bluuebunny/crossref_metadata_2025 huggingface dataset:
Recall of an oral health education programme by nursing personnel in special housing facilities for the elderly
Authors: Paulsson Gun , Söderfeldt Björn , Fridlund Bengt , Nederfors Tommy
Published: January 2004

Objectives: To investigate the recall of oral health knowledge and confidence by nursing personnel in special housing facilities for the elderly, three years after an education programme.

Design: A cross sectional design using a questionnaire.

Sample: All nursing personnel, a total of 2,901 subjects, in five municipalities in south‐western Sweden; of whom 950 had attended the programme. The response rate was 67% (1930 subjects).

Intervention: An oral health education programme consisting of four one‐hour lessons.

Results: The oral health education programme still had an effect on the participants' attitudes towards oral health three years later. When comparing the trained group (OHEP+) which attended the programme with those who did not have training (OHEP‐), the perceived ability, opportunity and the knowledge of oral health were significantly better in the former group, p<0.01 Eurther, within the OHEP‐ group who did not attend the programme there was a significant difference in the perceived ability, opportunity and the knowledge of oral health between those with a higher level of health care education, p<0.01.

Conclusions: The effect of an oral health education programme on the participants' attitudes towards oral health persists at least for three years. The data indicate that trainees with a low level of health care education benefit most.
Age and medication are significant risk factors for xerostomia in an English population, attending general dental practice
Authors: Field EA , Fear S , Higham SM , Ireland RS , Rostron J , Willetts RM , Longman LP
Published: January 2004

Objective: To study the prevalence of xerostomia in an English population, attending general dental practice and relate it to age. medication and gender.

Design Study: Cross‐sectional.

Setting: Five General Dental Practices in Merseyside, North of England.

Subjects: 1,103 adult patients attending for routine dental care. Intervention: Questionnaire administered by dentists.

Main Outcome Measures: Age, gender, systemic medication, reported oral dryness.

Results: 1,103 patients (654 females) were recruited, of whom 427 (39%) were aged 60 years or older, 26% of patients reported taking medication. The overall prevalence of xerostomia was 12.7% (males‐10.3%, females 14.4%). Age. medication and female gender were found to be significant risk factors for xerostomia, using logistic regression analysis.

Conclusions: The prevalence of xerostomia (12.7%) in an English population was lower than reported in previous North American and Swedish studies. Medication was a significant risk factor for xerostomia and a better predictor of risk status, than either age or gender.
Assessing the difference between sociodental and normative approaches to assessing prosthetic dental treatment needs in dentate older people
Authors: Srisilapanan P. , Sheiham A.
Published: January 2004

Objective: To illustrate differences in assessed need using normative and sociodental approaches to assess prosthetic treatment needs of dentate older people.

Design: A cross‐sectional study using non‐random sample.

Setting: Metropolitan area of Chiang Mai, Thailand.

Subjects: 707 older individuals, 549 of the total sample were dentate, living independently, aged 60 to 74 years.

Results: The dentate population examined consisted of 289 classified as ‘normal health’ and 44 with a nutritional problem. Of the total population, 60% (333) had a normative need for partial dentures. Excluding the 44 with a nutritional problem, 50% (146) of the NTM group had ‘impact‐related treatment need’ and of the latter 146, 69% (102) had a high propensity for health behaviour. 41% of the 102 who had ‘impact‐related’ and ‘propensity related treatment need’ had ‘accessible treatment need’. That is 14.5 per 100 of those with normative need. The gap between normative and ‘accessible need’ was greater among those with ‘general health related treatment need’ due to underweight. Of the 44 with a NTM and had a health problem, 45% (20) had a “propensity related treatment need”. 40% of the group with a ‘propensity related treatment need’ had ‘accessible treatment need’. Overall of the 44 older people with a normative need for a prosthesis and who had a health problem, only 2.4% had ‘accessible treatment need’ mainly due to lack of finance. If the treatment were subsidised then 45% of those with ‘propensity related treatment need’ would be eligible for treatment.

Conclusion: Large differences of estimated treatment need were found between a socio‐dental and a normative approach to assess prosthetic dental treatment needs of older Thai people.
Influence of psychological factors on the acceptance of complete dentures
Authors: Al Quran F , Clifford T , Cooper C , Lamey P‐J
Published: January 2004

Objectives: To assess the influence of psychological factors on the acceptance of complete dentures in a population wearing dentures judged to be clinically satisfactory.

Design: Subjects were asked to complete personality profiles and also to rate their dentures using a denture satisfaction questionnaire.

Setting: The survey was conducted in the prosthetics clinic of a teaching hospital.

Subjects: Patients were selected from those who had new complete dentures constructed in the department within the previous two years. Intervention and main outcome measures: The personality inventory was a self‐administered questionnaire comprising 240 items covering the five domains of personality. Denture satisfaction was scored on a nine item scale with four Likert type responses to each.

Results: A group of 16% consistently complained about their dentures. Statistical analysis showed that personality factors especially Neuroticism had a significant relationship with denture satisfaction.

Conclusion: Psychological factors significantly influence denture satisfaction and profiles may provide useful in predicting potential difficult denture wearers.
Developing a schedule of normative denture treatment need
Authors: McNaugher Gillian A , Benington Ian C , Freeman Ruth
Published: January 2004

Objectives: The aim of the study is to assess the reliability and validity of a schedule to determine the normative denture treatment needs of older people.

Design: The design used assessed inter‐examiner reliability (criterion validity), test‐retest reliability, and content and face validity of the schedule.

Setting: The inter‐examiner reliability study took place in a Department of Prosthetic Dentistry, the remainder of the work took place in a community setting.

