bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lamellar subcomponents of the cuticular cell membrane complex of mammalian keratin fibres show friction and hardness contrast by AFM
Authors: Smith J. R. , Swift J. A. 
Published: March 2003

SummaryThere is a substantial body of information indicating that 18‐methyleicosanoic acid (18‐MEA) is covalently linked to the outer surface of all mammalian keratin fibres and also forms the outer β‐layer of the cuticular cell membrane complex (CCMC) which separates the cuticle cells from each other. Low cohesive forces are expected between the lipid‐containing outer β‐layer and the δ‐layer of the CCMC, thus providing a weak point for cuticular delamination and presenting a fresh layer of 18‐MEA to the newly exposed surface.We have used lateral force microscopy and force modulation atomic force microscopy (AFM) to examine human hair fibres in which the non‐covalently linked fatty acids have been removed. Examination of the lateral force images of new cuticle surfaces revealed by the attrition of overlying cuticle layers showed three separate zones of clearly defined frictional contrast. These are thought to correspond with the δ‐layer, the proteinaceous epicuticle and outer β‐layers of the CCMC. The δ‐layer was found to have a thickness of 16 nm (SD = 1 nm, n = 25), comparable to the 18.0 nm thickness measured from transverse cross‐sections of fibres with transmission electron microscopy. Force modulation AFM showed that the outer β‐layer was softer than the epicuticle and the δ‐layer. The frictional contrast was removed following treatment with methanolic KOH (0.1 mol dm−3) at 25 °C for 30 min, suggesting the hydrolysis of the thioester linkage and removal of 18‐MEA from the surface.
Stimulation of Ca2+ Entry in Lactotrophs and Somatotrophs from Immature Rat Pituitary by N‐Terminal Fragments of Proopiomelanocortin
Authors: Lorsignol Anne , Himpens Bernard , Denef Carl 
Published: March 2003

We have previously shown that 10–12 kDa N‐terminal fragments of rat proopiomelanocortin (POMC) and human POMC1–76 stimulate mitosis and/or differentiation in lactotrophs of early postnatal rat pituitary. A truncated form, POMC1–26, mimics the differentiation‐inducing but not the mitogenic action of the former peptides. To further characterize these two biological responses, the present study compared changes in the intracellular free calcium concentration ([Ca2+]i) in response to POMC1–76 and POMC1–26 in isolated pituitary cells from 14‐day‐old female rats. Calcium (Ca2+) responses were also used as a guide to determine whether the responsive cells belong to the lactosomatotroph lineage. Application of POMC1–76 or POMC1–26 induced a maintained oscillating [Ca2+]i increase in a small population of cells. Increasing doses of the peptides did not affect the magnitude and the frequency of [Ca2+]i oscillations but clearly augmented the number of responding cells. Approximately 2% of the cells responded at 0.1 nM POMC1–76 or 5 nM POMC1–26, and 11–13% of the cells responded at 10 nM and 500 nM of the respective peptides. About one‐third of the cells responsive to these peptides also showed a [Ca2+]i increase in response to growth hormone‐releasing peptide‐6 (GHRP‐6) while, in a small number of responsive cells, [Ca2+]i was depressed by dopamine, suggesting that the former cells are somatotrophs and the latter lactotrophs. This interpretation was confirmed by immunocytochemical identification of prolactin and growth hormone (GH) in the cells. Of the cells showing Ca2+ response to POMC1–76, approximately one‐third contained GH and another third prolactin. The remainder contained neither GH nor prolactin. Comparable results were obtained with POMC1–26. The rise of [Ca2+]i induced by the N‐terminal POMC peptides persisted after depletion of intracellular Ca2+ stores by thapsigargin. Removal of Ca2+ from the extracellular medium or addition of cadmium completely abolished both the POMC1–76‐and POMC1–26‐induced [Ca2+]i increase. Nifedipine inhibited the Ca2+ response to both peptides,although only in 55% of the responsive cells. Depletion of some isoforms of protein kinase C by preincubation with the phorbol ester PMA for 24 h did not modify the Ca2+ responses. In contrast, blockade of the protein kinase A pathway with Rp‐cAMPs partially inhibited the POMC1–76‐ orPOMC1–26‐induced [Ca2+]i increase. The present data show that, in immature pituitary cells, POMC1–76induces an increase in [Ca2+]i through extracellular Ca2+ influx, possibly mediated in part byprotein kinase A activation. The active domain of POMC1–76 seems to comprise its N‐terminal moiety. The data support the hypothesis that POMC1–76 exerts a specific function in the development of different members of the lactosomatotroph lineage and that the peptide mobilizes different subsets of cells within this lineage, by a mechanism determined by its concentration.
Effects of Orexins on the Hypothalamic‐Pituitary‐Adrenal System
Authors: Jászberényi M. , Bujdosó E. , Pataki I. , Telegdy G. 
Published: March 2003

