AB1244 TOTAL KNEE ARTHROPLASTY IN PATIENTS UNDER 21 YEARS OF AGE: A U.S. NATIONWIDE ANALYSIS

Background

Total knee arthroplasty (TKA) is a procedure rarely performed in patients under 21 years old. However, the number of patients <21 undergoing TKA in the United States (US) is unknown. In one of the largest US studies of an institutional arthroplasty registry, only 19 TKAs were performed in patients <21 out of ~30,000 primary TKAs over 34 years1. While a few national or multi-national studies have been performed outside the US, these studies have small cohorts (~100), making it difficult to determine the indications for TKA in this age group.

Objectives

We identified the number of patients <21 years of age who underwent TKA in a US nationwide dataset. Additionally, we determined the epidemiological characteristics of patients undergoing TKA, including their age, sex, race, indications for surgery, and in-hospital mortality.

Methods

We analyzed the Kids’ Inpatient Database, which is a national weighted sample of all inpatient hospital admissions in the US in patients <21 years old from ~4,200 hospitals in 46 states. We included all admissions from 2000-2016 with a primary procedural code of TKA determined by ICD-9 and 10 codes. Descriptive statistics such as means and percentages, along with 95% confidence intervals were calculated using appropriate sample weights.

Results

The total number of TKAs performed in patients <21 years old from 2000 to 2016 was 1,331 (Table 1). The majority of TKAs performed (n=936; 70.3%) were for treatment of an oncologic disease. The most common diagnosis was malignant tumor (68.7%), followed by osteoarthritis (7.3%) and inflammatory arthritis or juvenile idiopathic arthritis (JIA) (7.0%) (Figure 1). Osteonecrosis accounted for 3.9% of cases, while mechanical complications accounted for 3.3%. Fewer than 2% of cases had an indication of either benign or uncertain tumor, infection, or trauma. The mean age was 14.8 years, and 48.4% of the cohort was female. A higher proportion of the non-tumor cohort was female (57.1%) than the tumor cohort (44.7%). 57.1% of patients in the overall cohort were White, and this proportion was smaller in the tumor group (53.8%) than the non-tumor group (64.9%). No patients died during the inpatient event. 87.8% of TKAs were performed in urban teaching hospitals.

Table 1.

Characteristics of patients <21 undergoing TKA by diagnosis type

VariableOverallN = 1331Non-tumorN = 395TumorN = 936Age, mean (95% CI)14.8 (14.4, 15.2)15.9 (14.7, 17.1)14.3 (14.1, 14.6)Sex: Female, % (95% CI)48.4 (44.9, 51.9)57.1 (49.1, 64.8)44.7 (41.1, 48.3)Race, % (95% CI) White57.1 (52.3, 61.8)64.9 (55.5, 73.3)53.8 (48.4, 59.2) Black13.1 (10.1, 16.9)16.9 (10.1, 27.2)11.5 (8.7, 14.9) Hispanic19.7 (16.6, 23.3)14.3 (9.9, 20.2)22.0 (18.1, 26.6) Asian or Pacific Islander3.4 (2.1, 5.4)**4.6 (2.9, 7.4) Native American0.9 (0.4, 1.9)**** Other5.8 (4.1, 8.1)2.9 (1.3, 6.4)7.0 (4.8, 10.0)Payor, % (95% CI) Medicare1.4 (0.7, 2.9)4.7 (2.2, 9.7)— Medicaid31.1 (27.5, 35.0)28.0 (21.0, 36.3)32.4 (28.3, 36.7) Private57.8 (53.7, 61.7)60.2 (52.1, 67.8)56.7 (52.2, 61.1) Self-pay3.3 (2.3, 4.9)**4.2 (2.7, 6.2) Other6.1 (4.4, 8.3)5.1 (3.0, 8.6)6.6 (4.5, 9.4)Admission type: elective, % (95% CI)85.9 (81.1, 89.6)81.6 (72.6, 88.2)87.7 (82.2, 91.6)

N represents weighted estimate

CI = Confidence Interval

** Per HCUP guidelines, cell sizes ≤10 have been omitted to protect patient confidentiality

Figure 1.

Most common primary diagnoses for TKA in patients <21 years old

The most common primary diagnosis of 1,331 patients <21 undergoing TKA. Bars represent 95% Confidence Intervals. JIA = juvenile idiopathic arthritis.

Conclusion

TKA is a rarely-performed procedure for patients <21 years old in the US; it is mainly performed in urban teaching centers and has excellent in-hospital survival rates. 70.3% of these procedures are performed for tumors—the vast majority of which are malignant. Also, even with the advent of better treatment options for JIA and inflammatory arthritis, TKA is still performed frequently in this population indicating that better clinical management is needed.

References

[1]Martin JR et al. Adolescent total knee arthroplasty. PMCID: PMC5484984

Acknowledgements

This work was supported by the Kellen Scholar Award supported by the Anna Marie and Stephen Kellen Foundation Total Knee Improvement Program. The authors would like to acknowledge the Healthcare Cost and Utilization Project Data Partners that contribute to Healthcare Cost and Utilization Project: Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.

