Health Factors Associated With Development and Severity of Poststroke Dysphagia: An Epidemiological Investigation

BACKGROUND

Dysphagia after stroke is common and can impact morbidity and death. The purpose of this population-based study was to determine specific epidemiological and health risk factors that impact development of dysphagia after acute stroke.

METHODS AND RESULTS

Ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review from the GCNKSS (Greater Cincinnati Northern Kentucky Stroke Study), a representative sample of ≈1.3 million adults from southwestern Ohio and northern Kentucky. Dysphagia status was determined on the basis of clinical assessments and necessity for alternative access to nutrition via nasogastric or percutaneous endoscopic gastrostomy tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and premorbid conditions. Multivariable logistic regression determined factors associated with increased risk of dysphagia. Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed that increased age, Black race, higher National Institutes of Health Stroke Scale score at admission, having a hemorrhagic stroke (versus infarct), and right hemispheric stroke increased the risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower prestroke modified Rankin Scale score, and white matter disease.

CONCLUSIONS

This study replicated previous findings of variables associated with dysphagia (older age, worse stroke, right-sided hemorrhagic lesions), whereas other variables identified were without clear biological rationale (eg, Black race, history of high cholesterol, and presence of white matter disease) and should be investigated in future studies to determine biological relevance and potential influence in stroke recovery.

Health factors associated with development and severity of post-stroke dysphagia: an epidemiological investigation

Background and Purpose

Dysphagia is a common post-stroke occurrence and has been shown to impact patients' morbidity and mortality. The purpose of this study was to use a large population-based dataset to determine specific epidemiological and patient health risk factors that impact development and severity of dysphagia after acute stroke.

Methods

Using data from the Greater Cincinnati Northern Kentucky Stroke Study, GCNKSS, involving a representative sample of approximately 1.3 million people from Southwest Ohio and Northern Kentucky of adults (age ≥18), ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review. Dysphagia status was determined based on bedside and clinical assessments, and severity by necessity for alternative access to nutrition via nasogastric (NG) or percutaneous endoscopic gastrostomy (PEG) tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and pre-morbid conditions. Multivariable logistic regression was used to determine factors associated with increased risk of developing dysphagia.

Results

Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed: increased age, Black race, higher NIHSS score at admission, having a hemorrhagic stroke (vs infarct), and right hemispheric stroke increased risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower pre-stroke mRS score, and white matter disease.

Conclusions

This study replicated many previous findings of variables associated with dysphagia (older age, worse stroke, right sided hemorrhagic lesions), while other variables identified were without clear biological rationale (e.g. Black race, history of high cholesterol and presence of white matter disease). These factors should be investigated in future, prospective studies to determine biological relevance and potential influence in stroke recovery.

Abstract WMP5: How Do Clinical Trial Exclusion Criteria Impact The Inclusivity Of Clinical Trials?

Intro: Enrolling women and under-represented minorities into clinical trials is a top priority for the stroke community. Common trial exclusions for medical conditions or demographics may negatively impact enrollment for these groups. We sought to describe the potential impact that various exclusion criteria have on trial eligibility of ischemic stroke (IS) patients by race and sex within the large, biracial Greater Cincinnati/Northern Kentucky Stroke Study (GCNKSS) population.

Methods: The GCNKSS is a population-based study of 1.3 million people living in a 5-county area of southern Ohio/ Northern Kentucky. During 7/1/14-12/31/15 for blacks, and 2015 for whites, we captured all hospitalized ischemic strokes by screening ICD-9 codes 430-436 and ICD10 codes I60-I68, and G45-46. Commonly used exclusion criteria from stroke clinical trials were applied to the GCNKSS IS population, and were compared by sex and race. All comparisons were evaluated with chi-square test and corrected for multiple comparisons, as necessary.

Results: In 2014-2015, there were 2806 ischemic stroke patients, which were 53% female, and 30% black. Table 1 presents common clinical trial exclusion criteria and the % excluded among IS patients, stratified by sex and race. Every trial exclusion evaluated had significant differences by sex, race, or both.

Discussion: Within our population, we found that commonly-used age and disability clinical trial exclusion criteria exclude more women than men, and exclusion of milder strokes affects more men than women. Blood pressure, renal function, and early arrival time criteria exclude more blacks than whites, while older age exclude more whites than blacks. Optimal clinical trial design should be informed by epidemiology data to ensure representation of underrepresented populations in clinical trials. We will continue to provide epidemiology feedback on acute trial exclusion criteria to NIH StrokeNet proposals in the future.

Abstract WP125: Relationships Of Hemoglobin With Ischemic Lesions After Intracerebral Hemorrhage

Introduction: Hemoglobin concentrations and diffusion weighted imaging (DWI) lesions are separately known to be associated with poor intracerebral hemorrhage (ICH) outcomes. Though hemoglobin concentrations are related to both hypoxia and thrombosis at their extremes, it is unknown whether hemoglobin concentrations relate to DWI lesions after ICH.

Methods: Spontaneous, supratentorial ICH patients with available baseline hemoglobin and hospitalized MRI data enrolled into a multicenter cohort study between 2010-2016 were analyzed. Baseline hemoglobin was assessed as both a continuous variable (g/dL) and categorical variable (<11, 11 to <13, 13 to <15, >/=15 g/dL). Primary analyses assessed relationships of baseline hemoglobin with MRI DWI lesions. Secondary analyses assessed independent relationships of hemoglobin and DWI lesions with poor 3-month outcomes (modified Rankin Scale [mRS] 4-6). Separate multivariable regression models assessed these relationships after adjusting for relevant covariates.

Results: Of 917 ICH patients analyzed, the mean baseline hemoglobin was 13.8 g/dL (+/-1.9), 60% were deep ICH, and DWI lesions were identified in 27% of the cohort. In our primary analyses, increased hemoglobin, defined as a continuous variable, was associated with DWI lesions (adjusted OR 1.21, 95% CI: 1.07-1.37) after adjusting for sex, race, ICH severity, time to MRI, and blood pressure treatment change. In secondary analyses, DWI lesions were associated with poor 3-month outcomes (adjusted OR 1.83, 95% CI: 1.24-2.69) adjusting for similar covariates. We identified associations of low hemoglobin categories, when referenced to hemoglobin 13 to <15 g/dL, with poor outcomes (<11 g/dL: adjusted OR 1.99, 95% CI: 1.05-3.79; 11 to <13 g/dL: adjusted OR 1.62, 95% CI: 1.04-2.52). Effect estimates of high hemoglobin (>/=15 g/dL) with poor outcomes were smaller and imprecise (adjusted OR 1.39, 95% CI: 0.89-2.17).

