Robust MR assessment of cerebral blood volume and mean vessel size using SPION-enhanced ultrashort echo acquisition

Intravascular superparamagnetic iron oxide nanoparticles (SPION)-enhanced MR transverse relaxation rates (∆R2(⁎) and ∆R2) are widely used to investigate in vivo vascular parameters, such as the cerebral blood volume (CBV), microvascular volume (MVV), and mean vessel size index (mVSI, ∆R2(⁎)/∆R2). Although highly efficient, regional comparison of vascular parameters acquired using gradient-echo based ∆R2(⁎) is hampered by its high sensitivity to magnetic field perturbations arising from air-tissue interfaces and large vessels. To minimize such demerits, we took advantage of the dual contrast property of SPION and both theoretically and experimentally verified the direct benefit of replacing gradient-echo based ∆R2(⁎) measurement with ultra-short echo time (UTE)-based ∆R1 contrast to generate the robust CBV and mVSI maps. The UTE acquisition minimized the local measurement errors from susceptibility perturbations and enabled dose-independent CBV measurement using the vessel/tissue ∆R1 ratio, while independent spin-echo acquisition enabled simultaneous ∆R2 measurement and mVSI calculation of the cortex, cerebellum, and olfactory bulb, which are animal brain regions typified by significant susceptibility-associated measurement errors.

In vivo imaging of Lgr5-positive cell populations using confocal laser endomicroscopy during early colon tumorigenesis

BACKGROUND AND STUDY AIMS

A diagnostic molecular marker for pre-neoplastic lesions, particularly before polyposis, is still lacking. Lgr5 has been broadly accepted as a marker for intestinal cancer stem cells. The aim of this study was to investigate the monitoring of Lgr5( + ) cells as a useful tool for the early diagnosis of premalignant lesions before polyp formation.

METHODS

In vivo molecular imaging was performed to examine colon tumorigenesis in Lgr5-EGFP mice treated with azoxymethane and dextran sodium sulfate. eGFP( +) Lgr5( +) regions in the descending colon were longitudinally monitored using side-view confocal endomicroscopy. Based on the eGFP signal intensity on the luminal surface, polyps were classified into two groups - Lgr5-high and Lgr5-low. White light colonoscopy was used to monitor polyp formation.

RESULTS

Approximately 75 % of the polyps originated from foci containing Lgr5-eGFP( +) cells, whereas 25 % of the polyps emerged from Lgr5( -) foci. Among eGFP( +) foci, Lgr5-high foci grew faster than Lgr5-low foci.

CONCLUSIONS

Polyps developed at Lgr5( +) regions. Luminal Lgr5 expression was correlated with the growth rate of early-stage adenomas. Lgr5 is a promising molecular marker for the early diagnosis of colon tumors.

Ultrafast 3D spin-echo acquisition improves Gadolinium-enhanced MRI signal contrast enhancement

Long scan times of 3D volumetric MR acquisitions usually necessitate ultrafast in vivo gradient-echo acquisitions, which are intrinsically susceptible to magnetic field inhomogeneities. This is especially problematic for contrast-enhanced (CE)-MRI applications, where non-negligible T₂* effect of contrast agent deteriorates the positive signal contrast and limits the available range of MR acquisition parameters and injection doses. To overcome these shortcomings without degrading temporal resolution, ultrafast spin-echo acquisitions were implemented. Specifically, a multiplicative acceleration factor from multiple spin echoes (×32) and compressed sensing (CS) sampling (×8) allowed highly-accelerated 3D Multiple-Modulation-Multiple-Echo (MMME) acquisition. At the same time, the CE-MRI of kidney with Gd-DOTA showed significantly improved signal enhancement for CS-MMME acquisitions (×7) over that of corresponding FLASH acquisitions (×2). Increased positive contrast enhancement and highly accelerated acquisition of extended volume with reduced RF irradiations will be beneficial for oncological and nephrological applications, in which the accurate in vivo 3D quantification of contrast agent concentration is necessary with high temporal resolution.

The comparison of femoral and radial arterial blood pressures during pediatric liver transplantation

BACKGROUND

Orthotopic liver transplantation (OLT) is frequently associated with dramatic hemodynamic changes; thus, it is critical to accurately monitor blood pressure. Although comparisons between femoral arterial blood pressure (FABP) and radial arterial blood pressure (RABP) have been reported in adult liver recipients, we compared FABP with RABP in pediatric recipients.

