bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maintaining Cell Sensitivity to G‐Protein Coupled Receptor Agonists: Neurotensin and the Role of Receptor Gene Activation
Authors: Souazé F. 
Published: March 2003

AbstractIn the last few years, a number of studies have brought new insights into the fundamental mechanisms of cell desensitization and internalization of G‐protein coupled receptors. Such studies have demonstrated that cells remain desensitized from a few minutes to several hours, after exposure to high concentrations of agonist. However, in vivo, agonists such as hormones are always present, even in small amounts, and such long desensitization is not conceivable, since constant stimulation of cells is required for physiological responses. Under such circumstances, cells would require a means to permanently maintain sensitivity to various internal or external stimuli. In the present review, we have taken as an example the expression of the high affinity neurotensin receptor, a seven transmembrane G‐protein coupled receptor, upon prolonged exposure to its agonist, and observed that cells remained sensitive only if the receptor gene was activated by the agonist. Consequently, new receptors were synthesized, and either delivered to the cell surface or accumulated in submembrane pools. This regulation takes place only after prolonged and intense agonist stimulation. Under these conditions, it is proposed that receptor turnover is accelerated in proportion to the agonist concentration in order to allow the cells to produce an adapted cellular response to external stimuli. Such mechanisms thus play a key role in cell sensitivity to hormones.
The Role of Leptin in the Regulation of Energy Balance and Adiposity
Authors: Van Dijk Gertjan 
Published: March 2003

AbstractSince its discovery, leptin (a 167‐amino acid product of the OB gene) has quickly moved to the forefront as an important hormone for regulation of energy balance. It closes a feedback loop from adipose tissue to hypothalamic neuropeptide‐containing neural circuitry involved in regulation of food intake and neuroendocrine/autonomic outflow. While increased central leptin signalling reduces adiposity via a reduction in food intake, it also has remarkable metabolic effects that promote leanness, independent of food intake. These include: (i) increased energy expenditure, (ii) in‐place degradation of fat, and (iii) increased thermogenesis. Hypothalamic neurones that synthesize corticotropin releasing hormone and melanocortins (i.e. α‐melanocyte‐stimulating hormone and agouti‐related protein) are likely effector pathways that mediate the anorexigenic and metabolic effects of leptin. Activation of sympathetic outflow (via neuropeptidergic effector pathways of central leptin) to a number of tissues that store fat might be an important mechanism through which these peripheral metabolic effects are elicited. It is proposed that these peripheral metabolic effects contribute to the satiating properties of leptin.
The Melanocortin Agonist Melanotan‐II Reduces the Orexigenic and Adipogenic Effects of Neuropeptide Y (NPY) but Does not Affect the NPY‐Driven Suppressive Effects on the Gonadotropic and Somatotropic Axes in the Male Rat
Authors: Raposinho P. D. , White R. B. , Aubert M. L. 
Published: March 2003

AbstractNeuropeptide Y (NPY) is a strong orexigenic neurotransmitter also known to modulate several neuroendocrine axes. α‐Melanocyte‐stimulating hormone (MSH) is an essential anorectic neuropeptide, acting on hypothalamic MC3/4 receptor subtypes. When given as an intracerebroventricular bolus injection, Melanotan‐II (MT‐II), a non selective MC receptor agonist, inhibits feeding, suppresses the NPY orexigenic action, and reduces basal insulinaemia. We evaluated the effects of a 7‐day central infusion of MT‐II (15 nmol/day) given either alone or in association with NPY (5 nmol/day) in male Sprague‐Dawley rats. MT‐II produced almost full anorexia for 1–2 days but then feeding gradually returned to normal despite continued MT‐II infusion. When coinfused with NPY, MT‐II also produced the same initial anorectic episode but then maintained feeding to upper normal levels, thus cancelling the hyperphagia driven by NPY. Whereas NPY infusion produced a doubling of fat pad weight, MT‐II reduced adiposity by a factor of two compared to pair‐fed rats, and vastly curtailed the NPY‐driven increase in fat pad weight. MT‐II infusion also significantly curtailed the NPY‐induced rise in insulin and leptin secretions. NPY infusion significantly inhibited hypothalamic pro‐opiomelanocortin mRNA expression, most likely cancelling the α‐MSH anorectic activity. As expected from previous studies, chronic NPY infusion strongly inhibited both the gonadotropic and somatotropic axes, and coinfusion of MT‐II did not reverse these NPY‐driven effects, in sharp contrast with that seen for the metabolic data. MT‐II infusion alone had little effect on these axes. In conclusion, chronic MT‐II infusion generated a severe but transient reduction in feeding, suggesting an escape phenomenon, and clearly reduced fat pad size. When coinfused with NPY, MT‐II was able to cancel most of the NPY effects on feeding, but not those on the neuroendocrine axes. It appears therefore that, as expected, NPY and α‐MSH closely interact in the control of feeding, whereas the neural pathways by which NPY affects growth and reproduction are distinct and not sensitive to MC peptide modulation.
A Gonadotropin‐Releasing Hormone Insensitive, Thapsigargin‐Sensitive Ca2+ Store Reduces Basal Gonadotropin Exocytosis and Gene Expression: Comparison with Agonist‐Sensitive Ca2+ Stores
Authors: Johnson J. D. , Klausen C. , Habibi H. , Chang J. P. 
Published: March 2003