Disclosure of Interests

J. Alex Gibbons: None declared, Cynthia Kahlenberg: None declared, Deanna Jannat-Khah Shareholder of: AstraZeneca, Cytodyn, and Walgreens, Susan Goodman Consultant of: UCB, Grant/research support from: Novartis, Peter Sculco Consultant of: Intellijoint Surgical, DePuy Synthes, Lima Corporate, Zimmer Biomet, and EOS Imaging, Grant/research support from: Intellijoint Surgical and Zimmer Biomet, Mark Figgie Shareholder of: HS2, Mekanika, and Wishbone, Consultant of: Lima and Wishbone, Bella Mehta Paid instructor for: Novartis

AB1465 BLACK PATIENTS ARE LESS SATISFIED WITH THE PROCESS OF CARE FOLLOWING PRIMARY HIP AND KNEE ARTHROPLASTY: A RETROSPECTIVE STUDY

Background

Patients’ post-operative satisfaction with their hospital experience is important to patient care, hospital reimbursement, and comparison between hospitals. The Press Ganey (PG) inpatient survey is commonly administered to assess patient satisfaction with the process of care. However, whether patient PG survey scores following primary unilateral hip and knee arthroplasty are associated with a patient’s race and socioeconomic status (SES) is unknown.

Objectives

We aimed to determine whether patient PG survey overall assessment scores differ by race and SES.

Methods

We linked data for patients in large institutional hip and knee arthroplasty registries consisting of surgeries from July 2010–February 2012 to their PG survey responses. Patients undergoing primary unilateral surgery of Black or White race who resided in New York, New Jersey, or Connecticut at the time of surgery were included in the analysis. The primary outcome variable was the PG overall assessment score, calculated as the mean of a patient’s ratings for the three questions in the “Overall Assessment” section of the PG survey and dichotomized as either completely satisfied (score of 100) or not completely satisfied (score <100). Primary payor was used as a proxy for patient SES. Multivariable logistic regression was performed for the hip and knee cohorts separately to determine if patient race and primary payor were associated with not being completely satisfied, adjusting for age, sex, and American Society of Anesthesiology (ASA) score.

Results

There were 2,516 hip patients and 2,113 knee patients with PG overall assessment scores included in the analyses (Table 1). Black patients were more likely to be not completely satisfied compared to White patients in both cohorts [hip (odds ratio (OR)=1.64; 95% confidence interval (CI): 1.03, 2.61; p=0.04)]; [knee (OR=1.83; 95% CI: 1.16, 2.88; p=0.01). In the hip cohort, patients between 70-79 years old (OR=1.71; 95% CI: 1.09, 2.67; p=0.02) and older than 80 years (OR=2.00; 95% CI: 1.20, 3.32; p<0.01) were more likely to be not completely satisfied. In the knee cohort, patients 50-59 years old (OR=0.56; 95% CI: 0.33, 0.97; p=0.04) and 60-69 years old (OR=0.57; 95% CI: 0.33, 0.96; p=0.03) were less likely to be not completely satisfied compared to patients <50 years old.

Table 1.

Likelihood of not being completely satisfied with the process of care (PG score <100)

VariableReferenceCategoryHip Cohort (n = 2,516)Knee Cohort (n = 2,113)Odds Ratio95% CIp-valueOdds Ratio95% CIp-valueAge Group<5050-591.02(0.69, 1.50)0.9390.56(0.32, 0.97)0.039<5060-691.04(0.70, 1.54)0.8580.57(0.33, 0.96)0.034<5070-791.71(1.09, 2.67)0.0190.63(0.36, 1.11)0.113<5080+2.00(1.20, 3.32)0.0080.97(0.53, 1.77)0.912SexFemaleMale0.84(0.69, 1.02)0.0821.03(0.83, 1.26)0.816RaceWhiteBlack1.64(1.03, 2.61)0.0381.83(1.16, 2.88)0.010ASA status121.04(0.70, 1.55)0.8321.23(0.60, 2.51)0.580131.45(0.91, 2.29)0.1161.36(0.64, 2.87)0.41914<0.01(0.00, ***)0.968<0.01(0.00, ***)0.977Primary PayorMedicareMedicaid1.35(0.26, 7.01)0.718<0.01(0.00, ***)0.983MedicareOther/Unknown1.24(0.94, 1.64)0.1260.87(0.65, 1.17)0.362MedicarePrivate1.13(0.61, 2.10)0.6881.01(0.57, 1.78)0.983

ASA = American Society of Anesthesiologist (ASA) physical status classification. PG = Press Ganey. CI = Confidence Interval. *** indicates >999.99. Bold indicates p < 0.05

Conclusion

Black patients were less likely to be completely satisfied compared to White patients following total hip and knee arthroplasty. More research is needed to investigate other factors such as perceived staff courtesy and baseline pain and function to understand why these disparities exist.

