bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic analysis of snoring sound in patients with simple snoring and obstructive sleep apnoea
Authors: Fiz JA , Abad J , Jane R , Riera M , Mananas MA , Caminal P , Rodenstein D , Morera J
Published: April 2003

Snoring, a symptom which may indicate the presence of the obstructive sleep apnoea syndrome (OSA), is also common in the general population. Recent studies have suggested that the acoustic characteristics of snoring sound may differ between simple snorers and OSA patients. We have studied a small number of patients with simple snoring and OSA, analysing the acoustic characteristics of the snoring sound. Seventeen male patients, 10 with OSA (apnoea/hypopnoea index (AHI) 26.2 events x h(-1)) and seven simple snorers (AHI 3.8 events x h(-1)), were studied. Full night polysomnography was performed and the snoring sound power spectrum was analysed. Spectral analysis of snoring sound showed the existence of two different patterns. The first pattern was characterized by the presence of a fundamental frequency and several harmonics. The second pattern was characterized by a low frequency peak with the sound energy scattered on a narrower band of frequencies, but without clearly identified harmonics. The seven simple snorers and two of the 10 patients with OSA (AIH 13 and 14 events x h(-1), respectively) showed the first pattern. The rest of the OSA patients showed the second pattern. The peak frequency of snoring was significantly lower in OSA patients, with all but one OSA patient and only one simple snorer showing a peak frequency below 150 Hz. A significant negative correlation was found between AHI and peak and mean frequencies of the snoring power spectrum (p<0.0016 and p<0.0089, respectively). In conclusion, this study demonstrates significant differences in the sound power spectrum of snoring sound between subjects with simple snoring and obstructive sleep apnoea patients.
Influence of moderate alcohol consumption on obstructive sleep apnoea with and without AutoSet nasal CPAP therapy
Authors: Teschler H , Berthon-Jones M , Wessendorf T , Meyer HJ , Konietzko N
Published: April 2003

Snoring worsens with high alcohol consumption. It is unclear whether moderate alcohol intake worsens sleep and breathing in subjects with obstructive sleep apnoea syndrome (OSAS), and whether alcohol increases the pressure requirement for nasal continuous positive airway pressure (CPAP). Fourteen adult males with untreated OSAS but without heart or lung disease were studied (age 53+/-9 yrs, body mass index (BMI) 33+/-5 kg x m(-2) (mean+/-SD). The subjects underwent overnight polysomnography on four occasions: control, alcohol, CPAP, and alcohol + CPAP. On the alcohol nights, the subjects drank 1.5 mL x kg(-1) body weight (BW) vodka (40% alcohol by volume) (blood alcohol with and without CPAP 0.45+/-0.1 and 0.47+/-0.2 mg x mL(-1) (mean+/-SD)). On the CPAP nights, the pressure required to prevent apnoea, snoring, and silent inspiratory airflow limitation was determined using an autotitrating nasal CPAP system (ResCare AutoSet). Alcohol and control nights were performed in random order. Without CPAP, alcohol produced a small non-significant decrease in the percentage of rapid eye movement (REM) sleep (control 11+/-2 vs alcohol 8+/-1% (mean+/-SEM)), but with CPAP there was no such effect (control 15+/-2 vs 17+/-2%; CPA x alcohol interaction p=0.015). With CPAP, slow-wave sleep in the first 2 h increased slightly with alcohol (control 39+/-6 vs alcohol 51+/-4%; p=0.004). Arousal index without CPAP increased slightly with alcohol (control 43+/-5 vs alcohol 49+/-6 events x h(-1); p=0.02). There was little or no effect of alcohol on other sleep stages, arousal index, apnoea index, apnoea/hypopnoea index, mean or longest event duration, mean or worst arterial oxygen saturation, with or without CPAP, either for the full night or for the first 2 h. There was no change in the pressure requirement for CPAP (full night: control 11.9+/-0.9 vs alcohol 12.5+/-0.9 cm H2O; first 2 h: 10.9+/-0.6 vs 11.1+/-0.8 cm H2O). Moderate alcohol intake (in the form of vodka) has little effect on breathing or saturation during sleep in subjects with mild-to-severe obstructive sleep apnoea, and no effect on the pressure required for continuous positive airway pressure in order to prevent apnoea, snoring, and flow limitation. These results cannot be extrapolated to other doses or forms of alcohol, or to subjects with concurrent heart or lung disease.
Osteoporosis in patients undergoing lung transplantation
Authors: Ferrari SL , Nicod LP , Hamacher J , Spiliopoulos A , Slosman DO , Rochat T , Bonjour JP , Rizzoli R
Published: April 2003

The occurrence of osteoporotic fractures may seriously compromise the quality of life of lung transplant recipients. However, at present, the true risk of osteoporosis in such patients is unknown. We therefore prospectively evaluated bone mass changes in patients undergoing pulmonary transplantation. Bone mineral density (BMD) of lumbar spine (LS), femoral neck (FN) and femoral shaft (FS), as well as whole body bone mineral content (WB-BMC) were measured in 21 consecutive candidates for lung transplantation (9 males and 12 females; mean+/-SD age 47+/-11 yrs). Twelve of the patients had their BMD remeasured within 6 months after surgery, and nine again after 1 year. Before transplantation, BMD at all sites as well as WB-BMC were significantly decreased as compared to the values in young healthy adults, FN being the most affected (FN -25+/-2%; LS, -12+/-4%; FS -9+/-2%, WB-BMC -15+/-4% (mean+/-SEM)). Seven out of 20 adult patients (35%) fulfilled World Health Organization (WHO) criteria for osteoporosis, i.e. BMD more than 2.5 SD below peak bone mass, whereas three had previously been diagnosed as having osteoporotic fractures of the spine or femoral neck. Within 6 months after transplantation, significant bone loss occurred, mostly at the LS level (-4.0+/-1.7%; p=0.04), despite calcium and vitamin D supplementation. Furthermore, two patients had new osteoporotic vertebral fractures. After 1 year, no further bone loss or new osteoporotic fractures were observed. In conclusion, evaluation of bone mass and prevention of bone loss should be considered early before lung transplantation. Further studies are needed to determine the efficacy of antiresorptive drugs on the prevention of accelerated bone loss and vertebral fractures after transplantation.
A laboratory comparison of four positive pressure ventilators used in the home
Authors: Smith IE , Shneerson JM
Published: April 2003

