Discontinuation of Alzheimer Disease Medications in Patients Receiving Home Care Medicine.

There is no consensus on how long antidementia medications should be administered to patients with Alzheimer disease (AD). To clarify this issue, we investigated the discontinuation of antidementia medications in Japanese home care settings, including community-dwelling and institutionalized patients. Using medical records from April 2017 to March 2022 at 3 clinics in Tokyo and Chiba prefectures, we selected patients with AD who started receiving home care medicine. Forty-nine patients discontinued antidementia medications during the observation period, there was no apparent deterioration in cognitive function or new occurrence of behavioral and psychological symptoms of dementia caused by the discontinuation of medications. More aggressive discontinuation of AD medications probably is recommended for patients with activities of daily living dysfunction, such as those receiving home care medicine.

Regulatory T Cells in Melanoma Revisited by a Computational Clustering of FOXP3+ T Cell Subpopulations.

CD4(+) T cells that express the transcription factor FOXP3 (FOXP3(+) T cells) are commonly regarded as immunosuppressive regulatory T cells (Tregs). FOXP3(+) T cells are reported to be increased in tumor-bearing patients or animals and are considered to suppress antitumor immunity, but the evidence is often contradictory. In addition, accumulating evidence indicates that FOXP3 is induced by antigenic stimulation and that some non-Treg FOXP3(+) T cells, especially memory-phenotype FOXP3(low) cells, produce proinflammatory cytokines. Accordingly, the subclassification of FOXP3(+) T cells is fundamental for revealing the significance of FOXP3(+) T cells in tumor immunity, but the arbitrariness and complexity of manual gating have complicated the issue. In this article, we report a computational method to automatically identify and classify FOXP3(+) T cells into subsets using clustering algorithms. By analyzing flow cytometric data of melanoma patients, the proposed method showed that the FOXP3(+) subpopulation that had relatively high FOXP3, CD45RO, and CD25 expressions was increased in melanoma patients, whereas manual gating did not produce significant results on the FOXP3(+) subpopulations. Interestingly, the computationally identified FOXP3(+) subpopulation included not only classical FOXP3(high) Tregs, but also memory-phenotype FOXP3(low) cells by manual gating. Furthermore, the proposed method successfully analyzed an independent data set, showing that the same FOXP3(+) subpopulation was increased in melanoma patients, validating the method. Collectively, the proposed method successfully captured an important feature of melanoma without relying on the existing criteria of FOXP3(+) T cells, revealing a hidden association between the T cell profile and melanoma, and providing new insights into FOXP3(+) T cells and Tregs.

CD8⁺ tumor-infiltrating lymphocytes at primary sites as a possible prognostic factor of cutaneous angiosarcoma.

Tumor-infiltrating lymphocytes (TILs) have been reported as a prognostic factor in various cancers and are a promising target for immunotherapy. To investigate whether TILs have any impact on the prognosis of angiosarcoma patients, 55 non-treated patients (40 patients at stage 1 with cutaneous localized tumors, 4 patients at stage 2 with lymph node metastases and 11 patients at stage 3 with distant metastases) with angiosarcoma were evaluated retrospectively by immunohistochemistry stained CD4, CD8, FOXP3 and Ki67. The Kaplan-Meier method was used to estimate overall survival with patients at stage 1. Survival differences were analyzed by the log-rank test. Patients with higher numbers of CD8(+) TILs in their primary tumors survived significantly longer compared with patients with lower values. Moreover, the number of CD8 in TILs was positively correlated with a distant metastasis-free period. The total number of primary TILs (CD4 plus CD8) and CD8(+) primary TILs of stage 3 patients with distant metastases was positively correlated with their overall survival. To evaluate whether CD8(+) effector T cells are activated or differentiated, flow cytometric analysis of peripheral blood mononuclear cells (PBMC) was performed. The percentages of CD8(+) T cells producing IFN-γ in PBMC were significantly higher in patients with angiosarcoma (n = 10) compared not only with that of healthy controls (n = 20) but also patients with advanced melanoma (n = 11). These results suggest that anti-tumor immunity is clinically relevant in angiosarcoma.

Dronedarone and Captisol-enabled amiodarone in an experimental cardiac arrest.