Acknowledgements

This work was supported by the Stavros Niarchos Complex Joint Reconstruction Center at Hospital for Special Surgery. The content is solely the responsibility of the authors and does not necessarily represent the official views of the center.

Disclosure of Interests

J. Alex Gibbons: None declared, Orett Burke Jr: None declared, Huong Do: None declared, Emily Ying Lai: None declared, Bella Mehta Paid instructor for: Novartis, Letitia Bradford: None declared, Michael Parks Consultant of: ZimmerBiomet, Linda Russell: None declared, Anne Bass: None declared, Mark Figgie Shareholder of: HS2, Mekanika, and Wishbone, Consultant of: Lima and Wishbone, Susan Goodman Consultant of: UCB, Grant/research support from: Novartis

OP0223 DISTINGUISHING OSTEOARTHRITIS AND RHEUMATOID ARTHRITIS SYNOVIUM WITH MACHINE LEARNING USING AUTOMATED CELL DENSITY AND PATHOLOGIST SCORES

Background

Joint damage in the knee can be severe in both rheumatoid arthritis (RA) and osteoarthritis (OA) such that total knee replacement (TKR) is often the only management option. Pathological assessment of the extent or type of synovial tissue inflammation from joint explants or biopsies can be useful. However, an ongoing challenge in using semi-quantitative assessments of synovitis is the disagreement between human pathologist scores of the same sample. We previously developed and validated a computer vision algorithm to automatically count each cell nucleus in an H&E-stained synovial whole slide image and yield a value of cell density, defined as mean nuclei count per mm2 of tissue1.

Objectives

We sought to develop methods to distinguish OA from RA based on machine learning analysis of histologic features on H&E-stained synovial tissue samples.

Methods

We measured 14 pathologist-scored histology features (137 RA and 152 OA patients) and computer vision quantified cell density (60 RA and 147 OA patients) in H&E stained synovial tissue samples from total knee replacement arthroplasty explants. A random forest model was trained using disease state (OA vs RA) as classifier and histology features and/or cell density as inputs, and feature importance scores for the model were calculated.

Results

Synovium from patients with RA exhibited increased lymphocytic inflammation, lining hyperplasia, neutrophils, detritus, plasma cells, Russell bodies, binucleate plasma cells, sub-lining giant cells, synovial lining giant cells, and fibrin (all p<0.001), while synovium from patients with OA had increased mast cells and fibrosis (both p<0.001). Fourteen pathologist-scored features allowed for discrimination between RA and OA samples, producing a macro-averaged area under the receiver operating curve (AUC) of 0.85. This discriminatory ability was comparable to that of the computer vision score of cell density alone (AUC = 0.88). Combining the pathologist scores with the cell density metric improved the discriminatory power of the model (AUC = 0.91). The three most important features in this combined model were mast cells followed by cell density and fibrosis (Figure 1). AUC values for each individual feature are provided in Table 1. The optimal cell density threshold to distinguish RA from OA synovium was 3,400 cells per mm2, which yielded a sensitivity of 0.82 and specificity of 0.82.

Table 1.

Area under receiver operating characteristic curves (AUC) of the synovial features in distinguishing RA and OA patients

FeatureAUCAutomated Cell Density0.88Fibrosis0.84Mast cells0.80Lining hyperplasia0.78Lymphocytic inflammation0.69Fibrin0.68Plasma cells0.66Detritus0.64Binucleate plasma cells0.60Neutrophils0.60Synovial giant cells0.58Sub-lining giant cells0.57Russell bodies0.56Germinal centers0.51Mucoid change0.50Figure 1.

Importance of synovial features in distinguishing RA and OA synovium

Feature importance scores for supervised machine learning model including all 14 pathology scores and the computer vision-generated cell density.

Conclusion

H&E-stained images of RA and OA TKR explant synovium are distinct. We identified cell density, mast cells and fibrosis as the three most important features for making this distinction, with RA being characterized by increased cell density, low mast cells, and low fibrosis. Cell density greater than 3400 per mm2 of tissue yields a sensitivity of 0.82 and a specificity of 0.82 for distinguishing RA from OA. In the future, this can have clinical and research applications as this technique removes the requirement for subjective selection of a certain field of interest, is reproducible, and is scalable as it does not require technical expertise of a pathologist.

References

[1]Guan S, Mehta B…Orange DE. Rheumatoid Arthritis Synovial Inflammation Quantification Using Computer Vision. ACR Open Rheumatology. 2022 Jan 10;acr2.11381.

Acknowledgements

This work was supported by the C. Ronald MacKenzie Young Scientist Endowment Award, the Leon Lowenstein Foundation, and the Kellen Scholar Award supported by the Anna Marie and Stephen Kellen Foundation Total Knee Improvement Program.