Four brands of ventilator used for noninvasive positive pressure ventilation in the home were assessed to determine their performance on a patient simulator. We tested the tidal volume (VT) preset Companion 2801 (Puritan Bennett), minute volume preset Monnal D (Taema), and two pressure preset ventilators, the Nippy (Friday Medical) and the Bilevel Positive Airway Pressure (BiPAP) (Respironics). A patient simulator was employed to investigate the relationships between VT, peak airway pressure (PAP) and mean airway pressure (MAP), the responses to an additional leak in the circuit and patient effort of a variable duration, which was modelled using a negative pressure pump. For equivalent VTs, >300 mL, the Monnal D and Nippy generated a PAP up to 100% greater than the Companion 2801 and BiPAP. When an additional leak was introduced to the circuit, the VT of the Companion 2801 and Monnal D fell by >50%, while the Nippy and the BiPAP responded by increasing flow and maintained VT close to the level achieved with no leak. When the ventilators were triggered by a simulated patient effort of 0.25 s duration with a frequency 33% greater than that of the ventilator, the minute volume increased by 41% for the Companion 2801, by 18% for the Monnal D (no change expected), and by 17% for the Nippy (less than expected), and fell by 7% for the BiPAP due to irregular triggering. When patient effort was prolonged to 1.5 s, a similar length to the inspiratory time of the ventilators, there was no further change in the minute volume of the Companion 2801 and Monnal D, while that of the Nippy and of the BiPAP increased by 38 and 71%, respectively, compared to baseline. These results show that distinct brands of ventilator respond to changes in the patient and patient circuit in different ways, which are not always predictable from a simple description of their operating principles. This should be borne in mind when choosing a positive pressure ventilator for noninvasive ventilation.
Diffuse progressive pulmonary interstitial and intra-alveolar cholesterol granulomas in childhood
Authors: Sato K , Takahashi H , Amano H , Uekusa T , Dambara T , Kira S
Published: April 2003

We describe an 18 year old male with pulmonary interstitial and intra-alveolar cholesterol granulomas (PICG), which developed to severe respiratory failure over 15 yrs. The histological diagnosis was made on the basis of open lung biopsy findings at the age of 3 yrs and autopsy at 18 yrs of age. Although the pathological features of the lung were similar to that of paediatric patients with lipoid pneumonia coexisting with pulmonary alveolar proteinosis (PAP), gastro-oesophageal reflux (GOR) and a diverse group of severe primary diseases, the patient lacked evidence for any of these. We believe the present case provides a new example of a diffuse-type of lipoid pneumonia coexisting with pulmonary alveolar proteinosis, which we call cholesterol granulomas.
Progesterone treatment in chylothorax associated with pulmonary tuberous sclerosis
Authors: Jounieaux V , Druelle S , Mayeux I , Grimault E , Charet JC
Published: April 2003

We report the case of a young woman with tuberous sclerosis who developed a chylous pleural effusion after several invasive procedures for treatment of recurring pneumothoraces. Oophorectomy was rejected by the patient and progesterone therapy initiated. Medroxyprogesterone acetate administration led to a complete disappearance of the chylothorax in 8 months. The patient was kept on therapy, and no recurrence of pleural effusion has been observed up to the present (22 months follow-up). However, a progressive deterioration in pulmonary function was observed, with a significant decrease in pulmonary transfer factor and increase in airway obstruction. In conclusion, this report demonstrates an objective benefit of progesterone therapy on chylous effusion associated with pulmonary tuberous sclerosis.
Vertebral osteomyelitis caused by thoracic empyema, or vice versa?
Authors: Liesker KR , Taconis WK , Plasmans CM , Schreurs AJ
Published: April 2003

Thoracic empyema and vertebral osteomyelitis is a rare combination. We report a case of vertebral osteomyelitis possibly caused by a progressive thoracic empyema. The causative pathogen was Escherichia coli. Computed tomographic (CT) scan and magnetic resonance imaging (MRI) suggested the diagnosis of vertebral osteomyelitis, confirmed by transthoracic needle aspiration and operative findings. Aetiology and treatment are discussed.
Epithelial contact guidance on well-defined micro- and nanostructured substrates
Authors: Teixeira Ana I. , Abrams George A. , Bertics Paul J. , Murphy Christopher J. , Nealey Paul F.
Published: April 2003

The human corneal basement membrane has a rich felt-like surface topography with feature dimensions between 20 nm and 200 nm. On the basis of these findings, we designed lithographically defined substrates to investigate whether nanotopography is a relevant stimulus for human corneal epithelial cells. We found that cells elongated and aligned along patterns of grooves and ridges with feature dimensions as small as 70 nm, whereas on smooth substrates, cells were mostly round. The percentage of aligned cells was constant on substrate tomographies with lateral dimensions ranging from the nano- to the micronscale, and increased with groove depth. The presence of serum in the culture medium resulted in a larger percentage of cells aligning along the topographic patterns than when no serum was added to the basal medium. When present, actin microfilaments and focal adhesions were aligned along the substrate topographies. The width of the focal adhesions was determined by the width of the ridges in the underlying substrate.

