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Rakestraw SL, Lucy AT, Wood LN, Chu DI, Grams J, Stahl R, Mustian MN. Racial Disparity in Length of Stay Following Implementation of a Bariatric Enhanced Recovery Program. J Surg Res 2024; 298:81-87. [PMID: 38581766 DOI: 10.1016/j.jss.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/18/2024] [Accepted: 03/11/2024] [Indexed: 04/08/2024]
Abstract
INTRODUCTION Enhanced Recovery Programs (ERPs) mitigate racial disparities in postoperative length of stay (LOS) for colorectal populations. It is unclear, however, if these effects exist in the bariatric surgery population. Therefore, this study aimed to evaluate the racial disparities in LOS before and after implementation of bariatric surgery ERP. METHODS A retrospective cohort study was performed using data from a single institution. Patients undergoing minimally invasive sleeve gastrectomy or Roux-en-Y gastric bypass from 2017 to 2019 (pre-ERP) or 2020-2022 (ERP) were included. Chi-square, Kruskal-Wallis, and analysis of variance were used to compare groups, and estimated LOS (eLOS) was assessed via multivariable regression. RESULTS Seven hundred sixty four patients were identified, including 363 pre-ERPs and 401 ERPs. Pre-ERP and ERP cohorts were similar in age (median 44.3 years versus 43.8 years, P = 0.80), race (53.4% Black versus 56.4% Black, P = 0.42), and preoperative body mass index (median 48.3 versus 49.4, P = 0.14). Overall median LOS following bariatric surgery decreased from 2 days pre-ERP to 1 day following ERP (P < 0.001). Average LOS for Black and White patients decreased by 0.5 and 0.48 days, respectively. However, overall eLOS remained greater for Black patients compared with White patients despite ERP implementation (eLOS 0.21 days, P = 0.01). CONCLUSIONS Implementation of a bariatric surgery ERP was associated with decreased LOS for both Black and White patients. However, Black patients did have slightly longer LOS than White patients in both pre-ERP and ERP eras. More work is needed to understand the driving mechanism(s) of these disparities to eliminate them.
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Affiliation(s)
| | - Adam T Lucy
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Lauren N Wood
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Daniel I Chu
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jayleen Grams
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama; Department of Surgery, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama
| | - Richard Stahl
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Margaux N Mustian
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
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Rakestraw SL, Novak Z, Wang M, Banks CA, Spangler EL, Levitan EB, Locke JE, Beck AW, Sutzko DC. Treatment Location Variation for Chronic Limb-Threatening Ischemia in Patients With Kidney Failure. J Surg Res 2024; 293:300-306. [PMID: 37806215 PMCID: PMC10799673 DOI: 10.1016/j.jss.2023.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 08/13/2023] [Accepted: 09/04/2023] [Indexed: 10/10/2023]
Abstract
INTRODUCTION End-stage kidney disease (ESKD) is an established risk factor for chronic limb-threatening ischemia (CLTI). Procedural location for ESKD patients has not been well described. This study aims to examine variation in index procedural location in ESKD versus non-ESKD patients undergoing peripheral vascular intervention for CLTI and identify preoperative risk factors for tibial interventions. METHODS Chronic limb-threatening ischemia (CLTI) patients were identified in the Vascular Quality Initiative (VQI) peripheral vascular intervention dataset. Patient demographics and comorbidities were compared between patients with and without ESKD and those undergoing index tibial versus nontibial interventions. A multivariable logistic regression evaluating risk factors for tibial intervention was conducted. RESULTS A total of 23,480 procedures were performed on CLTI patients with 13.6% (n = 3154) with ESKD. End-stage kidney disease (ESKD) patients were younger (66.56 ± 11.68 versus 71.66 ± 12.09 y old, P = 0.019), more often Black (40.6 versus 18.6%, P < 0.001), male (61.2 versus 56.5%, P < 0.001), and diabetic (81.8 versus 60.0%, P < 0.001) than non-ESKD patients. Patients undergoing index tibial interventions had higher rates of ESKD (19.4 versus 10.6%, P < 0.001) and diabetes (73.4 versus 57.5%, P < 0.001) and lower rates of smoking (49.9 versus 73.0%, P < 0.001) than patients with nontibial interventions. ESKD (odds ratio (OR) 1.67, 95% confidence interval (CI) 1.52-1.86, P < 0.001), Black race (OR 1.19, 95% CI 1.09-1.30, P < 0.001), and diabetes (OR 1.82, 95% CI 1.71-2.00, P < 0.001) were risk factors for tibial intervention. CONCLUSIONS Patients with ESKD and CLTI have higher rates of diabetes and tibial disease and lower rates of smoking than non-ESKD patients. Tibial disease was associated with ESKD, diabetes, and Black race.
