bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscoelasticity in Scarred Rabbit Vocal Folds after Hyaluronan Injection
Authors: Hertegard Stellan , Dahlqvist Ake R , Goodyer Eric , Maurer Frans
Published: August 2004

Problem

Hyaluronan has been shown to improve the viscoelastic properties after injections in normal rabbit vocal folds and in patients with unilateral paresis and vocal fold atrophy. Viscoelasticity is important to the vocal fold vibratory capacity. The aim of the study was to analyze the short‐term viscoelastic properties after the injection of hyaluronan in scarred rabbit vocal folds.

Methods

Vocal folds of New Zealand rabbits were scarred and after 2 months one group received injections with crosslinked hyaluronan and another group was injected with saline. After 2 more months (4 months after scarring) both groups and a third group of control animals with normal vocal folds were euthanized. The larynges were dissected out, 16 vocal folds were frozen in −20 C for viscoelastic measurements, whereas 16 vocal folds were prepared and stained for histological analysis including measurements from digitized slides. Two methods were used for the viscoelastic analysis: (1) analyses were made on intact vocal folds with a linear skin rheometer (LSR) adapted to laryngeal measurements, and (2) the vocal folds were dissected and analyzed in a parallel‐plate rheometer.

Results

Measurements on the digitized slides showed a thickened lamina propria of the scarred samples as compared to the normal vocal folds (P < 0.05). The viscoelastic LSR analysis on intact vocal folds showed a tendency to stiffening of the scarred vocal folds as compared to the normal group (P = 0.05). The parallel plate rheometry on the same samples after dissection showed a decreased dynamic viscocity of the scarred samples injected with hyaluronan (Hylaform) as compared to the normals and to the scarred group that received no hyaluronan (P < 0.01 and P < 0.05, respectively).

Conclusion

Injection of scarred rabbit vocal folds with hyaluronan in the short term rendered improved viscoelastic parameters.

Significance

Hyaluroan may prove useful for treating vocal fold scarring.

Support

None reported.
Treatment of Vocal Fold Scar with an Auto‐Crosslinked Polysaccharide Hyaluronan‐Based Gel
Authors: Rousseau Bernard , Tateya Ichiro , Sohn Jin‐Ho , Welham Nathan V , Ford Charles N , Bless Diane M
Published: August 2004

Problem

To examine the effectiveness of an auto‐crosslinked polysaccharide (ACP) hyaluronan‐based gel for the treatment of acute vocal fold scar in a canine animal model.

Methods

Twelve canine larynges were injured by unilateral stripping of the vocal fold mucosa, from the epithelium down to the thyroarytenoid muscle. Six of these animals were treated with a transcutaneous injection of ACP gel (30 mg) into the thyroarytenoid muscle and remaining lamina propria at the time of injury, and again at 7 and 14 days postoperatively. The remaining animals were treated with an injection of sodium chloride to serve as sham controls. All animals were euthanized 2 months following the initial treatment. Excised larynx experiments were completed to obtain phonation threshold pressure (PTP) and vocal economy an acoustic output cost ratio (OCR), followed by histologic analysis for hyaluronan and collagen between the scarred and control vocal fold.

Results

Dense, thick bundle collagen was observed on the injured side of sham‐treated larynges. Minimal collagen deposition was observed on the injured side of ACP‐treated larynges. PTP was lower and OCR was higher in the ACP‐treated animals.

Conclusion

ACP‐treated larynges revealed greater ease of phonation and better vocal economy than sham‐treated larynges. Collagen deposition was less dense in ACP‐treated larynges. ACP gel provided sufficient bulk to the scarred vocal fold.

Significance

ACP gel may provide a useful bio‐injectable substance for improving rheologic tissue and aerodynamic properties for phonation in the scarred larynx.

Support

None reported.
Unbiased Scarpa's Ganglion Neuronal Count Using Stereology in Ototoxicity
Authors: Ishiyama Akira , Ishiyama Gail , Lopez Ivan , Baloh Robert W , Tang Yong
Published: August 2004

Objectives

To obtain unbiased stereologic estimates of the vestibular ganglion neuronal number from 7 subjects with a history of gentamicin (n = 3) and streptomycin (n = 4) aminoglycoside ototoxicity, and compare the results with those from normative age‐matched controls.

Methods

Specimens from the archival temporal bone collection from subjects with a history of aminoglycoside toxicity were used. Normative age‐matched controls were used. Estimates were obtained using the optical fractionator unbiased stereologic technique. The group means were compared using unpaired, 2‐tailed student t test. Significance was set at 0.05.

Results

The average total number of vestibular ganglion neurons in the aminoglycoside group was 20,733 (CV = 0.073). The average total number of vestibular ganglion neurons in the age‐matched normal subjects was 24,902 (CV = 0.109). The vestibular ganglion neuronal count was significantly reduced in the aminoglycoside group (P = 0.0039).

Conclusion

This study uses an unbiased stereologic technique to demonstrate a significant decline in the number of vestibular ganglion neurons in patients with a documented history of streptomycin and gentamicin ototoxicity. The decline may be secondary to deafferentation or to a direct effect of aminoglycosides on the ganglion.
Radial Artery Graft for Bypass of the Maxillary to Proximal Posterior Cerebral Artery
Authors: Ulku Cagatay Han , Ustun Erkan , Buyukmumcu Mustafa , Cicekcibasy Aynur E , Ziylan Taner
Published: August 2004

Objectives

Patients complaining with vertigo or dizziness, the pathology may be originated from central or peripheric compartment. These cases frequently apply to the Neurology, Neurosurgery, or ENT Clinics. The vertebro‐basilar insufficiency is one of the most common pathologic causes of central vertigo or dizziness. This study aims to examine the use of a radial artery graft for bypass of the maxillary artery (MA) to proximal posterior cerebral artery (PCA) as an alternative to external carotid artery (ECA) to PCA anastomosis used for posterior circulation bypass surgery.

