bluuebunny/crossref_metadata_2025 huggingface dataset:
Explaining density‐dependent regulation in earthworm populations using life‐history analysis
Authors: Kammenga Jan E. , Spurgeon David J. , Svendsen Claus , Weeks Jason M.
Published: December 2004

At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life‐history patterns. We compared density dependent population consequences in the Nicholsonian sense based on experimental observations and life‐history modeling for the earthwormsLumbricus terrestrisandEisenia fetida. Both species differ in their life‐histories,L. terrestrisbeing a relatively long‐lived species with slow reproduction and occurring at low densities compared toE. fetidawhich has a more opportunistic strategy with a high reproductive output.E. fetidais able to colonise new habitats rapidly and may occur at relatively high population densities. Density dependency of population growth rate was estimated by incorporating density dependent effects on reproduction and growth using a modified Euler equation. The results point out thatE. fetidawas not as strongly impacted by density as compared toL. terrestris. Population growth rate inE. fetidawas hardly affected at low and moderate density, being reduced only at high level, this compares toL. terrestriswhere even relatively small density effects resulted in a strong negative effect on population growth rate. Our findings indicate that density‐dependent regulation in earthworms can be quantified using life‐history analysis. The outcomes are in agreement with empirical field observations for populations (i.e.L. terrestrisoccurs ar low density,E. fetidaat high density). Consideration of the potential importance of Nicholsonian density dependence for field populations of these two species in light of their known biology however produces counterintuitive conclusions. InE. fetida, although density tolerant, rapid population growth may mean this species may be subject to density dependeny regulation. InL. terrestris, although density sensitive, complex behavioural ecology (surface activity, territoriality) may limit of feedback influence on population size.
Hungry predators render predator‐avoidance behavior in tadpoles ineffective
Authors: Altwegg Res
Published: December 2004

Behavioral responses of prey to their predators can critically alter community dynamics. Whether or not a prey responds, clearly depends on the effectiveness of that response. The effectiveness on the other hand is predicted to depend on predator behavior. Actively searching predators can render the behavioral responses in their prey ineffective. Nevertheless, most studies investigating the optimal reaction of prey treated predators as immobile elements of the environment. I experimentally manipulated activity of poolfrog (Rana lessonae) tadpoles by keeping them at low and high food levels, and exposed them to three species of invertebrate predators (Aeshna cyanea, Anax imperator, andDytiscus marginalis), whose activity also was manipulated through different food levels. Satiated, less active predators were more likely to kill hungry, more active tadpoles, but hungry predators killed hungry and satiated tadpoles about equally often. This result suggests that reducing their activity is a more effective strategy for tadpoles if the predators themselves are less active. On the other hand, against hungry, highly motivated predators, the behavioral avoidance strategies were essentially ineffective. Antipredator behavior is generally thought to stabilize the dynamics of predator–prey systems. The results presented here, however, suggest that the community dynamical consequences of antipredator behavior also critically depend on decisions made by predators.
Population dynamics of rice rats (a Hantavirus reservoir) in southern Chile: feedback structure and non‐linear effects of climatic oscillations
Authors: Murúa Roberto , González Luz A. , Lima Mauricio
Published: December 2004

We studied a fluctuating population of the long‐tail rice rat (Oligoryzomys longicaudatus), the main Hantavirus vector in southern Chile, and spanning 19 years of monitoring. We determined that a first‐order feedback structure and non‐linear effects of Antarctic Oscillation Index (AAOI) and Southern Oscillation Index (SOI) explain 96% of the variation in annual per capita population growth rates. One important result of this study is that first‐order feedback structure captures the essential features of population dynamics of long‐tailed rice rats. This regulatory structure suggests that rice rats are limited by food, space or predators and regulated by intra‐specific competition. The first‐order dynamics observed in long‐tailed rice rats strongly suggests that Hantavirus have no harmful effects on survival or reproductive processes. Besides the non‐linear climatic signature in population dynamics, the periodic event of bamboo‐flowering and mast seeding strongly influence rice rats population growth rates. Because of this, bamboo flowering may be used as a signal for forecasting long‐tail rice rats outbreaks and for implementing information and health policies to avoid human‐rodent contacts in specific areas. The observed effects of the two large‐scale climatic indexes that influence climatic variability along southern Pacific Ocean, the AAOI and the SOI, emphasizes the role of considering non‐linear feedback structures and climatic forces for understanding small rodent population dynamics. Because long‐tailed rice rats represent the major Hantavirus reservoir in southern Chile and Argentina, we need to gain an in‐depth understanding of the structure and functioning of these small rodent populations in face of the potential consequences of global change and climatic fluctuations.
Forces structuring tree squirrel communities in landscapes fragmented by agriculture: species differences in perceptions of forest connectivity and carrying capacity
Authors: Goheen Jacob R. , Swihart Robert K. , Gehring Thomas M. , Miller Michael S.
Published: December 2004