Conclusions: We identified novel relationships between higher baseline hemoglobin concentrations and DWI lesions in ICH patients. Further studies are required to clarify the role of hemoglobin concentrations on both cerebral small vessel disease pathophysiology and ICH outcomes.

Racial Disparities in Stroke Recurrence: A Population-Based Study

BACKGROUND

There are significant racial disparities in stroke in the United States, with Black individuals having a higher risk of incident stroke even when adjusted for traditional stroke risk factors. It is unknown whether Black individuals are also at a higher risk of recurrent stroke.

METHODS

Over an 18-month period spanning 2014-2015, we ascertained index stroke cases within the Greater Cincinnati/Northern Kentucky population of 1.3 million. We then followed all patients for 3 years and determined the risk of recurrence. Multivariable survival analysis was performed to determine the effect of Black race on recurrence.

RESULTS

There were 3816 patients with index stroke/TIA events in our study period, and 476 patients had a recurrent event within three years. The Kaplan-Meier estimate of 3-year recurrence rate was 15.4%. Age- and sex-adjusted stroke recurrence rate was higher in Black individuals (HR 1.34, 95% CI 1.1-1.6; p=0.003); however, when adjusted for traditional stroke risk factors including hypertension, diabetes, smoking status, age, and left ventricular hypertrophy, the association between Black race and recurrence was significantly attenuated and became nonsignificant (HR 1.1, 95% CI 0.9-1.36, p=0.32). At younger ages, Black race was more strongly associated with recurrence and this effect may not be fully attenuated by traditional stroke risk factors.

CONCLUSIONS

Recurrent stroke was more common among Black individuals, but the magnitude of the racial difference was substantially attenuated and became nonsignificant when adjusted for traditional stroke risk factors. Interventions targeting these risk factors could reduce disparities in stroke recurrence.

Abstract 93: Utility Of Routine Inpatient Echocardiography In Acute Ischemic Stroke Patients With Established Stroke Etiology: A Population Study

Background: Acute ischemic stroke (AIS) remains a leading cause of mortality and disability worldwide, with stroke etiology having an important role in work-up, management, and prognosis. The current AHA/ASA guidelines cite routine echocardiography as reasonable but not mandatory for the work-up of ischemic stroke. We sought to identify how often transthoracic echocardiogram (TTE) results would show a potentially treatment-altering finding.

Methods: Using the Greater Cincinnati/Northern Kentucky Stroke Study (GCNKSS) for years 2005, 2010, and 2015, we selected patients with a new diagnosis of AIS using ICD-9/10 codes in adults ≥18yrs of age presenting to the emergency department and who had a TTE with stroke etiology of Cardioembolic, Small Vessel, or Large Vessel. All cases were physician reviewed and stroke etiology determined based on our epidemiologic criteria. Demographic information, medical history, electrocardiograms with atrial fibrillation (Afib), and TTE features were collected for each patient and compared across stroke etiology groups using Wilcoxon rank sum test and chi-square test, or Fisher’s exact test, as appropriate.

Results: There were 5,490 patients presenting with AIS in the GCNKSS in 2005, 2010, and 2015 and 3,984 (73%) had a TTE performed. Of those with TTE, 2,422 (61%) had a presumed etiology of Small Vessel, Large Artery Atherosclerosis (LAA), or Cardioembolic (120 identified as “Other,” 1442 identified as “Undetermined”). Potential findings of TTE that could change management were 1% in Small Vessel, 2% in LAA, and 7% in Cardioembolic etiology strokes.

Conclusion: In patients presenting with Small Vessel or LAA stroke etiologies, routine inpatient TTE rarely had management-changing findings. Future studies are needed in order to assess cost effective use of TTE in patients with established stroke etiology.

Abstract TP137: Ethnic/racial Variations Of Intracerebral Hemorrhage Genetics (erich-gene) Study Protocol

Introduction: Epidemiologic studies of intracerebral hemorrhage (ICH) have consistently demonstrated variation in incidence, location, comorbidity burden, age-of-onset, and outcome by race and ethnicity, and genetic studies have identified differences in risk mediated by genetic risk factors such as Apolipoprotein E (APOE). We report the design and methods of the largest multi-ethnic genome-wide association study (GWAS) of ICH risk and outcome conducted to date.

Methods: The Ethnic/Racial Variations of ICH Genetics (ERICH-GENE) study is an international, multi-center, genetic case-control study of ICH. Cases are individuals with confirmed primary ICH with biosample availability and consent compatible with shareable genome-wide genotyping or previous genotyping. Central neuroimaging phenotype harmonization of case status, hemorrhage location, and imaging characteristics of cerebral small vessel disease including leukoaraiosis, atrophy, microbleeds, intraventricular hemorrhage severity and volume of ICH measurements will be performed. Controls are ICH-free individuals of compatible age and race/ethnicity from existing studies and biorepositories.

Results: As of August 2021, 2,002 ICH cases have been collected and genotyped, in addition to 2,558 already-genotyped ICH cases from the multi-ethnic ERICH study. 5,600 total new ICH cases will be genotyped under ERICH-GENE, with planned meta-analyses across existing ICH GWAS datasets and international biobanks totaling >20,000 cases. We are on schedule to meet our genotyping goal within the study period. Non-European ancestry cases are being prioritized for genotyping and ~66% of the previously genotyped ERICH cases are black or Hispanic. From available cases, a total of 10,621 neuroimaging studies have been uploaded for central adjudication to date with 6,278 having undergone harmonization.

Conclusions: ERICH-GENE is a large, multi-ethnic, international, centrally harmonized GWAS of ICH risk and outcome that will identify genetic risk factors across diverse populations for biological discovery and population-specific risk stratification.

Abstract WP7: Critical Importance Of Enrollment Hours For Successful Recruitment In Acute Stroke Trials

Introduction: Recruitment into hyperacute stroke trials is challenging but ultimately depends on on-call availability of treating investigators, study coordinators, and pharmacists. These data may not be considered in initial decision-making for site selection and estimates of site recruitment are frequently based upon registry data from sites that includes all clinical cases.

Hypothesis: Site recruitment on a per month basis is associated with time open for enrollment.

Methods: We surveyed all Multi-arm Optimization of Stroke (MOST) trial centers open for enrollment to determine which were open for trial recruitment during business hours during Monday through Friday only, business hours 7 days a week, extended hours beyond business hours, or 24 hours/7 days a week. We also surveyed about pharmacy availability. Descriptive statistics were used to compare the average monthly enrollment by survey responses.