Results: The results showed that the schedule in terms of an index performed well with reasonable inter‐examiner and test‐retest reliability. Difficulties however were encountered with regard to subjective judgements about denture quality and design; consequently, there was modest inter‐examiner agreement for stability, retention, and occlusal balance.

Conclusions: The findings from this preliminary work suggest that the schedule may be useful in the assessment of normative denture treatment need in a community setting. Nevertheless more work will be required to obtain further information on the validity of this new assessment measure.
Assessing expressed need and satisfaction in complete denture wearers
Authors: McNaugher Gillian A , Benington Ian C , Freeman Ruth
Published: January 2004

Objectives: The need to assess both lay and professional views of oral health is believed to be at the centre of success when providing dental health care for older patients. Self‐perceived physical (oral) health and perceptions of psychosocial functioning must be included if expressed need is to be assessed. The aim of this work was to construct an expressed need schedule and to assess the ability of this assessment to predict older community‐based patients' satisfaction with complete dentures.

Design: Survey of 260 people aged 65 years and over.

Setting: Community setting.

Main outcome measures: The participants were interviewed using a 55 item modified version of the Oral Health Impact Profile (OHIP) to assess their psychological, social and perceptions of their oral health. All participants were subjected to an oral examination.

Results: The results showed that complete denture wearers compared had greater experience of difficulties associated with oral health and psychological functioning. Factor analysis allowed the identification of three dimensions associated with psychological, social and self‐perceived physical (oral) health. When these factors were regressed with normative denture treatment need against satisfaction with complete dentures, satisfaction was characterised by high self‐perceived physical (oral) health, low social health problems and no identifiable normative need.

Conclusion: This work supports the inclusion of self‐perceived physical (oral) health and psychosocial health (expressed need) questions in a schedule when predicting satisfaction with complete dentures.
Good Clinical Practice is now Obligatory in Academic Clinical Drug Research in the European Union
Authors: Jørgensen Annette , Bach Karin Friis , Friis Karen
Published: January 2004

Abstract: By May 2004, all clinical trials in the European Union (EU) on medicinal products have to be initiated and conducted in compliance with the principles in the new directive on Good Clinical Practice (GCP). This requirement will also apply to non‐commercial trials involving registered drugs and may therefore restrain the academic clinical drug research. In Denmark, three public GCP units connected in a national network and associated with the university hospitals in Copenhagen, Odense and Aarhus have been established. The GCP units offer academic researchers the necessary quality assurance and quality control systems to ensure that clinical drug research can be performed according to GCP. The Danish initiative is presented here as a contribution to the future work with implementation of the principles of GCP in academic clinical drug research in the European Union.
Morphine‐Induced Analgesia in the Hot‐Plate Test: Comparison between NMRInu/nu and NMRI mice
Authors: Vermeirsch Hilde , Meert Theo F.
Published: January 2004

Abstract: NMRInu/nu mice are frequently used in cancer research, but their use in behavioural pain tests is unexplored. As behaviour of NMRI mice in pain tests is well‐documented, a hot‐plate test was performed comparing acute thermal nociception in NMRInu/nu and NMRI mice – untreated and morphine‐treated – to estimate the usefulness of NMRInu/nu mice for further research on cancer pain. In both strains, morphine dose‐dependently increased response latencies, number of animals reaching cut‐off times and AUC values. Yet in NMRInu/nu mice, as compared to NMRI mice, all curves were shifted to the right. In order to be comparable, cut‐off times must express a similar degree of baseline response augmentations. NMRInu/nu mice had substantially lower pre‐drug latencies, indicating a lowered threshold for painful thermal stimuli, therefore effects of morphine in NMRInu/nu mice were also analysed using a lower cut‐off time. Doing so, morphine resulted in similar effects in both strains. The effects were independent of hot‐plate temperature, because similar results were obtained using temperatures of 50 and 55 °. The different morphine sensitivity of NMRInu/nu compared to NMRI mice primarily seems to depend upon differences in thermal threshold, probably induced by the different genotype of both strains. To determine whether cancer alters pain threshold or morphine analgesia, LoVo tumour‐bearing NMRInu/nu mice were also tested. The tumour presence had no influence on withdrawal latencies or morphine efficacy. In general it can be concluded that NMRInu/nu mice with or without tumour can be used for nociceptive testing if baseline sensitivity is properly defined.
Phencyclidine‐Induced Behaviour in Mice Prevented by Methylene Blue
Authors: Klamer Daniel , Engel Jörgen A. , Svensson Lennart
Published: January 2004

Abstract: Schizophrenia is a major public health problem that affects approximately 1% of the population worldwide. Schizophrenia‐like symptoms can be induced in humans by phencyclidine (PCP), a drug with marked psychotomimetic properties. Phencyclidine disrupts prepulse inhibition of acoustic startle in rodents, a measure which has also been shown to be disrupted in schizophrenic patients. This effect is blocked by nitric oxide synthase (NOS) inhibitors, suggesting that nitric oxide plays an important role in this effect of phencyclidine. Methylene blue, a guanylate cyclase and nitric oxide syntase inhibitor, has shown therapeutic value as an adjuvant to conventional antipsychotics in the therapy of schizophrenia. The aim of the present study was to investigate if phencyclidine‐(4 mg/kg)induced disruption of prepulse inhibition could be affected by methylene blue (50 or 100 mg/kg) in mice. Furthermore, the effect of methylene blue (50 mg/kg) on phencyclidine‐(4 mg/kg)induced hyperlocomotion was investigated. The present study shows that phencyclidine readily disrupts prepulse inhibition in mice without affecting pulse‐alone trials. It was also found that methylene blue prevents the decrease in prepulse inhibition caused by phencyclidine in a dose‐related manner. Furthermore, the increase in locomotor activity caused by phencyclidine was reduced by pretreatment with methylene blue. The results from the present study further support the suggestion that the nitric oxide synthase/guanylate cyclase pathway is involved in pharmacological and behavioural effects of phencyclidine. Since phencyclidine as well exerts psychotomimetic characteristics, agents that interfere with the nitric oxide synthase/guanylate cyclase pathway may be of therapeutic value also in the treatment of schizophrenia.
Inhibition of Voltage‐Sensitive Sodium Channels by the Cannabinoid 1 Receptor Antagonist AM 251 in Mammalian Brain
Authors: Liao Chengyong , Zheng Jian , David Laurence S. , Nicholson Russell A.
Published: January 2004