Methods

This method was applied to 5 adult cadaver sides bilaterally. The MA was easily found 1−2 cm beneath to infratemporal crest, after a frontotemporal craniotomy and a zygomatic arch osteotomy. Extradurally 2−3 cm posterolateral to the foramen rotundum, a hole was drilled in the sphenoid bone with a 4−mm tipped drill. After sylvian fissure, interpedincular and ambient cisterns were opened, the P2 segment of the PCA appeared. The graft was passed through the hole and the dura to reach the P2 segment. Before giving the infraorbital artery (IOA) branch, the MA was freed from the surrounding tissue and transsected. The proximal side of the radial artery graft was anastomosed end‐to‐end with MA and distal side end‐to‐side with P2 segment of PCA.

Results

The average diameter of the MA before giving the IOA branch was 2.6 ± 0.3 mm. The average diameter of the P2 was 2.2 ± 0.2 mm. The average length of the graft was 47 ± 5.2 mm.

Conclusion

Since MA to proximal PCA bypass uses a short radial graft and may provide a sufficient blood flow, it can pose a reasonable alternative to ECA to PCA bypass.
Amyloidosis: Uncommon Cause of Dysphonia
Authors: Villagomez Vicente , Santos Felicitos , Santos Ramiro , Trevino Jose L. , Cantu Eduardo
Published: August 2004

Objectives

Case report of 3 cases of laryngeal amyloidosis

Methods

Three cases of localized amyloidosis without systemic disease were identified at Centro Univerisitario de Otorrinolaringologia y Cirugia de Cabeza y Cuello at the Univerisity Hospital in Monterrey Mexico. In each patient the major site of involvement was glottic with small focus in the false vocal folds. Medical workup including full blood count, CSR, urea, electrolytes, ureanalysis, liver function test, chest x‐ray, were performed. Physical examination ruled out systemic disease. Congo red staining confirmed the diagnosis in all surgical specimens.

Results

Localized laryngeal amyloidosis was identified in 3 patients (2 males and 1 female) with ages ranging from 33 to 67 years. The presenting symptoms including hoarsness, throat soreness, voice breaks, and vocal fatigue. The duration of the symptoms before diagnosis varied from 3 to 12 years. Assesstment of the extent of laryngeal spread of disease included CT scan, complete voice analysis, and videolaryngostroboscopy in all patients. Material for biopsy was obtained by direct laryngoscopy, apple‐green birefringence was seen with congo red stain establishing the histological diagnosis. The 3 patients underwent phonomicrosurgery for removal of the amyloid implantation using cold knife excision.

Conclusion

Laryngeal amyloidosis is a rare disease with an 8 in 1,000,000 presentation rate. It is more common in males with 3:1 prevalence in the fifth decade. Once the diagnosis is confirmed by congo red staining, it is important to rule out systemic amyloid involvement. It is not necessary to do invasive approach on localized disease. Cold knife excision is still a good method to remove the deposition.
Laryngeal Assessment in Patients with Rheumatic Disease
Authors: Ramos Hugo VL , Pillon Jackeline , Kosugi Eduardo Macoto , Fujita Reginaldo , Barbosa Luiz Henrique F , Neves Luciano R , Pontes Paulo A L
Published: August 2004

Objectives

Autoimmune diseases can cause laryngeal involvement with a highly variable course ranging from asymptomatic to severe states. Just few cases have been described since 1959, when the first laryngeal manifestation of systemic lupus erithematosus (SLE) was published. The aim of this article is to identify and to describe laryngeal manifestations of autoimmune diseases.

Methods

Transversal study with patients presenting SLE, scleroderma, or undifferentiated connective tissue syndrom (UCTS) at Sao Paulo HospitalUniversidade Federal de Sao Paulo/Escola Paulista de MedicinaSao Paulo, Brazil. These patients underwent otorhinolaryngologic evalution with laryngeal videostroboscopic image.

Results

Twenty‐six patients underwent laryngeal videostroboscopic evaluation. One patient could not support the exam. Eleven of 12 (91.6%) patients with SLE presented edema of interarytenoid tissue. Bamboo nodes, that are yellow transverse submucosal vocal fold deposit lesions, were seen in 03 (25%) patients with SLE. One (8.33%) patient had unilateral sulcus vocalis. All 11 patients with scleroderma presented reflux laryngopharyngitis. Two (18.1%) patients presented dilatation of vocal fold blood vessels and another 2 patients presented vocal fold nodule. Among 3 patients with UCTS, in 2 (66.7%) were seen bamboo nodes and reflux laryngopharyngitis.

Conclusion

Laryngeal manifestations due to autoimmune diseases were seen in 07 (26.9%) of 26 patients. Bamboo nodes were seen in 5 (19.2%) patients. Almost all patients presented reflux laryngopharyngitis.
Role of Cochlear Implantation in Susac's Syndrome
Authors: Connell Sarah S , Brodie Fernando
Published: August 2004

Objectives

Susac's syndrome is characterized by the triad of branched retinal artery occlusions, cochlear microangiopathy, and encephalopathy. The underlying process is thought to be a small vessel vasculitis causing microinfarcts in the retina, cochlea, and brain. The purpose of this report is to present the applicability of cochlear implantation in Susac's syndrome with associated auditory neuropathy and encephalopathy.

