bluuebunny/crossref_metadata_2025 huggingface dataset:
Sectoral Queuing in a Transitional Economy: The Case of Nicaragua in the 1990s
Authors: Pisani Michael J. , Pagán José A.
Published: November 2003

Abstract.  Using microdata from the 1993 and 1998 Living Standards Measurement Survey (LSMS) of Nicaragua, this paper analyzes the propensity of informal sector workers to queue for formal sector employment as well as employer behavior related to the selection of individuals from the informal sector queue. The nature of the queue is also examined over time to determine informal sector workers’ response to national market‐based reforms. The results indicate that informal workers do indeed queue for formal sector employment and the nature of the queue has become more pronounced during the time period under consideration.
On Labor Policies Affecting Investment in General Human Capital
Authors: Sato Yasuhiro , Sugiura Hiroaki
Published: November 2003

Abstract.  This paper develops a search model including workers’ investments in general human capital and investigates the effects of labor policies such as subsidies to human capital investment and unemployment benefits on the accumulation of human capital. It is shown that the equilibrium is not optimal because workers underinvest in human capital or firms open too many vacancies in comparison with the number of unemployed workers. Comparative statics show that an increase in subsidies to human capital investment adds to the number of vacancies per unemployed worker and to workers’ investments in human capital and that an increase in unemployment benefits decreases them. Finally, labor policies that remove the distortion are explored.
Effect of iron sucrose on human peritoneal mesothelial cells
Authors: Brȩborowicz M. , Polubinska A. , Tam P. , Wu G. , Brȩborowicz A.
Published: November 2003

Background  Iron supplementation is often required in uraemic patients with anaemia. Peritoneal cavity was proposed as an alternative intravenous route for iron infusion in patients treated with peritoneal dialysis. We studied the effect of iron sucrose (Venofer®) on the function of human peritoneal mesothelial cells maintained in in vitro culture.

Materials and methods  In in vitro experiments on human peritoneal, the mesothelial effect of elemental iron (in conc. 0·0001–1 mg mL−1) present in Venofer® on their viability, growth and synthesis of IL‐6 was studied. Additionally we evaluated with a fluorescent probe (2′,7′‐dichlorodihydro‐fluorescein diacatate) generation of reactive oxygen species in cells exposed to iron sucrose. We also measured accumulation of iron in the cytoplasm of mesothelial cells after their in vitro exposure to Venofer®.

Results  In in vitro conditions iron induces a dose‐dependent inhibition of viability of the mesothelial cells as reflected by inhibition of the cells growth by 34% at Fe 0·1 mg mL−1 vs. control (P < 0·05) increased release of lactate dehydrogenase (LDH) from the cytosol: 67·1 ± 30·3 mU mL−1 at Fe 1 mg mL−1 vs. 7·9 ± 6·4 in control group (P < 0·001), and reduced synthesis of IL‐6: 209 ± 378 pg mg−1 cell protein at Fe 1 mg mL−1 vs. 38674 ± 4146 pg mg−1 cell protein in controls (P < 0·001). Cytotoxicity of iron towards mesothelial cells was enhanced in vitro when it was tested in presence of the dialysis fluid. Iron used in vitro at concentration 0·0001 mg mL−1 and greater induces generation of oxygen‐derived free radicals in mesothelial cells. Furthermore, iron is taken by these cells and stored in their cytosol, resulting in stimulation of the intracellular generation of free radicals.

Conclusions  We conclude that iron used in the form of iron sucrose is cytotoxic to human peritoneal mesothelial cells. Accumulation of iron sucrose within cytoplasm of these cells may lead to induction of its chronic cytotoxic effect.
A Functional variant of the iNOS gene flanking region is associated with LAD coronary artery disease: an autopsy study
Authors: Kunnas T. A. , Mikkelsson J. , Ilveskoski E. , Tanner M. M. , Laippala P. , Penttilä A. , Perola M. , Nikkari S. T. , Karhunen P. J.
Published: November 2003

Background  Recent studies using reporter gene constructs have indicated significant differences in the promoter activity of inducible nitric oxide synthase (iNOS) gene variants. Although the exact role of iNOS in atherogenesis is unclear, it is possible that this variation site may influence the extent of coronary artery disease (CAD).

Methods  We amplified these (AAAT) repeat variants from the NOS2A gene (denoted iNOS R4 and iNOS R5) from 325 Finnish men included in the Helsinki Sudden Death Study, and studied their association with indices of stenosis and atherosclerosis of the left anterior descending artery (LAD), right coronary artery (RCA) and left circumflex artery (LCX). In order to understand the effect of iNOS genotype on different stages of CAD, our study population was divided into age groups.

Results  In the LAD, the progression of atherosclerosis seemed to be more pronounced in the 4/5 genotype carriers than in those with the 4/4 genotype when the different age groups were compared. More specifically, statistically significant differences between the genotypes were found in the subgroup of men aged > 55 years. In this group, men carrying the rare R4/5 genotype presented higher mean values of stenosis percentages (55% vs. 42%, P = 0·008), larger areas of fatty streaks (10·4% vs. 5·9%; P = 0·01) and complicated lesions (3·5% vs. 1·3%; P = 0·001) compared with the R4/4 carriers. No significant association of iNOS genotypes with stenosis and atherosclerosis of RCA and LCX was found.

Conclusions  It appears unlikely the R4/5 genotype plays a major role in the pathogenesis of CAD, as it was not associated with stenosis and atherosclerosis in RCA and LCX. However this genotype may have some role in more pronounced CAD, as seen in the LAD.
Bilateral buccal radicular groove in maxillary incisors: case report
Authors: Kerezoudis N. P. , Siskos G. J. , Tsatsas V.
Published: November 2003

Aim  To present the rare localization of a radicular groove on the buccal aspect of a tooth and to discuss the pathology and management of the concomitant endo‐periodontal defect.

