Abstract 35: 30-Day Risk-Standardized Mortality and Readmission after Ischemic Stroke in Critical Access Hospitals

Background: Critical access hospital (CAH) designation identifies hospitals providing emergency and inpatient care to residents of rural communities. Patients with cardiovascular disease and pneumonia have poorer outcomes at CAHs, but stroke outcomes have not been assessed.

Objective: Compare risk-adjusted 30-day mortality and readmission rates after ischemic stroke for patients treated at critical access and non-critical access hospitals.

Methods: The cohort included all fee-for-service Medicare beneficiaries 65+ years of age discharged with a primary diagnosis of ischemic stroke (ICD-9 433, 434, 436) in 2006. Risk-standardized mortality and readmission rates at 30 days were compared for patients treated at CAH versus other hospitals using hierarchical logistic regression models, adjusted for patient demographics, medical history, and comorbid conditions.

Results: There were 10,267 ischemic stroke discharges from 1,165 CAHs and 300,114 discharges from 3,381 non-CAHs. Patients discharged from CAHs were older, more often women and white, and generally had more comorbid conditions. CAHs had higher unadjusted in-hospital (6.4% vs. 4.6%, p<0.001) and 30-day (19.9% vs. 10.9%, p<0.001) mortality rates than non-CAHs, but lower 30-day all-cause readmission (12.4% vs. 13.8%, p<0.001). In risk-standardized analyses, the differences were less marked for 30-day mortality (CAHs vs. non-CAHs; 11.9%±1.4% vs. 10.9%±1.7%, p<0.001), with no difference in 30-day readmission (13.7%±0.6% vs. 13.7%±1.4%, p=0.2787).

Conclusions: Although there were no differences in readmission rates, stroke patients discharged from CAHs had higher unadjusted mortality than those discharged from non-CAHs. These differences, however, were at least partially explained by differences in patient characteristics. Further research is needed to identify factors contributing to these differences.

Abstract 3376: Utilization of Physician Services within the First Month after Hospitalization for Ischemic Stroke

Background: Stroke poses significant burdens on patients, their families, and informal caregivers in the days following hospitalization. Limited data are available assessing patient use of immediate poststroke outpatient services. Service utilization patterns have implications for understanding continuity of care and may affect 30-day mortality and readmission rates, measures being used in other conditions as indicators of the quality and efficiency of hospital-leve care.

Objective: To determine physician specialty, frequency, and most common reasons for physician office visits for Medicare beneficiaries within 30 days of hospital discharge after an ischemic stroke.

Methods: Data were derived by linking a 5% sample of Part B Medicare data (physician carrier file) with Part A inpatient data. The study cohort included fee-for-service beneficiaries 65+ years of age with a primary discharge diagnosis of ischemic stroke (ICD-9 433, 434, 436) in 2006 with linked in-patient and physician visit data. The 10 most frequent reasons for physician office visits were identified using principal ICD-9 diagnosis codes. Physician specialty was identified using the CMS provider specialty code.

Results: Among 10,230 identified ischemic stroke patients, 9,523 were discharged alive and included in the study. Of these patients, 16% were rehospitalized for any cause, 42% had at least one hospital outpatient visit, and 88% had at least one physician office visit within 30 days. Primary reasons for physician office visits included stroke, atrial fibrillation, hypertension, diabetes, and heart failure ( Table ). Internists were seen most frequently, followed by radiologists, cardiologists, and family practice physicians. There were 1,449 visits to neurologists and 1,355 visits to physical medicine and rehabilitation physicians.

Conclusion: Almost 90% of Medicare beneficiaries discharged with ischemic stroke were seen in a physician’s office within the first month. Reasons for visits included stroke as well as other cardiovascular conditions and common stroke risk factors. Additional research is needed to determine the accuracy of physician codes for follow-up visits as well as to assess how the utilization of outpatient services within the early recovery period influences 30-day mortality and readmission rates.

Abstract 33: Seasonal Patterns in Risk-Standardized Mortality after Ischemic Stroke: A Winter and July Effect

Background: A recent systematic review found that mortality rates were higher and efficiency of care lower in hospitals coincident with the introduction of new trainees in July, but there was significant heterogeneity in study quality, and none of the included studies focused on stroke care.

