A Clinical-Community Partnership to Address Food Insecurity and Reduce Emergency Department Utilization Among Medicaid-Insured Patients in North Carolina

CONTEXT

Socioeconomic risk factors have the greatest impact on overall health trajectory. Patients with Medicaid insurance are more likely to experience food insecurity, in addition to poor health and increased health care utilization. Targeted food and produce prescription programs can reduce food insecurity, but sustainable implementation is challenging and evidence demonstrating the impact on clinical utilization outcomes is lacking.

PROGRAM

In 2021, a cross-sector collaboration between Mecklenburg County Public Health, Reinvestment Partners, and Atrium Health initiated a food prescription program in urban North Carolina. A low-cost mass text message campaign was used to identify and enroll Medicaid-insured patients with a history of emergency department (ED) utilization.

METHODS

A nonrandomized before/after evaluation design was used with a 12-month data collection window (6 months before/after program enrollment) for 711 patients enrolled between June 2021 and 2022. Changes in the odds of nonadmission ED utilization were modeled using logistic regression, adjusting for race/ethnicity, gender, age, comorbidity, and dose, along with interaction by comorbidity.

RESULTS

A majority of the sample was non-Hispanic Black (61%; n = 436), female (90%; n = 643), with "none to mild" chronic disease comorbidity (81%; n = 573). The unadjusted and adjusted odds of nonadmission ED utilization significantly reduced between time periods, along with significant interaction by comorbidity. Among the subsamples, patients with "none to mild" comorbidity showed 34% reduction in odds of nonadmission ED utilization (OR = 0.64; 95% CI, 0.47-0.86).

DISCUSSION

Food prescription programming targeting Medicaid-insured patients may reduce ED utilization, particularly among those without severe comorbidity. Retrospective data collection and sample homogeneity reduced the quality of evidence, but results offer a pragmatic example that can be replicated for further study. Additional research is needed to strengthen the body of evidence and support cross-sector investment in food and produce prescription programming.

School-Based Telemedicine and Reduced Avoidable Emergency Care Among Rural Pediatric Patients

Objective: Children living in rural communities have disparate access to preventive health care, shifting the burden of care delivery to emergency services. This study examined the association of school-based telemedicine (SBT) and avoidable emergency department (ED) utilization in rural historically underserved pediatric patients served through an SBT program. Methods: A retrospective analysis was conducted using electronic medical records and claims data from a large integrated health care system serving as the majority health care provider in the area. Participants included all pediatric patients served through an SBT program between 2017 and 2020 across three rural North Carolina counties. The study was a quasi-experimental before/after design comparing 12-month time periods before and after a patient's index virtual care visit. A subset of patients served 12 months before the start of the coronavirus 2019 (COVID-19) pandemic in 2020 was extracted and analyzed separately for a sensitivity analysis. Results: The complete sample included 1,236 patients. The odds of having an avoidable ED visit were reduced by 33% between time periods, and the estimated count of visits was reduced by 26%. (Models were adjusted for race/ethnicity, gender, age, and insurance payer.) No significant differences in unavoidable ED utilization were observed. The sensitivity analysis showed similar trends. Conclusions: Results demonstrate that telemedicine can improve access to health care and may offset the burden of avoidable care through emergency health services. Policy changes and increased use during the COVID-19 pandemic have created an optimal environment for telemedicine expansion to reduce health care access disparities.

Residential Segregation and Emergency Department Utilization Among an Underserved Urban Emergency Department Sample in North Carolina

BACKGROUND Residential segregation is a spatial manifestation of structural racism. Racial disparities in emergency department (ED) utilization mirror social inequity in the larger community. We evaluated associations between residential segregation and ED utilization in a community with known disparities and geographically concentrated social and health risk.METHODS Cross-sectional data were collected from electronic medical records of 101 060 adult ED patients living in Mecklenburg County, North Carolina in 2017. Community context was measured as residential segregation using the dissimilarity index, categorized into quintiles (Q1-Q5) using 2013-2017 American Community Survey estimates, and residency in a public health priority area (PHPA). The outcome was measured as total ED visits during the study period. Associations between community context and ED utilization were modeled using Anderson's behavioral model of health service utilization, and estimated using negative binomial regression, including interaction terms by race.RESULTS Compared to areas with the lowest proportions of Black residents (Q1), living in Q4 was associated with higher rates of ED utilization among Black/Other (AME = 0.11) and White (AME = 0.23) patients, while associations with living in Q5 were approximately equivalent (AME = 0.12). PHPA residency was associated with higher rates of ED utilization among Black/Other (AME = 0.10) and White patients (AME = 0.22).LIMITATIONS Associations should not be interpreted as causal, or be generalized to the larger community without ED utilization. Health system leakage is possible but limited.CONCLUSIONS Residential segregation is associated with higher rates of ED utilization, as are PHPA residency and other individual-level determinants.

