Opioid Overdose Hospitalizations During COVID-19: The Experience of Pennsylvania

Objective

The COVID-19 pandemic placed extreme burden on hospitals, while opioid overdose is another challenging public health issue. This study aimed to examine the trends and outcomes of opioid overdose hospitalizations in Pennsylvania during 2018 to 2021.

Design

We identified opioid overdose hospitalizations in the state of Pennsylvania using the state-wide hospital discharge database (PHC4) 2018 to 2021. We examined the number of opioid overdose hospitalizations, the corresponding mortality and discharges against medical advice comparing the pre-COVID period (2018-2019) and the COVID period (2020-2021). We also assessed what patient and hospital characteristics were associated with in-hospital death or leaving against medical advice.

Results

A total of 13 446 opioid-related hospitalizations were identified in 2018 to 2021. Compared to pre-pandemic, a higher percentage of cases involving synthetics (17.0%vs 10.3%, P < .0001) were observed during COVID. After controlling for covariates, there was no significant difference in opioid overdose in-hospital deaths in the years 2020 to 2021 compared to 2018 to 2019 (OR = 0.846, 95% CI: 0.71-1.01, P = .065). The COVID period was significantly associated with more leaving against medical advice compared to years 2018 to 2019 (OR = 1.265, 95% CI: 1.11-1.44, P = .0003). Compared to commercial insurance, Medicaid insurance was associated with higher odds of both in-hospital death (OR = 1.383, 95% CI: 1.06-1.81, P = .0176) and leaving against medical advice (OR = 1.903, 95% CI: 1.56-2.33, P < .0001).

Conclusion

There were no substantial changes in the number of overall opioid overdose cases and deaths at hospitals following the outbreak of COVID-19 in Pennsylvania. This observation suggests that an increased number of patients may have succumbed to overdoses outside of hospital settings, possibly due to a higher severity of overdoses. Further, we found that patients were more likely to leave against medical advice during the COVID-19 pandemic.

Evaluation of Discharge Opioid Prescribing in Coronary Artery Bypass Patients Following an Opioid Stewardship Intervention for Providers

Introduction: Opioid stewardship efforts can promote safe and effective use of opioids to optimize pain control and minimize unintended consequences. The purpose of this study is to assess the difference in post-operative opioid discharge prescribing in patients undergoing coronary artery bypass graft (CABG) surgery following implementation of a tripartite opioid stewardship intervention. Methods: This was a single-center, quality improvement study at a large, quaternary academic medical center. Adult patients undergoing CABG from July 2019 to June 2020 (pre-intervention) and November 2020 to February 2021 (post-intervention) were included. The intervention included adopting hospital-wide post-surgical opioid discharge prescribing guidelines, discharge prescriber education, and electronic medical record changes. The primary outcome was the proportion of patients receiving an opioid prescription at discharge. Secondary outcomes included total morphine milligram equivalents (MME) prescribed and non-opioid analgesics prescribed at discharge. Results: A total of 200 patients were included in the study; 100 pre- and 100 post-intervention. There was no difference in opioid discharge prescribing at discharge (74% pre-intervention vs. 72% post-intervention; P = .87). There was no difference in MMEs prescribed at discharge (145.6 ± 57 pre- vs. 162.2 ± 95 post-; P = .202). No difference was seen in non-opioid analgesic prescriptions prescribed at discharge (35% pre- vs. 40% post-; P = .56). Conclusion: A multipronged opioid stewardship intervention did not lead to a reduction in opioid prescribing at discharge. Post-intervention, there was a non-statistically significant increase in the proportion of patients who received non-opioid analgesics discharge. Future studies should assess the effect of different stewardship interventions on prescribing and patient outcomes.

Factors associated with the use of the prescription monitoring program by prescribers and pharmacists in Texas

PURPOSE

To describe Texas Prescription Monitoring Program (PMP) use and identify predictors of PMP query for opioid and benzodiazepine prescriptions by prescribers and pharmacists.

METHODS

Dispensation and query records from the Texas PMP for opioid and benzodiazepine medications dispensed between October 1, 2016 and December 31, 2018 were linked using common patient identifiers. Autoregressive linear regression was used to assess trends in utilization. Hierarchical logistic models were specified to identify factors associated with provider and pharmacist query of opioid and benzodiazepine prescriptions.

RESULTS

Despite a significant increase in the total number of pharmacists (β = 169.85, p < 0.0001) and prescribers (β = 301.59, p < 0.0001) who used the PMP every month, the ratio of active to registered pharmacists (β = -0.0001, p = 0.75) and prescribers (β = -0.0015, p = 0.10) did not change. Pharmacists and prescribers were significantly more likely to query opioid and benzodiazepine prescriptions of 14 days or more, and those issued to patients new to their practice. Pharmacists were most likely to query opioid prescriptions for oxycodone (aOR = 4.51, 95%CI = 4.42-4.60) and prescribers were most likely to query prescriptions for buprenorphine (aOR = 2.24, 95%CI = 2.15-2.35) compared to codeine.

CONCLUSION

Changes in PMP utilization between October 2016 and December 2018 were driven by increasing registration, not increasing frequency of use among registered users. Use of the PMP is inconsistent and dependent upon patient characteristics thus limiting the utility of the PMP as a decision support tool. These results support the need for policy mandating PMP use in Texas and provide a useful baseline and framework to evaluate the effectiveness of mandate implementation.

Prescribers' perceptions on the impact of hydrocodone rescheduling on geriatric pain management: A qualitative study

OBJECTIVE

To qualitatively assess prescribers) perceptions regarding the consequences associated with hydrocodone rescheduling among geriatric patients being discharged from inpatient settings.

DESIGN

This was a cross-sectional study.

SETTING

Two focus groups were conducted by a trained facilitator in a metropolitan academic medical center in January 2016.

