Seasonal water quality of shallow and eutrophic Lake Pamvotis, Greece: implications for restoration

Lake Pamvotis is a moderately sized (22 km²) shallow (z _avg=4 m) lake with a polymictic stratification regime located in northwest Greece. The lake has undergone cultural eutrophication over the past 40 years and is currently eutrophic (annual averages of FRP=0.07 mg P l^-1, TP=0.11 mg P l^-1, NH₄ ⁺=0.25 mg N l^-1, NO₃ ^–=0.56 mg N l^-1). FRP and NH₄ ⁺ levels are correlated to external loading from streams during the winter and spring, and to internal loading during multi-day periods of summer stratification. Algal blooms occurred in summer (July–August green algae, August–September blue-green algae), autumn (October blue-green algae and diatoms), and winter (February diatoms), but not in the spring (March–June). The phytoplankton underwent brief periods of N- and P-limitation, though persistent low transparency (secchi depth of 60–80 cm) also suggests periods of light limitation. Rotifers counts were highest from mid-summer to early autumn whereas copepods were high in the spring and cladocerans were low in the summer. Removal of industrial and sewage point sources a decade ago resulted in a decrease in FRP. A phosphorus mass balance identified further reductions in external loading from the predominately agricultural catchment will decrease FRP levels further. The commercial fishery and lake hatchery also provides opportunities to control algal biomass through biomanipulation measures.     

The Relevance of a Novel Quantitative Assay to Detect up to 40 Major Streptococcus pneumoniae Serotypes Directly in Clinical Nasopharyngeal and Blood Specimens

For epidemiological and surveillance purposes, it is relevant to monitor the distribution and dynamics of Streptococcus pneumoniae serotypes. Conventional serotyping methods do not provide rapid or quantitative information on serotype loads. Quantitative serotyping may enable prediction of the invasiveness of a specific serotype compared to other serotypes carried. Here, we describe a novel, rapid multiplex real-time PCR assay for identification and quantification of the 40 most prevalent pneumococcal serotypes and the assay impacts in pneumonia specimens from emerging and developing countries. Eleven multiplex PCR to detect 40 serotypes or serogroups were optimized. Quantification was enabled by reference to standard dilutions of known bacterial load. Performance of the assay was evaluated to specifically type and quantify S. pneumoniae in nasopharyngeal and blood samples from adult and pediatric patients hospitalized with pneumonia (n = 664) from five different countries. Serogroup 6 was widely represented in nasopharyngeal specimens from all five cohorts. The most frequent serotypes in the French, South African, and Brazilian cohorts were 1 and 7A/F, 3 and 19F, and 14, respectively. When both samples were available, the serotype in blood was always present as carriage with other serotypes in the nasopharynx. Moreover, the ability of a serotype to invade the bloodstream may be linked to its nasopharyngeal load. The mean nasopharyngeal concentration of the serotypes that moved to the blood was 3 log-fold higher than the ones only found in the nasopharynx. This novel, rapid, quantitative assay may potentially predict some of the S. pneumoniae serotypes invasiveness and assessment of pneumococcal serotype distribution.     

Histology Verification Demonstrates That Biospectroscopy Analysis of Cervical Cytology Identifies Underlying Disease More Accurately than Conventional Screening: Removing the Confounder of Discordance

Background

Subjective visual assessment of cervical cytology is flawed, and this can manifest itself by inter- and intra-observer variability resulting ultimately in the degree of discordance in the grading categorisation of samples in screening vs. representative histology. Biospectroscopy methods have been suggested as sensor-based tools that can deliver objective assessments of cytology. However, studies to date have been apparently flawed by a corresponding lack of diagnostic efficiency when samples have previously been classed using cytology screening. This raises the question as to whether categorisation of cervical cytology based on imperfect conventional screening reduces the diagnostic accuracy of biospectroscopy approaches; are these latter methods more accurate and diagnose underlying disease? The purpose of this study was to compare the objective accuracy of infrared (IR) spectroscopy of cervical cytology samples using conventional cytology vs. histology-based categorisation.

Methods

Within a typical clinical setting, a total of n = 322 liquid-based cytology samples were collected immediately before biopsy. Of these, it was possible to acquire subsequent histology for n = 154. Cytology samples were categorised according to conventional screening methods and subsequently interrogated employing attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy. IR spectra were pre-processed and analysed using linear discriminant analysis. Dunn’s test was applied to identify the differences in spectra. Within the diagnostic categories, histology allowed us to determine the comparative efficiency of conventional screening vs. biospectroscopy to correctly identify either true atypia or underlying disease.

