Dar-Ming Lai

Loss of Cxcl12/Sdf-1 in adult mice decreases the quiescent state of hematopoietic stem/progenitor cells and alters the pattern of hematopoietic regeneration after myelosuppression

The C-X-C-type chemokine Cxcl12, also known as stromal cell-derived factor-1, plays a critical role in hematopoiesis during fetal development. However, the functional requirement of Cxcl12 in the adult hematopoietic stem/progenitor cell (HSPC) regulation was still unclear. In this report, we developed a murine Cxcl12 conditional deletion model in which the target gene can be deleted at the adult stage. We found that loss of stroma-secreted Cxcl12 in the adult led to expansion of the HSPC population as well as a reduction in long-term quiescent stem cells. In Cxcl12-deficient bone marrow, HSPCs were absent along the endosteal surface, and blood cell regeneration occurred predominantly in the perisinusoidal space after 5-fluorouracil myelosuppression challenge. Our results indicate that Cxcl12 is required for HSPC homeostasis regulation and is an important factor for osteoblastic niche organization in adult stage bone marrow.

GRP78 expression correlates with histologic differentiation and favorable prognosis in neuroblastic tumors

Glucose‐regulated protein 78 (GRP78), an endoplasmic reticulum protein, is essential for the differentiation of neuroblastoma cells and is selectively induced when the cells are undergoing apoptosis. These findings suggest that GRP78 may affect the tumor behavior of neuroblastoma. Our study evaluates the association of clinicopathologic factors and patient survival with the expression of GRP78 in patients with neuroblastoma. GRP78 expression in 68 neuroblastic tumors was investigated semiquantitatively by immunohistochemistry. GRP78 mRNA and protein levels in 7 tumor tissues were also quantified by real‐time PCR and Western blot respectively and correlated well with the immunohistochemical results. Forty (58.8%) of the 68 neuroblastic tumors showed positive GRP78 expression. The percentage of positive GRP78 immunostaining increased as the tumor histology became differentiated (p = 0.001). Furthermore, positive GRP78 expression strongly correlated with early clinical stages (P = 0.002) but inversely correlated with MYCN amplification (p = 0.001). Kaplan‐Meier analysis showed that patients with positive GRP78 expression did have better survival than those with negative expression (5‐year survival rate, 72.9% and 23.4% respectively, p < 0.001). Multivariate analysis further showed that GRP78 expression was an independent prognostic factor. Moreover, GRP78 expression predicted better survival in patients with either undifferentiated or differentiated histologies. GRP78 expression still had significant prognostic value when the analysis was restricted to tumors of advanced stages or without MYCN amplification. Thus, GRP78 can serve as a novel independent favorable prognostic factor for patients with neuroblastoma.

Complexity of heart rate variability predicts outcome in intensive care unit admitted patients with acute stroke

Background Heart rate variability (HRV) has been proposed as a predictor of acute stroke outcome. This study aimed to evaluate the predictive value of a novel non-linear method for analysis of HRV, multiscale entropy (MSE) and outcome of patients with acute stroke who had been admitted to the intensive care unit (ICU). Methods The MSE of HRV was analysed from 1 h continuous ECG signals in ICU-admitted patients with acute stroke and controls. The complexity index was defined as the area under the MSE curve (scale 1–20). A favourable outcome was defined as modified Rankin scale 0–2 at 3 months after stroke. Results The trends of MSE curves in patients with atrial fibrillation (AF) (n=77) were apparently different from those in patients with non-AF stroke (n=150) and controls (n=60). In addition, the values of complexity index were significantly lower in the patients with non-AF stroke than in the controls (25.8±.3 vs 32.3±4.3, p<0.001). After adjustment for clinical variables, patients without AF who had a favourable outcome were significantly related to higher complexity index values (OR=1.15, 95% CI 1.07 to 1.25, p<0.001). Importantly, the area under the receiver operating characteristic curve for predicting a favourable outcome of patients with non-AF stroke from clinical parameters was 0.858 (95% CI 0.797 to 0.919) and significantly improved to 0.903 (95% CI 0.853 to 0.954) after adding on the parameter of complexity index values (p=0.020). Conclusions In ICU-admitted patients with acute stroke, early assessment of the complexity of HRV by MSE can help in predicting outcomes in patients without AF.