PARTICIPANTS

Prescribers who manage noncancer pain for geriatric patients were recruited. Focus groups were recorded, transcribed, and then analyzed using ATLAS.ti Qualitative Data Analysis software. Codes were derived from six primary research questions and results were summarized into key themes regarding the impact of rescheduling.

MAIN OUTCOME MEASURES

Prescribers) perceptions regarding hydrocodone rescheduling.

RESULTS

Prescribers mentioned that they review the prescription monitoring program (PMP) more often before prescribing opioids after rescheduling. They expressed concern regarding the required special serialized prescription forms needed to issue schedule II prescriptions. This led to substituting hydrocodone with potentially less effective pain medications, the inability to issue refills on hydrocodone prescriptions, and an ethical concern over prescribing hydrocodone to patients not under their direct care. Additionally, rescheduling has affected the coordination of care upon discharge, as patients moving to long-term care or skilled nursing facilities may not have adequate pain management when transferred.

CONCLUSIONS

The majority of physicians felt rescheduling negatively impacted both practical and ethical aspects of patient care related to pain management after discharge. Rescheduling has changed physicians) hydrocodone prescribing patterns, leading to more caution when prescribing hydrocodone and greater use of the PMP. Future studies should assess geriatric patients) satisfaction and quality of life regarding pain management since hydrocodone was rescheduled.

Direct medical expenditures associated with Alzheimer's and related dementias (ADRD) in a nationally representative sample of older adults - an excess cost approach

OBJECTIVE

To estimate the excess direct annual healthcare expenditures associated with Alzheimer's and related dementias(ADRD) among community-dwelling older adults in the United States.

METHODS

This retrospective cross-sectional study compared the annual healthcare expenditures between elderly individuals aged 65 years and older with ADRD (n = 662) and without ADRD (n = 13,398) using data from the Medical Expenditure Panel Survey (MEPS) for the years 2007, 2009, 2011 and 2013. Adjusted total annual medical expenditures was estimated using generalized linear model with gamma distribution and log link in 2013 U.S. dollars. Adjusted inpatient, outpatient, emergency, home healthcare and prescription drug expenditures, were estimated using two-part logit-generalized linear regression models.

RESULTS

The adjusted mean total healthcare expenditures were higher for the ADRD group as compared to the no ADRD group($14,508 vs. $10,096). Among those with ADRD, 34.3% of the expenditures were for home healthcare as compared to 4.4% among those without ADRD. Among users, the ADRD group had significantly higher home healthcare ($3,240 vs. $566) and prescription drug expenditures($3,471 vs. $2,471). There were no statistically significant differences in inpatient, emergency room and outpatient expenditures between the ADRD and no ADRD group.

CONCLUSION

ADRD in U.S. community-dwelling elders is associated with significant financial burden, primarily driven by increased home healthcare use.

A Standardized Donor Designation Ratio to Assess the Performance of Driver's License Agencies

Evaluating Department of Motor Vehicles (DMV) locations based on the percent of patrons who register as donors does not account for individual characteristics that may influence willingness to donate. We reviewed the driver's licenses of 2997 randomly selected patients at an urban medical system to obtain donor designation, age, gender, and DMV location and linked patient addresses with census tract data on race, ethnicity, income, and education. We then developed a Standardized Donor Designation Ratio (SDDR) (ie, the observed number of donors at each DMV divided by the expected number of donors based on patient demographic characteristics). Overall, 1355 (45%) patients were designated as donors. Donor designation was independently associated with younger age, female gender, nonblack race, and higher income. Across 18 DMVs, the proportion of patients who were donors ranged from 30% to 68% and SDDRs ranged from 0.82 to 1.17. Among the 6 facilities in the lowest tertile by SDDR, 3 were in the lowest tertile by percent donation. In conclusion, there is a great deal of variation across DMVs in rates of organ donor designation. SDDRs that adjust for DMV patron characteristics are distinct measures that may more accurately describe the performance of DMVs in promoting organ donation.

Cardiovascular mortality and oral antidiabetic drugs: protocol for a systematic review and network meta-analysis

INTRODUCTION

Cardiovascular diseases are the leading cause of morbidity and mortality among individuals with diabetes. Despite the beneficial effects of antidiabetic drugs (ADDs) in terms of lowering haemoglobin A1c, several ADDs have been shown to increase the risk of cardiovascular events. Given the high prevalence of cardiovascular disease among individuals with diabetes, it is important to weigh the benefits of ADDs against their cardiovascular safety. Therefore, the objective of the current study is to conduct a systematic review with network meta-analysis to compare the effects of different oral pharmacological classes of ADDs on cardiovascular safety.

METHODS AND ANALYSIS

Randomised clinical trials (RCTs) and observational studies published in English up to 31 January 2017, and which include direct and/or indirect evidence, will be included. Studies will be retrieved by searching four electronic databases and cross-referencing. Dual selection and abstraction of data will occur. The primary outcome will be cardiovascular mortality. Secondary outcomes will include all-cause mortality, new event of acute myocardial infarction, stroke (haemorrhagic and ischaemic), hospitalisation for acute coronary syndrome and urgent revascularisation procedures. Risk of bias will be assessed using the Cochrane Risk of Bias assessment instrument for RCTs and the Strengthening the Reporting of Observational Studies in Epidemiology instrument for observational studies. Network meta-analysis will be performed using multivariate random-effects meta-regression models. The surface under the cumulative ranking curve will be used to provide a hierarchy of ADDs that increase cardiovascular mortality.

DISSEMINATION

The results of this study will be presented at a professional conference and submitted to a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017051220.