Summary  Bilateral buccal radicular grooves were found on the maxillary central incisors of a 60‐year‐old female Caucasian. One groove was associated with deep local pocketing resulting in pulp necrosis and the formation of a periodontal–endodontic lesion. After endodontic treatment of the affected tooth, periodontal surgery was performed during which an apicoectomy was carried out on the root‐filled tooth. Both the buccal grooves were removed by grinding, the roots were planed with curettes and a guided‐tissue regeneration technique applied using amelogenin (Emdogain, Biora, Sweden). Following a period of 2 years, re‐examination showed excellent healing with the complete elimination of the periodontal pocket on both incisors and significant radiographic evidence of bone regeneration.

Key learning points 

Deep radicular grooves can predispose to pulp necrosis and the establishment of combined periodontal–endodontic lesions.

Evaluation of clinical signs and appropriate diagnostic tests are of paramount importance in order to prevent incorrect diagnosis and treatment.

Endodontists must be capable of performing advanced periodontal regeneration techniques during endodontic surgery.
Effect of nitric oxide synthase inhibitor (L‐NAME) on substance P‐induced vasodilatation in the dental pulp
Authors: Hsu Y.‐Y. , Jou Y.‐T. , Wong R. , Karabucak B. , Simchon S. , Kim S.
Published: November 2003

Aim  To investigate the vasodilator mechanisms of pulpal vessels, especially the involvement of nitric oxide (NO), during pulpal inflammation.

Methodology  Eleven cats were prepared for intra‐arterial administration of test agents through a lingual artery. The pulpal blood flow was measured by laser Doppler flowmetry from ipsilateral mandibular canine teeth. By using the NO synthase (NOS) inhibitor NG‐nitro l‐arginine methyl ester (L‐NAME), the effects of L‐NAME on various vasodilators, such as Substance P (SP)‐, calcitonin‐gene related peptide (CGRP)‐, and papaverine‐induced vasodilatation, were compared in vivo in 11 feline dental pulps.

Results  L‐NAME pretreatment potentiates SP‐induced vasodilatation for a duration of approximately 5 h. The increase of pulpal blood flow ranged from 91.47 to 109.91%, which was significantly different from SP injection alone (48.79%, P < 0.05). Other vasodilators such as CGRP and papaverine did not respond to L‐NAME pretreatment.

Conclusions  This study demonstrates that NOS inhibitor L‐NAME administration alone has insignificant effects on pulpal blood flow, although L‐NAME pretreatment can potentiate SP‐induced vasodilatation, probably via increased activity in the enzyme guanylate cyclase. CGRP and papaverine did not respond to L‐NAME pretreatment, indicating that they are not mediated via an endothelium‐dependent mechanism.
The influence of organic load on the antimicrobial activity of different concentrations of NaOCl and chlorhexidine in vitro
Authors: Sassone L. M. , Fidel R. , Fidel S. , Vieira M. , Hirata R.
Published: November 2003

Aim  To evaluate bacterial growth after contact with sodium hypochlorite (NaOCl; 1 and 5%) and chlorhexidine (CHX; 0.12, 0.5 and 1%) in vitro with or without the addition of organic material (bovine serum albumin (BSA) 0.5%).

Methodology  Bacterial samples (American Type Culture Collection® (ATCC)) of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum were kept in contact with each irrigating solution for varying intervals of time: immediately (t0), 5 min (t5), 15 min (t15) and 30 min (t30). Each test was repeated 10 times. In half of the specimens, 0.5% BSA was added as organic material in an attempt to simulate the organic tissue present in the root canal system. Bacterial growth under appropriate condition of incubation was evaluated and compared for each microorganism at all time intervals.

Results  A 0.12% CHX solution did not eliminate E. faecalis at any time interval. One percent CHX eliminated all strains, as did both NaOCl concentrations. BSA did not interfere substantially with the antimicrobial activity of any of the irrigating solutions.

Conclusions  Under the condition of this study, a 0.12% CHX solution was ineffective at killing E. faecalis.
Lymphangiogenesis in human dental pulp
Authors: Pimenta F. J. G. S. , Sá A. R. , Gomez R. S.
Published: November 2003

Aim  To investigate the impact of inflammation on lymphangiogenesis in human dental pulp.

Methodology  Eleven samples of dental pulp without inflammation and 11 dental pulps with moderate to intense mononuclear cell inflammatory infiltrate associated with dentine caries were selected. The streptavidin–biotin complex stain was used to detect CD31, vascular endothelial growth factor receptor‐3 (VEGFR‐3) and α‐smooth muscle actin. The number of lymphatic vessels was obtained by counting the number of vessels positive for CD31 and VEGFR‐3 and negative for α‐smooth muscle actin.

Results  The results demonstrated that the mean number (±SD) of vessels positive for CD31 and VEGFR‐3 (lymphatic vessels) in the group with inflammation (6.09 ± 1.81) was statistically higher (P = 0.0123) than the mean number in the group without inflammation (3.73 ± 2.20).

Conclusion  Increased co‐immunostaining of CD31 and VEGF‐3 in vessels associated with human dental pulp inflammation occurred, which suggests lymphangiogenesis.
Comparative in vivo analysis of the sealing ability of three endodontic sealers in post‐prepared root canals
Authors: Kopper P. M. P. , Figueiredo J. A. P. , Della Bona A. , Vanni J. R. , Bier C. A. , Bopp S.
Published: November 2003

Aim  To compare the sealing ability of the endodontic sealers AH Plus, Sealer 26 and Endofill in premolar teeth of dogs exposed to the oral cavity after post‐preparation.