METHODS

Thirty-five pediatric liver recipients younger than 13 years of age were included in this prospective, observational study. We measured simultaneous FABP and RABP in the femoral and radial arteries at nine time points during the procedure, including: baseline (after anesthetic induction); 1 hour thereafter; 30 minutes after the beginning of the anhepatic period as well as 0, 1, 3, 5, 15, and 60 minutes after graft reperfusion.

RESULTS

Of the 35 pediatric liver recipients, 2 infants and 1 13-month-old child were excluded from the analysis because of radial arterial catheter malfunction. The remaining 32 patients including 16 infants and 16 children all showed significantly higher systolic and mean FABP than RABP during most stages of pediatric OLT. Overall diastolic FABP measurements were similar to diastolic RABP throughout the study.

CONCLUSIONS

Systolic and mean FABP were significantly higher than RABP during most stages of pediatric OLT. Radial arterial catheter malfunctions were not uncommon during pediatric OLT. Our results indicated that it is useful to cannulate the femoral artery to accurately and reliably measure arterial blood pressure to detect hemodynamic instability during pediatric OLT.

The effects of prolonged inspiratory time during one-lung ventilation: a randomised controlled trial

We evaluated the effects of a prolonged inspiratory time on gas exchange in subjects undergoing one-lung ventilation for thoracic surgery. One hundred patients were randomly assigned to Group I:E = 1:2 or Group I:E = 1:1. Arterial blood gas analysis and respiratory mechanics measurements were performed 10 min after anaesthesia induction, 30 and 60 min after initiation of one-lung ventilation, and 15 min after restoration of conventional two-lung ventilation. The mean (SD) ratio of the partial pressure of arterial oxygen to fraction of inspired oxygen after 60 min of one-lung ventilation was significantly lower in Group I:E = 1:2 compared with Group I:E = 1:1 (27.7 (13.2) kPa vs 35.2 (22.1) kPa, respectively, p = 0.043). Mean (SD) physiological dead space-to-tidal volume ratio after 60 min of one-lung ventilation was significantly higher in Group I:E = 1:2 compared with Group I:E = 1:1 (0.46 (0.04) vs 0.43 (0.04), respectively, p = 0.008). Median (IQR [range]) peak inspiratory pressure was higher in Group I:E = 1:2 compared with Group I:E = 1:1 after 60 min of one-lung ventilation (23 (22-25 [18-29]) cmH2O vs 20 (18-21 [16-27]) cmH2O, respectively, p < 0.001) and median (IQR [range]) mean airway pressure was lower in Group I:E = 1:2 compared with Group I:E = 1:1 (10 (8-11 [5-15]) cmH2O vs 11 (10-13 [5-16]) cmH2O, respectively, p < 0.001). We conclude that, compared with an I:E ratio of 1:2, an I:E ratio of 1:1 resulted in a modest improvement in oxygenation and decreased shunt fraction during one-lung ventilation.

Bioimaging of hyaluronic acid derivatives using nanosized carbon dots

Fluorescent nanosized carbon dots (Cdots) are an emerging bioimaging agent with excellent chemical inertness and marginal cytotoxicity in comparison to widely used semiconductor quantum dots. In this work, we report the application of Cdots for real time bioimaging of target specific delivery of hyaluronic acid (HA) derivatives. Polyethylene glycol (PEG) diamine-capped Cdots were synthesized by the pyrolysis of citric acid in a hot solvent. The synthesized Cdots showed strong fluorescence under UV excitation with emission properties dependending on the excitation wavelength. HA-Cdot conjugates were synthesized by amide bond formation between amine groups of Cdot and carboxylic groups of HA. After confirmation of the negligible cytotoxicity of Cdots and HA-Cdot conjugates, in vitro bioimaging was carried out for target specific intracellular delivery of the HA-Cdot conjugates by HA receptor-mediated endocytosis. Furthermore, in vivo real-time bioimaging of Cdots and HA-Cdot conjugates exhibited the target specific delivery of HA-Cdot conjugates to the liver with abundant HA receptors. Taken together, we could confirm the feasibility of HA derivatives as a target-specific drug delivery carrier for the treatment of liver diseases and Cdots as a promising bioimaging agent.

