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Papers by Christopher Burks
Journal of Vascular Surgery: Venous and Lymphatic Disorders
Spine, Jan 16, 2015
Study Design. Retrospective database analysisObjective. To determine the impact of obesity on the... more Study Design. Retrospective database analysisObjective. To determine the impact of obesity on the rate of incidental durotomy in lumbar spine surgery.Summary of Background Data. There is a paucity of data on the overall impact of obesity on the rate of incidental durotomy in lumbar spine surgery specifically with regard to the type of procedure performed.Methods. A large administrative database was queried for all patients who underwent lumbar spine surgery for decompression and/or fusion. They were then stratified into separate cohorts based on body mass index (BMI) and by procedural codes. Documentation of incidental durotomy was noted. Patient demographics and associated comorbidities were assessed. Odds ratios and 95% confidence intervals were calculated and chi square test was used to assess for statistical significance.Results. The incidental durotomy ranged from 0.5-2.6% with the highest rates observed in multi-level laminectomies and revision decompressions in the obese and ...
Proceedings of the National Academy of Sciences, 1989
Journal of the American Academy of Audiology, 2006
In an initial experiment (Wilson and Weakley, 2004), word recognition was assessed with six digit... more In an initial experiment (Wilson and Weakley, 2004), word recognition was assessed with six digit triplets presented at 14 signal-to-babble ratios (S/B) in 2 dB steps. An abbreviated version of the protocol was developed for clinic use involving three digit triplets at 7 S/Bs in 4 dB steps. The purpose of this experiment was to examine the relationship between the two digit protocols with comparisons made with other variables including age, pure-tone thresholds, subjective measures of understanding speech in quiet and in noise, and word recognition of monosyllabic words in quiet and in babble. Ninety-six listeners with sensorineural hearing loss participated. For equivalent performance, the short version of the digit triplets required (1) a 2.6 dB more favorable S/B than the long version and (2) a 15.1 dB less favorable S/B than the words. Age, hearing loss, and subjective evaluation of the ability to understand speech in quiet and in noise were not related to performance on digits ...
Journal of the American Academy of Audiology, 2005
The purpose of this experiment was to determine the relationship between psychometric functions f... more The purpose of this experiment was to determine the relationship between psychometric functions for words presented in multitalker babble using a descending presentation level protocol and a random presentation level protocol. Forty veterans (mean = 63.5 years) with mild-to-moderate sensorineural hearing losses were enrolled. Seventy of the Northwestern University Auditory Test No. 6 words spoken by the VA female speaker were presented at seven signal-to-babble ratios from 24 to 0 dB (10 words/step). Although the random procedure required 69 sec longer to administer than the descending protocol, there was no significant difference between the results obtained with the two psychophysical methods. There was almost no relation between the perceived ability of the listeners to understand speech in background noise and their measured ability to understand speech in multitalker babble. Likewise, there was a tenuous relation between pure-tone thresholds and performance on the words in babb...
Journal of the American Academy of Audiology, 2005
The purpose of this mixed model design was to examine recognition performance differences when me... more The purpose of this mixed model design was to examine recognition performance differences when measuring speech recognition in multitalker babble on listeners with normal hearing (n = 36) and listeners with hearing loss (n = 72) utilizing stimulus of varying linguistic complexity (digits, words, and sentence materials). All listeners were administered two trials of two lists of each material in a descending speech-to-babble ratio. For each of the materials, recognition performances by the listeners with normal hearing were significantly better than the performances by the listeners with hearing loss. The mean separation between groups at the 50% point in signal-to-babble ratio on each of the three materials was ~8 dB. The 50% points for digits were obtained at a significantly lower signal-to-babble ratio than for sentences or words that were equivalent. There were no interlist differences between the two lists for the digits and words, but there was a significant disparity between Q...
The Journal of Rehabilitation Research and Development, 2005
The Journal of Rehabilitation Research and Development, 2005
Journal of Proteome Research, 2005
The Rev protein of HIV-1 is essential for HIV-1 proliferation due to its role in exporting viral ... more The Rev protein of HIV-1 is essential for HIV-1 proliferation due to its role in exporting viral RNA from the nucleus. We used a modified version of tandem affinity purification (TAP) tagging to identify proteins interacting with HIV-1 Rev in human cells and discovered a prominent interaction between Rev and nucleosome assembly protein 1 (Nap1). This interaction was also observed by specific retention of Nap1 from human cell lysates on a Rev affinity column. Nap1 was found to bind Rev through the Rev arginine-rich domain and altered the oligomerization state of Rev in vitro. Overexpression of Nap1 stimulated the ability of Rev to export RNA, reduced the nucleolar localization of Rev, and affected Rev nuclear import rates. The results suggest that Nap-1 may influence Rev function by increasing the availability of Rev.