Habitual sleep and kidney function in chronic kidney disease: the Chronic Renal Insufficiency Cohort study

Physiological evidence suggests that sleep modulates kidney function. Our objective was to examine the cross-sectional association between kidney function and objectively-estimated habitual sleep duration, quality and timing in a cohort of patients with mild to moderate chronic kidney disease. This study involved two US clinical centers of the Chronic Renal Insufficiency Cohort (CRIC) study, including 432 participants in a CRIC ancillary sleep study. Habitual sleep duration, quality and timing were measured using wrist actigraphy for 5-7 days. Validated sleep questionnaires assessed subjective sleep quality, daytime sleepiness and risk of sleep apnea. Kidney function was assessed with the estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration equation, and the urinary protein to creatinine ratio. Lower estimated glomerular filtration rate was associated with shorter sleep duration (-1.1 mL min^-1  1.73 m^-2 per hour less sleep, P = 0.03), greater sleep fragmentation (-2.6 mL min^-1  1.73 m^-2 per 10% higher fragmentation, P < 0.001) and later timing of sleep (-0.9 mL min^-1  1.73 m^-2 per hour later, P = 0.05). Higher protein to creatinine ratio was also associated with greater sleep fragmentation (approximately 28% higher per 10% higher fragmentation, P < 0.001). Subjective sleep quality, sleepiness and persistent snoring were not associated with estimated glomerular filtration rate or protein to creatinine ratio. Thus, worse objective sleep quality was associated with lower estimated glomerular filtration rate and higher protein to creatinine ratio. Shorter sleep duration and later sleep timing were also associated with lower estimated glomerular filtration rate. Physicians treating patients with chronic kidney disease should consider inquiring about sleep and possibly sending for clinical sleep assessment. Longitudinal and interventional trials are needed to understand causal direction.

Direct and indirect cost of managing alzheimer's disease and related dementias in the United States

INTRODUCTION

Care of individuals with Alzheimer's Disease and Related Dementias (ADRD) poses special challenges. As the disease progresses, individuals with ADRD require increasing levels of medical care, caregiver support, and long-term care which can lead to substantial economic burden. Areas covered: In this expert review, we synthesized findings from studies of costs of ADRD in the United States that were published between January 2006 and February 2017, highlighted major sources of variation in costs, identified knowledge gaps and briefly outlined directions for future research and implications for policy and program planning. Expert commentary: A consistent finding of all studies comparing individuals with and without ADRD is that the average medical, non-medical, and indirect costs of individuals with ADRD are higher than those without ADRD, despite the differences in the methods of identifying ADRD, duration of the study, payer type and settings of study population. The economic burden of ADRD may be underestimated because many components such as direct non-medical costs for home safety modifications and adult day care services and indirect costs due to the adverse impact of ADRD on caregivers' health and productivity are not included in cost estimates.

Is Signature Size Associated With Organ Donor Designation on Driver's Licenses?

INTRODUCTION

Previous studies suggest that large signature size is associated with narcissistic characteristics. By contrast, organ donation is an indicator of altruism. Because altruism and narcissism may be viewed as opposites, we sought to determine if smaller signature size is associated with willingness to be an organ donor.

METHODS

Using a cross-sectional study design, we reviewed the health records of 571 randomly selected primary care patients at a large urban safety-net medical system to obtain their demographic and medical characteristics. We also examined driver's licenses that were scanned into electronic health records as part of the patient registration process. We measured signature sizes and obtained the organ donor designation from these driver's licenses.

RESULTS

Overall, 256 (45%) patients were designated as donors on their driver's licenses. Signature size averaged 113.3 mm(2) but varied greatly across patients (10th percentile 49.1 mm(2), 90th percentile 226.1 mm(2)). On multivariate analysis, donor designation was positively associated with age 18-34 years, non-black race, having private insurance, and not having any comorbid conditions. However, signature size was not associated with organ donor designation.

CONCLUSIONS

Signature size is not associated with verified organ donor designation. Further work is needed to understand the relationship between personality types and willingness to be an organ donor.

Prominent impact of community risk factors on kidney transplant candidate processes and outcomes

Numerous factors impact patients' health beyond traditional clinical characteristics. We evaluated the association of risk factors in kidney transplant patients' communities with outcomes prior to transplantation. The primary exposure variable was a community risk score (range 0-40) derived from multiple databases and defined by factors including prevalence of comorbidities, access and quality of healthcare, self-reported physical and mental health and socioeconomic status for each U.S. county. We merged data with the Scientific Registry of Transplant Recipients (SRTR) and utilized risk-adjusted models to evaluate effects of community risk for adult candidates listed 2004-2010 (n = 209 198). Patients in highest risk communities were associated with increased mortality (adjusted hazard ratio [AHR] = 1.22, 1.16-1.28), decreased likelihood of living donor transplantation (adjusted odds ratio [AOR] = 0.90, 0.85-0.94), increased waitlist removal for health deterioration (AHR = 1.36, 1.22-1.51), decreased likelihood of preemptive listing (AOR = 0.85, 0.81-0.88), increased likelihood of inactive listing (AOR = 1.49, 1.43-1.55) and increased likelihood of listing for expanded criteria donor kidneys (AHR = 1.19, 1.15-1.24). Associations persisted with adjustment for rural-urban location; furthermore the independent effects of rural-urban location were largely eliminated with adjustment for community risk. Average community risk varied widely by region and transplant center (median = 21, range 5-37). Community risks are powerful factors associated with processes of care and outcomes for transplant candidates and may be important considerations for developing effective interventions and measuring quality of care of transplant centers.

Abstract P6-04-10: Genetic Discrimination of Aggressive from Indolent DCIS

Background: Treatment options for DCIS vary from surgical excision with or without radiation and/or chemopreventive therapy, or mastectomy. Intuitively, more aggressive treatment options should lead to improved survival rates, however, studies have shown no difference in breast cancer mortality between women treated with wide excision only versus those with excision plus radiation and treatments can be costly, lengthy and associated with side effects. To avoid over-treating women with indolent disease, while intensively treating women with aggressive disease, new molecular tools must be developed to supplement pathological information to classify DCIS lesions and predict clinical outcome.

