A case of glaucoma associated with Sturge-Weber syndrome and Nevus of Ota

The Sturge-Weber syndrome consists of a unilateral port-wine hemangioma of the skin along the trigeminal distribution and is accompanied by an ipsilateral leptomeningeal angioma. Glaucoma is present in approximately half of the cases. The Nevus of Ota is a melanocytic pigmentary disorder, most commonly involving the area innervated by the trigeminal nerve. Elevated intraocular pressure, with or without glaucomatous damage, is observed in 10% of the cases. We report the first case of glaucoma associated with Sturge-Weber syndrome and Nevus of Ota in Korea.

The effect of intranasal fentanyl on the emergence characteristics after sevoflurane anesthesia in children undergoing surgery for bilateral myringotomy tube placement

Children undergoing placement of bilateral myringotomy tubes (BMT) often exhibit pain-related behavior (agitation) in the postanesthesia care unit. We compared the emergence and recovery profiles of pediatric patients who received sevoflurane with or without supplementary intranasal fentanyl for BMT surgery. By using a prospective, double-blinded design, 150 children 6 mo to 5 yr of age, scheduled for routine BMT surgery, were anesthetized with sevoflurane (2%-3%) in a 60% N(2)O/O(2) gas mixture. Patients were randomized to receive equal volumes of intranasal saline (Control), 1 microg/kg fentanyl or 2 microg/kg fentanyl. A blinded observer evaluated each patient using a previously described 4-point agitation scale and the Steward recovery scale. Response to parental presence was observed after a score of six (full recovery) was achieved on the Steward recovery scale. There were no significant differences among the three groups regarding age, weight, surgeon, duration of anesthesia, or ear condition. Recovery times and emergence characteristic scores were not statistically different. Agitation scores were significantly reduced in the 2-microg/kg Fentanyl group as compared with the Control group (P = 0.012). Fentanyl 2 microg/kg is recommended to reduce the incidence of agitation seen in these patients.

IMPLICATIONS

We examined the use of nasally administered fentanyl for the relief of agitation or discomfort after placement of bilateral myringotomy tubes in 150 children ages 6 mo to 5 yr using a prospective, double-blinded design. Fentanyl 2 microg/kg was found to reduce the incidence of agitation in these patients.

Possible roles of JNK pathway in the regulation of hippocampal proenkephalin and immediate early gene expression induced by kainic acid

Mitogen-activated protein kinases (MAPKs) may play crucial roles in the kainic acid (KA)-evoked excitotoxic effect and the regulation of transcription factors (e.g. c-Fos and c-Jun) in hippocampus, but their exact role in the regulation of KA-induced opioid peptides expression has not been well characterized in vivo. Therefore, we examined possible involvement of the phosphorylated form of JNK, as well as CREB, in the regulation of KA-induced proenkephalin and immediate early genes (IEGs) expression in the rat hippocampus. KA increased proenkephalin mRNA expression in rat hippocampus, which was decreased by pre-administration with cycloheximide (CHX, a protein synthesis inhibitor). KA alone increased c-fos as well as c-jun mRNA levels. CHX further enhanced KA-induced c-fos and c-jun mRNA levels. Additionally, KA increased the phosphorylation of JNK, especially JNK1, which was attenuated by CHX. CHX decreased KA-induced c-Fos protein expression. Interestingly, CHX itself increased the phosphorylation of CREB, which was abolished by KA administration. Our results suggest that the phosphorylation of JNK is involved in the up-regulation of the proenkephalin gene expression via c-Fos and c-Jun that is induced by KA in rat hippocampus. However, the phosphorylation of CREB is not associated with the up-regulation of the proenkephalin mRNA level induced by KA in the rat hippocampus.