Racial/Ethnic Disparities in Health Care Setting Choice for Adults Seeking Severe Acute Respiratory Syndrome Coronavirus 2 Testing

OBJECTIVES

Equitable access to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing is important for reducing disparities. We sought to examine differences in the health care setting choice for SARS-CoV-2 testing by race/ethnicity and insurance. Options included traditional health care settings and mobile testing units (MTUs) targeting communities experiencing disproportionately high coronavirus disease 2019 (COVID-19) rates.

METHODS

We conducted a retrospective, observational study among patients in a large health system in the Southeastern US. Descriptive statistics and multinomial logistic regression analyses were employed to evaluate associations between patient characteristics and health care setting choice for SARS-CoV-2 testing, defined as: (1) outpatient (OP) care; (2) emergency department (ED); (3) urgent care (UC); and (4) MTUs. Patient characteristics included race/ethnicity, insurance, and the existence of an established relationship with the health care system.

RESULTS

Our analytic sample included 105,386 adult patients tested for SARS-CoV-2. Overall, 55% of patients sought care at OP, 24% at ED, 12% at UC, and 9% at MTU. The sample was 58% White, 24% Black, 11% Hispanic, and 8% other race/ethnicity. Black patients had a higher likelihood of getting tested through the ED compared with White patients. Hispanic patients had the highest likelihood of testing at MTUs. Patients without a primary care provider had a higher relative risk of being tested through the ED and MTUs versus OP.

CONCLUSIONS

Disparities by race/ethnicity were present in health care setting choice for SARS-CoV-2 testing. Health care systems may consider implementing mobile care delivery models to reach vulnerable populations. Our findings support the need for systemic change to increase primary care and health care access beyond short-term pandemic solutions.

Social and demographic characteristics of frequent or high-charge emergency department users: A quantile regression application

OBJECTIVE

Heavy users of the emergency department (ED) are a heterogeneous population. Few studies have captured the social and demographic complexity of patients with the largest burden of ED use. Our objective was to model associations between social and demographic patient characteristics and quantiles of the distributions of ED use, defined as frequent and high-charge.

METHODS

We conducted a cross-sectional analysis of electronic health and billing records of 99 637 adults residing in an urban North Carolina county who visited an ED within Atrium Health, a large integrated health care system, in 2017. Mid-quantile and standard quantile regression models were used for count and continuous responses, respectively. Frequent and high-charge use outcomes were defined as the median (0.50) and upper quantiles (0.75, 0.95, 0.99) of the outcome distributions for total billed ED visits and associated charges during the study period. Patient characteristic predictors were: insurance coverage (Medicaid, Medicare, private, uninsured), total visits to ambulatory care during the study period (0, 1, >1), and patient demographics: age, gender, race, ethnicity, and living in an underprivileged community called a public health priority area (PHPA).

RESULTS

Results showed heterogeneous relationships that were stronger at higher quantiles. Having Medicaid or Medicare insurance was positively associated with ED visits and ED charges at most quantiles. Racial and geographic disparities were observed. Black patients had more ED visits and lower ED charges than their White counterparts at most quantiles of the outcome distributions. Patients living in PHPAs, had lower charges than their counterparts at the median but higher charges at the 0.95 and 0.99 quantiles.

CONCLUSIONS

The relationships between patient characteristics and frequent and high-charge use of the ED vary based on the level of use. These findings can be used to inform targeted interventions, tailored policy, and population health management initiatives.

Using cloud-based, open-source technology to evaluate, improve, and rapidly disseminate community-based intervention data

Building Uplifted Families (BUF) is a cross-sector community initiative to improve health and economic disparities in Charlotte, North Carolina. A formative evaluation strategy was used to support iterative process improvement and collaborative engagement of cross-sector partners. To address challenges with electronic data collection through REDCap Cloud, we developed the BUF Rapid Dissemination (BUF-RD) model, a multistage data governance system supplemented by open-source technologies, such as: Stage 1) data collection; Stage 2) data integration and analysis; and Stage 3) dissemination. In Stage 3, results were disseminated through an interactive dashboard developed in RStudio using RShiny and Shiny Server solutions. The BUF-RD model was successfully deployed in a 6-month beta test to reduce the time lapse between data collection and dissemination from 3 months to 2 weeks. Having up-to-date preliminary results led to improved BUF implementation, enhanced stakeholder engagement, and greater responsiveness and alignment of program resources to specific participant needs.