The North American red squirrel (Tamiasciurus hudsonicus) has expanded its range into the central hardwoods of the United States in conjunction with increasing forest fragmentation and declining gray squirrel (Sciurus carolinensis) populations. We used translocation experiments and patch occupancy data to test for interspecific differences in mobility and sensitivity to habitat loss and modification by agriculture. We released squirrels in fencerows to test the hypothesis that gray squirrels display inferior mobility relative to red and fox (S. niger) squirrels. Elapsed time to movement from fencerows for 76 individuals increased with distance to forest patches and harvesting of crops. Gray and red squirrels took longer to move from fencerows than fox squirrels, and gray squirrels were less successful at moving from fencerows than red and fox squirrels. Ecologically scaled landscape indices revealed the degree to which interspecific differences in mobility and individual area requirements accounted for the occurrence of these species across landscapes. Gray squirrel distribution was constrained both by individual area requirements and dispersal ability. Occurrence of red and fox squirrels was related to patch size but was unaffected by landscape connectivity.
Timing an ontogenetic niche shift: responses of emerging salmon alevins to chemical cues from predators and competitors
Authors: Jones Mirkka , Laurila Anssi , Peuhkuri Nina , Piironen Jorma , Seppä Teija
Published: December 2004

Ontogenetic niche shifts are ubiquitous in nature. However, in most species little is known about phenotypic plasticity in the timing of shifts and in the associated characters. Following a period of endogenous feeding on yolk, salmonid alevins emerge from their gravel nests into the open water and start feeding exogenously. We studied, by using replicated artificial nests, whether the responses of emerging Atlantic salmon (Salmo salar) alevins to chemical cues from two piscivorous fish predators and conspecific competitors are plastic. We hypothesised that the alevins should delay emergence in response to predator cues, whereas cues from competitors should induce earlier emergence. We found that chemical cues from predatory burbot (Lota lota) delayed emergence, whereas cues from brown trout (S. trutta) tended to induce earlier emergence. The earlier emergence in response to trout cues was associated with a smaller body size and more yolk resources remaining at emergence, but burbot cues did not alter these traits. Predator cues also influenced the daily pattern of emergence: more alevins emerged during the morning in the burbot treatment, and fewer alevins emerged during the afternoon in the trout treatment. Chemical cues from conspecific competitors had no effect on emergence patterns. The results indicate that salmon alevins exhibit flexible ontogenetic niche shifts in the timing of emergence in response to predator cues, and that the responses are predator‐specific. As timing of emergence is a major determinant of territory acquisition, these responses are likely to have an impact on later fitness of the fry.
Temporally fluctuating prey and coexistence among unequal conspecific interferers
Authors: Nilsson P. Anders , Ruxton Graeme D. , Nilsson J. Håkan
Published: December 2004

Coexistence among unequal conspecific interferers should be unlikely to persist if stronger interferers always experience a relative fitness increment from their higher foraging rates. In this study, we suggest that decreased relative costs to weaker interferers with increasing temporal fluctuations in prey availability may be a mechanism enhancing coexistence of unequal conspecific interferers. Previous work on fluctuation and coexistence has dealt with oscillations over a time‐scale measured in generations of competitor species and their resources, while our work shows that fluctuations in prey availability facilitate coexistence of different phenotypic strategies within species and generations, and over short time‐scales. With increasing amplitude of temporal fluctuation about an average prey density, cumulative intakes for differently strong interferers are affected differently. Because of the prey‐dependent effect of interference, high amplitudes of fluctuation allow for relatively lower foraging‐rate costs in weaker interferers, which decreases the difference in foraging success between strong and weaker interferers. This decreased difference in foraging success could thus significantly relax the conditions allowing for unequal interferer coexistence.
An Antisense Strategy for Inhibition of Human Melanoma Growth Targets the Growth Factor Pleiotrophin
Authors: SATYAMOORTHY KAPAETTU , OKA MASAHIRO , HERLYN MEENHARD
Published: December 2004

A major biological characteristic of metastatic melanomas is their ability to survive in a growth‐factor‐depleted environment, whereas normal melanocytes die rapidly under such conditions. The increased survival of melanoma cells is due to their production of growth factors for autocrine growth stimulation. Here, we describe a strategy to inhibit pleiotrophin (PTN), a heparin‐binding autocrine growth factor for melanoma cells. To target PTN production in melanoma cells, a replication‐deficient, recombinant adenovirus was generated to express antisense (AS) PTN at high efficiency. The AS vector induced transcripts that completely inhibited PTN protein production. Melanoma growth was strongly inhibited if the tumor cells were maintained in a three‐dimensional environment in soft agar, whereas cell growth was not affected if the tumor cells were grown as a monolayer, suggesting the importance of cell–matrix interactions for the biological activity of this growth factor. The down‐regulation of PTN in transduced melanoma cells coincided with the down‐regulation of the cell‐cycle regulator cyclin E and the up‐regulation of the cell‐cycle inhibitor p21WAF1/Cip1. Tumor growth in vivo was also delayed by the AS‐PTN vector, confirming that PTN is essential for the three‐dimensional growth of tumor cells. Our studies demonstrate the importance of assessing potential melanoma antagonists not only on cells grown as monolayers but also in three‐dimensional matrices.
Tanning as Part of the Eukaryotic SOS Response
Authors: ELLER MARK S. , GILCHREST BARBARA A.
Published: December 2004

We have determined that DNA damage is at least one of the signals generated by ultraviolet radiation that stimulates pigmentation (tanning) in human skin. This photoprotective response is functionally similar to the SOS response described in bacteria. Here we present evidence that DNA damage stimulates pigmentation, at least in part, through up‐regulation of tyrosinase mRNA and protein levels. Furthermore, this response can be induced in the absence of DNA damage by treatment of melanocytic cells and intact skin with small DNA fragments, particularly thymidine dinucleotides, pTpT. Topical application of these DNA fragments should provide a photoprotective tan to human skin without the harmful effects of ultraviolet radiation.
Skin POMC Peptides: Their Actions at the Human MC‐1 Receptor and Roles in the Tanning Response
Authors: TSATMALI MARINA , ANCANS JANIS , YUKITAKE JUN , THODY ANTHONY J.
Published: December 2004

