bluuebunny/crossref_metadata_2025 huggingface dataset:
Resource competition and fire‐regulated nutrient demand in carnivorous plants of wet pine savannas
Authors: Brewer J. Stephen
Published: February 2009

Question: What are the mechanisms by which fire reduces competition for both a short‐lived and a long‐lived species in old‐growth ground‐cover plant communities of wet pine savannas (originally Pinus palustris, replaced by P. elliottii)?

Location: Outer coastal plain of southeastern Mississippi, USA.

Methods: I reviewed previous competition experiments and proposed a new hypothesis to explain the relationship between fire, competition, and species co‐existence in wet longleaf pine savannas. The first study is about growth and seedling emergence responses of a short‐lived carnivorous plant, Drosera capillaris, to reduction in below‐ground competition and above‐ plus below‐ground competition. The second study deals with growth and survival responses of a long‐lived perennial carnivorous plant, Sarracenia alata, to neighbour removal and prey‐exclusion to determine if a reduction in nutrient supply increased the intensity of competition in this nutrient‐poor system.

Results: Fire increased seedling emergence of the short‐lived species by reducing above‐ground competition through the destruction of above‐ground parts of plants and the combustion of associated litter. Prey exclusion did not increase competitive effects of neighbours on the long‐lived species. However, because the experiment was conducted in a year without fire, shade reduced nutrient demand, which may have obviated competition for soil nutrients between Sarracenia alata and its neighbours.

Conclusion: Repeated fires likely interact with interspecific differences in nutrient uptake to simultaneously reduce both above‐ground competition and competition for nutrients in old‐growth ground cover communities in pine savannas. Restoration practitioners should consider the possibility that the composition of the plant community is just as important as fire in ensuring that frequent fires maintain species diversity.
Grazing without grasses: Effects of introduced livestock on plant community composition in an arid environment in northern Patagonia
Authors: Tadey Mariana
Published: February 2009

Question: How does grazing intensity affect plant density, cover and species richness in an Patagonian arid ecosystem?

Location: Monte steppe ecoregion, SW Argentina.

Methods: I analysed the effect of grazing on plant density, cover and species richness using a stocking rate gradient within the same habitat. Six paddocks were used with stocking rates ranging between 0.002 – 0.038 livestock/ha. Plant density, species richness, plant cover and percentage of grazed branches were determined by sampling plots within each paddock. The percentage of grazed branches was used as an independent measurement of grazing intensity.

Results: Higher stocking rates were related to lower plant density, species richness and plant cover. The paddock with the lowest grazing intensity had 86% more plants per unit area, 63% more plant cover and 48% higher species richness. The percentage of grazed branches and the quantity of dung increased with stocking rate.

Conclusions: Introduced livestock seriously affect native vegetation in the Patagonian Monte. The damage observed in this xerophytic plant community suggests that plant adaptations to aridity do not provide an advantage to tolerate or avoid grazing by vertebrate herbivores in this region. Plant degradation in this arid environment is comparable to the degradation found in more humid ecosystems.
Effects of pioneer shrubs on the recruitment of the fleshy‐fruited tree Olea europaea ssp. cuspidata in Afromontane savanna
Authors: Aerts Raf , November Eva , Van der Borght Ives , Behailu Mintesinot , Hermy Martin , Muys Bart
Published: February 2009

Question: Is seedling recruitment of a fleshy‐fruited tree in degraded Afromontane savanna dependent on shelter from pioneer shrubs, and is shelter availability related to shrub traits?

Location: Degraded montane savanna in northern Ethiopia (13°36′N, 39°21′E).

Method: Nurse plants of Olea europaea ssp. cuspidata seedlings were recorded using T‐square plotless sampling and clustered according to shrub traits, using Ward's method after Principal Components Analysis. Facilitation was further examined through experimental planting and Kaplan‐Meier survival analysis.

Results: Both in grazed and protected areas, Olea recruits were found exclusively under shrubs, primarily under Euclea racemosa although Acacia etbaica was more abundant. Olea recruitment is distributed randomly at landscape scale, but depends on shelter at patch scale. Shelter ability is related to shrub shape and species identity. Dense multi‐stemmed shrubs with a wide base and crown on a mulch‐rich mound are key recruitment foci. Euclea shrubs have these favoured traits and probably act as preferential perching sites for avian seed dispersers. Soil and organic matter accumulation under Euclea shrubs may also create favourable conditions for Olea germination and survival. Experimentally planted seedlings had a better chance for survival under Euclea.

Conclusions: Olea regeneration is probably subject to both passive (disperser‐mediated) and active facilitation. Small changes of shrub traits can alter the suitability of a patch for Olea recruitment. Protection of shrubs can increase facilitation for seedlings, while pruning may reduce competition for saplings and thus enhance forest succession. Planting of raised Olea seedlings under Euclea shrubs in years with a good rainy season may further assist forest restoration.
Effects of the litter layer of Pteridium aquilinum on seed banks under experimental restoration
Authors: Ghorbani J. , Le Duc M.G. , McAllister H.A. , Pakeman R.J. , Marrs R.H.
Published: February 2009

Questions: Does the litter layer of Pteridium aquilinum (bracken) act as a barrier to certain species in the seed bank? Does bracken control/restoration treatment affect seed transfer through the litter layer?