Methods

A clinical case review of a 39‐year‐old female with Susac's syndrome is presented. The work‐up and treatment is discussed together with the post‐cochlear implant audiologic assessment. The patient developed bilateral profound sensorineural hearing loss (SNHL), encephalopathy, and retinopathy secondary to Susac's syndrome. After the patient's neurological symptoms stabilized, an otolaryngology consult was obtained. The preoperative audiologic evaluation demonstrated absent ABRs bilaterally and intact OAEs at 2 frequencies in one ear suggesting mixed cochlear damage with additional auditory neuropathy.

Results

Despite the confounding features of residual cognitive deficit and auditory neuropathy, the patient's hearing loss was managed successfully with cochlear implantation. After 6 months with her cochlear implant, the patient had markedly improved hearing in noise testing from 0% to 94% correct and word recognition from 0% to 76% at 60 dB.

Conclusion

Susac's syndrome is a rare disorder resulting in SNHL, blindness, and encephalopathy. Early angiography to identify branched retinal artery occlusion lends a clue to the diagnosis. Immunosuppressant therapy is necessary to minimize progression of the disease. Cochlear implantation is a viable option for those patients who develop profound sensorineural hearing loss, even with evidence of auditory neuropathy and limited cognitive deficits.
Use of Elastin Patch for Repair of Traumatic Tympanic Membrane Perforation in Chinchillas
Authors: Kim Sam , Esquivel Carlos R , Grafenberg Matthew Ryan
Published: August 2004

Objectives

Complications from tympanic membrane perforations range from no symptoms to hearing loss and vertigo. Though different grafting materials have been advocated for surgical repair, the healing time has remained constant. We propose the use of elastin (Oregon Medical Laser Center, Portland, OR) as a grafting material for the repair of traumatic tympanic membrane perforations. Furthermore, utilizing laser albumin soldering (Oregon Medical Laser Center, Portland, OR) in the repair allows exploration of possible immediate functional integrity.

Methods

The protocol used 17 animals (Chinchilla laniger). Three groups were studied: (1) repair with elastin alone, (2) repair with elastin and laser albumin solder and (3) repair with paper patch. Traumatic perforations were made bilaterally in each animal. One side served as the repair group, the other as the control. Tympanograms were used to determine functional integrity immediately following the repair and at the end of 5 weeks. The tympanic membranes were then harvested for histological study.

Results

Of all groups (including controls), only 1 animal showed immediate functional integrity (elastin with laser solder). The delayed tympanograms were more varied. The elastin with and without laser soldering groups had identical results (5 of 6), and compared to their respective controls (2 of 6), showed higher incidence of functional integrity. The paper patch group had similar rates (2 of 5) of integrity compared to their controls (3 of 5).

Conclusion

Although the results of immediate elastin repair with and without laser albumin soldering were not superior to the matched controls, the delayed results show promise for accelerated healing.
Intralesional Cidofovir in Laryngeal Papillomatosis
Authors: Horcasitas Ramon A
Published: August 2004

Objectives

The goal of this study is to determine if the use of Cidofovir injected locally reduces the number of debulking procedures on pediatric patients with recurrente respiratory papillomatosis.

Methods

We injected 37.5 mg of Cidofovir intralesionaly in each patient with a laryngeal gauze 27, each 3 weeks for a total of 5 times on each patients. In each patients Hematic count, Hepatic enzymes, and BUN in each patient was done 1 week after and 1 week before each injection.

Results

We included 7 patients in a 18‐month period, 6 of the 7 patients have not needed a debulking procedure in the last 10 months, the obstruction and voice improved, 1 of the patients needed 3 more injections, and has not needed another debulking procedure in the last 3 months; none of the patients had any laboratory alteration.

Conclusion

Cidofovir is a drug effective in the treatment of recurrent respiratory papillomatosis, probably reducing the papilomatosis activity in the laringeal tissue.
Tissue Eosinophilia in Chronic Sinusitis
Authors: Yildirim Altan
Published: August 2004

Objectives

To analyze histopathologically mucosal inflammation and tissue eosinophilia of the osteomeatal complex of the patients with chronic rhinosinusitis and to assess these findings in relation to CT scores.

Methods

The mucosa of the osteomeatal complex of 31 consecutive patients obtained during endoscopic sinus surgery were stained by hematoxylin and eosin. Total inflammatory cells and eosinophils were quantified. The preoperaative CT scans were scored by staging system of LundMacKay.

Results

We have found a significant correlation between the tissue eosinophilia and the total inflammatory cells count of tissue (r = 0.36; P = 0.041). But there were no significant correlation either between the tissue eosinophilia and CT scores (r = 0.34; P = 0.058) or between the total inflammatory cells count of tissue and CT scores (r = 0.10; P = 0.564).

Conclusion

Eosinophilic infiltration seems to be the denominator in chronic rhinosinusitis. But CT findings did not correlated with the extent of mucosal inflammation or with the eosinophilic infiltration.
Postoperative Mucocele in a Pediatric Patient
Authors: Tiu Jeremy Jonathan , Ramadan Hassan H
Published: August 2004

Objectives

Postoperative mucocele formation is a known and late complication of endoscopic sinus surgery in adults. Occurrence in the pediatric population, however, is rare and not reported in the American literature. We report a case of a mucocele in a child after endoscopic sinus surgery.

Methods

A 9‐year‐old female presented with a 1‐month history of proptosis. She denied any headache, eye pain, visual disturbance, nasal obstruction, or rhinorrhea. A CT scan of the orbits revealed a 2.1 ± 1.7 cm expansile soft tissue mass within the left anterior ethmoid air cells, with displacement and thinning of the lamina papyracea. She had a history of endoscopic sinus surgery 3 1/2 years ago.