Methods: Formalin-fixed paraffin-embedded (FFPE) pure DCIS biopsy specimens were collected from the pathology archives of the Anne Arundel Medical Center. Samples included those with poor prognosis characterized by either recurrence of DCIS or progression to invasive cancer (n=7) and those good prognosis, having ≥5-year disease-free survival (n=10). RNA was isolated after laser-microdissection of pure tumor cells and hybridized to Breast Cancer DSA™ microarrays (Almac Diagnostics). S-way ANOVA was used to account for batch effects and then Support Vector Machine (SVM) was used to identify candidate genes effective at discriminating good from poor prognosis DCIS. Pathway analysis was performed using MetaCore (GeneGeo).

Results: 328 genes were found to be differentially expressed between good and poor prognosis specimens (P&lt;0.01). Preliminary analysis with SVM found that a 70-gene candidate signature from these 328 genes wasoptimal under the tested conditions for discriminating favorable from poor prognosis DCIS. This candidate signature included genes such as MEF2C, PTK2 and ZBTB2. Pathway analysis revealed that genes involved in cytoskeleton modeling, apoptosis and survival, DNA damage repair and cell adhesion are expressed at lower levels in poor prognosis DCIS while those involved in cell cycle, immune response and cell proliferation are expressed at higher levels.

Conclusions: While studies have attempted to identify molecular profiles associated with aggressive DCIS by comparing DCIS co-occurring with invasive disease to pure DCIS, to our knowledge, this is the first study that identified a candidate molecular signature of prognosis in pure DCIS. Although many of the 70 genes found to differ between favorable and poor prognosis DCIS have not been previously associated with breast cancer or have unknown function, MEF2C and PTK2 have been implicated in invasion and migration, while ZBTB2 is a master regulator of p53 and stimulates cellular proliferation. These data demonstrate aggressive DCIS do differ from indolent DCIS at the genetic level and that these differences may be useful in developing molecular tools to classify DCIS lesions and guide appropriate treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-04-10.

Crystal structure of the anti-(carcinoembryonic antigen) single-chain Fv antibody MFE-23 and a model for antigen binding based on intermolecular contacts

MFE-23 is the first single-chain Fv antibody molecule to be used in patients and is used to target colorectal cancer through its high affinity for carcinoembryonic antigen (CEA), a cell-surface member of the immunoglobulin superfamily. MFE-23 contains an N-terminal variable heavy-chain domain joined by a (Gly(4)Ser)(3) linker to a variable light-chain (V(L)) domain (kappa chain) with an 11-residue C-terminal Myc-tag. Its crystal structure was determined at 2.4 A resolution by molecular replacement with an R(cryst) of 19.0%. Five of the six antigen-binding loops, L1, L2, L3, H1 and H2, conformed to known canonical structures. The sixth loop, H3, displayed a unique structure, with a beta-hairpin loop and a bifurcated apex characterized by a buried Thr residue. In the crystal lattice, two MFE-23 molecules were associated back-to-back in a manner not seen before. The antigen-binding site displayed a large acidic region located mainly within the H2 loop and a large hydrophobic region within the H3 loop. Even though this structure is unliganded within the crystal, there is an unusually large region of contact between the H1, H2 and H3 loops and the beta-sheet of the V(L) domain of an adjacent molecule (strands DEBA) as a result of intermolecular packing. These interactions exhibited remarkably high surface and electrostatic complementarity. Of seven MFE-23 residues predicted to make contact with antigen, five participated in these lattice contacts, and this model for antigen binding is consistent with previously reported site-specific mutagenesis of MFE-23 and its effect on CEA binding.

Loss of myocardial protection from ischemic preconditioning following chronic exposure to R(-)-N6-(2-phenylisopropyl)adenosine is related to defect at the adenosine A1 receptor

Exogenously administered adenosine agonist will protect myocardium against infarction during ischemia. However, long-term exposure to adenosine agonists is associated with loss of this protection. To determine why this protection is lost, isolated, perfused rabbit hearts were studied after administration of R(-)-N6-(2-phenylisopropyl)adenosine (PIA), 0.25 mg/h IP, for 3-4 days to intact animals. All hearts experienced 30 min of regional ischemia and 120 min of reperfusion. Control groups 1 and 2 were untreated. In group 1 this ischemia/reperfusion was the only intervention, whereas group 2 hearts were preconditioned with a cycle of 5 min global ischemia/10 min reperfusion preceding the 30 min regional ischemia. Groups 3-5 had been chronically exposed to PIA. Group 3 hearts had 1 preconditioning ischemia/reperfusion cycle before the prolonged ischemia. Group 4 received a 5 min infusion of 0.1 micromol/L phenylephrine in lieu of global ischemia, whereas group 5 was instead treated with 1 micromol/L carbachol. Infarct size averaged 32% of the risk zone in group 1, whereas ischemic preconditioning limited infarction to 8.2% in group 2. Prolonged exposure of group 3 hearts to PIA resulted in the inability of preconditioning with 5 min global ischemia to protect (28.7+/-4.4% infarction). However, protection was restored by either phenylephrine, an agonist of alpha1-adrenergic receptors which couple to Gq and stimulate PKC, or carbachol, an agonist of M2-muscarinic receptors which couple instead to Gi as do adenosine A1 receptors (5.2+/-1.7% and 9.2+/-2.1% infarction, resp.). Therefore, cross tolerance to ischemic preconditioning develops after chronic PIA infusion. Since both the Gi and the PKC components of the preconditioning pathway were shown to be intact, tolerance must have been related to downregulation or desensitization of the A1 adenosine receptor.