The melanocortin 1 (MC‐1) receptor is a key control point in the regulation of skin pigmentation. α‐MSH is an agonist at this receptor and through its activation regulates melanocyte function. α‐MSH is cleaved from pro‐opiomelanocortin (POMC) in the pituitary, but in humans the skin is a more important source of the peptide. Skin pigmentation is therefore regulated by locally produced α‐MSH rather than that of pituitary origin. α‐MSH acts as a paracrine and/or autocrine mediator of UV induced pigmentation. However, the predominant α‐MSH in human skin is desacetyl α‐MSH and, compared to the acetylated form, is a relatively weak agonist at the human MC‐1 receptor. By acting as a partial agonist desacetyl α‐MSH may even oppose the actions of acetylated α‐MSH and other MC‐1 receptor agonists. The most abundant MC‐1 receptor agonist in human epidermis is ACTH1‐17. This POMC peptide, which is produced by keratinocytes, is more potent than acetylated α‐MSH in stimulating melanogenesis in human melanocytes and, in contrast to the latter, produces a biphasic dose‐response curve. This is probably a consequence of its activation of both the cAMP and IP3/DAG signalling pathways. α‐MSH peptides, on the other hand, selectively activate the cAMP pathway. Compared with α‐MSH, ACTH1‐17 could have the more important role as a paracrine mediator of melanogenesis and other melanocytic processes. However, ACTH1‐17 is not the only POMC peptide in the skin and may interact with related peptides at the MC‐1 receptor. These interactions are likely to represent important determinants of melanocyte function and skin pigmentation.
Prolactin Signaling in Erythrophores and Xanthophores of Teleost Fish
Authors: OSHIMA NORIKO , GOTO MIYOSHI
Published: December 2004

Prolactin directly affects erythrophores and xanthophores of teleost fish, resulting in pigment dispersion. In the present study, signal transduction elicited by prolactin was examined using split‐tail fin preparations of the rose bitterling and Nile tilapia, and cultured erythrophores and xanthophores from the paradise goby and rose bitterling. When antibodies to the prolactin receptor were added to an ovine prolactin (oPRL) solution, pigment dispersion within cultured cells was significantly inhibited, suggesting the existence of a prolactin receptor in the cell membrane. In mammals and birds, prolactin receptors belong to a cytokine receptor superfamily and signal through a tyrosine kinase‐mediated pathway. Therefore, we examined the effects of three kinds of protein tyrosine kinase inhibitors on pigment dispersion elicited by oPRL. None of those inhibitors depressed the response. On the other hand, lithium ions (an inhibitor of adenylate cyclase) and H‐88 and H‐89 (inhibitors of protein kinase A) decreased the levels of oPRL‐induced pigment dispersion in a dose‐dependent manner. In cultured cells treated with cholera toxin for 3 hrs, the effect of oPRL was irreversible, indicating the possible involvement of Gs protein in the prolactin action. From these results, we conclude that cAMP may be a second messenger in the dispersion of pigment induced by prolactin and that a novel protein receptor coupled with a Gs protein may be present in the membrane of erythrophores and xanthophores of teleost fish.
Intrinsic and Extrinsic Pathomechanisms in Vitiligo
Authors: TAÏEB ALAIN
Published: December 2004

Vitiligo is the most commonly acquired hypomelanosis, and is restricted to a limited cutaneous territory (focal/segmental vitiligo [SV]) or generalized in symmetric patches (nonsegmental vitiligo [NSV]). In the majority of cases, vitiligo corresponds to a loss of melanocytes, first in the epidermal compartment, and later in the follicular reservoir where most melanocytic stem cells are probably situated. There are many data currently supporting an impaired redox status of the epidermal melanin unit as a primary defect leading to inappropriate immune responses in NSV. SV is probably a mosaic developmental predisposition to melanocytic loss, with similar mechanisms at work on a limited scale, as suggested by its cutaneous distribution and success of autografting. In NSV, engraftment of autologous melanocytes is less durable, especially in areas prone to repeated trauma or pressure. Although melanocytes are the obvious target of the disease, keratinocytes, as providers of antioxidant molecules to melanocytes as well as cofactors in the synthesis of melanin, are probably involved. The production of autoantibodies and specific cytotoxic T cells is not surprising in the context of the massive uptake of melanocytic antigens by Langerhans cells in unstable vitiligo vulgaris, thereby allowing the self‐perpetuation of lesions. This article reviews the recent data on the pathophysiology of vitiligo, on the basis of clinical classification and the intrinsic/extrinsic nature of proposed pathomechanisms. Unfortunately, basic issues like pathological staging, clinical scoring, and eliciting factors have not yet been fully resolved. More genetic studies in vitiligo‐prone families and in specific genetic disorders associated with vitiligo are also needed.
Nicotine‐Induced Inflammatory Decreasing Effect on Passive Skin Arthus Reaction in Paraventricular Nucleus‐Lesioned Wistar Rats
Authors: Kubo Kaoru , Kita Taizo , Narushima Itaru , Tanaka Takeshi , Nakatani Toshiaki , Nakashima Toshikatsu
Published: December 2004