Patterns of pncA mutations in drug-resistant Mycobacterium tuberculosis isolated from patients in South Korea

BACKGROUND

Pyrazinamide (PZA), one of the most effective anti-tuberculosis drugs, becomes toxic to Mycobacterium tuberculosis when converted to pyrazinoic acid by pyrazinamidase (PZase). PZA resistance is caused mainly by the loss of enzyme activity by mutation.

OBJECTIVE

To investigate the patterns of pncA mutations in PZA-resistant mycobacteria isolated from South Korean patients.

METHODS

Mycobacterial isolates with clinically proven drug resistance were cultured to determine susceptibility to anti-tuberculosis agents. pncA mutations were recognised by sequencing and compared with the relevant wild-type DNA sequence.

RESULTS

Among 108 isolates, 102 were successfully cultured and underwent drug susceptibility testing; all were multidrug-resistant (MDR). pncA mutations were found in 86 cultured isolates (85.1%): 55 (84.6%) in MDR and 31 (86.1%) in extensively drug-resistant isolates. Substitution of a single nucleotide was most common. The most frequent mutations were a deletion that caused a frameshift at nucleotide (nt) 71, a substitution at nt 403 and a substitution at nt 11. Combined, these accounted for ≈ 40% of all mutations. However, 15 samples (14.9%) with defective PZase activity showed no mutation.

CONCLUSION

pncA mutation in M. tuberculosis is a major mechanism of PZA resistance in MDR isolates from patients in South Korea. The patterns of mutation might be more scattered and diverse. DNA-based diagnosis of PZA resistance has potential for the rapid detection of drug resistance.

Elevated levels of macrophage migration inhibitory factor in women with metabolic syndrome

Metabolic syndrome is a complex clinical disorder characterized by obesity, a disturbance of glucose metabolism, dyslipidemia, and hypertension, leading to increased cardiovascular risk. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine produced both by innate immune cells and by adipocytes, and it plays an important role in inflammatory and cardiovascular diseases. The goal of this study was to evaluate the expression of circulating MIF in patients with metabolic syndrome. A study was conducted involving 172 persons who attended the Jeju National University Hospital Health Promotion Center. Among the 172 subjects, 88 patients with metabolic syndrome and 84 healthy control subjects were included. Serum MIF levels were considerably higher in patients with metabolic syndrome than in healthy subjects (mean±SEM, 1413.0-pg/ml±102.6 vs. 1077.0-pg/ml±-91.3, p=0.016). Among the metabolic syndrome patients, MIF levels were significantly increased in women (1403.0-pg/ml±114.2 vs. 921.3 pg/ml±117.3, p=0.005), but not in men. Even after further linear regression adjustment for age and body mass index, the expression of MIF for women with metabolic syndrome was still clearly elevated when compared to healthy subjects (p=0.011). Circulating MIF concentrations showed a gender disparity between healthy and metabolic syndrome subjects. An elevation of systemic MIF in women with metabolic syndrome may contribute to pathogenesis of metabolic syndrome or to the development of metabolic syndrome-related diseases, such as atherosclerosis and type 2 diabetes mellitus.

Detection of antigenic proteins expressed by lymphocystis virus as vaccine candidates in olive flounder, Paralichthys olivaceus (Temminck & Schlegel)

Although the major capsid proteins (MCPs) of lymphocystis disease virus (LCDV) have been characterized, little is known about the host-derived immune response to MCPs and other LCDV antigenic proteins. To identify antigenic proteins of LCDV that could be used as vaccine candidates in olive flounder, Paralichthys olivaceus, we analysed the viral proteins responsible for its virulence by applying immuno-proteomics. LCDV proteins were separated by one-dimensional gel electrophoresis, transferred to polyvinylidene difluoride membrane, and probed with homogeneous P. olivaceus antisera elicited by LCDV natural infection and vaccination with formalin-killed LCDV. Four immune-reactive proteins were obtained at 68-, 51-, 41- and 21 kDa using antisera collected from natural infection while two proteins at 51- and 21 kDa exhibited response to antisera from vaccinated fish, indicating that the latter two proteins have vaccine potential. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nanoelectrospray MS/MS, the 51 and 21 kDa proteins were identified as MCP and an unknown protein, respectively.