Results

She underwent endoscopic exam under general anesthesia and a large mucopyocele was identified, involving the ethmoid sinus and left medial orbital wall. The lamina papyracea was eroded. Endoscopically the mucopyocele was removed. The patient did well postoperatively. At 3 weeks follow‐up, her proptosis was improved and there was no evidence of synechia.

Conclusion

Pediatric mucoceles of the paranasal sinuses are a rare entity with little reported in the literature. Furthermore, there are no studies in the American literature describing postendoscopic sinus surgery mucoceles in children. With the increasing numbers of pediatric endoscopic sinus procedures, there needs to be an awareness of this entity as a long‐term postoperative complication. Treatment of mucoceles in children has been described, and like adults, endoscopic drainage is recommended.
Hydrological responses induced by the Tokachi‐oki earthquake in 2003 at hot spring wells in Hokkaido, Japan
Authors: Akita Fujio , Matsumoto Norio
Published: August 2004

Thirty hydrological responses induced by the M8.0 Tokachi‐oki earthquake in 2003 were observed at hot spring wells and an undersea coal mine in Hokkaido, Japan. Most of the decreases and increases in groundwater levels or discharge rates can be explained as a poroelastic response to earthquake‐induced volumetric strain inferred from a fault model determined by dense static GPS observation. In five wells, observed groundwater‐level changes and inferred volumetric strain steps induced by the Tokachi‐oki earthquake are consistent with groundwater‐level changes that are proportional to the inferred volumetric strain steps induced by four large earthquakes in 1993–1994.
Grain‐scale processes during isothermal‐isobaric melting of lherzolite
Authors: Lo Cascio Mauro , Liang Yan , Hess Paul C.
Published: August 2004

The grain‐scale processes of peridotite partial melting were examined at 1340°C and 1.5 GPa using reaction couples formed by juxtaposing pre‐synthesized clinopyroxenite against pre‐synthesized harzburgite. Reaction between clinopyroxenite and harzburgite produces a melt‐enriched, orthopyroxene‐free, olivine + clinopyroxene reactive boundary layer. Clinopyroxene compositions vary systematically across the reactive boundary layer with compositional trends similar to the published clinopyroxene core‐to‐rim compositional variations in the bulk lherzolite partial melting studies conducted at similar P‐T conditions. The growth of the reactive boundary layer is at the expense of the harzburgite and is consistent with grain‐scale processes that involve dissolution, reprecipitation, and diffusive exchange between the interstitial melt and surrounding crystals.
Noradrenaline represses PPAR (peroxisome-proliferator-activated receptor) γ2 gene expression in brown adipocytes: intracellular signalling and effects on PPARγ2 and PPARγ1 protein levels
Authors: LINDGREN Eva M. , NIELSEN Ronni , PETROVIC Natasa , JACOBSSON Anders , MANDRUP Susanne , CANNON Barbara , NEDERGAARD Jan
Published: August 2004

PPAR (peroxisome-proliferator-activated receptor) γ is expressed in brown and white adipose tissues and is involved in the control of differentiation and proliferation. Noradrenaline stimulates brown pre-adipocyte proliferation and brown adipocyte differentiation. The aim of the present study was thus to investigate the influence of noradrenaline on PPARγ gene expression in brown adipocytes. In primary cultures of brown adipocytes, PPARγ2 mRNA levels were 20-fold higher than PPARγ1 mRNA levels. PPARγ expression occurred during both the proliferation and the differentiation phases, with the highest mRNA levels being found at the time of transition between the phases. PPARγ2 mRNA levels were downregulated by noradrenaline treatment (EC50, 0.1 μM) in both proliferative and differentiating cells, with a lagtime of 1 h and lasting up to 4 h, after which expression gradually recovered. The down-regulation was β-adrenoceptor-induced and intracellularly mediated via cAMP and protein kinase A; the signalling pathway did not involve phosphoinositide 3-kinase, Src, p38 mitogen-activated protein kinase or extracellular-signal-regulated kinases 1 and 2. Treatment of the cells with the protein synthesis inhibitor cycloheximide not only abolished the noradrenaline-induced down-regulation of PPARγ2 mRNA, but also in itself induced PPARγ2 hyperexpression. The down-regulation was probably the result of suppression of transcription. The down-regulation of PPARγ2 mRNA resulted in similar down-regulation of PPARγ2 and phosphoPPARγ2 protein levels. Remarkably, the level of PPARγ1 protein was similar to that of PPARγ2 (despite almost no PPARγ1 mRNA), and the down-regulation by noradrenaline demonstrated similar kinetics to that of PPARγ2; thus PPARγ1 was apparently translated from the PPARγ2 template. It is suggested that β-adrenergic stimulation via cAMP and protein kinase A represses PPARγ gene expression, leading to reduction of PPARγ2 mRNA levels, which is then reflected in down-regulated levels of PPARγ2, phosphoPPARγ2 and PPARγ1.
Transcriptional repression of the CTP:phosphocholine cytidylyltransferase gene by sphingosine
Authors: RYAN Alan J. , FISHER Kurt , THOMAS Christie P. , MALLAMPALLI Rama K.
Published: August 2004