Abstract: The cannabinoid 1 receptor antagonist AM 251 is known to block the inhibitory effects of endocannabinoids and synthetic cannabinoid agonists on transmitter release through an action at presynaptic cannabinoid 1 receptors in brain. We examined the ability of AM 251 to inhibit sodium channel‐dependent functions and the binding of [3H]batrachotoxinin A 20‐α‐benzoate to sodium channels in mouse brain synaptic preparations. Depolarization of synaptoneurosomes by the sodium channel site 2‐specific neurotoxin veratridine, which is abolished by tetrodotoxin, was found to be inhibited in a concentration‐dependent fashion by AM 251 (IC50=8.9 μM). Veratridine‐dependent (tetrodotoxin suppressible) release, of L‐glutamic acid and GABA from synaptosomes was also reduced by AM 251 [IC50s=8.5 μM (L‐glutamic acid), 9.2 μM (GABA)]. The binding of the radioligand [3H]batrachotoxinin A 20‐α‐benzoate to site 2 on sodium channels was displaced by AM 251 (IC50=11.2 μM). Scatchard analysis of binding showed that at its IC50, AM 251 increased (by 2.3 times) the KD of radioligand without altering Bmax, suggesting a competitive mechanism of inhibition by AM 251. Kinetic experiments indicated that AM 251 inhibits equilibrium binding by allosterically accelerating the dissociation of the [3H]‐batrachotoxinin A 20‐α‐benzoate:sodium channel complex. Our data suggest that micromolar concentrations of AM 251 are capable of reducing neuronal excitability and inhibiting release of excitatory and inhibitory transmitters through blockade of voltage‐sensitive sodium channels in brain.
Anticonvulsant Profile of Flunarizine and Relation to Na+ Channel Blocking Effects
Authors: Fischer Wolfgang , Kittner Holger , Regenthal Ralf , De Sarro Giovambattista
Published: January 2004

Abstract: The present study will summarize our findings concerning the anticonvulsant properties of the Ca2+ channel blocker flunarizine in a variety of experimental models of epilepsy. Flunarizine exhibits anticonvulsant effects against tonic seizures induced by electroshock or various chemoconvulsants in mice, however, did not protect against pentylenetetrazol‐induced clonic seizures. In the MES test, the efficacy of clinically established antiepileptics was increased by co‐medication. In the rotarod test, a minimal “neurotoxic” dose (TD50) of 18.0 mg/kg intraperitoneally was determined. In models of complex partial seizures like the hippocampal stimulation and the amygdala kindling in rats, flunarizine showed only a moderate activity. Thus, it can be suggested that the anticonvulsant potency of flunarizine in various screening tests is lower than that of standard antiepileptics such as carbamazepine and phenytoin. Concerning the possible mode of action, whole‐cell patch‐clamp experiments with cultured neonatal rat cardiomyocytes showed that flunarizine depressed the fast inward Na+ current in a concentration‐ and frequency‐dependent manner well comparable with the action of phenytoin. It is concluded that the use‐dependent inhibition of voltage‐dependent Na+ channels may essentially contribute to the anticonvulsant activity of flunarizine in models for generalized tonic‐clonic seizures. The clinical efficacy as add‐on therapy is critically discussed in view of the present data.
γ‐Hydroxybutyric Acid, Unlike γ‐Aminobutyric Acid, Does Not Stimulate Gi/Go Proteins in Rat Brain Membranes
Authors: Odagaki Yuji , Yamauchi Toshio
Published: January 2004

Abstract: γ‐Hydroxybutyric acid is a naturally occurring substance that may act as a neurotransmitter or neuromodulator to elicit several biological effects. Although the existence of a specific γ‐hydroxybutyric acid receptor has been postulated, the receptor protein itself has not been cloned yet. The current study was designed to elucidate whether γ‐hydroxybutyric acid receptors are functionally coupled with heterotrimeric G‐proteins, especially Gi/Go family, by means of high‐affinity GTPase activity and guanosine 5′‐O‐(3‐[35S]thiotriphosphate) ([35S]GTPγS) binding assays in rat brain membranes. The stimulatory effects of GABAB receptor activation were always determined in parallel as a positive control. The selective GABAB receptor agonist (±)‐baclofen stimulated the high‐affinity GTPase activity in cerebral cortical, hippocampal, and striatal membranes, whereas γ‐hydroxybutyric acid was inactive up to 1 mM in these brain regions. The optimum assay conditions for [35S]GTPγS binding to detect a receptor‐mediated activation of G‐proteins at the greatest signal to noise ratio were then probed as to the concentrations of constituents in the assay mixture (GDP, MgCl2, and NaCl) and incubation period. Even under such an optimized experimental condition, [35S]GTPγS binding was not altered by γ‐hydroxybutyric acid in the membranes prepared from cerebral cortex or hippocampus. On the other hand, the specific [35S]GTPγS binding was increased by GABAB receptor agonists in a concentration‐dependent manner, which was competitively inhibited by CGP54626, a selective GABAB receptor antagonist. These results indicate that γ‐hydroxybutyric acid receptors, if any, are not associated with G‐proteins, at least Gi/Go family.
Effects of Silymarin and Vitamins E and C on Liver Damage Induced by Prolonged Biliary Obstruction in the Rat
Authors: Muriel Pablo , Moreno Mario G.
Published: January 2004

