Growth of Ultrathin Films of Amorphous Ruthenium−Phosphorus Alloys Using a Single Source CVD Precursor

Thin films ( approximately 30 nm) of amorphous RuP alloys (P approximately 15-20%) can be grown by CVD from the single source precursor cis-H2Ru(PMe3)4 at 250-300 degrees C and 200 mTorr pressure on native SiO2.

MR urography in children

MR urography represents the next step in the evolution of uroradiology in children by combining superb anatomic imaging with quantitative functional evaluation in a single examination that does not use ionizing radiation. MR imaging has inherently greater soft-tissue contrast than other imaging techniques. When used in conjunction with dynamic scanning after administration of a contrast agent, it provides non-invasive analysis of the perfusion, concentration and excretion of each kidney. The purpose of this review is to outline our experience with more than 500 MR urograms in children. We outline our technique in detail, showing how we calculate differential renal function and how we assess concentration and excretion in the different regions of the kidney. We show that the dynamic contrast-enhanced data can be processed to yield quantitative measures of individual kidney GFR. In the clinical section we show how MR urography adds unique aspects to the anatomic evaluation of the urinary tract, and by combining the anatomic information with functional information, how we assess hydronephrosis and obstructive uropathy, congenital malformations, pyelonephritis and renal scarring.

Reactive oxygen species and erectile dysfunction: possible role of NADPH oxidase

Erectile dysfunction (ED) is a widespread condition, the incidence of which is increasing globally. ED is also indicative of underlying vasculopathy and represents a predictor of more serious cardiovascular disorders. Understanding the aetiology of ED may therefore provide invaluable pointers to the pathobiology of other cardiovascular diseases (CVDs) and syndromes. It follows, too, that therapeutic interventions that are successful in treating ED may, ipso facto, be effective in treating the early stages of conditions that include atherosclerosis, angina, plaque rupture and diabetic angiopathy. One common pathological denominator in both CVD and ED is oxidative stress, that is, the overproduction of reactive oxygen species (ROS), in particular, superoxide (O(2)(*-)) and hydrogen peroxide (H(2)O(2)). In this review, therefore, we consider the aetiology and pathobiology of O(2)(*-) in promoting ED and focus on NADPH oxidase as an inducible source of O(2)(*-) and H(2)O(2). Therapeutic strategies aimed at reducing oxidative stress to improve erectile function are also discussed.

Heterobimetallic Zn(II)−Ln(III) Phenylene-Bridged Schiff Base Complexes, Computational Studies, and Evidence for Singlet Energy Transfer as the Main Pathway in the Sensitization of Near-Infrared Nd3+ Luminescence

A series of 3d-4f heterobimetallic phenylene-bridged Schiff base complexes of the general formula [Zn(mu-L1)Ln(NO3)3(S)n] [Ln = La (1), Nd (2), Gd (3), Er (4), Yb (5); S = H(2)O, EtOH; n = 1, 2; H2L1 = N,N'-bis(3-methoxysalicylidene)phenylene-1,2-diamine] and [Zn(mu-L2)Ln(NO3)3(H2O)n] [Ln = La (6), Nd (7), Gd (8), Er (9), Yb (10); n = 1, 2; H(2)L(2) = N,N'-bis(3-methoxy-5-p-tolylsalicylidene)phenylene-1,2-diamine] were synthesized and characterized. Complexes 1, 2, 4, and 7 were structurally characterized by X-ray crystallography. At room temperature in CH(3)CN, both neodymium(III) (2 and 7) and ytterbium(III) (5 and 10) complexes also exhibited, in addition to the ligand-centered emission in the UV-vis region, their lanthanide(III) ion emission in the near-infrared (NIR) region. The photophysical properties of the zinc(II) phenylene-bridged complexes (ZnL1 and ZnL2) were measured and compared with those of the corresponding zinc(II) ethylene-bridged complexes (ZnL3 and ZnL4). Our results revealed that, at 77 K, both ligand-centered triplet (3LC) and singlet (1LC) states existed for the ethylene-bridged complexes (ZnL3 and ZnL4), whereas only the (1)LC state was detected for the phenylene-bridged complexes (ZnL1 and ZnL2). NIR sensitization studies of [Zn(mu-L')Nd(NO3)3(H2O)n] (L' = L1-L4) complexes further showed that Nd3+ sensitization took place via the 3LC and 1LC states when the spacer between the imine groups of the Schiff base ligand was an ethylene and a phenylene unit, respectively. Ab initio calculations show that the observed differences can be attributed to the difference in the molecular vibrational properties and electron densities of the electronic states between the ethylene- and phenylene-bridged complexes.