Results: Sites open for enrollment only during business hours, Monday through Friday recruited at a rate of 0.14 participants per month compared to 0.36 per month for sites that enroll 7 days a week (see graphic). Restriction of pharmacy availability to business hours Monday through Friday was associated with decreased recruitment rate as well.

Conclusions: Ability to recruit trial participants 7 days a week should be the standard for site selection, successful acute stroke trial recruitment, and estimates of needed sites. Methods to increase financial support for hours outside of week-day business hours is a potential method to enhance recruitment into acute stroke trials.

Abstract WP206: Temporal Trends In Stroke Patients Who Had Prior Transient Ischemic Attack And Did Not Present To The Emergency Room: A Population Study

Background: Acute ischemic stroke (AIS) is a leading cause of disability worldwide, with up to 30% of cases preceded by transient ischemic attack (TIA). Urgent evaluation of TIA symptoms is recommended to reduce risk of stroke, but not all patients with TIA symptoms seek evaluation. Our goal was to assess temporal trends in the demographics of such patients.

Methods: Using the Greater Cincinnati/Northern Kentucky Stroke Study (GCNKSS) for years 2005, 2010, and 2015, we selected patients with a diagnosis of AIS using ICD-9/10 codes in adults ≥18yrs of age presenting to the ED. We identified patients who had a preceding TIA based on symptoms within 60 days of presentation, as judged by an adjudicating physician. Demographics, histories, and proportion of patients with TIA were compared across study years using Wilcoxon rank sum test or chi-square test.

Results: We identified 5977 patients presenting with AIS across three epochs. Of these 207 (3%) had prior suspected TIA and did not seek immediate medical attention; 56/1790 (3%) in 2005, 62/1993 (3%) in 2010, and 70/2194 (3%) in 2015 (p-value=0.99). Patients with suspected TIA had increasing rates of previously diagnosed HLD and DM over the three time periods. No other risk factors or demographics showed a change over time. Known HTN was consistently prevalent across epochs (Table 2).

Conclusion: Over the three epochs, 3% of AIS patients consistently did not seek emergent medical attention for a recent preceding TIA. A substantial proportion of these patients were increasingly already diagnosed with DM and HLD over the study periods, and the majority were persistently diagnosed with HTN. This is an opportune cohort for future targeted outreach.

Abstract WP177: Trends In The Clinical Phenotype Of Infective Endocarditis Related Stroke From 2005-2015: A Population-Based Study Of The Greater Cincinnati/ Northern Kentucky Region

Background: Prior studies have demonstrated a rising incidence of infective endocarditis related stroke (IERS) in the US due to the opioid epidemic. The Greater Cincinnati/Northern Kentucky (GCNK) region has one of the highest opioid abuse rates in the nation. A modern epidemiologic description is necessary to understand the impact of the opioid epidemic on the clinical phenotype of IERS.

Methods: Using the GCNK Stroke Study, all patients hospitalized with IERS in 2005, 2010, and 2015 were abstracted and physician reviewed. IERS was defined as an acute stroke clinically attributed to infective endocarditis in patients meeting modified Duke Criteria for possible or definite endocarditis. Comparison between years were by chi-square or Fisher’s exact test for categorical variables; ANOVA or Kruskal-Wallis test for numerical variables. Cochran-Armitage test was used to examine trend. Secondary analysis compared characteristics between intravenous drug users (IVDU) and non-IVDU.

Results: A total of 54 patients with IERS were identified in 2005, 2010, and 2015. Over the period, there was a significant decline in hypertension (91.7% in 2005, 36.0% in 2015; p=0.0005) and increase in IVDU (8.3% in 2005, 44.0% in 2015; p=0.02). They trended towards increased white race, younger age, and fewer vascular risk factors. Compared to non-IVDU, IVDU were significantly younger (41.1±14.1vs 63.1±14.3 years; p<0.001), less often female (12.5% vs 47.4%; p=0.02), had higher rates of sepsis (50% vs 18.4%; p=0.04), less atrial fibrillation (0% vs 31.6%; p=0.01), and less renal disease (0% vs 23.7%; p=0.045). The incidence of IERS per 100,000 increased from 1.31 (CI: 0.56-2.06) in 2005, to 1.66 (CI: 0.87-2.45) in 2010, and to 2.41(CI:1.46-3.36) in 2015.

Conclusion: From 2005 to 2015, IERS was increasingly associated with IVDU and an absence of hypertension. These trends likely reflect the demographics of the opioid epidemic, which has affected younger patients with less comorbidities.

Contribution of Racial and Ethnic Differences in Cerebral Small Vessel Disease Subtype and Burden to Risk of Cerebral Hemorrhage Recurrence

OBJECTIVE

Black and Hispanic survivors of intracerebral hemorrhage (ICH) are at higher risk of recurrent intracranial bleeding. MRI-based markers of chronic cerebral small vessel disease (CSVD) are consistently associated with recurrent ICH. We therefore sought to investigate whether racial/ethnic differences in MRI-defined CSVD subtype and severity contribute to disparities in ICH recurrence risk.

METHODS

We analyzed data from the Massachusetts General Hospital ICH study (n = 593) and the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study (n = 329). Using CSVD markers derived from MRIs obtained within 90 days of index ICH, we classified ICH cases as cerebral amyloid angiopathy (CAA)-related, hypertensive arteriopathy (HTNA)-related, and mixed etiology. We quantified CSVD burden using validated global, CAA-specific, and HTNA-specific scores. We compared CSVD subtype and severity among White, Black, and Hispanic ICH survivors and investigated its association with ICH recurrence risk.

RESULTS

We analyzed data for 922 ICH survivors (655 White, 130 Black, 137 Hispanic). Minority ICH survivors had greater global CSVD (p = 0.011) and HTNA burden (p = 0.021) on MRI. Furthermore, minority survivors of HTNA-related and mixed-etiology ICH demonstrated higher HTNA burden, resulting in increased ICH recurrence risk (all p < 0.05).

CONCLUSIONS

We uncovered significant differences in CSVD subtypes and severity among White and minority survivors of primary ICH, with direct implication for known disparities in ICH recurrence risk. Future studies of racial/ethnic disparities in ICH outcomes will benefit from including detailed MRI-based assessment of CSVD subtypes and severity and investigating social determinants of health.