AbstractThe effects of the recently identified neuropeptides orexin‐A and orexin‐B on the hypothalamic‐pituitary‐adrenal (HPA) system were investigated. An in vivo system was used to assess the central effects of both orexin‐A and orexin‐B. Different doses of the orexins (2.8–560 pmol) were administered intracerebroventricularly (i.c.v.) to adult male rats, and plasma corticosterone was used as an index of the degree of the activation of the HPA system. Both peptides exhibited a clear dose–response action, although orexin‐B proved to be less effective than orexin‐A. Pretreatment with the corticotropin‐releasing hormone (CRH) antagonist α‐helical CRH9−41 completely prevented the action of the orexins. Orexin‐A, orexin‐B or adrenocorticotropic hormone (ACTH) was further administered intraperitoneally (i.p.). While ACTH evoked a significant adrenal response, the orexins did not influence the basal secretion. Adrenal slices, oxygenized and perifused with Krebs' solution, were also treated with orexin‐A, orexin‐B or ACTH. Both orexins failed to modify the release of corticosterone, but ACTH induced a marked adrenal response. This study suggests that these appetite‐regulating peptides might activate the HPA system at a central level but neither orexin‐A nor orexin‐B appears to modulate directly the adrenal corticosterone release.
Angiotensin II Induces Inward Currents in Subfornical Organ Neurones of Rats
Authors: Ono K. , Honda E. , Inenaga K. 
Published: March 2003

AbstractThe action of angiotensin II on subfornical organ (SFO) neurones was studied using whole‐cell current and voltage‐clamp recordings in rat slice preparations. In the current‐clamp mode, membrane depolarization in response to angiotensin II was accompanied by an increased frequency of action potentials and an increased membrane conductance. In the voltage‐clamp mode, angiotensin II elicited inward currents in a dose‐dependent manner. The net angiotensin II‐induced inward currents were voltage‐independent, with a mean reversal potential of −29.8 ± 6.2 mV. Amplitudes of the angiotensin II‐induced inward currents were decreased during perfusion with a low sodium medium. The angiotensin II‐induced inward currents were blocked by the AT1 antagonist losartan, and were partially blocked by the AT2 antagonist PD‐123319. Neurones which were sensitive to angiotensin II were found in the peripheral region of the SFO, whereas neurones in the central region were less sensitive to angiotensin II. These results suggest that angiotensin II induces inward currents, with opening of nonselective cation channels through mainly AT1 receptors in a subpopulation of SFO neurones of rats.
Large Reduction in the Number of Galanin‐Immunoreactive Cells in Pancreatic Islets of Diabetic Rats
Authors: Adeghate E. , Ponery A. S. 
Published: March 2003

AbstractAlthough galanin has been shown to be present in pancreatic islet cells, there is no literature available on the pattern of distribution and the effect of galanin in the pancreas of diabetic animals or human models. The aim of this study was to examine whether galanin immunoreactivity changes after the onset of diabetes mellitus in the rat model. The present study used immunohistochemical techniques to examine the pattern of distribution of galanin–like immunoreactive cells in the pancreas of rats with streptozotocin‐induced diabetes. The effect of galanin on insulin secretion from intact rat pancreatic tissue fragments was also investigated using a radioimmunoassay technique. Numerous galanin–like immunoreactive cells were observed in both the peripheral and central regions of the islet of Langerhans of normal rat pancreas. By contrast, the islets of diabetic rat pancreas contained significantly (P < 0.0001) fewer galanin–like immunoreactive cells than nondiabetic rats. Galanin was colocalized with insulin in the islets of normal and diabetic rats. Galanin had an inhibitory effect on insulin secretion from the isolated pancreatic tissue fragments of normal and diabetic rats at all concentrations (10−12 to 10−6 M) employed. Galanin at 10−9 M caused a significant (P < 0.02) decrease in insulin secretion from normal rat pancreatic tissue fragments compared to basal. These observations indicate that galanin may play a significant role in the regulation of insulin secretion.
Leptin Regulation of Agrp and Npy mRNA in the Rat Hypothalamus
Authors: Korner J. , Savontaus E. , Chua S. C. , Leibel R. L. , Wardlaw S. L. 
Published: March 2003

