Cedric Walker - Academia.edu (original) (raw)
Papers by Cedric Walker
network meta-analysis. The cost of bDMARDs was based on the treatment schedule using Redbook. Adm... more network meta-analysis. The cost of bDMARDs was based on the treatment schedule using Redbook. Administration costs, monitoring costs, and adverse events costs were included in the model. To adjust for a biosimilar, a discount rate of 20% were adjusted. Results: In the bDMARDs arm, the total lifetime cost per patient was USD 185,002, and the QALY gained per patient was 11.63. The palliative therapy arm resulted in lower lifetime costs and lower gains in QALYs per patient (USD 25,111 and 9.16 QALY). Thus, the ICER was estimated to be USD 64,720 per QALY gained in base-case analysis. The probability to be cost-effective through WTP (willingness to pay) threshold of $50,000 was 13.0%. Conclusions: Sequential biosimilar bDMARDs monotherapy for the treatment of moderately to severely active patients with RA can be considered cost-effective over cDMARD therapy from the US payer perspective.
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology
The use of near infrared spectroscopy for measuring cellular oxygen availability with cytochrome ... more The use of near infrared spectroscopy for measuring cellular oxygen availability with cytochrome oxidase redox measurements was proposed in 1977. However, accuracy of measurement in blood-perfused tissue has been controversial because of the difficulty of separating the hemoglobin cytochrome oxidase spectra. This paper proposes the use of spectra wavelength intervals recorded by a cooled charge coupled device type spectrophotometer and fast Fourier transfer filtering techniques for aa3 signal extraction. Results indicate the proposed technique and equipment are excellent candidates for non-invasive monitoring oxygen availability to cells in vivo.
Journal of bioengineering, 1977
The relationships between stimulus parameters and perceptions in a prosthetic feedback system wer... more The relationships between stimulus parameters and perceptions in a prosthetic feedback system were measured using psychophysical methods. Electrical stimulation of the median nerve produced a monotonic relation between frequency of stimulation and the perceived magnitude of the stimulus. There were two qualitatively different perceptions of the stimulation; one for low frequencies and one for high. These two qualities fit different psychophysical continuua, kind of stimulation, and amount of stimulation.
Bioelectrochemistry and Bioenergetics, 1985
The effect of 120 days exposure to a high-intensity (80 kV/m), 60 Hz electric field for 21 hours/... more The effect of 120 days exposure to a high-intensity (80 kV/m), 60 Hz electric field for 21 hours/day on selected organ weights was investigated under controlled conditions using a three-generation design with 135 field-exposed and 135 sham-exposed Sprague-Dawley rats. The relatively large sample size afforded sufficient statistical power to detect subtle effects. The strategy of data analysis and power of the experimental design are discussed. The organs examined were the pituitary, thymus, heart, lungs. liver, spleen, adrenals, kidneys, and testes. Average weights of both adrenals, both kidneys, and both testes from field-exposed animals were slightly but significantly heavier than sham-exposed weights. Average weight of the spleen of field-exposed animals was slightly but significantly lower than the sham-exposed weight. It was concluded that several of the observed differences in the internal organs resembled those caused by a mild stressor.
Biological psychiatry, 1982
Our findings indicate that a notable number of patients who have functional psychosis (50%) or se... more Our findings indicate that a notable number of patients who have functional psychosis (50%) or seizures (38%) show cerebellar vermal atrophy on visual inspection of CAT head scans, in contrast to 0.5% to 3.7% of patients with other disorders. In addition to the visual reading of 1700 scans in the present study, we used two methods to demonstrate cerebellar vermal atrophy objectively: (i) low-density measurements of the posterior fossa in relationship to total brain area, and (ii) sagittal reconstruction of the vermis. We postulate that cerebellar vermal atrophy reduces the cerebellum's inhibitory influences on activity of the rostral forebrain structures where unit overactivity has been correlated with emotional dyscontrol and clinical seizures. We further postulate that cerebellar vermal atrophy reduces facilitory activity of the brain's pleasure system (septal region).
Cerebellar Stimulation for Spasticity and Seizures, 2021
The Journal of the …, 1987
Vowel discrimination using different frequency‐to‐electrode maps in cochlear implant users. [The ... more Vowel discrimination using different frequency‐to‐electrode maps in cochlear implant users. [The Journal of the Acoustical Society of America 82, S71 (1987)]. Mario A. Svirsky, John K. Cullen, Howard P. Ragland, Cedric F. Walker. Abstract. ...
