bluuebunny/crossref_metadata_2025 huggingface dataset:
Infant respiratory symptoms in relation to mite allergen exposure
Authors: van Strien RT , Verhoeff AP , van Wijnen JH , Doekes G , de Meer G , Brunekreef B
Published: June 2003

The relationship between the Dermatophagoides pteronyssinus (Der p) I content of house dust and the respiratory symptoms reported for young infants was studied. One hundred and four infants, aged 3-15 months, were selected during July-September 1993 through the Dutch postnatal health care service, using a short screening questionnaire to identify mothers with respiratory allergy to house dust and/or pets. Forty-eight were selected from this group of mothers ("high risk" infants) and 56 infants were selected when neither of the parents reported allergy or chronic respiratory symptoms ("low risk" infants). All homes were visited in October 1993. Dust samples were collected from the infant's mattress and from other places in the home, and the Der p I content was measured in dust extracts. The results indicate that on more than half of the mattresses, the Der p I level was over 2,000 ng.g-1, the level suggested to be associated with an increased risk of sensitization. Information on respiratory symptoms ("wheeze" and "prolonged cough") experienced since birth was obtained by questionnaire from one of the parents on the dust sampling day. The occurrence of respiratory symptoms in the infants appeared to be positively related to the Der p I concentration of the dust. Although no objective measurements of respiratory symptoms were available, the results of this study suggest that exposure to mite allergen in early life may lead to respiratory symptoms that are suggestive of airway obstruction in the first year of life.
The effect of sleep deprivation on sleep states, breathing events, peripheral chemoresponsiveness and arousal propensity in healthy 3 month old infants
Authors: Thomas DA , Poole K , McArdle EK , Goodenough PC , Thompson J , Beardsmore CS , Simpson H
Published: June 2003

We wished to investigate the effects of sleep deprivation on sleep, arousal propensity, respiratory events and peripheral chemoresponses in healthy infants, since these effects might be relevant to mechanisms concerned with some cases of sudden infant death syndrome. Paired observations were made overnight during natural sleep and following sleep deprivation, in a randomized fashion, in 15 healthy infants aged 78 (7) days (mean (SD)). Polysomnograms were recorded and sleep was scored using Anders' criteria. Respiratory events were categorized into central, mixed and obstructive apnoeas. Peripheral chemoresponses were measured during quiet sleep from the respiratory response to two-breath alternations in fractional inspiratory oxygen (F1, O2) (0.42 and 0.00). Arousal propensity was determined from awakening and arousal thresholds to graded photic and auditory stimuli during quiet sleep, and from spontaneous awakenings and limb movements. Compared with natural sleep, following sleep deprivation infants maintained a greater proportion of quiet sleep (39 vs 44%). There was no measurable change in arousal propensity. During quiet sleep, obstructed breathing events tended to be more common after sleep deprivation (0.1 vs 0 events.h-1) and the expiratory time during baseline breathing increased significantly (1.27 vs 1.58 s) although the decrease in respiratory rate was not significant (32 vs 30 breaths.min-1). Peripheral chemoresponses altered significantly, alternations in tidal volume/inspiratory time (VT/tI) as a measure of inspiratory drive increased after sleep deprivation (9 vs 21%). In conclusion, following short-term sleep deprivation in infancy, respiratory control alters, peripheral chemoresponsiveness increases in magnitude and the timing of baseline breathing alters, without any detectable alteration in arousal propensity. This state may be associated with an increased vulnerability to obstructive respiratory events.
Right ventricular dysfunction in obstructive sleep apnoea: reversal with nasal continuous positive airway pressure
Authors: Nahmias J , Lao R , Karetzky M
Published: June 2003

The incidence and pathogenesis of right ventricular dysfunction in obstructive sleep apnoea (OSA) remains controversial. Using nuclear ventriculography, the prevalence of right ventricular dysfunction (RVD) was therefore determined in obese patients with OSA, as well as their clinical characteristics, arterial blood gas values, spirometry and sleep parameters. The reversibility of RVD was evaluated after long-term use of nasal continuous positive airway pressure (nCPAP). We studied 112 obese patients with OSA by nuclear ventriculography, 35 with RVD (Group 1), 77 without RVD (Group 2), and 14 patients without OSA as controls (Group 3). Repeat nuclear ventriculography was performed in seven patients who used nCPAP nightly for 6-24 months. The mean right ventricular ejection fractions (RVEF) were 31%, 47% and 44% in Groups 1, 2 and 3, respectively. Group 1 also had a lower left ventricular ejection fraction (LVEF) of 55 vs 63% in Group 2. The OSA groups did not differ in mean spirometric or arterial blood gas values. Group 1 had a lower mean nocturnal arterial oxygen saturation (Sa,O2) of 82 vs 87% in Group 2, and a longer apnoea duration of 22.3 vs 19.2 s. All but two patients in Group 1 had either awake alveolar hypoventilation or an apnoea + hypopnoea index > 40 disordered breathing events.h-1. Repeat nuclear ventriculography after nCPAP revealed an increase in RVEF from 30 to 39%. In conclusion, right ventricular dysfunction is common in obstructive sleep apnoea, but it is reversible with nasal continuous positive airway pressure treatment and appears to be related to nocturnal oxygen desaturation.
Effects of exercise and CO2 inhalation on intersubject variability in ventilatory and heart rate responses to progressive hypoxia
Authors: Sato F , Nishimura M , Igarashi T , Yamamoto M , Miyamoto K , Kawakami Y
Published: June 2003