Purpose: To assess seasonal variation in 30-day risk-standardized mortality rates (RSMRs) for elderly ischemic stroke patients from 1999 to 2006 and determine whether patterns differ for patients discharged from teaching versus non-teaching hospitals.

Methods: The study cohort included all fee-for-service Medicare beneficiaries aged 65 years and older discharged with an ischemic stroke (ICD-9 primary codes 433, 434, 436) from 1999 to 2006 in the United States. A hierarchical logistic regression model fitted annual data to estimate the 30-day RSMR, adjusted for demographic and clinical characteristics. The annual datasets were combined and reconstructed to time series analyses, with month as a unit. The time series analysis included 96 months; RSMRs were calculated for each month. The unobserved components modeling approach was used to fit the time series data with risk-adjusted mortality as an outcome to compare seasonal patterns by month for teaching and non-teaching hospitals.

Results: Of 2,824,694 ischemic stroke discharges, 51.7% were from teaching hospitals. The 30-day RSMR decreased steadily from 1999 to 2006 in teaching hospitals ( Figure 1 A). Seasonal patterns were present within each calendar year, with the highest 30-day RSMR occurring in the winter (January) and the lowest RSMR in the summer, with a secondary peak in July (p=0.004; Figure 1 B). The same patterns were also seen for non-teaching hospitals (not shown).

Conclusions: Thirty-day risk-standardized mortality rates after ischemic stroke in the elderly have decreased between 1999 to 2006. Seasonal patterns are evident, with the highest RSMR in January, and a secondary peak in July. Because these patterns were similar for teaching and non-teaching hospitals, the July peak can not be explained based on the introduction of new trainees. The reasons for these seasonal patterns, including higher mortality rates in July, are unclear.

30-day mortality and readmission after hemorrhagic stroke among Medicare beneficiaries in Joint Commission primary stroke center-certified and noncertified hospitals

BACKGROUND AND PURPOSE

Ischemic stroke patients treated at Joint Commission Primary Stroke Center (JC-PSC)-certified hospitals have better outcomes. Data reflecting the impact of JC-PSC status on outcomes after hemorrhagic stroke are limited. We determined whether 30-day mortality and readmission rates after hemorrhagic stroke differed for patients treated at JC-PSC-certified versus noncertified hospitals.

METHODS

The study included all fee-for-service Medicare beneficiaries aged 65 years or older with a primary discharge diagnosis of subarachnoid hemorrhage (SAH) or intracerebral hemorrhage (ICH) in 2006. Covariate-adjusted logistic and Cox proportional hazards regression assessed the effect of care at a JC-PSC-certified hospital on 30-day mortality and readmission.

RESULTS

There were 2305 SAH and 8708 ICH discharges from JC-PSC-certified hospitals and 3892 SAH and 22 564 ICH discharges from noncertified hospitals. Unadjusted in-hospital mortality (SAH: 27.5% versus 33.2%, P<0.0001; ICH: 27.9% versus 29.6%, P=0.003) and 30-day mortality (SAH: 35.1% versus 44.0%, P<0.0001; ICH: 39.8% versus 42.4%, P<0.0001) were lower in JC-PSC hospitals, but 30-day readmission rates were similar (SAH: 17.0% versus 17.0%, P=0.97; ICH: 16.0% versus 15.5%, P=0.29). Risk-adjusted 30-day mortality was 34% lower (odds ratio, 0.66; 95% confidence interval, 0.58-0.76) after SAH and 14% lower (odds ratio, 0.86; 95% confidence interval, 0.80-0.92) after ICH for patients discharged from JC-PSC-certified hospitals. There was no difference in 30-day risk-adjusted readmission rates for SAH or ICH based on JC-PSC status.

CONCLUSIONS

Patients treated at JC-PSC-certified hospitals had lower risk-adjusted mortality rates for both SAH and ICH but similar 30-day readmission rates as compared with noncertified hospitals.

Abstract P27: Statistical Models of Readmission After Stroke: A Systematic Review

Objective: Hospital readmission has been used to risk-stratify patients and profile hospitals by public reporting of performance measures. We conducted a systematic review to identify models developed to compare hospital rates of readmission or predict patients' risk of readmission after stroke, and identify characteristics independently associated with readmission in these models.

