Developing a pathway for high-value, patient-centered total joint arthroplasty

BACKGROUND

Total joint arthroplasty (TJA) is one of the most widely performed elective procedures; however, there are wide variations in cost and quality among facilities where the procedure is performed.

QUESTIONS/PURPOSES

The purposes of this study were to (1) develop a generalizable clinical care pathway for primary TJA using inputs from clinical, academic, and patient stakeholders; and (2) identify system- and patient-level processes to provide safe, effective, efficient, and patient-centered care for patients undergoing TJA.

METHODS

We used a combination of quantitative and qualitative methods to design a care pathway that spans 14 months beginning with the presurgical office visit and concluding 12 months after discharge. We derived care suggestions from interviews with 16 hospitals selected based on readmission rates, cost, and quality (n = 10) and author opinion (n = 6). A 32-member multistakeholder panel refined the pathway during a 1-day workshop. Participants were selected based on leadership in orthopaedic (n = 4) and anesthesia (n = 1) specialty societies; involvement in organizations specializing in safety and high reliability care (n = 3), lean production/consumption of care (n = 3), and patient experience of care (n = 3); membership in an interdisciplinary care team of a hospital selected for interviewing (n = 8); recent receipt of a TJA (n = 1); and participation in the pathway development team (n = 9).

RESULTS

The care pathway includes 40 suggested processes to improve care, 37 techniques to reduce waste, and 55 techniques to improve communication. Central themes include standardization and process improvement, interdisciplinary communication and collaboration, and patient/family engagement and education. Selected recommendations include standardizing care protocols and staff roles; aligning information flow with patient and process flow; identifying a role accountable for care delivery and communication; managing patient expectations; and stratifying patients into the most appropriate care level.

CONCLUSIONS

We developed a multidisciplinary clinical care pathway for patients undergoing TJA based on principles of high-value care. The pathway is ready for clinical testing and context-specific adaptation.

LEVEL OF EVIDENCE

Level V, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

The role of nursing home admission and dementia status on care for diabetes mellitus

OBJECTIVES

To study the role of nursing home (NH) admission and dementia status on the provision of five procedures related to diabetes mellitus.

DESIGN

Retrospective cohort study using data from a large prospective study in which an expert panel determined the prevalence of dementia.

SETTING

Fifty-nine Maryland NHs.

PARTICIPANTS

Three hundred ninety-nine new admission NH patients with diabetes mellitus.

MEASUREMENTS

Medicare administrative claims records matched to the NH medical record data were used to measure procedures related to diabetes mellitus received in the year before NH admission and up to a year after admission (and before discharge). Procedures included glycosylated hemoglobin, fasting blood glucose, dilated eye examination, lipid profile, and serum creatinine.

RESULTS

For all but dilated eye examinations, higher rates of procedures related to diabetes mellitus were seen in the year after NH admission than in the year before. Residents without dementia received more procedures than those with dementia, although this was somewhat attenuated after controlling for demographic, health, and healthcare utilization variables. Persons without dementia experience greater increases in procedure rates after admission than those with dementia.

CONCLUSION

The structured environment of care provided by the NH may positively affect monitoring procedures provided to elderly persons with diabetes mellitus, especially those without dementia. Medical decisions related to the risks and benefits of intensive treatment for diabetes mellitus to patients of varying frailty and expected longevity may lead to lower rates of procedures for residents with dementia.

Treatment approach and HbA1c control among US adults with type 2 diabetes: NHANES 1999-2004

OBJECTIVE

To examine the distribution of diabetic medications among adults with type 2 diabetes, and the association between glucose control and treatment approach in the US population.

METHODS

Interview and prescription medication data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) were used to determine the treatment approach for US adults with type 2 diabetes. Mean glycosylated hemoglobin (HbA1c) and the proportion of adults meeting recommended guidelines for glucose control were estimated for each treatment approach. The most important study limitation was that participants were not asked what type of diabetes they had. Among adults with diabetes, a classification algorithm was used to identify those with type 2 diabetes.

RESULTS

During 1999-2004, approximately 60% of adults with type 2 diabetes used oral agents only to manage their diabetes. The distribution of oral treatment therapies changed over time (p < 0.01); the most prevalent treatment shifted from sulfonylurea monotherapy in 1999-2000 (23.0%) to any oral agent regimen containing thiazolidinedione (TZD) in 2003-2004 (21.4%). Overall, only 52.2% of adults with type 2 diabetes met the American Diabetes Association (ADA) goal for HbA1c control (<7.0%) during 1999-2004. Across oral agent treatment categories, the proportion with HbA1c controlled at the 7.0 level was significantly lower (p < 0.01) for those on triple therapy (31.9%) (TZD, sulfonylurea, and metformin), than those on metformin alone (62.2%), likely reflecting a progressive treatment approach of prescribing additional medications for those with uncontrolled HbA1c levels.