Development, Implementation, and Results from a COVID-19 Messaging Campaign to Promote Health Care Seeking Behaviors Among Community Clinic Patients

Care-delays can further exacerbate racial and ethnic health disparities in novel coronavirus disease 2019 (COVID-19) related complications. The purpose of our study was to describe and evaluate a Patient Engagement Messaging campaign (PEM campaign) promoting health care seeking behaviors among community and rural clinic patients in North Carolina. Text and voice messages were delivered over 3-weeks. Messages encouraged patients to call a regional operation call center (ROC) line for information related to health care appointments and testing. A cross-sectional evaluation was conducted on the total population (n = 48,063) and a sample without recent health care contact (n = 29,214). Among the sample, logistic regression was used to model determinants of calls to the ROC-line and associations between calling the ROC-line and health care seeking behaviors (scheduling any health care appointment or receiving a COVID-19 test). 69.9% of text messages and 89% of voice messages were delivered. Overall, 95.4% of the total population received at least 1 message. Successful delivery was lower among Black patients and higher among patients with moderate health-risk comorbidities. Among the sample, 7.4% called the ROC-line, with higher odds of calling among minority patients (vs. White) and among Medicaid and uninsured (vs. private insurance). Calling the ROC-line was associated with higher odds of scheduling any health care appointment (OR: 4.14; 95% CI 2.93–5.80) and receiving a COVID-19 test (OR: 2.39; 95% CI 1.64–3.39). Messaging campaigns may help disconnected patients access health care resources and reduce disparities, but are likely still limited by existing barriers.

Ambulatory care, insurance, and avoidable emergency department utilization in North Carolina

OBJECTIVE

To examine whether and how avoidable emergency department (ED) utilization is associated with ambulatory or primary care (APC) utilization, insurance, and interaction effects.

DESIGN AND SAMPLE

A cross-sectional analysis of electronic health records from 70,870 adults residing in Mecklenburg County, North Carolina, who visited an ED within a large integrated healthcare system in 2017.

METHODS

APC utilization was measured as total visits, categorized as: 0, 1, and > 1. Insurance was defined as the method of payment for the ED visit as: Medicaid, Medicare, private, or uninsured. Avoidable ED utilization was quantified as a score (aED), calculated as the sum of New York University Algorithm probabilities multiplied by 100. Quantile regression models were used to predict the 25th, 50th, 75th, 95th, and 99th percentiles of avoidable ED scores with APC visits and insurance as predictors (Model 1) and with an interaction term (Model 2).

RESULTS

Having >1 APC visit was negatively associated with aED at the lower percentiles and positively associated at higher percentiles. A higher aED was associated with having Medicaid insurance and a lower aED was associated with having private insurance, compared to being uninsured. In stratified models, having >1 APC visit was negatively associated with aED at the 25th percentile for the uninsured and privately insured, but positively associated with aED at higher percentiles among the uninsured, Medicaid-insured, and privately insured.

CONCLUSIONS

The association between APC utilization and avoidable ED utilization varied based on segments of the distribution of ED score and differed significantly by insurance type.

Effectiveness of a Playground Intervention for Antisocial, Prosocial, and Physical Activity Behaviors

BACKGROUND

We examined the effectiveness of Peaceful Playgrounds™ (P2) to decrease antisocial behaviors (ASB) while increasing physical activity (PA) and prosocial behaviors (PSB) in elementary school children.

METHODS

A longitudinal, cluster-randomized design was employed in 4 elementary school playgrounds where students (third to fifth) from 2 intervention and 2 control schools were observed during recess periods. The intervention included environmental changes (eg, marked surfaces) and student education. Data were collected using systematic observations of youth behavior and semistructured interviews conducted with key informants. Mixed-effects regression models controlling for scans nested within days nested within schools estimated the interaction of measurement period and treatment condition on children's PA, PSB, and ASB. It was hypothesized that children in intervention, but not control schools, would demonstrate increased PA/PSB and decreased ASB.

RESULTS

Contrary to the hypotheses, intervention and control schools showed favorable changes for all dependent variables except for PSB, but 1 intervention and 1 control school drove these effects. Follow-up interviews indicated variability in implementation and lack of adherence to the control condition.

CONCLUSIONS

P2 may promote increased PA during recess, but these results demonstrate the complexity of intervention implementation and the need for rigor when measuring intervention fidelity in real-world settings.

Addressing obesity with pediatric patients and their families in a primary care office

Pediatric obesity is a prevalent condition that has devastating health consequences for children. If left untreated, it can result in adult obesity and related chronic health conditions. Special considerations need to be made for treatment in the pediatric population including an adjustment of treatment goals (weight maintenance vs weight loss) and treatment methodologies. Special emphasis needs to be made to support a child's development of healthy behavior choices. The use of medications should be avoided when possible because long-term health effects of pharmacotherapy treatment in children are unknown.

Bicycling policy indirectly associated with overweight/obesity

BACKGROUND

Policies to enhance bicycling are correlated with health outcomes. Research has yet to provide an adequate, empirically derived explanation for this finding.

PURPOSE

To examine a comprehensive model of a pathway potentially linking bicycle policies to overweight/obesity.