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Affiliation(s)
| | - Zdenek Novak
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Michael Wang
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Charles A Banks
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Emily L Spangler
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Emily B Levitan
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jayme E Locke
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Adam W Beck
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Danielle C Sutzko
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
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Rakestraw SL, Novak Z, Wang MY, Banks CA, Spangler EL, Levitan EB, Locke JE, Beck AW, Sutzko DC. Differences in Long-Term Outcomes in End-Stage Kidney Disease Patients with Chronic Limb-Threatening Ischemia. Ann Vasc Surg 2023; 95:162-168. [PMID: 37225013 PMCID: PMC10799672 DOI: 10.1016/j.avsg.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/05/2023] [Accepted: 05/07/2023] [Indexed: 05/26/2023]
Abstract
BACKGROUND End-stage kidney disease (ESKD) is a risk factor for peripheral arterial disease and major adverse limb events following infra-inguinal bypass. Despite comprising an important patient population, ESKD patients are rarely analyzed as a subgroup and are underrepresented in vascular surgery guidelines. This study aims to compare the long-term outcomes of patients with and without ESKD undergoing endovascular peripheral vascular intervention (PVI) for chronic limb-threatening ischemia (CLTI). METHODS CLTI patients with and without ESKD from 2007-2020 were identified in the Vascular Quality Initiative PVI dataset. Patients with prior bilateral interventions were excluded. Patients undergoing femoral-popliteal and tibial interventions were included. Mortality, reintervention, amputation, and occlusion rates at 21 months following intervention were examined. Statistical analyses were completed with the t-test, chi-square, and Kaplan-Meier curves. RESULTS The ESKD cohort was younger (66.4 ± 11.8 vs. 71.6 ± 12.1 years, P < 0.001) with higher rates of diabetes (82.2 vs. 60.9%, P < 0.001) the non-ESKD cohort. Long-term follow-up was available for 58.4% (N = 2,128 procedures) of ESKD patients and 60.8% (N = 13,075 procedures) of non-ESKD patients. At 21 months, ESKD patients had a higher mortality (41.7 vs. 17.4%, P < 0.001) and a higher amputation rate (22.3 vs. 7.1%, P < 0.001); however, they had a lower reintervention rate (13.2 vs. 24.6%, P < 0.001). CONCLUSIONS CLTI patients with ESKD have worse long-term outcomes at 2 years following PVI than non-ESKD patients. Mortality and amputation are higher with ESKD, while the reintervention rate is lower. Development of guidelines within the ESKD population has the potential to improve limb salvage.
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Affiliation(s)
| | - Zdenek Novak
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Michael Y Wang
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Charles A Banks
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Emily L Spangler
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Emily B Levitan
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Jayme E Locke
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Adam W Beck
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Danielle C Sutzko
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL.