CONCLUSIONS

Use of multiple oral agents among adults with type 2 diabetes has increased (sulfonylurea and metformin, p = 0.03, triple therapy, p = 0.02). However, nearly half of adults with type 2 diabetes have HbA1c levels above ADA guidelines for control, indicating that available treatments could be used more optimally, and new diabetic agents may be needed.

Where do I send thee? Does physician-ownership affect referral patterns to ambulatory surgery centers?

For more than three decades, Congress has struggled with potential financial conflicts of interest when physicians share in financial gain from nonprofessional services. This study asks the question: Are physicians who are leading referrers to physician-owned ambulatory surgery centers (ASCs) more likely to send Medicaid patients to hospital outpatient clinics than other patients? The comparison group is physicians who are leading referrers to non-physician-owned ASCs, using data from two metropolitan areas. Findings indicate that physicians at physician-owned facilities are more likely than other physicians to refer well-insured patients to their facilities and route Medicaid patients to hospital outpatient clinics.

Potentially Inappropriate Medication Use by Medicaid+Choice Beneficiaries in the Last Year of Life

BACKGROUND

Regardless of the payer and the period studied the prevalence of potentially inappropriate medication use in the elderly ranged from 21% to 40%.

OBJECTIVE

To look at potentially inappropriate prescribing in a group of Medicare+Choice beneficiaries in their last year of life (LYOL) in a large national managed care organization.

RESEARCH DESIGN

Retrospective review of Medicare+Choice decedents' drug claims and enrollment data collected between January 1998 and December 2000, supplemented by the Medicare denominator file and 1990 Census data.

SUBJECTS

Four thousand six hundred two beneficiaries in a large national managed care organization.

MEASURES

We analyzed the relationship between disagreement with the Beers' criteria and sociodemographic descriptors, insurance characteristics, and cause of death. We used logistic regression techniques to estimate factors associated with the disagreement.

RESULTS

Two thousand thirty-one beneficiaries (44%) had at least one claim in the LYOL that disagreed with a Beers' criterion, 15% experienced more than one unique Beers' disagreement. The most common disagreements were for the use of propoxyphene (15.0%), followed by zolpidem (3.8%), and amitriptyline (2.8%). Based on total claims, cancer patients were most likely to receive propoxyphene (35.3%) followed by patients with a heart condition (29.6%). A large proportion of the potentially inappropriate prescribing involves psychoactive drugs. The logistic model showed fewer Beers' criteria breaches associated with being male and being non-white. Beers' breaches were more common if the beneficiary has increasing prescription use or died from cancer.

CONCLUSION

This study showed that many beneficiaries have prescriptions that contravene the Beers' criteria.

Physicians' experiences using commercial e-prescribing systems

Public and private efforts are under way to promote electronic prescribing to improve health care safety, quality, and efficiency. Findings from this qualitative study of physician practices suggest that substantial gaps may exist between advocates' vision of e-prescribing and how physicians use commercial e-prescribing systems today. While physicians were positive about the most basic e-prescribing features, they reported major barriers to maintaining complete patient medication lists, using clinical decision support, obtaining formulary data, and electronically transmitting prescriptions to pharmacies. Three factors help explain the gaps: product limitations, external implementation challenges, and physicians' preferences about using specific product features.

Prescription drug spending for Medicare+Choice beneficiaries in the last year of life

BACKGROUND

In 2006, Medicare implemented its prescription benefit plan. Therefore, insights into medication costs at the end of life may help guide clinicians to navigate Medicare Part D coverage for chronically ill individuals.

OBJECTIVES

We examined drug spending by disease and demographics for Medicare+Choice (M+C) beneficiaries in the last year of life (LYOL).

RESEARCH DESIGN

Retrospective review of M+C decedents' drug claims and enrollment data collected between January 1998 and December 2000, supplemented by the Medicare denominator file and 1990 Census data.

SUBJECTS

Four thousand six hundred two beneficiaries in a large national managed care organization.

MEASURES

We analyzed the relationship between prescription drug expenditures and sociodemographic descriptors, insurance characteristics, and cause of death.

RESULTS

The mean annual number of prescriptions filled was 36.9; the managed care organization (MCO) paid $539 and beneficiaries paid $627. Higher expenditures were significantly correlated with female gender, higher number of comorbidities, and whether beneficiaries obtained the insurance as an employer-based retiree benefit. Minority beneficiaries had 26% fewer prescriptions. Increasing levels of annual median household income corresponded with a 20% increase in the number of prescriptions and a 25% increase in mean out-of-pocket expenses, between those with a median household income of less than $20,000 and those with $40,000 or greater. In the LYOL, chronic obstructive pulmonary disease and diabetes had the highest average number of prescriptions and total expenditures. Individuals dying from strokes or other unclassifiable conditions had the lowest average number of prescriptions and average total expenditures.