This work documents that biologic length-scale topographic features that model features encountered in the native basement membrane can profoundly affect epithelial cell behavior.
Transient association of the sarcoplasmic reticulum Ca2+ATPase with the Na+/K+-ATPase and H+/K+-ATPase β-subunits during its biogenesis in Xenopus oocytes
Authors: Noguchi Shunsuke , Sone Nobuhito , Kawamura Masaru
Published: April 2003

We examined the effect of the β-subunits of the Na+/K+ and H+/K+ ATPases on the biogenesis of the sarcoplasmic reticulum (SR) Ca2+ ATPase in Xenopus oocytes. Oocytes were simultaneously injected with cRNAs for both the SR Ca2+ ATPase and the β-subunit of the Na+/K+ or the H+/K+ ATPase. Immunoprecipitation with antiserum specific for the β-subunit of the Na+/K+ or the H+/K+ ATPase yielded not only the respective β-subunit but also the SR Ca2+ ATPase,indicating that the SR Ca2+ ATPase was associated with theβ-subunits of the Na+/K+ and the H+/K+ ATPases. Pulse-chase experiments revealed that the complex between the SR Ca2+ ATPase and the β-subunit of the Na+/K+ ATPase was formed transiently and dissociated during the course of maturation. This is the first report that demonstrates the association of the SR Ca2+ ATPase with the β-subunit of the Na+/K+ and H+/K+ ATPases.
Bro1 is an endosome-associated protein that functions in the MVB pathway in Saccharomyces cerevisiae
Authors: Odorizzi Greg , Katzmann David J. , Babst Markus , Audhya Anjon , Emr Scott D.
Published: April 2003

Multivesicular bodies are late endosomal compartments containing lumenal vesicles that are formed by inward budding of the limiting endosomal membrane. In the yeast Saccharomyces cerevisiae, integral membrane proteins are sorted into the lumenal vesicles of multivesicular bodies, and this process requires the class E subset of VPS genes. We show that one of the class E VPS genes, BRO1/VPS31, encodes a cytoplasmic protein that associates with endosomal compartments. The dissociation of Bro1 from endosomes requires another class E Vps protein, Vps4, which is an ATPase that also regulates the endosomal dissociation of ESCRT-III, a complex of four class E Vps proteins (Vps2, Vps20, Vps24 and Snf7/Vps32) that oligomerize at the endosomal membrane. We also show that the endosomal association of Bro1 is specifically dependent on one of the ESCRT-III components, Snf7. Our data suggest that the function of Bro1 in the MVB pathway takes place on endosomal membranes and occurs in concert with or downstream of the function of the ESCRT-III complex.
Calmodulin antagonists differentially affect capacitation-associated protein tyrosine phosphorylation of mouse sperm components
Authors: Zeng Hai-Tao , Tulsiani Daulat R. P.
Published: April 2003

Sperm capacitation in vitro is thought to be correlated with the increased protein tyrosine phosphorylation of a subset of sperm components. Our group recently used a pharmacological approach to demonstrate that calmodulin (CaM),a 17 kDa calcium sensor protein, has a role in sperm capacitation. In the present study, we have used several CaM antagonists in an attempt to characterize further the role of CaM in capacitation-associated protein tyrosine phosphorylation of sperm components. Our data demonstrate, first,that mouse spermatozoa incubated in a medium that favors capacitation undergo increased protein tyrosine phosphorylation in a time-dependent manner. Second,inclusion of six CaM antagonists individually in an in vitro incubation medium prevented sperm capacitation, as demonstrated by their diminished ability to undergo agonist-induced acrosome reaction. Third, half of the CaM antagonists(compound 48/80, W13 and CaM-binding domain) had no effect on protein tyrosine phosphorylation or sperm motility. Fourth, by contrast, three CaM antagonists(W7, ophiobolin A and calmidazolium) significantly inhibited protein tyrosine phosphorylation of sperm components (42, 56, 66, 82 and 95 kDa) and adversely affected their motility without altering viability as assessed by propidium iodine staining. Finally, inclusion of purified CaM in the capacitation medium significantly increased tyrosine phosphorylation of 82 kDa and 95 kDa components. Combined, these data suggest that CaM antagonists prevent capacitation by interfering with multiple regulatory pathways, and do so either with or without adverse effects on sperm motility and protein tyrosine phosphorylation.
Agonist-induced endocytosis of lysophosphatidic acid-coupled LPA1/EDG-2 receptors via a dynamin2- and Rab5-dependent pathway
Authors: Murph Mandi M. , Scaccia Launa A. , Volpicelli Laura A. , Radhakrishna Harish
Published: April 2003

