on histology, the practical gold standard for Hp-I diagnosis, our own preliminary studies indicated Hp presence in malignant tissue in 34 of 41 (82.9%) patients with CRC (23 men, mean age 73.6±7.9 years) (11). Extending these preliminary data we currently included 50 patients (28 men, mean age 71.3±9.7 years) with CRC and 25 patients (13 men, mean age 72.8±10.1 years) with colonic polyps with the following results: Hp presence in malignant and polyp tissues of patients were observed in 84% and 64%, respectively, confirming our preliminary data (12). It is important to note that, apart from Cresyl fast violet staining mainly used to detect Hp, its presence was also documented by immunohistochemical method (using polyclonal rabbit anti-Hp antibody (dilution 1:50, DAKO, Athens, Greece) in adenoma and malignant colonic tissues. Specifically, in accordance with Hong et al. (6), Hp progressive increased presence was observed in our patients with adenomas associated with mild (50%) and moderate/high-grade (80%) dysplasia; the latter lesions are frequently described as advanced adenomas. However, contrary to the authors’ considerations (6), our series showed an increased Hp presence in left-sided (79%) than in the proximal colon (21%) adenomas; left-sided cancers were also observed in 70.7% of our patients, a finding also noticed by Zhang et al. (5), thereby suggesting that Hp-I might be associated with a rather relevant risk increase in the left CRC. The multistep model of gastric cancer postulates that there is initially an inflammation, caused mainly by Hp-I, which can lead to the development of chronic active gastritis. In a subset of these patients, this inflammatory process leads to the development of atrophic gastritis, followed by intestinal metaplasia, dysplasia, and, ultimately, early and advanced gastric cancer (13). It is considered that all stages prior to the development of high-grade dysplasia are potentially reversible, although this is still controversial (13). Because, Hp also induces inflammatory changes in colonic mucosa (14), it would be reasonable to further speculate, in view of our data, that chronic inflammatory process induced by Hp-I in colonic mucosa may lead to adenoma - mild-moderate/high grade dysplasia - CRC development sequence. These findings may emphasize the need for Hp eradication to prevent the development of both colon and gastric cancer (13). In addition, we found that presence of Hp in malignant colonic tissue was associated with Ki-67 oncogene increased expression in all tumor specimens and low expression in all adjacent tissue specimens (15). Moreover, p53 increased and low expression was observed in 72.5% and 100% of tumor and adjacent tissues specimens, respectively. Likewise, antiapoptotic Bcl-2 protein was observed in 60% and 9% of tissue specimens, respectively, whereas proapoptotic Bax protein was observed in 9% and 100% of tissue specimens, respectively (15). Therefore, Hp colonizing colonic neoplasm tissue seems to be associated with an increased cell proliferation and impaired apoptotic process in malignant tissue compared with normal adjacent colonic mucosa, thereby possibly contributing to colon normal mucosa-adenoma-cancer sequence (15). In this regard, Hp-induced gastrin as an oncogenic growth factor, shows antiapoptotic activity through the Bcl-2 upregulation and contributes to gastric and colon carcinogenesis through stimulation of mutagenic and tumorigenic cyclooxygenase-2 expression (16). Animal models suggested the mitogenic action of gastrin to be limited to the left colon, elevated gastrin levels are more pronounced in their associations with rectal than with colon cancer, and the relation between hypergastrinemia and colorectal adenomas confers an increased risk only for distal colon adenomas. These findings are consistent with and may explain our findings and Zhang et al. (5) findings of selective risk increase with respect to left-sided CRC and adenomas. Experimental data indicate that Hp-I leads to development of chronic inflammation, hyperplasia, metaplasia, dysplasia and recruitment and accumulation of bone marrow-derived cells (BMDCs) which may contribute to tumor formation in animal models with Hp-induced chronic gastric inflammatory process (9,13). Because Hp similarly induces the mentioned inflammatory changes in colonic mucosa (14), it would be reasonable to further speculate that chronic Hp-I in humans also induces repopulation of the colon with BMDCs that might facilitate colon adenoma and cancer development and progression (9,13). In this regard, our own preliminary studies indicated increased expression of CD44 [a marker of human hematopoietic stem and progenitor cells and cancer stem cells (CSCs)] in malignant colonic tissue in 75.6% patients with CRC (11). Extending these preliminary data, increased expression of CD44 was observed in 78% and 16% of patients with cancers and polyps, respectively (12). We also obtained comparable data with gastric cancer (9,13). Therefore, these findings suggest the possible BMDCs and/or CSCs involvement in Hp-associated gastric cancer development and colon adenoma and cancer growth and/or progression (9,13). However, larger-scale future studies are warranted to show that the BMDCs move into areas of the upper and lower gastrointestinal tract and/or CSCs might be induced in the context of Hp chronic injury or inflammation with potential long-term colon adenoma malignant consequences in Hp-positive subjects. Finally, it is important to know if the authors (1) considered relative pathologic aspects in their studies.

Helicobacter pylori infection and Parkinson's disease: apoptosis as an underlying common contributor.