Genome-wide association study of cerebral small vessel disease reveals established and novel loci

Intracerebral haemorrhage and small vessel ischaemic stroke (SVS) are the most acute manifestations of cerebral small vessel disease, with no established preventive approaches beyond hypertension management. Combined genome-wide association study (GWAS) of these two correlated diseases may improve statistical power to detect novel genetic factors for cerebral small vessel disease, elucidating underlying disease mechanisms that may form the basis for future treatments. Because intracerebral haemorrhage location is an adequate surrogate for distinct histopathological variants of cerebral small vessel disease (lobar for cerebral amyloid angiopathy and non-lobar for arteriolosclerosis), we performed GWAS of intracerebral haemorrhage by location in 1813 subjects (755 lobar and 1005 non-lobar) and 1711 stroke-free control subjects. Intracerebral haemorrhage GWAS results by location were meta-analysed with GWAS results for SVS from MEGASTROKE, using 'Multi-Trait Analysis of GWAS' (MTAG) to integrate summary data across traits and generate combined effect estimates. After combining intracerebral haemorrhage and SVS datasets, our sample size included 241 024 participants (6255 intracerebral haemorrhage or SVS cases and 233 058 control subjects). Genome-wide significant associations were observed for non-lobar intracerebral haemorrhage enhanced by SVS with rs2758605 [MTAG P-value (P) = 2.6 × 10-8] at 1q22; rs72932727 (P = 1.7 × 10-8) at 2q33; and rs9515201 (P = 5.3 × 10-10) at 13q34. In the GTEx gene expression library, rs2758605 (1q22), rs72932727 (2q33) and rs9515201 (13q34) are significant cis-eQTLs for PMF1 (P = 1 × 10-4 in tibial nerve), NBEAL1, FAM117B and CARF (P < 2.1 × 10-7 in arteries) and COL4A2 and COL4A1 (P < 0.01 in brain putamen), respectively. Leveraging S-PrediXcan for gene-based association testing with the predicted expression models in tissues related with nerve, artery, and non-lobar brain, we found that experiment-wide significant (P < 8.5 × 10-7) associations at three genes at 2q33 including NBEAL1, FAM117B and WDR12 and genome-wide significant associations at two genes including ICA1L at 2q33 and ZCCHC14 at 16q24. Brain cell-type specific expression profiling libraries reveal that SEMA4A, SLC25A44 and PMF1 at 1q22 and COL4A1 and COL4A2 at 13q34 were mainly expressed in endothelial cells, while the genes at 2q33 (FAM117B, CARF and NBEAL1) were expressed in various cell types including astrocytes, oligodendrocytes and neurons. Our cross-phenotype genetic study of intracerebral haemorrhage and SVS demonstrates novel genome-wide associations for non-lobar intracerebral haemorrhage at 2q33 and 13q34. Our replication of the 1q22 locus previous seen in traditional GWAS of intracerebral haemorrhage, as well as the rediscovery of 13q34, which had previously been reported in candidate gene studies with other cerebral small vessel disease-related traits strengthens the credibility of applying this novel genome-wide approach across intracerebral haemorrhage and SVS.

Abstract WMP51: Ischemic Stroke Rates in Those With Diabetes in the Black and White Population: An Update

Background: We previously reported an increased incidence of stroke in the population with diabetes. This was particularly pronounced in those under 65 years of age. With guidelines now including glycemic monitoring during hospitalization, we examined incidence attributable to diabetes in 2010 and 2015.

Methods: Ischemic strokes in the 5-county Greater Cincinnati/Northern Kentucky region were ascertained, then physician verified, at all 15 area hospitals using ICD-9 codes 430 to 436 or ICD10 codes I60 to I68. First ever ischemic strokes in patients aged 20 years and older were included in this analysis. Population age-specific rates of diabetes were estimated using the 2009-2010 and 2015-2016 NHANES databases, then applied to local population numbers, extracted from the US Census Bureau website, to estimate the denominator for calculation of incidence rates. Incidence rates were adjusted by age race and sex, as appropriate, to the 2010 US population. Diabetes was defined as reported in the electronic medical record or glycohemoglobin A1c &gt 6.4% during hospitalization.

Results: There were a total of 4141 ischemic strokes; 55% female and 22% black. Stroke rates continue to be substantially higher in those with diagnosed diabetes, than those without diabetes overall and for those less than 65 years in both time periods, as well as those 65 years and older except for the black population in 2010. Racial disparities continue in both the less than 65 and 65 years and older age groups. Stroke rates were higher for Blacks in the less than 65 year age group for those both with and without diabetes; with risk ratios ranging from 1.3 to 2.7. Of note the stroke rate has decreased between 2010 and 2015 for those with diabetes <65 years of age. (Table)

Conclusions: The population with diabetes continues to be at increased risk of stroke, especially in those less than 65 years of age and those of black race.

Abstract WP265: Racial Differences in Left Atrial Size Among Patients With Ischemic Stroke

Introduction: Blacks in the U.S. face twice the risk of ischemic stroke as whites, and this disparity is not fully explained by established stroke risk factors. Although atrial fibrillation (AF) is a major risk factor for stroke, blacks are less often diagnosed with AF than whites. It is unclear whether this paradox exists because AF is less thoroughly ascertained in blacks compared to whites or because blacks have less predisposing substrate and thus a truly lower risk of AF.

Hypothesis: Based on our prior work, we hypothesized that black patients with ischemic stroke less often have left atrial enlargement, a major predisposing factor for AF.

Methods: We compared left atrial size in black versus white patients in the Greater Cincinnati/Northern Kentucky Stroke Study, a study of racial disparities in stroke incidence in a nationally representative population of 1.3 million. We obtained reports of echocardiograms performed for stroke evaluation among patients in the 2010 and 2015 study periods. Patients with known AF or atrial flutter were excluded. Investigators blinded to patients’ characteristics abstracted left atrial diameter from echocardiogram reports. Linear regression was used to examine the association between race and left atrial diameter after adjustment for demographics, body mass index, and comorbidities.

Results: Among 2,980 cases of ischemic stroke without AF, the median age was 66 years, 52% were female, and 30% were black. The overall mean left atrial diameter was 3.65 (±0.69) cm. Despite a higher burden of vascular risk factors and comorbidities, blacks had significantly smaller left atrial diameters (mean difference, -0.10 cm; 95% CI, -0.04 to -0.17 cm). This difference persisted after adjustment for demographics, comorbidities, and body mass index (adjusted mean difference, -0.15 cm; 95% CI, -0.09 to -0.21 cm).