Lysophosphatidic acid (LPA) is a serum-borne phospholipid that exerts a pleiotropic range of effects on cells through activation of three closely related G-protein-coupled receptors termed LPA1/EDG-2,LPA2/EDG-4 and LPA3/EDG-7. Of these receptors, the LPA1 receptor is the most widely expressed. In this study, we investigated the agonist-induced endocytosis of the human LPA1receptor, bearing an N-terminal FLAG epitope tag, in stably transfected HeLa cells. Treatment with LPA induced the rapid endocytosis of approximately 40%of surface LPA1 within 15 minutes. Internalization was both dose dependent and LPA specific since neither lysophophatidylcholine nor sphingosine-1-phosphate induced LPA1 endocytosis. Removal of agonist following 30 minutes incubation resulted in recycling of LPA1 back to the cell surface. LPA1 internalization was strongly inhibited by dominant-inhibitory mutants of both dynamin2 (K44A) and Rab5a (S34N). In addition, both dynamin2 K44A and Rab5 S34N mildly inhibited LPA1-dependent activation of serum response factor. Finally, our results also indicate that LPA1 exhibits basal, LPA-dependent internalization in the presence of serum-containing medium.
Cytoplasmic dynein participates in apically targeted stimulated secretory traffic in primary rabbit lacrimal acinar epithelial cells
Authors: Wang Yanru , Jerdeva Galina , Yarber Francie A. , da Costa Silvia R. , Xie Jiansong , Qian Limin , Rose Chadron M. , Mazurek Constance , Kasahara Noriyuki , Mircheff Austin K. , Hamm-Alvarez Sarah F.
Published: April 2003

A major function of the acinar cells of the lacrimal gland is the production and stimulated release of tear proteins into ocular surface fluid. We investigate the participation of cytoplasmic dynein in carbachol-stimulated traffic to the apical plasma membrane in primary rabbit lacrimal acinar epithelial cells. Confocal fluorescence microscopy revealed a major carbachol-induced, microtubule-dependent recruitment of cytoplasmic dynein and the dynactin complex into the subapical region. Colocalization studies,sorbitol density gradient/phase partitioning analysis and microtubule-affinity purification of membranes showed that some dynein and dynactin complex were associated with VAMP2-enriched membranes. Adenovirus-mediated overexpression of p50/dynamitin inhibited the recruitment and colocalization of dynein, the dynactin complex and VAMP2 in the subapical region. Nocodazole treatment and p50/dynamitin overexpression also depleted subapical stores of rab3D in resting acini, suggesting that dynein activity was also involved in maintenance of rab3D-enriched secretory vesicles. These data implicate cytoplasmic dynein in stimulated traffic to the apical plasma membrane in these secretory epithelial cells.
Rit promotes MEK-independent neurite branching in human neuroblastoma cells
Authors: Hynds DiAnna L. , Spencer Mike L. , Andres Douglas A. , Snow Diane M.
Published: April 2003

Rit, by sequence homology, is a member of the Ras subfamily of small guanine triphosphatases (GTPases). In PC6 cells, Rit signals through pathways both common to and different from those activated by Ras to promote cell survival and neurite outgrowth. However, the specific morphological changes induced by Rit in human cells are not known. Here, we show in a human neuronal model that Rit increases neurite outgrowth and branching through MEK-dependent and MEK-independent signaling mechanisms, respectively. Adenoviral expression of wild-type or constitutively active Rit increased neurite initiation,elongation and branching on endogenous matrix or a purified laminin-1 substratum of SH-SY5Y cells as assessed using image analysis. This outgrowth was morphologically distinct from that promoted by constitutively active Ras or Raf (evidenced by increased branching and elongation). Constitutively active Rit increased phosphorylation of ERK 1/2, but not Akt, and the MEK inhibitor PD 098059 blocked constitutively active Rit-induced neurite initiation but not elongation or branching. These results suggest that Rit plays a key role in human neuronal development and regeneration through activating both known and as yet undefined signaling pathways.
Sorting nexin 4 and amphiphysin 2, a new partnership between endocytosis and intracellular trafficking
Authors: Leprince Corinne , Le Scolan Erwan , Meunier Brigitte , Fraisier Vincent , Brandon Nathalie , De Gunzburg Jean , Camonis Jacques
Published: April 2003

Endocytosis is a regulated physiological process by which membrane receptors and their extracellular ligands are internalized. After internalization, they enter the endosomal trafficking pathway for sorting and processing. Amphiphysins consist of a family of proteins conserved throughout evolution that are crucial elements of the endocytosis machinery in mammalian cells. They act as adaptors for a series of proteins important for the endocytic process, such as dynamin. In order to improve our knowledge of amphiphysin function, we performed a two-hybrid screen with the N-terminal part of murine amphiphysin 2 (residues 1-304). One of the interacting clones corresponded to sorting nexin 4 (SNX4), a member of the SNX family of proteins which are suspected to regulate vesicular trafficking. This interaction was confirmed in vivo by co-immunoprecipitation. Immunofluorescence analysis revealed that amphiphysin 2 might bind reticulo-vesicular structures present throughout the cell body and be associated with SNX4 on these structures. In an endocytosis assay, overexpressed C-terminal or full-length SNX4 was able to inhibit transferrin receptor endocytosis as efficiently as the SH3 domain of amphiphysin 2. At lower levels of expression, SNX4 colocalized with transferrin-containing vesicles, some of which were also positive for amphiphysin 2. These results indicate that SNX4 may be part of the endocytic machinery or, alternatively, that SNX4 may associate with key elements of endocytosis such as amphiphysin 2 and sequester them when overexpressed. The presence of amphiphysin 2 on intracellular vesicles and its interplay with SNX4, which is likely to take part in intracellular trafficking, suggest that amphiphysin 2 is not only a regulator of the early steps of endocytosis. It could also play a role at the surface of the endocytic vesicle that has just been formed and of the future endosomes, in order to regulate intracellular trafficking.
TSG-6: a multifunctional protein associated with inflammation
Authors: Milner Caroline M. , Day Anthony J.
Published: April 2003