Abstract: Oxidative stress, in particular lipid peroxidation, induces collagen synthesis. Thus, we administered various antioxidants to bile duct‐ligated rats for 28 days and lipid peroxidation, glutathione content, fibrosis, necrosis and cholestasis were evaluated. Extrahepatic cholestasis was induced by double ligation and section of the common bile duct. The study included eight groups (n=6), four groups were bile duct‐ligated and received either vitamin C (50 mg/kg/day, orally), vitamin E (400 IU/rat/day, orally), silymarin (50 mg/kg/12hr, orally) or vehicles; four groups were sham‐operated controls. Collagen content was determined by measuring hydroxyproline in liver samples; malondialdehyde was used to estimate lipid peroxidation levels; reduced and oxidized glutathione were determined fluorometrically; alanine aminotransferase and bilirubins colorimetrically. Bilirubins increased several times, alanine aminotransferase once, reduced/oxidized glutathione ratio decreased three times, lipid peroxidation and collagen increased about three‐times by biliary obstruction (p<0.05). Silymarin, vitamin E or C failed to prevent these effects significantly. It is not possible to clarify the role of oxidative stress in the fibrotic process induced by chronic biliary obstruction with the present results. Therefore, it seems reasonable to propose that a wide mixture of antioxidants, administered by the parenteral route (because cholestasis decreased the absorption of lipophilic compounds), is needed to counteract the oxidant stress produced by cholestasis.
Serotonergic facilitation of synaptic activity in the developing rat prefrontal cortex
Authors: Béïque Jean‐Claude , Chapin‐Penick Esther M. , Mladenovic Ljiljana , Andrade Rodrigo
Published: January 2004

Previous studies have outlined an important role for serotonin (5‐HT) in the development of synaptic connectivity and function in the cerebral cortex. In this study, we have examined the effects of 5‐HT on synaptic function in prefrontal cortex at a time of intense synapse formation and remodelling. Whole‐cell recordings in slices derived from animals aged postnatal (P) days 16–20 showed that administration of 5‐HT induced a robust increase in synaptic activity that was blocked by CNQX but not by bicuculline. This 5‐HT‐induced increase in glutamate‐mediated synaptic activity was pharmacologically heterogeneous as it was differentially inhibited by the receptor subtype‐selective antagonists SB‐269970, MDL 100907 and GR 113808 and thus involved 5‐HT7, 5‐HT2A and 5‐HT4 receptors. These results, obtained in juvenile cortex, contrast with those seen in adults where the increase in spontaneous excitatory postsynaptic currents (sEPSCs) was mediated solely by 5‐HT2A receptors. In developing cortex, activation of 5‐HT7, but not 5‐HT2A or 5‐HT4 receptors, elicited a robust inward current. However, the facilitation of synaptic activity mediated by all three of these receptors involved increases in both the amplitude and frequency of sEPSCs and was blocked by TTX. These results are best interpreted as indicating that all three receptor subtypes increase synaptic activity by exciting neuronal elements within the slice. No evidence was found for a postsynaptic facilitation of synaptic currents by 5‐HT. Together, these results show that the repertoire of electrophysiologically active 5‐HT receptors in prefrontal cortex is developmentally regulated, and that 5‐HT7 and 5‐HT4 receptors play a previously unsuspected role in regulating synaptic activity in this region.
Intracellular Na+ inhibits voltage‐dependent N‐type Ca2+ channels by a G protein βγ subunit‐dependent mechanism
Authors: Blumenstein Yakov , Maximyuk Olexandr P. , Lozovaya Natalia , Yatsenko Natalia M. , Kanevsky Nataly , Krishtal Oleg , Dascal Nathan
Published: January 2004

N‐type  voltage‐dependent  Ca2+ channels (N‐VDCCs) play important roles in neurotransmitter release and certain postsynaptic phenomena. These channels are modulated by a number of intracellular factors, notably by Gβγ subunits of G proteins, which inhibit N‐VDCCs in a voltage‐dependent (VD) manner. Here we show that an increase in intracellular Na+ concentration inhibits N‐VDCCs  in hippocampal pyramidal neurones and in Xenopus oocytes. In acutely dissociated hippocampal neurones, Ba2+ current via N‐VDCCs was inhibited by Na+ influx caused by the activation of NMDA receptor channels. In Xenopus oocytes expressing N‐VDCCs, Ba2+ currents were inhibited by Na+ influx and enhanced by depletion of Na+, after incubation in a Na+‐free extracellular solution. The Na+‐induced inhibition was accompanied by the development of  VD facilitation, a hallmark of a Gβγ‐dependent process. Na+‐induced regulation of N‐VDCCs is Gβγ dependent, as suggested by the blocking of Na+ effects by Gβγ scavengers and by excess Gβγ, and may be mediated by the Na+‐induced dissociation of Gαβγ heterotrimers. N‐VDCCs may be novel effectors of Na+ion, regulated by the Na+ concentration via Gβγ.
Pulmonary arterial distension and vagal afferent nerve activity in anaesthetized dogs
Authors: Moore Jonathan P. , Hainsworth Roger , Drinkhill Mark J.
Published: January 2004