CONCLUSION

Medication expenditures in the LYOL were highly dependent upon selected sociodemographic, insurance characteristics, and disease states.

Generosity And Adjusted Premiums In Job-Based Insurance: Hawaii Is Up, Wyoming Is Down

This paper reports national and state findings on the generosity or actuarial value of U.S. employer-based plans and adjusted premiums in 2002. The basis for our calculations is simulated bill paying for a large standardized population. After adjusting for the quality of benefits, we find from regression analysis that adjusted premiums are 18 percent higher in the nation's smallest firms than in firms with 1,000 or more workers. They are 25 percent higher in indemnity plans and 18 percent higher in preferred provider organizations than in health maintenance organizations. The generosity of coverage increased from 1997 to 2002.

Medicare cost differences between nursing home patients admitted with and without dementia

PURPOSE

Our objective in this study was to compare Medicare costs of treating older adults with and without dementia in nursing home settings.

DESIGN AND METHODS

An expert panel established the dementia status of a stratified random sample of newly admitted residents in 59 Maryland nursing homes between 1992 and 1995. Medicare expenditures per-person month (PPM) were compared for 640 residents diagnosed with dementia and 636 with no dementia for 1 year preadmission and 2 years postadmission. Multivariate analysis with generalized estimating equations was used to identify the source of Medicare cost differentials between the two groups.

RESULTS

Medicare expenditures peaked in the month immediately preceding admission and dropped to preadmission levels by the third month in a nursing home. Adjusted PPM costs postadmission for the dementia group as a whole were 79% (p < .001) of the Medicare costs of treating residents without dementia. For the subgroup of residents admitted without a Medicare qualified stay (MQS), those with dementia had Medicare costs of just 63% (p < .001) of those without dementia. Overall Medicare costs PPM were insignificantly different between the two groups admitted with a MQS.

IMPLICATIONS

Whether nursing home residents are admitted with a MQS is the single most important factor in assessing treatment cost differentials between residents admitted with and without dementia. Failure to consider this factor may lead researchers and policy makers to misdirect their attention from the true source of the differential-dementia patients admitted without a qualifying stay.

Employer-Sponsored Health Insurance And Prescription Drug Coverage For New Retirees: Dramatic Declines In Five Years

Employer-sponsored health insurance is often described as the most reliable private source of Medicare supplementation, particularly for prescription drug benefits. This study's findings show that employer coverage is becoming an increasingly less dependable source of coverage for new retirees, and the problem is likely to get worse. We found that the proportion of Medicare beneficiaries ages 65-69 with employer coverage declined from 46 percent in 1996 to 39 percent in 2000. The proportion with drug coverage from an employer declined from 40 percent in 1996 to 35 percent in 2000. Losses among males, the group most affected, would have been even greater had it not been for a slight increase in benefits from spouses' policies.

Community pharmacist knowledge and behavior in collecting drug copayments from Medicaid recipients

Community pharmacists' knowledge and behavior regarding the collection of copayments for prescription drugs from Medicaid recipients were studied. In fall 1998 a questionnaire was mailed to a random sample of 1465 community pharmacists (one pharmacist per drugstore) in Maryland, Pennsylvania, and West Virginia. The objectives were to determine the extent to which these pharmacists waived copayments for prescription drugs for Medicaid recipients, to document the pharmacists' knowledge of federal policies on Medicaid copayments, and to evaluate the factors associated with pharmacist copayment collection and knowledge of federal copayment policies. A total of 543 pharmacists (37%) responded. Most respondents indicated that they collected copayments for over 90% of drugs dispensed to Medicaid patients subject to copayment policies. Pharmacists most likely to waive Medicaid copayments practiced in drugstores with a high volume of Medicaid-related prescriptions and a large percentage of customers who were elderly Medicaid recipients. Pharmacists least likely to waive copayments believed that doing so would have a negative financial impact on the pharmacy. Nearly three fourths of the pharmacists exhibited fair or good knowledge of federal Medicaid copayment policies, but this varied widely by state. Many said that they would collect copayments in at least some situations even if this opposed federal policy. Pharmacists in Maryland, Pennsylvania and West Virginia had highly variable behavior patterns and knowledge with respect to the collection of drug copayments from Medicaid recipients.