OBJECTIVE: To compare the energy required for defibrillation and postshock outcomes after the administration of dronedarone, amiodarone, and placebo in a porcine model of cardiac arrest. METHODS: Forty-two pigs were randomized to amiodarone, dronedarone, or control treatments. After induction of ventricular fibrillation, compressions and ventilations were performed for 3 minutes and treatment was administered over 30 seconds. If defibrillation was unsuccessful, cardiopulmonary resuscitation continued and repeated shocks were administered every 2 minutes with continual hemodynamic monitoring for a total duration of 30 minutes. RESULTS: The cumulative energy required for defibrillation was 570 ± 422 J for dronedarone, 441 ± 365 J for amiodarone, and 347 ± 281 J for control (P = not significant). Survival at 30 minutes was 1 (7.1%) for dronedarone compared with 11 (78.6%) for control (P = 0.001). Mortality in the dronedarone group was because of refibrillation in 3 (21.4%) cases, atrioventricular block in 1 (7.1%) case, and hypotension not because of bradycardia in 9 (64.3%) cases. Two minutes after successful defibrillation, systolic aortic pressure was lower in dronedarone versus control (86.6 ± 26.9 vs. 110 ± 15.1 mm Hg; P = 0.035). CONCLUSIONS: The administration of dronedarone resulted in a significant reduction in survival and both systolic aortic and coronary perfusion pressure compared with control.

Treatment with a highly selective ß1 antagonist causes dose-dependent impairment of cerebral perfusion after hemodilution in rats.

BACKGROUND: Acute ß-blockade has been associated with a dose-dependent increase in adverse outcomes, including stroke and mortality. Acute blood loss contributes to the incidence of these adverse events. In an attempt to link the risks of acute blood loss and ß-blockade, animal studies have demonstrated that acute ß-blockade impairs cerebral perfusion after hemodilution. We expanded on these findings by testing the hypothesis that acute ß-blockade with a highly ß(1)-specific antagonist (nebivolol) causes dose-dependent cerebral hypoxia during hemodilution. METHODS: Anesthetized rats and mice were randomized to receive vehicle or nebivolol (1.25 or 2.5 mg/kg) IV before hemodilution to a hemoglobin concentration near 60 g/L. Drug levels, heart rate (HR), cardiac output (CO), regional cerebral blood flow (rCBF, laser Doppler), and microvascular brain Po(2) (P(Br)O(2), G2 Oxyphor) were measured before and after hemodilution. Endothelial nitric oxide synthase (NOS), neuronal NOS (nNOS), inducible NOS, and hypoxia inducible factor (HIF)-1α were assessed by Western blot. HIF-α expression was also assessed using an HIF-(ODD)-luciferase mouse model. Data were analyzed using analysis of variance with significance assigned at P < 0.05, and corrected P values are reported for all post hoc analyses. RESULTS: Nebivolol treatment resulted in dose-specific plasma drug levels. In vehicle-treated rats, hemodilution increased CO and rCBF (P < 0.010) whereas P(Br)O(2) decreased to 45.8 ± 18.7 mm Hg (corrected P < 0.001; 95% CI 29.4-69.7). Both nebivolol doses comparably reduced HR and attenuated the CO response to hemodilution (P < 0.012). Low-dose nebivolol did not impair rCBF or further reduce P(Br)O(2) after hemodilution. High-dose nebivolol attenuated the rCBF response to hemodilution and caused a further reduction in P(Br)O(2) to 28.4 ± 9.6 mm Hg (corrected P = 0.019; 95% CI 17.4-42.7). Both nebivolol doses increased brain endothelial NOS protein levels. Brain HIF-1α, inducible NOS, and nNOS protein levels and brain HIF-luciferase activity were increased in the high-dose nebivolol group after hemodilution (P < 0.032). CONCLUSIONS: Our data demonstrate that nebivolol resulted in a dose-dependent decrease in cerebral oxygen delivery after hemodilution as reflected by a decrease in brain tissue Po(2) and an increase in hypoxic protein responses (HIF-1α and nNOS). Low-dose nebivolol treatment did not result in worsened tissue hypoxia after hemodilution, despite comparable effects on HR and CO. These data support the hypothesis that acute ß-blockade with a highly ß(1)-specific antagonist causes a dose-dependent impairment in cerebral perfusion during hemodilution.

Clinical benefit of switching from paclitaxel to docetaxel or vice versa in cutaneous angiosarcoma patients resistant to first taxane chemotherapy.