Magnetic resonance urography in the evaluation of prenatally diagnosed hydronephrosis and renal dysgenesis

PURPOSE

We present our experience with dynamic contrast enhanced magnetic resonance urography for evaluation and treatment in infants born with prenatally recognized hydronephrosis. We determined the characteristics of renal dysgenesis in this population.

MATERIALS AND METHODS

We reviewed magnetic resonance urography images done within the first 6 months of life in 67 infants born with prenatally recognized hydronephrosis. High resolution imaging was used to establish a morphological diagnosis. Functional evaluation was used to assess obstruction and individual renal function. Voiding cystourethrography was performed in 62 patients.

RESULTS

Our study included 67 infants (87 renal units). There were 54 boys and 13 girls with a mean age of 2.8 months (range 0.9 to 4.6). Of these 87 renal units 30 (35%) had ureteropelvic junction obstruction, 18 (21%) had primary megaureters, 10 (11%) had nondilating vesicoureteral reflux, 10 (11%) had fetal folds, 8 (9%) had posterior urethral valves, 6 (7%) had ectopic ureters, 4 (5%) had multicystic dysplastic kidneys and 1 (1%) had a normal study. Magnetic resonance urography revealed renal dysgenesis in 24 renal units (28%), consisting of loss of corticomedullary differentiation, renal cystic changes distinct from multicystic dysplastic kidneys, solid renal dysplasia, hypoplasia and dysmorphic calyces.

CONCLUSIONS

Magnetic resonance urography is an excellent addition to our armamentarium for evaluating neonatal hydronephrosis and renal dysgenesis. Due to its comprehensiveness magnetic resonance urography has the potential to become the study of choice for evaluating infants with significant prenatally recognized hydronephrosis. However, further prospective, comparative studies in larger patient populations are needed to justify the cost and the need for sedation in infants.

Magnetic resonance urography for evaluating outcomes after pediatric pyeloplasty

PURPOSE

We report the role of magnetic resonance urography in children with ureteropelvic junction obstruction. Differential renal function, the single kidney glomerular filtration rate index, renal transit time, renal length and renal pelvis anteroposterior diameter were compared before and after pyeloplasty.

MATERIALS AND METHODS

Magnetic resonance urography was performed before and after pyeloplasty in 24 patients with a mean age of 1.9 years (range 3 months to 10 years). Renal length, renal transit time and renal pelvis anteroposterior diameter were determined by the radiologist. The volume of functioning renal tissue and descending aorta were segmented and the ratio of the volumes of functioning kidney tissue was used to calculate differential renal function. Rutland-Patlak plots were used to calculate single kidney glomerular filtration rate index, that is the Patlak score.

RESULTS

Mean renal pelvis renal pelvis anteroposterior diameter was 3.3 cm preoperatively and 2.5 cm postoperatively (p = 0.0003). There was no difference in average renal length (p = 0.22). Of the 24 cases 22 (92%) showed stable or improved differential renal function. Improvement in renal transit time was seen in 20 of 23 cases (87%). Of 15 patients with complete Patlak scores 14 (93%) showed postoperative improvement. Mean preoperative and postoperative differential renal function, renal transit time and Patlak score were 36% and 41% (p = 0.003), 16.2 and 8.6 minutes (p = 0.0005), and 6.6 and 11.9 ml per minute (p = 0.01), respectively.