Disclosure of Interests

Bella Mehta Paid instructor for: Novartis, Susan Goodman Consultant of: UCB, Grant/research support from: Novartis, Edward DiCarlo: None declared, Deanna Jannat-Khah Shareholder of: AstraZeneca, Cytodyn, and Walgreens, J. Alex Gibbons: None declared, Miguel Otero Consultant of: Regeneron Pharmaceuticals, Grant/research support from: Tissue Genesis, Laura Donlin Speakers bureau: Stryker, Consultant of: Stryker, Grant/research support from: Karius, Inc, Tania Pannellini: None declared, William Robinson: None declared, Peter Sculco Consultant of: Intellijoint Surgical, DePuy Synthes, Lima Corporate, Zimmer Biomet, and EOS Imaging, Grant/research support from: Intellijoint Surgical and Zimmer Biomet, Mark Figgie Shareholder of: HS2, Mekanika, and Wishbone, Consultant of: Lima and Wishbone, Jose Rodriguez Consultant of: ConforMIS, Medacta, Exactech, Inc, and Smith & Nephew, Grant/research support from: DePuy, Exactech, Inc, and Smith & Nephew, Jessica Kirschmann: None declared, James Thompson: None declared, David Slater: None declared, Damon Frezza: None declared, Zhenxing Xu: None declared, Fei Wang: None declared, Dana Orange: None declared

Enhanced cell-associated plasminogen activator pathway but not coagulation pathway activity contributes to motility in metastatic breast cancer cells

BACKGROUND

Activation of tumor cell-associated coagulation and plasminogen activator pathways occurs in malignant disease processes, including breast cancer, and may promote metastatic activity.

OBJECTIVES/METHODS

To compare the coagulation and plasminogen activator pathways of normal and metastatic cells, we examined two cell lines from the MCF-10 family of breast cells: near-normal immortalized MCF-10A cells, and metastatic MCF-10CA1 cells.

RESULTS

MCF-10CA1 cell motility was significantly increased as compared with that of MCF-10A cells. The two cell types supported similar rates of factor Xa generation, plasma thrombin generation, and fibrin formation. MCF-10A cells produced a stable fibrin network, whereas MCF-10CA1 cells lysed the surrounding fibrin network within 24 h of network formation. Importantly, fibrin located proximal to (within 10 microm) the MCF-10CA1 cell surface lysed substantially faster than fibrin located 100 microm from the surface. MCF-10CA1 cells supported significantly increased plasmin generation rates as compared with MCF-10A cells, providing a mechanism for the increased fibrinolytic activity of these cells towards the fibrin network. Metastatic MCF-10CA1 cells had increased expression (mRNA and protein) levels of urokinase plasminogen activator (u-PA) and decreased levels of plasminogen activator inhibitor-1 as compared with MCF-10A cells. Blocking u-PA activity with the active site-directed protease inhibitor amiloride substantially decreased MCF-10CA1 cell motility. Phosphorylated Akt levels were elevated in MCF-10CA1 cells, which partially explains the increased u-PA expression.

CONCLUSIONS

These results suggest that the tumor-associated plasminogen activator pathway, not the coagulation pathway, is a key distinguishing feature between metastatic MCF10-CA1 cells and normal MCF-10A cells.

Cross-species comparisons of the pharmacokinetics of ibudilast

To enable clinical development of ibudilast for new indications, its pharmacokinetics were characterized in mice, rats, rabbits, dogs, cynomolgus monkeys, and minipigs. Animal pharmacokinetics were compared with a separate study in healthy volunteers. Following oral dosing, the dose-normalized area under the curve (AUC) (DN-AUC(24h)) in humans is 896 ((ng*h ml(-1))/(mg kg(-1))), and in animals ranges from 0.3 to 87. The variability among species cannot be explained by intrinsic clearance, which in intravenous dosing experiments shows only moderate interspecies variation (13-41 l h(-1) m(-2)). A portal vein rat pharmacokinetics model suggested that differences in first-pass gut clearance may explain some of the interspecies variation in oral bioavailability. Ibudilast shows auto-induction of metabolism in some animals, but not in humans. Plasma protein binding in humans and some animals is greater than or equal to 95%. The primary metabolite 6,7-dihyrdodiol-ibudilast is measurable and has been quantitated in plasma from animals and humans. Finally, biodistribution studies show that ibudilast distributes rapidly, extensively, and reversibly to the central nervous system.

A T-cell-selective interleukin 2 mutein exhibits potent antitumor activity and is well tolerated in vivo

Human interleukin 2 (IL-2; Proleukin) is an approved therapeutic for advanced-stage metastatic cancer; however, its use is restricted because of severe systemic toxicity. Its function as a central mediator of T-cell activation may contribute to its efficacy for cancer therapy. However, activation of natural killer (NK) cells by therapeutically administered IL-2 may mediate toxicity. Here we have used targeted mutagenesis of human IL-2 to generate a mutein with approximately 3,000-fold in vitro selectivity for T cells over NK cells relative to wild-type IL-2. We compared the variant, termed BAY 50-4798, with human IL-2 (Proleukin) in a therapeutic dosing regimen in chimpanzees, and found that although the T-cell mobilization and activation properties of BAY 50-4798 were comparable to human IL-2, BAY 50-4798 was better tolerated in the chimpanzee. BAY 50-4798 was also shown to inhibit metastasis in a mouse tumor model. These results indicate that BAY 50-4798 may exhibit a greater therapeutic index than IL-2 in humans in the treatment of cancer and AIDS.

