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Scott Ferguson

Publications and source records attributed to Scott Ferguson.

7 recordsLinked to original sources
PubMed2025

Recurrent structural variation and recent turnover at the 17q21.31 locus in humans and great apes.

The 17q21.31 locus in humans harbors several complex structural haplotypes including a ~970kb inversion. Different inversion haplotypes have been associated with susceptibility to microdeletions causing Koolen-de Vries syndrome and variation in fecundity and recombination rates. Here, using 210 haplotype-resolved human genome assemblies and pangenome graph-based approaches we characterize 11 distinct structural haplotypes, several of which have not been previously described. Extending our analyses to a set of haplotype-resolved great-ape genomes, we characterize the structure of an independent inversion in chimpanzees which extends an additional 650kb, encompasses 5 additional genes, and is ~2 million years younger than the human inversion. We further determine that gorillas exhibit an independent duplication of the KANSL1 gene which may predispose them to Koolen-de Vries syndrome causing microdeletions. Using short read sequencing data we characterize 17q21.31 haplotype diversity worldwide in ~5174 individuals from 107 populations finding increased frequencies of KANSL1 duplication-containing haplotypes in both European and South Asian populations as well as 8 double recombination events between inverted and non-inverted haplotypes ranging in size from 20-180kb. Finally, using 626 ancient Eurasian human genomes we show the frequency of haplotypes containing KANSL1 duplications has increased ~6-fold over the past 12 thousand years in Europe. Together, our results highlight the dynamics, complexity, and recurrent, independent evolution of a medically relevant locus across humans and great apes.

Journal Article↗
PubMed2005

Doing our part.

Explore the source record for details and available documents.

Arkansas↗
PubMed2004

Infrared imaging of subcutaneous veins.

BACKGROUND AND OBJECTIVES: Imaging of subcutaneous veins is important in many applications, such as gaining venous access and vascular surgery. Despite a long history of medical infrared (IR) photography and imaging, this technique is not widely used for this purpose. Here we revisited and explored the capability of near-IR imaging to visualize subcutaneous structures, with a focus on diagnostics of superficial veins. STUDY DESIGN/MATERIALS AND METHODS: An IR device comprising a head-mounted IR LED array (880 nm), a small conventional CCD camera (Toshiba Ik-mui, Tokyo, Japan), virtual-reality optics, polarizers, filters, and diffusers was used in vivo to obtain images of different subcutaneous structures. The same device was used to estimate the IR image quality as a function of wavelength produced by a tunable xenon lamp-based monochrometer in the range of 500-1,000 nm and continuous-wave Nd:YAG (1.06 microm) and diode (805 nm) lasers. RESULTS: The various modes of optical illumination were compared in vivo. Contrast of the IR images in the reflectance mode was measured in the near-IR spectral range of 650-1,060 nm. Using the LED array, various IR images were obtained in vivo, including images of vein structure in a pigmented, fatty forearm, varicose leg veins, and vascular lesions of the tongue. CONCLUSION: Imaging in the near-IR range (880-930 nm) provides relatively good contrast of subcutaneous veins, underscoring its value for diagnosis. This technique has the potential for the diagnosis of varicose veins with a diameter of 0.5-2 mm at a depth of 1-3 mm, guidance of venous access, podiatry, phlebotomy, injection sclerotherapy, and control of laser interstitial therapy.

Forearm↗
PubMed2004

A new mathematical approach to the diffusion approximation theory for selective photothermolysis modeling and its implication in laser treatment of port-wine stains.

BACKGROUND AND OBJECTIVES: Monte Carlo (MC) simulations of light-tissue interactions and analytical solutions for the diffusion approximation theory have been used to determine the optimal laser wavelength and radiant exposure to treat port-wine stains (PWS). Both approaches suggest that optimal parameters are a wavelength of 585 or 595-nm with pulse times of 0.45-20 milliseconds. However, which parameters are optimal is still unclear. As differences in vessel size and in temperature distribution within vessels appeared to be the main reasons for the varied responses to the same laser treatments, we sought to develop a solution to the diffusion approximation in order to calculate temperature distribution and the resulting coagulation pattern within specific blood vessels. STUDY DESIGN/MATERIALS AND METHODS: The light and heat diffusion equations were simultaneously solved with the finite element method (FEM). The latent heat of evaporation was included in the thermal analysis. The temperature and coagulation patterns across specific blood vessels, within a heterogeneous medium, were calculated for laser wavelengths of 585 and 595-nm with clinical parameters. RESULTS: At 1.2 mm deep, the calculations predicted that vessels ranging from 50 to 100 microm in diameter would be coagulated from top to bottom, small vessels (10 microm) would be spared, and vessels larger than 150 microm would be partially coagulated. Coagulation across vessels was more uniform for the 595-nm than for the 585-nm wavelength. Maximal temperatures did not exceed 100 degrees C because of the inclusion of latent heat in the thermal calculations. CONCLUSIONS: To study laser treatments of PWS with the diffusion approximation, FEM is an effective method to calculate the coagulation patterns within specific blood vessels. To improve coagulation efficacy at 585 and 595-nm wavelengths, the radiant exposure should be increased without increasing the irradiance.