Differential roles of spinal cholera toxin- and pertussis toxin-sensitive G proteins in nociceptive responses caused by formalin, capsaicin, and substance P in mice

The aim of the present study is to characterize the roles of spinal cholera toxin (CTX)- and pertussis toxin (PTX)-sensitive G proteins in the regulation of various nociceptive responses. The effects of intrathecal (i.t.) pretreatments with CTX and PTX on the formalin (subcutaneous)-, capsaicin (i.t.)-, and substance P (SP; i.t.)-induced nociceptive behaviours were examined in mice. Pretreatment with CTX (i.t.; 24 h before) significantly and dose-dependently (0.05-0.5 microg) suppressed both the first and second phases of the formalin-induced nociceptive behaviour. On the other hand, pretreatment with PTX (i.t., 6 days before) at the same doses (0.05-N0.5 microg) did not affect the formalin-induced response. Capsaicin (i.t., 0.5 microg)- and SP (i.t., 0.7 microg)-induced nociceptive behaviours were attenuated by the pretreatment with CTX. In addition, SP-induced nociceptive response was also attenuated by the pretreatment with PTX. However, the capsaicin-induced nociceptive response was not influenced by PTX pretreatment. These findings suggest that, at the spinal cord level, CTX-sensitive G-proteins are involved in the formalin-, capsaicin-, and SP-induced nociceptive behavioural responses, whereas PTX-sensitive G proteins are involved in SP-induced nociceptive response.

Production and secretion patterns of cloned glucoamylase in plasmid-harboring and chromosome-integrated recombinant yeasts employing an SUC2 promoter

To understand the differences in production and secretion patterns between plasmid-harboring and chromosome-integrated recombinant yeasts, the two recombinant Saccharomyces cerevisiae yeasts, containing the structural glucoamylase STA gene and the SUC2 promoter, were investigated. Both systems were regulated by glucose concentration in the culture broth. First, the glucoamylase activity per gene copy number of the chromosome-integrated recombinant yeast was 2.8- to 5.6-fold higher than that of the plasmid-harboring recombinant yeast. Overburdened owing to high copy number, the plasmid-harboring recombinant yeast gave lower glucoamylase activity per gene copy number. Second, the efficiency of signal sequence was compared; the secretion efficiency of glucoamylase in the plasmid-harboring recombinant yeast was higher than that in the chromosome-integrated recombinant yeast at 96 h of cultivation (74 vs 65%). We postulated that the higher level of secretion efficiency of the plasmid-harboring recombinant yeast resulted because the production level did not reach the capacity of the secretory apparatus of the host yeast. However, the specific secretion rate was much higher in the chromosome-integrated recombinant yeast even though the final secretion efficiency was lower. The lower secretion rate in the plasmid-harboring recombinant yeast could be explained by an adverse effect caused by higher production rate. Finally, the optimal glucose concentration for glucoamylase production in the chromosome-integrated recombinant yeast culture was lower than that in the plasmid-harboring recombinant yeast culture owing to gene dosage effect.

Purification and characterization of a highly stable tyrosinase from Thermomicrobium roseum

Tyrosinase, with an isoelectric point at pH 4.9, was purified to electrophoretic homogeneity from an extremely thermophilic bacterium, Thermomicrobium roseum. Gel filtration, N-terminal amino acid sequencing and SDS/PAGE analysis indicate that T. roseum tyrosinase is composed of two identical subunits, each with a molecular mass of 43000 Da. The enzyme exhibited high substrate specificity towards catechol, chlorogenic acid, L-3-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA) and pyrogallol. The K(m) value of the enzyme for L-DOPA was 0.18 mM. beta-Mercaptoethanol and sodium diethyldithiocarbamate notably inhibited the enzymic activity. The activity of the enzyme was optimal at pH 9.5 and 70 degrees C, and was increased by addition of 1 mM Mg(2+), K(+) or Cu(2+). The enzyme was highly stable against high temperature and guanidine hydrochloride. The N-terminal amino acid sequence of the enzyme was determined to be Asp-Ile-Asn-Gly-Gly-Gly-Ala-Thr-Leu-Pro-Gln-Lys-Leu-Tyr. These facts indicate that T. roseum tyrosinase appears to be distinct from the tyrosinases so far purified from other sources.