Although the ventilatory and heart rate responses to hypoxia are known to vary widely among subjects, it is not known how exercise or hypercapnia influence the intersubject variability of these responses. If the intersubject variability increases under such conditions, the inherent response of individuals will have more impact on ventilation and heart rate under a variety of hypoxic conditions during exercise or with hypercapnia than at rest or with normocapnia. Seventeen healthy male volunteers underwent tests to measure ventilatory response to isocapnic progressive hypoxia three times respectively: at rest; during CO2 inhalation (end-tidal carbon dioxide tension (PET,CO2) raised by 5 torr from the baseline level); and during mild exercise with a cycle ergometer (12.5 W) in a supine position. The mean (SEM) value of hypoxic ventilatory response (HVR) (delta minute ventilation (V'E)/delta arterial oxygen saturation (Sa,O2) was significantly increased both in the exercise and hypercapnic runs compared with that in the control run (0.45 +/- 0.12, 0.34 +/- 0.08, respectively, vs 0.12 +/- 0.02 L.min-1/% fall), although the respiratory pattern was different under the two loaded conditions. The intersubject variation in HVR was also significantly increased during the two loaded conditions compared with the control, although a significant correlation remained between the control value and that obtained during either loaded condition (r = 0.66 and r = 0.60, respectively). The heart rate (HR) response evaluated by the slope factor (delta HR/delta Sa,O2) was not significantly different either in the mean value or in the intersubject variability among the three experimental conditions. In conclusion, exercise or CO2 inhalation not only increase the slope value of HVR but also amplify the intersubject variability of the response. In contrast, the HR response to hypoxia evaluated as a slope factor does not change with exercise or CO2 inhalation.
Co-cultivation of rat pneumocytes and bovine endothelial cells on a liquid-air interface
Authors: Gueven N , Glatthaar B , Manke HG , Haemmerle H
Published: June 2003

The blood-air barrier is a most important functional element of the lung but little information is available about the cells constituting this barrier in vivo. The aim of the present study was to create an in vitro model of the blood-air barrier that would allow investigation of cellular interactions and alveolar metabolism, and would be suitable for in vitro drug screening. Rat pneumocytes and bovine microvascular endothelial cells were grown on opposite sides of microporous polycarbonate filters, as immersion, perfusion and liquid-air interface (LAI) cultures. The effects of culture conditions on cell morphology were examined by light and transmission electron microscopy. For immersion and perfusion co-cultures, both compartments were supplied with culture medium. In contrast, for liquid-air interface studies, only the endothelial cell compartment was continuously supplied with serum-free medium, whilst the type II pneumocytes were ventilated with air. The pneumocytes lost their morphological characteristics when using immersion or perfusion co-cultures. Under liquid-air interface conditions, they retained most of their characteristic morphological features when compared to the intact blood-air barrier. A subset of primary type II pneumocytes retained its differentiated phenotype, with cuboidal morphology, lamellar bodies and apical microvilli. These type II pneumocytes appeared to be connected by tight junctions to cells expressing morphological characteristics of type I pneumocytes. As shown herein, the liquid-air interface co-culture possesses many morphological characteristics of the intact blood-air barrier. In summary, this article describes the design of an artificial blood-air barrier, in which rat pneumocytes were cultivated with bovine microvascular endothelial lung cells on opposing sides of a microporous polycarbonate filter. We conclude that it might be a promising in vitro model for studies of molecular transport via the blood-air barrier, the investigation of repair mechanisms after alveolar injury, or as an in vitro screening system.
Sodium metabisulphite causes epithelial damage and increases sheep tracheal blood flow and permeability
Authors: Wells UM , Hanafi Z , Widdicombe JG
Published: June 2003

Inhaled sodium metabisulphite (MBS) causes bronchoconstriction, cough and microvascular leakage. We have studied its effects on tracheal blood flow, potential difference (PD) and the permeability from tracheal lumen to venous blood of a low molecular weight hydrophilic tracer, 99mtechnetium-labelled diethylenetriamine penta-acetic acid (99mTc-DTPA) in anaesthetized sheep. Flow was measured in tracheal artery and blood from a cannulated tracheal vein collected for 5 min periods. The tracheal lumen was filled with Krebs-Henseleit solution (KH) containing 99mTc-DTPA for six to eight 15 min periods. During the third or fourth period, MBS (1, 20 or 100 mM) was washed into the tracheal lumen for 15 min. MBS increased tracheal blood flow (venous flow (Q'v), 5-10 min MBS exposure period: 1 mM -9 +/- 18% (n = 3); 20 mM +16 +/- 5% (n = 5; p < 0.05); 100 mM +43 +/- 13% (n = 5; p < 0.05). It decreased PD in a concentration-dependent way. Venous 99mTc-DTPA concentration increased progressively to +266 +/- 176 and +958 +/- 321% 25-30 min after exposure to 20 and 100 mM MBS, respectively (p < 0.05 for both). These effects were not blocked by luminal frusemide (3-7 mM) or flurbiprofen (100-500 microM). Histological sections showed changes to the epithelial cells and large intercellular spaces. Thus, luminal sodium metabisulphite increases tracheal blood flow, reduces transmural potential difference and causes tracheal epithelial damage, leading to an increase in 99mTc-labelled diethylenetriamine penta-acetic acid permeability.
Asbestos bodies in bronchoalveolar lavage in relation to asbestos bodies and asbestos fibres in lung parenchyma
Authors: Karjalainen A , Piipari R , Mantyla T , Monkkonen M , Nurminen M , Tukiainen P , Vanhala E , Anttila S
Published: June 2003