Engineering in Medicine and Biology Society, 1991
Page 1. Clinical Engineering 11.1-1 INSTRUMENTATION IN THE CLINICAL ENGINEERING CURRICULUM Cedric... more Page 1. Clinical Engineering 11.1-1 INSTRUMENTATION IN THE CLINICAL ENGINEERING CURRICULUM Cedric F. Walker Department of Biomedical Engineering Tulane University, New Orleans LA 70118 USA ABSTRACT ...
IEEE transactions on bio-medical engineering, 1984
A study was undertaken to investigate subtle bioeffects in Sprague-Dawley rats chronically expose... more A study was undertaken to investigate subtle bioeffects in Sprague-Dawley rats chronically exposed to a 60-Hz electric field at 80 kV/m unperturbed intensity. The details of our exposure facility, artifact considerations, environmental conditions, and exposure protocol are reported in this paper. Results of electric field exposure on reproduction and prenatal and postnatal development of rats over four generations are discussed. Statistical analysis of data from 305 females, 213 pregnancies, and 2683 births revealed no effects of electric field exposure on fertility, fecundity, nurturing, survival, or sex ratio of offspring. In the final generation, 51 pregnant females were euthanized between days 16 and 20 of gestation, and 681 fetuses were carefully examined for gross malformations. Statistical analysis indicated that exposure to the electric field produced no significant increase in gross malformations, nor were any differences noted in resorptions, orientation of fetus in utero, sex ratio, or differential frequencies of uterine horn implantation. A detailed discussion of statistical power and sensitivity is included.
2004 Annual Conference Proceedings
2004 Annual Conference Proceedings
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society
This in vitro study was conducted to determine the direct effects of electric current and associa... more This in vitro study was conducted to determine the direct effects of electric current and associated increase in temper- ature on human sperm. Washed sperm samples from normal vol- unteers were subjected to an electric current (0 to 100 mA) in a small, customized Plexiglas chamber for up to 10 minutes. Resistive heating was monitored by a miniature temperature probe.
Proceedings of the Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Dec 7, 1988
Biomedical Instrumentation Technology Association For the Advancement of Medical Instrumentation, 2003
It is possible that many patients avoid complete ophthalmic exams because pupil dilation is slow,... more It is possible that many patients avoid complete ophthalmic exams because pupil dilation is slow, reversal sluggish, and vision blurred. Others experience incomplete dilation during exams or prior to surgery when good dilation is essential to successful outcome. Iontophoresis, the application of low-level electrical current to promote traversal of desired molecules across a boundary, has been used for many years and has recently become common in transdermal drug delivery. We now investigate iontophoresis as a method of accelerating drug absorption into the ocular anterior segment. In vivo rabbit studies assessed iontophoresis effects on the performance of dilators and constrictors. 1-mA and 4-mA direct current levels applied for 2-minute durations yielded dilation time-history measurements. Subsequent in vitro tests at a wide range of current densities showed minimal chemical modifications in ocular pharmaceuticals. Drug samples processed through high-performance liquid chromatography (HPLC) pinpointed minimal structural changes. Detailed in vivo rabbit testing is under way. Using 2 dilators and constrictors in crossed testing with 0.5-mA to 1.25-mA current levels and 20-sec to 60-sec durations, we recorded dilation progress by digital photography. Initial studies showed faster, larger dilations and quicker reversal using iontophoresis. Drug testing showed chemical structures remaining constant for clinically useful current levels, < or = 1 mA (< or = 1.25 mA/cm2 current density). Drug pH and HPLC retention times were constant within this range, and resistivity varied linearly as expected for increasing current. Rabbit testing will quantify improved drug speed and efficacy, validate the charge delivery electrode design, and indicate iontophoretic current and duration for further use. Tested ocular drugs showed no degradation when exposed to clinically useful iontophoretic currents. Preliminary results indicate significant time reductions for dilation and reversal, plus increases in maximum dilation. This procedure may aid clinicians by allowing more rapid complete examinations and surgical preparations for patients. Making dilation more convenient will also improve patient acceptance of exams, aiding earlier detection and treatment of ocular disease.