Postsurgical follow-up of children with tympanostomy tubes: results of the American Academy of Otolaryngology-Head and Neck Surgery Pediatric Otolaryngology Committee National Survey

Postsurgical follow-up of children with tympanostomy tubes is becoming a contentious issue in this era of managed care. Primary care providers believe themselves to be capable of evaluating these children. Otolaryngologists, on the other hand, have more specialized equipment available to them (suction apparatus, otomicroscopes, audiology devices, etc) for treating suppurative infections and monitoring the tympanic membrane for structural changes. In addition, the otolaryngologist is placed in an uncomfortable legal and ethical position if access to the patient with a tube-related complication is denied by the primary care provider. Attempts to develop an American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) policy statement have been hampered by a lack of data on the incidence and severity of tube-related complications and the role that otolaryngologists can play in reducing these sequelae. A survey designed by the AAO-HNS Pediatric Otolaryngology Committee was distributed to 1000 board-certified otolaryngologists and all members of the American Society of Pediatric Otolaryngologists and the American Academy of Pediatrics-Otolaryngology Section regarding current practice patterns and practitioners' experiences with tympanostomy tube complications. Specific information regarding complications that could have been avoided with earlier otolaryngology referral was also obtained. The results of the survey and its implications for AAO-HNS policy are presented.

Changing trends in neonatal subglottic stenosis

OBJECTIVES

To determine whether there are any changes in the incidence and management of neonatal subglottic stenosis (SGS).

METHODS

A retrospective chart review of 416 infants who were admitted to the neonatal intensive care unit of the Children's National Medical Center between July 1, 1995, and June 30, 1996, was carried out. The incidence of airway obstruction requiring anterior cricoid split or placement of tracheotomy tube was determined and compared with the incidence studied 10 years ago at the same institution.

RESULTS

One of 416 neonates required surgical intervention for airway obstruction caused by SGS, for an overall neonatal SGS incidence of 0.24%. When only the neonates who were intubated for 48 hours or longer were considered, the incidence of SGS was 0.49% (1/204). In neonates who were intubated for 48 hours or longer and survived, the incidence of SGS was 0.63% (1/160). This is in comparison with the incidences of 0.65% (3/462), 1.5% (3/195), and 1.9% (3/159), respectively, seen in a study done at the Children's National Medical Center 10 years ago. Five infants in this current study required placement of a tracheotomy tube for reasons other than SGS. Two infants needed tracheotomy tube placement for micrognathia, and 3 others for central hypotonia, an omphalocele that required multiple surgical procedures, and choanal atresia with a serious heart anomaly, which was a manifestation of CHARGE association. None of these 5 infants had evidence of SGS at rigid endoscopy preceding the tracheotomy tube placement.

CONCLUSION

The incidence and management of neonatal SGS remain unchanged during this study period when compared with those of 10 years ago.

Airway abnormalities in patients with Arnold-Chiari malformation

OBJECTIVES

The goal was to determine the incidence and types of airway abnormalities in patients with Arnold-Chiari malformation (ACM).

METHODS

The study was a retrospective chart review of 24 patients with ACM who were evaluated and treated between November 1991 and August 1997.

RESULTS

Eighteen (75%) and 6 (25%) of the 24 patients had types I and II ACM, respectively. Three (12.5% of 24 patients) of the type II ACM patients had vocal cord impairment: 1 bilateral paralysis, 1 bilateral paresis, and 1 unilateral paralysis. None of the type I ACM patients had vocal cord impairment. Tracheotomy was necessary in 3 of the 24 patients and all in patients with type II ACM. Central sleep apnea was found in 5 of 6 type II ACM patients, but not in any of the type I ACM patients.

CONCLUSIONS

Vocal cord impairment and sleep apnea were found in 12. 5% and 21%, respectively, of this ACM population. When type II ACM patients were considered separately, the incidences of vocal cord impairment and sleep apnea were 50% and 83%, respectively. Type II ACM patients tend to have a higher incidence of airway abnormalities and other neurologic dysfunctions. Flexible fiberoptic laryngoscopy is recommended in the airway evaluation of ACM patients. Early recognition, diagnosis, and management of these abnormalities may be lifesaving.