Methods: We identified English-language studies published from 1989-2009 using MEDLINE, PubMed, Scopus, PsychINFO, and all Ovid Evidence-Based Medicine Reviews. Eligible publications reported readmission within 1 year after stroke hospitalization and identified 1 or more predictors of readmission in risk-adjusted statistical models. Publications were excluded if they lacked primary data or quantitative outcomes, considered composite outcomes, or had fewer than 100 patients. Investigators independently reviewed abstracts to select publications that met criteria and used a standardized instrument to perform detailed data abstraction.

Results: Of the 177 publications identified during the initial review, only 9 met the inclusion criteria. None of these papers developed models to compare readmission rates among hospitals or predicted patients' risk of readmission. The studies presented multivariable models that showed specific patient-level and/or process of care factors associated with readmission after stroke. Studies varied in their case definition of stroke, data source (VA, Medicare, administrative data, registries), outcomes (all-cause and/or stroke-related readmission), and follow-up period. There was little consistency of candidate variables across the studies, but more commonly included factors were age (n=8/9), sex (7), race (8), prior stroke (5), hypertension (5), diabetes (6), standardized stroke severity scale (3), other variables related to stroke severity (5), and length of stay (7). Five studies provided significance levels for covariates other than their primary predictor(s); however, few characteristics were consistently associated with readmission.

Conclusions: The lack of risk-standardized models represents an important gap for ongoing efforts to profile hospitals through public reporting of performance measures.

Abstract P26: 30-Day Risk Standardized Mortality and Readmission After Ischemic Stroke by Hospital Minority Volume

Background: Risk-standardized 30-day mortality (RSMR) and readmission (RSRR) rates in part reflect hospital-based and immediate post-discharge care. Differences in rates across hospitals based on the race-ethnic composition of their patient populations may indicate disparities in care. We examined whether hospital 30-day RSMRs and RSRRs after ischemic stroke vary by the proportions of African-Americans (AA) admitted at hospitals in 1994, 2000, and 2006.

Methods: We used Medicare claims data to determine the hospital-level RSMR for any cause 30 days after the index admission and RSRR for any cause within 30 days of discharge among surviving fee-for-service Medicare patients >= 65 years of age discharged with a primary diagnosis of ischemic stroke (ICD-9 433, 434, 436) in 1994, 2000, and 2006. Hierarchical regression models calculated the RSMR and RSRR for hospitals, adjusting for patient demographics and clinical characteristics. Hospitals were grouped into quartiles based on the proportion of AA admitted. Mixed models and quantile regression models examined the relationship between AA volume and outcomes.

Results: The RSMR decreased as the proportion of AA increased, whereas the RSRR increased as the proportion of AA increased (figure). These relationships were consistent within each year, and the variability lessened over time. Quantile regression confirms that the relationship persists across the distribution of RSMR and RSRR.

Conclusions: RSMR and RSRR varied by hospital race-ethnic volume, but differences in outcome lessened over time. Identifying factors contributing to these differences may identify opportunities to improve stroke care among the elderly.

Outcomes after ischemic stroke for hospitals with and without Joint Commission-certified primary stroke centers

BACKGROUND

The Joint Commission (JC) began certifying primary stroke centers (PSCs) in the United States in 2003. We assessed whether 30-day risk-standardized mortality (RSMR) and readmission (RSRR) rates differed between hospitals with and without JC-certified PSCs in 2006.

METHODS

The study cohort included all fee-for-service Medicare beneficiaries ≥65 years old discharged with a primary diagnosis of ischemic stroke (International Classification of Diseases, ninth revision, Clinical Modification 433, 434, 436) in 2006. Hierarchical linear regression models calculated hospital-level RSMRs and RSRRs, adjusting for patient demographics, comorbid conditions, and hospital referral region. Hospitals were categorized as being higher than, no different from, or lower than the national average.

RESULTS

There were 310,381 ischemic stroke discharges from 315 JC-certified PSC and 4,231 noncertified hospitals. Mean overall 30-day RSMR and RSRR were 10.9% ± 1.7% and 12.5% ± 1.4%, respectively. The RSMRs of hospitals with JC-certified PSCs were lower than in noncertified hospitals (10.7% ± 1.7% vs 11.0% ± 1.7%), but the RSRRs were comparable (12.5% ± 1.3% vs 12.4% ± 1.7%). Almost half of JC-certified PSC hospitals had RSMRs lower than the national average compared with 19% of noncertified hospitals, but 13% of JC-certified PSC hospitals had lower RSRRs vs 15% of noncertified hospitals.