Location: Five experiments at three sites across the UK covering two major vegetation types; acid‐grassland and heath‐land.

Methods: At each experiment a range of bracken control and vegetation restoration treatments were applied for about ten years. The seed bank was sampled in both the bracken litter and the soil. The cover (%) of each species in the vegetation and the bracken litter abundance (cover and depth) was also estimated.

Results: The bracken litter layer acts as an inert barrier as it contained a large proportion of seeds available in the litter‐soil profile (38%– 67% of the total). Bracken litter depth and cover also influenced significantly the seed bank composition in both the bracken litter and the soil. These effects were site‐specific, and species‐specific. The application of treatments changed significantly the balance between seed inputs and outputs in the bracken litter layer for some species. This was either a positive or negative response relative to the untreated control plots.

Conclusion: For heathland and acid‐grassland restoration, the bracken litter layer may be an important seed source, but it must be disturbed particularly before seed addition.
Fens and floodplains of the temperate zone: Present status, threats, conservation and restoration
Authors: van Diggelen Rudy , Middleton Beth , Bakker Jan , Grootjans Ab , Wassen Martin
Published: February 2009

Abstract. This Special Feature focuses on lowland fens and flood plains. In this introduction we discuss the most important mire‐related terms, present status, threats and conservation and restoration attempts. Floodplains and especially lowland fens are rare and vulnerable ecosystems. They are highly threatened all over the world because of direct conversion to agricultural land and especially the lack of appropriate management and altered catchment hydrology. Finally we present a framework for the conservation and restoration of these ecosystems. This consists of (1) optimising abiotic conditions; (2) safeguarding propagule availability of the target species; (3) creating and maintaining conditions for (re)establishment of these species, and (4) appropriate management to keep the conditions suitable.
Restoration of peat‐forming vegetation by rewetting species‐poor fen grasslands
Authors: Timmermann Tiemo , Margóczi Katalin , Takács Gábor , Vegelin Kees
Published: February 2009

Questions: Does succession of rewetted species‐poor fen grasslands display similar trends when different water levels, sites and regions are compared? Will restoration targets as peat growth and waterfowl diversity be reached?

Location: Valley fen of the river Peene (NE‐Germany) and the Hanság fen (Lake Neusiedler See, NW‐Hungary).

Methods: Analysis of permanent plot data and vegetation maps over a period of up to seven years of rewetting. The general relations between newly adjusted water levels and changes in dominance of helophytic key species during early succession are analysed considering four rewetting intensities (water level classes) and eight vegetation types (Phalaris arundinacea type, Carex type, Glyceria maxima type, Phragmites australis type, Typha type, aquatic vegetation type, open water type and miscellaneous type).

Results: The initial period of balancing the site conditions and vegetation is characterised by specific vegetation types and related horizontal vegetation structures. Most vegetation types displayed similar trends within the same water level class when different sites and regions were compared. A significant spread of potentially peat forming vegetation with dominance of Carex spp. or Phragmites as desired goal of restoration was predominantly restricted to long‐term shallow inundated sites (water level median in winter: 0–30 cm above surface). Open water patches as bird habitats persisted mainly at permanent inundated sites (water level median in winter > 60 cm above surface).

Conclusions: Site hydrology appeared as a main force of secondary succession. Thus the rewetting intensity and restoration targets have to be balanced adequately.
Plant traits in response to raising groundwater levels in wetland restoration: evidence from three case studies
Authors: van Bodegom P.M. , Grootjans A.P. , Sorrell B.K. , Bekker R.M. , Bakker C. , Ozinga W.A.
Published: February 2009

Question: Is raising groundwater tables successful as a wetland restoration strategy?

Location: Kennemer dunes, The Netherlands; Moksloot dunes, The Netherlands and Bullock Creek fen, New Zealand.

Methods: Generalizations were made by analysing soil dynamics and the responsiveness of integrative plant traits on moisture, nutrient regime and seed dispersal in three case studies of re wetted vs. control wetlands with the same actual groundwater levels. Soil conditions included mineral (calcareous and non‐calcareous) soils with no initial vegetation, mineral soils with established vegetation and organic soils with vegetation.

Results: The responsiveness of traits to raised groundwater tables was related to soil type and vegetation presence and depended on actual groundwater levels. In the moist‐wet zone, oligotrophic species, ‘drier’ species with higher seed longevity occupied gaps created by vegetation dieback on rewetting. The other rewetted zones still reflected trait values of the vegetation prevalent prior to rewetting with fewer adaptations to wet conditions, increased nutrient richness and higher seed longevity. Moreover, ‘eutrophic’ and ‘drier’ species increased at rewetted sites, so that these restored sites became dissimilar to control wetlands.