Chromosomal localization of ESTs obtained from human fetal liver via BAC-mediated FISH mapping

A total of 55 expressed sequence tags (ESTs) randomly chosen from our collection of fetal liver ESTs were mapped to chromosomes by fluorescence in situ hybridization (FISH) mapping techniques. To generate FISH mapping probes, the genomic DNAs for each EST were selected by screening an arrayed human bacterial artificial chromosome (BAC) library. In total, 73 BACs were used for mapping of the 55 ESTs. Among them, 70 BACs representing 52 ESTs unequivocally mapped to single chromosomal regions. The remaining 3 BACs representing 3 ESTs were localized to multiple regions, suggesting that BACs may have very low chimerism. Our mapping results were compared with EST mapping databases deposited in NCBI. Thirty-six of 55 ESTs corresponded to previously mapped positions of ESTs, 2 ESTs mapped to different positions from previously determined ones, and it was found that 17 ESTs have been mapped on new locations from this study. These mapping data may be used for completing the framework of the human physical map, and also for providing a good starting point for searching disease-related genes.

Pitfalls in laryngotracheal reconstruction

OBJECTIVE

To determine the causes of laryngotracheal reconstruction (LTR) failures.

DESIGN

Retrospective chart review.

SETTING

Tertiary care children's hospital.

PATIENTS

Seventeen pediatric patients who underwent revision LTR from October 1, 1986, to December 31, 1998.

INTERVENTION

Laryngotracheal reconstruction.

MAIN OUTCOME MEASURE

Decannulation.

RESULTS

Seventeen patients required a total of 42 LTRs for decannulation. There were 17 primary LTRs and 25 revision LTRs. The primary LTRs were done either at our or other institutions. Two patients died after initial LTR failed, one because of tracheotomy tube plugging and the other because of a severe respiratory syncytial virus pneumonia. All 15 remaining patients have been decannulated. There were 27 failed LTRs with 17 being primary and 10 revision LTR failures. In 3 of the 27 failed procedures, no obvious causes for failure could be found. In the remaining 24 procedures, 1 or more factors that contributed to LTR failure could be found. Poor preoperative evaluation with subsequent failure to address the airway lesion was seen in 6 procedures. Intraoperative reasons for LTR failure included inappropriate choice of graft in 2 procedures; inappropriate stent in 7; inappropriate stent length in 1; and inappropriate duration of stent in 8. In 6 procedures, the airway abnormalities identified at endoscopy were not adequately addressed at LTR. Postoperative factors for failure were poor follow-up in 2, anterior suprastomal collapse in 2, and slipped or broken stent in 2. Other factors that contributed to LTR failures included intractable gastroesophageal reflux disease in 1 procedure and keloid formation in 5.

CONCLUSIONS

Although some LTRs may fail secondary to factors that are not under the surgeon's control, many LTR failures can be avoided by accurate preoperative and intraoperative assessment of the stenosis, correct choice of surgical procedure, and close postoperative monitoring.

Characteristics of the intracavity dispersion in an erbium-doped fiber laser

We have found theoretically that the intracavity dispersion of a laser is independent of the pumping power and wavelength and that the resonant group-velocity dispersion vanishes. We have experimentally observed that the intracavity dispersion of an erbium-doped fiber laser was independent of the pumping power and wavelength within the measuring error, which agrees well with our theoretical predictions.

Clinical applications of transiently evoked otoacoustic emissions in the pediatric population