CONCLUSIONS

Hospitals with JC-certified PSCs had lower RSMRs compared with noncertified hospitals in 2006; however, differences were small. Readmission rates were similar between the 2 groups. PSC certification generally identified better-performing hospitals for mortality outcomes, but some hospitals with certified PSCs may have high RSMRs and RSRRs whereas some hospitals without PSCs have low rates. Unmeasured factors may contribute to this heterogeneity.

Randomized in situ clinical study comparing the ability of two new desensitizing toothpaste technologies to occlude patent dentin tubules

OBJECTIVE

To compare the ability of two new desensitizing toothpaste technologies (one a 5% NovaMin-based toothpaste and the other an 8% arginine-based toothpaste) to occlude patent dentin tubules in a clinical environment relative to a negative control of water and a control toothpaste after four days of twice-daily brushing and dietary acidic challenges.

METHODS

The study design was a single-center, single-blind, randomized, split-mouth, four-treatment, two-period, crossover, in situ clinical study. Healthy subjects wore two lower intra-oral appliances, retaining four dentin samples for four treatment days for each period of the clinical study. Samples were brushed twice daily with a test product (days 1-4), with an additional acidic challenge introduced on two selective days. Scanning electron microscopy (SEM) images were taken of the dentin surface, and dentinal tubule occlusion assessed using a categorical scale.

RESULTS

The results demonstrated that the 5% NovaMin toothpaste was statistically superior at occluding patent dentin tubules compared to water (p = 0.009) and the control toothpaste (p = 0.02) at day 4. In contrast, the treatment effect resulting from the 8% arginine toothpaste did not demonstrate the same degree of occlusive propensity, showing no significant difference to the water and control toothpaste at the day 4 time point.

CONCLUSION

Application of the 5% NovaMin toothpaste to dentin showed better dentin tubule occlusion and retention abilities in an oral environment under dietary acid challenge conditions, more so than the 8% arginine toothpaste technology. Given modern dietary habits and practices, these results highlight differences in the acid resistance properties of occlusion technologies, and a potential impact on clinical performance.

Use of antithrombotic medications among elderly ischemic stroke patients

BACKGROUND

The use of antithrombotic medications after ischemic stroke is recommended for deep vein thrombosis prophylaxis and secondary stroke prevention. We assessed the rate of receipt of these therapies among eligible ischemic stroke patients age ≥65 years and determined the effects of age and other patient characteristics on treatment.

METHODS AND RESULTS

The analysis included Medicare fee-for-service beneficiaries discharged with ischemic stroke (ICD 433.x1, 434.x1, 436) randomly selected for inclusion in the Medicare Health Care Quality Improvement Program's National Stroke Project 1998 to 1999, 2000 to 2001. Patients discharged from nonacute facilities, transferred, or terminally ill were excluded. Receipt of in-hospital pharmacological deep vein thrombosis prophylaxis, antiplatelet medication, anticoagulants for atrial fibrillation, and antithrombotic medications at discharge were assessed in eligible patients, stratified by age (65 to 74, 75 to 84, and 85+ years). Descriptive models identified characteristics associated with treatment. Among 31 554 patients, 14.9% of those eligible received pharmacological deep vein thrombosis prophylaxis, 83.9% antiplatelet drugs, 82.8% anticoagulants for atrial fibrillation, and 74.2% were discharged on an antithrombotic medication. Rates of treatment decreased with age and were lowest for patients ages 85 years or older. Admission from a skilled nursing facility and functional dependence were associated with lower treatment rates.

CONCLUSIONS

There was substantial underutilization of antithrombotic therapies among elderly ischemic stroke patients, particularly among the very elderly, those admitted from skilled nursing facilities, and patients with functional dependence. The reasons for low use of antithrombotic therapies, including the apparent underutilization of deep vein thrombosis prophylaxis in otherwise eligible patients, require further investigation.

Predictors of hospital readmission after stroke: a systematic review

BACKGROUND AND PURPOSE

Risk-standardized hospital readmission rates are used as publicly reported measures reflecting quality of care. Valid risk-standardized models adjust for differences in patient-level factors across hospitals. We conducted a systematic review of peer-reviewed literature to identify models that compare hospital-level poststroke readmission rates, evaluate patient-level risk scores predicting readmission, or describe patient and process-of-care predictors of readmission after stroke.