We examined the effects of the bioactive lipid, sphingosine, on the expression of the rate-limiting enzyme involved in surfactant phosphatidylcholine synthesis, CCTα (CTP:phosphocholine cytidylyltransferase α). Sphingosine decreased phosphatidylcholine synthesis by inhibiting CCT activity in primary alveolar type II epithelia. Sphingosine decreased CCTα protein and mRNA levels by approx. 50% compared with control. The bioactive lipid did not alter CCTα mRNA stability, but significantly inhibited its transcriptional rate. In murine lung epithelia, sphingosine selectively reduced CCTα promoter-reporter activity when transfected with a 2 kb CCTα promoter/luciferase gene construct. Sphingosine also decreased transgene expression in murine type II epithelia isolated from CCTα promoter-reporter transgenic mice harbouring this 2 kb proximal 5′-flanking sequence. Deletional analysis revealed that sphingosine responsiveness was mapped to a negative regulatory element contained within 814 bp upstream of the coding region. The results indicate that bioactive sphingolipid metabolites suppress surfactant lipid synthesis by inhibiting gene transcription of a key surfactant biosynthetic enzyme.
Deletion of Ser-171 causes inactivation, proteasome-mediated degradation and complete deficiency of human transaldolase
Authors: GROSSMAN Craig E. , NILAND Brian , STANCATO Christina , VERHOEVEN Nanda M. , van der KNAAP Marjo S. , JAKOBS Cornelis , BROWN Lawrence M. , VAJDA Sandor , BANKI Katalin , PERL Andras
Published: August 2004

Homozygous deletion of three nucleotides coding for Ser-171 (S171) of TAL-H (human transaldolase) has been identified in a female patient with liver cirrhosis. Accumulation of sedoheptulose 7-phosphate raised the possibility of TAL (transaldolase) deficiency in this patient. In the present study, we show that the mutant TAL-H gene was effectively transcribed into mRNA, whereas no expression of the TALΔS171 protein or enzyme activity was detected in TALΔS171 fibroblasts or lymphoblasts. Unlike wild-type TAL-H–GST fusion protein (where GST stands for glutathione S-transferase), TALΔS171–GST was solubilized only in the presence of detergents, suggesting that deletion of Ser-171 caused conformational changes. Recombinant TALΔS171 had no enzymic activity. TALΔS171 was effectively translated in vitro using rabbit reticulocyte lysates, indicating that the absence of TAL-H protein in TALΔS171 fibroblasts and lymphoblasts may be attributed primarily to rapid degradation. Treatment with cell-permeable proteasome inhibitors led to the accumulation of TALΔS171 in whole cell lysates and cytosolic extracts of patient lymphoblasts, suggesting that deletion of Ser-171 led to rapid degradation by the proteasome. Although the TALΔS171 protein became readily detectable in proteasome inhibitor-treated cells, it displayed no appreciable enzymic activity. The results suggest that deletion of Ser-171 leads to inactivation and proteasome-mediated degradation of TAL-H. Since TAL-H is a regulator of apoptosis signal processing, complete deficiency of TAL-H may be relevant for the pathogenesis of liver cirrhosis.
Central core disease mutations R4892W, I4897T and G4898E in the ryanodine receptor isoform 1 reduce the Ca2+ sensitivity and amplitude of Ca2+-dependent Ca2+ release
Authors: DU Guo Guang , KHANNA Vijay K. , GUO Xinghua , MacLENNAN David H.
Published: August 2004

Three CCD (central core disease) mutants, R4892W (Arg4892→Trp), I4897T and G4898E, in the pore region of the skeletal-muscle Ca2+-release channel RyR1 (ryanodine receptor 1) were characterized using a newly developed assay that monitored Ca2+ release in the presence of Ca2+ uptake in microsomes isolated from HEK-293 cells (human embryonic kidney 293 cells), co-expressing each of the three mutants together with SERCA1a (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase 1a). Both Ca2+ sensitivity and peak amplitude of Ca2+ release were either absent from or sharply decreased in homotetrameric mutants. Co-expression of wild-type RyR1 with mutant RyR1 (heterotetrameric mutants) restored Ca2+ sensitivity partially, in the ratio 1:2, or fully, in the ratio 1:1. Peak amplitude was restored only partially in the ratio 1:2 or 1:1. Reduced amplitude was not correlated with maximum Ca2+ loading or the amount of expressed RyR1 protein. High-affinity [3H]ryanodine binding and caffeine-induced Ca2+ release were also absent from the three homotetrameric mutants. These results indicate that decreased Ca2+ sensitivity is one of the serious defects in these three excitation–contraction uncoupling CCD mutations. In CCD skeletal muscles, where a mixture of wild-type and mutant RyR1 is expressed, these defects are expected to decrease Ca2+-induced Ca2+ release, as well as orthograde Ca2+ release, in response to transverse tubular membrane depolarization.
Atrial natriuretic peptide levels in adult patients before and after surgery for correction of atrial septal defects: relationship with atrial arrhythmias
Authors: ERBAY Ali R. , YILMAZ Mehmet B. , BALCI Mustafa , SABAH Irfan
Published: August 2004

In the present study, we have examined whether increased N-ANP (N-terminal pro-ANP) levels before and after surgery in patients with ASD (atrial septal defect) along with echocardiographic findings provide a better insight into the pathophysiology and increased morbidity and mortality following corrective surgery. Eighteen adult ASD patients (>20 years of age; six male and 12 female) with shunts (Qp/Qs≥2, where Qp/Qs is the pulmonary blood flow/systemic blood flow) had complete echocardiographic, clinical and laboratory parameters evaluated before and 6 months after surgery. Eight age- and sex-matched individuals (three male and five female) were enrolled as a control group. Blood samples for N-ANP analysis were obtained in both groups. N-ANP levels in the peripheral blood sample from ASD patients before surgery were significantly higher than those in the control group. In patients with ASD, mean N-ANP levels obtained from the pulmonary artery were significantly higher than that obtained from the peripheral vein. RA (right atrial) area, adjusted for body surface area, and RA long-axis and short-axis measurements were significantly higher in the patient group than the control group. N-ANP was correlated significantly with these parameters. Following corrective surgery, N-ANP values and RA area, RA long-axis and short-axis normalization decreased significantly and were accompanied by a decrease in systolic mean pulmonary artery pressure. N-ANP levels were normalized following septal closure in most patients, except in those with atrial fibrillation attacks following corrective surgery. In conclusion, we have shown correlations among variables indicating changes in the architecture of the right atrium along with temporal changes in ANP providing insights into the pathophysiology of post-operative atrial arrhythmias.
Stability analysis of the flow in a cubical cavity heated from below
Authors: Puigjaner D. , Herrero J. , Giralt Francesc , Simó C.
Published: August 2004