Journal of Vascular Surgery: Venous and Lymphatic Disorders
Spine, Jan 16, 2015
Study Design. Retrospective database analysisObjective. To determine the impact of obesity on the... more Study Design. Retrospective database analysisObjective. To determine the impact of obesity on the rate of incidental durotomy in lumbar spine surgery.Summary of Background Data. There is a paucity of data on the overall impact of obesity on the rate of incidental durotomy in lumbar spine surgery specifically with regard to the type of procedure performed.Methods. A large administrative database was queried for all patients who underwent lumbar spine surgery for decompression and/or fusion. They were then stratified into separate cohorts based on body mass index (BMI) and by procedural codes. Documentation of incidental durotomy was noted. Patient demographics and associated comorbidities were assessed. Odds ratios and 95% confidence intervals were calculated and chi square test was used to assess for statistical significance.Results. The incidental durotomy ranged from 0.5-2.6% with the highest rates observed in multi-level laminectomies and revision decompressions in the obese and ...
Proceedings of the National Academy of Sciences, 1989
Journal of the American Academy of Audiology, 2006
In an initial experiment (Wilson and Weakley, 2004), word recognition was assessed with six digit... more In an initial experiment (Wilson and Weakley, 2004), word recognition was assessed with six digit triplets presented at 14 signal-to-babble ratios (S/B) in 2 dB steps. An abbreviated version of the protocol was developed for clinic use involving three digit triplets at 7 S/Bs in 4 dB steps. The purpose of this experiment was to examine the relationship between the two digit protocols with comparisons made with other variables including age, pure-tone thresholds, subjective measures of understanding speech in quiet and in noise, and word recognition of monosyllabic words in quiet and in babble. Ninety-six listeners with sensorineural hearing loss participated. For equivalent performance, the short version of the digit triplets required (1) a 2.6 dB more favorable S/B than the long version and (2) a 15.1 dB less favorable S/B than the words. Age, hearing loss, and subjective evaluation of the ability to understand speech in quiet and in noise were not related to performance on digits ...
Journal of the American Academy of Audiology, 2005
The purpose of this experiment was to determine the relationship between psychometric functions f... more The purpose of this experiment was to determine the relationship between psychometric functions for words presented in multitalker babble using a descending presentation level protocol and a random presentation level protocol. Forty veterans (mean = 63.5 years) with mild-to-moderate sensorineural hearing losses were enrolled. Seventy of the Northwestern University Auditory Test No. 6 words spoken by the VA female speaker were presented at seven signal-to-babble ratios from 24 to 0 dB (10 words/step). Although the random procedure required 69 sec longer to administer than the descending protocol, there was no significant difference between the results obtained with the two psychophysical methods. There was almost no relation between the perceived ability of the listeners to understand speech in background noise and their measured ability to understand speech in multitalker babble. Likewise, there was a tenuous relation between pure-tone thresholds and performance on the words in babb...
Journal of the American Academy of Audiology, 2005
The purpose of this mixed model design was to examine recognition performance differences when me... more The purpose of this mixed model design was to examine recognition performance differences when measuring speech recognition in multitalker babble on listeners with normal hearing (n = 36) and listeners with hearing loss (n = 72) utilizing stimulus of varying linguistic complexity (digits, words, and sentence materials). All listeners were administered two trials of two lists of each material in a descending speech-to-babble ratio. For each of the materials, recognition performances by the listeners with normal hearing were significantly better than the performances by the listeners with hearing loss. The mean separation between groups at the 50% point in signal-to-babble ratio on each of the three materials was ~8 dB. The 50% points for digits were obtained at a significantly lower signal-to-babble ratio than for sentences or words that were equivalent. There were no interlist differences between the two lists for the digits and words, but there was a significant disparity between Q...
The Journal of Rehabilitation Research and Development, 2005
The Journal of Rehabilitation Research and Development, 2005
Journal of Proteome Research, 2005
The Rev protein of HIV-1 is essential for HIV-1 proliferation due to its role in exporting viral ... more The Rev protein of HIV-1 is essential for HIV-1 proliferation due to its role in exporting viral RNA from the nucleus. We used a modified version of tandem affinity purification (TAP) tagging to identify proteins interacting with HIV-1 Rev in human cells and discovered a prominent interaction between Rev and nucleosome assembly protein 1 (Nap1). This interaction was also observed by specific retention of Nap1 from human cell lysates on a Rev affinity column. Nap1 was found to bind Rev through the Rev arginine-rich domain and altered the oligomerization state of Rev in vitro. Overexpression of Nap1 stimulated the ability of Rev to export RNA, reduced the nucleolar localization of Rev, and affected Rev nuclear import rates. The results suggest that Nap-1 may influence Rev function by increasing the availability of Rev.