Our objectives were 1) to determine whether transiently evoked otoacoustic emissions (TEOAEs) are affected by the status of the tympanic membrane (TM) and middle ear (ME) as determined by clinical examinations and tympanograms; 2) to determine the efficacy of TEOAEs in detecting hearing loss; and 3) to determine the relative effects of the ME status and hearing loss on TEOAEs. In a prospective observational study in a tertiary care children's hospital, 89 patients (169 ears; 9 ears eliminated from analyses) were examined by 2 attending pediatric otolaryngologists for otologic conditions and underwent audiologic evaluations including TEOAEs from August 1994 through May 1995. The main outcome measures were presence or absence of TEOAE whole reproducibility (WR) and reproducibility (R) at 2 kHz. Statistical analyses showed that of the 8 ME and TM conditions evaluated (normal, TM perforation, pressure equalization [PE] tube, TM retraction, tympanosclerosis, TM atrophy, ME effusion, surgery other than PE tube insertion), only the presence of ME effusion and normal examination findings had a significant effect on the results of WR and R at 2 kHz. Of the 6 different types of tympanograms evaluated (A, B, C, AD, As, B with large volume), type A, B, and C tympanograms had a significant effect on WR and types A and B had a significant effect on R at 2 kHz. Hearing losses > or = 25 dB hearing level (HL) at any of the 5 frequencies (0.25, 0.5, 1, 2, and 4 kHz) were well predicted by the absence of WR and R at 2 kHz. When clinical examination and impedance data were evaluated simultaneously with hearing status, hearing status had a greater effect on WR and R at 2 kHz. We conclude that type B and C tympanograms and the presence of ME effusion (which reflect abnormal ME status) have an adverse effect on TEOAEs. However, the presence of hearing loss is the most significant predictor of TEOAE results. The TEOAE WR and R at 2 kHz are effective in identifying patients with normal hearing and with hearing losses > or = 25 dB HL.

Expression of Bfl-1 in normal and tumor tissues: Bfl-1 overexpression in cancer is attributable to its preferential expression in infiltrating inflammatory cells

Bfl-1, a member of the Bcl-2 gene family, blocks p53-mediated apoptosis and has oncogenic transforming activity. In normal tissues, the transcript of Bfl-1 is expressed abundantly in bone marrow and at a low level in several other tissues. In previous experiments, elevated expression of Bfl-1 was observed by Northern analysis of stomach cancer samples. To study the role of Bfl-1 in normal cell development and in tumorigenesis, we have analyzed the expression of Bfl-1 in normal and tumor tissues by the in situ hybridization technique. The Bfl-1 transcript was detected in the white pulp of the spleen and in the germinal center of lymphatic tissues. In tumor tissues, its expression was preferentially detected in infiltrating inflammatory cells rather than in cancer cells, suggesting that Bfl-1 is not involved in tumorigenesis.

Dynamic-strain measurement with dual-grating fiber sensor

A dual-grating sensor head, which was designed for temperature-insensitive strain measurement, was used to measure fast-varying strain perturbations. Using a Mach-Zehnder interferometer technique, we obtained ~0.1-muepsilon (microstrain) rms resolution with a 200-Hz strain input. The feasibility of measuring a dynamic-strain with a static-strain measuring configuration was also demonstrated.

Efficient Single-Mode GaAs/AlGaAs W Waveguide Phase Modulator with a Low Propagation Loss

We report a single-mode P-P-p-i-n-N-N GaAs/AlGaAs W waveguide phase modulator with a high phase modulation efficiency and a low propagation loss. The phase modulator with a W-shaped refractive-index profile utilizes a novel epilayer structure to reduce the propagation loss associated with doped layers and to obtain a phase modulation efficiency larger than those of P-i-N double heterostructure modulators. The phase shift and propagation loss were measured with a Fabry-Perot resonance method at 1.31-mum wavelength. A phase modulation efficiency as high as 34.6 degrees /V mm was measured for TE polarized light. Also propagation losses of less than 0.6 dB/cm were achieved. As a result, the W waveguide phase modulator that exhibits a high phase modulation efficiency and a low propagation loss have been experimentally realized for the first time as far as we know.

Displacements of the resonant peaks of a long-period fiber grating induced by a change of ambient refractive index

We present a graphic method of analyzing the spectral displacements of a long-period fiber grating as a function of ambient index. Mode dependence of the maximum displacement, disappearance of a particular resonance peak, and spectral behavior when the ambient index is larger than that of the cladding material are investigated and compared with experimental results.

Relative incidence and alternative approaches for surgical drainage of different types of deep neck abscesses in children

OBJECTIVES

To determine the relative frequency of retropharyngeal abscesses (RPAs) vs lateral pharyngeal abscesses (LPAs) and to analyze alternative approaches for surgical drainage.

