Assessment of wall shear stress in the common carotid artery of healthy subjects using 3.0-tesla magnetic resonance

BACKGROUND

Wall shear stress (WSS) has been proven to play a critical role in the formation and development of atherosclerotic plaques. Measurement of WSS in vivo is significant for the clinical assessment of atherosclerosis.

PURPOSE

To assess the magnitude and distribution of local WSS in the common carotid artery (CCA) in vivo using 3.0T magnetic resonance (MR).

MATERIAL AND METHODS

The common carotid artery of eight healthy volunteers was studied using a cine phase-contrast MR sequence. A three-dimensional paraboloid model was applied to fit the velocity profiles, and the WSS values were calculated. The cross-sectional area, average flow velocity, maximum velocity, and flow rate were also obtained.

RESULTS

Mean WSS was 0.850 +/- 0.195 (range 0.132-3.464) N/m(2) for the common carotid arteries; the spatial and temporal distribution and change of WSS were displayed. During a cardiac cycle, the mean velocity was 22.8 +/- 3.5 (16.9-28.3) cm/s, blood flow rate 8.03+/-1.45 (5.73-10.72) ml/s, and luminal vessel area 34.94+/-7.06 (24.25-49.01) mm(2).

CONCLUSION

Local WSS values in CCAs can be measured using 3.0T MR imaging combined with image-processing techniques. Intersubject variations were found in the distribution and magnitude of wall shear stress as well as in the flow profile pattern in CCAs, which may be caused by different vessel morphologies.

Quantification of brain creatine concentration using PRESS sequence and LCModel: comparison with HPLC method

To investigate the accuracy for quantification of brain total creatine (Cr) concentration using in vivo long echo time (TE) PRESS sequence with an external standard and LCModel. Ten swine and an external standard containing a detectable compounds of known concentration were studied by using 1.5 T GE Signa scanner and the standard head coil; the single-voxel proton magnetic resonance spectroscopy (1H-MRS) data was acquired from the 20-mm cubic VOI which was placed in the swine brain and external standard respectively by using the PRESS sequence with TE=135 msec, TR=1500 msec, and 128 scan averages. The quantification of Cr was accomplished by the linear combination of model spectra (LCModel). After MRS examination, each animal was sacrificed, and in vitro Cr concentration was analyzed by high performance liquid chromatography (HPLC). In the MRS group, the mean concentration of Cr was 9.37+/-0.137mmol/kg; in the HPLC group, the mean concentration of Cr was 8.905+/-0.126 mmol/kg. There were no statistically significant differences between two methods (P=0.491), which indicated that long TE PRESS sequence with an external standard can accurately detect the brain Cr concentration. The application of LCModel introduces more convenience for the MRS quantification.

Diet-induced central obesity and insulin resistance in rabbits

The present study was designed to examine whether rabbits fed a diet containing high fat and sucrose could develop obesity and insulin resistance (IR), the major pathophysiological features of metabolic syndrome. Male Japanese white rabbits were fed either a normal chow diet (control) or high fat and sucrose diet (HFSD) for 36 weeks. Plasma levels of triglycerides (TG), total cholesterol (TC), glucose and insulin were measured. To evaluate glucose metabolism, we performed an intravenous glucose tolerance test. In addition, we compared adipose tissue accumulation in HFSD-fed rabbits with that in normal rabbits. HFSD constantly and significantly led to an increase in body weight of HFSD-fed rabbits, caused by significantly higher visceral adipose tissue accumulation. Although there were no differences in plasma TG, TC, glucose, insulin levels and blood pressure between the two groups, HFSD-fed rabbits showed impaired glucose clearance associated with higher levels of insulin secretion compared to control rabbits. Our results showed that HFSD induced IR and increased adipose accumulation in rabbits, suggesting that HFSD-fed rabbits may become a model for research on human IR and obesity.