CONCLUSIONS

Magnetic resonance urography provides superior anatomical and unprecedented functional information to fully define the preoperatively and postoperative status of corrected ureteropelvic junction obstruction. Magnetic resonance urography has the potential to become the imaging study of choice for evaluating pediatric hydronephrosis and obstructive uropathy.

Transgenic overexpression of IGF-IR disrupts mammary ductal morphogenesis and induces tumor formation

Overexpression and hyperactivation of the type I insulin-like growth factor receptor (IGF-IR) has been observed in human breast tumor biopsies. In addition, in vitro studies indicate that overexpression of IGF-IR is sufficient to transform cells such as mouse embryo fibroblasts and this receptor promotes proliferation and survival in breast cancer cell lines. To fully understand the function of the IGF-IR in tumor initiation and progression, transgenic mice containing human IGF-IR under a doxycycline-inducible MMTV promoter system were generated. Administration of 2 mg/ml doxycycline in the animals' water supply beginning at 21 days of age resulted in elevated levels of IGF-IR in mammary epithelial cells as detected by Western blotting and immunohistochemistry. Whole mount analysis of 55-day-old mouse mammary glands revealed that IGF-IR overexpression significantly impaired ductal elongation. Moreover, histological analyses revealed multiple hyperplasic lesions in the mammary glands of these 55-day-old mice. The formation of palpable mammary tumors was evident at approximately 2 months of age and was associated with increased levels of IGF-IR signaling molecules including phosphorylated Akt, Erk1/Erk2 and STAT3. Therefore, these transgenic mice provide evidence that IGF-IR overexpression is sufficient to induce mammary epithelial hyperplasia and tumor formation in vivo and provide a model to further understand the function of IGF-IR in mammary epithelial transformation.

Multinuclear Luminescent Schiff-Base Zn−Nd Sandwich Complexes

Multinuclear 3d-4f complexes with sandwichlike molecular structures are formed with the Schiff-base ligand bis(3-methoxysalicylidene)ethylene-1,2-phenylenediamine(H(2)L). The stoichiometry and structures are dependent on the Zn:Nd ratio and counteranions present. They are trinuclear [Nd(ZnL)2(NO3)2(H2O)2].NO3.EtOH.H2O (1), [Nd(ZnL)2Cl2(H2O)3].Cl.2MeOH.5H2O (2), and tetranuclear [Nd2(ZnL)2Cl6(MeOH)2].MeOH (3). Dinuclear complex [NdZnL(NO3)3MeCN].MeCN (4) was also characterized. Near-infrared (NIR) lanthanide luminescence is observed in these complexes.

Dynamic contrast-enhanced MR urography in the evaluation of pediatric hydronephrosis: Part 1, functional assessment

OBJECTIVE

The purpose of our study was to derive time-intensity curves for the renal cortex and medulla from 3D dynamic MR urography and to assess whether these curves are predictive of obstruction.

MATERIALS AND METHODS

Fifty-nine examinations were performed in 53 pediatric patients and the degree of obstruction assessed using the renal transit time. The cortex and medulla were segmented using a semiautomatic method, and mean time-intensity curves were derived for the segmented volumes. The basic parameters of the curves (amplitude, washout) were assessed, as was the presence of certain characteristic features of the curves.

RESULTS

The images allowed clear visualization of three phases of the uptake of contrast material in the cortex, the medulla, and the collecting system. Both the amplitude of the curves and the washout of the contrast material were predictive of obstruction. The distal tubular peak was reliably detected in the cortex of nonobstructed kidneys.

CONCLUSION

Combining signal-intensity-versus-time-curve analysis with the other parameters that can be derived from the same MR urography data set provides a powerful tool for the diagnosis of obstruction.

