bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting population responses to restoration of breeding habitat in Atlantic salmon
Authors: Einum Sigurd , Nislow Keith H. , Reynolds John D. , Sutherland William J. 
Published: February 2008

SummaryHabitat degradation is seriously threatening stream biodiversity and productivity world‐wide. For salmonid fish, restoration projects in disturbed systems commonly aim at increasing the availability of suitable breeding habitats, but expectations of effects on population abundance based on explicit models are lacking.We used a spatial population model to predict how breeder dispersion may influence population dynamics of salmonids. Simulations involved changing the relative abundance of habitat suitable for two juvenile size classes (small fry and larger parr), the type of density‐dependent regulation (effects on survival only vs. effects on survival and growth) and intercohort competitive mechanisms.Increased breeding dispersion could alter patterns of density‐dependent mortality and increase equilibrium adult abundance and maximum sustainable yield (MSY). However, there was a strong interaction between stage‐specific habitat abundance and breeding dispersion. The most pronounced effects of breeding dispersion were observed under intermediate levels of fry habitat abundance.When fry habitat was abundant, density‐dependent mortality was most intense during the parr stage, and increased breeding dispersion did not increase adult abundance or MSY. In fact, when populations were regulated in the parr stage, increased breeding dispersion could cause decreased adult abundance because of the effects of intercohort competition. This negative effect only occurred, however, when competition among juveniles was symmetric (no age or size advantage).Synthesis and applications.The population effects of restoring breeding habitat can differ among environments, and we have demonstrated how these differences can be understood in the light of stage‐specific density dependence. Increasing spatial dispersion of breeders may often be an efficient measure for conserving threatened populations and increasing yields in fished populations. However, if direct evidence or habitat considerations suggest that fish populations experience density‐dependent mortality during the parr stage, attempts to increase abundance through increased breeding distribution or artificial stocking should be avoided, as these are likely to be ineffective or even detrimental. The difference between fishing rates providing maximum sustainable yield and extinction is particularly small for such populations, suggesting that fish managers should adopt a conservative and flexible regulation regime.
The epidemiology of obesity: the size of the problem
Authors: James W. P. T. 
Published: February 2008

Abstract.The epidemic of obesity took off from about 1980 and in almost all countries has been rising inexorably ever since. Only in 1997 did WHO accept that this was a major public health problem and, even then, there was no accepted method for monitoring the problem in children. It was soon evident, however, that the optimum population body mass index is about 21 and this is particularly true in Asia and Latin America where the populations are very prone to developing abdominal obesity, type 2 diabetes and hypertension. These features are now being increasingly linked to epigenetic programming of gene expression and body composition in utero and early childhood, both in terms of fat/lean tissue ratios and also in terms of organ size and metabolic pathway regulation. New Indian evidence suggests that insulin resistance at birth seems linked to low birth weight and a higher proportion of body fat with selective B12 deficiency and abnormalities of one carbon pool metabolism potentially responsible and affecting 75% of Indians and many populations in the developing world. Biologically there are also adaptive biological mechanisms which limit weight loss after weight gain and thereby in part account for the continuing epidemic despite the widespread desire to slim. Logically, the burden of disease induced by inappropriate diets and widespread physical inactivity can be addressed by increasing physical activity (PA), but simply advocating more leisure time activity is unrealistic. Substantial changes in urban planning and diet are needed to counter the removal of any every day need for PA and the decades of misdirected food policies which with free market forces have induced our current ‘toxic environment’. Counteracting this requires unusual policy initiatives.
Automated assessment of keratocyte density in clinical confocal microscopy of the corneal stroma
Authors: McLAREN J. W. , PATEL S. V. , NAU C. B. , BOURNE W. M. 
Published: February 2008

SummaryCell density in the corneal stroma is typically determined by counting the number of bright objects, presumably keratocyte nuclei, in images from clinical confocal microscopy. We present a program that identifies bright objects and counts those that most likely represent cells. Selection variables were determined from 125 normal corneas with cell densities that had been assessed manually. The program was tested on 17 corneas of patients before and at several intervals to 5 years after laser in situ keratomileusis (LASIK) surgery. In these corneas, which showed a decrease in cell density after surgery, the program identified cells as well as human observers did.
Raster image correlation spectroscopy (RICS) for measuring fast protein dynamics and concentrations with a commercial laser scanning confocal microscope
Authors: BROWN C. M. , DALAL R. B. , HEBERT B. , DIGMAN M. A. , HORWITZ A. R. , GRATTON E. 
Published: February 2008