A numerical study of bifurcations and stability of the steady convective flow of air in a cubical enclosure heated from below was carried out using a Galerkin spectral method. The set of basis functions was chosen so that all boundary conditions and the continuity equation were implicitly satisfied. A parameter continuation method was applied to determine the steady solutions and bifurcations of the nonlinear governing equations as a function of Rayleigh number (Ra) for values of Ra up to 1.5×105. The eigenvalue problem associated with the stability analysis of the steady solutions along the different branches of solutions was solved using the Arnoldi method. The convergence of the method was consistent with the number of modes used and the results were also verified by a numerical solution of the unsteady equations of motion using a finite-difference solver. Present results show that different stable convective flow patterns can coexist for different ranges of the Rayleigh number.
Systematic correlation between Raman spectra, photoluminescence intensity, and absorption coefficient of silica layerscontaining Si nanocrystals
Authors: Khriachtchev Leonid , Räsänen Markku , Novikov Sergei , Pavesi Lorenzo
Published: August 2004

The correlation between optical, structural, and light-emitting properties of annealed Si-rich silica samples containing different amounts of Si nanocrystals is studied. The intensity of the 1.6eV emission band weakens when the Raman signal coming from the Si nanocrystals gets stronger. On the contrary, the absorption coefficient follows the increase of the Raman intensity with the Si nanocrystal density. The decrease of the photoluminescence is accompanied with the increase of tensile stress, which is suggested by the Raman spectra. Possible explanations of the observed dependencies are discussed.
Enhancement of the dielectric permittivity of Ta2O5 ceramics by CO2 laser irradiation
Authors: Ji Lingfei , Jiang Yijian , Wang Wei , Yu Zhenlong
Published: August 2004

The tantalum-pentoxide ceramics with significantly enhanced dielectric permittivities around 60–70 (up to 71.62) at 1MHz and 20°C were prepared by CO2 laser irradiation. The dielectric loss and the temperature coefficient of dielectric permittivity could be 0.0128 and 721ppm∕°C, respectively. Dielectric properties were investigated over the temperature range from −60 to 100°C at 1MHz. The frequency dependence of the dielectric properties was also investigated between 1kHz and 1MHz at 20°C. The stabilization of high-temperature phase at RT and crystallographic orientation in the ceramics by laser irradiation can explain the strong enhancement of the dielectric permittivity.
Ferroinductor coupled discharge
Authors: Bliokh Yu. P. , Felsteiner J. , Slutsker Ya. Z. , Vaisberg P. M.
Published: August 2004

An inductively coupled discharge was obtained at low gas pressure. Unlike an ordinary inductively coupled discharge with an inductorlike rf antenna, we used a magnetic core with a primary winding (“ferroinductor”). In this way, we increased the electric field and eliminated the magnetic field of the winding. Gas breakdown was obtained at a pressure as low as 10−4Torr, the discharge plasma ionization rate reached almost 100%, and the maximum plasma density was about 1013cm−3. The high inductance of the ferroinductor allowed us to work even with single pulses. The efficiency of such a discharge as a plasma source could reach 90%, which makes this kind of discharge attractive for many applications.
Tailoring the optical excitation energies of single-walled carbon nanotubes
Authors: Cao Anyuan , Ajayan Pulickel M. , Filin A. , Persans P.
Published: August 2004

Optical absorption of thin-film single-walled carbon nanotubes was investigated. The excitation energies were tailored by controlling the film thickness and the average nanotube diameter. The lowest absorption band (S1, peaked at ∼0.68eV) moves toward higher energy with increasing nanotube film thickness linearly at 5.5meV∕μm, due to the band-gap increase of stretched nanotubes stacked in the film. A subsequent heating of nanotube films at 400°C in air could further shift the S1 band upward for over 35meV. We created a tandem structure by combining multiple nanotube layers with different diameter distributions in order to define a particular excitation energy. Our nanotube thin films are macrodevices with tunable optical properties in optoelectronic and photonic applications.
Synthesis of bulk superhard semiconducting B–C material
Authors: Solozhenko Vladimir L. , Dubrovinskaia Natalia A. , Dubrovinsky Leonid S.
Published: August 2004

A bulk composite superhard material was synthesized from graphitelike BC3 at 20GPa and 2300K using a multianvil press. The material consists of intergrown boron carbide B4C and B-doped diamond with 1.8at.%B. The material exhibits semiconducting behavior and extreme hardness comparable with that of single-crystal diamond.
Highly efficient red electrophosphorescent devices based on an iridium complex with trifluoromethyl-substituted pyrimidine ligand
Authors: Niu Yu-Hua , Chen Baoquan , Liu Sen , Yip Hinlap , Bardecker Julie , Jen Alex K.-Y , Kavitha Jakka , Chi Yun , Shu Ching-Fong , Tseng Ya-Hsien , Chien Chen-Han
Published: August 2004