network meta-analysis. The cost of bDMARDs was based on the treatment schedule using Redbook. Adm... more network meta-analysis. The cost of bDMARDs was based on the treatment schedule using Redbook. Administration costs, monitoring costs, and adverse events costs were included in the model. To adjust for a biosimilar, a discount rate of 20% were adjusted. Results: In the bDMARDs arm, the total lifetime cost per patient was USD 185,002, and the QALY gained per patient was 11.63. The palliative therapy arm resulted in lower lifetime costs and lower gains in QALYs per patient (USD 25,111 and 9.16 QALY). Thus, the ICER was estimated to be USD 64,720 per QALY gained in base-case analysis. The probability to be cost-effective through WTP (willingness to pay) threshold of $50,000 was 13.0%. Conclusions: Sequential biosimilar bDMARDs monotherapy for the treatment of moderately to severely active patients with RA can be considered cost-effective over cDMARD therapy from the US payer perspective.
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology
The use of near infrared spectroscopy for measuring cellular oxygen availability with cytochrome ... more The use of near infrared spectroscopy for measuring cellular oxygen availability with cytochrome oxidase redox measurements was proposed in 1977. However, accuracy of measurement in blood-perfused tissue has been controversial because of the difficulty of separating the hemoglobin cytochrome oxidase spectra. This paper proposes the use of spectra wavelength intervals recorded by a cooled charge coupled device type spectrophotometer and fast Fourier transfer filtering techniques for aa3 signal extraction. Results indicate the proposed technique and equipment are excellent candidates for non-invasive monitoring oxygen availability to cells in vivo.
Journal of bioengineering, 1977
The relationships between stimulus parameters and perceptions in a prosthetic feedback system wer... more The relationships between stimulus parameters and perceptions in a prosthetic feedback system were measured using psychophysical methods. Electrical stimulation of the median nerve produced a monotonic relation between frequency of stimulation and the perceived magnitude of the stimulus. There were two qualitatively different perceptions of the stimulation; one for low frequencies and one for high. These two qualities fit different psychophysical continuua, kind of stimulation, and amount of stimulation.
Bioelectrochemistry and Bioenergetics, 1985
The effect of 120 days exposure to a high-intensity (80 kV/m), 60 Hz electric field for 21 hours/... more The effect of 120 days exposure to a high-intensity (80 kV/m), 60 Hz electric field for 21 hours/day on selected organ weights was investigated under controlled conditions using a three-generation design with 135 field-exposed and 135 sham-exposed Sprague-Dawley rats. The relatively large sample size afforded sufficient statistical power to detect subtle effects. The strategy of data analysis and power of the experimental design are discussed. The organs examined were the pituitary, thymus, heart, lungs. liver, spleen, adrenals, kidneys, and testes. Average weights of both adrenals, both kidneys, and both testes from field-exposed animals were slightly but significantly heavier than sham-exposed weights. Average weight of the spleen of field-exposed animals was slightly but significantly lower than the sham-exposed weight. It was concluded that several of the observed differences in the internal organs resembled those caused by a mild stressor.
Biological psychiatry, 1982
Our findings indicate that a notable number of patients who have functional psychosis (50%) or se... more Our findings indicate that a notable number of patients who have functional psychosis (50%) or seizures (38%) show cerebellar vermal atrophy on visual inspection of CAT head scans, in contrast to 0.5% to 3.7% of patients with other disorders. In addition to the visual reading of 1700 scans in the present study, we used two methods to demonstrate cerebellar vermal atrophy objectively: (i) low-density measurements of the posterior fossa in relationship to total brain area, and (ii) sagittal reconstruction of the vermis. We postulate that cerebellar vermal atrophy reduces the cerebellum's inhibitory influences on activity of the rostral forebrain structures where unit overactivity has been correlated with emotional dyscontrol and clinical seizures. We further postulate that cerebellar vermal atrophy reduces facilitory activity of the brain's pleasure system (septal region).
Cerebellar Stimulation for Spasticity and Seizures, 2021
The Journal of the …, 1987
Vowel discrimination using different frequency‐to‐electrode maps in cochlear implant users. [The ... more Vowel discrimination using different frequency‐to‐electrode maps in cochlear implant users. [The Journal of the Acoustical Society of America 82, S71 (1987)]. Mario A. Svirsky, John K. Cullen, Howard P. Ragland, Cedric F. Walker. Abstract. ...