Methodology  Forty teeth with two canals each underwent root canal cleaning and shaping. Before filling, the canals were randomly distributed into three groups according to the sealer to be used: Group 1 – AH Plus; Group 2 – Sealer 26; and Group 3 – Endofill (Dentsply, Indústria e Comércio Ltda.). Immediately after filling, the gutta percha and sealer were partially removed from the canals, leaving material only in the apical third of the root. The teeth were temporarily sealed with glass ionomer sealer for 72 h to ensure setting. The coronal seal was then removed and the canals were exposed to the oral cavity for 45 days. The animals were euthanased and their mandibles and maxillae were removed. After abundant irrigation with distilled water, the canals were dried and filled with India ink. The teeth were sealed again for 96 h before extraction. The roots of the extracted premolars were separated and stored in labelled test tubes. The roots were cleared and the extent of dye penetration was measured with a 20× stereoscopic magnifying lens.

Results  Statistical analysis revealed that there were significant differences between the sealers studied (P < 0.001). Means for the extent of dye penetration for AH Plus, Endofill and Sealer 26 were, respectively, 0.13, 2.27 and 3.08 mm.

Conclusions  After 45 days exposure to the oral cavity, none of the sealers was capable of preventing leakage and coronal dye penetration. There were significant differences between the sealers studied, in terms of mean dye penetration.
Incidence of rotary ProFile instrument fracture and the potential for bypassing in vivo
Authors: Al‐Fouzan K. S.
Published: November 2003

Aim  To determine the incidence of rotary ProFile instrument fracture and the potential for bypassing in molar teeth in vivo.

Methodology  Four hundred and nineteen maxillary and mandibular first and second molars (1457 canals) were cleaned and shaped by two endodontists with new and used sets of nickel–titanium ProFile .04 taper rotary instruments. Each set of instruments was used in five molars and was steam‐autoclaved before use. The canals were instrumented using passive instrumentation and a crown‐down preparation technique. Instruments were examined both before and after use to evaluate whether breakage or deformation had occurred. All canals were instrumented to at least a size 30 at the working length.

Results  Nineteen instruments demonstrated visible signs of plastic deformation and were discarded and replaced, whilst 21 instruments underwent intracanal fracture during treatment. Amongst these, 14 fractured in the apical third, whilst the remaining seven fractured in the middle third. Seven instruments were bypassed, and treatment was completed. There was a significantly greater number of instrument fractures with the size 20 ProFile than with the other sizes, especially after the second time of use (P < 0.05).

Conclusions  Prolonged clinical use of ProFile nickel–titanium instruments increased their fracture rate. One‐third of fractured instruments were bypassed.
The relationship of intracanal medicaments to postoperative pain in endodontics
Authors: Ehrmann E. H. , Messer H. H. , Adams G. G.
Published: November 2003

Aim  To investigate the relationship of postoperative pain to three different medicaments placed in the root canal after a complete biomechanical debridement of the root canal system in patients presenting for emergency relief of pain.

Methodology  Two hundred and twenty‐three teeth belonging to 221 patients presenting as emergencies to the Royal Dental Hospital of Melbourne were included in the study. Inclusion was limited to patients with a diagnosis of pulp necrosis and acute apical periodontitis. All teeth underwent conventional root canal treatment, which involved the instrumentation to the apices of each canal at the first visit. Canals were instrumented using a stepback technique and hand‐files along with irrigants using Milton's (1% sodium hypochlorite) solution followed by 15% EDTAC. The canals were dried and one of the following three medicaments was inserted into the canal in random sequence: Group 1: Ledermix paste (Lederle Pharmaceuticals, Division of Cyanamid, Wolfratshausen, Germany); Group 2: calcium hydroxide paste (Calcipulpe, Septodont, France); and Group 3: no dressing.

Before dismissal, the preoperative pain experienced on the previous night was recorded using a visual analogue pain scale. Patients were then instructed to record the degree of pain experienced 4 h after treatment and daily for a further 4 days.

Results  The mean score pain for all three groups was between 42 and 48 prior to treatment being commenced. After 4 days, the pain score for Group 2 was 10, for Group 3 was 7 and for Group 1 was 4. Mean preoperative pain level was 44.4 (of a maximum 100) for all groups, and declined by 50% (to 22.1) after 24 h. Patients in Group 1 (Ledermix) experienced significantly less (P = 0.04) postoperative pain than those in the other two groups. There was no significant difference between Group 2 (calcium hydroxide) and Group 3 (no dressing).

Conclusion  Under the conditions of this study, painful teeth with acute apical periodontitis that had been dressed with Ledermix paste gave rise to less pain than that experienced by patients who had a dressing of calcium hydroxide or no dressing at all. Ledermix is an effective intracanal medicament for the control of postoperative pain associated with acute apical periodontitis, with a rapid onset of pain reduction.
Root canal preparation with FlexMaster: asessment of torque and force in relation to canal anatomy
Authors: Hübscher W. , Barbakow F. , Peters O. A.
Published: November 2003

Aim  To investigate physical parameters of FlexMaster nickel‐titanium instruments while preparing curved canals in maxillary molars in vitro.