Lentiviral gene transfer into primary and secondary NOD/SCID repopulating cells

The ability of lentiviral vectors to transfer genes into human hematopoietic stem cells was studied, using a human immunodeficiency virus 1 (HIV-1)-derived vector expressing the green fluorescence protein (GFP) downstream of the phosphoglycerate kinase (PGK) promoter and pseudotyped with the G protein of vesicular stomatitis virus (VSV). High-efficiency transduction of human cord blood CD34(+) cells was achieved after overnight incubation with vector particles. Sixteen to 28 percent of individual colony-forming units granulocyte-macrophage (CFU-GM) colonies derived from cord blood CD34(+) cells were positive by polymerase chain reaction (PCR) for the GFP gene. The transduction efficiency of SCID-repopulating cells (SRC) within the cord blood CD34(+) population was assessed by serial transplantation into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. When 400,000 cord blood CD34(+) cells were transplanted into primary recipients, all primary and secondary recipients contained and expressed the transgene. Over 50% of CFU-GM colonies derived from the bone marrow of these primary and secondary recipients contained the vector on average as determined by PCR. Transplantation of transduced cells in limiting dilution generated GFP(+) lymphoid and myeloid progeny cells that may have arisen from a single SRC. Inverse PCR analysis was used to amplify vector-chromosomal junctional fragments in colonies derived from SRC and confirmed that the vector was integrated. These results show that lentiviral vectors can efficiently transduce very primitive human hematopoietic progenitor and stem cells. (Blood. 2000;96:3725-3733)

Lentivirus vector gene expression during ES cell-derived hematopoietic development in vitro

The murine embryonal stem (ES) cell virus (MESV) can express transgenes from the long terminal repeat (LTR) promoter/enhancer in undifferentiated ES cells, but expression is turned off upon differentiation to embryoid bodies (EBs) and hematopoietic cells in vitro. We examined whether a human immunodeficiency virus type 1-based lentivirus vector pseudotyped with the vesicular stomatitis virus G protein (VSV-G) could transduce ES cells efficiently and express the green fluorescent protein (GFP) transgene from an internal phosphoglycerate kinase (PGK) promoter throughout development to hematopoietic cells in vitro. An oncoretrovirus vector containing the MESV LTR and the GFP gene was used for comparison. Fluorescence-activated cell sorting analysis of transduced CCE ES cells showed 99.8 and 86.7% GPF-expressing ES cells in the VSV-G-pseudotyped lentivirus (multiplicity of infection [MOI] = 59)- and oncoretrovirus (MOI = 590)-transduced cells, respectively. Therefore, VSV-G pseudotyping of lentiviral and oncoretrovirus vectors leads to efficient transduction of ES cells. Lentivirus vector integration was verified in the ES cell colonies by Southern blot analysis. When the transduced ES cells were differentiated in vitro, expression from the oncoretrovirus LTR was severely reduced or extinct in day 6 EBs and ES cell-derived hematopoietic colonies. In contrast, many lentivirus-transduced colonies, expressing the GFP gene in the undifferentiated state, continued to express the transgene throughout in vitro development to EBs at day 6, and many continued to express in cells derived from hematopoietic colonies. This experimental system can be used to analyze lentivirus vector design for optimal expression in hematopoietic cells and for gain-of-function experiments during ES cell development in vitro.

Low level of gene transfer to and engraftment of murine bone marrow cells from long-term bone marrow cultures

OBJECTIVE

We wanted to determine whether the long-term bone marrow culture (LTBMC) transduction system would lead to efficient gene transfer and engraftment of murine repopulating hematopoietic stem cells (HSC), particularly in nonablated recipients.

MATERIALS AND METHODS

Congenic mouse strains expressing Ly 5.1 or Ly 5.2 and the GP+E86 cell line producing the MGirL22Y vector carrying the gene for enhanced GFP were used. Murine LTBMCs were established and demi-depopulated on days 7 and 14 with addition of vector supernatant on days 8 and 15.

RESULTS

Cell recovery on day 21 was 21.3%+/-3.8% of input cells and CFU-C recovery was 9.7+/-3.4% as compared with CFU-C of input cells. In vitro transduction efficiency determined by CFU-C expressing GFP was 22.2%+/-1.6%. In irradiated (950 cGy) mice transplanted with 2x10(6) LTBMC cells, 94% of nucleated cells in the blood at week 16 were of donor origin. However, GFP was only detected at low level in a few animals at week 4 and not later. Analysis of bone marrow from these mice at week 20 did not show any GFP expression and semiquantitative PCR revealed a transgene level of <1%. When 3.5-20.8x10(6) LTBMC cells (corresponding to 20-100x10(6) fresh cells) were transplanted to nonablated recipients, no engraftment or GFP expression were detected. Competitive repopulation experiments showed that the long-term repopulation ability (LTRA) of the LTMC cells was only 7% of fresh cells.

CONCLUSION

These results indicate that LTBMC transduction of murine cells leads to low-level transduction of progenitors, no gene transfer to repopulating stem cells, and reduction in LTRA in ablated and nonablated recipients.