METHODS

Data representing multiple years between 2006 and 2012 from CDC, U.S. Census Bureau, U.S. Department of Transportation, and the Alliance for Biking and Walking were subjected to bivariate and multivariate analyses in 2013. A path model was created to explain the relationship between bicycle policies and overweight/obesity in the 48 largest U.S. cities.

RESULTS

Zero-order correlations were significant between the number of bicycle policies and the percentage of workers bicycling to work and rates of overweight/obesity. These relationships did not remain statistically significant in the multivariate analysis. However, more bicycle policies were associated with a greater number of bicycle infrastructure components (p<0.005). In turn, bicycling infrastructure components were positively related to the percentage of workers bicycling to work (p<0.001), which was inversely associated with overweight/obesity rates (p<0.05).

CONCLUSIONS

The results of this study suggest that large cities with more policies aimed at promoting bicycling have fewer overweight/obese residents, partially because the policies are related to supportive bicycling infrastructures that promote bicycling to work.

Relations between perceptions of environmental features and physical activity

Studies have examined associations between environmental features and physical activity, but there has been no exploration of adult perceptions about the influence environmental features have on physical activity. This study assessed associations between perceptions of environmental features and physical activity. 305 women and 229 men (18-91 years of age) were interviewed in their homes. Questions elicited self-report data on physical activities they performed in their neighborhood (sidewalks near home) and perceptions about neighborhood environmental features. Women (86.4%) were more likely than men (79.3%) to be active in their neighborhoods and view the features as influential. The influences features were perceived to have on physical activity were associated with activity performed in the neighborhood, but perceptions of the conditions of features were not. Interviewers of adults about relationships between environmental features and physical activity should consider perceptions about the influence the feature exerts on activity levels.

Outcomes from an urban pediatric obesity program targeting minority youth: the Healthy Hawks program

BACKGROUND

The aim of this study was to describe the outcomes of a family-based behavioral group treatment program with a group of urban, minority, low-income families.

METHODS

Two hundred and ten families enrolled in a 12-week family-based behavioral group treatment program for pediatric obesity. The program was offered in English and in Spanish and targeted the enrollment of low-income highly diverse youth and families. Primary outcome measures included child BMI z-score (zBMI), maternal BMI, 3-day diet record, and accelerometer.

RESULTS

Seventy-one percent of enrolled families completed the 12-week program. Significant 12-week outcomes were achieved for child zBMI (p<0.001) and for maternal BMI (p<0.001), as well as for child kcals (p<0.001), sugar-sweetened beverages (p=0.017), and red foods (p<0.001). Only change in child zBMI remained significant at 1 year (p<0.05). Physical activity outcomes were not significant and not in the expected direction. There were no differences in outcome by race/ethnicity, but by age, younger children had higher zBMI at baseline and were also more likely to decrease zBMI during the intervention.

CONCLUSIONS

It is possible to enroll and maintain urban, minority, low-income families in a family-based behavioral group treatment program for pediatric obesity. Outcome data indicate that these families achieve significant outcomes on zBMI, and that children who remain available for assessment maintain this at 1 year, which is an improvement over previous research using other intervention methodologies with this population.

Psoralen-modified clamp-forming antisense oligonucleotides reduce cellular c-Myc protein expression and B16-F0 proliferation

The c-myc protooncogene plays an important role in the abnormal growth pattern of melanoma cells. In an attempt to inhibit c-Myc expression and the growth of an established murine melanoma cell line, we targeted homopurine sequences within the mouse myc mRNA with modified antisense oligonucleotides (AS ODNs). Psoralen was conjugated to the 5'-end of these clamp-forming oligonucleotides (clamp ODNs). Gel mobility shift analysis demonstrated a sequence-specific interaction between the active clamp ODNs (Myc-E2C and Myc-E3C) and the 1.4 kb c-myc mRNA, but no interaction with the control clamp ODN (SCR**). This association was further confirmed by thermal denaturation studies. In vitro translation assays demonstrated that both Myc-E2C and Myc-E3C at 5 microM inhibited c-Myc expression >99% after UV activation at 366 nm. Immunostaining of B16-F0 cells with a c-Myc monoclonal antibody revealed a significant reduction in c-Myc after clamp ODN treatment compared with the untreated or SCR** control-treated cells. This result was corroborated by western blot analysis. Utilizing the MTT assay to determine the effects of ODN-mediated c-Myc reduction on B16-F0 growth, we observed 60 and 64% reductions in growth after treatment with 5 microM Myc-E3C and Myc-E2C, respectively. We attribute the enhanced effectiveness of the clamp ODNs to psoralen activation. Our preliminary data suggest that inhibiting c-Myc overexpression results in a significant reduction in abnormal proliferation of B16-F0 melanoma cells and that the increased efficiency of clamp ODNs may provide an important advantage for their use in antisense therapies.