Design and synthesis of a near infra-red luminescent hexanuclear Zn–Nd prism

The use of the Schiff-base ligand N,N'-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (H2L) and 1,4-benzenedicarboxylate (BDC) enables the construction of the hexanuclear luminescent Zn-Nd complex [Zn4Nd2L4(1,4-BDC)2].[Nd(NO3)5(H2O)].Et2O.2EtOH.3H2O.

Reversible guest molecule encapsulation in the 3-D framework of a heteropolynuclear luminescent Zn4Eu2 cage complex

Guest molecules of diethyl ether or methanol are reversibly encapsulated in cavities formed by the 3-dimensional supramolecular framework of heteropolynuclear, luminescent [Eu2Zn4L4(OAc)6(NO3)2(OH)2].2Et2O.

Dynamic Contrast-Enhanced MR Urography in the Evaluation of Pediatric Hydronephrosis: Part 2, Anatomic and Functional Assessment of Uteropelvic Junction Obstruction

OBJECTIVE

The purpose of our study was to retrospectively review our experience using MR urography in the diagnosis of ureteropelvic junction (UPJ) obstruction in children.

MATERIALS AND METHODS

Sixty-one studies were performed in 50 children with hydronephrosis but without hydroureter. Anatomic criteria assessed included degree of hydronephrosis, morphology of the renal pelvis, atrophy of medulla, swirling contrast material, fluid levels, and the presence of fetal folds and crossing vessels. Functional criteria included renal transit time, differential renal function, and time-intensity curves when available.

RESULTS

Thirty-one kidneys were classified as obstructed, 15 as equivocal, and 15 as nonobstructed. Obstructed systems had more marked hydronephrosis, more extensive medullary atrophy, more fluid levels, and more swirling contrast material. Fetal folds were seen in only the equivocal and nonobstructed groups. Crossing vessels were seen in all groups. Obstructed systems also showed greater functional derangement, decreased split renal function, and abnormal time-intensity curves.

CONCLUSION

MR urography provides both excellent anatomic and functional information in children with UPJ obstruction in a single test that does not use ionizing radiation. MR urography may lead to greater understanding of the pathophysiology of UPJ obstruction.

Matrix changes induced by transglutaminase 2 lead to inhibition of angiogenesis and tumor growth

Administration of active TG2 to two different in vitro angiogenesis assays resulted in the accumulation of a complex extracellular matrix (ECM) leading to the suppression of endothelial tube formation without causing cell death. Matrix accumulation was accompanied by a decreased rate of ECM turnover, with increased resistance to matrix metalloproteinase-1. Intratumor injection of TG2 into mice bearing CT26 colon carcinoma tumors demonstrated a reduction in tumor growth, and in some cases tumor regression. In TG2 knockout mice, tumor progression was increased and survival rate reduced compared to wild-type mice. In wild-type mice, an increased presence of TG2 was detectable in the host tissue around the tumor. Analysis of CT26 tumors injected with TG2 revealed fibrotic-like tissue containing increased collagen, TG2-mediated crosslink and reduced organized vasculature. TG2-mediated modulation of cell behavior via changes in the ECM may provide a new approach to solid tumor therapy.

Anion Dependent Self-Assembly of “Tetra-Decker” and “Triple-Decker” Luminescent Tb(III) Salen Complexes

The Schiff base complexes [Tb3L4(H2O)2]Cl and [Tb3L3(OAc)2Cl] both have unusual multi-decker architectures formed via intramolecular pi-pi interactions between phenylene units.

Synthesis and near infrared luminescence of a tetrametallic Zn2Yb2 architecture from a trinuclear Zn3L2 Schiff base complex

Near infrared luminescence is observed in tetrametallic [Zn2Yb2L2(mu-OH)2Cl4].2MeCN which is obtained from the Zn3 Schiff-base complex [Zn3L2(NO3)2].MeOH, (H2L =N,N'-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine).