Abstract: To evaluate the relationship between nicotine and immunological inflammation, we investigated the effects of nicotine on plasma extravasation of the passive skin Arthus reaction, elicitated 4 hr after sensitizing skin with antiserum, and serum corticosterone levels in rats. Pretreatment with a single subcutaneous injection of nicotine (0.4 or 0.8 mg/kg) 30 or 60 min. before antigen challenge attenuated the passive skin Arthus reaction immunological inflammation. Serum corticosterone levels were dose‐dependently increased 30 and 60 min. after nicotine administration. Both markers co‐varied with a similar dose‐response and time course after the nicotine‐treatment. In addition, we also examined these nicotine‐induced responses after bilateral lesions of the hypothalamic paraventricular nucleus; both the nicotine‐induced suppression of immunological inflammation and the increased serum corticosterone levels were attenuated in bilateral paraventricular nucleus‐lesioned animals. Moreover, the immunological inflammatory decreasing effects of a single subcutaneous injection of nicotine (0.4 mg/kg) were antagonized by intraperitoneal preinjection with mecamylamine (1.0 mg/kg; blocking the brain nicotinic acetylcholine receptors) as well as by subcutaneous preinjection with mifepristone (30 mg/kg; a glucocorticoid receptor antagonist) but not by intraperitoneal preinjection with hexamethonium (2.0 mg/kg; a peripheral nicotinic acetylcholine receptors antagonist). Finally, intraperitoneal preinjection with cycloheximide (2 mg/kg), a protein synthesis inhibitor, abolished both the inhibitory effect of nicotine (0.4 mg/kg) on the dye leakage and the elevation of blood corticosterone levels. These findings indicate that the nicotine‐induced decreasing effect on immunological inflammatory response may be related to serum corticosterone levels elevated by an activation of the paraventricular nucleus through the brain nicotinic acetylcholine receptors.
Pharmacokinetics and Antidiuretic Effect of High‐Dose Desmopressin in Patients with Chronic Renal Failure
Authors: Ruzicka Hana , Björkman Sven , Lethagen Stefan , Sterner Gunnar
Published: December 2004

Abstract: High‐dose desmopressin shortens the bleeding time in uraemia. The aim of this study was to investigate the pharmacokinetics and the antidiuretic effect of desmopressin when given in a dose normally used for haemostasis to patients with reduced renal function. Ten patients with chronic renal failure of varying aetiology were enrolled in the study. The age was 58 (20–76) years (median and range), serum creatinine 447 (309–691) μmol/l and plasma clearance of iohexol 16 (8–19) ml/min./1.73 m2 body surface. After baseline measurements, desmopressin was infused at a dose of 0.3 μg/kg. The plasma concentration of desmopressin was followed for 26 hr during and after the infusion and the pharmacokinetic parameters were estimated by compartmental analysis. Urine volume and osmolality, as well as body weight, blood pressure, heart rate, haematocrit, serum osmolality, electrolytes and creatinine, were measured repeatedly during the day before and for two days after the infusion. The total clearance of desmopressin was 0.35 (0.21–0.47) ml/min./kg, the volume of distribution at steady state was 0.30 (0.17–0.38) l/kg and the terminal half‐life 9.7 (8.4–16) hr. After administration of desmopressin, urine osmolality increased significantly, by approximately 10%, and this increase lasted for 48 hr. Concomitantly, there was a modest but significant decrease in haematocrit. Thus, the clearance of desmopressin was on average decreased to approximately one quarter, and the terminal half‐life was prolonged 2–3 times in the patients as compared to previously published values for healthy adults. The single haemostatic dose of desmopressin given to patients with severe renal failure did not cause fluid overload or changes in serum electrolytes.
Blunted Central Bromocriptine‐Induced Tachycardia in Conscious, Malnourished Rats
Authors: Lahlou Saad , Lima Paula F. Araújo , Interaminense Leylliane F. L. , Duarte Gloria Pinto
Published: December 2004

Abstract: Bromocriptine‐induced tachycardia, persisting after adrenalectomy, is mediated by central dopamine D2 receptor stimulation through activation of the sympathetic outflow to the heart. The present study investigated the effects of malnutrition during pregnancy on bromocriptine‐induced tachycardia in adult conscious rats. Malnourished rats were obtained by feeding dams a multideficient diet (providing 8% protein) during mating and pregnancy. Birth weight was significantly reduced in malnourished rats when compared to control rats born to dams fed standard commercially diet (23% protein) during mating and pregnancy. Baseline mean aortic pressure and heart rate in malnourished rats were comparable to those of well‐nourished rats. Tachycardia (33±9 beats/min.), but not the hypotensive response to intravenous bromocriptine (150 μg/kg) was significantly reduced in malnourished rats, compared with control rats (70±10 beats/min.). In malnourished rats, pretreatment with intravenous domperidone (500 μg/kg) blocked the bromocriptine‐induced hypotension, without affecting the tachycardia. Neither cardiac vagal (40±6 beats/min.) nor sympathetic tone (76±6 beats/min.) was significantly altered by multideficient diet‐induced malnutrition (51±6 and 67±10 beats/min., respectively). In isolated perfused heart preparations from malnourished rats, positive inotropic response to isoproterenol (10−8 to 10−4 M) was not significantly different compared to that in control rats. In summary, malnutrition during foetal life blunted the bromocriptine‐induced tachycardia, an effect that could be related to central dopamine D2 receptor desensitization rather than to impairment of autonomic regulation of the heart or cardiac β‐adrenoceptor desensitization.
The Enteric Nervous System III: A Target for Pharmacological Treatment
Authors: Hansen Mark Berner
Published: December 2004