AbstractWe examined whether distinct Ca2+ stores differentially control basal and gonadotropin (GTH‐II)‐releasing hormone (GnRH)‐evoked GTH‐II release, long‐term GTH‐II secretion and contents, and GTH‐II‐β mRNA expression in goldfish. Thapsigargin (Tg)‐sensitive Ca2+ stores mediated neither caffeine‐evoked GTH‐II release, nor salmon (s)GnRH‐ and chicken (c)GnRH‐II‐stimulated secretion; the latter responses were previously shown to involve ryanodine (Ry)‐sensitive Ca2+ stores. Surprisingly, Tg decreased basal GTH‐II release. This response was attenuated by prior exposure to sGnRH and caffeine, but was insensitive to the phosphatase inhibitor okadaic acid, the inhibitor of constitutive release brefeldin A and cGnRH‐II. GTH‐II‐β mRNA expression was decreased at 24 h by 2 µm Tg, and by inhibiting (10 µm Ry) and stimulating (1 nm Ry) Ry receptors. Transient increases in GTH‐II‐β mRNA were observed at 2 h and 12 h following 10 µm and 1 nm Ry treatment, respectively. Effects of Tg, Ry and GnRH on long‐term GTH‐II secretion, contents and apparent production differed from one another, and these changes were not well correlated with changes in GTH‐II‐β mRNA expression. Our data show that GTH‐II secretion, storage and transcription can be independently controlled by distinct Ca2+ stores.
Oestradiol‐Dependent and ‐Independent Modulation of Tyrosine Hydroxylase mRNA Levels in Subpopulations of A1 and A2 Neurones with Oestrogen Receptor (ER)α and ERβ Gene Expression
Authors: Curran‐Rauhut M. A. , Petersen S. L. 
Published: March 2003

AbstractOestradiol (E2) induces luteinizing hormone‐releasing hormone (LHRH) hypersecretion, thereby triggering LH surge release in ovariectomized (OVX) rats. Neural signals responsible for the surge are marked by a morning increase in LHRH gene expression and an afternoon increase in LHRH release. Evidence suggests that subpopulations of noradrenergic neurones may be responsible for one or both of these signals. To further investigate this issue, we examined effects of E2on the activity of A1 and A2 noradrenergic neurones, as reflected in changes in tyrosine hydroxylase (TH) mRNA expression, on the day of LH surge release. We then used dual‐labelin situhybridization to determine whether E2‐induced changes occurred primarily in A1 and A2 subdivisions wherein most noradrenergic neurones expressed oestrogen receptor (ER)α and/or ERβ mRNA. We found that in all subdivisions, levels of TH mRNA were higher in E2‐ than oil‐treated rats at 12.00 h. These differences resulted from a decline in TH mRNA expression in oil‐treated rats, as well as a rise in levels in E2‐treated rats between 10.00 h and 12.00 h. During the afternoon, TH mRNA expression in most A1 and A2 subdivisions peaked at 14.00 h when LH surge release began. However, in all but the middle and caudal A2 subdivisons, levels were similar in E2‐treated and control rats at this time. This was attributable to a widespread increase in TH mRNA expression between 12.00 h and 14.00 h in OVX rats. There was no evidence that E2induced changes in TH mRNA expression preferentially in regions wherein most neurones contained ERα or ERβ mRNA. Our findings suggest that E2activation of middle and caudal A2 neurones, in conjunction with the widespread E2‐independent activation of noradrenergic neurones in other subdivisions, may play a role in the induction of LH surge release.
Training, skills and caseloads of community mental health support workers involved in case management: evaluation from the initial UK demonstration sites
Authors: Davis Bryn , WARD M. F. , ARMSTRONG C. , LELLIOTT P. , DAVIES M. 
Published: March 2003