Peroral direct cholangioscopic-guided biopsy and photodynamic therapy using an ultraslim upper endoscope for recurrent hepatocellular carcinoma with intraductal tiny nodular tumor growth

Bile-duct invasion is rare in patients with hepatocellular carcinoma (HCC). We report a case that received peroral direct cholangioscopy (PDCS)-guided endoscopic biopsy and photodynamic treatment (PDT) for recurrent HCC with intraductal tiny nodular tumor growth. A 64-year-old woman presented with recurrent right upper-quadrant pain. Six months previously she had been diagnosed with HCC with bile-duct invasion in the right anterior segment and had received right anterior segmentectomy. On pathological examination, the margin of resection was clear, but macroscopic bile-duct invasion was noted. On admission, magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography (ERCP) revealed a 0.5-cm-sized polypoid mass at the hilar portion. ERCP-guided biopsy failed, and an ampullary stricture was noted. PDCS-guided endoscopic biopsy was thus performed, and histopathology of the retrieved specimen revealed HCC. The patient submitted to PDT. There was no procedure-related complication. After 1 month of PDT the polypoid lesion and scar change at the hilar lesion had disappeared.

EUS-guided drainage of hepatic abscesses not accessible to percutaneous drainage (with videos)

BACKGROUND

Currently, percutaneous drainage is the first treatment of choice for hepatic abscesses because of its high success and low mortality rates compared with other surgical procedures. However, percutaneous drainage of hepatic abscesses in the caudate lobe or gastrohepatic space may be difficult.

OBJECTIVE

The aim of this study was to determine the technical feasibility and clinical implication of EUS-guided drainage for hepatic abscesses not accessible to percutaneous biliary drainage.

DESIGN

Single-center prospective case series.

SETTING

Academic tertiary referral center.

PATIENTS

This study involved 3 consecutive patients with hepatic abscesses not accessible to percutaneous biliary drainage: 2 in the caudate lobe and 1 in the gastrohepatic extension from the posteromedial aspect of the lateral segment.

INTERVENTIONS

EUS-guided drainage with a plastic stent and/or nasocystic tube was conducted using a therapeutic linear-array echoendoscope under endoscopic and fluoroscopic guidance.

RESULTS

The EUS-guided transgastric approach was performed in 2 patients (1 in the caudate lobe, and 1 in the gastrohepatic space). In the other patient (caudate lobe), EUS-guided transduodenal drainage was conducted. EUS-guided drainage with the placement of a plastic stent and/or nasocystic tube was successful in all of the patients. Complete resolution of the hepatic abscesses and symptom relief were achieved in all of the patients (3 out of 3, 100%). No procedural complications were observed. Follow-up results were also favorable.

LIMITATIONS

Small series of cases.

CONCLUSIONS

For this case series, EUS-guided drainage of hepatic abscesses not accessible to percutaneous drainage, such as those in the caudate lobe or gastrohepatic space, is technically feasible, safe, and provides complete drainage, symptom relief, and favorable follow-up results.

Sunitinib, a novel therapy for anthracycline- and cisplatin-refractory malignant pheochromocytoma

We report a case of malignant pheochromocytoma recurred after debulking surgery. A 17-year-old male patient visited our hospital for right flank pain. He had not experienced palpitations, headache, sweating or weight loss. Level of urinary catecholamine and its metabolite increased above normal values and abdominal computed tomography showed a huge right adrenal mass. One month after debulking surgery, anterior mediastinal and multiple liver metastases were found. These tumors had no response to two conventional regimens of combination chemotherapy (cyclophosphamide, vincristine, dacarbazine and anthracycline; and etoposide and cisplatin). We treated the patient with sunitinib, a multiple tyrosine kinase inhibitor. The tumor showed very good metabolic response to the therapy. In patient with malignant pheochromocytoma, sunitinib might be one therapeutic strategy for malignant pheochromocytomas.