In Finland, unlike other countries, anthophyllite asbestos has been widely used due to its domestic production in 1918-1975. In this particular context, the aim of the present study was to analyse the relationship between asbestos bodies (ABs) in bronchoalveolar lavage (BAL) fluid and the concentration of ABs and the different amphibole asbestos fibres in lung tissue. Sixty five BAL lung tissue sample pairs from patients with pulmonary disease were analysed. The concentration of ABs in BAL fluid and lung tissue was determined with optical microscopy, and the concentration, type and dimensions of asbestos fibres in lung tissue with scanning electron microscopy. There was a significant correlation between the concentrations of ABs in BAL fluid and in lung tissue (r = 0.72; p < 0.001), between the concentrations of ABs and amphibole asbestos fibres in lung tissue (r = 0.73; p < 0.001), and between the concentration of ABs in BAL fluid and the concentration of amphibole asbestos fibres in lung tissue (r = 0.64; p < 0.001). In patients who had been exposed mainly to commercial anthophyllite, significantly higher concentrations of ABs were observed per total pulmonary amphibole fibre burden, as compared to patients whose main exposure was to crocidolite/amosite. The anthophyllite fibres in lung tissue were longer than the crocidolite/amosite fibres. The relationship between asbestos body counts in lung tissue and in bronchoalveolar lavage fluid was similar to previous international observations. When using the asbestos body count to predict the underlying total pulmonary amphibole asbestos burden in Finnish patients, however, it should be borne in mind that the relationship between the two parameters seems to be different with anthophyllite as compared to crocidolite/amosite fibres.
High resolution computed tomography in patients referred for intraluminal bronchoscopic therapy with curative intent
Authors: Sutedja G , Golding RP , Postmus PE
Published: June 2003

In patients with so-called roentgenologically occult intraluminal lung tumours, an accurate assessment of tumour size, its location and peribronchial tumour extent is important prior to any intraluminal bronchoscopic therapy (IBT) with curative intent. In twenty patients with so-called occult early-stage lung cancers, clinical outcome was compared to high resolution computed tomography (HRCT) findings prior to IBT. HRCT showed peribronchial tumour extension or nodal enlargement in 7 of the 20 patients (35%), and consequently treatment policy was changed. Five of the seven died 1.5-6 months after diagnosis, one patient underwent a radical pneumonectomy after induction chemotherapy, and the remaining patient is alive with pleural metastasis. HRCT showed intraluminal tumours in 11 of the 20 patients and IBT with curative intent was given. Complete response (CR) was achieved in 10 of the 11 patients, follow-up has been 4-26 months. One patient underwent a radical lobectomy, pathological stage T1NO, after 3 months because of tumour recurrence. HRCT was inconclusive in 2 of the 20 patients with postobstructive infiltrates. IBT was unsuccessful in both these cases. High resolution computed tomography may provide supportive evidence of intra-and extraluminal tumour; thereby, helping in the assessment of patients who were judged to be suitable for intra-luminal bronchoscopic therapy with curative intent. This may lead to a change in the treatment policy. High resolution computed tomography findings are complementary to bronchoscopic, histological and cytological examinations for the proper evaluation of treatment indications in patients with occult lung cancer.
Experimental research into the pathogenesis of cobalt/hard metal lung disease
Authors: Lison D , Lauwerys R , Demedts M , Nemery B
Published: June 2003

In recent years clinical, epidemiological and experimental evidence has accumulated indicating that cobalt metal particles, when inhaled in association with other agents such as metallic carbides (hard metals) or diamond dust, may produce an interstitial lung disease termed "hard metal disease" or "cobalt lung". This article summarizes the progress accomplished in our two laboratories to understand the pathogenesis of this disease. Gaps and weaknesses in our current knowledge have also been highlighted in order to suggest potential avenues for further research. Whilst animal models have proved useful for the demonstration of the toxic synergy between cobalt and carbides (e.g. tungsten carbide), most animal models have remained descriptive and have not provided information on the mechanism for this synergy. In particular, the bizarre multinucleated giant cells which are an important hallmark of the human disease, have not been reproduced consistently in experimental animals. Since cobalt is a known sensitizer, there may also be a need to develop experimental models to test the possible involvement of immunological mechanisms in the pathogenesis of the interstitial disease. In vitro systems including macrophage cell cultures and physico-chemical tests have been useful to investigate the mechanism underlying the toxic synergy. The recent finding that, in vitro, cobalt and metallic carbides interact with oxygen to produce toxic activated oxygen species opens a new avenue of research and may offer an alternative interpretation of the fact that only a limited proportion of exposed workers develop interstitial disease. Besides the possible involvement of immunological mechanisms, it may be speculated that individuals with a lower antioxidant defence are more susceptible to the toxic effect of activated oxygen species produced by cobalt-containing dusts from hard metal.
New strategies in mechanical ventilation for acute lung injury
Authors: Burchardi H
Published: June 2003