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Lucy AT, Rakestraw SL, Stringer C, Chu D, Grams J, Stahl R, Mustian MN. Readability of patient education materials for bariatric surgery. Surg Endosc 2023:10.1007/s00464-023-10153-3. [PMID: 37277519 DOI: 10.1007/s00464-023-10153-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 05/20/2023] [Indexed: 06/07/2023]
Abstract
INTRODUCTION Bariatric surgery is a successful treatment for obesity, but barriers to surgery exist, including low health literacy. National organizations recommend patient education materials (PEM) not exceed a sixth-grade reading level. Difficult to comprehend PEM can exacerbate barriers to bariatric surgery, especially in the Deep South where high obesity and low literacy rates exist. This study aimed to assess and compare the readability of webpages and electronic medical record (EMR) bariatric surgery PEM from one institution. METHODS Readability of online bariatric surgery and standardized perioperative EMR PEM were analyzed and compared. Text readability was assessed by validated instruments: Flesch Reading Ease Formula (FRE), Flesch Kincaid Grade Level (FKGL), Gunning Fog (GF), Coleman-Liau Index (CL), Simple Measure of Gobbledygook (SMOG), Automated Readability Index (ARI), and Linsear Write Formula (LWF). Mean readability scores were calculated with standard deviations and compared using unpaired t-tests. RESULTS 32 webpages and seven EMR education documents were analyzed. Webpages were overall "difficult to read" compared to "standard/average" readability EMR materials (mean FRE 50.5 ± 18.3 vs. 67.4 ± 4.2, p = 0.023). All webpages were at or above high school reading level: mean FKGL 11.8 ± 4.4, GF 14.0 ± 3.9, CL 9.5 ± 3.2, SMOG 11.0 ± 3.2, ARI 11.7 ± 5.1, and LWF 14.9 ± 6.6. Webpages with highest reading levels were nutrition information and lowest were patient testimonials. EMR materials were sixth to ninth grade reading level: FKGL 6.2 ± 0.8, GF 9.3 ± 1.4, CL 9.7 ± 0.9, SMOG 7.1 ± 0.8, ARI 6.1 ± 1.0, and LWF 5.9 ± 0.8. CONCLUSION Surgeon curated bariatric surgery webpages have advanced reading levels above recommended thresholds compared to standardized PEM from an EMR. This readability gap may unintentionally contribute to barriers to surgery and affect postoperative outcomes. Streamlined efforts are needed to create materials that are easier to read and comply with recommendations.
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Affiliation(s)
- Adam Timothy Lucy
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA.
- UAB Department of Surgery, 1808 7th Ave South, Boshell Diabetes Building, Suite 202, Birmingham, AL, 35233, USA.
| | - Stephanie L Rakestraw
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
| | - Courtney Stringer
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
| | - Daniel Chu
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
| | - Jayleen Grams
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
- Surgical Services, Birmingham Veterans Affairs Medical Center, 700 19th Street South, Birmingham, AL, 35233, USA
| | - Richard Stahl
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
| | - Margaux N Mustian
- Department of Surgery, University of Alabama at Birmingham (UAB) Heersink School of Medicine, 1808 7th Ave South, BDB 505, Birmingham, AL, 35233, USA
- Surgical Services, Birmingham Veterans Affairs Medical Center, 700 19th Street South, Birmingham, AL, 35233, USA
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Kennedy GE, Bergstresser SL, Rakestraw SL, Novak Z, Corey B, Chen H, Sutzko DC. Does Chair of Surgery Gender Influence Divisional or Residency Program Director Gender Diversity? J Surg Res 2021; 267:224-228. [PMID: 34157491 DOI: 10.1016/j.jss.2021.05.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/26/2021] [Accepted: 05/07/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Workplace diversity is beneficial and results in new ideas and improved performance. Within surgery leadership, the gender gap is improving, but still present. Given the increasing number of women surgery department chairs, we aimed to examine the association of surgery chair gender with division and residency program director gender. We hypothesized that surgery departments with female leadership would have an increase in gender diversity compared to departments led by male chairs. MATERIALS AND METHODS A list of all surgery departments were compiled from the Society of Surgical Chairs website. Gender of department chair, division director and residency program director were examined and compared. Chair position term length was determined based on online public announcements, publicly available curriculum vitae, and institutional profile biographies. RESULTS Of 178 department chairs included, 10.7% were female, and 89.3% were male. There was no difference in female residency program director leadership between female versus male led programs (42.1 versus 26.1%, P= 0.147). Of the programs with female department chairs, only 29.4% had any female division directors compared to 54.6% led by male chairs (P= 0.055). When examining departments with ≥5 division directors, there was no difference in the average number of female division directors within departments led by female versus male chairs. There was a significant difference in length of surgery chairship, with female chairs holding the position for fewer years than male chairs (median time 5.3 (IQR = 3.4-5.8) versus 7.0 (IQR=4.3-12.3) years, P= 0.032). CONCLUSIONS Female department chair leadership was not associated with increased diversity in divisional leadership compared to departments of surgery led by males.