Intestinal absorption screening of mixtures from combinatorial libraries in the Caco-2 model

PURPOSE

Understanding how chemical structures influence transport across the intestinal mucosa will greatly enhance the discovery of orally available drugs. In an attempt to accelerate defining such relationships between structure and transport, six arbitrary mixtures of N-substituted glycine (NSG) peptoids containing 24 physicochemically diverse compounds were evaluated in the Caco-2 model of intestinal absorption.

METHODS

Samples were analyzed by HPLC and the areas of the peaks representing the components of each mixture were summed to measure "aggregate" apparent permeability coefficients (Papp), a score of the influence of the common structural element within each mixture towards absorption. Mass spectrometry was used to identify the chemical structure of Caco-2 permeable compounds.

RESULTS

Three linear trimeric mixtures were examined and, for each mixture, none of the components was detected in receiver chambers. It was concluded that the components of these mixtures each had a Papp value less than 0.8 x 10(-6) cm/sec, a permeability less than mannitol. Three dimeric mixtures were examined and they exhibited aggregate P(app) values of 9.2 x 10(-6), 14 x 10(-6) and 6.9 x 10(-6) cm/sec. These transport rates reflected the transport of most of the components of each mixture. Furthermore, the components of the dimeric mixtures which were transported at a rate greater than mannitol were apparently transported by passive mechanisms.

CONCLUSIONS

This study demonstrated that mixtures can be used to study structure-transport relationships in the Caco-2 model. The information obtained from this type of study will be integrated into the design of future chemical libraries. Other potential uses of chemical mixtures with the Caco-2 model are also discussed.

Immunopharmacology and cytokine production of a low-dose schedule of intraperitoneally administered human recombinant interleukin-2 in patients with advanced epithelial ovarian carcinoma

We determined in the peritoneal cavity (p.c.) of epithelial ovarian carcinoma patients during a 4-day treatment cycle of low-dose recombinant human interleukin-2 (rIL-2): (a) pharmacokinetics of IL-2, (b) endogenous cytokine production, and (c) numbers and percentages of peritoneal exudate lymphocytes. We administered 6 x 10(5) IU/m2 of rIL-2 (0.03 mg/m2 Proleukin rIL-2) intraperitoneally (i.p.) over 30 min on each of 4 days. One and one-half liters of D5 0.25 NS was injected i.p. before each rIL-2 infusion. Multiple peritoneal fluid samples were obtained from each of four patients on day 1 and day 4 for detection of IL-2, endogenous cytokines, and soluble IL-2 receptor (IL-2R-alpha). IL-2 concentrations in the peritoneal fluid were determined by bioassay and interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, IL-10, transforming growth factor (TGF)-beta 2, and sIL-2R-alpha by enzyme-linked immunosorbent assay. Numbers of cells per microliter and lymphocyte subpopulation percentages after staining with a panel of monoclonal antibodies were determined on day 1, day 4, and subsequent off-treatment days. IL-2 disappearance in the p.c. was well described by a pharmacokinetic model having constant-rate infusion and biexponential disposition. About 90% of the IL-2 disappearance occurred during the beta-phase, during which IL-2 concentrations were sustained at approximately 10-30 ng/ml (day 1 and day 4) and the median t1/2 beta was 21.5 and 9.2 h on days 1 and 4, respectively. In four of four patients, p.c. production of IL-10 was observed on day 1 and day 4 (maximum 387 pg/ml). Maximum levels of IFN-gamma and sIL-2R-alpha were observed on day 4. (IFN-gamma 217 pg/ml; sIL2-R-alpha: 3486 U/ml). No increases in TNF-alpha or TGF-beta 2 were observed. Large increases in p.c. CD3+, CD4+, CD8+, CD16+, and CD56+ cells were observed. We conclude that biologically active levels of IL-2 are generated in p.c. fluids after i.p. administration of rIL-2 at 0.03 mg/m2.

Pharmacologic characterization of CHIR 2279, an N-substituted glycine peptoid with high-affinity binding for alpha 1-adrenoceptors