AbstractAgouti‐related protein (AGRP) is synthesized in the same neurones in the arcuate nucleus as neuropeptide Y (NPY), another potent orexigenic peptide. AGRP antagonizes the action of α‐melanocyte stimulating hormone, a derivative of pro‐opiomelanocortin (POMC) at the hypothalamic MC4 receptor to increase food intake. Although leptin has been shown to regulate Agrp/Npy and Pomc‐expressing neurones, there are differences with respect to Agrp regulation in leptin receptor‐deficient mice and rats. Unlike the obese leptin receptor‐deficient db/db mouse, which exhibits upregulation of Agrp mRNA expression in the medial basal hypothalamus (MBH) compared to lean controls, the obese leptin receptor‐deficient (faf; Koletsky) rat does not exhibit upregulation of Agrp expression. To determine whether this represents a general difference between leptin receptor‐deficient mice and rats, neuropeptide gene expression was analysed in the MBH of lean and obese rats segregating for a different leptin receptor mutation, Leprfa (Zucker). Fasting in lean rats (+/fa) for 72 h significantly increased Agrp and Npy mRNA expression, and decreased Pomc mRNA expression as detected by a sensitive solution hybridization/S1 nuclease protection assay. Npy mRNA levels were significantly increased in fed obese fa/fa compared to lean rats, and further increased in the obese animals after fasting. In contrast, Agrp mRNA levels did not differ between fed lean and fed obese rats, and fasting did not significantly change Agrp levels in obese rats. To determine whether the change in Agrp expression that occurs with food deprivation in lean rats could be prevented by leptin replacement, Sprague‐Dawley rats were fasted and infused via subcutaneous osmotic micropumps for 48 h with either saline or recombinant mouse leptin. Fasting significantly increased Agrp and Npy, and decreased Pomc mRNA levels. Leptin infusion almost completely reversed these changes such that there was no significant difference between the levels in the fasted rats and those that were fed ad libitum. Thus, in fasted lean rats, Agrp and Npy are upregulated in parallel when leptin levels fall and are downregulated by leptin infusion. By contrast, the absence of a functional leptin receptor results in the upregulation of Npy but not Agrp mRNA.
Regulation of Glutamic Acid Decarboxylase 65 and 67 Gene Expression by Ovarian Steroids: Identification of Two Functionally Distinct Populations of GABA Neurones in the Preoptic Area
Authors: Curran‐Rauhut M. A. , Petersen S. L. 
Published: March 2003

AbstractGABA neurones in the preoptic area (POA) are critical for oestradiol (E2)‐dependent surge release of luteinizing hormone (LH); however, it is not clear which population(s) of POA GABA neurones is involved. The goals of the present studies were: (i) to determine whether E2 regulates GABA neurones similarly in two subdivisions of the POA that play a role in LH surge release, the rostral POA region that contains the organum vasculosum of the lamina terminalis (rPOA/OVLT), and the region containing the anteroventral periventricular nucleus (AVPV) and medial preoptic nucleus (MPN) and (ii) to determine whether GABA neurones in either or both regions exhibit temporal changes consistent with a role in the regulation of LH surge release. To accomplish these goals, we measured glutamic acid decarboxylase (GAD) 65 and 67 mRNA levels at several time points in ovariectomized (OVX), E2‐treated OVX rats exhibiting LH surge release, and in E2‐treated OVX rats in which LH surge release was blocked by prior administration of progesterone (P4). Our findings demonstrate that, despite their close proximity, GABA neurones in the AVPV/MPN region are regulated differently from those in the rPOA/OVLT. Only neurones in the AVPV/MPN region show temporal changes in GAD 67 mRNA expression that appear to be linked to positive‐feedback effects of E2 on luteinizing hormone‐releasing hormone (LHRH) and LH release. Our findings also indicate that a morning rise and an afternoon fall in GAD 67 mRNA levels marks two E2‐dependent signals required for LHRH and LH surge release. Finally, our results suggest that there are distinct E2‐induced signals to the rPOA/OVLT and AVPV/MPN regions and that these signals differentially regulate GAD 65 and 67 gene expression.
Effects of Acute Treatment with 8‐OH‐DPAT and Fluoxetine on Aggressive Behaviour in Male Song Sparrows (Melospiza melodia morphna)
Authors: Sperry T. S. , Thompson C. K. , Wingfield J. C. 
Published: March 2003