Comparison of debris extruded apically in straight canals: conventional filing versus profile .04 Taper series 29

The purposes of this study were to determine quantitatively the amount of debris and irrigant forced in an apical direction, the frequency of apical plug development, and the time required to prepare canals when a step-back technique using K-files was compared with the .04 Taper system. Sixty-nine extracted teeth with straight canals were divided into four statistically similar groups. Two groups were instrumented either 1 mm short of the apical foramen or to the apical foramen with K-files. The other two groups were instrumented to the same levels using .04 Taper files. The extruded debris and irrigant were collected in preweighed vials. The weight of the debris and volume of irrigant extruded using both techniques were compared and analyzed using paired t test and one-way ANOVA. Tukey's Multiple Comparisons Procedure showed K-files used to the apical foramen extruded significantly more debris than the other three groups (p < 0.01). The .04 Taper files used 1 mm short extruded less debris than the other groups. Significantly more irrigant was extruded when filing was performed to the apical foramen (p < 0.007), regardless of the technique used. More apical plugs were created in teeth filed short of the apical foramen, but the difference between the two preparation techniques was not statistically significant. It took significantly less time to instrument canals with the .04 Taper system than with K-files (p < 0.002).

Intravenous co-infusion of adenosine and norepinephrine preconditions the heart without adverse hemodynamic effects

OBJECTIVE

A simple intervention is needed that could protect the heart against infarction during limited-access coronary artery bypass grafting. Adenosine and norepinephrine can precondition the heart with resulting protection, but adverse hemodynamic effects prevent clinical application. Because heart rate, blood pressure, and contractility effects of these two drugs are diametrically opposite, a mixture might be beneficial.

METHODS

A superficial branch of the left coronary artery of rabbits was surrounded with a suture. Infarction was produced in all hearts by a 30-minute coronary artery occlusion. Infarct size after reperfusion was measured and is presented as a percentage of the risk zone. The effect of 5-minute intravenous co-infusion of adenosine (20 mg/kg) and norepinephrine (0.1 mg/kg) 15 minutes before ischemia was examined. In addition, the protective effect of three sequential intravenous bolus injections of adenosine at either 0.2 or 0.4 mg/kg was evaluated.

RESULTS

Thirty minutes of regional ischemia caused infarction of 40% +/- 4% of the risk zone. The combination of adenosine and norepinephrine caused no change in blood pressure but rather protected the heart, with infarction of only 9% +/- 2% of the risk zone (p = 0.0001 vs control). Adenosine-norepinephrine co-infusion still protected the heart when the interval between infusion and ischemia was extended to 60 minutes, but it did not protect with a 120-minute interval. Intravenous bolus injections of adenosine resulted in cardiac slowing and marked hypotension. Boluses of 0.2 mg/kg resulted in a minimal, but significant, reduction in infarct size, whereas the higher dose provided no protection.

CONCLUSION

Adenosine-norepinephrine co-infusion provides a feasible and safe parenteral method for preconditioning the heart.

Extended glycoprotein structure of the seven domains in human carcinoembryonic antigen by X-ray and neutron solution scattering and an automated curve fitting procedure: implications for cellular adhesion

Carcinoembryonic antigen (CEA) is one of the most widely used cell-surface tumour markers for tumour monitoring and for targeting by antibodies. It is heavily glycosylated (50% carbohydrate) and a monomer is constructed from one V-type and six C2-type fold domains of the immunoglobulin superfamily. The solution arrangement at low resolution of the seven domains in CEA cleaved from its membrane anchor was determined by X-ray and neutron scattering. Guinier analyses showed that the X-ray radius of gyration RG of CEA was 8.0 nm. The length of CEA was 27 to 33 nm, and is consistent with an extended arrangement of seven domains. The X-ray cross-sectional radius of gyration RXS was 2.1 nm, and is consistent with extended carbohydrate structures in CEA. The neutron data gave CEA a relative molecular mass of 150,000, in agreement with a value of 152,500 from composition data, and validated the X-ray analyses. The CEA scattering curves were analysed using an automated computer modelling procedure based on the crystal structure of CD2. The V-type and C2-type domains in CD2 were separated, and the C2-type domain was duplicated five times to create a linear seven-domain starting model for CEA. A total of 28 complex-type oligosaccharide chains in extended conformations were added to this model. By fixing the six interdomain orientations to be the same, three-parameter searches of the rotational orientations between the seven domains gave 4056 possible CEA models. The best curve fits from these corresponded to a family of zig-zag models. The long axis of each domain was set at 160(+/-25) degrees relative to its neighbour, and the two perpendicular axes were orientated at 10(+/-30) degrees and -5(+/-35) degrees. Interestingly, the curve fit from this model is within error of that calculated from a CEA model generated directly from the CD2 crystal structure by the superposition of adjacent domains. Zig-zag models of this type imply that the protein face of the GFCC' beta-sheet in neighbouring CEA domains lie on alternate sides of the CEA structure. Such a model has implications for the adhesion interactions between CEA molecules on adjacent cells or for the antibody targeting of CEA.

Procoagulant activity on injured arteries and associated thrombi is mediated primarily by the complex of tissue factor and factor VIIa

BACKGROUND

Rethrombosis limits the efficacy of coronary thrombolysis and may result from surface-associated thrombin, de-novo prothrombin activation, or both. This study was designed to determine the relative roles of thrombin, factor Xa, and the complex of tissue factor and factor VIIa in the procoagulant activity on injured arteries with evolving thrombi.

METHODS

Extensive vascular injury and platelet-rich thrombi were induced in the abdominal aorta of 25 anesthetized rabbits by applying anodal current through a transluminal electrode for 3 h. Injured vessel segments were excised and placed in a chamber permitting perfusion over the luminal surface and associated thrombus.