We characterize the in vitro and in vivo pharmacology of CHIR 2279, an N-substituted glycine peptoid previously identified from a combinatorial library as a novel ligand to alpha 1-adrenoceptors. Competitive receptor-binding assays with [3H]prazosin showed that CHIR 2279 was similar to prazosin in binding to alpha 1A (rat submaxillary), alpha 1a, alpha 1b, and alpha 1 d (cDNA expressed in LTK- cells) with high and approximately equipotent affinity. Ki values for CHIR 2279 ranged from 0.7 to 3 nM, and were 10-fold weaker than with prazosin. Functional assays for postsynaptic alpha 1-adrenoceptors showed CHIR 2279 was approximately equipotent in antagonizing agonist-induced contractile responses with rat was deferens (alpha 1A), canine prostate (alpha 1A), rat spleen (alpha 1B) and rat aorta (alpha 1D). The pA2 for CHIR 2279 averaged 7.07 in these assays, indicating a 10- to 100-fold lower in vitro potency than prazosin. In dogs, CHIR 2279 antagonized the epinephrine-induced increase in intraurethal pressure (pseudo pA2, 6.86) and in rats antagonized the phenylephrine-induced increase in mean arterial blood pressure. In rats and guinea pigs, CHIR 2279 induced a dose-dependent decrease in mean arterial blood pressure without eliciting the tachycardia commonly observed with other alpha 1-blockers. Pharmacokinetic/pharmacodynamic modeling showed the i.v. system clearance rate of CHIR 2279 was 60 and 104 ml/min/kg in rats and guinea pigs, respectively, and the in vivo potency for mean arterial blood pressure reduction was twice as great in guinea pigs (EC50, 520 ng/ml) than rats (EC50, 1170 ng/ml).

Quantitation of the renal clearance of interleukin-2 using nephrectomized and ureter-ligated rats

The objective of this work was to determine the role of the kidneys in the systemic clearance rate (CL) of interleukin-2 (IL-2). Rats received IL-2 by i.v. bolus and the pharmacokinetic data were found to be well described by a two-compartment, first-order elimination model. With administration of 0.2, 0.5 or 1.0 mg/kg of IL-2 (n = 3 per treatment), the median alpha and beta half-lives (T1/2 alpha, 2.3 min; T1/2 beta, 13.2 min, respectively), initial volume of distribution (V1, 93 ml/kg), volume of distribution at steady state (Vss, 198 ml/kg) and CL (16.8 ml min-1 kg-1) did not vary with the dose (P = .05). This demonstration of first-order kinetics suggested that renal CL remains constant over a range of doses. The pharmacokinetic properties of 1.0 mg/kg of IL-2 were examined after either single or double nephrectomy (n = 3 and 4, respectively), sham operation (n = 4) or no renal operation (n = 4; the "controls"). No difference in median T1/2 alpha, T1/2 beta, V1, Vss or CL was detected between control and sham-operated rats nor between single nephrectomy and sham operation. Compared with sham operation, double nephrectomy showed no significant change in V1 or Vss but the T1/2 alpha and T1/2 beta approximately doubled and CL was reduced by 75%. In a separate experiment, ureter-ligated rats were compared with sham-operated rats. With ureter ligation, T1/2 alpha, T1/2 beta, V1 and Vss were unchanged but CL was reduced by 36%.

Venovenous extracorporeal life support in traumatic bronchial disruption and adult respiratory distress syndrome using surface-heparinized equipment: case report

Venovenous extracorporeal membrane oxygenation and carbon dioxide removal was utilized to support a patient with traumatic bronchial disruption and associated injuries. With use of surface-heparinized perfusion equipment, low levels of anticoagulation were maintained allowing surgical repair of the bronchial injury and recovery from acute respiratory failure without significant hemorrhage.

Nonlinear pharmacokinetics of recombinant human macrophage colony-stimulating factor (M-CSF) in rats

The pharmacokinetics and mechanisms of elimination of recombinant human macrophage-colony stimulating factor (M-CSF) were investigated in rats. Intravenous injections of 0.1, 1 or 10 mg/kg M-CSF were administered and plasma samples were measured for M-CSF by bioassay. Systemic clearance decreased and the shape of the concentration-time curve changed with increasing dose, indicating nonlinear pharmacokinetics. At 10 mg/kg, two half-lives were initially observed, but after about 20 hr the plasma M-CSF suddenly declined with a steep slope. The rapidly declining phase suggested a saturable clearance mechanism that was prominent at low plasma concentrations of M-CSF (below 300 ng/ml) and obscured at high plasma concentrations of M-CSF. The rapid decline of plasma M-CSF occurred at earlier times with multiple daily injections of M-CSF, indicating induction of the saturable clearance mechanism. The rapidly declining phase was inhibited by carrageenan, indicating that saturable clearance might be due to metabolism of M-CSF by macrophages. With ligation of either the renal pedicles or ureters, the apparent half-lives of M-CSF increased by a factor of 2- to 3-fold, while the occurrence of the rapidly declining phase was delayed, but not eliminated. Overall, the results are well described by a two-compartment, first-order elimination model with a parallel Michaelis-Menten elimination pathway. First-order elimination is largely performed by the kidneys and the saturable Michaelis-Menten elimination pathway appears to be mediated by cells of the monocyte-macrophage lineage.

Phase I trial of subcutaneous recombinant macrophage colony-stimulating factor: clinical and immunomodulatory effects

PURPOSE

Recombinant human macrophage colony-stimulating factor (rM-CSF) has been demonstrated to control the growth, differentiation, and function of mononuclear phagocytes. Preclinical studies have indicated antitumor effects, and therefore a phase I trial of rM-CSF in patients with malignancy was initiated. The toxicity and hematologic and immunologic effects were investigated.