In vivo quantification of transvascular water exchange during the acute phase of permanent stroke

Mechanisms that underlie early ischemic damages to the blood-brain-barrier (BBB) are not well understood. This study presents a novel magnetic resonance imaging (MRI) technique using a widely available pulse sequence and a long-circulating intravascular contrast agent to quantify water movements across the BBB at early stages of stroke progression. We characterized the integrity of the BBB by measuring the flip angle dependence of the water exchange-affected MRI signal intensity, to generate an efficient quantitative index of vascular permeability (WEI, or water exchange index). We performed in vivo MRI experiments to measure the transvascular WEI immediately after the permanent filament occlusion of the middle cerebral artery of mice (n = 5), in which we monitored changes in blood volume (V(b)), apparent diffusion coefficient (ADC), and intra-/extravascular WEI for 4 hours. Statistically significant elevations (P < 0.05) of WEI in the ischemic tissue were observed as early as 1 hour after ischemic onset. Initial reduction of the apparent blood volume (V(app)) in the infarct cortex was followed by a continuous increase of V(app) over time. Although the measured ADC in the ipsilesional cortex continuously decreased, the abnormally high intra-/extravascular WEI remained constant at a significantly elevated level, indicating apparent BBB injury at this early stage of stroke.

Infectious complications in living-donor liver transplant recipients: a 9-year single-center experience

BACKGROUND

Infectious complications following living-donor liver transplantation (LDLT) remain a major cause of morbidity and mortality. We analyzed the frequency and type of infectious complications according to the post-transplantation period, and their risk factors with regard to morbidity and mortality.

METHODS

We retrospectively analyzed 208 subjects who had undergone LDLT during a 9-year period.

RESULTS

The rate of infection was 1.69 per patient during the study period. The predominant infections were intra-abdominal infections (37.6%), primary bacteremia (17.4%), and pneumonia (14.5%). Within the first post-transplant month, 140 (39.9%) infections were detected, and catheter-related coagulase-negative staphylococci (44) were the most common infectious agents. During the 2-6-month post-transplant period, 109 infectious episodes occurred (31.1%), and Enterococcus sp. (n=16) related to biliary infection was the most frequent isolate. After the sixth month, 96 infectious episodes (29%) occurred, and biliary tract-related Escherichia coli (n=19) was the major causative organism. The overall mortality was 24.5% (51/208); 1-year survival rate was 88% (196/208). Post-transplant infection-related mortality was 52.9% (27/51). Biliary tract complications, such as biliary stenosis or leakage, significantly increased the mortality (P=0.01); however, reoperation (retransplantation or resurgery for biliary tract obstruction/leakage or to control bleeding) significantly reduced the mortality (P=0.01).

CONCLUSIONS

Our data showed that early catheter removal would mainly aid in reducing infectious complications in the 1-month post-transplantation period. Aggressive management, including reoperation, would lower the mortality in the LDLT recipients.

Immunoproteomic analysis of capsulate and non-capsulate strains of Lactococcus garvieae

A comparative immunoproteomic study was carried out to investigate the immunogenicity of capsulate (KG9408) and non-capsulate (NSS9310) strains of Lactococcus garvieae. Immunoblot assays, following two-dimensional gel electrophoresis (2-DE) for L. garvieae strains, revealed a significant difference between anti-capsulate and anti-non-capsulate rabbit sera with respect to the number and antigenicity of antigenic spots. Anti-capsulate and anti-non-capsulate rabbit sera reacted with an average of 72 and 127 antigenic spots, respectively. The strong reaction of anti-non-capsulate sera with elongation factor (EF)-G and -Tu, and GMP synthase, of the L. garvieae strains identifies these as specific major antigens. This study clearly demonstrates the differences in 2-DE immunoblot profiles between the capsulate and non-capsulate strains of L. garvieae. These differences may be the reason for variations in immunogenicity between capsulate and non-capsulate strains. Glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, arginine deaminase and ornithine carbamoyltransferase were identified from the 2-DE immunoblot profiles of both strains. Therefore, these common antigens are potential markers for the development of vaccines against L. garvieae, irrespective of strain. Immunoproteomics, a powerful tool for studying antigens at the proteomic level, allowed a comparative investigation of the immunogenicity of capsulate and non-capsulate strains of L. garvieae for vaccine development.