Abstract:The past decade has seen major advances in the pharmacological understanding of the nervous system of the gastrointestinal tract, the enteric nervous system, and its importance for gut functions in several states of disease. Indeed, the enteric nervous system has become a promising target in the treatment of many gastrointestinal symptoms and disorders. Some of these new therapeutic concepts, such as botulinum toxin for achalasia and serotonergic drugs for functional bowel diseases, are already in clinical use. This paper is part 3 of three Minireviews inPharmacology & Toxicology, and presents the neurogastrointestinal pharmacological therapeutic options in gastrointestinal pain, functional gastrointestinal disorders, inflammatory bowel diseases, cancer and related conditions with focus on future drug targets. The diagnosis of gastrointestinal neuropathy, the role of serotonin and related neuroendocrine transmitters, serotonergic drugs, and neurotrophic factors in neurogastrointestinal pharmacology will be addressed in this context.
RS‐4252 Inhibits Amyloid β‐Induced Cytotoxicity in HeLa Cells
Authors: Nishimura Satoko , Murasugi Takako , Kubo Takekazu , Kaneko Isao , Meguro Masaki , Marumoto Shinji , Kogen Hiroshi , Koyama Kazuo , Oda Tomiichiro , Nakagami Yasuhiro
Published: December 2004

Abstract: Progressive deposition of amyloid β peptide in the senile plaques is a principal event in the neurodegenerative process of Alzheimer's disease. Several reports have demonstrated that amyloid β is cytotoxic using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) as an indicator of viability in cells. With the MTT assay, we screened an in‐house library to find compounds which suppress amyloid β‐induced inhibition of MTT reduction. We have previously reported that 6‐ethyl‐N,N'‐bis(3‐hydroxyphenyl)[1,3,5]triazine‐2,4‐diamine (named RS‐0466), found in an in‐house library, was capable of significantly inhibiting amyloid β‐induced cytotoxicity in HeLa cells. From further screening hits, we newly focused on 4‐(7‐hydroxy‐2,2,4‐trimethyl‐chroman‐4‐yl)benzene‐1,3‐diol (named RS‐4252), which show comparable potency to RS‐0466 to ameliorate amyloid β‐induced cytotoxicity. Furthermore, RS‐4252 reversed the decrease in phosphorylated Akt by amyloid β. These results imply that RS‐4252 or one of its derivatives has the potential to be a therapeutic for Alzheimer's disease patients, and that activation of Akt is at least in part involved in the effect.
Influence of α‐Adrenoceptor Agonists and Antagonists on Imipramine‐Induced Hypothermia in Mice
Authors: Zarrindast Mohammad‐Reza , Sadeghi Sheyda , Sahebgharani Mousa
Published: December 2004

Abstract: Effects of adrenoceptor agonists and antagonists on imipramine‐induced hypothermia in mice were studied. Intraperitoneal injection of imipramine (10–40 mg kg−1), α2‐adrenoceptor agonist clonidine (0.05–0.1 mg kg−1), α1‐adrenoceptor agonist phenylephrine (6 mg kg−1) and α1‐adrenoceptor antagonist prazosin (1–4 mg kg−1) but not α2‐adrenoceptor antagonist yohimbine (1–4 mg kg−1) induced significant hypothermia. The hypothermic response induced by imipramine (10–30 mg kg−1) was not altered by clonidine (0.05–0.1 mg kg−1) or phenylephrine (2–6 mg kg−1). The response of imipramine (10–30 mg kg−1) was reduced significantly by yohimbine (2 mg kg−1) and was potentiated by prazosin (1 mg kg−1). The hypothermic effect of clonidine (0.1 mg kg−1) and imipramine (20 mg kg−1) were also decreased significantly by different doses of yohimbine (1–4 mg kg−1). The hypothermia induced by different doses of prazosin (1–4 mg kg−1) was not altered by yohimbine (2 mg kg−1) or by low dose of imipramine (10 mg kg−1). It is concluded that α2‐adrenoceptor mechanism may be involved in the hypothermic effect of imipramine.
016 Daily non‐solar UV exposure
Authors: Sayre R.M. , Dowdy J.C.
Published: December 2004

An examination of the UV emission by fluorescent and tungsten lamps often used for lighting in the home, office or school indicates a considerable amount of UV radiation load for unsuspecting individuals. The amount of UV exposure from non‐solar sources would appear to be potentially as great as 1/2–2/3 MEDs daily or 150 MED yearly. This is interesting as it exceeds the generally often‐quoted levels of expected UV accumulated from sunlight exposure during normal daily activities.

Of possibly greater significance is the fact that this exposure contains wavelengths not present in sunlight reaching the earth's surface. Fluorescent lamps, activated by excited mercury wavelengths, emit significant amounts of short radiation < 290 nm, including clearly detectable 254 nm lines. Similarly, the common tungsten bulbs, even low 60 Watt bulbs, emit detectable UV radiation as short as 280 nm. Wavelengths this short do not represent a detectable risk from outdoor exposure.

It would appear plausible that concern about the increasing risk of melanoma due to UV in sunlight exposure may be misplaced. Individuals at greatest risk include doctors, nurses, school teachers, lawyers and office workers and not farmers, fishermen, or construction workers. The indoor office workers would receive vastly greater exposure from artificial lighting, especially at non‐solar wavelengths, than would similar outdoor workers.
Description of the use of a risk estimation model to assess the increased risk of non‐melanoma skin cancer among outdoor workers in Central Queensland, Australia
Authors: Vishvakarman D. , Wong J. C. F.
Published: December 2004

Background: The aim was to use the measured data on annual exposure to ultraviolet (UV) radiation in the risk estimation model to estimate the increase in risk of Non‐Melanomic Skin Cancer (NMSC) among outdoor workers compared to indoor workers in Rockhampton (lat. 23°S), Central Queensland, Australia.

