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Biomedical subjects

Richard E Davis

Publications and source records attributed to Richard E Davis.

16 recordsLinked to original sources
PubMed2005

Nasal valve surgery improves disease-specific quality of life.

OBJECTIVES/HYPOTHESIS: Disease-specific quality-of-life (QOL) assessment of patients with nasal valve compromise and symptomatic nasal obstruction has not been studied previously. The objectives of the study were to determine whether surgical treatment of the nasal valve improves disease-specific QOL and to identify clinical or demographic variables predictive of patients' baseline QOL or change in QOL. STUDY DESIGN: Prospective, multi-institutional outcomes study of 20 patients with nasal obstruction and a surgically treatable diagnosis of nasal valve compromise. METHODS: Disease-specific QOL assessment was performed using the Nasal Obstruction Symptom Evaluation (NOSE) scale preoperatively (n = 20) and at 3 (n = 14) and 6 months (n = 20) after surgery. Clinical and demographic data were collected, along with physician-reported assessments of degree of nasal obstruction. RESULTS: Mean NOSE scores significantly improved from baseline to 3 months after surgery (68.9 vs. 20.7 [P < .0001]), from baseline to 6 months after surgery (68.9 vs. 15.8 [P < .0001]), and from 3 to 6 months after surgery (20.7 vs. 15.8 [P = .0077]). Physician assessment of degree of nasal obstruction using a visual analogue scale was significantly correlated with baseline NOSE scores (P = .013) and change in NOSE scores at 6 months (P = .0015). No other clinical or demographic factors were found to be predictive. CONCLUSION: In patients with symptomatic nasal obstruction and nasal valve compromise, surgical repair of the nasal valve improves disease-specific QOL. Physician rating of degree of nasal obstruction was found to be significantly correlated with patient-reported QOL.

Adult↗
PubMed2004

Coherent differential absorption lidar measurements of CO2.

A differential absorption lidar has been built to measure CO2 concentration in the atmosphere. The transmitter is a pulsed single-frequency Ho:Tm:YLF laser at a 2.05-microm wavelength. A coherent heterodyne receiver was used to achieve sensitive detection, with the additional capability for wind profiling by a Doppler technique. Signal processing includes an algorithm for power measurement of a heterodyne signal. Results show a precision of the CO2 concentration measurement of 1%-2% 1sigma standard deviation over column lengths ranging from 1.2 to 2.8 km by an average of 1000 pulse pairs. A preliminary assessment of instrument sensitivity was made with an 8-h-long measurement set, along with correlative measurements with an in situ sensor, to determine that a CO2 trend could be detected.

Journal Article↗
PubMed2004

Contribution of trans-splicing, 5' -leader length, cap-poly(A) synergism, and initiation factors to nematode translation in an Ascaris suum embryo cell-free system.

Trans-splicing introduces a common 5' 22-nucleotide sequence with an N-2,2,7-trimethylguanosine cap (m (2,2,7)(3)GpppG or TMG-cap) to more than 70% of transcripts in the nematodes Caenorhabditis elegans and Ascaris suum. Using an Ascaris embryo cell-free translation system, we found that the TMG-cap and spliced leader sequence synergistically collaborate to promote efficient translation, whereas addition of either a TMG-cap or spliced leader sequence alone decreased reporter activity. We cloned an A. suum embryo eIF4E homolog and demonstrate that this recombinant protein can bind m(7)G- and TMG-capped mRNAs in cross-linking assays and that binding is enhanced by eIF4G. Both the cap structure and the spliced leader (SL) sequence affect levels of A. suum eIF4E cross-linking to mRNA. Furthermore, the differential binding of eIF4E to a TMG-cap and to trans-spliced and non-trans-spliced RNAs is commensurate with the translational activity of reporter RNAs observed in the cell-free extract. Together, these binding data and translation assays with competitor cap analogs suggest that A. suum eIF4E-3 activity may be sufficient to mediate translation of both trans-spliced and non-trans-spliced mRNAs. Bioinformatic analyses demonstrate the SL sequence tends to trans-splice close to the start codon in a diversity of nematodes. This evolutionary conservation is functionally reflected in the optimal SL to AUG distance for reporter mRNA translation in the cell-free system. Therefore, trans-splicing of the SL1 leader sequence may serve at least two functions in nematodes, generation of an optimal 5'-untranslated region length and a specific sequence context (SL1) for optimal translation of trimethylguanosine capped transcripts.

5' Untranslated Regions↗
PubMed2004

Technical factors in the creation of a "floppy" Nissen fundoplication.