Results

Conventional cytology-based screening results in poor sensitivity and specificity. IR spectra derived from cervical cytology do not appear to discriminate in a diagnostic fashion when categories were based on conventional screening. Scores plots of IR spectra exhibit marked crossover of spectral points between different cytological categories. Although, significant differences between spectral bands in different categories are noted, crossover samples point to the potential for poor specificity and hampers the development of biospectroscopy as a diagnostic tool. However, when histology-based categories are used to conduct analyses, the scores plot of IR spectra exhibit markedly better segregation.

Conclusions

Histology demonstrates that ATR-FTIR spectroscopy of liquid-based cytology identifies the presence of underlying atypia or disease missed in conventional cytology screening. This study points to an urgent need for a future biospectroscopy study where categories are based on such histology. It will allow for the validation of this approach as a screening tool.     

Regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase by wounding and methyl jasmonate

HMGR (3-hydroxy-3-methylglutaryl-coenzyme A reductase; E.C.1.1.1.34) supplies mevalonate for the synthesis of many plant primary and secondary metabolites, including the terpenoid component of indole alkaloids. Suspension cultures of Camptotheca acuminata and Catharanthus roseus, two species valued for their anticancer indole alkaloids, were treated with the elicitation signal transducer methyl jasmonate (MeJA). RNA gel blot analysis from MeJA treated cultures showed a transient suppression of HMGR mRNA, followed by an induction in HMGR message. Leaf disks from transgenic tobacco plants containing a chimeric hmgl::GUS construct were also treated with MeJA and showed a dose dependent suppression of wound-inducible GUS activity. The suppression of the wound response by MeJA was limited to the first 4 h post-wounding, after which time MeJA application had no effect. The results are discussed in relation to the differential regulation of HMGR isogenes in higher plants.Abbreviations GUS -glucuronidase - hmg gene of hmgr - HMGR 3-hydroxy-3-methylglutaryl-coenzyme A reductase - JA jasmonic acid - MeJA methyl jasmonate - MUG methylumbelliferyl--d-glucuronide - TDC tryptophan decarboxylase - SDS sodium dodecyl sulfate - SS strictosidine synthase     

Hematopoiesis at the onset of metamorphosis: terminal differentiation and dissociation of the <Emphasis Type="Italic">Drosophila</Emphasis> lymph gland

The Drosophila melanogaster hematopoietic organ, called lymph gland, proliferates and differentiates throughout the larval period. The lymph gland of the late larva is comprised of a large primary lobe and several smaller secondary lobes. Differentiation into two types of hemocytes, plasmatocytes and crystal cells, is confined to the outer layer (cortical zone) of the primary lobe; the center of the primary lobe (medullary zone), as well as the secondary lobes, contain only proliferating prohemocytes. A small cluster of cells located at the posterior tip of the primary lobe serves as a signaling center (PSC) that inhibits precocious differentiation of the medullary zone. The larval lymph gland is stabilized by layers of extracellular matrix (basement membranes) that surround individual hemocytes, groups of hemocytes, as well as the lymph gland as a whole. In this paper, we investigated the events shaping the lymph gland in the early pupa. The lymph gland dissociates and hemocytes disperse during the first 12 h after puparium formation (APF), leaving behind empty husks of basement membrane. Prior to lymph gland dissociation, cells of the medullary zone differentiate, expressing the early differentiation marker Peroxidasin (Pxn), as well as, in part, the late differentiation marker P1. Cells of the PSC spread throughout the pupal lymph gland prior to their dispersal. Cells of the secondary lobes undergo a rapid phase of proliferation that lasts until 8 h APF, followed by expression of Pxn and dispersal. These hemocytes do not express P1, indicating that they disperse prior to full maturation.     