AbstractThe role of serotonin in modulating male aggressive behaviour was investigated in male song sparrows, Melospiza melodia morphna, using two different serotonergic drugs, fluoxetine and 8‐OH‐DPAT. Fluoxetine is a selective serotonin reuptake inhibitor of the neuronal reuptake pump increasing synaptic concentrations of serotonin, and 8‐OH‐DPAT is a specific serotonin (5‐HT1A) receptor agonist. The serotonergic control of aggression in passerines has not been previously investigated. We examined these behaviours within a controlled setting using a laboratory simulated territorial intrusion, with a hierarchical scale to quantify male–male aggressive behaviour. Utilizing this scale, we quantified the extent of male aggressive behaviour in two experiments. In experiment 1, song sparrows were given 100 µl, s.c. injections of either fluoxetine (10 mg/kg) or 8‐OH‐DPAT (1 mg/kg). Experiment 2 was a dose–response study using three doses of 8‐OH‐DPAT (0.1, 1 and 10 mg/kg). In both studies, aggressive behaviour was measured 1 h after injection for 10 min in response to the presence of a novel male decoy combined with playback of conspecific song. Both drugs significantly reduced male aggressive behaviour, and 8‐OH‐DPAT did so in a dose‐dependent manner. The effect of the two drugs upon general activity was also measured using infra‐red perch hop detectors. Activity levels were not effected by either fluoxetine or 8‐OH‐DPAT at all of the respective doses, indicating that the reduction in aggressive behaviour was specific. These results demonstrate that, in a passerine species, the serotonergic system negatively regulates male–male aggressive behaviour. These results further demonstrate that aggression can be effectively studied in a laboratory setting and natural aggressive responses can be elicited using this method.
Radiological examination of dental castings – a review of the method and comparisons of the equipment
Authors: Eisenburger Michael , Addy Martin 
Published: March 2003

summary The mechanical stability of crowns or bridges as well as frameworks for removable partial dentures depends on factors like thickness and metal structure. The biological compatibility can be influenced by porosities and soldered joints.Radiological testing is a non‐destructive method to check defects in dental castings. As dental precious metal alloys have high X‐ray absorption, testing of high gold alloys should be performed with a suitable X‐ray machine at a tube voltage of 120 kV since the X‐ray penetration of dental X‐ray units using a tube voltage of 70 to 80 kV is not high enough for these alloys. As the absorption of Co–Cr alloys and of titanium is much lower, these materials can be tested with a dental X‐ray apparatus.The radiographs show location and size of metal defects. They enable an examination of metal thickness and content of porosities. Metal defects reducing the biological compatibility or cast stability can be detected prior to clinical fitting.
Automated analysis for portable EMG recording of nocturnal masseter activity in bruxers
Authors: GALLO L. M. , ROMPRÉ P. , LAVIGNE G. , PALLA S. 
Published: March 2003

Facial pain of patients with craniomandibular disorders might be caused by muscle overload. In a former study (Gallo et al., 1999) we collected data on masseter EMG of healthy subjects during sleep by means of portable recorders (integration time of 500 ms). The automated analysis of the tracings yielded the normal range of activity in the natural environment. For this study, we focused on the analysis of the distribution of masseter activity in bruxers by means of the same automated system used for asymptomatic subjects.For this purpose, data from single masseter channels of polysomnographic recordings of 10 bruxers and 10 controls were reformatted as if they had been recorded by means of the portable devices. The signals were analysed for number, amplitude and duration of contraction episodes (signal portions above a threshold which could contain subthreshold portions shorter than the standby time of 5 s). The signal amplitude was expressed in percentage of the amplitude at maximum voluntary contraction (%MVC). In the bruxers, 166·8 ± 48·5 contraction episodes per night, i.e. 20·4 ± 5·7 h