Methods: Results on annual occupational exposure measured on two occupational groups namely Australia Post Mail Delivery Personnel (APMDP) and Physical Education Teachers (PE) using film badge dosimeters was used in the risk estimation model to determine the increase in risk of NMSC with years of outdoor occupational exposure compared to indoor workers. The sensitivity of the model was tested for variations in recreational and childhood exposure of both groups, as well as occupational exposure of indoor workers.

Results: For APMDP the increase in risk for Basal cell carcinoma (BCC) varied from 1.1 to 3.6 for 5–20 years of exposure and for Squamous cell carcinoma (SCC) the risk varied from 1.2 to 5.5 for the same periods of exposure. For the PE teachers the risk for BCC varied from 1.1 to 1.8 and for SCC the range was 1.1–2.3 for similar exposure periods.

Conclusion: The increased risk estimates did not show any significant changes for variations in occupational and recreational exposure. A maximum change of 20% was computed for 25% variation in childhood exposure, which was mainly for the APMDP with high occupational exposure levels and more than 10 years of occupational exposure. The increased risk estimates are useful to identify high risk groups at an early age and implement long‐term protective measures against NMSC.
Topical 5‐aminolaevulinic acid photodynamic therapy for cutaneous lesions: outcome and comparison of light sources
Authors: Clark C. , Bryden A. , Dawe R. , Moseley H. , Ferguson J. , Ibbotson S. H.
Published: December 2004

Background: Topical 5‐aminolaevulinic acid (ALA) photodynamic therapy (PDT) is increasingly used for superficial non‐melanoma skin cancers and their precursors.

Methods: We report our 3‐year experience of topical ALA‐PDT, with a preliminary comparison of the effects of broadband and laser light sources.

Results: We performed 688 treatments on 483 lesions in 207 patients. Complete clearance was achieved in 222/239 lesions of Bowen's disease (BD), superfi‐cial basal cell carcinoma (sBCC) and actinic keratosis (AK) (93%) – 117/129 BD (91%), 84/87 sBCC (97%) and 21/23 AK (91%), with a median follow up of 48 weeks. Broadband and laser light sources were of similar efficacy. Recurrences have occurred in 10.3% BD, 4.8% sBCC and 4.8% AK. Adverse effects from PDT were uncommon but included pig‐mentary change (2%) and minor scarring (2%). How‐ever, severe pain was experienced in 16–21% of treatments using the high‐output broadband and laser sources, but in only 2% with the low‐output xenon arc source.

Conclusion: Topical ALA‐PDT is effective for BD, sBCC and AK and has been an invaluable addition to our dermatology service. Efficacy is similar for broadband and laser light sources, although treatment at higher surface irradiance may be painful, and excellent cosmetic results can be achieved.
Photosensitive erythema multiforme and erythema multiforme‐like polymorphous light eruption
Authors: Calzavara Pinton PG. , Venturini M. , Capezzera R. , Zane C. , Facchetti F.
Published: December 2004

Background: Photosensitive erythema multiforme (EM) is a rare disorder. It usually occurs only if a herpes virus infection or ingestion of drugs precedes exposure to sunlight in selected patients.

Methods: We report a 37‐year‐old man who had recurrent EM eruptions following sun exposures over a period of 20 years. Lesions were prevalently located on exposed skin, but unexposed skin and mucosa of the oropharynx were also affected. The patient had poor tolerance to sunlight and denied having herpes simplex infection or using drugs.

Results: Provocative phototest induced clinically and histologically similar lesions at low dose thresholds of UVA (10 J/cm2) and UVB (100 mJ/cm2).

Conclusion: On the basis of clinical and histological findings and results of phototesting, a diagnosis of photosensitive EM was made. The EM‐like variant of polymorphous light eruption is discussed in the differential diagnosis.
A study of differences in surface roughness between sun‐exposed and unexposed skin with age
Authors: Edwards C. , Heggie R. , Marks R.
Published: December 2004

Background: To understand and separate the roles of age and solar ultraviolet exposure (sun damage) on the surface roughness of skin.

Objectives: To determine the effects of age and site (sun exposed vs. unexposed) on skin roughness in normal healthy subjects.

Subjects/Methods: Using a stylus profilometer and silicone skin surface replicas, we have measured skin surface roughness parameters on habitually exposed (back of hand) and habitually unexposed (upper buttock) skin sites from the same individual in a sample of 73 subjects from the normal population. We compared the two sites in order to determine any differences in roughness caused, we postulate, by the effect of solar ultraviolet exposure on the exposed site.

Results: We found that the two sites are indistinguishable in roughness until after 30 years of age. For the over 30 years group, the difference between exposed and unexposed skin roughness correlated strongly with age. For all ages, skin roughness showed a positive correlation with age on the unexposed, but not the exposed, site. On the hand site subjects aged 40 years and older had significantly smoother skin than those aged less than 40 years, as measured by one roughness parameter. On the back, the older group had significantly rougher skin than the younger group measured by two roughness parameters.