Therapeutic use of granulocyte-colony stimulating factor could conceal residual malignant cells in patients with AML1/ETO+ acute myelogenous leukemia

We have experienced a number of cases of AML1/ETO+ acute myelogenous leukemia that showed remission based on bone marrow (BM) morphological criteria, but that revealed clonal abnormalities in most cells by fluorescence in situ hybridization (FISH). Interestingly, most of these cases had AML with AML1/ETO rearrangement. The malignant cells were differentiated and considered mature cells after granulocyte-colony stimulating factor (G-CSF) treatment. To clarify the possible mechanisms underlying this phenomenon, we investigated the expression levels of G-CSFR in AML cells with AML1/ETO rearrangement by flow cytometry and real-time polymerase chain reaction (PCR). The number of AML1/ETO+ cells expressing G-CSFR at baseline was significantly higher than that of AML1/ETO- AML cells (2673 vs 522). In addition, the G-CSFR gene was more highly expressed in AML1/ETO+ cells than in AML1/ETO- cells by real-time PCR. This study reveals that cases showing remission after treatment with G-CSF mostly had leukemia with AML1/ETO rearrangement. This finding might be explained by the higher expression of G-CSF receptor in AML1/ETO+ cells than in AML1/ETO- cells. We recommend that remission should be confirmed by FISH, because malignant clones can be differentiated and masked in morphological examination or chromosome test, especially for AML with AML1/ETO rearrangement.

Protein 4.1 deficiency and deletion of chromosome 20q are associated with acquired elliptocytosis in myelodysplastic syndrome

We report a case of myelodysplastic syndrome (MDS), associated with prominent elliptocytosis. A 66-year-old male presented with peripheral pancytopenia, and was diagnosed with MDS [refractory anaemia (RA)]. Apart from marked elliptocytosis, dyshaematopoietic features were not evident in his peripheral blood or hypercellular bone marrow. After 18 months, he had progressed to RA with excess blasts in transformation. Analysis of red blood cell membrane proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a reduced quantity of protein 4.1 (30% of control). Deletion of chromosome 20q was identified by conventional cytogenetic analysis and fluorescence in situ hybridization. Marked elliptocytosis, persistent for more than 17 months, decreased strikingly after chemotherapy with idarubicin and Ara-C. These findings suggest that acquired elliptocytosis occurred as an unusual morphological feature of MDS, associated with abnormalities of protein 4.1 and chromosome 20q.

Measurement of tumor interstitial volume fraction: Method and implication for drug delivery

It is important to evaluate the tumor interstitial volume fraction that is accessible for drug accumulation during the distribution phase in order to determine the potential efficacy of cancer chemotherapy. In this study, we performed simulations of magnetic resonance imaging (MRI) signal intensity using a two-compartment tissue model for quantitative analyses of absolute interstitial volume measurements while we experimentally characterized a mouse tumor model with a dual MR contrast-agent method. Previously, consecutive intravenous injections of a strictly intravascular T1 contrast agent followed by an extravasating agent were used as a strategy for the quantification of both relative blood volume (Rel_BV) and relative interstitial volume (Rel_ITST) (Weissleder et al. Eur J Cancer 1998;34:1448-1454; Bogdanov et al. Neoplasia 1991;1:438-435). In the current study, we demonstrate that this approach can be further improved, and that it enables one to accurately evaluate both relative and absolute interstitial volumes. The animal data indicated that a significant difference exists between the absolute interstitial volume fractions of subcutaneously implanted MDA PCa 2b tumor and skeletal muscle tissue (27.5 +/- 9.1% and 15.9 +/- 0.7%, respectively (P < 0.05)), while only a minor difference was found for the absolute blood volumes (Abs_BV) (Kim et al. Magn Reson Med 2002;47:1110-1120) of these tissues.

Water exchange and inflow affect the accuracy of T1-GRE blood volume measurements: implications for the evaluation of tumor angiogenesis

The goal of this study was to determine the degree to which vascular water exchange and blood flowing into an imaging slice affect the accuracy of blood volume measurements of brain and tumor tissue when using intravascular T(1) contrast agents. The study was performed using 2D and 3D gradient-echo imaging sequences, since these are two of the most commonly used MRI methods used to evaluate tissue blood volume fraction. Computer simulations were performed and measurements made in a rat 9L gliosarcoma brain tumor model. The computer simulations demonstrate that, with either water exchange or inflow effects alone, the dependence on the physiologic and imaging parameters can be well characterized and therefore potentially offset. In the exchange only case, the parametric dependence of 3D simulations suggest that the best accuracy is achieved with high flip angles, short TR, and low blood contrast agent concentrations. However, for a 2D GRE sequence which is influenced by both water exchange and inflow, the simulations predict that the error trend as a function of the imaging and physiologic parameters is unpredictable and therefore difficult to compensate. With both 2D and 3D GRE the measured blood volume data in rat brain and tumor tissue demonstrate tissue-specific trends, which reflect differences in the considered physiologic parameters. The experimental data strongly support the computer simulations and also indicate that minimization of the physiological effects by proper selection of imaging parameters, contrast concentration, and volume calculation methods is crucial for accurate assessment of absolute blood volume fraction.