Methodology  A torque‐testing platform was used to prepare root canals in 11 extracted human maxillary molars with FlexMaster rotary instruments. Peak torque and force was registered along with numbers of rotations required to shape the canals. Canals were divided into ‘wide’ and ‘constricted’ groups depending on canal volumes assessed by microcomputed tomography. Resistance to cyclic fatigue was also tested. Mean scores for each instrument type were calculated and statistically compared using anova and Scheffé post hoc tests.

Results  Mean torque varied between 0.1 ± 0.1 and 0.8 ± 0.5 N cm while mean force ranged from 4.2 ± 2.0 to 7.3 ± 3.5 N. Mean numbers of rotations totalled up to 18. All three variables registered showed weak correlations to preoperative canal volumes (P < 0.01) and differed significantly between ‘wide’ and ‘constricted’ canals (P < 0.001). Numbers of rotations to fracture in a cyclic fatigue test were between 348 and 1362.

Conclusion  FlexMaster instruments generated low torque scores and were highly resistant to cyclic fatigue, whilst three instruments fractured in extremely narrow canals. Consequently, more research is required to limit fracture incidence and to optimize instrumentation guidelines.
Diagnosis and root canal treatment of a mandibular second premolar with three root canals
Authors: Rödig T. , Hülsmann M.
Published: November 2003

Aim  To present a case of a mandibular second premolar with three root canals.

Summary  An accurate diagnosis of the morphology of the root canal system is a prerequisite for successful root canal treatment. A review of the literature reveals a low incidence of all types of premolars with three root canals. Diagnostic means such as preoperative radiographs and examination of the pulp chamber floor aid the location of root canal orifices. The diagnostic and therapeutic problems concerning premolars with unusual anatomy are described on the basis of a clinical example. A case report describes the successful treatment of a mandibular second premolar with three root canals.

Key learning points 

Clinicians should be aware of unusual root canal anatomy in mandibular premolars.

Radiographs exposed at two different horizontal angles and their careful interpretation facilitate the search of additional root canals.

The use of magnification and additional lighting are recommended for the clinical examination of the pulpal floor.
Comparison of neurotoxicity of root canal sealers on spontaneous bioelectrical activity in identified Helix neurones using an intracellular recording technique
Authors: Asgari S. , Janahmadi M. , Khalilkhani H.
Published: November 2003

Aim  To evaluate the neurotoxic effects of two endodontic sealers, AH‐26 and Roth 801, on firing excitability and action potential configuration of F1 neural cells in the suboesophageal ganglia of Helix aspersa.

Methodology  A conventional intracellular current clamp technique was used to study the blocking effects of AH‐26 and Roth 801 on ionic currents underlying the action potential of F1 nerve cells. The sealers were prepared according to the manufacturers' directions and were applied to the bathing media in two ways: invasive (0.05 mL of total mixture of each sealer was applied at a distance of 3 mm from the cell), or gradual (0.05 mL of the extract of each dissolved mixture of sealers in normal Ringers solution was perfused).

Results  When applied in an invasive mode, both sealers reduced the duration, the amplitude of action potentials and the amplitude of after‐hyperpolarization potentials significantly and led to dramatic changes in action potential configuration. In the gradual mode of application, AH‐26 showed a biphasic action; it first increased the excitability and then decreased the action potential parameters, while Roth 801 exhibited solely blocking effects.

Conclusions  Both sealers had significant inhibitory effects on excitability of F1 neuronal cells.
Chelating agents in root canal treatment: mode of action and indications for their use
Authors: Hülsmann M. , Heckendorff M. , Lennon Á.
Published: November 2003

Chelating agents were introduced into endodontics as an aid for the preparation of narrow and calcified root canals in 1957 by Nygaard‐Østby. A liquid solution of ethylenediaminetetraacetic acid (EDTA) was thought to chemically soften the root canal dentine and dissolve the smear layer, as well as to increase dentine permeability. Although the efficacy of EDTA preparations in softening root dentine has been debated, chelator preparations have regained popularity recently. Almost all manufacturers of nickel–titanium instruments recommend their use as a lubricant during rotary root canal preparation. Additionally, a final irrigation of the root canal with 15–17% EDTA solutions to dissolve the smear layer is recommended in many textbooks. This paper reviews the relevant literature on chelating agents, presents an overview of the chemical and pharmacological properties of EDTA preparations and makes recommendations for their clinical use.
Phagocytosis ofCandida albicansand Superoxide Anion Levels in Ring Dove (Streptopelia risoria) Heterophils: Effect of Melatonin
Authors: Terrón M. P. , Cubero J. , Barriga C. , Ortega E. , Rodríguez. A. B.
Published: November 2003

We observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased the phagocytosis of inert particles (latex beads), and also provoked a decline in superoxide anion levels of those phagocytes. In the present study, we wanted to corroborate whether melatonin acts on the oxidative metabolism that accompanies the respiratory burst during phagocytosis by inducing a more effective phagocytic activity at the same time as exerting an antioxidant effect to eliminate and/or scavenge the free radicals left over after the destruction of the foreign material. To this end, we evaluated the ingestion and destruction ofCandida albicans(live particles) by ring dove (Streptopelia risoria) heterophils after different times of incubation (30 and 60 min) with physiological concentrations of melatonin (50 pg/ml diurnal and 300 pg/ml nocturnal), as well as with a pharmacological concentration 23 × 106 pg/ml (100 µm) of the hormone. In parallel, using the same times of incubation, we evaluated the oxidative metabolism by determining the superoxide anion levels (O2−·). The results show that melatonin, at all the times and concentrations studied, increases both the phagocytosis index (number ofC. albicansphagocytosed by 100 heterophils) and the candidicide power (percentage ofC. albicanskilled of those ingested by 100 heterophils). The effect was dose‐dependent. With respect to the oxidative metabolism accompanying the digestion and destruction, there was a decline in superoxide anion levels after incubation with all of the concentrations of the hormone studied. The effect was dose‐dependent and most pronounced at 60 min. These results thus corroborate the proposal that melatonin enhances the phagocytic function at the same time as neutralizing the oxidative stress derived from this immune function.
Monoaminergic Activity in Subregions of Raphé Nuclei Elicited by Prior Stress and the Neuropeptide Corticotropin‐Releasing Factor
Authors: Summers C. H. , Kampshoff J. L. , Ronan P. J. , Lowry C. A. , Prestbo A. A. , Korzan W. J. , Renner K. J.
Published: November 2003