Conclusions: In a population-based sample, we found that black patients with ischemic stroke had smaller left atrial size than white patients. Our results suggest that the paradox of greater stroke risk but lower AF risk in blacks compared with whites at least partly stems from a lesser degree of AF substrate in blacks.

Abstract WMP54: Updated Population Trends in Substance Abuse Preceding Stroke in Young Adults: 1993/1994 to 2015

Objective: To update trends on documented substance abuse among young adults (18-54 years old) with stroke within the Greater Cincinnati/Northern Kentucky Stroke Study population, to include preliminary results from 2015.

Background: Substance abuse is associated with stroke. In our population, we previously reported increases in overall substance abuse, smoking history, and use of alcohol or drugs <24 hours prior to stroke onset. We also found increased illicit drug use in the 35 to 54 age group from 1993/94 through 2010. We now report trends after adding 2015 preliminary results.

>Design/Methods: Using ICD-9 discharge codes 430-436, potential acute stroke events are identified among 18- to 55-year-old residents of the 5 county study region. Five one-year study periods are included (7/93-6/94, 1999, 2005, 2010, 2015). Study nurses abstract all events which then undergo physician review. We searched for trends in smoking history, illicit drug use, heavy alcohol consumption, overall substance abuse (current smoking, alcohol, and illicit drug), and urine/blood test positive for alcohol or illicit drugs at presentation.

Results: There were 2220 stroke events (75 % ischemic). Sex and age distribution remained stable; however, percent black increased from 35% to 46% between 1993/94 and 2015, as did the proportion of ischemic strokes (74% to 77%). Current smoking and alcohol use remained stable while illicit drug use increased significantly overall and within the age subgroups of 18-34 years and 35-54 years (see table).

Conclusions: Illicit drug use continues to increase among young adults with stroke. Even though the possibility of testing bias needs to be explored further, our reported results are likely an under estimation of true rates as there are no readily available tests for new designer drugs which have become more available since the early 2000’s. Future analysis will also focus on the relationship between our findings and the U.S. opioid epidemic.

Abstract TMP57: Racial Disparities in Recurrent Stroke Rates: Preliminary Results From the Greater Cincinnati/Northern Kentucky Population in 2015

Introduction: The REGARDS study previously reported a lack of racial disparity in recurrent ischemic stroke (IS) events, despite large racial differences in incident IS. We sought to evaluate recurrent stroke rates at 1 year after an index ischemic (IS) or hemorrhagic (ICH and SAH) stroke or TIA within a large, biracial population representative of the US in terms of % blacks and sociodemographics with a large number of index events

Methods: The Greater Cincinnati/Northern Kentucky Stroke Study ascertained all hospitalized strokes and TIAs among residents of a 5-county population of 1.3 million in 7/1/14-12/31/14 (blacks only) and 2015 (all residents), as well as recurrent strokes (but not TIAs) in 2016. One year risk of recurrent stroke was estimated by Kaplan-Meier analysis. Association between recurrent stroke and demographics/risk factors was assessed by proportional hazards analysis.

Results: Among the 2014-15 cases, there were 3883 index events (2512 IS, 374 ICH, 92 SAH, 900 TIA, 5 unknown type). Median age was 70 (IQR 59, 81); 27% were black and 54% female. Recurrent events within 12 months of the index event occurred in 319 patients (276 IS, 38 ICH, 5 SAH). Those with recurrence were more likely black than those without (34% vs 27%, p<0.01). No differences between those with recurrence and those without was seen for age at index event (median 70 vs 70, p=0.33) or sex (female 56% vs 54%, p=0.44). One-year risk of recurrent stroke was 9.3% overall (11.3% black, 8.6% white); 10.0% after index IS, 11.2% for ICH/SAH, 7.2% after TIA. Hazard ratio for risk of recurrent stroke for blacks compared with whites, adjusted for age and sex, was 1.38 (95% CI 1.09, 1.75).

Discussion: The risk of recurrent stroke was significantly associated with index event type and stroke risk factors (hypertension, diabetes, smoking, and prior stroke). Black race was not a significant independent predictor of recurrent stroke after adjusting for other known stroke risk factors.

Abstract TMP58: Preliminary Population-Based Temporal Trends in Stroke Incidence: Racial Disparity and Stroke Incidence From 1993-2015

Introduction: We previously reported that the incidence of stroke was decreasing for whites but stable for blacks from 1993/94 to 2005. We sought to describe recent temporal trends and racial disparities in stroke incidence within our large, bi-racial population, by including 2010 and preliminary data from 2015.

Methods: The Greater Cincinnati/Northern Kentucky region includes two southern Ohio and three Northern Kentucky counties on the Ohio River, a population of 1.3 million representative of the US population in terms of sociodemographics and percent black race. Our study ascertained all hospitalized strokes that occurred in the population between 7/1/93 and 6/30/94 and in calendar years 1999, 2005, 2010 and 2015. For 2015, nursing review of medical records is complete but physician review is not; thus 2015 rates are preliminary. The denominator for the calculation of incidence rates (in those aged ≥20 years) was estimated from the U.S. Census Bureau website (www.census.gov). The 95% confidence intervals (CI) for the incidence rates were calculated assuming a Poisson distribution. Rates are age, sex, and race adjusted, as appropriate, and standardized to the 2010 U.S. population.

Results: First-ever stroke incidence rates stratified by subtype, race, and study period are presented in the Table. We project that stroke incidence did not significantly change in 2015 vs. 2010 for either blacks or whites, regardless of stroke subtype. Blacks have a substantially higher incidence of stroke compared with whites in all study periods, without significant change in disparity over time.

Discussion: In contrast to the significant decline in stroke incidence among whites from 1993-94 to 2005, we did not observe a statistically significant decrease in 2010 and 2015. This may be due to true stabilization of rates over time, or less statistical power to detect smaller declines. The substantial black/white racial disparity in stroke incidence has not changed over time.

Abstract WMP32: Adaptive and Maladaptive Remodeling in Flow Loaded Rat Cerebral Arteries: Potential Significance to Pathogenesis of Cerebral Aneurysms

Background and purpose: In animal models, flow loading is a necessary and sufficient hemodynamic factor to express the cerebral aneurysm (CA) phenotype. Promotional biological factors may include variant forms of the adaptive response to flow loading. Using a rat model, this study characterizes molecular events that comprise cerebral arterial responses to flow loading and reveals their significance in relation to the CA phenotype.