METHODS

Relevant studies in English published from January 1989 to July 2010 were identified using MEDLINE, PubMed, Scopus, PsycINFO, and all Ovid Evidence-Based Medicine Reviews. Authors of eligible publications reported readmission within 1 year after stroke hospitalization and identified ≥ 1 predictors of readmission in risk-adjusted statistical models. Publications were excluded if they lacked primary data or quantitative outcomes, reported only composite outcomes, or had < 100 patients.

RESULTS

Of 374 identified publications, 16 met the inclusion criteria for this review. No model was specifically designed to compare risk-adjusted readmission rates at the hospital level or calculate scores predicting a patient's risk of readmission. The studies providing multivariable models of patient-level and/or process-of-care factors associated with readmission varied in stroke definitions, data sources, outcomes (all-cause and/or stroke-related readmission), durations of follow-up, and model covariates. Few characteristics were consistently associated with readmission.

CONCLUSIONS

This review identified no risk-standardized models for comparing hospital readmission performance or predicting readmission risk after stroke. Patient-level and system-level factors associated with readmission were inconsistent across studies. The current literature provides little guidance for the development of risk-standardized models suitable for the public reporting of hospital-level stroke readmission performance.

Postendarterectomy mortality in octogenarians and nonagenarians in the USA from 1993 to 1999

BACKGROUND

Relatively little is known about trends in the utilization or outcomes of carotid endarterectomy (CEA) in the very elderly. We determined trends in the rates of CEA and perioperative (in-hospital and 30-day) and long-term (1-, 2-, 3-, 4- and 5-year) mortality in a US national sample of patients >or=80 years of age.

METHODS

All fee-for-service Medicare patients (80-89 and >or=90 years of age) who had a CEA [ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification): 38.12] from 1993 to 1999 were identified using the Centers for Medicare and Medicaid Services Inpatient Standard Analytic Files. Demographic characteristics and comorbid conditions were determined using ICD-9-CM diagnostic codes within the year prior to the index hospitalization for CEA.

RESULTS

A total of 140,376 CEA were performed in patients aged 80-89 years and 6,446 in those aged >or=90 years during this 7-year period. The annual number of operations increased from 13,115 in 1993 to 21,582 in 1999 for octogenarians, and from 481 in 1993 to 1,257 in 1999 for nonagenarians. Perioperative mortality was 2.2% in octogenarians and 3.3% in nonagenarians. Long-term mortality increased by approximately 10% per year after the operation, and was 43% in octogenarians and 56% in nonagenarians at 5 years. Perioperative mortality rates remained relatively stable over the 7-year period for both age groups although comorbidities increased.

CONCLUSIONS

The number of CEA performed in the very elderly in the USA increased from 1993 to 1999. Perioperative mortality rates were high compared with trial results, while long-term survivorship was comparable to that of similarly-aged peers in the USA.

Stroke patient outcomes in US hospitals before the start of the Joint Commission Primary Stroke Center certification program

BACKGROUND AND PURPOSE

The Joint Commission (JC) began certifying Primary Stroke Centers in November 2003. Cross-sectional studies assessing the impact of certification could be biased if these centers had better outcomes before the start of the program. We determined whether hospitals certified within the first years of the JC program had better outcomes than noncertified hospitals before the start of the certification program.

METHODS

The study sample included Medicare fee-for-service beneficiaries >or=65 years of age discharged with ischemic stroke in 2002 from 5070 hospitals, 317 of which were JC-certified by June 2007. Hierarchical logistic regression and Cox proportional hazards models were used to compare in-hospital mortality, 30-day mortality, and 30-day readmission for patients treated at future JC-certified versus noncertified hospitals.

RESULTS

Among 366 551 patients, 18% (66 300) were treated at hospitals with centers that were JC-certified within the first few years of the program. These patients were younger, more likely to be white and male, and had fewer comorbidities and hospitalizations within the prior year. Unadjusted in-hospital mortality (4.7% versus 5.5%), 30-day mortality (9.8% versus 11.3%), and readmissions (13.8% versus 14.6%) were lower in the future JC-certified hospitals (all P<0.001). These differences remained after risk adjustment (in-hospital mortality: OR, 0.93; 95% CI, 0.90 to 0.96; 30-day mortality: OR, 0.92; 95% CI, 0.87 to 0.96; 30-day readmission: hazard ratio, 0.97; 95% CI, 0.95 to 0.99).