TSG-6 expression is upregulated in many cell types in response to a variety of proinflammatory mediators and growth factors. This protein is detected in several inflammatory disease states (e.g. rheumatoid arthritis) and in the context of inflammation-like processes, such as ovulation, and is often associated with extracellular matrix remodelling. TSG-6 has anti-inflammatory and chondroprotective effects in various models of inflammation and arthritis,which suggest that it is a component of a negative feedback loop capable of downregulating the inflammatory response. Growing evidence also indicates that TSG-6 acts as a crucial factor in ovulation by influencing the expansion of the hyaluronan-rich cumulus extracellular matrix in the preovulatory follicle. TSG-6 is a member of the Link module superfamily and binds to hyaluronan (a vital component of extracellular matrix), as well as other glycosaminoglycans,via its Link module. In addition, TSG-6 forms both covalent and non-covalent complexes with inter-α-inhibitor (a serine protease inhibitor present at high levels in serum) and potentiates its anti-plasmin activity.
Identification of SAP97 as an intracellular binding partner of TACE
Authors: Peiretti Franck , Deprez-Beauclair Paule , Bonardo Bernadette , Aubert Hélène , Juhan-Vague Irène , Nalbone Gilles
Published: April 2003

Tumor necrosis factor alpha converting enzyme (TACE) is the metalloprotease-disintegrin responsible for the ectodomain shedding of several proteins, including tumor necrosis factor α. Using the yeast two-hybrid system, we identified the scaffolding protein synapse associated protein 97(SAP97) as a binding partner of the cytoplasmic domain of TACE. By deletions and site-directed mutagenesis, we demonstrated that this interaction involved the PDZ3 domain of SAP97 and the extreme C-terminal amino-acid sequence of TACE. This interaction as well as the identification of the specific domains involved was confirmed in vitro by affinity purification and in mammalian cells by co-immunoprecipitation and alteration of localization analyzed by immunofluorescence microscopy. In addition, confocal microscopy showed that endogenous TACE and SAP97 colocalized in some intracellular areas of COS-7 cells and CACO-2 cells. Furthermore, overexpression of SAP97, unlike that of a mutant form of SAP97 deleted for its PDZ3 domain, altered the ability of TACE to release its substrates. Altogether, these results demonstrate an interaction between TACE and SAP97, which may have a functional implication for the regulation of TACE shedding activity.
Macroscopic cartilage formation with embryonic stem-cell-derived mesodermal progenitor cells
Authors: Nakayama Naoki , Duryea Diane , Manoukian Raffi , Chow Gwyneth , Han Chun-ya E.
Published: April 2003

The totipotent embryonic stem cell generates various mesodermal cells when stimulated with BMP4. Among the resulting cells, those expressing flk-1 and/or PDGFRα displayed chondrogenic activity in the presence of TGFβ3 and expressed cartilage-specific genes in 7 to 16 day pellet cultures. Depositions of cartilage matrix and type II collagen were detected by day 14. TGFβ-stimulated chondrogenesis was synergistically enhanced by PDGF-BB,resulting in a larger cartilage particle filled with a cartilaginous area containing type II collagen, with a surface cell layer expressing type I collagen. In contrast, noggin inhibited both the TGFβ- and TGFβ+PDGF-stimulated cartilage formation, suggesting that a BMP-dependent pathway is involved. In fact, replacement of TGFβ3 with BMP4 on days 10 to 12 markedly elevated the cartilage matrix deposition during the following 7 to 8 days. Moreover, culture with TGFβ3 and PDGF-BB, followed by the incubation with BMP4 alone, resulted in a cartilage particle lacking type I collagen in the matrix and the surface layer, which suggests hyaline cartilage formation. Furthermore, such hyaline cartilage particles were mineralized. These studies indicate that the PDGFRα+ and/or flk-1+ cells derived from embryonic stem cells possess the full developmental potential toward chondrocytes, in common with embryonic mesenchymal cells.
Apoptotic insults impair Na+, K+-ATPase activity as a mechanism of neuronal death mediated by concurrent ATP deficiency and oxidant stress
Authors: Wang Xue Qing , Xiao Ai Ying , Sheline Christian , Hyrc Krzystztof , Yang Aizhen , Goldberg Mark P. , Choi Dennis W. , Ping Yu Shan
Published: April 2003

The Na+, K+-ATPase (Na+,K+-pump) plays critical roles in maintaining ion homeostasis. Blocking the Na+, K+-pump may lead to apoptosis. By contrast, whether an apoptotic insult may affect the Na+,K+-pump activity is largely undefined. In cultured cortical neurons, the Na+, K+-pump activity measured as a membrane current Ipump was time-dependently suppressed by apoptotic insults including serum deprivation, staurosporine, and C2-ceramide, concomitant with depletion of intracellular ATP and production of reactive oxygen species. Signifying a putative relationship among these events, Ipump was highly sensitive to changes in ATP and reactive oxygen species levels. Moreover, the apoptosis-associated Na+, K+-pump failure and serum deprivation-induced neuronal death were antagonized by pyruvate and succinate in ATP- and reactive-oxygen-species-dependent manners. We suggest that failure of the Na+, K+-pump as a result of a combination of energy deficiency and production of reactive oxygen species is a common event in the apoptotic cascade; preserving the pump activity provides a neuroprotective strategy in certain pathological conditions.
Specific requirement for two ADF/cofilin isoforms in distinct actin-dependent processes inCaenorhabditis elegans
Authors: Ono Kanako , Parast Mana , Alberico Christine , Benian Guy M. , Ono Shoichiro
Published: April 2003