Distension of the main pulmonary artery and its bifurcation are known to result in a reflex vasoconstriction and increased respiratory drive; however, these responses are observed at abnormally high distending pressures. In this study we recorded afferent activity from pulmonary arterial baroreceptors to investigate their stimulus–response characteristics and to determine whether they are influenced by physiological changes in intrathoracic pressure. In chloralose‐anaesthetized dogs, a cardiopulmonary bypass was established, the pulmonary trunk and its main branches were vascularly isolated and perfused with venous blood at pulstatile pressures designed to simulate the normal pulmonary arterial pressure waveform. Afferent slips of a cervical vagus were dissected and nerve fibres identified that displayed discharge patterns with characteristics expected from pulmonary arterial baroreceptors. Recordings were obtained with (a) chest open (b) chest closed and resealed, and (c) with phasic negative intrathoracic pressures in the resealed chest. Pressure–discharge characteristics obtained in the open‐chest animals indicated that the threshold pulmonary pressure (corresponding to 5% of the overall response) was 17.1 ± 2.9 and the inflexion point of the curve was 29.2 ± 3.3 mmHg (mean ±s.e.m). In closed‐chest animals the threshold and inflexion pressures were reduced to 12.0 ± 1.7 and 20.7 ± 1.8 mmHg. Application of phasic negative intrathoracic pressures further reduced the threshold and inflexion pressures to 9.5 ± 1.2 mmHg (P < 0.05 vs. open) and 14.7 ± 0.8 mmHg (P < 0.003 vs. open and P < 0.02 vs. atmospheric). These results indicate that under physiological conditions, with closed‐chest and phasic negative intrathoracic pressure changes similar to those associated with normal breathing, activity from pulmonary baroreceptors is obtained at physiological pulmonary arterial pressures in intact animals.
Endocannabinoid signalling selectively targets perisomatic inhibitory inputs to pyramidal neurones in juvenile mouse neocortex
Authors: Trettel Joseph , Fortin Dale A. , Levine Eric S.
Published: January 2004

Retrograde synaptic signalling has long been recognized as a fundamental feature of neural systems. However, the cellular specificity and functional consequences of fast retrograde communication are not well understood. We have focused our efforts on understanding the role that endocannabinoids play in regulating synaptic inhibition in sensory neocortex. Recent studies have implicated endocannabinoids as the retrograde signalling molecules that underlie depolarization‐induced suppression of inhibition, or DSI. This short‐term form of presynaptic depression is triggered by postsynaptic depolarization and is likely to play an important role in information processing. In the present study we investigated the cellular and synaptic specificity of endocannabinoid signalling in sensory cortex using whole‐cell recordings from layer 2/3 pyramidal neurones (PNs) in acute brain slices. We report that GABAergic interneurones that are depolarized by muscarinic receptor stimulation provided the majority of DSI‐susceptible inputs to neocortical PNs. This subclass of interneurones generated large, fast postsynaptic currents in PNs which were transiently suppressed by either postsynaptic depolarization or a brief train of action potentials. Neocortical DSI required activation of the type 1 cannabinoid receptor (CB1R) but not metabotropic glutamate or GABA receptors. Using focal drug application, we found that the DSI‐susceptible afferents preferentially synapse on the perisomatic membrane of PNs, and not on the apical dendrites. Together, these results suggest that endocannabinoid‐mediated DSI in the cortex can transiently and selectively depress a subclass of PN inputs. Although the physiological implications remain to be explored, this suppression of somatic inhibition may alter the excitability of principal neurones and thereby modulate cortical output.
Indirect sensing of insulin‐induced hypoglycaemia by the carotid body in the rat
Authors: Bin‐Jaliah I. , Maskell P. D. , Kumar P.
Published: January 2004

The most physiologically important sensors for systemic glucoregulation are located in extra‐cranial sites. Recent evidence suggests that the carotid body may be one such site. We assessed rat carotid body afferent neural output in response to lowered glucose, indirectly by measurement of ventilation, and directly by recording single or few‐fibre chemoafferent discharge,in vitro. Insulin (0.4Ukg−1min−1)‐induced hypoglycaemia (blood glucose reduced byca50% to 3.4 ± 0.1mmoll−1) significantly increased spontaneous ventilationin sham‐operated animals but not in bilateral carotid sinus nerve sectioned (CSNX) animals. In both groups, metabolic rate (measured as) was almost doubled during hypoglycaemia. The ventilatory equivalentwas unchanged in the sham group leading to a maintained control level ofP, butwas significantly reduced in the CSNX group, giving rise to an elevation of 6.0 ± 1.3mmHg inP. When pulmonary ventilation in sham animals was controlled and maintained, phrenic neural activity increased during hypoglycaemia and was associated with a significant increase inPof 5.1 ± 0.5mmHg. Baseline chemoreceptor discharge frequency, recordedin vitro, was not affected, and did not increase when the superfusate [glucose] was lowered from 10 mmto 2 mmby substitution with sucrose: 0.40 ± 0.20 Hz to 0.27 ± 0.15Hz, respectively (P> 0.20). We suggest therefore that any potential role of the carotid bodies in glucose homeostasisin vivois mediated through its transduction of some other metabolically derived blood‐borne factor rather than glucoseper seand that this may also provide the link between exercise, metabolic rate and ventilation.
Congenital hypoventilation and impaired hypoxic response in Nurr1 mutant mice
Authors: Nsegbe Elise , Wallén‐Mackenzie Åsa , Dauger Stephane , Roux Jean‐Christophe , Shvarev Yuri , Lagercrantz Hugo , Perlmann Thomas , Herlenius Eric
Published: January 2004