PATIENTS AND METHODS

rM-CSF was administered as a subcutaneous injection on days 1 through 5 and 8 through 12. Cycles were repeated every 28 days. Cohorts of four to seven patients received rM-CSF at dose levels from 0.1 to 25.6 mg/m2/d. Forty-two patients received 88 cycles of rM-CSF. All patients had metastatic solid tumors refractory to standard therapy.

RESULTS

The toxicity of rM-CSF was mild. Dose-limiting toxicity included thrombocytopenia (two patients) and iritis (one patient) occurring at a dose of 25.6 mg/m2/d. Hematologic studies demonstrated dose-related monocytosis occurring routinely at doses > or = 3.2 mg/m2/d, and thrombocytopenia. Immunologic studies demonstrated enhanced secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta) by monocytes after in vitro stimulation with lipopolysaccharide, and increased expression of TNF-alpha mRNA at higher rM-CSF dose levels. Pharmacokinetic studies demonstrated that the systemic clearance rate of M-CSF increases during week 1 of therapy, resulting in lower blood levels of M-CSF during the second week of therapy.

CONCLUSION

rM-CSF can be safely administered to patients, and has biologic activity on peripheral-blood monocytes.

Benzo[e]pyrene elicits changes in the biochemical activities and chromatographic behavior of murine hepatic cytochromes P-450 that are distinct from those induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin

The objective of this study was to examine the potential for a specific ligand of carcinogen binding protein (CBP) to induce changes in the overall character of hepatic microsomal cytochromes P-450 (P450) and to compare potential changes with those induced by an Ah receptor ligand. Benzo[e]pyrene (BeP) was previously shown to bind CBP with high affinity and Ah receptor with low affinity. In contrast, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) binds Ah receptor avidly and CBP weakly. Hepatic microsomes were prepared from C57BL/6J (B6) and DBA/2J (D2) mice treated with corn oil, BeP or TCDD. Relative to corn oil controls, pretreatment of B6 mice with BeP or TCDD increased the nmol P450/mg microsomal protein content 26 and 28%, respectively. In D2 mice, nmol P450/mg microsomal protein was increased 23% in the BeP pretreatment, while TCDD pretreatment had no effect relative to the corn oil controls. For the O-alkyl ethers of resorufin, rates of metabolism (per nmol P450) were affected differently in B6 and D2 by BeP pretreatment. Pentoxyresorufin O-dealkylase activity was reduced to 44% of control activity in B6 mice and increased 39% relative to controls in D2 mice. BeP pretreatment had no effect on ethoxyresorufin O-dealkylase activity in B6 mice, while this activity was decreased to 58% of controls in D2 mice. Additionally, benzyloxyresorufin O-dealkylase activity was reduced to 65% of control levels in B6 mice and not affected in D2 mice. Methoxyresorufin O-dealkylase activity was reduced in both strains to an average of 55% of control values. As expected, TCDD pretreatment resulted in increases of all O-dealkylations measured in both strains of mouse. For both inbred strains of mouse, anion exchange chromatography revealed a P450 peak associated with BeP pretreatment that was not present in chromatograms generated with corn oil or TCDD pretreatments. Results of enzyme linked immunosorbant assays also indicated that the pattern of P450 isoenzyme expression associated with BeP pretreatment was distinct from that associated with TCDD pretreatment. Overall, these data show that treatment with a specific ligand of CBP induces changes the biochemical activities and chromatographic behavior of P450 isozymes in murine hepatic microsomes. Moreover, they indicate that changes in P450 occurring after treatment with a CBP ligand are distinct from those changes that are associated with treatment with an Ah receptor ligand (TCDD). Differences between B6 and D2 strains suggest that the hepatic P450 changes occurring in response to pretreatment with a CBP ligand may be influenced by the presence of Ah receptor.

Benzo[e]pyrene pretreatment of immature, female C57BL/6J mice results in increased bioactivation of aflatoxin B1 in vitro

Hepatic microsomes were prepared from immature C57BL/6J mice 24 h after receiving intraperitoneal injections of either corn oil, benzo[e]pyrene (BeP, 50 mg/kg) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 4 x 10(-3) mg/kg). The capacity of these hepatic microsomes to bioactivate aflatoxin B1 (AFB1), 2-aminoanthracene (AA), benzo[a]pyrene (BaP), 3-methylcholanthrene (MC), 7,12-dimethylbenzanthracene (DMBA), BeP and pyrene (PY) was measured using strain TA100 in the Salmonella typhimurium/microsome reversion assay. BeP pretreatment of mice resulted in a 33% increase in mutagenic potency (MP) of AFB1 over the corn oil controls and a 70% increase in MP relative to TCDD-pretreated microsomes. With AA, BaP and DMBA as promutagens, BeP pretreatment reduced MP an average of 24%, while TCDD pretreatment increased MP of these 3 promutagens 263% compared to controls. Since the general effects of BeP and TCDD on murine hepatic cytochrome P-450 (P450)-mediated activities in this study were discordant, it appears that changes in P450 activity by BeP pretreatment are not mediated through the Ah receptor.