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Affiliation(s)
- Grace E Kennedy
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | | | | | - Zdenek Novak
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Britney Corey
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Herbert Chen
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
| | - Danielle C Sutzko
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL.
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Harrison JM, Rakestraw SL, Doane SM, Pucci MJ, Palazzo F, Chojnacki KA. Achalasia and obesity: patient outcomes and impressions following laparoscopic Heller myotomy and Dor fundoplication. Langenbecks Arch Surg 2020; 405:809-816. [PMID: 32583213 DOI: 10.1007/s00423-020-01912-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 06/16/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE The optimal management of achalasia in obese patients is unclear. For those who have undergone Heller myotomy and fundoplication, the long-term outcomes and their impressions following surgery are largely unknown. METHODS A retrospective review of patients who underwent laparoscopic Heller myotomy and Dor fundoplication (LHMDF) for achalasia was performed. From this cohort, Class 2 and 3 obese (BMI > 35 kg/m2) patients were identified for short- and long-term outcome analysis. RESULTS Between 2003 and 2015, 252 patients underwent LHMDF for achalasia, and 17 (7%) patients had BMI > 35 kg/m2. Pre-operative Eckardt scores varied from 2 to 9, and at short-term (2-4 week) follow-up, scores were 0 or 1. Ten (58%) patients had available long-term (2-144 months) follow-up data. Eckardt scores at this time ranged from 0 to 6. Symptom recurrence was worse for patients with BMI > 40 kg/m2 compared to patients with BMI < 40 kg/m2. BMI was largely unchanged at long-term follow-up regardless of pre-intervention BMI. Most patients were satisfied with surgery but would have considered a combined LHMDF and weight-loss procedure had it been offered. CONCLUSION LHMDF for achalasia in obese patients is safe and effective in the short term. At long-term follow-up, many patients had symptom recurrence and experienced minimal weight loss. Discussing weight-loss surgery at the time LHMDF may be appropriate to ensure long-term achalasia symptom relief.
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Affiliation(s)
- Jon M Harrison
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA. .,, Boston, USA.
| | - Stephanie L Rakestraw
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
| | - Stephen M Doane
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
| | - Michael J Pucci
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
| | - Francesco Palazzo
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
| | - Karen A Chojnacki
- Department of General Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
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Rakestraw SL, Ford WE, Tompkins RG, Rodgers MA, Thorpe WP, Yarmush ML. Antibody-targeted photolysis: in vitro immunological, photophysical, and cytotoxic properties of monoclonal antibody-dextran-Sn(IV) chlorin e6 immunoconjugates. Biotechnol Prog 1992; 8:30-9. [PMID: 1371392 DOI: 10.1021/bp00013a006] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A set of anti-melanoma immunoconjugates were prepared which contained chlorin e6: antibody molar ratios of 18.9:1, 11.2:1, 6.8:1, and 1.7:1. All immunoconjugates retained antigen binding activity regardless of the chromophore:antibody substitution ratio that was attained. In contrast, the ground-state absorption spectra of the immunoconjugates showed features which appeared to be dependent on the chromophore:antibody molar ratio. In addition, the quantum yield of singlet oxygen generated by the conjugated chromophores was observed to be significantly less than that observed with the unbound dye. Time-resolved absorbance spectroscopy of the chromophore excited triplet state indicated that the loss of singlet oxygen quantum yield resulted from diminished chromophore triplet yield. Analysis of data obtained from in vitro photolysis of target melanoma cells, in combination with that obtained from the immunochemical and photochemical studies, indicates that the observed immunoconjugate phototoxicity can be reasonably quantitatively represented by (1) the ability of the immunoconjugate to bind SK-MEL-2 cell surface antigen, (2) the amount of chromophore localized at the target cells by immunoconjugate binding, (3) the delivered dose of light at 634 nm, and (4) the singlet oxygen quantum yield of the antibody-bound photosensitizer. Though these data argue strongly for photolysis by the cumulative dosage of singlet oxygen at the cell membrane, nonetheless, the concurrent photoinduced release of other cytotoxic agents should not be ruled out.