The integral divalent cation within the intermolecular purine*purine. pyrimidine structure: a variable determinant of the potential for and characteristics of the triple helical association

In vitro assembly of an intermolecular purine*purine.pyrimidine triple helix requires the presence of a divalent cation. The relationships between cation coordination and triplex assembly were investigated, and we have obtained new evidence for at least three functionally distinct potential modes of divalent cation coordination. (i) The positive influence of the divalent cation on the affinity of the third strand for its specific target correlates with affinity of the cation for coordination to phosphate. (ii) Once assembled, the integrity of the triple helical structure remains dependent upon its divalent cation component. A mode of heterocyclic coordination/chelation is favorable to triplex formation by decreasing the relative tendency for efflux of integral cations from within the triple helical structure. (iii) There is also a detrimental mode of base coordination through which a divalent cation may actively antagonize triplex assembly, even in the presence of other supportive divalent cations. These results demonstrate the considerable impact of the cationic component, and suggest ways in which the triple helical association might be positively or negatively modulated.

Efficient delivery of triplex forming oligonucleotides to tumor cells by adenovirus-polylysine complexes

Oligonucleotides (ODNs) show great promise in their ability to specifically inhibit single gene expression but must cross the cell membrane, escape the endosomal vesicle, and possibly traverse the nuclear membrane to arrive at their intracellular target molecules. In an attempt to improve the delivery of phosphodiester triplex forming ODNs to malignant cells, we have constructed adenovirus-polylysine (AdpL)-ODN complexes designed to take advantage of the receptor mediated endocytosis of adenoviruses to transfer the ODNs to the cell nucleus. Treatment of several different types of tumor cells in culture by AdpL-ODN complex resulted in superior uptake and persistence of the ODNs compared to both free ODN and cationic lipid-ODN complexes. Nuclear uptake peaks at 4 h and intact ODN persists in the nucleus with a half-life of 12 h. ODN concentrations of 20-70 microM are achieved at 24 h in all monolayer cell lines evaluated to date. ODNs are detected in 50-100% of the total cell population by immunohistochemistry with apparent uptake into vesicles and nuclear localization. Luciferase expression of a co-delivered reporter plasmid suggests that these ODNs are free in the nucleus. AdpL-ODN complexes will provide a valuable tool for delivering unmodified ODNs to the nucleus of malignant cells.

Influence of GC and AT specific DNA minor groove binding drugs on intermolecular triplex formation in the human c-Ki-ras promoter

We have used DNase I footprinting and gel shift assays to characterize the interaction of DNA binding drugs mithramycin, distamycin, and berenil with an intermolecular triplex formed by the human c-Ki-ras promoter. A purine-rich triplex-forming oligonucleotide (ODN) forms a stable intermolecular triple helix (triplex) with a homopurine (PR):homopyrimidine (PY) motif in the human c-Ki-ras promoter which contains a 22bp PR:PY region (-328 to -307). This triplex structure is comprised of 15 G.G:C triplets interspersed with 7 T.A:T triplets. Mithramycin binding sites in the human c-Ki-ras promoter encompass most of the triplex target site and three G-C-rich sequences downstream of this triplex-forming region. Mithramycin binding within the c-Ki-ras promoter completely abrogates triplex formation. Furthermore, the addition of mithramycin to pre-formed triplex by c-Ki-ras promoter displaces the major groove bound ODN. Five prominent distamycin binding sites are noted within the c-Ki-ras promoter including the triplex-forming site as well as A-T-rich regions upstream and downstream of the triplex site. Berenil does not bind within the triplex target sequence, and only one berenil binding sequence downstream of the triplex motif was present within the c-Ki-ras promoter fragment. Neither distamycin nor berenil prevents triplex formation, and, furthermore, the addition of either distamycin or berenil to the pre-formed triplex structure did not displace the major-groove-bound third strand. This study demonstrates that GC-specific and AT-specific minor groove ligands differentially affect the intermolecular pur.pur:pyr triplex. A possible biological significance of mithramycin interaction with intramolecular triplex is discussed.

The G-C specific DNA binding drug, mithramycin, selectively inhibits transcription of the C-MYC and C-HA-RAS genes in regenerating liver

Expression of the c-myc and c-Ha-ras protooncogenes is dramatically increased in regenerating rat liver as an early response to partial hepatectomy. Nuclear runon transcription studies confirm that the increased c-myc and c-Ha-ras mRNA levels in regenerating livers reflect transcriptional activation of these genes. Mithramycin, a G-C specific DNA binding drug, prevents the increased transcriptional activity of c-myc and c-Ha-ras genes after hepatectomy but does not alter the transcriptional activity of the beta-actin gene. Continuous exposure of rats to mithramycin after hepatectomy prevents the increase in both c-myc and c-Ha-ras expression and blocks the increased cellular proliferation characteristic of regeneration. The delayed increase in c-myc and c-Ha-ras gene expression is associated with a delay in cellular proliferation. The inhibition of c-myc and c-Ha-ras transcription by mithramycin, the delay in cellular proliferation, and the ability of mithramycin to prevent protein binding to the c-myc promoter, suggest that the increased expression of these genes is a necessary component of liver regeneration.