Methods: 32 rats underwent bilateral common carotid artery ligation (BCL) (n=16) or sham surgery (SS)(n=16). Nineteen days later, vertebrobasilar arteries were harvested, histologically examined and analyzed for mRNA and protein expression. Flow (shear) induced changes in mRNA expression, protein expression and histology were determined by comparing BCL to SS rats. Differences between aneurysm-prone (Long Evans, LE) and resistant (Brown Norway, BN) strains were evaluated.

Results: Basilar artery medial thickness/luminal diameter ratio was significantly reduced in BCL rats, without significant differences between LE (2.02 fold) and BN (1.94 fold) rats. BCL significantly altered basilar artery expression of mRNA and proteins that modulate wall structure and function but had no effect on blood pressure. Eight genes showed similarly large flow induced expression changes in LE and BN rats (TyrRS, Mfge8, Galnt13, GABRP, Pp1r1a, Dpt_predicted, Cd34_predicted, ApoE). Twenty six shear responsive genes showed significant differences in shear induced expression between LE and BN rats. The Cthrc1, Gsta3, Tgfb3, Ldha, Myo1d, Ermn, PTHrp, Rgs16 and TRCCP genes showed the strongest shear responsive expression, and the largest difference in shear responsive expression between LE and BN rats.

Conclusions: Our study reveals specific molecular biological responses involved in flow induced expansive remodeling of cerebral arteries. A group of 9 strongly shear responsive genes showed major differences in flow induced expression between LE and BN rats and are implicated as having important roles in maladaptive remodeling associated with the CA phenotype.

Abstract 211: Do Women Receive Less Aggressive Care Following Intracerebral Hemorrhage?

Background: Several studies have shown that women with ischemic stroke receive fewer proven therapies for secondary prevention. A small study found that women receive early DNR orders after intracerebral hemorrhage (ICH) more often than men ( Stroke 2013; 44: 3229) but national data regarding sex differences in ICH are lacking.

Objective: To compare comorbidities and use of surgical treatments and palliative care between men and women with ICH. We tested the hypothesis that women receive less aggressive care after ICH.

Methods: ERICH is a multi-center study of ICH risk factors and outcomes. We compared clinical variables, treatments (e.g., hematoma evacuation), and use of DNR orders in men compared with women. Chi square tests(categorical items) and t-tests (continuous items) were performed. Multivariable analyses assessed the likelihood of ICH surgery and/or palliative care after adjustment for variables that were significant (p<.05) in univariate analyses.

Results: 2964 patients (1220 women) were analyzed. Mean age was higher in women (65.0 vs. 59.9, p<.0001). There was no sex difference in hypertension frequency but women had a higher proportion of previous stroke (24.1% vs. 19.3%, p=.002), dementia (6.1% vs. 3.4%, p=.0007), and anticoagulant use (12.8% vs. 10.1%, p=.02). Men had a higher proportion of cocaine use (10.1% vs. 4.7%, p<.0001) and higher initial SBP (187.5 mm vs. 183.5 mm, p=.007). A higher proportion of women reported living alone (23.1% vs. 18.0%, p=.0005) and a higher proportion of women had a lobar ICH (36.9% vs. 27.4%, p<.0001). After adjustment for age, dementia, prior stroke, anticoagulant use, and ICH location, there was no difference in surgical treatment between men and women (OR=0.92, 95%CI=0.67-1.26, p=.59). Although a higher proportion of women were made DNR/comfort care (19.4% vs. 15.3%, p=.003), this finding was no longer significant after adjustment for ICH score, prior stroke, and dementia (OR for male sex=.96, 95%CI=0.77-1.22, p=.76).

Conclusions: Despite sex differences in several categories, no observable sex differences were found in use of surgical therapies or use of DNR/comfort care in an American population. Future work should focus on whether sex differences exist following ICH in patient-centered outcomes.

Combined Approach to Lysis Utilizing Eptifibatide and Recombinant Tissue-Type Plasminogen Activator in Acute Ischemic Stroke-Full Dose Regimen Stroke Trial

BACKGROUND AND PURPOSE

The Combined Approach to Lysis Utilizing Eptifibatide and Recombinant Tissue-Type Plasminogen Activator (r-tPA; CLEAR) in Acute Ischemic Stroke (AIS) and CLEAR-Enhanced Regimen (CLEAR-ER) trials demonstrated safety of reduced dose r-tPA plus the glycoprotein 2b/3a inhibitor, eptifibatide, in AIS compared with r-tPA alone. The objective of the CLEAR-Full Dose Regimen (CLEAR-FDR) trial was to estimate the rate of symptomatic intracerebral hemorrhage (sICH) in AIS patients treated with the combination of full-dose r-tPA plus eptifibatide.

METHODS

CLEAR-FDR was a single-arm, prospective, open-label, multisite study. Patients aged 18 to 85 years treated with 0.9 mg/kg IV r-tPA within 3 hours of symptom onset were enrolled. After obtaining consent, eptifibatide (135 μg/kg bolus and 2-hour infusion at 0.75 μg/kg per minute) was administered. The primary end point was the proportion of patients who experienced sICH within 36 hours. An independent clinical monitor adjudicated if an sICH had occurred and an independent neuroradiologist reviewed all images. The stopping rule was 3 sICHs within the first 19 patients or 4 sICHs within 29 patients.

RESULTS

From October 2013 to December 2014, 27 patients with AIS were enrolled. Median age was 73 years (range, 34-85; interquartile range, 65-80) and median National Institute of Health stroke scale score was 12 (range, 6-26; interquartile range, 9-16). One sICH (3.7%; 95% confidence interval, 0.7%-18%) was observed.

CONCLUSIONS

These results demonstrate comparable safety of full-dose r-tPA plus eptifibatide with historical rates of sICH with r-tPA alone and support proceeding with a phase 3 trial evaluating full-dose r-tPA combined with eptifibatide to improve outcomes after AIS.

Abstract W P23: Predictors of Time From Groin Puncture to Base Catheter Placement

Background and Purpose: Time to reperfusion is recognized as an important predictor of good outcome in endovascular stroke therapy. A significant but unstudied factor in delay to reperfusion is prolonged time from groin puncture to base catheter placement (P2C). The purpose of this study was to assess the factors that influence time from P2C in the cohort of patients in whom procedural steps were collected prospectively.

Methods: A prospective analysis of patients who had intra-arterial therapy for acute stroke from August of 2012 to August of 2013 was performed. Following characteristics were collected: baseline clinical demographics, aortic arch types, time from P2C, procedural and clinical outcomes.