Nurr1, a transcription factor belonging to the family of nuclear receptors, is expressed at high levels immediately after birth. Gene‐targeted mice lacking Nurr1 fail to develop midbrain dopaminergic neurones and do not survive beyond 24 h after birth. Dopamine (DA) levels may be regulated by Nurr1, and as DA is involved in both central and peripheral respiratory control, we hypothesized that lack of Nurr1 may impair breathing and cause death by respiratory failure. We demonstrate herein that Nurr1 newborn knockout mice have a severely disturbed breathing pattern characterized by hypoventilation, numerous apnoeas and failure to increase breathing when challenged with hypoxia. In heterozygote Nurr1 mice the response to hypoxia is also altered. Furthermore, the central respiratory rhythm, generated from isolated brainstem–spinal cord preparations, exhibits impaired response to hypoxia in mice lacking Nurr1. Moreover, Nurr1 is expressed in several respiratory‐related regions of the nervous system, including the nucleus of the solitary tract, the nucleus ambiguus and the dorsal motor nucleus of the vagus nerve, and in the carotid bodies. The prominent Nurr1 expression in these areas, involved in respiratory control, along with the severe respiratory phenotype, indicates that Nurr1 plays a major role in the extrauterine adaption of respiratory control and the response to hypoxia.
Functional up‐regulation of KCNA gene family expression in murine mesenteric resistance artery smooth muscle
Authors: Fountain S. J. , Cheong A. , Flemming R. , Mair L. , Sivaprasadarao A. , Beech D. J.
Published: January 2004

This study focused on the hypothesis that KCNA genes (which encode KVα1 voltage‐gated K+ channels) have enhanced functional expression in smooth muscle cells of a primary determinant of peripheral resistance – the small mesenteric artery. Real‐time PCR methodology was developed to measure cell type‐specific in situ gene expression. Profiles were determined for arterial myocyte expression of RNA species encoding KVα1 subunits as well as KVβ1, KVα2.1, KVγ9.3, BKCaα1 and BKCaβ1. The seven major KCNA genes were expressed and more readily detected in endothelium‐denuded mesenteric resistance artery compared with thoracic aorta; quantification revealed dramatic differential expression of one to two orders of magnitude. There was also four times more RNA encoding KVα2.1 but less or similar amounts encoding KVβ1, KVγ9.3, BKCaα1 and BKCaβ1. Patch‐clamp recordings from freshly isolated smooth muscle cells revealed dominant KVα1 K+ current and current density twice as large in mesenteric cells. Therefore, we suggest the increased RNA production of the resistance artery impacts on physiological function, although there is quantitatively less K+ current than might be expected. The mechanism conferring up‐regulated expression of KCNA genes may be common to all the gene family and play a functional role in the physiological control of blood pressure.
Single‐channel recordings of a rapid delayed rectifier current in adult mouse ventricular myocytes: basic properties and effects of divalent cations
Authors: Liu Gong Xin , Zhou Jun , Nattel Stanley , Koren Gideon
Published: January 2004

The rapidly delayed rectifier current (IKr) has been described in ventricular myocytes isolated from many species, as well as from neonatal mice. However, whether IKr is present in the adult mouse heart remains controversial. We used cell‐attached patch‐clamp recording in symmetrical K+ solutions to assess the presence and behaviour of single IKr channels in adult mouse cardiomyocytes (mIKr). Of 314 patches, 158 (50.1%) demonstrated mIKr currents as compared with 131 (42.3%) for the IK1 channel. Single mIKr channel activity was rarely observed at potentials positive to −10 mV. The slope conductance at negative potentials was 12 pS. Upon repolarization, ensemble‐averaged mIKr showed slow deactivation with a biexponential time course. A selective IKr blocker, E‐4031 (1 μm), completely blocked mIKr channel activity. Extracellular Ca2+ and Mg2+ at physiological concentrations shifted the activation by ∼30 mV, accelerated deactivation kinetics, prolonged long‐closed time, and reduced open probability without affecting single‐channel conductance, suggesting a direct channel‐blocking effect in addition to well‐recognized voltage shifts. HERG subunits expressed in Chinese hamster ovary cells produced channels with properties similar to those of mIKr, except for the more‐negative activation of the HERG channels. Despite the abundant expression of mIKr, single‐channel events were rarely observed during action‐potential clamp and 5 μm E‐4031 had no detectable effect on the action potential parameters, confirming that mIKr plays at best a minor role in repolarization of adult mouse cardiomyocytes, probably because the modulatory effects of divalent cations prevent significant mIKr opening under physiological conditions.
Protein phosphatase 1 and an opposing protein kinase regulate steady‐state L‐type Ca2+ current in mouse cardiac myocytes
Authors: DuBell William H. , Rogers Terry B.
Published: January 2004

Studies have suggested that integration of kinase and phosphatase activities maintains the steady‐state L‐type Ca2+ current in ventricular myocytes, a balance disrupted in failing hearts. As we have recently reported that the PP1/PP2A inhibitor calyculin A evokes pronounced increases in L‐type ICa, the goal of this study was to identify the counteracting kinase and phosphatase that determine ‘basal’ICa in isolated mouse ventricular myocytes. Whole‐cell voltage‐clamp studies, with filling solutions containing 10 mm EGTA, revealed that calyculin A (100 nm) increased ICa at test potentials between −42 and +49mV (44% at 0mV) from a holding potential of −80mV. It also shifted the V0.5 (membrane potential at half‐maximal) of both activation (from −17 to −25mV) and steady‐state inactivation (from −32 to −37mV) in the hyperpolarizing direction. The broad‐spectrum protein kinase inhibitor, staurosporine (300 nm), was without effect on ICa when added after calyculin A. However, by itself, staurosporine decreased ICa throughout the voltage range examined (50% at 0mV) and blocked the response to calyculin A, indicating that the phosphatase inhibitor's effects depend upon an opposing kinase activity. The PKA inhibitors Rp‐cAMPs (100 μm in the pipette) and H89 (1 μm) failed to reduce basal ICa or to block the calyculin A‐evoked increase in ICa. Likewise, calyculin A was still active with 10 mm intracellular BAPTA or when Ba2+ was used as the charge carrier. These data eliminate roles for protein kinase A (PKA) and calmodulin‐dependent protein kinase II (CaMKII) as counteracting kinases. However, the protein kinase C (PKC) inhibitors Ro 31‐8220 (1 μm) and Gö 6976 (200 nm) decreased steady‐state ICa and blunted the effect of calyculin A. PP2A is not involved in this regulation as intracellular applications of 10–100 nm okadaic acid or 500 nm fostriecin failed to increase ICa. However, PP1 is important, as dialysis with 2 μm okadaic acid or 500 nm inhibitor‐2 mimicked the increases in ICa seen with calyculin A. These in situ studies identify constitutive activity of PP1 and the counteracting activity of certain isoforms of PKC, in pathways distinct from receptor‐mediated signalling cascades, as regulatory components that determine the steady‐state level of cardiac L‐type ICa.
The effect of tropomyosin on force and elementary steps of the cross‐bridge cycle in reconstituted bovine myocardium
Authors: Fujita Hideaki , Lu Xiaoying , Suzuki Madoka , Ishiwata Shin'ichi , Kawai Masataka
Published: January 2004