Highly efficient red-emitting electrophosphorescent devices were fabricated by doping an iridium (Ir) complex containing trifluoromethyl (CF3)-substituted pyrimidine ligand into a conjugated bipolar polyfluorene with triphenylamine and oxadiazole as side chains. The device efficiency can be enhanced through effective exciton confinement using a layer of 1,3,5-tris(N- phenylbenzimidazol-2-yl)benzene on the cathode side and a layer of in situ polymerized tetraphenyldiamine-perfluorocyclobutane on the anode side. For a blend with 5wt% of the Ir complex, a maximum external quantum efficiency of 7.9 photon/electron % and a maximum brightness of 15800cd∕m2 are reached with Commission Internationale de L’Eclairage chromaticity coordinates of x=0.65 and y=0.34.
Calculation of phonon spectra to predict the high-pressure metastable phase in an equilibrium immiscible Cu–Ta system
Authors: Kong Y. , Gong H. R. , Liu B. X.
Published: August 2004

Under the framework of lattice dynamics, the phonon spectra of the possible metastable Cu3Ta compounds at zero pressure are computed based on an n-body potential by fitting to some physical properties acquired from ab initio calculations. For the three ideal lattices, i.e., L12, D03, and D019, imaginary phonons appear along all high symmetry directions in the Brillouin zone and disappear while subjected to high pressure at about 2.7, 11.8, and 14.7GPa, respectively. Interestingly, one of the predicted compounds in an L12 structure has indeed been obtained by ion-beam mixing under an appropriate condition.
Slow-light enhancement of radiation pressure in an omnidirectional-reflector waveguide
Authors: Povinelli M. L. , Ibanescu Mihai , Johnson Steven G. , Joannopoulos J. D.
Published: August 2004

We study the radiation pressure on the surface of a waveguide formed by omnidirectionally reflecting mirrors. In the absence of losses, the pressure goes to infinity as the distance between the mirrors is reduced to the cutoff separation of the waveguide mode. This divergence at constant power input is due to the reduction of the modal group velocity to zero, which results in the magnification of the electromagnetic field. Our structure suggests a promising alternative, microscale system for observing the variety of classical and quantum-optical effects associated with radiation pressure in Fabry–Perot cavities.
Combining large magnetostriction and large magnetostrictive susceptibility in TbFeCo∕YxFe1−x exchange-spring-type multilayers
Authors: Huong Giang D. T. , Duc N. H. , Thuc V. N. , Vu L. V. , Chau N.
Published: August 2004

An approach to obtain both large magnetostriction and large magnetostrictive susceptibility is developed. It is applied to sputtered {Tb(Fe0.55Co0.45)1.5∕(YxFe1−x)} (x=0, 0.1 and 0.2) multilayers. In the as-deposited samples, the TbFeCo layers are in the amorphous state, but the microstructure of the YxFe1−x layers is not the same: A crystalline state is observed in pure Fe layers (x=0), whereas body-centered-cubic-Fe nanocrystals coexist within an YFe amorphous matrix in Y0.1Fe0.9 layers. A parallel magnetostrictive susceptibility χλ‖ as large as 29.4×10−2T−1, which is almost half of that (79.6×10−2T−1) of the Metglas 2605SC was obtained for x=0.1. This is attributed to the exchange coupling between sandwiched TbFeCo layers and nanostructured YFe layers.
Effects of Cu in CdS∕CdTe solar cells studied with patterned doping and spatially resolved luminescence
Authors: Feldman S. D. , Collins R. T. , Kaydanov V. , Ohno T. R.
Published: August 2004

Cd S ∕ Cd Te solar cells were nonuniformly doped at the backsurface of the CdTe with Cu evaporated through a shadow mask. Spatially resolved electroluminescence measurements showed strong correlation of emission intensity with the Cu pattern for all photon energies. Photoluminescence (PL) measurements performed on the exact same region showed no correlation with the Cu pattern when integrated over all energies. However, lower energy PL (located in a broad defect-related band) was slightly more intense in Cu-doped regions, whereas the intensity of PL from shallower states was slightly greater in undoped regions. These small differences in spectra were discernable only with the patterned doping and spatially resolved characterization used here.
Tunable transmission and bistability in left-handed band-gap structures
Authors: Feise Michael W. , Shadrivov Ilya V. , Kivshar Yuri S.
Published: August 2004

We study the defect-induced nonlinear transmission of a periodic structure created by alternating slabs of two materials with positive and negative refractive index. We demonstrate bistable switching and tunable nonlinear transmission in an unconventional band gap that corresponds to the vanishing average refractive index, and compare the observed effects for two different types of band gaps.
Preparation of functional DNA microarrays through laser-induced forward transfer
Authors: Serra P. , Colina M. , Fernández-Pradas J. M. , Sevilla L. , Morenza J. L.
Published: August 2004

A functional DNA microarray was prepared through the laser-induced forward transfer (LIFT) technique. In a first experiment, droplets of a buffer solution were spotted onto a substrate at different laser pulse energies. This allowed one to determine that uniform spots with a diameter as small as 40μm could be obtained. In a second experiment, a microarray containing two different human cDNAs and a negative control was spotted through LIFT and submitted to a hybridization assay. The obtained results demonstrated the full functionality of the microarray, which allowed us to prove the viability of LIFT for the production of DNA microarrays.
Effective mass of InN epilayers
Authors: Fu S. P. , Chen Y. F.
Published: August 2004