Corticotropin‐releasing factor (CRF) coordinates neuroendocrine responses to stressful stimuli; one mechanism through which CRF may modulate hypothalamic‐pituitary‐adrenal axis activity is via actions on neuromodulatory systems such as serotonergic systems. Recent electrophysiological studies and the distribution of CRF receptors within midbrain and pontine raphé nuclei suggest that stress and CRF may have actions on topographically organized subpopulations of serotonergic neurones. We compared the effects of vehicle or intracerebroventricular r/hCRF injections (0, 0.1, 1 or 10 µg) in rats previously maintained in home cages or restrained for 1 h, 24 h before injection, on monoamine and monoamine metabolite tissue concentrations in the dorsal (lateral wings, rostral midline, caudal midline), median (rostral, caudal) and interfascicular raphé subdivisions of the midbrain and pontine raphé nuclei, using brain microdissection and high‐performance liquid chromatography with electrochemical detection. At the lowest dose studied (0.1 µg), CRF infusions in previously stressed rats decreased 5‐hydroxytryptophan (5‐HTP) and 5‐hydroxyindoleacetic acid (5‐HIAA) concentrations only within the rostral median raphé nucleus. At higher doses, CRF infusions in previously stressed rats increased tissue concentrations of 5‐HTP, serotonin (5‐HT), or the serotonin metabolite, 5‐HIAA, within rostral (but not caudal) regions of the median and dorsal raphé nuclei. By contrast, restraint stress alone had no effect on tissue concentrations of 5‐HTP, 5‐HT or 5‐HIAA measured 24 h later in any subdivision, while CRF injections in rats not previously exposed to restraint stress, with few exceptions, also had no effect. These results suggest that the effects of CRF on serotonergic function are context‐dependent, dose‐dependent, and regionally specific within subdivisions of the brainstem raphé nuclei.
Evidence From Studies on Co‐Cultures of TtT/GF and AtT20 Cells That Annexin 1 Acts as a Paracrine or Juxtacrine Mediator of the Early Inhibitory Effects of Glucocorticoids on ACTH Release
Authors: Tierney T. , . Christian H. C , . Morris J. F , Solito E. , . Buckingham J. C
Published: November 2003

Annexin 1 (ANXA1) is a key mediator of the inhibitory effects of glucocorticoids on adrenocorticotropic hormone (ACTH) release, which develop within 1–2 h of a steroid challenge. Our previous studies, which showed that (i) ANXA1 is expressed principally by the nonsecretory folliculo‐stellate cells in the pituitary gland; (ii) glucocorticoids cause the exportation of ANXA1 from these cells; and (iii) corticotrophs express specific ANXA1 binding sites, led us to propose that ANXA1 serves as a paracrine or juxtacrine mediator of glucocorticoids. To address this hypothesis, we examined ANXA1‐dependent glucocorticoid actions in co‐cultures of murine corticotroph (AtT20 clone D1) and folliculo‐stellate (TtT/GF) cell lines. ANXA1 mRNA and protein were found in abundance in TtT/GF cells but neither was detectable in the AtT20 cells. AtT20 cells (alone and in co‐culture with TtT/GF cells) responded to corticotropin‐releasing hormone (CRH) (0.1–1 µm) with increased ACTH release. The CRH‐stimulated release of ACTH from AtT20 cells cultured alone was unaffected by preincubation with dexamethasone (Dex, 100 nm); by contrast, in co‐cultures of AtT20 and TtT/GF cells, the steroid readily inhibited the secretory response to CRH. The effects of Dex on ACTH release were mimicked by N‐terminal ANXA1 fragments (ANXA1Ac2−26, 2 µg/ml and ANXA11‐188, 0.1 ng/ml) and reversed by mifepristone (1 µm) and by an antisense oligodeoxynucleotide (ODN) to ANXA1 (50 nm) but not by control ODNs. The antisense ODN also specifically blocked the Dex‐induced externalization of ANXA1 from TtT/GF cells. Immunofluorescence imaging of the co‐cultures localized the exported protein to the vicinity of the AtT20 cells and identified ANXA1 binding sites on these cells. These results provide functional and histological evidence to support our premise that the early inhibitory effects of glucocorticoids on ACTH release are dependent upon paracrine/juxtacrine actions of ANXA1 derived from folliculo‐stellate cells.
The Diurnal Modulation of Hormonal Responses in the Rat Varies with Different Stimuli
Authors: Kalsbeek A. , Ruiter M. , La Fleur S. E. , Van Heijningen C. , Buijs R. M.
Published: November 2003