Body Temperature↗
PubMed2002

The relative importance of left atrial function versus dimension in predicting atrial fibrillation after coronary artery bypass graft surgery.

BACKGROUND: Atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. The purpose of this study was to determine whether pre-existing left atrial dysfunction is a predictor of postoperative AF compared with other clinical predictors. METHODS: Ninety-three patients undergoing CABG were prospectively studied. Intraoperatively, transesophageal echocardiography was performed to measure left atrial size, transmitral flow velocity, and other routine parameters. Left atrial function was estimated by the following formula: Atrial index = Transmitral VTI total x LAEF/Left atrial maximal area (where VTI = velocity time integral of E and A waves, LAEF = left atrial ejection fraction). The association of potential clinical predictors with the occurrence of postoperative AF was evaluated by chi2 or Fisher exact tests, followed by stepwise multivariate logistic regression model. P values and odds ratios (OR) with 95% CIs were reported. Significance was set at P <.05. RESULTS: Postoperative AF occurred in 28 of 93 patients (30.1%). Patients with postoperative AF were older (67.0 +/- 8.3 vs 61.5 +/- 9.6 years, P =.0075), had larger left atrial maximal area (14.3 +/- 4.6 cm(2) vs 10.9 +/- 4.3 cm2, P <.001), lower atrial index (0.54 +/- 0.56 vs 0.82 +/- 0.64, P =.008), larger body surface area (BSA) (OR 57, 95% CI 3.97-827), longer aortic cross-clamp time (OR 1.03, 95% CI 1.00-1.05), and more likely to have a postoperative myocardial infarction (OR 3.28, 95% CI 0.99-10.87) compared with those without AF. By multivariate analysis, only age (OR 1.11, 95% CI 1.04-1.19, P =.002) and atrial dimension (OR 1.75, 95% CI 1.03-2.96, P =.038) were significant independent predictors of postoperative AF. Body surface area also increased the odds of postoperative AF, but the CI was wide (OR 114, 95% CI 4.65-2810, P =.004). CONCLUSIONS: Our results demonstrate that age and atrial enlargement, rather than atrial function, were independent predictors of postoperative AF.

Adult↗
PubMed2002

Photoacoustic effects of carbon dioxide lasers in stapes surgery: quantification in a temporal bone model.

HYPOTHESIS: The use of the CO2 laser in stapes surgery creates sound waves that could damage hearing. BACKGROUND The application of a laser to any medium has absorption, reflection, and thermal effects. To date, the majority of research on the safety of CO2 laser stapedotomy has focused on the thermal effects of the laser alone. Because of the properties of the CO2 laser, its absorption also presents some risk to the inner ear. This absorbed energy can be converted to photoacoustic or photochemical effects. The goal of this paper is to measure these photoacoustic effects (sounds) produced by the CO2 laser. METHODS: Using a variety of settings, a Sharplan 150 XJ Laser and a Contour model Erbium:YAG laser were applied to the oval window of human temporal bones. Perilymph was simulated by fixing the temporal bone in a normal saline bath. Photoacoustic waves were measured by a hydrophone 2 mm beneath the oval window. Measurements were made with and without a simulated tissue seal over the window. RESULTS: No detectable sounds were created below 4 watts (continuous mode) or 60 mJ (superpulse mode). Above those settings, intensities of 90 dB sound pressure level and higher were detected when the laser was applied directly to the perilymph. With the tissue seal in place, no detectable sounds were identified. The accuracy of this model was confirmed by comparing these results with previously published results using the Erbium:YAG laser. CONCLUSIONS: Below 4 watts in continuous wave mode and below 60 mJ in superpulse mode, any sound generated by the laser is small. Above these thresholds, however, impact sounds are produced that could result in threshold shifts with repeated applications.

Humans↗