RESULTS

Vessel segments perfused with recalcified, citrated human plasma induced marked increases in the concentration of fibrinopeptide A, a marker of thrombin-induced fibrin formation, in the effluent plasma after 10 min (4636 +/- 1894% of fibrinopeptide A in the nonperfused plasma, n = 5). Perfusion with plasma depleted of vitamin K-dependent coagulation factors prevented the increase in fibrinopeptide A (122 +/- 30%, n = 4), indicating the lack of preformed functional thrombin. Furthermore, appearance of fibrinopeptide A was attenuated by perfusion with plasma containing 0.1 mumol/l recombinant tick anticoagulant peptide, a specific inhibitor of factor Xa (594 +/- 320%, n = 3), and by preincubation of vessel segments with a monoclonal antibody to rabbit tissue factor (438 +/- 220%, n = 3).

CONCLUSIONS

Procoagulant activity on injured vessels and associated thrombi is mediated by factor Xa, a product of the functional initiation of coagulation by factor VIIa associated with tissue factor. Accordingly, inhibition of tissue factor-mediated coagulation may be effective for attenuation of active thrombogenesis on injured vessels and during thrombolysis.

Hypoxia preconditions rabbit myocardium by an adenosine receptor-mediated mechanism

OBJECTIVES

To test the ability of hypoxia without reoxygenation to precondition myocardium and to test a possible involvement of adenosine receptors in that response.

DESIGN

Isolated rabbit hearts were perfused with oxygenated Krebs-Henseleit buffer. Control hearts underwent 30 min regional ischemia followed by 2 h reperfusion. A second group received 10 min global perfusion with hypoxic buffer (PO2 = 33 +/- 3 mmHg) immediately before coronary occlusion. A third group was subjected to a similar protocol as group 2, with the adenosine receptor blocker 8-(p-sulfophenyl) theophylline (SPT) (100 microM) added to the buffer immediately before and throughout hypoxia. At the end of reperfusion the area at risk for infarction was determined by fluorescent particles while infarction size was measured by triphenyltetrazolium staining.

RESULTS

Hearts without hypoxic perfusion preceding ischemia experienced 38.2 +/- 2.4% infarction. The hypoxic group, despite a longer total period of oxygen deprivation, had only 21.0 +/- 4.2% infarction (P < or = 0.05). SPT blocked the protection (42.1 +/- 6.9% infarction).

CONCLUSIONS

Hypoxia without subsequent reoxygenation before ischemia protected the heart from infarction, indicating that reoxygenation may not be the critical feature of reperfusion typically employed in an ischemic preconditioning protocol. Because adenosine receptor blockade abolishes the protection from hypoxic perfusion, the mechanism of this protection may be similar to that seen with ischemic preconditioning.

Ketamine-xylazine anaesthesia permits a KATP channel antagonist to attenuate preconditioning in rabbit myocardium

OBJECTIVE

ATP sensitive potassium (KATP) channels have been implicated in the mechanism of ischaemic preconditioning, though apparently not in the pentobarbitone anaesthetised rabbit model. The aim of this study was to test whether potassium channel activation and blockade would alter protection in ketamine-xylazine anaesthetised rabbits.

METHODS

In situ rabbit hearts (n = 50) received 30 min regional ischaemia and 3 h reperfusion. Some hearts were preconditioned by 5 min regional ischaemia and 10 min reperfusion prior to the long ischaemia. Infarct size was determined by tetrazolium staining.

RESULTS

In rabbits anaesthetised with ketamine-xylazine, brief preconditioning ischaemia continued to produce much smaller infarcts than in non-preconditioned animals [19(SEM 2)% v 47(3)%, p < or = 0.05]. blocking KATP channels by pretreating with glibenclamide resulted in 35(3)% infarction in non-preconditioned hearts and aborted protection in preconditioned hearts [35(4)% infarction]. Substituting the potassium channel activator pinacidil for the short ischaemia caused comparable reductions in infarct size [28(4)%, p < or = 0.05 v non-preconditioned hearts]. This protection, however, could be blocked by concomitant administration of the adenosine receptor blocker 8-(p-sulphophenyl)theophylline (SPT) [44(3)% infarction].

CONCLUSIONS

When ketamine-xylazine anaesthesia was employed, the protective effects of ischaemic preconditioning in the rabbit heart could be blocked by glibenclamide, and pinacidil could mimic the protection of ischaemic preconditioning. Because the protection afforded by pinacidil could be blocked by SPT, however, there is still some question whether the KATP channel is the end effector of preconditioning.

Catecholamines can induce adenosine receptor-mediated protection of the myocardium but do not participate in ischemic preconditioning in the rabbit

The role of catecholamines in ischemic preconditioning is unclear. Accordingly, the effects of tyramine-induced norepinephrine release and alpha 1-receptor blockade were examined. Ischemic preconditioning with a 5-minute coronary occlusion 10 minutes before a 30-minute ischemic interval resulted in only 7.7 +/- 3.1% infarction of the risk area, significantly less than that in control rabbits with isolated 30-minute coronary occlusions (34.4 +/- 3.2%, P < .01). Intravenous infusion of tyramine 10 minutes before 30 minutes of ischemia also protected the heart from infarction to an extent similar to that seen with ischemic preconditioning (6.9 +/- 2.4% infarction). This protection observed with tyramine infusion was eliminated by alpha 1-receptor blockade with BE 2254 (36.8 +/- 2.6% infarction) but was unaffected by beta-blockade with propranolol (10.5 +/- 2.4% infarction). Furthermore, the protection was unaffected when the tyramine-induced hypertension was attenuated by allowing blood to flow into a volume reservoir (3.9 +/- 0.8% infarction, P < .01 vs control value). The nonselective adenosine-receptor blocker PD 115,199 also eliminated tyramine-induced protection (40.2 +/- 5.6% infarction), indicating that adenosine is involved in adrenergic-mediated protection. BE 2254 could not block ischemic preconditioning (3.9 +/- 1.1% infarction, P < .01 vs control value). Therefore, catecholamine release before prolonged ischemia can protect the heart from infarction via the alpha 1-receptor, but adenosine receptor stimulation is also involved. alpha-Adrenergic stimulation does not appear to be critical to the protection observed after ischemic preconditioning.