Cutaneous angiosarcoma (CAS) is a rare soft-tissue sarcoma of vascular endothelial origin. Paclitaxel (PTX) and docetaxel (DTX) are used as systemic chemotherapy; however, chemoresistance often occurs in CAS. Switching one taxane to the other (i.e., PTX to DTX, or vice versa) is an option when the first taxane is no longer effective in malignant cancers such as ovarian or breast cancer. However, the efficacy of the same strategy in CAS has not been reported. Herein, we report the clinical response of switching one taxane-based chemotherapy to the other in CAS patients with resistance to the first taxane. Twelve CAS patients were included for analyses. In all patients, the median overall survival from the start of the first taxane treatment was 29.0 months (range, 6.47-58.5). During the first taxane, the median PFS for all patients was 5.96 months (1.81-47.1). Similarly, the median (range) PFS for all patients during the second taxane was 5.87 months (1.60-18.2). Furthermore, the median OS was 22.7 months (PTX to DTX) and 39.5 months (DTX to PTX) (p = 0.307). The median PFS during the first taxane was 5.14 (PTX to DTX) and 12.5 months (DTX to PTX), respectively (p = 0.380). The median PFS during the second taxane was 3.5 (PTX to DTX) and 7.1 months (DTX to PTX), respectively (p = 0.906). The objective response rate, defined as the sum of complete response (CR) and partial response (PR) rates, was 16.7%. The disease control rate, defined as the sum of CR, PR, and stable disease rates, was 50%. The frequency of adverse events during the second taxane was the same between the two groups (p > 0.999). Our report suggests that CAS patients could benefit from the second taxane treatment if the tumor is resistant to the first taxane.

Magnetic Resonance Imaging-negative Acute Inflammatory Myelopathy following Severe Acute Respiratory Syndrome Coronavirus 2 Infection.

A 55-year-old woman was admitted to our hospital because of gait disturbance and urinary retention that acutely emerged 1 week after severe acute respiratory syndrome coronavirus 2 infection. Acute inflammatory myelopathy was clinically suspected, based on bilateral lower-limb weakness with an extensor plantar response and an elevated immunoglobulin G level in the cerebrospinal fluid. Whole-spine magnetic resonance imaging findings were normal. The central conduction time was extended, based on somatosensory evoked potentials. Her lower-limb weakness was partially ameliorated with immunosuppressive therapy. Postinfectious myelopathy is a rare neurological complication of coronavirus disease 2019 and can develop with normal radiological findings.

Repeated and targeted transfer of angiogenic plasmids into the infarcted rat heart via ultrasound targeted microbubble destruction enhances cardiac repair.

AIMS: Ultrasound-targeted microbubble destruction (UTMD) uses ultrasound energy to selectively deliver genes into the myocardium using plasmids conjugated to microbubbles. We hypothesized that repeated delivery of stem cell-mobilizing genes could boost the ability of this therapy to enhance cardiac repair and ventricular function after a myocardial infarction. METHODS AND RESULTS: Beginning 7 days after coronary artery ligation, stem cell factor (SCF) and stromal cell-derived factor (SDF)-1α genes were administered to adult rats using 1, 3, or 6 UTMD treatments (repeat 1, 3, and 6 groups) at 2-day intervals (control=6 treatments with empty plasmid). Cardiac function (echocardiography) and myocardial perfusion (myocardial contrast echocardiography) were assessed on Days -7, 0, and 24 relative to the first treatment. Histological and biochemical assessments were performed on Day 24. Multiple UTMD treatments were associated with an increased presence of myocardial SCF and SDF-1α proteins and their receptors (vs. control and Repeat 1). All UTMD recipients exhibited increased vascular densities and smaller infarct regions (vs. control), with the highest ventricular densities in response to multiple treatments. Myocardial perfusion and ventricular function at Day 24 also improved progressively (vs. control) with the number of UTMD treatments. CONCLUSIONS: Targeted ultrasound delivery of SCF and SDF-1α genes to the infarcted myocardium recruited progenitor cells and increased vascular density. Multiple UTMD treatments enhanced tissue repair, perfusion, and cardiac function. Repeated UTMD therapy may be applied to tailor the number of interventions required to optimize cardiac regeneration after an infarction.

Efficacy of a high dosage of donepezil for Alzheimer's disease as examined by single-photon emission computed tomography imaging.