The original description of "floppy" Nissen fundoplication was that of an open procedure involving a large esophageal bougie, complete fundic mobilization, ligation of the short gastric vessels, and placement of a finger or a dilator under the completed fundoplication to assure laxity. A maneuver equivalent to the latter step during laparoscopic Nissen fundoplication has not been described. The consensus in the literature appears to be that the element of a fundoplication that defines it as floppy is complete mobilization of the fundus. We report an intraoperative maneuver that assures the fundoplication has adequate laxity. We also discuss several other maneuvers to assure proper formation of the fundoplication and to minimize side effects such as long-term dysphagia.

Fundoplication↗
PubMed2004

Nematode m7GpppG and m3(2,2,7)GpppG decapping: activities in Ascaris embryos and characterization of C. elegans scavenger DcpS.

A spliced leader contributes the mature 5'ends of many mRNAs in trans-splicing organisms. Trans-spliced metazoan mRNAs acquire an m3(2,2,7)GpppN cap from the added spliced leader exon. The presence of these caps, along with the typical m7GpppN cap on non-trans-spliced mRNAs, requires that cellular mRNA cap-binding proteins and mRNA metabolism deal with different cap structures. We have developed and used an in vitro system to examine mRNA degradation and decapping activities in nematode embryo extracts. The predominant pathway of mRNA decay is a 3' to 5' pathway with exoribonuclease degradation of the RNA followed by hydrolysis of resulting mRNA cap by a scavenger (DcpS-like) decapping activity. Direct decapping of mRNA by a Dcp1/Dcp2-like activity does occur, but is approximately 15-fold less active than the 3' to 5' pathway. The DcpS-like activity in nematode embryo extracts hydrolyzes both m7GpppG and m3(2,2,7)GpppG dinucleoside triphosphates. The Dcp1/Dcp2-like activity in extracts also hydrolyzes these two cap structures at the 5' ends of RNAs. Interestingly, recombinant nematode DcpS differs from its human ortholog in its substrate length requirement and in its capacity to hydrolyze m3(2,2,7)GpppG.

Animals↗
PubMed2003

Is analysis of lower esophageal sphincter vector volumes of value in diagnosing gastroesophageal reflux disease?

AIM: With successful surgical treatment of gastroesophageal reflux disease (GERD), there is interest in understanding the anti-reflux barrier and its mechanisms of failure. To date, the potential use of vector volumes to predict the DeMeester score has not been adequately explored. METHODS: 627 patients in the referral database received esophageal manometry and ambulatory 24-hour pH monitoring. Study data included LES resting pressure (LESP), overall LES length (OL) and abdominal length (AL), total vector volume (TVV) and intrabdominal vector volume (IVV). RESULTS: In cases where LESP, TVV or IVV were all below normal, there was an 81.4 % probability of a positive DeMeester score. In cases where all three were normal, there was an 86.9 % probability that the DeMeester score would be negative. Receiver-operating characteristics (ROC) for LESP, TVV and IVV were nearly identical and indicated no useful cut-off values. Logistic regression demonstrated that LESP and IVV had the strongest association with a positive DeMeester score; however, the regression formula was only 76.1 % accurate. CONCLUSION: While the indices based on TVV, IVV and LESP are more sensitive and specific, respectively, than any single measurement, the measurement of vector volumes does not add significantly to the diagnosis of GERD.

Adolescent↗
PubMed2003

Postmyotomy dysphagia after laparoscopic surgery for achalasia.

AIM: To determine predictive factors for postoperative dysphagia after laparoscopic myotomy for achalasia. METHODS: Logistic regression was used to investigate the possible association between the response (postoperative dysphagia, with two levels: none/mild and moderate/severe) and several plausible predictive factors. RESULTS: Eight patients experienced severe or moderate postoperative dysphagia. The logistic regression revealed that only the severity of preoperative dysphagia (with four levels: mild, moderate, severe, and liquid) was a marginally significant (P=0.0575) predictive factor for postoperative dysphagia. CONCLUSION: The severity of postoperative dysphagia is strongly associated with preoperative dysphagia. Preoperative symptomatology can significantly impact patient outcome.

Deglutition Disorders↗
PubMed2002

Assessment of the Wiener-Retinex process.

We assess the performance of the Retinex transformation, the Wiener restoration, and the combined Wiener-Retinex process in the context of the end-to-end model of color visual-communication channels for near-surface acquisition. We extend the formulations of panchromatic imaging for the nonlinear Retinex transformation and the linear Wiener and Wiener-Retinex restoration filters to color imaging. We further assess the accuracy by which colors are restored in the cases of uniform and spatially varying irradiance levels, and the shadow depth for which color consistency is still possible with reasonable accuracy. Finally, we assess the sensitivity of these processes to perturbations in the visual channel, including the image-gathering design and the spatial support of the Retinex transformation.

Journal Article↗
PubMed2002

Effects of folic acid.

Explore the source record for details and available documents.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

Expression of endothelin 1 in rat random-pattern skin flaps treated with topical nifedipine.