Results: Data from a total of 143 patients were collected prospectively {median age 69 years; median baseline NIH Stroke Scale 16; occlusion sites: MCA-M1 71%; MCA-M2 13%, ICA-T 6%, basilar artery 10%, tandem occlusion 26%}. Patients were further divided based on their arch type (type 1: 48%, type 2: 33%, type 3: 13%). Majority of the patients were treated with newer mechanical embolectomy devices (manual aspiration +/- stent-retriever 96%). Recanalization rate (TICI 2b or 3) was 90%. The median procedural times were as follow (minutes): time from P2C: 20, time from baseline catheter to reperfusion: 36, median total procedural times: 85. The rate of favorable functional outcomes at 90 days (mRS 0-2) was 45%. Patients with favorable outcomes had shorter P2C (31 min vs. 19 min p=0.02). In a multivariate analysis the predictors of longer P2C were age (OR 1.04, P=0.05, 95% CI 1.00-1.08), vertebrobasilar location (OR 5.4, P=0.027, 95% CI 1.21-24.1), smoking (OR 3.7, P=0.02, 95% 1.2-11.1), and with trend toward significance for hypertension (OR 3.03, P=0.062, 95% 0.94-0.97).

Discussion: Shorter P2C is associated with higher rate of favorable outcomes. Independent risk factors associated longer time are age, vertebrobasilar occlusions, active smoking and history of hypertension. Alternative arterial access may be considered in patients who are likely to have longer P2C.

Abstract WP18: Gender Differences In Intra-arterial Therapy

Background: Women have higher post-stroke mortality and rate of disability. Earlier studies have reported on difference between outcomes in men and women with regard to CEA, stenting and tPA. However, there are no studies comparing gender differences with intra-arterial (IA) treatment in patients with symptomatic intracranial stenosis.

Methods: This retrospective study performed at an academic tertiary care facility compared men and women treated for M1 severe stenosis or occlusion with IA therapy from November 2002 to May 2011. We compared baseline premorbid conditions. Treatment outcomes included infarct size, modified Rankin Scale (mRS) and mortality. Two-tailed Fischer’s Exact Test was used for data analysis.

Results: Of 223 patients, 105 (47.1%) were men and 113 (50.7%) were women. Women were older (64.1 vs. 67.9 years; p < 0.05). Baseline characteristics such as hypertension, atrial fibrillation and hyperlipidemia showed no significant differences between men and women (p> 0.05). NIHSS at presentation (15.5 vs 16.1; p > 0.05) and infarct size post intervention (78.6 vs 76.5 cc 3 ; p > 0.05) were not different. Successful revascularization rate was 88% in women and 81% in men (p = 0.15). 56% of men but only 41% of women had a mRS ≤ 2 at 3 months. (p < 0.05). Preliminary data suggests no differences in mortality.

Conclusion: Despite the findings that infarct size and revascularization rates were the same between men and women, women had worse functional outcomes at 3 months. In future investigations, we will identify contributing factors that may explain outcome differences between men and women.

Abstract 3531: Clinical Outcomes Following Endovascular Stroke Treatment Facilitated via Telestroke Evaluation

BACKGROUND: Most stroke patients present to small community hospitals without established stroke pathways or interventional stroke treatment capability. The advent of 2 way audiovisual telestroke systems gives such patients the opportunity to be assessed rapidly by stroke neurologists. Patients who are not candidates for systemic IV tPA or have failed thrombolytic treatment can be identified and transferred to a comprehensive stroke center for potential endovascular treatment. We compared the clinical outcomes of patients undergoing endovascular stroke treatment at University of Pittsburgh Medical Center triaged either through telestroke or non-telestroke means.

METHODS: Prospective data including demographics, co-morbidities, baseline Alberta Stroke Program Early CT (ASPECT) and National Institute of Health Stroke Scale (NIHSS) score, intervention modality (pharmacological, mechanical or both), time to treatment, clinical outcome, and hemorrhage and mortality rates were compared. Favorable outcome was defined as modified rankin score (mRS) of 2 or less.

RESULTS: Between 3/2007 and 5/2011, thirty four patients underwent endovascular stroke treatment following telestroke evaluation versus 354 patients who were triaged through other means. Baseline characteristics were similar between the groups. Time to endovascular treatment (595 vs. 767 minutes; p = 0.5), pretreatment with systemic tPA (51.6 vs. 56.9%, p=0.6), recanalization (TIMI ≥ 2; 91.2% vs. 84.8%; p = 0.31), favorable outcome (modified rankin score ≤ 2; 50% vs. 40.4%; p = 0.29) and mortality rates (28.1% vs. 34.9%, p=0.44) were comparable. Multivariate logistic regression model identified young age (OR 0.91, CI 0.88-0.95, p<0.01), successful recanalization (OR 3.3, CI 1.8-6.2, p<0.01), and baseline ASPECT score (OR 6.5, CI 2.4-17.4, p<0.01) as predictors of favorable outcome.

CONCLUSION: The results of this study suggest that telestroke guided endovascular stroke treatment is feasible and the outcomes are similar to those patients who were triaged by traditional means. Future randomized studies which specifically compare triage via telemedicine vs. telephone or direct emergency department presentation are needed to substantiate these findings.

DNA-ploidy, G2M-fractions and prognosis of stages B and C prostate carcinoma

Paraffin embedded tissue of 49 stage C and 27 stage B prostate adenocarcinomas was investigated by flow cytometry. All patients were treated by radical prostatectomy with pelvic lymphadenectomy and followed up for 5-10 years. The tumour was separated from the benign tissue to increase the proportion of tumour cells. Ten stage C and seven stage B carcinomas had to be excluded because of poor fixation. Six of the 39 (15%) stage C and 1/20 (5%) stage B carcinomas were aneuploid. Cell cycle analysis was done with correction for sliced nuclei and background subtraction. The threshold between carcinomas with low and with increased ("tetraploid") G2M-fraction was determined by comparing carcinomas with and without tumour progression. Sixty-seven percent of the patients with non-euploid stage C carcinomas and 11% of those with euploid carcinomas suffered from tumour progression (P < 0.01). The respective values for the stage B carcinomas were 67% and 6% (P < 0.01). These results demonstrate the strong prognostic impact of DNA-ploidy and G2M-fractions for each individual patient.