Hyperbaric oxygen limits infarct size in ischemic rabbit myocardium in vivo

BACKGROUND

We explored the ability of increased oxygen pressure to modify necrosis in an open-chest rabbit model of myocardial ischemia and reperfusion.

METHODS AND RESULTS

A branch of the left coronary artery was occluded for 30 minutes followed by 3 hours of reperfusion. Infarction was measured by triphenyl tetrazolium staining and expressed as a percentage of the ischemic zone. Untreated rabbits were ventilated with 100% oxygen at 1 atm absolute. Treatment animals were exposed to hyperbaric oxygen at 2.5 atm absolute. The 1.0-atm control hearts developed 41.5 +/- 4.6% infarction of the ischemic zone. Animals exposed to hyperbaric oxygen during ischemia only, reperfusion only, or ischemia and reperfusion had significantly smaller infarcts with respect to control animals (16.2 +/- 2.9%, 14.5 +/- 3.7%, and 9.8 +/- 2.7%, respectively; P < or = .01), indicating that they had been protected by the procedure. When hyperbaric oxygen was begun 30 minutes after the onset of reperfusion, no protection was seen (35.8 +/- 3.8%).

CONCLUSIONS

We conclude that hyperbaric oxygen limits infarct size in the reperfused rabbit heart and that the effect can be achieved when hyperbaric oxygen is begun at reperfusion.

Streptozotocin-induced non-insulin-dependent diabetes protects the heart from infarction

BACKGROUND

The vulnerability of the myocardium of a diabetic animal to an ischemic insult is controversial. To address this issue, streptozotocin-induced non-insulin-dependent diabetes (NIDD) was induced in rats, and the effects of regional myocardial ischemia were assessed by measuring infarct size.

METHODS AND RESULTS

Open-chest rats with NIDD and age-matched control rats underwent 30 or 45 minutes of regional ischemia and 2-hour reperfusion. Infarct size was measured by tetrazolium. Control rats had 32.0 +/- 3.3% infarction of the risk zone after a 30-minute coronary occlusion, whereas NIDD rats had significantly smaller infarcts (11.5 +/- 3.1% of the risk area, P < .005). When ischemic time was extended to 45 minutes, infarct size in control animals averaged 57.9 +/- 6.2%, whereas only 37.3 +/- 5.6% of ischemic myocardium was infarcted in NIDD rats (P < .05). In a subset NIDD group, rats experienced a period of ischemic preconditioning (three cycles of 5-minute ischemia/5-minute reperfusion) before 45-minute ischemia. Infarct size in these rats averaged only 6.9 +/- 3.0% (P < .01 vs nonpreconditioned NIDD rats with 45-minute coronary occlusions). Collateral flow was measured in NIDD rat hearts with radioactive microspheres. Collateral flow was < 1% of normal myocardial blood flow.

CONCLUSIONS

We conclude that NIDD protects the heart from infarction and that this protection is not related to the development of coronary collaterals. Furthermore, preconditioning can further protect the NIDD heart.

Effect of adenosine receptor blockade: preventing protective preconditioning depends on time of initiation

Ischemic preconditioning protects the rabbit myocardium from infarction from a subsequent ischemia, and adenosine receptors appear to be involved in this protection. The present study attempts to determine when adenosine receptors must be occupied to achieve protection by infusing the adenosine receptor antagonist PD-115,199 at various time points during the study. Open-chest rabbits were subjected to 30 min of regional ischemia followed by 3 h of reperfusion and had 38 +/- 4% infarction of the risk zone. When hearts were preconditioned by 5 min of ischemia and 10 min reperfusion before the 30-min period of ischemia, only 9 +/- 2% infarction occurred. PD-115,199 given 5 min before the ischemic preconditioning episode blocked the protective effect of preconditioning (39 +/- 5% infarction). PD-115,199 also blocked the protection when given between the ischemic preconditioning episode and the 30-min period of ischemia (30 +/- 4% infarction). PD-115,199 given at the end of 30 min of ischemia did not block protection in preconditioned (PC) hearts (17 +/- 5% infarction) and had no effect on non-PC hearts (44 +/- 6% infarction). In prior studies we found that exogenous adenosine could substitute for ischemia to precondition the heart, indicating that adenosine is an initiator of preconditioning. These results, however, indicate that adenosine receptors must also be occupied during the long ischemic period for preconditioning to be protective and suggest that adenosine is a mediator of preconditioning as well.

The protection of ischaemic preconditioning can be reinstated in the rabbit heart after the initial protection has waned

OBJECTIVE

Preconditioning the heart with 5 min of ischaemia followed by reperfusion renders the myocardium resistant to infarction from subsequent ischaemia. This protection lasts for about 1 h. The aim of this study was to test whether the protection could be reinstated with a second episode of preconditioning after protection from an initial episode had worn off.

METHODS

To induce infarction animals experienced 30 min of coronary artery occlusion and then 3 h reperfusion. Ischaemic preconditioning was accomplished with 5 min of coronary branch occlusion. In one group of rabbits the subsequent reperfusion period was prolonged to 2 h to permit protection to wear off before the 30 min coronary occlusion was initiated. In another group a second 5 min coronary occlusion was performed at the end of the 2 h reperfusion. After 10 min of reperfusion the 30 min ischaemic period began. Control animals experienced only the 30 min ischaemia and 3 h reperfusion. Infarct volume was measured with tetrazolium and expressed as a percentage of the ischaemic zone volume.

RESULTS

Average infarct size in seven control rabbits [36.0 (SEM 2.0)% of the ischaemic zone] was not significantly different from that in eight rabbits with the prolonged coronary occlusion occurring 2 h after the preconditioning stimulus [28.6 (2.9)% infarction]. In contrast infarcts were significantly smaller in the re-preconditioned group of seven rabbits [8.3 (4.2)%] and comparable to those previously seen with a single preconditioning stimulus followed 10 min later by the 30 min occlusion [6.1 (1.8)%].