Polymorphisms of the CTLA-4 exon 1 and promoter gene in systemic lupus erythematosus

The objective of this study was to determine whether the polymorphisms of the CTLA-4 exon 1 (+49) and promoter (-318) are associated with susceptibility to systemic lupus erythematosus (SLE) and its clinical features. Polymerase chain reaction of genomic DNA-restriction fragment length polymorphism was used to determine genotypes of the CTLA-4 exon 1 (+49) and promoter (-318) in 80 SLE patients and 86 healthy control subjects. The genotype distribution of the CTLA-4 exon 1 (+49) differed between SLE patients and controls (chi2 = 6.74, 2 degrees of freedom (d.f.), P = 0.03). The CTLA-4 AG genotype occurred more frequently in patients with SLE (46.3% vs 33.7% controls). On the other hand, the CTLA-4 AA genotype as well as the CTLA-4 GG genotype was less frequent among SLE patients than among control subjects (1.3% vs 9.3% and 52.5% vs 57.0%, respectively). The genotype distribution of the CTLA-4 promoter (-318) differed between SLE patients and control subjects (CT, TT, CC; genotypes 27.5%, 0%, 72.5% vs 16.3%, 4.7%, 79.1% controls respectively, chi2 = 6.36, 2 d.f., P = 0.04). However, Fischer's exact or chi2 P-values for each genotypes of the CTLA-4 exon 1 (+49) and promoter (-318) between SLE and control group were > 0.05. Clinically, in the lupus patients there was no significant difference according to the CTLA-4 polymorphisms. In conclusion, no correlation was found between CTLA-4 exon 1 (+49) and promoter (-318) polymorphisms and SLE in our study.

Genetic variations of cholesterol ester transfer protein gene in Koreans

An absence of cholesterol ester transfer protein (CETP, protein; CETP, gene) results in an increase of the apolipoprotein AI levels and a decrease in the low density lipoprotein (LDL) levels. Thus, the CETP polymorphism is important in the assessment of risk of atherosclerosis. This study was conducted to elucidate the genotype distributions of the CETP polymorphism and association with plasma lipid levels in Koreans. The genotypes of the TaqI A and B polymorphic loci were associated with plasma triglyceride levels in the control and coronary artery disease (CAD) groups. There was linkage disequilibrium between TaqI A and B loci in the control group (chi2 = 5.58, p < 0.05). Association studies of the CETP polymorphism have been carried out mainly with Caucasian populations; however, the results have not been consistent among different populations. A possible explanation for this diversity among populations may be differences in genetic backgrounds, which may be more important than environmental factors. We discuss the reasons for the incompatibility of the CETP polymorphism among populations.

Folding and stability of sweet protein single-chain monellin. An insight to protein engineering

Engineered single-chain monellin (SCM) proteins were constructed by recombinant technology without disrupting the topology and sweet activity of native protein. Data from 8-anilinonaphthalene-1-sulfonic acid fluorescence, size-exclusion chromatography, and heteronuclear NMR strongly suggest the presence of a folding intermediate at 1.5 m GdnHCl for SCM protein. The structural feature of the folding intermediate from NMR data reveals that the secondary structures became mostly unstable, and protein experiences a dynamic equilibrium between native and unfolded state. All backbone amide protons exchange within 10 min, which imply that no stable hydrogen bonds exist in the secondary structural regions in the folding intermediate. From equilibrium unfolding and mutagenesis studies, the unfolding transition midpoints of mutant proteins gradually shifted toward lower denaturant concentration, indicating stability reductions of mutant proteins. Our results suggest that stability and folding pathways of SCM proteins could be regulated by a combined study of spectroscopy and mutagenesis, and these studies will provide useful information for understanding the folding kinetics of novel engineered proteins.