The wear and fracture behaviour of ultra high molecular weight polyethylene subjected to gamma-irradiation in an atmosphere of acetylene

The wear and mechanical properties of GUR 1020 (Perplas IMP 2000-2) Ultra High Molecular Weight Polyethylene (UHMWPE) subjected to gamma-irradiation in an atmosphere of acetylene, were evaluated for a range of processing conditions of irradiation, annealing and ageing. The results were compared with those obtained for the virgin UHMWPE material and material processed using conventional gamma-irradiation in nitrogen. Cross-linking produced by irradiation in acetylene, followed by subsequent annealing was found to be significantly more effective in improving the mechanical and wear properties of UHMWPE compared to when the material was irradiated in nitrogen. Gel fraction analysis on its own, while being able to detect the degree of cross-linking, was found to be insufficient in determining the effectiveness of the cross-links and the resulting mechanical properties of the UHMWPE material. The results suggest that gamma-irradiation in an atmosphere of acetylene may provide significant advantages over conventional UHMWPE processing and irradiation cross-linking techniques.

Renal transit time with MR urography in children

PURPOSE

To prospectively evaluate use of dynamic contrast material-enhanced magnetic resonance (MR) urography for measurement of renal transit time (RTT) of a contrast agent through the kidney and collecting system so as to identify obstructive uropathy in children.

MATERIALS AND METHODS

One hundred twenty-six children suspected of having hydronephrosis were hydrated prior to undergoing both conventional and dynamic contrast-enhanced MR urography of the kidneys and urinary tract. A three-dimensional sequence was used to track passage of contrast agent through the kidneys. Time between the appearance of contrast material in the kidney and its appearance in the ureter at or below the level of the lower pole of the kidney was defined as RTT. Bland-Altman plots were used to quantify intra- and interobserver performance. In 30 children, a nuclear medicine renogram was also obtained, and the half-life of renal signal decay after furosemide administration was derived and compared with the MR imaging RTT by using receiver operating characteristic curves.

RESULTS

On the basis of RTT, kidneys were classified as normal (RTT </= 245 seconds), equivocal (245 seconds > RTT </= 490 seconds), or obstructed (RTT > 490 seconds). Inter- and intraobserver agreement indicated that the technique is both robust and reproducible. Receiver operating characteristic analysis for comparison of results of MR imaging and diuretic renal scintigraphy showed good agreement between the modalities, with a mean area under the curve of 0.90.

CONCLUSION

When used in conjunction with morphologic images obtained in the same examination, RTT generally allowed normal kidneys to be differentiated from obstructed and partially obstructed kidneys.

A nanoscale slipped sandwich of Tb(10)-stabilization of a benzaldehyde methyl hemiacetyl

A nanoscale slipped sandwich of Tb(10) is formed from the reaction of 5-bromo-3-methoxysalicylaldehyde (HL) with TbCl(3)x6H(2)O and Zn(OAc)(2)x2H(2)O. The compound also features an unusual example of a coordinated methylhemiacetal which is derived from HL.

Radioactivity in cathode ray tubes

While surveying used computer equipment out of a zone posted as a Contamination Area, 100% of the computer monitors surveyed had levels of radioactivity that were significantly above background. The radioactivity was primarily on the front face of the cathode ray tube and was not amenable to decontamination. Hot spots were found also along the edges and seals of the cathode ray tube. Similar surveys of computer monitors that were never in Contamination Areas confirmed that radioactivity was incorporated into the monitor. Surveys were made of recently manufactured television sets with similar results. Gamma spectroscopy indicates that the radioactivity is due to naturally occurring radioactive materials. Since most surveys of cathode ray tubes in the literature were made while the units were energized and indicated low-energy x-rays, the use of naturally occurring radioactive materials in the manufacture of cathode ray tubes has not been widely recognized. This paper presents the results of these surveys, the results of gamma spectroscopy, and a method for releasing existing computer equipment having naturally occurring radioactive materials.