OBJECTIVE: To evaluate the relative tissue concentrations of the endogenous vasoactive peptide endothelin 1 (ET-1) in random-pattern skin flaps (RPSF) treated with either topical anti-ischemic drug therapy (nifedipine) or placebo. DESIGN: Prospective, randomized, placebo-controlled therapeutic trial. SUBJECTS: Adult male Sprague-Dawley rats. INTERVENTION: Experimental subjects underwent caudally based RPSFs using the modified McFarlane technique. Subjects received either topical anti-ischemic drug therapy (nifedipine; n = 6) or inert carrier ointment (placebo; n = 6). Treatment was initiated immediately following flap closure and continued every 6 hours for 5 days. At the end of the treatment period, the animals were killed and the concentration of ET-1 was determined using enzyme-linked immunosorbent assay. Representative tissues from nifedipine- and placebo-treated skin flaps were also analyzed for ET-1 using immunohistochemical stains. RESULTS: The ET-1 levels in the distal (necrotic) flap segments were increased by 4.53 pg/mL over baseline (nonnecrotic) flaps in the placebo-treated animals and decreased by 4.70 pg/mL below baseline in the nifedipine-treated group (P =.03). CONCLUSIONS: The correlation between tissue levels of ET-1 and the severity of tissue necrosis suggests that ET-1 may play a pivotal role in ischemic injury of RPSFs. Moreover, treatment with topical nifedipine may antagonize the vasoconstrictive effects of ET-1. Although immunohistochemical analysis revealed ET-1 staining within the flap microvasculature, no quantitative differences were detected between the nifedipine- and placebo-treated flaps. Further studies are needed to define the role of ET-1 in RPSF necrosis.

Administration, Topical↗
PubMedDate not supplied

Powered instrumentation for nasal bone reduction: advantages and indications.

OBJECTIVE: To evaluate power-assisted bone removal in cosmetic rhinoplasty. DESIGN: Nonrandomized, nonblinded, retrospective evaluation of consecutive case series. SETTING: Academic facial plastic surgery practice. INTERVENTIONS: Power-assisted bone removal in 105 consecutive rhinoplasties requiring nasal bone reduction. MAIN OUTCOME MEASURES: Subjective evaluation by patient and surgeon. RESULTS: Of the 105 patients undergoing power-assisted bone removal, 102 obtained satisfactory refinement of the nasal dorsum after 1 operation. Three patients required surgical revision of the nasal dorsum following power-assisted bony hump reduction. Of these, 2 required surgical revision for delayed bone regrowth, while the remaining patient required surgical treatment of a persistent bony hump. Ultimately, all 105 patients achieved satisfactory surgical results. No other surgical complications were observed. CONCLUSIONS: Power-assisted bone removal is a useful adjunct for bone removal in cosmetic rhinoplasty. This study confirms the previously reported advantages of powered instrumentation for patients with small bony humps or modest bony asymmetries. Moreover, because powered instrumentation is comparatively atraumatic, it may be preferable for use in nasal bones previously weakened by trauma, aging, or prior nasal surgery. Finally, because the powered nasal rasp permits rounding of the bone edges, the characteristic widening associated with flat hump reduction is reduced, and the need for aggressive sidewall infracture is diminished. Complications associated with power-assisted bone removal were rare.

Adult↗
PubMedDate not supplied

Rhinoplasty and the nasal SMAS augmentation graft: advantages and indications.

We evaluated the nasal superficial musculoaponeurotic system (SMAS) as an autologous augmentation graft material in the thick-skinned patient undergoing cosmetic rhinoplasty using a retrospective review. Representative case reports demonstrated preliminary long-term results after augmentation with the nasal SMAS graft in an academic rhinoplasty practice. En bloc excision of the nasal SMAS in thick-skinned patients produced uniformly favorable improvements in nasal tip definition without adverse sequelae. Moreover, in 10 patients, the harvested material was also used for volume augmentation at various adjacent nasal sites, including the radix, nasal sidewall, and nasal dorsum. Long-term follow-up ranging from 1 to 3 years suggests stable volume augmentation in this initial patient series. No donor morbidity was observed in properly selected patients, and enhancements in nasal tip definition were uniformly favorable. Additional studies are needed to more accurately characterize long-term nasal SMAS graft survival in all patients.

Adolescent↗
PubMedDate not supplied

Diagnosis and surgical management of the caudal excess nasal deformity.

Surgical correction of the overgrown columella-labial junction remains a controversial and neglected aspect of cosmetic rhinoplasty. Failure to reduce an obtuse nasolabial angle resulting from overgrowth of the septum and/or nasal spine may adversely affect the otherwise satisfactory cosmetic result. I review the historical considerations regarding caudal overgrowth and discuss its relevance to contemporary rhinoplasty. Case studies are presented to illustrate surgical treatment options for various overgrowth deformities.

Adult↗