Outcomes of prospective drug-use review of beta-agonist inhaler use in an elderly Medicaid population

In 1990 Congress mandated that all state Medicaid programs implement both retrospective and prospective drug-use review (DUR). Nearly a decade later, implementation of prospective DUR (ProDUR) remains incomplete, and few of the implemented systems have been rigorously evaluated. This study was undertaken to analyze the impact of ProDUR screening of beta-agonist inhaler use in the Maryland Medicaid program from 1994 through 1996. The study used a pre/postcomparison series cohort design with data from Maryland, Georgia, and Iowa. Regression analysis was used to control for population differences between states in the year before the ProDUR intervention. The analysis used Medicaid and Medicare enrollment and claims data to select the study cohorts, assess exposure to the ProDUR intervention, develop patient risk profiles, and tabulate rates of adverse clinical outcomes for each subject. The study compared incidence rates for adverse outcomes for 2 1/2 years after implementation of the beta-agonist screens in Maryland, Georgia, and Iowa. Descriptive time plots and regression models were used to test the hypothesis that ProDUR screening reduces the incidence of adverse effects associated with misuse of beta-agonist inhalers. The study end points included 10 clinical outcomes related to therapeutic duplication and drug-drug interactions involving beta-agonist inhaler use by elderly individuals with chronic lung disease. No significant changes in the incidence of these outcomes could be linked to ProDur screening.

Correction of peripheral lysosomal accumulation in mice with aspartylglucosaminuria by bone marrow transplantation

OBJECTIVE

Bone marrow transplantation has been shown to alleviate symptoms outside the CNS in many lysosomal storage diseases depending on the type and stage of the disease, but the effect on neurological symptoms is variable or still unclear. Aspartylglucosaminuria (AGU) is a lysosomal storage disease characterized by mental retardation, recurrent infections in childhood, hepatosplenomegaly and coarse facial features. Vacuolized storage lysosomes are found in all tissues of patients and uncleaved enzyme substrate is excreted in the urine. The recently generated AGU mouse model closely mimicks the human disease and serves as a good model to study the efficiency of bone marrow transplantation in this disease.

METHODS

Eight-week-old AGU mice were lethally irradiated and transplanted with bone marrow from normal donors. The AGA enzyme activity was measured in the liver and the brain and the degree of correction of tissue pathology was analyzed by light and electron microscopy. Reverse bone marrow transplantation (AGU bone marrow to wild-type mice) was also performed.

RESULTS

Six months after transplantation the AGA enzyme activity was 13% of normal in the liver, but only 3% in the brain. Tissue pathology was reversed in the liver and the spleen, but not in the brain and the kidney. The urinary excretion of enzyme substrate was diminished but still detectable. No storage vacuoles were found in the tissues after reverse transplantation, but subtle excretion of uncleaved substrate was detected in the urine.

CONCLUSION

Liver and spleen pathology of AGU was corrected by bone marrow transplantation, but there was no effect on lysosomal accumulation in the CNS and in the kidneys.

Synthetic, implantable, biodegradable polymers for controlled release of radiosensitizers

INTRODUCTION

Synthetic, implantable, biodegradable polymers offer the sustained local release of disparate therapeutic agents for the treatment of human malignant brain tumors. The role of polymeric devices for the local delivery of radiosensitizers remains unexplored, however. We therefore quantified the release of the representative radiosensitizers IUdR (5-iodo-2'-deoxyuridine), tirapazamine (3-amino-1,2,4-benzotriazine-1,4-dioxide) and etanidazole [N-(2-hydroxyethyl)-2-nitro-1-imidazole-1-acetamide] from the [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) (PCPP:SA ratio 20:80)] polymer.

METHODS

For measurements of controlled release, triplicate polymer discs were incubated for known intervals in 2 ml 0.1 phosphate-buffered saline, pH 7.4, 37 degrees C. Using a predefined schedule, the supernatant fractions were systematically removed and replaced with fresh solution. The supernatant fractions were measured. The cumulative percentage of the loaded drug that appeared in these serial supernatant fractions was plotted vs. time. The percentage of the drug that was loaded into each polymer and that was released vs. time was fit to the power function of the form y = (a) x tb, where y is the cumulative released agent, a and b are constants and t is time (days).

RESULTS

The IUdR was released over an interval of approximately one week, while the release of the tirapazimine persisted for over 100 days. The etanidazole was released most rapidly, over a period of hours. Modeling of release showed that regardless of percentage loading of the drug, the monoexponential function showed high correlation of the fit of the plot of the release vs. time.

CONCLUSIONS

These results suggest that the hydrophilicity and percentage loading of the drug predominantly determine the rate of release. Based upon these results, IUdR and tirapazamine warrant preclinical testing for radiosensitization of human malignant brain tumors via the synthetic, implantable, biodegradable polymeric devices.