SummaryRaster image correlation spectroscopy (RICS) is a new and novel technique for measuring molecular dynamics and concentrations from fluorescence confocal images. The RICS technique extracts information about molecular dynamics and concentrations from images of living cells taken on commercial confocal systems. Here we develop guidelines for performing the RICS analysis on an analogue commercial laser scanning confocal microscope. Guidelines for typical instrument settings, image acquisition settings and analogue detector characterization are presented. Using appropriate instrument/acquisition parameters, diffusion coefficients and concentrations can be determined, even for highly dynamic dye molecules in solution. Standard curves presented herein demonstrate the ability to detect protein concentrations as low as ∼ 2 nM. Additionally, cellular measurements give accurate values for the diffusion of paxillin‐enhanced‐green fluorescent protein (EGFP), an adhesion adaptor molecule, in the cytosol of the cell and also show slower paxillin dynamics near adhesions where paxillin interacts with immobile adhesion components. Methods are presented to account for bright immobile structures within the cell that dominate spatial correlation functions; allowing the extraction of fast protein dynamics within and near these structures. A running average algorithm is also presented to address slow cellular movement or movement of cellular features such as adhesions. Finally, methods to determine protein concentration in the presence of immobile structures within the cell are presented. A table is presented giving guidelines for instrument and imaging setting when performing RICS on the Olympus FV300 confocal and these guidelines are a starting point for performing the analysis on other commercial confocal systems.
Substrate threading through the central pore of the Hsp104 chaperone as a common mechanism for protein disaggregation and prion propagation
Authors: Tessarz Peter , Mogk Axel , Bukau Bernd 
Published: February 2008

SummaryThe oligomeric AAA+ chaperone Hsp104 is essential for thermotolerance development and prion propagation in yeast. Thermotolerance relies on the ability of Hsp104 to cooperate with the Hsp70 chaperone system in the reactivation of heat‐aggregated proteins. Prion propagation requires the Hsp104‐dependent fragmentation of prion fibrils to create infectious seeds. It remained elusive whether both processes rely on common or different activities of Hsp104. Specifically, protein reactivation has been suggested to require a substrate threading activity of Hsp104 whereas fibril fragmentation may be mediated by a crowbar activity. Here we engineered an Hsp104 variant, HAP, which cooperates with the bacterial peptidase ClpP to form a novel proteolytic system. HAP threads aggregated model substrates as well as the yeast prion Sup35 through its central pore into associated ClpP. HAP variants that harbour a reduced threading activity were affected in both protein disaggregation and prion propagation, demonstrating that substrate threading represents the common mechanism for the processing of both substrate classes.
Tolerance to the antimicrobial peptide colistin in Pseudomonas aeruginosa biofilms is linked to metabolically active cells, and depends on the pmr and mexAB‐oprM genes
Authors: Pamp Sünje Johanna , Gjermansen Morten , Johansen Helle Krogh , Tolker‐Nielsen Tim 
Published: February 2008

SummaryBacteria living as biofilm are frequently reported to exhibit inherent tolerance to antimicrobial compounds, and might therefore contribute to the persistence of infections. Antimicrobial peptides are attracting increasing interest as new potential antimicrobial therapeutics; however, little is known about potential mechanisms, which might contribute to resistance or tolerance development towards these compounds in biofilms. Here we provide evidence that a spatially distinct subpopulation of metabolically active cells in Pseudomonas aeruginosa biofilms is able to develop tolerance to the antimicrobial peptide colistin. On the contrary, biofilm cells exhibiting low metabolic activity were killed by colistin. We demonstrate that the subpopulation of metabolically active cells is able to adapt to colistin by inducing a specific adaptation mechanism mediated by the pmr operon, as well as an unspecific adaptation mechanism mediated by the mexAB‐oprM genes. Mutants defective in either pmr‐mediated lipopolysaccharide modification or in mexAB‐oprM‐mediated antimicrobial efflux were not able to develop a tolerant subpopulation in biofilms. In contrast to the observed pattern of colistin‐mediated killing in biofilms, conventional antimicrobial compounds such as ciprofloxacin and tetracycline were found to specifically kill the subpopulation of metabolically active biofilm cells, whereas the subpopulation exhibiting low metabolic activity survived the treatment. Consequently, targeting the two physiologically distinct subpopulations by combined antimicrobial treatment with either ciprofloxacin and colistin or tetracycline and colistin almost completely eradicated all biofilm cells.
Exploring the reasons why adolescents participate in physical activity and identifying strategies that facilitate their involvement in such activity
Authors: Ketteridge Asha , Boshoff Kobie 
Published: February 2008

Background:  Prompted by the dramatic rise in obesity and the decline in physical activity of adolescents aged 11–15 years, this study explored, from the participants’ viewpoints, the influences contributing to the engagement of adolescents in physical activities and the strategies facilitating their participation in physical activities. Methods:  An interpretive qualitative methodology was used involving 13 adolescents in three separate activity‐based focus groups. Results:  The findings describe the personal abilities of the participants and the health benefits, psychological, emotional and environmental factors influencing participation in physical activity. Findings endorse the use of supportive, enjoyable and skill‐appropriate approaches to physical activity intervention. Conclusions:  Implications for occupational therapy include promoting physical activities as aspects of occupations to improve the health and well‐being of adolescents through engagement in such activities.
MECHANICAL AND CIRCULATING BIOMARKERS IN ISOLATED CLINIC HYPERTENSION
Authors: Martin Catherine , Cameron James , McGrath Barry 
Published: February 2008