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Affiliation(s)
- S L Rakestraw
- Center for Photochemical Sciences, Bowling Green State University, Ohio 43403
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Friedberg JS, Tompkins RG, Rakestraw SL, Warren SW, Fischman AJ, Yarmush ML. Antibody-targeted photolysis. Bacteriocidal effects of Sn (IV) chlorin e6-dextran-monoclonal antibody conjugates. Ann N Y Acad Sci 1991; 618:383-93. [PMID: 1706578 DOI: 10.1111/j.1749-6632.1991.tb27258.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Antibody-targeted photolysis is a technique for damaging or killing cells using light and an antibody-bound photosensitizer. In the present study, immunoconjugates were constructed to selectively kill Pseudomonas aeruginosa bacteria using tin (IV) chlorin e6 which was linked to dextran and then bound to the carbohydrate moiety of a monoclonal antibody specific for Pseudomonas aeruginosa Fisher type I polysaccharide antigen. Killing of Pseudomonas during mid-log phase growth was shown to be dependent upon light dose with complete bacterial cell killing observed at an irradiation dose of 80 J/cm2. Individual components of the immunoconjugates (e.g., antibody or chlorin alone) showed no bacterial cytotoxicity and immunoconjugates constructed with nonbinding antibodies were also ineffective as cytotoxic agents. These studies demonstrate that killing of gram negative bacteria using photoradiation is feasible and suggest that this methodology may be applicable in treatment of infections in man.
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Affiliation(s)
- J S Friedberg
- Surgical Services, Massachusetts General Hospital, Boston
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Rakestraw SL, Tompkins RG, Yarmush ML. Antibody-targeted photolysis: in vitro studies with Sn(IV) chlorin e6 covalently bound to monoclonal antibodies using a modified dextran carrier. Proc Natl Acad Sci U S A 1990; 87:4217-21. [PMID: 1693435 PMCID: PMC54079 DOI: 10.1073/pnas.87.11.4217] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A monoclonal antibody-dextran-Sn(IV) chlorin e6 immunoconjugate was prepared by a technique involving the site-specific covalent modification of the monoclonal antibody oligosaccharide moiety. Dextran carriers were synthesized with a single chain-terminal hydrazide group, which was used as the coupling point between the carrier and the monoclonal antibody carbohydrate. Selective in vitro photolysis of SK-MEL-2 human malignant melanoma cells was accomplished using several conjugates prepared from anti-melanoma 2.1 (chromophore:antibody molar ratios, 6.8 and 11.2). Phototoxicity, as measured by clonogenic assay, was dependent on the delivered dose of 634-nm light and was observed only for conjugates that bound SK-MEL-2 cells. As judged by competitive inhibition radioimmunoassay, conjugates prepared in this fashion showed excellent retention of antigen binding activity relative to the unmodified antibody.
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Affiliation(s)
- S L Rakestraw
- Department of Chemical and Biochemical Engineering, Rutgers University, Piscataway, NJ 08855-0909
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Abstract
Monoclonal antibody (MAb)-dextran-tin(IV) chlorin e6 (SnCe6) immunoconjugates were prepared by a new technique involving the use of reducing, terminal-modified dextran carriers and site-specific modification of the Fc oligosaccharide moiety on the antibodies. Dextran carriers were synthesized to increase the number of SnCe6 molecules attached to a MAb. The dextran carriers were coupled to the MAb via a single, chain-terminal hydrazide group to prevent aggregation of MAbs. Conjugates were prepared with antimelanoma MAb 2.1 containing up to 18.9 SnCe6 molecules per MAb. Under neutral conditions, no hydrolysis of the hydrazone bond between the MAb and the dextran carrier could be detected, and the hydrazone was not stabilized by reduction with NaCNBH3 or NaBH4. Analysis of the purified immunoconjugates showed that approximately two dextran carrier chains were attached to a MAb regardless of the number of SnCe6 molecules linked to a dextran carrier. Site-specific covalent attachment of the SnCe6-dextran chains to the MAb was confirmed by SDS-PAGE. HPLC analysis of the conjugates gave a single species eluting in the range of 200-240 kDa. As determined by a competitive inhibition radioimmunoassay using viable SK-MEL-2 human malignant melanoma cells, the conjugates showed excellent retention of antigen-binding activity relative to unconjugated MAb.
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Affiliation(s)
- S L Rakestraw
- Department of Chemical and Biochemical Engineering, Rutgers University, Piscataway, New Jersey 08855
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