Drug use and prescribing problems in four state Medicaid programs

In this article the authors present population-level prevalence rates for 61 specific drug-related problems occurring in three State Medicaid programs (Maryland, Iowa, and Washington) from 1989 through 1996 and a fourth (Georgia) from 1994 through 1996. The findings represent the first application of a consistent drug utilization review (DUR) screener program to Medicaid data across States. The study finds major differences in DUR failure rates among the four States with the lowest rates in Georgia and the highest in Washington. Only Iowa showed any population-level reduction in DUR failure rates during the study period, however, rates for community-dwelling elderly fell in most States.

Implantable biodegradable polymers for IUdR radiosensitization of experimental human malignant glioma

PURPOSE

The potential of halogenated pyrimidines for the radiosensitization of human malignant gliomas remains unrealized. To assess the role of local delivery for radiosensitization, we tested a synthetic, implantable biodegradable polymer for the controlled release of 5-iodo-2'-deoxyuridine (IUdR) both in vitro and in vivo and the resultant radiosensitization of human malignant glioma xenografts in vivo.

MATERIALS AND METHODS

In vitro: To measure release, increasing (10%, 30%, 50%) proportions (weight/weight) of IUdR in the polyanhydride [(poly(bis(p-carboxyphenoxy)-propane) (PCPP): sebacic acid (SA) (PCPP : SA ratio 20:80)] polymer discs were incubated (1 ml phosphate-buffered saline, 37 degrees C). The supernatant fractions were serially assayed using high performance liquid chromatography. To measure modulation of release, polymer discs were co-loaded with 20 microCi 5-125-iodo-2'-deoxyuridine (125-IUdR) and increasing (10%, 30%, or 50%) proportions of D-glucose. To test radiosensitization, cells (U251 human malignant glioma) were sequentially exposed to increasing (0 or 10 microM) concentrations of IUdR and increasing (0, 2.5, 5.0, or 10 Gy) doses of acute radiation. In vivo. To measure release, PCPP : SA polymer discs having 200 microCi 125-IUdR were surgically placed in U251 xenografts (0.1-0.2 cc) growing in the flanks of nude mice. The flanks were reproducibly positioned over a collimated scintillation detector and counted. To measure radiosensitization, PCPP : SA polymer discs having 0% (empty) or 50% IUdR were placed in the tumor or contralateral flank. After five days, the tumors were acutely irradiated (500 cGy x 2 daily fractions).

RESULTS

In vitro: Intact IUdR was released from the PCPP : SA polymer discs in proportion to the percentage loading. After 4 days the cumulative percentages of loaded IUdR that were released were 43.7 +/- 0.1, 70.0 +/- 0.2, and 90.2 +/- 0.2 (p < 0.001 ANOVA) for the 10, 30, and 50% loadings. With 0, 10, 30, or 50% D-glucose co-loading, the cumulative release of 125-IUdR from PCPP : SA polymers was 21, 70, 92, or 97% (p < 0.001), respectively, measured 26 days after incubation. IUdR radiosensitized U251 cells in vitro. Cell survival (log10) was -2.02 +/- 0.02 and -3.68 +/- 0.11 (p < 0.001) after the 10 Gy treatment and no (control) or 10 microM IUdR exposures, respectively. In vivo: 125-IUdR Release: The average counts (log10 cpm +/- SEM) (hours after implant) were 5.2 +/- 0.05 (0.5), 4.3 +/- 0.07 (17), 3.9 +/- 0.08 (64), and 2.8 +/- 0.06 (284). Radiosensitization: After intratumoral implantation of empty polymer or intratumoral 50% IUdR polymer, or implantation of 50% IUdR polymers contralateral to tumors the average growth delays of tumors to 4 times the initial volumes were 15.4 +/- 1.8, 20.1 + 0.1, and 20.3 + 3.6 (mean + SEM) days, respectively (p = 0.488 one-way ANOVA). After empty polymer and radiation treatments, no tumors regressed and the growth delay was 31.1 + 2.1 (p = 0.046 vs. empty polymer alone) days. After implantation of 50% IUdR polymers either contralateral to the tumors or inside the tumors, followed by radiation, tumors regressed; growth delays to return to the initial average volumes of 14.0 + 3.6 or 24.2 + 0.2 (p < 0.01) days, respectively.

CONCLUSIONS

Synthetic, implantable biodegradable polymers hold promise for the controlled release and local delivery of IUdR for radiosensitization of gliomas.