Attenuation of heart rate control and neural degeneration in nucleus ambiguus following chronic intermittent hypoxia in young adult Fischer 344 rats

Chronic intermittent hypoxia (CIH) attenuates baroreflex control of heart rate (HR). In this study, we assessed whether CIH exposure reduced nucleus ambiguus (NA) control of HR and induced neural degeneration in the NA. Fischer 344 (age: 3-4 months) rats were exposed to either room air (RA: normoxia) or intermittent hypoxia for 35-50 days. At the end of these exposures, animals were anesthetized with pentobarbital. HR responses to arterial blood pressure (AP) changes induced by phenylephrine (PE) and sodium nitroprusside (SNP) were measured. In another set of rats, HR and AP responses to L-glutamate (L-Glu) microinjections (10 mM, 20 nl) into the left NA and electrical stimulation of the left cervical vagus nerve at 1-30 Hz (0.5 mA, 1 ms) for 20 s were measured. Brainstem slices at the level of -800, -400, 0, +400, +800 microm relative to the obex were processed in additional rats using Nissl staining. The NA was identified by retrogradely labeling vagal motoneurons using the tracer tetramethylrhodamine dextran (TMR-D) which was injected into the ipsilateral nodose ganglion. We found that CIH significantly 1) reduced the baroreflex control of HR (slope RA: -1.2+/-0.2 bpm/mmHg; CIH -0.5+/-0.1 bpm/mmHg; P<0.05); 2) attenuated the HR responses to l-Glu injections into the NA [HR: -280+/-15 (RA) vs. -235+/-16 (CIH) beats/min; P<0.05]; 3) augmented the HR responses to electrical stimulation of the vagus (P<0.05); 4) induced a significant cellular loss in the NA region (P<0.05). Thus, CIH induces a cell loss in the NA region which may contribute to attenuation of baroreflex sensitivity and NA control of HR following CIH.

A comparative study of hFIX expression mediated by rAAV8 and rAAV1 administrated intramuscularly

BACKGROUND

Recombinant AAV serotype 8 (rAAV8) vector is relatively new for gene therapy. In this study, the hFIX expression mediated by rAAV8 injected intramuscularly was compared with that by rAAV1.

METHODS

rAAV8-hFIX or rAAV1-hFIX viruses were injected intramuscularly into two hind limbs of mice at doses of 5x10(10) gc and 2.5x10(12) gc (genome copy). The hFIX expression in the mouse plasma was detected by ELISA, APTT and Western blotting. The virus distribution was analyzed by immunohistochemical assay.

RESULTS

When the mice were infected with 5x10(10) gc virus, high levels of hFIX in the plasma of five rAAV8-hFIX virus-infected mice were detected 2 weeks after injection. A hFIX peak above 5000 ng/mL appeared between 2 and 6 weeks after injection. Relatively low levels of hFIX were detected in the plasma of rAAV1-hFIX virus-infected mice 2 weeks after injection. An hFIX peak above 3000 ng/mL appeared between 4 and 10 weeks after injection. However, much lower levels of hFIX were detected in mice infected with higher dose of rAAV8 virus. The hFIX in the mouse plasma was active biologically. The viruses were distributed mainly in the muscles of hind limbs.

DISCUSSION

Gene expression mediated by rAAV8 was sooner and stronger than that by rAAV1 after intramuscular administration. Inhibition might have been triggered markedly by rAAV8 at high doses.

Fluorescence diffuse optical tomography with functional and anatomicala prioriinformation: feasibility study

Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo.

Pre-medications of weekly taxanes in advanced non-small cell lung cancer

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Background: Taxane is a widely accepted treatment in advanced non-small cell lung cancer (NSCLC). However, a standard pre-medication for weekly taxane has not been established at present. We conducted this study to evaluate the efficacy,safety and pre-medication of weekly paclitaxel /docetaxel schedule in the treatment of advanced NSCLC and to obtain an optimal pre-medication protocol for weekly paclitaxel /docetaxel. Methods: From December 2001 to June 2006, 78 patients with advanced NSCLC (Stage III, IV) were recruited from Department of Chemotherapy, Jiangsu Cancer Hospital and Research Institute. Eleven cases were treated with paclitaxel 80–100 mg/m 2 by intravenous infusion(ivi)on days 1 and 8, 23 cases were treated with paclitaxel 50–80 mg/m2 ivi on days 1, 8 and 15, 14 cases were treated with docetaxel 25–35 mg/m2 ivi on days 1,8 and 15,30 cases were treated with docetaxel 35–45 mg/m2 ivi on days 1 and 8, all combined with a platinum(cisplatin, oxaliplatin or carboplatin), followed by 1 week rest. Four pre-medications were attempted. Results: All 78 patients received a total of 202 courses of treatment. Dose limiting toxicity was myelosuppression. Grade 3 and 4 leukopenia occurred in 19.2% (15/78) of patients. Of the 56 eligible patients who completed at least 2 courses, no patient had a complete response, 20 achieved a partial response and 5 patients showed progression. Toxicity profile of pre-medications included: hypersensitivity (1 case), hypopotassemia (8 cases), myasthenia (5 cases), hiccup (1 case), infection (2 cases). No treatment related death occurred in this study. Conclusions: Weekly administration of paclitaxel/docetaxel is a safe and active protocol for Chinese patients with advanced NSCLC. Our recommendations for weekly pre-medication of taxane are: dexamethasone 2.25 mg-7.5 mg orally 12 h and 2 h before, promethazine 25 mg intramuscularly and cimetidine 600 mg ivi 30 min before paclitaxel; oral dexamethasone 4.5 mg-7.5 mg twice daily for three consecutive days (the day before, the day of, and the day after docetaxel), promethazine 25 mg intramuscularly and cimetidine 600 mg ivi 30 min before docetaxel.