The circadian clock, located in the suprachiasmatic nuclei (SCN) of the hypothalamus not only controls the basal daily temporal organization of many neuroendocrine functions, but also its responsiveness. We studied the time‐of‐day influence on plasma changes in adrenocorticotropic hormone (ACTH), corticosterone, glucagon and leptin concentrations elicited by an insulin‐induced hypoglycaemic event. Male Wistar rats were exposed to an insulin challenge at six different times during the light/dark cycle. The time‐of‐day of exposure markedly affected the responses of all four hormones studied. Generally, the magnitude of the different hormone responses correlated with their basal daily release pattern (i.e. the responses of ACTH and corticosterone were largest around lights off, and glucagon and leptin responses were most pronounced during the dark period). With regard to the hormones of the hypothalamic‐pituitary‐adrenal axis, the presently reported time‐of‐day dependent modulation is completely opposite to that previously reported for novelty or restraint. Therefore, these findings provide further support for the existence of at least two different neural pathways that are able to activate the hypothalamic‐pituitary‐adrenal axis, and provide different substrates for modulation by the biological clock. This observation warrants a thorough examination of possible functional explanations for the observed differences.
Effects of Agouti‐Related Protein on Metabolism and Hypothalamic Neuropeptide Gene Expression
Authors: Korner J. , Wissig S. , Kim A. , Conwell I. M. , Wardlaw S. L.
Published: November 2003

The hypothalamic melanocortin system regulates feeding in part through interaction of the appetite stimulating peptide, agouti‐related protein (AGRP), and the anorectic peptide, α‐melanocyte stimulating hormone, a peptide derived from the pro‐opiomelanocortin (POMC) polyprotein. Central administration of AGRP induces hyperphagia and increased gain in body weight in rodents, but may also exert metabolic effects even when hyperphagia is prevented. In the present studies, the effects of AGRP on hypothalamic neuropeptide gene expression and metabolism were examined in the rat. Central administration of AGRP for 3‐ and 7‐day periods resulted in hyperphagia, increased body weight and increased plasma leptin and insulin concentrations compared to saline‐injected controls. Hypothalamic concentrations of Pomc mRNA were also increased by 27% and 44% (in 3‐ and 7‐day experiments, respectively). The hypothalamic concentration of Agrp mRNA was unchanged after 3 days, but was significantly decreased by 33% after 7 days of AGRP infusion. To determine if these changes were dependent upon AGRP‐induced hyperphagia, pair‐fed rats with restricted food intake receiving central administration of AGRP were also studied. In the absence of hyperphagia, intracerebralventricular administration of AGRP caused significant increases in plasma leptin and insulin concentrations (two‐fold and 1.5‐fold, respectively) and fat pad mass. A significant increase in hypothalamic Pomc mRNA concentrations was not detected in pair‐fed rats. In contrast, Agrp mRNA concentrations remained suppressed by 45% in the pair‐fed group after 7 days of AGRP infusion despite equal body weight compared to saline controls. The ratio of hypothalamic Pomc to Agrp mRNA was elevated two‐fold in ad libitum and pair‐fed AGRP‐injected rats, which is consistent with increased stimulation of central melanocortin signalling pathways. Thus, central administration of AGRP exerts changes in hypothalamic neuropeptide gene expression and metabolic effects that are independent of the effects on food intake and body weight.
The Hormone Domain of the Vasopressin Prohormone is Required for the Correct Prohormone Trafficking Through the Secretory Pathway
Authors: De Bree F. M. , Van Der Kleij A. A. M. , Nijenhuis M. , Zalm R. , Murphy D. , Burbach J. P. H.
Published: November 2003

It has long been known that under intracellular conditions vasopressin associates tightly to neurophysin, which is present in the same prohormone. As the association has been suggested to play a role during hormone biosynthesis, its role was studied in a cellular context by expressing mutant vasopressin precursors in Neuro2A cells. Mutant vasopressin precursors, in which the association between the vasopressin and neurophysin domains was prevented either by deleting the vasopressin domain from the precursor or by substitution of the essential Tyr2 residue in vasopressin for Gly, were neither processed nor targeted into secretory granules. Rather, both provasopressin mutants were retained in the endoplasmic reticulum. Our results demonstrate that the vasopressin domain is crucial for correct trafficking of the prohormone through the secretory pathway, and suggest that vasopressin–neurophysin association provides correct prohormone folding in the endoplasmic reticulum.
Oestrogen Receptor‐α and ‐β Immunoreactivity in Gonadotropin‐Releasing Hormone Neurones after Ovariectomy and Chronic Exposure to Oestradiol
Authors: Legan S. J. , Tsai H.‐W.
Published: November 2003

Oestradiol exerts negative‐ and positive‐feedback actions on luteinizing hormone (LH) secretion by modulating gonadotropin‐releasing hormone (GnRH) release. Furthermore, a chronic increase in circulating oestradiol in either young ovariectomized (OVX) rats, or in middle‐aged persistent oestrous (PE) rats, causes a gradual attenuation of LH surges until the positive‐feedback action of oestradiol disappears. Based on these findings, and on the equivocal evidence regarding a direct action of oestradiol on GnRH neurones, we tested the hypothesis that chronic oestradiol abolishes LH surges by decreasing the proportion of GnRH neurones containing oestrogen receptor (ER)α or β. Regularly cycling rats were ovariectomized, and half immediately received oestradiol. Three days, or 2 or 4 weeks later, rats were perfused at 18.00 h, and GnRH was colocalized with ERα or ERβ by immunocytochemistry. ERβ was expressed in 76% of GnRH neurones, whereas virtually no GnRH cells were immunopositive for ERα. The proportion of GnRH cells expressing ERα or β in OVX rats was not altered by oestradiol or time after OVX, and this was the case regardless of their medial to lateral, or rostral to caudal location. The results indicate that the mechanisms for the positive‐feedback action of oestradiol, and the loss of LH surges in OVX rats after chronic oestradiol, are not mediated by changes in the proportion of oestrogen‐receptor containing GnRH neurones.
Controls on isoprene emission from trees in a subtropical dry forest
Authors: LERDAU M. , KELLER M.
Published: November 2003