Conclusions: The prevalent traits of the restored wetlands do not coincide with traits belonging to generally targeted plant species of wetland restoration. Long‐term observations in restored and control wetlands with different groundwater regimes are needed to determine whether target plant species eventually re vegetate restored wetlands.
Wind dispersal in freshwater wetlands: Knowledge for conservation and restoration
Authors: Soons Merel B.
Published: February 2009

Questions: For wetland plants, dispersal by wind is often overlooked because dispersal by water is generally assumed to be the key dispersal process. This literature review addresses the role of seed dispersal by wind in wetlands. Why is wind dispersal relevant in wetlands? Which seeds are dispersed by wind and how far? And how can our understanding of wind dispersal be applied to wetland conservation and restoration?

Methods: Literature review.

Results and conclusions: Wind is a widely available seed dispersal vector in wetlands and can transport many seeds over long distances. Unlike water, wind can transport seeds in all directions and is therefore important for dispersal to upstream wetlands and to wetlands not connected by surface water flows. Wind dispersal transports seeds to a wider range of sites than water, and therefore reaches more sites but with lower seed densities.

Many wetland plant species have adaptations to facilitate wind dispersal. Dispersal distances increase with decreasing falling velocity of seeds, increasing seed release height and selective release mechanisms. Depending on the adaptations, seeds may be dispersed by wind over many km or only a few m. The frequency of long‐distance wind dispersal events depends on these adaptations, the number of produced seeds, the structure of the surrounding vegetation, and the frequency of occurrence of suitable weather conditions.

Humans reduce the frequency of successful long‐distance wind dispersal events in wetlands through wetland loss and fragmentation (which reduce the number and quality of seeds) and eutrophication (which changes the structure of the vegetation so that seed release into the wind flow becomes more difficult). This is yet another reason to focus on wetland conservation and restoration measures at increased population sizes, prevention of eutrophication, and the restoration of sites at short distances from seed sources.
A field assessment of the success of moorland restoration in the rehabilitation of whole plant assemblages
Authors: Littlewood N.A. , Pakeman R.J. , Woodin S.J.
Published: February 2009

Question: How successful is restoration that is focused on a single dominant plant at enabling the reassembly of the whole vegetation assemblage and what factors affect the relative success of such restoration?

Location: Moorlands in England and Scotland, UK.

Methods: Vegetation composition was sampled in grassdominated (degraded), restored and long established Calluna vulgaris‐dominated (target) areas within eight moorland restoration sites. Additional soil and biogeographic data were collected. Data were analysed by Canonical Correspondence Analysis, which allowed the impact of moorland management to be examined.

Results: All sites showed good restoration success when the dominant managed species (Calluna vulgaris, Molinia caerulea and Nardus stricta) were considered. Restoration success of the remainder of the plant assemblage, disregarding these dominant species, was lower with restored samples at some sites differing little from their respective degraded samples. Moors restored solely by grazing exclusion were more similar to their respective targets than were those restored by more intensive mechanical means. The most important factors in explaining vegetation assemblages were management status (i.e. whether samples represented degraded, restored or target parts of the moor) and latitude.

Conclusions: The project demonstrates that, where possible, restoration should be attempted by grazing exclusion alone. Furthermore the importance of applying local restoration targets and of monitoring the whole plant assemblages when assessing the success of moorland restoration is highlighted.
Biodiversity management of fens and fen meadows by grazing, cutting and burning
Authors: Middleton Beth A. , Holsten Bettina , van Diggelen Rudy
Published: February 2009

Question: Can the biodiversity of fens in Europe and North America be maintained through the use of grazing (especially cattle grazing), fire, and/or cutting?

Location: European and North American fens.

Methods: This paper is a review of the literature on the effects of grazing, fire and cutting on fens, to explore the relationship between management and biodiversity in fens.

Results: A reduction of cattle grazing, mowing and burning in fens has led to a reduction in biodiversity in fens. The vegetation of abandoned fens shifts to trees and shrubs after 10–15 years, which shade the smaller and rarer species of these wetlands. While careful use of fire is used to manage fens in North America, it is not widely used in European fens, perhaps because the peat of drained fens may catch fire. Cattle grazing cannot be considered a natural disturbance in North America, since cattle did not evolve on that continent. In Europe, cattle do not generally graze in unaltered fens, but they do use slightly drained fen meadows.

Conclusions: Three approaches have been used to control the dominance of tall woody and herbaceous species in abandoned fens, including the re‐introduction of cattle, mowing, and burning. Overgrazing results in a permanent reduction in biodiversity, therefore cattle re‐introduction must be approached cautiously. In Europe, but not in North America, mowing has been an important management tool, and mowing has been successful in maintaining species richness, particularly in fens that have been mowed annually for centuries. Fire has been the most common and successful management tool in North America although it is not effective in removing shrubs that have become large. Because the problems and solutions are similar, the literature of both European and North American fen management can be analyzed to better assess the management of fens on both continents. Many management questions require further study and these are listed in the paper.
A dendro‐ecological study of forest overstorey productivity following the invasion of the non‐indigenous shrub Lonicera maackii
Authors: Hartman K.M. , McCarthy B.C.
Published: February 2009

Question:Will a non‐indigenous, invasive, understorey shrub, such asLonicera maackii(Amur honeysuckle) have an impact on the productivity of overstorey trees in hardwood forests?