Nielsen et al. [1] state that Helicobacter pylori infection (Hp-I) may play an important role in the pathogenesis of Parkinson s disease (PD) by triggering microglia activation through the humeral or vagal afferent pathways. In this regard, apoptotic rather than necrotic microglia-associated nerve cell death appears to underlie a number of common neurological conditions including PD, Alzheimer s disease (AD), glaucoma or multiple sclerosis [2]. The latter diseases are also associated with Hp-I [2–4]; likewise, an association of glaucoma with neurodegenerative diseases (PD and AD) via apoptotic cell death has been reported. Hp, apart from Fas–FasL apoptotic pathway [2], is capable of inducing apoptotic effects through the mitochondrial apoptotic pathway involving the activation of the pro-apoptotic proteins Bax and Bak, activation of certain caspases, or through inducible nitric oxide (NO);NO is a rapidly diffusing gas and a potent neurotoxin that may contribute to apoptotic neuronal cell death in degenerative neuropathies [4], including PD. In particular, increased endothelin-1 (a potent constrictor of arterioles and venules), NO and inducible nitric oxide synthase (iNOS) levels are associated with Hp-I [2]. Relative data in AD indicate that endothelin-1-like immunoreactivity in the AD brains is significantly more increased in frontal and occipital cortex than that in the control brains, thereby explaining the decreased cerebral blood flow in patients with AD. Besides, the synthesis of NO, the peroxynitrite reactive production and the protein tyrosine nitration are activated over the entire chronic course of AD, and the presence of Abeta increases the presence of neuronal NOS and iNOS isoforms over the chronic course of AD in pyramidal-like neurons [2]; NO contributes to mitochondrial fragmentation via S-nitrosylation of dynamin-related protein 1, a protein involved in mitochondrial fission. These findings might provide a new target for drug development in AD.Moreover, redox reactions triggered by excessive levels of NO can contribute to protein misfolding, the hallmark of a number of neurodegenerative disorders, including PD andAD [5]. Finally, apart from humeral and vagal afferent pathways, mentioned by the authors [1], Hp might access brain via oral-nasal-olfactory pathway or by circulating monocytes (possibly infected with Hp owing to defective autophagy) through disrupted blood–brain barrier, leading to neurodegeneration [3].

Impact of reactive oxygen species generation on Helicobacter pylori-related extragastric diseases: a hypothesis.

Abstract Helicobacter pylori (H. pylori) induces reactive oxygen species (ROS) production that contribute to pathogenesis of a variety of H. pylori-related gastric diseases, as shown in animal and human studies. Helicobacter pylori infection is also associated with variety of systemic extragastric diseases in which H. pylori-related ROS production might also be involved in the pathogenesis of these systemic conditions. We proposed that Hp-related ROS may play a crucial role in the pathophysiology of Hp-related systemic diseases including Alzheimer’s disease, multiple sclerosis, glaucoma and other relative neurodegenerative diseases, thereby suggesting introduction of relative ROS scavengers as therapeutic strategies against these diseases which are among the leading causes of disability and are associated with a large public health global burden. Moreover, we postulated that H. pylori-related ROS might also be involved in the pathogenesis of extragastric common malignancies, thereby suggesting that H. pylori eradication might inhibit the development or delay the progression of aforementioned diseases. However, large-scale future studies are warranted to elucidate the proposed pathophysiological mechanisms, including H. pylori-related ROS, involved in H. pylori-associated systemic and malignant conditions.

Helicobacter pylori might contribute to nonalcoholic fatty liver disease–related cardiovascular events by releasing prothrombotic and proinflammatory factors

ur Tropenmedizin, Infektionskrankheiten und Sektion Nephrologie, Universit€atsmedizin Rostock, Rostock, Germany; Gastroenterologische Schwerpunktpraxis, Cottbus, Germany; Hepatologische Schwerpunktpraxis, Magdeburg, Germany; Klinik f€ ur Gastroenterologie und Infektiologie, E.-v.-Bergmann Klinikum, Potsdam, Germany, III. Medizinische Klinik, Krankenhaus DresdenFriedrichstadt, Dresden, Germany; Klinik f€ur Gastroenterologie und Hepatologie, Klinikum St. Georg GmbH, Leipzig, Germany, Klinik und Poliklinik f€ ur Innere Medizin I, Martin-Luther-Universit€at Halle-Wittenberg, Halle, Germany for the East German HCV Study Group.

Helicobacter pylori induced cognitive dysfunction might be associated with falls and fractures in cirrhosis

1. Lampertico P, Vigano M, Cheroni C, Facchetti F, Invernizzi F, Valveri V, et al. IL28B polymorphisms predict interferon-related HBsAg seroclearance in genotype D HBeAg-negative patients with chronic hepatitis B. HEPATOLOGY 2013;57:890-896. 2. Sonneveld MJ, Wong VW, Woltman AM, Wong GL, Cakaloglu Y, Zeuzem S, et al. Polymorphisms near IL28B and serological response to peginterferon in HBeAg-positive patients with chronic hepatitis B. Gastroenterology 2012;142:513-520. 3. Fischer J, Bohm S, Scholz M, Muller T, Witt H, George J, et al. Combined effects of different interleukin-28B gene variants on the outcome of dual combination therapy in chronic hepatitis C virus type 1 Infection. HEPATOLOGY 2012 [Epub ahead of print].