Conclusions: We propose that on the back of the hands, solar damage reverses or reduces the increase in roughness which would otherwise be caused by intrinsic ageing.
Chloroplast movements in the field
Authors: WILLIAMS W. E. , GORTON H. L. , WITIAK S. M.
Published: December 2004

An ecophysiological understanding of chloroplast movements in leaves requires measurement of these movements under field conditions. A field‐portable instrument was constructed, based on a pulsed measuring beam and lock‐in detection that measures chloroplast movements in attached leaves by sensing the resultant changes in leaf transmittance. In the instrument and generally in nature, leaves are illuminated obliquely, in contrast with the perpendicular illumination used in most laboratory experiments on chloroplast movement. Microscopic analysis of cells illuminated obliquely with bright light verified that chloroplasts move out of the light path, and transmittance changes in response to oblique light were robust. Chloroplast movements in Alocasia brisbanensis under natural sunlight express kinetics and light requirements expected from laboratory observations: chloroplasts were in the periclinal position at dawn and dusk, anticlinal position in full sunlight midday, and in an intermediate position at night. Movement in response to bright light was rapid allowing responses to brief sunflecks. Movements in Helianthus tuberosum, Eustrephus latifolius and Cissus hypoglauca were qualitatively similar with differing kinetics and magnitude. In all four species, chloroplasts were in motion most of the time, rarely achieving the extreme anticlinal or periclinal positions.
Graminicide resistance in a blackgrass (Alopecurus myosuroides) population correlates with insensitivity of acetyl‐CoA carboxylase
Authors: PRICE L. J. , MOSS S. R. , COLE D. J. , HARWOOD J. L.
Published: December 2004

The appearance of biotypes of the annual grass weed black‐grass (Alopecurus myosuroides L. Huds), which are resistant to certain graminicides, is the most significant example of acquired resistance to herbicides seen so far in European agriculture. An investigation was perfomed into the basis of the specific cross‐resistance to cyclohexanedione (CHD) and aryloxyphenoxypropionoic acid (AOPP) herbicides in the ‘Notts A1’ population of A. myosuroides, which survived treatment of fields with recommended rates of AOPP herbicides. In comparison with the wild‐type ‘Rothamsted’ population, the resistant biotype showed over 100‐fold resistance to these herbicides in a hydroponic growth system. Biosynthesis of fatty acids and activity of crude extracts of acetyl‐CoA carboxylase (ACCase) were commensurately less sensitive to these herbicides in Notts A1 compared with the Rothamsted biotype. These data are consistent with the hypothesis that the highly resistant population has arisen through selection of a mutant ACCase which is much less sensitive to the AOPP and CHD graminicides. Rapidly growing cell suspension cultures established from the Notts A1 population also showed high resistance indices for CHD or AOPP herbicides compared with cultures from the Rothamsted biotype. Fatty acid biosynthesis and ACCase activity in the cell suspensions were similarly sensitive towards the graminicides to those in the foliar tissue counterparts of the resistant and sensitive populations. Moreover, purification of the main (chloroplast) isoform of acetyl‐CoA carboxylase showed that this enzyme from the Notts A1 population was over 200‐fold less sensitive towards the AOPP herbicide, quizalofop, than the equivalent isoform from the Rothamsted population. These data again fully supported the proposal that resistance in the Notts biotype is due to an insensitive acetyl‐CoA carboxylase isoform. Overall, cell suspensions were also demonstrated to be excellent tools for further investigation of the molecular basis of the high level herbicide resistance which is prone to occur in A. myosuroides.
Overexpression of bacterial catalase in tomato leaf chloroplasts enhances photo‐oxidative stress tolerance
Authors: MOHAMED E.‐A. , IWAKI T. , MUNIR I. , TAMOI M. , SHIGEOKA S. , WADANO A.
Published: December 2004

The Escherichia coli gene katE, which is driven by the promoter of the Rubisco small subunit gene of tomato, rbcS3C, was introduced into a tomato (Lycopersicon esculentum Mill.) by Agrobacterium tumefaciens‐mediated transformation. Catalase activity in progeny from transgenic plants was approximately three‐fold higher than that in wild‐type plants. Leaf discs from transgenic plants remained green at 24 h after treatment with 1 µm paraquat under moderate light intensity, whereas leaf discs from wild‐type plants showed severe bleaching after the same treatment. Moreover, ion leakage from transgenic leaf discs was significantly less than that from wild‐type leaf discs at 24 h after treatment with 1 µm paraquat and 10 mm H2O2, respectively, under moderate light intensity. To evaluate the efficiency of the E. coli catalase to protect the whole transgenic plant from the oxidative stress, transgenic and wild‐type plants were sprayed with 100 µm paraquat and exposed to high light illumination (800 µmol m−2 s−1). After 24 h, the leaves of the transgenic plants were less damaged than the leaves of the wild‐type plants. The catalase activity and the photosynthesis activity (indicated by the Fv/Fm ratio) were less affected by paraquat treatment in leaves of transgenic plants, whereas the activities of the chloroplastic ascorbate peroxidase isoenzymes and the ascorbate content decreased in both lines. In addition, the transgenic plants showed increased tolerance to the oxidative damage (decrease of the CO2 fixation and photosystem II activity and increase of the lipid peroxidation) caused by drought stress or chilling stress (4 °C) under high light intensity (1000 µmol m−2 s−1). These results indicate that the expression of the catalase in chloroplasts has a positive effect on the protection of the transgenic plants from the photo‐oxidative stress invoked by paraquat treatment, drought stress and chilling stress.
The plastidic Arabidopsis protoporphyrinogen IX oxidase gene, with or without the transit sequence, confers resistance to the diphenyl ether herbicide in rice
Authors: HA S. B. , LEE S. B. , LEE Y. , YANG K. , LEE N. , JANG S. M. , CHUNG J. S. , JUNG S. , KIM Y. S. , WI S. G. , BACK K.
Published: December 2004