Location:Trees from 12 invaded and four non‐invaded sites were sampled in hardwood forests of southwestern Ohio, US.

Methods:Changes in radial and basal area tree growth in the ten years prior toL. maackiiinvasion vs. ten years after invasion were examined using dendrochronological techniques. Intervention analysis was used to detect growth changes 25 years prior to and 25 years following invasion, and estimates of load impacts forL. maackiipopulation and biomass were also calculated.

Results:We found that the rate of radial and basal area growth of overstorey trees was reduced significantly in eleven out of twelve invaded sites. Non‐invaded sites did not exhibit this consistent pattern of reduced growth. For invaded vs. non‐invaded sites, the mean basal area growth was reduced by 15.8%, and the overall rate of basal area growth was reduced by 53.1%. Intervention analysis revealed that the first significant growth reductions were 6.25 ± 1.24 (mean ± SE) years after invasion with the greatest frequency of negative growth changes occurring 20 years after invasion. In invaded stands, 41% of trees experienced negative growth changes. In terms of invasive load estimates per 1000L. maackiiindividuals, radial tree growth was reduced by 0.56 mm.a−1, and basal area growth was reduced by 0.74 cm2.a−1, Given these findings, significant economic losses could occur in hardwood forests of Ohio.

Conclusions:To our knowledge, this is the first study using dendrochronological techniques to investigate the impact of a non‐indigenous, understorey plant on overstorey tree growth. Active management will likely be needed to maintain forest productivity inL. maackiiimpacted landscapes.
Effects of the expansion by Hippophaë rhamnoides on plant species richness in coastal dunes
Authors: Isermann Maike , Diekmann Martin , Heemann Sonja
Published: February 2009

Question: Is the expansion of Hippophaë rhamnoides in coastal dunes associated with a decline in plant species richness, and is this decline best described by a hump‐backed relationship between species number and shrub cover?

Location: Grey and yellow dunes on the East Frisian islands Spiekeroog and Norderney.

Methods: Total plant species richness as well as the number of herbaceous and cryptogam species were determined in 2001 using plots of 16 m2 size. We compared shrubland plots with varying cover of Hippophaë with neighbouring dune grassland plots without shrubs as reference sites. Soil samples were collected to determine the values of some important edaphic variables (pH, organic matter, nitrogen).

Results: The shrubland plots with Hippophaë had or tended to have lower soil pH and C/N ratios and higher contents of organic matter and nitrogen than the grassland plots. Total species richness was marginally significantly related to the cover of Hippophaë in a hump‐backed manner on both islands. The pattern was more pronounced for mosses and lichens than for herbaceous species. For all species groups on Spiekeroog and for the herbaceous species on Norderney, the hump‐backed relationship was much improved when using the difference in species number between shrubland and grassland plot as a dependent variable. Relationships could be improved by including the soil parameters as co‐variables. Species richness was highest at moderate levels of shrub expansion, while it was much reduced in very dense shrubland. The decrease in species number is caused by the decline in grassland species typical of the open dunes, including some rare taxa.

Conclusions: The expansion of Hippophaë rhamnoides is a serious threat to the plant species richness of open coastal dunes, and needs to be counteracted by management measures.
Effects of cutting and nitrogen deposition on biodiversity in Cantabrian heathlands
Authors: Calvo L. , Alonso I. , Marcos E. , De Luis E.
Published: February 2009

Questions: Does the diversity of heathland vegetation change when subjected to experimental disturbances such as cutting and nitrogen fertilization? Do changes in the vegetation structure negatively affect the regeneration of the dominant species Calluna vulgaris? Is cutting an alternative method of conserving the diversity and maintaining the structure of heathlands in the Cantabrian Mountains?

Location:
Calluna vulgaris heathlands on the southern slopes of the Cantabrian Mountain range, NW Spain.

Methods: A total of 60 plots were treated with different combinations of cutting and twice the estimated atmospheric deposition of nitrogen (56 kg‐N.ha−1.yr−1). The changes in the cover values of the species present were monitored over a five year study period. The cover values were used to calculate abundance and species richness.

Results: Fertilizing with nitrogen allows biodiversity to increase over time. However, the greatest biodiversity is associated with the cutting plus fertilization treatment, since cutting allows gaps to be opened that are easily colonized by pioneer annual species, while fertilization mainly favours an increase in the mean number of perennial herbs (graminoids and forbs). Increased perennial herb richness also corresponds to a rise in their cover values. The recovery of the dominant woody species in these communities, Calluna vulgaris, is not impeded by the increase in perennial herbs species' cover values.

Conclusions: In the Calluna vulgaris heathlands studied, cutting plus fertilization allowed an increase in biodiversity over time. No displacement of the dominant woody species, Calluna vulgaris, is observed due to the presence of the perennial herbs. Cutting patches of heathland is recommended as a mechanism for maintaining high vegetation diversity, when grazing is not possible.
The role of soil seed banks in the restoration of dry acidic dune grassland after burning of Ulex europaeus scrub
Authors: Bossuyt B. , Cosyns E. , Hoffmann M.
Published: February 2009

Question: Can the seed bank play a significant role in the restoration of plant communities of dry acidic dune grassland where fire has destroyed Ulex europaeus scrub?