This paper describes phase one of a three phase, Department of Health funded project, led by the Mental Health Programme of the Royal College of Nursing Institute in collaboration with the Research Unit of the Royal College of Psychiatrists and the School of Social Work at the University of East Anglia. Its project aims were to establish whether the work of demonstration sites in mental health case management had developed beyond their original structure, to compare their current profile with the general literature on case management and assertive outreach and to use this data to reach consensus about issues affecting the work of those healthcare workers who currently see themselves working as case managers. Central to these aims were the experiences and narratives of the demonstration site case managers themselves.In 1995 data were collected from six fieldwork sites in England using semistructured interviews. Similarities and differences between the literature and the fieldwork data were used to inform a consensus conference. The main areas of investigation were organizational considerations, the nature of innovative projects and user involvement. The paper concludes that there are serious problems with the perceived role of case managers, their support and training and further difficulties attributed to interagency working. Finally, it is clear that the exact nature of the client group most suited to UK case management typology has not yet been resolved.
Carbachol microinjection into the caudal peribrachial area induces long‐term enhancement of PGO wave activity but not REM sleep
Authors: Quattrochi James J. , Hobson J. Allan 
Published: March 2003

SummaryThis study presents new findings of carbachol‐induced long‐term ponto‐geniculo‐occipital (PGO) enhancement lasting five days, but without REM sleep enhancement. A quantitative analysis of the number and types of bilateral PGO wave events during slow wave sleep with PGO activity (SP) and REM was performed in each of four cats over a period of six days following a single unilateral microinjection of carbachol nanospheres into the caudolateral peribrachial area. The results demonstrate increases in the summed total of all PGO wave events to continue for five days postcarbachol reaching a peak sixfold increase on day three in SP and REM. The tendency of PGO waves to occur in clusters of greater than three waves increased sevenfold on day three in SP and fourfold during REM. These findings indicate a dissociation of long‐term PGO enhancement from long‐term REM enhancement, and suggest that even a sixfold increase in PGO activity alone is not, in itself, sufficient to produce the cholinergic orchestration of REM sleep enhancement.
The effect of drugs commonly used in the treatment of equine articular disorders on the activity of equine matrix metalloproteinase‐2 and 9
Authors: Clegg  , Jones  , Carter  
Published: March 2003

Loss of articular cartilage, which is the most important pathological lesion occurring in osteoarthritis, has been shown to be enzymatically mediated. The matrix metalloproteinases (MMPs) are a group of enzymes which have been implicated in this degradation of articular cartilage matrix. The use of pharmacological agents to inhibit this catabolic process in the joint is a potential route for therapeutic intervention. The gelatinase MMPs, MMPs‐2 and 9, were purified by affinity chromatography from equine cell cultures. The ability of phenylbutazone, flunixin, betamethasone, dexamethasone, methylprednisolone acetate (MPA), hyaluronan, pentosan polysulphate and polysulphated glycosaminoglycan (PSGAG) to inhibit equine MMPs‐2 and 9 were assessed by two degradation assays. Whilst some agents did have direct effects on MMP activity, these effects were only obtained at concentrations which were unlikely to be achieved for any length of time in vivo. It is improbable that any pharmacological agent, currently used in the horse, has a significant effect on gelatinase MMP activity.
Bats of Lithuania: distribution, status and protection
Authors: Pauza D. H. , Pauziene And N. 
Published: March 2003