CONCLUSIONS

The rabbit heart can be protected with a second preconditioning stimulus after protection from an initial period of preconditioning has subsided.

Pretreatment with pertussis toxin blocks the protective effects of preconditioning: evidence for a G-protein mechanism

We tested whether a pertussis toxin-sensitive G-protein mediates the protective effects of preconditioning. Thirty-one small (1 kg) rabbits were used. All rabbits experienced 30 min regional myocardial ischaemia followed by 3 h reperfusion. Infarct size was determined by tetrazolium. The percentage of the risk zone which infarcted in controls was 37.4 +/- 4.6%. Preconditioning with a 5 min occlusion followed by 10 min reperfusion prior to the 30 min ischaemic insult protected against infarction (5.2 +/- 2.1% infarction). 25 micrograms/kg pertussis toxin, administered 48 h prior to surgery, blocked G-protein signal transduction as tested by challenge with iv acetylcholine which normally slows the heart. Pertussis toxin treatment had no effect on infarct size in non-preconditioned rabbits (37.6 +/- 4.7% infarction) but blocked protection in preconditioned rabbits (27.3 +/- 4.3% infarction). To test the involvement of G-proteins further in preconditioning, we tested the ability of the M2 agonist carbachol to substitute for ischaemic preconditioning and protect the heart from infarction. Rabbits hearts were excised and perfused with Kreb's buffer. Control animals subjected to 30 min of regional ischaemia and 2 h reperfusion yielded 29.4 +/- 2.9% infarction. Preconditioning with 5 min global ischaemia and 10 min reperfusion prior to the 30 min regional ischaemia significantly protected the isolated heart from infarction (8.41 +/- 3.26% infarction). Carbachol, infused for 5 min at 1 microM concentration, protected the hearts as well as preconditioning, yielding 8.90 +/- 2.08% infarction. We conclude that preconditioning involves a pertussis toxin-sensitive G-protein and that the same G-protein couples to muscarinic M2 receptors.

Blockade of ATP-sensitive potassium channels increases infarct size but does not prevent preconditioning in rabbit hearts

Ischemic preconditioning renders the heart resistant to infarction by an unknown mechanism. This study tests whether preconditioning may be working through activation of ATP-sensitive potassium channels. If that were the case, then blockade of the channels should eliminate preconditioning's protection, and activation of these channels should mimic it. Thirty minutes of regional coronary ischemia followed by 3 hours of reperfusion caused 38.0 +/- 3.7% of the risk zone to become infarcted in control rabbits. Preconditioning with 5-minute ischemia followed by a 10-minute reperfusion before the 30-minute insult caused only 8.8 +/- 2.1% infarction, which was a reduction of 29.2% in infarct size by preconditioning (p < 0.01 versus control value). Pretreatment with the potassium channel blocker glibenclamide at three different concentrations significantly elevated infarct size in the nonpreconditioned hearts at all doses. Preconditioning, however, continued to limit infarct size by an amount not different from that seen in the control group at all doses of glibenclamide. Pinacidil, a potassium channel agonist, given before a 30-minute ischemic insult resulted in infarct sizes no different from that seen in nonpreconditioned control rabbits. We conclude that ATP-sensitive potassium channels are not involved in preconditioning in the rabbit heart; however, blocking those channels does exacerbate ischemia.

Intravenous pretreatment with A1-selective adenosine analogues protects the heart against infarction

BACKGROUND

Recent data from this laboratory indicate that pretreatment with adenosine can protect the heart against infarction via A1-receptors, but because of systemic hypotension, adenosine had to be given into the coronary circulation.

METHODS AND RESULTS

In this study, we tested whether the protection could be achieved by intravenous administration of the A1-selective adenosine agonists N6-(phenyl-2R-isopropyl)-adenosine (PIA) and 2-chloro-N6-cyclopentyladenosine (CCPA). Nine groups of open-chest anesthetized rabbits were subjected to 30 minutes of regional coronary ischemia and 3 hours of reperfusion. Infarct size was determined by tetrazolium staining. Control hearts receiving no treatment had 38 +/- 4% of the risk zone infarcted. Preconditioning with 5 minutes of ischemia and 10 minutes of reperfusion before ischemia limited the infarct to 8 +/- 4%. Intravenous PIA 15 minutes before 30-minute ischemia also limited infarct size to 6 +/- 2% at the highest dose. CCPA offered similar protection. When the PIA was given at reperfusion, infarct size was 46 +/- 6%, indicating that receptor activation must precede ischemia to protect. Pretreatment with CGS 21680, a selective A2-receptor agonist, caused identical hypotension but failed to limit infarct size (43 +/- 3%), indicating again that the A1-receptor is involved. When rabbits pretreated with PIA were paced at 220 beats per minutes, PIA still limited infarct size (16 +/- 4%), indicating that protection was not the result of bradycardia.

CONCLUSIONS

These results indicate that stimulation of adenosine A1-receptors causes the heart to become resistant to ischemia and that this protection can be achieved with intravenous administration of A1-selective agents.

Leucogyrophana pinastri, a wood decay fungus as a probable cause of an extrinsic allergic alveolitis syndrome

Two patients were suspected of having extrinsic allergic alveolitis due to exposure to an agent in their home environment. On inspection of their houses, fungal decay was evident in the floorboards, and fungal spores were found deposited on many surfaces. The decay fungus was later identified as Leucogyrophana pinastri. Using an extract of the fruiting bodies and mycelium of this fungus, precipitating antibodies were identified in the sera of both patients. Based on the known exposure by the two patients to these small spores, the absence of a likely alternative allergen, the similarity between these two cases, and the positive precipitin test results, L. pinastri was considered to be the most likely cause of extrinsic allergic alveolitis in our cases.