[Chemical and microbiological studies of microwave-treated milk]

Pasteurized milk was treated with microwaves for 2.5 minutes (2450 MHz, 650 W). Important chemical components (vitamin A, beta-carotin, vitamins B1, B2, C, E; activity of peroxidase, xanthinoxidase; content of fat and peroxides, percentage of solids, content of raw protein, content of all microorganisms and storage stability were examined. Ascorbic acid (reduction of 36%) and alpha-tocopherol (reduction of 17%) were influenced by microwave treatment, whereas other chemical parameters, odor and flavor remained unchanged. The content of microorganisms was reduced from about 10(4) to 10(2) per milliliter. Untreated milk had a content of 10(7) microorganisms per milliliter after 10 days storage at 8 degrees C and a taste of acidity, whereas in milk treated with microwaves only 10(4) microorganisms per ml were identified and no organoleptic changes could be observed after 14 days storage at 8 degrees C.

Pathological alterations in human tendons

The present authors analyzed the pathological alterations of 1966 tendons examined in the National Institute of Traumatology, Budapest, during the past 18 years. The majority of cases proved to be tendinopathies (hypoxic-degenerative tendinopathy or calcific tendinitis, tendolipomatosis and mucoid degeneration) leading to tendon rupture. The incidence of tendon tumors, foreign bodies, infectious tendon diseases, and other pathological conditions was clearly lower. The methods of tissue preparation and of examination of tendon specimens were also evaluated. Light microscopy was sufficient for the diagnosis of pyogenic tendinitis, tumors, xanthoma, gout, and gangrene. In degenerative tendinopathies and alterations due to hereditary disease, electron microscopy was necessary. Polarization microscopy had a key role in examination of collagen structure and architecture, and identification of foreign bodies in the tendons. Enzyme histochemical and immunohistochemical examination were reliable but not absolutely necessary in the diagnosis of tendon pathology.

Fibronectin and laminin in Achilles tendon

Ten intact and 22 ruptured Achilles tendons were studied by immunohistochemical techniques. In intact tendons, both fibronectin and laminin were found in vascular walls, myotendineal junction, and endomysium, but not in the connective tissue of the tendons. In ruptured tendons the distribution of laminin was not changed. Fibronectin deposits, on the contrary, could be detected on the tear surface and in the collagen fibers of the ruptured tendons.

Foreign bodies in tendons

At the National Institute of Traumatology in Budapest, a search has been made for foreign bodies in tendons over the last 15 years. 53 foreign bodies have been found in 931 tendons removed at operation and 45 foreign bodies in 950 tendon samples at autopsy. The foreign material was found to be organic in 29 cases, metal in 20 cases and plastic in six cases. In the others, glass, sand, mineral grease and textiles could be detected. In 33 cases the material could not be identified. The foreign bodies were found in the tendons of the upper extremities in 51 cases and the lower extremities in 47 cases. Foreign bodies in the tendons were more likely to cause problems in the upper limbs than in the lower limbs: these problems were purulent tendonitis, necrosis, foreign body granuloma, fibrosis and peritendonitis and calcification.

Immunopathological study on palmar aponeurosis in Dupuytren's disease

The authors examined the immunological and immunohistochemical alterations of palmar aponeurosis in Dupuytren's contracture. In the IgG-content no difference were found between the intact and diseased aponeurosis. The mean of IgA content was 2 fold, the IgM content 3 fold higher in Dupuytren's aponeurosis than in normal ones. The immunoglobulin containing cells localised around the Dupuytren's nodules and in fibrotic, but not nodular parts of aponeurosis. Extracellular immunoglobulin deposits were not found.

Ultrahistochemical localization of the glutamate-oxaloacetate transaminase (GOT) enzyme in hepatic and skeletal muscle cells in rat

The ultrastructural localization of the glutamate-oxaloacetate transaminase (GOT) enzyme in hepatic and skeletal muscle cells has been studied. The GOT activity localized first on the cristae of mitochondria both in hepatic and skeletal muscle cells. Further activity of the enzyme was observed in the endoplasmic reticulum and in sarcoplasmic reticulum but not in other cell components.

Ultrastructural changes in human liver cells due to reversible acute hypoxia

The ultrastructural alterations in human liver cells have been studied in reversible acute hypoxia. After thoracic and/or craniocerebral injury, the arterial oxygen saturation was under 60 mm Hg, and the circulation was intact, in all 20 patients. The hepatic cells were characterized by depletion of glycogen, swelling of the mitochondria with some irregularity of their membranes, and swelling of the endoplasmic reticulum, as well as by the appearance of large hypoxic vacuoles.

Alterations of oxygen and carbon dioxide tensions in crush-injured calf muscles of rat

The alterations of oxygen and carbon dioxide tensions in crush-injured muscles were determined by means of a Silastic-tonometer. Immediately after crush-injury the oxygen tension was elevated, then declined and 2 hours after trauma a value of 10 to 14 mmHg was reached. The oxygen tension was 8 to 15 mmHg the next four days after injury, from 5th day the tissue pO2 elevated rapidly. On 14th day the tissue oxygen tension was 60-72 mmHg, thereafter decreased gradually to 40-50 mmHg by the 19th day. The tissue pCO2 elevated within 2 hours after injury to 95-105 mmHg. From 5th day decreased gradually to 50 mmHg by the 21st day.

Oxygen and carbon dioxide tensions in calf muscles of rat

The oxygen and carbon dioxide tension were studies with Silastic tonometer technique in skeletal muscle and subcutaneous tissue of rat. The high initial pO2 was caused by airborne contamination during implantation and declined rapidly. Tissue gas tensions measured with a Silastic tonometer reflect the healing sequences of implantation trauma and stable readings are not obtained until 14 days after implantation. After healing of implantation injury 42 to 47 mmHg pO2 and 50 to 57 mmHg pCO2 were measured in muscle and 23 to 26 mmHg pO2 and 51 to 57 mmHg pCO2 in subcutaneous tissue of rat.

Histochemical and ultrastructural study of human muscles after spontaneous rupture of the tendon

The authors studied the histochemical and ultrastructural alterations of human muscles after spontaneous rupture of the tendon. Both succinate dehydrogenase (in type 1 fibres), and ATPase (in type 2 fibres) activity decreased in all injured muscles. In the intact antagonists and in contralateral muscles alterations were not found. The creatine phosphokinase and aldolase activity were decreased also in the injured muscles. The lactate dehydrogenase activity was various both in affected and in unaffected antagonists muscles. 2 weeks or more after the rupture of the tendon, in the injured muscles the number of type 1 fibres were decreased and therefore a statistically significant type 2 fibre predominance occurred. Ultrastructurally the disruption and disorientation of the myofibrils, streaming and disorganisation of Z line were found. The sarcolemma was arranged, the sarcoplasmic reticulum was dilated; both normal, pycnotic and enlarged mitochondria were observed. The motor end-plates were not discernible.