CONCLUSIONS

JC Primary Stroke Center-certified hospitals had better outcomes than noncertified hospitals even before the program began. Cross-sectional studies assessing the effects of stroke center certification need to account for these pre-existing differences.

Elderly women have lower rates of stroke, cardiovascular events, and mortality after hospitalization for transient ischemic attack

BACKGROUND AND PURPOSE

Patients with transient ischemic attack (TIA) are at increased risk for stroke, cardiovascular events, and death, yet little is known about whether these risks differ for men and women. We determined whether there are sex-based differences in these outcomes 30 days and 1 year after TIA using a national sample of elderly patients.

METHODS

Rates of 30-day and 1-year hospitalization for TIA (International Classification of Diseases, 9th Revision Code 435), stroke (International Classification of Diseases, 9th Revision Codes 433, 434, and 436), coronary artery disease (International Classification of Diseases, 9th Revision Codes 410 to 414), all-cause readmission, and mortality were determined for fee-for-service Medicare patients >or=65 years of age discharged with a TIA in 2002. Cox proportional hazards models and random-effects logistic models compared outcomes with risk adjustment for demographics, medical history, comorbidities, and prior hospitalizations.

RESULTS

The study included 122063 TIA hospitalizations (mean age, 79.0+/-7.6 years; 62% women; 86% white). Men were younger but had higher rates of cardiac comorbidities than women. Women had lower unadjusted rates of stroke, coronary artery disease, and mortality at 30 days and 1 year after TIA admission. These relationships persisted in risk-adjusted analyses at 30 days for stroke (hazard ratio, 0.70; 95% CI, 0.64 to 0.77), coronary artery disease (hazard ratio, 0.86; 0.74 to 1.00), and mortality (odds ratio, 0.74; 0.68 to 0.82) as well as at 1 year for stroke (hazard ratio, 0.85; 0.81 to 0.89), coronary artery disease (hazard ratio, 0.81; 0.77 to 0.86), and mortality (odds ratio, 0.78; 0.75 to 0.81).

CONCLUSIONS

These data suggest that women have a better prognosis than men within the first year after hospital discharge for a TIA. Additional research is needed to identify factors that may explain these sex-related differences in outcomes.

Anesthesia in ambulatory minimally invasive surgery

The increasing popularity of minimally invasive surgery has grown concurrently with the demand for ambulatory surgery. Standard outpatient procedures such as tubal ligation are now being joined by ambulatory laparoscopic cholecystectomy. In order for ambulatory minimally invasive surgery to succeed, patient selection must be appropriate, careful attention paid to the physiologic changes of pneumoperitoneum, and pain and nausea treated pre-emptively.

Glutamate-induced delta-catenin redistribution and dissociation from postsynaptic receptor complexes

Delta-catenin (or neural plakophilin-related arm-repeat protein/neurojungin) is primarily a brain specific member of the p120(ctn) subfamily of armadillo/beta-catenin proteins that play important roles in neuronal development. Our previous studies have shown that the ectopic expression of delta-catenin induces the formation of dendrite-like extensions and that the overexpression of delta-catenin promotes dendritic branching and increases spine density. Here we demonstrate that delta-catenin displays a dendritic distribution pattern in the adult mouse brain and is co-enriched with postsynaptic density-95 (PSD-95) in the detergent insoluble postsynaptic scaffolds. Delta-catenin forms stable complexes with excitatory neurotransmitter receptors including ionotropic N-methyl-D-aspartic acid receptor 2A (NR2A), metabotropic glutamate receptor 1alpha (mGluR1alpha), as well as PSD-95 in vivo. In cultured primary embryonic neurons, delta-catenin clusters co-distribute with filamentous actin and resist detergent extraction. In dissociated hippocampal neurons overexpressing delta-catenin, glutamate stimulation leads to a rapid redistribution of delta-catenin that can be attenuated by 6-cyano-7-nitroquinoxaline-2,3-dione and dizocilpine, selective inhibitors of ionotropic glutamate receptors. Upon glutamate receptor activation, delta-catenin becomes down-regulated and its association with NR2A and mGluR1alpha in cultured neurons is diminished. These findings support a possible functional connection between delta-catenin and the glutamatergic excitatory synaptic signaling pathway during neuronal development.