BACKGROUND: The efficacy of donepezil 10 mg/day against Alzheimer's disease (AD) was examined, with a primary focus on changes in cerebral blood flow (CBF) as determined by single-photon emission computed tomography imaging. METHODS: The subjects were 24 outpatients who had been diagnosed with probable AD, which had progressed to advanced AD. Mini-Mental State Examination and Alzheimer's Disease Assessment Scale (ADAS) scores were determined before and after the donepezil dosage increase. (99m) Tc-ethylcysteinate dimer single-photon emission computed tomography was performed to evaluate changes in CBF. Then, a comparative study evaluated changes after the donepezil dosage increased. RESULTS: After the donepezil dosage increase, adverse effects associated with gastrointestinal symptoms were observed in one patient, and irritability was observed in three. The average Mini-Mental State Examination score changed from 15.25 ± 6.24 to 14.67 ± 6.07; significant changes were not observed. Seventeen subjects were evaluated with the Alzheimer's Disease Assessment Scale-cognitive subscale. After the dosage increase, the average subscale score decreased from 24.52 ± 13.39 to 21.56 ± 9.14, and significant improvement was observed (P = 0.021). With respect to changes in the CBF, the values of all three indicators decreased after the higher dosage increased CBF. However, no significant differences were observed in CBF. Analysis performed after the donepezil dosage increase revealed significant increases in CBF in the right occipital and temporal lobes, left temporal lobe, right parietal lobe, and both parts of the posterior cerebellum. CONCLUSION: Increasing the donepezil dosage from 5 mg/day to 10 mg/day is effective for the treatment of AD.

A case of allergic bronchopulmonary mycosis due to Schizophyllum commune with elevated serum carcinoembryonic antigen levels.

A 78-year-old Japanese woman without any history of asthma or smoking presented prolonged cough. Laboratory data showed elevated serum CEA levels and a chest CT revealed a mass with abnormal uptake in the left lower lobe. One month later, the mass spontaneously regressed, and CEA levels improved. However, the symptoms progressed during the observation period without treatment. Chest radiograph findings revealed collapse of the right middle lobe, and Schizophyllum commune was isolated from the mucous plugs; the patient was diagnosed with allergic bronchopulmonary mycosis (ABPM). Herein, we report the first case of ABPM caused by S. commune with elevated CEA levels and mimicking lung cancer.

GFAP-Negative Subcutaneous Sacrococcygeal Extraspinal Ependymoma.

Ependymomas are slowly growing glial tumors derived from the ependymal cells and usually occur in the central nervous system (CNS). Ependymomas rarely occur outside of the CNS and they are called extraspinal ependymomas. In spite of their metastatic potential, extraspinal ependymomas can be misdiagnosed for other benign mass like pilonidal cysts. The diagnosis is confirmed by histopathology and most of the cases are known to show glial fibrillary acidic protein (GFAP), S-100 protein, and keratin (AE1AE3) immunoreactivity. Herein, we present a case of GFAP-negative ependymoma, which presented as asymptomatic subcutaneous tumor of the left buttock and was clinically misdiagnosed as epidermal cyst. Our case indicates that ependymomas cannot be ruled out by lack of GFAP immunoreactivity and an asymptomatic subcutaneous mass could be a malignant tumor like ependymomas, which requires careful examinations.

Community-based lifestyle modification of cardiovascular disease risks in middle-aged Japanese: a 27-month update.

Lifestyle modification is the cornerstone of preventive management for people with cardiovascular disease risks, such as obesity, hypertension, dyslipidemia and diabetes. This study investigated the effect of a 27-month community-based lifestyle intervention on the reduction of cardiovascular disease risks in middle-aged Japanese. Of 549 participants with cardiovascular disease risk factors of overweight, hypertension, dyslipidemia or diabetes enrolled in this non-randomized controlled study, 397 participants aged 39-71 years old completed all 3 serial surveys at baseline, 15 months and 27 months. For the intervention group (39 males and 174 females), 31 specific interventions including individual counselling and group sessions were conducted. The control group (64 males and 120 females) only received 7 newsletters providing health information and results of health checkups. Multiple logistic regression analysis adjusted for sex, each baseline risk category and age category showed that the proportion of those who were overweight or showed dyslipidemia risk were significantly lower in the intervention group only at 27 months [Odds ratio (OR): 0.43 (95% CI 0.20-0.94), OR: 0.43 (95% CI 0.21-0.87), respectively] and the proportion of those showing diabetes risk was significantly lower in the intervention group at both 15 months [OR: 0.42 (95% CI 0.18-0.97)] and 27 months [OR: 0.56 (95% CI 0.32-0.99)]. In conclusion, the 27-month community-based lifestyle modification of cardiovascular disease risks shows significant reductions in risks of diabetes, overweight and dyslipidemia in middle-aged Japanese.