Location: Northern French Atlantic coast.

Methods: One year after the fire, the seed bank and vegetation were sampled in 1 m × 1 m plots along three transects from the oldest scrub vegetation towards the grassland. Differences in species richness, seed density and contribution of ecological groups in the seed bank and vegetation along the transects were analysed.

Results: Seed density and species richness in the seed bank decreased significantly from the grassland towards the centre of the scrub vegetation; 50% of the seed bank consisted of core species of the target plant community, such as Carex arenaria, Aira praecox, Rumex acetosella and Agrostis capillaris. Seeds of these species were also found in the deeper soil layers beneath the oldest scrub vegetation, indicating that they can be considered to be long‐term persistent. Beneath the youngest scrub vegetation, seeds of rare satellite target species also occurred. However, no target species were established on the burned site after one year, resulting in a large discrepancy between seed bank and vegetation.

Conclusions: Although the seeds present in the soil indicate that restoration of the acidic grassland based on the seed bank is possible, additional management actions such as mowing and soil disturbance may be necessary to restrict resprouting of Ulex and to stimulate the germination of seeds of target species in the deeper soil layers.
Plant functional types and climatic change: Introduction
Authors: Woodward F. Ian , Cramer Wolfgang
Published: February 2009

Abstract. Plant functional types are a necessary device for reducing the complex and often uncharted characteristics of species diversity in function and structure when attempting to project the nature and function of species assemblages into future environments. A workshop was held to review the current methods commonly used for defining plant functional types, either globally or for particular biomes, and to compare them with the field experiences of specialists for specific biomes of the world. The methods fall into either an objective and inductive approach or a subjective and deductive approach. When the different methods were tested, it was generally found that the classification for one site or environment was not wholly applicable to a different site or environment. However, the degree of change which is necessary for adjustment between environments may not prove to be a major limitation in the use of functional types.
Plant functional types and disturbance dynamics – Introduction
Authors: McIntyre S. , Díaz Sandra , Lavorel Sandra , Cramer Wolfgang
Published: February 2009

Abstract. Plant functional traits and types are useful concepts in relation to disturbance responses of natural and managed ecosystems. To explore their applicability in greater depth, a set of 12 papers presents a broad range of issues from methodologies to the results of particular trait studies in the field, and modelling approaches. So far, empirical studies have only allowed us to identify a few functional traits that are consistently associated with disturbance. To determine the trait variations associated with climate, disturbance history and current disturbance regime as well as the interactions between these factors, global‐scale comparisons of numerous individual studies are required. Significant advances toward this ambitious goal are presented in these papers, and include: (1) the articulation of experimental and analytical methodologies for individual studies that could usefully contribute to a global comparison; (2) the identification of core traits that can be used in the further search for disturbance‐related traits common to a range of environments; (3) further information on vegetation response to disturbance in terms of trait representation, and the identification of attribute syndromes; (4) the identification of issues for modelling disturbance dynamics using functional types.
Phytosociological data give biased estimates of species richness
Authors: Chytrý Milan
Published: February 2009

Abstract.Large phytosociological data sets of three types of grassland and three types of forest vegetation from the Czech Republic were analysed with a focus on plot size used in phytosociological sampling and on the species‐area relationship. The data sets included 12975 relevés, sampled by different authors in different parts of the country between 1922 and 1999. It was shown that in the grassland data sets, the relevés sampled before the 1960s tended to have a larger plot size than the relevés made later on. No temporal variation in plot sizes used was detected in forest relevés.

Species‐area curves fitted to the data showed unnatural shapes, with levelling‐off or even decrease in plot sizes higher than average. This distortion is explained by the subjective, preferential method of field sampling used in phytosociology. When making relevés in species‐poor vegetation, researchers probably tend to use larger plots in order to include more species. The reason for this may be that a higher number of species gives a higher probability of including presumed diagnostic species, so that the relevé can be more easily classified in the Braun‐Blanquet classification system. This attitude of phytosociologists has at least two consequences: (1) in phytosociological data bases species‐poor vegetation types are underrepresented or relevés are artificially biased towards higher species richness; (2) the suitability of phytosociological data for species richness estimation is severely limited.
A study of microRNAs in silico and in vivo: emerging regulators of embryonic stem cells
Authors: Kim Kye‐Seong , Kim Jong S. , Lee Man R. , Jeong Hoe S. , Kim Jaesang
Published: February 2009