Isoprene emission from vegetation is the single most important source of photochemically active reduced compounds to the atmosphere. We present the first controlled‐environment measurements of isoprene emission from leaves of tropical forest trees. Our studies were conducted in the Guanica State Forest in Puerto Rico. We report the effects of temperature and light variations on biogenic isoprene emissions during 1995. Maximum emission rates varied among species from 0 to 268 nmol m−2s−1. Values at the upper end of this range of maximum emission rates are 2–3 times higher than values reported from any temperate taxa. Isoprene emission showed strong sensitivity to light and temperature variations. In contrast to temperate plants, whose emissions tend to saturate at a light intensity of ∼1000 μmol m−2s−1, emissions from the tropical species increased with light intensity up to 2500 μmol m−2s−1. The temperature optima for emissions from these plants were similar to those previously reported for temperate plants: ∼40 °C. The high maximum emission rates and lack of light saturation indicate that estimates of isoprene emission from tropical forests need to be revised upwards.
Internal and external photoprotection in developing leaves of the CAM plant Cotyledon orbiculata
Authors: BARKER D. H. , SEATON G. G. R. , ROBINSON S. A.
Published: November 2003

Leaves of the CAM plant Cotyledon orbiculata produced a dense epidermal wax which decreased the absorption of light, possibly functioning as an external photoprotective mechanism (Robinson et al. 1993). However, developing leaves did not accumulate wax until after 21 d with full wax coating not achieved until at least 35 d. In addition, young leaves had lower rates of electron transport than mature leaves. Leaf development therefore occurs at higher incident PFD than that experienced by the mature leaves, and, for young leaves, can lead to an increase in the proportion of light energy which is excess to requirements and must be dissipated non‐photochemically. Changes in the photosynthetic capacity, PSII efficiency, rate of energy dissipation, and the content of chlorophyll (Chi), carotenoids, wax and anthocyanins were followed in developing leaves of C. orbiculata in an attempt to elucidate the relative importance of the various photoprotective mechanisms during leaf ontogeny. The largest pools of xanthophyll cycle pigments (on a Chi basis) were found in the waxless, young leaves and were correlated with greater levels of energy dissipation activity. The importance of xanthophyll cycle‐dependent energy dissipation in young C. orbiculata leaves prior to development of a reflective wax covering, and full photosynthetic capacity which for CAM plants includes appreciable nocturnal acid accumulation, is discussed. Also, we consider the possibility that anthocyanin pigments in the upper and lower epidermis may increase reflectivity and act as external photoprotectants.
Analysis of limitations to CO2 assimilation on exposure of leaves of two Brassica napus cultivars to UV‐B
Authors: ALLEN D. J. , MCKEE I. F. , FARAGE P. K. , BAKER N. R.
Published: November 2003

Apex and Bristol cultivars of oilseed rape (Brassica napus) were irradiated with 0.63 W m−2 of UV‐B over 5 d. Analyses of the response of net leaf carbon assimilation to intercellular CO2 concentration were used to examine the potential limitations imposed by stomata, carboxylation velocity and capacity for regeneration of ribulose 1,5‐bis‐phosphate on leaf photosynthesis. Simultaneous measurements of chlorophyll fluorescence were used to estimate the maximum quantum efficiency of photosystem II (PSII) photochemistry, the quantum efficiency of linear electron transport at steady‐state photosynthesis, and the light and CO2‐saturated rate of linear electron transport. Ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) content and activities were assayed in vitro. In both cultivars the UV‐B treatment resulted in decreases in the light‐saturated rate of CO2 assimilation, which were accompanied by decreases in carboxylation velocity and Rubisco content and activity. No major effects of UV‐B were observed on end‐product inhibition and stomatal limitation of photosynthesis or the rate of photorespiration relative to CO2 assimilation. In the Bristol cultivar, photoinhibition of PSII and loss of linear electron transport activity were observed when CO2 assimilation was severely inhibited. However, the Apex cultivar exhibited no major inhibition of PSII photochemistry or linear electron transport as the rate of CO2 assimilation decreased. It is concluded that loss of Rubisco is a primary factor in UV‐B inhibition of CO2 assimilation.
Endotoxin Tolerance Inhibits Lipopolysaccharide‐Initiated Acute Pulmonary Inflammation and Lung Injury in Rats by the Mechanism of Nuclear Factor‐κB
Authors: Qu J. , Zhang J. , Pan J. , He L. , Ou Z. , Zhang X. , Chen X.
Published: November 2003