Engineering in Medicine and Biology Society, 1991
Page 1. Clinical Engineering 11.1-1 INSTRUMENTATION IN THE CLINICAL ENGINEERING CURRICULUM Cedric... more Page 1. Clinical Engineering 11.1-1 INSTRUMENTATION IN THE CLINICAL ENGINEERING CURRICULUM Cedric F. Walker Department of Biomedical Engineering Tulane University, New Orleans LA 70118 USA ABSTRACT ...
IEEE transactions on bio-medical engineering, 1984
A study was undertaken to investigate subtle bioeffects in Sprague-Dawley rats chronically expose... more A study was undertaken to investigate subtle bioeffects in Sprague-Dawley rats chronically exposed to a 60-Hz electric field at 80 kV/m unperturbed intensity. The details of our exposure facility, artifact considerations, environmental conditions, and exposure protocol are reported in this paper. Results of electric field exposure on reproduction and prenatal and postnatal development of rats over four generations are discussed. Statistical analysis of data from 305 females, 213 pregnancies, and 2683 births revealed no effects of electric field exposure on fertility, fecundity, nurturing, survival, or sex ratio of offspring. In the final generation, 51 pregnant females were euthanized between days 16 and 20 of gestation, and 681 fetuses were carefully examined for gross malformations. Statistical analysis indicated that exposure to the electric field produced no significant increase in gross malformations, nor were any differences noted in resorptions, orientation of fetus in utero, sex ratio, or differential frequencies of uterine horn implantation. A detailed discussion of statistical power and sensitivity is included.
2004 Annual Conference Proceedings
2004 Annual Conference Proceedings
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society
This in vitro study was conducted to determine the direct effects of electric current and associa... more This in vitro study was conducted to determine the direct effects of electric current and associated increase in temper- ature on human sperm. Washed sperm samples from normal vol- unteers were subjected to an electric current (0 to 100 mA) in a small, customized Plexiglas chamber for up to 10 minutes. Resistive heating was monitored by a miniature temperature probe.
Proceedings of the Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Dec 7, 1988
Biomedical Instrumentation Technology Association For the Advancement of Medical Instrumentation, 2003
It is possible that many patients avoid complete ophthalmic exams because pupil dilation is slow,... more It is possible that many patients avoid complete ophthalmic exams because pupil dilation is slow, reversal sluggish, and vision blurred. Others experience incomplete dilation during exams or prior to surgery when good dilation is essential to successful outcome. Iontophoresis, the application of low-level electrical current to promote traversal of desired molecules across a boundary, has been used for many years and has recently become common in transdermal drug delivery. We now investigate iontophoresis as a method of accelerating drug absorption into the ocular anterior segment. In vivo rabbit studies assessed iontophoresis effects on the performance of dilators and constrictors. 1-mA and 4-mA direct current levels applied for 2-minute durations yielded dilation time-history measurements. Subsequent in vitro tests at a wide range of current densities showed minimal chemical modifications in ocular pharmaceuticals. Drug samples processed through high-performance liquid chromatography (HPLC) pinpointed minimal structural changes. Detailed in vivo rabbit testing is under way. Using 2 dilators and constrictors in crossed testing with 0.5-mA to 1.25-mA current levels and 20-sec to 60-sec durations, we recorded dilation progress by digital photography. Initial studies showed faster, larger dilations and quicker reversal using iontophoresis. Drug testing showed chemical structures remaining constant for clinically useful current levels, < or = 1 mA (< or = 1.25 mA/cm2 current density). Drug pH and HPLC retention times were constant within this range, and resistivity varied linearly as expected for increasing current. Rabbit testing will quantify improved drug speed and efficacy, validate the charge delivery electrode design, and indicate iontophoretic current and duration for further use. Tested ocular drugs showed no degradation when exposed to clinically useful iontophoretic currents. Preliminary results indicate significant time reductions for dilation and reversal, plus increases in maximum dilation. This procedure may aid clinicians by allowing more rapid complete examinations and surgical preparations for patients. Making dilation more convenient will also improve patient acceptance of exams, aiding earlier detection and treatment of ocular disease.