MicroRNAs (miRNAs) are noncoding regulatory RNAs that function via the degradation of target mRNAs and inhibition of translation. They are found widely in higher eukaryotic organisms, and in several species that have been closely examined, hundreds of miRNAs have thus far been discovered with mechanistically conserved, yet functionally diverse, roles necessary for the proper development, homeostasis and metabolism of the organisms. Mammalian cells produce miRNAs in a cell‐type‐specific manner and utilize them to regulate unique subsets of genes expressed in the host cells. This rule also appears to apply to the pluripotent embryonic stem cells, according to several recent studies that reported identification of specifically expressed miRNAs. Intense interest in these miRNAs stems in part from the possibility that they are one of the determinants of the salient characteristics of these cells: self‐renewal capacity and pluripotency. As functional data supporting this hypothesis are beginning to accumulate, it can be envisioned that miRNAs may be useful as molecular tools for manipulating ESCs. This review focuses on the recent discovery and functional characterization of miRNAs in human and mouse ESCs and provides perspectives on future research directions.
The Role of Chloride Channels in Rat Corpus Cavernosum: In Vivo Study
Authors: Kuo Yuh-Chen , Chung Shiu-Dong , Liu Shih-Ping , Chang Hong-Chiang , Yu Hong-Jeng , Hsieh Ju-Ton
Published: February 2009

Introduction

Recent studies have identified the existence of outward, depolarizing chloride currents in isolated rat, rabbit, and human corpus cavernosum muscle cells. However, few articles have demonstrated the functional role of chloride channels in vivo in corpus cavernosum smooth muscle.

Aim

To investigate the role of calcium-dependent chloride channels in erectile function of rat corpus cavernosum smooth muscle.

Methods

Adult male Wistar rats were used to perform an in vivo study in a rat model of erection. Both crura of the rats were isolated to in order to record intracavernosal pressure (ICP) during basal conditions and electrical stimulation of erection, with and without intracorporeal injection of norepinephrine, chloride transport inhibitors, and chloride channel blockers.

Main Outcome Measure

ICP.

Results

ICP increased as the amplitude of electrical stimulation increased, and decreased in a dose-dependent manner (during electrical stimulation) as norepinephrine injection strength increased. Injection into the corpus cavernosum of the Cl- channel blockers, niflumic acid, anthracene-9-carboxylic acid, and 4,4′-diisothiocyano-2,2′-stilbene-disulfonic acid increased ICP. Injection into the corpus cavernosum of the Cl- channel transport inhibitors bumetanide, ethacrynic acid, and HCO3-free 4-(2-hydroxyethyl )-1-1- piperazine ethanesulphonic acid buffer, and also increase the ICP. The effects of both Cl- channel blockers and Cl- channel transport inhibitors on ICP were concentration-dependent.

Conclusions

Our findings suggest that chloride channels play an important role in the regulation of corpus cavernous smooth muscle tone in vivo.
Clinical Autonomic Neurophysiology and the Male Sexual Response: An Overview
Authors: Yang Claire C. , Jiang Xiaogang
Published: February 2009

Introduction

Clinical neurophysiology is the study of the human nervous system through the recording of bioelectrical activity. In the realm of male sexual functioning, this includes using electrophysiologic techniques to study the nerves subserving erection, emission, ejaculation, and orgasm.

Aim

To introduce the reader to the principles of clinical neurophysiology as they relate to the male sexual response, particularly erection.

Methods

We review the pertinent autonomic neuroanatomy and neurophysiology of reflexes relevant to the male sexual response, as well as summarize the genital electrodiagnostic tests that are being used to interrogate the autonomic innervation pertinent to male sexual functioning.

Conclusions

The male sexual response is a coordinated series of interactions between the somatic and the autonomic nervous systems. Measurement of the autonomically mediated portions of the sexual reflexes is of great clinical interest, particularly in relation to erection. Advances in clinical electrodiagnostics now allow for consistent recording of evoked and spontaneous intrapenile electrical activity. However, before broad and widespread use of these techniques is possible, more investigations are needed.
Neural Regulation of Ejaculation
Authors: Young Brandt , Coolen Lique , McKenna Kevin
Published: February 2009

Introduction

Delineation of the underlying neurophysiological mechanisms of ejaculatory behavior is crucial for the treatment of male sexual dysfunction, including premature ejaculation. Recent studies provide compelling evidence that a population of lumbar spinothalamic (LSt) cells may play a role in the regulation of the ejaculatory response. Subsequent to ejaculation, LSt cells exhibit markers of activation that are not only highly correlated with ejaculatory behavior, but are also absent following the expression of other components of sexual behavior, such as mounts or intromissions. Similarly, targeted chemical lesion of LSt cells using substance P-saporin abolishes ejaculatory behavior explicitly. Early evidence suggests that pharmacological manipulation of LSt cells may offer additional evidence of crucial LSt cell involvement in the generation of ejaculation.

Aim

This review is intended to summarize what has currently been revealed regarding the role of LSt cells in the regulation and generation of ejaculatory behavior, and also to discuss the direction of future behavioral investigations.

Methods

Information presented in this discussion was derived from analysis of numerous recent articles detailing the delineation of anatomical and physiological correlates of sexual behavior, as well as numerous literature searches using the National Library of Medicine PubMed Services.

Results

A great deal of the work that has led to the implication of LSt cells in ejaculatory behavior is reviewed in the present article, including clinical data, as well as anatomical, physiological, and behavioral examinations. The rationale for ongoing pharmacological studies is also discussed.