Increase of adenosine A1 receptor gene expression in cerebral ischemia of Wistar rats

In an attempt to know the role of adenosine A1 receptor in cerebral ischemia, the present study employed the ligation of bilateral carotid arteries to induce ischemia in Wistar rats. Changes of gene expression of adenosine A1 receptor in cerebral cortex of ischemic rats were compared with normal sham control and reperfusion group that received regular blood flow after a transient ischemia. The mRNA level of adenosine A1 receptor in cerebral cortex was markedly raised by this artificial ischemia. Also, reperfusion reversed this elevation to a level near the control. This change was also observed at the protein level using Western blot analysis of adenosine A1 receptor. The raised protein level of adenosine A1 receptor by ischemia was reversed to normal level after reperfusion. These data suggest that the gene expression of adenosine A1 receptor was increased by ischemia probably due to the compensative response of brain. The raised adenosine A1 receptor may play a protective role in these damaged tissues.

The Influence of Biologic Factors on the Surgical Decision in Advanced Neuroblastoma

BackgroundMolecular markers greatly affect the outcome of neuroblastoma. This study evaluated the influence of Trk-A and myelocytomatosis viral-related oncogene, neuroblastoma-derived (MYCN) on the role of surgery in advanced neuroblastoma.MethodsTen stage 3 and 35 stage 4 neuroblastoma patients were included. Tumor resection was classified into gross total resection (GTR) and incomplete resection. Patients were classified into three biological risk groups according to Trk-A expression and myelocytomatosis viral-related oncogene, neuroblastoma-derived (MYCN) status in tumor tissues studied by immunohistochemistry and fluorescence in situ hybridization, respectively: low risk (positive Trk-A and normal MYCN), intermediate risk (negative Trk-A and normal MYCN), and high risk (positive or negative Trk-A and MYCN amplification). The effect of tumor resection on prognosis was studied and stratified according to the risk grouping.ResultsGTR was achieved in 21 patients (46.7%) with a higher complication rate (33% vs. 8% in the incomplete resection group, P = .036). GTR was easier to achieve in low-risk tumors than in intermediate- or high-risk tumors (12 of 13, 4 of 17, and 5 of 15, respectively; P < .001). GTR predicted a favorable prognosis for intermediate-risk patients (P = .037; log-rank test), but not for low- or high-risk patients because of the overall favorable and poor prognosis, respectively.ConclusionsGTR carries a potentially higher possibility of complication. Although GTR can be achieved easily in low-risk neuroblastoma patients with a favorable prognosis, surgeons should do their best to achieve GTR for intermediate-risk patients to improve outcome. Nevertheless, sacrificing vital organs to achieve GTR for high-risk patients is not justified.

Complexity of Heart Rate Variability Can Predict Stroke-In-Evolution in Acute Ischemic Stroke Patients.

About one-third of acute stroke patients may experience stroke-in-evolution, which is often associated with a worse outcome. Recently, we showed that multiscale entropy (MSE), a non-linear method for analysis of heart rate variability (HRV), is an early outcome predictor in non-atrial fibrillation (non-AF) stroke patients. We aimed to further investigate MSE as a predictor of SIE. We included 90 non-AF ischemic stroke patients admitted to the intensive care unit (ICU). Nineteen (21.1%) patients met the criteria of SIE, which was defined as an increase in the National Institutes of Health Stroke Scale score of ≥2 points within 3 days of admission. The MSE of HRV was analyzed from 1-hour continuous ECG signals during the first 24 hours of admission. The complexity index was defined as the area under the MSE curve. Compared with patients without SIE, those with SIE had a significantly lower complexity index value (21.3 ± 8.5 vs 26.5 ± 7.7, P = 0.012). After adjustment for clinical variables, patients with higher complexity index values were significantly less likely to have SIE (odds ratio = 0.897, 95% confidence interval 0.818–0.983, P = 0.020). In summary, early assessment of HRV by MSE can be a potential predictor of SIE in ICU-admitted non-AF ischemic stroke patients.

Hyperacute cerebral aneurysm rerupture during CT angiography

OBJECT The object of this study was to identify the clinical features and outcomes of a subgroup of patients with aneurysmal subarachnoid hemorrhage (SAH) who had active contrast extravasation from a ruptured aneurysm during initial cerebral CT angiography (CTA). METHODS The authors performed a retrospective study of spontaneous SAH cases involving patients treated at their institute. They identified 9 cases in which active contrast extravasation was evident on the initial CT angiogram. Another 12 similar cases were also identified in a literature review and data was gathered from these cases to evaluate the outcomes. RESULTS Analysis of all 21 cases revealed that the overall outcomes in cases characterized by active aneurysmal bleeding during CTA were poor. Seventy-six percent of patients had unfavorable results. Patients who showed poor neurological status at presentation died no matter what kind of treatment they received. In contrast, patients who presented with good neurological status initially had a chance of favorable outcome. Among the patients with good initial neurological status, most demonstrated rapid deterioration of their condition during the CTA examination; only those who received immediate and effective decompressive surgery and aneurysm obliteration had good results. CONCLUSIONS Active aneurysmal rebleeding during CTA is an uncommon but devastating event. Though the mortality of this distinct group of patients remains high, a clinical subgroup may benefit from immediate surgery. Patients with good initial neurological status who show rapid neurological deterioration may still have a favorable outcome if they undergo timely and successful decompressive surgery and proper aneurysm obliteration. Patients who present with poor neurological status do badly, and there is no effective treatment for such patients.