MRI of the Neonatal Brain:Optimization of Spin-Echo Parameters

OBJECTIVE

Our aim was to measure the relaxation times of the neonatal brain and to use these to derive pulse sequence parameters that enhance the signal-to-noise ratio (SNR) and contrast of MRI scans of the neonatal brain.

SUBJECTS AND METHODS

The transverse (T2) and longitudinal (T1) relaxation times were measured for 10 healthy neonates, and the average relaxation times were calculated for both gray and white matter. Simulations using these values were then performed to estimate the optimal pulse sequence parameters. Images were obtained in three neonates using both the optimized and conventional sequence parameters.

RESULTS

The measured (mean +/- SD) relaxation times of the neonatal brain at 1.5 T were T1 equals 1712 +/- 235 msec and T2 equals 394 +/- 52 msec in white matter and T1 equals 1144 +/- 245 msec and T2 equals 206 +/- 26 msec in gray matter. The optimized T1-weighted imaging used a turbo spin-echo sequence with an echo-train length of 3 and TR/TE of 850/11 msec and showed increases in both the contrast and the SNR. The optimized T2-weighted sequence used a TE of 270 msec and markedly increased the contrast but at the expense of a reduction in the SNR.

CONCLUSION

Parameters of MRI turbo spin-echo sequences for scanning neonates are different from those required for adult studies, and appropriate protocols should be used.

Synthesis and structure of Zn7(µ4-O)2(OAc)10(Pz)2(OAc = acetate; Pz = pyrazine)

Reaction of Zn(OAc)(2).2H(2)O with pyrazine in refluxing ethanol gives the unusual heptanuclear complex Zn7(mu4-O)(2)(OAc)(10)(Pz)(2) (1) (OAc = acetate, Pz = pyrazine) in 46% yield. A single-crystal X-ray diffraction study of revealed a central Zn(7) core in which two pseudo-tetrahedral Zn(4) units are joined at a common vertex. The two pyrazine molecules are bound as terminal (eta1) ligands.

Age dependence of the renal apparent diffusion coefficient in children

BACKGROUND

Diffusion imaging has proved to be a powerful tool for diagnosing ischemic lesions in the brain, and the technique is now being applied to other organs, including the kidneys. For quantitative studies it is important to define the normal values of the apparent diffusion coefficient (ADC), given the important physiological changes that occur in the kidney during early childhood it is likely that the ADC changes markedly during this period. OBJECTIVE. To evaluate the age dependent changes in the ADC of normal kidneys in the pediatric population.

MATERIALS AND METHODS

The whole kidney ADC was calculated for 62 pediatric patients on a 1.5-T system using a respiratory-triggered, single-shot diffusion tensor imaging sequence with b values of 50, 200, and 350 mm(2)/s. RESULTS. The ADC was found to increase with age with the largest increase being in the first year of life, the rate of change being described by a constant plus a power function, specifically 1349+[358.5*[age 0.34]], ( P<0.001).

CONCLUSION

The renal ADC changes significantly during childhood.

The evolution of the apparent diffusion coefficient in the pediatric brain at low and high diffusion weightings

PURPOSE

To evaluate the evolution of the apparent diffusion coefficient (ADC) with age for different degrees of diffusion weighting using a clinically feasible approach.

MATERIALS AND METHODS

Data was acquired using separate scans with b values in the range typically used for clinical studies (100-900 seconds/mm(2)) and higher b values (1800-3000 seconds/mm(2)). The ADC was calculated for each of the data sets by fitting the data to a monoexponential function.

RESULTS

The results from 50 children aged three years and less showed some deviations from literature values derived using a full biexponential fit, with these differences reflecting the approximations inherent in this approach. The values obtained with this technique appear to be reproducible but the resulting "institutional values" are comparable to those from other centers only if identical measurement criteria are used.

CONCLUSION

A significant decline in both components of the ADC during the first few months of life was observed; in addition, the attenuated slow ADC values seen in adult white matter were only present at birth in early myelinating regions. The subsequent development of the slow ADC in white matter suggests that it is associated with myelination or processes associated with axonal development.