DESIGN

Retrospective chart review.

SETTING

Tertiary care children's hospital.

PATIENTS

Seventy pediatric patients who were evaluated, admitted, and treated for presumed deep neck abscesses (RPAs and LPAs) between January 1, 1986, and December 31, 1996.

INTERVENTION

Intravenous antibiotic therapy and surgical drainage.

MAIN OUTCOME MEASURE

Clinical resolution of the abscess.

RESULTS

Fifty-eight patients were evaluated with computed tomographic scan. Thirteen of these patients did not have surgical intervention. Of 12 patients diagnosed as having an isolated RPA, all had intraoral surgical drainage and 9 had evidence of pus at surgery. Twenty-one patients had an isolated LPA. Sixteen of these underwent intraoral drainage and 5 underwent external drainage. Purulence was found at surgery in 14 and 2 patients, respectively. The remaining 12 patients had a combination of RPA and LPA. Eight patients underwent intraoral drainage, and 4 patients required both intraoral and external approaches. Purulence was found at surgery in 5 and 4 patients, respectively. Of the 12 patients who were not evaluated with computed tomographic scan, two thirds were treated prior to 1987. Six of these 12 patients underwent surgical drainage via an intraoral approach, and 4 of the 6 patients had pus. The remaining 6 improved without surgery.

CONCLUSIONS

Most deep neck abscesses in children are located in the retropharyngeal or in the lateral pharyngeal space medial to the great vessels. Therefore, most can be managed successfully with intraoral rather than external drainage. External approaches are better reserved for those abscesses that are lateral to the great vessels or that involve multiple spaces. In this patient population, LPAs were more commonly seen than RPAs.

Management of oropharyngeal trauma in children

OBJECTIVE

To determine the indications for admission, requisite imaging studies, and urgent medical or surgical intervention.

DESIGN

We retrospectively reviewed the charts of 26 children (age range, 5 months to 14 years) who were seen by the otolaryngology service in the emergency department at the Children's National Medical Center, Washington, DC, from 1985 to 1993 and who were diagnosed as having oropharyngeal trauma. We specifically looked for common findings in the history and physical examination on initial presentation to predict the necessary steps in evaluation and management.

SETTING

Tertiary care pediatric referral center.

RESULTS

Indications for admission were (1) concern about neurologic injury, (2) concern about vascular injury, (3) radiographic evidence of retropharyngeal free air or abscess, (4) pneumomediastinum, and (5) unreliable adult supervision at home. Six patients required surgery; 3 underwent retropharyngeal aspiration or incision and drainage procedures; 2 required neck explorations; and 1, who had an impaled foreign body in the parapharyngeal space, underwent surgical extraction. There were no vascular, neurologic, or other permanent injuries.

CONCLUSIONS

Oropharyngeal trauma may result in palatal and posterior pharyngeal wall injury requiring closure of lacerations and management of retropharyngeal free air. Rarely does an injury lead to retropharyngeal abscess or significant pneumomediastinum. Lateral oropharyngeal injuries require increased concern about potential neurovascular impairment. However, neither the mechanism of injury nor the degree of injury correlates with the potential for neurovascular sequelae. Since neurovascular involvement may not become clinically apparent until days or weeks after the incident, admission for observation alone should be based on the distance from the patient's home to the hospital and on the level of reliable adult supervision. Indications for medical and surgical treatment of internal carotid artery thrombosis remain controversial.