AbstractThe Lithuanian bat fauna includes 14 species. Myotis daubentoni, Pipistrellus nathusii, Plecotus auritus and Eptesicus serotinus are the most abundant and widespread species, although recently P. auritus has disappeared from some hibernacula. There are still abundant populations of Myotis nattereri, Myotis brandti and Barbastella barbastellus in hibernacula, while their status in summer is unknown. Myotis dasycneme is probably very rare and endangered. The status of Myotis mystacinus and Nyctalus leisleri is not clear, but they are most likely very rare because very few specimens have been found. So far little is known about status of Nyctalus noctula, Pipistrellus pipistrellus, Eptesicus nilssoni and Vespertilio murinus because these species are common only during autumn bat migration along the Baltic Sea coast. Two other species, Myotis bechsteini and Rhinolophus hipposideros, have been rejected from the list of bats of Lithuania, because old references to records of these species were not reliable.From what is currently known it seems that: (i) the northern limits of distribution of B. barbastellus and E. serotinus reach the middle of Lithuania between 55°N and 56°N, which may also be the southern limit of abundance of E. nilssoni; (ii) the wintering site with the largest numbers of bats in Lithuania is the vaults of Kaunas fortress, where every year eight species are found hibernating in numbers estimated as follows: M. daubentoni 400–500, M. nattereri 200–300, M. brandti 80–100, B.barbastellus 200–300, P. auritus 40–60, M. dasycneme 15–20 and a few E. serotinus and E. nilssoni.In Lithuania nine bat species have been protected by law since 1991, as species included in the Red Data Book. Also 11 bat reserves have been designated in Kaunas fortress to protect the most important hibernation sites in Lithuania.
Identifying mammalian predators from bite marks: a tool for focusing wildlife protection
Authors: Lyver P. O’B. 
Published: March 2003

ABSTRACTDead Sooty Shearwater, Puffinus griseus, chicks and adults were collected from seven colonies on South Island, New Zealand in the 1993–96 breeding seasons. An estimated 97% of 118 deaths were from predation. Thirty‐four definite predator bite pairs were identified on 27 carcasses. Twenty‐one (78%) of the carcasses had bite pairs with intercanine distances < 9.5 mm which suggests that Stoats (Mustela erminea) were the principal predators. One chick was killed by a feral House Cat (Felis catus), and it is likely that feral Ferrets (M. furo) were responsible for a proportion of the deaths. Nearly three quarters of definite Stoat bite pairs were identified in the head region. The analyses of bite marks offers cheap and statistically reliable identification of predators provided carcasses are collected fresh and flesh is removed to examine tooth punctures in bone.
Changes in the food of British Barn Owls (Tyto alba) between 1974 and 1997
Authors: Love R. Alasdair , Webon Charlotte , Glue David E. , Harris Stephen , Harris Stephen 
Published: March 2003

ABSTRACTComparison of the results of a 1993–97 Barn Owl Tyto alba pellet survey with those of a similar survey from 1956–74 showed that Barn Owl diet had changed significantly. The primary differences were a widespread decrease in the percentage of Common Shrew Sorex araneus, combined with an increase in Pygmy Shrew Sorex minutus. The percentage of Wood and Yellow‐necked mice Apodemus sylvaticus and A. flavicollis and Bank Vole Clethrionomys glareolus in the diet also increased. Changes in Barn Owl diet since 1974 were independent of land‐class group, but were dependent upon region. This was due primarily to a large increase in the percentage of Apodemus spp. in Eastern England. Whilst the percentage of Pygmy Shrew in Barn Owl diet showed significant regional variation, there was no significant variation between land‐class groups. The diversity of Barn Owl diet increased between 1974 and 1997, although it was still lower in 1997 than earlier in the century. This increase was dependent upon region, but independent of land‐class group. The combined results of both surveys showed significant interland‐class group variation in dietary diversity. Changes in diet are discussed in relation to the intensification of agriculture and other changes in land management since the 1970s. The effects on Barn Owls of these changes in prey abundance are discussed, particularly in relation to the decline in Barn Owl numbers during the twentieth century.
Habitat use, diet and roost selection by the Big Brown Bat (Eptesicus fuscus) in North America: a case for conserving an abundant species
Authors: AGOSTA SALVATORE J. 
Published: March 2003