The role of tropomyosin (Tm) in the elementary steps of the cross‐bridge cycle in bovine myocardium was investigated. The thin filament was selectively removed using gelsolin (thin filament severing protein), and the actin filament was reconstituted from G‐actin. Tm was further reconstituted without troponin (Tn), and the kinetic constants of the elementary steps of the cross‐bridge cycle were deduced using sinusoidal analysis at pCa ≤ 4.66, pH 7.00, and 25°C. The association constant of MgATP to cross‐bridges (K1) after reconstitution of Tm was 20.7 ± 2.3 mm−1, which was about 2 × the control (untreated) myocardium (9.1 ± 1.3 mm−1). Following reconstitution of Tm, the equilibrium constant of the cross‐bridge detachment step (K2), the phosphate (Pi) association constant (K5) and the equilibrium constant of the force‐generation step (K4), which significantly changed in the actin filament‐reconstituted myocardium, recovered to those of the control myocardium. Active tension after reconstitution of Tm was 0.69 × the control myocardium, a value between the control (1.00 ×) and the actin filament‐reconstituted myocardium (0.59 ×). Tm‐reconstituted myocardium was further reconstituted with Tn, and the effect of MgATP on the rate constants (K1, K2) was studied. Following reconstitution with Tn, the myocardium regained the Ca2+‐sensitivity and the active tension became 0.83 × the control myocardium. In addition, K1 recovered to the value of the control myocardium with Tn reconstitution. These results indicate that both Tm and Tn enhance the force generated by each cross‐bridge, and that Tm is primarily responsible for the change in the kinetic constants of the elementary steps of the cross‐bridge cycle.
The Ubiquitin Ligase SCF
Fbw7
Antagonizes Apoptotic JNK Signaling
Authors: Nateri Abdolrahman S. , Riera-Sans Lluís , Costa Clive Da , Behrens Axel
Published: January 2004

Jun N-terminal kinases (JNKs) are essential for neuronal microtubule assembly and apoptosis. Phosphorylation of the activating protein 1 (AP1) transcription factor c-Jun, at multiple sites within its transactivation domain, is required for JNK-induced neurotoxicity. We report that in neurons the stability of c-Jun is regulated by the E3 ligase SCF
Fbw7
, which ubiquitinates phosphorylated c-Jun and facilitates c-Jun degradation. Fbw7 depletion resulted in accumulation of phosphorylated c-Jun, stimulation of AP1 activity, and neuronal apoptosis. SCF
Fbw7
therefore antagonizes the apoptotic c-Jun–dependent effector arm of JNK signaling, allowing neurons to tolerate potentially neurotoxic JNK activity.
Human De-Etiolated-1 Regulates c-Jun by Assembling a CUL4A Ubiquitin Ligase
Authors: Wertz Ingrid E. , O'Rourke Karen M. , Zhang Zemin , Dornan David , Arnott David , Deshaies Raymond J. , Dixit Vishva M.
Published: January 2004

Arabidopsis thaliana
De-etiolated-1 (AtDET1) is a highly conserved protein, with orthologs in vertebrate and invertebrate organisms. AtDET1 negatively regulates photomorphogenesis, but its biochemical mechanism and function in other species are unknown. We report that human DET1 (hDET1) promotes ubiquitination and degradation of the proto-oncogenic transcription factor c-Jun by assembling a multisubunit ubiquitin ligase containing DNA Damage Binding Protein-1 (DDB1), cullin 4A (CUL4A), Regulator of Cullins-1 (ROC1), and constitutively photomorphogenic-1. Ablation of any subunit by RNA interference stabilized c-Jun and increased c-Jun–activated transcription. These findings characterize a c-Jun ubiquitin ligase and define a specific function for hDET1 in mammalian cells.
Selective Differentiation of Neural Progenitor Cells by High-Epitope Density Nanofibers
Authors: Silva Gabriel A. , Czeisler Catherine , Niece Krista L. , Beniash Elia , Harrington Daniel A. , Kessler John A. , Stupp Samuel I.
Published: January 2004