Cholinergic and behavioral neurotoxicity of carbaryl and cadmium to larval rainbow trout (Oncorhynchus mykiss)

Pesticides and heavy metals are common environmental contaminants that can cause neurotoxicity to aquatic organisms, impairing reproduction and survival. Neurotoxic effects of cadmium and carbaryl exposures were estimated in larval rainbow trout (RBT; Oncorhynchus mykiss) using changes in physiological endpoints and correlations with behavioral responses. Following exposures, RBT were videotaped to assess swimming speed. Brain tissue was used to measure cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number, and MChR affinity. ChE activity decreased with increasing concentrations of carbaryl but not of cadmium. MChR were not affected by exposure to either carbaryl or cadmium. Swimming speed correlated with ChE activity in carbaryl-exposed RBT, but no correlation occurred in cadmium-exposed fish. Thus, carbaryl exposure resulted in neurotoxicity reflected by changes in physiological and behavioral parameters measured, while cadmium exposure did not. Correlations between behavior and physiology provide a useful assessment of neurotoxicity.

Medullary osteogenesis with platinum cathodes

Studies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose-response relationship between current and bone growth. Examination of the effect of differing geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport "distributive" cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current-bone growth dose-response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 microA (versus 20 microA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable material for chronic indwelling anodes for stimulation of osteogenesis.

Surgical aspects and future developments of laparoscopy

Laparoscopy has revolutionized surgery and in the process influenced the practice of anesthesiology. This article reviews several minimal access procedures that have been accepted into practice, are gaining acceptance, or remain investigational. Absolute contraindications to laparoscopy have been emphasized. As the threshold for primary care physicians to refer sicker and sicker patients for surgery decreases, it is crucial for the anesthesiologist to understand physiologic stresses of pneumoperitoneum and the nuances of laparoscopic surgery. The anesthesiologist also can be recruited to adjust insufflation pressures, tweak images on monitors, rotate and position the patient, or pass balloons and bougies. With patient and surgeon expectation of no pain or nausea and early discharge, anesthetic choices become vital for the ultimate success of the procedure.

Norepinephrine modulates myelopoiesis after experimental thermal injury with sepsis

OBJECTIVE

To determine whether thermal injury and sepsis cause an increase in bone marrow norepinephrine release and whether such a release influences bone marrow monocytopoiesis.

SUMMARY BACKGROUND DATA

The authors previously demonstrated enhanced bone marrow monocytopoiesis after burn with sepsis. They also showed that physiologic stress and bacterial challenge without injury could lead to a dynamic release of norepinephrine from the bone marrow compartment. In this study, they sought to determine the potential cause-and-effect relationship of bone marrow norepinephrine release on increased monocytopoiesis after burn sepsis.

METHODS

Norepinephrine release from bone marrow was determined by traditional pulse-chase methods. Tissue and bone marrow norepinephrine content was ablated by chemical sympathectomy with 6-hydroxydopamine treatment. Clonogenic potential in response to colony-stimulating factors was determined in total nucleated bone marrow cells. Dual color flow cytometry was used to document the distribution pattern of monocyte progenitors.

RESULTS

Burn sepsis induced increased norepinephrine release in bone marrow, spleen, and heart. Colony-forming assays demonstrated an increase in responsive colonies, which was significantly attenuated when norepinephrine content was reduced in animals before burn sepsis. Flow cytometric analysis of early and late monocyte progenitors showed a significantly altered distribution profile of monocyte progenitors in norepinephrine-depleted mice compared with norepinephrine-intact mice. Abrogation of bone marrow norepinephrine content resulted in a 62% survival rate in burn septic mice compared with no survivors in norepinephrine-intact mice.

CONCLUSIONS

These data suggest that enhanced bone marrow norepinephrine release after burn sepsis may play a role in bone marrow monocytopoiesis, thus contributing to the sustenance of inflammation.