Triplex formation inhibits HER-2/neu transcription in vitro

Triplex-forming oligonucleotides (TFOs) have been shown to bind to target DNA sequences in several human gene promoters such as the c-myc oncogene, the epidermal growth factor receptor, and the dihydrofolate reductase genes. TFOs have been shown to inhibit transcription in vitro and gene expression in cell culture of the c-myc and other genes. The HER-2/neu oncogene, which is overexpressed in breast cancer and other human malignancies, contains a purine-rich sequence in its promoter, which is favorable for purine:purine:pyrimidine (R:R:Y) triplex formation. Although its function in the HER-2/neu promoter is unknown, this purine-rich site is homologous to a protein-binding sequence in the promoter of the epidermal growth factor receptor that is necessary for efficient transcription of this gene. We have shown that this sequence is a site for nuclear protein binding by incubation with a crude nuclear extract. We describe the formation of an interstrand triplex using a purine-rich oligonucleotide antiparallel to this purine-rich target sequence of the HER-2/neu promoter. Triplex formation by the oligonucleotide prevents protein binding to the target site in the HER-2/neu promoter in vitro. We have shown that this oligonucleotide is a potent and specific inhibitor of HER-2/neu transcription in an in vitro assay. The triplex target site contains a single pyrimidine base that does not conform to the R:R:Y triplex motif. In an attempt to abrogate the potentially destabilizing effects of this pyrimidine base on triplex formation, we have substituted an abasic linker for the pyrimidine residue in the triplex forming oligonucleotide. Triplex formation with the modified oligonucleotide appears to occur with approximately equivalent binding affinity. Triplex formation in the HER-2/neu oncogene promoter prevents transcription in vitro and may represent a future modality for specific inhibition of this gene in vivo.

Enzyme selectivity analyses of arylsulfonylamino acid aldose reductase inhibitors

Arylsulfonylamino acids, displaying a wide range of inhibitory activities versus rat lens aldose reductase (RLAR), were analyzed for enzyme selectivity in several test systems. These RLAR inhibitors were found not to produce significant inhibition of genetically-linked reductases (aldehyde reductase, ALR), catalytically similar reductases (Pachysolen tannophilus xylose reductase, PTXR), functionally distinct oxidoreductases (glutathione reductase, GR, lactate dehydrogenase, LDH, and gamma-transaminase, GABA-T), and thymidylate synthase (TS). These data suggest that aldose reductase differs significantly from other oxidoreductases in its inhibitor binding domain(s). Furthermore, the aldose reductase selectivity demonstrated by the arylsulfonylamino acids suggests that these compounds may not inhibit other key metabolic transformations in various cell types and that they may function as selective probes for studies of the relationship between aldose reductase mediated biochemical changes and the pathologies of chronic diabetes.

Relative structure-inhibition analyses of the N-benzoyl and N-(phenylsulfonyl) amino acid aldose reductase inhibitors

A number of N-benzoyl amino acids were synthesized and tested to compare structure-inhibition relationships with the isosteric N-(phenylsulfonyl) amino acid (PS-amino acid) aldose reductase inhibitors. Inhibition analyses with these series reveals that their kinetic mechanisms of inhibition are similar, but that significant differences in structure-inhibition relationships exist. For example, while the PS-alanines and PS-2-phenylglycines produce enantioselective inhibition (S greater than R), no consistent pattern of enantioselectivity is observed with the isosteric N-benzoylalanines and 2-phenylglycines. Also, N-methyl and N-phenyl substitution in the PS-amino acid series does not substantially alter inhibitory activity, while similar substitutions in the N-benzoyl series (particularly N-phenyl) results in a significant increase in inhibitory activity. Proton NMR analysis of the N-benzoylsarcosines reveals that these compounds exist as a mixture of rotamers in solutions including the enzyme assay buffer and that the preferred conformer is one in which the carboxymethyl moiety is trans to the aromatic ring. Similar analyses with the N-benzoyl-N-phenylglycines demonstrate that these derivatives exist exclusively in the trans rotameric conformation in solution. No such N-substituent effects on conformation were observed in the PS-amino acid series. These results suggest that the differences in structure-inhibition trends between these structurally related series may result from the effect of substituents on preferred conformation.