In the fluid-filled lungs of early adult respiratory distress syndrome (ARDS) the dependent parts are compressed and atelectatic; whereas, the nondependent areas remain aerated and functional. Ventilating these considerably restricted lungs carries the risk of overinflation and ventilatory-induced lung injury (baro-volutrauma). The consequences for adjusting mechanical ventilation are: 1) reducing tidal volumes in order to avoid alveolar hyperinflation and excessive alveolar pressures; 2) considering permissive hypercapnia if adequate CO2 elimination cannot be maintained; 3) keeping open the unstable alveoli by positive end-expiratory pressure (PEEP) (external or intrinsic). However, the large variations in regional lung compliance make it improbable that an optimal external PEEP level beneficial for the whole lung will be found; 4) using intrinsic PEEP in the inverse ratio ventilation (IRV) mode which varies with differences in regional ventilatory kinetics. No clinical study has yet convincingly demonstrated the benefit of IRV compared to conventional ventilation, controlled clinical long-term trials are not yet available; and 5) using superimposed spontaneous breathing which may be considerably more effective in opening up collapsed alveoli, combined with intentional intrinsic PEEP this is achieved in airway pressure release ventilation (APRV). Other new principles of mechanical ventilation, such as "proportional assist ventilation" or "tracheal gas insufflation" must still be considered as experimental.
Continuous positive airway pressure is effective in treating upper airway oedema
Authors: Barbe F , Pons S , Togores B , Sauleda J , Soler R , Agusti AG
Published: June 2003

The case of a patient with diffuse idiopathic skeletal hyperostosis (DISH) and upper airway oedema, is described. The patient presented with alveolar hypoventilation and obstructive apnoeas during sleep. Intravenous steroids (methylprednisolone, 160 mg.day-1) for 5 days did not reduce the oedema. However, it was rapidly reversed by the use of nasal continuous positive airway pressure (nCPAP). In addition, daytime pulmonary gas exchange was improved and sleep apnoea abolished. This beneficial effect made tracheostomy unnecessary. This case report suggests that CPAP can be a potentially useful therapeutic alternative to tracheostomy in the clinical management of upper airway oedema.
Localized fibrous pleural tumour of the interlobular pleura
Authors: Sanguinetti CM , Marchesani F , Ranaldi R , Pela R , Cecarini L
Published: June 2003

Localized fibrous tumours of the pleura (LFTP) are rare, generally benign and asymptomatic neoplasms, which originate from the pleural layers. We report on the case of a 67 year old woman who had a 1.5 cm diameter pulmonary nodule in the right upper lobe, which had been found by chance. Video-assisted thoracoscopy (VAT) was used to excise the nodule. The diagnosis of localized fibrous tumour of the interlobar pleura was made on microscopic evaluation. After 17 months, the patient is well and her chest radiographic image is normal.
Benign ecology: Marietta Pallis and the floating fen of the delta of the Danube, 1912-1916
Authors: Cameron Laura , Matless David
Published: June 2003

This paper considers the work of the ecologist Marietta Pallis (1882-1963), retracing the fieldwork associated with her 1916 paper on ‘The structure and history of Plav’, the floating fen of the Danube delta. Attending to links between field and home, politics and ecology, the paper explores how field cultures are implicated in the mutual and imaginative constitution of nature and society. The paper examines the scientific culture within which Pallis operated, and the wider cultures of travel and identity within which her scientific fieldwork took place. Fieldwork was facilitated and shaped by a range of encounters with officials and informants whose presence is variously engaged with and erased in Pallis’s published account. We emphasize Pallis’s understanding of Plav as a ‘benign’ form of ecology, highlighting the political complexity of that term, and of the vitalism espoused by Pallis as part of her conservative eco-philosophical imagination.
Collecting quoits: field cultures in the history of Cornish antiquarianism
Authors: Naylor Simon
Published: June 2003

This paper traces a historical geography of antiquarianism in the English county of Cornwall, paying particular attention to the period from 1750 to 1900 and to research conducted into the region’s ancient stone monuments. The paper argues that from the mid-eighteenth century onwards Cornish antiquarianism was largely a field-based activity. After a short discussion of the work of notable eighteenth- and early nineteenth-century antiquarians the paper focuses on the labours of those in the latter half of the nineteenth century. Differences between the two periods are discussed - these, it is argued, centred around different valuations of place and method - before the anatomy of Victorian antiquarianism’s field culture is mapped out. The paper concludes with a discussion of the place of Cornish antiquarianism in wider networks of intellectual exchange.
Is cognitive-behavioural therapy a worthwhile treatment for psychosis?
Authors: Turkington Douglas , McKenna Peter J.
Published: June 2003

Cognitive-behavioural therapy (CBT) is of proven benefit for treatment of depression and has, over the past 5 years, been increasingly advocated as a treatment modality for schizophrenia. There has been considerable enthusiasm for the use of CBT in schizophrenia from psychiatrists, psychologists, psychiatric nurses and users alike. However, this enthusiasm may have precluded dispassionate evaluation of the effectiveness of this treatment. Even though an intervention is popular and is thought to be generally a ‘good thing’, we should not then take short-cuts through the evidence. In an era of limited resources every hour spent with a patient or training staff in a new technique must be justified. Is CBT really a worthwhile and effective treatment for patients with psychosis? This issue is debated by Dr Douglas Turkington, Senior Lecturer in Psychiatry in Newcastle upon Tyne and author of one of the leading texts on CBT for schizophrenia, and Dr Peter McKenna, consultant psychiatrist with the Cambridge Psychiatric Rehabilitation Service.
Psychiatric morbidity and substance use in young people aged 13–15 years: results from the Child and Adolescent Survey of Mental Health
Authors: Boys A. , Farrell M. , Taylor C. , Marsden J. , Goodman R. , Brugha T. , Bebbington P. , Jenkins R. , Meltzer H.
Published: June 2003

Background

Psychoactive substance use is strongly associated with psychiatric morbidity in both adults and adolescents.