Actin depolymerizing factor (ADF)/cofilin is an essential enhancer of actin turnover. Multicellular organisms express multiple ADF/cofilin isoforms in different patterns of tissue distribution. However, the functional significance of different ADF/cofilin isoforms is not understood. The Caenorhabditis elegans unc-60 gene generates two ADF/cofilins,UNC-60A and UNC-60B, by alternative splicing. These two ADF/cofilin proteins have different effects on actin dynamics in vitro, but their functional difference in vivo remains unclear. Here, we demonstrate that the two isoforms are expressed in different tissues and are required for distinct morphogenetic processes. UNC-60A was ubiquitously expressed in most embryonic cells and enriched in adult gonads, intestine and oocytes. In contrast, UNC-60B was specifically expressed in the body wall muscle, vulva and spermatheca. RNA interference of UNC-60A caused embryonic lethality with variable defects in cytokinesis and developmental patterning. In severely affected embryos, a cleavage furrow was formed and progressed but reversed before completion of the cleavage. Also, in some affected embryos, positioning of the blastomeres became abnormal, which resulted in embryonic arrest. In contrast, an unc-60B-null mutant was homozygous viable, underwent normal early embryogenesis and caused disorganization of actin filaments specifically in body wall muscle. These results suggest that the ADF/cofilin isoforms play distinct roles in specific aspects of actin reorganization in vivo.
Spatial and temporal dynamics of budding yeast mitochondria lacking the division component Fis1p
Authors: Jakobs Stefan , Martini Nadia , Schauss Astrid C. , Egner Alexander , Westermann Benedikt , Hell Stefan W.
Published: April 2003

The mitochondrial compartment of budding yeast (Saccharomyces cerevisiae) is a highly dynamic net-like structure of tubules that constantly undergo fusion and fission. The outer membrane protein Fis1p plays a crucial role in mitochondrial fission. Here we report on the temporal and spatial dynamics of this organelle in wild-type cells and in fis1Δ mutants. Mitochondria of fis1Δ mutants adapt their mitochondrial network to a change in carbon source. We find that the frequencies of apparent matrix separation and fusion events decrease in both wild-type cells and in mutants lacking Fis1p upon glucose repression. Matrix separation could be caused by matrix constriction and does not necessarily require fission of the inner or outer membrane. Double-labelling experiments demonstrated that some of these matrix separations in fis1 mutants are due to genuine tubule fissions, whereas others do not involve fission of the outer membrane. The rates of matrix separation in fis1Δ mutants almost approach those of the wildtype,demonstrating that, although apparently involved in outer membrane fission,Fis1p is not crucial for the separation of the mitochondrial matrix. In mutants lacking the GTPase Dnm1p no complete tubule fissions were recorded,although dnm1Δ mutants display matrix separations as well. The data suggest that different molecular machineries are responsible for the separation of the matrix and the fission of the outer membrane in budding yeast.
Reactive GRASP: An Application to a Matrix Decomposition Problem in TDMA Traffic Assignment
Authors: Prais Marcelo , Ribeiro Celso C.
Published: April 2003

A greedy randomized adaptive search procedure (GRASP) is a metaheuristic for combinatorial optimization. In this paper, we describe a GRASP for a matrix decomposition problem arising in the context of traffic assignment in communication satellites. We review basic concepts of GRASP: construction and local search algorithms. The local search phase is based on the use of a new type of neighborhood defined by constructive and destructive moves. The implementation of a GRASP for the matrix decomposition problem is described in detail. Extensive computational experiments on literature and randomly generated problems are reported. Moreover, we propose a new procedure Reactive GRASP, in which the basic parameter that defines the restrictiveness of the candidate list during the construction phase is self-adjusted according to the quality of the solutions previously found. The approach is robust and does not require calibration efforts. On most of the literature problems considered, the new Reactive GRASP heuristic matches the optimal solution found by an exact column-generation with branch-and-bound algorithm.
Market Split and Basis Reduction: Towards a Solution of the Cornuéjols-Dawande Instances
Authors: Aardal K. , Bixby R. E. , Hurkens C. A. J. , Lenstra A. K. , Smeltink J. W.
Published: April 2003

At the IPCO VI conference Cornuéjols and Dawande proposed a set of 0-1 linear programming instances that proved to be very hard to solve by traditional methods, and in particular by linear programming-based branch-and-bound. They offered these market split instances as a challenge to the integer programming community. The market split problem can be formulated as a system of linear diophantine equations in 0-1 variables. In our study we use the algorithm of Aardal, Hurkens, and Lenstra (1998) based on lattice basis reduction. This algorithm is not restricted to deal with market split instances only but is a general method for solving systems of linear diophantine equations with bounds on the variables. We show computational results from solving both feasibility and optimization versions of the market split instances with up to 7 equations and 60 variables and discuss various branching strategies and their effect on the number of enumerated nodes. To our knowledge, the largest feasibility and optimization instances solved before had 6 equations and 50 variables, and 4 equations and 30 variables, respectively. We also present a probabilistic analysis describing how to compute the probability of generating infeasible market split instances. By generating instances the way prescribed by Cornuéjols and Dawande, one obtains relatively many feasible instances for sizes larger than 5 equations and 40 variables.
Complexity of Memory-Efficient Kronecker Operations with Applications to the Solution of Markov Models
Authors: Buchholz Peter , Ciardo Gianfranco , Donatelli Susanna , Kemper Peter
Published: April 2003

We present new algorithms for the solution of large structured Markov models whose infinitesimal generator can be expressed as a Kronecker expression of sparse matrices. We then compare them with the shuffle-based method commonly used in this context and show how our new algorithms can be advantageous in dealing with very sparse matrices and in supporting both Jacobi-style and Gauss-Seidel-style methods with appropriate multiplication algorithms. Our main contribution is to show how solution algorithms based on Kronecker expression can be modified to consider probability vectors of size equal to the “actual” state space instead of the “potential” state space, thus providing space and time savings. The complexity of our algorithms is compared under different sparsity assumptions. A nontrivial example is studied to illustrate the complexity of the implemented algorithms.
A Simplex-Based Tabu Search Method for Capacitated Network Design
Authors: Crainic Teodor Gabriel , Gendreau Michel , Farvolden Judith M.
Published: April 2003