−1

, with a net duration of 8·4 ± 2·4 s and an integral of the amplitude over time of 191·6 ± 74·0 %MVCs were found (controls: 96·5 ± 39, 12·9 ± 3·5, 4·7 ± 1·2 s and 99·1 ± 28·0 %MVCs, respectively). For these parameters there was a statistically significant difference between the two groups (t‐test, P < 0·01). The distribution of all contraction episodes of all bruxers according to net duration and mean amplitude was shifted towards shorter episodes with a massive presence of episodes between 60 and 70% MVC, much higher than in controls.
Short‐term effects of physiotherapy versus counselling for the treatment of myofascial pain of the jaw muscles
Authors: MICHELOTTI A. , STEENKS M. H. , FARELLA M. , PARISINI F. 
Published: March 2003

The aim of the present study was to compare the efficacy of physiotherapy and counselling for the treatment of myofascial pain of the jaw muscles. Sixty‐three consecutive myogenous TMD patients, diagnosed according to the RDC‐TMD criteria, were assigned to two treatment groups with a balanced‐block randomization. The first group received only counselling with general information about self‐care of jaw musculature. The second group received the same general information supplemented by self‐massage, application of moist heating pads and stretching exercises of the masticatory muscles.Treatment success was decided on treatment contrast (TC), based on relative changes of sufficiently large anamnestic and clinical scores (van der Glas and van Grootel, 2000). Additional measurements included pressure pain threshold (PPT) of the masseter, anterior temporalis and Achilles' tendon, pain during gum chewing and spontaneous muscle pain scores rated on visual analogue scales (VAS). Data were collected at baseline and 3 months after start of treatment. Mann–Whitney's test and Fisher's exact test were used for statistical analysis. Sixteen patients dropped out from the study: eight from the counselling and eight from the physiotherapy group. The success rate was 13 of 23 (57%) patients for counselling and 18 of 24 (75%) for the physiotherapy group (P > 0·05). There was no significant difference between groups in all the other variables. Over a short‐term period, physiotherapy, as used in this protocol, does not appear superior to counselling for the treatment of TMD myofascial pain.
Effect of modafinil on plasma melatonin, cortisol and growth hormone rhythms, rectal temperature and performance in healthy subjects during a 36 h sleep deprivation
Authors: BRUN JOCELYNE , CHAMBA GENEVIEÉVE , KHALFALLAH YADH , GIRARD PASCAL , BOISSY ISABELLE , BASTUJI HÉLEÉNE , SASSOLAS GENEVIEÉVE , CLAUSTRAT BRUNO 
Published: March 2003

Modafinil is an alerting substance which has been used successfully to treat narcolepsy. Nothing is known about its effect on hormone secretions. For this purpose, eight healthy young men were enrolled in a double blind trial to test the effects of modafinil on daily plasma melatonin, cortisol and growth hormone (GH) rhythms. Blood was sampled for hormone assays, every hour during the daytime and every 30 min during the nighttime. In addition, rectal temperature and mental performances were determined during the study which comprised 3 sessions, two weeks apart: a 24 h control session including a night with sleep (S1) and two 48 h sessions S2 and S3 with a sleep‐deprived night (N1) followed by a recovery night (N2). Modafinil (300 mg×2) or placebo were randomly attributed during N1 at 22 h and 8 h.As expected, performance was improved after modafinil administration and body temperature was maintained or increased. Plasma melatonin and cortisol profiles were similar after modafinil and placebo administration. The levels observed during the recovery and the control nights (N2) displayed no difference. For GH, during both sleep deprived nights, secretion was dramatically reduced compared with the control one, although the number of secretory episodes was unchanged.These data show that the alerting property of modafinil is not related to an alteration of hormone profiles and suggest that the acute modafinil administration is devoid of short‐term side‐effects.