Inhibitory activity and mechanism of inhibition of the N-[[(4-benzoylamino)phenyl]sulfonyl]amino acid aldose reductase inhibitors

A series of substituted N-[[(4-benzoylamino)phenyl]sulfonyl]amino acids (BAPS-amino acids) were synthesized by established methods, and the stereochemistry of the products was confirmed by HPLC analysis after chiral derivatization. When tested against aldose reductase (alditol:NADP+ oxidoreductase; EC 1.1.1.21; ALR2) isolated from rat lens, all of the BAPS-amino acids were determined to be significantly more inhibitory than the corresponding N-(phenylsulfonyl)amino acids. Structure-inhibition and enzyme kinetic analyses suggest that the BAPS-amino acids inhibit ALR2 by a mechanism similar to the N-(phenylsulfonyl)amino acids. However, multiple inhibition analyses indicate that the increased inhibitory activity of the BAPS-amino acids is a result of interaction with multiple sites present on ALR2. Enzyme specificity studies with several of the BAPS-amino acids demonstrated that these compounds do not produce significant inhibition of other nucleotide-requiring enzymes including aldehyde reductase (alcohol: NADP+ oxidoreductase; EC 1.1.1.2; ALR1).

Diastereoisomeric derivatization and liquid chromatographic analysis of N-(phenylsulfonyl)-2-phenylglycine aldose reductase inhibitors

A series of (S)- and (R)-N-(phenylsulfonyl)-2-phenylglycines are synthesized as potential inhibitors of the enzyme aldose reductase. In vitro analysis of these compounds reveals that the S-enantiomers are more potent than the corresponding R-enantiomers and that the difference in potencies between enantiomeric pairs is dependent on the nature of the ring substituent. To ensure that the enantioselectivity observed does not reflect varying degrees of racemization during the synthesis of the N-(phenylsulfonyl)-2-phenylglycines, the enantiomeric purity of these products is determined by HPLC after chiral derivatization. Each 2-phenylglycine inhibitor is derivatized with R-alpha-methylbenzylamine, and the resulting diastereomers are analyzed using reversed and normal achiral stationary phases. Reversed-phase methods with C18 or phenyl stationary phases and solvent mixtures of acetonitrile or methanol in water do not provide satisfactory resolution of the diastereomers. However, normal-phase analyses with a silica stationary phase and mixtures of methanol, ethanol, or acetonitrile in chloroform provide good separations with relatively short analysis times. The normal-phase analyses demonstrate that a single diastereomeric amide forms from each N-(phenylsulfonyl)-2-phenylglycine product, establishing that these compounds do not racemize during synthesis.

Liquid chromatographic measurement of hydrophobicity constants for N-arylsulfonylglycine aldose reductase inhibitors

The hydrophobicity constants for a series of aldose reductase inhibitors (ARIs) are determined by reversed-phase liquid chromatography. A series of reference compounds consisting of 23 barbituric acid derivatives are separated on two phenylsilica stationary phases over a range of methanol concentrations (30-80%) in 0.05 M phosphate buffer. Linear regression analysis of the measured log k' data is used to estimate the capacity factor in 100% water (log k'w) for each compound. The log k'w values are regressed against the shake-flask-measured 1-octanol-water partition coefficients, producing a correlation of 0.953. The same procedure is then used to estimate the log k'w values for a large group of ARIs and their log P values, calculated from the established relationship between log k'w and log P from the reference compounds. An initial analysis of the aldose reductase inhibitory activity of these compounds as a function of hydrophobicity alone fails to reveal a clear relationship, demonstrating the need for a multivariant approach for quantitative structure-activity analysis in this series of compounds.

Synthesis and in vitro aldose reductase inhibitory activity of compounds containing an N-acylglycine moiety

A number of N-benzoylglycines (6), N-acetyl-N-phenylglycines (7), N-benzoyl-N-phenylglycines (8), and tricyclic N-acetic acids (9-12) were synthesized as analogues of the N-acylglycine-containing aldose reductase inhibitors alrestatin and 2-oxoquinoline-1-acetic acid. Derivatives of 6, which represent ring-simplified analogues of alrestatin, are very weak inhibitors of aldose reductase obtained from rat lens, producing 50% inhibition only at concentrations exceeding 100 microM. Compounds of series 7 were designed as ring-opened analogues of the 2-oxoquinolines. While these derivatives are more potent than compounds of series 6 (IC50S of 6-80 microM), they are less active than the corresponding 2-oxoquinolines. Analogues of series 8 were designed as hybrid structures of both alrestatin and the 2-oxoquinoline-1-acetic acids. These compounds are substantially more potent than compounds of series 6 and 7 and display inhibitory activities comparable to or greater than alrestatin or the 2-oxoquinolines (IC50S of 0.1-10 microM). Of the rigid analogues of 8, the most potent derivative is benzoxindole (12) with an IC50 of 0.67 microM, suggesting that fusion of the two aromatic rings of 8 in a coplanar conformation may optimize affinity for aldose reductase in this series.