Identification of Atrial Fibrillation by Quantitative Analyses of Fingertip Photoplethysmogram

Atrial fibrillation (AF) detection is crucial for stroke prevention. We investigated the potential of quantitative analyses of photoplethysmogram (PPG) waveforms to identify AF. Continuous electrocardiogram (EKG) and fingertip PPG were recorded simultaneously in acute stroke patients (n = 666) admitted to an intensive care unit. Each EKG was visually labeled as AF (n = 150, 22.5%) or non-AF. Linear and nonlinear features from the pulse interval (PIN) and peak amplitude (AMP) of PPG waveforms were extracted from the first 1, 2, and 10 min of data. Logistic regression analysis revealed six independent PPG features feasibly identifying AF rhythm, including three PIN-related (mean, mean of standard deviation, and sample entropy), and three AMP-related features (mean of the root mean square of the successive differences, sample entropy, and turning point ratio) (all p < 0.01). The performance of the PPG analytic program comprising all 6 features that were extracted from the 2-min data was better than that from the 1-min data (area under the receiver operating characteristic curve was 0.972 (95% confidence interval 0.951–0.989) vs. 0.949 (0.929–0.970), p < 0.001 and was comparable to that from the 10-min data [0.973 (0.953–0.993)] for AF identification. In summary, our study established the optimal PPG analytic program in reliably identifying AF rhythm.

Angiopoietin‐like protein 1 expression is related to intermuscular connective tissue and cartilage development

Angptl1, a member of the angiopoietin‐related protein family, is known to regulate angiogenesis, but little is known of its potential role in other processes. To identify the expression pattern and possible role of angptl1 during embryogenesis, we used gene targeting to generate angptl1‐deficient, nLacZ knockin mice. Staining for β‐galactosidase from embryonic day 9.5 to 6 months of age revealed that angptl1 was initially expressed in the paraxial mesoderm. Expression then shifted to intermuscular connective tissue (fascial plane), joint capsules, and perichondrium (laryngo‐trachea, ribs, and long bones), but not the muscles. The vasculature, central and peripheral nervous systems, digestive, respiratory, and other major organ systems did not show any angptl1 expression. This expression pattern suggests that angptl1 is related to development of the connective tissue and cartilage. Lack of phenotype in mutant mice may be due to a functional redundancy from other related factors. Developmental Dynamics 236:2643–2652, 2007.

Effect of mannitol on cerebrovascular pressure reactivity in patients with intracranial hypertension

BACKGROUND/PURPOSE Mannitol is commonly used in patients with increased intracranial pressure (ICP), but its effect on cerebrovascular pressure reactivity (CVPR) is uncertain. We analyzed the changes of pressure reactivity index (PRx) during the course of mannitol treatment. METHODS Twenty-one patients who received mannitol treatment for increased ICP were recruited prospectively. Continuous waveforms of arterial blood pressure (ABP) and ICP were collected simultaneously for 60 minutes (10 minutes at baseline and 50 minutes since mannitol administration) during 37 events of mannitol treatment. The correlation coefficients between the mean ABP and ICP were averaged every 10 minutes and labeled as the PRx. The linear correlation of six time points of PRx in each event was calculated to represent the trend of CVPR changes. The negative slope of correlation was defined as improvement in CVPR under mannitol treatment and vice versa. RESULTS At baseline, the average of ICP was 26.0 ± 9.1 mmHg and the values of PRx were significantly correlated with ICP (p = 0.0044, r = 0.46). After mannitol administration, the average of ICP decreased significantly to 21.2 ± 11.1 mmHg (p = 0.036), and CVPR improved in 59.4 % of all events. Further analysis showed that low baseline cerebral perfusion pressure was the only hemodynamic parameter significant association with the improvement of CVPR after mannitol treatment (p = 0.039). CONCLUSION Despite lowering ICP, mannitol may have diverse effects on CVPR in patients with intracranial hypertension. Our study suggests that mannitol infusion may have a beneficial effect on CVPR, particularly in those with a low cerebral perfusion pressure at baseline.