In this study, the effect of endotoxin tolerance on lipopolysaccharide (LPS)‐initiated pulmonary inflammation, the local production of tumour necrosis factor‐α (TNF‐α) and the cytokine‐induced neutrophil attractant (CINC), as well as the activation of nuclear factor‐κB (NF‐κB) and its subunit composition, were examined in vivo. Endotoxin tolerance was reproduced by four consecutive daily intraperitoneal injections of 0.6 mg/kg of Escherichia coli 055:B5 LPS. Compared with control rats, endotoxin‐tolerant rats failed to increase the permeability of pulmonary microvascular or recruit neutrophil to lung tissue upon restimulation with 6 mg/kg of LPSs. Pretreatment with LPSs inhibited the protein level of TNF‐α in bronchoalveolar lavage fluid (BALF) and mRNA expression of CINC in lung tissue in response to subsequent LPS stimulation. These changes were accompanied by the suppression of activation of NF‐κB, including the low level of total amount of DNA‐binding activity and high percentage of non‐transactive p50 homodimers. These data demonstrate that endotoxin tolerance can alleviate the LPS‐induced acute neutrophilic pulmonary inflammation in rats and can inhibit the proinflammatory cytokines in lung and suggest that endotoxin tolerance might result from the unresponsiveness of NF‐κB and persistent high percentage of p50 homodimers. Therefore, the phenomenon of endotoxin tolerance might be used as a strategy for the prevention or treatment of LPS‐associated acute respiratory distress syndrome in which excessive or dysregulated inflammation leads to acute lung injury.
Phenotypic Features of Peripheral Blood Leucocytes During Early Stages of Human Infection with Trypanosoma cruzi
Authors: Sathler‐Avelar R. , Lemos E. M. , Reis D. D. , Medrano‐Mercado N. , Araújo‐Jorge T. C. , Antas P. R. Z. , Corrêa‐Oliveira R. , Teixeira‐Carvalho A. , Elói‐Santos S. M. , Favato D. , Martins‐Filho O. A.
Published: November 2003

We performed a cross‐sectional flow cytometric analysis of peripheral blood mononuclear cells to evaluate human immunologic status during early stages of Trypanosoma cruzi infection in children. We identified major immunological features corresponding to three proposed phases of disease: early acute (EA) phase, late acute (LA) phase and recent chronic (RC) phase. EA phase was accompanied by expansion of conventional B cells, up‐regulation of CD54 on monocytes and down‐regulation of CD54 on T cells and not associated with monocyte‐activation phenotypes or changes of natural killer (NK) population. LA phase was characterized by a selective increase in a distinct lineage of NK cells (CD16+CD56–), as well as a persistent expansion of B cells and down‐regulation of CD54 on T cells. RC phase showed persistent low levels of CD54 molecule on T cells and an increase of B cells, mainly triggered by expansion of the B1‐cell subset, as well as increased expression of human leucocyte antigen (HLA‐DR) by monocytes. These findings reinforce the hypothesis that T. cruzi‐derived antigens are able to activate NK cells before the development of T‐cell‐mediated immunity. Moreover, our data support previous findings of increased levels of B1 lymphocytes during human Chagas' disease and show that this event is already present during initial stages of chronic infection.
Elevated Serum Heat‐Shock Protein 70 Levels in Patients with Acute Infection: Use of an Optimized Enzyme‐Linked Immunosorbent Assay
Authors: Njemini R. , Lambert M. , Demanet C. , Mets T.
Published: November 2003

Heat‐shock proteins (Hsps) are highly conserved throughout evolution and evoke great interest both in basic biology and in medicine. They are expressed in small quantities under normal conditions, and their expression can be strongly induced by several stressors. Although their action is basically intracellular, it is now obvious that these proteins can be released into the extracellular environment from viable cells. In this study, the human Hsp 70 serum concentrations were determined using an optimized, cost‐effective enzyme‐linked immunosorbent assay (ELISA). The average intra‐assay variation was 6%, whereas the average interassay variation was 9%. The sensitivity of the assay was 10 ng/ml, and spiking experiments showed recoveries between 101 and 109%. As an application of the technique, we have investigated the serum levels of human Hsp 70 in patients with infection and in healthy subjects. Our data show significantly higher levels of Hsp 70 (P  = 0.003) in patients compared to control subjects. Positive correlations were noticed between the serum levels of Hsp 70 and various markers of inflammation (IL‐6; r = 0.579, P = 0.009, TNF‐α; r  = 0.552, P  = 0.012, IL‐10; r  = 0.361, P = 0.002). We conclude that Hsp 70 is involved in inflammation of infectious origin. The interindividual variation in the serum concentration of Hsp 70 precludes the use of serum Hsp 70 levels to distinguish patients from healthy subjects.
Two Doses of Daclizumab in Conjunction with Low‐Dose Cyclosporine, Mycophenolate Mofetil and Steroids Resulted in a Low Incidence of Acute Rejection after Renal Transplantation
Authors: Ekberg H. , Persson N. H. , Källen R. , Gül‐Baykurt N.
Published: November 2003

Five doses of daclizumab, given initially after kidney transplantation, reduce the rate of acute rejection (AR). Without cyclosporin A (CsA), a protocol, including daclizumab, mycophenolate mofetil (MMF) and corticosteroids (CSs), has recently shown efficacy in terms of graft function and survival. The rate of AR was relatively high, however. In this single‐centre study, a CsA low‐dose regimen was combined with two doses of daclizumab (1 mg/kg day 0 and 14), plus MMF (2 g) and CS. Forty‐three cadaver donor renal recipients were included. Following the onset of graft function, target trough levels of CsA were 150–200 ng/ml for 90 days, then 100–150 ng/ml. One year AR rate was 23% (n = 10) and events occurred at a median of 2.9 months (range from 9 days to 9.6 months). Delayed graft function (DGF) (absent spontaneous reduction of serum creatinine day 1) was 51%. Graft survival was 95% and patient survival 98% after 1 year. With respect to our previous experience, we used CsA, azathioprine and CSs (n = 223) from 1988 to 1995, and the rate of AR was 57%. From 1996 to 1998, standard CsA doses, MMF and CS (n = 67) resulted in 31% AR. Median time to AR was 0.8 and 1.0 month, and the rate of DGF was 20 and 22%, respectively. This CsA low‐dose protocol, including two doses of daclizumab, MMF and CS, resulted in a reduction and delay of AR episodes and excellent graft function, graft survival and patient survival, despite an increase in DGF.