Behavioral dysfunctions correlate to altered physiology in rainbow trout (Oncorynchus mykiss) exposed to cholinesterase-inhibiting chemicals

We selected four metrics of swimming behavior (distance swam, speed, rate of turning, and tortuosity of path) and the commonly used biochemical marker, brain cholinesterase (ChE) activity, to assess (1) the sensitivity and reliability of behavior as a potential biomarker in monitoring work, (2) the potential for these endpoints to be used in automated monitoring, and (3) the linkage between behavior and its underlying biochemistry. Malathion-exposed fish exhibited large decreases in distance and speed and swam in a more linear path than control fish after 24 h exposure. By 96 h exposure, fish still swam slower and traveled less distance; fish fully recovered after 48 h in clean water. Diazinon-exposed fish exhibited decreases in distance, speed, and turning rate compared to controls. After 48 h recovery in clean water, fish exposed to diazinon had not recovered to control levels. The behavioral responses provided measures of neurotoxicity that were easily quantifiable by automated means, implying that the inclusion of behavior in monitoring programs can be successful. Furthermore, correlations between behavior and biochemical endpoints, such as ChE inhibition, suggest that this approach can provide a meaningful link between biochemistry and behavior and can provide useful information on toxicant impacts.

Microgravity effects on water supply and substrate properties in porous matrix root support systems

The control of water content and water movement in granular substrate-based plant root systems in microgravity is a complex problem. Improper water and oxygen delivery to plant roots has delayed studies of the effects of microgravity on plant development and the use of plants in physical and mental life support systems. Our international effort (USA, Russia and Bulgaria) has upgraded the plant growth facilities on the Mir Orbital Station (OS) and used them to study the full life cycle of plants. The Bulgarian-Russian-developed Svet Space Greenhouse (SG) system was upgraded on the Mir OS in 1996. The US developed Gas Exchange Measurement System (GEMS) greatly extends the range of environmental parameters monitored. The Svet-GEMS complex was used to grow a fully developed wheat crop during 1996. The growth rate and development of these plants compared well with earth grown plants indicating that the root zone water and oxygen stresses that have limited plant development in previous long-duration experiments have been overcome. However, management of the root environment during this experiment involved several significant changes in control settings as the relationship between the water delivery system, water status sensors, and the substrate changed during the growth cycles.

Preparing surgeons for the 21st century. Implications of advanced technologies

An entire spectrum of advanced technologies and concepts has been presented, from the new clinical applications to highly speculative possibilities. Not all of these technologies will survive the long process to clinical usefulness, but those that do may revolutionize surgery. With such change comes the ethical and moral responsibility to consider them not only in the light of improvement of patient care but also in their impact on society as a whole. If the remarkable rate of change of the past 2 decades continues, it is impossible to conceive of the role of future surgeons. Thus, to be prepared, surgeons must have an open mind, a willingness to consider and evaluate new directions, and the honesty and courage to change when a new approach is proven to be of value. A prepared mind is an open mind.

An approach for assessment of water quality using semipermeable membrane devices (SPMDs) and bioindicator tests

As an integral part of our continued development of water quality assessment approaches, we combined integrative sampling, instrumental analysis of widely occurring anthropogenic contaminants, and the application of a suite of bioindicator tests as a specific part of a broader survey of ecological conditions, species diversity, and habitat quality in the Santa Cruz River in Arizona, USA. Lipid-containing semipermeable membrane devices (SPMDs) were employed to sequester waterborne hydrophobic chemicals. Instrumental analysis and a suite of bioindicator tests were used to determine the presence and potential toxicological relevance of mixtures of bioavailable chemicals in two major water sources of the Santa Cruz River. The SPMDs were deployed at two sites; the effluent weir of the International Wastewater Treatment Plant (IWWTP) and the Nogales Wash. Both of these systems empty into the Santa Cruz River and the IWWTP effluent is a potential source of water for a constructed wetland complex. Analysis of the SPMD sample extracts revealed the presence of organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The bioindicator tests demonstrated increased liver enzyme activity, perturbation of neurotransmitter systems and potential endocrine disrupting effects (vitellogenin induction) in fish exposed to the extracts. With increasing global demands on limited water resources, the approach described herein provides an assessment paradigm applicable to determining the quality of water in a broad range of aquatic systems.

Controversies in sentinel lymph node biopsy for breast cancer

Sentinel lymph node biopsy, validated in melanoma staging, is currently under investigation for breast cancer staging. Reports suggest that the sentinel lymph node has a high predictive value in determining the presence of axillary metastases. Identification of a sentinel lymph node that is free of metastatic tumor cells may eliminate the necessity of performing a standard axillary lymph node dissection with its attendant morbidity. Numerous techniques are utilized to identify the sentinel node with approximately the same success rate. This paper will address some of the controversial areas of sentinel lymph node biopsy and offer an option for physicians who want to develop a sentinel lymph node program in their hospital.