All-trans- and 9-cis-retinoic acid inhibit growth of normal human and murine B cell precursors

In the present paper we demonstrate that physiologic levels (10 nM) of both all-trans- and 9-cis-retinoic acid (RA) are potent inhibitors of the growth of human as well as murine B cell precursors in vitro. Ten nanomolar concentrations of all-trans- and 9-cis-RA reduced the DNA synthesis ([3H]thymidine uptake) of human B cell precursors (CD19+ IgM-) stimulated with O-tetradecanoylphorbol-13-acetate and ionomycin by approximately 55% and 70%, respectively. Human B cell precursors stimulated with low m.w. B cell growth factor were also inhibited by RA. Ten nanomolar concentrations of either isoform of RA reduced DNA synthesis by approximately 50%. No effect of RA on differentiation to sIgM positive cells was noted. The potent growth-inhibiting effect of RA on human B cell precursors was confirmed in the murine cell system. B lymphopoiesis from murine hematopoietic precursors (Lin-B220(+)-containing cells) was induced by stimulation with IL-7. Concentrations of all-trans- and 9-cis-RA as low as 10 pM reduced the colony-forming ability of the IL-7-stimulated Lin-B220(+)-containing cells. Ten nanomolar concentrations of either isoform reduced colony formation by approximately 60%. RA was not toxic to the cells, as the inhibition of colony formation after 24 h was reversible at concentrations as high as 1 microM. The growth-inhibiting effect of RA was directly mediated, as revealed by single cell analysis of the Lin-B220(+)-containing cells. Thus, vitamin A appears to have an important role in regulation of B lymphopoiesis.

All-trans- and 9-cis-retinoic acid inhibit growth of normal human and murine B cell precursors

In the present paper we demonstrate that physiologic levels (10 nM) of both all-trans- and 9-cis-retinoic acid (RA) are potent inhibitors of the growth of human as well as murine B cell precursors in vitro. Ten nanomolar concentrations of all-trans- and 9-cis-RA reduced the DNA synthesis ([3H]thymidine uptake) of human B cell precursors (CD19+ IgM-) stimulated with O-tetradecanoylphorbol-13-acetate and ionomycin by approximately 55% and 70%, respectively. Human B cell precursors stimulated with low m.w. B cell growth factor were also inhibited by RA. Ten nanomolar concentrations of either isoform of RA reduced DNA synthesis by approximately 50%. No effect of RA on differentiation to sIgM positive cells was noted. The potent growth-inhibiting effect of RA on human B cell precursors was confirmed in the murine cell system. B lymphopoiesis from murine hematopoietic precursors (Lin-B220(+)-containing cells) was induced by stimulation with IL-7. Concentrations of all-trans- and 9-cis-RA as low as 10 pM reduced the colony-forming ability of the IL-7-stimulated Lin-B220(+)-containing cells. Ten nanomolar concentrations of either isoform reduced colony formation by approximately 60%. RA was not toxic to the cells, as the inhibition of colony formation after 24 h was reversible at concentrations as high as 1 microM. The growth-inhibiting effect of RA was directly mediated, as revealed by single cell analysis of the Lin-B220(+)-containing cells. Thus, vitamin A appears to have an important role in regulation of B lymphopoiesis.

Tumor necrosis factor-alpha (TNF-alpha) potently enhances in vitro macrophage production from primitive murine hematopoietic progenitor cells in combination with stem cell factor and interleukin-7: novel stimulatory role of p55 TNF receptors

Tumor necrosis factor-alpha (TNF-alpha) is a bifunctional regulator of hematopoiesis, and its cellular responses are mediated by two distinct cell surface receptors. TNF-alpha generally inhibits the growth of primitive murine hematopoietic progenitor cells (Lin-Scal+) in response to multiple cytokine combinations, and the p75 TNF receptor is essential in signaling such inhibition. In the present study we show the reverse phenomenon in that TNF-alpha on the same progenitor cell population in combination with stem cell factor (SCF) and interleukin-7 (IL-7) through the p55 TNF receptor can recruit additional progenitors to proliferate. In contrast, TGF-beta 1, another bifunctional regulator of hematopoietic progenitor cell growth, completely blocked SCF plus IL-7-induced proliferation. TNF-alpha increased the number of responding progenitors, as well as the size of the colonies formed. The synergistic effects of TNF-alpha were seen at the single cell level, suggesting that its effects are directly mediated. Finally, whereas SCF plus IL-7 promoted primarily granulopoiesis, the addition of TNF-alpha switched the differentiation toward the production of almost exclusively macrophages.

Stem cell factor and interleukin-7 synergize to enhance early myelopoiesis in vitro

Interleukin-7 (IL-7) has been shown to be a critical factor in murine lymphoid development. It stimulates pre-B cells to divide in the absence of stroma cells and it is an important growth regulator of immature and mature T cells. IL-7 has been shown to synergize with stem cell factor (SCF) to provide a potent growth stimulus for pre-B cells. However, the combined effects of IL-7 and SCF on murine primitive hematopoietic cells in vitro have not been established. In the present study, the effects of recombinant rat (rr) SCF and recombinant human (rh) IL-7 on primitive murine bone marrow progenitors (Lin-Sca1+) were investigated in single-cell cloning experiments. rhIL-7 alone had no proliferative effect on Lin-Sca1+ cells, but in a dose-dependent manner directly enhanced rrSCF-induced colony formation, with an average increase in colony numbers of 2.7-fold. Interestingly, the cells formed in response to SCF and IL-7 were predominantly mature granulocytes. Thus, SCF and IL-7 synergize to stimulate early myelopoiesis in vitro.