Conclusion

LSt cells appear to play a vital role in the generation and regulation of ejaculatory behavior. Additional elucidation of this “ejaculation generator” could prove invaluable for the future treatment of male sexual dysfunction. Studies are currently in progress to further reveal the precise function of these cells and mechanisms of action through which they operate.
Sex Steroid Hormones in Diabetes-Induced Sexual Dysfunction: Focus on the Female Gender
Authors: Kim Noel N.
Published: February 2009

Introduction

Diabetes is associated with gender-specific changes in sex steroid hormones. However, the mechanisms responsible for these associations as well as the link to sexual dysfunction are not well understood.

Aim

To discuss key clinical and laboratory findings linking diabetes, sex steroid hormones, and sexual dysfunction, with particular focus on the female gender.

Methods

A comprehensive literature review was conducted using the PubMed database. Search terms were used in appropriate combinations, including diabetes, insulin, insulin sensitivity, androgen, estrogen, sexual function, women, men, estrogen receptor, and androgen receptor. Over 400 citations were selected, based on topical relevance, and examined for study methodology and major findings.

Main Outcome Measures

Data from peer-reviewed publications.

Results

Imbalances in sex steroid hormone levels are strongly associated with diabetes and this may negatively impact upon sexual function. Although numerous factors are likely to contribute to the development of diabetes and its complications, the role of sex steroid hormones must be acknowledged.

Conclusions

Research related to diabetic women and sexual dysfunction is severely lacking. Identifying underlying causes for a given hormonal imbalance in diabetic patients, as well as determination of genetic and age-dependent factors, will become important in identifying the subpopulations in which hormonal replacement regimens will be most effective. Investigation into treating diabetic patients with adjunct hormonal therapies or steroid hormone receptor modulators holds much promise.
Reversal of Voltage-Dependent Erectile Responses in the Zucker Obese-Diabetic Rat by Rosuvastatin-Altered RhoA/Rho-kinase Signaling
Authors: Wingard Christopher J. , Moukdar Fatiha , Prasad Raju Y. , Cathey Brook L. , Wilkinson Lois
Published: February 2009

Introduction

The combination of independent risk factors for erectile dysfunction, obesity, hypertension, and diabetes are collectively manifested in a condition known as metabolic syndrome X (MSX). However, the regulatory mechanisms responsible for the erectile dysfunction (ED) are not fully understood. Clinical studies suggest that a pleiotropic effect of statin’s ability to enhance vascular relaxation might be through an impact on nitric oxide signaling or through a regulation of RhoA activation.

Aim

We hypothesized that regulatory aspects of short-term statin therapy involve the alteration of the RhoA/Rho-kinase signaling cascade and will reverse the ED seen in a rat model of MSX.

Main Outcome Measures

The magnitude and sensitivity of the voltage-dependent maintenance of intracavernosal blood pressure and mean arterial blood pressure. These responses were correlated with tissue protein and mRNA expression levels of RhoA and Rho kinases.

Methods

Erectile function was evaluated by assessing voltage-dependent stimulation of the cavernosal nerve in 16–20 weeks old lean and obese-diabetic Zucker rats treated with 5 mg/kg/day of rosuvastatin intraperitoneally for 3 days. Cavernosal tissue RhoA and Rho-kinases expression levels were evaluated by real-time reverse transcriptase-polymerase chain reaction, Western blot.

Results

The voltage-dependent erectile responses were suppressed by >30% in the obese-diabetic Zucker rat. The 3-day treatment with rosuvastatin partially restored the erectile response. The Rho-kinase inhibitor, H-1152, dose dependently increased the erectile responses and shifted the voltage sensitivity with statin treatment. Analysis of protein expression levels suggested elevation of RhoA and Rho kinases in obese-diabetics and statin treatment lowering Rho-kinase II. The RhoA and Rho-kinase II mRNA levels were significantly reduced in the rosuvastatin-treated obese-diabetic animals.

Conclusions

These results support a hypothesis that short-term statin therapy may lower RhoA/Rho-kinase expression levels and improve cavernosal blood pressure response to Rho-kinase inhibition and voltage-stimulation, and reversing an augmented vasoconstricted state associated with diabetes and/or hypertension in MSX.
Sonic Hedgehog, Apoptosis, and the Penis
Authors: Podlasek Carol A.
Published: February 2009

Introduction

Smooth muscle apoptosis in the penis is common in prostatectomy patients and animal models of erectile dysfunction (ED). A critical regulator of smooth muscle apoptosis in the penis is the secreted protein Sonic hedgehog (SHH). Since SHH protein treatment of the penis prevents cavernous nerve (CN) injury-induced apoptosis, SHH has the potential to treat post-prostatectomy apoptosis. However, little is known about how SHH signaling is regulated in the adult penis.

Aim

The goal of this review is to examine what is known about SHH signaling in the penis, to offer insight as to how SHH inhibition induces apoptosis in penile smooth muscle, and to define the role of the SHH pathway in maintaining CN integrity.

Methods

Information presented in this review was derived from a literature search using the National Library of Medicine PubMed Services. Search terms included SHH, apoptosis, smooth muscle, penis, ED, pelvic ganglia, corpora cavernosa, CN, regeneration, Schwann cell, neural activity, and transport.