Agrobacterium‐mediated gene transformation was used to introduce plastidic protoporphyrinogen IX oxidase (Protox) genes from Arabidopsis, with and without the transit sequence, into the rice genome. They were placed under the control of the constitutive and ubiquitous maize ubiquitin promoter, and their abilities to confer resistance to the diphenyl ether‐type herbicide, oxyfluorfen were compared. The integration and expression of the transgene in the T1 generation was examined by Southern, northern and western blot analyses. Surprisingly, as judged by an in vivo seed germination assay and an in vitro cellular leakage assay, both lines were similarly resistant to oxyfluorfen. The tolerance to cellular damage (lipid peroxidation and electrolyte leakage) was higher in transgenic plants than in wild‐type plants. In transgenic plants, the degree of herbicide resistance varied directly with the absolute amount of Protox protein expression. Both the intact protein and the protein with the transit sequence deleted were accumulated in plastids.
Studying guard cells in the intact plant: modulation of stomatal movement by apoplastic factors
Authors: Roelfsema M. Rob G. , Hedrich Rainer
Published: December 2004

Here, we discuss why guard cells in intact plants respond to environmental signals in a different way than guard cells in epidermal strips, or protoplasts thereof. In intact leaves stomatal opening is counteracted by epidermal cells that press against the guard cells. Changes in the turgor of epidermal cells therefore can alter the stomatal aperture. In addition, stomatal opening may be modulated by the solute composition of the guard cell wall. Changes in apoplastic K+, Cl− and Ca2+ occur after light–dark transitions, but not in such a way that it would support stomatal opening. Organic anions may play a role, since they enhance the open probability of anion channels in the plasma membrane. Furthermore, studies with auxin‐resistant and abscisic acid‐insensitive mutants show that light‐induced stomatal opening is modulated by these hormones. Using the newly developed method in which guard cells in the intact plant are impaled with double‐barreled electrodes, the role of these apoplastic factors now can be studied on single guard cells that are still in their natural environment.
The guard cell chloroplast: a perspective for the twenty‐first century
Authors: Zeiger Eduardo , Talbott Lawrence D. , Frechilla Silvia , Srivastava Alaka , Zhu Jianxin
Published: December 2004

The guard cell chloroplast is the site of perception of blue light and of photosynthetically active radiation, and of at least one of the mechanisms sensing CO2 in the guard cell. The guard cell chloroplast has been the focus of intense controversy over its capacity for light sensing and photosynthetic carbon fixation, and the osmoregulatory mechanisms mediating stomatal movements. It is argued here that a primary reason behind these long‐lived controversies is the remarkable plasticity of the guard cell, which has resulted in responses being generalized as basic properties when opposite responses appear to be the norm under different environmental or experimental conditions. Examples of guard cell plasticity are described, including variation of chlorophyll fluorescence transients over a daily course, acclimation of the guard cell responses to blue light and CO2, the shift from potassium to sucrose in daily courses of osmoregulation and the transduction of red light into different osmoregulatory pathways. Recent findings on the properties of the guard cell chloroplast are also presented, including the role of the chloroplastic carotenoid, zeaxanthin, in blue light photoreception, the blue‐green reversibility of stomatal movements, and the involvement of phytochrome in the stomatal response to light in the orchid, Paphiopedilum.
Kaiser filter for antialiasing in digital photogrammetry
Authors: Khoshelham Kourosh , Azizi Ali
Published: December 2004

Image aliasing is a problem appearing as artefacts in digitally resampled images, which degrades the quality of the image. In digital rectification and texture mapping, pixels from an input image are transformed to pixels of an output image. The discrete nature of a digital image causes aliasing in the transformed image. In this paper the source of aliasing and the theory of antialiasing are described. The necessity of a precise filter design in antialiasing is discussed and a filter based on a Kaiser adjustable window is designed. Different practical antialiasing methods are described as well as interpolation methods, which are conventional in photogrammetry. Selected antialiasing methods are implemented and applied to a close range image. An objective analysis is carried out by applying inverse transformations to rectified images and deriving some measures to estimate the information loss for each method by comparing original and reconstructed images. Results indicate that interpolation methods are not capable of removing or reducing aliasing in highly decimating transformations. The output images of interpolation methods therefore suffer from edge corruption and interfusion of small features. Applying a Kaiser filter with a precise antialiasing method results in the least information loss and considerably reduces aliasing at the expense of higher computation load.
Mathematical modelling of historical reconnaissance CORONA KH‐4B Imagery
Authors: Sohn Hong‐Gyoo , Kim Gi‐Hong , Yom Jae‐Hong
Published: December 2004

This paper describes three mathematical modelling methods for high‐resolution declassified CORONA KH‐4B images. Since CORONA images are collected with a panoramic camera, several types of geometric distortions are involved. Two methods use the modified collinearity equations, and the third involves the terrain‐dependent rational function model (RFM) which is considered to be a generic sensor model. Comparative analysis of the three mathematical modelling methods is undertaken. The results show that a ± 1·5 pixels level of horizontal and vertical accuracy can be obtained. A digital elevation model (DEM) of a test site is also created.