A prospective study comparing ultrasound, nuclear scintigraphy and dynamic contrast enhanced magnetic resonance imaging in the evaluation of hydronephrosis

PURPOSE

A combination of nuclear medicine, ultrasound and voiding cystourethrography is typically used to investigate hydronephrosis in children. A major problem is the lack of an accepted gold standard to assess obstruction. In some cases the anatomy is unclear. By combining anatomical and functional information in one study, magnetic resonance imaging (MRI) has the potential of providing superior information regarding hydronephrosis. We evaluate the role of dynamic enhanced MRI and compare it to other imaging modalities in the investigation of pediatric hydronephrosis.

MATERIALS AND METHODS

One hundred dynamic contrast enhanced MRIs were performed in 96 children (35 girls and 61 boys, mean age 4 years [range 1 month to 17 years]). The information from the various imaging modalities was compared.

RESULTS

The MRI protocol was acceptable to all families and was performed without complications in all patients. The morphological imaging with MRI was superior to conventional imaging in all cases. The split renal function as calculated by nuclear and MRI scans was compared in 71 cases, and the correlation coefficient was r2 = 0.93. The combination of ultrasound and a nuclear medicine study correlated with the final diagnosis of the MRI in 50 of 64 studies (78%). Of the 14 studies that differed 8 were obstructed on MRI but not on the nuclear studies, and 5 were not obstructed on MRI but were obstructed on the nuclear studies. One patient believed to have ureteropelvic junction obstruction on nuclear medicine scan had ureterovesical junction obstruction on MRI. The final diagnoses by MRI were ureteropelvic junction obstruction in 26 children, primary ureterovesical junction obstruction in 14, dilated but not obstructed systems in 35, duplex systems in 13, multicystic dysplastic kidneys in 5, unilateral small scarred kidney in 1, acute pyelonephritis in 2, renal mass in 1, bilateral polycystic kidneys in 1 and normal study in 9. Sedation was administered safely without any complications.

CONCLUSIONS

Dynamic contrast enhanced MRI provides equivalent information about renal function but superior information regarding morphology in a single study without ionizing radiation. MRI has the potential to replace the currently used combination of other imaging modalities in the investigation of hydronephrosis in children.

Influence of fMRI data sampling on the temporal characterization of the hemodynamic response

Experimental and modeling studies were used to estimate the effect of different sampling rates (repetition times, TR) and different sampling positions on the estimates of the temporal properties of the hemodynamic response function (HRF) derived from fMRI studies. Data were acquired at a TR of 250 ms and then subjected to various degrees of undersampling. Using a gaussian fitting function it is demonstrated that the accuracy of HRF peak time determination decreases with lower sampling rate (higher TR). The decrease in accuracy amounts to about 50 ms per second of TR increase. In addition, temporal shifts of the HRF peak time are found when reducing the influence of the more variable descending part of HRF curve by using a temporal cut-off after HRF peak time. The shift scales with TR, amounts up to 100 ms for a TR of 1500 ms and a cut-off of 3-4 s and depends on the sampling position. The use of the full HRF function does not lead to a shift but increases the influence of potential confounding factors as large veins and poststimulus undershoot. Since both accuracy and potential shifts of HRF peak determination scale with TR, it is important that temporal fMRI studies are carried out with high sampling rates.

MR imaging of kidneys: functional evaluation using F-15 perfusion imaging

BACKGROUND

Children with hydronephrosis are typically investigated by a combination of diuretic renal scintigraphy, ultrasound, and voiding cystourethrography. Unfortunately, there is no gold standard to assess obstruction.

PURPOSE

The purpose of our study was to evaluate the utility of dynamic contrast enhanced MR urography in the investigation of children with hydronephrosis to define urinary tract anatomy, to calculate differential renal function and to assess urinary tract obstruction.