Halothane and isoflurane only slightly impair arterial oxygenation during one-lung ventilation in patients undergoing thoracotomy

Controversy exists as to whether the halogenated inhalation (IH) anesthetics impair arterial oxygenation during one-lung ventilation (1-LV). Accordingly, the authors have answered this question in 12 consenting patients who required 1-LV to facilitate the performance of thoracic surgery, by comparing arterial oxygenation during a prolonged period of IH anesthesia with arterial oxygenation during a prolonged period of intravenous (IV) anesthesia during stable 1-LV conditions. The patients were equally divided into halothane and isoflurane groups. Each patient in each IH anesthetic group underwent the following experimental sequence: step 1, two-lung ventilation (2-LV), 1 MAC IH anesthesia; step 2, 1-LV, 1 MAC IH anesthesia; step 3, 1-LV, iv anesthesia; step 4, 2-LV, iv anesthesia. Stable 1-LV conditions were proven by serial arterial blood gas measurement. Conversion from 2-LV to 1-LV during IH anesthesia (step 1 to step 2) caused a very large and significant decrease in PaO2 (from 484 +/- 49 to 116 +/- 61, and from 442 +/- 58 to 232 +/- 97 mmHg in the halothane and isoflurane groups, respectively) and increase in shunt (from 14 +/- 4 to 44 +/- 9, and from 19 +/- 5 to 31 +/- 8% in the halothane and isoflurane groups, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized tomographic diagnosis of paracardiac masses

Paracardiac masses may alter the cardiac contour seen on roentgenograms of the chest so as to mimic configurations associated with cardiac disease. Recently, the use of computerized transmission tomography has proved valuable as a noninvasive method of distinguishing between intrinsic cardiac disease and paracardiac masses. In some cases, the procedure obviates the need for preoperative cardiac catheterization.

A comparison of synthetic absorbable suture with synthetic nonabsorbable suture for construction of tracheal anastomoses

This study compares the use of synthetic absorbable suture (SAS, Vicryl) with that of synthetic nonabsorbable suture (SNS, Ticron) for construction of cervical tracheal anastomoses in the dog. Fourteen mongrel dogs underwent resection of one to four tracheal rings. Paired tracheal anastomoses were constructed, using 10 SAS or 10 SNS. After two months each anastomosis was removed and analyzed. All animals survived with intact anastomoses. There were no visible reactions to the SAS. Twenty-six of 70 SNS developed gross suture granulations. Significant stenosis developed in one of seven SAS and in four of seven SNS anastomoses. Histologic examination revealed no residual inflammatory reaction in the SAS specimens, while the SNS demonstrated a spectrum of inflammatory response that directly correlated in intensity with the gross appearance. These findings support the continued evaluation for the use of SAS in clinical tracheobronchoplastic procedures.

Dressler's syndrome and angina pectoris relieved by surgery

A 49-year-old woman with progressive angina pectoris developed chronic Dressler's syndrome following a second myocardial infarction. Control of the chronic pericarditis required long-term steroid therapy. Because of multiple complications generated by the steroid administration, she underwent coronary angiography followed by pericardiectomy and coronary artery bypass surgery. The patient remains asymptomatic without steroid or antianginal medication five years after surgery.

The recessed chest wall pacemaker pocket

Recurrent pouch problems led to the development of a recessed chest wall pacemaker pocket. Segments of the seventh and eighth ribs were resected in the mid-axillary line resulting in a "tailor-made" space suitable for generator implantation. Follow-up at one year has proven the chest wall to be a satisfactory alternative site for a pacemaker pocket.

An analysis of direct and indirect measurements of left atrial filling pressure

Left ventricular function may be assessed by direct catheter measurements of left atrial pressure or by indirect measurements of pulmonary artery wedge pressure or pulmonary artery end-diastolic pressure. Controversy exists as to how closely the indirect measurements correlate with true left atrial pressure and to which is the most accurate. To clarify this probelm, we studied 43 patients undergoing cardiac surgical procedures with cardiopulmonary bypass. Both left atrial catheters for direct measurement and Swan-Ganz catheters were placed at the time of surgery. All patients were monitored continuously for 48 hours and hourly measurements were recorded. The resultant 1,620 left atrial pressure and pulmonary artery wedge pressure figures and 1,860 left atrial pressure and pulmonary artery end-diastolic wedge pressure measurements were subjected to computer analysis. The following conclusions have been found: (1) Pulmonary artery wedge pressure is a better indirect measure of left atrial pressure than is pulmonary artery end-diastolic wedge pressure (pooled correlation coefficient 0.629); (2) direct left atrial pressure measurement is more reliable and has fewer complications than indirect measurements; (3) there is no consistent correlation between left atrial pressure and central venous pressure (pooled correlation coefficient 0.3). A discussion of our results and the problems associated with left atrial catheters and Swan-Ganz catheters is presented.