Neural progenitor cells were encapsulated in vitro within a three-dimensional network of nanofibers formed by self-assembly of peptide amphiphile molecules. The self-assembly is triggered by mixing cell suspensions in media with dilute aqueous solutions of the molecules, and cells survive the growth of the nanofibers around them. These nanofibers were designed to present to cells the neurite-promoting laminin epitope IKVAV at nearly van der Waals density. Relative to laminin or soluble peptide, the artificial nanofiber scaffold induced very rapid differentiation of cells into neurons, while discouraging the development of astrocytes. This rapid selective differentiation is linked to the amplification of bioactive epitope presentation to cells by the nanofibers.
Dramatic Effects of 2-Bromo-5,6-Dichloro-1-β-
d
-Ribofuranosyl Benzimidazole Riboside on the Genome Structure, Packaging, and Egress of Guinea Pig Cytomegalovirus
Authors: Nixon Daniel E. , McVoy Michael A.
Published: January 2004

The halogenated benzimidazoles BDCRB (2-bromo-5,6-dichloro-1-β-
d
-riborfuranosyl benzimidazole riboside) and TCRB (2,5,6-trichloro-1-β-
d
-riborfuranosyl benzimidazole riboside) were the first compounds shown to inhibit cleavage and packaging of herpesvirus genomes. Both inhibit the formation of unit length human cytomegalovirus (HCMV) genomes by a poorly understood mechanism (M. R. Underwood et al., J. Virol. 72:717-715, 1998; P. M. Krosky et al., J. Virol. 72:4721-4728, 1998). Because the simple genome structure of guinea pig cytomegalovirus (GPCMV) provides a useful model for the study of herpesvirus DNA packaging, we investigated the effects of BDCRB on GPCMV. GPCMV proved to be sensitive to BDCRB (50% inhibitory concentration = 4.7 μM), although somewhat less so than HCMV. In striking contrast to HCMV, however, a dose of BDCRB sufficient to reduce GPCMV titers by 3 logs (50 μM) had no effect on the quantity of GPCMV genomic DNA that was formed in infected cells. Electron microscopy revealed that this DNA was in fact packaged within intranuclear capsids, but these capsids failed to egress from the nucleus and failed to protect the DNA from nuclease digestion. The terminal structure of genomes formed in the presence of BDCRB was also altered. Genomes with ends lacking a terminal repeat at the right end, which normally exist in an equimolar ratio with those having one copy of the repeat at the right end, were selectively eliminated by BDCRB treatment. At the left end, BDCRB treatment appeared to induce heterogeneous truncations such that 2.7 to 4.9 kb of left-end-terminal sequences were missing. These findings suggest that BDCRB induces premature cleavage events that result in truncated genomes packaged within capsids that are permeable to nuclease. Based on these and other observations, we propose a model for duplication of herpesvirus terminal repeats during the cleavage and packaging process that is similar to one proposed for bacteriophage T7 (Y. B. Chung, C. Nardone, and D. C. Hinkle, J. Mol. Biol. 216:939-948, 1990).
Active Akt and Functional p53 Modulate Apoptosis in Abelson Virus-Transformed Pre-B Cells
Authors: Gong Li , Unnikrishnan Indira , Raghavan Anuradha , Parmar Kalindi , Rosenberg Naomi
Published: January 2004

Suppression of apoptosis is an important feature of the Abelson murine leukemia virus (Ab-MLV) transformation process. During multistep transformation, Ab-MLV-infected pre-B cells undergo p53-dependent apoptosis during the crisis phase of transformation. Even once cells are fully transformed, an active v-Abl protein tyrosine kinase is required to suppress apoptosis because cells transformed by temperature-sensitive (ts) kinase mutants undergo rapid apoptosis after a shift to the nonpermissive temperature. However, inactivation of the v-Abl protein by a temperature shift interrupts signals transmitted via multiple pathways, making it difficult to identify those that are critically important for the suppression of apoptosis. To begin to dissect these pathways, we tested the ability of an SH2 domain Ab-MLV mutant, P120/R273K, to rescue aspects of thetsphenotype of pre-B cells transformed by the conditional kinase domain mutant. The P120/R273K mutant suppressed apoptosis at the nonpermissive temperature, a phenotype correlated with its ability to activate Akt. Apoptosis also was suppressed at the nonpermissive temperature by constitutively active Akt and inp53-null pre-B cells transformed with thetskinase domain mutant. These data indicate that an intact Src homology 2 (SH2) domain is not critical for apoptosis suppression and suggest that signals transmitted through Akt and p53 play an important role in the response.
Conservation of a Stepwise, Energy-Sensitive Pathway Involving HP68 for Assembly of Primate Lentivirus Capsids in Cells
Authors: Dooher Julia E. , Lingappa Jaisri R.
Published: January 2004

Previously we have described a stepwise, energy-dependent pathway for human immunodeficiency virus type 1 (HIV-1) capsid assembly in a cell-free system. In this pathway, Gag polypeptides utilize the cellular factor HP68 and assemble into immature capsids by way of assembly intermediates that have defined biochemical characteristics. Here we address whether this pathway is universally conserved among primate lentiviruses and can be observed in mammalian cells. We demonstrate that HIV-2 Gag associates with human HP68 in a cell-free system and that Gag proteins of HIV-2, simian immunodeficiency virus SIVmac239, and SIVagm associate with endogenous HP68 in primate cells, as is seen for HIV-1. Analysis of primate cells expressing lentivirus Gag proteins revealed Gag-containing complexes with the same sedimentation values as seen for previously described HIV-1 assembly intermediates in the cell-free system (10S, 80-150S, and 500S). These complexes fit criteria for assembly intermediates as judged by energy sensitivity, pattern of HP68 association, and the failure of specific complexes to be formed by assembly-incompetent Gag mutants. We also demonstrate that virus-like particles released from cells do not appear to contain HP68, suggesting that HP68 is released from Gag upon completion of capsid assembly in cells, as was observed previously in the cell-free system. Together these findings support a model in which all primate lentivirus capsids assemble by a conserved pathway of HP68-containing, energy-dependent assembly intermediates that have specific biochemical features.