No significant financial relationships to disclose.

Phase II study of weekly docetaxel plus cisplatin as first-line therapy in advanced or metastatic non-small cell lung cancer (CHN TAX-206)

18173

Background: There has been increasing interest in the use of weekly administration of docetaxel as a way of reducing its hemotologic toxicity. Weekly docetaxel plus cisplatin has also shown promising efficacy and well tolerability for first-line treatment of advanced or metastatic NSCLC in our previous phase I study (2002 ASCO, abstract No 2744). We conducted this phase II trial to further evaluate this regimen’s efficacy and toxicity. Methods: Patients with histologically confirmed stage IIIB or IV NSCLC were treated with docetaxel (35 mg/m2, 30 min. iv. infusion) on days 1, 8, 15 and cisplatin (75 mg/m2, 30 min. iv. infusion) on day 1 repeated every 4 weeks for up to 6 cycles. Pts received oral dexamethasone 7.5 mg twice daily from the day before chemotherapy and consecutive two days thereafter. The primary endpoint of this phase II study is efficacy of the regimen. Results: A total of 83 patients were enrolled from July 2002 to June 2004, 75 patients were evaluable for response and 83 for safety. Median age was 55 years (range 29–70 years); and 69.9% were male; adenocarcinoma/squamous cell carcinoma/others (65/12/6); stage IIIB /IV( 47/36); ECOG PS 0/1(52/31). Median number of chemotherapy cycles was 3(1–5). One CR (complete response) and 22 PR (partial response) were achieved with an ORR of 30.7% in the evaluable patients. The 1-year survival was 48.6% with a median survival of 10.7 months (range: 3–34 months). Neutropenia was the most common adverse event, though most were mild; Grade III/IV toxicities per patient were: Neutropenia (15.6%), asthenia (11%), skin/nail toxicity (10.8%) and vomiting (9.6%). Febrile neutropenia was not observed. Conclusions: In the present study, the combination of weekly administration docetaxel combining with cisplatin appears well tolerated with very low frequency of severe hematologic toxicity and similarly efficacious as 3-weekly docetaxel in NSCLC pts.

No significant financial relationships to disclose.

Association of the 54-nucleotide repeat polymorphism of hPer3 with heroin dependence in Han Chinese population

Circadian clock genes have the function of producing circadian rhythm. They are also implicated in the origin or development of many diseases such as cancers and neuropsychiatric diseases. The purpose of this study is to determine whether the 54-nucleotide repeat polymorphism of hPer3, one of the circadian clock genes, associates with heroin dependence. DNA samples were obtained from 209 Chinese heroin-dependent subjects and 249 Chinese healthy controls. The 54-nucleotide repeat polymorphism was detected by polymerase chain reaction and DNA agarose gel electrophoresis. The frequency of four-repeat allele was significantly higher (chi(2)= 10.64, P = 0.001; corrected for multiple tests, P = 0.003) in the mixed gender heroin-dependent subject group (four repeat: 0.89, five repeat: 0.11) than in the mixed gender control group (four repeat: 0.81, five repeat: 0.19); the frequency of four-repeat allele was also significantly higher (chi(2)= 10.00, P = 0.002; corrected for multiple tests, P = 0.006) in the male heroin-dependent subject group (four repeat: 0.89, five repeat: 0.11) than in the male control group (four repeat: 0.81, five repeat: 0.19); for females, no significant trend was observed with the 54-nucleotide repeat polymorphism between the heroin-dependent subject group and the control group. Our results suggest that the 54-nucleotide repeat polymorphism of hPer3 significantly associates with heroin dependence at the allele frequency level and may be a potential risk factor for the development of heroin dependence.