Daily intake of green and yellow vegetables is effective for maintaining bone mass in young women.

The increasing proportion of underweight young women may lead to an increase in those with low bone mass. The present study investigated whether bone mass level is associated with lifestyle factors among young Japanese women. A total of 103 Japanese female college students aged 20-21 majoring in food science participated in this cross-sectional study. We measured bone area ratio at the os calcis using quantitative ultrasound (QUS) and assessed lifestyle factors including diet and physical activity using a self-reported questionnaire. Bone area ratio was defined as a proportion of bone substance in a cross section of os trabeculare. Ninety-one subjects who completed the questionnaire were categorized into two groups according to the average bone area ratio of the 103 subjects (30.9%), calculated based on the screening method for osteoporosis prevention: 69 subjects with normal bone mass (bone area ratio: 36.2 +/- 3.8%) and 22 subjects with low bone mass (bone area ratio: 28.1 +/- 1.6%). In normal group, 12 subjects (17.4%) had a dietary habit of not daily intake of green and yellow vegetables, such as carrot and spinach, while this occurred in 10 subjects (45.5%) in low group (P = 0.007). Adjusted logistic regression analyses showed that the subjects without daily intake of green and yellow vegetables had almost 5-fold risk of low bone mass, compared to the subjects having daily intake of the vegetables [Odds ratio: 4.96 (95%CI 1.36-18.18)]. In conclusion, daily intake of green and yellow vegetables is effective for maintaining bone mass in young women.

High attendance at a lifestyle intervention program is important to reduce risks related to metabolic syndrome in middle-aged Japanese.

Evaluating attendance at health education programs is important to obtain a more comprehensive evaluation of the program impact. This study investigated whether attendance at a lifestyle intervention program in a community setting would reduce risks related to metabolic syndrome. Of 545 subjects with risks related to metabolic syndrome, i.e. overweight, hypertension, dyslipidemia or diabetes, participated in this non-randomized control study, 389 subjects aged 40-71 years completed the surveys at baseline and 27 months. Intervention group (39 males and 168 females) was provided 3 individual counseling plus 28 group sessions conducted monthly on average, whereas control group (64 males and 118 females) received only 7 health information newsletters by mail. Intervention group was subcategorized into two groups according to the median attendance (87.1%): 106 subjects with high attendance (93.8 +/- 4.7%) and 101 subjects with low attendance (68.6 +/- 16.0%). Logistic regression analyses adjusted for age and baseline value showed that among males, the proportion with dyslipidemia risk was lower only in high attendance group compared with that in control group at 27 months [Odds ratio (OR): 0.11 (95%CI 0.02 - 0.51)] and among females, the proportion of overweight was lower only in high attendance group [OR: 0.24 (95%CI 0.07 - 0.81)]. In females, the mean total risk score calculated by adding the number of the 4 risks present decreased only in high attendance group (p < 0.001). In conclusion, high attendance at a lifestyle intervention program impacts the reduction of risks related to metabolic syndrome in a Japanese community setting.

Predictive factors of response to pulse methylprednisolone therapy in patients with alopecia areata: A follow-up study of 105 Japanese patients.

Pulse corticosteroid therapy is effective for alopecia areata (AA) in the early stage. The risk and efficacy of this therapy for patients with several backgrounds, however, remains controversial. To explore the predictive factors of the response and risk factors of this therapy, data from 105 AA patients treated with methylprednisolone (500 mg) i.v. for 3 days consecutively in our facility were retrospectively analyzed. Among good responders, longer time from the onset to therapy was correlated with longer time required for hair regrowth (P = 0.037, n = 27). Multivariate models demonstrated that "severity", "relapse" and longer "duration from the latest onset" were significantly and independently associated with poorer outcome (P < 0.01). "History of atopic dermatitis (AD)" was also associated with poorer outcome, but this correlation could be explained by the effect that duration from the latest onset of AA was longer among participants with AD. We propose that earlier initiation of pulse corticosteroid therapy is preferable for better outcome of AA, particularly among patients with AD. Clinicians should be mindful of the occurrence of mild adverse effects in the elderly patients.

c-kit dysfunction impairs myocardial healing after infarction.