Expression of a novel Bcl-2 related gene, Bfl-1, in various human cancers and cancer cell lines

The expression of Bfl-1 gene, a novel Bcl-2 related gene, was determined by Northern blot analysis using a radiolabeled cDNA specific for Bfl-1 gene in 82 surgically resected tissue specimens of 28 gastric cancers, 15 colon cancers, nine breast cancers, eight bone and soft tissue sarcomas, five ovarian cancers, nine colon adenomas and eight gastric adenomas. A high rate of expression was observed in gastric and colon cancer, at 86 and 93%, respectively. In breast cancer, bone and soft tissue sarcoma and ovarian cancer, the expression rate was 33, 25 and 40%, respectively. In stomach cancer, the expression rate of Bfl-1 gene in metastatic lymph nodes was 82%, which was higher than 50% of the primary sites (p < 0.02). The intensity of RNA bands of the gastric cancer specimens was compared according to the stage, demonstrating that there was no difference in the expression levels of Bfl-1 gene between the stages in both primary sites and metastatic lymph nodes. Bfl-1 gene was expressed in three (33%) out of nine adenomas of the colon, while it was not detected in all eight gastric adenomas, We also examined the RNA expression of Bfl-1 gene in 22 human cancer cell lines consisting of five stomach cancer, four squamous cell carcinoma, three lung cancer, three cervical cancer, two colon cancer, two brain cancer, two leukemia and one osteosarcoma cell lines. Bfl-1 gene band was detected in one (5%) cervical cancer cell line, SiHa. The results of cancer tissue specimens indicate that Bfl-1 gene may play an important role in carcinogenesis of human cancers and may be involved in a relatively early phase of the adenoma-carcinoma sequence in colon cancer development. However, the mechanism responsible for the very low rate of expression in established cell lines is not clearly understood and further investigation is necessary to clarify the mechanism involved.

Interferometric temperature-insensitive strain measurement with different-diameter fiber Bragg gratings

An interferometric strain-sensing system that combines an unbalanced Mach-Zehnder wavelength discriminator and spliced different-diameter fiber Bragg gratings is presented that has the capability to distinguish strain from temperature effects. Because the gratings are written in 135- and 165- microm -diameter fibers drawn from the same preform, when they are spliced they show similar temperature sensitivities but different responses to applied strain. Thus the relative Bragg wavelength difference of the two gratings is affected only by strain, and one can measure it accurately by monitoring the amplitude variation of the interference signal rather than the conventional phase variation.

Cytotoxicity and multinucleate giant cell formation in Chinese hamster lung fibroblast caused by crocidolite and chrysotile

The mechanism of carcinogenic action of asbestos remains unclear but the physical properties of the fiber appear to be important in this process. Asbestos may cause multinucleate giant cell formation primarily by interfering with the normal course of mitosis. We evaluated the cytotoxicity and multinucleate giant cell formation induced by crocidolite and chrysotile in Chinese hamster lung fibroblast (V79 cell) with observation of phagocytic activities. Asbestos fibers were rapidly ingested by V79 cells and most fibers were inside the cells. Cytotoxicity was evaluated by observing inhibition of V79 cell proliferation with trypan blue exclusion test. For determination of frequency of multinucleate giant cells, the cells were treated with different doses of crocidolite or chrysotile for 72 hours. Crocidolite and chrysotile induced cytotoxicity in V79 cells in a dose-dependent manner. The pattern of inhibition of cell proliferation is similar for both types of fibers, but chrysotile was more potent at the highest level (20.0 micrograms/ml) of fiber concentration. There was a good relationship (regression coefficientcrocidolite = 0.02, P < 0.01; regression coefficientchrysotile = 0.04, P < 0.01) between the dose of both asbestos fibers and the frequency of multinucleate giant cells. Chrysotile was again more potent at inducing multinucleate giant cells in higher levels of fiber concentrations. We found that asbestos fibers were cytotoxic after phagocytosis and induced multinucleate giant cells by interfering mitosis.

Pneumomediastinum and pneumothorax from blunt cervical trauma in children

Minor blunt cervical injuries in children are relatively common occurrences leading to serious sequelae in only rare circumstances, yet sufficient impact of even a seemingly minor event may lead to a significant posterior tracheal wall laceration, resulting in pneumomediastinum with or without pneumothorax. Three cases demonstrate how the mechanism of injury does not always match either the severity of initial presentation or the consequent necessary level of emergent management. Pneumomediastinum without pneumothorax often can be treated conservatively; however, the onset of massive pneumomediastinum and pneumothorax may necessitate both tracheotomy and tube thoracostomy as initial treatment.