The fixed charge capacitated multicommodity network design problem is a well-known problem, of both practical and theoretical significance. This paper presents an efficient procedure to determine tight upper bounds on the optimal solution of realistically sized problem instances. Feasible solutions are obtained by using a tabu search framework that explores the space of the continuous flow variables by combining pivot moves with column generation, while evaluating the actual mixed integer objective. Computational experiments on a large set of randomly generated test problems show that this procedure outperforms the other available methods and is particularly suited to large problem instances with many commodities.
An Ant Colony System Hybridized with a New Local Search for the Sequential Ordering Problem
Authors: Gambardella Luca Maria , Dorigo Marco
Published: April 2003

We present a new local optimizer called SOP-3-exchange for the sequential ordering problem that extends a local search for the traveling salesman problem to handle multiple constraints directly without increasing computational complexity. An algorithm that combines the SOP-3-exchange with an Ant Colony Optimization algorithm is described, and we present experimental evidence that the resulting algorithm is more effective than existing methods for the problem. The best-known results for many of a standard test set of 22 problems are improved using the SOP-3-exchange with our Ant Colony Optimization algorithm or in combination with the MPO/AI algorithm (Chen and Smith 1996).
A Crystal-Chemical Study of Natural and Synthetic Anionic Clays
Authors: de la Calle Cristina , Pons Charles-Henri , Roux Jacques , Rives Vicente
Published: April 2003

A comparative crystallochemical study was performed on natural and synthetic hydrotalcite-like compounds with similar compositions. The nature of the brucite-like sheet stacking was addressed by means of powder X-ray diffraction. From the resulting electron diffraction patterns it was possible to establish the order-disorder of the cations in the brucite-like sheet. The results show that a natural sample from Snarum is an intergrowth of hydrotalcite (3R1 polytype) and manasseite (2H1 polytype) at a ratio of 77:23 (wt.%). An aluminian serpentine is associated with the hydrotalcite and manasseite minerals. The structure of a synthetic sample, Mg:Al = 2:1, was determined as space group <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:c="http://cambridge.org/core/content" xmlns:core="http://cambridge.org/core" xmlns:m="http://cambridge.org/core/metadata" xmlns:cup="http://contentservices.cambridge.org" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest">R3¯m. For a few crystals in this sample, the octahedral cation distribution is compatible with the observed supercell (a = a′ √3). A second synthetic sample showed the presence of stacking faults and was described as a random layer sequence of two polytypes (3R and 2H).
Acid Dissolution of Reduced-Charge Li- and Ni-Montmorillonites
Authors: Pálková Helena , Madejová Jana , Righi Dominique
Published: April 2003

Reduced-charge samples were prepared from Li+- and Ni2+-saturated SAz-1 montmorillonite by heating at 150 and 300°C for 24 h. X-ray diffraction analysis showed interstratification of non-swelling and swelling interlayers in LiS150, while fully expandable interlayers were found in NiS150. Heating at 300°C caused collapse of the interlayers in LiS300 in contrast to NiS300, for which some expandable layers were interstratified in the pseudo-pyrophyllite structure. The infrared (IR) spectra of heated Li-SAz showed new OH-stretching and overtone bands near 3670 cm−1 and 7170 cm−1 (1395 nm), respectively, indicating creation of local trioctahedral domains containing Li(I) in the previously vacant octahedra. No evidence of OH groups in trioctahedral coordination was found in the spectra of heated Ni-SAz. Nickel is supposed to be trapped in the hexagonal holes of the tetrahedral sheets. Reduction of the layer charge substantially affected the extent of the dissolution of SAz-1 montmorillonite in HCl. The MIR and NIR spectra of unheated Li- and Ni-SAz showed a substantial degradation of their structure after acid dissolution. New bands observed at 3744 cm−1 and 7314 cm−1 (1367 nm) were assigned to the vibrations of Si-OH groups formed upon acid treatment. These bands are a means of checking the extent of acid attack on smectites, even in cases when no differences are observed in the 1300−400 cm−1 spectral region (traditionally used to monitor this process). Both the IR spectra and solution analysis revealed that development of non-swelling interlayers in heated montmorillonites substantially reduced dissolution of these samples. The results obtained confirmed that acid attack of the smectite structure occurred at both interlayer surfaces and edges. If the accessibility of the layers for protons is low due to non-swelling interlayers, the dissolution was slower and took place mainly from the particle edges.
Adsorption of Two Quinolinecarboxylic Acid Herbicides on Homoionic Montmorillonites
Authors: Pusino Alba , Gelsomino Antonio , Fiori Maria G. , Gessa Carlo
Published: April 2003