BACKGROUND: We hypothesized that c-kit receptor function in the bone marrow is important for facilitating healing, leading to efficient cardiac repair after myocardial infarction (MI). METHODS AND RESULTS: We used Kit(W)/Kit(W-v) c-kit mutant mice and their wild-type littermates to assess the importance of c-kit function in cardiac remodeling after coronary ligation. We found that mutant mice developed 1.6-fold greater ventricular dilation (P=0.008) attributable to a 1.3-fold greater infarct expansion by day 14 after MI (P=0.01). The number of proliferating smooth muscle alpha-actin expressing cells was 1.8-fold lower in mutant mice at day 3 (P<0.01), resulting in a 1.6 to 1.8-fold reduction in total regional nonvascular smooth muscle alpha-actin expressing cells by both microscopy and flow cytometry (P<0.001 for both). This decrease was accompanied by a 1.4-fold reduction in the number of CD31 expressing blood vessels (P<0.05). Prior transplantation of wild-type bone marrow cells into mutant mice rescued the efficient establishment of vessel-rich repair tissue by inducing a 1.5-fold increase in nonvascular smooth muscle alpha-actin expressing cells and CD31 expressing blood vessels (P<0.05 for both). The increased recruitment of cells into the infarct region in the chimeric mice was associated with reduced infarct expansion (P<0.03) compared to wild-type levels. CONCLUSIONS: Bone marrow c-kit function critically impacts the myofibroblast repair response in infarcted hearts. Interventions that increase the infiltration of c-kit+ cells to the infarcted heart may potentiate this endogenous repair response, prevent infarct expansion, and improve the recovery of cardiac function after MI.

Human angiogenic cell precursors restore function in the infarcted rat heart: a comparison of cell delivery routes.

BACKGROUND: We recently isolated angiogenic cell precursors (ACPs) from human blood, which can induce angiogenesis in vitro. AIMS: In the present study, we used a nude rat model of ischaemic cardiomyopathy to compare the efficacy of intramyocardial and intracoronary ACP implantation, and to evaluate effects on cardiac function, scar size and angiogenesis. METHODS AND RESULTS: Adult nude rats underwent coronary artery ligation. Six days later, ACPs (characterized in vitro prior to implantation) or culture media were injected directly into the ischaemic myocardial region or into the coronary artery via the aorta. Cardiac function was measured by echocardiography prior to and at 2 and 4 weeks after implantation. Scar morphology, cell engraftment, and myocardial angiogenesis were evaluated at 4 weeks. Two and four weeks after implantation, cardiac function declined in both of the control groups but improved in both the intramyocardial and intracoronary ACP groups. Significant reductions in myocardial scar area were only observed in the intramyocardial ACP group, while increases in blood vessel density, which were observed in all ACP recipients, were greatest in the intracoronary ACP group. CONCLUSIONS: Human ACPs, delivered via intramyocardial or intracoronary injection, engrafted into damaged cardiac tissue and improved cardiac function within 4 weeks through effects on scar morphology and blood vessel formation.

The MRL mouse heart does not recover ventricular function after a myocardial infarction.

INTRODUCTION: Murphy Roth Large (MRL) mice have a remarkable regenerative capacity. A recent report demonstrated rapid cardiac healing in these mice following cryogenically induced right ventricular injury, suggesting the potential for new regenerative therapies to restore cardiac function in mammals. We therefore evaluated the cardiac regenerative wound-healing response and functional recovery of MRL mice in response to a clinically relevant left ventricular coronary ligation. METHODS: Female MRL/MpJ+/+ and C57BL/6 mice underwent left coronary artery ligation. Cardiac function was evaluated by echocardiography at Days 0, 5, 15, and 60. At Day 96, invasive hemodynamics were assessed by pressure-volume loops using a Millar catheter. Hearts were perfusion fixed for histomorphometric analysis at Days 5, 15, and 96. Some hearts were fresh frozen at Days 5 and 15 for immunohistochemical analysis and digital quantitation of blood vessel density (CD31) and cellular proliferation (Ki67). RESULTS: MRL mice healed ear punch wounds (89% reduction in area) more extensively than C57BL/6 mice (28% reduction in area) but did not differ functionally from C57BL/6 animals before or after coronary ligation. In addition, blood vessel density and cell proliferation were similar between the two strains. CONCLUSIONS: Although MRL mice rapidly healed ear injury, they did not exhibit regeneration of the left ventricle or enhanced functional improvement in response to coronary ligation. The prospect of cardiac regeneration after myocardial infarction will require further studies designed to elucidate the possible mechanisms of functional restoration.