SUMMARY

This review examines the current evidence for altered mechanical and circulating biomarkers in isolated clinic hypertension and their potential significance.
Arterial stiffness, as assessed by central pulse wave velocity, is influenced by multiple cardiovascular risk factors; however, an independent association with isolated clinic hypertension (ICHT) has not been convincingly shown in four small studies.
Endothelial dysfunction, as assessed by brachial artery flow‐mediated vasodilation, circulating levels of endothelial markers (e.g. nitrite/nitrate, von Willebrand factor, endothelin‐1) and/or circulating levels of inhibitors of vascular nitric oxide (plasma asymmetric dimethylarginine, homocysteine), has been shown to be present in established hypertension and to a variable and inconsistent extent in subjects with ICHT.
Evidence of increased oxidative stress in ICHT versus normotensive subjects was found in two of three studies.
Circulating inflammatory markers C‐reactive protein and plasminogen activator inhibitor‐1 were significantly increased in two of three and two of two studies, respectively, in ICHT compared with normotensive subjects.
Urinary albumin excretion is a marker of both arterial and renal disease. The consensus from seven studies in patients with ICHT is that albuminuria is not an independent marker for ICHT.
Studies to date assessing biomarkers in ICHT have been small and cross‐sectional. Larger, long‐term longitudinal studies of arterial functional and circulating biomarkers are required to assess the potential vascular impact of ICHT.
ANGIOTENSIN CONVERTING ENZYME 2 IN THE KIDNEY
Authors: Koitka A , Cooper ME , Thomas MC , Tikellis C 
Published: February 2008

SUMMARYAngiotensin converting enzyme 2 (ACE2) is an important homeostatic component of the renin angiotensin system (RAS). ACE2 both degrades the vasoconstrictor, angiotensin II and generates the potent vasodilator peptide, angiotensin 1–7. These actions counterbalance those of ACE.ACE2 is highly expressed in the healthy kidney, particularly in the proximal tubules, where it colocalizes with ACE and angiotensin receptors.Kidney disease and subtotal nephrectomy is associated with a reduction in renal ACE2 expression, possibly facilitating the damaging effects of angiotensin II in the failing kidney. Acquired or genetic ACE2 deficiency also appears to exacerbate renal damage and albuminuria in experimental models, supporting this hypothesis.ACE2 also has an important role in blood pressure control. Many models of hypertension are associated with reduced ACE2 expression. AlthoughACE2KO animals are normotensive, in states associated with activation of the RAS, ACE2 overexpression improves blood pressure control and reduces angiotensin responsiveness.
CARDIOPROTECTION AND KALLIKREIN–KININ SYSTEM IN ACUTE MYOCARDIAL ISCHAEMIA IN MICE
Authors: Messadi‐Laribi E , Griol‐Charhbili V , Gaies E , Vincent MP , Heudes D , Meneton P , Alhenc‐Gelas F , Richer C 
Published: February 2008

SUMMARY

Acute myocardial ischaemia and reperfusion trigger cardioprotective mechanisms that tend to limit myocardial injury. These cardioprotective mechanisms remain for a large part unknown, but can be potentiated by performing ischaemic preconditioning or by administering drugs such as angiotensin‐I‐converting enzyme (kininase II) inhibitors (ACEI).
This brief review summarizes the findings concerning the role of tissue kallikrein (TK), a major kinin‐forming enzyme, kinins and kinin receptors in the cardioprotection afforded by ischaemic preconditioning (IPC) or by pharmacological postconditioning by drugs originally targeted at the renin–angiotensin system, ACEI and type 1 angiotensin‐II receptor blockers (ARB) in acute myocardial ischaemia. Myocardial ischaemia was induced by left coronary occlusion and was followed after 30 min by a 3 h reperfusion period (IR), performed in vivo in mice. The role of the kallikrein–kinin system (KKS) was studied by using genetically engineered mice deficient in TK gene and their wild‐type littermates, or by blocking B1 or B2 bradykinin receptors in wild‐type mice using selective pharmacological antagonists.
Ischaemic preconditioning (three cycles: 3 min occlusion/5 min reperfusion) enhances the ability of the heart of wild‐type mice to tolerate IR. Tissue kallikrein plays a major role in the cardioprotective effect afforded by IPC, which is largely reduced in TK‐deficient mice. The B2 receptor is the main kinin receptor involved in the cardioprotective effect of IPC.
Tissue kallikrein is also required for the cardioprotective effects of pharmacological postconditioning with ACEI (ramiprilat) or ARB (losartan), which are abolished for both classes of drugs in TK‐deficient mice. The B2 receptor mediates the cardioprotective effects of these drugs. Activation of angiotensin‐II type 2 (AT2) receptor is involved in the cardioprotective effects of losartan, suggesting a functional coupling between AT2 receptor and TK during angiotensin‐II type 1 (AT1) receptor blockade.
The demonstration of a cardioprotective effect of the KKS in acute myocardial ischaemia involving TK and the B2 receptor and playing a major role in IPC or pharmacological postconditioning by ACEI or ARB, suggests a potential therapeutic approach based on pharmacological activation of the B2 receptor.
SINGLE‐UNIT SYMPATHETIC DISCHARGE PATTERN IN PATHOLOGICAL CONDITIONS ASSOCIATED WITH ELEVATED CARDIOVASCULAR RISK
Authors: Lambert Elisabeth , Dawood Tye , Schlaich Markus , Straznicky Nora , Esler Murray , Lambert Gavin 
Published: February 2008