We report on the study of plasma edge absorption of InN epilayers with free electron concentration ranging from 3.5×1017to5×1019cm−3. Together with the previously reported data, the wide range variation of effective mass cannot be explained by Kane’s two band k∙p model alone. We show that the combination of Kane’s two band k∙p model, band renormalized effect due to electron–electron interaction, and electron–ionized impurity interaction can provide an excellent description. The effective mass of the free electron at the bottom of the conduction band was found to be m*=0.05m0, which is in good agreement with the very recent theoretical calculation.
Gallium-driven assembly of gold nanowire networks
Authors: Yazdanpanah Mehdi M. , Harfenist Steven A. , Cohn Robert W.
Published: August 2004

Nanowire networks of Au–Ga alloy are fabricated at temperatures between 220 and 300°C by application of small drops of liquid gallium to 10- to 100-nm-thick gold films. As the liquid gallium drop spreads and reacts with the gold film, lamellar segregation of gold-rich and gallium-rich regions form fractal-like networks of Au–Ga nanowires connected between gold-rich islands in specific zones concentric to the gallium droplet. The wires are subsequently suspended by wet chemical etching that undercuts the ∼10-nm-thick chromium adhesion layer and the silicon substrate. Suspended nanowires as long as 6μm and as narrow as 35nm diameter have been produced using this method.
Above room temperature operation of short wavelength (λ=3.8μm) strain-compensated In0.73Ga0.27As–AlAs quantum-cascade lasers
Authors: Semtsiv M. P. , Ziegler M. , Dressler S. , Masselink W. T. , Georgiev N. , Dekorsy T. , Helm M.
Published: August 2004

We demonstrate the design and implementation of a broad-gain and low-threshold (Jth=860A∕cm2 at 8K) quantum-cascade laser emitting between 3.7 and 4.2μm. The active region design is based on strain-compensated In0.73Ga0.27As–AlAs on InP. Laser operation in pulsed mode is achieved up to a temperature of 330K with maximum single-facet output peak powers of 6W at 8K and 240mW at 296K. The temperature coefficient T0 is 119K.
Switching leukemia cell phenotype between life and death
Authors: Tucker Steven J. , Rae Colin , Littlejohn Alison F. , Paul Andrew , MacEwan David J.
Published: August 2004

Divergent life or death responses of a cell can be controlled by a single cytokine (tumor necrosis factor α, TNF) via the signaling pathways that respond to activation of its two receptors (TNFR1 and TNFR2). Here, we show that the choice of life or death can be controlled by manipulation of TNFR signals. In human erythroleukemia patient myeloid progenitor stem cells (TF-1) as well as chronic myelogenous leukemia cells (K562), granulocyte–macrophage colony-stimulating factor primes cells for apoptosis. These death-responsive cells show prolonged TNF stimulation of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase, but no NF-κB transcriptional activity as a consequence of receptor-interacting protein degradation by caspases. Conversely, cells of a proliferative phenotype display antiapoptotic NF-κB responses that antagonize c-Jun N-terminal kinase and p38 mitogen-activated protein kinase stress kinase effects. These proliferative effects of TNF are apparently due to enhanced basal expression of the caspase-8/FLICE-inhibitory protein FLIP. Manipulation of the NF-κB, c-Jun N-terminal kinase, or p38 mitogen-activated protein kinase signals switches leukemia cells from a proliferative to an apoptotic phenotype; consequently, these highly proliferative cells die rapidly. In addition, sodium salicylate mimics the death phenotype signals and causes selective destruction of leukemia cells. These findings reveal the signaling mechanisms underlying the phenomenon of human leukemia cell life/death switching. Additionally, through knowledge of the signals that control TNF life/death switching, we have identified several therapeutic targets for selectively killing these cells.
Biosynthesis of artificial microperoxidases by exploiting the secretion and cytochrome
c
maturation apparatuses of
Escherichia coli
Authors: Braun Martin , Thöny-Meyer Linda
Published: August 2004

Microperoxidases were initially isolated as peptide fragments containing covalently bound heme and are derived from naturally occurring
c
-type cytochromes. They are not only used as model compounds but also have potential applications as biosensors, electron carriers, photoreceptors, microzymes, and drugs. In a systematic attempt to define the minimal requirements for covalent attachment of hemes to
c
-type cytochromes, we have succeeded to produce artificial microperoxidases with peptide sequences that do not occur naturally and can be manipulated. The
in vivo
production of these microperoxidases requires targeting of the peptide to the bacterial periplasm, proteolytic processing of the signal peptide, and covalent attachment of heme to the signature motif CXXCH by the cytochrome
c
maturation proteins CcmA-H. The peptides that bind heme carry a C-terminal histidine tag, presumably to stabilize the heme peptide. We present a heme cassette that is the basis for the
de novo
design of functional hemoproteins.
The learning curve: Implications of a quantitative analysis
Authors: Gallistel Charles R. , Fairhurst Stephen , Balsam Peter
Published: August 2004

The negatively accelerated, gradually increasing learning curve is an artifact of group averaging in several commonly used basic learning paradigms (pigeon autoshaping, delay- and trace-eye-blink conditioning in the rabbit and rat, autoshaped hopper entry in the rat, plus maze performance in the rat, and water maze performance in the mouse). The learning curves for individual subjects show an abrupt, often step-like increase from the untrained level of responding to the level seen in the well trained subject. The rise is at least as abrupt as that commonly seen in psychometric functions in stimulus detection experiments. It may indicate that the appearance of conditioned behavior is mediated by an evidence-based decision process, as in stimulus detection experiments. If the appearance of conditioned behavior is taken instead to reflect the increase in an underlying associative strength, then a negligible portion of the function relating associative strength to amount of experience is behaviorally visible. Consequently, rate of learning cannot be estimated from the group-average curve; the best measure is latency to the onset of responding, determined for each subject individually.