Aims

To determine which of alcohol, nicotine and cannabis is most closely linked to psychiatric disorders in early adolescence.

Method

Data from 2624 adolescents aged 13–15 years were drawn from a national mental health survey of children. The relationship between psychiatric morbidity and smoking, drinking and cannabis use was examined by logistic regression analyses.

Results

Having a psychiatric disorder was associated with an increased risk of substance use. Greater involvement with any one substance increased the risk of other substance use. Analyses of the interactions between smoking, drinking and cannabis use indicated that the relationship between substance use and psychiatric morbidity was primarily explained by regular smoking and (to a lesser extent) regular cannabis use.

Conclusions

In this sample, links between substance use and psychiatric disorders were primarily accounted for by smoking. The strong relationship is likely to be due to a combination of underlying individual constitutional factors and drug-specific effects resulting from consumption over the period of adolescent development and growth.
Contact with treatment services among arrested drug users
Authors: London Mervyn , Canitrot Juan , Dzialdowski Adrian , Bates Robert , Gwynn Alan
Published: June 2003

Aims and Method

To identify the proportion of arrested drug misusers with prior contact with treatment services, police surgeons' records were examined over a 12-month period and compared with the records of the local drug misuse services. Both referrals and those who attended with face-to-face contact were noted.

Results

Sixty-seven per cent of drug-related cases had been referred to services prior to arrest and 58% had attended with face-to-face contact on at least one occasion. Homeless and male drug users were more likely to have had no past contact. Police surgeons treated three-quarters of the cases for opiate dependence. Drug misusers were much more likely to have had past contact with services than arrested alcohol misusers, and were more likely to reoffend.

Clinical Implications

The evidence base for motivational enhancement in the transient coercive setting of police custody is not established, and arrest referral schemes might not be cost-effective in areas where most cases have had previous contact with services. Local research may contribute to more informed decisions about these treatment-related criminal justice initiatives.
Executives have taken over the asylum: the fate of 71 psychiatric hospitals
Authors: Chaplin Robert , Peters Steve
Published: June 2003

This article gives an account of a 2-year project to establish the fate of the mental hospitals in three areas of the UK. There were two aims: to determine the proportion of mental hospitals that are currently open and to provide descriptive data on the fate of those that had closed.
Thyroid Hormone Administration to Hypothyroid Rats Restores the Mitochondrial Membrane Permeability Properties
Authors: Vacca Rosa A. , Moro Loredana , Caraccio Giovanni , Guerrieri Ferruccio , Marra Ersilia , Greco Margherita
Published: June 2003

We have investigated the effect of thyroid hormone on the mitochondrial membrane permeability properties in a hypothyroid rat model. The role played by calcium in affecting these properties has been also examined. Cyclosporin A-sensitive mitochondrial calcium efflux, swelling, and external release of matrix proteins are events that occur normally during the permeability transition process induced by calcium loading of mitochondria. We demonstrate that these events are impaired in mitochondria isolated from the liver of hypothyroid rats, even in the presence of high calcium content. However, after thyroid hormone administration to hypothyroid rats, the mitochondrial permeability transition process in response to calcium loading is restored. Consequently, mitochondrial calcium efflux, swelling, and release of matrix proteins, like glutamate dehydrogenase, malate dehydrogenase, and aspartate aminotransferase occur. These effects are abrogated by the concomitant administration of cyclosporin A. The results of the present study suggest that hypothyroidism may be a potential source of adverse effects in patients receiving cyclosporin A.
Evidence that the C Terminus of the A Subunit Suppresses Thyrotropin Receptor Constitutive Activity
Authors: Chen Chun-Rong , Chazenbalk Gregorio D. , McLachlan Sandra M. , Rapoport Basil
Published: June 2003

The TSH receptor (TSHR), unlike the LH receptor (LHR), has considerable ligand-independent adenylyl cyclase activity, a feature of pathophysiological importance. The TSHR ectodomain partially suppresses constitutive activity, an effect reversed by trypsin treatment of intact cells. Localizing the functional site of trypsin action would provide insight into how the TSHR ectodomain exerts its constraint. For this purpose, we examined the effect of trypsin on intact cells expressing a series of modified TSHR. Trypsin did not increase cAMP production by a chimeric TSH-LH receptor involving substitution of TSHR residues 261–418 (the ectodomain C terminus). In contrast, with the wild-type TSHR, trypsin enhanced constitutive activity despite mutation of the following potential tryptic cleavage sites [arginine (R) and lysine (K) residues]: 1) K565, K651, K660 in the extracellular loops of the serpentine region; 2) B subunit juxtamembrane residues K371, K401, K415; 3) A subunit residues R310, R312, K313. We previously excluded K337 and K339 from being implicated in TSHR tryptic activation. By exclusion, only one R/K cluster remains as a possible target for the functional effect of trypsin, namely K287, K290, K291, and R293. Mutation of this cluster is incompatible with TSHR cell surface expression. However, tryptic clipping at this locus would reproduce a previously demonstrated structural effect of trypsin on the TSHR, removal of about a 2-kDa polypeptide fragment extending downstream from the locus to the C terminus of the A subunit. Taken together, these data suggest that the C terminus of the A subunit functions as a suppressor of TSHR constitutive activity.
The Different Cardiac Expression of the Type 2 Iodothyronine Deiodinase Gene between Human and Rat Is Related to the Differential Response of the dio2 Genes to Nkx-2.5 and GATA-4 Transcription Factors
Authors: Dentice Monica , Morisco Carmine , Vitale Mario , Rossi Guido , Fenzi Gianfranco , Salvatore Domenico
Published: June 2003