SUMMARY

Although measuring the rate of firing of multi‐unit muscle sympathetic nerve activity (MSNA) has provided important information in many aspects of cardiovascular medicine, measuring single‐unit vasoconstrictor activity provides a better understanding of the possible mechanisms underlying disturbed sympathetic nervous system activity.
Detailed firing patterns of sympathetic vasoconstrictor neurons have been recorded in conditions associated with sympathoexcitation such as heart failure, obstructive sleep apnoea syndrome, hypertension and obesity; conditions in which cardiovascular morbidity and mortality are demonstrably elevated.
Moreover, in conditions such as anxiety disorders and depression, in which elevated cardiovascular risk has recently been established, single‐unit analysis has highlighted a disturbed sympathetic firing pattern, which could not be identified on multi‐unit MSNA recording. This disturbed sympathetic nerve firing pattern, characterized by increased incidence of multiple firing within a sympathetic burst, has deleterious consequences on the cardiovascular system.
Single‐unit methodology may represent a major step forward in the understanding of the link between disturbed sympathetic nerve firing and associated cardiovascular risk.
UNDERSTANDING THE MORNING RISE IN BLOOD PRESSURE
Authors: Head Geoffrey A , Lukoshkova Elena V 
Published: February 2008

SUMMARY

The morning period has been recognized as the highest risk period of the day for cardiovascular events, particularly stroke and is also associated with a rapid surge in blood pressure.
Evidence now exists to show that the morning surge in blood pressure is an independent risk factor in some elderly hypertensive subjects.
However, methods to assess the contribution of the morning blood pressure surge from ambulatory recordings or home recordings, using clock times or times of waking, do not take into consideration the individual patterns of blood pressure change which can range from a rapid rise prior to or following waking to a slow increase over several hours.
In the present review we describe a novel method for determining the individual changes using a double logistic equation fitted to the individual pattern of blood pressure change.
Methods are presented to determine the rate of rise function over the morning period as well as predicting the change over a fixed time window which may be useful in refining the contribution of the blood pressure surge to cardiovascular risk.
Hypertensive people have an exaggerated rise in morning blood pressure as well as a greater rate of rise.
Antihypertensive drugs and dosing regimes are being developed which may be useful adjuncts to standard therapy for preventing morning hypertension and hopefully also reducing cardiovascular damage or events.
Variations in leaf stomatal density and distribution of 53 vine species in Japan
Authors: TAY AI‐CHEN , FURUKAWA AKIO 
Published: February 2008

AbstractTo determine variations in stomatal density and distribution in individual leaves of vine species with different growth/life forms and different habitat types, we quantified and compared leaf‐area‐based stomatal density, epidermal cell density and stomatal index (percentage of stoma on the epidermis to the total cell number, including epidermal and stomatal cells on the epidermis) of 53 species comprising 19 woody species (lianas) and 34 herbaceous vines growing in Japan. We counted the numbers of stomata on both the adaxial and abaxial leaf surfaces using a light microscope. Stomatal density and distribution on the leaf surfaces varied greatly among species. Most of the creeping herbaceous species had stomata on both the adaxial and abaxial leaf surfaces (amphistomatous); however, lianas had no stomata on the adaxial leaf surface. Species from coastal (probably drier) habitats had greater adaxial to abaxial ratios of stomatal density and stomatal indices compared with species from inland habitats. A positive correlation between stomatal density and epidermal cell density was found on the abaxial/adaxial leaf surfaces of the examined species. This suggests that there is a developmental similarity among vine species in which stomata are developed with differentiation of epidermal cells on the leaf surface. Thus, leaf stomatal density and distribution appear to vary among species with different growth/life forms from different habitats under a developmental constraint of leaf surface in vine plants in Japan.