Magnetic resonance elastography of brain tumors: preliminary results

PURPOSE

To investigate the potential value of magnetic resonance elastography (MRE) in evaluating the consistency of brain tumors.

MATERIAL AND METHODS

Six patients with known solid brain tumor underwent brain MRE studies. Consistency of brain tumors was evaluated at surgery. Correspondence of MRE evaluation with operative result was studied.

RESULTS

The elasticity of tumors in six patients evaluated by MRE agreed with the tumor consistency given by the operative results.

CONCLUSION

MRE could be used as an imaging technique for noninvasive assessment of the consistency of brain tumor in vivo.

Magnetic resonance elastography of the human brain: a preliminary study

PURPOSE

To study the application of magnetic resonance elastography (MRE) in the human brain.

MATERIAL AND METHODS

An external force actuator was developed, which produced propagating shear waves in brain tissue. A modified phase-contrast gradient-echo sequence was developed. The propagating shear waves within the brain were directly imaged. The wave images were processed to obtain the elasticity image. Shear waves at 100 Hz, 150 Hz, and 200 Hz were applied.

RESULTS

The propagating shear waves in the brain were visualized on wave images. The elasticity image revealed the difference in tissue elasticity between gray and white matter of the brain.

CONCLUSION

MRE could be an imaging technique for assessing the elasticity of brain tissue.

c-Jun N-terminal kinase mediates hydrogen peroxide-induced cell death via sustained poly(ADP-ribose) polymerase-1 activation

Reactive oxygen species (ROS) have been closely associated with both apoptotic and non-apoptotic/necrotic cell death. Our previous study has illustrated that c-Jun-N-terminal kinase 1 (JNK1) is the main executor in hydrogen peroxide (H(2)O(2))-induced nonapoptotic cell death. The main objective of this study is to further elucidate the molecular mechanisms downstream of JNK1 in H(2)O(2)-induced cell death. In this study, poly(ADP-ribose) polymerase-1 (PARP-1), a key DNA repair protein, was readily activated by H(2)O(2) and inhibition of PARP-1 activation by either a pharmacological or genetic approach offered significant protection against H(2)O(2)-induced cell death. More importantly, H(2)O(2)-mediated PARP-1 activation is subject to regulation by JNK1. Suppression of JNK1 activation by a chemical inhibitor or genetic deletion markedly suppressed the late-phase PARP-1 activation induced by H(2)O(2), suggesting that JNK1 contributes to the sustained activation of PARP-1. Such findings were supported by the temporal pattern of nuclear translocation of activated JNK and a direct protein-protein interaction between JNK1 and PARP-1 in H(2)O(2)-treated cells. Finally, in vitro kinase assay suggests that PARP-1 may serve as the direct phosphorylation target for JNK1. Taken together, data from our study reveal a novel underlying mechanism in H(2)O(2)-induced nonapoptotic cell death: JNK1 promotes a sustained PARP-1 activation via nuclear translocation, protein-protein interaction and PARP-1 phosphorylation.

Odontogenic tumours: a retrospective study of 1642 cases in a Chinese population

A total of 1642 odontogenic tumour cases retrieved from the files of the College of Stomatology, Sichuan University, China were retrospectively analyzed for gender, age, tumour site and relative frequency of various types, and the data compared with that of previous reports. The final diagnosis in each case was based on the WHO 2005 histopathological classification of odontogenic tumours. Of these tumours 1592 (97.0%) were benign and 50 (3.0%) were malignant. Ameloblastoma (40.3%) was the most frequent type, followed by keratocystic odontogenic tumour (35.8%), odontoma (4.7%) and odontogenic myxoma (4.6%). The mean age of the patients was 32.1, with a wide range (3-84 years). The male-female ratio and maxilla-mandible ratio were 1.4:1 and 1:4.0, respectively. Ameloblastoma and keratocystic odontogenic tumours, important indications of extensive surgical procedures, are not considered rare in this Chinese population, whereas odontoma is uncommon.