By producing T3 from T4, type 2 iodothyronine deiodinase (D2) catalyzes the first step in the cascade underlying the effect exerted by thyroid hormone. Type 2 iodothyronine deiodinase mRNA is expressed at high levels in human heart but is barely detectable in the corresponding rodent tissue. Although the heart is a major target of thyroid hormone, the role of cardiac D2 and the factors that regulate its expression are unknown.

Here we report that the human Dio2 promoter is very sensitive to the cardiac transcription factors Nkx-2.5 and GATA-4. Nkx-2.5 transactivates a 6.5-kb human (h)Dio2-chloramphenicol acetyltransferase construct, with maximal induction reached with a 633-bp proximal promoter region. Interestingly, despite 73% identity with the corresponding human region, the rat Dio2 promoter is much less responsive to Nkx-2.5 induction. Using EMSA, we found that two sites in the human promoter (C and D) specifically bind Nkx-2.5. In coexpression studies, GATA-4 alone was a poor inducer of the hDio2 promoter; however in synergy with Nkx-2.5, it activated D2 reporter gene expression in the human, but not the rat promoter. Functional analysis showed that both C and D sites are required for the complete Nkx-2.5 response and for the Nkx-2.5/GATA-4 synergistic effect. In neonatal rat primary myocardiocytes, most of the hDio2-chloramphenicol acetyltransferase activity was suppressed by mutation of the Nkx-2.5 binding sites. Finally, a mutant Nkx-2.5 protein (N188K), which causes, in heterozygosity, congenital heart diseases, did not transactivate the Dio2 promoter and interfered with its activity in cardiomyocytes, possibly by titrating endogenous Nkx-2.5 protein away from the promoter.

In conclusion, this study shows that Nkx-2.5 and GATA-4 play prime roles in Dio2 gene regulation in the human heart and suggests that it is their synergistic action in humans that causes the differential expression of the cardiac Dio2 gene between humans and rats.
UNC-71, a disintegrin and metalloprotease (ADAM) protein, regulates motor axon guidance and sex myoblast migration inC. elegans
Authors: Huang Xun , Huang Peng , Robinson Matthew K. , Stern Michael J. , Jin Yishi
Published: June 2003

The migration of cells and growth cones is a process that is guided by extracellular cues and requires the controlled remodeling of the extracellular matrix along the migratory path. The ADAM proteins are important regulators of cellular adhesion and recognition because they can combine regulated proteolysis with modulation of cell adhesion. We report that the C. elegans gene unc-71 encodes a unique ADAM with an inactive metalloprotease domain. Loss-of-function mutations in unc-71 cause distinct defects in motor axon guidance and sex myoblast migration. Many unc-71 mutations affect the disintegrin and the cysteine-rich domains, supporting a major function of unc-71 in cell adhesion. UNC-71 appears to be expressed in a selected set of cells. Genetic mosaic analysis and tissue-specific expression studies indicate that unc-71acts in a cell non-autonomous manner for both motor axon guidance and sex myoblast migration. Finally, double mutant analysis of unc-71 with other axon guidance signaling molecules suggests that UNC-71 probably functions in a combinatorial manner with integrins and UNC-6/netrin to provide distinct axon guidance cues at specific choice points for motoneurons.
Wnt11andRet/Gdnfpathways cooperate in regulating ureteric branching during metanephric kidney development
Authors: Majumdar Arindam , Vainio Seppo , Kispert Andreas , McMahon Jill , McMahon Andrew P.
Published: June 2003

Reciprocal cell-cell interactions between the ureteric epithelium and the metanephric mesenchyme are needed to drive growth and differentiation of the embryonic kidney to completion. Branching morphogenesis of the Wolffian duct derived ureteric bud is integral in the generation of ureteric tips and the elaboration of the collecting duct system. Wnt11, a member of the Wnt superfamily of secreted glycoproteins, which have important regulatory functions during vertebrate embryonic development, is specifically expressed in the tips of the branching ureteric epithelium. In this work, we explore the role of Wnt11 in ureteric branching and use a targeted mutation of the Wnt11 locus as an entrance point into investigating the genetic control of collecting duct morphogenesis. Mutation of the Wnt11 gene results in ureteric branching morphogenesis defects and consequent kidney hypoplasia in newborn mice. Wnt11 functions, in part, by maintaining normal expression levels of the gene encoding glial cell-derived neurotrophic factor (Gdnf). Gdnf encodes a mesenchymally produced ligand for the Ret tyrosine kinase receptor that is crucial for normal ureteric branching. Conversely, Wnt11 expression is reduced in the absence of Ret/Gdnf signaling. Consistent with the idea that reciprocal interaction between Wnt11 and Ret/Gdnf regulates the branching process, Wnt11 and Ret mutations synergistically interact in ureteric branching morphogenesis. Based on these observations, we conclude that Wnt11 and Ret/Gdnf cooperate in a positive autoregulatory feedback loop to coordinate ureteric branching by maintaining an appropriate balance of Wnt11-expressing ureteric epithelium and Gdnf-expressing mesenchyme to ensure continued metanephric development.
winglesssignaling regulates the maintenance of ovarian somatic stem cells inDrosophila
Authors: Song Xiaoqing , Xie Ting
Published: June 2003