Repeated Restraint Stress Alters Hippocampal Glutamate Uptake and Release in the Rat

Glutamatergic mechanisms are thought to be involved in stress-induced changes of brain function, especially in the hippocampus. We hypothesized that alterations caused by the hormonal changes associated with chronic and acute stress may affect glutamate uptake and release from hippocampal synaptosomes in Wistar rats. It was found that [3H]glutamate uptake and release by hippocampal nerve endings, when measured 24 h after 1 h of acute restraint, presented no significant difference. The exposure to repeated restraint stress for 40 days increased neuronal presynaptic [3H]glutamate uptake as well as basal and K+-stimulated glutamate release when measured 24 h after the last stress session. Chronic treatment also caused a significant decrease in [3H]glutamate binding to hippocampal membranes. We suggest that changes in the glutamatergic system are likely to take part in the mechanisms involved in nervous system plasticity following repeated stress exposure.     

The proteoglycan Trol controls the architecture of the extracellular matrix and balances proliferation and differentiation of blood progenitors in the Drosophila lymph gland

The heparin sulfate proteoglycan Terribly Reduced Optic Lobes (Trol) is the Drosophila melanogaster homolog of the vertebrate protein Perlecan. Trol is expressed as part of the extracellular matrix (ECM) found in the hematopoietic organ, called the lymph gland. In the normal lymph gland, the ECM forms thin basement membranes around individual or small groups of blood progenitors. The pattern of basement membranes, reported by Trol expression, is spatio-temporally correlated to hematopoiesis. The central, medullary zone which contain undifferentiated hematopoietic progenitors has many, closely spaced membranes. Fewer basement membranes are present in the outer, cortical zone, where differentiation of blood cells takes place. Loss of trol causes a dramatic change of the ECM into a three-dimensional, spongy mass that fills wide spaces scattered throughout the lymph gland. At the same time proliferation is reduced, leading to a significantly smaller lymph gland. Interestingly, differentiation of blood progenitors in trol mutants is precocious, resulting in the break-down of the usual zonation of the lymph gland. which normally consists of an immature center (medullary zone) where cells remain undifferentiated, and an outer cortical zone, where differentiation sets in. We present evidence that the effect of Trol on blood cell differentiation is mediated by Hedgehog (Hh) signaling, which is known to be required to maintain an immature medullary zone. Overexpression of hh in the background of a trol mutation is able to rescue the premature differentiation phenotype. Our data provide novel insight into the role of the ECM component Perlecan during Drosophila hematopoiesis.     

Prevalence and predictors of exclusive breastfeeding among women in Kilimanjaro region,Northern Tanzania: a population based cross-sectional study

Background

Exclusive breastfeeding (EBF) is a simple and cost-effective intervention to improve child health and survival. Effective EBF has been estimated to avert 13% - 15% of under-five mortality and contribute to reduce mother to child transmission of HIV. The prevalence of EBF for infant less than six months is low in most developing countries, including Tanzania (50%). While the Tanzania Demographic Health Survey collects information on overall EBF prevalence, it does not evaluate factors influencing EBF. The aim of this paper was to determine the prevalence and predictors of exclusive breastfeeding in urban and rural areas in Kilimanjaro region.

Methods

A population-based cross-sectional study was conducted between June 2010 to March 2011 among women with infants aged 6–12 months in Kilimanjaro. Multi-stage proportionate to size sampling was used to select participants from all the seven districts of the region. A standardized questionnaire was used to collect socio-demographic, reproductive, alcohol intake, breastfeeding patterns and nutritional data during the interviews. Estimation on EBF was based on recall since birth. Multivariable logistic regression was used to obtain independent predictors of EBF.

Results

A total of 624 women participated, 77% (483) from rural areas. The prevalence of EBF up to six months in Kilimanjaro region was 20.7%, without significant differences in the prevalence of EBF up to six months between urban (22.7%) and rural areas (20.1%); (OR?=?0.7, 95% CI 0.5,1.4).In multivariable analysis, advice on breastfeeding after delivery (Adjusted odds ratio, AOR?=?2.6, 95% CI 1.5, 4.6) was positively associated with EBF up to six months. Compared to married/cohabiting and those who do not take alcohol, single mothers (AOR?=?0.4, 95% CI 0.2, 0.9) and mothers who drank alcohol (AOR?=?0.4, 95% CI 0.3, 0.7) had less odds to practice EBF up to six months.

Conclusion

Prevalence of EBF up to six months is still low in Kilimanjaro, lower than the national coverage of 50%. Strengthening of EBF counseling in all reproductive and child health clinics especially during antenatal and postnatal periods may help to improve EBF rates.