ABSTRACTInsectivorous bats are integral components of terrestrial ecosystems. Despite this, a growing number of factors causing world‐wide declines in bat populations have been identified. Relatively abundant species are important for bat conservation because of their role in ecosystems and the research opportunities they offer. In addition, species that have been well‐studied present unique opportunities to synthesize information and highlight important areas of focus for conservation and research. This paper focuses on a well‐studied abundant bat,Eptesicus fuscus. I review the relevant literature on habitat use, diet and roost selection byE. fuscusin North America, and highlight important areas of conservation and research for this species, including the effects of roost disturbance, control of economically important insect pests, exposure to pesticides, long‐term monitoring of populations, and the potential consequences of expanding populations. These issues have broad implications for other species and can be used to focus future research and conservation efforts.
Effect of arena size on behaviour and mortality of the oriental cockroach Blatta orientalis in arenas with a cypermethrin deposit adjacent to harbourage access points
Authors: LE PATOUREL  
Published: March 2003

Activity and survival of adult female Blatta orientalis was investigated using tagged cockroaches in periodically illuminated arenas (LD 12:12 h) with a harbourage at one end. The arenas were rectangular with a width of 50 cm and lengths up to 480 cm. A cypermethrin‐treated plywood plate (50 × 11 cm) substrate across the harbourage access points caused cockroaches to be exposed to the insecticide deposit by tarsal contact as they entered or left the harbourage. The effects of varying arena length and cypermethrin concentration were tested at 28°C. The LC50 following 3 days exposure ranged from 5.7 to 11.8 mg/m2 on the plywood plate for arena lengths of 60 to 480 cm, respectively; cypermethrin at 30 mg/m2 produced 100% knockdown of B. orientalis within one 12 h dark period.During darkness, active cockroaches spent most time close to the harbourage or around food and water stations, at the far end of the arena, and made frequent returns into the harbourage. For arena length 120 cm, the mean duration of contact with treated plates during the first hour of the dark period was significantly less than contact time on untreated plates, but during 12 h the cumulative contact times were not significantly different between treated and untreated plates. During the first 4 h of the dark period, mean cockroach numbers on the treated plate declined as arena length increased, but not as rapidly as the mean number/unit area over the rest of the arena. The arena design is considered suitable for comparative testing of fast‐acting neuroactive insecticide deposits against cockroaches.
Comparative repellency of commercial formulations of deet, permethrin and citronellal against the mosquito Aedes aegypti, using a collagen membrane technique compared with human arm tests
Authors: COCKCROFT  , COSGROVE  , WOOD  
Published: March 2003

A collagen membrane technique, based on the membrane blood‐feeding system of Cosgrove et al. (1994) , was used to compare repellents against Aedes aegypti mosquitoes. Repellency was defined in terms of inhibition of probing (ED50 and ED90) after 5 min exposure. A direct comparison was made with repellency from probing after 5 min on five male volunteers.Four repellent products were compared with technical DEET as the standard. The liquid formulations tested were: Autan® (20% deet; Bayer); Repel Plus® (20% deet plus 0.05% permethrin; Boots); permethrin (Zeneca) and citronellal (Sigma) .Membrane and arm tests gave similar results. Deet formulations required less active compound than citronellal for the same degree of repellency. Pure deet and Autan gave similar results, dose for dose. Permethrin was highly repellent at very low doses, but Repel Plus did not enhance the immediate repellency of deet. A technique using the same membrane system was developed to evaluate persistence of Autan, which declined to 75% after 1 h against Ae. aegypti, and to about 50% after 2–4 h.
Dynamics of diapause recruitment in populations of the face fly, Musca autumnalis
Authors: Krafsur E. S. , Moon R. D. , Kim Y. , Rosales A. L. 
Published: March 2003

SummaryField populations of face flies, Musca autumnalis DeGeer (Diptera: Muscidae) were sampled serially in the late summers and autumns of 1985–96, in order to measure the dynamics of diapause development in Iowa, U.S.A. Fat body hypertrophy and ovarian development were assessed through dissection, and pteridine quantities in the fly heads were measured spectrofluorometrically to estimate their physiological and chronological ages. Published laboratory studies of diapause induction established the expectation that diapause incidence would vary over successive years with prevailing temperatures. The expectation was not met by field data. Patterns in the frequencies of hypertrophied fat body and of vitellogenic nullipars indicated that about 50% of recruited adults began developing into diapause in the second week of September in each year. Degree‐day summations for each year from 1985 to 1996 suggested that the hypothetical mean optimal time for switching into diapause would be in the second week of September, because a rapidly diminishing proportion of eggs laid later would result in viable, overwintering flies. It was concluded that face flies do not use daily temperatures in late summer, but instead cue on photoperiod for diapause.