Identifying the signals involved in maintaining stem cells is critical to understanding stem cell biology and to using stem cells in future regenerative medicine. In the Drosophila ovary, Hedgehog is the only known signal for maintaining somatic stem cells (SSCs). Here we report that Wingless (Wg)signaling is also essential for SSC maintenance in the Drosophilaovary. Wg is expressed in terminal filament and cap cells, a few cells away from SSCs. Downregulation of Wg signaling in SSCs through removal of positive regulators of Wg signaling, dishevelled and armadillo,results in rapid SSC loss. Constitutive Wg signaling in SSCs through the removal of its negative regulators, Axin and shaggy, also causes SSC loss. Also, constitutive wg signaling causes over-proliferation and abnormal differentiation of somatic follicle cells. This work demonstrates that wg signaling regulates SSC maintenance and that its constitutive signaling influences follicle cell proliferation and differentiation. In mammals, constitutive β-catenin causes over-proliferation and abnormal differentiation of skin cells, resulting in skin cancer formation. Possibly, mechanisms regulating proliferation and differentiation of epithelial cells, including epithelial stem cells, is conserved from Drosophila to man.
Stem cell homeostasis in theArabidopsisshoot meristem is regulated by intercellular movement of CLAVATA3 and its sequestration by CLAVATA1
Authors: Lenhard Michael , Laux Thomas
Published: June 2003

Stem cell maintenance in the Arabidopsis shoot meristem is regulated by communication between the apical stem cells and the underlying organizing centre. Expression of the homeobox gene WUSCHEL in the organizing centre induces stem cell identity in the overlying neighbours,which then express the CLAVATA3 gene whose activity in turn restricts the size of the WUSCHEL expression domain. We have analyzed how the stem cells and the organizing centre communicate, by studying the mode of action of CLAVATA3 protein. We provide direct evidence that CLAVATA3 protein functions as a mobile intercellular signal in the shoot apical meristem that spreads laterally from the stem cells and acts both on their lateral neighbours and on the stem cells themselves to repress WUSCHELtranscription. We also show that the spread and range of action of CLAVATA3 can be limited by binding to its receptor CLAVATA1, which offers an explanation for how CLAVATA3 is prevented from entering the organizing centre and repressing WUSCHEL transcription there. This regulated spread of a secreted signalling molecule enables the shoot meristem to permit the onset of cell differentiation in the periphery, but at the same time to maintain a stable niche for its stem cells in the center.
Splits ends is a tissue/promoter specific regulator of Wingless signaling
Authors: Lin Hua V. , Doroquez David B. , Cho Soochin , Chen Fangli , Rebay Ilaria , Cadigan Ken M.
Published: June 2003

Wingless directs many developmental processes in Drosophila by regulating expression of specific target genes through a conserved signaling pathway. Although many nuclear factors have been implicated in mediating Wingless-induced transcription, the mechanism of how Wingless regulates different targets in different tissues remains poorly understood. We report here that the split ends gene is required for Wingless signaling in the eye, wing and leg imaginal discs. Expression of a dominant-negative version of split ends resulted in more dramatic reductions in Wingless signaling than split ends-null alleles, suggesting that it may have a redundant partner. However, removal of split ends or expression of the dominant-negative had no effect on several Wingless signaling readouts in the embryo. The expression pattern of Split ends cannot explain this tissue-specific requirement, as the protein is predominantly nuclear and present throughout embryogenesis and larval tissues. Consistent with its nuclear location, the split ends dominant-negative acts downstream of Armadillo stabilization. Our data indicate that Split ends is an important positive regulator of Wingless signaling in larval tissues. However,it has no detectable role in the embryonic Wingless pathway, suggesting that it is a tissue or promoter-specific factor.
Loss of Bmp7 and Fgf8 signaling in Hoxa13-mutant mice causes hypospadia
Authors: Morgan Emily A. , Nguyen Susan B. , Scott Virginia , Stadler H. Scott
Published: June 2003