Results

In this review, we have discussed the role of the CN in regulation of SHH abundance and apoptosis induction in the penis, and have examined the function and localization of SHH signaling in the CN.

Conclusion

There is substantial potential to develop SHH for delivery to the penis of prostatectomy patients at the time of surgery in order to prevent apoptosis induction and long-term ED development. Studies are in progress that will identify if SHH may be used as a regenerative therapy to speed CN regeneration.
Mechanisms of Penile Fibrosis
Authors: Gonzalez-Cadavid Nestor F.
Published: February 2009

Introduction

Penile fibrosis has been conceptually identified with the plaque that develops in the tunica albuginea in Peyronie’s disease (PD), or with localized processes induced in the corpora cavernosa by ischemic or traumatic events. Recently, it has been proposed that a diffuse, progressive, and milder intracorporal fibrosis, which affects also the media of the penile arteries, is responsible for vasculogenic erectile dysfunction (ED) associated with aging, smoking, diabetes, hypertension, and post-radical prostatectomy. These processes differ in etiology, time course, target cells, and treatment, but have many features in common.

Aim

To review the literature pertaining to fibrosis in the penis, related to PD and ED.

Methods

PubMed search for pertinent publications mainly during 2001–2008.

Results

This review focuses initially on PD and then deals with studies on ED in animal and cell culture models, discussing some of the pathophysiological similarities between tunical fibrosis in PD and corporal fibrosis in corporal veno-occlusive dysfunction (CVOD), and emerging therapeutic strategies. The role of profibrotic factors, the excessive deposit of collagen fibers and other extracellular matrix, the appearance of a synthetic cell phenotype in smooth muscle cells or the onset of a fibroblast–myofibroblast transition, and in the case of the corporal or penile arterial tissue the reduction of the smooth muscle cellular compartment, are discussed. This histopathology leads either to localized plaques or nodules in penile tissues, or to the diffuse fibrosis causing impairment of tissue compliance that underlies CVOD and arteriogenic ED. The antifibrotic role of the sustained stimulation of the nitric oxide/cyclic guanosine monophosphate pathway in the penis and its possible relevance to exogenous and endogenous stem cell differentiation is also briefly presented.

Conclusions

Fibrotic processes in penile tissues share a similar cellular and molecular pathophysiology and common endogenous mechanisms of defense that have inspired novel pharmacological experimental approaches.
Continuing Medical Education: The Use of Estrogen Therapy in Women’s Sexual Functioning (CME)
Authors: Nappi Rossella E. , Polatti Franco
Published: February 2009

Introduction

Estrogen is relevant to women’s well-being including sexual functioning.

Aim

The goal of this Continuing Medical Education article was to provide a comprehensive review of the effect of exogenous estrogen use on women’s sexual function.

Main Outcome Measures

We present a literature review.

Methods

The medical literature was accurately searched (1990–2008) with regard to estrogen therapy in menopausal women by using several terms related to and including the terms “estrogen” and “sexual function.”

Results

A review of the studies most useful to guide menopausal practice.

Conclusions

Estrogen decline is one of the key factors contributing to sexual functioning during menopausal transition and beyond. Systemic estrogen treatments are associated with significant benefits in some domains of menopausal sexual function, especially when estradiol is delivered transdermally, whereas local estrogens are effective in preventing urogenital aging. Even tibolone, a selective tissue estrogenic activity regulator, displays positive effects in postmenopausal women with sexual complaints. However, a tailored approach to the individual woman is always needed.
Oral cavity squamous cell carcinomas in young patients in a selected Malaysian centre
Authors: AHMAD Hafeza , JABAR Nazimi A , RAHMAN Normastura A , RAHMAN Roslan A , SHA Primuharsa Putra , RAMLI Roszalina
Published: February 2009

Aim:  This study aims to evaluate the demographics, to analyze the clinical and pathological findings, treatment and the outcome of oral cavity squamous cell carcinomas (OSCC) in patients aged 40‐years old and below in our centre.

Methods:  Records of patients who were diagnosed with OSCC in the Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, from 1998 to 2003 were analyzed. Their socioeconomic data such as their age, gender and race, risk factors, family history and genetic predisposition were assessed. Other data examined included the sites and stage of the tumor, histopathology results, treatment modality and outcome of OSCC.

Results:  There were 19 patients with no gender predilection. Malays made up most patients diagnosed with OSCC, followed by Chinese and Indians. There was no significant high‐risk habit in this group. Most of the sites involved were the tongue (73.7%), buccal mucosa (15.8%) and alveolus (10.5%). Most of the patients (57.9%) were diagnosed with stage IV disease. Eighteen patients underwent treatment consisting of surgery or radiotherapy or in combination. A 5‐year follow up revealed that nine patients (47.3%) survived and remain well, four patients (21.1%) had a recurrence, two patients (10.5%) died of the disease.

Conclusion:  The majority of patients presented with stage IV disease without any significant high‐risk habit. Surgery remains the mainstay of treatment, however, 5‐year follow‐up showed a less than 50% survival rate.