MATERIALS AND METHODS

Dynamic contrast-enhanced MR imaging was performed in 40 children with unilateral hydronephrosis. There were 14 girls and 26 boys with an age range of 1 month to 14 years (mean 1.4 years). The information from traditional imaging modalities was compared to the information obtained from the single MR study.

RESULTS

The anatomic imaging with MR urography was superior to other modalities. The split renal function was estimated with MR urography by calculating the volume of enhancing renal parenchyma and was comparable to renal scintigraphy ( r=0.98). By using surgery versus non-surgery as the decision point, with MR urography the sensitivity was 100%, specificity 71%, positive predictive value 86%, negative predictive value 100%, and diagnostic efficiency 90%. For renal scintigraphy the sensitivity was 96%, the specificity 56%, positive predictive value 76%, negative predictive value 90%, and diagnostic efficiency 79%.

CONCLUSIONS

Dynamic contrast-enhanced MR urography provides superior anatomic and functional information when compared with ultrasound and diuretic renal scintigraphy. The information is gathered in a single study that does not use ionizing radiation. It is likely that MR urography will replace renal scintigraphy in the evaluation of hydronephrosis in children.

Novel supramolecular architectures in group 13 perfluoroaryl complexes. Synthesis and structures of [AlMe(C6F5)(mu-Me)]2 and GaMe(C6F5)2

Novel supramolecular architectures are observed in the solid state structures of [AlMe(C6F5)(mu-Me)]2 (1) and Ga(C6F5)2Me (2) via pi-pi stacking between C6F5 rings and intermolecular aryl-F-->Ga interactions, respectively.

Synthesis and structure of a novel supramolecular Zn3Co8 assembly containing a linear Zn3 core

Reaction of Zn(OAc)(2).2H2O (OAc = acetate) with LH2 in THF followed by reaction with Co2(CO)8 yields the novel supramolecular assembly Zn3L2(OAc)2[Co2(CO)6](4).0.5CH2Cl2, which was characterized by X-ray diffraction (LH2 = (CH2)3(N=CH-2-OH-5-C identical to CSiMe3C6H3)2 or N,N'-propylenebis(2-hydroxy-5-trimethylsilylethynl-1-aldimine).

Isolation and characterization of bone marrow multipotential mesenchymal progenitor cells

OBJECTIVE

There is an increased interest in rheumatology in mesenchymal progenitor/stem cells (MPCs) and their roles in rheumatic diseases, but little is known about the phenotype of these cells in vivo. The aim of this study was to isolate and characterize human bone marrow (BM) MPCs.

METHODS

Fluorescence microscopy was used to identify putative MPCs among adherent BM cells. To purify them, a positive selection with antifibroblast microbeads was used, combined with fluorescence-activated cell sorting (FACS) for microbead+,CD45(low) cells. A more detailed phenotype of these cells was determined using 4-color flow cytometry, and standard chondrogenic, osteogenic, and adipogenic assays were used to investigate their differentiation potentials.

RESULTS

Putative MPCs microscopically identified as large, fibroblast-like, D7-FIB+ cells were purified using positive selection with D7-FIB-conjugated (antifibroblast) microbeads followed by FACS for specifically bound microbead+,CD45(low) cells. These cells represented 0.01% of mononuclear cells in the BM. They were uniformly positive for CD105, LNGFR, HLA-DR, CD10, CD13, CD90, STRO-1, and bone morphogenetic protein receptor type IA (BMPRIA) and were negative for CD14, CD34, CD117, and CD133. Only cells with this phenotype could proliferate and produce adherent cell monolayers capable of chondrogenic, osteogenic, and adipogenic differentiation. D7-FIB- cells in the BM lacked any MPC activity. Uncultured skin fibroblasts had a phenotype similar to that of BM MPCs, but were negative for LNGFR, STRO-1, HLA-DR, and BMPRIA.

CONCLUSION

This study shows the distinct phenotype, morphology, and method of isolation of BM MPCs. The findings may have implications for defining the physiologic roles of MPCs in arthritis, bone diseases, and joint regeneration.