In humans and mice, mutations in Hoxa13 cause malformation of limb and genitourinary (GU) regions. In males, one of the most common GU malformations associated with loss of Hoxa13 function is hypospadia,a condition defined by the poor growth and closure of the urethra and glans penis. By examining early signaling in the developing mouse genital tubercle,we show that Hoxa13 is essential for normal expression of Fgf8 and Bmp7 in the urethral plate epithelium. In Hoxa13GFP-mutant mice, hypospadias occur as a result of the combined loss of Fgf8 and Bmp7 expression in the urethral plate epithelium, as well as the ectopic expression of noggin(Nog) in the flanking mesenchyme. In vitro supplementation with Fgf8 restored proliferation in homozygous mutants to wild-type levels, suggesting that Fgf8 is sufficient to direct early proliferation of the developing genital tubercle. However, the closure defects of the distal urethra and glans can be attributed to a loss of apoptosis in the urethra,which is consistent with reduced Bmp7 expression in this region. Mice mutant for Hoxa13 also exhibit changes in androgen receptor expression, providing a developmental link between Hoxa13-associated hypospadias and those produced by antagonists to androgen signaling. Finally,a novel role for Hoxa13 in the vascularization of the glans penis is also identified.
Novel level of signalling control in the JAK/STAT pathway revealed by in situ visualisation of protein-protein interaction duringDrosophiladevelopment
Authors: Brown Stephen , Hu Nan , Hombría James Castelli-Gair
Published: June 2003

It is commonly accepted that activation of most signalling pathways is induced by ligand receptor dimerisation. This belief has been challenged for some vertebrate cytokine receptors of the JAK/STAT pathway. Here we study whether DOME, the Drosophila receptor of the JAK/STAT pathway, can dimerise and if the dimerisation is ligand-dependent. To analyse DOME homo-dimerisation, we have applied a β-gal complementation technique that allows the detection of protein interactions in situ. This technique has been used previously in cell culture but this is the first time that it has been applied to whole embryos. We show that this technique, which we renameβlue-βlau technique, can be used to detect DOME homo-dimerisation in Drosophila developing embryos. Despite DOME being ubiquitously expressed, dimerisation is developmentally regulated. We investigate the state of DOME dimerisation in the presence or absence of ligand and show that DOME dimerisation is not ligand-induced, indicating that ligand independent cytokine receptor dimerisation is a conserved feature across phyla. We have further analysed the functional significance of ligand-independent receptor dimerisation by comparing the effects of ectopic ligand expression in cells in which the receptor is, or is not, dimerised. We show that ligand expression can only activate STAT downstream targets or affect embryo development in cells in which the receptor is dimerised. These results suggest a model in which ligand-independent dimerisation of the JAK/STAT receptor confers cells with competence to activate the pathway prior to ligand reception. Thus,competence to induce the JAK/STAT signalling pathway in Drosophilacan be regulated by controlling receptor dimerisation prior to ligand binding. These results reveal a novel level of JAK/STAT signalling regulation that could also apply to vertebrates.
Mutations inArabidopsiscondensin genes disrupt embryogenesis,meristem organization and segregation of homologous chromosomes during meiosis
Authors: Siddiqui Najeeb U. , Stronghill Patricia E. , Dengler Ronald E. , Hasenkampf Clare A. , Riggs C. Daniel
Published: June 2003

Proper chromatin condensation and sister chromatid resolution are essential for the maintenance of chromosomal integrity during cell division, and is in part mediated by a conserved multisubunit apparatus termed the condensin complex. The core subunits of the complex are members of the SMC2(Structural Maintenance of Chromosomes) and SMC4 gene families. We have cloned an Arabidopsis gene, AtCAP-E1, which is a functional ortholog of the yeast SMC2gene. A second, highly homologous SMC2 gene, AtCAPE-2, was identified by the Arabidopsis genome project. SMC2 gene expression in Arabidopsis was correlated with the mitotic activity of tissues, with high level expression observed in meristematic cells. The two genes are differentially expressed with AtCAP-E1 accounting for more than 85%of the total SMC2 transcript pool. The titan3 mutant is the result of a T-DNA insertion into AtCAP-E1, but other than subtle endosperm defects, titan3 is viable and fecund. We identified a T-DNA insertion mutant of AtCAP-E2, which showed no obvious mutant phenotype,indicating that the two genes are functionally redundant. Genetic crosses were employed to examine the consequences of reduced SMC2 levels. Both male and female gametogenesis were compromised in double mutant spores. Embryo lethality was observed for both double homozygous and AtCAP-E1-/-, AtCAP-E2+/- plants;arrest occurred at or before the globular stage and was associated with altered planes of cell division in both the suspensor and the embryo. Down regulation of both genes by antisense technology, as well as in AtCAP-E1+/-, AtCAP-E2-/- plants results in meristem disorganization and fasciation. Our data are consistent with the interpretation that threshold levels of SMC2 proteins are required for normal development and that AtCAP-E2 may have a higher affinity for its target than AtCAP-E1.
An endogenous Su(Hw) insulator separates theyellowgene from theAchaete-scutegene complex inDrosophila
Authors: Golovnin Anton , Biryukova Inna , Romanova Olga , Silicheva Margarita , Parshikov Akeksander , Savitskaya Ekaterina , Pirrotta Vincenzo , Georgiev Pavel
Published: June 2003

The best characterized chromatin insulator in Drosophila is the Suppressor of Hairy wing binding region contained within the gypsyretrotransposon. Although cellular functions have been suggested, no role has been found yet for the multitude of endogenous Suppressor of Hairy wing binding sites. Here we show that two Suppressor of Hairy wing binding sites in the intergenic region between the yellow gene and the Achaete-scute gene complex form a functional insulator. Genetic analysis shows that at least two proteins, Suppressor of Hairy wing and Modifier of MDG4, required for the activity of this insulator, are involved in the transcriptional regulation of Achaete-scute.