Studies of the inhibition of aldose reductase: evidence for multiple site binding

1. Comparison of structure-inhibition relationships and kinetic data between the N-[(4-benzoylamino)phenyl]sulfonyl]amino acids (BAPS-amino acids) and phenylsulfonylamino acids (PS-amino acids) suggests that the additional benzoyl moiety present in the BAPS-amino acids enhances inhibition by direct interaction with aldose reductase (EC 1.1.1.21) without altering the mode of interaction with the enzyme. 2. Also the 2-, 3- and 4-nitro regioisomers of BAPS-glycine (NBAPSG) display parallel structure- inhibition relationships with the 2-, 3- and 4-nitrobenzaldehyde substrates and the 2-, 3- and 4-nitroacetophenone competitive inhibitors. 3. Competition studies and multiple inhibition analyses demonstrate that the 4-nitrobenzoyl group of 4-NBAPSG binds at the substrate site of aldose reductase, while the PS-glycine moiety of 4-NBAPSG binds cooperatively at a distinct site.

N- and 2-substituted N-(phenylsulfonyl)glycines as inhibitors of rat lens aldose reductase

A variety of N-(phenylsulfonyl)-N-phenylglycines 5, N-(phenylsulfonyl)-2-phenylglycines 6, and N-(phenylsulfonyl)anthranilic acids 7 were prepared as analogues of the N-(phenylsulfonyl)glycine 1 aldose reductase inhibitors. In the rat lens assay, several derivatives of 5 display greater inhibitory activity than the corresponding glycines 1, suggesting that N-phenyl substitution enhances affinity for aldose reductase. Enzyme kinetic evaluations of the 4-benzoylamino analogues of 5 and 1 demonstrate that these compounds produce inhibition by the same mechanism. However, the significant differences in relative inhibitory potencies between compounds of series 5 and 1 may indicate that these compounds do not interact with the inhibitor binding site in precisely the same manner. Evaluation of the individual enantiomers of series 6 reveals that the S isomers are substantially more active than the corresponding R isomers. Also, with the exception of the naphthalene analogue 6n, the S stereoisomers of this series display greater inhibitory potencies than the glycines 1. The anthranilates 7 generally are less active than the glycines 1, demonstrating that direct incorporation of an aromatic ring in the glycine side chain may result in a decrease in affinity for aldose reductase.

Novel inhibitors of rat lens aldose reductase: N-[[(substituted amino)phenyl]sulfonyl]glycines

A number of N-[[(substituted amino)phenyl]sulfonyl]glycines 3a-n were synthesized as analogues of the simple (phenylsulfonyl)glycines 1a-c with increased lipophilic character and therefore greater aldose reductase inhibitory potential. The 2-benzoylamino derivative 3c was found to be less potent than the corresponding amine 1c as an inhibitor of rat lens aldose reductase, but both the 3- and 4-benzoylamino analogues, 3b and 3a, are substantially more potent than their amines 1b and 1a; compound 3a is the most effective inhibitor of this series, with an IC50 of 0.41 microM. The 4-benzoylamino derivative 3a is also significantly more active than the 4-acetylamino analogue 3d and the 4-benzylamino (3e) and 4-dimethylamino (3f) derivatives, suggesting that both the additional carbonyl moiety and aromatic ring present in this compound may bind to complementary sites present on the enzyme. Furthermore, structure-activity studies reveal that increasing the number of atoms between the carbonyl and aromatic moieties of 3a results in a decrease in inhibitory activity. Kinetic studies demonstrate that 3a, like other known inhibitors of aldose reductase, functions as an uncompetitive inhibitor with respect to the substrate and therefore may interact at the proposed common inhibitor binding site of this enzyme.

In vitro aldose reductase inhibitory activity of substituted N-benzenesulfonylglycine derivatives

A number of N-benzenesulfonylglycines, alanines, sarcosine, and prolines, which contain the minimum pharmacophore moieties necessary for aldose reductase inhibitory activity, were prepared and tested in the rat lens assay. In this assay, the benzenesulfonylglycines are considerably more potent than the corresponding alanine and sarcosine derivatives which, in turn, are more active than the proline analogues. Of the monosubstituted benzenesulfonylglycines, the 2-nitro and 4-amino derivatives were most active with 50% inhibitory concentration (IC50) values of 13 and 16 microM, respectively. The most potent derivatives evaluated were the beta- and alpha-naphthylenesulfonylglycines with IC50 values of 0.4 and 1.3 microM, respectively. The structure-activity data obtained from evaluation of the benzenesulfonylamino acids suggests that the aromatic ring and ring substituents, as well as the sulfonamide group and carboxylate moiety, all contribute to the inhibitory potency through direct interaction with complimentary binding sites present on aldose reductase.