All-trans- and 9-cis-retinoic acid: potent direct inhibitors of primitive murine hematopoietic progenitors in vitro

Retinoic acid (RA) stimulates the clonal proliferation of mature bone marrow progenitor cells and inhibits the growth of leukemic progenitors, whereas its effects on normal primitive hematopoietic progenitors have not yet been investigated. This study investigated the ability of all-trans- and 9-cis-RA to modulate the proliferation and differentiation of murine Lin-Sca-1+ bone marrow progenitor cells. Both RA isoforms inhibited in a reversible and dose-dependent fashion, the proliferation of multi- but not single-factor responsive Lin-Sca-1+ progenitor cells. The 50% effective dose was 10 nM for both all-trans- and 9-cis-RA. Maximum inhibition was observed at 100-1,000 nM RA, resulting in a 50-75% reduction in the number of proliferative clones. Lin-Sca-1+ cells with high proliferative potential were preferentially inhibited by RA, resulting in a 80-100% inhibition depending on the hematopoietic growth factors stimulating their growth. The inhibitory effects of RA were directly mediated on the target cell, since the effects were observed at the single cell level. Furthermore, autocrine transforming growth factor beta (TGF-beta) production can probably not account for the observed inhibitory effects of RA, since a TGF-beta neutralizing antibody did not block RA-induced inhibition. Whereas RA, in general, is a differentiation-inducing agent, treatment of Lin-Sca-1+ progenitors resulted in the accumulation of an increased fraction of blasts and immature myeloid cells. Thus, RA inhibits the proliferation as well as differentiation of normal primitive hematopoietic progenitor cells.

Metabolic labeling of rod outer segment phospholipids in miniature poodles with progressive rod-cone degeneration (prcd)

The recessive genetic defect in miniature poodles which results in progressive rod-cone degeneration (prcd) has been investigated in an attempt to determine the biochemical abnormality involved. In the present study, the rod outer segments of young prcd affected miniature poodles and normal dogs have been compared with respect to the incorporation of intravitreally injected [3H]palmitic acid. [14C]linolenic acid, and [14C]docosahexaenoic acid into neutral lipids and phospholipids as well as [3H]palmitate and [14C]leucine into rhodopsin. In addition, 3 mm trephined punches of retinas were incubated with [3H]palmitic acid, [3H]arachidonic acid, [14C]linolenic acid, [3H]serine, [14C]glycerol and [14C]leucine. No difference in incorporation of labeled precursors into lipids or rhodospin was noted between prcd affected and normal retinas. Phosphatidyl choline appeared to function as a carrier of fatty acids to the rod outer segment where they were redistributed to other phospholipids. An interesting lack of conversion of the essential fatty acid linolenic acid to docosahexaenoic acid was noted in both normal and affected retinas. This conversion involves elongation and desaturation of linolenic acid and may take place primarily in extraretinal tissues such as the liver. This finding, in conjunction with a parallel study of plasma fatty acids which has shown significantly lower levels of docosahexaenoic acid in prcd affected poodles, points to a possible systemic defect in the metabolism or transport of docosahexaenoic acid, a fatty acid uniquely enriched in the photoreceptor outer segments.

Metabolic labeling of normal canine rod outer segment phospholipids in vivo and in vitro

Twenty-four hours after the intravitreal injection of [3H]palmitate and [14C]docosahexaenoate in dogs, the rod outer segment phospholipids are highly labeled. Palmitate is found predominantly in phosphatidylcholine (PC), with lesser amounts in phosphatidylethanolamine (PE) and very little in either phosphatidylserine (PS) or phosphatidylinositol (PI). Docosahexaenoate most heavily labeled PE followed by PC, with lesser amounts in PS and very little in PI. Two-hour incubations of 3 mm trephine buttons removed from dog retinas produced very similar patterns of labeling with palmitate and docosahexaenoate. In vitro incubation of retina buttons with [3H]arachidonate produced heavy labeling of PI, with much less in PC and very little in either PS or PE. [3H]Glycerol labeled in PC, PI and PE in descending order but PS almost not at all. [3H]Serine labeled PS predominantly, but small amounts were found in PC, PE and PI. The trephine retina buttons can be utilized for multiple-precursor incubations and studies of differential metabolism in retinal regions, particularly when studying scarce tissue from mutant animals or humans with inherited retinal degenerations.