The adsorption of the herbicides quinmerac 7-chloro-3-methylquinoline-8-carboxylic acid (QMe) and quinclorac 3,7-dichloroquinoline-8-carboxylic acid (QCl) on homoionic Fe3+-, Al3+-, Cu2+-, Ca2+-, K+- and Na+-exchanged montmorillonite was studied in aqueous solution. Adsorption data were fitted to the logarithmic form of the Freundlich equation. Ca- and Na-exchanged montmorillonites were ineffective in the adsorption of QMe. On the other hand, the QMe adsorption on Fe-exchanged montmorillonite was rapid and the equilibrium was attained after 15 min. An H-type isotherm was observed for the QMe adsorption on Fe-clay, indicating a high affinity of the solute for the sorption sites and almost complete adsorption from dilute solution. On the other hand, the adsorption isotherm of QMe on Al- and K-clay was of the S-type. This shape suggests that the solvent molecules may compete for the sorption sites. A Fourier transform infrared (FTIR) study suggested that the adsorption mechanism of QMe on Fe-, Al- and K-clay involves the protonation of QMe molecule due to the acidic water surrounding the saturating cations. The greater acidity of Fe-clay compared with Al- and K-clay explains both the lower QMe adsorption observed on Al and K systems and the lack of adsorption on Na and Ca systems. In contrast, the formation of a Cu complex permitted QMe to be adsorbed to a large extent to Cu-clay as shown by FTIR analysis. The QCl was adsorbed only by Fe-clay and the adsorption isotherm of QCl on Fe clay was of the S-type. This finding is consistent with the lower basic character of the QCl molecule nitrogen. In fact, the replacement of the electron-releasing methyl group in QMe with an electron-withdrawing Cl atom to form QCl makes the nitrogen lone-pair electrons of the quinoline ring unavailable for either protonation or complexation.
Intercalation and Surface Modification of Smectite by Two Non-Ionic Surfactants
Authors: Deng Youjun , Dixon Joe B. , White G. Norman
Published: April 2003

Non-ionic surfactants Brij 56 and Igepal CO 720, containing hydrophilic poly(ethylene oxide) (PEO) segments, expanded smectite from 1.5 nm to 1.7 nm at room temperature. The surfactant-smectite composites had larger layer spacings than Ca-smectite after heat treatment. The surfactant-smectite composites were solvated and expanded to 1.8–1.9 nm by polar solvents, glycerol and water, but were not affected by the non-polar or weakly polar solvents, toluene, hexane or octanol. The hydrophilic PEO segments of non-ionic surfactants would logically access the interlayer spaces of smectite whereas the hydrophobic segments extend away from the mineral. The molecular structure and solvation properties suggest that the surfactant molecules are probably concentrated in the margin area of the interlayer galleries forming an annular ring structure between two neighboring silicate sheets. Only two layers or less of the surfactants could access the interlayer galleries of smectite and layer spacings did not exceed 1.8 nm even where excess surfactant was introduced into the composites. The layer spacings of the surfactant-smectite composites were well preserved during water or electrolyte solution washings, indicating stability of most non-ionic surfactant molecules in the interlayer galleries even though ∼30% of the adsorbed Igepal CO 720 was desorbed by exhaustive washing. The non-ionic surfactant treatment preserved >80% of the CEC of the smectite. The interlayer cations of the resulting surfactant-smectite were exchangeable as in the untreated smectite. Therefore, the non-ionic surfactant-smectite was much more efficient at removing heavy metal ions than activated carbon or cationic surfactant-treated smectite. The surfactant-smectite composites effectively removed aromatic chlorophenols from a pH 4.9 acetate buffer solution while untreated smectite did not adsorb these molecules. The enhanced adsorption of the aromatic compounds is attributed to the aliphatic segments of the two surfactants.
Differences in Quasicrystals of Smectite-Cationic Surfactant Complexes Due to Head Group Structure
Authors: Imai Yusuke , Nishimura Satoshi , Inukai Yoshinari , Tateyama Hiroshi
Published: April 2003

The organoclay quasicrystals formed by exchange reactions of fluoromagnesian smectite (FMS) and two kinds of cationic surfactants were investigated by X-ray diffraction (XRD) of both aqueous suspensions and dried powders. ζ potential measurements were also carried out. The two cationic surfactants employed in this study, dodecyltriphenylphosphonium bromide (C12PBr) and dodecyltrimethylammonium bromide (C12NBr), have the same alkyl chain length but different head group structures. In aqueous suspensions of C12N/FMS, regular stacking with a basal spacing of 2.28 nm was observed within the range 0.4 to 1.0 of the cation exchange capacity (CEC) of the C12N/FMS ratios. The basal spacing was constant in this range. The most intense diffraction for the C12N/FMS suspension was observed at 0.6 CEC, and a further increase in the C12N/FMS ratio resulted in a decline of the diffraction intensity and a slight increase in the peak width. On the other hand, in C12P/FMS suspensions with the surfactant/FMS ratios <0.6 CEC, only weak, broad XRD peaks were observed. With higher C12P/FMS ratios (0.8 and 1.0 CEC), strong diffraction peaks appeared with a basal spacing of 3.20 nm. The difference in the observed basal spacings of C12N/FMS and C12P/FMS tactoids was ∼0.9 nm, which did not agree with the difference in the estimated height of the two surfactants (∼0.1 nm). These differences of the tactoid structures between C12N/FMS and C12P/FMS suspensions could be explained in terms of the difference in the adsorption manner of the surfactants on the silicate surface and in the size of the surfactant head groups.
Al-Pillaring of Saponite with the Al Polycation [Al13(OH)24 (H2O)24]15+ Using a New Synthetic Route
Authors: Vicente Miguel Angel , Lambert Jean-François
Published: April 2003

The intercalation of a saponite with the Al polycation [Al13(OH)24(H2O)24]15+ is described. This polycation is obtained by reaction of alumina with Al chloride. The intercalation is achieved by reaction of very concentrated solutions of this polycation with the clay in powder form. Solids with a basal spacing of 18.9 Å were obtained in this way, stable up to 700°C (17.0 Å). The Langmuir surface area of the intercalated solid was 366 m2/g, and that value decreases to 119, 138 and 125 m2/g for the solids pillared at 500, 600 and 700°C, respectively.